Symposium Organizers
Cengiz Ozkan, University of California, Riverside
Ali Coskun, Korea Advanced Institute of Science and Technology
Ekaterina Pomerantseva, Drexel University
Federico Rosei, Université du Quebec
ES04.01: Advances in Battery Technologies
Session Chairs
Cengiz Ozkan
Federico Rosei
Monday PM, November 27, 2017
Hynes, Level 3, Ballroom A
8:00 AM - *ES04.01.01
Making Li-Ion Batteries Safe and Flexible with Water
Kang Xu 1
1 Electrochemistry Branch, U.S. Army Research Laboratory, Adelphi, Maryland, United States
Show AbstractSolid electrolyte interphases (SEI) enable the Li-ion intercalation chemistries to operate reversibly beyond the thermodynamic stability limits of non-aqueous electrolytes 1. The chemical building blocks of SEI mainly come from solvents decomposition products. Exceptions arise, when salt anion are reduction-labile, or when salt concentration exceeds certain thresholds, where anion starts to participate in the interphasial chemistry 2~4.
Through understanding of SEI formation mechanism, Li+-solvation sheath structure was identified as a central factor in dictating the assembly and arrangement of SEI precursors at electrode surface 5. This knowledge provides an effective tool for us to tailor interphasial chemistries, and eventually leads us to extend the efforts into the realm of aqueous electrolytes, where SEI is hitherto unknown. The new class of aqueous electrolytes, with their widened voltage windows > 3.0 V 6~7, have opened up a series of new opportunities for advanced electrochemical storage technologies 8. This talk summarizes our efforts to explore this realm of “uncharted water”.
8:30 AM - ES04.01.02
Effect of Surface Chemistry and Crystallite Size on the Performance of Fe3O4 Li-Ion Battery Anodes
Krysten Minnici 1 , Yo Han Kwon 1 , Matthew Huie 2 , Mark de Simon 1 , Kenneth Takeuchi 2 , Esther Takeuchi 2 , Amy Marschilok 2 , Elsa Reichmanis 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 , Stony Brook University, Stony Brook, New York, United States
Show AbstractBattery electrodes are complex mesoscale systems comprised of an active material, conductive agent, current collector, and polymeric binder [1]. Previous work focused on enhancing electron and ion transport in high capacity anode systems by introducing poly[3-(potassium-4-butanoate) thiophene] (PPBT) as a binder component and a polyethylene glycol (PEG) surface coating on magnetite (Fe3O4) nanoparticles [2]. The PPBT/PEG system will be utilized in this work, which takes a closer look at the active material, Fe3O4, and examines the effects of surface chemistry and crystallite size (10 nm vs. 20 nm) on battery performance.
Variations in surface chemistry are due to the synthesis methods used for Fe3O4, which use ammonium hydroxide or triethylamine as a base. SEM images of the electrodes, which are composed of Fe3O4 particles, carbon additives, and the PPBT binder, indicated that the bases produce different morphologies. The Fe3O4 particles synthesized with ammonium hydroxide appeared more dispersed relative to those made with triethylamine, which could have a significant impact on the battery performance. Furthermore, XPS and FTIR data indicated that these bases produce difference chemical interactions within the electrode.
Battery testing demonstrated that the triethylamine-based electrode had slightly better capacity retention over 100 cycles at 0.3C, whereas the ammonium hydroxide-based electrode exhibited superior rate capability performance. In reference to differences in active material size, preliminary battery testing also indicated that the electrodes with 20 nm crystallite size Fe3O4 initially had a higher capacity, but the electrodes with 10 nm crystallite size Fe3O4 had better capacity retention over 100 cycles at 0.3C.
[1] Y. H. Kwon, M. M. Huie, D. Choi, M. Chang, A. C. Marschilok, K. J. Takeuchi, E. S. Takeuchi, E. Reichmanis, ACS Appl. Mater. Interfaces, 2016, 8 (5), 3452–3463.
[2] Y. H. Kwon, K. Minnici, M. M. Huie, A. C. Marschilok, K. J. Takeuchi, E. S. Takeuchi, E. Reichmanis. Chem. Mater., 2016, 28 (18), 6689–6697.
8:45 AM - ES04.01.03
Implementation of Tin Dioxide/Graphene/Graphene Oxide for High Capacity and Long Cycle Life Supercapacitors and as Anode Material for Lithium-Ion Batteries
Valerio Dorvilien 1 , Monica Lopez de Victoria 1 , Amal Suleiman 2 , Jose Nocua 3 , Balram Tripathi 1 , Frank Mendoza 1 , Carlos Cabrera 2 , Ram Katiyar 1 , Gerardo Morell 1 , Brad Weiner 2
1 Department of Physics, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico, United States, 2 Department of Chemistry, University of Puerto Rico at Río Piedras, San Juan, Puerto Rico, United States, 3 UHS, University of Puerto Rico at Río Piedras, San Juan, Puerto Rico, United States
Show AbstractEnergy storage and conversion mechanism are different for on lithium ion batteries (LIB) and supercapacitors (Electrical Double Layer Capacitors- EDLCs), materials that can be used for both could lead in the future the energy storage and conversion technologies. We explored a non-conventional process to synthesize SnO2/G/GO composite powder which is conformal structure was characterized under different techniques. Comprehensive analysis of the structural and chemical properties reveals that the material consists of highly dispersed SnO2 nanoparticles in G/GO matrix.
The dispersed SnO2/G/GO suspension was coated an aluminum foil for the supercapacitors electrodes. We examine the electrical conductivity of the electrodes by atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). We assembled the Al coated SnO2/G/GO composite as a supercapacitor inserting one solid-state electrolyte between two electrodes, assembled into a sandwich structure. The specific capacitance and cycle-life stability of the supercapacitor was investigated by cyclic voltammetry analysis. For LIB applications, the SnO2-G/GO composite exhibited high capacity and excellent electrochemical performance as anode material. For both applications, the quantitative/qualitative results show that G/GO is providing contact areas which results in more energy density at the interface electrode/electrolyte and that the SnO2 provides additional ions to the EDL and the electrochemical process. The Overscreening phenomena observed, which is a function of ionic size, surface charge density of the electrodes, can also be a function of concentration of the electrolyte, porosity of the electrodes (G/GO)
9:00 AM - ES04.01.04
Interfacial Reactivity Descriptor at Oxide-Electrolyte Interface in Li-Ion Batteries
Livia Giordano 1 , Pinar Karayaylali 1 , Yang Yu 1 , Yu Katayama 1 , Filippo Maglia 2 , Simon Lux 2 , Yang Shao-Horn 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , BMW Group, München Germany
Show AbstractUnderstanding electrochemical and chemical reactions at the electrode-electrolyte interface is of fundamental importance for the safety and cycle life of Li-ion batteries. Positive electrode materials such as layered transition metal oxides have been reported to exhibit different degrees of chemical reactivity with commonly used carbonate-based electrolytes [1-5], although a comprehensive understanding of the parameters governing such reactivity is still lacking. Here we employed density functional theory methods to compare the energetics of four different chemical reactions between ethylene carbonate (EC) and layered (LixMO2; M = Mn, Fe, Co and Ni; x = 1, 0.5, 0) and rocksalt (MO; M = Mn, Fe, Co and Ni) oxide surfaces. EC dissociation on layered oxides was found energetically more favorable than electrophilic attack, nucleophilic attack and EC dissociation with oxygen extraction from the oxide surface. The dissociation is accompanied by an interfacial charge transfer, where the solvent molecule is oxidized while the transition metal oxide is reduced. In addition, EC dissociation became energetically more favorable on oxide surfaces with transition metal ions from left to right in the periodic table or by increasing transition metal valence in the oxides, where greater EC dissociation was found as the Fermi level was lowered into the oxide O 2p band.
[1] D. Aurbach et al., J. Electrochem. Soc. 147, 1322 (2000).
[2] K. Leung, J. Phys. Chem. C 116 , 9852 (2012).
[3] O. Borodin et al., Nanotechnology, 26, 354003 (2015).
[4] J. L. Tebbe et al., ACS Appl. Mater. Interfaces 8, 26664 (2016).
[5] S. Xu et al., ACS Appl. Mater. Interfaces, in press (2017).
9:15 AM - ES04.01.05
Engineered Current Collector Interface for High Energy Density Li-Ion Batteries
Lakshman Ventrapragada 1 , Apparao Rao 1 , Ramakrishna Podila 1
1 Clemson Nanomaterials Institute, Clemson University, Clemson, South Carolina, United States
Show AbstractLi-ion rechargeable batteries (LIBs) are the most promising candidates for use in electric and hybrid electric vehicles (EVs and HEVs) due to their high operating voltage and superior energy density compared to other conventional batteries such as the Ni-metal hydride battery. To enable cost-effective and long-lasting EVs, DoE estimates that the performance of present battery systems must be improved by at least four times without increasing the cost. LiFePO4 (LFP) emerged as a competitive cathode material for next-generation LIBs due to its remarkable stability and non-toxicity but they suffer from low electrical conductivity. While the addition of carbon improves the in-plane electrical conductivity, it fails to provide a conducting interface between the LFP/C/binder film and the current collector. This interfacial resistance at the current collector and active material interface (CCAMI) is critical for achieving high power density and rate capability but is often neglected. We addressed this issue by engineering the CCAMI with carbon nanotubes (CNTs). Previously, we demonstrated two roll-to-roll binder-free processes for coating Al foils with CNTS: (i) a CVD-based process for directly growing vertically aligned CNTs (VACNTs) on bare kitchen-grade Al foils [1], and (ii) a spray-coating process for coating industrial-grade Al foils with randomly oriented CNTs [2]. The above mentioned processes eliminate the need for a binder and thereby reduce both the dead weight of the inactive material and the CCAMI resistance. Specifically, we found that the VACNTs- or randomly oriented CNTs-coated Al foils obtained via our roll-to-roll processes enhance the areal (/gravimetric) capacity of LFP by >65% (/>50%) at low C-rates (<2 C), and by >85% (>70%) at high C-rates (>2 C). Moreover, the improved CCAMI resulted in gravimetric energy densities up to 360 Wh/kg and power densities up to 200 W/kg with much higher power capability (increased charge capacity at high discharge rates). Thus, this study describes an attractive approach for improved CCAMI, which is scalable and compatible with existing industrial protocols for coating LFP and takes us many steps closer to the commercial deployment of LIBs in HEVs and EVs.
[1] M. R. Arcila-Velez et al., Nano Energy. 8 (2014) 9–16. doi:10.1016/j.nanoen.2014.05.004.
[2] M. Karakaya et al., Appl. Phys. Lett. 105 (2014). doi:10.1063/1.4905153.
9:30 AM - ES04.01.06
Computer Aided Optimization of Structured Superparticles for Lithium-Ion Battery Electrodes
Michael Bieri 1 , Mathieu Luisier 1
1 , ETH Zurich, Zurich Switzerland
Show AbstractAssembling nanoparticles into micrometer-sized spherical superparticles is a promising approach for realizing Lithium Ion Battery (LIB) electrodes with enhanced functionalities (good tradeoff between energy and power density, large volume change accommodations, short ion diffusion lengths) [1]. Different experimental techniques such as spray drying or hydrothermal synthesis have been successfully applied to create superparticles with well-controlled porosity. Similarly, the size, shape, material composition, and orientation of the underlying nanoparticles can be more and more precisely determined, thus giving rise to a huge design space to explore in order to obtain LIBs with the best possible performance.
This is where computer aided design (CAD) comes into play: by allowing for the rapid investigation of a large number of superparticle configurations it can guide the experimental work towards the most promising solution(s) and help assess the potential of a given material or fabrication process. The first CAD ingredient is a state-of-the-art microscopic LIB simulator. Up to date Newman’s model remains the reference for that [2]. While free implementations of this approach can be found for one- and two-dimensional structures, only commercial products are available for 3-D ones. Such a high sophistication level is however imperatively needed for superparticle design, together with the possibility to run tens of simulations at the same time without worrying about software license issues.
We are therefore developing a free 3-D LIB simulator based on the Finite Element Method (FEM) to get rid of the limitations mentioned above. First, a geometry generator and mesher have been assembled to construct superparticles made of nanoparticles with any material composition, shape, size, and orientation. Secondly, a 3-D FEM solver has been written to compute the current distribution, electrostatic potential, and Li ion concentration of the virtually fabricated superparticles. Besides these accurate device modeling capabilities, big data techniques are required to handle the automatic design space exploration and make it converge towards the optimal parameter combination. Hence, we will demonstrate at the MRS conference how the proposed “simulation+optimization” technique can be used to improve the performance of LIBs in terms of energy and power density without multiple try-and-error iterations. Lithium Titanate superparticles will serve as an illustration example.
[1] L. V. Novack et al., Adv. Sci., 2: 1500078 (2015).
[2] M. Doyle, T.F. Fuller, J. Newman, J. Electrochem. Soc. 140 (1993) 1526.
9:45 AM - ES04.01.07
Regenerative Polysulfide-Scavenging Layers for Lithium-Sulfur Batteries
Fang Liu 1 , Yunfeng Lu 1
1 , University of California, Los Angeles, Los Angeles, California, United States
Show AbstractLithium-sulfur batteries, notable for high theoretical energy density, environmental benignity and low cost, hold great potentials for next-generation energy storage. Polysulfides, the intermediates generated during cycling, may shuttle between electrodes, compromising the energy density and cycling life. We report herein a class of regenerative polysulfide-scavenging layers, which effectively immobilize and regenerate polysulfides, especially for electrodes with high sulfur loadings (e.g., 6 mg cm-2). The resulted cells exhibit high gravimetric energy density of 365 Wh kg-1, initial areal capacity of 7.94 mAh cm-2, low self-discharge rate of 2.45% after resting for 3 days and dramatically prolonged cycling life. Such blocking effects have been thoroughly investigated and correlated with the work functions of the oxides, as well as their bond energies with polysulfides. This work offers not only a class of regenerative polysulfide-scavenging layers to mitigate shuttling effect, but also a quantified design framework for advanced lithium-sulfur batteries.
ES04.02: Supercapacitors I
Session Chairs
Ekaterina Pomerantseva
Kang Xu
Monday PM, November 27, 2017
Hynes, Level 3, Ballroom A
10:30 AM - ES04.02.01
One-Step Fabrication of Nanostructured MnO2/MWCNT Electrodes Using Electric-Field-Driven Combustion Waves for High Performance Pseudocapcitor
Taehan Yeo 1 , Wonjoon Choi 1
1 Mechanical Engineering, Korea University, Seoul Korea (the Republic of)
Show AbstractPseudocapacitor is one of the most explored electrochemical energy storage device, due to the highly effective capacitance, depending on the electrodes. However, the redox cycles in pseudocapacitor induce the thermal-chemical degradation of electrodes materials, which results in low stability, while the limitation of surface area should be improved for the high specific capacitance. In this work, we present a novel, one-step method to fabricate the nanostructured MnO2/MWCNTs electrodes, using electric-field-driven combustion waves for high performance pseudocapacitor. The hybrid structures of nitrocellulose/MnO2/MWCNTs were fabricated by a wet impregnation and a vacuum filtration methods. The application of the DC electric field for the hybrid composites enabled the self-propagating combustion waves, which could manipulate the specific physicochemical properties of the remained MnO2/MWCNTs nanostructures. Owing to high temperature environment and guided-alignment of nanostructure via DC electric field, the physical bonding between MWCNTs and MnO2 was improved, and the unique crystals were formed by arc discharge among MWCNTs. The fabricated MnO2/MWCNTs-based pseudocapacitor electrodes showed highly improved specific capacitance (~530 F/g), as well as the long-term stability in charge-discharge cycling tests (~3000 times). In terms of the processing conditions, from the synthesis of nanostructures to the fabrication of electrodes, whole processes were conducted by one-step combustion waves with electric field through the hybrid composite. The developed method in this work would be applicable to other metal oxide-based electrochemical applications to improve the performance and stability, with the simple route for fabrication.
10:45 AM - ES04.02.02
All-Solid-State Flexible Supercapacitors Based on Carbon Nanotube-PDMS Structures
Runzhi Zhang 1 , Junjun Ding 1 , Chao Liu 1 , Eui-Hyeok Yang 1
1 , Stevens Institute of Technology, Hoboken, New Jersey, United States
Show AbstractFlexible electronics have a wide range of applications in wearable and multifunctional electronics[1]. Consequently, technologies for flexible energy storage have to be developed for flexible electronic devices[2,3]. Here, we demonstrate a facile fabrication of flexible supercapacitors utilizing vertically aligned carbon nanotubes (VACNTs) combined with polydimethylsiloxane (PDMS). The entire fabrication process allows a rapid and facile fabrication and integration of VACNT/PDMS substrate. The VACNT structures possess a high surface area, which is a key for flexible supercapacitors with high capacitances. Our unique technique ensures a strong adhesion between VACNTs and PDMS, which facilitates a stable charge-discharge under varied strain conditions.
First, we synthesize VACNTs using atmospheric-pressure chemical vapor deposition (APCVD) into carpet-like structures. Fe and Al catalysts are deposited using physical vapor deposition on a SiO2 wafer. The wafer is put inside the furnace, and the temperature is increased to 7500C under Ar and H2 flow. When the temperature reaches 7500C, a mixture of C2H4,H2 and Ar gases (100:50:500 sccm) is fed through the furnace. VACNT carpets are grown over the catalyst upon cooling the system.
Then we transfer the VACNTs onto a partially cured PDMS substrate, where PDMS infiltration between carbon nanotubes enhance the adhesion between VACNTs and PMDS. The electrochemical property of VACNTs on PDMS is measured in 30% KOH using cyclic voltammetry. The measured capacitance is 170 µF/cm2 at a high scan rate of 1 V/s. The structure is tested under a tensile strain of up to 200%, wherein the capacitance is attenuated by 50% of its value without the tensile strain. The structure is furthermore tested for 200 charge-discharge cycles under stretching, at which the capacitance is reduced to 75% of its initial value. The structure can be easily folded (i.e., bent by 1800) without deteriorating the integrity of the CNT/PDMS structure. We furthermore observe that the measured capacitance remains unchanged under various bending angles from 00 to 1800.
Finally we fabricate an all-solid-state flexible supercapacitor using a PVA-KOH gel electrolyte, and fully characterize its performance at various strain values(stretching, bending and twisting). The charge/discharge performance and cyclic behavior of the flexible supercapacitor show a stable charge/discharge performance for over 2000 cycles. This fabrication technique has great potential in producing flexible supercapacitors.
[1] Shao, Yuanlong, et al. "Graphene-based materials for flexible supercapacitors." Chemical Society Reviews 44.11 (2015): 3639-3665.
[2] Xi, Shuaipeng, et al. "Flexible supercapacitors on chips with interdigital carbon nanotube fiber electrodes." Materials Letters 175 (2016): 126-130.
[3] Yu, Dingshan, et al. "Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage." Nature nanotechnology 9.7 (2014): 555-562.
11:00 AM - ES04.02.03
Surface-Modified Electrospun Nanofibers Fabricated via Ultrasonic In Situ Spray Coating of Carbon Nanoparticles for Flexible Electrochemical Capacitor Electrodes
HaoTian Shi 1 , Hani Naguib 1
1 , University of Toronto, Toronto, Ontario, Canada
Show AbstractA novel surface-modified nano-fibrous electrode was fabricated via simultaneous ultrasonic spraying of multiwalled carbon nanotubes (MWCNT) during electrospinning process targeted for electrochemical capacitor (EC) applications. The use of ultrasonic nozzle acts as a spray coating mechanism, whereby the active MWCNT were effectively impinged onto the polyacrylonitrile (PAN) nanofiber surface while the electrospun polymer stream is yet solidified, creating an effective route for in-situ surface modification. This method led to highly conductive surfaces with comparatively low sheet resistance, while allowing higher specific surface area to be in contact with the electrolyte for higher charge storage capabilities. The ultrasonic nozzle helps further reduce the fiber diameter by blowing to apply extensional stress onto fiber while the leading to length extension. The enhanced electrical activity combined with smaller fiber diameters of 20-30 nm is also advantageous for efficient electrolytic ion transport during the EC charge-discharge processes, as demonstrated with smaller charge transfer impedances. This also allows a uniformly coated surface while enabling the nanofiber to retain its mechanical flexibility during mechanical stretching and bending. Two-electrode EC cells were constructed with aqueous sulphuric acid and polyvinyl alcohol (PVA) gel electrolyte to evaluate its electrochemical performances. The flexibility aspect of the EC was also addressed via mechanical bending and stretching testing to confirm that the electrochemical performance was not sacrificed even with applied stress. Additionally, with the nano-fibrous layer serving to separate the carbon nanoparticle layers, it is easier for the electrolytic ions to fully interact with the layered additional MWCNT and prevents undesired stacking or agglomeration associated with carbon-based nanoparticles. This novel method of applying surface-modification on nano-sized fibrous structures can be utilized with other polymer/particle combinations for further electrochemical performance enhancement.
11:15 AM - ES04.02.04
Molecular Simulation Study on Interfacial Humid Ionic Liquids in Supercapacitors
Sheng Bi 1 , Guang Feng 1 , RunXi Wang 1 , Rui Qiao 3 , Alexei Kornyshev 2
1 , HuaZhong University of Science and Technology, Wuhan China, 3 , Virginia Tech, Blacksburg, Virginia, United States, 2 , Imperial College London, London United Kingdom
Show AbstractIn recent years, supercapacitors, also called electrical double layer capacitors (EDLCs), or ultracapacitors, have attracted significant attention as a new class of the electrical energy storage devices due to their advantageous properties, such as high-power density and long cycle life. Room-temperature ionic liquids (RTILs) are an emerging class of ionic materials with many unique properties, such as excellent stability, low volatility and wide electrochemical windows. Those properties make RTILs potentially promising materials for electrochemical applications, such as energy storage and electrodeposition. Indeed, by using RTILs as electrolytes, impressive improvement of supercapacitors has recently been demonstrated in well-controlled laboratory systems. However, one practical issue in IL-based supercapacitor is the contamination by water. Since the complete removal of water from ionic liquids is nearly impossible, and such water content can potentially determine whether key advantages of RTILs, such as a wide electrochemical window, can be harnessed in practical systems.
In this talk, using molecular dynamics (MD) simulation, we show the first work on the adsorption of water on carbon electrode surfaces in contact with humid ILs. We found that water is generally enriched within sub-nanometer distance from charged electrodes. The level of enrichment depends on the type of ions and typically increases as the potential of electrodes increases. We clarified the mechanisms of these electrosorption behaviors. We highlighted the key role of ion-water association and interactions between water dipole and inhomogeneous electrical fields in double layers in determining water electrosorption, and rationalized the ion specificity and the asymmetrical dependence of electrosorption on the polarity of electrode charge. We also investigated influence of electrode materials (carbon vs. gold) on the interfacial humid ionic liquids and how the nature of ILs affects the adsorbed water distribution. We found that gold is quite different from carbon for presenting the microstructure of ion distribution as well as the EDL capacitance and the hygroscopicity of ILs has a great impact to electrosorption of water.
11:30 AM - ES04.02.05
Silver Nanowires for Supercapacitor Electrodes
Recep Yuksel 1 , Sahin Coskun 1 , Husnu Unalan 1
1 , Middle East Technical University, Ankara Turkey
Show AbstractSilver nanowires (Ag NWs) are appealing candidates for supercapacitor electrodes due to their high conductivity in addition to their allowance for all active materials to be in close contact to facilitate charge transport. All are very important to attain maximum charge accumulation provided that Ag NWs are electrochemically stable within the utilized potential window. In this work, high aspect ratio Ag NWs are used within a coaxial and/or network-like nanocomposite structure in supercapacitor electrodes. Utilization of Ag NWs as conductive templates also results in rapid deposition of electrode active materials. We have fabricated supercapacitors using Ag NWs and their nanocomposites with molybdenum oxide (MoO2) (500.7 F g-1) [1], nickel hydroxide (Ni(OH)2) (1165.2 F g-1) [2], polypyrrole (PPy) (70.4 F g-1) and some PEDOT derivatives (68.2 F g-1). Highly conductive Ag NWs were utilized as the only current collectors and templates for these electrode active materials. Electrochemical properties of the fabricated Ag NW based nanocomposite supercapacitor electrodes were investigated through galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. We will present a detailed analysis of utilization of Ag NWs in the fabricated supercapacitors to underline their charge transport behavior. Our results showed the potential of the use of Ag NWs in energy storage devices and the structures presented in this work is highly plausible and can be easily extended to other metal nanowire, metal oxide and conducting polymer systems.
[1] R. Yuksel, S. Coskun, H. E. Unalan, Coaxial Silver Nanowire Network Core Molybdenum Oxide Shell Supercapacitor Electrodes, Electrochim. Acta, 193 (2016) 39-44.
[2] R. Yuksel, S. Coskun, Y. E. Kalay, H. E. Unalan, Flexible, Silver Nanowire Network Nickel Hydroxide Core-Shell Electrodes For Supercapacitors, J. Power Sources 328 (2016) 167-173
11:45 AM - ES04.02.06
Three-Dimensional Conductive Porous Carbon X-Aerogels for Supercapacitors and Lithium–Oxygen Batteries
Christine H. J. Kim 1 , Dandan Zhao 2 , Gyeonghee Lee 1 , Jie Liu 1
1 , Duke University, Durham, North Carolina, United States, 2 , Lanzhou University, Lanzhou China
Show AbstractDeveloping macroscopic three-dimensional (3D) conductive porous materials with high mechanical strength is of practical importance in many fields, including energy storage, sensing, catalysis, etc. Many studies have tried to achieve this by making 3D assemblies from one-dimensional (1D) carbon nanotubes (CNTs) and two-dimensional (2D) graphene, referred to as CNT sponges and graphene aerogels. However, these materials have several limitations for practical applications, such as high production costs, unstable structures, and low volumetric energy density. To solve these problems, we develop a novel approach to fabricate polymer-cross-linked 3D carbon x-aerogels, a special type of aerogels with mechanically strong, highly cross-linked structure that allows the originally brittle aerogels to be machinable. This approach is facilitated by the sol–gel process of resorcinol, formaldehyde, and graphene, followed by CO2 activation and subsequent cross-linking with conducting polymer (e.g. polyaniline, polypyrrole) via electropolymerization. These x-aerogels are not only porous and conductive, but also mechanically robust with high compressibility and fast recovery. Furthermore, monoliths of the x-aerogels are machinable into thin slices without losing their properties, therefore enabling effective integration into devices with different sizes and shapes. Using these synergistically combined properties of the x-aerogels for high performance supercapacitors, we show that the multi-functionality leads to a considerable increase in electrochemical performance, in particular high volumetric capacitance that results from the densely packed electroactive structure in three dimensions. Recently, lithium–oxygen (Li–O2) batteries have been in the spotlight as the “next generation lithium-ion technology”. When extending the potential of the x-aerogels to Li–O2 batteries, their performance is even further improved. Effectively, the capacity, rate capability, and cycle life significantly increase thanks to the synergy between the 3D porous conductive carbon aerogel framework and the conducting polymer catalytic layer, which not only maintains stable catalytic activity without deactivation but also provides a more effective gas-liquid-solid interface for rapid oxygen absorption and diffusion. Our carbon x-aerogels, as 3D multifunctional materials, will find many other applications, such as water purification, oil–water separation, catalyst supports, and sensors.
ES04.03: Other Battery Materials I
Session Chairs
Francesca Iacopi
Mihri Ozkan
Monday PM, November 27, 2017
Hynes, Level 3, Ballroom A
1:30 PM - *ES04.03.01
Na-Air Batteries—Challenges and Progresses
Xueliang Sun 1 , Yang Zhao 1
1 , University of Western Ontario, London, Ontario, Canada
Show AbstractAlkali metal-oxygen (Li-O2, Na-O2) batteries have attracted a great deal of attention recently due to their high theoretical energy densities, which is comparable to gasoline, making them attractive candidates for use in electrical vehicles. However, the limited cycling life and low energy efficiency (high charging overpotential) of these cells hinder their commercialization [1,2]. Li-O2 battery system has been extensively studied in this regard during the past decade. Compared to the numerous reports of Li-O2 batteries, the research on Na-O2 batteries is still in its infancy. Although Na-O2 batteries show a number of attractive properties such as low charging overpotential and high round-trip energy efficiency, their cycling life is currently limited to a few tens of cycles. Lithium and sodium elements share similar chemical properties, however, the chemistry and electrochemistry of Li- and Na-O2 batteries are not the same. While the discharge product of Li-O2 cells is well-recognized to be lithium peroxide (Li2O2), both sodium peroxide (Na2O2) and superoxide (NaO2) have been detected as the discharge product of Na-O2 cells in a number of different studies. Therefore, understanding the chemistry behind Na-O2 cells is critical towards enhancing their performance and advancing their development.
Our group applied nanostructured carbon materials as cathodes to investigate various effects including surface area of porous carbon black [3], current density on CNTs [4] and functional groups on graphene [5], 3D electrodes [6] and humidity on rechargeability [7] as well as on effect of catalysts on cycling ability [8,9] and protection of Na metal [10].
In this talk, I will review recent progresses in this field, followed by talking our work. The perspectives will also be discussed.
References:
[1] H. Yadegari, Q. Sun and X. Sun*, Na-O2 Batteries-A Review, Adv. Mater. 2016, 28, 7065
[2] J. Wang, Y. Li and X. Sun*, Nano Energy, 2, 443-467(2013).
[3] H. Yadegari, Y. Li, Q. Sun, X. Sun*, et. al., Energy Environ. Sci., 7, 3747(2014).
[4] Q. Sun, H. Yadegari, and X. Sun*, et al., Nano Energy 12, 698-708(2015).
[5] Y. Li, H. Yadegari, X. Li, M. Banis, X. Sun*, Chem. Commun. 49, 11731-11733(2013).
[6] H. Yadegari, X. Sun* et al., Chemistry of Materials, 27, 3040-3045(2015).
[7] Q. Sun, H. Yadegari, and X. Sun*, et al., J. Phys. Chem. C 119, 13433-13441(2014).
[8] Q. Sun, H. Yadegari, X. Sun*, et al., Adv. Funct. Mater., (2017) In press
[9] H. Yadegari, Q. Sun and X. Sun*, Energy Environ. Sci., 10, 286-295(2017).
[10] Y. Zhao, Q. Sun, X. Sun* et al, Adv. Mater., (2017) In press
2:15 PM - ES04.03.03
Surface Modified Metal Hydrides as Negative Electrodes in NiMH Batteries
Cavit Eyövge 3 1 2 , Ezgi Onur Sahin 1 2 , Tayfur Ozturk 1 2
3 Mesoscale Chemical Systems, MESA+ Institute for Nanotechnology, University of Twente, Enschede Netherlands, 1 Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara Turkey, 2 ENDAM, Center for Energy Storage Materials and Devices, Middle East Technical University, Ankara Turkey
Show AbstractThere is a renewed interest in NiMH batteries with improved energy densities that could approach those of Li-ion batteries. Efforts to improve the energy density concentrates on alternative anode as well as cathode materials. For anode, AB2 and Mg based alloys are candidates with potentials that go beyond the capacity achieved with rare-earth based AB5 compounds.
In a recent study [1] we have shown an AB2 alloy which is sluggish in its activation could readily be activated when it was surface modified with hot-alkaline treatment. The treatment resulting in fine porous surface rich in Ni not only activates the alloy but it also increases the discharge capacity by a significant amount. This was attributed to positive effect of porous surface where hydrogen evolution was made difficult by the associated stabilizing effect. For Mg based alloys, we have investigated A2B7 alloy where the amount of Mg is quite low and an amorphous Mg50Ni50 alloy. Here rather than modifying the powders, the electrode itself was modified by nafion coating. The electrodes were tested both in bare and coated form with a notable difference in discharge capacity. Nafion coating increased maximum attainable discharge capacity in both alloys up to 150%. Electrochemical impedance spectroscopy measurements showed that the charge transfer resistance increases with increased coating. The role of nafion coating in developing Mg based negative electrode materials is discussed.
[1] Tan S., Shen Y., Sahin E. O., Noréus D., Ozturk T., "Activation behavior of an AB2 type metal hydride alloy for NiMH batteries" International Journal of Hydrogen Energy 41 (23), 9948-9953,2016
2:30 PM - ES04.03.04
Ion Conducting Ceramic-Based Composite Electrolyte for High Voltage Na-Ion Batteries
Young Jun Lim 1
1 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
Show AbstractThe most critical issues of this rechargeable battery system are safety manner. Typically used carbonate organic liquid electrolytes have high flammability and poor thermal stability. To solve these problems, there are many studies to replace the organic liquid electrolyte with non-flammable liquid or solid electrolyte. Solid ceramic electrolytes have been investigated as an alternative electrolyte for Na ion batteries due to high voltage stability, thermal stability, and provide fast ion transportation. However, large interfacial resistance between solid-solid particles is critical issue to use Na ion battery electrolyte. Nowadays, fabricating solid-state cell need special procedures to reduce these solid-solid interface resistances such as high-pressure unit or atomic layer thin film. Therefore, it is necessary to develop a new design of solid electrolyte system that can solve the interfacial resistance problem and be easily applicable to the process. In view of this, we designed a new type of composite electrolyte that combined NASICON-type sodium conducting ceramic(Na3Zr2Si2PO12), Na ionic liquid-based electrolyte comprising a sodium salt (sodium bis(trifluoromethanesulfonyl)imide, NaTFSI) and ionic liquid (N-butyl-N-methylpyrrolidiuium bis(trifluoromethanesulfonyl)imide, Py14TFSI) for the NIBs. The solid ceramic electrolyte is the main part(>80wt%) and small amount of ionic liquid remain at the surface of solid ceramic. It was observed that the ceramic particles in the composite electrolyte provided the main path ways for ion mobility, and the ionic liquid was used to reduce interfacial resistance between solid-solid ceramic particles. This new type of composite electrolyte has a solid electrolyte shape in the form of a film without leakage of liquid electrolyte and cathode, electrolyte film is assembled by phase inversion method. The total thickness of cathode-electrolyte assembled film is about 100µm and there is no leakage of liquid electrolyte so it can be bipolar stacked in single cell. We used Na1.0Li0.2Ni0.25Mn0.75O2 cathode material which demonstrated modest electrochemical performance at 3.5V vs. Na/Na+ and structural stability for reversible Na intercalation reaction. By using this cathode material, we demonstrate composite electrolyte cell system working that Na/composite electrolyte/Na1.0Li0.2Ni0.25Mn0.75O2 half-cell shows good cycle performance to 50cycle as 80mAh/g and impressive electrochemical stability of 6V. Also, this composite cell system shows superior thermal stability than organic liquid electrolyte. Further, we demonstrate bipolar stacked in single coin cell so 8V class single coin cell can be made. From these result, this composite electrolyte cell system can solve the interfacial resistance between solid electrolyte and it is quite promising be used for high voltage batteries.
2:45 PM - ES04.03.05
Operando Study of Carbon Electrode Degradation Mechanisms at Electrode/Electrolyte Interface in Water-Based Electrochemical Capacitors
Krzysztof Fic 1 , Minglong He 2 , Erik Berg 2 , Elzbieta Frackowiak 1 , Petr Novák 2
1 , Poznan University of Technology, Poznan Poland, 2 , Paul Scherrer Institut, Villigen Switzerland
Show AbstractThis paper reports on the operando study of activated carbon electrode degradation mechanisms in water-based electrolytes (1 mol L-1 Li2SO4 and LiNO3 solutions).
In order to present more in-depth insight into the interfacial processes, the electrochemical investigations have been supported by on-line electrochemical mass spectrometry (OEMS) and in-situ Raman spectroscopy. The discussion of the results will demonstrate that the electrode performance fade might have a different origin, although the electrochemical response in various electrolytes is similar. Briefly, for capacitor operating with 1 mol LiNO3 solution it has been observed that NO3- specimen seems to be reactive with a carbon electrode, essentially at high potentials values. Moreover, the oxidation of the electrode by NO3- appeared to be reversible with incremental capacitance increase. Furthermore, the hydrogen generation on the negative electrode plays a protective role for both electrodes, neutralizing tentatively generated O-based radicals and preserving the electrode surface against oxidation. On the other hand, both in-situ Raman spectroscopy and OEMS techniques proved the evolution of CO2, NO2, and NO gasses.
A detrimental effect of oxygen evolution at elevated voltages (up to 1.8 V) has also been observed. An in-depth study involving the implementation of the operando techniques also allowed the most optimal voltage for both systems to be determined, taking into account their long-term performance as well. Finally, the results obtained proved that similar electrochemical response of the carbon electrodes, essentially in terms of performance fade, may have a various origin and requires a different approach for further development.
ES04.04: Stability Challenges
Session Chairs
Cengiz Ozkan
Xueliang Sun
Monday PM, November 27, 2017
Hynes, Level 3, Ballroom A
3:30 PM - *ES04.04.01
Controlling Interfaces for Stable Metal Anodes and Sulfur Cathodes
Cary Pint 1
1 Department of Mechanical Engineering and Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee, United States
Show AbstractIn this talk, I will discuss key advances from my group focused on controlling the nanoscale surfaces and interfaces of electrode materials in order to engineer stable electrochemical operation. I will first discuss results aimed toward the development of stable and controllable sulfur cathodes for lithium-sulfur batteries, where controlled polar interfaces in carbon-based host cathodes can control and mitigate polysulfide shuttling effects that compromise cathode stability. Utilizing atomic layer deposition of V2O5, a polar material with the greatest binding affinity for soluble polysulfides, onto the surface of a sulfur-infiltrated carbon nanotube (CNT) host at controlled submonolayer thickness, our work demonstrates a correlation between cathode stability and sulfur utilization that dictates overall device performance and provides mechanistic insight into the widely-discussed polysulfide anchoring mechanism. Next, I will transition to demonstrating how interfaces in sulfur-containing 2-D MoS2 nanostructures can modulate their performance in lithium batteries. Our findings conclude that graphene-like carbon layers stacked onto MoS2 nanosheets not only improves the electrochemical stability of these materials, but can also control conversion energetics. Controlled studies and in-situ characterization indicate that small amounts of interface strain present at stacked 2-D material interfaces can steer electrochemical reaction pathways to be more favorable for cell-level electrode integration. Finally, I will discuss our recent results in sodium metal anodes where controlled nucleation layer interfaces of different materials formed on an Al collector material can control nucleation overpotential, Coulombic efficiency, and energy efficiency. Our work demonstrates 99.9% anode Coulombic efficiency enabled by controlled nucleation layers, which we demonstrate is required to develop full cell designs based on metal anodes. Overall, our work demonstrates how controlling electrochemical processes at electrode-electrolyte interfaces can overcome critical limitations in battery systems with improved energy density, stability, and controllability.
4:00 PM - ES04.04.02
Thermal Stability of Different LixVOPO4 Cathodes
Hui Zhou 1 , Jia Ding 1 , Wenqian Xu 2 , Yong Shi 1 , Fredrick Omenya 1 , Natalya Chernova 1 , M. Stanley Whittingham 1
1 , SUNY Binghamton, Vestal, New York, United States, 2 , Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractLiVOPO4 is one type of attractive high energy cathode materials for lithium-ion batteries, which can utilize two redox couples of V4+/V5+ and V3+/V4+ at around 4.0 and 2.5 V, and give a theoretical capacity > 300 Ah/kg and energy density > 1000 Wh/kg, much higher than conventional intercalation cathodes. There are a number of polymorphs of LiVOPO4 three of which have verified structures of symmetry triclinic, orthorhombic and tetragonal, which are also known as e, b and a. All three have demonstrated the ability to reversibly intercalate more than one lithium ion. However, due to the similar structure of them, the thermal stability of each phase is not fully understand.
Our recent study found that different LiVOPO4 phases can be synthesized in different temperature ranges with same precursors and phase transformation can happen between them with heating and cooling. To better understand the thermal stability of the different LiVOPO4 polymorphs and detailed phase transformation progress between them, we specially performed in-situ high temperature X-ray diffraction (XRD) at APS for different LiVOPO4 samples. These results will be presented together with other thermal study results from DSC and TGA. In addition, the chemical lithiated products for each sample, i.e. different Li2VOPO4, were also thermally studied by in-situ high temperature XRD and the thermal stability of them will also be discussed. This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under Award No. DE-EE0006852.
4:15 PM - ES04.04.03
Interfacial Instability of Amorphous LiPON against Lithium and LiCoO2
Karsten Albe 1 , Sabrina Sicolo 1
1 , TU Darmstadt, Darmstadt Germany
Show AbstractThe chemical instability of the glassy solid electrolyte LiPON against metallic lithium and LiCoO2 as well as the occurrence of side reactions at both interfaces is investigated by means of electronic structure calculations within density-functional theory [1,2]. Using an evolutionary structure search followed by a melt-quenching protocol, a model for the disordered structure of LiPON is generated. Static optimization of a simple Li-LIPON interface model suggest that the diffusion of lithium into LiPON is driven by a considerable driving force. Calculated reaction energies indicate that the reduction and decomposition of LiPON is thermodynamically favorable. A simple defect level scheme is proposed, which allows to predict interface stabilities based on point defect formation energies. The direct comparison between UV photoelectron spectroscopy measurements and calculated electronic densities of states for increasing stages of lithiation univocally identifies the new phases as Li2O, Li3P and Li3N. These products are stable against Li metal and form a passivation layer which shields the electrolyte from further decomposition while allowing for the diffusion of Li ions.
[1] S. Sicolo, K. Albe, J. Power Sources 331, 382-390 (2016).
[2] S. Sicolo, M. Finger, R. Hausbrand, K. Albe, 354,124–133 (2017)
4:30 PM - ES04.04.04
Interfacial Charge Transfer between Lithium Storage Material and Redox Mediators Measured by Scanning Electrochemical Microscopy
Ruiting Yan 1 , Jalal Ghilane 2 , Hyacinthe Randriamahazaka 2 , Qing Wang 1
1 , National University of Singapore, Singapore Singapore, 2 , Université Paris 7 - Denis Diderot, Paris France
Show AbstractDeveloping a clear picture of the kinetics of LiFePO4/ FePO4 delithiation/ lithiation is significant in disclosing the material’s potential in high-rate electrochemical application. Most electrochemical methods use LiFePO4/ FePO4 mixed with conductive additives, while kinetic parameters detected by chemical reaction with pure LiFePO4/ FePO4 is difficult to reach the scale of interfacial level. Here, we measured the interfacial charge transfer kinetics of LiFePO4/ FePO4 chemically delithiated/ lithiated by redox shuttle molecules using the feedback mode of scanning electrochemical microscopy(SECM). Effective rate constants keff between 2.35 ~ 6.57 10-3 cm/s are extracted under irreversible substrate kinetics model. Linear dependency of keff on x in “xLiFePO4/(1-x)FePO4” dual-phase verifies the measured kinetics limited by surface reaction. Local chronoamperometry experiment provides evidence disproving “shrinking core” model for LiFePO4/ FePO4 transition mechanism. By introducing this methodology, we provide a solid approach for the general studies on interfacial charge transfer kinetics of various poorly conductive lithium storage materials in different environments with high sensitivity, potentially a guiding light for material and redox mediator optimization in real electrochemical application.
4:45 PM - ES04.04.05
3D Spongy Graphene as a Novel Electrode Architecture for Electrochemical Energy Storage
Nageh Allam 1
1 , American University in Cairo, New Cairo Egypt
Show AbstractA simple method is demonstrated to prepare spongy adenine-functionalized graphene (SFG) as interconnected, porous 3-dimensional (3D) network crinkly sheets. Such 3D network structure provides better contact at the electrode/electrolyte interface and facilitates the charge transfer kinetics. The fabricated SFG was characterized by X-ray diffraction (XRD), FTIR, scanning electron microscopy (FESEM), Raman spectroscopy, thermogravimetric analysis (TGA), UV−vis absorption spectroscopy, and transmission electron microscopy (TEM). The synthesized materials have been evaluated as supercapacitor materials in 0.5 M H2SO4 using cyclic voltammetry (CV) at different potential scan rates, and galvanostatic charge/discharge tests at different current densities. The SFG electrodes showed a maximum specific capacitance of 333 F/g at scan rate of 1 mV/s and exhibited excellent cycling retention of 102% after 1000 cycles at 200mV/s. The energy density was 64.42 Wh/kg with a power density of 599.8 W/kg at 1.0 A/g. Those figures of merit are much higher than those reported for graphene-based materials tested under similar conditions. The observed high performance can be related to the synergistic effects of the spongy structure and the adenine functionalization.
ES04.05: Poster Session I
Session Chairs
Tuesday AM, November 28, 2017
Hynes, Level 1, Hall B
8:00 PM - ES04.05.01
In Situ Electrochemical Coating of MgF2 on LiCoO2 for Lithium-Ion Batteries
Jungwoo Lim 1 , Aram Choi 1 , Kyu Tae Lee 1
1 School of Chemical and Biological engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractLithium ion batteries have been considered as a promising energy storage device for electric vehicles. However, the energy density of the present lithium ion batteries does not meet the demands of electric vehicles that require more than 500 km of travel per charge. Therefore, LiCoO2 has recently been revisited to increase the charging voltage above 4.55 V (vs. Li/Li+), leading to an increase in reversible capacity. However, electrolyte decomposition is severe at above 4.4 V (vs. Li/Li+), resulting in poor cycle performance. Various surface coatings of cathode materials were introduced to alleviate electrolyte decomposition at high voltages, which exhibited the improved electrochemical performance. [1] Although the previous surface coating methods have shown promise, most coating techniques cannot achieve a conformal coating of thin protective layers, except for the atomic layer deposition requiring complex processes and high cost.[2] As a result, the inhomogeneous coating on LiCoO2 still causes severe electrolyte decomposition at above 4.55 (V vs. Li/Li+).
In this presentation, we demonstrate a facile in situ electrochemical coating method to obtain thin and uniform coating layers. Electrolyte additives in the form of an inorganic salt are oxidatively decomposed with the electrolyte on the LiCoO2 surface during cycling, thus leading to the formation of uniform coating films on the LiCoO2 surface. The formation mechanism of coating layers on the cathode surface is similar to that of solid electrolyte interphase (SEI) layers on the anode surface. We clarify the formation mechanism of the coating layer on the LiCoO2 surface through various ex situ analyses. Mg-based inorganic salts were examined as an additive for the surface coating, resulting in the formation of uniform MgF2 films on the LiCoO2 surface. In addition, we evaluated the electrochemical performance of LiCoO2 with Mg-based additives. LiCoO2 electrochemically coated with MgF2 films exhibited stable cycle performance over 60 cycles in the high voltage range of 3.00 - 4.55 V (vs. Li/Li+). Moreover, we clarify the failure mechanism of LiCoO2 in the high voltage range and elucidate the role of the MgF2 film for the improved electrochemical performance.
1. Lee, K. T.; Jeong, S.; Cho, J., Roles of Surface Chemistry on Safety and Electrochemistry in Lithium Ion Batteries. Accounts of Chemical Research 2013, 46 (5), 1161-1170.
2. Kalluri, S.; Yoon, M.; Jo, M.; Park, S.; Myeong, S.; Kim, J.; Dou, S. X.; Guo, Z.; Cho, J., Surface Engineering Strategies of Layered LiCoO2 Cathode Material to Realize High-Energy and High-Voltage Li-Ion Cells. Advanced Energy Materials 2017, 7 (1), 1601507-n/a.
8:00 PM - ES04.05.02
Functionalized Graphene-Polyoxometalate Nanodots Assembly as “Organic-Inorganic” Hybrid Supercapacitors and Advanced Electrochemical Microscopy
Sanju Gupta 1 , Bryce Aberg 1
1 , Western Kentucky University, Bowling Green, Kentucky, United States
Show AbstractThe development of next-generation stable and high-performance electrodes consisting of pseudocapacitive polyoxometalates (phosphomolybdate acid-H3PMo12O40; POM and phosphotungstic acid-H3PW12O40; POW) and supercapacitive reduced graphene oxide (rGO) synthesized hydrothermally is reported. The rGO and POM (and POW) nanodots interactions create emergent materials and "organic-inorganic" hybrid supercapacitors enabled by bridged (covalent/electrostatic) tailored interfaces and tunable physicochemical properties. The concomitant combination of double-layer capacitance from rGO and redox (faradaic) POM (and POW) led to an intrinsic increase in specific capacitance from 70 F.g−1 (rGO) to 320 F.g−1 (hybrids) and excellent stability (~94% retention). Scanning electrochemical microscopy is used to to gain insights into physico-chemical processes and to determine heterogeneous electron transfer rate highlighting roles of graphene edge plane sites in combination with mapping electrochemical (re)activity and electroactive site distribution. The findings are attributed to mesoporous network and topologically multiplexed ionic and conductive pathways provided by graphene with localized pockets of re-hybridized orbitals contributing toward rapid charge transfer. This work is supported in parts by NSF-MRI, KY NSF EPSCoR and KY NASA EPSCoR Grants.
8:00 PM - ES04.05.03
Flexible Micro–Supercapacitors Based on Flash Light Irradiation of Graphene Oxide
Yusik Myung 1 , HoSeok Lee 1 , SungHoon Jung 1 , TaeYoung Kim 1
1 Department of Bionano Technology, Gachon University, Seongnam Korea (the Republic of)
Show AbstractWe fabricate graphene based flexible micro–supercapacitors using flash light irradiation. Flash light irradiation was applied to rapidly convert graphene oxide into graphene and to form an open networks of graphene. By flash light irradiation with a prepatterned mask, graphene microelectrodes were directly patterned onto a thin film of graphene oxide and graphene based micro–supercapacitors were fabricated on them. The resulting flash light irradiated graphene was then tested as electrode materials for electrochemical capacitors. The electrochemical performance of the electrodes will be presented in terms of volumetric capacitance, energy density and power density.
8:00 PM - ES04.05.04
Li Insertion and Interstitial Transport in Perovskite Oxides
Yifei Sun 1 , Shriram Ramanathan 1
1 Materials Engineering, Purdue University, West Lafayette, Indiana, United States
Show AbstractNi containing oxides in the perovskite phase such as rare-earth nickelates possess interesting electronic structure properties depending on the occupancy of their d-orbitals. The electronic and ionic conductivity have a complex interplay depending on the spatial variation of the Ni-site valence. This is due to combination of non-degeneracy in the d-orbitals due to crystal field splitting compounded with strong electron repulsion. Lithium doping of such oxides is an early stage field of study with implications in both design of ionic conductors for energy storage and understanding fundamentals of electrochemical charge transfer between dopants and host oxide lattice. We will present studies involving Li-ion doping from liquid electrolyte based half-cells into nickelate perovskite and corresponding changes to the electronic transport. We will discuss dynamics of lithium intercalation and direct monitoring with evolution of the electrical conductivity. Further, we will present a comparison of structural changes during the doping process to conductivity relaxation. Pristine SmNiO3, NdNiO3 and EuNiO3 films grown by physical vapor deposition show resistivity of ~5, 0.5 and 4 mΩ cm respectively. After lithiation for two hours, the resistivity of all thin films exhibit colossal change to 107, 105 and 106 mΩ cm, respectively with corresponding changes to optical absorption. We will correlate kinetics of charge transfer at liquid-perovskite interfaces across the rare-earth nickelate series with A-site steric effects and phase metastability.
8:00 PM - ES04.05.05
Synthesis of Highly Conductive PEDOT:PSS for All-Organic Flexible Supercapacitors
Haruki Saito 1 , Hidenori Okuzaki 1
1 , Yamanashi University, Kofu Japan
Show AbstractWe have succeeded in fabricating all-organic flexible supercapacitors by synthesis of highly conductive poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) as both polarization and collector electrodes. The PEDOT:PSS with a composition ratio of 1:2.5 was synthesized at various polymerization temperatures. It was found that electrical conductivity of the PEDOT:PSS film increased with decreasing the polymerization temperature (Tp) and the value reached as high as 1145 S/cm at Tp = 0 °C, which was higher than that of the most conductive commercial PEDOT:PSS (Clevios PH1000, Heraeus). This is probably due to the higher molecular weight and/or crystallinity of the PEDOT molecules.
Furthermore, all-organic flexible supercapacitors consisting of a separator containing ionic liquid ([EMI][TFSI])/propylene carbonate as an electrolyte sandwiched between the two PEDOT:PSS films as polarization and collector electrodes. The electrical properties of the supercapacitors were evaluated by charging/discharging and cyclic voltammetry methods. Surprisingly, without activated carbons and metal collector electrodes, the PEDOT:PSS films worked as supercapacitors capable of charging/discharging at the electric double-layer. In order to clarify the mechanism in more detail, electrical properties of the all-organic flexible supercapacitors with different compositions between the PEDOT and PSS were investigated. The PSS was partly removed from the PEDOT:PSS electrode by dipping in ethylene glycol, which decreased weight fraction of PSS from 74 to 61 wt%. On the other hand, electrical conductivity increased because weight fraction of the PEDOT increase from 26 to 39 wt%. The internal resistance and capacitance of the supercapacitors were less dependent on the PSS, which clearly demonstrated that the PEDOT played a predominant role for charging/discharging at the electric double-layer. Indeed, the specific capacitance increased by 40% with increasing the PEDOT. Moreover, the all-organic flexible supercapacitors were stable without degradation of performance even after 100,000 cycles.
8:00 PM - ES04.05.06
Silicon-Carbon Nanotube Aerogel Nanostructures for Lithium-Ion Batteries with Long-Cycle Life and High Capacity
Hyungcheoul Shim 1 2 , Ilhwan Kim 1 3 , Chang-Su Woo 1 , Seungmin Hyun 1
1 Department of Applied Nano-Mechanics, Korea Institute of Machinery & Materials (KIMM), Daejeon Korea (the Republic of), 2 Department of Nanomechatronics, University of Science and Technology (UST), Daejeon Korea (the Republic of), 3 School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon Korea (the Republic of)
Show AbstractSilicon is a cathode material for lithium ion secondary batteries, which is attracting attention due to its high specific capacity compared to conventional graphite. However, the volume expansion about 300% or more in the case of lithiation may deteriorate battery life because of delamination from the current collector and destruction between electrode materials.
In this study, to solve these problems, we have introduced carbon nanotube aerogels into silicon anode fabrication. A carbon nanotube aerogel having a large number of pores is fabricated by using the freeze drying method, and silicon is deposited thereon by using a sputtering process, thereby constructing a structure resistant to deterioration due to volume expansion.
As a result, the carbon nanotube aerogel/silicon composite exhibited high discharge capacity retention of 70% or more during about 1,000 charge/discharge cycles when applied to an anode material of a lithium ion secondary battery. In addition, the excellent electrical conductivity and high specific surface area of the carbon nanotube aerogels compensate for the low electrical conductivity of the silicon, thereby contributing to the improvement of the rate characteristics as well as enhancing the diffusion characteristics of lithium ions, thereby enhancing the electrochemical performance as a whole.
8:00 PM - ES04.05.07
The Effect of the Electrode/Separator Integration Using Water-Based Ceramic Coating Slurry for Lithium-Ion Batteries
Hyunkyu Jeon 1 , Junyoung Choi 1 , Dahee Jin 1 , Danoh Song 1 , Seok Woo Kim 1 , Jinkyu Park 1 , Yong Min Lee 2 , Myung-Hyun Ryou 1
1 Department of Chemical & Biological Engineering, Hanbat National University, Daejeon Korea (the Republic of), 2 Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology, Daejeon Korea (the Republic of)
Show AbstractGenerally, the volume expansion of the electrodes after repeated charging and discharging processes causes the physical separation between the electrodes and separators. This is an important factor in reducing cycle life of lithium-ion batteries (LIBs). Introducing an adhesive polymer coating layer between the electrode and the separator may be a promising approach for tightly integrating them.
To fabricate the adhesive polymer coating layer, non-polar organic solvent-based polymer coating slurry is prerequisite because of super hydrophobic surface property of polyolefin-based microporous separators. In general, organic solvents are toxic and expensive, requiring additional recovery facilities. This can increase total production costs [1,2]. Furthermore, the organic solvent can dissolve the polymeric binder of the electrodes and cause the morphological change of the electrodes. The adhesive polymer coating layer should be thin and porous because a thick and non-porous structure of polymer film can also result in poor cycle performance of LIBs by blocking the porous structure of the electrodes and separators [3].
Herein, by using a surfactant, we were able to produce an adhesive polymer coating layer on the polyethylene (PE) surface using an aqueous coating slurry. In addition, Al2O3 ceramics were used to form a porous structure. Similarly, we coated the surfactant-assisted aqueous Al2O3 coating slurry on both electrodes and assembled with separators to produce an integrated electrode/separator. We investigated physical properties of integrated separator/electrode assembly, including their thermal stabilities, ionic conductivity, and air permeability. And, electrochemical properties of integrated separator/electrode assembly were investigated. The integrated separator/electrode assembly exhibited superior cycle performance in unit cells (LiMn2O4/graphite) compared to control case without integration.
References
[1] M. H. Ryou et al., A water-based Al2O3 ceramic coating for polyethylene-based microporous separators for lithium-ion batteries, Journal of Power Sources, 2016, 315, 161-168.
[2] M. H. Ryou et al., Plasma-assisted water-based Al2O3 ceramic coating for polyethylene-based microporous separators for lithium metal secondary batteries, Electrochimica Acta, 212, 649-656.
[3] M. H. Ryou et al., Effects of an integrated separator/electrode assembly on enhanced thermal stability and rate capability of lithium-ion batteries, ACS Applied Materials & Interfaces. 2017, 9, 17814-17821.
8:00 PM - ES04.05.08
Investigating the Interphase Formation on Solid Lithium-Ion Conductors by Neutron Reflectometry
Manuel Weiß 1 , Daniel Schröder 1 , Wolfgang Zeier 1 , Juergen Janek 1
1 Institute of Physical Chemistry, Justus Liebig University, Giessen Germany
Show AbstractMost of currently available lithium-ion and related battery systems are based on liquid electrolytes as those achieve high ionic conductivity and fast interface kinetics. They allow, however, the transport of other ions besides Li+ which results in degradation and reduced cyclability. Thus, hybrid battery concepts consisting of different solid and liquid electrolytes might be needed for next-generation systems in order to suppress these unwanted effects. This introduces additional interfaces, though, about whose transport kinetics only little is known yet.
We show that the combination of the solid electrolyte LAGP (Li1.3Al0.3Ge1.7(PO4)3) and liquid ether-based electrolytes results in the formation of a solid-liquid electrolyte interphase (SLEI) which adds an energy barrier to the system higher than that for ionic transport in the solid electrolyte. The temporal evolution of this interphase is analyzed by time-dependent in-situ electrochemical impedance spectroscopy (EIS), as well as ex-situ X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), revealing an increase of the interface resistance over time[1].
This phenomenon is also found to be present when using LiPON (lithium phosphorous oxide nitride) thin films instead of LAGP. In order to obtain information about the temporal evolution of the SLEI thickness and to correlate this with the resistance increase over time, in-situ periodic neutron reflectometry measurements are performed, as they are able to resolve volume fraction profiles of lithium on the interface.
[1] M. R. Busche, T. Drossel, T. Leichtweiss, D. A. Weber, M. Falk, M. Schneider, M.-L. Reich, H. Sommer, P. Adelhelm, J. Janek, Nat. Chem. 2016, 8, 426.
8:00 PM - ES04.05.09
Metal Nitrides for Electrochemical Ammonia Synthesis in Molten Chlorides
Tim Sudmeier 1 , Ian McPherson 1 , Edman Tsang 1
1 , University of Oxford, Oxford United Kingdom
Show AbstractAmmonia is one of the most traded chemicals in the world with over 131 million tons (2010) being synthesized each year.1 Currently, the Haber-Bosch process is employed to produce ammonia requiring high temperature and pressure1. In addition H2 from steam reformation is used making it a major sources of CO2 pollution1,2. A promising alternative for small scale applications is electrochemical ammonia production utilizing molten salts as electrolytes.2 Such systems work at ambient pressure, moderate temperature and can use renewable hydrogen sources like water enabling small local production of ammonia for energy storage and as building block chemical for fertilizer synthesis.2
Few materials have been evaluated as electrocatalysts for ammonia synthesis in molten salts, mainly transition metals.2 Metal nitrides, especially Co3Mo3N, are highly active in classical ammonia synthesis with a Mars-van-Krevelen-type mechanism being suggested as the mechanism at play.3 Recently, computational studies have suggested using metal nitrides as electrocatalysts for ammonia formation assuming a similar mechanism.4
In this work, we explore the possibilities of using more complex gas electrode materials in alkali chloride melt to increase the rate and current efficiency of electrochemical ammonia synthesis. Furthermore, we hope to gain a deeper understanding of the mechanism of nitrogen reduction and more generally ammonia formation in molten salts. We synthesized several ternary metal nitrides using temperature-programmed nitridation of oxide precursor and characterized them by powder XRD, BET, XPS, UV-Vis, SEM, TEM and SQUID. Furthermore, the stability of the nitride phase in the chloride melt was tested and the necessary conditions to inhibit decomposition were optimized. A range of electrochemical tests (CV, amperometry, etc.) were carried out and XPS, as well as SEM were used to monitor compositional and structural changes on the surface. Finally, metal nitride electrodes were used for nitrogen reduction.
References
1. Lan, R.; Irvine, J. T. S.; Tao, S. Sci. Rep. 2013, 3.
2. Giddey, S.; Badwal, S. P. S.; Kulkarni, A. Int. J. Hydrogen Energy 2013, 38 (34), 14576.
3. Zeinalipour-Yazidi, C. D.; Hargreaves, J.S.J; Catlow, R.A., T. J. Phys. Chem. C. 2015, 119 (51), 28386-28376.
4. Abghoui, Y.; Skúlasson, E. Procedia Computer Science 2015, 51, 1897.
8:00 PM - ES04.05.10
High-Performance Lithium-Sulfur Dioxide Batteries Exploiting Conventional Carbonate-Based Electrolytes
Hyeokjun Park 1 , Hee-Dae Lim 1 , Hyung-Kyu Lim 2 , Hyungjun Kim 2 , Kisuk Kang 1
1 , Seoul National University, Seoul Korea (the Republic of), 2 , Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of)
Show Abstract: Shedding new light on conventional primary batteries sometimes inspires new chemistry adoptable for rechargeable batteries. Recently, a primary lithium-sulfur dioxide battery, which offers a high energy density and a long shelf-life, was successfully renewed as a promising rechargeable system exhibiting significant merits over the lithium-oxygen chemistry such as small polarization and good reversibility.1 Here, we demonstrate, for the first time, that the reversible operation of the lithium-sulfur dioxide battery is also possible exploiting conventional carbonate-based electrolytes. Even though the carbonate-based electrolytes possess advantages such as high ionic conductivity and good electro/chemical stability and have thus been widely used in commercial lithium ion batteries, they could not be used in metal-air batteries due to the serious side reactions.2,3 Theoretical and experimental studies reveal that the SO2electrochemistry is highly stable in the carbonate-based electrolytes enabling the reversible formation of Li2S2O4 in contrast to lithium-oxygen batteries. The use of the carbonate-based electrolyte leads to the remarkable enhancement of power and reversibility with much improved compatibility with lithium metal; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves the outstanding cycle stability over 450 times with 0.2 V polarization, which is one of the highest efficiencies reported for metal-gas batteries. This study highlights the potential promise of rechargeable lithium-sulfur dioxide chemistry along with the viability of the conventional carbonate-based electrolytes in metal-gas rechargeable systems.
Reference
Lim. H. -D. et al. Ange. Chem. 127, 9799 (2015).
Freunberger, S. A. et al. J. Am. Chem. Soc. 133, 8040 (2012).
Kim. J. et al. Phys. Chem. Phys. Chem. 15, 3623 (2013).
8:00 PM - ES04.05.11
Natural Gel Derived Hard Carbon as an Anode for Sodium-Ion Batteries
Neha Sharma 1 , Yogesh Gawli 2 , Absar Ahmad 2 , Musthafa Muhammed 1 , Satishchandra Ogale 1
1 , Indian Institute of Science Education and Research (IISER) Pune, Pune, GA, India, 2 , National Chemical Laboratory, Pune, Maharashtra, India
Show AbstractAmong the numerous anode materials for Na ionbattery, hard carbon is recognized to be a good anode material for Na-battery. In this work, we present the interesting case of hard carbon obtained from a natural gel derived from the commonly used Basil seeds (Osimum Basilicum, which swell 30 times their weight by absorbing water) by freeze-drying and controlled pyrolysis. This hard carbon has sheet-like and tubular morphology with decorated surface defects attributed to the presence of oxygen functionalities. The hard carbon shows a low surface area of 40 m2g-1 which is the characteristic feature of a hard carbon. It offers a very low charge transfer resistance for the ion mobility as evident from the impedance spectroscopy study. The cyclic voltammogram shows the insertion de-insertion redox peaks at around 0.01V. A good reversible capacity of 195 mAh g-1 at 0.1 A g-1 with an impressive ~91% retention of initial capacity after 300 cycles is realized. Importantly, it sustains high current densities with not much drop in the capacity value. The hard carbon is able to sustain very high current densities and delivers 95 mAh g-1 at 2 A g-1. Thus, the natural gel derived hard carbon performs much better than commercial hard carbon.
8:00 PM - ES04.05.12
Microporous Nitrogen-Doped Carbon Synthesis through Direct Carbonization of Covalent Organic Frameworks
Tomohiro Shiraki 1 2 , Gayoung Kim 1 , Jun Yang 2 , Naotoshi Nakashima 2
1 Department of Applied Chemistry, Kyushu University, Fukuoka Japan, 2 WPI-I2CNER, Kyushu University, Fukuoka Japan
Show AbstractPorous carbons are gathering great attention for various applications such as gas separation, energy conversion, and energy storage. Moreover, the incorporation of nitrogen atoms in carbon networks (N-doping) was found to increase capacitive performance owing to pseudocapacitance[1] and to affect electronic states of the adjacent carbons which efficiently create the active sites for oxygen reduction reaction (ORR).[2] Recently, it was reported that micropores play an important role to enhance electrochemical functionalities.[3] So far, microporous carbons have typically been prepared through the activation processes of carbonaceous materials or via template syntheses, and new synthetic methods that allow us to fabricate structurally-controlled microporous carbons are desired toward further functional improvement.
Recently we reported N-doped carbon formation through carbonization using covalent organic frameworks (COFs) that have molecularly-ordered porous network structures.[4] Herein, we report the fabrication of microporous N-doped carbons by direct carbonization of an azine bond-linked COF (ACOF1) and their electrochemical capacitive performance.
ACOF1 was synthesized by a solvothermal method using benzene-1,3,5-tricarboxaldehyde and hydrazine monohydrate. The obtained ACOF1 was then carbonized at 800 °C for 3 h under nitrogen gas flow.
The XRD pattern of the obtained ACOF1 shows obvious diffraction peaks that are assignable to crystalline facets of ACOF1. After carbonization of ACOF1, in the Raman spectrum, two peaks appear at around 1300 cm-1 and 1590 cm-1, which are attributed to D and G bands of graphitic carbon structures. In addition, from the XPS measurements for N1s, it was found that the carbonized ACOF1 has nitrogen-doped graphitic structures. Based on the BET analysis in N2 gas adsorption measurements, the specific surface area of ACOF1 and the carbonized one are estimated to be 1168 m2g-1 and 1596 m2g-1, respectively. Moreover, the pore size with a diameter of 0.68 nm is selectively formed in the carbonized ACOF1. From these results, we confirm that microporous N-doped carbon can be fabricated through carbonization of ACOF1.
The capacitive behaviors of the carbonized ACOF1 was investigated by electrochemical measurements, in which the specific capacitance of the carbonized ACOF1 is 234 Fg-1 at the 1.0 Ag-1.
Therefore, our approach would be promising to fabricate various microporous N-doped carbons and to develop advanced electrochemical materials for supercapacitors and fuel cell catalysts.
References
[1] Lu, Y. et al., J. Nanosci. Nanotechnol. 2014, 14, 1134. [2] Yu, D. et al., J. Phys. Chem. Lett. 2010, 1, 2165. [3] Yushin, G. et al., J. Am. Chem. Soc. 2010, 132, 3252. [4] Shiraki, T. and Nakashima, N. et al., Chem. Lett. 2015, 44, 1488.
8:00 PM - ES04.05.13
Applying Dual Redox Mediators for Rechargeable Non-Aqueous Mg-O2 Batteries
Qi Dong 1 , Xiahui Yao 1 , Jingru Luo 1 , Dunwei Wang 1
1 , Boston College, Brighton, Massachusetts, United States
Show AbstractAs a post-Li-ion energy storage technology, rechargeable non-aqueous Mg-O2 battery features high volumetric energy density (up to 6264 Wh/L based on the formation of MgO and 4762 Wh/L based on the formation of MgO2), good safety (dendrites free) and low cost. However, existing reports of Mg-O2 operation suffer low round-trip efficiency and poor rechargeability. It was found that superoxide formation (which features an equilibrium potential 2.04 V) and the passivation of Mg anode lead to the low discharge potential, while the difficulties in decomposing MgO and/or MgO2 electrochemically are responsible for the problems for recharge. Here we employ an approach to address these challenges. To facilitate the formation of MgO and MgO2, which are desired for high discharge potentials, we applied 1,4-benzoquinone (BQ) as a discharge redox mediator that induces O2 reduction by avoiding superoxide intermediate formation. An overpotential reduction of 0.3 V was measured. To decompose the oxide compounds upon recharge, we used 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (Co(II)TPP) as a recharge redox mediator that assists in O2 evolution, and measured a recharge overpotential decrease around 0.3 V. Importantly, the two redox pairs are compatible in the same DMSO-based electrolyte and functionalize separately to enable reversible formation and decomposition of the MgO and MgO2. These results prove the efficacy of adopting dual redox mediators to enable rechargeable Mg-O2 battery operations and open up a new door toward further development of this promising electrochemical energy storage technology.
8:00 PM - ES04.05.14
Role of Defects and Edge Sites in the Ion-Transport Mechanism of Few-Layer Graphene Electrodes
Madeline Stark 1 , Kaci Kuntz 1 , Hailey Kim 1 , Scott Warren 1
1 , University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
Show AbstractIntercalation compounds of bulk layered materials, such as graphite, black phosphorous, and molybdenum disulfide, have been widely explored as electrodes for electrochemical energy storage. Recently, their 2D counterparts have emerged as candidates for ultrathin battery applications due to their unique electronic properties near the atomic limit. These materials readily intercalate with a variety of ions and the intercalated materials demonstrate significant enhancements in conductivity, transparency, and energy storage which make them attractive electrode materials for a variety of applications. In order to develop sustainable energy storage devices however, it is critical to understand the mechanisms of ion transport and degradation that occur at the interface of these 2D layered electrodes. The presence of edge sites and grain boundaries are of particular interest, since they present a likely pathway to initiate intercalation. Defects within the layers can also lead to degradation and non-uniform charging of the material. However, the role that edges, grain boundaries, and defects play in the mechanism of ion transport between the layers of 2D materials is not-well understood. Here we present our results on the fundamental process of intercalation within the few-layer graphene (FLG)-bisulfate system. Intercalation of bisulfate into FLG can be reversibly cycled, closely paralleling current battery technology, but in an aqueous medium. In order to provide insight into the physical and chemical changes that occur within the thin graphite flakes, we have developed a planar battery set-up that allows us to perform various in-situ measurements during intercalation. Qualitatively, we image the electrochemical intercalation process under an optical microscope and observe surface oxidation, deformation, and degradation of the material with quantitative galvanostatic cycling. This technique allows us to visualize intercalation at edges and grain boundaries to observe whether intercalants preferentially insert themselves at these sites. To correlate the optical images with a quantitative depiction of charge transfer, we perform in-situ Raman spectroscopy at edges and grain boundaries. By imaging at distinct locations during the intercalation, we determine how the degree of charge transfer varies from the edges to the interior of a flake. In addition, our observation of strain-induced interference fringes that result from ions intercalating between the layers of FLG allows us to develop a model that provides information on the thickness and chemical composition of intercalated flakes at diffraction-limited resolution. Our model is generalizable to other systems and could be integrated with spatially-resolved in-situ characterization techniques, such as XRD, Kelvin Force Microscopy, and Magnetic Force Microscopy to offer further insight into the staging and degradation processes that occur in these materials.
8:00 PM - ES04.05.15
2D All-Solid-State Fabric Supercapacitor Fabricated via an All Solution Process for Use in Smart Textiles
Yunseok Jang 1 , Jeongdai Jo 1 , Kwangyoung Kim 1
1 , Korea Institute of Machinery & Materials (KIMM), Daejeon Korea (the Republic of)
Show AbstractSmart textiles have attracted considerable attention for their ability to extend the functionality and utility of common fabrics. Smart textiles are defined as textile products, such as fibers, filaments, and yarns, together with woven, knitted, or non-woven structures, which can interact with the environment/user and provide some other functionality.1 Most smart textiles in existence today include a variety of embedded electronic components (such as electronic chipsets, sensors, wires, batteries, etc.) that are rigid and generally incompatible with standard apparel. The rigid components introduce wearability and reliability problems into these garments. Recent efforts have been applied toward developing more flexible electronic components.2
Y. Cui et al proposed simple method to fabricate the textile supercapacitor by dipping textile into the carbon nanotubes (CNT) solution. CNT can act simultaneously as electrodes and current collectors due to their relatively high conductivity compared to other electrode materials.3 The use of CNT as current collectors, however, is limited due to the relatively high resistivity of CNT compared to metal-based current collectors. Other weaknesses of these devices include the three-dimensional (3D) sandwich structure employed in traditional energy devices. A 3D sandwich structure presents several drawbacks when included in integrated circuits compared to two-dimensional (2D) planar structures because a 2D planar structure can be simultaneously prepared with other circuit units.
In this study, we propose a method that overcomes the drawbacks of CNT-based energy textiles, such as their low conductivity and the 3D sandwich structure, by using silver (Ag) nanoparticles (NP) ink, an intense pulsed light (IPL) sintering system, and a simple spray patterning system. The Ag NP current collectors displayed a higher conductivity than the CNT current collectors. However, compared to CNT current collectors, the heat treatment temperature of Ag NP current collectors is too high to be used on textile substrate. (i.e., a temperature of 150 °C or more which causes heat damage to the textile substrate) IPL sintering systems can reduce the sintering temperature of Ag NP and prevent thermal damage to textiles during the Ag NP sintering process. The spray patterning technique is very useful for preparing printed electronics because it is a very simple, fast, and low-cost process. We propose a simple combination system for overcoming the problems associated with CNT current collectors by using Ag NP, an IPL sintering system, and a spray patterning system.4
References
1. M. Stoppa, A. Chiolerio, Sensors 14, 11957 (2014).
2. J. F. Gu, S. Gorgutsa, M. Skorobogatiy, Appl. Phys. Lett. 97, 133305 (2010).
3. L. Hu, M. Pasta, F. L. Mantia, L. Cui, S. Jeong, H. D. Deshazer, J. W. Choi, S. M. Han, Y. Cui, Nano Lett. 10, 708 (2010).
4. Y. Jang, J. Jo, K. Woo, S. -H. Lee, S. Kwon, K. -Y. Kim, D. Kang, Appl. Phys. Lett. 110, 203902 (2017).
8:00 PM - ES04.05.16
Toward Simple and Scale-Up Method by Hierarchical Mesoporous Carbon Nanosphere Additives for Electrochemical Performance in Li-S Batteries
Seong-Jun Kim 2 1 , Jungjin Park 2 3 , Yung-Eun Sung 2 1
2 Center for Nanoparticle Research, Institute for Basic Science, Seoul, Gwanak-gu, Korea (the Republic of), 1 School of Chemical and Biological Engineering, Seoul National University, Gwanak-gu, SE, Korea (the Republic of), 3 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractRecently, the need for large-scale power sources have been raised globally due to the depletion of fossil fuel and the development of electric vehicles (EVs). Among the promising candidates for next generation batteries, sulfur has been highlighted as an alternative cathode materials because its theoretical gravimetric and volumetric energy are 2500 Wh kg-1 and 2800 Wh L-1, respectively. However, the low electronic and ionic conductivity and the solubility of polysulfide intermediates play a decisive role in the disruption of hindrance of conventional use. To solve these problems, previous study focused on the composing of typical mesoporous carbon structure, in which sulfur has easily infiltrated. That can effectively prevent the irreversible loss of soluble polysulfide and improve high utilization of sulfur. However, this frame has the limitation of restricted loading space of sulfur. In this study, we have introduced hierarchical mesoporous carbon derived by wrinkled silica template using chemical vapor deposition (CVD), for simple and large-scale synthesis for practical applications. Moreover, this mesoporosity provides excellent electrochemical performance of Li-S batteries by its role of additives. We hope that this research will support a wide use of lithium sulfur batteries.
8:00 PM - ES04.05.17
Phosphorus Incorporated Microporous Carbon for Stable Li-Ion Battery
Yogesh Gawli 1 , Malik Wahid 1 , Manjusha Shelke 1 , Satishchandra Ogale 2
1 , National Chemical Laboratory, Pune India, 2 Physics, Indian Institution of Science, Education and Research, Pune, Maharashtra, India
Show AbstractWe demonstrate that pyrolysis of phytic acid renders activated (micro-porous) and phosphorus-incorporated carbon in a single-step process. The phosphate groups of the phytic acid play a dual role of porogen and act as a source of the heteroatom, P. A maximum surface area of 1400 m2/g is obtained after pyrolysis at 1100 OC. X-Ray diffraction illustrated the enhancement in the degree of graphitization with the increase in the pyrolysis temperature. The Id/Ig ratio calculated from the Raman Spectroscopy was noted to be proportional to the pyrolysis temperature. X-ray photoelectron spectroscopy confirmed the presence of P=O, acting as protrusions on the surface. As an anode material for Li-ion battery, the optimized material exhibited a reversible capacity of 750 mAh/g. Potentiostatic electrochemical impedance spectroscopy indicated lowering of charge transfer resistance for the case of the higher temperature pyrolyzed sample. The optimized material showed a cyclic stability of 1000 cycles at high current of 5 A/g.
8:00 PM - ES04.05.18
Lithium Titanate Confined in Carbon Nanopores for Asymmetric Supercapacitors
Enbo Zhao 1 , Chuanli Qin 2 , Hong-Ryun Jung 1 , Gene Berdichevsky 3 , Alper Nese 3 , Seth Marder 1 , Gleb Yushin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 , Heilongjiang University, Harbin China, 3 , Sila Nanotechnologies, Inc., Alameda, California, United States
Show AbstractAs one of the superior anode materials for high power Li-ion batteries and asymmetric supercapacitors, spinel Li4Ti5O12 (LTO), has attracted significant attention in recent years owing to its unique characteristics.[1] Li4Ti5O12 exhibits a flat lithiation potential plateau at the voltage of ~1.55 V vs. Li/Li+, which largely prevents both excessive solid electrolyte interphase (SEI) formation and lithium dendrite growth. In addition, LTO is known for its “near-zero” volume change during repeatable lithiation and delithiation, which contributes to its excellent cyclic stability.
One major drawback of LTO to be qualified for high-rate performance is its poor electrical conductivity. One approach to improving electrical conductivity is doping of metal or nonmetal ions in Li, Ti or O sites, though the cyclic stability may be impaired and the resulting rate performance may still be insufficient for practical applications. Another drawback is that the Li-ion transport in LTO is slow compared with that of supercapacitor electrode materials. [2] Therefore, recent endeavors have been devoted to the design of LTO nanostructures and those with porous LTO morphologies, which demonstrated improved kinetics. The synthesis of LTO nanoparticles has been extensively studied, however, it is still rather difficult to prepare uniform Li4Ti5O12 nanoparticles of small dimensions (e.g., < 5-10 nm) due to the high annealing temperature required during synthesis (700-800 oC), at which LTO crystals aggregate and over-grow due to Ostwald ripening.
In this research, we report on a novel facile strategy for the low-cost synthesis of uniform Li4Ti5O12- activated carbon nanocomposites (LTO-AC), where crystalline sub – 4 nm LTO nanoparticles are uniformly distributed in the nanopores of the carbon matrix.[3] In contrast to the nanosized particles of various shapes and sizes, which are difficult (and expensive) to handle and utilize in electrodes, micro-scale LTO-AC has the potential to serve as drop-in replacement for AC in supercapacitor electrode production. AC not only serves as spatial confinement to control the growth of LTO nanocrystals, but also as a conductive material to compensate the poor electrical conductivity of LTO. As a result, Li4Ti5O12 nanoparticles in AC pores demonstrated remarkable performance characteristics, showing more than 100 mA h g-1 at the ultra-high rate of 350C (1C= 175 mA g-1), where charge or discharge takes place in ~6 s. When compared with pure AC, the LTO-AC nanocomposites showed up to 12 times higher gravimetric capacity and 12 times higher volumetric capacity.
[1] K. Zaghib, A. Mauger, H. Groult, J. Goodenough, C. Julien, Materials 2013, 6, 1028.
[2] N. S. Choi, Z. H. Chen, S. A. Freunberger, X. L. Ji, Y. K. Sun, K. Amine, G. Yushin, L. F. Nazar, J. Cho, P. G. Bruce, Angewandte Chemie-International Edition 2012, 51, 9994.
[3] E. Zhao, C. Qin, H.-R. Jung, G. Berdichevsky, A. Nese, S. Marder, G. Yushin, ACS Nano 2016, 10, 3977.
8:00 PM - ES04.05.19
Application of β-MnO2/N-Containing Graphene Composite to Flexible Asymmetric Solid-State Supercapacitor
Hsin-Ya Chiu 1 , Chun-Pei Cho 1
1 , National Chi Nan University, Nantou County Taiwan
Show AbstractIn this work, the composite of manganese oxide (MnO2)-modified nitrogen (N)-containing graphene was obtained by a low-cost hydrothermal method. It was used as the active material to fabricate the negative electrode of flexible solid-state asymmetric supercapacitors. The MnO2 growing on the N-containing graphene sheets was of β-phase and strip-like structure. The results of FTIR, Raman and XPS spectra proved the presence of Mn-O bondings and the N and Mn elements in the composite. A membrane with the PVA/LiCl electrolyte gel was employed as the separator between two electrodes. Compared to the supercapacitors without containing MnO2, the one with the composite of MnO2-modified N-containing graphene exhibited a more vertical slope in the low-frequency region of the Nyquist plot. This indicated that β-MnO2 was favorable to reduced internal series resistance and thereby enhanced charge transfer. It was found that mass loadings on the electrode also affected the capacitor performance. A smaller specific capacitance was adversely caused when the mass loading was too high. After the calculations from the cyclic voltammetry (CV) curves were completed, a high specific capacitance of 209 F/g was obtained, while the energy density and power density were 442 Wh/kg and 1744 W/kg, respectively. Bending tests under the current density of 0.1A/g were also carried out. After more than 1000 bending cycles, the retention rate of specific capacitance was approximately 96 %. This demonstrated the good flexibility and cycling stability of our supercapacitors. The good capacitance performance was attributed to the synergistic effect of β-MnO2 and N-containing graphene. The composite of MnO2-modified N-containing graphene was verified to be a promising active material for flexible solid-state asymmetric supercapacitors.
8:00 PM - ES04.05.20
Fabrication of Mesoporous Electrodes for Lithium-Ion Capacitors Using Electrospraying
Yeonsong Kim 1 , Jihyun Yoon 1 , Ho-Sung Yang 1 , Ji ho Youk 2 , Woong-Ryeol Yu 1
1 Material Science Engineering, Seoul National University, Seoul Korea (the Republic of), 2 Advanced Fiber Engineering, Inha University, Incheon Korea (the Republic of)
Show Abstract
As high-end portable devices and electric vehicles come to market, there is a growing demand for more enhanced energy storage systems. Lithium ion capacitor (LIC) has emerged as a candidate for the solution because LIC can not only overcome the energy density limitation of conventional supercapacitor but also improve the power output of lithium ion batteries. Efficient electrode materials for LIC have been actively studied using metal components and mesoporous carbon to improve the energy density and the power density. Porous, especially mesoporous (more than 2nm, less than 50nm), materials are crucial to develop such electrode owing to large surface area. Conventional methods for manufacturing mesoporous materials, however, are less cost-effective, hazardous, and sensitive. In this research, a new method was developed to manufacture mesoporous materials using electrosparying, which is a simple and cost-effective process.
Mesoporous carbon cathode and metal-carbon hybrid anode were manufactured using poly (vinyl pyrrolidone) (PVP) and electrospraying. PVP was selected due to economic feasibility, low chemical toxicity, and good solubility in most organic solvents. PVP acted as not only mesoporous carbon precursor but also a capping agent with metal due to excellent physiological compatibility and good adhesion properties. Sacrificial polymer (styrene-acrylonitrile (SAN)) was mixed with PVP before electrospraying because it can form pores in PVP after heat treatment above 500 Celsius degree after electrosparying. Manufactured PVP nano-particles after heat treatment exhibited high surface area with mesopores applicable to cathode materials. The electrospraying method is being extended to manufacture metal-carbon particles. PVP and metal precursor are solvated and sprayed, followed by heat treatment. Hybridized particles are expected to demonstrate high energy density when used for anode material of LIC. Before electrochemical characterization, lithium pre-doping is carried out for lithium-intercalation into metal-carbon particles using an auxiliary lithium metal electrode. The electrochemical characteristics of mesoporous carbon cathode and metal-carbon hybrid anode will be presented in detail at the conference.
8:00 PM - ES04.05.21
A High-Performance Polyanion-Type Cathode Material NaVPO4F/C for Sodium-Ion Battery
Pingyuan Feng 1 , Wei Wang 1 , Kangli Wang 1 , Kai Jiang 1
1 , Huazhong University of Science and Technology, Wuhan China
Show AbstractPolyanion compounds, such as Na3V2(PO4)3 and NaVPO4F, are promising cathodes for sodium ion batteries (SIBs) because of their high structural stability, decent theoretical capacity and suitable redox potential.1 However, the polyanion-type electrodes always show poor electrochemical performance suffering from the inherent low electronic conductivity. The properties of NaVPO4F is still under exploration, while a lot of methods, such as coating with conductive materials, increasing the porosity, and doping with other ions, are applied for the preparation and modification of NaVPO4F composite.2-6 Herein, a type of high-performance NaVPO4F/C with 3D coral-like porous architecture is reported. Such unique structure is advantageous for increasing the interface area between the electrode and electrolyte, preventing NaVPO4F particles from aggregating, and enabling fast diffusion of Na-ion and transferring of electrons. The NaVPO4F/C composite shows excellent electrochemical performance of high capacity (103 mAh g-1 at 2 C and 100 mAh g-1 at 5 C), excellent cyclability (99 mAh g-1 after 320 cycles at 1 C and 79 mAh g-1 after 2500 cycles at 5 C) and outstanding rate performance (95 mAh g-1 at 20 C). The above results indicate that the as-prepared NaVPO4F/C is a promising cathode of SIB for energy storage applications.
Acknowledges: The authors greatly acknowledge the financial support from National Natural Science Foundation of China (No. 21405053), the Specialized Research Found for the Doctoral Program of Higher Education of China (No. 20130142120036) and the National Thousand Talents Program of China.
References:
1. T. Jin, Y. Liu, Y. Li, K. Cao, X. Wang and L. Jiao, Advanced Energy Materials, 2017, 1700087.
2. J. Barker, M. Y. Saidi and J. L. Swoyer, Electrochemical and Solid-State Letters, 2003, 6, A1.
3. Y. Lu, S. Zhang, Y. Li, L. Xue, G. Xu and X. Zhang, Journal of Power Sources, 2014, 247, 770-777.
4. Y. Ruan, K. Wang, S. Song, X. Han and B. Cheng, Electrochimica Acta, 2015, 160, 330-336.
5. M. Xu, C. Cheng, Q. Sun, S. Bao, Y. Niu, H. He, Y. Li and J. Song, RSC Adv., 2015, 5, 40065-40069.
6. Z. Liu, X. Wang, Y. Wang, A. Tang, S. Yang and L. He, Transactions of Nonferrous Metals Society of China, 2008, 18, 346-350.
8:00 PM - ES04.05.22
Understanding the Role of Hydrofluoroethers in Solvate Electrolytes and Its Effect on Electrochemical Performance of the Li−S Battery
Minjeong Shin 1 , Heng-Liang Wu 1 , Andrew Gewirth 1
1 , University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractWith an increasing demand for electric vehicles and portable electronics, Li−S batteries have received great attention as a promising next generation battery due to its high energy density and the low cost of sulfur. The major problem that hinders the commercialization of the Li−S battery lies in the complicated reduction/oxidation pathway of the Li−S chemistry. High-order lithium polysulfide intermediates readily dissolve into the organic electrolyte, causing severe capacity fading and poor Coulombic efficiency. In addition, the migration of intermediate polysulfides to the Li metal anode causes the well-known polysulfide shuttle effect. Recently, a new class of electrolyte called "solvate" with high concentrations of salt has been explored due to its sparingly solvating properties towards polysulfides. Despite these beneficial effects, the solvate electrolytes exhibit high viscosity and low ionic conductivity compared to the conventional 1 M ethereal electrolytes. The transport properties of the solvate complexes were improved by the addition of a low-viscosity cosolvent. Hydrofluoroether (HFE) was used as a cosolvent owing to its nonsolvating property towards polysulfides and miscibility with the solvate solutions. Nazar and co-workers evaluated the solvate electrolyte for Li−S battery, based on high concentration LiTFSI salt in acetonitrile (MeCN) to form the solvate (MeCN)2−LiTFSI, reporting that the addition of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) cosolvent produces better capacity retention compared to the neat solvate. The HFE cosolvent has a significant effect on the local solvation structure of the electrolyte and the Li−S cell cyclability. Here, we evaluate four HFE cosolvents with varying degrees of fluorination to determine the effect of HFE addition on the electrochemical performance of the Li−S battery. Galvanostatic cycling experiments show that the addition of highly fluorinated HFEs yields higher discharge capacity relative to cells with less fluorinated HFE cosolvents. Raman and NMR spectroscopy show that HFEs with higher degree of fluorination coordinates to Li+ at the expense of MeCN coordination, producing relatively higher free MeCN content in solution. The electrolytes with higher free MeCN facilitate S8 reduction kinetics at the cathode interface likely resulting in improved cycling of the Li−S cell. In addition, the solvate electrolytes diluted with highly fluorinated HFEs exhibit lower polysulfide solubility resulting in cleaner Li metal anodes with fewer polysulfide byproducts. This work provides the design rules for developing advanced solvate electrolyte which is sparingly solvating with respect to polysulfides while maintaining reactivity at the cathode.
Reference:
Cuisinier, M.; Cabelguen, P. E.; Adams, B. D.; Garsuch, A.; Balasubramanian, M.; Nazar, L. F., Unique behaviour of nonsolvents for polysulphides in lithium-sulphur batteries. Energ Environ Sci 2014, 7 (8), 2697-2705.
8:00 PM - ES04.05.23
Enhanced Electrochemical Performance of High Energy Cathode Material LiVOPO4 Coated with Lithium Borate Oxide Glass Layer
Yong Shi 1 , Hui Zhou 1 , Hanlei Zhang 2 , Linda Wangoh 3 , Fredrick Omenya 1 , Natasha A. Chernova 1 , Guangwen Zhou 2 , Louis Piper 3 , M. Stanley Whittingham 1
1 Chemistry and Materials Science and Engineering Program, Binghamton University, Vestal, New York, United States, 2 Department of Mechanical Engineering & Materials Science and Engineering Program, Binghamton University, Binghamton, New York, United States, 3 Department of Physics, Applied Physics and Astronomy, Binghamton University, State University of New York, Binghamton, New York, United States
Show AbstractThe high energy cathode material LiVOPO4 suffers low conductivity property and the side reactions between delithated VOPO4 and electrolyte, which seriously hinder the electrochemical performance. A high ionic conducting glass lithium borate oxide, Li2O-2B2O3, was successfully coated on the surface of LiVOPO4 in this work. The glass coating layer greatly increases lithium ion diffusion and suppresses SEI layer forming on the surface of LiVOPO4. The improved kinetic properties give a better electrochemical reversibility, rate capability and higher discharge capacity of LiVOPO4 with ~250 mAh g-1 cycling at C/5.
This project is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under Award No. DE-EE0006852.
8:00 PM - ES04.05.24
High Performance Carbon Supercapacitor Electrodes Derived from a Triazine-Based Covalent Organic Polymer with High Microporosity
Minjae Kim 1 , Seokhoon Jang 1 , Eunbeen Na 1 , Sang Eun Shim 1
1 Department of Chemistry and Chemical Engineering, Inha University, Inchoen Korea (the Republic of)
Show AbstractHighly microporous carbon materials were produced by carbonization of a triazine-based covalent organic polymer (COP) followed by carbonization and CO2 physical activation. The N-containing porous COP was prepared from easily available economic monomer precursors via a simple Friedel-Crafts reaction, which produced a predominantly microporous structure with a high surface area. Carbonization at 600−900 °C produced predominantly microporous carbons with a narrow pore size distribution in the range of 0.5−1.5 nm. Upon further activation using CO2, more micropores were formed, accompanied by an increase in the surface area (to 2003 m2 g-1) and the nitrogen level in the carbon structure was maintained at ca. 2 wt.%. The electrochemical properties of the samples were measured by employing a three-electrode system with 6 M KOH electrolyte. Among the prepared carbon samples, the electrode fabricated using the carbon activated at 900 °C (AC-900) had a specific capacitance of 278 F g-1 at a current density of 1 A g-1, which is significantly higher than that of a commercial activated carbon (130 F g-1) and ranks among the highest reported so far. This improved performance was attributed to the highly microporous structure of the nitrogen-doped carbon with a narrow pore size distribution.
Acknowledgement
This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (grant number: NRF-2015R1A4A1042434).
Symposium Organizers
Cengiz Ozkan, University of California, Riverside
Ali Coskun, Korea Advanced Institute of Science and Technology
Ekaterina Pomerantseva, Drexel University
Federico Rosei, Université du Quebec
ES04.06: In Situ Characterization and Operando Techniques I
Session Chairs
Cary Pint
Ekaterina Pomerantseva
Tuesday AM, November 28, 2017
Hynes, Level 3, Ballroom A
8:00 AM - *ES04.06.01
Probing the Interfaces and Interphases of All-Solid-State Batteries through Time-of-Flight Secondary Ion Mass Spectroscopy
Marina Leite 1
1 , University of Maryland, College Park, College Park, Maryland, United States
Show AbstractAll-solid-state batteries represent a promising alternative to energy storage devices. Nevertheless, spatially resolving where Li preferentially accumulates during cycling can elucidate critical open questions in the field, related to the undesired chemical reactions that cause capacity fade. We realize time-of-flight secondary ion mass spectroscopy (ToF-SIMS) in oxygen free and controlled environment to map the spatial distribution of Li-ions in all-solid-state batteries formed by Si/LiPON/LiCoO2, a model system. We determine Li spatial distribution within all active layers of the batteries upon cycling, and deconvolute Li diffusion from the formation of a solid-electrolyte interphase (SEI) at the LiPON-LiCoO2 interface after the first lithiation step. We corroborate the ToF-SIMS results with in situ surface analysis of the chemical and morphological changes that take place during charging/discharging. We find >92% of capacity retention after 100 cycles and 98% of Coulombic efficiency. We foresee ToF-SIMS becoming a widely used characterization method to image Li spatial distribution in energy storage systems, proving invaluable insights related to the formation of SEIs.
8:30 AM - ES04.06.02
Operando Cross-Sectional State-of-Charge Mapping of Lithium-Ion Battery Cathode Materials via a Novel Test Cell Design
Jeffrey Ovens 1 2 , Stephen Campbell 2 , Byron Gates 1
1 , Simon Fraser University, Burnaby, British Columbia, Canada, 2 , Nano One Materials Corp., Burnaby, British Columbia, Canada
Show AbstractEfforts to improve the performance of lithium ion batteries have significantly increased in recent years, resulting from their ubiquitous use in portable electronics, and the prospect of their use in electric vehicles and household energy storage solutions. Such improvements have typically come in the form of new, or modified cathode materials (or the syntheses thereof) exhibiting higher specific capacities and greater stability for long term use. In recent years, it has been recognized that to direct future improvements there is a need to more deeply understand the material transformations and ion transport processes occurring during electrochemical cell cycling. To this end, in situ and operando structural and spectroscopic characterization techniques have begun to be a focus of new research activities. Though mostly still new to the field, such techniques have proven their value in increasing the general understanding of charge and discharge processes within battery materials. To date, all such techniques probe the active material in the plane of the current collector – i.e. while 2-D data collection is possible within this plane, no data is collected as a function of distance from the current collector. Such information is important not only because it can give insight into ion transport and SEI formation processes, but also because it provides simultaneous access to the microscopic (solid-liquid, solid-solid) interfaces, as well as to information on the cathode-separator-anode interfaces. Thus, presented herein is a novel operando test cell design, which allows for probing active lithium ion materials by cross-sectional analysis in real time during electrochemical cycling as described above. The utility of this unique cell design is demonstrated through a state-of-charge analysis and mapping of commercially available cathode materials. Of particular interest in this study is the state-of-charge as a function of distance from the current collector. While several models and indirect studies have been done to this end, this represents the first direct observation of this property during cell operation.
8:45 AM - ES04.06.03
In Situ Equipment Condition Monitoring of Lithium-Ion Cells by Fiber Optical Sensor Systems
Alexander Graefenstein 3 , Julian Schwenzel 3 , Antonio Nedjalkov 1 , Jan Meyer 2
3 Electric Energy Storage, Fraunhofer IFAM, Oldenburg, Niedersachsen, Germany, 1 Fiber Optical Sensor Systems, Fraunhofer HHI, Goslar, Niedersachsen, Germany, 2 , TU Clausthal, Goslar, Niedersachsen, Germany
Show AbstractThe safety of battery-based energy storage devices is an important topic and has brought a significant increase in research activity in the fields of additives for electrolytes and new cell materials during the past decade. However, major safety issues persist, whose hazardous potential like fire, explosion and release of toxic gases increase in a non-linear manner with continuously higher storage sizes and faster performed charge and discharge profiles. By contrast, large storable energy quantity and high retrievable performance are crucial factors for broad acceptance of the technology.
In the research work that will be presented, innovative fiber optical sensors are developed which enable an in-situ detection of additional safety parameters and thus lead to a further safety enhancement of battery systems. These photonic sensors can be placed directly inside the cell, either in between the single electrode layers or between the stack and the pouch bag foil. The hereby measurable status parameters are e.g. cell-internal changes in the electrolyte composition as well as strain and temperature variations. The sensors can be combined with the battery management system (BMS) of lithium-ion-cells to generate a higher impact of critical information and thus higher safety in operation.
First investigations proved the ability to integrate fiber optical sensors into pouch bag cells. The cells were cycled for more than 1000 times and subsequently compared with cells without integrated photonic sensors. Even though post mortem analysis pointed out some small differences between the layer conditions, however, there was no measurable negative influence on the cell performance during cyclization. The detection of electrolyte composition changes while cycling was proven by using self-produced 5 Ah NMC/graphite cells with integrated fiber optical sensors and suggest a correlation between electrolyte alternations and critical health status of the cell. Due to that, noticeable cells can be optically identified and switched off prematurely, before they become safety critical. The usage of this technology therefore promises a significant reduction in the occurrence of hazardous situations.
9:00 AM - ES04.06.04
In Operando Surface Analysis of SEI Formation in Solid Electrolytes
Kevin Wood 1 , Steven Harvey 1 , K. Xerxes Steirer 2 , Shriram Santhanagopalan 1 , Chunmei Ban 1 , Se-hee Lee 3 , Glenn Teeter 1
1 , National Renewable Energy Laboratory, Ann Arbor, Michigan, United States, 2 , Colorado School of Mines, Golden, Colorado, United States, 3 , University of Colorado Boulder, Boulder, Colorado, United States
Show AbstractAs global energy consumption continues to grow rapidly, scalable, safe and cost-effective energy-storage strategies are becoming increasingly important. One widely studied approach for improving the safety of next generation batteries is through use of solid-state electrolyte (SSE) materials paired with Li metal anodes. Unfortunately, many promising SSE materials are unstable against metallic Li, resulting in degradation at the SSE/Li metal interface, typically creating a large interfacial impedance that can severely compromise battery performance. Therefore, understanding how these interfaces decompose and evolve during cycling is essential. Most current approaches to understanding these interfaces rely on ex situ analysis, but in situ and in operando measurement schemes are playing increasingly important roles. Unfortunately, ex situ measurements can suffer from artifacts associated with the extreme reactivity of Li metal and many SSE materials; and many existing in situ and in operando techniques require complex cell designs and/or access to specialized facilities; such as synchrotrons. Here, we report on the development of novel in operando measurement techniques for studying solid-state electrochemical interfaces such as the Li/SSE solid electrolyte interphase (SEI) using conventional laboratory-scale XPS and TOF-SIMS instrumentation. Through application of the ‘virtual current collector’ approach, (in which low-energy electrons are injected into or extracted from the free surface) we demonstrate electrochemical cycling of a Li/SSE/Li symmetric cell while monitoring in real time compositional and chemical changes of the SEI. Results demonstrate the formation of an SEI at the interface between Li3PS4 (LPS) and metallic Li during the first charge cycle. Analysis of these XPS spectra reveal a layered SEI structure that contains phases including LixP, Li2S, LiOH, and Li2O. Subsequent charge/discharge cycles reveal compositional and phase evolution, and provide evidence of stable vs. unstable SEI components. This type of understanding is critical for rationally designing solutions to create stable interfaces that will enable next-generation battery technologies.
9:15 AM - ES04.06.05
In Situ Measurements of State of Charge Dependent Mechanical Properties of Cathode Films
Insun Yoon 1 , Jay Sheth 1 , Pradeep Guduru 1
1 , Brown University, Providence, Rhode Island, United States
Show AbstractLithium Manganese oxide (LMO), a canonical spinel-structured lithium ion battery cathode material, undergoes mechanical degradation originating from lithium insertion/extraction-induced internal stresses. Evolution of mechanical properties such as elastic constants and fracture toughness as a function of the degree of lithiation are fundamental information to accurately model degradation mechanisms. Although there have been atomistic calculations, there is paucity of measurements owing to experimental challenges. We report in situ measurements of thin film (~30nm) LMO elastic modulus, stress, and volume evolution during electrochemical cycling. A free-standing membrane consisting of current-collector/LMO layers is fabricated and assembled into a custom electrochemical cell which allows pressurization of the membrane. The cell is integrated into an atomic force microscope (AFM) to measure the resulting membrane deflection. From the relation between the applied pressure and maximum deflection, elastic modulus and residual stress of the LMO layer are extracted. A current-collector/LMO step is fabricated on a separate sample to measure the volume change. The LMO films are galvanostatically cycled to different potential values to understand the influence of lithium content on the mechanical properties. The LMO Volume evolution measurements reveal an irreversible volume decrease of approximately 9% during the first cycle and cyclic 2-3% volume changes due to lithium insertion/extraction from the second cycle. The cyclic volume change agrees with reported lattice parameter change measure by X-ray diffractometry. We measure the plane strain modulus of as-prepared LMO to be approximately 165 GPa which decreases by ~15% during the first cycle. The elastic modulus change is cyclic from the second cycle with ~20% decrease during lithium extraction. These measurements suggest the importance of accounting for the elastic modulus dependence on the state of charge in modeling the internal stress field in cathode particles.
9:30 AM - ES04.06.06
The Role of Iodide on the Formation of Lithium Hydroxide in Lithium-Oxygen Batteries
Michal Tulodziecki 1 , Chibueze Amanchukwu 1 , David Kwabi 1 , Yu Katayama 2 , Graham Leverick 1 , Fanny Barde 3 , Paula Hammond 1 , Yang Shao-Horn 1
1 , MIT, Cambridge, Massachusetts, United States, 2 Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto Japan, 3 , Toyota Motor Europe, Zaventem Belgium
Show AbstractLithium–air batteries can potentially offer three times the gravimetric energy of commercial Li-ion batteries.1 Unfortunately, the poor reversibility and kinetics of lithium-oxygen (Li-O2) chemistry in aprotic electrolytes remains a critcal challenge, that limits its practical use. One of the main problems related to Li2O2 precipitation is its insulating nature, Li2O2 precipitate passivates the electrode surface hindering further electron transfer.2
Recently, soluble redox (RM) mediators have been shown to promote the kinetics of charge transfer.3 The operation of RM relies on the electro-chemical oxidation of the mediator, which itself in a second step chemically decomposes the Li2O2. An obvious advantage of RM is that, thanks to their solvation, they are able to reach the discharge product Li2O2 even if this one is not in contact with the current collector. In particular, lithium iodide RM have been shown to greatly lower the charging overpotential and improve cycle life.4,5 However, ambiguities exist in terms of the effect of LiI on the reversibility of electrochemical reduction of oxygen in presence of lithium ions (Li+, O2 redox chemistry) and battery cyclability.6-8 Some studies have shown high reversibility of Li-oxygen chemistry with LiI upon prolonged cycling4,5 while others report poor reversibility and efficiency due to the formation of LiOH6-8. The role of iodide and mechanistic details regarding the formation of LiOH are not understood, which is critical to assess if LiI can be used as a redox mediator to promote the kinetics of Li-O2 batteries.
In this presentation, we will discuss in detail the discharge mechanism of lithium-oxygen batteries with ether-based electrolyte containing LiI redox mediator; combining UV-Vis, Raman, FTIR, XRD, SEM and NMR characterization techniques. The effect of Li2O2 morphology and type (chemical versus in electrochemical), as well as the influence of water content were studied and will be discussed.9 We show that LiI facilitates the deprotonation of H2O by strong oxidants such as Li2O2 and/or LiO2, which results in the formation of LiOH instead of Li2O2 in an ether-based electrolyte. H2O deprotonation is promoted by the consumption of product H2O2 by oxidation of iodide to triiodide, and increased water acidity by strong I--H2O interactions as revealed by 1HNMR and FT-IR measurements. These two mechanisms, promoting LiOH formation mediated by LiI, relevant to the discharge of Li-O2 batteries, are novel and important to consider when developing LiI as the redox mediator for Li-air batteries.
[1]P. G. Bruce at al., Nat. Mater., 2011, 11
[2]P. Albertus at al., J. Electrochem. Soc., 2011, 158
[3]Y. H. Chen at al. , Nat. Chem., 2013, 5
[4]H. D. Lim at al., Angew. Chem. Int. Ed., 2014, 53
[5]T. Liu at al., Science, 2015, 350
[6]W. J. Kwak at al., J. Mater. Chem. A, 2015, 3
[7]C. M. Burke at al., ACS Energy Lett., 2016, 1
[8]V. Viswanathan at al., Science, 2016, 352
[9] M. Tulodziecki at al., Submited
9:45 AM - ES04.06.07
Interfacial Studies of Electrodes for Hydrogen Evolution—Nanoelectrical and Nanoelectrochemcial Imaging of Pt/Si Electrodes
Jingjing Jiang 1 , Zhuangqun Huang 2 , Chengxiang (CX) Xiang 1 , Rakesh Poddar 2 , Hans-Joachim Lewerenz 1 , Kimberly Papadantonakis 1 , Nathan Lewis 1 , Bruce Brunschwig 1
1 , California Institute of Technology, Pasadena, California, United States, 2 , Bruker Nano , Goleta, California, United States
Show AbstractIn Photoelectrochemical (PEC) water-splitting systems, the interfaces between the semiconductor and the catalysts are crucial. The interfaces should conduct electric charges, and bind the catalysts to light absorbers strongly. Pt/Si is a typical photocathode for hydrogen evolution reaction (HER), and electroless plating is a facile way to deposit Pt catalysts onto Si surfaces. Si photocathodes with electrolessly-deposited Pt nanoparticles (Pt-NP) show different electrical properties compared to that with evaporated Pt. When Si has SiO2, the adhesion between Si substrates and metal materials has been reported to be weak. This contribution investigates the electrical properties and mechanical adhesion of the interfaces in Pt-NP/p-Si electrodes on the nanoscale, using Atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM).
AFM studies show that the Pt nanoparticles deposited electrolessly have a highly-dispersed morphology, indicating the non-uniformity of this deposition method. Conductive AFM measurements in the air show that the Pt-NP/p-Si interface forms a rectified junction, and the Pt-NP/p+-Si interface forms an Ohmic junction. The contact currents of different Pt-NPs are not correlated with their topography, and only about half of the Pt-NPs showed measurable contact currents. The observed currents differ by 3 orders of magnitude between Pt-NPs. SECM measurements in an aqueous electrolyte have agreeable results that only a minority of the Pt-NPs showed conductance through the particle and the Si substrate.
The Pt-NPs showed strong adhesion to the Si surfaces in air. Even a stiff probe (with a nominal spring constant of 40 N/m) with large imaging forces (~μN) could not push most particles away. Only Pt-NPs with heights larger than 150 nm were subjected to pushing. However, the adhesion was substantially weakened in electrolyte. In aqueous electrolyte, a force less than 1/20 of that used in air could push the Pt-NPs away.
The above results suggest that the Pt-NP/Si photocathodes prepared by electroless deposition have highly dispersed Pt-NPs, and that less than half of the Pt-NPs can conduct high currents in air or in electrolyte. In addition, in aqueous electrolyte the adhesion of the Pt-NPs to the Si surface is dramatically weakened. These interfacial properties may be the reasons that limit the electrochemical performance of hydrogen evolution of Pt-NP/Si electrodes.
ES04.07: 2D Materials for Energy Storage
Session Chairs
Marina Leite
Cengiz Ozkan
Tuesday PM, November 28, 2017
Hynes, Level 3, Ballroom A
10:30 AM - *ES04.07.01
New 2D Electrodes for Li-Ion Battery Applications
Qingyu Yan 1 , Yu Zhang 1 , Dan Yang 1 , Zhongzhen Luo 1
1 , Nanyang Technological University, Singapore Singapore
Show Abstract
Li ion/Na batteries has shown great promises in various energy related applications. The performance of these energy storage devices can improved with strategized design and preparation of the electrode materials. We carried out works on growth of 2D structured cathode/anode material, including LiMPO4 (M=Fe, Ni, Co, Mn) and MPO4, and few layered black phosphorus by wet chemical processes. This type of materials is typical thin sheet structure with thickness of 2-5 nm and show promising Li/Na storage properties. For Olivine-type LiMPO4 (M = Fe, Mn, Co, Ni), we develop a liquid-phase exfoliation approach combined with solvothermal lithiation process in high-pressure high-temperature (HPHT) supercritical fluids for the fabrication of ultrathin LiMPO4 nanosheets (thickness: 3.7-4.6 nm) with exposed (010) surface facets. The diffusion of Li along [010] direction is particularly tuned through the thickness of the nanosheet due to the crystal orientation, which fasten the diffusion process. [1] For MPO4, we prepared ultra-thin two-dimensional (2D) nanoflakes, including FePO4, Mn3(PO4)2 and Co3(PO4)2, with highly ordered mesoporous structures in non-polar solvent. It is found that the as-obtained nanoflakes with thickness of ~3.7 nm are constructed from a single layer of parallel-packed pore channels. When tested as cathodes for lithium ion battery, they exhibits excellent stability and high rate capabilities. [2]. We also synthesis of few layered black phosphorus nanosheets through diferent methods and study their Li/Na storage properties. Especially, we try to improve their chemical stability by forming composite structures with the aid of spark plasma sintering (SPS) process. It shows that excellent air stabilityof SPS-processed black phosphorus can be achieved over the 60 days observation in maintaining its high Li storage properties. [3]
References:
[1] Xianhong Rui, Xiaoxu Zhao, Ziyang, Lu, Huiteng Tan, Daohao Sim, Huey Hoon Hng, Rachid Yazami, Tuti Mariana Lim, Qingyu Yan*, “Olivine-Type Nanosheets for Lithium Ion Battery Cathodes”, ACS NANO 7 (6), (2013), p5637-5646
[2] Dan Yang, Ziyang Lu, Xianhong Rui, Xiao Huang, Hai Li, Jixin Zhu, Wenyu Zhang, Yeng Ming Lam, Huey Hoon Hng, Hua Zhang,* Qingyu Yan*, “Synthesis of two-dimensional transition metal phosphates with highly ordered mesoporous structures for lithium-ion battery application”, Angewandte Chemie 53 (35), (2014), p9352-9355
[3] Yu Zhang, Huanwen Wang, Zhongzhen Luo, Hui Teng Tan, Bing Li, Shengnan Sun, Zhong Li, Yun Zong, Zhichuan J. Xu, Yanhui Yang, Khiam Aik Khor, Qingyu Yan*, “An air-stable densely packed phosphorene-graphene composite towards advanced lithium storage properties”, Advanced Energy Materials 6 (12), (2016), p1600453.
11:00 AM - ES04.07.02
Low Temperature Synthesis of 2D-Like Metal Carbides for Energy Storage Applications
Xining Zang 1 , Wenshu Chen 2 , Minsong Wei 1 , Lujie Yang 1 , Liwei Lin 1
1 , University of California, Berkeley, Berkeley , California, United States, 2 , Shanghai Jiao Tong University , Shanghai China
Show AbstractMetal carbides from the group 4, 5 and 6 transition metals are often described as the interstitial compounds which are refractory with metallic properties. It is well-known that some of these metal carbides have attractive energy-related properties, including catalytic activity, storage capability, stability and resistance to poisoning. In recent years, the focus has shifted to nanostructured metal carbides for large surface areas with improved energy performances, such as MXenes (2D transition metal carbide) materials providing eceptionally high specific capacitance.
Great amount of effort has been performed in developing new synthesis method, new structure, new composite to develop the full potential of 2D type transition metal carbides.Herein, we develop an easy and tolerant process to synthesis nanoscale Mo2C, WC and Co2C flake structures from a non-toxic hydrogel template. Hydrogel chains complex and drive the Mo5+/W6+/Co2+ ion to form layer-by-layer structure due to the triple helical nature of this polymer which has been demonstrated before in self-assemble processes. Solution of the metal ion-gelatin mixture is annealed at a relative lower temperature (600 oC) during which the self-healing property and salting out effect helps the formation of large scale carbide sheet structure while other polymer such as PVP and PEO tend to induce particles and aggregated structures. Residual solvent of H2O and alcohol help to generate high porous template during the severely boiling. Homogenous mono-phase carbide could be achieved from hydrogen mediated single precursor (Mo, W, Co), while precursor mixture of metal ions with various coordination bond strength with gelatin template can result in different heterogeneous structures. For example, the similar band structure and ligand field intensity of Mo and W ions dissolved in the gelatin solution can result in the uniform 2D sheets with the mixture phase of (Mo2C)x(W2C)y - implying potential syntaxic intergrowth.
Such synthesized 2D-like Mo2C and W2C provide high specific capacitance in lithium based electrolyte (50 F/g) and sulfuric acid electrolyte(40F/g). However, the highest specific capacitance is achieved in Mg2+ electrolyte (magnesium acetate), resulting up to 100F/g capacitance by scan rate of 1mV/s which also illustrate strongest intercalation with 2d-type Mo2C. Meanwhile, such carbide-Mg2+ electrolyte system could achieve a high working voltage range up to 2.4V due to low hydrolysis potential on carbide and stability of neutral electrolyte, resulting a significant energy density of 20Wh/kg.
11:15 AM - ES04.07.03
Electrochemical Exfoliation and Functionalisation of 2D-Materials for Energy Storage Devices
Andinet Aynalem 1 , Ian Kinloch 1 , Robert Dryfe 1
1 , University of Manchester, Manchester United Kingdom
Show AbstractElectrochemical exfoliation of graphite is considered to be a fast, scalable and eco-friendly way to produce graphene.[1, 2] Cathodic exfoliation in organic electrolyte, unlike anodic exfoliation, produces high quality graphene as it avoids the formation of oxygen containing functional groups.[2] However, development of applications of graphene is currently hampered by its poor dispersion in common, low-boiling point, solvents. In this contribution, we describe the single step simultaneous electrochemical exfoliation and functionalisation of graphene using diazonium compounds.[3] Using caesium salt (dissolved in dimethyl sulfoxide) the intercalating ions, functionalisation was achieved in combination with diazonium salt (either 4-nitrobenzenediazoniumtetrafluoroborate, 4 bromobenzenediazonium tetrafluoroborate or anthraquinone-1-diazonium chloride) as functionalisation moieties. We found that the presence of diazonium compounds in solution not only acts to functionalise the graphene but also aids the exfoliation through the generation of N2 gas which assists the separation of the functionalised graphene layers. The functionalisation also enhanced the dispersibility of graphene in aqueous solution by two orders of magnitude and increased the charge storage capacity of graphene by three times because of the introduction of surface active redox reactions (Figure 1). Finally, we will introduce a simple electrochemical route for the synthesis of metallic phase trilayer MoS2 nanosheets
Refernces (1) K. Parvez, R. J. Li, S. R. Puniredd, Y. Hernandez, F. Hinkel, S. H. Wang, X. L. Feng and K. Mullen, ACS Nano, 2013, 7, 3598-3606. (2) A. J. Cooper, N. R. Wilson, I. A. Kinloch and R. A. W. Dryfe, Carbon, 2014, 66, 340-350 and (3) D. W. Johnson, B. P. Dobson and K. S. Coleman, Current Opinion in Colloid & Interface Science, 2015, 20, 367-382.
11:30 AM - ES04.07.04
New Insights into Passivation of Nano-Sized Electrode Materials using Pure Graphene for Exceptional Stability and Activity
Chanhoon Kim 1 , Dong Sung Choi 1 , Sang Ouk Kim 1 , Il-Doo Kim 1
1 Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon Korea (the Republic of)
Show AbstractNanostructured materials have great scientific interests in a broad range of fields, including optics, catalysis, and energy conversion and storage technologies owing to their unique properties, which has not been discovered in bulk materials, stemmed from the confining in the nanoscale dimension and their extremely high surface to volume ratio. However, nanomaterials are vulnerable to coalescence, oxidation, and degradation due to their thermodynamically unstable and highly reactive nature. Thereby, the passivation of nanomaterials become more and more important to maintain their reliable properties from external environments. To stabilize nanomaterials, surface coating and wrapping by organic/inorganic materials have been widely investigated. Although entirely surrounded nanomaterials by passivation layer show remarkable stability and resistance to oxidation and degradation, the diverse applications of the nanomaterials diminish due to their attenuated activity. In the recent, owing to their excellent barrier property, the graphene is often used for stabilization and encapsulation of nanomaterials for protecting from external environments. Moreover, the new characteristics of graphene endowed by chemical doping or defect engineering can open up the new paths to enlarge diversity of its application combined with nanomaterials, which has rarely been reported.
In this work, we report new insights into utilizing highly monodispersed ultrasmall nanoparticles encapsulated in graphene as an active material with high stability and excellent activity for high performance lithium storages. Our simple and scalable strategy to synthesize highly monodispersed ultrasmall Co3O4 nanoparticles (~ 3.7 nm) discretely encapsulated in graphene, via simultaneous chemical vapor deposition (CVD) and subsequent in-situ oxidation at low temperature (180 °C) realizes both the highly stable and active characteristics. In-situ oxidation is a critical step in controlling the number of layers and defects of the graphene shell by catalytic oxidation and at the same time phase transformation of Co to Co3O4. By controlling of post oxidation conditions, highly monodispersed ultrasmall Co3O4 nanoparticles encapsulated by graphene shell with an appropriate number of layers, regarded as the desired and ideal structure for Li ion battery anode materials, were successfully synthesized. The graphene encapsulation significantly improves typical challenges of Co3O4 including huge volume expansion up to 300%, formation of unstable SEI layer, and poor electrical conductivity. This rationally designed electrode exhibits extremely confined volume expansion of only 15.8% at fully lithiated state and excellent electrochemical performances including highly stable capacity retention after 2000 cycles. More importantly, the it shows unprecedented rate performance which is far superior to previously reported Co3O4 based anodes.
11:45 AM - ES04.07.05
Contemporary Approach in Fanatical Slinky Two-Dimensional Nanomaterials for Electrochemical Energy Storage and Conversion Application
Kishwar Khan 1 , Sarish Rehman 2
1 Chemical and Biological Engineering (CBE), Hong Kong University of Science and Technology, Kowloon Hong Kong, 2 Department of Material Science, College of Engineering, Peking University, Beijing, Beijing, China
Show AbstractSince the invention of graphene by Noble Laurates in 2004, physicists Andre Geim and Konstantin Novoselov, research on this wonder 2D nanomaterial are grown progressively in the field of Condensed Mater Physics, Chemistry, Biology, Material Science, Medicine and Nanotechnology. Noting their attractive physical, chemical, electrical, mechanical, optical and numerous effective applications, in this contemporary review, we summarize the state of the art successive development of ultrathin two-dimensional nanomaterial with specific attention on their present advances. First, we will have a look on its introduction followed by the detail description of their composition and crystal structure. The miscellany of their preparation method is then illustrated, including insights on their advantages, and limitations, as well as some suggestions on proper characterization techniques. We also briefly discuss the detail usage of the ultrathin 2D nanomaterials for tremendous applications among electrocatalysis, batteries, and supercapacitors. In closing, the fortune demands, & perspectives in this sensational field are fledged on the basis of its present evolution.
References;
[1] Q. Li , R. Cao , J. Cho , G. Wu, Adv. Energy Mater. 2014, 4, 1301415.
[2] M. Gong, Y. Li, H. Zhang, B. Zhang, W. Zhou, J. Feng, H. Wang, Y. Liang, Z. Fan, J. Liub, H. Dai, Energy Environ. Sci., 2014, 7, 2025.
[3] W. Peng, Y. Li, F. Zhang, G. Zhang, X. Fan, Ind. Eng. Chem. Res. 2017, 56, 4611 −4626.
ES04.08: In Situ Characterization and Operando Techniques II
Session Chairs
Tuesday PM, November 28, 2017
Hynes, Level 3, Ballroom A
1:30 PM - *ES04.08.01
Enhancing Understanding of the Solid-Electrolyte Interface—Multi-Modal Characterization of Battery Systems
Karl Mueller 1 , Vijayakumar Murugesan 1 , Kee Sung Han 1 , Kristin Persson 2 , Nav Nidhi Rajput 2 , Nigel Browning 1 , B. Layla Mehdi 1
1 , Pacific Northwest National Laboratory, Richland, Washington, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractThe design and achievement of superior battery systems (i.e., those that are more efficient, higher in energy density, safer, more environmentally friendly, etc.) requires knowledge of fundamental chemical and physical properties of the system and its components while under operating conditions. Such advanced knowledge can be obtained through both modeling and experimental efforts. In the case of battery systems designed to replace the well-known lithium ion battery systems, new chemistries in particular are being explored and classified using state-of-the-art characterization and computational tools. Here we consider and explore the lithium-sulfur (Li-S) battery system, which has a high theoretical specific capacity and up to five-fold increase in energy density when compared to the best lithium-ion batteries, thus providing an intriguing candidate for next generation energy storage. However, there are critical challenges to overcome to realize viable Li-S battery systems, including protection of the Li anode from chemical reactions that cause the formation of an insulating solid-electrolyte interphase (SEI) layer, limiting both capacity retention and battery life.
New analytical tools have been developed for the study of advanced battery systems in destructive, post-mortem modes as well as while the battery is under operating conditions. Further, aspects of the battery chemistry and operation can also be modeled and reproduced with certain degrees of fidelity through computational studies that cross scales from the atomic and molecular to the sizes of pores and beyond. The combination of these experimental techniques and computational tools has begun the realization of predictive understanding of battery components and even their operation in the complete battery system, and we will report here on progress in merging operando studies utilizing advanced spectroscopies (NMR, EPR, x-ray, IR, etc.), in situ imaging (electron microscopy, XPS, etc.), and computational chemistry (especially ab initio and molecular dynamics simulations) to understand components of Li-S battery systems.
2:00 PM - ES04.08.02
Developing Plasmonic Imaging Technique to Understand Solid Electrolyte Interface Formation and Electrode Materials In Situ
Xiaonan Shan 1 , Chaojie Yang 1 , Ying-Chau Liu 1
1 Electrical and Computer Engineering, University of Houston, Houston, Texas, United States
Show AbstractDuring the operation of lithium-ion battery (LIB), a solid electrolyte interface (SEI) layer forms on the anode electrode materials due to side reactions with the electrolyte solvent and salt. It is essential to the performance of LIBs and it decides the initial capacity loss, self-discharge characterizstics, cycle life and safety. Therefore to understand the SEI formation is extremely important for battery research. Currently, most of characterization methods of SEI are based on electron microscope, although powerful, it is difficulty to directly map the SEI formation in-situ.
We have developed a novel plasmonic imaging technique to image the local SEI formation and measure the electrochemical reaction of the anode electrodes. Unlike conventional electrochemistry that measures the electrical current from entire electrode, the plasmonic-based electrochemical microscope (PECM) technique is based on sensitive imaging of surface plasmonic signal caused by electrochemical reaction, which is measured optically, thus allowing for fast and non-invasive imaging of electrode processes. PECM can image localized chemical reactions on the electrode surface ins-situ, this information will be extremely important for us to understand SEI formation and electrochemical reaction on the anode electrode. The electrochemical reaction will always be accompanied by a conversion of the chemical species between oxidized and reduced states, and plasmonic imaging is extremely sensitive to the species generated (or consumed) on electrode materials. Therefore, the PECM has great potential to characterize the local electrochemical reactions and energy storage process.
2:15 PM - ES04.08.03
In Situ X-Ray Reflectivity Study on the Atomic Scale Electrochemical Lithiation and Delithiation Process of Silicon
Chuntian Cao 1 2 , Hans-Georg Steinrueck 1 , Badri Shyam 1 , Michael Toney 1
1 SSRL Materials Science Division, SLAC National Accelerator Laboratory, Menlo Park, California, United States, 2 Materials Science and Engineering, Stanford University, Stanford, California, United States
Show AbstractSilicon is a promising anode material for lithium-ion batteries due to its excellent specific capacity (3579 mAh/g). However, the large capacity of Si is accompanied by a large volume expansion (~300%) which irreversibly destroys the Si crystallinity, resulting in loss of mechanical/electrical contact and capacity fading. In addition, capacity is lost due to the consumption of Li in the uncontrolled solid electrolyte interphase (SEI) growth. These issues render the main reasons limiting large scale commercialization of high capacity Si-based batteries.
Our study aims at a better understanding of the (de)lithiation mechanism of silicon (Si) electrodes and the concomitant SEI growth. Here, we used in situ synchrotron X-ray reflectivity (XRR) to investigate the first two (de)lithiation cycles of Si. Our model battery system consists of a native oxide terminated single crystalline Si (100) wafer as working electrode, Li metal as counter and reference electrode, and 1 M LiPF6 in 1:1 EC:DMC electrolyte.
Our results show that the lithiation of c-Si is a layer-by-layer, reaction limited two-phase process;[1] the delithiation of LixSi (resulting in amorphous Si) and the lithiation of a-Si are reaction-limited single-phase processes.[2] Furthermore, the thickness-density product of the inorganic SEI layer is observed to increase during lithiation and decrease during delithiation, resembling a “breathing” behavior, and the inorganic SEI layer thickness is determined to vary between 40 and 70 Å. Additionally, a low-electron-density “Li-dip” layer is found between SEI and LixSi during the delithiation process, suggesting kinetically limited ion transport within the SEI during discharge, which we speculate to be one of the origins of battery’s internal resistance.
Our findings provide a detailed mechanistic model of the first two lithiation processes, and sheds light on fundamental difference of Li ion reaction with crystalline and amorphous materials. The results on SEI also motivate further experimental and theoretical studies of the Li+ diffusion properties in the SEI.
References:
1. C. Cao, H. G. Steinrück, B. Shyam, K. H. Stone, M. F. Toney, In Situ Study of Silicon Electrode Lithiation with X-ray Reflectivity. Nano Lett, 2016. 16(12): p. 7394-7401.
2. C. Cao, H. G. Steinrück, B. Shyam, M. F. Toney, The Atomic Scale Electrochemical Lithiation and Delithiation Process of Silicon. Submitted to Advanced Materials
2:30 PM - ES04.08.04
Morphology of the Intermediate Phase between LiFePO4 and FePO4 Investigated by Scanning Transmission Electron Microscopy
Shunsuke Kobayashi 1 , Akihide Kuwabara 1 , Craig Fisher 1 , Yoshio Ukyo 2 , Yuichi Ikuhara 1 3
1 Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya Japan, 2 Office of Society-Academia Collaboration for Innovation, Kyoto University, Kyoto Japan, 3 Institute of Engineering Innovation, The University of Tokyo, Tokyo Japan
Show AbstractLiFePO4 is one of the most intensively studied cathode materials for lithium ion batteries. Improving its performance further requires a greater understanding of lithium intercalation and related processes, particularly in the vicinity of interfaces between lithiated and delithiated phases, viz., Li1-αFePO4 and FePO4, during charge/discharge. In this work, we examined the Li1-αFePO4/FePO4 interface when a single crystal is chemically delithiated from the (010) surface, which is perpendicular to the most rapid Li-ion migration direction. In order to determine the interface morphology, Li concentrations around the interface were mapped using state-of-the-art electron energy loss (EEL) spectroscopy techniques [1].
A commercially available LiFePO4 single crystal was used for all experiments. The crystal was mechanically cleaved perpendicular to each principal axis to prepare suitably thin specimens for microscopy analysis [2]. Chemical delithiation was performed in an acetonitrile solvent using NO2BF4 as the oxidant. The atomic-level structure of the delithiated Li1-αFePO4 crystal was investigated using an aberration-corrected scanning transmission electron microscope (STEM), and chemical compositions and charge states analyzed with an EEL spectrometer attached to a Wien filter monochromated aberration corrected STEM.
STEM observations showed that the as-cleaved surface was atomically flat, implying that it has low excess energy and high stability [2]. After partial chemical delithiation, a number of microcracks formed in response to the large difference in lattice volume between LiFePO4 and FePO4 phases. Li concentration maps revealed a well-defined intermediate phase of composition Li~0.67FePO4 between the two major phases. Boundary planes between FePO4 and the intermediate phase were mostly parallel to (100) and (210) planes, consistent with the lattice mismatch between LiFePO4 and FePO4 being largest in the [100] direction. Formation of the intermediate phase with this morphology thus plays an important role in ameliorating the large lattice strain (~4%) between LiFePO4 and FePO4 phases. The results illustrate how atomic-resolution microscopy analysis provides greater insights into the nature of the intermediate phase, phase transformation processes and relaxation mechanisms in LiFePO4 during delithiation.
[1] S. Kobayashi et al., Microscopy DOI: org/10.1093/jmicro/dfx012 (2017).
[2] S. Kobayashi et al., Nano Lett. 16 5409−5414 (2016).
[3] This work was performed as part of the Research and Development Initiative for Scientific Innovation of New Generation Batteries II (RISING II) project of the New Energy and Industrial Technology Development Organization (NEDO), Japan.
2:45 PM - ES04.08.05
Characterizing Segregation in Doped NMC Cathode Interfaces Using Machine Learning
Michael Chatzidakis 1 , David Rossouw 1 , Gianluigi Botton 1
1 , McMaster University, Hamilton, Ontario, Canada
Show AbstractOne common method of sample preparation of Li-ion battery cathode materials for transmission electron microscopy (TEM) is the use of Focused Ion Beam (FIB) milling to create electron transparent (30 – 100 nm thickness) window-like samples out of bulk materials. Such samples while thin enough to be electron transparent are thick enough to be problematic with respect to characterizing the phases at interfaces using electron energy-loss spectroscopy (EELS). Conventional characterization methods have great difficulty in identifying the chemical compounds in thin (<100 nm) battery coatings and segregated interfaces.
We present herein a spectroscopic signal unmixing approach to separate the EELS signals of interfacial compounds from the bulk materials for accurate interfacial phase identification. This can be achieved using unsupervised machine learning methods such as: principal components analysis (PCA) for denoising as well as independent component analysis (ICA) for signal unmixing. ICA is an extremely powerful statistical tool at discriminating between independent phases and this phase discrimination ability opens avenues for interfacial characterization that previously was not possible.
The EELS spectra of individual interfacial phases in a STEM-EELS spectrum image were successfully recovered at surfaces and grain boundaries in a doped polycrystalline NMC cathode material. They were recovered despite signal mixing between the interfacial phase and the bulk material by using the outlined statistical methods. Using the isolated interfacial EELS spectra, the stoichiometry of these phases could be roughly approximated by integrating the EELS edges.
The valency of Mn in the interfacial phase is typically challenging to determine due to the wide range of possible valence states and the influence of microscope parameters on the fine-structure of the EELS signals. However we developed a novel valence classification scheme using supervised machine learning to determine with high fidelity the valence of Mn. A database of known valences of various Mn compounds was collected in a variety of conditions, and a convolutional neural network classifier was used to find trends between each spectra and its respective valence. Using this trained classifier (accuracy exceeding 98 %), it was used to predict the valence of the unknown Mn compound at the interface of the NMC grain.
By adapting recent advances in machine learning into the fields of electron microscopy and materials science, we have improved our ability to characterize the interface of sensitive electrochemical materials. Using unsupervised learning methods such as ICA, stoichiometric data can be obtained and when combined with atomic valency derived from the fine-structure of the EELS spectra, enough information can be provided to successfully identify interfacial phases. The outlined method can be extended to characterize cycled materials and the many unique interfacial phases that are present.
ES04.09: Other Battery Materials II
Session Chairs
Tuesday PM, November 28, 2017
Hynes, Level 3, Ballroom A
3:30 PM - *ES04.09.01
Alkali Metal Ions Insertion Chemistry into Graphite Electrodes
Kisuk Kang 1
1 , Seoul National University, Seoul Korea (the Republic of)
Show AbstractThe insertion of guest species in graphite including alkali metal (AM) ions such as Li+, Na+, and K+ is the key feature utilized in applications ranging from energy storage and liquid purification to the synthesis of graphene. It was believed that the insertion of Na ions alone is thermodynamically impossible and co-intercalation of AM ions and solvent into graphite is considered undesirable because it can trigger the exfoliation of graphene layers and destroy the graphite crystal; however, it is recently demonstrated that solvated-AM ion intercalation can reversibly occur in graphite. This phenomenon enables graphite to function as a promising high-power capable anode for both Li/Na/K-ion batteries. First-principles calculations suggest that the chemical compatibility of the graphite host and [AM–solvent]+ complex ion strongly affects the reversibility of the co-intercalation, and comparative experiments confirm this phenomenon. In an effort to understand this behavior, we investigate the solvated-AM-ion intercalation mechanism using in operando X-ray diffraction analysis, electrochemical titration, real-time optical observation. The formation of various stagings with solvated-AM-ions in graphite is observed and precisely quantified for the first time. The ultrafast intercalation is demonstrated in real time using millimeter-sized highly ordered pyrolytic graphite, in which instantaneous insertion of solvated-AM-ions occurs (in less than 2 s). Moreover, it is revealed that [lithium–ether]+ co-intercalation of natural graphite electrode enables much higher power capability than normal lithium intercalation, without the risk of lithium metal plating, with retention of ≈87% of the theoretical capacity at current density of 1 A g−1. This unusual high rate capability of the co-intercalation is attributed to the (i) absence of the desolvation step, (ii) negligible formation of the solid–electrolyte interphase on graphite surface, and (iii) fast charge-transfer kinetics. The correlation between the properties of various solvents and the alkali metal ion co-intercalation further suggests a strategy to tune the electrochemical performance of graphite electrodes in rechargeable batteries. Furthermore, this work highlight the first step toward the utilization of fast and reversible [AM–solvent]+ complex ion intercalation chemistry in graphite for rechargeable battery technology.
4:00 PM - ES04.09.02
Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries
Yue Gao 2 , Yuming Zhao 1 , Yuguang Li 2 , Qingquan Huang 1 , Thomas Mallouk 2 , Donghai Wang 1
2 Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, United States, 1 Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractLithium (Li) metal anode suffers severe interfacial instability from the high reactivity towards liquid electrolytes especially carbonate-based electrolytes, resulting in poor electrochemical performances of Li-metal batteries using 4-V high-capacity cathodes. Herein, we developed a skin-grafting strategy to stabilize the Li metal-liquid electrolyte interface by coating a chemically and electrochemically active polymer layer onto the Li metal surface. This layer serves as a grafted skin of Li metal anode to not only graft additional components into solid-electrolyte interphase (SEI) but also accommodate the Li deposition/dissolution underneath the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing Li metal anode with grafted skin paired with LiNi0.5Co0.2Mn0.3O2 cathode presents a long cycle life of a 90.0 % capacity retention after 400 cycles with a capacity of 1.2 mAh/cm2 in the carbonate-based electrolyte. This proof-of-concept study provides a novel direction to regulate the interfacial chemistry of Li metal anode and enable high-performance Li-metal batteries.
4:15 PM - ES04.09.03
MgMn2O4 Spinel Oxides as Cathode for Mg-Ion Battery
Quang Duc Truong 1 , Itaru Honma 1
1 , Tohoku University, Sendai Japan
Show Abstract
The rechargeable magnesium battery have attracted attention owing to the high natural abundance of Mg, safety, high specific capacity (2205 Ah kg−1), and especially high volumetric energy density (3833 mA h cm−3).1,2 The MgMn2O4 spinel oxide are of significant importance for Mg-ion battery owing to its superior specific capacity (272 mA h g−1) and high energy density (1000 Wh kg−1). We report the investigation of surface structure of magnesium manganese spinel oxide MgMn2O4 using spherical aberration-corrected scanning transmission electron microscopy (STEM) and show the existence of a thin stable rocksalt MgMnO2 phase with retention of bulk MgMn2O4 spinel phase. Furthermore, the spinel MgMn2O4 exhibited a wide voltage plateau at around 2.8 V versus Mg/Mg2+ in coin-cell type with an initial discharge capacity of 97 mA h g–1 at current rate of 0.0139 C.
MgMn2O4 materials were prepared by amorphous metal complex method. The electrochemical performance of MgMn2O4 was investigated using coin-type cells (CR2032). The working electrodes is composed of 80 wt.% MgMn2O4, 10 wt.% PTFE (poly(tetrafluoroethylene)) as a binder and 10 wt.% acetylene black. The capacitive anode was prepared by mixing of 80 wt.% Maxsorb MSC-30, 10 wt.% PTFE (poly(tetrafluoroethylene)) as a binder and 10 wt.% acetylene black. The electrolyte consists the solution of 0.5 M Mg(ClO4)2 in acetonitrile.
HAADF-STEM imaging indicates that the bulk of the crystal show diamond configuration of spinel framework, however, the surface exhibits clearly diamond configuration with visible contrast at center octahedral sites and the absence of contrast at the tetraheral sites. By matching the ADF image with the schematic illustration of atomic arrays in inset; it clearly reveals the presence of rocksalt structure on the surface.
The cyclic voltammograms of the cell containing MgMn2O4 electrode show broaden oxidation peak at 3.3 V and one reduction peak centered at 2.8 V versus Mg/Mg2+. The CV curves were identically reproduced at subsequent cycles, suggesting the good cyclic performance of the cell. The spinel MgMn2O4 exhibited a wide voltage plateau at around 2.8 V versus Mg/Mg2+ with an initial discharge capacity of 97 mA h g–1 at current rate of 0.0139 C. Interestingly, the specific capacity increased continuously cycle by cycle and reached 169 mA h g–1 after 27 cycles. At the 8th and 17th cycles, the discharge capacities are determined to be 135 and 154 mA h g–1, corresponding to the insertion of 0.5 and 0.57 Mg atoms per formula unit, respectively.
1. 1. Q. D. Truong, M. K. Devaraju, P. Tran, Y. Gambe, Y. Sasaki, I. Honma, Chem. Mater. 2017, under revision.
2. Q. D. Truong, M. K. Devaraju, Y. Gambe, Y. Sasaki, P. Tran, I. Honma, et. al. Nano Lett. 2016, 16, 5829−5835.
4:30 PM - ES04.09.04
Energy Storing MXene Hybrid Fibres with High Volumetric Capacitance
Shayan Seyedin 1 , Jozelito Razal 1
1 Institute for Frontier Materials, Deakin University, Geelong, Victoria, Australia
Show AbstractThe emergence of graphene sparked the synthesis of a diverse range of two-dimensional (2-D) nanomaterials that demonstrated a selection of remarkable electrical, mechanical, optical, and thermal properties. MXenes, a recently discovered family of 2-D early transition metal carbides or carbonitrides, have presented a distinct combination of metallic conductivity, outstanding electrochemical properties, and hydrophilic behaviour. The utilisation of their excellent properties for real-life applications requires their integration into macroscopic structures such as films, papers, and fibres. Previous research in this area, showed that MXenes could be used to prepare films, papers, and composites for applications in energy storage devices, electromagnetic shielding, water purification, and heavy metals absorption. However, because of small sheet size (<2 µm), low processability, weak inter-sheet interactions, and lack of efficient processing, the fabrication of MXene-based fibres has not been possible to date. In this work, for the first time we achieve fibres from the most prominent member of MXene family (Ti3C2). We produce the MXene-based fibres using a wet-spinning technique by taking advantage of the templating role of liquid crystalline (LC) graphene oxide (GO). The favourable interactions of GO and MXene flakes result in the preservation of the LC property of the GO dispersion at an extremely high MXene content of ~87.8 wt. %, a key to its fibre processing. The MXene-based fibre demonstrate excellent flexibility by forming a knot without showing signs of microstructural damage. A high volumetric capacitance of ~341 F cm-3 is achieved for the MXene hybrid fibre. The MXene hybrid fibres developed in this work, introduce a new class of fibres from an emerging family of 2-D nanomaterials, and are excellent candidates for a variety of applications such as wearable energy storage.
4:45 PM - ES04.09.05
Investigating the Zinc/Electrolyte Interface of the Minimal Architecture Zinc-Bromine Battery
Kevin Knehr 1 , Shaurjo Biswas 1 , Daniel Steingart 1
1 , Princeton University, Princeton, New Jersey, United States
Show AbstractFor electrochemical energy storage on the grid scale, the major design criteria are low cost and long lifetime. One technology that has shown the potential to meet these requirements is the zinc-bromine redox flow battery, which has been shown to perform with less than 20% capacity fade for 10,000 cycles [1]. Despite this impressive lifetime, the cost of this technology (>$200 kWh) is still prohibitive even though the active materials and carbon electrodes, where the reactions occur, only account for ~$8 kWh. The majority of the cost comes from the system level, where complexing agents, separation membranes, and flow systems are used to prevent the corrosive bromine from reacting with the zinc electrode.
In light of this fact, our lab has developed a minimal architecture zinc-bromine battery (MA-ZBB), which utilizes the same chemistry from commercial zinc-bromine flow batteries, but eliminates the need for any passive components, significantly reducing the cost (projection of ~$94/kWh cell cost) [2]. The MA-ZBB is composed of two carbon based electrodes in a zinc-bromide electrolyte, which are spatially separated in the vertical direction. During charging, zinc is plated on a carbon cloth at the top of the cell and bromine is generated within a carbon foam located on the bottom. During discharge, these processes are reversed: zinc and bromine are converted back into their ionic states, which dissociate within the electrolyte. To limit the bromine/zinc interaction, the electrodes in the MA-ZBB are vertically separated to utilize the variations in density between bromine and the aqueous electrolyte as an advantage to minimize self-discharge.
To date, we have demonstrated an energy efficiency of over 60% for over 1000 cycles at a moderate capacity on the lab scale. Improving the efficiency and increasing the cell capacity requires an understanding of the processes occurring at the zinc electrode. This work presents on resent efforts at analyzing the phenomena occurring at the zinc/electrolyte interface using electrochemical and materials characterization techniques. In particular, we seek to quantify the relative importance of hydrogen generation and bromine/zinc self-discharge on the coulombic efficiency and capacity of the MA-ZBB.
[1] R. M. Darling, K. G. Gallagher, J. A. Kowalski, S. Ha, and F. R. Brushett, Energy Environ. Sci., 7 (2014) 3459.
[2] Shaurjo Biswas, Aoi Senju, Robert Mohr, Thomas Hodson, Nivetha Karthikeyan, Kevin. W. Knehr, Andrew G. Hsieh, Xiaofang Yang, Bruce E. Koel, Daniel A. Steingart, Energy Environ. Sci., 10 (2017) 114.
ES04.10: Poster Session II
Session Chairs
Wednesday AM, November 29, 2017
Hynes, Level 1, Hall B
8:00 PM - ES04.10.01
Electrochemical Battery Testing Methods Designed for Safety and Efficiency in a Research Laboratory
Michael Kubicsko 1 , Corrado Locati 2
1 , Metrohm USA, Riverview, Florida, United States, 2 , Metrohm Autolab, Utrecht Netherlands
Show AbstractElectrochemical battery testing is performed under either potentiostatic or galvanostatic control and often results in the need to manage potentials on the order of tens of volts and currents higher than one ampere. Strategies to carry out popular electrochemical battery testing experiments safely and efficiently with an instrument intended for general laboratory purposes, such as the Metrohm Autolab PGSTAT302N, by using a few additional accessories and the NOVA 2 electrochemical software package. While single-cell batteries may have a nominally low voltage, these batteries are often available in packs with multiple cells in series. When characterizing a pack of batteries, the total voltage can reach values greater than 10 volts. However, the measureable potential range for the PGSTAT302N is ±10 V. This contribution demonstrates how the potential range may be extended to ±30 volt using a voltage divider/multiplier, so that the instrument can be used for potentiostatic charge and discharge measurements on higher voltage packs. Furthermore, potentiostatic and galvanostatic intermittent titration techniques (PITT and GITT) are demonstrated as a technique to determine diffusion coefficients of lithium ions in a solid state electrode material. PITT and GITT were applied to the characterization of a Li-ion battery with a nominal voltage of 3.75 volts. In this example, the current booster and voltage multiplier are not necessary.
Since battery testing applications may take a general purpose PGSTAT to the upper limit of its intended specifications, the safety of the researcher and the instrument must be considered in the experiment design. The potential and current limitations of the instrument are related to its power management capabilities. Exceeding the specifications can lead to permanent damage of the equipment or subtle drifts in the measurement that result in unreliable data depending on the magnitude of the overload. In addition, working outside of the battery’s own specifications could lead to heating, expansion, and possible explosion of the specimen, creating an unacceptable risk for the researcher. To this end, it is recommended to implement cutoffs on the maximum current, potential, or power associated with the electrochemical measurement. In this contribution, the use of cutoffs for safety and convenience is highlighted for the above-mentioned examples (charge/discharge, PITT, and GITT).
8:00 PM - ES04.10.02
Spray Deposited Polymer-rGO Electrodes for High Voltage Solid-State Supercapacitors
Neetesh Kumar 1 , Riski Titian Ginting 1 , Jae-Wook Kang 1
1 , Chonbuk National University, Jeonju Korea (the Republic of)
Show AbstractIn recent years, a great attention has been paid to develop wearable energy storage devices like high performance flexible solid state supercapacitors (SSCs) or batteries.The textile-based (polyester, cotton) SSCs suffer from poor performance due to high resistance of electrode material, so, new materials with conductivity and flexibility have been developed to improve performance but still there is big gap between promising laboratory results that usually require nano-structured materials and fine-scale processing approaches and current manufacturing technology that operates at large scale. In this work, we demonstrate, a new, low-cost, energy efficient, scalable spray technique and a chemical treatment method to fabricate high-performance SSCs on flexible carbon cloth utilizing PEDOT: PSS conducting polymer and PEDOT: PSS/rGO composite as an active material. The electrodes treated with chemicals showing improved electrical conductivity, low interfacial resistance, and ion diffusion. The SC devices fabricated from chemically treated PEDOT: PSS-rGO electrodes and PVA-H3PO4 gel electrolyte, operates at high voltage (voltage window of 0~2.0V), yielding high area and specific capacitance of ~2900 mFcm-2 and ~120 Fg-1, respectively, at a scan rate of 10 mV/s. The large area (23.5 cm2) PEDOT: PSS-based SSCs showing capacitance of ~5.2 F with a specific capacitance of ~60 Fg-1 at a loading of 4.0 mgcm-2. Our spray manufacturing approach provides a new way to fabricate high power, large area, wearable energy storage devices.
8:00 PM - ES04.10.03
Shungite as a Natural Resource for Battery Electrodes
Neal Pierce 1 , Nam Chou 1 , Yu Lei 2 , Nestor Perea Lopez 2 , Kazunori Fujisawa 2 , Joshua Robinson 3 , Gugang Chen 1 , Sergey Rozhkov 4 , Natalia Rozhkova 4 , Mauricio Terrones 2 3 , Avetik Harutyunyan 1
1 , Honda Research Institute USA Incorporated, Columbus, Ohio, United States, 2 Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania, United States, 3 Department of Materials Science and Engineering and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania, United States, 4 Institute of Geology, Karelian Scientific Center RAS, Petrozavodsk Russian Federation
Show AbstractVariety of structures of synthetic carbon allotropes embrace tremendous potential for energy storage, particularly for secondary batteries. There have been number of reports on synthesis of carbonaceous anode materials with lithium (Li) storage capacity larger than the theoretical limit for graphite (372 mAh/g, corresponding to LiC6). However, besides the performance, available resources and cost efficiency are apparent obstacles that could hinder their wide exploitation. Here we present black Precambrian rock “shungite” as a natural resource for a Li ion battery anode. It was found that upon structural modifications the energy density of shungite can exceed the density of another natural resource: graphite and become comparable to synthetic material: non-graphitisable (“hard”) carbon (~400 mAh/g). High-resolution transmission electron microscopy studies of modified shungite suggest that it consists of spatially arranged fractals of bent, curved, mono- or stacked graphene layers as well as closed shells. The features of ex-situ 7Li nuclear magnetic resonance spectra of lithiated “shungite” show distinct differences from that of graphite. We believe that the origin of enhanced storage capacity is analogue to hard carbon, yet the presence of open edge stacked graphene flakes and curved topography could play an essential role by increasing accessibility and tuning the adsorption energy of occluded Li atoms. We suggest “shungite” as an alternative natural resource for fabricating efficient electrodes in the fast growing battery industry.
8:00 PM - ES04.10.04
Ionic Conductivity in Liquid Electrolyte Solutions as a Material Science Problem
Chae-Ho Yim 1 , Yaser Abu-Lebdeh 1 , Xiuyun Zhao 1
1 , National Research Council of Canada, Ottawa, Ontario, Canada
Show AbstractThere is no one accepted model or theory to explain the conductivity of concentrated electrolyte solutions. However, very recently we applied the original ideas of Doolittle and Cohen-Turnbull on free volume to molecular liquid electrolytes and a new relationship that correlate transport to free volume was introduced [1]. Also, we proposed a model to explain transport and structure in concentrated solutions where stable ion-solvent species, ionic clusters and ionic networks might form and show a maximum in conductivity at the eutectic composition of the salt-solvent phase diagram and also a switch in conductivity mechanism from vehicular to Grotthuss-type mechanism. Herein, we extend the work by taking into account changes to thermal energy, coulombic energy and free volume within the electrolyte solution over the whole range as a result of different interactions among ionic charges, solvent dipoles and the free space in between. Dodo et al [2] treated highly concentrated solutions as a high-density, strongly-coupled plasma and expressed normalized, non-dimensional conductivity as a function of a single parameter, a coupling constant that is a ratio of thermal energy to coulombic energy. We combined our work on free volume and the plasma model to treat the liquid electrolyte as a solid material that is made of a “liquid” unit cell composed of random arrangement of cations and anions and solvent molecules and here we introduce a newly modified equation.
[1] C.-H. Yim, J. Tam, H. Soboleski, Y. Abu-Lebdeh, J. Electrochem. Soc.,164(6), (2017), A1002-A1011.
[2] T. Dodo, T.-A. Nakagawa and E. Nonaka, Japanese Journal of Applied Physics, 32, (1993), 1236-1241.
8:00 PM - ES04.10.05
Coaxial Fiber-Shaped Asymmetric Supercapacitor Based on Nanostructured MnO2/CNT-Web Paper and Fe2O3/Carbon Fiber Electrodes
Bebi Patil 1 , Sungdong Cho 1 , Heejoon Ahn 1
1 , Hanyang University, Seoul Korea (the Republic of)
Show AbstractThe coaxial fiber-shaped asymmetric supercapacitor (CFASC) is a promising energy storage device in wearable and portable electronics, because of its high flexibility, small size, and light weight. However, the energy density of most of the fiber shaped supercapacitors is limited due to their limited potential range. Herein, we successfully developed a CFASC made up from MnO2/CNT-web paper as a cathode coupled with Fe2O3/carbon fiber as an anode with high operating voltage (2.2 V). The prepared CFASC device shows a high volumetric energy density of 0.449 mWh cm-3 at a power density of 0.022 W cm-3, which is appreciably higher than most reported fiber type supercapacitors. Additionally, CFASC exhibits good rate capability, long cycle life, and high volumetric capacitance (0.67 F cm-3) with excellent flexibility. The promising performance of CFASC illustrates its potential for portable and wearable energy storage.
8:00 PM - ES04.10.06
Interface Stability in the La-Sr-Ca-Mg-Ni-O System for Metal-Air Batteries
Nuri Solak 1
1 Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul Turkey
Show AbstractThe ternary nickelates with a layered perovskite structure are known as highly active for the oxygen reduction reaction (OOR) and the oxygen evolution (OER) in metal-air batteries. Doped lanthanum nickelates have also been considered as a potential cathode material for intermediate temperature solid oxide fuel cell applications. In our previous studies, it is computationally determined that the performance of nickelate type cathode can be improved by SrO doping. However, there is no detailed literature information on phase equilibria studies in the La2O3-SrO-NiO based high order oxide systems. In order to build chemically stable battery and fuel cells, not only the thermodynamic stability of the electrolyte and electrodes themselves, but also the reactivity between component materials should be well established. The work aimed to investigate ternary phase equilibria in the La2O3-SrO-CaO-MgO-NiO high order oxide system in order to investigate thermodynamic stability of the doped nickelates. The experimental work has been designed based on the calculated phase diagrams (CALPHAD calculations). In the La-Sr-Ca-Mg-Ni-O system, extended solid solutions of (La,Sr)2NiO4 , (La,Ca)2NiO4 and La2(Ni,Mg)O4 were found and the homogeneity range was experimentally determined. Also chemical potential diagrams of the system simulating fabricating and operation conditions were calculated.
8:00 PM - ES04.10.07
Electrochemical Studies of Poly(vinylidene difluoride-co-hexafluoropropylene) Nanofiber Separator for Sodium Battery
S. Janakiraman 1 , Rasmita Biswal 1 , Sudipto Ghosh 1
1 , IIT Kharagpur, Kharagpur India
Show AbstractIn this study, nanofibrous mats were developed from Poly(vinylidene difluoride-co-hexafluoropropylene) [P(VdF-co-HFP)] using electrospinning technique. The process parameters are optimized to 16 wt% polymer solution and 18 kV electric field to get a bead free structure. The electrospun mats had an interconnected open pore network structure with a high porosity. A polymer electrolyte was prepared by soaking the celgard (2500) membrane and electrospun mat in 1M NaClO4 in EC: DEC (1:1, v/v) for 4 hours. The physicochemical characteristics of the mats are investigated by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and sodium ion conductivity. The ionic conductivity was found to be 0.15 x 10-3 S cm-1 and 1. 23 x 10-3 S cm-1 for celgard (2500) and electrospun mat at room temperature. The galvanostatic charge-discharge was performed for the sodium ion cell with Na0.66Fe0.5Mn0.5O2 as a cathode, sodium metal as an anode and soaked electrospun mat as an electrolyte in the voltage range of 1.5 V – 3.8 V. The discharge capacity was 163 mAhg-1 for an electrospun mat at C/10 rate. The sodium ion half-cell gave a stable performance up to 50 cycles with a little loss in the capacity.
8:00 PM - ES04.10.08
Development of a Novel Decoupled Lithium-Ion Hybrid Solid Electrolyte with Fast and High Ionic Conductivity for Electrochemical Devices Application
Victoria Castagna Ferrari 1 , Flavio De Souza 1
1 , UFABC, Santo Andre Brazil
Show AbstractThis work presents a novel solid electrolyte which consists of a segmental motion-decoupled hybrid polymer chain with desirable ionic conductivity for a solid state. It was synthesized by a simple chemical route of a polymer chain containing germanium as a central atom using the polymeric precursor method. The main purpose of preparing a hybrid polymer is to enable a higher ion mobility with a rigid polymer chain due to the electronegativity of germanium. Different samples were synthesized to characterize their structure by changes in ion (Li+ and Na+) and on their concentrations. Structural analysis including FTIR (Fourier Transform Infrared), FT-Raman (Fourier Transform Raman Spectroscopy) and XRD (X-Ray Diffraction) techniques were performed to localize the preferred ion sites on the polymer chain, to understand its planar structure and to verify that the electrolyte is amorphous at room temperature. In addition, thermal analysis by the DSC (Differential Scanning Calorimetry) technique confirmed only one glass transition temperature with no peaks in the curve and spectroscopy impedance measurements were performed to verify the ionic conductivity behaviour of the developed solid electrolyte at different temperatures. The electrolyte with 10% w.t. of Li+ was combined with a 1 layer deposition of tungsten oxide electrode (electrochromic material) and, after the application of a -1.5V potential, the change in transmittance from bleached state (transparent) to a coloured state (blue) of the electrode was 40% at 550 nm in a fast time (20 seconds). The developed solid hybrid electrolyte thus has demonstrated its powerful application in intercalation process in electrochemical devices mainly by its “hopping” charge transfer mechanism.
Acknowledgements
We gratefully acknowledge financial support from the Brazilian agencies of CAPES, CNPq and FAPESP (grant 2013/07296-2).
8:00 PM - ES04.10.09
The Effect of Composite Protection Layer on the Surface-Patterned Li Metal Anodes
Jinkyu Park 1 , Seok Woo Kim 1 , Dahee Jin 1 , Hyunkyu Jeon 1 , Yong Min Lee 2 , Myung-Hyun Ryou 1
1 Chemical and Biological Engineering, Hanbat National University, Daejeon, SE, Korea (the Republic of), 2 Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu Korea (the Republic of)
Show AbstractDue to the necessity of using high-energy density battery systems for electric vehicles (EVs) and energy storage systems (ESSs), much attention has been focused on the development of post lithium-ion batteries (LIBs) such as Li-Air and Li-S battery systems. Contrary to conventional commercialized LIBs using carbonaceous anodes (i.e., graphite), they use lithium metal as anodes. Despite a long history of research over four decades, lithium metal anodes cause not only a safety problem of batteries but also poor cycle performance because of uncontrolled dendrite formation during repeated cycles.
Recently, to solve this bottleneck, we developed a surface-patterned lithium metal anodes by applying sophistically designed micro-sized patterned on the bare lithium metal by a stamping technique. The surface-patterned lithium metal showed significantly improved cycle performance and rate capability compared to bare lithium metal. Nevertheless, the bulky dendrite was formed in the patterned grooves at a fast lithium plating rate. The dendrite would consume large number of electrolytes during repeated cycles, resulting in poor cell performance.
To improve the cycle performance of lithium metal by inhibiting the dendrite formation in the patterned grooves, we introduced the inorganic composite protection layers on the surface-patterned lithium metal and investigated the synergistic effect between them. The basic electrochemical evaluation such as cycle performance and rate capability was conducted and the surface morphology changes were evaluated using SEM and microscope.
8:00 PM - ES04.10.10
Effect of Co-Polyimide(PI) P84 as a Binder for Stabilized Lithium Metal Powder(SLMP) Electrode
Dahee Jin 1 , Jeonghun Oh 1 , Danoh Song 1 , Seok Woo Kim 1 , Hyunkyu Jeon 1 , Jinkyu Park 1 , Yong Min Lee 2 , Myung-Hyun Ryou 1
1 , Hanbat University, Dajeon, SE, Korea (the Republic of), 2 , DGIST, Daegu Korea (the Republic of)
Show AbstractBecause of the highest theoretical capacity (3860 mAh g-1 or 2060 mAh cm-3) and lowest negative electrochemical potential (-3.04 V vs standard hydrogen electrode), lithium (Li) metal has been considered as a promising anode candidate for a large scale battery system such as electric vehicles (EVs) and energy storage systems (ESS). However, the uncontrolled dendrite growth during repeated cycles, which is the origin of safety issue and poor cycle performance, has been hindered the successful implementation of Li metal anodes.
Small current density and uniform current distribution over Li metal are key to controlling dendrite formation. Since the SLMP has about 4.5 times larger surface area than Li foil electrode, the use of stabilized Lithium metal powder (SLMP) has been proposed.
From many previous electrode studies of LIBs, we have discerned that the polymeric binders play an important role in electrochemical performance. Similar to LIB electrodes, the SLMP-based Li metal electrodes are fabricated by casting a coating slurry consisting of SLMP, polymeric binders, and organic solvent onto Cu foil. Consequently, the polymeric binders affecting the adhesion properties between SLMP particles as well as between Cu foil and SLMP should be carefully selected and studied.
Recently, we have verified that P84 is promising for Si anodes and inorganic composite coating layers of ceramic composite separators. In contrast to commercial polyvinylidene fluoride (PVdF) binders, which easily lose adhesion due to electrolyte swelling, P84 maintains excellent adhesive/cohesive within the electrode composite as well as between the electrode composite and current collectors.
Here in, we investigated the effect of P84 as a polymeric binder in SLMP electrodes for Li metal secondary batteries. The properties of P84 was studied by using galvanostatic cycling test, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and surface and interfacial cutting and analysis system (SAICAS).
References
[1] Heine, Jennifer, et al. Advanced Energy Materials 4.5 (2014).
[2] Heine, Jennifer, et al. Electrochimica Acta 138 (2014): 288-293.
[3] Seong, Il Won, et al. Journal of Power Sources 178.2 (2008): 769-773.
8:00 PM - ES04.10.11
Effect of Boron Oxide Surface Modification on the Cycling Stability of High Ni System Cathode Materials
Kwang-Hwan Cho 1 , Dohyung Park 2 , Il-seok Kim 1
1 , Samsung SDI R&D Center, Suwon-Si Korea (the Republic of), 2 , AEB) Cell Development Group, Youngin Si Korea (the Republic of)
Show AbstractNickel-rich layered metal oxide materials are prospective cathode materials for lithium ion batteries due to the relatively higher capacity and lower cost than LiCoO2. Nevertheless, the layered Ni-rich oxide cathode suffers from a tremendous structural degradation during long-term cycling, causing the drastic rise of electrode impedance and deterioration of the capacity retention. In this work, we developed a novel method to stabilize its surface structure by boron oxide. The presence of boron oxide is identified via X-ray photoelectron spectroscopy and transmission electron microscopy analysis. In the resulting sample, the boron oxide on the surface of Ni-rich oxide are 10-15 nm thick. Scanning electron microscopy with FIB and were used to study pristine and surface modified samples subjected to accelerated calendar-life testing at temperatures ranging from 25 to 60°C. Studies indicate that the presence of 1–2 wt% boron oxide results in an improved capacity and better capacity retention with cycling. Impedance measurement reveals a reduced charge-transfer resistance for the boron oxide modified samples suggesting that the presence of boron oxide can successfully suppress the deterioration of the electrode/electrolyte interface, thus contributing to the overall cycling stability enhancement. Surface modification with boron oxide is a feasible approach for improving the comprehensive properties of cathode materials.
8:00 PM - ES04.10.13
Hybridization of Carbon Nanotubes with Activated Carbon and MnO2 for Electrochemical Capacitor Electrodes
Soki Kuzuhara 1 , Misato Narubayashi 1 , Suguru Noda 1 2
1 Department of Applied Chemistry, Waseda University, Tokyo Japan, 2 Research Institute of Science and Engineering, Waseda University, Tokyo Japan
Show AbstractElectrochemical capacitors have attracted increasing attention as high power electrochemical energy storage devices. Owing to the growing demands for normalizing power fluctuations of solar and wind power generation and energy recovery in automobiles, improvement of energy density is extensively researched.
In this work, we focused on MnO
2. MnO
2, with high theoretical specific capacitance (1370 F/g), is a promising candidate as an active material for commercial use because it is abundant, inexpensive, and environmentally friendly. However, the electric conductivity of MnO
2 is low and the redox reaction occurs preferentially on or near the surface during charge and discharge [1]. To overcome this issue, we deposit fine MnO
2 particles on self-supporting composite[s1] papers of activated carbon (AC) and carbon nanotubes (CNTs). CNTs have unique one-dimensional nanostructure, and simple dispersion-filtration transforms CNT powders to self-supporting, flexible papers of networked CNTs with good electrical conductivity. AC/CNT papers will hold many MnO
2 particles owing to their high specific surface area and large pore volume.
Submillimeter-long few-wall CNTs produced by fluidized-bed chemical vapor deposition method (1.5 mg) [2] and AC (YP-80F from Kuraray Chemical) (3.5 mg) were dispersed in 30 mL ethanol. Then, it was vacuum filtrated, and 30 μm thick AC/CNT hybrid paper was fabricated. MnO
2 was electrodeposited on the AC/CNT paper using 0.6 M MnSO
4/0.8 M H
2SO
4 aq. at constant current. MnO
2/AC/CNT hybrid papers were fabricated with controllable MnO
2 contents of 50−90 wt%. The electrochemical analysis was conducted with cyclic voltammetry in a three-electrode cell, which consisted of a MnO
2/AC/CNT working electrode, an AC/CNT paper (90 wt% AC with 10 wt% CNTs, ~200 μm in thickness) [3] as the counter electrode and an Ag/AgCl reference electrode (in saturated aqueous NaCl) with a 1 M Na
2SO
4 aq. electrolyte. The 38 μm-thick[s2] MnO
2/AC/CNT hybrid paper showed fairly high rate performance of 90 F/g
electrode[s3] , 57 F/cm
3, and 0.22 F/cm
2[s4] at 100 mV/s. Then, galvanostatic charge discharge was conducted with a two-electrode cell. The two-electrode cell consisted of the MnO
2/AC/CNT working electrode, an AC/CNT counter electrode with a 1 M Na
2SO
4 aq. electrolyte. The MnO
2/AC/CNT hybrid paper showed 6.6 kW/kg
electrode[s5] and 5.0 Wh/kg
electrode[s6] at 10 A/g at 0.8 V operation voltage.[s7] Different electrolytes will be studied to operate at higher voltages and enhance the power and energy densities.
References:
[1] M. Toupin, et al., Chemistry of Materials 16(16), 3184 (2004)
[2] Z. Chen, et al., Carbon 80, 339 (2014).
[3] R. Quintero, et al.
RSC Advances 4.16, 8230 (2014).
*Corresponding Author: S. Noda
Tel&Fax: +81352862769
Email:
[email protected]Web:http:www.f.waseda.jp/noda/
8:00 PM - ES04.10.14
Li+ Intercalation and Deintercalation Reactions with Graphene Films on LiPON
Keita Miyoshi 1 , Takayuki Yamamoto 1 , Munekazu Motoyama 1 , Yasutoshi Iriyama 1
1 Engineering, Nagoya University, Nagoya Japan
Show AbstractThe graphite anode has most commonly been used in lithium ion battery (LIB). Graphite is constituted by stacked graphene layers that are two-dimensional (2-D) sheets composed of carbon atoms in honeycomb lattice. Li ions are intercalated into graphite during the charging of LIB. The intercalation process of Li ions into graphite follows a staging mechanism, in which Li ions are inserted into a 2-D space between two adjacent graphene layers while keeping a spatial periodicity in the c axis of the graphite. The number of empty layers of graphene between each Li-occupied layer is defined as the stage number. In the dilute stage 1, Li ions randomly occupy available sites. Subsequently, they diffuse to fill different sites while keeping three interlayers empty in series (stage-4). The stage number gradually decreases to three (stage-3), two (stage-2), and one (stage-1) with the progress of the Li+ intercalation reactions [1].
Most of previous studies on the staging mechanisms of the Li intercalation reactions into the graphite anode have used organic liquid electrolytes. Solvents (e.g. propylene carbonate) of these electrolytes are electrochemically unstable at potentials where the Li intercalation reactions into graphite occur. The reductive decomposition of the organic solvents accompanies the formation of the solid electrolyte interphase (SEI) on the graphite surface and even inside graphene layers [2]. Li ions are supposed to conduct through the SEI to react with graphite. Hence, the presence of the SEI hinders the detailed analyses on the Li intercalation reactions with graphite. For example, it has been unclear why any potential plateaus do not appear in two-phase-coexistence regions between stage-4 and stage-3 and between stage-3 and stage-2L.
In this study, we investigate the Li+ intercalation and deintercalation reactions with thin graphene films coated with lithium phosphorous oxynitride glass (LiPON) electrolyte because LiPON does not form polymerized SEI on the graphite anode. The dependence of the charge transfer resistance for the graphene/LiPON interface in each stage is examined by the measurements of cyclic voltammometry (CV) and electrochemical impedance spectroscopy.
[1] J. Hui et al., ACS Nano, 10, 4248 (2016).
[2] J. O. Besenhard et al., J. Power Sources, 54, 228 (1995).
8:00 PM - ES04.10.15
Double-Layer Graphene Outperforming Monolayer as Catalyst on Silicon Photocathode for Hydrogen Production
Joonhee Moon 1 , Uk Sim 2 , Cheolho Jeon 1 , Ki Tae Nam 2 , Byung Hee Hong 2
1 , Korea Basic Science Institute, Daejeon Korea (the Republic of), 2 , Seoul National University , Seoul Korea (the Republic of)
Show AbstractPhotoelectrochemical cells are used to split hydrogen and oxygen from water molecules to generate chemical fuels to satisfy our ever-increasing energy demands. However, it is a major challenge to design efficient catalysts to use in the photoelectochemical process. Recently, research has focused on carbon-based catalysts, as they are nonprecious and environmentally benign. Interesting advances have also been made in controlling nanostructure interfaces and in introducing new materials as catalysts in the photoelectrochemical cell. However, these catalysts have as yet unresolved issues involving kinetics and light-transmittance. In this work, we introduce high-transmittance graphene onto a planar p-Si photocathode to produce a hydrogen evolution reaction to dramatically enhance photon-to-current efficiency. Interestingly, double-layer graphene/Si exhibits noticeably improved photon-to-current efficiency and modifies the band structure of the graphene/Si photocathode. On the basis of in-depth electrochemical and electrical analyses, the band structure of graphene/Si was shown to result in a much lower work function than Si, accelerating the electron-to-hydrogen production potential. Specifically, plasma-treated double-layer graphene exhibited the best performance and the lowest work function. We electrochemically analyzed the mechanism at work in the graphene-assisted photoelectrode. Atomistic calculations based on the density functional theory were also carried out to more fully understand our experimental observations. We believe that investigation of the underlying mechanism in this highperformance electrode is an important contribution to efforts to develop high-efficiency metal-free carbon-based catalysts for photoelectrochemical cell hydrogen production.
8:00 PM - ES04.10.16
Oligoanilines as a Suppressor of Polysulfide Shuttling in Lithium-Sulfur Batteries
Chi-Hao Chang 1 , Sheng-Heng Chung 1 , Arumugam Manthiram 1
1 , University of Texas at Austin, Austin, Texas, United States
Show AbstractLithium-sulfur (Li-S) batteries are considered as one of the most potential candidates for next-generation energy storage systems. This is mainly because of the high theoretical capacity of sulfur (1675 mA h g-1). Moreover, sulfur is ubiquitous, cost-effective, and environmentally benign. However, the practical application of Li-S batteries could not be realized because the intrinsic insulating nature of sulfur and its end product Li2S leads to low electrochemical utilization. More importantly, the migration of small polysulfide (LiPS) chains through the porous polymeric separator seriously jeopardizes the cycle life and energy density of Li-S batteries. Herein, we employ an organic oligoaniline, an amine-capped aniline trimer (ACAT) to enlarge the migrating species, which are then size-selectively sieved by the separator, thereby suppressing the LiPS migration in Li-S cells. The strong interaction between LiPS and ACAT facilitates the formation of bulky ACAT-LiPS complexes (organoLiPS complexes), which are then size-selectively sieved by the porous polymeric separator employed in Li-S cells. Thus, the addition of ACAT significantly ameliorates the electrochemical performances of Li-S batteries due to reduced LiPS migration. In order to further improve the sieving capability, an ultra-thin carbon layer is coated onto to the polymeric separator where the narrower and more tortuous migration routes greatly limit the movement of the bulky ACAT-LiPS complexes. Moreover, the additional conductive coating layer acting as an upper current collector also boosts the electrochemical performance. Accordingly, with the beneficial effects of ACAT and the coated separators, the cells display improved electrochemical performance and stable cyclability for 500 cycles. This new concept offers a promising strategy to achieve practically viable Li-S batteries.
8:00 PM - ES04.10.17
Carbon Fiber Composite Protective Layer for Lithium Metal Secondary Batteries
Danoh Song 1 , Dahee Jin 1 , Seok Woo Kim 1 , Hyunkyu Jeon 1 , Jinkyu Park 1 , Yong Min Lee 2 , Myung-Hyun Ryou 1
1 Chemical and Biological Engineering, Hanbat National University, Daejeon Korea (the Republic of), 2 Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu Korea (the Republic of)
Show AbstractDue to the urgent need for the development of large and middle scale batteries such as electric vehicles (EVs) and energy storage systems (ESSs) requiring high-energy density, the development of stabilized lithium (Li) metal electrodes will have a significant impact on the secondary battery market. Despite Li metal anodes must be a promising anode material for high-energy density batteries, they could not be implemented in the market because of safety issue and poor cycle performance. To overcome these bottlenecks, the suppression of uncontrolled dendrite growth is prerequisite.
To stabilize the Li metal surface, two surface coating approaches were recently reported; Li+ ion conductive inorganic/organic composite protective layers [1] and the fibrous metal felt on Li metal [2]. The primary goal of the first approach was to physically inhibit the Li dendrite and the goal for the second approach was to active a porous, dead Li layer formed on the Li metal surface after repeated cycles.
Taking into account two advantages of each approach, namely, a lightweight composite protective layer with high electric conductivity, we introduced a carbon fiber based composite layers (CCL) on Li metal surface. CCL was fabricated by casting the coating slurry consisting of carbon fiber, electrolytes, and polymeric binders. CCL efficiently suppressed the dendrite formation because the carbon fibers in CCL have a large surface area reducing the current density and Li ions were densely deposited on the Li metal surface. Furthermore, the CCL activated a dead Li layer formed on the Li metal after repeated cycles. As a result, the unit cells consisting of the CCL/Li metal anodes and LiMn2O4 cathodes showed improved cycling performance compared to bare Li metal-based unit cells. The effect of CCL on Li metal was investigated by using a scanning electron microscopy (SEM), galvanostatic cycling test, and electrochemical impedance spectroscopy (EIS).
References
[1] Hongkyung Lee et al., A simple composite protective layer coating that enhances the cycling stability of lithium metal batteries. SCIENTIFIC REPORTS, 2016, 6, 30830
[2] Hongkyung Lee et al., Structural modulation of lithium metal-electrolyte interface with three-dimensional metallic interlayer for high-performance lithium metal batteries. Journal of Power Sources, 2015, 284, 103-108
8:00 PM - ES04.10.18
Lithium-Sulfur Batteries with the High Sulfur Loading/Content and Low Electrolyte/Sulfur Ratio
Sheng-Heng Chung 1 , Arumugam Manthiram 1
1 Texas Materials Institute, The University of Texas at Austin, Austin, Texas, United States
Show AbstractThe limitations of the charge-storage capacities of insertion-compound cathodes in developing high-energy-density lithium batteries have created great interest in conversion-reaction cathodes. With no restrictions in maintaining their initial structure during discharge/charge, the high-capacity sulfur cathodes enable a full two-electron redox reaction per atom and therefore offer an order of magnitude higher theoretical capacity (1,672 mAh/g) than the currently used insertion-compound cathodes. Additionally, sulfur is abundant and environmentally benign. However, as a promising post lithium-ion battery technology, the sulfur cathodes suffer from low electrochemical utilization, poor cycle life, and severe self-discharge arising from the insulating nature of sulfur and the irreversible relocation of polysulfides within the cells during cycling (dynamic) and resting (static).
Currently, the primary focus of lithium-sulfur battery research should be on the design of high-performance sulfur cathodes that exhibit high electrochemical efficiency and stability with the sulfur loading and content as high as possible along with low electrolyte/sulfur (E/S) ratio. Unfortunately, a vast majority of the literature data on low sulfur loading/content and high or unspecified E/S ratio makes it a daunting challenge for developing practically viable Li-S technology.
With a concerted and systematic investigation, we present here an advanced sulfur cathode architecture with a graphene/cotton-carbon substrate with bifunctionality to attain high sulfur loading (45 mg/cm2) and sulfur content (80 wt.%) with a low electrolyte/sulfur ratio of 5. Benefiting from a unique cell-design criterion, the graphene/cotton-carbon cathodes enable a systematic investigation into their high-sulfur-loading capability and low electrolyte feasibility during cell cycling and resting. The high-loading/content graphene/cotton-carbon cathodes cycled at C/10 and C/5 rates deliver peak charge-storage capacities of, respectively, 925 and 765 mAh/g. These values at C/10 And C/5 rates translate into high areal, gravimetric, and volumetric capacities of, respectively, 43 and 35 mAh/cm2, 648 and 536 mAh/g, and 1067 and 881 mAh/cm3 with a stable cyclability over 100 cycles. The high-loading cathodes also demonstrate superior cell-storage capability with a low self-discharge. They display 97 % capacity-retention rate, a long shelf-life of half a year, and stable cyclability after the cell storage.
8:00 PM - ES04.10.20
Hybrid Silicate Coatings for Stable Lithium Metal Anodes
Fang Liu 1 , Yunfeng Lu 1
1 , University of California, Los Angeles, Los Angeles, California, United States
Show AbstractLithium metal anodes , with the highest theoretical capacity and lowest electrochemical potential, has become one of the most promising candidates for next–generation rechargeable batteries. However, implication of lithium metal anodes has been hampered by the unstable electrochemical behavior. Herein, we report the fabrication of hermetic coatings of hybrid silicate on lithium metal surface using a simple vapor deposition technique under the ambient condition. Such coatings consist of a “hard” inorganic moiety that helps to suppress lithium dendrites and a “soft” organic moiety that enhances the toughness. Lithium–metal batteries, including Li–LiFePO4 and Li–S batteries, made with such coated anodes show significantly improved lifetime. This work provides a simple yet effective approach to stabilize lithium metal anodes for high performance lithium metal batteries.
8:00 PM - ES04.10.21
Three-Dimensional Interconnected Conductive Network with High Areal Li2S Loading for Lithium-Sulfur Batteries
Donghuang Wang 1 , Jiangping Tu 1
1 School of Materials Science and Engineering, Zhejiang University, Hangzhou China
Show AbstractNowadays, lithium-sulfur (Li-S) batteries have been regarded as one of the most promising next-generation rechargeable batteries, owing to their high theoretical specific capacity (1672 mAh g−1), high energy density （2600 Wh kg−1）, low-cost and abundant resources. However, Li-S batteries for the commercial application is still hindered by several problems, namely insulativity of sulfur, “shuttle effect”of polysulfides and large volume expansion of ~80%, which lead to low coulombic efficiency and fast capacity fade. In addition, sulfur cathodes should be paired with metallic lithium, which tends to form dendrites and eventually cause an internal short, resulting in terrible safety problems. Therefore, researchers focus on the fully lithiated state of sulfur-lithium sulfide (Li2S), as it can paired with metal-free anodes without safety problems such as graphite, silicon and Sn. In addition, Li2S not only has a high theoretical specific capacity of 1166 mAh g−1 but also has a high melting point of 938°C. Moreover, conversion from Li2S to S company with volume shrinkage, which will creates enough space for volumetric expansion and make the structure more stable as well. However, similar to sulfur cathodes, the Li2S cathodes suffer low conductivity of Li2S, low active material loading and polysulfide dissolution. Consequently, it is important to introduce Li2S into three dimensional conductive network for high performance Li-S batteries. Herein, we construct a 3D conductive network as a novel current collector for high loading Li2S through a facile liquid solution-evaporation. The 3D interconnected conductive network not only possesses a hierarchical architecture with abundant macroporous channels and a high surface area, which provides enough reaction sites to load and stabilize high-loading Li2S, but also improves the electronic conductivity of Li2S and demonstrates pronounced electrochemical performance with enhanced cycle stability with a good capacity retention.
8:00 PM - ES04.10.22
Interfacial Electron Transfer Involving Vanadium and Graphene Quantum Dots for Redox Flow Battery
L Robart 1 , Kalathur Santhanam 1
1 , Rochester Institute of Technology, Rochester, New York, United States
Show AbstractThe redox flow batteries constitute an important class of energy storage devices for variety of applications such as in green grid and stationary applications. In this class of batteries a large number of redox couples have been examined in the past. The vanadium redox couple, although is attractive for this application, suffers from a) poor charge transfer characteristics b) electrode degradation and c) deteriorating performance. We wish to report here that all these deficiencies have been overcome by using a graphene quantum dot electrodes. This electrode has the advantage of large surface area, high electrical and thermal conductivity (1-3). The cell voltage of 1.5 V and power density of about 120 mW/cm2 and coulombic efficiency of 90% can be achieved as the redox couples, V(IV)/V(V) and V(III)/V(II) undergo fast electron transfer at the interface of the quantum dots and solution resulting in higher reversibility. The cyclic voltammetric experiments carried out with quantum dots in the solutions during the oxidation of V(IV) show enhanced currents, due to the movements of the dots which is conducive for power gain in the battery operation. The electrochemical degradation is absent with the quantum dot electrode. Vanadium redox battery is projected for power systems in the range of 100 kW to 10 MW. The charge/discharge cycles conducted over a period of two weeks show high reproducibility.
------------------------------------------------------------------------------------------------------------------------------
1. A.K. Geim and K.S. Novoselov, Nat. Mater., 6, 183–191 (2007).
2. K.S.V. Santhanam, S.Kandlikar, V. Mejia and Y. Yue, US patent US20160017502A1 (2016)
3. Z. Protich, P. Wong and K.S.V. Santhanam, Journal of Power Sources 332 (2016) 337-344.
8:00 PM - ES04.10.23
Microwave-Assisted Synthesis Providing Crystallite Size Control—Impact on Electrochemistry
Jianping Huang 1 , Amy Marschilok 1 , Esther Takeuchi 1 2 , Kenneth Takeuchi 1
1 , Stony Brook University, Stony Brook, New York, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States
Show AbstractThis work demonstrates a faster synthetic approach for bimetallic polyanionic materials which also provides the opportunity for tuning of electrochemical properties through control of material physical properties such as crystallite size. Silver vanadium phosphorus oxide, Ag2VO2PO4, is a promising cathode material for Li batteries due in part to its large capacity and high current capability. A new synthesis of Ag2VO2PO4 based on microwave heating will be presented, where the reaction time can be reduced by approximately 100× relative to other reported methods. Notably, the crystallite size is well controlled via synthesis temperature, showing a linear correlation of crystallite size with temperature. Under galvanostatic reduction, the material with the smallest crystallite size delivers the highest capacity and shows the highest loaded voltage. Further, pulse discharge tests show a significant resistance decrease during the initial discharge coincident with the formation of Ag metal. Additional electrochemical measurements indicating a quasi-reversible redox reaction involving Li+ insertion/deinsertion will also be discussed.
8:00 PM - ES04.10.24
Rate Capability of Lithium Storage in Tunnel Structured Manganese Oxide Improves with Atomic-Level Conductivity Promoted by Surface Silver
Paul Smith 1 , Alexander Brady 1 , Seung-Yong Lee 2 , Andrea Bruck 1 , Lijun Wu 2 , Yimei Zhu 2 , Amy Marschilok 1 , Esther Takeuchi 1 2 , Kenneth Takeuchi 1
1 , Stony Brook University, Stony Brook, New York, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States
Show AbstractCurrent protocols for evaluating energy storage materials involve preparing electrodes as composite slurries with carbon and binder additives for electrical percolation and mechanical stability, respectively. The consideration of bimetallic silver-containing active materials which can provide conductivity at the atomic level through design is relevant. As an example, insulating Ag2VO2PO4 cathodes in absence of other additives form an electrical percolation network upon reduction-displacement of merely 0.3% of total Ag+. Inspired by the silver-vanadium based cardiac defibrillator battery cathode which electrically percolates via an in-situ formed matrix of Ag metal formed through a electrochemical reduction displacement reaction, we have studied the extension of this principle to the 2x2 tunnel structure α-MnO2, which efficiently binds Ag+ within the tunnel. The electrochemistry of α-MnO2 in Li batteries is influenced by several variables because thermal stability, crystallinity, and quantity of defects all potentially vary with Ag+ concentration. This presentation will demonstrate that when these parameters are normalized the electrochemical storage capacity of α-MnO2 is most improved depending on the Ag+ binding position. We will discuss numerous factors which influence the formation of Ag metal and the interplay of intraparticle connectivity vs. interparticle connectivity. we have shown here the benefits of surface adsorbed Ag+ to include higher delivered capacity, improved rate capability (2.25x higher energy delivered at fastest rate tested), ~2x decrease in impedance and higher effective Li+ diffusion constants (2-6 fold) ascribed to increased interparticle electrical connectivity within the electrode. This behavior contrasts with the role of Agtunnel, which results in a lowering of delivered capacity as ascribed to extended Ag+ occupation of the manganese oxide framework. This work highlights that, for α-MnO2, Li storage properties are defined by a combination of sufficient surface connectivity and bulk storage sites.
Symposium Organizers
Cengiz Ozkan, University of California, Riverside
Ali Coskun, Korea Advanced Institute of Science and Technology
Ekaterina Pomerantseva, Drexel University
Federico Rosei, Université du Quebec
ES04.11: Supercapacitors II
Session Chairs
Wednesday AM, November 29, 2017
Hynes, Level 3, Ballroom A
8:00 AM - *ES04.11.01
Graphenic Nanocarbon for Miniaturised Supercapacitors on Silicon
Francesca Iacopi 1
1 , University of Technology Sydney, Broadway, New South Wales, Australia
Show AbstractPower sources are some of the most challenging components for miniaturization, due to the typical need for large energy storage volumes and the use of materials and electrolytes not always compatible with integration on a semiconductor platform. In order to fill this gap, we have pioneered a thin film approach to obtain a high surface –area graphenic carbon from a SiC solid source on silicon [1, 2]. The obtained material is very suitable as electrode for supercapacitors. We have demonstrated an all-solid-state device with high cyclability and power densities [3]. This approach is very versatile, as it requires no transfer and no binding agents, while the electrodes can be easily patterned at the wafer-level to fabricate interdigitated 2D and 3D geometries.
[1] Ahmed, M.; Khawaja, M.; Notarianni, M.; Wang, B.; Goding, D.; Gupta, B.; Boeckl, J. J.; Takshi, A.; Motta, N.; Saddow, S. E., Iacopi, F., A thin film approach for SiC-derived graphene as an on-chip electrode for supercapacitors. Nanotechnology. 2015, 26 (43), 434005.
[2] Ahmed, M.; Wang, B.; Gupta, B.; Boeckl, J.J.; Motta, N.; Iacopi, F.; On-silicon Supercapacitors with Enhanced Storage Performance, Journal of The Electrochemical Society, 164 (4) A638-A644, 2017.
[3] Wang, B.; Ahmed, M.; Wood, B.; Iacopi, F. All-solid-state supercapacitors on silicon using graphene from silicon carbide. Appl. Phys. Lett. 2016, 108 (18), 183903.
8:30 AM - ES04.11.02
ALD Alumina Passivated Silicon Nanotrees Electrodes for New Ultrastable Microsupercapacitors
Pascal Gentile 2 , Anthony Valero 1 , Dorian Gaboriau 1 , Dmitry Aldakov 1 , Saïd Sadki 1
2 , University Grenoble Alpes, CEA, INAC, PHELIQS, Grenoble France, 1 , University of Grenoble Alpes, CEA, CNRS, SYMMES, Grenoble France
Show AbstractThe current trend towards miniaturized and autonomous electronic devices requires innovative energy storage solutions. For instance, autonomous micro-sensor networks or implantable medical devices would need a robust power source with high cyclability and a large power density, which might be out of the scope of conventional battery technologies. For such applications, microsupercapacitors (µSCs) are promising alternatives, and their integration “on-chip” could allow significant innovations.1 However, finding a suitable “on-chip” µSCs technology implies addressing key challenges, such as temperature resistance, silicon industry compatibility and good electrochemical performances on a small footprint.
Following this trend, our work focuses on µSCs using highly doped silicon nanowires (SiNWs) and nanotrees2,3 (SiNTs) as current collector. The fine morphological tuning of the nanostructure allowed by the bottom-up approach permits a careful design of the electrodes architectures, with a considerable liberty compared to other techniques. Such latitude allows optimizing porosity and ionic and electronic pathways while keeping robust mechanical performances, depending on the target application or other parameters like surface modification, functionalization by pseudo-capacitive material, electrolyte…
Nanostructures such as SiNWs and SiNTrs demonstrated excellent cyclability with more than 1 million cycles of galvanostatic charge/discharge under a 4 V wide electrochemical windows in EMI-TFSI ionic liquid, with large power densities and good capacitance values.3,4 Moreover, the use of silicon for electrode material allows extremely interesting developments towards “on-chip” integration and potential scale-up production using standard silicon industry processes for small micro-sized energy storage devices.
Furthermore, we have also investigated the impact of the addition of a high-k dielectric layer, such as Al2O3 as protective films on silicon nanotrees. The electrochemical performances was enhanced, allowing symmetric 2 electrodes device to reach an unprecedented cell voltage of 5.5V, improving energy and maximum power densities compared to unmodified nanostructured silicon. The cyclability was also largely enhanced, with only 3% capacitance fade after 106 galvanostatic charge/discharge cycles at 4V, and no degradation even after several 105 cycles over 5V5. In addition, the protective alumina layer makes it possible to use aqueous electrolytes, not usable with crude silicon, in order to significantly increase the capacities of the µSCs from 1mF/cm2 to 10mF/cm2 and open the door to use metal oxides.
Funding project: The “Direction Générale pour l'Armement” (DGA)
Beidaghi, et al Energy & Environ. Sci. 2014, 7 (3), 867-884
Thissandier, F. et al, S. Nano Energy 2014, 5, 20-27
Thissandier, F. et al J. Power Sources 2014, 269, 740-746
Gaboriau D. et al, RSC Advances, 2016, 6, 81017-81027
8:45 AM - ES04.11.03
Hierarchical Patterned Multiscale Pores in Carbon Aerogels—Effects of Facilitating Ionic Transport for Supercapacitors
Tianyu Liu 1 , Feng Zhang 1 2 , Yat Li 1
1 , University of California, Santa Cruz, Santa Cruz, California, United States, 2 Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng China
Show AbstractIncreasing charge storage capability during fast charging (at ultrahigh current densities) has been a long-standing challenge for supercapacitors. The charge storage capability of supercapacitors in general decreases significantly when increasing the charging rate, which can be ascribed to sluggish ionic transport in micropore-dominated or stochastic diffusion channels of the electrode materials. In this presentation, a methodology on creating multiscale pores (size spanning from sub-nanometers to more than 100 micrometers) assembled in a hierarchical pattern to address the aforementioned challenge will be presented. Experimental results display that the 3D carbon aerogel containing the multiscale pores achieves a remarkable gravimetric capacitance of 374.7 ± 7.7 F g–1 at a current density of 1 A g–1. More significantly, the aerogel retains 235.9 ± 7.5 F g–1 (60% of its capacitance at 1 A g–1) at an ultrahigh current density of 500 A g–1, which outperforms most other state-of-the-art carbon-based supercapacitor electrodes.
A number of techniques have been applied to reveal the mechanism of the synthesized carbon aerogel’s outstanding capacitive performance. For example, electron microscopy and liquid nitrogen sorption studies are carried out to present the porous morphology. Electrochemical techniques including cyclic voltammetry, Galvano-static charge and discharge experiments as well as electrochemical impedance spectroscopy are used to study the electrochemical behaviors. In addition, a systematic comparison between the multiscale porous carbon aerogels and other similar carbon aerogels with different porous morphologies elucidates the different roles of the multiscale pores in facilitating ionic transport. All the aforementioned results will be thoroughly interpreted and supplemented with key conclusions. This presentation will provide insights and strategies on how to achieve ultrafast ionic transport for high power electrochemical energy storage devices, and is expected to attract both experimentalists and theorists in the energy storage research community.
9:00 AM - ES04.11.04
Enhanced Cycle Performance of MnO2 Supercapacitors by Ultrasonic-Assisted Electrodeposition
Jikang Liu 1 , Cheng Xu 1
1 , Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo China
Show AbstractAmong the various inexpensive and environmentally friendly candidates for supercapacitors, MnO2 has been investigated extensively due to its outstanding comprehensive performance. However, MnO2 exhibits poor cycle performance in many research work, which may possibly due to the dissolution of MnO2 during charge-discharge cycles. In this work, we report a facile and effective method to improve the cycle performance of MnO2 films by ultrasonic-assisted electrodeposition.
The MnO2 films were electrodeposited on Ni foam substrates without treatment, with post-ultrasonic treatment and synchro-ultrasonic treatment. The structures of the MnO2 films are characterized by SEM and TEM. MnO2 nanowire clusters and nanosheet arrays can be observed in the samples prepared by post-ultrasonic assisted and synchro-ultrasonic assisted electrodeposition, respectively, while irregular nanosheets are inspected in the samples without ultrasonic assistance. The electrochemical testing of cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements show typical pseudocapacitive behaviors for all samples. Directly electrodeposited MnO2 film without ultrasonic assistance suffers from obvious attenuation in capacitance, which decreases about 37% from 230 F g-1 in 3000 cycles. Comparatively, the ultrasonically treated MnO2 films exhibit a maximum specific capacitance of 369 F g-1 and 325 F g-1 at 1 A g-1, respectively, which can maintain 98% and 86% up to 3000 cycles, respectively. The effects of the deposition current and ultrasonic time were also investigated. The enhancement in electrochemical performance is significant for the samples with ultrasonic-assisted treatment, suggesting the treated MnO2 films to be a promising choice for supercapacitors.
9:15 AM - ES04.11.05
A Sphere-Like Spongy SnO2/ZnO/Carbon Fiber as High-Performance Anode Materials for Electrochemical Supercapacitor
Hai Li 1 , Zexiang Chen 1 , Yan Wang 1 , Zhenkai Peng 1 , Tao Lei 1 , Jijun Zhang 1 , Xinyu Yan 1
1 , School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu China
Show AbstractWe report the synthesis of a spongy SnO2 on carbon fibers as anode material for electrochemical supercapacitor by an electrodeposition method. ZnO is first electrodeposited on carbon fibers as precursor and morphology control agent. Then, SnO2 is electrodeposited to form the spongy structure. Benefited from the large specific area of SnO2 and good electrical conductivity of carbon fibers and ZnO, the SnO2/ZnO/Carbon fiber exhibit a performance of 400 C/g and 70% retain after 300th cycle. And the material shows a nearly -1.0v (vs Hg/HgO) discharge voltage.
Batteries with excellent multiplying performance are attracted for use in high power facilities like electric vehicles. Lithium batteries are widely used nowadays. Compared with lithium-ion battery, aqueous electrochemical supercapacitor shows its advantages in safety, high power density and low cost. However, aqueous electrochemical supercapacitor always shows a low voltage and limits its use in the many fields. To develop new kind materials with high voltage is important.
Many materials are promising as anode materials of electrochemical supercapacitor, such as V2O5, Co(OH)2, ZnO, SnO2 and so on. For the evitable conversion of crystal structure in the charge-discharge process, metal hydroxide, mental oxide or metal sulphides will undergo a huge volume change in the process and make electrical contact worse for the material fall off. Porous material with hierarchical structure is an available way to solve the volume change problem.
For the sphere-like spongy SnO2/ZnO/Carbon fiber structure, it presents the following interesting advantages: 1) Carbon fiber can substitute for substrate materials when assembled in a battery, so it can efficiently reduce the mass of battery, and enhances the integral energy density; 2) Electrodeposition of ZnO and SnO2 provides an easy and low energy consumption method to prepare anode and benefits the mass product of industry; 3) The spongy structure can provide a large specific surface area and corresponding better contact with electrolyte, which make it easy to achieve a better performance of energy and power density. The prepared SnO2/ZnO/Carbon fiber structure can also be used in many other carbon-metal composites, like nickel, cobalt, copper and so on. This SnO2/ZnO/Carbon fiber structure and the preparation method also provide a promising pathway for use in many field like catalysts, sensors, and other devices.
9:30 AM - ES04.11.06
Free-Standing Two-Dimensional MoS2 Nanosheet/Acitvated Carbon Clothes Composite for High Performance of Supercapacitor
Fitri Sari 1 , Jyh-Ming Ting 1
1 , National Cheng Kung University, Tainan Taiwan
Show AbstractTwo dimensional (2D) MoS2 nanosheet has been successfully grown on Activated Carbon Clothes (ACC) by facile method, microwave assisted hydrothermal at a shorter time. We have investigated the growth mechanism at different time reactions and their performance as electrode material of supercapacitor. Scanning electron microscopy (SEM) confirmed that time reaction controls the morphology and growth orientation of MoS2. On the other hand, it was found from the X-Ray Photoelectron Spectroscopy (XPS) that the additional phase which is MoO3 was formed during the reaction. This phase contribute to the performance by giving an additional pseudocapacitance. Furthermore, the intimate contact between MoS2 and ACC favor for fast electron transport during the charge and discharge. As a result, MoS2/ACC composite shows an excellent performance with specific capacitance of 230 F g-1 at scan rate of 5 mV s-1 in 1M H2SO4. Noteworthy, by growing MoS2 on ACC, the specific capacitance of MoS2 is 913.7 F g-1 which is the highest that ever been reported. Furthermore, this free standing material is a promising material for a flexible supercapacitor.
Keywords: MoS2, microwave-assisted hydrothermal, composite, supercapacitor
9:45 AM - ES04.11.07
MOF-Derived Nickel and Cobalt Metal Nanoparticles in a N-Doped Carbon Matrix of Coconut Leaf Sheath Origin for High Performance Supercapacitors and OER Catalysis
Anjali Jayakumar 1 , Jun Zhao 1 , Rajini P Antony 2 , Lee Jong Min 1
1 , NTU- Singapore, Singapore Singapore, 2 Chemistry Department, Bhabha Atomic Research Centre, Mumbai India
Show AbstractBiomass energy is believed to be a major solution to our energy crisis, which is looming in to the near future. While finding sources of energy, it is equally important to find sources of energy storage systems as well, which can cater to the needs of our mankind in all wakes of life, ranging from our day to day activities to use in even desolate places, for the population is ever increasing, that even the most isolated places are occupied nowadays for want of space. Although the batteries have been available as major players with large energy densities, supercapacitors are believed to be the saviours of our future with their high energy and power densities, that will enable us to meet the growing energy requirements. Using biomass as a starting material for developing energy storage materials has a double advantage of utilizing and clearing away waste materials for an advanced and noble purpose such as energy storage. We have employed a simple process to incorporate nickel and cobalt metal nanoparticles in a N-doped carbon matrix obtained from coconut leaf sheath and have tested it for supercapacitor applications and as a catalyst for oxygen evolution reactions.
Coconut leaf sheath-derived nitrogen doped carbon framework is developed and incorporated with nickel and cobalt metal nanoparticles in the carbon matrix by a facile process of growing ZIF-67 metal organic framework particles on the graphitised carbon, followed by annealing it in inert atmosphere. Various parameters, such as the annealing and activation temperature used in the preparation of the samples and amount of nitrogen doped carbon used for loading the nickel cobalt nanoparticles, are modified to obtain three different samples. The samples obtained are then tested for high performance supercapacitors and as an oxygen evolution reaction (OER) catalyst. The optimised sample NiCo-C-1 gave an ultrahigh specific capacitance of 2471 Fg-1 at a current density of 1 Ag-1 in a 2 M KOH electrolyte. An asymmetric supercapacitor assembly prepared from NiCo-C-1 as the positive electrode and the nitrogen doped carbon as the negative electrode, exhibited an energy density of up to 31.8 WhKg-1 for a high power density of 6.2 kWKg-1 over a potential window of 0 to 1.55 V. The two of our best samples were also tested for OER, giving good water oxidation kinetics, revealed by their lower Tafel slopes in the range of 107 mVdec-1 and a low over potential (η) of around 420 mV at a current density of 10 mA cm−2. The process involves minimum chemicals for the pre/post treatment of the biomass and is very crucial as it yields an unprecedented performance for a material majorly developed and modified from biomass. Hence, this work opens great avenues for biomass-derived materials for high performance supercapacitors and catalysis.
ES04.12: Electrode Materials I
Session Chairs
Cengiz Ozkan
Ekaterina Pomerantseva
Wednesday PM, November 29, 2017
Hynes, Level 3, Ballroom A
10:15 AM - *ES04.12.01
Silicon/Graphite Anode High Energy Cells with Improved Efficiency and Cyclability
Jun Wang 1 , Weidong Zhou 1 , Chris Marsh 1 , Xianxing Shi 2 , Paul Gionet 1 , Ronnie Wilkins 1 , Paul Graham 1 , Hong Yan 2 , Huimin Wang 2 , Derek Johnson 1
1 , A123 Systems, LLC, Waltham, Massachusetts, United States, 2 , A123 Systems Asia Co., Ltd., Hangzhou China
Show AbstractFuture generation of high energy density Li-ion batteries call for high specific capacity anode and cathode active materials. Increasing nickel content in the NCM cathode materials has being actively pursued as an effective way to reach higher energy density; similarly, high specific capacity alloy anodes have attracted numerous attentions as another to push the energy density limit. Introducing silicon into the graphite matrix would significantly increase energy at cell level, which is a promising route to deliver higher energy density. However, very high irreversible capacity loss (ICL) has been frequently observed in Si anode based cells. The root causes are fundamentally tied to large volume expansion of alloy type active materials as well as unstable SEI formation. A number of techniques have been studied in order to reduce the ICL for alloy anodes, such as anode prelithiation and surface modification.
This study focused on evaluating a few competitive Si anode prelithiation methods including stabilized Li metal powder (SLMP®), ultrathin Li foil and electrochemical process. Standard single layer pouch electrochemical test vehicles were constructed to evaluate the impact of anode prelithiation. Our results indicated that anode prelithiated with SLMP showed some level of columbic efficiency gain but accompanied with high through-resistance thus cell impedance, which adversely affected cell rate capability and cyclability. By contrast, the ultrathin Li foil as well as the electrochemical process demonstrated significant reduction of ICL with positive impact on cycle life. For the SiOx/graphite anode, approximately 8~10% efficiency gain can be readily realized with cycle life identical or better than those non-prelithiated. We also demonstrated that the outcomes of the prelithiation process can be strongly affected by conditions associated with the prelithiation operation. By carefully optimizing those parameters, some promising results were achieved at single layer pouch cell level with the SiOx/graphite and are now being applied to build high energy cells with improved capacity, energy density and cyclability.
10:45 AM - ES04.12.02
Towards Stable Lithium Metal Anodes—Minimizing the Volume Change by Stable Hosts Designs
Dingchang Lin 1
1 , Stanford University, Stanford, California, United States
Show AbstractLithium (Li) ion batteries have gained grand commercial success as the dominating power source for portable electronics and electric vehicles. Li metal, due to its highest theoretical capacity (3860 mAh/g) and lowest electrochemical potential (-3.040 V versus Standard Hydrogen Electrode), is widely recognized as the most prominent candidate for the next-generation high-energy Li battery anodes. There are, however, at least two major hurdles before Li metal anodes can become viable: exaggerated Li dendrite deposition with explosion hazards and poor cyclability. Behind these problems, we have identified that the infinite relative volume change of Li during cycling plays the key role. Here, we will present a new class of composite Li metal electrodes that exhibits either highly reduced or negligible volume change during electrochemical cycling enabled by stable hosts with lithiophilic surface. The composites also help homogenize the Li-ion flux by the three-dimensional form of Li. Moreover, the surface of highly-reactive Li metal is passivated by advanced nano-engineering, which further suppressed side reactions within electrolyte environment. The composites afford excellent electrochemical cyclability with constant low polarization and negligible nucleation energy. The new design principle offers important insights and exciting opportunities down the road to practical and stable Li anodes.
11:00 AM - ES04.12.03
Electrochemically Induced Phase Evolution of Lithium Vanadium Oxide—Complementary Insights Gained via Ex Situ, In Situ and Operando Experiments, Density Functional Theory and Continuum Modeling
Qing Zhang 1 , Nicholas Brady 4 , Kevin Knehr 4 , Alexander Brady 1 , Christopher Pelliccione 1 , David Bock 2 , Andrea Bruck 1 , Jing Li 1 , Venkata Siva Varun Sarbada 3 , Robert Hull 3 , Eric Stach 2 , Kenneth Takeuchi 1 , Esther Takeuchi 1 2 , Alan West 4 , Ping Liu 2 , Amy Marschilok 1
1 , Stony Brook University, Stony Brook, New York, United States, 4 , Columbia University, New York, New York, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States, 3 , Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractLi1.1V3O8 is a high capacity (362 mAh●g-1) cathode material for Li-ion batteries. The structural evolution during electrochemical discharge and charge processes was investigated using a combination of theoretical calculations and experimental data. Density functional theory was used to predict the intermediate structures at various lithiation states as well as the stability of major phases. In-situ x-ray diffraction (XRD) data was collected as well as operando energy dispersive x-ray (EDXRD) data, allowing the phase transformations to be monitored under load providing both phase and spatial evolution information. Rietveld refinement was performed to fit the diffraction data with the DFT-derived structures and to analyze the fractions of major phases as a function of dis(charge). Further, the electrochemical behavior of LiV3O8 during lithiation, delithiation, and voltage recovery experiments was simulated using a crystal-scale model that accounted for solid-state diffusion, charge-transfer kinetics, and phase transformations. Agreement between the simulated and experimental results is excellent. Thus, by integrating theory and experimental work, a thorough understanding of the evolution of Li1.1V3O8 during electrochemical dis(charge) was obtained.
11:15 AM - ES04.12.04
Electrolytes for Substituted Lithium Cobalt Phosphate High Voltage Cathode Material
Samuel Delp 1 , Jan Allen 1 , T. Jow 1
1 , U.S. Army Research Lab, Adelphi, Maryland, United States
Show AbstractTo improve upon the state of the art lithium ion batteries (LIBs), next generation LIBs must have higher energy density. Higher energy density can be achieved by increasing the specific capacity and/or the working voltage of the cathode active material. One such possibility is LiCoPO4 (LCP) which theoretically delivers 167 mAh g-1 at 4.8 V. Unfortunately, LCP undergoes rapid capacity fading in its pure form. However, the introduction of small quantities of dopants to create a substituted-LCP has greatly increased the cycle life over pure LCP [1].
With the development of new high voltage cathode materials, such as LCP, comes the need for electrolytes that will enable their implementation. Current SOA LiPF6/carbonate based electrolytes are only stable up to ~4.5 V. Two strategies used to increase the electrochemical window of electrolytes include using different solvents such as fluorinated solvents that are stable to higher voltages or using sacrificial additives that undergo reduction/oxidation reactions before the bulk electrolyte does. The latter approach was explored in a recent study using 4.7 V LiNi0.5Mn1.5O4 (LNMO) spinel [2]. Vinylene carbonate (VC), a common additive for SEI formation, did not work with LNMO/graphite cells due to the fact that VC oxidizes at a lower potential than the bulk electrolyte but at a higher potential than SOA cathode materials (>4.2 V) as shown by cyclic voltammetry on glassy carbon electrodes. The oxidation of VC at the cathode prevents its incorporation into the anode SEI layer. Another additive, tris(trimethylsilyl) phosphate showed a similar reduction behavior to VC but was more oxidatively stable. This demonstrated the importance of not only the oxidation stability but also the reduction stability that are both necessary for future electrolytes. The oxidation and reduction stabilities of electrolytes with different additives and combinations of additives using LCP cathode material will be reported.
References
[1] J. L. Allen, J. L. Allen, T. Thompson, S. A. Delp, J. Wolfenstine, T. R. Jow, J. Power Sources, 327, 229 (2016).
[2] S. A. Delp, O. Borodin, M. Olguin, C. G. Eisner, J. L. Allen, T. R. Jow, Electrochimica Acta, 209, 498 (2016).
11:30 AM - ES04.12.05
Artificial SEI Transplantation—Promoting Stable Lithium Metal Cycling in the Presence of Water
Nikhilendra Singh 1 , Timothy Arthur 1 , Kensuke Takechi 1 , Robert Kerr 2 , Patrick Howlett 2 , Maria Forsyth 2
1 , Toyota Research Institute of North America, Ann Arbor, Michigan, United States, 2 , Deakin University, Burwood, Victoria, Australia
Show AbstractThe ability to directly utilize Lithium (Li) metal anodes in rechargeable batteries presents itself as an ideal situation, albeit a challenging one to attain. The use of Li metal as an anode would provide Li batteries with a maximum specific capacity (3860 mAh/g) in comparison to existing commercial anodes (e.g. graphite – 380 mAh/g). Nonetheless, Li metal anodes remain absent in commercial devices due to inherent safety concerns associated with the formation of Li dendrites during practical rate cycling, as well as Li metals’ susceptibility to exhibit high reactivity towards commercially available organic electrolytes. This coupled use of flammable commercial electrolytes and dendrite forming Li metal can adversely feed potential safety concerns, due to possibilities of thermal runaway. Additionally, Li metal is known to react violently with water which is easily found as an impurity in commercially available organic solvents; or passivate in the presence of small quantities of moisture rendering it un-rechargeable. Hence, significant efforts in recent rechargeable battery literature have targeted the development of robust electrolytes, capable of better stability in the presence of Li metal.
To date, the use of solid electrolytes as a mechanical barrier, or the use of specific organic solvent-based electrolytes which control the properties of the solid-electrolyte interface (SEI) are noted observations. Amongst the various classes of Li battery electrolytes developed to date, ionic liquids (ILs) have been utilized as electrolytes which can facilitate enhanced Li cycling efficiencies and favorable Li plating morphologies while being inherently non-volatile/non-flammable alternatives to commercially available organic electrolytes. Within the ILs published to date, combinations of various cations (Imidazolium, Ammonium, etc.) and anions (TFSI, DCA, etc.) have been presented – each with its own distinct advantage. In all, through the capability to combine various cations and anions; the use of such ILs could produce a simpler and perhaps more uniform SEI, resulting in the improved cycling behaviors reported to date.
However, to our knowledge, no reports have shown the capability to sustain dendrite-free Li deposition upon application of practical cycling rates, and allow for stable cycling in the presence of water in the electrolyte. Recently, we reported that certain ILs allowed for successful Li metal cycling in the presence of water mixed into the IL. In recognition of this unique capability, we investigated the protective nature of the IL SEI’s and introduce a new method to artificially form such SEI’s on Li metal. Here, we discuss the various types of ILs capable of Artificial SEI Transplantation (AST) on Li metal, while sustaining dendrite-free Li morphologies at practical cycling rates in the presence of water containing electrolytes. Electrochemical results, along with fundamental analytical analyses will be presented and discussed.
11:45 AM - ES04.12.06
Dead Lithium—Mass Transport Effects on Voltage, Capacity and Failure of Lithium Metal Anodes
Kuan-Hung Chen 1 , Kevin Wood 1 , Eric Kazyak 1 , William LePage 1 , Andrew Davis 1 , Adrian Sanchez 1 , Neil Dasgupta 1
1 , University of Michigan, Ann Arbor, Michigan, United States
Show AbstractImprovement of the performance of Li metal anodes is critical to enable high energy density rechargeable battery systems beyond Li-ion. However, a complete mechanistic understanding of electrode overpotential variations that occur during extended cycling of Li metal is lacking. Herein, we demonstrate that when using a Li metal electrode, the dynamic changes in voltage during extended cycles can be increasingly attributed to mass transport. It is shown that these mass transport effects arise as a result of dead Li accumulation at the Li metal electrode, which introduces a tortuous pathway for Li-ion transport. In Li–Li symmetric cells, mass transport effects cause the shape of the galvanostatic voltage response to change from “peaking” to “arcing”, along with an increase in total electrode overpotential. The continued accumulation of dead Li is also conclusively shown to directly cause capacity fade and rapid “failure” of Li–LCO full cells containing Li metal anodes. This work provides detailed insights into the coupled relationships between cycling, interphase morphology, mass transport and the overall cell performance. Furthermore, this work helps underscore the potential of Li–Li symmetric cells as a powerful analytical tool for understanding the effects of Li metal electrodes in full cell batteries.
ES04.13: Li S Batteries
Session Chairs
Wednesday PM, November 29, 2017
Hynes, Level 3, Ballroom A
1:30 PM - *ES04.13.01
Rational Design of High-Performance S-Based Cathodes—From Structural Confinement to Synergistic Encapsulation of Polysulfides
Zhongwei Chen 1
1 Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
Show AbstractThe fast consumption of fossil fuels and deterioration of environment have stimulated increasing research on efficient energy storage technologies. Lithium-sulfur (Li-S) batteries hold great potential as high-energy power sources towards the applications of electric vehicles (EVs) and largescale grid energy storage, owing to its high theoretical energy of 2600 W h kg-1 that is an order of magnitude higher than that of the current lithium-ion batteries (LIBs). Moreover, such battery technology utilizes naturally abundant sulfur as the cathode material which significantly reduces the cost. However, the major obstacles for the broad implementation of Li-S batteries resides in the fast and dramatic capacity decay. The intermediate lithium polysulfides (LixSn, 3≤n≤8) formed during cycling dissolve in the liquid electrolyte, migrate through the separator, and deposit on Li metal anode, causing “shuttle effect”. In addition, the utilization of the active material is strongly hampered by the intrinsic insulating of S and its discharge product Li2S, leading to a low capacity and poor rate capability. Furthermore, the S cathode suffers from the volume variation (~80%) during lithiation/de-lithiation, causing the loss of electrical contact and the structure instability.
Herein, we demonstrate unique design strategies for the development of high-performance S-based cathodes. Firstly, we design a self-templated hierarchically porous carbon (HPC) frameworks, where the well-defined microporous carbon skeletons and tailored interconnected meso/macropores not only enhance the electric conductivity of the electrode but also effectively and structurally confine the polysulfides within the porous structure. The further introduction of heterogeneous atom into the carbon framework significantly improves the confinement of polysulfides due to the strong interactions; while the combination of carbon nanotubes (CNTs) with metal-organic framework (MOF)-derived HPC enables a self-standing and high-loading S cathode with outstanding cyclability, an excellent high-rate response up to 10C, and an ultra-high volumetric capacity of 960 Ah L-1. Due to the limited confinement ability of HPC, we further develop an innovative strategy to efficiently entrap LixSn from synergistic effect of structural restriction and chemical encapsulation using metal oxide-decorated hollow sulfur spheres. The significance of this strategy lies in that we purposely design a material architecture with both structural and chemical encapsulation effect, and that the material architecture provides a prolonged cycling stability. MnO2 is selected as a model and the MnO2 nanosheets-decorated hollow S spheres (hollow S-MnO2) nanocomposites are achieved through a facile synthesis. The unique material architecture enables high-performance S cathodes with high capacity, high sulfur loading and extremely low capacity decay of only 0.028% per cycle over 1500 cycles at 0.5 C-rate.
2:00 PM - ES04.13.02
Carbon Nanotubes for High Performance Lithium Sulfur Batteries
Jiaping Wang 1
1 , Tsinghua University, Beijing China
Show AbstractCarbon nanotubes (CNTs) play very important roles in the field of lithium batteries. In this talk, research progress on the applications of CNTs as conductive additives and polysulfide-trapping shields will be presented. In one aspect, CNTs were used as conductive additives and growth template for synthesis of nano sulfur−CNT composite material. The conductive CNT matrix not only avoided self-aggregation and ensures dispersive distribution of the sulfur nanocrystals, but also offered three-dimensional continuous electron pathway, provided sufficient porosity in the matrix to benefit electrolyte infiltration, confined the sulfur/polysulfides, and accommodated the volume variations of sulfur during cycling. Furthermore, abundant mesopores were introduced to CNTs through controlled oxidation in air to obtain porous carbon nanotubes (PCNTs). Compared to original CNTs, improved dispersive behavior, enhanced conductivity, and higher mechanical strength were demonstrated in PCNTs. Meanwhile, high flexibility and sufficient inter-tube interaction were reserved in PCNTs to support binder-free and flexible electrodes. High surface area and abundant adsorption points on tubes were introduced, which allowed high sulfur loading, provided dual protection to sulfur cathode materials, and consequently alleviated the capacity fade especially during slow charge/discharge processes. When used as cathodes for Li-S batteries, high sulfur loading of 70 wt% was achieved with excellent reversible capacities, revealing efficient suppression of polysulfide dissolution. Improved high-rate capability was also delivered by the S-PCNT composites, revealing their potentials as high performance carbon-sulfur composite cathodes for Li-S batteries. In another aspect, ultrathin MnO2/graphene oxide/carbon nanotube (G/M@CNT) interlayers are developed as efficient polysulfide-trapping shields for high-performance Li–S batteries. A simple layer-by-layer procedure was used to construct a sandwiched vein-membrane interlayer of thickness 2 μm by loading MnO2 nanoparticles and graphene oxide (GO) sheets on super-aligned CNT films. The G/M@CNT interlayer provided a physical shield against both polysulfides shuttling and chemical adsorption of polysulfides by MnO2 nanoparticles and GO sheets. The synergetic effect of the G/M@CNT interlayer enabled the production of Li–S cells with high sulfur loadings (60–80 wt%), a low capacity decay rate, high rate performance, and a low self-discharge rate with high capacity retention. Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy observations of the Li anodes after cycling confirmed the polysulfide-trapping ability of the G/M@CNT interlayer and showed its potentials in developing high-performance Li–S batteries. These results demonstrate the great potential of CNTs in developing high performance Li–S batteries.
2:15 PM - ES04.13.03
Development of Chemically Immobilized Sulfur Cathodes for Next-Generation Lithium-Sulfur Batteries
Lu Li 1 , Chandra Singh 2 , Wencai Ren 3 , Feng Li 3 , Hui-Ming Cheng 3 , Nikhil Koratkar 1
1 , Rensselaer Polytechnic Institute, Troy, New York, United States, 2 , University of Toronto, Toronto, Ontario, Canada, 3 , Inst of Metal Research, CAS, Shenyang China
Show AbstractLithium sulfur (Li-S) batteries, with specific energy several times higher than that of state-of-the-art Li-ion batteries, have generated great interest and excitement as next generation energy storage systems for portable electronics as well as automotive applications. However, the insulating nature of sulfur/Li2S and the dissolution of lithium polysulfides (LiPSs) in the electrolyte with subsequent parasitic reactions lead to low sulfur utilization and poor cycle life. The integration of nanostructured carbon materials with sulfur is one of the primary strategies for improving the electrical conductivity of the composites and for suppression of the LiPSs shuttle effect through physical confinement. However the weak interaction between non-polar carbon-based materials and polar LiPSs/Li2S species leads to weak confinement and easy detachment of LiPSs from the carbon surface. The resulting diffusion of LiPSs into the electrolyte is responsible for rapid capacity decay and poor rate performance. Here we rationally design and develop chemical immobilizers as sulfur hosts towards building high-performance Li-S batteries. Nitrogen-doped graphene, polar ReS2 nanosheets grown perpendicular to a carbon substrate and few-layer phosphorene nanosheets deposited on a carbon scaffold are employed as highly efficient polysulfide immobilizers and catalysts to significantly accelerate the redox reaction of sulfur species and improve the cycle life of Li-S batteries. A fundamental understanding of the binding energies between LiPSs and chemical adsorbents and the relevant reaction mechanisms in Li-S batteries, can pave the path towards the realization of sustainable and high-performance energy storage technologies.
3:30 PM - ES04.13.04
The Organic/Inorganic Additives for Improving Electrochemical Performance in Li-S Batteries
Jungjin Park 1 2 4 , Chunjoong Kim 3 , Yung-Eun Sung 2 , David A. Shapiro 4 , Jang Wook Choi 1
1 , Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of), 2 , Seoul National University, Seoul Korea (the Republic of), 4 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 , Chungnam National University, Daejeon Korea (the Republic of)
Show AbstractThe limited capacities of the transition metal oxides used as cathodes have created a growing interest in the lithium–sulfur (Li–S) battery because sulfur (S8) units are reduced to dilithium sulfide (Li2S) to give a theoretical capacity of 1675 mA h g−1. However, a principal impediment of the sulfur cathode has been the existence of intermediate Li2Sx polysulfides that are soluble in the organic liquid electrolytes; failure to capture all of the dissolved polysulfides on surfaces electronically connected to the cathode current collector for reversing the reduction reaction rather than poisoning the anode has resulted in a poor cycle life of a Li–S cell. Considerable effort has been devoted to tailoring carbonaceous frameworks and adding carbon interlayers for inhibiting polysulfide dissolution and/or capture of the polysulfides on a surface where the sulfur reduction reaction can be reversed; but this strategy has not been completely successful partly because carbon possesses nonpolar properties, which makes difficult facile adsorption of polysulfides as well as feeble reduction/oxidation of Li2S. With another strategy, several groups have reported that heterogeneous adsorption sites can be provided by metal oxides or sulfides having sulfophilic surfaces. In this study, we designed the organic/inorganic based additives with sulfur to improving electrochemical performance in Li-S batteries.
3:45 PM - ES04.13.05
First Principles Insights into the Molecular Structure and Thermodynamics of Dissolved Lithium Polysulfides in Lithium Sulfur Batteries
Tod Pascal 1 , David Prendergast 1
1 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractCritical to advancements in the recyclability and theoretical capacity of high energy Lithium Sulfur battery is a fundamental understanding of the nature of the molecular species, their equilibrium fluctuations and the role of solvent dynamics in polysulfide dissolution. Due to the inherent difficulties in isolating dissolved polysulfides, experimental electrochemical, calorimetric and spectroscopic methods are limited and difficult to interpret. Here, through the combination of first principles, free energy computer simulations, we present the solubility of isolated lithium polysulfides in two technologically relevant solvents, representing two different regimes of solvation: dimethylformamide (DMF) and bis(2-methoxyethyl) ether (diglyme). We show that the competition between enthalpy and entropy, related to specific interfacial atomic interactions, conspires to increase the relative stability of long chain dianionic species, which exist as Li+– LiSx contact-ion-pairs. Further, we propose a mechanism of radical polysulfide stabilization in simple solvents through the reorientation of the 1st shell solvent molecules to screen electrostatic fields emanating from the solute and explain nonmonotonicity of the dissolution entropy with polysulfide length in terms of a three-shell solvation model. Our analysis provides statistical dynamics insights into polylsulfide stability, useful to understand or predict the relevant chemical species present in the solvent at low concentrations.
4:00 PM - ES04.13.06
In Situ Raman Spectroscopy of Sulfur Speciation in Lithium-Sulfur Batteries
Heng-Liang Wu 1 , Andrew Gewirth 2
1 Center for Condensed Matter Sciences, National Taiwan University, Taipei Taiwan, 2 Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show Abstract
In this talk, in-situ Raman spectroscopy was used to investigate the mechanism of sulfur reduction in lithium-sulfur battery. Raman spectroscopy and cyclic voltammetry obtained from sulfur-carbon cathodes show that long chain polysulfides (S82-) are formed via S8 ring opening in the first reduction process at ~2.4 V vs Li/Li+ and short chain polysulfides such as S42-, S4-, S3.- and S2O42- are observed with continued discharge at ~2.3 V vs Li/Li+ in the second reduction process. These species are reversible during cycling.(1-4) Raman spectroscopy was used to study the reaction kinetics for both short-chain polysulfide formation and S8 decomposition. Rate constants obtained for the appearance and reappearance of polysulfide species show that polysulfide oxidation and reduction is quasi-reversible.
We next propose thiol-based electrolyte additives (biphenyl-4,4’-dithiol (BPD)) to enhance the capacity retention of Li-S batteries. In-situ Raman spectroscopy, In-situ UV-Vis spectroscopy and electrospray ionisation mass spectrometry (ESI-MS) were used to investigate the effect of BPD additive on the sulfur reduction mechanism. Raman spectroscopy and cyclic voltammetry show that an additional reduction process is observed at ~2.1 V vs Li/Li+ with the BPD additive. This reduction is associated with the formation of BPD-polysulfide complexes. The BPD-polysulfide complexes form at ~2.1 V followed by the formation of short chain polysulfides upon further discharge. In-situ UV-Vis spectroscopy shows that the polysulfide solubility decreases in the presence of BPD additive. (-)ESI-MS shows the formation of BPD-S and BPD-S2 and BPD-S3, suggesting that BPD interacts with short chain polysulfides. (5) The formation of BPD-polysulfide complexes decreases the polysulfide solubility and enhances the battery performance.
References:
(1) Barchasz, C. et al., Anal. Chem. 2012, 84, 3973.
(2) Yeon, J.-T. et al., J. Electrochem. Soc. 2012, 159, A130.
(3) Hagen, M. et al., J. Electrochem. Soc. 2013, 160, A1205.
(4) Wu, H.-L. et al., ACS Appl. Mater. Interfaces 2015, 7 (3), 1709
(5) Wu, H.-L. et al., Nano Energy 2017, 32, 50
4:15 PM - ES04.13.07
Rational Design of Cathode Materials for Lithium-Sulfur Batteries—Progress, Challenges and Perspectives
Sarish Rehman 1 , Khalid Mehmood 2
1 , Peking University, Beijing China, 2 Department of Organizational Behavior and Human Resources, School of Management and Economics, Beijing Institute of Technology (BIT), Beijing China
Show AbstractLithium–sulfur batteries (LSBs) are of immense importance because of its high theoretical energy density. Among the existed myriad energy-storage technologies, LSBs show the appealing potential for the ubiquitous growth of next-generation electrical energy storage application. It holds unparalleled theoretical energy density of 2600 Wh/kg, that is almost sixth fold larger than that of conventional lithium-ion batteries (LIBs). Despite its significant advances, multitude issues plague its large-scale implementations: particularly the intrinsic insulating nature of the sulfur (10-30 S/cm), mechanical degradation of the cathode due to large volume changes of sulfur up to 80 % during cycling and loss of active material (producing polysulfide shuttle effect). To tackle the hurdles associated with LSBs, exciting progress has been achieved, however, still, it is a great challenge to mitigate the problems of LSBs and enhance its electrochemical performance. In order, to circumvent the aforementioned challenges, we design unique nanostructures that not only enhance the conductivity of sulfur cathode but also restrain the polysulfide diffusion. We will also discuss the future research directions and the remaining challenging issues in the concluding remarks that pave the ways for further significant progress in this field.
References:
Sarish Rehman, Shaojun Guo, & Yanglong Hou; Rational Design of Si/SiO2@Hierarchical Porous Carbon Spheres as Efficient Polysulfide Reservoirs for High-Performance Li–S Battery; Adv. Materials. 2016, 28, 3167–3172.
Sarish Rehman, Yanglong Hou; Integrated Design of MnO2@Carbon Hollow Nanoboxes to Synergistically Encapsulate Polysulfides for Empowering Lithium-Sulfur Batteries (Just accepted, Small-2017 DOI: 10.1002/smll.201700087.
Sarish Rehman, Kishwar Khan, & Yanglong Hou; Nanostructured Cathode Materials of Lithium-Sulfur Batteries: Progress, Challenges, and Perspectives (Review article Journal of materials chemistry A, 2017,5, 3014-3038 )
4:30 PM - ES04.13.08
Polymeric Sulfur-Graphene Nanocomposites for High Areal Capacity Lithium-Sulfur Batteries
Chi-Hao Chang 1 , Sheng-Heng Chung 1 , Arumugam Manthiram 1
1 , University of Texas at Austin, Austin, Texas, United States
Show AbstractSulfur, which is a major by-product (> 60 million tons per year) from petroleum refinery processes (the hydrodesulfurization procedure), is one of the most abundant element on the earth’s crust. Moreover, because sulfur is able to offer an extremely high theoretical capacity of 1675 mAh/g at low cost, it is being exploited as a cathode material for lithium-sulfur (Li-S) batteries. However, severe fundamental challenges limit the practical viability of Li-S batteries. First, the poor ionic and electrical conductivities of sulfur and the end-discharge product (Li2S) cause low electrochemical utilization. Moreover, the small polysulfide chain intermediates formed during cycling dissolve in the electrolyte and readily migrate through the polymeric separator to the lithium-metal anode, leading to a massive active-material loss and rapid capacity degradation.
This work presents a polysulfur-covalently-grafted graphene nanocomposite (polySGNs), which is employed as an active material to achieve a high-loading cathode and high areal capacity. The well-dispersed highly conductive graphene sheets within the polyS matrix greatly reduce the internal resistance, resulting in much improved electrochemical utilization. Furthermore, the formed organopolysulfide-covalently-grafted-graphene sheets during cycling are selectively sieved by the polymeric separator effectively due to the extremely large aspect ratio (~ 500) of the graphene sheets. Moreover, the organosulfur units can functionalize as “plasticizers” in the discharge sulfide product phase, thereby alleviating the inactive deposition on the electrodes. Hence, the Li-S cells employing the polySGNs as the active material exhibit a high areal capacity of 12 mAh/cm2 and a high capacity retention of 67% for 100 cycles in spite of the high sulfur loading of 10.5 mg/cm2.
4:45 PM - ES04.13.09
Passivating Lithium Metal Anode via Atomic Layer of MoS2 for High Performance Lithium-Sulfur Batteries
Eunho Cha 1 , Wonbong Choi 1
1 , University of North Texas, Denton, Texas, United States
Show AbstractIt is no secret that lithium (Li) metal is considered an optimal anode material for the next-generation high-capacity batteries such lithium-sulfur (Li-S) or lithium-air (Li-O2) batteries. However, the practical use of Li metal in energy storage application is debated due to the parasitic growth of Li dendrites and high reactivity of Li with electrolyte and other active species generated during charge-discharge cycles. Several approaches have been attempted to suppress the growth of such dendrites and to protect Li surface from corrosion; however, challenges including repetitive kinetic reactions of polysulfides at the anode still exist leading to an increase in electrode impedance that hinders the practical applications of Li-S batteries. Here, we utilize an atomic layer two-dimensional MoS2 as a protective layer for Li metal anode. With the Li-intercalated atomic layer of MoS2 formed, the surface of Li metal is stabilized by regulating the concentration and flow of Li ions that triggers dendrite growth. Thus, stable Li electrodeposition is realized with the nucleation sites for dendrite growth inhibited. Our method to control the growth of Li dendrites is analyzed by the diffusion mechanism of Sand’s time with Li deposition, where the MoS2 layer suppresses such nucleation of Li dendrite by facilitating uniform Li deposition. The assembled Li-S cell utilizing the MoS2 coated Li anodes and the 3D carbon nanotube-sulfur cathodes provided superior electrochemical performance; it operated at a high specific energy density with excellent capacity retention as well as with an average Coulombic efficiency of ~98%. The improvement in cycle life and the suppression of lithium dendrite growths through the passivation of Li metal electrodes reveal a new direction for the advancement of Li metal anode in rechargeable batteries. The results also indicate that the atomic 2D layer of MoS2 is a new class of protective materials for Li anodes showing promises to improve the safety and energy density of Li-S batteries.
ES04.14: Poster Session III
Session Chairs
Thursday AM, November 30, 2017
Hynes, Level 1, Hall B
8:00 PM - ES04.14.01
Wood-Derived N-Doped Porous Carbon as Free-Standing Electrodes for Li-O2 Batteries
Jingru Luo 1 , Xiahui Yao 1 , Lei Yang 2 , Yang Han 2 , Liao Chen 2 , Xiumei Geng 2 , Vivek Vattipalli 3 , Qi Dong 1 , Wei Fan 3 , Dunwei Wang 1 , Hongli Zhu 2
1 , Boston College, Chestnut Hill, Massachusetts, United States, 2 , Northeastern University, Boston, Massachusetts, United States, 3 Chemical Engineering , University of Massachusetts Amherst, Amherst, Massachusetts, United States
Show AbstractPorous carbon materials are widely used in Li-O2 batteries to ensure a facile Li+ and O2 diffusion. However, most commercially available porous carbon materials are in particulate form and need to be bound together as an electrode. The inactive polymeric binders not only increase the weight and volume of the devices but sometimes introduce unexpected side effects. Here we developed a wood-derived free-standing porous carbon electrode with neither binders nor additional current collector for Li-O2 battery applications. Wood provides an ideal platform toward free-standing porous carbon with its structural integrity and the spontaneously formed hierarchical pores. The structure is expected to facilitate both mass transport and discharge product storage. Heteroatom (N) doping further improve the catalytic activity of the carbon cathode with lower overpotential and higher capacity. The battery based on the free-standing wood-derived N-doped porous carbon cathode affords a stable energy efficiency of 65% and can be operated for 20 cycles at a discharge depth of 70%.
8:00 PM - ES04.14.02
Development of POMA/PTAA Layer-by-Layer Films as Active Material for Electrochromic Devices
Ernesto Pereira 1 , Wania Christinelli 1
1 , Federal University of Sao Carlos, Sao Carlos Brazil
Show AbstractBesides those need concerning the energy conversion and storage, there are many different forms to save energy in the society. Among then, smart windows which control the amount of light in buildings has become an important alternative. A large class of optically active materials have been proposed to be applied in electrochromic windows, and among them, conducting polymers are a promising choice. These materials change their color upon reversible electrochemical redox cycles, which changes also their electronic properties, such as electronic conductivity. Coupled to the electronic redox reactions, there are ion intercalation (deintercalation) to compensate the generated charges and which are described as the slow step during the redox reaction. As consequence, there are several papers in the literature aiming at to optimize the redox reaction rate to improve the electrochromic device properties. In the present work, we investigate the electrochromic properties of layer-by-layer poly(o-methoxyaniline)-poly(3-thiophene acetic acid), POMA/PTAA, films and compare then with POMA films prepared by casting. The main technique used to characterize the materials has been the potentiostatic steps, between -0.2 V and 0.5 V, and collecting both, the current density and the optical density, measured at 700 nm, during the experiments. The results have shown that the changes in the optical densities for the LBL POMA/PTAA films are larger than those observed in POMA casting ones. Besides, the rate of the change is faster for the LBL material. In this last sense, the optical density change period has been 1 s for the pure POMA film while it is 0.4 s for the LBL one. A second effect is that, considering the same charge, there is a variation of 26 % in the transmittance for POMA film while it is 46 % for the LBL POMA/PTAA one. A third important effect is an increase of the change in the optical density as the number of bilayers is increased for the LBL films. Unexpected, for pure POMA sample, there is a decrease in the optical change as the film mass is increased. Probably, this last effect is a consequence of the decrease in the ion intercalation rate or even a deactivation of the deep portion of the film, under the experimental conditions used during the potentiostatic step. As described above, LBL film presents a different behavior. It is described in previous papers that this material, LBL POMA/PTAA, present self-doping effect. In this sense the ion intercalation total amount decreases significantly due to the self-doping effect which means an interaction between H+ and COO- groups in the PTAA polymer, and the amine (or imine) groups in POMA chains. Finally, there is an important increase in the optical and electrochemical results upon continuous cycling. Under this condition, the LBL film remains optically and electrochemically stable for at least 3000 cycles.
8:00 PM - ES04.14.04
Mechanical Degradation and Optimization of Solid Electrolyte Interphases in Li-Ion Batteries
Jung Hwi Cho 1 , Ravi Kumar 1 , Anton Tokranov 1 , Xingcheng Xiao 2 , Brian Sheldon 1
1 , Brown University, Providence, Rhode Island, United States, 2 Global R&D Center, General Motors, Warren, Michigan, United States
Show AbstractThe stability of the solid electrolyte interphase (SEI) is critically important in rechargeable Li-ion batteries. In particular, the volume changes that occur in the active electrode materials during lithiation and delithiation can create significant mechanical deformations in SEI layers. It is difficult to probe the mechanical response of the SEI directly in complex electrode microstructures that consist of powdered active components and other constituents. However, thin films provide an opportunity to investigate fundamental processes more directly. This approach has been used to investigate SEI formation on silicon and carbon electrodes. To accomplish this, we employed in situ stress, AFM, conventional in situ electrochemistry, and ex situ surface characterization. These experiments allowed us to investigate SEI behavior in different electrolytes and with different cycling conditions. Significant differences between Si and graphitic carbon were observed in SEI growth and passivation mechanism. Both the electrolyte composition and the formation conditions had significant effects on the SEI structure and properties. The results from these experiments and corresponding models also suggest that stresses can be engineered during SEI formation, to enhance the electrochemical and mechanical integrity of these critical passivation layers.
8:00 PM - ES04.14.05
Comparative Study of NMC 622 and NMC 811 Cathode Materials for Lithium-Ion Battery
Fredrick Omenya 1 , Hui Zhou 1 , Natalya Chernova 1 , Chengcheng Fang 2 , Byoung-Sun Lee 2 , Ping Liu 2 , Y. Shirley Meng 2 , M. Stanley Whittingham 1
1 , Binghamton University, Binghamton, New York, United States, 2 , University of California, San Diego, La Jolla, California, United States
Show AbstractLiCoO2 has conquered the cathode market for lithium ion batteries; recently the mixed transition metal oxide lithium nickel manganese cobalt dioxide have gained attention due to their superior electrochemical properties, better thermal stability, and lower cost. Nickel-rich compositions of lithium nickel manganese cobalt oxide (NMC) have been developed as promising high-energy, high-voltage and improved rate cathode materials capable of significantly increasing the energy density of lithium-ion batteries.
Here we report a systematic comparative study on rate capability, charge discharge behavior and nickel/lithium mixing of the two nickel-rich layered oxides, NMC622 and NMC811. The results showed that both NMC622 and NMC811 have pure hexagonal layered structure with Ni/Li mixing below 4%. Both samples have similar specific capacity of about 220 mAh/g at current densities, C/10; however, NMC811 demonstrated superior electrochemical performance compared to NMC611 at higher rates. The NMC622 sample showed a strong dependence on the electrode loading, higher electrode loading above 15 mg/cm2 had poor performance compared to lower loadings at the same current density in mA/cm2 while NMC811 sample does not show such loading dependence. This work was supported by the DOE-EERE-Battery500 consortium.
8:00 PM - ES04.14.07
Gel Electrolyte Based Supercapacitors with Higher Capacitances and Lower Resistances than Devices with a Liquid Electrolyte
Belqasem Aljafari 1 , Arash Takshi 1
1 Electrical Engineering, University of South Florida, Tampa, Florida, United States
Show AbstractRecently, gel polymer electrolytes (GPEs) have been drawn noteworthy attention for different applications, specifically, for supercapacitors. GPEs could become an excellent substitute to liquid electrolytes (LEs) for making flexible and more durable devices. The performance of two different electrolytes (GPEs and LEs) in multi-wall carbon nanotube based supercapacitors were investigated. In spite of significantly lower conductivity of GPEs than LEs, devices with the gel electrolyte presented a superior performance. More focus has been given in this work on demonstrating the performance of supercapacitors based on GPEs and LEs at different concentrations of the acids. The GPEs were made from the composition of polyvinyl alcohol (PVA) and phosphoric acid (H3PO4) or sulfuric acid (H2SO4) at different concentrations ranging from 1 M to 3 M. The LEs were aqueous H3PO4 or H2SO4 solutions at the same range of different concentration as well. Both electrolytes have been characterized at room temperature by making supercapacitors and using cyclic voltammetry, charging-discharging, electrochemical impedance spectroscopy, and leakage tests. The experimental results showed that GPE devices had much better capacitances and resistances compare to the LE based devices. Besides, at 1 M concentration, the electrolyte resistance (RS) of the gel electrolyte was roughly same as RS of liquid electrolyte. However, at 3 M concentration, the RS based on the gel electrolyte was even much lower than RS that based on the liquid electrolyte. Moreover, the capacitance of the H3PO4 gel electrolyte based device was increased from 21.87 mF to 38.6 mF with the increase in the concentration from 1 M to 3 M. On the other hand, the parallel and series resistance values of the H3PO4 gel electrolyte was decreased with the increase in the concentration recording 71.7 Ω and 69.269 Ω, respectively. The promising results from the gel electrolytes are encouraging for further development of flexible and high capacitance energy storage devices.
8:00 PM - ES04.14.08
Characterization of Furfural Resin- and Phenol Resin-Based Active Carbon Surfaces and Electric Double Layer Capacitor Properties
Takeyasu Saito 1 , Takafumi Nakazawa 1 , Shinichiro Suzuki 1 , Naoki Okamoto 1 , Isamu Ide 2 , Masanobu Nishikawa 2 , Yoshikazu Onishi 2
1 , Osaka Prefecture University, Sakai Japan, 2 , LIGNYTE. CO.,LTD, Sakai Japan
Show AbstractElectric double layer capacitor (EDLC) has been attracted much attention as one of the most promising high power and durable energy storage devices. However, low energy density is the major drawback, therefore, the optimization of active carbon specific surface area, mesoscale pore volume and electrostatic capacity should be necessary.
In this study, we prepared thermosetting resin-based active carbon particles (phenol resin and furfural resin, 10μm in diameter). Then we investigated that relationship surface structure by Boehm's method as well as XPS and capacitor properties. The summary is the followings. The CO2 activation after KOH activation widened a hole size in both resin. Raman spectroscopy showed active carbon prepared from Furfural and Phenol resin having lower crystalline. Furfural resin had higher specific capacity per weight at the high current density than Phenol resin . KOH+CO2 activation to Phenol resin is a good method for producing resin based carbon high specific capacity. Specific capacity per weight was increased with high activation temperature (850°C) in both resin based active carbon. Specific capacity increased by acid treatment and deterioration during cycle test was not observed. The effects of surface organic groups on capacitor proerties will be discussed.
8:00 PM - ES04.14.09
Formation of 2D Paper-Like Co2P as an Efficient Catalyst for Hydrogen Evolution Reaction
Zhiling Du 1 , Xing Lu 1
1 , Huazhong University of Science and Technology, Wuhan China
Show AbstractTwo-dimensional have attracted increasing research interest in electrochemical energy storage and water splitting. Herein, we succeeded in synthesizing two-dimensional Co2P with nanopaper structure using water-soluble salt sodium chloride as template and Cobalt acetate anhydrous and sodium hypophosphite as cobalt source and phosphorus source, respectively. The obtained paper-like Co2P material shows wonderful catalytic performance in water splitting for hydrogen gas in 0.5 M H2SO4 aqueous solution. The test results reveal that paper-like Co2P requires a low onset overpotential of 52.0 mV and a small Tafel slope of 57.7 mV dec-1. Moreover, when the current density of electrode is up to 20 mA cm-2, the needed overpotential is merely 123.0 mV, and the overpotential only increased 10.0 mV after 22 h stablity operation. So the paper-like structural Co2P may be a potential candidate as a low cost electrocatalyst in hydrogen evolution field.
8:00 PM - ES04.14.10
CuGeO3/Graphene Hybrid Electrocatalysts for Lithium-Air Batteries
Gwang-Hee Lee 1 , Seung-Deok Seo 1 , Dong-Wan Kim 1
1 , Korea University, Seoul Korea (the Republic of)
Show AbstractLi-air batteries operate via the reversible oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) (i.e., 2Li + O2 + 2e− ↔ Li2O2, E0 = 2.96 V versus Li/Li+) at the surface of a porous cathode, which can achieve energy densities (> 3500 W h kg-1) several times greater than those exhibited by Li-ion batteries. Electrocatalysts in the cathode can improve the efficiency of discharge–charge cycling through ORR and OER. Carbon-supported precious metals (Pt/C, Ir/C, and Ru/C) have been investigated as effective electrocatalysts to promote the ORR/OER. However, most of precious metal-based electrocatalysts are expensive and offer poor cycle stabilities. Recently, transition metal oxides have attracted interest to replace precious metal based electrocatalysts.
In this work, we investigated graphene/CuGeO3 hybrid structures as electrocatalysts. Graphene/CuGeO3 hybrid structures were prepared using one-pot hydrothermal process. Graphene/CuGeO3 hybrid structures were formed via the hybridization of 1D CuGeO3 nanorods and 2D graphenes. We discuss their electrocatalytic activities through the series of electrochemical properties such as cyclic voltammetry, galvanostatic cycling, and rate capability, compared with CuGeO3 nanorods. Excellent electrochemical performance was achieved when graphene/CuGeO3 hybrid structures were loaded in cathodes. This efficient electrocatalytic activity could be associated with well-ordered 1D/2D hybrid structures. Furthermore, electrochemical impedance spectroscopy was employed to investigate the electrochemical rechargeability by the oxygen reduction and evolution kinetics.
8:00 PM - ES04.14.11
A Combined Theoretical-Experimental Investigation of Energy Storage Behavior of Reduced Graphene Oxide/Manganese Oxide Supercapacitor
Chan-Woo Lee 1 , Segi Byun 2 , Byung-Hyun Kim 1 , Kanghoon Yim 1 , Jungjoon Yoo 3
1 Research and Development Platform Center, Korea Institute of Energy Research, Daejeon Korea (the Republic of), 2 Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of), 3 Separation and Conversion Materials Laboratory, Korea Institute of Energy Research, Daejeon Korea (the Republic of)
Show AbstractElectrochemical capacitors including micro-supercapacitors, have drawn valuable attention as a new class of micro-power sources. However, they have limited their applications in micro-energy storage due to their low volumetric energy densities. Here, compact structured Birnessite (KMnO2)/reduced graphene oxide (RGO) hybrid films consisting of multi-valent Mn ions were prepared via a two-step fabrication process involving a simple chemical redox reaction and post-thermal annealing to form a multi-layer structured film. With this versatile method, GO sheets can act as either a growth template for the highly capacitive KMnO2 nanosheets or as a mechanical support for the production of compact hybrid films. Enhanced electrochemical characterization of the KMnO2/RGO hybrid film revealed a remarkable ultrahigh volumetric capacitance (493 F/cm3 at 10 mV/s), ultrahigh energy and power density (13.3 mWh/cm3 at 2.5 A/cm3 and 22.6 W/cm3 at 58 A/cm3, respectively) and a semi-permanent cycle life (97% capacitance retention) in an aqueous electrolyte system.
We also investigated atomic-level reaction mechanisms of the KMnO2/RGO capacitor using density-functional theory calculations with KMnO2 /RGO interface models. Various materials properties of KMnO2/RGO including stoichiometric deviation, energetics of various defects, electron redistribution, local atomic environments (e.g. coordination number of Mn) have been explored in atomic level.
8:00 PM - ES04.14.12
Spontaneously Exfoliating Functionalized Graphene
Intak Jeon 1 , Timothy Swager 2
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractAdvances in graphene science and technology depend critically on finding and manipulating new forms of graphene into functional materials. Covalent chemical modification of the π-electron system of graphene leads to profound changes in its properties and is crucial for the broad class of materials with new enhanced functionalities. The manipulation of pristine graphene has been challenging since the material is insoluble in water and organic solvents and the van der Waals energy stored in π–π stacked graphenes within a graphite crystal is relatively huge and difficult to overcome. Here we show a room temperature (RT) method for breaking a wide area network of van der Waals coupling between graphene galleries (d001 > 15.3 Å) and subsequent spontaneous exfoliation of electrochemically functionalized graphene. The electrochemical reductive intercalation does not cause any irreversible lattice damage to the hexagonal carbon plane. Subsequently, this material is activated and can undergo spontaneous exfoliation with diazonium ions to produce graphene with high functionalization densities. Whole exfoliated and functionalized graphenes without the need for a centrifugation and or decantation steps (which causes limit analysis for only small quantity of graphene dispersion) were evaluated.
8:00 PM - ES04.14.13
Bivalence Mn5O8 with Hydroxylated Interphase for High-Voltage Aqueous Sodium-Ion Storage
Xiaoqiang Shan 1 , Xiaowei Teng 1
1 , University of New Hampshire, Durham, New Hampshire, United States
Show AbstractAqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (∼1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn5O8 pseudocapacitor electrode material with a well-ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge–discharge cycles. The interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn5O8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn2+/Mn4+ redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn5O8.
8:00 PM - ES04.14.14
Hybrid Na-Air Batteries Based on an Acidic Catholyte—Understanding the Effects of Catholyte pH and Flow
Soo Min Hwang 1 , Youngsik Kim 1 2
1 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of), 2 Energy Materials and Devices Lab, TOONE Corporation, Ulsan Korea (the Republic of)
Show AbstractRechargeable batteries based on metal-air chemistries have attracted great interest because of their high theoretical energy density, which is crucial to electrification of vehicles and storing renewable energy for peak-load shifting at grid scale. Nevertheless, many challenges remain for their practical implementaion in ambient air. Aprotic metal-air batteries typically suffer from intrinsic issues, such as (i) coverage of the air-cathode surface by the formation of insoluble, insulated discharge products (metal oxides) and (ii) side reactions with moisture and CO2 introduced from ambient air, which impede long-term cycling stability of the cells. An effective way to elude the issues is to employ a hybrid electrolyte system consisting of a superionic conducting solid electrolyte sandwiched between two different types of aqueous and non-aqueous electrolytes. This hybrid-type concept for metal-air enables protection of the reactive metal anode and organic electrolyte from deleterious H2O and CO2 in ambient air and induces soluble discharge products (metal hydroxides) on the air-cathode.
In this study, we investigated a hybrid-type Na-air battery using a Na superionic conducting solid electrolyte (Nasicon, Na3Zr2Si2PO12), which separates the Na metal anode in a non-aqueous electrolyte from the air-cathode immersed in an aqueous electrolyte (catholyte) in ambient air. We examined the effects of the catholyte pH and flow on the battery performance. By using an acidic catholyte composed of 1 M NaNO3 and 0.1 M citric acid (pH=~1.8) and a flow-through configuration, Na-air cells showed an increased operation voltage. When a cell employed state-of-the-art oxygen electrocatalysts, such as Pt/C and IrO2, on the air-cathode, it exhibited a reduced voltage gap of ~0.4 V between the charge (~3.7 V) and discharge (~3.3 V) voltages vs. Na+/Na at a current density of 0.1 mA cm-2 over 20 cycles (200 h total). These results demonstrate that the hybrid Na-air cells based on an acidic catholyte and a flow-through mode could be a promising way toward the practical realization of Na-air batteries.
Acknowledgements
This work was supported by the 2017 Research Fund (1.170012.01) of UNIST (Ulsan National Institute of Science and Technology).
8:00 PM - ES04.14.15
Doping of Layered Li(NixMnyCo1−x−y-zMz)O2 (z=Ag,Cu) Cathode Materials for Lithium-Ion Batteries
Berke Piskin 2 1 , Cansu Savas 2 , Mehmet Kadri Aydinol 2 , Fatih Piskin 2
2 Metallurgical and Materials Engineering, Middle East Technical University, Ankara Turkey, 1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractIn our daily life, we are increasingly dependent on technology and technological devices. For this reason, the importance of Li-ion batteries has been preserved day by day, and the research done about them has become more comprehensive and important. Therefore, many devices that require power we use in daily life and also newer applications such as such as electric vehicles (HEVs), power backup, and portable power tools require high energy density with high charge and discharge, rate capability. Note that the capacity of the currently used layered LiCoO2 cathodes is limited to perform 50% of its theoretical capacity (140 mAh/g)1. There has been effort on the related LiNi0.5Mn0.5O2 due to its lower cost and environmentally and highest theoretical capacity among layered oxides. However LiNi0.5Mn0.5O2 cathode material suffers from an 8-10% Li/Ni exchange which was thought to be detrimental to high-rate performance. Moreover, olivine LiFePO4 and spinel LiMn2O4 cathode materials also do not exhibit enough gravimetric and volumetric energy densities2. In this regard, novel layered Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathode materials have been investigated as an alternative cathodes searching for higher capacity, cycle life, rate capability and safety. Li(Ni1/3Mn1/3Co1/3)O2 cathodes exhibit higher capacity that of close to 200 mAh/g with enhanced safety3. For this purpose, the precursor powders were prepared using aquaous solution via spray pyrolysis. Details of production method has already been mentioned in our previous work4. From previous work, it was decided to work on cathode materials named as Li(Ni1/3Mn1/3Co1/3)O2 (111), Li(Ni0.2Mn0.2Co0.6)O2 (226), Li(Ni0.6Mn0.2Co0.2)O2 (622). Ag and Cu were used, with 2 wt.% ratio, as doping elements to decrease the amount of Co element in all layered cathode materials. X-Ray Diffraction (XRD) pattern of obtained undoped and doped 111, 226 and 622 cathode material showed good [006]/[102] and [108]/[110] doublets indicating layered structure and good hexagonal ordering. There were no observable morphological changes for undoped and doped cathode materials analyzed by scanning electron microscopy (SEM) however improvements on electrochemical propoerties, especially on cyclability, have been observed.
1. Goodenough, J. B. & Park, K.-S. The Li-Ion Rechargeable Battery: A Perspective. J. Am. Chem. Soc. 135, 1167–1176 (2013).
2. PAN, C. et al. Influences of transition metal on structural and electrochemical properties of Li[NixCoyMnz]O2 (0.6≤x≤0.8) cathode materials for lithium-ion batteries. Trans. Nonferrous Met. Soc. China 26, 1396–1402 (2016).
3. Buchberger, I. et al. Aging Analysis of Graphite/LiNi1/3Mn1/3Co1/3O2 Cells Using XRD, PGAA, and AC Impedance. J. Electrochem. Soc. 162, A2737–A2746 (2015).
4. Piskin, B. & Aydinol, M. K. Development and characterization of layered Li(NixMnyCo1−x−y)O2 cathode materials for lithium ion batteries. Int. J. Hydrogen Energy 41, 9852–9859 (2016).
8:00 PM - ES04.14.16
Micronized Ge-Based Anodes for High-Energy Lithium-Ion Batteries
Chanhoon Kim 1 , Gaeun Hwang 2 , Ji-Won Jung 1 , Su-Ho Cho 1 , Jun Young Cheong 1 , Sunghee Shin 2 , Soojin Park 2 , Il-Doo Kim 1
1 Materials Science and Engineering, Korea Advanced Institute of Science and Engineering (KAIST), Daejeo Korea (the Republic of), 2 Energy Engineering, Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
Show AbstractThe ever-increasing demand for electric vehicles and large-scale energy storage systems, lithium-ion batteries (LIBs) require substantially enhanced energy densities. Ge has intensively received attention as a promising anode material for high-energy LIBs due to its significant advantages such as high volumetric capacity of 7366 Ah L −1, high electrical owing to its small band gap of 0.6 eV, high Li+ diffusivity, and isotropic lithiation behavior, leading to the highly reversible capacities, while minimizing fracture failures in the Ge-based anodes. However, the Ge anodes mainly suffer from extremely large volume expansion (261%, for Li3.75Ge at room temperature) during the lithiation process, accompanying a large strain, leading to the pulverization of electrode materials and electrical isolation from conductive network, resulting in rapid capacity degradation.
The nanostructuring of Ge has significantly contributed to alleviating the huge volume expansion problem of the Ge anodes. However, the practical use of nanostructured Ge anodes has still been hindered due to several problems including a low tap density, poor scalability, and severe side reactions. Therefore, micrometer-scale Ge-based materials possessing high capacity and structural durability are desirable for practical application for high-energy LIBs.
Here, micronized Ge3N4 with a high tap density of 1.1 mg cm−2 has been successfully developed via a scalable wet oxidation and a subsequent nitridation process of commercially available micrometer-sized Ge as the starting material. This micronized Ge3N4 has multiple advantages: i) highly suppressed volume expansion of 27% compared to micrometer-sized Ge (92%) at fully lithiated state; ii) significant improved rate capability after carbon coating process due to the high electrical conductivity; iii) high reversible capacity of 924 mAh g−1 (2.1 mAh cm−2) with high mass loading of 3.5 mg cm−2; iv) stable capacity retention reaching 91% of initial capacity after 300 cycles at a rate of 0.5 C. We further demonstrate the effectiveness of Ge3N4@C as practical anodes in full cell configuration with commercial cathodes (LiCoO2). The full cells show stable cycle retention and especially excellent rate capability retaining nearly 50% of its initial capacity at 0.2 C for 12 min discharge/charge condition.
8:00 PM - ES04.14.17
Fabrication of Carbon Nanotube Based Sulfur Cathode for Lithium Sulfur Batteries
Keisuke Hori 2 , Kei Hasegawa 2 , Suguru Noda 2 1
2 Department of Applied Chemistry, Waseda University, Tokyo Japan, 1 Research Institute for Science and Engineering, Waseda University, Tokyo Japan
Show AbstractThe lithium-sulfur battery has much attention due to its high gravimetric energy density (2600 Wh kg
-1), which is three to five times higher than commercialized batteries (LiC
6 - LiCoO
2: 400 - 600 Wh kg
-1), owing to the high theoretical capacity of sulfur (1675 mAh g
sulfur-1). On the other hand, the lithium-sulfur battery has several problems: the low electric conductivity, the volume change (up to 179%) during cycles, and the dissolution of intermediates products called lithium polysulfides (Li
2S
x) into many electrolyte. Much effort has been put to solve these issues, and reports have showed excellent results [1]. Nevertheless, the amount of sulfur loading in electrode is limited [2]. In recent years, 3D current collector such as metal foam, and graphene foam has been used to increase sulfur areal loading. Carbon nanotube (CNT) is also a candidate for 3D current collector, which can provide high areal loading of sulfur. However, reported work have low gravimetric capacity because of poor electric path, and low volumetric capacity due to the excess void space [3].Therefore, S/CNT electrode with high gravimetric and volumetric capacity is strongly required.
In this work, the electrode with high mass fraction and tap density is fabricated by simple fabrication process. Furthermore, the interface control between CNT and sulfur can make high reaction area and dense film, which lead to high gravimetric, volumetric, and areal capacities.
Submillimeter-long few-wall CNTs produced by fluidized-bed chemical vapor deposition method [4] were dispersed with surfactant solution. Then, the solution was vacuum filtrated, and 30-μm-thick CNT paper was fabricated. S/CNT cathodes with 30−80 wt% sulfur content were prepared by the sublimation method, followed by pressing process. The electrochemical analysis was conducted with 1 M lithium bis(trifluoromethanesulfonyl)imide and 0.2 M LiNO
3 in 1,2-dimetethoxyethane and 1,3-dioxolane (v:v=1:1) as the electrolyte and the lithium metal foil as the anode. The S (60 wt%)/CNT electrode showed a high initial discharge capacity of 1060 mAh g
sulfur-1, 700 mAh g
electrode-1, 1.8 mAh cm
-2, and 840 mAh cm
-3 at initial cycle. Furthermore, capacity retention of 85% was achieved after 100 cycles.
References:
[1] A. Manthiram, et al., Chem. Rev., 114, 11751, (2014)
[2] M. Hagen, et al., Adv. Energy Mater., 5, 1401986, (2015)
[3] Q. Pang, et al., Nature Energy 1, 16132, (2016)
[4] Z. Chen, et al., Carbon, 80, 339, (2014)
Corresponding Author: S. Noda
Tel&Fax: +81352862769
Email:
[email protected]Web: http:www.f.waseda.jp/noda/
8:00 PM - ES04.14.18
Self-Powered Textile for Wearable Electronics by Supercapacitor and Wireless Charging System
A Young Choi 1 , Changsoon Choi 2 , Seon Jeong Kim 2 , Youn Tae Kim 1
1 Department of IT Fusion Technology, Chosun University, Gwangju Korea (the Republic of), 2 Department of Biomedical Engineering, Hanyang University, Seoul Korea (the Republic of)
Show AbstractA wearable energy source with high flexibility and light weight can be integrated with a textile platform. Wearable electronics require dedicated power sources. Currently, supercapacitor is considered the most important energy-related technology due to the possibility of replacing the batteries or extending the lifetime of a battery. In addition, power transmission is one of the most important elements in self-powered wearable electronics. This study presents a set of materials and design concepts for textile-based energy storage and transmission. Highly performing fiber supercapacitors are realized. The utilized strategy was to embed pseudocapacitive guest materials within vascular, electrically conductive, and mechanically strong networks of carbon nanotube (CNT) fibers. More than 90 weight percent of the guest loading was achieved without significantly hindering accessibility of the electrolyte to the guest. In addition, asymmetric electrode configuration that consisted of a manganese dioxide (MnO2) embedded cathode fiber and a reduced graphene oxide (rGO) embedded anode fibers is demonstrated for higher working voltage. The power transmission resonant coils were made of a copper conductive yarn and designed as a planar rectangular spiral array. The number of coil turns was 40 with 0.1 mm line intervals. The measurement results showed a maximum transmission efficiency of 45 %. In the future, the storage and transmission elements will be integrated with each other to form a composite unit of high mechanical robustness. The power transmission can be increased by increasing the resonant frequency of the coils. In addition, an interface element for avoiding over-charging and over-discharging is an important research topic for potential future work.
* This research was supported by the MSIP(Ministry of Science, ICT and Future Planning), Korea, under the ITRC support program (IITP-2015-0-00390), the Creative Research Initiative Center for Self-powered Actuation, and the Basic Science Research Program through the National Research Foundation of Korea (NRF-2017R1A6A3A04004987).
8:00 PM - ES04.14.19
Free-Standing Thin PPY/MnO2 Composite Film Prepared by Interfacial Electrochemical Co-Deposition for Supercapacitor
Hua Zhu 1 , Chuang Peng 1 , Dihua Wang 1
1 Civil Engineering, School of Resources and Environmental Science, Wuhan China
Show Abstractnterfacial electrochemical co-deposition was adopted for synthesis of PPY/MnO2 composites. This synthesis route is capable of producing free-standing ultra-thin films due to the unique self-limited growth at the three-phase interline. The experiment process as follows:
(1)The resulting MnO2 fine power was dispersed in water under sonication to make 1.0 mg/mL aqueous suspension. Perchloric acid was added to the suspension to achieve a molarity of 0.2 M. 10 mL of this suspension was added to a 50 mL colorimetric tube containing 10 mL solution of 0.1 M pyrrole in trichloromethane. After rigorous mechanical shaking, an unstable water/oil emulsion with MnO2 fine powder was formed.
(2)A platinum wire with a diameter of 0.5 mm was immersed across the interface of the mixed solution. A saturated calomel electrode (SCE) and a platinum sheet were used as the reference and counter electrode, both immersed in the aqueous solution, without contact with trichloromethane. The electrodeposition was carried out in both potentiodynamic cyclic voltammetry performed at potential range between -0.2 and 0.7 V) and potentiostatic (0.6 V vs SCE) modes.
(3)The electrochemical characterisation of the composite films was carried out in aqueous solution of LiClO4 (0.5 mol L-1).
Cyclic voltammograms (CV) suggest pure PPY, MnO2 and the composite all exhibited capacitive behaviour between -0.6 and 0.3 V vs Hg / Hg2SO4, due to the compatible potential ranges of PPY and MnO2. The CV curve of the PPY/MnO2 composite electrode is more analogous to a rectangle, indicating more rapid charge-discharge process. The mass specific capacitance of MnO2 PPY and the PPY/MnO2 composite are 76, 118 and 134 F/g, respectively. The composite electrode also showed good supercapacitor behaviour over a wide potential scan range from 5 to 100 mV/s. The charge and discharge segment of the curves also showed high symmetry, suggesting excellent reversibility and high coulombic efficiency. The specific capacitance was calculated as 234 F/g at 0.5 A/g and 113 F/g at 10 A/g, indicating a satisfactory capacitance retention at high current load.
8:00 PM - ES04.14.20
Al Doped NASICON-Structured Na3V2(PO4)3 Cathode with Long Cyclability for Na-Ion Batteries
Pravin N. Didwal 1 , Duc Tung Ngo 1 , Chan-Woo Min 1 , Chan-Jin Park 1
1 , Chonnam National University, Gwangju Korea (the Republic of)
Show AbstractSodium-ion batteries (SIBs) have received much attention for application in energy storage systems (ESSs) owing to their wide availability and economic merit originating from abundant Na resources. However, SIBs face issues in low specific energy, short cycle life, and insufficient specific power due to the heavier mass and larger radius of Na+ ion compared with those of Li+ ion used in conventional Li-ion batteries (LIBs). In particular, the electrochemical performance of SIBs is highly influenced by cathode materials. NASICON-structured Na3V2(PO4)3 (NVP) is a potential cathode material for SIBs: the 3D framework of NVP generates a large interstitial space to supply diffusion path for Na-ions. In addition, NVP electrode shows two potential plateaus at 3.4 V and 1.6 V vs. Na/Na+. In particular, the potential plateau observed at 3.4 V vs. Na/Na+ is relatively higher than that found in other cathode materials for SIBs. However, the distorted VO6 octahedral units in the NASICON structure negatively affects the electronic conductivity. Various strategies such as particle size increase, carbon coating, and metal-ion doping have been adopted to improve the rate capability of NVP. Among the methods, metal-ion doping is commonly envisaged as an efficient way to improve stability, electronic conductivity, and ionic diffusion of NVP. In particular, Al has been proposed as an efficient dopant in many cathode materials due to its low cost, huge availability, and environmentally safe nature. In addition, Al stabilizes the NASICON framework of V2(PO4)3 in the Na-ion exchange process.
In this work, Na3V2-xAlx(PO4)3 (NVAP) with various Al doping contents (x= 0-0.12) were prepared by a simple citric acid assisted sol-gel method. After synthesis, we obtained nano particles of NVAP with a size of ~30 nm. The NVAP electrode exhibited significant improvements in rate capability and cyclability compared with the pure NVP electrode. In specific, the electrode showed a cyclability longer than 500 cycles and a good rate capability at the rates of 0.1C-5C. These enhanced cyclability and rate capability can be attributed to the optimized particle size, structural stability, and enhanced ionic and electronic conductivity resulting from Al doping in NVP.
8:00 PM - ES04.14.21
Carbon Nanofiber-Interface Layer to Enhance the Performance of Lithium-Sulfur Batteries
Duc Tung Ngo 1 , Hanbyeol Kim 1 , Chan-Jin Park 1
1 , Chonnam National University, Gwangju Korea (the Republic of)
Show AbstractLithium–Sulfur battery is regarded as a promising candidate for next-generation rechargeable batteries due to its high theoretical capacity of 1675 mAh g-1, economic merit, and environmental friendliness. However, for convectional Li-S battery systems, the sulfur cathode faces many issues relating to the low intrinsic electronic conductivity and instability of sulfur cathode resulting in the insufficient utilization of sulfur. In particular, the dissolution of the high-order lithium polysulfide intermediates into organic electrolyte leads to low capacity and rapid capacity fading in the batteries. Therefore, for the development of the highly efficient Li-S battery, it is crucial to improve the conductivity of the sulfur cathode and maintain/reuse the soluble lithium polysulfide within the cathode structure. In recent years, a variety of conductive carbon materials with optimal porosity and high specific surface area have been employed as a cathode matrix for hosting sulfur, aiming at improving the electronic conductivity and physically constraining the dissolution of sulfur and lithium polysulfide. Previous studies demonstrated that the use of these approaches resulted in significant improvements in cyclability and capacity of the Li-S battery. Nevertheless, at least 20-30% sulphur has been lost into the electrolyte as a form of polysulfide, especially under the high sulfur loading condition.
In this study, we propose a simple and reliable method for preparing carbon nanofiber as an interlayer between cathode and separator in Li-S battery. The carbon nanofiber interlayer serves to intercept the migrating polysulfide and reuse the trapped active materials, leading to the suppression of the shuttle effect of polysulfide. Accordingly, the capacity and coulombic efficiency of sulfur electrode in the Li-S battery employing carbon nanofiber interlayer were significantly improved compared to conventional Li-S batteries.
8:00 PM - ES04.14.22
Green Synthesis of Alcohol from Oxalic Acid—Influence of Nb-Doping in Anatase TiO2 on Its Electronic Structure and Catalytic Performance
Yu Sun 1 , Masaaki Sadakiyo 1 , Sho Kitano 1 , Xuedong Cui 1 , Miho Yamauchi 1
1 , International Institute for Carbon-Neutral Energy Conversion (WPI-I2CNER), Fukuoka Japan
Show AbstractEfficient energy storage via the conversion of electric powder into high-energy chemicals, so-called energy carriers, is critically important for the practical application of intermittent renewable energies. In our previous work, we discovered that titanium dioxide can electrochemically catalyze the reduction process from oxalic acid to glycolic acid, which was the first demonstration of direct electric powder storage via electro-reduction of a carboxylic acid. However, the low electron transfer properties of TiO2 inhibited its application in fuel-cell systems.
In order to enhance the electron transportation in anatase TiO2, we intentionally doped Nb in anatase TiO2 microstructures due to several reasons: (1) Nb has suitable atomic/ionic radius to replace Ti in TiO2 lattice structure; (2) Nb-doping in TiO2 was documented to be able to reduce the the resistance of TiO2 thin film; (3) The band-gap of Nb2O5 is ~3.4 eV, Nb-doping is supposed to slightly increase the bandgap value of TiO2 (It was revealed in our previous report that slight increase of bandgap value is effective for catalytic efficiency enhancement).
Until now, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmittance electron microscopy (TEM), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and Electron dispersed spectroscopy (EDS) measurements had been carried out in order to reveal the basic properties of our synthesized samples. We discovered that 1) Nb was successfully doped inside the microstructure of TiO2: at lower doping concentration, Nb-doped samples kept the microstructure of anatase TiO2; at higher doping concentration, amorphous powders were obtained; 2) uniform micro-sphere structures in micro-meter size were observed at lower Nb-doping concentration; (3) the band-gap value of Nb-doped was slightly increased according to the UV-vis measurement; (4) Most importantly, electrochemical reduction reaction of oxalic acid was also performed, revealing that 10% Nb-doping in anatase TiO2 gave much better catalytic performance than other samples. Interestingly, we found the color change from white to blue after electrocatalysis by using Nb-doped samples, which is under investigation by XPS and X-ray Absorption Fine Structure (XAFS) measurement. We assume that the color change is related with the change of valence state of Niobium, which may relate to the catalytic performance. In addition, we are measuring the electron transportation properties in order to prove the enhancement of electron transportation and to achieve the final application in flow-cell system.
8:00 PM - ES04.14.23
Rational Design of Carbon Materials for Advanced Lithium-Sulfur Batteries
Ruopian Fang 1 , Feng Li 1 , Hui-Ming Cheng 1
1 Institute of Metal Research, Chinese Academy of Sciences, Shenyang China
Show AbstractLithium-sulfur (Li-S) batteries are currently being explored intensely due to their high theoretical specific energy density and low cost. However, the areal sulfur loading of electrodes is usually less than 2.0 mg cm-2, which leads to low areal capacity that does not even outperform standard Li-ion batteries (4 mAh cm-2), greatly degrading the high-energy advantage of Li-S batteries. Therefore, it is of great importance to develop new materials and structures for the cathode that not only allows a high areal sulfur loading, but also enables high sulfur utilization and good cycling stability.
Here, we report the facile synthesis of a highly porous graphene as the sulfur host, allowing a high sulfur content of 80 wt%, which further enables a high sulfur loading of 5 mg cm-2. From the perspective of integrated structural design of the cathode, we further proposed an all-graphene configuration, in which highly conductive graphene was employed as the current collector, and partially oxygenated graphene was used as a polysulfide-adsorption layer. This unique cathode structural design enables both high initial gravimetric specific capacity and areal specific capacity, together with excellent cycling stability, indicating great promise for more reliable lithium-sulfur batteries.
For conventional 2D sulfur electrodes, increased sulfur loading means increased electrode thickness, resulting in limited kinetics for both lithium ions and electrons. In this regard, using 3D current collectors with interlinked electron and ion channels will be ideal for achieving ultrahigh sulfur-loaded and high performance Li-S batteries. Here, we obtained a hollow carbon fiber foam through a simple and scalable approach using natural cotton as the starting material, then it was used as a 3D current collector to accommodate sulfur nanoclusters within the void space of the conductive scaffold. As a result, high sulfur loadings up to 21.2 mg cm-2 were achieved. Remarkably, a high initial areal capacity of 23.32 mAh cm-2 and excellent cycling stability (~70% capacity retention rate after 150 cycles) were demonstrated. The multiple electron pathways through the electrode contribute to the high sulfur utilization. Our results demonstrate facile fabrication of electrodes with high areal loading of sulfur on a 3D carbonaceous current collector, therefore, would be valuable for the fundamental research and possible commercialization of Li-S batteries.
8:00 PM - ES04.14.24
High Performance Porous Si Anodes by Low Temperature Aluminothermic Reduction of Silica
Xiaolin Li 1 , Kuber Mishra 1 2 , Xiaodong Zhou 2 , Ji-Guang Zhang 1
1 , Pacific Northwest National Laboratory, Richland, Washington, United States, 2 Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina, United States
Show AbstractAmong various nanostructured Si materials, porous Si with well-engineered pore size and porosity has been demonstrated to be promising anode materials for next generation high energy and long life Li-ion batteries. Yet, the high cost and poor scalability of the synthesis approaches such as electrochemical etching and magnesiothermic reactions, greatly hamper the further application of porous Si. Here, we developed a safe and low temperature aluminothermic reaction systems to form porous Si from porous silica precursors. Salt media of low melting point (<300°C) such as ZnCl2 was used by itself or with other salts (e.g. AlCl3) in the form of lower melting point eutectic mixture. The reduction reaction can be initiated at a temperature as low as 210 °C so that the silica precursor’s porous structure can be maintained. The porous Si obtained delivers a high specific capacity of ~2600 mAh/g at the current density of 1.2 A/g. Good capacity retention of >80% after 100 cycles was demonstrated. The reduction reaction also happens using core-shell structured porous SiO2@C. It provides a safe, low cost and scalable way to synthesize high performance porous Si anode materials.
8:00 PM - ES04.14.25
Enhancement of Li-Ion Conductivity in a Mesoporous Silica-Based Solid Nanocomposite Electrolyte
Akihiko Sagara 1 , Mitsuhiro Murata 1 , Morio Tomiyama 1 , Mikinari Shimada 1 , Xubin Chen 2 3 , Knut Gandrud 3 , Maarten Mees 3 , Philippe Vereecken 2 3
1 Advanced Research Division, Panasonic, Osaka Japan, 2 Centre for Surface Chemistry and Catalysis, KU Leuven, Leuven Belgium, 3 , imec, Leuven Belgium
Show AbstractThe enhancement of Li-ion conductivity was demonstrated in a solid nanocomposite electrolyte (SCE) based on a mesoporous silica filled by an ionic-liquid electrolyte (ILE) comprising an ionic liquid and an organic Li-salt. Solid electrolytes with Li-ion conductivity higher than 1mS/cm are needed for the development of solid-state Li-ion batteries. In the last decade, several studies were done on the improvement in ion conductivity through surface enhancement at inorganic oxide surfaces such as silica, alumina or Titania added to, for example, polymer electrolytes. Also, composites of nanoparticles mixed with ILE have been proposed to promote the Li-ion conductivity along the particle surface [1]. However, so far the ionic conductivity was always lower than that of the original ILE due to the interrupted ionic percolation paths from particle to particle.
In this work, a new type of SCE comprising a mesoporous silica and an ILE was developed. The ionic conductivity exceeded that of the similar silica nanoparticle composite electrolyte. The mesoporous silica comprises a plurality of nano-sized pores whose surfaces are covered with the ILE. The Li-ion conductivity is found to be enhanced at the pore surfaces where the ionic liquid molecules are adsorbed into an ordered structure. The change in molecular interactions weakens the association between the Li-ion and its anion and as such the mobility of the Li-ions is enhanced. Furthermore, the interconnected pores in this SCE provide continuous pathways throughout the electrolyte nanostructure, ensuring the full effect of the surface enhancement is observed.
The SCE was fabricated from tetraethylorthosilicate (TEOS) in a well-known single-step sol-gel process. N-buthyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl) imide ([BMP]TFSI) and bis(trifluoromethanesulfonyl)imide lithium salt (LiTFSI) were employed as ILE materials in the same process. The SCE shows an ionic conductivity of close to 1 mS/cm, which is higher than that of a silica nanoparticle composite. In addition, functional solid-state batteries of Li/SCE/Li4Ti5O12 and Li/SCE/LiFePO4 are demonstrated, showing an electrochemical charge-discharge performance.
[1] “Nanocomposite Ion Gels Based on Silica Nanoparticles and an Ionic Liquid: Ionic Transport, Viscoelastic Properties, and Microstructure”, J. Phys. Chem. B 2008, 112, 9013–9019
8:00 PM - ES04.14.27
Understanding the Lithiation/Delithiation Mechanism of Si1-xGeX Alloys
Laura Loaiza 1 , Elodie Salager 3 4 , Nicolas Louvain 2 4 , Athmane Boulaoued 2 5 6 , Antonella Iadecola 4 , Patrik Johansson 6 5 , Lorenzo Stievano 2 4 5 , Vincent Seznec 1 4 , Laure Monconduit 2 4 5
1 Laboratoire de Réactivité et Chimie des Solides (CNRS UMR 7314), Université de Picardie Jules Verne, Amiens France, 3 CNRS, CEMHTI UPR3079, Université d’Orléans, Orléans France, 4 , Réseau sur le Stockage Electrochimique de l’Energie (RS2E), CNRS FR3459, Amiens France, 2 Institut Charles Gerhardt -AIME (CNRS UMR 5253), Université de Montpellier, Montpellier France, 5 ALISTORE European Research Institute, Université de Picardie Jules Verne, Amiens France, 6 Department of Physics, Chalmers University of Technology, Göteborg Sweden
Show AbstractLithium-ion batteries (LIBs) have an important place among energy storage devices due to their high capacity and good cyclability. However, the advancements in portable and transportation applications have extended the research towards new horizons, and today the development is hampered e.g. by the capacity of the electrodes employed. Silicon and germanium are among the considered modern anode materials as they can undergo alloying reactions with lithium while delivering high capacities.The synergetic effect of Si1-xGex alloys has been proven1, the capacity is increased compared to Ge-rich electrodes and the capacity retention is increased compared to Si-rich electrodes, but the exact performance of this type of electrodes will depend on factors like specific capacity, C-rates, cost, etc. There are several reports on various formulations of Si1-xGex alloys with promising LIB anode performance, with most work performed on complex nanostructures resulting from synthesis efforts implying high cost.
In the present work, we studied the electrochemical mechanism of the Si0.5Ge0.5 alloy as a micron-sized electrode formulation using carboxymethyl cellulose (CMC) as the binder2. A combination of a large set of in situ and operando techniques were employed to investigate the structural evolution of Si0.5Ge0.5 during lithiation and delithiation processes: powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Raman spectroscopy, and 7Li solid state nuclear magnetic resonance spectroscopy (NMR).
The results have presented a whole view of the structural modifications induced by the cycling processes. The Si0.5Ge0.5 amorphization was observed at the beginning of discharge. Further lithiation induces the formation of a-Lix(Si/Ge) intermediates and the crystallization of Li15(Si0.5Ge0.5)4 at the end of the discharge. At really low voltages a reversible process of overlithiation and formation of Li15+δ(Si0.5Ge0.5)4 was identified and related with a structural evolution of c-Li15(Si0.5Ge0.5)4. Upon charge, the c-Li15(Si0.5Ge0.5)4 was transformed into a-Lix(Si/Ge) intermediates. At the end of the process an amorphous phase assigned to a-SixGey. Thereby, it was demonstrated that Si and Ge are collectively active along the cycling process, upon discharge with the formation of a ternary Li15(Si0.5Ge0.5)4 phase and upon charge with the rebuilding of the a-Si-Ge phase. This process is undoubtedly behind the enhanced performance of Si0.5Ge0.5 compared to a physical mixture of Si and Ge.
References
1. D. Duveau, B. Fraisse, F. Cunin, L. Monconduit. Synergistic Effects of Ge and Si on the Performances and Mechanism of the GexSi1−x Electrodes for Li Ion Batteries. Chem. Mater. 2015, 27, 3226–3233
2.. L. C. Loaiza, E. Salager, N. Louvain, A. Boulaoued, A. Iadecola, P. Johansson, L. Stievano, V. Seznec, L. Monconduit. Understanding the lithiation/delithiation mechanism of Si1−xGex alloys. J. Mater. Chem. A, 2017. DOI: 10.1039/C7TA02100C
8:00 PM - ES04.14.28
High Performance of Air Electrode Prepared by Low Temperature Roll Press Method for Air Secondary Battery
Masatsugu Morimitsu 1 , Yusuke Ujino 1 , Kenji Kawaguchi 1
1 , Doshisha University, Kyoto Japan
Show AbstractA metal/air battery is one of the promising candidates for a next generation of secondary battery which is possible to show higher energy density than current lithium ion batteries. Especially, the air battery using a metal hydride negative electrode and an alkaline aqueous solution, i.e., metal hydride/air battery, is expected to have such a high energy density and maintain safety even though the battery capacity increases, because the negative electrode uses no less noble metal. This paper presents a novel method to prepare the air electrode and the performance of the obtained air electrode and the MH/air battery. The method comprised low temperature roll press (LTRP) of the components of the air electrode, i.e., carbon powder as the conducting material, bismuth ruthenium oxide as the catalyst, and PTFE as the binder, at 100 oC or less. The obtained air electrode showed a low polarization for oxygen reduction and evolution, especially the polarization at -500 mA/cm2 for oxygen reduction was below 0.5 V. The MH/air battery using the air electrode also gave the reduction in polarization during charge and discharge, resulting in a high energy density more than 800 Wh/L. The effects of the preparation method on the internal structure and polarization behaviors of the air electrode will be discussed in this paper.
8:00 PM - ES04.14.29
Formation and Corrosion Properties of Ni-Pd-Pt-P and Ni-Pt-P Glassy Alloys
El-Sayed Shalaan 1 2 , Akihisa Inoue 1 3 , Fahad Al-Marzouki 1 , Saleh Al-Heniti 1 , Abduallah Obaid 4
1 Physics Department, King Abdulaziz University, Jeddah Saudi Arabia, 2 Physics Department, Suez Canal University, Ismailia Egypt, 3 International Institute of Green Materials, Josai International University, Togane Japan, 4 Chemistry Department, King Abdulaziz University, Jeddah Saudi Arabia
Show AbstractAmong a large number of amorphous and glassy alloys in late transition metal base alloy systems which are one of the most important engineering nonoequilibrium metallic materials, the largest glass-forming ability has been recognized for Ni-Pd-P-B system and the largest diameter reaches 30 mm for Ni60Pd20P16B4, The largest size exceeds significantly those (16 mm) for Fe-, Co- and Fe-Co-based bulk glassy alloys. Besides, the Ni-based bulk glassy alloys exhibit good mechanical properties with large compressive ductility as well as very large supercooled liquid region reaching about 90 K before crystallization. The Ni-Pd-P bulk glassy alloys have also attracted much interest as a raw material for preparing isolated nanoscale fcc-Ni(Pd) particles or nanoporous fcc-Ni(Pd) structure which can be expected to exhibit useful catalytic and electrode characteristics. The atomic scale homogenous dissolution of constituent Ni, Pd and P elements in the glassy phase has enabled the spontaneous formation of such nanoscale fcc-Ni(Pd) structure by applying chemical etching treatment to the Ni-Pd-P bulk glassy alloys. Based on a number of previous data on catalytic and electrode characteristics of nanoscale isolated particles or nanoporous structure, Pt element is also one of the most attractive ones because nanoporous Pt powder has been used as the most important catalytic material in various industries. It is important to reduce Pt content in the nanoporous Pt catalytic powder in the maintenance of good catalytic properties. However, there is no report on the formation of glassy phase in Ni-based alloys containing Pt element as solute element. It is important to develop a new Ni-based bulk glassy alloy containing Pt element and to clarify the fundamental properties of the Pt-containing glassy alloys. This paper aims to examine the formation and corrosion properties of Ni-Pd-Pt-P and Ni-Pt-P glassy alloys and to investigate the possibility of synthesizing nanoporous Ni(Pt) or Ni(Pd,Pt) structure from the Ni-based glassy alloys by chemical corrosive treatment.
8:00 PM - ES04.14.30
Cu, Co-Embedded N-Enriched Mesoporous Carbon for Efficient Bifunctional Oxygen Reduction and Hydrogen Evolution Reactions
Min Kuang 1 , Qihao Wang 2 , Peng Han 1 , Gengfeng Zheng 1
1 Laboratory of Advanced Materials, Fudan University, Shanghai China, 2 Department of Chemistry, Fudan University, Shanghai China
Show AbstractThe development of hybrid, earth-abundant electrocatalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) has attracted substantial research foci to address the global energy and environment challenges. Copper (Cu) has been theoretically proposed to exhibit high reduction capability close to Pt, but its high diffusion behavior at elevated fabrication temperatures limits the homogeneous incorporation of Cu with carbon counterparts. In this work, we developed a Cu, Co-embedded nitrogen-enriched mesoporous carbon framework, via a facile Cu-confined thermal conversion strategy of ZIF-67 polyhedrons in situ grown on Cu(OH)2 nanowires. The ZIF-67 component confines the particle size of Cu nanocrystals at low calcination temperature, which substantially increases the metal and nitrogen doping levels, surface area and porosity, strong synergetic coupling and improved mass transfer, thus enabling excellent ORR and HER electrocatalytic performances. A high half-wave potential (0.884 V vs. reversible hydrogen potential, RHE) and a large diffusion-limited current density (5.4 mA cm-2 at 0.2 V vs. RHE) were achieved for ORR, comparable to or exceeding the best reported earth-abundant ORR electrocatalysts. In addition, a low overpotential (~ 145 mV vs. RHE) at the current density of 10 mA cm-2 was demonstrated for HER, further suggesting its great potential as a bifunctional electrocatalyst for sustainable energy applications.
8:00 PM - ES04.14.31
The Mechanism of Lithium Intercalation into Incommensurate Graphene Layers—A High Capacity Rechargeable Battery Anode
Tereza Paronyan 1 2
1 , University of Louisville, Louisville, Kentucky, United States, 2 , Hexalayer, LLC, Louisville, Kentucky, United States
Show AbstractGraphite, consisting of many commensurately-stacked layers of graphene, has low capacity of intercalating Lithium due to low diffusion within graphite structure. The repulsive interactions that arise within commensurately assembled layers prevent Lithium penetration into the structure. The rotation, or twisting, of adjacent layers result in a weaker interplanar interaction.
Here, we experimentally study the mechanism of Lithium intercalation of an as-grown incommensurate graphene structures. They demonstrate over 1500 mAh/g reversible capacity throughout hundreds of charge-discharge cycles in Li-ion battery cells1. X-ray diffraction and photoemission spectroscopy analysis revealed high intercalation of lithium atoms between graphene layers by forming of up to LiC1.39 stoichiometry without Li plating. The graphene layers were adjusted and remained in AA stacking with interlayer d-spacing of 3.9-4.06Å during the charge and discharge process. Raman analysis shows that 92% of sp2 carbon atoms are Li-absorbed and participate in charge transfer. Graphene structure was fully recovered after de-lithiation, demonstrating a high-intensity 2D band after 100 cycles. In addition to structural and binding analysis, the HRTEM observations confirm that each hexagon of sp2 carbon is occupied by lithium ions in the multilayer configuration. We propose a new lithium insertion model in which the number of graphene layers also affect the charge capacity according to LiN+1C2N formula. The maximum capacity of 1674 mAh/g would be achieved by forming of Li3C4 in bilayer configuration when an infinite stack would approach the LiC2. In fact, the weakened Van der Waals interaction of incommensurate graphene layers enables easy and full penetration of lithium atoms into a multilayer structure, followed by a flexible adjustment of layers with extended interlayer distances with a stable long-term cycling.
An effective capacity increase of over six times compared to commercial graphite cells promises the feasibility of the rapid development of lightweight, cost-efficient, high-capacity rechargeable batteries based on this study.
1Paronyan, T. M. et al. Incommensurate Graphene Foam as a High Capacity Lithium Intercalation Anode. Sci. Rep. 7, 39944; doi: 10.1038/srep39944 (2017).
8:00 PM - ES04.14.32
Self-Assembled Nitrogen Doped Fullerenes and Their Catalysis for Fuel Cell and Rechargeable Metal-Air Battery Applications
Min Ho Seo 3 , Seung Hyo Noh 1 , Choah Kwon 1 , Jeemin Hwang 1 , Takeo Ohsaka 2 , Beom-Jun Kim 3 , Tae-Young Kim 3 , Young-Gi Yoon 3 , Zhongwei Chen 4 , Byungchan Han 1
3 , Korea Institute of Energy Research (KIER), Daejeon Korea (the Republic of), 1 , Yonsei University, Seoul Korea (the Republic of), 2 , Kanagawa University, Kanagawa Japan, 4 , University of Waterloo, Waterloo, British Columbia, Canada
Show AbstractDevelopment of highly active electrocatalysts that are cost competitive takes the center stage in research fields for next-generation electrochemical energy conversion and storage systems like fuel cell and metal-air battery. Regarding the systems for commercialization, there are various challengeable issues, which should overcome sluggish kinetics and stability on the electro-catalyst for the aimed reactions such as oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) occurred in the high over-potential and harsh condition. By applying first principles calculations and state of the art experimental measurements to well-defined model systems of metal and metal oxides and carbon-based material for ORR/OER, we can unveil the fundamental mechanisms controlling the catalytic properties and structural integrity of targeted catalysts. In this report, we discuss the ORR and OER activity and stability for self-assembled nitrogen-doped fullerenes (N-fullerene) as one of the examples with previous history, applying to energy conversion and storage devices such as fuel cells, metal-air batteries systems. We screen the best N-fullerene catalyst at 10 at.% doping level of nitrogen not at previously known 5 or 20 at.% for graphenes. We identify that compressive surface strain induced by the doped nitrogen plays a key role in the fine-tuning of the catalytic activity.
8:00 PM - ES04.14.33
Smart Construction of High Mass Loading Ternary Hydroxides for Energy-Storage Application
Shaoran Yang 1 , Kaili Zhang 1
1 , City University of Hong Kong, Hong Kong Hong Kong
Show AbstractSmartly designed nanoarchitectures with effective hybridization of transition metal oxides/hydroxides are promising to realize high performance electrodes for energy storage devices. However, previous researches rarely acquire the benefits from hierarchical architectures, while maintaining meaningful mass loadings. Also, most of them mainly focus on the resulting improvements of an integrated nanostructure by their electrochemical properties, but studies on formation mechanism and interactions between each components are obscure. In addition, Seed-assisted method is seldomly applied to energy storage materials.
In this study, seed-assisted hydrothermal process is firstly applied to prepare mesoporous Ni-Co-Mn hydroxide nanoflakes (NCMH) on nickel foam with practical mass loadings (higher than 5 mg cm-2). Further mechanism study reveals that the Ni(OH)2 nanorod arrays, which are firstly prepared in a hydrothermal process, serve as seeds for the success deposition of NCMH nanoflakes. Through the convenient and cost effective method, this design results in more orderly spatial distribution, lower intrinsic resistance and shorter electron transport pathways. The proof-of-concept application of NCMH as binder-free supercapacitor electrodes reveals an impressive specific capacitance of 7.51 F cm-2 at a high mass loading of 5.2 mg cm-2. By comparison, pristine Ni(OH)2 nanorod seeds and non-seed-assisted NCMH obtain comparably lower performances of 2.97 and 3.39 F cm-2, respectively. The smart design of as-obtained NCMH exhibiting great potential for energy storage devices and shedding lights on structural design for nanomaterials.
8:00 PM - ES04.14.34
Development of the Aqueous Zinc Nickel Flow Battery with High Energy Density
Jin Liu 1 , Yan Wang 1
1 , Worcester Polytechnic Institute, Worcester, Massachusetts, United States
Show AbstractThe semi-solid flow cell (SSFC) is an attractive design scheme for the redox flow batteries (RFBs). While the capability of conventional RFBs is limited by the solubility of its active couple, the SSFC model utilizes a flow-able slurry to functionalize the solid-state reactions in a fuel cell layout, in which way achieves a much higher loading concentration of the active material and therefore advanced electrochemical properties. Through mixing carbon additives into the electrolyte, electron transfer and ion transfer are simultaneously obtained inside the three-dimension network of the slurry. The research of SSFC has been mainly focused on investigating slurry electrodes for the lithium-ion chemistries and super capacitors in the past years. However, for a larger scale of usage, developing SSFC with a more economical chemistry is also a competitive field to study. Here we update the progress of studying the zinc-nickel flow battery (ZNFB), which was proposed in our lab as an aqueous alkali SSFC system. This report introduces the ZNFB system and updates optimized system with the new design strategy. A new prototype of the cell was proposed and fabricated to get accustomed to the unique characteristics of ZNFB, such as the interactive relationship between ion transfer and electron transfer. The circulation of slurries is enhanced in the new system, which brought the sight of device optimization into the SSFC system, in addition to the material design of the slurry. With the new cell, the Columbia efficiency is improved from 60% to 90% for the cathode slurry, and from 80% to 90% for the anode slurry in half-cell tests. The balance between viscosity (related to the flow-ability) and electrochemical properties (related to raw material selection) is taken into consideration while we further understand the SSFC system. Our results demonstrate this “hybrid” RFB system, which includes the beneficial features of solid-state Zn/Ni batteries as eco-friendly and deposit-abundant, and provides a pathway for the RFB technologies to adapt to the escalation of the power system.
8:00 PM - ES04.14.35
Solid-Solid Interfaces for Suppression of Dendrites in Metal Anode Based Batteries
Zeeshan Ahmad 1 , Venkatasubramanian Viswanathan 1
1 , Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Show AbstractLi metal represents the most promising anode material for Li-based batteries in the quest for higher energy density. However, uncontrollable dendrite growth during cycling has presented a major barrier to achieving the full capacity. Solid electrolytes present a new avenue for tackling the problem of dendrite growth, besides improving the safety of energy storage technology. Mitigating dendrite growth at electrode-electrolyte interfaces requires understanding the dynamics of electrodeposition at solid-solid interfaces. However, the propagation of the interface is often accompanied by a change in density of the metal which is thus, an important order parameter that also affects the stability of electrodeposition at the interface. In the theory of stress-driven phase transformation at solid-solid interfaces studied in geological systems, it has been shown that interfacial stability or roughening condition depends on the density change at the interface[1].
In this work, we will show results on the stability of electrodeposition at the interface between a solid electrolyte and a metal anode for three cases: isotropic-isotropic interface, anisotropic-isotropic interface and both anisotropic interfaces. The anisotropic case is motivated by our recent results on the highly direction dependent moduli of Li metal[2]. In the isotropic case, we show that the condition for stability is sensitive to the mechanical properties[3] (modulus and Poisson’s ratio) and relative partial molar volume of metal in the two phases[4]. We illustrate this using the constructed stability diagram which shows stable regimes of shear modulus and molar volume of metal ion. This stability diagram qualitatively resembles that for stress-driven phase transition at solid-solid interfaces studied by Angheluta et al.[1]. Our analysis shows a new approach of using a soft solid electrolyte provided the density of metal (e.g. Li) is greater in the solid electrolyte than the metal anode. We find that typical inorganic solid electrolytes have higher shear modulus, but lower molar volume than that required for stable electrodeposition while solid polymer electrolytes have higher molar volume but lower shear modulus than the requirement, leading once again to unstable electrodeposition. For the anisotropic case, results show that both high density and low density stable regimes exist, with the critical shear modulus curves shifted depending on the Li surface in contact with the solid electrolyte. Further, we will discuss ways to extend the analysis to other exotic material classes with a different mechanical response like liquid crystals.
[1] L. Angheluta, E. Jettestuen, and J. Mathiesen, Phys. Rev. E 79, 031601 (2009).
[2] C. Xu, Z. Ahmad, A. Aryanfar, V. Viswanathan, and J. R. Greer, Proc. Natl. Acad. Sci. USA 114, 57 (2017).
[3] C. Monroe and J. Newman, J. Electrochem. Soc. 152, A396 (2005).
[4] Z. Ahmad and V. Viswanathan, Phys. Rev. Lett. 119, 056003 (2017).
8:00 PM - ES04.14.36
Surface Impurities on Layered Positive Electrode Materials—Mechanisms for Formation and Impact on Performance
Nicholas Faenza 1 , Lejandro Bruce 1 , Irene Plitz 1 , Nathalie Pereira 1 , Glenn Amatucci 1
1 Materials Science and Engineering, Rutgers, The State University of New Jersey, North Brunswick, New Jersey, United States
Show Abstract
Enhancing the functionality of layered R-3m positive electrode materials for lithium-ion batteries is dependent on a comprehensive understanding of the failure modes prevalent in state of the art batteries. It is well known that layered oxides, such as LiCoO2 (LCO) and LiNi0.8Co0.15Al0.05O2 (NCA), form various surface impurities with exposure to the ambient atmosphere and that these impurities have a detrimental impact on the electrochemical performance of the host material. However, the specific reaction sequences that develop Li2CO3 and other decomposition products remains unclear. A detailed investigation into the relationship between each of the main impurity species and the layered oxide’s electrochemical performance is necessary to elucidate the sources of degradation that builds impedance and reduces the electrode’s functional energy density.
The primary focus of this paper was to answer these critically important questions, and enhance the understanding of how to optimally handle layered oxide materials. Surface sensitive infrared spectroscopy was coupled with thermogravimetric analysis and Karl Fisher coulometry to identify the surface impurities, while extensive electrochemical cycling and impedance spectroscopy measure the impact on the electrode’s performance and impedance. An array of samples, each with a unique combination of atmospheric exposure and thermal treatments enabled the isolation and analysis of individual surface species. Particular attention was given to the electrochemical stability at high states of charge to emphasize the critical role that the surface impurities have on limiting the electrode’s performance.
8:00 PM - ES04.14.38
Organic Monomer as Cathode Material for Li-Secondary Battery
Hui Zhan 1 , Fang Men 1 , Zhiping Song 1
1 College of Chemistry and Molecular Sciences, Wuhan University, Wuhan China
Show Abstract
Organic material, as a rather new member in energy storage family, has attracted much attention and efforts because of its special property in many aspects comparing with other inorganic electrode material. In our recent study, different organic material has been investigated and used for non-aqueous secondary battery.
A series of quinone-based organics were investigated, through which the relation between the molecular structure and the electrochemical property was established. We found the molecular structure greatly influenced the cycling stability of the sample. If with appropriate conformation, even organic monomer could have very stable cycling stability.
In addition, highly conjugated monomer can better utilize the active site. For instance, anion doping and Li+ association/de-association could both contribute capacity and about 300mAh/g capacity could be continuously released. Detailed analysis indicated that the “size” of the monomer also played a big role, as it determined the conjugacy as well as the energy barrier between different LUMO. The subtle relationship could be evidenced by the voltage profile.
In conclusion, organic material with multi-active site was proposed and owing to the synergy, high capacity was achieved, and the dependence of the electrochemical property on the molecular conformation was investigated in detail.
8:00 PM - ES04.14.39
Synthesis of Silicon Anodes via Alloying with Inert Metals for Enhancing Electrochemical Performance of Lithium-Ion Battery
Seongwoo Kwon 1 , Seong-Hyeon Hong 1
1 Materials Science and Engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractSilicon (Si) is an anode material for a lithium ion battery with the highest theoretical capacity, and is attracting an attention as a substitute for commercially available graphite anode material with a low capacity. However, silicon has problems of low lifetime characteristics due to its large volume expansion when inserting lithium ions and low electrical conductivity. Accordingly, there is a need for a design that can provide a buffer layer capable of maintaining the structure during insertion of lithium ions and improve the low electrical conductivity. 3M and Iljin Electric Co. have announced that they can solve the existing problems by forming composite metal alloy with silicon material. In particular, 3M announced that it has acquired a battery with higher capacity in the same volume by using a combination of a conventional graphite anode material and a new silicon alloy anode material.
In this study, a facile sol-gel method of synthesizing silicon anode materials coated with various metal materials was investigated. Before coating metal materials on silicon, micro-sized silicon was etched via a metal-assisted etching method so that porous silicon can be obtained. AgNO3 was selected as oxidant and the effects of the amount of oxidant and etchant were examined during etching process. After the etched silicon particles were aged in the solution containing the metal precursor, the silicon particles and the metal precursor can easily react by drying in a convection oven and heat treatment in a hydrogen atmosphere. These reactions have the advantage of being able to react within a short time and very easy to control the composition. The metal - silicon anode material synthesized in this study can prevent the volume expansion of the silicon anode material by utilizing various metals and metal silicides as a buffer layer, and the electrochemical characteristics can be improved due to the high electrical conductivity of the metal.
As a result, various conditions for metal-assisted etching method were conducted to micro-sized silicon, and the influence of the conditions upon metal alloying process was investigated. Also, the anode materials with an initial efficiency of 85% or higher and a stable lifetime of 100 cycles or more were successfully synthesized.
8:00 PM - ES04.14.40
Polyvinyl Alcohol/Graphene Oxide Electrospun Mat with Improved Electrolyte Performance
Qin Pan 1 , Wei Gao 1
1 , North Carolina State University, Raleigh, North Carolina, United States
Show AbstractHere we describe electrospinning of polyvinyl alcohol (PVA) with graphene oxide (GO) followed by direct laser patterning process, for high-performance monolithic supercapacitors with long-term stability. The PVA-GO electrospun mat infiltrated with 1 M H2SO4 can perform as solid-state electrolyte which maintains a high ionic conductivity of c.a. 2 mS/cm during long-term ambient temperature storage, thanks to the hygroscopic nature of GO and the nanofiber structure. It overcomes the major disadvantage of the conventional PVA-based aqueous gel electrolyte that the performance will decay chronologically due to the significantly increased resistance caused by water evaporation. The PVA-GO nanofibers with large specific surface area and low crystallinity shows improved adsorption of water molecules, which are further bound with GO via hydrogen bonding, leading to excellent moisture retention over time. GO also promotes the ion diffusion in the PVA-GO mat, with its oxygenated groups functioning as proton-hopping sites. The as-prepared monolithic supercapacitor with concentric circular geometry shows a highest areal capacitance of 5.8 mF cm-2, superior to the reported similar EDLC micro-supercapacitors with typical capacitance ranging from 0.5~3 mF cm-2, showing great promise as light-weight and flexible energy storage systems.
8:00 PM - ES04.14.41
Enzymatic Carbon Cycle Inspired Electrochemical Conversion of CO2 – CH4
Younghye Kim 1 , Ki Tae Nam 1
1 , Seoul National University, Seoul Korea (the Republic of)
Show AbstractMost of gaseous carbon on earth exist in the form of CO2 and CH4 which represent 74% of green house gases. As the carbon gas emission has risen since the utilization of carbon fuel, development of conversion pathway from gaseous carbon into value added fuel has emerged as major issue. In this study, concurrent electrochemical conversion of CO2 and CH4 into valuable carbon products was newly demonstrated. The system was inspired from two carbon storage cycle in natural enzymes: Calvin cycle in photosynthesis (CO2 fixation) and catalytic cycle in Methane monooxygenase (CH4 fixation). These cycles do not apply energy/electron directly to CO2 or CH4, but instead, activate them via reactive chemical substrates. Here, we proposed new cycle for concurrent conversion of CO2-CH4 which is distinct from general direct electrochemical conversion. We applied potential ranging from CO2 reduction to CH4 oxidation to utilize the mutual intermediates as active substrate respectively. On the metal electrode, the carbon intermediates absorbed stably until the multi-carbon products were formed during the interactive reaction. After purging the gases to electrolyte, a new oxidation peak was observed followed by CO2 reduction. The oxidation current were highly dependent to the previous reduction step, which indicates successive electrochemical cycle process. In gas chromatography-mass spectroscopy analysis, acetic acid was observed as the main product from the reaction. This is the first report of simultaneous conversion of CO2 and CH4 into multi-carbon products in normal temperature and pressure without additional catalyst. The platform based on the cyclic voltammetry technique is also expected to be applied in other electrochemical catalytic fields including artificial photosynthesis, biomass production and organic synthesis.
8:00 PM - ES04.14.42
Computational Insight into the Li-Ion Insertion Mechanism of VO2(B) Bulk and Surfaces
Shunning Li 1 , Jianbo Liu 1 , Baixin Liu 1
1 School of Materials Science and Engineering, Tsinghua University, Beijing China
Show AbstractInterest in electric vehicles as a solution for environmentally friendly transportation has been stimulated by the recent advances in Li ion battery (LIB) technology. In order to improve the efficiency of electric vehicles, electrode materials that can offer higher capacity at a reduced cost are continuously sought. Bronze-phase vanadium dioxide [VO2(B)], with its unique open framework that not only delivers a theoretical capacity superior to that of LiCoO2 but also facilitates rapid ion diffusion, has been advocated as one of the potential cathode materials for next-generation LIBs. While various forms of VO2(B) nanostructures are experimentally investigated, a comprehensive theoretical understanding of the lithium storage mechanism is still lacking. In the present work, by using density functional theory calculations, we examine the redox mechanism, structural evolution, and the kinetics of Li diffusion in VO2(B). The ground-state Li/vacancy configurations at different discharge stages are determined, from which the calculated voltage profiles are in good agreement with the experimental results in the literature. Energy barrier calculations reveal a pronounced composition dependence of the kinetic diffusion of Li in bulk VO2(B). Moreover, the impact of the surface environment on the Li-ion insertion properties is also demonstrated, which helps explain the different achieved capacity associated with different types of nanoarchitectures for VO2(B). This study may contribute to deeper comprehension and better control of the electrochemical performance of VO2(B) cathodes in LIBs.
8:00 PM - ES04.14.43
The Origin of Capacity Fade of High Ni Layered Cathode Cell and Its Improvement
Meiten Koh 1 , Yoon Sok Kang 1 , Jinah Seo 1 , Insun Park 1 , Dong Yong Kim 1 , Jihyun Jang 1 , Yeonji Chung 1 , Eunah Park 1 , Kimihiko Ito 2 , Yoshimi Kubo 2
1 Material Development Center, Samusung Advanced Institute of Technology, Suwon city Korea (the Republic of), 2 Green, NIMS, Tsukuba-si Japan
Show AbstractLithium-ion battery has been widely employed in electric vehicle applications. Recently there are increasing demands of higher energy density, thus High Ni layered oxides which contains above 80% Ni, are tried to be used as cathode material. Nevertheless, there are several issues that need to be surmounted to use the High Ni layered cathode. Especially, its significant capacity fading at high temperature should be surmounted.
In this study, we have studied high temperature performance of the High Ni layered cathode (LiNi0.8Co0.1Mn0.1O2) cell and its origin of capacity fade, and improved its performance by the electrolyte additive.
We made ca.500mAh 18650 cell by using the High Ni layered cathode (LiNi0.8Co0.1Mn0.1O2), graphite anode, and two kinds of electrolyte. One is the ordinal electrolyte (1.15M LiPF6 EC/EMC/DMC (2/4/4) + VC 1wt%) and the other contained 0.5wt% of the additive to the ordinal electrolyte. Its cycle performance was tested under high temperature and high voltage condition (rate: 1C/1D, temperature: 45C, voltage: 4.3V-2.8V).
Rapid capacity fade with rapid increase of DCIR of the High Ni cathode cell was observed in case of using the ordinal electrolyte. Electrochemical impedance analysis of the cell showed that the rapid increase of DCIR was due to increase of interfacial resistance of both cathode and anode. Chemical analysis of the cell suggested that origin of the increase of interfacial resistance would be elution of transition metal from the cathode. Co rich cubic phase was observed at the surface of primary particle of cathode after cycle, which suggested that Ni at the surface of cathode would be eluted during cycle, thus highly resistant Co rich cubic phase would be generated then increase interfacial resistance of the cathode. ICP analysis showed that a lot of Ni was found on the surface of anode after cycle, which also suggested that Ni at the surface of cathode would be eluted during cycle, and the deposited Ni on the surface of anode would increase interfacial resistance of anode.
Rapid capacity fade with rapid increase of DCIR of the High Ni cathode cell was greatly suppressed by adding 0.5wt% of the additive to electrolyte. Electrochemical impedance analysis of the cell showed that increase of interfacial resistance of both cathode and anode was greatly suppressed. Chemical analysis of the cell suggested that origin of this improving effect would be Ni protection effect of the additive from elution.
8:00 PM - ES04.14.44
Nitrogen-Doped Carbon Coated MoSe2 Microspheres as Advanced Anodes for Enhanced Lithium Storage
Wangjia Tang 1 2 , Xinhui Xia 1 , Jiangping Tu 1
1 Department of Materials Science and Engineering, Zhejiang University, Hangzhou China, 2 , Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Hangzhou China
Show AbstractLithium ion batteries are considered as one of the most promising candidates due to their relatively high energy density, high working voltage and long cycle life. However, graphite, as commercial anode material, has a low theoretical specific capacity of 372 mAh g-1. Recently, transition metal dichalcogenides such as Molybdenum selenide (MoSe2) have attracted increasing interest. In this work, MoSe2 microspheres coated by nitrogen-doped carbon layer has been synthesized by hydrothermal method and thermal polymerization. The MoSe2 microspheres with an average diameter of 200 nm are composed of curved nanoflakes and wrapped by a thin N-C layer with the thickness of 3-5 nm. This designed microsphere structure provides more contact area with electrolyte to increase active sites and make the Li ion insert more easily. Meanwhile, the introduction of N-doped carbon coating can restrain the shuttle effect of polyselenides during the charge-discharge process. The electrochemical performance of the MoSe2/N-C electrode shows a high specific capacity of ∼ 690 mAh g-1 after 100 cycles at a current density of 100 mA g-1; it also exhibits superior rate capacity of 470 mAh g-1 at a high current density of 2000 mA g-1. Additionally, the lithium ion storage mechanism is further investigated by the ex-situ XRD patterns at different cycled states.
8:00 PM - ES04.14.45
Short Pulse Amperometry on Symmetrical Lithium-Solid Polymer Electrolyte Cells
Leonard Blume 1 , Ulrich Sauter 1 , Timo Jacob 2
1 , Robert Bosch GmbH, Stuttgart Germany, 2 Institut für Elektrochemie, Universität Ulm, Ulm Germany
Show AbstractUnderstanding the interface kinetics between Lithium and solid polymer electrolytes (SPE) is crucial for the design of Lithium metal batteries with fast charging capability.
Electrochemical impedance spectroscopy (EIS) [1-3] is typically limited to small signals close to equilibrium. In principle, a non-zero offset current can be applied. In doing so, a concentration gradient is introduced in the electrolyte phase. Thereby, current density and salt concentration at the working electrode are varied at the same time, which is why a detailed model and exact knowledge of the concentration dependent transport properties of the solid electrolyte is required to interpret the data.
To overcome these difficulties, Churikov et al. [4] combined impedance data with short current pulse measurements using symmetrical Lithium cells with several liquid electrolytes.
We present results of a short pulse amperometry technique for a SPE with Lithium electrodes. Millisecond current pulses from 0.1 to 10 mA/cm2 are applied to a symmetrical cell and the voltage response is recorded with submicrosecond time resolution. By variation of e.g. temperature and conductive salt concentration it is possible to determine interfacial kinetics for a wide range of current densities. The experimental current-voltage characteristics are compared to a 1D electrochemical continuum model.
[1] A. Teyssot et al., Solid State Ionics 177 (2006), 141-143
[2] A. Bac et al., J. Power Sources 159 (2006), 438-442
[3] S. Liu et al., J. Power Sources 196 (2011), 7681-7686
[4] A.V. Churikov, I.M.Gamayunova and A.V. Shirokov, J. Solid State Electrochem 4 (2000), 216-224
8:00 PM - ES04.14.46
All-Nanomat Li-Ion Batteries—A New Cell Architecture Platform for Ultrahigh Energy Density and Mechanical Flexibility
Ju-Myung Kim 1 , Sang-Young Lee 1
1 , UNIST, Ulsan Korea (the Republic of)
Show AbstractThe on-going surge in demand for high-energy/flexible rechargeable batteries relentlessly drives technological innovations in cell architecture as well as electrochemically active materials. Here, we demonstrate a new class of all-nanomat lithium-ion batteries (LIBs) based on one-dimensional (1D) building elements-interweaved heteronanomat skeletons. Among various electrode materials, silicon (Si, for anode) and over-lithiated layered oxide (OLO, for cathode) materials are chosen as model systems to explore feasibility of this new cell architecture and achieve unprecedented cell capacity. Nanomat electrodes, which are completely different from conventional slurry-cast electrodes, are fabricated through concurrent electrospinning (for polymeric nanofibers) and electrospraying (for electrode materials/carbon nanotubes (CNTs)). Si (or rambutan-shaped OLO/CNT composite) powders are compactly embedded in the spatially interweaved polymeric nanofiber/CNT heteromat skeletons that play a crucial role in constructing three-dimensional (3D)-bicontinuous ion/electron transport pathways and allow for removal of metallic foil current collectors. The nanomat Si anodes and nanomat OLO cathodes are assembled with nanomat Al2O3 separators, leading to the fabrication of all-nanomat LIB full cells. Driven by the aforementioned structural/chemical uniqueness, the all-nanomat full cell shows exceptional improvement in electrochemical performance (notably, cell weight-based energy density = 479 Wh kgCell-1) and also mechanical deformability, which lie far beyond those achievable with conventional LIB technologies.
8:00 PM - ES04.14.47
Revealing the Electrochemical Charging Mechanism of Nano-Sized Li2S by In Situ and Operando X-Ray Absorption Spectroscopy
Liang Zhang 1 , Jinghua Guo 1
1 Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California, United States
Show AbstractLithium sulfide (Li2S) is a promising cathode material for Li/S cells due to its high theoretical specific capacity (1166 mAh g-1) and capability to pair with non-metallic lithium anodes to avoid potential safety issues.1,2,3,4,5 However, when used as the cathode a high charging voltage (~ 4 V vs. Li+/Li) is always necessary to activate Li2S in the first charge process, and the voltage profile becomes similar to that of a common sulfur electrode in the following charge processes.
In this presentation, I will show the investigation of the charging mechanism of an electrode composed of nano-sphere Li2S particles in real time throughout the initial two charge processes by in-situ and operando X-ray absorption spectroscopy. The results indicate that Li2S is directly converted to sulfur through a two-phase transformation in the first charge process while it is oxidized first to polysulfides and then to sulfur in the second charge process. The origin of the different charging mechanisms and thus different charge voltage profiles of the first and following charge processes is found to be related to the remaining polysulfides at the end of first discharge process: they can not only facilitate the charge transfer process at the Li2S/electrolyte interface but also chemically react with Li2S and act as the polysulfide facilitator for the electrochemical oxidation of Li2S in the following charge processes. Our present study provides a new fundamental understanding of the charging mechanism of the Li2S electrode, which should be of help for the further development of high-performance Li/S cells.
References:
1. Yang et al., J. Am. Chem. Soc., 2012, 134, 15387.
2. Sun et al., Nano Energy, 2016, 26, 524
3. Hwa et al., Nano Lett., 2015, 15, 3479.
4. Ye et al., J. Phys. Chem. C, 2016, 120, 10111.
5. Feng et al., Phys. Chem. Chem. Phys., 2014, 16, 16931.
8:00 PM - ES04.14.48
Revealing Nanoscale Passivation and Corrosion Mechanisms of Reactive Battery Materials in Gas Environments
Yuzhang Li 1 , Yanbin Li 1 , Yi Cui 1
1 , Stanford University, Stanford, California, United States
Show AbstractLithium (Li) metal is a high-capacity anode material (3,860 mAh g-1) that can enable battery chemistries beyond Li-ion. However, Li metal is highly reactive and repeatedly consumed when exposed to liquid electrolyte (during battery operation) or the ambient environment (throughout battery manufacturing). Studying these corrosion reactions on the nanoscale is especially difficult due to the high chemical reactivity of both Li metal and its surface corrosion films. Here, we directly generate pure Li metal inside an environmental transmission electron microscope (TEM), revealing the nanoscale passivation and corrosion process of Li metal in oxygen (O2), nitrogen (N2), and water vapor (H2O). We find that while dry O2 and N2 (99.9999 vol%) form uniform passivation layers on Li, trace water vapor (~1 vol%) disrupts this passivation and forms a porous film on Li metal that allows gas to penetrate and continuously react with Li. To exploit the self-passivating behavior of Li in dry conditions, we introduce a simple dry-N2 pretreatment of Li metal to form a protective layer of Li nitride prior to battery assembly. The fast ionic conductivity and stable interface of Li nitride results in improved battery performance with dendrite-free cycling and low voltage hysteresis. Our work reveals the detailed process of Li metal passivation/corrosion and demonstrates how this mechanistic insight can guide engineering solutions for Li metal batteries.
One Sentence Summary: Using operando TEM, we gain a detailed understanding of the nanoscale passivation and corrosion mechanisms of the reactive Li metal, which guides our design of a protective Li nitride layer for stable Li metal batteries.
8:00 PM - ES04.14.49
Synthesis of 3D Urchin-Like NiCo2O4 as an Excellent Rate Capability Electrode Material for Supercapacitors
Jijun Zhang 1 , Zexiang Chen 1 , Yan Wang 1 , Hai Li 1
1 School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu, SiChuan, China
Show AbstractDevelopment of a practical and effective energy storage technologies to ensure a safe, reliable and efficient energy supply for the future is exceptional urgent. As a very promising energy storage technology, supercapacitors have attracted widely attention due to their rapid charging and discharging, high power density, and long cycle life. As we know that the performance of supercapacitors depends primarily on the properties of the electrode materials. The internal properties of electrodes determine the energy density of the material.
Here, we report a fabrication of 3D urchin-like NiCo2O4 nanostructures by a simple and practical hydrothermal method and then followed by an annealing process for energy storage application. The sodium-p-styrenesulfonate (PSS) played an important role in forming the urchin-like nanostructure. The formation of the 3D urchin-like NiCo2O4 nanostructure was showed by the scanning electron microscope (SEM). The cyclic voltammetry (CV) measurements were performed using a three-electrode system in a 6 M KOH electrolyte. The CV curves exhibited a similar shape at all scan rates, revealing typical pseudocapacitive characteristics and excellent rate capability. The as-prepared NiCo2O4 electrode exhibited a high specific capacitance of 742 F/g (22.26 F/cm2) at a current density of 1 A/g (30 mA/cm2) and an excellent rate capability of 608 F/g (18.24 F/cm2) at 50 A/g (1500 mA/cm2). The as-prepared 3D urchin-like NiCo2O4 presents following features: The unique structure of this NiCo2O4 effectively prevents the aggregation of NiCo2O4 which nanomaterials often happened, greatly increases the electrolyte in contact with the active material, and hence provides much more the activity area for fast Faradaic redox reactions. The electrons can be transmitted through the rod-shaped NiCo2O4 in the urchin-like NiCo2O4 which presents highly efficient electron transport pathway, leading to lower charge-transfer resistance and better rate capability. And also the structure can efficiently buffer the volume change of the electrode material during redox reaction caused by the OH-ion insertion/extraction process, resulting in good cycling performance. Additionally, this method proposed in the paper can also be used to fabricate Nickel cobalt oxide based nanostructures with different morphologies by simply controlling the addition of PSS during synthesis.
8:00 PM - ES04.14.50
Functional Two-Dimensional Coordination Polymeric Layer as a Charge Barrier for Li-S Battery Application
Jing-Kai Huang 1 , Mengliu Li 1 , Yi Wan 1 , Lain-Jong Li 1
1 Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal Saudi Arabia
Show AbstractTwo-dimensional (2D) polymeric layers have attracted intensive research efforts owing to their unique physical properties which make them especially interesting for separation technologies. Separating gases and molecules are based on the commonly accepted size exclusion mechanism. However, the separation or applications based on charge exclusion principle is still rare. Here, we demonstrate a simple, room-temperature and large-area synthesis of nanometer-thin Zn2+-Benzimidazolate free-standing 2D coordination polymers at the air/water interfaces, where the hydroxyl groups are stoichiometrically coordinated into the 2D structures and implement electrostatic charges in the 2D structures. We show that our 2D Zn coordination polymer layers serve as charge barrier to the transport of negative sulfur ions resulting in efficiently mitigate the S-shuttle effects in Li-S battery and largely promote the battery capacity and cycle performance.
8:00 PM - ES04.14.51
Antimony Doped Tin Oxide (ATO)—Synthesis, Characterization and Application as Cathode Material in Li-O2 Cells—Implications on the Prospect of Carbon-Free Cathodes for Rechargeable Lithium-Air Batteries
Hans Beyer 1 , Michael Metzger 1 , Johannes Sicklinger 1 , Xiaohan Wu 1 , K. Uta Schwenke 1 , Hubert Gasteiger 1
1 , Technical University of Munich, Garching Germany
Show AbstractLi-air batteries have attracted huge interest due to their outstanding theoretical energy density. Although the practical advantages over Li-ion technologies are yet uncertain, an improved understanding of Li-O2 electrochemistry at the interface between cathode and electrolyte contributes to expanding the frontiers of electrochemistry and materials science.
The cycle life of aprotic Li-O2 cells depends on the reversible formation/decomposition of Li2O2 on the cathode surface via a 2 e- reaction. Though the formation of Li2O in a 4 e- process could enable higher capacities, it has previously not been evidenced to a substantial amount. The major hindrance of a reversible Li-O2 cell chemistry are parasitic side reactions triggered by superoxide radicals formed during discharge [1] and singlet oxygen produced during charge [2], causing the oxidation of state of the art carbon cathodes and glyme electrolytes [3]. The prevailing product Li2CO3 accumulates on the cathode surface during cycling and ultimately leads to cell failure [4]. The need for novel carbon-free cathode materials is thus evident.
Herein, we present the hydrothermal synthesis of highly conductive crystalline ATO nanoparticles, the fabrication of ATO electrodes with high surface area, and their application as cathodes in Li-O2 cells [5]. We use a pressure transducer and an online electrochemical mass spectrometer to quantify consumed and evolved gases during discharge and charge of Li-O2 cells. Solid discharge products on ATO cathodes are identified by infrared spectroscopy and quantified by acid-base titration and UV-vis spectroscopy. Thus we demonstrate an unprecedented cell chemistry: In contrast to carbon cathodes, ATO cathodes enable the formation of substantial amounts of Li2O and prevent the formation of Li2CO3 on the cathode surface. Formed Li2O can be recharged at high potentials, which leads to the evolution of oxygen. This finding is remarkable, because according to our previous study with Li2O-prefilled carbon cathodes, Li2O would not be rechargeable at all on a carbon support without catalyst [6]. These new mechanistic insights provide implications for cathode design concepts that might enable the reversible cycling of Li-O2 cells.
[1] K. U. Schwenke, S. Meini, X. Wu, H. A. Gasteiger, M. Piana, Phys. Chem. Chem. Phys. 15, 11830 (2013).
[2] J. Wandt, P. Jakes, J. Granwehr, H. A. Gasteiger, R.-A. Eichel, Angew. Chem. 128, 7006 (2016).
[3] H. Beyer, S. Meini, N. Tsiouvaras, M. Piana, H. A. Gasteiger, Phys. Chem. Chem. Phys. 15, 11025 (2013).
[4] S. Meini, M. Piana, H. Beyer, J. Schwämmlein, H.A. Gasteiger, J. Electrochem. Soc. 159, A2135 (2012).
[5] H. Beyer, M. Metzger, J. Sicklinger, X. Wu, K. U. Schwenke, H. A. Gasteiger, J. Electrochem. Soc. 164, A1026 (2017).
[6] S. Meini, N. Tsiouvaras, K. U. Schwenke, M. Piana, H. Beyer, L. Lange, H. A. Gasteiger, Phys. Chem. Chem. Phys. 15, 11478 (2013).
8:00 PM - ES04.14.52
Phosphorous Doped (P) Nanoporous Carbons Derived from Lignocellosic Biomass for Sodium-Ion Capacitor with Organic Electrolytes
Sul Ki Park 1 , Ho Seok Park 1
1 , Sungkyunkwan University, Suwon Korea (the Republic of)
Show AbstractNowadays, electrical double layer capacitors (EDLCs) have been attractive energy storage devices due to high power density and long cycle stability. But, energy density of EDLCs using carbon electrode is limited to below 10 W h kg-1. Energy density can be enhanced by increasing the capacitance and voltage window. Nanoporous carbon nanomaterials with high surface area and stability have been used as an attempt to improve capacitance. In addition, heteroatom-incorporated carbons can enhance capacitance by surface redox reactions with ion. Using an organic electrolyte can increase energy density due to wider potential window than aqueous electrolytes. In specially, sodium system based organic electrolyte are a highly promising alternative to the lithium ion electrical devices with high energy density due to high abundant and environmentally benign features than lithium.
In this study, we report a high-performance sodium ion energy storage based organic electroltye using novel phosphorous (P) doped nanoporous carbon via a one-step hydrothermal method. The doped nanoporous carbons have highly active sites and well-developed pores with the high surface area and pore volume of 1109 m2 g-1 and 0.630 cm3 g-1, respectively, 330 times greater than those of raw lignocellosic biomass. In particular, P doped porous carbons exhibited the high specific capacitance of 233.81 F g-1 at 2 m V-1 and stable cycle retention after 5000 cycles in 1M NaClO4 in EC/DMC. Consequently, this chemical synthesis can be an important opportunity for the transformation of raw biomass to valuable materials.
8:00 PM - ES04.14.53
Computational Material Design of New Li-Rich Layered-Oxide Electrode Materials
Soo Kim 1 , Muratahan Aykol 2 , Vinay Hegde 1 , Zhi Lu 1 , Scott Kirklin 1 , Jason Croy 3 , Michael Thackeray 3 , Christopher Wolverton 1
1 , Northwestern University, Evanston, Illinois, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 , Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractDesigning new cathode materials for lithium-ion batteries that can provide higher cell energy densities for emerging applications such as electric vehicles and energy storage system has received significant attention recently. Several cathode materials, such as Li2MnO3-stabilized LiMO2 (M = Mn/Ni/Co),1 Li2Ru0.75Sn0.25O3,2 and disordered Li2MoO3-LiCrO2 compounds3 can yield a very high discharge capacity of >200 mAh g-1. This hints at the constructive role of Li-rich Li2MO3 (M4+) compounds in these systems, either acting as active cathodes or inactive stabilizers. For instance, in xLi2MnO3-(1-x)LiMO2 cathodes, Li2MnO3 serves as a stabilizing agent when charged below 4.4 V vs. Li/Li+, or as an excess lithium reservoir above 4.4 V.1 While utilizing a Li2MO3-type structure alone as an active cathode has received little attention until recently,2-5 it was discovered that Li2Ru0.75Sn0.25O3 can yield superior voltage and capacity retention, in which Li2SnO3 serves as a stabilizer.2 Recent studies have suggested that the (de-)lithiation reactions of Li2IrO3, Li2Ru1-xIrxO3, and Li2Ir0.75Sn0.25O3 cathodes undergo both cationic and anionic redox processes.2,4-5
Design of such Li-rich, high-capacity layered oxides requires a knowledge, not only understanding their thermodynamic stability at various states of charge, but also assessing structural instabilities during charge/discharge cycling runs, for example, metal migration and oxygen release tendencies. One of the most powerful tools to perform such a systematic survey is high-throughput density functional theory within a large materials database, such as the Open Quantum Materials Database consisting of >450,000 compounds from the Inorganic Crystal Structure Database and decorations of commonly occurring crystal structures.6 We will propose a list of Li-rich, high-capacity cathode materials that can achieve structural stability at high voltages, favorable metal mixing, coherent interfaces, and high energy cell density. In particular, our studies predict several new candidates with a higher energy density than Li2Ru1-xSnxO3 and Li2Ir1-xSnxO3;2,5 and help elucidate trends and directions for designing high-energy layered oxide cathodes.
This work was supported by Northwestern-Argonne Institution of Science and Engineering and the Dow Chemical Company. Also, this work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design, and it was supported as part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (Award No. DE-AC02-06CH11357).
[1] J. Mater. Chem. 17, 3112 (2007)
[2] Nat. Mater. 12, 827(2013)
[3] Science 343, 519 (2014)
[4] J. Electrochem. Soc. 161, A934 (2014)
[5] Science 350, 1516 (2015)
[6] npj Computational Materials 1, 15010 (2015)
Symposium Organizers
Cengiz Ozkan, University of California, Riverside
Ali Coskun, Korea Advanced Institute of Science and Technology
Ekaterina Pomerantseva, Drexel University
Federico Rosei, Université du Quebec
ES04.15: Other Battery Materials III
Session Chairs
Zhongwei Chen
Xueliang Sun
Thursday AM, November 30, 2017
Hynes, Level 3, Ballroom A
8:00 AM - *ES04.15.01
Engineering Interfaces in Large Format Batteries for Grid Energy Storage
Babu Chalamala 1 , Erik Spoerke 1 , Leo Small 1 , Timothy Lambert 1 , Jonathon Duay 1 , Travis Anderson 1
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractEnergy storage is a critical enabler for the modernization of the electricity grid and for the large-scale integration of distributed energy resources into the grid infrastructure. The research program at Sandia National Laboratories includes the development low cost battery technologies, power electronics and power conversion systems, safety of grid energy storage systems, and controls and architectures for optimum utilization of energy storage systems. In battery technologies, our research focus is on the development of lower temperature Sodium-based batteries, rechargeable alkaline batteries, and membranes and electrolyte materials flow batteries with improved cycle life and system cost. These technologies are well suited for large format cells and offer opportunities for lower cost when manufactured at scale. However, realizing the full potential of these systems requires optimizing the chemical, electronic, and ionic behavior across the numerous interfaces in these systems. In this paper, we will discuss recent work in engineering large format cells and discuss the role of interactions at the electrode interfaces on the performance, cycle life and safety of these batteries.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
8:30 AM - ES04.15.02
Lithium-Iron (III) Fluoride Battery with In Situ Surface Protection
Enbo Zhao 1 , Xiaosi Gao 1 , Danni Lei 2 , Yiran Xiao 1 , Xiaolei Ren 1 , Wenbin Fu 1 , Chenchen Hu 1 , Xiaobo Zhang 1 , Qiao Huang 1 , Alexandre Magasinski 1 , Seth Marder 1 , Gleb Yushin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 , Tsinghua University, Shenzhen China
Show AbstractLithium (Li) – ion batteries utilizing conventional intercalation electrodes approach their theoretical limits and further improvements in their energy storage characteristics are limited.[1] Recently, Li-metal fluoride (MF) batteries based on conversion chemistry are attracting intensive research efforts owing to their high energy density, exceeding that of the Li-sulfur (S) cells.[2] FeF3 is considered one of the most attractive due to the low cost and toxicity, abundance of Fe, the highest specific capacity of 712 mA h g-1 and high average potential of ~2.74 V, offering an exceptionally high cell-level theoretical energy density in excess of 1500 W h L-1 (on a repeat unit basis) and cell-level specific energy in excess of 800 W h kg-1 (also on a repeat unit basis).[2]
Unfortunately, commercialization of FeF3 is still prevented by multiple limitations. One major drawback is the notoriously poor electronic conductivity of fluorides, resulting from the large band gap induced by strong ionicity of Fe-F bond. Another drawback is the rapid degradation during cycling, induced by the significant volume change during the conversion reaction and the consequent mechanical failures, as well as the dissolution of FeF3 triggered by free protons produced from undesired electrolyte decomposition or oxidation. In order to address these two challenges, recent endeavors have been devoted to the design of various nanostructures, including high-energy ball milling with conductive additives, HF-based aqueous solution synthesis and ionic liquid assisted synthesis, etc., regardless of the hazardousness and high cost. But in spite of these efforts, the majority of previous works still showed limited capacity and fast decay in less than 50 cycles.
In this research, we report a holistic strategy to overcome the above limitations and improve the electrochemical performances of Li-FeF3 cells by a novel design of the FeF3 nanostructure, combined with protective shells surrounding the composite particles and careful electrolyte optimization. The rational architecture of uniform FeF3-CNT nanocomposites provides enhanced electronic conductivity and effectively accommodates the volume expansion during lithiation. This simple approach is applicable for the synthesis of a broad range of MFs and does not require the use of hazardous starting materials, such as HF. The use of uniform coatings produced by atomic layer deposition (ALD) in combination with the solid electrolyte interphase (SEI) induced by customized electrolyte compositions prevent the active material from undesirable direct contact with liquid electrolyte. As a result, Li-FeF3 cells show capacity retention of over 90% after 300 cycles. When compared with previously published work on FeF3, our as-fabricated cells improve electrochemical stability for up to 10 times.
[1] N. Nitta, F. Wu, J. T. Lee, G. Yushin, Mater. Today, 2015, 18, 252-264.
[2] F. Wu, G. Yushin, Energy Environ. Sci., 2017, 10, 435-459.
8:45 AM - ES04.15.03
High-Power, Low-Corrosion Aluminum-Air Battery
Brandon Hopkins 1 , Douglas Hart 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractAluminum-air (Al-air) batteries are promising candidates for use in electric vehicles due to their high pack-level energy densities and to the abundance, recyclability, lightweight, low cost, and three-electron redox properties of aluminum. Severe self-discharge during open-circuit conditions, however, has limited Al-air commercialization for over 50 years. Such self-discharge is induced by corrosion wherein the aluminum anode reacts with water in the battery’s aqueous electrolyte without performing useful work. Existing open-circuit corrosion mitigation methods described in the literature can stop open-circuit corrosion but only in exchange for low power densities (91.1 mW/cm2) and specific energies (1.2 kWh/kg-Al). Here we present a high-power (472 mW/cm2), energy-dense (4.0 kWh/kg-Al) Al-air battery that experiences no long-term open-circuit corrosion. Long-term open-circuit corrosion can be stopped by pumping in a non-conducting liquid oil to displace the corrosive electrolyte during open-circuit conditions. Under closed-circuit conditions, the electrolyte is pumped back in to displace the oil. We provide analytical analysis and supporting empirical images to describe the fundamental mechanisms associated with displacing the oil from the anode and cathode surfaces via flowing electrolyte and conversely with displacing electrolyte with oil. Under a range of achievable conditions, we experimentally demonstrate that the oil does not foul the anode and cathode surfaces resulting in no observable decrease in discharge performance. We hypothesize that a lack of familiarity with underwater oleophobicity in the context of batteries maybe a key reason for why this solution to open-circuit corrosion has not been pursued in the published literature for over 5 decades. We estimate that a mechanically rechargeable Al-air vehicle battery pack with the proposed corrosion mitigation system could achieve energy densities of 222 Wh/kg (2x that of Li-ion vehicle packs) and 183 Wh/L (comparable to Li-ion vehicle packs) at costs as low as 18 US$/kWh (11x less than Li-ion packs). We anticipate that our findings will further enable the use of aluminum as a critical, alternative element for energy storage.
9:00 AM - ES04.15.04
Selenium-Impregnated Porous Co and N- Co-Doped Carbon as Superior Cathode for Li-Se Batteries
Weiqiang Lv 1 , Weidong He 1 , Jiangwei Li 1
1 School of Energy Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
Show AbstractThree-dimensional, porous graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) is prepared with metal-organic framework (MOF) and employed as Lewis base matrix to host selenium. Owing to the unique structure with abundant micro/meso-pores, the highly conductive C-Co-N matrix provides highly efficient channels for electron transfer and ionic diffusion, and sufficient surface area for loading of selenium nanoparticles while mitigating dissolution of polyselenides and suppressing volume expansion. The homogenous distribution of cobalt nanoparticles and nitrogen-group in C-Co-N composite not only immobilizes polyselenides through strong chemical interaction, but also enhances the catalytic effects in the operation of Li-Se batteries. With a very high Se loading of 76.5 wt%, the C-Co-N/Se cathode delivers superior electrochemical performance with an ultrahigh reversible capacity of 672.3 mAh g-1 (99.6% of the theoretical value) and a capacity of 574.2 mAh g-1 after 200 cycles, giving a capacity fading of only 0.07% per cycle and a nearly 100% Columbic efficiency. In-situ Raman spectroscopy and density functional theory simulations are employed to investigate the Se (de)lithiation mechanism at the electrolyte/cathode interface, and confirm that the structure and composition of C-Co-N scaffold give rise to efficient cathode host for high-performance Se-based cathodes with dramatically reduced capacity fading.
9:30 AM - ES04.15.06
Sodium Metal Sulfate Alluaudite Class of High Voltage Battery Insertion Materials
Debasmita Dwibedi 1 , Prabeer Barpanda 1
1 , Indian Institute of Science, Bangalore India
Show AbstractBatteries are constantly being developed to propel an increasingly diverse range of applications, which can be broadly divided into two categories: volume/weight-restricted applications like electronics/ automobiles and volume/weight independent uses such as grid storage systems. While the Li-ion batteries are indispensable for the former category, the later category can be economically catered by the potential price alternative Na-ion batteries. It has led to the intensive exploration of a wide range of cathode materials. In this quest, suites of polyanionic compounds have been discovered as they provide robust open framework structure facilitating Na+ migration along with chemical/ thermal stability. Among various polyanionic systems [(XO4)m: X = B, P, V, S, Si, Ti etc.], sulfate based compounds delivers the highest redox potential due to their strong electron withdrawing nature. A recent report on a polymorph of NASICON type Na2Fe2(SO4)3 adopting an alluaudite type mineral structure has marked the highest ever Fe3+/Fe2+ redox potential (ca. 3.8 V vs. Na+/Na0) (Barpanda et al., Nature Comm., 5:4358, 2014). It has opened up ‘alluaudite’ family of insertion materials [Na2+2xM2-x(SO4)3] to design efficient sodium cathodes.
Dwelling on the ‘synthesis–structure–electrochemistry’ of these alluaudite compounds, this work attempts to replace the reported cumbersome synthesis with energy-miser solvothermal routes. Synthesis of SO4-based compounds is tricky due to their tendency towards thermal decomposition and water dissolution. In the first report, solid-state synthesis was employed with annealing at 350 °C for 24 h. Aware of the fact that diffusion in liquid is much faster than solids, we have pursued ionothermal synthesis leading to phase pure product with tunable size/ morphology and desirable electrochemistry involving lower annealing temperature of 300 °C (Dwibedi et al., ACS Appl. Mater. Interfaces, 8, 6982, 2016). With the success of this non-aqueous route, we then proceeded towards aqueous solvotherml routes. Using two-step spray drying and Pechini methods, we have succeeded in preparing pristine alluaudite sulfate while registering the lowest annealing temperature (ca. 200 °C) and/ or the shortest annealing duration (ca. 6 h). While pursuing these solvothermal synthesis, we also marked that a range of off-stoichiometry led to same structure, which is interesting from structural and redox mechanism point of view. Using these synthesis protocols, we have discovered two potential high-voltage alluaudite analogues: namely a 5 V Na2.32Co1.84(SO4)3 (Dwibedi et al, Dalton Trans., 46, 55, 2017) and a 4.4 V Na2.44Mn1.79(SO4)3 (Dwibedi et al, J. Mater. Chem. A, 3, 18564, 2015). We have explored the structural and electrochemical performance of (Fe-Mn, Fe-Co, Fe-Ni) solid-solutions alluaudites. We will describe the synthesis, structural and electrochemical aspects of these SO4-based alluaudites and compare them with the PO4-based alluaudite cathodes.
9:45 AM - ES04.15.07
Reaction Mechanism of Rechargeable Magnesium-Sulfur Battery
Daisuke Mori 1 2 , Ryuhei Matsumoto 1 2 , Kiyoshi Kumagae 1 2 , Yoshifumi Mizuno 1 2 , Shizuka Hosoi 1 2 , Kazuhiro Kamiguchi 1 2 , Naoki Koshitani 1 2 , Yuta Inaba 1 , Yoshihiro Kudo 1 , Hideki Kawasaki 3 , Elizabeth Miller 4 , Johanna Weker 4 , Michael Toney 4 , Yuri Nakayama 1 2
1 , Sony Corporation, Kanagawa Japan, 2 , Murata Manufacturing Co., Kyoto Japan, 3 , KRI, Inc., Kyoto Japan, 4 , SLAC National Accelarator Laboratory, Menlo Park, California, United States
Show AbstractMagnesium (Mg) is an attractive candidate for the anode material of a high-performance next generation battery because of its high energy density, moderate electrochemical activity, and natural abundance. In particular, the magnesium-sulfur battery, composed of a Mg anode and sulfur (S) cathode, is a novel rechargeable battery system that can potentially achieve larger energy densities than the theoretical limit of lithium ion batteries (LIB), whose material costs could be reduced down to one-third of that of LIB. Here we report the reaction mechanism of the Mg-S rechargeable battery revealed by X-ray photoelectron spectroscopy, X-ray diffraction, X-ray absorption fine structure, and transmission X-ray microscope measurements. From the results of both ex-situ and in-operando analysis, it has been found that the S cathode shows irreversible morphological changes in the initial discharge, while it shows electrochemically reversible performance in the subsequent charge and discharge reaction of the Mg-S battery. Analyses in detail, suggested reaction mechanism, challenges and prospects of Mg-S battery will be discussed in this presentation.
ES04.16: Electrode Materials II
Session Chairs
Babu Chalamala
Ekaterina Pomerantseva
Thursday PM, November 30, 2017
Hynes, Level 3, Ballroom A
10:30 AM - *ES04.16.01
Roles of Solid Electrolyte Interphases in Conversion-Type Cathodes for Rechargeable Lithium Batteries
Gleb Yushin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractCoversion-type high capacity cathode materials for rechargeable Li metal and Li-ion batteries offer promisses for higher specific energy and reduced battery costs. This overview talk will first discuss cost, volumetric and specific capacities, energy densities, volume changes and rate performance of group 6 and group 7 - based materials, such as sulphur (S) & lithium sulphide (Li2S), selenium (Se) & lithium selenide (Li2Se), tellurium (Te) & lithium telluride (Li2Te), metal fluorides, metal chlorides, metal bromides and metal iodides. Issues, such as volume changes, cathode dissolution, low electronic and ionic conductivities, voltage hysteresis, self-discharge and irreversible structural changes as well as possible routes to mitigate those issues will be discussed. Emphasis will be given to Li-S/Li2S as well as Li-metal fluoride chemistries. The impacts of the solid electrolyte interphase (SEI) layers (forming on the anode and the cathode) on the stability and rate performance of these cells will be elucidated. Challenges in the implementation of these chemistries will be compared with the potential of some of the chemistries to increase the energy density and specific energy of Li and Li-ion batteries.
11:00 AM - ES04.16.02
Thermal, Mechanical and Electrochemical-Induced Structural Changes in Li-Ion Storage Electrodes
George Demopoulos 1
1 , McGill University, Montreal, Quebec, Canada
Show AbstractTwenty-five years after the commercialization of the first Li-ion battery (LIB) that made possible the ubiquitous proliferation of all types of mobile devices, we are entering the exciting era of LIB-powered transportation. In this context, electrode materials characterized by low cost, safety and high reversible specific capacity enabling long range driving and LIB lifespan are among industry’s priorities. Nanostructured electrode materials are at the forefront of many of the new generation LIB developments as are characterized typically by higher Li-ion storage capacities and charging/discharging rates. However, nanostructuring may lead in many instances to significant capacity loss/fade and structure instability with extended cycling. For developing superior performing Li-ion batteries, it is critical that we understand the structural changes the electrode materials experience at the nanoscale upon repeated cycling (intercalation/deintercalation). It is the purpose of this communication to report on our recent studies that have focused on two nanostructured materials of interest, the high-capacity lithium iron orthosilicate (Li2FeSiO4) cathode1 and the high-rate Li4Ti5O12 spinel anode2. In particular, we plan to discuss: (a) thermally (during annealing-synthesis) and electrochemically (during cycling) originated structural relaxation occurring in lithium titanate nanosheet anodes that leads to capacity fade; and (b) phase changes and alteration of Li-ion storage behavior occurring in lithium iron silicates during their charging/discharging following annealing or planetary milling. These comparative material studies provide new insight into critical synthesis, nanostructure, and electrochemical parameters affecting Li-ion electrode energy storage performance that can have significant implications in the development of new generation LIB materials.
Acknowledgments: This work is supported through a Hydro-Québec/NSERC Canada CRD research grant.
References: 1. Xia Lu et al., J. Power Sources, 329 (2016) 355-363; Xia Lu, et al., Scientific Reports, 2015, 5, 8599. 2. Hsien-Chieh Chiu et al., Nano Energy, DOI 10.1016/j.nanoen.2016.12.063; Hsien-Chieh Chiu et al., Adv. Energy Mat. DOI 10.1002/aenm.201601825.
11:15 AM - ES04.16.03
Creating Heterointerface in Layered Oxides for Battery Electrodes
Mallory Clites 1 , Varun Natu 1 , Ekaterina Pomerantseva 1
1 , Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractLayered transition metal oxides show high redox activity and high operation voltages prompting their use as cathodes in intercalation-based electrochemical energy storage systems. However, low electronic conductivity of oxides limits their performance. This issue can be potentially resolved through creating a material with an oxide/carbon heterointerface, where a conductive carbon layer and an oxide layer alternate [1]. In this work, we will present a heterostructure synthesis approach based on a sol-gel process that has the distinct advantage of producing solid oxides from chemically homogeneous solutions [2]. Due to the atomic-level mixing, sol-gel chemistry offers great control over material composition and structure. The sol-gel process occurs through the formation of a liquid precursor followed by the oxide growth in a sequence of hydroxylation and condensation reactions. In the first strategy, solid particles of a conductive material, such as flakes of graphene or graphene oxide, are added into the mixture at solution stage allowing for the growth of oxide on the surface of a carbon flake. In the second strategy, organic molecules added into solution are trapped between the layers of forming oxide followed by hydrothermal treatment leading to carbonization of organics. We will present our results on utilization of both strategies using vanadium oxide as high performing electrode material. We will discuss challenges and solutions for the formation of the heterointerface and report electrochemical performance of the synthesized heterostructures in intercalation-based electrochemical energy storage systems.
1. E. Pomerantseva & Y. Gogotsi, Two-dimensional heterostructures for energy storage, Nature Energy 2 (2017) 17089.
2. M. Clites, B. Byles & E. Pomerantseva, Effect of aging and hydrothermal treatment on electrochemical performance of chemically pre-intercalated Na-V-O nanowires for Na-ion batteries, J. Mater. Chem. A 4 (2016) 7754.
11:30 AM - ES04.16.04
Long Term Cycling Stability of SnO2-Graphite Electrodes
Yuri Surace 1 , Tiphanie Schott 1 , Patrick Lanz 2 , Simone Zuercher 2 , Michael Spahr 2 , Petr Novák 1 , Sigita Urbonaite-Trabesinger 1
1 , Paul Scherrer Institut, Villigen PSI Switzerland, 2 , Imerys Graphite & Carbon, Bodio Switzerland
Show AbstractLi-ion rechargeable batteries are the dominant power sources for portable electronics. However, batteries with higher specific energy and power than current on the market (ca.200 Wh/kg) are needed to satisfy the energy demand of emerging applications such as electric vehicles and stationary storage. The specific energy of a Li-ion battery can be increased by either developing cathodes with higher voltage and/or by developing anodes and cathodes with higher specific charge. It can be easily shown by using an energy-cost model developed by our group that coupling an anode with a specific charge of 500 mAh/g with a LR-NMC cathode results in an increase of the specific energy of the full-cell up to 15% (Berg et al. 2015). A fast and easy approach to reach such anode performance is by adding defined amounts of specific-charge-enhancing compounds (e.g. SnO2) to a graphite-based electrode.
Tin oxide (SnO2) has been investigated in the last few years as one of the most promising metal oxide anode materials for Li-ion batteries due to its high theoretical specific charge (1494 mAh/g). The lithium storage capacity of SnO2 is the result of conversion and alloying reactions (Courtney and Dahn 1997). During the 1st lithiation, SnO2 reacts with lithium and is converted to Sn nanoclusters dispersed in a matrix of amorphous Li2O, then the alloying reaction between Li and Sn occurs, giving rise to LixSn at the end of the 1st charge. The conversion reaction was shown to be partially irreversible during the following delithiation; however the Li2O matrix plays a major role in the cycling stability of SnO2 since it buffers the volume expansion occurring during Li reaction with Sn, and prevents the Sn particle growth during cycling (Pelliccione, Timofeeva, and Segre 2016).
In our study, electrochemical performance of SnO2-graphite electrodes has been investigated. In such electrodes graphite provides good electrical conductivity, Li mobility through the electrode, and lowers the average potential; SnO2 instead acts as a specific-charge-enhancing component. The influence of different parameters, such as amount of SnO2, binder, electrolyte additive, and voltage cut-off have been studied to determine the best cycling conditions for a long term cycling (>100 cycles). Furthermore, a post-mortem physicochemical analysis was carried out to understand the reasons of the capacity fading. A capacity retention of 98% after 100 cycles was obtained for electrodes with 50wt.% SnO2, PAA/CMC binder and FEC electrolyte additive.
Berg, Erik J., Claire Villevieille, Daniel Streich, Sigita Trabesinger, and Petr Novák. 2015. Journal of the Electrochemical Society, 162: A2468-A75.
Courtney, Ian A., and J. R. Dahn. 1997. Journal of the Electrochemical Society, 144: 2045-52.
Pelliccione, Christopher J., Elena V. Timofeeva, and Carlo U. Segre. 2016. The Journal of Physical Chemistry C, 120: 5331-39.
11:45 AM - ES04.16.05
The Properties of a Three-Dimensional Porous Electrode Made from Cu Nanowires
Benjamin Wiley 1 , Myung Jun Kim 1 , Feichen Yang 1
1 , Duke University, Durham, North Carolina, United States
Show AbstractThe high surface area per unit volume and large mass-transfer rates offered by three-dimensional porous electrodes have resulted in their use in a wide variety of electrochemical processes, including organic electrosynthesis, water electrolysis, water treatment, fuel cells, and redox flow batteries.1-4 Many types of porous electrodes are commercially available, including carbon paper, graphite felt, reticulated vitreous carbon (RVC), metal mesh, and metal foam. Metal foam offers relatively high conductivity (1.5x10-5 ohm m) but low surface area (<4x104 m-1),5 whereas carbon paper has one of the highest surface areas (up to 1.6x105 m-1) but lower conductivity (4.7x10-5 ohm m).6
This presentation will describe the characteristics of a copper nanowire electrode that has 15 times more surface area (2.4x106 m-1) and is 33 times more conductive (1.6x10-6 ohm m) than carbon paper. The improvement in surface area is due to the small diameter of the nanowires relative to carbon fibers in carbon paper, whereas the high conductivity is due to intrinsically higher conductivity of Cu, and the fact that the metal nanowires can be sintered together, forming highly conductive inter-nanowire contacts. The porosity of the nanowire electrode is 0.94. This presentation will report the electrochemical performance of the Cu nanowire electrode relative to commercial flow through electrodes for several electrochemical applications, including metal ion reduction, redox flow batteries, and water splitting. Experimental results will be compared to comsol simulations. The high-conductivity, high surface area, and high porosity that can be achieved with Cu nanowire electrodes creates new opportunities for improving the performance of electrochemical systems for energy storage, hydrogen production, water treatment and the production of fine chemicals.
References:
1. J. Newman, and W. Tiedemann, AIche J., 21, 25 (1975).
2. R. Alkire, and P.K. Ng, J. Electrochem. Soc., 124, 1220 (1977).
3. J.M. Friedrich, C. Ponce-De-Leon, G.W. Reade, and F.C. Walsh, J. Electroanal. Chem., 561, 203 (2004).
4. S. Porada, L. Weinstein, R. Dash, A. van der Wal, M. Bryjak, Y. Gogotsi, and P. M. Biesheuvel, ACS Appl. Mater. Interfaces, 4, 1194 (2012).
5. S. Langlois, and F. Coeuret, J. Appl. Electrochem., 19, 43 (1989).
6. S.C. Barton, Y. Sun, B. Chandra, S. White, and J. Hone, Electrochem. Solid-State Lett., 10, B96 (2007).
ES04.17: In Situ Characterization and Operando Techniques III
Session Chairs
Ekaterina Pomerantseva
Gleb Yushin
Thursday PM, November 30, 2017
Hynes, Level 3, Ballroom A
1:30 PM - ES04.17.01
Inkjet Printed Energy Storage Systems for Electrochemical Testing and In Situ TEM Analysis
Lorcan McKeon 1 2 , João Coelho 1 3 , Edmund Long 2 , Oskar Ronan 1 3 , Chuanfang (John) Zhang 1 , Valeria Nicolosi 1 3
1 CRANN, Trinity College Dublin, Dublin Ireland, 2 School of Physics, Trinity College Dublin, Dublin Ireland, 3 School of Chemistry, Trinity College Dublin, Dublin Ireland
Show AbstractIn recent years there has been a surge in development and research into the synthesis and properties of materials at the nano-scale. Nanoscale materials exhibit interesting physical, chemical and electrical properties not seen in their bulk counterparts and represent an exciting opportunity for developing new and improved technologies. At a time when renewable and decentralised power production is becoming more commonplace, developing effective means of energy storage is increasingly important. The electronic and chemical properties of layered nanomaterials and other nano structures could vastly improve conventional energy storage devices such as Li ion batteries and more exotic devices such as supercapacitors.
There has been in depth research conducted into an array of synthesis techniques of nanomaterials such as mechanical exfoliation, liquid phase exfoliation1. In this work we aim to show the next step in this development cycle of these new devices, namely the manufacture of full scale supercapacitors through inkjet printing. This technique offers the simplest and lowest cost method of developing a variety of device designs on our choice of substrates using a range of nano materials. Our material can be synthesised through liquid phase exfoliation, giving us a simple, and rapid two-step process of device manufacture, where materials, substrates and designs can be changed and adapted with relative ease.2 We show in this work our ability to produce all inkjet printed supercapacitors using MnO2, graphene and carbon nanotubes on flexible, transparent and non-transparent substrates including PET and Kapton.
In addition, we show how this process can be used as a rapid and low impact method to fabricate devices on SiN liquid cell TEM chips for in-situ electrochemical testing. These cells can be inserted into the TEM and filled with electrolytes of our choice allowing for real time analysis of our chosen electrode material as the cell charges and discharges. No extensive treatment process is required for these TEM cells, and it represents a far faster method of deposition than standard FIB manufacture3, and has been found to cause less damage to the cells liquid cells. This has enabled us to probe the chemical and physical evolution of both supercapacitive and battery materials during the energy storage process.
References
(1) Nicolosi, V.; Chhowalla, M.;Kanatzidis, M. G.; Strano, M. S.; Coleman, J. N. Science 2013, 340
(2) David J. Finn, Mustafa Lotya, Graeme Cunningham, Ronan J. Smith, David McCloskey, John F. Donegan and Jonathan N. Coleman J. Mater. Chem. C,2014, 2, 925
(3) Meng Gu, Lucas R. Parent, B. Layla Mehdi, Raymond R. Unocic, Matthew T. McDowell, Robert L. Sacci, Wu Xu, Justin Grant Connell, Pinghong Xu, Patricia Abellan, Xilin Chen, Yaohui Zhang, Daniel E. Perea, James E. Evans, Lincoln J. Lauhon, Ji-Guang Zhang, Jun Liu, Nigel D. Browning, Yi Cui, Ilke Arslan, and Chong-Min Wang Nano Letters 2013 13 (12), 6106-6112
1:45 PM - ES04.17.02
In Situ Measurement of Phase Boundary Kinetics in Battery Electrodes Using Picosecond Ultrasonics Method
Shaghayegh Rezazadeh Kalehbasti 1 , LiWei Liu 1 , Humphrey Maris 1 , Pradeep Guduru 1
1 , Brown University, Providence, Rhode Island, United States
Show AbstractPicosecond ultrasonics is a pump-and-probe technique that uses ultra-short light pulses to detect the internal features of a sample under study. We have utilized this method to conduct precise, non-destructive in-situ measurement of the kinetics of phase boundary propagation inside silicon during lithiation. For this purpose, a custom-made electrochemical cell is designed to enable cycling of the battery half-cells under ambient condition. The results give clear visualization of the position of the reaction front. The advantages of this approach include the use of single crystal wafer samples of well-defined geometry and electrochemical parameters such as current density and potential, and an ability to “see” inside the material to determine the phase boundary velocity, obviating the necessity for any assumptions or ex-situ examination, which may result in change in the state of the material during sample preparation. A moving boundary model is proposed to extract the relevant kinetic parameters from the experimental data.
2:00 PM - ES04.17.03
Conversion Reaction Mechanism with Preferred Orientations in Tunnel-Structured Alpha-MnO2 Lithium-Ion Battery Electrode Investigated by In Situ Transmission Electron Microscopy
Seung-Yong Lee 1 2 , Lijun Wu 2 , Altug Poyraz 2 3 , Amy Marschilok 3 , Kenneth Takeuchi 3 , Esther Takeuchi 3 2 , Miyoung Kim 1 , Yimei Zhu 2
1 , Seoul National University, Seoul Korea (the Republic of), 2 , Brookhaven National Laboratory, Upton, New York, United States, 3 , Stony Brook University, Stony Brook, New York, United States
Show AbstractDespite their high energy density, lithium-ion batteries are still the subject of intensive investigation for the realization of battery-only electric vehicles using green resources. Manganese oxides, due to their low cost and eco-friendliness, have been considered as attractive energy materials in various types of energy storage devices including lithium-ion battery. In particular, α-MnO2 has unique one-dimensional [2 × 2] tunnels, which can be a great advantage for lithium-ion battery electrodes by facilitating the insertion and extraction of lithium-ions. Thanks to the effective tunnel structure, α-MnO2 can be applied to both of positive and (cathode) negative electrodes (anode) in lithium-ion battery; the cathode through the exceptional insertion reaction and the anode through the conversion reaction as general metal oxide materials. The superior performance of α-MnO2 electrodes in lithium-ion batteries has been attributed to the unique tunnel structure, however, the detailed role of the tunnels and the precise electrochemical reaction mechanisms are not well understood.
We investigated the detailed lithiation mechanism in a single K+-stabilized α-MnO2 nanowire up to full lithiation state by in situ transmission electron microscopy (TEM) study. First of all, we verified that the lithiation through the longitudinal [2 × 2] tunnels is preferable than penetration through the side-wall of the nanowires by elaborately modifying the in situ TEM experimental technique, which demonstrates the fastest lithium-ion diffusion path in the α-MnO2 electrode. Moreover, we demonstrated the MnO intermediate phase evolution, and revealed the development of the MnO and Li2O phases with perferred orientations during the conversion reaction procedure, attributed to the tunnel structure. The crystal orientation relationship between the original and developed phases, and further lithiation mechanisms of α-MnO2 will be discussed. These findings clearly explain how lithium ions insert and react with the elements in the α-MnO2 material. In addition to the MnO2 material, this work can provide insight into the electrochemical reaction mechanisms of various metal oxide electrode materials.
2:15 PM - ES04.17.04
Electrochemical Properties of Chemically Controlled Eumelanin
Ri Xu 1 , Tania Prontera 2 3 , Eduardo Di Mauro 1 , Francesca Soavi 4 , Alessandro Pezzella 2 , Clara Santato 1
1 , Polytechnique Montreal, Montreal, Quebec, Canada, 2 , University of Naples Federico, Napoli Italy, 3 , l'energia e lo sviluppo economico sostenibile , Portici Italy, 4 , University of Bologna, Bologna Italy
Show AbstractEumelanin is a brown-black pigment, ubiquitous in the human body, obtained from the oxidative polymerization of 5,6-dihydroxyindole (DHI) and/or 5,6-dihydroxyindole-2 carboxylic acid (DHICA). The pigment features interesting functional properties, such as photoprotection, hydration dependent conductivity and free radical scavenging [1].
Melanin-based electrodes for supercapacitors and batteries have been recently demonstrated [2][3]. Nevertheless, due to the limited processability of eumelanin, the redox properties of eumelanin – based on the presence of the quinone/semiquinone redox couple in the molecular structure - are at presently largely undiscovered, thus limiting the exploitation of the full technological potential of the biopolymer. Controlling the (supra)molecular structure is indeed imperative to understand the electrochemical properties of eumelanin.
Here we report on the redox properties of chemically controlled eumelanin, solid state polymerized on carbon paper from the two building blocks, DHI (leading to DHI-melanin) and DHICA (leading to DHICA melanin). DHI-melanin and DHICA-melanin were investigated by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS) curves in pH5 aqueous acetate electrolytes differing for their cation (NH4+, K+, Na+, Cu2+). Broad cathodic and anodic peaks are clearly observable in the voltammograms of DHI and DHICA-melanin with higher currents measured for polyDHI likely due to a better pi-pi stacking obtained in this polymer with respect to polyDHICA (that includes carboxylic groups). With respect to electrolytes including NH4+, K+ and Na+ dramatic changes are observed in presence of Cu2+, a cation with a high binding affinity for eumelanin. Voltammetric results are in agreement with impedance results obtained at different applied electrical biases. Our results constitute the underpinning for the optimal use of eumelanin in energy storage systems employing multivalent ions. They also contribute to gain insight on the role played by eumelanin on the control of ion fluxes in biological systems [4].
2:30 PM - ES04.17.05
Spectroscopic Insight into the Oxide Electrocatalyst/Water Interface
Kelsey Stoerzinger 1 , Ryan Comes 2 , Steven Spurgeon 1 , Suntharampillai Thevuthasan 1 , Yingge Du 1 , Scott Chambers 1
1 , Pacific Northwest National Laboratory, Cambridge, Massachusetts, United States, 2 Department of Physics, Auburn University, Auburn, Alabama, United States
Show AbstractThe intermittent nature of renewable energy sources requires storage and conversion of energy in a clean, scalable manner. Water electrolysis and hydrogen fuel cells present a promising solution, however the overall efficiency is limited by the oxygen evolution and reduction reactions (OER and ORR), resulting in the use of precious metals to reduce the kinetic overpotential. In alkaline environments, transition metal oxides present an alternative to noble metals for oxygen electrocatalysis. However, a lack of fundamental understanding of the reaction mechanism and interfacial interactions has hindered their rational design.
Investigation of epitaxial oxide thin films allows examinations of their chemical speciation in an aqueous environment using ambient pressure X-ray photoelectron spectroscopy.1 By quantifying the formation of hydroxyl groups in situ, we compare the relative affinity of different surfaces for this key reaction intermediate in oxygen electrocatalysis.2 The coverage of hydroxyl groups measured spectroscopically at a fixed relative humidity trends with the free energy of a hydroxylated surface calculated by density functional theory, providing an experimental handle on the binding strength of this reaction intermediate.3 Understanding oxide electronic structure in an aqueous environment is also critical for promoting charge transfer reactions in both electrocatalytic and photocatalytic reactions. To this end, we investigate changes in the electronic structure as a function of the oxygen and water chemical potential, enabling comparison with the metal redox potential and catalytic activity. This fundamental molecular-level understanding of interfacial interactions developed from epitaxial surfaces can guide the rational design of high-surface-area oxide catalysts for technical applications.
References
1. K.A. Stoerzinger, W.T. Hong, E.J. Crumlin, H. Bluhm, and Y. Shao-Horn, Accounts of Chemical Research, 48, 2976 (2015).
2. K.A. Stoerzinger, R. Comes, S.R. Spurgeon, S. Thevuthasan, K. Ihm, E.J. Crumlin, S.A. Chambers. J. Phys. Chem. Lett. 8, 1038 (2017).
3. K.A. Stoerzinger, W.T. Hong, G. Azimi, L. Giordano, Y.-L. Lee, E.J. Crumlin, M.D. Biegalski, H. Bluhm, K.K. Varanasi, Y. Shao-Horn. J. Phys. Chem. C 119, 18504 (2015).
2:45 PM - ES04.17.06
Multi-Scale Image-Based Characterization of Electrochemical Energy Material System
Shawn Zhang 1 , J. Jankovic 2 , A. M. V. Putz 2 , D. Susac 2 , J. Chen 1
1 , DigiM Solution LLC, Burlington, Massachusetts, United States, 2 , AFCC Automotive Fuel Cell Cooperation Corp., Burnaby, British Columbia, Canada
Show AbstractModern electrochemical energy storage and power generation devices depend on microstructures. However, each functional layer or component of these devices has a distinctive characteristic length scale, which leads to increasing heterogeneity in its design. For instance, proton exchange membrane fuel cells (PEMFCs) are being developed as alternative energy sources for both residential and automotive applications. The multi-layered membrane electrode assembly (MEA) has length scales that span six orders of magnitude, from several nanometers of the catalyst particle size in the cathode and anode catalyst layer (CL) to hundreds of micrometers of the carbon fibers in the porous gas diffusion layer (GDL). The design, characterization, and optimization of the structures demands both high resolution and device-scale representativeness, often seen as orthogonal requirements that are difficult, if not impossible, to achieve simultaneously.
Rapid development in three-dimensional (3D) microscopy techniques increasingly answers to the resolution challenge at various scales. Combining with artificial intelligence and high performance computing, the massive amount of 3D imaging data at various scales can be integrated. Multi-scale image-based simulation, as a new characterization workflow, offers the potential of a paradigm change in the characterization of electrochemical energy material systems.
Using PEMFCs as a template system, this presentation reports that Transmission Electron Microscope (TEM) tomography (TEM, 0.6nm resolution), Focused Ion Beam - Scanning Electron Microscope tomography (FIB-SEM, 2.5-10nm resolution) and Micro-Computed Tomography (MicroCT, 0.3-10micron resolution) are correlatively employed to image MEA at different scales. Unified structural characterization is achieved via combining 3D imaging data at multiple scales. An up-scaling approach based on TEM, FIB-SEM and MicroCT reconstruction of catalyst layer , micro-porous layer and porous GDL are developed to accurately predict electrical and fluid transport properties, which compares favorably with experimental and literature data. In addition to the benefit of direct visualization of microstructures at various scales, this approach overcomes various difficulties and challenges from physical experiments. The framework is being applied to different electrochemical energy materials including solid oxide fuel cell, lithium battery, magnesium battery, and solar energy materials.
ES04.18: Electrode Materials III
Session Chairs
Babu Chalamala
Guiliang Xu
Thursday PM, November 30, 2017
Hynes, Level 3, Ballroom A
3:30 PM - ES04.18.01
Modeling Electrolyte Influence on LiMn2O4 Battery Cathodes Functionalized with Self-Assembled Monolayers
Kendra Letchworth-Weaver 1 , Bruno Giuliano Nicolau 2 , Yasaman Ghadar 1 , Christopher Knight 1 , Andrew Gewirth 2 , Ralph Nuzzo 2 , Maria Chan 1
1 , Argonne National Laboratory, Lemont, Illinois, United States, 2 Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois, United States
Show AbstractCreating an artificial cathode-electrolyte interface (CEI) from self-assembled monolayers of phosphonic acids offers a promising avenue to prevent capacity loss in Li-ion batteries due to metal dissolution from the cathode. A complete theoretical description of the complex and inherently multi-scale interface between the battery electrode surface and an organic electrolyte can enable rational design of such functionalized cathode coatings. We first present a microscopically informed continuum model for organic electrolyte [1,2] which reproduces key solvation phenomena relevant to battery operation. We go on to predict how the structure and energetics of the metal oxide cathode in Li-ion batteries change due to the presence of liquid electrolyte. We find that compared to vacuum calculations [3], the voltage stability window of the Li-terminated (001) and (111) surfaces of the spinel LiMn2O4 (LMO) cathode in solution is enhanced. Furthermore, we demonstrate that our solvation model, in combination with density-functional theory and classical molecular dynamics, simultaneously captures both the formation of a stable artificial CEI on the LMO surface and the interaction of the CEI molecules with the electrolyte. Our theoretical description captures the experimentally observed trends in solubility and cyclic voltammetry of the coated LMO surface, demonstrating how adjusting the length and functionalization of the phosphonates can balance the competing needs of maximizing Li-ion conductivity but minimizing cathode dissolution.
Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
[1] K. Letchworth-Weaver and T.A. Arias, Phys. Rev. B. 86, 075140 (2012).
[2] D. Gunceler et al, Modelling Simul. Mater. Sci. Eng. 21,074005 (2013).
[3] R. Warburton et al, ACS Applied Materials and Interfaces, 8 (17), 11108–11121 (2016).
3:45 PM - ES04.18.02
Improvement of VRFB Performance by Using Catalytically Etched Carbon Papers as Electrodes
Saleem Abbas 1 4 , Jinyeon Hwang 1 2 , Sheeraz Mehboob 1 4 , Hyun-Jin Shin 1 3 , Heung Yong Ha 1 4
1 Center for Energy Convergence Research, Korea Institute of Science and Technology (KIST), Seoul Korea (the Republic of), 4 Division of Energy and Environment Technology, Korea University of Science and Technology (KIST), Seoul Korea (the Republic of), 2 Division of Energy and Environmental Science and Technology, University of Science and Technology (UST), Seoul Korea (the Republic of), 3 Chemical and Biological Engineering, Korea University, Seoul Korea (the Republic of)
Show AbstractThe environmental aspects of fossil fuels and depletion of their reservoirs are main reasons for the growing use of renewable energy sources and environmentally sustainable storage technologies in recent years. Solar, wind, biomass and tidal are among climate-friendly energy sources. But the integration of these sources into large scale grid application is limited by their intermittent nature. Electrical energy storage (EES) technology solves this issue by storing energy on large scales. Redox flow batteries (RFBs) due to unique advantages of design flexibility, long cycle life, decoupled scaling of power and energy, are amongst suitable candidates of EES. All Vanadium Redox Flow Battery (VRFB) introduced in 1980s has advantage over conventional RFBs as it employs four different oxidation states of vanadium; V4+/V5+ to cathode side and V2+/V3+ to anode side hence minimizes crossover effect through membrane. A typical VRFB contains two electrolyte reservoirs connected to cell sandwiching an ion exchange membrane between electrodes. V4+ is oxidized to V5+ on cathode while V3+ is reduced to V2+ on anode during charging and these charged species are reversed back during discharging.
Carbon paper or felt due to its large reactive surface area, chemical stability in highly acidic solution has been widely used as electrode in VRFB, however poor electrochemical activity, low kinetics toward oxidation and reduction of vanadium ions, and less wettability arising from its hydrophobic nature limit its wide-spread application. Several modification techniques have been used to improve the catalytic activity of carbon electrode toward vanadium redox couples mainly including thermal, chemical and electrochemical treatments. Most of the modification techniques result increased activity of carbon electrode attributed to its enhanced available surface area and surface functional groups. In this work carbon paper is etched by using cobalt oxide (Co3O4) as catalyst and is used as electrode for vanadium redox flow battery cell. The etched carbon paper is found better than pristine one in terms of charging overpotential, IR drop, charge/discharge capacities and energy efficiency at all working current densities. Etched carbon paper showed almost 31.0 Ah/L discharge capacity at initial working current density of 50 mA/cm2 compare to 16.0 Ah/L of pristine one, While 16 Ah/L at 150 mA/cm2 where pristine and thermally treated (TT) carbon paper have no performance. Similar effect was noticed in terms of energy efficiency, the etched carbon paper showed 70% energy efficiency at 150 mA/cm2 which is dramatically higher than pristine and thermally treated carbon paper electrodes. The improved performance is attributed to increased surface area, wettability and presence of microscopic pores on the surface of etched carbon paper.
4:00 PM - ES04.18.03
ReaxFF Simulations Study of Novel Nanoporous Carbon Structures Coming from Agave Residues—Insights into the Design of Carbon Electrodes for Energy Storage Devices
Jesús Muñiz 1 , Sergio Marroquín 2 , Gerardo Gutiérrez 2 , L.M. Mejía-Mendoza 1 , A.K. Cuentas-Gallegos 1
1 Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco Mexico, 2 Programa Académico de Ingeniería en Energía, Universidad Politécnica de Chiapas, Suchiapa, Chiapas, Mexico
Show AbstractElectrode materials for energy storage devices based on carbon have shown to be a reliable choice to be implemented in supercapacitors or Li-ion batteries. The development of novel carbon materials is of high relevance to provide improvements in the performance of such devices. The use of eco-friendly materials coming from biomass waste for this purpose may represent a breakthrough in this area of research. The aim of this study is to give new theoretical insights into the in silico design of carbon materials based upon organic molecules that may be found in the agave waste residues. We performed quenching calculations using the Verlet + Berendsen thermostat with Molecular Dynamics at the ReaxFF level [1]. We combined classical dynamics and quantum-mechanical corrections coming from DFT parameters, as well as the corrections of dispersive interactions of the van der Waals-type. We considered the molecular model of Alder’s softwood lignin C160H180O58 as the precursor material in the bio-nanofiber contained in the agave waste residue. A randomized model of 40-100 lignin molecules was thermally quenched in the simulation starting from room temperature to a a critical temperature of 1280 K. All samples were analyzed with different heating rates ranging from 0.4 to 40 K/ps and they were all stabilized to the starting temperature to complete the process. The char formation was characterized as nanoporous carbon by considering structural parameters such as density and RDF distributions. The comparison of these results with experimental data obtained in solar pyrolisis available in our group, reveal a reasonable agreement. These results may aid in the design of carbon electrodes for energy storage devices and other applications with desirable predictable properties.
1. A. C. T. van Duin, S. Dasgupta, F. Lorant, W. A. G. III, ReaxFF: A Reactive Force Field for Hydrocarbons, J. Phys. Chem. 105 (2001) 9396–9409.
4:15 PM - ES04.18.04
Nanofluidic Battery—Ion Transport near Electrodes under Nanoscale Confinement
Sylvia Xin Li 1 , Nam Kim 2 , Kim McKelvey 3 , Chanyuan Liu 2 4 , Henry White 3 , Sang Bok Lee 2 , Gary Rubloff 2 , Mark Reed 1
1 , Yale University, New Haven, Connecticut, United States, 2 , University of Maryland, College Park, Maryland, United States, 3 , The University of Utah, Salt Lake City, Utah, United States, 4 , Lam Research, Portland, Oregon, United States
Show AbstractElectrical energy storage (EES) is a fast growing field drawing tremendous attention from both scientific community and industry, due to the increasing demand in a broad range of applications such as portable electronics, electric vehicles, and grid storage. To achieve high performance EES applications, much effort has been devoted to developing nanostructured materials with novel architecture design. Nanostructures offer the advantage of high surface area and short transport time, but at the cost of a highly confined electrolyte. Therefore, it is essential to understand ion transport under confinement to provide guidance to overcome limitations and optimize designs of nanostructured energy storage materials.
We have developed a novel nanofluidic cell for investigating ionic transport in battery storage materials when the electrolyte is highly confined. A confinement of 20nm is achieved, enabling the study of electrochemistry when neighboring electric double layers (EDLs) start to overlap. Such nanofluidic cells are fabricated via microfabrication and benefit from well-defined geometries at different length scales. Atomic layer deposition (ALD) is utilized for the well-controlled deposition of battery storage materials. We have succeeded in conducting both experiments and simulations of a model system with TiO2 electrodes for lithium storage. From cyclic voltammetry measurements at different concentrations in comparison with a bulk system, intriguing phenomena are observed such as enhancement of peak current, shift of peak positions and increase of specific capacity. These observations can be explained by the overlap of EDLs, which creates a unique electrolyte environment of asymmetric cation/anion distribution. More importantly, these nanofluidic cells can serve as a general platform with highly controllable architecture design and opens up exciting possibilities to offer mechanistic insight into complex EES systems.
4:30 PM - ES04.18.05
Understanding the Catalyst-Photocathode Interface to Enable High Performance Earth Abundant HER Catalysts
James Thorne 1 , Yanyan Zhao 1 , Da He 1 , Shizhao Fan 2 , Srinivas Vanka 2 , Zetian Mi 3 , Dunwei Wang 1
1 , Boston College, Chestnut Hill, Massachusetts, United States, 2 , McGill, Montreal, Quebec, Canada, 3 , University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States
Show AbstractPhotoelectrochemical (PEC) hydrogen evolution is an appealing means to store solar energy. A simple semiconductor liquid interface offers potentially high solar to hydrogen efficiencies, while posing as an interesting physics, materials, and chemistry system to study. In order to maximize the power output of photocathodes, used for the hydrogen evolution reaction (HER), catalysts, such as Pt, are needed at the semiconductor liquid interface (SCLI). The addition of a heterogeneous catalyst on the surface of the semiconductor often greatly enhances the harvested photovoltage of the PEC system, and thus the onset potential for the HER. However, the true nature of how the catalyst improves the onset potential remains poorly understood and remains a limiting factor in achieving PEC HER. Using intensity modulated photocurrent spectroscopy (IMPS) we have probed charge recombination and charge transfer in relation to the onset potential for HER. We find that Pt improves the HER kinetics as well as drastically reduces charge recombination at the SCLI. Using the electron scavenger, sodium persulfate, and Ag we show that the onset potential can be improved separately by improving the reaction kinetics or reducing SCLI recombination, respectively. Furthermore, we find that the earth abundant HER catalysts, such as CoP, is less efficient at accepting charges at lower applied potentials and may benefit from metallic interlayers. Together our study sheds light on the catalyst semiconductor interface and is an important step in understanding how to maximize the power in PEC HER systems.
4:45 PM - ES04.18.06
Chemical Vapor Deposition (CVD) of Iron Phosphate onto Carbon Nanotubes (CNT) for Flexible High-Power Battery Applications
Kostiantyn Turcheniuk 1 , Xiaolei Ren 1 2 , Daniel Lewis 1 , Alexandre Magasinski 1 , Gleb Yushin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, Chongqing, China
Show AbstractHigh safety standards, low environmental impact and low cost of polyanion compounds having structure XO43- (where X=P, W, Mo, S) have triggered much interest in electrochemical energy storage applications.[1, 2] Within the polyanion-type cathode materials for lithium (Li) - ion batteries, LiFePO4 (LFP) and FePO4 attracted the most attention because of stable reversible Li insertion/extraction reaction operating in the voltage range 2.5 – 4.0 V [3] and good rate when carbon-coated [4]. Without carbon coatings, the practical realization of theoretical capacity of these active materials (178 mAh g-1) is typically challenging due to their low electronic and ionic conductivity; in addition, phase transformations and resulting mechanical instability of these compounds in bulk limit their performance further.[1] The best LFP cathode performance can be achieved by forming carbon-containing nanocomposites.[5] Unfortunately, traditional synthesis routes offer limited control over uniformity and dimensions of LFP grains.
Chemical vapor deposition (CVD) offer precise compositional and dimensional control of coatings and the applications of CVD in energy storage is growing rapidly [6]. In this work, we for the first time have designed a CVD synthesis process for FePO4 deposition [7]. We have further applied this process for the deposition of uniform FePO4 coatings onto the carbon nanotube (CNT) surface. By rigorously controlling the FePO4 layer thickness, we systematically studied electrochemical performance of CNT@FePO4 composites to balance high rate with high volumetric and specific capacities. Flexibility and excellent mechanical properties of the produced electrodes show great promises of this technology for multifunctional batteries with high power performance.
References
1. Nitta, N., et al., Li-ion battery materials: present and future. Materials Today, 2015. 18(5): p. 252-264.
2. Armand, M. and J.-M. Tarascon, Building better batteries. Nature, 2008. 451(7179): p. 652-657.
3. Padhi, A.K., K. Nanjundaswamy, and J.B. Goodenough, Phospho-olivines as positive-electrode materials for rechargeable lithium batteries. Journal of the Electrochemical society, 1997. 144(4): p. 1188-1194.
4. Chen, Z. and J. Dahn, Reducing carbon in LiFePO4/C composite electrodes to maximize specific energy, volumetric energy, and tap density. Journal of the Electrochemical Society, 2002. 149(9): p. A1184-A1189.
5. Yamada, A., S.-C. Chung, and K. Hinokuma, Optimized LiFePO4 for lithium battery cathodes. Journal of the Electrochemical society, 2001. 148(3): p. A224-A229.
6. Wang, X. and G. Yushin, Chemical vapor deposition and atomic layer deposition for advanced lithium ion batteries and supercapacitors. Energy & Environmental Science, 2015. 8(7): p. 1889-1904.
7. Ren, X., et al., Chemical Vapor Deposition (CVD) of Amorphous Iron Phosphate onto Carbon Nanotubes for Flexible High-Power Energy Applications, in press.
ES04.19: Poster Session IV
Session Chairs
Friday AM, December 01, 2017
Hynes, Level 1, Hall B
8:00 PM - ES04.19.01
SnO2 Thin Films as an Efficient Anode Material for Na-Ion Battery
Rasmita Biswal 1 , Venimadhav Adyam 1 , Debasis Nayak 1 , S. Janakiraman 1 , Sudipto Ghosh 1
1 , Indian Institute of Technology, Kharagpur, Kharagpur India
Show AbstractNa-ion batteries can be the key to fulfilling the future energy requirement because of the huge availability of sodium, its low price and the similarity of both Li and Na insertion chemistries. The purpose of this paper is to show SnO2 thin films as an efficient anode material for Na-ion thin film battery. SnO2 thin films were prepared by pulsed laser deposition (PLD) techniques. The laser used was a KrF excimer laser producing pulse energies of about 300 mJ at a wavelength of 248 nm and a frequency of 10 Hz. X-ray diffraction (XRD) and Raman scattering spectra of the PLD SnO2 films deposited at different deposition temperatures under an oxygen background pressure of 300 mTorr are composed of a polycrystalline SnO2 phase. SnO2 thin films are showing the discharge capacity of 325 mAh g-1 and maintained stable cyclability up to 50 cycles at a 10C rate in the voltage window of 0.005V to 2 V. The improved cyclability of the SnO2 thin film could be mainly ascribed to the reversible Na–Sn alloying and de-alloying reactions. The stable cyclability is attributed to the retardation of the aggregation of Sn during cycling by the Na2O matrix.
8:00 PM - ES04.19.02
Graphene Oxide-Nafion Interface Enhanced Performance of Proton Exchange Membrane (PEM) Fuel Cells
Likun Wang 1 , Hongfei Li 1 , Cheng Pan 1 , Yuchen Zhou 1 , Miriam Rafailovich 1
1 , Stony Brook University, Stony Brook, New York, United States
Show AbstractProton exchange membrane fuel cells (PEMFCs) have attracted tremendous attention as a promising green energy source due to the high energy converting efficiency, low operation temperature and none pollution emission. Numerous efforts have been made to improve hydrogen oxidation reaction and oxygen reduction reaction. However, CO poisoning, resulting from the impure fuel sources, hindered the commercialization of PEMFCs by blocking the catalytic active sites of platinum. Here, we reported a simple, low-cost and readily scalable method to mitigate this effect by graphene oxide (GO)-Nafion interface. In our study, a uniform singer layer of GO is deposited on the Nafion membrane by lifting it off from the air/water interface through Langmuir-Blodgett (LB) trough before incorporating into membrane electrode assembly (MEA). The maximum power output of the cell under H2/air atmosphere showed an enhancement of 35%. Furthermore, more than 100% increase is obtained when 0.1% carbon monoxide (CO) was introduced into H2 stream while only less than 10% of improvement was observed under H2/O2. The impact of GO-Nafion interface on the degradation of Pt catalyst was also investigated using cyclic voltammetry (CV) to further prove the elimination of CO poisoning effect. We, therefore, hypothesize that a synergetic effect is established between GO and Nafion in the removal of CO.
8:00 PM - ES04.19.03
Enhancing Proton Exchange Membrane (PEM) Fuel Cells Performance via Gold Palladium-Nafion Interface
Likun Wang 1 , Hongfei Li 1 , Cheng Pan 1 , Anatoly Frenkel 1 , Ping Liu 2 , Miriam Rafailovich 1
1 , Stony Brook University, Stony Brook, New York, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States
Show AbstractGreat attention has been paid to proton exchange membrane fuel cells as a promising alternative energy source because of the high power output density, low operation temperature and pollution-free emission. In commercial market, the catalytic poisoning effect from the impurity of the gas flow, like CO, is one of the reasons that decrease the performance and stability of PEM fuel cell. Previous work has reported that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate are the perfect catalysts of the CO oxidization. In this approach, hydrophobic, thiol-functionalized AuPd nanoparticles were synthesized through two-phase method developed by Brust et al. The resulting AuPd nanoparticles have a random alloy structure rather than core-shell structure as suggested by X-ray absorption spectroscopy (XAS) results. Previously, we developed a technique to reproducibly form an Au nanoparticles layers with three atomic layers thick at the air/water interface. Now we use the same method to deposit these alloy particles directly onto the Nafion membrane in the PEM fuel cell by Langmuir–Blodgett trough, resulting in over 50% enhancement of the maximum output power. The enhancement is in agreement with density function theory (DFT) calculations which showed a reduction of energy barrier to CO oxidation, enabling the reaction to occur at lower temperatures.
8:00 PM - ES04.19.04
Effect of Oxide Layer Thickness on the Electrochemical Performance of Silicon Anodes for Lithium-Ion Batteries
Linghong Zhang 1 , Yuzi Liu 1 , Stephen Trask 1 , Zhenzhen Yang 1 , Wenquan Lu 1
1 , Argonne National Laboratory, Lemont, Illinois, United States
Show AbstractThe fast-growing demand for high-energy-density Li-ion batteries for use in electric vehicles and portable devices urges the development of the next-generation high-energy-density electrode materials. Comparative to commercial graphite anode materials, the naturally abundant silicon offers 10 times higher gravimetric capacity and 3 times higher volumetric capacity, making it a promising next-generation anode material.
When silicon is in contact with air, a native oxide layer of several nanometers will form. The actual thickness of the oxide layer may also vary due to the manufacturing processes. As the size of the silicon particle becomes smaller, this oxide layer will play a more important role as it takes up a larger volume and weight percentage. It has been reported that the presence of oxide layer harms the initial performance of the silicon anodes in a non-aqueous system. However, the effect of the oxide layer on the long cycling performance of the electrodes has not been well studied. Furthermore, with the current trend going towards water-based laminate making processes due to both electrode performance and economic reasons, the presence of oxide layer in the silicon electrodes is inevitable. Thus, it is very important to understand how the existence of oxide layer affects the electrochemical performance of silicon electrodes and furthermore optimize the electrodes based on the understanding.
Here we investigated the effect of oxide layer on the electrochemical performance of silicon anodes by growing the oxide layer of Si nanoparticles in a controlled manner. Si nanoparticles with an average size of 80 nm was used. LiPAA and carbon black was used to fabricate the electrodes. Brunauer-Emmett-Teller (BET) surface analysis, transmission electron microscopy as well as Fourier-transform infrared spectroscopy were performed to characterize the silicon nanoparticles. The stability of the silicon nanoparticles with different oxide layer thicknesses during electrode fabrication process is compared. Electrochemical performance of the silicon electrodes of different thicknesses was also analyzed and compared.
8:00 PM - ES04.19.05
Role of Cation Deficiency in Tuning the Electrochemical Performance of Nickel-Rich Layered Transition-Metal Oxides
Shuang Gao 1 , Mona Shirpour 1
1 Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States
Show AbstractAmong the extensively studied layered lithium mixed-transition-metal oxides (NCM: LiNi1-x-yCoxMnyO2), the compounds with high nickel concentrations (Ni-rich NCM) offer a combination of large electrochemical storage capacity, high operating potential, low cost and toxicity, and high elemental abundance. Therefore, Ni-rich NCM compounds are technologically, economically, and environmentally the most attractive compounds for high energy storage lithium-ion batteries. These compounds, however, typically exhibit poor structural and electrochemical stability majorly associated with the migration of cations and formation of antisite defects. This cation migration, also called cation mixing or cation disordering, can occur during materials synthesis processes and/or during electrochemical cycling, and escalates significantly when Ni content is increased. The formation of antisite defects and cation mixing leads to loss of active lithium site, impeded Li-ion diffusion, and surface reconstruction, resulting in capacity loss and reduced rate capability.
In this study, we have controlled the concentration of cation vacancies in nickel-rich NCM and found that cation vacancies play an important role in tuning the defect structure and electrochemical performance of nickel-rich NCM as a cathode compound in lithium-ion batteries. In this presentation, we will discuss the effect of cation vacancy on the structure, morphology, surface composition, and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 (NCM811) in pristine and cycled forms, and will propose strategies for enhancing the performance of high energy lithium-ion batteries.
8:00 PM - ES04.19.06
High Rate Performance in Dot-BaTiO3 Supported LiCoO2 Epitaxial Thin Film
Sou Yasuhara 1 , Yumi Yoshikawa 2 , Takashi Teranishi 2 , Shintaro Yasui 1 , Tomoyasu Taniyama 1 , Mitsuru Itoh 1
1 , Tokyo Institute of Technology, Yokohama Japan, 2 , Okayama University, Okayama Japan
Show AbstractLithium ion battery (LIB) is the most famous and useful secondary batteries. Some electric vehicles(EVs) using LIB are commercialized, but they need a half hour at least or more for battery charging. The issue of high-speed charging is that battery capacity decreases under large current charge/discharge. Improvement of high rate performance is essential for achievement of future desirable EVs. Previous studies conducted that oxide supported electrodes was very effective for improving high rate performance, but the detailed mechanisms were not clear. In this study, we focus on interface effect of oxide-cathode-electrolyte interface during charging and discharging of LIB.
To clarify the effect of this special interface, we focus on the interface between planar or dot BaTiO3(BTO) and LiCoO2(LCO) epitaxial thin film as a model. As the supported oxide materials, BTO was selected owing to existing the best performance among previous reports. We achieved to obtain well controlled interface between LCO cathode film and supported BTO. All films were fabricated by Pulsed Laser Deposition method. SrTiO3(STO) substrate was used because LCO could be grown on STO epitaxially. Two types of BTO was deposited on LCO epitaxial thin films; one was planarly coated BTO on LCO (Planar-type) and another was dot-like BTO on LCO (Dot-type). Crystal structure and surface or cross sectional images of fabricated thin films were evaluated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. After that, coin cells were assembled with Li as anode and LiPF6(EC : DEC = 3 : 7) as electrolyte. The charge-discharge measurements with stepwise increasing current density (1C-100C, 5 times each) for evaluation of C-rate performance were carried out.
As a result, all thin films of LCO were found highly crystallized and epitaxially grown on the substrate without any secondary phases. From microscopy images, Planar-type approximately 3 nm-BTO coated LCO and Dot-type dispersed 10 nm-BTO dots supported LCO were observed, respectively. From the result of charge-discharge measurement, Planar-type film showed worse performance at high rate than non-coated one because Li ion could not penetrate into BTO crystalline but pass through only in the vicinity of grain boundary. On the other hand, Dot-type sample showed better performance of 67 % capacity at 50C and 50 % at 100C than Bare sample with less 10 % capacity at 50 and 100C. This result indicates that three-phases interface of electrolyte, BTO-dot and electrode plays an important role for improving high rate performance, manifesting concentration of electric field at the three-phases interface enhance Li ion insertion/de-insertion. We will discuss the detail of the role of three-phases interface.
8:00 PM - ES04.19.07
New Polymeric Binders for Silicon/Graphite Composite Electrodes towards Improving the Practical Energy Density of Li-Ion Batteries
Xiuyun Zhao 1 , Chae-Ho Yim 1 , Naiying Du 1 , Yaser Abu-Lebdeh 1
1 , National Research Council Canada, Ottawa, Ontario, Canada
Show AbstractThere is a great interest in combining graphite with silicon as an anode material for lithium-ion batteries to increase their practical energy density, power density, and cycling life. [1] Our research group at National Research Council Canada has recently calculated the improvement in practical energy density of full Li-ion cells as a function of silicon content in the Si/graphite composite and found that the maximum improvement is about 17 % and it can be achieved by incorporating 15-25 wt % silicon into graphite. [2] This level of silicon content makes it possible to design a graphite-rich composite electrode that could be compatible with the current manufacturing processes.
It is well known that the binder plays a critical role to stabilize cycling performance of electrodes. Polyvinylidene fluoride (PVDF) and styrene-butadiene-rubber (SBR) are very popular binders for graphite electrode in industry, but they are not effective for Si electrodes. A number of binders have been investigated in literature for Si-based negative electrodes and stable cycling could be obtained by using polyimide binder or water-based binders based on poly(carboxylic acid)s and their alkali metal salts, such as carboxymethyl cellulose (CMC), poly(acrylic acid) (PAA), and alginate. However, to the best of our knowledge, so far very few binders have been designed specifically for Si/graphite composite electrodes.
Our research group has screened a number of natural or synthetic polymer binders including multifunctional, conductive polymer and copolymer binders specifically for the Si/graphite composite electrodes in the past few years. Here, we present a new type of binders based on natural polysaccharide dextran, and report its performance in graphite electrode, silicon electrode, and Si/graphite composite electrode. We investigated the properties of the binder and its impact on battery performance by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FTIR), Electrochemical Impedance Spectroscopy (EIS), peel-off test, and electrochemical performance test in lithium-ion cell. We found that the Si/graphite composite electrode with a 20/65 mass ratio shows a reversible capacity of about 525 mAh/g at a C/5 rate and has an excellent cycling stability when dextran binder was used, which is similar to the composite electrode with LiPAA binder and much better than that with PVDF. The good performance is believed to be caused by an interaction between function groups of dextran binder and active particles. The excellent performance of dextran combined with its non-toxicity, low cost, biodegradability and eco-friendly nature makes it an attractive binder material for Si/graphite composite electrodes in Li-ion batteries.
References
1. C. H. Yim, F. M. Courtel, Y. Abu-Lebdeh. J. Mater. Chem. A1, 8234, (2013).
2. C. H. Yim, S. Niketic, N. Salem, O. Naboka, and Y. Abu-Lebdeh, J. Electrochem. Soc., 164(1), A6294 (2017).
8:00 PM - ES04.19.08
Copper-Selective Alumina Membranes for High Temperature Electrochemical Measurements
Caspar Stinn 1 , Antoine Allanore 2
1 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Department of Material Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractSolid electrolyte membranes remain essential for the electrochemical investigation of solution thermodynamics via electromotive force (EMF) measurements in liquid systems. In the present study, copper (I) beta” alumina solid electrolyte was utilized to evaluate the thermodynamic properties of copper in solid and liquid metal alloys. Copper (I) beta” alumina of stoichiometry Cu5Mg2Al31O51 was synthesized through two methods: i) ion-exchange of sodium from sodium beta” alumina with molten copper (I) chloride, and ii) sintering of a mixture of copper (1) oxide, magnesium oxide, and aluminum oxide. Single crystals of copper (1) beta” alumina were grown in an optical floating zone furnace. To validate the performance of such membranes, the free energy and activity of copper in well-studied aluminum and steel alloys were first determined through EMF measurements. Following, copper (1) beta” alumina was explored as a promising candidate to construct reference electrode materials for copper-containing melts.
8:00 PM - ES04.19.09
Transition Metal Oxide-Based Conversion Reaction for High-Capacity Lithium-Ion Batteries
Eunho Cha 1 , Wonbong Choi 1
1 , University of North Texas, Denton, Texas, United States
Show AbstractThe increasing demand for high efficiency large-scale energy storage applications (e.g. electric vehicles) has led to an expansion in new developmental efforts for high energy-density lithium-ion batteries. However, commercial graphite anodes based on conventional intercalation reaction (involving insertion or extraction of Li ions into or from a layer-type crystal structure) have been faced with a low theoretical specific capacity which prevents them from being applied in advanced energy storages. Transition metal oxide-based conversion reaction (2yLi++ MxOy ↔ xM + yLi2O) could be a novel approach to resolve the aforementioned issues. Here, a facile method is used where layers of nickel oxide (NiO) were formed on 3D Ni substrate via thermal oxidation; subsequently, graphene layers were directly grown on the 3D NiO-Ni structure. Within this structure, porous 3D Ni substrate offers high surface area to form a large loading amount of NiO; also, graphene layers provide structural buffer against volume variations during cycling. Thus, enhanced electrochemical performance is achieved by extending the cycle life and by improving the areal capacity of LIB. The 3D graphene-NiO-Ni structure delivered around 28 mg cm-2 areal density and exhibited an areal capacity of 1.2 mAh cm-2 at 0.1 mA cm-2. The excellent properties and a novel design of the 3D graphene-NiO-Ni anode will contribute to the development of large-scale lithium ion batteris.
8:00 PM - ES04.19.10
Nanostructured Cathode Materials for Electrochemical Ammonia Synthesis
Joshua Fellowes 1 , Edman Tsang 1
1 , University of Oxford, Oxford United Kingdom
Show Abstract
Since its inception in 1913, the Haber-Bosch process has been one of the most important chemical processes for mankind, due to our reliance on nitrogen based fertilisers. Global demand for ammonia continues to grow, reaching 146 million tons in 20151. The drive for a more efficient way to synthesise ammonia is further incentivised by ammonias promise as an energy vector, with an energy density of 22.5 MJ/kg.2
By separating the reaction into electrochemical oxidation of hydrogen and electrochemical reduction of nitrogen, using a proton conducting membrane, the high-pressure requirement can be counterbalanced by consumption of electrical energy.3 For cells based on ceramic proton-conductors, the primary challenge remains maximising the triple phase boundary (TPD) of protons, electrons, and adsorbed nitrogen at the cathode.4 These requirements can be expressed as the need for a cathode material which can efficiently reduce nitrogen in the presence of protons. The most commonly reported cathode material is a Ag-Pd alloy.3 Common heterogenous catalysts such as Ru and Fe have proved to be far less active in electrochemical cells. There has been little development in maximising the TPD by use of nanostructured materials.
A series of doped-barium zirconate supports have been synthesised by sol-gel procedures. These materials have been used as supports for metal nanoparticles and their activity for heterogeneous ammonia synthesis investigated. Promising rates have been recorded so far, with noticeable differences between undoped and doped supports. We have started to apply these as cathode catalysts for electrochemical ammonia synthesis, preliminary rates are similar to those reported in literature.
TEM has been used to investigate the morphology of the nanoparticles, and the cell structure investigated by SEM. Phase identification was performed by XRD. The electrical properties of the cells are probed using electrochemical impedance spectroscopy.
1 Mineral Commodity Summaries 2015
2 R. Lan and S. Tao, Front. Energy Res., 2014, 2, 1.
3 V. Kyriakou, I. Garagounis, E. Vasileiou, A. Vourros and M. Stoukides, Catal. Today, 2017, 286, 2–13.
4 I. Garagounis, V. Kyriakou, A. Skodra, E. Vasileiou and M. Stoukides, Front. Energy Res., 2014, 2, 1.
8:00 PM - ES04.19.11
In Situ Growth-Mediated Bacterial Nanocellulose-Based Flexible Supercapacitor
Srikanth Singamaneni 1 , Qisheng Jiang 1 , Clayton Kacica 1 , Thiagarajan Soundappan 1 , Keng-Ku Liu 1 , Sirimuvva Tadepalli 1 , Pratim Biswas 1
1 , Washington University in St. Louis, St. Louis, Missouri, United States
Show Abstract
Recently, the development of flexible supercapacitors has received significant attention due to their application in flexible electronics such as bendable mobile phones, flexible displays and wearable devices. Owing to numerous advantages such as excellent mechanical strength, low cost, high porosity and natural abundance, bacterial nanocellulose (BNC) is considered to be highly attractive for the fabrication of flexible supercapacitors. This work demonstrates that BNC can serve as an ideal layered matrix for incorporation of active two-dimensional (2D) materials. A novel strategy for the incorporation of graphene oxide (GO) sheets into layered BNC during its growth is presented. GO flakes can be interlocked within nanocellulose network during BNC growth, enabling facile chemical reduction of GO sheets, which prevents their restacking and loss of active area, and leads to excellent energy storage performance as well as mechanical flexibility. Significantly, the fabrication approach demonstrated here can be extended to other 2D nanomaterials to realize flexible BNC-based energy storage devices.
8:00 PM - ES04.19.12
Predictions of Oxygen Reduction Reaction (ORR) on Face-Centered Tetragonal (FCT) Platinum-Iron Alloy Surface Using Density Functional Theory (DFT)
Shubham Sharma 1 , Andrew Peterson 1
1 , Brown University, Providence, Rhode Island, United States
Show Abstract
Platinum is considered to be the best elemental cathode material used in the proton exchange membrane-fuel cells (PEMFCs) [1]. However, it also accounts for the high cost of fuel cells. There have been significant progress in order to reduce the Platinum loading from fuel cells in the past decade. A substantial cost reduction further requires replacement of some platinum with less expensive electrocatalytic materials. There have been recent studies on Pt-Fe FCT alloys, which seem to perform better than pure platinum as an ORR catalyst [2]. In this study, PtFe FCT alloys have computationally been investigated as possible catalysts for oxygen reduction reaction (ORR) in PEMFCs. Here, we use density functional theory (DFT) to study the FCT structured PtFe alloy as potential catalysts for ORR by studying their detailed free-energy landscapes and comparing them with that of pure platinum. The work focuses on studying the strain, ligand and the structural effect responsible for the better ORR behavior of dealloyed FCT PtFe catalyst. We further study the behavior of the dealloyed catalyst as a function of thickness of platinum over-layers and its effect on the ORR activity.
8:00 PM - ES04.19.13
Transmission Electron Microscopy Study of Bubble Formation at Metallic Electrodes in Liquid Environment
Khim Karki 1 , Julio Rodriguez Manzo 1 , Daan Hein Alsem 1 , Norman Salmon 1
1 , Hummingbird Scientific, Lacey, Washington, United States
Show AbstractRecent advances in electron microscopy and x-ray instrumentation have made possible to study reactions happening at solid-liquid or solid-gas interfaces with high spatial resolution [1,2]. The challenge is keeping the fluid confined to a small area since vacuum conditions are required for optimal imaging conditions. This requirement is meet by using environmental cells with channels as thin as 0.1µm - 1µm made with microfabricated chips, which contain windows for observation and can be equipped with electrodes for biasing or heating purposes. This in-situ or operando approach, where reactions are induced and simultaneously quantified inside a microscope, is suited to study reactions at interfaces relevant to electrochemical processes. Specifically, with a transmission electron microscopy (TEM) a broad set of techniques (high-resolution imaging, electron diffraction and spectroscopy, etc.) can be used to characterize a reaction.
The process of splitting water into its constituents (hydrogen and oxygen) when an electrical current is passed through it has broad technological implications in devices that use hydrogen-based energy storage strategies. Here we describe an experimental setup to induce and observe water splitting within a TEM. Specifically, we correlate TEM images of gas bubble formation at a biased metal electrode immersed in an electrolyte (phosphate buffer solution) with the corresponding voltammetry analysis. We provide details of the in-situ TEM sample holder, microfabricated electrochemistry cell chips, basic circuitry, and imaging conditions.
We highlight the advantage of using in-situ TEM to study this solid-liquid reaction, by showing that it is possible to observe with nanometer resolution where bubbles are originated, their size and shape, and how they travel away from the active electrode; correlating this data with chemical states dictated by the potential of the active electrode. Finally, we discuss the electron beam effects expected in this type of experiments [3].
8:00 PM - ES04.19.14
High-Surface-Area Electrodes for Enhanced Scrap Metal Batteries
Michael Kitcher 1 , Alexandra Sourakov 1 , Jae Kim 1 , De Chen 1 , Matthew Coupin 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractAddressing sustainability and cost concerns regarding prevailing battery technologies, Muralidharan et al. demonstrated the first fully-functional cell battery consisting of oxidized scrap brass and steel with KOH as the electrolyte, thus inspiring this study. We aimed to advance the performance of this battery system through pre-oxidation processing of the electrodes to maximize oxide roughness and minimize unwanted alloy components. Replication of the results in the Pint’s group was considerably successful, with SEM and EDXS data confirming the presence of oxide layers on both electrodes post-anodization (via both galvanostatic and cyclic voltammetric methods). Additionally, cyclic voltammetry and stability curves were generally similar in the case of brass and significantly consistent for the steel electrodes. In the case of brass, Raman spectroscopy tests confirmed the presence of multiple copper oxides and hydroxides reported by Muralidharan et al. Dezincification was shown to facilitate consistent oxide nanostructuring and reduced the surface concentration of unwanted zinc oxides, while sandblasting also led to increased oxide surface area. Improvements in electrochemical properties were observed in both cases, with assembled batteries these electrodes exhibited an open circuit voltage of 0.6 V, energy densities of up to 8.2 Wh/kg and 94.8% cycling stability after 1000 cycles. Disparities between our results and that of Muralidharan et al. were observed, including the absence or non-uniformity of oxide nanostructuring in both electrodes and unusually consistent negativity of the open circuit potential of the brass electrode. Moreover, pre-anodization processes increased the propensity for residue-induced side reactions which had deleterious effects on electrode structure and electrochemical properties. Future work should aim at more complete experimental replication of the seminal results reported, further characterization - as well as control - of oxide microstructure and chemistry, and the effective incorporation of dezincification and sandblasting prior to electrode anodization.
8:00 PM - ES04.19.15
Effect of Composite Gel Electrolytes for the Performance of Solid State Super Capacitors
Tristan Skinner 1 , Curtis White 1 , Devonte Banner 1 , Larry Brown 1 , Sangram Pradhan 1 , Messaoud Bahoura 1
1 , Norfolk State University, Norfolk, Virginia, United States
Show AbstractAs technology advances devices are getting smaller and smaller with more power needed and energy being used. Super-capacitors are being investigated to replace conventional batteries in the future because of the energy conscious direction the world is heading towards. Super-capacitors have lower energy consumption but higher power distribution than conventional batteries which makes them better for the direction the world wants to take with its energy consumption. MnO2 has a high theoretical specific capacitance but can it is hard to achieve. In this case, a conductive polymer has been coupled with MnO2 to improve capacitance and conductivity. The need for flexibility in the super-capacitor is increasing, so PET/ITO was used as a substrate for the device. We report on the fabrication of a fully functioning flexible super-capacitor, while observing the electrical characteristics of various different polyvinyl alcohol based solid state gel electrolytes, such as polyvinyl alcohol only, polyvinyl alcohol with phosphoric acid, and polyvinyl alcohol with phosphoric acid doped with zirconium oxide. The different gel electrolytes are being studied to compare the variation of characteristics, such as power density, energy density, and capacitance. The MnO2 and Polypyrrole layers are deposited using Electrochemical depositing method. Topography studies have been conducted by the use of Atomic Force Microscopy, Scanning Electron Microscope, and Profilometer. Specific Capacitance and current density are also measured for the super capacitor device using cyclic voltammetry. We anticipated that the different gel electrolytes would result in different electrical properties that would lead to a wider range of application.
This work is supported by the NSF-CREST Grant number HRD 1036494 and NSF-CREST Grant number HRD 1547771.
8:00 PM - ES04.19.17
Comparison Study of In-Plane and Out-of-Plane Structured Multilayer Graphene Supercapacitors in Terms of Volumetric Performance
Jungjoon Yoo 1 , Yong Il Kim 1 , Chan-Woo Lee 1 , Jae-ha Myung 1 , Hana Yoon 1 , Jeonghun Baek 1 , Jong-Huy Kim 1
1 , Korea Inst of Energy Research, Daejeon Korea (the Republic of)
Show AbstractA graphene electrode with a novel in-plane structure is proposed and successfully adopted for use in supercapacitor applications. The in-plane structure allows the electrolyte ions to interact with all of the graphene layers in the electrode, thereby maximizing the utilization of the electrochemical surface area. This novel structure contrasts with the conventional out-of-plane stacked structure for such supercapacitors. We herein compare the volumetric capacitances of in-plane and out-of-plane structured devices with reduced multi-layer graphene oxide films as electrodes. The in-plane structured device exhibits a 2.5-times higher capacitance than the out-of-plane structured devices. Therefore, this study demonstrates the potential of in-plane structured supercapacitors with high volumetric performances as ultra-small energy storage devices.
8:00 PM - ES04.19.18
In Situ SEM Observation of the Amorphous Si Anode on LiPON Electrolyte During Lithiation and Delithiation
Hiroki Iwasaki 1 , Takayuki Yamamoto 1 , Munekazu Motoyama 1 , Yasutoshi Iriyama 1
1 Engineering, Nagoya University, Nagoya Japan
Show AbstractLithium-ion batteries (LIBs) have widely been used for many portable devices and electric vehicles. However, they use flammable organic solvents posing a danger of ignition at high temperatures. Hence, all-solid-state-lithium batteries (SSLBs) using an oxide solid electrolyte have attracted significant attention because it is nonflammable and stable against the air. Lithium metal has often been considered as a candidate for the negative electrode material of SSLB. However, the growth of Li dendrites through the grain boundaries of solid-state electrolyte and low Coulombic efficiency have been reported as serious problems for the applications by many authors.
Si has low charge/discharge potentials and a greater theoretical capacity (4200 mAh g-1) than other alloy metals such as Sn. Hence, it is also expected as a negative electrode material for the next generation battery [1]. However, a large volume expansion up to 400% occurs during the lithiation. This volume change leads to significant cracking and electrical isolation of Si anode [2].
In order to apply the Si anode for SSLB, it is important to prevent the cracking of Si anode [3]. This study reports in-situ scanning electron microscope (SEM) observations on how thin-film Si anode initiates cracking during lithiation and delithiation on LiPON electrolyte. We fabricate amorphous Si films on LiPON electrolyte by RF magnetron sputtering at room temperature. Although crystalline Si films can be fabricated at high temperature processes, such high temperature annealing are not favorable for LiPON. Charge/discharge cycles can be performed with Si films with thicknesses of 300 nm whereas those with thicknesses of 1000 nm quickly crack during the first cycle. These results can be understood by the Griffith-Irwin model that a crack continues to extend if the effect of released strain energy exceeds the surface energy increment. We also simulate stress distributions in Si films to consider the cracking mechanism.
[1] Sila Nanotechnologies Inc., http://www.silanano.com
[2] J. Li et al., J. Electrochem. Soc., 158, 689 (2011).
[3] J. W. Wang et al., Nano Lett., 13, 709 (2013).
8:00 PM - ES04.19.19
Systematic Expansion of Operating Voltage Window for Flexible Solid-State Super Capacitor Applications
Curtis White 1 , Tristan Skinner 1 , Kevin Santiago 1 , Devonte Banner 1 , Larry Brown 1 , Sangram Pradhan 1 , Messaoud Bahoura 1
1 , Norfolk State University, Norfolk, Virginia, United States
Show Abstract
The viable problem of flexible solid-state devices has been low voltage operation. This issue has been troublesome when it comes to super capacitor applications in particular due to the effect of the operation voltage on the energy density and performance. Super capacitors have exceptional specific capacitance beyond regular capacitors and extremely faster charge and discharge times than that of rechargeable batteries. This research was designed to make a systematic expansion of the operating window for flexible super capacitors by utilizing electrochemical deposition. MnO2 as well as polypyrrole were deposited electrochemically to a PET/ITO substrate. The MnO2 was deposited utilizing 1V and Polypyrrole by using 0.8V, respectively, making two distinct conformal layers. The solid state super capacitor shows very excellent flexiblility and stability and operates at higher voltage window of up to 2.5V as aresults the energy density of the supercapacitor increase multiple times.
This work is supported by the NSF-CREST Grant number HRD 1036494 and NSF-CREST Grant number HRD 1547771.
8:00 PM - ES04.19.20
Bulk vs Surface Charge Storage in Rare Earth Oxides
Aadithya Jeyaranjan 1 , Tamil Sakthivel 1 , Sudipta Seal 1
1 , University of Central Florida, Orlando, Florida, United States
Show AbstractIn recent years there has been a rapid surge in the number of microelectromechanical systems (MEMS) produced for a variety of sensing and actuating purpose. Electric energy storage devices (EEDs), that power these systems have often bottlenecked their progress of MEMS as these systems require low-cost EEDs with high energy and power densities in compact form factor. Pseudocapacitors are a class of supercapacitors that store charges by fast redox reactions. The very high cycle life and high power densities of pseudocapacitors make them a good fit to power MEMS. Due to their advantages, pseudocapacitors can not only be used as standalone EEDs but also be used in combination with batteries and energy harvesters.
There are a number of problems with currently used pseudocapacitor active material such as high cost, toxicity and phase change, that causes mechanical strain and failure. These drawbacks prevent the large-scale commercialization of pseudocapacitors. Overcoming these problems have been the basis to find new pseudocapacitive materials. Cerium oxide is a ceramic rare-earth oxide that has a low cost, non-toxic and environment friendly nature. The ability to reversibly change oxidation states at very low potential without any phase change has contributed to its increasing popularity in being used as a supercapacitor material.
The size and spatial constraints of the MEMS allows for only very small EEDs with lesser amounts of active energy storage material. Micro-supercapacitors with nano-sized active materials provides a solution for such spatial constraints. Thus, it is important to optimize the active material for maximum charge storage. Hereof, the effect of morphology on charge storage and the surface and bulk charge storage contribution of Cerium oxide nanoparticles have been studied using three different morphologies- nanorod (CNR), nanoparticles (CNP) and nanocubes (CNC).
The three different morphologies were obtained through a one-step hydrothermal synthesis by varying the temperature and concentration of the precursors. XRD, XPS, TEM and BET analysis were used for physical and chemical characterization of the different nanostructures.The electrochemical properties of the three different nanostructures were evaluated using cyclic voltammetry, continuous cyclic voltammetry, chronopotentiometry and impedance spectroscopy. The results from electrochemical studies indicate that CNR has a higher charge storage than other morphologies, due its surface area and rough texture. The surface and bulk charge storage contribution of the three morphologies were estimated by kinetics studies. This study shows that morphology clearly has an effect on charge storage and engineering the morphology could lead to supercapacitors with higher charge storage and last longer cycles.
8:00 PM - ES04.19.21
Using Metal Oxide Thin Films for Energy Storage Applications
Madhu Gaire 1 , Sijun Luo 1 , Binod Subedi 1 , Douglas Chrisey 1
1 Physics and Engineering Physics, Tulane University, New Orleans, Louisiana, United States
Show AbstractTo fulfil ever-growing energy needs research should be focused on energy storage devices with higher capacity and with low manufacturing cost. To meet this requirement, different devices, including batteries, capacitors, and supercapacitors have been used. Among them, supercapacitors are the ones that attract researcher’s attention due to their high energy density (compared with conventional capacitors), higher power density (compared with batteries), and long life cycle. Oxides of transition metals, including Ru, Mn, Fe, Co, V, etc. have been used as supercapacitor electrodes because they possess high pseudocapacitance and provide stability in the electrochemical system. In our research, we have used oxide films of Fe and Co. The precursor solutions used in our work are transition metal acetylacetonate dissolved in acetone. For the preparation of the samples, the precursor solution is spray coated on fused silica substrate and then photonically processed with a PulseForge 1300, an instrument which uses pulse light from a Xenon flash lamp to cure the sample. We characterized our films using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Raman Spectroscopy while cyclic voltammetry will be used to study the electrochemical properties. Samples are cured first with two pulses with fluence ~7.5 J/cm2.To study the characteristics of the samples after a different number of pulses, we have also prepared samples processed by 25 and 50 consequent pulses. In the case of FeOx samples, different forms of oxides are formed depending on the energy and number of pulses used. Keeping this in mind, we plan to synthesize samples with different thicknesses (this will be controlled by spray-coating duration), and with different fluence values. On the other hand, we have done preliminary measurements with cobalt oxide (Co3O4) thin film on Ti-Si substrate as well. Our hypothesis is that by using cobalt oxide films as a cathode and iron oxide film as an anode, we can fabricate an energy storing device with very good performance. Finally, what we can conclude is that with the ability to process the sample within a matter of seconds (by using PulseForge), large scale production of such devices is possible at very low cost compared to traditional physical and chemical deposition processes.
8:00 PM - ES04.19.22
Kinetics of Multivalent-Ion Intercalation into Two-Dimensional Vanadium Carbide MXene
Armin Vahid Mohammadi 1 , Majid Beidaghi 1
1 , Auburn University, Auburn, Alabama, United States
Show AbstractRapid growth in the development of portable electronic devices and electric vehicles (EVs) has significantly increased the demand for reliable and safe rechargeable batteries. Currently, Li-ion batteries are the dominant battery technology for portable electronics and EVs. However, limited lithium resources, their high cost, and safety issues have led to extensive research on the development of rechargeable batteries beyond Li-ion. Among various battery chemistries, multivalent-ion batteries based on divalent (Mg2+, Ca2+, Zn2+) or trivalent (Al3+) ions are promising candidates for future energy storage devices. One of the greatest challenges in the development of batteries based on multivalent ions is the sluggish transport of these ions in conventional intercalation materials used in Li-ion batteries. Therefore, the search for cathode materials for these batteries is focused on the materials with open structures or modifying the structure of conventional cathodes to decrease their interactions with intercalating multivalent ions. Herein, we present our results on the kinetics of multivalent ion intercalation into two-dimensional vanadium carbide (V2C) MXene. With a general formula of Mn+1Xn (n=1,2, and 3, M is a transition metal, and X is carbon and/or nitrogen), MXenes are a family of 2D transition metal carbides and/or carbonitrides that are produced by selective removal of the A layer elements (i.e. Al) from MAX phases (i.e. V2AlC), a large group of layered ternary carbides, nitrides, and carbonitrides. Through various electroanalytical and spectroscopic techniques, we have shed light on the intercalation mechanism and kinetics of intercalation of multivalent ions, including Mg2+ and Al3+, into MXene structures. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were used to study the structural evolution of V2C cathode during ion intercalation. X-ray photoelectron spectroscopy (XPS), as well as galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS), were used to understand the intercalation mechanism and type of intercalating ionic species in various electrolytes. Our results will provide a fundamental understanding of multivalent ion intercalation into MXene family of materials.
Keywords: 2D, Transition Metal Carbides, MXenes, Aluminum battery
8:00 PM - ES04.19.23
Study on Hydrothermal Synthesis of Polyanion Type Electrode Materials for Sodium-Ion Batteries
Masaki Okada 1
1 , Tosoh Corp, Shunan Japan
Show AbstractKen-ichi Takahashi1, Masaki Okada2, Shyun-ya Takahara2
1, Sagami Chemical Research Institute, Kanagawam, Japan, ,2, TOSOH Corporation, Tokyo, Japan
Sodium ion batteries are very attractive and promising for large scale electric power storage system because of abundant for sodium source, cost effective and long lasting. Here, we present character of hydrothermally synthesized Sodium Carbonophosphates Na3MPO4CO3(M=Fe, Mn) and its fluoride derivative as cathode material for sodium ion batteries. It was suggested that the hydrothermally synthesized Na3FePO4CO3 could react two electrons from the result of the charge-discharge cycling test. The analytical results of Na in the charged state and the discharged state using EPMA (Electron Probe Micro Analyzer) analysis also suggested a two electron reaction and the possibility that both Fe2 +/Fe3 + and Fe3 +/Fe4 + are electrochemically active was shown. In the fluoride derivative of Na3FePO4CO3, a potential plateau appeared at the discharge, suggesting the possibility of conversion reaction. In the viewpoint of the crystal structure and particle structure, capacity and cycle ability will be discussed.
8:00 PM - ES04.19.24
Fabrication of Flexible and High Performance of Graphene Quantum Dot-Polypyrrole (GQD-PPy) Nanocomposites for Hybrid Supercapacitor Electrodes
Ankarao Kalluri 1 , Devon Leighton 1 , Isaac Macwan 1 , Prabir Patra 1 2
1 Biomedical Engineering, University of Bridgeport, Bridgeport, Connecticut, United States, 2 Mechanical Engineering, University of Bridgeport, Bridgeport, Connecticut, United States
Show AbstractHybrid supercapacitors have gained significant attention and interest in energy storage field due to the progress in hybrid electric vehicles, space and military applications, moreover, it’s superior properties of high-power density and energy density, long cycle life, low cost, fast charging and slow discharging process and easy fabrication. Supercapacitors can achieve significant specific capacitance due to two charge storage mechanisms; the electrical double layer capacitance (EDLC), mainly due to high specific surface area, which can be maximized by using nanoparticles, such as graphene quantum dots (GQDs) and another one pseudo-capacitance can be maximized by the redox reaction of electrically conductive polymer like polypyrrole (PPy). Cyclic voltammetry (CV) was used for in situ polymerization of pyrrole and integration of GQDs to fabricate GQD-PPy free-standing films. This fabricate nanocomposite of 0.1% GQD-PPy with 100 cyles showing maximum specific supercapacitance of 465 F/g with ultrahigh energy and power density of 65.9 W h/Kg and 589 W/kg respectively. Furthermore, electrochemical properties analyzed by using cyclic voltammetry (CV), impedance spectroscopy (EIS) and interface evolution characterized by using electron microscopy (SEM, TEM) and X-ray diffraction studies (XRD). This PPy chains are evenly distributed and intercalated with GQDs and It was determined that the electrical conductivity is increased due to the pi-pi stacking between the GQDs and the PPy aromatic rings. A nanofibrous polycaprolactone (PCL) membrane was fabricated through electrospinning and effectively used as a separator in the supercapacitor. Four supercapacitors were assembling in series to demonstrate the device performance by lighting a 2.2 V LED light.
8:00 PM - ES04.19.25
Sputter-Deposited Lithium Niobite Thin-Film Electrode for Lithium-Ion Batteries
Dong Lee 1 , Joshua Shank 2 , William Doolittle 2 , Gleb Yushin 1 , Faisal Alamgir 1
1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractLithium-ion batteries have been broadly favored as one of the best energy storage system which has various classes of electrode materials being studied to satisfy the need for improved electrochemical performance. As a similar class to titanium-based oxides, niobium-based oxides continue to be considered as promising electrode materials with multiple pairs of Nb redox couples which can deliver more capacity than Ti-based oxides depending on their phase and charge-discharge condition. Among several phases of niobium oxides, lithium niobite (LiNbO2) has attracted scientific attention as a mixed ion-electron conductor proposing its use for the optical application as well as memristor and superconductor. Nevertheless, the research on lithium niobites as energy storage materials for lithium-ion batteries still lacks.
By sputter deposition, we fabricated one micron thick lithium niobite membrane for thin film electrodes in lithium-ion batteries. Material characterization using XRD and XPS with consecutive etching confirmed the unique (101)-oriented crystalline arrangement of as-synthesized lithium niobite and elucidated its initial lithium deficiency. As thin film electrode, lithium niobite deposition exhibited high capacity utilization and its stable retention as well as remarkable high-rate performance under the conducting agent- and binder-free condition. Over 400 cycles of charge-discharge at 56 mA/g (ca. C/4), lithium niobite thin film maintained 75 – 80% of capacity utilization based on its theoretical specific capacity (203 mAh/g) and, importantly, volumetric one (1124 mAh/cm3) as well as ~100% of coulombic efficiency over whole cycles. In addition to stable long-term cyclability, it also provided 15 mAh/g of discharge capacity even at 14 A/g of extremely high current density (ca. 70C) and demonstrated a full recovery of capacity at the following moderate rate. Ex-situ XRD revealed the unit parameter change originated from the insertion and desertion of lithium cations occupying the octahedral sites between (NbO2)n- layers of edge-shared NbO6 trigonal prisms. No phase evolution or extinction during cycling implies that the major capacity contribution of lithium niobite comes from the single-phase intercalation reactions, which was supported by voltage profiles as well. Post-mortem analysis using XPS confirmed the change on Nb’s oxidation status between Nb3.5+ and Nb2.5+ during charge-discharge, which indicates that the modulation of Li content at charging is limited by 0.5 (Li0.5NbO2). Combined with three different discharge behaviors shown in differential capacity curves, in-depth XPS analysis presented the evidence of minor capacity contribution from the conversion reaction of lithium niobites at low voltage (< 0.5 V).
8:00 PM - ES04.19.26
Freestanding and Porous Films for Energy Storage
Yang Yang 1 , Kyle Marcus 1
1 , University of Central Florida, Orlando, Florida, United States
Show AbstractFreestanding and porous films were rationally designed to serve as binder-free electrodes for renewable energy storage. A facile nanomanufacturing process was developed to fabricate these thin-film electrodes with nanoporous structure and controllable composition. These porous films can be directly used as flexible and additive-free electrodes for supercapacitor and rechargeable battery applications without using binders, current collector and other additives. Significantly enhanced electrochemical performances were therefore achieved due to the unique merits of these NPL: i) highly porous structure considerably increase the electrode/electrolyte interface, which facilitates the electrochemical reaction; ii) residual metal-filaments in the film form an interconnected conductive framework, which drastically improves the flexibility and conductivity of the electrode.
8:00 PM - ES04.19.27
Effect of Decreasing Cobalt Content on the Electrochemical Properties and Structural Stability ofLi1-xNiyCozAl0.05O2 Type Cathode Materials
Kamalika Ghatak 1 , Swastik Basu 3 , Hemant Kumar 2 , Siva Nadimpalli 1 , Dibakar Datta 1
1 , New Jersey Institute of Technology, Newark, New Jersey, United States, 3 , Rensselaer Polytechnic Institute, Troy, New York, United States, 2 , University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractIn Lithium ion batteries (LIBs), proper design of cathode materials influences its intercalation behavior, overall cost, structural stability, and its impact on environment.1-4 At present, the most common type of cathode materials,5 NCA (Li1-xNi0.80Co0.15Al0.05O2), has very high cobalt concentration. Since cobalt is toxic and expensive, the existing design of cathode materials is not cost-effective, and environmentally benign. However, these immensely important issues have not yet been properly addressed yet. Therefore, we have performed density functional theory (DFT) calculations to investigate three types of NCA cathode materials NCACo=0.15 (Li1−xNi0.80Co0.15Al0.50O2), NCACo=0.10 (Li1−xNi0.85Co0.10Al0.50O2), NCACo=0.05 (Li1−xNi0.90Co0.05Al0.50O2 ), where x = 0 to 1. Our results show that even if the cobalt concentration is significantly decreased from NCACo=0.15 to NCACo=0.05, variation in intercalation potential and specific capacity is not significant. For example, in case of 50% Li concentration, voltage drop is ~0.12V while change in specific capacity is negligible. Moreover, decrease in cobalt concentration doesn’t influence the structural stability. We have also explored the influence of sodium doping on the electrochemical and structural properties of these three structures. Our results provide deep insight into the design of cathode materials with reduced cobalt concentration and thus produce environmentally benign, low-cost cathode materials. In order to account for the possible phase change of the cathode material during lithiation/de-lithiation, we have also performed the room temperature ab-initio molecular dynamics simulation of each of the moieties.
1. Tollefson, J. Charging up the Future. Nature 2008, 456 (7221), 436.
2. Dahn, J.; Fuller, E.; Obrovac, M.; Von Sacken, U. Thermal Stability of Lixcoo2, Lixnio2 and Λ-Mno2 and Consequences for the Safety of Li-Ion Cells. Solid State Ionics 1994, 69 (3-4), 265-270.
3. Orendorff, C. J.; Doughty, D. H. Lithium Ion Battery Safety. The Electrochemical Society Interface 2012, 21 (2), 35-35.
4. Etacheri, V.; Marom, R.; Elazari, R.; Salitra, G.; Aurbach, D. Challenges in the Development of Advanced Li-Ion Batteries: A Review. Energy & Environmental Science 2011, 4 (9), 3243-3262.
5. Nitta, N.; Wu, F.; Lee, J. T.; Yushin, G. Li-Ion Battery Materials: Present and Future. Materials today 2015, 18 (5), 252-264.
8:00 PM - ES04.19.28
Anomalous Ionic Conductivity Behavior of Fast Oxygen Conducting Electrolytes Due to an Underlying Nanoscale Percolation Network
Methary Jaipal 1 , Abhijit Chatterjee 1
1 , Indian Institute of Technology Bombay, Mumbai India
Show Abstract
Fast oxygen conducting solid state electrolytes are frequently used in solid oxide fuel cells and other electrochemical devices. Many of these electrolytes demonstrate a surprising ionic conductivity behavior wherein the ionic conductivity show a maximum value at an optimal dopant concentration. Using yttria-stabilized zirconia (YSZ) as a test electrolyte material we probe the effect of percolation network structure in YSZ on the ionic conducitivity. Although crucial to its ionic conductivity is a nanoscale percolation network formed due to the O2- ion-blocking nature of Y3+ ions in YSZ, the mesoscopic scale features of the network and their effect on ionic conduction remains poorly understood. New insights into the topology, composition and O2- ion carrying capacity of percolation network in YSZ are gained using kinetic Monte Carlo (KMC) simulations. Our study reveals that depending on the Y2O3 content nearly 20-50% of the YSZ structure does not participate in ionic conduction. The remaining material can be categorized into four sub-networks with O2- movement being facile in some sub-networks and sluggish in others. O2- ion carrying capacity depends on the vacancy hopping rates for cation arrangements within the network and a site occupation term. Despite the presence of diverse cation arrangements within a sub-network, an interplay between the multimodal site occupation terms and rates yields a characteristic temperature-dependent migration rate for the sub-network. Ionic conduction in YSZ can be essentially understood in terms of two percolation sub-networks. A major finding is that dopant composition- and temperature-dependence of ionic conductivity can be linked to a mesoscale structural descriptor for the sub-network, namely, the fastest/shortest path length. This finding bridges the mesoscale gap in our understanding of ionic conduction in solid electrolytes.
8:00 PM - ES04.19.29
Biotemplating Synthesisof One-, Two- and Three-Dimensional Carbon Related Nanostructures for High Performance Energy Storage
Xinyong Tao 1 , Hui Huang 1 , Wenkui Zhang 1 , Yongping Gan 1 , Yang Xia 1 , Chu Liang 1 , Jun Zhang 1
1 , Zhejiang University of Technology, Hangzhou China
Show AbstractIt is no doubt that nature is the greatest teacher in the world. It has already provided us one-, two-, and three-dimensional elaborate architectures with multiplesizes ranging from nanoscale to macroscale. More importantly, biological resources are inexpensive,abundant, and renewable. Therefore, scientists and engineers are inspired by nature to develop biotemplating techniques. Our recent researchesdemonstrated that the rational utilization of biotemplating strategy can realize high performance of energy storage/conversion electrode materials.
One-dimensional nanostructure:TaC/TiC/NbC/B4C nanowires were synthesized via carbothermal method using bamboo/cotton/plants fibers as both the carbon source and the temple. And the obtained nanowires exhibited remarkable energy storage/energy transfer performance as promising electrode/matrix materials for supercapators, lithium-ion batteries, methanol fuel cells, and position/force peapod sensors.
Two-dimensional nanostructure: Fish scale-like carbon nanotile was synthesized by a facile carbonization and grind procedure using kapok fibers as green carbon source. And the obtained carbon nanotile exhibited high and stable capacity when used as the host of sulfur for Li-S batteries. On the basis of previous work, we synthesized various nonconductive metal-oxide nanoparticle decorated carbon flakes.Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption.
Three-dimensional nanostructure: Hollow porous MnO/C microsphere, hierarchically porous NiO/C, Sn@C and hierarchical LiFePO4/C were synthesized using microalgae/lotus pollen grain/spirulina as the both the carbon source and the temple. And the obtained composites exhibited high reversible specific capacity, excellent cycling stability and enhanced rate performance for lithium-ion batteries.
References:
1. Tao, X. Y.*; Sheng, O. W.; Cui. Y.* et al., Nano Letters, 2017, DOI: 10.1021/acs.nanolett.7b00221.
2. Tao, X. Y.; Cui, Y.* et al., Nature Communications, 2016, 7, 11203.
3. Tao, X. Y.; Zhang, W. K.*; Cui, Y.* et al., Nano Letters,2014, 14, 5288-5294.
4. Luo, J. M.; Tao, X. Y.* et al., ACS Nano, 2017, 11, 2459-2469.
5. Luo, J. M.; Tao, X. Y.*; Zhang, W. K. et al., ACS Nano, 2016, 10, 2491-2499.
6. Tao, X. Y.; Zhang, W. K.; Dong, L. X.*; Li, X. D.* et al., Nano Letters, 2015, 15, 7281-7287.
7. Sheng, O. W.; Zhang, W. K.; Tao, X. Y.* et al., Journal of Materials Chemistry A, 2017, DOI: 10.1039/C7TA03699J.
8. Jin, C. B.; Sheng, O. W.; Zhang, W. K.; Tao, X. Y.* et al., Nano Energy, 2017, 37, 177-186.
9. Jin, C. B.; Zhang, W. K.; Tao, X. Y.* et al., Journal of Materials Chemistry A, 2017, 5, 632-640.
10. Tao, X. Y.; Zhang, W. K.*; Gan, Y. P.* et al., Journal of Materials Chemistry A, 2014, 2, 2290-2296.
11. Tao, X. Y.; Zhang, W. K.* et al., ACSApplied Materials & Interfaces, 2014, 6, 3696-3702.
12. Tao, X. Y.*; Zhang, W. K.; Dong, L. X.*; Li, X. D.* et al., Advanced Energy Materials, 2011, 1, 534-539.
8:00 PM - ES04.19.30
Influence of Electrochemical and Thermal Stress on the Aluminum Environment for Nickel Rich Layered Oxide Cathodes
Zachary Lebens-Higgins 1 , Shawn Sallis 2 , Nicholas Faenza 3 , Fadwa Badway 3 , Nathalie Pereira 3 , David Halat 4 , Pinaki Mukherjee 5 , Frederic Cosandey 5 , Clare Grey 4 , Glenn Amatucci 3 , Louis Piper 1 2
1 Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York, United States, 2 Materials Science and Engineering, Binghamton University, State University of New York, Binghamton, New York, United States, 3 Energy Storage Research Group, Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, North Brunswick, New Jersey, United States, 4 Department of Chemistry, University of Cambridge, Cambridge United Kingdom, 5 Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States
Show AbstractFor layered oxide cathodes, there continues to be a large gap between practical and theoretical capacities because of poor performance at high voltages (≥4.3). This poor performance is primarily due to reactions at the cathode electrolyte interface (CEI) that result in surface oxygen loss and subsequent surface phase transformations. For example, a recent study correlated impedance growth with surface phase transformations when Li1-xNi0.8Co0.15Al0.05O2 electrodes are held at ≥4.5V. [1] Aluminum oxide coating layers have gained continued interest due to their ability to increase high voltage performance. Improved performance is often associated with the role of aluminum as an HF scavenger to suppress degradation of the cathode. [2] While aluminum doping can similarly result in improvements in thermal stability and electrochemical performance [3], there has been limited work on the influence of aluminum on surface phase transformations and cathode electrolyte reactions at the CEI.
Here, we report on our surface studies of aluminum doped layered oxide systems to examine the influence of electrochemical and thermal stress on the surface aluminum environment. Using hard x-ray photoelectron spectroscopy in conjunction with x-ray absorption spectroscopy, and including complementary 19F and 27Al solid state nuclear magnetic resonance spectroscopy, we investigate how the aluminum surface environment changes alongside electrolyte decomposition and surface phase transformations. By comparing Li1-xNi0.8Co1-yAlyO2 systems with different levels of aluminum doping, we correlate the CEI layer composition and thickness with aluminum content. Our work provides additional insight into the role of aluminum at the surface of layered oxide cathodes at high voltage.
This work was supported as part of NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583
[1] S. Sallis et al., App. Phys. Lett. 108 263902 (2016)
[2] Z. Chen et al., J. Mater. Chem. 20, 7606 (2010)
[3] J. Xu et al. J. Mater. Chem. A 5 874 (2017)
8:00 PM - ES04.19.31
A New Approach to Synthesis Micro-Sized Silicon Anode Materials for Lithium-Ion Batteries
Haiping Jia 1 , Junhua Song 1 , Xiaolin Li 1 , Ji-Guang Zhang 1
1 , Pacific Northwest National Laboratory, Richland, Washington, United States
Show AbstractSilicon has been extensively studied as a high-capacity anode for next-generation high-energy Li-ion batteries (LIBs). It exhibits a very high theoretical specific capacity of 4,200 mAh g-1 and a relatively low lithiation potential of 0.2 V vs. Li/Li+, compared to the conventional carbonaceous anode materials (372 mAh g-1), which cannot meet the growing demand for higher specific energy (Wh kg-1) and energy density (Wh L-1) of LIBs. However, fast capacity fade still greatly limits its practical application. A large volume change during lithiation and delithiation causes pulverization and subsequent loss of electrical contact, continuous consumption of electrolyte, repeated breaking/formation of the solid electrolyte interphase (SEI) and an increase in the overall resistance. There has been significant progress to understand and mitigate the capacity fade in Si-based anodes exploiting nanostructured electrodes, surface coatings, additives and novel binders. These advances have paved the way for practical application of Si-based anodes for Li-ion battery applications. However, most nanostructured Si materials have to be prepared by high-cost processes that are difficult to scale up. And the nanostructured Si still suffers the poor first- and later- cycle Coulombic efficiencies (CE). In this regard, increasing attention has been paid to use Si microparticles as a low-cost starting materials. The low temperature growth of conformal graphene cages on micron-sized silicon particles (SiMP) exhibit high CE, but the unavoidable pulverization of SiMP still leads to instability of this material during long term cycling.
Herein, we report a new and low cost approach to synthesis porous silicon with a size ranging from 500nm to 10µm. The as-prepared material demonstrates uniform mesopores and ~20 nm-sized Si crystallites. The fine primary particles can shorten the Li+ transport route, and avoid the pulverization of SiMP. The obtained porous silicon delivers a reversible capacity of 1900 mAh g-1 at 0.5C and 85% capacity can be retained after 100 cycles. The details of materials preparation, microscopic characterization, and electrochemical performance will be discussed in this presentation.
8:00 PM - ES04.19.32
Quantifying Oxygen Electro-Adsorption and Its Influence on Oxygen Evolution on IrO2(110) and RuO2(110)
Ding-Yuan Kuo 1 , Hanjong Paik 1 , Jocienne Nelson 2 , Jason Kawasaki 2 3 4 , Jan Kloppenburg 5 , Geoffroy Hautier 5 , Kyle Shen 2 3 , Darrell Schlom 1 3 , Jin Suntivich 1 3
1 Materials Science and Engineering, Cornell University, Ithaca, New York, United States, 2 Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States, 3 Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York, United States, 4 Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin, United States, 5 Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Louvain-la-Neuve Belgium
Show AbstractOxygen evolution reaction (OER) catalysis has enormous scientific and technological implications for electrochemical energy storage technologies. Surface oxygen adsorption plays a critical role in the OER catalysis; understanding the relationship between surface-oxygen interaction and OER is therefore key to unlocking the OER mechanism. We present our investigation on the role of surface-oxygen interaction in the OER on IrO2(110) and RuO2(110). We quantify the electro-adsorption energy of oxygen species (e.g. OHad and Oad) on IrO2(110) and RuO2(110) in a series of pH values. We find that pH affects the electro-adsorption of oxygen species. We use these electro-adsorption values to quantify how the electro-adsorption energy of oxygen species affects the OER using the thermodynamic limiting step concept. We will discuss whether the oxygen electro-adsorption energy can serve as a descriptor to the OER and how its experimental probe can aid in the future optimization of OER catalysts.
8:00 PM - ES04.19.33
Highly Efficient Protection by Atomic Layer Deposition/Molecular Layer Deposition for Lithium and Sodium Metal Anode
Yang Zhao 1 , Xueliang Sun 1
1 , Univ of Western Ontario, London, Ontario, Canada
Show AbstractLi metal anode is considered as the promising candidate for next generation Li-metal batteries. However, it is still a crucial problem of mossy or dendritic growth of Li occurs in the repetitive Li stripping/plating process with an unstable solid electrolyte interphase (SEI) layer, which may create short circuit risks, resulting in possible burning or explosion. Atomic layer deposition (ALD) can be one of the promising technique with excellent coverage and precise control over coating thickness to stabilize the SEI layer and longer the life time for Li metal anode [1]. Two different groups have demonstrated ultrathin ALD Al2O3 coating film as protective layer for metallic lithium with the prevention of corrosion and reduced dendrite growth [2]. As an analogy of ALD, molecular layer deposition (MLD) can be employed to produce polymeric thin films with many advantages such as tunable thermal stability, and improved mechanical properties [3]. Herein, we firstly demonstrate MLD alucone (Al-EG) coating as a protective layer for Li metal anode for improved stability and life time [4]. Alucone layer can stabilize the SEI film and further reduce dendrite growth, which leading to the better performances than Al2O3 coating.
Na-ion batteries and Na-metal batteries are expected to be used as large scale energy storage devices. Na metal anode show a high theoretical specific capacity of 1166 mAh g-1 and lowest electrochemical potential. However, similar problems including mossy and dendritic Na growth is one of the challenge for Na metal anode. Here, we demonstrated the successful application of the ALD Al2O3 protective coating on Na metal anode in ether based electrolyte to achieve long lifetime Na metal anode [5]. Furthermore, we firstly demonstrate the inorganic-organic coating MLD Alucone as coating layer for Na anode in carbonate based electrolyte with suppressed dendrite growth and enhanced electrochemical stability [6].
In conclusion, we demonstrate ultrathin ALD Al2O3 and MLD alucone protective coating layers for both Li and Na metal anode. The results show that the formation of mossy and dendrite-like Li/Na can be effectively suppressed and life time is significantly improved with protective layer. It is also worth to mention that we have first introduced a strong tool of Rutherford Backscattering Spectrometry (RBS) in the Li/Na protection area. It is believed that our design of ALD/MLD coating on Li/Na anode opens up new opportunities to the realization of next-generation high energy density Li/Na metal batteries.
[1] X. Meng, X. Sun, et al, Advanced materials, 2012, 24, 3589
[2] A. Kozen, M. Noked, et al, ACS Nano, 2015, 9, 5884; E. Kazyak, N. Dasgupta, et al,
Chemistry of Materials, 2015, 27, 6457.
[3] X. Li, X. Sun, et al, Nano Letters, 2016, 16, 3545; Y. Zhao, X. Sun et al, 2017, submitted
[4] Y. Zhao, X. Sun et al, 2017, submitted
[5] Y. Zhao, X. Sun, et al, Advanced materials, 2017, 29, 1606663
[6] Y. Zhao, X. Sun et al, 2017, submitted
8:00 PM - ES04.19.34
An O3-Type Layered Sodium Quaternary-Mixed Transition Metal Oxide with Promising Electrochemical Properties
Jae Chul Kim 1 , Deok-Hwang Kwon 2 , Shou-Hang Bo 1 , Haegyeom Kim 2 , Plousia Vassilaras 3 , Stephen Dacek 3 , Gerbrand Ceder 2
1 , Lawrence Berkeley National Lab, Berkeley, California, United States, 2 , University of California, Berkeley, California, United States, 3 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractWhen it comes to cost per energy, Na-ion batteries offers an opportunity to meet the increasing demand for affordable energy storage in large-scale. Unlike the Li system, the energy-dense Na layered oxides can make use of Fe, which is an attractive element due to its high potential and natural abundance. However, the charged state instability of the layered framework leads to poor reversibility, limiting the practical application of the material. To address this problem, we propose Ti4+ as a structural stabilizer and report a new Na quaternary-mixed transition metal oxide, NaTi0.25Fe0.25Co0.25Ni0.25O2. Synthesized by a solid-state reaction, the compound obtained is phase-pure with the O3-type layered structure. X-ray absorption spectroscopy reveals that transition metal oxidation states are Ti4+, Fe3+, Co3+, and Ni2+, suggesting that Ti remains electrochemically inert while others are redox-active. Our results highlight promising electrochemical performance of the material; 504 Wh kg-1 at C/20 and 200 Wh kg-1 at 30C at room temperature. Compared with the pristine O3 structure, we find that the structure is unchanged when fully discharged at 2 V, leading to respectable cyclability. Interestingly, the structural evolution in Na extraction, as observed by in situ XRD, differs from that in Na re-insertion processes. We will discuss the possible origin of this path-dependency of desodiated structures and its implication on electrochemical properties in this talk.
8:00 PM - ES04.19.36
Crosslinking Polyrotaxanes—Molecular Pulley Binder for Silicon Microparticle Anodes in Lithium-Ion Batteries
Sunghun Choi 1 , Tae-woo Kwon 1 , Ali Coskun 1 , Jang Wook Choi 1
1 , Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of)
Show AbstractThe demand for Lithium-ion batteries (LIBs) with high-energy density have increased due to the advent of smart devices and electric vehicles. Accordingly, silicon (Si) anodes have been spotlighted for their high specific capacity (>3000 mAh g-2). However, the Si anodes have suffered from poor cycle performance due to the drastic volume change of Si, which results in the pulverization of particles and unstable solid electrolyte interface (SEI) formation. Although strong adhesive binders have improved cycle retention of Si nanoparticle anodes, binders have yet to function properly with Si microparticle (SiMP) anodes.
In this presentation, I will introduce a novel polymeric binder for SiMP anodes, in which 5% of polyrotaxane (PR) is crosslinked with conventional polyacrylic acid (PAA) [1]. The PR consists of polyethylene glycol (PEG) threads interlocked to a-cyclodextrin (a-CD) rings. Surprisingly, due to the sliding motion of the a-CD ring, the PR was able to effectively reduce the stress exerted on the polymer network, as moving pulleys work in macro-scales. The binder film can be stretched up to 390% without breakage. Although SiMPs are pulverized during battery cycling due to their particle dimensions, the elasticity of the binder network allows even the pulverized Si particles to remain coalesced, originating from the ring sliding of polyrotaxanes. In half-cell measurements, the SiMP electrode based on the PR-PAA with a high areal capacity (2.67 mAh cm-2) has superior cycling performance of 91% retention after 150 cycles and high coulombic efficiencies, i.e., 91.22% for the initial cycle and an average value of 99.64% for the subsequent cycles. In addition, a full-cell pairing with LiNi0.8Co0.15Al0.05O2 (NCA) cathode maintained 98% of its initial capacity after 50 cycles with the commercial level of an areal capacity (2.88 mAh cm-2).
References
[1] S. Choi et al. “Highly elastic binders integrating polyrotaxanes for silicon microparticle anodes in lithium ion batteries” Science, in press.
8:00 PM - ES04.19.37
Fabrication of Silicon/CNT-Stuffed and Dumpling-Structured Carbon Microparticles Using Electrospraying and Their Application to Li-Ion Battery Electrodes
Jihyun Yoon 1 , Byoung-Sun Lee 2 , Ji ho Youk 3 , Woong-Ryeol Yu 1
1 Material Science and Engineering, Seoul National University, Seoul Korea (the Republic of), 2 Department of Nano Engineering, University of California, San Diego, California, United States, 3 Department of Applied Organic Materials Engineering, Inha University, Incheon Korea (the Republic of)
Show AbstractSilicon (Si) /carbon nanotubes (CNTs) /void-core /carbon-shell micro-particles were successfully manufactured using electrospraying process. Electrospraying is a simple and eco-friendly process for fabricating nano- and micro-particles; however, it has not attracted much attention as a fabrication method for dumpling-structured particles due to difficulties in controlling process parameters. In this study, Si/CNTs-stuffed/void carbon micro-particles in dumpling structure were successfully manufactured using a series of processes such as electrospraying, polydopamine coating, and carbonization. Silicon and CNTs embedding polymer particles were fabricated via electrospraying. The polymer particles were coated with polydopamine as a carbon source. To form voids and carbon shell, the coated particles were heat treated at proper temperature (773K) to decompose the sacrificial polymer (core) and carbonize the polydopamine coating to carbon shell. The carbon micro-particles were characterized using scanning electron microscopy and transmission electron microscopy, clearly demonstrating successful dumpling structure. The compositions were also characterized using energy dispersion spectroscopy, confirming Si and CNT and carbon in core and shell, respectively. The carbon shell of the micro-particles was nanometer thick and porous (ca. 50nm), offering a new material for a battery electrode.
The carbon micro-particles were used to prepare the negative electrode for Li-ion battery. The thin and porous carbon shell of the particles is expected to inhibit direct contacts between the electrolyte and the active material and to prevent the capacity fade and continuous formation of solid electrolyte interphases. The energy density of Si/CNTs-stuffed and dumpling-structured carbon microparticles was significantly increased, e.g., 95% larger than carbon-coated Si nanoparticle electrode. The initial efficiencies and capacity retention of a battery system employing Si/CNTs-stuffed carbon micro-particles increased (67.8% and 85.5% after 50 cycles, respectively), while the volume expansion ratio of the electrode was 26.5%. The sizes of the dumping-structured carbon micro-particles affected cycle stabilities, i.e., carbon micro-particles with a diameter of 2.5 micrometers showed 25% increased capacity retention than 10 micrometers at 100th cycle. For more promising results, an optimized morphology including material composition ratio is under investigation and will be presented at the conference.
8:00 PM - ES04.19.38
Growth of Pore-Embedded Graphitic Carbon Shell on Silicon for High Performance Lithium-Ion Battery Anode
Chul Ho Jung 1 , Seong-Hyeon Hong 1
1 Material Science, Seoul National University, Seoul Korea (the Republic of)
Show AbstractLithium-ion batteries have become one of the most promising energy-storage technologies, in particular for portable electronics. Recently, the emergence of electrical vehicles has driven the requirements for the research on Lithium-ion batteries in terms of the design and developments of materials exhibiting higher energy density with long term cyclability. To enhance the energy density, substituting anode materials from conventionally used graphite (372 mAh g-1) to silicon, which has capacity up to ten times (~3600 mAh g-1) has been realized promising. Unfortunately, a practical application of silicon is yet to become reality due to tremendous volume change during charge/discharge (>300%), which leads to severe issues, such as loss of electrical contact between electrode with current collector and consequent capacity degradation. Even though nano structuring has been conducted and proven to be effective, easy and scalable synthesis methods are crucial for practical applications. From a practical standpoint, the use of commercial silicon with carbon composite is a promising candidate. Unfortunately, carbon segregates as a result of mechanical stress during cycling, resulting in unreliable electrochemical performance. Since the brilliant design of carbon coating shell, which can buffer the volume change of silicon, enhances the electrical conductivity and avoids the carbon segregation, many researches have been conducted. However, most of the investigations have been carried out for amorphous carbon as a shell, which has several drawbacks, such as low electrical conductivity due to lack of long-range order and low mechanical strength resulting in fracture over repeated cycles.
Recently, metal-containing graphitic carbon has been prepared by Fe3+-dopamine complexation method to enhance the catalytic activity. By utilizing this experimental method, graphitic carbon could be directly grown on silicon without precedent metallic coating. However, this facile and robust approach for graphitic carbon formation has not been applied to silicon anode and its LIB performance. Along to the formation of graphitic carbon, pore is also formed inside a graphitic carbon at the final step of acid treatment procedure, which could also aid in electrochemical performance by enhancing the Li+ ion mobility and its effectiveness in buffering the volume change of silicon.
In this study, pore-embedded graphitic carbon coated Si are synthesized through Fe3+-mediated polymerization of dopamine and subsequent carbonization and acid treatment, and their electrochemical performance as an anode for LIBs is investigated, and compared with that of amorphous carbon coated Si. As-obtained Si electrode exhibits an excellent long term cycle performance, delivering a high capacity of 1056 mA h g-1 after 800 cycles at a high current density of 2000 mA g-1, which can be attributed to high electrical conductivity, ionic conductivity and mechanical strength of porous graphitic carbon.
8:00 PM - ES04.19.39
Homopolymer-Based Physical Ion Gels for Solid-State Electrochemical Devices
Kyunggook Cho 1 , Kyoung Hwan Seol 1 , Seungju Lee 1 , Kihyon Hong 2 , Keun Hyung Lee 1
1 Chemical Engineering, Inha University, Incheon Korea (the Republic of), 2 , KIMS, Changwon Korea (the Republic of)
Show AbstractIon gels that solidify room temperature ionic liquid using host polymer networks have attracted much attention because they possess excellent advantages of ionic liquids such as ionic mobility, specific capacitance, and chemical and electrochemical stabilities in a solid form. In this work, we have fabricated homopolymer-based physical ion gels based on aliphatic polyamides and an ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMI][TFSI]. The free-standing ion gels possess excellent material properties such as large ionic conductivity, high specific capacitance, and good thermal stability. These gel electrolytes were successfully implemented in two types of thin-film electrochemical devices: as high capacitance gate dielectrics in electrolyte-gated transistors and as electrolyte membranes in supercapacitors. Electrolyte-gated transistors were fabricated by using a poly(3-hexylthiophene) semiconductor, an ion gel gate dielectric, and a poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) gate electrode. The resulting electrolyte-gated transistors operated at low voltages below 1 V with high transconductance currents because of the high capacitance of the ion gels. All solid-state supercapacitor were fabricated by sandwiching an ion gel membrane by carbon nanotube-based composite electrodes. These supercapacitors operated at higher voltages than those with aqueous electrolytes and showed appropriate high capacitance. These results demonstrate that the aliphatic polyamide-based physical ion gels provide a convenient route to generate high performance solid polymer electrolytes for various solid-state electrochemical devices
8:00 PM - ES04.19.40
Hybrid Solid Electrolyte in Combination of Li7La3Zr2O12 Ceramic and Ionic Liquid for High Voltage Pseudo-Solid State Li-Ion Batteries
Hyun Woo Kim 1 , Youngsik Kim 1
1 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
Show AbstractConcerning the safety aspects the present Li-ion battery technologies are obligatory to use in high power applications viz., electric vehicles (EVs), hybrid electric vehicles (HEVs), and grid energy storage application. Because the liquid electrolytes containing organic carbonates are limited at 4.8 V and generates volatile gaseous species, leakage and flammable owing to thermal runaway.
To address these issues, several electrolytes based on solid phase Li-ion conducting materials such as polymer electrolytes and ceramic solid electrolytes have been investigated as an alternative electrolyte. The concept of Li-ion conducting in particularly ceramic solid electrolyte is most attractive direction due to high voltage stability, thermal stability, highly stable with lithium metal and also provide fast Li-ion transportation. Several types of solid electrolytes such as garnet Li5La3Ta2O12, Li1+xAlxGe2−x(PO4)3, Li1+xTi2−xAlx(PO4)3 and LiTi2-xZrx(PO4)3 etc., are investigated for all solid state Li-ion batteries. However, it is also suppressed by its critical issue of grain boundary resistance due to instable contact between solid-solid interfaces.
In the view of this, we designed a new type of hybrid solid electrolyte (HSE) combining 80wt% ceramic particles (Li7La3Zr2O12, hereafter LLZO) with 20wt% of a lithium salt (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) and an ionic liquid (N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, Py14TFSI) as a new candidate for Li-ion batteries. The garnet-type cubic phase LLZO material is superior candidate to be used as a ceramic electrolyte in the HSE due to its significant lithium ionic conductivity (> 10–4 S cm–1). Moreover, the garnet-type electrolyte has a thermal stability with lithium metal and good electrochemical stability (> 5 V). With the meriting aspects, the choice of ionic liquid can be intensive scientific interest to minimize the interfacial resistance of ceramic LLZO particles and solid electrodes coupled with wide potential window with respect to lithium metal electrode related to low melting point, low vapor pressure, non-flammability and good chemical and thermal stabilities.
The optimized HSE exhibited superior thermal stability (> 350 °C), an ionic conductivity of 0.4 × 10–3 S cm–1, and an impressive electrochemical stability of 5.5 V at a scan rate of 0.2 mV s–1. The fabricated cells delivered initial charge-discharge capacities of 140/130 mAh g–1 (Li/HSE/LiCoO2) with good capacity retention up to 150 cycles. Expanding the scope of the present investigation, the unique properties of the HSE were also expressed in a Swagelok-type bipolar (Li/HSE/LiCoO2-SS-Li/HSE/LiCoO2) high voltage (> 8 V) pseudo-solid-state LIB. From these results, it is clear that the electrochemical performance of this HSE is quite promising and it can be used for high voltage pseudo-solid-state LIBs.
8:00 PM - ES04.19.41
Silicon Anodes Incorporating Few-Layer Graphene (FLG) for Improved Cyclability in Li-Ion Batteries
Qianye Huang 1 , Melanie Loveridge 1 , Romeo Malik 1 , Ronny Genieser 1 , Rohit Bhagat 1
1 , University of Warwick, Coventry United Kingdom
Show AbstractSilicon remains a promising anode material for next generation lithium-ion batteries, despite the well-documented issues associated with it, namely fast capacity fade and volume expansion. Its abundance and high capacity (3579mAh/g: almost 10 times higher than the capacity of graphite) has made it the focus of high profile research for the last decade. However, the problems still facing Si-based battery commercialization are yet to be successfully overcome. Graphene has been shown to possess excellent electrical conductivity, a high surface area, and is considered promising to enhance the electrochemical performance of Si electrodes. Several studies have been conducted on hybrid silicon/graphene electrodes with long cyclability achieved. However, most of these studies either focused on nano-sized Si particles or used complicated chemical methods (such as electrophoretic deposition and chemical vapour deposition) to combine silicon and graphene, but this is considered impractical to progress to large-scale manufacture.
Silicon-Few Layer Graphene (Si-FLG) composite electrodes are investigated using a scalable electrode manufacturing method. The study demonstrates that the incorporation of FLG results in significant performance improvement in terms of cyclability, electrode resistance and diffusion properties. The diffusion impedance during Si phase changes, as well as the variation against cycle number, is elucidated through Staircase Potentio Electrochemical Impedance Spectroscopy (SPEIS): a more comprehensive and straightforward approach than previous state-of-charge (SoC) based diffusion studies. Additionally, further characterization on failure mechanisms including tensile testing, post-mortem X-ray computed & FIB-SEM 3D tomography analysis are conducted to give more evidence as to the benefits around electrode structural changes with the incorporation of FLG into Si electrodes.
8:00 PM - ES04.19.42
Classifying Sources of Heterogeneity in Porous, Composite Solid Oxide Fuel Cell Electrode Microstructures
William Epting 1 3 , Tim Hsu 2 , Rubayyat Mahbub 2 , Paul Salvador 2 , Paul Ohodnicki 1 , Harry Abernathy 1 4 , Gregory Hackett 1
1 National Energy Technology Laboratory, Department of Energy, Pittsburgh, Pennsylvania, United States, 3 , Oak Ridge Institute for Scientific Education, Oak Ridge, Tennessee, United States, 2 Department of Materials Science Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 4 , AECOM, Pittsburgh, Pennsylvania, United States
Show AbstractSolid oxide fuel cells (SOFCs) are a promising technology for efficient, scaleable generation of electricity from a variety of fuels with low emissions and straightforward carbon capture. SOFC electrodes are porous composites of inorganic materials that facilitate the transport of both oxide ions and electrons. The microstructure of the electrodes’ constituent materials, particularly the interfaces between phases and the triple junctions between the two solid phases and a pore, is critical to understanding both the performance and the longevity of SOFCs. Therefore, characterizing the microstructure using 3D tomographic techniques, such as x-ray computed tomography and focused ion beam scanning electron microscopy, offers valuable insight into mechanisms of degradation and can help identify opportunities for performance improvement through electrode engineering.
Through such tomographic characterization, we have identified sources of microstructural heterogeneity beyond the level of the existence of discrete phases, all of which can vary based on material selection and manufacturing method. For example: broad particle size distributions, self-aggregation of one or more phases, gradients in composition, and inclusions like macropores and particularly large particles. The presence and severity of these different sources of heterogeneity with different characteristic wavelengths affect the representative volume element (RVE) of microstructure that must be studied to draw meaningful conclusions about e.g. degradation mechanisms. They can also affect the cell’s performance and the rate of performance degradation. In this work, we examine the presence of these sources of heterogeneity, the length scales across which they occur, and their effect on the RVE size and electrochemical performance. We do this by examining SOFC electrodes with 3D tomographic techniques over large volumes where these different kinds of heterogeneity can be observed, and by creating simulated microstructures where these different sources of heterogeneity are deliberately varied. We find that the RVE size varies strongly with the introduction of longer wavelength sources of heterogeneity, ranging from tens to hundreds of multiples of an average grain diameter. The results are applicable to any multi-phase material system where the distribution of microstructural features, e.g. interfaces and triple phase junctions, is important to the system’s functioning.
8:00 PM - ES04.19.43
Hierarchically Porous Microspheres Outperform Nanoporous Particles—A Pore-Scale Modeling Study for Fuel Cell Catalyst Layer Application
Mohammadamin Sadeghi 1 , Zishuai Zhang 1 , Mahmoudreza Aghighi 1 , Jake Barralet 1 , Jeff Gostick 1 2
1 , McGill University, Montreal, Quebec, Canada, 2 , University of Waterloo, Waterloo, Ontario, Canada
Show AbstractThe traditional and intuitive approach for increasing the reactivity of a porous catalyst particle involves increasing the internal surface area by decreasing the pore size. However, this approach can have the unintended yet unfavorable outcome of reducing the transport rates of reactants and products within the particle. To circumvent this issue, one could improve transport properties of species by introducing macropores into the porous matrix, which can be achieved by the use of porogens. Modeling particles with such a complex internal structure can potentially be used to guide experimentalists creating porous particles with optimized activity. Such particles can be assembled together to be used as the fuel cell catalyst layer. In many cases, the particle is microscopic, or the porous domain is heterogeneous, meaning that single values for effective parameters like porosity or tortuosity cannot be obtained. In these cases, classic volume-averaged approaches are not suitable for modeling reactive transport. We propose a general pore-scale framework based on pore networks for modeling reactive transport in porous materials with a hierarchy of porosity. The pore network approach maps the porous domain into a network of void spaces (pores) that are connected through virtual tubular bodies (throats). The main advantage of pore network modeling is that effective parameters are no longer needed since transport equations are solved at resolution. The model is demonstrated in the context of a nanoporous particle interlaced with macropores that result from the use of porogens. Simulations show that the structural features of the porous material (ex. nanoporosity) significantly influences its bulk properties such as net reaction rate. Specifically, when increasing the nanoporosity, the total reaction surface increases, yet the net reaction rate does not monotonically increase since diffusion becomes limited. Furthermore, the effect of the shape of porogen is studied. We demonstrate that the use of rod-shaped porogens is favored compared to spherical ones. The findings of this work are further confirmed by an experimental study done in our research group.
8:00 PM - ES04.19.44
Hierarchically Porous Carbon Nanotube Microspheres for Fuel Cell Application
Zishuai Zhang 1 , Amin Sadeghi 1 , Siyu Ye 2 , Jeff Gostick 3 , Geraldine Merle 1 , Jake Barralet 1
1 , McGill University, Montreal, Quebec, Canada, 2 , Ballard Power Systems Inc., Burnaby, British Columbia, Canada, 3 Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
Show AbstractDeveloping electro-catalysts with both high stability and efficiency for oxygen reduction reaction (ORR) is critical for fuel cell application. Several studies indicate that platinum utilisation is in the order of 20-35%.[1] Carbon nanotubes is a strong candidate to electrically support Pt nanoparticles for ORR. Over the past few decades, a plethora of publications has flourished to take advantage of its excellent corrosion resistance, thermal stability and high electrical conductivity [2]. Nevertheless, this low dimensional nanomaterial is still not commercially used in PEMFC due to its toxicity for the user/manufacturer. A low cost and readily available method based on ultrasonic bonding has been developed in our lab and successfully applied to CNTs, leading to 3 dimensional porous structures.[3] Our ability to make interconnected network could eliminate issues of Pt utilisation by improving microstructures, minimising interfacial resistance and optimising interactions between catalyst and support. Assembling these CNTs generated materials with poor oxygen diffusion especially in the thicker CNTs layers. To address this issue and further accelerate the charge (electronic and protonic) exchange, aragonites rods (ca. 0.1×1 um) have been synthesised and assembled simultaneously with CNTs. We assume that by choosing a rod-shaped porogen will favour the connection between the different porosity both at the surface and within the microspheres, thus facilitating the flow of reactants to more electrocatalytically sites and so increasing the Pt utilization. After assembly, the aragonite porogen within the 3D CNT structures were gently removed.
The results proved that a higher percentage of porogen (0, 10, 20, 30 and 40 wt%) leads to a larger macro-pore volume and a better catalytic activity. Among all of these catalysts, the 40 wt% aragonite carbon nanotubes microspheres (CNM-40) have both good catalytic activity (0.032 A mgPt -1, 0.9V) and durability (70% current remains after 20000s, chronoamperometry curves obtained at 0.6V vs RHE in O2-saturated 0.1M HClO4). The findings of this work is further confirmed by a modeling study done in our research group.
To further improve catalytic activity and durability, the face-centered tetragonal (fct) structural PtFe alloy was synthesized through ethylene glycol reduction and heat annealing, showing remarkably improved ORR activity (0.082 A mgPt -1, 0.9V) and anti-dissolution ability (90% current remains after 20000s, 0.6V vs RHE) in acidic condition due to the change of both geometric and electronic structures of platinum atoms.
[1] B. Krishnamurthy, S. Deepalochani, International Journal of Electrochemical Science. 2009, 4, 386.
[2] A. Lekawa-Raus, J. Patmore, L. Kurzepa, J. Bulmer, K. Koziol, Adv. Funct. Mater. 2014, 24, 3661.
[3] D. C. Bassett, G. Merle, B. Lennox, R. Rabiei, F. Barthelat, L. M. Grover, J. E. Barralet, Adv. Mater. (Weinheim, Ger.). 2013, 25, 5953.
8:00 PM - ES04.19.45
Visualizing Ion Transport in Battery Electrolyte During Lithium Deposition
Qian Cheng 1 , Yuan Yang 1
1 , Columbia University, New York, New York, United States
Show AbstractLithium is an attractive for recharaeable batteries as it has high theoretical capacity of 3840 mAh/g, 10 times that of conventional graphite anode. However lithium metal failed to be a commercial anode due to the safety issue and low cycling ability caused by growth of dendrite and formation of dead lithium, respectively. The uneven distribution of current lead to the nucleation of lithium seed, further lead to the growth of dendrite. Current strategies to prevent the growth of dendrite include the artificial SEI and lower the current density of collector.
There have been growing researches on lithium electrodes lately but most of them focused on the protection of lithium electrodes. Optical methods, NMR, neutron-based techniques have been used to understand the growth mechanism. However, there is little, if not no, characterizations of how ions are depleted in the electrolyte during lithium deposition.
In this work we used optical microscopy and Raman Spectroscopy to study the correlations between lithium concentration, reaction overpotential and dendrite growth. The depletion of salts is observed and its relationship with dendrite eruption is confirmed. The simulations were done by Newman’s model; the simulation results and experimental results were perfectly matched. This research give experimental support and good insight to kinetics of Lithium ion battery and inhibition of dendrite growth.
8:00 PM - ES04.19.46
Aluminum Chloride–Natural Graphite Battery and Its Energy Density
Kostiantyn Kravchyk 1 2 , Shutao Wang 1 2 , Laura Piveteau 1 2 , Frank Krumeich 1 , Maksym Kovalenko 1 2
1 Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich Switzerland, 2 Laboratory for thin films and photovoltaics, Empa–Swiss Federal Laboratories for Materials Science and Technology, Dübendorf Switzerland
Show AbstractNon-aqueous, ionic liquid-based aluminum chloride-graphite batteries emerge as a highly promising post-Li-ion technology for low-cost and large-scale storage of electricity, because it features exclusively highly abundant chemical elements and simple fabrication methods. In this work, we examined the recently proposed aluminum–ionic liquid–graphite architecture.1 Although previous studies have focused on graphitic cathodes, we analyzed the practicality of achievable energy densities and found that the AlCl3-based ionic liquid is a capacity-limiting anode material. By focusing on both the graphitic cathode and the AlCl3-based anode, we improved the overall energy density.3,4 First, high cathodic capacities of ≤150 mAh g–1 and energy efficiencies of 90% at high electrode loadings of at least 10 mg cm–2 were obtained with highly crystalline natural graphite flakes or with synthetic kish graphite flakes, which were subjected to minimal mechanical processing. Second, the AlCl3 content in the ionic liquid was increased to its maximal value, which essentially doubled the energy density of the battery, resulting in a cell-level energy density of ≤65 Wh kg–1.
References
[1] M.-C. Lin, et al. Nature 2015, 520, 324-328.
[2] K. V. Kravchyk, et al. Chem. Mater. 2017, 29, 4484-4492.
[3] S. Wang, et al. ACS Appl. Mater. Interfaces. 2017, submitted.
8:00 PM - ES04.19.47
Enhanced Lithium-Ion Transport In Core/Shell Nanowire Heterostructures—Comparison of Electrochemical Characteristics with Si Nanowires, Si1-xGex Nanowires and Si/Ge Core/Shell Nanowire Heterostructures
Dongheun Kim 1 , Nan Li 1 , Jinkyoung Yoo 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractThe electrochemical performances of lithium ion battery anodes are governed by lithium ion transport characteristics. Group-IV semiconductors such as silicon (Si) and Ge (Ge) have large specific gravimetric capacity compared to that of graphite, the currently dominant lithium ion battery anode material. Furthermore, Si and Ge are complementary to each other from the perspective of energy density and power density. The capacity of Ge is smaller than that of Si. However, the power density, an important metric of maximum available charging rate, of Ge is significantly larger than that of Si. Concurrent achievements of large capacity and power density with Si and Ge have been tried with homogeneous Si1-xGex thin films and nanowires and SiGe nanowires with composition gradient along radial direction. The SiGe-based approaches to enhance lithium ion battery anode performances hypothesize that the compositions at the moment of synthesis are valid during the battery operation.
We studied electrochemical characteristics of Si/Ge core/shell nanowire heterostructures with electrochemical impedance spectroscopy, gravimetric capacity measurements with different charging rates, and transmission electron microscopy. We observed compositional changes of Si/Ge core/shell nanowire heterostructures over cycling of charging/discharging at various rates. Moreover, we did comparison of electrochemical performances with Si nanowires, SiGe nanowires, and Si/Ge core/shell nanowire heterostructures. The comparison revealed that Si/Ge core/shell nanowire heterostructures show higher capacity and power density than SiGe nanowires with the same amount of Ge.
8:00 PM - ES04.19.48
First-Principles and Classical Molecular Dynamics Simulation of Electrolyte/Lithium Metal Interface in Li Metal Batteries
Mahsa Ebadi 1 , Moyses Araujo 2 , Daniel Brandell 1 , Luciano Costa 3 , Matthew Lacey 1
1 Chemistry Department, Ångström Laboratory, Uppsala Sweden, 2 Physics Department, Ångström Laboratory, Uppsala Sweden, 3 , Fluminense Federal University, Niterói Brazil
Show AbstractEnergy storage systems are potential candidates in order to reduce the fossil fuel consumptions. In this context, lithium batteries could play an important role for the development of electric mobility in the form of electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles [1]. Lithium metal has the lowest reduction potential in the electrochemical reactivity series, a high theoretical specific capacity and thereby researchers have been interested in using this metal as the negative electrode in Li-based battery cells. Sulfur, oxygen or intercalation compounds can be applied as positive electrodes with the Li metal negative electrode. There exist, however, some challenges in the application of the Li metal electrode, such as safety risk and low coulombic efficiency [2]. Therefore, the research on Li metal based batteries is mostly focused on tackling the problems with this electrode or searching for more stable electrolytes with this reactive electrode material. Computational materials modelling, as a complementary technique to experimental studies, has been extensively used in the field of Li-ion batteries. However, the number of theoretical studies on Li metal electrodes have been more limited. In this research project, different molecular modelling methods have been used to study the electrolyte/Li metal electrode interface. This study consists of: 1. Electronic structure and stability of organic carbonate solvents, a common class of electrolytes, on a Li metal surface by density functional theory (DFT) methods [3]. 2. The effect of Li metal surface on dynamics and structural properties of a solid polymer electrolyte (polyethylene oxide doped with LiCF3SO2NSO2CF3 sa< LiTFSI) by classical molecular dynamics (MD) simulations [4]. 3. the electronic structure, stability and X-ray photoelectron spectroscopy of the Li-sulfur battery electrolyte additive LiNO3, and some other possible decomposition products of this compound by DFT calculations [5].
Reference:
[1] W. Yuan, Y. Zhang, L. Cheng, H. Wu, L. Zheng, D. Zhao, The applications of carbon nanotubes and graphene in advanced rechargeable lithium batteries, J. Mater. Chem. A. 4 (2016) 8932.
[2] X.-B. Cheng, R. Zhang, C.-Z. Zhao, F. Wei, J.-G. Zhang, Q. Zhang, A Review of Solid Electrolyte Interphases on Lithium Metal Anode, Adv. Sci. 3 (2015) 1500213.
[3] M. Ebadi, D. Brandell, C.M. Araujo, Electrolyte decomposition on Li-metal surfaces from first-principles theory, J. Chem. Phys. 145 (2016) 204701.
[4] M. Ebadi, L.T. Costa, C.M. Araujo, D. Brandell, Modelling the Polymer Electrolyte/Li-Metal Interface by Molecular Dynamics simulations, Electrochim. Acta. 234 (2017) 43.
[5] M. Ebadi, M. J. Lacey, D. Brandell, C. M. Araujo, Density functional theory modelling interfacial anode reactions of the LiNO3 additive in lithium-sulfur batteries by means of simulated photoelectron spectroscopy. In manuscript.
8:00 PM - ES04.19.49
Novel Environmentally Friendly Synthesis of Nanoporous Copper for Asymmetric Supercapacitors and Other Applications
Kostiantyn Turcheniuk 1 , Benjamin Zusmann 1 , Xiaobo Zhang 1 , Jim Benson 1 , Wenbin Fu 1 , Samuel Nelson 1 , Alexandre Magasinski 1 , Gleb Yushin 1
1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractIn this work, we report on a novel, inexpensive and environmentally friendly synthesis of nanoporous copper (Cu). In contrast to traditional synthesis routes, which rely on the use of anodization or sacrificial templates or lasers or highly-corrosive chemicals (such as hydrochloric, nitric, perchloric acids, and sodium hydroxide [1]), the reported approach does not require elaborate procedures or expensive equipment and does not produce harmful waste products. The produced nanoporous Cu exhibits tunable bi-continuous structure with open porosity. It may be utilized as a catalyst or catalyst support, as anti-bacterial agent, as highly electrically conductive substrate for deposition of active nanomaterials for use in high power energy storage devices and other applications.[2]
Asymmetric supercapacitors offer higher power than batteries and higher energy than supercapacitors.[3] In a sub-class of these devices, Li-ion capacitors, one of the electrodes (typically anode) stores ion via intercalation of Li ions, while the other (typically cathode) relies on electrical double-layer capacitance on the surface of porous carbon.[4] In prior studies, high-rate lithium titanate (LTO) has been utilized as an anode in such devices, but due to low electrical conductivity and only moderately high ionic conductivity of LTO, its rate performance was insufficiently good.[5] By incorporation of LTO nanoparticles into nanopores of conductive activated carbon, our group has recently demonstrated quite remarkable enhancements in LTO rate performance.[6] Nanoporous metals, such as copper, offer dramatically higher (by ~1000x or more) electrical conductivity than porous carbons [1] and thus may offer even better power density characteristics. In one illustrative example of this work, we show that deposition of lithium titanate (LTO) or TiO2 on porous Cu surface produces anodes for asymmetric supercapacitors, which offer substantially higher volumetric capacitance at both low and high charge-discharge rates when compared to commercial porous carbon double-layer electrodes.[7]
References:
1. Ding, Y. and Z. Zhang, Nanoporous metals for advanced energy technologies. 2016: Springer.
2. Gawande, M.B., et al., Cu and Cu-based nanoparticles: synthesis and applications in catalysis. Chemical reviews, 2016. 116(6): p. 3722-3811.
3. Choi, N.S., et al., Challenges facing lithium batteries and electrical double layer capacitors. Angewandte Chemie International Edition, 2012. 51(40): p. 9994-10024.
4. Naoi, K., et al., High-rate nano-crystalline Li 4 Ti 5 O 12 attached on carbon nano-fibers for hybrid supercapacitors. Journal of Power Sources, 2010. 195(18): p. 6250-6254.
5. Nitta, N., et al., Li-ion battery materials: present and future. Materials today, 2015. 18(5): p. 252-264.
6. Zhao, E., et al., Lithium Titanate Confined in Carbon Nanopores for Asymmetric Supercapacitors. ACS Nano, 2016. 10(4): p. 3977-3984.
7. Zhang, X. et al. 2017 (in preparation).
8:00 PM - ES04.19.50
Stabilizing Nickel Catalyst Particles in Ni-YSZ Cermet Electrodes by Engineering the Morphology of Infiltrated Metallic and Oxide Phases
Yanchen Lu 1 , Paul Gasper 1 , Boshan Mo 1 , Srikanth Gopalan 1 , Uday Pal 1 , Soumendra Basu 1
1 , Boston University, Brookline, Massachusetts, United States
Show AbstractHydrogen generation and storage are a critical part of a sustainable energy future; a key technology for the production of energy from hydrogen fuel is the solid oxide fuel cell (SOFC). State-of-the-art SOFCs are most commonly made up of a thick Ni-YSZ fuel electrode, YSZ electrolyte, and an LSM air electrode. One challenge for implementing SOFCs is tolerance of the fuel electrode to common fuel impurities, such as sulfur and carbon monoxide. Liquid infiltration of various metallic nanoparticles into the fuel electrode has been shown in many studies to improve fuel electrode sulfur tolerance, coking tolerance, and overall cell performance. However, metallic nanoparticles are less stable than the electrode on which they are deposited. Thus, improving nanoparticle stability extends SOFC lifetime. This study examines the stability of liquid infiltrated nickel nanoparticle catalysts in standard SOFC operating conditions, revealing coarsening and transport of nickel nanoparticles away from the electrode-electrolyte interface after electrochemical testing. Coarsening and transport of metallic nanoparticles occurs through two primary mechanisms: surface diffusion and vapor phase diffusion. These degradation mechanisms can be mitigated by anchoring or covering catalyst particles with a thin infiltrated oxide layer. Electronic or mixed ionic-electronic conducting (MIEC) oxides can provide additional benefits by adding new electronic pathways for catalyst particles as well as fuel impurity tolerance.
TEM analysis of co-deposited nickel and gadolinium doped ceria (GDC), a common MIEC material, shows that nickel lies on top of the infiltrated GDC, which doesn’t prevent coarsening mechanisms. Electrochemical testing of the electrode with co-deposited nickel and GDC corroborates this hypothesis, with post-testing fracture SEM showing that the nickel particles are unstable near the electrode-electrolyte interface. Sequential liquid infiltration of nickel nanoparticles and an oxide layer ensures that oxide deposition occurs on top and around metallic catalyst particles. Electrochemical testing of sequentially infiltrated metallic catalysts and an anchoring oxide show improved catalyst durability, showing that liquid infiltration of oxide phases can be used to improve the long-term stability of metallic nanoparticles in SOFC electrodes.
8:00 PM - ES04.19.51
Large-Scale DFT Simulation about Insertion and Extraction of Li’s for Quinons@SWCNT for Rechargeable Battery
Takahiro Tsuzuki 1 , Shuji Ogata 1 , Masayuki Uranagase 1
1 , Nagoya Inst of Technology, Nagoya Japan
Show AbstractThe lithium ion battery has become an indispensable energy storage device for various electronic systems such as PC. Expecting wider-spread usage of the battery, the system of quinone molecules encapsulated in the single-wall carbon nanotube (SWCNT), which is free from rare-metals as Co, has been proposed as a next-generation cathode electrode material [Ishi et al., Phys. Chem. Chem. Phys. 18, 10411 (2016)]. The dissolution of quinone molecules into liquid electrolyte is suppressed by the encapsulation. In this presentation, we report our large-scale (containing thousands of atoms) first-principles simulation results about the structure of quinone molecules and their dynamics in insertion and extraction of Li's from SWCNT.
Due to substantial charge-transfer and chemical reaction between quinines and SWCNT, we should perform the simulation at electronic level using the density-functional theory (DFT) instead of using an empirical inter-atomic potential. Our real-space grid implementation of the density-functional theory (RGDFT), in which the finite difference method is used for derivatives of the Kohn-Sham orbitals and Hartee field, has attractive features of parallelizability and applicability to various boundary conditions in addition to universality in target materials. Taking the divide-and- conquer strategy we have recently developed the linear-scaling, divide-and-conquer-type RGDFT (DC-RGDFT) code [Ohba, Ogata et al., Comp. Phys. Commun. 183, 1664 (2012)] for large-scale simulation with short computation timings. The empirical VdW potential called DFT-D2 is added in the present study.
Following the experimental settings, 9,10-phenanthrene-quinone (PhQ) is considered. We first set a SWCNT with diameter 1.6nm (length 5nm) with metallic chirality. Significant electron-transfer from PhQ to SWCNT is observed when the PhQ is inserted in the SWCNT. Two cases of boundary conditions are considered for the SWCNT: one is H-termination under free boundary to mimic the end regions of an experimental SWCNT, the other is the periodic boundary condition for the middle region. The PhQs with about 20% of the total weight, which corresponds to the experimental value, are inserted in the SWCNT. Through the simulation runs, we find that the SWCNT deforms substantial during the relaxation of the PhQs and that the Li-ions act to bind the PhQs. Significant re-arrangements of the PhQs during the adsorption and release of Li-ions are found. We will clarify the Li-transfer paths during the insertion and extraction of Li's from PhQ@SWCNT.
8:00 PM - ES04.19.52
Lithium-Sulfur Batteries with the Lowest Self-Discharge and the Longest Shelf-Life
Sheng-Heng Chung 1 , Arumugam Manthiram 1 2
1 Texas Materials Institute, The University of Texas at Austin, Austin, Texas, United States, 2 Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas, United States
Show AbstractIn the search for inexpensive and high-energy-density rechargeable batteries for electric vehicles and portable devices, lithium-sulfur batteries fabricated with low-cost, high-capacity sulfur cathodes (1,675 mA h g-1) have garnered significant attention. However, sulfur cathodes encounter dynamic and static electrochemical instabilities due to the formation of soluble polysulfide intermediates (Li2Sx, x = 4 – 8) and their migration to the anode during cycling (dynamic instability) and storage (static instability). The irreversible relocation of polysulfides in the cell contributes to the corrosion of lithium-metal anode, degradation of sulfur cathodes, and surface passivation of both the electrodes. The static polysulfide diffusion further leads to severe self-discharge and short shelf-life during cell resting. Moreover, the polysulfide dissolution and diffusion damage the integrity and stability of the electrodes. This ultimately leads to battery failure and safety concerns, hindering the progress towards commercialization.
However, only a few studies focusing on the self-discharge of lithium-sulfur cells have appeared thus far. According to all the articles reporting self-discharge in the literature, the lithium-sulfur batteries suffer from severe self-discharge with a high capacity-fade rate of over 50% in a month or less. The self-discharge problem becomes even worse when the electrode has a reasonable sulfur content of above 65 wt.% and a mass loading of above 2 mg cm-2. Thus, the self-discharge of lithium-sulfur batteries is a much more serious issue compared to that of lithium-ion batteries (less than 3% per month). Unfortunately, many self-discharge studies on lithium-sulfur batteries in the literature have reported only a short-term analysis. This indicates an unknown area for long-term static lithium-sulfur battery chemistry and limits the corresponding improvements.
In regards to the static electrochemical stability, we present here the realization of low self-discharge (LSD) lithium-sulfur batteries. The LSD lithium-sulfur batteries exhibit (i) a low capacity-fade rate of only 0.14% per day, (ii) the longest shelf-life of one year, and (iii) excellent cyclability with a high capacity-retention rate of 92% after resting for one year and then continuously cycling for 100 cycles. Their superior electrochemical stability reflects in the lowest self-discharge constant of only 0.0022 per day. A subsequent comparison of the LSD lithium-sulfur batteries with the control lithium-sulfur batteries fabricated with conventional cathodes provides meaningful insights on why the conventional lithium-sulfur cells have fast self-discharge, short shelf-life, and poor cyclability. Finally, a comparative analysis with the literature values demonstrates that our LSD lithium-sulfur batteries exhibit greatly improved static electrochemical stability and offer more than 12 times improvement in the cell shelf-life.
8:00 PM - ES04.19.53
Lithium-Coated Polymeric Matrix as a Minimum Volume-Change and Dendrite-Free Lithium Metal Anode
Yayuan Liu 1 , Dingchang Lin 1 , Yi Cui 1
1 , Stanford University, Stanford, California, United States
Show AbstractLithium metal is the ideal anode for the next generation of high-energy-density batteries. Nevertheless, dendrite growth, side reactions and infinite relative volume change have prevented it from practical applications. Here, we demonstrate a promising metallic lithium anode design by infusing molten lithium into a polymeric matrix. The electrospun polyimide employed is stable against highly reactive molten lithium and, via a conformal layer of zinc oxide coating to render the surface lithiophilic, molten lithium can be drawn into the matrix, affording a nano-porous lithium electrode. Importantly, the polymeric backbone enables uniform lithium stripping/plating, which successfully confines lithium within the matrix, realizing minimum volume change and effective dendrite suppression. The porous electrode reduces the effective current density; thus, flat voltage profiles and stable cycling of more than 100 cycles is achieved even at high current densities in both carbonate and ether electrolyte. The advantages of the porous, polymeric matrix provide important insights into the design principles of lithium metal anodes.
8:00 PM - ES04.19.54
Structural and Chemical Evolution of Thin-Film LiCoO2 Electrodes During Delithiation/Lithiation
Zhenzhong Yang 1 , Timothy Droubay 1 , Mark Bowden 2 , Mark Engelhard 2 , Zhenxing Feng 3 , Le Wang 1 , Yingge Du 1
1 Physical & Computational Sciences Directorate, PNNL, Richland, Washington, United States, 2 Environmental Molecular Sciences Laboratory, PNNL, Richland, Washington, United States, 3 , Oregon State University, Corvallis, Oregon, United States
Show AbstractLithium cobalt oxide (LiCoO2, LCO) is one of the most extensively studied/used cathode materials for rechargeable lithium ion batteries. Well-defined, single crystalline LiCoO2 thin films and multilayered structures are highly desirable for fundamental investigations of the charge/discharge processes. In our work, epitaxial LiCoO2 thin films with different orientations and strain states were grown by pulsed laser deposition (PLD). All-solid-state thin film battery was constructed under scanning transmission electron microscopy (STEM) in combination with oxide electrolyte and metallic Li contact. In situ (S)TEM was employed to investigate the structural and chemical evolution of the constructed LCO thin film electrode during delithiation/lithiation. EELS, EDX, and NBD were used to study the reaction product, lithium diffusion pathways, and intercalation induced phase changes, in particular occurring at the electrolyte/cathode interfaces. These results will be compared to electrochemical cycling performance measured with traditional techniques to establish connections between atomic-level structure evolution and microscopic change in electrochemical characteristics.
8:00 PM - ES04.19.55
Electrocatalytic Activity of Some Cobalt Based Sodium Phosphates in Alkaline Solution
Debasmita Dwibedi 1 , Prabeer Barpanda 1
1 , Indian Institute of Science, Bangalore India
Show AbstractElectrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are central to water electrolysis, artificial photosynthesis and rechargeable metal-air batteries. In rechargeable metal-air batteries, OER take place during charge and the ORR in discharge process, which are expected to occur reversibly. However, the kinetics of these OER/ORR reactions are slow and sluggish. Catalysts are designed for this purpose to fasten these kinetics. Noble metals like Pt-based materials are well known catalysts for ORR due to their highest activity, whereas Ru- and Ir-based materials are highly active catalysts for OER. However, these noble metal catalysts are expensive and show poor stability limiting in large-scale applications.
Recent reports demonstrate the phosphate-based materials could be very efficient catalysts for OER and ORR. For example, cobalt phosphate nanoparticles decorated with nitrogen-doped carbon (Co3(PO4)2@N-C) exhibited efficient and stable OER activity with low onset potential in strong alkaline medium. Very recently, sodium metal phosphates NaCoPO4 and Na2CoP2O7 were studied as electrocatalyst for OER. The Na2CoP2O7 with distorted cobalt tetrahedral geometry exhibited enhanced activity and stability relative to cobalt phosphate. This report demonstrates that surface reorganization by the pyrophosphate ligand induces distorted cobalt tetrahedral geometry and favors binding of water molecules. It leads to low overpotential (~0.42 V) for water oxidation. Particularly, polyanions affect the OER and ORR performance of the catalysts. Mn3(PO4)2 in neutral solution shows the positive effect of polyanion. The phosphate framework was found to stabilize the Mn3+ active sites much better than in manganese oxides. Due to these benefits of phosphate frameworks, our principal focus was to investigate the ORR and OER activity of new phosphate-based systems namely Na2Co2Fe(PO4)3, NaCoPO4 and Na2CoP2O7. To the best of our knowledge, no work has been reported on electrocatalytic ORR activity of the alluaudite type Na2Co2Fe(PO4)3, maricite type NaCoPO4 and Na2CoP2O7 in alkaline solution.
In the present work, sodium iron cobalt phosphates (Na2Co2Fe(PO4)3) and sodium cobalt phosphates (NaCoPO4 and Na2CoP2O7) were synthesized by energy savvy solution combustion technique. Crystal structure of these materials was investigated using XRD Rietveld refinement technique. The electrochemistry in Na2Co2Fe(PO4)3 will be demonstrated using galvanostatic charge discharge techniques. The electrocatalytic properties of these phosphates were examined by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and Chronoamperommetry (CA) techniques with RRDE in presence of Na+ ion containing aqueous electrolyte (1 M NaOH). In the current work, the electrocatalytic activities of sodium iron cobalt phosphates and sodium cobalt phosphates, and possible effects of phosphate frameworks on electrocatalytic activity will be discussed.
8:00 PM - ES04.19.56
Carbon Nanotubes Branched on Three-Dimensional, Nitrogen-Incorporated Reduced Graphene Oxide/Iron Oxide Hybrid Architectures for Lithium-Ion Battery Anode
Yingbo Kang 1 , Puritut Nakhanivej 1 , Ho Seok Park 1
1 Chemical Engineering, Sungkyunkwan University, Suwon Korea (the Republic of)
Show AbstractThe carbon nanotubes (CNTs) branched on three-dimensional (3D) macroporous, nitrogen-incorporated reduced graphene oxide (NG)/iron oxide (CNT/NG-Fe) hybrid architectures have been prepared via an ice templating and microwave synthesis. Compared with the pristine RGO, the CNTs can be more readily and uniformly grown on the 3D NG surfaces due to the good electronic conductivity by N-type configurations. As demonstrated by the electrochemical performances, the discharge capacity of the 3D CNT/NG-Fe is 1208 mAh g-1 at 50 mA g-1 which is greater than 890 and 820 mAh g-1 of the CNT/G-Fe and NG. When the rate increases from 100 to 1000 mAh g-1, the capacity retention reaches 52 % of initial capacity corresponding to the discharge capacity of 947 mAh g-1. After 130 cycles at 100 mA g-1, the capacity gradually increases to 1020 mAh g-1 with the Coulombic efficiency of > 98.5 %. The enhanced capacity, rate capability and cyclic stability of the CNT/NG-Fe are associated with the doping effect of N-configuration and unique hierarchical structure consisting of the dense CNT branches on 3D macroporous continuity. The features of this complex hybrid architecture can be described along the following lines. (1) The 3D N-incorporated RGOs act as conductive networking substrate to provide large surface area for the deposition of iron oxide nanoparticles, to facilitate Li ion transport and to delocalize stress created by volume expansion during charge/discharging process. (2) The CNT branches offer 1D conducting pathway between intra- or interparticles and inhibiting restacking of RGO nanosheets. (3) The iron oxide nanoparticles are high capacity materials for enhancing charge storage capacity of carbon nanomaterials.
8:00 PM - ES04.19.57
How to Determine Transport Parameters of Lithium-Ion Battery Separators
Raphael Zahn 1 , Marie Francine Lagadec 1 , Vanessa Wood 1
1 , ETH Zurich, Zurich Switzerland
Show AbstractLi-ion battery (LIB) separators are porous membranes that electronically isolate the battery’s electrodes yet allow ionic transport between them. As a result, the optimal separator design is a tradeoff between high cycling performance and battery safety.1
Separator performance is commonly described by the ratio of the conductivity of the pure electrolyte, σ0, divided by the conductivity of the separator filled with electrolyte, σeff, the so-called MacMullin number, NM.2 Thus, the MacMullin number also relates the diffusion coefficient of ions in the electrolyte, D0, to the effective diffusion ions in the electrolyte filled separator, Deff, and therefore can be described as ratio of the separator’s tortuosity, τ, and porosity, ε,3
NM = σ0/σeff = D0/Deff = τ/ε (1).
Equation (1) suggests three different approaches for determining the MacMullin number of separator membranes: (i) the ionic conductivities σ0 and σeff can be measured using electrochemical impedance spectroscopy (EIS), (ii) the diffusion coefficients D0 and Deff are commonly determined from steady-state numerical diffusion simulations applying an ionic concentration gradient across the separator membrane, and (iii) geometrical approaches are used to determine τ and ε directly from separator microstructures. Surprisingly, the MacMullin number of most separators as measured by EIS is a factor 2-4 larger compared to values determined by steady-state diffusion simulations or geometrical approaches.4, 5
Here, we characterize a commercially available polyethylene separator using EIS and FIB-SEM tomography and determine its MacMullin number based on its ionic conductivities (σ0 and σeff by EIS), and by steady-state diffusion simulations.5, 6 We show that EIS and diffusion simulations probe the separator at different length scales, and that the two methods consider certain geometric features such as non-interconnected voids (dead ends) in different ways.
We analyze the fractal properties (fractal dimension, spectral dimension) of polyolefin separators and use these parameter to determine their transport parameters in a new way. We show, for the first time, that the so-determined MacMullin number agrees with the MacMullin number as determined by EIS. We discuss implications for LIB performance and advise on appropriate use of the different ways to determine the MacMullin number for LIB separators.
References
1. P. Arora and Z. J. Zhang, Chem. Rev., 2004, 104, 4419-4462.
2. S. S. Zhang, J. Power Sources, 2007, 164, 351-364.
3. M. Ebner and V. Wood, J. Electrochem. Soc., 2014, 162, A3064-A3070.
4. J. Landesfeind, J. Hattendorff, A. Ehrl, W. A. Wall and H. A. Gasteiger, J. Electrochem. Soc., 2016, 163, A1373-A1387.
5. R. Zahn, M. F. Lagadec, M. Hess and V. Wood, ACS Appl. Mater. Interfaces, 2016, 8, 32637-32642.
6. M. F. Lagadec, M. Ebner, R. Zahn and V. Wood, J. Electrochem. Soc., 2016, 163, A992-A994.
8:00 PM - ES04.19.58
High Performance Palladium Intermatallics for Electrochemical Oxygen Reduction
Du Sun 1 , Shoji Hall 1
1 , Johns Hopkins University, Baltimore, Maryland, United States
Show AbstractThe conversion of O2 to H2O is an important fuel cell reaction for the recovery of renewable electricity from chemical fuels. To date, most materials utilized for the oxygen reduction reaction (ORR) consist of noble metal rich alloys of the form Pt3X or PtX, where X is an earth abundant element. Although catalysts of this type have been demonstrated to exhibit high activity for ORR, the >50% Pt loading translates to a relatively modest decrease in the use of Pt. Pd alloy catalysts have been proposed as an alternative to Pt and Pt alloy catalysts; however lower catalytic performance relative to Pt has prevented these materials from attracting considerable attention. Recently, we have found that earth abundant metal rich Pd alloys outperform Pt and Pd metal in alkaline media; the mass activity of our unsupported Pd alloy reach 1.3 A/mgPd, which is nearly 100X higher than Pt/C (~0.045 A/mgPt) and Pd/C (~0.040 A/mg) at 0.9 V vs RHE in 0.1 M KOH. In addition to high perforance catalytic activity, our material exhibits no decrease in catalytic activity after 5000 cycles. Pd alloys are promising candidates for replacing Pt in low-temperature fuel cells because 1) Pd is ~1/3 the cost of Pt (average cost for the past decade) 2) earth-abundant metal rich Pd alloys (< 50% Pd) significantly reduce the amount of noble metal usage. Here, we demonstrate that earth abundant rich alloys of Pd are viable alternatives to Pt for ORR, and structure-property relationships will be discussed.
8:00 PM - ES04.19.59
Interface Identification of the Solid Electrolyte Interphase on Graphite—Atomistic Model and Density Functional Theory Study
Elena Zvereva 1 2 3 , Damien Caliste 1 2 , Pascal Pochet 1 2
1 , Université Grenoble Alpes, Grenoble France, 2 , CEA, Grenoble France, 3 SRSMC, université de Lorraine, Nancy France
Show AbstractWhile experimental data have revealed that the solid electrolyte interphase (SEI) in lithium ion-batteries consists of inorganic, organic and polymeric components; the fine structure at the interface with graphite is mainly unknown. The latter is a crucial point determining stability and properties of the SEI and efficient battery operation as a result.
We have evaluated, within Density Functional Theory framework, various types of graphite – lithium carbonate interfaces as prototypes of the SEI [1]. The two material connections have been evaluated using various criteria such as the formation energy, the electrostatic potential, the dipole moment magnitude, etc. It is found that only an (a,b)-oriented Li2CO3 slab adheres efficiently to the graphite. Indeed, with this orientation, the two compounds can combine their structural features to reproduce the coordination environment of ions, resulting in an adhesive energy of 116 meV/Å2. The peculiar charge distribution in this structure is also inducing an electrical potential gradient, such a gradient having been experimentally observed. In addition, we have used this model interface to study the formation and migration of point defects at the interface. It appears that lithium diffusion is driven by interstitials and that the existing potential gradient is assisting the intercalation up to 70%.
Through various criteria and various chemical bonding hypothesis, we are proposing an atomistic model of the interface between graphite and the SEI.
[1] Zvereva E., Caliste D. and Pochet P. Carbon 111 (2017), pp. 789-795, 10.1016/j.carbon.2016.10.063
8:00 PM - ES04.19.60
Decorating Graphene Oxide with Ionic Liquid Nanodroplets—An Approach Leading to Energy Dense, High Voltage Supercapacitors
Zimin She 1 , Debasis Ghosh 1 , Michael Pope 1 , Irene Lau 1
1 , University of Waterloo, Waterloo, Ontario, Canada
Show AbstractA major stumbling block in the development of high energy density graphene-based supercapacitors has been maintaining high ion-accessible surface area combined with high electrode density. Herein we develop an ionic liquid (IL)-surfactant microemulsion system which is found to facilitate the spontaneously adsorption of IL-filled micelles onto graphene oxide (GO). This adsorption distributes the IL over all available surface area and provides an aqueous formulation that is slurry cast onto current collectors, leaving behind a dense nanocomposite film of GO/IL/surfactant. Removing the surfactant and reducing the GO through a low temperature (360 °C) heat treatment, the IL plays a dual role of spacer and electrolyte. We study the effect of IL content and operating temperature on the performance, demonstrating a record high gravimetric capacitance (302 F/g at 1 A/g) for 80 wt% IL composites. At 60wt% IL, combined high capacitance and bulk density (0.76 g/cm3) yields one of the highest volumetric capacitances (218 F/cm3, 60 wt% IL at 1 A/g) ever reported for a high voltage IL-based supercapacitor While achieving promising rate performance and cycle-life, the approach is compatible with slurry casting procedures and eliminates the long and costly electrolyte imbibition step since the electrolyte is cast directly with the electrode material.
8:00 PM - ES04.19.61
Fabrication of Enzyme-Based Anode on Multi-Walled Carbon Nanotubes as Active Electrodes in Biofuel Cells
Selma Mutlu 1 , Samet Sütcü 1 , Hürkan Çatalkaya 1
1 Department of Chemical Engineering, Hacettepe University, Çankaya, Ankara, Turkey
Show AbstractIn this study, glucose oxidase based bioanode used in an enzymatic biofuel cell was prepared by using carbon nanotubes (CNTs). Polyethyleneimine was chosen as the carrier polymer and ferrocene-carboxy-aldehyde was chosen as the mediator in order to be used for transferring of electrons that occur in oxidation reaction. For the preparing method of the bio-anode, firstly ferrocene-carboxy-aldehyde-polyethyleneimine polymer (Fc-PEI) was synthesized. The synthesized polymer with ferrocene groups was adsorbed on the multi-walled carbon nanotubes (MWCNTs), then the latter mixture were homogeneously spread on carbon cloth. This layer was treated with glutaraldehyde (GA) to cross-link the CNTs with Fc-PEI on the carbon cloth as well as to provide the aldehyde groups to immobilize enzyme. At the final step, the bio-anode was obtained by the immobilization of the glucose oxidase to the aldehyde groups on the carbon cloth. The surface of the prepared electrode was characterized by using the Atomic force microscopy(AFM). The performance of the anode was tested by the measurement of the current that was generated in the biofuel cell. The increase in current density was showed that the presence of CNTs improved the enzyme binding capacity as well as its’ activity.
8:00 PM - ES04.19.62
Ultrahigh Areal Performance from High Mass Loading Electrodes Enabled by Dry Compressible Holey Graphene
Yi Lin 1 , Jae-Woo Kim 1 , John Connell 2
1 , National Institute of Aerospace, Hampton, Virginia, United States, 2 Advanced Materials and Processing Branch, NASA Langley Research Center, Hampton, Virginia, United States
Show AbstractHoley graphene is a structural derivative of graphene with arrays of through-thickness holes, which have recently received considerable attention for applications in sensors, catalysis, separation membranes, and energy storage. In this presentation, we will discuss our recent discovery that the presence of holes through the graphene lateral surface led to unique compressibility of this material under solvent-free conditions, forming mechanically robust architectures of arbitrary shapes determined by the press die used. Dry-pressed discs thus prepared were found to be useful as electrodes for various energy storage devices such as supercapacitors and lithium-air batteries. An important attribute of this approach is the facile scalability for electrodes with ultrahigh areal mass loading with little effect on the intrinsic porosity, resulting in low ion tortuosity through the thickness of the electrodes. Another advantage is that the dry compressible holey graphene can also be used as a matrix material to host other active components such as catalysts, allowing more versatile applications. In this presentation, ultrahigh areal electrochemical performance will be demonstrated in various energy storage platforms such as supercapacitors and lithium-air batteries.
8:00 PM - ES04.19.63
Understanding Nanoscale Degradation of Silicon-Graphite Lithium-Ion Battery Anodes Using X-Ray Tomography and Cross-Sectional Electron Microscopy
Patrick Pietsch 1 , Simon Mueller 1 , Ben-Elias Brandt 1 , Paul Baade 1 , Vincent De Andrade 2 , Francesco De Carlo 2 , Vanessa Wood 1
1 , ETH Zürich, Zürich Switzerland, 2 , Advanced Photon Source, Lemont, Illinois, United States
Show AbstractDue to their high specific charge capacity, silicon and silicon-graphite based electrodes hold great promise as next generation negative electrodes for lithium ion batteries. However, detachment of the electrically connecting carbon black binder domain from the silicon active material upon electrochemical operation is a major degradation issue in these materials, leading to loss of active material and rapid capacity fade of the battery [1]. These phenomena are hard to investigate using X-ray or electron imaging techniques as the electrode constituents graphite, carbon black, silicon and the electrolyte filled pore space all consist of light elements that show weak image contrast among each other [2]. In this work, we show how to overcome these imaging challenges using a combination of staining techniques. We are able to differentiate between all phases in the electrode at different length scales and to investigate the nano-scale deformation of the carbon black binder domain upon electrochemical cycling.
References:
[1] W. Zhang, A review of the electrochemical performance of alloy anodes for lithium-ion batteries, Journal of Power Sources, 2011
[2] P. Pietsch et al., Quantifying microstructural dynamics and electrochemical activity of graphite and silicon-graphite lithium ion battery anodes, Nat. Commun., 2016
8:00 PM - ES04.19.64
Effect of Electrochemically Induced Fracture on Capacity and Kinetics of LiXMn2O4
Frank McGrogan 1 , Sean Bishop 1 , Shilpa Raja 1 , Yet-Ming Chiang 1 , Krystyn Van Vliet 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractLi-ion battery electrodes subjected to repeated electrochemical cycling suffer from limited lifetime and gradual performance loss. Many potential mechanisms of this capacity fade have been identified, including fracture of the active electrode particles due to chemomechanical stresses generated during charging and discharging. However, the extent to which this fracture contributes to both capacity fade and the growth of interfacial impedance is unclear, and the mechanisms by which fracture may affect battery performance have not been demonstrated conclusively for even well studied positive electrode systems.
Here we develop this connection between fracture, capacity, and kinetic performance in LiXMn2O4 (LMO) electrodes via electrochemical cycling designed to produce discrete fracture events. We draw on electrochemical shock theory to control fracture of the LMO particles, confirmed by concurrent acoustic emission spectroscopy and post-mortem scanning electron microscopy. We employ electrochemical impedance spectroscopy, coupled with distribution of relaxation times analysis, over a range of temperatures and cycling schedules to determine the effect of fracture on the interfacial kinetics of the electrode. These combined techniques enable us to distinguish correlation from causation in relating fracture and electrochemical changes. Moreover, this identification of the role of fracture in LMO and other positive electrode materials is critical to informing the design of Li-ion battery materials and material interfaces to confer improved longevity, late-life performance, and safety.
8:00 PM - ES04.19.66
Theoretical Pulse Charging for the Optimal Inhibition of Dendritic Deposits
Asghar Aryanfar 2 1 , Daniel Brooks 1 , William Goddard 1
2 , Bahcesehir International University , Istanbul Turkey, 1 , California Institute of Technology, Pasadena, California, United States
Show AbstractDendritic growth during electrodeposition is one of the major safety and reliability issues in rechargeable batteries. We address the role of square wave pulse on the growth dynamics of curved dendrites in continuum scale and large time periods by formulating analytical criteria. We quantify the optimum idle period based on the interplay between diffusion and electromigration as key factors for ionic flux. The accumulation of cations during pulse period in the vicinity of dendritic tips could relax during a subsequent rest period, preventing further local exponential deposition/growth. Our dimension-free analysis permits the application of our results to different scales.
8:00 PM - ES04.19.67
First-Principles Computation Study and Design for Solid Electrolyte–Electrode Interfaces in All-Solid-State Li-Ion Batteries
Yizhou Zhu 1 , Xingfeng He 1 , Yifei Mo 1
1 , University of Maryland, College Park, College Park, Maryland, United States
Show AbstractAll-solid-state Li-ion battery based on solid electrolyte materials is a promising next-generation energy storage technology, providing intrinsic safety and higher energy density. Currently, high interfacial resistance and interfacial degradation at the solid electrolyte-electrode interfaces is the key bottleneck, limiting cycling and rate performance. Fundamental understanding about the interfaces is essential, yet lacking, due to the difficulty of directly access in experiments and the complicated microstructure to construct in modeling.
In this presentation, I will show how we use first principles computation to bring new understanding about these buried interfaces. Using our developed computation approach based on large materials database, we calculated the true electrochemical stability window of solid electrolytes and predicted interphase decomposition products, which are verified by in-situ experiments. I will discuss the critical role of decomposition interphase layers and their effects on the battery performance. From these insights, we are able to classify different interface types for different solid-electrolyte and electrode pairs and estimate their impacts on battery performance. Moreover, specific interfacial engineering strategies are proposed to address potential interface issues.
In addition, I will present the predicted chemistry trend and novel strategies to enable Li metal anode. Previous research efforts to stabilize Li metal anode was greatly impeded by the lack of knowledge about Li-stable materials chemistry. With first-principles calculations based on large materials database, we found that most oxides, sulfides, and halides, which were commonly studied as protection materials, are reduced by Li metal due to the reduction of metal cations. On the contrary, nitride anion chemistry exhibits unique stability against Li metal, which is either thermodynamically intrinsic or a result of stable passivation. Many nitrides materials may be promising candidates for Li metal anode protection to achieve long-term stability. This series of computational study provides novel insights and general guidance for material design and interfacial engineering in all-solid-state Li-ion batteries.
[1] Y. Zhu, X. He, Y. Mo, Origin of Outstanding Stability in the Lithium Solid Electrolyte Materials: Insights from Thermodynamic Analyses Based on First Principles Calculations. ACS Appl. Mater. Interfaces, 7, 23685-23693 (2015);
[2] Y. Zhu, X. He, Y. Mo, First principles study on electrochemical and chemical stability of solid electrolyte-electrode interfaces in all-solid-state Li-ion batteries. Journal of Materials Chemistry A, 4, 3253-3266 (2016)
[3] F. Han§, Y. Zhu§, X. He, Y. Mo, C. Wang, Electrochemical Stability of Li10GeP2S12 and Li7La3Zr2O12 Solid Electrolytes. Adv. Energy Mater., 6, 1501590 (2016) (§ co-first author)
[4] Y. Zhu, X. He, Y. Mo, Strategies Based on Nitride Materials Chemistry to Stabilize Li Metal Anode. Adv. Sci., 1600517 (2017)
8:00 PM - ES04.19.68
Synthesis and Characterization of Nanoparticulate MgB2 for Hydrogen Storage
Keith Ray 1 , Alexander Baker 1 , Lennie Klebanoff 2 , Vitalie Stavila 2 , Jonathan Lee 1 , Tae Wook Heo 1 , Shinyoung Kang 1 , Brandon Wood 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States, 2 , Sandia National Laboratories, Livermore, California, United States
Show AbstractSolid-solid-gas boundaries in complex metal hydrides fundamentally determine the thermodynamics and kinetics of hydrogenation and dehydrogenation processes, including hydrogen dissociation, formation, and diffusion, phase nucleation, and charge transfer. Unfortunately, due to the complex heterogeneous nature of these interfaces progress toward optimization of metal hydride energy storage materials is challenging. Furthermore, while electron transfer is central to metal hydride decomposition and formation processes, it has received little attention in the hydrogen storage community, unlike more conventional electrochemical systems such as batteries. We present experimental and theoretical work examining the hydrogen adsorption properties of nanoparticulate MgB2. The preparation of nanoparticles (NPs) of MgB2 by surfactant ball milling is described, along with their characterization by X-ray absorption spectroscopy (XAS), FTIR, and XRD. Sieverts hydrogen uptake measurements are reported examining how reduction of MgB2 particle size below 50 nm influences the kinetics of hydrogenation. We also present theoretical studies of the hydrogenation of MgB2 that examine systematically how particle size influences the path of full material hydrogenation to magnesium borohydride, as well as how the charge state of Mg and B affects hydrogen uptake and phase nucleation.
Prepared by LLNL under Contract DE-AC52-07NA27344.
8:00 PM - ES04.19.69
A Nanostructure-Tunable PdCu Nanoalloy Catalyst for Oxygen Reduction Reaction
Zhipeng Wu 1 2 , Keonwoo Park 2 , Emma Hopkins 2 , Zhihui Xie 2 , Shiyao Shan 2 , Ning Kang 2 , Jin Luo 2 , Lichang Wang 1 3 , Chuan-Jian Zhong 2
1 Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin China, 2 Chemistry, SUNY Binghamton, Binghamton, New York, United States, 3 Chemistry, Southern Illinois University, Carbondale, Illinois, United States
Show AbstractThe ability to tune the nanocrystal structure of alloy nanoparticles is a great challenge in design and preparation of active and stable catalysts for green energy conversation reactions. Many fuel cell reactions such as oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR) are highly sensitive to the crystal structure of the catalysts. We reported here a nanocrystal structure tunable PdCu nanoparticle catalyst for ORR by varying thermochemical treatment parameters. The nanocrystal structures of PdCu/C catalysts strongly depend on the thermochemical treatment temperature. A PdCu catalyst with pure face-centered cubic (fcc) structure was found to exhibit the highest catalytic performance for ORR, which is almost 8 times than the commercial Pd/C catalyst in terms of mass activity. The nanostructural tuning between the fcc and body-centered cubic structures and the correlation with the catalytic activity were systematically investigated. The finding of the phase structure impact on the catalytic performance of the catalyst is further assessed by computational modeling based on density functional theory. The results provided new insights into the nanostructural-activity correlation at the atomic scale, and have significant implication to design, synthesis and processing of highly active catalysts for ORR.
8:00 PM - ES04.19.70
Fundamental Study and Design of Novel 3D Carbon Architectures for Electrochemical Applications
Jacek Jasinski 1 , Dominika Ziolkowska 1 2 , John Jangam 1 , Gamini Sumanasekera 1
1 , University of Louisville, Louisville, Kentucky, United States, 2 Faculty of Physics, University of Warsaw, Warsaw Poland
Show AbstractRecently, we have conducted in situ transmission electron microscopy (TEM) synthesis studies and developed a method of producing novel architecture 3D carbon materials with promising properties towards applications in supercapacitors and other electrochemical energy storage and conversion devices. This method uses one-step annealing of organic precursor mixed with metal salt and is based on in situ template nucleation, followed by templated catalytic growth of carbon nanostructurtes. The method allows for the synthesis of ultrafine carbon nanocages with controlled sizes and shell thicknesses. At certain conditions, the method produces highly-uniform and the smallest carbon nanocages reported [1]. These nanocages, with their bilayer structure, unimodal pore size distribution and pore size of ~2.5 nm, approach the theoretical capacity of un-doped bilayer graphene.
Here, in this work, we study the nanocage formation mechanism by analyzing how the synthesis conditions affect the properties of resulting carbon nanocages and influence the electrochemical performance of resulting supercapacitor electrode materials. We use high-resolution TEM for a direct imaging of carbon nanocage structures synthesized in situ and ex situ, and combine this study with other experimental and modeling data. The number of layers analysis is performed on hundreds of nanocages and the information on diameter, number of carbon layers and their interlayer spacing is extracted. The degree of graphitization, interlayer spacing, and pore size of carbon nanocages are correlated with their capacitive behavior. The approach provides guidelines for the optimization of the synthesis procedures for supercapacitor applications.
1. D.A. Ziolkowska, J.S.D. Jangam, G. Rudakov, T.M. Paronyan, M. Akhtar, G.U. Sumanasekera, J.B. Jasinski, Simple synthesis of highly uniform bilayer-carbon nanocages, Carbon 115 (2017) 617–624.
8:00 PM - ES04.19.71
Strong Interfacial Anchoring of Ag Nanoparticles on Engineered Perovskite Nanofibers Enabling Efficient Oxygen Reduction
Yaqian Zhang 1 , Hongbiao Tao 1 , Bin Hua 1 , Jing-Li Luo 1
1 , University of Alberta, Edmonton, Alberta, Canada
Show AbstractThe discovery of highly active and cost effective catalysts for energy conversion and storage is a key step in dealing with greenhouse gas emissions and the energy crisis. The oxygen reduction reaction (ORR) is an essential but sluggish process for many electrochemistry device, such as fuel cells and metal–air batteries. Large amounts of precious-metal electrocatalysts, e.g. Pt and its alloys, are commonly required to achieve satisfactory ORR performance. Nevertheless, the high cost, low availability, poor stability and susceptibility to fuels (eg. Methanol) of Pt all inevitably impede the industrial scale applications of Pt-based electrocatalysts. In contrast, the cost effectiveness and promising activity of perovskites has brought them under the spotlight as a new class of strong candidates for ORR catalysis.
Perovskite oxides, ABO3, have great structural and chemical flexibilities, enabling them to be easily modified to meet the requirement for efficient ORR catalysis. Over the past decade, substantial progress has been achieved in understanding and upgrading the intrinsic ORR reactivity of perovskite oxides, but efforts are still required to advance perovskite catalysts as a substitute for the state-of-the-art Pt/C.
Herein, a novel method is described to achieve high-performance ORR perovskite catalyst via combining the following three strategies to advance perovskite for ORR: 1) construct a mesoporous fibrous architecture; 2) tune the internal crystal structure to form A-site deficient layered perovskite with large amounts of ordered oxygen vacancies; and 3) ensure strong intercalation of Ag NPs in the perovskite via in situ exsolution. The electrochemical performance, morphology, crystal structure, and electronic configuration of the new catalyst, demonstrate its superiority towards ORR. The as-synthesized Ag-(PrBa)0.95Mn2O5+δ catalyst exhibits competitive activity and better durability than the state-of-the-art Pt/C for ORR. Several characterization techniques, such as TG-DTA, FESEM, HRTEM, XPS, were applied alongside density functional theory calculations to understand the possible active sites and the synergistic coupling effects that contributed to the high ORR performance. The strong interfacial anchoring of Ag NPs on ordered oxygen deficient perovskites leads to significant ligand effect and facilitates electron transfer and ion migration within the oxygen reduction reaction. The systematic engineering of perovskites described here represents a brand new approach to developing highly active and stable catalyst for energy conversion and storage.
8:00 PM - ES04.19.73
Air-Stable and Free-Standing Lithium Alloys/Graphene Foils as Alternatives to Lithium Metal
Jie Zhao 1
1 , Stanford University, Stanford, California, United States
Show AbstractAir-stable and free-standing lithium alloys/graphene foils as alternatives to lithium metal
Jie Zhao1,†, Guangmin Zhou1,†, Kai Yan1, Jin Xie1, Yuzhang Li1, Lei Liao1, Yang Jin1, Kai Liu1, Po-Chun Hsu1, Jiangyan Wang1, Hui-Ming Cheng2,3 and Yi Cui1,4*
1 Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
2 Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, the People’s Republic of China.
3 Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, 1001 Xueyuan Road, Shenzhen 518055, the People’s Republic of China.
4 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
Substantial improvements in energy density for lithium-ion batteries require the development of high-capacity electrodes. Alloy anodes with much higher capacity have been recognized as promising alternatives to commercial graphite. Without pre-stored lithium in alloy anodes, the energy density is limited by the low capacity of lithium metal oxide cathodes. Recently, Li metal has been revived as a high-capacity anode, but faces many challenges resulting from its high reactivity and uncontrolled dendrite growth. Here we develop a series of Li-containing anodes as alternatives to Li metal, inheriting the desirable properties of alloy anodes and pure metal anodes. This large-scale freestanding LixM/graphene foil (M = Si, Sn, Al etc.) consists of fine nanostructures of densely-packed LixM nanoparticles encapsulated by large graphene sheets. With fully-expanded LixM confined in the highly-conductive and chemically-stable graphene matrix, this foil maintains a stable structure and cyclability in half cells. The LixSi/graphene foil is successfully paired with high-capacity Li-free cathodes, such as V2O5 and Sulphur, to achieve stable full-cell cycling. LixM/graphene foils are stable in air, owing to their unique structure as well as the hydrophobicity and gas impermeability of graphene sheets. By addressing electrochemical and environmental stability simultaneously, these Li metal alternatives represent a significant breakthrough in battery research.
8:00 PM - ES04.19.74
Stable Electrochemical Growth Enabled by Viscoelastic Flow
Shuya Wei 1 , Lynden Archer 1
1 , Cornell University, Ithaca, New York, United States
Show AbstractElectrodeposition is used in various manufacturing processes for creating metal, colloid, and polymer coatings on conductive substrates. The process also plays an important role in electrochemical storage technologies based on rechargeable batteries, where it must be carefully managed to facilitate stable and safe operations at low operating temperatures, high rates, and over many cycles of charge and discharge. A successful electrodeposition processes requires fast transport of charged species (e.g. ions, particles, & polymers) and stable redox reactions at liquid-solid interfaces. In almost all used liquid electrolytes, deposition is subject to a variety of hydrodynamic and morphological instabilities that lead to complex transport phenomena in the electrolyte and unstable deposition, including formation of ramified structures known as dendrites on the substrate/electrode. This talk considers the stability of electrodeposition of reactive metals on planar electrodes with an emphasis on its role in enabling next-generation batteries in which metallic lithium or sodium serves as the electrode. Such batteries have been argued to offer step-change improvements in electrochemical storage technology over today’s state-of-the art lithium ion batteries and are under active investigation worldwide for high-energy, portable energy storage solutions in multiple fields. Beginning with analyses of ion transport processes and stability of electrodeposition in a high molecular weight polymer electrolyte, the talk will discuss the fundamental fluid properties such as viscosity, elasticity, electro-convection etc. of the electrolytes that affect the stability of deposition and electrode-electrolyte interphases. The talk will also discuss contemporary efforts to evaluate these approaches using electrochemical and visualization studies.
8:00 PM - ES04.19.75
Interface Degradation of Fe-Stabilized Li7La3Zr2O12 in Contact with Li
Daniel Rettenwander 1 2 , Reinhard Wagner 2 , Patrick Posch 1 , Maximilian Bonta 3 , Andreas Limbeck 3 , Georg Amthauer 2 , Martin Wilkening 3
1 Institute for Chemistry and Technology of Materials (ICTM), Graz University of Technology, Graz Austria, 2 Department of Chemistry and Physics of Materials, University of Salzburg , Salzburg Austria, 3 Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna Austria
Show AbstractRecent research has shown that Li7La3Zr2O12 (LLZO) garnets have one of the highest Li-ion conductivities (10-3 to 10-4 S cm-1) measured in crystalline phases at room temperature (RT); further, they convinced with a superior chemical as well as electrochemical stability.1 Thus, oxide garnets are exceptionally suited to be used as electrolytes in all-solid-state batteries. LLZO crystallizes either with tetragonal (I41/acd) or cubic (Ia-3d) symmetry.2,3 From the thermodynamically point of view, tetragonal LLZO, with a two magnitude lower conductivity (< 10-6 S cm-1) compared to the cubic modification, is the more stable polymorph at room temperature (RT). Nevertheless, the cubic phase can be stabilized at RT by supervalent partial substitution of Li, La, or Zr.
Here, we have synthesized cubic LLZO garnets stabilized through the partial substitution of Li+ with Fe3+ and studied its electrochemical properties in a symmetrical Li cell. We measured a high total Li-ion conductivity of 1.1 mS cm-1 at RT, as well as an area specific resistance (ASR) of about 1 kΩ cm2. At the interface a black surface coloration was observed after removing the Li metal indicating interfacial degradation. Therefore, we studied the cross section of the interface by using powder XRD, Raman spectroscopy, EDS-SEM, and nano-second laser induced breakdown spectroscopy to identify the origin of the color change and the high ASR. Finally, we identified a 130 μm thick tetragonal LLZO inter-layer as possible explanation by mapping the cross section of the interface by Raman spectroscopy. Most interestingly this interlayer suffer from significant Li deficiency of about 1-2 formula units. Such deficiency could be explained by structural decomposition forming extra phases; however such phases were not observed by Raman spectroscopy or XRD. Based on electron spin resonance spectroscopy the origin of the black coloration was assigned to oxygen trapping in the surface-near garnet lattice.
[1] Murugan, R.; Thangadurai, V.; Weppner, W. Angew. Chem. 2007, 119, 7925.
[2] Awaka, J.; Kijima, N.; Hayakawa, H.; Akimoto, J. J. Solid State Chem. 2009, 182, 2046.
[3] Awaka, J.; Takashima, A.; Hayakawa, H.; Kijima, N.; Idemoto, Y.; Akimoto, J. Key Eng. Mater. 2011, 485, 99.
8:00 PM - ES04.19.76
Electrocatalytic Performance of Cu Bulk Electrodes Annealed under Different Conditions—Evidence of the Role of Cu2O towards CO2 Reduction
Osmando Lopes 1 , Hamiton Varela 1
1 , Institute of Chemistry of São Carlos, University of São Paulo, Sao Carlos Brazil
Show AbstractDevelop technologies that use renewable energy to convert waste such as carbon dioxide (CO2) into hydrocarbon fuels is an urgent requirement. CO2 can be electrochemically reduced to hydrocarbons over Cu electrodes, although higher efficiency and selectivity is still required. It has been reported that the Faradaic efficiencies for this reaction are strongly affected by pretreatment of the Cu electrode and the presence of Cu2O layer. However, the influence of these parameters at Cu electrodes towards the CO2 reduction reaction (CO2RR) are still not clearly established.1,2
Herein we evaluated the effect of heat treatment at Air and H2 atmospheres on Cu bulk (plates) for CO2RR. The Cu plates were electropolished in H3PO4 (Cu-P), and electropolished followed by a heat treatment at 500°C for 12h in Air (Cu-Air) or H2 (Cu-H2).
The X-ray diffraction pattern of Cu-P and Cu-H2 exhibited peaks that can be assigned to cubic phase of metallic Cu (PDF: 85-1326), while the Cu-Air exhibited peaks attributed to metallic Cu and cubic phase of Cu2O (PDF: 65-3288). The Cu-Air electrode showed lower overpotentials on CO2RR, besides a cathodic current higher than that for the Cu-P electrode and Cu-H2. To confirm the CO2RR was performed a chronoamperometry at -1.3 V (vs Ag/AgCl) for 16h, an aliquot was analyzed by high-performance liquid chromatography. All electrodes formed only formate (HCOO-) in liquid phase, confirming that the electrodes were active in CO2 reduction. The Cu-Air electrode produced 480 mg.L-1 of HCOO-, while the Cu-P and Cu-H2 electrode produced 25 and 58 mg.L-1, respectively. Further, the Cu-Air electrode exhibited a Faradaic efficiency (FE) of approximately 43%, while the Cu-P and Cu-H2 exhibited a FE of 16% and 23% at CO2 to HCOO-, respectively. The increase in KHCO3 concentration increase the HCOO- formation for 849 mg.L-1 and efficiency faradaic for 52%, probably due to the increase in the buffering effect near to Cu-Air electrode.3 Gas chromatography analysis exhibited that CO, C2H6, C2H4 and H2 were formed by the Cu-Air electrode.
The activity of Cu-Air electrode was decreased during CO2 reduction, the XRD and XPS analysis after reaction show that Cu2O was completely reduced. Further, the study under galvanostatic conditions (-5 mA.cm-2 for 12 h) with Cu-Air and Cu-P electrodes produced 306 and 124 mg.L-1 of HCOO-, respectively. However, the mechanism of increase in local pH due to high current densities on the highly roughened surfaces do not play a pivotal role as proposed. Therefore, it can be concluded that the heat treatment at oxidant condition on Cu electrode increase its electrocatalytic activity and FE for CO2RR mainly due to the presence of Cu2O layer.2
Acknowledgments:
We thank Brazilian agencies: FAPESP (#16/09746-3), CNPq, and Capes.
References:
[1] H. Mistry et. al, Nat. Rev. Mater. 1 (2016) 16009-16023.
[2] C. W. Li, et. al, Nature, 508 (2014) 504-507
[3] N. Gupta et. al, . J Appl Electrochem 36 (2006) 161-172.
Symposium Organizers
Cengiz Ozkan, University of California, Riverside
Ali Coskun, Korea Advanced Institute of Science and Technology
Ekaterina Pomerantseva, Drexel University
Federico Rosei, Université du Quebec
ES04.20: Li-Ion Batteries
Session Chairs
Friday AM, December 01, 2017
Hynes, Level 3, Ballroom A
8:00 AM - ES04.20.01
Investigating Charging Behaviour Using Instrumented Lithium Batteries
Rohit Bhagat 1 , Tazdin Amietszajew 1 , Joe Fleming 1 , Euan Mcturk 1
1 , University of Warwick, Coventry United Kingdom
Show AbstractDefect propagation and material degradation affect both the performance and safety of energy storage systems. Both processes may accompany operation over time, be nucleated during manufacturing, or be initiated rapidly by external stimuli. This raises particular concerns in lithium-ion cell technologies, where the consequences of faults can be dramatic. However, to date, we have limited capability to detect and/or predict these critical lifetime- and reliability-determining events, especially during operation under real-world operating conditions.
In this paper we present our work related to embedding sensors within and around commercially available pouch and cylindrical format cells. The types of sensors include reference electrodes for measuring half cell voltages during operation, optical fibres to measure mechanically and thermally induced strain, and magnetoresistive sensors to measure the local magnetic field resulting from the flow of charge. Embedding of these sensors is not trivial as the performance of the cell must be unaffected by the modifications. Furthermore, the embedded sensors must survive the cells internal environment. Methodologies for embedding sensors in pouch and cylindrical cells are discussed.
These instrumented cells collectively provide a powerful suite of in-situ and in-operando diagnostics for assessing performance, detecting defect propagation and materials degradation. These diagnostic methods are of great academic interest allowing ageing and failure mechanisms to be studied in greater detail. Furthermore, such diagnostic methods would also be useful in industry allowing systems reliant on lithium battery technology to be characterised in relation to battery operation. Here we present examples of the use of instrumented cells to understand the changes occurring within the cells when operated outside manufacturers’ guidelines and under abuse conditions. Data showing progression of failure is also presented.
8:15 AM - ES04.20.02
Scalable Dry Printing Manufacturing to Enable Long Life and High Energy Lithium-Ion Batteries
Yangtao Liu 1 , Jin Liu 1 , Brandon Ludwig 2 , I-Meng Chen 2 , Heng Pan 2 , Yan Wang 1
1 , WPI, Worcester, Massachusetts, United States, 2 , Missouri University of Science and Technology, Rolla, Missouri, United States
Show AbstractThe conventional slurry casting method dominates the electrodes’ manufacture of lithium ion batteries, which requires a sequence of long-time and complicated procedures. There exists a main concern of the slurry cast manufacturing that the use of an organic solvent (N-methyl-2-pyrrolidone ) is indispensable, which is toxic and high cost but is necessary to fluidize the material mixture into the slurry. To overcome this limitation, additive manufacture was applied here in our dry printing technology to produce electrodes of the lithium-ion batteries. The addictive manufacture technology has been proved to be attractive and competitive in many industries for its unique capability on material loading and layout control. With this dry printing technology, we are able to address a direct drying printing of electrodes onto the current collectors without using solvent at a low cost and high production efficiency. The dry printed electrodes outperform the regular slurry cast ones in many aspects. From our current research, the printed electrode has 80% capacity retained in 500 cycles, which surpass the slurry cast electrode for comparison. In addition, dry printing technology can achieve the design of thickness up to 200μm. For the microstructure of electrodes, PVDF works like glue to attach the particles together between the active materials. The hot rolling procedure can strengthen the bonding and improve the combination in the printed electrodes by promoting the distribution of PVDF. Along with better electrochemical and physical properties, dry printing method could reduce 20% of the cost during the production of electrodes and has the potential for further design.
8:30 AM - ES04.20.03
Bulk and Surface Modification of Li2MnO3 Cathode Materials for Li-Ion Batteries
Leah Nation 1 , Yan Wu 2 , Xingcheng Xiao 2 , Bob Powell 2 , Brian Sheldon 1
1 , Brown University, Providence, Rhode Island, United States, 2 , General Motors, Warren, Michigan, United States
Show AbstractHE-NMC materials, which are comprised of trigonal LiTMO2 (TM = transition metal) and monoclinic Li2MnO3 phases, are of great interest as promising high capacity cathode materials for Li-ion batteries1. However, their structural stability during cycling remains one of the biggest challenges for the application of HE-NMC materials2,3. To understand and address the structural stability issue of HE-NMC material, we studied pure Li2MnO3 material, which is believed to be the component causing the structural transformation during cycling. Systematic XRD, Raman spectroscopy and impedance measurements at varying states of charge were used to fully characterize the layered to spinel phase transition as well as surface reactions during electrochemical cycling. Acid treatment was employed to independently control the creation of oxygen vacancies through chemical activation. Additionally, Al2O3 and LiNbO3 surface coatings were ALD-applied to the Li2MnO3 material. Although the resistance of surfaced coated materials increases, the coating helps with long-term cycling of the Li2MnO3 material when an electrolyte additive is used. These results shed light on the structural evolution during Li2MnO3 cycling and may lead to the development of improved Li2MnO3-LMO2 based batteries.
1. Thackeray, M. M. et al. Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries. J. Mater. Chem. 17, 3112 (2007).
2. Rana, J. et al. Structural Changes in a Li-Rich 0.5Li 2 MnO 3 * 0.5LiMn 0.4 Ni 0.4 Co 0.2 O 2 Cathode Material for Li-Ion Batteries: A Local Perspective. J. Electrochem. Soc. 163, A811–A820 (2016).
3. Armstrong, A. R. et al. Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode Li[Ni0.2Li0.2Mn 0.6]O2. J. Am. Chem. Soc. 128, 8694–8698 (2006).
8:45 AM - ES04.20.04
Pomegranate–Structure Silicon/carbon Mesoporous Composite as High–Performance Anode for Lithium–Ion Batteries
Tong Shen 1 , Xinhui Xia 1 , Xiuli Wang 1 , Jiangping Tu 1
1 , School of Materials Science and Engineering, Zhejiang University, Hangzhou China
Show AbstractIt is a research hotspot to develop advanced anode with high capacity and good high–rate cycles for lithium–ion batteries. Silicon (Si), one of the most promising candidates for next generation anode material, has received extensive consideration due to its ultrahigh theoretical capacity (∼ 4200 mAh g–1), low working potential and natural abundance. However, the tremendous volume expansion during lithiation/delithiation processes and low intrinsic electronic conductivity are still main obstacles hindering the further commercial applications of Si–based electrode.
To address these drawbacks, in this work, we proposed a facile way to design and fabricate a novel silicon/carbon mesoporous spherical composite via one–step hydrothermal method. Importantly, Si nanoparticles of 50-100 nm are directly embedded into the mesoporous carbon matrix forming a pomegranate-structure configuration. The entirely encapsulated carbon matrix not only serves as an effective buffer to large volume change but also works as a highway conductive channel, leading to the enhanced structural stability and electron transfer. As a result, much–improved cycle stability with an encouraging capacity retention of 77% at 0.2 A g–1 after 100 cycles and a superior rate capacity have been obtained. This unique synthesis strategy provides a new way for low cost and mass production of high-performance anodes in lithium–ion batteries.
9:00 AM - ES04.20.05
An All-Solid-State Thin-Film Li-Garnet Microbattery—Composed of Li7MnN4 Anode, Ni0.8Co0.15Al0.05O2 Cathode and Li6.25Al0.25La3Zr2O12 Electrolyte Films
Reto Pfenninger 1 2 , Michal Struzik 1 2 , Inigo Garbayo 2 , Andreas Nenning 2 1 , Jennifer Rupp 2 1
1 DMSE, MIT, Cambridge, Massachusetts, United States, 2 D-MATL, ETH Zürich, Zurich Switzerland
Show AbstractAmong the different all-solid state electrolytes available today1 (e.g.NASICON2, LISICON3 or LIPON4) cubic garnet Li7La3Zr2O12-based structures5 are of particular interest. Firstly reported by Weppner et al.6, Li7La3Zr2O12 (LLZO) with fast Li+-conduction of up to 1x10-3 Scm-1 has been reported at ambient temperature5 that positions the garnets as one of the highest solid-state inorganic Li+ conductors available. Despite the progress on LLZO as a solid state electrolyte only few systematic studies have been conducted on the combination of electrodes with Li7La3Zr2O12 electrolytes, so far; viz. the chemical stability and operation conditions of full LLZO-based battery cells are still under discussion. Regarding thin films, several attempts have already been conducted on pulsed laser deposition (PLD) and investigation of cathodes for Li-garnet electrolytes: i.e. LiCoO2 cathodes, see Asaoka group.7–10. In this work, a fully thin film stacked microbattery is presented in combination with thin film Li6.25Al0.25La3Zr2O12 electrolyte for the first time. In that sense, we extend the fabrication of all-solid-state Li-ion batteries combining the rather unusual anode material Li7MnN4, as well as Ni0.8Co0.15Al0.05O2 cathode in the form of thin film with the Li-garnet electrolyte Li6.25Al0.25La3Zr2O12. We demonstrate composition control and deposition of dense and crack-free thin films of all three battery components, as well as separate growth on single crystalline substrates. Raman and electrochemical impedance spectroscopic techniques are employed to investigate the impedances relative to the nanostructure and phase for the anode and cathode thin film. Specific capacities of 0.08 µAhcm-2µm-1 could be obtained with stable cycling conditions. The presented full Li-microbattery concept contributes to efforts understanding the Li-charge transfer at the interfaces and also to potential future full solid state Li-film microbattery concepts as units in portable electronics.
References
1.Knauth, P.Solid State Ion. 180, 911–916 (2009).
2.Hartmann, P. et al. J. Phys. Chem. C 117, 21064–21074 (2013).
3.Kobayashi, T. et al. J. Power Sources 182, 621–625 (2008).
4.Nimisha, C. S., Rao, G. M., Munichandraiah, N., Natarajan, G. & Cameron, D. C.Solid State Ion. 185, 47–51 (2011).
5.Thangadurai, V., Narayanan, S. & Pinzaru, D. Chem. Soc. Rev. 43, 4714 (2014).
6.Murugan, R., Thangadurai, V. & Weppner, W. Angew. Chem. Int. Ed. 46, 7778–7781 (2007).
7.Ohta, S., Kobayashi, T. & Asaoka, T. J. Power Sources 196, 3342–3345 (2011).
8.Ohta, S., Kobayashi, T., Seki, J. & Asaoka, T. J. Power Sources 202, 332–335 (2012).
9.Ohta, S. et al. J. Power Sources 238, 53–56 (2013).
10.Ohta, S. et al. J. Power Sources 265, 40–44 (2014).
9:15 AM - ES04.20.06
A Highly-Efficient Route to PVDF-HFP Separator Embedded with Colloidal TiO2 Nano-Crystals towards High-Temperature Lithium-Ion Batteries
Weidong He 1 , Weiqiang Lv 1 , Jiangwei Li 1
1 , University of Electronic Science and Technology of China (UESTC), Chengdu China
Show AbstractPVDF-HFP/colloidal-TiO2 composite separator is realized, for the first time, towards high-temperature lithium ion batteries. Colloidal TiO2 introduced into the PVDF-HFP matrix not only allows for the formation of a highly-uniform composite micro-structure, but also reduces the crystallinity of PVDF-HFP. Consequently, the separator exhibits substantially-enhanced mechanical robustness and electrolyte uptake. In particular, the as-prepared separator owns advantageous stability even upon thermal treatment at 165 oC. With a high ionic conductivity up to 1.57 × 10-3 S cm-1, the LFP/Li cell with PVDF-HFP/colloidal-TiO2 composite separator illustrates good charge-discharge performance with 156.95 mAh g-1 (0.1 C) at room temperature and 120.8 mAh g-1 (0.5 C) with pronounced stability of 99% capacity retention after 100 cycles when annealed at 140 oC for 3 hours. Such reported PVDF-HFP/colloidal-TiO2 separator demonstrates promising potentials for practical applications in high-temperature environments.
9:30 AM - ES04.20.07
Single-Particle Performances and Properties of LiFePO4 Nanocrystals for Li-Ion Batteries
Jiangtao Hu 1 , Wen Li 1 , Yuan Lin 1 , Feng Pan 1
1 , Peking University, Shenzhen China
Show AbstractUnderstanding the fundamental electrochemical properties of electrode materials is important to improve the performance of Li-ions batteries. However, most of previous tests on a thick electrode or full battery can only reflect the overall characteristics of the working electrode or the properties of the collective particles and can’t get the intrinsic properties of a single nano-particle. Here, we investigate the intrinsic properties and performances of the single-particle (SP) of LiFePO4 by developing the SP electrode and creating the SP-model, which would share deep insight on how to further improve the performance of the electrode and related materials. The SP electrode was generated by fully scattering and distributing LiFePO4 nano-particles to contact with the conductive network of carbon nanotube or conductive carbon to demonstrate the sharpest cyclic voltammetry peak and related SP-model was developed, by which we find that the interfacial rate constant in aqueous electrolyte is one order of magnitude higher, accounting for the excellent rate performance in aqueous electrolyte for LiFePO4. We propose for the first time that the insight of pre-exponential factor of interface kinetic Arrhenius equation is related to de-solvation/solvation process. Thus, this much higher interfacial rate constant in aqueous electrolyte should be attributed to the much larger pre-exponential factor of interface kinetic Arrhenius equation, because the de-solvation process is much easier for Li-ions jumping from aqueous electrolyte to the Janus solid-liquid interface of LiFePO4.
9:45 AM - ES04.20.08
Silicon-Carbon Nanocomposite Anode Material for Lithium-Ion Batteries
Parham Rohani 1 , Adam Raszewski 1 , Gang Wu 1 , Mark Swihart 1
1 , State University of New York at Buffalo, Buffalo, New York, United States
Show AbstractSilicon is one of the best anode materials for lithium-ion batteries. It has exceptionally high theoretical specific and volumetric capacities of 4200 mAh/g and 9786 mAh/cm3, respectively. Its theoretical gravimetric capacity is more than 10 times that of graphite. High abundance, low toxicity, and availability of large-scale production methods also make silicon an ideal material for battery applications. However, practical use of silicon as an anode material has been limited by very poor cycling performance. The huge volume changes of silicon (>300%) upon lithiation and delithiation lead to mechanical failure, pulverization of the silicon itself, and disruption of the solid-electrolyte interface (SEI) layer. Repeated fracturing of the silicon and re-growth of the SEI rapidly degrade capacity and performance. Use of nanoscale or nanostructured silicon can reduce pulverization and mechanical stress due to lithiation and delithiation, because nanosized structures can accommodate significant greater stress and strain without fracturing, compared with bulk silicon. Furthermore, nanoscale silicon increases the surface area accessible to the electrolyte while decreasing electronic and ionic transport distances, improving rate capabilities. However, limited electrical conductivity and disruption of the SEI can severely limit the performance of even nanostructured silicon electrodes. One strategy to eliminate these effects is to encapsulate silicon within structures that can accommodate silicon volume changes during lithiation and delithiation. While such “yolk-shell” and “pomegranate” type structures have been demonstrated and have shown promise, urgent needs remain for improved performance, which may be achievable by using smaller silicon structures, and for more practical processes for producing such structures at large scale and acceptable cost. In this study, we synthesized silicon nanoparticles with the primary size of 20 nm via laser-induced pyrolysis of silane. We then employed a combination of wet chemistry and gas phase processes to encapsulate these silicon nanoparticles within a network of carbon shells, with void space surrounding each silicon particle. The carbon coating provides electrical conductivity and may promote formation of a stable SEI, while the void spaces within the nanocomposite structure accommodate volume changes during lithiation and delithiation. The thickness of the carbon layer and its permeability to lithium ions must be controlled to maximize performance. We prepared anodes with these materials, using binders such as CMC, PAA, and PVDF, and tested their performance. We compare their performance to that of similar structures prepared using larger silicon particles (~100 nm) and to anodes prepared without carbon coating.
ES04.21: Other Battery Materials IV
Session Chairs
Friday PM, December 01, 2017
Hynes, Level 3, Ballroom A
10:30 AM - *ES04.21.01
Molecular Polymer-Derived Ceramics for Applications in Electrochemical Energy Storage Devices
Gurpreet Singh 1
1 , Kansas State University, Manhattan, Kansas, United States
Show AbstractMolecular precursor derived ceramics (PDCs) have garnered intense research interest as potential standalone as well as composite electrode materials for rechargeable alkali metal-ion batteries and supercapacitors. PDC based electrodes offer high surface area, improved electrical conductivity and mechanical strength along with added value of mass production. Here, we will present data on recent success in synthesis of composites molecular precursor-derived silicon oxycarbide (SiOC), and chemically modified graphenes. We will show that interfacing PDCs with graphene derivatives is an effective strategy in improving PDC’s Li-ion electrochemical capacity, first cycle efficiency, and long- term cyclability. Flexible, lightweight, and mechanically robust nanostructured electrodes deliver Li- capacity of approximately 550 mAh/g (total electrode weight) with nearly 100 % coulombic efficiency for over 1000 cycles. In addition, we will discuss the role of thermal annealing on electrical conductivity and capacitance effect in SiOC electrodes.
11:00 AM - ES04.21.02
Nanostructured Cathode and Anode Materials for Mg-Ion Batteries
Kostiantyn Kravchyk 1 2 , Maryna Bodnarchuk 2 , Maksym Kovalenko 1 2
1 Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich Switzerland, 2 Laboratory for Thin Films and Photovoltaics, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf Switzerland
Show AbstractDue to limited natural abundance of lithium, novel battery technologies are needed for large-scale, stationary storage of electricity.1 Such batteries can then be combined with renewable sources of electricity, for the best integration of a variety of sources into electrical grid. We will discuss the utility of nanoscale inorganic materials as cathode and anode materials in Mg-ion batteries. In particular, the focus will be on a balance between the performance, material’s synthesis costs and natural abundance of the constituting elements. Owing to the reduced diffusivity of Mg-ions in most materials, nanostructuring has been identified to be of drastically higher importance than in the case of alkali-ion (Li, Na) batteries. The cathodic side of a battery remains the bottleneck. In this regard, we present several metal sulfides, delivering capacities of up to 160 mAh g-1, with plateau voltages of 1.1-1.2 V.2 On the anode side, we present Bi nanostructures as convenient anodes for research purposes. In particular, Bi-based anodes operate in a variety of electrolytes, in which metallic Mg is non-operational due to oxidative passivation.3
References
[1] H.D. Yoo, et al. Energy & Environmental Science, 2013, 6, 2265-2279.
[2] K.V. Kravchyk, et al. ASC Nano, 2017, in preparation.
[3] K.V. Kravchyk, et al. Chemistry of Materials, 2017, in preparation.
11:15 AM - ES04.21.03
Effect of Renormalization Due to Dynamic Surface Polarization on the Oxidative Stability of Solvents in Nonaqueous Li-O2 Batteries
Abhishek Khetan 1 2 , Heinz Pitsch 2 , Venkatasubramanian Viswanathan 1
1 , Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 2 , Institute for Combustion Technology RWTH, Aachen Germany
Show AbstractA molecule's frontier orbital energy levels can be dynamically influenced by the polarizability of its local electrochemical environment, as is evident from photoemission and electron transport measurements1 and many body calculations2,3. These effects can drastically alter the propensity of charge transfer between the molecule and the electrode surfaces, and thus accounting for this renormalization is of utmost importance in the context of the nonaqueous Li-O2 battery, where the oxidation of the electrolyte is known to be extremely detrimental to its rechargeability4. In this work, we address in detail the influence of interfacial interactions on the electrochemical stability of nonaqueous solvents by providing an accurate description of the molecular energy levels of the solvents as well as the electrode surfaces using high fidelity GW calculations.
We systematically study how the electronic energy levels of four commonly used solvent molecules, namely dimethylsulfoxide (DMSO), dimethoxyethane (DME), tetrahydrofuran (THF) and acetonitrile (ACN), renormalize when physisorbed on the different stable surfaces of Li2O2, the main discharge product. Using band level alignment arguments, we propose the difference between the renormalized highest occupied molecular orbital (HOMO) level and surface valence band maximum (VBM) energy level, instead of the absolute renormalized HOMO level of the solvent molecule, as a refined metric of oxidative stability. This metric and the previously employed solvent's gas phase HOMO level, are found to agree quite well for physisorbed cases on the insulating 1-100 termination of Li2O2 where ACN is oxidatively most stable followed by DME, THF and DMSO. The renormalization of solvents' HOMO-LUMO levels was found to be much more evident over the metallic 0001 surface, with DME instead of ACN, emerging as the most stable solvent molecule against oxidation.
We further demonstrate that this effect is intrinsically linked to the surface chemistry of the solvent's interaction with the surface states, its defects and stoichiometry. We conclusively show that the propensity of solvent molecules to oxidize will be significantly higher on Li2O2 surfaces with defects as compared to pristine surfaces. This suggests that the oxidative stability of a solvent is a dynamic function of surface electronic properties. While gas phase HOMO levels could be used for preliminary solvent screening, a more refined picture of solvent stability requires mapping it out as a function of the state of the surface under operating conditions.
References:
1 J. Repp, G. Meyer, S. M. Stojkovic, A. Gourdon, C. Joachim, Phys. Rev. Lett. 94, 026803 (2005)
2 J. Neaton, M. Hybertsen, S. Louie, Phys. Rev. Lett. 97, 216405 (2006)
3 J. M. Garcia-Lastra, C. Rostgaard, A. Rubio, K. S. Thygesen, Phys. Rev. B 80, 245427 (2009)
4 A. Khetan, H. Pitsch, V. Viswanathan, J. Phys. Chem. Lett. 5, 1318 (2014)
11:30 AM - ES04.21.04
Electrochemical Characterization of Electrodeposited MoS2 Battery Electrode
Ruhul Amin 1
1 Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Education City, Doha Qatar
Show AbstractThe MoS2 is used in diverse field of applications including rechargeable battery and solar cell, hydrogen storage, electronic transistors and catalysis. The ionic diffusivity and interfacial exchange current density, are model parameters, play an important role for the optimization of device performances which are not clearly known for this material. Additive-free dense film of MoS2 has been fabricated by electrodeposition technique and heat treated at different temperatures in argon atmosphere. The resulted film is characterized by XRD, SEM, AFM and XPS. The measurements of interfacial charge transfer kinetics and lithium ion (sodium ion) diffusivity is performed in the fabricated film A1-xMoS2 (A= Li, Na) as a function of lithium (sodium) content at ambient temperature. The exchange current density at the electrode/electrolyte interface is found to be almost invariable with the degree of lithiation (sodiation) (~0.09-0.08mA/cm2) at (x=0.01-0.20). The ionic diffusivity of the phase is found to be ~5x10-12cm2s-1 and ~5x10-11cm2s-1, respectively, and does not vary much with the degree of lithiation (sodiation) in the measured concentration window. From the obtained results it appears that the charge transfer resistance during electrochemical use is limited by the interfacial kinetics over the measured state-of-charge. Nano scale particle with high surface area is needed to be used as a battery electrode of the material for practical C-rates.
11:45 AM - ES04.21.05
The Influence of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries
Antoni Forner-Cuenca 2 1 , Fikile Brushett 2 1
2 , Joint Center for Energy Storage Research, Argonne, Illinois, United States, 1 Chemical Engineering Department, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States
Show AbstractRedox flow batteries (RFBs) are promising rechargeable electrochemical devices for grid-scale energy storage but further cost reduction is needed for ubiquitous adoption of this technology. While current state-of-the-art RFB systems employ aqueous chemistries, transitioning to nonaqueous electrolytes offer a new pathway to reduced cost through increased energy density. While research efforts have primarily focused on molecular discovery1, there has been significantly less attention paid to the development of other critical system components. Of particular importance are the porous electrodes used in the RFB’s electrochemical stack. Though current generation electrodes largely draw from the fuel cell material set, within a RFB, the porous electrode must perform a range of different roles including serving as active surfaces for electrochemical reactions, enabling excellent liquid electrolyte distribution, and maintaining low pressure drops. Thus, to enable the development of advanced electrodes tailored for RFB applications, it is necessary to quantify the performance-limiting factors for the present materials set. However, unambiguous analysis is challenging in an operating RFB due to the complex coupling of transport and reactions which changes as a function of state of charge during cell cycling. Thus, deconvoluting the role of electrode properties on flow battery performance requires the development of diagnostic techniques that enable individual electrode characterization in isolation, but at near, practical operating conditions.
To this end, we systematically compare the operando performance of RFBs containing selected carbon paper, felt, and cloth electrodes using the single-electrolyte cell configuration2 and a model organic redox couple (TEMPO/TEMPO+). Using polarization and electrochemical impedance spectroscopy, we quantify the impact of electrode microstructure on battery performance. We find that, depending on the electrode choice and flow conditions, current densities as high as 450 mA cm-2 can be achieved at an overpotential of 0.3 V with a cell area specific resistance as low as 0.7 Ω cm2. Our results suggest that high power performance is possible in nonaqueous flow batteries. Finally, a simple convection-diffusion mass transport model is developed to explain the observed experimental behavior and provide guidance for the design of next generation RFB electrodes.
1. F. R. Brushett et al., Adv. Energy Mater., 2, 1390 (2012).
2. R. Darling et al., J. Electrochem. Soc., 161, A1381 (2014).
Acknowledgments
We gratefully acknowledge the financial support of the Swiss National Science Foundation (P2EZP2_172183) and the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the United States Department of Energy.
ES04.22: Electrode Materials IV
Session Chairs
Francesca Iacopi
Guiliang Xu
Friday PM, December 01, 2017
Hynes, Level 3, Ballroom A
1:30 PM - ES04.22.01
Activated Carbons from Biopolymers as Electrode Materials in Various Electrochemical Systems
Ilona Acznik 1 , Katarzyna Lota 1 , Agnieszka Sierczynska 1
1 , Institute of Non-Ferrous Metals Division in Poznan, Poznan Poland
Show AbstractCarbonaceous materials are well known and readily used in a broad range of applications. Owing to the well-developed porous structure and the presence of certain surface functional groups, these materials are commonly used as adsorbents for a wide range of contaminants from gaseous or liquids media. Currently, activated carbons are also widely used as the electrodes for electric double-layer capacitors because of their high surface area, chemical stability and acceptable price.
This work is focused on the carbon materials obtained from biopolymers such as lignin, cellulose and chitosan as precursors. The carbonisation in nitrogen atmosphere followed by chemical activation in KOH was chosen as a synthesis method. The resulting carbon materials were characterised by well-developed surface area and microporous structure, beneficial for electric double-layer capacitors (EDLC) electrodes. In parallel, graphene-like materials obtained from graphite oxidation followed by thermal reduction were also synthesised.
The main goal of performed research tasks was to compare the electrochemical properties of carbon materials applied as electrode materials in different energy storage systems - electrochemical capacitors and in hydrogen storage systems. The special example taken into the consideration were hybrid capacitors composed of a battery-type electrode and a high surface area carbon electrode. This kind of configuration allows merging the advantages and reduces the drawback of redox and capacitive based systems. Since the same electrode material can give different electrochemical response depending on the type of device in which they are employed, this work will report on the influence of the physicochemical properties of carbon-based electrodes of various origin on their electrochemical response in various energy storage systems.
1:45 PM - ES04.22.02
Catalytic Conducting Polymer Electrodes in Biofuel Devices
Keiichi Kaneto 1 , Mao Nishikawa 1 , Sadahito Uto 1
1 Department of Biomedical Engineering, Osaka Institute of Technology, Osaka Japan
Show AbstractBiofuel cells are interested and studied intensively in these decades, because they are renewable and sustainable electrical energy sources. However, most of high power fuel cells are fabricated by use of catalytic rare metals like Pt, Pd and etc. These metals are expensive, which discourages from development and wide usage of biofuel cells. Conducting polymers have been utilized in biofuel cells to enhance the charge transfer rate from biofuel to electrode, namely as the mediator. However, the catalytic activity of conducting polymers has not been known.
We have been studying catalytic activity of conducting polymers in direct and passive biofuel cells, in comparison with the performance of biofuel cells utilizing catalysis of Pt-black/carbon powder. The cells with structure of Biofuel/anode/Nafion/cathode/Air were fabricated. The anode and cathode are polyaniline (ES; emeraldine salt) or Pt-Black (1 mg/cm2) on carbon sheet. A 0.5 M L-ascorbic acid was used as the biofuel, and the Nafion was served as a proton transfer membrane. In the standard Pt catalysis cell, the typical Voc (open circuit voltage) = 0.46 V and Isc (short circuit current) = 6 mA/cm2 and the maximum power density of approximately 1 mW/cm2) were obtained. The cell performance of ES anode exhibited approximately a third of the standard Pt catalysis cell. The cell with PANi ES cathode showed a fourth of standard Pt catalysis cell.
Biofuel cells using conducting polymers are aimed to replace Pt-catalysis and reach to the performance comparable to the cell with Pt catalysis. Further development of biofuel power cells using conducting polymers will be reported.
2:00 PM - ES04.22.03
Divulging the Hidden Capacity, Sodiation Kinetics and Interfacial Effect of NaxC6Cl4O2—A High Voltage Organic Cathode for Sodium Rechargeable Batteries
Amitava Banerjee 1 , Rafael Araujo 1 , Rajeev Ahuja 1
1 Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Uppsala Sweden
Show AbstractOn the most emerging sustainable rechargeable organic battery field, quinones stand up as one of the prime candidates for the application in battery electrodes. Recently, C6Cl4O2, a modified quinone, called chloranil has been proposed as a high voltage organic cathode. However, the sodium insertion mechanism behind the cell reaction of chloranil remained unclear due to the nescience of right crystal structure. Here, the framework of the density functional theory (DFT) together with an evolutionary algorithm was employed to elucidate the crystal structures of the compounds NaxC6Cl4O2 (x=0.5, 1.0, 1.5 and 2). Along with the usefulness of PBE functional to reflect the experimental potential, also the importance of the hybrid functional to divulge the hidden theoretical capacity is evaluated. We showed that the experimentally observed lower specific capacity is a result of the great stabilization of the intermediate phase Na1.5C6Cl4O2. The calculated activation barrier for the ionic hop is 0.68 eV, 0.40 eV and 0.31 eV, respectively for NaC6Cl4O2, Na1.5C6Cl4O2 and Na2C6Cl4O2. These results indicate that the kinetic process must not be a limiting factor upon Na insertion. As per our knowledge, this is the first time, analyzing interfacial effect of chloranil on the electrochemical properties. Here we have considered most stable surface to investigate the ionic as well as electronic transport in presence of acetonitrile as an example of electrolyte.
Finally, the correct prediction of the specific capacity has confirmed that the used theoretical strategy, employing evolutionary simulations together with the hybrid functional framework, can rightly model the thermodynamic process in organic electrode compounds. Then at the end, using this theoretical methodology, we have shown the importance interfacial effect on the electronic and ionic transport.
2:15 PM - ES04.22.04
Ab Initio Modeling of the Electronic Properties of Lithiated Anode Materials
Dominik Bauer 1 , Teutë Bunjaku 1 , Andreas Pedersen 2 , Mathieu Luisier 1
1 , ETH Zürich, Zürich Switzerland, 2 , Technical University of Denmark, Copenhagen Denmark
Show AbstractRenewable energy sources such as solar or wind are expected to become key suppliers in the near future and to replace fossile fuels. For this revolution to happen, highly efficient and large-scale energy storage methods are required, a role that the Li-ion battery (LIB) technology could play, as successfully demonstrated within the electronic industry [1]. However, the battery performance with respect to the energy and power capacity as well as its lifetime must still be improved to reach this objective. Further research is therefore necessary to study alternative electrode materials, which can be done via computer simulations.
SnO and Si are strong contenders to the most widely used anode material, graphite. They outperform the latter by more than a factor two in terms of the storage capacity, but their practical implementation comes with a prohibitive volume expansion during the lithiation process [1]. One approach to overcome the resulting performance degradation consists in patterning these materials into nanostructures [1]. At this scale, structural variations have a less negative impact, but both the ion and electron motions must be described at a quantum mechanical level to correctly capture the underlying physics. This work concentrates on the modeling of the electronic and thermal properties of nanostructured SnO- and Si-based anodes as they strongly affect the efficiency of the battery charge and discharge processes.
Ab-initio simulations have become a well-established approach to study the structural characteristics of LIBs [2]. The increasing availability of computing power and the development of advanced algorithms have made this possible. Our approach relies on density-functional theory, a transformation of the plane-wave outputs into a set of maximally localized Wannier functions, the construction of a tight-binding-like Hamiltonian matrix that corresponds to the desired anode structure, and finally the simulation of quantum transport within the non-equilibrium Green's function formalism. This combination of various methods and tools does not only allow to compute the total current flowing through the considered atomic systems but also its spatial distribution, thus shedding light on the interplay between the atomic fitting and the preferred current trajectories as a function of the lithium concentration. Furthermore, with the proposed scheme, it is possible to go beyond the ballistic limit of transport, include electron-phonon scattering, and account for electro-thermal phenomena, e.g. Joule heating. All these effects will be discussed, together with the calculation of the electrical and thermal conductivity of selected anode materials from first-principles, the results can then be used as input parameters for full-scale battery simulations, paving the way for accurate computer-assisted design of LIBs.
[1] C.-M. Park, J.-H. Kim, H. Kim, and H.-J. Sohn, Chem. Soc. Rev. 39, 3115 (2010).
[2] J. Hafner, J. Comput. Chem. 29, 2044 (2008).
2:30 PM - ES04.22.05
Two-Dimensional Transition Metal Carbides (MXenes) as Cathode Materials for Rechargeable Aluminum Batteries
Armin Vahid Mohammadi 1 , Majid Beidaghi 1
1 , Auburn University, Auburn, Alabama, United States
Show AbstractBatteries based on multivalent ions, such as divalent magnesium or calcium ions and trivalent aluminum ion, are among the potential candidates for future cost-effective and high energy density energy storage devices. However, development of multivalent-ion batteries is hindered by the lack of efficient electrolytes and cathode materials for these battery chemistries. Among different multivalent-ion batteries, rechargeable aluminum batteries are promising alternative energy storage devices due to the low cost and abundance of aluminum, and the potential of Al3+ cations to undergo three-electron redox reactions leading to higher capacities. Aluminum has a theoretical volumetric capacity of 8040 mAhcm-3 (four times higher than that of lithium) and a good gravimetric capacity of 2980 mAhg-1. Additionally, aluminum can be handled in open air, supporting easier cell fabrication processes and elimination of some of the safety issues associated with lithium and sodium ion batteries [1]. Various materials have been studied as potential cathode materials for rechargeable aluminum batteries. However, very few intercalation-type cathodes such as V2O5, Chevrel phase (Mo6S8), and TiS2 are known that can host the high charge density Al3+ ions. These materials usually suffer from low capacity, low voltage, and low cycle life with significant capacity decay over 100 cycles. Therefore, high-performance cathode materials that can reversibly intercalate aluminum ions are yet to be found. In this presentation, we report on the performance of two-dimensional (2D) transition metal carbides (called MXenes) as potential intercalation cathode materials for rechargeable aluminum batteries utilizing a room temperature ionic liquid electrolyte. MXenes are a family of 2D transition metal carbides and/or carbonitrides that are produced by selective removal of metal elements (e.g. Al) from MAX phases (e.g. Ti2AlC) [2, 3]. The studied aluminum batteries work by electrochemical deposition and dissolution of aluminum at the anode and intercalation/de-intercalation of Al3+ ions between the layers of 2D MXene nanosheets. Among different studied MXene materials, Ti2CTx (Tx represents functional groups such as O, OH, and F on the surface of MXene sheets) and V2CTx showed distinct charge and discharge plateaus with first discharge cycle capacities as high as 200 mAh/g and 400 mAh/g, respectively at current density of 100 mA/g. The MXene based aluminum batteries were cycled in 1.7 V potential window and showed high Coulombic efficiencies. Our results open a new direction in the search for high capacity cathode materials for aluminum batteries.
Keywords: 2D, Transition Metal Carbides, MXenes, Aluminum battery
References
1. G. A. Elia, et al., Adv. Mater. 28, 7564-7579 (2016).
2. M. Naguib, et al., ACS Nano. 6, 1322–1331 (2012).
3. B. Anasori, M. R. Lukatskaya, Y. Gogotsi, Nat. Rev. Mater. 2, 16098 (2017).
2:45 PM - ES04.22.06
Hybrid Anode Based on SnO2-Co3O4 Nanocubes Entrapped by Ti3C2Tx Nanosheets with Exceptional Lithium Storage
Vincent Ng 1 , Hui Ling Tan 1 , Zhichuan Xu 1 , Hui Huang 2 , Wenxiu Que 3 , Ling Bing Kong 1
1 School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore Singapore, 2 , Singapore Institute of Manufacturing Technologies (SIMTech), Singapore Singapore, 3 Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Electronic Materials Research Laboratory, School of ElectronicXi’an Jiaotong University, Xi’an, P. R. China, Xi'an China
Show AbstractMXenes are promising high rate lithium-ion batteries (LIBs) anode materials, as they embody large electrochemically-active surfaces with excellent electronic conductivity, low operating voltage range and low diffusion barriers albeit moderate capacity. Intuitively, by combination of transition metal oxides (TMOs), with high specific capacity but poor conductivity, composites with enhanced electrochemical performance, exceeding that of Ti3C2Tx or TMO individually, may be achieved.
Adopting the modified procedure with an increased molar ratio of LiF to Ti3AlC2 to 7.5:1 (instead of 5:1), laterally large flakes of exfoliated Ti3C2Tx with minimal defects and improved conductivity are synthetically obtained [1]. SnO2-Co3O4 nanocubes are intentionally selected, as the TMO to couple with Ti3C2Tx, to exploit the synergistic effect of Co nanoparticles, formed by decomposition of Co3O4 during lithiation, improving partial reversibility of the reduction of Li2O formed during conversion reaction of SnO2 [2]. These SnO2-Co3O4 nanocubes can also serve as spacers to improve ions’ accessibility in between the Ti3C2Tx layers.
In this work, we constructed a hybrid composite of SnO2-Co3O4 nanocubes entrapped by Ti3C2Tx nanosheets by using freeze-drying technique and evaluate its performance as a LIBs anode material [3]. Pink CoSn(OH)6 is precipitated by the addition of NaOH to a mixture of SnCl4.5H2O, CoCl2.6H2O and sodium citrate. The composition of SnO2-Co3O4-Ti3C2Tx was also optimized.
1. Shahzad, F., et al., Electromagnetic interference shielding with 2D transition metal carbides (MXenes). Science, 2016. 353(6304): p. 1137-1140.
2. Kim, W.-S., et al., SnO2@Co3O4 hollow nano-spheres for a Li-ion battery anode with extraordinary performance. Nano Research, 2014. 7(8): p. 1128-1136.
3. Guo, J., et al., Flexible foams of graphene entrapped SnO2-Co3O4 nanocubes with remarkably large and fast lithium storage. Journal of Materials Chemistry A, 2016. 4(41): p. 16101-16107.
ES04.23: Other Battery Materials V
Session Chairs
Francesca Iacopi
Guiliang Xu
Friday PM, December 01, 2017
Hynes, Level 3, Ballroom A
3:30 PM - *ES04.23.01
Materials and Interfaces Challenges on Building Advanced Sodium-Ion Batteries
Guiliang Xu 1 , Zonghai Chen 1 , Wenjuan Liu Mattis 2 , Ismael Saadoune 3 , Jones Alami 3 , Khalil Amine 1
1 Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois, United States, 2 , Microvast Power Solutions, Orlando, Florida, United States, 3 , Mohamed VI Polytechnic University, Ben Guerir Morocco
Show AbstractSince first commercialization by Sony Corporation in 1990s, Lithium-ion batteries (LIBs) have dominated the portable electronics markets and are now showing great potential for mid-size applications such as hybrid electric vehicles (HEVs), pulg-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). However, because lithium sources are scarce and discretely located on Earth, the search for novel and more sustainable chemistries for larger scale energy storage systems (ESSs) application is intensified. Room temperature sodium-ion batteries (SIBs) have recently attracted increased attention especially in the grid-scale storage due to the wider availability and lower cost of sodium. To achieve high performance SIBs, smart structure design strategies on advanced high capacity cathode materials and stabilized high capacity anode materials as well as optimum electrode/electrolyte interfaces are needed. In this paper, we report a comprehensive study to elucidate and exemplify the interplay mechanism between phase structures, interfacial microstrain and electrochemical properties of layered-structured SIBs cathodes. We found that intergrowth P2/O1/O3 cathode can inhibit the irreversible P2-O2 phase transformation and simultaneously improve the structure stability of the O3 and O1 phases during high-voltage cycling. We will also describe some new approaches to improve the cycle life of phosphorus-based anode material for sodum ion battery. Phosphorus-carbon composite with a high phosphorus content (70 wt %) could deliver a very high initial Coulombic efficiency (>90%) and high specific capacity with excellent cyclability at high rate of charge/discharge. Mechanism of understanding the electrode/electrolyte interfaces governing the relationship between structure and performance will be also included by using synchrotron X-ray, transmission electron microscopy and Nuclear magnetic resonance spectroscopy study. These findings can provide new guidelines for future design and fabrication of advanced SIBs for larger scale ESSs applications.
References
1. N. Yabuuchi, K. Kubota, M. Dahbi and S. Komaba, Chemical Reviews, 2014, 114, 11636-11682.
2. G. L. Xu, R. Amine, Y.-F. Xu, J. Liu, J. Gim, T. Ma, Y. Ren, C. Sun, Y. Liu and X. Zhang, Energy & Environmental Science, 2017, 10, 1677-1693.
3. G. L. Xu, Z. Chen, G. M. Zhong, Y. Liu, Y. Yang, T. Ma, Y. Ren, X. Zuo, X. H. Wu, X. Zhang and K. Amine, Nano Lett, 2016, 16, 3955-3965.
4:00 PM - ES04.23.02
Hierarchical Carbon-Based Electrocatalyst for High-Power Density Zinc-Air Batteries
Arturo Reza Ugalde 1 , Hani Naguib 1 2 3
1 Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada, 2 Materials Science and Engineering, University of Toronto, Toronto, Ontario, Canada, 3 Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
Show AbstractZn-air batteries have become one of the best candidates for clean, safe and low-cost energy storage devices, gathering multidisciplinary research in order to overcome the problems related to the main battery’s components. Although the Zn-air battery is already on the market, the only available configuration is a coin-type battery with an open circuit voltage (OCV) of 1.4 V and an operation voltage of 1.2 V. Its low kinetics involved in the oxygen reactions limits its range of applications to low power output devices, such as hearing aid batteries. Therefore, there is a need for an efficient electrocatalyst capable of boosting the reaction in both directions, i.e. oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
This work presents a hybrid carbon-based architecture as electrocatalyst for Zn-air batteries, where graphene nanoplatelets (GNPs) are connected through functionalized single-wall carbon nanotubes (SWCNTs), achieving a structure with high electrical conductivity and good electrochemical stability. The SWCNTs were functionalized by acid treatment using sulfuric acid (H2SO4) and nitric acid (HNO3) in a ratio of 3:1. After the acid treatment, the SWCNTs were washed, and three samples with different pH were prepared altogether with the GNPs.
It was found that the pH in the fillers is directly related to the electrochemical stability of the electrocatalyst. Since the functional groups created during the acid treatment behaves differently in an acidic environment than in a neutral environment, the overall performance changes as well. The structure that contains the fillers with lower pH can accelerate the oxygen reaction significantly, achieving 2.5 V in OCV. As well, the potentiostat test exhibited higher electrochemical window with an operation voltage ranging from 1.2 V to 2 V under current densities of 1 mA cm-2, 2 mA cm-2, and 5 mA cm-2. Thus, the acceleration of the reaction kinetics results in a higher power output of the battery. Although further research is required, this hybrid carbon-based electrocatalyst is an excellent candidate for new high-power Zn-air batteries.
4:15 PM - ES04.23.03
Chemical Equilibrium and Electrochemical Deposition of Thermally Stable Electrolytes for Magnesium Batteries
Laura Merrill 1 , Hunter Ford 1 , Sunil Upadhyay 1 , Jennifer Schaefer 1
1 , University of Notre Dame, Notre Dame, Indiana, United States
Show AbstractThe commercialization of lithium-ion batteries allowed for the advancement of portable electronics and electric vehicles. These technologies have led to increased demand for lithium. Lithium-ion battery technologies are peaking performance wise; metal anodes are a viable option for increasing energy density of post lithium-ion batteries (PLIBs). Magnesium serves as a possible anode for PLIBs due to its widespread abundance and high theoretical volumetric capacity, nearly double that of lithium metal. The electrochemistry of magnesium has proven to be difficult and different from the lithium counterparts, as many analogous solutions result in the passivation of the magnesium active surface. High performing electrolytes are often based on tetrahydrofuran (THF), a volatile solvent. This study focuses on high boiling point solvents and gel matrices in order to increase the thermal stability of said electrolytes. We report on two different classes of electrolytes, 1. novel Hauser bases complexed with chloride salts in liquid solutions and 2. halide-free ionic polymer gel matrices. In both cases, the identity of the solvent is found to drastically impact chemical equilibrium, ion transport properties, and the electrodeposition/dissolution of magnesium metal. Speciation and electrochemical performance in glymes is found to be non-monotonic with chain length. Interfacial compatibility with non-ethereal solvents is also investigated.
4:30 PM - ES04.23.04
Lightweight Gas Diffusion Layer for Li-Air Battery via Layer-by-Layer Deposition
Mokwon Kim 1 , Jung Ock Park 1 , Joon-Hee Kim 1 , Dongmin Im 1
1 , Samsung Electronics Co., Ltd., Suwon-si Korea (the Republic of)
Show AbstractLithium-air (Li-air) battery has attracted considerable attention as next-generation lithium battery system because of its high specific energy (theoretically above 3500 Wh/kg). Despite the progresses that have been made to improve the capacity and lifetime of Li-air battery, achieving its potential specific energy still remains as a highly challenging goal because of the addition of components such as electrolyte, gas diffusion layer (GDL), current collector and sealing material. To increase the specific energy further, it is necessary to reduce the weight of cell components further. The GDL is an electrically conductive porous layer which is essential to supplying sufficient oxygen to the cathode during discharge. In this work, a novel material which can reduce the weight of GDL by replacing the widely used carbon paper GDL will be presented.
To prepare the lightweight GDL, we propose a novel structure in which carbon layer is uniformly coated on a polymeric nonwoven fabric. The porous structure of nonwoven fabric enables sufficient supply of oxygen to the cathode while the conductive carbon layer provides electrical conductivity in the GDL. The carbon nanotube (CNT)-based conductive layer is uniformly coated only on the surface of the fibers constituting the polymeric nonwoven fabric, so that the conductivity can be obtained with the minimum amount of coating layer. A layer-by-layer deposition based on non-ionic interaction between poly(4-styrene sulfonic acid) dispersing agent and poly(vinylalcohol) was used to fabricate uniform carbon coating layers. The resulting CNT coated polymeric nonwoven GDL showed the areal weight of 1 mg/cm2 and contributed to 20 % increase in the specific energy of Li-air battery. The details of GDL properties and cell performances will be discussed in the presentation.
4:45 PM - ES04.23.05
Layer-Structured Transition Metal Oxides as Cathodes for K-Ion Batteries
Haegyeom Kim 1 , Jae Chul Kim 1 , Dong-Hwa Seo 2 , Shou-Hang Bo 1 , Deok-Hwang Kwon 2 , Tan Shi 2 , Gerbrand Ceder 1 2
1 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 , University of California, Berkeley, Berkeley, California, United States
Show AbstractLi-ion batteries (LIBs) have succeeded in powering small portable electric devices and are currently expanding to large scale applications (i. e. electric vehicles and grid-level energy storage systems) but it is debatable whether the lithium reserve can meet the increasing demands on the emerging large scale applications. Under this consideration, K-ion batteries (KIBs) and Na-ion batteries (NIBs) are considered alternative energy storage systems due to the natural abundance of K and Na reserve. Especially, KIB technology is interesting because K has a lower standard redox potential than Na in non-aqueous carbonate-based electrolytes that are commonly used for NIBs.1-3 As a result KIBs can potentially have a higher cell voltage than NIBs if the cathode materials provide the same working voltage as their analogues in Na system. More importantly, graphite, which is a standard anode for LIBs, cannot reversibly intercalate Na ions, thus NIBs require expensive hard carbon anodes. On the other hand, graphite can store and release K ions reversibly, which in fact sparks research interest in KIBs.3,4
The discovery of novel positive electrodes is a critical step toward realizing KIBs. In this work, we develop new cathode materials with layered-structure (i. e. KxTMO2, TM = Co and Mn)5, 6 for KIBs and investigate K-storage properties and mechanism in them by in-situ diffraction and electrochemical characterization combined with theoretical first-principles calculations.
References
1. Eftekhari, A. et al. Potassium Secondary Batteries. ACS Appl. Mater. Sci., 9, 4404. (2016).
2. Marcus, Y. Thermodynamic functions of transfer of single ions from water to non-aqueous and mixed solvents: Part 3 - Standard potentials of selected electrodes. Pure and Applied Chemistry 57, 1129. (1985).
3. Komaba, S. et al. Potassium intercalation into graphite to realize high-voltage/high-power potassium-ion batteries and potassium-ion capacitors. Electrochem. Commun. 60, 172. (2015).
4. Jian, Z., et al. Carbon Electrodes for K-Ion Batteries. J. Am. Chem. Soc. 137, 11566. (2015).
5. Kim, H. et al. K-Ion Batteries Based on a P2-Type K0.6CoO2 Cathode. Adv. Energy Mater. 1700098. (2017)
6. Kim, H. et al. Investigation of potassium storage in layered P3-type K0.5MnO2 cathode. Submitted.