8:00 PM - EE5.2.03
Lithium Iodide as a Promising Electrolyte Additive for Lithium-Sulfur Batteries: Mechanisms of Performance Enhancement
Feixiang Wu 1,Jung Tae Lee 1,Naoki Nitta 1,Hyea Kim 1,Oleg Borodin 2,Gleb Yushin 1
1 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United States,2 Electrochemistry Branch Army Research Laboratory Adelphi United StatesShow Abstract
Achieving higher energy density, lower-cost, safer and more stable rechargeable batteries have been motivated by the rapidly rising market demand of advanced energy storage systems for use in transportation, electric grid and telecommunication. The use of Li-ion batteries is growing rapidly and playing an important role in our life due to their high specific energy and energy density. However, the current commercial cathode materials for Li ion cells are mainly Co-based and Ni-based intercalation-type cathode materials or lithium iron phosphate, which are relatively expensive and display theoretical capacities of ~300 mAhg-1. The low cost sulfur, working as cathode materials, is promising candidate with stimulant theoretical specific capacities of 1675 mAhg-1, which have been viewed by many authors as the next-generation lithium chemistry that offers improved safety and higher energy density [1-3]. Compared to S, The fully-lithiated Li2S can work with safer Li-free anodes, which makes it a more promising cathode material for rechargeable Li and Li-ion batteries [3-5].
Here, we report on the significant enhancement of electrochemical performance of Li2S/Li cells when lithium iodide (LiI) is used as a novel additive in organic electrolytes . LiI-containing cells show near-theoretical capacity utilization and excellent cycle stability. Our studies reveal that the LiI induces formation of Li ion permeable protective films on both the cathode and anode sides of the cell in-situ, which prevent the dissolution of polysulfides on cathode and reduction of polysulfides on anode, respectively, and keep the battery cost low and insure high coating uniformity. As a result, over 95.0% of the initial capacity is retained after 100 cycles, comparing to less than 77% for the cell without this additive. The addition of LiI into electrolyte also decreases the over-potential of 1st charge and voltage hysteresis. The cell rate performance was significantly enhanced with LiI additions. Since the reduction potential of the utilized electrolyte solvents is significantly smaller than the discharge potential for our cathodes, such finding is rather unexpected. Post-mortem analysis in combination with quantum chemistry studies provided insights on the mechanisms of the observed film formation and the resulting performance enhancements.
 P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J. M. Tarascon, Nature materials 2012, 11, 19.
 X. Ji, K. T. Lee, L. F. Nazar, Nature materials 2009, 8, 500.
 F. Wu, H. Kim, A. Magasinski, J. T. Lee, H. T. Lin, G. Yushin, Advanced Energy Materials 2014, 4, 1400196.
 F. Wu, J. T. Lee, A. Magasinski, H. Kim, G. Yushin, Particle & Particle Systems Characterization 2014, 31, 639.
 F. Wu, A. Magasinski, G. Yushin, Journal of Materials Chemistry A 2014, 2, 6064.
 F. Wu, J. T. Lee, N. Nitta, H. Kim, O. Borodin, G. Yushin, Advanced materials 2015, 27, 101.
8:00 PM - EE5.2.08
O and N Ion Battery with Transition Metal as Anode
Satyesh Yadav 1,Blas Uberuaga 1
1 Los Alamos National Laboratory Los Alamos United States,Show Abstract
Several transition metals are known to dissolve high percentage of oxygen. We investigate the possibility of using transition metals as anode materials with N, O, or F as conducting ions. Two important factors that are required for metal to act as good candidate for metal-air batteries are: i) ease of N, O, or F intercalation and ii) small volumetric changes as the concentration of dissolved oxygen is varied. In this study using first-principles density functional theory (DFT) and hybrid-DFT, we study thermodynamic stability of N, O, or F interstials and corresponding volumetric change in range of metals.
We study transition metals from period 4, 5, and 6. We compare N, O, or F interstial formation energy with formation energy per N, O, or F of corresponding most stable oxide, nitride, and fluoride. As an outlier to rest of metals considered, we find that it is thermodynamically favorable to form O and N interstial compared to its most stable oxide and nitride in Ti, Zr, Hf, and V, respectively. This provides a thermodynamic driving force for O or N to diffuse into Ti, Zr, Hf, and V metals rather than forming oxide layer. There is a very small volumetric expansion due to O and N interstitial in Ti, Zr and Hf but large for V. These results suggest that Ti, Zr, and Hf can be suitable candidate for O or N ion battery.
8:00 PM - EE5.2.09
Two-Dimensional Gallium Sulfide Nanosheets Produced by Liquid-Phase Exfoliation of Commercial Layered Powders: High Capacity Anode for Advanced Li-Ion Battery
Chuanfang (John) Zhang 1,Sang Hoon Park 1,Oskar Ronan 1,Andrew Harvey 1,Sean O'Brien 1,Jonathan Coleman 1,Valeria Nicolosi 1
1 Trinity College Dublin Dublin Ireland,Show Abstract
The ever-increasing demand of advanced lithium-ion batteries (LiBs) require the electrode materials possessing exceptional electrochemical performances, cost-effective properties and the capability of scaling up.1 Liquid-phase exfoliation of commercial bulk powders which produces two-dimensional (2D) defect-free nanosheets, is not only an economic route but also having the potential of scalable production.2–5 As a family member of III-VI layered semiconductors, gallium sulfide (GaS) has many exciting properties, among which is the potential in LiBs. Here we exfoliated the commercial GaS powders to obtain the 2D GaS nanosheets,6 followed by hybridizing with single-wall carbon nanotubes (SWCNT) to form a free-standing composite paper electrode. As the LiBs anode, the flexible composite paper shows a high gravimetric capacity of 800 mAh g-1 at 100 mA g-1 and still retains 270 mAh g-1 at 1000 mA g-1. These values are much higher than the reported ones.7 The capacity of GaS component in the composite paper is over 1000 mAh g-1 at 100 mA g-1, which greatly exceeds the values of GaS electrode without SWCNT. This result clearly indicates the synergistic effect between the high-capacity GaS nanosheets and the conductive SWCNT. Furthermore, it was found that through using the electrolyte additive, the formation of solid-electrolyte interphase (SEI) could be suppressed, resulted in much improved cycling performance and rate capability in the flexible composite paper. Finally, effect of mass loading on the capacity of composite paper electrode, both gravimetrically and volumetrically, has been studied. These results imply that the great potential of GaS/CNT flexible paper electrode as the anode for advanced LiBs.
1 P. G. Bruce, B. Scrosati and J.-M. Tarascon, Angew. Chem. Int. Ed. Engl., 2008, 47, 2930–46.
2 K. R. Paton, E. Varrla, C. Backes, et al., Nat. Mater., 2014, 13, 624–30.
3 Y. Hernandez, V. Nicolosi, M. Lotya, et al., Nat. Nanotechnol., 2008, 3, 563–8.
4 J. N. Coleman, Acc. Chem. Res., 2013, 46, 14–22.
5 M. Lotya, Y. Hernandez, P. J. King, et al., J. Am. Chem. Soc., 2009, 131, 3611–20.
6 A. Harvey, C. Backes, Z. Gholamvand, et al., Chem. Mater., 2015, 27, 3483-3493.
7 X. Meng, K. He, D. Su, et al., Adv. Funct. Mater., 2014, 24, 5435–5442.
8:00 PM - EE5.2.11
One-to-One Comparison of Silicon Nanolayer-Embedded Graphite Anodes with Commercial Benchmarking Materials as Feasible Candidates for High Energy Lithium-Ion Battery
Namhyeong Kim 1,Jaephil Cho 1
1 UNIST (Ulsan National Institute of Science and Technology) Ulsan Korea (the Republic of),Show Abstract
To date, in practical lithium ion batteries (LIBs), the commercial application of pure Si as anode material is tough challenge due to its intrinsic drawbacks including tremendous volume variation during the repeated lithium alloying/dealloying reaction. In this respect, the SiOx , whose the reversible capacity is about 1600mAh g-1 with 74% of initial coulombic efficiency, has been extensively researched as strong alternative because it shows the enhanced cycle stability and low volume change during electrochemical reaction compared with pure Si. Recently, to increase capacity of the anode electrode, the graphite composite with SiOx (3wt %) has been used in full cells. However, even though the SiOx can provide a high capacity as high as 1600mAh g-1, due to its low initial efficiency, the increment of the SiOx proportion is a crucial issue for the Li-finite full-cell system. In our previous report, through the industrial-relevant designed CVD which is possible to make a mass production, we successfully synthesized Si nanolayer-embedded graphite/carbon hybrids (SGC) exhibiting a high reversible capacity (523mAh g-1) with excellent coulombic efficiency (92%) at a 1st cycle and remarkable capacity retention (96%) after 100 cycles.
Herein, we have intensively focused on the one-to-one comparison between SGC and state-of-the-art benchmarking samples including the SiOx and Si/graphite composite which have been supplied as commercial anode in major battery companies. For a direct comparison, the specific capacity of all samples were fixed at 420mAh g-1 by graphite blending as the forthcoming LIB anode and all electrochemical tests were conducted at real industrial electrode condition such as high electrode density (> 1.6g cc-1), high areal capacity (> 3.0 mAh cm2) and limited SBR/CMC binder composition (< 4wt %) . The electrochemical evaluations, also, were reported in the full-cell as well as in the half-cell configurations. As a result, the performance of the SGC blending system achieved outstanding cycle retention (< 98%) in the half-cell after 50th cycles and also allowed the highest coulombic efficiency (
8:00 PM - EE5.2.12
Nanostructured Iron and Nickel Electrodes for Rechargeable Alkaline Batteries
Danni Lei 1,Dong-Chan Lee 1,Alexandre Magasinski 1,Enbo Zhao 1,Daniel Steingart 2,Gleb Yushin 1
1 Georgia Institute of Technology Atlanta United States,2 Princeton University Princeton United StatesShow Abstract
Flammability and high cost of lithium ion batteries limit their market adoption rate in price-sensitive applications. Therefore, rechargeable aqueous batteries have attracted renewed attention due to their environmental friendliness, the intrinsic flame resistance of aqueous electrolytes, most importantly, greatly reduced capital and operating cost.1-3 Recently, we successfully utilized a solution-based synthesis of strongly coupled nanoFe/multiwalled carbon nanotube (MWCNT) and nanoNiO/MWCNT nanocomposite materials for use as anodes and cathodes in rechargeable alkaline Ni-Fe batteries. The produced aqueous batteries demonstrate very high discharge capacities, which exceed that of commercial Ni-Fe cells by nearly an order of magnitude at comparable current densities. The use of highly conductive MWCNT network allows for high capacity utilization due to rapid and efficient electron transport to active metal nanoparticles in oxidized (such as Fe(OH)2 or Fe3O4) states. The flexible nature of MWCNTs accommodates significant volume changes taking place during phase transformation accompanying reduction-oxidation reactions in metal electrodes. The electrolyte molarity and composition have a significant impact on the capacity utilization and cycling stability. Based on our post-mortem analyses, we came to the following conclusions: (i) at high alkaline electrolyte concentration and thus high pH values the Fe dissolution and re-precipitation takes place, which reduces the rate performance and capacity utilization of the nanostructured Fe anodes; (ii) at lower pH values Fe dissolution could be mitigated, but hydrogen evolution (HE) takes place, which becomes particularly significant if high surface area nanostructured Fe anodes are used; (iii) the addition of LiOH to KOH electrolyte enhances the Fe dissolution, but reduces the anode polarization and capacity utilization; these findings correlate well with the formation of porous oxidized Fe in LiOH-comprising electrolytes.
 S. Liu, G. L. Pan, N. F. Yan, X. P. Gao, Energy Environ. Sci., 2010, 3, 1732.
 C. Xu, B. Li, H. Du, F. Kang, Angew. Chem. Int. Ed. 2012, 51, 933.
 Z. Liu, S. W. Tay, X. Li, Chem. Commun., 2011, 47, 12473.
This work was partially supported by the Advanced Research Projects Agency- Energy (grant DE-AR0000400).
8:00 PM - EE5.2.13
Rechargeable Ni-Na Aqueous Battery with Hierarchical Nanostructured Ni(OH)2 Electrodes
Seungyoung Park 1,Ziyauddin Khan 1,Youngsik Kim 1,Hyunhyub Ko 1
1 Ulsan National Institute of Science and Technology(UNIST) Ulsan Korea (the Republic of),Show Abstract
The development of rechargeable battery systems have recently accelerated the various energy storage applications from portable electronic devices to hybrid electrical vehicles. Nickel-metal hydride (Ni-MH) battery has a high capacity (2-3 times than that of an equivalent size NiCd battery) at an energy density similar to that of a lithium-ion battery. In addition, its aqueous electrolyte system is safer than the Li-ion battery, where the aprotic electrolyte system causes the flammable problem especially in the hybrid electric vehicles. However, its cell voltage is low (1.32 V) because of the aqueous electrolyte system. It is important to meet both the high cell voltage and high cell capacity in the aqueous electrolyte system for practical applications.
Herein, we propose a rechargeable Ni-Na aqueous battery system with Na electrode and wrinkled Ni-based nanostructures as anode and cathode materials, respectively. Na based rechargeable battery system has recently attracted great attentions as the next-generation battery system because of the similar mechanism with the Li-based rechargeable battery system and their abundant reserves. In addition, as the anode material, 3D-wrinkled Ni-based nanostructures are directly constructed on carbon microfibers offering the binder-free electrodes. The 3D Ni-based wrinkled nanostructure shows an enhanced performance with high surface area and high capacity (280mAh/g at rate of 1mA). Importantly, the Ni-Na battery offers the high average discharge voltage (3.1V) and shows a high capacity resulting in the high energy density (837Wh/kg).
8:00 PM - EE5.2.14
Metal Oxychloride/Metal Electrode Systems for Chloride-Ion Batteries
Xiangyu Zhao 1,Meng Yang 1,Xiaodong Shen 1
1 Nanjing Tech University Nanjing China,Show Abstract
Rechargeable batteries are receiving particular attention in diverse areas of portable electronic devices, electric vehicles (EV) and other energy storage systems. We previously reported the proof-of-principle of a new concept of rechargeable batteries based on chloride shuttle, i.e., chloride ion batteries. The concept has the advantage of a broad variety of potential electrochemical couples with high theoretical energy density up to values of 2500 Wh/L, which is higher than the theoretical energy density of the current lithium ion battery. Moreover, chloride ion batteries can be built from abundant material resources and have environmentally friendly features. These attributes could make the chloride ion battery a potential alternative in the field of rechargeable batteries.
A key challenge is to suppress the dissolution of cathode materials mainly composed of transition metal chlorides, which are Lewis acid and can react with a Lewis base containing chloride ion in the electrolyte, resulting in the formation of soluble complex ions. One approach is to use metal oxychlorides as cathode materials. For the FeOCl cathode (FeOCl/Li), a reversible discharge capacity of 184 mAh g-1 was measured, which is based on the phase transformation between FeOCl and FeO. Two stages of this phase transformation are observed for the FeOCl cathode. These results suggest that metal oxychlorides are promising cathode materials for chloride ion batteries.
An advantage of chloride ion batteries is the use abundant materials such as Mg, La, Ca and Na as anode materials. We found that Mg is promising as anode material based on our new results. For instance, the BiOCl cathode (BiOCl/Mg) showed a discharge capacity of 70 mAh g-1, i.e., 68% of theoretical capacity at the second cycle. The electrochemical performance of metal oxychloride/Mg systems was investigated including single electron or multi-electron cathode. Moreover, a new approach was tested using multi-electron vanadium oxychloride (VOCl) cathode and Mg/MgCl2 composite anode.
8:00 PM - EE5.2.15
A Computational Study of Lithium Interaction with Tetracyanoethylene (TCNE) and Tetracyaniquinodimethane (TCNQ) Molecules for Organic Batteries
Sergei Manzhos 1,Yingqian Chen 1
1 National Univ of Singapore Singapore Singapore,Show Abstract
Organic batteries are an extremely promising electrochemical storage technology as they promise high rate (high power) and sustainable batteries with environment-friendly inputs. Organic batteries are also promising for the development of post-lithoum batteries such as sodium ion batteries. While there is a growing body of experimental works studying various potential organic electrode materials, theoretical/computational studies are rare; they are however essential to guide rational as opposed to ad hoc design of better organic electrode materials.
Here, we present a study of the mechanism of interaction of Li with molecules which are promising for use in organic electrodes: tetracyanoethylene (TCNE) and tetracyaniquinodimethane (TCNQ). TCNE and TCNQ have previosuly been proposed as promising candidate materials for organic battery electrodes, including lithium ion as well as sodium ion batteries. Their high theoretical capacities are in particular due to the possibility to store more than one alkali atom per molecule. We present a density functional theory study of lithium attachment to TCNE and TCNQ. Trends in the Li binding strengths (which determines the electrode voltage) are presented between TCNE and TCNQ and a function of the number of attached Li atoms. We show that multiple Li attachment induces non-trivial changes in the electronic structure which involves electron donation to higher (than LUMO) unoccupied molecular orbitals as well as Li-centered orbitals. Strain effects induced by Li attachment lead to significant changes in the electronic structure including changes in orbital ordering. A new cyclic molecular structure stabilized by Li attachment to TCNE is identified. We conclude that design of organic electrode materials should consider the energies of higher (than LUMO) orbitals as well as effects of structural changes on the electronic structure.
8:00 PM - EE5.2.16
Ab Initio Molecular Dynamics Characterization of La-Based Perovskite-Type Oxides for Metal-Air Cell Cathodes
Aysegul Afal Genis 1,Mehmet Kadri Aydinol 1
1 Department of Metallurgical and Materials Engineering Middle East Technical University Ankara Turkey,Show Abstract
Oxygen reduction reaction (ORR) catalytic activities have been of great scientific importance for extensive studies in energy storage technologies, specifically in metal-air batteries. Metal-air batteries are promising for future applications of especially electrical vehicles due to the utilization of oxygen from the air as one of the battery’s main components. Kinetic performance of the electrochemical reaction taking place in these batteries mainly depends on the reduction of oxygen at the cathode. Different groups of catalysts have been considered in order to facilitate ORR at the air electrodes including precious metal catalysts, metal oxides and carbons. Contrary to the ORR on metals and metal alloys in acidic environments, little is known about the influence of intrinsic properties of complex oxides on their activity toward the ORR in alkaline media. To develop novel and highly active cathode materials, a deeper understanding of the correlation between the cathode material properties and ORR activity is necessary. The crucial role of electronic structure in determining the electrochemical activity has been well recognized in the field of catalysis. First-principles computational studies, in particular density functional theory (DFT) studies, have made important contributions to such efforts, identifying fundamental correlations between catalytic activity and electronic structure for different types of catalyst materials. Therefore, ab initio methods become a useful tool to characterize catalytic properties by examining electronic structures, reaction energetics and activation energies. In this study, the effect of surface crystallography on oxygen molecule dissociation and adsorption properties on different types of transition metal perovskites of the type ABO3 (A=La, B= Mn, Cr, Fe, O=oxygen) are presented. To analyze the oxygen–perovskite interaction, ab initio molecular dynamics method is used to simulate the behavior of O2 at the surface. This method is expected to show whether the transition metal elements displayed an effect of catalyzer in terms of dissociation of the O2 molecule into O atoms at the surface. A systematical study within adsorption characteristics of oxygen on La-based perovskite surfaces was performed. In addition, via ab initio molecular dynamics simulations, what kind of an effect would different planes make on oxygen behavior at the surface was studied. Ab initio molecular dynamics simulations were executed on clean low- index (001) and (111) surfaces of perovskites. Simulations were done by ab initio pseudopotential method within the generalized gradient approximation (GGA) to density functional theory (DFT).
8:00 PM - EE5.2.17
Graphene Oxide Enhanced Polyacrylonitrile Nanofiber Membrane Used as Seprator for Achieveing High-Performance Lithium-Sulfur Batteries
Jiadeng Zhu 1,Xiangwu Zhang 1
1 North Carolina State Univ Raleigh United States,Show Abstract
Sulfur has been considered as a promising cathode candidate for next generation batteries due to its high theoretical capacity and energy density. However, the severe self-discharge behavior strongly limits the practical applications of lithium-sulfur (Li-S) batteries. Here, we report a sustainable and highly porous polyacrylonitrile/graphene oxide (PAN/GO) nanofiber membrane which can be performed as a novel separator for lithium-sulfur batteries to achieve high stable capacity and excellent anti-self-discharge feature. A superior low retention loss of 5% can be obtained even after a resting time of 24 h not only due to the relatively high energy binding between –C≡N and Li2S/Li-S radicals but to the electrostatic interactions between GO and negatively charged species (Sn2-). It is, therefore, demonstrated that this GO incorporated PAN as-spun nanofiber with highly porous structure and excellent electrolyte wettability is a promising separator candidate for high-performance Li-S batteries.
8:00 PM - EE5.2.18
Influence of Fluorine Incorporation of Directly Disulfonated Copolymer Membranes on the Vanadium Redox Flow Battery (VRFB) Performance
Kenan Kara 1,Levent Semiz 1,Tunc Eren Akay 1,Erkan Aydin 1,Nurdan Demirci Sankir 1,Mehmet Sankir 1
1 Materials Science and Nanotechnology Engineering TOBB University of Economics and Technology Ankara Turkey,Show Abstract
Vanadium redox flow batteries (VRFBs) have been demonstrated as energy efficient conversion devices with long service life. Moreover, VRFBs have been assumed as highly cost effective when inexpensive membranes were utilized. The state-of-art membrane Nafion™, perfluorinated copolymer, has been the most commonly used membrane although it suffers from its high cost, lower proton conductivity and higher vanadium permeability. Therefore, much efforts has been focused on replacing Nafion™. Also there is a great interest to compare and contrast VRBF performances of both fluorinated and non-fluorinated based hydrocarbon membranes. This study focuses on the effect of fluorine moeity of directly disulfonated (35 molar %) poly(arylene ether benzonitrile) copolymer (PAEB) membranes on the VRFB performance. The fluorine incorporation from 25 to 100 molar percents has been systematically varied by using hexafluoro-isopropylidene diphenol (6F) monomer during copolymerization. It was demonstrated that efficiencies of VRBF prepared from both fluorinated and nonfluorinated copolymer membranes were better than that of N212. The columbic efficiencies of copolymer membranes not bearing any fluorine content (PAEB35) and Nafion™ were about 98.7 and 87.6 percents at the current density of 20 A cm-2, respectively. Once a 100 molar percent fluorination (6F100PAEB35) was achieved, the columbic efficiency was about 99.5, which was one of the best efficiencies reported in the literature. This trend was also observed at higher current densities. The superiority in the columbic efficiency was due to the lower vanadium permeabilities of the 6F100PAEB35 copolymer membranes (1.0 x 10-13 m2 s-1). Among the series, 6F100PAEB35 had 4-fold lower vanadium permeability than PAEB35. On the other hand the vanadium permeabilities of 6F100PAEB35 were about 8 times lower than that of N212 (1.3 x 10-12 m2 s-1). The proton conductivity of the PAEB 35 is 77 mS cm-1. As the fluorine content increased from 0 to 100 molar percent the ion exchange capacity (IEC) decreased from 1.86 to 1.31 mequiv g-1. Since, the proton conductivity and water uptake values which were function of IEC followed the same trend and decreased from 77 to 56 mS cm-1 and from 39 to 22 wt% with increasing fluorine content, respectively. Therefore voltage efficiencies of fluorine bearing copolymer membranes were slightly lower than their non-fluorinated analogous in the series. For example, the voltage efficiencies of PAEB 35 and 6F100PAEB35 were about 92.8 to 91.8 % at 80 mA cm-2, respectively. Moreover, overall efficiencies of both fluorinated (91.2 %) and nofluorinated copolymer membranes (91.6 %) were far better than N212 (80.5%). The selectivity (e.g., proton conductivity/permeability) of fluorinated series was about 3 and 20 times higher than non-fluorinated copolymer membranes and N212, respectively. These highly selective copolymer membranes have been utilized as promising candidates for VRFBs.
8:00 PM - EE5.2.19
Ternary Metal Fluorides as New High-Energy Cathodes for Rechargeable Lithium Batteries
Feng Wang 1,Sung-Wook Kim 1, Dong-Hwa Seo 2,Kisuk Kang 2,Liping Wang 1,Dong Su 1,John Vajo 3,John Wang 3,Jason Graetz 3
1 Brookhaven National Laboratory Upton United States,2 Seoul National University Seoul Korea (the Republic of)3 HRL Laboratories Malibu United StatesShow Abstract
Transition metal fluorides are promising high-capacity battery cathode for large-scale applications (i.e. electric vehicles), but issues related to low voltage, large hysteresis and limited cycling reversibility remain a major hurdle to their commercial application. Here we report on the synthesis, structural and electrochemical properties of new nanostructured ternary metal fluorides, which may overcome some of these issues. By substituting Cu into the Fe lattice, forming the solid solution CuyFe1-yF2, reversible Cu and Fe redox reactions were achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new pathway for tailoring electrochemical properties of conversion electrodes . The Li storage/release mechanisms and limits to cycling stability of CuyFe1-yF2 were also investigated by combining electrochemical measurement with comprehensive structural and chemical analysis using in-situ X-ray absorption spectroscopy, X-ray diffraction, and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS). Detailed lithium reaction mechanisms, Cu-loss related issues along with possible remedy solutions in the CuyFe1-yF2 system, will be discussed. The work was supported as part of the NorthEastern Center for Chemical Energy Storage, an EFRC Center funded by the U.S. DOE-BES, under Award Number DESC0001294, and by DOE-EERE under the Advanced Battery Materials Research program, under Contract No. DE-SC0012704.  Wang et al., “Ternary Metal Fluorides as High-Energy Cathodes with Low Cycling Hysteresis”, Nat. Commun. 6:6668 (2015).
8:00 PM - EE5.2.20
Porous 2D Transition Metal Carbides (MXenes) for High-Performance Lithium-Ion Storage
Chang Ren 1,Meng-Qiang Zhao 1,Taron Makaryan 1,Joseph Halim 1,Muhammad Boota 1,Sankalp Kota 1,Babak Anasori 1,Yury Gogotsi 1
1 Drexel Univ Philadelphia United States,Show Abstract
Introduction of well-designed micro-, meso- or macro-porous structures into functional building blocks, generally leads to significantly improved or unexpected physiochemical properties and performance. MXenes are a family of 2D transition metal carbides, which have shown great promise as electrodes in lithium-ion batteries and supercapacitors. However, the accessibility of electrolyte ions into MXenes is limited due to the compact stacking of the 2D flakes, hindering the full utilization of their energy storage performance. Herein, we successfully introduce porous structure into MXene flakes and demonstrate the significant improvement of their Li-ion storage capability.
The porous structure was introduced into MXenes by an easy and controllable chemical etching method. Typically, Ti3C2 colloidal solution was mixed with an aqueous solution of transition metal salts (e.g. CuSO4, CoSO4 or FeSO4) at room temperature while stirring for 30 min. The suspension was washed by 5 wt.% HF aqueous solution and vacuum filtered. This process resulted in a freestanding and flexible p-Ti3C2 film with large quantity of pores on Ti3C2 flakes, which enhanced its specific surface area. The electrochemical performance of p-Ti3C2 was evaluated by using p-Ti3C2/CNT composite film as anode material in Li-ion batteries. At 0.5 C, a capacity of ≈750 mAh g-1 was achieved, much larger compared to that of the non-porous Ti3C2/CNT film (≈220 mAhg-1), along with excellent cycling stability. The p-Ti3C2/CNT electrode also showed impressive rate performance. A high capacity of ≈1250 mAh g-1 was achieved at 0.1 C after a pre-cycling process, and ≈330 mAh g-1 was retained at 10 C. This chemical etching method, which is applicable to other kinds of MXenes (V2C and Nb2C), provides a simple yet effective method to improve the physiochemical properties of MXenes, and possibly other kinds of 2D materials.
Gleb Yushin, Georgia Institute of Technology
Bruce Dunn, University of California, Los Angeles
Arumugam Manthiram, University of Texas at Austin
Linda Nazar, University of Waterloo
SABIC Americas, Inc
Toyota Research Institute of North America
EE5.3/EE6.4: Joint Session: High Capacity Anodes for Rechargeable Li and Li-Ion Batteries
Wednesday AM, March 30, 2016
PCC North, 100 Level, Room 124 B
8:00 AM - *EE5.3.01/EE6.4.01
Electrodeposition of Metals in Nanostructured Electrolytes: Transport Phenomena and Stability
Lynden Archer 1
1 School of Chemical amp; Biomolecular Engineering Cornell University Ithaca United States,Show Abstract
Electrodeposition is used in various manufacturing processes for creating metal, colloid, and polymer coatings on conductive electrode substrates. The process also plays an important role in electrochemical storage technologies based on 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) in an electrolyte and stable redox reactions and transport at the electrolyte/electrode interface at which the deposition occurs. This talk considers the stability of electrodeposition of metals on planar electrodes with an emphasis on its role in enabling next-generation secondary batteries based on lithium and sodium metal anodes. Such batteries promise substantial improvements in electrochemical energy storage over todays’s state-of-the art lithium ion technology and are under active investigation worldwide.
Development of a practical rechargeable lithium metal battery (LMB) remains a challenge due to uneven lithium electrodeposition and formation of ramified denderitic electrodeposits during repeated cycles of charge and discharge. Known consequences of unstable electrodeposition in LMBs include accumulation of electrically disconnected regions of the anode or “dead lithium”, thermal runaway of the cell, and internal short circuits, which limit cell lifetime and may pose serious hazards if a flammable, liquid electrolyte is used in a LMB. Lithium-ion batteries (LIBs) are designed to eliminate the most serious of these problems by hosting the lithium in a graphitic carbon substrate, but this configuration is not entirely immune from uneven lithium plating and dendrite formation. Specifically, the small potential difference separating lithium intercalation into versus lithium plating onto graphite, means that a too quickly charged or overcharged LIB may fail by similar mechanisms as a LMB.
Using a continuum transport analysis for electrodeposition in a structured electrolyte in which a fraction of the anions are fixed in space, the talk will show that electrodeposition at the lithium anode can be stabilized through rational design of the electrolyte and salt. Building upon these ideas, the talk will explore structure and transport in novel nanoporous hybrid electrolyte configurations designed to stabilize metal anodes against dendritic electrodeposition and premature failure. Finally, the talk will explore an application of these electrolyte designs for LMBs to evaluate stability conditions deduced from theory.
8:30 AM - EE5.3.02/EE6.4.02
Practical Investigation of Silicon Oxide Anode Material for Lithium-Ion Batteries
Yeonguk Son 1,Soojin Sim 1,Hyunsoo Ma 1,Yoonkook Son 1,Suhyeon Park 1,Jaephil Cho 1
1 UNIST Ulsan Korea (the Republic of),Show Abstract
Successful strategies of silicon (Si)-based anode materials for lithium ion batteries (LIBs) have numerously reported during past decade, such as nano-designed Si structure, stronger new binder system, Si composite with other materials, and so on. However most of those strategies provided only specific energy or power density with low volumetric energy density or area capacity. The superior stability of specific energy or power density couldn’t represent the higher electrochemical performance in practical application for LIBs. To investigate the practical use of anode materials, initial area capacity of anode should be higher than 3.7 mAh/cm2 which is commercial level of graphite. It appears in high loading level that the more critical problems due to volume expansion which doesn’t appear in low loading level. Moreover, high loading level causes fast degrading of lithium metal in half-cell test. Thus electrochemical test of high loaded electrode should be conducted in a full-cell test. Therefore, here we conducted full-cell electrochemical test of Si oxide-based anode with high loading (also using only 3wt% of CMC/SBR binder) while physical mixing of LiCoO2 and Ni-rich cathode as cathode material, also known as commercialized cathode material for LIBs, and investigated its detailed fading mechanisms out to 1000 cycles.
Our investigation scope of the fading mechanism is from electrode level to atomic level. To verify the effect of electrode volume change, the thickness of electrode and solid-electrolyte-interphase (SEI) layer was measured after cycle test and chemical compositions of SEI layer were analyzed by X-ray photoelectron spectroscopy (XPS). To observe the atomic structure of electrode materials, high resolution-transmission electron microscopy (HR-TEM) were operated after long-term cycling. On the evidence of ex-situ analysis and electrochemical result, we created the algorithm for the possible fading mechanism of Si-based anode. We also separated the reasons of fast and gradual degrading respectively and suggested the behaviors of idealized Si-based anode. We believe that our findings provide a foundation to clearly verify fading mechanism of Si-based anode for LIBs and envision the considerations of future Si-based anode for practical use.
8:45 AM - EE5.3.03/EE6.4.03
Effect of Composition and Structure on Electrochemical Properties of Ternary Type I Silicon Clathrates for Lithium-Ion Battery Anodes
Candace Chan 1,Ran Zhao 1
1 Arizona State Univ Tempe United States,Show Abstract
Silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on M8YxSi46-x (M = Ba, Sr; Y = Al, Cu, Ni) as the anode material for lithium-ion batteries. For the Ba-Al-Si system, post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li (~1 Li/Si) into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from large volume changes. The electrochemical reactions are proposed to occur as single phase reactions at approximately 0.2 and 0.4 V vs. Li/Li+ during lithiation and delithiation, respectively, distinct from diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g-1 at a 5 mA g-1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to ~1.18 Li/Si. These results show that silicon clathrates could be promising durable anodes for lithium-ion batteries. Changing the composition of the clathrate, namely replacing the Ba guest atom and Al framework substitution with other metals, was found to have a strong effect on the number of Li reversibly inserted into the structure and the shape of the voltage profile.
9:00 AM - *EE5.3.04/EE6.4.04
Current Status of Si-Based Anode Materials for High Capacity Li-Ion Batteries
Jaephil Cho 1
1 UNIST Ulsan Korea (the Republic of),Show Abstract
Si has been considered as a promising alternative anode for next-generation Li-ion batteries (LIBs) because of its high theoretical energy density, relatively low working potential, and abundance in nature. However, Si anodes exhibit a rapid capacity decay and increase in the internal resistance, which are caused by the large volume changes upon Li insertion and extraction. This unfortunately obstructs their practical applications. Therefore, managing the total volume change remains a critical challenge for effectively alleviating the mechanical fractures and instability of solid-electrolyte-interphase products. In this regard, in spite of many new ideas being published, all of them are still from practical implantation in the Li-ion batteries. Accordingly, it is inevitable to composite with the graphite to minimize the volume change and to balance with the cathode material. In this talk, I am going to present new advanced results of the Si and graphite composites with reversible capacity of < 600 mAh/g, which can be immediately implanted in the full cell.
9:30 AM - EE5.3.05/EE6.4.05
Limits of Energy Density in Silicon Anode Based Lithium-Ion Batteries
Ranjan Dash 1,Sreekanth Pannala 2
1 SABIC Exton United States,2 SABIC Sugar Land United StatesShow Abstract
Silicon is considered as a potential next-generation anode material for lithium ion battery (LIB). Experimental reports of up to 40% increase in energy density of silicon anode based LIBs have been reported in literature. However, such increase in energy density is achieved when silicon anode based LIB is allowed to swell more than graphite based LIB and beyond permissible limits. For practical applications such as in automotive or mobile devices, one cannot have any volume expansion. We determine the theoretical bounds of silicon composition in a silicon – carbon composite (SCC) based anode to maximize the volumetric energy density of LIB by assuming no increase in the external dimensions of the anode during charging. The porosity of SCC anode is adjusted to accommodate the volume expansion during lithiation. The determined threshold value of silicon was then used to calculate the volumetric energy densities of SCC anode based LIBs and improvement over graphite anode based LIBs for three types of cathodes - lithium cobalt oxide (LCO), lithium manganese cobalt oxide (NMC) and lithium nickel cobalt aluminum oxide (NCA), and at a constant cathode thickness of 70 μm. The maximum improvement in the volumetric capacity of SCC anode based LIB over graphite anode based LIB for LCO, NMC and NCA cathodes was determined to be ~20%, ~22%, and ~24%, respectively. Theoretical maximum in the volumetric capacity and energy density is obtained when it is assumed that there is zero porosity in the lithiated anode and that the displaced electrolyte does not need additional volume. The level of practically achievable improvements in capacity and energy density of silicon anode based LIBs is expected to be between 5-15% for lithiated anode porosities of 10-30% to ensure the battery has similar life and power characteristics of conventional LIB.
EE5.4/EE6.5: Joint Session: Electrochemical Interfaces in New Battery Chemistry
Wednesday AM, March 30, 2016
PCC North, 100 Level, Room 124 B
10:00 AM - *EE5.4.01/EE6.5.01
Realization of Metal Fluoride Conversion Nanocomposite Electrodes for Batteries
Glenn Amatucci 1,Nathalie Pereira 1,Fadwa Badway 1
1 Rutgers University North Brunswick United States,Show Abstract
Metal fluoride conversion electrodes have been of fundamental interest as high energy density electrodes for lithium batteries for over 40 years, however, the theoretical electrochemical activity of such materials remained elusive as a result of their high bandgap and poor ionic and electronic charge transport characteristics. Well over a decade ago, electronically and mixed conducting matrices to form metal fluoride nanocomposites resulted in the revelation of the theoretical voltages, high energy densities, and minimal reversibility of some of the most promising fluorides and oxyfluorides which operate over 2V. Since this time many in our community have investigated these materials and advanced the state of the science significantly. This paper will discuss a sampling of the scientific, technological, and practical questions that still stand today as supported by examples of research from the community and our laboratories.
10:30 AM - *EE5.4.02/EE6.5.02
Solid State Batteries: Promise and Challenges
Nancy Dudney 1
1 Oak Ridge National Laboratory Oak Ridge United States,Show Abstract
Achieving solid state batteries that operate at room temperature is an elusive, but compelling goal, one that researchers have been working on decades. Solid state batteries hold the promise of much safer and robust energy storage, with potentially higher energy density as well. But the challenges for a thin, stable solid electrolyte with adequate transport and mechanical properties, plus a practical route for large scale manufacturing is daunting. Perhaps more worrisome is the challenge of a stable interface with electrodes being single phase or solid composites. How can the electrodes cycle many times while still maintaining good physical contact and low resistance to ion transport with the solid electrolyte? Should we perhaps compromise with an “almost all” solid state battery? What energy densities can we reasonably expect? Can advanced manufacturing methods provide solutions?
This presentation highlights recent research at ORNL and with our collaborators, as well as reports from other groups, that clearly point out the challenges facing solid state battery development, where we lack fundamental understanding of materials and interfaces, and pragmatic approaches that might move us toward a near term success.
Acknowledgements: The presenter thanks co-editors, William E. West and Jagjit Nanda, and the contributing authors of the Handbook of Solid State Batteries, 2015, for their insights. Research conducted at ORNL was supported by the U.S. Department of Energy through the Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (for inorganic solid electrolytes) and through the Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Advanced Battery Materials Research program (for polymer and composite electrolytes).
11:00 AM - *EE5.4.03/EE6.5.03
Coulombic Inefficiency and the Structure Directing Role of Interfacial Films on Magnesium and Lithium
Kevin Zavadil 1
1 Sandia National Labs Albuquerque United States,Show Abstract
Achieving significant gains in energy density and specific energy beyond lithium ion battery technology will require the use of alkali (lithium) and alkaline earth (magnesium) metals as anodes. Power requirements over a practical temperature range necessitate the use of these reactive metals in direct contact with a liquid electrolyte resulting in parasitic reactions yielding solid electrolyte interphases that control the accommodation and removal of metal during energy release (discharge) and energy storage (charging cycles). Where Li dendrite formation is the most readily recognized form of loss of dimensional control leading to safety concerns, structural changes that lead to Coulombic efficiency loss are far more common for Li anodes in oxygen and sulfur cells and for Mg anodes coupled with insertion and sulfur cathodes. We explore the origins of loss of dimensional control due to film formation within the Mg system starting with ether-based Mg chloro complex forming electrolytes. Well faceted Mg deposits form in these electrolytes as step-flow growth dominates deposition. Using a combination of chronopotentiometric trace analysis and operando imaging and spectroscopic analysis of the interface during metal addition and removal, we show that interfacial films are responsible for guiding localized dissolution phenomenon that result in cumulative morphology evolution leading to Mg loss with repeated cycling. Interfacial films also play an important role when weakly coordinating anions are used in the place of chloride to deliver the cation to the Mg surface. In these systems, re-nucleation of Mg onto itself plays a dominant role in defining structure and in dictating subsequent efficiency loss. We compare interfacial film composition for several weakly coordinating anions, including bis(trifluoromethylsulfonyl)imide, and contrast film identity and role when chloride anion is present. Lastly, we focus on recent work that explores the role of lithium fluoride – lithium imide salt combinations in ethers at concentrations that yield a solvate electrolyte. Within this system of electrolyte, we probe the role the fluoride film plays in directing Li accommodation and removal from the Li substrate. Loss of dimensional control is probed as a function of local ionic transport within and mechanical properties of the film.
This work is supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE’s NNSA under contract DE-AC04-94AL85000.
11:30 AM - *EE5.4.04/EE6.5.04
Ion Solvation and the Formation of Aqueous Interphase
Liumin Suo 2,Chunsheng Wang 2,Oleg Borodin 1,Kang Xu 1
2 Dept of Chem and Biomolecular Engineering University of Maryland College Park United States,1 US Army Research Lab Adelphi United StatesShow Abstract
Interphase has been the central component that enables battery chemistries of high voltage to reversibly operate, the prominent example of which is the very successful Li-ion 1, 2. The possibility of such a protective interphase has been confined to non-aqueous electrolytes thus far, where the carbonate solvents serve as the main contributor of chemical building blocks of interphase. Recently, we found that by manipulating the inner solvation sphere of Li-ion, one could form such interphase in aqueous electrolytes 3. The expanded electrochemical stability window of such new electrolytes opens new possibilities of aqueous electrochemical devices. In this talk we will examine the criteria for electrolyte components that enables the formation of aqueous SEI as well as the formation mechanism involved.
EE5.5: Lithium-Sulfur and Related Batteries
Wednesday PM, March 30, 2016
PCC North, 100 Level, Room 124 B
1:45 PM - *EE5.5.01
Li-S Batteries: Overview on the Scientific Gap between Fundamental Research and Practical Applications
Jie Xiao 1
1 University of Arkansas Fayetteville United States,Show Abstract
In recent years, lithium sulfur (Li-S) batteries have garnered drastic research interest for both transportation and large-scale (grid) energy storage applications mainly because of this electrochemical couple's high theoretical gravimetric energy density which is projected to be twice that of the state-of-art lithium-ion (Li-ion) batteries and the potential for a greatly reduced battery cost. For practical applications of Li-S batteries, many challenges exist, including poor cycling stability, low round-trip efficiency and severe self-discharge, all of which are rooted in the dissolution of long-chain polysulfide species. The soluble intermediate polysulfides diffuse out of the cathode gradually and “contaminate” almost all of the exposed surfaces in the cell, leading to a series of side reactions and thus poor electrochemical performance.
To overcome the aforementioned hurdles in Li-S batteries, many different approaches have been proposed to modulate the cathode structure, decorate the separator, and alter the interfacial reactions on the anode side of the cell by using new electrolyte recipes or additives. Although the number of publications on Li-S battery research has increased exponentially, still the progress towards the market penetration of Li-S battery is limited. In this talk, an overview will be given on the recent advances in Li-S battery research but focus will be put on the scientific gap between lab R&D and industry need. All the related components in Li-S cells including cathode, electrolyte, separator, anode electrode/electrolyte interfaces and current collector will be reviewed in this talk and future research directions will also be proposed.
2:15 PM - EE5.5.02
High Loading Lithium Sulfur Batteries Achieved through Multi-Functional Binders
Min Ling 1,Changan Yang 1,Hui Zhao 1,Huali Wang 1,Gao Liu 1
1 Lawrence Berkeley National Lab Berkeley United States,Show Abstract
Lithium sulfur (Li-S) batteries may catch up with lithium ion batteries (LIBs) due to its high specific energy and reduced cost from the use of sulfur. Li-S has the highest theoretical specific and volumetric energy densities of any rechargeable battery chemistry (2550 Wh/kg and 2862 Wh/L). The best announced Li-S batteries can offer around 350 Wh/kg and 320 Wh/L currently, which is still significantly better than LIBs (150-200 Wh/kg). The high capacity is based on the conversion reaction of sulfur to form lithium sulfide (Li2S) by reversibly incorporating two electrons per sulfur atom compared to one or less than one per transition-metal ion in insertion oxide cathodes. Sulfur cathode suffers from poor cyclability, which is mainly due to shuttling effect of polysulfides and volume change (ca. 80%). To unlock this potential battery, efforts have been made such as carbon accommodation/coating, electrolyte additives, membrane and lithium anode modification, however, none of them were commercially available until now. Here we propose a total solution based on polymer binders, carrageenan, which is a natural polysaccharide obtained from red seaweeds. Based on the polymer, we build a high areal capacity electrode (ca. 7 mg/cm2) that could buffer the polysulfides shuttle effect and help to maintain the mechanical integrity of the sulfur electrode. A simple, cheap, scalable and versatile way was chosen to obtain sulfur electrodes with high binding capability, the property gain in terms of electrochemical performance (high areal capacity with high current density) is demonstrated, which proves our proposal that an effective binder is one of the key factors to improve the loading of sulfur electrode. This discovery will arouse battery community’s interest in developing advanced green electrode fabrication process for Li-S cells based on binders.
2:30 PM - EE5.5.03
Three-Dimensional Electrodeposition of Li2S and Improved Charge Transport in Dissolved Lithium-Sulfur Batteries Facilitated by Organic Redox Mediators Identified with High-Throughput Computational Screening
Peter Frischmann 1,Laura Gerber 1,Sean Doris 2,Frank Fan 3,Angelique Scheuermann 1,Erica Tsai 1,Xiaohui Qu 1,Anubhav Jain 1,Kristin Persson 1,Yet-Ming Chiang 3,Brett Helms 1
1 Lawrence Berkeley National Lab Berkeley United States,1 Lawrence Berkeley National Lab Berkeley United States,2 University of California Berkeley Berkeley United States3 Massachusetts Institute of Technology Cambridge United StatesShow Abstract
We are in the midst of an electrochemical energy storage boom where rapid development of next-generation battery chemistries is mandatory to keep pace with demand for lower cost, lighter, and smaller batteries that are capable of powering a range of technologies from mobile devices to on-demand delivery of renewable energy to the electric grid. Lithium-sulfur (Li-S) batteries are one promising solution that offer 3-5 times more energy per unit weight, improved safety, and dramatic cost reductions relative to conventional Li-ion batteries. A key component is the sulfur cathode because of its high theoretical capacity (1672 mAh/g), abundance (0.03%), non-toxicity, and low cost 8 and Li2S. Upon discharge a conformal coating of insulating Li2S is deposited on conductive carbon current collectors resulting in large overpotentials and incomplete sulfur utilization. The current paradigm to improve utilization involves higher loadings of high-surface area conductive carbon in cathode formulations where the enhanced utilization is correlated to the engineered micro/mesopores that accommodate additional Li2S electrodeposition.
We have developed a set of organic redox mediators that are electrochemically active in either the soluble regime or precipitation plateau of the polysulfide cathode that mitigate surface area restrictions on current collector design.[1,2] Improved charge transport in the presence of redox mediators results in higher sulfur utilization and in the case of Li2S, an entirely new porous 3-D morphology is observed upon electrodeposition. Our theory guided selection criteria, the mode of operation for the redox mediators, and their effects on Li-S cell performance will be presented.
 Frischmann, P. D.; Gerber, L. C. H.; Doris, S. E.; Tsai, E. Y.; Fan, F. Y.; Qu, X.; Jain, A.; Persson, K. A.; Chiang, Y.-M.; Helms, B. A. “Supramolecular Perylene Bisimide-Polysulfide Gel Networks as Nanostructured Redox Mediators in Lithium-Sulfur Batteries” Chem. Mater. 2015, 27, 6765.
Provisional Patent Application “Electronically Percolating Networks for Redox Flow Batteries” US Patent Application Ser. No: 62/036,056.
 Gerber, L. C. H.; Frischmann, P. D.; Fan, F. Y.; Doris, S. E.; Qu, X.; Scheuermann, A. M.; Persson, K.; Chiang, Y.-M.; Helms, B. A. “3-Dimensional Growth of Li2S in Lithium–Sulfur Batteries Promoted by a Redox Mediator” submitted.
3:15 PM - *EE5.5.04
Comparative Commercial-Viability Evaluation of Rechargeable-Battery Chemistries
Sigita Urbonaite-Trabesinger 1,Petr Novak 1
1 Paul Scherrer Institute Villigen PSI Switzerland,Show Abstract
The demand for rechargeable batteries with high gravimetric and volumetric energy densities will continue to grow, due to the rapidly increasing integration of renewable energy into the global energy scheme. In terms of energy density, modern high-end rechargeable-battery technologies are reaching their fundamental limits and major development leaps are not to be expected in this field. Promising material combinations for near-future non-aqueous rechargeable batteries suitable for portable electronics and automotive applications can be identified using the energy-cost model, which has been developed for the comparative evaluation of battery-cell chemistries in a commercial-type pouch-cell configuration and helps to establish the relationship between cost and energy densities.
Among the wide variety of positive-electrode materials, only few have a sufficiently high potential for commercialization and undoubtedly the immediate future will still be dominated by Li-ion technology, with Li-rich and Ni-rich materials as definite winners, but Li–S and Na-ion chemistries as leading contenders, owing to the low cost and abundance of their key components. Further significant improvements in energy density — be it gravimetric or volumetric — and cost cannot be achieved through the use of new battery chemistries alone. Instead, engineering aspects, targeting cost reduction and safety assurance, will likely be the main driving force of future rechargeable-battery development.
Due to the low cost of raw sulphur and its high theoretical specific charge upon lithiation, the Li–S system, despite its quite narrow potential window, offers the most attractive energy–cost ratio. Also, Li–S batteries can deliver higher gravimetric energy densities than any of their Li-ion counterparts. However, the volumetric energy densities for Li–S systems will at best be on par with state-of-the-art Li-ion batteries. To optimize the performance of the Li–S cell, further engineering efforts are essential, as the Li–S chemistry is exquisitely sensitive to changes in its constituents and in their relative or absolute amounts. We will present an overview of recent advances in the field and will in particular discuss the advantages of introducing standard electrodes and of standardizing testing protocols.
3:45 PM - EE5.5.05
Material Structure Design for Long Cycle Life Lithium-Sulfur Batteries
Hailiang Wang 1
1 Yale Univ West Haven United States,Show Abstract
The rechargeable lithium-sulfur battery is a promising option for energy storage applications because of its low cost and high energy density. The electrochemical performance of the sulfur cathode, however, is substantially compromised due to fast capacity decay caused by polysulfide dissolution/shuttling and low specific capacity caused by the poor electrical conductivities of the active materials.
Recently we have proposed a strategy of utilizing ternay hybrid material structures in which each component takes a different function and synergistically cooperates to reach high electrochemical performance. A hybrid material composed of multi-wall carbon nanotubes (MWCNTs), NiFe2O4 nanosheets and S nanoparticles has demonstrated superior cycling stability together with good specific capacity and rate capability.
We further advance the strategy with a ternary hybrid structured free-standing and flexible cathode composed of single-wall carbon nanotubes (SWCNTs), S nanoparticles and polypyrrole (PPy). The SWCNT-S-PPy flexible cathode can deliever a specific capacity of more than 1200 mAh g-1 at 2 A g-1 with a low decay rate of 0.032% per cycle over 500 recharging cycles, representing the highest electrochemical performance for flexible Li-S battery electrodes.
4:00 PM - EE5.5.06
Hierarchical Particle-Shell Architecture for Long-Term Cycle Stability of Li2S Cathodes
Feixiang Wu 1,Jung Tae Lee 1,Feifei Fan 2,Naoki Nitta 1,Hyea Kim 1,Ting Zhu 2,Gleb Yushin 1
1 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United States,2 Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta United StatesShow Abstract
The ever-increasing energy storage demands of laptops, mobile phones, cameras, electric tools, unmanned aerial vehicles and cars have motivated research on safer, lighter and lower cost rechargeable batteries. Commercial Li-ion batteries utilizing intercalation-type Co- and Ni- containing cathode materials suffer from natural toxicity, relatively high cost and limited specific capacities . Since 2009, the lithium-sulfur chemistry with the high theoretical energy of 2600 Whkg-1 has attracted great attention in the battery community [2-4]. Sulfur with the theoretical capacity of 1675mAh g-1 is abundant in the earth crust, cheap and environmentally friendly. However, the large expansion (~79 vol. %) of S during its lithiation to Li2S may induce mechanical damages within electrodes or S-comprising composite electrode particles, while polysulfide dissolution during cycling induces active material loss and increases cell resistance. Compared with S, the Li2S cathode can pair with the anode materials that do not contain Li, such as C, Si and Sn, and thus offer greatly improved safety.
Here, we reported on the development of a hierarchical particle-shell architecture aimed to enhance long-term stability of the Li2S-based cathodes. Such architecture provides multi-level protection against failure in the protective shelling material. Numerical modeling demonstrated an opportunity to significantly reduce stresses within the outer shell, which should further enhance mechanical stability of the particles and thereby enable effective operation of the electrochemical cells. As an example of the practical hierarchical composite, we synthesized C-Li2S-C particles by using a simple solution-based method followed by carbon outer shell deposition through atmospheric pressure CVD [5-6]. Electrochemical tests showed excellent capacity utilization and rate performance, enabled by embedding Li2S (5-10 nm in size) into conductive material matrix. More importantly, by employing the hierarchical core-shell nanocomposite design, our Li2S cathodes effectively mitigated polysulfide dissolution and achieved remarkable stability within 600 cycles. The hierarchical particle-shell architecture could be applied in many other high-energy volume-changing active materials that could be damaged or dissolved during undesirable interactions with electrolytes.
 D. Andre, S.-J. Kim, P. Lamp, S. F. Lux, F. Maglia, O. Paschos, B. Stiaszny, Journal of Materials Chemistry A 2015, 3, 6709.
 H. D. Yoo, E. Markevich, G. Salitra, D. Sharon, D. Aurbach, Materials Today 2014, 17, 110.
 F. Wu, H. Kim, A. Magasinski, J. T. Lee, H.-T. Lin, G. Yushin, Advanced Energy Materials 2014, 4, 1400196.
 X. Ji, L. F. Nazar, Journal of Materials Chemistry 2010, 20, 9821.
 F. Wu, H. Kim, A. Magasinski, J. T. Lee, H.-T. Lin, G. Yushin, Advanced Energy Materials 2014, 4, 1400196.
 F. Wu, J. T. Lee, F. Fan, N. Nitta, H. Kim, T. Zhu, G. Yushin, Advanced materials 2015, 27, 5579.
4:15 PM - EE5.5.07
Binder-Free, Boron/Nitrogen Heteroatom-Doped Reduced Graphene Oxide for High-Performance Lithium-Sulfur Batteries
Pauline Han 1,Arumugam Manthiram 1
1 University of Texas at Austin Austin United States,Show Abstract
To keep up with the increasing energy demands, lithium-sulfur battery (Li-S) poses itself as the next-generation battery technology due to its high theoretical capacity (1672 mA h g-1). Li-S batteries are promising due to their low cost, high abundance, and benign environmental impact. However, sulfur and the end discharge product (Li2S) are insulating in nature. This, combined with the problem of polysulfide (PS) diffusion, leads to low active-material utilization and limited rate capability. To address these issues, a huge focus has been centered on increasing the conductive performance and localizing PS within the cathode region.
There are many ways scientists have approached this problem, including the use of S-carbon composite materials. Most composites, however, lack sufficient malleability to effectively trap PSs without any substantial impact on the mass energy density of the cell. This presentation introduces light-weight heteroatom boron-doped (B-rGO) and nitrogen-doped (N-rGO) reduced graphene oxide into the cathode architecture as a comprehensive examination into (i) the conductivity that rGO networks provide, (ii) the conductive contribution from the heteroatom dopant, and (iii) the filtering ability that pseudo-stacked heteroatom-doped rGO offers. The graphene network increases conductivity by shortening ion/electron transport pathways while heteroatom doping improves the contact between nonpolar graphene network and the polar PSs. The stacking of the heteroatom-doped rGOs provides enough room for the PS filter to minimize diffusion.
We first present the B/N-doped rGO properties as a binder-free coated separator on a polypropylene membrane (Celgard) and then as a self-supported binder-free PS filter under higher S loadings. As a binder-free filter coated separator, N-rGO was able to attain a peak discharge capacity of 1191 mA h g-1 and a reversible capacity of 849 mA h g-1 over 50 cycles. The similarly prepared B-rGO-coated separator was able to attain a peak discharge capacity of 1027 mA h g-1 and a reversible capacity of 608 mA h g-1 over 50 cycles. Due to the promising performance of binder-free filter-coated separators, S loading was increased in both cell configurations. A B-rGO binder-free self-supported PS filter was able to accommodate a S loading of 4.2 mg cm-2 and attain a peak discharge capacity of 1257 mA h g-1 while maintaining a reversible capacity of 876 mA h g-1 over 50 cycles. As a binder-free self-supported PS filter, N-rGO was able to accommodate a S loading of 3.9 mg cm-2 with a high peak discharge capacity of over 1670 mA h g-1- a value very close to the full electrochemical utilization of S. It is additionally able to maintain a reversible capacity of 1110 mA h g-1 after 50 cycles. Thus, B/N-doped rGOs prove themselves to be a viable material for improving the capacity, cycle stability, and rate capability while accommodating higher S loadings in Li-S cathodes.
4:30 PM - EE5.5.08
X-Ray Absorption Spectroscopy as a Probe of Dissolved Polysulfides in Lithium-Sulfur Batteries
Tod Pascal 1,Kevin Wujcik 2,Nitash Balsara 2,David Prendergast 1
1 Lawrence Berkeley National Lab Berkeley United States,2 Chemical and Biomolecular Engineering UC Berkeley Berkeley United StatesShow Abstract
There has been enormous interest lately in lithium sulfur batteries, since they have 5 times the theoretical capacity of lithium ion batteries1 and already satisfy the energy requirements of the DOE 2020 goals for transportation. Large-scale adoption of this technology has been hampered by numerous shortcomings, chiefly the poor utilization of the active cathode material and rapid capacity fading during cycling. This in turn requires methods capable of identifying and quantifying the products of the poorly understood electrochemical reactions.
One recent advance has been the use of X-ray absorption spectroscopy (XAS), an element-specific probe of the unoccupied energy levels around an excited atom upon absorption of an X-ray photon, to identify the reaction products and intermediates2. In this talk, we’ll present first principles molecular dynamics and spectral simulations of dissolved lithium polysulfide species, showing how finite temperature dynamics, molecular geometry, molecular charge state and solvent environment conspire to determine the peak positions and intensity of the XAS3-5. We’ll present a spectral analysis of the radical (-1e charge) species, reveal a unique low energy feature that can be used to identify these species from their more common dianion (-2e charge) counterparts. The impact of our findings on the proposed LiS discharge electrochemical pathways will be discussed6.
(1) Peramunage, D.; Licht, S. Science 1993, 261, 1029.
(2) Gao, J.; Lowe, M. A.; Kiya, Y.; Abruña, H. D. The Journal of Physical Chemistry C 2011, 115, 25132.
(3) Pascal, T. A.; Pemmaraju, C. D.; Prendergast, D. Physical Chemistry Chemical Physics 2015, 17, 7743.
(4) Pascal, T. A.; Boesenberg, U.; Kostecki, R.; Richardson, T. J.; Weng, T.-C.; Sokaras, D.; Nordlund, D.; McDermott, E.; Moewes, A.; Cabana, J.; Prendergast, D. The Journal of Chemical Physics 2014, 140, 034107.
(5) Pascal, T. A.; Wujcik, K. H.; Velasco-Velez, J.; Wu, C.; Teran, A. A.; Kapilashrami, M.; Cabana, J.; Guo, J.; Salmeron, M.; Balsara, N.; Prendergast, D. The Journal of Physical Chemistry Letters 2014, 5, 1547.
(6) Wujcik, K. H.; Pascal, T. A.; Pemmaraju, C.; Devaux, D.; Stolte, W. C.; Balsara, N. P.; Prendergast, D. Advanced Energy Materials 2015.
4:45 PM - EE5.5.09
Mass Production of Free-Standing Carbon Nanotube Sponges as New Catholyte Reservoir for Li-S Batteries
Gang Yang 1,Xiong Pu 1,Choongho Yu 1
1 Texas Aamp;M University College Station United States,Show Abstract
Li-S batteries are intensively investigated nowadays aiming to replace the commercial lithium intercalation-based Li-ion batteries, due to their higher energy density and lower raw materials price. Nonetheless, several problems have to be well addressed before they are viable for commercialization. First, because of the insulating nature of elemental sulfur and discharge products (e.g. Li2S/Li2S2), large amount of inactive carbonaceous materials or conductive polymers are necessary to lower the ohmic polarization. Second, irreversible sulfur and electrolyte losses during cycling are known to account for the rapid capacity fading and low columbic efficiency. Meanwhile, the deposition or aggregation of solid sulfur and/or Li2S in cathode often makes the active materials inaccessible, deteriorating the cycling and rate performances.
To solve these problems, various approaches have been proposed to trap solid sulfur in micro-/nano-porous structures. However, none of them have been proven to completely prevent the dissolution and shuttling of polysulfides. Contrary to the strategy of avoiding the dissolution of polysulfides, liquid-type polysulfides-containing catholyte has been recently used as active materials. Compared to the sluggish reaction associated with insulating solid-phase sulfur, dissolved polysulfides can alleviate the irreversible deposition of S or Li2S at “dead” sites, and therefore offer a higher utilization of active materials.
Herein, we designed binder-free Li-S batteries with free-standing 3-dimensional networks of carbon nanotube (CNT) sponges, which were used as bifunctional catholyte reservoir and conductive framework in the cathode. The unique microporous structure of the CNT sponge can accommodate a large amount of catholyte as well as form intimate contacts with dissolved redox species in the cathode. Two different catholyte concentrations and loading volumes were used and compared to investigate their effects on battery performances. The electrochemical impedance spectra (EIS) were measured at seven different stages in the first discharge/charge cycle to understand the reaction mechanism of our sulfur batteries. By optimizing the catholyte concentrations and loading volumes, we have achieved a highly stable cycling performance with capacity retention higher than 90% at 0.5-C rate for 300 cycles. According to the impedance spectra during the first discharge/charge cycle along with electron microscopy images, sulfur was uniformly distributed/deposited on the surface of CNT sponge at the fully charged state, and the deposition of solid Li2S2/Li2S at fully discharged state was found to be the rate-determining step. The facile scalable one-step synthesis process of the CNT sponge with inexpensive raw materials used in our sulfur batteries will be a big step toward developing practically viable Li-S batteries in the near future.
Gleb Yushin, Georgia Institute of Technology
Bruce Dunn, University of California, Los Angeles
Arumugam Manthiram, University of Texas at Austin
Linda Nazar, University of Waterloo
SABIC Americas, Inc
Toyota Research Institute of North America
EE5.6: Metal-Oxygen Batteries
Thursday AM, March 31, 2016
PCC North, 100 Level, Room 124 B
8:30 AM - EE5.6.01
Investigations of Transition Metal Oxides (MnOx, Co3O4, RuO2) for Lithium Oxygen Battery Cathodes with DEMS
Dahyun Oh 1,Loza Tadesse 1,Leslie Thompson 1,Ho-Cheol Kim 1,Donald Bethune 1
1 IBM San Jose United States,2 Minnesota State University Moorhead Moorhead United States,1 IBM San Jose United StatesShow Abstract
Transition metal oxides (TMO) have been reported to have a catalytic effect on the oxygen evolution reaction in aprotic Li-oxygen batteries, resulting in lowered charging overpotentials and increased cycling lives. Here, we were able to unravel the role of three TMO’s (MnOx, Co3O4 and RuO2) in the oxidation of Li2O2 using Differential Electrochemical Mass Spectrometry (DEMS). MnOx, Co3O4 and RuO2 particles, synthesized without using any templates, surfactants or ligands, were incorporated in cathodes of Li-oxygen batteries operated with 1 M LiTFSI DME electrolyte to investigate their electrochemical functionalities. First, using our DEMS instrument, we could evaluate the oxygen recovery-to-consumption ratio (OER/ORR efficiency), and relate it to the galvanostatic profile obtained over an electrochemical cycle. In addition, linear sweep voltammetry coupled with mass spectrometry clearly showed two distinguished oxygen evolution stages and how these stages varied with TMO cathodes in charging Li-oxygen batteries. Second, the origin of decomposition of DME in the presence of these TMO’s was studied by discharging cells with 13C based TMO cathodes in an 18O2 environment. The combination of electrochemical and mass spectrometric data allowed us to determine the exact contribution of the TMO cathodes to the ORR and OER reactions. We believe that these results provide a useful guidance for selecting high performance cathode materials by considering all necessary aspects for next generation, high energy density, Li-oxygen batteries.
8:45 AM - EE5.6.02
Limiting Potentials in Mg/O2 Batteries
Jeffrey Smith 1,Donald Siegel 1
1 University of Michigan Ann Arbor United States,Show Abstract
A rechargeable battery based on an Mg/O2 couple presents an attractive chemistry due to its high theoretical energy density and potential for low cost. Nevertheless, many fundamental aspects of this system remain poorly understood, such as the reaction mechanisms associated with discharge and charge. The present study employs first-principles calculations to characterize electrochemical processes on the surfaces of likely Mg/O2 battery discharge products, MgO and MgO2. Thermodynamic limiting potentials for charge and discharge are calculated for several scenarios, including variations in surface stoichiometry and the presence/absence of intermediate species in the reaction pathway. The calculations suggest that pathways involving oxygen intermediates are preferred, as they generally result in higher discharge and lower charging voltages. In agreement with recent experiments, cells that discharge to MgO are predicted to exhibit low round-trip efficiencies, which are rationalized by the presence of large thermodynamic overvoltages. In contrast, MgO2-based cells are much more efficient: high discharge and low charging voltages on oxygen-rich facets result in a round-trip efficiency of approximately 90%. We conclude that the performance of Mg/O2 batteries could be dramatically improved by biasing discharge towards the formation of MgO2 rather than MgO.
9:00 AM - EE5.6.03
Defects Conduction in Sodium Peroxide and Sodium Superoxide
Sheng Yang 1,Donald Siegel 1
1 University of Michigan Ann Arbor United States,Show Abstract
The primary discharge product in sodium−air batteries has been reported in some experiments to be sodium peroxide, Na2O2, while in others sodium superoxide, NaO2, is observed. Importantly, cells that discharge to NaO2 exhibit low charging overpotentials, while those that discharge to Na2O2 do not. These differences could arise from a higher conductivity within the superoxide; however, this explanation remains speculative given that charge transport in superoxides is relatively unexplored. Here, density functional and quasi-particle GW methods are used to comparatively assess the conductivities of Na−O2 discharge phases by calculating the concentrations and mobilities of intrinsic charge carriers in Na2O2 and NaO2. Both compounds are predicted to be electrical insulators, with bandgaps in excess of 5 eV. In the case of sodium peroxide, the transport properties are similar to those reported previously for lithium peroxide, suggesting low bulk conductivity. Transport in the superoxide has some features in common with the peroxide but also differs in important ways. Similar to Na2O2, NaO2 is predicted to be a poor electrical conductor, wherein transport is limited by sluggish charge hopping between O2 dimers. Different from Na2O2, in NaO2 this transport is mediated by a combination of electron and hole polarons. An additional distinguishing feature of the superoxide is its ionic conductivity, which is 10 orders of magnitude larger than the electronic component. The ionic component is comprised primarily of p-type contributions from (surprisingly mobile) oxygen dimer vacancies, and from n-type contributions from negative sodium vacancies. In the context of sodium−air batteries, the low electronic conductivity afforded by NaO2 suggests that enhanced bulk transport within this phase is unlikely to account for the low overpotentials associated with its decomposition. Rather, the enhanced efficiency of NaO2-based cells should be attributed to other factors, such as a reduced tendency for electrolyte decomposition.
9:15 AM - EE5.6.04
Suppression of Electrolyte Degradation via Fluorination: A Case Study for Li-O2 Batteries
Nitin Kumar 1,Donald Siegel 1
1 Department of Mechanical Engineering University of Michigan Ann Arbor United States,Show Abstract
The Li–O2 battery exhibits high theoretical specific energy, making it a promising candidate for energy storage in electric vehicles (EV). One of the main issues hindering the application of these batteries is the decomposition of the organic electrolyte during cycling. This process results in high charging overpotentials, capacity fading, and limited cycle life. Hence, the understanding of these reactions is a crucial step in developing practical Li-O2 batteries. Our prior studies [Kumar et al., J. Phys. Chem. C, 2015, 119(17), 9050-9060] used Van der Waals-augmented DFT calculations to study the initial decomposition reactions of the commonly used electrolyte solvent, DME, on peroxide and superoxide terminated surfaces of the Li2O2 discharge product. We find that a possible degradation reaction route is via hydrogen abstraction from the DME molecule. In addition, DME was found to be more susceptible to undergo chemical decomposition on superoxide terminated surfaces than on peroxide terminations. To improve the stability of the electrolyte we investigate the influence of varying degrees of fluorination of DME (DME-F) on degradation kinetics. A combination of classical Monte Carlo and DFT calculations are used to identify low energy geometries for DME-F adsorption. Activation energies for plausible decomposition pathways are subsequently evaluated. We find that the fluorination reduces the likelihood of electrolyte degradation by increasing the activation energy of hydrogen abstraction.
EE5.7: Metal and Metal-Ion Batteries beyond Lithium I
Thursday AM, March 31, 2016
PCC North, 100 Level, Room 124 B
10:00 AM - *EE5.7.01
Challenges in Mg Battery
John Muldoon 1,Claudiu Bucur 1
1 Toyota Research Institute of N. America Ann Arbor United States,Show Abstract
Without a doubt the Holy Grail of battery research is the development of a post lithium ion technology. This may require a shift towards batteries containing a pure metal anode. Li metal is an attractive metal anode in part due to its high volumetric capacity (2062 mAh cm-3), a high reductive potential of -3.0 V vs. NHE and the wide availability of lithium electrolytes. However, its deposition occurs unevenly with formation of dendrites which leads to safety concerns during cycling. In contrast to lithium metal, magnesium metal deposition is not plagued by dendritic formation. Additionally, magnesium is more stable than lithium when exposed to air, more abundant in the earth crust and provides a higher volumetric capacity (3832 mAh cm-3). However, magnesium has a reductive potential of -2.36 V vs. NHE and has a unique electrochemistry which prohibited the use of magnesium analogues of lithium electrolytes. Since the oxidative stability of electrolytes governs the choice of cathodes it is of paramount importance to develop non-corrosive magnesium electrolyte with wide electrochemical windows which will permit discovery of high voltage cathodes. In this talk we will present the latest developments and future challenges which must be overcome.1,2,3,4,5,6
1. Aurbach, D., Lu, Z., Schechter, A., Gofer, Y., Gizbar, H., Turgeman, R., Cohen, Y., Moshkovich, M. and Levi, E., Nature, 2000, 407, 724-727.
2. Kim, H.S., Arthur, T.S., Allred, G.D., Zajicek, J., Newman, J.G., Rodnyansky, A.E., Oliver, A.G., Boggess, W.C. and Muldoon, J., Nat. Commun., 2011, 2, 427.
3. Muldoon, J., Bucur, C.B., Oliver, A.G., Sugimoto, T., Matsui, M., Kim, H.S., Allred, G.D., Zajicek, J. and Kotani, Y., Energy Environ. Sci., 2012, 5, 5941-5950.
4. Muldoon, J., Bucur, C.B., Oliver, A.G., Zajicek, J., Allred, G.D and Boggess, W.C. Energy Environ. Sci, 2013, 6, 482-487.
5. Muldoon, J., Bucur, C.B. and Gregory. T. Chem. Rev., 2014, 114, 11683-11720
6. Muldoon, J., Bucur, C.B. and Gregory. T. Phys. Chem. Lett., 2015, 6, 3578–3591
10:30 AM - EE5.7.02
Trends in Ligand Modification for Magnesium-Ion Electrolyte Improvement
Carl Nist-Lund 1,Jake Herb 1,Craig Arnold 1
1 Princeton University Princeton United States,Show Abstract
Nonaqueous magnesium-ion battery research has been growing due to the attractive characteristics of such systems, including a high theoretical energy density and, compared to lithium-ion systems, a relatively low cost of materials. Increasing the electronegativity of precursor ligands is an important trend in enhancing the oxidative stability of electrolytes, and thus can enable the use of higher voltage cathode materials.1,2
We have performed electrochemical analysis on a series of solutions made from various magnesium alkoxide and aryloxide compounds in combination with AlCl3 in ethereal solvents. Displaying comparable electrochemical windows, deposition efficiencies, and conductivities compared to previously researched systems, these compounds show a high degree of promise. Additionally, these free flowing alkoxide powder precursors are significantly easier to handle compared to traditional Grignard-based and amido-based magnesium electrolyte precursors. Our work seeks to more fully understand these trends and materials. The synthesis and electrochemical behavior of a series of magnesium alkoxide and aryloxide salts were prepared as precursors for electrolytes for magnesium-ion batteries, and analyzed using cyclic voltammetry and coin-cell measurements.
1. Yoo, H. D.; Shterenberg, I.; Gofer, Y.; Gershinsky, G.; Pour, N.; Aurbach, D.Energy Environ. Sci. 2013, 6, 2265.
2. Nelson, E. G.; Kampf, J. W.; Bartlett, B. M. Chem. Commun. (Camb). 2014, 50, 5193–5195.
10:45 AM - EE5.7.03
Pyrite (FeS2) Nanocrystals as Electrode Material for Sodium-Ion and Sodium/Magnesium-Ion Hybrid Batteries
Marc Walter 1,Tanja Zuend 1,Kostiantyn Kravchyk 1,Maria Ibanez 1,Maksym Kovalenko 1
2 Laboratory of Inorganic Chemistry ETH Zurich Zurich Switzerland,1 Empa - Swiss Federal Laboratories for Materials Science and Technology Dübendorf Switzerland,Show Abstract
Lithium-ion batteries (LIBs) are nowadays the predominant battery technology for portable electronics and are of growing importance in the area of electrical mobility. However, the limited abundance and uneven global distribution of lithium salts are raising concerns regarding future price development and supply security. In this regard, Sodium-ion batteries (SIBs) are gaining increasing attention as more economical alternative, due to the ubiquitous nature of sodium salts. However, especially due to the ~50% larger ionic radius of the Na-ion the electrochemistry of SIBs and LIBs is generally very different and the development of new materials is essential in this field. In fact, many alloying and conversion materials are considered promising candidates as electrode materials for SIBs based on their high specific and volumetric capacities. However, these materials undergo drastic volume changes leading to rapid capacity fading after only a few cycles. In this regard, nanocrystals (NCs) are advantageous electrode materials, since they can improve the cycling stability by mitigating the impact of volume changes. Moreover, as a result of the reduced dimensions and higher surface area, NCs offer faster kinetics compared to their bulk counterparts.
Due to its non-toxicity, low raw material cost and high storage capacity FeS2 so far has been only considered as promising cathode material for LIBs and SIBs. We demonstrate, for the first time, that FeS2 NCs can in fact serve as excellent Na-ion anode material with good cycling stability and rate capability. Namely, FeS2 NCs deliver capacities ≥500 mAhg-1 for 400 cycles at a current rate of 1000 mAg-1 clearly exceeding the performance of both bulk FeS2 as well as various other nanostructured metal sulfides.
Further, we present a hybrid intercalation battery based on a FeS2 NC cathode, metallic magnesium anode and sodium/magnesium dual salt electrolyte.  Unlike lithium or sodium, metallic magnesium can be safely used due to dendrite-free electroplating and offers high volumetric (3833 mAhcm-3) and gravimetric capacities (2205 mAhg-1). Na-ion cathodes – in particular FeS2 NCs – may serve as attractive alternatives to Mg-ion cathodes due fast, highly reversible insertion of Na-ions. In the presented proof-of-concept study, electrochemical cycling of the Na/Mg hybrid battery is characterized by high rate capability, high coulombic efficiency of 99.8% and high energy density. In particular, with an average discharge voltage of ~1.0 V and an average cathodic capacity of 189 mAhg-1 at a current of 200 mAg-1, the presented Mg/FeS2 hybrid battery delivers energy densities of up to 215 Whkg-1. Such a hybrid Na-Mg battery, fully based on Earth-abundant elements, is highly promising for future large-scale energy storage solutions.
 M. Walter, T. Zünd and M. V. Kovalenko Nanoscale, 2015, 7, 9158-9163.
 M. Walter, K. V. Kravchyk, M. Ibanez and M. V. Kovalenko, submitted.
11:00 AM - EE5.7.04
A Binder-Free V2O5 ●0.5H2O Cathode Used in Rechargeable Aluminum Battery
Huali Wang 2,Gao Liu 2,Ying Bai 1,Chuan Wu 1,Shi Chen 1,Daozhou Liu 1,Sichen Gu 1
1 Beijing Institute of Technology Beijing China,2 Lawrence Berkeley National Laboratory Berkeley United States,2 Lawrence Berkeley National Laboratory Berkeley United States1 Beijing Institute of Technology Beijing ChinaShow Abstract
Aluminum is a very attractive material for next-generation energy storage, since it is the most abundant metal in the earth’s crust. Its relatively low atomic weight of 26.98 along with its trivalence give a corresponding electrochemical equivalent of 2.98 Ah/g and a extremely high volume capacity(8.04 Ah/cm3). It is noted that the Al3+ cation has a smaller radius (53.5 pm), which may act as a guest species in intercalation chemistry. Fabrication of rechargeable aluminum battery working at room temperature did not succeed until haloaluminate containing ionic liquids were used as electrolytes. Anions of ionic liquids are expected to have a great effect on performance of rechargeable aluminum batteries. Concentration of Al2Cl7- is considered as a key factor in chloroaluminate ionic liquids when used as electrolytes. Vanadium pentoxide (V2O5) is a favorable candidate as a Na-ion and Al-ion intercalation electrode because of its layered structure, which is open to reversible metal-ion insertion/extraction. Considering acidic AlCl3 contained ionic liquids are not compatible with some binders, a binder-free cathode was synthesized by in-situ hydrothermal deposition of V2O5 on Ni foam current collector, which delivered an initial discharge capacity of 239 mAh/g. An obvious discharge voltage plateau appeared at 0.6 V in the discharge curves of the Ni-V2O5 cathode, which is slightly higher than that of the V2O5 nanowire cathodes with common binders attributing to reduced electrochemical polarization. In comparison with crystalline V2O5, the hydrated form of vanadium pentoxide (V2O5●nH2O) has good chemical stability. Due to the expended interlayer distance, large atomic and molecular species and even polymers can be reversibly intercalated between the layers of V2O5●nH2O. Therefore, it is a very promising strategy to prepare V2O5●nH2O with a particular structure on a conductive substrate, to achieve aluminum battery with good performance by enhancing charge-transfer conductivity and preserving the interface morphology integrity. A simple and clean hydrothermal approach was used for synthesizing a cathode material, consisting of V2O5●0.5H2O nanometer-thick lamella grown on stainless steel mesh. It could effectively maintain the electrode integrity during charge/discharge processes and facilitate the electronic and ionic transportation, with the help of the mechanical strength and the high porosity of the stainless steel mesh. A stabilized capacity of 110 mAh/g under a high current density of 100 mA/g was achieved at 180 cycles.
11:15 AM - EE5.7.05
Surface Phenomena and Characterization of Magnesium Anodes in Prototypical Electrolytes
Jake Herb 1,Craig Arnold 1,Carl Nist-Lund 1
1 Princeton University Princeton United States,Show Abstract
Magnesium-ion batteries represent one possible path to affordable grid level energy storage, due to the high volumetric energy density afforded by metallic magnesium anodes. One of the primary goals of the work being done in this field is the development of electrolytes that are capable of reversible magnesium electrodeposition. Stable electrolytes that possess a large electrochemical window, high cycling efficiency, and compatibility with intercalation-type cathodes are uncommon. Understanding surface phenomena in these systems, particularly with respect to the magnesium anode, is crucial to rational development of future electrolytes. Using a combination of x-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy, we have systematically analyzed how electrolyte composition affects surface structures and elemental makeup of both the magnesium anode and deposits on the counter electrode. By performing long-term tests on sequential generations of electrolytes developed during the past ten years, trends relating electrochemical performance to interfacial phenomena begin to emerge. Factors such as long metallic growths and formation of passivating surface films have a significant impact on the long term performance of cells that use magnesium anodes, and dictate whether a given electrolyte is commercially viable.
EE5.8: Metal and Metal-Ion Batteries beyond Lithium II
Thursday PM, March 31, 2016
PCC North, 100 Level, Room 124 B
1:30 PM - EE5.8.01
Anode Architectures, Anode/Electrolyte Interfaces, and High Energy-Density Anodes for Rechargeable Magnesium Battery Systems
Nikhilendra Singh 1,Timothy Arthur 1,Fuminori Mizuno 1
1 Materials Research Department Toyota Research Institute of North America Ann Arbor United States,Show Abstract
Multivalent battery systems like rechargeable magnesium (Mg) batteries have recently gained more interest as candidate post-lithium (Li) battery systems, for possible applications in electric vehicles (EVs) and plug-in hybrid vehicles (PHVs). This is primarily due to concerns over the range performance of current Li battery systems, and the space requirements for future EVs and PHVs. Mg, being divalent and denser, is theoretically capable of delivering a higher volumetric energy-density (3833 mAh cm-3) than Li (2061 mAh cm-3), making it a viable battery system for addressing current range and space concerns.1-4 To date, various organohaloaluminate electrolytes and electrolytes containing the B-H family have been utilized in Mg batteries, due to the incompatibility of conventional battery electrolytes (TFSI-, ClO4-, PF6-) with Mg metal anodes.3,5 However, as recently reported, it is also possible to use conventional battery electrolytes for Mg-ion batteries, by changing the type of anode, from a Mg metal anode to a Mg-ion insertion-type anode. This change enables Mg-ion transport through the anode/electrolyte interface during the use of conventional battery electrolytes.2-4,6
Here, we report recent advancements in alternate architectures, as well as new materials for insertion-type anodes for rechargeable Mg-ion batteries. Further, we address specific studies related to the observation of the anode/electrolyte interface for Mg batteries, which have recently been studied in some detail.7,8 Results from the utilization of alternate architectures and recent fundamental analytical analyses, focused on studying and understanding the nature of the anode/electrolyte interface, will be presented and discussed.
1 Mizuno F, Singh N, Arthur TS, Fanson PT, Ramanathan M, Benmayza A, Prakash J, Liu Y-S, Glans P-A, Guo J, Frontiers in Energy Research, 2014, 2, 1.
2 N. Singh, T. S. Arthur, C. Ling, M. Matsui and F. Mizuno, Chem. Commun., 2013, 49, 149.
3 Muldoon J, Bucur CB, Gregory T, Chemical Reviews 2014, 114, 11683.
4 T. S. Arthur, N. Singh and M. Matsui, Electrochem. Commun., 2012, 16, 103.
5 Mohtadi R, Matsui M, Arthur TS, Hwang S-J, Angewandte Chemie International Edition 2012, 51, 1.
6 Shao Y, Gu M, Li X, Nie Z, Zuo P, Li G, Liu T, Xiao J, Cheng Y, Wang C, Zhang J-G, Liu J, Nano Letters, 2014, 14, 255.
7 T. S. Arthur, P-A. Glans, M. Matsui, R. Zhang, B. Ma and J. Guo, Electrochem. Commun., 2012, 24, 43.
8 Benmayza A, Ramanathan M, Arthur T, Matsui M, Mizuno F, Guo J, Glans P-A, Prakash J, Journal of Physical Chemistry C, 2013, 117, 26881.
1:45 PM - EE5.8.02
A Facile Microwave-Assisted Technique for Chemical Insertion of Mg and Zn Ions into a Microporous Mo2.5+yVO9+z Cathode for Multivalent-Ion Batteries
Watchareeya Kaveevivitchai 1,Arumugam Manthiram 1
1 University of Texas at Austin Austin United States,Show Abstract
With an aim to increase the energy density and lower the cost, there has been immense interest recently in developing rechargeable batteries based on multivalent working cations, such as Mg2+ and Zn2+. However, it is often tedious to design and develop appropriate host structures for multivalent-ion transport. We present here a new microwave-assisted chemical insertion technique, which has been used successfully to intercalate Mg2+ and Zn2+ ions into microporous Mo2.5+yVO9+z host framework with large open channels. Mo2.5+yVO9+z with tunnels constructed by three-, six-, and seven-membered ring units of MO6 octahedra (M = Mo5+/6+ or V4+/5+) belongs to the family of isostructural MoVNbTeO compounds, which are very active oxidation catalysts for light alkanes due to the redox activities of Mo and V. Mo2.5+yVO9+z has been shown previously to intercalate Li+ ions up to 6 Li per formula unit. With a novel microwave-assisted technique using metal acetates as a metal-ion source and diethylene glycol (DEG) as a reducing agent, divalent-ion-inserted compounds AxMo2.5+yVO9+z (A = Mg and Zn, 0 < x < 3) could be prepared in as little as 30 min at 160 - 200 degrees Celcius. This method provides fast chemical insertion unlike the traditional technique that takes days by using moisture-sensitive organometallic reagents in heptane or hexane, such as di-n-butylmagnesium for Mg2+ and dimethylzinc or diethylzinc for Zn2+. The Mg-inserted compounds MgxMo2.5+yVO9+z (0 < x < 3) thus obtained have been investigated as cathode materials in Mg-ion batteries. Our preliminary results suggest that the inserted Mg2+ ions can be removed electrochemically from the framework and reinserted for many cycles, despite the fact that oxides have higher ionicity compared to sulfides (e.g., Chevrel phases). The crystal structure is found to be well maintained after cycling. This new chemical intercalation process offers a fast, inexpensive, easily scalable method to insert multivalent metal ions using relatively much safer chemicals under ambient atmosphere.
2:00 PM - EE5.8.03
Transforming Two-Dimensional Transition Metal Charcogenides for High Capacity Rechargeable Magnesium Batteries
Yan Yao 2,Yifei Li 1,Hyun Deog Yoo 1,Yanliang Liang 1,Qinyou An 1
1 Univ of Houston Houston United States,2 TcSUH Houston United States,1 Univ of Houston Houston United StatesShow Abstract
Mg rechargeable batteries (MgRBs) stand out as a promising candidate beyond lithium ion battery technologies due to high volumetric energy density, resource abundance, and the dendrite-free deposition behavior of Mg, which ensures safe operation. Many of the advantages of MgRBs originate from the divalent nature and small ionic size of Mg ions; however, these properties also render the cation too polarizing to diffuse easily in most ion-intercalation materials. We recently investigated interlayer expansion as a general atomic-level lattice engineering approach to transform inactive layered intercalation hosts into efficient Mg storage materials. The expansion boosts Mg diffusivity by three orders of magnitude, effectively enabling the otherwise barely active host to approach its theoretical capacity as well as to achieve one of the highest rate capabilities among Mg-intercalation materials. An electrochemical activation method to achieve ~200 mAh/g capacity of Mg intercalation will also be discussed.
2:15 PM - EE5.8.04
P-Block Elements for Rechargeable Mg System: Electrochemical Performance and Structural Characterization
Fabrizio Murgia 2,Ephrem Weldekidan 2,Lorenzo Stievano 2,Laure Monconduit 2,Romain Berthelot 2
1 Equipe Agregats Interfaces Materiaux pour lEnergie Institut Charles Gerhardt de Montpellier (UMR 5253 CNRS Unite de Montpellier) Montpellier France,2 Réseau sur le Stockage Électrochimique de l’Énergie (FR 3459 CNRS) Amiens France,Show Abstract
In order to make available the increasing amount of energy produced by clean and renewable sources at any moment and conditions, cheap, efficient and high-capacity rechargeable systems are needed. Although lithium-ion batteries (LIB) meet these requirements for many applications, the possibility that LIB fulfil the growing demand of more energy-consuming uses is nowadays called into question. Moreover, the future demand of Li seems difficult to satisfy since Li is relatively rare and not evenly distributed on Earth. A strong interest is thus given to alternative solutions and, thanks to its abundance, low price, safety features and high volumetric energy density (3837 mAh/cm3), Mg is today considered as a promising candidate for next-generation energy storage applications. However, only highly air-sensitive electrolytes are compatible with Mg metal that undergoes irreversible passivation with conventional formulations. One of the strategies to overcome this hurdle consists in replacing Mg metal with other materials able to reversibly alloy with Mg, building a veritable Mg-ion battery (MIBs), and allowing the use of safer electrolyte formulations. A few p-block elements (Sn, Sb and Bi) were identified as promising candidates for negative electrodes on MIBs. Following these leading studies, we showed that micron-sized Bi is able to reversibly alloy to Mg (372 mAh/g) even at fast current rates, undergoing a biphasic reaction with the direct formation of well-cristallized Mg3Bi2. Cell capacities recorded during c-rate tests are in line with more elaborate Bi nanotubes. Moreover, ball-milling made Mg3Bi2 was successfully tested in a complete cell and can be set as a promising candidate for next-generation of MiBs. Similar results were obtained for In, which reversibly alloys with Mg (425 mAh/g) at low c-rates exhibiting the lowest alloying voltage ever reported vs. Mg. Fast rate cycling affects the performance of In that suffers of poor kinetics. Operando XRD shows the reversible formation of crystalline MgIn.
To improve the overall performance of the negative electrodes, we recently explored the possible combination of two p-group elements, in order to profit of a synergistic effect between good performance (Bi) and high capacity (In, Sn). The study of these mixed-metal systems and of their electrochemical mechanisms vs. Mg metal, which allows us to explain the observed improvement of their performance compared to pure metals, will be highlighted in this communication.
 J.B. Goodenough, K.S. Park, J. Am. Chem. Soc. 135 (2013) 1167.
 J.-M. Tarascon, Nat. Chem. 2 (2010) 510.
 P. Novák, R. Imhof, O. Haas, Electrochim. Acta 45 (1999) 351.
 F. Murgia, L. Stievano, L. Monconduit, R. Berthelot, J. Mater. Chem. A 3 (2015) 16478.
 Y. Shao, M. Gu, X. Li, Z. Nie, P. Zuo, G. Li, T. Liu, J. Xiao, Nano Lett. 20 (2014) 255.
 F. Murgia, E.T. Weldekidan, L. Stievano, L. Monconduit, R. Berthelot, Electrochem. Commun. 60 (2015) 56.
3:00 PM - EE5.8.05
First-Principles Study of Mg Intercalation in Nanostructured MoO3 Cathode
Liwen Wan 1,David Prendergast 1
1 Lawrence Berkeley National Lab Berkeley United States,Show Abstract
As progress on Li-ion batteries plateaus, safety and material availability continue to be the concerns, particularly as the technology is more widely deployed. Among possible alternatives to Li as a positive charge carrier in batteries, Mg is perhaps most promising. Early-stage cell-level modeling predicts that such systems can provide significantly higher energy density with distinct advantages in safety and material availability. However, one of the main bottlenecks to design better Mg-ion battery system and to achieve comparable performance as Li-ion batteries is to find or develop new cathode materials that can reversibly intercalate Mg-ion while maintaining relatively high intercalation voltage. Earlier pioneering work by Aurbach et al. have shown the applicability of MoO3 thin film as the cathode material to intercalate Mg-ion. In this work, we use first-principles method to show how Mg-ion mobility can be improved in nanostructured MoO3 cathode. Furthermore, creating such nanostructure will inevitably increase the surface/bulk ratio and therefore the behavior of Mg intercalation through the cathode surface is potentially important and may even dominate the kinetics. Here, the Mg desolvation and intercalation mechanisms at different MoO3 surfaces are also studied when the cathode is in contact with active components from the electrolyte.
This work is supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
3:15 PM - EE5.8.06
Renormalization of Electrolyte Energy Levels at Mg-Based Electrodes
Nitin Kumar 1,Donald Siegel 1
1 Department of Mechanical Engineering University of Michigan Ann Arbor United States,Show Abstract
A promising strategy for increasing the energy density of batteries is to substitute a multivalent (MV) metal for the commonly-used lithiated carbon anode. Magnesium (Mg) is one of the prime candidates for a MV battery due to its high volumetric capacity, abundance, and low tendency to form dendrites. However, one of the key issues in the successful implementation of a Mg-based battery is the development of efficient and stable electrolytes. A starting point for the identification of a suitable electrolyte is screening for solvents having a wide enough electrochemical window. This window can be strongly impacted by interfacial interactions with electrodes, resulting in renormalization of the solvent’s HOMO and LUMO levels. This study examines the stability of several common electrolyte solvents (THF, DME, DMSO and ACN) on model electrodes of relevance for Mg batteries: Mg(0001) and MgO(100). Many-body perturbation theory calculations based on the G0W0 method were used to predict shifts in the solvent’s electronic levels during adsorption; trends across the different solvents are discussed. Compared to calculations on isolated molecules, characterization of HOMO/LUMO levels at electrode interfaces presents a more realistic depiction of the stability window of the electrolyte, and can be useful in screening for optimal electrolyte compositions.
3:30 PM - EE5.8.07
Investigation of the NaxMoO2 Phase Diagram from Sodium Electrochemical (de)Intercalation
Laura Vitoux 1,Marie Guignard 1,Francois Weill 1,Matthew Suchomel 2,Jacques Darriet 1,Claude Delmas 1
1 CNRS, Univ. Bordeaux, ICMCB, UPR 9048 Pessac France,2 Argonne National Laboratory, Advanced Photon Source Lemont United StatesShow Abstract
Research on sodium layered oxides NaxMO2 (M: 3d or 4d transition metal, x: sodium content) as positive electrode in sodium ion batteries have regained interest for stationary energy storage applications. Furthermore, due to their structure, in which sodium occupy interstitial sites (octahedral or prismatic) between [MO2] slabs constituted of MoO6 edge-sharing octahedra, sodium layered oxides can exhibit original physical properties depending on their chemical composition (nature of the transition metal and sodium content).
This work focus on NaxMoO2 layered oxides, which have been the subject of only a few publications in the 1980’s concerning Na2/3MoO2 [1-4], and Na0.5MoO2 . The only electrochemical investigation , shows a reversible sodium intercalation in NaxMoO2 for 0.28
3:45 PM - EE5.8.08
Sodium Intercalation Mechanisms into Corrugated Titanate Structures for Na-Ion Batteries
Isaac Markus 2,Mona Shirpour 2,Simon Engelke 2,Siafung Dang 3,Marco Prill 3,Robert Spatschek 3,Mark Asta 1,Marca Doeff 2
1 Material Science and Engineering UC Berkeley Berkeley United States,2 Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley United States,2 Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley United States3 IEK2 Forschungzentrum Jülich Julich Germany1 Material Science and Engineering UC Berkeley Berkeley United StatesShow Abstract
Sodium ion batteries (SIBs) are one of the most promising technologies for grid storage due to the large abundance of sodium in the earth’s crust. Grid scale storage must not only be available at a low cost but must also be based on materials that are abundant enough to cover the scale of future energy consumption. SIBs have the additional advantage that they can utilize many of the manufacturing and processing techniques used by current lithium ion batteries. However, SIBs still face challenges related to energy density given that graphite is not able to intercalate high amounts of sodium. As an alternative, sodium titanates are attractive anode materials for SIBs due to their rich range of crystal structures that can reversibly intercalate sodium ions.
In this work we investigated two types of titanates that have been recently synthesized and tested. The first is based on Na1+xTi3O6(OH)×2H2O, known as sodium nonatitanate1, and the second is based on the lepidocrocite structures, Na0.8Ti1.73Li0.27O4 and Na0.8Ti1.4Mg0.6O42. Using density functional theory (DFT) we computed the structural changes during sodiation, and calculated voltage profiles for the different materials. We also calculated changes to the sodium diffusion energy barriers at different sodium concentrations. Structural results indicate that sodium intercalation is a site-limited process in both sets of titanates, with energy barriers increasing during sodiation.
Experiments on the phase stability of these compounds are underway employing coulometric titration and differential scanning calorimetry. Because Na2Ti3O7 has been shown to undergo phase relaxation with increasing sodium content3, we seek to understand if other titanates are also susceptible to phase changes during sodiation. Thermal stability results indicate that for both sets of materials the pristine and sodiated structures are stable up to at least 500o C. Current efforts are focused on detecting if the materials undergo phase relaxations at discharge conditions.
1. Shirpour M., Cabana J., Doeff M. “New materials based on a layered sodium titanate for dual electrochemical Na and Li intercalation systems”, Energy Environ. Sci., 6, 2538 (2013).
2. Shirpour M., Cabana J., Doeff M. “Lepidocrocite-type Layered Titanate Structures: New Lithium and Sodium Ion Intercalation Anode Materials.” Chemistry of Materials 2014 26 (8), 2502-2512.
3. Xu J., Ma C., Balasubramanian M., Meng Y.S. “ Understanding Na2Ti3O7 as an ultra-low voltage anode material for a Na-ion battery.” Chem. Commun. 2014, 50, 12564-12567.
EE5.9: Poster Session II: Next-Generation Supercapacitor Materials and Devices
Thursday PM, March 31, 2016
Sheraton, Third Level, Phoenix Ballroom
8:00 PM - EE5.9.01
Light-Weight Nitrogen-Doped Hierarchically Porous Carbon Foam for Energy Storage Devices
Jizhang Chen 1,Ni Zhao 1,Ching-Ping Wong 2
1 Department of Electronic Engineering The Chinese University of Hong Kong Shatin, New Territories Hong Kong,1 Department of Electronic Engineering The Chinese University of Hong Kong Shatin, New Territories Hong Kong,2 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United StatesShow Abstract
Free-standing three dimensional (3D) carbonaceous materials have emerged as a promising type of materials, owing to their advantages such as self-support, great flexibility and compressibility, high electronic and thermal conductivities, high chemical stability, and large amount of interconnected macropores. These materials have shown attracting performances for a variety of applications, such as electrochemical electrodes (e.g. for supercapacitors, batteries, fuel cells, and solar cells), absorbers, and matrixes for sensors and thermal energy storage. Current synthesis methods for free-standing 3-D carbon are either time-consuming and complicated or uncontrollable. In this study, we address this problem through developing a facile, scalable, and cost-effective strategy to fabricate hierarchically porous carbon foam (HP-CF) by directly annealing home-made melamine foam. The HP-CF serves as an excellent material for supercapacitors owning to its multiscale, interconnected porous morphology as well as the proper density that ensures not only a high gravimetric capacitance but also a high volumetric capacitance. Moreover, the HP-CF can be used as the current collector and mechanical matrix to support pseudocapacitive materials, so that asymmetric supercapacitors (ASC) can be assembled. In the ASCs, the 3-D interconnected hierarchically porous architecture allows for rapid and efficient ionic transport, while the continuous carbon matrix provides sufficient transport routes for electrons. As a result, the obtained ASC devices exhibit both high energy and high power. Importantly, the HP-CF is much lighter and more flexible than conventional Ni foams. All these