Shyue Ping Ong, University of California, San Diego
Byoungwoo Kang, POSTECH
Jeff Sakamoto, University of Michigan
Kang Xu, U.S. Army Research Laboratory
Army Research Office
EN06.01: Safe and Energy-Dense Batteries
Shyue Ping Ong
Tuesday AM, April 03, 2018
PCC North, 100 Level, Room 121 B
10:30 AM - EN06.01.01
Can Multi-Electron Intercalation Reactions be the Basis of THE Next Generation Batteries?
M. Stanley Whittingham1,Carrie Siu1,Jia Ding1
State University of New York at Binghamton1Show Abstract
Intercalation compounds form the basis of essentially all lithium rechargeable batteries. They exhibit a wide range of electronic and crystallographic structures. The former varies from metallic conductors to excellent insulators. Today’s lithium batteries are limited in capacity, because less than one lithium ion is reversibly intercalated per transition metal redox center. There may be an opportunity to increase the storage capacity by utilizing redox centers that can undergo multi-electron reactions. This might be accomplished by intercalating multiple monovalent cations or one multivalent cation. In this talk we will review the key theoretical and experimental results on lithium and magnesium reversible intercalation into two prototypical materials: titanium disulfide, TiS2, and vanadyl phosphate, VOPO4. Both of these materials exist in two or more phases, which have different molar volumes and/or dimensionalities and thus are expected to show a range of diffusion opportunities for battery active guest ions such as lithium, sodium, and magnesium. A major conclusion of this research is that reversibly intercalating two lithium or sodium ions into a host lattice whilst maintaining it’s crystal structure is possible. A second major conclusion is that theoretical studies are now sufficiently mature that they can be relied upon to predict the key free energy values of simple intercalation reactions, i.e. the energy that might be stored. This could help to focus future choices of battery couples.
This work was supported as part of NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583.
11:00 AM - EN06.01.02
Design of Positive Electrode Layers for All-Solid-State Rechargeable Batteries with High Energy Density
Akitoshi Hayashi1,Atsushi Sakuda1,Masahiro Tatsumisago1
Osaka Prefecture University1Show Abstract
All-solid-state rechargeable Li or Na batteries attract much attention because of their high safety, long cycle life, versatile geometry and high energy density. Sulfide solid electrolytes based on the system Li2S-P2S5 have several advantages of high conductivity, wide electrochemical window, and appropriate mechanical properties suitable for forming close solid-solid interfaces with electrode active materials. Dense sulfide electrolyte pellets with about 90% relative density are prepared by only mold-pressing at room temperature without any sintering at high temperatures. To increase energy density of the batteries, the use of positive electrode active materials with high capacity and the increase of their content in a positive electrode layer are desired. Formation of favorable and large contact areas between electrode and electrolyte is achieved by electrolyte coating on electrode particles via gas-phase or liquid-phase techniques. Sulfide amorphous electrolyte coating on LiCoO2 particles by pulsed laser deposition is effective in increasing reversible capacity of all-solid-state batteries. Closely-attached electrolyte-LiCoO2 interfaces with large contact area are achieved by electrolyte coating. The coating reduces the volume of electrolyte content in an electrode layer, and energy density of solid-state batteries is thus increased. Preparation of nanocomposite electrodes with solid electrolytes and nano-carbons by high-energy ball milling is useful for sulfur or Li2S active materials. Conductivity enhancement of Li2S by the combination of LiI contributes to the improvement of utilization of Li2S active material in all-solid state batteries. Amorphous transition metal sulfides such as amorphous TiS3 are attractive as a mixed conductor with large capacity, and all-solid-state Li and Na batteries with high energy density are achieved.
Ref. A. Hayashi, A. Sakuda and M. Tatsumisago, Front. Energy Res., 4, 25 (2016).
11:30 AM - EN06.01.03
Li-Ion Transport Modeling in Amorphous Solid Electrolytes
Boris Kozinsky1,2,Mordechai Kornbluth1
Robert Bosch LLC1,Harvard University2Show Abstract
With recent industry-wide investments into electric vehicles, much research & development has focused on designing safer, lighter, fast-charging batteries. In particular, researchers search for an electrolyte that is manufacturable, mechanically robust, dendrite-resistant, and ionically conductive. The success of LiPON thin films indicates promise in glassy and amorphous materials, which are known to have different transport properties than their crystalline counterparts.
With computational atomistic study of ionic transport mechanisms, we develop mechanistic understanding and design rules for new glassy electrolytes. Using molecular-dynamics simulations, we model Li-ion conduction in various families of crystalline and amorphous materials. In particular, we identify the effects of structure amorphization on ionic conductivity and correlation.
This work is partially supported by the Advanced Projects Research Agency - Energy (ARPA-E), U.S. Department of Energy, and by the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy.
EN06.02: Electrode-Electrolyte Interfaces
Shyue Ping Ong
M. Stanley Whittingham
Tuesday PM, April 03, 2018
PCC North, 100 Level, Room 121 B
1:30 PM - EN06.02.01
Unlocking High Voltage Stability in all Solid State Batteries
Samsung Electronics1Show Abstract
Recent computation and experimental works have discovered a remarkable array of materials with superionic conductivities that rival or exceed the conductivity of conventional liquid electrolytes such as Li and Na conducting NASICON-type oxides, Li garnets, lithium-rich anti-perovskites, and thiophosphate materials. Unfortunately, the high ionic conductivity often is associated with a penalty of high impedance at interfaces between electrolyte and electrodes; this interfacial impedance can dominate the internal resistance in many systems. High impedance is found both in thiophosphate electrolytes in contact with oxide cathodes and during high temperature processing of oxide electrolytes cosintered with oxide cathodes. Because of the necessity of maintaining low interfacial impedance for high power applications, we have focused on understanding the reactions occurring at the various interfaces. This talk will focus on the development and implementation of computational thermodynamic methods to predict trends in reactivity and types of reaction products formed at the interfaces of a number of commonly investigated electrolyte systems, cathode materials, and cathode coatings. We use these results to identify combinations of materials that are thermodynamically stable over the range of processing and operating conditions experienced in high voltage all solid state battery systems.
2:00 PM - EN06.02.02
Formation and Stability of Solid Electrolyte-Electrode Interfaces Probed by Electron Microscopy
Miaofang Chi1,Xiaoming Liu1,Jeff Sakamoto2,Nancy Dudney1
Oak Ridge National Laboratory1,University of Michigan2Show Abstract
Advances in solid electrolytes and their interfaces represent major challenges for the development of future energy storage. An ideal solid electrolyte material must not only be highly ionically conductive but also exhibit desirable stability with metallic lithium and cathodes. While several new solid electrolyte materials have been developed that demonstrate high conductivity, little is known about their integration with electrodes. Unexpected high resistivity is often observed at solid electrolyte-electrode interfaces. Understanding how solid-solid interfaces are formed and how mass transport and charger transfer occur at these interfaces are crucial to the design of interfaces with high electrochemical performance. Many solid electrolytes are polycrystalline and contain significant amounts of grain boundaries that often exhibit completely different structure and chemistry from that of bulk grains. Particular attention has to be paid to the electrochemical stability of the grain boundaries that are exposed to the interfaces with electrodes. However, experimentally probing these embedded interfaces is challenging. Here, in situ and atomic-resolution scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) are used to study these interfaces. Al-Li7La3Zr2O12 (LLZO) and LLTO were used as model systems. In order to understand the crystalization mechanism of amorphous LCO on LLTO, phase evolution and chemical diffusion at the interface of LLTO with sputtered amorphous LiCoO2 were monitored in situ during thermal annealing. The competing elemental diffusion and crystallization were vividly revealed. At the interface of LLZO with Li metal, we focused on understanding how different types of grain boundaries response to the contact of Li metal both in a static state and upon an electrical bias. Our microscopy results provide valuable insights into the design and synthesis of solid electrolyte – electrode interfaces.
Research sponsored by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy. Microscopy performed as part of a user project at Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE User Facility.
3:30 PM - EN06.02.03
Mechanical Properties of Lithium—Past, Present and Future
Alvaro Masias1,2,Jeff Sakamoto2
Ford Motor Company1,University of Michigan2Show Abstract
The recent resurgence of electrified vehicle product introductions seen in recent years has been enabled by meaningful advances in lithium ion batteries. This technology’s specific energy (Wh/kg) has improved steadily at nearly 8% per year. The achievement and maintenance of this specific energy growth rate has been the result of large, long term investment in improved battery research, development and manufacturing. However, to significantly promote the displacement of petroleum fuels from the transportation sector, a step increase in battery performance is necessary.
Solid state (SS) batteries are one of the most versatile and promising approaches of the various technologies under development for next generation energy storage. By enabling the use of high energy lithium metal anodes, SS batteries can enable major improvements in energy density. An approximately 50% gain in cell energy density is possible if SS electrolytes of comparable thickness to incumbent polyolefin separators could be developed to use metallic lithium anodes . However, despite research efforts for more than 50 years, the mechanical properties of lithium metal are not well known.
A SS electrolyte material must fulfil various physical and chemical requirements to perform successfully in the battery environment. For example, some SS electrolytes have shown a tendency to allow for lithium dendrites to penetrate its structure once a critical charge density (CCD) has been reached . Main of these requirements are driven by the need to conduct and contain lithium metal anodes and yet relatively little is known of the physical properties of this metal. A review of previous efforts to characterize the mechanical elastic constants, elastic and plastic deformation limits of metallic will be shown and compared to new bulk empirical results . Additionally, the particular mechanical requirements of the battery environment will be discussed and future mechanical targets introduced.
 McCloskey, B. et al. J Phys. Chem. Lett. 6 (2015) 4581-4588.
 Sharafi, A. et al. J. Power Sources, 302 (2016) 135-139.
 Masias, A et al. ECS Fall Conf. (2017) Abs #205.
4:00 PM - EN06.02.04
Design of Materials for Safe High Rate Capability Batteries
National Univ of Singapore1Show Abstract
Li+ and Na+-ion conductors not only control the performance of all-solid-state-batteries but are also key components in large-scale metal-air, metal-sulfur, and alkali-redox flow batteries. Therefore, designing new and optimizing known ion conductors is crucial for enabling large-scale energy storage systems with high rate performance. The redevelopment of the crystal chemical bond valence approach into our energy-scaled “bond valence site energy” method  allows for computationally cheap predictions of ion migration pathways and migration barriers from static structure models and thus for high-throughput screening of wide ranges of candidate compounds as alkali ion or mixed conductors with balanced conductivity and stability. As a transferable effective forcefield for MD simulations it helps to analyze ion transport mechanisms, as exemplified here by a discussion of differences between alkali ion migration in superionic Li10GeP2S12 and Na10GeP2S12, explaining why the latter is, despite contrary predictions from ab initio MD simulations, only a moderate Na+ conductor. To overcome fundamental limitations of two-body forcefields, it will also be discussed how the approach can be augmented to an EAM-type multibody forcefield with bond valence sum-based embedding function.
As the ionic conductivity in mixed conductors also controls the achievable rate performance of insertion electrode materials, we extended our combined ab initio and empirical bond valence analyses to alkali-ion cathode material structures, demonstrating a simple structure property relationship that yields from the structure a quantitative prediction of the characteristic (dis)charge rate up to which a material (with given particle size) can be expected to deliver high capacity.
Experimentally we aim to establish rationally optimized processing for solid electrolytes and electrode materials by in situ X-ray or neutron monitoring of the formation process. Thereby we not only achieve phase pure high performance materials with well-controlled dopant contents in a cost and energy-efficient way, but provide deeper understanding of the formation mechanisms and kinetics of the desired phase as well as of potential impurities. We tested our predictions by the realization of all solid state Na+-ion batteries with high rate performance at room temperature  and of high energy efficiency aqueous Li-air batteries (LABs) using scalable fast-ion conductor membranes.[5,6]
 H. Chen, S. Adams, IUCrJ 4 (2017) 614-625.
 L.L. Wong, H. Chen and S. Adams; Phys. Chem. Chem. Phys. 19 (2017) 7506.
 R. Prasada Rao, W. Gu, N. Sharma et al.; Chem. Mater. 27 (2015) 2903.
 R. Prasada Rao, H. Chen, L.L. Wong and S. Adams; J. Mater. Chem. A 5 (2017) 3377.
 D. Safanama, S. Adams, J. Power Sources 340 (2017) 294; ACS Energy Lett. 2 (2017) 1130.
 Y.G. Zhu, Q. Liu, Y. Rong, H. Chen et al.; Nature Comm. 8 (2017) 14308.
EN06.03: All-Solid-State Batteries
Tuesday PM, April 03, 2018
PCC North, 100 Level, Room 121 B
4:30 PM - EN06.03.01
Enhancing Interfacial Stability Between the Solid Electrolyte and Sodium Metal Anode via Polymer Interlayer
Yan Yao1,Ye Zhang1
University of Houston1Show Abstract
Rechargeable sodium-ion batteries have received growing attention as promising alternatives to lithium-ion batteries because of the abundance of Na resources as well as its high theoretical capacity of 1165 mAh/g, and low electrochemical potential (-2.71 V vs. standard hydrogen electrode). However, the safety issues remain as the most critical problems for its application. The rise of sulfide-based solid state electrolytes (SSEs) with high Na-ion conductivity have brought about new opportunities for the development of sodium metal batteries. Compared to organic electrolytes, the inorganic SSEs have an increased Young's modulus, which suppress stress points in the metal anode to prevent dendrite formation. Additionally, the SSEs are non-flammable, which addresses the safety concern posed with the organic electrolyte.
Despite the high ionic conductivities of sulfide-based SSEs, most of them are not stable with a metallic sodium anode. The recently investigated tetragonal Na3SbS4 having a superior Na-ion conductivity up to 3 mS/cm at room temperature is a good candidate for SSE, but it also suffers from poor chemical stability with Na. Based on theoretical calculation and experimental results, we find Na3SbS4 is not stable with Na metal and will decompose into Na2S and Na3Sb, resulting in a significant increase of interfacial resistance. Our approach for stabilizing the Na3SbS4/Na interface is to introduce a cellulose-supported poly(ethylene oxide) (CPEO) layer between Na3SbS4 and Na. Owing to the high stability of the CPEO layer and the enhanced interfacial contact with Na, the Na/CPEO/Na3SbS4/CPEO/Na symmetric cell shows a stable Na stripping/plating over 800 hours under 0.1 mA/cm2 at 60 oC. This simple and scalable polymer protecting approach provides a solution to improve the anode stability of sulfide-based electrolyte.
4:45 PM - EN06.03.02
Modification of Grain-Boundary to Suppress Lithium Growth Through Garnet-Type Solid Electrolyte
Hirotoshi Yamada1,Rajendra Hongahally Basappa1,Tomoko Ito1
Nagasaki Univ1Show Abstract
Garnet-based lithium ion conducting solid electrolyte, with nominal composition Li7La3Zr2O12, is a promising solid electrolyte for all solid-state batteries due to its high Li-ion conductivity and stability with lithium metal anode . However, lithium dendrite growth during lithium deposition on the negative electrode causes short-circuit with increasing current density [2, 3]. In this work, we prepared garnet-based Li6.5La3Zr1.5Ta0.5O12 (LLZT) pellets, with different synthesis conditions, and investigated correlation between the pellet structure and short-circuit prevention.
LLZT powder and pellets were prepared using a solid-state reaction and spark plasma sintering technique, respectively, as reported in our previous work . The prepared pellets are designated as LLZT-air (conventional method), LLZT-w/o-air (without exposing to air), and LLZT-2calc (calcined twice with addition of LiOH) . A combination of structural and chemical characterization techniques, such as scanning electron microscopy and fourier transform infrared spectroscopy, revealed presence of LiOH and Li2CO3 on the LLZT powder and effects of excessive lithium salt on the microstructure of the pellets. To investigate the short-circuit prevention, symmetric cells of Li | LLZT | Li were assembled. The cells were cycled at various current densities (1 hour per cycle) at 25°C, which were gradually increased until the cells showed voltage drop [2, 3]. Direct current (DC) polarization curves demonstrate that the voltage fluctuation during cycling increased, as the current density increased. This is due to reduced effective electrode area because voids were formed by the Li dissolution at the Li | LLZT interface. The critical current density (CCD), at which voltage drop occurred, depended on the specimens. LLZT-2calc exhibited the highest CCD of 0.6 mA cm−2, while LLZT prepared without exposing to air showed rather poor short-circuit prevention (CCD of 0.15 mA cm−2). This suggests that Li2CO3 and/or LiOH on surface of starting LLZT powder is effective to improve density of grain boundaries in the pellets to suppress the short circuit. Microstructural analysis and detailed electrochemical impedance analysis demonstrated that Li2CO3 and LiOH not only facilitate sintering on the grain boundary, but also physically suppress the lithium growth by filling voids among LLZT grains .
 R. Murugan, V. Thangadurai, W. Weppner, Angew. Chem. Int. Ed. 46 (2007) 7778.
 H. Yamada, T. Ito, R. Hongahally Basappa, Electrochim. Acta 222 (2016) 648.
 R. Hongahally Basappa, T. Ito, H. Yamada, J. Electrochem. Soc. 164 (2017) A666.
 R. Hongahally Basappa, T. Ito, T. Morimura, R. Bekarevich, K. Mitsuishi, H. Yamada, J. Power Sources 363 (2017) 145.
EN06.04: Poster Session I
Tuesday PM, April 03, 2018
PCC North, 300 Level, Exhibit Hall C-E
5:00 PM - EN06.04.01
High Capacity All-Solid-State Sodium Metal Battery with Hybrid Polymer Electrolyte
Yongwei Zheng1,Qiwei Pan1,Mallory Clites1,Bryan Byles1,Ekaterina Pomerantseva1,Christopher Li1
Drexel University1Show Abstract
Recently, sodium has reattracted scientists' interest in using in rechargeable battery for its low cost and abundant amount compared with lithium. All-solid-state sodium metal battery is doomed to have promising future for its theoretically high capacity (1166mAh/g), non-flammability and low cost. Here, we fabricated a polyethylene oxide (PEO) based hybrid solid electrolyte which showed low glass transition temperature, absence of crystallization and ionic conductivity greater than 1×10-4 S/cm at 80 °C. The solid electrolyte showed low interface resistance (~100ohms at 80C) with sodium metal and high stability in cycling test, with Cd reaching 3000C/cm2 at current density 0.5mA/cm2. All-solid-state sodium metal battery using thermal-treated vanadium oxide as active material, the hybrid polymer as the electrolyte and separator, and pristine sodium metal as the anode. The battery showed excellent capacity (300mAh/g) and good coulombic efficiency. Detailed sodium dendrite growth and electrolyte depletion in have also been systematically studied. Our work showed that the hybrid network is promising for all-solid-state sodium battery applications.
5:00 PM - EN06.04.02
Ion Beam Irradiated Graphenic Layers as Lithium Ion Battery Anodes
Prateek Hundekar1,Shravan Suresh1,Rajesh Kumar1,Nikhil Koratkar1
Rensselaer Polytechnic Institute1Show Abstract
We present a study to understand the role of defects in enhancing the charge capacity of many layered graphene by gradually increasing the defect concentration in a pristine graphene sample by ion beam irradiation. An Ar+ ion beam with energies of 50-105 KeV was used to engineer defects by varying the penetration depth of the ion beam in the sample. Electrochemical cycling of these defective graphenic layers against Li metal foil showed a correlation between the specific charge capacity and the energy of the irradiated ion beam used to create defects. The charge capacity was found to increase to 440mAh/g compared to the charge capacity of a pristine many layered graphene sample of 250mAh/g after 100 cycles. The charge capacity however, doesn't increase linearly with the energy of the Ar+ ion beam but tends to decrease after an optimum value that can be attributed to the distribution of the created defects in the sample.
5:00 PM - EN06.04.03
Polymer-Assisted Deposition Li(Ni,Co,Mn)O2 Thin Films
Di Huang1,Qi Zhou1,Christopher Catanach1,Hongmei Luo1
New Mexico State University1Show Abstract
Rechargeable lithium-ion batteries are widely used in mobile devices, hybrid, plug-in hybrid, and electric vehicles. The performance of batteries strongly depends on the structure, morphology, and properties of electrode materials. A great effort has been made to synthesize a variety of electrode materials and to understand the role of the electronic structure of redox active materials to improve the energy density, rate capability, and cycling stability. It is generally considered that positive electrode determines the specific capacity and the energy density of batteries. Li(Ni,Co,Mn)O2, a layered material, has gained considerable attention as the positive electrode due to its high specific capacity and thermal stability. To understand the nature of the electrochemical reaction, it is expected that single crystal-like electrode materials may offer better understanding of its effects on crystallographic orientation on the electrochemical properties. To this end, epitaxial Li(Ni,Co,Mn)O2 thin films of different orientations have been successfully grown on SrTiO3 substrates from a solution method, called polymer-assisted deposition. The films have been characterized by x-ray diffraction, atomic force microscope, and cross-section high resolution transmission electron microscope.
5:00 PM - EN06.04.04
Atomic-Scale Control of Silicon Expansion Space as Ultrastable Battery Anodes
Hunan University1Show Abstract
Development of electrode materials with high capability and long cycle life are central issues for lithium ion batteries (LIBs). Here, we report an architecture of three-dimensional (3D) flexible silicon and graphene/carbon nanofibers (FSiGCNFs) with atomic-scale control of the expansion space as the binder-free anode for flexible LIBs. The FSiGCNFs with Si nanoparticles surrounded by accurate and controllable void spaces ensure excellent mechanical strength and afford sufficient space to overcome the damage caused by the volume expansion of Si nanoparticles during charge and discharge processes. This 3D porous structure possessing built-in void space between the Si and graphene/carbon matrix not only limits most solidelectrolyte interphase formation to the outer surface, instead of on the surface of individual NPs, and increases its stability but also achieves highly efficient channels for the fast transport of both electrons and lithium ions during cycling, thus offering outstanding electrochemical performance (2002 mAh g−1 at a current density of 700 mA g−1 over 1050 cycles corresponding to 3840 mAh g−1 for silicon alone and 582 mAh g−1 at the highest current density of 28 000 mA g−1).
5:00 PM - EN06.04.05
The Studies of Lattice Parameter and Electrochemical Behavior for Li3V2(PO4)3/C Cathode Materials
Min-Young Kim1,Seung-Woo Choi1,Da-Hye Kim1,Seung-Hoon Yang1,HaYoung Jung1,Hye-Min Ryu1,Sang-Jun Park1,Ho-Sung Kim1
Korea Institute of Industrial Technology1Show Abstract
Single-phase, nano-sized Li3V2(PO4)3/C materials with the monoclinic structure were prepared by a modified sol-gel method, in which the precursor materials were sintered at 750, 800, 850 and 900 °C, respectively. The X-ray diffraction(XRD) patterns of all the materials were consistent with the monoclinic structure without any impurities. The LVP/C composite sintered at 800 °C was selected as the most promising material on the basis of the lattice parameters (a = 8.605 Å, b = 8.596 Å, c = 14.732 Å, b = 125.20 °, V = 890.59 Å3), crystallite size (99 nm), and morphology (5−6 nm carbon layer). The LVP/C composite sintered at 800 °C showed a high specific capacity with excellent kinetic properties (capacity of 130 and 170 mAh*g-1 at voltages of 3.0-4.3 and 4.8 V at 0.1 C, 25 °C ), which showed about 98%, 86% of its theoretical capacity, respectively.
5:00 PM - EN06.04.06
Observation of Interfacial Dynamics in Magnesium Batteries Using Operando XAS/TEM
Khim Karki4,Timothy Arthur1,Per-Anders Glans2,Nikhilendra Singh1,Oscar Tutusaus1,Yi-Sheng Liu2,Fuminori Mizuno1,Jinghua Guo2,3,Daan Alsem4,Norman Salmon4,Rana Mohtadi1
Toyota Research Institute of North America1,Lawrence Berkeley National Laboratory2,University of California3,Hummingbird Scientific4Show Abstract
There has been a considerable interest in the battery system beyond lithium-ion. Magnesium-based systems remain the stronger candidate because of their earth abundance, and their ability to use Mg-metal as anode, which has been shown to deposit non-dendritically, a major impediment for realization of Li-metal system. However, the role of the surface passivating film (SEI) in the deposition/stripping of Mg at the anode/electrolyte interface during the reversible charge/discharge cycle has not been fully explored. For example, some borohydride-based electrolytes such as Mg(BH4) suffer from lower oxidative potential (1.7v vs. Mg), and are prone to undergo electrochemical changes in the anode/electrolyte interface during cycling. Combined operando approaches using electrochemical-synchrotron soft X-ray absorption (sXAS) and transmission electron microscopy (TEM) provide perfect platforms to observe such representative electrochemical processes in great details.
Both sXAS and TEM utilize operando electrochemical cell consisting of microfabricated Si3N4 window and Pt electrode contacts. In sXAS, two additional electrode – Mg foil and a platinum wire are inserted, and the electrochemical interface at the thin Pt layer is probed. In TEM, the enclosed liquid cell consisting of Pt electrode electrochemistry chips is supplied with a continuous flow of electrolyte with a gas tight syringe, and cyclic voltammograms are recorded at 2 mV/s. All TEM analysis are performed using a JEOL JEM-2100 operating at 200kV, and a liquid electrochemistry is performed using a Hummingbird Scientific liquid-electrochemistry TEM holder.
Here, we present operando cross-platform sXAS/TEM methods to study the electrochemical studies of Mg-metal in Mg(BH4)-based electrolytes to gain insights into the role of anode/electrolyte interface and interphase during Mg deposition and stripping processes. We use extended X-ray absorption fine structure (EXAFS) to investigate the solvent coordination of the as-prepared Mg(BH4)2: 3LiBH4/DME electrolyte and after one reduction/oxidation cycle. The decrease in the intensity of Mg-O bond after the first cycle suggested the loss in solvent coordination at the interphase. Upon studying the oxidation/reduction processes in liquid TEM, we observe the formation of passivating surface SEI layer and H2 gas beneath the magnesium metal deposit. Further study of B K-edge XAS indicated that [BH4]- anion promoted the reductive formation of H2 gas, and the reduction of Mg2+. These results present a new paradigm into using magnesium borohydride-based electrolytes for rechargeable magnesium batteries.
5:00 PM - EN06.04.07
High-Power Alternative-Ion Batteries via Co-Intercalation
Jennifer Donohue1,2,Kathleen Moyer2,Adam Cohn2,Cary Pint2
State University of New York at Binghamton1,Vanderbilt University2Show Abstract
A critical bottleneck in the development of a high power battery material is to overcome the rate-limiting de-solvation step associated with intercalation of an alkali ion into graphite. Here, I will discuss results focused on utilizing co-intercalation as a method to enable fast charging and high power batteries. This concept pivots on the strong interaction between linear ether solvent molecules and alkali metal ions that results in a solvent shell which chelates the metal ion. This strong interaction leads the ion to maintain its solvent shell through insertion and extraction from graphite, bypassing the normal rate-limiting kinetics associated with desolvation. I will specifically discuss high-rate potassium and sodium co-intercalation into natural graphite that exhibits specific capacities above 100 mAhg-1 at currents of 5 Ag-1. To pair this into a full-cell battery architecture, I will discuss cathode options including Prussian blue nanoparticles that exhibit similar capacities at rates up to 10 C. The results from this work demonstrates how cointercalation of alkali ions poses an exciting option for high power batteries that rely on strategies where moderate energy density and low-cost make them an excellent option for emerging areas of grid storage, electric vehicles, and other high-power applications.
5:00 PM - EN06.04.08
Modification of LiFePO4 Cathode with 3D "Silk flowers" Like Ni-Al-Li-LDHs in Lithium-Ion Battery
Xiaoqing Zhang1,Jiayuan Shi1,Yong Xiang1
University of Electronic Science and Technology of China1Show Abstract
Nano layered double hydroxides Ni-Al-Li-LDHs was firstly introduced into Lithium-ion battery to modify LiFePO4 (LFP) cathode. The 3D "Silk flower" like Ni-Al-Li-LDHs were in-situ grown on the surface of LFP by hydrothermal method with specific mole ratios of LFP/LDHs. A series of structural characterization have been carried out on these composites. The XRD, SEM, FT-IR and TEM test results reveal that Ni-Al-Li-LDHs was truly grown on the surface of LFP and formed a core-shell like structure. Then these LFP/LDHs composite were taken as cathode materials in lithium battery. Their electrochemical performance were detected by electrochemical impedance spectroscopy (EIS), cyclic voltammetry(CV), galvanostatic charge-dischage cycling. Both electrochemical activity and stability of LFP have obtained significant progress by Ni-Al-Li-LDHs optimizing. The highest specific capacity was obtained by LDHs/LFP (mole ratio 1:4) as 180 mAhg-1, which is much higher than that of pure LFP cathode (120 mAhg-1) . Moreover, the stability of these composites cathode were also outstanding by 200 cycling evaluation. The excellent performances of LFP/LDHs cathode in lithium ion battery were due to the enhancement of lithium ion mobility by Ni-Al-Li-LDHs. Which based on the unique layered by layered structure and ion exchangeable ability of Ni-Al-Li-LDHs. Besides, LDHs also enlarge the specific surface area of LFP by N2 adsorption-desorption experiment. Which have provided more active site for electrochemical reaction. Modifying LFP by Ni-Al-Li-LDHs was a novelty attempt and achieved some positive results.
5:00 PM - EN06.04.09
The Effect of Calendering Temperature for Sulfur Electrodes Used for Large-Scale Lithium-Ion Batteries
Rachel Ye1,Jeffrey Bell1,Daisy Patino1,Mihri Ozkan1,Cengiz Ozkan1
University of California, Riverside1Show Abstract
Current commercial lithium-ion batteries have reached their capacity limit due to the materials in use. To improve the capacity of lithium-ion batteries, researchers have started to use new electrode materials such as sulfur and silicon. Sulfur, although being a high capacity cathode material, suffers from conductivity and expansion problems. To increase the conductivity of sulfur electrodes, a high percentage of carbon is usually added to the electrode, resulting in low sulfur loading. A common method to improve the conductivity and the sulfur loading of an electrode is to calendar or densify the electrode, resulting in a more intimate contact between active material and the conductive additive. Herein we look at the positive effects of calendaring sulfur electrodes at different temperatures, varying from room temperature to as high as 120C. By elevating the electrode temperature, the heat softens the sulfur, allowing the sulfur particles to better come into contact with the conductive network and improving the conductive network. The increase in calendar temperature increases cycle life, capacity, and rate capability of the lithium-sulfur battery.
5:00 PM - EN06.04.10
Characterization and Electrochemical Analysis of a Novel Alkoxide-Based Electrolyte for Mg-Ion Batteries
Anushka Dasgupta1,Jake Herb1,Craig Arnold1
Princeton University1Show Abstract
Multivalent batteries, such as rechargeable Mg-ion batteries, may be able to overcome the safety and cost limitations of Li-ion batteries. They are promising candidates for applications in large-scale stationary energy storage as well as in transportation. Finding high-voltage electrolytes which are compatible with the Mg-ion battery chemistry continues to be a research focus. In this work, we present electrochemical analysis of a a fluorinated dialkoxide-based magnesium-ion electrolyte. The electrolyte is stable at high voltages (>2V) and shows good performance in full battery cells using Chevrel phase Mo6S8. Its performance in other sulfide-based cathodes is also reported.
5:00 PM - EN06.04.12
A New Design Concept of Li-S Battery Based on the Reaction Mechanism of Sulfur for High Performance Energy Storage Systems
Jin Kyeong Kang1,Ji Hoon Kang1,Ju Kyoung Kang1,Yongju Jung1
The Lithium-Sulfur (Li-S) batteries have been extensively investigated for next energy storage applications due to its great advantages such as much higher energy density and lower cost than current Lithium-ion batteries. Li-S batteries still suffer from several key performance issues (e.g., poor cycle life, self-discharge and rate capability) associated with polysulfide shuttling effect and slow kinetics. To tackle these problems, various approaches including the C-S nanocomposite and the interlayer concept have been suggested. For C-S composites, the structural parameters of the carbon hosts (i.e., pore size and porosity) proved to be very crucial to Li-S battery performance. In addition, a porous carbon interlayer inserted between the cathode and the separator to confine soluble polysulfides has been found effective in mitigating the polysulfide shuttling phenomena. However, most of approaches might not be suitable for mass production of cheap Li-S batteries. In this study, we propose a novel design of Li-S battery integrating a protective cathode incorporating a porous polysulfide adsorbent and a functional separator, which can be applied to current process and facilities. We focused on mitigating the polysulfide loss and further improving practical energy density of Li-S battery by investigating the electrochemical behavior of Li-S batteries under high sulfur loading conditions.
5:00 PM - EN06.04.13
A Highly Robust Sulfur Cathode with a Structure Stabilizer for a Long-Life Li-S Battery
Jong Won Park1,Ji Hoon Kang1,Jin Kyeong Kang1,Euishin Yoon1,Yongju Jung1
Lithium-sulfur (Li-S) batteries have received considerable attention owing to their unique features such as high capacity, non-toxicity and natural abundance. Despite recent significant performance improvement, several key performance issues (e.g., cycle life, rate property, self-discharge, safety) still remain unsolved. Recently, many researchers have focused on the development of new cathode materials along with the carbon-sulfur (C-S) concept to tackle poor cycle life and rate problems of Li-S batteries. A huge number of porous carbon materials have been applied to the sulfur cathode until now. Mostly, C-S composites have been found very effective in improving cycle performance. However, their practical application would be considered very hard since the synthesis process is so complex and expensive.
In this study, we present a highly sustainable sulfur cathode which can maintain its structural integrity and minimize polysulfide diffusion out of the cathode during cycling. Integration of inorganic porous materials within a sulfur cathode would be highly helpful for confining soluble polysulfides. We demonstrate enhancement of structural stability of sulfur cathode by incorporating porous inorganic materials and suggest a rational design of sulfur cathode ensuring long cycle life and high sulfur loading.
5:00 PM - EN06.04.14
Inverse Vulcanization with Functional Linkers—Towards New Cathode Active Materials
Haneol Kang1,Moon Jeong Park1
Lithium ion batteries have penetrated into our daily lives ranging from mobile phones to electric vehicles. This prompted considerable efforts toward the development of high-energy density lithium batteries, with a focus on designing new electrode active materials. In this context, elemental sulfur has been regarded as one of the promising candidates for next generation cathode materials owing to their high theoretical specific capacity (1672 mAh/g) and high energy density (2567 Wh/kg）based on 2-electron redox chemistry. In addition, low-cost, low-toxicity, and natural abundance of sulfur are another advantages. In spite of aforementioned strengths, sulfur cathodes suffer from critical limitations to be used in practical applications, such as volumetric changes during cycling, irreversible relocation of charge/discharge products, intrinsic insulating nature of sulfur, and dissolution of lithium polysulfide intermediates into the polar electrolyte. In the present study, we report the development of new sulfur cathodes based on inverse-vulcanized polymers. A new strategy is the use of functional linkers for the vulcanization process to enhance the electrochemical properties upon modulating electronic structures of the resultant polymers. Inverse-vulcanized polymers with 2,3,5,6-Tetra(allyloxy)benzoquinone linker showed amorphous morphology with improved redox activity, low band gap, and enhanced electric conductivity. By taking advantages of these benefits, the lithium-sulfur batteries can deliver high reversible discharge capacity of 1100 mAh/g with good capacity retention and decent rate capability up to 10 C.
5:00 PM - EN06.04.15
Highly Stable 3D Nanoporous SnSb Alloy as an Lithium Storage Material
Sangjin Choi1,Yoon Yun Lee1,Dana Jin1,Hyesoo Kim1,Wooyoung Shim1
Yonsei University1Show Abstract
Lithium ion battery (LIB) with high energy and power densities are actively investigated to enhance the competitiveness and extensive development of electric vehicles (EVs) and energy storage system (ESS), and for facilitating novel portable devices. The energy density of a battery is primarily determined by the charge-discharge capacities of the electrode materials and the operating potential of the battery. Due to the low theoretical capacity of graphite (372 mAhg-1 for LiC6), the commercialized anode material for LIBs, development of alternative anode materials for LIBs is strongly required for future applications. Certain metals and metalloids that alloy with lithium is particularly promising, such as Sn and Sb which both show several times higher energy densities than that of graphite (e.g. 993 mAhg-1 for Li4.4Sn; 660 mAhg-1 for Li3Sb). The choice of the SnSb from several synergistic effects between the Sn and Sb: 1) both components of alloy distribute to its high theoretical capacity of 824 mAhg-1; 2) alloying/dealloying of Sn and Sb occur at different potentials, which smoothens the mechanical stress.
SnSb + xLi+ + xe- ↔ LixSnSb (0≤x≤1.6)
Li1.6SnSb + 1.4Li+ + 1.4e- ↔ Li3Sb + Sn
Sn + 4.4Li+ + 4.4e- ↔ Li4.4Sn
In the present work, nanoporous SnSb alloy with 3-D pore system and well-developed crystalline framework was successfully obtained via nano-casting method by using a 3-D porous silica as a hard-template. The nanoporous SnSb exhibits high specific surface area of 115 m2g-1, large pore volume of 0.5 cm3g-1 and dual nanopore sizes of 4 and 22 nm. Thus, 3-D nanoporous SnSb showed outstanding rate capabilities up to 2 C as well as high reversible lithium storage capacity of 810 mAhg-1 with excellent coulombic efficiency of 99.3 %.
5:00 PM - EN06.04.16
Synthesis and Electrochemical Performance of Sn-Fe Alloy with High and Stable Capacity as Anodes in Lithium-Ion Batteries
Fengxia Xin1,Hui Zhou1,Dongsheng Ji1,Xiaoya Wang1,Yong Shi1,Jia Ding1,Fredrick Omenya1,Natasha A. Chernova1,M. Stanley Whittingham1
Binghamton University1Show Abstract
Sn-based alloy materials have gained popularity to replace commercial graphite anodes due to their higher gravimetric and volumetric capacity for next generation rechargeable lithium-ion batteries. Here a series of SnxFe alloys with nanosized derived from chemical transformation of pre-formed Sn nanoparticles as templates were successfully prepared. The morphology, crystal structure and composition of SnxFe intermetallic are greatly influenced by temperature, surface stabilizer and reagent molar ratio. The optimized Sn-Fe anode with core-shell structure could deliver 541 mAh/g after 200 cycles at the C/2 rate, corresponding to nearly 100 % initial capacity and 90.2% of the maximum charging capacity. The calculated volumetric capacity was about two times than that of commercial carbon. It also has excellent rate performance, delivering 94.8%, 84.3%, 72.1%, and 58.2% of the 0.1C capacity (679.8 mAh/g) at 0.2C, 0.5C, 1C and 2C, respectively. When it went back from 1 C to 0.1 C, the charge capacity recovered to 513.3, 603.2, 662 and 692.8 mAh g−1. The exploring of Fe-Sn alloy from this work also provides insight for the designing other Sn-M (Co, Ni, Cu, Mn etc.) system.
Acknowledgement: This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under Award No. DE-EE0006852.
5:00 PM - EN06.04.17
Inert Gas Annealing of Li4Ti5O12 Targeting Improvement of Conductivity
Joe Sakai1,Ilham Bezza1,Cécile Autret1,David Duveau1,Francois Tran-Van1,Fouad Ghamouss1
Univ of Tours1Show Abstract
Li4Ti5O12 (LTO) is regarded as the most promising oxide negative electrode material for lithium ion batteries (LIB), with excellent charge-discharge cyclability and a flat plateau in potential-charge properties. However, the insulating nature of LTO hinders high-speed charge-discharge processes. Generally, the strategies to improve the conductance of a material include the enhancement of the conductivity by doping, and the mixing with a conducting material. The approach for the commercial oxide active materials is to use a carbon-based conductor, whereas studies on substitution of the tetravalent (4+) Ti ions with trivalent (3+) or pentavalent (5+) metal ions are ongoing in the laboratory level.
In the present study, we attempted to introduce oxygen deficiency to LTO thick films, expecting partial valence change of Ti ions. Amorphous LTO films that were deposited by an electrostatic spray deposition method in air at 250°C were post-annealed at 700°C in various ambient gases. A film annealed in Ar still showed sharp charge and discharge peaks in its current-potential properties, suggesting the possibility of reduction in an inert gas without the collapse of its crystal structure. Coating an LTO thick film with a glass-like carbon ultrathin layer, that also requires a post-treatment in the inert ambient gas, has been also attempted. Comparison of these films in conductivity is presented.
5:00 PM - EN06.04.18
Effects of Porous Media Selection in Lithium Iron Phosphate Cathodes
Alfredo Martinez-Morales1,Jeffrey Geiger1
University of California, Riverside1Show Abstract
Engineering higher-performing lithium-ion batteries may be key to meeting the ever-growing demand for energy storage. Commonly used in battery cathodes because of its high theoretical capacity, thermal stability, and ecological friendliness, lithium iron phosphate (LFP) still has one major flaw, its low conductivity, both electronic and ionic. Technology is limited by this property of LFP, but several methods have been developed to increase battery performance, such as carbon additives and controlled porosity. Previous studies have established the importance that these two factors play in battery performance, and this project investigates the relationship between performance and pore size.
In lieu of a more common carbon black/graphite additive, graphene was chosen in this research due to its higher surface area and electronic conductivity. Additionally, four polymers (polyethylene terephthalate, polyvinyl chloride, polystyrene, and polypropylene) were tested as porous media, all with different particle surface-area-to-volume ratios, allowing us to manipulate pore surface area while keeping porosity (%) constant. Cathode slurries were mixed with LFP as the active material and with varying polyvinylidene difluoride (PVDF) to graphene weight ratios in an N-methylpyrrolidone (NMP) solvent. Then, the mixtures were spread on non-conducting plates, dried, and their electronic conductivities were measured using a four-point probe.
The PVDF/Graphene ratio yielding the highest conductivity was determined, and then slurries were prepared with the added polymers in order to achieve porosities between 20% and 40%. The slurries were spread onto non-conducting plates, dried, and calcinated. The four-point probe method was used to determine each sample’s conductivity, and coin cell batteries were assembled. Lastly, an Arbin battery tester was used to perform cycling tests on each of the prepared batteries. Imaging of each cathode material was also taken using a scanning electron microscope (SEM), and the crystallinity of the material was analyzed by dispersive spectroscopy (EDS).
5:00 PM - EN06.04.19
Scalable Synthesis of High Capacity and High Cyclability Polyethylene Terephthalate (PET)–Derived Graphite Anode for Lithium-Ion Battery
Taner Zerrin1,Arash Mirjalili1,Rachel Ye1,Zafer Mutlu1,Cengiz Ozkan1,Mihri Ozkan1
University of California, Riverside1Show Abstract
Synthetic graphite is still the standard anode material for lithium ion battery industry. Herein, we introduce a scalable, recycled Polyethylene Terephthalate (PET)–derived graphite anode for lithium-ion battery. PET-derived anodes were obtained through electrospinning process. Formation of graphite tubes with diameter of 0.5 – 2 micrometers was confirmed through Raman analysis and Scanning Electron Microscopy (SEM) images respectively. Additionally, X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Brunauer-Emmett-Teller (BET) analysis were applied as well. Electrochemical properties of PET-derived graphite anodes were tested through Galvanostatic Cycling with Potential Limitation (GCPL), Galvanostatic Intermittent Titration Technique (GITT), Electrochemical Impedance Spectroscopy (EIS) and Constant Voltage (CV). Obtained PET-derived carbons show high surface area with good lithium diffusivity and capacity of 264 mAh/g after 500 cycles. The study provides a novel pathway to fabricate high capacity energy storage device from recycled waste plastic.
5:00 PM - EN06.04.20
Thermal Stability Analysis of Lithium-Sulfur Batteries via Controlled Conditioning Techniques
Daisy Patino1,Jeffrey Bell1,Rachel Ye1,Cengiz Ozkan1,Mihri Ozkan1
University of California, Riverside1Show Abstract
The market for electric vehicles (EVs) has gained significant popularity over recent years. However, in order for that market to continue to expand relative to consumer demands, lithium ion technologies need to be improved to withstand the common stresses encountered in EV applications. An example of such stresses is unanticipated fluctuations in internal and ambient temperatures. Currently, optimal performance of lithium ion batteries is limited to a specific operating temperature, subsequently, batteries that are exposed to temperatures outside of the operating range will exhibit detrimental performance effects such as a loss in capacity, life cycle degradation, and more concerning safety hazards. These effects are attributed to the decomposition of the solid electrolyte interphase (SEI) layer during stressed cycling. The common approach towards improving robustness of SEI is to utilize various electrolyte additives. This approach, however, is prone to adverse effects such as rapid self-discharge and a decrease in energy density. Herein, we propose a noninvasive approach towards developing robust SEI layer in lithium sulfur batteries to improve thermal stability at high temperatures. Robustness of SEI layers is modified via controlled conditioning of lithium sulfur (LiS) batteries within specified voltage regions. This work explores conditioning of LiS batteries at low temperatures within 8 – 17 degrees Celsius in attempt to slow down the kinetics involved in SEI formation and hence, develop robust SEI layers within the first cycles. The batteries are then evaluated for aging at elevated temperatures within 30 - 60 degrees Celsius, and assessed via GCPL, CV, EIS, and GITT.
5:00 PM - EN06.04.21
An Analysis of Lithium Sulfur Interactions via GITT Measurements
Daisy Patino1,Rachel Ye1,Jeffrey Bell1,Mihri Ozkan1,Cengiz Ozkan1
University of California, Riverside1Show Abstract
The galvanostatic intermittent titration technique (GITT) is an electroanalytical tool commonly used in lithium ion technologies which uses transient and steady state measurements to obtain kinetic and thermodynamic properties of electrodes materials. The GITT procedure involves applying short current pulses followed by relaxation periods. In conventional lithium ion cells, when we apply current pulses, we induce concentration changes within the host electrodes. In lithium sulfur batteries however, the concentration change occurs in the electrolyte due to the reduction process of sulfur to electrolyte-soluble polysulfides. Hence, it is a complex procedure to quantify values such as, chemical diffusivity coefficient of lithium ions and the resistivity through the electrolyte in lithium sulfur cells, as opposed to conventional solid state lithium ion cells. Accordingly, research efforts to utilize GITT for lithium sulfur cells, omit the polysulfide shuttle mechanism to obtain a semi-solid state model. Herein, we explore a complete lithium sulfur model that enables more accurate quantitative depictions for mass transport rates, chemical reaction rates, and sulfur utilization.
5:00 PM - EN06.04.22
The Effects of Electrode Density on Sulfur and Silicon Performance for Lithium-Ion Batteries
Jeffrey Bell1,Rachel Ye1,Daisy Patino1,Leon Peng1,Andrew Scott1,Cengiz Ozkan1,Mihri Ozkan1
University of California, Riverside1Show Abstract
Electrochemical storage has gained momentum amid increasing concerns for a cleaner, more environmentally friendly future. Currently, lithium ion battery systems do not meet the requirements to quell the increasing concerns and it is therefore imperative to move in a new direction. Top contenders for ‘beyond lithium’ is lithium-sulfur (Li-S) and silicon (Si). In order to scale up these new materials, it is crucial to study the effects of densification on their performance. Densification may alter the robustness of the electrode’s conductive network and ability of the electrolyte to penetrate the electrode. Through altering the electrode's density, it possible to improve network conductivity while also maintaining electrolyte penetration. Silicon and Sulfur electrodes were set to different densities and then characterized using gravimetric cycling, galvanostatic intermittent titration technique, cyclic voltammetry, and material utilization.Herein we report the fabrication of simple sulfur and silicon electrodes at different densities and their long term positive effects on cycling, rate performance and capacity.
5:00 PM - EN06.04.23
Electrochemical Analysis of Bismuth Nanotubes and WS2 Electrode Materials Imbedded in Flexible Perchlorate-Based Polymer Gel Electrolyte for Use in Mg-Ion Battery Cells
Todd Houghton1,Hongbin Yu1
Arizona State University1Show Abstract
Over the past two decades, lithium ion battery chemistries have enabled the practical development of many new products and technologies. Today, rechargeable Li-ion batteries are often the primary means of providing electrical power to a diverse and growing number of devices, from mobile phones to electric vehicles. Despite many advances and widespread adoption, Li-ion battery technologies have limitations. Battery chemistries based on lithium ions have a high theoretical gravimetric capacity of 3829mAh/cm3 only a modest volumetric capacity of 2044mAh/cm3 . Volumetric capacity is anticipated to be especially important in IoT devices and wearables, where thin, flexible batteries which can cover large areas are ideal. By comparison, divalent batteries based on zinc or magnesium ions have theoretical volumetric capacities of 5854mAh/cm3 and 3882mAh/cm3 respectively . In addition to somewhat a somewhat modest volumetric capacity, lithium is far less common in the earth’s crust than magnesium or zinc and possesses higher reactivity . Because of this, lithium-ion batteries are anticipated to be less environmentally friendly and cost effective than divalent metal-ion batteries for applications requiring many large battery cells. It should also be noted that over the past year, the safety of lithium-ion batteries in consumer products has been called into question after a high-profile recall involving lithium-ion batteries in smartphones.
One means of addressing the shortcomings of lithium ion-battery technologies is to develop new battery chemistries based on divalent metal ions such as magnesium. Divalent metal-ion batteries could be made of flexible materials that allow for safe operation in the event of mechanical damage. Here we present an experimental magnesium ion half-cell constructed from flexible materials. A magnesium-ion cell was chosen due to its low material cost, good theoretical volumetric capacity, simple fabrication steps, and separator-free reaction chemistry. Flexible, insertion-type anodes and cathodes were fabricated using bismuth nanotubes and tungsten disulfide respectively. A polymer-based electrolyte made of PVDF-HFP and magnesium perchlorate was chosen for its demonstrated high ionic conductivity and mechanical flexibility. Each interface of the half-cell was characterized though the use of cyclic voltammetry and Raman spectroscopy, while a complete cell was examined using a commercial battery tester. Cell fabrication, component/interface electrochemistry, electrode materials, and overall cell performance will be described in detail.
 R.K. Guduru, J.C. Icaza. “A Brief Review on Multivalent Intercalation Batteries with Aqueous Electrolytes”. Nanomaterials, vol. 6, pp. 1-19, Feb 2016
 N. Nitta, F. Wu, J.T. Lee, and Gleb Yushin. “Li-ion battery materials: present and future”. Materials Today, vol. 18, pp. 252-264, June. 2015
5:00 PM - EN06.04.24
Improving Performance of LFP Cathodes by Optimizing Porosity
Jiyong Kim1,Alfredo Martinez-Morales1
University of California, Riverside1Show Abstract
Lithium iron phosphate (LiFePO4, LFP) is the driving technology for battery energy storage applications due to its high theoretical capacity (170 mAh g-1), cost-effectiveness, long cycle life, good thermal stability, and environmental friendliness in comparison to other traditional cathode materials such as lithium cobalt oxide (LiCoO2) and lithium manganese oxide (LiMn2O4). However, key limitations of LFP are a low intrinsic electronic conductivity (~10-9 S cm-1) as well as limited ionic conductivity at room temperature. Several methods have been used to enhance electronic conductivity, such as carbon coating, super-valence ion doping on the Li-site, and nano-networking of electronic conductive metal-rich phosphides. On the other hand, enhancement of ionic conductivity has been researched to a less extend.
Theoretically, Chen et al. determined that the best conductivity for LFP cathode is achieved by a combination of 30% active material, 7.5% graphite, 10.15% carbon black, and 12.35% polyvinylidene fluoride (PVDF) by volume, to achieve a 40% porosity. In this work, we used polyvinyl chloride (PVC) and Polystyrene (PS) powders to experimentally optimize the size of pores and control the porosity of prepared cathodes. LFP cathodes are prepared in a slurry composed of lithium iron phosphate powder as the active material, carbon black and graphite as conductive additives, PVDF as a binder, and N-methyl-2-pyrrolidone (NMP) as the solvent. To create a matrix of pores, the cathodes are heated at 300°C and 360°C to evaporate PVC and PS, respectively. To calculate pore volume of the cathodes, their morphology is characterized by a scanning electron microscope (SEM) an image processing. To determine battery performance, coin-cells were assembled with cathodes containing various percentage of porosity. Cycling testing was performed using an Arbin tester.
5:00 PM - EN06.04.25
Sodium Storage in Rippled Bilayer Graphene—A Model for Amorphous Carbon Anodes
Weiyi Zhang2,Woochul Shin1,Clement Bommier3,Xiulei Ji1,Alex Greaney2
Oregon State University1,University of California, Riverside2,Princeton University3Show Abstract
Amorphous carbons such as hard carbon are being developed as anode materials for next generation sodium ion batteries. These materials have a structure composed of nanoscale domains of twisted, rumpled, and vertically disordered graphene stacks. Compared to graphite anodes, the dilated morphology makes insertion of large sodium ions into the galleries between graphene layers more energetically favourable. However, there is a disparity between the average gallery spacing observed experimentally during Na intercalation and the ab initio predicted local dilation necessary for favourable intercalation. In this work sinusoidally rippled bilayer graphene is used as a model for amorphous hard carbon. Using this it is demonstrated that the rippled graphene morphology creates local regions with large d-spacing, and in these geometrically dilated regions Na storage is highly favorable.
5:00 PM - EN06.04.26
Synthesis of LiFePO4 in a Limited Air Environment—Synthesis Time Study and Optimization
Fei Gu1,2,Kichang Jung1,2,Alfredo Martinez-Morales1,2
University of California, Riverside1,Winston Chung Global Energy Center, University of California, Riverside2Show Abstract
LiFePO4 has been proved as a promising cathode material for LIBs because of its cost effective, high thermal stability, environmental friendly, and theoretical capacity of 170 mAh/g. Previously our group demonstrated that LiFePO4 is able to be synthesized in a limited air environment. By doing this, it lowers the requirement of equipment, gas environment, and decrease the synthesis time needed in compare to traditional solid state method. And by applying a closed crucible designed to limit the amount of oxygen participating in the reaction, the quality of produced materials was improved and so decrease the cost of LiFePO4 synthesis. However, the oxidation of the LiFePO4 is still an issue that limit the quality of synthesis. In order to further improve the quality of the LiFePO4, a time study on the synthesis is conducted. In our method, pre-dried iron phosphate (FePO4) and lithium acetate (CH3COOLi) are mixed. The mixture is placed in a sealed crucible and heated in a muffle furnace. The crucible is inserted in to the furnace after it reaches the designed temperature and removed from the furnace once designed heating time is reached to limit the byproduct reaction. Multiple experimental runs are conducted with various heating time to optimize the time needed for the reaction. The time study allows toward the understanding of the reaction evolution, especially the type of the oxide formed during the reaction and the oxidation development base on time. Several techniques are applied to characterize the properties of synthesized LiFePO4. The crystal structure and chemical composition of the synthesized material are characterized by X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). The grain size of resulted materials is determined by scanning electron microscopy (SEM). Raman spectroscopy is applied to detect the type of oxidization and oxidization level inside the materials. The synthesized LiFePO4 is assembled into a half coin cell for electrochemical characterization. The cycleability and electrochemical performance of the cells under different C-rates are tested using an Arbin tester.
5:00 PM - EN06.04.27
Scalable Silicon-Carbon Nanospheres Electrodes for Lithium-Ion Batteries
Jingjing Liu1,Changling Li1,Bo Dong1,Daisy Patino1,Zafer Mutlu1,Mihri Ozkan1,Cengiz Ozkan1
University of California, Riverside1Show Abstract
Silicon is considered as one of promising electrode materials for lithium-ion batteries (LIBs), thanks to its high energy density, high theoretical specific capacity and low discharge potential. Note that the strong volume expansion (~300%) of silicon during lithiation and delithiation is one of the main issues for its applications. To solve this issue, we develop silicon-carbon nanospheres (SCNSs) as LIB anodes by a simple and scalable method. Firstly, silicon nanospheres (SNSs) are synthesized via magnesium reduction of silica nanospheres, which are produced by an in-situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS). The SNSs with 3D nanoporous spheres have an average diameter of ~100 nm. To fully extract the real performance of the SNSs, carbon coating is further performed to enhance the electronic conductivity of SNSs. We obtain the SCNSs LIB anodes exhibiting excellent lithium storage performance, which have a reversible capacity of ~3170 mAh g−1, high rate capability (C/2) and cyclic stability (capacity of ~1010 mAh g-1 after 500 cycles). Our results demonstrate that the spherical nature and high nanoporosity of the SCNSs significantly improves the electrochemical stability by accommodating the volume changing.
5:00 PM - EN06.04.28
Stability and Electrochemical Performance of Different LiVOPO4 Phases
Marc Francis Hidalgo1,Fredrick Omenya1,Natasha A. Chernova1,M. Stanley Whittingham1,Yuhchieh Lin2,Shyue Ping Ong2
Binghamton University1,University of California, San Diego2Show Abstract
VOPO4 is a promising cathode material in Li-ion batteries due to its ability to hold multiple Li-ions per redox center. Specifically, the V5+/V4+ and V4+/V3+ redox couples allow for the insertion of two Li-ions into VOPO4, LiVOPO4 and Li2VOPO4. These phases also exhibit polymorphism, with VOPO4 and LiVOPO4 having seven and three different polymorphic phases, respectively. A thorough comparison of the physical and electrochemical properties of these polymorphs will help determine the mechanisms by which these phases form and how they perform electrochemically. This study focuses on the three most promising LiVOPO4 phases: α1 (layered, tetragonal), β (orthorhombic), and ε (triclinic). All phases are synthesized from a single precursor, LiVOPO4-2H2O, reducing the effects of synthesis methods on the physical and electrochemical properties of the products, allowing for more accurate comparisons. The transformations between the different phases are studied using x-ray diffraction and differential scanning calorimetry. The electrochemical performance of each phase is evaluated using galvanostatic discharge-charge between 1.5 to 4.5 V at various current rates. The lithium diffusion coefficients are calculated using cyclic voltammetry and galvanostatic intermittent titration technique.
5:00 PM - EN06.04.29
A First-Principles Investigation of Lithium Intercalation and Diffusion in Titanium Dioxide with Oxygen Vacancy
Hsiu-Liang Yeh1,Shih-Hsuan Tai1,Chieh-Ming Hsieh1,Bor Kae Chang1
National Central University1Show Abstract
Titanium dioxide has recently attracted focus as a potential anode material in lithium-ion rechargeable batteries (LiBs) because of the low cost, abundant source, light weight, safety, and high theoretical capacity. However, the practical application of TiO2 is restricted by its poor electronic conductivity and inefficient lithium diffusion. Previous experimental studies have demonstrated that the incorporation of oxygen vacancy into TiO2 nanostructures as a strategy to enhance anode material performances. In this work, three most common polymorphs of TiO2 were investigated for potential as lithium-ion battery anode materials: anatase, rutile and TiO2(B). Each phase was modeled and first-principles study based on density functional theory (DFT) calculations were employed to investigate the intercalation and diffusion behavior of lithium at dilute concentrations in TiO2 with/without an oxygen vacancy. Total energies of possible intercalation sites were first calculated to determine favorable sites among the three phases. Furthermore, all lithium diffusion pathways form one stable site to another were examined by climbing image nudged elastic band method. To understand the effect of oxygen vacancy on the lithium diffusion mechanism, energy barriers of lithium diffusion for pristine and oxygen-defective TiO2 structures were calculated and compared. In addition, the electronic structures of TiO2 with oxygen vacancy were compared to pristine TiO2. The results indicate that among the three polymorphs, TiO2(B) may the better choice for use as anode material after oxygen vacancy creation because of lower diffusion energy barrier change and larger band gap reduction.
Shyue Ping Ong, University of California, San Diego
Byoungwoo Kang, POSTECH
Jeff Sakamoto, University of Michigan
Kang Xu, U.S. Army Research Laboratory
Army Research Office
EN06.05: Solid Electrolytes
Wednesday AM, April 04, 2018
PCC North, 100 Level, Room 121 B
8:00 AM - EN06.05.01
Synthesis, Air Stability and Applications of Li7La3Zr2O12
Huanan Duan1,Biyi Xu1,Wenhao Xia1
Shanghai Jiao Tong University1Show Abstract
In recent years, cubic lithium garnets, Li7La3Zr2O12 (LLZO) in particular, have attracted much attention due to reasonable ionic conductivity (>10-4 S cm-1 at room temperature), good chemical stability with lithium metal, and near-to-unit transference number. It has been reported that small amount of Al2O3 dopant can act as sinter aid to yield dense and cubic phase, the fast Li-ion conducting phase. This talk first introduces our efforts to synthesize such lithium garnets. We investigated the effect of preparation parameters including Al2O3 doping amount, crucibles, and heating schedule on the materials properties such as ionic conductivity and air stability, using various characterization techniques such as XRD, ICP-OES, SEM-EDS, NMR, Raman and EIS. We optimized the preparation process and obtained lithium garnets with good air stability and room-temperature conductivity in the range of 4~6 x 10-4 S cm-1 . Then the reaction mechanisms of LLZO in ambient air are discussed [2,3,4]. This talk ends with the applications of LLZO in novel lithium batteries such as solid lithium batteries, hybrid lithium battery and Li-S batteries [5,6].
 Biyi Xu, Huanan Duan, Wenhao Xia, Yiping Guo, Hongmei Kang, Hua Li, Hezhou Liu, Journal of Power Sources, 302 (2016) 291-297.
 Wenhao Xia, Biyi Xu, Huanan Duan, Yiping Guo, Hongmei Kang, Hua Li, Hezhou Liu, ACS Appl. Mater. & Interfaces, 8 (2016) 5335-5342.
 Wenhao Xia, Biyi Xu, Huanan Duan, Xiaoyi Tang, Yiping Guo, Hongmei Kang, Hua Li, Hezhou Liu, Journal of the American Ceramic Society (2017) 1-8.
 Huanan Duan, Hongpeng Zheng, Ying Zhou, Biyi Xu, Hezhou Liu, accepted by Solid State Ionics.
 Biyi Xu, Wenlong Li, Huanan Duan, Haojing Wang, Yiping, Guo, Hua Li, Hezhou Liu, Journal of Power Sources 354 (2017) 68-73.
 Biyi Xu, Huanan Duan, Hezhou Liu, Chang-An Wang, Shengwen Zhong, ACS Applied Materials & Interfaces 9 (2017) 21077-21082.
8:30 AM - EN06.05.02
Structures and Properties of Cathode Materials of Li-Ion Batteries
Tongchao Liu1,Feng Pan1
Peking University1Show Abstract
Insight into relationship between Crystal/Interface structure and properties of capacity, stability and rate capability are important for developing advanced Li-ion batteries. Using theoretical calculations combined with experimental in-situ tests, we did extensive studies on the kinetic of Li-ion diffusion for two representative cathode materials: layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) and LiFePO4. We not only focus on the bulk kinetics, but also the kinetics across electrode/electrolyte solid-liquid interface and in the electrolytes. For example, we first proposed that "Janus" solid-liquid interface would facilitate the Li-ion transport in battery and introducing some disordering in non-active cathode materials would activate them for Li-ion storage. Finally, we also developed some in-situ technologies for battery studies. For example, using electrochemical quartz crystal microbalance (EQCM), we achieve an in situ experimental investigation of the LiFePO4 (LFP) and NaFePO4 (NFP)/electrolyte interfacial kinetics for Li(Na)-batteries. （Ref. 1）
For high energy and power density applications (e.g., EVs), the safety becomes especially important. Using ab initio calculations combined with experiments, we clarified how the thermal stability of NMC materials can be tuned by the most unstable oxygen, which is determined by the local coordination structure unit (LCSU) of oxygen (TM(Ni, Mn, Co)3-O-Li3-x’): each O atom bonds with three of transition metal (TM) from the TM-layer and three to zero of Li from fully discharged to charged states from the Li-layer. Under this model, how the lithium content, valence states of Ni, contents of Ni, Mn, and Co, and Ni/Li disorder to tune the thermal stability of NMC materials by affecting the sites, content, and the release temperature of the most unstable oxygen is proposed. (Ref. 2)
(a)F. Pan el al., “Kinetics Tuning of Li-ion Diffusion in Layered Li(NixMnyCoz)O2”, J. Am. Chem. Soc., 2015, 137, 8364; (b) Adv. Energy Mater., 2015, 1501309(1-9).(c) Nano Lett,2015, 15 (9), pp 6102 (d) Adv. Energy Mater., (Front page ) 2016, 1601894 (e)F. Pan el al., Excess Li-ion storage on reconstructed surfaces of nanocrystals to boost battery performance, Nano Lett, 2017, 17, 6018−6026, (f) Nano Energy 2017 37, 90 (g) Nano Lett., 2017, 17 (8), 4934–4940, (h) Inorg. Chem. 2017 DOI: 10.1021/acs.inorgchem.7b02150
(a) F. Pan el al., “Tuning of Thermal Stability in Layered Li(NixMnyCoz)O2”, J. Am. Chem. Soc., 2016, 138 (40), 13326, (b) Nano Letters 2016, 16 (10), pp 6357; (c) Nano Letters, 2015, 15, 5590; （d） J. Phys. Chem. Lett., 2017, 8 (22), 5537–5542
9:00 AM - EN06.05.03
A Stable 3 V All-Solid-State Sodium–Ion Battery Based on a Closo-Borate Electrolyte
Corsin Battaglia1,Leo Duchene1,Ruben-Simon Kühnel1,Evelyn Stilp1,Eduardo Cuervo Reyes1,Arndt Remhof1,Hans Hagemann2
Empa-Swiss Federal Laboratories for Materials Science and Technology1,University of Geneva2Show Abstract
We report on a particularly stable 3 V all-solid-state sodium–ion battery built using a closo-borate based electrolyte, namely Na2(B12H12)0.5(B10H10)0.5. The battery employs a sodium metal anode and a NaCrO2 cathode. Battery performance is enhanced through the creation of an intimate cathode–electrolyte interface resulting in reversible and stable cycling with a capacity of 85 mAh/g at C/20 and 80 mAh/g at C/5 with more than 90% capacity retention after 20 cycles at C/20 and 85% after 250 cycles at C/5. We also discuss the effect of cycling outside the electrochemical stability window and show that electrolyte decomposition leads to faster though not critical capacity fading. Our results demonstrate that owing to their high stability and conductivity closo-borate based electrolytes could play a significant role in the development of a competitive all-solid-state sodium–ion battery technology.
 L. Duchêne, R.-S. Kühnel, E. Stilp, E. Cuervo Reyes, A. Remhof, H. Hagemann, C. Battaglia, Energy & Environmental Science 10, 2609 (2017)
10:00 AM - EN06.05.04
Computational Investigation on Oxide Electrolytes with Garnet Structure and Conduction-Pathway-Blocking Dopants
Randy Jalem1,2,Ryosuke Natsume3,Masanobu Nakayama2,3,4
Japan Science and Technology Agency (JST), PRESTO1,National Institute for Materials Science – Global Research Center for Environment and Energy based on Nanomaterials Science (NIMS-GREEN)2,Nagoya Institute of Technology3,Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University4Show Abstract
Driven by the promise of high safety and reliability for all-solid Li ion battery applications, many research efforts have since been performed for developing oxide-type solid electrolytes with a garnet framework. This is made evident by the large number of research works found in the literature, particularly on ionic conductivity optimization by way of doping at the cation sub-lattice of the garnet crystal structure. Some of these doping strategies result to direct blockage of the Li ion conduction pathway and could cause profound impacts on the structure and overall conductivity behavior of the material. To elucidate what these impacts exactly are, we carried out atomistic-level computational modelling on two specific doping or cation incorporation in the Li sub-lattice of the garnet structure: i) Ga doping1 which has been reported to reach 10-3 S/cm order of Li ionic conductivity (among the highest reported so far for garnet compounds2) and ii) proton exchange which occurs upon exposure to air or moisture during synthesis or powder handling.
1. Jalem et al., Chem. Mater. 2015, 27, 2821−2831.
2. Bernuy-Lopez et al., Chem. Mater. 2014, 26, 3610−3617.
EN06.06: Li-Sulfur Batteries
Y. Shirley Meng
Wednesday AM, April 04, 2018
PCC North, 100 Level, Room 121 B
10:15 AM - EN06.06.01
All- Solid Lithium- Sulfur Batteries
Toyota Research Inst1Show Abstract
To meet the future demands of future hybrid, plug-in hybrid, and all electric vehicles, advances in energy storage for transportation is indispensable. Additionally, energy diversification is vital to tailor electrification requirements to optimize the cost, range and size of the application. Recently, post Li-ion batteries, such as Li-O2, multivalent and anion batteries, have garnered much attention. The lithium metal sulfur (Li-S) battery is an exciting system due to its high theoretical capacity (1673 mAh/g-S) and the potential of low cost.1 However, realizing Li-S batteries relies on solving key challenges such as dissolution and shuttling of polysulfides, low sulfur utilization at high-areal loading levels, lithium metal dendrite formation, and continuous electrolyte decomposition on the Li metal surface.
The potential benefits of solid-state electrolytes, such as polymer electrolytes, gel electrolytes and ion-conducting ceramics electrolytes, are wide-operating windows, active material dissolution prevention and metal dendrite inhibition. However, low ionic conductivity and interfacial stability require continued development to achieve a viable energy storage system. Recently, ionic conductivities rivaling liquid based-systems have been observed for the sulfide-based, glass-ceramic L10GeP2S12 (LGPS),2 encouraging continued research into solid-state batteries using sulfide-based solid-electrolytes. Tatsumisago et al.3 illustrated and impressive initial cycling results using lithium-indium alloy anode, a lithium iodide/lithium sulfide solid-solution cathode, and a solid sulfide electrolyte: over 1000 mAh/g at 2C cycling for over 2000 cycles. Inspired by the results, developing all solid Li-S batteries presents hope for a high-energy density battery.
Here, we will present the electrochemical discharge mechanism of solid state Li-S batteries using glass-ceramic, sulfide-based solid-electrolyte and a lithium metal anode. The solid-state reactions of the active materials with the solid-electrolyte are evidenced through X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and thermal analysis. Our results reveal that the electrochemical properties are closely tied to the fabrication of the solid-state cathodes. Additionally, researchers have recently observed the decomposition of sulfide electrolytes in contact with lithium metal4,5. We will discuss protection strategies to inhibit undesired reactions at the anode-electrolyte interface as potential solutions to further improve all-solid Li-S batteries for vehicle electrification.
 Manthiram, A. et al. Chem. Rev. 2014, 114, 11751-11787.
 Kanno, R. et al. Nat. Mater. 2011, 10, 682-686.
 Tatsumisago, M. et al. Adv. Sustainable Syst. 2017, 1700017, 1-6.
 Sakamoto, J. et al. Electrochimica Acta 2017, 237, 144-151.
 Janek et al. Solid-State Ionics 2016, 286, 24-33.
10:45 AM - EN06.06.02
High Energy Density Lithium/Sulfur Batteries for NASA and DoD Applications
Ratnakumar Bugga2,J.P. Jones1,Simon Jones1,Jasmina Pasalic1,Charlie Krause1,M. Hendrickson2,E.J. Plichta2
Jet Propulsion Laboratory1,U.S. Army RDECOM CERDEC2Show Abstract
By virtue of their high specific energy, energy density and long cycle life, lithium-ion batteries have contributed to a significant enhancement or even enablement of several space missions and defense applications. However, NASA’s future missions, e.g., Astronaut’s Portable Life Support System (PLSS) for Extra-Vehicular Activities (EVA), small planetary rovers, planetary probes, CubeSats etc., require battery technologies with higher specific energies and energy densities, for short cyclic lifetimes. Similarly, Department of Defense (DoD) is interested in the development of a high energy rechargeable battery system for soldier and navy applications. The lithium/sulfur system is deemed the most viable future technology, because of its high theoretical specific energy (3-4x vs Li-ion). However, despite several years of development, this system hasn’t matured yet, mainly due to the challenges from the soluble polysulfides, which results in a ‘redox shuttle’ and a deposition of lithium sulfides and impedance growth at the lithium anode. Several attempts were reported in the literature with novel cathode designs, e.g., hierarchical porous carbon structures to sequester sulfur and its reduction products, and also with electrolyte solutions to minimize their solubility. 1-3 Good cycle life was achieved in some of these cases, but the sulfur loadings in the cathodes are much lower (1-2 mg/cm2) than desired. To realize high specific energy from a Li/S cell, sulfur loading will need to be high, i.e., > 12 mg/cm2 per side or >6 mAh/cm2 areal capacity. Recently, our group4 and several others6-8 have been developing new sulfur composite cathodes blended with transition metal sulfides (e.g., titanium and molybdenum disulfide), which assist in the trapping of polysulfides within the cathode and improve the cycle life of Li-S cells. In addition, we have demonstrated similar improvements in the cycle life with the use of ceramic-coated separators, e.g., Tonen separators coated with alumina and aluminum fluoride,8 and with protected Li anodes. In this paper, we will describe our recent studies with the high-areal-capacity composite sulfur cathodes, coated separators and protected Li anodes for improved cyclic stability of our laboratory Li-S cells.
11:15 AM - EN06.06.03
An Alternative to Prelithiation for Full Cells Utilizing Sulfur Cathodes
Rachel Ye1,Jeffrey Bell1,Daisy Patino1,Kazi Ahmed1,Mihri Ozkan1,Cengiz Ozkan1
University of California, Riverside1Show Abstract
Lithium-ion batteries are crucial to the future of energy storage. However, the energy density of current lithium-ion batteries is insufficient for future applications. Sulfur cathodes have garnered a lot of attention in the field due to their high capacity potential. Although recent developments in sulfur cathodes show exciting results in half-cell formats, there has been minimal progress in utilizing sulfur cathodes in full cells. This is because current lithium-ion cathodes are expected to act as the lithium source in a lithium full-cell, and sulfur cathode cannot do so. Current methods for incorporating lithium in full cells utilizing sulfur cathodes involves prelithiating the anode or using lithium sulfide, the lithiated form of sulfur. These methods, however, complicate material processing and creates safety hazards. Herein, we present a novel full-cell battery architecture that bypasses the issues associated with current methods. This battery architecture gradually integrates controlled amounts of pure lithium into the system by allowing lithium the access to the external circuit. A high specific energy density of 350 Wh/kg after 250 cycles at C/10 was achieved in a sulfur-silicon full cell using this method. This work should pave the way for future researchers into sulfur full cells.
EN06.07: High-Energy Cathodes
Wednesday PM, April 04, 2018
PCC North, 100 Level, Room 121 B
1:30 PM - EN06.07.01
From Cation Redox to Anion Redox Electrochemistry
Y. Shirley Meng1,2,Minghao Zhang1,Thomas Wynn1
University of California, San Diego1,Sustainable Power and Energy Center2Show Abstract
This work provides novel insights into the oxygen activity and its correlation with the chemical environment of transition metals at the surfaces , sub-surfaces and bulk of layered transition metal oxides in lithium ion and sodium ion batteries. The oxygen activity in battery materials are historically challenging to be analyzed due to the lack of proper techniques that can simultaneously probe the unoccupied oxygen 2p and transition metal 3d orbitals. The energy range of soft X-ray covers both the oxygen K-edge and transition metal L-edges, the combination of which can provide precise information on the local transition metal-oxygen (TM-O) octahedral crystal field. We take advantage of unique features of soft X-ray absorption spectroscopy (s-XAS) and electron energy loss spectroscopy (EELS) to investigate the differences in the oxygen activity between the classical layered oxides and Li rich layered oxides and the impact of such difference on the surrounding TM-O environment, during the first cycle and after a number of high voltage cycles. The experimental data will be carefully interpreted with the help of first principles computation. With a quantitative comparison between the classical layered oxides and lithium rich layered oxides, we hope to provide a strategy to effectively control the oxygen activities in layered oxides, especially when guest ion (Li+ and Na+) concentrations are low (high voltage range). Last but not least, we will demonstrate the important role of defects in anion redox active materials.
2:00 PM - EN06.07.02
Materials Design of High-Energy Cation/Anion Redox in Li-Rich Cathode Materials—Li5FeO4, Li4Mn2O5 and Li2MO3
Northwestern University1Show Abstract
The energy density of many lithium metal oxide battery cathodes is limited by redox reactions associated with the transition metal alone. Anionic redox reactions are affording new opportunities to increase this energy density. Here, we present results from first-principles density functional theory (DFT) calculations aimed at understanding the combined cation/anion redox of Li-rich materials, and designing new materials that will enable high-capacity, reversible cycling with minimal oxygen evolution. We illustrate this approach on three Li-rich compounds: Li5FeO4, Li4Mn2O5, and Li2MnO3.
Li5FeO4: Initial removal of Li is accompanied by Fe migration to form a disordered rocksalt structure. A local Li6-O coordination of oxygen, identified by DFT calculations, raises the O 2p band and enables reversible O-/O2- redox behavior, previously unknown in this material. This insight leads to the prediction and subsequent experimental demonstration of anionic and cationic redox reactions with good reversibility and without any obvious O2 gas release.
Li4Mn2O5: We study the recently-reported, high-capacity, disordered rocksalt-type Li4Mn2O5 compound and also determine the ground state ordered structure of Li4Mn2O5 via a DFT-based enumeration method. DFT calculations show that the delithiation process occurs via a three-step reaction pathway involving the complex interplay of cation and anion redox reactions: i) Mn3+→ Mn4+ (LixMn2O5, 4 > x > 2), ii) O2− →O1− (2 > x > 1), and iii) Mn4+ →Mn5+ (1 > x > 0) concomitant with Mn migration from the original octahedral site to the adjacent tetrahedral site. Finally, we predict that alloying with M = V and Cr in Li4(Mn,M)2O5 would produce new stable compounds with substantially improved electrochemical properties.
Li2MO3: We catalog the family of Li2MO3 compounds as active cathodes or inactive stabilizing agents using high-throughput density functional theory (HT-DFT). With an exhaustive search based on design rules that include phase stability, cell potential, resistance to oxygen evolution, and metal migration, we predict a number of new Li2MIO3–Li2MIIO3 active/inactive electrode pairs, in which MI and MII are transition- or post-transition metal ions, that can be tested experimentally for high-energy-density lithium-ion batteries.
3:30 PM - EN06.07.03
Towards High Energy Na-Ion Batteries
Pacific Northwest National Laboratory1Show Abstract
Na-ion battery is an emergent technology beyond Li-ion chemistries with very attractive properties for grid scale energy storage. However, the limited energy density comparing to Li-ion batteries has been a major argument against its wide applications. One of the main reasons is from the cathode material, which usually has limited specific capacity and low charge cut-off voltage. Here, we introduce our recent work on the development of high energy density Na-ion battery cathodes and the fundamental understanding behind that. In particular, a cathode material synthesized showed >180 mAh/g specific capacity between 2-4.2V and very good cycling stability. The corresponding energy density of the cathode is ~600 Wh/kg. Good air stability was also demonstrated. It is a big leap for the field making Na-ion battery potentially promising as competitive to Li-ion batteries.
4:00 PM - EN06.07.04
Obstacles Toward Unity Efficiency of LiNi1-2xCoxMnxO2 (x=0~1/3) (NCM) Cathode Materials—Insights from Ab Initio Calculations
Chaoping Liang1,2,Fantai Kong2,Roberto C. Longo2,Chenxi Zhang2,Yifan Nie2,Yongping Zheng2,Kyeongjae Cho2
State Key Laboratory of Powder Metallurgy, Central South University1,The University of Texas at Dallas2Show Abstract
Achieving the energy limit of LiNi1-2xCoxMnxO2 (NCM) (x=0~1/3) cathodes has raised great research interests in recent years. In order to obtain longer cycle and calendar life, current NCM cathodes deliver far less than their theoretical energy density, even after intense modifications such as cation/anion doping, coating, core-shell structure, and concentration-gradient design. By a throughout and careful literature survey, we summarized five individual phenomena observed at the end of charge: O3-O1 phase reaction, crack propagation, Li-Ni exchange, layered-spinel phase transition, and Oxygen evolution. These five phenomena have been reported independently by different researchers using novel ex situ and in situ characteristic techniques, and which one leads to the degradation of NCM cathode is not clear.
In this study, we perform a comprehensive study of LiNi1-2xCoxMnxO2 (NCM) (x=0~1/3) cathodes, using first-principle calculations within the DFT+U framework and a bond model based on the effective interaction of transition metal (TM) ions. Based on our results, we have located the obstacles toward unity efficiency and revealed that the degradation strongly depends on the Ni concentration and the depth of charge (DOC). Based on our findings, the optimal composition for a good electrochemical performance of NCM cathode materials is found within the region of 1/10<x<1/4 (50-80% of Ni). We also proposed separate solutions for each Ni concentration to prevent degradation at high voltage/capacity. For 1/4≤x≤1/3, a feasible way to reduce the Oxygen evolution during charge would be through doping with high valence TM ions, in order to reduce strongly covalent Co-O bonds. On the other hand, for 0≤x≤1/4, the use of coating materials or novel materials design like core-shell and concentration-gradient structures could restrict the lattice distortion along the charge process. The key factors found in present work will help researchers, especially the newcomers to understand the obstacles toward unity efficiency, and also help them to rationally design NCM cathode materials with high-energy density through possible solution mechanisms, such as doping, coating or novel nanostructures, like core-shell or concentration gradient cathodes.
C. P. Liang, Roberto C. Longo, et al. Obstacles toward unity efficiency of LiNi1-2xCoxMnxO2 (x=0~1/3) (NCM) cathode materials: Insights from ab initio calculations. Journal of Power Sources, 2017, 340: 217-228.
C. P. Liang, F.T. Kong, et al. Unraveling the Origin of Instability in Ni-Rich LiNi1−2xCoxMnxO2 (NCM) Cathode Materials. The Journal of Physical Chemistry C, 2016, 120 (12): 6383–6393.
C. P. Liang, F.T. Kong, et al. Site Dependent Multicomponent Doping Strategy for Ni–rich LiNi1–2yCoyMnyO2 (y = 1/12) Cathode Materials for Li–Ion Batteries. In revision.
C. P. Liang, Roberto C. Longo, et al. Ab initio study on Surface Segregation and Anisotropy of Ni-rich LiNi1-2xCoxMnxO2 (NCM) (x ≤ 0.1) Cathodes. Submitted.
4:15 PM - EN06.07.05
Atomic Thermal Migration Studies on Layered Cathode Materials for Li-Ion Batteries by Using In Situ High Temperature Neutron Diffraction and Gas Analyses
Hyungsub Kim1,Seongsu Lee1
Korea Atomic Energy Research Institute (KAERI)1Show Abstract
To cope with global warming and ever-increasing energy demands, there has been a great effort to develop an efficient energy storage system (ESS) for electric vehicles (EVs) and grid-scale ESSs. Li-ion batteries (LIBs) have the greatest potential to be used such applications on their high energy and power densities, however, as the size of battery packs is getting larger, there is a growing concern on the battery safety issues.[1-2] Battery safety is closely related to the thermal stability of the cathode materials because the structural transition or decomposition of charged cathode generally involves O2 evolution, which increase the risk of thermal explosion of battery packs.[3-4] In this regards, in-situ monitoring the structural evolution of cathode materials at various conditions (i.e. temperature, state of charge, C-rates, etc.) is a critical issue to develop safer electrode materials.
Neutron diffraction techniques have been widely used to investigate the crystal structure of electrode materials for rechargeable batteries on the merit of the direct interaction of neutron with atomic nucleus, which enable us to investigate detailed structure of electrode materials containing light elements such as Li, Na and O. Furthermore, quantitative discussion on neighborhood elements in the periodic table such as Mn, Fe, Co, and Ni are comparably easy, which is difficult with X-ray. For this reason, neutron diffraction researches on electrode materials for rechargeable batteries have been significantly increased for several years.
In this presentation, we will demonstrate the effect of transition metal ions in Ni-Co-Mn-based oxide (NCM) electrode materials upon phase transition at high temperature using combined in-situ high temperature neutron diffraction and gas analyses. We believe that this research can provide a new insight into atomic migration and phase evolution in NCM materials and intuition for the design of cathode materials with high thermal stability.
 J. Zheng, T. Liu, Z. Hu, Y. Wei, X. Song, Y. Ren, W. Wang, M. Rao, Y. Lin, Z. Chen, J. Lu, C. Wang, K. Amine, F. Pan, J. Am. Chem. Soc. 2016, 138, 13326-13334.
 D. Larcher, J. M. Tarascon, Nat. Chem. 2015, 7, 19.
 K.-W. Nam, S.-M. Bak, E. Hu, X. Yu, Y. Zhou, X. Wang, L. Wu, Y. Zhu, K.-Y. Chung, X.-Q. Yang, Adv. Funct. Mater. 2013, 23, 1047.
 S.-M. Bak, K.-W. Nam, W. Chang, X. Yu, E. Hu, S. Hwang, E. A. Stach, K.-B. Kim, K. Y. Chung, X.-Q. Yang, Chem. Mater. 2013, 25, 337.
 C. P. Grey, J. M. Tarascon, Nat. Mater. 2017, 16, 45.
 A. M. Balagurov, I. A. Bobrikov, N. Y. Samoylova, O. A. Drozhzhin, E. V. Antipov, Russ. Chem. Rev. 2014, 83, 1120.
4:30 PM - EN06.07.06
Electrophoretic Deposition as a Manufacturing Strategy for High Areal Capacity Cathodes
Kathleen Moyer1,Rachel Carter2,Keith Share1,Trevor Hanken1,Landon Oakes3,Cary Pint1
Vanderbilt University1,U.S. Naval Research Laboratory2,PPG Paints3Show Abstract
Electrophoretic deposition (EPD) is a technique widely used for high throughput industrial processes. Here we show EPD as a route to manufacture low-cost, high areal capacity battery electrodes. Using non-toxic, quick-drying acetone as a solvent, we use EPD to fabricate lithium iron phosphate cathodes with high areal loadings of 50 mg/cm2. Higher electrode mass loadings substantially contribute to increasing the energy density while minimizing the overall cost of the battery materials by decreasing the ratio of inactive to active components. This work highlights the electrochemical performance of high areal loading EPD manufactured electrodes with capacities up to ~8 mAh/cm2. EPD is a promising technique to manufacture the next generation of nanoarchitecture electrodes with high energy density at reduced manufacturing costs.
4:45 PM - EN06.07.07
Synthesis and Characterization of Li Excess Mo-Based Cathodes for Li-Ion Batteries
Ethan Self1,Gabriel Veith1,Rose Ruther1,Jagjit Nanda1
Oak Ridge National Laboratory1Show Abstract
Development of low-cost cathodes with high energy density and long cycle life is critical to enable advanced Li-ion batteries for transportation applications. Traditional layered LiMO2 (M = Mn, Co, Ni, etc.) cathodes cannot reversibly cycle their entire Li supply (e.g., x ≤ 0.5 in Li1-xCoO2). When charged beyond ~4.3 V vs. Li/Li+, many lithium-transition metal oxides undergo irreversible structural changes with concomitant oxygen gas evolution, resulting in irreversible capacity loss and voltage fade during cycling.[1-3] Understanding and addressing these structural instabilities is necessary to design new cathode materials which can better utilize their Li supply without sacrificing cycle life.
Li2MoO3 has recently received attention as a cathode material due to the unique properties of Mo which can access several oxidation states (e.g., Mo4+ in Li2MoO3 and Mo6+ in MoO3), allowing for the possibility to store multiple Li per transition metal. Our previous work showed that Li2MoO3 also has excellent oxidative stability and thus may be useful to stabilize the oxygen sublattice of conventional cathode materials. This presentation will detail the synthesis and characterization of layered-layered composite Mo-based cathodes with the general formula xLi2MoO3-(1-x)LiMO2 (M = Ni, Mn, and/or Co). Various synthesis routes including solid-state reactions and sol-gel chemistry will be explored to understand the effect of synthesis conditions on the structure and electrochemical properties of these materials. The structural evolution of these cathodes over several charge/discharge cycles will be studied using Raman spectroscopy and X-ray diffraction (XRD). In-situ mass spectrometry will be used to monitor the composition and quantity of gas evolved during battery operation. The effect of fluorine doping on the operating potential and oxidative stability of these materials will also be discussed.
Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.
 R. E. Ruther, H. Zhou, C. Dhital, K. Saravanan, A. K. Kercher, G. Chen, A. Huq, F. M. Delnick, J. Nanda, Chem. Mater. 2015, 27, 6746-6754.
 M. Sathiya, G. Rousse, K. Ramesha, C. P. Laisa, H. Vezin, M. T. Sougrati, M. L. Doublet, D. Foix, D. Gonbeau, W. Walker, A. S. Prakash, M. Ben Hassine, L. Dupont, J. M. Tarascon, Nat Mater 2013, 12, 827-835.
 R. E. Ruther, A. S. Pandian, P. Yan, J. N. Weker, C. Wang, J. Nanda, Chem. Mater. 2017, 29, 2997-3005.
Shyue Ping Ong, University of California, San Diego
Byoungwoo Kang, POSTECH
Jeff Sakamoto, University of Michigan
Kang Xu, U.S. Army Research Laboratory
Army Research Office
Thursday AM, April 05, 2018
PCC North, 100 Level, Room 121 B
8:00 AM - EN06.08.01
Photo-Patternable Lithium-Ion Electrolytes
Bruce Dunn1,David Ashby1,Christopher Choi1
University of California, Los Angeles1Show Abstract
Although photo-patterning has been used extensively in the semiconductor industry for the fabrication of low cost structures, it has hardly been utilized in the battery community. The photo-patterning of solid electrolytes offers several potential advantages as the ability to achieve spatial control with micron and sub-micron resolution enables one to form electrolytes in non-planar geometries as well as to develop new battery fabrication routes, especially ones that offer better integration with microelectronics and on-chip batteries. The present paper describes our work in photo-patterning two different lithium-ion conducting electrolytes, silica-based ionogels and an epoxy-based gel electrolyte.
Ionogels are pseudo-solid-state electrolytes in which an ionic liquid electrolyte confined in a mesoporous inorganic matrix leads to a material that possesses the electrochemical properties of the ionic liquid despite being a macroscopic solid. In the work reported here, we used UV cross-linking to induce hydrolysis and condensation of a sol-gel silica network. The resulting materials retained the ion transport and electrochemical stability of the confined ionic liquid electrolyte and demonstrated photolithographic patterning of simple structures. The photoresist used in this study, SU-8, was modified with LiClO4 to form a gel electrolyte. The presence of the lithium salt reduces the degree of cross-linking during UV exposure, leading to increased conductivity but without sacrificing photo-patterning properties. The material also exhibits good thermal and electrochemical stability, excellent mechanical integrity and micron-scale patterning. Thin films of both UV cross-linked electrolytes were evaluated in electrochemical half cells and exhibited good interfacial stability.
8:30 AM - EN06.08.02
Diagnosis of All-Solid-State Batteries Using Three-Electrode Cells
Yoon Seok Jung1,Young Jin Nam1,Kern Ho Park1,Dae Yang Oh1
Ulsan National Institute of Science and Technology (UNIST)1Show Abstract
The safety concerns originating from the use of flammable organic liquid electrolytes have impeded widespread of conventional Li-ion batteries for the large-scale energy storage applications such as battery-driven electric vehicles and energy storage systems. In this regard, solidifying electrolytes with inorganic superionic conductors is considered as an ideal solution. Among various inorganic solid electrolyte (SE) candidates, sulfide materials are suitable to achieve high performance for all-solid-state batteries as the conductivities for the-state-of-the-art sulfide materials (e.g., Li9.54Si1.74P1.44S11.7Cl0.3: 25 mS cm-1) are comparable to that for liquid electrolytes and the sulfide materials are soft. The softness of sulfide materials allows surface contacts with active materials by simple pressing procedure at room temperature, avoiding deteriorating high-temperature sintering process which is the critical limitation for oxide SE materials.
Despite the extensive progresses in the SE materials, the test protocols for all-solid-state batteries are poorly developed. In most previous literatures, the performances of working electrodes for all-solid-state batteries have been assessed by using In or Li-In as reference and counter electrodes without any verification. Moreover, analysis of all-solid-state full-cells, which is crucial for practical applications, has been unprecedented so far. In this regard, development of all-solid-state three-electrode cells is of prime importance. Unfortunately, the unique fabrication protocol of all-solid-state batteries make the development of all-solid-state three-electrode cells extremely challenging.
In this presentation, our recent results on development of the first all-solid-state three-electrode cells and its application to diagnoses on failure modes of several battery systems.
 Y. S. Jung, D. Y. Oh, Y. J. Nam, K. H. Park, Israel J. Chem. 55 (2015) 472-485.
9:00 AM - EN06.08.03
Multiscale Thermomechanical Model to Predict Thermal Runaway in Lithium-Ion Batteries
Abhishek Sarkar1,Abhijit Chandra1,Pranav Shrotriya1
Iowa State University1Show Abstract
In the advent of fast charging and high voltage storage devices, thermal runaway followed by meltdown of lithium ion battery is a cause of concern. Prior experiments on lithium battery modules have shown issues of high thermal generation in high energy storage electrodes. Theoretical and numerical analysis have focused on either the factors causing heat generation from electrode particles at microscale or the possible thermal management techniques to mitigate thermal failure in fullscale battery. We report a multiscale thermomechanical model which bridges heat generation by the electrode particle to thermal runaway in a multilayered electrode separator system. The thermal analysis is coupled with an elasto-plastic diffusion induced stress model to compare the thermal and mechanical performance under different design and operating parameters. A parametric analysis is performed for combination between three cathode and anode materials and the performance of the model is studied over a range of particle radius and charging rates. Higher charging rate and larger particle size are found to push the electrode into plastic deformation. Four modes of heat generation are considered including three conventional heating modes, i.e. polarization heating due to surface over-potential, entropic heating due to entropy release during lithiation, resistive heating due to electrical resistivity of the electrodes; and heat generation from the plastic deformation of electrode particles under faster charging condition. The results present a conflicting scenario where reducing the particle size diminishes the stress field but increases the volumetric heat generation, and vice-versa. The paper concludes with a set of optimum design parameters and limiting charging rate for different electrode material combinations in a battery and proposes thermal management techniques to permit faster charging of the battery.
9:15 AM - EN06.08.04
High Volumetric and Areal Capacity 3D-Structured Electroplated Tin Electrode
Pengcheng Sun1,Paul Braun1
University of Illinois at Urbana-Champaign1Show Abstract
Here we show a two-step electrodeposition process to fabricate a high volumetric and areal capacity 3D-structured Sn/C anode starting from a commercial mesostructured thick 3D Ni scaffold. An anode with 20% Sn loading exhibits a volumetric/areal capacity of ∼879 mAh/cm3 and 6.59 mAh/cm2 after 100 cycles at 0.5C and a good half-cell rate performance of about 750mAh/cm3 and 5.5 mAh/cm2 (charge) at 10C. The 3D Sn/C anodes also show good compatibility with commercial LCO cathodes. EIS and finite element simulation are applied to verify the effects of Sn loading and carbon coating on the cycling and power performance of the 3D Sn/C anodes. We find that while higher loadings of Sn will cause a larger capacity decay with cycling, the addition of the carbon coating significantly improves the structural stability of the 3D-structured anodes. The combination of the high volumetric and areal capacity these anodes provide may make them of interest for next generation energy storage systems.
9:30 AM - EN06.08.05
High Rate and Stable Cycling of High Energy Cathode LiVOPO4 with Nanosizing, Carbon Coating and Structure Reconstruction by a Mechanical-Thermal Method
Yong Shi1,Hui Zhou1,Fredrick Omenya1,Natasha A. Chernova2,M. Stanley Whittingham1,2
Binghamton University1,NECCES, Binghamton University2Show Abstract
The market for lithium ion batteries (LIBs) has been rapidly grown with exponentially increasing demands for electric vehicles and portable information technology devices. However, the current materials are still limited in capacity and energy density. A feature common to the current materials is that less than one electron participates in the redox reaction. To increase the chemical energy stored, a multielectron redox reaction would be preferred. Recently, researchers have reported LiVOPO4 as a promising multi-electron material to incorporate two electrons. There are two redox couples in this material, V3+/V4+ and V4+/V5+, per vanadium, which enables two Li ions to be reversibly inserted/extracted, leading to a high theoretical capacity of 305 mAh g-1 based on the weight of Li2VOPO4. However, LiVOPO4 has both poor lithium diffusivity and electronic conductivity, which can cause polarization and poor utilization of active material. To overcome these challenges, we propose a mechanical method to nanosize LiVOPO4 and coat carbon on the surface of particles meanwhile, which shortens diffusion pathway for Li ions and increases the electronic conductivity. Whereas the structural disorder and poor crystallinity were detected in LiVOPO4 after the mechanical treatment, which impeded the migration of Li ions in the diffusion passages and resulted a poor cycling stability. A following thermal method was adopted to reconstruct the structure of LiVOPO4 under a controlled condition with keeping particles nanosizing and without reducing LiVOPO4. The resulting LiVOPO4 gave superior electrochemical performance in terms of rate capability and cycling stability, with the highest stable cycling capacity, 260 mAh g-1 at C/5, of any two electrons redox phosphate system reported to date.
This research is funded by (1) U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under BMR Award No. DE-EE0006852, and (2) NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0012583.
9:45 AM - EN06.08.06
Design and Synthesis of a Novel High Energy Density Li2MnxCo1-xSiO4 Cathode Material
Xianhui Zhang1,Zhenlian Chen1,Liyuan Huai1,Deyu Wang1,Jun Li1
Ninbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences1Show Abstract
The development of novel high-capacity and high-energy cathode materials for lithium ion batteries is a focus of the energy storage technology. Different from LiMO2 and LiFePO4, which only one Li+ can be reversibly cycled, Li2CoSiO4 would allow reversible extraction of two Li+ in principle thus delivering a higher theoretical capacity of 325 mAh/g. Moreover, it has been proved to show a high voltage plateau above 4.0 V, which makes it among the few candidates having theoretical energy density above 1200 Wh/kg.
However, poor electronic conductivity seriously hinders its electrochemical performance. Unfortunately, carbon-coating, which has significantly enhanced the electronic transportation of many polyoxyanion materials, is usually fruitless and frustrating in Co-silicates. In the past decade, the reversible capacity of Li2CoSiO4 has been staying 75 mAh/g above 3.0 V or 107 mAh/g above 1.5 V despite extensive efforts.
To break the development bottleneck of Co-silicates, first-principles calculations had been performed by our group to investigate the changes of lattice and electronic structure for understanding electrochemistry of Li2CoSiO4. With the guidance of theoretical calculations, we had evaluated several mechanisms that may control the electronic structures of Co-silicates in doping. At the same time, a series of innovations in material synthesis were also carried out to improve the conductivity of the materials. Under such a joint effort, a P-doped Li2CoSiO4, whose discharge capacity up to 144 mAh/g above 2.5 V, was successfully synthesized for the first time in 2016. Recently, we develop a novel Mn-doped Li2CoSiO4 with more advance performance. This new scheme not only reduces the proportion of Co, thus enhancing the cost competitiveness, but also improves the electrochemical performance effectively, resulting in a more highly leveraged possibility for the application of cobalt based silicates as high energy cathode materials. The synthesized Li2MnxCo1-xSiO4/C could deliver a reversible capacity up to 208 mAh/g in the voltage window of 1.5-4.8 V, which is almost double of the highest record in the last ten years. Moreover, we are surprising to find that the Mn involves in the redox reaction during charging and discharging. This is in contrast to that of the LiNixCoyMn1-x-yO2 and Mn-silicates. The introduction of Mn may bring a synergistic effect with Co redox, leading to the significant increase in reversible capacity.
In summary, with the joint theoretical and experimental studies, we design and synthesis a capacity record-breaking Li2MnxCo1-xSiO4 and for the first time realize a reversible capacity above 200 mAh/g for Co-silicates. This on the one hand opens a new window for the further research of silicate material, on the other paves an avenue to a new prototype of advanced high energy cathode materials from tetrahedral groups.
EN06.09: Anodes I
Thursday AM, April 05, 2018
PCC North, 100 Level, Room 121 B
10:30 AM - EN06.09.01
Effect of Surface Modification on Surface Chemistry and Electrochemistry of Silicon-Based Anode Materials
National Renewable Energy Laboratory1Show Abstract
The demands of sustainable high-energy-density rechargeable batteries have led to the exploration of high-capacity and low-cost electrode materials. Based on reversible alloying-dealloying reactions, silicon stores 10 times more lithium (Li22Si5, 4,200 mAh g-1; Li15Si4, 3,579 mAh g-1, 8,343 Ah L-1) than the current commercial graphite anode (LiC6, 372 mAh g-1, 804 Ah/L). However, unlike the topotactic intercalation of Li into carbonaceous materials, the alloying/dealloying reaction causes much more dramatic, three-dimensional chemical and structural rearrangements on the surface and bulk structure, and results in a fast degradation in cycling performance. Moreover, the formation of solid electrolyte interphases on the Si surface results in the loss of lithium inventory and low Coulombic efficiency. Besides of using sophisticated design of nanostructure silicon materials and electrodes, our research has concentrated on surface modification strategies to stabilize the surface of the reactive silicon materials, but also accommodate the volumetric changes during lithaition/delithiation of silicon materials. The effects of the surface modification have been investigated through morphology, structure, mechanical and electrochemical characterization and analysis methods. The research has elucidated the important role of surface modification in stabilizing the cycling performance and enable a high level of material utilization at high mass loading. This talk will focus on reviewing the surface modification approaches used for improving electrochemical performance, and elaborate the effects of surface modification on the surface chemistry and electrochemistry of silicon-based anodes, and also discuss the strategies towards developing practical silicon-based anodes for high-energy-density lithium-ion batteries.
11:00 AM - EN06.09.02
Quantify the Irreversible Structural and Chemical Changes in Nanostructured Si and SiO Electrodes
Yue Qi1,Kwang Jin Kim1
Michigan State University1Show Abstract
Understanding the battery degradation requires identifying the “irreversible” chemical and structural changes – from atomic to meso-scale – that appear during battery cycling. To design nanostructures mitigating these degradation mechanisms, will further rely on our ability to quantify and predict these irreversible changes. This talk will focus on recent modeling methodology developed to compliment in situ observations in order to elucidate the underlying factors contributing to mechanistic failures. For example, most experimental techniques are not sufficiently sensitive to reveal the amorphous Si and SiO characteristics change upon cycling. Reactive molecular dynamics, along with a new lithiation and delithation algorithm, simultaneously tracks and correlates the lithiation-delithiation rate, compositional change, mechanical property evolution, stress distributions, and fracture. Thus the model can quantify the irreversible volume change of Si and SiO nanostructures, the amount of trapped Li, the generation and distribution of inner pores and coating delamination, and the atomistic structural difference in the amorphous structures, upon cycling. These findings lead to design criteria for mechanically stable coated Si nanostructures and battery operating guidelines to mitigate capacity loss due to trapped Li and coating delamination.
11:30 AM - EN06.09.03
Stable Three-Dimensional Composite Lithium Metal Anode with Electrolyte-Proof Architecture for High-Energy and High-Power Applications
Dingchang Lin1,Yi Cui1
Stanford University1Show Abstract
Rechargeable batteries based on lithium (Li) metal chemistry are attractive for next-generation energy storage. Nevertheless, dendritic growth, infinite relative dimension change, severe side reactions and limited power output, greatly impede their practical applications. The presented work for the first time introduces an electrolyte-proof design of three-dimensional Li metal anode where most of the Li domains are embedded in a Li-ion conductive matrix. In the new architecture, the Li-ion conductive matrix isolate the embedded Li domains from liquid electrolyte and thus prevent severe initial side reactions, while the matrix can simultaneously transport Li-ion and maintain the electrochemical activity of the embedded Li. This composite electrode was obtained by reacting over-stoichiometry of Li with SiO above Li melting temperature. The unique reaction dynamics results in a structure of Li embedded in the LixSi-Li2O matrix with one-pot synthesis. Since uniform Li nucleation and deposition can be fulfilled owing to the high-density active Li domains, the as-obtained nanocomposite electrode exhibits low polarization, stable cycling and high-power output (up to 10 mA/cm2) even in carbonate electrolytes. The Li-S prototype cells further exhibited highly improved capacity retention under power-intersive operation (~600 mAh/g at 6.69 mA/cm2). The all-round improvement on electrochemical performance sheds light on the effectiveness of the new design principle for developing safe and stable Li metal anodes with high-power capability.
11:45 AM - EN06.09.04
Silicon Anode Morphological Evolution with Lithiation and De-Lithiation
Chonghang Zhao1,Takeshi Wada2,Vincent De Andrade3,Doga Gursoy3,Hidemi Kato2,Yu-chen Chen-Wiegart1,4
Stony Brook University1,Tohoku University2,Argonne National Laboratory3,Brookhaven National Laboratory4Show Abstract
Silicon with its ~10 times theoretical Li capacity compared with carbon-based electrodes, becomes one of the most promising alternative anode materials in lithium-ion batteries. However, its application is challenging due to the more than 400% volume expansion during lithiation, and the subsequent volume reduction during de-lithiation. Nanostructured Si materials have been studied to accommodate the volume change and to mitigate the issues, including Si nanowires, Si nanotubes and nano-porous Si. Here we investigate a novel form of nano-porous Si structure prepared by a liquid metal de-alloying method. The nanopores effectively prevent electrode cracking and therefore ensure long-term durability and stable performance within batteries. However, morphological changes and degradation of the Si nanoporous electrode during charging and discharging are still not fully understood, which limit utilizing this novel electrode with its full capacity. We apply synchrotron-based x-ray nano-tomography to quantify the three-dimensional morphological changes of the nanoprous Si anodes under different cycling conditions. We quantify the evolution of the electrode thickness and the material density distribution within the electrode as a function of electrochemical cycling. The delamination process, the morphological evolution and the degradation of the batteries will be discussed.
EN06.10: Li Metal Anodes
Thursday PM, April 05, 2018
PCC North, 100 Level, Room 121 B
1:30 PM - EN06.10.01
Synthesis and Electrochemical Studies of Metal Fluorides and Nanocomposite Metal Oxides-LiF Materials
M V Reddy1,A Shahul2,Chua Chattrapat1,Stefan Adams1
National University of Singapore1,Qatar University2Show Abstract
Conventional positive (cathodes) electrode materials for lithium-ion batteries, use mixed-conducting lithium containing transition metal oxides, metal phosphates etc. which are able to store both lithium and electrons by changing their oxidation state. In this presentation, we discuss the synthesis of materials suitable for alternative electrode concepts including transition metal fluorides that operate by a conversion type mechanism (1) and a promising new type of alternative nanocomposite composite cathodes, where the storage of lithium and of charge is distributed over two components of a nanocomposite containing LiF and or metal oxides, MO (M= Mn, Fe, Co, Ni, Cu) (2,3).
Transition metal fluorides MF2 (M=Fe, Mn, Zn) were derived from one dimensional metal organic frameworks (MOF) by a polymer (PVDF) assisted decomposition at 600°C, 6h in Ar gas. The MOF were initially prepared by a simple chimie douce method. Incorporation of the MOF with a fluorinated polymer (PVDF) and the eventual decomposition lead to carbon coated metal fluoride nanoparticles of high surface area of >200 m2/g. Electrochemical studies were carried out in the voltage, range 4 to 1.0 Vs. Li, at current rate of 50 mA/g (0.1 C) and preliminary galvanostic cycling of FeF2 demonstrates that the material exhibit stable and good reversible capacity of 580 mAh/g during the initial cycles and slight capacity fading has been observed after 20 cycles. Further optimization of the performance is being carried out. Whereas MnF2 and ZnF2 showed reversible capacity of 220 and 200 mAh/g and retained a capacity around 100 mAh/g after 20 cycles.
Nanocomposites of divalent transition metal oxides MO (M= Mn, Fe, Co, Ni, Cu) and LiF were prepared ball-milling method. The obtained materials will be characterized in detail by X-ray diffraction; Scanning and Transmission electron microscope (SEM/TEM) are used study the morphology. Raman, X-ray photoelectron spectroscopy are used understand structure, vibrational bands and oxidation state of the materials and BET surface area method. Structural and microstructural variations during charge-discharge cycling were characterized by in operando X-ray diffraction for elected promising compositions. Electrochemical properties will be evaluated voltage, range 4 to 1.0 vs. Li in the voltage using cyclic voltammetry at scan rate of 0.075 mV/sec, galvanostatic cycling at a current rate of 0.1C, and electrochemical impedance spectroscopy. Preliminary electrochemical studies yield a reversible capacity of 100 mAh/g. Further long term cycling studies of the nanocomposites are in progress.
(1) Cabana, J etal. .; . Adv. Mater. 2010, 22, E170.
(2) Jung, S.-K.; etal. Lithium-free transition metal monoxides for positive electrodes in lithium-ion batteries. 2017, 2, 16208.
(3) Poizot, P. etal Nano-sized transition-metaloxides as negative-electrode materials for lithium-ion batteries. Nature 2000, 407, 496.
1:45 PM - EN06.10.02
Hermetic Coating Layer for Lithium Metal Anode Through Vapor Deposition
Fang Liu1,Qiangfeng Xiao2,Mei Cai2,Yunfeng Lu1
University of California, Los Angeles1,General Motors2Show Abstract
With the lowest chemical potential and highest energy density among anode materials, lithium metal becomes the most promising candidate for next-generation rechargeable batteries with high energy density. However, its non–uniform electrodeposition behaviors and spontaneous side–reactions with electrolyte components have caused numerous safety concerns and constrained its applications. Through vapor deposition, a hermetic coating layer of silicate can be readily formed on lithium foil under ambient conditions. Such coatings consist of a “hard” inorganic moiety that helps to suppress lithium dendrites and a “soft” organic moiety that enhances the toughness. Lithium–metal batteries, including Li–LiFePO4 and Li–S batteries, made with such coated anodes show significantly improved lifetime. This work provides a simple yet effective approach stabilizing the interface of lithium metal anodes for advanced rechargeable batteries.
2:00 PM - EN06.10.03
Selenium Impregnated Monolithic Carbons as Free-Standing Cathodes for High Volumetric Energy Lithium and Sodium Metal Batteries
David Mitlin1,Jia Ding2
Clarkson University1,State University of New York, Binghamton2Show Abstract
Energy density (energy per volume) is a key consideration for portable, automotive and stationary battery applications. We created selenium (Se) lithium and sodium metal cathodes that are monolithic and free-standing, and with record Se loading of 70 wt%. The carbon host is derived from nanocellulose, an abundant and sustainable forestry product. The composite is extremely dense (2.37 g cm-3), enabling theoretical volumetric capacity of 1120 mAh cm-3. Such architecture is fully distinct from previous Se – carbon nano or micropowders, intrinsically offering up to 2X higher energy density. For Li storage, the cathode delivered reversible capacity of 1028 mAh cm-3 (620 mAh g-1) and 82% retention over 300 cycles. For Na storage 848 mAh cm-3 (511 mAh g-1) was obtained with 98% retention after 150 cycles. The electrodes yield superb volumetric energy densities, being 1727 Wh L-1 for Li-Se and 980 Wh L-1 for Na-Se normalized by total composite mass and volume. Despite the low surface area, over 60% capacity is maintained as the current density is increased from 0.1 to 2 C (30 min charge) with Li or Na. Remarkably, the electrochemical kinetics with Li and Na are comparable, including the transition from interfacial to diffusional control.
2:15 PM - EN06.10.04
Impervious Carbon Nanomaterial Thin Films for Lithium Metal Anode Protection
Gillian Hawes1,Michael Pope1
University of Waterloo1Show Abstract
The lithium-ion battery is the rechargeable power source for nearly all modern portable electronics and electric vehicles, due to its relatively high energy density, negligible memory effect, and minute self-discharge. Despite its widespread use in modern electronics, the drive for a sustainable energy future and applications such as all-electric vehicles, robots, and drones require future batteries to possess much higher energy densities. A major limitation faced by lithium-ion batteries stems from the graphite anode, commonly used due to its stability upon lithiation, which possesses a relatively low capacity compared to next-generation anode materials such as lithium, silicon and lithium alloy materials. Switching to these materials could significantly boost the energy density of lithium-ion batteries and would also enable high capacity next-generation chemistries beyond lithium-ion. Lithium metal in particular is considered the ideal anode material, as it possesses the lowest electrochemical potential and an extremely high theoretical capacity. Still, the implementation of lithium metal anodes is currently impeded by their significant volume change upon charging and discharging, lithium metal’s propensity to grow dendritic structures that can cause dangerous short circuits, and the instability of the solid electrolyte interface that forms upon exposing the anode to electrolyte. Unique nanomaterials can provide a key advancement in the development of high capacity lithium anodes by controlling the transport and storage of ions at the nanoscale. In this work, we investigate several non-porous carbon-based thin films that can act as selectively-permeable lithium-ion membranes and as protective intermediaries between the lithium metal anode and the electrolyte. These coatings serve to block electrolyte, form a stable solid electrolyte interface, and limit the formation of dendrites. We demonstrate the performance of the protected lithium metal anodes in symmetric lithium-lithium cells and in lithium-sulfur batteries, signifying the ability of these protection layers to provide a key step towards safe and highly energy-dense next-generation rechargeable batteries.
3:30 PM - EN06.10.05
Water-Tolerant Lithium Metal Cycling Promoted via Artificial SEI Transplantation
Nikhilendra Singh1,Timothy Arthur1,Ruidong Yang1,Kensuke Takechi1,Robert Kerr2,Patrick Howlett2,Maria Forsyth2
Toyota1,Deakin University2Show Abstract
The ability to directly utilize Lithium (Li) metal anodes in rechargeable batteries presents itself as an ideal, albeit challenging, situation. Li metal used as an anode would provide Li batteries with the maximum possible specific capacity (3860 mAh/g) in comparison to currently used anodes (e.g. graphite – 380 mAh/g). Nonetheless, Li metal anodes remain rare in commercial devices due to inherent safety concerns associated with the formation of Li dendrites during practical rate cycling, as well as Li metals’ susceptibility to exhibit high reactivity towards commercially available organic electrolytes. Due to possibilities of thermal runaway, such concerns have adversely affected the potential use of Li metal. Additionally, Li metal reacts negatively with water which can be found as an impurity in commercially available organic solvents; or passivate in the presence of small quantities of moisture rendering it un-rechargeable. This presents a significant hurdle when water-tolerant Li cycling is warranted (e.g. Li-air). Hence, significant efforts in recent rechargeable battery literature have targeted the development of robust electrolytes, capable of better stability when used with Li metal.
To date, various strategies have been employed to overcome such concerns; the use of solid electrolytes as a mechanical barrier, or the use of specific organic solvent-based electrolytes which control the properties of the solid-electrolyte interface (SEI), being noted observations. Amongst the various classes of Li battery electrolytes developed to date, ionic liquids (ILs) have been utilized as electrolytes which can facilitate enhanced Li cycling efficiencies and favorable Li plating morphologies while being inherently non-volatile/non-flammable alternatives to commercially available organic electrolytes. Through the capability to combine various cations (Imidazolium, Ammonium, etc.) and anions (TFSI, DCA, etc.); the use of such ILs could produce a more adept SEI, resulting in the improved cycling behaviors reported in literature.
Recently, we reported that certain ILs allowed for successful Li metal cycling in the presence of water mixed into the IL. To our knowledge, no reports have shown the capability to sustain morphologically friendly Li deposition upon application of practical cycling rates while allowing for stable cycling in water containing electrolytes. In recognition of this unique capability, we analytically probed the characteristics of the IL SEI’s to understand their protective capability. Based on such understanding, we now introduce a new method to artificially form these SEI’s on Li metal via the screening of various IL combinations. The electrochemical results, along with fundamental analytical analyses of the ILs capable of Artificial SEI Transplantation on Li metal, while sustaining commercially feasible Li morphologies at practical cycling rates in the presence of water containing electrolytes will be presented and discussed.
EN06.11: Anodes II
Thursday PM, April 05, 2018
PCC North, 100 Level, Room 121 B
3:45 PM - EN06.11.01
Intrinsic Safety of Lithium Ion Batteries
Martin Winter1,A. Friesen1,M. Börner1,F.M. Schappacher1
Universität Münster1Show Abstract
Lithium ion battery (LIB) cells are established electrochemical energy storage systems with high Coulombic and energy efficiencies and high energy and power densities [1-3]. Four performance parameters are considered key for the success of future applications: High energy density, fast charging, long cycle life and enhanced safety.
The controlled safe behavior of LIBs is a critical performance requirement for commercial use, especially in large batteries for automotive and stationary energy storage (“grid”) application. In the past years several incidents occurred, that caused public attention to the safety of the technology in general, raising doubts on the implementation of LIBs in large battery applications. Moreover, the progressive development of new materials and advanced cell designs improves the cell performance continuously, but unfortunately the growing energy densities and increasing battery pack sizes raise the safety risks, too.
Measures can be taken on various levels of battery hierarchy to improve safety of LIBs. On battery system level, housing, packaging, thermal and battery management play important roles. On module level, temperature control of sensors and an intelligent battery management system help to improve safety. The cell design has a major influence on the safety of LIB cells. The heat dissipation rate during an exothermal reaction largely influenced by the cell design. If the heat dissipation rate is larger than the heat generation rate of the exothermic reaction, the cell will cool down and not reach a critical state. If the cell gets into a critical state, different safety measures like current interruption devices (CID), positive temperature coefficient elements (PTC) or burst discs are the last measures before the cell chemistry comes into play. The latest incidents with smartphones clearly prove, that we also have to address the cell chemistry. The intrinsic safety of LIBs is influenced by the anode and cathode active materials, as well as the inactive materials, like electrolyte and separator. The usually used liquid electrolyte is the most critical compound as it is volatile, flammable and in contact with every part of the LIB cell . In addition, the electrolyte does decompose forming toxic components .
In this presentation, we will focus on intrinsic cell safety and the prominent role of the electrolyte. We will show how different additives influence the different components of a LIB cell and cell safety.
 Wagner R, Winter M, et al., J. Appl. Electrochem., 2013, 43 (5), 481-496
 Placke T, Winter M, et. al. J. Solid State Electrochem., 2017, 1-26, DOI: 10.1007/s10008-017-3610-7
 Meister P, Winter M, Placke T, et. al. Chem. Mater., 2016, 28, 7203-7217
 Schmitz R W, Winter M, et. al. Prog. Solid State Ch., 2014, 42, 65-84
 Nowak S, Winter M, J. Electrochem. Soc., 2015, 162, A2500-A2508
4:15 PM - EN06.11.02
Stacked-Graphene Layers as Engineered Solid-Electrolyte Interphase (SEI) Grown by Chemical Vapour Deposition for Lithium-Ion Batteries
Taehoon Kim1,Luis Ono1,Matthew Leyden1,Yabing Qi1
Okinawa Institute of Science and Technology1Show Abstract
Lithium-ion layered structure continues to have immense appeal as a promising electrode material for rechargeable batteries owing to its superior capability of intercalation and deintercalation of lithium-ions per compound unit. However, this type of electrode suffers from the irreversible capacity loss resulting from solid-electrolyte interphase (SEI) formation and surface reconstruction by electrolyte reactions. To overcome the inherent limitations relevant to the layered structure, a multi-layer of stacked-graphene (8-layers) grown by chemical vapour deposition (CVD) is introduced perpendicular to the basal planes. Although the basal planes are generally regarded as a physical barrier to the lithium-ion diffusion, lithium-ions are likely to be intercalated into the planes through defect sites of the CVD grown graphene. The clap-net like design of the graphene treatment effectively isolates the inward environment, where the electron conduction takes place, from the outer system where the undesired redox reactions occur by the electrolyte. This engineered interface with the stacked-graphene not only preserves the initial local-atomic environment of the active material, but also renders the electrode/electrolyte interface to be stable for dynamic charge rates change. The current study sheds some light on developing battery electrodes that suppresses the surface reconstruction of the active material, leading to stable SEI formation.
4:30 PM - EN06.11.03
The Mismatch Between Charge and Formal Oxidation State of Titanium in Titanium Dioxide and Its Implications Towards Our View of Redox Processes
Daniel Koch1,Pavlo Golub1,Sergei Manzhos1
National University of Singapore1Show Abstract
Titanium dioxide (TiO2) polymorphs are promising electrode materials for Li-ion and Na-ion batteries, due to their potentially high capacity, cycling stability and charge/discharge rate. The mechanistic understanding of redox processes, involving compounds like TiO2, in terms of formally defined charge transfers between the involved reactants is, by definition, based on the change of the oxidation states of the involved species. Although the way formal oxidation states are determined can be justified by a variety of valid arguments, the implications that come with them, especially with regard to redox processes, might be counter-intuitive and of little practical use. The charge state of titanium in titanium dioxide is commonly assumed to be +4, which is the basis for any description of redox processes involving this material. Previous investigations on the other hand (e.g. Nature 453 (2008) 763) showed that the physical charges on transition metal atoms are generally little affected by changes in their formal oxidation states. We concluded in comprehensive investigations on TiO2 molecules and TiO2 bulk crystals, using different quantum theory of atoms in molecules (QTAIM) approaches like Bader charge analysis or delocalization indices, a lower charge state (+3).
Moreover, a recent investigation (Organometallics 36 (2017) 622) using charge reporter molecules concluded a remarkable stability/similarity of charge states of many transition metal atoms, including titanium, in different environments corresponding to very different formal oxidation states. Ab initio investigations carried out by us on titanium carbonyl complexes support this experimental findings. Furthermore, our QTAIM charge analyses on titanium for its intercalation into p-doped crystals and in titanium halides confirm the similarity of the Ti charge in different environments and do not suggest that the charge state of titanium reaches the ideally assumed Ti4+ in other common Ti(IV) compounds commonly classified as ionic. All of this makes the possibility of further Ti oxidation or O reduction in terms of charge density increase or depletion around the corresponding nuclei, at least in a theoretical framework, possible, as it was seen in our analyses on simple model systems.
4:45 PM - EN06.11.04
Self-Organized Nano-Structured Silicon as Anode Material for Li-Ion Batteries
Wim Soppe1,2,Christiaan Rood2,Frans Ooms3,Mario Marinaro4
ECN - Solliance1,LeydenJar Technologies2,Technical University of Delft3,ZSW4Show Abstract
Silicon is an ideal anode material for Li-ion batteries, provided it can accommodate the large volume changes between charging and discharging. We present a method, based on Plasma Enhanced Chemical Vapor Deposition (PECVD), to create self-organized nano-structured silicon layers, which can accommodate the large volume changes. Large advantage of this method is that it does not require any pre- or posttreatment of the silicon to obtain the nano-structuring and high porosity. The nanometer scale porosity of these layers can be tuned between 30 and 70%, leading to specific areas of more than 200 m2/g (as measured by BET analysis).
The layers are deposited in a pilot roll-to-roll PECVD deposition system, in which we can handle foils with a width up to 30 cm. The linear plasma sources, however, can be easily extended to a width of more than 1 meter, offering perspectives to cost-effective high throughput mass production of the silicon layers.
We tested this material both in half cells with Li counter electrode and in full cells with an NMC cathode, with a silicon mass load of approximately 1 mg/cm2. Half cells, charged at 1000 mAh/g at C/5 show no capacity fading and a CE of 99.5% after more than 350 cycles, using a standard electrolyte LiPF6 containing FEC. Small pouch cells (3x3 cm2) could be charged/discharged more than 100 cycles at 1000 mAh/gSi without capacity fading but with a CE of about 98%. Further improvement of the lifetime is expected through modifications of the electrolyte to increase the Coulombic efficiency in full cells.
EN06.12: Poster Session II
Thursday PM, April 05, 2018
PCC North, 300 Level, Exhibit Hall C-E
5:00 PM - EN06.12.03
Flexible All-Solid-State Li-Te Safe Batteries
Huazhong University of Science & Technology1Show Abstract
Recently, the fast-growing market for portable electronic devices, electric vehicles (EVs) and flexible devices has placed great demands on rechargeable batteries with high energy/power density, security and flexibility. Tellurium, an element in the chalcogen family, which possesses the highest electronic conductivity among all non-metallic elements, has more advantages over sulfur and selenium, such as high utilization rate and better kinetics during charge/discharge process. However, the conventional carbonate electrolyte for Li-Te batteries does not work well and faces many inevitable security problems, such as inflammability and explosion. In this paper, single crystalline tellurium (Te) nanotubes grown on carbon fiber cloth (Te/CFC) conductive substrates have been prepared by a chemical vapor deposition (CVD), which are used as the cathode for flexible all-solid-state lithium-tellurium (Li-Te) rechargeable batteries with high safety. A high gravimetric capacity of 316 mA h g-1 and a volumetric capacity of 1979 mA h cm-3 after 500 cycles at a current density of 100 mA g-1 can be obtained, respectively.
5:00 PM - EN06.12.04
Toward a Dendrite Free, Powder Compact-Based Solid Electrolyte Lithium Metal Battery—Interfacial Modification
Ran Zhao1,Ryan Gebhardt1,Alison Whale1,Guantai Hu1,Steve Martin1
Iowa State University1Show Abstract
Owing to its high energy density and light weight, Li-ion batteries have taken away over half of the worldwide rechargeable battery market. However, the safety issues of Li-ion batteries that originate from the combustible organic electrolyte are of great concern recently. Solid-state batteries using powder compact solid electrolytes (PCSE) are promising options toward safer and higher energy density batteries due to the utilization of inorganic electrolyte and metal lithium as anode, however, the high solid-solid interfacial resistance between the lithium metal and the solid electrolyte is still a challenge.
In this work, we demonstrate reversible plating and stripping of dendrite-free metallic-lithium with a reduced anode/PCSE interfacial resistance by introducing a thin interfacial layer formed by heating. First, the PCSE which has an ionic conductivity of ~ 10-4 S/cm at room temperature, was synthesized by mechanical milling, and characterized using NMR, DSC, IR spectroscopy, and Raman spectroscopy. Next, the PCSE was tested in symmetric cells for electrochemical impedance spectroscopy and cycling. To address the high solid-solid interfacial resistance and short-circuiting dendrite problems, we demonstrate a simple strategy to engineer the lithium-PCSE interface by forming an in-situ interlayer via a heat treatment. The area specific resistance of 573.6 Ω/cm2 has been successfully achieved with a 0.9 mm thickness pellet under a current density of 0.1 mA/cm2. These results provide a promising PCSE membrane that can be applied to lithium metal battery and other energy storage application, such as lithium sulfur batteries.
5:00 PM - EN06.12.05
In Situ Fabricated Carbon-Polyimide Hybrid Film Providing Mechanical and Electrical Robust Network for LIB Silicon Anode
Goojin Jeong1,Hyunwoo Cho1,KyungSu Kim1,Cheol-Min Park2
Korea Electronics Technology Institute1,Kumoh National Institute of Technology2Show Abstract
Engineering of composite electrode for silicon anode materials plays an important role in the practical application of Si-based lithium-ion batteries (LIB). In this work, a hybrid composite anode of silicon-carbon-polyimide was in-situ fabricated by proper heat treatment of the slurry coat containing silicon power and polyamic acid polymer, without any carbon agent. The resulted film shows three components (silicon-carbon-polymer) composite structure wherein the hybrid carbon-polyimide is in-situ generated from polyamic acid by proper heat treatment. The hybrid Si composite exhibits robust binding and conductive properties, and also meso/macroporous internal structure enabling it to buffer Si volume expansion. When applied as LIB anode, it deliveres promising battery performance with little volume change even under high content of Si (>96wt%), which implies that the in-situ fabricatoin method could be another effective way for Si anode engineering for high energy density LIB.
5:00 PM - EN06.12.07
Using Thermal Behavior as an Indicator to Enhance the EIS Analysis for Lithium-Ion Battery System
Bo Dong1,Yige Li1,Kazi Ahmed1,Cengiz Ozkan1,Mihri Ozkan1
University of California, Riverside1Show Abstract
Electrochemical Impedance Spectroscopy (EIS) has been proved to be a very powerful technique to investigate the interfacial electrochemical dynamics within various kinds of electrochemical systems. However, using EIS to study the lithium-ion battery systems is not mature and reliable enough to analyze the State of Charge (SOC) and State of Health (SOH) of the batteries alone. Since EIS is a frequency related technique and the elements inside the battery system are also frequency related, by monitoring the internal temperature profile during the EIS period, more detailed and accurate analysis of the EIS results can be attained without adding any other time consuming and cycling techniques. In our study, temperature variation pattern has been found for different EIS tests during the whole aging process, and improvement for EIS analysis has been reached.
5:00 PM - EN06.12.08
High Energy Density, Thin and Flexible Printed Metal Air Batteries for Flexible Electronics
University of Washington1Show Abstract
High energy density, thin and flexible batteries are a critical component of flexible electronics. Metal air chemistries are particularly attractive for flexible electronics applications as they eliminate the need for thickness-adding packaging and capacity-limiting cathode volumes. Here we demonstrate the first fully printed ultrathin metal air batteries from solution processed cell layer materials that enable monolithic layer by layer stencil printing. Printed cell layers include the current collector, a zinc alloy composite electrode, a solid ionic liquid/polymer electrolyte and an oxide nanocatalyst-decorated reduced graphene oxide(r-GO) /carbon nanotube(CNT) composite cathode. The carbon nanotube/graphene catalyst mixture layer self aseembles into hierarchical porous structure with MnCo2O4 nanoparticles(~10nm) decorated r-GO flakes(2-4 layers) covering the surface of CNT bundles(~50μm). We utilized the hierarchical nanostructures to maximize the number of reaction active sites while maintaining sufficient electrical percolation and air access to the catalytic sites in the cathode. The The low vapor pressure of ionic liquid enables thermal processing temperatures of 80°C. The printed metal air batteries exhibit high thin cell volumetric capacities of 170 mAh/cm3, areal capacities of 2.0 mAhr/cm2 from a total cell thickness of 150 micron. This is among the very highest areal capacity batteries demonstrated to date and relies on air stable, low cost and low toxicity printed Zn air / solid polymer electrolyte chemistry. The batteries are bendable and lightweight and are well positioned as a promising power source of flexible electronics and next generation wearable and on-body electronics.