Advanced Materials for Energy Conversion and Storage: Energy Storage II
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Amit Pandey, LG Fuel Cell Systems Inc.

Wednesday 8:30 AM
March 1, 2017
Room: 15A
Location: San Diego Convention Ctr

Session Chair: Partha Mukherjee, TAMU; Leela Arava, Wayne

8:30 AM  Invited
In-situ X-Ray Diffraction Analysis of Li-ion Battery Materials: Scott Speakman1; 1PANalytical
    In-situ X-ray diffraction is capable of monitoring phase changes and microstructural evolution produced by lithium migration during discharge and recharge of batteries. As an example, Ni-rich cathode materials display an unexpected intermediary phase between the fully charged and discharged states which may be tracked to aging and degradation of battery performance. This intermediary phase cannot be observed without in-situ analysis. The choice of in-situ electrochemical stages and diffraction geometry highly influences the cross-section of battery materials and behavior that can be observed. New developments in optics and detectors allow researchers to select between reflection and transmission geometries through button cell and pouch cell designs. This design will present data from collaborations analyzing several different Li-ion systems and will discuss the advantages and disadvantages of diffraction geometries and sample stage design.

8:55 AM  Invited
Mesoscale Probing of Transport-Interface Interaction in Lithium-Ion Battery Electrodes: Partha Mukherjee1; Aashutosh Mistry1; 1Texas A&M University
    Lithium-ion battery electrodes represent complex porous composites, consisting of multiple phases including active material, conductive additive, polymeric binder, and electrolyte. The electrode microstructure poses profound influence on the underlying electrochemical-transport-interface interaction. The aim of this mesoscale study is to probe the electrode microstructural effect on the electrochemical properties and interface interaction. The results reveal a complex non-linear behavior in the effective electrical conductivity. The microstructural heterogeneity further leads to ion-blockage and pore-phase transport resistance coupling. This study highlights the role of mesoscale interaction on the underlying short-range (i.e. interface) and long-range (i.e. transport) combinatorial complexations in lithium-ion battery porous electrodes.

9:20 AM  
Novel Three Dimensional Porous Sn-Sb-Ni Anode on Ni Foam: Electrodeposition Synthesis and Lithium Storage Performance: Srijan Sengupta1; Arghya Patra1; Arijit Mitra1; Mainul Akhtar1; Karabi Das1; Subhasish Basu Majumder1; Siddhartha Das1; 1IIT Kharagpur
    We report a novel, active-inactive type Tin-Antimony-Nickel alloy with flaky morphology electrodeposited on 3D interconnected microporous Nickel foam (~30 μm pore diameter) as a promising high-specific-capacity anode for Li ion batteries. The multiphase composition (SnSb and Ni3Sn4 “reactant” intermetallics dispersed in Tin “matrix” with 43.52% Sn, 24.70% SnSb, 14.03% Ni3Sn4 and 17.75% Ni) alleviates the volumetric stress generated during cycling by lithiating at different potentials (0.84V, 0.66V, 0.57V, 0.42V, 0.39V and .35-.25V). Nickel foam provides effective electron pathways and successfully acts as a stress buffer preventing delamination and pulverisation. These combinations of properties in Tin-Antimony-Nickel anode on Nickel foam results in a higher reversible capacity (834.38 mAh/g at 200 mA/g after the 2nd cycle and 70% capacity retention after 100 cycles), superior rate capability and stable cycle retention while preserving its structural integrity in comparison to a Tin-Antimony-Nickel anode on a planar nickel foil as a current collector.

9:40 AM  Invited
Phase Field Studies of Mechanical and Electrochemical Behavior of Li-ion Battery Electrode Materials: Bai-Xiang Xu1; Ying Zhao1; Peter Stein1; 1TU Darmstadt
    In pursuit of larger capacity, potential materials such as Si, Sn, and Sb have been introduced as alternative anode materials to graphite in Li-ion batteries. However, those electrodes experience irreversible mechanical degradation already after few charge/discharge cycles due to high stresses. Nanostructured electrodes have been shown to have a better performance and a higher robustness against the internal degradation processes. This is accompanied by strong size- and shape- effects, which are attributed to surface effects on small scales. A phase-field model and FE simulation results are presented in this talk to demonstrate the mechanical behavior and electrochemical process of electrode particles. Phase segregation and fracture behavior during lithiation and delithiation in Si particles are simulated. The electrochemical reactions on exterior and interior surfaces and surface tension are considered. Results reveal the influence of charging/discharging conditions, particle size and geometry, elastic properties and diffusitivity.

10:05 AM Break

10:25 AM  
Stable Li-Sn Electrode: Jonathan Phillips1; Tongli Lim1; Pol Vilas2; 1Naval Postgraduate School; 2Purdue University
    Using Reduction Expansion Synthesis (RES) 10 wt % Sn/C electrodes were generated on some commercial high surface area carbons. Li was added to these materials in a half cell, and on some carbons after more than 50 cycles virtually no loss of activity, ~315 mAh/g total electrode, was observed. Similarly, Na ions were added to a sample of the same material, and it too proved totally stable, but at only 205 mAh/g. The improvement in stability relative to all Sn based electrodes in the literature is tentatively tied to enhanced direct (no O or S linkage)bonding between metal and carbon, a conclusion consistent with both XRD and TEM which show particles of order 5 nm form from the thermal decomposition(~800 C) under flowing inert gas of a physical mix of urea and Sn precursor, i.e. RES-process.

10:45 AM  Invited
Towards The Development of Solid-State Batteries: Addressing the Challenges in Replacing Liquid with Solid Electrolytes and Enabling Li Metal Anodes: Jeff Sakamoto1; 1University of Michigan
    Large-scale adoption of electric vehicles requires batteries with higher energy density, lower cost, and improved safety compared to state-of-the-art (SOA) Li-ion technology. While there are efforts to discover new electrolytes with high conductivity, there are several existing solid electrolytes that have some of the necessary attributes to enable solid-state batteries. Ceramic electrolytes represent one class of solid electrolyte that exhibits the unprecedented combination of stability against Li, high ionic conductivity, and adequate mechanical properties to suppress Li dendrite formation, among several other key features. Owing to the recent attention ceramic electrolytes have garnered, this presentation summarizes key findings, highlights the challenges, and discusses the future outlook for solid-state Li-ion conducting electrolytes. The following aspects will be discussed: 1) Li-ion conductivity, 2) phase stability, 3) chemical and electrochemical stability, 4) mechanical properties, and 5) cell integration.

11:10 AM  
Studying Transport Mechanisms of Li in Graphite Polycrystals via Atomistic Simulations: Christopher Shumeyko1; Ed Webb2; 1Lafayette College; 2Lehigh University
    Numerous works in recent years have exposed vast differences in ion diffusion rates in graphitic anodes of Lithium-ion batteries, ranging by several orders of magnitude. While explanations have focused on concentration effects, our computational studies elucidated grain boundary (GB) character as a driving force for differences in ion intercalation rates. For fully-lithiated polycrystals, however, concentration effects suppressed GB transport, despite geometrical boundary differences. Current work aims to further investigate transport mechanisms during intercalation as a means to reveal anisotropies in the structural response of such polycrystals. Such anisotropic performance may initiate anomalous anode performance that is associated with macroscopic battery failure. Interplanar (GB) versus intraplanar (gallery) Li transport mechanisms are vastly different and understanding characteristic behaviors that drive GB transport are critical. Intercalation behavior observed in our atomistic models is subsequently interpreted via analytical diffusion models.

11:30 AM  
Inelastic Shape Changes of Silicon Particles and Stress Evolution at Binder/Particle Interface in a Composite Electrode during Lithiation/Delithiation Cycling: Siva Nadimpalli1; Vivek Shenoy2; Hailong Wang2; 1New Jersey Institute of Technology; 2UPenn
    Stress evolution in Si-binder composite was modeled using diffusion induced stress framework available in finite element software. A simple model that contains two spherical Si particles with and without the polymer binder film was considered. The particles were lithiated/delithiated at two different rates: one representing a slow charging case which results in a uniform Li concentration throughout the Si particles and the other representing a fast charging condition which results in non-uniform lithium concentration within the spherical Si particles. The inelastic shape changes and associated contact forces predicted by the model are qualitatively consistent with experimental data. Further, the effect of binder mechanical properties and the binder fraction on the stress evolution was calculated. The proposed model, although simple, can guide a battery design engineer to choose a proper binder, charge/discharge strategy, and binder fraction for a durable electrode design.

11:50 AM  Invited
Electrocatalysis Approach to Lithium Sulfur Batteries: Leela Mohana Reddy Arava1; 1Wayne State University
    Stabilizing polysulfide-shuttle process while ensuring high sulfur loading holds the key to realize high theoretical energy density (2500 Wh/kg) of lithium-sulfur (Li-S) batteries. Though several carbon based porous materials have been used as host structures for sulfur and its intermediate polysulfides, the week adsorption of polysulfides on carbon surface and its poor reaction kinetics limits them from practical application. Here, we preset a novel ‘electcatalysis’ approach to stabilize polysulfide shuttle process and also enhance its red-ox kinetics. Nature of electrocatalyst, pore-size distribution, concentration of polysulfides, temperature of the cell etc., on electrochemical properties will be discussed. We reveal substantial improvement in electrochemical properties such as specific capacity, rate capability, coulombic efficiency etc. and corroborate our findings with systematic experimental studies. Interaction between electrocatalyst and polysulfides has been evaluated by conducting X-ray photoelectron spectroscopy and electron microscopy studies at various electrochemical conditions. Thus, introducing a catalyst in the Li−S system will open a new avenue for improving electrochemical performance.