Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session A21: Energy Storage - Electrode Physics |
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Sponsoring Units: GERA Chair: Ernesto Marinero, Purdue Univ Room: 302 |
Monday, March 2, 2020 8:00AM - 8:12AM |
A21.00001: Anion charge dependent lithium ion diffusion in solids Zhenming Xu, Hong Zhu Our recent studies of the chalcopyrite-structured sulfides and non-spinel-structured halides show that the lithium-ion migration energy barrier can be effectively reduced by comprehensively regulating the anion charge and lithium-ion coordination environments. For example, for lithium ion diffusion between two adjacent lithium-anion octahedrons through a tetrahedral transition state, the greater the anionic charge is, the lower the lithium ion diffusion energy barrier will be. While for lithium ion diffusion between two adjacent lithium-anion tetrahedrons through an octahedral transition state, the smaller the anion charge is, the lower the lithium ion diffusion barrier will be. This new understanding of comprehensively regulating the anion charge and lithium-ion coordination environments to enhance lithium ion transport can be applied for the design and optimization of new superionic conductors. |
Monday, March 2, 2020 8:12AM - 8:24AM |
A21.00002: Stable Ionic Conductive Layer on Si Nanoparticles inside Si/C Composite for High-Performance Lithium-Ion Battery Anode Yong Su Kim, Heechul Jung, Jucheol Park, Seong Heon Kim In this study, we developed a simple and effectual method to form the stable Li ionic conductive layers for Si-based LIB anode materials. (1) For the purpose of maintaining a Li ionic conductive solid electrolyte interphase (SEI) during operation, the protective oxide coating for Si/C composite is practical, which can be simply applied by mixing a poly(vinyl alcohol)-PO4 with the Si/C composite. The in-depth analysis revealed that the oxide coating reduces the loss of high ionic conductive SEI (Li2O), resulting in the formation of a stable SEI [1-2]. (2) In the manufacturing step, stable Li ionic conductive layer (Li2SiO3) can be successfully fabricated on the Si nanoparticles inside Si/C composite by simply mixing the Li2O nanoparticles with coal tar pitch. From the electrochemical measurements applied to various cells, it was demonstrated that the Si/C composite with stable Li2SiO3 layers show a considerably high performance in stability [3]. The design of this study and analysis provides the direction to enhance the stability of Si-based anode materials at low cost for developing high performance LIB. |
Monday, March 2, 2020 8:24AM - 8:36AM |
A21.00003: Creating a Chevrel Hybrid Mo6S8-ySey to Improve the Performance of Beyond Li-Ion Batteries Taylor Juran, Manuel Smeu Attempting to solve the energy crisis, we consider the use of beyond Li-ion batteries. We are especially interested in the use of Ca and Al metals, due to their abundance within Earth’s crust. Ca and Al are more cost-effective, and environmentally friendly than Li. Additionally, the increased valency increases the energy density. We consider the Chevrel phase (CP), Mo6X8 where X= S, Se, Te, as a cathode for Ca-ion batteries. The CP cathode has widely been studied as a cathode for multivalent ion batteries. Several studies have shown that changing the chalcogen X, impacts the potential and diffusion kinetics. Literature shows that the S-rich CP yields a high voltage, with sluggish ion mobility; compared to the Se-rich CP which exhibits a lower voltage and improved ion mobility. We evaluate several S/Se chalcogen concentrations, testing 256 unique configurations, to tune both the potential and diffusion kinetics. Density functional theory is used to investigate the electronic properties, stability, diffusion kinetics, and voltage properties of CaMo6S8-ySey, where y = 0-8. We implement the SCAN functional, a meta-GGA for an improved level of theory. |
Monday, March 2, 2020 8:36AM - 8:48AM |
A21.00004: An in situ Study of Solid Electrolyte Interface (SEI) Formation on Tungsten Thin Film Electrodes by Neutron Reflectometry with Contrast Variation Joseph Dura, Eric D. Rus Solid-electrolyte interphase (SEI) formation in LiPF6 in mixed DEC/EC electrolytes was studied in situ by neutron reflectometry (NR) with scattering length density (SLD) contrast variation of the solvent. Tungsten, a non-Li-intercalating material, was used as the working electrode to greatly improve sensitivity to the SEI vs earlier studies.1 A two-layer SEI was formed upon polarization to +0.25 V vs. Li/Li+. Insensitivity of the inner SEI layer to solvent deuteration at this potential suggested limited incorporation of hydrogen atoms from the solvent molecules. Its low SLD indicated Li2O could be a major constituent. The outer SEI layer SLD scaled with that of the solution, indicating it either had solution filled-porosity or incorporated hydrogen from the solvent, or both. Returning the electrode to +2.65 V removed lithium from both SEI layers, though the effect was more pronounced for the inner SEI layer. Potential cycling increased the solution-derived species content in the inner SEI and decreased the contrast between the outer and inner layers, possibly indicating intermixing of the layers. |
Monday, March 2, 2020 8:48AM - 9:00AM |
A21.00005: Aqueous Solutions at Graphitic Interfaces: Effects of Charge Transfer, Ion Hydration, and Confinement on Interfacial Structure and Capacitance Cheng Zhan, Maira R Ceron, Steven A Hawks, Minoru Otani, Brandon Wood, Michael Stadermann, Patrick G Campbell, Tuan Anh Pham Improved understanding of aqueous solutions at charged graphitic interfaces is critical for designing new carbon-based materials for energy storage. However, many mechanistic details remain unclear, including how interfacial structure and response are dictated by intrinsic properties of solvated ions under applied voltage. Here, we combine first-principles simulations with electrochemical measurements to investigate adsorption of several alkali-metal cations at the interface with charged graphene and within graphene slit-pores. We confirm that adsorption energy increases with ionic radius, while being highly dependent on pore size under confinement conditions. In addition, in contrast with conventional electrochemical models, we find that interfacial charge transfer contributes non-negligibly to this interaction and can be further enhanced by confinement. Overall, the measured interfacial capacitance trends result from a complex interplay between voltage, confinement, and specific ion effects--including ion hydration and degree of charge transfer. |
Monday, March 2, 2020 9:00AM - 9:12AM |
A21.00006: Stone-Wales type defect induced performance enhancement in BC3 monolayer for Lithium-ion battery anode applications Siby Thomas, Mohsen Asle Zaeem Based on first-principles density functional theory (DFT) simulations, we systematically explored the possibility of pristine and defective two-dimensional boron carbide (BC3) monolayer for designing high-performance Li-ion battery (LIB) anodes. Our calculations show that the BC3 monolayer possesses significant structural and electronic stability and also noticed that after adsorbing Li atom, the semiconducting characteristic of both pristine and defective BC3 monolayer is transformed into a metallic state, becoming an electrical conductor, which provided enhanced conductivity for LIB application. Our results reveal the Li adsorption in these structures are exothermic and the Stone-Wales type defect filled BC3 shows a higher theoretical specific capacity of 1287 mAhg-1 for Li atoms compared to pristine BC3 (1144 mAhg-1) and conventional graphite anode (372 mAhg-1). We also found that both the pristine and defect filled BC3 possess fast Li mobility with a low diffusion barrier (~ 0.33 eV) as well as a low average open-circuit voltage (< 0.48 V). Because of these excellent properties, our work predicts that the experimentally synthesized BC3 monolayer, especially the one with Stone-Wales defect can be a promising anode material for the development of future LIBs. |
Monday, March 2, 2020 9:12AM - 9:24AM |
A21.00007: Structures Properties of Li-S Redox Solid Products Kah Chun Lau, Qing Guo, Ravindra Pandey Among the candidates for high gravimetric energy storage beyond Li-ion battery technology, Lithium-Sulfur (Li-S) battery is considered one of the promising candidates owing to its high gravimetric capacity, and earth-abundant reactant materials (i.e. sulfur). However, despite these attractive attributes, successful commercialization of Li−S batteries is currently hindered by poor cycling performance and capacity retention that is primarily caused by our limited understanding of the Li-S redox products at the level of the nanoscale and atomistic scale. To help us to understand the related materials properties, the state-of-the-art atomistic simulation can be a timely solution. In this talk, I will share with you some of our recent theoretical studies in Li-S redox solid products (e.g. Li2S2, Li2S3) structures properties using first-principles calculations that focus on the fundamental structure-property (e.g. thermodynamic stability, vibrational, mechanical and electronic properties) prediction of these new Li-S solid compounds. The underlying materials properties related design rules and the implications to Li-S battery cycling performance will be discussed. |
Monday, March 2, 2020 9:24AM - 9:36AM |
A21.00008: Insights into the electrochemical behavior of layered oxides intercalated with Na or K Jonas Kaufman, Michael Toriyama, Anton Van der Ven Layered transition-metal oxides, like those used in Li-ion batteries, remain popular candidate electrode materials for the emerging, low-cost Na- and K-ion battery technologies. However, shuttling the larger Na/K ions into and out of these compounds leads to two effects less commonly seen with Li: phase transitions between different stackings of the oxide layers and strong ion-vacancy orderings. Both phenomena are often detrimental, as they can result in mechanical degradation and sluggish ionic transport. To understand this behavior, we have performed first-principles studies of the layered NaxCoO2 and KxCoO2 cathode materials using configurational cluster expansions trained on density functional theory energies. We obtain excellent agreement with the experimentally observed voltage profiles and phase transitions upon cycling. In both systems, we predict several families of stable hierarchical orderings made up of antiphase boundaries between similar ordered regions. We find that K stabilizes unusual distorted phases at high concentrations due to strong K-K repulsion. Our results have important implications for diffusion and may be extended to other layered intercalation compounds. |
Monday, March 2, 2020 9:36AM - 9:48AM |
A21.00009: Computational modelling studies on discharge of nanoporous spinel LiMn2O4 Phuti Ngoepe Porosity plays an important role in the performance of Li-ion batteries. Simulated amorphisation recrystallisation methods [1], based on molecular dynamics methods, were used to generate nanoporous LixMn2O4 spinels of approximately 25000 atoms, with different pore sizes. The resulting structures were discharged by lithiation in the concentration range x=1 to 2, and were characterised from XRDs, microstructures and mechanical properties. Generally a transition from the cubic to tetragonal spinel was observed in the range of x=1.5 to 2. In particular, at x=1.75 a broadening of XRD peaks, multiple grain boundries and a reduction in the yield stress were noted. A pore size that minimises such effects was identified together with associated heterostructures. |
Monday, March 2, 2020 9:48AM - 10:00AM |
A21.00010: Influence of Structural Defects on the Electrochemical Properties of MnO2 in Rechargeable Zn/MnO2 Alkaline Batteries: An Ab Initio Study Nirajan Paudel, Birendra Ale Magar, Timothy N. Lambert, Igor Vasiliev Electrical energy storage is essential for seamless integration of intermittent renewable energy sources into the power grid. Rechargeable alkaline Zn/MnO2 batteries are attractive for large-scale electrical energy storage due to their high energy density, non-toxicity and low cost. The performance of MnO2 electrodes in Zn/MnO2 batteries can be enhanced by nanostructuring and by introducing defects into the crystal structure of MnO2. However, the mechanism of this enhancement is not fully understood. We apply first-principles computational methods based on density functional theory to study the mechanism of hydrogen ion insertion into the crystal structures of pyrolusite (β), ramsdellite (R), and nsutite (γ) MnO2 polymorphs containing oxygen and cation vacancies. Our calculations show that the presence of oxygen and cation vacancies significantly changes the binding energies of hydrogen ions inserted into the structures of MnO2 polymorphs. The results of our study could explain the influence of structural defects on the electrochemical properties of MnO2 in rechargeable Zn/MnO2 batteries. |
Monday, March 2, 2020 10:00AM - 10:12AM |
A21.00011: Novel states in transition metal oxides: a view based on high-efficiency RIXS of battery electrodes Wanli Yang To meet today's energy storage requirements for sustainable energy applications, battery electrodes based on transition-metal oxides have been pushed towards very high voltages to achieve a high-energy and high-capacity battery. Such an approach drives the system into a highly oxidized states, which fundamentally leads to stability issues of the battery device. On the other hand, this unconventional state provides a unique playground for studying atypical states in transition metal oxides. |
Monday, March 2, 2020 10:12AM - 10:24AM |
A21.00012: Computational modeling of two-dimensional materials for sustainable energy storage Dibakar Datta, Vidushi Sharma Two-dimensional materials (2DM) such as graphene, transition metal dichalcogenides (TMD), MXenes, and their heterostructures are among the most promising electrode candidates for radically advanced batteries. In this talk, two important computational aspects of 2DM-based batteries are addressed – (i) 2DM-based anode materials, and (ii) 2DM as van der Waals (vdW) slippery interface. The conventional anode materials have several problems, such as low gravimetric capacity and high volume expansion. We demonstrate that topologically modified 2DM can be utilized as high-capacity anode materials for Li-, Na-, and Ca-ion batteries with a capacity of 1675, 1450, and 2900 mAh/g. Moreover, by building heterostructures made by the stacking of different 2DMs, it is possible to combine the advantage and eliminate the disadvantages of the individual materials. The second part of the talk discusses the interface of anode and current-collector. To combat the issue of high-stress generations at anode-current collector interface during intercalation and deintercalation, we propose the usage of the graphene layer over the current collector as a vdW slippery interface. The computational results are in good agreement with the experimental findings. |
Monday, March 2, 2020 10:24AM - 10:36AM |
A21.00013: Crosslinkable Nitroxide Radical Polymer for Energy Storage Applications Shaoyang Wang, Alexandra D Easley, Fei Li, Jodie Lutkenhaus Due to the amount of waste generated by lithium-ion batteries disposal, a more environmentally friendly option such as organic batteries is desired to fulfill the need of this large market. Redox-active radical polymers such as poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) are popularly studied as electrode materials for organic batteries. However, linear PTMA may dissolve in the electrolyte and thus degrade the battery‘s capacity over time. Therefore, crosslinked PTMA is gaining interest as one solution to this challenge. |
Monday, March 2, 2020 10:36AM - 10:48AM |
A21.00014: Highly Mesoporous Carbon Aerogel as Catalyst Support in Proton Exchange Membrane Fuel Cells Eric Kim, Kevin Gu, Sunil Sharma, Stoyan Bliznakov, Miriam Rafailovich Carbon aerogel possesses unique structural and electrical properties, such as high mesopore volume, large specific surface area, and high electrical conductivity, which make it suitable for use as catalyst support in Proton Exchange Membrane Fuel Cell (PEMFC). In this study, we present a novel synthesis of highly mesoporous carbon aerogel via freeze-drying approach and investigate its application in the fuel cell. The structural effects of activation on carbon aerogel will also be discussed. The TEM and XRF, NLDFT and BJH analysis were carried out to observe the morphology and pore structure. Pt on carbon aerogel and activated carbon aerogel show efficient activity in both ORR and HOR reactions compared to Pt on Vulcan XC-72, with increases up to 721% and 194% in specific power density, respectively. The enhanced performance of carbon aerogel is attributed to its large specific surface area, high mesopore to micropore ratio, and even dispersion of catalyst particles. Accelerated stress tests show that carbon aerogel has comparable durability with Vulcan XC-72, while activated carbon aerogel is less durable than both materials. Thus, this mesoporous carbon aerogel provides an efficient, cost-reduced alternative to existing microporous carbon material as catalyst support in PEMFC. |
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