Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session A20: Focus Session: Physics of Energy Storage Materials I -- Cathodes and Electrolytes |
Hide Abstracts |
Sponsoring Units: FIAP/DMP GERA/DCOMP Chair: Donald J. Siegel, University of Michigan Room: D168 |
Monday, March 21, 2011 8:00AM - 8:12AM |
A20.00001: Extracting the LiV3O8 Phase diagram by cluster expansion Tonghu Jiang, Michael Falk LiV3O8 as a lithium battery cathode material has many advantages over current commercialized counterparts, which has prompted interest in improving its electrochemical behavior. However, no clear picture of its structural chemistry and phase behavior has emerged from experimental investigations. In the current work, LiV3O8 was studied using computational methods. A cluster expansion was constructed based on energetic data from density functional theory calculation. The CE was employed to reveal structural information regarding this material. DFT calculation using the local density approximation were found to be deficient in correctly predicting ground states leading to mismatch between experimental and computational results, while generalized gradient approximation gives closer agreement with experimental data. A tentative phase diagram was obtained with the help of Metropolis Monte Carlo calculations. [Preview Abstract] |
Monday, March 21, 2011 8:12AM - 8:24AM |
A20.00002: Magnetic and spectroscopic characterization of C-LiFePO$_{4}$ nanoparticles for cathode material for Li ion batteries Ambesh Dixit, K. Bazzi, M.B. Sahana, C. Sudakar, M. Nazri, P.P. Vaishnava, V. Naik, V.K. Garg, A.C. Oliveira, G.A. Nazri, R. Naik We synthesized pure and carbon coated LiFePO$_{4}$ nanoparticles (size $\sim $25 nm) by sol-gel technique. All the samples were~characterized~by X-ray diffraction, XPS, SQUID, and Mossbauer spectroscopy measurements. The elemental chemical states for Li 1s, Fe 2p, P 2p, O 1s and C 1s were examined by using XPS for LiFePO$_{4}$ and compared with those of C-LiFePO$_{4}$ material. Temperature dependent magnetic measurements suggest an antiferromagnetic transition $\sim $50 K in both LiFePO$_{4}$ and C-LiFePO$_{4}$ samples. The role of various phases, such as LiFePO$_{4}$ Fe$_{x}$P, $\alpha $-Fe and Fe$_{3}$O$_{4}$ identified by Fe$^{57}$ Mossbauer spectroscopy, will be discussed in relationship with the electrochemical properties of the cathode materials. [Preview Abstract] |
Monday, March 21, 2011 8:24AM - 8:36AM |
A20.00003: First-principles modeling of Li-air battery materials Maxwell Radin, Donald Siegel Of the many possible battery chemistries, the so-called ``Li-air'' system is noteworthy in that its theoretical capacity ($\sim $5 kWh/kg, including mass of oxygen) exceeds that of any electrochemical system. Perhaps more importantly, the simplified composition of its air cathode -- involving only the inlet of oxygen from the atmosphere -- has the potential to provide cost benefits in comparison to the Li-ion systems of today. Although the first rechargeable Li-air battery was demonstrated by Abraham and Jiang 14 years ago, its performance in many dimensions remains poor, and relatively little computational work has been done to elucidate performance-limiting phenomena. This talk will introduce the basic properties and main performance issues associated with Li-air batteries. Opportunities for first-principles modeling to assist in overcoming these obstacles will be highlighted. [Preview Abstract] |
Monday, March 21, 2011 8:36AM - 9:12AM |
A20.00004: Materials Challenges and Opportunities of Lithium-ion Batteries for Electrical Energy Storage Invited Speaker: Electrical energy storage has emerged as a topic of national and global importance with respect to establishing a cleaner environment and reducing the dependence on foreign oil. Batteries are the prime candidates for electrical energy storage. They are the most viable near-term option for vehicle applications and the efficient utilization of intermittent energy sources like solar and wind. Lithium-ion batteries are attractive for these applications as they offer much higher energy density than other rechargeable battery systems. However, the adoption of lithium-ion battery technology for vehicle and stationary storage applications is hampered by high cost, safety concerns, and limitations in energy, power, and cycle life, which are in turn linked to severe materials challenges. This presentation, after providing an overview of the current status, will focus on the physics and chemistry of new materials that can address these challenges. Specifically, it will focus on the design and development of (i) high-capacity, high-voltage layered oxide cathodes, (ii) high-voltage, high-power spinel oxide cathodes, (iii) high-capacity silicate cathodes, and (iv) nano-engineered, high-capacity alloy anodes. With high-voltage cathodes, a critical issue is the instability of the electrolyte in contact with the highly oxidized cathode surface and the formation of solid-electrolyte interfacial (SEI) layers that degrade the performance. Accordingly, surface modification of cathodes with nanostructured materials and self-surface segregation during the synthesis process to suppress SEI layer formation and enhance the energy, power, and cycle life will be emphasized. With the high-capacity alloy anodes, a critical issue is the huge volume change occurring during the charge-discharge process and the consequent poor cycle life. Dispersion of the active alloy nanoparticles in an inactive metal oxide-carbon matrix to mitigate this problem and realize long cycle life will be presented. [Preview Abstract] |
Monday, March 21, 2011 9:12AM - 9:24AM |
A20.00005: Vacancy-driven anisotropic defect distribution in LiFePO$_{4}$ Jaekwang Lee, Wu Zhou, Juan Carlos Idrobo, Stephen Pennycook, Sokrates Pantelides It has been reported that iron cations occupying Li sites (Fe$_{Li})$ in LiFePO$_{4}$ are locally aggregated rather than homogeneously distributed in the lattice.$^{1}$ Here we report a combination of density-functional calculations, statistical mechanics, electron-energy-loss spectra (EELS) and show the following. There is a strong binding energy between Fe$_{Li }$and a lithium vacancy (V$_{Li})$, leading to clustering of Fe$_{Li}$ along the b-axis, as observed, corresponding to the shortest separation of the Fe$_{Li }$-V$_{Li}$ pair. EELS data find that a small fraction of Fe atoms are Fe$^{3+}$, which can be accounted for in terms V$_{Li}$-Fe$_{Li}$-V$_{Li}$ clusters formed along the b-axis. [Preview Abstract] |
Monday, March 21, 2011 9:24AM - 9:36AM |
A20.00006: Polaron formation and transport in olivine cathode materials Michelle Johannes, Khang Hoang One of the critical factors limiting Li ion battery performance is electronic conduction through the cathode material. In the olivine structure type materials, such as LiFePO$_4$, the parent materials are insulators with a gap of approximately 4 (or more) eV. The withdrawal of an electron results not in a band-type hole state, but rather a localized polaronic state. Transport then occurs via hopping of the polaron through the crystal. The measured electronic conduction in olivine materials depends on the transition metal cation type. In this study, we use density functional theory to compare formation of polarons in olivine materials with different transition metal cations: Mn, Fe, Co, and Ni. We show that the underlying electronic structure of the fully lithiated material (or fully delithiated material) essentially determines whether or not polaron formation is possible in localized $d$-states or whether the holes that result from adding or removing an electron reside in oxygen-derived states. We also investigate the facility of polaronic hopping by calculating the barrier between adjacent polaron sites in each of the four materials. [Preview Abstract] |
Monday, March 21, 2011 9:36AM - 9:48AM |
A20.00007: First-principles studies of native defects in olivine phosphates Khang Hoang, Michelle Johannes Olivine phosphates Li$M$PO$_{4}$ ($M$=Mn, Fe, Co, Ni) are promising candidates for rechargeable Li-ion battery electrodes because of their energy storage capacity and electrochemical and thermal stability. It is known that native defects have strong effects on the performance of olivine phosphates. Yet, the formation and migration of these defects are not fully understood, and we expect that once such understanding has been established, one can envisage a solution for improving the materials' performance. In this talk, we present our first-principles density-functional theory studies of native point defects and defect complexes in Li$M$PO$_{4}$, and discuss the implications of these defects on the performance of the materials. Our results also provide guidelines for obtaining different native defects in experiments. [Preview Abstract] |
Monday, March 21, 2011 9:48AM - 10:00AM |
A20.00008: Electronic structure of lithium borocarbide as a cathode material for a rechargeable Li-ion battery: First-principles calculation Qiang Xu, Chunmei Ban, Anne Dillon, Suhuai Wei, Yufeng Zhao Traditional cathode materials, such as transition-metal oxides, are heavy, expensive, and often not benign. Therefore, alternative materials without transition metal elements are highly desirable in order to design high-capacity Li-ion batteries of light weight and low price. Here we report on potential application of the LiBC compound as cathode materials, in which graphene-like BC sheets are intercalated by Li ions. The crystal structure and properties of LiBC were firstly reported by W\"{o}rle et al. in 1995. Importantly, it was found that the 75{\%} Li ions can be retrieved out of the compound without changing the layered structure. We have performed first-principles calculations based on density functional theory, as implemented in the Vienna Ab-initio Simulation Package. According to our calculation, the layered Li$_{x}$BC structure can be well preserved at x $>$ 0.5. The reversible electrochemical reaction, LiBC $\leftrightarrow $ Li$_{0.5}$BC + 0.5Li, gives an energy capacity of 609mAh/g and an open-circuit voltage of 2.42V. The volume change is only about 5{\%} during the charging and discharging process. All these results point to a potentially promising application of LiBC as a novel cathode material for high-capacity Li-ion batteries in replacement of the transition metal oxides. [Preview Abstract] |
Monday, March 21, 2011 10:00AM - 10:12AM |
A20.00009: Competing stability of inverse and normal spinel structures for lithium battery cathodes Jishnu Bhattacharya, Christopher Wolverton Transition metal oxides comprise of an important class of cathode materials in rechargeable lithium ion batteries. Many of these materials occur in the spinel crystal structure, in which metal atoms are present in octahedral and tetrahedral interstices of a close-packed oxygen sublattice. Depending on whether the Li or the transition metal ions are found in the tetrahedral sites, one can form either the ``normal'' or ``inverse'' spinel structures. In the present study, we calculate from first principles the relative stability of the inverse vs. normal spinel for a series of transition metal oxides both at lithiated and delithiated limits. We find trends in the stability of the normal vs. inverse spinel are a strong function of lithium content, and explain these results in terms of the preference for metal/Li tetrahedral/octahedral coordination. Despite the similarities between these two structures, they can have a profound effect on the Li diffusivity. We also use our framework to address the stability of multicomponent inverse spinel electrodes, such as LiNiVO$_{4}$. [Preview Abstract] |
Monday, March 21, 2011 10:12AM - 10:24AM |
A20.00010: Atomistic Simulation Study of Lithium Manganese Oxides for Li-Ion Batteries Phuti Ngoepe, Kenneth Kgatwane, Rapela Maphanga, Thi Sayle, Dean Sayle Simulated amorphisation recrystallisation (A+R) technique has been successfully used to generate models of various nano-forms of the complex manganese dioxides [1]. We apply the method to study lithium insertion into the nano - spheres, sheets, rods and porous structures of the binary MnO$_{2}$. The variation of mechanical properties and microstructural features with lithium concentration are investigated. The bulk ternary Li$_{2}$MnO$_{3}$ provides structural integrity for lithium-ion battery cathodes and is electrochemically inactive. The nanocrystalline Li$_{2}$MnO$_{3}$ has a structure similar to that of the bulk, but shows different lithium intercalation properties [2]. We simulated such a nanophase by the A+R method, and the resulting microstructures provide insights into the origins of the electrochemical activity which renders it suitable for battery electrodes. \\[4pt] [1]. T.X.T. Sayle, R.R. Maphanga, P.E. Ngoepe, and D.C. Sayle, J. Am. Chem. Soc., 131, 6161, (2009).\\[0pt] [2]. G. Jain, J. Yang, M. Balasubramanian and J,J. Xu, Chem. Mater. \textbf{17}, 3850, (2005) [Preview Abstract] |
Monday, March 21, 2011 10:24AM - 10:36AM |
A20.00011: Computer modeling of crystalline electrolytes -- lithium thiophosphates and phosphates Nicholas Lepley, N.A.W. Holzwarth During the last 5 years, lithium thiophosphate solid electrolyte materials have been developed\footnote{H. Yamane, M. Shibata, Y. Shimane, et al., {\em{Solid State Ionics}} {\bf{178}}, 1162-1167 (2007).} for use in all-solid-state rechargeable batteries. In particular, crystalline Li$_7$P$_3$S$_{11}$ has been characterized as a superionic conducting material having room temperature conductivities as high as 10$^{-3}$ S/cm, which is 1000 times greater than that of the commercial solid electrolyte material LiPON. Building on our previous work,\footnote{N. A. W. Holzwarth, N. D. Lepley, Y. A. Du, {\em{J. Power Sources}} (2010) [in press: doi:10.1016/j.jpowsour.2010.08.042]} we report computer modeling studies of this material as well as those of related phosphates and phosphonitrides. We present results on meta-stable crystal structures, formation energies, and mechanisms of Li ion migration. The calculational methods are based on density functional theory. The calculations were carried out using the Quantum Espresso (PWSCF) package.\footnote{P. Giannozzi, S. Baroni, et al., {\em{J. Phys.: Condens. Matter.}} {\bf{21}}, 394402 (2009); available from the website: http://www.pwscf.org/.} [Preview Abstract] |
Monday, March 21, 2011 10:36AM - 10:48AM |
A20.00012: Effect of electrolytes on the evolution of the solid electrolyte interphase (SEI) in Li-ion batteries: a Molecular Dynamics study Sang-Pil Kim, Vivek Shenoy Controlling and understanding the atomic level reactions at the interface between electrode and electrolyte is a prerequisite for the improvement of the performance of Li-ion batteries. The solid electrolyte interphase (SEI), which forms on the negative electrode of Li-ion batteries, is known to significantly affect the battery performance leading to irreversible charge loss, exfoliation of graphite anode and affecting the safety. In spite of the large body of work on SEI, a quantitative understanding of the mechanisms of SEI formation is currently not available. In this work, we employ molecular dynamics simulations with reactive force fields to investigate the compositional and structural properties of the SEI. Our simulations capture the mechanisms of SEI formation as Li atoms react with different kinds of electrolytes (ethylene carbonate (EC), dimethyl carbonate (DMC), and their mixtures) and are able to quantitatively predict the properties in terms of the SEI thickness, byproducts, charge loss, and rigidity. [Preview Abstract] |
Monday, March 21, 2011 10:48AM - 11:00AM |
A20.00013: Properties of Liquid Electrolytes for Li-ion Battery Applications from First Principles Molecular Dynamics Simulation Paul Kent, Panchapakesan Ganesh, Deen Jiang A judicious choice of the liquid electrolytes used in battery systems is required to achieve a good balance between high energy storage, fast charging and long lifetime. Ethylene-carbonate (EC) and propylene-carbonate (PC) are popular electrolytes used for this purpose. To date, molecular-dynamics simulations typically rely on classical force-fields, which do not capture the true quantum-mechanical nature of the electrons, most important for the charging/discharging dynamics. We perform accurate first principles molecular-dynamics simulations of EC and PC with LiPF$_6$ at experimental concentrations to build solvation models which explain available Neutron and NMR results as well as to compute Li-ion solvation energies and diffusion constants. Our results throw light on why EC is a more popular choice for battery applications over PC. Insights into the formation of solid-electrolyte interphases in the presence of carbon electrodes in conventional Li-ion batteries will also be discussed, and perspectives into the likely future scope of these simulation methods presented. Supported by the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences under Award Number ERKCC61. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700