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Monday, June 17

Computational Design and Modeling of Rechargeable Li-Air Battery Materials

Vyacheslav S. Bryantsev, Liox Power Inc., Pasadena, Calif.
Chemical Sciences Division Seminar
1:00 PM — 2:00 PM, Chemical and Material Sciences Building (4100) Room J-302
Contact: Ben Hay (haybp@ornl.gov), 865.574.6717

Abstract

Demand for better electric vehicles motivates the search for lower cost, higher capacity rechargeable batteries. The successful development of the rechargeable organic electrolyte lithium-air battery, which has received worldwide attention due to very high theoretical gravimetric energy density, is heavily dependent on the long-term stability of major cell components. Design of electrolyte materials that are stable in the operating environment of the air electrode is one of the critical challenges associated with this technology. In this seminar, I will present an overview of our research efforts directed towards identifying stable electrolyte compositions for Li-air systems from quantum chemical calculations. An integrated computational approach is developed that addresses different aspects of solvents stability in the air and lithium electrodes, including the susceptibility to nucleophilic substitution and proton abstraction by superoxide, autoxidation in the presence of molecular oxygen, and the ability to form a stable solid-electrolyte interphase on lithium metal. Combined with experimental methods of characterization of solvent stability, this provides a powerful platform for identifying and designing suitable electrolyte solvents for rechargeable Li-air batteries. Solvent stability is a necessary, but not a sufficient condition for highly reversible formation/decomposition of Li2O2 at the cathode on cycling. I will also present a theoretical approach for predicting the solvation free energies of ionic species in organic solvents. Explicit consideration of the most important solute-solvent interactions combined with accurate gas-phase calculations can provide reliable description of complexation free energies, redox potentials, and other equilibrium properties of charged or highly ionic solutes in organic solvents, which is important to advance our mechanistic understanding of Li-O2 electrochemistry and develop effective separation technologies.