Efficient electrochemical energy conversion is one of the great technological challenges of our time. Such processes are critical to facilitating clean, efficient electricity generation via fuel cells as well as for enabling solar and wind energy to become a significant part of our energy portfolio via grid-scale battery storage. As this talk is meant to engage applied mathematicians and computational scientists, the focus will be on discussing two quantum mechanical methods we have been developing for accurate simulations of charge transfer processes at electrode surfaces and for predicting the mechanical response of battery electrode materials during charge-discharge cycles. It is well known that commonly used density functional theory (DFT) approximations do a poor job of describing charge transfer. Our embedded correlated wavefunction (ECW) theory (1) is able to accurately describe, e.g., the first step of the oxygen reduction reaction (ORR) that occurs at fuel cell cathodes, while conventional DFT completely fails (2). Recent advances in orbital-free DFT (OFDFT), a method that scales quasi-linearly with a small prefactor, now furnishes accurate treatment of semiconductor materials (3) and transition metals (4). We have already shown the power of OFDFT for calculating plasticity in metals (5); we aim to do the same for Li intercalation in next-generation silicon anodes for Li ion batteries, where mechanical failure upon cycling must be prevented. (1) C. Huang, M. Pavone, and E. A. Carter, "Quantum mechanical embedding theory based on a unique embedding potential," J. Chem. Phys., 134, 154110 (2011). (2) F. Libisch, C. Huang, P. Liao, M. Pavone, and E. A. Carter, "Origin of the Energy Barrier to Chemical Reactions of O2 on Al(111): Evidence for Charge Transfer, Not Spin Selection," Phys. Rev. Lett., 109, 198303 (2012). (3) J. Xia and E. A. Carter, "Density-Decomposed Orbital-Free Density Functional Theory for Covalently Bonded Molecules and Materials," Phys. Rev. B, 86, 235109 (2012). (4) Y. Ke, F. Libisch, J. Xia, L.-W. Wang, and E. A. Carter, “Angular Momentum Dependent Orbital Free Density Functional Theory,” Phys. Rev. Lett., 111, 066402 (2013). (5) I. Shin and E. A. Carter, “Possible Origin of the Discrepancy in the Peierls Stresses of FCC Metals: First-Principles Simulations of Dislocation Mobility in Aluminum,” Phys. Rev. B, 88, 064106 (2013).
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