Nonequilibrium Electron-Coupled Lithium Ion Diffusion in LiFePO4: Nonadiabatic Dynamics with Multistate Trajectory Approach

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• 作者：Guohua Tao
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 7, 2016
• 年：2016
• 卷：120
• 期：13
• 页码：6938-6952
• 全文大小：1341K
• ISSN：1932-7455

文摘

The recently developed multistate trajectory approach is implemented for nonadiabatic molecular dynamics simulations on electron-coupled Li ion diffusion in LiFePO₄, a promising cathode material for lithium ion batteries. The approach is demonstrated to be highly efficient and numerically stable in treating realistic complex molecular systems including tens of electronic states and hundreds of particles and to be capable of providing inspiring molecular pictures via a multistate representation on nonadiabatic quantum dynamics, such as Li ion diffusion and its correlation with electron transport in LiFePO₄. The results from our real time nonequilibrium simulations indicate that the electron-coupled Li ion diffusion is significantly enhanced upon the formation of a small polaron, and nonadiabatic couplings further facilitate Li ion diffusion. Therefore, we suggest that nonequilibrium diffusion and nonadiabatic couplings could also be responsible for the wide range of Li ion diffusion coefficients obtained from various theoretical calculations and experimental measurements. Our findings may aid in the understanding of the molecular mechanisms of Li ion diffusion in LiFePO₄ and design of new cathode materials for lithium ion batteries.