Multiscale Simulations to Study the Atomic Structure of Solid Electrolyte Interfaces

Abstract

The Solid Electrolyte Interface (SEI) is the "most important but least understood" area of research in batteries. A deeper understanding of the atomic structure of SEI can provide a theoretical basis for the development of high energy density batteries. Based on the available experimental results, four generations of SEI models have been developed. However, the above-mentioned SEI models lack atomic details and cannot reasonably explain important experimental phenomena and guide experimental synthesis. Quantum chemistry (QM)-based multi-scale theoretical simulations are a powerful tool to study the atomic structure of interfaces. The authors' group has developed a series of computational methods for SEI simulations in recent years,1 including the Hybrid ab initio molecular dynamics combined with reactive force fields (HAIR)2, the Kinetic Monte Carlo method for simulating lithium dendrite Kinetic Monte Carlo (KMC) method for simulating the growth of lithium dendrites, etc. Applying these methods, we have performed detailed theoretical simulations of the formation of the SEI interface and achieved some milestones, including (1) elucidation of the important initial decomposition reaction mechanism of solute and solvent (Fig. 1a);2 (2) revealing the formation process and structure of the initial inorganic LiF layer of SEI (Fig. 1b);3 (3) resolving the SEI solid-solid phase transition in all-solid-state batteries (Fig. 1b).4 The above theoretical simulation progress provides important theoretical guidance for the development of high energy density and high safety batteries, such as Li-Metal batteries, Li-Sulfur batteries, and all-solid-state batteries. Currently, the Battery open source package developed by the group has implemented most of the above functions.Reference[1] Cheng T; Jaramillo-Botero A; An Q; Ilyin DV; Naserifar S; Goddard WA*;Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 18193.[2] Liu Y; Yu PP; Wu Y; Yang H; Miao X; Huai LY; Goddard WA*; Cheng T*; J. Phys. Chem. Lett. 2021, 12, 1300.[3] Liu Y; Sun QT; Yu PP; Wu Y; Xu L; Yang H; Xie M; Cheng T*; Goddard III WA; J. Phys. Chem. Lett. 2021,12, 2922.[4] Cheng T; Merinov BV*; Morozov S; Goddard WA; ACS Energy Lett. 2017, 2, 1454. Figure 1