Multi-Scale Simulation of Heterogeneous Surface Film Growth Mechanisms in Lithium-Ion Batteries

A quantitative description of the formation process of the solid electrolyte interface (SEI) on graphite electrodes requires the description of heterogeneous surface film growth mechanisms and continuum models. This article presents such an approach, which uses multi-scale modeling techniques to investigate multi-scale effects of the surface film growth. The model dynamically couples a macroscopic battery model with a kinetic Monte Carlo algorithm. The latter allows the study of atomistic surface reactions and heterogeneous surface film growth. The capability of this model is illustrated on an example using the common ethylene carbonate-based electrolyte in contact with a graphite electrode that features different particle radii. In this model, the atomistic configuration of the surface film structure impacts reactivity of the surface and thus the macroscopic reaction balances. The macroscopic properties impact surface current densities and overpotentials and thus surface film growth. The potential slope and charge consumption in graphite electrodes during the formation process qualitatively agrees with reported experimental results.