Modeling of contact stress among compound particles in high energy lithium-ion battery

Compared to other high capacity anodes, Silicon (Si) has the highest gravimetric capacity, volumetric capacity, a relatively low discharge voltage and abundant storage on the earth, Si and Si based materials has become more and more popular in battery industries among which Silicon-Carbon (Si-C) core-shell particle has been one of the most promising and commercially feasible candidates to achieve ultrahigh capacity of the anode for lithiumion batteries. Silicon-Carbon (Si-C) core-shell particle has been one of the most promising and commercially feasible candidates to achieve ultrahigh capacity of the anode for lithium-ion batteries. However, most silicon-based anode materials suffer from severe performance deterioration especially during fast charging process. Modeling the mechanical stress and deformation of anode particles is thus of great fundamental and practical interest to understand the mechanism of silicon-carbon anodes. We establish both computational and theoretical methods to describe the stress distribution and contact behaviors within and among Si-C particles, as well as the Li+ diffusion within Si particle. We further analyze the charging rate dependent behavior of the core-shell structure. Our analysis reveals a complete link between stress, charging rate, Li+ diffusion and the structural variables. Our study thus opens a novel pathway to design the structured high-capacity silicon-carbon at nano-scale for expanding Si-based anode application within limited amount beyond cylindrical configuration and increasing the glass ceiling of battery energy density based on graphite anode.