Micro-Macroscopic Modeling of a Lithium-Ion Cell By Considering Grain Boundaries of Active Materials

Abstract

Many important properties of electrode materials are profoundly sensitive to deviations from the crystalline perfection. Among them are grain boundaries that play an important role on battery performance by changing the ions distribution inside particles and corresponding stress level change. This paper explores the mechanical and microstructural aspect of battery behavior by developing a cell-level model that incorporates grain boundary diffusion in the electrode particles for the anode and cathode electrodes. The developed model is compared against the grainless model at various operating conditions to understand how grain boundaries influence capacity and stress generation. The results show an appreciable effect of grain boundary diffusion on the voltage profile for the cell for the parameters tested and, overall, a significant reduction in the maximum induced stress experienced in the cell. Stress behavior between the anode and cathode differ significantly, and show that the effective diffusivity of a particle might matter much more significantly than its location in the cell.