Micro-macroscopic modeling of a lithium-ion battery by considering grain boundaries of active materials

Many important properties of electrode materials are profoundly sensitive to deviations from the crys-talline perfection. Among them are grain boundaries, which play an important role on battery perfor-mance by altering the distributions of ions inside the particles and changing the corresponding stress level. This paper explores the mechanical and microstructural aspects of battery behavior by developing a cell-level model that incorporates grain boundary diffusion in the electrode particles for the anode and cathode. The developed model is compared against a grainless model at various operating conditions to understand how grain boundaries influence capacity and stress generation. The results from the model revealed that the location of the maximum stress might not necessarily occur at the separator interface at any given time as the particles with heterogeneous diffusion paths displayed gradual changes in flux profile, which has just been believed in practice. The grain structure geometry variability showed that less diffusive particles at the rear side endure more stress than high diffusive frontal particles. Also, the results show an appreciable effect of grain boundary diffusion on the voltage profile of the cell for the tested parameters and, overall, a significant reduction in the maximum induced stress 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. With heterogeneous particle shape modeling capabilities, this approach can be next-generation battery model that improves under-standing of battery materials and electrodes. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the impact of grain boundaries on battery performance, revealing that grain boundary diffusion significantly affects the voltage profile and maximum stress in the cell. Variability in grain structure geometry results in particles with lower diffusion at the rear side enduring more stress than highly diffusive frontal particles.