Elastoplastic model for chemo-mechanical behavior of porous electrodes using image-based microstructure

The microstructure of electrodes is intrinsically complex and thus should be determined prior to the analysis of the chemo-mechanical performance during charge/discharge cycles. In this study, a microstructurally resolved, fully coupled chemo-mechanical model was developed to investigate the structure–property relationship of electrodes in the framework of elastoplastic finite deformation. The active particles, binder, and pores of real electrode images were segmented and reconstructed using the region-growing method. The effects of the electrode microstructure on the diffusion-induced stress (DIS) distribution, local electric potential and electrical resistance, interaction between the binder and particles, and mechanical failure of the particle–binder interface (PBI) were elucidated considering the finite concentration effect, concentration-dependent modulus and yield strength. The results indicate that the microstructure of electrodes significantly influences the distribution of DIS, local electric potential, and electrical resistance. The elastoplastic finite deformation theory can accurately describe the stress singularities that occur near sharply concave regions. Additionally, the use of a relatively soft binder was found to accommodate the expansion of active particles and mitigate the effects of particle interaction. Furthermore, being able to ensure that the active particles maintain a simple convex shape can reduce the likelihood of particle pulverization and PBI debonding. These results will enhance the understanding of the evolution of stress generation, the local electric potential and electrical resistance, and the mechanical failure of the PBI within the microstructure of porous electrodes; the results also emphasize the need for an optimized microstructure design for porous electrodes.

https://www.sciencedirect.com/science/article/pii/S0020768322003675