Modeling Li-ion concentration distribution and stress of porous electrode particles considering binder and direct particle contact

Abstract

During electrochemical cycling, stresses in porous electrode particles arise primarily due to the development of Li-concentration gradients and direct contact between particles, which cause a deterioration in the performance of Li-ion battery electrodes. A model for simulating the effects of binders and direct contact between particles on the Li-ion concentration and stress distribution of active material (AM) particles is proposed in this work. The Li-ion concentration and contact stress of a unidirectional coupling model and a fully coupled model are compared. The influence of binders and the influence of direct contact between particles on the concentration profile and stress distribution are numerically investigated. The simulations show that the direct contact between particles hindered Li-ion insertion, and its blocking effect was stronger than that of the binder. The compressive stress in the area covered by the binder was much smaller than the compressive stress in the area of direct contact between the AM particles. The binder is most likely to debond at the edge of the particle-binder interface. The developed model and results could lay the foundation for studying the contact-diffusion-stress coupling behavior of porous electrode particles.