Electrochemical-Mechanical Coupled Model for Macro-Scale Stress Prediction of Nickel-Rich NCM Cathodes in Li-ion Batteries†

Abstract

Ni-rich LiNi_xCo_yMn_zO₂ (NCM) materials are regarded as one of the most promising candidates for next-generation lithium-ion batteries due to their high specific capacity. However, their mechanical degradation during cycling leads to significant capacity fading. Electrochemical–mechanical coupled modeling is an effective strategy for understanding the underlying mechanisms of mechanical degradation. Nevertheless, studies involving the simulation and experimental validation of macroscopic electrode stress remain insufficient. This work delineates the multi-scale lithiation-induced strain process in NCM materials and establishes a three-dimensional heterogeneous electrochemical-mechanical coupled model that successfully predicts the macroscopic stress evolution in NCM811 electrodes. Sufficient physical justification and experimental validation are provided for the isotropic simplification of anisotropic single-crystal particles. The simulations reveal the rate performance of particles across different sizes, identifying potential locations of mechanical failure. These findings underscore the importance of macroscopic stress signals in reflecting the electrochemical state of electrodes and provide a validated tool for analyzing battery behavior based on stress information.