A Multi-Scale Heterogeneous Electrochemical-Diffusion-Induced Stress Coupling Model for Lithium-Ion Batteries

Abstract

During repeated charge/discharge cycles of lithium-ion batteries, diffusion-induced stress (DIS) is generated inside the active particles. For models that neglect the DIS, the simulation accuracy is reduced at high rates. In this work, the cause of the DIS inside the active particles of different size is analyzed, the active material is represented by several particles of different sizes that reference the real particle size distribution of electrode material, and the concentration distribution and DIS are considered for modeling. The solid-phase surface stoichiometric numbers of electrodes are theoretically derived at micro scale by using a parabola equation approximation method, and the basic working process, reactive polarization, concentration polarization, ohmic polarization and other internal processes of the battery are analyzed theoretically and derived at meso and macro scales. Thus, a multi-scale heterogeneous electrochemical-diffusion-induced stress coupling model is built and it is verified based on the test data of LiNi0.6Co0.2Mn0.2O2 battery at different discharge rates. The results show that the model has high accuracy at high rates and can simulate stress and strain inside the electrode materials. The model can carry out rapid iterative solution and provide a foundation for battery management and material development.