关键词: 锂离子电池, 多物理场耦合, 电化学-热-力, 能量密度, 有限元仿真, 应力, 粒径, 优化设计

Abstract:

In order to deeply understand the multi-physical field coupling behavior inside the LIB(Lithium-Ion Battery) and better provide reference for the manufacturing and optimization design of the LIB, a more physically realistic coupled ETM(Electrochemical-Thermal-Mechanical) model of the LIB is established and solved in the finite element simulation software COMSOL Multiphysics by means of numerical simulation in the present study. The model takes into account the stress generation in both electrode and particle scales during battery operation, which solves the problem of difficult calculation of stress at the electrode level in previous models, and better correlates the relationship between stress and electrochemistry by considering the correction of stress on lithium diffusion and overpotential. Based on this model, the effect of different positive electrode particle sizes on the battery performance is discussed in the study. The numerical results show that the performance index of each physical field during the discharge of LIB is better and the energy density of the battery is improved when the positive electrode particle size is small, which proves that the use of smaller positive electrode particle size can improve the performance of LIB.

Key words: lithium-ion battery, multi-physics field coupling, electrochemical-thermal-mechanical, energy density, finite element simulation, stress, particle size, optimal design