Diffusion induced thermal effect and stress in layered Li(Ni_0.6Mn_0.2Co_0.2)O₂ cathode materials for button lithium-ion battery electrode plates

Abstract

This paper develops a coupling model of the relationship between chemical reaction, temperature and stress/strain for Li (Ni0.6Mn0.2Co0.2) O2 cathode materials. With the process of reaction, the concentration of electrolyte salt changes rapidly at the beginning of diffusion and tends to dynamic equilibrium. The concentration of electrolyte LiPF6 in electrode materials diffuses from bottom to top with the process of lithium intercalation. In the process of Li-ion intercalation, the temperature rise of porous electrode materials increases sharply at first, then decreases and then increases slowly. The rate of temperature rise in the cathode material increases with the temperature decreases. The volume of electrode material deformed with the expansion along the X-axis and the radial bending along the Y-axis. And the law of stress variation with time is consistent with the temperature-time curve. By the stress-strain distribution nephogram, it is found that the position where the maximum stress is located at the edge of the upper surface, and which is most vulnerable to failure.