Coupled diffusion-mechanical analysis with dislocation effect in porous spherical electrode

Abstract

The electrochemical and mechanical performance of lithium-ion batteries is greatly affected by the porous electrode materials and dislocation effect. A diffusion-mechanical coupling model of porous electrode particle with dislocation effect is developed under potentiostatic operation in this work. Then, the distributions of lithium-ion concentration, volumetric strain and stress in the electrode particles with/without dislocation effect are analyzed. Finally, the influences of porosity and tortuosity on the lithium-ion concentration, volumetric strain, radial stress, hoop stress and strain energy are numerically discussed, respectively. The results show that dislocation effect retards the diffusion and relieves the electrode particle expansion and stresses. Moreover, larger porosity or smaller tortuosity can enhance the charge efficiency and avoid electrode particle damage or crack nucleation and propagation by reducing the stress and strain energy. Finally, from the perspective of fracture, dislocation effect can resist the crack propagation or avoid the formation of cracks during charge. This work will provide some theoretical guidance to improve the charge efficiency and prolong battery life.