Simulations of dendrite and crack and their interactions in solid electrolyte by phase field method

In solid state lithium batteries, lithium dendrites are prone to nucleate and grow at unstable electrode/electrolyte interfaces, intergranular and internal defect sites, which may cause damage to electrolyte structure and reduce battery capacity. Aiming at the problem of lithium dendrite growth in solid electrolytes, a mechanical-electrical-chemical coupling phase field model is proposed by introducing phase field variables and damage variables. The interaction between dendrites and electrolytes, as well as the correlation between dendrite growth and crack evolution are explored. The results indicate that the dendrites contract internally under the action of electrolytes and their growth is inhibited, and the higher the mechanical strength of electrolytes, the more obvious the inhibition effect. The electrolytes could suffer cracks and expands under the action of dendrites, leading to material failure. What's more, dendrites growth is always consistent with crack propagation morphology, and the slower dendrites grow, the fuller they fill the crack space, and the greater the interaction force with electrolytes. This study can provide theoretical guidance for revealing the damage mechanism of solid electrolytes and improving the optimization design of solid electrolyte materials.