Chemo-mechanical coupling phase-field modeling of lithium dendrite growth within solid electrolyte

Solid-state lithium metal batteries are one of the most promising next-generation high-energy–density storage devices. However, the continuous growth of lithium dendrites could cause internal short circuits, capacity attenuation, and even thermal runaway of the solid-state lithium metal batteries. Though there are some studies on lithium dendrites, the growth mechanism is not yet clear because of a nonlinear system involving many reactions. Here, we propose a chemical–mechanical coupling phase-field model of lithium dendrite growth within solid electrolyte, taking into account not only the electrochemical reaction for dendrite growth, but also the interaction between dendrite and solid electrolyte. This model exhibits the evolutions of the morphology and stress distribution for single and multiple lithium dendrites and the influences of mechanical strength, anisotropic strength, electrode conductivity, and interface mobility coefficient on the lithium dendrite growth. The results show that higher mechanical strength, anisotropic strength, interfacial mobility coefficient, and lower electrical conductivity can inhibit dendrite growth. The mechanical strength and anisotropic strength have a significant effect on the dendrite morphology and stress distribution. In addition, although the secondary growth of multiple dendrites is inhibited, the overall stress is higher than that of single dendrite, which could cause greater solid electrolyte damage. This research can provide theoretical guidance for revealing the fracture mechanism of solid electrolytes and improving the optimal design of solid electrolyte materials.