Coupled crack propagation and dendrite growth in solid electrolyte of all-solid-state battery

Lithium metal all-solid-state batteries (ASSBs) are promising candidates for future lithium batteries thanks to their high safety performance and energy density. However, Li dendrite growth and interfacial failure are the two fatal issues deteriorating the cyclability that hinders the wide commercialization of ASSBs. To further understand the underlying mechanisms, a coupled electrochemical-mechanical phase-field model for grain crack propagation and lithium dendrite growth is proposed from the energy conservation perspective in this study. We discover that longer defect with sharp edge and angle (θ≥45°) causes more severe crack propagation and leads to larger dendrite growth area due to the increased strain energy density. We observe that the initial defect within grain plays an irrelevant role in the dendrite growth within the grain boundary. Stacking pressure greater than 10 MPa significantly speeds up crack propagation as well as dendrite growth due to the nontrivial mechanical driving force. Mechanical stress-induced strain-energy would contribute to more than 15% of the total dendrite growth once the stacking pressure exceeds 20 MPa, while it is trivial if the stacking pressure is below 10 MPa. Large enough fracture threshold strain can prevent the crack propagation. Results provide a fundamental tool for the design and evaluation of ASSB safety and cyclability from a more comprehensive perspective and clear the barrier for the development of next-generation ASSBs.