Unlocking the Electrochemical–Mechanical Coupling Behaviors of Dendrite Growth and Crack Propagation in All‐Solid‐State Batteries

Dendrite growth and crack propagation are two major hurdles on the road towards the large‐scale commercialization of lithium metal all‐solid‐state batteries (ASSBs). Due to the high multiphysics coupled nature of the underlying dendrite growth mechanism, understanding it has been difficult. Herein, for the first time, an electrochemical‐mechanical model is established that directly couples dendrite growth and crack propagation from a physics‐based perspective at the cell level. Results reveal that overpotential‐driven stress propels a crack to penetrate through the solid electrolyte, creating vacancies for dendrite growth, leading to the short circuit of the battery. Thus, high lithiation/charging rate and low conductivity of electrolytes can accelerate the electrochemical failure of the battery. It is further discovered that Young's modulus E LLZO of the electrolyte has competing contributions to the fracture and dendrite growth; specifically, when E LLZO = 40–100 GPa, the short circuit is triggered early. A larger toughness value hinders the crack propagation and mitigates the Li dendrite growth. The developed multiphysics model provides an in‐depth understanding of the coupling of crack propagation and dendrite growth within ASSBs and an insightful mechanistic design guidance map for robust and safe ASSB cells.