Decoding Internal Stress‐Induced Micro‐Short Circuit Events in Sulfide‐Based All‐Solid‐State Li‐Metal Batteries via Operando Pressure Measurements

Abstract Despite the relatively low stiffness of sulfide solid‐state electrolytes (SSEs), which makes them capable of better formability and accommodation for volume changes of active materials, the low fracture toughness ( K IC ) indicates a high susceptibility to fracture caused by electrochemo‐mechanical stresses. This susceptibility to mechanical damages and the subsequent lithium filament penetration, manifesting as micro‐short circuit events, seriously hinders the practical application of lithium metal in high‐energy‐density sulfide‐based all‐solid‐state lithium metal batteries (ASSLMBs). A full understanding of the stress evolution of Li metal anodes during cycling is key to decoding the mechanical damage‐induced micro‐short circuit behavior. Here, an operando and quantitative measurement of the stress evolution of an LTO/SSE/Li configuration all‐solid‐state battery (ASSB) operating with various parameters, including cell capacity and current density, is shown. Two micro‐short circuit modes and their corresponding mechanisms are revealed based on the electrochemo‐mechanical response of the Li metal anode. Furthermore, a finite element model (FEM) is used to explain this mechanical failure and a ′safety zone″ for the Li metal anode related to the ′internal stress″ is given. These findings provide new insight into the micro‐short circuit events induced by electrochemo‐mechanical damage in sulfide‐based ASSLMBs.