Accelerating the Development of LLZO in Solid‐State Batteries Toward Commercialization: A Comprehensive Review

Abstract Solid‐state batteries (SSBs) are under development as high‐priority technologies for safe and energy‐dense next‐generation electrochemical energy storage systems operating over a wide temperature range. Solid‐state electrolytes (SSEs) exhibit high thermal stability and, in some cases, the ability to prevent dendrite growth through a physical barrier, and compatibility with the “holy grail” metallic lithium. These unique advantages of SSEs have spurred significant research interests during the last decade. Garnet‐type SSEs, that is, Li 7 La 3 Zr 2 O 12 (LLZO), are intensively investigated due to their high Li‐ion conductivity and exceptional chemical and electrochemical stability against lithium metal anodes. However, poor interfacial contact with cathode materials, undesirable lithium plating along grain boundaries, and moisture‐induced chemical degradation greatly hinder the practical implementation of LLZO‐based SSEs for SSBs. In this review, the recent advances in synthesis methods, modification strategies, corresponding mechanisms, and applications of garnet‐based SSEs in SSBs are critically summarized. Furthermore, a comprehensive evaluation of the challenges and development trends of LLZO‐based electrolytes in practical applications is presented to accelerate their development for high‐performance SSBs.