Long‐Life All‐Solid‐State Batteries Enabled by Cold‐Pressed Garnet Composite Electrolytes with Enhanced Li+ Conduction

Garnet Li7La3Zr2O12 (LLZO)‐based solid‐state electrolytes (SSEs) hold promise for realizing next‐generation lithium metal batteries with high energy density. However, the high stiffness of high‐temperature sintered LLZO makes it brittle and susceptible to strain during the fabrication of solid‐state batteries. Cold‐pressed LLZO exhibits improved ductility but suffers from insufficient Li+ conductivity. Here, we report cold‐pressed Ta‐doped LLZO (Ta‐LZ) particles integrated with ductile Li6PS5Cl (LPSC) via a Li+ conductive Li‐containing Ta‐Cl structure. This configuration creates a continuous Li+ conduction network by enhancing the Li+ exchange at the Ta‐LZ/LPSC interface. The resulting Ta‐LZ/LPSC SSE exhibits Li+ conductivity of 4.42 × 10–4 S cm–1 and a low activation energy of 0.31 eV. Li symmetric cells with Ta‐LZ/LPSC SSE demonstrate excellent Li dendrite suppression ability, with an improved critical current density of 5.0 mA cm−2 and a prolonged cycle life exceeding 600 h at 1 mA cm‐2. Our finding provides valuable insights into developing cold‐pressed ceramic powder electrolytes for high‐performance all‐solid‐state batteries.