A Lithium Intrusion‐Blocking Interfacial Shield for Wide‐Pressure‐Range Solid‐State Lithium Metal Batteries

Abstract Lithium garnets are considered as promising solid‐state electrolytes for next‐generation solid‐state Li metal batteries (SSLBs). However, the Li intrusion driven by external stack pressure triggers premature of Li metal batteries. Herein, for the first time, an in situ constructed interfacial shield is reported to efficiently inhibit the pressure‐induced Li intrusion in SSLBs. Theoretical modeling and experimental investigations reveal that high‐hardness metallic Mo nanocrystals inside the shield effectively suppress Li dendrite growth without alloy hardening‐derived interfacial contact deterioration. Meanwhile the electrically insulated Li₂S as a shield component considerably promotes interfacial wettability and hinders Li dendrite penetration into the bulk of garnet electrolyte. Interfacial shield‐protected Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO)‐based cells exhibit significantly enhanced cyclability without short circuits under conventional pressures of ≈0.2 MPa and even at high pressure of up to 70 MPa; which is the highest endurable stack pressure reported for SSLBs using garnet electrolytes. These key findings are expected to promote the wide‐pressure‐range applications of SSLBs.