A lithium-tin fluoride anode enabled by ionic/electronic conductive paths for garnet-based solid-state lithium metal batteries

The high energy density and stability of solid-state lithium metal batteries (SSLMBs) have garnered great attention. Garnet-type oxides, especially Li6.4La3Zr1.4Ta0.6O12 (LLZTO), with high ionic conductivity, wide electrochemical window, and stability to Li metal anode, are promising solid-state electrolyte (SSEs) materials for SSLMBs. However, Li/LLZTO interface issues including high interface resistance, inhomogeneous Li deposition, and Li dendrite growth have hindered the practical application of SSLMBs. Herein, a multi-functional Li-SnF2 composite anode with Li, LiF, and Li-Sn alloy was specifically designed and prepared. The composite anode improves the wettability to LLZTO, constructing an intimate contact interface between it and LLZTO. Meanwhile, ionic/electronic conductive paths in situ formed at the interface can effectively uniform Li deposition and suppress Li dendrite. The solid-state symmetric cell exhibits low interface resistance (11 Omega.cm(2)) and high critical current density (1.3 mA.cm(-2)) at 25 degrees C. The full SSLMB based on LiFePO4 or LiNi0.5Co0.2Mn0.3O2 cathode also shows stable cycling performance and high rate capability. This work provides a new composite anode strategy for achieving high-energy density and high-safety SSLMBs.