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

Abstract

Abstract The high energy density and stability of solid‐state lithium metal batteries (SSLMBs) have garnered great attention. Garnet‐type oxides, especially Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (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–SnF 2 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 Ω·cm 2 ) and high critical current density (1.3 mA·cm −2 ) at 25 °C. The full SSLMB based on LiFePO 4 or LiNi 0.5 Co 0.2 Mn 0.3 O 2 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.