A Li-Al-O Solid-State Electrolyte with High Ionic Conductivity and Good Capability to Protect Li Anode

Using a solid-state electrolyte (SSE) to stabilize the Li metal anode is widely considered a promising route to develop next-generation high energy density lithium batteries. Here, a new polycrystalline aluminate-based SSE (named Li-Al-O SSE) with good capability is introduced to protect Li metal. The SSE is formed on the Li metal surface via a chemical reaction between LiOH and triethylaluminum (TEAL) with the existence of LiTFSI-based electrolyte. It is a continuous film that consists of polycrystalline LiAlO2, Li3AlO3, Al2O3, Li2CO3, LiF, and some organic compounds. Such Li-Al-O SSE possesses a room-temperature ionic conductivity as high as 1.42 x 10(-4) S cm(-1). Meanwhile, it effectively protects the Li anode from the corrosion of H2O, O-2, and organic solvent, and suppresses the growth of Li dendrite. With the protection of the Li-Al-O SSE, the cycle life of Li|Li symmetric cell and Li|O-2 cell is substantially elongated, indicating that the SSE exhibits an excellent protective effect under both inert and oxidizing circumstances.