LiAlO₂-Modified Li Negative Electrode with Li₁₀GeP₂S₁₂ Electrolytes for Stable All-Solid-State Lithium Batteries

Lithium (Li) metal has an ultrahigh specific capacity in theory with an extremely negative potential (versus hydrogen), receiving extensive attention as a negative electrode material in batteries. However, the formation of Li dendrites and unstable interfaces due to the direct Li metal reaction with solid sulfide-based electrolytes hinders the application of lithium metal in all-solid-state batteries. In this work, we report the successful fabrication of a LiAlO₂ interfacial layer on a Li/Li₁₀GeP₂S₁₂ interface through magnetic sputtering. As LiAlO₂ can be a good Li⁺ ion conductor but an electronic insulator, the LiAlO₂ interface layer can effectively suppress Li dendrite growth and the severe interface reaction between Li and Li₁₀GeP₂S₁₂. The Li@LiAlO₂ 200 nm/Li₁₀GeP₂S₁₂/Li@LiAlO₂ 200 nm symmetric cell can remain stable for 3000 h at 0.1 mA cm^-2 under 0.1 mAh cm^-2. Moreover, unlike the rapid capacity decay of a cell with a pristine lithium negative electrode, the Li@LiAlO₂ 200 nm/Li₁₀GeP₂S₁₂/LiCoO₂@LiNbO₃ cell delivers a reversible capacity of 118 mAh g^-1 and a high energy efficiency of 96.6% after 50 cycles. Even at 1.0 C, the cell with the Li@LiAlO₂ 200 nm electrode can retain 95% of its initial capacity after 800 cycles.