LiAlO₂ Modified Lithium Metal for Li₁₀ GeP₂ S₁₂-Based All-Solid-State Lithium Batteries

Lithium metal is a promising negative electrode material that has received extensive attention owing to its ultrahigh theoretical specific capacity (3860 mAh g⁻¹) and extremely low standard electrode potential (−3.04 V vs standard hydrogen electrode). However, the formation of lithium dendrite and the unstable interface between solid electrolyte and lithium metal have hindered the application of lithium metal in sulfide-based all-solid-state batteries. In this work, a LiAlO₂ interface layer is coated on the surface of lithium metal through magnetic sputtering method. As LiAlO₂ can function as a good Li-ion conductor but an electronic insulator, the LiAlO₂ interface layer can effectively suppress the severe interface reaction between lithium metal and the Li₁₀GeP₂S₁₂ solid electrolyte. The Li@LiAlO₂/Li₁₀GeP₂S₁₂/Li@LiAlO₂ symmetric cell was stably cycled for 3000 h with a low overpotential of 200 mV at 0.1 mA cm⁻² and 0.1 mAh cm⁻². Moreover, unlike the rapid capacity decay of the Li/Li₁₀GeP₂S₁₂/LiCoO₂@LiNbO₃ full cell, the Li@LiAlO₂/Li₁₀GeP₂S₁₂/LiCoO₂@LiNbO₃ full cell remained stable for 96 cycles with a high reversible capacity of 115 mAh g⁻¹.