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.
Keywords LiAlO2,lithium metal,Li10GeP2S12,interface modification,magnetic sputtering,all-solid-state batteries