Stabilizing Li7P3S11/lithium metal anode interface by in-situ bifunctional composite layer

All-solid-state lithium metal batteries (ASSLMBs) are well known as the most promising high-energy-density storage systems. However, the unstable interface between sulfide solid electrolyte and lithium (Li) metal anode limits the application of lithium metal in sulfide-based ASSLMBs. Herein, the bifunctional Li3Bi-LiBr protective layer is constructed via a simple in-situ reaction between BiBr3 and lithium metal to solve the instability issue of the Li7P3S11/lithium interface. The merits of the Li3Bi-LiBr protective layer reflect in the low surface barriers of Li3Bi and the high interface energy of LiBr by density functional theory (DFT) calculations. The combination of both can effectively promote lithium diffusion and avoid lithium aggregation, thus inhibiting the growth of lithium dendrite. Results show that the Li-LBB/Li7P3S11/LBB-Li symmetric battery exhibits dramatically increased critical current density (0.838 mA/cm2) and long cycling lifespan (over 2000 h at 0.1 mA/cm2 and 0.5 mAh/cm2) at room temperature. In addition, a distinct capacity retention enhancement about 19.03% is embodied in the LiNbO3@LiCoO2 /Li7P3S11/LBB-Li full cell.