High Rate and Stable Solid-State Lithium Metal Batteries Enabled by Electronic and Ionic Mixed Conducting Network Interlayers.

All solid-state lithium (Li) metal batteries (SSLMBs) are attractive for prospective electrochemical energy storage systems on account of their high energy densities and good safeties. However, the incompatible interface between the solid-state electrolyte and Li metal anode limits the ability of SSLMBs. Here, a three-dimensional (3D) electronic and ionic mixed conducting interlayer is proposed to improve the interfacial affinity in SSLMBs. The 3D electronic and ionic mixed conducting interlayer is composed of a Sn/Ni alloy layer-coated Cu nanowire (Cu@SnNi) network. The Li plating demonstrates that the Cu@SnNi network can possess fast Li+ ion transport channels from the Li metal to LiFePO4, acting as a stable interlayer between the Li metal and solid polymer electrolyte. Noticeably, the solid-state LiFePO4/Li cell with a Cu@SnNi interlayer exhibits an excellent rate capability (133 mA h g-1, 2 C; 100 mA h g-1, 5 C) in comparison to the low rate performance of the cell without the interlayer (117 mA h g-1, 2 C; 60 mA h g-1, 5 C). This unique structure design of electronic and ionic mixed conducting interlayer provides an alternative strategy to improve the performance of SSLMBs.