A robust solid electrolyte interphase layer coated on polyethylene separator surface induced by Ge interlayer for stable Li-metal batteries

Lithium (Li) dendrite growth and poor Coulombic efficiency (CE) lead to a safety issue and inferior electrochemical properties, which are the major obstacles that circumvent high energy density Li metal battery (LMB) development in practical applications. Here, it is demonstrated that the Ge interlayer deposited on commercial polyethylene (PE) separator (Ge@polyethylene, Ge@PE) spontaneously induces the formation of a pleated solid electrolyte interphase (SEI) layer, which can effectively prevent the isolated Li dendrites formation and propagation during cycling. The optimized Ge@PE configuration enables obvious improvement in Li plating/stripping behavior in Li Ge@PE Cu battery due to the robust and efficient SEI layer. Impressively, the Li Ge@PE LCO(LiCoO₂) full battery also endows enhanced electrochemical cyclability and exhibits Li dendrite-free generation during the repeated Li plating/stripping process. Our strategy could open an alternative way to optimize high performance LMB or other efficient Li metal based energy storage systems.