Mesoporous Polyimide Thin Films as Dendrite-Suppressing Separators for Lithium–Metal Batteries

Lithium–metal batteries require the effective suppression of lithium dendrites to guarantee both high performance and safety. Today's separators have macropores allowing lithium dendrites to traverse, leading to internal short circuits and other catastrophic results. Herein, we report a mesoporous polyimide separator for dendrite suppression. The polyimide separator exhibits mesopores of 21 nm width and a high storage modulus of 1.80 GPa. This mesoporous polyimide separator assists in the electrodeposition to form flat-top protrusions instead of sharp dendrites, therefore, allowing the safe cycling of lithium–metal batteries. This work is expected to advance the development of dendrite-suppressing strategies and contribute to the revival of lithium–metal batteries.