Dual Structure-Material Design of Separators toward Dendrite-Free Lithium Metal Anodes.

The practical applications of lithium metal anodes have been severely hindered by the Li dendrite issue. Herein, a dual structure-material design strategy was developed to fabricate a new type of separator using interconnected hollow porous polyacrylonitrile (PAN) nanofibers (HPPANF), which delivered controllable and dendrite-free Li depositions. The interconnected mesopores on HPPANF bridged the hollow interiors with the outside voids among the fibers, enabling outstanding electrolyte uptake capabilities for high ion conductivity, and nano-level wetted electrolyte/anode interface for uniform Li plating/stripping. In parallel, the HPPANF separator enriched with polar groups acted as an exceptional polymer-based solid-state electrolyte, providing 3D ion channels for the transport of Li ions. Benefiting from the dual structure-material design, the HPPANF separator induced uniform Li ion flux for dendrite-free Li depositions, which caused enhanced cycling stability (1300 h, 3 mA cm -2 ). This work demonstrates a new method to stabilize Li metal anodes through rational separator design.