Hierarchically Designed CNF/S−Cu/CNF Nonwoven Electrode as Free‐Standing Cathode for Lithium−Sulfur Batteries

A flexible lithium−sulfur (Li−S) battery cathode is prepared through uniformly depositing sulfur solution into an electrospun N‐rich and Cu‐decorated nonwoven carbon nanofiber (CNF) film to form sandwich structured CNF/S−Cu/CNF film electrodes. As a free‐standing cathode of Li−S battery, the unique structural CNF/S−Cu/CNF composite cathodes exhibit high capacity and rate capability as well as long cycling stability. The electrodes can deliver a reversible capacity of 1295 mAh g −1 at a current density of 0.1 A g −1 , and maintain more than 530 mAh g −1 even at a high current rate of 1 A g −1 after 300 cycles along with a Coulombic efficiency close to 100 %. The exceptional performance of CNF/S−Cu/CNF as cathode in Li−S batteries is attributed to a synergistic contribution from the CNF layers, the decorated‐Cu nanoparticles and the doped N element in CNF, which can physically and chemically stabilize S and provide fast electronic conductivity. This facile strategy will pave the way to construct high‐performance flexible Li−S batteries.