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.