Synergistic improving sulfur reduction reaction by VS4 embedded N-doped carbon fiber composite host towards practicable lithium sulfur batteries

Sluggish reaction kinetics of sulfur reduction reaction as a serious bottleneck hinders the commercialization applications of high energy density LiS batteries. Herein, a multi-functional component is constructed as a polysulfide trapper and catalyzer towards boost the intermediates immobilization and conversion on the side of sulfur cathode. In this composite, VS4 is anchored on the surface of biomass carbon fibers (CF) by in situ growth process, which conducive to rapid charge transfer at interfaces. The cattail-derived CF with boom-like morphology can not only offer the consecutive electron transport pathways for sulfur reaction, but also endow cathode with luxuriant polar N sites for immobilizing polysulfides. Meanwhile, VS4 with a conductive linear-chain structure can effectively anchor polysulfides on the V4+(S22−)2 chains and expedite charge-transfer kinetics. Consequently, the CF/VS4-S cathode by feat of the unique structure and constituent achieves impressive electrochemical performances, including large reversible capacity (1356 mAh g−1 at 0.1C), improved rate capability (750 mAh g−1 at 2C), cycling stability (capacity decline rate of 0.039 % per cycle at 0.2C), and tardy self-discharging behavior (93.3 % of capacity retention after resting for 48 h). The excellent battery performances confirm a potential solution for realizing practical implementation of LiS batteries.