Bifunctional polyvinylpyrrolidone generates sulfur-rich copolymer and acts as ?residence? of polysulfide for advanced lithium-sulfur battery

Sulfur-rich copolymer is considered as a promising cathode in lithium-sulfur battery due to its superior chemical confinement for polysulfides on the molecular level, but the sulfur-rich copolymer with low cost and physiological inert is reported rarely. Here, a novel sulfur-polyvinylpyrrolidone (PVPS) copolymer is synthesized by one-step thermal polymerization. The break and recombination of C??O lead to the formation of PVPS, which is proved by various characterizations. Due to the strong chemical confinement of C?S bond, the excellent polysulfides adsorption ability of PVP with abundant polar bonds (such as C?O and C?N) and the improved charge transfer of PVPS, 20PVPS combining with PVP-modified separator as ?residence? of polysulfides delivers the high reversible capacity of 1079 and 729 mAh g-1 at 0.1 and 2 C and a slow capacity fading rate of 0.093% over 500 cycles at 1 C. These findings provide a reference for the synthesis of low-cost, biocompatible and highperformance sulfur-rich copolymer in lithium-sulfur battery.

Automated summary

A novel sulfur-polyvinylpyrrolidone copolymer with excellent polysulfides adsorption ability and improved charge transfer characteristics was synthesized and applied in lithium-sulfur batteries, achieving high reversible capacity and low capacity fading rate.