Enhanced Electrochemical Performance of Lithium–Sulfur Batteries with Surface Copolymerization of Cathode

Abstract

© The Author(s) 2019. Lithium-sulfur batteries with high specific capacity, low-cost, and environmental benignity show great potential for advanced energy storage systems. However, the poor conductivity of elemental sulfur, the shuttle effect and the uncontrollable deposition of lithium sulfides species result in poor cycling stability and low Coulombic efficiency. Despite the recent success in trapping soluble polysulfides via porous matrix and chemical binding, considerable weight of cathode is occupied by the conductive additives. Herein, we discovered that copolymerization of sulfur on the surface of cathode with 1,3-diisopropenylbenzene is highly effective to bind with sulfur species. Compared with bare traditional cathode, the cathode covered with vulcanized poly(sulfur-random-1,3diisopropenylbenzene) exhibit remarkable capacity retention (916.6 mAh g−1 after 100 cycles at 0.2C). It delivers high specific capacities at higher C-rates (up to 400 mAh g−1 at 2C). The superior electrochemical properties with high sulfur utilization ratio could be attributed to the protective effect of surface modification with poly(sulfur-random-1,3-diisopropenylbenzene).