CoS2-Decorated Cobalt/Nitrogen Co-Doped Carbon Nanofiber Networks as Dual Functional Electrocatalysts for Enhancing Electrochemical Redox Kinetics in Lithium–Sulfur Batteries

Lithium sulfur (Li–S) batteries have been considerably studied in energy storage systems because of their extremely high energy density. Nevertheless, poor sulfur utilization and lower sulfur loading, polysulfides shuttling, and short cycling life are the major obstacles to their application. Herein, we present the cubic structure of CoS2 microcrystals decorated on Co/N-codoped carbon nanofibers (denoted as CSCNC) by an electrospinning technique followed by a hydrothermal process. The Li2S6 catholyte was added in the fibrous CSCNC network as the current free electrode for Li–S batteries, which was used as the positive catalyst to restrain the shuttle effect and facilitate the reaction kinetics. Additionally, CoS2 and Co are dual functional electrocatalysts for facilitating lithium sulfide nucleation onto the surface of CSCNC, thus reduce electrochemical polarization and enhance the specific capacity. This CSCNC@Li2S6 electrode exhibits 877 mAh g–1 capacity retention with sulfur loading of 7.11 mg over 200 cycles and has an average decay of 0.11% per cycle. Additionally, the composite electrode with sulfur loading accomplishes up to 14.22 mg, providing 12.7 mAh of extremely high capacity, which is much higher than that of the carbon-based electrodes for Li–S batteries.