Conductive V2O3 electrocatalyst on carbon hollow spheres to accelerate polysulfide conversion for long-cycle and high-rate lithium sulfur batteries

Abstract

The intrinsic very poor electrical conductivity of many transition-metal-oxides is a bottleneck when using them as electrocatalysts in lithium–sulfur (Li–S) batteries. Herein, we report a study using metallic conductive V₂O₃, which is dispersed on carbon hollow spheres, as the electrocatalyst to improve the kinetics of LiPS conversion. Our experimental measurements and theoretical calculations revealed that conductive V₂O₃ exhibits strong interactions with LiPSs, enhancing their adsorption and conversion, while carbon hollow spheres can compensate for the poor conductivity of sulfur and inhibit sulfur's volume expansion. With a sulfur loading of 75%, the V₂O₃/C-HS@S cathode exhibits a high initial discharge specific capacity of 1153 mA h g⁻¹ at 0.05C, remaining at 433 mA h g⁻¹ after 300 cycles at 0.2C, with a capacity retention rate of 99.67%. Even at 2C after 300 cycles, the battery still retains a specific capacity of 298 mA h g⁻¹. This work demonstrates the potential of using a conductive V₂O₃ electrocatalyst dispersed on carbon hollow spheres as a sulfur host in improving the long-cycle life and high-rate performance of Li–S batteries.