Vanadium nitride/reduced graphene oxide composite interlayer with dual lithium-polysulfide adsorption effect for lithium-sulfur batteries

Abstract

Lithium-sulfur batteries (LSBs) have been developed as next-generation power sources owing to their high theoretical capacities and energy densities, cost effectiveness, and abundance. However, the low electrical conductivity of sulfur in the cathode and the dissolution of lithium polysulfides (LiPS) into the liquid electrolyte are challenging issues that deteriorate both capacity and energy density. Herein, a porous va-nadium nitride and reduced graphene oxide (VN/rGO) composite is prepared as an LSB interlayer that enhances conversion and redox reactions and increases sulfur utilization. Polar VN in the VN/rGO interlayer chemically adsorbs LiPS while rGO provides excellent electrical conduction and a high specific surface area for the physical adsorption of LiPS. The dual LiPS adsorption effect of VN/rGO suppresses shuttle effect and enhances electrochemical performance, leading to specific capacities of 1025 and 693 mA h g-1 at 0.5 and 2 C, respectively, and a retention of 81 % at 0.5 C after 200 cycles.& COPY; 2023 Elsevier B.V. All rights reserved.