Lithium storage performance and mechanism of VS4/rGO as an electrode material associated with lithium-sulfur batteries

Nanorod vanadium sulfide anchored on reduced graphene oxide nanosheets composite is prepared by a simple solvothermal method. As an electrode material for lithium-ion batteries, the composite with 13 wt% reduced graphene oxide delivers 1886.3 and 1322.3 mAh g⁻¹ specific capacities for the initial discharge and charge, respectively, resulting in 70.1% of Coulombic efficiency, and has a good capacity retention with 1181.9 mAh g⁻¹ after 50 cycles, much higher than that of pure vanadium sulfide submicrospheres. It exhibits a good cycling stability and an enhanced high-rate capability. Lithium storage mechanism is investigated by cyclic voltammetry, electrochemical impedance spectrum and discharge-charge measurements. The results show that the vanadium sulfide with reduced graphene oxide composite can convert to sulfur + vanadium with reduced graphene oxide composite after the first cycle, and the reduced graphene oxide can effectively inhibit the dissolution of polysulfide while metal vanadium increases electrode electronic conductivity, leading to an enhanced electrochemical performance. The composite is proved to be a promising functional material associated with lithium-sulfur batteries.