Efficient synthesis of graphene/sulfur nanocomposites with high sulfur content and their application as cathodes for Li–S batteries

Abstract

To efficiently realize high sulfur content on a carbon host is of vital importance to boost the performance of Li–S batteries. In this work, a dual-oxidation strategy of H₂S is designed to synthesize graphene/sulfur composites with a sulfur content as high as 80 wt%. In particular, H₂S is bubbled into the aqueous dispersion of graphene oxide (GO) containing H₂O₂, during which sulfur is generated through the dual oxidation of H₂S by H₂O₂ and GO. Interestingly, the as-formed sulfur is amorphous and strongly anchored on the graphene nanosheets. Benefiting from the structural merits, the graphene/sulfur nanocomposite affords a high specific capacity of 680 mA h g⁻¹ based on the total mass of the nanocomposite at a current density of 0.2 A g⁻¹ and good cycle performance with 85% of capacity retained at 0.5, 1.0 and 5.0 A g⁻¹ after 100 cycles. Besides efficiently producing a high-performance cathode for Li–S batteries, the method developed here also offers great promise for pollutant control.