Sulfur–hydrazine hydrate-based chemical synthesis of sulfur@graphene composite for lithium–sulfur batteries

Although the melt-diffusion method was applied to fabricate sulfur-based cathode for lithium–sulfur batteries, more efforts should be devoted to the development of synthetic methodology of sulfur-based hybrids. Herein, we report a sulfur–hydrazine hydrate chemistry-based method to prepare the composite of sulfur and N-doped reduced graphene oxide (S@N-rGO) with 76% sulfur content. Relying on the reaction of sulfur and hydrazine hydrate, cyclo-sulfur was broken to form soluble polysulfides. The subsequent refluxing with GO suspension rendered the transformation of soluble polysulfides to sulfur crystal homogeneously deposited on N-rGO due to direct nucleation from solution. Simultaneously, the nitrogen doping of GO was realized with hydrazine hydrate as doping agent in the one-pot route. The as-obtained S@N-rGO composite displayed a good rate capability and excellent capacity stability up to 300 cycles. This study may provide a new and facile method to construct the composite of sulfur and N-doped carbonaceous matrix, which makes the hybrid a competitive cathode material for lithium–sulfur batteries (LSBs).