One-step hydrothermal preparation and electrochemical performance of graphene/sulfur cathode composites

Abstract

Reduced graphene oxide/sulfur (RGO/S) composites were synthesized by a one-step hydrothermal method using a mixture of sodium thiosulfate (Na2S2O3) and graphene oxide (GO) solution reacting under acid conditions. We explored the influence of the hydrothermal temperature, reaction time, and sulfur content on the composites. Analysis by X-ray diffraction (XRD), scanning electron microscope (SEM), and the galvanostatic charge and discharge shows that the composites have excellent cycling performance when synthesis occurs at 180 °C for 12 h to provide a carbon:sulfur mass ratio of 3:7. The first discharge capacity is delivered at 931 mAh{bullet operator}g-1 and it remains at 828.16 mAh{bullet operator}g-1 after 50 cycles. The coulomb efficiency of the composites is above 95%. In addition, the rate capability of these composites is much better than that of sulfur. Sulfur molecules can be evenly distributed between the graphene layers and fixed to the functional groups on the surface of graphene by this one-step hydrothermal method. © Editorial office of Acta Physico-Chimica Sinica.