Preparation of graphene/sulfur composite in liquid phase and its application as cathode in lithium-sulfur batteries

Abstract The high-performance reduced graphene oxide/sulfur (rGO/S) composite cathode was obtained by integrating sulfur nanoparticles with graphene oxide (GO) in liquid phase reduction by self-assembly process. The morphology and microstructure of the materials were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM),X-ray diffractometer (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results show that sulfur nanoparticles are uniformly distributed among the graphene sheets and effectively encapsulated by the graphene sheets. The mass fraction of sulfur in 35-rGO/S composite is as high as 83.6%. The initial discharge capacity of the 35-rGO/S composite cathode can reach 1197.3 mAh·g-1 at a current density of 0.2 C, and the capacity remains 730 mAh·g-1 after 200 cycles, manifesting outstanding cycling stability.