Nickel Disulfide-Graphene Nanosheets Composites with Improved Electrochemical Performance for Sodium Ion Battery

Nickel disulfide-graphene nanosheets (NiS2-GNS) composites were successfully synthesized via a simple and mild hydrothermal method. It was revealed by scanning electron microscopy and transmission electron microscopy images that the spherical NiS2 nanoparticles with a diameter of 200-300 nm were uniformly dispersed on graphene nanosheets. Na(+) electrochemical storage properties including cycling performance and high-rate capability of NiS2-GNS composites were investigated, demonstrating a superior reversible capacity of 407 mAh g(-1) with the capacity retention of 77% over 200 cycles at a current density of 0.1 C. Furthermore, even at a large current density of 2 C, a high capacity of 168 mAh g(-1) can still remain, which is much higher than that of pristine NiS2 materials. The enhancement in electrochemical properties might be attributed to the synergetic effect endowed by high conductivity of graphene and novel structure of the electrode material. Combined with the advantages of low cost and environmental benignity, NiS2-GNS composite would be a potential anode material for sodium ion batteries.