In Situ Fabrication of CoS and NiS Nanomaterials Anchored on Reduced Graphene Oxide for Reversible Lithium Storage

CoS and NiS nanomaterials anchored on reduced graphene oxide (rGO) sheets, synthesized via combination of hydrothermal with sulfidation process, are studied as high-capacity anode materials for the reversible lithium storage. The obtained CoS nanofibers and NiS nanoparticles are uniformly dispersed on rGO sheets without aggregation, forming the sheet-on-sheet composite structure. Such nanoarchitecture can not only facilitate ion/electron transport along the interfaces, but also effectively prevent metal-sulfide nanomaterials aggregation during the lithium reactions. Both the rGO-supported CoS nanofibers (NFs) and NiS nanoparticles (NPs) show superior lithium storage performance. In particular, the CoS NFs-rGO electrodes deliver the discharge capacity as high as 939 mA h g–1 after the 100th cycle at 100 mA g–1 with Coulombic efficiency above 98%. This strategy for construction of such composite structure can also synthesize other metal-sulfide-rGO nanomaterials for high-capacity lithium-ion batteries.