Highly uniform Co9S8 nanoparticles grown on graphene nanosheets as advanced anode materials for improved Li-storage performance

A Co 9 S 8 /GNS (graphene nanosheets) nanocomposites has been synthesized via a facile solvothermal approach followed by thermal treatment in nitrogen at 500   °C using graphite oxide sheets, CoCl 2 ·6H 2 O and thiourea as the starting materials. Highly uniform Co 9 S 8 nanoparticles with a size of about 80–90   nm are evenly grafted on the surface of GNS , forming a unique Co 9 S 8 /GNS hybrid nanostructure. When evaluated as anode materials for lithium ion batteries, impressive electrochemical performances of the as-prepared nanocomposites are achieved compared to that of pure bulk Co 9 S 8 , with an high reversible capacity of 1480   mAh   g −1 . Moreover, the as-synthesized nanocomposites present excellent cycling durability and high-rate capability. The improvement in the electrochemical properties could be attributed to the well-designed structure of the Co 9 S 8 /GNS nanocomposite which possesses large number of accessible active sites for lithium-ion insertion, fast ion diffusion rate and good electronic conductivity.