Synthesis and electrochemical performances of cobalt sulfides/graphene nanocomposite as anode material of Li-ion battery

The cobalt sulfides/graphene nanosheets (GNS) composite is prepared by a facile one-pot solvothermal route in the presence of graphene oxide sheets (GOS). XRD, SEM and TEM characterizations show that sphere-like cobalt sulfides particles with an average size of about 150 nm, which are complicated phases of CoS2, CoS and Co9S8, are highly dispersed on or wrapped in the creasy graphene. The selective nucleation and growth of cobalt sulfides particles on GOS make the particles more uniform in morphology and size. The as-fabricated cobalt sulfides/GNS composite exhibits very high electrochemical lithium storage reversible capacity of about 1018 mAh g(-1). Moreover, the cobalt sulfides/GNS composite still remains reversible capacity of above 950 mAh g(-1) after 50 cycles at a current density of 100 mA g(-1) as well as at the different current densities from 100 to 1000 mA g(-1), proving its excellent cycling durability and high-rate capability. The superior electrochemical performances of the composite may be attributed to the robust composite structure and superior conductivity, high charger mobility, large surface area and good flexibility of graphene. (C) 2013 Elsevier B.V. All rights reserved.