Synthesis and electrochemical performance of CoO/graphene nanocomposite as anode for lithium ion batteries

We developed one-spot in situ synthesis method to fabricate CoO/reduced graphene oxide (CoO/RGO) nanocomposite by directly employing C4H6O4·Co·4H2O and hydrophilic graphite oxides as raw materials. The electrochemical performances of the as-prepared CoO/RGO nanocomposite were evaluated in coin-type cells. It delivers a high reversible capacity of 740.7 mAh g−1 at 100 mA g−1, and retains a capacity retention of 95% after 50 cycles. Even after 435 cycles at various rates from 100 to 4000 mA g−1, the capacity still retains 577.9 mAh g−1 when the current density is back to 100 mA g−1. The extraordinary performance is ascribed to the well-designed structure of the CoO/RGO nanocomposite. The small-sized, high crystalline and dense CoO nanoparticles uniformly disperse on conductive graphene substrates, supplying large number of accessible active sites for lithium-ion insertion, short diffusion length for lithium ions, good conductivity and strong interfacial interaction between CoO nanoparticles and RGO nanosheets, which are beneficial for high capacity and long cycling stability.