Sub-10-nm Co3O4 nanoparticles/graphene composites as high-performance anodes for lithium storage

Abstract To improve the electrochemical performance of Co 3 O 4 /graphene composites towards high-performance lithium ion batteries, various facile chemical methods have been developed to form hybrid Co 3 O 4 /graphene composites, but the compositions of these composites were considerably different. In this study, a two-step solvothermal synthesis method was employed to accurately control the concentration of Co 3 O 4 nanoparticles (NPs) with particle sizes less than 10 nm in the composite. The Co 3 O 4 /reduced graphene oxide (RGO) composites exhibited the highest reversible capacity of 1600 mAh g −1 at 43 wt% Co 3 O 4  NPs. The synergic effects of the sub-10-nm sized Co 3 O 4 and the RGO sheets resulted in improved reversible capacity, cycling stability, and rate capability, which are caused by a large number of active sites and the short diffusion pathways provided by the nano-sized Co 3 O 4 , as well as the elastic buffer space and conductive pathway provided by the RGO sheets.