Microwave-assisted synthesis of hollow CuO-Cu2O nanosphere/graphene composite as anode for lithium-ion battery

CuO-Cu2O/graphene composite has been successfully prepared by the combination of a microwave-assisted process and subsequent annealing. X-ray diffraction and electron microscopy reveals that copper oxide nanospheres with a size of 120-200 nm are uniformly anchored on graphene nanosheets. The copper oxide nanospheres are composed of numerous CuO and Cu2O nanocrystals of ∼10 nm. These nanospheres are hollow and the thickness of the shells is around 50-70 nm. The CuO-Cu2O/graphene composite shows a highly reversible capacity and excellent rate performance as anode for Li-ion battery. The reversible capacity of the composite retains 487 mA h g−1 after 60 cycles at 200 mA g−1. Even when cycled at various rate (200, 500, 1000, 2000, 5000 mA g−1) for 60 cycles, the capacity can recover to 520 mA h g−1 at the current of 200 mA g−1. The enhanced electrochemical performances are ascribed to the hollow spherical architectures, excellent conductivity of graphene sheets, and possible synergistic effects between CuO, Cu2O and graphene that enhance the intrinsic properties of each component.