Abstract

An optimized nanostructure design for electrode materials for high-performance lithium-ion batteries was realized by introducing three-dimensional (3D) graphene networks into transition metal oxide nanomicrostructures. A CuO/graphene composite was selected as a typical example of the optimized design. Self-assembled CuO and CuO/graphene urchin-like structures have been successfully synthesized by a simple solution method and investigated with SEM, TEM, XRD, and electrochemical measurements. The CuO/graphene nanocomposite exhibits a remarkably enhanced cycling performance and rate performance compared with pure CuO urchin-like structure when being used as anode materials in lithium-ion batteries. During all the 100 discharge-charge cycles under a current density of 65 mA g−1, the CuO/graphene electrode can stably deliver a reversible capacity of ca. 600 mA h g−1. At a high current density of 6400 mA g−1, the specific charge capacity of the CuO/graphene nanocomposite is still as high as 150 mA h g−1, which is three times larger than that of graphene (48 mA h g−1), while that of CuO is nearly null under the same current density. The enhancement of the electrochemical performance could be attributed to the 3D electrically conductive networks of graphene as well as the unique nanomicrostructure of the CuO/graphene nanocomposite in which the CuO nanomicroflowers are enwrapped by a thin layer of graphene as an elastic buffer.