Rapid Oxidation Synthesis of Hollow Cupric Oxide-Decorated rGO with High Performance and Kinetically Enhanced Lithium Storage

From the perspective of promotion of metal oxide anodes' performance, structural design and reinforcement of carbon materials are always concerned as useful methods. In addition, high hope is being placed on the use of graphene as an ideal potential carbon reinforcement material for an abundant energy market, but currently, commercial graphene has poor intrinsic properties, which hamper its development in the energy storage area. Therefore, combining the metal oxide materials with commercial graphene by a rational structure design could be a more hopeful method to realize the productive use of commercial graphene in the energy storage area. In this work, hollow cupric oxide (CuO) decorated on reduced graphene oxide (rGO) is prepared by an effective glycol-water combined rapid oxidation strategy. The well-designed composite yields a high initial capacity of 1491 mAh/g and maintains 960 mAh/g after 500 cycles at 1.0 A/g. The remarkable reversible capacity may be attributed not only to the hollow structure of CuO, but also to the bidirectional synergy between graphene and the small-sized CuO. The galvanostatic intermittent titration technique (GITT) and density functional theory (DFT) calculation are conducted to analyze the relationship between the electrochemical properties and surface states. The GITT test shows that the ion diffusion coefficient is higher when the smaller hollow CuO is decorated on rGO. Additionally, the DFT results indicate that more active electrons appear on the surface of the composite. As a result, the as-prepared hollow and smaller CuO-decorated rGO presents excellent performance in terms of specific capacity and rate capability.