Graphene oxide nano-sheets wrapped Cu2O microspheres as improved performance anode materials for lithium ion batteries
Cu2O microspheres were successfully encapsulated by graphene oxide (GO) nano-sheets and used directly as the anode material for lithium ion batteries. The core–shell structured Cu2O@GO composite delivered a reversible capacity of 458 mA h g−1 at a current density of 100 mA g−1 after 50 cycles. Even at a high charge–discharge rate of 1000 mA g−1, Cu2O@GO still demonstrated a reversible capacity of 240 mA h g−1 after 200 cycles, significantly higher than those of the bare Cu2O microspheres (37 mA h g−1) and GO nano-sheets (11 mA h g−1). The rate capability evaluated by the ratio of capacity at 100 mA g−1/1000 mA g−1 current density was 49%, 25% and 9.8% for Cu2O@GO, bare Cu2O and GO, respectively. The greatly enhanced performance for GO nano-sheets wrapped Cu2O microspheres composite mainly resulted from the synergistic effect of Cu2O microspheres and GO nano-sheets core–shell composite: the flexible in-situ electrochemically reduced GO nano-sheet coating layer functioning as an efficient three dimensional (3D) conductive network and lithium storage active material; the Cu2O microsphere core functioning as a skeleton to support multilayer GO sheets and avoid GO nano-sheets aggregation.