Preparation and performance of a graphene-(Ni-NiO)-C hybrid as the anode of a lithium-ion battery

A graphene-(Ni-NiO)-C hybrid was prepared by dissolving nickel acetate and glucose in water to form a solution that was mixed with a graphene oxide (GO) aqueous suspension, hydrothermally treated at 180 °C for 24 h, carbonized at 700 °C for 3 h in Ar and calcined at 300 °C for 3 h in air. Results indicated that Ni(OH)₂ formed during the hydrothermal treatment was converted to metallic Ni during carbonization, which was partly oxidized to NiO during calcination. When used as the anode material of a lithium-ion battery, it had a high initial capacity of 711.6 mA h g⁻¹, which increased to 772.1 mA h g⁻¹ after 300 cycles. For comparison, the sample without added GO had a much lower initial capacity of 584.7 mA h g⁻¹, which decreased to 148.8 mA h g⁻¹ after 300 cycles. Hybridization of the Ni-NiO nanoparticles with carbon inhibited their aggregation. The GO addition led to the formation of a conducting network, which alleviated the large volume expansion during lithiation, prevented the electrode from cracking during cycling and increased the surface area for easy access of the electrolyte. These factors jointly contributed to the obvious improvement in the electrochemical performance of the graphene-(Ni-NiO)-C anode.