Carbon Nanotubes/Graphene Composites Treated by Nitrogen-Plasma and Covered with Porous Cobalt Oxide through Galvanostatic Electrodeposition as well as Annealing for Anode Materials of Lithium-Ion Batteries

Abstract

Carbon nanotubes/graphene composites are grown on nickel foil without additional catalysts by chemical vapor deposition. Next, to improve the anchoring and uniform dispersing of Co(OH)₂ onto carbon nanotubes/graphene composites, the carbon nanotube/graphene composites are modified by radio frequency nitrogen-plasma. Then porous Co(OH)₂ thin films are galvanostatically electrodeposited onto N-doped carbon nanotubes (CNTs)/graphene composites at different currents and time periods. Finally, the porous Co(OH)₂ is transformed into porous Co₃O₄ by annealing. The charge specific capacity (1290 mAh g⁻¹) reaches a maximum at the galvanostatic electrodeposition condition (current = 1.5 mA and time = 300 s) for the coin cell. Furthermore, Co₃O₄/N-doped CNTs/graphene possesses higher charge (discharge) specific capacity and better electrochemical stability in comparison to Co₃O₄/CNTs/graphene for the coin cell (full cell: i.e. lithium-ion battery).