Fabrication of graphene/copper-nickel foam composite for high performance supercapacitors

A three dimensional (3D) composite electrode of graphene/copper-nickel foam (CNF) was fabricated by successively immersing commercial CNF into polydopamine (PDA) aqueous solution and graphene oxide (GO) suspension solution, followed by an annealing process. CNF acted as a substrate for the composite film, as well as the copper and nickel source, and the formation of reduced graphene oxide (rGO) and nitrogen doping were achieved simultaneously during the annealing process. The novel rGO/PDA/CNF composite electrode exhibited an ultrahigh specific capacitance of 2427.3 F g^-1 at 2 A g^-1, a superior rate capability of 52.1% capacitance retention at 50 A g^-1vs. 1 A g^-1, an excellent cycling stability that meant the specific capacitance reached its maximum value after being fully activated and retained 99.5% of the value even after 5000 cycles, a maximum energy density of 92.9 W h kg^-1 and a power density of 9.6 kW kg^-1 in 1 M KOH electrolyte. The synthesis method and excellent properties offer an effective strategy for fabricating various composites and exhibit promising applications in energy storage devices.