Facile Synthesis of Three-Dimensional Ternary ZnCo2O4/Reduced Graphene Oxide/NiO Composite Film on Nickel Foam for Next Generation Supercapacitor Electrodes

Ternary ZnCo2O4/reduced graphene oxide/NiO (ZCGNO) nanowire arrays were grown directly on a piece of Ni foam using a simple, facile, cost-effective hydrothermally assisted thermal annealing process without the addition of any Ni precursor salt and used as a binder-free supercapacitor electrode. Ni foam was utilized successively as the NiO precursor, binder, and current collector. The resulting 3D ternary composite possessed an ultrahigh specific capacitance of 1256 F/g at a current density of 3 A/g in 6 M KOH solution. Moreover, the three-dimensional electrode exhibited superior electrochemical performance, such as excellent cyclic stability (∼80% capacitance retention after 3000 cycles), maximum energy density of 62.8 Wh/kg, maximum power density of 7492.5 W/kg, and low equivalent series resistance (0.58 Ω). The effects of the electrolyte concentration on the electrochemical performance of ZCGNO were also examined. ZCGNO with this remarkable electrochemical performance may be considered a prospective candidate for high performance supercapacitor applications.