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 (similar to 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 Omega). The effects of the electrolyte concentration on the electrochemical performance of ZCGNO were also examined. ZCGNO with this remarkable electro- chemical performance may be considered a prospective candidate for high performance supercapacitor applications.