Supercapacitive characteristics of potentiodynamically-deposited nano-structured cobalt-nickel oxide

The amorphous cobalt-nickel oxide nano-rods (diameter: 20-30 nm, length: 100-150 nm) were potentiodynamically deposited onto a stainless-steel electrode. Their structure and surface morphology were investigated by means of X-ray diffraction analysis and scanning electron microscopy. Their capacitive characteristics were evaluated in 1 M KOH electrolyte by using cyclic voltammetry and constant current charge-discharge methods. It was found that the capacitive characteristics of deposited cobalt-nickel oxide were strongly influenced by the deposition condition. A high specific capacitance value of ∼370 F/g and a specific power of 29 kW/kg were obtained when cobalt-nickel oxide was deposited in the aqueous solution of 0.15 M NiCl₂ · 6H₂O + 0.05 M COCl₂ · 6H₂O in potentiodynamic conditions. In comparison, the specific capacitance values for the deposited cobalt oxide and nickel oxide were 184 F/g and 118 F/g, respectively. The cycle-life test showed that the specific capacitance of cobalt-nickel oxide was highly stable even after 100,000 cycles, indicating its high potential for supercapacitor applications.