Transition metal oxide-based NiO–Co₃O₄ nanocomposite as an electrode material for the high-performance supercapacitor

The simple hydrothermal approach was used to synthesize the NiO–Co₃O₄ nanocomposite. The effect of molar ratios of Ni and Co were studied. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy. (FE-SEM) with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The NiO–Co₃O₄ nanocomposite with 1:1 ratio exhibited high specific capacitance of 1466 F/g at a scan rate of 10 mV/s and 1018 F/g at current density of 2 A/g. Furthermore, a pouch-type symmetric supercapacitor is fabricated using NiO–Co₃O₄ as cathode and anode in 1 M KOH as electrolyte, which showed an excellent specific capacitance of 372 F/g at a current density of 2 A/g. The device showed high energy density of 46.511 Wh/kg at 2093 W/kg. In addition, the device showed superior cyclic stability with a retention of 93% over 1000 cycles at 5 A/g. The enhanced electrochemical performance suggested that NiO–Co₃O₄ nanocomposite would be an ideal candidate for supercapacitors.