Temperature dependent synthesis of Cobalt copper nickel oxide composite for supercapacitor applications

Supercapacitors have evolved as a viable energy storage technology owing to their higher power density, longer cycle life, and rapid charge–discharge features. The electrochemical performance of supercapacitor electrodes is highly affected by their structural and morphological characteristics, which are in turn dependent on synthesis parameters. This study looks into how to make a Co-Cu-Ni oxide composite (130 –160 °C) that can be used as high-performance supercapacitor electrodes. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the composite made at 150 °C had the best crystallinity and a flower-like shape in three dimensions. The mixed metal oxide phases and their combined redox activity were confirmed by Raman and X-ray photoelectron spectroscopy (XPS). Electrochemical analysis showed a very high specific capacitance of 306.28 F/g at 4 mA/cm2, with faster charge transfer kinetics, as shown by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). A symmetric supercapacitor device fabricated using the optimized material and PVA + KOH gel electrolyte demonstrated a specific capacitance of 45.82 F/g at 5 mA/cm2, a maximum energy density of 14.31 Wh/kg at 5 mA/cm2, and a maximum power density of 3658 W/kg at 20 mA/cm2, highlighting excellent practical applicability. Moreover, the device retained 44.4% of its initial capacitance after 1300 cycles, confirming moderate long-term stability. This work is unique in demonstrating that simple thermal control during synthesis can significantly tailor the structural and electrochemical properties of a ternary oxide composite. The approach presents a scalable and cost-effective route for the development of next-generation energy storage devices.