Effect of deposition potential and annealing on performance of electrodeposited copper oxide thin films for supercapacitor application

The present investigation describes the effect of deposition potential and annealing on copper oxide (CuO) thin film as a supercapacitor electrode. CuO thin films were grown on conducting glass substrate (ITO) by electrodeposition at room temperature and annealed for 3 hrs. at 300° C. The formation of polycrystalline CuO was confirmed by X-ray diffraction (XRD) & X-ray photoelectron spectroscopy (XPS). Significant change in morphology of CuO thin films after annealing has been observed. Annealing has improved crystallinity, surface coverage and grain connectivity of CuO thin films. CuO thin films deposited at −450 mV vs. Ag/AgCl exhibits essential porosity for electrochemical reactions. Higher deposition potential of −500 mV vs. Ag/AgCl leads to formation of compact CuO thin films. Electrochemical performance of as deposited and annealed CuO thin films were compared using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M aqueous KOH electrolyte. The maximum specific capacitance of 57.44 F/g at 20 mV/s was measured. The CuO thin film shows specific energy of 2.67 Wh/kg with a coulombic efficiency of 77.27 % at 0.5 mA/cm² current density. These results showed that the electrodes prepared by simple, low-cost electrodeposition method can be promising electrode materials for supercapacitor application.