Effects of ultrasonic power on the electrochemical characteristics of high-performance nanosized zinc–cobalt oxide electrodes for asymmetric supercapacitors

Abstract

This study reports the preparation of ZnCo2O4 oxide (ZCO) electrode materials with favorable microstructure and porosity arrangement via ultrasonic electrodeposition-calcination. The application of ultrasonic waves at a power of 200 W (using ZCO-2) led to the development of a smooth and flat microstructure, characterized by the presence of numerous micropores. The lattice constant of ZnCo2O4 in the ZCO-2 oxide electrode material was determined to be 0.428 nm via TEM analysis. Furthermore, the XRD analysis of ZCOs demonstrated the effective synthesis of ZnCo2O4 electrode materials. The main lattice diffraction planes of ZCOs were observed at (111), (220), (311), (400), (511), and (440), with corresponding diffraction angles of 29.8°, 36.4°, 42.9°, 45.2°, 62.3°, and 66.5°, respectively. The application of 200 W ultrasonic power during electrochemical experiments significantly improved the electrochemical performance of ZCO-2. The ZCO-2 oxide electrode demonstrated remarkable area capacitance and negligible electrical impedance. At a current density of 3 mA/cm2, the area capacitance was measured to be 1.803 F/cm2. The ZCO-2 oxide electrode showed remarkable capacitance retention of 67.3 % even under high current density conditions. Furthermore, the asymmetric supercapacitor composed of ZCO-2 and AC (ZCO-2/AC ASC) showed outstanding electrochemical performance. The ZCO-2/AC ASC showed a capacitance of 5.721 F/cm3 at a current density of 0.5 mA/cm2. Furthermore, it demonstrated an energy density of 68.2 Wh/kg at a power density of 250 W/kg. The capacitor showed consistent performance and retained 63.8 % of its initial capacitance even after undergoing 24,000 cycles. Furthermore, the findings of this research provide substantial implications for the combination of ultrasonic electrodeposition with capacitors, while also presenting an innovative concept for electrode materials in high-performance supercapacitors.