Abstract
This work investigates the impact of different ultrasonic treatment durations on the synthesis and electrochemical performance of NiZnCo(2)O(4) (NZC) supercapacitor electrodes. Optimizing treatment to 20 min resulted in a uniform, compact NiZnCo(2)O(4) layer with improved nanostructures, which increased the surface area and active sites for electrochemical reactions. X-ray diffraction (XRD) confirmed successful NiZnCo(2)O(4) synthesis, revealing distinct crystalline phases of NiO, ZnCo(2)O(4), and Co(3)O(4), with improved crystallinity. Electrochemical tests, conducted using a 1.0 M KOH electrolyte, demonstrated that the NZC-2 electrode treated for 20 min achieved the highest 5.678 F/cm(3) volumetric capacitance at 0.5 mA/cm(2) current density along with 70.5 Wh/kg an energy density at 260 W/kg power density. The galvanostatic charge-discharge and cyclic voltammetry tests revealed that NZC-2 maintained superior charge-discharge efficiency, showing the longest discharge time at 1 mA/cm². Electrochemical impedance spectroscopy (EIS) measurements demonstrated that NZC-2 exhibited the lowest total impedance, thereby enhancing ion transport efficiency. The NZC-2/AC asymmetric supercapacitor showed excellent long-term stability, retaining 64.2% of its capacity after 20,000 charge-discharge cycles. It successfully powered a 1.2 V small fan, demonstrating its practical applicability. The results highlight the crucial importance of ultrasonic treatment in greatly improving the structural and electrochemical characteristics of NiZnCo(2)O(4) electrodes, which opens up possibilities for the advancement of high-performance supercapacitors.