Synthesis of the ZnCo2O4 Positive Electrode Using a Urea-Assisted Hydrothermal Approach for Supercapacitor Applications

Spinel-structured oxides are cost-effective and environmentally friendly, making them attractive candidates for supercapacitor electrode applications. However, their limited electrical conductivity and low energy density hinder their widespread utilization. In this study, ZnCo2O4 nanomaterials were synthesized using a simple hydrothermal method, followed by a calcination process with controlled urea molar concentration. The resulting samples exhibited a significant specific surface area, which reduced the widths of ion diffusion channels while simultaneously increasing the number of active sites. At a current density of 7 mA/cm2, the ZnCo2O4 nanoparticles synthesized with a 0.9 M urea concentration demonstrated a remarkable specific capacitance of 635 F/g. Furthermore, the performance evaluation revealed an energy density of 31.9 W h/kg and a power density of 143.7 W/kg. In its assembled configuration, the asymmetric supercapacitor exhibited an energy density of 9.29 W h/kg at a power density of 426 W/kg. Furthermore, the device demonstrated excellent cyclic stability, maintaining 78% of its capacitance after 10,000 cycles. These findings suggest that the device could be a viable option for various portable energy storage applications.