Tailoring the anion-doped ZnCo2O4-xSx nanostructures via surfactant-assisted hydrothermal method for enhanced supercapacitor performance

Spinel-type metal oxides have attracted significant interest as stable, efficient electrode materials for energy storage devices. This research work focuses on synthesising ZnCo₂O_4-xS_x nanostructures (x = 0, 0.05, 0.075, and 0.10) via a surfactant-assisted hydrothermal process using thiourea as the sulfur source for partial oxygen substitution. The synthesised ZnCo₂O_4-xS_x exhibits a mesoporous texture and achieves an appropriate specific surface area of 36.37 m² g⁻¹. The as-prepared ZnCo₂O_3.925S_0.075 exhibits a remarkable specific capacitance of 1104 F g⁻¹ at 1, with high capacitance retention of 96.63 % after 10,000 charge/discharge cycles, indicating superior electrochemical characteristics compared to the other prepared samples. The constructed asymmetric device using a ZnCo₂O_3.925S_0.075 electrode has offered an energy density of 28.18 Wh kg⁻¹ and a power density of 3272.5 W kg⁻¹. The obtained electrochemical assessments of the as-prepared electrode material confirm its practical applicability in energy storage devices, owing to its high specific capacitance, high power density, and excellent cycling stability. Further, this study proposes that surfactant-assisted ZnCo₂O_4-xS_x with optimal sulfur content could be a promising candidate for high-performance energy storage systems.