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

Abstract

Spinel-type metal oxides have attracted significant interest as stable, efficient electrode materials for energy storage devices. This research work focuses on synthesising ZnCo<inf>2</inf>O<inf>4-x</inf>S<inf>x</inf> 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 ZnCo<inf>2</inf>O<inf>4-x</inf>S<inf>x</inf> exhibits a mesoporous texture and achieves an appropriate specific surface area of 36.37 m2 g−1. The as-prepared ZnCo<inf>2</inf>O<inf>3.925</inf>S<inf>0.075</inf> 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 ZnCo<inf>2</inf>O<inf>3.925</inf>S<inf>0.075</inf> 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 ZnCo<inf>2</inf>O<inf>4-x</inf>S<inf>x</inf> with optimal sulfur content could be a promising candidate for high-performance energy storage systems. © 2026 Elsevier B.V.