Tailoring supercapacitor performance via sulfur engineering in ternary CoNiMoS electrodes

Abstract

In this work, porous CoNiMoS (CNMS)-based ternary nanoflower arrays were successfully grown on nickel foam (NF) using a two-step strategy involving hydrothermal synthesis followed by a solvothermal sulfidation process. The influence of sulfidation concentration was systematically investigated to optimize the electrochemical performance. The optimized CNMS@NF electrode exhibits a pronounced charge–discharge activation behaviour and delivers a high specific capacitance of 1940 F g⁻¹ at 1 A g⁻¹. The hierarchical porous architecture, derived from hydroxide precursors, enables improved electrolyte diffusion and efficient exposure of active sites. Notably, this structural evolution leads to a substantial reduction in solution impedance from 4.1 Ω to 2.12 Ω, enhancing charge transport kinetics. The electrode achieves an impressive energy density of 349.2 Wh kg⁻¹ and a power density of 1631 W kg⁻¹, while retaining 70% of its initial capacitance after 4000 charge–discharge cycles, demonstrating excellent long-term stability. The superior electrochemical performance is attributed to the synergistic interaction among Co, Ni, and Mo species and the enrichment of S²⁻ anions, which collectively stabilize the nanoflower structure and promote robust redox activity. These findings position the CNMS@NF electrode as a promising candidate for high-performance energy storage applications.