Monodispersed NiCo₂S₄ nanoparticles are grown in-situ on nickel foam by a one-step colloidal synthetic route, and they deliver a high specific capacitance of 1790.8 F/g at 1 A/g via a three-electrode system and also maintain outstanding energy-storage capacity, high energy density and stability in a two-electrode cell. This study provides a feasible way to design and fabricate electrodes effectively.

Abstract

One-step colloidal synthetic route was adopted to in-situ grow monodispersed NiCo₂S₄ nanoparticles (NPs) on nickel foam (NF) from metallic salts with benzyl disulfide in the media of oleylamine and octadecene. Owing to the favorable dispersion and considerable redox activity of NiCo₂S₄ along with tight and binder-free connection with NF, the obtained battery-type supercapacitor delivered a specific capacitance of 1790.8 F g⁻¹ at 1 A g⁻¹ via a three-electrode system. Simultaneously, it just degraded 40 % at 20 A g⁻¹ and maintained 86.8 % of initial specific capacitance (C₀) after 2000 cyclic trials at 10 A g⁻¹. When the NiCo₂S₄ NPs were assembled with active carbon (AC) forming an asymmetric capacitor device of NiCo₂S₄ NPs//AC, it delivered an energy density (E) of 48.7 W h kg⁻¹ at a power density (P) of 161.1 W kg⁻¹, and kept 21.9 W h kg⁻¹ at a high P of 8.05 kW kg⁻¹. Meanwhile, the capacitor manifested preeminent cycling life (C=94.5 % C₀ after 5000 cyclic trials) at 5 A g⁻¹. The in-situ grown NiCo₂S₄ NPs on NF without any binder exhibited high performance in energy storage, providing a feasible way to improve the electrochemical performance of the electrode materials.