A novel binder-free electro-synthesis of hierarchical nickel sulfide nanostructures on nickel foam as a battery-type electrode for hybrid-capacitors

Abstract

In this work, we have synthesized hierarchical nickel sulfide nanoparticles on nickel foam (NiS@Ni) via simple cathodic electrodeposition using aqueous nickel chloride (NiCl2) and thiourea mixtures as an electrolyte. The synthesized NiS@Ni are characterized using important surface analytical tools such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) with energy dispersive spectrum (EDS) and elemental mapping analysis. The positive electrode performance of NiS@Ni is tested in aqueous potassium hydroxide (KOH) by common electroanalytical techniques. The cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) curves of NiS@Ni exposed clear reversible redox peaks acknowledged the Faradaic battery-type performance in aqueous KOH. Moreover, the synthesized NiS@Ni delivers maximum specific capacities of 1109C/g (308.05 mAh/g) and 532C/g (147.8 mAh/g) at a scan rate of 5 mV/s and 2 A/g of current density, respectively. Therefore, the synthesized hierarchical NiS@Ni can be applied as a battery-type positive electrode in hybrid-capacitors.