MWCNTs/NiS2 decorated Ni foam based electrode for high-performance supercapacitors

We report here a novel ex-situ synthesis of MWCNTs/NiS2 nanocomposite on nickel foam as electrode material for supercapacitor applications. Nickel disulfide (NiS2) nanoparticles were synthesized using a one-step solid-state method followed by the preparation of MWCNTs/NiS2 nanocomposite using the ultra-sonication technique. The structural characterization was carried out using X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) analysis. The capacitive properties were studied using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) method in 2 M KOH solution. The MWCNTs/NiS2 electrode with a 20% weight fraction of multi-walled carbon nanotubes (MWCNTs) showed the best electrochemical properties having a maximum specific capacitance of 2054.28Fg-1 at a 2Ag-1 current density and excellent cyclic stability. The electrode retained 99.99% specific capacitance even after 10,000 cycles. The enhanced electrochemical properties of the NiS2 electrode can be attributed to fast diffusion paths provided by CNTs and enhanced redox reactions of NiS2 nanoparticles due to high surface area, decreasing the overall resistance of electrode which is in agreement with the data obtained by electrochemical impedance spectroscopy (EIS).