Surfactant Free Nickel Sulphide Nanoparticles for High Capacitance Supercapacitors

The surfactant free nickel sulphide nanoparticles were synthesized via facile hydrothermal method towards supercapacitor applications. The formation of crystalline spherical nanoparticles was confirmed through structural and morphological studies. Electrochemical behaviour of the electrode was analyzed using cyclic voltammetry (CV), galvanostatic charge-discharge studies (GCD) and electrochemical impedance spectroscopy (EIS). The CV studies imply that specific capacitance of the electrode arises from a combination of surface adsorption and Faradic reaction. The NiS electrode delivered a specific capacitance of about 529 F g(-1) at a current density of 2 A g(-1) (GCD measurements). A profitable charge transfer resistance of 0.5 Omega was obtained from EIS. The 100 % of capacity retention even after 2000 repeated charge-discharge cycles could be observed in 2 M KOH electrolyte at a much larger rate of 30 A g(-1). The experimental results suggest that nickel sulphide is a potential candidate for supercapacitor applications.