Nickel sulfide film by potentiodynamic deposition as competent electrode for supercapacitor

Abstract Nanostructures of transition metal sulfides can be important electrodes to achieve high performance supercapacitors. Creation of binder-less electrodes of these materials is a challenge. The present potentiodynamic electrodeposition technique helps to achieve these objectives and the studied supercapacitors exhibit a good performance. The potentiodynamic method is used to efficiently install binder-free stable film of nickel sulfide (Ni_3S_2) on a copper electrode at ambient conditions in neutral pH to explore its symmetric supercapacitor capabilities. The method yields nano-sized particles tightly bonded into 3D-porous structures. This alleviates large internal surface areas, mechanical stability, short ion diffusion length, and better ion-conducting pathways, which are essential properties of electrodes for a better supercapacitor. The supercapacitor was constituted with 2 M KOH electrolyte which shows a high specific capacity of 168.4 Cg^−1 at 2.5 Ag^−1 (758 Fg^−1 at 2.5 Ag^−1) and good stability up to 3000 charge–discharge cycles, high rate capability, and high energy and power density. Therefore, these hybrid electrodes can be promising materials for electrochemical energy storage systems. Graphical abstract Discussion Development of supercapacitor with high energy content, low cost, and environmental friendly is a great challenge. Microscopic electrochemical understanding of electrode and electrolytic interaction and the possible mechanisms of charge storage are critically important parameters to develop robust energy storage systems.