Preparation and electrochemical capacitance of binder-free different micromorphology nickel sulfide on nickel foam for asymmetric supercapacitor

Building energy storage equipment like supercapacitors becomes particularly important because of the growth in energy consumption. The electrochemical material of supercapacitor is one of the significant constituent parts, which directly affect the performance of supercapacitors. The electrode of a supercapacitor generally consists of a base material, an active material, and a binder between the base and active materials. The use of a binder can increase the resistance of internal system. Therefore, it is very important to prepare non-adhesive electrode materials. Nickel sulfides have smaller band gap than that of transition metal oxides, high conductivity, and have been widely welcomed by researchers in recent years. In this paper, binder-free different micromorphology nickel sulfide based on nickel foam (Ni₃S₂/NF) was fabricated by means of electrochemical reaction method. The microtopography and specific capacitance of these Ni₃S₂/NF electrodes had obvious distinction at different speed rates of preparation. The diameter of the prepared Ni₃S₂ particles varied from more than 100 nm to more than 1000 nm. The best-performing Ni₃S₂/NF was prepared at the sweep speed of 800 mV s⁻¹ in the electrochemical deposition process. The best-performing Ni₃S₂/NF delivered a mass-specific capacity of 1193.83 F g⁻¹ and an area-specific capacity of 235.83 mF cm⁻². The obtained capacity retention rate was 49.20% after charging and discharging 5000 times. An asymmetric supercapacitor was also constructed in order to realize the application of Ni₃S₂/NF. The asymmetric supercapacitor delivered an area-specific capacity of 69.67 mF cm^–2 and obtained capacity retention rate of 41.25% after charging and discharging 5000 times.