Sulfurization temperature dependent supercapacitive performance of NiS electrode: An advanced method to boost nanostructures on nickel foam

In present study, morphological dependent nickel sulfide (NiS) electrode was deposited at different deposition temperature (DT-120 °C, DT-150 °C and DT-180 °C) through hydrothermal. The SEM analysis images presented that the dense nanostructures were converted into nano-gel/sheets by increasing the DT: 120–180 °C. The BET analysis results confirmed that nano-gel/sheets nanostructures were exhibited high surface area 159 m²g^-1 than 74 m²g^-1 of dense nanostructured NiS electrode. The supercapacitive analysis confirmed that specific capacitance increased from 1126 F/g to 3585 F/g (at 1.5 A/g) with cyclic life 82.5–95.12 % (for 12000 cycles) with increasing DT 120–180 °C. The development and crosslinking of nano-gel/sheets enabled NiS electrode to exhibit excellent structural stability even for 12000 cycles. The increasing DT enhanced the diffusion contribution from 94 to 96 % at 3 mV/s suitable for pseudocapacitors applications. Moreover, an asymmetric supercapacitive device assembled by NiS and AC electrode exhibited specific capacitance of 733 F/g, energy density of 229–126 Wh/kg, power density of 1500–5250 W/kg and cyclic life of 91 % even after 10000 cycles. The prepared nano-gel/sheets-based nickel sulfide electrodes showing excellent electrochemical response are attractive for energy storage devices.