Construction of MWCNT/ZnS/NiS microspheres: Unveiling enhanced electrochemical performance for aqueous asymmetric supercapacitor

Abstract

The fabrication of suitable electrode materials is crucial to improve the electrochemical performance of super- capacitors. This work reflects the electrochemical performance of ZnS/NiS and MWCNT/ZnS/NiS composites prepared by simplest and powerful hydrothermal method for supercapacitor application. The synthesized materials are scientifically investigated through various characterization tools. The electrochemical characteristics are investigated by CV, GCD and EIS techniques. Owing to the connectivity of ZnS/NiS microspheres through multi-walled carbon nanotubes (MWCNTs), the high capacitance of 2267 F g- 1 is obtained from MWCNT/ZnS/ NiS composite at 1 A g- 1. The capacitance of MWCNT/ZnS/NiS composite is found to be higher from ZnS/NiS (1693 F g- 1), ZnS (853 F g- 1) and NiS (1127 F g- 1). Further, the aqueous asymmetric supercapacitor (ASC) is constructed by MWCNT/ZnS/NiS (+ve electrode) and AC (-ve electrode) i.e. MWCNT/ZnS/NiS//AC which demonstrates the high energy density of 40.37 W h kg- 1 at 775 W kg- 1. Moreover, four yellow color light emitted diodes (LEDs), a toy motor fan and a kitchen timer are electrically operated separately by series connected two MWCNT/ZnS/NiS//AC ASC devices. Owing to the superior energy storage performance, MWCNT/ ZnS/NiS nanocomposite may be considered as a promising candidate for future possibilities of generating high energy density as hybrid energy storage material.