ZnS-Ni7S6 Nanosheet Arrays Wrapped with Nanopetals of Ni(OH)2 as a Novel Core-Shell Electrode Material for Asymmetric Supercapacitors with High Energy Density and Cycling Stability Performance.

Abstract

Supercapacitors possess minimum energy density, lower rate capability, and inferior long-term cycling stability performance, and these issues have restricted their practical applications. In these circumstances, supercapacitors based on a new class of hybrid nanomaterial are strongly desirable. Herein, for the first time, a complex nanoarchitecture comprised of a ZnS-Ni7S6/Ni(OH)2 core/shell is constructed via a multistep hydrothermal process. The ZnS-Ni7S6/Ni(OH)2 core/shell nanoarchitecture illustrates a commendable areal capacitance of 13.55 F cm-2 at a lower current density value of 5 mA cm-2, respectively. The ZnS-Ni7S6/Ni(OH)2 core/shell hybrid nanomaterial maintains a high cycling stability performance of 95.12% after a maximum 10 000 number of cycles. Moreover, the asymmetric supercapacitor device made up of ZnS-Ni7S6/Ni(OH)2 and nitrogen-sulfur-codoped graphene nanosheets (NSGNs) delivers an ultrahigh energy density value of 68.85 W h kg-1 at a power density of 700.16 W kg-1. The cycling stability of the ZnS-Ni7S6/Ni(OH)2//NSGN asymmetric supercapacitor was performed and was 91.79% after 10 000 GCD cycles. The ZnS-Ni7S6/Ni(OH)2 core/shell hybrid electrode material has helped in promoting an asymmetric supercapacitor device with an elevated performance and can be considered as a potential electrode material to develop energy storage devices in the future.