ZnS–Ni<sub>7</sub>S<sub>6</sub> Nanosheet Arrays Wrapped with Nanopetals of Ni(OH)<sub>2</sub> as a Novel Core–Shell Electrode Material for Asymmetric Supercapacitors with High Energy Density and Cycling Stability Performance
Ghuzanfar Saeed, Parthasarathi Bandyopadhyay, Sachin Kumar, Nam Hoon Kim, Joong Hee Lee
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.