Improved electrochemical performance of hydrothermally synthesized Zn-Ni-S/rGO nanocomposite as an electrode for supercapacitor application

Abstract

This present work reports on the hydrothermal synthesis of zinc-nickel sulfide with reduced graphene oxide (Zn-Ni-S/rGO) nanocomposite for supercapacitor applications. The synthesized samples are evaluated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), and high-resolution scanning transmission electron microscopy (HR-TEM), which are employed to examine the structure, morphology, and chemical composition of the Zn-Ni-S/rGO nanocomposite. The XRD results indicates the presence of high crystalline Zn-Ni-S with rGO. FE-SEM equipped with an EDX spectrum, illustrates a spherical morphology of Zn-Ni-S combined with a thin layer of rGO in the form of composite nature. Furthermore, the elemental composition of Zinc, Nickel, Sulfur and Carbon presence in the EDS spectra further supports the formation of the Zn-Ni-S/rGO nanocomposite. The electrochemcial properties of ZnS and the Zn-Ni-S/rGO nanocomposite are studied through cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. A high specific capacitance of 284F/g is obtained at 11 mA g−1 current density. The Zn-Ni-S/rGO nanocomposite demonstrates exceptionally high capacitance retention of 96 % over 3,000 charging and discharging cycles. The potential application of the Zn-Ni-S/rGO nanocomposite as an efficient electrode material for pseudocapacitors is supported by its favourable performance.