Zinc Cobalt Sulfide/Reduced Graphene Oxide Nanocomposite for High‐Performance Asymmetric Supercapacitor: A Microwave‐Assisted Synthesis

Abstract

In this work, the microwave‐assisted synthesis of ZnxCo1–xS/reduced graphene oxide (rGO) nanocomposite and the evaluation of its electrochemical properties for supercapacitor (SC) application are dealt with. The synergistic effect between ZnxCo1–xS and rGO along with the conducting network provided by rGO facilitates the conducive movement of ions and enhances the electrochemical performance of the nanocomposite. The stoichiometric ratio of Zn:Co:rGO plays a crucial role in the SC behavior of the material. In three electrode systems, a material shows a high specific capacitance of 1094 F g−1 at current density 1 A g−1. The material stores charge both diffusively as well as capacitively. An asymmetric SC with acetylene black as the negative electrode and ZnxCo1–xS/rGO as the positive electrode has a stable potential window 0–1.6 V. For the fabrication of the electrodes, Ni foam is used as the current collector. The energy density and power density of the SC are found to be 32.71 and 431.95 W kg−1, respectively. The Coulombic efficiency of the SC is found to be 107% while its capacitance retention is 86% after 10 000 galvanostatic charge–discharge cycles. The energy and power density of the SC are comparatively higher than many recently reported literature. The material exhibits superior electrochemical stability and reversibility and can be a suitable electrode material for SCs.