Facile synthesis of hybrid electrode materials based on RGO.Ag/Co for an efficient symmetric supercapacitor

Abstract

• Preparation and investigation of a new nanostructure hybrid composite material for supercapacitor electrodes. • Surface morphology and electrochemical performances of graphene, silver and the doping were analyzed. • Fabrication of full cell supercapacitor based on the hybrid electrode. • The hybrid composite electrode with doping is the key for enhancing all electrochemical analysis. This wok demonstrates a facile synthesis approach of advanced nanostructure composite electrode based on silver decorated reduced graphene oxide doped with various mass loading of cobalt nanostructure (1%, 5%, and 10%) for achieving a promised progress in the wide applications of supercapacitors. Symmetric electrodes were prepared by a simple and cost-effective hydrothermal approach in which the doped cobalt nanostructure plays an important role in the development of super capacitance electrodes. The as-synthesized composite structure, morphology, and surface area were investigated using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Brunauer–Emmet–Teller (BET). The fabricated electrodes were electrochemically tested in 3 M KOH as strong alkaline electrolyte within a Swagelok test cell assembly using Bio-Logic VSP-300 where the highest specific capacitance obtained on the (5%) sample was 567.04 F g −1 at a scan rate of 5 mv s −1 while the high energy density and power density were 69.16 Wh kg −1 and 200 W kg −1 , respectively at the current density of 0.1 A g −1 coupled with retention of 89.36% after 2000 cycles at 2 A g −1 . On the other hand, the specific capacitance of the 10% sample decreased to 450.88 F g −1 at a scan rate of 5 mv s −1 while the energy and power densities obtained were 57.83 Wh kg −1 and 200 W kg −1 at 0.1 A g −1 . It was found that the excessive mass loadings of Co nanostructure causes the electrochemical series resistance (ESR) to increase due to obstructions insertion for ion diffusion along with the electrode-electrolyte interface, thus, reducing the electrochemical performance of the supercapacitor.