Facile synthesis of graphene-Zn3V2O8 nanocomposite as a high performance electrode material for symmetric supercapacitor

In order to improve the energy density of the supercapacitor, fabrication of next-generation materials with inimitable morphology and superior electrochemical performance is highly desired. Herein, a novel hybrid electrode material, namely graphene-Zn3V2O8 nanocomposites, were successfully prepared via facile solvothermal process followed by thermal annealing treatment. Graphene sheets were synthesised through the eco-friendly liquid phase exfoliation approach with optimised ethanol to water volume ratio (2:3). Optimisations on the weight ratio between the graphene and Zn3V2O8 were performed to determine the synergistic effect between them. The morphogenesis of the graphene-Zn3V2O8 nanohybrid manifests sheet on sheet nanostructures that intertwined with each other to form a 3D network architecture, which provides sufficient electroactive sites and shortens the ions diffusion pathway, leading to eminent electrochemical properties. The electrochemical properties of these materials were evaluated by cyclic voltammetry and galvanostatic charge-discharge tests in 2 M KOH aqueous electrolyte. Among the nanocomposites studied, G-3ZVO (weight ratio of 1:3) exhibited a specific capacitance of 564 Fg(-l) at 0.8 Ag-1, outstanding rate capability and good cycling stability even after 5000 cycles. Furthermore, this symmetrical supercapacitor delivered an impressive energy density of 78 Wh/kg at power density of 75.5 kW/kg. (C) 2019 Elsevier B.V. All rights reserved.