Flexible Solid‐State Symmetric Supercapacitors Using H_xWO₃@Reduced Graphene Oxide Composite with High Volumetric Energy and Power Densities

Abstract

Abstract We have synthesized hydrogen tungsten oxide decorated reduced graphene oxide (H x WO 3 @rGO) composite with different precursor weight ratios of WS 2 and GO, of which the WG1‐2 system, produced from WS 2 and GO in the 1 : 2 weight ratio by treatment with hydrogen peroxide followed by hydrothermal treatment, shows high areal capacitance of 409 mF cm −2 at 1 mA cm −2 current density with retention of 61.4 % at 20 mA cm −2 current density. This H x WO 3 @rGO composite is drop‐cast onto graphite layer‐coated on scotch tape to design a flexible supercapacitor. The flexible solid‐state symmetric supercapacitor based on the WG1‐2 composite shows a high volumetric capacitance of 3.56 F cm −3 and ultrahigh energy density of 1.6 mW h cm −3 at 1469.43 mW cm −3 power density.