2.0-V flexible all-solid-state symmetric supercapacitor device with high electrochemical performance composed of MWCNTs-WO3-graphite sheet

Abstract

Simple and scalable fabrication of 3D nanostructure MWCNTs-WO3-graphite sheet with favorite flexibility and excellent mechanical strength is demonstrated. The flexible sheet was fabricated by employing second-hand and waste graphite electrodes through uniform adding of Zn nanoparticles (ZnNPs) into matrix of multi-walled carbon nanotubes-tungsten oxide-graphite sheet followed by selective dissolving of ZnNPs from the sheet. The fabrication condition of the MWCNTs-WO3-graphite sheet was optimized for its application in flexible supercapacitor device. The MWCNTs-WO3-graphite sheet exhibited attractive electrochemical behaviors including a low ohmic drop and a high areal capacitance of 114 mF cm−2 (103 F g−1) at 1.7 mA cm−2 (1.5 A g−1) in aqueous 1.0 M H2SO4 electrolyte. All-solid-state symmetric supercapacitor device based on flexible MWCNTs-WO3-graphite sheets showed a high energy density of 57 μWh cm−2, a high operation potential of 2.0 V, and significant cycling stability with 96% areal capacitance retention after 2000 continuous cycles.