Study on preparation and performance of flexible all-solid-state supercapacitor based on nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes /manganese dioxide

Abstract A facile two-step synthesis method was developed to prepare nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes/manganese dioxide (NGC/MnO2) fiber electrode for flexible all-solid-state supercapacitors. Firstly, the NGC fibers were prepared through hydrothermal method, and then NGC/MnO2 fibers were obtained by a redox reaction with different reaction times (0.5-2.5 h). The NGC/MnO2-2h fiber electrode exhibited a larger specific capacitance of 367.7 F cm-3 at a current density of 0.5 A cm-3 and an excellent cycling stabilty. A flexible all-solid-state supercapacitor device was obtained through two parallel-arranged NGC/MnO2-2h electrodes coated with PVA-LiCl gel electrolyte. The flexible all-solid-state supercapacitor exhibited a high energy density of 5.9 mWh cm-3 and a good cycling performance. Moreover, the supercapacitor showed excellent flexibility properties, which is advantageous for its application in flexible energy storage devices.