Nitrogen-doped reduced graphene oxide intertwined with V2O3 nanoflakes as self-supported electrodes for flexible all-solid-state supercapacitors

Abstract

Flexible all-solid-state supercapacitors (SCs) have great potential applications in flexible and wearable electronics because of their safety, high power density, flexibility, and portability. Herein, a self-supported film electrode comprising nitrogen-doped reduced graphene oxide intertwined with vanadium trioxide nanoflakes (V₂O₃/N-rGO) was fabricated. The V₂O₃ nanoflakes have abundant active sites accessible to charge storage, and nitrogen-doped reduced graphene oxide provides a flexible support. The V₂O₃/N-rGO film electrodes exhibit high conductivity, short diffusion length for ions and electrons, and robust flexibility, resulting in excellent capacitive properties and flexibility. The flexible V₂O₃/N-rGO film electrode has a high areal capacitance of 216 mF cm⁻² at a current density of 1 mA cm⁻². All-solid-state flexible SCs assembled by sandwiching two self-supported V₂O₃/N-rGO hybrid electrodes with alkaline poly(vinyl alcohol) (PVA) and LiCl gel electrolyte show an ideal volumetric capacitance of 8.1 F cm⁻³, an energy density of 0.55 mW h cm⁻³, and a power density of 0.035 W cm⁻³ at a current density of 0.1 A cm⁻³, based on the entire cell. This indicates that the self-supported V₂O₃/N-rGO film electrodes have great potential applications in portable and wearable flexible electronics due to their high capacitance, high energy/power density, and good mechanical flexibility.