A Flexible All-Solid-State Asymmetric Supercapacitor Based on a Nanocomposite of Vanadium Oxide/Graphene and Polyaniline Hydrogel with Excellent Operational Stability and Energy Density

Porous polymer-based materials of high electrical conductivity are essential for a wide range of applications. An innovative nanocomposite of V₂O₅/rGO/polyaniline hydrogel (VG/PANi-HG) was synthesized using in situ oxidative polymerization in the presence of V₂O₅/rGO (VG) and phytic acid on a carbon fiber substrate. Subsequently, the corresponding electrode was employed as a flexible free-standing electrode and examined through a range of electrochemical methods to assess its performance in high-rate supercapacitors. The VG/PANi-HG supercapacitor demonstrated an excellent specific capacitance of 982 F g^-1 at a current density of 2.7 A g^-1. Furthermore, an asymmetric all-solid-state (ASC) device was assembled using VG/PANi-HG as a positive electrode in combination with a graphene oxide electrode as a negative electrode and a polyvinyl alcohol (PVA) hydrogel electrolyte. This flexible asymmetric device exhibited an impressive cycle life stability and a power density of 2 kW kg^-1 at an energy density of 29.44 Wh kg^-1. Our results reveal that the VG/PANi-HG electrode material is a promising candidate for future electrochemical energy storage devices.