All-solid-state flexible thin-film supercapacitors with high electrochemical performance based on a two-dimensional V2O5·H2O/graphene composite

Abstract

With the rapid development of portable electronics, all-solid-state thin-film supercapacitors (ASSTFSs) have attracted tremendous attention and been considered as competitive candidates owing to their ultraflexibility and high safety. The major challenge in ASSTFSs is the low capacity and energy density due to the lack of proper electrode materials with high conductivity and surface area. In this study, we develop a nanocomposite electrode combined with pseudocapacitive vanadium pentoxide and highly conductive graphene with ultrathin thickness for the application of ASSTFSs. The novel structure of the nanocomposite achieves maximal integration of both the merits of each component with high conductivity and ultrathin thickness, which enhances the electron transfer, shortens the ion diffusion paths and increases the electrode–electrolyte contact in ASSTFSs, leading to high electrochemical performance. The as-fabricated ASSTFS achieves a high areal capacitance of 11 718 μF cm⁻², a remarkable energy density of 1.13 μW h cm⁻² at a power density of 10.0 μW cm⁻² and long-term cycling stability for 2000 cycles, demonstrating the superior electrochemical performance and rendering it a promising candidate for portable electronics.