Improving the volumetric specific capacitance of flexible polyaniline electrode: solution casting method and effect of reduced graphene oxide sheets

Abstract

High volumetric specific capacitance is essential for flexible supercapacitors. In this paper, a flexible composite electrode with ultrahigh volumetric specific capacitance and good rate performance is designed and prepared. The film electrode is composed of non-porous compact polyaniline as the matrix and a small amount of reduced graphene oxide sheets as the conductive filler. The film is prepared by a newly developed solution casting method, where the casting solution is obtained by self-assembly of polyaniline and graphene oxide in a blended solution. A systematical investigation on the effect of reduced graphene oxide sheets reveals that they serve as both the conductive filler and the diffusion barrier. With the optimized reduced graphene oxide content, a large volumetric specific capacitance of 1354 F cm−3 at 2.4 A cm−3 is achieved, and good rate performance is also obtained because of the good ionic conductivity of polyaniline. This work provides a high-performance electrode for flexible supercapacitors, and the solution casting method is also valuable in fabricating other organic electrode materials.