Graphene-based nanohybrid paper as high-performance freestanding electrode for flexible supercapacitor applications

Abstract

We have developed a new type of flexible nanohybrid paper based on growth of nanostructured transition metal oxides or conductive polymers on multilayered graphene paper and explored its practical application as free-standing electrode for flexible energy storage devices.Flexible energy storage devices have triggered significant research efforts for their potential applications in portable electronic devices including roll-up display, electronic paper, distributed sensors, stretchable integrated circuits, wearable multimedia computing, and military missile systems. In particular, flexible supercapacitors (SCs) with large power density, moderate energy density, good operational safety and long cycling life are highly desirable as a modern energy storage system. Graphene has emerged as a new class of two-dimensional carbon nanostructure and holds great promise in electrochemical applications because of the unprecedented combination of high electrical and thermal conductivities, good transparency, great mechanical strength, inherent flexibility and huge specific surface area. More importantly, graphene can be produced in large scale at very low cost. Our results have shown that graphene or graphene oxide sheets can be assembled into paper-like structure with excellent flexibility, mechanical stiffness, and exceptional electrical conductivity, which make them promising as high-performance flexible electrode for SCs application. Furthermore, in order to improve the surpercapacitive properties of the freestanding graphene paper, we developed a hybrid SC electrode by combining the graphene paper and the redox active materials of transition metal oxides (MnO2) and conductive polymers (polyaniline). The obtained multilayered nanohybrid paper electrode exhibited an enhanced surpercapacitor performance such as high specific capacitance, good rate capability and cycling stability. These features collectively demonstrated the potential of graphene-based nanohybrid paper as high-performance electrode to realize high-energy density and high-power density characteristics for flexible electrochemical capacitor applications.