The Research Of Graphene Based Flexible Supercapacitor Electrode Materials And Devices

For the past few years, with the continuous development of wearable electronics, flexible energy storage devices have roused intensive concern and extensive research among the researchers. As one of the most important functional components in wearable electronics, flexible energy storage devices have a wide application prospect. Among which, flexible supercapacitors have been widely studied due to its high energy storage efficiency, long cycle life and costless. The working circumstance of wearable electronics requires secure, portable and high capacity energy storage devices. And the energy storage properties and practicability of supercapacitors are influenced by electrode materials, electrolyte and device configurations. In this paper, we have prepared a series of high performance graphene based electrode materials and flexible supercapacitors. And the relationship between electrode materials, electrolyte, device configurations and supercapacitor performance were systematically studied. Furthermore, we also preliminarily investigated the feasibility of integrating these devices into wearable electronics.The research content of this thesis is as follows:(1) We demonstrate a convenient graphene film preparation method, which combine the graphene oxide reduction and film formation process together. Through which high conductivity, large-area flexible graphene film can be prepared in a short time. Supercapacitors based on this graphene film exhibit high capacitance, long cycle life and outstanding flexibility. We have investigated the influence of electrode thickness and device area upon the supercapacitor performance. Furthermore, high performance all-solid supercapacitor was established by employing graphene film electrode material and polymer electrolyte.(2) We have prepared a lightweight, conductive and electrochemically active reduced graphene oxide/cotton fiber(r GO/CF) composite film by introducing graphene nanosheets into cotton fabrics. Flexible supercapacitors based on r GO/CF composite film exhibit high capacitance. Furthermore, we have proposed a new sandwich-interdigital device structure, which can increase the electrode/electrolyte contact area to a large extent, so as to improve supercapacitor performance remarkably.(3) To develop implantable flexible supercapacitors, we employ cotton fiber as skeleton, graphene hydrogels/muti-walled carbon nanotubes(GHs/MWCNTs) composites as active materials to prepare one-dimensional flexible electrode. Flexible fiber-shaped supercapacitors based on GHs/MWCNTs-CF and all-solid electrolyte exhibit high performance, exceptional mechanical property and outstanding electrochemical stability. Besides, we have preliminarily investigated the feasibility of integrating these devices into wearable electronics.