21 - Graphene/polymer composite application on supercapacitors

Abstract

Recently, supercapacitors have grabbed the attention of researchers as potent energy storage devices due to their enhanced cycle life, fast charge/discharge rate, and power efficiency. A supercapacitor’s current use lies in the start and stop operations of the regenerative braking system of electric vehicles, tramways, and short-distance electric drive. Other than this, due to the high-power capability of supercapacitors, they are used in various other applications such as power backup systems and portable devices. Depending on the charge storage mechanism, they are classified as electrical double-layer capacitors (EDLCs) and pseudocapacitors (PCs). EDLCs involve the accumulation of charge carriers through adsorption and desorption at the electrode/electrolyte interface while PCs involve redox reactions near the electrode surface. The electrodes used in EDLCs consist of carbon-based material such as activated carbon (ACs), mesoporous carbon, and carbon nanotubes as they provide good control on porosity, pore volume, and pore size distribution. As EDLCs undergo adsorption and desorption, they deliver high-power density and good stability. Pseudocapacitive electrodes are made up of metal oxides or conducting polymer-based materials that offer high specific capacitance and energy density due to fast redox reactions. To fabricate a supercapacitor offering high specific capacitance along with good stability is to employ EDLCs and PCs together in a single device by developing hybrid composites. In hybrid composites, carbon-based materials are employed together with either metal oxides or conducting polymers to utilize the advantages of both types.