Poly(3,4-ethylenedioxythiophene) electrode grown in the presence of ionic liquid and its symmetrical electrochemical supercapacitor application

Poly(3,4-ethylenedioxythiophene) polymer film (PEDOT-IL) was electrosynthesized in the ionic liquid (IL) 1-ethyl-3-methylimidazolium hydrogen sulphate (EMIMHSO 4 ) medium, which also contains 0.1 M LiClO 4 in ACN. For comparison reasons in terms of structure and electrode capacitance performance, PEDOT film was also synthesized electrochemically without IL. The SEM results show that PEDOT-IL film has more porous surface and fine textures with nanometer-diameter than PEDOT polymer. Different electrochemical methods including galvanostatic charge–discharge (CD) experiments, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were carried out to investigate the applicability of the system as a redox supercapacitor for both polymers. PEDOT-IL electrode shows higher optimum specific capacitance than PEDOT film. Additionally, the symmetrical supercapacitor was assembled from two PEDOT-IL electrodes in LiClO 4 /ACN medium and exhibited a maximum specific capacitance of 107 F g −1 , an energy density of 11.5 Wh kg −1 at a power density 13 kW kg −1 , and an excellent cycle life of 96% specific capacitance retention after 1000 cycles.