New electrode active materials for supercapacitors: Pencil graphite electrode coated with cobalt ion doped poly(3-methylthiophene) and poly(3,4-ethylenedioxythiophene)

• Co2+ doped polymer films were synthesized on PGE by cyclic voltammetry.
• The doped polymer coated electrodes were characterized by electrochemical methods.
• Results show that electrodes can be suggested using for supercapacitor active material.

In this study, electrochemical characterization of cobalt ions (Co2+) doped poly(3-metylthiophene) (P3MeT:Co) and poly(3,4-ethylenedioxythiophene) (PEDOT:Co) films on pencil graphite electrode (PGE) has been reported as a new electrode active material for supercapacitor applications. P3MeT:Co and PEDOT:Co films have been synthesized onto PGE by using cyclic voltammetry (CV) method. The surface characterization of the electrodes (PGE/P3MeT:Co and PGE/PEDOT:Co) has been studied by means of scanning electron microscopy (SEM). Electrochemical properties of the electrodes have been investigated by using different electrochemical methods, including CV, electrochemical impedance spectroscopy (EIS) and repeating chronopotentiometry (RCP). Electrochemical performance of real supercapacitors has been tested using galvanostatic charge–discharge method. Specific capacitance of the electrodes has been calculated using CV and EIS methods. The results obtained from CV and EIS have shown that PGE/P3MeT:Co has much higher specific capacitance than that of PGE/PEDOT:Co. According to CV measurements, PGE/P3MeT:Co and PGE/PEDOT:Co have shown the maximum specific capacitance of 131.99 and 112.64 F g−1 at 10 mV s−1, respectively. The long term charge–discharge cycling stabilities of the electrodes have been investigated by using RCP method. RCP measurements have indicated that electrodes can be used as an electrode active material for supercapacitor applications. Specific powers (SP) of PGE/P3MeT:Co and PGE/PEDOT:Co have been found to be as 7350.00 and 9060.00 W kg−1, respectively.