Investigation of elektrochemical energy storage properties of reduced graphene oxide/polypyrrole electrode

In this study, PPy and PPY/rGO composite materials were synthesized via the electrochemical deposition method on stainless steel surfaces. Graphene oxide (GO) was synthesized by using the Hummer's method. Structural characterizations were worked with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier-transformation infrared (FTIR) spectroscopy. The cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods were used to determine electrochemical energy storage properties and to calculate capacitance values of electrodes. The highest specific capacitances of 104.22 F/g at 10 mV/s and 171.99 F/g at 6 A/g are determined for the PPy film. The maximum specific energy was obtained 116.67 Wh/kg at 6 A/g and the maximum specific power was obtained 8888.89 W/kg at 15 A/g for the PPy film. It was determined that the PPy electrode retained 59.5% of its capacitance value after 4000 cycles. The highest specific capacitances of 122.53 F/g at 10 mV/s and 313.26 F/g at 6 A/g are determined for the PPy/rGO film. The maximum specific energy was obtained at 212.5 Wh/kg at 6 A/g and the maximum specific power was obtained at 13026.32 W/kg at 15 A/g for the PPy/rGO film. It was determined that the PPy/rGO electrode retained 97.6% of its capacitance value after 4000 cycles. The acceptor densities of the films were found as 8.75x1015 cm-3 and 1.98x1016 cm-3 for the PPy and PPy/rGO films, respectively. The appropriate equivalent circuits for electrodes were suggested from impedance measurements. The results showed that the produced PPy/rGO electrodes are promising materials for supercapacitor applications.