Capacitance behaviors of EDOT and pyrrole copolymer, and equivalent circuit model

Abstract

In this paper, a copolymer of 3,4-Ethylenedioxythiophene (EDOT) and pyrrole (Py) were electrochemically synthesised on glassy carbon electrode by cyclic voltammetry (CV). The modified electrodes were characterised by CV, Fourier transform infrared-Attenuated total reflectance, scanning electron microscopy, energy dispersion X-ray analysis, galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS) and stability measurements. Capacitor performances of polypyrrole (PPy), poly(3,4-ethylenedioxythiophene (PEDOT), and poly(3,4-ethylenedioxythiophene-co-pyrrole) (P(EDOT-co-Py)) films were comparatively studied in 0.5 M H2SO4 solution. In addition, the experimental and theoretical data of EIS were simulated by the equivalent circuit model of Rs(Cdl1(R1(QR2)))(Cdl2R3). The highest specific capacitances of PEDOT, PPy and P(EDOT-co-Py) films were obtained as Csp = 85, 63 and 89 mFcm−2, respectively. The highest double-layer capacitance and phase angle (θ) were obtained as Cdl = 0.43 mFcm−2 and θ = 73.1° for initial feed ratio of [EDOT]0/[Py]0 = 1/50, respectively. The capacitive results of copolymers are promising electrode materials for high-performance electrical energy storage devices.