Electrochemical impedance spectroscopic studies on aging-dependent electrochemical degradation of p-toluene sulfonic acid-doped polypyrrole thin film

The conducting polymer polypyrrole thin film was galvanostatically polymerized on stainless steel substrate for the supercapacitor electrode. The electrochemical stability of the electrode was monitored each 30 days of aging up to 90 days. The FTIR analysis showed an increase in intensity of the absorption peaks, especially high growth of the carbonyl peaks after 90 days of aging. The electrochemical capacitance degradation of the electrode was studied using cyclic voltammetric and galvanostatic charge/discharge analysis in 1 M Na2SO4 electrolyte, which showed similar to 53% of fading in the initial specific capacitance value after 90 days. Further, the electrochemical degradation of polypyrrole electrodes was analyzed in detail using electrochemical impedance spectroscopy. The analysis showed a large increase in the internal resistance and low-power deliverability of the electrode with respect to aging as the main reasons for the degradation of specific capacitance of the polypyrrole electrode.