Electrochemical properties of polypyrrole in nonaqueous solutions

Abstract

The electrochemical properties of polypyrrole (pPy) films of various thickness, galvanostatically deposited on a Pt anode, have been studied in solutions of LiClO 4 (1.0 M) in propylene carbonate (PC) by employing the cyclic voltammetric technique. The experimental results have been interpreted on the basis of the model developed for intercalation electrodes. The pPy films were found to have reproducible behaviour. The charge transport through the polymer internal volume of the film is a composite process of electron hopping in conjunction with counterion, polymer chain and solvent motion, driven by the effective electrochemical potential. The kinetics of oxidation (doping) and reduction (undoping) reactions in the pPy films were found to be limited by ionic flow into the polymer phase. Active mass utilization decreases with increasing the film thickness and with increasing potential sweep rate, meaning that the electrochemical conversion of the whole film becomes incomplete and only a fraction of the polymer layer takes part in the doping-undoping process. The experimental results proved to be useful to optimise a pPy electrode when utilizing it as the cathode active material of a rechargeable lithium battery.