Electrochemically induced ageing of polyaniline. An electrochemical impedance spectroscopy study

In this work it is shown that the impedance response of polyaniline during the electrochemically induced ageing, changes with time. The results are analysed in terms of a simple equivalent circuit which parameters change linearly with the logarithm of the ageing time. As proposed earlier, this dependence can be explained by considering that the ageing kinetics is of the Roginskii–Zeldovich or Elovich type. It is proposed that the changes in the impedance response could be associated to the decrease of the electrochemically active area of the polymer/electrolyte interface.

► The EIS response of polyaniline is measured during its ageing process.
► During the ageing process the impedance parameters change.
► These variations imply a contraction of the polymer film.
► The changes in Rct and 1/Y0 follow a self-inhibitory kinetics.