Practical considerations regarding the measurement of ionic conductivity by EIS in conductive polymers [articol]

Abstract

Electrochemical Impedance Spectroscopy (EIS) is a powerful technique for the evaluation of ionic conductivity in conductive polymers used for PEM electrolysers/fuel cells or for other purposes. Although this technique is a very well established one, the determination includes compulsory the thickness of the membrane (this varies with the relative humidity, water uptake, membrane batch etc.), and hence a series of errors, often incurred due to a crude determination of membrane thickness or due to various factors that determines the modification of membrane thickness during the experimental determination of EIS spectra. The paper discusses various measures that may contribute to enhance the precision of thickness determination, presents a novel cell (used in a two-electrode or three-electrode configuration) that has the advantage of allowing a precise determination of the membrane thickness (at micrometer resolution) during the determination of the electrochemical impedance spectra and discusses the effect of various parameters on EIS measurements.