Measurements of PEM conductivity by impedance spectroscopy

The methodology of PEM conductivity measurements is discussed for examples of literature data and results of the experiments, carried out in this study. It is shown here that a simple two-electrode cell proposed in this work, operated at frequencies of 1 to 10(7) Hz reproducibly gives a response typical for a solid electrolyte, and therefore is easily rationalised in terms of equivalent Circuits. The obtained impedance diagrams are compared with the ones described in the literature for 4-probe experiments. It appears from this comparison that the cell geometry and electrode arrangement play important roles in the formation of the frequency dependent response. In some cases, two-electrode cells may have an advantage over the four-probe technique, as they are less complicated and therefore involve less stray effects ill the resulting impedance spectra. In this study, the proposed configuration, which we have previously utilized for some of our measurements, proved to be efficient at producing reproducible, reasonable and reliable results, related to the expected values of PEM conductivity. (c) 2008 Elsevier B.V. All rights reserved.