Method for extracting kinetic parameters from measured impedance spectra

✍ Scribed by P. Kurzweil; J. Ober; D.W. Wabner

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 599 KB
• Volume: 34
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(89)87155-5

✦ Synopsis

The necessity for extracting faradaic impedances from measured ac impedance spectra is discussed. A straightforward extrapolation method is described which allows the separation of faradaic impedances from measured spectra. Perturbations like solution resistances, inductivities and double-layer capacitances are extracted step by step to obtain the frequency dependence of the purely faradaic part of the impedance, which can now be analysed separately, for example, by using the same method again.

This approach provides electrolyte and polarization resistances as well as charge transfer resistances and other important values of electrode kinetics. The method can be applied to systems exhibiting two or more time constants.

A new type of diagram to depicting impedance spectra is introduced. Examples are presented to illustrate the use of separating farad& impedances for the analysis of ac impedance spectra.