From frequency dispersion to ohmic impedance: A new insight on the high-frequency impedance analysis of electrochemical systems

The increasing use of impedance for the characterization of an electrified interface is accompanied by the development of accurate models to analyze the results. In the present work, the concept of ohmic impedance is revisited using both numerical simulations and experimental results. The Havriliak-Negami equation is shown to provide a good representation of the high-frequency dispersion or complex ohmic impedance associated with the disk electrode geometry. An excellent fit to simulated complex ohmic impedance was found for both capacitive electrodes and for electrodes characterized by constant-phaseelement behavior. The use of the Havriliak-Negami equation to account for the complex ohmic impedance was shown to extend the useful frequency range for regression of physical models to the impedance response for three experimental systems: a gold electrode in a 0.1 M sodium sulfate solution, an aluminum electrode in a 0.01 M sodium sulfate solution, and pure iron in a 0.5 M sulfuric acid solution. (C) 2019 Elsevier Ltd. All rights reserved.