Influence of geometry-induced current and potential distributions on the characterization of constant-phase element behavior

Abstract

Electrode geometry is abruptly truncated at the metal insulating boundary. A theoretical analysis has shown that disk-electrode geometry induces current and potential distributions that influence the impedance response in the high frequency domain. In this paper we investigate the extent of this influence on an experimental system displaying constant-phase element (CPE) behavior. We shall focus on the influence of these current distributions on the characterization of underlying CPE behavior from the analysis of the imaginary part of the impedance, although we shall also address results obtained from the complex non-linear fitting of impedance data to an equivalent circuit. The crossover from CPE behavior to this geometry-dominated regime establishes an upper cutoff in the experimental frequency range employed to characterize CPE response. We discuss the experimental conditions for which this crossover may prevent the analysis of experimental results to reveal the real underlying CPE behavior. The results and conclusions here obtained agree with previous theoretical modeling. Taking into account the limitations presented here can help to a better characterization and a deeper understanding of the frequency dispersion in the response of solid electrodes.