Revisiting the analysis of impedance data for double layer capacitance

A method was developed to extract double layer capacitance (C-dl) from data displaying time constant dispersion at a frequency where the phase angle reached its maximum (f(1)). This method was implemented in a set of synthetic data and the Kramers-Kronig (K-K) transformable experimental data for mild steel in an acidic solution. The double layer capacitance values were compared with ones extracted from the constant phase element (CPE) parameters, Y-o and alpha, at a frequency where the imaginary part of the impedance reached its maximum (f(2)). A significant closeness of the results was reached for two different frequencies.