The Kramers–Kronig relations for usual and anomalous Poisson–Nernst–Planck models

The consistency of the frequency response predicted by a class of electrochemical impedance expressions is analytically checked by invoking the Kramers?Kronig (KK) relations. These expressions are obtained in the context of Poisson?Nernst?Planck usual or anomalous diffusional models that satisfy Poisson?s equation in a finite length situation. The theoretical results, besides being successful in interpreting experimental data, are also shown to obey the KK relations when these relations are modified accordingly.