  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 (PNP) or anomalous (PNPA) 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
