A model for concentration impedance of a PEM fuel cell

We report an analytical physics–based model for oxygen concentration perturbation spectra of a PEM fuel cell cathode side. An expression for the concentration impedance (CI) taking into account oxygen transport in the cathode catalyst layer (CCL) and the gas diffusion layer (GDL) is derived. In the static limit the CI gives the limiting current density due to oxygen transport in the GDL. The Bode plots of real and imaginary part of the CI have minima at the characteristic frequencies corresponding to oxygen transport in the GDL and the CCL, respectively. These features enable direct estimation of the respective oxygen diffusion coefficients without curve fitting.