A quasi three-dimensional model for PEM fuel cell impedance: The effect of local oxygen depletion under the flow field rib

Our previous 1d+1d model for PEM fuel cell impedance is extended to take into account 2d distribution of the oxygen concentration in the gas-diffusion layer under the flow field channel and rib. Fitting of the model impedance to the experimental spectra from the segmented PEMFC shows that in spite of nearly uniform GDL oxygen diffusivity, local oxygen concentration and current density exhibit strong decay under the rib (land). The effect is merely due to larger oxygen transport distance under the rib. The results demonstrate validity of local EIS for measuring 3D distribution of local current in an operating PEM fuel cell.