Impedance Spectroscopy Study of the PEM Fuel Cell Cathode with Nonuniform Nafion Loading

We report modeling and experimental study of impedance of the PEM fuel cell cathode with nonuniform ionomer loading. A physics–based model for the high–frequency impedance is developed and analytical solution for impedance is derived. Assuming that the CCL proton conductivity σ p exponentially decays from the membrane surface, we fit the model to experimental spectra of the cell measured at the open circuit conditions. Fitting gives the characteristic scale of the σ p decay, the average CCL proton conductivity and the double layer capacitance.