A Fast Recurrent Model for High-current PEM Fuel Cell Impedance

Abstract

A novel method for calculation of PEM fuel cell cathode impedance from charge and mass conservation equations is developed. The cathode catalyst layer is separated into N sub–layers. Assuming that the steady–state variables along the sub–layer are constant, linearized and Fourier–transformed problem for the overpotential and oxygen concentration perturbations is solved analytically on a single sub–layer. The solution leads to recurrent formulas expressing the perturbation amplitudes on the left side of the sub–layer through the values on its right side. Starting from the CCL/GDL interface, N–fold application of the recurrent relations gives the parameters at the membrane surface, leading to the system impedance. Comparison of impedance spectra obtained using this technique with the spectra obtained from solution of classic boundary–value problem for the whole CCL shows high accuracy of the method already with 10 sub–layers. The method is applicable at arbitrary cell current. The advantage of this approach is tenfold acceleration of spectra calculations.