Electrochemical Pressure Impedance Spectroscopy for PEM Fuel Cells: Are the Measured Spectra Unique?

Abstract

Pressure perturbation δ p applied at the PEM fuel cell cathode channel leads to oscillating cell potential and current. Experimental spectra δ V/δ p reported so far have been obtained by measuring cell voltage response δ V under fixed total current in the external load. A 1d+1d model for electrochemical pressure impedance of a PEMFC with the straight cathode channel shows that fixing a total current leads to a poorly defined problem which allows for multiple solutions depending on random fluctuations of local current. From experimental perspective it means that the measured spectra are, in general, not reproducible.