EIS measurements in the diagnosis of the environment within a PEMFC stack

Abstract

The diagnosis of flooding or drying is an important factor in improving the reliability and durability of PEMFCs. Indeed, flooding and drying lead to a reduction in the output voltage delivered by the fuel cell. Among the various diagnostic techniques, electrochemical impedance spectroscopy (EIS) is a powerful tool. In this study, EIS measurements were carried out on a 500 W stack comprised of 16 elementary cells. Electrochemical impedance spectra were recorded either on each cell or on the stack. Use of an electrical equivalent circuit model revealed that flooding mainly affects the transfer resistance and the cathodic Warburg impedance. A diagnostic tool based on these two components is proposed.

Study of anode and cathode starvation effects on the impedance characteristics of proton exchange membrane fuel cells

“…However, the measured impedances presented in Refs. [6,7,12], which were measured in the flooded conditions, do not show a considerable change in the HFR value. Thus, it is not safe to consider HFR as an indicator for anode flooding.…”

“…Flooding is in fact undesirable as it causes partial or local starvation. The reported impedance characteristics obtained under the flooded and normal conditions in PEM fuel cells [e.g., [6][7][8][9][10][11][12][13]] do not normally distinguish the flooding in the anode and cathode electrodes or those are not discussed individually. Therefore, these reported impedances cannot be used to study separately the anode and cathode starvation.…”

PEMFC for aeronautic applications: A review on the durability aspects

“…Ohmic resistance (R Ω ) increases with dehydration which causes local hot spots on the catalyst surface and corrosion of carbon support [95]. Flooding at the cathode reduces the active surface area (ECSA) available for the reaction and limits oxygen diffusion, which in turn increases charge transfer resistance (R ct ) especially at high current densities [33,96]. Furthermore, double layer capacitance (C dl ) is directly proportional to ECSA when the supported catalyst is evenly distributed over MEA surface.…”

Impedance Study on Estimating Electrochemical Mechanisms in a Polymer Electrolyte Fuel Cell During Gradual Water Accumulation

“…The resulting ac load opposition or impedance is commonly represented in a Nyquist plot and can represent the response of the electrochemical mechanisms of the PEFC at different frequencies. Studies presented in literature have been focused on the diagnosis and study of the PEFC during flooding conditions using EIS . An extensive literature review on flooding issues in PEFCs carried out by Li et al.…”