Real‐Time Impedance Analysis for the On‐Road Monitoring of Automotive Fuel Cells

Abstract

The on‐road monitoring of polymer electrolyte membrane fuel cells (PEMFCs) in automotive systems optimizes their efficiency and fuel consumption in addition to increasing their lifetime. In this work, electrochemical impedance spectroscopy (EIS) measurements and special EIS data analysis algorithms were used to quickly identify fuel cell operational modes and failures during cell operation. The approach developed enables the measurement and analysis time of only a few seconds and allows the accurate extraction of information about the membrane and charge transfer resistance. The data analysis procedures show similar accuracy to that of the complex non‐linear least square fitting algorithms. As a result, typical operational failures like air and hydrogen starvation were able to be easily distinguished, and different operational states (membrane humidification, air stoichiometry) of the PEMFCs could be identified.

Analysis of the Capacitive Behavior of Polymer Electrolyte Membrane Fuel Cells during Operation

“…The impedance measurements described above demonstrate that in such a case the differential capacitance increases. It has been shown elsewhere that other error cases, such as dehydration of the polymer and the hydrogen undersupply, lead to a collapse of the cell capacitance [23] . Thus, a drop in voltage in combination with an increase in the capacitance can be attributed to the cathode undersupply.…”

“…It has been shown elsewhere that other error cases, such as dehydration of the polymer and the hydrogen undersupply, lead to a collapse of the cell capacitance. [23] Thus, a drop in voltage in combination with an increase in the capacitance can be attributed to the cathode undersupply. This can be relevant for an impedance-based control strategy for PEMFCs.…”

“…The change of electrical charges at the interface with voltage can arise from the double layer charging and specific adsorption processes [13,19,20] . The cell capacitance during the operation is dependent on many parameters, such as voltage, temperature, hydrogen and oxygen partial pressure as well as membrane humidification, just to mention a few [21–23] …”

“…[13,19,20] The cell capacitance during the operation is dependent on many parameters, such as voltage, temperature, hydrogen and oxygen partial pressure as well as membrane humidification, just to mention a few. [21][22][23] Only several studies have focused on the capacitive behavior of fuel cells under oxygen-saturated and oxygendepleted operational conditions. While some authors observe variations in the capacitance in different operational modes, [21][22][23] the physical origins of these variations remain unclear.…”

“…[21][22][23] Only several studies have focused on the capacitive behavior of fuel cells under oxygen-saturated and oxygendepleted operational conditions. While some authors observe variations in the capacitance in different operational modes, [21][22][23] the physical origins of these variations remain unclear. In oxygen-depleted operation (nitrogen at the cathode), cyclic voltammetry (CV) reveals changes in the cell capacitance due to hydrogen adsorption/desorption and OHlayer formation dependent on the electrode potential.…”