EIS Characterization of the Poisoning Effects of CO and CO2 on a PBI based HT-PEM Fuel Cell

This paper presents test results regarding the poisoning effects of CO and CO2 on H3PO4/Polybenzimidazole (PBI) membrane based high temperature proton exchange membrane fuel cell (HT-PEMFC). Electrochemical impedance spectroscopy (EIS), which is a non intrusive diagnostic tool for electrochemical systems, has been used to investigate these effects.
A single cell test setup consisting of an electrically heated single cell assembly with a PEMEAS CELTEC P membrane electrode assembly (MEA) of an active area of 45cm2 and mass flow controllers for Air, H2, CO and CO2 was constructed in the laboratory. All operational parameters as well as data acquisition are controlled by two LabView programs, running on two separate computers. The impedance spectrum of the fuel cell is recorded at different operating points and then an Equivalent Circuit (EC), proposed for modelling the cell impedance, is fitted to the spectrum in order to analyze and quantify the impact of the individual factors on HT-PEMFC performance.
Results showed that CO poisoning has an effect on all the losses monitored. Intermediate frequency resistances showed higher increase with increasing contamination and decreasing temperature than high frequency resistances, which is attributable to the adsorption of CO on Pt catalyst.