Effects of impurities in the cathode airflow on proton exchange membrane fuel cell stacks

Fuel cells for mobile applications obtain their oxygen from the ambient air in road traffic. This air has contaminations of various impurities that can have negative effects on the lifetime of fuel cell systems in vehicles. The identified most relevant contaminants are toluene, nitrogen dioxide, ammonia, and sulfur dioxide. A modified test bench enables different dosages of the above-mentioned pollutant gas concentrations on the cathode side. We examined influences both in static cycles for quasi-steady states and in dynamic cycles for rapid load changes to examine reversible and irreversible degradation effects. We showed that the harmful cathode gases examined could lead to a shortening of the service life of fuel cells. Whereas this is well known for higher concentrations of pollutants, this contribution provides data in the sub-ppm range – including the effects of gas mixtures – for which literature data is still limited.

Additionally, a physical fuel cell model is developed to analyze the effects of various contaminants. The overall intention is to determine acceptable contamination levels and thereby increase the lifetime of fuel cells with the help of simulations. The presented model allows for the computation of cell voltage dependent on cathode side media conditions.