An importaint research topic at ZBT is the study of toxic gases and particulate loadings on the cathode of PEM fuel cells. In recent years some significant results have been achieved, especially within the research project "Kathodenluft II".

The lifetime of PEM fuel cells depends on operation conditions (start-stop, load cycles, etc.) and the purity of extern feed gases. Especially cathode gases must be very clean, because the reduction of oxygen at the cathode is a slow process in comparison to the other processes in a fuel cell. Furthermore impurities in the air can contaminate the catalyst, the electrolyte or the GDL. The influence of toxic gases on PEM fuel cells will increase in future years, because the automotive industry must reduce platinum loadings to reach competitive costs. 

The project included extensive laboratory tests with electrochemical measurements methods and long-term tests in outdoor installation. Damage mechanisms and location of attacks could be determined.
 
Furthermore it could be shown that a filter system, used upstream cathode inlet, is able to filter toxic gases and particles from air. This leads to a continuous power characteristic of fuel cells without any voltage drop. Additionally, the application of filter systems, especially by using PEM fuel cells at traffic related areas, results in an increase of lifetime.

• German summary of the results in the latest edition of HZwei (Juli 12)
• The german project report is to be downloaded via IUTA reserach group
• zbt publications

Acknowledgements: This work was supported by the Federal Ministry of Economics and Technology, Germany via AiF, Research project „cathode air II“: IGF project number 16325 N (01.12.2009 – 29.02.2012)