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O: Fachverband Oberflächenphysik

O 30: Surface Chemical Reactions and Heterogeneous Catalysis II

O 30.3: Vortrag

Dienstag, 1. April 2014, 11:00–11:15, PHY C 213

Improvement of the electrical conductivity of bipolar plates for fuel cells by plasma etching in carbon dioxide environment — •Tatiana Fedosenko, Nicolas Wöhrl, and Volker Buck — Faculty of Physics, University of Duisburg-Essen, Carl-Benz-Str. 199, 47057 Duisburg, Germany

Bipolar plates for the fuel cells, made of carbon-polymer composites, are one way to distribute the fluid and to conduct the current from the anode of one cell to the cathode of the adjacent cell. However, polypropylene (PP) significantly decreases the contact conductivity between the plates in a stack. It is possible to improve the contact conductivity by etching the PP at the surface in microwave plasma. A microwave plasma source is used in remote mode (CYRANNUS by iplas) that allows plasma treatments up to atmospheric pressure, making the process scalable for industrial applications.

In this study the bipolar plates are etched in carbon dioxide plasma, varying the etching time. SEM and Fourier transform infrared spectroscopy (FTIR) is used to analyze the changes in the surface chemistry. Plasma etching is more advanced than the deposition of the coating of electrocatalytic materials onto the surface of the bipolar plates, since such coating must meet many criteria: a very good adhesion, the coating should not be degraded by high temperatures and water.

Contact resistivity measurements are interpreted with respect to the etching of the surface and rearrangements of the chemical bonds in the PP due to plasma irradiation of the surface.