Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: Dielectric and Molecular/Water Interfaces

O 60.8: Vortrag

Mittwoch, 18. März 2015, 16:45–17:00, MA 043

Reduction of the contact resistance of bipolar plates and foils for fuel cells by atmospheric plasma treatment — •Tatiana Fedosenko, Nicolas Wöhrl, and Volker Buck — University of Duisburg-Essen and CENIDE, Carl-Benz-Str. 199, 47057, Duisburg, Germany

Proton-exchange membrane fuel cells typically consist of two electrodes - bipolar plates, separated by an electrolyte in a form of a proton exchange membrane. In one specific implementation these bipolar plates are made from a graphite/polypropylene composite. Polypropylene (PP) is unintentionally enriched at the surface of the bipolar plates during the manufacturing, thereby significantly increasing the contact resistance between individual plates. In this study bipolar plates were treated in air plasma at atmospheric pressure while the etching time and the distance between the surface and plasma was varied. It is shown how the plasma etching removes the excess polymer matrix at the surface. Furthermore it was measured by Raman Spectroscopy that the plasma is etching the smaller nanostructured carbon from the surface, leaving larger graphitic structures. Since fewer interfaces are between the crystals, the scattering of electrons is reduced and hence the conductivity of the etched samples is higher than the conductivity of the untreated samples. The etching effect on the surface is correlated with the plasma properties as measured by optical emission spectroscopy. Atmospheric plasma treatment is demonstrated to be an efficient and scalable method to improve the properties of bipolar plates.