Hervé Galiano

3D Modeling of Four-Points Probe Method: Application to Characterisation of Fuel Cell’s Bipolar Plates

For reducing fuel cell stack cost new materials for bipolar plates (BPs) are under development. Quality of this new BPs has to be checked. The four-points probe method is commonly used for measuring of electrical conductivity; however sample’s geometry has a strong impact on the accuracy of this method. For this reason, it is not possible to use the classical assumptions for the interpretation of the electrical conductivity measurements with respect to the case of BPs. In this paper, a finite elements numerical model is developed for the calculation of the influence of the sample’s geometry on the accuracy of four-points probe method. The approach presented here allows obtaining the corrective factor for the four-points method taking into account the real geometry of BPs and evaluating the border effects related with the position of the probe. The obtained results can be used for diagnostic of the quality of BPs.© 2009 ASME

Proton Exchange Membrane Development and Processing for Fuel Cell Application

The development of new proton exchange membranes for PEMFC has to be related to the membrane processing as it can change drastically the final properties of the material. Indeed, for the same material, a membrane prepared by a solvent-casting process has a lower lifetime than an extruded one. The proton conduction of the membrane can also be dependent on the membrane processing, especially when some removable plasticizers are used to perform the membrane extrusion. Some residual porosity, left in the material after removing the plasticizer, is suspected to enhance the proton conduction of the film. Fuel cell experiments have shown that extruded sulfonated polysulfone membrane can give the same performance as a Nafion® reference membrane whereas the proton conductivity of PSUs is twenty times lower than the Nafion® one. Additional improvements of the membrane properties can also be expected by adding some proton conductive fillers to the organic polymer. This approach enhances the proton conductivity of sulfonated polysulfone to values similar to Nafion®. On the other hand, when Nafion® is used as a matrix for the proton conductive fillers, a very significant improvement of fuel cell performance is obtained.