On the Compressibility of Gas Diffusion Layers in Proton Exchange Membrane Fuel Cells

The mechanical behavior under compression for a number of gas diffusion layers (GDLs) and a sealing gasket used in proton exchange membrane fuel cells (PEMFCs) has been investigated. The results show that the stiffness of the carbon substrate increases with increasing polytetrafluoroethylene (PTFE) loading. Also, coating the carbon substrate with the microporous layer (MPL) significantly enhances the stiffness of the GDL. On the other hand, the stiffness of the GDL appears to slightly decrease with an increase in the PTFE loading present in the MPL. For a given practical compressive pressure, the mechanical behavior of the GDLs is hugely controlled by the less compressible sealing gaskets. Furthermore, it has been found that the compression curves for the tested materials must be corrected for machine compliance. Otherwise, the stiffness of the tested materials is significantly underestimated.