Self-supporting microporous layers (MPLs) for PEM fuel cells

The gas diffusion layer (GDL) plays a crucial role for PEM fuel cell performance. The main requirements of a GDL are the provision of gas and water transport as well as significant electrical and thermal conductivity. For the development of PEMFC diffusion media the still unknown influence of the micro porous layer (MPL) on fuel cell performance is a major obstacle. Therefore a self-supporting MPL was developed because it allows basically the measurement of MPL properties separately from the substrate. To get a correlation of the global intrinsic properties of the MPL, like electrical conductivity or hydrophobicity to fuel cell performance, I-V curves up to limiting current densities and electrochemical impedance spectra (EIS) are measured in a 5 cm2 fuel cell setup. Additionally synchrotron X-ray radiography studies were performed to compare the influence of different MPLs on liquid water distribution during fuel cell operation