Capillary pressure saturation relations for PEM fuel cell gas diffusion layers

Capillary pressure saturation relations (CPSRs) are presented for Toray TGP-H-060 and Mitsubishi rayon carbon fiber paper which can both be used as gas diffusion layers (GDLs) in proton-exchange membrane fuel cells (PEMFCs). The saturation is measured using water over a range of capillary pressures. Boundary and scanning curves for imbibition and drainage are measured to further understand the hysteresis observed during PEMFC operation. The primary source of hysteresis in CPSRs is attributed to the difference in advancing and receding contact angles. The measured hysteresis is predicted to have a significant effect on mass transport in the GDL and thus performance in PEMFCs. (C) 2008 The Electrochemical Society.