Characterization of Microporous Layer in Carbon Paper GDL for PEM Fuel Cell

Characterization of a custom series of Toray TGP-H-060 carbon paper gas diffusion layer (GDL) was performed by using scanning electron microscopy (SEM) images, pore size distribution (PSD), MacMullin number, and fuel cell performance. The GDLs were customized by the addition of a microporous layer (MPL) and the treatment of, either or both, the substrate and MPL with 10% and 40% hydrophobic agent. SEM images correlated very well with the data shown for PSD. Distinction between the substrate layer and the MPL were clearly shown as two different slopes in the integral distribution and two different peaks in the differential distribution. The Mac Mullin number increased with increase in wet proofing but decreased with the addition of the MPL. Results showed that the cell performance with the different GDLs is affected by a competitive effect of pore volume in the substrate region, wet proofing treatment, and the Mac Mullin number.