On the Importance of MPL Structural Characteristics for PEM Fuel Cell Performance

A systematic study was performed with GDLs based on a singular backing using different MPL types and penetration levels. A simple method to estimate the micro-porous layer penetration in gas diffusion layers based on data obtained from force-deflection behavior of backings and MPL-coated GDLs is proposed. Comparison with SEM and previously published tomographic studies shows that a good estimate for the extent of MPL intrusion into the backing is obtained. MPL loading and penetration is shown to affect different ex-situ GDL properties (in-plane gas permeability, electrical and thermal conductivity) as well as the GDL single cell performance characteristics with respect to humification and high current density operation. Similar effects are reported for MPLs differing with respect to the presence of mud-cracks.