Impact of the Microporous Layer on Gas Diffusion Layers with Patterned Wettability II: Operando Performance and Water Distribution Analysis by Neutron Imaging

Abstract

We present the operando performance of modified gas diffusion media (GDM) in polymer electrolyte fuel cells (PEFCs) complemented by neutron imaging and pulsed gas analysis, following our previous publication on synthesis and water distribution of modified GDMs. We tested different types of hydrophobic GDMs: a commercial GDM, a GDM with highly porous microporous layer (MPL) and other with crack-free MPL and contrasted them to modified GDM. The modified materials consists on gas diffusion layers (GDL) with patterns of hydrophilic and hydrophobic regions and with different crack-free MPLs. To enhance the GDL patterned wettability efficiency "weak spots" such as a patterned wettability MPL or micro-holes punched into the MPL aligned with the pattern of the GDL were incorporated into the samples and their performance was contrasted to a GDL with patterned wettability and hydrophobic MPL. The experiments show that the GDMs with crack-free MPLs (with or without patterned wettability GDLs) have a higher cell performance and lower mass transport losses than the other fully hydrophobic GDM. No significant performance difference could be established due to the incorporation of modifications to the GDM.