Heterogeneous through-plane distributions of polytetrafluoroethylene in polymer electrolyte membrane fuel cell gas diffusion layers

Polytetrafluoroethylene (PTFE) has been widely employed as a hydrophobic coating for the polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layer (GDL). Despite a number of application techniques available, a method of quantifying the distribution of PTFE in the through-plane direction of the GDL has not been well established. In this work, we present a novel method for measuring heterogeneous through-plane PTFE distributions within the bulk of the GDL using scanning electron microscopy (SEM) energy dispersive X-ray spectrometry (EDS) imaging. To the authors' best knowledge, this work represents the first direct experimental investigation of the through-plane distributions of PTFE for various commercially available GDLs. SEM EDS imaging of typical PTFE distributions for paper, felt, and cloth GDLs are presented and discussed. SEM backscatter electron images (SEI) are also provided to enable the comparison of PTFE distributions with the morphological features of the GDL This work has the potential to be employed to tune PTFE distributions for optimal water management in the GDL for improving the overall design and performance of PEMFCs. (C) 2011 Elsevier B.V. All rights reserved.