Abstract
This paper presents the first part of a complete ex-situ characterisation of a wide range of commercial Gas Diffusion Layers (GDLs) used in low temperature and high temperature Proton Exchange Membrane (PEM) fuel cells. Physical and electrical characteristics of the GDLs are reported. The results show that the substrate structure has a significant effect on the mechanical and electrical properties of the GDL. Moreover, the Micro Porous Layer (MPL) structure determines the roughness of the surface, and affects the permeability and porosity of the GDL. It was found that the substrate treatment with PTFE affects the GDL characteristics; PTFE loading increases the GDLs hydrophobicity and permeability, however, decreases its overall porosity and resistivity. Adding a MPL to the substrate, results in a decrease in porosity and permeability and an increase in resistivity. The contact resistance of the GDL and the bipolar plate increases when the GDL thickness and PTFE loading are increased. This technical paper shows a close relationship between GDL materials and their physical characteristics and highlights the importance of optimising GDLs for fuel cell applications.
Highlights
Gas Diffusion Layers (GDLs) are important sub-components in Membrane Electrode Assemblies (MEAs) used in Proton Exchange Membrane Fuel Cells (PEMFCs)
The data of important ex-situ parameters of commercial GDLs used in PEM fuel cells are reported
The results indicate that there is a relationship between the GDL properties, substrate structure, PTFE and Micro Porous Layer (MPL) loading
Summary
Gas Diffusion Layers (GDLs) are important sub-components in Membrane Electrode Assemblies (MEAs) used in Proton Exchange Membrane Fuel Cells (PEMFCs). For GDLs, the carbon substrates are water proofed (e.g. by adding PTFE) to prevent the blockage of pores with water that can disrupt diffusion of reactants to the CLs during fuel cell operation. A Micro Porous Layer (MPL) made of carbon and a hydrophobic agent (e.g. PTFE), is often added on the GDL surface between the CL and the GDL.
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