Understanding GDL properties and performance in polymer electrolyte fuel cells

El-Kharouf, Ahmad (2014). Understanding GDL properties and performance in polymer electrolyte fuel cells. University of Birmingham. Ph.D.

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Abstract

The Gas Diffusion Layer (GDL) has the important role of transporting the reactants into, and products out of the cell. This study aims to provide insights for understanding the relationship between GDL properties and the performance of PEFCs.

Ex-situ characterisation techniques were employed to study the mechanical, physical and electrical properties of the GDL. The relationship between the various properties of GDL was investigated and discussed in this work. The study shows that characteristics such as GDL thickness, bulk density, PTFE and MPL content, porosity, hydrophobicity, permeability and electrical conductivity are closely connected.

The effect of compression on the cathode GDL performance in PEFC membrane electrode assembly (MEA) is discussed using Polarisation (IV) curve and electrochemical Impedance Spectroscopy (EIS). Compression affects the electrical and mass transport properties of the GDL and therefore needs to be optimised. The results show that there is an optimum compression point, at which; a minimum contact resistance and optimum water transport are achieved. The optimum compression level is dependent on the GDL properties. The optimum compression ratio varies for the different GDLs according to the difference in the material properties. At optimum compression, the performance of the different GDL materials was compared to understand the effect of the GDL properties on the performance. GDL characteristics such as structure, thickness, bulk density, PTFE loading, and MPL presence have a direct effect on the MEA performance and need to be optimized for the different PEFC applications.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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