Investigating the Local Membrane Degradation Mechanisms in PEM Fuel Cells

Date created: 
2014-02-27
Identifier: 
etd8251
Keywords: 
PEM Fuel Cells
Local membrane degradation
In-situ experiments
Delamination
Catalyst crack
Local contamination
Abstract: 

As fuel cell industry matures over the years, the reliability and durability issues of this state-of-the-art technology become of greater concern among the researchers of this field. Aiming at durability issues of fuel cells, this research has been dedicated to a novel experimental approach in analysis of local membrane degradation phenomena in PEMFCs, with the aim of shedding light on the potential effects of manufacturing imperfections on this process. Followed by a comprehensive review on historical membrane failure analysis data from Ballard Power Systems’ field operated MEAs, three distinct alternatives have been proposed as potential candidates for initiating or accelerating the local membrane degradation phenomena. Catalyst layer delaminations, catalyst cracks, and local sources of Fenton’s reagents are the three options investigated in the current study. Customized MEAs were designed, fabricated and tested under two different in-situ accelerated-stress-test conditions and extensive post mortem analysis has been done on the end-of-life samples. The observations suggested a significant accelerating effect for iron contamination on membrane degradation process in a global term, leading to remarkably shorter lifetimes, but dismissed the local traces of iron oxide as the local initiators or accelerators of this phenomenon. Studying the potential effects of catalyst-layer delamination revealed that having this defect on the anode side can lead to an extremely thinned membrane, while same anomaly, if placed on cathode catalyst-membrane interface has a negligible effect on the rate of membrane thinning under identical operating conditions. Moreover, a substantial mitigating effect for platinum remainders on the site of delamination has been observed on both tests. Eventually, looking at artificial catalyst layer cracks, it was verified that anode and cathode cracks could have no significant impact on local membrane degradation phenomena. While historically, a great deal of degradation studies has been focused on the cathode side, these findings, when considered as a whole, can change the way industries look at the degradation process. Concluded by these in-situ experiments, anode can actually be considered as a key player in the convoluted degradation process.

Document type: 
Thesis
Rights: 
Copyright remains with the author. The author granted permission for the file to be printed and for the text to be copied and pasted.
File(s): 
Supervisor(s): 
Erik Kjeang
Gary Wang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.
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