Interactions between Gas Diffusion Layer Structure and Membrane Durability in Fuel Cells
Notice bibliographique
Résumé
Quality control of membrane electrode assembly (MEA) components is critical for the durability and lifetime of fuel cells. Previous gas diffusion layer (GDL) research has shown that features such as microporous layer (MPL) cracks or substrate pores may contribute to buckling-driven cracks in the membrane 1,2 . Our group recently reported a methodology for controlled implementation of GDL holes to isolate and determine their express impact on membrane durability 3 , which revealed that through-plane catalyst-coated membrane (CCM) cracks are likely to develop at small GDL holes located in regions under high compression, due to maximum stress concentration. The objective of the present work is to evaluate the systematic interactions between the GDL structure and chemo-mechanical membrane durability in fuel cells, considering a broader range of GDL materials with variations in physical properties and surface structure and their compatibility with thin, mechanically reinforced membranes. An in-situ 4D visualization technique by X-ray computed tomography (XCT) was chosen for the study, and the GDL samples were visualized using an XCT-compliant small-scale fuel cell, as was previously shown 4 . The MEAs comprised of GORE-SELECT® mechanically reinforced membrane, Pt/C catalyst layers, and GDLs with selected variations in substrate architecture (hydroentangled, dry-laid (Freudenberg) and wet-laid (AvCarb®) non-woven carbon papers), MPL thickness, and artificial hole presence. Based on previous work 3 , a 0.2 mm 2 artificial through-thickness GDL hole was implemented within the fuel cell active area and the XCT field of view on the cathode GDL. All MEAs, with and without GDL holes, were tested under a custom-developed chemo-mechanical accelerated stress test protocol with an inclination towards mechanical stressors. Periodic identical location in-situ imaging was performed to track the degradation phenomena. The XCT images indicated significant uniform membrane thinning and minor GDL impingement in the defect-free baseline wet-laid GDL MEA. However, when tested with GDL holes, severe membrane buckling resulted in a substantial crack network formation in the CCM beneath the channels. The outcomes for the dry-laid and wet-laid substrates were similar in terms of test lifetimes, although certain differences were observed in the localized failure mechanisms. The extent of non-uniform global membrane thinning and fiber impingement increased drastically for the case of thin MPL. It is worth noting that exacerbated membrane thinning may be attributed to the membrane not being chemically stabilized. Furthermore, the relatively high surface roughness of the thin MPL enhanced the crack network formation in the catalyst layer, significantly reducing the membrane lifetime. Therefore, this study demonstrates that MPL roughness diminishes the lifespan of the MEA by promoting the creation of impingement sites and buckling, which leads to catalyst layer cracks and membrane thinning, culminating in membrane failure. A smooth MPL structure that is capable of distributing applied stress is required in order to ensure high membrane durability. Keywords: fuel cell, membrane durability, X-ray computed tomography, gas diffusion layer defect, quality control Acknowledgement This research was supported by the Natural Sciences and Engineering Research Council of Canada, Mitacs, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Pacific Economic Diversification Canada, and Ballard Power Systems. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program. References: S. Prass, S. Hasanpour, P. K. Sow, A. B. Phillion, and W. Mérida, J. Power Sources , 319 , 82–89 (2016). D. Ramani et al., J. Power Sources , 512 , 230446 (2021). Y. Chen et al., ECS Meet. Abstr. , MA2023 - 02 , 1780–1780 (2023). Y. Chen et al., J. Power Sources , 520 , 230674 (2022).
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Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».