Interactions between Gas Diffusion Layer Structure and Membrane Durability in Fuel Cells
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".