Effects of Reinforcement Type on the Structure and Properties of Perfluorosulphonic Acid Membranes for Polymer Electrolyte Membrane Fuel Cells
Bibliographic record
Abstract
Fuel cell membrane durability remains one of the key challenges limiting the wide scale adoption of fuel cell technology. Membrane degradation in polymer electrolyte membrane (PEM) fuel cells limits the operational lifetime of the fuel cell and prevents the industrial targets from being met. A common approach to increasing the lifetime of membranes includes the addition of a reinforcement layer to increase the mechanical durability of the membrane while not adversely affecting the performance [1,2]. Although reinforced membranes are widely used in industry, there is a literature gap considering membrane structure and properties in relation to durability. This work contributes to characterizing the effects of reinforcement type on the membrane properties. In this study a selection of perfluorosulphonic acid (PFSA) ionomer membranes with expanded polytetrafluoroethylene (ePTFE) reinforcements were tested, these include two novel DMR100 membranes with different reinforcements and Nafion XL compared to a conventional, non-reinforced Nafion NRE-211 for reference. All of these membranes contain common PFSA ionomer and differ primarily in the type of reinforcement layer and membrane thickness. The study addresses comparison between the membrane chemical composition, water uptake, crystallinity, and mechanical strength. Methods of ex situ characterization include solid state nuclear magnetic resonance (SS_NMR), small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR), and dynamic mechanical analysis (DMA). Membrane chemical structure and properties are measured by SS-NMR and FTIR, whereas the water uptake, domain spacing, and crystallinity are assessed by SAXS/WAXS study of hydrated and dry membranes [3-5]. Tensile mechanical properties are measured under room temperature (23°C, 50% RH) and fuel cell conditions (80°C, 90% RH) by DMA [6]. Overall, this paper contributes both qualitative and quantitative understanding of the key structural properties of membranes with different reinforcement resulting in novel knowledge about membranes that can be leveraged for improved fuel cell durability. References: [1] Y. Xing, H. Li, G. Avgouropoulos, “Research Progress of Proton Exchange Membrane Failure and Mitigation Strategies,” Materials, vol. 14, no. 2591, pp. 1-17, May 2021, doi:10.3390/ma14102591. [2] Y. Tang, A. Kusoglu, A.M. Karlsson, “Mechanical Properties of a Reinforced Composite Polymer Electrolyte Membrane and its Simulated Performance in PEM Fuel Cells,” Journal of Power Sources, vol. 175, no. 2, pp. 817-825, Oct 2008, doi: 10.1016/j.jpowsour.2007.09.093. [3] M. Robert, A. El Kaddouri, J. Perrin, S. Leclerc, O. Lottin, “Towards a NMR-Based Method for Characterizing the Degradation of Nafion XL Membranes for PEMFC,” Journal of the Electrochemical Society, vol. 165, no. 6, pp. F3209-F3216, March 2018, doi:10.1149/2.0231806jes. [4] M. Fujimura, T. Hashimoto, H. Kawai, “Small-Angle X-ray Scattering Study of Perfluorinated Ionomer Membranes: Origin of Two Scattering Maxima,” Macromolecules, vol. 14, pp. 1309-1315, April 1981. [5] J. Li, M. Pan, H. Tang, “Understanding short-side-chain perfluorinated sulfonic acid and its application for high temperature polymer electrolyte membrane fuel cells,” RSC Advances, vol. 4, pp. 3944-3965, 2014, doi: 10.1039/c3ra43735c. [6] S. Bhattacharya, J. Leung, M.V. Lauritzen, E. Kjeang, “Isolated chemical degradation induced decay of mechanical membrane properties in fuel cells,” Electrochimica Acta, vol. 352, no. 136489, pp. 1-16. May 2020, doi: 10.1016/j.electacta.2020.136489. Acknowledgements: This project has been undertaken thanks to funding from Dongyue Group, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Western Economic Diversification Canada, and the Canadian Research Chairs Program.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".