Investigating the Degradation of Porous Transport Layer (PTL) Materials in Proton Exchange Membrane Water Electrolyzer via in-Operando Distribution of Relaxation Times Approach
Notice bibliographique
Résumé
Proton exchange membrane water electrolyzer (PEMWE) technology, while commercially mature and in high demand, faces degradation issues that lead to performance losses over time. These challenges reduce operational lifetime and increase regeneration and replacement costs. Components of the membrane electrode assembly (MEA), such as the ionomer, catalysts, membrane, porous transport layer (PTL), and bipolar plate (BPP), contribute to its degradation. Among these, PTL degradation is a significant contributor to performance loss. Therefore, understanding the PTL’s degradation mechanism is essential for improving the material's durability and optimizing the electrolyzer’s performance [1]. The PTL degradation not only causes mass transport losses due to inefficient reactant delivery and gas bubble removal but also negatively impacts the catalyst layer/PTL interface and increases contact resistances [2]. Isolating the degradation mechanism of the PTL from other components is challenging, even with advanced techniques like Electrochemical Impedance Spectroscopy (EIS), which often yields data that is complex to interpret. However, the Distribution of Relaxation Times (DRT) analysis presents a promising way of interpreting impedance data to differentiate and track distinct electrochemical phenomena within the complex system of PEM electrolyzers [3]. This work uses the DRT approach on in-operando EIS to interpret electrochemical loss mechanisms inside the cell while comparing the short-term performance of different PTL materials, such as carbon paper with a microporous layer (MPL), and uncoated and platinum-coated Ti felts. We present and compare the initial impedance and polarization results of these PTL materials, and analyze the corresponding DRT spectra at various applied current densities. Additionally, we utilized carbon PTL at the anode to investigate the durability of the PTL. The accelerated degradation profile involved applying a constant current of 1 A/cm² for 6 hours daily, followed by an overnight shutdown as a stressor. Figure 1(a) shows the preliminary DRT results of a PEMWE cell with carbon paper PTL, indicating an increase in diffusion impedance from 0.51 mΩ to 4.6 mΩ as the current density increases from 0.5 to 2 A/cm². This impedance increase can be attributed to the evolution of more oxygen bubbles at higher currents, which hinder water transport due to carbon paper's small pores size and low wettability [4]. At a current density of 1 A/cm2, the diffusion impedance on the carbon paper PTL was shown to be 9.2 times higher than Ti-felt PTL, as revealed by DRT analysis. This significant difference is likely due to the hydrophobic nature of the carbon PTL, which results in poor mass transport due to inadequate water interaction. Furthermore, the onset cell degradation test with the carbon paper PTL resulted in voltage overshoot after 160 hours, with the DRT analysis indicating increased diffusion and charge transfer resistances. Similarly, DRT analysis of Ti felt degradation showed increased ionic transport resistance and contact resistance over time, leading to passivation after short-term operation. In general, the online DRT analysis revealed that the interfacial properties of PTL materials strongly depend on the type of material used. Also, DRT analysis assists in identifying the root cause of degradation. References: [1] C. C. Weber, J. A. Wrubel, L. Gubler, G. Bender, S. De Angelis and F. N. Büchi, ACS Applied Materials & Interfaces, 15, 34750 (2023). [2] S. Duran, A. Grimaud, M. Faustini and J. Peron, Chemistry of Materials, 35, 8590 (2023). [3] J. K. Lee, F. Babbe, G. Wang, A. W. Tricker, R. Mukundan, A. Z. Weber and X. Peng, Joule, 8, 2357 (2024) [4] K. Bromberger, J. Ghinaiya, T. Lickert, A. Fallisch and T. Smolinka, International Journal of Hydrogen Energy, 43, 2556 (2018) Figure 1
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Comment cette classification a été obtenuedéplier
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 | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| 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 ».