Manufacturable Microporous Layers on Sintered Titanium for PEM Electrolysis Applications

Abstract

Renewed interest in green hydrogen has prompted a re-examination of the components of proton-exchange membrane water electrolyzers to improve stack durability and lower net hydrogen cost. A key component identified as a driver of cell performance and durability is the anode porous transport layer (PTL). The PTL dictates electrical resistance between anode and flow field, manages two-phase flow at the anode interface, and sinks heat from the electrolysis reaction.Efforts to optimize the PTL have typically focused on limiting titanium passivation and optimizing delivery of water and discharge of oxygen at the anode. However, recent work has shown another important effect related to the contact area of the PTL with the anode catalyst layer. Multiple investigators have shown that highly flat and smooth PTLs enhance cell durability, particularly in the case of low anode catalyst loadings (< 0.5 mgIr/cm2). In those studies1–5, commercial PTLs were modified to obtain more uniform surfaces. In some cases this is effected by attachment of finely structured microporous layers (MPLs) that improve catalyst utilization and eliminate localized heating.An integrated manufacturing approach is required to enable commercial adoption of advanced PTLs featuring microporous layers. In this contribution, we investigate multiple routes and materials systems for obtaining manufacturable MPLs. We assess the relative merits of each method with respect to feasibility and resultant component characteristics, and validate ex situ characterization with single-cell electrolyzer durability testing using catalyst-coated membranes with low Ir loadings. References (1) Lettenmeier, P.; Kolb, S.; Sata, N.; Fallisch, A.; Zielke, L.; Thiele, S.; Gago, A. S.; Friedrich, K. A. C Energy Environ. Sci. 2017, 10 (12), 2521–2533. https://doi.org/10.1039/C7EE01240C.(2) Kang, Z.; Yang, G.; Mo, J.; Yu, S.; Cullen, D. A.; Retterer, S. T.; Toops, T. J.; Brady, M. P.; Bender, G.; Pivovar, B. S.; Green, J. B.; Zhang, F.-Y. Int. J. Hydrog. Energy 2018, 43 (31), 14618–14628. https://doi.org/10.1016/j.ijhydene.2018.05.139.(3) Lee, J. K.; Lee, C.; Fahy, K. F.; Kim, P. J.; LaManna, J. M.; Baltic, E.; Jacobson, D. L.; Hussey, D. S.; Stiber, S.; Gago, A. S.; Friedrich, K. A.; Bazylak, Energy Convers. Manag. 2020, 226, 113545. https://doi.org/10.1016/j.enconman.2020.113545.(4) Schuler, T.; Ciccone, J. M.; Krentscher, B.; Marone, F.; Peter, C.; Schmidt, T. J.; Büchi, F. N. Adv. Energy Mater. 2020, 10 (2), 1903216. https://doi.org/10.1002/aenm.201903216.(5) Lee, J. K.; Schuler, T.; Bender, G.; Sabharwal, M.; Peng, X.; Weber, A. Z.; Danilovic, N. Appl. Energy 2023, 336, 120853. https://doi.org/10.1016/j.apenergy.2023.120853. Figure 1