(358a) Pathways Toward Efficient and Durable AEM Water Electrolyzers Enabled By Electro-Active Ptls

Hydrogen will play a crucial role in decarbonization efforts, especially for heavy industries.^[1] Durable, efficient, and low-cost electrolyzers are the core technology necessary to realize economical and green hydrogen production. Anion exchange membrane water electrolyzers (AEMWE) are an emerging technology that combines the benefits of low components cost of conventional alkaline electrolyzers and the high efficiency of proton-exchange membrane (PEM) electrolyzers.^[2] A significant hurdle to the deployment of AEMWEs is durability under industrially relevant conditions. Here, we comprehensively demonstrate how porous transport layers comprised of natively active materials (PTL electrodes) can be used to achieve efficient and durable AEMWEs.^[3] Specifically, stainless-steel fiber PTLs were used as anodes, without the addition of a catalyst layer. When comparing the PTL electrode to traditional catalyst layers, electrolyzer cells with several commercial anion-exchange ionomers (AEI) were subjected to current cycling. This accelerated stress testing (AST) of the electrolyzer cells showed that no significant degradation in the PTL electrode, while cell using traditional catalyst layers exhibited a loss in performance and the complete degradation of the ionomer functional group. When assessing the industrial applicability, the active area of the electrolyzer was increased 50 cm², which showed the same performance as the 5 cm² cell. The durability of the electrolyzer was tested at 2 A cm^-2 in 0.1 M KOH for 660 h. During this period, the cell exhibited a degradation rate of 5 µV h^‑1, which is comparable to typical PEM electrolyzers. The use of experiment and modeling was used to investigate the role of the structure of the PTL in influencing cell performance. The inclusion of a denser layer on the membrane side increased the activity of the electrode by decreasing the bubble coverage on the fiber surfaces and increasing the effective electrolyte conductivity within the electrode. Finally, we demonstrate a facile etching method to modify the surface of the PTL fibers to increase the active surface area of the anode and achieve a cell current density of 2.3 A cm^-2 at 1.8 V.

References:

[1] D. S. Mallapragada, Y. Dvorkin, M. A. Modestino, D. V Esposito, W. A. Smith, B.-M. Hodge, M. P. Harold, V. M. Donnelly, A. Nuz, C. Bloomquist, Joule 2023, 7, 23–41.

[2] L. Wan, Z. Xu, Q. Xu, M. Pang, D. Lin, J. Liu, B. Wang, Energy Environ Sci 2023, 16, 1384–1430.

[3] A. W. Tricker, T. Y. Ertugrul, J. K. Lee, J. R. Shin, W. Choi, D. I. Kushner, G. Wang, J. Lang, I. V Zenyuk, A. Z. Weber, X. Peng, Adv Energy Mater 2024, 14, 2303629.