Investigation of Degradation Mechanism of Liquid Alkaline Water Electrolyzer Under Dynamic Operation Condition

Abstract: Liquid alkaline water electrolyzers (LAWEs) occupy a pivotal position in the realm of large-scale green hydrogen production 1 . However, LAWEs face a notable challenge in terms of pronounced electrode degradation under dynamic operating conditions, particularly the induced reverse current phenomenon experienced during transit start-up/shut-down operation 2 . In this study, in order to comprehend the degradation mechanism of LAWE under dynamic operational conditions, a three-electrode LAWE membrane electrode assembly (MEA) setup is designed to decouple the anode and cathode polarization behavior and track the anode/cathode performance during reverse current operation. Combined with post-mortem characterization, it is demonstrated that the anode performance is improved during reverse current operation due to the continuous formation of OER-active species NiOOH/Ni(OH) 2 . While severe cathode degradation is found, resulting from the irreversible oxidation of Ni metal to Ni(OH) 2 , which leads to worsened activity towards HER, decreased conductivity and significant strain-induced mechanical degradation. This research offers a comprehensive examination of the electrode degradation mechanism in LAWE, providing valuable insights to enhance its adaptability to dynamic operations, and contribute to the widespread application of green hydrogen production through electrolysis. Acknowledgement The authors acknowledge the Department of Energy-Office of Energy Efficiency and Renewable Energy-Hydrogen and Fuel Cell Technologies Office (DOE-EERE-HFTO) and the H 2 from Next-generation Electrolyzers of Water (H2NEW) consortium for funding under Contact Number DE-AC02-05CH11231. References: Ayers, N. Danilovic, R. Ouimet, M. Carmo, B. Pivovar and M. Bornstein, Annu. Rev. Chem. Biomol. Eng. 2019, 10, 219-239. Kim, S. Jung, K. Kim, H. Kim, J. Kwon, J. Lee, H. Cho, Y. Kim, JACS Au , 2022, 2, 2491-2500.