Promoting AEM Water Electrolyzer Performance and Reproducibility by Tumbler Milling of Ni3fe-LDH OER Catalyst

Abstract

Anion exchange membrane water electrolysis is an attractive clean energy technology for producing hydrogen for energy storage, transport 1,2 and numerous other applications. Rational choice of highly active and stable catalysts as well as the proper design of catalyst layers are crucial to achieve technical relevance of electrolyser systems. The establishment of clear understanding of optimal catalyst treatment and methods of implementation are key steps towards optimized electrolyzer performance and durability. One aspect of catalyst performance in catalyst layers is the catalyst size distribution. A multimodal size distribution of catalyst particles or agglomerates can jeopardize the layer homogeneity and thus electrode performance.In this work, the effect of high-energy ball tumbling milling on the promising Ni3Fe-LDH OER catalyst followed by catalyst dispersion control was correlated to the microstructure of the catalyst layer, the achieved catalyst activity and utilization, and the resulting single cell performance and stability. Physico-chemical characterization confirmed the stable layered double hydroxide structure of the catalyst. By milling, a 300-fold reduction of catalyst agglomerate size, and an 8.8-fold increase of the geometrical surface was achieved. The optimized solvent compositions effectively increased the catalyst ink stability. We found that a significantly decreased catalyst agglomerate size resulted in very homogeneous mixtures of catalyst and ionomer. By tailoring the electrode structure design, lower internal electronic resistances of the electrodes, decreased charge-transfer resistances (Rct) of the membrane electrode assembly, and stable single cell durability of 1000 h with a minor degradation rate of 57 µV h-1 were accomplished.This work presents a facile and scalable approach of NiFe-LDH catalyst treatment and dispersion control and provides a guideline to follow for further electrode development and increased AEM water electrolyzer performances. References (1) Hydrogen Applications. Hydrogen Europe. 2020. https://hydrogeneurope.eu/hydrogen-applications (accessed Jan 7, 2022).(2) Vincent, I.; Bessarabov, D. Low Cost Hydrogen Production by Anion Exchange Membrane Electrolysis: A Review. Renew. Sustain. Energy Rev. 2018, 81 (August 2016), 1690–1704. https://doi.org/10.1016/j.rser.2017.05.258. This work has been performed in the frame of the CHANNEL project. This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under grant agreement No 875088. This Joint undertaking receives support from the European Union's Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.