Evaluation of Perforated Porous Transport Layers for Proton Exchange Membrane Water Electrolyzers

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Decarbonizing hard-to-electrify sectors, such as ammonia and cement production, requires the use of a clean energy carrier. Hydrogen is the most promising option and can be renewably produced using proton exchange membrane water electrolyzers (PEMWEs). 1 Deployment of PEMWEs is currently limited by stack costs. Nearly 10% of current stack costs can be attributed to the porous transport layer (PTL). 2 The highly acidic environment at the anode of the PEMWE necessitates the use of titanium. PTLs must also facilitate liquid and oxygen transport, remove heat, be sufficiently electrically conductive, and provide mechanical support to the membrane. The cost of PTLs can be lowered by reducing the thickness to minimize titanium usage. Conventional sintered Ti powder and Ti felt PTLs are between 250 - 500 µm thick. 3 Perforated PTLs fabricated by lithography or laser-drilling offer thicknesses as low as 25 µm. 4 The nature of perforated PTLs allows for fine-tuning the morphology to optimize electrochemical cell performance. In this work we evaluate the fluid transport, electrochemical performance, and mechanical stability of a tri-layer perforated PTL. The layers have thicknesses of 12.5 µm, 25 µm, and 50 µm respectively and pore diameters of 10 µm, 20 µm, and 40 µm. The porosity of each layer is 40%. The pore diameters, pore shape, and porosities are then varied for each layer to understand their impact on through-plane (TP) permeability, cell voltage at 3 A cm -2 , and mechanical deformation. A 3D single-phase computational fluid dynamics (CFD) model is used to numerically measure the TP permeability, and a 2D multiphysics electrochemical model is used to investigate the electrochemical performance. The PTL geometries with sufficient permeability (>10 -13 m 2 ) and low cell voltage at 3 A cm -2 are then evaluated for mechanical stability under differential pressure using finite element analysis (FEA). The results from this study will help to optimize the design of perforated PTLs. References: C. R. Wang et al., Chem Rev (2025) https://pubs.acs.org/doi/10.1021/acs.chemrev.3c00904. A. Badgett et al., Updated Manufactured Cost Analysis for Proton Exchange Membrane Water Electrolyzers , Golden, CO, (2024) https://www.nrel.gov/docs/fy24osti/87625.pdf. J. Parra-Restrepo et al., Int J Hydrogen Energy , 45, 8094–8106 (2020). X.-Z. Yuan et al., Sustain Energy Fuels , 6, 1824–1853 (2022).

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