Liquid Water Permeability in a Hydrophobic Microporous Layer for the Anode Interdigitated Flow Field of a Gas-Liquid Separating Polymer Electrolyte Membrane Water Electrolyzer

Abstract

A novel interdigitated flow field for polymer electrolyte membrane water electrolyzers composed of oxygen exhaust channels apart from liquid water feed channels has been developed for ground and space applications. This design can internally separate oxygen gas and liquid water between the flow channels, dispensing with water circulators for bubble removal and external separators with natural or centrifugal buoyancy. In this electrolyzer, pressurized liquid water is injected in the in-plane direction from the water channels to the catalyst layer through the hydrophobic microporous layer (MPL) of the anode porous transport layer. The produced oxygen gas is discharged in the through-plane direction of the MPL, taking advantage of the capillary pressure in the MPL. This study conducted liquid water permeability tests on the MPL with pressurized water. We find gradual permeability decreases with time for different liquid water pressures. The permeability will be a useful parameter for the optimal structural designs of this electrolyzer.