Characterisation of mass transport in mesh-type flow-field based polymer electrolyte membrane water electrolysers by neutron imaging

Flow-fields are essential for effective mass transport in polymer electrolyte membrane water electrolysers (PEMWEs). However, conventional flow-fields often face challenges in achieving reactant homogeneity across the full area of the electrode. This study explores the mass transport characteristics of PEMWEs using a mesh-type flow-field, analysed through neutron imaging and electrochemical impedance spectroscopy. The mesh-type design demonstrates superior cell performance and lower mass transport resistance compared to the conventional parallel design under the conditions tested. Neutron imaging results show that the mesh-type flow-field achieves a more uniform water distribution across the active area, as indicated by significantly lower standard deviations in water thickness. In contrast, the parallel design experiences a more rapid decline in the fraction of water remaining in the flow-field area (indicating a significant build-up of gas bubbles and heterogeneity of available reactant water). This uniformity in water distribution, along with efficient gas transport, facilitates more effective electrochemical reactions, resulting in a ∼5 % reduction in cell potential at a current density of 1000 mA cm−2 compared to the parallel design. These findings highlight the advantages of the mesh-type flow-field in addressing mass transport challenges, positioning it as a promising solution for a wide range of PEMWE applications.