3D structured liquid/gas diffusion layers with flow enhanced microchannels for proton exchange membrane electrolyzers

Porous transport layers (PTLs) work as key water/gas transport components in proton exchange membrane electrolyzer cells. In PTLs, the gas accumulation under the lands of bipolar plate (BP) has been widely recognized, which decreases the local water saturation and blocks some active areas. Especially for some 2D structured PTLs, the absence of in-plane transport ability raises transport concerns at high current densities. In this study, a wet etching method is introduced to fabricate 3D-structured PTLs, named flow enhanced liquid/gas diffusion layer (FELGDL) for promoting multiphase transport under BP lands. In-situ performance evaluation validates a 330-mV voltage drop and a 7.9% efficiency improvement at 6 A/cm2 compared with the 2D-structured LGDL, which are mainly attributed to the improved reactant supply to the pores under BP lands. Additionally, the mass transport limitation is extended from 6.3 to 9.0 A/cm2 with an anode water flow rate of 20 mL/min. By the in-situ visualization method, the enhanced in-plane mass transport under BP lands is directly visualized. The successful fabrication and performance validation of FELGDL opened a new direction to high-performance 3D structured PTL manufacturing.