Pore Morphology Effects of Liquid/Gas Diffusion Layers in Proton Exchange Membrane Electrolyzer Cells

Hydrogen is now considered the most preferred medium for storing energyout of renewable, intermittent power sources because of its great advantages such as high energy density, low weight, environmental friendliness, etc. Water electrolysis is the most accessible hydrogen production method. Proton exchange membrane (PEM) water electrolysis is attracting much attention with its high efficiency. In a PEM electrolyzer cell (PEMEC), liquid/gas diffusion layers (LGDLs) are porous layers whose main functions are conducting electrons and heat and transporting reactants/products to and from the reaction sites. To achieve high efficiency, a PEMEC demands LGDLs with minimum intrinsic ohmic, thermal, and mass diffusion losses and also low interfacial contact resistances with other components. Thus, the morphologies and surface properties of LGDLs can greatly affect the cell performance. In this research, anode LGDLs featuring pore sizes of approximately ten microns are fabricated by pulsed-laser micromachining (PLM). The effects of pore morphologies, including porosities and pore sizes, are characterized comprehensively ex-situ and in-situ. Electrochemical impedance spectroscopy (EIS) analysis is also carried out to investigate the impact of LGDL pore morphologies on the PEMEC performance. Results from this research can help the community better understand the relationship between LGDL morphology and PEMEC performance. A prediction of the performance at the design stage should also be available based on the morphology of an anode LGDL. Furthermore, an optimal design for anode LGDLs may be acquired.