Porous media flow field for polymer electrolyte membrane fuel cell: Depression of gas diffusion layer intrusion, deformation, and delamination

Abstract

Porous media flow fields have received a growing attention for polymer electrolyte membrane (PEM) fuel cell application due to their multiple benefits, including enhancements in thermal removal, electron conduction, and two-phase flow control. This study numerically investigates the intrusion of the gas diffusion layer (GDL) into the gas flow channel (GFC) and potential delamination at the GDL and microporous layer (MPL) interface upon land compression and evaluates their depressions by adoption of the porous media flow field. Finite element simulation is conducted to predict the GDL deformation and stresses for both porous media and traditional hollow GFCs. The model predictions are compared with other literature data of GDL intrusion/deformation for traditional hollow GFCs. The results show that GDL intrusion may significantly reduce the GFC space and GDL deformation causes a large spatial variation of porosity and permeability of traditional GFCs. Adoption of the porous media GFCs significantly depresses the GDL intrusion and deformation and hence the porosity/permeability spatial variation. In addition, the shear and tensile stresses at the GDL-MPL interface are evaluated, which are major causes for delamination. It is found that both compressive and tensile stresses may be induced by assembly pressure for traditional GFCs. The shear stress can be significantly depressed and tensile stress can be avoided by porous media GFCs, thereby mitigating the risk of GDL/MPL delamination.