Improving the gas transport efficiency within gas diffusion layer (GDL) is of vital importance to enhance the overall performance of proton exchange membrane fuel cells (PEMFC) and promoting their commercialization. In this study, the effects of capillary resistance cast by polytetrafluoroethylene (PTFE) and structural modifications including gradient porosity and patterned wettability on liquid water permeation dynamics and electrochemical performance are systematically investigated. Results demonstrate that capillary resistance significantly changes the flow preferences within GDL and the maximum current density and power density. Applying structural modifications can lower the saturation levels within GDL, better separating the paths of liquid water and reactant gas. The capillary pressure-saturation curves (Pc-Sa curves) of modified GDLs show larger inlet capillary pressure and close maximum capillary pressure, indicating that the maximum capillary pressure is mainly dominated by bulk porosity. The maximum current density and power density increases by 6.2% and 4.3% as PTFE content increases from 2% to 10%, and by 3.9% and 2.7%, 4.6% and 4.1% for GDLs with gradient porosity and patterned wettability configurations, proving that increasing surface hydrophobicity and applying structure modification are effective in enhancing the overall cell performance.

GDL,PEMFC,LBM,Water management