Effect of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layers on PEFC Performance

Abstract

Addressing the voltage loss problem at high current densities is crucial to expand PEFCs output power. One approach to improve water management and extend the cell operating range is modifying the microporous layer (MPL) coated on the gas diffusion layer (GDL). This study developed a novel MPL coated GDL preparation method featuring randomly allocated hydrophobic and hydrophilic pores within the same layer, which was proven by the water permeability test. This design allows excess water at the interface between the catalyst layer (CL) and MPL to be expelled through the hydrophilic pores while maintaining gas transport via the hydrophobic pores to reduce the mass transport resistance. Various hydrophobic and hydrophilic materials were tested, and the different compositions were evaluated to determine the appropriate combination. The results demonstrated that the composite MPL further reduced total oxygen transport resistance compared to the conventional hydrophobic MPL.