Effects of composite porous gas-diffusion layers on performance of proton exchange membrane fuel cell

Abstract

The gas diffusion layer (GDL) is an important component of proton-exchange membrane fuel cells (PEMFCs) that participate in the interplay of the transport of different species. During the assembly of PEMFCs, mechanical pressure is applied to the solid boundary of bipolar plates to reduce the porosity of the adjacent GDL, especially under land areas. This variation in porosity reduces reactant consumption in the catalyst layer and primarily causes non-uniform current density in PEMFCs. To compensate for the loss of porosity in the GDL, a composite porous diffusion layer was used as a GDL with higher porosity in the under-land areas of the GDL than that in the under-channel areas. A numerical simulation was conducted to investigate the effect of the positional variation of porosity on the performance of the PEMFC. The overall performance of the cell was investigated through a polarization plot, and the local mass transport of the reactant species was evaluated at the two reaction sites. The introduction of the proposed composite porous GDL improved the performance of the PEMFC by enhancing the transport of the reactant species to and from the reaction site.