Effect of capillary pressure gradient in microporous layer on proton exchange membrane fuel cell performance

The water discharge capability of the gas diffusion layer (GDL) in a proton exchange membrane fuel cell (PEMFC) is dominantly influenced by the capillary pressure gradient. In this study, three different microporous layer (MPL) manufacturing methods are applied to improve the capillary pressure gradient in the MPL and, consequently, improve the water discharge capability of the GDL. Firstly, the GDL is manufactured by varying the thickness of the MPL. Secondly, hydrophilic carbon black particles are additionally added to the main carbon black particles of the MPL. Finally, different GDLs are fabricated by varying the number of MPL loadings with different viscosities on one side of the substrate. At 100% relative humidity (RH) and a current density of 2.1 A/ cm2, the GDL with a thinner MPL yields 31.9% higher performance than that with a thicker MPL; furthermore, the GDL with the hydrophilic carbon black particles yields 7.2% lower performance than that without the hydrophilic carbon black particles treatment at 100% RH, but the GDL with hydrophilic carbon black particles shows 3.9% higher performance at 30% RH. The GDL loaded with a low-viscosity MPL on top of a high-viscosity MPL demonstrates 81.8% higher performance than that loaded with a low-viscosity MPL alone. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The water discharge capability of the gas diffusion layer (GDL) in a proton exchange membrane fuel cell (PEMFC) is significantly influenced by the capillary pressure gradient. This study explores three different methods of manufacturing the microporous layer (MPL) to enhance the capillary pressure gradient and improve the water discharge capability of the GDL. Varying the thickness of the MPL, adding hydrophilic carbon black particles, and adjusting the number of MPL loadings with different viscosities are all found to have a notable effect on the performance of the GDL.