Detection of water vapor in cathode gas diffusion layer of polymer electrolyte fuel cell using water sensitive paper

Abstract

Water management in cathode electrode of polymer electrolyte fuel cell (PEFC) is essential for high performance operation, because liquid water condensed in porous gas diffusion layer (GDL) and catalyst layer (CL) blocks oxygen transport to active reaction sites. In this study, the water vapor distribution inside the cathode GDL of a PEFC was detected by using water sensitive paper (WSP) to understand the water transport through the cathode electrode during the startup. Furthermore, the liquid water behavior at the cathode was directly visualized using an optical diagnostic, and the water distribution under the current-collecting ribs and gas channels of the cathode separator was investigated. It was found that the water vapor concentration within the cathode electrode begins to increase near the CL in the downstream region immediately after starting the operation. In the cathode upstream region, the water concentration becomes remarkably high under the current-collecting ribs of the cathode separator because the ribs block the water vapor exhaust from the cathode GDL.