Impact of the gas diffusion layer with wettability distribution on the PEFC performance

Abstract

To make polymer electrolyte fuel cells (PEFCs) competitive, it is necessary to achieve the high current density operation and to improve the flooding performance of the cell. Generally, the water produced in a catalyst layer is accumulated in a gas diffusion layer (GDL). Thus, the water transport from the GDL to the channel is important. In this study, to improve the water transport in the GDL, the novel GDL structure which has the hydrophilic and hydrophobic region in the thickness direction was proposed; this was an attempt to accumulate the water in the hydrophilic region near the separator and to transport the water along the rib from the GDL to the channel. To make the GDL structure with hydrophilic/hydrophobic distribution in the thickness direction, Nafion was coated on the hydrophobic GDL with polytetrafluoroethylene (PTFE). The wettability distribution of the GDL was investigated by the measurement of the contact angle and energy dispersive X-ray spectroscopy (EDS) analysis. Finally, the performance of the cell using the GDL with hydrophilic/hydrophobic distribution was evaluated. The result showed that the cell performance under the high current density is improved by the proposed GDL.