Performance Characteristics and Liquid Water Transport in PEFC with Porous Separator

The porous separator has recently been proposed as an alternative to cells with gas flow channels in PEFCs. In this study, basic characteristics of a PEFC with porous separator were identified using a cell for the direct observation of phenomena at the surface of porous separator and measurements of the local current density. The transport behavior of liquid water inside the porous separator was also investigated using another cell for the direct observation of the porous cross-section. Because of the higher contact resistance, the cell voltage with porous separator is lower than that with serpentine separator, but a stable operation can be maintained with the porous separator under conditions at higher current density. The cross-sectional observation showed that the porous separator is superior in the drainage performance from the surface of gas diffusion layer, and the hydrophilic property of porous separator is important for the better cell performance.