Characteristics of porous separators

Anode flow plate for current density measurement 

Direct view of liquid water transport in a cross-section of the hydrophilic porous material, with times after start of droplets emerging fi-om the GDL. 

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Decisive characteristics of porous separators ( diaphragms ) are porosity, pore diameter, and thickness. For practical use, other aspects such as mechanical strength (brittle or flexible), constant dimensions (swelling in the solvent), and chemical stability are important. 

Depending on the size of the cell and the materials used in the separators, the optimal type of channel design, channel width and depth, and the wettability of the surfaces are different. Additionally, the current density and gas flow rates also affect the design. To establish general guidelines for optimal channel designs for these and related parameters, more research is still necessary. This section will present some results of the water behavior in cells and the characteristics of porous separators. 

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