Coolant membrane contamination

From the results achieved in the DECODE project, it can be concluded that the accumulation of cationic stainless steel corrosion products in the electrolyte membrane can be suppressed by proper design of the MEA, particularly by avoiding any contact of free electrolyte membrane with liquid water originating from the coolant or from condensate accumulated in the active area. Furthermore contact of corrosion inducing contaminants such as for example chloride ions with the metallic bipolar plates must be prevented. 

Figure 2a illustrates a representative bipolar plate with its associated inlet and outlet ports, and serpentine flow field channel. Figure 2b shows a generalized cross section of a complete unit ceU taken along the different lines indicated in Fig. 2a. The essential difference between these cross sections is the composition of the environment contacting the external part of the seal leading to either a port or the atmosphere (Fig. 2a). As a result of seal degradation or breakage, fuel or coolant can penetrate into the porous gas-diffusion electrode and subsequently the airstream. A similar situation can arise as a result of a bipolar plate or membrane breakage. Component failure is not a necessary requirement for the fuel stream to interact with the airstream since the membrane is permeable to gases, liquids, and cations. The airstream can also be contaminated by any fuel cell stack components...

Reduced contaminant concentration in the coolant in contact with the membrane leading to reduced penetration Contaminants reaching the fuel ceU reduced by adsorption on suitable materials... 

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