Proton exchange membrane fuel cell hydrogen crossover

FIGURE 21.27 Hydrogen crossover current density under the long-term RH cycling comparison between Nafion cast membrane and reinforced membrane. (From Choudhury, B., Material challenges in proton exchange membrane fuel cells. International Symposium on Material Issues in a Hydrogen Economy, November 12-15, Richmond, VA, 2007.)... 

Chippar P, Oh K, Kim WG et al (2014) Numerical analysis of effects of gas crossover through membrane pinholes in high-temperature proton exchange membrane fuel cells. Int J Hydrogen Energy 39 2863-2871... 

The proton exchange membrane can be a source of fluoride ions as well [143]. Hydroxyl radicals, formed via crossover gases or reactions of hydrogen peroxide with Fenton-active contaminants (e.g., Fe +), could attack the backbone of Nafion, causing the release of fluoride anions these anions in turn promote corrosion of the fuel cell plates and catalyst, and release transition metals into the fuel cell [143]. Transition metal ions, such as Fe, then catalyze the formation of radicals within the Nafion membrane, resulting in a further release of fluoride anions. On the other hand, transition metal ions also can cause decreased membrane and ionomer conductivity in catalyst layers, as discussed in section 2.4 of this chapter. 

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