Perfluorinated sulfonic acid membranes

Short Side Chain Perfluorinated Sulfonic Acid Membranes.782... 

FCs must cost around 45/kW to be competitive with the internal combustion engine. Perfluorinated sulfonic acid membranes currently cost 100-200/KW resulting in PEM FC prices estimated to be of the order of 1000/KW. 

The perfluorinated sulfonic acid membrane exhibits a very strong acidic behavior in water. As shown in Figure 6, the concentration of fixed ion for Nafion of 1200 EW in E-form is equivalent to 13 wt % sulfuric acid. A similar value of 10 wt % sulfuric acid was observed by LaConti et The value is a good indication of the acidity of a material. A recent study has reported that " the... 

Figure 4. Ionic clusters formed in perfluorinated sulfonic acid membrane.

A recent study has shown that (58) membranes with carboxylic acid groups cannot be used without alkaline supporting electrolyte because of low swelling and poor conductivity in pure water. It is clear that the alternate membrane for the SPE cell should be a perfluorinated sulfonic acid membrane. To date (1981), Nafion still retains its uniqueness for this electrochemical application. 

Inaba M (2009) Chemical degradation of perfluorinated sulfonic acid membranes. In Buechi EN, Inaba M, Schmidt TJ (eds) Polymer electrolyte fuel cell durability. Springer, New York... 

For preparation of acid-base membranes of this type, the used polyacids include polycar-boxylic acids, polyphosphonic acid, polysulfonic acid, as well as perfluorinated sulfonic acid membranes. Carboxylic acids and phosphoric acid are weak acids with pK ranging from 2 to 5 (see Fig. 3.1), showing a low proton conductivity of 10 S cm level in its crystalline state. When blended with a stronger base than water, e.g., benzimidazole, a high conductivity of 4 X 10 S cm was reported at 130 °C [78]. Bozkurt et al. [79] prepared polyacrylic... 

Malfunction of Phosphoric Acid-Doped Perfluorinated Sulfonic Acid Membranes... 

Compared with perfluorinated sulfonic acid membranes, sulfonated poly(aryl ether ketone) is reported to have a smaller characteristic sq>aration length and wida distribution with more dead-end channels and a largo- internal interface between the... 

Fig. 1 Chemical structures of commerdaUy available perfluorinated sulfonic acid membranes...

Specifically, the conductivity of m-PBI was investigated as a function of doping electrolyte [9-11,15-18], and was nicely discussed by Schuster and Meyer [19]. Overall, it was found that m-PBI with a doping level between 2-8 moles PA/PRU typically has a conductivity between 10 and 10 S cm in low humidification or nonhumidified conditions at high temperatures (>120 °C). hi general, for the m-PBI/sulfuric acid complex, conductivities were similar to the m-PBI/PA complex or slightly lower [10,11,16,17]. The higher values are comparable to the current state of the art perfluorinated sulfonic acid membrane (Nafion) at atmospheric pressure and full hydration. However, the m-PBI/PA complex is the most widely studied, because of its conductivity and thermal stability. 

Nafion, a perfluorinated sulfonic acid membrane (Fig. 7) is often considered the state of the art membrane for fuel cells operating at temperatures below about 80 °C. Because the acid fimctionahty in the presence of water is ne-... 

DLFCs can use a cation exchange membrane (CEM) or an anion exchange membrane as an electrolyte, the principles of which are shown in Fig. 6.1a and b. DLFCs that use acidic and alkaline reaction media correspond to the CEM and AEM types, respectively. Perfluorinated sulfonic acid membranes, that is, Nafion , are typical CEMs, in which a countercation of sulfonate can be exchanged for another... 

Rodgers, M. R, BonviUe, L. J., Kunz, H. R., Slattery, D. K., Fenton, J. M., Fuel cell perfluorinated sulfonic acid membrane degradation correlating accelerated stress testing and lifetime. Chem. Rev. 2012,112 (11), 6075-6103. 

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