Perfluorinated polymer electrolytes

Despite perfluorinated polymer electrolytes (Nafion, Flemion, Aciplex) having been used extensively in PEMFCs, their poor thermal mechanical stability (low Tg), high methanol permeability, and extremely high production costs have led to limitations of their large-scale application. Therefore, a variety of hydrocarbon polymer electrolytes have been developed during the past decade, with the greatest emphasis placed on the costs, conductivity, and durability of these materials. At the same time, the poor mechanical stability and inadequate durability of the hydrocarbon polymer membranes were identified as the main barriers to their practical application. 

On the contrary, the conductivity of perfluorinated polymer electrolytes usually appreciably decreases with increasing temperature, that is, the conductivity of such electrolytes at 80 °C is by an order of magnitude lower than... 

The absorbed water molecules are more strongly bound to alkylsulfonated rather than perfluorinated polymers. One can assume that this is related to the difference in the absorbtion mechanisms and to the physical state of absorbed water in PBI-PS and perfluorinated polymer electrolytes. 

Schiraldi DA (2006) Perfluorinated polymer electrolyte membrane durability. Polym Rev 46 315-327... 

To date, many membranes have been developed [3-12] and research has been carried out to develop a high performance membrane to replace perfluorinated polymer electrolyte membranes, such as Nafion membranes. However, no membranes developed to date satisfy aU of the above criteria required for DMFC membranes [2-12]. 

FIGURE 12.15 Chemical structures of perfluorinated polymer electrolyte membranes. (From Rikukawa, M. and Sanui, K., Progr. Polymer Sci. (Oxford), 25, 1463, 2000.)... 

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