Anion exchange membranes, disadvantages

Recent developments in AAEMs have opened up the possibiUty of an alkaline analog of the acidic solid polymer electrolyte fuel cell. This could utilize the benefits of the alkaline cathode kinetics and at the same time eradicate the disadvantages of using an aqueous electrolyte. As the AAEM is also a polymer electrolyte membrane (sometimes abbreviated as PEM), some clarity in abbreviations is required. In this chapter, PEM refers only to the proton exchange membrane fuel cells (acidic), AAEM refers to the anion exchange membrane H2/O2 fuel cells, and AFC exclusively refers to the aqueous electrolyte alkaline H2/O2 fuel cells. Anion exchange membranes are also employed in alkaline direct alcohol fuel cells, discussion of which will refer to them as ADMFC/ADEFC (methanol/ ethanol). 

A cation exchange membrane was developed to overcome these disadvantages. This membrane allows continuous regeneration and consists of a sulfonated polyethylene derivative. It is resistant to water-miscible organic solvents and exhibits a high permeability for quaternary ammonium bases such as tetrabutylammonium hydroxide. Hence, the suppression mechanism differs substantially from the process for anion exchange chromatography described in Section 3.3.3. 

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