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CATION EXCHANGE POLYMERIC MEMBRANES FOR FUEL CELLS

For the last 35 years, since the development of chemically stable cation exchange sulfonated polytetra-fluorethylene based perfluorinated membrane (Nafion) by Dupont, perfluorinated membranes are extensively used in PEM (Proton Exchange Membrane) fuel cells. But technical limitations, e.g. thermal stability, proton conductivity and membrane dehydration at higher temperature and higher cost of polymeric membrane, are the major hindrance in the commercialization of this technology. In the last 10 years, emphasis was to find the non fluorinated alternative membranes for use in PEM fuel cell with high proton conductivity, thermohydrolytic and chemical stability in aggressive fuel cell environment. The intention of this review is to provide an overview of progress made in the development of proton-conducting cation exchange membranes for use in PEMFC and DMFC and to describe the various approaches made to polymer synthesis and salient properties of the materials formed. The science and technology of proton conductivity in perfluorosulfonic acid membranes is discussed in detail. The most relevant literature in the field was surveyed and it was found that only a few nonfluorinated membrane materials are stable up to the above said requirement of PEMFC.