Electrolyte material for polymer electrolyte fuel cells, electrolyte membrane and membrane/electrode assembly

Abstract

To provide a polymer electrolyte material for polymer electrolyte fuel cells, which is an electrolyte material having a high ion exchange capacity and a low resistance, and which has a higher softening temperature than a conventional electrolyte material. An electrolyte material for polymer electrolyte fuel cells, which is made of a polymer containing repeating units based on a fluoromonomer having a radical polymerization reactivity, wherein the repeating units contain, in their side chains, a structure having ionic groups represented in the following formula (α) (provided that in the formula, each of Qand Qwhich are independent of each other, is a single bond or a perfluoroalkylene group that may have an etheric oxygen atom, provided that they are not single bonds at the same time, Ris a perfluoroalkyl group which may have an etheric oxygen atom, and X is an oxygen atom, a nitrogen atom or a carbon atom, provided that when X is an oxygen atom, a=0, when X is a nitrogen atom, a=1, and when X is a carbon atom, a=2, and Y is a fluorine atom or a monovalent perfluoro organic group).