Polymer electrolyte for fuel cell

摘要

Provided is a polymer electrolyte which is cheap and easily synthesized, and has a high water resistance and high output performance. The polymer electrolyte comprising a sulfonated polymer having an ion-exchange group equivalent weight of 500 to 2500 g/mol, which is obtainable by sulfonating a structural unit represented by the structural formula (II) of a copolymer having 95 to 40 mol % of a structural unit represented by the following structural formula (I) and 5 to 60 mol % of a structural unit represented by the following structural formula (II),