Patent ID: 7414102

Claim:
A fuel cell, comprising: a polymer electrolyte of high durability comprising: a polymer chain which comprises a first repeating unit represented by a general formula —{C(Z 1 )(Z 2 )—C(Z 3 )(Z 4 —SO 3 H)}— wherein Z 1 , Z 2 , Z 3 , and Z 4 are respectively one of F and R f1 , F and R f2 , F and R f3 , and nothing and R f4 , wherein Z 1 , Z 2 and Z 3 are not simultaneously F; and each of R f1 to R f4 is a perfluoroalkyl group in which the carbon number is from 1 to 10 inclusive, wherein an equivalent weight is 2500 g/eq or less; wherein said polymer electrolyte has no ether linkage; wherein a deterioration with time is suppressed even when the polymer electrolyte is used under the operating condition of said fuel cell; and wherein the percentage of reduction in output voltage at 1000 hours of a durability test is not more than 50% of the percentage of reduction in output voltage at 1000 hours of a durability test of a wholly fluorinated electrolyte having an ether linkage.