Patent ID: 8273500

Claim:
A polymer electrolyte composition obtained by mixing a plurality of ion-conductive polymers, wherein the ion-conductive polymer that is highest in ion exchange capacity among the plurality of ion-conductive polymers is termed first ion-conductive polymer, and the ion-conductive polymer that is lowest in ion exchange capacity is termed second ion-conductive polymer, then the first ion-conductive polymer and the second ion-conductive polymer are both block copolymers composed of a segment having an ion-exchange group and a segment having substantially no ion-exchange groups, and if the weight fraction of the segment having an ion-exchange group in the first ion-conductive polymer is termed Wh1, and the weight fraction of the segment having an ion-exchange group in the second ion-conductive polymer is termed Wh2, then relations (I) and (II) listed below are satisfied; Wh1>Wh2 (I) Wh 1 −Wh 2≦0.25. (II)