Patent ID: 8455141

Claim:
A polymer electrolyte comprising a non-crosslinking proton conductive polymer (A) and a non proton conductive cross linking polymer (B), the proton conductive polymer (A) is a non-perfluorinated proton conductive polymer, and cross linking polymer (B) comprises a moiety selected from the group consisting of a radical polymerizing polymer, an epoxy based polymer, a melamine based polymer, a phenol resin based polymer, a urethane based polymer, a urea based polymer and an inorganic cross linking polymer, wherein a ratio of the amount of unfreezable water, represented by formula (S1), in said polymer electrolyte is no less than 40 wt % and no greater than 100 wt %, wherein the ratio of amount of unfreezable water (S1)=(amount of unfreezable water)/(amount of low melting point water+amount of unfreezable water)×100 (%) and wherein the ratio of the amount of unfreezable water in the polymer electrolyte to the weight of the polymer electrolyte when dried, which is represented by formula (S2), is no less than 20% and no higher than 200%, wherein the content of unfreezable water (S2)=(amount of unfreezable water in polymer electrolyte)/(weight of polymer electrolyte when dried)×100(%).