Patent ID: 8187734

Claim:
A proton-conducting polymer composition comprising an aromatic hydrocarbon-based proton-conducting polymer and at least one solvent, wherein the content of said proton-conducting polymer is in the range of 1 to 30 mass %, wherein a component of said proton-conducting polymer having a molecular weight in the range of 2000 to 23000 in terms of polyethylene glycol accounts for at least 10 mass % of the total amount of said proton-conducting polymer, wherein said aromatic hydrocarbon-based proton-conducting polymer comprises a sulfonated polyarylene ether-based polymer, and wherein said aromatic hydrocarbon-based proton-conducting polymer comprises a component represented by the following formula (5) wherein Ar′ is selected from a bivalent aromatic group and Z is selected from direct bonding, ether bonding, and thioether bonding.