Patent ID: 7396608

Claim:
A polymer electrolyte containing a block copolymer comprising one or more blocks having sulfonic acid groups and one or more blocks having substantially no sulfonic acid group, and at least one block among all the blocks is a block having aromatic rings in the main chain thereof, wherein the one or more blocks having substantially no sulfonic acid group is/are introduced from precursors having a weight-average molecular weight of not less 2000, and wherein the blocks having substantially no sulfonic acid group are aromatic polyethers having a repeating unit represented by the general formula [4]: in the formula, R 4 represents an alkyl group having 1 to 6 carbon atoms; f is an integer from 0 to 4; when a plurality of R 4 s are present, these may be the same or different; and Z represents —CO— or —SO 2 —.