An object of the present invention is to provide a highly durable solid polymer
electrolyte that has a deterioration resistance equal to or higher than that of
the fluorine-containing solid polymer electrolytes or a deterioration resistance
sufficient for practical purposes, and can be produced at a low cost. According
to the present invention, there is provided a solid polymer electrolyte comprising
a polyether ether sulfone that is used as a electrolyte and has sulfoalkyl groups
bonded to its aromatic rings and represented by the general formula (CH2)nSO3H.
