Method for producing electrolyte solution, electrolyte solution, electrolyte membrane, electrode catalyst layer, membrane electrode assembly, and solid polymer electrolyte fuel cell

摘要

PROBLEM TO BE SOLVED: To provide: a method for manufacturing an electrolytic solution by which an electrolytic solution less in the amount of undissolved residue of fluorine-based polyelectrolyte, and lower in the concentration of fluorine ions included therein can be obtained; an electrolytic solution obtained by the method for manufacturing an electrolytic solution; and an electrolytic film, an electrode catalyst layer, and a fuel battery which are arranged by use of the electrolytic solution.SOLUTION: A method for manufacturing an electrolytic solution comprises a dissolving step of producing an electrolytic solution by dissolving, in a container, a fluorine-based polyelectrolyte including a SOX group (where X represents an alkali metal, an alkali-earth metal, or an NRRRR; and R, R, R, and Rindependently represent an alkyl group having 1-3 carbon atoms, or hydrogen), and a solvent including water. The dissolving step includes: increasing the pressure in the container by use of at least one kind of gas selected from a group consisting of nitrogen, helium, argon, oxygen, air, hydrogen, and carbon monoxide so as to exceed a saturation vapor pressure of the solvent; and raising the temperature in the container to a dissolution temperature, where the dissolution temperature is lower than the glass transition point of the fluorine-based polyelectrolyte.