Method for manufacturing electrolyte solution material

A method for producing an electrolyte solution containing a fluorosulfonyl imide salt represented by the following general formula (1) and an electrolyte solution solvent, said method comprising decompressing and/or heating a solution containing the fluorosulfonyl imide salt, the electrolyte solution solvent and a fluorosulfonyl imide salt production solvent to volatilize the fluorosulfonyl imide salt production solvent,

• wherein:
• R1 represents a fluorine atom or fluorinated alkyl group having 1 to 6 carbon atoms;
• R2 represents an alkali metal ion;
• and the electrolyte solution solvent is at least one selected from the group consisting of a carbonate-based solvent, a linear ether-based solvent, and a cyclic ester based solvent,
• thereby producing the electrolyte solution,
• wherein the fluorosulfonyl imide salt production solvent is at least one selected from the group consisting of an alcohol-based solvent, a carboxylic acid-based solvent, a ketone, a nitrile-based solvent, an ester-based solvent, an aliphatic ether-based solvent, a halogen-based solvent, a nitro-group-containing solvent, a nitrogenated organic solvent, and a glyme-based solvent, and
• wherein a reduced pressure in the volatilization step is 200 kPa or less, and a volatilization temperature is 20° C. to 60° C.