Abstract: A method for purifying an aqueous sulfonylimide solution includes heating an aqueous sulfonylimide solution containing a sulfonylimide compound represented by the general formula (1). A method for producing a non-aqueous electrolyte solution includes adding an electrolyte solution solvent to the aqueous sulfonylimide solution purified by the purification method to dehydrate the aqueous sulfonylimide solution. A method for producing an electrolyte composition includes distilling off the electrolyte solution solvent from the non-aqueous electrolyte solution obtained by the production method.

Abstract: Disclosed is a method for producing a non-aqueous electrolyte solution containing a sulfonylimide compound represented by the general formula (1) and an electrolyte solution solvent (B). The method includes preparing a sulfonylimide solution containing the sulfonylimide compound represented by the general formula (1) and an electrolyte solution solvent (A) different from the electrolyte solution solvent (B) and fractionally distilling off the electrolyte solution solvent (A) by adding the electrolyte solution solvent (B) to the sulfonylimide solution obtained in the preparing, LiN(RSO2)(FSO2) (1) (where R represents a fluorine atom, an alkyl group with 1 to 6 carbon atoms, or a fluoroalkyl group with 1 to 6 carbon atoms).

Abstract: In a method for producing a composition containing an electrolyte, a non-aqueous solvent, and an anionic component, the electrolyte contains a sulfonylimide compound represented by the general formula (1), and the anionic component contains a conjugate acid with an acid dissociation constant pKa (a first-step acid dissociation constant pKa1 for acids that ionize multiple times) of 0 or more and 6.5 or less and is contained at a concentration of 10000 ppm by mass or less with respect to the electrolyte. The method includes dehydrating of adding the anionic component to a solution containing the electrolyte and the non-aqueous solvent to dehydrate the solution for solvent replacement. LiN (XSO2) (FSO2) (1) (where X represents a fluorine atom, an alkyl group with 1 to 6 carbon atoms, or a fluoroalkyl group with 1 to 6 carbon atoms).

Abstract: A method for storing a non-aqueous electrolyte solution containing a lithium salt in a sealed container, wherein at least one of carbon dioxide (CO2) or carbon monoxide (CO) occupying a gas phase part in the sealed container has a concentration of 10% or more.