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.