Provided is a method with which it is possible to conveniently produce bis(fluorosulfonyl)imide suitable as a nonaqueous electrolyte of a lithium ion secondary cell. The method for producing a bis(fluorosulfonyl)imide alkali metal salt of the invention is a production method for producing a bis(fluorosulfonyl)imide alkali metal salt by reacting bis(fluorosulfonyl)imide and an alkali metal halide in a reaction solution including an organic solvent, the method including a purification step for filtering out the bis(fluorosulfonyl)imide alkali metal from the solution after the reaction.

Provided is a method with which it is possible to conveniently produce bis(fluorosulfonyl)imide suitable as a nonaqueous electrolyte of a lithium ion secondary cell. The method for producing a bis(fluorosulfonyl)imide alkali metal salt of the invention is a production method for producing a bis(fluorosulfonyl)imide alkali metal salt by reacting bis(fluorosulfonyl)imide and an alkali metal halide in a reaction solution including an organic solvent, the method including a purification step for filtering out the bis(fluorosulfonyl)imide alkali metal from the solution after the reaction.

A method for producing a bis(fluorosulfonyl)imide lithium salt is disclosed. The method includes the steps of: (a) reacting bis(chlorosulfonyl)imide with NH.sub.4F(HF)n (n=0-10) to prepare ammonium bis(fluorosulfonyl)imide; and (b) reacting the ammonium bis(fluorosulfonyl)imide with a lithium base, wherein in at least one of steps (a) and (b), after the reaction, a process of adding an alkoxy trialkyl silane to the reaction solution to remove a fluorine anion is performed.

A method for producing a bis(fluorosulfonyl)imide lithium salt is disclosed. The method includes the steps of: (a) reacting bis(chlorosulfonyl)imide with NH.sub.4F(HF)n (n=0-10) to prepare ammonium bis(fluorosulfonyl)imide; and (b) reacting the ammonium bis(fluorosulfonyl)imide with a lithium base, wherein in at least one of steps (a) and (b), after the reaction, a process of adding an alkoxy trialkyl silane to the reaction solution to remove a fluorine anion is performed.

A method for efficiently removing impurities such as sodium ions, fluoride ions, chloride ions and fluorosulfate ions without reducing the yield of a target product, including a fluorine-containing sulfonylamide compound selected from the group consisting of fluorine-containing sulfonylamide, a metal salt thereof, an ammonium salt thereof and a quaternary ammonium salt thereof is washed with an aqueous solution of salt of sulfuric acid.

To provide a composition in which when the composition is formed into a solution, the clogging of a filter is less likely to be caused, and the solution can be filtered in a short time. A composition comprising: lithium bis(fluorosulfonyl)imide; and an impurity, wherein when the composition is dissolved in a mixed solvent obtained by mixing ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7, to prepare a solution having a concentration of the lithium bis(fluorosulfonyl)imide of 1 M, and 50 mL of the solution is pressure-filtered at a pressure of 0.1 MPa using a membrane filter having a pore diameter of 0.2 m and a filtration area of 47 mm, insoluble particles having an average particle diameter of 5 to 150 m remain on the membrane filter.

A compound represented by the following formula (1):

##STR00001##

wherein R.sup.1, R.sup.2 and R.sup.3 each independently represent fluorine, an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms; and M.sup.+ represents an alkali metal ion.

The present invention relates to an electrolyte additive composition comprising lithium salt of bisfluorosulfonylimide and at least one selected from the group consisting of Cs.sup.+ ion and Rb ion.sup.+.

The present invention relates to an electrolyte additive composition comprising lithium salt of bisfluorosulfonylimide and at least one selected from the group consisting of Cs.sup.+ ion and Rb ion.sup.+.

The present invention provides a method for the production of a metal halide adduct of S.sub.4N.sub.4, in particular a specific copper adduct of S.sub.4N.sub.4, for the visualisation of a print on an object, in particular a fingerprint on a metal object. The present invention also provides a method and apparatus for visualising a print on an object, using S.sub.2N.sub.2 obtained from a metal halide adduct of S.sub.4N.sub.4.