The present invention relates to bis(fluorosulfonyl)imide salts, and their preparation methods. More specifically, the invention provides a new salt of bis(fluorosulfonyl)imide containing from 0.01 ppm to 10000 ppm of a halogenated alcohol. The invention further relates to a method for producing said salt of bis(fluorosulfonyl)imide, said method comprising a step of crystallizing a raw salt of bis(fluorosulfonyl)imide within a crystallization solvent comprising at least a halogenated alcohol. The use of said salt of bis(fluorosulfonyl)imide is also disclosed.

Granules or powders consisting of a compound of formula [I], in which a modal diameter is 80 m or less, a median diameter is 45 m or less, and/or, a ratio of (modal diameter)/(median diameter) is 1.7 or less, are preferably used for an electrolyte or the like. ##STR00001## In formula [I], R.sup.1 and R.sup.2 each independently represents a fluoroalkyl group having 1 to 6 carbon atoms, or a fluorine atom, and Y.sup.+ represents an alkali metal cation or an ammonium cation.

Granules or powders consisting of a compound of formula [I], in which a modal diameter is 80 m or less, a median diameter is 45 m or less, and/or, a ratio of (modal diameter)/(median diameter) is 1.7 or less, are preferably used for an electrolyte or the like. ##STR00001## In formula [I], R.sup.1 and R.sup.2 each independently represents a fluoroalkyl group having 1 to 6 carbon atoms, or a fluorine atom, and Y.sup.+ represents an alkali metal cation or an ammonium cation.

The present invention relates to a novel method for preparing lithium bis(fluorosulfonyl)imide and, more specifically, to a method for preparing lithium bis(fluorosulfonyl)imide, capable of simply and economically preparing lithium bis(fluorosulfonyl)imide, which is a lithium salt to be used in an electrolyte solution for a lithium secondary battery, in a high yield and with high purity. According to the present invention, the novel method for preparing lithium bis(fluorosulfonyl)imide can resolve the problem of a conventional technique by reacting a bis(chlorosulfonyl)imide compound, which is a starting material, with a fluorination reagent, and then immediately treating the same with an alkali reagent without purification or concentration, and has an effect of enabling lithium bis(fluorosulfonyl)imide to be simply and economically prepared in a high yield and with high purity.

The present invention relates to a novel method for preparing lithium bis(fluorosulfonyl)imide and, more specifically, to a method for preparing lithium bis(fluorosulfonyl)imide, capable of simply and economically preparing lithium bis(fluorosulfonyl)imide, which is a lithium salt to be used in an electrolyte solution for a lithium secondary battery, in a high yield and with high purity. According to the present invention, the novel method for preparing lithium bis(fluorosulfonyl)imide can resolve the problem of a conventional technique by reacting a bis(chlorosulfonyl)imide compound, which is a starting material, with a fluorination reagent, and then immediately treating the same with an alkali reagent without purification or concentration, and has an effect of enabling lithium bis(fluorosulfonyl)imide to be simply and economically prepared in a high yield and with high purity.

A process for preparing a fluoro compound of formula: R.sub.2(SO.sub.2)NX(SO.sub.2)F (III) including: (a) a first step for obtaining the chloro compound of formula: R.sub.1(SO.sub.2)NX(SO.sub.2)Cl; (II) this first step including the reaction of the sulfamide of formula: R.sub.0(SO.sub.2)NH.sub.2 (I) with a sulfurous acid and a chlorinating agent; and (b) a second step for obtaining the fluoro compound of formula (III), this second step including the reaction of the chloro compound of formula (II) with anhydrous hydrofluoric acid in at least one organic solvent; in which: X represents either a hydrogen atom or a monovalent cation M; R.sub.1 represents an electron-withdrawing group having a positive Hammett parameter .sub.p; if R.sub.1 represents Cl, then R.sub.0 represents OH; otherwise, R.sub.0 is identical to R.sub.1; and if R.sub.1 represents Cl, then R.sub.2 represents F; otherwise, R.sub.2 is identical to R.sub.1.

A process for preparing a fluoro compound of formula: R.sub.2(SO.sub.2)NX(SO.sub.2)F (III) including: (a) a first step for obtaining the chloro compound of formula: R.sub.1(SO.sub.2)NX(SO.sub.2)Cl; (II) this first step including the reaction of the sulfamide of formula: R.sub.0(SO.sub.2)NH.sub.2 (I) with a sulfurous acid and a chlorinating agent; and (b) a second step for obtaining the fluoro compound of formula (III), this second step including the reaction of the chloro compound of formula (II) with anhydrous hydrofluoric acid in at least one organic solvent; in which: X represents either a hydrogen atom or a monovalent cation M; R.sub.1 represents an electron-withdrawing group having a positive Hammett parameter .sub.p; if R.sub.1 represents Cl, then R.sub.0 represents OH; otherwise, R.sub.0 is identical to R.sub.1; and if R.sub.1 represents Cl, then R.sub.2 represents F; otherwise, R.sub.2 is identical to R.sub.1.

The invention relates to a method for the preparation of bis(fluorosulfonyl)-imide, the method starts from bis(chlorosulfonyl)-imide or its respective derivatives, which is reacted with HF in the presence of chlorosulfonyl isocyanate, and uses a certain extraction step for extraction of bis(fluorosulfonyl)-imide from an aqueous solution; the invention is also useful for the preparation of certain salts of bis(fluorosulfonyl)-imide and its derivatives.

The invention relates to a method for the preparation of bis(fluorosulfonyl)-imide, the method starts from bis(chlorosulfonyl)-imide or its respective derivatives, which is reacted with HF in the presence of chlorosulfonyl isocyanate, and uses a certain extraction step for extraction of bis(fluorosulfonyl)-imide from an aqueous solution; the invention is also useful for the preparation of certain salts of bis(fluorosulfonyl)-imide and its derivatives.

A method of purifying a crude lithium bis(fluorosulfonyl)imide, includes adding a water removal agent to a pretreatment liquid containing the crude lithium bis(fluorosulfonyl)imide to perform a dehydration reaction at a temperature ranging from 20? ? C. to 40? C., reacting the same for an additional 1 h to 6 h after an acid gas stops escaping from the reaction system, and filtering the reaction system to obtain a filtrate; the water removal agent is bismuth trichloride or antimony trichloride. Evaporating and concentrating the filtrate, and recrystallizing the concentrated filtrate are performed to obtain a purified lithium bis(fluorosulfonyl)imide.