The present disclosure relates to a new method for producing alkali salt of bis(fluorosulfonyl)imide of high purity, as industrial scale, and with a reasonable cost when compared to the other available methods. Said method comprises the steps of reacting a bis(chlorosulfonyl)imide or a salt thereof with an onium chloride to produce an onium salt of bis(chlorosulfonyl)imide; reacting an onium salt of bis(chlorosulfonyl)imide with anhydrous hydrogen fluoride in at least one organic solvent to produce onium salt of bis(fluorosulfonyl)imide; and reacting the onium salt of bis(fluorosulfonyl)imide with an alkali salt to obtain alkali salt of bis(fluorosulfonyl)imide.

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 present disclosure relates to a method for preparing salts of bis(fluorosulfonyl)imide and to a method for preparing alkali metal salts of bis(fluorosulfonyl)imide from said bis(fluorosulfonyl)imide salts. More specifically. the invention provides a new method for producing these salts of bis(fluorosulfonyl)imide which is implementable at industrial scale and providing high-purity bis(fluorosulfonyl)imide salts.

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.

The invention relates to a method for preparing bis(fluorosulfonyl)imide acid, comprising: the reaction of sulphamic acid or one of the salts thereof with a halogenosulfuric acid and at least one fluorinating agent selected from SOF.sub.2, FSO.sub.2F and SF.sub.4, and the subsequent recovery of bis(fluorosulfonyl)imide acid. The invention also relates to a method for producing salts of bis(fluorosulfonyl)imide from the bis(fluorosulfonyl)imide acid thus produced.

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.

The present invention provides an alkali metal salt of fluorosulfonyl imide having favorable heat resistance and a reduced content of specific impurities and a water content, and provides a method for producing an alkali metal salt of fluorosulfonyl imide, which is capable of easily removing a solvent from a reaction solution. An alkali metal salt of fluorosulfonyl imide of the present invention is represented by the following general formula (I) and has a mass loss rate of 2% or less when the alkali metal salt of fuluorosulufonyl imide is kept at 100 C. for 8 hours under an air current. A method for producing an alkali metal salt of fluorosulfonyl imide of the present invention comprises a step of concentrating a solution of the alkali metal salt of fulorosulfonyl imide by bubbling a gas into a reaction solution containing the alkali metal salt of fulorosulfonyl imide, and/or concentrating a solution of the alkali metal salt of fulorosulfonyl imide by thin layer distillation. ##STR00001##

The present invention provides a method for producing a fluorisulfonylimide salt, which enables reducing the impurity content and continuous operation for a long time, and a fluorosulfonyl imide salt. The fluorosulfonyl imide salt of the present invention has a K content of 10,000 ppm or less. The method for producing a fluorosulfonyl imide salt of the present invention is that after a fluorination reaction of chlorosulfonyl imde or a salt thereof, the reaction solution is brought into contact with an aqueous alkaline solution so as to remove impurities. The fluorosulfonyl imide salt of the present invention, in which various impirities are reduced to extremely low levels, is useful as an electrolyte used in a lithium secondary battery, a capacitor or the like, an ionic liquid, or an intermediate for a sulfonyl imide salt, and the like. It is expected that use of the fluorosulfonyl imide salt of the present invention as an electrolyte leads to a high-performance electrochemical device.

The present invention relates to a process for manufacturing a bis(chlorosulfonyl)imide (HCSI) of ultra-pure (UP) grade with a purity of at least 99.0 mol. % with respect to the total number of moles of HCSI. In addition, the present invention relates to an HCSI of UP grade obtainable from the process, and to the use of the HCSI of UP grade for preparing a lithium bis(fluorosulfonyl)imide (LiFSI). The present invention also relates to a process for manufacturing a LiFSI comprising the preparation of an HCSI of UP grade according to the present process. The present invention relates to a composition comprising a LiFSI with a purity of at least 99.99 mol. % with respect to the total number of moles of LiFSI in the composition, and to the use of a composition comprising a LiFSI obtainable from the present process in a lithium-ion secondary battery.

The present invention relates to a process for preparing a fluorosulfony limide salt. More specifically. the present invention relates to a process for preparing lithium bis(fluorosulfonyl)imide (LiFSI).