A method for producing a lithium bis(fluorosulfonyl)imide salt F—(SO.sub.2)—NLi—(SO.sub.2)—F, comprising a step comprising a step of chlorination of sulfamic acid HO—(SO.sub.2)—NH.sub.2 in order to obtain the bis(chlorosulfonyl)imide Cl—(SO.sub.2)—NH—(SO.sub.2)—Cl, said step being carried out in a reactor made of a corrosion-resistant material M3, or in a reactor containing a base layer made of a material M1 coated with a surface layer made of a corrosion-resistant material M2.

Methods of removing target impurities from a crude lithium bis(fluorosulfonyl)imide (LiFSI) to make a purified LiFSI product. In some embodiments, a purification method includes contacting crude LiFSI with a first anhydrous organic solvent to create a solution containing LiFSI and the target impurity(ies), wherein the LiFSI is soluble and the impurity(ies) is/are substantially insoluble. In some embodiments, a second anhydrous organic solvent is added to the solution to precipitate the target impurity(ies), which is then filtered to obtain a filtrate. In some embodiments, solvent is removed from the filtrate to obtain a solid mass containing LiFSI, which may then be contacted with a third anhydrous organic solvent in which the LiFSI is insoluble. The LiFSI may then be isolated from the third anhydrous organic solvent to obtain the purified LiFSI product. Also disclosed are purified LiFSI products and electrochemical devices utilizing purified LiFSI products, among other things.

The invention relates to a process for purifying a lithium bis(fluorosulfonyl)imide salt. The present invention relates to a process for purifying a lithium bis(fluorosulfonyl)imide salt in a solution in at least one solvent S1, said process comprising at least one purification step carried out in:a piece of silicon carbide-based or fluorinated polymer-based equipment; ora piece of metal or glass equipment comprising an inner surface, said inner surface, which can come into contact with the lithium bis(fluorosulfonyl)imide salt, being covered with a polymer coating or with a silicon carbide coating.

Provided is a method the enables easy production of bis(fluorosulfonyl)imide suitable for a non-aqueous electrolytic solution for a lithium ion secondary battery, etc. The method for producing a bis(fluorosulfonyl)imide alkali metal salt according to the present invention comprises reacting bis(fluorosulfonyl)imide with an alkali metal compound in a reaction solution containing an organic solvent, wherein the organic solvent includes at least one organic solvent (A) selected from the group consisting of carbonate solvents, cyclic ether solvents, linear ether solvents having two or more oxygen atoms in the molecule, cyclic ester solvents, sulfolane solvents, N,N-dimethyl formamide, dimethyl sulfoxide, and N-methyl oxazolidinone.

Methods of removing target impurities from a crude lithium bis(fluorosulfonyl)imide (LiFSI) to make a purified LiFSI product. In some embodiments, a purification method includes contacting crude LiFSI with a first anhydrous organic solvent to create a solution containing LiFSI and the target impurity(ies), wherein the LiFSI is soluble and the impurity(ies) is/are substantially insoluble. In some embodiments, a second anhydrous organic solvent is added to the solution to precipitate the target impurity(ies), which is then filtered to obtain a filtrate. In some embodiments, solvent is removed from the filtrate to obtain a solid mass containing LiFSI, which may then be contacted with a third anhydrous organic solvent in which the LiFSI is insoluble. The LiFSI may then be isolated from the third anhydrous organic solvent to obtain the purified LiFSI product. Also disclosed are purified LiFSI products and electrochemical devices utilizing purified LiFSI products, among other things.

A method for preparing hydrogen bis(fluorosulfonyl)imide including contacting sulfonyl fluoride with hexamethyl disilazane in an organic solvent. The disclosure also provides a method for preparing lithium bis(fluorosulfonyl)imide (LiFSI). The method includes contacting sulfonyl fluoride with hexamethyl disilazane in an organic solvent and yielding hydrogen bis(fluorosulfonyl)imide; and contacting hydrogen bis(fluorosulfonyl)imide with a lithium compound and yielding lithium bis(fluorosulfonyl)imide.

A method for recovering lithium bis(fluorosulfonyl)imide is provided in the present application. The method of the present application may comprise: mixing a slag from lithium bis(fluorosulfonyl)imide production process with a solvent of carbonate ester, to obtain a mixed material; subjecting the mixed material to solid-liquid separation, to obtain a discharged liquid and a solid slag; monitoring the chromaticity of the discharged liquid and comparing the chromaticity of the discharged liquid with a chromaticity reference; recycling the discharged liquid to the mixed material, if the chromaticity of the discharged liquid is higher than the chromaticity reference; and recycling the discharged liquid to lithium bis(fluorosulfonyl)imide production process, if the chromaticity of the discharged liquid is lower than or equal to the chromaticity reference.

The present invention relates to a method for drying and purifying a lithium bis(fluorosulfonyl)imide salt in solution in an organic solvent S1, said method comprising the following steps: a) adding deionised water to dissolve and extract the lithium bis(fluorosulfonyl)imide salt, forming an aqueous solution of said salt; b) extracting the lithium bis(fluorosulfonyl)imide salt from said aqueous solution, using an organic solvent S2, said step being repeated at least once; c) concentrating the lithium bis(fluorosulfonyl)imide salt by evaporating said organic solvent S2 and the water, in a short-path thin-film evaporator, under the following conditions: temperature of 30 C. to 95 C., pressure of 10.sup.3 mbar abs to 5 mbar abs, residence time no longer than 15 min; and d) optionally crystallising the lithium bis(fluorosulfonyl)imide salt. The present invention likewise relates to a composition made of lithium bis(fluorosulfonyl)imide salt, and the uses thereof in Li-ion batteries.

Provided is a method the enables easy production of bis(fluorosulfonyl)imide suitable for a non-aqueous electrolytic solution for a lithium ion secondary battery, etc. The method for producing a bis(fluorosulfonyl)imide alkali metal salt according to the present invention comprises reacting bis(fluorosulfonyl)imide with an alkali metal compound in a reaction solution containing an organic solvent, wherein the organic solvent includes at least one organic solvent (A) selected from the group consisting of carbonate solvents, cyclic ether solvents, linear ether solvents having two or more oxygen atoms in the molecule, cyclic ester solvents, sulfolane solvents, N,N-dimethyl formamide, dimethyl sulfoxide, and N-methyl oxazolidinone.

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.