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 provides a method for producing a bis (fluorosulfonyl) imide alkali metal salt by a reaction of a mixture containing bis (fluorosulfonyl) imide and an alkali metal compound is provided. According to this method for producing a bis (fluorosulfonyl) imide alkali metal salt, a total of weight ratios of the bis (fluorosulfonyl) imide, the alkali metal compound and the bis (fluorosulfonyl) imide alkali metal salt to an entire reacted mixture is not less than 0.8, after the reaction.

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 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.

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 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.