The present invention relates to a method for preparing a lithium bis(fluorosulfonyl)imide salt, including a step of dissolving bis(chlorosulfonyl)imide in an organic solvent in a non-glass vessel to prepare a first reaction solution; a step of injecting lithium fluoride (LiF) to the first reaction solution in the non-glass vessel and refluxing while heating to prepare a second reaction solution; a step of separating a product including a lithium bis(fluorosulfonyl)imide salt and the organic solvent from the second reaction solution; and a step of obtaining the lithium bis(fluorosulfonyl)imide salt in a solid phase from the product, wherein the organic solvent is at least one or more selected from the group consisting of ethyl acetate, butyl acetate, chloroform, dichloromethane, dichloroethane, benzene, xylene and acetonitrile.

A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.

A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.

A method for preparing Cl—SO.sub.2NHSO.sub.2Cl including a step of chlorinating sulphamic acid with at least one chlorinating agent and at least one sulphur-containing agent, the method resulting in a flow F1, preferably liquid, including Cl—SO.sub.2NHSO.sub.2Cl and a gas stream F2 including HCl and SO.sub.2, the method including a step a) of treating the gas stream F2. Also, a method for preparing LiFSl including the abovementioned method for preparing Cl—SO.sub.2NHSO.sub.2Cl.

A process for producing high purity lithium bis(fluorosulfonyl) imide includes contacting bis(fluorosulfonyl) imide with a lithium salt, followed by purification and drying of lithium bis(fluorosulfonyl) imide.

A process for producing high purity lithium bis(fluorosulfonyl) imide includes contacting bis(fluorosulfonyl) imide with a lithium salt, followed by purification and drying of lithium bis(fluorosulfonyl) imide.

A fluorination process for obtaining fluorinated compounds including at least one fluorosulfonyl group. More particularly, a process for preparing a fluorinated compound of formula (II), including at least one step of reacting a compound of formula (I) with anhydrous hydrofluoric acid in at least one organic solvent, in which R1 is equal to R2 except in the specific case where R1═Cl, then R2═F, and when R1 is equal to R2, R1 and R2 represent an electron-withdrawing group which has a Hammett parameter σp of greater than 0, such as F, CF.sub.3, CHF.sub.2, CH.sub.2F, C.sub.2HF.sub.4, C.sub.2H.sub.2F.sub.3, C.sub.2H.sub.3F.sub.2, C.sub.2F.sub.5, C.sub.3F.sub.7, C.sub.3H.sub.2F.sub.5, C.sub.3H.sub.4F.sub.3, C.sub.3HF.sub.6, C.sub.4F.sub.9, C.sub.4H.sub.2F.sub.7, C.sub.4H.sub.4F.sub.5, C.sub.5F.sub.11, C.sub.3F.sub.5OCF.sub.3, C.sub.2F.sub.4OCF.sub.3, C.sub.2H.sub.2F.sub.2OCF.sub.3, CF.sub.2OCF.sub.3, C.sub.6F.sub.13, C.sub.7F.sub.15, C.sub.8F.sub.17 or C.sub.9F.sub.19, and M represents a hydrogen atom, an alkali metal, an alkaline-earth metal or a quaternary ammonium cation.

A fluorination process for obtaining fluorinated compounds including at least one fluorosulfonyl group. More particularly, a process for preparing a fluorinated compound of formula (II), including at least one step of reacting a compound of formula (I) with anhydrous hydrofluoric acid in at least one organic solvent, in which R1 is equal to R2 except in the specific case where R1═Cl, then R2═F, and when R1 is equal to R2, R1 and R2 represent an electron-withdrawing group which has a Hammett parameter σp of greater than 0, such as F, CF.sub.3, CHF.sub.2, CH.sub.2F, C.sub.2HF.sub.4, C.sub.2H.sub.2F.sub.3, C.sub.2H.sub.3F.sub.2, C.sub.2F.sub.5, C.sub.3F.sub.7, C.sub.3H.sub.2F.sub.5, C.sub.3H.sub.4F.sub.3, C.sub.3HF.sub.6, C.sub.4F.sub.9, C.sub.4H.sub.2F.sub.7, C.sub.4H.sub.4F.sub.5, C.sub.5F.sub.11, C.sub.3F.sub.5OCF.sub.3, C.sub.2F.sub.4OCF.sub.3, C.sub.2H.sub.2F.sub.2OCF.sub.3, CF.sub.2OCF.sub.3, C.sub.6F.sub.13, C.sub.7F.sub.15, C.sub.8F.sub.17 or C.sub.9F.sub.19, and M represents a hydrogen atom, an alkali metal, an alkaline-earth metal or a quaternary ammonium cation.

The present invention provides: a nonaqueous electrolyte solution which is used in a nonaqueous electrolyte battery having a low initial resistance value; and a compound which is contained in this nonaqueous electrolyte solution. A nonaqueous electrolyte solution according to the present invention contains a compound represented by formula (1), a solute and a nonaqueous organic solvent. In general formula (1), each of R.sup.1 and R.sup.2 represents PO(R.sub.f).sub.2 or SO.sub.2R.sub.f, and Rf represents, for example, a fluorine atom; each of R.sup.3 and R.sup.4 represents, for example, a lithium ion, or alternatively R.sup.3 and R.sup.4 may form a ring structure together with a nitrogen atom to which the moieties are bonded, and in this case, R.sup.3 and R.sup.4 form an alkylene group in combination with each other; an oxygen atom may be contained between carbon atom-carbon atom bonds in the alkylene group; a side chain thereof may have an alkyl group; and an arbitrary hydrogen atom in the alkyl group and the alkylene group may be substituted by a fluorine atom.

Provided is a novel imidic acid compound having a divalent anion useful as a pharmaceutical intermediate, an agrochemical intermediate, an acid catalyst, a battery electrolyte or an antistatic agent. The imidic acid compound is a divalent imidic acid compound represented by the following general formula (1) or (2).

##STR00001##

[In formulae (1) and (2), R.sup.1 to R.sup.3 represent a fluorine atom or an organic groups selected from a linear or branched C1-10 alkoxy group, a C2-10 alkenyloxy group, a C2-10 alkynyloxy group, a C3-10 cycloalkoxy group, a C3-10 cycloalkenyloxy group and a C6-10 aryloxy group, and wherein a fluorine atom, an oxygen atom or an unsaturated bond may also be present in the organic group. M.sup.1 and M.sup.2 represent protons, metal cations or onium cations.]