JP2008266155A - Method for producing sulfonimide lithium salt - Google Patents

Abstract

The present invention provides a novel process for producing a sulfonimide lithium salt which is a substance useful as an electrolyte for a storage element such as a lithium ion secondary battery.
A sulfonimide lithium salt is produced by mixing and stirring a sulfonimide acid salt and an inorganic lithium salt.
[Selection figure] None

Description

  The present invention relates to a method for producing a sulfonimide lithium salt, which is a substance useful as an organic ion conductor.

The sulfonimide lithium salt is a substance useful as an electrolyte for a storage element such as a lithium ion secondary battery because it has good ion conductivity, thermal stability, and chemical stability.
As a method for producing a sulfonimide lithium salt, a method in which a sulfonimide salt different from a lithium salt is once synthesized from a sulfonyl halide and a sulfonamide and then converted into a sulfonimide lithium salt is known (for example, Patent Documents 1 to 3). 3, Non-Patent Document 1).
Specifically, as shown in the following synthesis route a, a sulfonimidate is once synthesized from a sulfonyl halide and a sulfonamide, then concentrated sulfuric acid is added to the sulfonimidate, and a sulfonimide acid is obtained by distillation operation. There is a method of reacting with lithium hydroxide or lithium carbonate after isolation (for example, Patent Documents 1 and 2).

However, since the above synthesis method (route a) must pass through a sulfonimidic acid which is a super strong acid, special reaction equipment is required, and furthermore, the reaction operation becomes complicated, which is industrial. It is hard to say that it is a manufacturing method.
On the other hand, as a method that does not pass through a sulfonimidic acid that is a super strong acid, for example, as shown in the above synthesis method (route b), lithium hydroxide is reacted with an amine salt of sulfonimidic acid to exchange amine and lithium There is a method of obtaining a sulfonimide lithium salt by liberating an amine by reaction (for example, Patent Document 3, Non-Patent Document 1).

However, even in the above synthesis method (route b), when the amine salt of sulfonimide acid is reacted with lithium hydroxide, the amine is liberated, so there are work environment countermeasures and abatement equipment for the amine odor. Necessary.
Thus, it is difficult to say that the conventional method for producing a sulfonimide lithium salt is an industrial production method, and development of a method for producing a sulfonimide lithium salt that is industrially excellent in operability has been desired.
US Pat. No. 5,874,616 JP 2001-288193 A JP-A-8-81436 Journal of Fluorine Chemistry 125, 243-252 (2004)

  In view of the above problems, an object of the present invention is to provide a method for producing a sulfonimide lithium salt by a synthetic route that is simple and excellent in operability without requiring special equipment.

As a result of intensive studies to solve the above problems, the present inventors have found that sulfonimide lithium salt can be obtained in high yield by reacting sulfonimide salt with inorganic lithium salt. It came to be completed.
That is, the present invention is as follows.

[1] The following general formula (1)
Rf ¹ SO ₂ N (M) SO ₂ Rf ² (1)
(Rf ¹ and Rf ² are each independently a fluorinated hydrocarbon group having 1 to 12 carbon atoms or a substituent thereof, M is Ma, Mb _1/2 , Ma is an alkali metal other than lithium, and Mb is Alkaline earth metal.)
A sulfonimide salt represented by the following general formula (2)
Li _m X (2)
(M is 1 or 2, and X is an anion selected from halide ions, hydroxide ions, carbonate ions, perchlorate ions, and sulfate ions.)
It is made to mix and stir with the inorganic lithium salt represented by the following general formula (3)
Rf ¹ SO ₂ N (Li) SO ₂ Rf ² (3)
^(Rf 1, Rf ² is the same as ^Rf 1, Rf ² in formula (1).)
The manufacturing method of the sulfonimide lithium salt represented by these.

[2] The method according to [1], wherein in the general formula (1), M is sodium or potassium.
[3] The production method according to [1] or [2], wherein in the general formula (2), X is a halide ion.

  ADVANTAGE OF THE INVENTION According to this invention, the sulfonimide lithium salt which is a substance useful as an electrolyte of a lithium ion secondary battery can be manufactured with a simple apparatus with a sufficient yield.

The present invention will be described in detail below.
The present invention relates to a method for producing a sulfonimide lithium salt by mixing and stirring a sulfonimide salt with an inorganic lithium salt.
First, the following general formula (1) used as a starting material in the present invention.
Rf ¹ SO ₂ N (M) SO ₂ Rf ² (1)
The sulfonimide salt represented by the formula is described.
In the general formula (1), Rf ¹ and Rf ² are each independently a fluorinated hydrocarbon group having 1 to 12 carbon atoms or a substituted product thereof.

The fluorinated hydrocarbon group may be a linear structure, a branched structure, or a cyclic structure as a molecular structure, and represents a fully fluorinated or partially fluorinated hydrocarbon group. Further, the substituent may include a) a halogen group such as a chlorine atom and a bromine atom, and b) an ether group.
When Rf ¹ and Rf ² contain an ether bond, the ratio of [number of ether bonds] / [number of carbon atoms] is preferably 0.5 or less, more preferably 0.35 or less, and still more preferably Is 0.25 or less. If the ratio of [number of ether bonds] / [number of carbon atoms] is too large, the stability of Rf ¹ and Rf ² is lowered, which is not preferable.
Specific examples of Rf ¹ and Rf ² include the following.

1, an example of a perfluorinated hydrocarbon radical _{CF 3 -, CF 3 CF 2} -, CF 3 CF 2 CF 2 -, CF 3 CF (CF 3) -, CF 3 CF 2 CF 2 CF 2 -,
_{CF 3 CF (CF 3) CF} 2 -, CF 3 CF 2 CF (CF 3) -, CF 3 (CF 2) 5 -, CF 3 (CF 2) 7 -,

2, Examples of hydrogen atom-containing fluorinated hydrocarbon groups HCF _2- , HCF ₂ CF _2- , CF ₃ CHF-, HCF ₂ CF ₂ CF _2- , CF ₃ CHFCF _2- ,
_{CF 3 CF 2 CFH-, HCF 2} CF 2 CF 2 CF 2 -, CF 3 CFHCF 2 CF 2 -, CF 3 CF 2 CFHCF 2 -,
CF ₃ CF ₂ CF ₂ CFH-,

3, examples of the halogen-containing fluorinated hydrocarbon group _{ClCF 2 -, BrCF 2 -,} ClCF 2 CF 2 -, BrCF 2 CF 2 -, ClCF 2 CF 2 CF 2 CF 2 -,
BrCF ₂ CF ₂ CF ₂ CF _2- , ClCF ₂ CFClCF ₂ CF _2- ,

4, examples of ether group-containing fluorinated hydrocarbon groups CF ₃ CFHO (CF ₂ ) ₂ —, CF ₃ CFHO (CF ₂ ) ₃ —, CF ₃ CFHO (CF ₂ ) ₄ —,
CF ₃ CFHO (CF ₂ ) _6- , CF ₃ CFHO (CF ₂ CF (CF ₃ )) O (CF ₂ ) _2- ,
CF ₃ CFHO (CF ₂ CF (CF ₃ )) O (CF ₂ ) ₃ −, CF ₃ CFHO (CF ₂ CF (CF ₃ )) O (CF ₂ ) ₄ −,
CF ₃ CFHO (CF ₂ CF (CF ₃ )) O (CF ₂ ) ₆ −
From the viewpoint of the synthesis and purification of the sulfonidate, Rf ¹ and Rf ² are preferably each independently a fluorinated hydrocarbon group having 1 to 10 carbon atoms or a substituted product thereof. Preferred are each independently a fluorinated hydrocarbon group having 1 to 8 carbon atoms or a substituted product thereof, and particularly preferred are each independently a fluorinated hydrocarbon group having 1 to 6 carbon atoms or a substituted product thereof.

In the general formula (1), M is Ma, Mb _1/2 , Ma is an alkali metal other than lithium, and Mb is an alkaline earth metal. From the viewpoint of synthesis and purification of the sulfonimidate, Preferred are sodium, potassium, cesium, calcium and barium, more preferred are sodium, potassium and cesium, and particularly preferred are sodium and potassium.

Examples of the method for producing the sulfonimide salt represented by the general formula (1) include a method represented by the following reaction formula in which perfluoroalkylsulfonyl fluoride is reacted with an alkali metal salt of a trimethylsilyl group-containing perfluoroalkylsulfonamide. (For example, Inorganic Chemistry Vol. 23, pages 3720-3723 (1984) (hereinafter referred to as “Non-patent Document 2”) and Inorganic Chemistry, Vol. 32, pages 5007-5010 (1993) (hereinafter, “Non-patent Document”) Reference 3 ”)).
RfSO ₂ F + Rf′SO ₂ N (SiMe ₃ ) Na → RfSO ₂ N (Na) SO ₂ Rf ′ + Me ₃ SiF

However, the above reaction has many reaction steps including the previous stage, and in particular, an expensive compound such as hexamethyldisilazane must be used in the previous stage of the reaction, so that the sulfonimidate can be produced more efficiently. For example, the following general formula (4)
Rf ¹ SO ₂ X (4)
(Rf ¹ is the same as Rf ^{1 in the} general formula (1), and X represents a fluorine atom or a chlorine atom), and the following general formula (5)
Rf ² SO ₂ NH ₂ (5)
(Rf ² is the same as Rf ^{2 in the} general formula (1).)
And the following general formula (6)
M ₂ CO ₃ (6)
(M is the same as M in the above general formula (1).)
It can manufacture by mixing and stirring the carbonate which uses alkali metals or alkaline earth metals other than lithium represented by these in a solvent. As the reaction formula,
Rf ¹ SO ₂ X + Rf ² SO ₂ NH ₂ + M ₂ CO ₃ →
_{^{Rf 1 SO 2 N (M)}} SO 2 Rf 2 + H 2 O + CO 2 + MX
It is represented by

The carbonate represented by the above general formula (6), for _{example, Na 2 CO 3, K 2} CO 3, Cs 2 CO 3, CaCO 3, BaCO 3 and the like. The reaction solvent may be any inert solvent with respect to the reactant. Examples of the solvent used in the present invention include tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene. Ether solvents such as glycol dimethyl ether and tetraethylene glycol dimethyl ether, nitrile solvents such as acetonitrile, propionitrile, butyronitrile, malononitrile and adiponitrile, amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, HFC43 -10 mee, fluorine-containing solvents such as perfluoro-2-butyltetrahydrofuran, perfluorotributylamine, dimethyl sulfoxide, sulfolane, and the like. , Used alone or as a mixture. Of these, acetonitrile is preferred.

The reaction temperature is usually from −20 ° C. to 200 ° C., preferably from −10 ° C. to 180 ° C., more preferably from 0 ° C. to 150 ° C., particularly preferably from 10 ° C. to 100 ° C.
The reaction time is usually 0.01 hours to 48 hours, preferably 0.1 hours to 36 hours, more preferably 0.2 hours to 24 hours, particularly preferably 0.5 hours to 12 hours. .
After completion of the reaction, for example, when the sulfonimide salt represented by the general formula (1) is dissolved in the obtained reaction mixture, insoluble solids in the reaction mixture are removed by filtration, If the solvent is distilled off under reduced pressure, the sulfonimide salt represented by the general formula (1) can be obtained. The obtained sulfonimidate may be purified by a conventionally known purification method such as crystallization or column chromatography.

The inventors of the present invention directly from the sulfonimidate represented by the above general formula (1) without passing through the above-described super strong acid sulfonimidic acid, the following general formula (3)
Rf ¹ SO ₂ N (Li) SO ₂ Rf ² (3)
^(Rf 1, Rf ² is the same as ^Rf 1, Rf ² in formula (1).)
As a result of intensive studies on a method capable of producing a sulfonimide lithium salt represented by the formula (1) in a high yield, the sulfonimide acid salt represented by the general formula (1) and the inorganic lithium salt are mixed in the presence of a solvent. It was found that when the mixture was stirred, a cation of the sulfonimidate and lithium of the inorganic lithium salt occurred, and the sulfonimide lithium salt was obtained in a high yield.

Here, the following general formula (2) used in the present invention:
Li _m X (2)
The inorganic lithium salt represented by
In the general formula (2), m is 1 or 2. X is an anion selected from halide ions, hydroxide ions, carbonate ions, perchlorate ions, and sulfate ions. Specifically, examples of inorganic lithium salts containing halide ions include LiF, LiCl, LiBr, LiI, examples of inorganic lithium containing hydroxide ions, examples of inorganic lithium salts containing LiOH and carbonate ions. LiCO ₃ , LiClO ₄ as an example of an inorganic lithium salt containing a perchlorate ion, and Li ₂ SO ₄ as an example of an inorganic lithium salt containing a sulfate ion are exemplified, and a halide ion is particularly preferable as X.

  The solvent to be used may be any solvent inert to the reactants, for example, alcohol solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, butanol, tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether. , Ether solvents such as diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, nitrile solvents such as acetonitrile, propionitrile, butyronitrile, malononitrile, adiponitrile, N, N-dimethylformamide, N, N-dimethylacetamide, etc. Amide solvents, HFC43-10mee, fluorine-containing solvents such as perfluoro-2-butyltetrahydrofuran, perfluorotributylamine , Dimethyl sulfoxide, sulfolane, etc. These solvents may be used alone or in combination.

Among the above solvents, methanol, ethanol, n-propanol, isopropyl alcohol, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetonitrile, propionitrile, N, N-dimethylformamide, N, N-dimethylacetamide, and more Methanol, ethanol, isopropyl alcohol, tetrahydrofuran, ethylene glycol dimethyl ether, and acetonitrile are preferable, and methanol and acetonitrile are particularly preferable.
The amount of the sulfonimidate represented by the above general formula (1) and the inorganic lithium salt represented by the above general formula (2) is 1 mol per mol of sulfonimidate and 1 mol of the lithium lithium salt. In order to obtain a sulfonimide lithium salt in a high yield, the amount of the inorganic lithium salt used is preferably 1.01 to 10 mol per mol of the sulfonimidate. More preferably, it is 1.02 mol to 8 mol, and particularly preferably 1.05 mol to 5 mol.

The reaction temperature of the sulfonimide salt represented by the general formula (1) and the inorganic lithium salt represented by the general formula (2) is −10 ° C. to 100 ° C., preferably −5 ° C. To 90 ° C, more preferably 0 ° C to 70 ° C, and particularly preferably 10 ° C to 50 ° C.
The reaction time is 0.01 to 72 hours, preferably 0.1 to 48 hours, more preferably 0.2 to 24 hours, and particularly preferably 0.5 to 12 hours. .
After completion of the reaction, for example, when the sulfonimide lithium salt represented by the above general formula (3) is dissolved in the obtained reaction mixture, insoluble solids in the reaction mixture are removed by filtration, When the solvent is distilled off under reduced pressure, the sulfonimide lithium salt represented by the general formula (3) can be obtained.

The sulfonimide lithium salt represented by the above general formula (3) obtained above may be purified by a conventionally known purification method such as crystallization or column chromatography.
As described above, in the present invention, sulfonimide lithium salt, which is a substance useful as an electrolyte for a storage element such as a lithium ion secondary battery, can be efficiently obtained by mixing and stirring sulfonimidate and inorganic lithium salt. It provides a manufacturing technique and is extremely useful.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example.
Various physical properties were measured by the following methods.

1) Molecular structure analysis by ¹⁹ F-NMR Measuring apparatus: JNM-GSX400 type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.)
Solvent: deuterated chloroform,
Reference substance: Freon-11 (CFCl ₃ )

2) Structural analysis by MALDI-TOF / MS Measuring device: AXIMA CFR plus (manufactured by Shimadzu Corporation)
Laser: Nitrogen laser (337 nm)
Detector type: Linear mode Ion detection: Negative ion (Negative mode)
Integration count: 500 times Matrix: α-Cyano-4-hydroxycinnamic acid

3) Measurement by ion chromatograph Measuring device: IC-7000 (manufactured by Yokohama Analyticals)
Column: TSKgel SuperIC-Cation
Precolumn: TSK guard column Super IC-Cation
Eluent: 2.5 mM HNO3 + 0.5 mM histidine Standard data: Inorganic cation standard sample II (manufactured by Kanto Chemical Co., Inc.)

[Example 1]
In a 500 mL three-necked flask, CF ₃ SO ₂ NH ₂ (23.0 g, 0.154 mol), sodium carbonate (42.0 g, 0.396 mol), dehydrated acetonitrile (200 mL), HCF ₂ CF ₂ SO ₂ Cl (40 0.0 g, 0.200 mol), and the mixture was stirred at 60 ° C. for 4 hours.
When the reaction mixture was measured by ¹⁹ F-NMR, CF ₃ SO ₂ NH ₂ disappeared and it was confirmed that excess HCF ₂ CF ₂ SO ₂ Cl and HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ were formed. It was done.

The solid in the reaction mixture was removed by filtration, and the filtrate was concentrated under reduced pressure using an evaporator. The residue was further heated to 80 ° C. under reduced pressure to obtain 51.6 g of a white solid.
This solid was found to be HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ from ¹⁹ F-NMR (internal standard: C ₆ F ₆ ), MALDI-TOF / MS, and ion chromatograph ( 100% yield based on CF ₃ SO ₂ NH ₂ ).
¹⁹ F-NMR: −135.9 ppm (1F), −135.8 ppm (1F), −122.6 ppm (2F), −79.1 ppm (3F)
MALDI-TOF / MS: 312 [M-Na] ⁻
To a 200 mL three-necked flask was added HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ (9.7 g, 29 mmol), LiCl (6.2 g, 145 mmol), methanol (140 mL), and 2 at 20 ° C. Stir for hours. The solid in the reaction mixture was filtered, and the filtrate was concentrated under reduced pressure using an evaporator.

Next, acetonitrile was added to the resulting residue and stirred, and then the insoluble solid was filtered. The filtrate was concentrated under reduced pressure using an evaporator to obtain 9.0 g of a white solid. From the analysis of the ion chromatograph, sodium ions were not detected and lithium ions were detected from this solid. Further, ¹⁹ F-NMR (internal standard: C ₆ F ₆ ) and MALDI-TOF / MS showed that the obtained solid was HCF ₂ CF ₂ SO ₂ N (Li) SO ₂ CF ₃ ( Yield 97% based on HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ ).
¹⁹ F-NMR: -136.4 ppm (1F), -136.3 ppm (1F), -123.2 ppm (2F), -80.3 ppm (3F)
MALDI-TOF / MS: 312 [M-Li] ⁻

[Example 2]
Example 1 Example 1 was carried out in the same manner as in Example 1 except that (HCF ₂ CF ₂ SO ₂ ) ₂ NNa (10.6 g, 29 mmol) was used instead of HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF _3. 9.7 g of a white solid was obtained. From the analysis of the ion chromatograph, sodium ions were not detected and lithium ions were detected from this solid. Further, ¹⁹ F-NMR (internal standard: C ₆ F ₆ ) and MALDI-TOF / MS showed that the obtained solid was (HCF ₂ CF ₂ SO ₂ ) ₂ NLi ((HCF ₂ CF ₂ SO _{2) 2.} Relative to NNa, 95% yield).
¹⁹ F-NMR: -136.1 ppm (2F), -136.0 ppm (2F), -123.5 ppm (4F),
MALDI-TOF / MS: 344 [M-Li] ⁻

[Example 3]
In Example 1, instead of HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ , (CF ₃ SO ₂ ) ₂ NK (9.3 g, 29 mmol) purchased from Wako Pure Chemical Industries, Ltd. was used. Was carried out in the same manner, and 8.0 g of a white solid was obtained. From this analysis of the ion chromatograph, potassium ions were not detected and lithium ions were detected from this solid. Further, ¹⁹ F-NMR (internal standard: C ₆ F ₆ ) and MALDI-TOF / MS showed that the obtained solid was (CF ₃ SO ₂ ) ₂ NLi ((CF ₃ SO ₂ ) ₂ (Yield 96% based on NK).
¹⁹ F-NMR: -79.9 ppm (6F)
MALDI-TOF / MS: 280 [M-Li] ⁻

[Example 4]
In Example 1, instead of HCF ₂ CF ₂ SO ₂ N (Na) SO ₂ CF ₃ , (CF ₃ CF ₂ SO ₂ ) ₂ NNa (11.7 g, 29 mmol) obtained according to Non-Patent Document 3 was used. Except that, 11.0 g of white solid was obtained. From the analysis of the ion chromatograph, sodium ions were not detected and lithium ions were detected from this solid. Further, ¹⁹ F-NMR (internal standard: C ₆ F ₆ ) and MALDI-TOF / MS showed that the obtained solid was (CF ₃ CF ₂ SO ₂ ) ₂ NLi ((CF ₃ CF ₂ 94% yield based on SO ₂ ) ₂ NNa).
¹⁹ F-NMR: -118.0 ppm (4F), -79.6 ppm (6F)
MALDI-TOF / MS: 380 [M-Li] ⁻

  The sulfonimide lithium salt obtained by the production method of the present invention can be used as an electrolyte for a storage element such as a lithium ion secondary battery.

Claims (3)

The following general formula (1)
Rf ¹ SO ₂ N (M) SO ₂ Rf ² (1)
(Rf ¹ and Rf ² are each independently a fluorinated hydrocarbon group having 1 to 12 carbon atoms or a substituent thereof, M is Ma, Mb _1/2 , Ma is an alkali metal other than lithium, and Mb is Alkaline earth metal.)
A sulfonimide salt represented by the following general formula (2)
Li _m X (2)
(M is 1 or 2, and X is an anion selected from halide ions, hydroxide ions, carbonate ions, perchlorate ions, and sulfate ions.)
It is made to mix and stir with the inorganic lithium salt represented by the following general formula (3)
Rf ¹ SO ₂ N (Li) SO ₂ Rf ² (3)
^(Rf 1, Rf ² is the same as ^Rf 1, Rf ² in formula (1).)
The manufacturing method of the sulfonimide lithium salt represented by these.   The production method according to claim 1, wherein in the general formula (1), M is sodium or potassium.   The production method according to claim 1 or 2, wherein in the general formula (2), X is a halide ion.