JP2006256883A - Method for production of tetrafluoroborate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for production of an electrolyte which is easy to remove the organic solvents, moisture or the like and is suitable as a nonaqueous electrolytic solution having no discoloration or quality deterioration, and also to provide the nonaqueous electrolytic solution using the same. <P>SOLUTION: The method for production of the electrolyte, tetrafluoroborate, comprises reacting a fluoride (a) represented by general formula (1): R-F (wherein R is a 1-20C hydrocarbon group selected from the group consisting of alkyl, alkenyl, aryl, aralkyl and alkylaryl) with boron trifluoride ether complex (b) in the presence of a compressible fluid, and further reacting the resultant material with a tertiary amine and/or tertiary amidine (c). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing tetrafluoroborates. In particular, the present invention relates to a method for producing a tetrafluoroborate salt that is an electrolyte useful for a lithium battery electrolyte, an electric double layer capacitor electrolyte, or the like, which requires low moisture.

Conventionally, as a method for producing an electrolyte for a nonaqueous electrolyte, for example, when producing a quaternary ammonium BF ₄ salt, a reaction by anion exchange of a quaternary ammonium halide is generally known. For example, a method is known in which a quaternary ammonium chloride is reacted with AgBF ₄ to precipitate silver chloride to obtain a target product from a filtrate. In the case of this method, AgBF _{4 as} a raw material is extremely expensive, and it cannot be said that it can be industrially adopted. As a method of solving this problem, a method of obtaining a quaternary ammonium BF ₄ salt by reacting a quaternary ammonium carbonate with an HBF ₄ aqueous solution to remove carbon dioxide from the system (Patent Document 1), in an organic solvent A method of reacting fluoride, boron trifluoride ether complex, tertiary amidine (Patent Document 2) and the like has been proposed.
JP-A 63-284148 JP 2000-319284 A

  However, these methods for producing electrolytes have problems such as instability in quality because they cause quality deterioration such as coloring. In addition, if an adsorption treatment agent such as zeolite is used to remove moisture, crushed zeolite and unnecessary metal ions are eluted, and if an organic solvent is used, quality deterioration due to side reaction with the organic solvent, In addition, there is a problem that moisture in the organic solvent is mixed. An object of the present invention is to provide a method for producing an electrolyte that is easy to remove organic solvents, moisture, and the like and that is free from coloring and quality deterioration, and a non-aqueous electrolyte solution using the same.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the present invention comprises a reaction of a fluoride (a) represented by the following general formula (1) with a boron trifluoride ether complex (b) in the presence of a compressive fluid, and further a tertiary amine and / or a tertiary amidine. (C) is a reaction method for producing a tetrafluoroborate salt; an electrolyte for a nonaqueous electrolyte solution produced by the production method; a nonaqueous electrolyte solution comprising the electrolyte.
R-F (1)
[Wherein, R represents a hydrocarbon group having 1 to 20 carbon atoms selected from the group consisting of an alkyl group, an alkenyl group, an aryl group, an aralkyl group and an alkylaryl group. ]

  In the production method of the present invention, a fluoride (a), a boron trifluoride ether complex (b), a tertiary amine and / or a tertiary amidine (c) are reacted in a compressive fluid, and boron tetrafluoride is reacted. Since the acid salt is produced, there is no deterioration in quality such as coloring, generation of by-products due to the reaction between the solvent and water, and elution of metal ions, and an electrolyte for a non-aqueous electrolyte having a very low water content can be obtained.

In the present invention, a tertiary amine and / or tertiary amidine obtained by reacting a fluoride (a) represented by the following general formula (1) with a boron trifluoride ether complex (b) in the presence of a compressive fluid ( It is a method for producing an electrolyte for non-aqueous electrolyte, characterized in that c) is added and reacted in the presence of a compressive fluid to produce tetrafluoroborate.
R-F (1)
[Wherein, R represents a hydrocarbon group having 1 to 20 carbon atoms selected from the group consisting of an alkyl group, an alkenyl group, an aryl group, an aralkyl group and an alkylaryl group. ]

  Examples of R in the general formula (1) include C1-C20 hydrocarbon groups selected from the group consisting of alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and alkylaryl groups. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, and a sec-butyl group; Groups, propenyl groups, butenyl groups, etc .; examples of aryl groups include phenyl groups; examples of aralkyl groups include benzyl groups; examples of alkylaryl groups include 4-methyl-phenyl groups. Specific examples of (a) include methyl fluoride, ethyl fluoride, n-propyl fluoride, i-propyl fluoride, n-butyl fluoride, i-butyl fluoride, t-butyl fluoride, sec-butyl fluoride. Alkyl fluorides such as rides; Alkenyl fluorides such as propenyl fluoride; Aryl fluorides such as phenyl fluoride; Aralkyl fluorides such as benzyl fluoride; Alkyl aryl fluorides such as 4-methyl-phenyl fluoride; It is done. Among these, preferred are methyl fluoride, ethyl fluoride, n-propyl fluoride, i-propyl fluoride, n-butyl fluoride, i-butyl fluoride, t-butyl fluoride, sec-butyl fluoride. It is.

Specific examples of (b) used in the present invention include BF ₃ dialkyl having 2 to 20 carbon atoms (for example, methyl, ethyl, propyl, di-n-butyl, i-butyl, t-butyl, sec-butyl, etc.) ) Ether complexes, BF ₃ dialkenyl (eg propenyl etc.) ether complexes, BF ₃ diaryl (eg phenyl etc.) ether complexes, BF ₃ dialalkyl (eg benzyl etc.) ether complexes, BF ₃ dialkylaryl (eg 4-methylphenyl etc.) ether A complex etc. are mentioned. Among these, BF ₃ dimethyl ether complex, BF ₃ diethyl ether complex, BF ₃ di-n-propyl ether complex, i-propyl ether complex, BF ₃ di-n-butyl ether, i-butyl ether, t-butyl ether, sec-butyl ether.

Specific examples of (c) used in the present invention include the following.
Tertiary amine having one nitrogen atom: acyclic amine (C1-30, such as dimethylethylamine, diethylmethylamine, trimethylamine, triethylamine, tri-n-propylamine, i-propylamine, tri-n-butylamine , I-butylamine, t-butylamine, sec-butylamine, etc.); cyclic amine (carbon number 5-30, such as N-methylpiperidine, N-methylpyrrolidine, pyridine, etc.); aromatic amine (carbon number 9-30, eg, Tribenzylamine). Of these, preferred are trimethylamine, triethylamine, tri-n-propylamine, i-propylamine, and tri-n-butylamine.
Imidazoles: 1,2,4-trimethylimidazole, 1,2-diethyl-4-methylimidazole, 1-undecylimidazole, and preferably 1-methylimidazole, 1,2-dimethylimidazole, 1-ethylimidazole, 1,2-diethylimidazole, 1-propylimidazole, 1-butylimidazole, 1,4-dimethylimidazole, 1-phenylimidazole, 1-benzylimidazole, 1-methylbenzimidazole and the like. Of these, 1-methylimidazole, 1,2-dimethylimidazole, 1-ethylimidazole, 1,2 diethylimidazole, 1-propylimidazole, and 1-butylimidazole are more preferable.
Imidazolines: 1,2-dimethyl-4-ethylimidazoline, 1-ethyl-4-methylimidazoline, 1-undecylimidazoline, and preferably 1-methylimidazoline, 1,2-dimethylimidazoline, 1-ethylimidazoline, 1,2-diethylimidazoline, 1,2-dibutylimidazoline, 1,4-dimethylimidazoline, 1-phenylimidazoline, 1-benzylimidazoline, and the like. Of these, 1-methylimidazoline, 1,2-dimethylimidazoline, 1-ethylimidazoline, 1,2-diethylimidazoline, and 1,2-dibutylimidazoline are more preferable.
Pyrimidines: 1,2-diethyl-4,5,6-trihydropyrimidine, 1-methyl-2-benzyl-4,5,6-trihydropyrimidine, and preferably 1-methyl-4,5,6 -Trihydropyrimidine, 1-ethyl-4,5,6-trihydropyrimidine, 1,2-dimethyl-4,5,6-trihydropyrimidine, 1,5-diazabicyclo [4.3.0] nonene-5 1,8-diazabicyclo [5.4.0] undecene-7 and the like. Of these, more preferred are 1-methyl-4,5,6-trihydropyrimidine, 1-ethyl-4,5,6-trihydropyrimidine, 1,2-dimethyl-4,5,6-trihydro. Pyrimidine, 1,5-diazabicyclo [4.3.0] nonene-5, 1,8-diazabicyclo [5.4.0] undecene-7. Of the exemplified tertiary amines, imidazoles, imidazolines and pyrimidines, tertiary amidines selected from the group consisting of imidazoles, imidazolines and pyrimidines are preferred. These may be used alone or in combination.

  In the present invention, examples of the compressible fluid include carbon dioxide (31.0, 7.4), methane (-82.5, 4.6), ethane (31.1, 4.9), and propane (96). .7, 4.2), hexane (234.2, 3.0), methanol (239.4, 8.2), ethanol (240.7, 6.1), water (374.2, 22.1) Etc.) and fluids at temperatures and pressures above the critical point. In addition, the inside of a parenthesis is a critical temperature (degreeC) and a critical pressure (MPa) in order. A supercritical fluid is defined as a non-condensable fluid that exceeds the gas-liquid critical temperature and pressure inherent to the substance. The thermal motion of the molecule is intense because it exceeds the critical temperature, and the density can be continuously changed by changing the pressure from a dilute state close to the ideal gas to a high-density state corresponding to the liquid. .

The compressible fluid in the present invention is preferably used as a supercritical fluid.
Of these, carbon dioxide, methane, and ethane are preferable from the viewpoint of ease of handling, and carbon dioxide is more preferable.
The amount of the compressive fluid used in the reaction is preferably 10 to 1000 parts by weight, more preferably 30 to 800 parts by weight, particularly preferably 100 parts by weight of (a), (b) and (c). 50 to 500 parts by weight.

In the production method of the present invention, the reaction is carried out by reacting (a) and (b) (step [1]) and then (c) reacting the reactants (a) and (b). (Step [2]) is required.
Examples of the charging method (a) include continuous dripping, division, batch, and the like, and a batch loading method is preferable from the viewpoint of productivity.
Examples of the charging method of (b) and (c) include continuous dripping, division, batch, and the like, and a method of charging by continuous dripping is preferable from the viewpoint of preventing coloring.
As the process [1], for example, a predetermined amount of boron trifluoride methyl ether complex is charged into a reaction tank having a stirring device and a temperature measuring device, and can be set up to a pressure in the tank of 70 MPa and a temperature in the tank of 290 ° C., and a temperature of 50 ° C. The pressure is adjusted to 10 MPa. A predetermined amount of carbon dioxide is charged, and a predetermined amount of methyl fluoride is added dropwise with stirring while maintaining a temperature of 50 ° C. and a pressure of 10 MPa. After dropping, the reaction is performed for 8 hours.
As the step [2], for example, after the completion of the step [1], a predetermined amount of triethylamine is dropped at a reaction tank temperature of 50 ° C. After dropping, the reaction is carried out for 24 hours while maintaining a temperature of 50 ° C. and a pressure of 10 MPa to remove supercritical carbon dioxide.
Through the above steps, white crystalline methyltriethylammonium tetrafluoroborate can be obtained.

Step [1] will be described.
The temperature (° C.) during the reaction is in the supercritical region temperature range of the compressive fluid. From the viewpoint of preventing coloring, carbon dioxide is preferably 31 to 80, more preferably 32 to 70, and particularly preferably 35 to 50 ° C. It is.
The pressure (MPa) during the reaction is in the range of the supercritical region pressure of (B), and from the viewpoint of ease of handling, it is preferably 7 to 70, more preferably 8 to 50, particularly preferably 9 to 30 in the case of carbon dioxide. It is.
The reaction time (time) may be adjusted according to the reaction temperature, but is preferably 0.1 to 15, more preferably 0.3 to 12, and particularly preferably 0.5 to 10 from the viewpoint of productivity.

Next, process [2] is demonstrated.
The preferred range of temperature and pressure during the reaction is the same as in reaction (1). The reaction time (time) may be adjusted according to the reaction temperature, but is preferably 1 to 50, more preferably 2 to 40, and particularly preferably 5 to 30 from the viewpoint of productivity.

In the production method of the present invention, a known solvent (for example, described in JP-A-2002-284881, JP-A-2000-319284, etc.) can be added to the compressive fluid (B). Examples include ether solvents (dimethyl ether, diethyl ether, etc.), ketone solvents (acetone, methyl ethyl ketone, etc.), alcohol solvents (methanol, ethanol, etc.), alkane solvents (hexane, cyclohexane), and the like.
When the solvent is used, the amount used (% by weight) is preferably from 0.1 to 50, more preferably from 0.5 to 20, particularly preferably based on the weight of (a), (b) and (c). Is 1-10.

  In the production method of the present invention, the ratio of each reaction component is stoichiometrically (a) / (b) / (c) = 1/1/1 (equal ratio). Charge chemical species in excess [preferably up to 20%, especially up to 10%, for example (a) / (b) / (c) = 1.1 / 1/1], and the excess after the reaction is distilled under reduced pressure, etc. It is also possible to obtain the desired stoichiometric ratio.

The end point of the reaction can be confirmed from reaction heat or high performance liquid chromatographic analysis of the reaction solution. Moreover, the structure of the produced salt can be confirmed by NMR analysis of H and F.

The electrolyte of the present invention is obtained by reacting a fluoride (a) represented by the general formula (1) with a boron trifluoride ether complex (b) in the presence of a compressive fluid, and a tertiary amine and / or 3 It is an electrolyte composed of tetrafluoroborate obtained by reacting with a class amidine (c) in the presence of a compressive fluid.

Specific examples of the tetrafluoroborate obtained by the production method of the present invention include the following.
Quaternary ammonium salts: dimethyldiethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, i-propylammonium tetrafluoroborate, tetra-i-butylammonium tetrafluoride Borate, t-butylammonium tetrafluoroborate, sec-butylammonium tetrafluoroborate, N-methylpyridinium tetrafluoroborate, and preferably tetramethylammonium tetrafluoroborate, Methyltriethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, N, N-dimethylpiperidinium tetrafluoroborate, N, N -Dimethylpyrrolidinium tetrafluoroborate and the like. Of these, tetramethylammonium tetrafluoroborate, methyltriethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, and tetra-n-butylammonium tetrafluoroborate are more preferable. is there.

-Imidazolium salts: 1,2,3,4-tetramethylimidazolium tetrafluoroborate, 1,2-diethyl-3,4-dimethylimidazolium tetrafluoroborate, 1-undecyl-3- Methyl imidazolium tetrafluoroborate, and preferably 1,3-dimethylimidazolium tetrafluoroborate, 1,2,3-trimethylimidazolium tetrafluoroborate, 1-ethyl-3-methyl Imidazolium tetrafluoroborate, 1,2-diethyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methyl Imidazolium tetrafluoroborate, 1,3,4-trimethylimidazolium tetrafluoroborate, 1-phenyl-3-methylimidazolium tetrafluoroborate, 1-benzi 3-methylimidazolium tetrafluoroborate, 1,3-dimethyl benzimidazolium tetrafluoroborate salt. Among these, more preferred are 1,3-dimethylimidazolium tetrafluoroborate, 1,2,3-trimethylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetra Fluoroborate, 1,2-diethyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetra It is a fluorinated borate.

Imidazolinium salts: 1,2,3-trimethyl-4-ethylimidazolinium tetrafluoroborate, 1-ethyl-3,4-dimethylimidazolinium tetrafluoroborate, 1-ethyl- 2,3-dimethylimidazolinium tetrafluoroborate, 1-undecyl-3-methylimidazolinium tetrafluoroborate, and preferably 1,3-dimethylimidazolinium tetrafluoroborate, 1,2,3-trimethylimidazolinium tetrafluoroborate, 1-ethyl-3-methylimidazolinium tetrafluoroborate, 1,2-diethyl-3-methylimidazolinium tetrafluoroborate Acid salt, 1,2-dibutyl-3-methylimidazolinium tetrafluoroborate, 1,2,3,4-tetramethylimidazolinium tetrafluoroborate, 1-phenyl-3-methylimid Zoriniumu tetrafluoroborate, 1-benzyl-3-methyl imidazolium tetrafluoroborate salt. Among these, more preferred are 1,3-dimethylimidazolinium tetrafluoroborate, 1,2,3-trimethylimidazolinium tetrafluoroborate, 1-ethyl-3-methylimidazole. Linium tetrafluoroborate, 1,2-diethyl-3-methylimidazolinium tetrafluoroborate, 1,2-dibutyl-3-methylimidazolinium tetrafluoroborate, 1,2 3,4-tetramethylimidazolinium tetrafluoroborate.

Pyrimidine derivative salts: 1,2,3-triethyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1,3-dimethyl-2-benzyl-4,5,6-trihydropyri Midinium tetrafluoroborate, and preferably 1,3-dimethyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1,3-diethyl-4,5,6-trihydro Pyrimidinium tetrafluoroborate, 1-ethyl-3-methyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1,2,3-trimethyl-4,5,6- Trihydropyrimidinium tetrafluoroborate, 1,2,3-triethyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1-methyl-1,5-diazabicyclo [4. 3.0] Nonene-5 tetrafluoroborate, 1-methyl 1,8-diazabicyclo [5.4.0] undecene-7 tetrafluoroborate salt. Of these, more preferred are 1,3-dimethyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1-ethyl-3-methyl-4,5,6-trihydropyrimidi. Nium tetrafluoroborate, 1,2,3-trimethyl-4,5,6-trihydropyrimidinium tetrafluoroborate, 1-methyl-1,5-diazabicyclo [4.3.0] Nonene-5 tetrafluoroborate, 1-methyl-1,8-diazabicyclo [5.4.0] undecene-7 tetrafluoroborate.
Among these tetrafluoroborates, imidazolium salts and pyrimidine derivative salts are preferable from the viewpoint of the performance of the electrolytic solution, more preferably imidazolium salts, and particularly preferably 1-ethyl-3-methylimidazolium salt. .

  The water content of the electrolyte obtained by the production method of the present invention is preferably 500 ppm or less, more preferably 300 ppm or less, particularly preferably 100 ppm or less from the viewpoint of electrochemical stability (moisture measurement method: Karl Fischer moisture measurement method [ Coulometric titration method, detection limit 1 ppm, conforming to JIS: K2275]).

The non-aqueous electrolyte solution of the present invention is obtained by reacting a fluoride (a) represented by the general formula (1) with a boron trifluoride ether complex (b) in the presence of a compressive fluid, a tertiary amine and It is a nonaqueous electrolyte solution comprising an electrolyte comprising a tetrafluoroborate salt and a solvent obtained by reacting with tertiary amidine (c) in the presence of a compressive fluid.

The following are mentioned as a specific example of the organic solvent used when using the electrolyte obtained by the manufacturing method of this invention as a non-aqueous electrolyte. Two or more of these can be used in combination.
Ethers: chain ethers (eg, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether); cyclic ethers (eg, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, etc.).
Amides: N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylpropionamide, hexamethylphosphorylamide, N-methylpyrrolidone and the like.
Lactones: γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, δ-valerolactone, and the like.
Nitriles: acetonitrile, acrylonitrile, etc.
Carbonates: cyclic carbonates (for example, ethylene carbonate, propylene carbonate, butylene carbonate, etc.), chain carbonates (for example, dimethyl carbonate, diethyl carbonate, etc.).
Sulfoxides: chain sulfoxide (for example, dimethyl sulfoxide), cyclic sulfoxide (for example, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane) and the like.
Other organic solvents: heterocyclic solvents (N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, etc.).

  The solvent is preferably an ether, lactone, carbonate, or sulfoxide from the viewpoint of electrochemical stability and electrolyte solubility, and particularly preferably ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl. Examples thereof include carbonates such as carbonate and diethyl carbonate, or sulfoxides such as dimethyl sulfoxide (DMSO), sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane. The water content of the solvent used is required to be low as in the above electrolyte, and is usually 100 ppm or less, preferably 10 ppm or less to 50 ppm.

  The concentration when the electrolyte obtained by the production method of the present invention is dissolved in the organic solvent and used as a non-aqueous electrolyte is preferably 5 from the viewpoint of electrical conductivity and solubility, based on the entire weight of the electrolyte. -40% by weight, particularly preferably 10-30% by weight. Moreover, when the electrolyte obtained by the production method of the present invention is dissolved in the organic solvent and used as a non-aqueous electrolyte, the water content is preferably 200 ppm or less, more preferably 50 ppm or less, and particularly preferably 30 ppm or less ( Moisture measurement method: the same Karl Fischer moisture measurement method as electrolyte moisture measurement).

[Example]
EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples without departing from the gist of the present invention. Unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”.
<Moisture measurement method>
In accordance with JIS K2275, 0.1 g of a sample was used and measured by Karl Fischer moisture measurement method (coulometric titration method).
<Chlorine content>
Based on JISK8001, it measured by a turbidimetric method.
<Sodium ion determination method>
1 g of a sample was taken, 1 ml of hydrochloric acid (35 wt%) was added, and water was added to a total volume of 100 ml and dissolved. The measurement was performed at a wavelength of 589 nm using an atomic absorption flame light shared spectroscopic analyzer AA-860 manufactured by Nippon Jarrell-Ash Co., Ltd.
<NMR measurement>
A 5 mg sample was dissolved in 0.2 ml deuterated DMSO, and 1H-NMR was measured at 270 MHz.
<Example 1>
A reactor equipped with a stirrer, circulation tank, and temperature sensor, and charged with 114 parts of boron trifluoride methyl ether complex in a reaction tank that can be set up to a pressure of 70 MPa and a temperature of 290 ° C, adjusted to a temperature of 50 ° C and a pressure of 10 MPa. did. 50 parts of carbon dioxide was charged, and 34 parts of methyl fluoride was added dropwise over 1 hour with stirring at a temperature of 50 ° C. and a pressure of 10 MPa. Reaction was performed for 8 hours after dripping. Next, 101 parts of triethylamine was added dropwise over 1 hour, and the mixture was allowed to react for 24 hours while stirring at a temperature of 50 ° C. and a pressure of 10 MPa. NMR measurement was performed, and it was confirmed that the reaction rate was 99% or more from the signal of the raw material triethylamine and the signal of methyltriethylammonium tetrafluoroborate, and the reaction was completed.
After completion of the reaction, carbon dioxide was removed to obtain white methyltriethylammonium tetrafluoroborate (electrolyte 1) having a water content of 100 ppm.

<Example 2>
A water content of 100 ppm and white 1-ethyl-2,3-dimethylimidazolinium tetrafluoroborate in the same manner as in Example 1 except that 112 parts of 1-ethyl-2-methylimidazoline was used instead of 101 parts of triethylamine. (Electrolyte 2) was obtained.

<Example 3>
Similar to Example 1 except that 39 parts of ethyl fluoride were used instead of 34 parts of methyl fluoride, and 66 parts of 1-methylimidazole was used instead of 101 parts of triethylamine. -Methylimidazolium tetrafluoroborate (electrolyte 3) was obtained.

<Example 4>
A white methyltriethylammonium tetrafluoroborate (electrolyte 4) was obtained in the same manner as in Example 1 except that the reaction pressure was changed from 10 MPa to 25 MPa.

<Example 5>
A white methyltriethylammonium tetrafluoroborate (electrolyte 5) was obtained in the same manner as in Example 1 except that the reaction pressure was changed from 10 MPa to 50 MPa.

<Example 6>
A white methyltriethylammonium tetrafluoroborate (electrolyte 6) was obtained in the same manner as in Example 1 except that the reaction temperature was changed from 50 ° C to 35 ° C.

<Example 7>
A white methyltriethylammonium tetrafluoroborate (electrolyte 7) was obtained in the same manner as in Example 1 except that the reaction temperature was changed from 50 ° C to 70 ° C.

<Example 8>
1,11 parts of the electrolyte and 89 parts of propylene carbonate having a water content of 30 ppm were mixed to obtain a uniform, transparent and colorless electrolytic solution (1). It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 9>
An electrolyte solution (2) was obtained in the same manner as in Example 9 except that the electrolyte 1 was changed to the electrolyte 2. It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 10>
An electrolytic solution (3) was obtained in the same manner as in Example 9 except that the electrolyte 1 was changed to the electrolyte 3. It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 11>
Except changing the electrolyte 1 to the electrolyte 4, it carried out similarly to Example 9, and obtained the electrolyte solution (4). It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 12>
An electrolyte solution (5) was obtained in the same manner as in Example 9 except that the electrolyte 1 was changed to the electrolyte 5. It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 13>
Except changing the electrolyte 1 to the electrolyte 6, it carried out similarly to Example 9, and obtained the electrolyte solution (6). It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Example 14>
An electrolyte solution (7) was obtained in the same manner as in Example 9 except that the electrolyte 1 was changed to the electrolyte 7. It was 40 ppm as a result of measuring the water | moisture content of electrolyte solution.

<Comparative Example 1>
209 parts of borohydrofluoric acid (concentration: 42% by weight) are charged in an autoclave reaction vessel, and then 382 parts of a methanol solution of methyltriethylammonium methyl carbonate (concentration: 50% by weight) are added dropwise over about 30 minutes. The reaction was performed while generating gas. After the generation of carbon dioxide gas was stopped, the solvent and the like were removed at a temperature of 100 to 130? Under reduced pressure for about 3 hours. When the distillation stopped, the inside of the reaction vessel was a viscous liquid, and when cooled, yellow-brown methyltriethylammonium tetrafluoroborate was obtained (electrolyte 8). As a result of measuring the water | moisture content of solid, it was 3000 ppm with respect to the crystal | crystallization.

<Comparative example 2>
An autoclave reaction vessel was charged with 709.5 aqueous silver borofluoride solution (concentration: 40% by weight), and then 303 parts of a methanol solution of methyltriethylammonium chloride (concentration 50% by weight) was added dropwise over about 30 minutes with stirring. A white precipitate formed with the addition. After the precipitate was filtered off, the solvent and the like were removed from the solution at a temperature of 100 to 130 ° C. under reduced pressure for about 3 hours. When the distillation stopped, the inside of the reaction vessel was a viscous liquid, and when cooled, tan methyltriethylammonium tetrafluoroborate was obtained (electrolyte 9). As a result of measuring the water | moisture content of a solid, it was 3000 ppm with respect to a crystal | crystallization, and as a result of measuring a chlorine content by a turbidimetric method, it was 30 ppm with respect to a crystal | crystallization.

<Comparative Example 3>
11 parts of the electrolyte obtained in Comparative Example 1 and 89 parts of propylene carbonate having a water content of 30 ppm were mixed to obtain a uniform and light brown transparent electrolytic solution (8).

<Comparative example 4>
20 parts of zeolite (3A type, pellet form) was mixed with the electrolytic solution (8) and allowed to stand for 24 hours. A part of the zeolite was crushed and a fine powder was present in the liquid. This was filtered off to obtain an electrolytic solution (9). As a result of measuring the water content, the water content was 250 ppm. In addition, 10 ppm of sodium ion, which seems to be attributed to zeolite, was detected.
Table 1 shows the water contents of the electrolytes (1) to (9) of Examples 1 to 7 and Comparative Examples 1 and 2.

<Safety test>
Using the electrolytic solutions (1) to (9), 10 electric double layer capacitors were respectively prepared, and using the obtained capacitors, load and discharge were repeated at 70 ° C. and 2.5 V, and a high temperature load test was performed. The time was run and the presence or absence of liquid leakage was observed. Table 2 shows the number of capacitors in which liquid leakage occurred.

From the above results, it can be seen that the electrolyte obtained by the production method of the present invention has a very low water content and high purity as compared with the comparative example.
Moreover, since the electrolyte solution of this invention is high purity, it turns out that the stability of a capacitor | condenser is high compared with a comparative example.

The electrolyte and electrolyte obtained by the present invention are extremely low in moisture and high in purity, and thus are useful for lithium batteries and electric double layer capacitors.

Claims (7)

In a compressive fluid, a fluoride (a) represented by the following general formula (1) is reacted with a boron trifluoride ether complex (b), and a tertiary amine and / or a tertiary amidine (c) is further reacted. A method for producing a tetrafluoroborate salt, characterized by being additionally reacted.
R-F (1)
[Wherein, R represents a hydrocarbon group having 1 to 20 carbon atoms selected from the group consisting of an alkyl group, an alkenyl group, an aryl group, an aralkyl group and an alkylaryl group. ]   The method for producing an electrolyte according to claim 1, wherein (c) is at least one tertiary amidine selected from the group consisting of imidazoles, imidazolines and pyrimidines.   The manufacturing method according to claim 1, wherein the compressive fluid is carbon dioxide in a supercritical state.   The production method according to any one of claims 1 to 3, wherein the pressure during the reaction is 7 to 70 MPa, and the temperature is 31 to 80 ° C.   An electrolyte for a nonaqueous electrolytic solution comprising a tetrafluoroborate salt produced by the production method according to claim 1.   6. The electrolyte for non-aqueous electrolyte according to claim 5, wherein the water content is 500 ppm or less. A nonaqueous electrolytic solution obtained by dissolving the electrolyte according to claim 5 or 6 in at least one solvent selected from the group consisting of cyclic carbonate, chain carbonate, cyclic sulfoxide and cyclic ether.