WO2006090657A1

WO2006090657A1 - Process for producing boron tetrafluoride, boron tetrafluoride produced by said process, electrolysis solution for electric double layer capacitor using said boron tetrafluoride, and process for producing said electrolysis solution

Info

Publication number: WO2006090657A1
Application number: PCT/JP2006/302933
Authority: WO
Inventors: Yutaka Kanbara; Kenji Morohashi
Original assignee: Mitsubishi Gas Chemical Company, Inc.
Priority date: 2005-02-23
Filing date: 2006-02-20
Publication date: 2006-08-31
Also published as: JP5029353B2; JPWO2006090657A1

Abstract

This invention provides a process for producing boron tetrafluoride represented by Q+BF4-. The production process is characterized by comprising reacting (A) a salt compound represented by Q+X- wherein Q+ represents an onium ion or a metal ion, X- represents an inorganic acid ion except for BF4-, an organic acid ion, or a hydroxide ion, (B) at least one boron compound selected from the group consisting of orthoboric acid, metaboric acid, tetraboric acid, boron oxide, and a boric ester represented by B(OR1)(OR2)(OR3) wherein R1 represents an alkyl group having 1 to 10 carbon atoms and R2 and R3 represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, provided that R1, R2, and R3 may be the same or different, and (C) hydrogen fluoride. There are also provided a boron tetrafluoride produced by the above process, an electrolysis solution for an electric double layer capacitor using said boron tetrafluoride, and a process for producing the electrolysis solution. The production process can produce high-purity boron tetrafluoride for use in an electrolysis solution for an electric double layer capacitor without using an expensive and highly toxic BF3 gas in an industrially advantageous manner. In particular, boron tetrafluoride having good properties as a nonaqueous electrolysis solution for an electric double layer capacitor can be produced in an industrially very advantageous manner, and, thus, a high-performance nonaqueous electrolysis solution for an electric double layer capacitor can be produced in a cost-effective manner.

Description

Specification

Method for producing boron tetrafluoride salt, boron tetrafluoride salt obtained by the method, electrolytic solution for electric double layer capacitor and method for producing the same

Technical field

The present invention relates to a method for producing boron tetrafluoride salt (hereinafter sometimes referred to as BF salt),

Four

BF salt obtained by the method, electrolyte solution for electric double layer capacitor using the BF salt, and

4 4

It relates to the manufacturing method. Electric double layer capacitors are attracting attention as power storage systems that have excellent characteristics, such as high-speed charging / discharging, cycle characteristics, and low environmental load.

Background art

[0002] An electrolytic solution for an electric double layer capacitor is usually composed of an electrolyte salt and a solvent.

When water is used as the solvent, the withstand voltage is limited to the electrolysis voltage of water, but when a non-aqueous solvent is used, it can be used at a voltage higher than that of water, and the electric power stored in the electric double layer capacitor Due to the large amount, non-aqueous electrolytes are mainly used for large electric double layer capacitors with large storage capacity. Electric double layer capacitors that use non-aqueous electrolytes are required to have particularly high purity because trace amounts of moisture and impurities such as halogens affect the characteristics.

As non-aqueous electrolyte, Onium BF salt is changed to propylene carbonate (PC).

Four

Dissolved products are mainly used.

[0003] As a method for producing such a BF salt, for example, Patent Document 1 discloses an organic salt (quaternary).

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A method for producing a corresponding inorganic acid salt by carrying out anion exchange between an ammonium salt and an inorganic acid is described, and a BF salt can be produced by using an aqueous borofluoric acid solution as the inorganic acid. However, this method is relatively expensive.

Four

The raw material is hydrofluoric acid. In addition, in order to handle borohydrofluoric acid, which is a super strong acid, it is necessary to configure the apparatus with a high-priced, corrosion-resistant material. Furthermore, since borohydrofluoric acid is usually marketed as an aqueous solution of about 50% and becomes a reaction in water, in order to recrystallize and purify BF salt with high solubility in water, it is heated and concentrated to a solvent with low solubility. Etc. Is necessary. At this time, borohydrofluoric acid and BF salt are decomposed in an aqueous solution.

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(Patent Document 2), and when concentrated by heating,

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There is a problem.

[0004] In addition, as described above, water in the non-aqueous electrolyte for an electric double layer capacitor adversely affects the characteristics of the electric double layer capacitor, so water must be reduced to the limit. For this reason, it is preferable that the electrolyte can be produced in a non-aqueous system without using water since the burden of the electrolyte purification process is reduced. For this purpose, a non-aqueous reaction method is also known. In Patent Document 3, BF and hydrogen fluoride are blown into a non-aqueous solvent to react with an onium salt.

Three

And non-aqueous BF salt is obtained. This method is superior in the absence of water

Four

Use BF. In addition, BF is expensive to withstand high pressures that are highly toxic with gases at room temperature.

3 3

Equipment and safety equipment are necessary. In addition, because of the high reactivity of BF,

Three

There is concern about the reaction.

[0005] On the other hand, a method for producing an alkylammonium salt, which is one of the onium salts of BF salt

Four

For example, a method is known in which an alkynoleamine and an organic acid ester such as dialkyl carbonate or formic acid ester or hydroxycarboxylic acid ester are subjected to a quaternization reaction to obtain an alkyl ammonium alkyl carbonate or organic acid salt (Patent Literature). 1, Patent Document 3 and Patent Document 4). The latter method using an organic acid ester is a method for reacting an alkylamine and an alkyl halide, which is a general method for producing an alkyl ammonium salt. It is an excellent method with no contamination.

[0006] Further, as described in Patent Document 1 and Patent Document 4, when an alkyl ammonium alkyl carbonate produced by the reaction of dialkyl carbonate and amine is used,

4 At the same time, carbon dioxide and alcohol are by-produced, and dialkyl carbonate cannot be recovered. On the other hand, as described in Patent Document 3, the quaternization of alkylamine and hydroxycarboxylic acid ester proceeds well, and the resulting alkylammonium hydroxycarboxylate power, in the synthesis of BF salts thereof. , Hydroxycarboxylic acid by-produced simultaneously with BF salt is stable in the system

4 4

It can be recycled to the quaternization process by esterifying it. However, when producing a BF salt by the method described in these patent documents,

Four

As mentioned above, although it can be manufactured non-aqueous, it uses expensive and highly toxic BF,

Three

Expensive equipment and safety equipment that can withstand high pressure are required.

[0007] The conventional BF salt production method using borohydrofluoric acid as described above is expensive and super strong acid.

Four

In addition to handling borohydrofluoric acid aqueous solution, high purity Onium BF salt

4 There are problems that it is difficult to obtain and cannot be made non-aqueous. In addition, conventional methods for producing non-aqueous BF salts

Four

The method has problems such as using expensive and highly toxic BF gas as a raw material. In addition, the conventional BF

3 4 There is a problem that the electrolytic solution for an electric double layer capacitor using a salt as an electrolyte is expensive. Patent Document 1: Japanese Patent Publication No. 7-116113

Patent Document 2: JP 2000-315630 A

Patent Document 3: Japanese Patent Laid-Open No. 2003-96031

Patent Document 4: Japanese Patent Laid-Open No. 2003-212828

Disclosure of the invention

[0008] The object of the present invention has been made in view of the above-mentioned problems in the prior art, and a high-purity BF salt used in an electrolytic solution for an electric double layer capacitor is expensive and highly toxic.

Four

Le, BF gas is not used, and it is industrially advantageous to produce an electrolytic solution for electric double layer capacitors

Three

Is to provide an economically advantageous method.

[0009] As a result of intensive studies to achieve the above object, the present inventors have made an expensive and toxic reaction by reacting an onium salt compound or a metal salt compound with a specific boron compound and hydrogen fluoride. BF salt can be obtained industrially without using high BF gas.

3 4

BF salt obtained by this method is a good non-aqueous electrolyte for electric double layer capacitors

Four

BF salt can be produced in a non-aqueous system that does not by-produce water in the system by using a borate ester compound as a boron source.

Four

In addition, when an alkyl ammonium organic acid salt obtained by the reaction of an alkylamine and an organic acid ester is used as a raw material as an onium salt, a BF salt can be produced very advantageously in the manufacturing process. The present invention has been reached.

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That is, the present invention provides the following BF salt production method, BF salt and electric double layer capacitor

4 4

An electrolytic solution and a manufacturing method thereof are provided. [0010] 1. (A) —a salt compound represented by the general formula (1),

Q + X— (1)

(In the formula, Q ⁺ represents an ion or metal ion, X— represents an inorganic acid ion excluding BF—,

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(Represents organic acid ion or hydroxide ion)

(B) one or more boron compounds selected from the group consisting of orthoboric acid, metaboric acid, tetraboric acid, boron oxide and a boric acid ester represented by the general formula (2), and

B (OR ¹ ) (OR ² ) (OR ³ ) (2)

(Wherein R ¹ represents an alkyl group having from 10 to 10 carbon atoms, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ¹ , R ² and R ³ are the same or different. May be)

(C) A process for producing a boron tetrafluoride salt represented by the general formula (3), characterized by reacting hydrogen fluoride.

Q + BF― (3)

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(In the formula, Q ⁺ is the same as in general formula (1).)

[0011] 2. —In the general formulas (1) and (3), Q ⁺ is one or more ions selected from the group consisting of lithium ions, alkylammonium ions, alkylphosphonium ions, and imidazolium ions. The method for producing boron tetrafluoride salt according to 1 above.

3. The process for producing a boron tetrafluoride salt according to 2 above, wherein, in the general formulas (1) and (3), Q ⁺ is a tetraethylammonium ion, a trimethylammonium ion or a jetyldimethylammonium ion.

4. The process for producing a boron tetrafluoride salt according to 2 above, wherein in formulas (1) and (3), Q ⁺ is an imidazolium ion.

5. The method for producing a boron tetrafluoride salt according to any one of 1 to 4 above, wherein in the general formula (1), X— is an organic acid ion.

[0012] 6. (A) Component strength S, The method for producing a boron tetrafluoride salt according to any one of the above 1 to 4, which is obtained by reacting an alkylamine with an organic acid ester or dialkyl carbonate.

7. The method for producing a boron tetrafluoride salt according to 6 above, wherein the component (A) is obtained by reacting an alkylamine with a hydroxycarboxylic acid ester.

8. (A) component, (B) component and (C) component are reacted in the presence of a non-aqueous solvent. No. 7 or any method for producing a boron tetrafluoride salt.

9. The method for producing a boron tetrafluoride salt according to 8 above, wherein the boric acid ester represented by the general formula (2) is used as the component (B).

10. Using the borate ester represented by the general formula (2) as a solvent, reacting the components (A), (B) and (C) A method for producing a boron salt.

[0013] 11. A boron tetrafluoride salt produced by any one of the methods 1 to 10 above.

12. A nonaqueous electrolytic solution for an electric double layer capacitor comprising the boron tetrafluoride salt described in 11 above.

13. A method for producing a nonaqueous electrolytic solution for an electric double layer capacitor, wherein the boron tetrafluoride salt of 11 is dissolved in a nonaqueous solvent. BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, the present invention will be described in detail. First, the method for producing a boron tetrafluoride salt of the present invention comprises a salt compound represented by the general formula (1) of the component (A), a boron compound of the component (B) and hydrogen fluoride of the component (C). It is characterized by producing a boron tetrafluoride salt represented by the general formula (3) by reaction.

Q + X— (1)

(In the formula, Q ⁺ represents an ion ion or a metal ion, and X— represents an inorganic acid ion, an organic acid ion or a hydroxide ion excluding BF—)

Q + BF― (3)

(In the formula, Q ⁺ is the same as in general formula (1).)

[0015] Q ^{+ in the} general formulas (1) and (3) represents an onion ion or a metal ion.

Examples of ion ions include ammonium ion, phosphonium ion, sulfoyuumion, oxonium ion, arsonium ion, selenonium ion, stibonium ion, stanoyuum ion, odonium ion, diazonium ion, Examples include imidazolium ion and nitronium ion. Examples of the bonding group bonded to the central element of these onium salt compounds include hydrogen, an aliphatic group, an aromatic group, and an alkyl group including an alicyclic group. The alkyl group includes nitrile, amide, ether, ester. With a substituent such as alcohol, halogen, etc. It may be replaced. Further, a plurality of linking groups may be different or the same, or these may be bonded to form a ring, or a nitrogen atom or an amidine ring having an unsaturated bond may be formed. In addition, two or more kinds of onion ions may be bonded even if two or more kinds of onion ions are bonded.

[0016] The metal ions are not particularly limited, but alkali metal ions such as lithium ions, sodium ions and potassium ions, alkaline earth metal ions such as magnesium ions and calcium ions, zinc ions, silver ions and copper ions. Metal cations that bind to BF, such as nickel ions and force-donium ions. Among these metal ions, lithium ion is particularly useful as an electrolytic solution for electric double layer capacitors.

[0017] Among these ion ions, those particularly useful as an electrolytic solution for electric double layer capacitors include alkyl ammonium ions, alkyl phosphonium ions, and imidazolium ions.

The above-mentioned alkyl ammonium ions and alkyl phosphonium ions are those in which alkyl is symmetrically arranged on the nitrogen atom or phosphorus atom, in which alkyl is asymmetrically arranged, in which alkyl is arranged in a ring, or partial force of alkyl. Even those substituted with a nitrile group, an ether group, an alcohol group, an ester group or a halogen group are acceptable.

Compounds having an imidazolium ion include amidine compounds such as 1,3-dimethylimidazolium, 1-methinoleol 3-ethenoreyl imidazolium, 1,2,3-trimethinoremitita, and imidazolium salts. Etc.

In the present invention, tetraethylammonium, trimethylethylammonium or jetyldimethylammonium, which is an alkylammonium ion, and an imidazolium ion are particularly preferably used.

[0018] Specific examples of the compound having an alkylammonium ion and an alkylphosphonium ion include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetraptylammonium, tetrapentylammonium, tetrahetero Symmetric alkyl ammonium salts such as xynormonium, tetraisopropylammonium, tetratertiary butylammonium; triethylmethylammonium, jetyldimethylammonium, trimethylethylammonium, trimethylpropylammonium, trimme Butylbutylammonium, trimethylpentylammonium, trimethylhexylammonium, heptylammonium, dimethyldihexylammonium, dimethylethylpropylammonium, dimethylethylbutylbutylammonium, dimethylethylheptylammonium, dimethylethyl Hexyl ammonium, dimethyl propyl butyl ammonium, dimethyl propyl heptyl ammonium, dimethyl propyl hexyl ammonium, dimethyl butyl propyl ammonium, dimethyl butyl heptyl ammonium, dimethylolene butyl hexyl ammonium Asymmetric alkylammonium salts such as dimethyl, triphenylmethylammonium; dimethylpiperidinium, jetylbiperidinium, dipropylpiperidinium, dibutylpiperidinium, Pentylpiperidinium, dihexylpiperidinium, methylethylpiperidinium, methylpropylpiperidinium, methylbutylpiperidinium, methylpentylpiperidinium, methylhexylpiperidinium, methylhexylpiperidinium, Ethylpropylpiperidinium, Ethylbutylpiperidinium, Ethylpentylpiperidinium, Ethylhexylpiperidinium, Propylbutylpiperidinium, Propylpentylpiperidinium, Propylhexylpiperidinium , Dimethylpyrrolidinium, jetyl lysinium, dipropylpyrrolidinium, dibutylpyrrolidinium, dipentylpyrrolidinium, dihexylpyrrolidinium, methylethylpyrrolidinium, methylpropylpyrroline Dinium, methylbutylpyrrolidinium, methylpentylpi Lydinium, methylhexylpyrrolidinium, ethylpropylpyrrolidinium, ethylbutylpyrrolidinium, ethylpentylpyrrolidinium, ethylhexylpyrrolidinium, propylbutylpyrrolidinium, propylpentylpyrrole Dinium, Propylhexylpyrrolidinium, 1,4-Tetramethylenepyrrolidinium, 1,5_Pentamethylenepyrrolidinium, 1,6_Hexamethylenepirine Lidinium, 1,4-Tetramethylenepiperidinium Cyclic ammonium salts such as 1,5_pentamethylenepiperidinium and 1,6_hexamethylenepiberidinium; nitrile groups such as trimethylcyanomethyl and methylethylpropylcyanoethylammonium Ethers such as substituted ammonium and methylethylpropylmethoxyethyl ammonium Anne Alcohol substituted ammonium such as monium, ester, trimethylhydroxyethyl ammonium, triethyl hydroxyethyl ammonium, ethylmethylpropyl hydroxyammonium, trimethyl 2-chloroethyl ammonium, triethyl 2-chloroethyl ammonium And halogen-substituted ammonium salts such as phosphonium salts whose central element is P.

[0019] In the general formula (1) of the component (A), if X— is an anion excluding BF—, the reaction is good.

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It progresses and can obtain the BF salt represented by the general formula (3).

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Specific examples of X— include inorganic acid ions and hydroxide ions, halogen ions such as fluorine, chlorine, bromine and iodine, CIO—, CIO—, NO—, SO ² —, HCO—, CO ² —, PO ³ —, H

4 3 3 4 3 3 4

PO ² —, H PO—, Shea isothiocyanate, etc. Also as organic acid ions

4 2 4

, Carbonate ions such as formate ion, acetate ion, propionate ion, isobutyrate ion, oxalate ion, acrylate ion, methacrylate ion, lactate ion, 2-hydroxyisobutyrate ion, and monomethyl carbonate ion ( CH CO-), monoethyl acetate (CHC)

3 3 2 5

O-), monopropyl carbonate (C H CO-), monobutyl carbonate (C H CO-), etc.

3 3 7 3 4 9 3 monoalkyl carbonate ions. Of these, organic acid ions are preferred in view of the ease of purification after the reaction and the effects of residual residues.

[0020] When an electrolyte for an electric double layer capacitor is industrially produced in large quantities, an alkyl ammonium organic acid salt may be used in the salt compound represented by the general formula (1). preferable. In addition, alkylammonium organic acid salt can be produced by using a quaternization reaction between alkylamine and organic acid ester S, and BF with high purity can be easily obtained.

Four

Industrially superior as a process.

[0021] In such a quaternization reaction, an organic acid ester or a dialkyl carbonate is used. Examples of organic acid esters include methyl formate, methyl acetate, methyl propionate, methyl isobutyrate, dimethyl oxalate, methyl acrylate, methyl methacrylate, methyl lactate, methyl 2-hydroxyisobutyrate, and the like. Examples thereof include carboxylic acid esters in which the group is changed to an ethyl group, a propyl group, a butyl group, or the like. On the other hand, examples of the dialkyl carbonate include dimethyl carbonate, jetyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl ethyl carbonate and the like. Among these, dimethyl carbonate and methyl 2-hydroxyisobutyrate are preferable from the viewpoint of reaction rate, availability of raw materials, and stability. Methyl 2-hydroxyisobutyrate is produced in large quantities as an intermediate for the production of methyl methacrylate, called the new ACH (aceton cyanohydrin) method, and is not decomposed during the production of BF salts. Since it can be reused in the recycle reaction, it is particularly preferably used.

[0022] Examples of the alkylamine in this quaternization reaction include symmetric trialkylamines such as trimethylamine, triethylamine, tripropynoleamine, and tributylamine, dimethylethanolamine, dimethylpropylamine, dimethylbutylamine, Jetylmethylamine, Jetylpropylamine, Jetylbutylamine, Dipropylmethylamine, Dipropylethanolamine, Dipropylbutylamine, Dibutylmethylamine, Dibutylethylamine, Dibutylpropylamine, Examples include asymmetric amines such as methylethylpropylamine, methylethylbutylamine, methylbutylpropylamine, and ethylpropylbutylamine. Among them, symmetric trialkylamines with the same three alkyl groups are produced in large quantities. Is available at a low price , Especially Toryechiruamin is preferable.

[0023] As described in Patent Document 4, the quaternization reaction proceeds well even with the primary amine amine or secondary amine amine force. For this reason, primary amines or secondary amines can be used as alkylamines by the quaternization reaction of alkylamines with organic acid esters. Secondary amines such as dipropylamine, dibutylamine, methylethylamine, methylpropylamine, methylbutylamine, ethylpropylamine, ethylbutylamine, propylbutylamine and the like can be mentioned. Of these, amines having a single alkyl group, particularly ethylamine and jetylamine, which are produced in large quantities on an industrial scale are preferred.

[0024] The reaction conditions for the quaternization reaction are usually carried out by charging an alkylamine and an organic acid ester into a reaction vessel and heating. The amount of the organic acid ester used is usually from 0.01 to 100 monoles, preferably from 0.1 to 10 monoles per alkylamine 1 monole.

In the case of batch operation with the raw material charging method at this time, all the raw materials can be charged all at once.

The reaction temperature varies depending on the type and composition of raw materials used, reaction time, etc. It is in the range of 300 ° C, preferably in the range of 80-200 ° C. When the reaction temperature is lower than 50 ° C, the reaction is not completed, and when it is higher than 300 ° C, there is a concern about decomposition. The reaction pressure is not particularly limited, but it can be suitably carried out at a self-pressure (usually about 0 to 5 MPa (gauge pressure)) at the reaction temperature of the reaction solution. The reaction time varies depending on the type and composition of the raw materials used, the reaction temperature, etc., and cannot be generally stated, but is usually in the range of 0.5 to 50 hours.

Although the quaternization reaction proceeds favorably without a solvent, the reaction can also be carried out using an arbitrary solvent including a polar solvent such as alcohol or an additive such as carboxylic acid. If necessary, it can be carried out in an atmosphere that does not affect the reaction of nitrogen, argon, helium, etc. The alkylammonium organic acid salt produced in the quaternization reaction is distilled by a conventional method, for example, distilling a low-boiling fraction. If necessary, it can be easily separated and recovered from the reaction product solution by recrystallization. In addition, alkylammonium organic acid salts are not separated and recovered, and used as they are for the production of BF salts.

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It can also be used. Further, the quaternization reaction can be carried out by either a batch method or a distribution method. The boron compound (B) in the production of the BF salt of the present invention includes orthoboric acid (H B

4 3

O), metaboric acid (HBO), tetraboric acid (H B0), boron oxide (B 2 O) and general formula (2)

3 2 2 4 7 2 3

A borate ester represented by

B (OR ¹ ) (OR ² ) (OR ³ ) (2)

(Wherein R ¹ represents an alkyl group having from 10 to 10 carbon atoms, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ¹ , R ² and R ³ are the same or different. The boric acid ester represented by the general formula (2) is trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, tripentyl borate, trihexyl borate, trito borate Butyl, trioctyl borate, trinonyl borate, tridecyl borate, triisobutyl borate, tri-tert-butyl borate, triallyl borate, tricyclohexyl borate, triphenyl borate, ethyl dimethyl borate, cetylmethyl borate, And ethyl dibutyl borate. It is also acceptable if the alkyl groups of the borate ester are bonded to the alkyl group in the same molecule or in another molecule. A mixture of two or more of these compounds can be used.

Of these compounds, the borate ester represented by the general formula (2) generates water by reaction. This is particularly preferable. In addition, boric acid esters can be synthesized separately. Boric acid esters can be produced by heating boric acid compounds such as orthoboric acid, metaboric acid, boric anhydride, etc. and alcohol. What was manufactured in this way can also be used conveniently. In addition, the residue of the kettle obtained by reacting a boric acid compound in an alcohol-excess system with an alcohol having a boiling point higher than that of water or an azeotropic composition having a higher boiling point and distilling off the generated water should be used as the alcohol solution. Can do. A boric acid ester having a boiling point lower than that of water can be separated by distillation and used.

[0026] Hydrogen fluoride of component (C) in the method for producing a BF salt of the present invention can be used as an aqueous solution, but anhydrous hydrogen fluoride is preferably used in order to be able to produce a non-aqueous electrolyte. It is done.

[0027] In the method for producing a BF salt of the present invention, the reaction can be carried out without a solvent or in a solvent.

Non-aqueous solvents are preferred as the solvent species when using the solvent, for example, methanolol, ethanol, propanol, isopropanol, butanol, tertiary butanol, ethylene glycol, propylene glycol, glycerin and other alcohols, methyl formate, Acetic acid methylol, ethyl acetate, butyl acetate, methyl 2-hydroxyisobutyrate, esters such as γ-butyrolatatane, ketones such as acetone and methyl ethyl ketone, ethers such as jetyl ether, dimethoxetane, dioxane, tetrahydrofuran, Hydrocarbons such as hexane, benzene, toluene, xylene, carbonates such as dimethyl carbonate, jetyl carbonate, propylene carbonate, amides such as honremamide, Ν, Ν-dimethylformamide, Ν, Ν-dimethylacetamide, etc. Nitriles such as acetonitrile and propionitrile, nitro compounds such as nitromethane, phosphorus compounds such as trimethyl phosphate, and sulfur compounds such as sulfolane and dimethyl sulfoxide.

When the solvent is used, the amount used is usually in the range of 0.001 to 1000 parts by mass, preferably in the range of 0.01 to 100 parts by mass, and more preferably in the range of 1 part by mass of the starting salt compound. It is the range of 1-50 mass parts. If the amount is less than this, the effect of using the solvent is not good.

[0028] The molar equivalent ratio of the raw materials used in the method for producing a BF salt of the present invention is usually in the range of salt compound: hydrogen fluoride: boron compound: 1: 0.1 to 100: 0.1 to L00 Yes, preferably 1 : 0.5 to 5: 0 · 5 to 50, more preferably 1: 0 · 8 to 2: 0 · 8 to 10 If excessive hydrogen fluoride is present, it will remain in the target BF salt to be produced and become an impurity.

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The equivalent molar equivalent ratio is preferably around the same amount. The molar equivalent ratio of the boron compound is preferably around the same amount, but when a boric acid ester is used, the boric acid ester can be added excessively to make a self-solvent without using the solvent.

The order of preparation is not particularly limited, but a method of adding a boron compound and hydrogen fluoride in the presence of a raw material salt compound is preferred.

[0029] The reaction temperature in the production of the BF salt is usually in the range of -50 to 200 ° C, preferably -20 to

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It is in the range of 100 ° C, more preferably in the range of -10 ° C to 60 ° C. If the temperature is lower than this temperature range, the reaction is slow. If the temperature is higher than this temperature range, side reactions may occur.

The reaction pressure is not limited, but is usually in the range of 0 to 10 MPaG, preferably in the range of 0.05 to 5 MPaG, more preferably atmospheric pressure. Since the reaction time varies depending on the raw materials used, it cannot be generally specified, but is usually in the range of 1 minute to 200 hours, preferably in the range of 3 minutes to 150 hours, and more preferably in the range of 5 minutes to 100 hours.

The method for producing the BF salt of the present invention is preferably either a batch method or a distribution method.

Four

Can be implemented.

[0030] The BF salt obtained by the reaction of component (A), component (B) and component (C) is separated and purified.

Four

It is preferable. Separation and purification methods include filtration, recrystallization, extraction, evaporation to dryness, distillation, column separation and the like. If the BF salt is a solid, purification by recrystallization

Four

In this case, the purification power S by extraction is preferable, and a high-purity product can be obtained at low cost. The BF salt

When 4 is separated by filtration, dissolve the raw salt compound and dissolve the BF salt that is produced.

4 If a difficult solvent species is selected as the reaction solvent, the BF salt precipitated as the reaction proceeds

4 Separation is particularly preferable.

[0031] The non-aqueous electrolyte for an electric double layer capacitor of the present invention comprises the components (A), (B) and

It contains the BF salt obtained by the reaction of component (C).

Four

In the non-aqueous electrolyte for an electric double layer capacitor of the present invention, the BF salt as an electrolyte

The use of a non-aqueous solvent is not particularly limited as long as it contains 4, but when the BF salt is solid,

Four

The electrolyte is composed of BF salt dissolved in non-aqueous solvent. Non-aqueous solvents for non-aqueous electrolytes for electric double layer capacitors include, for example, γ-petit-lactone, γ-valerolatatone, esters such as ethyl acetate, ketones such as methyl ethyl ketone, dioxane, tetrahydrofuran, and dimethoxy ester. Ethers such as tan, dimethyl carbonate, jetyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, isobutylene carbonate, carbonate esters such as 1,3-dioxolan-2-one, honolemamide, Ν, ジメチル -dimethylformamide, Ν,アミド -amides such as dimethylacetamide, acetonitrile, propionitryl, 3-methoxypropionitryl, fumaronitrile, glutaronitrile and other nitriles, nitromethane and other nitro compounds, 3_methyl_2_oxazolidinone, etc. Urethanes, trimethyl phosphate Phosphorus compounds, sulfolane, 3-methyl sulfolane, sulfur compounds such Jimechirusu sulfoxide. These nonaqueous solvents can be used alone or in combination of two or more.

These non-aqueous solvents can be used after removing impurities by precision distillation, column treatment, molecular sieve, extraction or the like.

[0032] The concentration of the BF salt in the non-aqueous electrolyte for an electric double layer capacitor of the present invention is usually from 0.:! To 1

Four

0 monolayer / liter, preferably 0.5 to 8 monolayer / liter, more preferably:! To 6 mol / liter. By setting the concentration of BF salt to 0.1 mol / liter or more, a suitable electrolyte solution

Four

Conductivity is obtained, and it is economically advantageous to make it 10 mol / liter or less.

Impurities can be further removed from the thus obtained non-aqueous electrolyte by column treatment, molecular sieve, extraction or the like. In addition, an additive may be added to the electrolyte for the purpose of improving the withstand voltage or improving the safety.

[0033] The non-aqueous electrolyte for an electric double layer capacitor of the present invention contains an BF salt as long as it contains a BF salt.

Four

Although the manufacturing method, shape, etc. of a multilayer capacitor are not specifically limited, The electric double layer capacitor in which the nonaqueous electrolyte of this invention is used is illustrated below.

Usually, an electric double layer capacitor is comprised from an exterior body, a polarizable electrode, a separator, and electrolyte solution.

As the outer package and shape of the electric double layer capacitor, for example, it is possible to assemble in a coin shape, metal shape, cylindrical shape, square shape, aluminum laminate film or plastic bag shape. [0034] The polarizable electrode is composed of activated carbon, a conductive additive, a binder, a collector electrode, and the like.

Examples of the activated carbon include those obtained by activating carbides such as coconut shell, phenol resin, and petroleum pitch with water vapor, carbon dioxide, zinc chloride, potassium hydroxide, and the like.

Examples of the conductive aid include carbon black such as acetylene black, or metal such as aluminum and copper.

Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose, and rubbers.

Examples of the collecting electrode include aluminum, stainless steel, copper, and conductive plastic.

[0035] As a method for producing a polarizable electrode, for example, activated carbon, a conductive aid, and a binder are mixed, and an appropriate solvent such as alcohol is added and kneaded to form a sheet, and the collector electrode is coated with a conductive adhesive or the like. Obtained by sheet molding method to obtain an electrode by pasting, activated carbon, conductive additive and binder mixed with a solvent such as N-methylpyrrolidone to form a slurry, and a thin film is formed on the collector electrode with a doctor blade etc. and dried. It can be manufactured by a coating method. The mixing ratio of the activated carbon, the conductive additive, and the binder is usually 10: 0 · 01 to 5: 0.01 to 5 in mass ratio. These electrodes can be processed on one side or both sides of the collector electrode.

After the polarizable electrode thus obtained is dried, it is placed inside the outer package so as to face each other with a separator interposed therebetween, and impregnated with an electrolytic solution and sealed to assemble an electric double layer capacitor. The drying method and temperature of the electrode are not particularly limited, but are usually 50 to 400 ° C., and can be dried under vacuum.

The separator can be made of paper or plastic such as polyethylene, polypropylene, polyamide, polytetrafluoroethylene.

In the electric double layer capacitor, the mass ratio of the electrolyte solution of the present invention to the polarizable electrode in total of positive and negative electrodes (the mass of the electrolyte solution and the mass of the Z-polarizable electrode) is not limited, but is usually 0.:! To 5, preferably Or 0.5 to 2, particularly preferably 0.7 to 1.5. By setting the mass ratio to 0.1 or more, the electrolyte solution can be spread over the entire electrode, and the capacitance is not reduced and the internal resistance is not increased due to insufficient ions. On the other hand, when the mass ratio is 5 or less, the amount of the electrolyte does not increase and economic efficiency is obtained. Example

[0036] Hereinafter, the present invention will be described more specifically with reference to Examples. The present invention is not limited by these examples.

In the following, ion chromatography was used to analyze the product, and Karl Fischer moisture meter was used to analyze the water content of the electrolyte.

The electrolyte was evaluated using glassy carbon for the working electrode, platinum wire for the counter electrode, and silver wire for the reference electrode, and with a potentiostat, the positive and negative electrodes were swept at a sweep rate of 5 mV / sec to ± 10 β Α. The measurement was performed by a “potential window” in which the absolute values of the reached potentials were summed.

Furthermore, the electric double layer capacitor was manufactured as follows.

After mixing a mixture of activated carbon powder 80 wt%, carbon black 10 mass%, polytetrafluoroethylene 10 mass% obtained by activating mesophase pitch carbonized with potassium hydroxide, a pressure sheet is formed. did. The obtained sheet was punched out into a disk shape and then vacuum-dried at 200 ° C. for 12 hours to obtain a polarizable electrode (diameter 16 mm, thickness 0.4 mm). The electrodes were placed in a stainless steel case facing each other through a paper separator. Thereafter, an electric double layer capacitor cell was prepared by impregnating with the electrolytic solution. The electric double layer capacitor is evaluated by a charge / discharge test in which the cell is fully charged by applying a voltage of up to 2.7V at a constant current of 5mA at 25 ° C and then discharged to 0V at a constant current of 5mA. The initial capacitance (F / cc) was obtained, and then, as an accelerated test, the charge / discharge cycle for 250 hours at 70 ° C was repeated to obtain the capacitance retention rate (%) after acceleration relative to the initial capacitance.

The capacitance was obtained from the discharge energy described in Ikuo Okamura and Nikkan Kogyo Shimbun “Electric Double Layer Capacitor and Storage System Second Edition”.

[0038] <Synthesis of BF salt>

Four

Example 1

40 g of water and 12 g of orthoboric acid (0.2 mol) were placed in a 200 ml eggplant flask made of PTFE (polytetrafluoroethylene) equipped with a stirrer, and 32 g (0.8 mol) of 50 mass% hydrogen fluoride under ice cooling. ), And 41 g (0.2 mol) of jetyldimethylammonium 2-hydroxyisobutyrate (denoted as DE DMA-HBA) was immediately added. After stirring for 3 hours, water was distilled off under reduced pressure. Add ethanol to the residue and recrystallize to recycle the diethyldimethylammonium BF (DEDM

Four

Expressed as A-BF. ) 26 g of white crystals were obtained. The purity of the crystals is 99.2% by mass, the yield is D

Four

It was 69 mol% based on EDMA-HBA.

[0039] Example 2

40 g of ethanol, 41 g of DEDMA-HBA (0.2 monole) and 12 g of noreboric acid (0.2 monole) were charged in the same container as in Example 1, and 16 g (0.8 mol) of hydrogen fluoride was blown under ice cooling. . Stirring was continued for 1 hour, and the precipitated crystals were filtered to obtain 28 g of DEDMA-BF white crystals.

Four

Obtained. The purity of the crystals was 99.8% by mass, and the yield was 75 mol% based on DEDMA-HBA.

[0040] Example 3

The reaction was conducted in the same manner as in Example 2 except that 8.9 g (0.2 mol) of metaboric acid was used instead of orthoboric acid. DEDMA— The purity of BF crystals is 99.8% by mass, and the yield is DEDMA.

Four

It was 73 monole% based on HBA.

[0041] Example 4

The reaction was carried out in the same manner as in Example 2 except that 7.0 g (0.1 mol) of boric anhydride was used in place of orthoboric acid, the reaction temperature was room temperature, and the reaction time was 72 hours. DEDMA—of BF crystals

4 The purity was 99.8% by mass, and the yield was 69% mol based on DEDMA-HBA.

[0042] Example 5

The reaction was performed in the same manner as in Example 2 except that 29 g (0.2 mol) of triethyl borate was used instead of orthoboric acid. The purity of DEDMA-BF crystals is 99.8% by mass, and the yield is DED.

Four

MA—79 mol% based on HBA.

[0043] Example 6

The reaction was carried out in the same manner as in Example 1 except that triethyl borate (21 g, 0.2 mol) was used instead of triethyl borate. The purity of DEDMA—BF crystals is 99.8% by mass, and the yield is DEDM.

Four

It was 54 monole% based on A-HBA.

[0044] Example 7

40 g of ethanol and 35 g (0.2 mol) of jetyldimethylammonium methyl carbonate and 29 g (0.2 mol) of triethinole borate were placed in a PTFE 200 ml eggplant flask equipped with a stirrer. Then, 16 g (0.8 mol) of hydrogen fluoride was blown in under ice cooling. Obtained DEDMA—BF results

The purity of the 4 crystals was 99.8% by mass, and the yield was 75% by mole based on jetyldimethylammonium methyl carbonate.

[0045] Example 8

The reaction was performed in the same manner as in Example ₂ except that methyl ₂ -hydroxyisobutyrate was used instead of ethanol. DEDMA— The purity of BF crystals is 99.8% by mass, and the yield is DEDMA—

Four

It was 20 mol% based on HBA.

[0046] Example 9

The reaction was performed in the same manner as in Example 5 except that ethanol was not used and 73 g (0.5 mol) of triethyl borate was used as the self-solvent. The purity of the DEDMA-BF crystal is 99.8% by mass.

Four

The rate was 81 mol% based on DEDMA-HBA.

[0047] Examples 10 to 16

In Example 2, the reaction was carried out in the same manner as in Example 2 except that the starting salt compound (DEDMA-HBA) was changed to that shown in Table 1. The obtained BF salt and its purity and

Four

The yield is shown in Table 1.

In Table 1, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, and Ph represents a phenol group.

[0048] [Table 1] 1 table

[0049] Example 17

Methanolol 40 g, 1-ethyl 3-methylimidazolium 2-hydroxyisobutyrate 43 g (0.2 monole) and 21 g trimethyl borate (0.2 mol) were placed in a PTFE 20 Oml eggplant flask equipped with a stirrer, and 16 g (0.8 mol) of hydrogen fluoride was blown in with ice cooling. . Reaction liquid After distilling off the low boiling point, the reaction solution was washed with ethyl acetate to obtain 1-ethyl-3-methylimidazolium-BF liquid. The purity is 99.8% by mass, the yield is 1_ethyl-3-methylimidazoli

Four

96 mole ⁰ / umum carbonate standard. Met.

[0050] Example 18

Example 1 except that 20% by weight triethylmethylammonium hydroxide (denoted as TEMA-OH) 133 g (0.2 monole) in place of DEDMA-HBA and ethanol 40 g in place of water The reaction was carried out in the same manner. Triethylmethylammonium BF (T

Four

Expressed as EMA-BF. ) The purity of the crystal is 99.8 mass%, and the yield is 76 based on TEMA-OH.

Four

Monore%.

[0051] Example 19

The reaction was carried out in the same manner as in Example 11 except that TEMA-OH and orthoboric acid were added to ethanol and then 50% by mass of hydrogen fluoride was added dropwise. Precipitation occurred when TEMA OH and orthoboric acid were charged, and the precipitation disappeared when hydrogen fluoride was added dropwise. The purity of TEMA—BF crystals is 99.8% by mass, and the yield is TEMA—OH group.

Four

The equivalent was 74 mol%.

[0052] Example 20

The reaction was carried out in the same manner as in Example 11 except that TEMA-OH and 50% by mass hydrogen fluoride were added to ethanol in the order of addition of onoleboric acid. The purity of TEMA-BF crystal was 99.8% by mass, and the yield was 71 mol% based on TEMA-OH.

Four

[0053] Comparative Example 1

Water 40g, DEDMA-HBA41g a (0.2 mol) and 42 mass ^_0/0 fluoroboric acid solution 29 g (0.2 mol) were charged to a PTFE 200ml eggplant flask equipped with a stirrer, under ice-cooling 5 32 g (0.8 mol) of 0 mass% aqueous hydrogen fluoride solution was added dropwise. Stirring was continued for 1 hour, but no crystals were precipitated. The reaction solution was heated with an evaporator and concentrated under reduced pressure, and ethanol was added as a recrystallization solvent and cooled to precipitate DEDMA-BF crystals. If an expensive and highly corrosive borohydrofluoric acid aqueous solution is used, the reaction cannot be carried out in a non-aqueous system, and the BF salt is highly soluble in water, so the reaction solution must be heated and concentrated.

Four

Met.

[0054] Comparative Example 2

In a 200 ml Hastelloy C HF—BF blending tank with a stirrer, 64 g ethanol (l

Three

4 mol) was charged, 10 g (0.5 mol) of hydrogen fluoride was added dropwise while cooling to 5 ° C, and then 33 g (0.5 mol) of BF gas was blown to prepare an ethanol solution of HF-BF. Stirrer

3 3

DEDMA_HBA103g (0.5 mol) and ethanolol 88g (l.9 mol) were added to a 500 ml Hastelloy C reaction vessel with a mark to prepare an ethanolic solution of DEDMA-HBA.

[0055] The ethanol solution of HF-BF prepared above was added to the ethanol solution of DEDMA-HBA.

Three

Dropped into the solution and stirred for 1 hour. The precipitated crystals were filtered and white DEDMA-BF crystals 77g

Four

Got. The purity of the crystals is 99.8% by mass, and the yield is 81 mol% based on DEDMA-HBA.

[0056] Comparative Example 3

The reaction was carried out in the same manner as in Comparative Example 2, except that 107 g (0.5 mol) of 1-ethyl 3-methylimidazolium methyl 2-hydroxyisobutyrate was used instead of DEDMA-HBA. Reaction liquid After distilling off the low boiling point, the reaction solution was washed with ethyl acetate to obtain 1-ethyl-3-methylimidazolium-BF liquid. The purity is 99.7% by mass, the yield is 1-ethyl-3-methylimidazoli

Four

It was 94 mol% based on ummethyl carbonate.

[0057] <Preparation and Evaluation of Electrolytic Solution>

Example 21

After the DEDMA-BF obtained in Example 5 was dried in a vacuum dryer at 100 ° C for 10 hours,

Four

DEDMA—A propylene power-bonate (PC) that was brought into a glove box with a dew point of 30 ° C and precision-distilled was dissolved at a concentration of 1.8 mol / liter (hereinafter abbreviated as M / mol). A BF ZPC electrolyte was prepared. Electrolyte moisture is 20ppm or less

Four

I got it.

The results of measuring the potential window of the prepared electrolyte are shown in Table 2.

[0058] Examples 22-24 Using the DEDMA-BF obtained in the examples and comparative examples shown in Table 2, a 1.8M DEDMA-BF / PC electrolyte was prepared in the same manner as in Example 21. The water content of the electrolyte was 20 ppm or less.

[0059] Comparative Example 4

DEDMA—BF obtained in Comparative Example 2 was used in the same manner as in Example 21.

DMA-BF / PC electrolyte was prepared. The water content of the electrolyte was 20 ppm or less.

[0060] [Table 2]

Table 2

[0061] Examples 25-30

Using the BF salt obtained in the example shown in Table 3, a PC electrolyte solution having the concentration shown in Table 3 was prepared in the same manner as in Example 21. The water content of the electrolyte was 20 ppm or less. Table 3 shows the results of measuring the potential window of the prepared electrolyte.

[0062] [Table 3]

[0063] Example 31 Using 1-ethyl-3-methylimidazolium BF obtained in Example 17, Example 21

Four

1M 1-Ethyl-3-methylimidazolium-BF / PC electrolyte was prepared

Four

It was. The water content of the electrolyte was 20 ppm or less.

Table 4 shows the results of measuring the potential window of the prepared electrolyte.

[0064] Comparative Example 5

1_Ethyl_3-methylimidazolium-BF obtained in Comparative Example 3 was used in Example 21, and

Four

In the same manner, 1M 1_ethyl-3-methylimidazolium_BF / PC electrolyte was prepared.

Four

. The water content of the electrolyte was 20 ppm or less.

Table 4 shows the results of measuring the potential window of the prepared electrolyte. As shown in Table 4, 1_ethyl-3-methylimidazolium-BF electrolyte with a potential window equivalent to that of the conventional method is

4 Manufacturable.

[0065] [Table 4] Table 4

[0066] <Evaluation of Electric Double Layer Capacitor>

Examples 32-34, Comparative Example 6

Manufactured according to the examples and comparative examples shown in Table 5. 1. Using 8M DEDMA-BF electrolyte

4 Electric double layer capacitors were evaluated. The results are shown in Table 5. Use HF-BF

3 The method of Comparative Example 4 to be used is a non-aqueous reaction, and a high yield of BF salt is obtained, and the electrolyte is highly pure.

Four

However, expensive and highly toxic BF gas is used, and a pressure-resistant device is required.

Three

[0067] [Table 5]

^ 5 table

Electrolyte production Initial capacitance After accelerated test

(F c) Capacitance retention ratio (>> /.) Example 3 2 Example 2 1 2 5. 9 8 7.5 Example 3 3 Example 2 2 2 5. 8. 8 8 7. 8 Example 3 4 Example 2 3 2 5 .5 8 77.0 Comparative Example 6 Comparative Example 4 2 5 .8 8 7 .2 As is clear from the examples and comparative examples, the electrolytic solution obtained by the present invention has a high purity equivalent to the electrolytic solution produced by non-aqueous HF-BF, and has an electric double layer carrier.

Three

It was useful as an electrolyte for pasita. Thus, according to the present invention, an electrolytic solution can be produced safely and inexpensively by using a boron compound containing boric acid. In particular, by using boric acid ester, a non-aqueous and high-purity electrolyte can be obtained.

Industrial applicability

[0069] According to the present invention, a high-purity BF salt used in an electrolytic solution for an electric double layer capacitor

4 can be produced industrially advantageously without using expensive and highly toxic BF gas.

Three

Further, in the method for producing a BF salt in the non-aqueous system of the present invention, an electric double layer capacitor is used.

Four

It has good physical properties as a non-aqueous electrolyte and can be advantageously produced.

In particular, by using a boric acid ester compound as a boron source, it is possible to eliminate the need for a solvent that does not produce by-product water in the system, and a high-purity BF salt can be produced very advantageously industrially.

Four

Furthermore, by using alkylammonium organic acid salt obtained by the reaction of alkylamine and carboxylic acid ester as a raw material, the purification process can be simplified, and by using hydroxycarboxylic acid ester as carboxylic acid ester. The by-produced hydroxycarboxylic acid can be esterified and recycled to the quaternization process, and the BF salt can be produced industrially very advantageously.

Four

Therefore, according to the present invention, a BF salt having good physical properties as a non-aqueous electrolyte for an electric double layer capacitor can be produced industrially very advantageously, and the electric double layer carrier having high performance can be produced.

Four

A non-aqueous electrolyte for pasita can be advantageously obtained economically.

Claims

Claims [1] (A) Salt compound represented by general formula (1), Q + X— (1) (where Q + represents an ion or metal ion, and X— represents an inorganic acid excluding BF— (Represents ion, organic acid ion or hydroxide ion) (B) One selected from the group consisting of orthoboric acid, metaboric acid, tetraboric acid, boron oxide and boric acid ester represented by the general formula (2) The above boron compound and B (OR1) (OR2) (OR3) (2) (wherein R1 is an alkyl group having! -10 to C10, R2 and R3 are a hydrogen atom or an alkyl group having 1 to 10 carbons) Wherein R1, R2 and R3 may be the same or different. (C) A process for producing a boron tetrafluoride salt represented by the general formula (3), characterized by reacting hydrogen fluoride. Q + BF― (3)

(In the formula, Q ⁺ is the same as in general formula (1).)

[2] In general formulas (1) and (3), Q ⁺ is a lithium ion or an alkylammonium ion

2. The method for producing a boron tetrafluoride salt according to claim 1, wherein the ion is one or more ions selected from the group consisting of alkylphosphonium ions and imidazolium ions.

[3] The boron tetrafluoride salt according to claim 2, wherein in the general formulas (1) and (3), Q ⁺ is a tetraethylammonium ion, a trimethylethylammonium ion, or a jetyldimethylammonium ion. Production method.

4. The method for producing a boron tetrafluoride salt according to claim 2, wherein in the general formulas (1) and (3), Q ⁺ is an imidazolium ion.

[5] The method for producing a boron tetrafluoride salt according to any one of [1] to [4], wherein in the general formula (1), X— is an organic acid ion.

[6] The method for producing a boron tetrafluoride salt according to any one of [1] to [5], wherein the component (A) is obtained by reacting an alkylamine with an organic acid ester or dialkyl carbonate.

[7] The component (A) is obtained by reacting an alkylamine with a hydroxycarboxylic acid ester. The method for producing a boron tetrafluoride salt according to claim 6, wherein

[8] The component (A), the component (B), and the component (C) are reacted in the presence of a nonaqueous solvent.

8. The method for producing a boron tetrafluoride salt according to any one of 7 above.

[9] The method for producing a boron tetrafluoride salt according to [8], wherein the boric acid ester represented by the general formula (2) is used as the component (B).

[10] Use a borate ester represented by the general formula (2) as a solvent, (A) component, (B) component and

The method for producing a boron tetrafluoride salt according to any one of claims 7 to 7, wherein the component (C) is reacted.

[11] A boron tetrafluoride salt produced by the method according to any one of claims 1 to 10.

[12] A nonaqueous electrolytic solution for an electric double layer capacitor, comprising the boron tetrafluoride salt according to claim 11.

[13] A method for producing a nonaqueous electrolytic solution for an electric double layer capacitor, wherein the boron tetrafluoride salt according to the above item 11 is dissolved in a nonaqueous solvent.