JP2011146670A - Electrolytic solution for electrolytic capacitor, and electrolytic capacitor using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic solution for an electrolytic capacitor, which exhibits high conductivity and high spark voltage at the same time, and an electrolytic capacitor produced using the same. <P>SOLUTION: Specifically disclosed is an electrolytic solution for an aluminum electrolytic capacitor, which includes electrolytes (C) comprising a borate anion expressed by formula (1) and an ammonium cation (B) in an aprotic solvent (A). The aprotic solvent (A) is preferably at least one kind selected from a group consisting of γ-butyrolactone and sulfolane, and the ammonium cation (B) is preferably an amidinium cation or a tertiary ammonium cation. The electrolyte (C) is preferably included 1 to 10 wt.% based on a total weight of (C) and (A). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrolytic solution used for an electrolytic capacitor and an electrolytic capacitor using the electrolytic solution.

  In recent years, with the space saving and high temperature of the surrounding environment where capacitors are used, when the conductivity is high and the spark voltage is high, that is, it is difficult to destroy the aluminum conversion coating of the electrode, and the aluminum conversion coating has a defect, There is a demand for an electrolytic solution that is excellent in film repairing ability to repair this, and that has low characteristic deterioration at high temperatures. On the other hand, an electrolytic solution using boric acid has been proposed. For example, an electrolytic solution containing ethylene glycol as a main solvent and containing boric acid, an organic acid or a salt thereof (for example, Patent Document 1), or an electrolytic solution using glycolate oxalate borate anion (for example, Patent Document 2) is known. Yes.

JP2000-182896 JP-A-2005-116601

The electrolytic solution containing boric acid, an organic acid or a salt thereof using the above-mentioned ethylene glycol as a main solvent in the prior art is anion of boric acid ester by boric acid and ethylene glycol being esterified. Absent. For this reason, the effect of improving the spark voltage is reduced, and the viscosity of the electrolyte is increased due to esterification, and the conductivity is also lowered. When the solvent is water, borate anions are formed, but there is a drawback that the electrode foil is hydrated and the capacitance is lowered. Also, the electrolyte using the glycolatooxalate borate anion also had a low spark voltage because it was not a borate anion.

That is, the present invention seeks to solve the problems associated with the prior art as described above, and provides an electrolytic solution for an electrolytic capacitor that achieves both high conductivity and high spark voltage, and an electrolytic capacitor using the electrolytic solution. Is to provide.

As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention. That is, the present invention provides an electrolytic solution for an aluminum electrolytic capacitor containing an electrolyte (C) comprising a borate anion represented by the general formula (1) and an ammonium cation (B) in an aprotic solvent (A); This is an aluminum electrolytic capacitor using a liquid.

  The electrolytic capacitor using the electrolytic solution of the present invention can increase the spark voltage while maintaining high electrical conductivity.

The electrolytic solution of the present invention is characterized by containing an electrolyte (C).
In the electrolyte (C), the borate anion represented by the general formula (1) has a carrier effect of the hydroxyl anion and plays a role in promoting the repair reaction of the aluminum chemical conversion film. As a result, the spark voltage is increased. Moreover, since the effect is high, it is possible to increase the spark voltage while maintaining high electrical conductivity.
Since the effect of the electrolyte (C) is high, it is preferably 1 to 10 wt% (hereinafter referred to as wt%), more preferably 2 to 6 wt based on the total weight of the electrolyte (C) and (A). %, The effect of increasing the spark voltage can be exhibited. When the addition amount is 1 to 10 wt%, the solubility of (C) in the electrolytic solution is good. In this case, the electrolyte is preferably used in combination with the electrolyte (E) described below in addition to the electrolyte (C).

In the present invention, the ammonium cation (B) includes amidinium cation, quaternary ammonium cation, tertiary ammonium cation, secondary ammonium cation, primary ammonium cation, ammonium cation (NH ₄ ⁺ ) and the like. included. The ammonium cation (B) may be used alone or in combination of two or more.

Examples of the amidinium cation include a cyclic amidinium cation (1) imidazolinium cation and (2) imidazolium cation (3) diazabicycloalkenium cation.

(1) Imidazolinium cation 1,2,3,4-tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2,4-diethylimidazolinium 1,2-dimethyl-3,4-diethylimidazolinium, 1-methyl-2,3,4-triethylimidazolinium, 1,2,3,4-tetraethylimidazolinium, 1,2,3- Trimethylimidazolinium, 1,3-dimethyl-2-ethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1,2,3-triethylimidazolinium, 4-cyano-1,2, 3-trimethylimidazolinium, 3-cyanomethyl-1,2-dimethylimidazolinium, 2-cyanomethyl-1,3-dimethylimidazolinium, 4-acetate Til-1,2,3-trimethylimidazolinium, 3-acetylmethyl-1,2-dimethylimidazolinium, 4-methylcarbooxymethyl-1,2,3-trimethylimidazolinium, 3-methylcarbooxy Methyl-1,2-dimethylimidazolinium, 4-methoxy-1,2,3-trimethylimidazolinium, 3-methoxymethyl-1,2-dimethylimidazolinium, 4-formyl-1,2,3- Trimethylimidazolinium, 3-formylmethyl-1,2-dimethylimidazolinium, 3-hydroxyethyl-1,2-dimethylimidazolinium, 4-hydroxymethyl-1,2,3-trimethylimidazolinium, 2 -Hydroxyethyl-1,3-dimethylimidazolinium and the like.

(2) Imidazolium cation 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4- Tetramethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 1-ethyl-2,3-dimethyl-imidazolium, 1,2,3-triethylimidazolium, 1,2,3,4-tetraethylimidazolium Lithium, 1,3-dimethyl-2-phenylimidazolium, 1,3-dimethyl-2-benzylimidazolium, 1-benzyl-2,3-dimethyl-imidazolium, 4-cyano-1,2,3-trimethyl Imidazolium, 3-cyanomethyl-1,2-dimethylimidazolium, 2-cyanomethyl-1,3-dimethyl-imidazole Zorium, 4-acetyl-1,2,3-trimethylimidazolium, 3-acetylmethyl-1,2-dimethylimidazolium, 4-methylcarbooxymethyl-1,2,3-trimethylimidazolium, 3-methylcarbo Oxymethyl-1,2-dimethylimidazolium, 4-methoxy-1,2,3-trimethylimidazolium, 3-methoxymethyl-1,2-dimethylimidazolium, 4-formyl-1,2,3-trimethylimidazolium Rium, 3-formylmethyl-1,2-dimethylimidazolium, 3-hydroxyethyl-1,2-dimethylimidazolium, 4-hydroxymethyl-1,2,3-trimethylimidazolium, 2-hydroxyethyl-1, 3-dimethylimidazolium and the like.

(3) Diazabicycloalkenium cation 1,4-diazabicyclo [3,2,0] -4-heptanium, 1,4-diazabicyclo [3,3,0] -4-octenium, 1,7-diazabicyclo [4 , 3,0] -6-nonenium, 1,8-diazabicyclo [5,3,0] -7-decenium, 1,9-diazabicyclo [6,3,0] -8-undecenium, 1,5-diazabicyclo [ 4,2,0] -5-octenium, 1,5-diazabicyclo [4,3,0] -5-nonenium, 1,5-diazabicyclo [4,4,0] -5-decenium, 1,8-diazabicyclo [5,4,0] -7-undecenium, 1,9-diazabicyclo [6,4,0] -8-dodecenium.

As the quaternary ammonium cation, a tetraalkylammonium cation having an alkyl group having 1 to 4 carbon atoms which may be linked to each other to form a ring {tetramethylammonium, tetraethylammonium, ethyltrimethylammonium, triethylmethylammonium, N, N-dimethylpyrrolidinium, N, N-dimethylpiperidinium, spirobipyrrolidinium, etc.}.
As the tertiary ammonium cation, a trialkylammonium cation having a C 1-4 alkyl group which may be linked to each other to form a ring {triethylammonium, diethylmethylammonium, ethyldimethylammonium, trimethylammonium, N-methyl Pyrrolidinium, N-methylpiperidinium, etc.} and the like.
Examples of the secondary ammonium cation include dialkylammonium cations {diethylammonium, methylethylammonium, dimethylammonium, pyrrolidinium, piperidinium, etc.} having a C1-4 alkyl group that may be linked to each other to form a ring. It is done.
Examples of the primary ammonium cation include monoalkylammonium cations having an alkyl group having 1 to 4 carbon atoms {such as ethylammonium and methylammonium}.

Of the above cations (B), an amidinium cation or a tertiary ammonium cation is preferable from the viewpoint of the temporal stability of conductivity. Among the amidinium cations, a cyclic amidinium cation is preferable, (1) an imidazolinium cation and (2) an imidazolium cation, and more preferably 1,2,3,4-tetramethylimidazoli. And a 1-ethyl-2,3-dimethylimidazolium cation, a 1-ethyl-3-methylimidazolium cation, and a 1-ethyl-2,3-dimethylimidazolium cation.
Among the tertiary ammonium cations, preferred are trialkylammonium cations having an alkyl group having 1 to 4 carbon atoms which may be linked to each other to form a ring, more preferably a triethylammonium cation or an ethyldimethylammonium cation. .

The method for synthesizing the electrolyte (C) is preferably a method in which an ammonium salt {monomethyl carbonate, hydroxide salt, etc.) and boric acid are mixed with water to obtain a salt of an ammonium cation and a borate anion.

The aprotic solvent (A) in the present invention is exemplified below, and two or more kinds can be used in combination. If necessary, water may be used in combination with these aprotic solvents.
The content of (A) is preferably 90 to 99 wt%, more preferably 94 to 98 wt%, based on the total weight of the electrolytes (C) and (A).

(1) Ethers;
Ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.

(2) Amides;
Formamides (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, etc.), acetamides (N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N , N-diethylacetamide), propionamides (N, N-dimethylpropionamide, etc.), hexamethylphosphorylamide, etc.

(3) oxazolidinones;
N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, and the like.

(4) Lactones;
γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, δ-valerolactone, and the like.

(5) Nitriles;
Acetonitrile, acrylonitrile, etc.

(6) carbonates;
Ethylene carbonate, propylene carbonate, etc.

(7) Other aprotic solvents;
Dimethyl sulfoxide, sulfolane, dimethyl sulfone, ethyl methyl sulfone, ethyl propyl sulfone, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffinic solvents (normal paraffin) , Isoparaffin).

Among these aprotic solvents (A), a solvent having a product of an acceptor number and a donor number of 500 or less is preferable, and a solvent of 350 or less is more preferable so as not to coordinate with a borate anion. Specific examples include γ-butyrolactone, sulfolane, propylene carbonate, N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide and the like.

The acceptor number (hereinafter sometimes referred to as AN) can be expressed by the following formula.
Acceptor number = (δ _corr · 2.348)
However, in the formula, δ _corr represents a correction value of a difference in volume magnetic susceptibility with another solvent when hexane is used as a reference. The acceptor number is an index that represents a measure of the electron acceptability of the solvent.

The donor number (hereinafter sometimes referred to as DN) is defined as the molar enthalpy value of the reaction with 10 ⁻³ M SbCl _{5 in} dichloroethane. The donor number is an index that represents a measure of the electron donating property of the solvent.

Among the aprotic solvents (A), those having a solubility parameter of (A) (hereinafter sometimes referred to as SP value) of 10 to 20 are preferable.
Specific examples include γ-butyrolactone, sulfolane, propylene carbonate, ethylene carbonate, N-methylpyrrolidone, N-methylacetamide, N, N-dimethylformamide and the like.

The SP value is calculated by the Fedors method.
The SP value can be expressed by the following equation.
SP value = (ΔH / V) ^1/2
In the formula, ΔH represents the heat of molar evaporation (cal), and V represents the molar volume (cm ³ ).
ΔH and V are the sum of the heat of molar evaporation (ΔH) of the atomic group described in “POLYMER ENGINEERING AND FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (Pages 151 to 153)”. The total molar volume (V) can be used.
Those having a close numerical value are easy to mix with each other (high compatibility), and those having a close numerical value are indices that indicate that they are difficult to mix.

(A) is more preferably γ-butyrolactone, sulfolane, or a mixed solvent of γ-butyrolactone and sulfolane, particularly preferably a mixed solvent of γ-butyrolactone, γ-butyrolactone and sulfolane.

  The electrolyte solution of the present invention preferably contains water. When water is contained, the chemical property of the capacitor member {aluminum oxide foil or the like as the anode foil} {the property of forming an oxide film and repairing it if there is a defect portion on the surface of the anode foil} can be improved. On the other hand, when there is much content of water, vapor pressure will become high and it will become impossible to use at high temperature. Therefore, when water is contained, the content of water is preferably 0.01 to 10 wt%, more preferably 0.1 to 0.1% based on the total weight of the electrolyte (C) and the aprotic solvent (A). 5 wt%, particularly preferably 1 to 5 wt%.

As for moisture, JIS K0113: 2005 “8. Karl Fischer titration method, 8.1 volumetric titration method” {corresponding international standard ISO760: 1978; the disclosure content disclosed therein is incorporated into the present application by reference. } Is measured in accordance with.

The electrolyte in the electrolytic solution may be used in combination with components other than the electrolyte (C). The cation of the electrolyte (E) used in combination is an ammonium cation (B), and as anions, anions of various organic acids and / or inorganic acids that are usually used in an electrolytic solution can be used. Examples of the organic acid and inorganic acid include the following (1) to (6). The anion may be used alone or in combination of two or more.
The electrolyte (E) is preferably 0 to 1000 wt%, more preferably 10 to 500 wt%, more preferably 50 to 500 wt% based on the weight of the electrolyte (C).

(1) Carboxylic acids / C2-C15 divalent to tetravalent polycarboxylic acids: aliphatic polycarboxylic acids [saturated polycarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, Speric acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, 1,6-decanedicarboxylic acid, etc.), unsaturated polycarboxylic acid (maleic acid, fumaric acid, itaconic acid, etc.)], aromatic polycarboxylic acid [Phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.], S-containing polycarboxylic acids [thiodibropionic acid, etc.].
C2-C20 oxycarboxylic acid: aliphatic oxycarboxylic acid [glycolic acid, lactic acid, tartaric acid, castor oil fatty acid, etc.]; aromatic oxycarboxylic acid [salicylic acid, mandelic acid, etc.].
C1-C30 monocarboxylic acid: aliphatic monocarboxylic acid [saturated monocarboxylic acid (formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, uraryl Acid, myristic acid, stearic acid, behenic acid, etc.), unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, crotonic acid, oleic acid, etc.)]; aromatic monocarboxylic acids [benzoic acid, cinnamic acid, naphthoic acid, etc. ].

(2) Phosphate ester anion Here, the phosphate ester anion refers to a monoalkyl phosphate ester and a dialkyl phosphate ester having 1 to 15 carbon atoms.
Mono and dimethyl phosphate, mono and diethyl phosphate, mono and diisopropyl phosphate, mono and dibutyl phosphate, mono and di- (2-ethylhexyl) phosphate, mono and diisodecyl phosphate, and the like.

(3) Phenols and monohydric phenols (including phenols and naphthols): Phenol, alkyl (C1-15) phenols (cresol, xylenol, ethylphenol, n- or isopropylphenol, isododecylphenol, etc.) , Methoxyphenols (eugenol, guaiacol, etc.), α-naphthol, β-naphthol, cyclohexylphenol, etc .;
Polyhydric phenol: catechol, resorcin, pyrogallol, phloroglucin, bisphenol A, bisphenol F, bisphenol S, etc.

(4) Sulfonic acid / alkyl (C1-15) benzenesulfonic acid (p-toluenesulfonic acid, nonylbenzenesulfonic acid, dodecylbenzenesulfonic acid, etc.), sulfosalicylic acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. .

(5) Inorganic acid / phosphoric acid, boron tetrafluoride, perchloric acid, hexafluorophosphoric acid, hexafluoroantimonic acid, hexafluoroarsenic acid, etc.

(6) Others: Imide anions such as methanesulfonyl imide imide, and methide anions such as methanesulfonyl methoxide trifluoride.
Among the anions of the electrolyte (E), preferred are (1) carboxylic acids, (2) phosphate ester anions (mono- and dialkyl phosphate esters of alkyl groups having 1 to 15 carbon atoms) [hereinafter, ( The anion electrolyte of 1) and (2) is defined as an electrolyte (E1). More preferred are (2) phosphate ester anions, and particularly preferred are diethyl phosphate anions and dibutyl phosphate anions.
When the electrolyte (E1) and the electrolyte (C) are used in combination as the electrolyte, it is preferable in that the effect of increasing the temporal stability of the conductivity at high temperatures is exhibited.

  The pH of the electrolytic solution of the present invention is usually 3 to 12, preferably 4 to 11. When producing the electrolyte (A), conditions are selected so that the pH of the electrolytic solution is within this range. The pH of the electrolytic solution is an analytical value of 25 ° C. of the electrolytic solution stock solution.

  If necessary, various additives usually used in the electrolytic solution can be added to the electrolytic solution of the present invention. Examples of the additive include nitro compounds (for example, o-nitrobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol, p-nitrophenol, etc.). The addition amount is preferably 5 wt% or less, particularly preferably 0.1 to 2 wt%, based on the weight of the electrolytic solution, from the viewpoint of specific conductivity and solubility in the electrolytic solution.

In addition to the method of dissolving the electrolyte (C) in the aprotic solvent (A), the electrolytic solution is prepared by adding the boric acid and water after dissolving the electrolyte (E) in the aprotic solvent (A). Then, the electrolyte (C) may be prepared by performing anion exchange in the electrolytic solution.

  The electrolytic solution of the present invention is suitable for an aluminum electrolytic capacitor. The aluminum electrolytic capacitor is not particularly limited. For example, it is a scraped electrolytic capacitor, and a separator is interposed between an anode (aluminum oxide foil) in which aluminum oxide is formed on the anode surface and a cathode aluminum foil. For example, a capacitor formed by winding is used. A separator is impregnated with the electrolytic solution of the present invention as a driving electrolytic solution, housed in a bottomed cylindrical aluminum case together with a positive electrode, and then the aluminum case opening is sealed with a sealing rubber to form an electrolytic capacitor. Can do.

  Next, specific examples of the present invention will be described, but the present invention is not limited thereto.

<Production Example 1>
By adding 2,4-dimethylimidazoline (0.1 mol) dropwise to a methanol solution (74 wt%) of dimethyl carbonate (0.2 mol) and stirring at 120 ° C. for 15 hours, 1,2,3,4- A methanol solution of tetramethylimidazolinium methyl carbonate salt was obtained.

  Boric acid (manufactured by Kanto Chemical Co., Inc.) (0.1 mol) is dissolved in water (1 mol), and a methanol solution of 1,2,3,4-tetramethylimidazolinium methyl carbonate salt (0.1 mol) is further added. In addition, a salt exchange reaction was performed by stirring for 1 hour. Furthermore, methanol and water were distilled off at a reduced pressure of 1.0 kPa or less and 100 ° C. to obtain an electrolyte (C-1) {1,2,3,4-tetramethylimidazolinium borate anion}. .

<Production Example 2>
By adding 1-ethylimidazole (0.1 mol) dropwise to a methanol solution (74 wt%) of dimethyl carbonate (0.1 mol) and stirring at 130 ° C. for 70 hours, 1-ethyl-3-methylimidazolium. A methanol solution of methyl carbonate salt was obtained. In the same manner as in Production Example 1, an electrolyte (C-2) {1-ethyl-3-methylimidazolium / borate anion} was obtained.

<Production Example 3>
Boric acid (manufactured by Kanto Chemical Co., Inc.) (0.1 mol) is dissolved in water (1 mol), an aqueous solution (50 wt%) of triethylamine (0.1 mol) is further added, and the mixture is stirred for 1 hour to cause a salt exchange reaction. It was. Furthermore, water was distilled off at a reduced pressure of 1.0 kPa or less and 100 ° C. to obtain an electrolyte (C-3) {triethylammonium / borate anion}.

<Production Example 4>
Salt exchange is performed by dissolving boric acid (manufactured by Kanto Chemical Co., Inc.) (0.1 mol) in water (1 mol), adding an aqueous solution (60 wt%) of ethyldimethylamine (0.1 mol), and stirring for 1 hour. Reacted. Furthermore, water was distilled off at a reduced pressure of 1.0 kPa or less and 100 ° C. to obtain an electrolyte (C-4) {ethyldimethylammonium / borate anion}.

<Production Example 5>
Triethyl phosphate (0.1 mol) was added to a methanol solution of 1,2,3,4-tetramethylimidazolinium methyl carbonate salt (0.1 mol), water (0.3 mol) was added, and 100 ° C. By stirring for 100 hours, triethyl phosphate was hydrolyzed and a salt exchange reaction was performed to obtain a methanol solution of 1,2,3,4-tetramethylimidazolinium diethylphosphate monoanion. The above solution was heated at a reduced pressure of 1.0 kPa or less at 50 ° C. until the distillation of methanol disappeared, the methanol was distilled off, the temperature was raised from 50 ° C. to 100 ° C., and the mixture was heated for 30 minutes to monomethyl carbonate (HOCO2CH3), methanol and carbon dioxide (methanol and carbon dioxide are slightly produced by thermal decomposition of monomethyl carbonate. These are hereinafter abbreviated as by-products) to distill off the electrolyte (E-1). {1,2,3,4-tetramethylimidazolinium diethylphosphate monoanion} was obtained.

<Production Example 6>
Tributyl phosphate (0.1 mol) was added to a methanol solution of 1,2,3,4-tetramethylimidazolinium methyl carbonate salt (0.1 mol), water (0.3 mol) was added, and 100 ° C. By stirring for 100 hours, tributyl phosphate was hydrolyzed and a salt exchange reaction was performed to obtain a methanol solution of 1,2,3,4-tetramethylimidazolinium dibutyl phosphate monoanion. The above solution was heated at a reduced pressure of 1.0 kPa or less at 50 ° C. until the distillation of methanol disappeared, the methanol was distilled off, the temperature was raised from 50 ° C. to 100 ° C., and the mixture was heated for 30 minutes to monomethyl carbonate (HOCO2CH3), methanol and carbon dioxide (methanol and carbon dioxide are slightly generated by thermal decomposition of monomethyl carbonate. These are hereinafter abbreviated as by-products) to distill off the electrolyte (E-2). {1,2,3,4-tetramethylimidazolinium dibutyl phosphate monoanion} was obtained.

<Production Example 7>
Triethyl phosphate (0.1 mol), triethylamine (0.1 mol), and water (0.3 mol) are placed in a pressure vessel and reacted at 100 ° C. for 100 hours to hydrolyze triethyl phosphate and undergo a salt exchange reaction. And a methanol solution of triethylammonium diethyl phosphate monoanion was obtained. The above solution was heated at a reduced pressure of 1.0 kPa or less at 50 ° C. until the distillation of methanol disappeared, and after the methanol was distilled off, the temperature was raised from 50 ° C. to 100 ° C. and heated for 30 minutes to volatilize components. Was distilled off to obtain an electrolyte (E-3) {triethylammonium diethyl phosphate monoanion}.

<Production Example 8>
Tributyl phosphate (0.1 mol), triethylamine (0.1 mol), and water (0.3 mol) are placed in a pressure vessel and reacted at 100 ° C. for 100 hours to hydrolyze tributyl phosphate and undergo a salt exchange reaction. And a methanol solution of triethylammonium dibutyl phosphate monoanion was obtained. The above solution was heated at a reduced pressure of 1.0 kPa or less at 50 ° C. until the distillation of methanol disappeared, and after the methanol was distilled off, the temperature was raised from 50 ° C. to 100 ° C. and heated for 30 minutes to volatilize components. Was distilled off to obtain an electrolyte (E-4) {triethylammonium dibutyl phosphate monoanion}.

<Production Example 9>
Triethyl phosphate (0.1 mol), ethyldimethylamine (0.1 mol), and water (0.3 mol) are placed in a pressure vessel and reacted at 100 ° C. for 100 hours to hydrolyze triethyl phosphate and salt. Exchange reaction was performed to obtain a methanol solution of ethyldimethylammonium diethylphosphate monoanion. The above solution was heated at a reduced pressure of 1.0 kPa or less at 50 ° C. until the distillation of methanol disappeared, and after the methanol was distilled off, the temperature was raised from 50 ° C. to 100 ° C. and heated for 30 minutes to volatilize components. Was distilled off to obtain an electrolyte (E-5) {ethyldimethylammonium diethylphosphate monoanion}.

<Example 1>
The electrolyte solution of the present invention was obtained by dissolving 10.0 g of the electrolyte (C-1) in 90.0 g of γ-butyrolactone (A-1). The water content was 0.5%.

<Example 2>
12.0 g of the electrolyte (C-3) was dissolved in 38.0 g of γ-butyrolactone (A-1) and 50.0 g of sulfolane (A-2). Further, 1.5 g of water was added to obtain the electrolytic solution of the present invention.

<Example 3>
1.0 g of electrolyte (C-1) and 5.0 g of electrolyte (E-1) {1,2,3,4-tetramethylimidazolinium diethylphosphate anion} are converted to γ-butyrolactone (A-1 ) The electrolyte solution of the present invention was obtained by dissolving in 94.0 g. The water content was 0.5%.

<Example 4>
3.2 g of electrolyte (C-2) and 8.8 g of electrolyte (E-2) {1,2,3,4-tetramethylimidazolinium dibutyl phosphate anion} are converted to γ-butyrolactone (A-1) It was dissolved in 38.0 g and sulfolane 50.0 g (A-2). Further, 1.5 g of water was added to obtain the electrolytic solution of the present invention.

<Example 5>
7.5 g of electrolyte (E-1) {1,2,3,4-tetramethylimidazolinium diethylphosphate anion} was added to 30.5 g of γ-butyrolactone (A-1) and 61.0 g of sulfolane (A -2). Further, 1.0 g of boric acid and 1.5 g of water were added to obtain the electrolytic solution of the present invention. In addition, it confirmed that the boric acid and electrolyte (E-1) carried out cation exchange and the 1,2,3,4-tetramethyl imidazolinium and borate anion (C-1) were producing | generating. All of the added boric acid becomes 1,2,3,4-tetramethylimidazolinium borate anion (C-1), and 3.4 g (C-1) exists.

<Example 6>
10.0 g of electrolyte (E-3) {triethylammonium diethyl phosphate monoanion} was dissolved in 35.0 g of γ-butyrolactone (A-1) and 52.5 g of sulfolane (A-2). Further, 1.0 g of boric acid and 1.5 g of water were added to obtain the electrolytic solution of the present invention. In addition, it confirmed that the boric acid and electrolyte (E-3) carried out cation exchange, and the triethylammonium borate anion (C-3) was producing | generating. All of the added boric acid becomes triethylammonium borate anion (C-3), and 2.9 g (C-3) is present.

<Example 7>
2.9 g of electrolyte (C-3) and 11.1 g of electrolyte (E-4) {triethylammonium dibutyl phosphate monoanion} 34.0 g of γ-butyrolactone (A-1) and 51.0 g of sulfolane (A -2). Further, 1.5 g of water was added to obtain the electrolytic solution of the present invention.

<Example 8>
2.5 g of electrolyte (C-4) and 10.0 g of electrolyte (E-5) {ethyldimethylammonium / diethyl phosphate monoanion} are mixed with 35.0 g of γ-butyrolactone (A-1) and 52.5 g of sulfolane. Dissolved in (A-2). Further, 1.5 g of water was added to obtain the electrolytic solution of the present invention.

<Example 9>
3.2 g of electrolyte (C-3) and 6 g of electrolyte {triethylamine / adipic acid} were dissolved in 47.0 g of γ-butyrolactone (A-1) and 47.0 g of sulfolane (A-2).
Further, 5 g of water was added to obtain an electrolytic solution of Example 9.

<Comparative Example 1>
The electrolytic solution of Comparative Example 1 was obtained by dissolving 10.0 g of the electrolyte (C-1) in 90.0 g of ethylene glycol. The water content was 0.5%.

<Comparative example 2>
12.0 g of the electrolyte (C-3) was dissolved in 90.0 g of ethylene glycol. Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 2.

<Comparative Example 3>
5.0 g of electrolyte (E-1) {1,2,3,4-tetramethylimidazolinium · diethyl phosphate anion} is dissolved in γ-butyrolactone 94.0 to obtain an electrolytic solution of Comparative Example 3. It was. The water content was 0.5%.

<Comparative example 4>
8.8 g of electrolyte (E-2) {1,2,3,4-tetramethylimidazolinium / phosphoric dibutyl ester anion} was added to 38.0 g of γ-butyrolactone (A-1) and 50.0 g of sulfolane (A -2). Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 4.

<Comparative Example 5>
7.5 g of electrolyte {1,2,3,4-tetramethylimidazolinium phosphate diethyl ester anion} (E-1) was dissolved in 30.5 g of γ-butyrolactone and 61.0 g of sulfolane. Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 5.

<Comparative Example 6>
10.0 g of electrolyte (E-3) {triethylammonium diethyl phosphate monoanion} was dissolved in 35.0 g of γ-butyrolactone (A-1) and 52.5 g of sulfolane (A-2). Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 6.

<Comparative Example 7>
11.1 g of electrolyte (E-4) {triethylammonium dibutyl phosphate monoanion} was dissolved in 34.0 g of γ-butyrolactone (A-1) and 51.0 g of sulfolane (A-2). Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 7.

<Comparative Example 8>
10.0 g of electrolyte (E-5) {ethyldimethylammonium diethylphosphate monoanion} was dissolved in 35.0 g of γ-butyrolactone (A-1) and 52.5 g of sulfolane (A-2). Further, 1.5 g of water was added to obtain an electrolytic solution of Comparative Example 8.

<Comparative Example 9>
6 g of the electrolyte {triethylamine / adipic acid} was dissolved in 47.0 g of γ-butyrolactone (A-1) and 47.0 g of sulfolane (A-2), and 5 g of water was added to obtain an electrolytic solution of Comparative Example 9.

<Comparative Example 10>
5 g of electrolyte {ammonium / adipic acid} was dissolved in 95 g of ethylene glycol, and 2 g of boric acid was further added to obtain an electrolytic solution of Comparative Example 10.

<Comparative Example 11>
5 g of the electrolyte {1,2,3,4-tetramethylimidazolinium / glycolatooxalatoborate anion} was dissolved in 95 g of γ-butyrolactone, and 1.5 g of water was further added to obtain an electrolytic solution of Comparative Example 11. It was.

  Using the electrolytic solutions obtained in Examples 1 to 9 and Comparative Examples 1 to 11, spark voltage and specific conductivity were measured by the following methods and listed in Table 1.

Spark voltage: A 10 cm ² chemical conversion etching aluminum foil for high voltage was used for the anode and a 10 cm ² plain aluminum foil was used for the cathode, and the spark voltage of the electrolyte was measured at 25 ° C when a constant current method (2 mA) was applied. .

Specific conductivity: Specific conductivity at 30 ° C. was measured using a conductivity meter CM-40S manufactured by Toa Denpa Kogyo Co., Ltd.

  As is clear from Tables 1 and 2, in the electrolytes of the present invention (Examples 1 to 9), the specific conductivity of the electrolyte at 30 ° C. was high, and the spark voltage could be increased.

By using the electrolytic solution of the present invention, it is possible to provide an electrolytic solution for electrolytic capacitors that has both high electrical conductivity and high spark voltage, and an electrolytic capacitor using the electrolytic solution. Therefore, the market value of the electrolytic solution of the present invention is very large as the withstand voltage of the power source used in the market is increasing.

Claims (9)

An electrolytic solution for an aluminum electrolytic capacitor containing an electrolyte (C) comprising a borate anion represented by the general formula (1) and an ammonium cation (B) in an aprotic solvent (A).

The electrolytic solution according to claim 1, wherein the product of the acceptor number and the donor number of the aprotic solvent (A) is 500 or less. The electrolyte solution according to claim 1 or 2, wherein the solubility parameter of the aprotic solvent (A) is 10 to 20. The electrolytic solution according to any one of claims 1 to 3, wherein the aprotic solvent (A) is at least one selected from the group consisting of γ-butyrolactone and sulfolane. The electrolytic solution according to any one of claims 1 to 4, wherein the ammonium cation (B) is an amidinium cation. The electrolytic solution according to claim 1, wherein the ammonium cation (B) is a tertiary ammonium cation. The electrolyte solution according to any one of claims 1 to 6, comprising 1 to 10% by weight of the electrolyte (C) based on the total weight of the electrolyte (C) and the aprotic solvent (A). The electrolyte solution of any one of Claims 1-7 containing electrolyte (C) which consists of electrolyte (C) and phosphate ester anion and ammonium cation (B) as electrolyte. An aluminum electrolytic capacitor using the electrolytic solution according to claim 1.