JP2002093665A - Electrolytic solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic solution whose electrical conductivity is high, whose volatility is low and which hardly corrodes and degrades a material forming an electrochemical element. SOLUTION: The electrolytic capacitor is composed of a salt solution, in which a compound expressed by chemical formula 5 is used as a cation component. In the chemical formula, R1 to R6 independently represent a 1 to 5C alkyl group, R7 and R8 independently represent hydrogen atoms or a 1t o 5C alkyl group, and n represents an integer of 1 to 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution used for an electrolytic capacitor, an electric double layer capacitor, a secondary battery, an electronic display device and the like.

[0002]

2. Description of the Related Art As a conventional electrolytic solution, particularly an electrolytic solution for electrolytic capacitors and the like, Japanese Patent Application Laid-Open No. 54-7564 discloses an electrolytic solution using an amine salt of maleic acid.
No. 9856 discloses 1,8-diazabicyclo [5,4,
0] An electrolyte using a salt of a diazabicycloalkene such as undecene-7, and Japanese Patent Publication No. 3-8092 discloses an electrolyte using a quaternary ammonium salt of an aromatic carboxylic acid.

[0003]

However, as the impedance of electrolytic capacitors and the like has been reduced, a high-conductivity electrolytic solution has been required, and an amine salt of maleic acid as disclosed in JP-A-54-7564 is known. Alternatively, when a salt of a diazabicycloalkene such as 1,8-diazabicyclo [5,4,0] undecene-7 as an electrolyte as disclosed in Japanese Patent Publication No. 3-79856 is used as an electrolyte, the specific conductivity is not sufficient. It is enough. On the other hand, a quaternary ammonium salt of an aromatic carboxylic acid as disclosed in Japanese Patent Publication No. 3-8092 has a relatively high specific conductivity but is still insufficient, and is a material for forming an electrochemical element. There are problems such as causing corrosion and deterioration of the steel.

The present invention has been made in view of the above problems, and has as its object to cause corrosion and deterioration of a material forming an electrochemical element having a high specific conductivity and a low volatility. It is to provide a difficult electrolyte.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, a solution using a salt having a compound represented by the following formula 3 as a cation component as an electrolyte is obtained. The present invention has been found to have high conductivity and to prevent corrosion and deterioration of the material forming the electrochemical element, thereby completing the present invention.

That is, the present invention is an electrolyte comprising a salt solution containing a compound represented by the following formula 3 as a cation component.

[0007]

Embedded image

(Wherein, R _{1 to} R ₆ each independently have 1 carbon atom)
To 5 alkyl groups, R ₇ and R ₈ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
Is an integer. Hereinafter, the present invention will be described in detail.

The electrolyte referred to in the present invention refers to a salt comprising a cation component represented by the above formula (3) and an anion serving as a counter ion component thereof.

Here, the cation component of the compound used in the electrolytic solution of the present invention is a compound represented by Chemical Formula 3, wherein R _{1 to} R ₆ are each independently a C 1-5 carbon atom. R ₇ and R ₈ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. 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, and a t-butyl group. N is an integer of 1 to 20. For example,
Hexaalkylalkylenediammonium compounds represented by the following formula 4 are exemplified.

[0011]

Embedded image

(Wherein R _{9 to} R ₁₂ are a methyl group or an ethyl group, and n is an integer of 1 to 20.) Specifically, N, N, N, N ′, N ′, N '-Hexamethyldodecamethylenediammonium, N, N, N,
N ′, N ′, N′-hexamethyloctamethylenediammonium, N, N, N, N ′, N ′, N′-hexamethylhexamethylenediammonium, N, N, N, N ′,
N ′, N′-hexamethyltetramethylenediammonium, N, N, N, N ′, N ′, N′-hexamethylpropylenediammonium, N, N, N, N ′, N ′, N ′
-Hexamethylethylenediammonium, N, N'-dimethyl-N, N, N ', N'-tetraethylhexamethylenediammonium.

Such a compound having two quaternary ammonium ions in an aliphatic hydrocarbon is more excellent in conductivity than a conventional compound having one quaternary ammonium ion, and has low volatility and electric conductivity. It has the feature that the corrosion and deterioration of the material forming the chemical element are small.

In the electrolytic solution of the present invention, as a counter ion component for the compound represented by the chemical formula 3, those generally used in the electrolytic solution can be applied, but they are generated when used as the electrolytic solution. Anions that are stable to heat and have high conductivity are preferred. Specifically, aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, and benzoic acid Aromatics such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, salicylic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cytocholanic acid, dimethylmaleic acid, nitrobenzoic acid, nitrophthalic acid, and hydroxybenzoic acid Carboxylic acid, other, thiopropionic acid, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearyl acid, acrylic acid, methacrylic acid , Carboxylic acids such as oleic acid, cinnamic acid, phenol,
Phenols such as cresol, catechol and cyclohexylphenol, and anions such as p-toluenesulfonic acid, phosphoric acid, boric acid, chloride, fluoride, bromide, iodide and perchloric acid, among which benzoic acid , Phthalic acid, trimellitic acid, succinic acid, adipic acid, maleic acid and fumaric acid are preferred because of their high conductivity and high stability. These anionic components may be used alone or in combination of two or more.

The method for producing the cation component of the present invention is carried out by alkyl quaternary salification of an alkylated alkylenediamine which is a tertiary amine, wherein alkylation is carried out by using an alkyl halide, and dialkyl carbonate is used. However, in the method using an alkyl halide, a method using a carbonic acid diester is preferable because a metal halide may be mixed into a product. For example, it is manufactured by reacting N, N, N ', N'-tetraalkylalkylenediamine with dimethyl carbonate to form a quaternary salt, and then adding an acid to exchange the counter anion with carbonate.

The molar ratio of the cation component to the anion component of the electrolyte of the present invention is not particularly limited, but usually a salt is formed in the form of 1 mole of cation to 1 mole of anion.

As the solvent used in the electrolytic solution of the present invention, those generally used in the electrolytic solution can be applied. The solvent can dissolve the above-mentioned electrolyte and can generate heat when used as the electrolytic solution. Solvents which are stable and have high conductivity are preferred. Specifically, alcohols such as butyl alcohol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin; ethers such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether; N, N-dimethylformamide; Amides such as N, N-diethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone,
Methyl oxazolidin-2-one, dimethyl sulfoxide, γ-butyrolactone, dimethyl carbonate and the like. Among them, γ which has high conductivity and is thermally stable
-Butyrolactone, ethylene glycol, 1,3-dimethylimidazolidinone, 3-methyloxazolidine-2
-On is preferably used. These solvents may be used alone or as a mixture of two or more. Although the solvent used in the present invention can be used in an anhydrous state, water of 1 to 10% by weight can be added for the purpose of improving electric conductivity.

The amount of the electrolyte of the present invention dissolved in the above solvent is not particularly limited, but is not more than the saturation concentration, preferably in the range of 5 to 50% by weight. If it is less than 5% by weight, sufficient conductivity may not be obtained.

The electrolytic solution of the present invention consists essentially of the electrolyte of the present invention and a solvent. For the purpose of preventing corrosion, reducing leakage current, absorbing hydrogen gas, etc., various auxiliary solutes such as phosphoric acid derivatives , A nitrobenzene derivative or the like can be added.

The electrolytic solution of the present invention has a high specific conductivity as described above, and is unlikely to corrode or deteriorate the material forming the electrochemical element. Therefore, the electrolytic solution, the electric double layer capacitor, the secondary battery, It can be used for a mic display element and the like.

[0021]

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The abbreviations shown below represent the following compounds.

MR-DM • PA: (N, N, N,
N ', N', N'-hexamethylhexamethylenediammonium) -phthalate MR-DM.BA: (N, N, N, N ', N', N '
-Hexamethylhexamethylenediammonium) -benzoate MR-DM.MA: (N, N, N, N ', N', N '
-Hexamethylhexamethylenediammonium) -maleate TE-DM.PA: (N, N, N, N ', N', N '
-Hexamethylethylenediammonium) -phthalate TP-DM.PA: (N, N, N, N ', N', N '
-Hexamethylpropylenediammonium) -phthalate TEA.MA: triethylamine-maleate TEA.PA: triethylamine-phthalate DBU.MA: (1,8-diazabicyclo [5,
4,0] undecene-7) -maleate DBU · PA: (1,8-diazabicyclo [5,
4,0] undecene-7) -phthalate TEA-M.PA: triethylmethylammonium-
Phthalate TEA-E.PA: Tetraethylammonium-phthalate Example 1 172 g (1.0 mol) of N, N, N ', N'-tetramethylhexamethylenediamine, 198 g of dimethyl carbonate in a 1 L stirred autoclave. (2.2 mol), 200 g of methanol was charged as a solvent, and reacted at a reaction temperature of 110 ° C. for 12 hours. Thereafter, unreacted dimethyl carbonate and methanol were distilled off, and N, N, N, N ′, N ′, N ′, N'-hexamethylhexamethylenediammonium carbonate
27 g (87% yield) were obtained. Next, 50 g of the obtained quaternary carbonate was placed in a 1 L flask equipped with a stirrer and a dropping funnel.
(0.19 mol) was dissolved in 200 g of methanol and charged, and 63 g (0.38 mol) of phthalic acid, also dissolved in 300 g of methanol, was gradually dropped from the dropping funnel, whereby carbon dioxide gas was generated. After completion of the dropwise addition, the methanol was removed to remove N, N, N, N ', N', N'-hexamethylhexamethylenediammonium-phthalate 100 g.
(99% yield).

Examples 2 to 4 The salts of Examples 2 to 3 were obtained in the same manner as in Example 1 except that phthalic acid was replaced with benzoic acid and maleic acid, respectively.

Examples 4, 5 N, N, N ', N'-tetramethylhexamethylenediamine was converted to N, N, N', N'-tetramethylethylenediamine, N, N, N ', N'-tetramethyldiamine. The salts of Examples 5 and 6 were obtained in the same manner as in Example 1 except that methylpropylenediamine was used.

Table 1 shows the ratio at room temperature when 2.5 g of each of the compounds of Examples 1 to 5 of the present invention and Comparative Example 1 to 6 of a conventional compound for an electrolytic solution were dissolved in 7.5 g of γ-butyrolactone. Indicates conductivity.

[0027]

[Table 1]

[0028]

The electrolytic solution of the present invention has high conductivity and low volatility, and is hardly corroded or deteriorated for a material forming an electrochemical element, and is industrially useful.

Claims (3)

[Claims] 1. An electrolytic solution comprising a salt solution containing compound A represented by the following formula 1 as a cation component. Embedded image (Wherein, R _{1 to} R ₆ each independently represent an alkyl group having 1 to 5 carbon atoms; R ₇ and R ₈ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; It is an integer of -20.) 2. The electrolytic solution according to claim 1, wherein the compound A is a hexaalkylalkylenediammonium ion represented by the following chemical formula 2. Embedded image (In the formula, R9 to R12 are a methyl group or an ethyl group, and n is an integer of 1 to 20.) 3. The method according to claim 1, wherein the anion of the salt having the compound A represented by the formula 1 or 2 as a cation component is an anion component of an organic acid or an inorganic acid. 3. The electrolytic solution according to 2.