JPS61163621A - Electrolytic liquid for driving electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrolytic solution for driving electrolytic capacitors, and in particular, an electrolytic solution for use in medium and high voltage applications that can reduce the internal resistance of electrolytic capacitors and expand the operating temperature range. Regarding electrolyte.

[Conventional technology]

In various electronic devices such as communication equipment and measurement equipment, the electrical characteristics and life characteristics of electrolytic capacitors are greatly affected by their accuracy and reliability, and especially for smoothing electrolytic capacitors used in switching regulators with high switching frequencies. , it is required to have low impedance characteristics against high frequencies and an upper limit operating temperature exceeding 105°C. In general, dry electrolytic capacitors are produced by impregnating an electrolytic capacitor element with an electrolytic solution, which is wound by overlapping electrode foils on the anode and cathode sides with a separator paper interposed between the two. It is enclosed in. Therefore, the electrical characteristics of an electrolytic capacitor are determined by the electrode foils and cells that constitute the electrolytic capacitor element.
9 The electrical or chemical properties of the electrolytic solution impregnated into the electrolytic capacitor element, such as the specific resistance and spark voltage, are greatly affected by the operating temperature range and impedance characteristics of the electrolytic capacitor. It is known that

Conventionally, the so-called ethylene glycol-boric acid electrolyte, which is made by dissolving boric acid or its ammonium salt in a solvent mainly composed of ethylene glycol, has been used as the electrolyte for medium-high voltage electrolytic capacitors with a rated voltage exceeding 160 (V). .

[Problem that the invention seeks to solve]

However, this type of electrolytic solution has a particularly high specific resistance compared to a low-pressure electrolytic solution, which causes an increase in loss in the electrolytic capacitor as well as heat generation, which has the disadvantage of accelerating thermal deterioration of the electrolytic capacitor. Further, this type of electrolytic solution contains a large amount of water produced by the esterification reaction between ethylene glycol and boric acid in addition to the water contained in its constituent chemicals.

That is, in the case of this type of electrolytic solution, the ester reaction easily proceeds to produce 3 mol of water from 1 mol of boric acid, and the water content in the electrolytic solution becomes extremely large. Therefore, this moisture significantly deteriorates the dielectric oxide film formed on the surface of the electrode foil on the anode side, making it difficult to maintain stable electrical characteristics of the electrolytic capacitor for a long period of time. Moreover, such moisture generates a large amount of water vapor at high temperatures exceeding 100°C, causing an abnormal increase in the internal pressure of the outer case, causing expansion of the explosion-proof valve, deformation of the external appearance of the outer case, and associated electrical characteristics. This may cause deterioration, etc. For this reason, this type of electrolytic solution cannot be used at high temperatures exceeding 105° C., which imposes restrictions on the upper limit operating temperature of electrolytic capacitors.

[Means for solving problems]

An object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor, which is suitable for medium and high voltage electrolytic capacitors, by reducing the specific resistance value, reducing the water content, and improving heat resistance.

As a result of extensive studies, the present inventors have found that this purpose is to use a quaternary ammonium ion as a cation component and an alkyl, aryl, /#-fluoroalkyl-substituted aryl or heterocyclide ion of boron as an anion. It has been found that this can be achieved by using an electrolytic solution prepared by dissolving an ammonium salt as a component in an organic solvent.

That is, the present invention relates to an electrolytic solution for driving an electrolytic capacitor, which is characterized by dissolving an ammonium salt represented by the following general formula in an organic solvent.

[However, in the formula, R, R, R and R are an alkyl group having 1 to 16 carbon atoms, and an aryl group having 6 to 10 carbon atoms.
It is the basis. R' t R'*R' and R8 are an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and a fluoroalkyl-substituted aryl group having 7 to 10 carbon atoms. ) group or a heterocyclic residue. ] Since the ammonium salt of the present invention is dissolved in an organic solvent and the driving electrolyte does not produce water due to an esterification reaction as observed in conventional ethylene glycol-boric acid electrolytes, it does not form a dielectric oxide film. The deterioration of the electrolytic capacitor can be significantly suppressed, and the electrical characteristics of the electrolytic capacitor can be maintained stably for a long period of time. In addition, the driving electrolyte of the present invention has a lower resistivity than conventional ethylene glycol-boric acid electrolytes, and the electrolyte itself has good thermal stability.
Thermal deterioration of electrolytic capacitors can be slowed down.

The ammonium salt used in the driving electrolyte of the present invention is
As represented by the above general formula, the cation component is an ammonium salt consisting of a quaternary ammonium ion and the anion component is an alkyl, aryl, .g-fluoroalkyl-substituted aryl or heterocyclide ion of boron. .

Specific examples of cationic components include tetramethylammonium, tetraethylammonium, tetrabutylammonium, tetraamylammonium, trimethylglobylammonium, trimethylbutylammonium, trimethylhexylammonium, trimethyloxylammonium, trimethylisobutylammonium, and trimethylturkyalybutylammonium. , trimethylisobutylammonium, trimethylinobutylammonium, trimethylhexadecylammonium, trimethylbutylammonium, trimethylphenylammonium, triethylbutylammonium, triethylphenylammonium, triethylmethylammonium, triethylhexylammonium, triethylphenylammonium, superliglopyrubutylammonium , tributylmethylammonium, tributylethylammonium, nobropyl diethylammonium, dibutyldiethylammonium, dibutylmethylammonium, somethylnophenylammonium, diethyldiphenylammonium, dibutylethylmethylammonium, dibutylethylmethylammonium, butylpropylethylmethylammonium, etc. .

Among these cation components, asymmetric quaternary ammonium salts such as triethylbutylammonium are preferably used because they have good solubility in organic solvents and high electrical conductivity of the electrolytic solution.

Specific examples of anionic components include tetramethylpyrrolyl, nomethylnophenylderate, trimethylphenylpyrrolylvirate, nomethylnopyrrolyl, trimethylphenylborate, trimethylpyrrolylvirate, tetrabutylvirate, and tributylphenylborate. , tetraphenyl plate, tetratolyl plate, tetraperfluorotolyl borate, and the like.

Among these anion components, aryl compounds of boron such as tetraphenyl plate are preferably used because of their good thermal stability.

Specific examples of ammonium salts include triethylbutylammonium tetramethylplate, triethylbutylammonium dimethyldiphenyl C-late, trimethylbutylammoniumtetraphenyl? rate, tetrabutylammonium tetrabutylderate, butylethylmethylammonium triptylphenylgelate, butylnoethylammonium trinotylphenylderate, triethylphenylammonium trimethylhylorylgelate, trimethylphenylammonium triptylphenyldaleate, nomethyl Ptylphenylammonium nomethylnopyrrolyl? Examples include, but are not necessarily limited to, tetrabutylammonium tetratolyl brate, tetrabutylammonium tetratolyl brate, and the like.

These ammonium salts may be used alone or in combination of two or more.

Furthermore, the ammonium salt of the present invention may be used as a mixed electrolyte with an alkali metal salt, such as a lithium salt, a sodium salt, and a potassium salt.

Furthermore, the ammonium salt of the present invention is a pyrylium or bilinium cation represented by the following formula (1): [wherein, X is an oxygen atom or a nitrogen atom, and R' is a hydrogen atom or an alkyl having 1 to 15 carbon atoms] group, carbon number 6-15
aryl group, RI' is /5C11'7
Atom or alkyl group having 1 to 10 carbon atoms, 6 carbon atoms
~15 7aryl groups, m is O when X is an oxygen atom, and 1 when X is a nitrogen atom. n is 0
Or 1-5. ] Or, an imidazolicum cation represented by the following formula (n); [wherein R, R, and R are hydrogen atoms, and the alkyl group having 1 to 15 carbon atoms is an aryl group having 6 to 15 carbon atoms; I/ (1
ryl) group, R, and R are a hydrogen atom, an atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 15 carbon atoms. ] or the following formula (I)
or a cargenium cation represented by (W); or [wherein R, e R2, R, are hydrogen atoms (R1e R2
#R3 is not a hydrogen atom at the same time], an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an aryl group having 6 to 15 carbon atoms, or 10R
6 groups, provided that R6 represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 15 carbon atoms, and R4
is a hydrogen atom, an alkyl group having 1-15 carbon atoms, and 6 carbon atoms.
~15 aryl groups. ] may be used in combination with an electrolyte having as a cationic component.

However, when the ammonium salt of the present invention whose cationic component is a quaternary ammonium ion is mixed with another electrolyte, it is preferable to use the ammonium salt of the present invention in a form containing equal moles or more.

The organic solvent for the electrolyte used in the present invention is not particularly limited, but representative examples include aliphatic and aromatic alcohol compounds, 2) IJ compounds, ethers, esters, ketones, and amides. , carzenates, sulfolane compounds,...rokene compounds, nitro compounds, amines, carboxylic acids, phosphoric acids, acid anhydrides, lactones, etc. The boiling point of these organic solvents is preferably 100°C or higher. Specific examples of preferred organic solvents include formic acid, acetic acid, acetic anhydride,
Methyl cellosolve, cellosolve, ethylene glycol,
diethylene glycol, 1,4-nooxane, noblime, 4-methyl-2-intanone, acetylacetone,
n-butyronitrile, i-butyronitrile, benzonitrile, ethylenenoamine, birinone, formamide, N
-Methylformamide, trimethylformamide, N-methylacetamide, trimethylacetamide, N-methylacetamide, hexamethylphosphoramide, N-methylpyrrolidone, trimethylsulfoxide, sulfolane, 3
-Methyl-sulfolane, N-methylthiopyrrolidone, nitromethane, nitrobenzene, propylene/carzenate, ethylene carbonate, propylene glycol, Nogrogirenda IJ ml-, triethyl phosphate, trimethyl phosphate, anisole, O-+ m-r p- Examples include tolnitrile and r-butyrolactone.

The concentration of the ammonium salt in the electrolytic solution of the present invention varies depending on the required specific resistance value of the electrolytic solution, so it cannot be unconditionally defined, but it is usually preferably 1 mol/1 or more.

Further, the specific resistance value of the electrolytic solution of the present invention is preferably 10'Ω·F or less.

〔Effect of the invention〕

In the ammonium salt of the present invention, the anion component is BM@a-
Boron alkyl, aryl-, such as
B-fluoroalkyl-substituted aryl or heterocyclide ion, perchlorate ion, B
Halodanides of group 1lla elements such as F4-, PF6
It has superior thermal and electrical stability compared to ammonium salts having a halide of a Va group element such as - as an anion component.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 to 2 and Comparative Examples An electrolytic solution was prepared by mixing an organic solvent and the ammonium salt of the present invention in the proportions shown in Table 1.

Table 1 shows the water content and specific resistance value at 25° C. of the obtained electrolytic solution.

In addition, in order to confirm the effect of an ammonium salt in which the anion component in the electrolytic solution of the present invention is an alkyl, aryl, /#-fluoroalkyl-substituted aryl or heterocyclide ion of boron, K was used as a comparative example. The water content and specific resistance values were similarly measured for an electrolytic solution consisting of an ammonium salt whose anion component is a halide ion of the MA group, and for a conventional ethylene glycol-boric acid electrolytic solution mainly composed of ethylene glycol. I did it. The results are also shown in Table 1.

Table 1 Next, the electrical characteristics of an electrolytic capacitor using the electrolytic solution according to the present invention will be explained in comparison with an electrolytic solution of a comparative example and an electrolytic capacitor using a conventional electrolytic solution. The sample electrolytic capacitor was made by etching the surface of high-purity aluminum foil and then anodizing it by applying a voltage of 620 (V) to form a dielectric oxide film.
The aluminum foil subjected to only etching treatment was used as a cathode side electrode, and a separator paper was interposed between these two electrodes and wound to form an electrolytic capacitor element. This electrolyte and a conventional electrolyte are separately impregnated and housed in an outer case, and the opening of the outer case is sealed with an elastic sealing member. Each sample electrolytic capacitor has a rated voltage of 400 (V
), the rated capacitance is 10 (μF). Table 2 is 20
It shows the initial characteristics of each sample electrolytic capacitor under ℃.

Table 2 Note) This equivalent series resistance Table 3 is based on the load life test of each sample electrolytic capacitor mentioned above (showing the characteristics over 2000 hours. The load life test was conducted at a rated voltage of 400 at a high temperature of 120°C. (V) was applied to each sample electrolytic capacitor and left for 2000 hours. After this test time, the same measurements as the initial characteristics were performed.
Also, be careful to observe changes in the external shape of the outer case.

Table 3 Note) *Percentage of 20 sample capacitors that caused deformation in the appearance of the outer case As explained above, according to the present invention, an electrolytic solution with a small resistivity value and a low water content can be obtained. It is possible to expand the operating temperature range with low loss, especially by increasing the upper limit operating temperature.
It is possible to construct an electrolytic capacitor with low impedance characteristics and high withstand voltage.Moreover, since the water content is small, the internal pressure of the exterior case does not increase abnormally due to the generation of water vapor under high temperatures, and the dielectric of the electrode foil on the anode side It does not deteriorate the body's oxidized film. In particular, an electrolytic capacitor using the electrolyte of the present invention has excellent thermal stability.

For example, in Table 2, there is not much difference in the capacitor characteristics between Examples 1 and 2 and the comparative example;
In the load life test shown in the table, it can be seen that Examples 1 and 2 clearly exhibit better characteristics than the Comparative Examples. The reason for this is thought to be that not only the water content of the electrolytic solution of the present invention is low, but also that the electrolyte of the present invention itself has good thermal stability.

Claims (1)

[Scope of Claims] An electrolytic solution for driving an electrolytic capacitor, characterized in that an ammonium salt represented by the following general formula is dissolved in an organic solvent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [However, in the formula, R^1, R^2, R^3, and R^4 are alkyl groups having 1 to 16 carbon atoms, or 6 to 10 carbon atoms.
is an aryl group. R^5, R^6, R
^7 and R^8 are an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 15 carbon atoms, and 7 carbon atoms.
~10 perfluoroalkyl substituted aryl
) group or a heterocyclic residue. ]