KR20020029961A - A preparation method for electrolyte for aluminum electrolytic capacitor for low pressure - Google Patents

Abstract

PURPOSE: An electrolyte for aluminum electrolytic capacitor and method for producing electrolyte is provided to achieve an improved loss angle characteristics and equivalent series resistance by improving conductivity and sparking voltage. CONSTITUTION: An electrolyte is composed of a solvent consisting of gamma-butyrolactone 50 to 98.1 weight percent; and a solute consisting of a mixture 1.9 to 50 weight percent, wherein the mixture is obtained by mixing imidasol as a cation and maleic acid and phthalic acid as an anion. The weight ratio between the maleic acid and imidasol, and phthalic acid and imidasol is 90:10 to 20:80. The imidasol has a chemical formula, wherein R¬1 is hydrocarbon group or cyan group of C1 to C10 or cyano-alkyl group of C1 to C5, and R¬2 is hydrocarbon group of C1 to C10.

Description

Electrolytic solution of low pressure aluminum electrolytic capacitors and a method of manufacturing the same

The present invention relates to an electrolyte used in a low pressure aluminum electrolytic capacitor and a method for manufacturing the same. More specifically, a low pressure aluminum electrolytic capacitor having both reduced loss angle and equivalent DC resistance (hereinafter, referred to as 'ESR') characteristics during commercialization. It relates to an electrolyte solution and a method for producing the same.

Generally, aluminum electrolytic capacitors are classified into low pressure (below 160WV), medium pressure (160 ~ 400WV), and high pressure (more than 400WV), and the criteria of this classification are generally determined by the electrolyte loaded into the electrolytic capacitor. .

Examples of the electrolyte used for the low pressure aluminum electrolytic capacitors having a rated voltage of 160 WV or less among the electrolytes classified as above include a solvent consisting of 70-90 wt% of γ-butyrolactone (GBL) and 5.5 wt% of water, 1.9 The electrolyte solution comprised from the additive which consists of 1 type of solute chosen from -20 weight% adipic acid and maleic acid, and 0.1 to 3 weight% triton X is mentioned. In this way, an electrolyte solution using a γ-butyrolactone solvent is prepared by adding a solvent and a solute, followed by stirring.

This leads to triethylammonium salt of maleic acid, tetraethylammonium salt, and triethylammonium salt of phthalic acid, which are present in electrolytes to satisfy thermal stability, high conductivity, chemical resistance, and the like, which are disclosed in US Pat. No. 5,870,275. Imidazole salts of maleic acid having an amidine group are commercially available.

In this case, however, the conductivity is improved, but the SPV value is relatively decreased. That is, the use of an additive capable of increasing pressure, such as Triton X, is used. The problem of falling.

The present inventors have not only solved this problem, but also conducted the research and experiment to propose the present invention in order to enable the production of the electrolyte solution at a lower temperature, thereby improving productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrolyte solution for a low pressure aluminum electrolytic capacitor which can lower the equivalent DC resistance (ESR) characteristics during commercialization by appropriately controlling the composition of components added during the preparation of an electrolyte solution, thereby increasing both conductivity and SPV of the electrolyte solution. have.

Another object of the present invention is to provide a method for producing an electrolyte solution of a low pressure aluminum electrolytic capacitor that can improve the productivity by lowering the manufacturing temperature.

According to one aspect of the invention,

solvent of 50-98.1% by weight of γ-butyrolactone; And

Formula 1 as the cation

(Wherein R ¹ is a C ₁ -C ₁₀ hydrocarbon or cyan group, C ₁ -C ₅ cyanoalkyl group, and R ² is a C ₁ -C ₁₀ hydrocarbon group)

A solute made up of 1.9-50% by weight of a mixture of maleic acid and phthalic acid as an anionazole salt having an anion;

The weight ratio of the imidazole salt of maleic acid and the imidazole salt of phthalic acid is 90: 10-20: 80, The electrolyte solution of the low pressure aluminum electrolytic capacitor is provided here.

According to the second aspect of the present invention,

solvent of 50-98.1% by weight of γ-butyrolactone; And

Formula 1 as the cation

[Formula 1]

(Wherein R ¹ is a C ₁ -C ₁₀ hydrocarbon or cyan group, C ₁ -C ₅ cyanoalkyl group, and R ² is a C ₁ -C ₁₀ hydrocarbon group)

A solute made up of 1.9-50% by weight of a mixture of maleic acid and phthalic acid as an anionazole salt having an anion;

Wherein the weight ratio of the imidazole salt of maleic acid to the imidazole salt of phthalic acid is 90:10 to 20:80, and the low pressure aluminum capacitor is characterized in that the electrolytic solution of the low pressure aluminum electrolytic capacitor is stirred at room temperature for 60 to 120 minutes. A method for producing an electrolyte solution is provided.

Hereinafter, the present invention will be described in detail.

The present invention relates to an electrolytic solution composed of γ-butyrolactone (solvent), imidazole salt, and a mixture (solute) of maleic acid and phthalic acid. The reason for limitation on these contents will be described below.

The γ-butyrolactone plays a role of dissolving the electrolyte and influencing the characteristics. If the content is less than 50% by weight, precipitation occurs due to a decrease in solubility, and when the content exceeds 98.1% by weight, the specific resistance is increased. Poor reliability Therefore, in the present invention, it is preferable to limit the content of γ-butyrolactone to 50 to 98.1% by weight.

The imidazole salt, maleic acid, and phthalic acid each play a role of a cation and an anion as the main electrolyte, and an imidazole salt having the following formula is preferable as the cation, and maleic acid and phthalic acid may be used as the anion.

[Formula 1]

(Wherein R ¹ is a C ₁ -C ₁₀ hydrocarbon or cyan group, C ₁ -C ₅ cyanoalkyl group, and R ² is a C ₁ -C ₁₀ hydrocarbon group)

More preferred cations include 1-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanomethylimidazole, 1-cyanoethylimidazole, 1- Cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole-trimelitate, 1-cyanoethyl 2-ethyl-4-methylimidazole- trimellitate etc. are mentioned.

When the solute content of the cation and the anion is less than 1.9% by weight, the specific resistance is lowered, and when the solute content exceeds 50% by weight, the withstand voltage is lowered and precipitation occurs due to a decrease in solubility. Therefore, in the present invention, it is preferable to limit the solute content to 1.9 to 50% by weight.

In addition, the mixing ratio of the imidazole salt of maleic acid and the imidazole salt of phthalic acid is 90:10 to 20:80, more preferably 60:40 to 40:60, in terms of weight ratio. It is preferable from the viewpoint of improving conductivity.

In addition, the present invention relates to a method for preparing an electrolytic solution having the above content, which will be described in more detail below.

In the present invention, a mixture of imidazole salt having a content as described above with maleic acid and phthalic acid is added to γ-butyrolactone having the above content, followed by stirring at room temperature for 60 to 120 minutes.

At this time, if the stirring time is less than 60 minutes, dissolution is not performed completely, the characteristic value is not properly exhibited, and if the stirring time exceeds 120 minutes, there is a problem that the specific resistance increases, which is not preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

To γ-butyrolactone, a solute having a 55:45 weight ratio of 1-methylimidazole salt of maleic acid and 1-methylimidazole salt of phthalic acid was added and stirred at room temperature for 90 minutes to prepare an electrolyte solution. In addition, a commercially available electrolyte solution consisting of 1-methylimidazole salt of γ-butyrolactone maleic acid and other additives and an electrolyte solution consisting of 1-methylimidazole salt of phthalic acid and other additives were obtained, and these were converted into conventional examples 1 and 2, respectively. It was.

Further, for comparison, an electrolyte solution in which 1-methylimidazole salt of maleic acid was added to γ-butyrolactone was shown as Comparative Example 1, and an electrolyte solution in which 1-methylimidazole salt of phthalic acid was added as Comparative Example 2.

The addition amount was as shown in Table 1, and the specific resistance (저항 · cm / 25 ℃), withstand voltage, pH of the prepared electrolyte was measured and shown in Table 1 below.

In Table 1, γ-butyrolactone is expressed as 'GBL', maleic acid as 'MA', phthalic acid as 'PA', and 'IZ' as imidazole salts, and triton-X is octylphenoxy ethylene oxide. It means an additive.

Inventive Example 1 Inventive Example 2 Conventional Example 1 Conventional Example 2 Comparative Example 1 Comparative Example 2 Ingredient composition (%) GBL (% by weight) 75 75 75 75 75 75 MA-IZ (wt%) - - 25 - 25 - PA-IZ (wt%) - - - 25 - 25 MA-IZ / PA-IZ (wt%) 25 25 - - - - Triton-X (% by weight) - - One One - - Electrolyte Characteristics Specific resistance (Ωcm / 25 ℃) 0.0629 0.0654 0.0654 0.0862 0.0667 0.0901 Withstand voltage (V) 52.9 51.2 - - 40.1 65.5 pH 7.5 7.5 7.2 7.5 7.5 8.0

As can be seen in Table 1, the invention examples (1,2) satisfying the conditions of the present invention is characterized by high electrolyte solution, whereas Comparative Example (1,2) has a similar composition to the present invention, but Since each of the mixtures of maleic acid and phthalic acid was used, the electrolyte properties were all inferior.

Therefore, in the present embodiment, it was confirmed that it is preferable to use a mixture of GBL, maleic acid-imidazole salt, and phthalic acid-imidazole salt.

Example 2

In the present embodiment, an appropriate mixing ratio of GBL, maleic acid-imidazole salt and phthalic acid-imidazole salt is determined. Electrolyte was added to the content ratio of the imidazole salt of (gamma) -butyrolactone, maleic acid, and the imidazole salt of phthalic acid shown in the following table | surface, and it stirred for 90 minutes at room temperature, and prepared electrolyte solution.

The specific resistance (Ω · cm / 25 ° C.), breakdown voltage, and pH of the prepared electrolyte were measured and shown in Table 2 below.

Inventive Example 3 Inventive Example 4 Inventive Example 5 Inventive Example 6 Inventive Example 7 Composition GBL (% by weight) 98.1 90 75 60 50 MA-IZ / PA-IZ (wt%) 1.9 10 25 40 50 Electrolyte Characteristics Specific resistance (Ωcm / 25 ℃) 0.6667 0.1135 0.0629 0.0592 0.0515 Withstand voltage (V) 91 70.4 52.9 35.7 24.3 pH 7.1 7.4 7.5 6.94 7.2

As can be seen from the above table, when the content ratio of GBL: solute (electrolyte) is 50:50 (Inventive Example 7), the conductivity may be high, but the withstand voltage characteristics are poor, the solubility is poor, and also the content of GBL: solute (electrolyte) When the ratio was 98.1: 1.9 (Inventive Example 3), the conductivity was too low to be used as a capacitor. Therefore, the proper content ratio of GBL: solute (electrolyte) was found to be 98.1: 1.9-50: 50.

Example 3

In this embodiment, the mixing ratio between MA-IZ and PA-IZ is determined within the proper mixing ratio between GBL and MA-IZ / PA-IZ determined in Example 2.

The same experiment as in Example 2 was added except that GBL and MA-IZ / PA-IZ were added in a 75:25 weight ratio, where the content ratio of MA-IZ / PA-IZ was changed to the amount shown in the following table. Was repeated and the results are shown in Table 3.

Inventive Example 8 Inventive Example 9 Inventive Example 10 Inventive Example 11 Inventive Example 12 Comparative Example 3 Composition GBL (% by weight) 75 75 75 75 75 75 MA-IZ / PA-IZ (wt% (content ratio)) 25 (90:10) 25 (55:45) 25 (50: 5) 25 (40:60) 25 (20:80) 25 (10:90) Electrolyte Characteristics Specific resistance (Ωcm / 25 ℃) 0.0621 0.0629 0.0654 0.0714 0.0862 0.0971 Withstand voltage (V) 36.2 52.9 51.2 49.5 63.5 67.5 pH 7.9 7.5 7.5 7.4 7.4 7.3

As shown in Table 3, when the ratio of MA-IZ and PA-IZ is 10:90 (Comparative Example 3), the characteristic value is lower than that of 1-methylimidazole salt of phthalic acid (Comparative Example 2). In the case where the ratio of MA-IZ and PA-IZ is 90:10 (Inventive Example 8), 1-methylimidazole salt of maleic acid was used (Comparative Example 1) and its characteristics were improved. Since no effect was found, it can be seen that the content ratio of MA-IZ and PA-IZ is preferably in the range of 90:10 to 20:80.

As described above, according to the present invention, by appropriately controlling the composition of the electrolyte used in the low-voltage aluminum electrolytic capacitor having a rated voltage of 160WV or less, the conductivity and withstand voltage are improved, so that the loss angle characteristics and equivalent DC resistance (ESR) during commercialization are improved. There is an effect that the electrolyte of the low-voltage aluminum capacitor is improved.

Claims (4)

solvent of 50-98.1% by weight of γ-butyrolactone; And Formula 1 as the cation [Formula 1] (Wherein R ¹ is a C ₁ -C ₁₀ hydrocarbon or cyan group, C ₁ -C ₅ cyanoalkyl group, and R ² is a C ₁ -C ₁₀ hydrocarbon group), A solute made up of 1.9-50% by weight of a mixture of maleic acid and phthalic acid as an anionazole salt having an anion; Here, the weight ratio of the imidazole salt of maleic acid and the imidazole salt of phthalic acid is 90: 10-20: 80, The electrolyte solution of the low voltage aluminum electrolytic capacitor The electrolyte according to claim 1, wherein the weight ratio of the imidazole salt of maleic acid to the imidazole salt of phthalic acid is 60:40 to 40:60. solvent of 50-98.1% by weight of γ-butyrolactone; And Formula 1 as the cation [Formula 1] (Wherein R ¹ is a C ₁ -C ₁₀ hydrocarbon or cyan group, C ₁ -C ₅ cyanoalkyl group, and R ² is a C ₁ -C ₁₀ hydrocarbon group), A solute made up of 1.9-50% by weight of a mixture of maleic acid and phthalic acid as an anionazole salt having an anion; Wherein the weight ratio of the imidazole salt of maleic acid to the imidazole salt of phthalic acid is 90:10 to 20:80, and the low pressure aluminum capacitor is characterized in that the electrolytic solution of the low pressure aluminum electrolytic capacitor is stirred at room temperature for 60 to 120 minutes. Of electrolyte solution The method of claim 3, wherein the weight ratio of the imidazole salt of maleic acid to the imidazole salt of phthalic acid is 60:40 to 40:60.