KR20040011771A - Electrolyte and chip-type Al eletrolytic condenser using it - Google Patents

Abstract

PURPOSE: An electrolyte and a chip type aluminum electrolytic capacitor using the same are provided to boost a spark voltage by using a compound of a derivative of silicon dioxide and an arbitrary solvent and imidazole-based quaternary salt. CONSTITUTION: An electrolyte is formed by melting imidazole-based quaternary salt in a compound of a derivative of silicon dioxide and an arbitrary solvent. The derivative of silicon dioxide is composed of a predetermined chemical expression. The content of the derivative of silicon dioxide is 0.5 to 20 weight percents. The solvent is formed with one or more solution or mixed solution of r-butyrolactone, ethylene glycol, sulpholane, and water. The density of the imidazole-based quaternary salt is 20 to 30 weight percents. The imidazole-based quaternary salt is cleaned by using one or more solvent of acetone and toluene.

Description

Electrolyte and Chip-type Aluminum Electrolytic Capacitor (Ⅰ) {Electrolyte and chip-type Al eletrolytic condenser using it}

The present invention relates to an electrolyte solution in which the spark voltage is increased by using a specific additive and an aluminum electrolytic capacitor using the same. More specifically, a silicon dioxide system having a high withstand voltage, high stability and high purity in any solvent An electrolytic solution for dissolving and preparing imidazole quaternary salts in a compound obtained by synthesizing and adding a derivative (SiO 2 -X) to increase the spark voltage, as well as to increase the use voltage and to lower the specific resistance, and a chip type aluminum electrolytic capacitor using the same. will be.

Conventionally, as electrolyte solution used for a chip-type aluminum electrolytic capacitor element, invention which made the solute the quaternary ammonium salt of aromatic carboxylic acid (phthalic acid etc.) (U.S. Patent No. 4715976), and the invention which used the amidine quaternary salt as a solute. (Japanese Patent 10-0237116), etc. are known.

Recently, with the miniaturization, high functionality, and chip size of electronic devices, switching power regulators adopted in various electronic devices such as communication devices, computer input / output units, inverters, and automotive electronic parts have low loss, low impedance, ripple resistance, high heat resistance, long life, and the like. There is a need for an electrolyte having the characteristics of. However, until now, when an aluminum electrolytic capacitor was manufactured using an electrolyte solution of aromatic carboxylic acid (phthalic acid, etc.) of US Pat. No. 4715976, rubber with excess hydroxide ions generated by electrolysis of a quaternary ammonium salt on the negative potential electrode side was used. The sealing body deteriorates, the sealing performance is considerably lowered, and there is a problem that eventually causes liquid leakage. In addition, the electrolyte solution containing amidine quaternary salt of Japanese Patent No. 10-0237116 has not only high vapor pressure but also high flame voltage of the electrolyte solution. Due to the limited use voltage of the capacitor (below 35WV), it was difficult to apply to automobile equipment. Also, the removal of unreacted material, which is a starting material, was performed by distillation at high temperature. Since the break point of the reactants (approximately 200 ° C.) is quite high, thermal stress on the quaternized cations Residuals of unreacted materials in the electrolyte are increased due to the increase of pH on the cathode side during electrolysis of the electrolyte. This is unsuitable for deteriorating the raw materials and ultimately applying them to long life low impedance products.

The present invention provides an electrolyte solution for solving such problems, namely, an electrolyte solution having an effect of improving thermal stability, high non-conductivity, increasing spark voltage, and protecting a defective portion of the foil by forming a complex with the electrode foil. And an aluminum electrolytic capacitor using this electrolyte solution.

1 is a schematic diagram of an aluminum electrolytic capacitor.

<Description of the symbols for the main parts of the drawings>

One; Anode foil 2; Cathode foil

3; Quarantine 4; Withdrawal lead

The electrolyte solution according to the present invention is composed of a silicon dioxide derivative, an optional solvent, and an electrolyte for the purpose of raising the spark voltage, and, if necessary, an additive such as another gas absorbent is added to constitute the electrolyte solution. Each component of the electrolyte is excellent in stability at high temperatures, in particular, silicon dioxide derivatives further improve the stability at high temperatures, increase the spark voltage, and also remove the unreacted substances in the electrolyte manufacturing process It is possible to provide a better chip-type aluminum electrolytic capacitor by applying a washing method for. To describe the components of the electrolyte in more detail,

First, the electrolyte solution depends on the characteristics of the capacitor according to the additive. In the present invention, the thermal conductivity and high purity silicon dioxide-based derivatives, etc., as an additive represented by the following chemical formula, do not lower the conductivity of the electrolyte without a drop in the flame voltage (withstand voltage) Not only increases the operating voltage of the capacitor, but also forms a strong complex with the aluminum electrode foil to protect the defective portion, and has a function of suppressing the occurrence of a short circuit due to an avalanche. Long life and low impedance can be realized. The silicon dioxide derivative according to the present invention was synthesized by reacting at 130 ° C. for 3 hours in an ethylene glycol solvent, and the concentration was 20% by weight of the solution. The content of the silicon dioxide derivative in the electrolyte is preferably 0.5 to 20% by weight. If the silicon dioxide derivative content is 0.5% by weight or less, there is no effect to increase the flame voltage, 20% by weight or more is not good because there is a possibility of precipitation.

Secondly, the solvent used in the present invention is composed of lactone, sulfolane, polyalcohol, water and the like, and a single or mixed solvent is applied.

Third, the electrolyte uses an imidazole quaternary salt. The imidazole quaternary salt has a great influence on the electrical characteristics of the capacitor depending on the degree of synthesis, that is, the residual amount of unreacted matter and other impurities. In the present invention, in the manufacturing process of the imidazole quaternary salt, the removal of the unreacted material can obtain a high purity quaternary salt by washing with a solvent (toluene, benzene, acetone, etc.) rather than the conventional distillation method. The method by washing is capable of purifying quaternary salts as well as removal of unreacted materials, thereby inhibiting deterioration of the sealing material and improving service life by pH stabilization at the cathode side during electrolysis.

Fourth, the electrolyte of the present invention includes a phosphoric acid derivative, a nitro compound if necessary.

The components of the above-mentioned electrolyte solution of the present invention have a great influence on the characteristics of the aluminum electrolytic capacitor depending on how they are combined and selected. The solvent for the electrolyte of the present invention is preferably a r-butyrolactone or a sulfolane solvent and may be single or mixed. When water is used in combination with an organic solvent, 0.5 wt% or less of the electrolyte may be used. desirable. If the value is equal to or larger than the above value, the negative electrode foil constituting the capacitor deteriorates in hydration and vapor pressure, resulting in shortening the life of the capacitor. In addition, the content of the electrolyte (solute) relative to the electrolyte is generally preferably 20 to 30% by weight. More than 30% by weight is not very effective in increasing the conductivity, and less than 20% by weight is not thermally stable, and the conductivity is low and the electrical characteristics of the capacitor are not good. The pH of the electrolyte solution of the present invention is preferably from 6 to 8, more than that promotes deterioration of the sealing material by alkalinization, resulting in a shortened life.

EXAMPLE

(Silicon dioxide derivative derivative production example 1)

1 liter of ethylene glycol and 200 g of silicon dioxide (SiO ₂ ) were added to a round flask, and heated and stirred at 130 ° C. for 3 hours, dissolved, and cooled to measure physical properties. Flame voltage 700V (30 degreeC), moisture is 1.1%. Smooth foil was used for flame voltage measurement, and current density was measured under the condition of 10 mA / cm 2.

(Example 2 of silicon dioxide derivative)

A solvent other than ethylene glycol (Sulfolane, r-butyrolactone, etc.), which is a solvent in Preparation Example 1, may also be prepared, but it is not applied to the examples in the present invention.

(Examples 1 to 6 and Conventional Examples 1 to 4)

Table 1 below shows the comparative results of the electrolyte solution properties after the high-temperature heat treatment of Examples 1, 2, 3, 4, 5, 6 and Conventional Examples 1, 2, 3, and 4. The test conditions were to compare the changes in physical properties measured after leaving 200g of electrolyte at 130 ° C for 1000 hours.The comparison items were non-conductivity (ms / cm, 30 ° C), pH (25 ° C), and flame voltage (V / 30 ° C.).

The foil was used for the measurement of the spark voltage (spark voltage), the current density was measured under the condition of 10mA / ㎠.

Table 1

In Table 1, GBL is r-butyrolactone.

As can be seen in Table 1, Examples 1 and 2 of the present invention and the conventional examples 1, 3, 4 and the conventional example 2, Example 6 and the conventional example 3, Example 5 and the conventional example 4 can be compared In the case, the initial conductivity and the non-conductivity after heat treatment were high, and the result of the small rise in pH was obtained. In addition, when comparing the embodiment of the present invention with the conventional example, the embodiment of the present invention obtained a higher spark voltage. Therefore, it can be seen that the action of the silicon dioxide derivatives not only contributes to thermal stabilization, but also increases the spark voltage.

(Example 7 and Conventional Example 5)

Table 2 below shows the results of electrolysis of the electrolyte solutions of Example 7 and Conventional Example 5. The electrolysis test apparatus is an H-type flask electrolyzer, in which a glass filter separator having a pore size of 5 μm is provided between the positive electrode and the negative electrode. As a positive electrode, an aluminum aluminum foil of 65 µm having a purity of 99.999% was used, and a carbon electrode was used as a negative electrode. When the constant current (20 mA) was applied, the pH was measured to compare the degree of basicization with time on the negative side.

Table 2

Example 7 of Table 2 is the same as the electrolyte solution of Example 3, and the prior art example 5 is the same electrolyte solution as the prior art example 2. As a result of the above Table 2, it can be seen that the conventional example is more alkaline. There are two main reasons for this, one of which is that the silicon dioxide derivative of Example 7 serves to suppress alkalizing, and the other is because of the relatively high degree of unreacted residue in the imidazole preparation process. This may occur due to the difference in the method of removing unreacted materials. Example 7 removes unreacted materials and impurities with a solvent such as acetone several times, while in the conventional example 4, unreacted materials (bp: about 200 ° C.) are removed by distillation. Since it can be subjected to thermal stress, it is difficult to remove impurities and the like. As a result, alkalizing results in deterioration of the encapsulant.

(Examples 8-11 and Conventional Examples 6-8)

Table 3 below shows the results of a comparison test with or without a short circuit when the overvoltage is applied to Examples 8 to 11 and Conventional Examples 6 to 8.

The test was performed using aluminum electrolytic capacitor of rated voltage 50WV, capacitance 1000 ,, size (φ16XL31.5), and the test condition was observed by applying an overvoltage of 70V.

Table 3

Examples 8, 9, 10, and 11 are the same electrolyte solutions as in Examples 2, 3, 4, and 5, respectively, and Conventional Examples 6, 7, and 8 are the same electrolyte solutions as the prior art examples 2, 3, and 4, respectively. As a result of Table 3, among the components of the electrolyte solution in the present invention, by applying an additive of silicon dioxide derivative, the spark voltage of the electrolyte is increased, and as a result, the withstand voltage of the aluminum electrolytic capacitor is improved.

Next, a configuration of the chip-shaped aluminum capacitor using the electrolyte according to the present invention obtained as described above will be described with reference to FIG. 1. As shown in FIG. 1, an insulating paper is formed between an anode foil 1 as an anode electrode having a predetermined myth coating coated on an etching pit having an enlarged surface area of aluminum, and a cathode foil 2 as a cathode electrode made of the same aluminum. (3) The device is constructed by winding up so as to face through (insulated paper). The lead lead 4 extends vertically in the positive electrode foil and the negative electrode foil. The chip-shaped aluminum electrolytic capacitor according to the present invention is constituted by impregnating the electrolytic solution of the present invention in the device thus constructed and encapsulating it in an aluminum case, followed by curling and encapsulation together with the sealing material.

The electrolyte according to the present invention obtained as described above has a high non-conductivity, high thermal stability, forms a strong complex with the aluminum electrode foil to protect the defects, suppresses the occurrence of a short circuit due to an avalanche and increases the flame voltage. In addition, in the synthetic manufacturing process of the imidazole quaternary salt, the removal of unreacted material by washing with a solvent (acecone, toluene, benzene, etc.) to obtain a high-purity quaternary salt to obtain a high-purity quaternary salt, and also the present invention When used in an aluminum electrolytic capacitor, a long-life, low-impedance capacitor with low loss and stable electrical characteristics at high temperatures can be realized, as well as an increase in operating voltage due to an increase in the voltage of the electrolyte.

Claims (6)

An electrolyte solution comprising dissolving an imidazole quaternary salt in a compound obtained by synthesizing a silicon dioxide derivative of the following formula in an arbitrary solvent. The electrolyte of claim 1, wherein the content of the silicon dioxide derivative is 0.5 to 20 wt%. The electrolyte of claim 1, wherein the solvent comprises at least one single or mixed solution of r-butyrolactone, ethylene glycol, sulfolane, and water. The electrolyte of claim 1, wherein the concentration of the imidazole quaternary salt is 20 to 30% by weight. The electrolyte according to claim 1 or 4, wherein the unreacted material is removed in the synthesis process of the imidazole quaternary salt by washing with at least one solvent selected from acetone and toluene. A chip-type aluminum electrolytic capacitor manufactured using the electrolyte solution of claim 1 to claim 5.