JPS637613A - Electrolyte for 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] [Industrial Application Field] The present invention relates to an electrolytic solution for electrolytic capacitors,
By significantly lowering the specific resistance of the electrolyte,
Long, L? This is a life-saving and highly reliable electrolytic capacitor.

[Prior art and bending point] Conventionally, permeate acid-based electrolytes containing relatively large molecular weight organic acids or their salts as solutes have been used and studied for high-temperature electrolytic capacitors.

As a solute of an organic acid-based electrolyte for medium and high pressures, 1.6-decane dicarboxylic acid (Japanese Patent Publication No. 13293/1983) is known, or this 1.6-
In electrolytic capacitors that use an electrolyte containing decanedicarboxylic acid, the solute itself reacts with the aluminum foil that forms the capacitor element and forms a complex, resulting in a low initial capacitance. An extreme decrease in capacitance and a significant increase in leakage current were observed, and the demand for higher performance electrolytic capacitors could not be met. For this reason, it is used as an additive.
, 6-decanedicarboxylic acid and maleic acid (JP-A-58-
No. 92208r electrolytic solution for driving electrolytic capacitors") or citric acid (JP-A No. 59-219920? Electrolytic solution for driving electrolytic capacitors") have been proposed, but they still have poor thermal stability. It corrects the following shortcomings.

[Improvements and Summary of the Invention] However, the present invention can eliminate the above-mentioned drawbacks, and specifically, by adding L-amino acids as an additive to 1,6-decanedicarboxylic acid. .6-Preventing complex formation between decanedicarboxylic acid and aluminum foil to suppress electrostatic capacitor changes and increases in leakage current, and further lowering the specific resistance of the electrolyte to reduce loss angle tangent and high frequencies. By reducing the impedance of the capacitor, we provide an electrolytic capacitor with higher performance and reliability. In the present invention, examples of L-amino acids include glycine, aspartic acid, alanine and glutamic acid.

[Example] Next, an example of an electrolytic solution according to the present invention, which mainly consists of the above-mentioned 1,6-decanedicarboxylic acid or its salt, is dissolved in a batter polar solvent, and L-amino acids are added. This is shown in Table 1 along with conventional examples. lE solution composition wt%, specific resistance (
Ωcm) is at the liquid temperature of 20°C. Further, the spark voltage was at 85°C.

Table 1 Examples of Electrolyte Composition Next, among the electrolytes shown in Table 1, Conventional Example 1, Conventional Example 2. Table 2 shows the results of a high-temperature load test at a temperature of 105° C. and application of the rated voltage for 1000 hours on 20 electrolytic capacitors (rated at 400 μF and 10 μF) using the electrolytes of Examples 3 and 4. . Further, Table 3 shows the results of a high temperature load test (105° C., 1000 hours) on an electrolytic capacitor (rated 400 V, 220 μF).

(8 values of initial and post-test characteristics are for electrolytic capacitors 42
This is the average value of 0. ) L Effect of the Invention] As can be seen from Tables 2 and 3, in Conventional Examples 1 and 2, the initial capacitance value was low after about 5%ti of the rated value, and the rate of change was even after the test. big. Further, as can be seen from Table 3, the leakage current in Conventional Example 1 and Conventional Example 2 is approximately 30 times greater.

This phenomenon in the conventional example shown in Tables 2 and 3 is caused by the reaction of 1,6-decanedicarboxylic acid in the driving electrolyte with the aluminum foil forming the capacitor element, as described above. The capacitance decreases without being sufficiently effective in preventing a significant decrease in surface area, and the increase in leakage current is due to the fact that 1,6-decanedicarboxylic acid is the dielectric material of the aluminum anodic oxide film. The reaction results in the formation of an unstable aluminum shell, and the stiffness dissolves into the driving electrolyte at high temperatures, increasing leakage current.

On the other hand, the present invention suppresses complex formation of 1,6-decanedicarboxylic acid by adding L-amino acids to a solute mainly composed of 1,6-decanedicarboxylic acid or a salt thereof. Furthermore, by lowering the specific resistance, the tangent of the loss angle and the impedance at high frequencies can be kept low.

Claims (1)

[Scope of Claims] [1] An electrolytic solution for driving an electrolytic capacitor containing 1,6-decanedicarboxylic acid or a salt thereof, characterized in that an L-amino acid is added thereto. [2] The electrolytic solution for driving an electrolytic capacitor according to claim [1], wherein the L-amino acids are any one of glycine, L-aspartic acid, alanine, and glutamic acid.