JPH01171222A - Driving electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain excellent characteristics in a wide temperature range, by dissolving choline carboxylate by using gamma-butyrolactone as a main solvent. CONSTITUTION:Choline carboxylate is dissolved by using gamma-butyrolactone as a main solvent, and this is made driving electrolyte for an electrolytic capacitor. Carboxylic acid is desirable to be composed of phthalic acid or maleic acid or resorcylic acid. The addition quantity of solute is desirable to be more than or equal to 5g for solvent of 100g. In the case where the quantity is less than or equal to 5g, the resistivity can not be sufficiently reduced. It is not desirable that the addition quantity exceeds the saturation concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as electrolytic solution).

2. Description of the Related Art Conventionally, as an electrolytic solution for electrolytic capacitors, an electrolytic solution in which an adipate salt is dissolved in a solvent mainly composed of ethylene glycol has been frequently used.

Problems to be Solved by the Invention In recent years, as aluminum electrolytic capacitors have become lower in impedance, smaller in size, and more reliable, there has been a demand for electrolytic solutions that have low specific resistance and are stable over a wide range of temperatures. Conventionally, in order to lower the specific resistance of an electrolytic solution in which adipate is dissolved in a solvent mainly composed of ethylene glycol,
There are some solutions in which the blending ratio of water in the electrolytic solution is increased or the amount of solute is increased, but when the blending ratio of water is increased, the reliability in a high temperature atmosphere decreases significantly. Increasing the amount of solute caused problems such as deterioration of low-temperature characteristics such as capacitance and loss. Further, even though various studies were conducted to consider the increase in viscosity of ethylene glycol at low temperatures, the lower limit of the usable temperature range was -40°C.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an electrolytic solution for an electrolytic capacitor characterized by using γ-butyrolactone as a main solvent and dissolving a choline salt of carboxylic acid.

Function: The electrolytic solution according to the present invention has extremely high solubility of solute and extremely low specific resistance. Furthermore, since there is no precipitation of solutes even at low temperatures and the change in viscosity of the solvent is extremely small, the low-temperature characteristics of the capacitance and loss of aluminum electrolytic capacitors are also significantly improved.

Example Examples of the present invention will be described below.

Table 1 shows the electrolyte composition and the specific resistance values of the electrolyte at temperatures of 30°C and -55°C.

As is clear from Table 1, the electrolytic solution according to the present invention has a lower specific resistance value than the conventional electrolytic solution, and provides an extremely low specific resistance value even at low temperatures.

Table 2 shows the rated 1 prototype manufactured using the electrolyte shown in Table 1.
The temperature characteristics of a 0WV 100μF aluminum electrolytic capacitor are shown.

ffi 2 harm From Table 2, electrolyte sample symbols A, B, C, D, and E.

The products of the present invention using F, G, H1■, and J have significantly improved characteristics at low temperatures compared to conventional products using electrolyte sample code K.

Table 3 shows the results of a high-temperature load test in which a capacitor with the same rating as above was fabricated using the electrolytic solution shown in Table 1 and a rated voltage was continuously applied at 105°C. Leakage current indicates the value 1 minute after the rated voltage is applied. Each characteristic value is an average value of 20 samples.

Table 3 Electrolyte sample symbols A, B, C, D as shown in Table 3
, E, F, G, H, I, and J of the present invention exhibits small capacitance change rate and loss change even in high-temperature load tests, and provides excellent durability. The choline salts of carboxylic acids are not limited to the combinations of the above-mentioned examples, and two or more types may be combined.

Further, the amount of solute added is preferably 5 g or more per solvent long, and if it is less than 5 g, the specific resistance cannot be sufficiently lowered. Note that it is not preferable that the amount added exceeds the saturation concentration.

Effects of the Invention As is clear from the above results, the electrolytic solution for driving aluminum electrolytic capacitors, which is characterized by using γ-butyrolactone as the main solvent and dissolving a choline salt of carboxylic acid, has excellent characteristics over a wide temperature range. It is of great industrial and practical value.

Claims (3)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor characterized by using γ-butyrolactone as a main solvent and dissolving a choline salt of carboxylic acid. (2) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the carboxylic acid consists of phthalic acid, maleic acid, or resorcylic acid. (3) The electrolytic solution for driving an electrolytic capacitor according to claim 1 or 2, wherein the choline salt of carboxylic acid is present in an amount of 5 g or more per 100 g of the mixed solvent.