JPS631021A - Electrolyte for 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 Field of Application According to the present invention, an excellent electrolytic solution for capacitors (hereinafter sometimes simply referred to as electrolytic solution) with high conductivity can be obtained.

[Prior art] The characteristics of a capacitor are determined by various factors, but in particular, the characteristics of the electrolyte that is housed in the outer case together with the capacitor element have a large effect on the impedance or equivalent series resistance (ESR). It is clear that

For example, electrolytic capacitors for medium and high voltage use an electrolytic solution in which boric acid or its ammonium salt is dissolved in an ethylene glycol solvent, but this has the drawbacks of low conductivity and high equivalent series resistance of the capacitor. ing.

Therefore, it cannot be used for applications that require low equivalent series resistance even in the high frequency range, such as smoothing of switching regulators that have been frequently used in recent years.

In addition, because the ethylene glycol solvent used in this electrolyte has a high viscosity and a relatively high freezing point, the conductivity of the electrolyte decreases significantly at low temperatures, and the low-temperature characteristics of the electrolytic capacitor deteriorate. Due to the large amount of water produced by the esterification reaction between glycol and boric acid, it cannot be used in electrolytic capacitors with temperatures exceeding 100°C, and has the disadvantage of a narrow operating temperature range.

The inventors of the present invention conducted extensive studies to resolve the drawbacks of the boric acid-based electrolyte, and found that r-butyrolactone, which the conventional ammonium salts of boric acid were unable to solve, was found to be difficult to solve. N.

The present invention was completed by discovering that a quaternary ammonium salt of boric acid dissolves in an aprotic solvent such as N-dimethylformamide and exhibits high conductivity.

That is, the present invention provides an electrolytic solution for a capacitor characterized by using a quaternary ammonium salt of boric acid as a solute.

Detailed Description of the Invention Examples of the quaternary ammonium salt of boric acid used as a solute in the present invention include tetraethylene ammonium, tetrapropylammonium,
Aliphatic quaternary ammonium salts such as tetrabutylammonium, methyltriethylammonium, methyltripropylammonium, methyltributylammonium, dimethyldiethylammonium, dimethyldipropylammonium, dimethyldibutylammonium, ethyltripropylammonium, nityltriptylammonium,
N,N-dimethylpyrrolidinium, N,N-dimethylpiperidinium, N-methyl-N-ethylpyrrolidinium, N-methyl-N-ethylpiperidinium, N,N-pentamethylenepiperidinium, etc. Examples include alicyclic quaternary ammonium salts and aromatic quaternary ammonium salts such as N-ethylpyridinium.

Examples of the solvent for dissolving the quaternary ammonium salt of boric acid of the present invention include N-methylformamide, N-ethylformamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylacetamide, N-ethylacetamide, N,N-dimethylacetamide, N,N
- Amide solvents such as diethylacetamide and N-methylpyrrolidinone, lactone solvents such as r-butyrolactone, r-valerolactone and δ-valerolactone, carbonaceous solvents such as ethylene carbonate, propylene carbonate and butylene carbonate, ethylene glycol, Examples of fG media include alcohol solvents such as glycerin and methyl cellosolve, nitrile solvents such as 3-methoxypropimannitrile, and phosphoric acid ester solvents such as trimethyl phosphate, either singly or in combination.

The amount of the quaternary ammonium salt of boric acid dissolved in the above solvent is below the saturation concentration, preferably 9 to 40% by weight.

Further, the dissolved salt in the electrolytic solution may be a neutral salt or an acidic salt.

The electrolytic solution of the present invention essentially consists of a quaternary ammonium salt of boric acid and a solvent, but has the following properties: prevention of galvanic corrosion, reduction of leakage current, etc.
Small amounts of co-solutes may be added for various purposes.

Effect of the invention.

The quaternary ammonium salt of boric acid used as a solute in the present invention has good solubility in solvents, and its electrolyte exhibits high conductivity. By using it together with a solvent with a wide range of freezing point to boiling point, it can be used in a wide temperature range. Becomes electrolyte for capacitors.

EXPERIMENTAL EXAMPLES The non-invention will be explained in more detail with reference to Examples and Comparative Examples below.

-Example: An electrolytic solution was obtained by dissolving 1ON of tetraethylammonium salt of boric acid in an r-butyrolactone solvent. The conductivity of this electrolytic solution at 25° C. was 4.9 mS/cm, and the spark generation voltage when a constant current of 4 mA/i was applied to a pair of ammonium f# foils was 330 μm. Further, the temperature change in the conductivity of this electrolytic solution is shown in FIG. 1 (e+).

Examples 2-4 In Example 1, the r-butyrolactone solvent was N.

Table 1 shows the conductivity of the electrolyte when N-dimethylformamide (Example 2), propylene carbonate (Example 3), and propylene carbonate (Example 4) were used instead.

Comparative Examples 1 to 4 Table 1 shows the results when the solvents used in Examples 1 to 4 were used, but the solute was changed to conventional ammonium borate. In addition, the temperature change in the conductivity of the electrolytic solution of Comparative Example 4 is shown in Figure 1 (illustration).
It was shown to.

In Table 1, the following abbreviations were used.

GBL: r-butyrolactone DMF: N,N-dimethylformamide PC:
Globylene Carbohydrate EG: Ethylene Glycol Table 1

[Brief explanation of the drawing]

Figure 1 is a diagram showing temperature changes in the electrical conductivity of the electrolytic solutions obtained in Example 1 (o) and Comparative Example 4 (-). October 2a, 2003; Secretary of the Japan Patent Office Kuro 1) Akio Nie 11
−. 1. Indication of the incident 1985 Patent Application No. 144588 2
, Title of the invention: Electrolytic solution for capacitors 3, Relationship with the case of the person making the amendment Patent applicant address: 2-5-2 Marunouchi, Chiyohi-ku, Tokyo Name (6
05) Mitsubishi Yuka Co., Ltd. 4, Agent Address: 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Yuka Co., Ltd. Column 6 of "Detailed Description of the Invention" in the Specification, Contents of Amendment (A) No. Page 3, line 9, “tetraethylene ammonium” was corrected to “tetraethylammonium” (b) Same page, line 15, “ethyl” IJ f ropylammonium, nichi”
(Ethyltrif'o pylammonium, ethyl.) → Corrected page 4, line 14, ``Carbonate and solvent'' to ``Cargarnate solvent'') Page 5, line 1, ``9 to 40 weight'' Corrected as “1-40 weight” (E) No. 6
On the 3rd line of the page, "on a smooth foil" is corrected to "on a smooth foil" (to) On the 9th and 10th lines of the same page, "glopylene cardinate (Example 4)" is corrected as "ethylene glycol (Example 4)" (g) Page 7, table 1, line 1, “conductor” is corrected to “conductivity”

Claims (1)

[Claims] An electrolytic solution for capacitors characterized by using a quaternary ammonium salt of boric acid as a solute.