JPH033370B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrolytic solution for an electrolytic capacitor containing a tetrafluoroborate of a nitrogen hetero-condensed ring compound as an electrolyte in an aprotic solvent. [Prior Art] Traditionally, organic acids or their salts/glycol-based pastes have been mainly used as electrolyte solutions for electrolytic capacitors for normal applications, but due to the recent increase in the range of use of electronic devices, capacitor performance has improved. With the increasing demand for improvements in paste properties, the presence of water in pastes has become a major problem, and electrolytic solutions that use aprotic solvents to replace organic acids or their salts/glycol pastes are attracting attention. However, the biggest problem with aprotic solvent-based electrolytes is how to obtain electrolytes with high conductivity. The search for organic carboxylic acids or their salts has been the main focus, but this goal has not yet been achieved, and it is unavoidable that solvents that react with acids such as alcohols and glycols to produce water, and furthermore, that Attempts have been made to obtain high conductivity by blending it into a proton solvent, but the current situation is that it cannot achieve a sufficiently high conductivity, and that it lacks stability at high temperatures due to increased water content and electrolyte. Therefore, it is an object of the present invention to provide a substantially non-aqueous highly conductive electrolyte using an aprotic solvent. [Problems to be Solved by the Invention] The present inventors have solved the problem by using an aprotic solvent and without using a solvent that reacts with acids such as alcohols and glycols to produce water. As a result of extensive research into an aqueous electrolyte that provides high conductivity, we found that a nitrogen hetero-condensed ring compound salt of tetrafluoroboric acid (HBF ₄ ) has high solubility in aprotic solvents and has a low degree of dissociation. The present invention was achieved by discovering that high conductivity can be imparted. That is, the electrolytic solution for electrolytic capacitors according to the present invention has the general formula (In the formula, m=0 or 1, m+n=2 or 3, R ₁ =
The presence or absence of an alkyl substituent having 1 to 3 carbon atoms, R=H or one or two alkyl groups having 1 to 5 carbon atoms, the nitrogen atom is a nitrogen hetero 2 constituting a tertiary or quaternary amine. It is characterized by containing a tetrafluoroborate salt of a fused ring compound (compound containing 0 to 5 mutually conjugated double bonds in the ring) as an electrolyte. The nitrogen hetero two condensed ring compounds that are the object of the present invention include quinoline, 2-methylquinoline (quinaldine), isoquinoline, their partially or completely hydrides, and N for the above compounds.
-Alkylated compounds; Examples include indole, 3-methylindole (skatole), isoindole, pseudoindole, partially or completely hydrogenated products thereof, and N-alkylated compounds of the above compounds. The aprotic solvents used include (1) amide solvents N-methylformamide, N-dimethylformamide, N-ethylformamide, N-diethylformamide, N-methylacetamide,
N-dimethylacetamide, N-ethylacetamide, N-diethylacetamide, hexamethylphosphorinamide. (2) Sulfoxide-based dimethyl sulfoxide (3) Nitrile-based acetonitrile (4) Cyclic ester, amide-based γ-butyrolactone, N-methyl-2-pyrrolidone ethylene carbonate, propylene carbonate, etc. are representative examples, but are not limited to these. It's not a thing. The electrolytic solution for electrolytic capacitors according to the present invention is generally prepared by adding an equivalent amount of a desired nitrogen hetero-condensed ring compound to an aqueous solution of tetrafluoroboric acid, and then reducing the pressure to obtain an anhydrous salt. It can be easily prepared as an approximately 10% by weight solution in a protic solvent. [Example] Below, as an example of the electrolyte solution for electrolytic capacitors according to the present invention, the conductivities of 10% by weight solutions of various nitrogen hetero-condensed ring compounds tetrafluoroborates in various aprotic solvents are shown in Table 1. show. As a comparative example, a conventional standard electrolyte (78% ethylene glycol, 12% water, 10% ammonium adipate) was used as a comparative example.
%) are shown.

【table】

【table】

[Table] Next, Table 2 shows the life characteristics of the electrolytic solutions of Examples 1 to 12 and Reference Examples at 50 V and 22 μF.

〔Effect of the invention〕

According to the electrolytic solution according to the present invention, it is possible to provide a non-aqueous electrolytic solution having a high conductivity comparable to or higher than that of conventional glycols, water, and organic acid salts, and is suitable for use in the design field of electrolytic capacitors. provides a new and wide range of performance options.

Claims (1)

[Claims] 1. General formula in an aprotic solvent In the formula, m=0 or 1, m+n=2 or 3, R ₁ =
The presence or absence of an alkyl substituent having 1 to 3 carbon atoms, R=H, or one or two alkyl groups having 1 to 5 carbon atoms, the nitrogen atom is a nitrogen hetero 2 constituting a tertiary or quaternary amine. An electrolytic solution for an electrolytic capacitor containing, as an electrolyte, a tetrafluoroborate salt of a fused ring compound containing 0 to 5 mutually conjugated double bonds in the ring. 2 The aprotic solvent is N-methylformamide,
N-dimethylformamide, N-ethylformamide, N-diethylformamide, N-methylacetamide, N-dimethylacetamide, N-ethylacetamide, N-diethylacetamide,
The electrolytic solution for an electrolytic capacitor according to claim 1, which is selected from the group of γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, acetonitrile, or a mixture thereof.