JP6174920B2 - Non-aqueous electrolyte for electric double layer capacitors - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte for an electric double layer capacitor and an electric double layer capacitor.

  An electric double layer capacitor (EDLC) is characterized by storing electricity by utilizing the phenomenon that ions in an electrolyte form an electric double layer by physical adsorption with an electrode when an electric field is applied to the electrolyte. Power storage device. The electric double layer capacitor is widely used in, for example, an instantaneous power failure compensation device (UPS) because it has a higher charge / discharge speed than a secondary battery such as a lithium ion battery that generates electricity by a chemical reaction. In recent years, society's demands on the environment and energy efficiency have become more and more stringent. Recently, taking advantage of its characteristics, energy regeneration from automobiles, auxiliary power, standby power storage equipment for wind power, etc., standby for copying machines, etc. As a power source for power supply and the like at the time of return from the state, demand is increasing widely and is one of the power storage devices that attract attention.

  In recent years, demands for improving the output density and energy density of electrochemical devices such as batteries and capacitors have increased, and from the viewpoint of voltage resistance, organic electrolytes (non-aqueous electrolytes) are more frequently used than aqueous electrolytes. It is being done.

  Examples of the organic electrolyte include an electrolyte obtained by dissolving a solid ammonium salt (electrolyte), for example, a linear aliphatic ammonium salt such as tetraethylammonium salt or triethylmethylammonium salt in an organic solvent such as propylene carbonate (Patent Document 1). ), N-ethyl-N-methylpyrrolidinium salt (Patent Document 2), and a cyclic aliphatic ammonium salt such as spiro- (1,1) -bipiperidinium salt dissolved in an organic solvent such as propylene carbonate ( Patent Document 3) is widely known and used. However, these electrolytes have a problem that they are not sufficiently durable when used in electric double layer capacitors.

Japanese Patent Publication No. 03-58526 Japanese Patent Publication No. 08-31401 JP 2008-210871 A

  This invention makes it a subject to provide the non-aqueous electrolyte which gives the electrical double layer capacitor excellent in durability in view of the said present condition.

  As a result of intensive studies to develop an electrolyte for a capacitor and an electrolytic solution that can solve the above-mentioned problems, the inventors have determined that the alkali metal cation concentration is 0.1 to 30 ppm in a nonaqueous electrolytic solution containing a quaternary ammonium salt. Then, it discovered that the electrical double layer capacitor manufactured using this electrolyte solution had the outstanding durability, and completed this invention based on this knowledge.

That is, the present invention includes the following contents.
(1) The following general formula (I) as an electrolyte in a non-aqueous solvent:
Q ⁺ X ⁻ (I)
(In the above formula, Q ⁺ represents a quaternary ammonium cation, and X ⁻ represents PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , SbF ₆ ⁻ and RfSO ₃ ^−. (Wherein Rf represents a counter ion selected from the group consisting of a C1-C8 fluoroalkyl group) dissolved in a quaternary ammonium salt (excluding spiro-type quaternary ammonium tetrafluoroborate) A nonaqueous electrolytic solution for an electric double layer capacitor, wherein the nonaqueous electrolytic solution contains 0.1 to 30 ppm of an alkali metal cation.
(2) The non-aqueous electrolyte according to (1) above, wherein the alkali metal cation content is more than 10 ppm and 30 ppm or less.
(3) The non-aqueous electrolyte according to (1) or (2) above, wherein the alkali metal cation content is 12 to 30 ppm.
(4) The nonaqueous electrolytic solution according to any one of (1) to (3), wherein the alkali metal cation is sodium ion and / or potassium ion.
(5) The nonaqueous electrolytic solution according to any one of (1) to (4), wherein the quaternary ammonium cation is tetraalkylammonium or pyrrolidinium.
(6) The nonaqueous electrolytic solution according to any one of (1) to (5), wherein the quaternary ammonium cation is N-ethyl-N-methylpyrrolidinium.
(7) The nonaqueous electrolytic solution according to any one of (1) to (5), wherein the quaternary ammonium cation is N, N, N-triethyl-N-methylammonium.
(8) In formula (I) in wherein X ^-, BF ₄ ^- the, which is a (1) non-aqueous electrolyte according to any one of (1) to (7).
(9) The nonaqueous solvent is at least one selected from the group consisting of propylene carbonate, ethylene carbonate, butylene carbonate, sulfolane, methyl sulfolane, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate (1 )-(8) The nonaqueous electrolyte solution as described in any one of.
(10) An electric double layer capacitor comprising the nonaqueous electrolytic solution according to any one of (1) to (9) as an electrolytic solution.

  When the non-aqueous electrolyte of the present invention is used, an electric double layer capacitor excellent in durability in which a decrease in capacity (capacity deterioration) and an increase in resistance are reduced over a long period of time can be obtained.

Hereinafter, the present invention will be described in detail.
The nonaqueous electrolytic solution of the present invention is a nonaqueous electrolytic solution for an electric double layer capacitor in which a quaternary ammonium salt represented by the above general formula (I) is dissolved as an electrolyte in a nonaqueous solvent. The nonaqueous electrolytic solution of the present invention contains 0.1 to 30 ppm of an alkali metal cation.

When the alkali metal cation content in the nonaqueous electrolytic solution is 0.1 to 30 ppm, the electric double layer capacitor produced using the nonaqueous electrolytic solution is excellent in durability. When a plurality of types of alkali metal ions are included, the total of them is set within this range.
If an alkali metal cation exceeding 30 ppm is contained, there is a risk that the electric capacity of the electric double layer capacitor produced using the non-aqueous electrolyte is likely to be lowered (capacity deterioration is likely to occur). Moreover, when the alkali metal cation exceeding 30 ppm is contained, there is a possibility of causing a problem such as an increase in leakage current in the electric double layer capacitor produced using the non-aqueous electrolyte.

  The alkali metal cation content in the non-aqueous electrolyte is preferably more than 10 ppm and 30 ppm or less, more preferably 12 to 30 ppm. Within such a range, an electric double layer capacitor manufactured using a non-aqueous electrolyte has excellent durability with reduced capacity reduction (capacity deterioration) and resistance increase over a long period of time. Become.

  Examples of the alkali metal cation include lithium ion, sodium ion, potassium ion and the like. These may be one type or two or more types. Preferably, the alkali metal ion is sodium ion, potassium ion, or both. In a preferred embodiment of the nonaqueous electrolytic solution of the present invention, the total of sodium ions and potassium ions in the nonaqueous electrolytic solution is 0.1 to 30 ppm.

  A method for producing a non-aqueous electrolyte in which the content of the alkali metal cation is controlled in such a concentration range is not particularly limited. For example, the content of the alkali metal cation in the non-aqueous electrolyte may be adjusted by adjusting the content of the alkali metal cation in the non-aqueous solvent and / or electrolyte that is the raw material of the non-aqueous electrolyte. You may add an alkali metal separately to electrolyte solution. Especially, the method etc. which adjust alkali metal cation content in a nonaqueous electrolyte by adjusting the alkali metal cation content in the quaternary ammonium salt used as electrolyte solution are preferable. For example, the alkali metal cation content in the quaternary ammonium salt used in the production of the non-aqueous electrolyte is preferably about 0.2 ppm to 300 ppm, more preferably about 0.5 to 120 ppm. As a method for adjusting the alkali metal cation content in the quaternary ammonium salt, for example, in the production of the quaternary ammonium salt represented by the general formula (I) as an electrolyte, the alkali metal salt is changed during salt exchange. And a method of controlling the number of equivalents of reagents; including an electrolyte obtained by dissolving an electrolyte (a quaternary ammonium salt represented by the general formula (I)) with a solvent (poor solvent) having low solubility in alkali metal Examples include a method of removing an alkali metal that has not been dissolved in the poor solvent by filtering the solution. By such a method, a quaternary ammonium salt represented by the general formula (I) usually containing about 0.2 ppm to 300 ppm, preferably about 0.5 to 120 ppm of an alkali metal cation can be obtained. The obtained quaternary ammonium salt represented by the general formula (I) is added to a high purity (for example, purity of about 99.99% or more) non-aqueous solvent, for example, the concentration of the quaternary ammonium salt is about 0.1. A nonaqueous electrolyte solution having an alkali metal cation content of 0.1 to 30 ppm can be obtained by dissolution so as to be ˜3 mol / L.

  Among them, as a method for adjusting the alkali metal cation content in the quaternary ammonium salt represented by the general formula (I), an electrolyte is dissolved in a solvent (poor solvent) having low solubility with respect to an alkali metal, and the poor solvent The method of removing the alkali metal that did not dissolve in the solution by filtration is preferable because it is easy to operate and the numerical values can be easily managed. When adjusting the concentration of the alkali metal cation by this operation, the content of the alkali metal cation in the quaternary ammonium salt represented by the general formula (I) depends on the poor solvent used, the filtration temperature, and the like. For example, isopropyl alcohol, propylene carbonate, dichloromethane and the like are preferable as the poor solvent. For example, the filtration temperature is preferably about −10 to 50 ° C., more preferably about 0 to 25 ° C. The filtration method is not particularly limited, and may be performed by a normal method (under atmospheric pressure, under pressure, under reduced pressure). Moreover, the usage-amount of a poor solvent does not have a restriction | limiting in particular, What is necessary is just to add about 1 to 10 times by mass ratio with respect to the quaternary ammonium salt 1 represented by general formula (I). For example, in the case of using propylene carbonate as the poor solvent, the electrolyte (in the quaternary ammonium salt represented by the general formula (I)) was dissolved in propylene carbonate at about 5 to 50 ° C. and obtained. A method of filtering the solution at atmospheric pressure is preferred. When a non-aqueous electrolyte is produced using a quaternary ammonium salt represented by the general formula (I) obtained by such a method, the content of alkali metal cations in the non-aqueous electrolyte is usually 0.1. It can be controlled to ˜30 ppm.

  The amount of the alkali metal cation contained in the quaternary ammonium salt and the nonaqueous electrolytic solution can be measured by a known method such as ion chromatography. For example, when measuring by ion chromatography, for example, the conditions described in the Examples can be employed.

  The non-aqueous solvent in the present invention is not particularly limited, and examples thereof include propylene carbonate, ethylene carbonate, butylene carbonate, sulfolane, methyl sulfolane, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, gamma butyrolactone, and acetonitrile. 1 type of these may be used independently, or 2 or more types may be mixed and used. Among these, preferably, at least one of propylene carbonate, ethylene carbonate, butylene carbonate, sulfolane, methyl sulfolane, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate is preferable, and propylene carbonate is more preferable. As the non-aqueous solvent, a commercially available compound can be used, and it may be further purified by an arbitrary method and used.

  The concentration of the quaternary ammonium salt represented by the general formula (I), which is an electrolyte, in the nonaqueous electrolytic solution is preferably about 0.1 to 3 mol / L, particularly about 0.5 to 1.5 mol / L. preferable. Such a concentration range is preferable because the conductivity of the non-aqueous electrolyte is high. In addition, when the electrolyte concentration is in such a range, an increase in internal resistance of the electric double layer capacitor manufactured using the nonaqueous electrolytic solution can be more effectively suppressed. In addition, when the concentration of the electrolyte is within such a range, for example, even when the temperature becomes low, the salt hardly precipitates in the nonaqueous electrolytic solution, so that it is suitable for use at a low temperature.

In the present invention, a quaternary ammonium salt represented by the above general formula (I) is used as the electrolyte.
In the above general formula (I), Q ⁺ represents a quaternary ammonium cation. X ⁻ is a group consisting of PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , SbF ₆ ⁻ and RfSO ₃ ⁻ (Rf is a fluoroalkyl group having 1 to 8 carbon atoms). Represents the selected counter ion.
X ⁻ is preferably BF ₄ ^— .

As the quaternary ammonium cation (quaternary ammonium group) represented by Q ⁺ , any tertiary amine quaternized with an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or the like is used. . A hydroxyl group, an amino group, a nitro group, a cyano group, a carbonyl group, an ether group, an aldehyde group, or the like may be bonded to the hydrocarbon moiety forming the quaternary ammonium cation.

  Examples of the quaternary ammonium cation in the present invention include, for example, a tetraalkylammonium ion obtained by quaternizing nitrogen of a trialkylamine, a pyrrolidinium ion obtained by quaternizing nitrogen of a pyrrolidine ring, and a spiro quaternary quaternary. Ammonium ion, morpholinium ion formed by quaternization of nitrogen in morpholine ring, imidazolinium ion formed by quaternization of nitrogen in imidazoline ring, pyrimidinium formed by quaternization of nitrogen in tetrahydropyrimidine ring Ion, piperazinium ion formed by quaternization of nitrogen in piperazine ring, piperidinium ion formed by quaternization of nitrogen in piperidine ring, pyridinium ion formed by quaternization of nitrogen in pyridine ring, nitrogen in imidazole ring And quaternized imidazolium ions.

Examples of the quaternary ammonium cation (tetraalkylammonium ion) formed by quaternizing nitrogen of trialkylamine include the following.
Tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, N, N, N-triethyl-N-methylammonium, tetraethylammonium, trimethyl-n-propylammonium, trimethylisopropylammonium, ethyldimethyl-n-propylammonium, ethyldimethylisopropyl Ammonium, diethylmethyl-n-propylammonium, diethylmethylisopropylammonium, dimethyldi-n-propylammonium, dimethyl-n-propylisopropylammonium, dimethyldiisopropylammonium, triethyl-n-propylammonium, n-butyltrimethylammonium, isobutyltrimethylammonium , T-butyltrimethylammonium, trie Ruisopropylammonium, ethylmethyldi-n-propylammonium, ethylmethyl-n-propylisopropylammonium, ethylmethyldiisopropylammonium, n-butylethyldimethylammonium, isobutylethyldimethylammonium, t-butylethyldimethylammonium, diethyldi-n-propylammonium , Diethyl-n-propylisopropylammonium, diethyldiisopropylammonium, methyltri-n-propylammonium, methyldi-n-propylisopropylammonium, methyl-n-propyldiisopropylammonium, n-butyltriethylammonium, isobutyltriethylammonium, t-butyl Triethylammonium, di-n-butyldimethylammonium , Diisobutyl dimethyl ammonium, di -t- butyl dimethyl ammonium, n- butyl isobutyl dimethyl ammonium, n- butyl -t- butyl dimethyl ammonium, isobutyl -t- butyl dimethyl ammonium.

Examples of the quaternary ammonium cation (pyrrolidinium ion) formed by quaternizing the nitrogen of the pyrrolidine ring include the following.
N, N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, N, N-diethylpyrrolidinium, 1,1,2-trimethylpyrrolidinium, 1,1,3-trimethylpyrrolidinium 1-ethyl-1,2-dimethylpyrrolidinium, 1-ethyl-1,3-dimethylpyrrolidinium, 2-ethyl-1,1-dimethylpyrrolidinium, 3-ethyl-1,1-dimethylpyrrole Dinium, 1,1-diethyl-2-methylpyrrolidinium, 1,1-diethyl-3-methylpyrrolidinium, 1,2-diethyl-1-methylpyrrolidinium, 1,3-diethyl-1- Methylpyrrolidinium, 1,1,2-triethylpyrrolidinium, 1,1,3-triethylpyrrolidinium, 1,1,2,2-tetramethylpyrrolidinium, 1,1,2,3- Tramethylpyrrolidinium, 1,1,2,4-tetramethylpyrrolidinium, 1,1,2,5-tetramethylpyrrolidinium, 1,1,3,4-tetramethylpyrrolidinium, 1, 1,3,3-tetramethylpyrrolidinium, 2-ethyl-1,1,2-trimethylpyrrolidinium, 2-ethyl-1,1,3-trimethylpyrrolidinium, 3-ethyl-1,1, 2-trimethylpyrrolidinium, 3-ethyl-1,1,3-trimethylpyrrolidinium, 2-ethyl-1,1,4-trimethylpyrrolidinium, 4-ethyl-1,1,2-trimethylpyrrolidi Ni, 2-ethyl-1,1,5-trimethylpyrrolidinium, 3-ethyl-1,1,4-trimethylpyrrolidinium, 1-ethyl-1,2,2-trimethylpyrrolidinium, 1-ethyl − , 2,3-trimethylpyrrolidinium, 1-ethyl-1,3,3-trimethylpyrrolidinium, 1-ethyl-1,2,4-trimethylpyrrolidinium, 1-ethyl-1,2,5- Trimethylpyrrolidinium, 1-ethyl-1,3,4-trimethylpyrrolidinium, 2,2-diethyl-1,1-dimethylpyrrolidinium, 2,3-diethyl-1,1-dimethylpyrrolidinium, 3,3-diethyl-1,1-dimethylpyrrolidinium, 2,4-diethyl-1,1-dimethylpyrrolidinium, 2,5-diethyl-1,1-dimethylpyrrolidinium, 3,4-diethyl -1,1-dimethylpyrrolidinium, 1,2-diethyl-1,2-dimethylpyrrolidinium, 1,2-diethyl-1,3-dimethylpyrrolidinium, 1,3-diethyl-1,2- Jime Tilpyrrolidinium, 1,3-diethyl-1,3-dimethylpyrrolidinium, 1,2-diethyl-1,4-dimethylpyrrolidinium, 1,4-diethyl-1,2-dimethylpyrrolidinium, 1,2-diethyl-1,5-dimethylpyrrolidinium, 1,3-diethyl-1,4-dimethylpyrrolidinium, 1,1,2,2,3-pentamethylpyrrolidinium, 1,1, 2,2,4-pentamethylpyrrolidinium, 1,1,2,2,5-pentamethylpyrrolidinium, 1,1,2,3,4-pentamethylpyrrolidinium, 1,1,2, 3,5-pentamethylpyrrolidinium, 1,1,3,3,4-pentamethylpyrrolidinium, 1,1,3,3,5-pentamethylpyrrolidinium, 1-ethyl-1,2, 2,3-tetramethylpyrrolidinium, 1- Til-1,2,2,4-tetramethylpyrrolidinium, 1-ethyl-1,2,2,5-tetramethylpyrrolidinium, 1-ethyl-1,2,3,4-tetramethylpyrrolidinium 1-ethyl-1,2,3,4-tetramethylpyrrolidinium, 1-ethyl-1,2,4,5-tetramethylpyrrolidinium, 1-ethyl-1,3,4,4- Tetramethylpyrrolidinium, 1-ethyl-1,3,3,5-tetramethylpyrrolidinium, 2-ethyl-1,1,2,3-tetramethylpyrrolidinium, 2-ethyl-1,1, 2,4-tetramethylpyrrolidinium, 2-ethyl-1,1,2,5-tetramethylpyrrolidinium, 2-ethyl-1,1,3,3-tetramethylpyrrolidinium, 2-ethyl- 1,1,3,4-tetramethylpyrrolidinium 2-ethyl-1,1,3,5-tetramethylpyrrolidinium, 2-ethyl-1,1,4,4-tetramethylpyrrolidinium, 2-ethyl-1,1,4,5-tetramethyl Pyrrolidinium, 2-ethyl-1,1,5,5-tetramethylpyrrolidinium, 3-ethyl-1,1,2,2-tetramethylpyrrolidinium, 3-ethyl-1,1,2, 3-tetramethylpyrrolidinium, 3-ethyl-1,1,2,4-tetramethylpyrrolidinium, 3-ethyl-1,1,2,5-tetramethylpyrrolidinium, 3-ethyl-1, 1,3,4-tetramethylpyrrolidinium, 3-ethyl-1,1,4,4-tetramethylpyrrolidinium, 3-ethyl-1,1,4,5-tetramethylpyrrolidinium, 1, 1,2,2,3,3-hexamethylpyrrolidinium 1,1,2,2,3,4-hexamethylpyrrolidinium, 1,1,2,2,3,5-hexamethylpyrrolidinium, 1,1,2,2,4,4-hexa Methylpyrrolidinium, 1,1,2,2,4,5-hexamethylpyrrolidinium, 1,1,2,2,5,5-hexamethylpyrrolidinium, 1,1,2,3,3 , 4-hexamethylpyrrolidinium, 1,1,2,3,3,5-hexamethylpyrrolidinium, 1,1,2,3,4,4-hexamethylpyrrolidinium, 1,1,2 3,5,5-hexamethylpyrrolidinium, 1,1,2,3,4,5-hexamethylpyrrolidinium and the like.

  Examples of the spiro quaternary ammonium cation include the following. Spiro- (1,1 ′)-bipyrrolidinium, 2-methylspiro- (1,1 ′)-bipyrrolidinium, 3-methylspiro- (1,1 ′)-bipyrrolidinium, 2,2-dimethylspiro- (1,1 ′) -Bipyrrolidinium, 2,3-dimethylspiro- (1,1 ')-bipyrrolidinium, 3,3-dimethylspiro- (1,1')-bipyrrolidinium, 2,4-dimethylspiro- (1,1 ')-bipyrrolidinium 2,5-dimethylspiro- (1,1 ′)-bipyrrolidinium, 3,4-dimethylspiro- (1,1 ′)-bipyrrolidinium, 2,2′-dimethyl-spiro- (1,1 ′)-bipyrrolidinium 2,3′-dimethylspiro- (1,1 ′)-bipyrrolidinium, 2,4′-dimethylspiro- (1,1 ′)-bipyrrolidinium, 2,5′-dimethyl Ruspiro- (1,1 ′)-bipyrrolidinium, 2,3,4-trimethylspiro- (1,1 ′)-bipyrrolidinium, 2,3,5-trimethylspiro- (1,1 ′)-bipyrrolidinium, 3,4 , 5-Trimethylspiro- (1,1 ′)-bipyrrolidinium, 2,3,2′-trimethylspiro- (1,1 ′)-bipyrrolidinium, 2,3,3′-trimethylspiro- (1,1 ′) -Bipyrrolidinium, 2,3,4'-trimethylspiro- (1,1 ')-bipyrrolidinium, 2,3,5'-trimethylspiro- (1,1')-bipyrrolidinium, 3,4,2'-trimethylspiro -(1,1 ')-bipyrrolidinium, 3,4,3'-trimethylspiro- (1,1')-bipyrrolidinium, 3,4,4'-trimethylspiro- (1,1 ')-bipyro Jiniumu, 3,4,5'- trimethyl spiro - (1,1 ') - bipyrrolidinium, 2- Echirusupiro - (1,1' - like bipyrrolidinium).

Examples of the quaternary ammonium cation (morpholinium ion) formed by quaternizing the morpholine ring nitrogen include the following.
N, N-dimethylmorpholinium, N-ethyl-N-methylmorpholinium, N, N-diethylmorpholinium, 3,4,4-trimethylmorpholinium, 2,4,4-trimethylmorpholinium 3-ethyl-4,4-dimethylmorpholinium, 2-ethyl-4,4-dimethylmorpholinium, 3,4-dimethyl-4-ethylmorpholinium, 2,4-dimethyl-4-ethylmol Folinium, 3-methyl-4,4-diethylmorpholinium, 2-methyl-4,4-diethylmorpholinium, 3,4-diethyl-4-methylmorpholinium, 2,4-diethyl-4- Methylmorpholinium, 3,4,4-triethylmorpholinium, 2,4,4-triethylmorpholinium, 3,3,4,4-tetramethylmorpholinium, 2,3,4,4- Tramethylmorpholinium, 2,4,4,5-tetramethylmorpholinium, 3,4,4,5-tetramethylmorpholinium, 2,2,4,4-tetramethylmorpholinium, 2, 4,4,6-tetramethylmorpholinium, 2,4,4-trimethyl-3-ethylmorpholinium, 2-ethyl-3,4,4-trimethylmorpholinium, 2,4,4-trimethyl- 5-ethylmorpholinium, 2-ethyl-4,4,5-trimethylmorpholinium, 3-ethyl-4,4,5-trimethylmorpholinium, 2-ethyl-4,4,6-trimethylmorpholine Ni, 2,3-dimethyl-4,4-diethylmorpholinium, 2,5-dimethyl-4,4-diethylmorpholinium, 3,5-dimethyl-4,4-diethylmorpholinium, 2,6 -Jimee -4,4-diethylmorpholinium, 2,4-dimethyl-3,4-diethylmorpholinium, 2,4-diethyl-3,4-dimethylmorpholinium, 2,4-dimethyl-4,5 -Diethylmorpholinium, 2,4-diethyl-4,5-dimethylmorpholinium, 3,4-diethyl-4,5-dimethylmorpholinium, 2,4-diethyl-4,6-dimethylmorpholinium 2,3-diethyl-4,4-dimethylmorpholinium, 2,5-diethyl-4,4-dimethylmorpholinium, 3,5-diethyl-4,4-dimethylmorpholinium, 2,6- Diethyl-4,4-dimethylmorpholinium, 2,3,4,4,6-pentamethylmorpholinium, 2,3,4,4,5-pentamethylmorpholinium, 2,4,4,6 -Tetramethyl-3- Ethylmorpholinium, 2,4,4,5-tetramethyl-3-ethylmorpholinium, 2-ethyl-3,4,4,6-tetramethylmorpholinium, 2-ethyl-3,4,4 , 5-tetramethylmorpholinium, 2,3,4,4,5,6-hexamethylmorpholinium and the like.

Examples of the quaternary ammonium cation (imidazolinium ion) formed by quaternizing the nitrogen of the imidazoline ring include the following.
N, N'-dimethylimidazolinium, N-ethyl-N'-methylimidazolinium, N, N'-diethylimidazolinium, 1,2,3-trimethylimidazolinium, 1,3,4-trimethyl Imidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1-ethyl-3,4-dimethylimidazolinium, 1-ethyl-3,5-dimethylimidazolinium, 2-ethyl-1,3 -Dimethylimidazolinium, 4-ethyl-1,3-dimethylimidazolinium, 1,2-diethyl-3-methylimidazolinium, 1,4-diethyl-3-methylimidazolinium, 1,5-diethyl -3-methylimidazolinium, 1,3-diethyl-2-methylimidazolinium, 1,3-diethyl-4-methylimidazolinium, 1,2,3- Liethylimidazolinium, 1,3,4-triethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1-ethyl-2,3,4-trimethylimidazolinium, 1-ethyl- 2,3,5-trimethylimidazolinium, 1-ethyl-3,4,5-trimethylimidazolinium, 2-ethyl-1,3,4-trimethylimidazolinium, 4-ethyl-1,2,3 -Trimethylimidazolinium, 1,2-diethyl-3,4-dimethylimidazolinium, 1,3-diethyl-2,4-dimethylimidazolinium, 1,4-diethyl-2,3-dimethylimidazolinium 2,4-diethyl-1,3-dimethylimidazolinium, 4,5-diethyl-1,3-dimethylimidazolinium, 1,2,3-triethyl-4-methyl Imidazolinium, 1,2,4-triethyl-3-methylimidazolinium, 1,2,5-triethyl-3-methylimidazolinium, 1,3,4-triethyl-2-methylimidazolinium, 1 3,4-triethyl-5-methylimidazolinium, 1,4,5-triethyl-3-methylimidazolinium, 1,2,3,4,5-pentamethylimidazolinium and the like.

The quaternary ammonium cation (pyrimidinium ion) obtained by quaternizing the nitrogen of the tetrahydropyrimidine ring includes the following.
N, N'-dimethyltetrahydropyrimidinium, N-ethyl-N'-methyltetrahydropyrimidinium, N, N'-diethyltetrahydropyrimidinium, 1,2,3-trimethyltetrahydropyrimidinium, 1,3 , 4-trimethyltetrahydropyrimidinium, 1,3,5-trimethyltetrahydropyrimidinium, 1-ethyl-2,3-dimethyltetrahydropyrimidinium, 1-ethyl-3,4-dimethyltetrahydropyrimidinium, -Ethyl-3,5-dimethyltetrahydropyrimidinium, 1-ethyl-3,6-dimethyltetrahydropyrimidinium, 2-ethyl-1,3-dimethyltetrahydropyrimidinium, 4-ethyl-1,3-dimethyl Tetrahydropyrimidinium, 5-ethyl-1,3-dimethyltetrahi Lopyrimidinium, 1,2,3,4-tetramethyltetrahydropyrimidinium, 1,2,3,5-tetramethyltetrahydropyrimidinium, 1-ethyl-2,3,4-trimethyltetrahydropyrimidinium, 1- Ethyl-2,3,5-trimethyltetrahydropyrimidinium, 1-ethyl-2,3,6-trimethyltetrahydropyrimidinium, 2-ethyl-1,3,4-trimethyltetrahydropyrimidinium, 2-ethyl- 1,3,5-trimethyltetrahydropyrimidinium, 4-ethyl-1,2,3-trimethyltetrahydropyrimidinium, 4-ethyl-1,3,5-trimethyltetrahydropyrimidinium, 4-ethyl-1, 3,6-trimethyltetrahydropyrimidinium, 5-ethyl-1,2,3-trimethylteto Hydropyrimidinium, 5-ethyl-1,3,4-trimethyltetrahydropyrimidinium, 1,2-diethyl-3,4-dimethyltetrahydropyrimidinium, 1,2-diethyl-3,5-dimethyltetrahydropyrim Midinium, 1,2-diethyl-3,6-dimethyltetrahydropyrimidinium, 1,3-diethyl-2,4-dimethyltetrahydropyrimidinium, 1,3-diethyl-2,5-dimethyltetrahydropyrimidinium 1,4-diethyl-2,3-dimethyltetrahydropyrimidinium, 1,4-diethyl-3,5-dimethyltetrahydropyrimidinium, 1,4-diethyl-3,6-dimethyltetrahydropyrimidinium, , 5-Diethyl-2,3-dimethyltetrahydropyrimidinium, 1,5-diethyl-3,4 -Dimethyltetrahydropyrimidinium, 1,5-diethyl-3,6-dimethyltetrahydropyrimidinium, 2,4-diethyl-1,3-dimethyltetrahydropyrimidinium, 2,5-diethyl-1,3-dimethyl Tetrahydropyrimidinium, 4,5-diethyl-1,3-dimethyltetrahydropyrimidinium, 4,6-diethyl-1,3-dimethyltetrahydropyrimidinium, 1,2,3,4,5-pentamethyltetrahydro Pyrimidinium, 1,2,3,4,6-pentamethyltetrahydropyrimidinium, 1,2,3,4,5,6-hexamethyltetrahydropyrimidinium, 5-methyl-1,5-diazabicyclo [ 4.3.0] -5-nonenium, 5-ethyl-1,5-diazabicyclo [4.3.0] -5-nonenium, 5 Methyl-1,5-diazabicyclo [5.4.0] -5-Undeseniumu, such as 5-ethyl-1,5-diazabicyclo [5.4.0] -5-Undeseniumu.

Examples of the quaternary ammonium cation (piperazinium ion) formed by quaternizing the nitrogen of the piperazine ring include the following.
N, N, N ′, N′-tetramethylpiperazinium, N-ethyl-N, N ′, N′-trimethylpiperazinium, N, N-diethyl-N ′, N′-dimethylpiperazinium, N, N, N′-triethyl-N′-methylpiperazinium, N, N, N ′, N′-tetraethylpiperazinium, 1,1,2,4,4-pentamethylpiperazinium, 1, 1,3,4,4-pentamethylpiperazinium, 1,1,2,3,4,4-hexamethylpiperazinium, 1,1,2,4,4,5-hexamethylpiperazinium, 1,1,2,4,4,6-hexamethylpiperazinium, 1,1,3,4,4,5-hexamethylpiperazinium, 1-ethyl-1,2,4,4-tetramethyl Piperazinium, 1-ethyl-1,3,4,4-tetramethylpiperazi , 2-ethyl-1,1,4,4-tetramethylpiperazinium, 1-ethyl-1,2,4,4-tetramethylpiperazinium, 1-ethyl-1,3,4,4- Tetramethylpiperazinium, 1,1-diethyl-2,4,4-trimethylpiperazinium, 1,4-diethyl-1,2,4-trimethylpiperazinium, 1,2-diethyl-1,4, 4-trimethylpiperazinium, 1,3-diethyl-1,4,4-trimethylpiperazinium and the like.

Examples of the quaternary ammonium cation (piperidinium ion) formed by quaternizing the nitrogen of the piperidine ring include the following.
N, N-dimethylpiperidinium, N-ethyl-N-methylpiperidinium, N, N-diethylpiperidinium, 1,1,2-trimethylpiperidinium, 1,1,3-trimethylpiperidinium 1,1,4-trimethylpiperidinium, 1,2,2-tetramethylpiperidinium, 1,1,2,3-tetramethylpiperidinium, 1,1,2,4-tetramethylpiperidi 1,1,2,5-tetramethylpiperidinium, 1,1,2,6-tetramethylpiperidinium, 1,1,3,3-tetramethylpiperidinium, 1,1,3 4-tetramethylpiperidinium, 1,1,3,5-tetramethylpiperidinium, 1-ethyl-1,2-dimethylpiperidinium, 1-ethyl-1,3-dimethylpiperidinium, 1- Ethyl-1 4-dimethylpiperidinium, 1-ethyl-1,2,3-trimethylpiperidinium, 1-ethyl-1,2,4-trimethylpiperidinium, 1-ethyl-1,2,5-trimethylpiperidi 1-ethyl-1,3,4-trimethylpiperidinium, 1-ethyl-1,3,4-trimethylpiperidinium, 1-ethyl-1,3,5-trimethylpiperidinium, 1,1 -Diethyl-2-methylpiperidinium, 1,1-diethyl-3-methylpiperidinium, 1,1-diethyl-4-methylpiperidinium, 1,1-diethyl-2,3-dimethylpiperidinium 1,1-diethyl-2,4-dimethylpiperidinium, 1,1-diethyl-2,5-dimethylpiperidinium, 1,1-diethyl-2,6-dimethylpiperidinium, -Diethyl-3,4-dimethylpiperidinium, 1,1-diethyl-3,5-dimethylpiperidinium, 2-ethyl-1,1,3-trimethylpiperidinium, 2-ethyl-1,1, 4-trimethylpiperidinium, 2-ethyl-1,1,5-trimethylpiperidinium, 2-ethyl-1,1,6-trimethylpiperidinium, 3-ethyl-1,1,2-trimethylpiperidi Ni, 3-ethyl-1,1,4-trimethylpiperidinium, 3-ethyl-1,1,5-trimethylpiperidinium, 3-ethyl-1,1,6-trimethylpiperidinium, 4-ethyl -1,1,2-trimethylpiperidinium, 4-ethyl-1,1,3-trimethylpiperidinium, 1,2-diethyl-1,3-dimethylpiperidinium, 1-ethyl-1,2, 4 -Trimethylpiperidinium, 1,2-diethyl-1,5-dimethylpiperidinium, 1,2-diethyl-1,6-dimethylpiperidinium, 1,3-diethyl-1,5-dimethylpiperidinium 1,3-diethyl-1,4-dimethylpiperidinium, 1,3-diethyl-1,6-dimethylpiperidinium, 1,4-diethyl-1,2-dimethylpiperidinium, 1,4- Diethyl-1,3-dimethylpiperidinium, 1,1,2-triethyl-3-methylpiperidinium, 1,1,2-triethyl-4-methylpiperidinium, 1,1,2-triethyl-5 -Methylpiperidinium, 1,1,2-triethyl-6-methylpiperidinium, 1,1,3-triethyl-2-methylpiperidinium, 1,1,3-triethyl-4-methylpipe Dinium, 1,1,3-triethyl-5-methylpiperidinium, 1,1,3-triethyl-6-methylpiperidinium, 1,1,4-triethyl-2-methylpiperidinium, 1,1 , 4-triethyl-3-methylpiperidinium, 2-ethyl-1,1-dimethylpiperidinium, 3-ethyl-1,1-dimethylpiperidinium, 4-ethyl-1,1-dimethylpiperidinium 2,3-diethyl-1,1-dimethylpiperidinium, 2,4-diethyl-1,1-dimethylpiperidinium, 2,5-diethyl-1,1-dimethylpiperidinium, 2,6- Diethyl-1,1-dimethylpiperidinium, 3,4-diethyl-1,1-dimethylpiperidinium, 3,5-diethyl-1,1-dimethylpiperidinium, 1,2-diethyl-1- Tilpiperidinium, 1,3-diethyl-1-methylpiperidinium, 1,4-diethyl-1-methylpiperidinium, 1,2,3-triethyl-1-methylpiperidinium, 1,2, 4-triethyl-1-methylpiperidinium, 1,2,5-triethyl-1-methylpiperidinium, 1,2,6-triethyl-1-methylpiperidinium, 1,3,4-triethyl-1 -Methylpiperidinium, 1,3,5-triethyl-1-methylpiperidinium, 1,1,2-triethylpiperidinium, 1,1,4-triethylpiperidinium, 1,1,2,3 -Tetraethylpiperidinium, 1,1,2,4-tetraethylpiperidinium, 1,1,2,5-tetraethylpiperidinium, 1,1,2,6-tetraethylpiperidinium, 1,1 , 3,4-tetramethylpiperidinium, 1,1,3,5-tetraethylpiperidinium, and the like.

Examples of the quaternary ammonium cation (pyridinium ion) formed by quaternizing nitrogen of the pyridine ring include the following.
N-methylpyridinium, N-ethylpyridinium, 1,2-dimethylpyridinium, 1,3-dimethylpyridinium, 1,4-dimethylpyridinium, 1-ethyl-2-methylpyridinium, 2-ethyl-1-methylpyridinium, 1 -Ethyl-3-methylpyridinium, 3-ethyl-1-methylpyridinium, 1-ethyl-4-methylpyridinium, 4-ethyl-1-methylpyridinium, 1,2-diethylpyridinium, 1,3-diethylpyridinium, 1 , 4-diethylpyridinium, 1,2,3-trimethylpyridinium, 1,2,4-trimethylpyridinium, 1,3,4-trimethylpyridinium, 1,3,5-trimethylpyridinium, 1,2,5-trimethylpyridinium 1,2,6-trimethylpyridinium, 1-e Ru-2,3-dimethylpyridinium, 1-ethyl-2,4-dimethylpyridinium, 1-ethyl-2,5-dimethylpyridinium, 1-ethyl-2,6-dimethylpyridinium, 1-ethyl-3,4- Dimethylpyridinium, 1-ethyl-3,5-dimethylpyridinium, 2-ethyl-1,3-dimethylpyridinium, 2-ethyl-1,4-dimethylpyridinium, 2-ethyl-1,5-dimethylpyridinium, 2-ethyl -1,6-dimethylpyridinium, 3-ethyl-1,2-dimethylpyridinium, 3-ethyl-1,4-dimethylpyridinium, 3-ethyl-1,5-dimethylpyridinium, 3-ethyl-1,6-dimethyl Pyridinium, 4-ethyl-1,2-dimethylpyridinium, 4-ethyl-1,3-dimethylpyridinium, , 2-Diethyl-3-methylpyridinium, 1,2-diethyl-4-methylpyridinium, 1,2-diethyl-5-methylpyridinium, 1,2-diethyl-6-methylpyridinium, 1,3-diethyl-2 -Methylpyridinium, 1,3-diethyl-4-methylpyridinium, 1,3-diethyl-5-methylpyridinium, 1,3-diethyl-6-methylpyridinium, 1,4-diethyl-2-methylpyridinium, 1, 4-diethyl-3-methylpyridinium, 2,3-diethyl-1-methylpyridinium, 2,4-diethyl-1-methylpyridinium, 2,5-diethyl-1-methylpyridinium, 2,6-diethyl-1- Methylpyridinium, 3,4-diethyl-1-methylpyridinium, 3,5-diethyl-1-methylpyridinium 1,2,3,4,5-pentamethylpyridinium, 1,2,3,4,6-pentamethylpyridinium, 1,2,3,5,6-pentamethylpyridinium, 1,2,3 4,5,6-hexamethylpyridinium and the like.

Examples of the quaternary ammonium cation (imidazolium ion) formed by quaternizing nitrogen of the imidazole ring include the following.
N, N'-dimethylimidazolium, N-ethyl-N'-methylimidazolium, N, N'-diethylimidazolium, 1,2,3-trimethylimidazolium, 1,3,4-trimethylimidazolium, 1 -Ethyl-2,3-dimethylimidazolium, 1-ethyl-3,4-dimethylimidazolium, 1-ethyl-3,5-dimethylimidazolium, 2-ethyl-1,3-dimethylimidazolium, 4-ethyl -1,3-dimethylimidazolium, 1,2-diethyl-3-methylimidazolium, 1,4-diethyl-3-methylimidazolium, 1,5-diethyl-3-methylimidazolium, 1,3-diethyl 2-methylimidazolium, 1,3-diethyl-4-methylimidazolium, 1,2,3-triethylimidazolium, 1, , 4-triethylimidazolium, 1,2,3,4-tetramethylimidazolium, 1-ethyl-2,3,4-trimethylimidazolium, 1-ethyl-2,3,5-trimethylimidazolium, 1- Ethyl-3,4,5-trimethylimidazolium, 2-ethyl-1,3,4-trimethylimidazolium, 4-ethyl-1,2,3-trimethylimidazolium, 1,2-diethyl-3,4- Dimethylimidazolium, 1,3-diethyl-2,4-dimethylimidazolium, 1,4-diethyl-2,3-dimethylimidazolium, 1,4-diethyl-2,5-dimethylimidazolium, 2,4- Diethyl-1,3-dimethylimidazolium, 4,5-diethyl-1,3-dimethylimidazolium, 1,2,3-triethyl-4-methylimidazole Zolium, 1,2,4-triethyl-3-methylimidazolium, 1,2,5-triethyl-3-methylimidazolium, 1,3,4-triethyl-2-methylimidazolium, 1,3,4 Triethyl-5-methylimidazolium, 1,4,5-triethyl-3-methylimidazolium, 1,2,3,4,5-pentamethylimidazolium and the like.

  Among them, the quaternary ammonium cation is preferably a tetraalkylammonium ion or a pyrrolidinium ion. The tetraalkylammonium ion is more preferably N, N, N-triethyl-N-methylammonium. The pyrrolidinium ion is more preferably N-ethyl-N-methylpyrrolidinium. Among them, the quaternary ammonium cation is particularly preferably N-ethyl-N-methylpyrrolidinium.

A commercially available compound can be used for the quaternary ammonium salt represented by the general formula (I). In other instances, well-known methods, for example, tertiary amine and the halide salt of the quaternary ammonium obtained by reacting with an alkyl halide of the general formula in (I) X ^- consists in represented counterion It can also be produced by a method in which an acid or an alkali metal salt thereof is mixed and reacted (salt exchange) in an arbitrary solvent.

  The electrolyte solution of the present invention is a component other than the above essential components (non-aqueous solvent, quaternary ammonium salt represented by formula (I), and alkali metal cation) as long as the effects of the present invention are exhibited. 1 type or 2 types or more may be included.

An electric double layer capacitor using the non-aqueous electrolyte as an electrolyte is also included in the present invention.
The electric double layer capacitor of the present invention only needs to use the above non-aqueous electrolyte as the electrolyte, and the manufacturing method thereof is not particularly limited. The electric double layer capacitor of the present invention has excellent durability in which a decrease in capacity (capacity deterioration) and an increase in resistance are reduced by using the non-aqueous electrolyte described above.

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
The measurement of the alkali metal cation concentration in the electrolytic solution and the evaluation of the characteristics of the electric double layer capacitor produced using this electrolytic solution were performed by the following methods.

Determination of alkali metal cations Determination of potassium ions:
Measurements were performed using ion chromatography.
Column: Dionex Ion Pac CS14 φ4 × 250mm (Japan Dionex)
Detection method: Conductivity suppressor: CSRS300 (product name, Nippon Dionex)
Suppressor current value: 35 mA
Mobile phase: 0.010 M methanesulfonic acid solution regenerating solution: ultrapure water (2 mL / min)
Mobile phase flow rate: 1.0 mL / min Column temperature: 30 ° C.
Cell temperature: 35 ° C
Sample injection volume: 25 μL
Measurement method: Analyze standard product (0.1 ppm potassium solution) and sample solution (approx. 500 mg sample up to 50 ml with ultrapure water) and calculate the content using the following formula based on the peak obtained. did.

Potassium ion (K ⁺ ) content (ppm) = K in sample solution ⁺ peak area × 0.1 × 50 / sampled amount (mg) / K ⁺ peak area in standard solution × 1000

Na ⁺ and other alkali metal cations were analyzed by changing the standard to the target compound.

Characteristic evaluation of electric double layer capacitor:
(Capacitor manufacturing method)
An element (3 cm × 5 cm: 5 layers) is manufactured using the following materials, vacuum-dried at 180 ° C. for 15 hours, and then impregnated with an electrolytic solution (electrolytic solution amount 0.097 cc / F) to be a laminate cell (Electric double layer capacitor) was produced. The produced electric double layer capacitor was subjected to an aging treatment for 24 hours with 2.7 V applied at room temperature, and the initial characteristics of each were measured.
Electrode: Sheet electrode manufactured by Japan Gore-Tex Co., Ltd. Electrolytic paper (separator): TF4050 manufactured by Nippon Kogyo Paper Industries
Electrolyte: each electrolyte prepared in Examples 1 to 5 and Comparative Examples 1 to 4

  With respect to the electric double layer capacitor, an initial capacity and an internal resistance when a voltage of 2.7 V was applied were measured. Further, the capacity after storage for 2000 hours at 60 ° C. while applying a voltage of 2.7 V was measured, and the capacity deterioration rate from the initial capacity was calculated. The internal resistance was measured by an AC two-terminal method at a frequency of 1 kHz.

  The methods for preparing the electrolyte solutions used in the examples and comparative examples are as follows. The propylene carbonate used in the examples and comparative examples is high-purity propylene carbonate (purity 99.99%) that has been precision distilled.

Production Example 1:
N-ethyl-N-methylpyrrolidinium tetrafluoroborate was produced according to the method described in Example 1 of JP-B-8-31401.

Production Example 2:
After 1000 g of N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 1 was dissolved in water containing 0.5 mg of NaBF ₄ and 20 mg of KBF ₄ , the contents were concentrated under reduced pressure. When the slurry became a normal pressure, 2000 g of isopropanol was added and recrystallized to obtain white crystals of N-ethyl-N-methylpyrrolidinium tetrafluoroborate.

Production Example 3:
The white crystals of N-ethyl-N-methylpyrrolidinium tetra were prepared in the same manner as in Production Example 2 except that NaBF ₄ 0.5 mg and KBF ₄ 20 mg were changed to NaBF ₄ 20 mg and KBF ₄ 0.3 mg, respectively. Fluoroborate was obtained.

Production Example 4:
Except for changing 1-ethyl-1-methylpyrrolidinium bromide to N, N, N-triethyl-N-methylammonium bromide, according to the method described in Example 1 of JP-B-8-31401, N, N, N-triethyl-N-methylammonium tetrafluoroborate was prepared.

Production Example 5:
Similar to Production Example 2, except that N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 4 was used instead of N-ethyl-N-methylpyrrolidinium tetrafluoroborate. The operation gave white crystals of N, N, N-triethyl-N-methylammonium tetrafluoroborate.

Production Example 6:
Similar to Production Example 3 except that N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 4 was used instead of N-ethyl-N-methylpyrrolidinium tetrafluoroborate. The operation gave white crystals of N, N, N-triethyl-N-methylammonium tetrafluoroborate.

Comparative Example 1:
N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 1 as an electrolyte in high-purity propylene carbonate at room temperature in a dry nitrogen atmosphere with a dew point of −40 ° C. is 1.5 mol / L. An electrolyte solution was prepared by dissolving in the solution. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Comparative Example 2:
N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 2 as an electrolyte in high-purity propylene carbonate at room temperature in a dry nitrogen atmosphere having a dew point of −40 ° C. is 1.5 mol / L. An electrolyte solution was prepared by dissolving in the solution. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Example 1:
100 g of N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 2 was put into 100 g of dichloromethane and dissolved at 25 ° C., and then filtered through a 0.45 μm membrane filter. The obtained filtrate was concentrated, crystallized by adding isopropyl alcohol to the concentrated residue, and cooled to 5 ° C. The obtained crystals were collected by filtration, washed with 5 ° C. isopropyl alcohol, and then dried under reduced pressure. An electrolytic solution was obtained in the same manner as in Comparative Example 1 except that the crystal thus obtained was used. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Example 2:
100 g of N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 2 was put into 100 g of dichloromethane and dissolved at 5 ° C., and then filtered through a 0.45 μm membrane filter. The obtained filtrate was concentrated, crystallized by adding isopropyl alcohol to the concentrated residue, and cooled to 5 ° C. The obtained crystals were collected by filtration, washed with 5 ° C. isopropyl alcohol, and then dried under reduced pressure. An electrolytic solution was obtained in the same manner as in Comparative Example 1 except that the crystal thus obtained was used as the electrolyte. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Comparative Example 3:
N-ethyl-N-methylpyrrolidinium tetrafluoroborate produced in Production Example 3 as an electrolyte in high-purity propylene carbonate at room temperature in a dry nitrogen atmosphere having a dew point of −40 ° C. is 1.5 mol / L. An electrolyte solution was prepared by dissolving in the solution. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Example 3:
100 g of the same N-ethyl-N-methylpyrrolidinium tetrafluoroborate used in Production Example 3 was put into 100 g of dichloromethane and dissolved at 5 ° C., and this was filtered with a 0.45 μm membrane filter. Filtered. The obtained filtrate was concentrated, crystallized by adding isopropyl alcohol to the concentrated residue, and cooled to 5 ° C. The obtained crystals were collected by filtration, washed with 5 ° C. isopropyl alcohol, and then dried under reduced pressure. An electrolytic solution was obtained in the same manner as in Comparative Example 2 except that the crystal thus obtained was used as the electrolyte. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Comparative Example 4:
N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 5 as an electrolyte in high-purity propylene carbonate at 1.5 mol / L in a dry nitrogen atmosphere at a dew point of −40 ° C. at room temperature It melt | dissolved so that electrolyte solution might be prepared. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Example 4:
100 g of N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 5 was added to 100 g of dichloromethane, dissolved at 5 ° C., and then filtered through a 0.45 μm membrane filter. did. The obtained filtrate was concentrated, crystallized by adding isopropyl alcohol to the concentrated residue, and cooled to 5 ° C. The obtained crystals were collected by filtration, washed with 5 ° C. isopropyl alcohol, and then dried under reduced pressure. An electrolytic solution was obtained in the same manner as in Comparative Example 4 except that the crystal thus obtained was used as the electrolyte. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Comparative Example 5:
N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 6 as electrolyte in high-purity propylene carbonate at 1.5 mol / L at room temperature in a dry nitrogen atmosphere with a dew point of −40 ° C. It melt | dissolved so that electrolyte solution might be prepared. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Example 5:
100 g of N, N, N-triethyl-N-methylammonium tetrafluoroborate produced in Production Example 6 was put into 100 g of dichloromethane and dissolved at 5 ° C., and then filtered through a 0.45 μm membrane filter. did. The obtained filtrate was concentrated, crystallized by adding isopropyl alcohol to the concentrated residue, and cooled to 5 ° C. The obtained crystals were collected by filtration, washed with 5 ° C. isopropyl alcohol, and then dried under reduced pressure. An electrolytic solution was obtained in the same manner as in Comparative Example 5 except that the crystal thus obtained was used as the electrolyte. Table 1 shows the characteristics of the electric double layer capacitor manufactured using the same.

Claims (10)

The following general formula (I) as an electrolyte in a non-aqueous solvent:
Q ⁺ X ⁻ (I)
(In the above formula, Q ⁺ represents a quaternary ammonium cation, and X ⁻ represents PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , SbF ₆ ⁻ and RfSO ₃ ^−. (Wherein Rf represents a counter ion selected from the group consisting of a C1-C8 fluoroalkyl group) dissolved in a quaternary ammonium salt (excluding spiro-type quaternary ammonium tetrafluoroborate) A non-aqueous electrolyte for an electric double layer capacitor,
The quaternary ammonium cation is tetraalkylammonium;
The non-aqueous electrolyte contains 3.1 to 11.3 ppm of an alkali metal cation. The following general formula (I) as an electrolyte in a non-aqueous solvent:
Q ⁺ X ⁻     (I)
(In the above formula, Q ⁺ Represents a quaternary ammonium cation, X ⁻ Is PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , SbF ₆ ⁻ And RfSO ₃ ^- (Wherein Rf represents a counter ion selected from the group consisting of a C1-C8 fluoroalkyl group) dissolved in a quaternary ammonium salt (excluding spiro-type quaternary ammonium tetrafluoroborate) A non-aqueous electrolyte for an electric double layer capacitor,
Quaternary ammonium cations are N, N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, N, N-diethylpyrrolidinium, 1,1,2-trimethylpyrrolidinium, 1,1 , 3-trimethylpyrrolidinium, 1-ethyl-1,2-dimethylpyrrolidinium, 1-ethyl-1,3-dimethylpyrrolidinium, 2-ethyl-1,1-dimethylpyrrolidinium, 3-ethyl -1,1-dimethylpyrrolidinium, 1,1-diethyl-2-methylpyrrolidinium, 1,1-diethyl-3-methylpyrrolidinium, 1,2-diethyl-1-methylpyrrolidinium, , 3-diethyl-1-methylpyrrolidinium, 1,1,2-triethylpyrrolidinium, 1,1,3-triethylpyrrolidinium, 1,1,2,2-tetramethylpi Lizinium, 1,1,2,3-tetramethylpyrrolidinium, 1,1,2,4-tetramethylpyrrolidinium, 1,1,2,5-tetramethylpyrrolidinium, 1,1,3 4-tetramethylpyrrolidinium, 1,1,3,3-tetramethylpyrrolidinium, 2-ethyl-1,1,2-trimethylpyrrolidinium, 2-ethyl-1,1,3-trimethylpyrrolidi Ni, 3-ethyl-1,1,2-trimethylpyrrolidinium, 3-ethyl-1,1,3-trimethylpyrrolidinium, 2-ethyl-1,1,4-trimethylpyrrolidinium, 4-ethyl -1,1,2-trimethylpyrrolidinium, 2-ethyl-1,1,5-trimethylpyrrolidinium, 3-ethyl-1,1,4-trimethylpyrrolidinium, 1-ethyl-1,2, 2-trimethyl Pyrrolidinium, 1-ethyl-1,2,3-trimethylpyrrolidinium, 1-ethyl-1,3,3-trimethylpyrrolidinium, 1-ethyl-1,2,4-trimethylpyrrolidinium, 1-ethyl -1,2,5-trimethylpyrrolidinium, 1-ethyl-1,3,4-trimethylpyrrolidinium, 2,2-diethyl-1,1-dimethylpyrrolidinium, 2,3-diethyl-1, 1-dimethylpyrrolidinium, 3,3-diethyl-1,1-dimethylpyrrolidinium, 2,4-diethyl-1,1-dimethylpyrrolidinium, 2,5-diethyl-1,1-dimethylpyrrolidi Nium, 3,4-diethyl-1,1-dimethylpyrrolidinium, 1,2-diethyl-1,2-dimethylpyrrolidinium, 1,2-diethyl-1,3-dimethylpyrrolidinium, 1,3-diethyl-1,2-dimethylpyrrolidinium, 1,3-diethyl-1,3-dimethylpyrrolidinium, 1,2-diethyl-1,4-dimethylpyrrolidinium, 1,4-diethyl -1,2-dimethylpyrrolidinium, 1,2-diethyl-1,5-dimethylpyrrolidinium, 1,3-diethyl-1,4-dimethylpyrrolidinium, 1,1,2,2,3- Pentamethylpyrrolidinium, 1,1,2,2,4-pentamethylpyrrolidinium, 1,1,2,2,5-pentamethylpyrrolidinium, 1,1,2,3,4-pentamethyl Pyrrolidinium, 1,1,2,3,5-pentamethylpyrrolidinium, 1,1,3,3,4-pentamethylpyrrolidinium, 1,1,3,3,5-pentamethylpyrrolidi Ni, 1-ethyl-1,2,2,3-te Lamethylpyrrolidinium, 1-ethyl-1,2,2,4-tetramethylpyrrolidinium, 1-ethyl-1,2,2,5-tetramethylpyrrolidinium, 1-ethyl-1,2, 3,4-tetramethylpyrrolidinium, 1-ethyl-1,2,3,5-tetramethylpyrrolidinium, 1-ethyl-1,2,4,5-tetramethylpyrrolidinium, 1-ethyl- 1,3,3,4-tetramethylpyrrolidinium, 1-ethyl-1,3,3,5-tetramethylpyrrolidinium, 2-ethyl-1,1,2,3-tetramethylpyrrolidinium, 2-ethyl-1,1,2,4-tetramethylpyrrolidinium, 2-ethyl-1,1,2,5-tetramethylpyrrolidinium, 2-ethyl-1,1,3,3-tetramethyl Pyrrolidinium, 2-ethyl-1,1,3 -Tetramethylpyrrolidinium, 2-ethyl-1,1,3,5-tetramethylpyrrolidinium, 2-ethyl-1,1,4,4-tetramethylpyrrolidinium, 2-ethyl-1,1 , 4,5-tetramethylpyrrolidinium, 2-ethyl-1,1,5,5-tetramethylpyrrolidinium, 3-ethyl-1,1,2,2-tetramethylpyrrolidinium, 3-ethyl -1,1,2,3-tetramethylpyrrolidinium, 3-ethyl-1,1,2,4-tetramethylpyrrolidinium, 3-ethyl-1,1,2,5-tetramethylpyrrolidinium 3-ethyl-1,1,3,4-tetramethylpyrrolidinium, 3-ethyl-1,1,4,4-tetramethylpyrrolidinium, 3-ethyl-1,1,4,5-tetra Methylpyrrolidinium, 1,1,2,2,3 3-hexamethylpyrrolidinium, 1,1,2,2,3,4-hexamethylpyrrolidinium, 1,1,2,2,3,5-hexamethylpyrrolidinium, 1,1,2, 2,4,4-hexamethylpyrrolidinium, 1,1,2,2,4,5-hexamethylpyrrolidinium, 1,1,2,2,5,5-hexamethylpyrrolidinium, 1,2,3,3,4-hexamethylpyrrolidinium, 1,1,2,3,3,5-hexamethylpyrrolidinium, 1,1,2,3,4,4-hexamethylpyrrolidinium Ni, 1,1,2,3,5,5-hexamethylpyrrolidinium, or 1,1,2,3,4,5-hexamethylpyrrolidinium,
The non-aqueous electrolyte contains 12.9 to 28.7 ppm of an alkali metal cation. The non-aqueous electrolyte according to claim 1 or 2 , wherein the alkali metal cation is sodium ion and / or potassium ion. The quaternary ammonium cation is tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, N, N, N-triethyl-N-methylammonium, or tetraethylammonium , according to claim 1 or 3 , Non-aqueous electrolyte. The quaternary ammonium cation is N, N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, or N, N-diethylpyrrolidinium, according to claim 2 or 3. Non-aqueous electrolyte. The nonaqueous electrolytic solution according to claim 2, 3 or 5 , wherein the quaternary ammonium cation is N-ethyl-N-methylpyrrolidinium. The nonaqueous electrolytic solution according to claim 1 , wherein the quaternary ammonium cation is N, N, N-triethyl-N-methylammonium. General formula (I) in wherein X ^-, BF ₄ ^- non-aqueous electrolyte according to any one of claims 1-7, characterized in that a.   The non-aqueous solvent is at least one selected from the group consisting of propylene carbonate, ethylene carbonate, butylene carbonate, sulfolane, methyl sulfolane, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. The nonaqueous electrolytic solution according to any one of the above.   An electric double layer capacitor comprising the nonaqueous electrolytic solution according to any one of claims 1 to 9 as an electrolytic solution.