JP2013026519A - Electrolyte for electric double layer capacitor, electric double layer capacitor and module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for an electric double layer capacitor, excellent in voltage resistance, safety and low temperature characteristics.SOLUTION: The electrolyte for an electric double layer capacitor includes a solvent (I) for dissolution of an electrolyte salt and an electrolyte salt (II). The solvent (I) for dissolution of an electrolyte salt includes a fluorine-containing chain ether (A) represented by general formula (1): Rf-O-Rf(1) (in the formula, Rfand Rfare the same or different, and represent a 1-10 C alkyl group or 1-10 C fluoroalkyl group, while at least one of Rfand Rfis a fluoroalkyl group.) and a non-fluorinated carbonate (B). A concentration of the electrolyte salt (II) is 1.1 mol/liter or more.

Description

The present invention relates to an electrolytic solution for an electric double layer capacitor, an electric double layer capacitor, and a module.

It is desirable that a solvent for dissolving an electrolyte salt of an electric double layer capacitor in which at least one of a positive electrode and a negative electrode is a polarizable electrode can be used stably with a withstand voltage of 3 V or more. From this viewpoint, ethylene carbonate and an oxidation potential (withstand voltage) The combined use with propylene carbonate which is a high cyclic carbonate is proposed (for example, refer to Patent Document 1). However, the limit of the withstand voltage is limited to about 2.7V.

In addition, for the purpose of improving withstand voltage, a non-aqueous solvent containing sulfolane or a derivative thereof and a specific chain carbonate (chain carbonate) is used (for example, see Patent Document 2), and stability. In order to improve the above, an electrolytic solution in which a specific electrolyte and a fluorine-containing organic solvent are combined has been proposed (see, for example, Patent Document 3).
Further, in order to obtain an electric double layer capacitor having a high withstand voltage and a long lifetime, propylene and at least one selected from the group consisting of a fluorine-containing chain carbonate and a fluorine-containing chain ether as an electrolyte salt dissolving solvent An electrolytic solution containing carbonate has been proposed (see, for example, Patent Document 4).

The solvent for dissolving the electrolyte salt of the electric double layer capacitor is required to improve the safety by increasing the flash point in terms of safety in addition to the voltage resistance.
Patent Document 5 discloses a method of using a fluorine-containing ether such as HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H as an electrolytic solution as a method of increasing the withstand voltage and improving the safety of a non-aqueous electrolyte battery. Has been proposed.
Patent Document 6 proposes an electrolytic solution in which an electrolyte of spirobipyrrolidinium ammonium salt is blended in a mixed solvent of dimethyl carbonate, ethylene carbonate and dimethyl carbonate, and the ignition point thereof is 70 degrees or more.

However, the electrolyte salt-dissolving solvent for these electric double layer capacitors has not been sufficiently studied for low temperature characteristics.

JP 2000-208372 A Japanese Patent Application Laid-Open No. 08-306591 JP 2001-143750 A International Publication No. 2010/055762 Japanese Patent No. 3,807,459 JP 2010-62231 A

An object of the present invention is to provide an electrolytic solution for an electric double layer capacitor that is excellent in withstand voltage, safety, and low temperature characteristics.

That is, the present invention includes an electrolyte salt dissolving solvent (I) and an electrolyte salt (II),
The electrolyte salt dissolving solvent (I) has the general formula (1):
^{Rf 1 -O-Rf 2 (1} )
(In the formula, Rf ¹ and Rf ² are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms, provided that at least one is a fluoroalkyl group.)
And a non-fluorinated carbonate (B), and the concentration of the electrolyte salt (II) is 1.1 mol / liter or more. It is an electrolyte solution for multilayer capacitors.
The mixing ratio (A) / (B) of the fluorine-containing chain ether (A) and the non-fluorinated carbonate (B) is preferably 5/95 to 30/70 by volume ratio.
The electrolyte salt (II) is preferably at least one selected from the group consisting of a tetraalkyl quaternary ammonium salt, a spiro-ring bipyrrolidinium salt, and an imidazolium salt.

The present invention is also an electric double layer capacitor comprising a positive electrode, a negative electrode, and the above-described electrolytic solution for an electric double layer capacitor.
The present invention is also a module comprising the above-described electric double layer capacitor.
The present invention is also a solar power generator characterized in that the above-described module is used as a power source for driving a condensing mirror.
The present invention is also a wind power generator characterized by using the module described above for output smoothing.
The present invention is also a wind power generator characterized by using the above-mentioned module as a power source for pitch control.
The present invention is described in detail below.

In addition to withstand voltage and safety, the present inventors have achieved low temperature characteristics by using an electrolytic solution for an electric double layer capacitor containing a solvent for dissolving an electrolyte salt comprising a specific component and an electrolyte salt having a specific concentration. The present invention was completed.

The electrolytic solution for an electric double layer capacitor of the present invention includes a solvent for dissolving an electrolyte salt composed of a specific component and an electrolyte salt having a specific concentration, and thus has excellent voltage resistance, safety and low temperature characteristics. .

The present invention comprises an electrolyte salt dissolving solvent (I) and an electrolyte salt (II),
The electrolyte salt dissolving solvent (I) has the general formula (1):
^{Rf 1 -O-Rf 2 (1} )
(In the formula, Rf ¹ and Rf ² are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms, provided that at least one is a fluoroalkyl group.)
A fluorine-containing chain ether (A) represented by the following and a non-fluorinated carbonate (B):
An electrolytic solution for an electric double layer capacitor, wherein the concentration of the electrolyte salt (II) is 1.1 mol / liter or more.

The electrolytic solution for electric double layer capacitors of the present invention (hereinafter also referred to as “electrolytic solution of the present invention”) contains an electrolyte salt dissolving solvent (I).
The electrolyte salt dissolving solvent (I) has the general formula (1):
^{Rf 1 -O-Rf 2 (1} )
(Wherein Rf ¹ and Rf ² are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms, provided that at least one is a fluoroalkyl group). The fluorine-containing chain ether (A) represented and the non-fluorinated carbonate (B) are included.
By using such a fluorine-containing chain ether (A) and a non-fluorinated carbonate (B) as a solvent for dissolving the electrolyte salt, the low temperature characteristics of the electrolyte can be improved, and the initial internal resistance can be improved. Can be lowered.

In the fluorine-containing chain ether (A) represented by the general formula (1), Rf ¹ is a fluoroalkyl group having 3 to 6 carbon atoms in that the voltage resistance and initial internal resistance of the electrolytic solution are good. It is preferable that it is C3-C4 fluoroalkyl group. Rf ² is preferably a C2-C4 fluoroalkyl group.

Specific examples of the fluorine-containing chain ether (A) represented by the general formula (1) include, for example, HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H, CF ₃ CF ₂ CH ₂ OCF ₂ CF ₂ H, HCF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ , CF ₃ CF ₂ CH ₂ OCF ₂ CFHCF ₃ , C ₆ F ₁₃ OCH ₃ , C ₆ F ₁₃ OC ₂ H ₅ , C ₈ F ₁₇ OCH ₃ , C ₈ F ₁₇ OC ₂ H ₅ , CF ₃ CFHCF ₂ CH (CH ₃ ) OCF ₂ CFHCF ₃ , HCF ₂ CF ₂ OCH (C ₂ H ₅ ) ₂ , HCF ₂ CF ₂ OC ₄ H ₉ , HCF ₂ CF ₂ OCH ₂ CH (C _{2 H 5) 2, HCF 2 CF} 2 OCH 2 CH (CH 3) 2 and the like. Among them, it is at least one compound selected from the group consisting of HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H and HCF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ because of its excellent voltage resistance. Is preferred.
The fluorine-containing chain ether (A) represented by the general formula (1) may be used alone or in combination of two or more.

The fluorine content of the fluorine-containing chain ether (A) is preferably 50% by weight or more. When it is 50% by weight or more, the oxidation resistance and safety of the electrolytic solution are improved. The fluorine content is more preferably 55 to 70% by weight. The fluorine content is calculated from the structural formula.

The non-fluorinated carbonate (B) is a linear or cyclic carbonate not containing fluorine.
Examples of the non-fluorinated chain carbonate include CH ₃ CH ₂ OCOOCH ₂ CH ₃ (diethyl carbonate; DEC), CH ₃ CH ₂ OCOOCH ₃ (methyl ethyl carbonate; MEC), and CH ₃ OCOOCH ₃ (dimethyl carbonate; DMC). , CH ₃ OCOOCH ₂ CH ₂ CH ₃ (methylpropyl carbonate) and the like.
Of these, dimethyl carbonate (DMC) and methyl ethyl carbonate (MEC) are preferred because they have low viscosity and are excellent in reducing internal resistance and maintaining low temperature characteristics.

Examples of the non-fluorinated cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, vinyl ethylene carbonate, vinylene carbonate and the like.
Of these, propylene carbonate (PC) and ethylene carbonate (EC) are preferable because they have a high dielectric constant and excellent solubility of the electrolyte salt.

In the present invention, the non-fluorinated chain carbonate and the non-fluorinated cyclic carbonate can be used as the non-fluorinated carbonate (B) in that the low temperature characteristics can be improved, the initial internal resistance is low, and the safety can be increased. It is preferable to use together.
Specifically, the non-fluorinated carbonate (B) is preferably propylene carbonate (PC) and dimethyl carbonate (DMC), or propylene carbonate (PC) and ethyl methyl carbonate (EMC).

When a non-fluorinated chain carbonate and a non-fluorinated cyclic carbonate are used in combination, the content ratio (non-fluorinated chain carbonate / non-fluorinated cyclic carbonate) is 1/10 to 3/4 in volume ratio. Is more preferable, and 1/10 to 1/2 is more preferable.

In the electrolytic solution for an electric double layer capacitor of the present invention, the mixing ratio [(A) / (B)] of the fluorine-containing chain ether (A) and the non-fluorinated carbonate (B) is from 5/95 to 5/95. Preferably it is 30/70. If the proportion of the fluorinated chain ether (A) is smaller than the above range, the voltage resistance may be insufficient, and if it exceeds the above range, the initial internal resistance may be too high.
The mixing ratio [(A) / (B)] is a volume ratio, and the lower limit is more preferably 10/90 and the upper limit is more preferably 25/75.

The electrolyte salt dissolving solvent (I) contains the above-mentioned fluorine-containing chain ether (A) and non-fluorinated carbonate (B), but may further contain other solvents.
Examples of other solvents include sulfolane and acetonitrile.
The content of other solvents is preferably 10% by weight or less in the non-aqueous solvent.

The electrolytic solution for an electric double layer capacitor of the present invention contains an electrolyte salt (II).
Examples of the electrolyte salt (II) include conventionally known ammonium salts and metal salts, liquid salts (ionic liquids), inorganic polymer type salts, organic polymer type salts, and the like. Among these, ammonium salts are mentioned because they are suitable for capacitors.

The above ammonium salts are exemplified in (IIa) to (IIe) below.
(IIa) Tetraalkyl quaternary ammonium salt general formula (IIa):

（式中、Ｒ^１ａ、Ｒ^２ａ、Ｒ^３ａ及びＲ^４ａは同じか又は異なり、いずれも炭素数１〜６のエーテル結合を含んでいてもよいアルキル基；Ｘ⁻はアニオン）で示されるテトラアルキル４級アンモニウム塩が好ましく例示できる。また、このアンモニウム塩の水素原子の一部又は全部がフッ素原子及び／又は炭素数１〜４の含フッ素アルキル基で置換されているものも、耐酸化性が向上する点から好ましい。

(Wherein R ^1a , R ^2a , R ^3a and R ^4a are the same or different, and all are alkyl groups optionally containing an ether bond having 1 to 6 carbon atoms; X ⁻ is an anion) Preferred examples include quaternary ammonium salts. In addition, the ammonium salt in which part or all of the hydrogen atoms are substituted with a fluorine atom and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of improving oxidation resistance.

As a specific example, general formula (IIa-1):

（式中、Ｒ^１ａ、Ｒ^２ａ及びＸ⁻は前記と同じ；ｘ及びｙは同じか又は異なり０〜４の整数で、かつｘ＋ｙ＝４）で示されるテトラアルキル４級アンモニウム塩、一般式（ＩＩａ−２）：

(Wherein R ^1a , R ^2a and X ⁻ are the same as above; x and y are the same or different and are integers of 0 to 4 and x + y = 4), a tetraalkyl quaternary ammonium salt represented by the general formula ( IIa-2):

（式中、Ｒ^５ａは炭素数１〜６のアルキル基；Ｒ^６ａは炭素数１〜６の２価の炭化水素基；Ｒ^７ａは炭素数１〜４のアルキル基；ｚは１又は２；Ｘ⁻はアニオン）で示されるアルキルエーテル基含有トリアルキルアンモニウム塩、
などがあげられる。アルキルエーテル基を導入することにより、粘性の低下が図ることができる。

(Wherein R ^5a is an alkyl group having 1 to 6 carbon atoms; R ^6a is a divalent hydrocarbon group having 1 to 6 carbon atoms; R ^7a is an alkyl group having 1 to 4 carbon atoms; z is 1 or 2; X ^- is an alkyl ether group containing trialkylammonium salt represented by the anion),
Etc. By introducing an alkyl ether group, the viscosity can be lowered.

The anion X ⁻ may be an inorganic anion or an organic anion. Examples of the inorganic anion include AlCl ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , TaF ₆ ⁻ , I ⁻ and SbF ₆ ⁻ . Examples of the organic anion include CF ₃ COO ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ^{− and the} like.

Among these, BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , and SbF ₆ ⁻ are preferable from the viewpoint of good oxidation resistance and ion dissociation.

Specific examples of the tetraalkyl quaternary ammonium salt include Et ₄ NBF ₄ , Et ₄ NClO ₄ , Et ₄ NPF ₆ , Et ₄ NAsF ₆ , Et ₄ NSbF ₆ , Et ₄ NCF ₃ SO ₃ , Et ₄ N _{CF 3 SO 2) 2 N,} Et 4 NC 4 F 9 SO 3, Et 3 MeNBF 4, Et 3 MeNClO 4, Et 3 MeNPF 6, Et 3 MeNAsF 6, Et 3 MeNSbF 6, Et 3 MeNCF 3 SO 3, Et _{3 MeN (CF 3 SO 2)} 2 N, may be used _{Et 3 MeNC 4 F 9 SO 3} , in _{particular, Et 4 NBF 4, Et 4} NPF 6, Et 4 NSbF 6, Et 4 NAsF 6, Et 3 MeNBF 4 N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium salt and the like. I can get lost.

(IIb) Spiro ring bipyrrolidinium salt general formula (IIb-1):

（式中、Ｒ^８ａ及びＲ^９ａは同じか又は異なり、いずれも炭素数１〜４のアルキル基；Ｘ⁻はアニオン；ｎ１は０〜５の整数；ｎ２は０〜５の整数）で示されるスピロ環ビピロリジニウム塩、一般式（ＩＩｂ−２）：

(Wherein R ^8a and R ^9a are the same or different and both are alkyl groups having 1 to 4 carbon atoms; X ⁻ is an anion; n1 is an integer of 0 to 5; n2 is an integer of 0 to 5) Spirocyclic bipyrrolidinium salt, general formula (IIb-2):

（式中、Ｒ^１０ａ及びＲ^１１ａは同じか又は異なり、いずれも炭素数１〜４のアルキル基；Ｘ⁻はアニオン；ｎ３は０〜５の整数；ｎ４は０〜５の整数）で示されるスピロ環ビピロリジニウム塩、又は、一般式（ＩＩｂ−３）：

(Wherein, R ^10a and R ^11a are the same or different, and both are alkyl groups having 1 to 4 carbon atoms; X ⁻ is an anion; n3 is an integer of 0 to 5; n4 is an integer of 0 to 5) Spiro ring bipyrrolidinium salt or general formula (IIb-3):

（式中、Ｒ^１２ａおよびＲ^１３ａは同じかまたは異なり、いずれも炭素数１〜４のアルキル基；Ｘ⁻はアニオン；ｎ５は０〜５の整数；ｎ６は０〜５の整数）で示されるスピロ環ビピロリジニウム塩が好ましく挙げられる。また、このスピロ環ビピロリジニウム塩の水素原子の一部または全部がフッ素原子および／または炭素数１〜４の含フッ素アルキル基で置換されているものも、耐酸化性が向上する点から好ましい。

(Wherein R ^12a and R ^13a are the same or different and both are alkyl groups having 1 to 4 carbon atoms; X ⁻ is an anion; n5 is an integer of 0 to 5; n6 is an integer of 0 to 5) Spiro ring bipyrrolidinium salts are preferred. In addition, the spiro-ring bipyrrolidinium salt in which part or all of the hydrogen atoms are substituted with a fluorine atom and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of improving oxidation resistance.

Preferred examples of the anion X ⁻ are the same as in the case of (IIa). Among them, BF ₄ −, PF ₆ −, (CF ₃ SO ₂ ) ₂ N- or (C ₂ F ₅ SO ₂ ) ₂ N− is preferable because of its high dissociation property and low internal resistance under high voltage. preferable.

などが挙げられる。 Preferable specific examples of the spiro ring bipyrrolidinium salt include, for example,

Etc.

This spiro ring bipyrrolidinium salt is excellent in terms of solubility in a solvent, oxidation resistance, and ionic conductivity.

(IIc) Imidazolium salt general formula (IIc):

（式中、Ｒ^１４ａ及びＲ^１５ａは同じか又は異なり、いずれも炭素数１〜６のアルキル基；Ｘ⁻はアニオン）
で示されるイミダゾリウム塩が好ましく例示できる。また、このイミダゾリウム塩の水素原子の一部又は全部がフッ素原子及び／又は炭素数１〜４の含フッ素アルキル基で置換されているものも、耐酸化性が向上する点から好ましい。

(In the formula, R ^14a and R ^15a are the same or different and both are alkyl groups having 1 to 6 carbon atoms; X ⁻ is an anion)
The imidazolium salt shown by can be illustrated preferably. Moreover, it is preferable from the point which oxidation resistance improves what part or all of the hydrogen atom of this imidazolium salt substituted by the fluorine atom and / or the C1-C4 fluorine-containing alkyl group.

Preferred specific examples of the anion X ⁻ are the same as those in (IIa).

As a preferable specific example, for example,

などがあげられる。

Etc.

This imidazolium salt is excellent in terms of low viscosity and good solubility.

(IId): N-alkylpyridinium salt general formula (IId):

（式中、Ｒ^１６ａは炭素数１〜６のアルキル基；Ｘ⁻はアニオン）
で示されるＮ−アルキルピリジニウム塩が好ましく例示できる。また、このＮ−アルキルピリジニウム塩の水素原子の一部又は全部がフッ素原子及び／又は炭素数１〜４の含フッ素アルキル基で置換されているものも、耐酸化性が向上する点から好ましい。

(Wherein R ^16a is an alkyl group having 1 to 6 carbon atoms; X ⁻ is an anion)
An N-alkylpyridinium salt represented by the formula is preferably exemplified. Moreover, what substituted a part or all of the hydrogen atom of this N-alkyl pyridinium salt by the fluorine atom and / or the C1-C4 fluorine-containing alkyl group is preferable from the point which oxidation resistance improves.

Preferred specific examples of the anion X ⁻ are the same as those in (IIa).

As a preferable specific example, for example,

などがあげられる。

Etc.

This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

(IIe) N, N-dialkylpyrrolidinium salt general formula (IIe):

（式中、Ｒ^１７ａ及びＲ^１８ａは同じか又は異なり、いずれも炭素数１〜６のアルキル基；Ｘ⁻はアニオン）
で示されるＮ，Ｎ−ジアルキルピロリジニウム塩が好ましく例示できる。また、このＮ，Ｎ−ジアルキルピロリジニウム塩の水素原子の一部又は全部がフッ素原子及び／又は炭素数１〜４の含フッ素アルキル基で置換されているものも、耐酸化性が向上する点から好ましい。

(Wherein, R ^17a and R ^18a are the same or different and both are alkyl groups having 1 to 6 carbon atoms; X ⁻ is an anion)
N, N-dialkylpyrrolidinium salts represented by Also, oxidation resistance of the N, N-dialkylpyrrolidinium salt in which part or all of the hydrogen atoms are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms is improved. It is preferable from the point.

Preferred specific examples of the anion X ⁻ are the same as those in (IIa).

As a preferable specific example, for example,

などが挙げられる。

Etc.

This N, N-dialkylpyrrolidinium salt is excellent in terms of low viscosity and good solubility.

Of these ammonium salts, (IIa), (IIb) and (IIc) are preferable in terms of good solubility, oxidation resistance and ionic conductivity,

（式中、Ｍｅはメチル基；Ｅｔはエチル基；Ｘ⁻、ｘ、ｙは式（ＩＩａ−１）と同じ）
が好ましい。

(Wherein Me is a methyl group; Et is an ethyl group; X ⁻ , x, and y are the same as those in formula (IIa-1))
Is preferred.

Moreover, you may use lithium salt as electrolyte salt. Examples of the lithium salt _{LiPF 6, LiBF 4, LiAsF 6} , LiSbF 6, LiN (SO 2 C 2 H 5) 2 is preferred.

Further, a magnesium salt may be used to improve the capacity. As the magnesium salt, for example, Mg (ClO ₄ ) ₂ , Mg (OOC ₂ H ₅ ) _{2 and the} like are preferable.

Among these, the electrolyte salt (II) is preferably at least one selected from the group consisting of a tetraalkyl quaternary ammonium salt, a spiro-ring bipyrrolidinium salt, and an imidazolium salt from the viewpoint of maintaining low temperature characteristics. Triethylmethylammonium tetrafluoroborate (TEMABF ₄ ) and spirobipyrrolidinium tetrafluoroborate (SBPBF ₄ ) are more preferable.

The concentration of the electrolyte salt (II) is 1.1 mol / liter or more. If it is less than 1.1 mol / liter, not only the low-temperature characteristics are deteriorated, but also the initial internal resistance is increased. The concentration of the electrolyte salt is preferably 1.25 mol / liter or more.
The upper limit of the concentration is preferably 1.7 mol / liter or less, and more preferably 1.5 mol / liter or less, from the viewpoint of low temperature characteristics.
When the electrolyte salt (II) is triethylmethylammonium tetrafluoroborate (TEMAF ₄ ), the concentration is preferably 1.1 to 1.4 mol / liter in terms of excellent low temperature characteristics.
In the case of spirobipyrrolidinium tetrafluoroborate (SBPBF ₄ ), it is preferably 1.3 to 1.7 mol / liter.

The electrolytic solution for electric double layer capacitors of the present invention may further contain a nitrile compound.
By containing the nitrile compound, the expansion of the electric double layer capacitor can be better suppressed.
As the nitrile compound, the following general formula (2):
R ^1- (CN) _n (2)
(In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms or an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or 2)
The nitrile compound shown by can be mentioned.

In the general formula (2), when n is 1, R ¹ is an alkyl group having 1 to 10 carbon atoms, and when n is 2, R ¹ is an alkylene group having 1 to 10 carbon atoms.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, and decyl. Examples thereof include an alkyl group having 1 to 10 carbon atoms such as a group, and among these, a methyl group and an ethyl group are preferable.

Examples of the alkylene group include alkylene groups having 1 to 10 carbon atoms such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group, a nonylene group, and a decylene group. Among these, a propylene group and an ethylene group are preferable.

Specific examples of the nitrile compound include acetonitrile (CH ₃ —CN), propionitrile (CH ₃ —CH ₂ —CN), glutaronitrile (NC— (CH ₂ ) ₃ —CN), and the like. Among these, acetonitrile and propionitrile are preferable from the viewpoint of reducing resistance.
It is preferable that content of the said nitrile compound is 0-40 volume% in the electrolyte solution for electric double layer capacitors of this invention.

Other additives may be blended in the electrolytic solution for electric double layer capacitors of the present invention as required. Examples of other additives include metal oxides and glass, and these can be added within a range that does not impair the effects of the present invention.

The electrolytic solution for an electric double layer capacitor of the present invention comprises (i) a fluorine-containing unsaturated compound, or (ii) general formula (3):
Rf ³ OH (3)
(In the formula, Rf ³ is an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms)
It is preferable that content of the compound shown by is 5000 ppm or less in total with respect to fluorine-containing chain | strand-shaped ether (A), and it is more preferable that it is 2000 ppm or less.
Compounds (i) and (ii) are impurities contained in the fluorine-containing chain ether. When the amount of impurities is large, the electric double layer capacitor may be expanded and easily deteriorated.
In order to reduce the content of the impurities, the fluorine-containing chain ether used in the present invention is preferably purified in advance.
Examples of the purification method of the fluorine-containing chain ether include a method of rectification using a distillation column having 5 or more theoretical plates. Specifically, for example, a method of subjecting a fluorine-containing chain ether containing impurities to countercurrent extraction using water as an extraction solvent (separating agent) for the fluorine-containing alkyl alcohol can be mentioned.

The counter-current extraction method is a kind of liquid-liquid extraction method, and a vertical type extraction device is used for extraction, and a fluorine-containing chain ether having a large specific gravity (for example, a specific gravity of about 1.5) is used as a crude liquid at the top of the extraction device. Inject water from the bottom, inject water (specific gravity 1.0) from the bottom, and if necessary, make it rise as a water droplet in the usual way, and make the fluorine-containing chain ether crude liquid and water sufficiently contact with each other. In this method, the fluorine-containing alkyl alcohol is extracted into individual water droplets. The water used for extraction is extracted from above the apparatus.
Examples of the countercurrent extraction device include a mixer-settler type extraction device provided with a stirrer in multiple stages.

The electrolytic solution for an electric double layer capacitor of the present invention can be prepared by dissolving an electrolyte salt in a non-aqueous solvent.

The electrolytic solution for electric double layer capacitors of the present invention may be combined with a polymer material that dissolves or swells in the electrolyte salt dissolving solvent (I) to form a gel-like (plasticized) gel electrolyte.

Examples of such a polymer material include conventionally known polyethylene oxide and polypropylene oxide, modified products thereof (JP-A-8-222270, JP-A-2002-1000040); polyacrylate polymers, polyacrylonitrile, and polyvinylidene fluoride. , Fluororesins such as vinylidene fluoride-hexafluoropropylene copolymer (Japanese Patent Publication No. 4-506726, Japanese Patent Publication No. 8-507407, Japanese Patent Laid-Open No. 10-294131); Examples thereof include composites with resins (Japanese Patent Laid-Open Nos. 11-35765 and 11-86630). In particular, it is desirable to use polyvinylidene fluoride or a vinylidene fluoride-hexafluoropropylene copolymer as the polymer material for the gel electrolyte.

In addition, ion conductive compounds described in JP-A-2006-114401 can also be used.

This ion conductive compound has the formula (4):
P- (D) -Q (4)
[Wherein D represents the formula (4-1):
-(D1) _n- (FAE) _m- (AE) _p- (Y) _q- (4-1)
(Where D1 is the formula (4a):

（式中、Ｒｆは架橋性官能基を有していてもよい含フッ素エーテル基；Ｒ^１ｂはＲｆと主鎖を結合する基又は結合手）
で示される側鎖に含フッ素エーテル基を有するエーテル単位；
ＦＡＥは、式（４ｂ）：

(In the formula, Rf is a fluorine-containing ether group optionally having a crosslinkable functional group; R ^1b is a group or a bond that bonds Rf to the main chain)
An ether unit having a fluorine-containing ether group in the side chain represented by
FAE has the formula (4b):

（式中、Ｒｆａは水素原子、架橋性官能基を有していてもよい含フッ素アルキル基；Ｒ^２ｂはＲｆａと主鎖を結合する基又は結合手）
で示される側鎖に含フッ素アルキル基を有するエーテル単位；
ＡＥは、式（４ｃ）：

(Wherein Rfa is a hydrogen atom, a fluorine-containing alkyl group optionally having a crosslinkable functional group; R ^2b is a group or a bond that bonds Rfa to the main chain)
An ether unit having a fluorine-containing alkyl group in the side chain represented by
AE is the formula (4c):

（式中、Ｒ^３ｂは水素原子、架橋性官能基を有していてもよいアルキル基、架橋性官能基を有していてもよい脂肪族環式炭化水素基又は架橋性官能基を有していてもよい芳香族炭化水素基；Ｒ^４ｂはＲ^３ｂと主鎖を結合する基又は結合手）
で示されるエーテル単位；
Ｙは、式（４ｄ−１）〜（４ｄ−３）：

(In the formula, R ^3b has a hydrogen atom, an alkyl group that may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group that may have a crosslinkable functional group, or a crosslinkable functional group. An aromatic hydrocarbon group which may be present; R ^4b is a group or a bond which bonds R ^3b to the main chain)
An ether unit represented by:
Y represents formulas (4d-1) to (4d-3):

の少なくとも１種を含む単位；
ｎは０〜２００の整数；ｍは０〜２００の整数；ｐは０〜１００００の整数；ｑは１〜１００の整数；ただしｎ＋ｍは０ではなく、Ｄ１、ＦＡＥ、ＡＥ及びＹの結合順序は特定されない）；
Ｐ及びＱは同じか又は異なり、水素原子、フッ素原子及び／又は架橋性官能基を含んでいてもよいアルキル基、フッ素原子及び／又は架橋性官能基を含んでいてもよいフェニル基、−ＣＯＯＨ基、−ＯＲ^５ｂ（Ｒ^５ｂは水素原子又はフッ素原子及び／又は架橋性官能基を含んでいてもよいアルキル基）、エステル基又はカーボネート基（ただし、Ｄの末端が酸素原子の場合は−ＣＯＯＨ基、−ＯＲ^５ｂ、エステル基及びカーボネート基ではない）］
で表される側鎖に含フッ素基を有する非晶性含フッ素ポリエーテル化合物である。

A unit comprising at least one of
n is an integer of 0 to 200; m is an integer of 0 to 200; p is an integer of 0 to 10000; q is an integer of 1 to 100; provided that n + m is not 0, and the bonding order of D1, FAE, AE and Y is Not specified);
P and Q are the same or different and are a hydrogen atom, a fluorine atom and / or an alkyl group which may contain a crosslinkable functional group, a phenyl group which may contain a fluorine atom and / or a crosslinkable functional group, -COOH Group, -OR ^5b (R ^5b is a hydrogen atom or a fluorine atom and / or an alkyl group which may contain a crosslinkable functional group), an ester group or a carbonate group (provided that -COOH is used when the terminal of D is an oxygen atom) Group, not —OR ^5b , ester group and carbonate group)]
It is an amorphous fluorine-containing polyether compound which has a fluorine-containing group in the side chain represented by these.

It is preferable that the electrolytic solution for an electric double layer capacitor of the present invention does not freeze at a low temperature (for example, 0 ° C. or −20 ° C.) and does not precipitate an electrolyte salt. Specifically, the viscosity at 0 ° C. is preferably 100 mPa · sec or less, more preferably 30 mPa · sec or less, and particularly preferably 15 mPa · sec or less. Furthermore, specifically, the viscosity at −20 ° C. is preferably 100 mPa · sec or less, more preferably 40 mPa · sec or less, and particularly preferably 15 mPa · sec or less.

The electrolytic solution for electric double layer capacitors of the present invention preferably has a water content of 20 ppm or less. When the water content is within the above range, the long-term reliability, in particular, the expansion suppressing effect is improved. Here, ppm is based on weight, and indicates that water is 0.002 part by weight or less in 100 parts by weight of the non-aqueous electrolyte used in the present invention. The lower the moisture content, the better.

The electrolytic solution for an electric double layer capacitor of the present invention can be suitably applied to an electric double layer capacitor.
The electric double layer capacitor includes a positive electrode, a negative electrode, and an electrolytic solution for an electric double layer capacitor of the present invention. Such an electric double layer capacitor is also one aspect of the present invention.

In the electric double layer capacitor of the present invention, at least one of the positive electrode and the negative electrode is a polarizable electrode, and the following electrodes described in detail in JP-A-9-7896 are used as the polarizable electrode and the nonpolarizable electrode. it can.

The polarizable electrode mainly composed of activated carbon used in the present invention preferably contains a non-activated carbon having a large specific surface area and a conductive agent such as carbon black imparting electron conductivity. The polarizable electrode can be formed by various methods. For example, a polarizable electrode made of activated carbon and carbon black can be formed by mixing activated carbon powder, carbon black, and a phenolic resin, and firing and activating in an inert gas atmosphere and a water vapor atmosphere after press molding. Preferably, the polarizable electrode is joined to the current collector with a conductive adhesive or the like.

Alternatively, activated carbon powder, carbon black, and a binder can be kneaded in the presence of alcohol, formed into a sheet, and dried to form a polarizable electrode. For example, polytetrafluoroethylene is used as the binder. In addition, activated carbon powder, carbon black, binder and solvent are mixed to form a slurry, and this slurry is coated on the metal foil of the current collector and dried to obtain a polarizable electrode integrated with the current collector. it can.

An electric double layer capacitor may be formed by using a polarizable electrode mainly composed of activated carbon for both electrodes, but a configuration using a non-polarizable electrode on one side, for example, a positive electrode mainly composed of a battery active material such as a metal oxide, and activated carbon A structure combining a polarizable electrode negative electrode mainly composed of carbon, a negative electrode mainly composed of a carbon material capable of reversibly occluding and releasing lithium ions, or a negative electrode composed mainly of lithium metal or lithium alloy and activated carbon. A combination with a polar electrode is also possible.

Further, carbonaceous materials such as carbon black, graphite, expanded graphite, porous carbon, carbon nanotube, carbon nanohorn, and ketjen black may be used instead of or in combination with activated carbon.

The non-polarizable electrode is preferably composed mainly of a carbon material capable of reversibly occluding and releasing lithium ions, and an electrode obtained by occluding lithium ions in this carbon material is used for the electrode. In this case, a lithium salt is used as the electrolyte. According to the electric double layer capacitor having this configuration, a higher withstand voltage exceeding 4 V can be obtained.

The solvent used for preparing the slurry in the preparation of the electrode is preferably a solvent that dissolves the binder. According to the type of the binder, N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, phthalate Dimethyl acid, ethanol, methanol, butanol or water is appropriately selected.

Examples of the activated carbon used for the polarizable electrode include phenol resin-based activated carbon, coconut-based activated carbon, and petroleum coke-based activated carbon. Among these, it is preferable to use petroleum coke activated carbon or phenol resin activated carbon in that a large capacity can be obtained. Activated carbon activation treatment methods include a steam activation treatment method, a molten KOH activation treatment method, and the like, and it is preferable to use activated carbon obtained by a molten KOH activation treatment method in terms of obtaining a larger capacity.

Preferred conductive agents used for the polarizable electrode include carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, metal fiber, conductive titanium oxide, and ruthenium oxide. The mixing amount of the conductive agent such as carbon black used for the polarizable electrode is so that good conductivity (low internal resistance) is obtained, and if it is too much, the product capacity is reduced. It is preferable to set it as 50 mass%.

Moreover, as the activated carbon used for the polarizable electrode, activated carbon having an average particle size of 20 μm or less and a specific surface area of 1500 to 3000 m ² / g is used so as to obtain a large capacity and low internal resistance electric double layer capacitor. Is preferred. Further, as a preferable carbon material for constituting an electrode mainly composed of a carbon material capable of reversibly inserting and extracting lithium ions, natural graphite, artificial graphite, graphitized mesocarbon spherule, graphitized whisker, gas layer Examples thereof include a grown carbon fiber, a fired product of furfuryl alcohol resin, and a fired product of novolac resin.

The current collector is only required to be chemically and electrochemically corrosion resistant. As the current collector of the polarizable electrode mainly composed of activated carbon, stainless steel, aluminum, titanium or tantalum can be preferably used. Of these, stainless steel or aluminum is a particularly preferable material in terms of both characteristics and cost of the obtained electric double layer capacitor. As the current collector of the electrode mainly composed of a carbon material capable of reversibly inserting and extracting lithium ions, stainless steel, copper or nickel is preferably used.

In addition, in order to preliminarily store lithium ions in a carbon material capable of reversibly inserting and extracting lithium ions, (1) mixing powdered lithium with a carbon material capable of reversibly inserting and extracting lithium ions. (2) A lithium foil is placed on an electrode formed of a carbon material capable of reversibly occluding and releasing lithium ions and a binder, and the electrode is in contact with the lithium salt. A method in which lithium is ionized by immersing it in an electrolyte solution in which lithium is ionized and lithium ions are taken into the carbon material; (3) formed by a carbon material and a binder capable of reversibly inserting and extracting lithium ions; Place the electrode on the negative side, place lithium metal on the positive side, immerse it in a non-aqueous electrolyte containing lithium salt as an electrolyte, and pass an electric current to make an electrochemical carbon material A method of incorporating in a state in which lithium has been ionized.

As the electric double layer capacitor, a wound type electric double layer capacitor, a laminate type electric double layer capacitor, a coin type electric double layer capacitor, etc. are generally known, and the electric double layer capacitor of the present invention is also in these types. Can do.

For example, in a wound electric double layer capacitor, a positive electrode and a negative electrode made of a laminate (electrode) of a current collector and an electrode layer are wound through a separator to produce a wound element, and the wound element is made of aluminum. And then filled with an electrolytic solution, preferably a non-aqueous electrolytic solution, and then sealed and sealed with a rubber sealing body.

As the separator, conventionally known materials and structures can be used in the present invention. For example, a polyethylene porous membrane, polypropylene fiber, glass fiber, cellulose fiber non-woven fabric and the like can be mentioned.

In addition, by a known method, a laminate type electric double layer capacitor in which a sheet-like positive electrode and a negative electrode are laminated via an electrolytic solution and a separator, and a positive electrode and a negative electrode are formed into a coin shape by fixing with a gasket and the electrolytic solution and the separator. A configured coin type electric double layer capacitor can also be used.

In addition to the electric double layer capacitor, the electrolytic solution in the present invention is also useful as an electrolytic solution for electrochemical devices including various electrolytic solutions. Electrochemical devices include lithium secondary batteries, radical batteries, solar cells (especially dye-sensitized solar cells), fuel cells, various electrochemical sensors, electrochromic elements, electrochemical switching elements, aluminum electrolytic capacitors, tantalum electrolytic capacitors A lithium secondary battery is particularly suitable. In addition, it can be used as an ionic conductor of an antistatic coating material.

A module comprising the electric double layer capacitor of the present invention is also one aspect of the present invention.
Examples of using the module of the present invention include the following.
HEV car or PEV car used for power regeneration and power source of various in-vehicle equipments; motorcycles such as motorcycles or scooters used for starters; construction equipment used for power sources; power regeneration Used trains such as Shinkansens; Solar power generators used for driving power for condensing mirrors; Wind generators used for output smoothing or power sources for pitch control; Used for output smoothing Photovoltaic generator used for power storage; Instantaneous charging system, non-contact charging system, sag / power failure guarantee device used for power storage, or UPS; Tools, robots, or copiers; communication equipment or elevators used as power regeneration; toys or road signs used as power supplies;

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to such examples.

The following measurement methods were used in the examples and comparative examples.

(1) Composition analysis NMR method: AC-300 manufactured by BRUKER is used.
¹⁹ F-NMR:
Measurement conditions: 282 MHz (trichlorofluoromethane = 0 ppm)
¹ H-NMR:
Measurement conditions: 300 MHz (tetramethylsilane = 0 ppm)

(2) Concentration (GC%) analysis gel chromatography (GC) method: GC-17A manufactured by Shimadzu Corporation is used.
Column: DB624 (Length 60, ID 0.32, Film 1.8 μm)
Measurement limit: 0.001%

Synthesis Example 1 Synthesis of HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H The inside of a 6 L autoclave made of stainless steel was evacuated, 401 g of potassium hydroxide (7.15 mol), 1604 mL of water, and fluorine-containing alkyl alcohol. After injecting 1716 g (13 mol) of 2,2,3,3-tetrafluoro-1-propanol: HCF ₂ CF ₂ CH ₂ OH (boiling point 109 ° C., specific gravity 1.4), vacuum-nitrogen replacement 20 times at room temperature went. After evacuating the system, tetrafluoroethylene (TFE) was filled to 0.1 MPa, and the reaction system was heated to 85 ° C. After the internal temperature reached 85 ° C., TFE was added little by little so that the reaction pressure was maintained at 0.5 to 0.8 MPa. The system internal temperature was adjusted to maintain 75 to 95 ° C.

When the amount of TFE added was 0.5 mol as a ratio to 1 mol of fluorine-containing alkyl alcohol, the supply was stopped and the reaction was continued with stirring. When no pressure drop in the autoclave was observed, the internal temperature of the autoclave was returned to room temperature, unreacted TFE was released, and the reaction was terminated. The time required 5 hours.

The lower layer fluorine-containing ether of the product liquid is HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H (boiling point 92 ° C., specific gravity 1.52), and the composition of the lower layer fluorine-containing ether product liquid analyzed by GC is fluorine-containing. Ether concentration 98.7%, HCF ₂ CF ₂ CH ₂ OH 1.02%, CF ₂ = CFCH ₂ OCF ₂ CF ₂ H 0.05%, HCF ₂ CF = CHOCF ₂ CF ₂ H 0.23 %Met.

Preparation Example 1 Preparation of Aqueous Dispersion of PTFE Particles An emulsifier CF ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ was adjusted to a concentration of 0.15% by mass in a 6 L internal volume SUS polymerization tank equipped with a stirrer. 3500 g of pure water and 100 g of granular paraffin wax were added and sealed. The inside of the tank was evacuated after vacuum nitrogen substitution. Thereafter, tetrafluoroethylene (TFE) was charged to 0.7 MPaG in the tank while stirring at 85 ° C. and 265 rpm. Next, 20 g of an aqueous solution in which 525 mg of disuccinic acid peroxide (DSP) was dissolved was pressed into the tank with nitrogen. In order not to leave any liquid in the middle of the reaction tube, 20 g of water was again injected with nitrogen to wash the piping. Thereafter, the TFE pressure was set to 0.8 MPa, stirring was maintained at 265 rpm, and the internal temperature was maintained at 85 ° C. One hour after the introduction of the DSP, 19 mg of ammonium persulfate (APS) was dissolved in 20 g of pure water, and this was press-fitted with nitrogen. In order not to leave any liquid in the middle of the reaction tube, 20 g of water was again injected with nitrogen to wash the piping. TFE was added and charged so that the pressure in the tank was maintained at 0.8 MPa. When the added monomer reached 1195 g, stirring was stopped and the gas in the tank was blown to complete the reaction. The inside of the tank was cooled, and the contents were collected in a plastic container to obtain an aqueous dispersion of PTFE particles. The solid content concentration of the aqueous dispersion by the dry weight method was 31.4% by mass. The average primary particle diameter of the aqueous dispersion was 0.29 μm.

In order to measure the standard specific gravity and the melting point, 500 ml of the obtained aqueous dispersion of PTFE particles was diluted with deionized water so that the solid concentration was about 15% by mass, 1 ml of nitric acid was added, and the mixture was vigorously stirred until solidified. The obtained aggregate was dried at 145 ° C. for 18 hours to obtain PTFE powder. It was 2.189 when standard specific gravity [SSG] was measured using the obtained PTFE powder. The melting point analyzed by DSC was 325.9 ° C.

Preparation Example 2 Preparation of Aqueous Dispersion of TFE-HFP-VdF Copolymer F (CF ₂ ) ₅ COONH ₄ is 3300 ppm and CH ₂ = CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ was sealed with 200 ppm pure water. The inside of the tank was purged with nitrogen and then evacuated, and ethane as a chain transfer agent was charged with a syringe in an amount equivalent to 400 cc by vacuum suction. Thereafter, while stirring at 70 ° C. and 450 rpm, a mixed gas monomer having a VdF / TFE / HFP composition ratio of 50/38/12 mol% was charged to 0.39 MPaG in the tank. Then, the reaction was started by injecting an aqueous solution obtained by dissolving 137.2 mg of APS in 10 g of water with nitrogen. 10 g of water was again injected with nitrogen so that no liquid remained in the middle of the reaction tube.

A mixed monomer having a VdF / TFE / HFP composition ratio of 60/38/2 mol% was additionally charged so as to maintain the pressure in the tank. When the amount of additional monomer reached 346 g, stirring was slowed down and the gas in the tank was blown to complete the reaction. The inside of the tank was cooled, and 1708 g of an aqueous dispersion of VdF / TFE / HFP copolymer (hereinafter referred to as “THV”) particles was collected in a container. The solid content concentration of the aqueous dispersion by the dry weight method was 20.4% by mass. When the copolymer composition was examined by NMR analysis, it was VdF / TFE / HFP = 59.0 / 38.9 / 2.1 (mol%), and the melting point analyzed by DSC was 145.9 ° C.

Preparation Example 3 Preparation of PTFE / THV Organosol 40.0 g of the aqueous dispersion of PTFE particles obtained in Preparation Example 1, 61.5 g of the aqueous dispersion of THV particles obtained in Preparation Example 2, and 200 mL of hexane 16 g It took in the beaker and stirred with the mechanical stirrer. While stirring, 60 g of acetone was added, and then stirred for 3 minutes. After completion of the stirring, the resulting coagulated product and the supernatant liquid mainly composed of water were separated by filtration. About 150 g of NMP was added to the remaining hydrous coagulum and stirred for 5 minutes. This was transferred to a 500 ml eggplant flask, the water was removed with an evaporator, and 120 g of organosol in which PTFE particles were uniformly dispersed in NMP was obtained. When the solid content concentration of the organosol was measured, it was 18.5% by mass, and the water concentration measured by the Karl Fischer method was 100 ppm or less. The mass ratio of PTFE / THV as measured by solid state NMR was 53/47. Further, when this organosol was allowed to stand and visually observed, no separated layers or particles were observed even after 10 days or more.

Example 1
(Production of electrodes)
100 parts by weight of activated carbon particles (manufactured by Kuraray Chemical Co., Ltd., YP50F), 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., Denka Black FX-35), Ketjen Black (Ketjen Black) 12 parts by weight of International Co., Ltd., carbon ECP600JD), 7 parts by weight of PVdF binder (Kureha Co., Ltd., KF-7200), and 3 parts by weight of the organosol of Preparation Example 3 corresponding to the solid content were mixed. Was prepared.

Edged aluminum (20CB manufactured by Nihon Densetsu Kogyo Co., Ltd., thickness of about 20 μm) is prepared as a current collector, and a conductive paint (manufactured by Nippon Graphite Industry Co., Ltd.) is used on both sides of the current collector using a coating device. A bunny height T602) was applied to form a conductive layer (thickness: 7 ± 1 μm).

Next, the electrode slurry prepared above was applied to the conductive layer formed on both sides of the current collector using a coating apparatus to form an electrode layer (positive electrode thickness: 100 μm, negative electrode thickness: 80 μm) on both sides, An electrode was produced.

Hereinafter, the current collector, the conductive layer, and the activated carbon layer are collectively referred to as an electrode.

(Preparation of electrolyte 1)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When triethylmethylammonium tetrafluoroborate (TEMA) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.1 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

(Production of laminated cell electric double layer capacitor)
The electrode is cut into a predetermined size (20 × 72 mm), and an electrode lead is bonded to the aluminum surface of the current collector by welding to form a laminate container (part number: D-EL40H, manufacturer: Dai Nippon Printing Co., Ltd.) ), Injecting and impregnating the electrolyte 1 in a dry chamber with a separator made by cutting TF45-30 of Nippon Kogyo Paper Industries Co., Ltd. into a predetermined size (30 × 82 mm), The laminate cell was produced by sealing.

Example 2
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 2 was used.

(Preparation of electrolyte 2)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When triethylmethylammonium tetrafluoroborate (TEMA) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.25 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 3
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 3 was used.

(Preparation of electrolyte 3)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When triethylmethylammonium tetrafluoroborate (TEMA) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt to a concentration of 1.4 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 4
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 4 was used.

(Preparation of electrolyte 4)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When triethylmethylammonium tetrafluoroborate (TEMA) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.5 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 5
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 5 was used.

(Preparation of electrolyte 5)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.3 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 6
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 6 was used.

(Preparation of electrolyte 6)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.5 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 7
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 7 was used.

(Preparation of electrolyte solution 7)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.7 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 8
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 8 was used.

(Preparation of electrolyte 8)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. This dissolving an electrolyte salt for a nonaqueous solvent, it was added tetrafluoroboric acid spirobipyrrolidinium (SBP) BF ₄ so as to have a 2.0 mol / liter concentration, was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 9
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 9 was used.

(Preparation of electrolyte 9)
Propylene carbonate (PC), methyl ethyl carbonate (MEC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 70/10/20 to dissolve electrolyte salt non-water A solvent was prepared. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.1 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 10
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 10 was used.

(Preparation of electrolyte 10)
Propylene carbonate (PC), methyl ethyl carbonate (MEC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 70/10/20 to dissolve electrolyte salt non-water A solvent was prepared. This dissolving an electrolyte salt for a nonaqueous solvent, it was added tetrafluoroboric acid spirobipyrrolidinium (SBP) BF ₄ so as to have a 1.25 mol / liter concentration, was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 11
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 11 was used.

(Preparation of electrolyte solution 11)
Propylene carbonate (PC), methyl ethyl carbonate (MEC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 70/10/20 to dissolve electrolyte salt non-water A solvent was prepared. This dissolving an electrolyte salt for a nonaqueous solvent, it was added tetrafluoroboric acid spirobipyrrolidinium (SBP) BF ₄ so as to have a 1.4 mol / liter concentration, was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 12
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 12 was used.

(Preparation of electrolyte solution 12)
Propylene carbonate (PC), dimethyl carbonate (DMC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 are mixed at a volume ratio of 70/10/20 to dissolve the electrolyte salt in a nonaqueous solvent. Was prepared. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.3 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 13
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 13 was used.

(Preparation of electrolytic solution 13)
Propylene carbonate (PC), dimethyl carbonate (DMC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 are mixed at a volume ratio of 70/10/20 to dissolve the electrolyte salt in a nonaqueous solvent. Was prepared. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.5 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Example 14
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 14 was used.

(Preparation of electrolytic solution 14)
Propylene carbonate (PC), dimethyl carbonate (DMC), and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 are mixed at a volume ratio of 70/10/20 to dissolve the electrolyte salt in a nonaqueous solvent. Was prepared. When spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.7 mol / liter, it was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Comparative Example 1
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 15 was used.

(Preparation of electrolytic solution 15)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. When triethylmethylammonium tetrafluoroborate (TEMA) BF ₄ was added to this non-aqueous solvent for dissolving electrolyte salt so as to have a concentration of 1.0 mol / liter, it was dissolved uniformly. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The water content of the non-aqueous electrolyte after drying was 20 ppm.

Comparative Example 2
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 16 was used.

(Preparation of electrolytic solution 16)
Propylene carbonate (PC) and HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H of Synthesis Example 1 were mixed at a volume ratio of 80/20 to prepare a nonaqueous solvent for dissolving an electrolyte salt. This dissolving an electrolyte salt for a nonaqueous solvent, it was added tetrafluoroboric acid spirobipyrrolidinium (SBP) BF ₄ so as to have a 1.0 mol / liter concentration, was uniformly dissolved. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

Comparative Example 3
A laminated cell electric double layer capacitor was produced in the same manner as in Example 1 except that the electrolytic solution 17 was used.

(Preparation of electrolytic solution 17)
Propylene carbonate (PC) was used as the non-aqueous solvent for dissolving the electrolyte salt, and spirobipyrrolidinium tetrafluoroborate (SBP) BF ₄ was added to this to a concentration of 1.5 mol / liter. However, it dissolved uniformly. A 5% by weight molecular sieve was added to the obtained non-aqueous electrolyte and left for 10 hours. Thereafter, the molecular sieve was removed by filtration. The moisture content of the non-aqueous electrolyte after drying was 2 ppm.

(Capacitor characteristics evaluation)
The obtained electric double layer capacitor was measured for capacitance retention and internal resistance increase ratio.

(1) Capacitance retention rate, internal resistance increase ratio Laminated capacitor is placed in a thermostatic chamber at a temperature of 25 ° C., 10 ° C., or −10 ° C., and a voltage of 3.0 V is applied for 500 hours. And the internal resistance was measured. The capacitance retention rate (%) and the internal resistance increase ratio were calculated according to the following calculation formula. The results are shown in Tables 1 and 2.

Since the electrolytic solution of the present invention has excellent voltage resistance, safety and low temperature characteristics, it can be suitably applied as an electrolytic solution for electric double layer capacitors.

Claims (8)

Including electrolyte salt dissolving solvent (I) and electrolyte salt (II),
The electrolyte salt dissolving solvent (I) has the general formula (1):
^{Rf 1 -O-Rf 2 (1} )
(In the formula, Rf ¹ and Rf ² are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms, provided that at least one is a fluoroalkyl group.)
A fluorine-containing chain ether (A) represented by the following and a non-fluorinated carbonate (B):
An electrolytic solution for an electric double layer capacitor, wherein the concentration of the electrolyte salt (II) is 1.1 mol / liter or more. The electric double layer capacitor according to claim 1, wherein the mixing ratio (A) / (B) of the fluorine-containing chain ether (A) and the non-fluorinated carbonate (B) is from 5/95 to 30/70 by volume. Electrolyte. The electrolytic solution for an electric double layer capacitor according to claim 1 or 2, wherein the electrolyte salt (II) is at least one selected from the group consisting of a tetraalkyl quaternary ammonium salt, a spiro-ring bipyrrolidinium salt, and an imidazolium salt. . An electric double layer capacitor comprising the positive electrode, the negative electrode, and the electrolytic solution for an electric double layer capacitor according to claim 1, 2 or 3. A module comprising the electric double layer capacitor according to claim 4. 6. A solar power generator, wherein the module according to claim 5 is used as a power source for driving a condensing mirror. A wind power generator characterized by using the module according to claim 5 for output smoothing. A wind power generator using the module according to claim 5 as a power source for pitch control.