JP2007243111A - Electrolytic solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrolytic solution which is excellent in fire retardancy, low temperature characteristics and a withstand voltage, and which is high in the solubility of electroyte salt, and which is excellent in the compatibility with hydrocarbon system solvent. <P>SOLUTION: The electrolytic solution contains fluorine containing lactone shown by a formula (I) and electrolyte salt, (in the formula (I), either A or B is CX<SP>6</SP>X<SP>7</SP>(X<SP>6</SP>and X<SP>7</SP>are the same or different, and H, F, Cl, CF<SB>3</SB>, CH<SB>3</SB>or hydrogen atom is alky group which may be replaced by halogen atom, and which may include hetero atom in chain), and the other is atomic oxygen; Rf<SP>1</SP>is fluorine containing ether group, fluorine containing alkoxy group or fluorine containing alky group whose carbon number is two or more; X<SP>1</SP>and X<SP>2</SP>are the same or different, and H, F, Cl, CF<SB>3</SB>or CH<SB>3</SB>; X<SP>3</SP>to X<SP>5</SP>are the same or different, and H, F, Cl or hydrogen atom is alky group which may be replaced by halogen atom, and which may include hetero atom in chain; n=0 or 1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic solution containing a fluorine-containing lactone having a fluorine-containing ether group or a fluorine-containing alkyl group and an electrolyte salt.

  In addition to carbonates, lactones are used as solvents for electrolyte salts of lithium secondary batteries, solar batteries, radical batteries, and capacitors. However, lactones have a low flash point and high flammability, so there is a risk of ignition and explosion due to overcharging and overheating, and there is a problem that output is reduced due to low viscosity and low conductivity at low temperatures. There is. Moreover, since hydrolyzability is high, there also exists a fault that it is very difficult to use.

  Further, in the lithium secondary battery, an increase in the withstand voltage of the electrolytic solution is required to increase the capacity. Furthermore, in the capacitor, it is desirable that both the negative electrode and the positive electrode are hard carbon, and it is desirable that they can be stably used particularly at 3 V or more, but conventionally used solvents for electrolyte salts such as carbonates and lactones. Then, since the decomposition of the electrolyte occurs at 3 V or more, it cannot be used.

  Furthermore, in the case of electrolytes for capacitors and radical batteries that repeatedly charge and discharge in the same way as lithium secondary batteries, in addition to improved flame retardancy and withstand voltage, the viscosity does not increase even at low temperatures and the decrease in conductivity is small. Improvement of low temperature characteristics is desired.

  Examples of lactones used as a solvent for the electrolyte salt are described in Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4.

  Patent Documents 1 and 2 propose that α-fluorinated-γ-butyrolactone, β-fluorinated-γ-butyrolactone, and γ-fluorinated-γ-butyrolactone are used as an electrolytic solution.

  Patent Document 3 proposes that a γ-butyrolactone derivative in which two γ-position hydrogen atoms of γ-butyrolactone are substituted with 1 to 2 trifluoromethyl groups is used as an electrolytic solution.

  Patent Document 4 proposes that a γ-butyrolactone derivative having an alkoxy group at the γ-position of γ-butyrolactone is used as the electrolytic solution.

  However, the lactones described in Patent Document 1, Patent Document 2, and Patent Document 4 are insufficient in terms of withstand voltage and flame retardancy because of their low fluorine content, and further improvements are required.

  In addition, the lactones described in Patent Document 3 have insufficient solubility of the electrolyte salt and are easily decomposed under basicity, and further improvements in these respects are required.

JP 11-195429 A Japanese Patent Laid-Open No. 7-283083 JP 2001-256983 A JP 2003-163031 A

  The present invention seeks to solve the problems associated with the prior art as described above, and is excellent in low-temperature characteristics and withstand voltage, improved in flame retardancy, high solubility of electrolyte salt, and base. It is an object of the present invention to provide an electrolytic solution that is stable even under the property of the resin and excellent in compatibility with a hydrocarbon solvent.

  As a result of intensive studies on a compound satisfying the required characteristics of the electrolyte solution of the non-aqueous electrolyte based on the fluorine-containing lactone, the present inventors have found that one of the fluorine-containing lactones has a fluorine-containing ether group, a fluorine-containing alkoxy group, or a carbon number. It has been found that the above-mentioned problems can be solved by arranging two or more fluorine-containing alkyl groups, and the present invention has been completed.

  That is, the present invention relates to the formula (I):

（式中、ＡおよびＢはいずれか一方が酸素原子であり、他方が結合している水素原子が置換されているか置換されていない炭素原子；Ｒｆ¹はフッ素含有率が１０〜７６質量％である含フッ素エーテル基、含フッ素アルコキシ基または炭素数２以上の含フッ素アルキル基；Ｘ¹およびＸ²は同じかまたは異なり、いずれもＨ、Ｆ、Ｃｌ、ＣＦ₃またはＣＨ₃；Ｘ³〜Ｘ⁵はＨ、Ｆ、Ｃｌまたは水素原子がハロゲン原子で置換されていてもよくヘテロ原子を鎖中に含んでいてもよいアルキル基；ｎ＝０または１）で示される含フッ素ラクトン（Ｉ）と電解質塩（II）とを含む電解液に関する。

(In the formula, any one of A and B is an oxygen atom, and the hydrogen atom to which the other is bonded is substituted or unsubstituted carbon atom; Rf ¹ has a fluorine content of 10 to 76% by mass) A fluorine-containing ether group, a fluorine-containing alkoxy group or a fluorine-containing alkyl group having 2 or more carbon atoms; X ¹ and X ² are the same or different and all are H, F, Cl, CF ₃ or CH ₃ ; X ^{3 to} X ⁵ represents H, F, Cl, or an alkyl group in which a hydrogen atom may be substituted with a halogen atom and may contain a hetero atom in the chain; and a fluorine-containing lactone (I) represented by n = 0 or 1) The present invention relates to an electrolytic solution containing an electrolyte salt (II).

  According to the present invention, there is provided an electrolytic solution capable of improving the flame retardancy, low temperature characteristics, withstand voltage, electrolyte salt solubility, basic stability and compatibility with hydrocarbon solvents in a well-balanced manner. can do.

  The electrolytic solution of the present invention contains a fluorine-containing lactone (I) having a specific fluorine-containing ether group or fluorine-containing alkyl group on one side and an electrolyte salt (II), which is a solvent for dissolving an electrolyte salt.

（式中、ＡおよびＢはいずれか一方がＣＸ⁶Ｘ⁷（Ｘ⁶およびＸ⁷は同じかまたは異なり、いずれもＨ、Ｆ、Ｃｌ、ＣＦ₃、ＣＨ₃または水素原子がハロゲン原子で置換されていてもよくヘテロ原子を鎖中に含んでいてもよいアルキル基）であり、他方は酸素原子；Ｒｆ¹はフッ素含有率が含フッ素エーテル基、含フッ素アルコキシ基または炭素数２以上の含フッ素アルキル基；Ｘ¹およびＸ²は同じかまたは異なり、いずれもＨ、Ｆ、Ｃｌ、ＣＦ₃またはＣＨ₃；Ｘ³〜Ｘ⁵はＨ、Ｆ、Ｃｌまたは水素原子がハロゲン原子で置換されていてもよくヘテロ原子を鎖中に含んでいてもよいアルキル基；ｎ＝０または１）で示される。 The specific fluorine-containing lactone (I) used in the present invention has the formula (I):

(In the formula, either one of A and B is CX ⁶ X ⁷ (X ⁶ and X ⁷ are the same or different, and any one of H, F, Cl, CF ₃ , CH ₃ or a hydrogen atom is substituted with a halogen atom) And the other is an oxygen atom; Rf ¹ is a fluorine-containing ether group, fluorine-containing alkoxy group or fluorine-containing fluorine atom having 2 or more carbon atoms. An alkyl group; X ¹ and X ² are the same or different and all are H, F, Cl, CF ₃ or CH ₃ ; X ^{3 to} X ⁵ are H, F, Cl or a hydrogen atom substituted by a halogen atom; Or an alkyl group which may contain a hetero atom in the chain; n = 0 or 1).

（式中、Ａ、Ｂ、Ｒｆ¹、Ｘ¹、Ｘ²およびＸ³は式（Ｉ）と同じ）で示される。 The fluorine-containing lactone represented by the formula (I) preferably has a 5-membered ring structure, and the formula (IA):

(Wherein A, B, Rf ¹ , X ¹ , X ² and X ³ are the same as in formula (I)).

（式中、Ｒｆ¹、Ｘ¹、Ｘ²、Ｘ³、Ｘ⁶およびＸ⁷は式（Ｉ）と同じ）で示される含フッ素ラクトン（ＩＡ−１）と、
式（ＩＡ−２）：

（式中、Ｒｆ¹、Ｘ¹、Ｘ²、Ｘ³、Ｘ⁶およびＸ⁷は式（Ｉ）と同じ）で示される含フッ素ラクトン（ＩＡ−２）がある。 The fluorine-containing lactone represented by the formula (IA) has a formula (IA-1):

(Wherein Rf ¹ , X ¹ , X ² , X ³ , X ⁶ and X ⁷ are the same as those in formula (I)),
Formula (IA-2):

(Wherein Rf ¹ , X ¹ , X ² , X ³ , X ⁶ and X ⁷ are the same as those in formula (I)).

  Of these, the fluorine-containing lactone (IA-1) represented by the formula (IA-1) is preferable from the viewpoint of ease of synthesis.

（式中、Ａ、Ｂ、Ｒｆ¹、Ｘ¹、Ｘ²、Ｘ³、Ｘ⁴およびＸ⁵は式（Ｉ）と同じ）で示される含フッ素ラクトンが好ましい。 As the fluorine-containing lactone having a 6-membered ring (n = 1), for example, the formula (IB):

(Wherein A, B, Rf ¹ , X ¹ , X ² , X ³ , X ⁴ and X ⁵ are the same as those in formula (I)).

  Since the fluorinated lactone (I) of the present invention has a fluorinated ether structure or a fluorinated alkyl group having 2 or more carbon atoms, it further reduces the viscosity at low temperature, increases the flash point, and further dissolves the electrolyte salt. Improvement can be expected.

Rf ¹ is a fluorine-containing ether group, preferably a fluorine-containing ether group having 2 to 17 carbon atoms, or a fluorine-containing alkoxy group, preferably a fluorine-containing alkoxy group having 1 to 17 carbon atoms, or the number of carbon atoms Two or more fluorine-containing alkyl groups, preferably a fluorine-containing alkyl group having 2 to 17 carbon atoms.

The fluorine content of Rf ¹ is preferably 10% by mass or more. If the fluorine content is low, the effect of improving the viscosity at low temperatures and the effect of improving the flash point cannot be obtained sufficiently. From this viewpoint, the fluorine content of Rf ¹ is preferably 20% by mass or more, and more preferably 30% by mass or more. The upper limit is usually 76% by mass. Note that the fluorine content of Rf ¹ is calculated from the composition of the constituent atoms.

  Moreover, the fluorine content of the whole fluorine-containing lactone (I) is 10% by mass or more, preferably 20% by mass or more, and the upper limit is usually 76% by mass. The method for measuring the fluorine content of the entire fluorinated lactone is based on the combustion method described later.

As for carbon number of a fluorine-containing ether group, 2-17 are preferable. When the number of carbon atoms exceeds 17, the viscosity of the fluorinated lactone (I) increases and the number of fluorine-containing groups increases, so that the solubility of the electrolyte salt decreases due to a decrease in dielectric constant, and the phase with other solvents. A decrease in solubility may be observed. The number of carbon atoms of Rf ¹ from this point of view is preferably from 2 to 10, 2 to 7 is more preferable.

  The alkylene group constituting the ether portion of the fluorine-containing ether group may be a linear or branched alkylene group as long as the fluorine content is as described above. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below.

(i) Minimum linear structural unit:
_{-CH 2 -, - CHF -,} - CF 2 -, - CHCl -, - CFCl -, - CCl 2 -

(ii) Branched minimum structural unit:

  The alkylene group is composed of these minimum structural units singly, or linear (i), branched (ii), or a combination thereof. Preferred specific examples will be described later.

  In addition, among the above examples, it is preferable that the base is composed of a constitutional unit that does not contain Cl, because de-HCl reaction with a base does not occur and is more stable.

（式中、Ｒ¹はフッ素原子を有していてもよい、好ましくは炭素数１〜６のアルキル基；Ｒ²はフッ素原子を有していてもよい、好ましくは炭素数１〜４のアルキレン基；ｎ１は１〜３の整数）で示される含フッ素エーテル基があげられる。 More preferred fluorine-containing ether groups include those represented by the formula:

(In the formula, R ¹ may have a fluorine atom, preferably an alkyl group having 1 to 6 carbon atoms; R ² may have a fluorine atom, preferably an alkylene having 1 to 4 carbon atoms. Group; n1 is an integer of 1 to 3).

  More specifically, the following combinations can be exemplified, but are not limited to these.

The (a) R ^1, formula ^{(1): X 8 X 9} X 10 C- (R 4) n2 - (X 8, X 9 and both X ¹⁰ are the same or different H or F; R ⁴ is An alkylene group which may have a fluorine atom having 1 to 5 carbon atoms; n2 is more preferably an alkyl group represented by 0 or 1).

When n2 is 0, it is CH ₃ —, CF ₃ —, HCF ₂ —, H ₂ CF—.

As a specific example when n2 is 1, R ¹ is linear, CF ₃ CH ₂ —, CF ₃ CF ₂ —, CF ₃ CH ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ —, CF ₃ CF ₂ CF _2- , CF ₃ CH ₂ CF _2- , CF ₃ CH ₂ CH ₂ CH _2- , CF ₃ CF ₂ CH ₂ CH _2- , CF ₃ CH ₂ CF ₂ CH _2- , CF ₃ CF ₂ CF _{2 CH 2 -, CF 3 CF} 2 CF 2 CF 2 -, CF 3 CF 2 CH 2 CF 2 -, CF 3 CH 2 CH 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH 2 CH 2 -, CF ₃ CH ₂ CF ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ CF ₂ CH ₂ —, CF ₃ CF _{2 CH 2 CH 2 CH 2 CH} 2 -, CF 3 CF 2 CF 2 CF 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CF 2 CH 2 CH 2 _{, HCF 2 CH 2 -, HCF} 2 CF 2 -, HCF 2 CH 2 CH 2 -, HCF 2 CF 2 CH 2 -, HCF 2 CH 2 CF 2 -, HCF 2 CF 2 CH 2 CH 2 -, HCF 2 CH ₂ CF ₂ CH _2- , HCF ₂ CF ₂ CF ₂ CF _2- , HCF ₂ CF ₂ CH ₂ CH ₂ CH _2- , HCF ₂ CH ₂ CF ₂ CH ₂ CH _2- , HCF ₂ CF ₂ CF ₂ CF ₂ CH _{2 -, HCF 2 CF 2 CF} 2 CF 2 CH 2 CH 2 -, FCH 2 CH 2 -, FCH 2 CF 2 -, FCH 2 CF 2 CH 2 -, FCH 2 CF 2 CH 2 -, CH 3 CF 2 - CH ₃ CH ₂ —, CH ₃ CF ₂ CH ₂ —, CH ₃ CF ₂ CF ₂ —, CH ₃ CH ₂ CH ₂ —, CH ₃ CF ₂ CH ₂ CF ₂ —, CH ₃ CF ₂ CF ₂ CF ₂ — CH ₃ CH ₂ CF ₂ CF ₂ —, CH ₃ CH ₂ CH ₂ CH ₂ —, CH ₃ CF ₂ CH ₂ CF ₂ CH _2- , CH ₃ CF ₂ CF ₂ CF ₂ CH _2- , CH ₃ CF ₂ CF ₂ CH ₂ CH _2- , CH ₃ CH ₂ CF ₂ CF ₂ CH _2- , CH ₃ CF ₂ CH ₂ CF ₂ CH ₂₋ , CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ CH ₂ —, CH ₃ CH ₂ CF ₂ CF ₂ CH ₂ CH ₂ —, CH ₃ CF ₂ CH ₂ CF ₂ CH ₂ CH ₂ — and the like can be exemplified and branched As a chain,

などがあげられる。

Etc.

However, since the viscosity is likely to increase when the branch is —CH ₃ or —CF ₃ , the straight chain type is more preferable.

n1 is an integer of 1 to 3, preferably 1 or 2. When n1 = 2 or 3, R ² may be the same or different.

Preferable specific examples of R ² include the following linear or branched types.

As those of _{linear, -CH 2 -, - CHF -} , - CF 2 -, - CH 2 CH 2 -, - CF 2 CH 2 -, - CF 2 CF 2 -, - CH 2 CF 2 -, _{-CH 2 CH 2 CH 2 -,} - CH 2 CH 2 CF 2 -, - CH 2 CF 2 CH 2 -, - CH 2 CF 2 CF 2 -, - CF 2 CH 2 CH 2 -, - CF 2 CF 2 CH ₂ —, —CF ₂ CH ₂ CF ₂ —, —CF ₂ CF ₂ CF ₂ — and the like can be exemplified.

などがあげられる。

Etc.

Rf ¹ may be a fluorine-containing alkoxy group having 1 to 17 carbon atoms, preferably 1 to 6 carbon atoms.

In particular, formula (2): X ¹¹ X ¹² X ¹³ C— (R ⁵ ) _n4 —O— (X ¹¹ , X ¹² and X ¹³ are the same or different and all are H or F; R ⁵ is preferably one carbon atom. An alkylene group optionally having 5 to 5 fluorine atoms; n4 is 0 or 1; provided that any one of X ¹¹ , X ¹² , X ¹³ or R ⁵ contains a fluorine atom) More preferred are alkoxy groups.

Specific examples of the fluorine-containing alkoxy group include the specific examples shown in the description of R ¹ represented by the formula (1).

Rf ¹ may be a fluorine-containing alkyl group having 2 or more carbon atoms. The number of carbon atoms of the fluorine-containing alkyl group is preferably 2 to 17, more preferably 2 to 7, particularly 2 to 5. If the number of carbons is too large, the low-temperature characteristics are lowered, or the solubility of the electrolyte salt is lowered. When the carbon number is 1, the solubility of the electrolyte salt is lowered as described above, the discharge efficiency is lowered, and further Shows an increase in viscosity.

Especially the formula:
R ²⁰ -R ²¹ -
Wherein R ²⁰ is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R ²¹ is an alkylene group having 1 to 3 carbon atoms; provided that at least one of R ²⁰ and R ²¹ is a fluorine atom. Can be preferably exemplified from the viewpoint of good solubility of the electrolyte salt.

R ²⁰ is an alkyl group having 1 or more carbon atoms which may have a fluorine atom, preferably a linear or branched alkyl group having 1 to 16 carbon atoms, more preferably 1 to 6, particularly 1 to 3 carbon atoms. It is.

R ²⁰ is specifically CH ₃ —, CH ₃ CH ₂ —, CH ₃ CH ₂ CH ₂ —, CH ₃ CH ₂ CH ₂ CH ₂ —,

などの非フッ素系アルキル基；
ＣＦ₃−、ＣＦ₃ＣＨ₂−、ＣＦ₃ＣＦ₂−、ＣＦ₃ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂−、ＣＦ₃ＣＨ₂ＣＦ₂−、ＣＦ₃ＣＨ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＨ₂ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂ＣＦ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＦ₂−、ＣＦ₃ＣＨ₂ＣＨ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＨ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＨＣＦ₂−、ＨＣＦ₂ＣＨ₂−、ＨＣＦ₂ＣＦ₂−、ＨＣＦ₂ＣＨ₂ＣＨ₂−、ＨＣＦ₂ＣＦ₂ＣＨ₂−、ＨＣＦ₂ＣＨ₂ＣＦ₂−、ＨＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＨＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂−、ＨＣＦ₂ＣＦ₂ＣＦ₂ＣＦ₂−、ＨＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂ＣＨ₂−、ＨＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＨＣＦ₂ＣＦ₂ＣＦ₂ＣＦ₂ＣＨ₂−、ＨＣＦ₂ＣＦ₂ＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＦＣＨ₂−、ＦＣＨ₂ＣＨ₂−、ＦＣＨ₂ＣＦ₂−、ＦＣＨ₂ＣＦ₂ＣＨ₂−、ＦＣＨ₂ＣＦ₂ＣＦ₂−、ＣＨ₃ＣＦ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＦ₂−、ＣＨ₃ＣＨ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＨ₂ＣＦ₂−、ＣＨ₃ＣＦ₂ＣＦ₂ＣＦ₂−、ＣＨ₃ＣＨ₂ＣＦ₂ＣＦ₂−、ＣＨ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＦ₂ＣＦ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＨ₃ＣＨ₂ＣＦ₂ＣＦ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＣＨ₃ＣＦ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂−、ＨＣＦＣｌＣＦ₂ＣＨ₂−、ＨＣＦ₂ＣＦＣｌＣＨ₂−、ＨＣＦ₂ＣＦＣｌＣＦ₂ＣＦＣｌＣＨ₂−、ＨＣＦＣｌＣＦ₂ＣＦＣｌＣＦ₂ＣＨ₂−などの直鎖状のものとしての例があげられ、また分岐鎖状のものとしては、

Non-fluorinated alkyl groups such as
CF _3- , CF ₃ CH _2- , CF ₃ CF _2- , CF ₃ CH ₂ CH _2- , CF ₃ CF ₂ CH _2- , CF ₃ CF ₂ CF _2- , CF ₃ CH ₂ CF _2- , CF ₃ CH ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ CH ₂ —, CF ₃ CH ₂ CF ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CF ₂ —, CF _{3 CF 2 CH 2 CF 2 -,} CF 3 CH 2 CH 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH 2 CH 2 -, CF 3 CH 2 CF 2 CH 2 CH 2 -, CF 3 CF 2 CF 2 CH ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ CF ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ CH ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CF _{2 CF 2 CH 2 CH 2 -,} CF 3 CF 2 CH 2 CF 2 CH 2 CH 2 -, HCF 2 -, HCF 2 CH 2 -, HCF 2 CF 2 _{, HCF 2 CH 2 CH 2 -} , HCF 2 CF 2 CH 2 -, HCF 2 CH 2 CF 2 -, HCF 2 CF 2 CH 2 CH 2 -, HCF 2 CH 2 CF 2 CH 2 -, HCF 2 CF 2 CF _{2 CF 2 -, HCF 2 CF} 2 CH 2 CH 2 CH 2 -, HCF 2 CH 2 CF 2 CH 2 CH 2 -, HCF 2 CF 2 CF 2 CF 2 CH 2 -, HCF 2 CF 2 CF 2 CF 2 CH _{2 CH 2 -, FCH 2 -} , FCH 2 CH 2 -, FCH 2 CF 2 -, FCH 2 CF 2 CH 2 -, FCH 2 CF 2 CF 2 -, CH 3 CF 2 CH 2 -, CH 3 CF 2 CF _{2 -, CH 3 CH 2 CH} 2 -, CH 3 CF 2 CH 2 CF 2 -, CH 3 CF 2 CF 2 CF 2 -, CH 3 CH 2 CF 2 CF 2 -, CH 3 CF 2 CH 2 CF 2 CH _{2 -, CH 3 CF 2 CF} 2 CF 2 CH 2 -, CH 3 CF 2 CF 2 CH 2 CH 2 -, C _{3 CH 2 CF 2 CF 2 CH} 2 -, CH 3 CF 2 CH 2 CF 2 CH 2 -, CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -, CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 - , HCFClCF ₂ CH _2- , HCF ₂ CFClCH _2- , HCF ₂ CFClCF ₂ CFClCH _2- , HCFClCF ₂ CFClCF ₂ CH _2-, etc. ,

などの含フッ素アルキル基が好ましくあげることができる。ただし、−ＣＨ₃や−ＣＦ₃という分岐を有していると粘性が高くなりやすいため、その数は少ない（１個）かゼロの方がより好ましい。

Preferred examples include fluorine-containing alkyl groups such as However, since the viscosity tends to be high if there is a branch of —CH ₃ or —CF ₃ , the number is less (one) or more preferably zero.

R ²¹ is a linear or branched alkylene group having 1 to 3 carbon atoms such as an alkylene group which may have a fluorine atom. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. R ²¹ is composed of these alone or in combination.

(i) Minimum linear structural unit:
_{-CH 2 -, - CHF -,} - CF 2 -, - CHCl -, - CFCl -, - CCl 2 -

(ii) Branched minimum structural unit:

  In addition, among the above examples, it is preferable that the base is composed of a constitutional unit that does not contain Cl, because de-HCl reaction with a base does not occur and is more stable.

Furthermore as R ²¹ is a straight-chain _{type, -CH 2 -, - CH 2} CH 2 - or -CF ₂ -, -CH ₂ from the viewpoint of especially it can be further improved solubility of the electrolyte salt - , —CH ₂ CH ₂ — is preferable.

R ²¹ is a branched type:-(CX ¹⁴ X ¹⁵ )-(X ¹⁴ is H, F, CH ₃ or CF ₃ ; X ¹⁵ is CH ₃ or CF _3, provided that X ¹⁵ is CF ₃ X ¹⁴ is preferably H or CH ₃ ), and these can particularly further improve the solubility of the electrolyte salt.

Preferred fluorine-containing alkyl groups include, for example, CF ₃ CF ₂ —, HCF ₂ CF ₂ —, H ₂ CFCF ₂ —, CH ₃ CF ₂ —, CF ₃ CF ₂ CF ₂ —, HCF ₂ CF ₂ CF ₂ —, H ₂ CFCF ₂ CF ₂ —, CH ₃ CF ₂ CF ₂ —, CF ₃ CH ₂ —, HCF ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ —, HCF ₂ CF ₂ CH ₂ —, H ₂ CFCF ₂ CH ₂ — _{, CH 3 CF 2 CH 2 -} , CF 3 CF 2 CF 2 CH 2 -, CF 3 CF 2 CF 2 CF 2 CH 2 -, HCF 2 CF 2 CF 2 CH 2 -, H 2 CFCF 2 CF 2 CH 2 - _{, CH 3 CF 2 CF 2 CH} 2 -, CF 3 CH 2 CH 2 -, HCF 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH 2 -, HCF 2 CF 2 CH 2 CH 2 -, H 2 CFCF _{2 CH 2 CH 2 -, CH} 3 CF 2 CH 2 CH 2 -, CF 3 CF 2 CF 2 CH 2 _{H 2 -, HCF 2 CF 2} CF 2 CH 2 CH 2 -, H 2 CFCF 2 CF 2 CH 2 CH 2 -, CH 3 CF 2 CF 2 CH 2 CH 2 -,

Specific examples of preferred fluorine-containing alkyl groups in which R ²¹ is a linear type include, for example, CF ₃ CH ₂ —, HCF ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ —, HCF ₂ CF ₂ CH ₂ —, H ₂ CFCF ₂ CH _2- , CH ₃ CF ₂ CH _2- , CF ₃ CF ₂ CF ₂ CH _2- , HCF ₂ CF ₂ CF ₂ CH _2- , H ₂ CFCF ₂ CF ₂ CH _2- , CH ₃ CF ₂ CF ₂ CH _{2 -, CF 3 CH 2 CH} 2 -, HCF 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH 2 -, HCF 2 CF 2 CH 2 CH 2 -, H 2 CFCF 2 CH 2 CH 2 -, CH ₃ CF ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CF ₂ CH ₂ CH ₂ —, HCF ₂ CF ₂ CF ₂ CH ₂ CH ₂ —, H ₂ CFCF ₂ CF ₂ CH ₂ CH ₂ —, CH ₃ CF ₂ CF ₂ CH ₂ CH _2- ,

などがあげられる。

Etc.

Specific examples of preferred fluorine-containing alkyl groups in which R ²¹ is branched include, for example:

などがあげられる。

Etc.

In the fluorine-containing lactone (I), X ¹ and X ² are the same or different and all are H, F, Cl, CF ₃ or CH ₃ , and X ³ is H, F, Cl or a hydrogen atom is a halogen atom It is an alkyl group which may be substituted and may contain a hetero atom in the chain.

X ¹ and X ² are preferably H, F, or Cl because it is desirable that the bulk of the molecule is smaller. In particular, in the group or atom having a high electron-withdrawing effect, H is most preferable because the coordination ability of the fluorinated lactone tends to decrease and the solubility of the electrolyte salt and the ionic conductivity tend to decrease.

When X ³ is an alkyl group in which a hydrogen atom may be substituted with a halogen atom and a hetero atom may be contained in the chain, a preferred specific example thereof is preferably a straight chain having 1 to 15 carbon atoms or A branched unsubstituted alkyl group, more preferably a linear or branched unsubstituted alkyl group having 1 to 4 carbon atoms; preferably a fluorinated alkyl having 1 to 15 carbon atoms, more preferably 1 to 4 carbon atoms Group; the same fluorine-containing ether group as Rf ¹ above; preferably a linear or branched non-fluorinated ether group having 1 to 15 carbon atoms, more preferably 1 to 4 carbon atoms.

Examples of the linear or branched unsubstituted alkyl group include CH ₃ —, C ₂ H ₅ —, C ₃ H ₇ —, C ₄ H ₉ —, (CH ₃ ) ₂ CH—, CH ₃ C (CH ₃ ) _2- and the like.

Examples of the fluorine-containing alkyl group include CF _3- , CF ₃ CH _2- , CF ₃ CF _2- , CF ₃ CF ₂ CH _2- , CF ₃ CF ₂ CF _2- , CF ₃ CH ₂ CF _2- , CF ₃ CH _{2 CH 2 -, CF 3 CF} 2 CH 2 CH 2 -, CF 3 CF 2 CF 2 CH 2 -, CF 3 CF 2 CF 2 CF 2 -, CF 3 CH 2 CF 2 CH 2 -, HCF 2 CF 2 CH _2- , FCH ₂ CF ₂ CF ₂ —, FCH ₂ CF ₂ CH ₂ —, HCF ₂ CF ₂ CF ₂ CF ₂ CH ₂ — and the like can be exemplified.

などがあげられ、特に末端がＨＣＦ₂またはＣＦ₃であるものが、低粘度化に進む点からさらに好ましい。

In particular, those having a terminal HCF ₂ or CF ₃ are more preferable from the viewpoint of lowering the viscosity.

Particularly preferred among X ³ are H, F, Cl, CF ₃ , and CH ₃ since the bulk of atoms or molecules is small, and further H or F.

When Rf ¹ is a fluorine-containing alkyl group, X ¹ , X ² and X ³ are all preferably H, but when X ³ is a fluorine-containing alkyl group, the content of Rf ¹ is It may be the same as or different from the fluorine alkyl group.

  Specific examples of the fluorine-containing ether group include the above-mentioned fluorine-containing ether groups.

Examples of the linear or branched non-fluorinated ether group include CH ₃ CH ₂ —OCH ₂ CH ₂ —, CH ₃ —OCH ₂ CH ₂ —, CH ₃ CH (CH ₃ ) —OCH ₂ CH ₂ — and the like. Examples of the fluorine-containing ether group having a linear or branched terminal CF ₃ at the end include, for example, C ₃ F ₇ —OCF (CF ₃ ) CH ₂ —, C ₃ F ₇ —OCF (CF ₃ ) CF _{2 -, CF 3 CH 2 -OCH 2} CH 2 -, CF 3 -OCH 2 CH 2 -, CF 3 CF 2 CH 2 -OCH 2 CH 2 -, CF 3 CH (CF 3) -OCH 2 CH 2 - and can give.

In the present invention, specific examples of particularly preferred fluorine-containing ether group-containing fluorine-containing lactones and fluorine-containing alkoxy group-containing fluorine-containing lactones are given below, but the present invention is not limited thereto. In each formula, either one of A and B is a carbon atom in which the bonded hydrogen atom is substituted or unsubstituted, preferably CX ⁶ X ⁷ (X ⁶ and X ⁷ are the same as in formula (I) ) And the other is an oxygen atom.

In the present invention, specific examples of particularly preferred fluorine-containing alkyl group-containing fluorine-containing lactones are listed below, but the present invention is not limited to these. In each formula, either one of A and B is a carbon atom in which the bonded hydrogen atom is substituted or unsubstituted, preferably CX ⁶ X ⁷ (X ⁶ and X ⁷ are the same as in formula (I) ) And the other is an oxygen atom.

  Among these, a fluorine-containing lactone in which A is an oxygen atom and B is a carbon atom is preferable from the viewpoint of easy synthesis.

Rf ¹ is a fluorine-containing ether group, the synthesis of the fluorine-containing lactone 5- fluorinated alkoxy group, or carbon atoms at two or more fluorine-containing alkyl group, exemplified is a method of the following (1) to (6) However, it is not limited to these, and may be changed as appropriate.

In the formula (I), when X ¹ , X ² and X ³ are all H, the formula (Ia):
Rf ¹ -OH (Ia)
A method of subjecting the fluorinated alcohol (Ia) represented by the formula (wherein Rf ¹ is the same as above) to the next reaction can be exemplified.

(1) Formula (Ib) in the presence of a base catalyst:

と含フッ素アルコール（Ｉ−ａ）を求核置換する。

And fluorinated alcohol (Ia).

(2) Formula (Ic) in the presence of an acid catalyst:

と含フッ素アルコール（Ｉ−ａ）を脱水縮合する。

And fluorinated alcohol (Ia) are subjected to dehydration condensation.

(3) Rf ¹ I and CH ₂ = CHCH ₂ CH ₂ COOH are radically reacted to obtain Rf ¹ CH ₂ CHICH ₂ CH ₂ COOH. Thereafter, the adduct is cyclized in the presence of a base to obtain a fluorine-containing lactone compound.

(4) Formula (Id):

（式中、Ｒ³はエーテル基を含んでいてもよい炭素数１〜１５のアルキレン基）のエポキシ化合物と含フッ素アルコール（Ｉ−ａ）を求核置換して式（Ｉ−ｅ）：

(Wherein R ³ is an alkylene group having 1 to 15 carbon atoms which may contain an ether group) and a fluorine-containing alcohol (Ia) are subjected to nucleophilic substitution to give a formula (Ie):

を得た後、含フッ素エポキシ化合物（Ｉ−ｅ）とマロン酸ジエチルを塩基存在下で反応を行いラクトンを合成する。その後アルカリ金属水酸化物と塩を形成し脱炭酸後、酸処理を行い対応するラクトン化合物を合成する。

Then, the fluorinated epoxy compound (Ie) and diethyl malonate are reacted in the presence of a base to synthesize a lactone. Thereafter, a salt with an alkali metal hydroxide is formed, and after decarboxylation, acid treatment is performed to synthesize a corresponding lactone compound.

  As another synthesis method of the epoxy compound (Ie) used in the synthesis method (4), for example, the following method may be mentioned.

とし、ついでこれらに

And then to these

（式中、Ｒはアルキル基またはＨ）
を反応させれば、

(Wherein R is an alkyl group or H)
If you react

が得られる。

Is obtained.

As a synthesis method in the case where any ^one of X ¹ , X ² and X ³ is not H in the formula (I), for example, a lactone synthesis method from the epoxy compound of (4) can be employed.

Also,
Rf ¹ —O—R ³ —CH═CH—R
Is oxidized using O ₃ , KMnO ₄ , NaOCl, etc., and the corresponding epoxy compound:

に変換し、ついで上記（４）の方法により含フッ素ラクトンに変換することもできる。

And then converted to a fluorinated lactone by the method (4) above.

Examples of the method for synthesizing a 5-membered fluorinated lactone in which Rf ¹ is a fluorinated alkyl group include the following methods.

(5) Rf ¹ —CH═CH ₂ corresponding to an epoxy compound using O ₃ , KMnO ₄ or NaOCl:

を合成し、ついで上記（４）の方法により含フッ素ラクトンに変換する。

And then converted to a fluorinated lactone by the method of (4) above.

(6) Rf ¹ I and CH ₂ ═CHCH ₂ OR or CH ₂ ═CHCH ₂ OC (═O) R (where R is an alkyl group or H) undergo a radical reaction, and Rf ¹ —CH ₂ ═CHCHICH ₂ OR and Rf ^1- CH ₂ CHICH ₂ OC (═O) R is obtained and then cyclized to give the corresponding epoxy compound:

を合成し、ついで上記（４）の方法により含フッ素ラクトンに変換する。

And then converted to a fluorinated lactone by the method of (4) above.

Of the fluorine-containing lactones represented by the formula (I), a compound in which Rf ¹ is a fluorine-containing ether group or a fluorine-containing alkyl group having 2 or more carbon atoms is a novel compound not described in any literature.

  In the present invention, as a solvent for dissolving an electrolyte salt, in addition to a fluorine-containing lactone (I) having a fluorine-containing ether group or a fluorine-containing alkyl group, one or more other electrolyte salt-dissolving solvents (III) are mixed. May be used.

  Other electrolyte salt dissolving solvents (III) include non-fluorinated solvents such as hydrocarbon carbonate solvents, nitrile solvents, hydrocarbon lactone solvents, ester solvents, and other than fluorine-containing lactones (I). It may be a fluorine-containing solvent, for example, a fluorine-containing carbonate solvent. In particular, when the fluorinated lactone is solid, it is desirable to add another electrolyte salt dissolving solvent (III).

  Examples of the non-fluorine solvent include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane. , Methyl formate, methyl acetate, methyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, acetonitrile, propionitrile, succinonitrile, butyronitrile, isobutyronitrile, benzonitrile, glutaronitrile, dimethyl sulfoxide, methyl pyrrolidone In particular, ethylene carbonate, propylene carbonate, diethyl carbonate, and γ-butyl are used from the viewpoint of improving dielectric constant, oxidation resistance, and electrochemical stability. Examples include tyrolactone, 1,2-dimethoxyethane, 1,3-dioxolane, acetonitrile, propionitrile, succinonitrile, butyronitrile, isobutyronitrile, and glutaronitrile, and dielectric constant and oxidation resistance are particularly preferable.

  Examples of the fluorine-containing solvent other than the fluorine-containing lactone (I) are described in JP-A-06-219992, JP-A-10-149840, JP-A-2001-256983, 2000-327634, and the like. Fluorine-containing carbonates; fluorine-containing lactones described in JP-A-11-195429, JP-A-07-283083, JP-A-2001-256983, JP-A-2003-163031, and the like; Fluorinated ethers such as JP 06-176768, JP 08-37024, JP 11-307123, JP 2000-294281, and the like can be used. -219992 and JP-A-2001-256983 Fluorinated ethers have been described in carbonates and the patent publications are preferred.

  In addition, the formula:

（式中、Ｒｆ^1aは、式：

(Wherein Rf ^1a represents the formula:

（式中、Ｘ^1aおよびＸ^2aは同じかまたは異なりＨまたはＦ）で示される部位を末端に有しかつフッ素含有率が１０〜７６質量％であるフルオロアルキル基；Ｒｆ^2aは前記式で示される部位または−ＣＦ₃を末端に有しかつフッ素含有率が１０〜７６質量％であるフルオロアルキル基）で示される鎖状カーボネート；
式：

(Wherein X ^1a and X ^2a are the same or different H or F), and a fluoroalkyl group having a terminal and a fluorine content of 10 to 76% by mass; Rf ^2a is represented by the above formula Or a linear carbonate having a —CF ₃ terminal and a fluoroalkyl group having a fluorine content of 10 to 76% by mass;
formula:

（式中、Ｒｆ^1bはＣＦ₃を末端に有しかつフッ素含有率が１０〜７６質量％である含フッ素エーテル基；Ｒｆ^2bはフッ素含有率が１０〜７６質量％である含フッ素エーテル基または含フッ素アルキル基）で示される鎖状カーボネート；
式：

(In the formula, Rf ^1b is a fluorine-containing ether group having a CF ₃ terminal and a fluorine content of 10 to 76% by mass; Rf ^2b is a fluorine-containing ether group having a fluorine content of 10 to 76% by mass or A linear carbonate represented by a fluorine-containing alkyl group);
formula:

（式中、Ｒｆ^1cは式：
ＨＣＦＸ^1c−
（式中、Ｘ^1cはＨまたはＦ）で示される部位を末端に有しかつフッ素含有率が１０〜７６質量％である含フッ素エーテル基；Ｒ^1cは水素原子がハロゲン原子で置換されていてもよく、ヘテロ原子を鎖中に含んでいてもよいアルキル基）で示される鎖状カーボネート
なども併用してもよい。特に、高耐電圧が必要なキャパシタ用途では、電解質塩溶解用溶媒(III)として上記の含フッ素鎖状カーボネートを用いることが望ましい。

(In the formula, Rf ^1c the formula:
HCFX ^1c −
(Wherein X ^1c is H or F) and a fluorine-containing ether group having a fluorine content of 10 to 76% by mass at the terminal; R ^1c is a hydrogen atom substituted with a halogen atom Alternatively, a chain carbonate represented by an alkyl group which may contain a hetero atom in the chain may be used in combination. In particular, in a capacitor application requiring a high withstand voltage, it is desirable to use the above-mentioned fluorine-containing chain carbonate as the solvent (III) for dissolving the electrolyte salt.

  Examples of fluorine-containing chain carbonates that can be used in combination include:

において、Ｒｆ^1dおよびＲｆ^2dが、Ｈ（ＣＦ₂）₂ＣＨ₂−、ＦＣＨ₂ＣＦ₂ＣＨ₂−、Ｈ（ＣＦ₂）₂ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ₂ＣＨ₂−、ＣＦ₃ＣＨ₂ＣＨ₂−、ＣＦ₃ＣＦ（ＣＦ₃）ＣＨ₂ＣＨ₂−、Ｃ₃Ｆ₇ＯＣＦ（ＣＦ₃）ＣＨ₂−、ＣＦ₃ＯＣＦ（ＣＦ₃）ＣＨ₂−、ＣＦ₃ＯＣＦ₂−などの含フッ素基を組み合わせた鎖状カーボネートであることが好ましい。

Rf ^1d and Rf ^2d are H (CF ₂ ) ₂ CH ₂ —, FCH ₂ CF ₂ CH ₂ —, H (CF ₂ ) ₂ CH ₂ CH ₂ —, CF ₃ CF ₂ CH ₂ —, CF ₃ CH _{2 CH 2 -, CF 3 CF} (CF 3) CH 2 CH 2 -, C 3 F 7 OCF (CF 3) CH 2 -, CF 3 OCF (CF 3) CH 2 -, CF 3 OCF 2 - containing such A chain carbonate combined with a fluorine group is preferred.

  Also the formula:

（式中、Ｒｆ¹は含フッ素エーテル基、含フッ素アルコキシ基または炭素数２以上の含フッ素アルキル基；Ｘ¹およびＸ²は同じかまたは異なり、いずれもＨ、Ｆ、Ｃｌ、ＣＦ₃またはＣＨ₃；Ｘ³はＨ、Ｆ、Ｃｌまたは水素原子がハロゲン原子で置換されていてもよく、ヘテロ原子を鎖中に含んでいてもよいアルキル基）で示される含フッ素環状カーボネートも併用可能である。

(In the formula, Rf ¹ is a fluorine-containing ether group, a fluorine-containing alkoxy group or a fluorine-containing alkyl group having 2 or more carbon atoms; X ¹ and X ² are the same or different, and any of H, F, Cl, CF ₃ or CH ₃ ; X ³ may be a fluorine-containing cyclic carbonate represented by H, F, Cl, or a hydrogen atom which may be substituted with a halogen atom, or an alkyl group which may contain a hetero atom in the chain. .

  By the way, fluorine-containing ethers are useful because they have excellent nonflammability-improving effects, but have low compatibility with non-fluorinated electrolyte salt dissolving solvents, especially hydrocarbon carbonates such as ethylene carbonate and diethylene carbonate. When a certain amount or more was mixed with the electrolyte salt dissolving solvent, it sometimes separated into two layers. However, when the fluorine-containing lactone (I) coexists, a uniform solution of these three components can be easily formed. This is presumed that the fluorine-containing lactone (I) acts as a compatibilizing agent for compatibilizing the fluorine-containing ether and the solvent for dissolving the non-fluorine-based electrolyte salt. In a uniform electrolytic solution containing (II), a solvent for dissolving a non-fluorinated electrolyte salt, and a fluorinated ether, further improvement in incombustibility can be expected.

  The amount of the other electrolyte salt dissolving solvent (III) mixed is 1% by mass or more, preferably 10% by mass or more, particularly 20% by mass or more in the total electrolyte salt dissolving solvent. The upper limit is preferably 98% by mass, preferably 90% by mass, and particularly 80% by mass from the viewpoints of flame retardancy, low temperature characteristics, and withstand voltage.

  In particular, a capacitor can cope with a large current density, so that the electrolyte salt concentration in the electrolytic solution is preferably as high as possible. From this viewpoint, it is preferable to use a hydrocarbon solvent excellent in solubility of the electrolyte salt, in particular, the above-mentioned fluorine-containing carbonate, propylene carbonate, γ-butyrolactone, acetonitrile, 1,3-dioxolane and the like.

Further, when the working voltage is particularly increased for capacitors, the fluorine-containing lactone itself of the present invention has a high oxidation resistance, and therefore other solvents and electrolyte salts to be combined preferably have a high oxidation resistance. From this point of view, the above-mentioned fluorine-containing carbonate, propylene carbonate, and γ-butyrolactone are particularly preferable as the other solvent, and among the electrolyte salts described later, the anion is BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF _6. ^- can be salts are preferred.

  Next, the electrolyte salt (II) which is the other component of the electrolytic solution of the present invention will be described.

  Examples of the electrolyte salt (II) that can be used in the present invention include conventionally known metal salts, liquid salts (ionic liquids), inorganic polymer salts, organic polymer salts, and the like.

  These electrolyte salts are particularly suitable compounds depending on the intended use of the electrolytic solution. Next, suitable electrolyte salts are illustrated for each application, but are not limited to the illustrated specific examples. In other applications, the following exemplified electrolyte salts can be used as appropriate.

  First, as the metal salt of the lithium secondary battery, various organic metal salts such as boron anion type, oxygen anion type, nitrogen anion type, carbon anion type, and phosphorus anion type can be used. Is preferably used.

Specific examples of the oxygen anion type include CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, C ₈ F ₁₇ SO ₃ Li, CH ₃ SO ₃ Li, C ₆ H ₅ SO ₃ Li, and LiSO ₃ C. ₂ F ₄ SO ₃ Li, CF ₃ CO ₂ Li, C ₆ H ₅ CO ₂ Li, Li ₂ C ₄ O ₄ or the like may be used, and in particular, CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, C It is preferable to use ₈ F ₁₇ SO ₃ Li.

Nitrogen anion types include (CF ₃ SO ₂ ) ₂ NLi (TFSI), (C ₂ F ₅ SO ₂ ) ₂ NLi (BETI), (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) NLi, (CF ₃ SO ₂ ) (C ₈ F ₁₇ SO ₂ ) NLi, (CF ₃ CO) ₂ NLi, (CF ₃ CO) (CF ₃ CO ₂ ) NLi, ((CF ₃ ) ₂ CHOSO ₂ ) ₂ NLi, (C ₂ F ₅ CH ₂ OSO ₂ ) ₂ NLi or the like may be used, and (CF ₃ SO ₂ ) ₂ NLi (TFSI) or (C ₂ F ₅ SO ₂ ) ₂ NLi (BETI) is particularly preferable.

The inorganic metal _{salt, LiPF 6, LiBF 4, LiAsF} 6, LiSbF 6, can be used as LiClO _4, in particular, it is preferable to use LiPF _6, LiBF _4.

For capacitors, the organometallic salt is (Me) _x (Et) _y N (Me is methylene, Et is ethylene, x and y are the same or different and are integers from 0 to 4 and x + y = 4) The quaternary ammonium salts shown, specifically 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 MeBF 4, Et 3 MeClO 4, Et 3 MePF 6, Et 3 MeAsF 6, Et 3 MeSbF 6, Et 3 MeCF 3 SO 3, Et 3 Me ( CF ₃ SO ₂ ) ₂ N, Et ₃ MeC ₄ F ₉ SO ₃ may be used, and Et ₄ NBF ₄ , Et ₄ NPF ₆ , Et ₄ NSbF ₆ , and Et ₄ NAsF ₆ are particularly preferable.
Of the tetraalkyl quaternary ammonium salts, it is desirable to use a quaternary ammonium salt in which one or two of the alkyl groups are ethers from the viewpoint of viscosity reduction. For example, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium salt is preferable because of its low viscosity. A spirobipyrrolidinium salt or a salt in which hydrogen atoms of spirobipyridinium are partially substituted with fluorine atoms is also preferable because of low viscosity and particularly excellent low-temperature characteristics. Further, among the tetraalkyl quaternary ammonium salts, those in which the alkyl group is one or more fluorine-containing alkyl groups or fluorine-containing ether groups are preferable from the viewpoint of improving oxidation resistance and reducing viscosity. Furthermore, an imidazolium salt containing a fluorine atom, a fluorine-containing alkyl group, or a fluorine-containing ether group is also preferred from the viewpoint of improving oxidation resistance and reducing viscosity. As the anion species of the salt, BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ and SbF ₆ ⁻ having excellent oxidation resistance are preferable.

As the inorganic metal salt, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , NaPF ₆ , NaBF ₄ , NaAsF ₆ , NaClO ₄ , KPF ₆ , KBF ₄ , KAsF ₆ , KClO _4, etc. can be used. in _{particular, LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6, NaPF 6, it is preferable to use a NaBF _4.

For dye-sensitized solar cells, R ⁶ R ⁷ R ⁸ R ⁹ NI (R ^{6 to} R ⁹ are the same or different and are alkyl groups having 1 to 3 carbon atoms), LiI, NaI, KI,

などが例示できる。

Etc. can be exemplified.

When a liquid salt is used as the electrolyte salt (II), organic and inorganic anions and polyalkylimidazolium cations, N-alkylpyridinium cations, tetrasalts are used for lithium secondary batteries, capacitors, and dye-sensitized solar cells. Examples thereof include salts with alkylammonium cations, tetraalkylammonium cations containing an ether chain, tetraalkylphosphonium cations, and spirobipyrrolidinium cations, particularly 1,3-dialkylimidazolium salts, spirobipyrrolidinium salts, Alkyl ammonium salts containing ether chains are preferred. In addition, a salt in which a part of the cation of the salt is substituted with fluorine is desirable from the viewpoint of viscosity reduction and oxidation resistance improvement.

Examples of polyalkylimidazolium cations include 1,3-dialkylimidazolium cations such as 1-ethyl-3-methylimidazolium cation (EMI ⁺ ) and 1-butyl-3-methylimidazolium cation (BMI ⁺ ); Trialkylimidazolium cations such as 2-dimethyl-3-propylimidazolium cation (DMPI ⁺ ) are preferred. Further, those in which some of these hydrogen atoms are substituted with fluorine are desirable.

Preferred inorganic anions include, for example, AlCl ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , I ^{− and the} like, and organic anions include, for example, CH ₃ COO ⁻ , CF ₃ COO ⁻ , C ₃ F ₇ COO ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ^{− and the} like can be mentioned.

Specific examples include EMIAlCl ₄ , EMIBF ₄ , EMIPF ₆ , EMIAsF ₆ , EMII, EMICH ₃ COO, EMCF ₃ COO, EMIC ₃ F ₇ COO, EMCF ₃ SO ₃ , EMIC ₄ F ₉ SO ₃ , EMI (CF ₃ SO ₂ ) ₂ N, EMI (C ₂ F ₅ SO ₂ ) ₂ N, BMIAlCl ₄ , BMIBF ₄ , BMIPF ₆ , BMIAsF ₆ , BMII, BMICH ₃ COO, BMICF ₃ COO, BMIC ₃ F ₇ COO, BMICF ₃ SO ₃ , BMIC ₄ F ₉ SO ₃ , BMI (CF ₃ SO ₂ ) ₂ N, BMI (C ₂ F ₅ SO ₂ ) ₂ N, DMPIAlCl ₄ , DMPIBF ₄ , DMPIPF ₆ , DMPIAsF ₆ , DMPII, DMPICH ₃ COO, DMPICF ₃ COO , DMPIC ₃ F ₇ COO, DMPICF ₃ SO ₃ , DMPIC Examples thereof include ₄ F ₉ SO ₃ , DMPI (CF ₃ SO ₂ ) ₂ N, DMPI (C ₂ F ₅ SO ₂ ) ₂ N, and the like.

  In particular, iodides such as EMII, BMII, and DMPII are suitable for dye-sensitized solar cells.

  The amount of electrolyte salt (II) blended varies depending on the required current density, application, type of electrolyte salt, etc., but 0.1 parts by mass or more, and 1 part by mass or more with respect to 100 parts by mass of the fluorinated lactone (I). In particular, it is preferably 5 parts by mass or more, 200 parts by mass or less, more preferably 100 parts by mass or less, and particularly preferably 50 parts by mass or less.

  The electrolytic solution of the present invention is prepared by dissolving the electrolyte salt (II) in a fluorine-containing lactone (I) or a solvent comprising the fluorine-containing lactone (I) and the electrolyte salt dissolving solvent (III).

  The electrolytic solution of the present invention may be combined with a polymer material that dissolves or swells in the solvent used in the electrolytic solution of the present invention to form a gel (plasticized) gel electrolytic solution.

  Examples of such a polymer material include conventionally known polyethylene oxide and polypropylene oxide, modified products thereof (Japanese Patent Laid-Open Nos. 8-222270 and 2002-140405); 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 Japanese Patent Application No. 2004-301934 can be used.

This ion conductive compound has the formula (1-1):
P- (D) -Q (1-1)
[Wherein D represents the formula (2-1):
-(D1) _n- (FAE) _m- (AE) _p- (Y) _q- (2-1)
(In the formula, D1 represents the formula (2a):

（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；Ｒ¹⁰はＲｆと主鎖を結合する基または結合手）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（２ｂ）：

(Wherein, Rf is crosslinkable functional group a fluorine-containing ether group optionally having; is R ¹⁰ group or a bond that binds the Rf main chain) ether having a fluorine-containing ether group in the side chain represented by unit;
FAE is represented by formula (2b):

（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；Ｒ¹¹はＲｆａと主鎖を結合する基または結合手）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（２ｃ）：

(Wherein, Rfa is hydrogen atom, a crosslinkable functional group which may have a fluorine-containing alkyl group; R ¹¹ is a group or a bond coupling the Rfa main chain) a fluorine-containing alkyl group in its side chain represented by Ether units having:
AE is the formula (2c):

（式中、Ｒ¹³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または架橋性官能基を有していてもよい芳香族炭化水素基；Ｒ¹²はＲ¹³と主鎖を結合する基または結合手）で示されるエーテル単位；
Ｙは、式（２ｄ−１）〜（２ｄ−３）：

(Wherein R ¹³ has a hydrogen atom, an alkyl group which may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group which may have a crosslinkable functional group, or a crosslinkable functional group. An aromatic hydrocarbon group which may be substituted; R ¹² is an ether unit represented by R ¹³ and a group or a bond which bonds the main chain;
Y represents formulas (2d-1) to (2d-3):

A unit comprising at least one of
n is an integer from 0 to 200; m is an integer from 0 to 200; p is an integer from 0 to 10000; q is an integer from 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 A group, —OR ¹⁴ (R ¹⁴ 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 when D is terminated with an oxygen atom) Group, —OR ¹⁴ , not an ester group and a carbonate group)], and an amorphous fluorine-containing polyether compound having a fluorine-containing group in the side chain.

  You may mix | blend another additive with the electrolyte solution of this invention as needed. Examples of other additives include metal oxides and glass.

  In addition, it is preferable that the electrolyte solution of this invention does not freeze at low temperature (for example, 0 degreeC or -20 degreeC), or electrolyte salt precipitates. 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 electrolyte solution of the present invention is suitable as an electrolyte solution for electrochemical devices because it can simultaneously improve flame retardancy, low temperature characteristics, withstand voltage, solubility of electrolyte salts, and compatibility with hydrocarbon solvents. .

  That is, this invention relates also to the electrochemical device provided with said electrolyte solution. Electrochemical devices include lithium secondary batteries, capacitors (electrolytic double layer capacitors), radical batteries, solar cells (especially dye-sensitized solar cells), fuel cells, various electrochemical sensors, electrochromic devices, and electrochemical switching devices. , Aluminum electrolytic capacitors, tantalum electrolytic capacitors, and the like, and lithium secondary batteries, electrolytic double layer capacitors, and particularly electric double layer capacitors having a withstand voltage of 3.5 V or more are preferable. A high-capacity electric double layer capacitor is required to have a withstand voltage of 3.0 V or more, but the electric double layer capacitor of the present invention sufficiently satisfies the requirement.

  In addition, the electrolytic solution of the present invention can also be used as an ionic conductor of an antistatic coating material.

  Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to such examples.

  In addition, the measuring method employ | adopted by this invention is as follows.

(1) NMR: 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) IR:
Measure at room temperature with a Fourier transform infrared spectrophotometer 1760X manufactured by Perkin Elmer.

(3) Gas chromatography apparatus: GC17A GAS CHROMATOGRAPH (manufactured by Shimadzu Corporation)
Measurement conditions: After holding at 100 ° C. for 5 minutes, the temperature is raised to 230 ° C. at 20 ° C./minute and held at 230 ° C. for 10 minutes.
Column used: DB624

(4) Fluorine content 10 mg of the sample is burned by the oxygen flask combustion method, the decomposition gas is absorbed in 20 ml of deionized water, and the fluorine ion concentration in the absorption liquid is determined by the fluorine selective electrode method (fluorine ion meter, model 901 manufactured by Orion). ) To obtain (mass%).

Synthesis example 1
The reaction was carried out using a stainless steel 500 ml autoclave. Azoisobutyronitrile (AIBN) (840 mg: 5 mmol) and 4-pentenoic acid (25 g: 250 mmol) were added to the autoclave, the autoclave was cooled using a dry ice-acetone solution, and the system was evacuated.

Thereafter, C ₂ F ₅ I (67 g: 275 mmol) was liquefied and added. While stirring, the autoclave was returned to room temperature and then heated to 70 ° C. The internal pressure at that time was 0.8 MPa. The reaction was stopped after stirring for 1 hour. The disappearance of 4-pentenoic acid was confirmed by gas chromatography.

The reaction solution was then transferred to a three-necked flask equipped with a 500 ml reflux tube. The reaction solution was heated to 60 ° C., and a K ₂ CO ₃ aqueous solution (34.6 g, water 100 ml) was added dropwise using a dropping funnel. The generation of carbon dioxide was confirmed simultaneously with the dropwise addition.

  The dripping was completed when the generation of carbon dioxide was completed. After the addition, the reaction solution was separated into two phases. The lower layer solution was extracted and distilled. The target product was obtained in 60% yield (32.9 g: 151 mmol).

When this product was analyzed by ¹⁹ F-NMR and ¹ H-NMR analysis, a 5-membered fluorinated lactone having a fluorinated alkyl group in the side chain:

であることが確認された。

It was confirmed that.

¹⁹ F-NMR: (neat): −85.69 ppm (3F), −117.69 to −114.98 ppm (2F)
¹ H-NMR: (neat): 2.33 to 2.51 ppm (1H), 2.76 to 3.08 ppm (5H), 5.18 to 5.28 ppm (1H)

Further, the stretching vibration of the carbonyl group was confirmed at 1789.8 cm ⁻¹ by IR measurement.

  The fluorine content of this fluorine-containing lactone was 43.6% by mass.

Synthesis example 2
The reaction was performed using a SUS 500 ml autoclave. AIBN (771 mg: 4.70 mmol), 4-pentenoic acid (23.62 g: 236 mmol), and (CF ₃ ) ₂ CFI (67 g: 275 mmol) were added to the autoclave. While stirring, heat was then applied to 70 ° C. The internal pressure at that time was 0 MPa. The reaction was stopped after stirring for 1 hour. The disappearance of 4-pentenoic acid was confirmed by gas chromatography. The reaction solution was then transferred to a three-necked flask equipped with a 500 ml reflux tube. The reaction solution was heated to 60 ° C., and an aqueous K ₂ CO ₃ solution (32.0 g, water 80 ml) was added dropwise using a dropping funnel. The generation of carbon dioxide was confirmed simultaneously with the dropwise addition. The dripping was completed when the generation of carbon dioxide was completed. After the addition, the reaction solution was separated into two phases. The lower layer solution was extracted and distilled. The desired product was obtained in a yield of 70% (45.6 g: 170 mmol).

When this product was analyzed by ¹⁹ F-NMR and ¹ H-NMR analysis, a 5-membered fluorinated lactone having a fluorinated alkyl group in the side chain:

であることが確認された。

It was confirmed that.

¹⁹ F-NMR: (neat): -183.7 to -183.5 ppm (1F), -76.6 to -76.5 ppm (2F)
¹ H-NMR: (neat): 1.51 to 2.78 ppm (6H), 4.83 to 4.93 ppm (1H)

Further, the stretching vibration of the carbonyl group was confirmed at 1783.8 cm ⁻¹ by IR measurement.

  The fluorine content of this fluorine-containing lactone was 49.60% by mass.

Comparative Synthesis Example 1
Under a nitrogen atmosphere, sodium ethoxide (86 ml: 245 mmol) and 100 ml of ethanol were stirred in a 500 ml four-necked flask equipped with a reflux tube, a dropping funnel and a thermometer. Subsequently, diethyl malonate (37.5 g: 234 mmol) was dropped and reacted while maintaining at 30 ° C. After the dropwise addition, 1,1,1-trifluoro-2,3-epoxypropane (25 g: 223 mmol) was added dropwise. When the exotherm subsided, the temperature of the reactor was raised to 80 ° C. and stirred for 30 minutes. Next, a KOH solution (16 g: 285 mmol) was added dropwise. At this time, generation of gas was confirmed. When no more gas was generated, the temperature was lowered and the reaction solution was poured into a HCl solution. At this time, it was confirmed to be acidic. Extraction with ethyl acetate was performed, and the solvent was distilled off, followed by purification by distillation. The desired product was obtained in a yield of 40% (12 g: 78 mmol; boiling point = 64 ° C./3 mmHg).

This product was analyzed by ¹⁹ F-NMR and ¹ H-NMR analysis. As a result, the fluorine-containing lactone containing a fluorine-containing alkyl group having 1 carbon atom in which CF ₃ was directly bonded to the fluorine-containing lactone:

であることが確認された。

It was confirmed that.

¹⁹ F-NMR: (neat): −79.29 to −79.26 ppm (3F)
¹ H-NMR: (neat): 2.28 to 2.43 ppm (1H) 2.55 to 2.70 ppm (3H), 5.01 to 5.14 pp (1H)

Further, the stretching vibration of the carbonyl group was confirmed at 1801 cm ⁻¹ by IR measurement.

  This fluorine-containing lactone had a fluorine content of 37.0% by mass.

Comparative Synthesis Example 2
In a 500 ml autoclave, succinic anhydride (20 g: 0.20 mol), zinc (26.7 g: 0.41 mmol), BrCH ₂ CH ₂ Br (1 drop), I ₂ (0.25 g: 0.98 mmol), CH ₃ CN (152 g) and pyridine (64 g: 0.80 mmol) were added, and the reaction vessel was evacuated and stirred in that state for 5 minutes. _{Then, CF 3 I (90g: 563mmol} ) was introduced. At this time, the reaction temperature exothermed to 50 ° C. Thereafter, the contents were taken out after stirring for about 1.5 hours while maintaining the temperature at 10 to 20 ° C. To the reaction solution taken out, ethyl acetate (300 ml) was added, stirred and filtered to remove zinc. Subsequently, it was quenched with 1N-HCl solution three times, and the upper layer was collected by liquid separation. The collected upper layer was concentrated by an evaporator and analyzed by gas chromatography. Subsequently, the concentrated solution was distilled. The target product was obtained by distillation in a yield of 20% (8.8 g).

This product was analyzed by ¹⁹ F-NMR and ¹ H-NMR analysis. As a result, the fluorine-containing lactone containing a fluorine-containing alkyl group having 1 carbon atom in which CF ₃ was directly bonded to the fluorine-containing lactone:

であることが確認された。

It was confirmed that.

¹⁹ F-NMR: (neat): −77.93 to −77.90 ppm (6F)
¹ H-NMR: (neat): 3.62-3.81 ppm (4H)

Further, the stretching vibration of the carbonyl group was confirmed at 1825 cm ⁻¹ by IR measurement.

  The fluorine content of this fluorine-containing lactone was 51.33% by mass.

Examples 1-2 and Comparative Examples 1-2
Viscosity and base resistance tests were examined for the fluorinated lactones having a fluorinated alkyl group obtained in Synthesis Examples 1 and 2 and the fluorinated alkyl group-containing fluorinated lactones obtained in Comparative Synthesis Examples 1 and 2, respectively. Further, LiN (SO ₂ C ₂ F ₅ ) ₂ as an electrolyte salt was added to the above solution so as to have a concentration of 1 mol / liter, thereby preparing an electrolytic solution. With respect to this electrolytic solution, the withstand voltage and the solubility of the electrolyte salt were examined. The results are shown in Table 1.

Withstand voltage:
Electrolytic solution was applied to a three-electrode voltage measuring cell (working electrode, counter electrode: platinum (where the area ratio of the counter electrode and working electrode is 5: 1), reference electrode: Ag, HS cell manufactured by Hosen Co., Ltd.) Then, the potential is pulled at 3 mV / sec with a potentiostat, and the range where the decomposition current does not flow more than 0.1 mA is defined as the withstand voltage (V).

viscosity:
Using a B-type rotational viscometer (VISCONE CV series manufactured by Tokai Yagami Co., Ltd.), measure the viscosity of the solution at a rotational speed of 60 rpm, temperature of 25, 0, and -20 ° C using a cone with a measured viscosity range of 1 to 500 mPa · s. To do.

Solubility of electrolyte salt:
LiN (SO ₂ C ₂ F ₅ ) ₂ and tetraethylammonium tetrafluoroborate [(C ₂ H ₅ ) ₄ NBF ₄ ] were added to the solution so as to be 1 mol / liter at room temperature, and the mixture was stirred well. The solubility is visually observed.
○: Dissolved uniformly.
Δ: Slightly suspended.
X: Insoluble matter precipitated.

Base resistance test:
A 10% by weight aqueous K ₂ CO ₃ solution and a fluorine-containing lactone are mixed in a sample bottle at a volume ratio of 1: 1 and stirred. The state of the solution after stirring for 1 hour is examined visually.
○: Not decomposed, but separated into two layers.
X: Decomposes into a uniform layer.

  Regarding the base resistance test, no change was confirmed for Synthesis Examples 1 and 2 and Comparative Synthesis Example 2, but Comparative Synthesis Example 1 was colored purple and the solution was uniform. Analysis revealed that it was decomposed.

Example 3
A coin-type lithium secondary battery was produced by the following method.

(Preparation of positive electrode)
As a positive electrode active material, LiCoO ₂ (85% by mass) was added with carbon black (6% by mass) and polyvinylidene fluoride (trade name KF-1000 manufactured by Kureha Chemical Co., Ltd.) (9% by mass) and mixed. A slurry dispersed with methyl-2-pyrrolidone was used, which was uniformly coated on a positive electrode current collector aluminum foil having a thickness of 20 μm, dried, and then punched into a disk shape having a diameter of 12.5 mm. It was.

(Preparation of negative electrode)
Styrene-butadiene rubber (SBR) dispersed with distilled water in 94% by weight of artificial graphite powder (trade name KS-44 manufactured by Temcal Co.) was added to a solid content of 6% by weight and mixed with a disperser. The slurry was uniformly applied onto a negative electrode current collector 18 μm thick copper foil, dried, and then punched into a disk shape having a diameter of 12.5 mm to obtain a negative electrode.

(Production of coin-type lithium secondary battery)
The positive electrode is housed in a stainless steel can body that also serves as a positive electrode current collector, and the negative electrode is placed thereon via a polyethylene separator impregnated with various electrolytic solutions shown below. The coin-type lithium secondary battery was manufactured by caulking and sealing the sealing plate covering the negative electrode current collector with an insulating gasket.

Example 4
Ethanol was added and kneaded to a 8: 1: 1 mixture of phenol resin activated carbon having a specific surface area of 2000 m ² / g activated with water vapor, polytetrafluoroethylene (PTFE), and carbon black. After forming this into a sheet shape, it was roll-rolled to a thickness of 0.6 mm, and the obtained sheet was punched into a disk having a diameter of 12 mm to produce an electrode.

This disk-shaped electrode was bonded to the inside of the positive electrode side and the negative electrode side of a stainless steel case serving as a current collector / housing member of a coin-type cell using a graphite-based adhesive. Next, this stainless steel case was heat-treated at 200 ° C. under reduced pressure to remove moisture, and the compound synthesized in Synthesis Example 2 was dissolved in tetramethylammonium · BF ₄ as an electrolyte salt to a concentration of 1M for electrolysis. A liquid was prepared, and this electrolytic solution was impregnated into a disk-shaped electrode. Next, a polypropylene fiber nonwoven fabric separator (thickness 160 μm, porosity 70%) is sandwiched between both electrodes, and the stainless steel case is caulked and sealed through a gasket as an insulator, and the diameter is 18.4 mm and the thickness is 2. A coin-type electric double layer capacitor of 0 mm was produced.

Claims (10)

Formula (I):

(In the formula, either one of A and B is CX ⁶ X ⁷ (X ⁶ and X ⁷ are the same or different, and any one of H, F, Cl, CF ₃ , CH ₃ or a hydrogen atom is substituted with a halogen atom) And the other is an oxygen atom; Rf ¹ is a fluorinated ether group, a fluorinated alkoxy group or a fluorinated alkyl group having 2 or more carbon atoms; X ¹ and X ² are the same or different, and all are H, F, Cl, CF ₃ or CH ₃ ; X ^{3 to} X ⁵ are the same or different, and all have H, F, Cl, or a hydrogen atom substituted with a halogen atom An electrolyte solution comprising a fluorine-containing lactone (I) represented by n = 0 or 1) and an electrolyte salt (II). The fluorine-containing lactone has the formula (IA):

The electrolytic solution according to claim 1, which is a fluorinated lactone (IA) represented by the formula (wherein A, B, Rf ¹ , X ¹ , X ² and X ³ are the same as those in formula (I)). The fluorine-containing lactone has the formula (IA-1):

The electrolysis according to claim 1 or 2, which is a fluorinated lactone (IA-1) represented by the formula (wherein Rf ¹ , X ¹ , X ² , X ³ , X ⁶ and X ⁷ are the same as those in formula (I)). liquid. In the fluorine-containing lactone, Rf ¹ is represented by the formula:

(Wherein R ¹ is an alkyl group optionally having a fluorine atom; R ² is an alkylene group optionally having a fluorine atom; n 1 is an integer of 1 to 3; provided that R ¹ and R ² The electrolytic solution according to claim 1, wherein at least one of the fluorine-containing ether groups is a fluorine-containing ether group. In the fluorine-containing lactone, Rf ¹ is represented by the formula:
R ²⁰ -R ²¹ -
(Wherein R ²⁰ is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R ²¹ is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; provided that R ²⁰ and The electrolytic solution according to claim 1, wherein at least one of R ²¹ is a fluorine-containing alkyl group represented by: The electrolyte solution according to any one of claims 1 to 5, wherein in the fluorinated lactone, atoms bonded to carbon atoms constituting the lactone ring are all H except Rf ¹ . The electrolyte solution according to any one of claims 1 to 6, which has a viscosity at 0 ° C of 30 mPa · sec or less. The electrolyte solution according to any one of claims 1 to 7, which has a viscosity at -20 ° C of 40 mPa · sec or less. An electrochemical device comprising the electrolytic solution according to claim 1. An electric double layer capacitor comprising the electrolytic solution according to claim 1 and having a withstand voltage of 3.5 V or more.