JP2015170456A - Electrolytic solution and lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an electrolytic solution for electrochemical devices which is superior in battery characteristics (including charge and discharge characteristics) and achieves high safety; and a lithium ion secondary battery.SOLUTION: An electrolytic solution comprises: a nonaqueous solvent; an electrolyte; and a compound expressed by the following general formula (1). Rf-R-X-Ar-Z-Ar'-X'-R'-Rf' (1) (In the general formula (1), Rf and Rf' independently represent a substituted or unsubstituted perfluoroalkyl group having a main chain with 2-18 carbon atoms; R and R' independently represent a substituted or unsubstituted divalent carbon hydride group having a single bond or a main chain with 1-8 carbon atoms; X and X' independently represent a sulfur atom, an oxygen atom, a SO group or a SOgroup, provided that X and X' are different from each other; Ar and Ar' independently represent a substituted or unsubstituted aromatic group or alicyclic group of which the number of atoms forming a ring is 5-20, provided that Ar and Ar' are different from each other; and Z represents a substituted or unsubstituted divalent carbon hydride group or oxy carbon hydride group, which has a main chain with 1-8 carbon atoms.)

Description

  The present invention relates to an electrolytic solution and a lithium ion secondary battery.

Conventionally, low molecular weight or high molecular weight organic gelling agents have been used in various industrial fields to solidify organic liquids. As low molecular weight organic gelling agents, for example, low molecular weight compound groups having hydrogen-bonding functional groups such as amino groups, amide groups, and urea groups in the molecule are known, such as cosmetics, cosmetics, and sludge treatments. It is suitably used in the field.
On the other hand, examples of the high molecular weight organic gelling agent include a group of polymer compounds having a three-dimensional network structure in the molecule. For example, polyether compounds are well known.
There are many examples of studies on high molecular weight organic gelling agents, which are being developed in various fields.

  Development of low molecular weight organic gelling agents is relatively slow compared to high molecular weight ones, and there are few types of known gelling agents. For example, dialkylurea derivatives (see, for example, Patent Document 1), Fluoroalkyl derivatives (see, for example, Patent Documents 2 to 3 and Non-Patent Document 1) are known.

JP-A-8-231942 International Publication No. 2007/083843 International Publication No. 2009/078268

J. et al. Fluorine. Chem. 111, 47-58 (2001)

At present, electrochemical devices using organic liquids are used in various applications, and typical examples thereof include lithium ion secondary batteries that are mainly used as rechargeable batteries for portable devices.
Further, in recent years, there has been a demand for energy saving due to increasing interest in the environment, and there are increasing expectations for various electrochemical devices using organic liquids that can contribute to this demand.
However, when applying an organic liquid electrolyte to an electrochemical device, further improvement of its safety is a major issue. For example, lithium ion secondary batteries are expected to be widely used in the near future for automotive applications, and higher battery safety (non-leakage, flame retardancy, dendride suppression, etc.) is required. Therefore, for example, development of a polymer (gel) battery, a battery using an ionic liquid or a fluoro solvent as an electrolytic solution, and the like has been advanced. However, at present, safety and battery characteristics (charge / discharge characteristics, low temperature operation, high temperature durability, etc.) are in a trade-off relationship. A polymer (gel) battery is expected from the viewpoint of battery size reduction and increased freedom of form in addition to battery safety, but existing dry polymer batteries cannot be said to have high battery characteristics. In addition, although the gel polymer battery has an effect of improving battery characteristics (particularly rate characteristics) as compared with the dry polymer battery, it does not reach the battery using the existing non-aqueous liquid electrolyte.

At present, there are few research examples of electrolytes and secondary batteries using low molecular weight organic gelling agents, which are not sufficient. For example, Patent Document 2 proposes an electrolytic solution using a low molecular weight organic gelling agent, but there is still room for improvement in battery performance even when this electrolytic solution is used.
The present invention has been made in view of the above circumstances, and provides an electrolytic solution for an electrochemical device and a lithium ion secondary battery that is excellent in battery characteristics (such as charge / discharge characteristics) and at the same time realizes high safety. For the purpose.

  In order to achieve the above-mentioned object, the present inventors examined the possibility of applying low molecular weight organic gelling agents including those described in the above-mentioned patent documents to an electrolytic solution and a lithium ion secondary battery. As a result, it was found that a specific low molecular weight organic gelling agent having a plurality of perfluoroalkyl groups is useful as an electrolytic solution and can form a gel electrolyte with high performance. Furthermore, when producing a secondary battery using this electrolyte solution, it discovered that it was compatible with high discharge capacity and high safety, and came to complete this invention.

That is, the present invention is as follows.
[1]
An electrolytic solution containing a nonaqueous solvent, an electrolyte, and a compound represented by the following general formula (1).
Rf-R-X-Ar-Z-Ar'-X'-R'-Rf '(1)
(In General Formula (1), Rf and Rf ′ each independently represents a substituted or unsubstituted perfluoroalkyl group having 2 to 18 carbon atoms in the main chain, and R and R ′ each independently represent a single bond or A substituted or unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms in the main chain; X and X ′ each independently represent an S atom, an O atom, an SO group or an SO ₂ group; 'Is a different group, Ar and Ar' each independently represents a substituted or unsubstituted aromatic group or alicyclic group having 5 to 20 ring-forming atoms, and Ar and Ar 'are different groups. Yes, Z represents a substituted or unsubstituted divalent hydrocarbon group or oxyhydrocarbon group having 1 to 8 carbon atoms in the main chain.
[2]
The electrolytic solution according to [1], wherein Ar and Ar ′ are each independently a substituted or unsubstituted phenylene group, biphenylene group, terphenylene group, naphthylene group, anthranylene group, or pyridylene group.
[3]
The electrolytic solution according to [1], wherein Ar and Ar ′ are each independently a substituted or unsubstituted phenylene group, biphenylene group, or naphthylene group.
[4]
The electrolyte solution according to any one of [1] to [3], wherein X and X ′ are each independently an S atom, an SO group, or an SO ₂ group.
[5]
Any one of [1] to [4], wherein one of Ar and Ar ′ is a phenylene group, the other is a biphenylene group, one of X and X ′ is an S atom, and the other is an SO ₂ group. The electrolyte solution according to the above.
[6]
The electrolytic solution according to any one of [1] to [5], wherein the electrolytic solution is a gelled gel electrolyte.
[7]
A positive electrode containing a positive electrode active material;
A negative electrode containing a negative electrode active material;
[1] to the electrolyte solution according to any one of [6],
A lithium ion secondary battery comprising:
[8]
The lithium ion secondary battery according to [7], wherein the positive electrode active material includes a lithium-containing compound.
[9]
[7] or [8], wherein the negative electrode active material contains one or more materials selected from the group consisting of metallic lithium, a carbon material, a material containing an element capable of forming an alloy with lithium, and a lithium-containing compound. ] The lithium ion secondary battery as described in.

  ADVANTAGE OF THE INVENTION According to this invention, the electrolyte solution for electrochemical devices and lithium ion secondary battery which are excellent also in battery characteristics (charge / discharge characteristics etc.) and also implement | achieve high safety | security can be provided.

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail.
The electrolytic solution of the present embodiment contains a nonaqueous solvent, an electrolyte, and one or more compounds represented by the following general formula (1) (hereinafter also simply referred to as “perfluoro group-containing compound”). Is.
Rf-R-X-Ar-Z-Ar'-X'-R'-Rf '(1)
(In General Formula (1), Rf and Rf ′ each independently represents a substituted or unsubstituted perfluoroalkyl group having 2 to 18 carbon atoms in the main chain, and R and R ′ each independently represent a single bond or A substituted or unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms in the main chain; X and X ′ each independently represent an S atom, an O atom, an SO group or an SO ₂ group; 'Is a different group, Ar and Ar' each independently represents a substituted or unsubstituted aromatic group or alicyclic group having 5 to 20 ring-forming atoms, and Ar and Ar 'are different groups. Yes, Z represents a substituted or unsubstituted divalent hydrocarbon group or oxyhydrocarbon group having 1 to 8 carbon atoms in the main chain.
Moreover, the lithium ion secondary battery of this embodiment is equipped with the positive electrode containing a positive electrode active material, the negative electrode containing a negative electrode active material, and the electrolyte solution of this embodiment.
Since it is configured as described above, the electrolytic solution or the lithium ion secondary battery of this embodiment is excellent in battery characteristics (charge / discharge characteristics, low temperature operation, high temperature durability, etc.) and at the same time realizes high safety. Can do.

<Electrolyte>
The electrolytic solution according to this embodiment contains (i) a nonaqueous solvent, (ii) an electrolyte, and (iii) a perfluoro group-containing compound.
(I) As a nonaqueous solvent, an aprotic solvent is mentioned, for example, Aprotic polar solvent is preferable. Specific examples thereof include, but are not limited to, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, trans-2,3-butylene carbonate, cis-2,3-butylene carbonate, 1,2-pentylene carbonate. , Trans-2,3-pentylene carbonate, cis-2,3-pentylene carbonate, trifluoromethylethylene carbonate, fluoroethylene carbonate, cyclic carbonate represented by 4,5-difluoroethylene carbonate, γ-butyrolactone, γ -Lactone represented by valerolactone; cyclic sulfone represented by sulfolane; cyclic ether represented by tetrahydrofuran and dioxane; methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, Chain carbonates typified by tilpropyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate, methyl trifluoroethyl carbonate; nitriles typified by acetonitrile and propionitrile; typified by dimethyl ether A chain carboxylic acid ester represented by methyl propionate; a chain ether carbonate compound represented by dimethoxyethane. These are used singly or in combination of two or more.

  In particular, when the electrolytic solution is used for a lithium ion secondary battery or a lithium ion capacitor, the nonaqueous solvent is composed of a cyclic aprotic polar solvent and a nitrile solvent from the viewpoint of increasing the ionization degree of the lithium salt that contributes to charging and discharging. It is preferable to include one or more solvents selected from the group, and it is more preferable to include one or more cyclic carbonates typified by ethylene carbonate and propylene carbonate. Cyclic aprotic polar solvents and nitrile solvents have a high dielectric constant and tend to act effectively to aid ionization of the lithium salt and increase gelation ability.

An ionic liquid can also be used as the nonaqueous solvent. An ionic liquid is a liquid composed of ions obtained by combining an organic cation and an anion.
Examples of organic cations include, but are not limited to, imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations, tetraalkylammonium ions, alkylpyridinium ions, dialkylpyrrolidinium ions, and dialkylpiperidinium ions. It is done.

The anions that serve as counter ions of these organic cations are not limited to the following. For example, PF ₆ anions, PF ₃ (C ₂ F ₅ ) ₃ anions, PF ₃ (CF ₃ ) ₃ anions, BF ₄ anions, BF ₂ (CF ₃ ) ₂ anion, BF ₃ (CF ₃ ) anion, bisoxalate borate anion, Tf (trifluoromethanesulfonyl) anion, Nf (nonafluorobutanesulfonyl) anion, bis (fluorosulfonyl) imide anion, bis ( A trifluoromethanesulfonyl) imide anion, a bis (pentafluoroethanesulfonyl) imide anion, or a dicyanoamine anion can be used.

<Electrolyte>
(Ii) The electrolyte is not particularly limited as long as it is used as a normal nonaqueous electrolyte in the electrolytic solution, and any electrolyte may be used. The “gel electrolyte” described later indicates a gel electrolyte, and is not the same as the “electrolyte” in this section. When the electrolytic solution is used in a lithium ion secondary battery and a lithium ion capacitor, a lithium salt is used as an electrolyte. Specific examples of the lithium salt include, but are not limited to, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{2k + 1} [k is an integer of 1 to 8], LiN (SO ₂ C _k F _{2k + 1} ) ₂ [k is an integer of 1 to 8], LiPF _n (C _k F _{2k + 1} ) _6-n [n is an integer of 1 to 5, k is an integer of 1 to 8], LiBF _n ((C _k F _{2k + 1} ) _4-n [n is an integer of 1 to 3, k is an integer of 1 to 8], lithium bis (oxalate) borate represented by LiB (C ₂ O ₄ ) ₂ , LiBF ₂ ( C ₂ O ₄₎ lithium difluoro represented by (oxalate) _borate, lithium tetrafluoro (oxalato) phosphate represented by _{LiPF 4 (C 2 O 4)} , LiPO 2 F 2, L ₂ PO ₃ F, and the like.

Further, lithium salts represented by the following general formulas (2a), (2b), and (2c) can also be used.
LiC (SO ₂ R ¹¹ ) (SO ₂ R ¹² ) (SO ₂ R ¹³ ) (2a)
LiN (SO ₂ OR ¹⁴ ) (SO ₂ OR ¹⁵ ) (2b)
LiN (SO ₂ R ¹⁶ ) (SO ₂ OR ¹⁷ ) (2c)
Here, in the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ may be the same as or different from each other, and a perfluoroalkyl group having 1 to 8 carbon atoms. Indicates.

These lithium salts are used singly or in combination of two or more. Among these lithium salts, in particular, LiPF ₆ , LiBF ₄ , LiN (SO ₂ C _k F _{2k + 1} ) ₂ [k is an integer of 1 to 8] from the viewpoint of enhancing gelation ability in addition to battery characteristics and stability. LiB (C ₂ O ₄ ) ₂ is preferred, and LiPF ₆ and LiBF ₄ are most preferred.
The lithium salt is preferably contained in the electrolytic solution at a concentration of 0.1 to 3 mol / liter, more preferably 0.5 to 2 mol / liter.

  (Iii) The perfluoro group-containing compound acts, for example, as a gelling agent or as a safety improving additive such as a flame retardant, and is represented by the above general formula (1), either alone or in combination. Two or more types are used in combination.

The compound represented by the above general formula (1) (hereinafter referred to as “compound (1)”) has two perfluoroalkyl (oligomethylene) groups and an aromatic ring or alicyclic ring (excluding carbocyclic aromatic rings). It can also be referred to as a compound having In the general formula (1), X and X ′ each independently represent an S atom, O atom, SO group or SO ₂ group, and X and X ′ are groups different from each other. A compound having an S atom or SO group is excellent in handleability and easy to synthesize. A compound having an O atom or a SO ₂ group is excellent in both gelling performance and battery characteristics. In addition, X and X ′ are different from each other in terms of gelling ability (the amount of gelling agent necessary for gelling the electrolytic solution, the heating temperature necessary for dissolving the gelling agent in the electrolytic solution), battery characteristics (long-term It is advantageous to simultaneously achieve various performances such as charge / discharge cycle characteristics, storage characteristics, temperature characteristics) and safety (heat runaway suppression, overcharge runaway suppression).

  Ar and Ar 'each independently represents a substituted or unsubstituted divalent aromatic group or alicyclic group having 5 to 20 ring atoms, and Ar and Ar' are different from each other. The divalent aromatic group is a cyclic divalent group exhibiting so-called “aromaticity”. The divalent aromatic group (aromatic hydrocarbon group) may be a monocyclic group or a heterocyclic group. A divalent alicyclic group (alicyclic hydrocarbon group) has a single bond between carbons and may or may not have a non-conjugated multiple bond between carbons. It is a divalent group. These divalent aromatic hydrocarbon groups or alicyclic hydrocarbon groups may be substituted with a substituent or may be unsubstituted. The substituent is selected from the viewpoint of easily allowing the introduction of a perfluoroalkyl (oligomethylene) thio group and a hydrocarbon oxy group, which will be described later, or optimizing the melting point and gelling ability of the gelling agent. The

  The monocyclic group has 6-30 ring-forming atoms, may be substituted with a substituent, or may be unsubstituted or unsubstituted. Specific examples thereof include, but are not limited to, divalent having a ring represented by a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, an anthranylene group, a phenanthrylene group, a pyrenylene group, a chrysenylene group, and a fluoranthenylene group. The group of is mentioned. Further, the monocyclic group may have two or more of the above-described divalent groups within the range of 5 to 20 ring-forming atoms. Here, two or more divalent groups may be the same as or different from each other. When using a monocyclic group, from the viewpoint of easy synthesis and ease of gelation, any of a substituted or unsubstituted phenylene group, biphenylene group, terphenylene group, naphthylene group, or anthranylene group may be used. Preferably, any of a substituted or unsubstituted phenylene group, biphenylene group, and naphthylene group is used.

  The heterocyclic group has 5 to 20 ring-forming atoms, and is not limited to the following. For example, pyrrolene group, furylene group, thiophenylene group, triazolen group, oxadiazolene group, pyridylene group, pyrimidylene And a divalent group having a ring represented by the group. Further, the heterocyclic group may have two or more of the above-described divalent groups within the range of 5 to 20 ring-forming atoms. Here, two or more divalent groups may be the same as or different from each other.

  Furthermore, Ar and Ar ′ may be a group having both the above monocyclic group and heterocyclic group within the range of 5 to 20 ring-forming atoms.

  The alicyclic group has 5 to 20 ring-forming atoms and is not limited to the following, but examples thereof include a divalent group having a ring represented by a cyclopentane group, a cyclohexane group, and a cyclooctane group. .

Among these, a substituted or unsubstituted phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, an anthranylene group, or a pyridylene group is preferable from the viewpoint of more effectively and reliably achieving the effects of the present embodiment, and a substituted or unsubstituted group. A phenylene group, a biphenylene group, and a naphthylene group are more preferable, and a substituted or unsubstituted phenylene group and a biphenylene group are more preferable. From the viewpoint of easy availability of raw materials and easy synthesis, a phenylene group is preferable, and a biphenylene group is preferable from the viewpoint of showing high gelling ability with a small amount of use.
Moreover, as said substituent, although not limited to the following, For example, the alkyl group represented by the methyl group and the ethyl group, and a halogen atom are mentioned.
The difference between Ar and Ar ′ is that the gelling ability (the amount of gelling agent necessary for gelling the electrolyte, the heating temperature necessary for dissolving the gelling agent in the electrolyte), battery characteristics (long-term charge / discharge) It is advantageous to achieve various performances such as cycle characteristics, storage characteristics, temperature characteristics) and safety (heat runaway suppression, overcharge runaway suppression) at the same time.

R and R ′ each represents a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms in the main chain. R and R ′ may be the same or different from each other. R and R ′ may be a divalent aliphatic hydrocarbon group, and may further have a monovalent aromatic hydrocarbon group such as a phenyl group as a substituent. When the divalent hydrocarbon group is a divalent aliphatic hydrocarbon group, it may be branched or unbranched (straight). When the divalent hydrocarbon group has a monovalent aromatic hydrocarbon group as a substituent, the aromatic hydrocarbon group may or may not have a substituent.
Examples of the unsubstituted divalent hydrocarbon group include, but are not limited to, branched or straight chain having 1 to 6 carbon atoms such as a methylene group, an ethylene group, a propylene group, an n-butylene group, and an isobutylene group. Alkylene groups, oxymethylene groups, oxyethylene groups, oxypropylene groups, oxydimethylene groups, oxydiethylene groups, oxydipropylene groups and other oxyalkylene groups, thiomethylene groups, thioethylene groups, thiopropylene groups, thiodimethylene groups, thiodiethylenes And thioalkylene groups such as a thiodipropylene group.
R and R ′ are each independently preferably a divalent hydrocarbon group having 2 to 6 carbon atoms, and more preferably a divalent hydrocarbon group having 2 to 4 carbon atoms. R and R ′ are each independently preferably an alkylene group, and more preferably an alkylene group having 2 to 4 carbon atoms.
When R and R ′ are in the above ranges, a compound (1) having a high gelation ability can be obtained through an easy synthesis route in which raw materials are easily available.
The compound (1) has a structure in which one of Ar and Ar ′ is a phenylene group, the other is a biphenylene group, and one of X and X ′ is an S atom and the other is an SO ₂ group. preferable. This is because such a structure can provide a high level of ease of synthesis, gelling ability, battery characteristics, and safety.

  Rf and Rf 'each represent a substituted or unsubstituted divalent perfluoroalkyl group having 2 to 18 carbon atoms in the main chain. Rf and Rf ′ may be the same or different from each other. The main chain has preferably 4 to 16 carbon atoms, more preferably 4 to 10 carbon atoms. By making the carbon number within the above range, the compound (1) is easy to synthesize, exhibits high gelling ability, and is excellent in handleability.

Z represents a substituted or unsubstituted divalent hydrocarbon group or oxyhydrocarbon group having 1 to 8 carbon atoms in the main chain. _{Specifically, -O (C n H 2n)} O -, - O (C p H 2q OC q H 2q) O- , and the like. From the viewpoint of improving the gelation ability and the viewpoint of ease of synthesis, —O (C _n H _2n ) O— is preferable.

  As described above, the compound (1) has perfluoroalkyl groups at both ends. Having a plurality of perfluoroalkyl groups is excellent in that the gelling ability is increased even if the perfluoroalkyl chain is relatively short. Since the perfluoroalkyl group becomes difficult to obtain as the alkyl chain in it becomes longer, the perfluoroalkyl group becomes a gel even if the alkyl chain of the perfluoroalkyl group is short, which is an advantage of the compound (1). . In addition, the compound (1) has a relatively simple structure and is excellent from the viewpoints of ease of synthesis and availability of synthetic raw materials.

  Although the manufacturing method of the compound (1) of this embodiment is not specifically limited, For example, it can synthesize | combine by the following scheme or the scheme according to it (synthesis | combination of a compound (2) and a compound (3)). In more detail, it can be synthesized by the method described in the examples.

(In the above formula, n, P, and Q are arbitrary integers.)

(In the above formula, n, P, and Q are arbitrary integers.)

  Compound (1) can gel the nonaqueous solvent in this embodiment by adding a small amount of about 20% or less. The compound (1) is added to a non-aqueous solvent, dissolved by heating, and the resulting solution is gelled by returning to room temperature. These compounds can be added in a small amount of, for example, 0.3 to 20% by mass, preferably about 0.4 to 15% by mass, with a high dielectric constant aprotic polar solvent suitable for an electrolyte, such as propylene carbonate. It is possible to gel a cyclic carbonate represented by butylene carbonate; a lactone represented by γ-butyrolactone and γ-valerolactone; a cyclic sulfone represented by sulfolane; a nitrile represented by acetonitrile.

  The perfluoro group-containing compound in the present embodiment is used alone or in combination of two or more of the above compound (1).

  The mixing ratio of the perfluoro group-containing compound and the non-aqueous solvent is arbitrary, but from the viewpoint of improving the gelling ability and the handleability, the perfluoro group-containing compound: non-aqueous solvent is 0. It is preferable that it is 1: 99.9-20: 80, and it is more preferable that it is 0.5: 99.5-15: 85. The more the perfluoro group-containing compound, the higher the gel-sol phase transition point and the stronger the gel. The less the perfluoro group-containing compound, the lower the viscosity and the easier to handle the gel.

  The mixing ratio of the nonaqueous solvent, the electrolyte and the perfluoro group-containing compound can be selected according to the purpose, but the electrolyte is preferably 0.1 to 3 mol / liter, more preferably 0.5 to The gelling agent is a mass-based perfluoro group-containing compound: a non-aqueous solvent, preferably 0.1: 99.9 to 20:80, more preferably 0.3, with respect to the mixed solution mixed at 2 mol / liter. : It is preferable to add 99.7-10: 90. By producing an electrolytic solution with such a composition, all of battery characteristics, handleability and safety can be improved.

In addition, it does not specifically limit as a manufacturing method of the electrolyte solution of this embodiment, It can manufacture by mixing suitably the nonaqueous solvent mentioned above, electrolyte, and a perfluoro group containing compound. That is, various orders can be selected as the mixing order of the nonaqueous solvent, the electrolyte, and the compound (1). For example, a method of preparing an electrolytic solution in which a predetermined amount of electrolyte is dissolved in a nonaqueous solvent and then introducing the compound (1) into the electrolytic solution can be selected. The electrolytic solution into which the compound (1) is introduced can be prepared by raising the temperature to 70 to 150 ° C. to make a uniform solution and then lowering the temperature to room temperature.
Alternatively, the non-aqueous solvent and the compound (1) are mixed, the temperature is raised to 70 to 150 ° C. to dissolve the compound (1), the temperature is lowered, and then the electrolyte is dissolved to prepare the electrolytic solution. Good.
Furthermore, it is also possible to prepare an electrolytic solution by mixing all the compounds at the same time.
In addition, in the range which does not inhibit the desired effect of this embodiment, the electrolyte solution of this embodiment may contain gelling agents other than compound (1) in addition to compound (1) as a gelling agent. Good.

  The electrolytic solution of the present embodiment is preferably a gelled gel electrolyte from the viewpoint of achieving both battery characteristics and safety. Here, the gel electrolyte is different from the “electrolyte” of the present embodiment described above, and indicates a gel electrolyte of an originally liquid electrolyte solution by the action of the perfluoro group-containing compound in the present embodiment. Whether or not it belongs to the gel electrolyte can be determined, for example, by performing “evaluation of gelling ability of the electrolytic solution” described in Examples described later.

<Positive electrode>
A positive electrode will not be specifically limited if it acts as a positive electrode of a lithium ion secondary battery, A well-known thing may be used. The positive electrode preferably contains one or more materials selected from the group consisting of materials capable of inserting and extracting lithium ions as the positive electrode active material. Examples of such materials include, but are not limited to, composite oxides represented by the following general formulas (6a) and (6b), metal chalcogenides having a tunnel structure and a layered structure, and metal oxides. .
Li _x MO ₂ (6a)
Li _y M ₂ O ₄ (6b)
Here, in the formula, M represents one or more metals selected from transition metals, x represents a number from 0 to 1, and y represents a number from 0 to 2.

More specifically, although not limited to the following, for example, lithium cobalt oxide typified by LiCoO ₂ ; lithium manganese oxide typified by LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₄ ; LiNiO ₂ Li _z MO ₂ (M represents two or more elements selected from the group consisting of Ni, Mn, Co, Al, and Mg, and z is more than 0.9 and less than 1.2. A lithium-containing composite metal oxide represented by LiFePO ₄ ; and an iron phosphate olivine represented by LiFePO ₄ . Also, as the positive electrode active material include, but are not limited to, for _{example, S,} is represented by _{MnO 2, FeO 2, FeS 2} , V 2 O 5, V 6 O 13, TiO 2, TiS 2, MoS 2 and NbSe ₂ Examples thereof include oxides of metals other than lithium. Furthermore, conductive polymers represented by polyaniline, polythiophene, polyacetylene, and polypyrrole are also exemplified as the positive electrode active material.

Further, it is preferable to use a lithium-containing compound as the positive electrode active material because a high voltage and a high energy density tend to be obtained. Such a lithium-containing compound is not limited to the following as long as it contains lithium, and is, for example, a composite oxide containing lithium and a transition metal element; a phosphate compound containing lithium and a transition metal element And a metal silicate compound containing lithium and a transition metal element (for example, Li _t M _u SiO ₄ , M is as defined in the above formula (6a), t is a number from 0 to 1, u is a number from 0 to 2. Etc.). From the viewpoint of obtaining a higher voltage, lithium, cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), vanadium ( V) and composite oxides containing at least one transition metal element selected from the group consisting of titanium (Ti) and phosphate compounds are preferred.

More specifically, the lithium-containing compound is preferably a metal oxide having lithium, a metal chalcogenide having lithium, and a metal phosphate compound having lithium. For example, the lithium-containing compounds are represented by the following general formulas (7a) and (7b). The compound which is made is mentioned.
^{_{Li v M I O 2 (7a}} )
Li _w M ^II PO ₄ (7b)
Here, in the formula, M ^I and M ^II each represent one or more transition metal elements, and the values of v and w vary depending on the charge / discharge state of the battery, but usually v is 0.05 to 1.10, w Indicates a number from 0.05 to 1.10.

  The compound represented by the general formula (7a) generally has a layered structure, and the compound represented by the general formula (7b) generally has an olivine structure. In these compounds, for the purpose of stabilizing the structure, a part of the transition metal element is substituted with Al, Mg, other transition metal elements or included in the crystal grain boundary, a part of the oxygen atom And those substituted with a fluorine atom or the like. Furthermore, what coat | covered the other positive electrode active material to at least one part of the positive electrode active material surface is mentioned.

  A positive electrode active material is used individually by 1 type or in combination of 2 or more types.

  The number average particle diameter (primary particle diameter) of the positive electrode active material is preferably 0.05 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the positive electrode active material can be measured by a wet particle size measuring device (for example, a laser diffraction / scattering particle size distribution meter, a dynamic light scattering particle size distribution meter). Alternatively, 100 particles observed with a transmission electron microscope are randomly extracted and analyzed with image analysis software (for example, image analysis software manufactured by Asahi Kasei Engineering Co., Ltd., trade name “A Image-kun”). It can also be obtained by calculating an average. In this case, when the number average particle diameter differs between measurement methods for the same sample, a calibration curve created for the standard sample may be used.

Although a positive electrode is not limited to the following, for example, it is obtained as follows. That is, first, a positive electrode mixture-containing paste is prepared by dispersing, in a solvent, a positive electrode mixture obtained by adding a conductive additive, a binder, or the like to the positive electrode active material as necessary. Next, this positive electrode mixture-containing paste is applied to a positive electrode current collector and dried to form a positive electrode mixture layer, which is pressurized as necessary to adjust the thickness, thereby producing a positive electrode.
Here, the solid content concentration in the positive electrode mixture-containing paste is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass.
The positive electrode current collector is not limited to the following, but is constituted by, for example, a metal foil such as an aluminum foil or a stainless steel foil.

<Negative electrode>
A negative electrode will not be specifically limited if it acts as a negative electrode of a lithium ion secondary battery, A well-known thing may be used. The negative electrode preferably contains at least one material selected from the group consisting of a material capable of inserting and extracting lithium ions as a negative electrode active material and metallic lithium. In addition to metallic lithium, such materials include, but are not limited to, for example, amorphous carbon (hard carbon), artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, organic polymer compounds Examples thereof include carbon materials typified by fired bodies, mesocarbon microbeads, carbon fibers, activated carbon, graphite, carbon colloid, carbon black and the like. Among these, the coke is not limited to the following, and examples thereof include pitch coke, needle coke, and petroleum coke. Further, the fired body of the organic polymer compound is obtained by firing and polymerizing a polymer material such as a phenol resin or a furan resin at an appropriate temperature. In the present embodiment, a battery employing metallic lithium as the negative electrode active material is also included in the lithium ion secondary battery. The negative electrode active material in the present embodiment preferably contains one or more materials selected from the group consisting of metallic lithium, carbon materials, materials containing elements capable of forming an alloy with lithium, and lithium-containing compounds.

  Further, examples of the material capable of inserting and extracting lithium ions include a material containing an element capable of forming an alloy with lithium. This material may be a single metal or semi-metal, an alloy or a compound, and may have at least a part of one or more of these phases. .

  In the present specification, the “alloy” includes an alloy having one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. In addition, the alloy may have a nonmetallic element as long as the alloy has metallic properties as a whole. In the alloy structure, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of these coexist.

  Examples of such metal elements and metalloid elements include, but are not limited to, titanium (Ti), tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), and zinc (Zn). ), Antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr), yttrium (Y), and the like. .

  Among these, metal elements and metalloid elements of Group 4 or 14 in the long-period periodic table are preferable, and titanium, silicon, and tin are particularly preferable.

  Examples of tin alloys include, but are not limited to, for example, silicon, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, Examples thereof include those having one or more elements selected from the group consisting of antimony and chromium.

  Examples of the alloy of silicon include, but are not limited to, for example, tin, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, Examples thereof include those having one or more elements selected from the group consisting of antimony and chromium.

  The titanium compound, tin compound, and silicon compound are not limited to the following, but include, for example, those having oxygen (O) or carbon (C). In addition to titanium, tin, or silicon, the second compound described above is used. It may have a constituent element.

  A negative electrode active material is used individually by 1 type or in combination of 2 or more types.

  The number average particle diameter (primary particle diameter) of the negative electrode active material is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the negative electrode active material is measured in the same manner as the number average particle size of the positive electrode active material.

Although a negative electrode is not limited to the following, for example, it is obtained as follows. That is, first, a negative electrode mixture-containing paste is prepared by dispersing, in a solvent, a negative electrode mixture prepared by adding a conductive additive or a binder to the negative electrode active material, if necessary. Next, the negative electrode mixture-containing paste is applied to a negative electrode current collector and dried to form a negative electrode mixture layer, which is pressurized as necessary to adjust the thickness, thereby producing a negative electrode.
Here, the solid content concentration in the negative electrode mixture-containing paste is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass.
Although a negative electrode electrical power collector is not limited to the following, For example, metal foils, such as copper foil, nickel foil, aluminum foil, or stainless steel foil, etc. are comprised.

  In the production of the positive electrode and the negative electrode, the conductive aid used as necessary is not limited to the following, and examples thereof include carbon black typified by graphite, acetylene black, and ketjen black, carbon fiber, and the like. The number average particle size (primary particle size) of the conductive assistant is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm, and is measured in the same manner as the number average particle size of the positive electrode active material. Examples of the binder include, but are not limited to, PVDF, PTFE, polyacrylic acid, styrene butadiene rubber, and fluorine rubber.

<Separator>
In the lithium ion secondary battery of the present embodiment, a separator can be provided between the positive electrode and the negative electrode from the viewpoint of providing safety such as prevention of short circuit between the positive and negative electrodes and shutdown. The separator is preferably an insulating thin film having high ion permeability and excellent mechanical strength.

  Although the material of the separator used for this embodiment is not limited to the following, For example, a ceramic, glass, resin, a cellulose etc. are mentioned. The resin may be a synthetic resin or a natural resin (natural polymer), and may be an organic resin or an inorganic resin. This is preferable because it tends to be excellent. The organic resin is not limited to the following, but from the viewpoint of ensuring shutdown performance at the time of abnormality, facilitating film formation, and improving the degree of freedom in molecular design (affinity with other members), for example, polyolefin, Examples thereof include heat-resistant resins such as polyester, polyamide, liquid crystal polyester, and aramid. From the viewpoint of high heat resistance, ceramics and glass are preferable, and from the viewpoint of handleability and heat resistance, polyester, polyamide, liquid crystal polyester, aramid, and cellulose are preferable. Further, from the viewpoint of cost and processability, polyolefin is preferable. Among these materials, when a resin is employed, a resin that is a homopolymer may be used, a copolymer resin may be used, or a mixture of a plurality of types of resins and an alloy may be used.

  Further, the separator may be a laminated body in which films made of a plurality of materials are laminated. When the separator is a laminate, the material of each layer may be the same or different. In the case of manufacturing a separator of a laminated body, it may be manufactured by sequentially stacking a certain layer on another layer, that is, by sequentially multilayering, and a plurality of separate films may be bonded together. Thus, a laminate may be produced, or each layer may be formed simultaneously and laminated in-line.

  Although the form of the separator used in this embodiment is not limited to the following, for example, a synthetic resin microporous film manufactured by forming a synthetic resin film, a fiber obtained by spinning a synthetic resin or a natural resin, a glass fiber, or a ceramic fiber Examples thereof include processed woven fabrics, non-woven fabrics, knitted fabrics, papermaking, and films prepared by arranging fine particles of synthetic resin and glass.

  The separator according to the present embodiment is made of a component other than the above, for example, an organic filler, an inorganic filler, an organic particle, or an inorganic particle on the surface and / or inside of the separator from the viewpoints of film reinforcement, charge / discharge assist, heat resistance improvement, and the like. May be included.

<Production method of battery>
The lithium ion secondary battery of this embodiment is produced by a known method using the above-described electrolyte solution, positive electrode, negative electrode, and optionally a separator. For example, a plurality of positive electrodes in which a positive electrode and a negative electrode are wound in a laminated state with a separator interposed therebetween to be formed into a laminate having a wound structure, or they are alternately laminated by bending or laminating a plurality of layers. Or a laminate in which a separator is interposed between the electrode and the negative electrode. Next, the laminated body is accommodated in a battery case (exterior), the electrolytic solution according to the present embodiment is injected into the case, and the laminated body is immersed in the electrolytic solution and sealed. The lithium ion secondary battery can be manufactured. Alternatively, an electrolyte membrane containing a gelled electrolyte solution is prepared in advance, and a positive electrode, a negative electrode, an electrolyte membrane, and optionally a separator are formed by bending or stacking as described above, and then placed in the battery case. A lithium ion secondary battery can also be produced by housing. The shape of the lithium ion secondary battery of the present embodiment is not particularly limited, and for example, a cylindrical shape, an elliptical shape, a rectangular tube shape, a button shape, a coin shape, a flat shape, a laminate shape, and the like are suitably employed.

  The electrolytic solution (electrolytic solution for electrochemical device) and the lithium ion secondary battery of the present embodiment have high safety (for example, flame retardancy and liquid retention) and high battery characteristics (for example, long-term durability and high rate). The lithium ion secondary battery has high battery characteristics (for example, charge / discharge characteristics, low temperature operability, high temperature durability, etc.) and high safety (suppression of lithium dendrite). Is also realized. For example, even when the electrolyte solution of the present embodiment includes four or more kinds of the nonaqueous solvent and the electrolyte, the low molecular weight perfluoro group-containing compound added in the present embodiment is a property of the nonaqueous solvent and the electrolyte. Will not be damaged. Therefore, the electrolytic solution and the lithium ion secondary battery of the present embodiment can exhibit high safety without deteriorating high battery characteristics derived from the nonaqueous solvent and the electrolyte. Further, since the electrolyte solution of the present embodiment contains a low-molecular weight perfluoro group-containing compound, it is possible to prevent leakage of the electrolyte solution to the outside of the battery, as well as the lithium ion secondary battery of the present embodiment. In addition, the risk of inconvenience and combustion due to lithium dendrite can be further reduced.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said embodiment. The present invention can be variously modified without departing from the gist thereof.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Various characteristics and safety of the electrolytic solution and the lithium ion secondary battery were measured and evaluated as follows.

(I) Evaluation of gelling ability of electrolyte solution By preparing an electrolyte solution in a glass sample bottle and leaving it at 25 ° C for 2 hours, the sample bottle is turned upside down, and the fluidity at that time is confirmed visually. The gelation ability was evaluated. The evaluation criteria are as follows.
○: It does not flow.
X: Flows.

(Ii) Evaluation of stability of gel property of electrolytic solution The electrolytic solution prepared in “(i) Evaluation of gelling ability of electrolytic solution” is allowed to stand for 3 days at 25 ° C., and visually checked for gel property retention. Confirmed with. The evaluation result criteria are as follows.
○: The gel property of the same level as that immediately after preparation is maintained.
(Triangle | delta): It is the gel which a part liquid exuded.
X: The gel property is lost and the liquid is uniform. Alternatively, the liquid and the solid are separated.

(Iii) Electrical conductivity measurement of electrolyte solution An electrolyte solution was prepared in a glass sample bottle and connected to an electrical conductivity meter “CM-30R” (trade name) manufactured by Toa DK Corporation. The cell for electrical conductivity measurement “CT-57101B” (trade name) was inserted into a sample bottle containing an electrolytic solution and heated to 75 ° C. Thereafter, the temperature of the sample bottle was lowered to 30 ° C. while the electric conductivity measurement cell was inserted, and the electric conductivity of the electrolytic solution at 30 ° C. was measured.

(Iv) Discharge capacity measurement The discharge capacity at a specific discharge current was measured to evaluate the discharge characteristics of the lithium ion secondary battery. As a lithium ion secondary battery for measurement, a small battery with 1C = 6 mA was prepared and used. The measurement was performed using a charge / discharge device ACD-01 (trade name) manufactured by Asuka Electronics Co., Ltd. and a thermostat PLM-63S (trade name) manufactured by Futaba Kagaku Co., Ltd. After charging at a constant current of 6 mA and reaching 4.2 V, charging was performed at a constant voltage of 4.2 V for a total of 3 hours. Then, the discharge capacity when discharging to 3.0 V with a constant current was measured. The discharge capacity was measured by setting the discharge current to 6 mA and 18 mA. The battery ambient temperature at this time was set to 25 ° C.

(V) Safety test (combustion test)
An electrolyte solution combustion test was performed to evaluate the electrolyte and battery safety. 1 mL of the electrolyte solution heated to 110 ° C. was absorbed onto a 13 mm × 125 mm × 2 mm glass filter paper, and then the glass filter paper was cooled to 25 ° C. to prepare a sample. Set the sample to “mcm-2” (trade name), a multi-calorie meter made by Toyo Seiki Co., Ltd., and conduct a horizontal combustion test of UL94HB. The time required for ignition (ignition time), from ignition The time required for the flame to propagate to the edge of the filter paper (elapsed time) and the time from ignition to extinguishing (burning time) were measured.

Example 1
(1) Preparation of electrolyte solution Ethylene carbonate and methyl ethyl carbonate were mixed at a mass ratio of 1: 2, and the mixture was gelled by adding LiPF ₆ to 1 mol / L. No electrolyte solution (A) was prepared. A compound represented by the following formula (4) is added as a gelling agent to the electrolytic solution (A) so as to be 7% by mass with respect to the total amount of the electrolytic solution, and heated to 105 ° C. to be uniform. Then, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (a). The electrolyte solution (a) was a gel electrolyte that was sufficiently gelled.

(Example 2)
A non-gelled electrolyte solution (B) was prepared by adding LiN (SO ₂ CF ₂ ) ₂ to propylene carbonate at 1 mol / L. To the electrolyte solution (B), the compound represented by the above formula (4) is added as a gelling agent so as to be 2% by mass with respect to the total amount of the electrolyte solution, and heated to 75 ° C. uniformly After mixing, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (b).

(Example 3)
Ethylene carbonate, propylene carbonate, and γ-butyrolactone are mixed at a mass ratio of 1: 1: 2, and LiBF ₄ is added to the mixture so as to be 1.5 mol / L to be gelled. An electrolytic solution (C) not formed was prepared. The compound represented by the above formula (4) is added to the electrolyte solution (C) as a gelling agent so as to be 7% by mass with respect to the total amount of the electrolyte solution, and heated to 105 ° C. uniformly. After mixing, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (c).

Example 4
A compound represented by the following formula (5) is added as a gelling agent to the non-gelled electrolyte solution (A) so as to be 7% by mass with respect to the total amount of the electrolyte solution. After heating and mixing uniformly, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (d). The electrolytic solution (d) was a gel electrolyte that was sufficiently gelled.

(Example 5)
A compound represented by the above formula (5) is added as a gelling agent to the non-gelled electrolyte solution (C) so as to be 2% by mass with respect to the total amount of the electrolyte solution, and heated to 105 ° C. After uniformly mixing, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (e).

(Comparative Example 1)
An electrolytic solution (f) was obtained in the same manner as in the preparation of the electrolytic solution (a) in Example 1 except that the gelling agent was not added.

(Comparative Example 2)
An electrolytic solution (g) was obtained in the same manner as in the preparation of the electrolytic solution (b) in Example 2 except that the gelling agent was not added.

(Comparative Example 3)
An electrolytic solution (h) was obtained in the same manner as in the preparation of the electrolytic solution (c) in Example 3 except that no gelling agent was added.

(Comparative Example 4)
10% by mass of a polyurethane composed of a diol compound having a molecular weight of 1000 and an OH value of 110 mgKOH / g and an isocyanate is added to the electrolyte solution (C), and the polyurethane solution is made to absorb the electrolyte solution (C). i) (hereinafter referred to as electrolyte solution (g)) was obtained. The resulting polyurethane gel electrolyte (i) had a thickness of 30 μm.

(Comparative Example 5)
Ethylene carbonate and methyl ethyl carbonate were mixed at a mass ratio of 1: 2, thereby preparing a non-gelled mixed solvent (D). The compound represented by the above formula (4) is added to the mixed solvent (D) as a gelling agent so as to be 10% by mass with respect to the total amount of the electrolytic solution, and heated to 105 ° C. uniformly. After mixing, the temperature was lowered to 25 ° C. to obtain an electrolytic solution (j). The electrolyte solution (j) was a gel electrolyte that was sufficiently gelled.

(Example 6)
(2) Production of positive electrode Lithium cobalt acid (LiCoO ₂ ) having a number average particle diameter of 5 μm as a positive electrode active material, graphite carbon powder having a number average particle diameter of 3 μm as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder. Mixed at a mass ratio of 85: 10: 5. N-methyl-2-pyrrolidone was added to the obtained mixture so as to have a solid content of 60% by mass and further mixed to prepare a slurry solution. This slurry-like solution was applied to one side of an aluminum foil having a thickness of 20 μm, and the solvent was dried and removed, followed by rolling with a roll press. The rolled product was punched into a disk shape having a diameter of 16 mm to obtain a positive electrode.

(3) Production of negative electrode Mesocarbon microbeads having a number average particle diameter of 5 μm as a negative electrode active material and diene rubber as a binder (glass transition temperature: −5 ° C., number average particle diameter upon drying: 120 nm, dispersion medium: water And a solid content concentration of 40 mass%) were mixed so that the solid content concentration of the negative electrode active material was 60 mass% while adjusting the viscosity with carboxymethylcellulose to prepare a slurry-like solution. The slurry solution was applied to one side of a 10 μm thick copper foil, and the solvent was removed by drying, followed by rolling with a roll press. The rolled product was punched into a disk shape having a diameter of 16 mm to obtain a negative electrode.

(4) Battery assembly A laminate in which the positive electrode and the negative electrode produced as described above are superposed on both sides of a separator made of polyethylene (film thickness: 25 μm, porosity: 50%, pore diameter: 0.1 μm to 1 μm) It was inserted into a disk type battery case. Next, 0.5 mL of the electrolyte solution (a) heated to 110 ° C. was injected into the battery case, and the laminate was immersed in the electrolyte solution (a). Then, the battery case was sealed and a lithium ion secondary battery (small size) Battery). The lithium ion secondary battery was held at 110 ° C. for 1 hour and then cooled to 25 ° C. to obtain a battery (a).

(Example 7)
A battery (d) was obtained in the same manner as in Example 6 except that the electrolytic solution (d) was used instead of the electrolytic solution (a).

(Comparative Example 6)
A battery (f) was obtained in the same manner as in Example 4 except that the electrolytic solution (f) was used instead of the electrolytic solution (a).

(Comparative Example 7)
A laminate in which a positive electrode and a negative electrode produced in the same manner as in Example 6 were superimposed on both sides of the electrolyte solution (i) was inserted into a SUS disk-type battery case. Next, without immersing the laminate in the electrolyte, the battery case was sealed to produce a lithium ion secondary battery. This lithium ion secondary battery was held at 70 ° C. for 1 hour, and then cooled to 25 ° C. to obtain battery (i).

  The compounds represented by the chemical formulas (4) to (5) were synthesized as follows.

(Synthesis of Compound B)
4-Bromoanisole (Compound A, 10.07 g, 53.84 mmol), wrought magnesium (1.86 g, 76.51 mmol) and tetrahydrofuran (dehydrated) 50 mL were placed in a 200 mL two-necked flask under a nitrogen atmosphere at room temperature. The mixture was stirred until a gray solution was obtained. Next, after cooling to −78 ° C., trimethyl borate (6.32 g, 60.82 mmol) and 50 mL of tetrahydrofuran (dehydrated) were added and stirred for 2 hours. The mixture was then returned to room temperature and stirred for another 2 hours. After the stirring, 50 mL of 1N dilute hydrochloric acid was added in an ice-cooled atmosphere and stirred for 1 hour. After the stirring, the contents of the two-necked flask were transferred to a separatory funnel by allowing to stand until reaching room temperature. Ethyl acetate, water and saturated brine were added to the separatory funnel to separate the organic layer and the aqueous layer. Anhydrous magnesium sulfate was added to the organic layer obtained by repeating this liquid separation operation three times, and left for 1 hour. Thereafter, the organic layer was filtered, and the obtained filtrate was concentrated with an evaporator to obtain Compound B. Compound B was white crystals, the melting point was 205 to 206 ° C., the yield was 77%, and the yield was 6.25 g.

The structure of Compound B was confirmed as follows.
IR (KBr disc) measurement results:
[nu] = 3358 (O-H), 1601, 1580 (C = C), 1250 (> O) cm < ^-1 >.
¹ HNMR (500 MHz, DMSO-d ₆ ) measurement results:
δ = 3.76 (3H, s), 6.88 (2H, d, J = 8.5 Hz), 7.73 (2H, d, J = 8.5 Hz), 7.85 (2H, s) ppm

(Synthesis of Compound D)
4-Bromobenzenethiol (compound C, 11.96 g, 63.29 mmol), 2- (perfluorohexyl) ethyl iodide (30.02 g, 63.33 mmol), potassium carbonate (13.29 g, 96.16 mmol) and acetone 100 mL was placed in a 200 mL eggplant flask and refluxed at 60 ° C. overnight. After the reflux, the contents of the eggplant flask were allowed to stand until it reached room temperature, and transferred to a separatory funnel. Ether, water and saturated brine were added to the separatory funnel to separate the organic layer and the aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the organic layer was filtered, and the obtained filtrate was concentrated with an evaporator to obtain a solid. The solid was recrystallized from ethanol to obtain Compound D. Compound D was a white powder, the melting point was 39-41 ° C., the yield was 96%, and the yield was 32.41 g.

In addition, the structure of the compound D was confirmed as follows.
IR (KBr disc) measurement results:
ν = 1580, 1477 (C = C), 1248-1140 (C−F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.33-2.43 (2H, m), 3.10 (2H, m), 7.23 (2H, d, J = 8.5 Hz), 7.46 (2H, d, J = 8) .5Hz) ppm

(Synthesis of Compound E)
Compound D (1.93 g, 3.61 mmol), Compound B (0.65 g, 4.27 mmol), Sodium carbonate (0.75 g, 7.11 mmol), Palladium (II) acetate (0.01 g, 1.2 mol%) ), Triphenylphosphine (0.03 g, 3.2 mol%), 10 mL of water and 20 mL of 1,4-dioxane were placed in a 100 mL eggplant flask and refluxed at 100 ° C. for 12 hours under a nitrogen atmosphere. After the reflux, the mixture was allowed to stand until it reached room temperature, and neutralized by adding 30 mL of 1N dilute hydrochloric acid in an air atmosphere. Thereafter, a solid was obtained by suction filtration. The solid was dissolved in ethyl acetate and filtered with suction. Thereafter, the filtrate was concentrated with an evaporator to obtain a solid. The solid was purified by a silica gel column to obtain compound E. Compound E was a white powder, the melting point was 129 to 131 ° C., the yield was 93%, and the yield was 1.85 g.

The structure of Compound E was confirmed as follows.
IR (KBr disc) measurement results:
ν = 1601, 1580 (C = C), 1250 (> O), 1248-1140 (C−F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.33-2.48 (2H, m), 3.14 (2H, m), 3.85 (3H, s), 6.98 (2H, d, J = 9.2 Hz), 7. 41 (2H, d, J = 8.5 Hz), 7.52 (2H, d, J = 9.2 Hz), 7.52 (2H, d, J = 8.5 Hz) ppm

(Synthesis of Compound F)
Compound E (1.00 g, 1.78 mmol), boron tribromide (1.20 g, 4.79 mmol) and 50 mL of dichloromethane were placed in a 200 mL eggplant flask, stirred in an ice bath for 2 hours, and returned to room temperature. Stir for another 12 hours. Then, after adding water and stirring in an ice bath for 1 hour, the contents were transferred to a separatory funnel. Ether was added to the separatory funnel to separate an organic layer and an aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by fold filtration of the organic layer was concentrated with an evaporator to obtain Compound F. Compound F was a white powder, the melting point was 171 to 172 ° C., the yield was 89%, and the yield was 0.87 g.

The structure of Compound F was confirmed as follows.
IR (KBr disc) measurement results:
ν = 3445 (O—H), 1609, 1489 (C═C), 1234-1188 (C—F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.37-2.48 (2H, m), 3.14 (2H, m), 4.92 (1H, s), 6.91 (2H, d, J = 8.5 Hz), 7. 41 (2H, d, J = 7.9 Hz), 7.47 (2H, d, J = 8.5 Hz), 7.51 (2H, d, J = 7.9 Hz) ppm

(Synthesis of Compound H)
4-mercaptophenol (compound G, 2.67 g, 2.11 mmol), 2- (perfluorohexyl) ethyl iodide (10.01 g, 2.11 mmol), potassium carbonate (3.59 g, 2.60 mmol) and acetone 100 mL Was placed in a 300 mL eggplant flask and refluxed at 60 ° C. overnight. After the reflux, the contents of the eggplant flask were allowed to stand until reaching room temperature, and the contents of the eggplant flask were transferred to a separatory funnel. Ether, water, saturated brine, and 1N dilute hydrochloric acid were added thereto to make it acidic, and the organic layer and the aqueous layer were separated. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by folding and filtering the organic layer was concentrated with an evaporator to obtain a solid. The solid was purified by a silica gel column to obtain compound H. Compound H was a white powder, the melting point was 69-71 ° C., the yield was 79%, and the yield was 7.85 g.

The structure of Compound H was confirmed as follows.
IR (KBr) measurement results:
ν = 3431 cm ⁻¹ (O—H), 1591, 1496 cm ⁻¹ (C═C), 1236-1141 cm ⁻¹ (C—F)
¹ HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.28-2.38 ppm (2H, m), 2.99 ppm (2H, m, J = 8.2 Hz), 5.00 ppm (1H, s), 6.82 ppm (2H, d, J = 8) .5 Hz), 7.34 ppm (2H, d, J = 8.5 Hz)

(Synthesis of Compound I)
Compound H (3.00 g, 6.35 mmol), 1,6-dibromohexane (4.65 g, 19.1 mmol), potassium carbonate (1.11 g, 8.03 mmol) and acetone 100 mL were placed in a 200 mL eggplant flask. Refluxed at 60 ° C. for 8 hours. After the reflux, the contents of the eggplant flask were allowed to stand until reaching room temperature, and the contents of the eggplant flask were transferred to a separatory funnel. Ether, water and saturated brine were added to the separatory funnel to separate the organic layer and the aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by filtering the organic layer was concentrated with an evaporator to obtain a liquid. Methanol was added to the liquid for reprecipitation. The precipitated solid was removed by suction filtration to obtain a filtrate. The filtrate was purified by distillation under reduced pressure to obtain Compound I. Compound I was a pale yellow viscous liquid or pale yellow solid, its melting point was 32-35 ° C., the yield was 67%, and the yield was 2.72 g.

The structure of Compound I was confirmed as follows.
IR (KRS-5) measurement results:
ν = 2936,2862 (> CH ₂ ), 1595, 1495 (C═C), 1246-1144 (C—F), 640-520 (C—Br) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 1.49-1.58 (6H, m), 1.80 (2H, quin, J = 6.4 Hz), 1.90 (2H, quin, J = 6.4 Hz), 2.28-2 .38 (2H, m), 3.30 (2H, m), 3.42 (2H, t, J = 6.7 Hz), 3.95 (2H, t, J = 6.7 Hz), 6.86 (2H, d, J = 8.5 Hz), 7.36 (2H, d, J = 8.5 Hz) ppm

(Synthesis of Compound J)
Compound H (5.00 g, 1.06 mmol), 1,6-dibromohexane (7.86 g, 3.22 mmol), potassium carbonate (2.00 g, 1.45 mmol) and 3-pentanone 100 mL were added to a 200 mL eggplant flask. The mixture was refluxed at 120 ° C. overnight. After the reflux, the mixture was allowed to stand until it reached room temperature, and the contents of the eggplant flask were transferred to a separatory funnel. Ether, water and saturated brine were added to the separatory funnel to separate the organic layer and the aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by folding and filtering the organic layer was concentrated with an evaporator to obtain a liquid. Methanol was added to the liquid for reprecipitation. The precipitated solid was removed by suction filtration to obtain a filtrate.

  The filtrate (3.40 g, 5.35 mmol), 35% hydrogen peroxide (1.10 g, 11.32 mmol) and 50 mL of acetic acid were placed in a 100 mL eggplant flask and refluxed at 100 ° C. overnight. After the reflux, the contents of the eggplant flask were allowed to stand until reaching room temperature, and the contents of the eggplant flask were transferred to a separatory funnel. Water and sodium bisulfite were added to the separatory funnel to obtain a white precipitate. The precipitate was removed by suction filtration and washed with water to obtain a solid. The solid was purified by a silica gel column and washed with petroleum ether to obtain compound J. Compound J was a white powder, the melting point was 64-66 ° C., the yield was 55%, and the yield was 1.98 g.

The structure of Compound J was confirmed as follows.
IR (KBr) measurement results:
ν = 2939,2868 cm ⁻¹ (—CH ₂ —), 1598, 1496 cm ⁻¹ (C═C), 1246-1178 cm ⁻¹ (C—F), 640-520 cm ⁻¹ (C—Br)
¹ HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 1.52-1.58 ppm (8H, m), 1.85 ppm (2H, quin, J = 6.4 Hz), 1.91 ppm (2H, quin, J = 6.4 Hz), 2.53-2 .63 ppm (2H, m), 3.28-3.31 ppm (2H, m), 3.43 ppm (2H, t, J = 6.7 Hz), 4.06 ppm (2H, t, J = 6.4 Hz) 7.05 ppm (2H, d, J = 8.5 Hz), 7.85 ppm (2H, d, J = 8.5 Hz)

(Synthesis of Compound (4))
Compound F (0.27 g, 0.50 mmol), Compound J (0.30 g, 0.45 mmol), potassium carbonate (0.12 g, 0.87 mmol) and 3-pentanone 50 mL were placed in a 100 mL eggplant flask and 120 ° C. At reflux overnight. After the reflux, the contents of the eggplant flask were allowed to stand until reaching room temperature, and the contents of the eggplant flask were transferred to a separatory funnel. Water was added to the separatory funnel to precipitate a white precipitate. The precipitate was taken out by suction filtration and washed with methanol to obtain compound (4). The compound (4) was a white powder, the melting point was 167 to 168 ° C., the yield was 78%, and the yield was 0.40 g.

In addition, the structure of the compound (4) was confirmed as follows.
IR (KBr disc):
ν = 2940, 2868 (> CH ₂ ), 1597, 1499 (C═C), 1252-1190 (C—F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ):
δ = 1.56-1.58 (4H, m), 1.86 (2H, quin, J = 6.4 Hz), 1.88 (2H, quin, J = 6.4 Hz), 2.37-2 .48 (2H, m), 2.56-2.63 (2H, m), 3.14 (2H, m), 3.29 (2H, tt, J = 8.2, 4.0 Hz), 4 .03 (2H, t, J = 6.4 Hz), 4.07 (2H, t, J = 6.4 Hz), 6.97 (2H, d, J = 8.5 Hz), 7.05 (2H, d, J = 9.2 Hz), 7.41 (2H, d, J = 8.5 Hz), 7.51 (2H, d, J = 8.5 Hz), 7.52 (2H, d, J = 7) .9 Hz), 7.84 (2H, d, J = 9.2 Hz) ppm

(Synthesis of Compound L)
4-Bromobenzenethiol (compound K, 11.96 g, 63.29 mmol), 2- (perfluorohexyl) ethyl iodide (30.02 g, 63.33 mmol), potassium carbonate (13.29 g, 96.16 mmol) and acetone 100 mL was placed in a 200 mL eggplant flask and refluxed at 60 ° C. overnight. After the reflux, the contents of the eggplant flask were allowed to stand until it reached room temperature, and transferred to a separatory funnel. Ether, water and saturated brine were added to the separatory funnel to separate the organic layer and the aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by filtering the organic layer was concentrated by an evaporator to obtain a solid. The solid was recrystallized from ethanol to obtain Compound L. Compound L was a white powder, the melting point was 39 to 41 ° C., the yield was 96%, and the yield was 32.41 g.

In addition, the structure of the compound L was confirmed as follows.
IR (KBr disc) measurement results:
ν = 1580, 1477 (C = C), 1248-1140 (C−F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.33-2.43 (2H, m), 3.10 (2H, m), 7.23 (2H, d, J = 8.5 Hz), 7.46 (2H, d, J = 8) .5Hz) ppm

(Synthesis of Compound M)
Compound L (10.00 g, 18.69 mmol), 35% aqueous hydrogen peroxide (6.30 g, 62.96 mmol) and 70 mL of acetic acid were placed in a 100 mL eggplant flask and refluxed at 120 ° C. for 3 days. After the reflux, the contents of the eggplant flask were allowed to stand until it reached room temperature, and transferred to a separatory funnel. An aqueous sodium hydrogen sulfite solution was added to the separatory funnel to precipitate a white precipitate. The precipitate was removed by suction filtration and washed with water to obtain Compound M. Compound M was a white powder, its melting point was 127 to 129 ° C., the yield was 97%, and the yield was 10.22 g.

The structure of Compound M was confirmed as follows.
IR (KBr disc) measurement results:
ν = 1578, 1390 (C = C), 1240-1190 (C—F) cm ^−1
1 H NMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.5-2.65 (2H, m), 3.33 (2H, m), 7.77 (2H, d, J = 8.5 Hz), 7.81 (2H, d, J = 8) .5Hz) ppm

(Synthesis of Compound N)
Compound M (4.67 g, 8.23 mmol), Compound B (1.50 g, 9.87 mmol), Sodium carbonate (1.75 g, 16.45 mmol), Palladium (II) acetate (0.01 g, 0.54 mol%) ), Triphenylphosphine (0.03 g, 1.4 mol%), 20 mL of water and 80 mL of 1,4-dioxane were placed in a 200 mL eggplant flask and refluxed at 100 ° C. for 12 hours under a nitrogen atmosphere. After the reflux, the mixture was allowed to stand until it reached room temperature, and neutralized by adding 50 mL of 1N dilute hydrochloric acid in an air atmosphere. Thereafter, a solid was obtained by suction filtration. The solid was dissolved in chloroform and suction filtered. Thereafter, the obtained filtrate was concentrated with an evaporator to obtain a solid. The solid was purified by a silica gel column to obtain Compound N. Compound N was a white powder, the melting point was 187 to 189 ° C., the yield was 99%, and the yield was 4.85 g.

The structure of Compound N was confirmed as follows.
IR (KBr disc) measurement results:
ν = 1609, 1528 (C = C), 1249 (> O), 1233-1140 (C−F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 2.58-2.69 (2H, m), 3.36 (2H, m), 3.88 (3H, s), 7.03 (2H, d, J = 8.5 Hz), 7. 58 (2H, d, J = 8.5 Hz), 7.77 (2H, d, J = 8.5 Hz), 7.96 (2H, d, J = 8.5 Hz) ppm

(Synthesis of Compound O)
Compound N (2.00 g, 3.37 mmol), boron tribromide (2.60 g, 10.38 mmol) and 50 mL of dichloromethane were placed in a 200 mL eggplant flask, stirred in an ice bath for 2 hours, and returned to room temperature. Stir for 12 hours. Then, after adding water and stirring in an ice bath for 1 hour, the contents were transferred to a separatory funnel. Ether was added to the separatory funnel to separate an organic layer and an aqueous layer. Magnesium sulfate (anhydrous) was added to the resulting organic layer and left for 1 hour. Thereafter, the filtrate obtained by fold filtration of the organic layer was concentrated with an evaporator to obtain Compound O. Compound O was a white powder, the melting point was 207-209 ° C., the yield was 85%, and the yield was 1.65 g.

The structure of Compound O was confirmed as follows.
IR (KBr disc) measurement results:
ν = 3445 (O—H), 1611, 1489 (C═C), 1230-1190 (C—F) cm ^−1
1 HNMR (500 MHz, DMSO-d ₆ ) measurement results:
δ = 2.5-2.66 (2H, m), 3.72 (2H, m), 6.90 (2H, d, J = 8.5 Hz), 7.64 (2H, d, J = 8) .5Hz), 7.90 (2H, d, J = 8.5 Hz), 7.98 (2H, d, J = 8.5 Hz), 9.82 (1H, s) ppm

(Synthesis of Compound (5))
Compound O (0.47 g, 0.810 mmol), Compound I (0.50 g, 0.787 mmol), potassium carbonate (0.17 g, 1.23 mmol) and 3-pentanone 50 mL were placed in a 100 mL eggplant flask and 120 ° C. At reflux overnight. After the reflux, the contents of the eggplant flask were allowed to stand until it reached room temperature, and transferred to a separatory funnel. Water was added to the separatory funnel to precipitate a white precipitate. The precipitate was removed by suction filtration and washed with methanol to obtain compound (5). The compound (5) was a white powder, the melting point was 158 to 160 ° C., the yield was 67%, and the yield was 0.60 g.

In addition, the structure of the compound (5) was confirmed as follows.
IR (KBr disc) measurement results:
ν = 2940, 2868 (> CH ₂ ), 1597, 1497 (C═C), 1234-1190 (C—F) cm ^−1
1 HNMR (500 MHz, CDCl ₃ ) measurement results:
δ = 1.83 (2H, quin, J = 6.4 Hz), 1.86 (2H, quin, J = 6.4 Hz), 2.28-2.38 (2H, m), 2.58-2 .69 (2H, m), 2.99 (2H, m), 3.35 (2H, m), 3.98 (2H, t, J = 6.4 Hz), 4.04 (2H, t, J = 6.4 Hz), 6.87 (2H, d, J = 8.5 Hz), 7.01 (2H, d, J = 8.5 Hz), 7.37 (2H, d, J = 8.5 Hz) 7.57 (2H, d, J = 8.5 Hz), 7.77 (2H, d, J = 8.5 Hz), 7.96 (2H, d, J = 8.5 Hz) ppm

  With respect to the electrolytic solutions (a) to (h) of Examples 1 to 5 and Comparative Examples 1 to 5, gelation ability, gel stability, and electrical conductivity were measured. The results are shown in Table 1. Moreover, about the battery (a), (d), (f), (i) of Examples 6-7 and Comparative Examples 6-7, discharge capacity was measured and cycle characteristics were evaluated. The results are shown in Table 2. Further, safety tests were performed on the electrolyte solutions (a), (d), (f), and (i) of Example 1, Example 4, and Comparative Examples 1 and 4. The results are shown in Table 3.

Claims (9)

An electrolytic solution containing a nonaqueous solvent, an electrolyte, and a compound represented by the following general formula (1).
Rf-R-X-Ar-Z-Ar'-X'-R'-Rf '(1)
(In General Formula (1), Rf and Rf ′ each independently represents a substituted or unsubstituted perfluoroalkyl group having 2 to 18 carbon atoms in the main chain, and R and R ′ each independently represent a single bond or A substituted or unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms in the main chain; X and X ′ each independently represent an S atom, an O atom, an SO group or an SO ₂ group; 'Is a different group, Ar and Ar' each independently represents a substituted or unsubstituted aromatic group or alicyclic group having 5 to 20 ring-forming atoms, and Ar and Ar 'are different groups. Yes, Z represents a substituted or unsubstituted divalent hydrocarbon group or oxyhydrocarbon group having 1 to 8 carbon atoms in the main chain.   2. The electrolytic solution according to claim 1, wherein Ar and Ar ′ are each independently a substituted or unsubstituted phenylene group, biphenylene group, terphenylene group, naphthylene group, anthranylene group, or pyridylene group.   2. The electrolytic solution according to claim 1, wherein Ar and Ar ′ are each independently a substituted or unsubstituted phenylene group, biphenylene group, or naphthylene group. The electrolyte solution according to claim 1, wherein X and X ′ are each independently an S atom, an SO group, or an SO ₂ group. Any one of the Ar and Ar ′ is a phenylene group, the other is a biphenylene group, and one of X and X ′ is an S atom and the other is an SO ₂ group. The electrolyte solution according to item.   The electrolytic solution according to claim 1, wherein the electrolytic solution is a gelled gel electrolyte. A positive electrode containing a positive electrode active material;
A negative electrode containing a negative electrode active material;
The electrolyte solution according to any one of claims 1 to 6,
A lithium ion secondary battery comprising:   The lithium ion secondary battery according to claim 7, wherein the positive electrode active material includes a lithium-containing compound.   The negative electrode active material contains at least one material selected from the group consisting of metallic lithium, a carbon material, a material containing an element capable of forming an alloy with lithium, and a lithium-containing compound. The lithium ion secondary battery as described.