JP6642160B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery using the same.

With the rapid progress of portable electronic devices such as mobile phones and notebook personal computers, demands for higher capacity of batteries used for a main power supply and a backup power supply have been increased, and nickel-cadmium batteries and nickel-cadmium batteries have been required. A non-aqueous electrolyte battery such as a lithium ion secondary battery having a higher energy density than a hydrogen battery has attracted attention.
As an electrolyte for a lithium ion secondary battery, an electrolyte such as LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃ (CF ₂ ) ₃ SO _{3 is used to} convert a high dielectric constant such as ethylene carbonate or propylene carbonate. A typical example is a non-aqueous electrolyte dissolved in a mixed solvent of a solvent and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  In addition, as a negative electrode active material of a lithium ion secondary battery, a carbonaceous material capable of occluding and releasing lithium ions is mainly used, and natural graphite, artificial graphite, amorphous carbon, and the like are typical examples. No. Further, a metal or alloy-based negative electrode using silicon, tin, or the like for higher capacity is also known. As the positive electrode active material, a transition metal composite oxide that can mainly occlude and release lithium ions is used, and typical examples of the transition metal include cobalt, nickel, manganese, and iron.

Such a lithium ion secondary battery uses a highly active positive electrode and negative electrode, and it is known that the side reaction between the electrode and the electrolyte reduces the charge / discharge capacity, improving the battery characteristics. For this purpose, various studies have been made on non-aqueous organic solvents and electrolytes.
Patent Literature 1 proposes a technique for improving the high-temperature storage characteristics of a battery by using an electrolyte solution to which alkyl nitrile is added.

  Patent Document 2 proposes a technique for improving the high-temperature storage characteristics of a battery and the permeability of an electrolyte to a separator by using an electrolyte to which a long-chain alkyl nitrile is added. Patent Literature 3 discloses that an ethylene carbonate, a chain carbonate, a cyclic carbonate having at least one carbon-carbon unsaturated bond, and a nitrile compound are mixed at a specific ratio and used as a solvent for the electrolyte. There has been proposed a technique for improving the ionic conductivity.

Patent Literature 4 proposes a technique for improving the cycle characteristics of a battery by using an electrolytic solution in which a nitrile and an S ＝ O group-containing compound are simultaneously added.
Patent Document 5 proposes a technique for improving the safety of a battery by using an electrolytic solution containing an aliphatic nitrile compound and a halogenated ethylene carbonate at the same time.
Patent Document 6 proposes a technique for improving the conductivity of an electrolytic solution by using a cyanoalkyl carboxylate or a cyanoalkyl carbonate as a solvent for the electrolytic solution.

Patent Document 7 proposes a technique for improving high-temperature storage characteristics and cycle characteristics of a battery by using an electrolytic solution to which a nitrile having a specific structure is added.
Patent Document 8 proposes a technique for improving the high-temperature storage characteristics of a battery by adding a nitrile having a specific structure at the time of manufacturing a positive electrode.

JP-A-10-189008 JP 2011-003364 A JP-A-2004-303437 JP 2004-179146 A JP-T-2009-523305 JP 2000-113906 A JP 2009-259472 A US Patent Application Publication No. 2013/0171522

The nitriles having a saturated hydrocarbon group described in Patent Literatures 1 to 7 have a problem that the battery characteristics are deteriorated by undergoing a reduction side reaction at the negative electrode. In addition, the technique described in Patent Document 8 has a problem in that the nitrile compound is localized on the electrode plate when the electrode is applied, and uneven application of the electrode occurs, thereby deteriorating the battery characteristics. .
The present invention has been made to solve the above-described problems, and in a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte that improves the initial battery characteristics and / or the battery characteristics after a high-temperature durability test; It is an object to provide a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte.

The present inventors have conducted various studies in order to achieve the above object, and as a result, found that the above problem can be solved by including a specific nitrile in an electrolytic solution, thereby completing the present invention. .
The gist of the first aspect of the present invention is as follows.
(A) A non-aqueous electrolyte solution for a non-aqueous electrolyte secondary battery having a positive electrode and a negative electrode capable of occluding and releasing metal ions, wherein the non-aqueous electrolyte solution together with an electrolyte and a non-aqueous solvent are represented by the formula (1). A non-aqueous electrolyte solution comprising the compound represented by the formula (I).

(Where
R ¹ is a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a fluorine atom,
R ² and R ³ are each independently a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, and among R ¹ , R ² and R ³ At least two may form a ring,
n is an integer of 1 or more. However, when n is 2 or more, a plurality of R ² and R ³ may be the same or different. )
(B) The nonaqueous electrolytic solution according to (a), wherein in the formula (1), n is an integer of 2 or more.
(C) The nonaqueous electrolytic solution according to (a) or (b), wherein the nonaqueous electrolytic solution contains the carbonyl compound represented by the formula (1) in an amount of 0.001% by mass or more and 10% by mass or less. liquid.
(D) the non-aqueous electrolyte further comprises a fluorine-containing cyclic carbonate, a sulfur-containing organic compound,
Phosphorus-containing organic compound, organic compound having a cyano group other than the above formula (1), organic compound having an isocyanate group, silicon-containing compound, aromatic compound, cyclic carbonate having a carbon-carbon unsaturated bond, fluorine-free carboxylic acid At least one selected from the group consisting of an ester, a cyclic compound having a plurality of ether bonds, a compound having an isocyanuric acid skeleton, a monofluorophosphate, a difluorophosphate, a borate, an oxalate, and a fluorosulfonate The non-aqueous electrolyte solution according to any one of (a) to (c), which contains the compound of (a) to (c).
(E) The fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphorus-containing organic compound, organic compound having a cyano group other than the formula (1), organic compound having an isocyanate group, silicon-containing compound, aromatic compound, carbon- Cyclic carbonate having carbon unsaturated bond, fluorine-free carboxylic acid ester, cyclic compound having plural ether bonds, compound having isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, borate, oxalate The non-aqueous electrolyte according to (d), wherein the total content of at least one compound selected from the group consisting of and a sulfonate is 0.001% by mass or more and 30% by mass or less based on the total amount of the non-aqueous electrolyte. liquid.

Furthermore, the present invention relates to the following.
(F) A non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte is (a) to A non-aqueous electrolyte secondary battery according to any one of (e).

According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery capable of providing a non-aqueous electrolyte secondary battery having excellent initial battery characteristics and excellent battery characteristics after a durability test, and a non-aqueous electrolyte secondary battery , High performance and high safety can be achieved.
The non-aqueous electrolyte secondary battery produced using the non-aqueous electrolyte solution of the present invention, and the non-aqueous electrolyte secondary battery of the present invention have the effect of simultaneously improving the initial battery characteristics and the battery characteristics after the durability test. -Although the principle is not clear, it can be considered as follows. However, the present invention is not limited to the operation and principle described below.

Usually, a cyano group is directly bonded to an alkyl nitrile represented by Patent Documents 1 to 5, a cyanoalkyl carboxylate and a cyanoalkyl carbonate represented by Patent Document 6, or a carbonyl group or a sulfonyl group represented by Patent Document 7. The compound improves battery characteristics by coordinating the cyano group to the metal oxide in the positive electrode active material. However, at the same time, since the reduction resistance at the negative electrode is low, the reduction side reaction remarkably proceeds on the negative electrode. In particular, in a compound in which a cyano group is directly bonded to a carbonyl group or a sulfonyl group, the reduction side reaction on the negative electrode proceeds more remarkably because the free orbits of the carbonyl group or the sulfonyl group and the cyano group overlap with each other. Further, the reduction side reaction cannot be suppressed even by using an additive known as a negative electrode film forming agent in combination. As a result, a large amount of a film having a low Li ⁺ conductivity is formed, so that the charge / discharge characteristics and the charge / discharge efficiency under a high current density can be significantly reduced. Furthermore, the discharge capacity can be significantly reduced due to the remarkable progress of the reduction side reaction.

With respect to such a problem, the first aspect of the present invention has found that the above problem can be solved by including the compound represented by the formula (1) in a non-aqueous electrolyte.
As described below, the compound represented by the formula (1) has a carbonyl group and a cyano group via a hydrocarbon group. Therefore, a chelate structure can be obtained by coordinating the carbonyl group and the cyano group to the positive electrode metal. Furthermore, by oxidizing the carbonyl group from the chelated state, the polymerization reaction originating from the carbonyl group origin proceeds, and a stable protective film can be formed on the positive electrode.

Further, the compound represented by the formula (1) can have a coordination chelate structure with Li ⁺ by a carbonyl group and a cyano group. As a result, the solvation energy is higher than that of the carbonate, so that it is possible to approach the negative electrode surface as close as possible. Furthermore, a carbonyl group site is reduced in the vicinity of the negative electrode surface, so that a stable protective film having high Li ⁺ conductivity can be selectively formed on the outermost surface of the negative electrode. As a result, the reduction side reaction at the negative electrode is significantly suppressed, and the initial battery characteristics and the battery characteristics after the durability test can be improved without lowering the battery characteristics.

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
1. Non-aqueous electrolyte 1-1. Compound represented by formula (1) A first aspect of the present invention is characterized in that a compound represented by formula (1) is contained in a non-aqueous electrolyte. In the compound represented by the formula (1), no distinction is made between optical isomers, and the compound can be applied alone or as a mixture thereof.

(Where
R ¹ is a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a fluorine atom,
R ² and R ³ are each independently a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, and among R ¹ , R ² and R ³ At least two may form a ring,
n is an integer of 1 or more. However, when n is 2 or more, a plurality of R ² and R ³ may be the same or different. )
In the formula (1), when n is 2 or more, a plurality of R ² and R ³ are present, respectively, but a plurality of R ² and a plurality of R ³ may be the same or different. .

In Formula (1), when a ring is formed by at least two of R ¹ , R ² and R ³ , it is preferable that R ¹ and R ² be bonded to each other to form a ring. This is because the chelate structure is easily formed with respect to Li ⁺ , so that it is possible to approach the negative electrode surface nearest to the negative electrode surface, and more stable negative electrode films can be formed.
When n is 2 or more, a plurality of R ² and R ³ are present, but R ² and R ³ which are not bonded to the same carbon atom are bonded to each other to form a ring. May be.

In the formula (1), R ¹ is a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, and may be substituted with a hydrogen atom or a fluorine atom. It is preferably a hydrocarbon group having 1 to 12 carbon atoms, and more preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a fluorine atom. The carbon number of the hydrocarbon group in R ¹ is not particularly limited in order to exhibit the effects of the present invention, but is usually 1 or more, preferably 10 or less, more preferably 9 or less, further preferably 5 or less, and particularly preferably 5 or less. Preferably it is 4 or less. When R ¹ is within the above range, it is possible to approach the negative electrode surface nearest to the negative electrode surface, and more stable negative electrode films can be formed, which is preferable.

  Here, the hydrocarbon group represents a group composed of a carbon atom and a hydrogen atom, and corresponds to an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group is an acyclic or cyclic hydrocarbon group composed of a carbon atom and a hydrogen atom, and represents a group having no aromatic structure. Further, the aromatic hydrocarbon group refers to a hydrocarbon group having an aromatic structure composed of carbon atoms and hydrogen atoms.

  Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, and an alkynyl group, and an aromatic hydrocarbon group such as an aryl group and an aralkyl group, and are preferably an aliphatic hydrocarbon group, and more preferably. Is an alkyl group. This is because a protective film can be efficiently formed on the negative electrode.

  Of these, methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl, tert-butyl, n-pentyl, isopentyl, sec- Alkyl groups having 1 to 5 carbon atoms such as pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl group, 1-propenyl group, 2 to 5 carbon atoms such as 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group and 4-pentenyl group Alkenyl group; ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl Alkynyl groups having 2 to 5 carbon atoms such as, 3-pentynyl and 4-pentynyl; phenyl, tolyl, xylyl, ethylphenyl, n-propylphenyl, i-propylphenyl and n-butylphenyl Groups, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group and other aryl groups; benzyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, phenethyl group, 2-phenylpropyl Group, 2-methyl-2-phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenylbutyl group, 4-phenylbutyl group, 5-phenylpentyl group, 6-phenylhexyl An aralkyl group having 7 to 12 carbon atoms such as a group is preferable. More preferably, methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl, tert-butyl, n-pentyl, isopentyl, sec- Alkyl groups having 1 to 5 carbon atoms such as pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl group, 1-propenyl group, 2 to 5 carbon atoms such as 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group and 4-pentenyl group Benzyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, phenethyl group, 2-phenylpropyl group, 2-methyl-2- 7 to 12 carbon atoms such as phenylpropyl group, 3-phenylpropyl group, 3-phenylbutyl group, 3-methyl-3-phenylbutyl group, 4-phenylbutyl group, 5-phenylpentyl group and 6-phenylhexyl group. And more preferably a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a benzyl group, a phenethyl group, a 3-phenylpropyl group, a 4-phenylbutyl group, and a methyl group, an ethyl group Groups, n-propyl groups and n-butyl groups are particularly preferred. This is because a protective film can be efficiently formed on the negative electrode.

A hydrocarbon group substituted by a fluorine atom can also be preferably used. Specific examples of the hydrocarbon group substituted with a fluorine atom include fluoromethyl group, fluoroethyl group, difluoroethyl group, trifluoroethyl group, perfluoroethyl group, fluoro-n-propyl group, difluoro-n-propyl Group, trifluoro-n-propyl group, perfluoro-n-propyl group, fluoro-n-butyl group, difluoro-n-butyl group, trifluoro-n-butyl group, perfluoro-n-butyl group and the like are preferable. . The above-mentioned hydrocarbon group substituted with a fluorine atom has high stability of the compound.

In the formula (1), R ² and R ³ are independently a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, and these are bonded to each other. May form a ring. Among them, a hydrocarbon group having 1 to 12 carbon atoms which may have a hydrogen atom and a substituent is preferable, and a hydrocarbon group having 1 to 12 carbon atoms having no hydrogen atom and a substituent is more preferable. And a hydrogen atom is more preferred.

When R ² and R ³ are a hydrocarbon group which may have a substituent, the number of carbon atoms of the hydrocarbon group is not particularly limited for achieving the effects of the present invention, but is usually 1 or more. On the other hand, it is usually 8 or less, preferably 4 or less, more preferably 2 or less. It is preferable that R ² and R ³ are within the above ranges, since side reaction deterioration on the positive electrode is small.
Here, the substituent means a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a fluorine atom (however, a carbon atom and a hydrogen atom Excluding a group consisting only of).

  As the substituent, a fluorine atom; an alkoxy group; an alkoxy group substituted by a fluorine atom; a cyano group, an isocyanato group, an alkoxycarbonyloxy group; an acyl group; a carboxy group; an alkoxycarbonyl group; an acyloxy group; an alkylsulfonyl group; A sulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group, and the like, preferably a fluorine atom, a cyano group, an isocyanato group, or an alkoxycarbonyl group, and more preferably a fluorine atom or a cyanocarbonyl group. Group. The above substituents are preferable because of high stability of the compound. In addition, as an alkoxy group in the said substituent, a C1-C6 thing is mentioned, for example.

Examples of the hydrocarbon group include an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group and an alkynyl group, and an aromatic hydrocarbon group such as an aryl group and an aralkyl group, and are preferably an aliphatic hydrocarbon group, and more preferably. Is an alkyl group. This is because a protective film can be efficiently formed on the negative electrode.
Among them, alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group and tert-butyl group; An alkenyl group having 2 to 4 carbon atoms such as a vinyl group, a 1-propenyl group, a 2-propenyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group; an ethynyl group, a 1-propynyl group, An alkynyl group having 2 to 4 carbon atoms such as a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group; a phenyl group, a tolyl group, a xylyl group, an ethylphenyl group, an n-propylphenyl group, i Aryl groups such as -propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group and tert-butylphenyl group; benzyl group, α-methylben Phenyl, 1-methyl-1-phenylethyl, phenethyl, 2-phenylpropyl, 2-methyl-2-phenylpropyl, 3-phenylpropyl, 3-phenylbutyl, 3-methyl-3- An aralkyl group having 7 to 12 carbon atoms such as a phenylbutyl group, a 4-phenylbutyl group, a 5-phenylpentyl group, and a 6-phenylhexyl group is preferable, and a methyl group, an ethyl group, an n-propyl group, i -Alkyl groups having 1 to 4 carbon atoms such as -propyl group, n-butyl group, sec-butyl group, i-butyl group and tert-butyl group, and more preferably methyl group or ethyl group. The above substituents are preferable since side reaction deterioration on the positive electrode is small.

A hydrocarbon group having a substituent can also be preferably used. Examples of the substituent include a fluorine atom, a cyano group-substituted alkyl group, and a fluorine atom-substituted alkyl group. Examples of the hydrocarbon group having a substituent include a cyanomethyl group, a 1-cyanoethyl group, a 2-cyanoethyl group, a 1-cyano-n-propyl group, a 2-cyano-n-propyl group, a 3-cyano-n-propyl group, 1-cyano-n-butyl group, 2-cyano-n-butyl group, 3-cyano-n-butyl group, 4-cyano-n-butyl group, fluoromethyl group, fluoroethyl group, difluoroethyl group, trifluoro Ethyl group, perfluoroethyl group, fluoro-n-propyl group, difluoro-n-propyl group, trifluoro-n-propyl group, perfluoro-n-propyl group, fluoro-n-butyl group, difluoro-n-butyl Group, trifluoro-n-butyl group, perfluoro-n-butyl group and the like. The above substituents are preferable because side reaction deterioration in the positive electrode is small.

When a ring is formed by at least two members out of R ¹ , R ² and R ³ , the cyclic structure is not particularly limited in order to exhibit the effects of the present invention. A structure consisting of a nitrogen atom, an oxygen atom and a sulfur atom is preferred, and a structure consisting of a carbon atom is more preferred. The number of ring members in the cyclic structure is not particularly limited, but is usually 3 or more, preferably 4 or more, more preferably 5 or more, while usually 12 or less, preferably 8 or less, more preferably 7 or less, and further more preferably 6 or less. It is. When the ring skeleton is composed of carbon atoms, the total number of carbon atoms constituting the ring is usually 3 or more, preferably 4 or more, more preferably 5 or more, and usually 12 or less, preferably 8 or less, more preferably It is 7 or less, more preferably 6 or less. It is preferable to satisfy the above conditions because the stability of the compound is high.

Specific examples of the cyclic structure include a cycloalkane structure, an oxacycloalkane structure, an azacycloalkane structure, and a thiacycloalkane structure. Among them, cycloalkane structures having 3 to 12 carbon atoms such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, cycloundecane structure, and cyclododecane structure. And more preferably a cyclopropane structure, a cyclobutane structure, a cyclopentane structure and a cyclohexane structure, more preferably a cyclopentane structure and a cyclohexane structure, and particularly preferably a cyclohexane structure. When R ¹ and R ² or R ³ are bonded to each other to form a ring, a part of the ring structure may have a structure substituted by a carbonyl group. The above structure is preferable because the stability of the compound is high.

In the formula (1), n is not particularly limited to exhibit the effects of the present invention except for being an integer of 1 or more, but is preferably an integer of 2 or more, more preferably 3 or more. Usually, it is 12 or less, preferably 10 or less, more preferably 6 or less, still more preferably 5 or less, and particularly preferably 4 or less.
When the content is within the above range, the chelate stabilization energy for Li ⁺ becomes large, the effect of the present invention is easily exhibited, and the reduction side reaction of the compound at the negative electrode is easily suppressed.

Examples of the compound represented by the formula (1), the compounds mentioned ^below, at least one of R 1, ^{R 2} and, if not forming a ring by at least two of the ^R 1 ^{R 3, R 2} and ^{R 3} Two may form a ring. Among these, the case where a ring is not formed by at least two of R ¹ , R ² and R ³ is preferable because the effect of the present invention provided by the chelate stabilizing effect is easily exhibited.

-When a ring is not formed by at least two of R ¹ , R ² and R ³

  Of these, the following compounds are preferred from the viewpoint of high reactivity on the positive electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of high film-forming ability on the negative electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of reducing the oxidation side reaction on the positive electrode and the reduction reaction on the negative electrode.

When a ring is formed by at least two of R ¹ , R ² and R ³

  Of these, the following compounds are preferred from the viewpoint of high reactivity on the positive electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of high film-forming ability on the negative electrode.

  Further, among these, the following compounds are more preferable from the viewpoint of reducing the oxidation side reaction on the positive electrode and the reduction reaction on the negative electrode.

  The compounds represented by the formula (1) may be used alone or in combination of two or more. The amount of the compound represented by the formula (1) in the total amount of the nonaqueous electrolyte (100% by mass) (the total amount in the case of two or more types) is not particularly limited in order to exhibit the effects of the present invention. Is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, Further, it is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. It is. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  In addition, the method of blending the above compound with the electrolytic solution of the present invention is not particularly limited. In addition to the method of directly adding the compound to the electrolytic solution, a method of generating the compound in a battery or in the electrolytic solution may be mentioned. Examples of a method for generating the above compound include a method in which a compound other than these compounds is added, and a battery component such as an electrolyte is generated by oxidation or hydrolysis. Further, a method of producing a battery by applying an electrical load such as charge / discharge after producing the battery can also be mentioned.

  In addition, when the above compound is contained in a non-aqueous electrolyte and is actually used for producing a non-aqueous electrolyte secondary battery, even if the battery is disassembled and the non-aqueous electrolyte is extracted again, the content in the non-aqueous electrolyte is reduced. In many cases, it has dropped significantly. Therefore, those in which the above compound can be detected in a very small amount from the non-aqueous electrolyte extracted from the battery are considered to be included in the present invention. Further, when the above compound is actually used as a non-aqueous electrolyte solution for producing a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte solution which is disassembled and re-extracted contains only a very small amount of the compound. Even in the case where the battery is not provided, it is often detected on the positive electrode, the negative electrode, or the separator, which is another component of the non-aqueous electrolyte secondary battery. Therefore, when the above compounds are detected from the positive electrode, the negative electrode, and the separator, it can be assumed that the total amount was contained in the non-aqueous electrolyte. Under this assumption, it is preferable that the specific compound is included in the range described below.

1-2. Fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphorus-containing organic compound, organic compound having a cyano group, organic compound having an isocyanate group, silicon-containing compound, aromatic compound, cyclic carbonate having a carbon-carbon unsaturated bond, fluorine-free Containing carboxylic acid ester, a cyclic compound having a plurality of ether bonds and a compound having an isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, borate, oxalate, and fluorosulfonate Along with the compound represented by the formula (1), a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group other than the formula (1), an organic compound having an isocyanate group, and a silicon-containing compound , Aromatic compounds, cyclic having carbon-carbon unsaturated bonds Consists of carbonate, fluorine-free carboxylic acid ester, cyclic compound having multiple ether bonds and compound having isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate At least one compound selected from the group (compounds of group (II)). By using these together, side reactions on the positive and negative electrodes which can be caused by the compound represented by the formula (1) can be efficiently suppressed.

  Among them, a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group other than the formula (1), an aromatic compound, a cyclic carbonate having a carbon-carbon unsaturated bond, and a fluorine-free carboxylic acid At least one compound selected from the group consisting of an ester and a cyclic compound having a plurality of ether bonds forms a high-quality composite coating on the negative electrode, and improves the initial battery characteristics and the battery characteristics after the durability test in a well-balanced manner. At least one selected from the group consisting of a fluorine-containing cyclic carbonate, an organic compound having a cyano group other than the formula (1), an aromatic compound, a cyclic carbonate having a carbon-carbon unsaturated bond, and a carboxylic acid ester. Compounds are more preferred, having fluorine-containing cyclic carbonate, carbon-carbon unsaturated bond At least one compound are more preferably selected from the group consisting of cyclic carbonates and carboxylic acid esters, fluorine-containing cyclic carbonate or carbon - at least one compound selected from cyclic carbonates having a carbon unsaturated bond is particularly preferred. The reason is that these compounds, which form a relatively low-molecular-weight film on the negative electrode, efficiently suppress the deterioration of the compound represented by the formula (1) due to the side reaction because the formed negative electrode film is dense. What can be done. In this way, it is possible to effectively suppress side reactions and also suppress a rise in resistance, suppress volume changes by suppressing side reactions during initial or high-temperature endurance, secure safety after high-temperature endurance, and improve rate characteristics. .

  The method for blending the above compound with the electrolytic solution of the present invention is not particularly limited. In addition to the method of directly adding the compound to the electrolytic solution, a method of generating the compound in a battery or in the electrolytic solution may be mentioned. Examples of a method for generating the above compound include a method in which a compound other than these compounds is added, and a battery component such as an electrolyte is generated by oxidation or hydrolysis. Further, a method of producing a battery by applying an electrical load such as charge / discharge after producing the battery can also be mentioned.

  In addition, when the above compound is contained in a non-aqueous electrolyte and is actually used for producing a non-aqueous electrolyte secondary battery, even if the battery is disassembled and the non-aqueous electrolyte is extracted again, the content in the non-aqueous electrolyte is reduced. In many cases, it has dropped significantly. Therefore, those in which the above compound can be detected in a very small amount from the non-aqueous electrolyte extracted from the battery are considered to be included in the present invention. Further, when the above compound is actually used as a non-aqueous electrolyte solution for producing a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte solution which is disassembled and re-extracted contains only a very small amount of the compound. Even in the case where the battery is not provided, it is often detected on the positive electrode, the negative electrode, or the separator, which is another component of the non-aqueous electrolyte secondary battery. Therefore, when the above compounds are detected from the positive electrode, the negative electrode, and the separator, it can be assumed that the total amount was contained in the non-aqueous electrolyte. Under this assumption, it is preferable that the specific compound is included in the range described below.

  Hereinafter, the compound of the group (II) will be described. However, regarding monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate, 1-4. The description in the electrolyte applies. As for the compound represented by the formula (1) in combination with the above compound, the above description regarding the compound represented by the formula (1) is applied, including examples and preferred examples. Further, in an embodiment containing a certain compound, other compounds of the above compounds may be contained.

1-2-1. Fluorine-containing cyclic carbonate Examples of the fluorine-containing cyclic carbonate include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. For example, fluorinated ethylene carbonate (hereinafter referred to as “fluorinated ethylene carbonate”) In some cases), and derivatives thereof. Examples of the derivative of the fluorinated ethylene carbonate include a fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among them, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferable.

By using the compound represented by the formula (1) in combination with the fluorine-containing cyclic carbonate in the electrolytic solution of the present invention, the initial gas amount can be suppressed in a battery using this electrolytic solution.
Examples of the fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene Carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethyl Le ethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among them, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferable because they impart high ionic conductivity to the electrolytic solution and easily form a stable interfacial protective film.
As the fluorinated cyclic carbonate, one kind may be used alone, and two kinds or more may be used in optional combination and ratio. The amount of the fluorinated cyclic carbonate (the total amount in the case of two or more) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% by mass, in 100% by mass of the electrolytic solution. % By mass or more, still more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, most preferably 1.2% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass. The content is more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 2% by mass or less. When the fluorinated cyclic carbonate is used as the non-aqueous solvent, the compounding amount is preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. The content is preferably 50% by volume or less, more preferably 35% by volume or less, and further preferably 25% by volume or less.

  Further, as the fluorine-containing cyclic carbonate, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes referred to as “fluorinated unsaturated cyclic carbonate”) can also be used. The number of fluorine atoms in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. The fluorine number can be 6 or less, preferably 4 or less, and more preferably 1 or 2.

Examples of the fluorinated unsaturated cyclic carbonate include a fluorinated vinylene carbonate derivative, a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond, and the like.
As the fluorinated vinylene carbonate derivatives, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

Examples of the fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate and 4-fluoro-
4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4, 5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4- Difluoro 5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate.

  Among them, as the fluorinated unsaturated cyclic carbonate, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro -4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, Fluoro-4,5-diallyl carbonate, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl carbonate is preferred because it forms a stable interface protective coating.

  The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited. The molecular weight is preferably 50 or more and 250 or less. Within this range, the solubility of the fluorinated cyclic carbonate in the non-aqueous electrolyte is easily ensured, and the effect of the present invention is easily exhibited. The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and any known method can be used for the production. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

As the fluorinated unsaturated cyclic carbonate, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
The amount of the fluorinated unsaturated cyclic carbonate (in the case of two or more kinds, the total amount) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0% by mass in 100% by mass of the electrolytic solution. 0.1% by mass or more, particularly preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, and particularly preferably 3% by mass or less. It is as follows. Within this range, the non-aqueous electrolyte secondary battery can easily exhibit a sufficient effect of improving the cycle characteristics, and the high-temperature storage characteristics are reduced, the amount of generated gas is increased, and the discharge capacity retention ratio is reduced. It is easy to avoid the situation.

  The mass ratio of the compound represented by the formula (1) to the fluorine-containing cyclic carbonate may be 1: 100 or more, preferably 10: 100, for the compound represented by the formula (1): fluorine-containing cyclic carbonate. 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10,000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, and still more preferably 100: 100 or less. : 100 or less, particularly preferably 75: 100 or less, most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-2. Sulfur-containing organic compound The electrolytic solution of the present invention can further contain a sulfur-containing organic compound. The sulfur-containing organic compound is not particularly limited as long as it has at least one sulfur atom in the molecule, but is preferably an organic compound having an S ＝ O group in the molecule, Sulfonic acid ester, cyclic sulfonic acid ester, chain sulfate ester, cyclic sulfate ester, chain sulfite ester and cyclic sulfite ester. However, those corresponding to fluorosulfonates are as described in 1-2-2. It is not a sulfur-containing organic compound but is included in a fluorosulfonic acid salt, which is an electrolyte described later.

By using the compound represented by the formula (1) in combination with the sulfur-containing organic compound in the electrolytic solution of the present invention, the initial efficiency can be improved in a battery using this electrolytic solution. Acid esters, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites, and cyclic sulfites are preferred, and more preferably compounds having an S (ＯO) ₂ group.

These esters may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom. A group composed of one or more atoms selected from the group consisting of a hydrogen atom, an oxygen atom and a halogen atom, more preferably one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom and an oxygen atom It is a structured group. Examples of the substituent include a halogen atom; an unsubstituted or halogen-substituted alkyl group, alkenyl group, alkynyl group, aryl group or alkoxy group; cyano group; isocyanato group; alkoxycarbonyloxy group; acyl group; carboxy group; Acyloxy group; alkylsulfonyl group; alkoxysulfonyl group; dialkoxyphosphanthryl group; dialkoxyphosphoryl group and dialkoxyphosphoryloxy group. Of these, a halogen atom; an alkoxy group; an unsubstituted or halogen-substituted alkyl group, an alkenyl group or an alkynyl group; an isocyanato group; a cyano group; an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group; And more preferably a halogen atom, an unsubstituted alkyl group or an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group or an acyloxy group, and more preferably a halogen atom, an unsubstituted alkyl group or an alkoxycarbonyl group. Illustrative and preferred examples of these substituents are applied to the substituents in the definition of A ¹² and A ¹³ in the formula (2-2-1) described below and A ¹⁴ in the formula (2-2-2). .

More preferred are chain sulfonic acid esters and cyclic sulfonic acid esters, and among them, chain sulfonic acid esters represented by the formula (2-2-1) and cyclic sulfones represented by the formula (2-2-2) An acid ester is preferable, and a cyclic sulfonic acid ester represented by the formula (2-2-2) is more preferable.
1-2-2-1. A chain sulfonic acid ester represented by the formula (2-2-1)

(Where
A ¹² is of n ²¹ monovalent hydrocarbon radical than 12 unprotected carbon number of 1 or more also have a substituent,
A ¹³ is a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent,
n ²¹ is an integer of 1 or more and 4 or less;
When n ²¹ is 2, A ¹² and A ¹³ may be the same or different. )
In the formula ^{(2-2-1), A 12} and ^{A 13} are ^members not form a ring together, thus the formula (2-2-1) is a chain sulfonic acid esters.

n ²¹ is preferably from 1 to 3 of an integer, more preferably 1 to 2 integer 2 is more preferable.
Examples of the hydrocarbon group having 1 to 12 for ^{n 21} divalent carbon in A ^12,
Monovalent hydrocarbon groups such as alkyl, alkenyl, alkynyl and aryl groups;
Divalent hydrocarbon groups such as alkylene, alkenylene, alkynylene and arylene;
Trivalent hydrocarbon groups such as alkanetriyl groups, alkenetriyl groups, alkynetriyl groups and arenetriyl groups;
Tetravalent hydrocarbon groups such as alkanetetrayl, alkenetetrayl, alkynetetrayl and arenetetrayl;
And the like.

Among these, divalent hydrocarbon groups such as an alkylene group, alkenylene group, alkynylene group and arylene group are preferable, and an alkylene group is more preferable. These correspond to the case where ⁿ²¹ is 2.
Of the ^{n 21-valent} hydrocarbon group having 1 to 12 carbon atoms, monovalent hydrocarbon group, a methyl group, an ethyl group, n- propyl group, i- propyl, n- butyl group, sec- butyl Group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2- C1-C5 alkyl group such as dimethylpropyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group Alkenyl groups having 2 to 5 carbon atoms, such as, pentenyl, 2-pentenyl, 3-pentenyl and 4-pentenyl; ethynyl, 1-propynyl, 2-propynyl, 1-butynyl And alkynyl groups having 2 or more and 5 or less carbon atoms such as a group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group.

  Examples of the divalent hydrocarbon group include an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; a vinylene group, a 1-propenylene group, a 2-propenylene group; Alkenylene groups having 2 to 5 carbon atoms, such as 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group; ethinylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene And an alkynylene group having 2 or more and 5 or less carbon atoms such as a group and a 2-pentynylene group, preferably an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group and the like. And more preferably a charcoal such as ethylene group, trimethylene group, tetramethylene group, pentamethylene group or the like. A number 2 to 5 of the alkylene group, more preferably a trimethylene group, a tetramethylene group, an alkylene group having 3 to 5 carbon atoms, such as pentamethylene group.

Examples of the trivalent and tetravalent hydrocarbon groups include trivalent and tetravalent hydrocarbon groups corresponding to the above-described monovalent hydrocarbon groups.
The of n ²¹ monovalent hydrocarbon group 1 to 12 carbon atoms which have a substituent in the A ^12, a combination of the above hydrocarbon group substituent and the number 1 to 12 of n ^21-valent carbon Means a group. The A ^12, a hydrocarbon group having 1 to 5 inclusive n ²¹ valent carbon preferably has no substituent.

Examples of the hydrocarbon group having 1 to 12 carbon atoms in the A ^13, alkyl group, alkenyl group, a monovalent preferably a hydrocarbon group such as an alkynyl group and an aryl group, an alkyl group is more preferable.
Examples of the hydrocarbon group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl, tert-butyl, and n. An alkyl group having 1 to 5 carbon atoms such as a pentyl group, an isopentyl group, a sec-pentyl group, a neopentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 1,1-dimethylpropyl group, and a 1,2-dimethylpropyl group. And the like, preferably methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, more preferably methyl group, ethyl group, n-propyl group, more preferably ethyl A n-propyl group.

The hydrocarbon group having 1 to 12 carbon atoms having a substituent in A ¹³ means a group obtained by combining the above substituent and the hydrocarbon group having 1 to 12 carbon atoms. A ¹³ is preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent, more preferably a hydrocarbon group having 1 to 5 carbon atoms having a substituent, An alkyl group having an alkoxycarbonyl group as a substituent is more preferred. Among them, methoxycarbonylmethyl group, ethoxycarbonylmethyl group, 1-methoxycarbonylethyl group, 1-ethoxycarbonylethyl group, 2-methoxycarbonylethyl group, 2-ethoxycarbonylethyl group, 1-methoxycarbonylpropyl group, 1-ethoxy A carbonylpropyl group, a 2-methoxycarbonylpropyl group, a 2-ethoxycarbonylpropyl group, a 3-methoxycarbonylpropyl group, and a 3-ethoxycarbonylpropyl group are preferable, and a 1-methoxycarbonylethyl group and a 1-ethoxycarbonylethyl group are more preferable. It is.

  1-2-2-2. Cyclic sulfonic acid ester represented by the formula (2-2-2)

(Where
A ¹⁴ is a divalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent. )
Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms in the A ^14, an alkylene group, an alkenylene group, an alkynylene group and an arylene group and the like, preferably an alkylene group, an alkenylene group.

Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms include an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group; a vinylene group and a 1-propenylene group. , 2-propenylene, 1-butenylene, 2-butenylene, 1-pentenylene, 2-pentenylene, and other alkenylene groups having 2 to 5 carbon atoms; ethynylene, propynylene, 1-butynylene, 2-butynylene And alkynylene groups having 2 to 5 carbon atoms, such as a group, a 1-pentynylene group and a 2-pentynylene group.

  Of these, alkylene groups having 1 to 5 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group and vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group are preferable. And alkenylene groups having 2 to 5 carbon atoms such as 2-butenylene group, 1-pentenylene group and 2-pentenylene group, more preferably alkylene having 3 to 5 carbon atoms such as trimethylene group, tetramethylene group and pentamethylene group. And alkenylene groups having 3 to 5 carbon atoms such as a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, and more preferably a trimethylene group, They are a 1-propenylene group and a 2-propenylene group.

In addition, the divalent hydrocarbon group having 1 to 12 carbon atoms having a substituent in A ¹⁴ is a group obtained by combining the above substituent and the divalent hydrocarbon group having 1 to 12 carbon atoms. Means that. A ¹⁴ is preferably a divalent hydrocarbon group having 1 to 5 carbon atoms having no substituent.
Examples of the sulfur-containing organic compound include the following.

≪Chain sulfonic acid ester≫
Fluorosulfonic acid esters such as methyl fluorosulfonic acid and ethyl fluorosulfonic acid;
Methyl methanesulfonate, ethyl methanesulfonate, 2-propynyl methanesulfonate, 3-butynyl methanesulfonate, busulfan, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2- 2-propynyl (methanesulfonyloxy) propionate, 3-butynyl 2- (methanesulfonyloxy) propionate, methyl methanesulfonyloxyacetate, ethyl methanesulfonyloxyacetate, 2-propynyl methanesulfonyloxyacetate and 3-methanesulfonyloxyacetate Methanesulfonic acid esters such as butynyl;

Methyl vinyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl allyl sulfonate, propargyl allyl sulfonate and 1,2-bis (vinyl sulfonyloxy ) Alkenylsulfonic acid esters such as ethane;
Methoxycarbonylmethyl methanedisulfonic acid, ethoxycarbonylmethyl methanedisulfonic acid, 1-methoxycarbonylethyl methanedisulfonic acid, 1-ethoxycarbonylethyl methanedisulfonic acid, methoxycarbonylmethyl 1,2-ethanedisulfonic acid, 1,2-ethanedisulfonic acid Ethoxycarbonylmethyl, 1-methoxycarbonylethyl 1,2-ethanedisulfonic acid, 1-ethoxycarbonylethyl 1,2-ethanedisulfonic acid, methoxycarbonylmethyl 1,3-propanedisulfonic acid, ethoxycarbonyl 1,3-propanedisulfonic acid Methyl, 1-methoxycarbonylethyl 1,3-propanedisulfonic acid, 1-ethoxycarbonylethyl 1,3-propanedisulfonic acid, methoxycarbonyl 1,3-butanedisulfonic acid Methyl, 1,3-butane disulfonic acid ethoxycarbonylmethyl, 1,3-butane disulfonic acid 1-methoxycarbonyl-ethyl, alkyl disulfonic acid esters, such as 1,3-butane disulfonic acid 1-ethoxycarbonylethyl;

≪Cyclic sulfonic acid ester≫
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone , 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-prope -1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3 Sultone compounds such as -methyl-2-propene-1,3-sultone, 1,4-butanesultone and 1,5-pentanesultone;

Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazole-2,2-dioxide 5H-1,2,3-oxathiazol-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide, 1, 2,3-oxathiazinan-2,2-dioxide, 3-methyl-1,2,3-oxathiazinan-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine-2,2-dioxide and Nitrogen-containing compounds such as 1,2,4-oxathiazinane-2,2-dioxide.

  1,2,3-oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathi Afoslan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiafoslan-2,2,3-trioxide, 1,2,4-oxathiafoslan-2,2-dioxide , 1,2,5-oxathiaphosphane-2,2-dioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan- 2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinan-2,2,3- Trioxide, 1,2,4-oxathiaphosphite Down-dioxide, 1,2,5-oxathiazolium phosphinothricin Nan-2,2-dioxide and 1,2,6-oxa-thia phosphinothricin Nan -2,2-containing phosphorus compounds such as dioxide.

≪Chain sulfate 硫酸
Dialkyl sulfate compounds such as dimethyl sulfate, ethyl methyl sulfate and diethyl sulfate.
≪Cyclic sulfate≫
1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,4-butylene sulfate, 1, Alkylene sulfate compounds such as 2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate and 1,5-pentylene sulfate.

≪Chain sulfite≫
Dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite and diethyl sulfite.
≪Cyclic sulfite≫
1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite, 1,3-butylene sulfite, 1,4-butylene sulfite, 1, Alkylene sulfite compounds such as 2-pentylene sulfite, 1,3-pentylene sulfite, 1,4-pentylene sulfite, and 1,5-pentylene sulfite.

  Of these, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl 2- (methanesulfonyloxy) propionate, 1-methoxycarbonylethyl propanedisulfonate, propanedisulfone 1-ethoxycarbonylethyl acid, 1-methoxycarbonylethyl butanedisulfonic acid, 1-ethoxycarbonylethyl butanedisulfonic acid, 1,3-propanesultone, 1-propene-1,3-sultone, 1,4-butanesultone, 1, 2-Ethylene sulfate, 1,2-ethylene sulfite, methyl methanesulfonate and ethyl methanesulfonate are preferred from the viewpoint of improving the initial efficiency, and 1-methoxycarbonylethyl propanedisulfonic acid and 1-e-propanedisulfonic acid are preferred. Xycarbonylethyl, 1-methoxycarbonylethyl butanedisulfonic acid, 1-ethoxycarbonylethyl butanedisulfonic acid, 1,3-propanesultone, 1-propene-1,3-sultone, 1,2-ethylenesulfate, 1,2 -Ethylene sulfite is more preferred, and 1,3-propane sultone and 1-propene-1,3-sultone are still more preferred.

As the sulfur-containing organic compound, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
The content of the sulfur-containing organic compound (the total amount in the case of two or more kinds) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 100% by mass in the electrolytic solution. 0.1% by mass or more, particularly preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, It is more preferably at most 3% by mass, further preferably at most 2% by mass, particularly preferably at most 1.5% by mass, most preferably at most 1.0% by mass. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  The mass ratio of the compound represented by the above formula (1) to the sulfur-containing organic compound can be 1: 100 or more, preferably 10: 100, for the compound represented by the formula (1): sulfur-containing organic compound. 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10,000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, and still more preferably 100: 100 or less. : 100 or less, particularly preferably 75: 100 or less, most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-3. Phosphorus-containing organic compound The electrolytic solution of the present invention can further contain a phosphorus-containing organic compound. The phosphorus-containing organic compound is not particularly limited as long as it has at least one phosphorus atom in the molecule. A battery using the electrolytic solution of the present invention containing a phosphorus-containing organic compound has suppressed gas generation after storage at high temperatures, has a good recovery rate, and has good initial charge / discharge efficiency.

As the phosphorus-containing organic compound, a phosphoric acid ester, a phosphonic acid ester, a phosphinic acid ester, and a phosphite ester are preferable, a phosphoric acid ester and a phosphonic acid ester are more preferable, and a phosphonic acid ester is more preferable. These esters may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom. , A hydrogen atom, an oxygen atom and a halogen atom. Examples of the substituent include a halogen atom; an unsubstituted or halogen-substituted alkyl group, alkenyl group, alkynyl group, aryl group or alkoxy group; cyano group; isocyanato group; alkoxycarbonyloxy group; acyl group; carboxy group; Acyloxy group; alkylsulfonyl group; alkoxysulfonyl group; dialkoxyphosphanthryl group; dialkoxyphosphoryl group and dialkoxyphosphoryloxy group. Of these, preferred are a halogen atom; an alkoxy group; an alkoxycarbonyloxy group; an acyl group; a carboxyl group and an acyloxy group, and more preferred are a halogen atom and an acyloxy group, and further preferred is an acyloxy group. Examples of the acyloxy group include an acetoxy group, a propionyloxy group, a butyryloxy group, an acryloyloxy group, a methacryloyloxy group, a crotonyloxy group, and the like, and an acryloyloxy group is preferable. The illustrations and preferred examples of these substituents apply to the substituents in the definitions of A ^{6 to} A ⁸ in the formula (2-3-1) described below.

More preferred are phosphoric acid esters and phosphonic acid esters, and particularly preferred are phosphoric acid esters represented by the formula (2-3-1) and phosphonic acid esters represented by the formula (2-3-2).
1-2-3-1. Phosphate ester represented by formula (2-3-1)

(Where
A ⁶ , A ⁷ and A ⁸ are each independently an alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms which may have a substituent, provided that A ^{6 to} A ⁸ At least one of them has a carbon-carbon unsaturated bond. )
Examples of the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an i-butyl group and a tert- group. Alkyl groups such as butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group and 1,2-dimethylpropyl group; vinyl Group, 1-propenyl group, 2-propenyl group (allyl group), isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, Alkenyl groups such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), 1-butynyl group, 2-butynyl Alkynyl groups such as 3-, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group; methyl group, ethyl group, n-propyl group, n-butyl group, n -A pentyl group, a vinyl group, a 2-propenyl group (allyl group), a 3-butenyl group, a 4-pentenyl group, a 2-propynyl group (propargyl group), a 3-butynyl group and a 4-pentynyl group are preferable, and a methyl group, An ethyl group, a 2-propenyl group (allyl group) and a 2-propynyl group (propargyl group) are more preferred, and a methyl group, an ethyl group and a 2-propenyl group (allyl group) are still more preferred.

Note that the substituted alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms refers to a group obtained by combining the above substituent and the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms. And preferably a 2-acryloyloxymethyl group and a 2-acryloyloxyethyl group.
Examples of the compound represented by the formula (2-3-1) include the following.

<Compound having one carbon-carbon unsaturated bond>
Compounds having a vinyl group such as dimethyl vinyl phosphate, diethyl vinyl phosphate, dipropyl vinyl phosphate, dibutyl vinyl phosphate and dipentyl vinyl phosphate;
Compounds having an allyl group such as allyl dimethyl phosphate, allyl diethyl phosphate, allyl dipropyl phosphate, allyl dibutyl phosphate and allyl dipentyl phosphate;
Compounds having a propargyl group such as propargyl dimethyl phosphate, propargyl diethyl phosphate, propargyl dipropyl phosphate, propargyl dibutyl phosphate and propargyl dipentyl phosphate;
It has a 2-acryloyloxymethyl group such as 2-acryloyloxymethyl dimethyl phosphate, 2-acryloyloxymethyl diethyl phosphate, 2-acryloyloxymethyl dipropyl phosphate, 2-acryloyloxymethyl dibutyl phosphate and 2-acryloyloxymethyl dipentyl phosphate. Compound;
It has a 2-acryloyloxyethyl group such as 2-acryloyloxyethyl dimethyl phosphate, 2-acryloyloxyethyl diethyl phosphate, 2-acryloyloxyethyl dipropyl phosphate, 2-acryloyloxyethyl dibutyl phosphate and 2-acryloyloxyethyl dipentyl phosphate. Compound;

<Compound having two carbon-carbon unsaturated bonds>
Compounds having a vinyl group such as methyl divinyl phosphate, ethyl divinyl phosphate, propyl divinyl phosphate, butyl divinyl phosphate, and pentyl divinyl phosphate;
Compounds having an allyl group such as diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl butyl phosphate and diallyl pentyl phosphate;
Compounds having a propargyl group such as dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl butyl phosphate and dipropargyl pentyl phosphate;
Bis (2-acryloyloxymethyl) methyl phosphate, bis (2-acryloyloxymethyl) ethyl phosphate, bis (2-acryloyloxymethyl) propyl phosphate, bis (2-acryloyloxymethyl) butyl phosphate and bis (2-acryloyloxy) A compound having a 2-acryloyloxymethyl group such as methyl) pentyl phosphate;
Bis (2-acryloyloxyethyl) methyl phosphate, bis (2-acryloyloxyethyl) ethyl phosphate, bis (2-acryloyloxyethyl) propyl phosphate, bis (2-acryloyloxyethyl) butyl phosphate and bis (2-acryloyloxy) A compound having a 2-acryloyloxyethyl group such as ethyl) pentyl phosphate;

<Compound having three carbon-carbon unsaturated bonds>
Trivinyl phosphate, triallyl phosphate, tripropargyl phosphate, tris (2-acryloyloxymethyl) phosphate, tris (2-acryloyloxyethyl) phosphate and the like. Are preferable, and triallyl phosphate and tris (2-acryloyloxyethyl) phosphate are more preferable.

  1-2-3-2. Phosphonic acid ester represented by formula (2-3-2)

(Where
A ⁹ , A ¹⁰ and A ¹¹ are each independently an unsubstituted or halogen-substituted alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms;
n ³² is an integer of 0 to 6. )
Examples of the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an i-butyl group and a tert- group. Alkyl groups such as butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group and 1,2-dimethylpropyl group; vinyl Group, 1-propenyl group, 2-propenyl group (allyl group), isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, Alkenyl groups such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), 1-butynyl group, 2-butynyl Alkynyl groups such as 3-, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group; methyl group, ethyl group, n-propyl group, n-butyl group, n -A pentyl group, a vinyl group, a 2-propenyl group (allyl group), a 3-butenyl group, a 4-pentenyl group, a 2-propynyl group (propargyl group), a 3-butynyl group and a 4-pentynyl group are preferable, and a methyl group, An ethyl group, a 2-propenyl group (allyl group) and a 2-propynyl group (propargyl group) are more preferred, and a methyl group, an ethyl group and a 2-propynyl group (propargyl group) are still more preferred.
Examples of the phosphonic acid ester represented by the formula (2-3-2) include the following compounds.

<Compound of Formula (2-3-2) where n ³² = 0>
Trimethyl phosphonoformate, methyl diethyl phosphonoformate, methyl dipropyl phosphonoformate, methyl dibutyl phosphonoformate, triethyl phosphonoformate, ethyl dimethyl phosphonoformate, ethyl dipropyl phosphonoformate, ethyl Dibutyl phosphonoformate, tripropyl phosphonoformate, propyl dimethyl phosphonoformate, propyl diethyl phosphonoformate, propyl dibutyl phosphonoformate, tributyl phosphonoformate, butyl dimethyl phosphonoformate, butyl diethyl phosphonoformate Noformate, butyl dipropylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, ethyl bis (2 2,2-trifluoroethyl) phosphonoacetate formate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate and the like.

<Compound of Formula (2-3-2) wherein n ³² = 1>
Trimethyl phosphonoacetate, Methyl diethyl phosphonoacetate, Methyl dipropyl phosphonoacetate, Methyl dibutyl phosphonoacetate, Triethyl phosphonoacetate, Ethyl dimethyl phosphonoacetate, Ethyl dipropyl phosphonoacetate, Ethyl dibutyl phosphonoacetate, Tripropyl Phosphonoacetate, propyl dimethyl phosphonoacetate, propyl diethyl phosphonoacetate, propyl dibutyl phosphonoacetate, tributyl phosphonoacetate, butyl dimethyl phosphonoacetate, butyl diethyl phosphonoacetate, butyl dipropyl phosphonoacetate, methyl bis (2 , 2,2-trifluoroethyl) phosphonoacetate, ethyl bis (2,2,2-trifluoroethyl) phospho Noacetate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate, allyl dimethyl phosphonoacetate, allyl diethyl phosphonoacetate, -Propynyl dimethyl phosphonoacetate, 2-propynyl diethyl phosphonoacetate and the like.

<Compound of Formula (2-3-2) wherein n ³² = 2>
Trimethyl 3-phosphonopropionate, methyl 3- (diethylphosphono) propionate, methyl 3- (dipropylphosphono) propionate, methyl 3- (dibutylphosphono) propionate, triethyl 3-phosphonopropionate, ethyl 3- (dimethylphosphono) propionate, ethyl 3- (dipropylphosphono) propionate, ethyl 3- (dibutylphosphono) propionate, tripropyl 3-phosphonopropionate, propyl 3- (dimethylphosphono) propionate, Propyl 3- (diethylphosphono) propionate, propyl 3- (dibutylphosphono) propionate, tributyl 3-phosphonopropionate, butyl 3- (dimethylphosphono) propionate, butyl 3- (diethylphosphono) propionate Pionate, butyl 3- (dipropylphosphono) propionate, methyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, ethyl 3- (bis (2,2,2-trifluoroethyl) phosphono ) Propionate, propyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, butyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate and the like.

<Compound of Formula (2-3-2) where n ³² = 3>
Trimethyl 4-phosphonobutyrate, methyl 4- (diethylphosphono) butyrate, methyl 4- (dipropylphosphono) butyrate, methyl 4- (dibutylphosphono) butyrate, triethyl 4-phosphonobutyrate, ethyl 4- (Dimethylphosphono) butyrate, ethyl 4- (dipropylphosphono) butyrate, ethyl 4- (dibutylphosphono) butyrate, tripropyl 4-phosphonobutyrate, propyl 4- (dimethylphosphono) butyrate, propyl 4- (Diethylphosphono) butyrate, propyl 4- (dibutylphosphono) butyrate, tributyl 4-phosphonobutyrate, butyl 4- (dimethylphosphono) butyrate, butyl 4- (diethylphosphono) butyrate, butyl 4- (di Propylphosphono) butyrate and the like.

Compounds of ⁿ 32 = 0, 1, 2 is preferable from the viewpoint of improving battery ^{characteristics,} the compounds of n 32 = 0, 1 are more ^{preferred, n 32} = more preferably 1 ^compounds, among the ^{n 32} = 1 compound, Compounds in which A ^{9 to} A ¹¹ are a saturated hydrocarbon group are preferred.
Particularly, trimethyl phosphonoacetate, triethyl phosphonoacetate, 2-propynyl dimethyl phosphonoacetate, and 2-propynyl diethyl phosphonoacetate are preferable.

As the phosphorus-containing organic compound, one type may be used alone, or two or more types may be used in any combination and in any ratio.
The content of the phosphorus-containing organic compound (in the case of two or more kinds, the total amount) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 100% by mass of the electrolyte solution. 0.1% by mass or more, more preferably 0.4% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably Is 3% by mass or less, more preferably 2% by mass or less, particularly preferably 1.2% by mass or less, and most preferably 0.9% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  The mass ratio of the compound represented by the above formula (1) to the phosphorus-containing organic compound can be 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10,000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, and still more preferably 100: 100 or less. : 100 or less, particularly preferably 75: 100 or less, most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-4. Organic compound having cyano group other than formula (1) The electrolytic solution of the present invention can include an organic compound having a cyano group other than formula (1). The organic compound having a cyano group other than the formula (1) is not particularly limited as long as it is an organic compound other than the formula (1) having at least one cyano group in a molecule. -4-1), compounds represented by the formulas (2-4-2) and (2-4-3), and more preferably the compounds represented by the formulas (2-4-1) and (2-4-2) ), And more preferably a compound represented by the formula (2-4-2). In addition, when the organic compound having a cyano group other than the formula (1) is also a cyclic compound having a plurality of ether bonds, the organic compound may belong to a cyclic compound having a plurality of ether bonds.

  By using the compound represented by the formula (1) in combination with an organic compound having a cyano group other than the formula (1) in the electrolytic solution of the present invention, the initial charge / discharge efficiency of the battery using the electrolytic solution is improved. While the charge / discharge efficiency after storage can be improved.

1-2-4-1. Compound A ¹ -CN (2-4-1) represented by Formula (2-4-1)
(In the formula, A ¹ represents a hydrocarbon group having 2 to 20 carbon atoms.)
The molecular weight of the compound represented by the formula (2-4-1) is not particularly limited. The molecular weight is preferably 55 or more, more preferably 65 or more, still more preferably 80 or more, and preferably 310 or less, more preferably 185 or less, and still more preferably 155 or less. Within this range, the solubility of the compound represented by the formula (2-4-1) in the non-aqueous electrolyte is easily ensured, and the effect of the present invention is easily exerted. The method for producing the compound represented by the formula (2-4-1) is not particularly limited, and the compound can be produced by arbitrarily selecting a known method.

In Formula (2-4-1), examples of the hydrocarbon group having 2 to 20 carbon atoms include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group, and an ethyl group, an n-propyl group, and an iso-propyl. Group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, tert-amyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl Alkyl group such as a group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadeci group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; vinyl group, 1-propenyl group, isopropenyl group, 1- Alkenyl groups such as butenyl and 1-pentenyl group; ethynyl group, 1-propynyl group, 1-butynyl group, 1-pentini Alkynyl groups such as phenyl group, tolyl group, ethylphenyl group, n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl And aryl groups such as a trifluoromethylphenyl group, a xylyl group, a benzyl group, a phenethyl group, a methoxyphenyl group, an ethoxyphenyl group, and a trifluoromethoxyphenyl group.

Above all, a linear or branched alkyl group having 2 to 15 carbon atoms and an alkenyl group having 2 to 4 carbon atoms are more preferable from the viewpoint that the ratio of the cyano group to the whole molecule is large and the effect of improving the battery characteristics is high. A linear or branched alkyl group having 2 to 12 carbon atoms is more preferable, and a linear or branched alkyl group having 4 to 11 carbon atoms is particularly preferable.
Examples of the compound represented by the formula (2-4-1) include propionitrile, butyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, pelargonitrile, decanenitrile, undecanenitrile, dodecanenitrile, and cyclopentanecarbonate. Nitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl -2-pentenenitrile and 2-hexenenitrile.

Among them, pentanenitrile, octanenitrile, decanenitrile, dodecanenitrile and crotononitrile are preferred from the viewpoint of stability of the compound, battery characteristics and production, pentanenitrile, decanenitrile, dodecanenitrile and crotononitrile are more preferred, Pentanenitrile, decannitrile and crotononitrile are preferred.
As the compound represented by the formula (2-4-1), one type may be used alone, or two or more types may be used in any combination and in any ratio. The amount of the compound represented by the formula (2-4-1) (in the case of two or more kinds, the total amount) can be 0.001% by mass or more in 100% by mass of the non-aqueous electrolyte solution, and is preferably. It can be 0.01% by mass or more, more preferably 0.1% by mass or more, and 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass. The content is particularly preferably 1% by mass or less, most preferably 0.5% by mass or less. Within the above range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

1-2-4-2. Compound represented by Formula (2-4-2) NC-A ² -CN (2-4-2)
(Where
A ² is an organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. . )
An organic group having 1 or more and 10 or less carbon atoms composed of at least one atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom includes carbon atoms and In addition to the organic group composed of a hydrogen atom, an organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom is included. Organic groups that may contain nitrogen, oxygen, sulfur, phosphorus, or halogen atoms may have some of the carbon atoms in the backbone of the group consisting of carbon and hydrogen atoms replaced with these atoms. Or an organic group having a substituent composed of these atoms.

The molecular weight of the compound represented by the formula (2-4-2) is not particularly limited. The molecular weight is preferably 65 or more, more preferably 80 or more, even more preferably 90 or more, and preferably 270 or less, more preferably 160 or less, and even more preferably 135 or less. Within this range, the solubility of the compound represented by the formula (2-4-2) in the nonaqueous electrolyte is easily ensured, and the effect of the present invention is easily exerted. The method for producing the compound represented by the formula (2-4-2) is not particularly limited, and the compound can be produced by arbitrarily selecting a known method.

A ² in the compound represented by the formula (2-4-2) is an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, a cycloalkenylene group or a derivative thereof. , Arylene group or derivative thereof, carbonyl group or derivative thereof, sulfonyl group or derivative thereof, sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amide group or derivative thereof, imide group or derivative thereof, ether Groups or derivatives thereof, thioether groups or derivatives thereof, borinic acid groups or derivatives thereof, borane groups or derivatives thereof, and the like.

Among them, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, and an arylene group or a derivative thereof are preferable from the viewpoint of improving battery characteristics. Further, A ² is more preferably an alkylene group having 2 to 5 carbon atoms which may have a substituent.
Examples of the compound represented by the formula (2-4-2) include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azeranitrile, sebaconitrile, undecandinitrile, dodecanenitrile, methylmalononitrile, and ethylmalononitrile. Nitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2 3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile , Bicyclohexyl-2 2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2 -Diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4 -Dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodeca , 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipropionitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like.

Of these, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azeranitrile, sebaconitrile, undecandinitrile, dodecandinitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10 -Tetraoxaspiro [5,5] undecane and fumaronitrile are preferred from the viewpoint of improving storage characteristics. Furthermore, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, glutaronitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane are The effect of improving storage characteristics is particularly excellent, and the deterioration due to side reactions in the electrode is small, and therefore it is more preferable. In general, as the molecular weight of the dinitrile compound decreases, the proportion of cyano groups in one molecule increases, and the viscosity of the molecule increases. On the other hand, as the molecular weight increases, the boiling point of the compound increases. Therefore, succinosuccinonitrile, glutaronitrile, adiponitrile, and pimeronitrile are more preferable from the viewpoint of improvement in working efficiency.

  As the compound represented by the formula (2-4-2), one type may be used alone, or two or more types may be used in optional combination and ratio. The amount of the compound represented by the formula (2-4-2) (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.1% by mass, in 100% by mass of the electrolytic solution. It is at least 01% by mass, more preferably at least 0.1% by mass, particularly preferably at least 0.3% by mass, and can be at most 10% by mass, preferably at most 5% by mass, more preferably at most 3% by mass. It is contained in a concentration of not more than mass%. When the above range is satisfied, effects such as output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

  1-2-4-3. Compound represented by formula (2-4-3)

(Where
A ³ is an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. , ^N43 is an integer of 0 or more and 5 or less. )
An organic group having 1 or more and 12 or less carbon atoms composed of at least one atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom is a carbon atom And an organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom, in addition to an organic group constituted by a hydrogen atom and a hydrogen atom. Organic groups that may contain nitrogen, oxygen, sulfur, phosphorus, or halogen atoms may have some of the carbon atoms in the backbone of the group consisting of carbon and hydrogen atoms replaced with these atoms. Or an organic group having a substituent composed of these atoms.

The above ⁿ⁴³ is an integer of 0 or more and 5 or less, preferably 0 or more and 3 or less, more preferably 0 or more and 1 or less, and particularly preferably 0.
Also, the A ³ is a hydrogen atom, a carbon atom, a nitrogen atom, it is an oxygen atom and 1 or more carbon atoms which is composed of atoms 1 to 12 organic group selected from the group consisting of sulfur atoms preferably , A hydrogen atom, a carbon atom and an oxygen atom, more preferably an organic group having 1 or more and 12 or less carbon atoms composed of one or more atoms selected from the group consisting of an oxygen atom. More preferably, it is an aliphatic hydrocarbon group having a number of 1 to 12 inclusive.

Here, the substituent means a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom.
Examples of the substituent include a halogen atom; an unsubstituted or halogen-substituted alkyl group, alkenyl group, alkynyl group, aryl group, alkoxy group; isocyanato group; alkoxycarbonyloxy group; acyl group; carboxyl group; An alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphanthryl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group, and the like, preferably a halogen atom; And more preferably a halogen atom or an unsubstituted or halogen-substituted alkyl group, and further preferably an unsubstituted alkyl group.

The aliphatic hydrocarbon group is not particularly limited, but may have 1 or more carbon atoms, preferably 2 or more, more preferably 3 or more, and 12 or less, and preferably 8 or less. Or less, more preferably 6 or less.
Examples of the aliphatic hydrocarbon group, in response to n ^43, alkanetriyl, alkanetetrayl groups, alkane pen tile group, alkanetetrayl groups, alkene tri-yl group, alkene tetrayl group, alkene pen tile group, alkene Examples include a tetrayl group, an alkynetriyl group, an alkynetetrayl group, an alkynepentile group, and an alkynetetrayl group.

Among these, a saturated hydrocarbon group such as an alkanetriyl group, an alkanetetrayl group, an alkanepentile group, and an alkanetetrayl group is more preferable, and an alkanetriyl group is more preferable.
Further, the compound represented by the formula (2-4-3) is more preferably a compound represented by the formula (2-4-3 ′).

(In the formula, A ⁴ and A ⁵ have the same meaning as A ³ above.)
Further, A ⁴ and A ⁵ are more preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent.
Examples of the hydrocarbon group include methylene, ethylene, trimethylene, tetraethylene, pentamethylene, vinylene, 1-propenylene, 2-propenylene, 1-butenylene, 2-butenylene, and 1-pentenylene. , 2-pentenylene group, ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group.

Among these, a methylene group, an ethylene group, a trimethylene group, a tetraethylene group, and a pentamethylene group are preferable, and a methylene group, an ethylene group, and a trimethylene group are more preferable.
The ^{A 4} and ^{A 5} are not identical to each other, are preferably different from.
The molecular weight of the compound represented by the formula (2-4-3) is not particularly limited. The molecular weight is preferably 90 or more, more preferably 120 or more, still more preferably 150 or more, and preferably 450 or less, more preferably 300 or less, and further preferably 250 or less. Within this range, the solubility of the compound represented by the formula (2-4-3) in the nonaqueous electrolyte is easily ensured, and the effect of the present invention is easily exerted. The method for producing the compound represented by the formula (2-4-3) is not particularly limited, and the compound can be produced by arbitrarily selecting a known method.

  Examples of the compound represented by the formula (2-4-3) include the following compounds.

  Of these,

Is preferred from the viewpoint of improving storage characteristics.
The amount of the compound represented by the formula (2-4-3) (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.1% by mass, in 100% by mass of the electrolytic solution. 01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. It is contained at a concentration of not more than 2% by mass, particularly preferably not more than 2% by mass. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

As the organic compound having a cyano group other than the formula (1), one type may be used alone, or two or more types may be used in any combination and in any ratio.
The mass ratio of the compound represented by the formula (1) to the organic compound having a cyano group other than the formula (1) is as follows: the compound represented by the formula (1): the organic compound having a cyano group other than the formula (1) Can be 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10,000: 100 or less, and preferably 500: 100 or less. : 100 or less, more preferably 300: 100 or less, still more preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. Within this range, battery characteristics, particularly initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-5. Organic Compound Having Isocyanate Group The electrolytic solution of the present invention can include an organic compound having an isocyanate group. The organic compound having an isocyanate group is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule. It is 3 or more, more preferably 2.

By using the compound represented by the formula (1) in combination with the compound having an isocyanate group in the electrolytic solution of the present invention, generation of initial gas can be suppressed in a battery using the electrolytic solution, Battery capacity can be improved.
The organic compound having an isocyanate group is preferably a linear or branched alkylene group, a cycloalkylene group, a structure in which a cycloalkylene group is linked to an alkylene group, an aromatic hydrocarbon group, an aromatic hydrocarbon group and an alkylene group. , A structure in which an ether structure (—O—), a structure in which an ether structure (—O—) is linked to an alkylene group, a carbonyl group (—C (＝ O) —), a structure in which a carbonyl group is linked to an alkylene group. , A compound in which an isocyanate group is bonded to a compound having a structure in which a sulfonyl group (—S (＝ O) —), a sulfonyl group and an alkylene group are linked, or a structure in which these are halogenated. Chain or branched alkylene group, cycloalkylene group, structure in which cycloalkylene group is linked to alkylene group, aromatic hydrocarbon Or an aromatic hydrocarbon group and an isocyanate group in a structure in which alkylene groups are linked a compound bound, more preferably a compound that the isocyanate group is bonded to a structure in which a cycloalkylene group and an alkylene group are linked. The molecular weight of the organic compound having an isocyanate group is not particularly limited. The molecular weight is preferably 80 or more, more preferably 115 or more, still more preferably 170 or more, and 300 or less, more preferably 230 or less. Within this range, it is easy to ensure the solubility of the organic compound having an isocyanate group in the non-aqueous electrolytic solution, and the effect of the present invention is easily exhibited. The method for producing the organic compound having an isocyanate group is not particularly limited, and the organic compound can be produced by arbitrarily selecting a known method. Moreover, you may use a commercial item.

Examples of the organic compound having an isocyanate group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, tert-butyl isocyanate, pentyl isocyanate hexyl isocyanate, cyclohexyl isocyanate, vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propargyl isocyanate, and phenyl Organic compounds having one isocyanate group such as isocyanate and fluorophenyl isocyanate;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanato Methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1 ′ -Diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-
4,4′-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (
Methyl isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methyl isocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, 1,5- Organic compounds having two isocyanate groups such as diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate;
And the like.

Among them, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1]
Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, Organic compounds having two isocyanate groups, such as 4,4,4-trimethylhexamethylene diisocyanate, are preferred from the viewpoint of improving storage characteristics, and hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4 , 4'-diisocyanate, bicyclo [
2.2.1] Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexa Methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate are more preferable, and 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1] are preferable. Heptane-2,5-diylbis (methylisocyanate) and bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate) are more preferred.

  The organic compound having an isocyanate group may be a trimer compound derived from a compound having at least two isocyanate groups in the molecule, or an aliphatic polyisocyanate obtained by adding a polyhydric alcohol thereto. Examples include biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of formulas (2-5-1) to (2-5-4).

(Wherein, R ^{51 to} R ⁵⁴ and R ⁵⁴ ′ are each independently a divalent hydrocarbon group (eg, a tetramethylene group or a hexamethylene group), and R ⁵³ ′ is independently a trivalent hydrocarbon group. Is a hydrocarbon group.)
The organic compound having at least two isocyanate groups in a molecule also includes a so-called blocked isocyanate which is blocked with a blocking agent to improve storage stability. Examples of the blocking agent include alcohols, phenols, organic amines, oximes, and lactams. Specifically, n-butanol, phenol, tributylamine, diethylethanolamine, methylethylketoxime, ε-caprolactam And the like.

In order to promote a reaction based on an organic compound having an isocyanate group and to obtain a higher effect, a metal catalyst such as dibutyltin dilaurate or 1,8-diazabicyclo [5.4]
. 0] It is also preferable to use an amine catalyst such as undecene-7 in combination.
As the organic compound having an isocyanate group, one type may be used alone, or two or more types may be used in optional combination and ratio.

The amount of the organic compound having an isocyanate group (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.1% by mass or more, more preferably 100% by mass in the electrolytic solution. Is at least 0.3% by mass, and can be at most 10% by mass, preferably at most 5% by mass, more preferably at most 3% by mass. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  The mass ratio of the compound represented by the above formula (1) to the organic compound having an isocyanate group can be 1: 100 or more of the compound represented by the formula (1) and the organic compound having an isocyanate group. It is preferably 10: 100 or more, more preferably 20: 100 or more, even more preferably 25: 100 or more, and can be 10,000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, The ratio is more preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-6. Silicon-containing compound The electrolytic solution of the present invention can contain a silicon-containing compound. The silicon-containing compound is not particularly limited as long as it has at least one silicon atom in the molecule. In the electrolytic solution of the present invention, by using the compound represented by the formula (1) and the silicon-containing compound in combination, it is possible to improve the initial high-rate discharge capacity and the capacity after storage.

  As the silicon-containing compound, a compound represented by the formula (2-6) is preferable.

(Where
R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, a halogen atom or a hydrocarbon group having 10 or less carbon atoms;
X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom. )
As for the hydrocarbon group, the examples and preferred examples of the hydrocarbon group in the formula (1) are applied. R ⁶¹ , R ⁶² and R ⁶³ are preferably a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an i-butyl group, a tert. -A butyl group and a phenyl group, and more preferably a methyl group.

X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, and a silicon atom, and is preferably an organic group containing at least an oxygen atom or a silicon atom. Here, an organic group refers to a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, a phosphorus atom and a halogen atom. Represent. Examples of the organic group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, a CN group, an isocyanato group, a fluoro group, an alkylsulfonic acid group, and a trialkylsilyl group. Note that a part of the monovalent organic group may be substituted with a fluorine atom. Further, the carbon number of the organic group can be 1 or more, preferably 3 or more, more preferably 5 or more, and can be 15 or less, preferably 12 or less, more preferably 8 or less. It is.

Among these, an alkylsulfonic acid group, a trialkylsilyl group, a boric acid group, a phosphoric acid group and a phosphorous acid group are preferred.
Examples of the silicon-containing compound include the following compounds.
Tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris borate (triethylsilyl), tris borate (triethoxysilyl), tris borate (dimethylvinylsilyl) and tris borate (diethylvinylsilyl) Boric acid compounds such as tris (trimethylsilyl) phosphate, tris (triethylsilyl) phosphate, tris (tripropylsilyl) phosphate, tris (triphenylsilyl) phosphate, tris (trimethoxysilyl) phosphate, phosphoric acid Phosphate compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphate, tris (dimethylvinylsilyl) phosphate and tris (diethylvinylsilyl) phosphate;

Tris phosphite (trimethylsilyl), tris phosphite (triethylsilyl), tris phosphite (tripropylsilyl), tris phosphite (triphenylsilyl), tris phosphite (trimethoxysilyl), phosphorous acid Phosphorous compounds such as tris (triethoxysilyl), tris phosphite (triphenoxysilyl), tris (dimethylvinylsilyl) phosphite and tris (diethylvinylsilyl) phosphite;
Sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate;
Hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, 1,1,2,2-tetraethyldisilane, 1,2-diphenyltetramethyldisilane and 1,1,2,2-tetraphenyl Disilane compounds such as disilane;
And the like.

  Of these, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, trimethylsilyl methanesulfonate, trimethylsilyl tetrafluoromethanesulfonate, hexamethyldisilane, hexaethyldisilane, 1,2- Diphenyltetramethyldisilane and 1,1,2,2-tetraphenyldisilane are preferred, and tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite and hexamethyldisilane are more preferred.

One of these silicon-containing compounds may be used alone, or two or more thereof may be used in any combination and in any ratio.
The silicon-containing compound (in the case of two or more kinds, the total amount) can be 0.001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass in 100% by mass of the electrolytic solution. %, And can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  The mass ratio of the compound represented by the formula (1) to the silicon-containing compound (the total amount in the case of two or more) is such that the compound represented by the formula (1): the silicon-containing compound is 1: 100 or more. And preferably at least 10: 100, more preferably at least 20: 100, even more preferably at least 25: 100 and at most 10,000: 100, preferably at most 500: 100, more preferably at most 300: 100. : 100 or less, more preferably 100: 100 or less, particularly preferably 75: 100 or less, most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-7. Aromatic compound The electrolytic solution of the present invention can contain an aromatic compound. The aromatic compound is not particularly limited as long as it is an organic compound having at least one aromatic ring in the molecule. It is an aromatic compound represented.
1-2-7-1. Aromatic compound represented by formula (2-7-1)

(In the formula, the substituent X ⁷¹ represents a halogen atom, a halogen atom, or an organic group optionally having a hetero atom. The organic group optionally having a hetero atom is a group having 1 to 12 carbon atoms. A linear, branched or cyclic saturated hydrocarbon group, a group having a carboxylic acid ester structure, a group having a carbonate structure, a group having a phosphorus atom, a group having a sulfur atom, and a group having a silicon atom are also shown. substituents may further halogen atom, a hydrocarbon group, an aromatic group, a halogen-containing hydrocarbon group may be substituted with a halogen-containing aromatic group. the number n ⁷¹ of the substituents X ⁷¹ 1 to 6 In the case of having a plurality of substituents, the respective substituents may be the same or different, and may form a ring.)
Among them, a linear, branched or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, a group having a carboxylic ester structure, and a group having a carbonate structure are preferable from the viewpoint of battery characteristics. More preferably, it is a linear, branched or cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, or a group having a carboxylic acid ester structure.

The number n ⁷¹ of the substituents X ⁷¹ is preferably 1 or more 5 or less, more preferably 1 to 3, still more preferably 1 to 2, particularly preferably 1.
X ⁷¹ represents a halogen atom, an organic group optionally having a halogen atom or a hetero atom.
Examples of the halogen atom include chlorine, fluorine and the like, and fluorine is preferred.

  Examples of the organic group having no hetero atom include a linear, branched, or cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and the linear or branched group includes those having a ring structure. It is. Specific examples of the linear, branched, or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and pentyl. Group, tert-pentyl group, cyclopentyl group, cyclohexyl group, butylcyclohexyl group, and the like. The number of carbon atoms is preferably 3 or more and 12 or less, more preferably 3 or more and 10 or less, further preferably 3 or more and 8 or less, still more preferably 3 or more and 6 or less, and most preferably 3 or more and 5 or less.

  Examples of the hetero atom constituting the organic group having a hetero atom include an oxygen atom, a sulfur atom, a phosphorus atom, and a silicon atom. Examples of the group having an oxygen atom include a group having a carboxylate ester structure and a group having a carbonate structure. Examples of those having a sulfur atom include groups having a sulfonic acid ester structure. Examples of a compound having a phosphorus atom include a group having a phosphate ester structure and a group having a phosphonate ester structure. Examples of those having a silicon atom include groups having a silicon-carbon structure.

Examples of the aromatic compound represented by the formula (2-7-1) include the following.
X ⁷¹ is a halogen atom or an organic group which may have a halogen atom, such as chlorobenzene, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride, etc. And preferred are fluorobenzene and hexafluorobenzene. More preferably, it is fluorobenzene.

^Assuming that X ⁷¹ is a hydrocarbon group having 1 to 12 carbon atoms,
2,2-diphenylpropane, 1,4-diphenylcyclohexane, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4- Phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene and the like, preferably 2,2-diphenylpropane, 1,4-diphenylcyclohexane, Cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexa , Trans-1-butyl-4-phenylcyclohexane, toluene, ethylbenzene, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene, more preferably 2,2-diphenylpropane, cyclopentylbenzene, cyclohexylbenzene, 1,1-diphenylcyclohexane, tert-butylbenzene and tert-amylbenzene, more preferably cyclohexylbenzene, tert-butylbenzene and tert-amylbenzene.

X ⁷¹ is a group having a carboxylic acid ester structure,
Phenyl acetate, benzyl acetate, 2-phenylethyl acetate, 3-phenylpropyl acetate, 4-phenylbutyl acetate, phenyl propionate, benzyl propionate, 2-phenylethyl propionate, 3-phenylpropyl propionate, 4-propionic acid Phenyl butyl, phenyl butyrate, benzyl butyrate, 2-phenylethyl butyrate, 3-phenylpropyl butyrate, 4-phenylbutyl butyrate, methyl phenylacetate, ethyl phenylacetate, propylacetate, propylacetate, butylacetate, phenylacetate, phenylacetate, benzylacetate 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, 4-phenylbutyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, ethyl 2,2-dimethyl-phenylacetate, 2,2-dimethyl-phenylacetate Propyl acetate, 2,2-dimethyl-phenyl acetate butyl, 2,2-dimethyl-phenyl acetate, 2,2-dimethyl-benzyl acetate, 2,2-dimethyl-phenyl acetate 2-phenylethyl, 2,2 -Dimethyl-phenylacetate 3-phenylpropyl, 2,2-dimethyl-phenylacetate 4-phenylbutyl, methyl 3-phenylpropionate, ethyl 3-phenylpropionate, propyl 3-phenylpropionate, butyl 3-phenylpropionate Phenyl 3-phenylpropionate, benzyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, 4-phenylbutyl 3-phenylpropionate, methyl 4-phenylbutyrate , 4-phenylbutyric acid Propyl 4-phenylbutyrate, butyl 4-phenylbutyrate, phenyl 4-phenylbutyrate, benzyl 4-phenylbutyrate, 2-phenylethyl 4-phenylbutyrate, 3-phenylpropyl 4-phenylbutyrate, 4-phenyl 4-phenylbutyrate Butyl, methyl 5-phenylvalerate, ethyl 5-phenylvalerate, propyl 5-phenylvalerate, butyl 5-phenylvalerate, phenyl 5-phenylvalerate, benzyl 5-phenylvalerate, 5-phenylvaleric acid 2 -Phenylethyl, 3-phenylpropyl 5-phenylvalerate, 4-phenylbutyl 5-phenylvalerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, propyl 1-phenylcyclopentanecarboxylate , 1-phenylcyclopentanecarboxylic acid butyrate Phenyl, 1-phenylcyclopentanecarboxylate, benzyl 1-phenylcyclopentanecarboxylate, 2-phenylethyl 1-phenylcyclopentanecarboxylate, 3-phenylpropyl 1-phenylcyclopentanecarboxylate, 1-phenylcyclopentanecarboxylate 4-phenylbutyl acid, 2,2-bis (4-acetoxyphenyl) propane and the like, and preferably 2-phenylethyl acetate, 3-phenylpropyl acetate, 4-phenylbutyl acetate, 2-phenylethyl propionate 3-phenylpropyl propionate, 4-phenylbutyl propionate, 2-phenylethyl butyrate, 3-phenylpropyl butyrate, 4-phenylbutyl butyrate, methyl phenylacetate, ethyl phenylacetate, phenylacetate propyl, phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, 4-phenylbutyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, ethyl 2,2-dimethyl-phenylacetate, propyl 2,2-dimethyl-phenylacetate 2,2-dimethyl-phenyl acetate, 2-phenylethyl 2,2-dimethyl-phenyl acetate, 3-phenylpropyl 2,2-dimethyl-phenyl acetate, 4-phenylbutyl 2,2-dimethyl-phenyl acetate, Methyl 3-phenylpropionate, ethyl 3-phenylpropionate, propyl 3-phenylpropionate, butyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, 3- 4-phenylbutyl phenylpropionate Methyl 4-phenylbutyrate, ethyl 4-phenylbutyrate, propyl 4-phenylbutyrate, butyl 4-phenylbutyrate, 2-phenylethyl 4-phenylbutyrate, 3-phenylpropyl 4-phenylbutyrate, 4-phenylbutyl 4-phenylbutyrate Methyl 5-phenyl valerate, ethyl 5-phenyl valerate, propyl 5-phenyl valerate, butyl 5-phenyl valerate, 2-phenyl ethyl 5-phenyl valerate, 3-phenyl propyl 5-phenyl valerate, 5 4-phenylbutyl phenylvalerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, propyl 1-phenylcyclopentanecarboxylate, butyl 1-phenylcyclopentanecarboxylate, 1-phenylcyclopentane 2-phenylethyl carboxylate, 1 3-phenylpropyl phenylcyclopentanecarboxylate, more preferably 2-phenylethyl acetate, 3-phenylpropyl acetate, methyl phenylacetate, ethyl phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate Methyl 2,2-dimethyl-phenylacetate, ethyl 2,2-dimethyl-phenylacetate, 2-phenylethyl 2,2-dimethyl-phenylacetate, 3-phenylpropyl 2,2-dimethyl-phenylacetate, 3-phenylpropyl Methyl onate, ethyl 3-phenylpropionate, 2-phenylethyl 3-phenylpropionate, 3-phenylpropyl 3-phenylpropionate, methyl 5-phenylvalerate, ethyl 5-phenylvalerate, 5-phenylvalerate 2-phenylethyl, 5-phenyl 3-phenylpropyl valerate, methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, 2-phenylethyl 1-phenylcyclopentanecarboxylate, 3-phenylpropyl 1-phenylcyclopentanecarboxylate More preferably, 2-phenylethyl acetate, 3-phenylpropyl acetate, methyl phenylacetate, ethyl phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, methyl 2,2-dimethyl-phenylacetate, 2,2-dimethyl-phenylacetate, 2-phenylethyl 2,2-dimethyl-phenylacetate, 3-phenylpropyl 2,2-dimethyl-phenylacetate, methyl 3-phenylpropionate, ethyl 3-phenylpropionate, 3-phenyl 2-phenylethyl lopionate, 3-phenylpropyl 3-phenylpropionate, methyl 5-phenylvalerate, ethyl 5-phenylvalerate, 2-phenylethyl 5-phenylvalerate, 3-phenylpropyl 5-phenylvalerate , Methyl 1-phenylcyclopentanecarboxylate, ethyl 1-phenylcyclopentanecarboxylate, 2-phenylethyl 1-phenylcyclopentanecarboxylate, and 3-phenylpropyl 1-phenylcyclopentanecarboxylate.

X ⁷¹ is a group having a carbonate structure,
2,2-bis (4-methoxycarbonyloxyphenyl) propane, 1,1-bis (4-methoxycarbonyloxyphenyl) cyclohexane, diphenyl carbonate, methylphenyl carbonate, ethylphenyl carbonate, 2-tert-butylphenylmethyl carbonate, 2-tert-butylphenylethyl carbonate, bis (2-tert-butylphenyl) carbonate, 4-tert-butylphenylmethyl carbonate, 4-tert-butylphenylethyl carbonate, bis (4-tert-butylphenyl) carbonate, benzyl Methyl carbonate, benzyl ethyl carbonate, dibenzyl carbonate and the like, and preferably 2,2-bis (4-methoxycarbonyloxyphenyl) propane, , 1,1-bis (4-methoxycarbonyloxyphenyl) cyclohexane body, diphenyl carbonate, methyl phenyl carbonate, more preferably diphenyl carbonate, methyl phenyl carbonate, more preferably methyl phenyl carbonate.

X ⁷¹ is a group having a sulfonic acid ester structure,
Methylphenylsulfonate, ethylphenylsulfonate, diphenylsulfonate, phenylmethylsulfonate, 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate, cyclohexylphenylmethylsulfonate and the like, preferably methylphenylsulfonate, diphenylsulfonate 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate and cyclohexylphenylmethylsulfonate, more preferably methylphenylsulfonate, 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate And cyclohexylphenylmethylsulfonate.

X ⁷¹ is a group having a silicon-carbon structure,
Examples include trimethylphenylsilane, diphenylsilane, diphenyltetramethyldisilane, and the like, with trimethylphenylsilane being preferred.
X ⁷¹ is a group having a phosphate ester structure,
Triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylphenyl) phosphate, tris (4-tert-butylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris ( 3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2-cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, diethyl (4 -Methylbenzyl) phosphonate and the like, preferably triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylphenyl). ) Phosphate, tris (4-tert-amylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris (3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2 -Cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate and tris (4-cyclohexylphenyl) phosphate, more preferably tris (2-tert-butylphenyl) phosphate and tris (4-tert-butylphenyl) Phosphate, tris (2-cyclohexylphenyl) phosphate and tris (4-cyclohexylphenyl) phosphate.

X ⁷¹ is a group having a phosphonate ester structure,
Dimethylphenylphosphonate, diethylphenylphosphonate, methylphenylphenylphosphonate, ethylphenylphenylphosphonate, diphenylphenylphosphonate, dimethyl- (4-fluorophenyl) -phosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, methylphenylbenzylphosphonate, ethylphenylbenzylphosphonate , Diphenylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate, diethyl- (4-fluorobenzyl) phosphonate, and the like, preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethyl- (4-fluorophenyl) -phosphonate, Dimethylbenzylphosphonate, diethylbenzylphosphonate, Tyl- (4-fluorobenzyl) phosphonate and diethyl- (4-fluorobenzyl) phosphonate, more preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate , Diethyl- (4-fluorobenzyl) phosphonate.

Further, the aromatic compound represented by the formula (2-7-1) also includes a fluorinated product of the above aromatic compound. In particular,
Partially fluorinated products of those having a hydrocarbon group such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, trifluoromethylbenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; Partially fluorinated compounds having a carboxylic acid ester structure such as fluorophenyl acetate and 4-fluorophenyl acetate; trifluoromethoxybenzene, 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, And partially fluorinated products having an ether structure such as 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole, and 4-trifluoromethoxyanisole. Preferably, a partially fluorinated product of a compound having a hydrocarbon group such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, o-cyclohexylfluorobenzene, or p-cyclohexylfluorobenzene; 2-fluorophenyl acetate Fluorinated compounds having a carboxylic acid ester structure such as 4-fluorophenylacetate; ether structures such as trifluoromethoxybenzene 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole and 4-trifluoromethoxyanisole 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, and the like, more preferably a partially fluorinated product of a compound having a hydrocarbon group such as 2-fluorotoluene, 3-fluorotoluene, and 4-fluorotoluene; Partially fluorinated products having a carboxylic acid ester structure such as phenylacetate and 4-fluorophenylacetate; trifluoromethoxybenzene, 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 4-trifluoromethoxyanisole and the like And partially fluorinated compounds having an ether structure of

  1-2-7-2. Aromatic compound represented by formula (2-7-2)

(Wherein, R ^{11 to} R ¹⁵ are each independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, and R ¹⁶ and R ¹⁷ are each independently a carbon atom. A hydrocarbon group having a number of 1 or more and 12 or less, and at least two of R ^{11 to} R ¹⁷ may form a ring together, provided that the formula (2-7-2) is represented by the formula (A) And (B):
(A) at least one of R ^{11 to} R ¹⁵ is halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms;
(B) The total number of carbon atoms of R ^{11 to} R ¹⁷ is 3 or more and 20 or less, and at least one of the conditions is satisfied)
Is an aromatic compound represented by If at least two of R ¹¹ to R ¹⁷ but that together form a ^ring, it is preferred that two of R 11 ^{to R 17} form a ring together.

R ¹⁶ and R ¹⁷ are each independently a hydrocarbon group having 1 to 12 carbon atoms (eg, an alkyl group or an aryl group), and R ¹⁶ and R ¹⁷ are taken together to form a ring (eg, a hydrocarbon group) May be formed. From the viewpoints of improving the initial efficiency, solubility and storage characteristics, R ¹⁶ and R ¹⁷ are preferably a hydrocarbon group having 1 to 12 carbon atoms, or a hydrocarbon formed by combining R ¹⁶ and R ^17. A cyclic group, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, or a hydrocarbon group formed by R ¹⁶ and R ¹⁷ together. To an 8-membered cyclic group, more preferably a methyl group, an ethyl group, a cyclohexyl group or a cyclopentyl group formed by R ¹⁶ and R ¹⁷ together, most preferably a methyl group, an ethyl group, ¹⁶ and R ¹⁷ are a cyclohexyl group formed together.

R ^{11 to} R ¹⁵ are each independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (eg, an alkyl group, an aryl group, or an aralkyl group). They may together form a ring (eg, a cyclic group that is a hydrocarbon group). From the viewpoint of improving the initial efficiency and solubility and storage characteristics, hydrogen, fluorine, unsubstituted or halogen-substituted hydrocarbon groups having 1 to 12 carbon atoms, more preferably hydrogen, fluorine, unsubstituted or substituted with fluorine. A hydrocarbon group having 1 to 10 carbon atoms, more preferably hydrogen, fluorine, tert-butyl group, tert-pentyl group, tert-hexyl group, tert-heptyl group, methyl group, ethyl group, propyl group, A butyl group, a trifluoromethyl group, a nonafluorotert-butyl group, a 1-methyl-1-phenyl-ethyl group, a 1-ethyl-1-phenyl-propyl group, and particularly preferably hydrogen, fluorine, and a tert-butyl group; 1-methyl-1-phenyl-ethyl group, most preferably hydrogen, tert-butyl group, 1-methyl-1- Eniru - an ethyl group.

Any one of R ^{11 to} R ¹⁵ and R ¹⁶ may be combined to form a ring (for example, a cyclic group that is a hydrocarbon group). Preferably, R ¹¹ and R ¹⁶ together form a ring (eg, a cyclic group that is a hydrocarbon group). In this case, R ¹⁷ is preferably an alkyl group. Examples of compounds in which R ¹⁷ is a methyl group and R ¹¹ and R ¹⁶ together form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like.

The formula (2-7-2) is obtained from (A) and (B):
(A) at least one of R ^{11 to} R ¹⁵ is halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms;
(B) the total number of carbon atoms of R ^{11 to} R ¹⁷ is 3 or more and 20 or less;
At least one of the conditions is satisfied.

Formula (2-7-2) preferably satisfies (A) from the viewpoint of suppressing oxidation on the positive electrode within a normal battery operating voltage range, and from the viewpoint of solubility in an electrolytic solution, Preferably, B) is satisfied. Formula (2-7-2) may satisfy both (A) and (B).
Regarding (A), if at least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, a ring is formed even if the other is a hydrogen atom. You may have. From the viewpoint of solubility in the electrolytic solution, the number of carbon atoms of the unsubstituted or halogen-substituted hydrocarbon group is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less, still more preferably 1 or more and 3 or less, even more preferably. 1 or 2, most preferably 1.

With regard to (B), as long as the total number of carbon atoms of R ^{11 to} R ¹⁷ is 3 or more and 20 or less, at least two of R ^{11 to} R ¹⁷ may form a ring together. When at least two of R ^{11 to} R ¹⁷ together form a ring, when calculating the total number of carbon atoms, the carbon (R) which does not correspond to R ^{11 to} R ¹⁷ among the carbon atoms forming the ring for ¹¹ to R ^15, carbon atoms constituting the benzene ring to which they are ^attached, for ^{R 16} and ^{R 17,} carbon atoms in the benzyl position) is set to be not counted. The total number of carbon atoms is preferably 3 or more and 14 or less, more preferably 3 or more and 10 or less from the viewpoint of solubility in the electrolytic solution. For example, as a compound in which R ¹⁷ is a methyl group and R ¹¹ and R ¹⁶ together form a ring, 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl -1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like, which satisfy the condition (B).

Examples of the aromatic compound represented by the formula (2-7-2) include the following.
R ¹⁶ and R ¹⁷ are each independently a hydrocarbon group having 1 to 20 carbon atoms (however, the total of R ¹⁶ and R ¹⁷ is 3 to 20 carbon atoms), and R ^{11 to} R ¹⁵ are A compound that is hydrogen (fills (B)).
2,2-diphenylbutane, 3,3-diphenylpentane, 3,3-diphenylhexane, 4,4-diphenylheptane, 5,5-diphenyloctane, 6,6-diphenylnonane, 1,1-diphenyl-1, 1-ditert-butyl-methane.

A compound in which R ¹⁶ and R ¹⁷ together form a ring, and R ^{11 to} R ¹⁵ are hydrogen (filling (B)).
1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1-diphenyl-4-methylcyclohexane.
The following compounds may be used (these compounds may overlap with the above-mentioned compounds, but are represented by the structural formula).

A compound in which at least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (fills (A)).
1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene.
The following compounds may be used (these compounds may overlap with the above-mentioned compounds, but are represented by the structural formula).

R ¹⁷ is a hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group having 1 to 20 carbon atoms, preferably a methyl group), and R ¹¹ and R ¹⁶ together form a ring Compound (satisfies (B)).
1-phenyl-1,3,3-trimethylindane.
The following compounds may be used (these compounds may overlap with the above-mentioned compounds, but are represented by the structural formula).

Among them, preferred from the viewpoint of the reducibility on the initial negative electrode,
2,2-diphenylbutane, 3,3-diphenylpentane, 1,1-diphenyl-1,1-ditert-butyl-methane, 1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1- Diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl-1,3 , 3-trimethylindane.

  The following compounds are also preferred (these compounds may overlap with the above preferred compounds, but are represented by the structural formula).

More preferred is
2,2-diphenylbutane, 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1 -Methyl-1-phenylethyl) -benzene and 1-phenyl-1,3,3-trimethylindane.
The following compounds are also preferred (there may be overlaps with the more preferred compounds described above, but they are represented by the structural formula).

More preferred are 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, and 1,4-bis (1-methyl-hexane). 1-phenylethyl) -benzene and 1-phenyl-1,3,3-trimethylindane.
The following compounds are also more preferable (these compounds may overlap with the above more preferable compounds, but are represented by the structural formula).

  Particularly preferred are 1,1-diphenylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl -1,3,3-trimethylindane, represented by the following structural formula.

Most preferably, it is a 1-phenyl-1,3,3-trimethylindane compound, represented by the following structural formula.

The aromatic compounds may be used alone or in combination of two or more. In the total amount of the nonaqueous electrolyte (100% by mass), the amount of the aromatic compound (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, It is more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, further preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less. , More preferably 5% by mass or less, further preferably 3% by mass or less, particularly preferably 2.5% by mass or less. When the content is within the above range, the effects of the present invention can be easily exhibited, and an increase in battery resistance can be prevented.

  The mass ratio of the compound represented by the formula (1) to the aromatic compound (the total amount in the case of two or more) is such that the compound represented by the formula (1): the aromatic compound is 1: 100 or more. And preferably at least 10: 100, more preferably at least 20: 100, even more preferably at least 25: 100 and at most 10,000: 100, preferably at most 500: 100, more preferably at most 300: 100. : 100 or less, more preferably 100: 100 or less, particularly preferably 75: 100 or less, most preferably 50: 100 or less. Within this range, the overcharge characteristics can be improved without lowering the battery characteristics.

1-2-8. As a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter sometimes referred to as “unsaturated cyclic carbonate”) may be a carbon-carbon double bond or a carbon-carbon triple bond. There is no particular limitation as long as the cyclic carbonate has a bond, and any unsaturated carbonate can be used. Note that a cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

As unsaturated cyclic carbonates, vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, Catechol carbonates and the like.
Examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinyl vinylene carbonate, 4,5-divinylvinylene carbonate, allyl vinylene carbonate, , 5-Diallylvinylene carbonate, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluoro Vinylene carbonate and the like.

Specific examples of the ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, and 4-methyl-5-carbonate. Vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl -5-ethynylethylene carbonate,
Phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5 Allyl ethylene carbonate and the like can be mentioned.

  Among them, particularly preferred unsaturated cyclic carbonates to be used in combination are vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5- Diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4- Allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4- -5-ethynyl ethylene carbonate. Further, vinylene carbonate, vinyl ethylene carbonate and ethynyl ethylene carbonate are preferred because they form a more stable interfacial protective film, and vinylene carbonate and vinyl ethylene carbonate are more preferred.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more, more preferably 85 or more, and is preferably 250 or less, more preferably 150 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolytic solution can be easily ensured, and the effect of the present invention can be sufficiently exhibited.

The method for producing the unsaturated cyclic carbonate is not particularly limited, and it is possible to arbitrarily select and produce a known method.
As the unsaturated cyclic carbonate, one type may be used alone, or two or more types may be used in optional combination and ratio. The amount of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The compounding amount of the unsaturated cyclic carbonate can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, in 100% by mass of the nonaqueous electrolyte. It is preferably 0.5% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, particularly preferably 2% by mass or less. % By mass or less. Within this range, the non-aqueous electrolyte secondary battery can easily exhibit a sufficient effect of improving the cycle characteristics, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity retention ratio is reduced. It is easy to avoid the situation.

  The mass ratio of the compound represented by the formula (1) to the cyclic carbonate having a carbon-carbon unsaturated bond (the total amount in the case of two or more) is the compound represented by the formula (1): carbon-carbon unsaturated bond. The cyclic carbonate having a saturated bond can be 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and 10,000: 100 or less. It is preferably 500: 100 or less, more preferably 300: 100 or less, further preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-9. Fluorine-free carboxylic acid ester The electrolytic solution of the present invention can contain a fluorine-free carboxylic acid ester. By using the compound represented by the formula (1) and the fluorine-free carboxylic acid ester together in the electrolytic solution of the present invention, the high-temperature storage characteristics of the battery can be improved. The fluorine-free carboxylic acid ester is not particularly limited as long as it is a carboxylic acid ester having no fluorine atom in a molecule, but is preferably a fluorine-free chain carboxylic acid ester, and more preferably a fluorine-free carboxylic acid ester. It is a saturated chain carboxylic acid ester. The total carbon number of the fluorine-free chain carboxylic acid ester is preferably 3 or more, more preferably 4 or more, still more preferably 5 or more, preferably 7 or less, more preferably 6 or less, and still more preferably 5 or less. It is.

Examples of the fluorine-free chain carboxylic acid ester include the following.
Methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, -tert-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-propionate Butyl, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, isobutyl butyrate, tert-butyl butyrate, methyl isobutyrate, ethyl isobutyrate, iso N-propyl butyrate, isopropyl isobutyrate, n-butyl isobutyrate, isobutyl isobutyrate, tert-butyl isobutyrate, methyl valerate, ethyl valerate, n-propyl valerate, isopropyl valerate, n-butyl valerate, Isobutyl valerate, valeric acid-ter -Butyl, methyl hydroangelica, ethyl hydroangelica, n-propyl hydroangelica, isopropyl hydroangelica, n-butyl hydroangelica, isobutyl hydroangelica, tert-butyl hydroangelica, methyl isovalerate, Ethyl isovalerate, n-propyl isovalerate, isopropyl isovalerate, n-butyl isovalerate, isobutyl isovalerate, tert-butyl isovalerate, methyl pivalate, ethyl pivalate, n-propyl pivalate Saturated chain carboxylic acid esters such as isopropyl pivalate, n-butyl pivalate, isobutyl pivalate, and tert-butyl pivalate;

Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacryl Isopropyl acrylate, n-butyl methacrylate, isobutyl methacrylate, -tert-butyl methacrylate, methyl crotonate, ethyl crotonate, n-propyl crotonate, isopropyl crotonate, n-butyl crotonate, isobutyl crotonate, crotonic acid -Tert-butyl, methyl 3-butenoate, ethyl 3-butenoate, n-propyl 3-butenoate, isopropyl 3-butenoate, n-butyl 3-butenoate, isobutyl 3-butenoate, 3-butenoic acid- tert-butyl, 4-pe Methyl formate, ethyl 4-pentenoate, n-propyl 4-pentenoate, isopropyl 4-pentenoate, n-butyl 4-pentenoate, isobutyl 4-pentenoate, tert-butyl 4-pentenoate, 3-pentene Methyl pentate, ethyl 3-pentenoate, n-propyl 3-pentenoate, isopropyl 3-pentenoate, n-butyl 3-pentenoate, isobutyl 3-pentenoate, tert-butyl 3-pentenoate, 2-pentenoic acid Methyl, ethyl 2-pentenoate, n-propyl 2-pentenoate, isopropyl 2-pentenoate, n-butyl 2-pentenoate, isobutyl 2-pentenoate, tert-butyl 2-pentenoate, methyl 2-propanoate , Ethyl 2-propinate, n-propyl 2-propinate, isopropyl 2-propinate, 2-propynate -Butyl, isobutyl 2-propinate, -tert-butyl 2-propinate, methyl 3-butyrate, ethyl 3-butyrate, n-propyl 3-butyrate, isopropyl 3-butyrate, n-butyric acid Butyl, isobutyl 3-butyrate, tert-butyl 3-butyrate, methyl 2-butyrate, ethyl 2-butyrate, n-propyl 2-butyrate, isopropyl 2-butyrate, n-butyl 2-butyrate Isobutyl 2-butyrate, tert-butyl 2-butyrate, methyl 4-pentate, ethyl 4-pentate, n-propyl 4-pentate, isopropyl 4-pentate, n-butyl 4-pentate, Isobutyl 4-pentynate, 4-pentylic acid-te
rt-butyl, methyl 3-pentate, ethyl 3-pentate, n-propyl 3-pentate, isopropyl 3-pentate, n-butyl 3-pentate, isobutyl 3-pentate, 3-tert-pentate -Butyl, methyl 2-pentate, ethyl 2-pentate, n-propyl 2-pentate, isopropyl 2-pentate, n-butyl 2-pentate, isobutyl 2-pentate, -tert- 2-pentate Unsaturated carboxylic acid esters such as butyl.

  Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, n-butyl propionate, from the viewpoint of less side reactions at the negative electrode, Methyl butyrate, ethyl butyrate, n-propyl butyrate, n-butyl butyrate, methyl valerate, ethyl valerate, n-propyl valerate, n-butyl valerate, methyl pivalate, ethyl pivalate, n-propyl pivalate, Preferred is n-butyl pivalate, and from the viewpoint of improving ionic conductivity due to a decrease in the viscosity of the electrolyte solution, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, and n-propionate -Propyl and n-butyl propionate are more preferred, and methyl propionate, ethyl propionate and propionic acid - propyl, n- butyl propionate are more preferable, and ethyl propionate, propionic acid n- propyl particularly preferred.

As the fluorine-free carboxylic acid ester, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
The amount of the fluorine-free carboxylic acid ester (in the case of two or more kinds, the total amount) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 100% by mass in the electrolytic solution. Is 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, It is more preferably at most 3% by mass, further preferably at most 2% by mass, particularly preferably at most 1% by mass. In addition, when the fluorine-free carboxylic acid ester is used as the non-aqueous solvent, the compounding amount is preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. , Even more preferably at least 20% by volume and at most 50% by volume, more preferably at most 45% by volume, even more preferably at most 40% by volume. Within such a range, an increase in negative electrode resistance is suppressed, and output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, and high-temperature storage characteristics are easily controlled.

  The mass ratio of the compound represented by the formula (1) and the fluorine-free carboxylic acid ester can be 1: 100 or more of the compound represented by the formula (1): the fluorine-free carboxylic acid ester, It is preferably 10: 100 or more, more preferably 20: 100 or more, even more preferably 25: 100 or more, and can be 10,000: 100 or less, preferably 500: 100 or less, more preferably 300: 100 or less, The ratio is more preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-2-10. Cyclic compound having a plurality of ether bonds The cyclic compound having a plurality of ether bonds is not particularly limited as long as it is a cyclic compound having a plurality of ether bonds in a molecule, but is preferably represented by the formula (2-10). Compound. The cyclic compound having a plurality of ether bonds contributes to the improvement of the high-temperature storage characteristics of the battery. In the electrolytic solution of the present invention, by using the compound represented by the formula (1) in combination, a good initial Properties can be retained.

(Where
A ^{15 to} A ²⁰ independently represent a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent. n ¹⁰¹ is an integer of 1 or more and 4 or less, and when n ¹⁰¹ is an integer of 2 or more, a plurality of A ¹⁷ and A ¹⁸ may be the same or different. )
Note that two members selected from A ^{15 to} A ²⁰ may be bonded to each other to form a ring. In this case, it is preferable that A ¹⁷ and A ¹⁸ form a ring structure. Further, the total number of carbon atoms of A ^{15 to} A ²⁰ is preferably 0 or more and 8 or less, more preferably 0 or more and 4 or less, further preferably 0 or more and 2 or less, and particularly preferably 0 or more and 1 or less.

  As a substituent, a halogen atom, which may be substituted with a fluorine atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, and a cyano group, an isocyanato group, an ether group, a carbonate group, a carbonyl group, Examples thereof include a carboxy group, an alkoxycarbonyl group, an acyloxy group, a sulfonyl group, a phosphanthryl group, and a phosphoryl group. Of these, preferably an alkyl group, an alkenyl group, an alkynyl group which may be substituted with a halogen atom, an alkoxy group or a fluorine atom, and an isocyanato group, a cyano group, an ether group, a carbonyl group, an alkoxycarbonyl group, an acyloxy group And more preferably an alkyl group not substituted with a fluorine atom, a cyano group and an ether group.

In Formula (2-10), n ¹⁰¹ is preferably an integer of 1 or more and 3 or less, more preferably an integer of 1 or more and 2 or less, and further preferably n ¹⁰¹ is 2.
Examples of the hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ include a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, and an aryl group;
Divalent hydrocarbon groups such as an alkylene group, alkenylene group, alkynylene group and arylene group; and the like. Among these, an alkyl group and an alkylene group are preferred, and an alkyl group is more preferred. As a specific example,
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl An alkyl group having 1 to 5 carbon atoms such as a group, a 1-methylbutyl group, a 2-methylbutyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group;
Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl An alkenyl group having 2 to 5 carbon atoms, such as a group;

Carbon such as ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group, etc. An alkynyl group of 2 to 5;
Alkylene groups having 1 to 5 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group; vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group Alkenylene groups having 2 to 5 carbon atoms, such as, 1-pentenylene and 2-pentenylene;

Examples thereof include an alkynylene group having 2 to 5 carbon atoms, such as an ethynylene group, a propynylene group, a 1-butynylene group, a 2-butynylene group, a 1-pentynylene group, and a 2-pentynylene group. Of these, preferred are alkylene groups having 1 to 5 carbon atoms such as methylene, ethylene, trimethylene, tetramethylene, and pentamethylene, and more preferred are ethylene, trimethylene, tetramethylene, and pentamethylene. An alkylene group having 2 to 5 carbon atoms such as a methylene group, and more preferably an alkylene group having 3 to 5 carbon atoms such as a trimethylene group, a tetramethylene group, and a pentamethylene group.

A hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ refers to a group obtained by combining a hydrogen atom, a fluorine atom or the above substituent and the above hydrocarbon group having 1 to 5 carbon atoms. Preferably represents a hydrogen atom, an unsubstituted hydrocarbon group having 1 to 5 carbon atoms and an alkylene group having an ether structure in which part of the carbon chain of the alkylene group is substituted with an ether group. And more preferably a hydrogen atom.

  Examples of the cyclic compound having a plurality of ether bonds include the following compounds.

  Among them,

Are preferred.

Is more preferred.
As the cyclic compound having a plurality of ether bonds, one kind may be used alone, and two kinds or more may be used in optional combination and ratio. The amount of the cyclic compound having a plurality of ether bonds (in the case of two or more kinds, the total amount) can be 0.001% by mass or more, preferably 0.01% by mass or more in 100% by mass of the electrolytic solution. It is more preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, furthermore It is preferably at most 2% by mass. When the above range is satisfied, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

  The mass ratio of the compound represented by the above formula (1) and the cyclic compound having a plurality of ether bonds (the total amount in the case of two or more) is a compound represented by the formula (1): having a plurality of ether bonds. The cyclic compound can be 1: 100 or more, preferably 10: 100 or more, more preferably 20: 100 or more, still more preferably 25: 100 or more, and can be 10000: 100 or less, preferably Is 500: 100 or less, more preferably 300: 100 or less, further preferably 100: 100 or less, particularly preferably 75: 100 or less, and most preferably 50: 100 or less. Within this range, battery characteristics, especially initial characteristics, can be significantly improved. It is not clear about this principle, but it is considered that by mixing at this ratio, the side reaction of the additive on the electrode can be minimized.

1-3. Electrolyte The electrolyte is not particularly limited, and any known electrolyte can be used. In the case of a lithium secondary battery, a lithium salt is usually used. Specifically, inorganic lithium salts such as LiPF ₆ , LiBF _4, LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ and LiWF ₇ ; lithium tungstates such as LiWOF ₅ ; HCO ₂ Li, CH ₃ CO ₂ Li; CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ Lithium carboxylate such as CF ₂ CO ₂ Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF _{3 CF 2 CF 2 SO 3 Li,} CF 3 CF 2 CF 2 CF 2 SO 3 sulfonate lithium salt such as Li _{; LiN (FCO) 2, LiN} (FCO) (FSO 2), LiN (FSO 2) 2, LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, lithium imide such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) Salts; Lithium methide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ and LiC (C ₂ F ₅ SO ₂ ) ₃ ; Lithium such as lithium bis (malonato) borate and lithium difluoro (malonato) borate Malonato) borate salts; lithium tris (malonato) phosphate, lithium difluorobis (malonato) Sufeto, lithium (Maronato) phosphate salts such as lithium tetrafluoro (Maronato) phosphate; _{other, LiPF 4 (CF 3) 2} , LiPF 4 (C 2 F 5) 2, LiPF 4 (CF 3 SO 2) 2, LiPF 4 (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ ( Fluorinated organic lithium salts such as CF ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; lithium oxalato borates such as lithium difluorooxalato borate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, and lithium tris (oxalato) phosphate; and the like.

Among _{them, LiPF 6, LiSbF 6, LiTaF} 6, FSO 3 Li, CF 3 SO 3 Li, LiN (FSO 2) 2, LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN _{(C 2 F 5 SO 2)} 2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiC (FSO 2) 3,} LiC (CF 3 SO 2) _{3, LiC (C 2 F 5} SO 2) 3, LiBF 3 CF 3, LiBF 3 C 2 F 5, LiPF 3 (CF 3) 3, LiPF 3 (C 2 F 5) 3, lithium difluoro oxalatoborate, lithium Bis (oxalato) borate, lithium difluorobis (oxalato) phosphate, etc. have output characteristics and Rate charge and discharge characteristics, high-temperature storage characteristics, particularly preferred from the viewpoint that an effect of improving the cycle characteristics and the like.

  The concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range to ensure good battery performance. From the viewpoint, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and still more preferably 0.5 mol / L or more. Is at most 3 mol / L, more preferably at most 2.5 mol / L, even more preferably at most 2.0 mol / L. In this range, the amount of lithium as charged particles is not too small, and the viscosity can be set in an appropriate range, so that it is easy to secure good electric conductivity.

When two or more electrolytes are used in combination, at least one of them is preferably a salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate, and fluorosulfonate. Furthermore, it is more preferable that the salt is selected from the group consisting of monofluorophosphate, difluorophosphate, oxalate and fluorosulfonate. Of these, lithium salts are preferred. The salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate can be 0.01% by mass or more, preferably 0.1% by mass. %, And can be 20% by mass or less, preferably 10% by mass or less.

The electrolyte preferably contains one or more selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate, and one or more other salts. . Other salts include the lithium salts exemplified above, and in particular, LiPF ₆ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) ₃ are preferable, and LiPF ₆ is more preferable. Other salts may be 0.01% by mass or more, preferably 0.1% by mass or more, and 20% by mass or more from the viewpoint of ensuring an appropriate balance between the conductivity and the viscosity of the electrolytic solution. Or less, preferably 15% by mass or less, more preferably 10% by mass or less.

  The total amount of the electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and still more preferably 0.5 mol / L or more in the non-aqueous electrolyte, from the viewpoint of ensuring good battery performance. And preferably 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less, particularly preferably 1.5 mol / L or less.

1-3-1. Monofluorophosphate and difluorophosphate Monofluorophosphate and difluorophosphate are not particularly limited as long as they each have at least one monofluorophosphate or difluorophosphate structure in the molecule. In the electrolytic solution of the present invention, the compound represented by the above formula (1) is used in combination with at least one selected from monofluorophosphates and difluorophosphates, whereby the volume change after the initial charge / discharge of the battery. Can be significantly suppressed, and the safety at the time of overcharge can be further improved. In addition, the combined use can reduce the initial irreversible capacity of the battery and improve the discharge storage characteristics. At the same time, the battery can have excellent high-temperature cycle characteristics.

The counter cation in the monofluorophosphate and the difluorophosphate is not particularly limited, and lithium, sodium, potassium, magnesium, calcium, NR ¹²¹ R ¹²² R ¹²³ R ¹²⁴ (where R ^{121 to} R ¹²⁴ are independently And a hydrogen atom or an organic group having 1 to 12 carbon atoms). The organic group having 1 to 12 carbon atoms represented by R ^{121 to} R ¹²⁴ of the ammonium is not particularly limited, and may be, for example, an alkyl group optionally substituted by a fluorine atom, a halogen atom or an alkyl group. And an aryl group which may be substituted with a halogen atom or an alkyl group, a nitrogen atom-containing heterocyclic group which may have a substituent, and the like. Among them, R ^{121 to} R ¹²⁴ are independently preferably a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen-containing heterocyclic group, or the like. As the counter cation, lithium, sodium and potassium are preferable, and lithium is particularly preferable.

Examples of the monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate, and the like. Lithium monofluorophosphate and lithium difluorophosphate are preferred, and lithium difluorophosphate is more preferred.

As the monofluorophosphate and the difluorophosphate, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
The amount of one or more selected from monofluorophosphate and difluorophosphate (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more. , More preferably 0.1% by mass or more, further preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and can be 5% by mass or less, preferably 3% by mass. It is preferably at most 2% by mass, more preferably at most 1.5% by mass, particularly preferably at most 1% by mass. Within this range, the effect of improving the initial irreversible capacity is remarkably exhibited.

  The mass ratio of the compound represented by the above formula (1) and one or more kinds (in the case of two or more kinds, the total amount) selected from monofluorophosphates and difluorophosphates is represented by the formula (1). Compound: Monofluorophosphate and difluorophosphate are preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and particularly preferably 20:80 to 80:20. Within this range, the desired characteristics can be improved without lowering other battery characteristics.

1-3-2. Borate The borate is not particularly limited as long as it has at least one boron atom in the molecule. However, those corresponding to oxalates are described in 1-3-2. Instead of borate, 1-3-3. It shall be included in the oxalate. By using the compound represented by the formula (1) in combination with the borate in the electrolytic solution of the present invention, the initial characteristics and the storage characteristics are also improved, and a battery having excellent overcharge safety is obtained. .

Examples of the counter cation in the borate include lithium, sodium, potassium, magnesium, calcium, rubidium, cesium, barium and the like, and among them, lithium is preferable.
As the borate, a lithium salt is preferable, and a lithium borate-containing salt can also be suitably used. For example, LiBF ₄ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) _{2 and the} like. Among them, LiBF ₄ is more preferable because it has the effect of improving the initial charge / discharge efficiency and the high-temperature cycle characteristics.

One type of borate may be used alone, or two or more types may be used in any combination and in any ratio.
The amount of borate (the total amount in the case of two or more types) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably. Is at least 0.3% by mass, particularly preferably at least 0.4% by mass, and can be at most 10.0% by mass, preferably at most 5.0% by mass, more preferably at most 3.0% by mass. %, More preferably 2.0% by mass or less, particularly preferably 1.0% by mass or less. Within this range, side reactions of the battery negative electrode are suppressed, and it is difficult to increase the resistance.

As for the mass ratio of the compound represented by the formula (1) and the borate, the compound represented by the formula (1): borate is preferably 1:99 to 99: 1, and preferably 10:90 to 90: 10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and it is difficult to increase the resistance of the battery.
When a borate and LiPF ₆ are used as the electrolyte, the ratio of the molar content of the borate to the molar content of LiPF ₆ in the nonaqueous electrolyte is preferably 0.001 or more and 12 or less,
0.01 to 1.1 is more preferable, 0.01 to 1.0 is further preferable, and 0.01 to 0.7 is more preferable. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and the charge / discharge efficiency of the battery is improved.

1-3-3. Oxalate The oxalate is not particularly limited as long as it has at least one oxalic acid structure in the molecule. By using the compound represented by the formula (1) and the oxalate together in the electrolytic solution of the present invention, a battery having improved initial characteristics and storage characteristics can be obtained.
As the oxalate, a metal salt represented by the formula (9) is preferable. This salt is a salt having an oxalato complex as an anion.

(Where
M ¹ is an element selected from the group consisting of Group 1 and Group 2 and aluminum (Al) in the periodic table;
M ² is an element selected from the group consisting of transition metals, groups 13, 14 and 15 of the periodic table;
R ⁹¹ is a group selected from the group consisting of halogen, an alkyl group having 1 to 11 carbon atoms and a halogen-substituted alkyl group having 1 to 11 carbon atoms;
a and b are positive integers;
c is 0 or a positive integer;
d is an integer of 1 to 3. )
M ¹ is preferably lithium, sodium, potassium, magnesium, or calcium, and particularly preferably lithium, from the viewpoint of battery characteristics when the electrolytic solution of the present invention is used for a lithium secondary battery.

M ² is, in terms of electrochemical stability when used in the lithium secondary battery, boron and phosphorus are particularly preferable.
^Examples of R ⁹¹ include fluorine, chlorine, methyl, trifluoromethyl, ethyl, pentafluoroethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, and the like. Trifluoromethyl groups are preferred.

Examples of the metal salt represented by the formula (9) include the following.
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;
Of these, lithium bis (oxalato) borate and lithium difluorobis (oxalato) phosphate are preferred, and lithium bis (oxalato) borate is more preferred.

One kind of oxalate may be used alone, or two or more kinds thereof may be used in optional combination and ratio.
The amount of oxalate (in the case of two or more kinds, the total amount) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably. Is not less than 0.3% by mass, and can be not more than 10% by mass, preferably not more than 5% by mass, more preferably not more than 3% by mass, still more preferably not more than 2% by mass, particularly preferably not more than 1% by mass. % Or less. Within this range, it is easy to control output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, and the like.

The compound represented by the above formula (1) and the oxalate salt preferably have a mass ratio of the compound represented by the formula (1): oxalate of 1:99 to 99: 1, and preferably 10:90 to 90: 10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, side reactions on the positive and negative electrodes of the battery are well-balanced, and battery characteristics are easily improved.
1-3-4. Fluorosulfonate The fluorosulfonate is not particularly limited as long as it has at least one fluorosulfonic acid structure in the molecule. By using the compound represented by the above formula (1) in combination with the fluorosulfonic acid salt in the electrolytic solution of the present invention, a battery having improved initial characteristics and storage characteristics can be obtained.

The counter cation in the fluorosulfonate is not particularly limited, and lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ¹³¹ R ¹³² R ¹³³ R ¹³⁴ (wherein, R ^{131 to} R ¹³⁴ are Each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms). For illustrative and preferred examples of R ¹³¹ to R ¹³⁴ may, ^R 131 ^{to R 134} in the 1-2-2 is applied. As the counter cation, lithium, sodium and potassium are preferable, and lithium is particularly preferable.

  Examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate and cesium fluorosulfonate, with lithium fluorosulfonate being preferred. An imide salt having a fluorosulfonic acid structure such as lithium bis (fluorosulfonyl) imide can also be used as the fluorosulfonic acid salt.

As the fluorosulfonate, one type may be used alone, or two or more types may be used in any combination and in any ratio.
The content of fluorosulfonate (in the case of two or more kinds, the total amount) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, It is still more preferably 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, furthermore It is preferably at most 2% by mass, particularly preferably at most 1% by mass. Within this range, there are few side reactions in the battery, and it is difficult to increase the resistance.

The compound represented by the formula (1) and the fluorosulfonic acid salt preferably have a mass ratio of the compound represented by the formula (1): fluorosulfonic acid salt of 1:99 to 99: 1, preferably 10:90 to 100: 99. 90:10 is more preferred, and 20:80 to 80:20 is particularly preferred. Within this range, a side reaction in the battery is appropriately suppressed, and the high-temperature durability is hardly reduced.
1-4. Non-aqueous solvent The non-aqueous solvent in the present invention is not particularly limited, and a known organic solvent can be used. Specific examples include cyclic carbonates, chain carbonates, cyclic and chain carboxylic esters, ether compounds, and sulfone compounds that do not have a fluorine atom.

In addition, in this specification, the volume of the nonaqueous solvent is a value measured at 25 ° C., but for a solid such as ethylene carbonate at 25 ° C., the value measured at the melting point is used.
1-4-1. Cyclic carbonate having no fluorine atom Examples of the cyclic carbonate having no fluorine atom include a cyclic carbonate having an alkylene group having 2 to 4 carbon atoms.

Specific examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms and having no fluorine atom include ethylene carbonate, propylene carbonate, and butylene carbonate. Among them, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics derived from the improvement of the degree of dissociation of lithium ions.
As the cyclic carbonate having no fluorine atom, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.

  The compounding amount of the cyclic carbonate having no fluorine atom is not particularly limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. However, when one kind is used alone, the compounding amount is 100 vol. %, 5% by volume or more, more preferably 10% by volume or more. By setting the content in this range, it is possible to avoid a decrease in electric conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and to improve the large current discharge characteristics, stability to the negative electrode, and cycle characteristics of the non-aqueous electrolyte secondary battery. Range. Further, it is 95% by volume or less, more preferably 90% by volume or less, further preferably 85% by volume or less. By setting the content in this range, the viscosity of the non-aqueous electrolyte is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the load characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range.

1-4-2. Chain carbonate As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
Examples of the linear carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl carbonate, and tert. -Butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, tert-butyl ethyl carbonate and the like.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, chain carbonates having a fluorine atom (hereinafter sometimes referred to as “fluorinated chain carbonate”) can also be suitably used.

The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or to different carbons.
Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate and its derivatives, fluorinated ethyl methyl carbonate and its derivatives, fluorinated diethyl carbonate and its derivatives, and the like.

Examples of the fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate and the like. Can be
Examples of fluorinated ethyl methyl carbonate and derivatives thereof include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate and the like.

  Examples of the fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, and ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate and the like can be mentioned.

  One type of chain carbonate may be used alone, or two or more types may be used in combination in any combination and in any ratio. The mixing amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the nonaqueous solvent. By setting the lower limit in this manner, the viscosity of the non-aqueous electrolyte is set to an appropriate range, the decrease in ionic conductivity is suppressed, and thus the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range. Become. Further, the chain carbonate content is preferably 90% by volume or less, more preferably 85% by volume or less, in 100% by volume of the nonaqueous solvent. By setting the upper limit in this manner, it is possible to avoid a decrease in electric conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and to easily set the large current discharge characteristics of the non-aqueous electrolyte secondary battery to a favorable range. .

1-4-3. Cyclic carboxylic acid ester As the cyclic carboxylic acid ester, those having 3 to 12 carbon atoms are preferable.
Specific examples include gamma butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like. Among them, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics derived from the improvement of the degree of dissociation of lithium ions.

As the cyclic carboxylic acid ester, one type may be used alone, or two or more types may be used in optional combination and ratio.
The compounding amount of the cyclic carboxylic acid ester is usually preferably 5% by volume or more, more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. Within this range, the electric conductivity of the non-aqueous electrolyte can be improved, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery can be easily improved. The amount of the cyclic carboxylic acid ester is preferably 50% by volume or less, more preferably 40% by volume or less. By setting the upper limit in this manner, the viscosity of the non-aqueous electrolyte is set to an appropriate range, a decrease in electric conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. The characteristics can be easily set in a good range.

1-4-4. Ether Compound As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms in which a part of hydrogen may be substituted by fluorine are preferable.
As a chain ether having 3 to 10 carbon atoms,
Diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2 2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2-trifluoroethyl) ether, (2-fluoroethyl ) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propylether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetra) Fluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl) (3-fluoro- n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propylether, (2,2,2- (Trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2 , 2-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro- n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1, 1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro -N-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propylether, (n- Propyl) (3-fluoro (N-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, (3-fluoro-n-propyl) (3 , 3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) ) (2,2,3,3- Trafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3 , 3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di ( 2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butylether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-tri Fluoroethoxy) methane Methoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2 2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) Methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1,1 , 2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2,2) -Trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy Si (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2 -Fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) Ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n- Propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,4-dioxane, and the like, and fluorinated compounds thereof.
Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether have a high solvating ability to lithium ions and improve ion dissociation. From the viewpoint of low viscosity and high ionic conductivity, dimethoxymethane, diethoxymethane and ethoxymethoxymethane are preferred.

One of the ether compounds may be used alone, or two or more thereof may be used in any combination and in any ratio.
The compounding amount of the ether compound is usually 5% by volume or more, more preferably 10% by volume or more, still more preferably 15% by volume or more, and preferably 70% by volume or less in 100% by volume of the non-aqueous solvent. It is more preferably at most 60% by volume, still more preferably at most 50% by volume. Within this range, it is easy to secure the effect of improving the degree of dissociation of lithium ions of the chain ether and the improvement of the ion conductivity derived from the decrease in viscosity. It is easy to avoid a situation where the capacity is reduced due to the co-insertion.

1-4-5. Sulfone-based compound As the sulfone-based compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably one or two.
Examples of the cyclic sulfone having 3 to 6 carbon atoms include monosulfone compounds such as trimethylene sulfone, tetramethylene sulfone, and hexamethylene sulfone;
Examples of the disulfone compound include trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones.

Among them, from the viewpoints of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.
As the sulfolane, sulfolane and / or a sulfolane derivative (hereinafter sometimes referred to as “sulfolane” including sulfolane) is preferable. As the sulfolane derivative, one in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.

Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methylsulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ion conductivity and high input / output characteristics.

Further, as a chain sulfone having 2 to 6 carbon atoms,
Dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl Sulfone, tert-butyl methyl sulfone, tert-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoro Ethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone , Perfluoroethylmethylsulfone, ethyltrifluoroethylsulfone, ethylpentafluoroethylsulfone, di (trifluoroethyl) sulfone, perfluorodiethylsulfone, fluoromethyl-n-propylsulfone, difluoromethyl-n-propylsulfone, Fluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoro Ethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-tert-butyl sulfone, pen Trifluoroethyl -n- butyl sulfone, pentafluoroethyl -tert- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone Trifluoroethyl-n-butylsulfone, trifluoroethyl-tert-butylsulfone, trifluoromethyl-n-butylsulfone, trifluoromethyl-tert-butylsulfone, etc. have high ion conductivity and high input / output characteristics. preferable.

One of the sulfone compounds may be used alone, or two or more thereof may be used in any combination and in any ratio.
The blending amount of the sulfone compound is usually preferably at least 0.3% by volume, more preferably at least 1% by volume, still more preferably at least 5% by volume, and preferably at least 40% by volume, in 100% by volume of the nonaqueous solvent. It is at most 35% by volume, more preferably at most 35% by volume, still more preferably at most 30% by volume. Within this range, the effect of improving the durability such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be adjusted to an appropriate range to prevent a decrease in electric conductivity. When charging / discharging the aqueous electrolyte secondary battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

1-4-6. Composition of Non-Aqueous Solvent As the non-aqueous solvent of the present invention, one of the above-described non-aqueous solvents may be used alone, or two or more may be used in any combination and in any ratio.
For example, one of the preferable combinations of the non-aqueous solvent includes a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate.

  Among them, the total of the cyclic carbonate having no fluorine atom and the chain carbonate occupying the nonaqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, further preferably 90% by volume or more, And the proportion of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, It is preferably at most 50% by volume, more preferably at most 35% by volume, still more preferably at most 30% by volume, particularly preferably at most 25% by volume.

When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and the high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of the battery manufactured using the combination may be improved.
For example, as a preferred combination of a cyclic carbonate and a chain carbonate having no fluorine atom,
Ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate and diethyl carbonate and ethyl methyl carbonate, ethylene carbonate And dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

  Among the combination of a cyclic carbonate having no fluorine atom and a chain carbonate, those containing an asymmetric chain alkyl carbonate as the chain carbonate are more preferable, particularly, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, Those containing ethylene carbonate such as ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, and ethylene carbonate such as ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, symmetric chain carbonates and asymmetric chain carbonates have cycle characteristics and large current discharge characteristics. Is preferable because of good balance.

Above all, the asymmetric chain carbonates are preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
A combination obtained by further adding propylene carbonate to these combinations of ethylene carbonate and chain carbonates is also a preferred combination.
When propylene carbonate is contained, the volume ratio between ethylene carbonate and propylene carbonate is preferably from 99: 1 to 40:60, and particularly preferably from 95: 5 to 50:50. Further, the proportion of propylene carbonate in the whole non-aqueous solvent is preferably 0.1% by volume or more, more preferably 1% by volume or more, still more preferably 2% by volume or more, and preferably 20% by volume or less, more preferably Is at most 8% by volume, more preferably at most 5% by volume.

It is preferable to include propylene carbonate in this concentration range, because the low-temperature characteristics may be further improved while maintaining the characteristics of the combination of ethylene carbonate and chain carbonate.
When dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably at least 10% by volume, more preferably at least 20% by volume, further preferably at least 25% by volume, particularly preferably at least 25% by volume. It is preferably at least 30% by volume, more preferably at most 90% by volume, more preferably at most 80% by volume, still more preferably at most 75% by volume, particularly preferably at most 70% by volume, The load characteristics of the battery may be improved.

Above all, by containing dimethyl carbonate and ethyl methyl carbonate, and by increasing the content of dimethyl carbonate to be greater than the content of ethyl methyl carbonate, the battery characteristics after high-temperature storage are improved while maintaining the electrical conductivity of the electrolytic solution. Is preferred.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate (dimethyl carbonate / ethyl methyl carbonate) in the total nonaqueous solvent is 1.1 or more in terms of improving the electric conductivity of the electrolytic solution and improving the battery characteristics after storage. Is preferably 1.5 or more, and more preferably 2.5 or more. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.

In the combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate, a cyclic carboxylate, a chain carboxylate, a cyclic ether, a chain ether, a sulfur-containing organic solvent, Other solvents such as a phosphorus organic solvent and an aromatic fluorinated solvent may be mixed.
1-5. Auxiliary In the electrolyte battery of the present invention, an auxiliary may be appropriately used depending on the purpose, in addition to the above compounds. Examples of the assistant include other assistants shown below.

1-5-1. Other auxiliaries Other known auxiliaries can be used for the electrolytic solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate and methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, and anhydride. Carboxylic anhydrides such as itaconic acid, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 3,9-divinyl-2,4,8,10-tetracarboxylic acid Spiro compounds such as oxaspiro [5.5] undecane; sulfur-containing compounds such as N, N-dimethylmethanesulfonamide and N, N-diethylmethanesulfonamide; trimethyl phosphite, triethyl phosphite, triphosphite Phenyl, trimethyl phosphate, triethyl phosphate, Phosphorus-containing compounds such as triphenyl acid, methyl dimethyl phosphinate, ethyl diethyl phosphinate, trimethyl phosphine oxide, triethyl phosphine oxide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone And nitrogen-containing compounds such as 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane; 2-propynyl 2- (diethoxyphosphoryl) acetate , 1-methyl-2-propynyl 2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propynyl 2- (diethoxyphosphoryl) acetate, pentafluorophenylmethanesulfonate, pentafluorophenyltrifluoromethane Pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, methyl pentafluorophenyl carbonate, 2-propynyl 2- (methanesulfonyloxy) propionate, 2-methyl 2- (methanesulfonyloxy) propionate, 2- ( 2-ethyl methanesulfonyloxy) propionate, 2-propynyl methanesulfonyloxyacetate, 2-methyl methanesulfonyloxyacetate, 2-ethyl methanesulfonyloxyacetate, lithium ethyl methyloxycarbonyl phosphonate, lithium ethyl ethyloxycarbonyl phosphonate, lithium ethyl 2-propynyloxycarbonyl phosphonate, lithium ethyl 1-methyl-2-propynyloxycarbonyl phosphonate, lithium ethyl 1,1 Dimethyl-2-propynyloxy carbonyl phosphonate, lithium methyl sulfate, lithium ethyl sulfate, lithium 2-propynyl sulfate, lithium 1-methyl-2-propynyl sulfate, lithium 1,1-dimethyl-2
-Propynyl sulfate, lithium 2,2,2-trifluoroethyl sulfate, methyl trimethylsilyl sulfate, ethyl trimethylsilyl sulfate, 2-propynyl trimethylsilyl sulfate, dilithium ethylene disulfate, 2-butyne-1,4-diyldimethanesulfonate, 2-butyne -1,4-diyldiethanesulfonate, 2-butyne-1,4-diylformate, 2-butyne-1,4-diyldiacetate, 2-butyne-1,4-diyldipropionate, 4-hexadiyne-1, 6-diyl dimethanesulfonate, 2-propynyl methanesulfonate, 1-methyl-2-propynyl methanesulfonate, 1,1-dimethyl-2-propynyl methanesulfonate, 2-propynyl eta Sulfonate, 2-propynyl vinylsulfonate, methyl 2-propynyl carbonate, ethyl 2-propynyl carbonate, bis (2-propynyl) carbonate, methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, bis (2-propynyl) oxalate, 2- Propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, di (2-propynyl) glutarate, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolane- 4-yl propionate, 5-methyl-1,2-oxathiolan-4-one 2,2-dioxide, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxide, 2-isocyana Ethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2-isocyanatoethoxy) ethyl acrylate, 2- (2-isocyanatoethoxy) ethyl methacrylate, 2- (2-isocyanatoethoxy) Ethyl crotonate, 2-allyl succinic anhydride, 2- (1-penten-3-yl) succinic anhydride, 2- (1-hexen-3-yl) succinic anhydride, 2- (1-hepten-3-yl) ) Succinic anhydride, 2- (1-octen-3-yl) succinic anhydride, 2- (1-nonen-3-yl) succinic anhydride, 2- (3-buten-2-yl) succinic anhydride, Examples thereof include 2- (2-methylallyl) succinic anhydride and 2- (3-methyl-3-buten-2-yl) succinic anhydride. These may be used alone or in combination of two or more. By adding these auxiliaries, the capacity retention characteristics after high-temperature storage and the cycle characteristics can be improved.

  The amount of the other auxiliaries is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. Other auxiliary agents are preferably 0.01% by mass or more, and 5% by mass or less, in 100% by mass of the non-aqueous electrolyte. Within this range, the effects of the other auxiliary agents can be sufficiently exhibited, and a situation in which the battery characteristics such as high-load discharge characteristics are deteriorated can be easily avoided. The compounding amount of other auxiliaries is more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, and more preferably 3% by mass or less, and further preferably 1% by mass or less. .

2. Battery Configuration The electrolyte battery of the present invention is suitable for use as an electrolyte for a secondary battery, for example, a lithium secondary battery among non-aqueous electrolyte secondary batteries. Hereinafter, a non-aqueous electrolyte secondary battery using the electrolyte of the present invention will be described.
The electrolyte battery of the present invention can have a known structure, and typically includes a negative electrode and a positive electrode capable of inserting and extracting metal ions (for example, lithium ions), and the above-mentioned electrolytic solution of the present invention. Prepare.

2-1. Negative electrode The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release metal ions (eg, lithium ions). Specific examples include a carbonaceous material, an alloy-based material, and a lithium-containing metal composite oxide material. These may be used alone or in any combination of two or more.

<Negative electrode active material>
Examples of the negative electrode active material include a carbonaceous material, an alloy-based material, and a lithium-containing metal composite oxide material.
As the carbonaceous material used as the negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous substance and an artificial graphite substance at least once in the range of 400 to 3200 ° C;
(3) a carbonaceous material in which the negative electrode active material layer is made of at least two or more kinds of carbonaceous materials having different crystallinities, and / or having an interface where the differently crystalline carbonaceous materials are in contact with each other;
(4) a carbonaceous material in which the negative electrode active material layer is made of at least two or more kinds of carbonaceous materials having different orientations and / or having an interface where the carbonaceous materials having different orientations are in contact with each other;
Of these, a good balance between the initial irreversible capacity and the high current density charge / discharge characteristics is preferable. In addition, as the carbonaceous materials (1) to (4), one type may be used alone, or two or more types may be used in any combination and in any ratio.

  The artificial carbonaceous material and artificial graphite material of the above (2) include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch and those obtained by oxidizing these pitches, needle coke, pitch coke and Thermal decomposition products of organic substances such as carbon materials, furnace black, acetylene black, pitch-based carbon fiber, carbonized organic substances, and carbonizable organic substances such as benzene, toluene, xylene, and quinoline. , A solution dissolved in a low molecular organic solvent such as n-hexane, and a carbide thereof.

  As the alloy-based material used as the negative electrode active material, as long as it can occlude and release lithium, simple lithium, a simple metal and an alloy forming a lithium alloy, or an oxide, carbide, nitride, silicide, sulfide, or the like thereof Or a compound such as a phosphide, and is not particularly limited. The elemental metal or alloy forming the lithium alloy is preferably a material containing a metal or metalloid element of group 13 and 14 (that is, excluding carbon), and more preferably aluminum, silicon and tin (hereinafter, referred to as “ Element metal) and alloys or compounds containing these atoms. One of these may be used alone, or two or more may be used in any combination and in any ratio.

  As the negative electrode active material having at least one type of atom selected from the specific metal elements, a metal simple substance of any one specific metal element, an alloy composed of two or more specific metal elements, one or two or more specific metal elements Alloys composed of metal elements and other one or more metal elements, compounds containing one or more specific metal elements, and oxides, carbides, nitrides, silicides of the compounds , Sulfide or phosphide. By using these metals alone, alloys or metal compounds as the negative electrode active material, it is possible to increase the capacity of the battery.

  Further, a compound in which these composite compounds are intricately bonded to several kinds of elements such as a simple metal, an alloy, or a nonmetallic element is also included. Specifically, for example, in the case of silicon or tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. For example, in the case of tin, it is also possible to use a complex compound containing 5 to 6 types of elements in combination with a metal acting as a negative electrode other than tin and silicon, a metal not operating as a negative electrode, and a nonmetallic element. it can.

Among these negative electrode active materials, since the capacity per unit mass is large when formed into a battery, a single metal of any one specific metal element, an alloy of two or more specific metal elements, or oxidation of the specific metal element , Carbides, nitrides, and the like are preferable, and particularly, simple metals and alloys of silicon and / or tin, oxides, carbides, nitrides, and the like are preferable from the viewpoint of the capacity per unit mass and the environmental load.

  The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but is preferably a material containing titanium and lithium from the viewpoint of high current density charge / discharge characteristics, More preferably, a lithium-containing composite metal oxide material containing titanium is preferable, and further a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as “lithium-titanium composite oxide”). That is, it is particularly preferable to use a lithium-titanium composite oxide having a spinel structure contained in a negative electrode active material for a non-aqueous electrolyte secondary battery because output resistance is greatly reduced.

Further, lithium or titanium of the lithium-titanium composite oxide is at least selected from the group consisting of other metal elements, for example, Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. Those substituted with one kind of element are also preferable.
The metal oxide is a lithium-titanium composite oxide represented by the formula (A), and in the formula (A), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, 0 ≦ It is preferable that z ≦ 1.6 because the structure at the time of doping and undoping of lithium ions is stable.

_{Li x Ti y M z O 4} (A)
[In the formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. ]
Among the compositions represented by the above formula (A),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
Is particularly preferred because of the good balance of battery performance.

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is mentioned as a preferable example.

<Physical properties of carbonaceous materials>
When a carbonaceous material is used as the negative electrode active material, the material preferably has the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) of the carbonaceous material obtained by X-ray diffraction according to the Gakushin method is preferably 0.335 nm or more, and usually 0.360 nm or less. It is preferably 350 nm or less, more preferably 0.345 nm or less. Further, the crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction according to the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The mass-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) determined by a laser diffraction / scattering method and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and more preferably 7 μm. The above is particularly preferred, and usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to an initial battery capacity loss. On the other hand, if it exceeds the above range, an uneven coating surface is likely to be formed when producing an electrode by coating, which may be undesirable in a battery manufacturing process.
The volume-based average particle size is measured by dispersing a carbon powder in a 0.2% by mass aqueous solution (about 10 mL) of a surfactant, polyoxyethylene (20) sorbitan monolaurate, and then performing a laser diffraction / scattering type particle size distribution. The measurement is performed using a total meter (LA-700 manufactured by Horiba, Ltd.).

(Raman R value, Raman half width)
The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1.5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

Further, the Raman half width around 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and is usually 100 cm ⁻¹ or less, and is preferably 80 cm ⁻¹ or less. Preferably, it is 60 cm ^-1 or less, more preferably 40 cm ^-1 or less.
The Raman R value and the Raman half width are indices indicating the crystallinity of the surface of the carbonaceous material. The carbonaceous material has appropriate crystallinity from the viewpoint of chemical stability, and Li enters by charge and discharge. It is preferable that the crystallinity be such that sites between layers do not disappear, that is, charge acceptability does not decrease. When the density of the negative electrode is increased by pressing after being applied to the current collector, the crystal is likely to be oriented in a direction parallel to the electrode plate. When the Raman R value or the Raman half-value width is within the above range, a suitable film can be formed on the negative electrode surface to improve storage characteristics, cycle characteristics, and load characteristics, and the efficiency accompanying the reaction with the non-aqueous electrolyte solution. Reduction and gas generation can be suppressed.

The measurement of the Raman spectrum is performed by using a Raman spectrometer (Raman spectrometer manufactured by JASCO Corporation) to allow the sample to naturally fall into the measurement cell, fill the sample, and irradiate the sample surface in the cell with argon ion laser light. This is performed by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity IA of a peak PA around 1580 cm ^-1, and measuring the intensity IB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IB / IA) .

The above Raman measurement conditions are as follows.
・ Argon ion laser wavelength: 514.5 nm
・ Laser power on sample: 15-25mW
-Resolution: 10 to 20 cm ^-1
- Measuring ^range: 1100cm ^-1 ~1730cm -1
・ Raman R value, Raman half width analysis: background processing ・ Smoothing processing: simple average, convolution 5 points

(BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · ^{g -1} or more, 0.7 m ² · ^{g -1} or more, 1. 0 m ² · ^{g -1} or more, and particularly preferably 1.5 m ² · ^{g -1} or more, generally not more than 100 m ² · ^{g -1,} preferably ^{25 m} 2 · ^{g -1} or less, 15 m ² · g ⁻¹ or less is more preferable, and 10 m ² · g ⁻¹ or less is particularly preferable.

When the value of the BET specific surface area is within the above range, precipitation of lithium on the electrode surface can be suppressed, while gas generation due to reaction with the non-aqueous electrolyte can be suppressed.
The measurement of the specific surface area by the BET method is performed by preliminarily drying the sample at 350 ° C. for 15 minutes under a nitrogen flow using a surface area meter (a full automatic surface area measuring device manufactured by Okura Riken), and then measuring the nitrogen content relative to the atmospheric pressure. Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure becomes 0.3, a nitrogen adsorption BET one-point method by a gas flow method is used.

(Roundness)
When the circularity is measured as the degree of sphere of the carbonaceous material, it is preferable that the degree falls within the following range. The circularity is defined by “circularity = (perimeter of equivalent circle having the same area as the particle projection shape) / (actual perimeter of particle projection shape)”. It becomes a true sphere. The circularity of the carbonaceous material having a particle diameter in the range of 3 to 40 μm is preferably as close to 1 as possible, more preferably 0.1 or more, particularly preferably 0.5 or more, more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. As for the high current density charge / discharge characteristics, as the degree of circularity increases, the filling property improves, and the resistance between particles can be suppressed, so that the high current density charge / discharge characteristics improve. Therefore, it is preferable that the degree of circularity be as high as the above range.

  The circularity is measured using a flow-type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample is dispersed in a 0.2% by mass aqueous solution (about 50 mL) of a polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with ultrasonic waves of 28 kHz for 1 minute at an output of 60 W. The detection range is specified to be 0.6 to 400 μm, and measurement is performed for particles having a particle size in the range of 3 to 40 μm.

  The method for improving the degree of circularity is not particularly limited, but it is preferable that the spherical shape is obtained by performing a spheroidizing treatment because the shape of the interparticle space when the electrode is formed is formed. Examples of the spheroidizing treatment include a method of mechanically approaching a spherical shape by applying a shear force and a compressive force, and a mechanical and physical treatment method of granulating a plurality of fine particles by a binder or an adhesive force of the particles themselves. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and more preferably 1 g · cm ⁻³ or more. particularly preferred, and is preferably 2 g · ^{cm -3} or less, more preferably 1.8 g · ^{cm -3} or less, 1.6 g · ^{cm -3} or less are particularly preferred. When the tap density is within the above range, the battery capacity can be ensured, and the increase in resistance between particles can be suppressed.

The tap density is measured by passing the sample through a sieve having an opening of 300 μm, dropping the sample into a tapping cell of 20 cm ³ and filling the sample up to the upper end surface of the cell, and then using a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Tapping with a stroke length of 10 mm is performed 1000 times using a tap densifier), and the tap density is calculated from the mass at that time and the mass of the sample.

(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is within the above range, excellent high-density charge / discharge characteristics can be secured. Note that the upper limit of the above range is the theoretical upper limit of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after forming a sample under pressure. A molded body obtained by filling 0.47 g of a sample into a molding machine having a diameter of 17 mm and compressing the molded body at 58.8 MN · m ⁻² was set using clay to be flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the peak intensities of (110) diffraction and (004) diffraction of the obtained carbon, (110) diffraction peak intensity / (
004) Calculate the ratio represented by the diffraction peak intensity.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree, measurement range and step angle / measurement time:
(110) plane: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) plane: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds

(Aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 5 or less. When the content is in the above range, streaking at the time of forming the electrode plate is suppressed, and more uniform coating is possible, so that excellent high current density charge / discharge characteristics can be secured. Note that the lower limit of the above range is the theoretical lower limit of the aspect ratio of the carbonaceous material.

  The measurement of the aspect ratio is performed by observing the particles of the carbonaceous material under magnification with a scanning electron microscope. 50 arbitrary graphite particles fixed on the end face of a metal having a thickness of 50 μm or less are selected, and the stage on which the sample is fixed is rotated and tilted for each of the particles, and the carbonaceous material particles are observed three-dimensionally. Is measured, and the shortest diameter B perpendicular to the longest diameter A is measured, and the average value of A / B is obtained.

<Structure of negative electrode and fabrication method>
Any known method can be used for manufacturing the electrode as long as the effects of the present invention are not significantly impaired. For example, to form a slurry by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, and the like to the negative electrode active material, applying the slurry to a current collector, drying, and then pressing the slurry. Can be.

When an alloy-based material is used, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a method such as a vapor deposition method, a sputtering method, and a plating method is also used.
(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector of the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel, and copper is particularly preferable in terms of processability and cost.

When the current collector is a metal material, examples of the shape of the current collector include a metal foil, a metal column, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foamed metal. Among them, a metal thin film, more preferably a copper foil, more preferably a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method, both of which can be used as a current collector.
The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less from the viewpoints of securing the battery capacity and handling.

(Ratio of thickness between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the thickness of the negative electrode active material layer is not particularly limited, but the value of “(thickness of the negative electrode active material layer on one side immediately before injection of the non-aqueous electrolyte) / (thickness of the current collector)” However, it is preferably 150 or less, more preferably 20 or less, particularly preferably 10 or less, and preferably 0.1 or more, more preferably 0.4 or more, and particularly preferably 1 or more. When the thickness ratio between the current collector and the negative electrode active material layer is within the above range, the battery capacity can be ensured, and heat generation of the current collector during high current density charging and discharging can be suppressed.

(Binder)
The binder that binds the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the nonaqueous electrolytic solution and the solvent used in manufacturing the electrode.
Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, Rubber-like polymers such as NBR (acrylonitrile-butadiene rubber) and ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or hydrogenated product thereof; EPDM (ethylene-propylene-diene terpolymer), styrene Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Ethylene-vinyl acetate copolymer, propylene / α-olefin copolymer and other soft resinous polymers; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). One of these may be used alone, or two or more thereof may be used in any combination and in any ratio.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, and more preferably 15% by mass. The content is more preferably 10% by mass or less, particularly preferably 8% by mass or less. When the ratio of the binder to the negative electrode active material is in the above range, the battery capacity and the strength of the negative electrode can be sufficiently ensured.

  In particular, when a rubber-like polymer represented by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, It is more preferably at least 0.6% by mass, and usually at most 5% by mass, preferably at most 3% by mass, more preferably at most 2% by mass. Further, when a fluorine-based polymer typified by polyvinylidene fluoride is contained as a main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more. Preferably, it is usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and the conductive material used as necessary. Instead, either an aqueous solvent or an organic solvent may be used.
Examples of the aqueous solvent include water, alcohol, and the like. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N- Examples include dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, hexamethylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.
In particular, when an aqueous solvent is used, it is preferable that a dispersant or the like is contained in addition to the thickener, and the slurry is formed using a latex such as SBR. One of these solvents may be used alone, or two or more thereof may be used in any combination and in any ratio.

(Thickener)
Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, but specific examples include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio.

  When a thickener is further used, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Further, it is usually at most 5% by mass, preferably at most 3% by mass, more preferably at most 2% by mass. When the ratio of the thickener to the negative electrode active material is in the above range, a decrease in battery capacity and an increase in resistance can be suppressed, and good applicability can be ensured.

(Electrode density)
Although the electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and more preferably 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · ^{cm -3} or more, preferably 2.2 g · ^{cm -3} or less, more preferably 2.1 g · ^{cm -3} or less, 2.0 g · ^{cm -3} or less More preferred is 1.9 g · cm ⁻³ or less. When the density of the negative electrode active material existing on the current collector is within the above range, the destruction of the negative electrode active material particles is prevented, the initial irreversible capacity is increased, and the density of the current collector / negative electrode active material interface is reduced. In addition, it is possible to suppress the deterioration of the high current density charge / discharge characteristics due to the decrease in the permeability of the nonaqueous electrolyte solution, while suppressing the decrease in battery capacity and the increase in resistance.

(Thickness of negative electrode plate)
The thickness of the negative electrode plate is designed according to the positive electrode plate to be used, and is not particularly limited, but the thickness of the mixture layer obtained by subtracting the thickness of the metal foil of the core is usually 15 μm or more, preferably 20 μm or more. , More preferably 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, and more preferably 250 μm or less.

(Surface coating of negative electrode plate)
Further, a material in which a substance having a different composition from the substance attached to the surface of the negative electrode plate may be used. Examples of surface adhering substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate. And carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

2-2. Positive electrode <Positive electrode active material>
Hereinafter, the positive electrode active material used for the positive electrode will be described.
(composition)
The positive electrode active material is not particularly limited as long as it can occlude and release metal ions (for example, lithium ions) electrochemically. For example, a material containing lithium and at least one transition metal is preferable. Specific examples include a lithium transition metal composite oxide and a lithium-containing transition metal phosphate compound.

As the transition metal of the lithium transition metal composite oxide, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples thereof include lithium-cobalt composite oxides such as LiCoO ₂ and LiNiO ₂ . Lithium / nickel composite oxide, lithium / manganese composite oxide such as LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO ₄ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O Lithium-nickel-manganese-cobalt composite oxides such as No. ₂ and some of the transition metal atoms which are the main components of these lithium transition metal composite oxides are Na, K, B, F, Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W and the like. As the substituted ones, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _{0 .45} Co _0.10 Al _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples are LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Iron phosphates such as LiFeP ₂ O _7, cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms which are the main components of these lithium transition metal phosphate compounds are replaced with Al, Ti, V, Cr, Mn, Fe , Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc.

  In addition, it is preferable to include lithium phosphate in the positive electrode active material because continuous charging characteristics are improved. Although the use of lithium phosphate is not limited, it is preferable to use a mixture of the above positive electrode active material and lithium phosphate. The lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass, based on the total of the positive electrode active material and lithium phosphate. %, And the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

(Surface coating)
Alternatively, a material in which a material having a different composition is attached to the surface of the positive electrode active material may be used. Examples of surface adhering substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate. And carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.

  These surface adhering substances are, for example, dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, and then dried.The surface adhering substance precursor is dissolved or suspended in a solvent and then impregnated and added to the positive electrode active material. The reaction can be carried out by heating or the like, or can be added to the surface of the positive electrode active material by, for example, a method of adding the precursor to the positive electrode active material precursor and firing the same at the same time. In the case of attaching carbon, a method of mechanically attaching carbonaceous material later, for example, in the form of activated carbon or the like can also be used.

The amount of the surface adhering substance is preferably 0.1 ppm or more as a lower limit, more preferably 1 ppm or more, still more preferably 10 ppm or more, and as an upper limit, preferably 20% or less, more preferably by mass with respect to the positive electrode active material. Is used at 10% or less, more preferably at 5% or less. Oxidation reaction of the electrolytic solution on the surface of the positive electrode active material can be suppressed by the surface adhering substance, and the battery life can be improved. However, if the adhering amount is too small, the effect is not sufficiently exhibited, and If it is too much, the resistance may increase due to hindrance of lithium ions.
In the present invention, a substance having a different composition from the surface of the positive electrode active material is also referred to as a “positive electrode active material”.

(shape)
The shape of the particles of the positive electrode active material may be a lump, a polyhedron, a sphere, an oval sphere, a plate, a needle, a column, or the like, as conventionally used. Further, the primary particles may be aggregated to form secondary particles.

(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and still more preferably 1.0 g / cm ³ or more. When the tap density of the positive electrode active material is in the above range, the necessary amount of the dispersion medium and the required amount of the conductive material and the binder at the time of forming the positive electrode active material layer can be suppressed, and as a result, the filling rate of the positive electrode active material and the battery Capacity can be secured. By using a composite oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. Generally, the higher the tap density, the better, and there is no particular upper limit, but it is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and still more preferably 3.5 g / cm ³ or less. Within the above range, a decrease in load characteristics can be suppressed.
In the present invention, the tap density is defined as a powder filling density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.

(Median diameter d50)
The median diameter d50 of the particles of the positive electrode active material (the secondary particle diameter when the primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and still more preferably. Is at least 0.8 μm, most preferably at least 1.0 μm, and the upper limit is preferably at most 30 μm, more preferably at most 27 μm, further preferably at most 25 μm, most preferably at most 22 μm. When the content is in the above range, a high tap density product is obtained, and a decrease in battery performance can be suppressed.On the other hand, when preparing a positive electrode of a battery, that is, when applying a slurry of an active material and a conductive material or a binder with a solvent to apply a thin film, And problems such as streaking can be prevented. Here, by mixing two or more kinds of the positive electrode active materials having different median diameters d50, the filling property at the time of manufacturing the positive electrode can be further improved.

  In the present invention, the median diameter d50 is measured by a known laser diffraction / scattering type particle size distribution analyzer. When using LA-920 manufactured by HORIBA as a particle size distribution meter, a 0.1% by mass aqueous sodium hexametaphosphate solution is used as a dispersion medium used for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.

(Average primary particle diameter)
When the primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.1 μm or more. It is at least 2 μm, and the upper limit is preferably at most 5 μm, more preferably at most 4 μm, further preferably at most 3 μm, most preferably at most 2 μm. When the content is in the above range, the powder filling property and the specific surface area can be ensured, and the decrease in battery performance can be suppressed. On the other hand, the reversibility of charge and discharge can be ensured by obtaining appropriate crystallinity. .

  In the present invention, the primary particle size is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest value of the intercept of the left and right borders of the primary particle with respect to the horizontal straight line is determined for any 50 primary particles, and the average value is determined. Can be

(BET specific surface area)
The BET specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, further preferably 0.3 m ² / g or more, and the upper limit is 50 m ² / g or less. , Preferably 40 m ² / g or less, more preferably 30 m ² / g or less. When the BET specific surface area is within the above range, battery performance can be ensured, and good coatability of the positive electrode active substance can be maintained.

  In the present invention, the BET specific surface area was measured by using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), pre-drying the sample at 150 ° C. for 30 minutes under a nitrogen flow, and then measuring the atmospheric pressure. Is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas accurately prepared so that the value of nitrogen relative pressure becomes 0.3.

(Production method of positive electrode active material)
As a method for producing the positive electrode active material, a general method for producing an inorganic compound is used. In particular, various methods can be considered for producing a spherical or elliptical active material.For example, a transition metal raw material is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring. A spherical precursor is produced and collected, and dried if necessary. Then, a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ is added and calcined at a high temperature to obtain an active material. .

For the production of a positive electrode, the above-mentioned positive electrode active material may be used alone, or one or more kinds of different compositions may be used in any combination or ratio. As a preferable combination in this case, a combination of LiCoO ₂ and LiMn ₂ O ₄ such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ or a material obtained by partially replacing Mn with another transition metal or the like is preferable. Or a combination of LiCoO ₂ or a material obtained by substituting a part of Co with another transition metal or the like.

<Structure of cathode and fabrication method>
Hereinafter, the configuration of the positive electrode will be described. In the present invention, the positive electrode can be manufactured by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. The production of the positive electrode using the positive electrode active material can be performed by a conventional method. That is, a positive electrode active material and a binder, and a conductive material and a thickener, if necessary, are dry-mixed to form a sheet, and the sheet is press-bonded to a positive electrode current collector, or these materials are mixed in a liquid medium. The positive electrode can be obtained by forming a positive electrode active material layer on the current collector by dissolving or dispersing it in a slurry, applying the slurry to a positive electrode current collector, and drying the slurry.

The content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. Within the above range, the electric capacity of the positive electrode active material in the positive electrode active material layer can be secured, and the strength of the positive electrode can be maintained. The positive electrode active material layer obtained by coating and drying is preferably compacted by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is preferably 1.5 g / cm ³ or more, more preferably 2 g / cm ³ , and still more preferably 2.2 g / cm ³ or more as a lower limit, and preferably 5 g / cm ³ or more as an upper limit. ³ or less, more preferably 4.5 g / cm ³ or less, and still more preferably 4 g / cm ³ or less. Within the above range, good charge / discharge characteristics can be obtained, and an increase in electric resistance can be suppressed.

(Conductive material)
As the conductive material, a known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel; graphite (graphite) such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type, and may be used together by arbitrary combinations and ratios by 2 or more types. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. Within the above range, sufficient conductivity and battery capacity can be ensured.

(Binder)
The binder used for producing the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material may be used as long as the material is dissolved or dispersed in a liquid medium used at the time of producing the electrode. Resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber , Butadiene rubber, rubber-like polymers such as ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or hydrogenated product thereof, EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene. Ethylene copolymer, styrene Thermoplastic elastomeric polymer such as isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer Soft resinous polymer such as coalesced polymer; Fluorinated polymer such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer; alkali metal ion (particularly lithium ion )) And a polymer composition having ion conductivity. One of these substances may be used alone, or two or more of them may be used in any combination and in any ratio.

  The proportion of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently held, and the mechanical strength of the positive electrode will be insufficient, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, it may lead to a decrease in battery capacity and conductivity.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as necessary. However, either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone and cyclohexanone; Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) and dimethyl Amides such as formamide and dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide; and the like.

  In particular, when an aqueous medium is used, it is preferable to form a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, but specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio. When a thickener is further added, the ratio of the thickener to the active material is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, The upper limit is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. When the content is in the above range, good coating properties can be obtained, and a decrease in battery capacity and an increase in resistance can be suppressed.

(Current collector)
The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. Among them, a metal material, particularly aluminum is preferable.

  Examples of the shape of the current collector include a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foamed metal in the case of a metal material. Examples include a thin film and a carbon column. Of these, metal thin films are preferred. Note that the thin film may be appropriately formed in a mesh shape. The thickness of the thin film is arbitrary, but from the viewpoint of strength and handleability as a current collector, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and the upper limit is usually 1 mm or less, preferably 100 μm or less. , More preferably 50 μm or less.

It is also preferable that a conductive auxiliary agent is applied to the surface of the current collector from the viewpoint of reducing the electronic contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive additive include carbon and noble metals such as gold, platinum, and silver.
Although the ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, the value of (thickness of the positive electrode active material layer on one side immediately before injection of the electrolytic solution) / (thickness of the current collector) is 20. It is preferably at most 15, more preferably at most 15, most preferably at most 10, and the lower limit is preferably at least 0.5, more preferably at least 0.8, most preferably at least 1. Above this range, the current collector may generate heat due to Joule heat during high current density charging and discharging. Within the above range, heat generation of the current collector during high current density charge / discharge can be suppressed, and battery capacity can be ensured.

(Electrode area)
When the electrolytic solution of the present invention is used, the area of the positive electrode active material layer is preferably larger than the outer surface area of the battery outer case, from the viewpoint of increasing the output and stability at high temperatures. Specifically, the total area of the electrode area of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, more preferably 40 times or more in terms of area ratio. The outer surface area of the outer case, in the case of a bottomed square shape, refers to the total area calculated from the length, width, and thickness dimensions of the case portion filled with the power generating element excluding the terminal protrusions. . In the case of a cylindrical shape with a bottom, the geometrical surface area approximates the cylindrical portion of the case filled with the power generating element excluding the terminal protrusion. The total of the electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in a structure in which the positive electrode mixture layer is formed on both surfaces via the current collector foil. , The sum of the areas for calculating each surface separately.

(Thickness of positive electrode plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer obtained by subtracting the thickness of the metal foil of the core is preferably a lower limit with respect to one surface of the current collector, and is preferably Is 10 μm or more, more preferably 20 μm or more, and the upper limit is preferably 500 μm or less, more preferably 450 μm or less.

(Surface coating of positive electrode plate)
Alternatively, a material in which a substance having a composition different from that of the positive electrode plate is attached to the surface of the positive electrode plate may be used. Examples of surface adhering substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, and calcium sulfate. And carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.

2-3. Separator A separator is usually interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the electrolyte of the present invention is usually used by impregnating the separator.
The material and shape of the separator are not particularly limited, and any known materials can be used as long as the effects of the present invention are not significantly impaired. Among them, a resin, a glass fiber, an inorganic material or the like formed of a stable material for the electrolytic solution of the present invention is used, and it is preferable to use a porous sheet or a non-woven material having excellent liquid retention. .

  As a material of the resin and the glass fiber separator, polyolefin such as polyethylene and polypropylene, aromatic polyamide, polytetrafluoroethylene, polyether sulfone, a glass filter and the like can be used. Among them, glass filters and polyolefins are preferable, and polyolefins are more preferable, and polypropylene is particularly preferable. One of these materials may be used alone, or two or more of them may be used in an optional combination and ratio, or may be used in a laminated form. Specific examples of a laminate of two or more kinds in any combination include a polypropylene, a polyethylene, and a three-layer separator laminated in the order of polypropylene.

The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. When the content is in the above range, the insulating properties and the mechanical strength can be secured, while the battery performance such as rate characteristics and the energy density can be secured.
Further, when a porous material such as a porous sheet or a nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Further, it is usually at most 90%, preferably at most 85%, more preferably at most 75%. When the porosity is in the above range, the insulating property and the mechanical strength can be ensured, but the film resistance can be suppressed and good rate characteristics can be obtained.

  The average pore diameter of the separator is also arbitrary, but is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore diameter exceeds the above range, a short circuit is likely to occur. When the average pore diameter is in the above range, it is possible to suppress short-circuit, suppress film resistance, and obtain good rate characteristics. On the other hand, as the inorganic material, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and particles or fibers are used. .

  As the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. In the case of a thin film, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above independent thin film shape, a separator obtained by forming a composite porous layer containing the above-mentioned inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed on both surfaces of the positive electrode using alumina particles having a 90% particle size of less than 1 μm and a fluororesin as a binder.

2-4. Battery design <Electrode group>
The electrode group has a stacked structure in which the positive electrode plate and the negative electrode plate are interposed with the separator interposed therebetween, and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween. Either may be used. The ratio of the mass of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy) is usually 40% or more, preferably 50% or more, and usually 90% or less, and preferably 80% or less. . When the electrode group occupancy is within the above range, the battery capacity can be ensured, and the deterioration of characteristics such as charge / discharge repetition performance and high-temperature storage due to an increase in internal pressure is suppressed, and further, the operation of the gas release valve is prevented. Can be.

<Current collection structure>
The current collecting structure is not particularly limited, but is preferably a structure that reduces the resistance of the wiring portion and the joining portion. When the electrode group has the above-mentioned laminated structure, a structure formed by bundling the metal core portions of the respective electrode layers and welding them to the terminal is suitably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. In the case where the electrode group has the above-mentioned wound structure, the internal resistance can be reduced by providing a plurality of lead structures on the positive electrode and the negative electrode, respectively, and bundling the terminals.

<Outer case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the nonaqueous electrolyte used. Specifically, a metal such as a nickel-plated steel plate, stainless steel, aluminum or an aluminum alloy, a magnesium alloy, or a laminated film (laminated film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, a metal of aluminum or an aluminum alloy or a laminated film is suitably used.

  In an outer case using metals, a metal is welded to each other by laser welding, resistance welding, ultrasonic welding to form a sealed hermetic structure, or a caulking structure using the above metals via a resin gasket. Things. An outer case using the above-mentioned laminated film includes a case in which a resin layer is heat-sealed to form a sealed structure. In order to enhance the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a hermetically sealed structure, the metal and the resin are joined, so that a resin having a polar group or a polar group introduced as an intervening resin is used. Resins are preferably used. The shape of the exterior body is also arbitrary, and may be, for example, any of a cylindrical shape, a square shape, a laminate type, a coin shape, and a large size.

<Protective element>
As a protection element, PTC (Positive Temperature Coefficient) which increases resistance when abnormal heat or excessive current flows, temperature fuse, thermistor, interrupts current flowing to the circuit due to sudden rise in battery internal pressure or internal temperature during abnormal heat generation (A current cutoff valve) or the like can be used. It is preferable to select a protection element that does not operate under normal use of a high current, and it is more preferable that the protection element be designed not to cause abnormal heat generation or thermal runaway without the protection element.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
The structure of the compound represented by the formula (1) used in this example is shown below.

  The structures of other compounds used are shown below.

<Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-3>
[Example 1-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF _{6 as} an electrolyte is added to a mixed solvent (mixing volume ratio EC: EMC: DEC = 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). Was dissolved at a rate of 1.2 mol / L. Then, 5.0% by mass of monofluoroethylene carbonate was dissolved as an additive to obtain a basic electrolytic solution. Further, 1.0% by mass of the compound (1-1) was added to prepare a non-aqueous electrolyte solution of Example 1-1.

[Preparation of positive electrode]
97% by mass of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was mixed with a disperser to form a slurry. This was uniformly coated on both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to obtain a positive electrode.

[Preparation of negative electrode]
Aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose 1% by mass) as a thickening agent, aqueous dispersion of styrene butadiene rubber (concentration of styrene butadiene rubber 50% by mass) as a binder ) Was added and mixed with a disperser to form a slurry. This slurry was uniformly applied to one surface of a copper foil having a thickness of 10 μm, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that natural graphite: sodium carboxymethylcellulose: styrene butadiene rubber = 98: 1: 1 mass ratio.

[Preparation of non-aqueous electrolyte secondary battery]
The positive electrode, the negative electrode, and the polypropylene separator, the negative electrode, the separator, the positive electrode,
A battery element was fabricated by laminating a separator and a negative electrode in this order. After inserting the battery element into a bag made of a laminated film in which both surfaces of aluminum (40 μm in thickness) are covered with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte is injected into the bag. Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). After that, the battery was charged at a constant current of 0.05 C at 25 ° C. for 6 hours in a state of being pressed between glass plates, and then was discharged at a constant current of 0.2 C to 3.0 V. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, the CC-CV was charged (cut at 0.05 C) to 4.4 V at 0.2 C, and then discharged to 3.0 V at 0.2 C, which was set as an initial 0.2 C capacity. Furthermore, after performing CC-CV charging (0.05 C cut) to 4.4 V at 0.2 C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was defined as the initial gas amount. did.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and for example, 0.2C represents a current value which is 1/5 of that.

[High-temperature storage durability test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before storage was determined from the buoyancy. Thereafter, high-temperature storage was performed at 60 ° C. for 7 days. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as the amount of stored gas.
Using the above-prepared non-aqueous electrolyte secondary battery, initial battery characteristics evaluation and high-temperature storage durability test were performed. Table 1 shows the evaluation results as relative values when Comparative Example 1-1 is set to 100.0%. The same applies to the following.

[Example 1-2]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1-1, except that 3.0% by mass of the compound (1-1) was used in the electrolyte of Example 1-1, and the above evaluation was performed. did.

[Comparative Example 1-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1-1, except that the electrolyte solution containing no compound (1-1) was used in the electrolyte solution of Example 1-1. Carried out.
[Comparative Example 1-2]
Non-aqueous electrolyte secondary battery in the same manner as in Example 1-1, except that in the electrolytic solution of Example 1-1, compound (2-1) was used in an amount of 1.0% by mass instead of compound (1-1). Was prepared, and the above evaluation was performed.

[Comparative Example 1-3]
Non-aqueous electrolyte secondary battery in the same manner as in Example 1-1, except that in the electrolyte of Example 1-1, compound (2-2) was used in an amount of 1.0% by mass instead of compound (1-1). Was prepared, and the above evaluation was performed.

  From Table 1, it can be seen that the use of the non-aqueous electrolytes of Examples 1-1 and 1-2 according to the present invention compared to the case where the compound represented by the formula (1) was not added (Comparative Example 1-1) , With an initial capacity of 0.2 C and a reduced initial gas volume. Also, the amount of stored gas decreases. That is, a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test can be provided.

  When a compound not included in the range of the formula (1) is used (Comparative Examples 1-2 and 1-3), the initial 0.2C capacity decreases and the initial gas amount increases. Further, although the amount of stored gas is smaller than that of Comparative Example 1-1, the effect of improvement is small and is inferior to Examples 1-1 and 1-2. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has more excellent characteristics.

<Examples 2-1 to 2-2 and Comparative example 2-1>
[Example 2-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF _{6 as} an electrolyte is added to a mixed solvent (mixing volume ratio EC: EMC: DEC = 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). Was dissolved at a rate of 1.2 mol / L. Then, 2.0 mass% of vinylene carbonate and 2.0 mass% of monofluoroethylene carbonate were dissolved as additives to prepare a basic electrolyte. Further, 1.37% by mass of the compound (1-1) was added to prepare a non-aqueous electrolyte solution of Example 2-1.

[Preparation of positive electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of negative electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of non-aqueous electrolyte secondary battery]
It was produced in the same manner as in Example 1-1.

[Evaluation of initial battery characteristics]
In a state where the nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressed, at 25 ° C., constant current charging is performed at a current corresponding to 0.05 C for 6 hours, and then constant current discharging is performed at 0.2 C to 3.0 V. Was performed, and the difference between the charge capacity and the discharge capacity at this time was determined, and this was defined as the initial capacity loss. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and for example, 0.2C represents a current value which is 1/5 of that.

[High-temperature storage durability test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before storage was determined from the buoyancy. Thereafter, high-temperature storage was performed at 60 ° C. for 7 days. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as the amount of stored gas. Further, the battery was discharged at a constant current of 0.2 C to 3.0 V at 25 ° C. After that, at 25 ° C., CC-CV charge was performed to 4.4 V with a constant current of 0.2 C (cut at 0.05 C), and then discharged again at 0.2 C to 3.0 V, which was set as a recovered 0.2 C capacity. . Furthermore, after performing CC-CV charging (0.05C cut) to 4.4V at 0.2C, it was discharged to 3.0V at 0.5C, and this was made into 0.5C recovery capacity. Then, the ratio of the recovered 0.5C capacity to the recovered 0.2C capacity was determined, and this was defined as the post-storage rate characteristic (%).
Using the above-prepared non-aqueous electrolyte secondary battery, initial battery characteristics evaluation and high-temperature storage durability test were performed. Table 2 shows the evaluation results as relative values when Comparative Example 2-1 is set to 100.0%. The same applies to the following.

[Example 2-2]
Non-aqueous electrolyte secondary battery in the same manner as in Example 2-1 except that 1.86% by mass of compound (1-2) was used instead of compound (1-1) in the electrolyte of Example 2-1. Was prepared, and the above evaluation was performed. In addition, the compound (1-1) added in Example 2-1 and the compound (1-2) added in Example 2-2 are equivalent substance amounts.

[Comparative Example 2-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 2-1 except that the electrolyte solution containing no compound (1-1) was used in the electrolyte solution of Example 2-1. Carried out.

From Table 2, it can be seen that the use of the non-aqueous electrolyte of Example 2-1 according to the present invention resulted in an initial capacity loss compared to the case where the compound represented by the formula (1) was not added (Comparative Example 2-1). Decrease. Further, the amount of stored gas is reduced, and the rate characteristics after storage are improved. That is, a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test can be provided.
In addition, when the non-aqueous electrolyte solution of Example 2-2 according to the present invention is used, the initial capacity loss increases compared to the case where the compound represented by Formula (1) is not added (Comparative Example 2-1). Is not seen. In addition, the amount of storage gas decreases, and the rate characteristics after storage improve. That is, a battery having excellent battery characteristics after the high-temperature storage durability test can be provided.

<Example 3-1 and Comparative example 3-1>
[Example 3-1]
[Preparation of non-aqueous electrolyte]
Under dry argon atmosphere, ethylene carbonate (EC), ethyl propionate (EP)
LiPF ₆ as an electrolyte was dissolved at a ratio of 1.2 mol / L in a mixed solvent (mixed volume ratio EC: EP: DEC = 3: 4: 3) composed of dimethyl ether and diethyl carbonate (DEC). Then, 5.0% by mass of monofluoroethylene carbonate and 2.0% by mass of 1,3-propane sultone were dissolved as additives to prepare a basic electrolyte. Further, the non-aqueous electrolyte solution of Example 3-1 was prepared by adding 0.5% by mass of the compound (1-1).

[Preparation of positive electrode]
It was produced in the same manner as in Example 1-1.
[Preparation of negative electrode]
It was produced in the same manner as in Example 1-1.
[Preparation of non-aqueous electrolyte secondary battery]
It was produced in the same manner as in Example 1-1.

The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). After that, the battery was charged at a constant current of 0.05 C at 25 ° C. for 6 hours in a state of being pressed between glass plates, and then was discharged at a constant current of 0.2 C to 3.0 V. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, the CC-CV was charged (cut at 0.05 C) to 4.4 V at 0.2 C, and then discharged to 3.0 V at 0.2 C, which was set as an initial 0.2 C capacity. Furthermore, after performing CC-CV charging (0.05 C cut) to 4.4 V at 0.2 C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was defined as the initial gas amount. did.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and for example, 0.2C represents a current value which is 1/5 of that.

[High-temperature storage durability test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before storage was determined from the buoyancy. Thereafter, high-temperature storage was performed at 60 ° C. for 7 days. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as the amount of stored gas. Further, the open circuit voltage (OCV) of the battery was measured, and this was taken as OCV after storage.

The OCV of the battery after the high-temperature storage durability test mainly reflects the potential of the positive electrode. That is, when the OCV after storage is low, it indicates that the oxidation side reaction on the positive electrode during the high-temperature storage test has significantly progressed. Normally, when the oxidation side reaction proceeds on the positive electrode, metal elution from the positive electrode is accelerated, and the positive electrode itself is deteriorated. Therefore, the higher the OCV after storage, the better the battery characteristics after the high-temperature storage durability test can be provided.
Using the above-prepared non-aqueous electrolyte secondary battery, initial battery characteristics evaluation and high-temperature storage durability test were performed. Table 3 shows the evaluation results as relative values when Comparative Example 3-1 is set to 100.0%. Note that the OCV after storage is a value obtained by subtracting the value of Comparative Example 3-1 from the value of Example 3-1 in the column of Example 3-1. Shown by the difference. The same applies to the following.

[Comparative Example 3-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 3-1 except that the electrolyte of Example 3-1 did not contain the compound (1-1). Carried out.

  From Table 3, it can be seen that the use of the non-aqueous electrolyte of Example 3-1 according to the present invention resulted in an initial increase of 0.1 in comparison with the case where the compound represented by the formula (1) was not added (Comparative Example 3-1). It is excellent in 2C capacity and the initial gas amount is reduced. Also, the amount of stored gas is reduced, and the OCV after storage is high. That is, a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test can be provided.

<Example 4-1 and Comparative example 4-1>
[Example 4-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF _{6 as} an electrolyte is added to a mixed solvent (mixing volume ratio EC: EP: DEC = 3: 4: 3) composed of ethylene carbonate (EC), ethyl propionate (EP), and diethyl carbonate (DEC). Was dissolved at a rate of 1.2 mol / L. As additives, 5.0% by mass of monofluoroethylene carbonate, 2.0% by mass of 1,3-propane sultone, 3.0% by mass of succinonitrile and 0.5% by mass of 1-propene-1,3-sultone Was dissolved to obtain a basic electrolytic solution. Further, 0.5% by mass of the compound (1-1) was added to prepare a non-aqueous electrolyte solution of Example 4-1.

[Preparation of positive electrode]
It was produced in the same manner as in Example 1-1.
[Preparation of negative electrode]
It was produced in the same manner as in Example 1-1.
[Preparation of non-aqueous electrolyte secondary battery]
It was produced in the same manner as in Example 1-1.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by sandwiching between glass plates, constant-current charging was performed at 25 ° C. at a current corresponding to 0.05 C for 6 hours, and then constant-current discharging was performed at 0.2 C to 3.0 V. The difference between the charge capacity and the discharge capacity was determined, and this was defined as the initial capacity loss. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, the CC-CV was charged (cut at 0.05 C) to 4.4 V at 0.2 C, and then discharged to 3.0 V at 0.2 C, which was set as an initial 0.2 C capacity. Furthermore, after performing CC-CV charging (0.05 C cut) to 4.4 V at 0.2 C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was defined as the initial gas amount. did.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and for example, 0.2C represents a current value which is 1/5 of that.

[High-temperature storage durability test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before storage was determined from the buoyancy. Thereafter, high-temperature storage was performed at 60 ° C. for 7 days. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as the amount of stored gas. Further, the open circuit voltage (OCV) of the battery was measured, and this was taken as OCV after storage.

The OCV of the battery after the high-temperature storage durability test mainly reflects the potential of the positive electrode. That is, when the OCV after storage is low, it indicates that the oxidation side reaction on the positive electrode during the high-temperature storage test has significantly progressed. Normally, when the oxidation side reaction proceeds on the positive electrode, metal elution from the positive electrode is accelerated, and the positive electrode itself is deteriorated. Therefore, the higher the OCV after storage, the better the battery characteristics after the high-temperature storage durability test can be provided.
Using the above-prepared non-aqueous electrolyte secondary battery, initial battery characteristics evaluation and high-temperature storage durability test evaluation were performed. Table 4 shows the evaluation results as relative values when Comparative Example 4-1 is set to 100.0%. Note that the OCV after storage is a value obtained by subtracting the value of Comparative Example 4-1 from the value of Example 4-1 in the column of Example 4-1. Shown by the difference. The same applies to the following.

[Comparative Example 4-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 4-1 except that the electrolyte solution containing no compound (1-1) was used in the electrolyte solution of Example 4-1 and the above evaluation was performed. did.

  Table 4 shows that the use of the non-aqueous electrolyte of Example 4-1 according to the present invention resulted in an initial capacity loss as compared with the case where the compound represented by the formula (1) was not added (Comparative Example 4-1). And the initial gas amount decreases. Also, the amount of stored gas is reduced, and the OCV after storage is high. That is, a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test can be provided.

<Example 5-1 and Comparative Examples 5-1 to 5-2>
[Example 5-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF _{6 as} an electrolyte is added to a mixed solvent (mixing volume ratio EC: EMC: DEC = 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). Was dissolved at a rate of 1.2 mol / L. Then, 2.0 mass% of vinylene carbonate and 2.0 mass% of monofluoroethylene carbonate were dissolved as additives to prepare a basic electrolyte. Further, 1.0% by mass of the compound (1-1) was added to prepare a non-aqueous electrolyte solution of Example 5-1.

[Preparation of positive electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of negative electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of non-aqueous electrolyte secondary battery]
It was produced in the same manner as in Example 1-1.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). After that, the battery was charged at a constant current of 0.05 C at 25 ° C. for 6 hours in a state of being pressed between glass plates, and then was discharged at a constant current of 0.2 C to 3.0 V. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, the CC-CV was charged (cut at 0.05 C) to 4.4 V at 0.2 C, and then discharged to 3.0 V at 0.2 C, which was set as an initial 0.2 C capacity. Furthermore, after performing CC-CV charging (0.05 C cut) to 4.4 V at 0.2 C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was defined as the initial gas amount. did.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and for example, 0.2C represents a current value which is 1/5 of that.

[High-temperature storage durability test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before storage was determined from the buoyancy. Thereafter, high-temperature storage was performed at 85 ° C. for one day. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the change from the battery volume before storage was defined as the amount of stored gas.
Using the above-prepared non-aqueous electrolyte secondary battery, initial battery characteristics evaluation and high-temperature storage durability test were performed. Table 5 shows the evaluation results as relative values when Comparative Example 5-1 is set to 100.0%. The same applies to the following.

[Comparative Example 5-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 5-1 except that the electrolyte solution containing no compound (1-1) was used in the electrolyte solution of Example 5-1. Carried out.

[Comparative Example 5-2]
Non-aqueous electrolyte secondary battery in the same manner as in Example 5-1 except that 1.0% by mass of compound (2-3) was used instead of compound (1-1) in the electrolyte of Example 5-1. Was prepared, and the above evaluation was performed.

From Table 5, it can be seen that the use of the non-aqueous electrolyte of Example 5-1 according to the present invention resulted in an initial increase of 0.1 in comparison with the case where the compound represented by the formula (1) was not added (Comparative Example 5-1). It is excellent in 2C capacity and the initial gas amount is reduced. Also, the amount of stored gas decreases. That is, a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test can be provided.

When a compound that is not included in the range of the formula (1) is used (Comparative Example 5-2), the initial 0.2 C capacity decreases and the initial gas amount increases. Further, the amount of stored gas increases. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has more excellent characteristics.
<Example 6-1 and Comparative Examples 6-1 to 6-2>
[Example 6-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF _{6 as} an electrolyte is added to a mixed solvent (mixing volume ratio EC: EMC: DEC = 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). Was dissolved at a rate of 1.2 mol / L. Then, 2.0 mass% of vinylene carbonate and 2.0 mass% of monofluoroethylene carbonate were dissolved as additives to prepare a basic electrolyte. Further, 0.5% by mass of the compound (1-1) was added to prepare a non-aqueous electrolyte solution of Example 6-1.

[Preparation of positive electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of negative electrode]
It was produced in the same manner as in Example 1-1.

[Preparation of non-aqueous electrolyte secondary battery]
It was produced in the same manner as in Example 1-1.

[Early battery characteristics evaluation]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). After that, the battery was charged at a constant current of 0.05 C at 25 ° C. for 6 hours in a state of being pressed between glass plates, and then was discharged at a constant current of 0.2 C to 3.0 V. Further, after constant current-constant voltage charging (also referred to as “CC-CV charging”) (cutting 0.05 C) to 4.1 V with a current corresponding to 0.2 C, the mixture was left at 45 ° C. for 72 hours. . Thereafter, the battery was discharged to 3.0 V at a constant current of 0.2 C. Next, after performing CC-CV charging (cutting 0.05 C) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, the CC-CV was charged (cut at 0.05 C) to 4.4 V at 0.2 C, and then discharged to 3.0 V at 0.2 C, which was set as an initial 0.2 C capacity. Furthermore, after performing CC-CV charging (0.05 C cut) to 4.4 V at 0.2 C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was defined as the initial gas amount. did.
Here, 1C represents a current value at which the reference capacity of the battery is discharged in one hour, and, for example, 0.2C represents a current value which is 1/5 of that.

[Continuous charging endurance test]
The non-aqueous electrolyte secondary battery after the initial battery characteristic evaluation was CC-CV charged (cut at 0.05 C) to 0.2 V and 4.4 V at 25 ° C., and then immersed in an ethanol bath. The battery volume before the continuous charge durability test was determined from the buoyancy. Thereafter, constant current-constant voltage charging of 4.4 V at 0.2 C at 60 ° C. was performed for 168 hours. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the amount of change from the battery volume before the continuous charge durability test was defined as the continuously charged gas amount. Thereafter, the battery was discharged at a constant current of 0.2 C to 3.0 V, which was defined as a remaining capacity.
Using the non-aqueous electrolyte secondary battery produced above, an initial battery characteristic evaluation and a continuous charge durability test were performed. Table 6 shows the evaluation results as relative values when Comparative Example 6-1 is set to 100.0%. The same applies to the following.

[Comparative Example 6-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 6-1 except that an electrolyte containing no compound (1-1) was used in the electrolyte of Example 6-1. Carried out.

[Comparative Example 6-2]
Nonaqueous electrolyte secondary battery in the same manner as in Example 6-1 except that 0.45% by mass of compound (2-4) was used instead of compound (1-1) in the electrolyte solution of Example 6-1. Was prepared, and the above evaluation was performed. In addition, the compound (1-1) added in Example 6-1 and the compound (2-4) added in Comparative Example 6-2 are equivalent substance amounts.

  From Table 6, it can be seen that the use of the non-aqueous electrolyte of Example 6-1 according to the present invention resulted in an initial increase of 0.1 in comparison with the case where the compound represented by the formula (1) was not added (Comparative Example 6-1). It is excellent in 2C capacity and the initial gas amount is reduced. In addition, the amount of continuously charged gas is reduced, and the remaining capacity is excellent. That is, a battery having excellent initial battery characteristics and excellent battery characteristics after a continuous charge durability test can be provided.

  When a compound that is not included in the range of the formula (1) is used (Comparative Example 6-2), the initial 0.2 C capacity decreases. Further, the amount of continuously charged gas increases, and the remaining capacity also decreases. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has more excellent characteristics.

  According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery capable of providing a non-aqueous electrolyte secondary battery having excellent initial battery characteristics and excellent battery characteristics after a durability test, and a non-aqueous electrolyte secondary battery , High performance and high safety can be achieved. The non-aqueous electrolyte and the non-aqueous electrolyte secondary battery of the present invention can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copies, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. , Electronic organizer, calculator, memory card, portable tape recorder, radio, backup power supply, motor, car, motorcycle, motorbike, bicycle, lighting equipment, toy, game equipment, clock, power tool, strobe, camera, load leveling Power source, natural energy storage power source, lithium ion capacitor and the like.

Claims (6)

A non-aqueous electrolyte for a non-aqueous electrolyte secondary battery including a positive electrode and a negative electrode capable of inserting and extracting metal ions, wherein the non-aqueous electrolyte is represented by the formula (1) together with an electrolyte and a non-aqueous solvent. A non-aqueous electrolyte solution comprising a compound in an amount of 0.001% by mass or more and 10% by mass or less .

(Where
R ¹ is a hydrogen atom, a fluorine atom or a carbon atom of 1 or more 1 which may be substituted with a fluorine atom.
R ² and R ³ are each independently a hydrogen atom, a fluorine atom or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent; ^A ring may be formed by at least two of ¹ , R ² and R ³ ;
n is an integer of 1 or more and 12 or less . However, when n is 2 or more, a plurality of R ² and R ³ may be the same or different. )   The non-aqueous electrolyte according to claim 1, wherein in the formula (1), n is an integer of 2 or more. The non-aqueous electrolyte according to claim 1, wherein n is an integer of 6 or less. The non-aqueous electrolyte further includes a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphorus-containing organic compound, an organic compound having a cyano group other than the formula (1), an organic compound having an isocyanate group, a silicon-containing compound, and an aromatic compound. Group compound, cyclic carbonate having carbon-carbon unsaturated bond, fluorine-free carboxylic acid ester, cyclic compound having plural ether bonds, compound having isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, boric acid At least one selected from the group consisting of salts, oxalates and fluorosulfonates
The non-aqueous electrolyte solution according to any one of claims 1 to 3, which contains a kind of compound. The fluorine-containing cyclic carbonate, the sulfur-containing organic compound, the phosphorus-containing organic compound, the organic compound having a cyano group other than the formula (1), the organic compound having an isocyanate group, the silicon-containing compound, the aromatic compound, and the carbon-carbon unsaturated. Cyclic carbonate having a bond, fluorine-free carboxylic acid ester, cyclic compound having a plurality of ether bonds, compound having an isocyanuric acid skeleton, monofluorophosphate, difluorophosphate, borate, oxalate, and fluorosulfone The non-aqueous electrolyte according to claim 4, wherein the total content of at least one compound selected from the group consisting of acid salts with respect to the total amount of the non-aqueous electrolyte is from 0.001% by mass to 30% by mass. A non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte is any of claims 1 to 5 . A non-aqueous electrolyte secondary battery according to claim 1.