JP6759847B2 - Non-aqueous electrolyte solution and non-aqueous electrolyte battery using it - Google Patents

Description

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

With the rapid progress of portable electronic devices such as mobile phones and notebook personal computers, there is an increasing demand for higher capacity batteries used for their main power supply and backup power supply, and nickel-cadmium batteries and nickel-cadmium batteries Non-aqueous electrolyte batteries such as lithium-ion secondary batteries, which have a higher energy density than hydrogen batteries, are attracting attention.
As the electrolytic solution of the 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, and a high dielectric constant such as ethylene carbonate or propylene carbonate is used. A typical example is a non-aqueous electrolyte solution dissolved in a mixed solvent of a solvent and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

Further, as the negative electrode active material of the 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 mentioned as typical examples. Be done. Metal or alloy-based negative electrodes using silicon, tin, or the like are also known with the aim of further increasing the capacity. As the positive electrode active material, a transition metal composite oxide capable of occluding and releasing lithium ions is mainly used, and typical examples of the transition metal include cobalt, nickel, manganese, iron and the like.

In a non-aqueous electrolyte secondary battery using such a non-aqueous electrolyte, the reactivity differs depending on the composition of the non-aqueous electrolyte, so that the battery characteristics greatly change depending on the non-aqueous electrolyte. Various studies have been conducted on non-aqueous solvents and electrolytes in order to improve battery characteristics such as storage characteristics of non-aqueous electrolyte secondary batteries and to improve battery safety during overcharging.

Patent Document 1 describes a specific aromatic ester in an electrolytic solution in a lithium secondary battery composed of a positive electrode using lithium cobalt oxide as an active material, a negative electrode using graphite as an active material, a separator, and a non-aqueous electrolytic solution. Studies have been made to improve gas generation during high-temperature storage by adding a compound.

Patent Document 2 describes a lithium secondary battery including a positive electrode using a lithium transition metal oxide typified by lithium cobalt oxide as an active material, a negative electrode using carbon as an active material, a separator, and a non-aqueous electrolyte solution. Studies have been made to improve the amount of gas and overcharge characteristics after initial conditioning by adding a specific aromatic carboxylic acid ester to the electrolytic solution.

Japanese Unexamined Patent Publication No. 2003-243026 Japanese Unexamined Patent Publication No. 2015-159109

However, in recent years, there has been an increasing demand for improving the characteristics of lithium non-aqueous electrolyte secondary batteries. There is a trade-off between durability such as high-temperature storage characteristics and battery performance such as oxidation resistance, capacity, resistance, and output characteristics, and there is a problem that the overall performance is unbalanced.

Patent Document 1 clarifies that the amount of gas generated during high-temperature storage can be suppressed by using an electrolytic solution containing a specific aromatic ester compound. Patent Document 2 clarifies that the amount of gas and overcharge characteristics after initial conditioning can be improved by using an electrolytic solution containing a specific aromatic carboxylic acid ester. However, with the recent increase in the operating voltage of batteries, there is an increasing demand for gas suppression, especially during full charge and high temperature storage.

The present invention has been made in view of the above-mentioned problems. That is, it is an object of the present invention to provide a non-aqueous electrolyte battery and a non-aqueous electrolyte battery which suppress gas generation at the time of full charge and high temperature storage and have excellent electrochemical oxidation resistance in the non-aqueous electrolyte battery.

As a result of diligent studies, the present inventors have conducted a non-aqueous electrolyte solution for a non-aqueous electrolyte battery, and the non-aqueous electrolyte solution contains a specific compound in the electrolytic solution together with an alkali metal salt and a non-aqueous solvent. It has been found that the above problems can be solved by using a non-aqueous electrolyte solution characterized by containing the above-mentioned problem, and the present invention has been completed.

The gist of the present invention is as shown below.
[1] Non-aqueous electrolyte solution A non-aqueous electrolyte solution for a battery, characterized in that the non-aqueous electrolyte solution contains a compound represented by the formula (A) together with an alkali metal salt and a non-aqueous solvent. Aqueous electrolyte.
(In the formula (A), R ^{1 to} R ³ represent hydrocarbon groups having 1 to 20 carbon atoms which may independently have a hydrogen atom or a substituent, and are among R ^{1 to} R ³ . , At least one represents a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. X represents a hydrocarbon group having 1 to 10 carbon atoms. A represents an integer of 1 to 5. )
[2] The non-aqueous electrolyte solution according to [1], wherein X is a methyl group in the formula (A).
[3] The non-aqueous electrolyte solution according to [1] or [2], wherein a is 1 or 2 in the formula (A).
[4] In the formula (A), at least one of R ^{1 to} R ³ is an aryl group having 6 to 20 carbon atoms which may have a substituent, according to [1] to [3]. The non-aqueous electrolyte solution according to any one. [5] Any of [1] to [4], wherein the content of the compound represented by the formula (A) is 0.001% by mass or more and 10% by mass or less with respect to the total amount of the non-aqueous electrolyte solution. The non-aqueous electrolyte solution described in 1.
[6] Further, a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, an isocyanate compound, a compound having an isocyanuric acid skeleton, a fluorinated salt, a cyclic ether compound, an oxalate salt and a cyclic sulfone. The non-aqueous electrolyte solution according to any one of [1] to [5], which contains at least one compound selected from the group consisting of acid esters.
[7] The non-aqueous electrolyte solution according to any one of [1] to [6], wherein the non-aqueous solvent contains a chain carboxylic acid ester.
[8] In a non-aqueous electrolyte secondary battery including a positive electrode capable of storing and releasing lithium ions, a negative electrode capable of storing and releasing lithium ions, and a non-aqueous electrolyte solution, the non-aqueous electrolyte solution is [1]. ] To [7], the non-aqueous electrolyte secondary battery, which is the non-aqueous electrolyte solution.
[9] An electric vehicle equipped with the non-aqueous electrolyte secondary battery according to [8] as a power source.

According to one embodiment of the present invention, the lithium non-aqueous electrolyte secondary battery suppresses gas generation during full charge and high temperature storage, and has excellent electrochemical oxidation resistance, durability and electrochemical characteristics. It is possible to provide a well-balanced battery.
When the non-aqueous electrolyte secondary battery produced by using the non-aqueous electrolyte solution according to the embodiment of the present invention and the non-aqueous electrolyte secondary battery according to the embodiment of the present invention are fully charged and stored at a high temperature. Although the action / principle of suppressing the generation of gas and improving the electrochemical oxidation resistance is not clear, it is considered as follows. However, the present invention is not limited to the actions / principles described below.

The compound represented by the formula (A) has an aromatic ring in which the hydrocarbon group, which is an easily oxidizing site, is substituted in the molecule. Therefore, the above-mentioned hydrocarbon group undergoes an oxidation reaction on the positive electrode to generate radical species or cation species, and a film is formed on the positive electrode. Since this film has insulating properties, it suppresses decomposition of salts, solvents, and other auxiliaries, which are constituents of the electrolytic solution, due to the oxidation reaction. Further, in the compound represented by the formula (A), since at least one of α-hydrogens is substituted with a hydrocarbon group, the reduction reactivity at the negative electrode is suppressed. As a result, the proportion of the compound represented by the formula (A) concentrated on the surface of the positive electrode increases, and it is considered that a film can be efficiently formed on the positive electrode. It is estimated that this has a high effect of improving the high temperature storage characteristics and contributes to the protection of the positive electrode.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

1. 1. Non-aqueous electrolyte 1-1. Non-Aqueous Electrolyte Solution of the Present Invention The non-aqueous electrolyte solution according to the embodiment of the present invention is characterized by containing a compound represented by the formula (A).

1-1-1. Compound represented by formula (A)

In the formula (A), R ^{1 to} R ³ represent hydrocarbon groups having 1 to 20 carbon atoms which may independently have hydrogen atoms or substituents, and among R ^{1 to} R ³ , At least one represents a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. X represents a hydrocarbon group having 1 to 10 carbon atoms. a represents an integer of 1 to 5.

Here, as the substituent, a cyano group, an isocyanato group, an acyl group (-(C = O) -Ra), an acyloxy group (-O (C = O) -Ra), an alkoxycarbonyl group (-(C =)) O) O-Ra), sulfonyl group (-SO ₂ -Ra), sulfonyloxy group (-O (SO ₂ ) -Ra), alkoxysulfonyl group (-(SO ₂ ) -O-Ra), alkoxycarbonyloxy group (-O- (C = O) -O-Ra), ether group (-O-Ra), acrylic group, methacryl group, halogen (preferably fluorine), trifluoromethyl group and the like can be mentioned. In addition, Ra represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms. The carbon in these substituents is not counted in the number of carbons in the hydrocarbon groups having 1 to 20 carbon atoms of R ¹ , R ² and R ³ .

Specific examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. Among them, an alkyl group, an alkenyl group and an aryl group are preferable, an alkyl group and an aryl group are more preferable, and an alkyl group is particularly preferable. Of these, an aryl group having 6 to 20 carbon atoms is preferable, and an aryl group having 6 to 10 carbon atoms is more preferable. In the present invention, the phenyl group bonded via the alkylene group is also included in the aryl group, and the carbon number of the alkylene group is also included in the carbon number of the aryl group.
With the above-mentioned hydrocarbon group, it is possible to prevent the compound represented by the formula (A) from reacting with the decomposition product of the electrolytic solution and suppressing the resistance from increasing too much.
Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, i-butyl group, t-butyl group, n-pentyl group, and the like. Examples thereof include t-amyl group, hexyl group, heptyl group, octyl group, nonyl group and decyl group. Of these, methyl group, ethyl group, i-propyl group, n-propyl group, n-butyl group, n-pentyl group and hexyl group are preferable, and methyl group, ethyl group and i-propyl group are more preferable. Examples include a group, an n-propyl group, and an n-butyl group. A methyl group and an ethyl group are most preferable because an increase in the viscosity of the electrolytic solution due to the addition of the compound is suppressed.
Specific examples of the alkenyl group include a vinyl group, an allyl group, a metallicyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, a 3-butenyl group, a 4-pentenyl group and the like. Among these, a vinyl group, an allyl group, a metalyl group, and a 2-butenyl group are preferable, a vinyl group, an allyl group, and a metalyl group are more preferable, and an allyl group and a metalyl group are particularly preferable. It is preferably an allyl group. This is because the above-mentioned alkenyl group is suitable for steric hindrance.
Specific examples of the alkynyl group include an ethynyl group, a 2-propynyl group, a 2-butynyl group, a 3-butynyl group, a 4-pentynyl group, a 5-hexynyl group and the like. Among these, an ethynyl group, a 2-propynyl group, a 2-butynyl group and a 3-butynyl group are preferable, a 2-propynyl group and a 3-butynyl group are more preferable, and a 2-propynyl group is particularly preferable. Is. This is because the above-mentioned alkynyl group is suitable for steric hindrance.
Specific examples of the aryl group include a phenyl group, a phenyl group bonded via an alkylene group (for example, a benzyl group, a phenethyl group, etc.), a tolyl group, a xsilyl group, and the like. Among these, a phenyl group and a tolyl group bonded via a phenyl group and an alkylene group are preferable, and a phenyl group bonded via a phenyl group and an alkylene group are more preferable, and a phenyl group is particularly preferable. Is. This is because the above-mentioned aryl group is suitable for steric hindrance.

From the viewpoint of reactivity between the compound represented by the formula (A) and the electrode, X is preferably a methyl group.

In the formula (A), a is preferably 1 or 2. It is possible to prevent the compound represented by the formula (A) from reacting with the decomposition product of the electrolytic solution and suppressing the resistance from increasing too much.

Specific examples of the compound represented by the formula (A) include compounds having the following structures.

As the compound represented by the formula (A), a compound having the following structure is preferable. These can suitably control the resistance of the coating film formed on the positive electrode.

More preferably, a compound having the following structure can be mentioned as the compound represented by the formula (A). The molecular size of the compound is suitable for these, and they can react efficiently on the positive electrode.

The compound represented by the formula (A) is more preferably a compound having the following structure. The oxidation reactivity on the positive electrode can be suitably controlled.

As the compound represented by the formula (A), a compound having the following structure is particularly preferable. These are preferable because they have a high effect of suppressing side reactions on the positive electrode.

The compound represented by the formula (A) is most preferably a compound having the following structure. These compounds can suitably form an insulating film on the positive electrode.

The content of the compound represented by the formula (A) with respect to the total amount of the non-aqueous electrolyte solution is not limited and is arbitrary as long as the effect of the present invention is exhibited, but is usually 0 with respect to the total amount of the non-aqueous electrolyte solution of the present invention. .001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less. It is blended in the electrolytic solution at a concentration of 4% by mass or less, more preferably 3% by mass or less. With the above concentration, the reaction frequency and reactivity on the electrode can be suitably adjusted, and the battery characteristics can be optimized. The compound represented by the formula (A) may be used alone or in combination of two or more.

When the content of the compound represented by the formula (A) satisfies the above range, gas generation during full charge and high temperature storage is suppressed, and the electrochemical oxidation resistance is further improved.

The method of blending the compound represented by the formula (A) with the electrolytic solution 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 an electrolytic solution can be mentioned. Examples of the 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 electrolytic solution is oxidized, reduced, hydrolyzed or the like to be generated. Further, a method of producing a battery and generating it by applying an electric load such as charging / discharging can be mentioned.

1-2. Consists of cyclic carbonate having a carbon-carbon unsaturated bond, cyclic carbonate having a fluorine atom, nitrile compound, isocyanate compound, compound having an isocyanuric acid skeleton, fluorinated salt, cyclic ether compound, oxalate salt and cyclic sulfonic acid ester. At least one specific compound selected from the group, or a chain carboxylic acid ester The non-aqueous electrolyte solution according to the embodiment of the present invention contains a carbon-carbon unsaturated bond in addition to the compound represented by the formula (A). From cyclic carbonates having, cyclic carbonates having fluorine atoms, cyclic carbonates having fluorine atoms, nitrile compounds, isocyanate compounds, compounds having isocyanuric acid skeletons, fluorinated salts, cyclic ether compounds, oxalate salts and cyclic sulfonic acid esters. It is preferable to further contain at least one specific compound selected from the above group or a chain carboxylic acid ester from the viewpoint of improving battery characteristics.

Among these, from the viewpoint of improving battery characteristics, a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic ether compound, a compound having an isocyanuric acid skeleton, a cyclic sulfonic acid ester, and a chain carboxylic compound. Acid esters are more preferred, cyclic carbonates with carbon-carbon unsaturated bonds, cyclic carbonates with fluorine atoms, nitrile compounds, cyclic ether compounds, cyclic sulfonic acid esters, and chain carboxylic acid esters are even more preferred, and carbon-carbon unsaturated. A cyclic carbonate having a bond, a cyclic carbonate having a fluorine atom, a nitrile compound, and a chain carboxylic acid ester are particularly preferable, and a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom are most preferable.

The compound represented by the formula (A) undergoes an oxidation reaction on the active material of the electrode to form a cation (electrophile) in the structure. On the other hand, since the specific compound has an electrophilic attack receiving site in its molecular structure, a complex film is formed by reacting with the specific compound and the oxidation product of the compound represented by the formula (A). It is speculated.

As described above, it is presumed that by co-adding these specific compounds and the compound represented by the formula (A) to the non-aqueous electrolytic solution, they react with each other on the electrodes to form a complex film. Therefore, the oxidation reaction of the non-aqueous electrolyte solution on the positive electrode surface is further suppressed as compared with the case where each compound is added to the non-aqueous electrolyte solution alone, so that the battery characteristics are improved. Hereinafter, the above-mentioned specific compound will be described individually.

1-2-1. Cyclic carbonate having a carbon-carbon unsaturated bond The non-aqueous electrolyte solution according to the embodiment of the present invention further contains a cyclic carbonate having a carbon-carbon unsaturated bond in addition to the compound represented by the formula (A). It is preferable from the viewpoint of improving the battery characteristics.
The cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter, may be referred to as “unsaturated cyclic carbonate”) is particularly a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond. There is no limit. Any unsaturated carbonate can be used as the unsaturated cyclic carbonate. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate. Further, the unsaturated cyclic carbonate may have a fluorine atom (also referred to as a fluorinated unsaturated carbonate), in which case the fluorine atom is usually 6 or less, preferably 4 or less, and 1 or 2. Most preferably.

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, etc. Examples thereof include catechol carbonates.

As the vinylene carbonates,
Vinylene carbonate, methyl vinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate , 4-Fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene 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-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-dietinylethylene carbonate, 4-methyl-5 -Ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene 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-allylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4 -Fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-5-vinylethylene carbonate, 4,4-difluoro-5-allylethylene carbonate, 4,5-difluoro-4 -Vinyl ethylene 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 and the like.

Among the above, the preferred unsaturated cyclic carbonate is
Vinylene carbonate, methyl vinylene carbonate, 4,5-dimethylvinylene 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-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5 -Diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene 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-5-vinylethylene carbonate, 4,4-difluoro-5-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 Examples include carbonate.

Further, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are particularly preferable because they form a particularly stable interfacial protective film.

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 and 250 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolyte solution can be easily ensured, and the effect of the present invention can be sufficiently exhibited. The molecular weight of the unsaturated cyclic carbonate is more preferably 85 or more, and more preferably 150 or less.

The method for producing the unsaturated cyclic carbonate described above is not particularly limited, and a known method can be arbitrarily selected for production.

In the non-aqueous electrolyte solution, one type of unsaturated cyclic carbonate may be used alone, or two or more types may be used in any combination and ratio. The content 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 content 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 0.5% by mass or more in 100% by mass of the non-aqueous electrolyte solution. It is particularly preferably 1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

1-2-2. Cyclic carbonate having a fluorine atom The non-aqueous electrolyte solution according to the embodiment of the present invention further contains a cyclic carbonate having a fluorine atom in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics. preferable.
Examples of the cyclic carbonate having a fluorine atom, which is a kind of a specific compound, include a fluoride of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms and a derivative thereof. Examples thereof include fluorinated products of ethylene carbonate and derivatives thereof. Examples of the derivative of the fluorinated product of ethylene carbonate include a fluorinated product of ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). As the cyclic carbonate having a fluorine atom, an ethylene carbonate having 1 to 8 fluorine atoms and a derivative thereof are preferable. Regarding the cyclic carbonate (fluorinated unsaturated carbonate) having a fluorine atom and an unsaturated bond, the above 1-2-1. It is described in.

As a concrete example of them,
Monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methyl Ethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) Methyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4, Examples thereof include 4-difluoro-5,5-dimethylethylene carbonate and the like.

Among these, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate and 4,5-difluoroethylene carbonate imparts high ionic conductivity and preferably forms an interface protection film. It is more preferable in that it does.

As the cyclic carbonate having a fluorine atom, one type may be used alone, or two or more types may be used in combination in any combination and ratio.

The content of the cyclic carbonate having a fluorine atom in the entire non-aqueous electrolyte solution of the present invention is not limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content 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 0.5% by mass or more in 100% by mass of the non-aqueous electrolyte solution. It is particularly preferably 1% by mass or more, and usually 10% by mass or less, preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less. However, monofluoroethylene carbonate may be used as a solvent, and in that case, the content is not limited to the above.

1-2-3. Nitrile Compound The non-aqueous electrolyte solution according to the embodiment of the present invention preferably contains a nitrile compound in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
The type of the nitrile compound, which is one of the specific compounds, is not particularly limited as long as it is a compound having a cyano group in the molecule.

Specific examples of the nitrile compound include, for example.
Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, decanenitrile, lauronitrile, 2-methylbutyronitrile, trimethylnitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, Methacronitrile, Crotononitrile, 3-Methylcrotononitrile, 2-Methyl-2-butenenitrile, 2-Pentenenitrile, 2-Methyl-2-Pentenenitrile, 3-Methyl-2-Pentenenitrile, 2-Hexen Nitrile, Fluoroaceton, Difluoroacetonitrile, Trifluoronitrile, 2-Fluoropropionitrile, 3-Fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropro Compounds having one nitrile group such as pionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, pentafluoropropionitrile;
Marononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, azelanitrile, sebaconitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, t-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-dimethylsuccino Nitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetra Methylglutaronitrile,
2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptan, 2,7- Dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-didianobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy) dipropio Nitrile, 3,3'-(ethylenedithio) dipropionitrile, 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, 3,3'-oxy Compounds having two nitrile groups such as dipropionitrile and 3,3'-thiodipropionitrile;
Cyclohexanetricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, pentanetricarbonitrile, 1,3,5-pentanetricarbonitrile, propantricarbonitrile, 1,2,3-propanetricarbonitrile, Examples thereof include compounds having three cyano groups such as heptanetricarbonitrile.

Of these, Valeronitrile, Decanenitrile, Lauronitrile, Crotononitrile, Succinonitrile, Glutaronitrile, Adiponitrile, Pimeronitrile, Suberonitrile, Azelanitrile, Sevaconitrile, Undecandinitrile, Dodecandinitrile, Fumaronitrile, 3,9-bis (2-Cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane is preferable from the viewpoint of improving the storage characteristics of the non-aqueous electrolyte solution. In addition, valeronitrile, decanenitrile, lauronitrile, crotononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [ 5,5] Nitrile compounds such as undecane are particularly preferable.

As the nitrile compound, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the nitrile compound in the entire non-aqueous electrolyte solution of the present invention is not limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the non-aqueous electrolyte solution. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1% by mass or less. When the above range is satisfied, the effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics of the non-aqueous electrolyte secondary battery are further improved.

1-2-4. Isocyanate compound The non-aqueous electrolyte solution according to the embodiment of the present invention preferably contains an isocyanate compound in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
The type of the isocyanate compound, which is a specific compound, is not particularly limited as long as it is a compound having an isocyanate group in the molecule.

Specific examples of the isocyanate compound include, for example.
Hydrocarbon-based monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, t-butyl isocyanate, pentyl isocyanate, hexyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, fluorophenyl isocyanate;
Monoisocyanate compounds with carbon-carbon unsaturated bonds such as vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propynyl 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-difluoro Hexaneous, toluenediisocyanate, xylenediocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) 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 (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (Methylisocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, 1,5-diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexa Hydrocarbon-based diisocyanate compounds such as methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate;
Isocyanatosulfone, (ortho-, meta-, para-) isocyanate compounds such as toluenesulfonylisocyanate, benzenesulfonylisocyanate, fluorosulfonylisocyanate, phenoxysulfonylisocyanate, pentafluorophenoxysulfonylisocyanate, methoxysulfonylisocyanate;
And so on.

Of these, monoisocyanate compounds having carbon-carbon unsaturated bonds such as vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, and propynyl 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-bis ( Isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6- Hydrocarbon-based diisocyanate compounds such as diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate;
Isocyanatosulfone, (ortho-, meta-, para-) toluenesulfonyl isocyanate, benzenesulfonylisocyanate, fluorosulfonylisocyanate, phenoxysulfonylisocyanate, pentafluorophenoxysulfonylisocyanate, methoxysulfonylisocyanate and other isocyanate compounds;
However, it is preferable from the viewpoint of improving the cycle characteristics and storage characteristics of the non-aqueous electrolyte secondary battery.

More preferably, allyl isocyanate, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, diisocyanatosulfone, (ortho-, meta-, para-) toluenesulfonyl isocyanate, and particularly preferably hexamethylene. Diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, (ortho-, meta-, para-) toluenesulfonyl isocyanate, most preferably hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane. is there.

Further, as the isocyanate compound, an isocyanate compound having a branched chain is preferable.
Further, the isocyanate compound used in the present invention may be a trimer compound derived from a compound having at least two isocyanate groups in the molecule, or an aliphatic polyisocyanate to which a polyhydric alcohol is added. Such aliphatic polyisocyanates include, for example, biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanates represented by the basic structures of the formulas (1-2-1) to (1-2-4). (In formulas (1-2-1) to (1-2-4), R and R'are independent hydrocarbon groups, respectively).

Among the isocyanate compounds used in the present invention, the compound having at least two isocyanate groups in the molecule also includes 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, and specific examples thereof include n-butanol, phenol, tributylamine, diethylethanolamine, and methylethylketoxim. ε-caprolactam and the like can be mentioned.

A metal catalyst such as dibutyltin dilaurate or 1,8-diazabicyclo [5.4.0] undecene is used for the purpose of promoting a reaction based on a compound having at least two isocyanate groups in the molecule and obtaining a higher effect. It is also preferable to use an amine-based catalyst such as −7 in combination.

As the isocyanate compounds described above, one type may be used alone, or two or more types may be used in combination in any combination and ratio.

The content of the isocyanate compound in the entire non-aqueous electrolyte solution is not limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less with respect to the non-aqueous electrolyte solution of the present invention. It is preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less.

When the above range is satisfied, the effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics of the non-aqueous electrolyte secondary battery are further improved.

1-2-5. A compound having an isocyanuric acid skeleton The non-aqueous electrolyte solution according to the embodiment of the present invention further contains a compound having an isocyanuric acid skeleton in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics. preferable.
Examples of the compound having an isocyanuric acid skeleton, which is one of the specific compounds, include a compound represented by the formula (U).

In the formula (U), R ^{7 to} R ⁹ are organic groups having 1 to 20 carbon atoms which may independently have a substituent. However, at least one of R ^{7 to} R ⁹ has a carbon-carbon unsaturated bond or a cyano group. Preferably, in the formula (U), R ^{7 to} R ⁹ are organic groups having 1 to 10 carbon atoms which may independently have a substituent. More preferably, in the formula (U), at least one of R ^{7 to} R ⁹ is an organic group having a carbon-carbon unsaturated bond.

Here, the organic group represents a functional group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom and a halogen atom.

Specific examples of the organic group having 1 to 20 carbon atoms which may have a substituent include an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkynyl group, an aryl group, a cyano group, an acrylic group and a methacryl group. Examples thereof include a vinylsulfonyl group and a vinylsulfo group.

Examples of the substituent here include a halogen atom and an alkylene group. Further, an unsaturated bond or the like may be contained in a part of the alkylene group. Among the halogen atoms, a fluorine atom is preferable.

Specific examples of the alkyl group which may have a substituent include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an s-butyl group, a t-butyl group and the like. Examples thereof include a chain-shaped or branched alkyl group, and a cyclic alkyl group such as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group.

Specific examples of the alkenyl group which may have a substituent include a vinyl group, an allyl group, a metalyl group, a 1-propenyl group and the like.

Specific examples of the alkynyl group which may have a substituent include an ethynyl group, a propargyl group, a 1-propynyl group and the like.

Specific examples of the aryl group which may have a substituent include a phenyl group, a tolyl group, a benzyl group, a phenethyl group and the like.

The substituent which may have a substituent described above is more preferably an alkyl group, an alkenyl group, an alkynyl group, an acrylic group, a methacryl group or a cyano group which may have a substituent.

Particularly preferred are an alkyl group, an alkenyl group, an acrylic group, a methacrylic group, and a cyano group which may have a substituent.

Most preferably, it is a methyl group, an ethyl group, a propyl group, an allyl group, or a metalyl group which may have a substituent. Particularly, an unsubstituted allyl group and a metalyl group are preferable. An allyl group is preferable from the viewpoint of film forming ability.

Specific examples of the compound represented by the formula (U) include compounds having the following structures.

Among the compounds represented by the formula (U), a compound having the following structure is preferable.

More preferably, it is a compound having the following structure.

Particularly preferred is a compound having the following structure.

Most preferably, it is a compound having the following structure.

Further, among these most preferable compounds, a compound having the following structure is preferable from the viewpoint of film forming ability.

The content of the compound having the isocyanuric acid skeleton described above (the compound represented by the formula (U)) in the entire non-aqueous electrolyte solution is not limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass, based on the entire non-aqueous electrolyte solution of the present invention. Hereinafter, it is preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less.

When the above range is satisfied, the effects such as output characteristics, load characteristics, cycle characteristics, high temperature storage characteristics, and battery swelling of the non-aqueous electrolyte secondary battery are further improved.

1-2-6. Fluorinated salt The non-aqueous electrolyte solution according to the embodiment of the present invention preferably contains a fluorinated salt in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
The fluorinated salt, which is a specific type of compound, is not particularly limited, but since it has a highly desorbable fluorine atom in its structure, for example, the compound represented by the formula (A) can be used. Difluorophosphates, fluorosulfonates, fluoroboron salts and fluoroimide salts are preferable because they can react suitably with anions (nucleophilic species) generated by the reduction reaction to form a complex film. Fluoroborone salt, fluorosulfonate, and difluorophosphate are more preferable, and fluoroboron salt and difluorophosphate are more preferable because the desorption of fluorine atoms is particularly high and the reaction with the nucleophile proceeds favorably. Especially preferable. Hereinafter, these various salts will be described.

(Difluorophosphate)
The counter cation of the difluorophosphate is not particularly limited, but lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ₁₃ R ₁₄ R ₁₅ R ₁₆ (in the formula, R _{13 to} R). ₁₆ each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms), and examples thereof include ammonium.

The organic group having 1 to 12 carbon atoms represented by R _{13 to} R ₁₆ of the ammonium is not particularly limited, but is substituted with, for example, an alkyl group which may be substituted with a halogen atom, a halogen atom or an alkyl group. Examples thereof include a cycloalkyl group which may be present, 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, it is preferable that R _{13 to} R ₁₆ are independently hydrogen atom, alkyl group, cycloalkyl group, or nitrogen atom-containing heterocyclic group.

As a specific example of difluorophosphate,
Examples thereof include lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate and the like, and lithium difluorophosphate is preferable.

As the difluorophosphate, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of difluorophosphate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired.

The content of difluorophosphate is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass in 100% by mass of the non-aqueous electrolyte solution. % Or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

(Fluorosulfate)
The counter cation of the fluorosulfonate is not particularly limited, but lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ₁₃ R ₁₄ R ₁₅ R ₁₆ (in the formula, R _{13 to} R). ₁₆ each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms), and examples thereof include ammonium.

The organic group having 1 to 12 carbon atoms represented by R _{13 to} R ₁₆ of the ammonium is not particularly limited, but is substituted with, for example, an alkyl group which may be substituted with a halogen atom, a halogen atom or an alkyl group. Examples thereof include a cycloalkyl group which may be present, 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, it is preferable that R _{13 to} R ₁₆ are independently hydrogen atom, alkyl group, cycloalkyl group, or nitrogen atom-containing heterocyclic group.

Specific examples of fluorosulfonates include
Examples thereof include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and lithium fluorosulfonate is preferable.

As the fluorosulfonate, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the fluorosulfonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired.

The content of the fluorosulfonate is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass in 100% by mass of the non-aqueous electrolyte solution. % Or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

(Fluoroboron salt)
The counter cation of the fluoroboron salt is not particularly limited, but lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ₁₃ R ₁₄ R ₁₅ R ₁₆ (in the formula, R _{13 to} R _16). Each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms), and examples thereof include ammonium.

The organic group having 1 to 12 carbon atoms represented by R _{13 to} R ₁₆ of the ammonium is not particularly limited, but is substituted with, for example, an alkyl group which may be substituted with a halogen atom, a halogen atom or an alkyl group. Examples thereof include a cycloalkyl group which may be present, 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, it is preferable that R _{13 to} R ₁₆ are independently hydrogen atom, alkyl group, cycloalkyl group, or nitrogen atom-containing heterocyclic group.

Specific examples of fluoroboron salts include
Examples thereof include LiBF ₄ , LiB (CiF _{2i + 1} ) _j (F) _4-j , and LiBF ₄ is preferable. In addition, i represents an integer of 1 to 10, and j represents an integer of 1 to 4.

As the fluoroboron salt, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the fluoroboron salt is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired.

The content of the fluoroboron salt is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 3% by mass in 100% by mass of the non-aqueous electrolyte solution. Hereinafter, it is preferably 1% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.5% by mass or less, and most preferably 0.3% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

(Fluoroimide salt)
The counter cation of the fluoroimide salt is not particularly limited, but lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ₁₃ R ₁₄ R ₁₅ R ₁₆ (in the formula, R _{13 to} R _16). Each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms.) Ammonium and the like represented by) can be mentioned as an example.

The organic group having 1 to 12 carbon atoms represented by R _{13 to} R ₁₆ of the ammonium is not particularly limited, but is substituted with, for example, an alkyl group which may be substituted with a halogen atom, a halogen atom or an alkyl group. Examples thereof include a cycloalkyl group which may be present, 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, it is preferable that R _{13 to} R ₁₆ are independently hydrogen atom, alkyl group, cycloalkyl group, or nitrogen atom-containing heterocyclic group.

Specific examples of fluoroimide salts include
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, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiN (FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ are preferable.

As the fluoroimide salt, one type may be used alone, or two or more types may be used in any combination and ratio. The content of the fluoroimide salt is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired.

The content of the fluoroimide salt is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass in 100% by mass of the non-aqueous electrolyte solution. Hereinafter, it is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

1-2-7. Cyclic Ether Compound The non-aqueous electrolyte solution according to the embodiment of the present invention preferably contains a cyclic ether compound in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
Examples of the cyclic ether compound which is one kind of the specific compound include a cyclic ether compound which is an aliphatic compound having an oxygen atom in the molecule and a cyclic ether compound which is an aromatic compound having an oxygen atom in the molecule. A cyclic ether compound, which is an aliphatic compound having an oxygen atom in the molecule, is preferable because the oxidation potential is appropriate and the amount of side reaction at room temperature can be reduced.

Specific examples of the cyclic ether compound include the following.
Ethylene oxide, propylene oxide, butylene oxide, styrene oxide, oxetane, 2-methyloxetane, 3-methyloxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 3-methyltetrahydrofuran, 3-ethyltetrahydrofuran, 2,2-dimethyl Tetrahydrofuran, 2,3-dimethyltetrahydrofuran, 2-vinyltetrahydrofuran, 3-vinyltetrahydrofuran, 2-ethynyltetrahydrofuran, 3-ethynyltetrahydrofuran, 2-phenyltetrahydrofuran, 3-phenyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropiran, 2- Ethyltetrahydropiran, 3-methyltetrahydropyran, 3-ethyltetrahydropiran, 4-methyltetrahydropyran, 4-ethyltetrahydropiran, 2,2-dimethyltetrahydropyran, 2,3-dimethyltetrahydropyran, 2,4-dimethyltetrahydro Piran, 3,3-dimethyltetrahydropirane, 3,4-dimethyltetrahydropirane, 4,4-dimethyltetrahydropirane, 2-vinyltetrahydropirane, 3-vinyltetrahydropirane, 4-vinyltetrahydrofuran, 2-ethynyltetrahydropirane, 3-Etinyltetrahydropirane, 4-ethynyltetrahydropirane, 2-phenyltetrahydropyran, 3-phenyltetrahydropirane, 4-phenyltetrahydropyran, hexamethylene oxide, 2-methylhexamethylene oxide, 3-methylhexamethylene oxide, 4- Ethylhexamethylene oxide, 2-vinylhexamethylene oxide, 3-ethynylhexamethylene oxide, 4-phenylhexamethylene oxide, heptamethylene oxide, 2-methylheptamethylene oxide, 3-methylheptamethylene oxide, 4-ethylheptamethylene oxide , Octamethylene oxide, nonamethylene oxide, decamethylene oxide, 1,3-dioxolane, 2-methoxy-1,3-dioxolane, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane , 4-Methyl-1,3-dioxolane, 2-ethoxy-1,3-dioxolane, 2-ethyl-1,3-dioxolane, 2,2-diethyl-1,3-dioxolane, 4-ethyl-1,3 − Dioxolane, 2,2,4-trimethyl-1,3-dio Xoran, 2,2,4-triethyl-1,3-dioxane, 1,3-dioxane, 4-methyl-1,3-dioxane, 2,4-dimethyl-1,3-dioxane, 2,2,4- Trimethyl-1,3-dioxane, 4-ethyl-1,3-dioxane, 2,4-dix-1,3-dioxane, 2,2,4-triethyl-1,3-dioxane, 4-phenyl-1, 3-dioxane, 3-methyl-1,3-dioxane, 5,5-dimethyl-1,3-dioxane, 2,5,5-trimethyl-1,3-dioxane, 4,6-dimethyl-1,3- Dioxane, 2,5-dimethyl-1,3-dioxane, 1,4-dioxane.

Among these, propylene oxide, butylene oxide, styrene oxide, oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 3-methyltetrahydrofuran, 3-ethyltetrahydrofuran, 2,2-dimethyltetrahydropyran, tetrahydropyran, 2-methyl Tetrahydropyran, 2-ethyltetrahydropyran, 3-methyltetrahydropyran, 3-ethyltetrahydropyran, 4-methyltetrahydropyran, 4-ethyltetrahydropyran, 2,2-dimethyltetrahydropyran, hexamethylene oxide, 1,3-dioxane , 4-Methyl-1,3-dioxane is preferred.
Propylene oxide, styrene oxide, oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropyran, 2-ethyltetrahydropyran, 2,2-dimethyltetrahydropyran, Hexamethylene oxide, 1,3-dioxane, 4-methyl-1,3-dioxane are more preferred.
Oxetane, tetrahydrofuran, tetrahydropyran, hexamethylene oxide, 1,3-dioxane, 4-methyl-1,3-dioxane are particularly preferred.
Tetrahydrofuran, tetrahydropyran, 1,3-dioxane are more preferred.
Tetrahydropyran is most preferred.
This is because the compound mentioned in the preferred example has a particularly large effect of suppressing gas generation.

As the cyclic ether compound, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the cyclic ether compound in the entire non-aqueous electrolyte solution of the present invention is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the non-aqueous electrolyte solution. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. By using the above content, it is possible to sufficiently exert the gas generation suppressing effect and suppress an unnecessary increase in resistance.

1-2-8. Oxalate salt The non-aqueous electrolyte solution according to the embodiment of the present invention preferably contains an oxalate salt in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
The counter cation of the oxalate salt, which is one of the specific compounds, is not particularly limited, but lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ₁₃ R ₁₄ R ₁₅ R ₁₆ (in the formula, Examples of R _{13 to} R ₁₆ include ammonium represented by a hydrogen atom or an organic group having 1 to 12 carbon atoms, respectively.

The organic group having 1 to 12 carbon atoms represented by R _{13 to} R ₁₆ of the ammonium is not particularly limited, but is substituted with, for example, an alkyl group which may be substituted with a halogen atom, a halogen atom or an alkyl group. Examples thereof include a cycloalkyl group which may be present, 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, it is preferable that R _{13 to} R ₁₆ are independently hydrogen atom, alkyl group, cycloalkyl group, or nitrogen atom-containing heterocyclic group.

As a specific example of the oxalate salt,
Lithium difluorooxalatobolate, lithium bis (oxalate) borate, lithium tetrafluorooxalattophosphate, lithium difluorobis (oxalate)
Phosphate, Lithium Tris (Oxalato) Phosphate, etc.
Lithium bis (oxalate) borate and lithium difluorobis (oxalate) phosphate are preferred.

As the oxalate salt, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the oxalate salt is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired.

The content of the oxalate salt is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the non-aqueous electrolyte solution. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1.5% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid the situation.

1-2-9. Cyclic sulfonic acid ester The non-aqueous electrolyte solution according to the embodiment of the present invention preferably further contains a cyclic sulfonic acid ester in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics.
The type of cyclic sulfonic acid ester, which is one of the specific compounds, is not particularly limited.

Specific examples of the cyclic sulfonic acid ester include, for example,
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-Propen-1,3-Sultone, 2-Propen-1,3-Sultone, 1-Fluoro-1-Propen -1,3-sultone, 2-fluoro-1-propen-1,3-sultone, 3-fluoro-1-propen-1,3-sultone, 1-fluoro-2-propen-1,3-sultone, 2 -Fluoro-2-propen-1,3-sultone, 3-fluoro-2-propen-1,3-sultone, 1-methyl-1-propen-1,3-sultone, 2-methyl-1-propen-1 , 3-Sultone, 3-Methyl-1-propen-1,3-Sultone, 1-Methyl-2-Propen-1,3-Sultone, 2-Methyl-2-Propen-1,3-Sultone, 3-Methyl -2-Propen-1,3-sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro -1,4-Butansultone, 1-Methyl-1,4-Butansultone, 2-Methyl-1,4-Butansultone, 3-Methyl-1,4-Butansultone, 4-Methyl-1,4-Butansultone, 1-Butene -1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1 , 4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1,4-sultone, 2-fluoro -2-buten-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1-fluoro-3-butene-1,4 -Sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1 -Butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone , 1-Methyl-2-butene-1,4 -Sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-
1,4-Sulton, 4-Methyl-2-butene-1,4-Sulton, 1-Methyl-3-butene-1,4-Sulton, 2-Methyl-3-butene-1,4-Sulton, 3- Methyl-3-butene-1,4-sulton, 4-methyl-3-butene-1,4-sulton, 1,5-pentanesulton, 1-fluoro-1,5-pentanesulton, 2-fluoro-1, 5-Pentane Sulton, 3-Fluoro-1,5-Pentane Sulton, 4-Fluoro-1,5-Pentane Sulton, 5-Fluoro-1,5-Pentane Sulton, 1-Methyl-1,5-Pentane Sulton, 2 -Methyl-1,5-pentanesulton, 3-methyl-1,5-pentanesulton, 4-methyl-1,5-pentanesulton, 5-methyl-1,5-pentanesulton, 1-pentene-1,5 -Pentane, 2-pentane-1,5-sulton, 3-pentane-1,5-sulton, 4-pentane-1,5-sulton, 1-fluoro-1-pentane-1,5-sulton, 2-fluoro -1-Pentane-1,5-sulton, 3-fluoro-1-pentane-1,5-sulton, 4-fluoro-1-pentane-1,5-sulton, 5-fluoro-1-pentane-1,5 -Sulton, 1-fluoro-2-pentane-1,5-sulton, 2-fluoro-2-pentane-1,5-sulton, 3-fluoro-2-pentane-1,5-sulton, 4-fluoro-2 -Pentane-1,5-sulton, 5-fluoro-2-pentane-1,5-sulton, 1-fluoro-3-pentane-1,5-sulton, 2-fluoro-3-pentane-1,5-sulton , 3-Fluoro-3-pentane-1,5-sultone, 4-fluoro-3-pentane-1,5-sulton, 5-fluoro-3-pentane-1,5-sulton, 1-fluoro-4-pentane -1,5-Sulton, 2-Fluoro-4-pentane-1,5-Sulton, 3-Fluoro-4-Pentane-1,5-Sulton, 4-Fluoro-4-Pentane-1,5-Sulton, 5 −Fluoro-4-pentane-1,5-sultone, 1-methyl-1-pentane-1,5-sulton, 2-methyl-1-pentane-1,5-sulton, 3-methyl-1-pentane-1 , 5-Sulton, 4-Methyl-1-pentane-1,5-Sulton, 5-Methyl-1-pentane-1,5-Sulton, 1-Methyl-2-pentane-1,5-Sulton, 2-Methyl -2-Pentane-1,5-Sulton, 3-Methyl-2-pentene-1,5-sultone, 4-methyl-2-pentene-1,5-sultone, 5-methyl-2-pentene-1,5-sultone, 1-methyl-3-pentene- 1,5-sultone, 2-methyl-3-penten-1,5-sultone, 3-methyl-3-penten-1,5-sultone, 4-methyl-3-penten-1,5-sultone, 5- Methyl-3-penten-1,5-sultone, 1-methyl-4-penten-1,5-sultone, 2-methyl-4-penten-1,5-sultone, 3-methyl-4-penten-1, Sultone compounds such as 5-sultone, 4-methyl-4-pentene-1,5-sultone, 5-methyl-4-pentene-1,5-sultone;
Sulfate compounds such as methylene sulphate, ethylene sulphate, propylene sulphate;
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-oxathiazole-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 4-methyl-1,2,4-oxathiazolidine-2,2- Dioxide, 3H-1,2,4-oxathiazole-2,2-dioxide, 5H-1,2,4-oxathiazole-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide , 5-Methyl-1,2,5-oxathiazolidine-2,2-dioxide, 3H-1,2,5-oxathiazole-2,2-dioxide, 5H-1,2,5-oxathiazole-2, 2-Dioxide, 1,2,3-oxathiadinane-2,2-dioxide, 3-methyl-1,2,3-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine- 2,2-Dioxide, 1,2,4-oxathiadinane-2,2-dioxide, 4-methyl-1,2,4-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,4- Oxathiazine-2,2-dioxide,
3,6-dihydro-1,2,4-oxathiadin-2,2-dioxide, 3,4-dihydro-1,2,4-oxathiadin-2,2-dioxide, 1,2,5-oxathiadinane-2, 2-Dioxide, 5-Methyl-1,2,5-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,6-dihydro-1, 2,5-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,5-oxathiazine-2,2-dioxide, 1,2,6-oxathiadinane-2,2-dioxide, 6-methyl- 1,2,6-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiadin-2,2-dioxide, 3,4-dihydro-1,2,6-oxathiadin-2, Nitrogen-containing compounds such as 2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide;
1,2,3-oxathiaphoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosrane-2,2-dioxide, 3-methyl-1,2,3-oxati Aphoslan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosrane-2,2,3-trioxide, 1,2,4-oxathiaphosrane-2,2-dioxide , 4-Methyl-1,2,4-oxathiaphosrane-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosrane-2,2,4-trioxide, 4-methoxy-1 , 2,4-oxathiaphoslan-2,2,4-trioxide, 1,2,5-oxathiaphosrane-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosrane- 2,2-Dioxide, 5-Methyl-1,2,5-oxathiaphosrane-2,2,5-trioxide, 5-methoxy-1,2,5-oxathiaphosrane-2,2,5- Trioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3- Oxatiaphosphinan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 1,2,4-oxathiaphosphinan-2,2 -Dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 4-methyl -1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 4-methoxy-1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 3-methoxy-1 , 2,4-oxathiaphosphinan-2,2,3-trioxide, 1,2,5-oxathiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan- 2,2-Dioxide, 5-Methyl-1,2,5-oxathiaphosphinan-2,2,3-trioxide, 5-methoxy-1,2,5-oxathiaphosphinan-2,2,3- Trioxide, 1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6- Oxatiaphosphinan-2,2,3-trioxide, 6-methoxy-1,2,6-oxatiaphosphinan-2,2 , 3-Trioxide and other phosphorus-containing compounds;
Can be mentioned.

Of these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propen-1, 3-sultone, 1-fluoro-1-propen-1,3-sultone, 2-fluoro-1-propen-1,3-sultone, 3-fluoro-1-propen-1,3-sultone, 1,4- Butan sultone, methylenemethanedisulfonate, and ethylenemethanedisulfonate are preferable from the viewpoint of improving the storage characteristics of the non-aqueous electrolyte solution.
1,3-Propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone More preferred.

One type of cyclic sulfonic acid ester may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the cyclic sulfonic acid ester in the entire non-aqueous electrolyte solution of the present invention is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the non-aqueous electrolyte solution. It is preferably 5% by mass or less, more preferably 3% by mass or less, particularly preferably 2% by mass or less, and most preferably 1% by mass or less. When the above range is satisfied, the effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics of the non-aqueous electrolyte secondary battery are further improved.

1-2-10. Chain carboxylic acid ester The non-aqueous electrolyte solution according to the embodiment of the present invention further contains a chain carboxylic acid ester as a solvent in addition to the compound represented by the formula (A) from the viewpoint of improving battery characteristics. preferable.
The chain carboxylic acid ester preferably has 3 to 7 carbon atoms. In particular,
Methyl acetate, ethyl acetate, -n-propyl acetate, isopropyl acetate, -n-butyl acetate, isobutyl acetate, -t-butyl acetate, methyl propionate, ethyl propionate, -n-propyl propionate, isopropyl propionate, propion Acid-n-butyl, isobutyl propionate, -t-butyl propionate, methyl butyrate, ethyl butyrate, -n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, -n-propyl isobutyrate, isopropyl butyrate And so on.

Among them, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, -n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate and the like have ionic conductivity due to a decrease in viscosity. It is preferable from the viewpoint of improvement of.

As the chain carboxylic acid ester, one type may be used alone, or two or more types may be used in combination in any combination and ratio.

The content of the chain carboxylic acid ester is usually 5% by volume or more, more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, it becomes easy to improve the electric conductivity of the non-aqueous electrolyte solution and improve the large current discharge characteristics of the non-aqueous electrolyte secondary battery. The content of the chain carboxylic acid ester is preferably 80% by volume or less, more preferably 70% by volume or less, particularly preferably 50% by volume or less, and most preferably 30% by volume or less in 100% by volume of the non-aqueous solvent. Is. By setting the upper limit in this way, an increase in the negative electrode resistance can be suppressed, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte secondary battery can be easily set in a good range.

1-3. Electrolyte <Alkali metal salt>
Alkali metal salts are used as the electrolyte, but lithium salts are usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used, and specific examples thereof include the following.

For _{example, LiPF 6, LiBF 4, LiClO} 4, LiAlF 4, LiSbF 6, inorganic lithium salts LiTaF 6, LiWF ₇ and the like;
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 Lithium carboxylic acid salts such as CO ₂ Li, CF ₃ CF ₂ CF ₂ 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 Lithium sulfonic acid salts such as CF ₂ SO ₃ 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 imide salts such as lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) ;
Lithiummethide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ;
Lithium oxalatoborate salts such as lithium difluorooxalate borate and lithium bis (oxalate) borate;
Lithium oxalat phosphate salts such as lithium tetrafluorooxalat phosphate, lithium difluorobis (oxalat) phosphate, lithium tris (oxalat) phosphate;
In addition, 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 (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ Fluorine-containing organic lithium salts such as; and the like.

Among them, LiPF ₆ , LiBF ₄ , 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 , Lithium bisoxalatoborate, Lithium difluorooxalatobolate, Lithium tetrafluorooxalat phosphate, Lithium difluorobisoxalatphosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _3, etc. are particularly preferable because they have the effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, and the like.

These lithium salts may be used alone or in combination of two or more. A preferable example of the combined use of two or more types is the combined use of LiPF ₆ and LiBF ₄ , LiPF ₆ and LiN (FSO ₂ ) ₂ , LiPF ₆ and FSO ₃ Li, etc., and has the effect of improving load characteristics and cycle characteristics. There is.
In this case, the concentration of LiBF4 or FSO 3 _Li for a non-aqueous electrolyte entire 100 wt% is not limited to the content, is optional unless significantly impairing the effects of the present invention, for non-aqueous electrolyte solution of the present invention It is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less.

Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of both has an effect of suppressing deterioration due to high temperature storage. Organolithium salts include 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 , Lithium bisoxalatoborate, Lithium difluorooxalatobolate, Lithium tetrafluorooxalatophosphate, Lithium difluorobisoxarat phosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _3, etc. are preferable. In this case, the ratio of the organolithium salt to 100% by mass of the entire non-aqueous electrolyte solution is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and preferably 30% by mass or less. , Particularly preferably 20% by mass or less.

The concentration of these lithium salts in the non-aqueous electrolyte solution is not particularly limited as long as the effect of the present invention is not impaired, but the electrical conductivity of the electrolyte solution is kept in a good range to ensure good battery performance. From this point of view, the total molar concentration of lithium in the non-aqueous electrolyte solution is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more, and also. It is preferably 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less.
When the total molar concentration of lithium is within the above range, the electric conductivity of the electrolytic solution becomes sufficient, and the decrease in electric conductivity due to the increase in viscosity and the resulting decrease in battery performance are prevented.

1-4. Non-aqueous solvent The non-aqueous solvent in the present invention is not particularly limited, and known organic solvents can be used. Examples thereof include cyclic carbonates having no fluorine atom, chain carbonates, cyclic carboxylic acid esters, ether compounds, sulfone compounds, and chain carboxylic acid esters. Hereinafter, these solvents will be described. For chain carboxylic acid ester, see 1-2-10. It is explained in.

<Cyclic carbonate without fluorine atom>
Examples of the cyclic carbonate having no fluorine atom include cyclic carbonate having an alkylene group having 2 to 4 carbon atoms.
Specific examples of the cyclic carbonate having no fluorine atom and having an alkylene group having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate and butylene carbonate. Of these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

As the cyclic carbonate having no fluorine atom, one type may be used alone, or two or more types may be used in combination in any combination and ratio.
The content 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, but the content when one of them is used alone is 100% by volume of a non-aqueous solvent. Medium, 5% by volume or more, more preferably 10% by volume or more. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte solution is avoided, and the large current discharge characteristics, stability with respect to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery are in a good range. It becomes easy to do. Further, it is 95% by volume or less, more preferably 90% by volume or less, still more preferably 85% by volume or less. By setting this range, the viscosity of the non-aqueous electrolyte solution can be set to an appropriate range, the decrease in ionic conductivity can be suppressed, and the load characteristics of the non-aqueous electrolyte battery can be easily set to a good range.

<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.
Specific examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate, methyl-n-propyl carbonate, n-butylmethyl carbonate, and isobutylmethyl. Examples thereof include carbonate, t-butylmethyl carbonate, ethyl-n-propyl carbonate, n-butylethyl carbonate, isobutylethyl carbonate, t-butylethyl carbonate and the like.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate and methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate are particularly preferable. is there.
In addition, chain carbonates having a fluorine atom (hereinafter, may be referred to as "fluorinated chain carbonate") can also be preferably used.

The number of fluorine atoms contained 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 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 its derivatives include fluoromethylmethyl carbonate, difluoromethylmethyl carbonate, trifluoromethylmethyl carbonate, bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis (trifluoromethyl) carbonate and the like. Be done.
Examples of fluorinated ethyl methyl carbonate and its derivatives 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 can be mentioned.

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, Examples thereof include 2,2-trifluoroethyl-2', 2'-difluoroethyl carbonate and bis (2,2,2-trifluoroethyl) carbonate.

As the chain carbonate, one type may be used alone, or two or more types may be used in combination in any combination and ratio.
The content of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, still more preferably 15% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution can be set in an appropriate range, the decrease in ionic conductivity can be suppressed, and the large current discharge characteristics of the non-aqueous electrolyte battery can be easily set in a good range. The chain carbonate is 90% by volume or less, more preferably 85% by volume or less, and particularly preferably 80% by volume or less in 100% by volume of the non-aqueous solvent. By setting the upper limit in this way, it is easy to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte solution and to easily set the large current discharge characteristic of the non-aqueous electrolyte battery in a good range.

<Cyclic carboxylic acid ester>
The cyclic carboxylic acid ester (lactone) preferably has 3 to 12 carbon atoms.
Specific examples thereof include gamma-butyrolactone, gamma valerolactone, gamma caprolactone, and epsilon caprolactone. Of these, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

As the cyclic carboxylic acid ester, one type may be used alone, or two or more types may be used in combination in any combination and ratio.
The content of the cyclic carboxylic acid ester is usually 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 solution can be improved, and the large current discharge characteristics of the non-aqueous electrolyte battery can be easily improved. The content 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 way, the viscosity of the non-aqueous electrolyte is set within an appropriate range, the decrease in electrical conductivity is avoided, the increase in negative electrode resistance is suppressed, and the large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to set the characteristics in a good range.

<Ether compounds>
As the ether-based compound, a chain ether having 3 to 10 carbon atoms in which a part of hydrogen may be substituted with fluorine and a cyclic ether having 3 to 6 carbon atoms 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) 2,2-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-propyl ether, ethyl (3-Fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetrafluoro-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-propyl ether, (2,2,2-trifluoroethyl) (3-fluoro-n-) (Propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2-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-tetra Fluoroethyl-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-propyl ether, (n-propyl) (3-fluoro) Ron-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-tetrafluoro-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-penta) Fluoro-n-propyl) ether, di (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane , Methoxy (2,2,2-trifluoroethoxy) 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) methane, di (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1) , 1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxy ethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2) , 2-Trifluoroethoxy) ether, methoxy (1,1,2,2-tetrafluoroethoxy) ether, diethoxyethane, ether Toxi (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- Examples thereof include propyl ether, ethylene glycol di-n-butyl ether and diethylene glycol dimethyl ether.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 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, and diethylene glycol dimethyl ether have high solvability to lithium ions and improve ionic dissociation. Dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable in terms of points, and particularly preferably because they have low viscosity and give high ionic conductivity.

As the ether compound, one kind may be used alone, or two or more kinds may be used in any combination and ratio.
The content 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 60% by volume or less, still more preferably 50% by volume or less.

Within this range, it is easy to secure the effect of improving the lithium ion dissociation degree of the chain ether and the ionic conductivity due to the decrease in viscosity. When the negative electrode active material is a carbonaceous material, the chain ether is combined with lithium ions. It is easy to avoid the situation where the capacity is reduced due to co-insertion.

<Sulfone compounds>
As the sulfone 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 1 or 2.

As a cyclic sulfone having 3 to 6 carbon atoms,
Trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones, which are monosulfone compounds;
Examples thereof include trimethylene disulfones, tetramethylene disulfones, hexamethylene disulfones, etc., which are disulfone compounds.

Among them, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable, from the viewpoint of dielectric constant and viscosity.
As the sulfolanes, sulfolanes and / or sulfolane derivatives (hereinafter, sulfolanes may also be referred to as "sulfolanes") are preferable. As the sulfolane derivative, one in which one or more hydrogen atoms bonded on the carbon atom 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-methyl sulfolane, 5-fluoro-3-methyl sulfolane, 5-fluoro-2-methyl sulfolane, 2-fluoromethyl sulfolane, 3-fluoromethyl sulfolane, 2-difluoromethyl sulfolane, 3-difluoro Methyl sulfolane, 2-trifluoromethyl sulfolane, 3-trifluoromethyl sulfolane, 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 because they have high ionic 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, t-butylmethylsulfone, t-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoro Ethylmethyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl Sulfone, Fluoromethyl-n-propyl sulfone, Difluoromethyl-n-propyl sulfone, Trifluoromethyl-n-propyl sulfone, Fluoromethyl isopropyl sulfone, Difluoromethyl isopropyl sulfone, Trifluoromethyl isopropyl sulfone, Trifluoroethyl-n-propyl Sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, Examples thereof include pentafluoroethyl-t-butyl sulfone.

Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-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-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, trifluoromethyl-t -Butyl sulfone or the like is preferable because it has high ionic conductivity and high input / output characteristics.

As the sulfone compound, one type may be used alone, or two or more types may be used in combination in any combination and ratio.
The content of the sulfone compound is usually 0.3% by volume or more, more preferably 1% by volume or more, still more preferably 5% by volume or more, and preferably 40% by volume in 100% by volume of the non-aqueous solvent. By volume or less, more preferably 35% by volume or less, still more preferably 30% by volume or less.
Within this range, it is easy to obtain the effect of improving durability such as cycle characteristics and storage characteristics, and the viscosity of the non-aqueous electrolyte solution can be set within an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte battery with a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

<When using a cyclic carbonate having a fluorine atom as a non-aqueous solvent>
Cyclic carbonate having a fluorine atom is used in a non-aqueous electrolyte solution in 1-2-2. As shown in, it can also be used as an auxiliary agent and can also be used as a non-aqueous solvent.
In the present invention, when a cyclic carbonate having a fluorine atom is used as a non-aqueous solvent, one of the above-exemplified non-aqueous solvents is referred to as a cyclic carbonate having a fluorine atom as a non-aqueous solvent other than the cyclic carbonate having a fluorine atom. It may be used in combination, or two or more kinds may be used in combination with a cyclic carbonate having a fluorine atom.

For example, one of the preferable combinations of the non-aqueous solvent is a combination mainly composed of a cyclic carbonate having a fluorine atom and a chain carbonate. Among them, the total of the cyclic carbonate having a fluorine atom and the chain carbonate in the non-aqueous solvent is preferably 60% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and the fluorine atom. The ratio of the cyclic carbonate having a fluorine atom to the total of the cyclic carbonate having and the chain carbonate is 3% by volume or more, preferably 5% by volume or more, more preferably 10% by volume or more, still more preferably 15% by volume or more. In addition, it is usually 60% by volume or less, preferably 50% by volume or less, more preferably 40% by volume or less, further preferably 35% by volume or less, particularly preferably 30% by volume or less, and most preferably 20% by volume or less.

When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and the high temperature storage characteristics (particularly, the residual capacity after high temperature storage and the high load discharge capacity) of the battery produced by using the combination may be improved.
For example, as a specific example of a preferable combination of a cyclic carbonate having a fluorine atom and a chain carbonate,
Monofluoroethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and diethyl carbonate, monofluoroethylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, monofluoro Examples thereof include ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

Among the combinations of the cyclic carbonate having a fluorine atom and the chain carbonate, those containing symmetric chain alkyl carbonates as the chain carbonate are more preferable, and in particular, monofluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and mono. Cycle characteristics include monofluoroethylene carbonates such as fluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, symmetrical chain carbonates and asymmetric chain carbonates. It is preferable because it has a good balance between high-current discharge characteristics. Among them, the symmetrical chain carbonates are preferably dimethyl carbonates, and the alkyl group of the chain carbonates is preferably 1 to 2 carbon atoms.

A combination of these cyclic carbonates having a fluorine atom and chain carbonates and a cyclic carbonate having no fluorine atom is also mentioned as a preferable combination. Among them, the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom in the non-aqueous solvent is preferably 10% by volume or more, more preferably 15% by volume or more, still more preferably 20% by volume or more. Yes, and preferably 50% by volume or less, more preferably 40% by volume or less, still more preferably 30% by volume or less, and fluorine with respect to the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom. The ratio of the cyclic carbonate having an atom is 1% by volume or more, preferably 3% by volume or more, more preferably 5% by volume or more, further preferably 10% by volume or more, particularly preferably 20% by volume or more, and preferably. It is 95% by volume or less, more preferably 85% by volume or less, still more preferably 75% by volume or less, and particularly preferably 60% by volume or less.

When a cyclic carbonate having no fluorine atom is contained in this concentration range, the electric conductivity of the electrolytic solution can be maintained while forming a stable protective film on the negative electrode.
Specific examples of a preferable combination of a cyclic carbonate having a fluorine atom, a cyclic carbonate having no fluorine atom, and a chain carbonate include
Monofluoroethylene carbonate, ethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate, ethylene carbonate and diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate and diethyl carbonate, monofluoro Ethylene carbonate, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate And propylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and propylene carbonate and diethyl carbonate, monofluoroethylene carbonate and propylene carbonate and ethylmethyl carbonate, monofluoroethylene carbonate and propylene carbonate and dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate and propylene. Carbonate, dimethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate, diethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate and ethylene carbonate Propropylene carbonate and dimethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl. Carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate and propylene carbonate Examples thereof include diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

Among the combinations of the cyclic carbonate having a fluorine atom, the cyclic carbonate having no fluorine atom, and the chain carbonate, those containing asymmetric chain alkyl carbonates as the chain carbonate are more preferable, and in particular,
Monofluoroethylene carbonate, ethylene carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate and dimethyl carbonate Ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, diethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate, diethyl carbonate and ethylmethyl Carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl. Those containing monofluoroethylene carbonate and asymmetric chain carbonates such as carbonate and ethylmethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate have cycle characteristics and large current discharge characteristics. It is preferable because it has a good balance. Among them, the asymmetric chain carbonates are preferably ethyl methyl carbonates, and the alkyl groups of the chain carbonates are preferably 1 to 2 carbon atoms.

When ethyl methyl carbonate is contained in the non-aqueous solvent, the ratio of ethyl methyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, still more preferably 25% by volume or more. It is particularly preferably contained in an amount of 30% by volume or more, preferably 95% by volume or less, more preferably 90% by volume or less, further preferably 85% by volume or less, and particularly preferably 80% by volume or less. , The load characteristics of the battery may be improved.
In the combination mainly composed of the cyclic carbonate having a fluorine atom and the chain carbonate, in addition to the cyclic carbonate having no fluorine atom, cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic ethers, and chains Other solvents such as ethers, sulfur-containing organic solvent, phosphorus-containing organic solvent, and fluorine-containing aromatic solvent may be mixed.

<When using a cyclic carbonate having a fluorine atom as an auxiliary agent, or when not using a cyclic carbonate having a fluorine atom>
In the present invention, when the cyclic carbonate having a fluorine atom is used as an auxiliary agent, one kind of the above-exemplified non-aqueous solvent may be used alone or two or more kinds as a non-aqueous solvent other than the cyclic carbonate having a fluorine atom. May be used in any combination and ratio. When the cyclic carbonate having a fluorine atom is not used, one of the above-exemplified non-aqueous solvents may be used alone, or two or more of them may be used in any combination and ratio. For example, as one of the preferable combinations of the non-aqueous solvent, a combination containing a cyclic carbonate having no fluorine atom and a chain carbonate as a main component, and a chain carbonate having no fluorine atom and a chain carboxylic acid ester as a main component. There are combinations.

Among them, the total of the cyclic carbonate having no fluorine atom and the chain carbonate in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and , Preferably 100% by volume or less, more preferably 95% by volume or less, still more preferably 90% by volume or less, and no fluorine atom-free cyclic relative to the total of the fluorine atom-free cyclic carbonate and the chain carbonate. The proportion of carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, and preferably 50% by volume or less, more preferably 35% by volume or less, still more preferably 30%. By volume or less, particularly preferably 25% by volume or less.
When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and the high temperature storage characteristics (particularly, the residual capacity after high temperature storage and the high load discharge capacity) of the battery produced by using the combination may be improved.

For example, as a specific example of a preferable combination of a cyclic carbonate having no fluorine atom and a chain carbonate,
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, propylene carbonate and ethyl methyl carbonate, propylene carbonate and ethyl methyl carbonate and diethyl carbonate, propylene carbonate, ethyl methyl carbonate and dimethyl carbonate and the like.

Among the combinations of cyclic carbonate and chain carbonate having no fluorine atom, those containing asymmetric chain alkyl carbonates as chain carbonate are more preferable, and in particular, ethylene carbonate and ethyl methyl carbonate and propylene carbonate and ethyl are particularly preferable. Methyl carbonate, ethylene carbonate and ethyl methyl carbonate and dimethyl carbonate, ethylene carbonate and ethyl methyl carbonate and diethyl carbonate, propylene carbonate and ethyl methyl carbonate and dimethyl carbonate, propylene carbonate and ethyl methyl carbonate and diethyl carbonate have cycle characteristics and high current. It is preferable because it has a good balance of discharge characteristics.

Among them, the asymmetric chain carbonates are preferably ethyl methyl carbonates, and the alkyl groups of the chain carbonates are preferably 1 to 2 carbon atoms.
When at least two kinds of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are contained in the non-aqueous solvent, for example, dimethyl carbonate and diethyl carbonate, or dimethyl carbonate and ethyl methyl carbonate, or ethyl methyl in the total non-aqueous solvent. The total ratio of carbonate and diethyl carbonate, or dimethyl carbonate and diethyl carbonate and ethyl methyl carbonate is preferably 10% by volume or more, more preferably 20% by volume or more, still more preferably 25% by volume or more, and particularly preferably 30% by volume. If it is contained in the above range, preferably 90% by volume or less, more preferably 80% by volume or less, further preferably 75% by volume or less, and particularly preferably 70% by volume or less, the load characteristics of the battery are improved. May improve.

For example, by containing dimethyl carbonate and ethyl methyl carbonate and increasing the content of dimethyl carbonate higher than the content of ethyl methyl carbonate, the electrical conductivity of the electrolytic solution can be maintained and the battery characteristics after high temperature storage are improved. May be preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate (dimethyl carbonate / ethyl methyl carbonate) in the total non-aqueous solvent is 1.1 or more in terms of improving the electrical conductivity of the electrolytic solution and improving the battery characteristics after storage. Is preferable, 1.5 or more is more preferable, and 2.5 or more is further preferable. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, further preferably 10 or less, and particularly preferably 8 or less in terms of improving battery characteristics.

In the above-mentioned combination mainly containing cyclic carbonate and chain carbonate having no fluorine atom, cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic ethers, chain ethers, sulfur-containing organic solvents, and phosphorus-containing compounds are used. Other solvents such as an organic solvent and an aromatic fluorine-containing solvent may be mixed.
In the present specification, the volume of the non-aqueous solvent is a measured value at 25 ° C., but for a solid at 25 ° C. such as ethylene carbonate, the measured value at the melting point is used.

1-5. Auxiliary agent In the non-aqueous electrolyte battery of the present invention, a compound represented by the general formula (A), a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, an isocyanate compound, and an isocyanuric acid skeleton. In addition to the compound having the above, the fluorinated salt, the cyclic ether compound, the oxalate salt, the cyclic sulfonic acid ester, and the chain carboxylic acid ester, an auxiliary agent may be appropriately used depending on the intended purpose. Examples of the auxiliary agent include the acid anhydride compounds shown below, fluorinated unsaturated cyclic carbonates, compounds having a triple bond, and other auxiliary agents.

1-5-1. Acid anhydride compounds The acid anhydride compounds include carboxylic acid anhydrides, sulfuric acid anhydrides, nitrate anhydrides, sulfonic acid anhydrides, phosphoric anhydrides, phosphite anhydrides, cyclic acid anhydrides, and chains. It is not limited to being an acid anhydride, and its structure is not particularly limited as long as it is an acid anhydride compound.

Specific examples of the acid anhydride compound include, for example,
Malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, glutaconic anhydride, itaconic anhydride, phthalic anhydride, phenylmaleic anhydride. 2,3-Diphenylmaleic anhydride, cyclohexane-1,2-dicarboxylic acid anhydride, 4-cyclohexene-1,2-dicarboxylic acid anhydride, 3,4,5,6-tetrahydrophthalic acid anhydride, 4 , 4'-Oxydiphthalic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, methyl-5-norbornen-2,3-dicarboxylic acid anhydride, phenylsuccinic anhydride, 2-phenylglutaric acid anhydride , Allyl succinic anhydride, 2-butene-11-yl succinic anhydride, (2-methyl-2-propenyl) succinic anhydride, tetrafluorosuccinic anhydride, diacetyl-tartrate anhydride, bicyclo [2.2. 2] Oct-7-ene-2,3,5,6-tetracarboxylic hydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid Examples thereof include anhydrides, methacrylic acid anhydrides, acrylic acid anhydrides, crotonic acid anhydrides, methanesulfonic anhydrides, trifluoromethanesulfonic anhydrides, nonafluorobutanesulfonic anhydrides, and acetic anhydride.

Of these
Succinic anhydride, maleic anhydride, citraconic anhydride, phenylmaleic anhydride, bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2) , 5-Dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-
Dicarboxylic acid anhydrides, allyl succinic anhydrides, acetic anhydride, methacrylic anhydrides, acrylic anhydrides, and methanesulfonic anhydrides are particularly preferred.
One type of acid anhydride compound may be used alone, or two or more types may be used in combination in any combination and ratio.

The content of the acid anhydride compound in the entire non-aqueous electrolyte solution of the present invention is not limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.001 with respect to the non-aqueous electrolyte solution of the present invention. Mass% or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2 It is contained in a concentration of mass% or less, particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less.
When the above range is satisfied, the effects such as output characteristics, load characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-5-2. Fluorinated unsaturated cyclic carbonate As the fluorinated cyclic carbonate, it is also preferable to use a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter, may be referred to as “fluorinated unsaturated cyclic carbonate”). The number of fluorine atoms contained in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. Among them, the number of fluorine atoms is usually 6 or less, preferably 4 or less, and 1 or 2 is most preferable.

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

As a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond,
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, 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, Examples thereof include 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, and 4,5-difluoro-4-phenylethylene carbonate.

Among them, as a preferable 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, 4-fluoro-4,5-diallylethylene carbonate, 4, 5-Difluoro-4,5-divinylethylene carbonate and 4,5-difluoro-4,5-diallylethylene carbonate are more preferably used because they form a stable interface protection film.

The molecular weight of the fluorinated 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 50 or more and 250 or less. Within this range, it is easy to secure the solubility of the fluorinated cyclic carbonate in the non-aqueous electrolyte solution, and the effect of the present invention is likely to be exhibited.
The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

As the fluorinated unsaturated cyclic carbonate, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired.
The content of the fluorinated unsaturated cyclic carbonate is usually 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more in 100% by mass of the non-aqueous electrolyte solution. It is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2% by mass or less.
Within this range, the non-aqueous electrolyte battery tends to exhibit a sufficient effect of improving the cycle characteristics, the high temperature storage characteristics are lowered, the amount of gas generated is increased, and the discharge capacity retention rate is lowered. Easy to avoid.

1-5-3. Compound having triple bond The type of the compound having a triple bond is not particularly limited as long as it is a compound having one or more triple bonds in the molecule.
Specific examples of the compound having a triple bond include the following compounds.
1-Pentin, 2-Pentin, 1-Hexyne, 2-Hexyne, 3-Hexyne, 1-Heptyne, 2-Heptyne, 3-Heptyne, 1-Octyne, 2-Octyne, 3-Octyne, 4-Octyne, 1- Nonin, 2-nonin, 3-nonin, 4-nonin, 1-dodecine, 2-dodecine, 3-dodecine, 4-dodecine, 5-dodecine, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2 -Propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentin, 5-phenyl-1-pentin, 1-phenyl-1-hexyne , 6-Phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, dicyclohexylacetylene and other hydrocarbon compounds;

2-Propinyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynylphenyl carbonate, 2-propynyl cyclohexyl carbonate, di-2-propynyl carbonate, 1-methyl-2-propynyl Methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate, 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate, 3-pentynyl methyl carbonate, 4-pentynyl methyl carbonate, etc. Monocarbonate;
2-Butin-1,4-diol dimethyldicarbonate, 2-butyne-1,4-diol diethyldicarbonate, 2-butyne-1,4-diol dipropyldicarbonate, 2-butyne-1,4-diol dibutyl Dicarbonates such as dicarbonate, 2-butyne-1,4-diol diphenyldicarbonate, 2-butyne-1,4-diol dicyclohexyldicarbonate;

2-Propinyl acetate, 2-Propinyl propionate, 2-Propinyl butyrate, 2-Propinyl benzoate, 2-Propinyl cyclohexylcarboxylic acid, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-Propionic acid Propinyl, butyric acid 1,1-dimethyl-2-propynyl, benzoate 1,1-dimethyl-2-propynyl, cyclohexylcarboxylic acid 1,1-dimethyl-2-propynyl, 2-butynyl acetate, 3-butynyl acetate, 2 acetate -Pentinyl, 3-pentynyl acetate, 4-pentynyl acetate, methyl acrylate, ethyl acrylate, propyl acrylate, vinyl acrylate, 2-propenyl acrylate, 2-butenyl acrylate, 3-butenyl acrylate, methyl methacrylate , Ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propenyl methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, methyl 2-propate, ethyl 2-propate, propyl 2-propate, 2 -Vinyl propate, 2-propenyl 2-propenyl, 2-butenyl 2-propate, 3-butenyl 2-propate, methyl 2-butanoate, ethyl 2-butanoate, propyl 2-butinate, 2-butin Vinyl acid acid, 2-propenyl 2-propenyl, 2-butenyl 2-butenyl, 3-butenyl 2-butenyl, methyl 3-butanoate, ethyl 3-butanoate, propyl 3-butanoate, vinyl 3-butane , 2-propenyl 3-butanoate, 2-butenyl 3-butenyl, 3-butenyl 3-butenyl, methyl 2-pentate, ethyl 2-pentate, propyl 2-pentate, vinyl 2-pentate, 2 -2-propenyl pentate, 2-butenyl 2-pentinate, 3-butenyl 2-pentanoate, methyl 3-pentate, ethyl 3-pentate, propyl 3-pentate, vinyl 3-pentinate, 3-pentyne 2-propenyl acid, 2-butenyl 3-pentate, 3-butenyl 3-pentate, methyl 4-pentate, ethyl 4-pentate, propyl 4-pentate, vinyl 4-pentate, 2-pentanoate 2 -Monocarboxylic acid esters such as propenyl, 2-butenyl 4-pentanoate, 3-butenyl 4-pentanoate;
2-Butin-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne Dicarboxylic acid esters such as -1,4-diol dicyclohexanecarboxylate;

Methyl oxalate 2-propinyl, ethyl oxalate 2-propynyl, propyl oxalate 2-propynyl, 2-propynyl oxalate vinyl, allyl oxalate 2-propinyl, di-2-propinyl oxalate, methyl 2-butynyl oxalate, 2-Butynyl ethyl oxalate, 2-butynylpropyl oxalate, 2-butynyl vinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynyl oxalate methyl, 3-butynyl oxalate ethyl , Oxalic acid diesters such as 3-butynylpropyl oxalate, 3-butynyl vinyl oxalate, allyl 3-butynyl oxalate, di-3-butynyl oxalate;

Methyl (2-propynyl) (vinyl) phosphine oxide, divinyl (2-propynyl) phosphine oxide, di (2-propynyl) (vinyl) phosphine oxide, di (2-propenyl) 2 (-propynyl) phosphine oxide, di (2) Phosphine oxides such as −propynyl) (2-propenyl) phosphine oxide, di (3-butenyl) (2-propynyl) phosphine oxide, and di (2-propynyl) (3-butenyl) phosphine oxide;

2-propynyl methyl (2-propenyl) phosphinic acid, 2-propynyl 2-butenyl (methyl) phosphinic acid, 2-propynyl di (2-propenyl) phosphinic acid, 2-propynyl di (3-butenyl) phosphinate, methyl ( 2-propenyl) phosphinic acid 1,1-dimethyl-2-propynyl, 2-butenyl (methyl) phosphinic acid 1,1-dimethyl-
2-Propinyl, di (2-propenyl) phosphinic acid 1,1-dimethyl-2-propynyl, and di (3-butenyl) phosphinic acid 1,1-dimethyl-2-propynyl, methyl (2-propynyl) phosphinic acid 2 -Propenyl, methyl (2-propynyl) phosphinic acid 3-butenyl, di (2-propynyl) phosphinic acid 2-propenyl, di (2-propynyl) phosphinic acid 3-butenyl, 2-propynyl (2-propenyl) phosphinic acid 2 -Phosphinic acid esters such as propenyl and 2-propynyl (2-propenyl) phosphinic acid 3-butenyl;

Methyl 2-propenyl phosphonate 2-propynyl, methyl 2-butenyl phosphonate (2-propynyl), 2-propenyl phosphonic acid (2-propynyl) (2-propenyl), 3-butenyl phosphonic acid (3-butenyl) (2-propynyl) ), 2-Propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-butenylphosphonic acid (1,1-dimethyl-2-propinyl) (methyl), 2-propenylphosphonic acid (1,1) -Dimethyl-2-propynyl) (2-propenyl), and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), methylphosphonic acid (2-propynyl) (2-propenyl), methylphosphonic acid (3-Butenyl) (2-propynyl), methylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl), methylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), ethyl Phosphonate (2-propynyl) (2-propenyl), ethylphosphonic acid (3-butenyl) (2-propynyl), ethylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl), and ethylphosphon Phosphonate esters such as acid (3-butenyl) (1,1-dimethyl-2-propynyl);

Phosphoric acid (methyl) (2-propenyl) (2-propynyl), phosphoric acid (ethyl) (2-propenyl) (2-propynyl), phosphoric acid (2-butenyl) (methyl) (2-propynyl), phosphoric acid (2-Butenyl) (Ethyl) (2-Propinyl), Phosphate (1,1-dimethyl-2-Propinyl) (Methyl) (2-Propenyl), Phosphate (1,1-dimethyl-2-Propinyl) ( Ethyl) (2-propenyl), phosphate (2-butenyl) (1,1-dimethyl-2-propynyl) (methyl), and phosphate (2-butenyl) (ethyl) (1,1-dimethyl-2- Phosphate esters such as propynyl);
Of these, a compound having an alkynyloxy group is preferable because it forms a negative electrode film more stably in the electrolytic solution.

further,
2-propynylmethyl carbonate, di-2-propynyl carbonate, 2-butyne-1,4-diol dimethyldicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, methyl 2-propynyl oxalate, Compounds such as di-2-propynyl oxalate are particularly preferable from the viewpoint of improving storage characteristics.

As the compound having a triple bond, one type may be used alone, or two or more types may be used in combination in any combination and ratio. The content of the compound having a triple bond with respect to the entire non-aqueous electrolyte solution of the present invention is not limited and is arbitrary as long as the effect of the present invention is not significantly impaired. Contained at a concentration of 01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less. Let me. When the above range is satisfied, the effects such as output characteristics, load characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-5-4. Other Auxiliary Agents As the other auxiliary agents, known auxiliary agents other than the above auxiliary agents can be used. Other auxiliaries include
Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate;
Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane;
Ethylene sulphite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methane sulfonate, ethyl methane sulfonate, busulfan, sulfolene, diphenyl sulfone, N, N-dimethylmethane sulfonamide, N, N-diethyl methanesulfonamide, vinyl Methyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl allyl sulfonate, propargyl allyl sulfonate, 1,2-bis (vinyl sulfonate) Sulfonate compounds such as ethane, lithium methylsulfate, lithium ethylsulfate, lithium propargylsulfate;

Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide;
Trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, dimethylphosphine Phosphorus-containing compounds such as methyl phosphate, ethyl diethylphosphine, trimethylphosphine oxide, triethylphosphine oxide;

Hydrocarbon compounds such as heptane, octane, nonane, decane, cycloheptane;
Fluoro-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride;
2-Propinyl 2- (diethoxyphosphoryl) acetate, 1-methyl-2-propynyl 2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propynyl 2- (diethoxyphosphoryl) acetate, pentafluorophenylmethane Sulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, methylpentafluorophenyl carbonate, 2-propynyl 2- (methanesulfonyloxy) propionic acid, 2- (methanesulfonyloxy) propionic acid 2 -Methyl, 2-ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl methanesulfonyloxyacetic acid, 2-methylmethanesulfonyloxyacetate, ethyl methanesulfonyloxyacetate, lithium ethyl methyloxycarbonylphosphonate, lithium ethyl ethyloxycarbonyl Phosphonate, Lithium Ethyl 2-Propinyloxycarbonylphosphonate, Lithium Ethyl 1-Methyl-2-Propinyloxycarbonylphosphonate, Lithium Ethyl 1,1-dimethyl-2-Propinyloxycarbonylphosphonate, Lithium Methyl Sulfate, Lithium Ethyl Sulfate, Lithium 2- Propinyl sulphate, lithium 1-methyl-2-propynyl sulphate, lithium 1,1-dimethyl-2-propynyl sulphate, lithium 2,2,2-trifluoroethyl sulphate, methyl trimethylsilyl sulphate, ethyl trimethylsilyl sulphate, 2-propynyl trimethylsilyl sulphate , Dilithium ethylene disulfate, 2-butin-1,4-diyl dimethanesulfonate, 2-butin-1,4-diyldiethanesulfonate, 2-butin-1,4-diyldiformate, 2-butin-1,4- Diyl diacetate, 2-butine-1,4-diyl dipropionate, 4-hexadiine-1,6-diyl dimethanesulfonate, 2-propynyl methanesulfonate, 1-methyl-2-propynyl methanesulfonate, 1,1-dimethyl- 2-Propinyl Methane Sulphonate, 2-Propinyl Ethane Sulfonate, 2-Propinyl Vinyl Sulfonate, Methyl 2-Propinyl Carbonate, Ethyl 2-Propinyl Carbonide, 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-oxathiolan-4-yl propionate, 5-methyl-1,2-oxathiolan-4-one 2,2-Dioxide, 5,5-dimethyl-1,2-oxathiolane-4-one 2,2-dioxide, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2-Isocyanatoethoxy) ethyl acrylate, 2- (2-isocyanatoethoxy) ethyl methacrylate, 2- (2-isocyanatoethoxy) ethyl crotonate, 2-allyl succinate anhydride, 2- (1-pentene-3-3) Il) Succinic anhydride, 2- (1-hexene-3-yl) succinic anhydride, 2- (1-hepten-3-yl) succinic anhydride, 2- (1-octene-3-yl) Succinic anhydride, 2- (1-nonen-3-yl) succinic anhydride, 2- (3-buten-2-yl) succinic anhydride, 2- (2-methylallyl) succinic anhydride, 2 -(3-Methyl-3-buten-2-yl) succinic anhydride and the like can be mentioned. These may be used alone or in combination of two or more. By adding these auxiliaries, the capacity retention characteristics and cycle characteristics after high temperature storage can be improved.

The content of the other auxiliary agent is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The other auxiliary agent is preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. Within this range, the effects of other auxiliaries are likely to be fully exhibited, gas generation during full charge and high temperature storage is suppressed, and battery characteristics such as electrochemical oxidation resistance and high load discharge characteristics are deteriorated. It is easy to avoid such a situation.

As described above, the above-mentioned non-aqueous electrolyte solution includes those existing inside the non-aqueous electrolyte battery described in the present invention.
Specifically, the components of the non-aqueous electrolyte solution such as lithium salt, solvent, and auxiliary agent are separately synthesized, and the non-aqueous electrolyte solution is prepared from the substantially isolated one, and the method described below is used. Non-aqueous electrolyte solution obtained by injecting liquid into a separately assembled battery When it is a non-aqueous electrolyte solution in a battery, or when the components of the non-aqueous electrolyte solution of the present invention are individually put in the battery, the inside of the battery When the same composition as the non-aqueous electrolyte solution of the present invention is obtained by mixing in, further, the compound constituting the non-aqueous electrolyte solution of the present invention is generated in the non-aqueous electrolyte battery to generate the non-aqueous electrolyte battery of the present invention. The case where the same composition as the aqueous electrolytic solution is obtained is also included.

2. 2. Battery configuration The non-aqueous electrolyte solution according to the embodiment of the present invention is suitable for use as an electrolytic solution for a secondary battery, for example, a lithium secondary battery among non-aqueous electrolyte batteries. Hereinafter, the non-aqueous electrolyte battery using the non-aqueous electrolyte battery of the present invention will be described.
The non-aqueous electrolyte battery according to an embodiment of the present invention can adopt a known structure, and typically includes a negative electrode and a positive electrode capable of occluding and releasing ions (for example, lithium ions), and the above-mentioned book. The non-aqueous electrolyte solution of the present invention is provided.

2-1. Negative electrode The negative electrode active material used for the negative electrode will be described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples include a carbonaceous material, a negative electrode active material containing metal particles that can be alloyed with Li and graphite particles, and the like. One of these may be used alone, or two or more thereof may be arbitrarily combined and used in combination.

<Negative electrode active material>
Examples of the negative electrode active material include a carbonaceous material, a negative electrode active material containing metal particles capable of alloying with Li and graphite particles, and the like.
Examples of the carbonaceous material include (1) natural graphite, (2) artificial graphite, (3) amorphous carbon, (4) carbon-coated graphite, (5) graphite-coated graphite, and (6) resin-coated graphite. ..

(1) Examples of natural graphite include scaly graphite, scaly graphite, soil graphite, and / or graphite particles obtained by subjecting these graphites to spheroidization, densification, or the like. Among these, spherical or ellipsoidal graphite that has been subjected to a spheroidizing treatment is particularly preferable from the viewpoint of particle packing property and charge / discharge rate characteristics.
As the device used for the spheroidizing process, for example, a device that repeatedly applies mechanical actions such as compression, friction, and shearing force including the interaction of particles mainly with impact force to the particles can be used.
Specifically, it has a rotor with a large number of blades installed inside the casing, and by rotating the rotor at high speed, mechanical actions such as impact compression, friction, and shearing force are applied to the carbon material introduced inside. , And a device that performs the spheroidizing process is preferable. Further, it is preferable that the carbon material has a mechanism for repeatedly giving a mechanical action by circulating the carbon material.

For example, in the case of sphericalizing using the above-mentioned device, the peripheral speed of the rotating rotor is preferably 30 to 100 m / sec, more preferably 40 to 100 m / sec, and 50 to 100 m / sec. It is more preferable to do so. Further, although the treatment can be carried out simply by passing a carbonaceous material, it is preferable to circulate or retain in the apparatus for 30 seconds or more, and to circulate or retain in the apparatus for 1 minute or more. More preferred.

(2) As artificial graphite, coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, polyvinyl chloride, etc. Organic compounds such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene silfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin are usually used in the range of 2500 ° C or higher and usually 3200 ° C or lower. Examples thereof include those produced by graphitization at temperature, crushing and / or classifying as necessary. At this time, a silicon-containing compound, a boron-containing compound, or the like can also be used as a graphitization catalyst. In addition, artificial graphite obtained by graphitizing mesocarbon microbeads separated in a pitch heat treatment process can be mentioned. Further, artificial graphite of granulated particles composed of primary particles can also be mentioned. For example, by mixing mesocarbon microbeads, graphitizable carbon material powder such as coke with graphitizable binder such as tar and pitch, and graphitizing catalyst, graphitizing and pulverizing if necessary. Examples thereof include graphite particles obtained by assembling or bonding a plurality of flat particles so that the orientation planes are non-parallel.

(3) As the amorphous carbon, an amorphous carbon which uses an easily graphitizable carbon precursor such as tar or pitch as a raw material and is heat-treated at least once in a temperature range (range of 400 to 2200 ° C.) where graphitization does not occur. Examples thereof include amorphous carbon particles that have been heat-treated using particles or a non-graphitizable carbon precursor such as a resin as a raw material.
(4) The carbon-coated graphite can be obtained by mixing natural graphite and / or artificial graphite with a carbon precursor which is an organic compound such as tar, pitch or resin, and heat-treating it once or more in the range of 400 to 2300 ° C. Examples thereof include a carbon graphite composite in which natural graphite and / or artificial graphite is used as nuclear graphite and amorphous carbon is coated on the nuclear graphite. The form of the composite may be a coating of the entire surface or a part thereof, or a composite of a plurality of primary particles using carbon derived from the carbon precursor as a binder. Carbon can also be deposited (CVD) on the graphite surface by reacting natural graphite and / or artificial graphite with hydrocarbon gases such as benzene, toluene, methane, propane, and aromatic volatiles at high temperatures. Graphite composites can also be obtained.

(5) As the graphite-coated graphite, natural graphite and / or artificial graphite is mixed with a carbon precursor of an easily graphitizable organic compound such as tar, pitch or resin, and once in the range of about 2400 to 3200 ° C. Examples thereof include graphite-coated graphite in which natural graphite and / or artificial graphite obtained by the above heat treatment is used as nuclear graphite, and graphite is coated on the entire or a part of the surface of the nuclear graphite.
(6) As the resin-coated graphite, natural graphite and / or artificial graphite obtained by mixing natural graphite and / or artificial graphite and a resin or the like and drying at a temperature of less than 400 ° C. is used as nuclear graphite, and the resin or the like is nuclear graphite. Examples thereof include resin-coated graphite coating the above.

Further, as the carbonaceous materials (1) to (6), one type may be used alone, or two or more types may be used in combination in any combination and ratio.
Examples of the organic compounds such as tar, pitch and resin used in (2) to (5) above include coal-based heavy oil, DC-based heavy oil, decomposition-based petroleum heavy oil, aromatic hydrocarbons, and N-ring compounds. , S-ring compounds, polyphenylenes, synthetic organic polymers, natural polymers, thermoplastic resins, thermosetting resins and the like, which are carbonizable organic compounds selected from the group. Further, the raw material organic compound may be used by being dissolved in a low molecular weight organic solvent in order to adjust the viscosity at the time of mixing.

Further, as the natural graphite and / or the artificial graphite which is a raw material of the nuclear graphite, the natural graphite which has been subjected to the spheroidizing treatment is preferable.
As an alloy-based material used as a negative electrode active material, if lithium can be occluded and released, lithium alone, a single metal and alloy forming a lithium alloy, or their oxides, carbides, nitrides, silicides, and sulfides. It may be either a substance or a compound such as a phosphate, and is not particularly limited. The elemental metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / semi-metal elements (that is, excluding carbon), and more preferably elemental metals of aluminum, silicon and tin. An alloy or compound containing these atoms. One of these may be used alone, or two or more thereof may be used in any combination and ratio.

<Physical properties of carbonaceous materials>
When a carbonaceous material is used as the negative electrode active material, it is desirable that it has the following physical properties.
(X-ray parameters)
The d value (interlayer distance) of the lattice planes (002 planes) determined by X-ray diffraction of carbonaceous materials is usually 0.335 nm or more, and usually 0.360 nm or less, 0.350 nm. The following is preferable, and 0.345 nm or less is more preferable. The crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

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

If the volume-based average particle size falls below the above range, the irreversible capacity may increase, resulting in a loss of initial battery capacity. On the other hand, if it exceeds the above range, a non-uniform coating surface is likely to occur when the electrode is produced by coating, which may not be desirable in the battery manufacturing process.
The volume-based average particle size is measured by dispersing carbon powder in a 0.2 mass% aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This is performed using a meter (for example, LA-700 manufactured by HORIBA, Ltd.). The median diameter obtained by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

(Raman R value)
The Raman R value of the carbonaceous material is a value measured by laser Raman spectroscopy, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1. It is 5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

If the Raman R value is less than the above range, the crystallinity of the particle surface becomes too high, and the number of sites where Li enters between layers may decrease due to charging and discharging. That is, the charge acceptability may decrease. Further, when the negative electrode is densified by pressing after being applied to the current collector, the crystals tend to be oriented in the direction parallel to the electrode plate, which may lead to deterioration of the load characteristics.
On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte solution is increased, and the efficiency may be lowered and the gas generation may be increased.

To measure the Raman spectrum, a Raman spectroscope (for example, a Raman spectroscope manufactured by Nippon Spectroscopy Co., Ltd.) is used to naturally drop the sample into the measurement cell and fill it, and then the surface of the sample in the cell is filled with an argon ion laser beam (or semiconductor). This is performed by rotating the cell in a plane perpendicular to the laser beam while irradiating the cell (laser beam). The resulting Raman spectrum, calculates the intensity _{I A} of the peak PA around 1580 cm ^-1, and measuring the intensity _{I B} of a peak PB around 1360 cm ^-1, the intensity ratio R of the _{(R =} I B / _{I A)} To do. The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention.

The Raman measurement conditions described above are as follows.
-Laser wavelength: Ar ion laser 514.5 nm (semiconductor laser 532 nm)
-Measurement range: 1100 cm ^{-1 to} 1730 cm ^-1
・ Raman R value: 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 more preferably less, ^{10 m} 2 · ^{g -1} or less are especially preferred.

If the value of the BET specific surface area is less than this range, the acceptability of lithium tends to deteriorate during charging when used as a negative electrode material, and lithium tends to precipitate on the electrode surface, which may reduce stability. On the other hand, if it exceeds this range, the reactivity with the non-aqueous electrolyte solution increases when used as the negative electrode material, gas generation tends to increase, and it may be difficult to obtain a preferable battery.
To measure the specific surface area by the BET method, a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken) is used to pre-dry the sample at 350 ° C. for 15 minutes under nitrogen flow, and then to atmospheric pressure. This is performed by the nitrogen adsorption BET 1-point method by the gas flow method using a nitrogen helium mixed gas accurately adjusted so that the relative pressure value of nitrogen is 0.3.

(Circularity)
When the circularity is measured as the degree of sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined by "circularity = (peripheral length of a corresponding circle having the same area as the projected particle shape) / (actual peripheral length of the projected particle shape)", and is theoretical when the circularity is 1. Become a true sphere.
The circularity of the particles in which the particle size of the carbonaceous material is in the range of 3 to 40 μm is preferably closer to 1, and preferably 0.1 or more, particularly 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. The high current density charge / discharge characteristics improve as the circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between the particles is increased, and the high current density charge / discharge characteristics for a short time may be lowered.

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

The method for improving the circularity is not particularly limited, but a spherical shape obtained by subjecting it to a spherical shape is preferable because the shape of the interparticle voids when the electrode body is formed is adjusted. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying shearing force and compressive force, and a mechanical / physical treatment method of granulating a plurality of fine particles by the adhesive force of the binder or the particles themselves. Can be 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 1 g · cm ^-3 or more. It is particularly preferable, 2 g · cm ^-3 or less is preferable, 1.8 g · cm ^-3 or less is further preferable, and 1.6 g · cm ^-3 or less is particularly preferable. If the tap density is lower than the above range, it may be difficult to increase the filling density when used as a negative electrode, and a high-capacity battery may not be obtained. On the other hand, if it exceeds the above range, the voids between the particles in the electrode become too small, it becomes difficult to secure the conductivity between the particles, and it may be difficult to obtain preferable battery characteristics.

To measure the tap density, pass through a sieve with a mesh size of 300 μm, drop the sample into a tapping cell of 20 cm ³ to fill the sample up to the upper end surface of the cell, and then use a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser), tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the volume 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. If the orientation ratio is less than the above range, the high-density charge / discharge characteristics may deteriorate. 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 pressure molding the sample. A molded product obtained by filling 0.47 g of a sample into a molding machine having a diameter of 17 mm and compressing it at 58.8 MN · m- ² was set using clay so as to be flush with the surface of the sample holder for measurement. Measure X-ray diffraction. From the peak intensities of (110) diffraction and (004) diffraction of the obtained carbon, the ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated.

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

(Aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more, usually 10 or less, preferably 8 or less, and even more preferably 5 or less. If the aspect ratio exceeds the above range, streaks or a uniform coated surface cannot be obtained at the time of electrode plate formation, and the high current density charge / discharge characteristics may deteriorate. The lower limit of the above range is the theoretical lower limit of the aspect ratio of the carbonaceous material.

The aspect ratio is measured by magnifying and observing the particles of the carbonaceous material with a scanning electron microscope. Arbitrary 50 graphite particles fixed to 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 them, and the carbonaceous material particles are observed three-dimensionally. The longest diameter A and the shortest diameter B orthogonal to the diameter A are measured, and the average value of A / B is obtained.

(Coverage)
The negative electrode active material may be coated with a carbonaceous material or a graphite material. Of these, coating with an amorphous carbonaceous material is preferable from the viewpoint of lithium ion acceptability, and the coverage is usually 0.5% or more and 30% or less, preferably 1% or more and 25% or less, more preferably. Is 2% or more and 20% or less. If this content is too large, the amorphous carbon portion of the negative electrode active material increases, and the lossless capacity when the battery is assembled tends to decrease. If the content is too small, the amorphous carbon moiety is not uniformly coated on the core graphite particles and strong granulation is not performed, and the particle size tends to be too small when pulverized after firing.
The final obtained content (coverage) of carbides derived from the organic compound of the negative electrode active material is the amount of the negative electrode active material, the amount of the organic compound, and the balance measured by the micro method based on JIS K 2270. It can be calculated by the following formula from the coal ratio.
Formula: Coverage of carbides derived from organic compounds (%) = (mass of organic compounds x residual coal ratio x 100) / {mass of negative electrode active material + (mass of organic compounds x residual carbon ratio)}

(Internal porosity)
The internal porosity of the negative electrode active material is usually 1% or more, preferably 3% or more, more preferably 5% or more, still more preferably 7% or more. Further, it is usually less than 50%, preferably 40% or less, more preferably 30% or less, still more preferably 20% or less. If the internal porosity is too small, the amount of liquid in the particles will be small and the charge / discharge characteristics will tend to deteriorate. If the internal porosity is too large, the interparticle gap will be small when the electrode is used, and the electrolytic solution will diffuse. Tends to be inadequate. Further, the voids are filled with substances such as amorphous carbon, a graphite material, and a resin that buffer the expansion and contraction of metal particles that can be alloyed with Li, or the voids are filled with the voids. May be.

<Negative electrode active material containing metal particles and graphite particles that can be alloyed with Li>.
In the present specification, the negative electrode active material containing Li and alloyable metal particles and graphite particles may be a mixture in which Li and alloyable metal particles and graphite particles are mixed in the state of mutually independent particles. Alternatively, it may be a composite in which metal particles that can be alloyed with Li are present on the surface or inside of the graphite particles. In the present specification, the composite (also referred to as composite particles) is not particularly limited as long as it is a particle containing metal particles and carbonaceous substances that can be alloyed with Li, but is preferably an alloy with Li. It is a particle in which convertible metal particles and carbonaceous substances are integrated by physical and / or chemical bonds. In a more preferable form, each solid component is dispersed in the particles to the extent that the metal particles and carbonaceous substances that can be alloyed with Li are present at least on the surface of the composite particle and inside the bulk. In the form in which carbonaceous materials are present in order to unite them by physical and / or chemical bonds. A more specific preferred form is a composite material composed of at least Li and alloyable metal particles and graphite particles, in which graphite particles, preferably natural graphite, have a curved structure and have a folded structure. In addition, it is a negative electrode active material characterized in that metal particles that can be alloyed with Li are present in the gaps in the folded structure having the curved surface. Further, the gap may be a void, and a substance such as amorphous carbon, a graphitic substance, or a resin that buffers the expansion and contraction of metal particles that can be alloyed with Li is present in the gap. May be good.

-Metal particles that can be alloyed with Li As a method for confirming that the metal particles are metal particles that can be alloyed with Li, identification of the metal particle phase by X-ray diffraction and observation of the particle structure by an electron microscope And elemental analysis, elemental analysis by fluorescent X-ray, and the like.
As the metal particles that can be alloyed with Li, any conventionally known metal particles can be used, but from the viewpoint of capacity and cycle life, the metal particles are, for example, Fe, Co, Sb, Bi, Pb, Ni, Ag. , Si, Sn, Al, Zr, Cr, P, S, V, Mn, As, Nb, Mo, Cu, Zn, Ge, In, Ti and W may be a metal or a compound thereof selected from the group. preferable. Further, an alloy composed of two or more kinds of metals may be used, and the metal particles may be alloy particles formed by two or more kinds of metal elements. Among these, a metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W or a metal compound thereof is preferable.
Examples of the metal compound include metal oxides, metal nitrides, metal carbides and the like. Further, an alloy composed of two or more kinds of metals may be used.

Among the metal particles that can be alloyed with Li, Si or Si metal compounds are preferable. The Si metal compound is preferably a Si metal oxide. Si or a Si metal compound is preferable in terms of increasing the capacity. In the present specification, Si or Si metal compounds are collectively referred to as Si compounds. The Si compound, _{specifically, SiO x, SiN x, SiC} x, SiZ x O y (Z = C, N) , and the like. The Si compound is preferably a Si metal oxide, and the Si metal oxide is SiO _x in the general formula. This general formula SiO _x is obtained by using silicon dioxide (SiO ₂ ) and metal Si (Si) as raw materials, and the value of x is usually 0 ≦ x <2. SiOx has a larger theoretical capacity than graphite, and amorphous Si or nano-sized Si crystals allow alkaline ions such as lithium ions to easily enter and exit, making it possible to obtain a high capacity.
The Si metal oxide is specifically represented as SiO _x , where x is 0 ≦ x <2, more preferably 0.2 or more and 1.8 or less, still more preferably 0. It is .4 or more and 1.6 or less, particularly preferably 0.6 or more and 1,4 or less, and X = 0 is particularly preferable. Within this range, it is possible to reduce the irreversible capacity due to the combination of Li and oxygen at the same time as having a high capacity.

-Average particle diameter (d50) of metal particles that can be alloyed with Li
The average particle size (d50) of the metal particles that can be alloyed with Li is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.3 μm, from the viewpoint of cycle life. It is usually 10 μm or less, preferably 9 μm or less, and more preferably 8 μm or less. When the average particle size (d50) is within the above range, volume expansion due to charge / discharge is reduced, and good cycle characteristics can be obtained while maintaining charge / discharge capacity.
The average particle size (d50) is determined by a laser diffraction / scattering particle size distribution measuring method or the like.

· Li and specific surface area by the BET method of BET specific surface area of Li can be alloyed metal particles capable of alloying metal particles normally 0.5~60m ² / g, is preferably 1~40m ² / g .. When the specific surface area of the metal particles that can be alloyed with Li by the BET method is within the above range, the charge / discharge efficiency and discharge capacity of the battery are high, lithium is taken in and out quickly in high-speed charge / discharge, and the rate characteristics are excellent, which is preferable.

-Oxygen content of metal particles that can be alloyed with Li The oxygen content of metal particles that can be alloyed with Li is not particularly limited, but is usually 0.01 to 8% by mass or 0.05 to 5% by mass. It is preferable to have. The oxygen distribution state in the particle may be present near the surface, inside the particle, or uniformly in the particle, but it is particularly preferable that the oxygen is present near the surface. When the amount of oxygen contained in the metal particles that can be alloyed with Li is within the above range, volume expansion due to charging and discharging is suppressed due to the strong bond between Si and O, which is preferable because the cycle characteristics are excellent.

-Content ratio of metal particles that can be alloyed with Li The content ratio of metal particles that can be alloyed with Li with respect to the total of metal particles that can be alloyed with Li and graphite particles is usually 1% by mass or more, preferably 2% by mass. That is all. Further, it is usually 99% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, still more preferably 25% by mass or less, still more preferably 20% by mass or less, particularly. It is preferably 15% by mass or less, and most preferably 10% by mass or less. Within this range, the coating film made of the compound represented by the formula (A) can preferably coat the metal particles that can be alloyed with Li, and can improve the adhesion to the graphite particles. preferable.

<Construction and manufacturing method of negative electrode>
The negative electrode can be manufactured by any known method. Specifically, as a method for manufacturing a negative electrode, for example, a method in which a binder, a conductive material, or the like is added to the above-mentioned negative electrode active material is directly rolled to form a sheet electrode, or a pellet electrode is compression-molded. However, usually, the above-mentioned negative electrode is subjected to a coating method, a vapor deposition method, a sputtering method, a plating method, or the like on a current collector for a negative electrode (hereinafter, may be referred to as a “negative electrode current collector”). A method of forming a thin film layer (negative electrode active material layer) containing an active material is used. In this case, a binder, a thickener, a conductive material, a solvent, etc. are added to the above-mentioned negative electrode active material to form a slurry, which is applied to the negative electrode current collector, dried, and then pressed to increase the density. , A negative electrode active material layer is formed on the negative electrode current collector.
Further, when an alloy-based material is used, a method of forming a thin film layer (negative electrode active material layer) containing the above-mentioned negative electrode active material by a method such as a vapor deposition method, a sputtering method, or a plating method is also used.

Examples of the material of the negative electrode current collector include steel, copper alloy, nickel, nickel alloy, stainless steel and the like. Of these, copper foil is preferable from the viewpoint of easy processing into a thin film and cost.
The thickness of the negative electrode current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less. If the thickness of the negative electrode current collector is too thick, the capacity of the entire battery may be reduced too much, and conversely, if it is too thin, handling may be difficult.

In addition, in order to improve the binding effect with the negative electrode active material layer formed on the surface, it is preferable that the surface of these negative electrode current collectors is roughened in advance. Surface roughening methods include blasting, rolling with a rough surface roll, polishing cloth with abrasive particles fixed, a grindstone, emeri buff, a wire brush equipped with a steel wire, etc. to polish the surface of the current collector. Specific polishing method, electrolytic polishing method, chemical polishing method and the like can be mentioned.

Further, in order to reduce the mass of the negative electrode current collector and improve the energy density per mass of the battery, a perforated type negative electrode current collector such as expanded metal or punching metal can also be used. The mass of this type of negative electrode current collector can be freely changed by changing the aperture ratio. Further, when the negative electrode active material layers are formed on both sides of this type of negative electrode current collector, the negative electrode active material layer is less likely to be peeled off due to the rivet effect through the holes. However, when the aperture ratio becomes too high, the contact area between the negative electrode active material layer and the negative electrode current collector becomes small, so that the adhesive strength may be rather low.

The slurry for forming the negative electrode active material layer is usually prepared by adding a binder, a thickener, or the like to the negative electrode material. The term "negative electrode material" as used herein refers to a material in which the negative electrode active material and the conductive material are combined.
The content of the negative electrode active material in the negative electrode material is usually 70% by mass or more, particularly preferably 75% by mass or more, and usually 97% by mass or less, particularly preferably 95% by mass or less. If the content of the negative electrode active material is too small, the capacity of the secondary battery using the obtained negative electrode tends to be insufficient, and if it is too large, the content of the conductive agent is relatively insufficient, resulting in electricity as the negative electrode. It tends to be difficult to secure conductivity. When two or more negative electrode active materials are used in combination, the total amount of the negative electrode active materials may satisfy the above range.

Examples of the conductive material used for the negative electrode include metal materials such as copper and nickel; carbon materials such as graphite and carbon black. One of these may be used alone, or two or more thereof may be used in any combination and ratio. In particular, it is preferable to use a carbon material as the conductive material because the carbon material also acts as an active material. The content of the conductive material in the negative electrode material is usually 3% by mass or more, particularly preferably 5% by mass or more, and usually 30% by mass or less, particularly preferably 25% by mass or less. If the content of the conductive material is too small, the conductivity tends to be insufficient, and if it is too large, the content of the negative electrode active material or the like is relatively insufficient, so that the battery capacity and strength tend to decrease. When two or more conductive materials are used in combination, the total amount of the conductive materials may satisfy the above range.

As the binder used for the negative electrode, any binder can be used as long as it is a material that is safe for the solvent and electrolytic solution used in the production of the electrode. For example, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer and the like can be mentioned. One of these may be used alone, or two or more thereof may be used in any combination and ratio. The content of the binder is usually 0.5 parts by mass or more, particularly 1 part by mass or more, and usually 10 parts by mass or less, particularly preferably 8 parts by mass or less, based on 100 parts by mass of the negative electrode material. If the content of the binder is too small, the strength of the obtained negative electrode tends to be insufficient, and if it is too large, the content of the negative electrode active material etc. is relatively insufficient, so that the battery capacity and conductivity tend to be insufficient. It becomes. When two or more binders are used in combination, the total amount of the binders may satisfy the above range.

Examples of the thickener used for the negative electrode include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and the like. One of these may be used alone, or two or more thereof may be used in any combination and ratio. The thickener may be used as needed, but when it is used, the content of the thickener in the negative electrode active material layer is usually in the range of 0.5% by mass or more and 5% by mass or less. Is preferable.

The slurry for forming the negative electrode active material layer is prepared by mixing the negative electrode active material with a conductive agent, a binder, and a thickener as necessary, and using an aqueous solvent or an organic solvent as a dispersion medium. To. Water is usually used as the aqueous solvent, but alcohols such as ethanol and organic solvents such as cyclic amides such as N-methylpyrrolidone are used in combination with water in a range of 30% by mass or less. You can also. The organic solvent is usually cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbides such as anisole, toluene and xylene. Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, and among them, cyclic amides such as N-methylpyrrolidone and linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. .. Any one of these may be used alone, or two or more thereof may be used in any combination and ratio.

The obtained slurry is applied onto the above-mentioned negative electrode current collector, dried, and then pressed to form a negative electrode active material layer. The method of application is not particularly limited, and a method known per se can be used. The drying method is not particularly limited, and known methods such as natural drying, heat drying, and vacuum drying can be used.

(Electrode density)
The electrode structure when the negative electrode active material is converted into an electrode is not particularly limited, but the density of the negative electrode active material existing on the current collector is preferably 1 g · cm ^-3 or more, and 1.2 g · cm ^-3 or more. Is more preferable, 1.3 g · cm ^-3 or more is particularly preferable, 2.2 g · cm ^-3 or less is preferable, 2.1 g · cm ^-3 or less is more preferable, and 2.0 g · cm ^-3 or less is more preferable. More preferably, 1.9 g · cm ^-3 or less is particularly preferable. If the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed, the initial irreversible capacity increases, and the non-aqueous system near the current collector / negative electrode active material interface High current density charge / discharge characteristics may deteriorate due to a decrease in the permeability of the electrolytic solution. Further, if it falls below the above range, the conductivity between the negative electrode active materials may decrease, the battery resistance may increase, and the capacity per unit volume may decrease.

2-2. Positive electrode <Positive electrode active material>
The positive electrode active material (lithium transition metal compound) used for the positive electrode will be described below.
<Lithium transition metal compound>
The lithium transition metal compound is a compound having a structure capable of desorbing and inserting Li ions, and examples thereof include sulfides, phosphate compounds, and lithium transition metal composite oxides. As the sulfide, a compound having a two-dimensional layered structure such as TiS ₂ or MoS ₂ or a strong substance represented by the general formula Me _x Mo ₆ S ₈ (Me is various transition metals including Pb, Ag, Cu). Examples thereof include a sulphide compound having a three-dimensional skeletal structure. Examples of the phosphate compound include those belonging to the olivine structure, which are generally represented by LiMePO ₄ (Me is at least one transition metal), and specifically, LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , Examples thereof include LiMnPO ₄ . Examples of the lithium transition metal composite oxide include those belonging to a spinel structure capable of three-dimensional diffusion and a layered structure capable of two-dimensional diffusion of lithium ions. Those having a spinel structure are generally represented as LiMe ₂ O ₄ (Me is at least one transition metal), and specifically LiMn ₂ O ₄ , LiCo MnO ₄ , LiNi _0.5 Mn _1.5 O. ₄ , LiCoVO _4, etc. can be mentioned. Those having a layered structure are generally represented as LiMeO ₂ (Me is at least one transition metal). Specifically, LiCoO ₂ , LiNiO ₂ , LiNi _1-x Co _x O ₂ , LiNi _1-x-y Co _x Mn _y O ₂ , LiNi _0.5 Mn _0.5 O ₂ , Li _1.2 Cr _{0. 4 Mn 0.4 O 2, Li 1.2} Cr 0.4 Ti 0.4 O 2, LiMnO 2 , and the like.

<composition>
Further, the lithium transition metal compound may be, for example, a lithium transition metal compound represented by the following composition formula (F) or (G).
1) When it is a lithium transition metal compound represented by the following composition formula (F)
Li _{1 + x} MO ₂ ... (F)
However, x is usually 0 or more and 0.5 or less. M is Ni and Mn, or Ni, M.
It is an element composed of n and Co, and the Mn / Ni molar ratio is usually 0.1 or more and 5 or less. The Ni / M molar ratio is usually 0 or more and 0.5 or less. The Co / M molar ratio is usually 0 or more and 0.5 or less. The rich portion of Li represented by x may be replaced with the transition metal site M.

In the above composition formula (F), the atomic ratio of the amount of oxygen is described as 2 for convenience, but there may be some non-stoichiometric ratio. Further, x in the above composition formula is a charged composition at the production stage of the lithium transition metal compound. Batteries on the market are usually aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be missing due to charging and discharging. In that case, in composition analysis, x when discharged to 3 V may be measured to be −0.65 or more and 1 or less.

Further, the lithium transition metal compound is excellent in battery characteristics when it is fired by high-temperature firing in an oxygen-containing gas atmosphere in order to enhance the crystallinity of the positive electrode active material.
Further, the lithium transition metal compound represented by the composition formula (F) may be a solid solution with Li ₂ MO ₃ called a 213 layer as shown in the composition formula (F').
αLi ₂ MO ₃・ (1-α) LiM'O ₂ ... (F')
In the composition formula (F'), α is a number satisfying 0 <α <1.

M is at least one metal element having an average oxidation number of 4+, and specifically, M is at least one metal element selected from the group consisting of Mn, Zr, Ti, Ru, Re and Pt. ..
M'is at least one metal element having an average oxidation number of 3+, preferably at least one metal element selected from the group consisting of V, Mn, Fe, Co and Ni, and more preferably. Is at least one metal element selected from the group consisting of Mn, Co and Ni.

2) When it is a lithium transition metal compound represented by the composition formula (G).
Li [Li _a M _b Mn _2-ba ] O _{4 + δ} ... (G)
However, M is an element composed of at least one of transition metals selected from Ni, Cr, Fe, Co, Cu, Zr, Al and Mg.
In the composition formula (G), the value of b is usually 0.4 or more and 0.6 or less.
When the value of b is in this range, the energy density per unit mass of the lithium transition metal compound is high.

Further, in the composition formula (G), the value of a is usually 0 or more and 0.3 or less. Further, a in the composition formula (G) is a charged composition at the production stage of the lithium transition metal compound. Batteries on the market are usually aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be missing due to charging and discharging. In that case, in composition analysis, a when discharged to 3 V may be measured to be −0.65 or more and 1 or less.

When the value of a is in this range, the energy density per unit mass of the lithium transition metal compound is not significantly impaired, and good load characteristics can be obtained.
Further, in the composition formula (G), the value of δ is usually in the range of ± 0.5.
When the value of δ is in this range, the stability as a crystal structure is high, and the cycle characteristics and high-temperature storage of a battery having an electrode manufactured by using this lithium transition metal compound are good.

Here, the chemical meaning of the lithium composition in the lithium nickel-manganese-based composite oxide, which is the composition of the lithium transition metal-based compound, will be described in more detail below.
To obtain the composition formulas a and b of the lithium transition metal compound, each transition metal and lithium are analyzed by an inductively coupled plasma emission spectrophotometer (ICP-AES) to obtain the ratio of Li / Ni / Mn. It is calculated by the thing.

From a structural point of view, it is considered that lithium related to a is replaced with the same transition metal site. Here, due to the lithium related to a, the average valence of M and manganese becomes larger than 3.5 valence due to the principle of charge neutrality.
Further, the lithium transition metal compound may be fluorine-substituted, and is described as LiMn ₂ O _4-x F _2x .

<blend>
Specific examples of the lithium transition metal-based compound having the above composition include, for example, Li _{1 + x} Ni _0.5 Mn _0.5 O ₂ , Li _{1 + x} Ni _0.85 Co _0.10 Al _0.05 O ₂ , Li _{1 + x} Ni. _0.33 Mn _0.33 Co _0.33 O ₂ , Li _{1 + x} Ni _0.45 Mn _0.45 Co _0.1 O ₂ , Li _{1 + x} Mn _1.8 Al _0.2 O ₄ , Li _{1 + xM} n _1.5 Examples include Ni _0.5 O _{4 and the} like. One of these lithium transition metal compounds may be used alone, or two or more thereof may be blended and used.

<Introduction of different elements>
Further, a foreign element may be introduced into the lithium transition metal compound. As different elements, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Ru, Rh, Pd, Ag, In, Sb, Te , Ba, Ta, Mo, W, Re, Os, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi , N, F, S, Cl, Br, I, As, Ge, P, Pb, Sb, Si and Sn are selected from any one or more. These different elements may be incorporated into the crystal structure of the lithium transition metal-based compound, or may not be incorporated into the crystal structure of the lithium transition metal-based compound, and may be a simple substance or a compound on the particle surface or grain boundaries thereof. It may be unevenly distributed.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery is formed by forming a positive electrode active material layer containing the above-mentioned lithium transition metal compound powder for a positive electrode material for a lithium secondary battery and a binder on a current collector.
For the positive electrode active material layer, is the positive electrode material, the binder, and the conductive material and the thickener used as needed mixed in a dry manner to form a sheet, which is then pressure-bonded to the positive electrode current collector? Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, which is applied to a positive electrode current collector and dried.

As the material of the positive electrode current collector, a metal material such as aluminum, stainless steel, nickel plating, titanium, or tantalum, or a carbon material such as carbon cloth or carbon paper is usually used. As for the shape, in the case of metal material, metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foam metal, etc., and in the case of carbon material, carbon plate, carbon thin film, carbon column. And so on. The thin film may be formed in a mesh shape as appropriate.

When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but it is usually preferably in the range of 1 μm or more and 100 mm or less. If it is thinner than the above range, the strength required for the current collector may be insufficient, while if it is thicker than the above range, the handleability may be impaired.
The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that is stable to the liquid medium used in the production of the electrode may be used. Resin-based polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber, isoprene rubber, butadiene rubber, ethylene -Rubber polymer such as propylene rubber, styrene-butadiene-styrene block copolymer and its hydrogen additive, EPDM (ethylene-propylene-diene ternary copolymer), styrene-ethylene-butadiene-ethylene copolymer, Thermoplastic elastomeric polymers such as styrene / isoprene styrene block copolymer and its hydrogenated additives, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin Soft resinous polymers such as polymers, fluoropolymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, and alkali metal ions (particularly lithium ions) Examples thereof include a polymer composition having ionic conductivity. In addition, as these substances, 1 type may be used alone, and 2 or more types may be used together in arbitrary combinations and ratios.

The proportion of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently retained and the mechanical strength of the positive electrode may be insufficient, which may deteriorate the 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.
The positive electrode active material layer usually contains a conductive material in order to increase conductivity. The type is not particularly limited, but specific examples include metallic materials such as copper and nickel, graphite such as natural graphite and artificial graphite (graphite), carbon black such as acetylene black, and amorphous carbon such as needle coke. Carbon materials and the like can be mentioned. In addition, as these substances, 1 type may be used alone, and 2 or more types may be used together in arbitrary combinations and ratios. The ratio of the conductive material in the positive electrode active material layer is usually 0.01% by mass or more and 50% by mass or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, and conversely, if it is too high, the battery capacity may decrease.

As the liquid medium for forming the slurry, a lithium transition metal compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as needed can be dissolved or dispersed. As long as it is a solvent, the type thereof is not particularly limited, and either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water, alcohol and the like, and examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N. , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. be able to. In particular, when an aqueous solvent is used, a dispersant is added together with the thickener, and a latex such as SBR is used to make a slurry. In addition, as these solvents, 1 type may be used alone, and 2 or more types may be used together in arbitrary combinations and ratios.

The content ratio of the lithium transition metal compound powder as the positive electrode material in the positive electrode active material layer is usually 10% by mass or more and 99.9% by mass or less. If the proportion of the lithium transition metal compound powder in the positive electrode active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.
The thickness of the positive electrode active material layer is usually about 10 to 200 μm.

The electrode density of the positive electrode after pressing is usually 2.2 g / cm ³ or more and 4.2 g / cm ³ or less.
The positive electrode active material layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the positive electrode active material.
Thus, a positive electrode for a lithium secondary battery can be prepared.

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 non-aqueous electrolyte solution according to the embodiment 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 separator can be used as long as the effects of the present invention are not significantly impaired. Among them, resins, glass fibers, inorganic substances and the like formed of a material stable to non-aqueous electrolytic solutions are used, and it is preferable to use a porous sheet or a non-woven fabric-like material having excellent liquid retention properties.

As the material of the resin and the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyether sulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferable, and polyolefins are more preferable. One of these materials may be used alone, or two or more of these materials may be used in any combination and ratio.

The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, further preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, further preferably 30 μm or less. If the separator is too thin than the above range, the insulating property and mechanical strength may decrease. Further, if it is too thick than the above range, not only the battery performance such as rate characteristics may be deteriorated, but also the energy density of the non-aqueous electrolyte secondary battery as a whole may be lowered.

Further, when a porous material such as a porous sheet or a non-woven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, still more preferably 45% or more. Further, it is usually 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too small than the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. On the other hand, if it is larger than the above range, the mechanical strength of the separator tends to decrease and the insulating property tends to decrease.

The average pore size 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. Further, if it falls below the above range, the film resistance may increase and the rate characteristics may deteriorate.
On the other hand, as the inorganic material, for example, 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 those having a particle shape or a fiber shape are used. Used.

As the form, a thin film such as a non-woven fabric, a woven cloth, or a microporous film is used. As the thin film shape, a thin film having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferably used. In addition to the above-mentioned 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 by using a resin binder can be used. For example, alumina particles having a 90% particle size of less than 1 μm are formed on both sides of the positive electrode by using a fluororesin as a binder to form a porous layer.

The characteristics of the separator in the non-electrolyte liquid secondary battery can be grasped by the galley value. The gullet value indicates the difficulty of passing air in the film thickness direction, and is represented by the number of seconds required for 100 ml of air to pass through the film. Therefore, the smaller the value, the easier it is to pass through, and the larger the value. It means that it is harder to pass through. That is, the smaller the value, the better the communication in the thickness direction of the film, and the larger the value, the poorer the communication in the thickness direction of the film. The communication property is the degree of connection of holes in the film thickness direction. If the galley value of the separator of the present invention is low, it can be used for various purposes. For example, when used as a separator for a non-aqueous lithium secondary battery, a low galley value means that lithium ions can be easily transferred, which is preferable because the battery performance is excellent. The galley value of the separator is arbitrary, but is preferably 10 to 1000 seconds / 100 ml, more preferably 15 to 800 seconds / 100 ml, and even more preferably 20 to 500 seconds / 100 ml. When the galley value is 1000 seconds / 100 ml or less, the electrical resistance is substantially low, which is preferable as a separator.

2-4. Battery design <Electrode group>
The electrode group may be either a laminated structure in which the positive electrode and the negative electrode are formed via the separator, or a structure in which the positive electrode and the negative electrode are spirally wound via the separator. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. ..

When the electrode group occupancy rate is less than the above range, the battery capacity becomes small. Further, if it exceeds the above range, the void space is small, and the internal pressure rises due to the expansion of the member due to the high temperature of the battery and the increase of the vapor pressure of the liquid component of the electrolyte, and the charge / discharge repetition performance as a battery. In some cases, various characteristics such as high temperature storage may be deteriorated, and a gas discharge valve that releases internal pressure to the outside may operate.

<Protective element>
As a protective element, PTC (Positive Temperature Coafficient) whose resistance increases when abnormal heat generation or excessive current flows, thermal fuse, thermistor, and current flowing in the circuit due to a sudden rise in battery internal pressure or internal temperature during abnormal heat generation are cut off. A valve (current cutoff valve) or the like can be used. It is preferable to select the protective element under conditions that do not operate under normal use with a high current, and it is more preferable to design the protective element so as not to cause abnormal heat generation or thermal runaway even without the protective element.

<Exterior body>
The non-aqueous electrolyte secondary battery according to the embodiment of the present invention is usually configured by accommodating the above-mentioned non-aqueous electrolyte, negative electrode, positive electrode, separator and the like in an exterior body (exterior case). There is no limitation on this exterior body, and a known one can be arbitrarily adopted as long as the effect of the present invention is not significantly impaired.

The material of the outer case is not particularly limited as long as it is a substance stable to the non-aqueous electrolyte solution used. Specifically, a nickel-plated steel plate, stainless steel, aluminum or aluminum alloy, magnesium alloy, metals such as nickel and titanium, or a laminated film (laminated film) of resin and aluminum foil is used. From the viewpoint of weight reduction, aluminum or aluminum alloy metal or laminated film is preferably used.

In the outer case using the above metals, the metals are welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed and sealed structure, or the above metals are used to caulk the structure via a resin gasket. There are things to do. Examples of the outer case using the above-mentioned laminated film include a case in which resin layers are heat-sealed to form a sealed and sealed structure. In order to improve the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when the resin layer is heat-sealed via the current collector terminal to form a closed structure, the metal and the resin are bonded to each other. Therefore, a resin having a polar group or a modification in which a polar group is introduced as an intervening resin is introduced. Resin is preferably used.

Further, the shape of the outer case is also arbitrary, and may be any of, for example, a cylindrical type, a square shape, a laminated type, a coin type, and a large size.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
The compounds used in Examples and Comparative Examples are shown below.

Compound 1

Compound 2

Compound 3

Compound 4

Compound 5

Compound 6

Compound 7

Compound 8

Compound 9

Compound 10

Compound 11

Compound 12

<Example 1-1, Comparative Examples 1-1-1-5>
[Preparation of non-aqueous electrolyte solution]
Under a dry argon atmosphere, 1.2 mol / mol of fully dried LiPF ₆ was added to a mixture (volume ratio 3: 4: 3) of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). L (as the concentration in the non-aqueous electrolyte solution) was dissolved, and 2.0% by mass of each of Compound 9 and Compound 10 was added to prepare an electrolytic solution (this is referred to as reference electrolytic solution 1). Additives were added to the whole reference electrolyte 1 at the ratio shown in Table 1 below to prepare an electrolyte. However, Comparative Example 1-1 is the reference electrolyte 1 itself. The "content (% by mass)" in the table is the concentration in 100% by mass of the non-aqueous electrolyte solution.

[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, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone. It was mixed with a disperser in a solvent to form a slurry. This was uniformly applied to both sides of an aluminum foil having a thickness of 21 μm, dried, and then pressed to obtain a positive electrode.

[Preparation of negative electrode]
Natural graphite powder as the negative electrode active material, thickener, aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose 1% by mass) as binder, and aqueous dispersion of styrene-butadiene rubber (styrene-butadiene rubber), respectively. The concentration was 50% by mass), and the mixture was mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a copper foil having a thickness of 12 μm, dried, and then pressed to obtain a negative electrode. In the negative electrode after drying, the mass ratio was such that natural graphite: sodium carboxymethyl cellulose: styrene butadiene rubber = 98: 1: 1.

[Manufacturing of non-aqueous electrolyte batteries (laminated type)]
The above positive electrode, negative electrode, and polyolefin separator were laminated in the order of negative electrode, separator, positive electrode, separator, and negative electrode. The battery element thus obtained was wrapped in an aluminum laminate film, injected with an electrolytic solution described later, and then vacuum-sealed to prepare a sheet-shaped non-aqueous electrolyte secondary battery.

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
In a constant temperature bath at 25 ° C., the non-aqueous electrolyte secondary battery of the laminated cell was charged with a constant current for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. CC-CV charging was performed at 0.2 C to 4.1 V. Then, aging was carried out under the conditions of 45 ° C. and 72 hours. Then, it was discharged to 3.0V at 0.2C to stabilize the non-aqueous electrolyte secondary battery. Further, CC-CV charging was performed at 0.2 C to 4.4 V, and then discharged to 3.0 V at 0.2 C for initial conditioning.

<Evaluation of non-aqueous electrolyte secondary battery>
[Charge storage test]
The cell after the initial capacity evaluation was again charged with CC-CV at 0.2 C to 4.4 V, and then stored at a high temperature at 85 ° C. for 6 hours. After the battery was sufficiently cooled, the battery was immersed in an ethanol bath to measure the volume, and the amount of generated gas was determined from the volume change before and after the storage test, and this was defined as the "charge storage gas amount".
Table 1 below shows the amount of charge storage gas standardized in Comparative Example 1-1.

As is clear from Table 1, when a non-aqueous electrolyte solution containing the compound represented by the formula (A) of the present invention is used (Example 1-1), the compound represented by the formula (A) is contained. The charge storage gas is suppressed more than in Comparative Example 1-1 which is not used. Further, according to Table 1, when a non-aqueous electrolyte solution to which an aromatic ester compound other than the compound represented by the formula (A) as in Comparative Examples 1-2 to 1-5 is added, the charge storage gas is increased or the charge storage gas is increased. , It has been shown that the effect of suppressing the charge storage gas is small. From this, it can be seen that the battery swelling during high temperature storage after charging is improved by using the non-aqueous electrolyte solution in which the compound represented by the formula (A) is added to the non-aqueous electrolyte solution.

<Examples 2-1 to 2-2, Comparative Examples 2-1 to 2-8>
[Preparation of non-aqueous electrolyte solution]
Under a dry argon atmosphere, 1.0 mol / L (as a concentration in a non-aqueous electrolyte solution) of sufficiently dried LiPF ₆ is dissolved in a mixture of EC and EMC (volume volume ratio 3: 7) to dissolve the electrolyte solution. (This is called the reference electrolyte 2). Additives were added to the whole reference electrolyte 2 at the ratio shown in Table 2 below to prepare an electrolyte.
[Evaluation of electrochemical oxidation resistance]
Platinum was prepared as the working electrode and metallic lithium was prepared as the counter electrode to the reference electrode, and the cells were immersed in the electrolytic solution to form a tripolar electrochemical cell. At room temperature, the potential of the working electrode is swept from the natural potential at a sweep rate of 5 mV / s to 6.0 V (Li / Li + reference) with respect to the potential of the reference electrode, and then swept to the natural potential at a sweep rate of 5 mV / s. The measurement was repeated. The amount of electricity from the natural potential in the first cycle and the second cycle to 5.5V (Li / Li + reference) is obtained, and this ratio (the amount of electricity in the second cycle / the amount of electricity in the first cycle) is set to "(2 cycles /). 1 cycle) Electricity ratio ”.
Table 2 below shows the (2 cycle / 1 cycle) electricity ratio.

As is clear from Table 2, when a non-aqueous electrolyte solution containing the compound represented by the formula (A) of the present invention is used (Examples 2-1 to 2-2), it is represented by the formula (A). The electricity content ratio is suppressed (2 cycles / 1 cycle) as compared with Comparative Examples 2-1 to 2-8 containing an aromatic carboxylic acid ester compound other than the compound. The smaller the value of the electricity amount ratio, the smaller the amount of electricity in the second cycle, indicating that the decomposition reaction of the electrolytic solution is suppressed. From this, by using a non-aqueous electrolyte solution to which the compound represented by the formula (A) is added, an insulating film is formed on the electrode, and the subsequent decomposition reaction of the non-aqueous electrolyte solution is effectively suppressed. You can see that it is doing.

<Example 3-1 and Comparative Examples 3-1 to 3-4>
[Preparation of non-aqueous electrolyte solution]
Under a dry argon atmosphere, 1.0 mol / L (as a concentration in a non-aqueous electrolyte solution) of sufficiently dried LiPF ₆ is dissolved in a mixture of EC and ethyl propionate (EP) (volume volume ratio 3: 7). To prepare an electrolytic solution (this is called a reference electrolytic solution 3). Additives were added to the reference electrolyte 2 and the reference electrolyte 3 at the ratios shown in Table 3 below to prepare electrolyte 2'(EMC solvent) and electrolyte 3 (EP solvent), respectively.
[Evaluation of electrochemical oxidation resistance]
Platinum was prepared as the working electrode and metallic lithium was prepared as the counter electrode to the reference electrode, and the cells were immersed in the electrolytic solution to form a tripolar electrochemical cell. At room temperature, the potential of the working electrode is swept from the natural potential at a sweep rate of 5 mV / s to 6.0 V (Li / Li + reference) with respect to the potential of the reference electrode, and then swept to the natural potential at a sweep rate of 5 mV / s. The measurement was performed. The amount of electricity in the first cycle of the reference electrolytes 2 and 3 was obtained, and this ratio (the amount of electricity in the electrolyte 3 (EP solvent) in the first cycle / the amount of electricity in the electrolyte 2'(EMC solvent) in the first cycle) was set to ". (EP solvent / EMC solvent) electrical quantity ratio ”.
Table 3 below shows the (EP solvent / EMC solvent) electrical ratio.

As is clear from Table 3, when a non-aqueous electrolyte solution containing the compound represented by the formula (A) of the present invention is used (Example 3-1), the (EP solvent / EMC solvent) electrical ratio is 1. It has been shown to be much smaller and suppressed. On the other hand, aromatic carboxylics other than the compounds represented by the formula (A) such as Comparative Example 3-1 and Comparative Examples 3-2-3-4 which do not contain the compound represented by the formula (A). When a non-aqueous electrolytic solution containing an acid ester compound was used (EP solvent / EMC solvent), the electrical quantity ratio increased more than 1, so that the EP solvent system decomposed the electrolytic solution more than the EMC solvent system. You can see that it is in progress. From this, it can be seen that the compound represented by the formula (A) effectively suppresses the decomposition reaction of the non-aqueous electrolyte solution in the EP solvent system.

According to the non-aqueous electrolyte solution of the present invention, there is a good balance of overall performance in terms of durability, capacity, resistance, output characteristics, etc., in particular, gas generation during full charge and high temperature storage is suppressed, and electricity is obtained. It is possible to provide a battery having excellent chemical oxidation resistance and a good balance between durability and electrochemical characteristics. Therefore, it can be suitably used in all fields such as electronic devices in which a non-aqueous electrolyte secondary battery is used.
The use of the non-aqueous electrolyte solution and the non-aqueous electrolyte solution secondary battery of the present invention is not particularly limited, and can be used for various known applications. Specific examples of its use are laptop computers, electronic book players, mobile phones, mobile faxes, mobile copies, mobile printers, portable audio players, small video cameras, LCD TVs, handy cleaners, transceivers, electronic notebooks, calculators, and memories. Cards, portable tape recorders, radios, backup power supplies, automobiles, bikes, motorized bicycles, bicycles, lighting equipment, toys, game equipment, watches, power tools, strobes, cameras, etc. can be mentioned.

Claims (7)

A nonaqueous electrolytic solution for a nonaqueous electrolyte secondary battery, non-aqueous non-aqueous electrolytic solution of with an alkali metal salt and a non-aqueous solvent, characterized by containing a compound represented by the formula (A) Electrolyte A non-aqueous electrolyte for secondary batteries .

(In the formula (A), R ^{1 to} R ³ represent hydrocarbon groups having 1 to 20 carbon atoms which may independently have a hydrogen atom or a substituent, and are among R ^{1 to} R ³ . , At least one represents an aryl group having 6 to 20 carbon atoms which may have a substituent. X represents a methyl group. A represents an integer of 1 to 5.) The non-aqueous electrolyte solution according to claim 1, wherein a is 1 or 2 in the formula (A). The non-aqueous electrolyte solution for a secondary battery . 2. The non-aqueous electrolyte solution according to claim 1 or 2, wherein the content of the compound represented by the formula (A) is 0.001% by mass or more and 10% by mass or less with respect to the total amount of the non-aqueous electrolyte solution. Non-aqueous electrolyte for next battery . Further from cyclic carbonates having a carbon-carbon unsaturated bond, cyclic carbonates having a fluorine atom, nitrile compounds, isocyanate compounds, compounds having an isocyanuric acid skeleton, fluorinated salts, cyclic ether compounds, oxalate salts and cyclic sulfonic acid esters. The non-aqueous electrolyte solution according to any one of claims 1 to 3, which contains at least one compound selected from the above group. Non-aqueous electrolyte solution for a secondary battery . The non -aqueous electrolyte solution according to any one of claims 1 to 4, wherein the non-aqueous solvent contains a chain carboxylic acid ester. The non-aqueous electrolyte solution for a secondary battery . In a non-aqueous electrolyte secondary battery including a positive electrode capable of storing and releasing lithium ions, a negative electrode capable of storing and releasing lithium ions, and a non-aqueous electrolyte solution, the non-aqueous electrolyte solution is claimed 1 to 5. The non-aqueous electrolyte secondary battery, which is the non-aqueous electrolyte for the non-aqueous electrolyte secondary battery according to any one of the above items. An electric vehicle equipped with the non-aqueous electrolyte secondary battery according to claim 6 as a power source.