JP7078482B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a non-aqueous electrolyte solution and a non-aqueous electrolyte secondary battery. Specifically, the present invention comprises a non-aqueous electrolyte solution containing a specific amount of a specific compound, and a non-aqueous electrolyte solution secondary battery using this non-aqueous electrolyte solution. Regarding.

Non-aqueous electrolyte secondary batteries such as lithium secondary batteries in a wide range of applications such as power supplies for mobile phones such as smartphones and so-called consumer small devices such as laptop computers, and in-vehicle power supplies for driving such as electric vehicles. Has been put into practical use.
Numerous studies have been made in the field of additives for non-aqueous electrolytes as a means for improving the battery characteristics of non-aqueous electrolyte secondary batteries.

For example, in Patent Document 1, the cycle capacity retention rate at 25 ° C. is improved by combining a non-aqueous electrolytic solution containing a titanium and niobium-containing composite oxide and a specific phosphorus compound typified by triphenylphosphine oxide in the negative electrode. The consideration to be made is disclosed.
Patent Document 2 discloses a study of improving the initial charge / discharge efficiency and the capacity retention rate during high-temperature storage by containing a small amount of a specific phosphorus compound in a non-aqueous electrolytic solution.

JP-A-2017-59393 Japanese Unexamined Patent Publication No. 2006-4746

In recent years, the increase in capacity of lithium secondary batteries, which are one of the non-aqueous electrolyte secondary batteries used for in-vehicle power supplies for electric vehicles and mobile phone power supplies such as smartphones, has been accelerated. In order to increase the capacity, there are few voids other than the constituent members in the battery case. On the other hand, it is known that when a lithium secondary battery is placed in a high temperature environment, the electrolytic solution is oxidatively decomposed at the positive electrode active material interface to generate gas typified by carbon dioxide and carbon monoxide. However, since the above-mentioned high-capacity lithium secondary battery has few voids in the case, there is a problem that the battery swells due to the generated gas. Therefore, it is important to suppress the generation of gas during high temperature storage.

However, according to the studies by the present inventors, it has been found that the electrolytic solution containing the specific phosphorus compound disclosed in Patent Documents 1 and 2 has a problem in gas generation during high temperature storage.

As a result of diligent studies to solve the above problems, the present inventor has found that the generation of gas in high temperature storage can be suitably suppressed by using a non-aqueous electrolytic solution containing a phosphorus compound having a specific structure. Reached.
That is, the present invention provides the specific embodiments shown in the following [1] to [7].
[1] Non-aqueous electrolyte solution A non-aqueous electrolyte solution for a secondary battery, wherein the non-aqueous electrolyte solution is a compound represented by the following general formula (A), (B) or (C) together with an electrolyte and a non-aqueous electrolyte solution. A non-aqueous electrolyte solution containing at least one of them.

In the formulas (A), (B) and (C), R ¹ to R ³ independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 10 carbon atoms, and X is 1 to 10 carbon atoms. Indicates an alkyl group of 10 or an aryl group having 6 to 18 carbon atoms.)
[2] The non-aqueous electrolyte solution further comprises at least one additive selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a fluorinated salt and an oxalate salt. The non-aqueous electrolyte solution according to [1], which is contained.
[3] The non-aqueous electrolyte solution according to [1] or [2], wherein X is an aryl group having 6 to 18 carbon atoms in the general formulas (A), (B) and (C).
[4] In the general formulas (A), (B) and (C), X is a phenyl group, [1] to [3].
] The non-aqueous electrolyte solution according to any one of.
[5] The content of the compound represented by the general formula (A), (B) or (C) is 0.001% by mass or more and 10% by mass or less with respect to the total amount of the non-aqueous electrolytic solution. The non-aqueous electrolyte solution according to any one of [1] to [4].
[6] The content of at least one compound selected from the group consisting of the cyclic carbonate having a carbon-carbon unsaturated bond, the cyclic carbonate having the fluorine atom, the fluorinated salt and the oxalate salt is said. 0.001% by mass with respect to the total amount of non-aqueous electrolyte solution
The non-aqueous electrolytic solution according to any one of [2] to [5], which is 10% by mass or less.
[7] A non-aqueous electrolyte secondary battery including a positive electrode and a negative electrode capable of storing and releasing metal ions and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is any one of [1] to [6]. The non-aqueous electrolyte secondary battery, which is the non-aqueous electrolyte according to 1.

According to the present invention, by using a non-aqueous electrolyte solution containing a specific phosphorus compound, it is possible to suitably suppress the generation of gas in high temperature storage and obtain a non-aqueous electrolyte secondary battery with less battery swelling. Will be.

Hereinafter, embodiments of the present invention will be described in detail. The following embodiments are examples (representative examples) of embodiments of the present invention, and the present invention is not limited thereto. Further, the present invention can be arbitrarily modified and implemented without departing from the gist thereof.

<1. Non-aqueous electrolyte>
<1-1. Compound represented by the general formula (A), (B) or (C)>
The non-aqueous electrolytic solution of the present invention is characterized by containing at least one compound among the compounds represented by the following general formulas (A), (B) or (C).

In the formulas (A), (B) and (C), R ¹ to R ³ independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 10 carbon atoms, and X is 1 to 10 carbon atoms. The alkyl group of the above or the aryl group having 6 to 18 carbon atoms is shown.
Specific examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a tert-butyl group, an n-pentyl group, a hexyl group and a heptyl. Examples include a group, an octyl group, a nonyl group, a decyl group and the like. Of these, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, hexyl group or tert-butyl group are more preferable, and methyl group, ethyl group, n-propyl group and n-
A butyl group, an n-pentyl group or a tert-butyl group, particularly preferably a methyl group, an ethyl group, a tert-butyl group or an n-butyl group, and most preferably a methyl group or an ethyl group.
This is because the concentration of the compound on the surface of the positive electrode active material is likely to proceed.

Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a tolyl group, a benzyl group, a phenethyl group and the like. Of these, a phenyl group or a tolyl group is preferable because the concentration of the compound in the positive electrode active material is likely to proceed.
In the general formulas (A) and (B), R ¹ to R ³ are preferably hydrogen atoms or methyl groups independently of each other. This is because the concentration of the compound in the positive electrode active material and the reaction activity are enhanced, and the surface of the active material can be suitably modified.

In the general formulas (A), (B) and (C), X is preferably an aryl group having 6 to 18 carbon atoms. Of these, a phenyl group and a tolyl group are more preferable. This is because the concentration of the compound in the positive electrode active material and the reaction activity are enhanced, and the surface of the active material can be suitably modified.
As the compound contained in the non-aqueous electrolytic solution of the present invention, the compound represented by the general formula (A) is preferable to the compound represented by the general formula (B).

As the compound used in the present invention, a compound represented by the general formula (A), (B) or (C) is used, and specific examples thereof include compounds having the following structures.

Of these, compounds having the following structures are preferable. This is because the excessive decomposition reaction on the active material is suppressed.

More preferably, a compound having the following structure can be mentioned. This is because the molecular size of the compound is suitable and the concentration rate on the surface of the active material of the compound is increased.

Particularly preferred are compounds having the following structures. This is because the reaction with the positive electrode active material proceeds favorably and the surface modification proceeds effectively.

Most preferably, a compound having the following structure can be mentioned. This is because the reaction with the positive electrode active material proceeds more preferably, and the surface modification proceeds most effectively.

The content of the compound represented by the general formula (A), (B) or (C) with respect to the total amount of the non-aqueous electrolyte solution of the present invention (if two or more thereof are contained, the total content thereof) is 0.001 mass. % Or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more. On the other hand, the upper limit is 4.5% by mass or less, preferably 4.0% by mass.
Below, it is more preferably 3.5% by mass or less, particularly preferably 3.0% by mass or less, and most preferably 2.0% by mass or less.

As the compound represented by the general formula (A), (B) or (C), a commercially available compound may be used, and in the case of production, the production method is not limited, and the compound is produced by a known method. Can be used.
When the content of the compound represented by the general formula (A), (B) or (C) with respect to the total amount of the non-aqueous electrolyte solution is within the above range, the modification reaction on the surface of the active material proceeds suitably and the storage at high temperature is performed. It is possible to create a battery that does not generate much gas and does not swell easily.

The mechanism by which the problem of the present invention can be solved by containing the compound of the general formula (A), (B) or (C) is presumed as follows.
When the lithium secondary battery is placed in a high temperature environment, carbon dioxide and carbon monoxide are generated by oxidative decomposition of carbonate compounds, which are constituents of the electrolytic solution, at the interface of the positive electrode active material. do. The high-capacity lithium secondary battery has a problem that the battery swells because the space for receiving the generated gas is small in the case. General formulas (A), (B)
) Or (C) has a highly polar moiety (P = O) in the structure, and therefore, by acting on the Lewis acid point of the transition metal oxide which is the positive electrode active material, it becomes a suitable active material. Can be adsorbed. Further, since the compound represented by the general formula (A), (B) or (C) has an unsaturated bond having high polymerization activity in the structure, after being adsorbed on the surface of the active material, it is subjected to oxidative decomposition of the electrolytic solution or the like. By reacting with the generated radical species, a complex film can be formed and the surface of the active material can be suitably modified. Since this film has insulating properties, it suppresses the decomposition of lithium salts, solvents, and other additives, which are constituents of the electrolytic solution, due to the oxidation reaction on the active material, and contributes to the suppression of gas generation during high-temperature storage. presume.

The method for incorporating the compound represented by the general formula (A), (B) or (C) into the non-aqueous electrolytic solution of the present invention is not particularly limited. In addition to the method of adding the above compound directly to the electrolytic solution,
Examples thereof include a method of generating the above compound in a battery or an electrolytic solution.
The content of the compound represented by the general formula (A), (B) or (C) in the present invention means the time when the non-aqueous electrolyte solution is manufactured, the time point when the non-aqueous electrolyte solution is injected into the battery, or the battery is shipped as a battery. It means the content at any time.

In the non-aqueous electrolyte solution of the present invention, in addition to the compound represented by the general formula (A), (B) or (C), a cyclic carbonate having a carbon-carbon unsaturated bond described later and a cyclic having a fluorine atom. By using at least one compound selected from the group consisting of carbonate, fluorinated salt and oxalate salt in combination, gas generation during high temperature storage is further suppressed, and a battery that does not easily swell can be obtained. Among these, a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom or a fluorinated salt is preferable, and a fluorinated salt is more preferable. Further, it is most preferable to contain three kinds of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom and a fluorinated salt.

<1-2. Cyclic carbonate compounds with carbon-carbon unsaturated bonds>
Cyclic carbonate with carbon-carbon unsaturated bond (hereinafter referred to as "unsaturated cyclic carbonate")
As long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond, there is no particular limitation, and any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

The unsaturated cyclic carbonates include vinylene carbonates; ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds or carbon-carbon triple bonds; phenyl carbonates; vinyl carbonates; allyl carbonates; Examples thereof include catechol carbonates.
Examples of vinylene carbonates include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, and 4,5-.
Diphenyl vinylene 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- Examples thereof include phenylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate and the like.

Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinylethylene carbonate, and 4-methyl-5. Vinyl ethylene carbonate, 4-allyl-
5-Vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-dietinyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-
5-Ethynyl Ethylene Carbonate, 4-allyl-5-Etinylethylene 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-
Examples thereof include 5-allylethylene carbonate.

Among them, preferred unsaturated cyclic carbonates include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, vinylvinylene carbonate, 4,5-vinylvinylene carbonate, allylvinylene carbonate, 4,5-diallylvinylene carbonate and vinyl. Ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinyl Examples thereof include ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate or 4-vinyl-5-ethynyl ethylene carbonate.

Further, vinylene carbonate, vinylethylene carbonate or ethynylethylene carbonate is particularly preferable because it forms a more stable interface protective film.
The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The molecular weight is preferably 80 or more and 250 or less. Within this range, it is easy to secure the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolyte solution, and the effect of the present invention is likely to be sufficiently exhibited. The molecular weight of the unsaturated cyclic carbonate is more preferably 85.
The above is more, and more preferably 150 or less. The method for producing the unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production.

As the 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 amount of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but it is usually 0 with respect to the total amount of the non-aqueous electrolyte solution.
.. 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, particularly preferably 1% by mass or more, and usually 1
It is 0% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Within this range, non-aqueous electrolyte batteries tend to exhibit a sufficient effect of improving cycle characteristics, and the high-temperature storage characteristics deteriorate, the amount of gas generated increases, and the discharge capacity retention rate decreases. Easy to avoid.

<1-3. Cyclic carbonate with fluorine atom>
Examples of the cyclic carbonate compound having a fluorine atom include a fluorinated product of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms and a derivative thereof, and examples thereof include a fluorinated product of ethylene carbonate and a derivative 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). Of these, ethylene carbonate having 1 to 8 fluorine atoms and its derivatives are preferable.

As the cyclic carbonate having a fluorine atom, monofluoroethylene carbonate,
4,4-Difluoroethylene carbonate, 4,5-difluoroethylene carbonate,
4-Fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -Ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4
-(Fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene Examples include carbonate.

Among them, 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 protective film. Is more preferable.
As the cyclic carbonate compound 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.

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 amount 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. 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, particularly preferably 1% by mass or more, and usually 10% by mass or less, preferably 7% by mass.
Below, it is 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.

<1-4. Fluorinated salt>
The fluorinated salt is not particularly limited, but since it has a highly desorbable fluorine atom in its structure, for example, an anion generated by a reduction reaction of a compound represented by the general formula (A) ( A salt having a difluorophosphate, a fluorosulfonate or a bisfluorosulfonylimide structure is preferable because it can react suitably with the nucleophilic species) to form a complex film. Difluorophosphate or fluorosulfonate is more preferable because the desorption of fluorine atoms is particularly high and the reaction with the nucleophilic species proceeds favorably. 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,
Examples thereof include ammonium represented by NR ¹³ R ¹⁴ R ¹⁵ R ¹⁶ (in the formula, R ¹³ to R ¹⁶ each independently represent a hydrogen atom or an organic group having 1 to 12 carbon atoms). Can be mentioned.

The organic group having 1 to 12 carbon atoms represented by R ¹³ to R ¹⁶ in the above ammonium is not particularly limited, and is, for example, substituted with 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 substituted, 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 the difluorophosphate include lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate and the like, with lithium difluorophosphate being preferred.
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 blending amount of difluorophosphate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but the blending amount of difluorophosphate is usually the total amount of the non-aqueous electrolyte solution. 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, preferably 5% by mass or less, more preferably 3% by mass or less, further. It is preferably 2% by mass or less, and most preferably 1% by mass or less. Within this range, swelling of the non-aqueous electrolyte battery due to charging / discharging can be suitably suppressed.

<< Fluorosulfate >>
The counter cation of the fluorosulfonate is not particularly limited, but is the same as in the case of the difluorophosphate.
Specific examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and the like, 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 blending amount of the fluorosulfonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but the blending amount of the fluorosulfonate is usually the total amount of the non-aqueous electrolyte solution. 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, preferably 5% by mass or less,
More preferably 3% by mass or less, further preferably 2% by mass or less, and most preferably 1% by mass.
It is as follows. Within this range, swelling of the non-aqueous electrolyte battery due to charging / discharging can be suitably suppressed.

<Salt having a bisfluorosulfonylimide structure>
The counter cation of the salt having a bisfluorosulfonylimide structure is not particularly limited, but is the same as in the case of the difluorophosphate.
Examples of the salt having a bisfluorosulfonylimide structure include lithium bisfluorosulfonylimide, sodium bisfluorosulfonylimide, potassium bisfluorosulfonylimide and the like, and among them, lithium bisfluorosulfonylimide is preferable.

The blending amount of the salt having a bisfluorosulfonylimide structure is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1 with respect to the total amount of the non-aqueous electrolyte solution.
It is contained in a concentration of mass% or more, usually 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. Within this range, swelling of the non-aqueous electrolyte battery due to charging / discharging can be suitably suppressed.

<1-5. Oxalate salt>
The counter cation of the oxalate salt is not particularly limited, but is the same as in the case of the difluorophosphate.
Specific examples of the oxalate salt include lithium difluorooxalattobolate, lithium bis (oxalat) borate, lithium tetrafluorooxalattophosphate, lithium difluorobis (oxalat) phosphate, lithium tris (oxalat) phosphate, and the like. Of these, lithium bis (oxalate) borate or lithium difluorobis (oxalate) phosphate is preferable.

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 blending amount of the oxalate salt is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but the blending amount of the oxalate salt is usually 0.001 mass by mass with respect to the total amount of the non-aqueous electrolyte solution. % Or more, preferably 0.01% by mass or more, more preferably 0.1
It is usually 10% by mass 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 1.5% 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.

<1-6. Electrolyte>
Like a general non-aqueous electrolyte solution, the non-aqueous electrolyte solution of the present invention usually contains an arbitrary electrolyte other than the above-mentioned materials, but a lithium salt is preferably used as the electrolyte.

<< Lithium salt >>
The lithium salt is not particularly limited as long as it is known to be used for an electrolytic solution, and any lithium salt can be used, and specific examples thereof include the following.
For example, LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , L.
Inorganic lithium salts such as iWF ₇ ; Lithium fluorophosphates such as LiPF ₆ ; LiWOF
Lithium salts of tungstic acid such as 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
Lithium carboxylic acid salts such as CO ₂ Li, CF ₃ CF ₂ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li; Lithium sulfonic acid salts such as CH ₃ SO ₃ Li; LiN (FC)
O ₂ ) 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-Perfluoropropanedi Lithium imide salts such as sulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ S)
O ₂ ) Lithium methide salts such as ₃ ; lithium difluorooxalate borate, lithium bis (oxalat) borate, lithium tetrafluorooxalattophosphate, lithium difluorobis (oxalat) phosphate, lithium tris (oxalat) phosphate and the like. Borate salts; 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
Fluorine-containing organolithium salts such as ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ and the like;

Inorganic lithium salts, fluorophosphate lithium salts, sulfonic acid lithium salts, lithium imide from the viewpoint of further enhancing the effect of improving charge / discharge rate charge / discharge characteristics and impedance characteristics in addition to the gas suppression effect obtained by the present invention during high-temperature storage. Those selected from salts and lithium oxalate salts are preferable.
Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , 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 difluorooxalate borate, Lithium bis (oxalate) borate, Lithium tetrafluorooxalattophosphate, Lithium difluorobis (oxalate) phosphate or lithium Tris (oxalate) phosphate is particularly preferable because it has the effect of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, and the like. Further, the above-mentioned lithium salt may be used alone or in combination of two or more.

The total concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited, but is usually 8% by mass or more, preferably 8.5% by mass or more, more preferably 9% by mass, based on the total amount of the non-aqueous electrolyte solution. % Or more. The upper limit thereof is usually 18% by mass or less, preferably 17% by mass or less, and more preferably 16% by mass or less. When the total concentration of the electrolyte is within the above range, the electric conductivity becomes appropriate for battery operation, so that sufficient output characteristics tend to be obtained.

<1-7. Non-aqueous solvent>
Like a general non-aqueous electrolyte solution, the non-aqueous electrolyte solution of the present invention usually contains a non-aqueous solvent that dissolves the above-mentioned electrolyte as its main component. The non-aqueous solvent used here is not particularly limited, and a known organic solvent can be used. Examples of the organic solvent include saturated cyclic carbonates, chain carbonates, ether compounds, sulfone compounds and the like, but are not particularly limited thereto. These can be used alone or in combination of two or more.

<< 1-7-1. Saturated cyclic carbonate >>
Examples of the saturated cyclic carbonate include those having an alkylene group having 2 to 4 carbon atoms, and a saturated cyclic carbonate having 2 to 3 carbon atoms is preferably used from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation. ..
Examples of the saturated cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate and the like. Of these, ethylene carbonate and propylene carbonate are preferable, and ethylene carbonate, which is difficult to be oxidized and reduced, is more preferable. As the saturated 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 saturated cyclic carbonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. It is usually 3% by volume or more, preferably 5% 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, the stability with respect to the negative electrode, and the cycle characteristics of the non-aqueous electrolyte secondary battery can be easily set in a good range.
The upper limit is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. Within this range, the oxidation / reduction resistance of the non-aqueous electrolyte solution is improved, and the stability during high-temperature storage tends to be improved.
The volume% in the present invention means a value at 25 ° C. and 1 atm.

<< 1-7-2. Chain carbonate >>
As the chain carbonate, one having 3 to 7 carbon atoms is usually used, and in order to adjust the viscosity of the electrolytic solution in an appropriate range, a chain carbonate having 3 to 5 carbon atoms is preferably used.
Specifically, examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate, and methyl-n-propyl carbonate.
Examples thereof include n-butyl methyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, t-butyl ethyl carbonate and the like.

Of these, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate or methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate or ethylmethyl carbonate are particularly preferable. be.
In addition, chain carbonates having a fluorine atom (hereinafter, "fluorinated chain carbonate").
May be abbreviated as. ) 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 to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethylmethyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

As the fluorinated dimethyl carbonate derivative, fluoromethylmethyl carbonate,
Difluoromethylmethyl carbonate, trifluoromethylmethylcarbonate, bis (
Fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate and the like can be mentioned.
Examples of the fluorinated ethylmethyl carbonate derivative include 2-fluoroethylmethyl carbonate, ethylfluoromethylcarbonate, 2,2-difluoroethylmethylcarbonate, 2-fluoroethylfluoromethylcarbonate, ethyldifluoromethylcarbonate, and 2,2,2-tri. Examples thereof include fluoroethylmethyl carbonate, 2,2-difluoroethylfluoromethylcarbonate, 2-fluoroethyldifluoromethylcarbonate, and ethyltrifluoromethylcarbonate.

Examples of the fluorinated diethyl carbonate derivative include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, and ethyl- (2,2,2-trifluoro). Ethyl) carbonate, 2,
2-Difluoroethyl-2'-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2'-fluoroethyl carbonate, 2,2,2-trifluoroethyl- Examples thereof include 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 not particularly limited, but with respect to the total amount of the solvent of the non-aqueous electrolyte solution.
It is usually 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more. Further, it is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the content of the chain carbonate in the above range, the viscosity of the non-aqueous electrolyte solution is set in an appropriate range, the decrease in ionic conductivity is suppressed, and the output characteristics of the non-aqueous electrolyte secondary battery are in a good range. It becomes easy to do.

Further, by combining ethylene carbonate with a specific chain carbonate in a specific content, the battery performance can be remarkably improved.
For example, when dimethyl carbonate and ethyl methyl carbonate are selected as the specific chain carbonate, the content of ethylene carbonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but the non-aqueous electrolyte solution It is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less, preferably 40% by volume or less with respect to the total amount of the solvent, and the content of dimethyl carbonate is based on the total amount of the solvent of the non-aqueous electrolyte solution. Usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume.
The content of ethyl methyl carbonate is usually 20% by volume or more, preferably 30.
By volume or more, usually 50% by volume or less, preferably 45% by volume or less. By setting the content within the above range, high temperature stability is excellent and gas generation tends to be suppressed.

<< 1-7-3. Ether compound >>
As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms are preferable.
Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, and ethyl. (2-Fluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2) -Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoro) Ethyl) 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-tetrafluoroethyl-n -Propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (3,3,3-trifluoro) -N-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3)
3-Tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propyl ether , (N-propyl) (3-fluoro-n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2)
, 3,3-Tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3
3,3-Pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl)
Ether, (3-fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-)
Propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3-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-tetrafluoro-n-propyl)
2,2,3,3,3-pentafluoro-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) Methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2,2-trifluoro) Ethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) methane, (2) -Fluoroethoxy) (1,1
, 2,2-Tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-Tetrafluoroethoxy) Methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2)
2,2-Trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy (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, Examples thereof include di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 1 , 4-Dioxane and the like, and fluorinated compounds thereof.
Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether or diethylene glycol dimethyl ether have high solvation ability to lithium ions and have ionic dissociability. It is preferable in terms of improvement. Particularly preferred is dimethoxymethane, diethoxymethane or ethoxymethoxymethane because of its low viscosity and high ionic conductivity.

The content of the ether compound is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1% by volume or more, preferably 2% by volume or more in 100% by volume of the non-aqueous solvent.
More preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less,
More preferably, it is 20% by volume or less. When the content of the ether compound is within the above-mentioned preferable range, it is easy to secure the effect of improving the lithium ion dissociation degree of the chain ether and the effect of improving the ionic conductivity derived from the decrease in viscosity. Further, when the negative electrode active material is a carbonaceous material, the phenomenon that the chain ether is co-inserted together with the lithium ion can be suppressed, so that the input / output characteristics and the charge / discharge rate characteristics can be set in an appropriate range.

<1-7-4. Sulfone compounds>
The sulfone compound is not particularly limited to either a cyclic sulfone or a chain sulfone, but in the case of a cyclic sulfone, the number of carbon atoms is usually 3 to 6, preferably 3 to 5, and the chain sulfone is used. In the case of, a compound having 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms is preferable. The number of sulfonyl groups in one molecule of the sulfone compound is not particularly limited, but is usually 1 or 2.

Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones and hexamethylene sulfones which are monosulfone compounds; and trimethylene disulfones, tetramethylene disulfones and hexamethylene disulfones 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 are preferable. As the sulfolane derivative, one in which one or more of the hydrogen atoms bonded on the carbon atom constituting the sulfolane ring is 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-difluoromethyl sulfolane, 2-trifluoromethyl sulfolane, 3-trifluoromethyl sulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3
-(Trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane or 5-fluoro-3- (trifluoromethyl) sulfolane is preferable because of high ionic conductivity and high input / output.

Examples of the chain sulfone include 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, and n-. Butylmethyl sulfone, n-butylethyl sulfone, t-butylmethyl sulfone, t-butylethyl sulfone, monofluoromethylmethyl sulfone, difluoromethylmethyl sulfone, trifluoromethylmethyl sulfone, monofluoroethylmethyl sulfone, difluoroethylmethyl sulfone, Trifluoroethyl Methyl Sulfone, Pentafluoroethyl Methyl Sulfone, Ethyl Monofluoro Methyl Sulfone, Ethyl Difluoro Methyl Sulfone, Ethyl Trifluoro Methyl Sulfone, Perfluoro Ethyl Methyl Sulfone, Ethyl Trifluoro Ethyl Sulfone, Ethyl Pentafluoro Ethyl Sulfone, Di (Tri) Fluoroethyl) 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-
Examples thereof include n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, pentafluoroethyl-t-butyl sulfone and the like.

Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, 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 Monofluoro Methyl Sulfone, Ethyl Difluoro Methyl Sulfone, Ethyl Trifluoro Methyl Sulfone, Ethyl Trifluoro Ethyl Sulfone, Ethyl Pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone or trifluoromethyl-t -Butyl sulfone is preferable because it improves the high temperature storage stability of the electrolytic solution.

The content of the sulfone compound is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3% by volume or more, preferably 0, based on the total amount of the solvent of the non-aqueous electrolyte solution.
.. It is 5% by volume or more, more preferably 1% by volume or more, and usually 40% by volume or less, preferably 35% by volume or less, more preferably 30% by volume or less. When the content of the sulfone compound is within the above range, an electrolytic solution having excellent high temperature storage stability tends to be obtained.

<1-8. Auxiliary agent>
The non-aqueous electrolyte solution of the present invention may contain an auxiliary agent such as a compound having a cyano group, a diisocyanato compound, a carboxylic acid anhydride, and an overcharge inhibitor within the range in which the effect of the present invention is exhibited.

<< 1-8-1. Compounds with cyano groups >>
In the non-aqueous electrolyte solution of the present invention, the type of the compound having a cyano group that can be used as an auxiliary agent is not particularly limited as long as it is a compound having a cyano group in the molecule, but the following general formula ( The compound represented by 1) is more preferable. The method for producing the compound having a cyano group is not particularly limited, and a known method can be arbitrarily selected for production.

In the general formula (1), T represents an organic group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and U represents a substituent. It is a V-valent organic group having 1 to 10 carbon atoms which may have. V is an integer greater than or equal to 1 and V
When is 2 or more, T may be the same as or different from each other.
The molecular weight of the compound having a cyano group is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight of the compound having a cyano group is usually 40 or more, preferably 45 or more, more preferably 50 or more, and usually 200 or less, preferably 180 or more.
Below, it is more preferably 170 or less. Within this range, it is easy to secure the solubility of the compound having a cyano group in the non-aqueous electrolyte solution, and the effect of the present invention is likely to be exhibited.

Specific examples of the compound represented by the general formula (1) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile 2-methylbutyronitrile, trimethylnitrile, and the like. Hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenditrile, 2-pentenenitrile, 2-methyl-2- Pentennitrile, 3
-Methyl-2-pentenenitrile, 2-hexenenitrile, fluoronitrile, difluoronitrile, trifluoronitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3- Difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3' -A compound having one cyano group such as thiodipropionitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, pentafluoropropionitrile;

Marononitrile, Succinonitrile, Glutaronitrile, Adiponitrile, Pimeronitrile, Suberonitrile, Azelanitrile, Sevaconitrile, Undecandinitrile, Dodecandinitrile, Methylmalononitrile, Ethylmalononitrile, Isopropylmalononitrile, tert-butylmalononitrile, Methylsuccinonitrile , 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, trimethylsuccinonitrile,
Tetramethylsuccinonitrile, 3,3'-(ethylenedioxy) dipropionitrile,
Compounds having two cyano groups such as 3,3'-(ethylenedithio) dipropionitrile;
Compounds having three cyano groups such as 1,2,3-tris (2-cyanoethoxy) propane and tris (2-cyanoethyl) amines;

Cyanate compounds such as methyl cyanate, ethyl cyanate, propyl cyanate, butyl cyanate, pentyl cyanate, hexyl cyanate, heptyl cyanate;
Methyl thiocyanate, ethyl thiocyanate, propyl thiocyanate, butyl thiocyanate, pentyl thiocyanate, hexyl thiocyanate, heptyl thiocyanate, methanesulfonyl cyanide, ethane sulfonyl cyanide, propanesulfonyl cyanide, butane sulfonyl cyanide, pentan sulfonyl cyanide, hexane sulfonyl cyanide , Heptane sulfonyl cyanide, methyl sulph Russian nidate, ethyl sulph Russian nidate, propyl sulph russian nidate, butyl sulph russian nit, pentyl sulph russian sard, hexyl sulph russian sul, heptyl sul Sulfur-containing compounds such as frisinidat;

Cyanodimethylphosphin, cyanodimethylphosphin oxide, methyl cyanomethylphosphinate, methyl cyanomethyl phosphinate, dimethylphosphinic acid cyanide, dimethyl phosphinic acid cyanide, dimethyl cyanophosphonate, dimethyl cyano subphosphonate, cyanomethyl methyl phosphonate, methyl subphosphones. Phosphoric compounds such as cyanomethyl acid and cyanodimethyl phosphite;
Can be mentioned.

Of these, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, crotononitrile, 3-
Methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adipohnitrile, pimeronitrile, suberonitrile, azelanitrile, sevaconitrile, undecandinitrile or dodecandinitrile are preferred from the viewpoint of improving storage characteristics, and malononitrile, succinonitrile, glutaronitrile. , Adiponitrile, Pimeronitrile, Suberonitrile, Azelanitrile, Sevaconitrile, Undecandinitrile or Dodecandinitrile are more preferred.

As the compound having a cyano group, one kind may be used alone, or two or more kinds may be used together in any combination and ratio. The content of the compound having a cyano group 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. 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, and usually 1
It is contained in a concentration of 0% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. When the above range is satisfied, the effects such as low temperature output characteristics, charge / discharge rate characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

<1-8-2. Diisocianato compound>
In the non-aqueous electrolyte solution of the present invention, the diisocyanate compound that can be used as an auxiliary agent has a nitrogen atom only in the isocyanato group and two isocyanato groups in the molecule, and has the following general formula. The compound represented by (2) is preferable.

In the above general formula (2), Y is an organic group having a cyclic structure and having 1 or more and 15 or less carbon atoms. The carbon number of Y is usually 2 or more, preferably 3 or more, and more preferably 4 or more.
Further, it is usually 14 or less, preferably 12 or less, more preferably 10 or less, still more preferably 8 or less.
It is as follows.
In the above general formula (2), Y is particularly preferably an organic group having 4 to 15 carbon atoms and having one or more cycloalkylene groups having 4 to 6 carbon atoms or aromatic hydrocarbon groups. At this time,
The hydrogen atom on the cycloalkylene group may be substituted with a methyl group or an ethyl group. Since the diisocyanate compound having a cyclic structure is sterically bulky and is a molecule, side reactions on the positive electrode are unlikely to occur, and as a result, the cycle characteristics and the high temperature storage characteristics are improved. Here, the bonding site of the group bonded to the cycloalkylene group or the aromatic hydrocarbon group is not particularly limited and may be any of the meta-position, para-position and ortho-position, but the meta-position or para-position is the film. It is preferable that the cross-linking distance is appropriate because it is advantageous for lithium ion conductivity and easily lowers the resistance. Further, it is preferable that the cycloalkylene group is a cyclopentylene group or a cyclohexylene group from the viewpoint that the diisocyanate compound itself does not easily cause a side reaction, and that the cyclohexylene group causes resistance due to the influence of molecular motility. It is more preferable because it is easily lowered.

Further, it is preferable to have an alkylene group having 1 to 3 carbon atoms between the cycloalkylene group or the aromatic hydrocarbon group and the isocyanate group. Since it is sterically bulky due to having an alkylene group, side reactions on the positive electrode are less likely to occur. Further, when the alkylene group has 1 to 3 carbon atoms, the ratio of the isocyanate group to the total molecular weight does not change significantly, so that the effect of the present invention is remarkably likely to be exhibited.

The molecular weight of the diisocyanate compound represented by the general formula (2) is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The molecular weight is usually 80 or more, preferably 115 or more, more preferably 170 or more, and usually 300 or less, preferably 230 or less. Within this range, it is easy to secure the solubility of the diisocyanate compound in the non-aqueous electrolyte solution, and the effect of the present invention is likely to be exhibited.

Specific examples of the diisocyanate compound include, for example,
1,2-Diisocyanatocyclopentane, 1,3-Diisocyanatocyclopentane, 1
, 2-Diisocyanatocyclohexane, 1,3-Diisocyanatocyclohexane, 1,4
-Diisocyanatocyclohexane, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-2,2'- Diisocyanate, dicyclohexanemethane-2,4'-diisocyanate, dicyclohexanemethane-3,3'-
Cycloalkane ring-containing diisocyanates such as diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, etc .;

1,2-Phenylene diisocyanate, 1,3-phenylene diisocyanate, 1,4
-Phenylene diisocyanate, toluene-2,3-diisocyanate, tolylen-2,
4-Diisocyanate, Trilen-2,5-diisocyanate, Trilen-2,6-diisocyanate, Trilen-3,4-diisocyanate, Trilen-3,5-diisocyanate, 1,2-bis (isocyanatomethyl) benzene, 1, 3-Bis (isocyanatomethyl) benzene, 1,4-bis (isocyanatomethyl) benzene, 2,4-diisocyanatobiphenyl, 2,6-diisocyanatobiphenyl, 2,2'-diisocyanatobiphenyl, 3,3'-Diisocyanatobiphenyl, 4,4'-diisocyanato-2-methylbiphenyl, 4,4'-diisocyanato-3-methylbiphenyl, 4,4'-diisocyanato-
3,3'-dimethylbiphenyl, 4,4'-diisocyanatodiphenylmethane, 4,4'
-Diisocyanato-2-methyldiphenylmethane, 4,4'-diisocyanato-3-methyldiphenylmethane, 4,4'-diisocyanato-3,3'-dimethyldiphenylmethane, 1,5-diisocyanatonaphthalene, 1,8-diisocyanate Fragrances of naphthalene, 2,3-diisocyanatonaphthalene, 1,5-bis (isocyanatomethyl) naphthalene, 1,8-bis (isocyanatomethyl) naphthalene, 2,3-bis (isocyanatomethyl) naphthalene, etc. Ring-containing diisocyanates;
Can be mentioned.

Among these, 1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane , 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-phenylenediisocyanate, 1,3
-Phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,2-bis (
Isocyanatomethyl) benzene, 1,3-bis (isocyanatomethyl) benzene, 1,4
-Bis (isocyanatomethyl) benzene, 2,4-diisocyanatobiphenyl or 2,
6-Diisocyanatobiphenyl is preferred because it forms a denser complex film on the negative electrode, resulting in improved battery durability.

Among these, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,3-phenylenediocyanate, 1,4
-Phenylene diisocyanate, 1,2-bis (isocyanatomethyl) benzene, 1,3
-Because of the molecular symmetry of bis (isocyanatomethyl) benzene or 1,4-bis (isocyanatomethyl) benzene, a film advantageous for lithium ion conductivity is formed on the negative electrode.
As a result, battery characteristics such as low temperature output characteristics and cycle characteristics are further improved, which is more preferable.

As the above-mentioned diisocyanate compound, one kind may be used alone, or two or more kinds may be used in any combination and ratio.
The content of the diisocyanate compound that can be used in the non-aqueous electrolytic 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, but with respect to the total amount of the non-aqueous electrolytic solution of the present invention. Usually 0.001% by mass or more, preferably 0.01% by mass or more,
More preferably 0.1% by mass or more, further preferably 0.3% by mass or more, and usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, still more preferably 2.
It is less than mass%. When the content is within the above range, the battery characteristics such as low temperature output and cycle characteristics tend to be further improved.
The method for producing the diisocyanate compound is not particularly limited, and a known method can be arbitrarily selected for production. Further, a commercially available product may be used.

<1-8-3. Other auxiliaries>
Other known auxiliaries can be used for the non-aqueous electrolyte solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, and methoxyethyl-methyl carbonate; methyl-2-propynyl oxalate, ethyl-2-propynyl oxalate, bis (2). -Propinyl) Ogizarate,
2-Propinyl Acetate, 2-Propinyl Formate, 2-Propinyl Methacrylate, Di (2-Propinyl) Glutarate, Methyl-2-Propinyl Carbonate, Ethyl-
2-Propinyl Carbonate, Bis (2-Propinyl) Carbonate, 2-Butin-1,
4-Diyl-dimethanesulfonate, 2-butyne-1,4-diyl-dietansulfonate, 2-butyne-1,4-diyl-diformate, 2-butyne-1,4-diyl-diacetate, 2-butyne -1,4-diyl-dipropionate, 4-hexadiyne-1,6-
Diyl-dimethanesulfonate, 2-propynyl-methanesulfonate, 1-methyl-2
-Propinyl-methanesulfonate, 1,1-dimethyl-2-propinyl-methanesulfonate, 2-propynyl-ethanesulfonate, 2-propinyl-vinylsulfonate,
2-Propinyl-2- (diethoxyphosphoryl) acetate, 1-methyl-2-propynyl-2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propynyl-2
-Triple bond-containing compounds such as (diethoxyphosphoryl) acetate; 2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [ 5.5] Spiro compounds such as undecane; ethylene sulfide, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfane, sulfolene, ethylene sulfate, vinylene sulfate, diphenylsulfone, N, N -Sulfur-containing compounds such as dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, trimethylsilylmethylsulfate, trimethylsilylethylsulfate, 2-propynyl-trimethylsilylsulfate; 2-isocyanatoethyl acrylate, 2-
Isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2- (2-)
Isocyanate compounds such as isocyanatoethoxy) ethyl acrylate, 2- (2-isocyanatoethoxy) ethyl methacrylate, 2- (2-isocyanatoethoxy) ethyl crotonate; 1-methyl-2-pyrrolidinone, 1-methyl-2- Nitrogen-containing compounds such as piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane; fluorobenzene , Difluorobenzene, Hexafluorobenzene,
Benzotrifluoride, orthofluorotoluene, metafluorotoluene, parafluorotoluene, 1,2-bis (trifluoromethyl) benzene, 1-trifluoromethyl-
2-Difluoromethylbenzene, 1,3-bis (trifluoromethyl) benzene, 1-trifluoromethyl-3-difluoromethylbenzene, 1,4-bis (trifluoromethyl) benzene, 1-trifluoromethyl-4- Difluoromethylbenzene, 1,3,5-tris (trifluoromethyl) benzene, pentafluorophenylmethane sulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate,
Fluorophilic aromatic compounds such as pentafluorophenyl trifluoroacetate and methylpentafluorophenyl carbonate; tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris phosphate (trimethylsilyl), tris phosphate (trimethoxysilyl) ), Dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titaniumtetrakis (trimethylsiloxide), titanium Silane compounds such as tetrakis (triethylsiloxide); 2
-(Methanesulfonyloxy) propionic acid 2-propynyl, 2- (methanesulfonyloxy) propionic acid 2-methyl, 2- (methanesulfonyloxy) propionic acid 2-ethyl, methanesulfonyloxyacetic acid 2-propynyl, methanesulfonyloxyacetic acid Ester compounds such as 2-methyl, 2-ethyl methanesulfonyloxyacetic acid; lithium ethylmethyloxycarbonylphosphonate, lithium ethylethyloxycarbonylphosphonate,
Lithium Ethyl-2-propynyloxycarbonylphosphonate, Lithium Ethyl-1-
Lithium salts such as methyl-2-propynyloxycarbonylphosphonate, lithium ethyl-1,1-dimethyl-2-propynyloxycarbonylphosphonate; and the like. 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 other auxiliaries is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The content of the other auxiliary agent is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 0.2% by mass or more, based on the total amount of the non-aqueous electrolyte solution. It is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 1% by mass or less. Within this range, the effects of other auxiliaries are likely to be sufficiently exhibited, and high-temperature storage stability tends to be improved.

<2. Non-aqueous electrolyte secondary battery ＞
The non-aqueous electrolyte secondary battery of the present invention has a positive electrode having a current collector and a positive electrode active material layer provided on the current collector, and a negative electrode active material provided on the current collector and the current collector. It comprises a negative electrode having a layer and capable of storing and releasing ions, and the above-mentioned non-aqueous electrolytic solution of the present invention.

<2-1. Battery configuration>
The non-aqueous electrolyte secondary battery of the present invention has the same configuration as the conventionally known non-aqueous electrolyte secondary battery except for the above-mentioned non-aqueous electrolyte secondary battery of the present invention. Normally, the positive electrode and the negative electrode are laminated via a porous membrane (separator) impregnated with the non-aqueous electrolyte solution of the present invention, and these are cases (cases (separators).
It has a form housed in an exterior body). Therefore, the shape of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and may be any of a cylindrical type, a square type, a laminated type, a coin type, a large size, and the like.

<2-2. Non-aqueous electrolyte>
As the non-aqueous electrolyte solution, the above-mentioned non-aqueous electrolyte solution of the present invention is used. It is also possible to mix and use other non-aqueous electrolytic solutions with the non-aqueous electrolytic solution of the present invention as long as the gist of the present invention is not deviated.

<2-3. 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 metal ions. Specific examples include those having carbon as a constituent element such as a carbonaceous material, an alloy-based material, and the like. These are 1
The seeds may be used alone or in combination of two or more.

<< 2-3-1. Negative electrode active material >>
Examples of the negative electrode active material include carbonaceous materials and alloy-based materials as described above.
Examples of the carbonaceous material include (1) natural graphite, (2) artificial graphite, (3) amorphous carbon, and (4).
) Carbon-coated graphite, (5) graphite-coated graphite, (6) resin-coated graphite and the like.

(1) Examples of natural graphite include scaly graphite, scaly graphite, soil graphite, and / or graphite particles obtained by subjecting these graphites to treatments such as spheroidization and densification. Among these, spherical or ellipsoidal graphite subjected to a spherical treatment is particularly preferable from the viewpoint of particle filling 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 shear 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, impact compression, friction, and shearing force are applied to the raw material of natural graphite (1) introduced inside. A device that gives a mechanical action such as, etc. to perform the spheroidizing process is preferable. again,
A device having a mechanism for repeatedly giving a mechanical action by circulating a raw material is preferable.

For example, in the case of sphericalization processing using the above-mentioned device, the peripheral speed of the rotating rotor is set to 30 to 30 or more.
It is preferably set to 100 m / sec, more preferably 40 to 100 m / sec, and even more preferably 50 to 100 m / sec. Further, the spheroidizing treatment can be performed by simply passing the raw material through the device, but it is preferable to circulate or retain the inside of the device for 30 seconds or longer, and to circulate or stay in the device for 1 minute or longer. Is more preferable.

(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 25.
Examples thereof include those produced by graphitizing at a temperature in the range of 00 ° C. or higher, usually 3200 ° C. or lower, and pulverizing 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, mesocarbon microbeads, graphitizable carbonaceous material powders such as coke and tar,
A plurality of flat particles obtained by mixing a graphitizable binder such as pitch and a graphitizing catalyst, graphitizing, and pulverizing as necessary, are aggregated or bonded so that the orientation planes are non-parallel. Graphite particles can be mentioned.

(3) As the amorphous carbon, an easily graphitizable carbon precursor such as tar or pitch is used as a raw material.
Examples include amorphous carbon particles that have been heat-treated at least once in a temperature range that does not graphitize (range of 400 to 2200 ° C.), and amorphous carbon particles that have been heat-treated using a non-graphitizable carbon precursor such as resin as a raw material. Be done.

(4) Examples of the carbon-coated graphite include those obtained as follows. Natural graphite and / or artificial graphite are mixed with a carbon precursor which is an organic compound such as tar, pitch or resin, and heat-treated at least once in the range of 400 to 2300 ° C. The obtained natural graphite and / or artificial graphite is used as nuclear graphite and coated with amorphous carbon to obtain a carbon graphite complex. This carbon graphite composite is mentioned as carbon-coated graphite (4).
Further, the composite form may be a form in which the entire surface or a part of the surface of nuclear graphite is coated with amorphous carbon, or a form in which a plurality of primary particles are composited with carbon derived from the carbon precursor as a binder. good. In addition, benzene, toluene, methane, propane, hydrocarbon gases such as aromatic volatiles, etc. are reacted at high temperature with natural graphite and / or artificial graphite, and carbon is deposited on the graphite surface (CV).
The carbon-graphite complex can also be obtained by D).

(5) As the graphite-coated graphite, those obtained as follows can be mentioned. Natural graphite and / or artificial graphite are mixed with carbon precursors of easily graphitizable organic compounds such as tar, pitch and resin, and heat-treated at least once in the range of about 2400 to 3200 ° C. The obtained natural graphite and / or artificial graphite is used as nuclear graphite, and the entire surface or a part of the surface of the graphite is coated with graphite to obtain graphite-coated graphite (5).

(6) The resin-coated graphite is prepared by mixing, for example, natural graphite and / or artificial graphite with a resin or the like, and 4
It is obtained by using natural graphite and / or artificial graphite obtained by drying at a temperature of less than 00 ° C. as nuclear graphite and coating the nuclear graphite with a resin or the like.
Further, as the carbonaceous materials of (1) to (6) described above, one kind may be used alone, or two or more kinds may be used in any combination and ratio.

Examples of the organic compounds such as tar, pitch and resin used for the carbonaceous materials (2) to (5) above include coal-based heavy oil, DC-based heavy oil, decomposition-based petroleum heavy oil, and aromatic hydrocarbons. , 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 dissolving it in a small molecule 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.
Next, the alloy-based material used as the negative electrode active material is a simple substance of lithium, a simple substance metal and alloy forming a lithium alloy, or an oxide thereof, if lithium can be occluded and released.
It may be any compound such as a carbide, a nitride, a silicide, a sulfide or a phosphide, and is not particularly limited. The single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably single metals of aluminum, silicon and tin, and these. An alloy or compound containing atoms,
More preferably, elemental metals of silicon and tin and alloys or compounds containing these atoms, etc.
It contains silicon or tin as a constituent element. These may be used alone or in combination of two or more in any combination and ratio.

<<< Metal particles that can be alloyed with Li >>>
When a single metal and alloy forming a lithium alloy or a compound such as an oxide, a carbide, a nitride, a silide, a sulfide or a phosphate thereof is used as a negative electrode active material, the metal that can be alloyed with Li is a metal that can be alloyed with Li. It is a particle form. Methods for confirming that the metal particles are metal particles that can be alloyed with Li include identification of the metal particle phase by X-ray diffraction, observation and element analysis of the particle structure by an electron microscope, and elements by fluorescent X-ray. Analysis etc. can be mentioned.

As the metal particles that can be alloyed with Li, any conventionally known metal particles can be used.
From the viewpoint of the capacity and cycle life of the non-aqueous electrolyte secondary battery, the metal particles may be, for example, Fe.
Co, Sb, Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, P, S, V, M
It is preferably a metal selected from the group consisting of n, As, Nb, Mo, Cu, Zn, Ge, In, Ti and W or a compound thereof. 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 a Si metal compound is 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 of the battery. In the present specification, Si or Si metal compounds are collectively referred to as Si compounds. Specific examples of the Si compound include SiOx, SiNx, SiCx, and SiZxOy.
(Z = C, N) and the like. The Si compound is preferably a Si metal oxide, and is S.
The i-metal oxide is SiOx in the general formula. This general formula SiOx is Si (Si
It is obtained from SiO2) and metal Si (Si) as raw materials, and the value of x is usually 0≤x <2.
Is. SiOx has a large theoretical capacity as compared with graphite, and amorphous Si or nano-sized Si crystals can easily move in and out of alkaline ions such as lithium ions, so that a high capacity can be obtained.

The Si metal oxide is specifically represented as SiOx, where x is 0 ≦ x <2, more preferably 0.2 or more and 1.8 or less, still more preferably 0.4. More than 1.6 or less,
Particularly preferably, it is 0.6 or more and 1,4 or less. Within this range, the battery has a high capacity, and at the same time, it is possible to reduce the irreversible capacity due to the combination of Li and oxygen.
-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, from the viewpoint of the cycle life of the non-aqueous electrolyte secondary battery. As described above, it is more preferably 0.3 μm or more, 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, the volume expansion due to the discharge of the rechargeable battery is reduced, and good cycle characteristics can be obtained while maintaining the charge / discharge capacity.
The average particle size (d50) can be obtained by a laser diffraction / scattering type particle size distribution measuring method or the like.

-BET method specific surface area of metal particles that can be alloyed with Li The specific surface area obtained by the BET method of metal particles that can be alloyed with Li is usually 0.5 to 60 m.
It is 2 / g, preferably 1 to 40 m2 / 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 the discharge capacity of the battery are high.
Lithium is quickly charged and discharged in high-speed charging and discharging, and is preferable because it has excellent rate characteristics.

-Amount of oxygen contained in metal particles that can be alloyed with Li The amount of oxygen contained in metal particles that can be alloyed with Li is not particularly limited, but is usually 0.01 to 8% by mass and 0.05 to 5% by mass. % Is preferable. The oxygen distribution state in the particle may be present near the surface, inside the particle, or uniformly present in the particle, but it is particularly preferable that the oxygen is present near the surface. When the oxygen content of the metal particles that can be alloyed with Li is within the above range, the strong bond between the metal particles and O suppresses the volume expansion due to the secondary charge and discharge of the non-aqueous electrolyte solution, and the cycle characteristics are excellent. preferable.

<<< Negative electrode active material containing metal particles and graphite particles that can be alloyed with Li >>>
The negative electrode active material may contain Li, metal particles that can be alloyed, and graphite particles. The negative electrode active material may be a mixture in which Li, alloyable metal particles, and graphite particles are mixed in the state of mutually independent particles, or Li and alloyable metal particles may be present on the surface of the graphite particles and the graphite particles. / Or it may be a complex existing inside.

The composite of the metal particles that can be alloyed with Li and the graphite particles (also referred to as composite particles) is particularly limited as long as the particles contain the metal particles that can be alloyed with Li and the graphite particles. However, it is preferably particles in which metal particles and graphite particles that can be alloyed with Li are integrated by physical and / or chemical bonds. In a more preferable form, the metal particles and graphite particles that can be alloyed with Li are present in the particles in a state in which the solid components are dispersed in the particles to the extent that they are present at least on the surface of the composite particles and inside the bulk. And they are physical and /
Alternatively, it is a form in which graphite particles are present in order to integrate them by chemical bonding. A more specific preferred form is a composite material composed of at least Li and alloyable metal particles and graphite particles, in which the graphite particles, preferably natural graphite, have a curved structure and have a folded structure. In addition, it is a composite material (negative electrode active material) characterized in that metal particles that can be alloyed with Li are present in the gaps in the structure. Further, the gap may be a void, and a substance such as amorphous carbon, a graphitic substance, a resin, or the like that buffers the expansion and contraction of metal particles that can be alloyed with Li exists in the gap. You may.

-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 0.1% by mass or more, preferably 0. .5% by mass or more, more preferably 1
.. It is 0% by mass or more, more preferably 2.0% by mass or more. Also, usually 99% by mass or less,
It is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass.
Below, it is more preferably 25% by mass or less, still more preferably 20% by mass or less, particularly preferably 15% by mass or less, and most preferably 10% by mass or less. Within this range, S
i It is preferable in that it is possible to control side reactions on the surface and obtain a sufficient capacity in a non-aqueous electrolyte secondary battery.

(Coverage)
The negative electrode active material of the present invention may be coated with a carbonaceous substance or a graphitic substance. Of these, coating with an amorphous carbonaceous material is preferable from the viewpoint of lithium ion acceptability. This coverage is usually 0.5% or more and 30% or less, preferably 1% or more and 25% or less, and more preferably 2% or more and 20% or less. If this coverage is too large, the amorphous carbon portion of the carbonaceous material increases, and the reversible capacity when the battery is assembled tends to decrease. If the coverage is too small, the core carbonaceous material is not uniformly coated with amorphous carbon and strong granulation is not performed, and the particle size tends to be too small when pulverized after firing.

The finally obtained coverage (content rate) of the carbide derived from the organic compound of the negative electrode active material is
It can be calculated by the following formula from the amount of the negative electrode active material, the amount of the organic compound, and the residual coal ratio measured by the micro method based on JIS K 2270.
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 compound x residual coal 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 this internal gap ratio is too small, the amount of liquid in the particles of the negative electrode active material tends to decrease in the non-aqueous electrolyte secondary battery, and the charge / discharge characteristics tend to deteriorate. On the other hand, if the internal porosity is too large, the interparticle gap is small when the electrode is used, and the diffusion of the non-aqueous electrolyte solution tends to be insufficient. Further, the voids are filled with substances such as amorphous carbon, graphite, resin, etc. that buffer the expansion and contraction of metal particles that can be alloyed with Li. You may.

<Construction and manufacturing method of negative electrode>
Any known method can be used for producing the negative electrode as long as the effect of the present invention is not significantly impaired. For example, a binder, a solvent, and if necessary, a thickener, a conductive material, a filler, etc. are added to a negative electrode active material to form a slurry, which is applied to a current collector, dried, and then pressed to form a slurry. Can be done.

Further, the alloy-based material 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, the above-mentioned negative electrode is usually used by 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.

Examples of the material of the negative electrode current collector include steel, copper, 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.
Hereinafter, it is preferably 50 μm or less. If the thickness of the negative electrode current collector is too thick, the capacity of the entire non-aqueous electrolyte secondary battery may decrease too much, and conversely, if it is too thin, handling may become difficult.

In order to improve the effect of binding to 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, abrasive cloth with abrasive particles fixed, a grindstone, and emeri buff.
Examples thereof include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method in which the surface of a current collector is polished with a wire brush or the like provided with a steel wire or the like.

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 that is a combination of a negative electrode active material and a conductive material.
The content of the negative electrode active material in the negative electrode material is usually 70% by mass or more, particularly 75% by mass or more.
Further, it is 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 material is relatively insufficient, so that electricity as the negative electrode is used. 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
It is preferably mass% or more, preferably 5% by mass or more, and usually 30% by mass or less, preferably 25% by mass or less. If the content of the conductive material is too low, the conductivity tends to be insufficient.
If it is too large, the content of the negative electrode active material or the like is relatively insufficient, and 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 material can be used as long as it is a material that is safe for the solvent and the electrolytic solution used at the time of manufacturing the electrode. Examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer and the like. 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, preferably 1 part by mass or more, and usually 10 parts by mass or less with respect to 100 parts by mass of the negative electrode material.
It is preferably less than or equal to parts by mass. 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 or the like is relatively insufficient.
Battery capacity and conductivity tend to be insufficient. When two or more binders are used in combination, the total amount of the binders may satisfy the above range.

Thickeners used for the negative electrode include carboxymethyl cellulose, methyl cellulose,
Examples thereof include hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and the like. These may be used alone or 2
The seeds or more may be used in any combination and ratio. The thickener may be used as needed, but when used, the content of the thickener in the negative electrode active material layer is usually 0.5% by mass.
As mentioned above, it is preferable to use it in the range of 5% by mass or less.

The slurry for forming the negative electrode active material layer is prepared by mixing the negative electrode active material with a conductive material, 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 an organic solvent such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone should be used in combination with water in a range of 30% by mass or less. You can also. Examples of the organic solvent include cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and the like.
Examples include aromatic hydrocarbons such as anisole, toluene and xylene, and alcohols such as butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, N,
Linear amides such as 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, and a negative electrode is obtained. 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. When 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 of the non-aqueous electrolyte secondary battery increases, and the current collector / negative electrode High current density charge / discharge characteristics may deteriorate due to a decrease in the permeability of the non-aqueous electrolyte solution near the active material interface. Further, if it is 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.

<2-4. Positive electrode>
The positive electrode used in the non-aqueous electrolyte secondary battery of the present invention will be described below.
<< 2-4-1. Positive electrode active material >>
The positive electrode active material used for the positive electrode will be described below.

(1) Composition Examples of the positive electrode active material include transition metal oxides containing lithium cobaltate and at least Ni and Co, and 50 mol% or more of the transition metals are Ni and Co, and electrochemically. There is no particular limitation as long as it can store and release metal ions, but those capable of storing and releasing lithium ions electrochemically are preferable, and they contain lithium and at least Ni and Co, and 50 mol of the transition metal. A transition metal oxide in which% or more is Ni and Co is more preferable. Ni
And Co have a redox potential suitable for use as a positive electrode material for a secondary battery, and are suitable for high-capacity applications.

The transition metal components of the lithium transition metal oxide include Ni and Co as essential elements, but other metals such as Mn, V, Ti, Cr, Fe, Cu, Al, Mg, Zr and E.
r and the like are mentioned, and Mn, Ti, Fe, Al, Mg, Zr and the like are preferable. Specific examples of the lithium transition metal oxide include, for example, LiCoO ₂ , LiNi _0.85 Co _0.10 Al ₀ .
_{.. 05} O ₂ , LiNi _0.80 Co _0.15 Al _0.05 O2, LiNi _0.33 Co _{0
.. 33} Mn _0.33 O ₂ , Li _1.05 Ni _0.33 Mn _0.33 Co _0.33 O ₂ , L
iNi _0.5 Co _0.2 Mn _0.3 O ₂ , Li _1.05 Ni _0.50 Mn _0.29 Co _{0
.. 21} O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn
_0.1 O2 and the like can be mentioned.

Above all, it is preferable that it is a transition metal oxide represented by the following composition formula (4).
Li _a1 Ni _b1 Co _c1 M _d1 O ₂ ... (4)
(In the formula (4), 0.9 ≦ a1 ≦ 1.1, 0.3 ≦ b1 ≦ 0.9, 0.1 ≦ c1 ≦ 0.5,
A numerical value of 0.0 ≦ d1 ≦ 0.5 is shown, and 0.5 ≦ b1 + c1 and b1 + c1 + d1 = 1 are satisfied. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er. )
In the composition formula (4), it is preferable to show a numerical value of 0.1 ≦ d1 ≦ 0.5.

Since the composition ratio of Ni and Co and the composition ratio of other metal species are as specified, it is difficult for the transition metal to elute from the positive electrode, and even if it elutes, Ni and Co can be contained in the non-aqueous secondary battery. This is because the adverse effect of is small.
Above all, it is more preferable that it is a transition metal oxide represented by the following composition formula (5).
Li _a2 Ni _b2 Co _c2 M _d2 O ₂ ... (5)
(In the formula (5), 0.9 ≦ a2 ≦ 1.1, 0.3 ≦ b2 ≦ 0.9, 0.1 ≦ c2 ≦ 0.5,
The numerical values of 0.0 ≦ d2 ≦ 0.5 are shown, and c2 ≦ b2 and 0.6 ≦ b2 + c2 and b2 + c2.
Satisfy + d2 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er. )
In the composition formula (5), it is preferable to show a numerical value of 0.1 ≦ d2 ≦ 0.5.

Since Ni and Co are the main components and the composition ratio of Ni is the same as or larger than the composition ratio of Co, it is stable and takes out a high capacity when used as a positive electrode of a non-aqueous secondary battery. Because it is possible.
Above all, it is more preferable that it is a transition metal oxide represented by the following composition formula (6).
Li _a3 Ni _b3 Co _c3 M _d3 O ₂ ... (6)
(In the formula (6), 0.9 ≦ a3 ≦ 1.1, 0.35 ≦ b3 ≦ 0.9, 0.1 ≦ c3 ≦ 0.5
, 0.0 ≦ d3 ≦ 0.5, c3 <b3 and 0.6 ≦ b3 + c3 and b3 + c
Satisfy 3 + d3 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er. )
In the composition formula (6), it is preferable to show a numerical value of 0.1 ≦ d3 ≦ 0.5.

Above all, the transition metal oxide represented by the following composition formula (7) is particularly preferable.
Li _a4 Ni _b4 Co _c4 M _d4 O ₂ ... (7)
(In formula (7), 0.9 ≦ a4 ≦ 1.1, 0.5 ≦ b4 ≦ 0.9, 0.1 ≦ c4 ≦ 0.2,
The numerical values of 0.0 ≦ d4 ≦ 0.3 are shown, and c4 <b4 and 0.7 ≦ b4 + c4 and b4 + c4.
Satisfy + d4 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er. )
In the composition formula (7), it is preferable to show a numerical value of 0.1 ≦ d4 ≦ 0.3.

This is because the above composition makes it possible to take out a particularly high capacity when used as a positive electrode of a non-aqueous secondary battery.
Further, two or more of the above positive electrode active materials may be mixed and used. Similarly, at least one of the above positive electrode active materials may be mixed with another positive electrode active material for use. Examples of other positive electrode active materials include transition metal oxides, transition metal phosphoric acid compounds, transition metal silicic acid compounds, and transition metal boric acid compounds not listed above.

Of these, a lithium manganese composite oxide having a spinel-type structure and a lithium-containing transition metal phosphoric acid compound having an olivine-type structure are preferable. Specifically, as a lithium manganese composite oxide having a spinel-type structure, LiMn ₂ O ₄ , LiMn _1.8 Al _0.2 O ₄ , Li.
Mn _1.5 Ni _0.5 O ₄ and the like can be mentioned. This is because the structure is the most stable, oxygen is less likely to be released even when the non-aqueous electrolyte secondary battery is abnormal, and the safety is excellent.

Further, as the transition metal of the lithium-containing transition metal phosphoric acid compound, V, Ti, Cr, Mn, etc.
Fe, Co, Ni, Cu and the like are preferable, and specific examples thereof include LiFePO ₄ , Li.
₃ Fe ₂ (PO ₄ ) ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , manganese phosphates such as LiMnPO ₄ , and transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds. Some are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, C
Examples thereof include those substituted with other metals such as u, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and W.
Among them, lithium iron-phosphoric acid compounds are preferable, because iron is an extremely inexpensive metal with abundant resources and is less harmful. That is, among the above specific examples, LiFePO ₄ can be mentioned as a more preferable specific example.

(2) Surface coating A substance having a composition different from that of the substance constituting the main positive electrode active material (hereinafter, appropriately referred to as “surface adhering substance”) may be used on the surface of the positive electrode active material. .. Examples of surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, etc. Examples thereof include sulfates such as calcium sulfate and aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.

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

The mass of the surface-adhering substance adhering to the surface of the positive electrode active material is relative to the mass of the positive electrode active material.
It is preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more. Further, it is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less.
The surface-adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte solution on the surface of the positive electrode active material, and can improve the battery life. Further, when the amount of adhesion is within the above range, the effect can be sufficiently exhibited, and the resistance does not easily increase without obstructing the ingress and egress of lithium ions.

<< 2-4-2. Positive electrode structure and manufacturing method >>
Hereinafter, the configuration of the positive electrode used in the present invention and the method for producing the same will be described.
(How to make a positive electrode)
The positive electrode is produced by forming a positive electrode active material layer containing positive electrode active material particles and a binder on a current collector. The positive electrode using the positive electrode active material can be produced by any known method. For example, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener are mixed in a dry manner to form a sheet, which is then pressure-bonded to a positive electrode current collector, or these materials are dissolved in a liquid medium. Alternatively, a positive electrode can be obtained by forming a positive electrode active material layer on the current collector by dispersing the slurry as a slurry, applying the slurry to the positive electrode current collector, and drying the mixture.

The content of the positive electrode active material in the positive electrode active material layer is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and preferably 99.9% by mass or less. Yes, 99% by mass or less is more preferable. When the content of the positive electrode active material is within the above range, a sufficient electric capacity can be secured. Further, the strength of the positive electrode is also sufficient. As the positive electrode active material powder in the present invention, one type may be used alone, or two or more types having different compositions or different powder physical characteristics may be used in combination in any combination and ratio. When two or more kinds of active substances are used in combination, it is preferable to use the composite oxide containing lithium and manganese as a component of the powder. Cobalt or nickel is an expensive metal with a small amount of resources, and it is cheaper because it is not preferable in terms of cost because the amount of active material used is large in large batteries that require high capacity such as for automobile applications. This is because it is desirable to use manganese as a main component as a transition metal.

(Conductive material)
As the conductive material, a known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; carbonaceous materials such as amorphous carbon such as needle coke. It should be noted that one of these may be used alone, or two or more of them may be used in any combination and ratio.

The content of the conductive material in the positive electrode active material layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 1% by mass or more, and preferably 50% by mass or less. It is more preferably 30% by mass or less, and further preferably 15% by mass or less. When the content is within the above range, sufficient conductivity can be ensured. Furthermore, it is easy to prevent a decrease in battery capacity.

(binder)
The binder used for producing the positive electrode active material layer is not particularly limited as long as it is a material stable to the non-aqueous electrolyte solution and the solvent used for producing the electrode.
In the case of the coating method, the material is not particularly limited as long as it is a material that is dissolved or dispersed in the liquid medium used in the manufacture of the electrode, but specific examples thereof include polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, aromatic polyamide, and cellulose. , Resin-based polymers such as nitrocellulose; SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), fluororubber, isoprene rubber, butadiene rubber, ethylene /
Rubber-like polymer such as propylene rubber; styrene / butadiene / styrene block copolymer or hydrogen additive thereof, EPDM (ethylene / propylene / diene ternary copolymer), styrene / ethylene / butadiene / ethylene copolymer, styrene・ Thermoplastic elastomeric polymer such as isoprene / styrene block copolymer or its hydrogenated product; Syndiotactic-
Soft resinous polymers such as 1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF),
Fluorine-based polymers such as polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymer; polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions) can be mentioned. In addition, one of these substances may be used alone, or two or more kinds may be used in arbitrary combinations and ratios.

The content of the binder in the positive electrode active material layer is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, and preferably 80% by mass or less. 60% by mass or less is more preferable, 40% by mass or less is further preferable, and 10% by mass or less is particularly preferable. When the ratio of the binder is within the above range, the positive electrode active material can be sufficiently retained and the mechanical strength of the positive electrode can be ensured, so that the battery performance such as cycle characteristics is improved. Furthermore, it also leads to avoiding a decrease in battery capacity and conductivity.

(Liquid medium)
The liquid medium used to prepare the slurry for forming the positive electrode active material layer is a solvent capable of dissolving or dispersing the positive electrode active material, the conductive material, the binder, and the thickener used as needed. If there is, the type is not particularly limited, and either an aqueous solvent or an organic solvent may be used.

Examples of the aqueous solvent include water, a mixed medium of alcohol and water, and the like. Examples of organic solvents include aliphatic hydrocarbons such as hexane; benzene, toluene, xylene, etc.
Aromatic hydrocarbons such as methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as methyl acetate and methyl acrylate; diethylenetriamine, N, N-dimethylaminopropylamine Amines such as; ethers such as diethyl ether and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide;
Examples thereof include aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide. In addition, these may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

(Thickener)
When an aqueous medium is used as the liquid medium for forming the slurry, it is preferable to use a thickener and a latex such as styrene-butadiene rubber (SBR) to form the slurry. Thickeners are typically used to adjust the viscosity of the slurry.
The thickener is not limited as long as the effect of the present invention is not significantly limited, but specifically, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof. And so on. These may be used alone or in combination of two or more in any combination and ratio.

When a thickener is used, the ratio of the thickener to the positive electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 0.6% by mass or more. Preferably
Further, it is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less. Within the above range, the coatability is good, and the ratio of the active material to the positive electrode active material layer is sufficient, so that the problem of battery capacity decrease and the resistance between the positive electrode active materials increase. It makes it easier to avoid problems.

(Consolidation)
The positive electrode active material layer obtained by applying and drying the slurry to the current collector is preferably consolidated by a hand press, a roller press, or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is preferably 1 g · cm ^-3 or more, more preferably 1.5 g · cm ^-3 or more, particularly preferably 2 g · cm ^-3 or more, and preferably 4 g · cm ^-3 or less. 3.5 g · cm ^-3 or less is more preferable, and 3 g · cm ^-3 or less is particularly preferable.
When the density of the positive electrode active material layer is within the above range, the permeability of the non-aqueous electrolyte solution to the vicinity of the current collector / active material interface does not decrease, and the charge / discharge characteristics are particularly good at a high current density. Become. moreover,
It becomes difficult for the conductivity between active materials to decrease, and it becomes difficult for the battery resistance to increase.

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

Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foamed metal, etc. in the case of metal material, and carbon plate in the case of carbonaceous material. Examples include a carbon thin film and a carbon column. Of these, a metal thin film is preferable.
The thin film may be formed in a mesh shape as appropriate.
The thickness of the current collector is arbitrary, but is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, preferably 1 mm or less, more preferably 100 μm or less, and further preferably 50 μm or less. preferable. When the thickness of the current collector is within the above range, the strength required for the current collector can be sufficiently secured. Further, the handleability is also good.
The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but (thickness of the active material layer on one side immediately before the injection of the non-aqueous electrolyte solution) / (thickness of the current collector) is preferable. It is 150 or less, more preferably 20 or less, particularly preferably 10 or less, preferably 0.1 or more, more preferably 0.4 or more, and particularly preferably 1 or more.
When the ratio of the thickness of the current collector to the positive electrode active material layer is within the above range, the current collector is less likely to generate heat due to Joule heat during high current density charging / discharging. Further, it becomes difficult to increase the volume ratio of the current collector to the positive electrode active material, and it is possible to prevent a decrease in battery capacity.

(Electrode area)
From the viewpoint of increasing the output and stability at high temperature, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case. Specifically, the total area of the electrodes of the positive electrode with respect to the surface area of the exterior of the non-aqueous electrolyte secondary battery is preferably 20 times or more, and more preferably 40 times or more in terms of area ratio. In the case of a bottomed square shape, the outer surface area of the outer case is the total area calculated from the dimensions of the length, width, and thickness of the case part filled with power generation elements excluding the protrusions of the terminals. .. In the case of a bottomed cylindrical shape, the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material.
In a structure in which positive electrode mixture layers are formed on both sides via a current collector foil, it means the total area of each surface calculated separately.

(Discharge capacity)
When the non-aqueous electrolyte solution of the present invention is used, the electric capacity of the battery element housed in one battery exterior of the non-aqueous electrolyte secondary battery (electrical capacity when the battery is discharged from a fully charged state to a discharged state). ) Is 1 amper hour (Ah) or more, which is preferable because the effect of improving the low temperature discharge characteristics is large. Therefore, the positive electrode plate has a fully charged discharge capacity, preferably 3 Ah (ampere hour), more preferably 4 Ah or more, preferably 100 Ah or less, more preferably 70 Ah or less, and particularly preferably 50 Ah. Design to be as follows.

Within the above range, the voltage drop due to the electrode reaction resistance does not become too large when a large current is taken out, and deterioration of power efficiency can be prevented. Furthermore, the temperature distribution due to the internal heat generation of the battery during pulse charging / discharging does not become too large, the durability of repeated charging / discharging is inferior, and the heat dissipation efficiency is poor against sudden heat generation at the time of abnormalities such as overcharging and internal short circuit. It is possible to avoid the phenomenon of becoming.

(Thickness of positive electrode plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity, high output, and high rate characteristics,
The thickness of the positive electrode active material layer obtained by subtracting the thickness of the current collector is preferably 10 μm or more, more preferably 20 μm or more, preferably 200 μm or less, and 100 μm with respect to one side of the current collector.
More preferably m or less.

<2-5. 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 electrolytic solution of the present invention is usually used by impregnating this separator.
The material and shape of the separator are not particularly limited, and any known separator can be used as long as the effect of the present invention is not significantly impaired. Among them, resins, glass fibers, inorganic substances and the like formed of a material stable to the non-aqueous electrolytic solution of the present invention are used, and a porous sheet or a non-woven fabric-like material having excellent liquid retention property is used. Is preferable.

As the material of the resin and the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyether sulfone, glass filter 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 them 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, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin than the above range, the insulating property and the mechanical strength may be deteriorated. 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, preferably 45%.
The above is more preferable, and usually 90% or less, 85% or less is preferable, and 75% or less is more preferable. If the porosity is too smaller 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 is lowered and the insulating property tends to be lowered.

The average pore diameter of the separator is also arbitrary, but is usually 0.5 μm or less, 0.2 μm.
The following is preferable, and it is usually 0.05 μm or more. If the average hole diameter exceeds the above range, a short circuit is likely to occur. Further, if it is 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 have a particle shape or a fiber shape. Things are used.

As the form, a thin film such as a non-woven fabric, a woven fabric, 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 independent thin film shape, a separator obtained by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle size of less than 1 μm may be formed on both sides of the positive electrode by using a fluororesin as a binder to form a porous layer.

<2-6. Battery design>
[Electrode group]
The electrode group has a laminated structure in which the above-mentioned positive electrode plate and the above-mentioned negative electrode plate are interposed via the above-mentioned separator.
And any of the above-mentioned positive electrode plate and negative electrode plate having a structure in which the above-mentioned positive electrode plate and the negative electrode plate are spirally wound via the above-mentioned 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.
80% or less is preferable. When the electrode group occupancy rate is lower 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.

[Current collector structure]
The current collecting structure is not particularly limited, but in order to more effectively improve the discharge characteristics by the non-aqueous electrolyte solution of the present invention, it is necessary to use a structure that reduces the resistance of the wiring portion and the joint portion. preferable. When the internal resistance is reduced in this way, the effect of using the non-aqueous electrolytic solution of the present invention is particularly well exhibited.

When the electrode group has the above-mentioned laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminals is preferably used. When the area of one electrode becomes large, the internal resistance becomes large. Therefore, it is also preferably used to reduce the resistance by providing a plurality of terminals in the electrode. In the case where the electrode group has the above-mentioned winding structure, the internal resistance can be reduced by providing a plurality of lead structures on the positive electrode and the negative electrode and bundling them in the terminals.

[Exterior case]
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, a metal such as stainless steel, aluminum or an aluminum alloy, a magnesium alloy, or a laminated film of a resin and an aluminum foil (
Laminated film) is used. From the viewpoint of weight reduction, aluminum or an aluminum alloy metal or a laminated film is preferably used.

In the outer case using the metals, the metals are welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed and sealed structure, or the metal is caulked using the metals via a resin gasket. There is something to do. Examples of the outer case using the laminated film include those having a hermetically sealed structure by heat-sealing resin layers to each other.
In order to improve the sealing property, a resin different from the resin used for the laminated film may be interposed between the resin layers. In particular, when the resin layer is heat-sealed via the current collecting terminal to form a closed structure, the metal and the resin are bonded to each other. Resin is preferably used.

[Protective element]
As the above-mentioned protection element, PTC (Po) whose resistance increases when abnormal heat generation or excessive current flows.
Examples include a system Temperature Coefficient), a thermal fuse, a thermistor, and a valve (current cutoff valve) that shuts off the current flowing through the circuit due to a sudden rise in battery internal pressure or internal temperature during abnormal heat generation. It is preferable to select the protective element under conditions that do not operate under normal use with a high current, and from the viewpoint of high output, 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 of the present invention is usually configured by accommodating the above-mentioned non-aqueous electrolyte, negative electrode, positive electrode, separator and the like inside the exterior. There are no restrictions on this exterior body, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired.
Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron,
Stainless steel, aluminum or an alloy thereof, nickel, titanium and the like are used.
Further, the shape of the exterior body is also arbitrary, and may be, for example, any of a cylindrical type, a square shape, a laminated type, a coin type, a large size, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Reference Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.
The structural formulas of compounds 1 to 8 used in this example and comparative example are shown below.

<Example 1-1, Comparative Examples 1-1 to 1-5>
[Preparation of positive electrode]
Lithium-nickel-cobalt-manganese composite oxide (LiNi _0.
5 Mn _0.3 Co _0.2 O ₂ ) 90% by mass and 7% by mass of acetylene black as a conductive material
And 3% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to obtain a positive electrode.

[Manufacturing of negative electrode]
98 parts by mass of natural graphite, 1 part by mass of aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose 1% by mass) and aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber) as a thickener and binder. 50% by mass) 1 part by mass was added and mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and then pressed to obtain a negative electrode.

[Preparation of non-aqueous electrolyte solution]
Ethylene carbonate (EC), ethyl methyl carbonate (in a dry argon atmosphere)
In a mixture of EMC) and diethyl carbonate (DEC) (volume volume ratio 3: 4: 3), 1.2 mol / L (concentration in a non-aqueous electrolyte solution) of sufficiently dried LiPF ₆ was dissolved.
In addition, vinylene carbonate (VC) and monofluoroethylene carbonate (FEC)
And 2.0% by mass each were added (this is referred to as reference electrolyte 1). A non-aqueous electrolytic solution was prepared by adding the compounds shown in Table 1 below as additives to the reference electrolytic solution 1. However, Comparative Example 1-1 is the reference electrolyte 1 itself. The "content (% by mass)" in the table is
It is the content when the reference electrolytic solution 1 is 100% by mass.

[Manufacturing of non-aqueous electrolyte secondary batteries]
The above positive electrode, negative electrode, and polyethylene separator were laminated in this order of negative electrode, separator, and positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminated film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer while projecting the positive electrode and negative electrode terminals, the prepared non-aqueous electrolyte solution is placed in the bag. Was injected into the battery and vacuum-sealed to prepare a laminated non-aqueous electrolyte secondary battery.

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
In a constant temperature bath at 25 ° C, a non-aqueous electrolyte secondary battery is charged with a constant current of 0.05 C (1 C means a current value that takes 1 hour to charge or discharge; the same applies hereinafter) for 6 hours. After charging, it was 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 3.0 at 0.2C
The battery was discharged to V to stabilize the non-aqueous electrolyte secondary battery. Furthermore, C up to 4.4V at 0.2C
After C-CV charging, the battery was discharged to 3.0 V at 0.2 C for initial conditioning.

[Charge storage test]
After the initial conditioning, the non-aqueous electrolyte secondary battery is again C at 0.2C to 4.4V.
After C-CV charging, high temperature storage was performed at 85 ° C. for 24 hours. After the non-aqueous electrolyte secondary battery was sufficiently cooled, it was immersed in an ethanol bath to measure the volume, and the amount of generated gas was obtained from the volume change before and after the storage test, and this was defined as the "charged storage gas amount". In Table 1 below, Comparative Example 1
The ratio of the charge storage gas amount when the charge storage gas amount of -1 is 100 is shown.

As is clear from Table 1, the non-aqueous electrolyte secondary battery produced in Example 1-1 is Comparative Example 1.
It can be seen that the amount of gas generated during high-temperature storage is reduced with respect to the non-aqueous electrolyte secondary batteries manufactured in -1 to 1-5.
That is, the non-aqueous electrolyte solution containing the specific phosphorus compound of the general formula (A) defined in the present invention has a larger amount of gas generated during high-temperature storage of the non-aqueous electrolyte solution secondary battery than the phosphorus compounds of the compounds 2 to 5. It can be seen that it can be significantly reduced.

<Examples 2-1 to 2-5, Comparative Examples 2-1 to 2-3>
[Preparation of positive electrode]
The same positive electrode as in Example 1-1 was produced.
[Manufacturing of negative electrode]
A negative electrode similar to that in Example 1-1 was produced.

[Preparation of non-aqueous electrolyte solution]
A non-aqueous electrolytic solution was prepared by adding the compounds shown in Table 2 below as additives to the reference electrolytic solution 1 prepared in Example 1-1. However, Comparative Example 2-1 is the reference electrolyte 1 itself. The "content (% by mass)" in the table is the content when the reference electrolytic solution 1 is 100% by mass.

[Manufacturing of non-aqueous electrolyte secondary batteries]
A laminated non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the above non-aqueous electrolyte was used.

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
The non-aqueous electrolyte secondary battery was constantly charged with a current corresponding to 0.05 C for 6 hours in a constant temperature bath at 25 ° 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. After that, 0.2C
The battery was discharged to 3.0 V to stabilize the non-aqueous electrolyte secondary battery. Furthermore, at 0.2C, 4.2
After CC-CV charging to V, the battery was discharged to 3.0 V at 0.2 C for initial conditioning.

[Charge storage test]
After the initial conditioning, use the non-aqueous electrolyte secondary battery again at 0.2C to 4.2V.
After C-CV charging, high temperature storage was performed at 85 ° C. for 24 hours. After the non-aqueous electrolyte secondary battery was sufficiently cooled, it was immersed in an ethanol bath to measure the volume, and the amount of generated gas was obtained from the volume change before and after the storage test, and this was defined as the "charged storage gas amount". In Table 2 below, Comparative Example 2
The ratio of the charge storage gas amount when the charge storage gas amount of -1 is 100 is shown.

As is clear from Table 2, the non-aqueous electrolyte secondary batteries produced in Examples 2-1 to 2-4 are
It can be seen that the amount of gas generated during high-temperature storage is reduced with respect to the non-aqueous electrolyte secondary batteries manufactured in Comparative Examples 2-1 to 2-2. Further, as the content of the specific phosphorus compound of the general formula (A) specified in the present invention increases, the gas suppressing effect is remarkably confirmed.
Further, by comparing Example 2-5 with Example 2-3 and Comparative Example 2-3, by using compound 1 and compound 6 which is a fluorinated salt in combination, the case of each compound alone is higher than that of the case of each compound alone. However, the amount of gas generated during high-temperature storage is further suppressed.

<Examples 3-1 to 3-4, Comparative Example 3-1>
[Preparation of positive electrode]
The same positive electrode as in Example 1-1 was produced.
[Manufacturing of negative electrode]
A negative electrode similar to that in Example 1-1 was produced.

[Preparation of non-aqueous electrolyte solution]
A non-aqueous electrolytic solution was prepared by adding the compounds shown in Table 3 below as additives to the reference electrolytic solution 1 prepared in Example 1-1. However, Comparative Example 3-1 is the reference electrolyte 1 itself. The "content (% by mass)" in the table is the content when the reference electrolytic solution 1 is 100% by mass.

[Manufacturing of non-aqueous electrolyte secondary batteries]
A laminated non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the above non-aqueous electrolyte was used.
<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
The initial conditioning of the non-aqueous electrolyte secondary battery was performed in the same manner as in Example 2-1.

[Charge storage test]
After the initial conditioning, use the non-aqueous electrolyte secondary battery again at 0.2C to 4.2V.
After C-CV charging, high temperature storage was performed under the conditions of 60 ° C. and 168 hours. After the non-aqueous electrolyte secondary battery was sufficiently cooled, it was immersed in an ethanol bath to measure the volume, and the amount of generated gas was obtained from the volume change before and after the storage test, and this was defined as the "charged storage gas amount". Table 3 below shows the ratio of the charge storage gas amount when the charge storage gas amount of Comparative Example 3-1 is 100.

Here, the charge storage test is performed by changing the high temperature storage conditions for the case of Example 2-1. As is clear from Table 3, the specific phosphorus of the general formula (A) specified in the present invention is performed. In the non-aqueous electrolyte solution containing the compound and the fluorinated salt, and the non-aqueous electrolyte solution containing the specific phosphorus compound of the general formula (C), the non-aqueous electrolyte solution 2 is the same as in the cases of Examples 2-1 to 5. It can be seen that the amount of gas generated during high-temperature storage of the next battery can be significantly reduced, and the effect of the present invention can be obtained regardless of the high-temperature storage conditions.

<Examples 4-1 to 4-2, Comparative Examples 4-1 to 4-2>
[Preparation of positive electrode]
Lithium cobalt oxide (LiCoO ₂ ) 97% by mass as the positive electrode active material, acetylene black 1.5% by mass as the conductive material, and polyvinylidene fluoride (PVdF) as the binder 1.
5% by mass was mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to obtain a positive electrode.

[Manufacturing of negative electrode]
A negative electrode similar to that in Example 1-1 was produced.
[Preparation of non-aqueous electrolyte solution]
A non-aqueous electrolytic solution was prepared by adding the compounds shown in Table 4 below as additives to the reference electrolytic solution 1 prepared in Example 1-1. However, Comparative Example 4-1 is the reference electrolyte 1 itself. The "content (% by mass)" in the table is the content when the reference electrolytic solution 1 is 100% by mass.

[Manufacturing of non-aqueous electrolyte secondary batteries]
A laminated non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the above non-aqueous electrolyte was used.
<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
The initial conditioning of the non-aqueous electrolyte secondary battery was performed in the same manner as in Example 2-1.

[Charge storage test]
A charge storage test was performed in the same manner as in Example 3-1. Table 4 below shows the ratio of the charge storage gas amount when the charge storage gas amount of Comparative Example 4-1 is 100.

Here, the non-aqueous electrolyte secondary battery is manufactured by changing the positive electrode active material as compared with the case of Example 3-1. As is clear from Table 4, the general formula specified in the present invention (as is clear from Table 4). The non-aqueous electrolyte solution containing the specific phosphorus compound of A) and the further fluorinated salt significantly increases the amount of gas generated during high-temperature storage of the non-aqueous electrolyte solution secondary battery as in the cases of Examples 3-1 and 2. It can be seen that the effect of the present invention can be obtained regardless of the material of the positive electrode.

<Examples 5-1 to 5-3, Comparative Examples 5-1 to 5-3>
[Preparation of positive electrode]
The same positive electrode as in Example 1-1 was produced.
[Manufacturing of negative electrode]
A negative electrode similar to that in Example 1-1 was produced.

[Preparation of non-aqueous electrolyte solution]
Ethylene carbonate (EC), ethyl methyl carbonate (in a dry argon atmosphere)
In a mixture of EMC) and diethyl carbonate (DEC) (volume volume ratio 3: 4: 3), 1.2 mol / L (concentration in the non-aqueous electrolyte solution) of fully dried LiPF ₆ was dissolved. (This is called the reference electrolyte 2). A non-aqueous electrolytic solution was prepared by adding the compounds shown in Table 5 below as additives to the reference electrolytic solution 2. However, Comparative Example 5-1 is the reference electrolyte 2 itself. The "content (% by mass)" in the table is the content when the reference electrolytic solution 2 is 100% by mass.

[Manufacturing of non-aqueous electrolyte secondary batteries]
A laminated non-aqueous electrolyte secondary battery was produced in the same manner as in Example 3-1 except that the above non-aqueous electrolyte was used.
<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
The initial conditioning of the non-aqueous electrolyte secondary battery was performed in the same manner as in Example 3-1.

[Charge storage test]
After the initial conditioning, use the non-aqueous electrolyte secondary battery again at 0.2C to 4.2V.
After C-CV charging, high temperature storage was performed under the conditions of 60 ° C. and 168 hours. After the non-aqueous electrolyte secondary battery was sufficiently cooled, it was immersed in an ethanol bath to measure the volume, and the amount of generated gas was obtained from the volume change before and after the storage test, and this was defined as the "charged storage gas amount". Example 5 in Table 5 below
The charge storage gas amounts of -1, 5-2 and 5-3 are Comparative Examples 5-1 and 5-2 and 5-, respectively.
The ratio of the charge storage gas amount when the charge storage gas amount of 2 is set to 100 is shown.

As is clear from Table 5, the non-aqueous electrolyte solution containing the specific phosphorus compound of the general formula (A) specified in the present invention is non-aqueous even when VC and FEC are not contained as additives, or even if any of them is contained. It can be seen that the amount of gas generated during high-temperature storage of the electrolytic solution secondary battery can be significantly reduced, and the effect of the present invention can be obtained.

According to the non-aqueous electrolyte solution of the present invention, the amount of gas generated during high-temperature storage of the non-aqueous electrolyte secondary battery can be improved, and it is useful as a non-aqueous electrolyte solution for a laminated battery.
Further, the non-aqueous electrolyte solution of the present invention and the non-aqueous electrolyte secondary battery using the non-aqueous electrolyte solution can be used for various known applications using the non-aqueous electrolyte secondary battery. As a specific example, for example,
Laptops, pen input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copies, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini discs, transceivers, electronic notebooks, calculators. , Memory card, portable tape recorder, radio, backup power supply, motor, bike, motorized bicycle, bicycle, lighting equipment, toys, game equipment, clock, power tool, strobe, camera, household backup power supply, office backup power supply,
Examples include a load leveling power source, a natural energy storage power source, and a lithium ion capacitor.

Claims (6)

Non-aqueous electrolyte solution A non-aqueous electrolyte solution for a secondary battery, wherein the non-aqueous electrolyte solution is at least one of the compounds represented by the following general formulas (A), (B) or (C) together with an electrolyte and a non-aqueous electrolyte solution. A non-aqueous electrolyte solution containing one type.

In the formulas (A), (B) and (C), R ¹ to R ³ independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 10 carbon atoms, and X is 6 to 10 carbon atoms . Shows 18 aryl groups.) The non-aqueous electrolyte solution further contains at least one additive selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a fluorinated salt and an oxalate salt. The non-aqueous electrolyte solution according to claim 1. The non-aqueous electrolyte solution according to claim 1 or 2 , wherein X is a phenyl group in the general formulas (A), (B) and (C). Claim 1 that the content of the compound represented by the general formula (A), (B) or (C) is 0.001% by mass or more and 10% by mass or less with respect to the total amount of the non-aqueous electrolytic solution. The non-aqueous electrolyte solution according to any one of 3 to 3 . The content of at least one compound selected from the group consisting of the cyclic carbonate having a carbon-carbon unsaturated bond, the cyclic carbonate having the fluorine atom, the fluorinated salt and the oxalate salt is the non-aqueous electrolysis. The non-aqueous electrolytic solution according to any one of claims 2 to 4 , which is 0.001% by mass or more and 10% by mass or less with respect to the total amount of the liquid. The non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of storing and releasing metal ions and a non-aqueous electrolytic solution, wherein the non-aqueous electrolytic solution is any one of claims 1 to 5 . A non-aqueous electrolyte secondary battery that is a non-aqueous electrolyte.