JP2019033074A - Nonaqueous electrolytic solution and secondary battery of the nonaqueous electrolytic solution - Google Patents

Abstract

To provide a nonaqueous electrolytic solution secondary battery in which a battery swelling at a repetition charging and discharging is small.SOLUTION: A nonaqueous electrolytic solution secondary battery comprising: a positive electrode and a negative electrode capable of adsorbing and discharging a metal ion; and a nonaqueous electrolytic solution, is a nonaqueous electrolytic solution secondary battery including at least one kind of chemical compounds expressed by following general expressions (A), (B), or (C) with an electrolytic solution and a nonaqueous solvent. (In the expressions (A), (B), and (C), each of Rto Rindependently expresses one to ten alkyl group of the number of hydrogen atom, fluorine atom or carbon, and X expresses the alkyl group of one to two of carbon or an aryl group of six to eighteen carbon.)SELECTED DRAWING: None

Description

The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery, and more specifically, a non-aqueous electrolyte containing a specific amount of a specific compound, and a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte. About.

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

For example, Patent Document 1 improves the cycle capacity retention rate at 25 ° C. by combining a negative electrode with a non-aqueous electrolyte containing a titanium and niobium-containing composite oxide and a specific phosphorus compound typified by triphenylphosphine oxide. Considerations are 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 electrolyte solution.

JP 2017-59393 A JP 2006-4746 A

In recent years, lithium secondary batteries, which are one type of non-aqueous electrolyte secondary batteries used for power supplies for electric vehicles and for mobile phones such as smartphones, have been accelerated and more In order to obtain a high 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, a gas typified by carbon dioxide or carbon monoxide is generated due to oxidative decomposition of the electrolyte solution at the positive electrode active material interface. However, the above-described high-capacity lithium secondary battery has a problem that the battery swells due to the generated gas because there are few voids in the case. For this reason, it is important to suppress the generation of gas during high-temperature storage.

However, according to the study by the present inventors, it has been found that the electrolyte 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 intensive studies to solve the above-mentioned problems, the present inventor has found that by using a non-aqueous electrolyte containing a phosphorus compound having a specific structure, it is possible to suitably suppress the generation of gas during high-temperature storage. Reached.
That is, the present invention provides specific embodiments shown in [1] to [7] below.
[1] Nonaqueous electrolyte solution for a nonaqueous electrolyte secondary battery, wherein the nonaqueous electrolyte solution is represented by the following general formula (A), (B) or (C) together with the electrolyte and the nonaqueous solvent A non-aqueous electrolyte containing at least one of the above.

(In the formulas (A), (B) and (C), R ^{1 to} R ³ each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 10 carbon atoms, and X represents an alkyl group having 1 to Represents an alkyl group of 10 or an aryl group having 6 to 18 carbon atoms.)
[2] The non-aqueous electrolyte further includes 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 nonaqueous electrolytic solution according to [1], which is contained.
[3] The nonaqueous electrolytic 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 as described in 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 electrolyte 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 a fluorine atom, the fluorinated salt, and the oxalate salt is 0.001% by mass with respect to the total amount of the non-aqueous electrolyte
The nonaqueous electrolytic solution according to any one of [2] to [5], which is 10% by mass or less.
[7] A non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting metal ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is any one of [1] to [6] A nonaqueous electrolyte secondary battery, which is the nonaqueous electrolyte solution 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 during high-temperature storage and obtain a non-aqueous electrolyte secondary battery with less battery swelling. It becomes.

Hereinafter, embodiments of the present invention will be described in detail. The following embodiments are examples (representative examples) of the embodiments of the present invention, and the present invention is not limited to these. In addition, the present invention can be implemented with any modifications without departing from the scope of the invention.

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

In formulas (A), (B), and (C), R ^{1 to} R ³ each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms, and X represents 1 to 10 carbon atoms. Or an aryl group having 6 to 18 carbon atoms.
Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, tert-butyl group, n-pentyl group, hexyl group, heptyl Group, octyl group, nonyl group, decyl group and the like. Among them, preferably a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, a hexyl group or a tert-butyl group, more preferably a methyl group, an ethyl group, an n-propyl group, an 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, 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 easily proceeds.

Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a tolyl group, a benzyl group, and a phenethyl group. Among these, a phenyl group or a tolyl group is preferable because concentration of the compound to the positive electrode active material easily proceeds.
In the general formulas (A) and (B), R ^{1 to} R ³ are each independently preferably a hydrogen atom or a methyl group. This is because the concentration of the compound into the positive electrode active material and the reaction activity are enhanced, and the active material surface 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 into the positive electrode active material and the reaction activity are enhanced, and the active material surface can be suitably modified.
As the compound contained in the nonaqueous electrolytic solution of the present invention, the compound represented by the general formula (A) is more preferable than 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 include compounds having the following structures.

Among them, preferred is a compound having the following structure. This is because an excessive decomposition reaction on the active material is suppressed.

More preferably, the compound of the following structures is mentioned. This is because the molecular size of the compound is suitable, and the concentration rate of the active material surface of the compound is increased.

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

Most preferably, the compound of the following structure is mentioned. This is because the reaction with the positive electrode active material proceeds more suitably, 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 (the total content when two or more types are included) is 0.001 mass. % Or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further 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, 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.

In addition, the compound represented by general formula (A), (B) or (C) may use a commercially available thing, and when manufacturing, the manufacturing method is not limited, It manufactures by a well-known method. Can be used.
If 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 is within the above range, the reforming reaction of the active material surface proceeds favorably and is stored at high temperature. It is possible to create a battery that generates less gas and is less likely to swell.

About the mechanism which can solve the subject of this invention by containing the compound of general formula (A), (B) or (C), it estimates as follows.
When a lithium secondary battery is placed in a high temperature environment, carbon dioxide and carbon monoxide are generated as a result of oxidative decomposition of the carbonate compound, which is a constituent of the electrolyte, at the positive electrode active material interface. To 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 formula (A), (B
The compound represented by (C) or (C) has a highly polar site (P = O) in the structure, so that it can be suitably converted into an active material by acting on the Lewis acid point of the transition metal oxide as the positive electrode active material. Can be adsorbed. In addition, since the compound represented by the general formula (A), (B) or (C) has an unsaturated bond having a high polymerization activity in the structure, it is adsorbed on the surface of the active material, and then oxidatively decomposes the electrolyte By reacting with the generated radical species, a composite film can be formed, and the active material surface can be suitably modified. Since this coating has insulating properties, it suppresses decomposition by oxidation reaction on the active material of lithium salt, solvent, and other additives that are constituents of the electrolyte, and contributes to suppression of gas generation during high-temperature storage. presume.

In addition, the method of making the non-aqueous electrolyte solution of this invention contain the compound represented by general formula (A), (B) or (C) in particular is not restrict | limited. In addition to the method of adding the above compound directly to the electrolyte,
The method of generating the said compound in a battery or electrolyte solution is mentioned.
In the present invention, the content of the compound represented by the general formula (A), (B) or (C) is the time when the non-aqueous electrolyte is manufactured, the time when the non-aqueous electrolyte is injected into the battery, or the battery is shipped as a battery It means the content at any given time.

In addition to the compound represented by the general formula (A), (B) or (C), the non-aqueous electrolyte of the present invention includes a cyclic carbonate having a carbon-carbon unsaturated bond described later, and a cyclic having a fluorine atom. The combined use of at least one compound selected from the group consisting of carbonates, fluorinated salts and oxalate salts is preferred in that a battery that is further prevented from generating gas during high-temperature storage and hardly swells 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 include 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 compound having carbon-carbon unsaturated bond>
Cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter, “unsaturated cyclic carbonate”)
As long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond, any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

Examples of unsaturated cyclic carbonates include vinylene carbonates; ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond; phenyl carbonates; vinyl carbonates; allyl carbonates; Catechol carbonates etc. are mentioned.
As vinylene carbonates, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-
Diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5- Examples thereof include phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene 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, 4-methyl-5- Vinyl ethylene carbonate, 4-allyl
5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-
5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene carbonate,
Phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-
Examples include 5-allylethylene carbonate.

Among these, preferable unsaturated cyclic carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl. Ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinyl Ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate or 4-vinyl-5 Include Ji nil ethylene carbonate.

Vinylene carbonate, vinyl ethylene carbonate or ethynyl ethylene carbonate is particularly preferred 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 effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily. The molecular weight of the unsaturated cyclic carbonate is more preferably 85
It is above, More preferably, it is 150 or less. The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.

An unsaturated cyclic carbonate may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Further, the blending amount of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired.
. 001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further 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, the non-aqueous electrolyte battery tends to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance ratio is reduced. Easy to avoid.

<1-3. Cyclic carbonate having a 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, for example, a fluorinated product of ethylene carbonate and a derivative thereof. Examples of the derivatives of fluorinated ethylene carbonate include fluorinated 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 derivatives thereof are preferred.

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 And carbonate.

Among them, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate provides high ion conductivity and suitably forms an interface protective film. And more preferable.
One cyclic carbonate compound having a fluorine atom may be used alone, or two or more cyclic carbonate compounds may be used in any combination and ratio.

The cyclic carbonate having a fluorine atom may be used alone or in combination of two or more in any combination and ratio. There is no restriction | limiting in the compounding quantity of the cyclic carbonate which has a fluorine atom with respect to the whole nonaqueous electrolyte solution of this invention, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually, with respect to the whole quantity of a nonaqueous electrolyte solution, it is 0.8. 001% by mass or more, preferably 0
. 01% by mass or more, more preferably 0.1% by mass or more, further 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.
Hereinafter, it is more preferably 5% by mass or less, and further 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 has a highly detachable fluorine atom in the structure. For example, the compound represented by the general formula (A) undergoes a reduction reaction to generate an anion ( A salt having a difluorophosphate salt, a fluorosulfonate salt, or a bisfluorosulfonylimide structure is preferable because it can react suitably with a nucleophile) to form a composite film. A difluorophosphate or a fluorosulfonate is more preferable because the elimination of fluorine atoms is particularly high and the reaction with a nucleophilic species preferably proceeds. Hereinafter, these various salts will be described.

<< Difluorophosphate >>
The counter cation of the difluorophosphate is not particularly limited, but lithium,
Sodium, potassium, rubidium, cesium, magnesium, calcium, barium,
And ammonium represented by NR ¹³ R ¹⁴ R ¹⁵ R ¹⁶ (wherein R ^{13 to} R ¹⁶ each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms). Can be mentioned.

Although there is no restriction | limiting in particular as a C1-C12 organic group represented by R < ¹³ > -R < ¹⁶ > in the said ammonium, For example, it is substituted by the alkyl group, the halogen atom, or the alkyl group which may be substituted by the halogen atom. Examples thereof include an cycloalkyl group which may be substituted, an aryl group which may be substituted with a halogen atom or an alkyl group, and a nitrogen atom-containing heterocyclic group which may have a substituent. Among them, it is preferable that R ^{13 to} R ¹⁶ are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group.

Specific examples of the difluorophosphate include lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate and the like, and among them, lithium difluorophosphate is preferable.
A difluorophosphate may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Further, the blending amount of the difluorophosphate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the blending amount of the difluorophosphate is usually based on the total amount of the nonaqueous electrolytic 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, Preferably it is 2 mass% or less, Most preferably, it is 1 mass% or less. If it is in this range, the swelling of the nonaqueous electrolyte battery accompanying charging / discharging can be suppressed suitably.

<< Fluorosulfonate >>
The counter cation of the fluorosulfonate is not particularly limited, but is the same as that of the difluorophosphate.
Specific examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, etc. Among them, lithium fluorosulfonate is preferable.

A fluorosulfonate may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Further, the blending amount of the fluorosulfonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. 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, most preferably 1% by mass.
It is as follows. If it is in this range, the swelling of the nonaqueous electrolyte battery accompanying charging / discharging can be suppressed suitably.

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

The 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% by mass with respect to the total amount of the nonaqueous electrolytic solution.
It is contained at a concentration of not less than mass%, usually not more than 10 mass%, preferably not more than 5 mass%, more preferably not more than 3 mass%. If it is in this range, the swelling of the nonaqueous electrolyte battery accompanying charging / discharging can be suppressed suitably.

<1-5. Oxalato 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 difluorooxalatoborate, lithium bis (oxalato) borate, lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate, and the like. Of these, lithium bis (oxalato) borate or lithium difluorobis (oxalato) phosphate is preferred.

One oxalate salt may be used alone, or two or more oxalate salts may be used in any combination and ratio. The amount of the oxalate salt is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The amount of the oxalate salt is usually 0.001 mass relative to the total amount of the nonaqueous electrolytic 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 is likely to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics are reduced, the amount of gas generation is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid the situation.

<1-6. Electrolyte>
The non-aqueous electrolyte solution of the present invention usually contains an arbitrary electrolyte other than the above materials, as in the case of a general non-aqueous electrolyte solution, 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 include the following.
For _{example, LiBF 4, LiClO 4, LiAlF} 4, LiSbF 6, LiTaF 6, L
Inorganic lithium salts such as iWF ₇ ; Lithium fluorophosphate salts such as LiPF ₆ ; LiWOF
Lithium tungstate salts 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 carboxylates 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 sulfonates 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
Lithium metide salts such as O ₂ ) ₃ ; lithium oxalates such as lithium difluorooxalatoborate, lithium bis (oxalato) borate, lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate Lato 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
_And fluorine-containing organic lithium salts such as ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ .

In addition to the gas suppression effect during high-temperature storage obtained by the present invention, from the point of further enhancing the effect of improving the charge / discharge rate charge / discharge characteristics and impedance characteristics, inorganic lithium salts, lithium fluorophosphate salts, lithium sulfonate salts, lithium imide Those selected from salts and lithium oxalate salts are preferred.
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 difluorooxalatoborate, lithium bis (oxalato) borate, lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate or lithium Tris (oxalato) 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. Moreover, the said lithium salt may be used independently, or may use 2 or more types together.

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 with respect to the total amount of the non-aqueous electrolyte solution. % Or more. Moreover, the upper limit is 18 mass% or less normally, Preferably it is 17 mass% or less, More preferably, it is 16 mass% or less. When the total concentration of the electrolyte is within the above range, the electric conductivity is appropriate for battery operation, and thus sufficient output characteristics tend to be obtained.

<1-7. Nonaqueous solvent>
The non-aqueous electrolyte solution of the present invention usually contains a non-aqueous solvent that dissolves the above-described electrolyte as a main component, as with a general non-aqueous electrolyte solution. There is no restriction | limiting in particular about the nonaqueous solvent used here, A well-known organic solvent can be used. Examples of organic solvents include, but are not limited to, saturated cyclic carbonates, chain carbonates, ether compounds, sulfone compounds, and the like. These can be used alone or in combination of two or more.

<< 1-7-1. Saturated cyclic carbonate >>
Examples of the saturated cyclic carbonate usually 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 derived 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. Among these, ethylene carbonate and propylene carbonate are preferable, and ethylene carbonate that is difficult to be oxidized and reduced is more preferable. A saturated cyclic carbonate may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.

The content of the saturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the lower limit of the content when one type is used alone is based on the total amount of the solvent of the nonaqueous electrolytic solution. In general, it is 3% by volume or more, preferably 5% by volume or more. By setting this range,
A decrease in electrical conductivity resulting from a decrease in the dielectric constant of the non-aqueous electrolyte solution is avoided, and the high-current discharge characteristics, stability to the negative electrode, and cycle characteristics of the non-aqueous electrolyte secondary battery are easily in a favorable range.
Moreover, an upper limit is 90 volume% or less normally, Preferably it is 85 volume% or less, More preferably, it is 80 volume% or less. By setting it within this range, the oxidation / reduction resistance of the nonaqueous electrolytic solution is improved, and the stability during high-temperature storage tends to be improved.
In addition, the volume% in this invention means the value in the volume in 25 degreeC and 1 atmosphere.

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

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate or methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate is particularly preferable. is there.
Also, chain carbonates having fluorine atoms (hereinafter referred to as “fluorinated chain carbonate”)
May be abbreviated. ) Can also be suitably 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 may be bonded to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

Fluorinated dimethyl carbonate derivatives include fluoromethyl methyl carbonate,
Difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (
Fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate and the like.
Fluorinated ethyl methyl carbonate derivatives include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2-trimethyl Examples include fluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, and ethyl trifluoromethyl carbonate.

Fluorinated diethyl carbonate derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, 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- 2 ', 2'-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, etc. are mentioned.

A chain carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a 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,
Usually, it is 15 volume% or more, preferably 20 volume% or more, more preferably 25 volume% or more. Moreover, it is 90 volume% or less normally, Preferably it is 85 volume% or less, More preferably, it is 80 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 to an appropriate range, the decrease in ionic conductivity is suppressed, and the output characteristics of the non-aqueous electrolyte secondary battery are thus in a good range. And it will be easier.

Furthermore, battery performance can be remarkably improved by combining ethylene carbonate with a specific content with respect to a specific chain carbonate.
For example, when dimethyl carbonate and ethyl methyl carbonate are selected as specific chain carbonates, the content of ethylene carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. 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, based on the total amount of the solvent. The volume is 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%.
It is at least 50% by volume and usually at most 50% by volume, preferably at most 45% by volume. By setting the content within the above range, the 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, 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-propylether , (N-propyl) (3-fluoro-n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2
, 3,3-tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3,
3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl)
Ether, (3-fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-
Propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2 , 3
, 3,3-pentafluoro-n-propyl) ether, di (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (
2,2,3,3,3-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-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 include di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 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 has a high solvating ability to lithium ions and has an ion dissociation property. 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 effects of the present invention are not significantly impaired. However, in 100% by volume of the nonaqueous solvent, usually 1% by volume or more, preferably 2% by volume or more,
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 volume% or less. If the content of the ether compound is within the above preferred range, it is easy to ensure the effect of improving the ionic conductivity resulting from the improvement of the lithium ion dissociation degree and the viscosity reduction of the chain ether. In addition, when the negative electrode active material is a carbonaceous material, the phenomenon that the chain ether is co-inserted with the lithium ions can be suppressed, so that the input / output characteristics and the charge / discharge rate characteristics can be within an appropriate range.

<1-7-4. Sulfone compounds>
The sulfone compound is not particularly limited as long as it is a cyclic sulfone or a chain sulfone. However, in the case of a cyclic sulfone, the sulfone compound usually has 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms. In the case of, a compound having usually 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms is preferred. 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 that are monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones that are disulfone compounds. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

As sulfolanes, sulfolane and / or sulfolane derivatives are preferred. As the sulfolane derivative, one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.
Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3
-Fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2- Fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-
Fluoro-3-methyl sulfolane, 4-fluoro-2-methyl sulfolane, 5-fluoro-3-methyl sulfolane, 5-fluoro-2-methyl sulfolane, 2-fluoromethyl sulfolane, 3-fluoromethyl sulfolane, 2-difluoromethyl Sulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3
-(Trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane or 5-fluoro-3- (trifluoromethyl) sulfolane is preferred because of high ionic conductivity and high input / output.

As the chain sulfone, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n- Butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, Trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trif Oromethylsulfone, perfluoroethylmethylsulfone, ethyltrifluoroethylsulfone, ethylpentafluoroethylsulfone, di (trifluoroethyl) sulfone, perfluorodiethylsulfone, fluoromethyl-n-propylsulfone, difluoromethyl-n-propylsulfone , Trifluoromethyl-n-
Propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, 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.

Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, tri Ruoroechiru -n- butyl sulfone, trifluoroethyl -t- butyl sulfone, trifluoromethyl -n- butyl sulfone or trifluoromethyl -t- butyl sulfone is preferable in terms of improving the high-temperature storage stability of the electrolytic solution.

The content of the sulfone compound is not particularly limited and may be arbitrary as long as the effects of the present invention are not significantly impaired.
. It is 5% by volume or more, more preferably 1% by volume or more, and is 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 excellent in high-temperature storage stability tends to be obtained.

<1-8. Auxiliary>
The non-aqueous electrolyte solution of the present invention may contain auxiliary agents such as a compound having a cyano group, a diisocyanate compound, a carboxylic acid anhydride, and an overcharge inhibitor within the range where the effects of the present invention are exhibited.

<< 1-8-1. Compound having cyano group >>
In the non-aqueous electrolyte solution of the present invention, 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 production method of the compound having a cyano group is not particularly limited, and can be produced by arbitrarily selecting a known method.

In 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. And a V-valent organic group having 1 to 10 carbon atoms. V is an integer greater than or equal to 1, and V
When T 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.
Below, more preferably 170 or less. If it is this range, it will be easy to ensure the solubility of the compound which has a cyano group with respect to nonaqueous electrolyte solution, and the effect of this invention will be easy to be expressed.

Specific examples of the compound represented by the general formula (1) include, for example, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile 2-methylbutyronitrile, trimethylacetonitrile, Hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitryl, 2-pentenenitrile, 2-methyl-2- Pentenenitrile, 3
-Methyl-2-pentenenitrile, 2-hexenenitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 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 ′ -Compounds having one cyano group such as thiodipropionitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, pentafluoropropionitrile;

Malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, 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) amine;

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, ethanesulfonyl cyanide, propanesulfonyl cyanide, butanesulfonyl cyanide, pentanesulfonyl cyanide, hexanesulfonyl cyanide , Heptanesulfonyl cyanide, methylsulfurocyanidate, ethylsulfurocyanidate, propylsulfurocyanidate, butylsulfurocyanidate, pentylsulfurocyanidate, hexylsulfurocyanidate, heptylsulfur Sulfur-containing compounds such as frocyanidates;

Cyanodimethylphosphine, cyanodimethylphosphine oxide, methyl cyanomethylphosphinate, methyl cyanomethylphosphinate, dimethylphosphinic acid cyanide, dimethylphosphinic acid cyanide, dimethylphosphonic acid dimethyl, cyanophosphonic acid dimethyl, methylphosphonic acid cyanomethyl, methylphosphonic acid Phosphorus-containing compounds such as cyanomethyl acid, cyanodimethyl phosphate, and cyanodimethyl phosphite;
Is mentioned.

Of these, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, crotononitrile, 3-
Methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile or dodecandinitrile are preferred from the standpoint of improving storage properties, and malononitrile, succinonitrile, glutaronitrile Adiponitrile, pimelonitrile, suberonitrile, azeronitrile, sebacononitrile, undecanedinitrile or dodecanedinitrile are more preferred.

The compound which has a cyano group may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios. There is no limitation on the content of the compound having a cyano group with respect to the entire non-aqueous electrolyte solution of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. 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 1
It is contained at a concentration of 0% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. When the above range is satisfied, effects such as low-temperature output characteristics, charge / discharge rate characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

<1-8-2. Diisocyanate Compound>
In the non-aqueous electrolyte 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. The compound represented by (2) is preferred.

In the above general formula (2), Y is an organic group having a cyclic structure and having 1 to 15 carbon atoms. The carbon number of Y is usually 2 or more, preferably 3 or more, more preferably 4 or more,
It is usually 14 or less, preferably 12 or less, more preferably 10 or less, and still more preferably 8
It is as follows.
In the above general formula (2), Y is particularly preferably an organic group having 4 to 15 carbon atoms having one or more cycloalkylene groups or aromatic hydrocarbon groups having 4 to 6 carbon atoms. 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 the cyclic structure is sterically bulky and is a molecule, side reaction on the positive electrode hardly occurs, and as a result, cycle characteristics and 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, the para position, and the ortho position. An appropriate inter-crosslinking distance is advantageous for lithium ion conductivity and is preferable because resistance can be easily lowered. In addition, the cycloalkylene group is preferably a cyclopentylene group or a cyclohexylene group from the viewpoint that the diisocyanate compound itself hardly causes side reactions, and the cyclohexylene group is resistant to the influence of molecular mobility. It is more preferable because it is easily lowered.

Moreover, it is preferable to have a C1-C3 alkylene group between a cycloalkylene group or an aromatic hydrocarbon group, and an isocyanate group. By having an alkylene group, it becomes sterically bulky, so that side reactions on the positive electrode are less likely to occur. Furthermore, if the alkylene group has 1 to 3 carbon atoms, the ratio of the isocyanate group to the total molecular weight does not change greatly, and thus the effect of the present invention is remarkably easily 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 effects of the present invention are 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. If it is this range, it will be easy to ensure the solubility of the diisocyanate compound with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed.

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, dicyclohexylmethane-2,4′-diisocyanate, dicyclohexylmethane-3,3′-
Cycloalkane ring-containing diisocyanates such as diisocyanate and dicyclohexylmethane-4,4′-diisocyanate;

1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate, 1,4
-Phenylene diisocyanate, tolylene-2,3-diisocyanate, tolylene-2,
4-diisocyanate, tolylene-2,5-diisocyanate, tolylene-2,6-diisocyanate, tolylene-3,4-diisocyanate, tolylene-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 such as natonaphthalene, 2,3-diisocyanatonaphthalene, 1,5-bis (isocyanatomethyl) naphthalene, 1,8-bis (isocyanatomethyl) naphthalene, 2,3-bis (isocyanatomethyl) naphthalene Ring-containing diisocyanates;
Is 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-phenylene diisocyanate, 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 preferable because a denser composite film is formed on the negative electrode, and as a result, battery durability is improved.

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

The diisocyanate compound mentioned above may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
In the non-aqueous electrolyte solution of the present invention, the content of the diisocyanate compound that can be used is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. In general, 0.001% by mass or more, preferably 0.01% by mass or more,
More preferably, it is 0.1 mass% or more, More preferably, it is 0.3 mass% or more, Usually, 5 mass% or less, Preferably it is 4 mass% or less, More preferably, it is 3 mass% or less, More preferably, 2
It is below mass%. When the content is within the above range, battery characteristics such as low temperature output and cycle characteristics tend to be further improved.
In addition, the manufacturing method in particular of a diisocyanate compound is not restrict | limited, A well-known method can be selected arbitrarily and can be manufactured. Moreover, you may use a commercial item.

<1-8-3. Other auxiliaries>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. Examples of other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; methyl-2-propynyl oxalate, ethyl-2-propynyl oxalate, bis (2 -Propynyl) oxalate,
2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, di (2-propynyl) glutarate, methyl-2-propynyl carbonate, ethyl-
2-propynyl carbonate, bis (2-propynyl) carbonate, 2-butyne-1,
4-diyl-dimethanesulfonate, 2-butyne-1,4-diyl-diethanesulfonate, 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
-Propynyl-methanesulfonate, 1,1-dimethyl-2-propynyl-methanesulfonate, 2-propynyl-ethanesulfonate, 2-propynyl-vinylsulfonate,
2-propynyl-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 sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, ethylene sulfate, vinylene sulfate, diphenylsulfone, N, N -Sulfur-containing compounds such as dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, trimethylsilyl methyl sulfate, trimethylsilyl ethyl sulfate, 2-propynyl-trimethylsilyl sulfate; 2-isocyanatoethyl acrylate, 2-
Isocyanatoethyl methacrylate, 2-isocyanatoethylcrotonate, 2- (2-
Isocyanato 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, pentafluorophenyl methanesulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate,
Fluorinated aromatic compounds such as pentafluorophenyl trifluoroacetate and methylpentafluorophenyl carbonate; tris (trimethylsilyl) borate, tris (trimethoxysilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethoxysilyl) phosphate ), Dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titanium tetrakis (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 and 2-ethyl methanesulfonyloxyacetate; lithium ethylmethyloxycarbonylphosphonate, lithium ethylethyloxycarbonylphosphonate,
Lithium ethyl-2-propynyloxycarbonylphosphonate, lithium ethyl-1-
And lithium salts such as methyl-2-propynyloxycarbonylphosphonate and lithium ethyl-1,1-dimethyl-2-propynyloxycarbonylphosphonate. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity maintenance 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 other auxiliaries is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, based on the total amount of the non-aqueous electrolyte solution. Usually, it is 5 mass% or less, Preferably it is 3 mass% or less, More preferably, it is 1 mass% or less. Within this range, the effects of other auxiliaries can be sufficiently exhibited and the high-temperature storage stability tends to be improved.

<2. Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery of the present invention includes a current collector and a positive electrode having a positive electrode active material layer provided on the current collector, and a current collector and a negative electrode active material provided on the current collector. A negative electrode having a layer and capable of occluding and releasing ions and the non-aqueous electrolyte solution of the present invention described above are provided.

<2-1. Battery configuration>
The non-aqueous electrolyte secondary battery of the present invention is the same as the conventionally known non-aqueous electrolyte secondary battery except for the above-described non-aqueous electrolyte solution of the present invention. Usually, a positive electrode and a negative electrode are laminated through a porous film (separator) impregnated with the non-aqueous electrolyte solution of the present invention, and these are case (
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 shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<2-2. Non-aqueous electrolyte>
As the non-aqueous electrolyte, the above-described non-aqueous electrolyte of the present invention is used. In addition, in the range which does not deviate from the meaning of this invention, it is also possible to mix | blend and use other nonaqueous electrolyte solutions with respect to the nonaqueous electrolyte solution of this invention.

<2-3. Negative electrode>
The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release metal ions. Specific examples include those having carbon as a constituent element such as a carbonaceous material, alloy materials, and the like. These are 1
You may use a seed | species independently and may use it combining 2 or more types arbitrarily.

<< 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, (4
) Carbon-coated graphite, (5) graphite-coated graphite, and (6) resin-coated graphite.

(1) Examples of natural graphite include scaly graphite, scaly graphite, soil graphite, and / or graphite particles obtained by subjecting these graphites as raw materials to spheroidization and densification. Among these, spherical or ellipsoidal graphite subjected to spheroidizing treatment is particularly preferable from the viewpoints of particle filling properties and charge / discharge rate characteristics.
As an apparatus used for the spheronization treatment, for example, an apparatus that repeatedly gives mechanical action such as compression, friction, shearing force, etc. 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 the rotor rotates at high speed, so that impact compression, friction, and shear force are applied to the raw material of natural graphite (1) introduced inside. A device that applies a mechanical action such as spheroidization is preferable. Also,
An apparatus having a mechanism for repeatedly applying a mechanical action by circulating the raw material is preferable.

For example, when the spheroidizing process is performed using the above-described apparatus, the peripheral speed of the rotating rotor is set to 30 to 30.
It is preferably set to 100 m / sec, more preferably set to 40 to 100 m / sec, and further preferably set to 50 to 100 m / sec. Further, the spheronization treatment can be performed by simply passing the raw material, but it is preferable to circulate or stay in the apparatus for 30 seconds or more, and to circulate or stay in the apparatus for 1 minute or more. Is more preferable.

(2) Artificial graphite includes coal tar pitch, coal heavy oil, atmospheric residue, petroleum heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, Organic compounds such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymer, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, imide resin are usually 25
Graphitized at a temperature in the range of 00 ° C. or higher and usually 3200 ° C. or lower, and pulverized and / or classified as necessary.

At this time, a silicon-containing compound, a boron-containing compound, or the like can be used as a graphitization catalyst. In addition, artificial graphite obtained by graphitizing mesocarbon microbeads separated in the heat treatment process of pitch can be mentioned. Furthermore, the artificial graphite of the granulated particle which consists of primary particles is also mentioned. For example, mesocarbon microbeads, graphitizable carbonaceous material powder such as coke and tar,
A plurality of flat particles obtained by mixing a graphitizable binder such as pitch and a graphitization catalyst, graphitizing, and pulverizing as necessary, are assembled or bonded so that the orientation planes are non-parallel. Examples include graphite particles.

(3) As 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 (400 to 2200 ° C.) that is not graphitized, and amorphous carbon particles that have been heat-treated using a non-graphitizable carbon precursor such as a resin as a raw material. It is done.

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

(5) Examples of the graphite-coated graphite include those obtained as follows. Natural graphite and / or artificial graphite and a carbon precursor of an easily graphitizable organic compound such as tar, pitch or resin are mixed and heat-treated at least in the range of about 2400 to 3200 ° C. The obtained natural graphite and / or artificial graphite is used as nuclear graphite, and the whole or part of the surface of the nuclear graphite is coated with a graphitized product to obtain graphite-coated graphite (5).

(6) The resin-coated graphite is obtained by mixing natural graphite and / or artificial graphite with a resin or the like, for example, 4
It can be obtained by using natural graphite and / or artificial graphite obtained by drying at a temperature lower than 00 ° C. as core graphite and coating the core graphite with a resin or the like.
Moreover, the carbonaceous material of (1)-(6) demonstrated above may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Examples of organic compounds such as tar, pitch and resin used in the carbonaceous materials (2) to (5) above include heavy coal oil, heavy DC oil, heavy petroleum oil, and aromatic hydrocarbons. , N ring compounds, S ring compounds, polyphenylene, organic synthetic polymers, natural polymers, organic compounds capable of carbonization selected from the group consisting of thermoplastic resins and thermosetting resins. The raw material organic compound may be used after being dissolved in a low molecular organic solvent in order to adjust the viscosity at the time of mixing.

Moreover, as natural graphite and / or artificial graphite used as a raw material of nuclear graphite, natural graphite subjected to spheroidizing treatment is preferable.
Next, the alloy material used as the negative electrode active material is lithium simple substance, single metal and alloy forming lithium alloy, or oxides thereof, as long as it can occlude and release lithium.
Any of carbides, nitrides, silicides, sulfides, phosphides and the like may be used, and there is no particular limitation. The single metal and the 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, silicon and tin simple metals and alloys or compounds containing these atoms,
It has silicon or tin as a constituent element. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

<<< Metal particles that can be alloyed with Li >>>
When a single metal and an alloy forming a lithium alloy, or a compound thereof, such as an oxide, carbide, nitride, silicide, sulfide or phosphide, is used as the negative electrode active material, the metal that can be alloyed with Li is: It is in particle form. As a method for confirming that the metal particles are metal particles that can be alloyed with Li, identification of the metal particle phase by X-ray diffraction, observation of the particle structure by electron microscope and elemental analysis, element by fluorescent X-rays Analysis and the like.

As the metal particles that can be alloyed with Li, any conventionally known metal particles can be used,
In terms of capacity and cycle life of the non-aqueous electrolyte secondary battery, the metal particles are, 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 of 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, and metal carbides. Moreover, you may use the alloy which consists of 2 or more types of metals.
Among metal particles that can be alloyed with Li, Si or Si metal compounds are preferable. The Si metal compound is preferably a Si metal oxide. Si or 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 S
The i metal oxide is SiOx in general formula. This general formula SiOx represents Si dioxide (
SiO2) and metal Si (Si) are obtained as raw materials, and the value of x is usually 0 ≦ x <2.
It is. SiOx has a larger theoretical capacity than graphite. Furthermore, amorphous Si or nano-sized Si crystals easily allow alkali ions such as lithium ions to enter and exit, so that a high capacity can be obtained.

The Si metal oxide is specifically expressed as SiOx, and x is 0 ≦ x <2, more preferably 0.2 or more and 1.8 or less, and still more preferably 0.4. 1.6 or less,
Particularly preferably, it is 0.6 or more and 1,4 or less. If it is this range, it becomes possible to reduce the irreversible capacity | capacitance by the coupling | bonding of Li and oxygen simultaneously with a battery having a high capacity | capacitance.
-Average particle diameter of metal particles that can be alloyed with Li (d50)
The average particle diameter (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 nonaqueous electrolyte secondary battery. More preferably, it is 0.3 μm or more, usually 10 μm or less, preferably 9 μm or less, more preferably 8 μm or less. When the average particle diameter (d50) is within the above range, volume expansion associated with discharge of the rechargeable battery is reduced, and good cycle characteristics can be obtained while maintaining the charge / discharge capacity.
The average particle diameter (d50) is determined by a laser diffraction / scattering particle size distribution measuring method or the like.

BET specific surface area of metal particles that can be alloyed with Li The specific surface area determined by the BET method of metal particles that can be alloyed with Li is usually 0.5 to 60 m.
2 / g, preferably 1 to 40 m <2> / g. When the specific surface area by the BET method of the metal particles that can be alloyed with Li is within the above range, the charge / discharge efficiency and discharge capacity of the battery are high,
Lithium is quickly taken in and out at high speed charge and discharge, and is excellent in rate characteristics.

-The amount of oxygen contained in the metal particles that can be alloyed with Li The amount of oxygen contained in the 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 preferred. The oxygen distribution state in the particles may be present near the surface, present inside the particle, or uniformly present within the particle, but is preferably present near the surface. When the oxygen content of the metal particles that can be alloyed with Li is within the above range, the volume expansion associated with the secondary charge / discharge of the nonaqueous electrolyte solution is suppressed due to the strong bond between the metal particles and O, and the cycle characteristics are excellent. preferable.

<<< Negative Electrode Active Material Containing Li and Alloyable Metal Particles and Graphite Particles >>>
The negative electrode active material may contain metal particles that can be alloyed with Li and graphite particles. The negative electrode active material may be a mixture in which metal particles capable of being alloyed with Li and graphite particles are mixed in a state of independent particles, or metal particles capable of being alloyed with Li are formed on the surface of the graphite particles and It may also be a complex present inside.

The composite of metal particles that can be alloyed with Li and graphite particles (also referred to as composite particles) is particularly limited as long as the particles include metal particles that can be alloyed with Li and graphite particles. However, it is preferably a particle in which metal particles capable of being alloyed with Li and graphite particles are integrated by physical and / or chemical bonding. As a more preferable form, the solid particles are dispersed in the particles so that the metal particles and graphite particles that can be alloyed with Li are present at least on the surface of the composite particles and in the bulk. They are physically and / or
Alternatively, the graphite particles are present in order to be integrated by chemical bonding. More specifically, a preferable form is a composite material composed of at least metal particles capable of being alloyed with Li and graphite particles, and the graphite particles, preferably, natural graphite has a folded structure with a curved structure. In addition, the composite material (negative electrode active material) is characterized in that metal particles capable of being alloyed with Li are present in the gaps in the structure. The gap may be a gap, or a substance that buffers expansion and contraction of metal particles that can be alloyed with Li, such as amorphous carbon, graphite, and resin, is present in the gap. May be.

-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 sum of metal particles that can be alloyed with Li and graphite particles is usually 0.1% by mass or more, preferably 0 .5 mass% or more, more preferably 1
. It is 0 mass% or more, More preferably, it is 2.0 mass% or more. Moreover, usually 99 mass% or less,
Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass%
Hereinafter, 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. In this range, S
It is preferable in that the side reaction on the i surface can be controlled, and a sufficient capacity can be obtained in the non-aqueous electrolyte secondary battery.

(Coverage)
The negative electrode active material of the present invention may be coated with a carbonaceous material or a graphite material. Of these, coating with an amorphous carbonaceous material is preferable from the viewpoint of lithium ion acceptability. 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. When 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 be small. If the coverage is too small, the core carbonaceous material is not evenly coated with amorphous carbon and strong granulation is not performed, and when pulverized after firing, the particle size tends to be too small.

In addition, the coverage (content rate) of the carbide | carbonized_material derived from the organic compound of the negative electrode active material finally obtained is
The amount of the negative electrode active material, the amount of the organic compound, and the residual carbon ratio measured by a micro method based on JIS K 2270 can be calculated by the following formula.
Formula: coverage of carbide derived from organic compound (%) = (mass of organic compound × residual carbon ratio × 100)
/ {Mass of negative electrode active material + (mass of organic compound x residual carbon ratio)}

(Internal porosity)
The internal porosity of the negative electrode active material is usually 1% or more, preferably 3% or more, more preferably 5% or more, and further preferably 7% or more. Further, it is usually less than 50%, preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. If the internal porosity is too small, the amount of liquid in the particles of the negative electrode active material in the non-aqueous electrolyte secondary battery decreases, and the charge / discharge characteristics tend to deteriorate. On the other hand, when the internal porosity is too large, the interparticle gap is small when the electrode is used, and the nonaqueous electrolyte solution tends to be insufficiently diffused. In addition, in this void, a substance that buffers expansion and contraction of metal particles that can be alloyed with Li, such as amorphous carbon, graphite, and resin, is present in the void or filled with the void. May be.

<Configuration and production method of negative electrode>
Any known method can be used for the production of the negative electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to the negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

Further, the alloy-based material negative electrode can be produced by any known method.
Specifically, as a manufacturing method of the negative electrode, for example, a method in which a negative electrode active material added with a binder or a conductive material is roll-formed as it is to form a sheet electrode, or a compression-molded pellet electrode and The above negative electrode is usually applied to a negative electrode current collector (hereinafter also referred to as “negative electrode current collector”) by a method such as a coating method, a vapor deposition method, a sputtering method, or a plating method. A method of forming a thin film layer (negative electrode active material layer) containing an active material is used. In this case, by adding a binder, a thickener, a conductive material, a solvent, etc. to the above-mentioned negative electrode active material to form a slurry, applying this to the negative electrode current collector, drying, and pressing to increase the density A negative electrode active material layer is formed on the negative electrode current collector.

Examples of the material for the negative electrode current collector include steel, copper, copper alloys, nickel, nickel alloys, and stainless steel. Of these, copper foil is preferred 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 be difficult.

In addition, in order to improve the binding effect with the negative electrode active material layer formed on the surface, the surface of these negative electrode current collectors is preferably subjected to a roughening treatment in advance. Surface roughening methods include blasting, rolling with a rough roll, abrasive cloth paper with abrasive particles fixed, grindstone, emery buff,
Examples thereof include a mechanical polishing method, an electrolytic polishing method, a chemical polishing method, and the like that polish the surface of the current collector with a wire brush 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 negative electrode current collector such as an expanded metal or a punching metal can be used. This type of negative electrode current collector can be freely changed in mass by changing its aperture ratio. Further, when a negative electrode active material layer is formed on both surfaces of this type of negative electrode current collector, the negative electrode active material layer is further less likely to peel due to the rivet effect through the hole. 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, and thus the adhesive strength may be lowered.

The slurry for forming the negative electrode active material layer is usually prepared by adding a binder, a thickener and the like to the negative electrode material. In addition, the “negative electrode material” in this specification refers to a material in which a negative electrode active material and a conductive material are combined.
The content of the negative electrode active material in the negative electrode material is usually 70% by mass or more, particularly 75% by mass or more,
Further, it is usually 97% by mass or less, particularly preferably 95% by mass or less. When 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. When the content is too large, the content of the conductive material is relatively insufficient, so that It tends to be difficult to ensure conductivity. When two or more negative electrode active materials are used in combination, the total amount of the negative electrode active materials may be set to 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. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. In particular, it is preferable to use a carbon material as the conductive material because the carbon material acts as an active material. The content of the conductive material in the negative electrode material is usually 3
% By 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 small, the conductivity tends to be insufficient.
If the amount is too large, the battery capacity and strength tend to decrease due to the relative shortage of the negative electrode active material content. Note that 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 safe with respect to the solvent and the electrolytic solution used at the time of producing the electrode. Examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene / acrylic acid copolymer, and ethylene / methacrylic acid copolymer. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a 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 preferable that it is below mass parts. When the content of the binder is too small, the strength of the obtained negative electrode tends to be insufficient, and when the content is too large, the content of the negative electrode active material and the like is relatively insufficient.
Battery capacity and conductivity tend to be insufficient. In addition, when using two or more binders together, what is necessary is just to make it the total amount of a binder satisfy | fill the said range.

As the thickener used for the negative electrode, carboxymethylcellulose, methylcellulose,
Examples thereof include hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein. One of these may be used alone, or 2
You may use a seed or more together by arbitrary combinations and ratios. The thickener may be used as necessary, but when used, the content of the thickener in the negative electrode active material layer is usually 0.5% by mass.
It is preferably used in the range of 5% by mass or less.

The slurry for forming the negative electrode active material layer is prepared by mixing a conductive material, a binder, and a thickener as necessary with the negative electrode active material, and using an aqueous solvent or an organic solvent as a dispersion medium. The As the aqueous solvent, water is usually used, and an organic solvent such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone is used in combination within a range of 30% by mass or less with respect to water. 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,
Aromatic hydrocarbons such as anisole, toluene and xylene, and alcohols such as butanol and cyclohexanol, among others, cyclic amides such as N-methylpyrrolidone, N,
Linear amides such as N-dimethylformamide and N, N-dimethylacetamide are preferred. Any one of these may be used alone, or two or more may be used in any combination and ratio.

The obtained slurry is applied onto the above-described negative electrode current collector, dried, and then pressed to form a negative electrode active material layer, thereby obtaining a negative electrode. 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 a known method such as natural drying, heat drying, or reduced pressure drying can be used.

(Electrode density)
The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g · cm −3 or more, and 1.2 g · cm −3 or more. Is more preferably 1.3 g · cm −3 or more, preferably 2.2 g · cm −3 or less, more preferably 2.1 g · cm −3 or less, and 2.0 g · cm −3 or less. Further preferred is 1.9 g · cm −3 or less. When the density of the negative electrode active material present on the current collector exceeds the above range, the negative electrode active material particles are destroyed, and the initial irreversible capacity of the non-aqueous electrolyte secondary battery is increased, or the current collector / negative electrode There is a case where high current density charge / discharge characteristics are deteriorated due to a decrease in permeability of the non-aqueous electrolyte solution near the active material interface. On the other hand, if the amount is less than the above range, the conductivity between the negative electrode active materials decreases, the battery resistance increases, and the capacity per unit volume may decrease.

<2-4. Positive electrode>
The positive electrode used for the non-aqueous electrolyte secondary battery of the present invention will be described below.
<< 2-4-1. Cathode 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 lithium cobaltate, transition metal oxides containing at least Ni and Co, and 50 mol% or more of transition metals being Ni and Co. There is no particular limitation as long as it can occlude and release metal ions, but those that can occlude and release lithium ions electrochemically are preferable, and contain lithium, at least Ni and Co, and 50 mol of transition metal. More preferred are transition metal oxides in which at least% is Ni and Co. Ni
This is because Co and Co are suitable for use as a positive electrode material of a secondary battery, and are suitable for high capacity applications.

The transition metal component of the lithium transition metal oxide includes Ni and Co as essential elements, but other metals include Mn, V, Ti, Cr, Fe, Cu, Al, Mg, Zr, and E.
r etc. are mentioned, Mn, Ti, Fe, Al, Mg, Zr etc. 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 O 2, 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 etc. are mentioned.

Among these, a transition metal oxide represented by the following composition formula (4) is preferable.
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, the transition metal is difficult to elute from the positive electrode, and even if it elutes, Ni and Co are not contained in the non-aqueous secondary battery. This is because the adverse effect of is small.
Among these, a transition metal oxide represented by the following composition formula (5) is more preferable.
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 value of 0.0 ≦ d2 ≦ 0.5 is shown, c2 ≦ b2 and 0.6 ≦ b2 + c2 and b2 + c2
+ D2 = 1 is 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 (5), it is preferable to show a numerical value of 0.1 ≦ d2 ≦ 0.5.

When 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 for a non-aqueous secondary battery. Because it becomes possible.
Among these, a transition metal oxide represented by the following composition formula (6) is more preferable.
Li _a3 Ni _b3 Co _c3 M _d3 O ₂ (6)
(In 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
3 + d3 = 1 is 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 (6), it is preferable to show a numerical value of 0.1 ≦ d3 ≦ 0.5.

Among these, a 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 the formula (7), 0.9 ≦ a4 ≦ 1.1, 0.5 ≦ b4 ≦ 0.9, 0.1 ≦ c4 ≦ 0.2,
The numerical value of 0.0 ≦ d4 ≦ 0.3 is shown, and c4 <b4 and 0.7 ≦ b4 + c4 and b4 + c4.
+ D4 = 1 is 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 (7), it is preferable to show a numerical value of 0.1 ≦ d4 ≦ 0.3.

It is because it becomes possible to take out especially high capacity | capacitance when it is used as a non-aqueous secondary battery positive electrode because it is said composition.
Further, two or more of the positive electrode active materials may be mixed and used. Similarly, at least one of the positive electrode active materials may be mixed with another positive electrode active material. Examples of other positive electrode active materials include transition metal oxides, transition metal phosphate compounds, transition metal silicate compounds, and transition metal borate compounds not listed above.

Among these, lithium manganese composite oxide having a spinel structure and a lithium-containing transition metal phosphate compound having an olivine structure are preferable. Specifically, LiMn ₂ O ₄ , LiMn _1.8 Al _0.2 O ₄ , Li as a lithium manganese composite oxide having a spinel structure
Mn _1.5 Ni _0.5 O ₄ and the like. This is because the structure is most stable, oxygen is not easily released even when the non-aqueous electrolyte secondary battery is abnormal, and safety is excellent.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn,
Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, 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 , transition metal atoms that are the main components of these lithium transition metal phosphate compounds Some are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, C
Examples include those substituted with other metals such as u, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W.
Among them, a lithium iron phosphate compound is preferable because iron is a very inexpensive metal with abundant resources and less harmful. That is, among the above specific examples, LiFePO ₄ can be given as a more preferable specific example.

(2) Surface coating A material having a composition different from that of the main constituent of the positive electrode active material (hereinafter referred to as “surface adhering substance” as appropriate) 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, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, 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, a method in which they are dissolved or suspended in a solvent and impregnated and added to the positive electrode active material and then dried, or a surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material. Then, it can be made to adhere 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 simultaneously. In addition, when attaching carbon, the method of attaching carbonaceous material mechanically later, for example in the form of activated carbon etc. can also be used.

The mass of the surface adhering substance adhering to the surface of the positive electrode active material is based on the mass of the positive electrode active material.
Preferably it is 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 on the surface of the positive electrode active material, and can improve the battery life. Moreover, when the adhesion amount is within the above range, the effect can be sufficiently exhibited, and resistance is hardly increased without inhibiting the entry and exit of lithium ions.

<< 2-4-2. Positive electrode structure and fabrication method >>
Below, the structure of the positive electrode used for this invention and its preparation method are demonstrated.
(Production method of 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 production of 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 mixed in a dry form into a sheet form are pressure-bonded to the 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 it as a slurry, applying this to a positive electrode current collector and drying it.

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, still more preferably 80% by mass or more, and preferably 99.9% by mass or less. Yes, 99 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. Furthermore, the strength of the positive electrode is sufficient. In addition, the positive electrode active material powder in this invention may be used individually by 1 type, and may use together 2 or more types of a different composition or different powder physical properties by arbitrary combinations and ratios. When two or more active materials are used in combination, the composite oxide containing lithium and manganese is preferably used as a powder component. Cobalt or nickel is an expensive metal with a small amount of resources, and it is not preferable in terms of cost because it uses a large amount of active material in large batteries that require high capacity, such as for automobiles. This is because it is desirable to use manganese as a main transition metal.

(Conductive material)
A known conductive material can be arbitrarily used as the conductive material. 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; and carbonaceous materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a 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, still more preferably 1% by mass or more, and preferably 50% by mass or less. 30 mass% or less is more preferable, and 15 mass% or less is still more preferable. When the content is within the above range, sufficient conductivity can be secured. Furthermore, it is easy to prevent a decrease in battery capacity.

(binder)
The binder used for manufacturing the positive electrode active material layer is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used when manufacturing the electrode.
In the case of the coating method, it is not particularly limited as long as it is a material that is dissolved or dispersed in a liquid medium used at the time of electrode production. Specific examples include polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, and cellulose. , Resin polymers such as nitrocellulose; SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene
Rubbery polymers such as propylene rubber; styrene / butadiene / styrene block copolymers or hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymers), styrene / ethylene / butadiene / ethylene copolymers, styrene -Thermoplastic elastomeric polymers such as isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-
Soft resinous polymers such as 1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF),
Examples include fluorine-based polymers such as polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymers; polymer compositions having ion conductivity of alkali metal ions (particularly lithium ions). In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The binder content 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 mass% or less is more preferable, 40 mass% or less is still more preferable, and 10 mass% or less is especially 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 secured, so that 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 for preparing the slurry for forming the positive electrode active material layer is a solvent that can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as necessary. If it exists, there is no restriction | limiting in particular in the kind, You may use either an aqueous solvent or an organic solvent.

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,
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 and N, N-dimethylaminopropylamine Amines such as diethyl ether and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide and dimethylacetamide;
Examples include aprotic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Thickener)
When an aqueous medium is used as the liquid medium for forming the slurry, it is preferable to make a slurry using a thickener and a latex such as styrene butadiene rubber (SBR). A thickener is usually 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. Specifically, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof Etc. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

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 0.6% by mass or more. Preferably
Moreover, it is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less. When the content is within the above range, the coating property is improved, and further, the ratio of the active material in the positive electrode active material layer becomes sufficient, so that the problem that the battery capacity decreases and the resistance between the positive electrode active materials increases. It is easier to avoid problems.

(Consolidation)
In order to increase the packing density of the positive electrode active material, the positive electrode active material layer obtained by applying the slurry to the current collector and drying is preferably consolidated by a hand press, a roller press or the like. 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 non-aqueous electrolyte solution permeation into the vicinity of the current collector / active material interface does not decrease, and the charge / discharge characteristics particularly at a high current density are good. Become. further,
It becomes difficult for the electrical conductivity between active materials to fall and battery resistance to increase easily.

(Current collector)
There is no restriction | limiting in particular as a material of a positive electrode electrical power collector, A well-known thing can be used arbitrarily.
Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbonaceous materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum, are preferred.

Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foam metal, etc. A carbon thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred.
In addition, you may form a thin film suitably in mesh shape.
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, and 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, sufficient strength required for the current collector can be ensured. Furthermore, the handleability is also improved.
The thickness ratio between the current collector and the positive electrode active material layer is not particularly limited, but (active material layer thickness on one side immediately before non-aqueous electrolyte injection) / (current collector thickness) is preferably 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 hardly generates heat due to Joule heat during high current density charge / discharge. Furthermore, it becomes difficult for the volume ratio of the current collector to the positive electrode active material to increase, and a decrease in battery capacity can be prevented.

(Electrode area)
From the viewpoint of increasing the stability at high output and high temperature, the area of the positive electrode active material layer is preferably larger than the outer surface area of the battery outer case. Specifically, the total electrode area 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. The outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. . 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 the structure in which the positive electrode mixture layer is formed on both surfaces via the current collector foil, the sum of the areas where each surface is calculated separately.

(Discharge capacity)
When the non-aqueous electrolyte 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 (electric capacity when the battery is discharged from a fully charged state to a discharged state) ) Is 1 ampere hour (Ah) or more, since the effect of improving the low temperature discharge characteristics is increased. 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 excessive when a large current is taken out, and the deterioration of the power efficiency can be prevented. Furthermore, the temperature distribution due to the internal heat generation of the battery during pulse charge / discharge does not become too large, the durability of repeated charge / discharge is inferior, and the heat dissipation efficiency is poor against sudden heat generation during abnormalities such as overcharge and internal short circuit. The phenomenon of becoming can be avoided.

(Thickness of positive 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 minus the thickness of the current collector is preferably 10 μm or more, more preferably 20 μm or more, more preferably 200 μm or less, and 100 μm with respect to one surface of the current collector.
m or less is more preferable.

<2-5. Separator>
Usually, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the nonaqueous electrolytic solution of the present invention is usually used by impregnating the separator.
There is no restriction | limiting in particular about the material and shape of a separator, As long as the effect of this invention is not impaired remarkably, a well-known thing can be employ | adopted arbitrarily. Among them, a resin, glass fiber, inorganic material, etc. formed of a material that is stable with respect to the non-aqueous electrolyte solution of the present invention is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention properties is used. Is preferred.

As materials for the resin and the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Although the thickness of the separator is arbitrary, it 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, more preferably 30 μm or less. If the separator is too thin than the above range, the insulating properties and mechanical strength may decrease. On the other hand, if it is thicker than the above range, not only the battery performance such as the rate characteristic may be lowered, but also the energy density of the whole non-aqueous electrolyte secondary battery may be lowered.

Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, and 45%
The above is more preferable, and it is usually 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too smaller than the above range, the membrane resistance tends to increase and the rate characteristics tend to deteriorate. Moreover, when larger than the said range, it exists in the tendency for the mechanical strength of a separator to fall and for insulation to fall.

The average pore diameter of the separator is also arbitrary, but is usually 0.5 μm or less and 0.2 μm.
The following is preferable and is usually 0.05 μm or more. If the average pore diameter exceeds the above range, a short circuit tends to occur. On the other hand, 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. Things are used.

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

<2-6. Battery design>
[Electrode group]
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed via the separator.
And any of the structures which wound the above-mentioned positive electrode plate and negative electrode plate spirally through the above-mentioned separator may be sufficient. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less.
80% or less is preferable. When the electrode group occupancy is below the above range, the battery capacity decreases.
Also, if the above range is exceeded, the void space is small, the battery expands, and the member expands or the vapor pressure of the electrolyte liquid component increases and the internal pressure rises. In some cases, the gas release valve that lowers various characteristics such as storage at high temperature and the like, or releases the internal pressure to the outside is activated.

[Current collection structure]
The current collecting structure is not particularly limited, but in order to more effectively realize the improvement of the discharge characteristics by the non-aqueous electrolyte solution of the present invention, it is necessary to make the structure to reduce the resistance of the wiring part and the joint part. preferable. Thus, when internal resistance is reduced, the effect of using the non-aqueous electrolyte solution of this invention is exhibited especially favorable.

In the case where the electrode group has the laminated structure described above, a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to reduce the resistance by providing a plurality of terminals in the electrode. When the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.

[Exterior case]
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, nickel-plated steel sheets, stainless steel, aluminum or aluminum alloys, magnesium alloys and other laminated metals, or laminated films of resin and aluminum foil (
Laminate film) is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

In the exterior case using the above metals, a laser-sealed, resistance-welded, ultrasonic welding is used to weld the metals together to form a sealed sealed structure, or a caulking structure using the above-mentioned metals via a resin gasket To do. Examples of the outer case using the laminate film include those having a sealed and sealed structure by heat-sealing resin layers.
In order to improve the sealing performance, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a sealed structure, a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin is used. Resins are preferably used.

[Protective element]
As the above-described protective element, PTC (Po) increases in resistance when abnormal heat generation or excessive current flows.
Examples thereof include a passive temperature coefficient), a temperature fuse, a thermistor, and a valve (current cutoff valve) that cuts off a current flowing in the circuit due to a sudden rise in battery internal pressure or internal temperature during abnormal heat generation. It is preferable to select a protective element that does not operate under normal use at a high current. 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 housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body. There is no restriction | limiting in this exterior body, A well-known thing can be arbitrarily employ | adopted unless the effect of this invention is impaired remarkably.
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 or the like is used.
The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

EXAMPLES Hereinafter, although an Example and a reference example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples, unless the summary is exceeded.
The structural formulas of compounds 1 to 8 used in the examples and comparative examples are shown below.

<Example 1-1, Comparative Examples 1-1 to 1-5>
[Production 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
Then, 3% by mass of polyvinylidene fluoride (PVdF) as a binder was mixed in a N-methylpyrrolidone solvent with a disperser to form a slurry. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
98 parts by weight of natural graphite, 1 part by weight of an aqueous dispersion of sodium carboxymethylcellulose (concentration of 1% by weight of carboxymethylcellulose sodium) as a thickener and binder, and an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber) 50 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]
Under a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (
EMC), a mixture with diethyl carbonate (DEC) (volumetric volume ratio 3: 4: 3) was dissolved LiPF ₆ sufficiently dried 1.2 mol / L (concentration in the non-aqueous electrolyte),
In addition, vinylene carbonate (VC) and monofluoroethylene carbonate (FEC)
Was added in an amount of 2.0% by mass (referred to as reference electrolyte solution 1). A non-aqueous electrolyte solution was prepared by adding the compounds shown in Table 1 below as additives to the reference electrolyte solution 1. However, Comparative Example 1-1 is the reference electrolyte 1 itself. In addition, "content (mass%)" in the table is
It is the content when the reference electrolyte 1 is 100% by mass.

[Manufacture of non-aqueous electrolyte secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, and the positive electrode to prepare a battery element. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then the non-aqueous electrolyte solution prepared above was placed in the bag. And a vacuum-sealing was performed to produce a laminate-type non-aqueous electrolyte secondary battery.

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
In a constant temperature bath at 25 ° C., the non-aqueous electrolyte secondary battery is subjected to a constant current of 0.05 C (1 C indicates a current value that takes 1 hour to charge or discharge; the same applies hereinafter) for 6 hours. After charging, the battery was discharged at 3.0C to 3.0V. CC-CV charge was performed up to 4.1V at 0.2C. Thereafter, aging was performed at 45 ° C. for 72 hours. Then, 3.0 at 0.2C
The battery was discharged to V to stabilize the nonaqueous electrolyte secondary battery. In addition, C at 0.2C up to 4.4V
After performing C-CV charging, the battery was discharged to 3.0 V at 0.2 C, and initial conditioning was performed.

[Charge storage test]
Recharge the non-aqueous electrolyte secondary battery after initial conditioning to 4.4V at 0.2C.
After performing C-CV charging, high-temperature storage was performed at 85 ° C. for 24 hours. After sufficiently cooling the non-aqueous electrolyte secondary battery, the volume was measured by immersion in an ethanol bath, the amount of generated gas was determined from the volume change before and after the storage test, and this was designated as “charge 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, compared with the phosphorus compounds of the compounds 2 to 5, has a generated gas amount during high-temperature storage of the non-aqueous electrolyte secondary battery. It can be seen that it can be greatly reduced.

<Examples 2-1 to 2-5, Comparative Examples 2-1 to 2-3>
[Production of positive electrode]
A positive electrode similar to that of Example 1-1 was produced.
[Production of negative electrode]
A negative electrode similar to that of Example 1-1 was produced.

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

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

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
In a constant temperature bath at 25 ° C., the non-aqueous electrolyte secondary battery was charged with a constant current for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. CC-CV charge was performed up to 4.1V at 0.2C. Thereafter, aging was performed at 45 ° C. for 72 hours. Then 0.2C
Was discharged to 3.0 V to stabilize the non-aqueous electrolyte secondary battery. Furthermore, it is 4.2 at 0.2C.
After carrying out CC-CV charge to V, it discharged to 3.0V at 0.2C, and performed the initial conditioning.

[Charge storage test]
Recharge the non-aqueous electrolyte secondary battery after initial conditioning to 4.2V at 0.2C.
After performing C-CV charging, high-temperature storage was performed at 85 ° C. for 24 hours. After sufficiently cooling the non-aqueous electrolyte secondary battery, the volume was measured by immersion in an ethanol bath, the amount of generated gas was determined from the volume change before and after the storage test, and this was designated as “charge 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 manufactured 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 produced in Comparative Examples 2-1 and 2-2. Further, as the content of the specific phosphorus compound of the general formula (A) defined in the present invention increases, the gas suppression effect becomes more conspicuous.
In addition, 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, each compound alone can be used. However, the amount of gas generated during high temperature storage is further suppressed.

<Examples 3-1 to 3-4, Comparative Example 3-1>
[Production of positive electrode]
A positive electrode similar to that of Example 1-1 was produced.
[Production of negative electrode]
A negative electrode similar to that of Example 1-1 was produced.

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

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

[Charge storage test]
Recharge the non-aqueous electrolyte secondary battery after initial conditioning to 4.2V at 0.2C.
After performing C-CV charging, high temperature storage was performed under conditions of 60 ° C. and 168 hours. After sufficiently cooling the non-aqueous electrolyte secondary battery, the volume was measured by immersion in an ethanol bath, the amount of generated gas was determined from the volume change before and after the storage test, and this was designated as “charge 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 set to 100.

Here, the charge storage test is performed by changing the high temperature storage conditions with respect to the case of Example 2-1, but as is apparent from Table 3, the specific phosphorus of the general formula (A) defined in the present invention is used. In a non-aqueous electrolyte solution containing a compound and a fluorinated salt or a non-aqueous electrolyte solution containing a specific phosphorus compound of the general formula (C), the non-aqueous electrolyte solution 2 is the same as in Examples 2-1 to 5. It can be seen that the amount of gas generated when the secondary battery is stored at high temperatures can be greatly reduced, and the effects 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>
[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder.
5% by mass was mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

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

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

[Charge storage test]
A charge storage test was conducted 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 set to 100.

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

<Examples 5-1 to 5-3, Comparative Examples 5-1 to 5-3>
[Production of positive electrode]
A positive electrode similar to that of Example 1-1 was produced.
[Production of negative electrode]
A negative electrode similar to that of Example 1-1 was produced.

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

[Manufacture of non-aqueous electrolyte secondary batteries]
A laminate type nonaqueous electrolyte secondary battery was produced in the same manner as in Example 3-1, except that the above nonaqueous electrolyte was used.
<Evaluation of non-aqueous electrolyte secondary battery>
[Initial conditioning]
In the same manner as in Example 3-1, initial conditioning of the non-aqueous electrolyte secondary battery was performed.

[Charge storage test]
Recharge the non-aqueous electrolyte secondary battery after initial conditioning to 4.2V at 0.2C.
After performing C-CV charging, high temperature storage was performed under conditions of 60 ° C. and 168 hours. After sufficiently cooling the non-aqueous electrolyte secondary battery, the volume was measured by immersion in an ethanol bath, the amount of generated gas was determined from the volume change before and after the storage test, and this was designated as “charge storage gas amount”. Example 5 in Table 5 below
-1, 5-2, and 5-3 are the amounts of the charge storage gas of Comparative Examples 5-1, 5-2, and 5-
The ratio of the charge storage gas amount when the charge storage gas amount of 2 is 100 is shown.

As is apparent from Table 5, the non-aqueous electrolyte solution containing the specific phosphorus compound of the general formula (A) defined in the present invention does not contain VC or FEC as an additive, or contains either of them. It can be seen that the amount of gas generated during high-temperature storage of the electrolyte secondary battery can be greatly reduced, and the effects of the present invention can be obtained.

According to the non-aqueous electrolyte of the present invention, the amount of gas generated during high-temperature storage of a non-aqueous electrolyte secondary battery can be improved, and it is useful as a non-aqueous electrolyte for laminate-type batteries.
Moreover, 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,
Notebook PC, pen input PC, mobile PC, electronic book player, mobile phone, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini-disc, transceiver, electronic notebook, calculator , Memory card, portable tape recorder, radio, backup power supply, motor, motorcycle, motorized bicycle, bicycle, lighting equipment, toys, game equipment, clock, electric tool, strobe, camera, home 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 (7)

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

(In the formulas (A), (B) and (C), R ^{1 to} R ³ each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 10 carbon atoms, and X represents an alkyl group having 1 to Represents an alkyl group of 10 or an aryl group having 6 to 18 carbon atoms.) The nonaqueous electrolytic 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 an aryl group having 6 to 18 carbon atoms in the general formulas (A), (B), and (C). The non-aqueous electrolyte solution according to any one of claims 1 to 3, wherein X is a phenyl group in the general formulas (A), (B), and (C). 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 electrolyte solution. The non-aqueous electrolyte solution as described in any one of thru | or 4. 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 a fluorine atom, the fluorinated salt, and the oxalate salt is the non-aqueous electrolyte. The nonaqueous electrolytic solution according to any one of claims 2 to 5, wherein the content is 0.001 mass% or more and 10 mass% or less with respect to the total amount of the liquid. A non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting metal ions, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is according to any one of claims 1 to 6. A non-aqueous electrolyte secondary battery, which is a non-aqueous electrolyte.