JP6201485B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

With the rapid progress of portable electronic devices such as mobile phones and notebook personal computers, there is an increasing demand for higher capacities for batteries used for the main power source and backup power source, such as nickel cadmium batteries and nickel Non-aqueous electrolyte batteries such as lithium ion secondary batteries having higher energy density than hydrogen batteries have attracted attention.
As an electrolytic solution of the lithium ion secondary battery, an electrolyte such as LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃ (CF ₂ ) ₃ SO ₃ is used as a high dielectric constant such as ethylene carbonate or propylene carbonate. A typical example is a non-aqueous electrolyte solution dissolved in a mixed solvent of a solvent and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate.

  In addition, as a negative electrode active material of a lithium ion secondary battery, a carbonaceous material capable of occluding and releasing lithium ions is mainly used, and natural graphite, artificial graphite, amorphous carbon, etc. are listed as representative examples. It is done. Furthermore, metal or alloy negative electrodes using silicon, tin or the like for increasing the capacity are also known. As the positive electrode active material, a transition metal composite oxide capable of mainly inserting and extracting lithium ions is used, and representative examples of the transition metal include cobalt, nickel, manganese, iron and the like.

Such a lithium ion secondary battery uses a highly active positive electrode and negative electrode, and it is known that the charge / discharge capacity decreases due to a side reaction between the electrode and the electrolyte, improving battery characteristics. Therefore, various studies have been made on non-aqueous solvents and electrolytes.
Patent Document 1 or 2 discloses that by adding a diisocyanate compound to a non-aqueous electrolyte solution, the decomposition reaction of the solvent is suppressed by forming a film on the negative electrode, so that the cycle characteristics of the battery and the gas suppression effect during high temperature storage are suppressed. It has been proposed to have
Patent Document 3 discloses a non-aqueous solution in which the positive electrode contains a positive electrode active material coated with phosphate, and the electrolytic solution contains an electrolytic solution containing a non-aqueous solvent, an electrolyte salt, and an isocyanate compound. It has been reported that by using an electrolyte secondary battery, the effect of suppressing swelling during high-temperature storage can be obtained.
Patent Document 4 discloses that the battery characteristics during high-temperature cycle are improved by using a nonaqueous electrolyte battery containing 50 to 1000 ppm of water in the positive electrode and the electrolyte containing an isocyanate compound and an aromatic compound. Has been reported.
Patent Document 5 proposes that a negative electrode having a solid electrolyte coating derived from an isocyanate compound is used for a non-aqueous electrolyte battery, thereby having a battery cycle characteristic and a gas suppressing effect during high-temperature storage.

JP 2005-259641 A US Patent Application Publication No. 2010/0297508 JP 2011-014379 A JP 2011-028860 A JP 2011-048987 A

However, the demand for higher performance of batteries in recent years is increasing, and it is required to achieve various battery characteristics such as high capacity, high temperature storage characteristics, and cycle characteristics at a high level.
As a method for increasing the capacity, for example, by pressing the active material layer of the electrode to increase the density, the volume occupied by the active material other than the active material inside the battery is reduced as much as possible. The method to use is being studied. However, if the active material layer of the electrode is pressurized and densified, it becomes difficult to use the active material uniformly, and some lithium precipitates due to a non-uniform reaction or deterioration of the active material is promoted. The problem that sufficient characteristics cannot be obtained is likely to occur. In addition, when the use range of the positive electrode is expanded to a noble potential, the activity of the positive electrode is further increased, and the problem that the deterioration is accelerated by the reaction between the positive electrode and the electrolytic solution is likely to occur. In particular, when stored under high temperature conditions in a charged state, it is known that the battery capacity decreases due to a side reaction between the electrode and the electrolyte solution. In order to improve storage characteristics, various nonaqueous solvents and electrolytes are used. Consideration has been made.

Furthermore, the increase in capacity reduces the voids inside the battery, and even when a small amount of gas is generated due to the decomposition of the electrolyte, there is a problem that the internal pressure of the battery increases significantly.
Although suppression of the deterioration of the battery characteristics is required, when the additive described in Patent Documents 1 to 2 is contained in the non-aqueous electrolyte, a high-resistance film is formed on the negative electrode. Further, the side reaction of the additive proceeds simultaneously on the positive electrode. As a result, there is a problem that the charge / discharge characteristics under a high current density deteriorate.
In the proposals typified by Patent Documents 3 to 5, depending on the type of diisocyanate compound, the type of additive combined therewith, or the type of electrode, the battery characteristics were not sufficient, and the battery characteristics were not satisfactory. . In these proposals, methyl cellulose and styrene butadiene rubber are described as negative electrode binders, but there is no description about their use amount and use ratio.

  The present invention has been made to solve the above problems, and provides a non-aqueous electrolyte secondary battery that suppresses capacity deterioration during high-temperature storage and improves charge / discharge characteristics under a high current density. Is an issue.

As a result of various studies to achieve the above object, the present inventors have included a specific polyvalent isocyanate compound in the electrolytic solution, and have a synthetic rubber adhesive and a thickening agent as a negative electrode binder. It has been found that the above-mentioned problems can be solved by using a specific amount of the agent, and the present invention has been completed.
That is, the gist of the present invention is as follows.
(A) a non-aqueous electrolyte secondary comprising at least a positive electrode and a negative electrode capable of occluding and releasing metal ions, a separator, and a non-aqueous electrolyte containing a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent In batteries,
(A) The negative electrode contains a synthetic rubber adhesive and a thickener as a negative electrode active material and a binder, and the ratio of the synthetic rubber adhesive to 100 parts by mass of the negative electrode active material is 0.1 parts by mass or more. 5 parts by weight or less, and the ratio of the thickener to 100 parts by weight of the negative electrode active material has a negative electrode active material layer of 0.1 parts by weight or more and 5 parts by weight or less,
(B) The non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte includes at least one compound represented by the following general formula (1).
(In General Formula (1), X is a C3-C10 hydrocarbon group having at least one tertiary or quaternary carbon atom. N represents an integer of 2 to 4.)
(B) X in the general formula (1) has a hydrocarbon group having 1 to 5 carbon atoms as a substituent adjacent to the tertiary or quaternary carbon atom (a) The non-aqueous electrolyte secondary battery described in 1.
(C) X in the general formula (1) has an optionally substituted cyclic hydrocarbon group having 4 to 6 carbon atoms, described in (a) or (b) Non-aqueous electrolyte secondary battery.
(D) The non-aqueous electrolyte secondary battery according to any one of (a) to (c), wherein the synthetic rubber adhesive is styrene butadiene rubber.
(E) The non-aqueous electrolyte secondary battery according to any one of (a) to (d), wherein the thickener is carboxymethyl cellulose or a salt thereof.
(F) The compound represented by the general formula (1) is contained in a nonaqueous electrolytic solution in an amount of 0.001% by mass to 10% by mass, according to any one of (a) to (e), Non-aqueous electrolyte secondary battery.
(G) The non-aqueous electrolyte is a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, a difluorophosphate, an isocyanate compound other than the general formula (1), a cyclic The non-aqueous electrolyte secondary battery according to any one of (a) to (f), which contains at least one compound selected from the group consisting of sulfonic acid esters and cyano compounds.
(H) the cyclic carbonate having a fluorine atom is at least one compound selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate;
The cyclic carbonate having a carbon-carbon unsaturated bond is at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate;
The isocyanate compound other than the general formula (1) is a compound other than the general formula (1) having at least two isocyanate groups,
The non-aqueous electrolyte secondary battery according to (g), wherein the cyano compound is a compound having at least two cyano groups.

According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery that suppresses capacity deterioration during high-temperature storage of a non-aqueous electrolyte secondary battery and has excellent charge / discharge characteristics under a high current density. it can.
The action / principle that the nonaqueous electrolyte secondary battery of the present invention can improve capacity deterioration during high temperature storage and charge / discharge characteristics under high current density is not clear, but is considered as follows. However, the present invention is not limited to the operations and principles described below.

The diisocyanate compounds described in Patent Documents 1 to 5 can react with the hydroxyl group of the binder / thickening agent contained in the negative electrode active material layer or the reduced coating component generated at the negative electrode. When the two isocyanate groups react with the hydroxyl group and the reduced film component, respectively, the diisocyanate compound acts as a film fixing agent on the negative electrode. As a result, elution of the negative electrode film during cycling and storage at high temperatures is suppressed, and battery characteristics are improved.
However, since the diisocyanate compound having a chain hydrocarbon chain composed of secondary carbon atoms as typified by hexamethylene diisocyanate has a high degree of molecular freedom, two isocyanate groups are used as a binder / thickener. It reacts with a hydroxyl group, and the effect as a film fixing agent is hardly exhibited. Therefore, the cycle and high temperature storage characteristics have not been satisfactory yet. Simultaneously with the reaction on the negative electrode, deterioration due to the electrochemical side reaction derived from the isocyanate group proceeds on the positive electrode, and a high-resistance by-product is generated on the electrode. As a result, the charge / discharge characteristics under a high current density are deteriorated. Furthermore, since the cycle characteristics and the high-temperature storage characteristics were also adversely affected, the battery characteristics were still not satisfactory.
In such a problem, by containing the specific isocyanate compound represented by the general formula (1) in the electrolytic solution and using a specific amount of the synthetic rubber adhesive and the thickener as the negative electrode binder, The present inventors have found that the above problem is solved.
Since the compound represented by the general formula (1) has at least one tertiary or quaternary carbon atom in a hydrocarbon chain connecting a plurality of isocyanate groups, only a chain hydrocarbon chain composed of a secondary carbon atom is present. Compared with a polyvalent isocyanate compound having a molecular weight, the degree of molecular freedom is small. Therefore, the probability that a plurality of isocyanate groups react simultaneously with the binder / thickening agent hydroxyl group is reduced, and the effect of the film fixing agent is more strongly expressed. As a result, cycle and high temperature storage characteristics are specifically improved. Furthermore, since the compound represented by the general formula (1) has at least one tertiary or quaternary carbon atom, it is sterically bulky. Therefore, even when acting as a film fixing agent on the negative electrode, it is difficult to adversely affect the insertion and desorption of Li ⁺ , and a decrease in charge / discharge characteristics under a high current density is suppressed. Furthermore, since it is three-dimensionally bulky, it becomes difficult to approach the vicinity of the positive electrode, thereby suppressing electrochemical side reactions. As a result, deterioration of charge / discharge characteristics under a high current density is suppressed.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
A non-aqueous electrolyte secondary battery using the specific non-aqueous electrolyte of the present invention and a negative electrode binder having a specific composition will be described.

1. Non-aqueous electrolyte 1-1. The compound represented by the general formula (1) The present invention is characterized by containing a compound represented by the following general formula (1) in a nonaqueous electrolytic solution.

In the general formula (1), X is a hydrocarbon group having 3 to 10 carbon atoms having at least one tertiary or quaternary carbon atom. n represents an integer of 2 to 4.
In addition, a hydrocarbon group represents the group comprised from the carbon atom and the hydrogen atom here. Further, the hydrocarbon group of X may have a substituent, and specific examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, an alkenylene group, which may be substituted with a halogen atom, Examples include alkynylene group, aryl group, alkoxy group, cyano group, isocyanato group, ether group, carbonate group, carbonyl group, carboxyl group, sulfonyl group, and phosphoryl group.

X in the general formula (1) preferably has a hydrocarbon group having 1 to 5 carbon atoms as a substituent adjacent to the tertiary or quaternary carbon atom. The “substituent adjacent to the tertiary or quaternary carbon atom” means a substituent bonded to the tertiary or quaternary carbon atom, and particularly has the structure of the general formula (1). Among them, it means a structural part that does not contain an isocyanate group (—NCO). The substituent adjacent to the tertiary or quaternary carbon atom is more preferably a saturated chain hydrocarbon group having a hydrocarbon group having 1 to 5 carbon atoms.
Specific examples of the hydrocarbon group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, t-butyl group, 1-methylpropyl group, 2- Methylpropyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2- Examples include dimethylpropyl group, vinyl group, propargyl group, methylene group, ethylene group, propylene group and the like. Of these, a methyl group is preferable. This is because the ratio of isocyanate groups in one molecule is increased.

Moreover, it is preferable that X in the said General formula (1) has a C4-C6 cyclic hydrocarbon group which may have a substituent.
Specific examples of the cyclic hydrocarbon group having 4 to 6 carbon atoms include a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group. Of these, a cyclopentylene group or a cyclohexylene group is preferable, and a cyclohexylene group is more preferable.
Specific examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, an alkenylene group, an alkynylene group, an aryl group, an alkoxy group, a cyano group, an isocyanato group, and an ether group, which may be substituted with a halogen atom. , Carbonate group, carbonyl group, carboxyl group, sulfonyl group, phosphoryl group and the like.
The bonding site of the group bonded to the cyclic hydrocarbon group is not particularly limited and may be any of the meta position, the para position, and the ortho position, but is preferably the meta position.
Moreover, it is preferable that n is 2 from stability of a compound.

  The molecular weight of the compound represented by the general formula (1) 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 180 or more, more preferably 200 or more, and 350 or less, preferably 250 or less. If it is this range, it will be easy to ensure the solubility of the compound shown by General formula (1) with respect to a non-aqueous 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 the following compounds.

  Of these, the following compounds are preferred.

  The compound represented by the general formula (1) may be used alone or in combination of two or more in any combination. The compounding amount of the compound represented by the general formula (1) with respect to the whole non-aqueous electrolyte of the present invention is not limited and is arbitrary as long as the effects of the present invention are not significantly impaired, but with respect to the non-aqueous electrolyte of the present invention. Usually, 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. It is made to contain with the density | concentration. When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-2. The present invention relates to a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, a difluorophosphate, an isocyanate compound other than the general formula (1), a cyclic sulfonate, and a cyano compound. The non-aqueous electrolyte further includes a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, a difluorophosphate, an isocyanate compound other than the general formula (1), and a cyclic sulfonic acid. Those containing at least one compound selected from the group consisting of esters and cyano compounds are preferred. It is because the side reaction caused by each additive can be efficiently suppressed by using these together.
In particular, the cyclic carbonate having a fluorine atom and the cyclic carbonate having a carbon-carbon unsaturated bond form a stable composite protective film on the surface of the compound represented by the general formula (1) and the negative electrode, and the negative electrode and the electrolyte component. This is more preferable because the high temperature storage characteristics and cycle characteristics can be improved.
Hereinafter, each of a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, a difluorophosphate, an isocyanate compound other than the general formula (1), a cyclic sulfonate, and a cyano compound Will be described in detail.

1-2-1. The cyclic carbonate having a fluorine atom The cyclic carbonate having a fluorine atom (hereinafter sometimes referred to as “fluorinated cyclic carbonate”) is not particularly limited as long as it is a cyclic carbonate having a fluorine atom.

  Examples of the fluorinated cyclic carbonate include a fluorinated product of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof, and examples thereof include a fluorinated product of ethylene carbonate and derivatives 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.

In particular,
Monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methyl Ethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoro Methyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene Boneto, 4,4-difluoro-5,5-dimethylethylene 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.
A fluorinated cyclic 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 fluorinated cyclic carbonate is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and preferably 1% by mass or more with respect to the non-aqueous electrolyte solution. It is 10 mass% or less, More preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less. The blending amount when fluorinated cyclic carbonate is used as the non-aqueous solvent is preferably 100% by volume in the non-aqueous solvent, preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more. Moreover, it is preferably 50% by volume or less, more preferably 35% by volume or less, and further preferably 25% by volume or less.
If it is within the above range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristic improvement effect, and avoids a decrease in discharge capacity maintenance rate due to a decrease in high-temperature storage characteristics or an increase in gas generation amount. It's easy to do.

  The compound represented by the general formula (1) and the cyclic carbonate having a fluorine atom form a composite film on the negative electrode. From the viewpoint of satisfactorily forming such a film, the blending mass ratio of the compound represented by the general formula (1) and the fluorinated cyclic carbonate is preferably 0.4: 100 to 100: 100, and 1: It is more preferable that it is 100-50: 100, and it is further more preferable that it is 1.4: 100-35: 100. When it mix | blends in this range, the side reaction in the positive / negative electrode of each additive can be suppressed efficiently, and a battery characteristic improves.

1-2-2. Cyclic carbonate having carbon-carbon unsaturated bond Cyclic carbonate having carbon-carbon unsaturated bond (hereinafter sometimes referred to as “unsaturated cyclic carbonate”) includes a carbon-carbon double bond or a carbon-carbon triple bond. Any cyclic carbonate having a bond is not particularly limited, and any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

As unsaturated cyclic carbonate,
Examples include vinylene carbonates, ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond or carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates, and the like. .

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-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 or a carbon-carbon double bond or a carbon-carbon triple bond include:
Vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5 -Ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl Examples include -5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, and the like.

Among these, as an unsaturated cyclic carbonate preferable for use in combination with the compound represented by the general formula (1),
Vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5 -Diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate. Vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are particularly preferable because they form 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 or more, and more preferably 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. Moreover, the compounding quantity of unsaturated cyclic carbonate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The blending amount of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.1% by mass or more, in 100% by mass of the non-aqueous electrolyte solution. Moreover, Preferably it is 5 mass% or less, More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristic improving effect, the high temperature storage characteristic is lowered, the amount of gas generation is increased, and the discharge capacity maintenance rate is lowered. Easy to avoid the situation.

1-2-3. Monofluorophosphate and difluorophosphate There are no particular limitations on the countercation of monofluorophosphate and difluorophosphate, but lithium, sodium, potassium, magnesium, calcium, and NR ¹¹ R ¹² R ¹³ R ¹⁴ (wherein, R ^{11 to} R ¹⁴ each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms), and the like.

Although it does not specifically limit as a C1-C12 organic group represented by R < ¹¹ > -R < ¹⁴ > of 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 these, as R ^{11 to} R ¹⁴ , a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group is preferable.

Specific examples of monofluorophosphate and difluorophosphate include
Lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate and the like, lithium monofluorophosphate and lithium difluorophosphate are preferred, More preferred is lithium difluorophosphate.

Monofluorophosphate and difluorophosphate may be used singly or in combination of two or more in any combination and ratio. Moreover, the compounding quantity of a monofluoro phosphate and a difluoro phosphate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary.
The blending amount of monofluorophosphate and difluorophosphate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% in 100% by mass of the non-aqueous electrolyte. It is at least 5% by mass, preferably at most 5% by mass, more preferably at most 4% by mass, even more preferably at most 3% by mass.
Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristic improving effect, the high temperature storage characteristic is lowered, the amount of gas generation is increased, and the discharge capacity maintenance rate is lowered. Easy to avoid the situation.

1-2-4. Isocyanate compound other than general formula (1) The type of isocyanate compound other than general formula (1) is not particularly limited as long as it is a compound other than general formula (1) having an isocyanate group in the molecule.
Specific examples of isocyanate compounds other than the general formula (1) include, for example,
Monoisocyanates such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, tertiary butyl isocyanate, pentyl isocyanate hexyl isocyanate, cyclohexyl isocyanate, vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propynyl isocyanate, phenyl isocyanate, fluorophenyl isocyanate Compound;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 -Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1, 4-diisocyanatocyclohexane, dicyclohexylmethane-1,1′-diisocyanate, dicyclohexylmethane-2,2′-diisocyanate, dicyclohexylmethane-3,3′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate , Diisocyanate compounds such as carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, 1,5-diisocyanatopentane-1,5-dione;
Etc.

  Among these, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, dicyclohexylmethane Diisocyanate compounds such as -4,4'-diisocyanate and isophorone diisocyanate are preferred from the viewpoint of improving storage characteristics.

The isocyanate compound other than the general formula (1) used in the present invention may be a trimer compound derived from a compound having at least two isocyanate groups, or an aliphatic polyisocyanate to which a polyhydric alcohol is added. Good. Examples thereof include biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of the following general formulas (3-1) to (3-4) (the following general formula (3-1) ) To (3-4), R and R ′ are each independently an arbitrary hydrocarbon group).

  Isocyanate compounds other than the general formula (1) used in the present invention include so-called blocked isocyanates that are blocked with a blocking agent to enhance storage stability. Examples of the blocking agent include alcohols, phenols, organic amines, oximes, and lactams. Specific examples include n-butanol, phenol, tributylamine, diethylethanolamine, methyl ethyl ketoxime, and ε-caprolactam. Etc.

For the purpose of accelerating the reaction based on isocyanate compounds other than the general formula (1) and obtaining higher effects, a metal catalyst such as dibutyltin dilaurate or the like, and 1,8-diazabicyclo [5.4.0] undecene-7 It is also preferable to use such an amine catalyst together.
Furthermore, isocyanate compounds other than general formula (1) may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

There is no restriction | limiting in the compounding quantity of isocyanate compounds other than General formula (1) with respect to the whole nonaqueous electrolyte solution of this invention, and it is arbitrary unless the effect of this invention is impaired remarkably, With respect to the nonaqueous electrolyte solution of this invention Usually, 0.001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. It is made to contain with the density | concentration.
When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-2-5. Cyclic sulfonic acid ester The cyclic sulfonic acid ester is not particularly limited as long as it is a sulfonic acid ester having a cyclic structure.
Specific examples of the cyclic sulfonate ester include, for example,
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-propene -1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3 -Methyl-2-propene-1,3-sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4 -Fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, 1 -Butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro- -Butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1,4-sultone 2-fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1-fluoro-3-butene -1,4-sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1 -Methyl-1-butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1 , 4-sultone, 1-methyl-2-butene-1,4 -Sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3 -Butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, 4-methyl-3-butene-1,4-sultone 1,5-pentane sultone, 1-fluoro-1,5-pentane sultone, 2-fluoro-1,5-pentane sultone, 3-fluoro-1,5-pentane sultone, 4-fluoro-1,5-pentane Sultone, 5-fluoro-1,5-pentanthruton, 1-methyl-1,5-pentanthruton, 2-methyl-1,5-pentanthruton, 3-methyl-1,5-pentanthruton, 4-methyl- 1,5- N-pentene sultone, 5-methyl-1,5-pentanthrutone, 1-pentene-1,5-sultone, 2-pentene-1,5-sultone, 3-pentene-1,5-sultone, 4-pentene-1,5 -Sultone, 1-fluoro-1-pentene-1,5-sultone, 2-fluoro-1-pentene-1,5-sultone, 3-fluoro-1-
Pentene-1,5-sultone, 4-fluoro-1-pentene-1,5-sultone, 5-fluoro-1-pentene-1,5-sultone, 1-fluoro-2-pentene-1,5-sultone, 2-fluoro-2-pentene-1,5-sultone, 3-fluoro-2-pentene-1,5-sultone, 4-fluoro-2-pentene-1,5-sultone, 5-fluoro-2-pentene- 1,5-sultone, 1-fluoro-3-pentene-1,5-sultone, 2-fluoro-3-pentene-1,5-sultone, 3-fluoro-3-pentene-1,5-sultone, 4- Fluoro-3-pentene-1,5-sultone, 5-fluoro-3-pentene-1,5-sultone, 1-fluoro-4-pentene-1,5-sultone, 2-fluoro-4-pentene-1, 5-sul 3-fluoro-4-pentene-1,5-sultone, 4-fluoro-4-pentene-1,5-sultone, 5-fluoro-4-pentene-1,5-sultone, 1-methyl-1- Pentene-1,5-sultone, 2-methyl-1-pentene-1,5-sultone, 3-methyl-1-pentene-1,5-sultone, 4-methyl-1-pentene-1,5-sultone, 5-methyl-1-pentene-1,5-sultone, 1-methyl-2-pentene-1,5-sultone, 2-methyl-2-pentene-1,5-sultone, 3-methyl-2-pentene- 1,5-sultone, 4-methyl-2-pentene-1,5-sultone, 5-methyl-2-pentene-1,5-sultone, 1-methyl-3-pentene-1,5-sultone, 2- Methyl-3-pentene-1,5-sul 3-methyl-3-pentene-1,5-sultone, 4-methyl-3-pentene-1,5-sultone, 5-methyl-3-pentene-1,5-sultone, 1-methyl-4- Pentene-1,5-sultone, 2-methyl-4-pentene-1,5-sultone, 3-methyl-4-pentene-1,5-sultone, 4-methyl-4-pentene-1,5-sultone, Sultone compounds such as 5-methyl-4-pentene-1,5-sultone;

Sulfate compounds such as methylene sulfate, ethylene sulfate, propylene sulfate;
Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazol-2,2-dioxide 5H-1,2,3-oxathiazol-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 4-methyl-1,2,4-oxathiazolidine-2,2- Dioxide, 3H-1,2,4-oxathiazole-2,2-dioxide, 5H-1,2,4-oxathiazole-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide 5-methyl-1,2,5-oxathiazolidine-2,2-dioxide, 3H-1,2,5-oxathiazole-2,2-dioxide, 5H-1,2,5-oxathiazole-2 2-dioxide, 1,2,3-oxathiazinane-2,2-dioxide, 3-methyl-1,2,3-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine- 2,2-dioxide, 1,2,4-oxathiazinane-2,2-dioxide, 4-methyl-1,2,4-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,4- Oxathiazine-2,2-dioxide, 3,6-dihydro-1,2,4-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,4-oxathiazine-2,2-dioxide, 1, 2,5-oxathiazinane-2,2-dioxide, 5-methyl-1,2,5-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,5-oxathiazine-2 2-dioxide, 3,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,5-oxathiazine-2,2-dioxide, 1,2,6- Oxathiazinane-2,2-dioxide, 6-methyl-1,2,6-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide, 3,4- Nitrogen-containing compounds such as dihydro-1,2,6-oxathiazine-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide;

1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathi Aphoslane-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphoslane-2,2,3-trioxide, 1,2,4-oxathiaphoslane-2,2-dioxide 4-methyl-1,2,4-oxathiaphoslane-2,2-dioxide, 4-methyl-1,2,4-oxathiaphoslane-2,2,4-trioxide, 4-methoxy-1 , 2,4-Oxathiaphoslane-2,2,4-trioxide, 1,2,5-oxathiaphoslane-2,2-dioxide, 5-methyl-1,2,5-oxathiaphoslane- 2,2-dioxide, 5-methyl-1,2,5-oxathia Suranium-2,2,5-trioxide, 5-methoxy-1,2,5-oxathiaphoslane-2,2,5-trioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 3-methoxy-1, 2,3-oxathiaphosphinan-2,2,3-trioxide, 1,2,4-oxathiaphosphinan-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2 , 2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 4-methyl-1,5,2,4-dioxathiaphosphinan-2,4- Dioxide, 4-methoxy 1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 3-methoxy-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 1,2,5-oxa Thiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan-2,2, 3-trioxide, 5-methoxy-1,2,5-oxathiaphosphinan-2,2,3-trioxide, 1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1, 2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinan-2,2,3-trioxide, 6-methoxy-1,2,6-oxathia Phosphinan-2,2 Phosphorus-containing compounds such as 1,3-trioxide;
Etc.

Of these,
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1,4-butane sultone, methylenemethane Disulfonate, ethylene methane disulfonate is preferred from the viewpoint of improving storage characteristics,
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone More preferred.

  A cyclic sulfonic acid ester may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. There is no limitation on the amount of the cyclic sulfonate ester added to the entire non-aqueous electrolyte of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. It is contained at a concentration of not less than mass%, preferably not less than 0.1 mass%, more preferably not less than 0.3 mass%, and usually not more than 10 mass%, preferably not more than 5 mass%, more preferably not more than 3 mass%. . When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-2-6. Cyano Compound The cyano compound is not particularly limited as long as it is a compound having a cyano group in the molecule.
Specific examples of the cyano compound 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-diph Oropropionitrile, 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, 2-cyanoethyl methanesulfonate ;

Malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl- 2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2,2-dicarbonitrile, bicyclohexyl- , 3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-3,3-dimethylsuccino Nitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetra Methylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-disi Nobenzene, 1,4-dicyanobenzene, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipropionitrile, 3,9-bis (2-cyanoethyl) -2,4 , 8,10-tetraoxaspiro [5,5] undecane and other compounds having two cyano groups;
Compounds having three cyano groups such as cyclohexanetricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, pentanetricarbonitrile, propanetricarbonitrile, heptanetricarbonitrile;
Etc.

Of these,
Lauronitrile, crotononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, fumaronitrile, 3,9-bis (2-cyanoethyl) -2,4 8,10-Tetraoxaspiro [5,5] undecane is more preferable from the viewpoint of improving storage characteristics. Also, succinonitrile, glutaronitrile, adiponitrile, pimeonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, fumaronitrile, 3,9-bis (2-cyanoethyl) -2,4,8,
A compound having two cyano groups (dicyano compound) such as 10-tetraoxaspiro [5,5] undecane is particularly preferable.

  A cyano compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. There is no limitation on the amount of the cyano compound added to the whole non-aqueous electrolyte solution of the present invention, and it is optional as long as the effect of the present invention is not significantly impaired, but usually 0.001% by mass with respect to the non-aqueous electrolyte solution of the present invention. Above, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% 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 output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-3. Electrolyte <Lithium salt>
As the electrolyte, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used. Specific examples include the following.

For example, inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ ; Lithium tungstates such as LiWOF ₅ ;
HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ Lithium carboxylates such as CO ₂ Li, CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, Sulfonic acid lithium salts such as CF ₃ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ Li; LiN (FCO) ₂ , LiN (FCO) (FSO ₂ ) _{, LiN (FSO 2) 2,} LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN (C 2 F 5 S _{2) 2,} lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2) lithium imide salts such as ;

Lithium metide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ;
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;
In addition, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C _{2 F 5, LiBF 3 C 3} F 7, LiBF 2 (CF 3) 2, LiBF 2 (C 2 F 5) 2, LiBF 2 (CF 3 SO 2) 2, LiBF 2 (C 2 F 5 SO 2) 2 Fluorine-containing organic lithium salts such as;

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃ C _{2 F 5, LiPF 3 (CF} 3) _{, LiPF 3 (C 2 F 5} ) 3 or the like is output characteristics and high-rate discharge characteristics, high-temperature storage characteristics, particularly preferred from the viewpoint that an effect of improving the cycle characteristics and the like.

These lithium salts may be used alone or in combination of two or more. A preferable example in the case of using two or more types in combination is a combination of LiPF ₆ and LiBF ₄ or LiPF ₆ and FSO ₃ Li, which has an effect of improving load characteristics and cycle characteristics.
In this case, the concentration of LiBF ₄ or FSO ₃ Li with respect to 100% by mass of the entire non-aqueous electrolyte solution is not limited as long as it does not significantly impair the effects of the present invention. On the other hand, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less.

Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of both has the effect of suppressing deterioration due to high-temperature storage. As the organic lithium salt, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , Lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) ₃ or the like is preferable. In this case, the ratio of the organic lithium salt to 100% by mass of the whole non-aqueous electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and preferably 30% by mass or less. Especially preferably, it is 20 mass% or less.

The concentration of these lithium salts in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range, and good battery performance is ensured. Therefore, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and further preferably 0.5 mol / L or more. Preferably it is 3 mol / L or less, More preferably, it is 2.5 mol / L or less, More preferably, it is 2.0 mol / L or less.
If the total molar concentration of lithium is too low, the electrical conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to an increase in viscosity, resulting in decreased battery performance. There is a case.

1-4. Nonaqueous solvent There is no restriction | limiting in particular about the nonaqueous solvent in this invention, It is possible to use a well-known organic solvent. Examples thereof include cyclic carbonates having no fluorine atom, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, sulfone compounds, and the like.

<Cyclic carbonate not having fluorine atoms>
Examples of the cyclic carbonate having no fluorine atom include cyclic carbonates having an alkylene group having 2 to 4 carbon atoms.
Specific examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms and having no fluorine atom include ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

  The cyclic carbonate which does not have a fluorine atom may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.

  The blending amount of the cyclic carbonate not having a fluorine atom 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 blending amount when using one kind alone is a non-aqueous solvent. In 100 volume%, it is 5 volume% or more, More preferably, it is 10 volume% or more. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the high current discharge characteristics, stability against the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery are in a good range. And it will be easier. Moreover, an upper limit is 95 volume% or less, More preferably, it is 90 volume% or less, More preferably, it is 85 volume% or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in ionic conductivity is suppressed, and as a result, the load characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range.

<Chain carbonate>
As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
Specific examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl. Examples include carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, t-butyl ethyl carbonate, and the like.

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

The number of fluorine atoms 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 fluorinated dimethyl carbonate and derivatives thereof, fluorinated ethyl methyl carbonate and derivatives thereof, and fluorinated diethyl carbonate and derivatives thereof.

Fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like. It is done.
Fluorinated ethyl methyl carbonate and derivatives thereof include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate, etc. are mentioned.

Fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, Examples include 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, and the like.
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 amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, the decrease in ionic conductivity is suppressed, and consequently the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range. Become. Further, the chain carbonate is preferably 90% by volume or less, more preferably 85% by volume or less, in 100% by volume of the nonaqueous solvent. By setting the upper limit in this way, it is easy to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte and to make the large current discharge characteristics of the non-aqueous electrolyte secondary battery in a favorable range. .

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

A cyclic carboxylic acid ester may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the cyclic carboxylic acid ester is usually 5% by volume or more, more preferably 10% by volume or more, in 100% by volume of the non-aqueous solvent. If it is this range, it will become easy to improve the electrical conductivity of a non-aqueous electrolyte solution, and to improve the large current discharge characteristic of a non-aqueous electrolyte secondary battery. Moreover, the compounding quantity of cyclic carboxylic acid ester becomes like this. Preferably it is 50 volume% or less, More preferably, it is 40 volume% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

<Chain carboxylic acid ester>
The chain carboxylic acid ester is preferably one having 3 to 7 carbon atoms. In particular,
Methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, propion Acid-n-butyl, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, butyric acid n-propyl, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, isobutyric acid n-propyl, isopropyl isobutyrate Etc.

Among them, methyl acetate, ethyl acetate, acetate-n-propyl, acetate-n-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. It is preferable from the viewpoint of improvement of ionic conductivity.
A chain carboxylic acid ester may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The compounding amount of the chain carboxylic acid ester is usually 10% by volume or more, more preferably 15% by volume or more, in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily improved. Moreover, the compounding quantity of chain | strand-shaped carboxylic acid ester is 60 volume% or less preferably in 100 volume% of nonaqueous solvents, More preferably, it is 50 volume% or less. By setting the upper limit in this manner, an increase in negative electrode resistance is suppressed, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range.

<Ether compound>
As the ether compound, a chain ether having 3 to 10 carbon atoms in which part of hydrogen may be substituted with fluorine, and a cyclic ether having 3 to 6 carbon atoms are preferable.
As the chain ether having 3 to 10 carbon atoms,
Diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2, 2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2-trifluoroethyl) ether, (2-fluoroethyl) ) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propyl ether, ethyl (3-Fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-teto Fluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propylether, (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-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro- n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1, 1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro -N-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propyl ether, (n- Propyl) (3-fluoro (Ro-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) ether ) (2, 2, 3, 3- Trifluoro-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-tri Fluoroethoxy) methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2 2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) Methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1,1 , 2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2,2 -Trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy Ci (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2 -Fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) Ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n- Examples include propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

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

An ether type compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the ether compound is usually in 100% by volume of the non-aqueous solvent, preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, and preferably 70% by volume or less. More preferably, it is 60 volume% or less, More preferably, it is 50 volume% or less.
If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall, and when a negative electrode active material is a carbonaceous material, a chain ether with lithium ion It is easy to avoid a situation where the capacity is reduced due to co-insertion.

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

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 the sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter sometimes referred to as “sulfolanes” including sulfolane) are preferable. 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-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output characteristics.

In addition, as the chain sulfone having 2 to 6 carbon atoms,
Dimethylsulfone, ethylmethylsulfone, diethylsulfone, n-propylmethylsulfone, n-propylethylsulfone, di-n-propylsulfone, isopropylmethylsulfone, isopropylethylsulfone, diisopropylsulfone, n-butylmethylsulfone, n-butylethyl Sulfone, t-butylmethylsulfone, t-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoro Ethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, perf Oroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl- n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoroethylisopropylsulfone , Trifluoroethyl-n-butylsulfone, trifluoroethyl-t-butylsulfone, pentafluoroethyl- - butyl sulfone, pentafluoroethyl -t- butyl sulfone, and the like.

Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl 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, trifluoromethyl -t- butyl sulfone is high ion conductivity, preferable because the input-output characteristic is high.

A sulfone type compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the sulfone compound is usually 0.3% by volume or more, more preferably 1% by volume or more, further preferably 5% by volume or more in 100% by volume of the nonaqueous solvent, and preferably 40%. Volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less.
Within this range, durability improvement effects such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set within an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

<When using a cyclic carbonate having a fluorine atom as a non-aqueous solvent>
In the present invention, when a cyclic carbonate having a fluorine atom is used as a non-aqueous solvent, one of the non-aqueous solvents exemplified above is combined with a cyclic carbonate having a fluorine atom as a non-aqueous solvent other than the cyclic carbonate having a fluorine atom. Two or more kinds may be used in combination with a cyclic carbonate having a fluorine atom.

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

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

Among the combinations of cyclic carbonates having a fluorine atom and chain carbonates, those containing symmetric chain alkyl carbonates as chain carbonates are more preferable, and in particular, monofluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, Cycle characteristics include monofluoroethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as fluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. And a large current discharge characteristic are preferable. Among these, the symmetric chain carbonate is preferably dimethyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

  A combination in which a cyclic carbonate not having a fluorine atom is further added to the combination of the cyclic carbonate having a fluorine atom and the chain carbonate is also a preferable combination. Among them, the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom in the non-aqueous solvent is preferably 10% by volume or more, more preferably 15% by volume or more, and further preferably 20% by volume or more. The ratio of the cyclic carbonate having a fluorine atom to the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom is 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume. % Or more, more preferably 25% by volume or more, preferably 95% by volume or less, more preferably 85% by volume or less, still more preferably 75% by volume or less, and particularly preferably 60% by volume or less.

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

  Among the combinations of a cyclic carbonate having a fluorine atom and a cyclic carbonate having no fluorine atom and a chain carbonate, those containing a symmetric chain alkyl carbonate as the chain carbonate are more preferable, and in particular, monofluoroethylene Carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, Ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, monofluoroethylene Carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoro Symmetrical to monofluoroethylene carbonate such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate Those containing Jo carbonate and an asymmetric chain carbonate is preferred because good balanced cycle characteristics and large-current discharge characteristics. Among them, the symmetric chain carbonate is preferably dimethyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

  When dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 25% by volume or more. Preferably, the content is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. The load characteristics may be improved.

Above all, it contains dimethyl carbonate and ethyl methyl carbonate, and by increasing the content ratio of dimethyl carbonate over the content ratio of ethyl methyl carbonate, the electric conductivity of the electrolyte can be maintained, but the battery characteristics after high temperature storage are improved. Therefore, it is preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents (dimethyl carbonate / ethyl methyl carbonate) is 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferable, 1.5 or more is more preferable, and 2.5 or more is more preferable.

The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.
In the combination mainly composed of the cyclic carbonate having a fluorine atom and the chain carbonate, in addition to the cyclic carbonate having no fluorine atom, a cyclic carboxylic acid ester, a chain carboxylic acid ester, a cyclic ether, Other solvents such as chain ethers, sulfur-containing organic solvents, phosphorus-containing organic solvents, and fluorine-containing aromatic solvents may be mixed.

<When using a cyclic carbonate having a fluorine atom as an auxiliary agent>
In the present invention, when a cyclic carbonate having a fluorine atom is used as an auxiliary agent, as the non-aqueous solvent other than the cyclic carbonate having a fluorine atom, the above-exemplified non-aqueous solvent may be used alone, or two or more thereof. May be used in any combination and ratio.
For example, one preferred combination of non-aqueous solvents is a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate.

  Among them, the total of cyclic carbonate and chain carbonate having no fluorine atom in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, and still more preferably 90% by volume or more, The ratio of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more. Preferably it is 50 volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less, Most preferably, it is 25 volume% or less.

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

  Among the combinations of cyclic carbonates and chain carbonates not having a fluorine atom, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, in particular, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, Those containing ethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate have cycle characteristics and large current discharge characteristics. This is preferable because of a good balance.

Among them, the asymmetric chain carbonate is preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
A combination in which propylene carbonate is further added to the combination of these ethylene carbonates and chain carbonates is also a preferable combination.
In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Further, the proportion of propylene carbonate in the whole non-aqueous solvent is preferably 0.1% by volume or more, more preferably 1% by volume or more, further preferably 2% by volume or more, and preferably 20% by volume or less, more preferably Is 8% by volume or less, more preferably 5% by volume or less.

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

Above all, it contains dimethyl carbonate and ethyl methyl carbonate, and by increasing the content ratio of dimethyl carbonate over the content ratio of ethyl methyl carbonate, the electric conductivity of the electrolyte can be maintained, but the battery characteristics after high temperature storage are improved. This is preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents (dimethyl carbonate / ethyl methyl carbonate) is 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferable, 1.5 or more is more preferable, and 2.5 or more is more preferable. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.

In the combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate, a cyclic carboxylic acid ester, a chain carboxylic acid ester, a cyclic ether, a chain ether, a sulfur-containing organic solvent, You may mix other solvents, such as a phosphorus organic solvent and an aromatic fluorine-containing solvent.
In this specification, the volume of the non-aqueous solvent is a measured value at 25 ° C., but the measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.

1-5. Auxiliary Agent In the non-aqueous electrolyte secondary battery of the present invention, an auxiliary agent may be appropriately used depending on the purpose in addition to the compound represented by the general formula (1). Examples of auxiliary agents include unsaturated cyclic carbonates having fluorine atoms, overcharge inhibitors, and other auxiliary agents as shown below.

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

Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with an aromatic ring or a substituent having a carbon-carbon double bond.
Fluorinated vinylene carbonate derivatives include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

As the fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond,
4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene Carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fu Oro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate.

Among them, as a fluorinated unsaturated cyclic carbonate particularly preferable for use in combination with the compound represented by the general formula (1),
4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-4-vinyl ethylene carbonate, 4-fluoro- 4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl ethylene carbonate, because it forms a stable interface protective coating, more preferably used.

The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 50 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the fluorinated cyclic carbonate with respect to non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed.
The production method of the fluorinated unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

A fluorinated unsaturated cyclic carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Further, the blending amount of the fluorinated unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired.
The compounding amount of the fluorinated unsaturated cyclic carbonate is usually 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, in 100% by mass of the nonaqueous electrolytic solution. Moreover, it is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% 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 generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid the situation.

<Overcharge prevention agent>
In the non-aqueous electrolyte solution of the present invention, an overcharge inhibitor can be used in order to effectively suppress battery explosion / ignition when the non-aqueous electrolyte secondary battery is in an overcharged state or the like. .
As an overcharge prevention agent,
Aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenylether, dibenzofuran; 2-fluorobiphenyl, o-cyclohexylfluorobenzene, p -Partially fluorinated product of the above aromatic compound such as cyclohexylfluorobenzene;
Examples thereof include fluorine-containing anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole. Among them, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable.

  These may be used alone or in combination of two or more. When two or more kinds are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, Using at least one selected from aromatic compounds not containing oxygen, such as t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether, dibenzofuran, and the like is an overcharge prevention property and a high temperature storage property. From the standpoint of balance.

The amount of the overcharge inhibitor is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The overcharge inhibitor is preferably 0.1% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. If it is this range, it will be easy to fully express the effect of an overcharge inhibiting agent, and it will be easy to avoid the situation where the characteristics of batteries, such as a high temperature storage characteristic, fall.
The overcharge inhibitor is more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.5% by mass or more, and more preferably 3% by mass or less, still more preferably. Is 2% by mass or less.

<Other auxiliaries>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. As other auxiliaries,
Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate;
Succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, phenylsuccinic anhydride, And carboxylic anhydrides such as 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride;

Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane;
Ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, vinyl Methyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl sulfonate, propargyl allyl sulfonate, 1,2-bis (vinylsulfonoxy) Sulfur-containing compounds such as ethane;
Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide;
Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, diethylphospho Phosphorus-containing compounds such as ethyl noacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide;

Hydrocarbon compounds such as heptane, octane, nonane, decane, cycloheptane;
Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride;
Etc. 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 blending amount of other auxiliary agents is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The other auxiliary agent is preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. Within this range, the effects of other auxiliaries can be sufficiently exhibited, and it is easy to avoid a situation in which battery characteristics such as high-load discharge characteristics deteriorate.
The blending amount of other auxiliaries is more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, more preferably 3% by mass or less, and further preferably 1% by mass or less. .

As mentioned above, what exists in the inside of the non-aqueous electrolyte secondary battery as described in this invention is also contained in the above-mentioned non-aqueous electrolyte.
Specifically, the components of the non-aqueous electrolyte such as lithium salt, solvent, and auxiliary agent are separately synthesized, and the non-aqueous electrolyte is prepared from the substantially isolated one by the method described below. In the case of a non-aqueous electrolyte solution in a non-aqueous electrolyte secondary battery obtained by pouring into a separately assembled battery, the components of the non-aqueous electrolyte solution of the present invention are individually placed in the battery, When the same composition as the non-aqueous electrolyte of the present invention is obtained by mixing in the battery, further, the compound constituting the non-aqueous electrolyte of the present invention is generated in the non-aqueous electrolyte secondary battery, The case where the same composition as the non-aqueous electrolyte solution of the present invention is obtained is also included.

2. Negative electrode The non-aqueous electrolyte secondary battery of the present invention can take a known structure, and typically includes a negative electrode and a positive electrode capable of occluding and releasing ions (for example, lithium ions), and the above-described present invention. The negative electrode is provided with a negative electrode active material layer containing a negative electrode active material, a synthetic rubber adhesive and a thickener as a binder, and a current collector.

2-1. Synthetic Rubber Adhesive and Thickener The present invention is characterized in that the negative electrode active material layer contains a specific amount of a synthetic rubber adhesive and a thickener as the negative electrode active material and the binder.
<Synthetic rubber adhesive>
The synthetic rubber-based adhesive is not particularly limited as long as it is a material that is stable with respect to a non-aqueous electrolyte solution and a solvent used during electrode production.
Specific examples include styrene butadiene rubber, isoprene rubber, butadiene rubber, fluoro rubber, NBR (acrylonitrile butadiene rubber), ethylene propylene rubber, and the like. Of these, styrene butadiene rubber is preferred because of its stability in the battery system. In addition, these may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the synthetic rubber-based adhesive to 100 parts by mass of the negative electrode active material is 0.1 parts by mass or more, preferably 0.25 parts by mass, more preferably 0.5 parts by mass or more, and 0.6 parts by mass or more. More preferably, it is 5 parts by mass or less, preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and further preferably 1 part by mass or less. If the ratio of the synthetic rubber-based adhesive to the negative electrode active material exceeds the above range, the synthetic rubber-based adhesive ratio in which the amount of the synthetic rubber-based adhesive does not contribute to the battery capacity may increase, leading to a decrease in battery capacity. is there. On the other hand, below the above range, the strength of the negative electrode may be reduced.

<Thickener>
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. Among these, carboxymethyl cellulose or a salt thereof is preferable from the viewpoint of stability in the battery system. In addition, these may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the thickener to 100 parts by mass of the negative electrode active material is 0.1 parts by mass or more, preferably 0.25% by mass, more preferably 0.5 parts by mass or more, and further preferably 0.6 parts by mass or more. Moreover, it is 5 mass parts or less, 3 mass parts or less are preferable, 2 mass parts or less are more preferable, and 1 mass% or less are more preferable. When the ratio of the thickener to the negative electrode active material is within the above range, it is possible to suppress a decrease in battery capacity and an increase in resistance, and it is possible to ensure appropriate applicability.

  The blending mass ratio of the synthetic rubber adhesive and the thickener is preferably 1:99 to 99: 1, more preferably 25:75 to 75:25, and 40:60 to 60 : 400 is more preferable. When it mix | blends in this range, moderate applicability | paintability can be ensured, maintaining the moderate electrode plate intensity | strength of a negative electrode.

2-1-2. Negative electrode active material The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like. Of these, carbonaceous materials are preferred. In addition, these may be used individually by 1 type and may be used together combining 2 or more types arbitrarily.

As a carbonaceous material used as a negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C;
(3) a carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different crystallinities and / or has an interface in contact with the different crystalline carbonaceous materials,
(4) A carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different orientations and / or has an interface in contact with the carbonaceous materials having different orientations,
Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Moreover, the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.

  Examples of the artificial carbonaceous material and artificial graphite material of (2) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, those obtained by oxidizing these pitches, needle coke, pitch coke and Carbon materials that are partially graphitized, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials and their carbides, or carbonizable organic materials are benzene, toluene, xylene, quinoline And a solution dissolved in a low-molecular organic solvent such as n-hexane, and carbides thereof.

As an alloy material used as the negative electrode active material, as long as lithium can be occluded / released, lithium alone, simple metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, sulfides thereof Any of compounds such as products or phosphides may be used and is not particularly limited. The single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin (hereinafter referred to as “ Simple metals) and alloys or compounds containing these atoms (sometimes abbreviated as “specific metal elements”). These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  As a negative electrode active material having at least one kind of atom selected from a specific metal element, a metal simple substance of any one specific metal element, an alloy composed of two or more specific metal elements, one type or two or more specific types Alloys comprising metal elements and one or more other metal elements, as well as compounds containing one or more specific metal elements, and oxides, carbides, nitrides and silicides of the compounds And composite compounds such as sulfides or phosphides. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

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

  Among these negative electrode active materials, since the capacity per unit mass is large when a battery is formed, any one simple metal of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, silicon and / or tin metal simple substance, alloy, oxide, carbide, nitride and the like are preferable from the viewpoint of capacity per unit mass and environmental load.

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

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

LixTiyMzO4 (A)
[In general formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. ]
Among the compositions represented by the general formula (A),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because of a good balance of battery performance.

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

2-1-3. Physical Properties of Carbonaceous Material When using a carbonaceous material as the negative electrode active material, it is desirable to have the following physical properties.

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

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

  When the volume-based average particle size is in the above range, the loss of the initial battery capacity due to the increase in irreversible capacity can be suppressed, and uniform electrode application is possible when the electrode preparation step by application is included.

  The volume-based average particle size is measured by dispersing carbon powder in a 0.2% by weight aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This can be performed using a meter (LA-700 manufactured by Horiba, Ltd.). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

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

Further, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.

  The Raman R value and the Raman half-value width are indices indicating the crystallinity of the surface of the carbonaceous material, but the carbonaceous material has an appropriate crystallinity from the viewpoint of chemical stability, while the interlayer in which Li enters by charge / discharge. It is preferable that the crystallinity is such that it does not disappear. In the case where the density of the negative electrode is increased by press after applying to the current collector, it is preferable to take account of this because crystals tend to be oriented in a direction parallel to the electrode plate.

  When the Raman R value or the Raman half-value width is in the above range, the reaction between the carbonaceous material and the nonaqueous electrolytic solution can be suppressed, and the deterioration of the load characteristics due to the disappearance of the site can be suppressed.

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity IA of a peak PA around 1580 cm ^-1, and measuring the intensity IB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IB / IA) . The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention. Further, the half width of the peak PA near 1580 cm ⁻¹ of the obtained Raman spectrum is measured, and this is defined as the Raman half width of the carbonaceous material of the present invention.

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
· Measurement ^range: 1100cm ^-1 ~1730cm -1 · Raman R value, Raman half-value width Analysis: Background processing, smoothing processing: simple average, convolution 5 points

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

  When the value of the BET specific surface area is in the above range, precipitation of lithium on the electrode surface can be suppressed, while gas generation due to reaction with the non-aqueous electrolyte can be suppressed.

  The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure becomes 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material of the present invention.

(Roundness)
When the circularity is measured as the degree of the sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere. The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable.

  The greater the degree of circularity of the carbonaceous material, the better the filling property and the resistance between particles, so that the high current density charge / discharge characteristics are improved. Therefore, the higher the circularity is within the above range, the better.

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

  The method for improving the circularity is not particularly limited, but a sphere-shaped sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, and a mechanical / physical treatment in which a plurality of fine particles are granulated by the binder or the adhesive force of the particles themselves. Methods and the like.

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

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the carbonaceous material of the present invention.

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

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. Set the molding obtained by filling 0.47 g of the sample into a molding machine with a diameter of 17 mm and compressing it with 58.8 MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. The orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material of the present invention.

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

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

  The aspect ratio is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Carbonaceous material particles when three-dimensional observation is performed by selecting arbitrary 50 graphite particles fixed to the end face of a metal having a thickness of 50 μm or less and rotating and tilting the stage on which the sample is fixed. The longest diameter A and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained. The aspect ratio (A / B) obtained by the measurement is defined as the aspect ratio of the carbonaceous material of the present invention.

(Mixed with secondary materials)
The sub-material mixing means that two or more types of carbonaceous materials having different properties are contained in the negative electrode and / or the negative electrode active material. The properties referred to here are selected from the group consisting of X-ray diffraction parameters, median diameter, aspect ratio, BET specific surface area, orientation ratio, Raman R value, tap density, true density, pore distribution, circularity, and ash content. Shows more than one characteristic.

  As a particularly preferred example of mixing these secondary materials, the volume-based particle size distribution is not symmetrical when centered on the median diameter, containing two or more carbonaceous materials having different Raman R values, And X-ray parameters are different.

  As an example of the effect of the admixture of secondary materials, carbonaceous material such as graphite (natural graphite, artificial graphite), carbon black such as acetylene black, and amorphous carbon such as needle coke is contained as a conductive material. Reducing electrical resistance.

  When mixing a conductive material as a secondary material mixture, one type may be mixed alone, or two or more types may be mixed in any combination and ratio. The mixing ratio of the conductive material to 100 parts by mass of the carbonaceous material is usually 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, and usually 45 parts by mass. Part or less, preferably 40 parts by weight or less. When the mixing ratio is in the above range, the effect of reducing electric resistance can be secured and an increase in initial irreversible capacity can be suppressed.

2-1-4. Negative electrode The negative electrode generally comprises a current collector and a negative electrode active material layer. Any known method can be used for producing the negative electrode active material layer using the negative electrode active material, the binder (synthetic rubber adhesive), and the thickener, as long as the effects of the present invention are not significantly impaired. For example, a negative electrode active material, a binder (synthetic rubber adhesive), a solvent, a thickener, and a conductive material, a filler, etc. as necessary are added to form a slurry, which is applied to a current collector and dried. The negative electrode active material layer can be formed by pressing later.

(Current collector)
As the current collector for holding the negative electrode active material layer, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.

  In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.

  The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less, from the viewpoint of securing battery capacity and handling properties.

(Thickness ratio between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, but the value of “(the thickness of the negative electrode active material layer on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector)” However, 150 or less is preferable, 20 or less is more preferable, 10 or less is particularly preferable, 0.1 or more is preferable, 0.4 or more is more preferable, and 1 or more is particularly preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer is in the above range, battery capacity can be secured and heat generation of the current collector during high current density charge / discharge can be suppressed.

(Slurry forming solvent)
Solvents for forming the slurry are solvents that can dissolve or disperse the negative electrode active material, the binder (synthetic rubber adhesive), and the thickener and conductive material used as necessary. If there is, there is no particular limitation on the type.

  Specific examples of the slurry forming solvent include water, alcohol and the like. In addition, these solvents may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

(Electrode density)
The electrode structure when the negative electrode active material is converted into an electrode is not particularly limited, but the density of the negative electrode active material layer present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g · cm ^−3. The above is more preferable, 1.3 g · cm ⁻³ or more is particularly preferable, 2.2 g · cm ⁻³ or less is preferable, 2.1 g · cm ⁻³ or less is more preferable, and 2.0 g · cm ⁻³ or less is preferable. Is more preferable, and 1.9 g · cm ⁻³ or less is particularly preferable. If the density of the negative electrode active material layer existing on the current collector is within the above range, the negative electrode active material particles are prevented from being destroyed, and the initial irreversible capacity is increased, or the vicinity of the current collector / negative electrode active material interface While deterioration of the high current density charge / discharge characteristics due to a decrease in the permeability of the non-aqueous electrolyte to the battery can be suppressed, a decrease in battery capacity and an increase in resistance can be suppressed.

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

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. 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, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

2-2. Positive electrode <positive electrode active material>
The positive electrode active material (lithium transition metal compound) used for the positive electrode is described below.
(Lithium transition metal compounds)
A lithium transition metal compound is a compound having a structure capable of desorbing and inserting Li ions, and examples thereof include sulfides, phosphate compounds, and lithium transition metal composite oxides. Examples of sulfides include compounds having a two-dimensional layered structure such as TiS ₂ and MoS ₂ , and strong compounds represented by the general formula Me _x Mo ₆ S ₈ (Me is various transition metals including Pb, Ag, and Cu). Examples thereof include a sugar compound having a three-dimensional skeleton structure. Examples of the phosphate compound include those belonging to the olivine structure, and are generally represented by LiMePO ₄ (Me is at least one or more transition metals), specifically LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , Examples include LiMnPO ₄ . Examples of the lithium transition metal composite oxide include spinel structures capable of three-dimensional diffusion and those belonging to a layered structure capable of two-dimensional diffusion of lithium ions. Those having a spinel structure are generally expressed as LiMe ₂ O ₄ (Me is at least one transition metal), specifically, LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O. ₄ , LiCoVO _{4 and the} like. Those having a layered structure are generally expressed as LiMeO ₂ (Me is at least one transition metal). LiCoO _{2 Specifically, LiNiO 2, LiNi 1-x} Co x O 2, LiNi 1-x-y Co x Mn y O 2, LiNi 0.5 Mn 0.5 O 2, Li 1.2 Cr 0. _{4 Mn 0.4 O 2, Li 1.2} Cr 0.4 Ti 0.4 O 2, such as LiMnO ₂ and the like.

<Composition>
The lithium-containing transition metal compound is, for example, a lithium transition metal compound represented by the following composition formula (A) or (B).
1) In the case of a lithium transition metal compound represented by the following composition formula (A) Li _{1 + x} MO ₂ (A)
However, x is usually 0 or more and 0.5 or less. M is an element composed of Ni and Mn or Ni, Mn and Co, and the Mn / Ni molar ratio is usually 0.1 or more and 5 or less. The Ni / M molar ratio is usually 0 or more and 0.5 or less. The Co / M molar ratio is usually 0 or more and 0.5 or less. In addition, the rich portion of Li represented by x may be replaced with the transition metal site M.

  In the composition formula (A), the atomic ratio of the oxygen amount is described as 2 for convenience, but there may be some non-stoichiometry. Moreover, x in the said compositional formula is the preparation composition in the manufacture stage of a lithium transition metal type compound. Usually, batteries on the market are aged after the batteries are assembled. For this reason, the Li amount of the positive electrode may be deficient with charge / discharge. In this case, x may be measured to be −0.65 or more and 1 or less when discharged to 3 V in composition analysis.

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

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

2) A lithium transition metal compound represented by the following general formula (B).
_{Li [Li a M b Mn 2} -b-a] O 4 + δ ··· (B)
However, M is an element comprised from at least 1 sort (s) of the transition metals chosen from Ni, Cr, Fe, Co, Cu, Zr, Al, and Mg.
The value of b is usually 0.4 or more and 0.6 or less.
If the value of b is this range, the energy density per unit mass in a lithium transition metal type compound will be high.

  The value of a is usually 0 or more and 0.3 or less. Moreover, a in the above composition formula is a charged composition in the production stage of the lithium transition metal compound. Usually, batteries on the market are aged after the batteries are assembled. For this reason, the Li amount of the positive electrode may be deficient with charge / discharge. In this case, a may be measured to be −0.65 or more and 1 or less when discharged to 3 V in composition analysis. When the value of a is within this range, the energy density per unit mass in the lithium transition metal compound is not significantly impaired, and good load characteristics can be obtained.

Furthermore, the value of δ is usually in the range of ± 0.5.
If the value of δ is within this range, the stability as a crystal structure is high, and the cycle characteristics and high-temperature storage of a battery having an electrode produced using this lithium transition metal compound are good.
Here, the chemical meaning of the lithium composition in the lithium nickel manganese composite oxide, which is the composition of the lithium transition metal compound, will be described in more detail below.

In order to obtain a and b in the composition formula of the lithium transition metal compound, each transition metal and lithium are analyzed with an inductively coupled plasma emission spectrometer (ICP-AES) to obtain a ratio of Li / Ni / Mn. It is calculated by the thing.
From a structural point of view, it is considered that lithium related to a is substituted for the same transition metal site. Here, due to the lithium according to a, the average valence of M and manganese becomes larger than 3.5 due to the principle of charge neutrality.
Further, the lithium transition metal based compound may be substituted with fluorine, it is expressed as _{LiMn 2 O 4-x F 2x} .

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

<Introduction of foreign elements>
Moreover, a different element may be introduce | transduced into a lithium transition metal type compound. As the different elements, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Ru, Rh, Pd, Ag, In, Sb, Te , Ba, Ta, Mo, W, Re, Os, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi , N, F, S, Cl, Br, I, As, Ge, P, Pb, Sb, Si, and Sn. These foreign elements may be incorporated into the crystal structure of the lithium transition metal compound, or may not be incorporated into the crystal structure of the lithium transition metal compound, and may be a single element or compound on the particle surface or grain boundary. May be unevenly distributed.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery is formed by forming a positive electrode active material layer containing the above-described lithium transition metal compound powder for a lithium secondary battery positive electrode material and a binder on a current collector.
The positive electrode active material layer is usually formed by mixing a positive electrode material, a binder, and a conductive material and a thickener, which are used if necessary, in a dry form into a sheet shape, and then pressing the positive electrode current collector on the positive electrode current collector. Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, which is applied to the positive electrode current collector and dried.

As the material for the positive electrode current collector, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and carbon materials such as carbon cloth and carbon paper are usually used. As for the shape, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, etc. Etc. In addition, you may form a thin film suitably in mesh shape.
When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but a range of usually 1 μm or more and 100 mm or less is suitable. If it is thinner than the above range, the strength required for the current collector may be insufficient. On the other hand, if it is thicker than the above range, the handleability may be impaired.

  The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material that is stable with respect to the liquid medium used during electrode production may be used. Specific examples include polyethylene, Resin polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene・ Rubber polymers such as propylene rubber, styrene / butadiene / styrene block copolymers and hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymers), styrene / ethylene / butadiene / ethylene copolymers, Styrene / isoprene styrene bromide Copolymer and its hydrogenated thermoplastic elastomeric polymer, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Fluorine polymers such as soft resinous polymers, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers, ion conductivity of alkali metal ions (especially lithium ions) And a polymer composition having the same. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. Battery capacity and conductivity may be reduced.
The positive electrode active material layer usually contains a conductive material in order to increase conductivity. There are no particular restrictions on the type, but specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. And carbon materials. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios. The proportion of the conductive material in the positive electrode active material layer is usually 0.01% by mass or more and 50% by mass or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, and conversely if it is too high, the battery capacity may be reduced.

As a liquid medium for forming a slurry, it is possible to dissolve or disperse a lithium transition metal compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as necessary. If it is a solvent, 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 and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. be able to. In particular, when an aqueous solvent is used, a dispersant is added together with the thickener, and a slurry such as SBR is slurried. In addition, these solvents may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

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

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

2-3. Separator Normally, 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.
The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. 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 glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, 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.

  The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, 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 using a porous material such as a porous sheet or nonwoven fabric as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Further, it is usually 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.

Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, 0.2 micrometer or less is preferable, and it is 0.05 micrometer or more normally. 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 inorganic materials, 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. 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 above-described 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.

  The characteristics of the separator in the non-electrolyte secondary battery can be grasped by the Gurley value. The Gurley value indicates the difficulty of air passage in the film thickness direction, and is expressed as the number of seconds required for 100 ml of air to pass through the film. It means that it is harder to go through. That is, a smaller value means better communication in the thickness direction of the film, and a larger value means lower communication in the thickness direction of the film. Communication is the degree of connection of holes in the film thickness direction. If the Gurley value of the separator of the present invention is low, it can be used for various purposes. For example, when used as a separator for a non-aqueous lithium secondary battery, a low Gurley value means that lithium ions can be easily transferred and is preferable because of excellent battery performance. Although the Gurley value of a separator is arbitrary, Preferably it is 10-1000 second / 100ml, More preferably, it is 15-800 second / 100ml, More preferably, it is 20-500 second / 100ml. If the Gurley value is 1000 seconds / 100 ml or less, the electrical resistance is substantially low, which is preferable as a separator.

2-4. Battery design <electrode group>
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed through the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape through the separator. Either is acceptable. 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, preferably 80% or less. .

  When the electrode group occupancy is below the above range, the battery capacity decreases. In addition, if the above range is exceeded, there is less void space, the battery expands, and the member expands or the vapor pressure of the liquid component of the electrolyte increases and the internal pressure rises, and the charge / discharge cycle performance as a battery 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.

<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, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

  In an exterior case using metals, the metal is welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed sealed structure, or a caulking structure using the above metals via a resin gasket. Things. Examples of the outer case using the laminate film include a case where a resin-sealed structure is formed by heat-sealing resin layers. In order to improve 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>
Protection elements such as PTC (Positive Temperature Coefficient), thermal fuse, thermistor, which increases resistance when abnormal heat is generated or excessive current flows, shuts off current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature during abnormal heat generation A valve (current cutoff valve) or the like can be used. It is preferable to select a protective element that does not operate under normal use at a high current, and it is more preferable that the protective element is designed 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. This exterior body is not particularly limited, and any known one can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, 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, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
The compound represented by the general formula (1) used in this example is shown below.

1,3-bis (isocyanatomethyl) cyclohexane: Compound (i)

2,2,4-trimethylhexamethylene diisocyanate: Compound (ii)

2,4,4-trimethylhexamethylene diisocyanate: Compound (iii)
Moreover, the compound used for the comparative example is shown below.

Hexamethylene diisocyanate: Compound (iv)

<Example 1-1 and Comparative Examples 1-1 to 1-2 (Battery evaluation)>
[Example 1-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, ethylene carbonate (hereinafter may be referred to as EC), monofluoroethylene carbonate (hereinafter may be referred to as MFEC), dimethyl carbonate (hereinafter may be referred to as DMC) and vinylene carbonate (hereinafter referred to as EC). , Which may be referred to as VC) (volume ratio 15: 15: 70: 1), 0.5% by mass of compound (iv) and 0.5% by mass of adiponitrile as the content in the non-aqueous electrolyte Next, LiPF ₆ which was mixed and sufficiently dried was dissolved at a ratio of 1.0 mol / liter to prepare a basic electrolyte. Compound (i) 0.5 mass% was mixed with this basic electrolyte solution as content in a non-aqueous electrolyte solution, and electrolyte solution was prepared.

[Production of negative electrode]
Aqueous dispersion of sodium carboxymethylcellulose (hereinafter sometimes referred to as CMC) as a thickener and binder as 100 parts by mass of natural graphite powder as the negative electrode active material (concentration of 1% by mass of carboxymethylcellulose sodium), Then, an aqueous dispersion of styrene butadiene rubber (hereinafter sometimes referred to as SBR) (concentration of styrene butadiene rubber of 50% by mass) was added and mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become a mass ratio of natural graphite: SBR: CMC = 100: 1: 1.

[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 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied to both sides of a 21 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

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

[Initial capacity evaluation]
A non-aqueous electrolyte secondary battery is charged with being sandwiched between glass plates and pressurized at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then at a constant current up to 3.0 V at 0.2 C. Discharge was performed. After that, constant current-constant voltage charge (hereinafter referred to as “CC-CV charge” where appropriate) (0.05C cut) to 4.1V with a current corresponding to 0.2C, and then discharged to 3V with a constant current of 0.2C. did. Furthermore, after CC-CV charge (0.05C cut) to 4.33V with a current corresponding to 0.2C, the operation of discharging to 3V at 0.2C was repeated three times, and the third discharge capacity was set as the initial capacity. . Furthermore, after CCCV charge (0.05C cut) to 4.33V at 0.2C, discharge again to 3V at 0.5C to obtain the initial 0.5C discharge capacity, and the ratio of the initial 0.5C discharge capacity to the initial capacity This was determined as the initial rate characteristic (%).
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage characteristics evaluation]
After the initial capacity evaluation, the non-aqueous electrolyte secondary battery was CCCV charged (cut at 0.05 C) to 4.33 V at 0.2 C at 25 ° C., and then at 85 ° C. for 24 hours. High temperature storage was performed. After fully cooling the battery, discharge to 3V at 0.2C at 25 ° C, then charge CCCV (0.05C cut) to 4.33V at 0.2C, discharge to 3V at 0.2C, and high temperature The 0.2C discharge capacity after storage characteristic evaluation was calculated | required and this was made into the capacity | capacitance after storage. Further, after CCCV charge (0.05C cut) to 4.33V at 0.2C, discharge to 3V again at 0.5C to obtain 0.5C discharge capacity after evaluation of high-temperature storage characteristics, and storage at high temperature relative to post-storage capacity The ratio of 0.5 C discharge capacity after the characteristic evaluation was determined, and this was defined as the rate characteristic (%) after storage.
Using the non-aqueous electrolyte secondary battery produced above, initial capacity evaluation and high-temperature storage characteristic evaluation were performed. The evaluation results are shown in Table 1.

[Comparative Example 1-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1, except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Example 1-1. Characterization was performed. The evaluation results are shown in Table 1.

[Comparative Example 1-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that 0.5% by mass of compound (iv) was used in place of compound (i) in the electrolyte solution of Example 1-1. Initial capacity evaluation and high temperature storage characteristics evaluation were performed. The evaluation results are shown in Table 1. In addition, the total content of compound (iv) in the electrolytic solution of Comparative Example 1-2 is 1% by mass.

From Table 1, when the non-aqueous electrolyte solution of Example 1-1 according to the present invention is used, compared with the case where the compound represented by the general formula (1) is not added (Comparative Example 1-1), the initial capacity and It can be seen that the initial rate characteristics are almost the same, and the capacity after storage and the rate characteristics after storage are excellent.
On the other hand, when the compound (iv) not included in the range of the general formula (1) is used (Comparative Example 1-2), although the improvement effect is seen in the capacity after storage and the rate characteristics after storage, the general formula (1) It is inferior to the case where the compound shown by is added. Further, it can be seen that the addition of compound (iv) is insufficient as an additive because the initial capacity and the initial rate characteristics are lowered. This decrease is thought to be due to an increase in overvoltage during charging / discharging due to the high-resistance film formed on the negative electrode by adding compound (iv).

<Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-11 (Battery evaluation)>
[Example 2-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, MFEC 4.7 mass as a content in a non-aqueous electrolyte solution in a mixture (volume ratio 30:30:40) of EC, DMC and ethyl methyl carbonate (hereinafter sometimes referred to as EMC) % And 0.5% by mass of compound (i) were mixed, and then sufficiently dried LiPF ₆ was dissolved at a rate of 1.0 mol / liter to prepare an electrolytic solution.

[Production of negative electrode]
Aqueous dispersion of sodium carboxymethylcellulose (concentration of 1% by weight of carboxymethylcellulose sodium) and aqueous styrene-butadiene rubber as thickener and binder, respectively, on 100 parts by mass of amorphous coated natural graphite powder as negative electrode active material A predetermined amount of dispersion (concentration of styrene butadiene rubber 50% by mass) was added and mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become a mass ratio of amorphous covering natural graphite: SBR: CMC = 100: 0.5: 1.

[Production of positive electrode]
Using 90 parts by mass of lithium nickel manganese cobaltate (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) as the positive electrode active material, 7 parts by mass of carbon black as the conductive material, and 3 parts by mass of polyvinylidene fluoride as the binder The parts were mixed, N-methyl-2-pyrrolidone was added to form a slurry, which was uniformly applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to obtain a positive electrode.

[Production of secondary battery (coin type)]
Using the positive electrode, the negative electrode, and the nonaqueous electrolytic solution, a coin-type cell was manufactured according to the following procedure. That is, the positive electrode was housed in a stainless steel can that also serves as the positive electrode conductor, and the negative electrode was placed thereon via a polyethylene separator impregnated with an electrolyte solution described later. The can body and a sealing plate serving also as a negative electrode conductor were caulked and sealed through an insulating gasket to produce a non-aqueous electrolyte battery (coin type).

[Initial capacity evaluation]
The fabricated secondary battery (coin type) was CC charged for 6 hours at 25 ° C. with a current corresponding to 0.05 C, and then CC discharged to 0.2 V at 0.2 C. Then, CC-CV charge (0.05C cut) was carried out to 4.1V with the electric current equivalent to 0.2C, and CC discharge was carried out to 3V with the constant current of 0.2C. Furthermore, after CC-CV charge (0.05 C cut) to 4.2 V with a current corresponding to 0.2 C, the operation of CC discharge to 3 V at 0.2 C is repeated three times, and the third discharge capacity is defined as the initial capacity. did.

[High temperature storage characteristics evaluation (coin type)]
After the initial capacity evaluation, the non-aqueous electrolyte secondary battery was CCCV charged at 0.2C to 4.2V at 0.2C (0.05C cut), and then at 80 ° C for 24 hours. High temperature storage was performed. After fully cooling the battery, discharge to 3V at 0.2C at 25 ° C, then charge CCCV to 0.2V at 0.2C (0.05C cut), discharge to 3V at 0.2C, and high temperature The 0.2C discharge capacity after storage characteristic evaluation was calculated | required and this was made into the capacity | capacitance after storage.
Using the produced non-aqueous electrolyte secondary battery, initial capacity evaluation and high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Example 2-2]
In Example 2-1, instead of the negative electrode having a mass ratio of amorphous coated natural graphite: SBR: CMC = 100: 0.5: 1, amorphous coated natural graphite: SBR: CMC = 100: 1: 1 A non-aqueous electrolyte battery was produced in the same manner as in Example 2-1, except that a negative electrode having a mass ratio of 1 was used, and an initial capacity evaluation and a high temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Example 2-3]
In Example 2-1, amorphous coated natural graphite: SBR: CMC = 100: 2: 2 instead of the negative electrode having a mass ratio of amorphous coated natural graphite: SBR: CMC = 100: 0.5: 1 A non-aqueous electrolyte battery was produced in the same manner as in Example 2-1, except that a negative electrode having a mass ratio of 1 was used, and an initial capacity evaluation and a high temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Example 2-4]
In Example 2-1, instead of the negative electrode having a mass ratio of amorphous coated natural graphite: SBR: CMC = 100: 0.5: 1, amorphous coated natural graphite: SBR: CMC = 100: 3: 2 A non-aqueous electrolyte battery was prepared in the same manner as in Example 2-1, except that a negative electrode having a mass ratio of 1 was used, and an initial capacity evaluation and a high temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Comparative Example 2-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-1, except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Example 2-1. Characteristic evaluation (coin type) was conducted. The evaluation results are shown in Table 2.

[Comparative Example 2-2]
In the electrolyte solution of Example 2-1, the non-aqueous electrolyte solution 2 was used in the same manner as in Example 2-1, except that 0.5% by mass of the compound (iv) was used instead of 0.5% by mass of the compound (i). A secondary battery was prepared, and an initial capacity evaluation and a high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Comparative Example 2-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-2 except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Example 2-2. Characteristic evaluation (coin type) was conducted. The evaluation results are shown in Table 2.

[Comparative Example 2-4]
In the electrolytic solution of Example 2-2, the non-aqueous electrolytic solution 2 was prepared in the same manner as in Example 2-2 except that 0.5% by mass of the compound (iv) was used instead of 0.5% by mass of the compound (i). A secondary battery was prepared, and an initial capacity evaluation and a high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Comparative Example 2-5]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-3, except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Example 2-3. Characteristic evaluation (coin type) was conducted. The evaluation results are shown in Table 2.

[Comparative Example 2-6]
In the electrolytic solution of Example 2-3, non-aqueous electrolytic solution 2 was prepared in the same manner as in Example 2-3 except that 0.5% by mass of compound (iv) was used instead of 0.5% by mass of compound (i). A secondary battery was prepared, and an initial capacity evaluation and a high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Comparative Example 2-7]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 2-4 except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Example 2-4. Characteristic evaluation (coin type) was conducted. The evaluation results are shown in Table 2.

[Comparative Example 2-8]
In the electrolyte solution of Example 2-4, non-aqueous electrolyte solution 2 was prepared in the same manner as in Example 2-4 except that 0.5% by mass of compound (iv) was used instead of 0.5% by mass of compound (i). A secondary battery was prepared, and an initial capacity evaluation and a high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

[Comparative Example 2-9]
In Example 2-1, instead of the negative electrode having a mass ratio of amorphous coated natural graphite: SBR: CMC = 100: 0.5: 1, an organic negative electrode prepared by the following procedure was used. A non-aqueous electrolyte battery was prepared in the same manner as in 2-1, and initial capacity evaluation and high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

<Preparation of organic negative electrode>
93 parts by weight of graphite powder as a negative electrode active material, 1 part by weight of carbon black as a conductive agent, and 6 parts by weight of PVdF as a binder were added, and N-methylpyrrolidone was added to form a slurry. After uniformly applying and drying to a current collector made of copper having a thickness of 12 μm, roll pressing was performed to obtain an organic negative electrode.

[Comparative Example 2-10]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Comparative Example 2-9, except that the electrolyte solution containing no compound (i) was used in the electrolyte solution of Comparative Example 2-9. Characteristic evaluation (coin type) was conducted. The evaluation results are shown in Table 2.

[Comparative Example 2-11]
In the electrolytic solution of Comparative Example 2-9, a non-aqueous electrolytic solution 2 was prepared in the same manner as in Comparative Example 2-9, except that 0.5% by mass of compound (iv) was used instead of 0.5% by mass of compound (i). A secondary battery was prepared, and an initial capacity evaluation and a high-temperature storage characteristic evaluation (coin type) were performed. The evaluation results are shown in Table 2.

From Table 2, when the non-aqueous electrolyte solution of Examples 2-1 to 2-4 according to the present invention is used, the compound represented by the general formula (1) is not added (Comparative Examples 2-1 and 2- 3 and 2-5, 2-7), it can be seen that the initial capacity and the capacity after storage are excellent.
On the other hand, when the compound (iv) not included in the range of the general formula (1) is used (Comparative Examples 2-2, 2-4, 2-6, 2-8), the initial capacity and the capacity after storage are improved. However, since it is inferior to the case where the compound represented by the general formula (1) is added in almost all systems, it can be seen that it is insufficient as an additive. The difference in the effects of the compound represented by the general formula (1) and the compound not included in the range of the general formula (1) was most remarkable in Example 2-2 and Example 2-3.
Furthermore, when a negative electrode not included in the present invention was used (Comparative Examples 2-9 to 2-11), the effect of improving the initial capacity and the capacity after storage was observed by adding the compound represented by the general formula (1). Although it is inferior to the case where the compound (iv) not included in the range of the general formula (1) is used, it is understood that the battery characteristics are insufficient.

<Example 3-1 and Comparative Examples 3-1 to 3-2 (Battery Evaluation)>
[Example 3-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, a mixture of EC, MFEC, DMC and VC (volume ratio 15: 15: 70: 1) was mixed with 2,2,4-trimethylhexamethylene diisocyanate (hereinafter referred to as “content” in the non-aqueous electrolyte). 0.15% by mass (sometimes referred to as compound (ii)) and 0.15% by mass 2,4,4-trimethylhexamethylene diisocyanate (hereinafter sometimes referred to as compound (iii)) were mixed, and then sufficient The electrolyte solution was prepared by dissolving LiPF ₆ dried in a ratio of 1.0 mol / liter.

[Production of positive electrode]
It produced similarly to Example 1-1.

[Production of negative electrode]
It produced similarly to Example 1-1.

[Production of secondary battery]
It produced similarly to Example 1-1.

[Initial capacity evaluation]
In a state where a non-aqueous electrolyte battery is pressed between glass plates and pressed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, the battery is discharged at a constant current up to 3.0 V at 0.2 C. went. Then, CC-CV charge (0.05C cut) was carried out to 4.1V with the electric current equivalent to 0.2C, and it was left to stand on 45 degreeC and the conditions for 72 hours. Then, it discharged to 3V with a constant current of 0.2C. Furthermore, after CC-CV charge (0.05C cut) to 4.33V with a current corresponding to 0.2C, the operation of discharging to 3V at 0.2C was repeated three times, and the discharge capacity for the third time was initially 0.2C. The capacity. Further, after CCCV charge (0.05C cut) to 4.33V at 0.2C, discharge again to 3V at 0.5C to obtain the initial 0.5C discharge capacity, and the initial 0.5C discharge with respect to the initial 0.2C capacity The ratio of the capacity was determined and used as the initial rate characteristic (%).

[High temperature storage characteristics evaluation]
After the initial capacity evaluation, the non-aqueous electrolyte battery was CCCV charged (0.05 C cut) at 25 ° C. to 4.33 V at 0.2 C, and then stored at 85 ° C. for 24 hours at a high temperature. Went. After sufficiently cooling the battery, the battery was discharged at 25 ° C. to 3 V at 0.2 C, and the remaining capacity after high-temperature storage characteristics evaluation was determined. This was defined as the remaining capacity. Again, perform CCCV charge (0.05C cut) to 4.33V at 0.2C, discharge to 3V at 0.2C, obtain 0.2C discharge capacity after high temperature storage characteristics evaluation, recover this 0.2C capacity It was. Furthermore, after CCCV charge (0.05C cut) to 4.33V at 0.2C, discharge again to 3V at 0.5C to obtain 0.5C discharge capacity after high temperature storage characteristics evaluation, and with respect to recovery 0.2C capacity The ratio of 0.5 C discharge capacity after high temperature storage characteristic evaluation was calculated | required, and this was made into the rate characteristic (%) after storage.
Using the non-aqueous electrolyte battery produced above, initial capacity evaluation and high-temperature storage characteristic evaluation were performed. The evaluation results are shown in Table 3.

[Comparative Example 3-1]
A non-aqueous electrolyte battery was produced in the same manner as in Example 3-1, except that the electrolyte solution containing no compound (ii) and compound (iii) was used in the electrolyte solution of Example 3-1, and initial capacity evaluation was performed. In addition, high temperature storage characteristics were evaluated. The evaluation results are shown in Table 3.

[Comparative Example 3-2]
A nonaqueous electrolyte battery in the same manner as in Example 3-1, except that 0.3% by mass of the compound (iv) was used in place of the compound (ii) and the compound (iii) in the electrolyte of Example 3-1. The initial capacity and high temperature storage characteristics were evaluated. The evaluation results are shown in Table 3.

From Table 3, when the nonaqueous electrolyte solution of Example 3-1 according to the present invention is used, the initial rate characteristics are compared with the case where the compound represented by the general formula (1) is not added (Comparative Example 3-1). Are equivalent and have excellent initial 0.2C capacity, residual capacity, recovery 0.2C capacity and post-storage rate characteristics.
On the other hand, when the compound (iv) not included in the range of the general formula (1) is used (Comparative Example 3-2), although the initial 0.2C capacity, the remaining capacity, and the recovery 0.2C capacity are improved, The rate characteristics after storage are inferior to those in the case where the compound represented by the general formula (1) is added. In addition, it can be seen that the addition of compound (iv) decreases the initial rate characteristics and is insufficient as an additive. This decrease is thought to be due to an increase in overvoltage during charging / discharging due to the high-resistance film formed on the negative electrode by adding compound (iv).

According to the non-aqueous electrolyte solution of the present invention, it is possible to improve the capacity deterioration of the non-aqueous electrolyte secondary battery during high temperature storage and the charge / discharge characteristics under a high current density. Therefore, the non-aqueous electrolyte solution of the present invention and the non-aqueous electrolyte secondary battery using the same can be used for various known applications.
Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, etc. , Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Backup Power Supply, Motor, Automobile, Motorcycle, Motorbike, Bicycle, Lighting Equipment, Toy, Game Equipment, Clock, Electric Tool, Strobe, Camera, Load Examples include leveling power sources and natural energy storage power sources.

Claims (7)

In a non-aqueous electrolyte secondary battery comprising at least a positive electrode and a negative electrode capable of occluding and releasing metal ions, a separator, and a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent,
(A) The negative electrode contains a synthetic rubber adhesive and a thickener as a negative electrode active material and a binder, and the ratio of the synthetic rubber adhesive to 100 parts by mass of the negative electrode active material is 0.1 parts by mass or more. 5 parts by weight or less, and the ratio of the thickener to 100 parts by weight of the negative electrode active material has a negative electrode active material layer of 0.1 parts by weight or more and 5 parts by weight or less,
(B) The non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte includes at least one compound represented by the following general formula (1).
In (formula (1), X is a hydrocarbon group der tertiary or quaternary carbon number of 4 to 10 having at least one carbon atom is, hydrocarbon group optionally having substituent (It may have a cyclic hydrocarbon group having 4 to 6 carbon atoms . N represents an integer of 2 to 4.)   The X in the general formula (1) has a hydrocarbon group having 1 to 5 carbon atoms as a substituent adjacent to the tertiary or quaternary carbon atom. Non-aqueous electrolyte secondary battery. The synthetic rubber-based adhesive, a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that a styrene-butadiene rubber. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3 , wherein the thickener is carboxymethyl cellulose or a salt thereof. The non-aqueous system according to any one of claims 1 to 4 , wherein the compound represented by the general formula (1) is contained in a non-aqueous electrolyte solution in an amount of 0.001% by mass to 10% by mass. Electrolyte secondary battery. The non-aqueous electrolyte is a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, a difluorophosphate, an isocyanate compound other than the general formula (1), a cyclic sulfonate ester The non-aqueous electrolyte secondary battery according to any one of claims 1 to 5 , comprising at least one compound selected from the group consisting of cyano compounds. The cyclic carbonate having a fluorine atom is at least one compound selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate;
The cyclic carbonate having a carbon-carbon unsaturated bond is at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate;
The isocyanate compound other than the general formula (1) is a compound other than the general formula (1) having at least two isocyanate groups, and the cyano compound is a compound having at least two cyano groups. 6. A non-aqueous electrolyte secondary battery according to 6.