JP2013038000A - Nonaqueous electrolytic solution, and nonaqueous electrolyte battery - Google Patents

Abstract

（ＸとＺはＣＲ^１ _２、Ｃ＝Ｏ、Ｃ＝Ｎ−Ｒ^１、Ｃ＝Ｐ−Ｒ^１、Ｏ、Ｓ、Ｎ−Ｒ等を表す）
【選択図】なし[PROBLEMS] To improve durability characteristics such as cycle and storage while improving protection characteristics at the time of overcharge.
A non-aqueous electrolyte solution containing a lithium salt and a non-aqueous solvent, wherein the non-aqueous electrolyte solution includes a compound represented by the general formula (1) and a compound represented by the general formula (2). Containing.

(X and Z represent CR ¹ ₂ , C═O, C═N—R ¹ , C═P—R ¹ , O, S, N—R, etc.)
[Selection figure] None

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte battery, and more particularly to a non-aqueous electrolyte containing a specific cyclic compound having a triple bond and a specific aromatic compound, and a non-aqueous electrolyte battery.

  Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are widely used as power sources for so-called portable electronic devices such as mobile phones and notebook computers, to in-vehicle power sources for automobiles and large power sources for stationary applications. It is being put into practical use. However, with the recent high performance of electronic devices and the application to in-vehicle power supplies for driving and large power supplies for stationary applications, the demand for applied secondary batteries is increasing, and the high performance of the battery characteristics of secondary batteries is increasing. For example, it is required to achieve high levels of improvement in capacity, high temperature storage characteristics, cycle characteristics, and the like.

  The electrolyte used for the non-aqueous electrolyte lithium secondary battery is usually composed mainly of an electrolyte and a non-aqueous solvent. The main components of the nonaqueous solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone. It is used.

In order to improve battery characteristics such as load characteristics, cycle characteristics, storage characteristics, and low temperature characteristics of batteries using these non-aqueous electrolytes, and to improve battery protection characteristics during overcharge, Water solvents, electrolytes, auxiliaries and the like have also been proposed.
For example, by containing vinylene carbonate and its derivatives or vinyl ethylene carbonate compound in the electrolytic solution, a cyclic carbonate having a double bond reacts preferentially with the negative electrode to form a good film on the surface of the negative electrode. Patent Documents 1 and 2 disclose that the storage characteristics and cycle characteristics of the battery are improved.

  Patent Document 3 proposes to protect the battery by increasing the internal resistance of the battery by mixing an additive that polymerizes at a battery voltage higher than the maximum operating voltage of the battery in the electrolyte. Reference 4 describes an internal electrical disconnection device provided for overcharge protection by mixing an additive that generates gas and pressure by polymerizing in an electrolyte at a battery voltage equal to or higher than the maximum operating voltage of the battery. It has been proposed to operate reliably. Moreover, aromatic compounds, such as biphenyl, thiophene, and furan, are disclosed as those additives.

Furthermore, Patent Document 5 discloses a non-aqueous system in which phenylcyclohexane is added in a range of 0.1 to 20% by weight in a non-aqueous electrolyte solution in order to suppress deterioration of battery characteristics when biphenyl or thiophene is used. A non-aqueous electrolyte secondary battery system including an electrolyte secondary battery and a charge control system that senses an increase in battery temperature and disconnects a charging circuit has been proposed.
On the other hand, Patent Document 6 improves the affinity of the electrolyte solution with the carbon electrode by using an organic solvent selected from carbonates having a phenyl group such as methylphenyl carbonate, esters, and ethers. It is proposing to reduce the size, performance and productivity of ion batteries.

JP-A-8-45545 JP 2001-6729 A JP-A-9-106835 JP-A-9-171840 JP 2002-50398 A JP-A-8-293323

  As the demand for higher performance of secondary batteries in recent years has increased, as described above, improvements in lithium secondary battery characteristics, that is, higher capacity, higher temperature storage characteristics, cycle characteristics, etc. There is a need for improved battery protection properties. In such a background, in the nonaqueous electrolyte battery using the electrolyte solution described in Patent Documents 1 and 2, if the charged battery is left at a high temperature or a continuous charge / discharge cycle is performed, There was a problem in that the amount of gas generation increased due to the oxidative decomposition of the cyclic carbonate having a double bond in the above. When the amount of gas generation increases in such a use environment, the battery itself may become unusable due to, for example, activation of a battery safety valve or expansion of the battery.

  In addition, the oxidative decomposition of a cyclic carbonate having a double bond on the positive electrode also causes a problem of generation of a solid decomposition product in addition to an increase in gas generation. The generation of such a solid decomposition product may cause clogging of the positive electrode layer and the separator to inhibit the movement of lithium ions, or may remain on the surface of the positive electrode active material to inhibit the lithium ion insertion / release reaction. . Under such conditions, for example, the charge / discharge capacity gradually decreases during a continuous charge / discharge cycle, the charge / discharge capacity decreases after the high temperature storage or the continuous charge / discharge cycle, or the load characteristics deteriorate. There is a case.

Further, the oxidative decomposition of the cyclic carbonate having a double bond on these positive electrodes becomes a particularly serious problem under the recent high performance secondary battery design. For example, when the battery voltage at the time of full charge that is currently on the market is operated at a higher voltage than a battery of 4.2 V, these oxidation reactions are particularly prominent.
As another method for increasing the capacity of non-aqueous electrolyte batteries, it has been studied to pack as many active materials as possible in a limited battery volume. In this way, the active material layer of the electrode is pressurized. In a battery designed to increase the density and reduce the volume other than the active material in the battery as much as possible, the voids inside the battery are reduced, and the internal pressure of the battery increases significantly even when a small amount of gas is generated by oxidative decomposition. In some cases, the battery itself becomes unusable due to the operation of the safety valve or the expansion of the battery.

  Furthermore, when the aromatic compounds described in Patent Documents 3 to 6 are contained in the non-aqueous electrolyte solution, they are effective in improving the protective properties of the battery during overcharge, but these compounds have a low oxidation potential. In addition, even when stored at high temperatures, it reacts at sites with high activity of the electrode, and when these compounds react, the internal resistance of the battery is greatly increased or the discharge characteristics after storage at high temperatures are reduced by gas generation. There was a problem.

  Therefore, the present invention solves the above-mentioned various problems that are manifested in performance requirements for secondary batteries in recent years, and in particular, has improved durability characteristics such as cycling and storage while enhancing the protection characteristics of the battery during overcharge. An object is to provide an improved non-aqueous electrolyte and a non-aqueous electrolyte battery using the same.

As a result of intensive studies to solve the above-mentioned problems, the inventors have found that the compound represented by the following general formula (1) and the following general formula (1) are contained in the non-aqueous electrolyte solution used in the non-aqueous electrolyte battery. It has been found that by containing the compound represented by 2), a non-aqueous electrolyte battery having improved durability characteristics such as cycle and storage can be realized while enhancing the protection characteristics of the battery during overcharge. It came to complete.

That is, the gist of the present invention is as follows.
a) A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, wherein the non-aqueous electrolyte solution is a compound represented by the following general formula (1) and the following general formula (2): The present invention relates to a non-aqueous electrolytic solution characterized by containing a compound represented by:

(In the formula (1), X and Z represent CR ¹ ₂ , C═O, C═N—R ¹ , C═P—R ¹ , O, S, N—R ¹ , P—R ^{1 and} are the same. However, Y represents CR ¹ ₂ , C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ where , R and R ¹ are hydrogen, halogen, or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, and R ² represents a functional group. .R ³ from carbon atoms 1 also a hydrocarbon group of 20 has the, Li, ^NR _{4 4,} or a hydrocarbon group having carbon atoms 1 may have a functional group 20 .R ⁴ Is a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, n and m each represents an integer of 0 or more, and W represents the above R. .

In formula (2), R ^{5 to} R ¹⁰ may each independently have a hydrogen atom, a halogen atom, a C 1-12 hydrocarbon group that may have a halogen atom, or a halogen atom. It represents either an ether group or an ester group optionally having a halogen atom. )
b) The non-aqueous electrolyte solution according to a), wherein the compound represented by the general formula (1) is a compound represented by the formula (3).

(Y represents C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ , where R ² may have a functional group. A hydrocarbon group having 1 to 20. R ³ is Li, NR ⁴ ₄ or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and R ⁴ has a functional group. And may be the same or different from each other.
c) In the compound represented by the general formula (2), in formula (2), R ^{5 to} R ¹⁰ each independently have a hydrogen atom, a halogen atom, or a halogen atom, The nonaqueous electrolytic solution according to a) or b), which is a compound having 12 hydrocarbon groups.

d) The non-aqueous electrolyte solution according to any one of a) to c), wherein the non-aqueous electrolyte solution further contains a cyclic carbonate having a carbon-carbon double bond.
e) A non-aqueous electrolyte battery comprising a non-aqueous electrolyte solution containing a lithium salt and a non-aqueous solvent for dissolving the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a positive electrode, the non-aqueous electrolyte solution Is a non-aqueous electrolyte solution according to any one of a) to d).

  The present invention is characterized in that a compound in which a triple bond is bonded to a ring structure by a single bond without intervening other functional groups or hetero elements and a specific aromatic compound are used in a non-aqueous electrolyte battery. Usually, as typified by Patent Documents 1 and 2, many of the materials that protect the electrode surface and improve battery durability such as storage characteristics and cycle characteristics are compounds of a cyclic structure, and further have multiple bonding sites. Have. The present inventors paid attention to this point, and examined in detail the bonding sites of functional groups and heteroelements in the ring structure, the sites where multiple bonds are bonded to the ring structure, and the hybrid state of the electron orbits of the multiple bonds. As a result, for example, a compound in which a double bond is bonded to a ring structure is more stable with a positive electrode than a compound in which a part of the ring skeleton constituting the cyclic compound is a double bond, In addition, when the triple bond substituent is bonded to the ring structure, an effect superior to the durability can be obtained compared to the double bond, and even when a specific aromatic compound is contained, it is stored at high temperature. In some cases, a specific cyclic compound having a triple bond suppresses a side reaction of a specific aromatic compound on the positive electrode, and it has been found that the above problems can be solved.

  That is, by using the present invention in this way, particularly in the design of a lithium secondary battery with a high voltage and a high capacity, the durability of the battery, such as cycle and storage, is improved while enhancing the protection characteristics of the battery during overcharge. Provided are a non-aqueous electrolyte battery having improved characteristics and a non-aqueous electrolyte used for the non-aqueous electrolyte battery.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments, and can be arbitrarily modified and implemented.
1. Non-aqueous electrolyte 1-1. 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 fluorophosphates such as LiPO ₃ F, LiPO ₂ F ₂ ; tungstic acids such as LiWOF ₅ Lithium: HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CO ₂ Li, CF ₃ CF ₂
Carboxylic acid lithium salts such as CF ₂ CF ₂ CO ₂ Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, Sulfonic acid lithium salts such as 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 SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3 - perfluoropropane _{disulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2) lithium imide salts such as; LiC ( _{SO 2) 3, LiC (CF} 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3 , etc. Richiumumechido salts; lithium difluoro oxalatoborate, lithium oxalatoborate salts such as lithium bis (oxalato) borate, lithium Lithium oxalate phosphate salts such as tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate; other, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) _{2 , LiBF 2 (C 2 F 5} ) 2, Li _{F 2 (CF 3 SO 2)} 2, LiBF 2 fluorine-containing organic lithium salts _{(C 2 F 5 SO 2)} 2 and the like;
Etc.

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , LiPO ₂ F ₂ , 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 bis (oxalato) borate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, _{LiBF 3 CF 3, LiBF 3 C} 2 F _{, LiPF 3 (CF 3) 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.

  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 usually 0.3 mol / L or more, preferably 0.4 mol / L or more, more preferably 0.5 mol / L or more, and usually 3 mol. / L or less, preferably 2.5 mol / L or less, more preferably 2.0 mol / L or less. When the total molar concentration of lithium is within the above range, the electric conductivity of the electrolytic solution is sufficient, and on the other hand, a decrease in electric conductivity and a decrease in battery performance due to an increase in viscosity are prevented.

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 kinds in combination is a combination of LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F _2, etc., and has an effect of improving load characteristics and cycle characteristics. . Among these, the combined use of LiPF ₆ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F ₂ is preferable because the effect is remarkable, and among them, the combined use of LiPF ₆ and LiPO ₂ F ₂ is a remarkable effect with a small amount of addition. Is particularly preferred because

When LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li are used in combination, the ratio of LiBF ₄ or FSO ₃ Li with respect to 100% by mass of the entire non-aqueous electrolyte is not limited, and is optional as long as the effects of the present invention are not significantly impaired. However, with respect to the non-aqueous electrolyte solution of the present invention, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, while the upper limit is usually 10% by mass or less, preferably 5% by mass or less. More preferably, it is 3 mass% or less. On the other hand, LiPF ₆ and Li
Even in the case of combined use of PO ₂ F ₂ , the ratio of LiPO ₂ F ₂ with respect to 100% by mass of the entire non-aqueous electrolyte solution is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. It is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and the upper limit thereof is usually 5% by mass or less, preferably 3% by mass with respect to the liquid. Hereinafter, it is more preferably 2% by mass or less. By being in the above range, the effect of improving output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature characteristics, etc. is great. Further, it prevents the deterioration of battery characteristics due to the precipitation at low temperature and the decrease in the improvement effect such as the low temperature characteristics, cycle characteristics, and high temperature storage characteristics.

Here, the active material prepared in the electrolyte solution in the case of incorporating the LiPO ₂ F ₂ in the electrolyte solution, the LiPO ₂ F ₂ which is separately synthesized by a known method, described later method or be added to the electrolytic solution containing LiPF ₆ In the present invention, there is a method of generating LiPO ₂ F ₂ in the system when water is allowed to coexist in a battery component such as an electrode plate or the like, and a battery is assembled using an electrolyte containing LiPF _6. Any method may be used.

The method for measuring the content of LiPO ₂ F ₂ in the non-aqueous electrolyte and the non-aqueous electrolyte battery is not particularly limited, and any known method can be used. Examples include ion chromatography and F nuclear magnetic resonance spectroscopy (hereinafter sometimes abbreviated as NMR).
In addition, another preferable example in the case of using two or more kinds in combination is a combination of an inorganic lithium salt and a salt selected from lithium imide salts, lithium oxalate borate salts, and lithium oxalatophosphate salts. The combined use has an effect of suppressing deterioration due to high temperature storage. As the inorganic lithium salt, LiPF ₆ and LiBF ₄ are preferable. Examples of the salt selected from lithium imide salts, lithium oxalatoborate salts, and lithium oxalatophosphate salts include LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), and LiN (CF ₃ SO ₂ ) _2. , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethane disulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, lithium bis (oxalato) borate, lithium difluorooxalatoborate Lithium tetrafluorooxalato phosphate and lithium difluorobis (oxalato) phosphate are preferred. In this case, the ratio of the salt selected from lithium imide salts, lithium oxalatoborate salts, and lithium oxalatophosphate salts with respect to 100% by mass of the whole non-aqueous electrolyte is usually 0.1% by mass or more, preferably 0.8%. 2 mass% or more, more preferably 0.3 mass% or more, while the upper limit is usually 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less.

1-2. Solvent As the non-aqueous solvent, it is possible to use cyclic carbonates, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, sulfone compounds, and the like.
<Cyclic carbonate>
Examples of the cyclic carbonate include those having an alkylene group having 2 to 6 carbon atoms such as ethylene carbonate, propylene carbonate, butylene carbonate and the like. 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.

Further, cyclic carbonates having a fluorine atom (hereinafter sometimes abbreviated as “fluorinated cyclic carbonate”) can also be suitably used. The cyclic carbonate having a fluorine atom (hereinafter sometimes abbreviated 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 derivatives of cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, such as ethylene carbonate derivatives. Examples of the ethylene carbonate derivative include fluorinated products of ethylene carbonate or ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms), and particularly those having 1 to 8 fluorine atoms. Is preferred.

  Specifically, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4- Fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethyl Le ethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among them, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4,5-difluoro-4,5-dimethylethylene carbonate has high ionic conductivity. It is more preferable in terms of imparting properties and suitably forming an interface protective film.
A cyclic carbonate may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. The blending amount of the cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. However, in 100% by volume of the non-aqueous solvent, it is usually 5% by volume or more, preferably 10% by volume or more. The upper limit is usually 95% by volume or less, preferably 90% by volume or less, more preferably 85% by 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.

The fluorinated cyclic carbonate is not only a solvent but also the following 1-4. It also exhibits an effective function as an auxiliary described in 1.
<Chain carbonate>
As a chain carbonate, a C3-C7 thing is preferable. Specifically, as the chain carbonate having 3 to 7 carbon atoms, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, Examples include n-butyl methyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, t-butyl ethyl carbonate.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, a chain carbonate having a fluorine atom (hereinafter sometimes abbreviated 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 a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

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

  Fluorinated diethyl carbonate derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2-trifluoro). Ethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2,2, Examples include 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 usually 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and usually 90% by volume or less, preferably 85% by volume in 100% by volume of the non-aqueous solvent. It is as follows. By being in the said range, the viscosity of a non-aqueous electrolyte solution is made into an appropriate range, the fall of ionic conductivity is suppressed, and it becomes easy to make the large current discharge characteristic of a non-aqueous electrolyte secondary battery into a favorable range by extension. Further, it is possible to avoid a decrease in electrical conductivity due to a decrease in 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>
Examples of the cyclic carboxylic acid ester include those having 3 to 12 total carbon atoms in the structural formula. 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.

  The compounding amount of the cyclic carboxylic acid ester is usually 5% by volume or more, preferably 10% by volume or more, and usually 50% by volume or less, preferably 40% by volume or less in 100% by volume of the non-aqueous solvent. By being in the said range, it becomes 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. In addition, 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 the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range. .

<Chain carboxylic acid ester>
Examples of the chain carboxylic acid ester include those having 3 to 7 carbon atoms in the structural formula. Specifically, methyl acetate, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-t-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, Isopropyl propionate, n-butyl propionate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, isobutyric acid-n- Examples include propyl and isopropyl isobutyrate.

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.
The amount of the chain carboxylic acid ester is usually 10% by volume or more, preferably 15% by volume or more, and usually 60% by volume or less, preferably 50% by volume or less in 100% by volume of the non-aqueous solvent. By being in the said range, it becomes 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. Further, the 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.
Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2 -Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoro) Ethyl) ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) Ether, ethyl (2,2,3,3-tetrafluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl Ether, (2-fluoroethyl) (3-fluoro-n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2, 2,3,3-tetrafluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl -N-propyl ether, (2,2,2-trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro Olo-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2 , 2,3,3,3-pentafluoro-n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3 -Fluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) ) (2,2,3,3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) Ether, di-n-propyl Ether, (n-propyl) (3-fluoro-n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3 , 3-tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, ( 3-Fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether , (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3 3,3-triflu (Ro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3,3-penta Fluoro-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, methoxy Ethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoro Ethoxy) 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-tetrafluoroe Xyl) 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-tetrafluoro) Ethoxy) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2 -Fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2- (Luoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) (1,1,2,2 -Tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-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.

  The compounding amount of the ether compound is usually 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and usually 70% by volume or less, preferably 60% by volume in 100% by volume of the non-aqueous solvent. Hereinafter, it is more preferably 50% by volume or less. By being within the above range, it is easy to ensure the improvement effect of the lithium ion dissociation of the chain ether and the improvement of the ionic conductivity derived from the decrease in viscosity. When the negative electrode active material is a carbonaceous material, the chain ether is lithium. It is easy to avoid a situation where the capacity is reduced due to co-insertion with ions.

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

Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.
The sulfolane is preferably sulfolane and / or a sulfolane derivative (hereinafter sometimes abbreviated as “sulfolane” including sulfolane). 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-methyl sulfolane, 3-methyl sulfolane, 2-fluoro sulfolane, 3-fluoro sulfolane, 2,2-difluoro sulfolane, 2,3-difluoro sulfolane, 2,4-difluoro sulfolane, 2,5-difluoro sulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methyl sulfolane, 5-fluoro-3-methyl sulfolane, 5-fluoro-2-methyl sulfolane, 2-fluoromethyl sulfolane, 3-fluoromethyl sulfolane, 2-trifluoromethyl sulfolane, 3- Trifluoromethylsulfolane, -Fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane, 5-fluoro-3- (trifluoromethyl) sulfolane Are preferable in view of high ion conductivity and high input / output.

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

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl 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, O is preferable high points.

  The compounding amount of the sulfone compound is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and usually 40% by volume or less in 100% by volume of the non-aqueous solvent. , Preferably 35% by volume or less, more preferably 30% by volume or less. By being in the above-mentioned range, it is easy to obtain durability improvement effects such as cycle characteristics and storage characteristics, and the viscosity of the non-aqueous electrolyte solution can be set to an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging the non-aqueous electrolyte secondary battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity maintenance rate is reduced.

  These cyclic carbonates, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, sulfone compounds and the like may be used alone or in combination of two or more. It is preferable to use a compound comprising two or more groups in combination. For example, it is preferable to use a high dielectric constant solvent such as cyclic carbonates or cyclic carboxylic acid esters in combination with a low viscosity solvent such as chain carbonates or chain carboxylic acid esters.

  One preferable combination of the non-aqueous solvent is a combination mainly composed of a cyclic carbonate and a chain carbonate. Among them, the total of the cyclic carbonate and the chain carbonate in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and the cyclic carbonate and the chain carbonate. The ratio of the cyclic carbonate with respect to the total is preferably 5% by volume or more, more preferably 10% by volume or more, still more preferably 15% by volume or more, preferably 50% by volume or less, more preferably 35% by volume or less, It is preferably 30% by volume or less, particularly preferably 25% by volume or less. Use of a combination of these non-aqueous solvents is preferable because of good balance between cycle characteristics and high-temperature storage characteristics (particularly, remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent.

Cyclic carbonates include ethylene carbonate, propylene carbonate, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4,5-difluoro-4,5-dimethylethylene carbonate. From the viewpoint of improving high-temperature storage characteristics.
Specific examples of preferred combinations of ethylene carbonate and chain carbonate include 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 Examples include methyl carbonate, ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Among them, those containing asymmetric linear alkyl carbonates as chain carbonates are more preferable, and in particular, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate and diethyl carbonate. And ethylene carbonate such as ethyl methyl carbonate, and those containing symmetric chain carbonates and asymmetric chain carbonates are preferred because of a good balance between cycle characteristics and large current discharge characteristics.

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, more preferably 95: 5 to 50:50. Further, the proportion of propylene carbonate in the whole non-aqueous solvent is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more, and usually 20% by volume or less, preferably 10% by volume or less, More preferably, it is 5 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.

  Specific examples of preferable combinations of monofluoroethylene carbonate and chain carbonate include monofluoroethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and diethyl carbonate, monofluoroethylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and dimethyl carbonate, Examples include diethyl carbonate, monofluoroethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

  A combination in which ethylene carbonate and / or propylene carbonate is further added to the combination of these monofluoroethylene carbonate and chain carbonate is also a preferable combination. The volume ratio of monofluoroethylene carbonate to ethylene carbonate and / or propylene carbonate when ethylene carbonate and / or propylene carbonate is added is preferably 1: 3 to 3: 1, more preferably 1: 2 to 2: 1. . When ethylene carbonate and / or propylene carbonate is contained in this concentration range, the electrical conductivity of the electrolytic solution can be ensured while forming a stable protective film on the negative electrode.

  Further, when diethyl carbonate is contained in the non-aqueous solvent, the proportion of diethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more, It is preferably 30% by volume or more, and is usually 90% by volume or less, preferably 80% by volume or less, more preferably 75% by volume or less, and still more preferably 70% by volume or less. If it is contained in the above range, gas generation during high-temperature storage may be suppressed.

  In the case where dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more. It is preferably 30% by volume or more, and is usually 90% by volume or less, preferably 80% by volume or less, more preferably 75% by volume or less, and further preferably 70% by volume or less. When it is contained in the above range, 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 battery characteristics after high-temperature storage are improved while ensuring the electrical conductivity of the electrolyte. This is preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents (dimethyl carbonate / ethyl methyl carbonate) is 0.8 or more in terms of improving the electrical conductivity of the electrolyte and improving the battery characteristics after storage. Is preferable, and 1 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 addition, in the combination mainly composed of the cyclic carbonates and the chain carbonates, the cyclic carbonates other than the cyclic carbonates and the chain carbonates, the chain carbonates, the cyclic carboxylic acid esters, and the chain carboxylic acid esters. , Cyclic ethers, chain ethers, sulfone compounds, and other solvents may be mixed.
Another example of the preferred non-aqueous solvent is an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, or a mixed solvent consisting of two or more organic solvents selected from the group. It occupies 60% by volume or more. A non-aqueous electrolyte using this mixed solvent may reduce solvent evaporation and liquid leakage even when used at high temperatures. Among them, the total of ethylene carbonate and propylene carbonate in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and the volume of ethylene carbonate and propylene carbonate. When the ratio is preferably 30:70 to 60:40, the balance between cycle characteristics and high-temperature storage characteristics may be improved.

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.
1-3. The compound represented by the general formula (1) and the compound represented by the general formula (2) The present invention contains a compound represented by the following general formula (1) in the non-aqueous electrolyte solution, and further includes the following general formula It is characterized by containing a compound represented by the formula (2).

(In the formula (1), X and Z represent CR ¹ ₂ , C═O, C═N—R ¹ , C═P—R ¹ , O, S, N—R ¹ , P—R ^{1 and} are the same. However, Y represents CR ¹ ₂ , C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ where , R and R ¹ are hydrogen, halogen, or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, and R ² represents a functional group. .R ³ from carbon atoms 1 also a hydrocarbon group of 20 has the, Li, ^NR _{4 4,} or a hydrocarbon group having carbon atoms 1 may have a functional group 20 .R ⁴ Is a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, n and m each represents an integer of 0 or more, and W represents the above R. .

In formula (2), R ^{5 to} R ¹⁰ each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 12 carbon atoms, an ether group or an ester group which may have a halogen atom. )
<Compound represented by the general formula (1)>
Wherein, X and Z have the general formula (1) is not particularly limited as long as the scope of the described, _{^{preferably, CR 1 2, O, S}} , N-R are more preferred. Y is not particularly limited as long as it is within the range described in the general formula (1), but preferably C═O, S═O, S (═O) ₂ , P (═O) —R ² , P ( ═O) —OR ³ is more preferred. R and R ¹ are not particularly limited as long as they are within the range described in the general formula (1), but preferably have hydrogen, fluorine, a saturated aliphatic hydrocarbon group which may have a substituent, or a substituent. Examples thereof may include an unsaturated aliphatic hydrocarbon group which may be substituted, and an aromatic hydrocarbon group which may have a substituent.

R ² and R ⁴ are not particularly limited as long as they are within the range described in the general formula (1), but are preferably a saturated aliphatic hydrocarbon group that may have a substituent or a substituent. Examples thereof include unsaturated aliphatic hydrocarbons and optionally substituted aromatic hydrocarbons / aromatic heterocycles.
R ³ is not particularly limited as long as it is within the range described in the general formula (1), but preferably Li, a saturated aliphatic hydrocarbon which may have a substituent, or an unsaturated which may have a substituent Examples thereof include an aliphatic hydrocarbon and an aromatic hydrocarbon / aromatic heterocycle which may have a substituent.

  As a saturated aliphatic hydrocarbon which may have a substituent, an unsaturated aliphatic hydrocarbon which may have a substituent, a substituent of an aromatic hydrocarbon / aromatic heterocycle which may have a substituent Is not particularly limited, but preferably a saturated aliphatic hydrocarbon group which may have a substituent such as halogen, carboxylic acid, carbonic acid, sulfonic acid, phosphoric acid, phosphorous acid, or a substituent. Examples thereof include a preferable unsaturated aliphatic hydrocarbon group and an ester of an aromatic hydrocarbon group which may have a substituent, and more preferable is halogen, and most preferable is fluorine.

  Preferable saturated aliphatic hydrocarbons include, specifically, methyl group, ethyl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, 1-fluoroethyl group, 2-fluoroethyl group, 1,1-difluoroethyl. Group, 1,2-difluoroethyl group, 2,2-difluoroethyl group, 1,1,2-trifluoroethyl group, 1,2,2-trifluoroethyl group, 2,2,2-trifluoroethyl group , A cyclopentyl group, and a cyclohexyl group are preferable.

Specific preferred unsaturated aliphatic hydrocarbons include ethenyl, 1-fluoroethenyl, 2-fluoroethenyl, 1-methylethenyl, 2-propenyl, and 2-fluoro-2-propenyl. 3-fluoro-2-propenyl group, ethynyl group, 2-fluoroethynyl group, 2-propynyl group and 3-fluoro-2propynyl group are preferable.
Preferred aromatic hydrocarbons include phenyl group, 2-fluorophenyl group, 3-fluorophenyl group, 2,4-difluorophenyl group, 2,6-difluorophenyl group, 3,5-difluorophenyl group, 2, 4 , 6-trifluorophenyl group is preferred.

Preferred aromatic heterocycles are 2-furanyl group, 3-furanyl group, 2-thiophenyl group, 3-thiophenyl group, 1-methyl-2-pyrrolyl group, and 1-methyl-3-pyrrolyl group.
Among these, a methyl group, an ethyl group, a fluoromethyl group, a trifluoromethyl group, a 2-fluoroethyl group, a 2,2,2-trifluoroethyl group, an ethenyl group, an ethynyl group, and a phenyl group are preferable.

More preferably, a methyl group, an ethyl group, and an ethynyl group are preferable.
n and m are not particularly limited as long as they are within the range described in the general formula (1), but are preferably 0 or 1, and more preferably n = m = 1 or n = 1 and m = 0.
The molecular weight is preferably 50 or more. Moreover, Preferably, it is 500 or less. If it is this range, the solubility with respect to a non-aqueous electrolyte solution will be easy to be ensured, and the effect of this invention will fully be expressed easily. Specific examples of these preferred compounds include

Etc.
Among these, it is preferable that R is hydrogen, a fluorine, or an ethynyl group from both the reactivity and the stability. By being a fluorine or ethynyl group, it is possible to prevent a decrease in expected characteristics due to a decrease in reactivity. In addition, the halogen other than fluorine prevents the case where the reactivity is too high and the side reaction increases.

The number of fluorine or ethynyl groups in R is preferably within 2 in total. By being in the said range, the deterioration of compatibility with electrolyte solution and the case where reactivity is too high and a side reaction increases are prevented.
Among these, n = 1 and m = 0 are preferable. When both are 0, stability deteriorates from the distortion of the ring, the reactivity becomes too high, and there is a possibility that side reactions increase. Further, even if n = 2 or more, or n = 1, when m = 1 or more, there is a possibility that the chain is more stable than the ring and the initial characteristics may not be exhibited.

Furthermore, wherein, X and Z are, ^CR _{1 2} or O are more preferred. By being CR ¹ ₂ or O, the case where the reactivity is too high to increase the side reaction is prevented.
The molecular weight is more preferably 100 or more, and more preferably 200 or less. If it is this range, it will be easy to ensure further the solubility of General formula (1) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be further fully expressed easily.

  Specific examples of these more preferable compounds include

Can be given.
More preferably, R is all hydrogen. In this case, the side reaction is most likely to be suppressed while maintaining the expected characteristics. Further, when Y is C = O or S = O, one of X and Z is O, indicating that Y is S (= O) ₂ , P (= O) -R ² , P (= O In the case of —OR ³ , it is preferred that both X and Z are O or CH ₂ , or one of X and Z is O and the other is CH ₂ . When Y is C═O or S═O, if both X and Z are CH ₂ , the reactivity may be too high and side reactions may increase.

  Specifically, as these compounds,

Can be given.
On the other hand, the compound represented by the general formula (3) is preferable from the viewpoint of ease of industrial production.

(Y represents C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ , where R ² may have a functional group. A hydrocarbon group having 1 to 20. R ³ is Li, NR ⁴ ₄ or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and R ⁴ has a functional group. And may be the same or different from each other.
As these compounds having preferable conditions, specifically,

Can be given.
The compound represented by General formula (1) may be used individually by 1 type, or may have 2 or more types by arbitrary combinations and ratios. Moreover, the compounding quantity of the compound represented by General formula (1) is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The compounding amount of the compound represented by the general formula (1) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more in 100% by mass of the non-aqueous electrolyte solution. Moreover, it is 5 mass% or less normally, Preferably it is 4 mass% or less, More preferably, it is 3 mass% or less. By being in the above range, it is easy for the non-aqueous electrolyte secondary battery to exhibit a sufficient cycle characteristic improving effect, and it is easy to avoid a situation in which the high-temperature storage characteristic is lowered and the discharge capacity retention rate is lowered. Further, the effect of the present invention is sufficient, and the case where the resistance is further increased and the output and load characteristics are deteriorated is prevented.

<Compound represented by formula (2)>
In formula (2), R ^{5 to} R ¹⁰ may each independently have a hydrogen atom, a halogen atom, a C 1-12 hydrocarbon group that may have a halogen atom, or a halogen atom. It represents either an ether group or an ester group optionally having a halogen atom.
Among them, R ^{5 to} R ¹⁰ are preferably each independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 12 carbon atoms which may have a halogen atom.

Examples of the halogen atom include fluorine, chlorine, bromine and the like, and those which are fluorine are preferable.
As a C1-C12 hydrocarbon group which may have a halogen atom, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C6-C12 aryl group, or carbon Examples thereof include aralkyl groups of 7 to 12.

  Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, and n-pentyl. Group, t-pentyl group, n-hexyl group, 1,1-dimethylbutyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group and the like. An alkyl group having 1 to 6 carbon atoms, particularly 3 to 6 carbon atoms is preferable.

As a C2-C12 alkenyl group, a vinyl group, a propenyl group, etc. are mentioned, Preferably it is C2-C8, Most preferably, a C2-C4 thing is mentioned.
Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, and an ethylphenyl group, and among them, a phenyl group is preferable.
Examples of the aralkyl group having 7 to 12 carbon atoms include a benzyl group and a phenethyl group, and among them, a benzyl group is preferable.

The alkyl group, alkenyl group, aryl group and aralkyl group may be substituted with a halogen atom. Examples of the group substituted with fluorine include a trifluoromethyl group, a trifluoroethyl group and a pentafluoroethyl group. Fluorinated alkyl groups, 2-fluorovinyl groups, fluorinated alkenyl groups such as 3-fluoro-2-propenyl group, fluorinated aryl groups such as 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group Fluorinated aralkyl groups such as 2-fluorobenzyl group, 3-fluorobenzyl group and 4-fluorobenzyl group.

Among these hydrocarbon groups having 1 to 12 carbon atoms which may have a halogen atom, those having an alkyl group or an aryl group are preferable, and at least one of R ^{5 to} R ¹⁰ is an alkyl having 3 or more carbon atoms. The group is more preferable, and an alkyl group having 4 or more carbon atoms is particularly preferable.
The alkyl group having 4 or more carbon atoms is preferably a secondary alkyl group or a tertiary alkyl group, and among them, a sec-butyl group, a t-butyl group, a t-pentyl group, a 1,1-dimethylbutyl group, a cyclopentyl group. Group and cyclohexyl group are more preferable, and t-butyl group, t-pentyl group, 1,1-dimethylbutyl group, cyclopentyl group and cyclohexyl group are more preferable.

Examples of the C1-C12 ether group that may have a halogen atom include a methoxy group, an ethoxy group, a propoxy group, a phenoxy group, and the like, and among them, a methoxy group and a phenoxy group are preferable.
Examples of the ester group having 1 to 12 carbon atoms that may have a halogen atom include a carbonic acid ester group, a carboxylic acid ester group, and a sulfonic acid ester group.

Examples of the carbonic acid ester group include a methyl carbonic acid ester group, an ethyl carbonic acid ester group, a propyl carbonic acid ester group, and a phenyl carbonic acid ester group. Among them, a methyl carbonic acid ester group and a phenyl carbonic acid ester group are preferable.
Examples of the carboxylic acid ester group include an acetic acid ester group, a propionic acid ester group, and a butyric acid ester group, and among them, an acetic acid ester group and a propionic acid ester group are preferable.

Examples of the sulfonic acid ester group include a methanesulfonic acid ester group, an ethanesulfonic acid ester group, and a propanesulfonic acid ester group. Among them, a methanesulfonic acid ester group and an ethanesulfonic acid ester group are preferable.
Specific examples of the compound represented by the general formula (2) include the following compounds.

Benzene, methylbenzene, ethylbenzene, n-propylbenzene, i-propylbenzene, n-butylbenzene, i-butylbenzene, sec-butylbenzene, t-butylbenzene, n-pentylbenzene, t-pentylbenzene, n-hexyl Benzene, cyclopentylbenzene, cyclohexylbenzene, 2-fluoro-methylbenzene, 3-fluoro-methylbenzene, 4-fluoro-methylbenzene, 2-fluoro-ethylbenzene, 3-fluoro-ethylbenzene, 4-fluoro-ethylbenzene, 2-fluoro -N-butylbenzene, 3-fluoro-n-butylbenzene, 4-fluoro-n-butylbenzene, 2-fluoro-t-butylbenzene, 3-fluoro-t-butylbenzene, 4-fluoro-t-butylbenzene 2-fluoro -t- pentyl, 3- fluoro -t- pentylbenzene, 4-fluoro -t- pentylbenzene, 2-fluoro - cyclohexylbenzene, 3-fluoro - cyclohexylbenzene, 4-fluoro - R and cyclohexyl benzene ⁵ to R ¹⁰ are each independently a hydrogen atom, a halogen atom, the compound is an alkyl group having 1 to 12 carbon atoms which may have a halogen atom.

Biphenyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, 2-ethylbiphenyl, 3-ethylbiphenyl, 4-ethylbiphenyl, 2-fluorobiphenyl, 3-fluorobiphenyl, 4-fluorobiphenyl, 2,2 R ^{5 to} R ¹⁰ such as' -difluorobiphenyl, 3,3'-difluorobiphenyl, 4,4'-difluorobiphenyl, 2,4-difluorobiphenyl each independently have a hydrogen atom, a halogen atom, or a halogen atom. The compound which is a C1-C12 aryl group which may have.

  Methoxybenzene, ethoxybenzene, propoxybenzene, phenoxybenzene, 2-fluoro-methoxybenzene, 3-fluoro-methoxybenzene, 4-fluoro-methoxybenzene, 2,3-difluoro-methoxybenzene, 2,4-difluoro-methoxybenzene 2,5-difluoro-methoxybenzene, 2,6-difluoro-methoxybenzene, 3,4-difluoro-methoxybenzene, 3,5-difluoro-methoxybenzene and other compounds having an ether group.

  Methylphenyl carbonate, ethylphenyl carbonate, n-propylphenyl carbonate, diphenyl carbonate, (2-fluorophenyl) methyl carbonate, (3-fluorophenyl) methyl carbonate, (4-fluorophenyl) methyl carbonate, (2-fluorophenyl) Phenyl carbonate, (3-fluorophenyl) phenyl carbonate, (4-fluorophenyl) phenyl carbonate, (2-t-butylphenyl) methyl carbonate, (3-t-butylphenyl) methyl carbonate, (4-t-butylphenyl) ) Methyl carbonate, (2-t-butylphenyl) phenyl carbonate, (3-t-butylphenyl) phenyl carbonate, (4-t-butylphenyl) phenyl carbonate, 2-t-pentylphenyl) methyl carbonate, (3-t-pentylphenyl) methyl carbonate, (4-t-pentylphenyl) methyl carbonate, (2-t-pentylphenyl) phenyl carbonate, (3-t-pentylphenyl) ) Phenyl carbonate, (4-t-pentylphenyl) phenyl carbonate, (2-cyclohexylphenyl) methyl carbonate, (3-cyclohexylphenyl) methyl carbonate, (4-cyclohexylphenyl) methyl carbonate, (2-cyclohexylphenyl) phenyl carbonate , (3-cyclohexylphenyl) phenyl carbonate, (4-cyclohexylphenyl) phenyl carbonate and other compounds having a carbonate group.

  Phenylacetate, phenylpropionate, phenylbutyrate, 2-fluorophenylacetate, 3-fluorophenylacetate, 4-fluorophenylacetate, 2-fluorophenylpropionate, 3-fluorophenylpropionate, 4-fluorophenylpropionate, 2-n-butylphenyl acetate, 3-n-butylphenyl acetate, 4-n-butylphenyl acetate, 2-t-butylphenyl acetate, 3-t-butylphenyl acetate, 4-t-butylphenyl acetate, 2- t-pentylphenyl acetate, 3-t-pentylphenyl acetate, 4-t-pentylphenyl acetate, 2-cyclohexylphenyl acetate, 3-cyclohexylphenyl acetate, 4-cyclo Xylphenylacetate, 2-n-butylphenylpropionate, 3-n-butylphenylpropionate, 4-n-butylphenylpropionate, 2-t-butylphenylpropionate, 3-t-butylphenylpropionate, 4 -T-butylphenylpropionate, 2-t-pentylphenylpropionate, 3-t-pentylphenylpropionate, 4-t-pentylphenylpropionate, 2-cyclohexylphenylpropionate, 3-cyclohexylphenylpropionate, 4 -A compound having a carboxylic acid ester group such as cyclohexylphenylpropionate.

Phenyl methanesulfonate, phenyl ethanesulfonate, phenyl propanesulfonate, methanesulfonic acid (2-fluorophenyl), methanesulfonic acid (3-fluorophenyl), methanesulfonic acid (4-fluorophenyl), ethanesulfonic acid (2 -Fluorophenyl), ethanesulfonic acid (3-fluorophenyl), ethanesulfonic acid (4-fluorophenyl), methanesulfonic acid (2-n-butylphenyl), methanesulfonic acid (3-n-butylphenyl), methane Sulfonic acid (4-n-butylphenyl), methanesulfonic acid (2-t-butylphenyl), methanesulfonic acid (3-t-butylphenyl), methanesulfonic acid (4-t-butylphenyl), methanesulfonic acid (2-t-pentylphenyl), methanesulfonic acid (3-t Pentylphenyl), methanesulfonic acid (4-t-pentylphenyl), methanesulfonic acid (2-cyclohexylphenyl), methanesulfonic acid (3-cyclohexylphenyl), methanesulfonic acid (4-cyclohexylphenyl), ethanesulfonic acid ( 2-n-butylphenyl), ethanesulfonic acid (3-n-butylphenyl), ethanesulfonic acid (4-n-butylphenyl), ethanesulfonic acid (2-t-butylphenyl), ethanesulfonic acid (3- t-butylphenyl), ethanesulfonic acid (4-t-butylphenyl), ethanesulfonic acid (2-t-pentylphenyl), ethanesulfonic acid (3-t-pentylphenyl), ethanesulfonic acid (4-t- Pentylphenyl), ethanesulfonic acid (2-cyclohexylphenyl), eta Acid (3-phenyl), compounds having a sulfonic acid ester group such as ethanesulfonic acid (4-cyclohexyl-phenyl).

Among the above compounds, at least one of R ^{5 to} R ¹⁰ in the general formula (2) is an alkyl group having 3 or more carbon atoms or an aryl group from the viewpoint of improving battery protection characteristics during overcharge and improving high-temperature storage characteristics. Group, a carbonic acid ester group is preferable, an alkyl group having 4 or more carbon atoms is more preferable, and a t-butyl group, a t-pentyl group, a cyclopentyl group, or a cyclohexyl group is particularly preferable.

  The compound represented by the general formula (2) may be used alone or in combination of two or more. The proportion of the compound represented by the general formula (2) in the non-aqueous electrolyte is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably. It is 0.1 mass% or more, and is usually 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less. By being in the said range, the effect of this invention becomes easy to express and the fall of the capacity | capacitance of a battery is prevented.

1-4. Auxiliary agent In the non-aqueous electrolyte battery of the present invention, an auxiliary agent may be appropriately used according to the purpose in addition to the compounds of the general formulas (1) and (2). Examples of the auxiliary agent include cyclic carbonates having unsaturated bonds shown below, cyclic carbonates having fluorine atoms, unsaturated cyclic carbonates having fluorine atoms, and other auxiliary agents.

<Cyclic carbonate having an unsaturated bond>
In the non-aqueous electrolyte of the present invention, in order to form a film on the negative electrode surface of the non-aqueous electrolyte battery and to extend the life of the battery, in addition to the compound of formula (1), the compound of formula (1) A cyclic carbonate having an unsaturated bond excluding the above (hereinafter sometimes abbreviated as “unsaturated cyclic carbonate”) can be used.

The unsaturated cyclic carbonate is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond, and any unsaturated cyclic carbonate can be used. Note that the cyclic carbonate having a substituent having an aromatic ring is also included in the unsaturated cyclic carbonate.
Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond, 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-vinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate.

  Specific examples of ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4- Allyl-5-vinylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene Examples thereof include carbonate and 4-methyl-5-allylethylene carbonate.

Among these, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, vinyl ethylene carbonate, and 4,5-divinyl ethylene carbonate are more preferably used because they form a stable interface protective film.
An unsaturated cyclic carbonate may be used individually by 1 type, or may have 2 or more types by arbitrary combinations and ratios. 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 usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more in 100% by mass of the non-aqueous electrolyte solution. 5% by mass or less, preferably 4% by mass or less, more 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. Further, the effects of the present invention can be sufficiently exerted, and the case where the resistance is further increased and the output and load characteristics are deteriorated is prevented.

<Cyclic carbonate having a fluorine atom>
Examples of the cyclic carbonate having a fluorine atom include derivatives of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, such as an ethylene carbonate derivative. Examples of the ethylene carbonate derivative include fluorinated products of ethylene carbonate or ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms), and particularly those having 1 to 8 fluorine atoms. Is preferred.

  Specifically, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4- Fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethyl Le ethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among these, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4,5-difluoro-4,5-dimethylethylene carbonate is preferably interface protection. It is more preferable at the point which forms a film.
The cyclic carbonate having a fluorine atom may be used alone or in combination of two or more in any combination and ratio. Moreover, the compounding quantity of the cyclic carbonate which has a fluorine atom is not restrict | limited in particular, Unless the effect of this invention is impaired remarkably, it is arbitrary. The compounding amount of the cyclic carbonate having a fluorine atom is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, in 100% by mass of the non-aqueous electrolyte. The amount is usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less. By being in the said range, it is easy to avoid the situation where a non-aqueous electrolyte secondary battery tends to express sufficient cycling characteristics improvement effect, and gas generation amount increases. In addition, the effects of the present invention can be sufficiently exerted, and the case where resistance is further increased and output and load characteristics are deteriorated is prevented.

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

Examples of the fluorinated unsaturated cyclic carbonate include a fluorinated vinylene carbonate derivative, a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond.
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.

  Examples of the fluorinated ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon double bond include 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-diflu B-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4- Examples thereof include phenylethylene carbonate.

  Among them, 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-diallylethylenecar Sulfonates, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl carbonate is more preferably used because it forms a stable interface protective coating.

  A fluorinated unsaturated cyclic carbonate may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. Moreover, the compounding quantity of a fluorinated 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 fluorinated unsaturated cyclic carbonate is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more in 100% by mass of the non-aqueous electrolyte. Moreover, it is 5 mass% or less normally, Preferably it is 4 mass% or less, More preferably, it is 3 mass% or less. By being in the above 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. It is easy to avoid such a situation. Further, the effects of the present invention can be sufficiently exerted, and the case where the resistance is further increased and the output and load characteristics are deteriorated is prevented.

<Other auxiliaries>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. Examples of other auxiliary agents include erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate, methoxyethyl-ethyl carbonate, ethoxyethyl-methyl carbonate, ethoxyethyl-ethyl carbonate, etc. Carbonate compounds: succinic anhydride, glutaric anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, glutaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic acid Carboxylic anhydrides such as acid anhydrides; dimethyl succinate, diethyl succinate, diallyl succinate, dimethyl maleate, diethyl maleate, diallyl maleate, dipropyl maleate, dibutyl maleate, Dicarboxylic acid diester compounds such as bis (trifluoromethyl) inate, bis (pentafluoroethyl) maleate, bis (2,2,2-trifluoroethyl) maleate; 2,4,8,10-tetraoxaspiro [5.5] Spiro compounds such as undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, propylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethylmethanesulfonate, methyl-methoxymethanesulfonate, methyl-2-methoxyethanesulfonate , Busulfan, diethylene glycol dimeta Sulfonate, 1,2-ethanediol bis (2,2,2-trifluoroethane sulfonate), 1,4-butanediol bis (2,2,2-trifluoroethane sulfonate), sulfolane, 3-sulfolene, 2- Sulfolene, dimethylsulfone, diethylsulfone, divinylsulfone, diphenylsulfone, bis (methylsulfonyl) methane, bis (methylsulfonyl) ethane, bis (ethylsulfonyl) methane, bis (ethylsulfonyl) ethane, bis (vinylsulfonyl) methane, bis Sulfur-containing compounds such as (vinylsulfonyl) ethane, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, N, N-dimethyltrifluoromethanesulfonamide, N, N-diethyltrifluoromethanesulfonamide; 1 Nitrogen-containing compounds such as methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, succinimide and N-methylsuccinimide; heptane , Hydrocarbon compounds such as octane, nonane, decane, cycloheptane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, n-butylcyclohexane, t-butylcyclohexane, dicyclohexyl; acetonitrile, propionitrile, butyronitrile, valeronitrile, lauronitrile, Acrylonitrile, methacrylonitrile, crotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azeronitrile, sebacononitrile, urine Nitrile compounds such as decandinitrile and dodecandinitrile; methyl dimethyl phosphinate, ethyl dimethyl phosphinate, ethyl diethyl phosphinate, trimethylphosphonoformate, triethylphosphonoformate, trimethylphosphonoacetate, triethylphosphonoacetate, trimethyl Examples thereof include phosphorus-containing compounds such as -3-phosphonopropionate and triethyl-3-phosphonopropionate. Among these, ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, busulfan, 1,4 in terms of improving battery characteristics after high-temperature storage -Sulfur-containing compounds such as butanediol bis (2,2,2-trifluoroethanesulfonate); nitrile compounds such as acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are preferable.

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 usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and usually 5% by mass in 100% by mass of the non-aqueous electrolyte. Hereinafter, it is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. By being in the said range, the effect of other adjuvants can be made to fully express and it is easy to avoid the situation where battery characteristics, such as a high load discharge characteristic, fall.

  The non-aqueous electrolyte solution described above includes those existing inside the non-aqueous electrolyte battery according to the present invention. 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 nonaqueous electrolyte solution in a nonaqueous electrolyte battery obtained by pouring into a separately assembled battery, the components of the nonaqueous electrolyte solution of the present invention are individually placed in the battery, In order to obtain the same composition as the non-aqueous electrolyte solution of the present invention by mixing in a non-aqueous electrolyte battery, the compound constituting the non-aqueous electrolyte solution of the present invention is further generated in the non-aqueous electrolyte battery. The case where the same composition as the aqueous electrolyte is obtained is also included.

2. Battery Configuration The non-aqueous electrolyte battery of the present invention is suitable for use as an electrolyte for a secondary battery, for example, a lithium secondary battery, among non-aqueous electrolyte batteries. Hereinafter, a non-aqueous electrolyte battery using the non-aqueous electrolyte of the present invention will be described.
The non-aqueous electrolyte secondary battery of the present invention can adopt a known structure. Typically, the negative electrode and the positive electrode capable of occluding and releasing ions (for example, lithium ions), and the non-aqueous electrolyte of the present invention described above. An aqueous electrolyte solution.

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

<Negative electrode active material>
Examples of the negative electrode active material include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like. Examples of the carbonaceous material used as the negative electrode active material include (1) natural graphite, (2) a carbonaceous material obtained by heat-treating the artificial carbonaceous material and the 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 at least two kinds of carbonaceous materials having different crystallinity and / or has an interface in contact with the different crystalline carbonaceous materials, (4) a negative electrode active material layer An initial irreversible capacity and a high current density are selected from carbonaceous materials comprising at least two kinds of carbonaceous materials having different orientations and / or having an interface in contact with the carbonaceous materials having different orientations. Good balance of charge / discharge characteristics is preferable. 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”). 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.

_{Li x Ti y M z O 4} (A)
[In the 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.
<Physical properties of carbonaceous materials>
When using a carbonaceous material as a 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.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to loss of initial battery capacity. On the other hand, when the above range is exceeded, when an electrode is produced by coating, an uneven coating surface tends to be formed, which may be undesirable in the battery production process.
The volume-based average particle size is measured by dispersing the carbon powder in a 0.2% by mass aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This is carried out 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.

When the Raman R value is below the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge / discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics.
On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.

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.
If the Raman half width is less than the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge and discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics. On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.

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 _{I A} of the peak _{P A} in the vicinity of 1580 cm ^-1, and measuring the intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1, the intensity ratio _{R (R = I B / I} A) Is calculated. 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 P _A in the vicinity of 1580 cm ^-1 of the resulting Raman spectrum was measured, which is defined as the Raman half-value 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: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half width analysis: background processing,
-Smoothing treatment: Simple average, 5 points of convolution (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 less than this range, the acceptability of lithium is likely to deteriorate during charging when used as a negative electrode material, lithium is likely to precipitate on the electrode surface, and stability may be reduced. On the other hand, if it exceeds this range, when used as a negative electrode material, the reactivity with the non-aqueous electrolyte increases, gas generation tends to increase, and a preferable battery may be difficult to obtain.

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.
(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. High current density charge / discharge characteristics improve as the degree of circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between particles is increased, and the high current density charge / discharge characteristics may be lowered for a short time.

  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 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, a mechanical / physical processing method of granulating a plurality of fine particles by the binder or the adhesive force of the particles themselves, etc. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and 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 below the above range, the packing density is difficult to increase when used as a negative electrode, and a high-capacity battery may not be obtained. On the other hand, when the above range is exceeded, there are too few voids between particles in the electrode, it is difficult to ensure conductivity between the particles, and it may be difficult to obtain preferable battery characteristics.

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.
(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 below the above range, the high-density charge / discharge characteristics may deteriorate. 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 X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) face: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) face: 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. If the aspect ratio exceeds the above range, streaking or a uniform coated surface cannot be obtained when forming an electrode plate, and the high current density charge / discharge characteristics may deteriorate. 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.

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

In the case of using an alloy-based material, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a technique such as vapor deposition, sputtering, or plating is also used.
(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the negative electrode current collector 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 is usually 100 μm or less, preferably 50 μm or less. This is because if the thickness of the negative electrode current collector is too thick, the capacity of the entire battery may be too low, and conversely if it is too thin, handling may be difficult.
(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 further 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 exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge. On the other hand, below the above range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease.

(Binder)
The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used in manufacturing the electrode.
Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, Rubber polymers such as NBR (acrylonitrile / butadiene rubber) and ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Soft resinous polymers such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10% by mass or less is further preferable, and 8% by mass or less is particularly preferable. When the ratio of the binder with respect to a negative electrode active material exceeds the said range, the binder ratio from which the amount of binders does not contribute to battery capacity may increase, and the fall of battery capacity may be caused. On the other hand, below the above range, the strength of the negative electrode may be reduced.

  In particular, when a rubbery polymer typified by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. When the main component contains a fluorine-based polymer typified by polyvinylidene fluoride, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. It is preferably 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.
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- Examples include dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.

In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and slurry it using a latex such as SBR. 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.
(Thickener)
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

Further, when using a thickener, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is more preferable.
When the ratio of the thickener to the negative electrode active material is less than the above range, applicability may be significantly reduced. Moreover, when it exceeds the said range, the ratio of the negative electrode active material which occupies for a negative electrode active material layer will fall, and the problem that the capacity | capacitance of a battery falls and the resistance between negative electrode active materials may increase.

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

(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 used for the positive electrode is described below.
(composition)
The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. For example, a material containing lithium and at least one transition metal is preferable. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable as the transition metal of the lithium transition metal composite oxide. Specific examples include lithium-cobalt composite oxides such as LiCoO ₂ and LiNiO ₂ . Lithium / nickel composite oxide, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _{4 and} other lithium / manganese composite oxides, part of transition metal atoms that are the main components of these lithium transition metal composite oxides are Na, K , B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, etc. And the like. As specific examples of the substituted ones, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _0.45 Co _0.1 Mn _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

  In addition, it is preferable to include lithium phosphate in the positive electrode active material because continuous charge characteristics are improved. Although there is no restriction | limiting in the use of lithium phosphate, It is preferable to mix and use the said positive electrode active material and lithium phosphate. The lower limit of the amount of lithium phosphate to be used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. The upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less.

(Surface coating)
Moreover, you may use what the substance of the composition different from this adhered to the surface of the said positive electrode active material. 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, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

  For example, these surface adhering substances are dissolved or suspended in a solvent, impregnated and added to the positive electrode active material, and dried. After the surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, It can be made to adhere to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing simultaneously. In addition, when making carbon adhere, the method of making carbonaceous adhere mechanically later in the form of activated carbon etc. can also be used, for example.

  The amount of the surface adhering substance is by mass with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and the upper limit, preferably 20% or less, more preferably, as the lower limit. Is used at 10% or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material and can improve the battery life. However, when the amount of the adhering quantity is too small, the effect is not sufficiently manifested. If it is too high, the resistance may increase in order to inhibit the entry and exit of lithium ions.

(shape)
Examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.
(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8
g / cm ³ or more, more preferably 1.0 g / cm ³ or more. If the tap density of the positive electrode active material is lower than the lower limit, the amount of the required dispersion medium increases when the positive electrode active material layer is formed, and the necessary amount of conductive material and binder increases, so that the positive electrode to the positive electrode active material layer The filling rate of the active material is restricted, and the battery capacity may be restricted. By using a complex oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. In general, the tap density is preferably as large as possible, and there is no particular upper limit, but if it is too large, diffusion of lithium ions using the electrolytic solution in the positive electrode active material layer as a medium is rate-limiting, and load characteristics may be easily reduced. The upper limit is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and still more preferably 3.5 g / cm ³ or less.

In the present invention, the tap density is 5 to 10 g of the positive electrode active material powder in a 10 ml glass graduated cylinder, and the powder packing density (tap density) g / cm ³ when tapped 200 times with a stroke of about 20 mm. Asking.
(Median diameter d ₅₀ )
The median diameter d ₅₀ of the positive electrode active material particles (secondary particle diameter when the primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, The upper limit is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. If the lower limit is not reached, a high tap density product may not be obtained. If the upper limit is exceeded, it takes time for the diffusion of lithium in the particles, resulting in a decrease in battery performance or production of the positive electrode of the battery, that is, an active material. When a conductive material, a binder, or the like is slurried with a solvent and applied as a thin film, problems such as streaking may occur. Here, by mixing two or more kinds of the positive electrode active materials having different median diameters d ₅₀ , the filling property at the time of producing the positive electrode can be further improved.

In the present invention, the median diameter d ₅₀ is measured by a known laser diffraction / scattering particle size distribution measuring apparatus. When LA-920 manufactured by HORIBA is used as a particle size distribution meter, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.
(Average primary particle size)
When primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.8 μm. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. If the above upper limit is exceeded, it is difficult to form spherical secondary particles, which adversely affects the powder filling property, or the specific surface area is greatly reduced, so that there is a high possibility that battery performance such as output characteristics will deteriorate. is there. On the other hand, when the value falls below the lower limit, there is a case where problems such as inferior reversibility of charge / discharge are usually caused because crystals are not developed.

In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.
(BET specific surface area)
The BET specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.00.
2 m ² / g or more, more preferably 0.3 m ² / g or more, and the upper limit is 50 m ² / g or less.
Preferably it is 40 m < ² > / g or less, More preferably, it is 30 m < ² > / g or less. If the BET specific surface area is smaller than this range, the battery performance tends to be lowered. If the BET specific surface area is larger, the tap density is difficult to increase, and a problem may occur in applicability when forming the positive electrode active material layer.

In the present invention, the BET specific surface area is determined by using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 150 ° C. for 30 minutes under nitrogen flow, and then atmospheric pressure. This is defined as a value measured by a nitrogen adsorption BET one-point method using a gas flow method, using a nitrogen-helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen to 0.3 is 0.3.
(Method for producing positive electrode active material)
As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, a transition metal raw material is dissolved or ground and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, and after drying as necessary, a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like is added and fired at a high temperature to obtain an active material. .

For the production of the positive electrode, the positive electrode active material may be used alone, or one or more of different compositions may be used in any combination or ratio. A preferable combination in this case is a combination of LiCoO ₂ and LiNi _0.33 Co _0.33 Mn _0.33 O 2 or LiMn ₂ O ₄ or a part of this Mn substituted with another transition metal or the like. Is mentioned.

<Configuration and manufacturing method of positive electrode>
The structure of the positive electrode will be described below. In the present invention, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. Manufacture of the positive electrode using a positive electrode active material can be performed by a conventional method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form into a sheet form are pressure-bonded to the positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

  The content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. Moreover, an upper limit becomes like this. Preferably it is 99 mass% or less, More preferably, it is 98 mass% or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

The positive electrode active material layer obtained by coating and drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material.
The density of the positive electrode active material layer is preferably 1.5 g / cm ³ or more as a lower limit, more preferably 2 g / cm ³ , further preferably 2.2 g / cm ³ or more, and preferably 5 g / cm ³ as an upper limit. ³ or less, more preferably 4.5 g / cm ³ or less, still more preferably 4 g / cm ³
The range is as follows.

If it exceeds this range, the permeability of the electrolyte solution to the vicinity of the current collector / active material interface decreases, and the charge / discharge characteristics particularly at a high current density decrease, and a high output may not be obtained. On the other hand, if it is lower, the conductivity between the active materials is lowered, the battery resistance is increased, and a high output may not be obtained.
(Conductive material)
A known conductive material can be arbitrarily used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

(Binder)
The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used during electrode production may be used. Resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber , Rubber polymers such as butadiene rubber and ethylene-propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / Ethylene copolymer, styrene Thermoplastic elastomeric polymer such as isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer Soft resinous polymers such as polymers; Fluoropolymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers; alkali metal ions (especially lithium ions) And a polymer composition having ion conductivity. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 50% by mass or less, preferably Is 20% by mass or less, more preferably 10% by mass or less, and most preferably 5% by mass or less. When the ratio 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. On the other hand, if it is too high, battery capacity and conductivity may be reduced.

(Slurry forming solvent)
As the solvent for forming the slurry, the positive electrode active material, the conductive material, the binder, and a solvent capable of dissolving or dispersing the thickener used as necessary may be used. There is no restriction, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone. Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) Amides such as dimethylformamide and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide.

In particular, when an aqueous medium is used, it is preferable to make a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios. When a thickener is further added, the ratio of the thickener to the active material is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more,
Moreover, as an upper limit, it is 5 mass% or less, Preferably it is 3 mass% or less, More preferably, it is the range of 2 mass% or less. Below this range, applicability may be significantly reduced. If it exceeds, the ratio of the active material in the positive electrode active material layer may decrease, and there may be a problem that the capacity of the battery decreases and a problem that the resistance between the positive electrode active materials increases.

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

  Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foam metal in the case of a metal material. A thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred. In addition, you may form a thin film suitably in mesh shape. Although the thickness of the thin film is arbitrary, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and the upper limit is usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the thin film is thinner than this range, the strength required for the current collector may be insufficient. Conversely, if the thin film is thicker than this range, the handleability may be impaired.

Moreover, it is also preferable from the viewpoint of reducing the electronic contact resistance between the current collector and the positive electrode active material layer that a conductive additive is applied to the surface of the current collector. Examples of the conductive assistant include noble metals such as carbon, gold, platinum, and silver.
The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is 20 The lower limit is preferably 15 or less, most preferably 10 or less, and the lower limit is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. Above this range, the current collector may generate heat due to Joule heat during high current density charge / discharge. Below this range, the volume ratio of the current collector to the positive electrode active material increases and the battery capacity may decrease.

(Electrode area)
When using the non-aqueous electrolyte of the present invention, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case from the viewpoint of increasing the stability at high output and high temperature. Specifically, the sum of the electrode areas of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, and more preferably 40 times or more. The outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. . In the case of a bottomed cylindrical shape, the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in the structure in which the positive electrode mixture layer is formed on both sides via the current collector foil. , The sum of the areas where each surface is calculated separately.

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

(Positive electrode surface coating)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said positive 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, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

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. Among these, polyolefin is preferable. 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-mentioned independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

2-4. 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 occupancy) is usually 40% or more, preferably 50% or more, and usually 95% or less, preferably 90% or less. .

  When the electrode group occupancy is below the above range, the battery capacity decreases. Also, if the above range is exceeded, the void space is small, the battery expands, and the member expands or the vapor pressure of the electrolyte liquid component increases and the internal pressure rises. In some cases, the gas release valve that lowers various characteristics such as storage at high temperature and the like, or releases the internal pressure to the outside is activated.

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

<Exterior case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, 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.

The shape of the outer case 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.
<Protective element>
Protective elements such as PTC (Positive Temperature Coefficient), thermal fuse, thermistor, whose resistance increases when abnormal heat generation or excessive current flows, cut off current flowing in the circuit due to sudden rise in battery internal pressure or internal temperature in 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.

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.
[Production of negative electrode]
The d-value of the lattice plane (002 plane) in X-ray diffraction is 0.336 nm, the crystallite size (Lc) is 652 nm, the ash content is 0.07 parts by mass, the median diameter by laser diffraction / scattering method is 12 μm, and the ratio by BET method The half-value width of a peak whose surface area is 7.5 m ² / g and R value (= I _B / I _A ) determined from Raman spectrum analysis using argon ion laser light is 0.12, 1570 to 1620 cm ^−1. 98 parts by weight of natural graphite powder having a weight of 19.9 cm ⁻¹ , 100 parts by weight of an aqueous dispersion of sodium carboxymethyl cellulose (concentration of 1% by weight of sodium carboxymethyl cellulose) and styrene-butadiene rubber as thickener and binder, respectively 1 part by weight of an aqueous dispersion (concentration of styrene-butadiene rubber 50% by weight), Mixed and was slurried in Isupaza. The obtained slurry was applied to a copper foil having a thickness of 12 μm, dried, and rolled with a press to obtain a negative electrode.

[Production of positive electrode]
90% by mass of LiCoO ₂ as a positive electrode active material, 5% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in an N-methylpyrrolidone solvent. And slurried. The obtained slurry was applied to both sides of an aluminum foil having a thickness of 15 μm, dried, and rolled with a press to obtain a positive electrode.

[Manufacture of electrolyte]
Under a dry argon atmosphere, a basic electrolyte solution was prepared by dissolving LiPF ₆ in a mixture of ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate (volume ratio 2: 3: 3) to a ratio of 1 mol / L. The basic electrolyte solution was mixed with the compounds described in Table 1 to obtain electrolyte solutions used in Examples 1 to 4 and Comparative Examples 1 to 5, respectively.

[Manufacture of lithium secondary batteries]
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. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and each of the electrolyte solutions shown in Table 1 was placed in the bag. The sheet-like battery was produced, and it was set as the battery used for Examples 1-4 and Comparative Examples 1-5, respectively.

[Evaluation of initial discharge capacity]
The sheet-like non-aqueous electrolyte secondary battery was charged to 4.2 V with a constant current corresponding to 0.2 C at 25 ° C. in a state of being sandwiched between glass plates in order to enhance the adhesion between the electrodes, and then 0 The battery was discharged to 3V with a constant current of 2C. This is done for 3 cycles to stabilize the battery. In the 4th cycle, after charging to 4.2V with a constant current of 0.5C, charging is performed until the current value reaches 0.05C with a constant voltage of 4.2V. The initial discharge capacity was determined by discharging to 3 V at a constant current of 0.2C.

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.
[Overcharge characteristics evaluation]
After the capacity evaluation test was completed, the battery was immersed in an ethanol bath and the volume was measured. Then, the battery was charged at a constant current of 0.2C to 5V at 45 ° C, and the current was cut when the voltage reached 5V. Then, the open circuit voltage (OCV) of the battery after the overcharge test was measured.

Next, the volume was measured by immersion in an ethanol bath, and the amount of gas generated from the volume change before and after overcharging was determined.
The lower the OCV of the battery after the overcharge test, the lower the overcharge depth, and the higher the overcharge protection characteristics. Further, the larger the amount of gas generated after overcharging, the more preferable the battery that senses this when the internal pressure rises abnormally due to an abnormality such as overcharging and operates the safety valve because the safety valve can be activated earlier. .

[High temperature storage characteristics evaluation test]
After the capacity evaluation test was completed, the volume was measured by immersing the battery in an ethanol bath, and after charging to 4.2 V at a constant current of 0.5 C, the current value became 0.05 C at a constant voltage of 4.2 V. The battery was charged until Thereafter, it was stored at a high temperature at 85 ° C. for 24 hours. After sufficiently cooling the battery, the volume was measured by immersion in an ethanol bath, and the amount of gas generated from the volume change before and after storage was determined. Next, the battery was discharged to 3 V at a constant current of 0.2 C at 25 ° C., the remaining capacity after the high-temperature storage characteristics test was measured, and the ratio of the remaining capacity to the initial discharge capacity was determined. %).

  As is apparent from Table 2, the battery of Comparative Example 1 is excellent in the amount of gas generated after high-temperature storage and the remaining capacity, but the amount of gas generated after overcharging is small and the protection characteristics during overcharging are low. The batteries of Comparative Examples 2 to 5 have a large amount of generated gas after overcharging and have high protection characteristics during overcharging, but the amount of generated gas and remaining capacity after high-temperature storage are poor. On the other hand, the batteries of Examples 1 to 4 have a large amount of gas generation after overcharging, high protection characteristics during overcharging, and excellent gas generation amount and remaining capacity after high-temperature storage. Therefore, it can be seen that the battery using the non-aqueous electrolyte according to the present invention has high protection characteristics during overcharge and excellent high-temperature storage characteristics.

  The non-aqueous electrolyte secondary battery using the non-aqueous electrolyte of the present invention has a high capacity retention rate even after an endurance test such as a high-temperature storage test or a cycle test, while enhancing the protection characteristics of the battery during overcharge. It 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 , 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 (5)

A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, wherein the non-aqueous electrolyte solution is represented by a compound represented by the following general formula (1) and the following general formula (2) And a non-aqueous electrolyte containing the compound.

(In the formula (1), X and Z represent CR ¹ ₂ , C═O, C═N—R ¹ , C═P—R ¹ , O, S, N—R ¹ , P—R ^{1 and} are the same. However, Y represents CR ¹ ₂ , C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ where , R and R ¹ are hydrogen, halogen, or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, and R ² represents a functional group. .R ³ from carbon atoms 1 also a hydrocarbon group of 20 has the, Li, ^NR _{4 4,} or a hydrocarbon group having carbon atoms 1 may have a functional group 20 .R ⁴ Is a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and may be the same or different from each other, n and m each represents an integer of 0 or more, and W represents the above R. .
In formula (2), R ^{5 to} R ¹⁰ may each independently have a hydrogen atom, a halogen atom, a C 1-12 hydrocarbon group that may have a halogen atom, or a halogen atom. It represents either an ether group or an ester group optionally having a halogen atom. ) The non-aqueous electrolyte solution according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the formula (3).

(Y represents C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ , where R ² may have a functional group. A hydrocarbon group having 1 to 20. R ³ is Li, NR ⁴ ₄ or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, and R ⁴ has a functional group. And may be the same or different from each other. In the compound represented by the above general formula (2), in formula (2), R ^{5 to} R ¹⁰ each independently have a hydrogen atom, a halogen atom, or a halogen atom and may have 1 to 12 carbon atoms. The nonaqueous electrolytic solution according to claim 1, wherein the nonaqueous electrolytic solution is a compound that is a hydrocarbon group.   The nonaqueous electrolytic solution according to any one of claims 1 to 3, wherein the nonaqueous electrolytic solution further contains a cyclic carbonate having a carbon-carbon double bond.   A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent that dissolves the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a positive electrode, the non-aqueous electrolyte solution being claimed Item 5. A nonaqueous electrolyte battery characterized by being a nonaqueous electrolyte solution according to any one of Items 1 to 4.