JP2016029650A - Nonaqueous electrolyte and nonaqueous electrolyte battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery whose initial irreversible capacity is improved, and a nonaqueous electrolyte.SOLUTION: The nonaqueous electrolyte contains a compound represented by formula (1) and further contains at least one of a fluorine-substituted oxoacid salt, an aromatic-containing carbonate ester, and a compound represented by formula (2). (Rto Rare each independently H or a 1-6C hydrocarbon group; n is an integer of 4-8; and A is a 1-12C organic group which may have a hetero element.) (R's are each a 1-12C organic group which may have a hetero element; m is an integer of 1-6; n1 is 0 and n2 is 1, or n1 is 1 and n2 is 0; and R's may be bonded together to form a ring.)SELECTED DRAWING: None

Description

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

With the rapid advancement of portable electronic devices such as mobile phones and notebook personal computers, there is an increasing demand for higher performance of secondary batteries used for the main power source and backup power source, such as nickel cadmium batteries and Non-aqueous electrolyte batteries such as lithium ion secondary batteries, which have a higher energy density than nickel-hydrogen batteries, are drawing attention.
Nonaqueous Electrolytic Solution The electrolytic solution used for the lithium secondary battery is usually composed mainly of an electrolyte and a nonaqueous solvent. The main components of the non-aqueous 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 addition, various non-aqueous solvents, electrolytes, auxiliaries, and the like have been proposed 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. . For example, Patent Document 1 discloses that cycle characteristics at room temperature are improved by adding an acrylate monomer to an electrolyte using a negative electrode mainly composed of graphite having a d ₀₀₂ plane spacing of less than 0.337 nm. Yes. Patent Document 2 discloses that discharge load characteristics and battery swelling are improved by using an acrylic monomer or an acrylic oligomer.

  Further, Patent Document 3 discloses that cycle characteristics and discharge load characteristics are improved by using a polyacrylate compound having three or more acrylic groups.

JP-A-6-163078 Japanese Patent Laid-Open No. 2002-158034 JP 2003-168479 A

As described above, in recent years, the demand for higher performance of secondary batteries is increasing, so that improvement of characteristics of lithium secondary batteries, that is, higher capacity, improvement of battery swelling, and the like are required. Under such circumstances, the non-aqueous electrolyte secondary battery using the electrolyte described in Patent Documents 1 to 3 has not yet been satisfactory in that the initial irreversible capacity increases. .
Accordingly, the present invention provides a non-aqueous electrolyte battery that solves the above-mentioned various problems that occur with respect to required performance in secondary batteries in recent years, and in particular, has improved the initial irreversible capacity of the battery. An object of the present invention is to provide a non-aqueous electrolyte suitable for the non-aqueous electrolyte battery.

  As a result of intensive studies to solve the above-mentioned problems, the inventors contain a compound represented by the following general formula (1) in the non-aqueous electrolyte used in the non-aqueous electrolyte battery, Non-aqueous system in which initial irreversible capacity is improved by containing at least one compound selected from the group consisting of a fluorine-substituted oxo acid salt, an aromatic-containing carbonate, and a compound represented by formula (2) The inventors have found that an electrolyte battery can be realized and have completed the present invention.

That is, the gist of the present invention is as follows.
(A) Nonaqueous electrolysis comprising a positive electrode capable of occluding and releasing metal ions, a negative electrode capable of occluding and releasing metal ions, and a nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent for dissolving the electrolyte. A non-aqueous electrolyte used in a liquid secondary battery, wherein the non-aqueous electrolyte contains a compound represented by the following general formula (1), and further includes a fluorine-substituted oxoacid salt, an aromatic-containing carbonate, and A non-aqueous electrolyte containing at least one compound selected from the group consisting of compounds represented by formula (2).

(R ^{1 to} R ³ each independently represent hydrogen that may be the same or different, or a hydrocarbon group having 1 to 6 carbon atoms. N represents an integer of 4 to 8. A represents carbon. (It represents an organic group that may have a heteroelement of 1 to 12)

(R ⁶ represents an organic group that may have a heteroelement having 1 to 12 carbon atoms, and may be the same or different. M represents an integer of 1 to 6, and n1 and n2 each represent Represents 0 or 1, and when n1 is 0, n2 is 1, and when n1 is 1, n2 is 0. R ⁶ may be bonded to form a ring.
(B) The non-aqueous electrolyte solution according to (a), wherein the fluorine-substituted oxoacid salt is at least one selected from the group consisting of difluorophosphate and fluorosulfate.
(C) The non-aqueous electrolyte further contains at least one compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom (a) Or the non-aqueous electrolyte solution in any one of (b).

(D) A non-aqueous electrolyte battery including a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is a non-aqueous electrolyte according to any one of (a) to (c) A non-aqueous electrolyte secondary battery, which is an aqueous electrolyte solution.

The present invention is characterized in that the compound represented by the general formula (1) is used in a non-aqueous electrolyte battery. Since the compound represented by the general formula (1) has a carbon-carbon double bond, it is first reduced at a potential that is not higher than the potential at which reductive decomposition of the solvent occurs to form a negative electrode SEI on the negative electrode. . At that time, if there is at least one compound selected from the group consisting of a fluorine-substituted oxoacid salt, an aromatic-containing carbonate, and a compound represented by the general formula (2), it is represented by them and the general formula (1). Reductive decomposition products of the compounds react to form a composite negative electrode SEI. At this time, the presence of four or more carbon-carbon double bonds in the molecule results in highly complex and a stronger negative electrode SEI. As a result, side reactions at the negative electrode are suppressed, and the initial irreversible capacity is suppressed.

  That is, by using the present invention, the initial irreversible capacity can be improved in a non-aqueous electrolyte battery, particularly a lithium secondary battery with a high voltage or high capacity.

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

1. TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, comprising a compound represented by the following general formula (1), and further containing a fluorine-substituted oxo The present invention relates to a nonaqueous electrolytic solution containing at least one compound selected from the group consisting of acid salts, aromatic carbonates, and general formula (2).

1-1. Electrolyte The electrolyte is not particularly limited as long as it is known to be used for non-aqueous electrolytes, and any lithium salt, sodium salt, or the like can be used. Here, specific examples of the lithium salt include the following.
For example, inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ ; LiN (FCO) ₂ , LiN (FCO) (FSO ₂ ) 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 (FSO 2) 3,} LiC (CF 3 SO 2) 3, LiC (C 2 F ₅ SO _{2) 3,} etc. Richiumumechido salts; lithium difluoro oxalatoborate, lithium bis (Okisara ) Lithium oxalatoborate salts borate; lithium tetrafluoro-oxa Lato phosphate, lithium difluoro (oxalato) phosphate, lithium-oxa Lato phosphate salts such as 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 , Fluorine-containing organic lithium salts such as LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; It is done.

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , etc., output characteristics, high rate charge / discharge characteristics, high temperature storage characteristics Has the effect of improving cycle characteristics, etc. Particularly preferred from the point.

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 and the} like, which has an effect of improving load characteristics and cycle characteristics. In this case, the concentration of LiBF ₄ with respect to 100% by mass of the entire non-aqueous electrolyte solution is not limited in the blending amount, and is arbitrary as long as the effect of the present invention is not significantly impaired.
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 its upper limit is usually 30% by mass or less, preferably 20% by mass or less.

  The concentration of these lithium salts in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range, and good battery performance is ensured. Therefore, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and further preferably 0.5 mol / L or more. Preferably it is 3 mol / L or less, More preferably, it is 2.5 mol / L or less, More preferably, it is 2.0 mol / L or less. If it is this range, since there is not too little lithium which is a charged particle and a viscosity can be made into an appropriate range, it will become easy to ensure favorable electrical conductivity.

1-2. Non-aqueous 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 4 carbon atoms.
Specific examples of the cyclic carbonate having 2 to 4 carbon atoms include alkylene carbonates having an alkylene group having 2 to 4 carbon atoms such as ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
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. The lower limit of the blending amount when one kind is used alone is usually 5% in 100% by volume of the non-aqueous solvent. Volume% or more, preferably 10 volume% or more. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the high current discharge characteristics, stability against the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery are in a good range. And it will be easier. Moreover, an upper limit is 60 volume% or less normally, More preferably, it is 50 volume% or less, More preferably, it is 40 volume% or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the load characteristics of the non-aqueous electrolyte battery are easily set in a favorable range.

  Moreover, one of the preferable combinations when using 2 or more types of cyclic carbonates by arbitrary combinations is the combination of ethylene carbonate and propylene carbonate. In this case, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, and particularly preferably 95: 5 to 50:50. Furthermore, the amount of propylene carbonate in the whole non-aqueous solvent is 0.1% by volume or more, preferably 1% by volume or more, more preferably 2% by volume or more, and the upper limit is usually 20% by volume or less, preferably 8% by volume. % Or less, more preferably 5% by volume or less. When propylene carbonate is contained within this range, the low temperature characteristics are further excellent, which is preferable.

Further, a cyclic carbonate having a fluorine atom (hereinafter sometimes abbreviated as “fluorinated cyclic carbonate”) can also be used, and the battery characteristics are further improved by containing a cyclic carbonate compound having a fluorine atom.
The cyclic carbonate compound having a fluorine atom can form a stable protective film on the surface of the negative electrode, suppress side reactions between the negative electrode and the electrolyte component, and improve high-temperature storage characteristics and cycle characteristics.
In general, when a cyclic carbonate compound having a fluorine atom is contained, the amount of gas generated tends to increase during high-temperature storage. By using the compound represented by the general formula (1) in combination, high-temperature storage is possible. It is preferable because capacity deterioration and gas generation amount at the time can be suppressed.

<Cyclic carbonate having a fluorine atom>
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, and 4,5-difluoroethylene carbonate gives high ionic conductivity and suitably forms an interface protective film. And more preferable.

  A fluorinated cyclic carbonate may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios. The blending amount of the fluorinated 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, preferably 5% by volume or more, more preferably 10% by volume or more. Further, it is preferably 15% by volume or more, preferably 40% by volume or less, more preferably 30% by volume or less, and still more preferably 25% by volume or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, avoiding a decrease in discharge capacity maintenance rate due to a decrease in high-temperature storage characteristics and an increase in gas generation amount. It's easy to do.

  In addition, the cyclic carbonate which has a fluorine atom expresses an effective function not only as a solvent but also as an auxiliary agent. In the case of using a cyclic carbonate having a fluorine atom as an auxiliary agent, the blending amount is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 1% in 100% by mass of the nonaqueous electrolytic solution. It is at least 5% by mass, preferably at most 5% by mass, more preferably at most 4% by mass, even more preferably at most 3% by mass. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle 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.

<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, n-butyl methyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, t- Examples include 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, chain carbonates 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 blending amount of the chain carbonate is usually 40% by volume or more, preferably 50% by volume or more, more preferably 60% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution is set in an appropriate range, the decrease in ionic conductivity is suppressed, and the large current discharge characteristics of the non-aqueous electrolyte battery are easily set in a favorable range. Further, the chain carbonate is usually 90% by volume or less, preferably 85% by volume or less, in 100% by volume of the non-aqueous solvent. By setting the upper limit in this way, it is easy to avoid a decrease in electrical conductivity resulting from a decrease in dielectric constant of the nonaqueous electrolyte solution, and to make the large current discharge characteristics of the nonaqueous electrolyte solution 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, more preferably 10% by volume or more, in 100% by volume of the non-aqueous solvent. If it is this range, it will become easy to improve the electrical conductivity of a non-aqueous electrolyte solution, and to improve the large current discharge characteristic of a non-aqueous electrolyte battery. Moreover, the compounding quantity of cyclic carboxylic acid ester becomes like this. Preferably it is 50 volume% or less, More preferably, it is 40 volume% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

<Chain carboxylic acid ester>
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 compounding amount of the chain carboxylic acid ester is usually 10% by volume or more, more preferably 15% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte battery are easily improved. Moreover, the compounding quantity of chain | strand-shaped carboxylic acid ester is preferably 60 volume% or less in 100 volume% of non-aqueous solvents, More preferably, it is 50 volume% or less. By setting the upper limit in this way, an increase in negative electrode resistance is suppressed, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte 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, methoxyethoxymethane, methoxy (2 -Fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fur Roethoxy) methane, ethoxy (2,2,2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) ( 2,2,2-trifluoroethoxy) methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2, 2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ) Ethane, methoxy (2,2,2-trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroeth) Xyl) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2 -Fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2, 2,2-trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) Ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, etc. 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 preferably 70% by volume or less, in 100% by volume of the non-aqueous solvent. More preferably, it is 60 volume% or less, More preferably, it is 50 volume% or less. If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall, and when a negative electrode active material is a carbonaceous material, a chain ether with lithium ion It is easy to avoid a situation where the capacity is reduced due to co-insertion.

<Sulfone compound>
As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.
Examples of the cyclic sulfone having 3 to 6 carbon atoms include trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones as monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, hexamethylene disulfones as disulfone compounds, and the like. Is mentioned. 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-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output.

Examples of the chain sulfone having 2 to 6 carbon atoms include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone. , Diisopropylsulfone, n-butylmethylsulfone, n-butylethylsulfone, t-butylmethylsulfone, t-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone , Difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone Ethyl trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n- Propylsulfone, trifluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propyl Sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl- - butyl sulfone, pentafluoroethyl -n- butyl sulfone, pentafluoroethyl -t- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl 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 preferred because high high output ionic conductivity.

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

  These may be used alone or in combination of two or more, but it is preferable to use in combination of two or more. For example, by combining a high dielectric constant solvent such as a cyclic carbonate, a cyclic carbonate having a fluorine atom, or a cyclic carboxylate with a low viscosity solvent such as a chain carbonate or a chain carboxylate at a specific blending amount, battery performance Can be remarkably improved.

  One preferable combination of the non-aqueous solvents 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. When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent may be improved.

  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 thereof include methyl carbonate, ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  A combination in which propylene carbonate is further added to the combination of these ethylene carbonates and chain carbonates is also a preferable combination. In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Furthermore, the proportion of propylene carbonate in the entire non-aqueous solvent is preferably 0.1% by volume or more, more preferably 1% by volume or more, still more preferably 2% by volume or more, and preferably 20% by volume or less, more preferably Is 8% by volume or less, more preferably 5% by volume or less. It is preferable to contain propylene carbonate in this concentration range because the low temperature characteristics may be further improved while maintaining the combination characteristics of ethylene carbonate and dialkyl carbonate.

  Among the combinations of ethylene carbonate and chain carbonate, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, especially ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl. Those containing ethylene carbonate, symmetric chain carbonates, and asymmetric chain carbonates such as methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferred because of a good balance between cycle characteristics and large current discharge characteristics. Among them, the asymmetric chain carbonate is preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

  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, particularly 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.

  When diethyl carbonate is contained in the non-aqueous solvent, the proportion of diethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and further preferably 25% by volume or more. In particular, it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. And gas generation during high temperature storage may be suppressed.

  Further, when dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and further preferably 25% by volume or more. In particular, it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. As a result, 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 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more. 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, sulfur-containing organic solvents, phosphorus-containing organic solvents, aromatic fluorine-containing solvents and the like may be mixed.

Another example of a preferable non-aqueous solvent is that one organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, or a mixed solvent consisting of two or more organic solvents selected from the group is used as the whole. It occupies 60 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 the present 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) The non-aqueous electrolyte solution of the present invention contains an electrolyte and a non-aqueous solvent that dissolves the electrolyte in the same manner as a general non-aqueous electrolyte solution. It contains the compound represented by (1).

<Compound represented by the general formula (1)>
The compound according to the present invention is represented by the following general formula (1).

(R ^{1 to} R ³ each independently represent hydrogen that may be the same or different, or a hydrocarbon group having 1 to 6 carbon atoms. N represents an integer of 4 to 8. A represents carbon. (It represents an organic group that may have a heteroelement of 1 to 12)

Since the compound represented by the general formula (1) has a carbon-carbon double bond, it is reduced at a potential less than the potential for reductive decomposition of the solvent to form a stable negative electrode SEI on the negative electrode. If there is at least one compound selected from the group consisting of a fluorine-substituted oxoacid salt, an aromatic-containing carbonate, and a compound having an isocyanato group at that time, reduction of these and the compound represented by the general formula (1) It is presumed that the decomposition product reacts to form a composite negative electrode SEI. Since the composite negative electrode SEI formed in this way is strong, it is considered that the initial irreversible capacity can be suppressed.

R ^{1 to} R ³ each independently represent hydrogen which may be the same or different, or a hydrocarbon group having 1 to 6 carbon atoms. The hydrocarbon group represents a functional group composed of atoms selected from the group consisting of carbon atoms or hydrogen atoms. R ^{1 to} R ³ are hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, preferably a hydrocarbon group having 4 or less carbon atoms, more preferably a hydrocarbon group having 2 or less carbon atoms. If it is the range, there is little steric hindrance and the film can be stabilized.

  Preferred hydrocarbon groups include a hydrogen group, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, and t-butyl group. The organic group represents a functional group composed of atoms selected from the group consisting of carbon atoms or hydrogen atoms, and the organic group which may have a hetero element refers to carbon atoms, hydrogen atoms, nitrogen atoms Represents a functional group composed of one or more atoms selected from the group consisting of phosphorus atom, boron atom, sulfur atom, silicon atom and oxygen atom.

  Specific examples of the organic group which may have a heteroelement having 1 to 12 carbon atoms represented by A include an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof , Cycloalkenylene group or derivative thereof, arylene group or derivative thereof, carbonyl group or derivative thereof, sulfonyl group or derivative thereof, sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amino group or derivative thereof, Examples thereof include an amide group or a derivative thereof, an imide group or a derivative thereof, an ether group or a derivative thereof, a thioether group or a derivative thereof, a borinic acid group or a derivative thereof, a borane group or a derivative thereof. A derivative represents a functional group substituted with a halogen atom, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, or an alkoxy group.

Among these, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, an arylene group or a derivative thereof, an ether group or a derivative thereof is preferable from the viewpoint of improving battery characteristics. The carbon number of A is 1 or more, preferably 4 or more, and more preferably 5 or more. Moreover, it is 12 or less, 11 or less are preferable and 10 or less are more preferable. Within this range, an increase in resistance can be suppressed while maintaining oxidation resistance. The lower limit of n is 4 or more, while the upper limit is 8 or less, preferably 7 or less, more preferably 6 or less. If it is this range, stable negative electrode SEI can be formed and interface resistance does not rise too much.
Preferable specific examples of the compound represented by the general formula (1) include the following compounds.

  In order to increase the degree of molecular freedom and suppress the resistance of the produced negative electrode SEI, the following structures are more preferable.

  The compound represented by General formula (1) may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. There is no restriction | limiting in the compounding quantity of the compound represented by General formula (1) with respect to the whole nonaqueous electrolyte solution of this invention, and it is arbitrary unless the effect of this invention is impaired remarkably, With respect to the nonaqueous electrolyte solution of this invention Usually, 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and usually 5% by mass or less, preferably 4% by mass or less, more preferably 2% by mass. It is contained at the following concentrations. When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

At this time, it is preferable that the compound represented by the general formula (1) is purified in advance within a range that does not significantly reduce the productivity, and a compound having as few impurities as possible is used.
1-4. Additional compounds other than the compound represented by the general formula (1) In the non-aqueous electrolyte battery of the present invention, together with the compound represented by the general formula (1), a fluorine-substituted oxoacid salt, an aromatic-containing carbonate ester, And at least one compound selected from the group consisting of compounds represented by formula (2).

<Fluorine-substituted oxo acid salt>
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 represented by the general formula (1), fluorine substitution It is more effective to use an oxo acid salt.

The fluorine-substituted oxo acid salt is not particularly limited as long as it is an oxo acid salt having a fluorine atom, and any fluorine-substituted oxo acid salt can be used.
Examples of the fluorine-substituted oxo acid salts include fluorine-substituted carboxylates, fluorine-substituted sulfonates, fluorine-substituted sulfates, and fluorine-substituted phosphates.
The counter cation of the fluorine-substituted oxo acid salt is not particularly limited, but lithium, sodium, potassium, magnesium, calcium, and NR ⁷ R ⁸ R ⁹ R ¹⁰ (wherein R ^{7 to} R ¹⁰ are each independently , Represents a hydrogen atom or an organic group having 1 to 12 carbon atoms).

Although it does not specifically limit as a C1-C12 organic group represented by R < ⁷ > -R < ¹⁰ > of the said ammonium, For example, it is substituted by the alkyl group, the halogen atom, or the alkyl group which may be substituted by the halogen atom. Examples thereof include an cycloalkyl group which may be substituted, an aryl group which may be substituted with a halogen atom or an alkyl group, and a nitrogen atom-containing heterocyclic group which may have a substituent. Among these, as R ^{7 to} R ¹⁰ , a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group is preferable.
Among the counter cations, lithium is most preferable from the viewpoint of resistance to lithium electrodeposition and oxidation.

  Fluoro-substituted carboxylates include fluoroformate, monofluoroacetate, difluoroacetate and trifluoroacetate. Specific examples include lithium fluoroformate, lithium monofluoroacetate, lithium difluoroacetate, and lithium trifluoroacetate.

Examples of the fluorine-substituted sulfonates include trifluoromethane sulfonate and pentafluoroethane sulfonate. Specific examples include lithium fluorosulfonate, lithium trifluoromethanesulfonate, and lithium pentafluoroethanesulfonate. Examples of the fluorine-substituted sulfates include trifluoromethyl sulfate and pentafluoroethyl sulfate. Specific examples include fluorosulfate, lithium trifluoromethyl sulfate, and lithium pentafluoroethyl sulfate. Examples of the fluorine-substituted phosphates include monofluorophosphate and difluorophosphate. Specific examples include lithium monofluorophosphate and lithium difluorophosphate.

  Among them, particularly preferred fluorine-substituted oxoacid salts for use in combination with the compound represented by the general formula (1) are lithium fluorosulfate and lithium difluorophosphate, which form a stable interfacial protective film, and thus more preferably. Used.

  Fluorine-substituted oxo acid salts may be used alone or in combination of two or more in any combination and ratio. The blending amount of the fluorine-substituted oxo acid salt is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. In 100% by mass of the non-aqueous electrolyte, preferably 0.001% by mass or more, more preferably Is 0.01% by mass or more, more preferably 0.1% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. Within this range, the non-aqueous electrolyte battery tends to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics deteriorate, the amount of gas generated increases, and the discharge capacity maintenance ratio decreases. Easy to avoid.

<Aromatic-containing carbonate>
In the non-aqueous electrolyte solution 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 represented by the general formula (1), aromatic It is more effective to use the carbonate ester.
Examples of the aromatic-containing carbonate include compounds represented by the following general formula (3).

(In General Formula (3), Ra represents an alkyl group or aryl group having 1 to 12 carbon atoms which may have a halogen atom. Rb to Rf each independently represent a hydrogen atom or a halogen atom. Represents.)

  The number of carbon atoms of the alkyl group or aryl group represented by Ra is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. From the viewpoint of improving safety during overcharge and battery characteristics, the lower limit is Usually one or more. On the other hand, the upper limit is usually 12 or less, preferably 8 or less, more preferably 6 or less, from the viewpoints of improvement in safety during overcharge, battery characteristics, and solubility in the electrolyte. Examples of the halogen atom that can be substituted with the alkyl group or aryl group represented by Ra include a fluorine atom, a chlorine atom, and a bromine atom. Among these, a fluorine atom is preferable from the viewpoint of battery characteristics.

  Examples of the alkyl group or aryl group having 1 to 12 carbon atoms represented by Ra include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, t-amyl group, 1,1-dimethylbutyl group, cyclohexyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, phenyl group, 2-methylphenyl group, 3-methyl Phenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2-t-butylphenyl group, 3-t-butylphenyl group, 4-t-butylphenyl group , 2-cyclohexylphenyl group, 3-cyclohexylphenyl group, 4-cyclohexylphenyl group, and the like. In these alkyl groups or aryl groups, some or all of the hydrogen atoms may be substituted with fluorine atoms.

Rb to Rf represent a hydrogen atom or a halogen atom. Among these, Rb to Rf are preferably hydrogen atoms from the viewpoint of improving safety during overcharge and battery characteristics.
Examples of the halogen atom represented by Rb to Rf include a fluorine atom, a chlorine atom, and a bromine atom. Among these, a fluorine atom is preferable from the viewpoint of battery characteristics.

Specific examples of the compound represented by the general formula (3) include the following.
Methylphenyl carbonate, methyl-2-methylphenyl carbonate, methyl-3-methylphenyl carbonate, methyl-4-methylphenyl carbonate, 2-ethylphenylmethyl carbonate, 3-ethylphenylmethyl carbonate, 4-ethylphenylmethyl carbonate, 2 -T-butylphenyl methyl carbonate, 3-t-butylphenyl methyl carbonate, 4-t-butylphenyl methyl carbonate, 2-cyclohexylphenyl methyl carbonate, 3-cyclohexylphenyl methyl carbonate,
4-cyclohexylphenylmethyl carbonate, ethylphenyl carbonate, ethyl-2-methylphenyl carbonate, ethyl-3-methylphenyl carbonate, ethyl-4-methylphenyl carbonate, ethyl-2-ethylphenyl carbonate, ethyl-3-ethylphenyl carbonate , Ethyl-4-ethylphenyl carbonate, 2-t-butylphenyl ethyl carbonate,

3-t-butylphenyl ethyl carbonate, 4-t-butylphenyl ethyl carbonate, 2-cyclohexyl phenyl ethyl carbonate, 3-cyclohexyl phenyl ethyl carbonate, 4-cyclohexyl phenyl ethyl carbonate, phenyl-n-propyl carbonate, 2-methylphenyl -N-propyl carbonate, 3-methylphenyl-n-propyl carbonate, 4-methylphenyl-n-propyl carbonate, 2-ethylphenyl-n-propyl carbonate, 3-ethylphenyl-n-propyl carbonate, 4-ethylphenyl -N-propyl carbonate, 2-t-butylphenyl-n-propyl carbonate, 3-t-butylphenyl-n-propyl carbonate, 4-t-butylphenyl-n-pro Le carbonate, 2-phenyl -n- propyl carbonate, 3-phenyl -n- propyl carbonate, 4-phenyl -n- propyl carbonate,

Phenyl-i-propyl carbonate, 2-methylphenyl-i-propyl carbonate, 3-methylphenyl-i-propyl carbonate, 4-methylphenyl-i-propyl carbonate, 2-ethylphenyl-i-propyl carbonate, 3-ethyl Phenyl-i-propyl carbonate, 4-ethylphenyl-i-propyl carbonate, 2-t-butylphenyl-i-propyl carbonate, 3-t-butylphenyl-i-propyl carbonate, 4-t-butylphenyl-i- Propyl carbonate, 2-cyclohexylphenyl-i-propyl carbonate, 3-cyclohexylphenyl-i-propyl carbonate, 4-cyclohexylphenyl-i-propyl carbonate, n-butylphenyl carbonate, n-butyl 2-methylphenyl carbonate, n- butyl-3-methyl phenyl carbonate, n- butyl-4-methylphenyl carbonate, n- butyl-2-ethyl-phenyl carbonate,

n-butyl-3-ethylphenyl carbonate, n-butyl-4-ethylphenyl carbonate, n-butyl-2-t-butylphenyl carbonate, n-butyl-3-t-butylphenyl carbonate, n-butyl-4- t-butylphenyl carbonate, n-butyl-2-cyclohexylphenyl carbonate, n-butyl-3-cyclohexylphenyl carbonate, n-butyl-4-cyclohexylphenyl carbonate, i-butylphenyl carbonate, i-butyl-2-methylphenyl Carbonate, i-butyl-3-methylphenyl carbonate, i-butyl-4-methylphenyl carbonate, i-butyl-2-ethylphenyl carbonate, i-butyl-3-ethylphenyl carbonate, i-butyl-4-ethylphenol Le carbonate, i- butyl -2-t-butyl phenyl carbonate, i- butyl -3-t-butyl phenyl carbonate, i- butyl -4-t-butyl phenyl carbonate,

i-butyl-2-cyclohexylphenyl carbonate, i-butyl-3-cyclohexylphenyl carbonate, i-butyl-4-cyclohexylphenyl carbonate, sec-butylphenyl carbonate, sec-butyl-2-methylphenyl carbonate, sec-butyl- 3-methylphenyl carbonate, sec-butyl-4-methylphenyl carbonate, sec-butyl-2-ethylphenyl carbonate, sec-butyl-3-ethylphenyl carbonate, sec-butyl-4-ethylphenyl carbonate, sec-butyl- 2-t-butylphenyl carbonate, sec-butyl-3-t-butylphenyl carbonate, sec-butyl-4-t-butylphenyl carbonate, se
c-butyl-2-cyclohexyl phenyl carbonate, sec-butyl-3-cyclohexyl phenyl carbonate, sec-butyl-4-cyclohexyl phenyl carbonate, t-butylphenyl carbonate,

t-butyl-2-methylphenyl carbonate, t-butyl 3-methylphenyl carbonate, t-butyl-4-methylphenyl carbonate, t-butyl-2-ethylphenyl carbonate, t-butyl-3-ethylphenyl carbonate, t -Butyl-4-ethylphenyl carbonate, t-butyl-2-t-butylphenyl carbonate, t-butyl-3-t-butylphenyl carbonate, t-butyl-4-t-butylphenyl carbonate, t-butyl-2 -Cyclohexyl phenyl carbonate, t-butyl-3-cyclohexyl phenyl carbonate, t-butyl-4-cyclohexyl phenyl carbonate, n-pentyl-n-pentyl carbonate, 2-methylphenyl-n-pentyl carbonate, 3-methylphenyl n- pentyl carbonate, 4-methylphenyl -n- pentyl carbonate, 2-ethylphenyl -n- pentyl carbonate, 3-ethylphenyl -n- pentyl carbonate,

4-ethylphenyl-n-pentyl carbonate, 2-t-butylphenyl-n-pentyl carbonate, 3-t-butylphenyl-n-pentyl carbonate, 4-t-butylphenyl-n-pentyl carbonate, 2-cyclohexylphenyl -N-pentyl carbonate, 3-cyclohexylphenyl-n-pentyl carbonate, 4-cyclohexylphenyl-n-pentyl carbonate, t-amylphenyl carbonate, t-amyl-2-methylphenyl carbonate, t-amyl-3-methylphenyl Carbonate, t-amyl-4-methylphenyl carbonate, t-amyl-2-ethylphenyl carbonate, t-amyl-3-ethylphenyl carbonate, t-amyl-4-ethylphenyl carbonate, t-amyl- -T-butylphenyl carbonate, t-amyl-3-t-butylphenyl carbonate, t-amyl-4-t-butylphenyl carbonate, t-amyl-2-cyclohexylphenyl carbonate, t-amyl-3-cyclohexylphenyl carbonate ,

t-amyl-4-cyclohexylphenyl carbonate, 1,1-dimethylbutylphenyl carbonate, 1,1-dimethylbutyl-2-methylphenyl carbonate, 1,1-dimethylbutyl-3-methylphenyl carbonate, 1,1-dimethyl Butyl-4-methylphenyl carbonate, 1,1-dimethylbutyl-2-ethylphenyl carbonate, 1,1-dimethylbutyl-3-ethylphenyl carbonate, 1,1-dimethylbutyl-4-ethylphenyl carbonate, 2-t -Butylphenyl-1,1-dimethylbutyl carbonate, 3-t-butylphenyl-1,1-dimethylbutyl carbonate, 4-t-butylphenyl-1,1-dimethylbutyl carbonate, 2-cyclohexylphenyl-1,1 -Dimethylbutylcar Sulfonate, 3-phenyl-1,1-dimethyl-butyl carbonate, 4-phenyl-1,1-dimethyl-butyl carbonate, cyclohexyl phenyl carbonate,

Cyclohexyl-2-methylphenyl carbonate, cyclohexyl-3-methylphenyl carbonate, cyclohexyl-4-methylphenyl carbonate, cyclohexyl-2-ethylphenyl carbonate, cyclohexyl-3-ethylphenyl carbonate, cyclohexyl-4-ethylphenyl carbonate, 2- t-butylphenylcyclohexyl carbonate, 3-t-butylphenylcyclohexyl carbonate, 4-t-butylphenylcyclohexyl carbonate, cyclohexyl-2-cyclohexylphenyl carbonate, cyclohexyl-3-cyclohexylphenyl carbonate, cyclohexyl-4-cyclohexylphenyl carbonate, 1 -Methylcyclohexyl phenyl carbonate, 1-methyl Hexyl-2-methyl phenyl carbonate, 1-methyl-cyclohexyl-3-methyl phenyl carbonate, 1-methyl-cyclohexyl-4-methyl phenyl carbonate,

2-ethylphenyl-1-methylcyclohexyl carbonate, 3-ethylphenyl-1-methylcyclohexyl carbonate, 4-ethylphenyl-1-methylcyclohexyl carbonate, 2-t-butylphenyl-1-methylcyclohexyl carbonate, 3-t- Butylphenyl-1-methylcyclohexyl carbonate, 4-t-butylphenyl-1-methylcyclohexyl carbonate, 2-cyclohexylphenyl-1-methylcyclohexyl carbonate, 3-cyclohexylphenyl-1-methylcyclohexyl carbonate, 4-cyclohexylphenyl-1 -Methylcyclohexyl carbonate, 1-ethylcyclohexylphenyl carbonate, 1-ethylcyclohexyl-2-methylphenyl carbonate, 1- Tylcyclohexyl 3-methylphenyl carbonate, 1-ethylcyclohexyl-4-methylphenyl carbonate, 1-ethylcyclohexyl-2-ethylphenyl carbonate, 1-ethylcyclohexyl-3-ethylphenyl carbonate, 1-ethylcyclohexyl-4-ethylphenyl Carbonate,

2-t-butylphenyl 1-ethylcyclohexyl carbonate, 3-t-butylphenyl-1-ethylcyclohexyl carbonate, 4-t-butylphenyl-1-ethylcyclohexyl carbonate, 2-cyclohexylphenyl-1-ethylcyclohexyl carbonate, 3 -Cyclohexylphenyl-1-ethylcyclohexyl carbonate, 4-cyclohexylphenyl-1-ethylcyclohexyl carbonate, diphenyl carbonate, 2-methylphenylphenyl carbonate, 3-methylphenylphenyl carbonate, 4-methylphenylphenyl carbonate, 2-ethylphenylphenyl Carbonate, 3-ethylphenylphenyl carbonate, 4-ethylphenylphenyl carbonate, 2-t-butylpheny Phenyl carbonate, 3-t-butylphenyl phenyl carbonate, 4-t-butylphenyl phenyl carbonate, 2-cyclohexyl phenyl carbonate,

3-cyclohexylphenylphenyl carbonate, 4-cyclohexylphenylphenyl carbonate, bis-2-methylphenyl carbonate, 2-methylphenyl-3-methylphenyl carbonate, 2-methylphenyl-4-methylphenyl carbonate, 2-ethylphenyl-2 -Methylphenyl carbonate, 3-ethylphenyl-2-methylphenyl carbonate, 4-ethylphenyl-2-methylphenyl carbonate, 2-t-butylphenyl-2-methylphenyl carbonate, 3-t-butylphenyl-2-methyl Phenyl carbonate, 4-t-butylphenyl-2-methylphenyl carbonate, 2-cyclohexylphenyl-2-methylphenyl carbonate, 3-cyclohexylphenyl-2-methylpheny Carbonate, 4-phenyl-2-methyl phenyl carbonate, bis-3-methyl phenyl carbonate, 3-methylphenyl-4-methyl phenyl carbonate,

2-ethylphenyl-3-methylphenyl carbonate, 3-ethylphenyl-3-methylphenyl carbonate, 4-ethylphenyl-3-methylphenyl carbonate, 2-t-butylphenyl-3-methylphenyl carbonate, 3-t- Butylphenyl-3-methylphenyl carbonate, 4-t-butylphenyl-3-methylphenyl carbonate, 2-cyclohexylphenyl-3-methylphenyl carbonate, 3-cyclohexylphenyl-3-methylphenyl carbonate, 4-cyclohexylphenyl-3 -Methylphenyl carbonate, bis-4-methylphenyl carbonate, 2-ethylphenyl-4-methylphenyl carbonate, 3-ethylphenyl-4-methylphenyl carbonate, 4-ethylphenyl- - methyl phenyl carbonate, 2-t-butylphenyl-4-methyl phenyl carbonate, 3-t-butylphenyl-4-methyl phenyl carbonate, 4-t-butylphenyl-4-methyl phenyl carbonate,

2-cyclohexylphenyl-4-methylphenyl carbonate, 3-cyclohexylphenyl-4-methylphenyl carbonate, 4-cyclohexylphenyl-4-methylphenyl carbonate, bis-2-ethylphenyl carbonate, 2-ethylphenyl-3-ethylphenyl Carbonate, 2-ethylphenyl-4-ethylphenyl carbonate, 2-t-butylphenyl-2-ethylphenyl carbonate, 3-t-butylphenyl-2-ethylphenyl carbonate, 4-t-butylphenyl-2-ethylphenyl Carbonate, 2-cyclohexylphenyl-2-ethylphenyl carbonate, 3-cyclohexylphenyl-2-ethylphenyl carbonate, 4-cyclohexylphenyl-2-ethylphenyl carbonate , Bis-3-ethyl phenyl carbonate, 3-ethyl-phenyl-4-ethyl-phenyl carbonate, 2-t-butylphenyl-3-ethyl-phenyl carbonate,

3-t-butylphenyl-3-ethylphenyl carbonate, 4-t-butylphenyl-3-ethylphenyl carbonate, 2-cyclohexylphenyl-3-ethylphenyl carbonate, 3-cyclohexylphenyl-3-ethylphenyl carbonate, 4- Cyclohexylphenyl-3-ethylphenyl carbonate, bis-4-ethylphenyl carbonate, 2-t-butylphenyl-4-ethylphenyl carbonate, 3-t-butylphenyl-4-ethylphenyl carbonate, 4-t-butylphenyl- 4-ethylphenyl carbonate, 2-cyclohexylphenyl-4-ethylphenyl carbonate, 3-cyclohexylphenyl-4-ethylphenyl carbonate, 4-cyclohexylphenyl-4-ethylphenyl carbonate Boneto, bis -2-t-butyl phenyl carbonate, 2-t-butylphenyl -3-t-butyl phenyl carbonate, 2-t-butylphenyl -4-t-butyl phenyl carbonate,

2-t-butylphenyl-2-cyclohexylphenyl carbonate, 2-t-butylphenyl-3-cyclohexylphenyl carbonate, 2-t-butylphenyl-4-cyclohexylphenyl carbonate, bis-3-t-butylphenyl carbonate, 3 -T-butylphenyl-4-t-butylphenyl carbonate, 3-t-butylphenyl-2-cyclohexylphenyl carbonate, 3-t-butylphenyl-3-cyclohexylphenyl carbonate, 3-t-butylphenyl-4-cyclohexyl Phenyl carbonate, bis-4-t-butylphenyl carbonate, 4-t-butylphenyl-2-cyclohexylphenyl carbonate, 4-t-butylphenyl-3-cyclohexylphenyl carbonate, 4-t-butyl Ruphenyl-4-cyclohexylphenyl carbonate, bis-2-cyclohexylphenyl carbonate, 2-cyclohexylphenyl-3-cyclohexylphenyl carbonate, 2-cyclohexylphenyl-4-cyclohexylphenyl carbonate, bis-3-cyclohexylphenyl carbonate, 3-cyclohexylphenyl -4-Cyclohexylphenyl carbonate and bis-4-cyclohexylphenyl carbonate are more preferable. Since these compounds have high oxidation resistance and are not easily oxidized and decomposed in the range of voltages normally used, good battery characteristics can be obtained.

Methyl phenyl carbonate, ethyl phenyl carbonate, n-propyl phenyl carbonate, i-propyl phenyl carbonate, n-butyl phenyl carbonate, i-butyl phenyl carbonate, sec-butyl phenyl carbonate, t-butyl phenyl carbonate, n-pentyl phenyl carbonate, t-Amylphenyl carbonate, (1,1-dimethylbutyl) phenyl carbonate, and diphenyl carbonate are more preferable. These compounds have higher oxidation resistance and are less susceptible to oxidative decomposition within the range of voltages normally used, so that better battery characteristics can be obtained.
Methyl phenyl carbonate, ethyl phenyl carbonate, n-propyl phenyl carbonate, n-butyl phenyl carbonate and diphenyl carbonate are particularly preferred. These compounds have particularly high oxidation resistance, and are particularly difficult to oxidize in the range of voltages normally used, so that even better battery characteristics can be obtained.

  The ratio of the compound represented by the general formula (3) in the nonaqueous electrolytic solution is not particularly limited, and is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.001% by mass or more, preferably 0. 0.01 mass% or more, more preferably 0.05 mass% or more, and particularly preferably 0.1 mass% or more. The upper limit is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass, particularly preferably 2% by mass or less, and most preferably 1.5% by mass or less. Within this range, adverse effects due to oxidative decomposition can be suppressed, and an increase in the viscosity of the electrolytic solution can be suppressed. Therefore, good battery characteristics can be obtained in the range of normally used voltages.

<Compound represented by formula (2)>
In the non-aqueous electrolyte solution 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 represented by the general formula (1), the general formula Use of the compound represented by (2) is more effective.

(R ⁶ represents an organic group which may have a heteroelement having 1 to 12 carbon atoms, and may be the same or different. M represents an integer of 1 to 6, and n1 and n2 are 0. Or, when n1 is 1, n2 is 0, and when n2 is 1, n1 is 0. R ⁶ may be bonded to form a ring.
R ⁶ has 1 or more and 12 or less carbon atoms, preferably 2 or more and 11 or less, and more preferably 3 or more and 10 or less. Within this range, oxidative decomposition hardly occurs, and a stable negative electrode SEI can be formed when reacting with the negative electrode.
Examples of the organic group which may have a heteroelement having 1 to 12 carbon atoms represented by R ⁶ include a methyl group, an ethyl group, a vinyl group, an ethynyl group, an n-propyl group, an i-propyl group, and an allyl group. 2-propynyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, 1-butynyl group, n-pentyl group, t-amyl group, 1,1-dimethylbutyl group, cyclohexyl Group, phenyl group, or the following structure.

  Among these substituents, an allyl group, a 2-propynyl group, or a substituent represented by the following structure is preferable because a more stable negative electrode SEI can be formed.

When R ⁶ is bonded to form a ring, the number of carbon atoms is usually 1 or more, preferably 2 or more, more preferably 3 or more, and usually 6 or less, preferably 5 or less, more preferably 4 or less. . Within this range, a stable negative electrode SEI can be formed when reacting with the negative electrode.
Examples of the structure in which R ⁶ are bonded to form a ring include methylene, ethylene, trimethylene and tetramethylene. Among these substituents, methylene and ethylene are preferable because of high reaction activity in the negative electrode.
Specific examples of the compound represented by the general formula (2) include the following.

  From the viewpoint of oxidation resistance and stability of the negative electrode SEI, the following structures are more preferable.

  The compound represented by General formula (2) may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. The compounding amount of the compound represented by the general formula (2) with respect to the entire non-aqueous electrolyte solution of the present invention is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired, but with respect to the non-aqueous electrolyte solution of the present invention. In general, it is 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 or less, preferably 4% by mass or less, more preferably 2% by mass. It is contained at the following concentrations. When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-5. Auxiliary Agent In the non-aqueous electrolyte battery of the present invention, an auxiliary agent may be appropriately used depending on the purpose in addition to the compound represented by the general formula (1) and the above compound. As an auxiliary agent, the cyclic carbonate which has the carbon-carbon unsaturated bond shown below, the unsaturated cyclic carbonate which has a fluorine atom, an overcharge inhibitor, and another auxiliary agent are mentioned. Among these, since it is excellent in the balance between the suppression effect of side reaction between the electrode active material and the electrolyte and the increase in battery resistance, the cyclic carbonate having a carbon-carbon unsaturated bond, the unsaturated cyclic carbonate having a fluorine atom Is preferred.

<Cyclic carbonate having a carbon-carbon 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 represented by the general formula (1), carbon- It is more effective to use a cyclic carbonate having a carbon unsaturated bond (hereinafter sometimes abbreviated as “unsaturated cyclic carbonate”).

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 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, phenyl carbonates, vinyl carbonates, and allyl carbonates.

Examples of vinylene carbonates include vinylene carbonate (hereinafter sometimes abbreviated as VC), methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate,
Examples thereof include 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, preferable unsaturated cyclic carbonates for use in combination with the compound represented by the general formula (1) include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, and 4,5-vinyl. Vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4 -Methyl-5-allylethylene carbonate and 4-allyl-5-vinylethylene carbonate are more preferably used because they form a stable interface protective film.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 86 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily. The molecular weight of the unsaturated cyclic carbonate is more preferably 150 or less. The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.

  An unsaturated cyclic carbonate may be used individually by 1 type, or may 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 amount of the unsaturated cyclic carbonate is 100% by mass in the non-aqueous electrolyte solution, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more. Further, it is preferably 10% by mass or less, more preferably 7% by mass or less, and further preferably 5% by mass or less.

Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improving 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. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.

<Unsaturated cyclic carbonate having a fluorine atom>
As the unsaturated cyclic carbonate having a fluorine atom, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes abbreviated as “fluorinated unsaturated cyclic carbonate”) is also preferably used. 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 fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with an aromatic ring or a substituent having a carbon-carbon double bond.
Fluorinated vinylene carbonate derivatives include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

  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, particularly preferred fluorinated unsaturated cyclic carbonates for use in combination with the compound represented by the general formula (1) include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5- Vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-4-vinyl ethylene carbonate, 4-fluoro-4-allyl ethylene carbonate, 4-fluoro-5-vinyl ethylene 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, -Fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate However, since it forms a stable interface protective film, it is more preferably used.

The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 86 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the fluorinated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the fluorinated unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 150 or less.

  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 in 100% by mass of the non-aqueous electrolyte solution, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass. Further, it is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.

<Overcharge prevention agent>
In the non-aqueous electrolyte solution of the present invention, an overcharge inhibitor can be used in order to effectively prevent the battery from bursting or igniting when the non-aqueous electrolyte battery is overcharged.
As an overcharge inhibitor, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran; 2-fluorobiphenyl, Partially fluorinated products of the above aromatic compounds such as o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole and the like And a fluorine-containing anisole compound. Of these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable. These may be used alone or in combination of two or more. When two or more kinds are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, Using at least one selected from aromatic compounds not containing oxygen, such as t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether, dibenzofuran, and the like is an overcharge prevention property and a high temperature storage property. From the standpoint of balance.

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

<Other auxiliaries>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, anhydrous Carboxylic anhydrides such as itaconic acid, diglycolic anhydride, cyclohexanedicarboxylic anhydride, and phenylsuccinic anhydride; 2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-divinyl Spiro compounds such as -2,4,8,10-tetraoxaspiro [5.5] undecane; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3 -Nitrogen-containing compounds such as dimethyl-2-imidazolidinone and N-methylsuccinimide ; Heptane, octane, nonane, decane, hydrocarbon compounds cycloheptane, etc., fluorobenzene, difluorobenzene, hexafluorobenzene, fluorinated aromatic compounds such as benzotrifluoride, and the like. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

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

1-6. Gelling agent When used in the lithium secondary battery of the present invention, the gelling agent may exist in a liquid state, which may be gelled with a polymer to form a semi-solid electrolyte. From the viewpoint of improving rate characteristics, a liquid state is preferable.
The polymer used for the gelation is arbitrary, and examples thereof include polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyethylene oxide, polyacrylate, and polymethacrylate. In addition, the polymer | macromolecule used for gelatinization may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Moreover, when using a non-aqueous electrolyte as a semi-solid electrolyte, the ratio of the non-aqueous electrolyte in the semi-solid electrolyte is arbitrary as long as the effects of the present invention are not significantly impaired. As a suitable range, the ratio of the non-aqueous electrolyte to the total amount of the semisolid electrolyte is usually 30% by mass or more, preferably 50% by mass or more, more preferably 75% by mass or more, and usually 99.95% by mass. Hereinafter, it is preferably 99% by mass or less, more preferably 98% by mass or less. When the ratio of the non-aqueous electrolyte is 30% by mass or more, charge and discharge efficiency and capacity are sufficient, and when it is 99.95% by mass or less, it is difficult to hold the electrolyte and liquid leakage occurs. Is suppressed.

  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 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 electrolysis of the present invention described above. Liquid.

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 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 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 is particularly preferable because of a good balance.

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, and further preferably 30 μm or less.
5 μm or less is particularly preferable.

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, a non-uniform 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 carbon powder in a 0.2% by weight aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This 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.

Further, the Raman half-value width of the near 1580 cm ^-1 of the carbonaceous material is not particularly limited, is generally 10 cm ^-1 or more, preferably 15cm ^-1 or more, and is generally 100 cm ^-1 or less, is 80 cm ^-1 or less Preferably, it is more preferably 60 cm ⁻¹ or less, and particularly preferably 40 cm ⁻¹ or less.
The Raman R value and the Raman half width are indices indicating the crystallinity of the surface of the carbonaceous material, but the carbonaceous material has appropriate crystallinity from the viewpoint of chemical stability, and Li enters through charge and discharge. It is preferable that the crystallinity is such that the sites between the layers are not lost, that is, the charge acceptability is not lowered. In the case where the density of the negative electrode is increased by press after applying to the current collector, it is preferable to take account of this because crystals tend to be oriented in a direction parallel to the electrode plate. When the Raman R value or the Raman half width is in the above range, a suitable film can be formed on the negative electrode surface to improve the storage characteristics, cycle characteristics, and load characteristics, and the efficiency associated with the reaction with the nonaqueous electrolyte solution Reduction and gas generation can be suppressed.

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

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half width analysis: Background processing ・ Smoothing processing: 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 is more preferable, 1.5 m ² · g ⁻¹ or more is particularly preferable, and usually 100 m.
And a ² · ^{g -1} or less, preferably ^{25 m} 2 · ^{g -1} or less, ^{15 m} 2 · ^{g -1} and more preferably less, ^{10 m} 2 · ^{g -1} or less are especially preferred.

When the value of the BET specific surface area is in the above range, precipitation of lithium on the electrode surface can be suppressed, while gas generation due to reaction with the non-aqueous electrolyte can be suppressed.
The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately prepared so that the value of the relative pressure is 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material of the present invention.

(Roundness)
When the circularity is measured as the degree of the sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere. The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. As the high current density charge / discharge characteristics are larger, the filling property is improved and the resistance between the particles can be suppressed as the circularity is larger, so that the high current density charge / discharge characteristics are improved. Therefore, it is preferable that the circularity is as high as the above range.

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

  The method for improving the circularity is not particularly limited, but a sphere-shaped sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, 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 in the above range, battery capacity can be ensured and increase in resistance between particles can be suppressed.

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

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

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

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

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

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

<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 a 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 current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.
In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.
The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less, from the viewpoint of securing battery capacity and handling properties.

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

(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 to the negative electrode active material is within the above range, the battery capacity and the strength of the negative electrode can be sufficiently secured.

  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, 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, dimethylacetamide, 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 in the above range, it is possible to suppress a decrease in battery capacity and an increase in resistance, and it is possible to ensure good coatability.

(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 is in the above range, the negative electrode active material particles are prevented from being destroyed, and an increase in initial irreversible capacity or to the vicinity of the current collector / negative electrode active material interface. While the deterioration of the high current density charge / discharge characteristics due to the reduced permeability of the non-aqueous electrolyte solution can be suppressed, the decrease in battery capacity and the increase in resistance can be suppressed.

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

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

2-2. Positive electrode <Positive electrode active material>
The positive electrode active material 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 _0.10 Al _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 elements.

  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 used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. %, And 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. If it is too high, the resistance may increase in order to inhibit the entry and exit of lithium ions.
In the present invention, a material in which a material having a composition different from that of the positive electrode active material is attached to the surface of the positive electrode active material is also referred to as a “positive electrode active material”.

(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. When the tap density of the positive electrode active material is within the above range, it is possible to suppress the amount of dispersion medium and the necessary amount of conductive material and binder required when forming the positive electrode active material layer. Capacity can be secured. 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. However, the tap density is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and further preferably 3.5 g / cm ³ or less. When it is within the above range, it is possible to suppress a decrease in load characteristics.
In the present invention, the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.

(Median diameter d50)
The median diameter d50 of the positive electrode active material particles (secondary particle diameter when primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably. Is 0.8 μm or more, most preferably 1.0 μm or more, and 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. While being in the above range, a high tap density product can be obtained and the battery performance can be prevented from deteriorating. On the other hand, when forming the positive electrode of the battery, that is, when slurrying the active material, conductive material, binder, etc. with a solvent, Problems such as streaking can be prevented. Here, by mixing two or more kinds of the positive electrode active materials having different median diameters d50, it is possible to further improve the filling property when forming the positive electrode.

  In the present invention, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. 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. When it is in the above range, powder filling property and specific surface area can be secured and deterioration of battery performance can be suppressed, while reversibility of charge and discharge can be secured by obtaining appropriate crystallinity. .

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 0.2 m ² / g or more, still more preferably 0.3 m ² / g or more, and the upper limit is 50 m ² / g or less. , Preferably 40 m ² / g or less, more preferably 30 m ² / g or less. When the BET specific surface area is in the above range, the battery performance can be secured and the applicability of the positive electrode active material can be kept good.

  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. It is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas accurately prepared 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 preparing a spherical or elliptical active material. For example, a transition metal source material is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, and dried as necessary. Then, a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ is added, and the active material is obtained by baking at a high temperature. .

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 LiMn ₂ O ₄ such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ or a part of this Mn substituted with another transition metal or the like. Or a combination with LiCoO ₂ or a part of this Co substituted with another transition metal or the like.

<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. Within the above range, the electric capacity of the positive electrode active material in the positive electrode active material layer can be secured, and the strength of the positive electrode can be maintained.
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 , still more preferably 2.2 g / cm ³ or more, and the upper limit is preferably 5 g / cm 3. ^{It is 3} or less, more preferably 4.5 g / cm ³ or less, and further preferably 4 g / cm ³ or less. Within the above range, good charge / discharge characteristics can be obtained, and an increase in electrical resistance can be suppressed.

(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. Sufficient electrical conductivity and battery capacity can be ensured within the above range.

(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 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% 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. The upper limit is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. When it is in the above range, good coatability can be obtained, and a decrease in battery capacity and an increase in resistance can be suppressed.

(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, from the viewpoint of strength and handleability as a current collector, 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, it is 50 μm or less.

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. Within the above range, heat generation of the current collector during high current density charge / discharge can be suppressed, and battery capacity can be secured.

(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. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. Within the above range, insulation and mechanical strength can be secured, while battery performance such as rate characteristics and energy density can be secured.
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. When the porosity is in the above range, insulation and mechanical strength can be secured, while film resistance can be suppressed and good rate characteristics can be obtained.

  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. When the average pore diameter is in the above range, the film resistance can be suppressed and good rate characteristics can be obtained while preventing a short circuit. 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 occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. . When the electrode group occupancy is in the above range, the battery capacity can be secured and the deterioration of characteristics such as charge / discharge repetition performance and high temperature storage accompanying the increase in internal pressure can be suppressed, and further the operation of the gas release valve can be prevented. Can do.

<Current collection structure>
The current collecting structure is not particularly limited, but in order to more effectively realize the high current density charge / discharge characteristics by the non-aqueous electrolyte solution of the present invention, a structure that reduces the resistance of the wiring part and the joint part is used. It is preferable. Thus, when internal resistance is reduced, the effect of using the non-aqueous electrolyte solution of this invention is exhibited especially favorable.

  In the case where the electrode group has the 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 to each other 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 exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<Protective element>
As a protective element, PTC (Positive Temperature Coefficient), thermal fuse, thermistor whose resistance increases when abnormal heat generation or excessive current flows, thermal fuse, thermistor, shuts off the current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature at 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.
[Examples 1 to 4, Comparative Examples 1 to 7]
[Preparation of Negative Electrode] 100 parts by mass of an aqueous dispersion of sodium carboxymethyl cellulose (concentration of 1% by mass of carboxymethyl cellulose sodium) as a thickener and binder, respectively, in 98 parts by mass of a carbonaceous material containing natural graphite as a negative electrode active material And 2 parts by mass of an aqueous dispersion of styrene-butadiene rubber (styrene-butadiene rubber concentration of 50% by mass) were added and mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and rolled with a press. The active material layer was 25 mm wide, 40 mm long, 5 mm wide, and 9 mm long uncoated. It cut out into the shape which has a part, and it was set as the negative electrode used for Examples 1-4 and Comparative Examples 1-7, respectively.

[Production of positive electrode]
90% by mass of nickel-containing metal oxide 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 in an N-methylpyrrolidone solvent Mixed and slurried. The obtained slurry was applied to an aluminum foil having a thickness of 15 μm, dried, and rolled with a press. The active material layer was 25 mm wide, 40 mm long, 5 mm wide, and 9 mm long uncoated. It cut out into the shape which has a process part, and it was set as the positive electrode used by Examples 1-4 and Comparative Examples 1-7, respectively.

[Manufacture of electrolyte]
In a dry argon atmosphere, LiPF6 dried to a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) (volume ratio 15: 5: 80) to a ratio of 1.4 mol / L. After dissolution, vinylene carbonate was mixed so as to be 0.75% by mass to obtain a basic electrolytic solution. The basic electrolyte solution was mixed with the compounds shown in Table 1 to obtain electrolyte solutions used in Examples 1 to 4 and Comparative Examples 1 to 7, respectively. The content here means mass% relative to the total amount of the non-aqueous electrolyte solution.

[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, and the positive electrode to prepare a battery element.
The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and each of the electrolyte solutions shown in Table 1 was placed in the bag. And then sealed in a vacuum to produce sheet batteries, which were used for Examples 1 to 4 and Comparative Examples 1 to 7, respectively.

[Initial irreversible capacity]
The lithium secondary battery is charged with a constant current corresponding to 0.1 C at 25 ° C. with a constant current of 0.2 C at 25 ° C. with a glass plate sandwiched between the electrodes in order to enhance adhesion between the electrodes. After discharging to 2.5V, charging at constant current-constant voltage to 0.05V at 0.2C (0.05C cut), discharging to 2.5V at a constant current of 0.2C was repeated twice. . Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and 0.2C represents a current value of 1/5 thereof. In all three charge / discharge cycles, the difference between the sum of the three charge capacities and the sum of the three discharge capacities is defined as the initial irreversible capacity. This is expressed as a relative value when the initial irreversible capacity of Comparative Example 7 is set to 100. The evaluation results are shown in Table 1.
[Cycle capacity maintenance rate]
After the measurement of the initial irreversible capacity was completed, with a lithium secondary battery sandwiched between glass plates, constant current-constant voltage charging (0.05 C cut) to 4.2 V at 0.8 C at 60 ° C., Discharging to 2.5 V at a constant current of 1 C was repeated 250 times. At this time, a value of (250th discharge capacity / first discharge capacity) × 100 is defined as a cycle capacity maintenance rate.

As is clear from Table 1, the batteries using the non-aqueous electrolyte solution according to the present invention (Examples 1 to 4) are suppressed in the initial irreversible capacity compared to the batteries not containing (Comparative Examples 1 to 7). In addition, it can be seen that the cycle capacity retention rate is improved. For example, when tetramethylolmethane tetraacrylate (Comparative Example 1), lithium difluorophosphate (Comparative Example 3), methylphenyl carbonate (Comparative Example 5), and cyclodison (Comparative Example 6) are added individually, Comparative Example 7 The irreversible capacity is larger than that, and the battery performance is deteriorated. However, in Example 1, Example 3, and Example 4, the irreversible capacity is smaller than in Comparative Examples 1 and 3 to 7, and the battery performance is improved.

According to the non-aqueous electrolyte solution of the present invention, an effect of improving the initial irreversible capacity of the non-aqueous electrolyte secondary battery can be expected.
Therefore, the non-aqueous electrolyte solution of the present invention and the non-aqueous electrolyte secondary battery using the same can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, etc. , Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Backup Power Supply, Motor, Automobile, Motorcycle, Motorbike, Bicycle, Lighting Equipment, Toy, Game Equipment, Clock, Electric Tool, Strobe, Camera, Load Examples include leveling power sources and natural energy storage power sources. Moreover, it can utilize suitably also in the lithium ion capacitor using a non-aqueous electrolyte solution.

Claims (4)

A non-aqueous electrolyte secondary comprising a positive electrode capable of inserting and extracting metal ions, a negative electrode capable of storing and releasing metal ions, and a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent for dissolving the electrolyte A non-aqueous electrolyte used in a battery, wherein the non-aqueous electrolyte contains a compound represented by the following general formula (1), and further includes a fluorine-substituted oxoacid salt, an aromatic-containing carbonate, and a general formula ( 2) A non-aqueous electrolyte containing at least one compound selected from the group consisting of compounds represented by 2).

(R ^{1 to} R ³ each independently represent hydrogen that may be the same or different, or a hydrocarbon group having 1 to 6 carbon atoms. N represents an integer of 4 to 8. A represents carbon. (It represents an organic group that may have a heteroelement of 1 to 12)

(R ⁶ represents an organic group that may have a heteroelement having 1 to 12 carbon atoms, and may be the same or different. M represents an integer of 1 to 6, and n1 and n2 each represent Represents 0 or 1, and when n1 is 0, n2 is 1, and when n1 is 1, n2 is 0. R ⁶ may be bonded to form a ring.   The non-aqueous electrolyte solution according to claim 1, wherein the fluorine-substituted oxoacid salt is at least one selected from the group consisting of difluorophosphate and fluorosulfate.   The nonaqueous electrolyte solution further contains at least one compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom. The non-aqueous electrolyte solution according to any one of the above. 4. A non-aqueous electrolyte battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is a non-aqueous electrolyte solution according to claim 1. A non-aqueous electrolyte secondary battery characterized by the above.