JP5565212B2 - Non-aqueous electrolyte and non-aqueous electrolyte battery using the same - Google Patents

Description

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

  Non-aqueous electrolyte batteries such as lithium secondary batteries are being put to practical use in a wide range of applications from so-called consumer power sources such as mobile phones and laptop computers to in-vehicle power sources for automobiles and the like. However, in recent years, there has been an increasing demand for higher performance for non-aqueous electrolyte batteries, and in particular, improvement of various battery characteristics such as high capacity, high-temperature storage characteristics, and cycle characteristics has been demanded.

  The electrolyte used for a non-aqueous electrolyte battery is usually composed mainly of an electrolyte and a non-aqueous 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, in order to improve battery characteristics such as load characteristics, cycle characteristics, and storage characteristics of such nonaqueous electrolyte batteries, and to improve battery safety during overcharge, various studies have been made on nonaqueous solvents and electrolytes. ing.
Patent Document 1 proposes to protect the battery by increasing the internal resistance of the battery by mixing an additive that is polymerized at a battery voltage equal to or higher than the maximum operating voltage of the battery in the electrolyte. In 2 the internal electrical disconnection device provided for overcharge protection is ensured by mixing an additive that generates gas and pressure by polymerizing in the electrolyte at a battery voltage higher than the maximum operating voltage of the battery. It has been proposed to work. Moreover, aromatic compounds, such as biphenyl, thiophene, and furan, are disclosed as those additives. Further, Patent Document 3 discloses a non-aqueous system in which phenylcyclohexane is added in a range of 0.1 to 20 parts by weight in a non-aqueous electrolyte solution in order to suppress deterioration of battery characteristics when biphenyl or thiophene is used. A non-aqueous electrolyte secondary battery system including an electrolyte secondary battery and a charge control system that senses an increase in battery temperature and disconnects a charging circuit has been proposed.

  In Patent Document 4, in order to improve the cycle characteristics of a non-aqueous electrolyte secondary battery including a negative electrode active material having at least one atom selected from the group consisting of Si atom, Sn atom and Pb atom, non-aqueous electrolysis It has been proposed to contain a carbonate having at least one of an unsaturated bond and a halogen atom in the liquid and a chain compound having a sulfur-containing functional group represented by a specific structure.

  To increase the capacity, for example, pressurize the active material layer of the electrode to increase the density to reduce the volume occupied by the active material other than the active material inside the battery as much as possible. How to do is being studied. However, when the active material layer of the electrode is pressurized and densified, it becomes difficult to use the active material uniformly, and some lithium precipitates due to a non-uniform reaction or deterioration of the active material is promoted. As a result, a problem that sufficient characteristics cannot be obtained easily occurs. Further, when the use range of the positive electrode is expanded to be used up to a high potential, the activity of the positive electrode is further increased, and the problem that the deterioration is accelerated by the reaction between the positive electrode and the electrolytic solution is likely to occur.

Furthermore, since the voids inside the battery are reduced due to the increase in capacity, there is a problem that the internal pressure of the battery is remarkably increased even when a small amount of gas is generated due to the decomposition of the electrolytic solution.
In particular, in non-aqueous electrolyte two batteries, in most cases used as a backup power source in the event of a power failure or as a power source for portable equipment, a weak current is always supplied to make up for the self-discharge of the battery, and the battery is continuously charged. In such a continuously charged state, the activity of the electrode active material is always high, and at the same time, due to the heat generated by the device, the capacity of the battery is reduced, or the electrolyte is decomposed and gas is easily generated. If a large amount of gas is generated, a safety valve may be activated in a battery that senses this when the internal pressure is abnormally increased due to an abnormality such as overcharge and activates the safety valve. Further, in a battery without a safety valve, the battery may expand due to the pressure of the generated gas, and the battery itself may become unusable.

In the non-aqueous electrolyte secondary battery using the electrolyte solution described in Patent Documents 1 to 3, the high-temperature storage characteristics are deteriorated as described above, which is not yet satisfactory.
Further, the non-aqueous electrolyte secondary battery using the electrolyte described in Patent Document 4 is not satisfactory in terms of improving safety during overcharge.

JP-A-9-106835 JP-A-9-171840 JP 2002-50398 A JP 2007-317654 A

  In view of the above problems, an object of the present invention is to provide a non-aqueous electrolyte battery that is excellent in safety during overcharge and high-temperature continuous charge characteristics, and a non-aqueous electrolyte that provides the same.

As a result of various studies to achieve the above object, the present inventors have found that the above problems can be solved by including a compound having a specific structure in the electrolytic solution, thereby completing the present invention. I came to let you.
That is, the gist of the present invention is as follows.
(1) In a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent, the non-aqueous electrolyte solution contains a compound represented by the general formula (I), and further from the group consisting of monofluorophosphate and difluorophosphate. A non-aqueous electrolyte containing at least one selected compound .

(In General Formula (I), R ₁ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, and R _{2 to} R ₆ are each independently a hydrogen atom, a fluorine atom, or a fluorine atom. Represents an alkyl group having 1 to 12 carbon atoms which may be substituted with an atom, provided that at least one of R _{2 to} R ₆ represents an alkyl group having 2 or more carbon atoms which may be substituted with a fluorine atom. Represents an integer of 1 (except that at least one of R _{2 to} R ₆ is a cyclohexyl group) .) (2) In the general formula (I), R ₁ is a methyl group, an ethyl group, or a vinyl group. Represents a group selected from the group consisting of a phenyl group and a trifluoromethyl group, and R _{2 to} R ₆ each independently represents an alkyl group having 2 to 6 carbon atoms which may be substituted with a hydrogen atom or a fluorine atom. The above (1) characterized in that Nonaqueous electrolytic solution according to.
(3) In the general formula (I), at least one of R _{2 to} R ₆ represents an alkyl group having 4 or more carbon atoms which may be substituted with a fluorine atom, (1) or (2 ) Non-aqueous electrolyte.
(4) The ratio of the compound represented by the general formula (I) in the non-aqueous electrolyte is 0.001 to 10% by mass, and the non-aqueous system according to (1) to (3) above Electrolytic solution.
(5) In addition, a carbon - the (1, characterized by containing carbon unsaturated cyclic carbonate compounds having a bond, and at least one compound selected from the cyclic carbonate compound or Ranaru group having a fluorine atom ) To the non-aqueous electrolyte solution according to any one of (4).
(6) A non-aqueous electrolyte battery including 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 any one of (1) to (5) above. A non-aqueous electrolyte battery characterized by being a non-aqueous electrolyte.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery having a high capacity and excellent high-temperature storage characteristics, in particular, high-temperature continuous charging characteristics, while improving safety during overcharging. Miniaturization and high performance can be achieved.

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.
<Non-aqueous electrolyte>
The non-aqueous electrolyte solution of the present invention, like a general non-aqueous electrolyte solution, usually has an electrolyte and a non-aqueous solvent that dissolves it as a main component, and is further represented by the general formula (I). Contains compounds.

(In General Formula (I), R ₁ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, and R _{2 to} R ₆ are each independently a hydrogen atom, a fluorine atom, or a fluorine atom. Represents an optionally substituted alkyl group having 1 to 12 carbon atoms, and n represents an integer of 0 or 1. However, when n is 0, at least one of R _{2 to} R ₆ is a fluorine atom. Represents an optionally substituted alkyl group having 2 or more carbon atoms, and when n is 1, at least one of R _{2 to} R ₆ represents an alkyl group having 5 or more carbon atoms which may be substituted with a fluorine atom. .)

In the formula (I), the hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a fluorine atom represented by R _1, an alkyl group having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms Group, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, and the like.
Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, pentyl group, A cyclopentyl group, a cyclohexyl group, etc. are mentioned, Preferably it is a C1-C6, Especially preferably, it is a 1-4 chain or cyclic alkyl group, However, It is preferable that it is a chain alkyl group.

As a C2-C12 alkenyl group, a vinyl group, a propenyl group, etc. are mentioned, Preferably it is 2-8, Most preferably, the thing of 2-4 is mentioned.
Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a cyclohexylphenyl group, and a t-butylphenyl group, and among them, a phenyl group, a cyclohexylphenyl group, and a t-butylphenyl group are preferable. .

Examples of the aralkyl group having 7 to 12 carbon atoms include a benzyl group and a phenethyl group, and among them, a benzyl group is preferable.
The alkyl group, alkenyl group, aryl group and aralkyl group may be substituted with a fluorine atom. Examples of the fluorine-substituted group include a trifluoromethyl group, a trifluoroethyl group and a pentafluoroethyl group. Fluorinated alkyl groups, 2-fluorovinyl groups, fluorinated alkenyl groups such as 3-fluoro-2-propenyl group, 2-fluorophenyl groups, 3-fluorophenyl groups, fluorinated aryl groups such as 4-fluorophenyl groups, Examples thereof include fluorinated aralkyl groups such as 2-fluorobenzyl group, 3-fluorobenzyl group and 4-fluorobenzyl group.

R ₁ is more preferably a group selected from the group consisting of a methyl group, an ethyl group, a vinyl group, a phenyl group, and a trifluoromethyl group. Furthermore, a group selected from the group consisting of a methyl group, an ethyl group and a trifluoromethyl group is preferable.
In general formula (I), examples of the alkyl group having 1 to 12 carbon atoms which may be substituted with a fluorine atom represented by R _{2 to} R ₆ include a methyl group, an ethyl group, an n-propyl group, and i-propyl. Group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, t-amyl group, n-hexyl group, 1,1-dimethylbutyl group, cyclobutyl group, cyclopentyl group , A cyclohexyl group, a 1-methylcyclohexyl group, a 1-ethylcyclohexyl group, and the like, and preferably a linear or cyclic alkyl group having 1 to 6 carbon atoms. Examples of the fluorine-substituted group include a trifluoromethyl group, a trifluoroethyl group, and a pentafluoroethyl group.

In general formula (I), R _{2 to} R ₆ are each independently more preferably an alkyl group having 2 to 6 carbon atoms which may be substituted with a hydrogen atom or a fluorine atom.
In general formula (I), when n is 0, at least one of R _{2 to} R ₆ represents an alkyl group having 2 or more carbon atoms, and when n is 1, at least one of R _{2 to} R ₆ is carbon. An alkyl group having a number of 5 or more is represented. From the viewpoint of improving safety during overcharge and improving battery characteristics, at least one of R _{2 to} R ₆ is preferably an alkyl group having 3 or more carbon atoms, more preferably an alkyl group having 4 or more carbon atoms, More preferably, it is an alkyl group having 5 or more carbon atoms. The alkyl group may be substituted with a fluorine atom.

Examples of the alkyl group having 4 or more carbon atoms include n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, t-amyl group, n-hexyl group, 1,1-dimethyl group. Examples include a butyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 1-methylcyclohexyl group, and a 1-ethylcyclohexyl group.
The alkyl group having 4 or more carbon atoms is preferably a secondary alkyl group or a tertiary alkyl group, and among them, sec-butyl group, t-butyl group, t-amyl group, 1,1-dimethylbutyl group, cyclopentyl. Group, cyclohexyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group are more preferable, t-butyl group, t-amyl group, 1,1-dimethylbutyl group, cyclopentyl group, cyclohexyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group is more preferable, and t-amyl group, 1,1-dimethylbutyl group, cyclopentyl group, cyclohexyl group, 1-methylcyclohexyl group, which is a secondary alkyl group or tertiary alkyl group having 5 or more carbon atoms, A 1-ethylcyclohexyl group is particularly preferred.

Specific examples of the compound represented by the general formula (I) include the following compounds.
(Compound with n = 1)
Methanesulfonic acid (2-n-pentylphenyl), methanesulfonic acid (3-n-pentylphenyl), methanesulfonic acid (4-n-pentylphenyl), methanesulfonic acid (2,4-di-n-pentylphenyl) ), Methanesulfonic acid (3,5-di-n-pentylphenyl), methanesulfonic acid (2-t-amylphenyl), methanesulfonic acid (3-t-amylphenyl), methanesulfonic acid (4-t- Amylphenyl), methanesulfonic acid (2,4-di-t-amylphenyl), methanesulfonic acid (3,5-di-t-amylphenyl), methanesulfonic acid (2-cyclopentylphenyl), methanesulfonic acid ( 3-cyclopentylphenyl), methanesulfonic acid (4-cyclopentylphenyl), methanesulfonic acid (2-cyclohexylphenol) ), Methanesulfonic acid (3-cyclohexylphenyl), methanesulfonic acid (4-cyclohexylphenyl), ethanesulfonic acid (2-n-pentylphenyl), ethanesulfonic acid (3-n-pentylphenyl), ethanesulfonic acid (4-n-pentylphenyl), ethanesulfonic acid (2,4-di-n-pentylphenyl), ethanesulfonic acid (3,5-di-n-pentylphenyl), ethanesulfonic acid (2-t-amyl) Phenyl), ethanesulfonic acid (3-t-amylphenyl), ethanesulfonic acid (4-t-amylphenyl), ethanesulfonic acid (2-cyclopentylphenyl), ethanesulfonic acid (3-cyclopentylphenyl), ethanesulfonic acid (4-cyclopentylphenyl), ethanesulfonic acid (2-cyclohexylphenol) ), Ethanesulfonic acid (3-cyclohexylphenyl), ethanesulfonic acid (4-cyclohexylphenyl), propanesulfonic acid (2-n-pentylphenyl), propanesulfonic acid (3-n-pentylphenyl), propanesulfonic acid (4-n-pentylphenyl), propanesulfonic acid (2,4-di-n-pentylphenyl), propanesulfonic acid (3,5-di-n-pentylphenyl), propanesulfonic acid (2-t-amyl) Phenyl), propanesulfonic acid (3-t-amylphenyl), propanesulfonic acid (4-t-amylphenyl), propanesulfonic acid (2-cyclopentylphenyl), propanesulfonic acid (3-cyclopentylphenyl), propanesulfonic acid (4-cyclopentylphenyl), propanesulfonic acid ( Compounds in which R ₁ is an alkyl group having 1 to 12 carbon atoms, such as 2-cyclohexylphenyl), propanesulfonic acid (3-cyclohexylphenyl), and propanesulfonic acid (4-cyclohexylphenyl);
Vinylsulfonic acid (2-n-pentylphenyl), vinylsulfonic acid (3-pentylphenyl), vinylsulfonic acid (4-n-pentylphenyl), vinylsulfonic acid (2,4-di-n-pentylphenyl), Vinylsulfonic acid (3,5-di-n-pentylphenyl), vinylsulfonic acid (2-t-amylphenyl), vinylsulfonic acid (3-t-amylphenyl), vinylsulfonic acid (4-t-amylphenyl) ), Vinyl sulfonic acid (2-cyclopentylphenyl), vinyl sulfonic acid (3-cyclopentylphenyl), vinyl sulfonic acid (4-cyclopentylphenyl), vinyl sulfonic acid (2-cyclohexylphenyl), vinyl sulfonic acid (3-cyclohexylphenyl) ), Vinyl sulfonic acid (4-cyclohexylphenyl), ants Sulfonic acid (2-n-pentylphenyl), allylsulfonic acid (3-n-pentylphenyl), allylsulfonic acid (4-n-pentylphenyl), allylsulfonic acid (2,4-di-n-pentylphenyl) Allylsulfonic acid (3,5-di-n-pentylphenyl), allylsulfonic acid (2-t-amylphenyl), allylsulfonic acid (3-t-amylphenyl), allylsulfonic acid (4-t-amyl) Phenyl), allylsulfonic acid (2-cyclopentylphenyl), allylsulfonic acid (3-cyclopentylphenyl), allylsulfonic acid (4-cyclopentylphenyl), allylsulfonic acid (2-cyclohexylphenyl), allylsulfonic acid (3-cyclohexyl) phenyl), R and allyl sulfonic acid (4-cyclohexyl-phenyl) Compounds There is an alkenyl group having 2 to 12 carbon atoms;
Benzenesulfonic acid (2-n-pentylphenyl), benzenesulfonic acid (3-n-pentylphenyl), benzenesulfonic acid (4-n-pentylphenyl), benzenesulfonic acid (2,4-di-n-pentylphenyl) ), Benzenesulfonic acid (3,5-di-n-pentylphenyl), benzenesulfonic acid (2-t-amylphenyl), benzenesulfonic acid (3-t-amylphenyl), benzenesulfonic acid (4-t- Amylphenyl), benzenesulfonic acid (2-cyclopentylphenyl), benzenesulfonic acid (3-cyclopentylphenyl), benzenesulfonic acid (4-cyclopentylphenyl), benzenesulfonic acid (2-cyclohexylphenyl), benzenesulfonic acid (3- (Cyclohexylphenyl), benzenesulfonic acid (4 Cyclohexylphenyl), p-toluenesulfonic acid (2-n-pentylphenyl), p-toluenesulfonic acid (3-n-pentylphenyl), p-toluenesulfonic acid (4-n-pentylphenyl), p-toluenesulfone Acid (2,4-di-n-pentylphenyl), p-toluenesulfonic acid (3,5-di-n-pentylphenyl), p-toluenesulfonic acid (2-t-amylphenyl), p-toluenesulfone Acid (3-t-amylphenyl), p-toluenesulfonic acid (4-t-amylphenyl), p-toluenesulfonic acid (2-cyclopentylphenyl), p-toluenesulfonic acid (3-cyclopentylphenyl), p- Toluenesulfonic acid (4-cyclopentylphenyl), p-toluenesulfonic acid (2-cyclohexylphenyl) , P- toluenesulfonic acid (3-phenyl), Compound _{R 1,} such as p- toluenesulfonic acid (4-cyclohexyl-phenyl) is an aryl group having 6 to 12 carbon atoms;
Benzylsulfonic acid (2-n-pentylphenyl), benzylsulfonic acid (3-n-pentylphenyl), benzylsulfonic acid (4-n-pentylphenyl), benzylsulfonic acid (2,4-di-n-pentylphenyl) ), Benzylsulfonic acid (3,5-di-n-pentylphenyl), benzylsulfonic acid (2-t-amylphenyl), benzylsulfonic acid (3-t-amylphenyl), benzylsulfonic acid (4-t- Amylphenyl), benzylsulfonic acid (2-cyclopentylphenyl), benzylsulfonic acid (3-cyclopentylphenyl), benzylsulfonic acid (4-cyclopentylphenyl), benzylsulfonic acid (2-cyclohexylphenyl), benzylsulfonic acid (3- (Cyclohexylphenyl), benzylsulfonic acid (4 Compound _{R 1} cyclohexyl phenyl) or the like is an aralkyl group having 7 to 12 carbon atoms;
Trifluoromethanesulfonic acid (2-n-pentylphenyl), trifluoromethanesulfonic acid (3-n-pentylphenyl), trifluoromethanesulfonic acid (4-n-pentylphenyl), trifluoromethanesulfonic acid (2,4-di-) n-pentylphenyl), trifluoromethanesulfonic acid (3,5-di-n-pentylphenyl), trifluoromethanesulfonic acid (2-t-amylphenyl), trifluoromethanesulfonic acid (3-t-amylphenyl), trifluoro L-methanesulfonic acid (4-t-amylphenyl), trifluoromethanesulfonic acid (2-cyclopentylphenyl), trifluoromethanesulfonic acid (3-cyclopentylphenyl), trifluoromethanesulfonic acid (4-cyclopentylphenyl), trifluoro Tansulfonic acid (2-cyclohexylphenyl), trifluoromethanesulfonic acid (3-cyclohexylphenyl), trifluoromethanesulfonic acid (4-cyclohexylphenyl), trifluoroethanesulfonic acid (2-n-pentylphenyl), trifluoroethanesulfone Acid (3-n-pentylphenyl), trifluoroethanesulfonic acid (4-n-pentylphenyl), trifluoroethanesulfonic acid (2,4-di-n-pentylphenyl), trifluoroethanesulfonic acid (3,3 5-di-n-pentylphenyl), trifluoroethanesulfonic acid (2-t-amylphenyl), trifluoroethanesulfonic acid (3-t-amylphenyl), trifluoroethanesulfonic acid (4-t-amylphenyl) ), Trifluoroethanesulfo Acid (2-cyclopentylphenyl), trifluoroethanesulfonic acid (3-cyclopentylphenyl), trifluoroethanesulfonic acid (4-cyclopentylphenyl), trifluoroethanesulfonic acid (2-cyclohexylphenyl), trifluoroethanesulfonic acid ( Compounds in which R ₁ is a fluorine-substituted alkyl group having 1 to 12 carbon atoms, such as 3-cyclohexylphenyl) and trifluoroethanesulfonic acid (4-cyclohexylphenyl).

(Compound with n = 0)
Methyl (2-ethylphenyl) sulfone, methyl (3-ethylphenyl) sulfone, methyl (4-ethylphenyl) sulfone, methyl (2-n-propylphenyl) sulfone, methyl (3-n-propylphenyl) sulfone, methyl (4-n-propylphenyl) sulfone, methyl (2-i-propylphenyl) sulfone, methyl (3-i-propylphenyl) sulfone, methyl (4-i-propylphenyl) sulfone, methyl (2-n-butyl) Phenyl) sulfone, methyl (3-n-butylphenyl) sulfone, methyl (4-n-butylphenyl) sulfone, methyl (2-i-butylphenyl) sulfone, methyl (3-i-butylphenyl) sulfone, methyl ( 4-i-butylphenyl) sulfone, methyl (2-sec-butylphenyl) Ruphone, methyl (3-sec-butylphenyl) sulfone, methyl (4-sec-butylphenyl) sulfone, methyl (2-t-butylphenyl) sulfone, methyl (3-t-butylphenyl) sulfone, methyl (4- t-butylphenyl) sulfone, methyl (2,4-di-t-butylphenyl) sulfone, methyl (3,5-di-t-butylphenyl) sulfone, methyl (2-t-amylphenyl) sulfone, methyl ( 3-t-amylphenyl) sulfone, methyl (4-t-amylphenyl) sulfone, methyl (2,4-di-t-amylphenyl) sulfone, methyl (3,5-di-t-amylphenyl) sulfone, Methyl (2-cyclopentylphenyl) sulfone, methyl (3-cyclopentylphenyl) sulfone, methyl (4-cyclopentyl) Tilphenyl) sulfone, methyl (2-cyclohexylphenyl) sulfone, methyl (3-cyclohexylphenyl) sulfone, methyl (4-cyclohexylphenyl) sulfone, ethyl (2-ethylphenyl) sulfone, ethyl (3-ethylphenyl) sulfone, ethyl (4-ethylphenyl) sulfone, ethyl (2-n-propylphenyl) sulfone, ethyl (3-n-propylphenyl) sulfone, ethyl (4-n-propylphenyl) sulfone, ethyl (2-i-propylphenyl) Sulfone, ethyl (3-i-propylphenyl) sulfone, ethyl (4-i-propylphenyl) sulfone, ethyl (2-n-butylphenyl) sulfone, ethyl (3-n-butylphenyl) sulfone, ethyl (4- n-butylphenyl) sulfone, Ethyl (2-i-butylphenyl) sulfone, ethyl (3-i-butylphenyl) sulfone, ethyl (4-i-butylphenyl) sulfone, ethyl (2-sec-butylphenyl) sulfone, ethyl (3-sec- Butylphenyl) sulfone, ethyl (4-sec-butylphenyl) sulfone, ethyl (2-tert-butylphenyl) sulfone, ethyl (3-tert-butylphenyl) sulfone, ethyl (4-tert-butylphenyl) sulfone, ethyl (2-t-amylphenyl) sulfone, ethyl (3-t-amylphenyl) sulfone, ethyl (4-t-amylphenyl) sulfone, ethyl (2-cyclopentylphenyl) sulfone, ethyl (3-cyclopentylphenyl) sulfone, Ethyl (4-cyclopentylphenyl) sulfone, ethyl (2- Black hexyl) sulfone, ethyl (3-phenyl) sulfone, ethyl (4-cyclohexyl-phenyl) _{R 1} of the sulfone
In which is an alkyl group having 1 to 12 carbon atoms;
Vinyl (2-ethylphenyl) sulfone, vinyl (3-ethylphenyl) sulfone, vinyl (4-ethylphenyl) sulfone, vinyl (2-n-propylphenyl) sulfone, vinyl (3-n-propylphenyl) sulfone, vinyl (4-n-propylphenyl) sulfone, vinyl (2-i-propylphenyl) sulfone, vinyl (3-i-propylphenyl) sulfone, vinyl (4-i-propylphenyl) sulfone, vinyl (2-n-butyl) Phenyl) sulfone, vinyl (3-n-butylphenyl) sulfone, vinyl (4-n-butylphenyl) sulfone, vinyl (2-i-butylphenyl) sulfone, vinyl (3-i-butylphenyl) sulfone, vinyl ( 4-i-Butylphenyl) sulfone, vinyl (2-sec-butylphenyl) Ruhon, vinyl (3-sec-butylphenyl) sulfone, vinyl (4-sec-butylphenyl) sulfone, vinyl (2-t-butylphenyl) sulfone, vinyl (3-t-butylphenyl) sulfone, vinyl (4- t-butylphenyl) sulfone, vinyl (2-t-amylphenyl) sulfone, vinyl (3-t-amylphenyl) sulfone, vinyl (4-t-amylphenyl) sulfone, vinyl (2-cyclopentylphenyl) sulfone, vinyl (3-cyclopentylphenyl) sulfone, vinyl (4-cyclopentylphenyl) sulfone, vinyl (2-cyclohexylphenyl) sulfone, vinyl (3-cyclohexylphenyl) sulfone, vinyl (4-cyclohexylphenyl) sulfone, allyl (2-ethylphenyl) ) Sulfone Allyl (3-ethylphenyl) sulfone, allyl (4-ethylphenyl) sulfone, allyl (2-n-propylphenyl) sulfone, allyl (3-n-propylphenyl) sulfone, allyl (4-n-propylphenyl) sulfone Allyl (2-i-propylphenyl) sulfone, allyl (3-i-propylphenyl) sulfone, allyl (4-i-propylphenyl) sulfone, allyl (2-n-butylphenyl) sulfone, allyl (3-n -Butylphenyl) sulfone, allyl (4-n-butylphenyl) sulfone, allyl (2-i-butylphenyl) sulfone, allyl (3-i-butylphenyl) sulfone, allyl (4-i-butylphenyl) sulfone, Allyl (2-sec-butylphenyl) sulfone, allyl (3-sec-butylphenyl) Phenyl) sulfone, allyl (4-sec-butylphenyl) sulfone, allyl (2-t-butylphenyl) sulfone, allyl (3-t-butylphenyl) sulfone, allyl (4-t-butylphenyl) sulfone, allyl ( 2-t-amylphenyl) sulfone, allyl (3-t-amylphenyl) sulfone, allyl (4-t-amylphenyl) sulfone, allyl (2-cyclopentylphenyl) sulfone, allyl (3-cyclopentylphenyl) sulfone, allyl Compounds in which R ₁ is an alkenyl group having 2 to 12 carbon atoms, such as (4-cyclopentylphenyl) sulfone, allyl (2-cyclohexylphenyl) sulfone, allyl (3-cyclohexylphenyl) sulfone, allyl (4-cyclohexylphenyl) sulfone ;
Phenyl (2-ethylphenyl) sulfone, phenyl (3-ethylphenyl) sulfone, phenyl (4-ethylphenyl) sulfone, phenyl (2-n-propylphenyl) sulfone, phenyl (3-n-propylphenyl) sulfone, phenyl (4-n-propylphenyl) sulfone, phenyl (2-i-propylphenyl) sulfone, phenyl (3-i-propylphenyl) sulfone, phenyl (4-i-propylphenyl) sulfone, phenyl (2-n-butyl) Phenyl) sulfone, phenyl (3-n-butylphenyl) sulfone, phenyl (4-n-butylphenyl) sulfone, phenyl (2-i-butylphenyl) sulfone, phenyl (3-i-butylphenyl) sulfone, phenyl ( 4-i-butylphenyl) sulfone, phenyl (2-sec-butylphenyl) sulfone, phenyl (3-sec-butylphenyl) sulfone, phenyl (4-sec-butylphenyl) sulfone, phenyl (2-t-butylphenyl) sulfone, phenyl (3-t-butyl) Phenyl) sulfone, phenyl (4-t-butylphenyl) sulfone, phenyl (2-t-amylphenyl) sulfone, phenyl (3-t-amylphenyl) sulfone, phenyl (4-t-amylphenyl) sulfone, phenyl ( 2-cyclopentylphenyl) sulfone, phenyl (3-cyclopentylphenyl) sulfone, phenyl (4-cyclopentylphenyl) sulfone, phenyl (2-cyclohexylphenyl) sulfone, phenyl (3-cyclohexylphenyl) sulfone, phenyl (4-cyclohexyl) Ruphenyl) sulfone, bis (2-t-butylphenyl) sulfone, bis (3-t-butylphenyl) sulfone, bis (4-t-butylphenyl) sulfone, bis (2-t-amylphenyl) sulfone, bis ( 3-t-amylphenyl) sulfone, bis (4-t-amylphenyl) sulfone, bis (2-cyclopentylphenyl) sulfone, bis (3-cyclopentylphenyl) sulfone, bis (4-cyclopentylphenyl) sulfone, bis (2 A compound in which R ₁ is an aryl group having 6 to 12 carbon atoms, such as -cyclohexylphenyl) sulfone, bis (3-cyclohexylphenyl) sulfone, and bis (4-cyclohexylphenyl) sulfone;
Benzyl (2-ethylphenyl) sulfone, benzyl (3-ethylphenyl) sulfone, benzyl (4-ethylphenyl) sulfone, benzyl (2-n-propylphenyl) sulfone, benzyl (3-n-propylphenyl) sulfone, benzyl (4-n-propylphenyl) sulfone, benzyl (2-i-propylphenyl) sulfone, benzyl (3-i-propylphenyl) sulfone, benzyl (4-i-propylphenyl) sulfone, benzyl (2-n-butyl) Phenyl) sulfone, benzyl (3-n-butylphenyl) sulfone, benzyl (4-n-butylphenyl) sulfone, benzyl (2-i-butylphenyl) sulfone, benzyl (3-i-butylphenyl) sulfone, benzyl ( 4-i-butylphenyl) sulfone, benzine (2-sec-butylphenyl) sulfone, benzyl (3-sec-butylphenyl) sulfone, benzyl (4-sec-butylphenyl) sulfone, benzyl (2-t-butylphenyl) sulfone, benzyl (3-t-butyl) Phenyl) sulfone, benzyl (4-t-butylphenyl) sulfone, benzyl (2-t-amylphenyl) sulfone, benzyl (3-t-amylphenyl) sulfone, benzyl (4-t-amylphenyl) sulfone, benzyl ( 2-cyclopentylphenyl) sulfone, benzyl (3-cyclopentylphenyl) sulfone, benzyl (4-cyclopentylphenyl) sulfone, benzyl (2-cyclohexylphenyl) sulfone, benzyl (3-cyclohexylphenyl) sulfone, benzyl (4-cyclohexyl) Butylphenyl) Compound _{R 1} is an aralkyl group having 7 to 12 carbon atoms sulfone;
Trifluoromethyl (2-ethylphenyl) sulfone, trifluoromethyl (3-ethylphenyl) sulfone, trifluoromethyl (4-ethylphenyl) sulfone, trifluoromethyl (2-n-propylphenyl) sulfone, trifluoromethyl ( 3-n-propylphenyl) sulfone, trifluoromethyl (4-n-propylphenyl) sulfone, trifluoromethyl (2-i-propylphenyl) sulfone, trifluoromethyl (3-i-propylphenyl) sulfone, trifluoro Methyl (4-i-propylphenyl) sulfone, trifluoromethyl (2-n-butylphenyl) sulfone, trifluoromethyl (3-n-butylphenyl) sulfone, trifluoromethyl (4-n-butylphenyl) sulfone, Trifluoromethyl 2-i-butylphenyl) sulfone, trifluoromethyl (3-i-butylphenyl) sulfone, trifluoromethyl (4-i-butylphenyl) sulfone, trifluoromethyl (2-sec-butylphenyl) sulfone, trifluoro Methyl (3-sec-butylphenyl) sulfone, trifluoromethyl (4-sec-butylphenyl) sulfone, trifluoromethyl (2-t-butylphenyl) sulfone, trifluoromethyl (3-t-butylphenyl) sulfone, Trifluoromethyl (4-t-butylphenyl) sulfone, trifluoromethyl (2-t-amylphenyl) sulfone, trifluoromethyl (3-t-amylphenyl) sulfone, trifluoromethyl (4-t-amylphenyl) Sulfone, trifluoromethyl (2- Clopentylphenyl) sulfone, trifluoromethyl (3-cyclopentylphenyl) sulfone, trifluoromethyl (4-cyclopentylphenyl) sulfone, trifluoromethyl (2-cyclohexylphenyl) sulfone, trifluoromethyl (3-cyclohexylphenyl) sulfone, Trifluoromethyl (4-cyclohexylphenyl) sulfone, trifluoroethyl (2-ethylphenyl) sulfone, trifluoroethyl (3-ethylphenyl) sulfone, trifluoroethyl (4-ethylphenyl) sulfone, trifluoroethyl (2- n-propylphenyl) sulfone, trifluoroethyl (3-n-propylphenyl) sulfone, trifluoroethyl (4-n-propylphenyl) sulfone, trifluoroethyl (2-i -Propylphenyl) sulfone, trifluoroethyl (3-i-propylphenyl) sulfone, trifluoroethyl (4-i-propylphenyl) sulfone, trifluoroethyl (2-n-butylphenyl) sulfone, trifluoroethyl (3 -N-butylphenyl) sulfone, trifluoroethyl (4-n-butylphenyl) sulfone, trifluoroethyl (2-i-butylphenyl) sulfone, trifluoroethyl (3-i-butylphenyl) sulfone, trifluoroethyl (4-i-butylphenyl) sulfone, trifluoroethyl (2-sec-butylphenyl) sulfone, trifluoroethyl (3-sec-butylphenyl) sulfone, trifluoroethyl (4-sec-butylphenyl) sulfone, tri Fluoroethyl (2-t Butylphenyl) sulfone, trifluoroethyl (3-tert-butylphenyl) sulfone, trifluoroethyl (4-tert-butylphenyl) sulfone, trifluoroethyl (2-tert-amylphenyl) sulfone, trifluoroethyl (3- t-amylphenyl) sulfone, trifluoroethyl (4-t-amylphenyl) sulfone, trifluoroethyl (2-cyclopentylphenyl) sulfone, trifluoroethyl (3-cyclopentylphenyl) sulfone, trifluoroethyl (4-cyclopentylphenyl) ) sulfone, trifluoroethyl (2-cyclohexyl) sulfone, trifluoroethyl (3-cyclohexyl) sulfone, trifluoroethyl (4-cyclohexyl-phenyl) R ₁ is of fluorine-substituted sulfone And are an alkyl group having 1 to 12 carbon atoms compound.

Among the above compounds, at least one of R _{2 to} R ₆ in the general formula (1) is a secondary alkyl group having 4 or more carbon atoms or 3 in terms of improving safety during overcharge and improving high-temperature continuous charge characteristics. A compound that is a secondary alkyl group is preferable, and a compound in which at least one of R _{2 to} R ₆ in the general formula (I) is any one of a t-butyl group, a t-amyl group, a cyclopentyl group, and a cyclohexyl group is more preferable. A compound in which n in the formula (I) is 1, and at least one of R _{2 to} R ₆ is any one of a t-amyl group, a cyclopentyl group, and a cyclohexyl group is more preferable, and n in the general formula (I) is 1, A compound in which R ₄ is any one of a t-amyl group, a cyclopentyl group, and a cyclohexyl group is particularly preferable.

More particularly, a compound in which n in general formula (I) is 1, R ₁ is a methyl group, R ₂ , R ₃ , R ₅ and R ₆ are hydrogen atoms, and R ₄ is a cyclohexyl group or a t-amyl group preferable. Among them, a compound in which n in the general formula (I) is 1, R ₁ is a methyl group, R ₂ , R ₃ , R ₅ and R ₆ are hydrogen atoms, and R ₄ is a cyclohexyl group is most preferable.
The compounds represented by formula (I) may be used alone or in combination of two or more.
The proportion of the compound represented by the general formula (I) in the non-aqueous electrolyte is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, particularly Preferably it is 0.1 mass% or more. If the concentration is lower than this, the effects of the present invention may not be easily exhibited. On the other hand, if the concentration is too high, the capacity of the battery may decrease, so it is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Most preferably, it is 1.5 mass% or less.

The reason why the non-aqueous electrolyte solution according to the present invention is excellent in safety during overcharge and excellent in high-temperature continuous charge characteristics is not clear, and the present invention is not limited to the following operation principle. It is guessed as follows.
The compound represented by the general formula (I) has a specific sulfur-containing functional group in the molecule and, when n is 0, a phenyl group substituted with an alkyl group having 2 or more carbon atoms, and n is 1. In some cases, it has a phenyl group substituted with an alkyl group having 5 or more carbon atoms.

  In general, the electron donating property of an alkyl group increases as the carbon number of the alkyl group increases. Further, the secondary alkyl group and the tertiary alkyl group have higher electron donating properties than the primary alkyl group. Therefore, compared to a compound having a phenyl group not substituted with an alkyl group, a compound having a phenyl group substituted with an alkyl group having 2 or more carbon atoms has a lower oxidation potential and reacts at an earlier stage during overcharge. Safety during overcharge can be improved. Normally, a compound with a low oxidation potential reacts at a site where the electrode activity is high even during high-temperature continuous charging, and deteriorates battery characteristics after high-temperature continuous charging, but certain sulfur-containing functional groups are present on the surface of the positive electrode. By adsorbing, it is considered that side reaction with a highly active positive electrode can be suppressed, and deterioration of battery characteristics after high-temperature continuous charging can be suppressed while enhancing safety during overcharging.

  In particular, when it has a phenyl group substituted with an alkyl group having 5 or more carbon atoms, side reactions with a highly active positive electrode can be further suppressed due to steric hindrance of the alkyl group, and safety during overcharge is increased. However, it is thought that the effect which suppresses the fall of the battery characteristic after high temperature continuous charge is high.

(Electrolytes)
There is no restriction | limiting in the electrolyte used for the non-aqueous electrolyte solution of this invention, A well-known thing can be used arbitrarily if it is used as an electrolyte for the target non-aqueous electrolyte secondary battery.
When the nonaqueous electrolytic solution of the present invention is used for a lithium secondary battery, a lithium salt is usually used as an electrolyte.
Specific examples of the electrolyte include inorganic lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiFSO ₃ ; LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-tetrafluoroethane disulfonylimide, lithium cyclic 1,3-hexafluoropropane disulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , 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 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 , etc. Fluorine-containing organic lithium salt; lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluorooxalatophosphate, etc. Can be mentioned.

Among these, LiPF ₆ , LiBF ₄ , LiFSO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-tetrafluoroethanedisulfonylimide , Lithium cyclic 1,3-hexafluoropropane disulfonylimide, lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluorooxalatophosphate In particular, LiPF ₆ and LiBF ₄ are preferable.

Moreover, these lithium salts may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. In particular, the combined use of specific inorganic lithium salts and the combined use of inorganic lithium salts with fluorine-containing organic lithium salts and carboxylic acid complex lithium salts suppresses gas generation during high-temperature storage or suppresses deterioration after high-temperature storage. Therefore, it is preferable.
In particular, the combination and the LiPF ₆ and LiBF _4, and an inorganic lithium salt such as _{LiPF 6, LiBF 4, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, lithium Fluorine-containing organic lithium salts such as cyclic 1,2-tetrafluoroethanedisulfonylimide and lithium cyclic 1,3-hexafluoropropanedisulfonylimide, lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris ( It is preferable to use in combination with a dicarboxylic acid complex lithium salt such as oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluorooxalatophosphate.

When used in combination LiPF ₆ and LiBF ₄ are the content of LiBF ₄ to the total of LiPF ₆ and LiBF ₄ is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably It is 0.1% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 3% by mass or less.
If it is less than this range, the desired effect may not be obtained, and if it exceeds this range, battery characteristics such as high load discharge characteristics may deteriorate.

Meanwhile, inorganic lithium salts such as LiPF ₆ and LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-tetrafluoroethanedisulfonyl Fluorine-containing organic lithium salts such as imides and lithium cyclic 1,3-hexafluoropropanedisulfonylimide, lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) When a dicarboxylic acid complex lithium salt such as phosphate or lithium tetrafluorooxalate phosphate is used in combination, the content of the inorganic lithium salt in the total of both is preferably 70% by mass or more, more preferably 80% by mass or more, Preferably 8 And% by mass or more, preferably 99 wt% or less, more preferably 95 wt% or less.

  The concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited in order to exhibit the effects of the present invention, but is preferably 0.5 mol / liter or more, more preferably 0.8 mol / liter or more. More preferably, it is 1.0 mol / liter or more. Further, it is preferably 3 mol / liter or less, more preferably 2 mol / liter or less, still more preferably 1.8 mol / liter or less, and particularly preferably 1.6 mol / liter or less. If the concentration is too low, the electrical conductivity of the electrolyte solution may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to an increase in viscosity, and the battery performance may decrease. .

(Non-aqueous solvent)
The non-aqueous solvent can also be appropriately selected from conventionally known solvents for non-aqueous electrolyte solutions. For example, cyclic carbonates, chain carbonates, cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic ethers, chain ethers, sulfur-containing organic solvents, phosphorus-containing organic solvents, aromatic fluorine-containing solvents, etc. Can be mentioned.

Examples of the cyclic carbonates 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 preferable from the viewpoint of improving battery characteristics. In particular, ethylene carbonate is preferred. Further, a part of hydrogen of these compounds may be substituted with fluorine.
Examples of cyclic carbonates substituted with fluorine include fluoroethylene carbonate, 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, tetrafluoroethylene carbonate, 1-fluoro- Such as 2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, etc. Examples include alkylene carbonates having an alkylene group substituted with fluorine having 2 to 4 carbon atoms. Among these, fluoroethylene carbonate, 1,2-difluoroethylene carbonate, trifluoromethyl Ethylene carbonate is preferred.

  As the chain carbonates, dialkyl carbonates are preferable, and the number of carbon atoms of the alkyl group constituting each is preferably 1 to 5, particularly preferably 1 to 4. Specifically, for example, symmetric chain alkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-n-propyl carbonate; asymmetric chain alkyls such as ethyl methyl carbonate, methyl-n-propyl carbonate, and ethyl-n-propyl carbonate Examples include carbonates, and among them, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable from the viewpoint of improving battery characteristics. Further, a part of hydrogen of the alkyl group may be substituted with fluorine. Examples of chain carbonates substituted with fluorine include bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis (trifluoromethyl) carbonate, bis (2-fluoroethyl) carbonate, and bis (2,2-difluoroethyl). ) Carbonate, bis (2,2,2-trifluoroethyl) carbonate, 2-fluoroethyl methyl carbonate, 2,2-difluoroethyl methyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, and the like.

Examples of the cyclic carboxylic acid esters include γ-butyrolactone, γ-valerolactone, and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine.
Examples of chain carboxylates include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, propion Examples include isopropyl acid, methyl butyrate, ethyl butyrate, propyl butyrate, methyl valerate, ethyl valerate, etc., and compounds in which part of hydrogen of these compounds such as propyl trifluoroacetate and butyl trifluoroacetate is substituted with fluorine. Methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and methyl valerate are more preferred.

Examples of the cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine.
Examples of chain ethers include dimethoxyethane, diethoxyethane, and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine. Bis trifluoroethoxyethane, ethoxytrifluoroethoxyethane, methoxytrifluoroethoxyethane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane, 1,1,1,2,2,3,4,5 , 5,5-decafluoro-3-ethoxy-4-trifluoromethyl-pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-propoxy-4-tri Fluoromethyl-pentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl-2,2,3,3- Tiger fluoropropyl ether.

Examples of the sulfur-containing organic solvent include sulfolane, 2-methylsulfolane, 3-methylsulfolane, diethylsulfone, ethylmethylsulfone, methylpropylsulfone, and the like, and compounds in which part of hydrogen of these compounds is substituted with fluorine.
Examples of the phosphorus-containing organic solvent include trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, etc., and compounds in which part of hydrogen of these compounds is substituted with fluorine Is mentioned.

Examples of the aromatic fluorine-containing solvent include fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride and the like.
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, it is preferable to use a high dielectric constant solvent such as cyclic carbonates or cyclic carboxylic acid esters in combination with a low viscosity solvent such as chain carbonates or chain carboxylic acid esters.

  One preferable combination of the non-aqueous solvents is a combination mainly composed of alkylene carbonate and dialkyl carbonate. Among them, the total of alkylene carbonate and dialkyl 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 alkylene carbonate and dialkyl carbonate. The proportion of the alkylene carbonate with respect to the total of 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, still more preferably Is 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.

As the alkylene carbonate, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate are preferable from the viewpoint of improving the cycle characteristics and high-temperature storage characteristics of the battery.
Specific examples of preferred combinations of ethylene carbonate and dialkyl 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 methyl. Examples thereof include 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 a combination of these ethylene carbonate and dialkyl carbonates is also mentioned as 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 whole 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 dialkyl carbonate, those containing asymmetrical chain alkyl carbonates as dialkyl carbonate are more preferred, especially ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate. Those containing ethylene carbonate, symmetric chain alkyl carbonates, and asymmetric chain alkyl carbonates such as 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 alkyl carbonate is preferably ethyl methyl carbonate, and the alkyl group of the alkyl carbonate preferably has 1 to 2 carbon atoms.

  Specific examples of preferred combinations of fluoroethylene carbonate and dialkyl carbonate include fluoroethylene carbonate and dimethyl carbonate, fluoroethylene carbonate and diethyl carbonate, fluoroethylene carbonate and ethyl methyl carbonate, fluoroethylene carbonate and dimethyl carbonate and diethyl carbonate, and fluoroethylene carbonate. And dimethyl carbonate and ethyl methyl carbonate, fluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

A combination obtained by further adding ethylene carbonate and / or propylene carbonate to the combination of these fluoroethylene carbonate and dialkyl carbonate is also mentioned as a preferable combination.
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. It is particularly preferably 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.

  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. It is particularly preferably 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 capacity 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 electrical conductivity of the electrolyte and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more. The capacity 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.

  Further, in the combination mainly composed of the alkylene carbonates and dialkyl carbonates, cyclic carbonates other than the alkylene carbonates and dialkyl carbonates, chain carbonates, cyclic carboxylic acid esters, chain carboxylic acid esters, Other solvents such as cyclic ethers, chain ethers, sulfur-containing organic solvents, phosphorus-containing organic solvents, and aromatic fluorine-containing solvents may be mixed.

Another example of the preferred non-aqueous solvent is an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, or a mixed solvent consisting of two or more organic solvents selected from the group. It occupies 60% by volume or more. A non-aqueous electrolyte using this mixed solvent may reduce solvent evaporation and liquid leakage even when used at high temperatures. Among them, the total of ethylene carbonate and propylene carbonate in the non-aqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and the capacity 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 capacity of the non-aqueous solvent is a measured value at 25 ° C., but a measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.

(Other compounds)
The nonaqueous electrolytic solution according to the present invention is a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate, and a difluorophosphate within a range not impairing the effects of the present invention. Various other compounds such as at least one compound selected from the group consisting of and a conventionally known overcharge inhibitor may be contained as an auxiliary agent.

  Among these, when containing at least one compound selected from the group consisting of a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate, and a difluorophosphate, a negative electrode In order to form a highly stable film, cycle characteristics and battery characteristics after high-temperature storage may be improved, which is preferable.

((Cyclic carbonate compound having a carbon-carbon unsaturated bond))
Examples of the cyclic carbonate compound having a carbon-carbon unsaturated bond include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 1,2-dimethyl vinylene carbonate, 1,2-diethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl. Vinylene carbonate compounds such as vinylene carbonate; vinyl ethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-2-vinylethylene carbonate, 1-n-propyl-2-vinylethylene carbonate, 1-methyl-2- Vinyl ethylene carbonate compounds such as vinyl ethylene carbonate, 1,1-divinyl ethylene carbonate, 1,2-divinyl ethylene carbonate; 1,1-dimethyl-2- Chi Ren ethylene carbonate, methylene ethylene carbonate compounds such as 1,1-diethyl-2-methylene-ethylene carbonate. Among these, vinylene carbonate, vinyl ethylene carbonate, and 1,2-divinyl ethylene carbonate are preferable from the viewpoint of improving cycle characteristics and capacity maintenance characteristics after high-temperature storage, among which vinylene carbonate or vinyl ethylene carbonate is more preferable, and vinylene carbonate is particularly preferable. preferable. These may be used alone or in combination of two or more.
When using 2 or more types together, it is preferable to use together vinylene carbonate and vinyl ethylene carbonate.

((Cyclic carbonate compound having fluorine atom))
Examples of the cyclic carbonate compound having a fluorine atom include fluoroethylene carbonate, 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, tetrafluoroethylene carbonate, 1- Fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate Etc. Of these, fluoroethylene carbonate, 1,2-difluoroethylene carbonate, and 1-fluoro-2-methylethylene carbonate are preferable from the viewpoint of improving cycle characteristics and high-temperature storage characteristics. These may be used alone or in combination of two or more.
In addition, it may be used in combination with a cyclic carbonate compound having a carbon-carbon unsaturated bond and the monofluorophosphate and difluorophosphate described below. Is preferred.

((Monofluorophosphate and difluorophosphate))
The counter cation of monofluorophosphate and difluorophosphate is not particularly limited, but lithium, sodium, potassium, magnesium, calcium, and NR ¹ R ² R ³ R ⁴ (wherein R ^{1 to} R ⁴ Are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms.)

Although there is no particular limitation on the organic group having 1 to 12 carbon atoms represented by R ¹ to R ⁴ of the above ammonium, for example, which may be substituted with a halogen atom an alkyl group, substituted with a halogen atom or an alkyl group 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 ^{1 to} R ⁴ , a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group is preferable.

  Specific examples of monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, tetramethylammonium monofluorophosphate, tetraethylammonium monofluorophosphate, difluoro Examples include lithium phosphate, sodium difluorophosphate, potassium difluorophosphate, tetramethylammonium difluorophosphate, tetraethylammonium difluorophosphate, etc., preferably lithium monofluorophosphate and lithium difluorophosphate, more preferably lithium difluorophosphate. preferable.

These may be used alone or in combination of two or more.
Moreover, you may use together with the cyclic carbonate compound which has a carbon-carbon unsaturated bond, and the cyclic carbonate compound which has a fluorine atom, and it is preferable to use together from the point of a cycling characteristic improvement or the characteristic improvement after high temperature storage.
When the non-aqueous electrolyte contains a cyclic carbonate compound having a carbon-carbon unsaturated bond, the proportion in the non-aqueous electrolyte is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, More preferably, it is 0.1 mass% or more, Most preferably, it is 0.3 mass% or more. If the proportion of the cyclic carbonate compound having a carbon-carbon unsaturated bond is too small, the effect of improving the cycle characteristics of the battery and the capacity maintenance characteristics after high-temperature storage may not be sufficiently exhibited. However, if the ratio of the cyclic carbonate compound having a carbon-carbon unsaturated bond is too large, the amount of gas generated may increase during storage at high temperatures, or the discharge characteristics at low temperatures may decrease. More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less.

  When the non-aqueous electrolyte contains a cyclic carbonate compound having a fluorine atom as an auxiliary agent, the proportion in the non-aqueous electrolyte is preferably 0.001% by mass or more, more preferably 0.1% by mass or more, and further Preferably it is 0.3% by mass or more, particularly preferably 0.5% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, particularly preferably 3% by mass. It is as follows.

If the ratio is less than the above range, there is a possibility that the effect of improving the cycle characteristics and high temperature storage characteristics of the battery may not be sufficiently exhibited.If the ratio exceeds the above range, the amount of gas generated during high temperature storage may increase, The discharge characteristics may deteriorate.
When the non-aqueous electrolyte contains a monofluorophosphate and / or difluorophosphate, the proportion in the non-aqueous electrolyte is preferably 0.001% by mass or more, more preferably 0.01% by mass or more. More preferably, it is 0.1% by mass or more, particularly preferably 0.2% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less.

If the ratio is less than the above range, there is a possibility that the effect of improving the cycle characteristics and high-temperature storage characteristics of the battery may not be fully exhibited. Tend.
Conventionally known overcharge inhibitors include alkylbiphenyls such as biphenyl, 2-methylbiphenyl, 2-ethylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4 -Phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran , Methylphenyl carbonate, ethylphenyl carbonate, diphenyl carbonate, triphenyl phosphate, tris (2-t-butylphenyl) phosphate, tris (3-t-butylphenyl) phosphate , Tris (4-t-butylphenyl) phosphate, tris (2-t-amylphenyl) phosphate, tris (3-t-amylphenyl) phosphate, tris (4-t-amylphenyl) phosphate, tris (2-cyclohexyl) Aromatic compounds such as phenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate; 2-fluorobiphenyl, 3-fluorobiphenyl, 4-fluorobiphenyl, 4,4′-difluorobiphenyl, Partially fluorinated products of the above aromatic compounds such as 2,4-difluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-diph Oroanisoru, fluorinated anisole compound such as 3,5-difluoro anisole, and the like.

  Among these, alkylbiphenyl such as biphenyl and 2-methylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4- Phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, methylphenyl carbonate, diphenyl carbonate, triphenyl phosphate, Aromatic compounds such as tris (4-t-butylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate; 2-fluorobiphenyl, 3-fluorobiphenyl , 4-fluorobiphenyl, 4,4′-difluorobiphenyl, partial fluorinated products of the above aromatic compounds such as o-cyclohexyl fluorobenzene, p-cyclohexyl fluorobenzene, etc. are preferable, partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexyl Benzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene , T-amylbenzene, methylphenyl carbonate, diphenyl carbonate, triphenyl phosphate, tris (4-t-butylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, o Cyclohexyl fluorobenzene, more preferably p- cyclohexyl fluorobenzene, partially hydrogenated member and cyclohexylbenzene terphenyl is particularly preferred.

  Two or more of these may be used in combination. When two or more types are used in combination, in particular, a partially hydrogenated terphenyl, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, or a partially hydrogenated biphenyl, alkylbiphenyl, terphenyl or terphenyl. It is overcharged to use together those selected from oxygen-free aromatic compounds such as cyclohexylbenzene, t-butylbenzene, t-amylbenzene and those selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran. This is preferable from the viewpoint of the balance between prevention characteristics and high-temperature storage characteristics.

  The content ratio of these overcharge inhibitors in the non-aqueous electrolyte is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and particularly preferably 0%. 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. If the concentration is too low, the desired effect of the overcharge inhibitor may hardly be exhibited. On the other hand, if the concentration is too high, battery characteristics such as high-temperature storage characteristics tend to deteriorate.

  Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate, methoxyethyl-ethyl carbonate, ethoxyethyl-methyl carbonate, ethoxyethyl-ethyl carbonate; succinic anhydride Carboxylic acids such as glutaric anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, glutaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride Anhydride: dimethyl succinate, diethyl succinate, diallyl succinate, dimethyl maleate, diethyl maleate, diallyl maleate, dipropyl maleate, dibutyl maleate, bis maleate (trifluoro Dicarboxylic acid diester compounds such as bis (pentafluoroethyl) maleate, bis (2,2,2-trifluoroethyl) maleate; 2,4,8,10-tetraoxaspiro [5.5] undecane Spiro compounds such as 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, propylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, methyl methanesulfonate, ethyl methanesulfonate, methyl-methoxymethanesulfonate, methyl-2-methoxyethanesulfonate, busulfan, diethylene glycol dimethanesulfonate, 1,2-ethanediol bis ( 2,2,2-Trifluo Ethanesulfonate), 1,4-butanediol bis (2,2,2-trifluoroethanesulfonate), sulfolane, 3-sulfolene, 2-sulfolene, dimethylsulfone, diethylsulfone, divinylsulfone, diphenylsulfone, bis (methylsulfonyl) ) Methane, bis (methylsulfonyl) ethane, bis (ethylsulfonyl) methane, bis (ethylsulfonyl) ethane, bis (vinylsulfonyl) methane, bis (vinylsulfonyl) ethane, N, N-dimethylmethanesulfonamide, N, N -Sulfur-containing compounds such as diethylmethanesulfonamide, N, N-dimethyltrifluoromethanesulfonamide, N, N-diethyltrifluoromethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl Nitrogen-containing compounds such as 2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; heptane, octane, nonane, decane, cycloheptane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, n -Hydrocarbon compounds such as butylcyclohexane, t-butylcyclohexane, dicyclohexyl; fluorinated benzenes such as fluorobenzene, difluorobenzene, pentafluorobenzene, hexafluorobenzene; 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, Fluorinated toluene such as benzotrifluoride; Nitto such as acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, etc. Methyl dimethyl phosphinate, ethyl dimethyl phosphinate, ethyl diethyl phosphinate, trimethylphosphonoformate, triethylphosphonoformate, trimethylphosphonoacetate, triethylphosphonoacetate, trimethyl-3-phosphonopropionate, Examples thereof include phosphorus-containing compounds such as triethyl-3-phosphonopropionate. Among these, ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, busulfan, 1,4 in terms of improving battery characteristics after high-temperature storage -Sulfur-containing compounds such as butanediol bis (2,2,2-trifluoroethanesulfonate); nitrile compounds such as acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are preferable.

Two or more of these may be used in combination.
The content of these auxiliary agents in the non-aqueous electrolyte solution is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more. Yes, preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 1% by mass or less. The addition of these auxiliaries is preferable in terms of improving capacity maintenance characteristics and cycle characteristics after high-temperature storage. If the concentration is lower than this lower limit, the effect of the auxiliary agent may be hardly exhibited. Conversely, if the concentration is too high, battery characteristics such as high load discharge characteristics may be degraded.

(Preparation of electrolyte)
The nonaqueous electrolytic solution according to the present invention can be prepared by dissolving an electrolyte, a compound represented by the general formula (I), and, if necessary, other compounds in a nonaqueous solvent. In preparing the non-aqueous electrolyte solution, each raw material is preferably dehydrated in advance in order to reduce the water content when the electrolyte solution is used. The dehydration is preferably performed to 50 ppm or less, more preferably 30 ppm or less, and even more preferably 10 ppm or less. Moreover, you may implement dehydration, a deoxidation process, etc. after electrolyte solution preparation.

  The non-aqueous electrolyte solution of the present invention is suitable for use as a non-aqueous electrolyte solution for a secondary battery, that is, a non-aqueous electrolyte secondary battery, for example, a lithium secondary battery, among non-aqueous electrolyte batteries. Hereinafter, a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte of the present invention will be described.

<Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery of the present invention is 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, and the non-aqueous electrolyte is a non-aqueous electrolyte of the present invention. It is an aqueous electrolyte solution.
(Battery configuration)
The non-aqueous electrolyte secondary battery according to the present invention can occlude and release lithium ions as in the case of a conventionally known non-aqueous electrolyte secondary battery except that it is produced using the non-aqueous electrolyte of the present invention. A non-aqueous electrolyte battery including a negative electrode and a positive electrode and a non-aqueous electrolyte solution. Usually, the positive electrode and the negative electrode are accommodated in a case through a porous film impregnated with the non-aqueous electrolyte solution of the present invention. can get. Therefore, the shape of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it can occlude and release lithium ions. Specific examples thereof include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like.
These negative electrode active materials may be used alone or in combination of two or more. Of these, carbonaceous materials and alloy materials are preferred.
Among the carbonaceous materials, amorphous carbon materials, graphite, and those in which the surface of graphite is coated with amorphous carbon compared to graphite are preferred, and in particular, the surface of graphite or graphite is amorphous compared to graphite. Those coated with carbon are generally preferred because of their high energy density.

  Graphite preferably has a lattice plane (002 plane) d value (interlayer distance) of 0.335 to 0.338 nm, particularly 0.335 to 0.337 nm, as determined by X-ray diffraction using the Gakushin method. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is preferably 10 nm or more, more preferably 50 nm or more, and still more preferably 100 nm or more. The ash content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less.

  The graphite surface coated with amorphous carbon is preferably graphite having a d-value of 0.335 to 0.338 nm on the lattice plane (002 plane) in X-ray diffraction as a core material. A carbonaceous material having a larger d-value on the lattice plane (002 plane) in X-ray diffraction than the core material is attached, and the d-value on the lattice plane (002 plane) in X-ray diffraction is greater than that of the core material and the core material. The ratio with respect to the carbonaceous material having a large is 99/1 to 80/20 in mass ratio. When this is used, a negative electrode having a high capacity and hardly reacting with the electrolytic solution can be produced.

The particle size of the carbonaceous material is a median diameter by a laser diffraction / scattering method, preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, particularly preferably 7 μm or more, preferably 100 μm or less, more preferably Is 50 μm or less, more preferably 40 μm or less, and particularly preferably 30 μm or less.
The specific surface area of the carbonaceous material by the BET method is preferably 0.3 m ² / g or more, more preferably 0.5 m ² / g or more, still more preferably 0.7 m ² / g or more, and particularly preferably 0.8 m ^2. / g or more, preferably 25.0 m ² / g or less, more preferably 20.0 m ² / g or less, more preferably 15.0 m ² / g or less, particularly preferably not more than 10.0 m ² / g .

Further, the carbonaceous material is analyzed by Raman spectrum using argon ion laser light, the peak is the peak intensity of the peak _{P A} in the range of 1570~1620cm ^-1 _I A, in the range of 1300~140cm ^-1 P If the peak intensity of the _B was _{I B,} R value represented by the ratio of _{I B} and _{I a (= I B / I} a) is what is preferably in the range of 0.01 to 0.7. Further, the half width of the peak in the range of 1570～1620Cm ^-1 is, 26cm ^-1 or less, are preferred in particular 25 cm ^-1 or less.

  The alloy material is not particularly limited as long as it can occlude / release lithium, and single metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, sulfides, and phosphides thereof. Any of these compounds may be used. Preferably, it is a material containing a single metal and an alloy forming a lithium alloy, more preferably a material containing a group 13 and group 14 metal / metalloid element (that is, excluding carbon), and further, aluminum, silicon, and It is preferably a simple metal of tin (which may be hereinafter referred to as “specific metal element”), and an alloy or compound containing these elements.

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

  Moreover, the compound which these complex compounds combined with several elements, such as a metal simple substance, an alloy, or a nonmetallic element, can also be mentioned as an example. More 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. In addition, 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 can also be used. .

Among these negative electrode active materials, since the capacity per unit mass is large when a battery is formed, any one metal element of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element A material, carbide, nitride or the like is preferable, and silicon and / or tin metal alone, an alloy, an oxide, carbide, nitride, or the like is particularly preferable because of its large capacity per unit mass.
In addition, although the capacity per unit mass is inferior to that of using a single metal or an alloy, the following compounds containing silicon and / or tin are also preferred because of excellent cycle characteristics.

The element ratio of silicon and / or tin to oxygen is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, and preferably 1.5 or less, more preferably Silicon and / or tin oxides of 1.3 or less, more preferably 1.1 or less.
The element ratio of silicon and / or tin and nitrogen is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, and preferably 1.5 or less, more preferably Silicon and / or tin nitride of 1.3 or less, more preferably 1.1 or less.

The element ratio of silicon and / or tin to carbon is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, and preferably 1.5 or less, more preferably Silicon and / or tin carbides of 1.3 or less, more preferably 1.1 or less.
These alloy materials may be in the form of powder or thin film, and may be crystalline or amorphous.

  The average particle size of the alloy-based material is not particularly limited in order to exhibit the effects of the present invention, but is preferably 50 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less, preferably 0.1 μm or more, More preferably, it is 1 micrometer or more, More preferably, it is 2 micrometers or more. If the particle size is too large, the expansion of the electrode is increased, and the cycle characteristics may be deteriorated. Moreover, when too small, it will become difficult to collect current, and capacity | capacitance may not fully express.

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. However, a lithium-titanium composite oxide (hereinafter referred to as “lithium-titanium composite oxide”) (Abbreviated) is preferred.
In addition, a part of lithium or titanium in the lithium titanium composite oxide is selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with at least one element are also preferred.

Furthermore, it is a lithium titanium composite oxide represented by Li _x Ti _y M _z O ₄ , and 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, and 0 ≦ z ≦ 1.6. It is preferable that the structure at the time of occlusion / release of lithium ions is stable (M is a group consisting of Na, K, Co, Al, Fe, Mg, Cr, Ga, Cu, Zn, and Nb). Represents at least one element selected).

Among them, when Z = 0 of the lithium titanium composite oxide represented by Li _x Ti _y M _z O ₄ , the structure in the case where x and y satisfy any of the following (a) to (c): This is preferable because of a good balance of battery performance.
(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
More preferred representative compositions 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 ₄ in (c). .
As for the structure when Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.

(Positive electrode active material)
The positive electrode active material is not particularly limited as long as it can occlude and release lithium ions. A substance containing lithium and at least one transition metal is preferable, and examples thereof include a lithium transition metal composite oxide and a lithium-containing transition metal phosphate compound.
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 . Examples of the lithium / nickel composite oxide include lithium / manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ , and Li ₂ MnO ₃ . In addition, a part of the transition metal atom that is the main component of the lithium transition metal composite oxide is replaced with another metal, that is, a part of Co in the lithium-cobalt composite oxide is replaced with Al, Ti, V, Cr. , Mn, Fe, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si substituted with other metals, part of Ni in the lithium-nickel composite oxide is Al, Ti, V, Cr, Substituted with other metals such as Mn, Fe, Co, Li, Cu, Zn, Mg, Ga, Zr, Si, and a part of Mn of the lithium-manganese composite oxide Al, Ti, V, Cr, Fe , Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si substituted with other metals, and the like. Among those in which a part of the transition metal atom that is the main component of the lithium transition metal composite oxide is substituted with another metal, LiNi _1-ab Mn _a Co _b O ₂ (a and b are 0 or more and less than 1) Li, except for the case where a and b are both 0), LiNi _1-c- De Co _C Al _d Mg _e O ₂ (c, d, e represents a number from 0 to less than 1, , D, and e are preferably 0), and LiNi _{1 -ab} Mn _a Co _b O ₂ (0 ≦ a <0.4, 0 ≦ b <0.4), LiNi _{1− c-d-e Co c Al} d Mg e O 2 (0 ≦ c <0.3,0 ≦ d <0.1,0 ≦ e <0.05) are preferred, in _{particular, LiNi} 1/3 _{Co 1 / 3} Mn _1/3 O ₂ , LiNi _0.5 Co _0.3 Mn _0.2 O ₂ , LiNi _0.5
Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , and LiNi _0.85 Co _0.10 Al _0.03 Mg _0.02 O ₂ are preferable.

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 F ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O _{7 and} cobalt phosphates such as LiCoPO ₄ . In addition, a part of the transition metal atom that is the main component of the lithium transition metal phosphate compound is substituted with another metal, that is, a part of Fe of iron phosphates is Al, Ti, V, Cr, Mn, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and other metals substituted, Co cobalt phosphates part of Co Al, Ti, V, Cr, Mn, Fe , Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si substituted with other metals, and the like.

These positive electrode active materials may be used alone or in combination.
In addition, a material in which a substance (surface adhering substance) having a composition different from that of the substance constituting the main cathode active material is attached to the surface of the cathode active material can be used. 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.

  The amount of the surface adhering substance is not particularly limited in order to exhibit the effect of the present invention, but is preferably 0.1 ppm or more, more preferably 1 ppm or more, and still more preferably, by mass with respect to the positive electrode active material. It is used at 10 ppm or more, preferably 20% or less, more preferably 10% or less, and still more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte solution on the surface of the positive electrode active material, and can improve the battery life. However, when the amount of the adhering quantity is too small, the effect is not sufficiently exhibited. If the amount is too large, the resistance may increase in order to inhibit the entry and exit of lithium ions.

(Manufacture of electrodes)
As the binder for binding the active material, any material can be used as long as it is a material that is stable with respect to the solvent and the electrolyte used in manufacturing the electrode. For example, fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, polyolefins such as polyethylene and polypropylene, polymers having unsaturated bonds such as styrene / butadiene rubber, isoprene rubber and butadiene rubber, ethylene-acrylic acid copolymers, An acrylic acid polymer such as an ethylene-methacrylic acid copolymer may be used.

The electrode may contain a thickener, a conductive material, a filler and the like in order to increase mechanical strength and electrical conductivity.
Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.

Examples of the conductive material include metal materials such as copper and nickel, and carbon materials such as graphite and carbon black.
The electrode may be manufactured by a conventional method. For example, it can be formed by adding a binder, a thickener, a conductive material, a solvent or the like to a negative electrode or a positive electrode active material to form a slurry, applying the slurry to a current collector, drying it, and then pressing it.

In addition, a material obtained by adding a binder or a conductive material to an active material is roll-formed as it is to form a sheet electrode, a pellet electrode is formed by compression molding, and an electrode is formed on the current collector by techniques such as vapor deposition, sputtering, or plating. A thin film of material can also be formed.
When graphite is used for the negative electrode active material, the density of the negative electrode active material layer after drying and pressing is preferably 1.45 g / cm ³ or more, more preferably 1.55 g / cm ³ or more, and even more preferably 1.60 g. / Cm ³ or more, particularly preferably 1.65 g / cm ³ or more.

The density after drying and pressing of the positive electrode active material layer is preferably 2.0 g / cm ³ or more, more preferably 2.5 g / cm ³ or more, and further preferably 3.0 g / cm ³ or more.
Various types of current collectors can be used, but metals and alloys are usually used. Examples of the current collector for the negative electrode include copper, nickel, and stainless steel, and copper is preferred. Examples of the positive electrode current collector include metals such as aluminum, titanium, and tantalum, and alloys thereof, and aluminum or an alloy thereof is preferable.

(Separator, exterior body)
A porous film (separator) is interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the electrolytic solution is used by impregnating the porous membrane. The material and shape of the porous film are not particularly limited as long as it is stable to the electrolytic solution and excellent in liquid retention, and a porous sheet or nonwoven fabric made of a polyolefin such as polyethylene or polypropylene is preferable.
The material of the battery casing used in the battery according to the present invention is also arbitrary, and nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, a laminate film, or the like is used.
The operating voltage of the above-described non-aqueous electrolyte secondary battery of the present invention is usually in the range of 2V to 4.9V.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.
In addition, each evaluation method of the battery obtained by the following Example and the comparative example is shown below.
[Capacity evaluation]
The sheet-like non-aqueous electrolyte secondary battery was charged to 4.2 V with a constant current corresponding to 0.2 C at 25 ° C. in a state of being sandwiched between glass plates in order to enhance the adhesion between the electrodes, and then 0 The battery was discharged to 3V with a constant current of 2C. This is done for 3 cycles to stabilize the battery. In the 4th cycle, after charging to 4.2V with a constant current of 0.5C, charging is performed until the current value reaches 0.05C with a constant voltage of 4.2V. The initial discharge capacity was determined by discharging to 3 V at a constant current of 0.2C.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[Overcharge characteristics evaluation]
After the capacity evaluation test was completed, the battery was immersed in an ethanol bath and the volume was measured. Then, the battery was charged at a constant current of 0.2 C to 4.9 V at 45 ° C., and reached 4.9 V. The current was cut, and the open circuit voltage (OCV) of the battery after the overcharge test was measured.
Next, the volume was measured by immersion in an ethanol bath, and the amount of gas generated from the volume change before and after overcharging was determined.
The lower the OCV of the battery after the overcharge test, the lower the overcharge depth and the higher the safety during overcharge.
Further, the larger the amount of gas generated after overcharging, the more preferable the battery that senses this when the internal pressure rises abnormally due to an abnormality such as overcharging and operates the safety valve because the safety valve can be activated earlier. .

  Also, the greater the difference between the amount of gas generated after overcharging and the amount of gas generated during high-temperature continuous charging, etc., will cause the safety valve to malfunction during high-temperature continuous charging while reliably operating the safety valve during overcharging. Since it can prevent, it is preferable.

[Evaluation of high-temperature continuous charge characteristics]
After the capacity evaluation test was completed, the volume was measured by immersing the battery in an ethanol bath. Then, constant current charging was performed at a constant current of 0.5 C at 60 ° C., and after reaching 4.25 V, constant voltage charging was performed. Switching was performed continuously for one week.
After the continuous charge test, the battery was cooled to 25 ° C. and then immersed in an ethanol bath to measure the volume, and the amount of gas generated from the volume change before and after the continuous charge was determined.
After measuring the amount of gas generated, discharge to 3 V at a constant current of 0.2 C at 25 ° C., measure the remaining capacity after the continuous charge test, and determine the ratio of the discharge capacity after the continuous charge test to the initial discharge capacity. Was the remaining capacity (%) after the continuous charge test.

  Next, after charging to 4.2V at a constant current of 0.5C at 25 ° C, charging is carried out until the current value reaches 0.05C at a constant voltage of 4.2V, and discharged to 3V at a constant current of 1C. Then, the 1C discharge capacity after the continuous charge test was measured, the ratio of the 1C discharge capacity after the continuous charge test to the initial discharge capacity was determined, and this was defined as the 1C capacity (%) after the continuous charge test.

Example 1
[Manufacture of negative electrode]
The d-value of the lattice plane (002 plane) in X-ray diffraction is 0.336 nm, the crystallite size (Lc) is 652 nm, the ash content is 0.07 parts by mass, the median diameter by laser diffraction / scattering method is 12 μm, and the ratio by BET method The half-value width of a peak whose surface area is 7.5 m ² / g and the R value (= I _B / I _A ) determined from Raman spectrum analysis using an argon ion laser beam is in the range of 0.12, 1570 to 1620 cm ^−1. 19.9 cm ⁻¹ of natural graphite powder 94 parts by mass and polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd., trade name “KF-1000”) 6 parts by mass are mixed, and N-methyl-2-pyrrolidone is added to the slurry. I made it. This slurry was uniformly applied to one side of a 12 μm thick copper foil and dried, and then pressed to obtain a negative electrode active material layer having a density of 1.67 g / cm ³ to form a negative electrode.

[Production of positive electrode]
90 parts by mass of LiCoO ₂ , 4 parts by mass of carbon black and 6 parts by mass of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd., trade name “KF-1000”) are mixed, and N-methyl-2-pyrrolidone is added to form a slurry. Was applied uniformly on both sides of an aluminum foil having a thickness of 15 μm and dried, and then pressed so that the density of the positive electrode active material layer was 3.2 g / cm ³ to obtain a positive electrode.

[Manufacture of electrolyte]
In a dry argon atmosphere, a mixture of ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate (volume ratio 2: 3: 3), as shown in Table 1, 2% by mass of vinylene carbonate and methane as the content in the non-aqueous electrolyte solution 1% by mass of sulfonic acid (4-cyclohexylphenyl) was mixed, and then sufficiently dried LiPF ₆ was dissolved at a ratio of 1.0 mol / liter to obtain an electrolytic solution.

[Manufacture of non-aqueous electrolyte secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode to produce a battery element. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then the electrolyte was poured into the bag and vacuum sealed. The sheet-like battery was manufactured and the overcharge characteristics and the high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 2)
In the electrolytic solution of Example 1, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, methanesulfonic acid (4-t-amylphenyl) was used as in Example 1, except that methanesulfonic acid (4-t-amylphenyl) was used. Sheet-like batteries were prepared, and overcharge characteristics and high-temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 3)
As shown in Table 1, a mixture of ethylene carbonate, ethylmethyl carbonate, and dimethyl carbonate (volume ratio 2: 3: 3), as shown in Table 1, contains 2% by weight of vinylene carbonate, 0.2% of lithium difluorophosphate. 5% by mass and 1% by mass of methanesulfonic acid (4-cyclohexylphenyl) were mixed. Next, a sheet-like battery was prepared in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried at a ratio of 1.0 mol / liter was used. The high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 4)
In the electrolytic solution of Example 3, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, methanesulfonic acid (4-t-amylphenyl) was used as in Example 3, except that methanesulfonic acid (4-t-amylphenyl) was used. A sheet-like battery was prepared, and overcharge characteristics and high-temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 5)
As shown in Table 1, a mixture of ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate (volume ratio 2: 3: 3), as shown in Table 1, vinylene carbonate 1% by mass, fluoroethylene carbonate 1% by mass And 1% by mass of methanesulfonic acid (4-cyclohexylphenyl) were mixed. Next, a sheet-like battery was prepared in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried at a ratio of 1.0 mol / liter was used. The high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Example 6)
In the electrolytic solution of Example 1, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, ethanesulfonic acid (4-cyclohexylphenyl) was used as shown in Table 1, and the same sheet as in Example 1 was used. A battery was fabricated and evaluated for overcharge characteristics and high-temperature continuous charge characteristics. The evaluation results are shown in Table 2.

(Comparative Example 1)
As shown in Table 1, 2% by mass of vinylene carbonate as a content in the non-aqueous electrolyte was mixed with a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate (volume ratio 2: 3: 3). Next, a sheet-like battery was prepared in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried at a ratio of 1.0 mol / liter was used. The high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Comparative Example 2)
In the electrolytic solution of Example 1, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, a sheet-like battery was produced in the same manner as in Example 1 except that phenylcyclohexane was used. The overcharge characteristics and the high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Comparative Example 3)
In the electrolytic solution of Example 1, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, a sheet-like battery was produced in the same manner as in Example 1 except that phenylmethanemethanesulfonate was used. The overcharge characteristics and the high temperature continuous charge characteristics were evaluated. The evaluation results are shown in Table 2.

(Comparative Example 4)
In the electrolytic solution of Example 1, instead of methanesulfonic acid (4-cyclohexylphenyl), as shown in Table 1, except that methanesulfonic acid (4-methylphenyl) was used, a sheet was obtained in the same manner as Example 1. A battery was fabricated and evaluated for overcharge characteristics and high-temperature continuous charge characteristics. The evaluation results are shown in Table 2.

  As is clear from Table 2, the batteries of Comparative Examples 1, 3, and 4 are excellent in the amount of generated gas after high-temperature continuous charging, the remaining capacity and the 1C discharge capacity, but the amount of generated gas after overcharging is small, Low safety during overcharge. The battery of Comparative Example 2 has a large amount of generated gas after overcharging and high safety during overcharging, but is inferior in the amount of generated gas, remaining capacity and 1C discharge capacity after high-temperature continuous charging. In contrast, the batteries of Examples 1 to 6 have a large amount of gas generation after overcharging, high safety during overcharging, and excellent gas generation amount, remaining capacity and 1C discharge capacity after high-temperature continuous charging. . Therefore, it can be seen that the battery using the non-aqueous electrolyte according to the present invention has high safety during overcharge and is excellent in high-temperature continuous charge characteristics.

  The non-aqueous electrolyte battery using the non-aqueous electrolyte of the present invention has high capacity and excellent high-temperature continuous charge characteristics while improving safety during overcharge, and therefore can be used for various known applications. Is possible. 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 A power source for leveling, a natural energy storage power source, and the like can be given.

Claims (6)

In a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent, the non-aqueous electrolyte solution contains a compound represented by the general formula (I), and is further selected from the group consisting of monofluorophosphate and difluorophosphate A non-aqueous electrolyte containing a kind of compound .

(In General Formula (I), R ₁ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, and R _{2 to} R ₆ are each independently a hydrogen atom, a fluorine atom, or a fluorine atom. Represents an alkyl group having 1 to 12 carbon atoms which may be substituted with an atom, provided that at least one of R _{2 to} R ₆ represents an alkyl group having 2 or more carbon atoms which may be substituted with a fluorine atom. Represents an integer of 1 (except that at least one of R _{2 to} R ₆ is a cyclohexyl group) . In General Formula (1), R ₁ represents a group selected from the group consisting of a methyl group, an ethyl group, a vinyl group, a phenyl group, and a trifluoromethyl group, and R _{2 to} R ₆ are each independently a hydrogen atom. Or the C2-C6 alkyl group which may be substituted by the fluorine atom is represented, The nonaqueous electrolyte solution of Claim 1 characterized by the above-mentioned. 3. The non-aqueous system according to claim 1, wherein at least one of R _{2 to} R ₆ in formula (I) represents an alkyl group having 4 or more carbon atoms which may be substituted with a fluorine atom. Electrolytic solution.   4. The non-aqueous electrolyte solution according to claim 1, wherein the ratio of the compound represented by the general formula (I) in the non-aqueous electrolyte solution is 0.001 to 10% by mass. Furthermore, carbon - carbon cyclic carbonate compound having an unsaturated bond, and fluorine atoms having cyclic carbonate compound or the Ranaru group of at least one selected of claims 1 to 4, characterized by containing the compound The non-aqueous electrolyte solution in any one.   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 the non-aqueous electrolyte solution according to any one of claims 1 to 5. A non-aqueous electrolyte battery characterized by that.