JP2023054761A - Nonaqueous electrolyte and nonaqueous electrolyte battery including the same - Google Patents

Abstract

To provide a nonaqueous electrolyte and a nonaqueous electrolyte battery excellent in the capacity retention rate on repeated charging/discharging and the gas suppression upon high temperature charge storage.SOLUTION: The nonaqueous electrolyte contains a compound represented by the following general formula (1). (In general formula (1), R1 and R2 are each independently a hydrogen atom or a hydrocarbon group, and X represents a divalent hydrocarbon group comprising a ring together with a -O-Si-O- bond. However, the hydrogen atom possessed by the carbon of X may be substituted with a halogen atom.)SELECTED DRAWING: None

Description

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

2. Description of the Related Art 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 vehicle power sources for driving automobiles and the like. However, in recent years, the demand for higher performance of non-aqueous electrolyte batteries has been increasing. improvement is desired. As a means for improving these characteristics, many techniques have been studied for various battery components including positive and negative electrode active materials and non-aqueous electrolyte solutions.

For example, Patent Literature 1 discloses a study of improving cycle characteristics by adding a specific silane compound to a non-aqueous electrolytic solution. Patent Literature 2 discloses a study of adding a specific alkoxysilane compound to a non-aqueous electrolytic solution to improve cycle capacity retention rate and volume change during high-temperature storage. Patent Document 3 discloses a study of improving the resistance increase rate and the capacity retention rate after cycles by adding a trialkoxysilane compound to a non-aqueous electrolytic solution. Patent Literatures 4 and 5 disclose a study to improve battery swelling and internal resistance by adding a vinyltrialkoxysilane compound to a non-aqueous electrolytic solution. Patent Documents 6 to 9 disclose studies to improve the capacity retention rate, gas, low temperature resistance, etc. after charging and storage by adding a silane compound having a carbon-carbon unsaturated bond to a non-aqueous electrolyte. there is

U.S. Patent Application Publication No. 2020/0388876 International Publication No. 2018/028392 U.S. Patent Application Publication No. 2019/0288336 JP 2013-175409 A JP 2013-175410 A International Publication No. 2017-138452 International Publication No. 2017-138453 International Publication No. 2019-117101 International Publication No. 2019-111983

When the inventors of the present invention examined the method described in the above document, they found that there was a problem that the capacity retention rate during repeated charging and discharging of the non-aqueous electrolyte battery was not sufficient.

Accordingly, an object of the present invention is to provide a non-aqueous electrolytic solution and a battery that improve the capacity retention rate during repeated charging and discharging of the non-aqueous electrolytic solution battery. In addition, it is possible to suppress the amount of gas generated during high-temperature storage when a battery is made using the present electrolytic solution. An object of the present invention is to provide a non-aqueous electrolytic solution and a battery that can suppress the

In view of the above-mentioned circumstances, the present inventors have made intensive studies and found that the above objects can be achieved by using a non-aqueous electrolytic solution containing the compound represented by the general formula (1). completed.

（一般式（１）中、Ｒ^１及びＲ^２はそれぞれ独立に水素原子または炭化水素基であり、Ｘは－Ｏ－Ｓｉ－Ｏ－結合とともに環を構成する２価の炭化水素基を表す。ただし、Ｘの炭素が有する水素原子はハロゲン原子で置換されていてもよい。） That is, the gist of the present invention resides in the following.
[1] A non-aqueous electrolytic solution containing a compound represented by the following general formula (1).

(In general formula (1), R ¹ and R ² are each independently a hydrogen atom or a hydrocarbon group, and X represents a divalent hydrocarbon group forming a ring together with the --O--Si--O-- bond. However, the hydrogen atom of the carbon of X may be substituted with a halogen atom.)

[2] The non-aqueous electrolytic solution according to [1], wherein X in the general formula (1) has 2 or 3 carbon atoms forming a ring together with the -O-Si-O- bond.

[3] The total content of the compound represented by the general formula (1) is 0.001% by mass or more and 30% by mass or less with respect to the total amount of the non-aqueous electrolytic solution [1] or [2] The non-aqueous electrolytic solution described in .

[4] A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of [1] to [3]. A non-aqueous electrolyte battery.

[5] The non-aqueous electrolyte battery according to [4], wherein the negative electrode contains a negative electrode active material, and the negative electrode active material contains metal Si or Si oxide.

[6] The non-aqueous electrolyte battery according to [4] or [5], wherein the positive electrode contains a positive electrode active material, and the positive electrode active material is a metal oxide represented by the following compositional formula (2).

Li _a1 Ni _b1 Co _c1 M _d1 O ₂ (2)
(In the above formula (2), a1, b1, c1 and d1 are 0.90 ≤ a1 ≤ 1.10, 0.40 ≤ b1 ≤ 0.98, 0.01 ≤ c1 < 0.50, 0.01 ≤ d1 < 0.50 and satisfies b1 + c1 + d1 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er.)

ADVANTAGE OF THE INVENTION According to this invention, the nonaqueous electrolyte solution and battery which are excellent in the capacity|capacitance retention rate at the time of repeated charging/discharging can be provided. In addition, it is possible to provide a non-aqueous electrolytic solution and a battery that are excellent in suppressing the amount of gas generated during high-temperature storage.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail. However, the description given below is an example of the embodiment of the present invention, and the present invention is not limited to these contents. In addition, the present invention can be arbitrarily changed and implemented without departing from the gist thereof.

[1. Non-aqueous electrolyte]
[1-1. Compound represented by general formula (1)]
A non-aqueous electrolytic solution according to an embodiment of the present invention contains a compound represented by general formula (1). The non-aqueous electrolytic solution according to the embodiment of the present invention preferably contains an electrolyte and a non-aqueous solvent for dissolving the same, as in general non-aqueous electrolytic solutions.

（一般式（１）中、Ｒ^１及びＲ^２はそれぞれ独立に水素原子または炭化水素基であり、Ｘは－Ｏ－Ｓｉ－Ｏ－結合とともに環を構成する２価の炭化水素基を表す。ただし、Ｘの炭素が有する水素原子はハロゲン原子で置換されていてもよい。）

(In general formula (1), R ¹ and R ² are each independently a hydrogen atom or a hydrocarbon group, and X represents a divalent hydrocarbon group forming a ring together with the --O--Si--O-- bond. However, the hydrogen atom of the carbon of X may be substituted with a halogen atom.)

( ^R1 )
In general formula (1), R ¹ represents a hydrogen atom or a hydrocarbon group. From the viewpoint of suppressing the side reaction of the compound represented by the general formula (1) on the electrode, it is preferably a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 1-12, more preferably 1-6, and particularly preferably 1-4. With the above-described hydrocarbon group, the compound represented by the general formula (1) tends to localize near the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be further enhanced. Therefore, it is preferable.

Specific examples of hydrocarbon groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and aralkyl groups. Among them, an alkyl group, an alkenyl group, and an alkynyl group are preferable, and an alkyl group and an alkenyl group are particularly preferable, from the viewpoint of suppressing a side reaction of the compound represented by the general formula (1) on the electrode.

Alkyl groups include linear alkyl groups, branched alkyl groups and alkyl groups having a cyclic structure. Among them, the compound represented by the general formula (1) can suitably form an insulating film on the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be enhanced. It is preferably a group.

Specific examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n -nonyl group, n-decyl group, n-undecyl group, n-dodecyl group and other linear alkyl groups having 1 to 12 carbon atoms. Among them, straight-chain alkyl groups having 1 to 6 carbon atoms are preferred, and straight-chain alkyl groups having 1 to 4 carbon atoms are particularly preferred.

Specific examples of branched alkyl groups include methylethyl, methylpropyl, methylbutyl, methylpentyl, methylhexyl, methylheptyl, methyloctyl, methylnonyl, methyldecyl, and methylundecyl groups. ; dimethylethyl group (tert-butyl group), dimethylpropyl group, dimethylbutyl group, dimethylpentyl group, dimethylhexyl group, dimethylheptyl group, dimethyloctyl group; trimethylhexyl group, trimethylheptyl group; ethylpentyl group, ethylhexyl propylhexyl group, propylheptyl group; and butylhexyl group. Among them, branched alkyl groups having 1 to 6 carbon atoms such as methylethyl group, methylpropyl group, methylbutyl group, methylpentyl group, dimethylethyl group (tert-butyl group), dimethylpropyl group and dimethylbutyl group are preferable. Particularly preferred are branched alkyl groups having 1 to 4 carbon atoms such as methylethyl group, methylpropyl group and dimethylethyl group (tert-butyl group). In addition, in the examples of the branched alkyl group, the position of the branch is arbitrary.

Specific examples of alkyl groups having a cyclic structure include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclohexylmethyl, cyclohexylethyl, Examples thereof include alkyl groups having a cyclic structure having 3 to 12 carbon atoms such as methylcyclohexyl group, dimethylcyclohexyl group, ethylcyclohexyl group and methylcyclohexylmethyl group. Among them, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclocyclohexylmethyl, cyclohexylethyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl and methylcyclohexylmethyl Alkyl groups having a cyclic structure having 3 to 8 carbon atoms are preferred, and particularly preferred are cyclohexyl, cyclohexylmethyl, cyclohexylethyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl and methylcyclohexylmethyl groups. It is an alkyl group having a cyclic structure with 6 to 8 carbon atoms.

Among the alkyl groups mentioned above, those having 1 to 6 carbon atoms such as methyl group, ethyl group, n-propyl group, methylethyl group, n-butyl group, tert-butyl group, n-pentyl group and n-hexyl group Alkyl groups are preferred, and alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, methylethyl, n-butyl, and tert-butyl are more preferred, and methyl and ethyl are preferred. More preferably, a methyl group is particularly preferred. With these alkyl groups, the compound represented by the general formula (1) tends to be localized in the vicinity of the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be further enhanced. preferable.

Specific examples of alkenyl groups include vinyl groups, allyl groups, isopropenyl groups, methallyl groups, 2-butenyl groups, 3-methyl 2-butenyl groups, 3-butenyl groups, and 4-pentenyl groups having 2 carbon atoms. -12 alkenyl groups are included. Among them, preferred are alkenyl groups having 2 to 6 carbon atoms such as vinyl, allyl, methallyl and 2-butenyl groups, and more preferred are vinyl, allyl and methallyl groups having 2 carbon atoms. It is an alkenyl group of 1 to 4, more preferably a vinyl group or an allyl group, and most preferably a vinyl group. The above-mentioned alkenyl group is preferable because the compound represented by the general formula (1) can suitably form an insulating film on the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be enhanced. .

Specific examples of alkynyl groups include alkynyl groups having 2 to 12 carbon atoms such as ethynyl, 2-propynyl, 2-butynyl, 3-butynyl, 4-pentynyl, and 5-hexynyl groups. . Among them, preferred are alkynyl groups having 2 to 6 carbon atoms such as ethynyl, 2-propynyl, 2-butynyl and 3-butynyl, and particularly preferred are ethynyl and 2-propynyl. . The above-mentioned alkynyl group is preferable because the compound represented by the general formula (1) can suitably form an insulating film on the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be enhanced. .

Specific examples of aryl groups include aryl groups having 6 to 12 carbon atoms such as phenyl, tolyl, and mesityl. Among them, the compound represented by the general formula (1) tends to be localized in the vicinity of the surface of the positive electrode active material and/or the negative electrode active material, and from the viewpoint that the effect can be further enhanced, a phenyl group, and an aryl group having 6 to 7 carbon atoms such as a tolyl group is preferred, and a phenyl group is particularly preferred.

The aralkyl group includes aralkyl groups having 7 to 12 carbon atoms such as phenylmethyl group (benzyl group), phenylethyl group (phenethyl group), phenylpropyl group and phenylbutyl group. Among them, the compound represented by the general formula (1) tends to be localized in the vicinity of the surface of the positive electrode active material and/or the negative electrode active material, and from the viewpoint that the effect can be further enhanced, a benzyl group and An aralkyl group having 7 to 8 carbon atoms such as a phenethyl group is preferred, and a benzyl group is particularly preferred.

Among the above hydrocarbon groups, alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, methylethyl group, n-butyl group and tert-butyl group, vinyl group, allyl group, Alkenyl groups having 2 to 4 carbon atoms such as methallyl group and 2-butenyl group are preferred, among them, methyl group, ethyl group and vinyl group are more preferred, and methyl group and vinyl group are particularly preferred. With the above hydrocarbon group, the compound represented by the general formula (1) can suitably form an insulating film on the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be enhanced. preferable.

( ^R2 )
In general formula (1), ^R2 represents a hydrogen atom or a hydrocarbon group. From the viewpoint of suppressing the side reaction of the compound represented by the general formula (1) on the electrode, R ² is preferably a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 1-12, more preferably 1-6, and particularly preferably 1-4. With the above-described hydrocarbon group, the compound represented by the general formula (1) tends to localize near the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be further enhanced. Therefore, it is preferable. R ¹ and R ² may be the same or different.

Specific examples of hydrocarbon groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and aralkyl groups. Among them, alkyl groups, alkenyl groups, and alkynyl groups are preferable, alkyl groups and alkenyl groups are more preferable, and alkyl groups are particularly preferable, from the viewpoint of suppressing side reactions of the compound represented by the general formula (1) on the electrode.

Specific examples and preferred examples of the alkyl group, alkenyl group, alkynyl group, aryl group and aralkyl group are the same as those shown for R ¹ .

Among the above hydrocarbon groups, C 1-6 groups such as methyl group, ethyl group, n-propyl group, methylethyl group, n-butyl group, tert-butyl group, n-pentyl group and n-hexyl group An alkyl group of is preferred, more preferably an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, a methylethyl group, an n-butyl group, and a tert-butyl group, a methyl group and an ethyl group is more preferred, and a methyl group is particularly preferred. With these hydrocarbon groups, the compound represented by the general formula (1) tends to localize near the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be further enhanced. Therefore, it is preferable.

(X)
In general formula (1), X represents a divalent hydrocarbon group forming a ring together with an --O--Si--O-- bond. The number of carbon atoms in the hydrocarbon group is preferably 1-10, more preferably 2-6. With the above-described hydrocarbon group, the compound represented by the general formula (1) tends to localize near the surface of the positive electrode active material and/or the negative electrode active material, and the effect can be further enhanced. Therefore, it is preferable. At least one of the hydrogen atoms of the carbon atoms of X may be substituted with a halogen atom. Specific examples of the halogen atom include fluorine atom, chlorine atom, bromine atom and iodine atom, preferably fluorine atom. In X, the number of carbon atoms forming a ring together with the --O--Si--O-- bond is preferably 2 or 3, particularly preferably 3.

Specific examples of the divalent hydrocarbon group include divalent hydrocarbon groups such as an alkylene group, an alkenylene group, and an alkynylene group, and divalent hydrocarbon groups in which at least one of the hydrogen atoms of these hydrocarbon groups is substituted with a halogen atom. is preferably a divalent hydrocarbon group such as an alkylene group, an alkenylene group, or an alkynylene group. The compounds described above are preferable because the compound represented by the general formula (1) can form an insulating film on the surface of the positive electrode active material and/or the negative electrode active material, and can enhance the effect thereof.

The alkylene group specifically includes a linear alkylene group, a branched alkylene group, and an alkylene group having a cyclic structure.

Specific examples of linear alkylene groups include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene and decylene groups.

Specific examples of branched alkylene groups include a methylethylene group, a methylpropylene group, a methylbutylene group, a methylpentylene group, a methylhexylene group, a methylheptylene group, a methyloctylene group, a methylnonylene group; a dimethylethylene group, a dimethyl Propylene group, dimethylbutylene group, dimethylpentylene group, dimethylhexylene group, dimethylheptylene group, dimethyloctylene group; trimethylethylene group, trimethylpropylene group, trimethylbutylene group, trimethylpentylene group, trimethylhexylene group, trimethyl heptylene group; tetramethylethylene group, tetramethylpropylene group, tetramethylbutylene group, tetramethylpentylene group, tetramethylhexylene group and the like. In addition, in the examples of the branched alkyl group, the position of the branch is arbitrary.

Specific examples of the alkylene group having a cyclic structure include cyclopentylene, cyclohexylene, ethylene, propylene, and other straight-chain alkylene groups having carbon atoms as constituents, and alkylene groups containing cyclic structures. An alkylene group containing a cyclic structure having a carbon-carbon bond of a linear alkylene group such as an ethylene group or a propylene group as a constituent, and the like.

Specific examples of alkenylene groups include vinylene, propenylene, 1-butenylene, 2-butenylene, butadienylene, pentenylene, hexenylene, heptenylene, and octenylene groups.

Among the above hydrocarbon groups, -O-Si-O such as ethylene group, propylene group, methylethylene group, methylpropylene group, dimethylethylene group, dimethylpropylene group, trimethylethylene group, trimethylpropylene group, tetramethylethylene group, etc. - An alkylene group having 2 or 3 carbon atoms forming a ring together with a bond is preferable, and forms a ring together with a -O-Si-O- bond such as a propylene group, a methylpropylene group, a dimethylpropylene group, a trimethylpropylene group, etc. An alkylene group having 3 carbon atoms and the like are more preferable. In the above-described alkylene group, the ring structure containing the -O-Si-O- bond forms a 5-membered ring or a 6-membered ring (particularly preferably a 6-membered ring), and the positive electrode active material and / or the negative electrode active material The compound represented by the general formula (1) can suitably form an insulating film on the surface of (1), and can enhance its action and effect. In addition, among the hydrocarbon groups, a straight-chain alkylene group is preferable from the viewpoint of further suppressing gas during high-temperature storage when a battery is produced using the present electrolytic solution and a specific positive electrode material.

From the viewpoint of suppressing the side reaction on the electrode of the compound represented by the general formula (1), it is also preferable that at least one of the hydrogen atoms of the above-described alkylene group is substituted with a fluorine atom. Incidentally, the substitution position of the fluorine atom is arbitrary. Specific examples of the alkylene group substituted with a fluorine atom include a fluoroethylene group, a trifluoromethylethylene group, a 1,2-bis(trifluoromethyl)ethylene group, 1,1,2,2-tetrakis(trifluoromethyl ) ethylene group, 2-fluoropropylene group, 2,2-difluoropropylene group, 1-trifluoromethylpropylene group, 1,3-bis(trifluoromethyl)propylene group and the like.

(combination of R ¹ , R ² and X)
Among the compounds represented by the general formula (1), as the combination of R ¹ , R ² and X, R ¹ is an alkyl group or an alkenyl group, R ² is an alkyl group, and X is an alkylene group. It is particularly preferred that R ¹ is a methyl group or a vinyl group, R ² is a methyl group, and X is a propylene group, a methylpropylene group or a dimethylpropylene group. Due to the above combination, the effect of improving the capacity retention rate during repeated charging and discharging when a non-aqueous electrolyte secondary battery is formed is large.

From the viewpoint of suppressing gas during high-temperature storage when the present electrolyte solution and a specific positive electrode material are used to form a battery, R ¹ is an alkenyl group, R ² is an alkyl group, and X is an alkylene group. Compounds are preferred, particularly preferred are compounds in which R ¹ is a vinyl group, R ² is a methyl group and X is a propylene, methylpropylene or dimethylpropylene group.

(Examples of compounds represented by general formula (1))
Specific examples of the compound represented by the general formula (1) are shown below. The compound represented by general formula (1) according to the present embodiment is not limited to the compounds represented by formulas (B1-1) to (B1-195) exemplified below. .

Among the above compounds, compounds in which X has 2 or 3 carbon atoms forming a ring together with the -O-Si-O- bond (B-1 to B-50, B-54 to B-110, B-114 to B-170, B-174 to B-195) are preferred, R ¹ is an alkyl group or an alkenyl group, R ² is an alkyl group, and X is a carbon that forms a ring together with the —O—Si—O— bond. Compounds with a number of 2 or 3 (B-1 to B-50, B-54 to B-110, B-114 to B-120, B-181 to B-186, B-194) are more preferred, and R A compound (B ^{- 1} ~ B-19, B-40 ~ B-46, B-49 ~ B-50, B-61 ~ B-79, B-100 ~ B-106, B-109 ~ B-110, B-181 ~ B -186, B-194) ^are more preferred, and compounds (B- ¹ to B-7, B-61 to B-67) are particularly preferred. By being the above compound, the effect of improving the capacity retention rate during repeated charging and discharging when a non-aqueous electrolyte secondary battery is formed is large.

Furthermore, from the viewpoint of suppressing gas during high-temperature storage when a battery is made using the present electrolytic solution and a specific positive electrode material, R ¹ is an alkenyl group, R ² is an alkyl group, and X is —O Compounds (B-61 to B-79, B-100 to B-106, B-109 to B-110, B -181 to B-186) are preferred, and compounds (B-61 to B-67) in which R ¹ is a vinyl group, R ² is a methyl group, and X is a propylene group, a methylpropylene group, or a dimethylpropylene group is particularly preferred.

The compounds represented by the general formula (1) used in the embodiment of the present invention may be used singly, or two or more may be used in any combination and ratio. In addition, the content of the compound represented by the general formula (1) is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the present invention, but the content of the compound represented by the general formula (1) The total is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more, relative to the total amount of the non-aqueous electrolytic solution. , is particularly preferably 0.05% by mass or more, and most preferably 0.1% by mass or more. Within the above range, a suitable film is formed on the surface of the positive electrode active material and/or the negative electrode active material, and the effect of suppressing side reactions of constituent components of the electrolytic solution is exhibited.

On the other hand, the total content of the compounds represented by the general formula (1) is preferably 30% by mass or less, more preferably 10% by mass or less, relative to the total amount of the non-aqueous electrolytic solution. , more preferably 5% by mass or less, more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1% by mass or less. Within the above range, the negative electrode film is not excessively formed, and the permeability of lithium ions can be ensured, so that the input/output characteristics and the charge/discharge rate characteristics are within a suitable range.

The method for producing the compound represented by formula (1) is not particularly limited, and it can be produced by combining known methods. For example, a method of reacting a dihalogenated silane and a dihydric alcohol, and a method of reacting a dialkoxysilane and a dihydric alcohol, and the like can be mentioned.

Preparation of the non-aqueous electrolytic solution containing the compound represented by the general formula (1) may be performed by a known method, and is not particularly limited. For example, a method of adding a separately synthesized compound represented by (1) to a non-aqueous electrolytic solution, or a method of adding a separately synthesized compound represented by general formula (1) into a solvent and then dissolving the electrolyte salt. A method of using a non-aqueous electrolytic solution, a battery element (battery element) is constructed by mixing a compound represented by the general formula (1) into a battery component such as an active material, an electrode plate, a separator, etc., which will be described later, A method of dissolving a compound represented by the general formula (1) in a non-aqueous electrolyte when assembling an energy device such as a non-aqueous electrolyte secondary battery by injecting a non-aqueous electrolyte, a non-aqueous electrolyte or a non-aqueous electrolyte In the aqueous electrolyte secondary battery, a compound capable of generating the compound represented by general formula (1) is mixed in advance in the non-aqueous electrolyte or in the non-aqueous electrolyte secondary battery, and the general formula (1) and a method for obtaining an electrolytic solution containing a compound represented by the above. Either method may be used in the present invention.

In addition, the method for measuring the content of the compound represented by the general formula (1) in the non-aqueous electrolyte and the non-aqueous electrolyte secondary battery is not particularly limited, and is a known method. It can be used arbitrarily. Specific examples include gas chromatography, liquid chromatography, ¹ H and ¹³ C nuclear magnetic resonance spectroscopy (hereinafter sometimes referred to as “NMR”), and the like.

The reason why the effect of the present invention is obtained by the non-aqueous electrolyte solution containing the compound represented by the general formula (1) is presumed as follows. Since the compound represented by the general formula (1) has a Si—O bond, which is a reactive site, it reacts with the negative electrode active material to suitably modify the surface of the negative electrode, thereby suppressing deterioration of the negative electrode active material. , is considered to contribute to the improvement of the capacity retention rate during repeated charging and discharging. Furthermore, since the compound represented by the general formula (1) has a structure in which —O—Si—O— bonding sites are linked by hydrocarbon groups, it reacts on the electrode surface to form an intermolecular crosslinked body. , is thought to act as a coating that protects the electrode surface. Excessive solvent decomposition is suppressed by this protective coating, which is thought to contribute to improvement of the capacity retention rate during repeated charging and discharging and suppression of gas generation due to solvent decomposition. A compound having three or more Si—O bonds in the ring structure, such as hexamethylcyclotrisiloxane, has low durability of the intermolecular crosslinked body, so that the effect of improving the capacity retention rate during repeated charging and discharging can be obtained. do not have. Further, if the compound has two or more cyclic structures (one cyclic structure included in the general formula (1)) composed of —O—Si—O— bonds and divalent hydrocarbon groups, the electrode Since a relatively large amount of intermolecular crosslinks tends to be formed on the surface, the effect of improving the capacity retention rate during repeated charging and discharging cannot be expected as much as in the case of using the compound represented by the general formula (1). When the compound represented by the general formula (1) is used, an intermolecular crosslinked body is formed in which the durability and amount of the molecular ring crosslinked body are suitably controlled, and the capacity retention rate during repeated charging and discharging is remarkable. I think it will improve to

The compound represented by general formula (1) has a silicon-carbon bonding site and a silicon-oxygen bonding site in the molecule. Since the electronegativity of silicon atoms is lower than that of carbon atoms and oxygen atoms, the polarities of silicon-carbon bonds and silicon-oxygen bonds are biased. It is believed that the electron-dense sites interact with specific electron-deficient sites on the surface of the positive electrode to stabilize the surface of the positive electrode, thereby suppressing gas from the positive electrode. Among the compounds represented by the general formula (1), compounds in which R ¹ is a hydrocarbon group having a carbon-carbon unsaturated bond such as an alkenyl group are excellent because they can more preferably act on the surface of the positive electrode. It is estimated that a gas suppression effect can be obtained.

[1-2. Electrolytes]
<Lithium salt>
A lithium salt is usually used as the electrolyte in the non-aqueous electrolytic solution. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used. Specific examples include the following.

Examples include lithium fluoroborate, lithium fluorophosphate, lithium tungstate, lithium carboxylate, lithium sulfonate, lithium imide, lithium methide, lithium oxalate, and fluorine-containing organic lithium salts. .

LiPF ₆ , Li ₂ PO ₃ F and LiPO ₂ F ₂ as lithium fluorophosphate salts; LiFSO ₃ and CH ₃ SO ₃ Li as lithium sulfonate salts; _LiN ( FSO ₂ ) ₂ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, Lithium cyclic 1,3-perfluoropropanedisulfonylimide; as lithium methide salts, LiC(FSO ₂ ) ₃ , LiC(CF ₃ SO ₂ ) ₃ , LiC(C ₂ F ₅ SO ₂ ) ₃ ; as lithium oxalate salts, Lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, lithium tris(oxalato)phosphate, etc. It is more preferable from the viewpoint of improving properties, high-temperature storage properties, cycle properties, and the like. More preferred are LiPF ₆ , LiN(FSO ₂ ) ₂ , lithium bis(oxalato)borate and LiFSO ₃ , and LiPF ₆ is particularly preferred. Moreover, the said electrolyte salt may be used independently, or may use 2 or more types together.

The combination of two or more electrolyte salts is not particularly limited, but LiPF ₆ and LiN(FSO ₂ ) ₂ ; LiPF ₆ and LiBF ₄ ; LiPF ₆ and LiN(CF ₃ SO ₂ ) ₂ ; LiBF ₄ and LiN ( FSO ₂ ) ₂ ; LiBF ₄ and LiPF ₆ and LiN(FSO ₂ ) ₂ . Among them, LiPF ₆ and LiN(FSO ₂ ) ₂ ; LiPF ₆ and LiBF ₄ ; LiBF ₄ , LiPF ₆ and LiN(FSO ₂ ) ₂ are preferred.
The content of the electrolyte in the non-aqueous electrolyte (the total content in the case of two or more types) is not particularly limited, but is usually 8% by mass or more, preferably 8.5%, based on the total amount of the non-aqueous electrolyte. % by mass or more, more preferably 9% by mass or more, and usually 18% by mass or less, preferably 17% by mass or less, more preferably 16% by mass or less. When the content of the electrolyte is within the above range, the electrical conductivity is appropriate for battery operation, and there is a tendency to obtain sufficient output characteristics.

[1-3. Non-aqueous solvent]
A non-aqueous electrolytic solution according to an embodiment of the invention normally contains, as its main component, a non-aqueous solvent that dissolves the above-described electrolyte, like a general non-aqueous electrolytic solution. The non-aqueous solvent to be used is not particularly limited as long as it dissolves the electrolyte described above, and known organic solvents can be used. Examples of organic solvents include, but are not limited to, saturated cyclic carbonates, chain carbonates, chain carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds. An organic solvent can be used individually by 1 type or in combination of 2 or more types.

The combination of two or more organic solvents is not particularly limited, but saturated cyclic carbonate and chain carbonate, saturated cyclic carbonate and chain carboxylic acid ester, cyclic carboxylic acid ester and chain carbonate, saturated cyclic carbonate, chain linear carbonates and chain carboxylic acid esters. Of these, saturated cyclic carbonates and chain carbonates, and saturated cyclic carbonates, chain carbonates and chain carboxylic acid esters are preferred.

[1-3-1. saturated cyclic carbonate]
Examples of saturated cyclic carbonates include those having an alkylene group having 2 to 4 carbon atoms, and saturated cyclic carbonates having 2 to 3 carbon atoms are preferably used from the viewpoint of improving battery characteristics resulting from an improvement in the degree of dissociation of lithium ions. be done.

Specific examples of saturated cyclic carbonates include ethylene carbonate, propylene carbonate, and butylene carbonate. Among them, ethylene carbonate or propylene carbonate is preferable, and ethylene carbonate which is difficult to be oxidized/reduced is more preferable. Saturated cyclic carbonates may be used alone, or two or more of them may be used in any combination and ratio.

The content of the saturated cyclic carbonate is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the invention according to the present embodiment. The content is preferably 5% by volume or more, and is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the content of the saturated cyclic carbonate within this range, it is possible to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte secondary battery. is within a good range, the oxidation/reduction resistance of the non-aqueous electrolytic solution is improved, and the stability to the negative electrode and the stability during high-temperature storage tend to be improved.

In addition, volume % in this embodiment means the volume at 25 degreeC and 1 atmospheric pressure.

[1-3-2. chain carbonate]
As the chain carbonate, for example, one having 3 to 7 carbon atoms is used, and a chain carbonate having 3 to 5 carbon atoms is preferably used in order to adjust the viscosity of the electrolytic solution within an appropriate range.

Specific examples of chain carbonates include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethylmethyl carbonate and methyl-n-propyl carbonate. Particularly preferred are dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

Chain carbonates having a fluorine atom (hereinafter sometimes abbreviated as “fluorinated chain carbonate”) can also be preferably used. The number of fluorine atoms in the fluorinated linear carbonate is not particularly limited as long as it is 1 or more, but it is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, the plurality of fluorine atoms may be bonded to the same carbon or to different carbons.

Fluorinated linear carbonates include fluorinated dimethyl carbonate derivatives such as fluoromethylmethyl carbonate; fluorinated ethylmethyl carbonate derivatives such as 2-fluoroethylmethyl carbonate; and fluorinated diethyl carbonates such as ethyl-(2-fluoroethyl) carbonate. derivatives; and the like.

A chain carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

Although the content of the chain carbonate is not particularly limited, it is usually 15% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more, relative to the total amount of the non-aqueous solvent in the non-aqueous electrolyte, Also, it is usually 90% by volume or less, preferably 85% by volume or less, more preferably 80% by volume or less. By setting the content of the chain carbonate in the above range, the viscosity of the non-aqueous electrolyte is set in an appropriate range, the decrease in ionic conductivity is suppressed, and the output characteristics of the non-aqueous electrolyte secondary battery are kept in a good range. It becomes easier to

Furthermore, by combining a specific linear carbonate with a specific content of ethylene carbonate, the battery performance can be significantly improved.

For example, when dimethyl carbonate and ethyl methyl carbonate are selected as specific chain carbonates, the content of ethylene carbonate is not particularly limited, and is arbitrary as long as the effects of the invention according to the present embodiment are not significantly impaired. It is usually 15% by volume or more, preferably 20% by volume or more, and usually 45% by volume or less, preferably 40% by volume or less, based on the total amount of the non-aqueous solvent in the aqueous electrolyte. It is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less, relative to the total amount of the non-aqueous solvent in the aqueous electrolyte, and the content of ethyl methyl carbonate is It is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less, relative to the total amount of the nonaqueous solvent in the nonaqueous electrolytic solution. By setting the content within the above range, there is a tendency that high-temperature stability is excellent and gas generation is suppressed.
In addition, when ethylmethyl carbonate and diethyl carbonate are selected as the specific chain carbonate, the content of ethylene carbonate is not particularly limited, and is arbitrary as long as the effects of the invention according to the present embodiment are not significantly impaired. It is usually 15% by volume or more, preferably 20% by volume or more, and usually 45% by volume or less, preferably 40% by volume or less, relative to the total amount of the non-aqueous solvent in the aqueous electrolyte, and the content of ethyl methyl carbonate is It is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less, relative to the total amount of the non-aqueous solvent in the non-aqueous electrolyte. It is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less, relative to the total amount of the nonaqueous solvent in the nonaqueous electrolytic solution. By setting the content within the above range, there is a tendency that high-temperature stability is excellent and gas generation is suppressed.

[1-3-3. Chain carboxylic acid ester]
Examples of chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, and isobutyric acid. Ethyl, and methyl pivalate. Among them, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate are preferable from the viewpoint of improving battery characteristics. Chain carboxylic acid esters (eg, methyl trifluoroacetate, ethyl trifluoroacetate, etc.) obtained by substituting a portion of the hydrogen atoms of the above compounds with fluorine are also suitable for use.

The content of the chain carboxylic acid ester is generally 1% by volume or more, preferably 5% by volume or more, more preferably 15% by volume or more, relative to the total amount of the non-aqueous solvent in the non-aqueous electrolytic solution. Within this range, the electrical conductivity of the non-aqueous electrolytic solution is improved, and the large current discharge characteristics of the non-aqueous electrolytic solution battery are easily improved. Moreover, the content of the chain carboxylic acid ester is usually 70% by volume or less, preferably 50% by volume or less, and more preferably 40% by volume or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution can be adjusted to an appropriate range, a decrease in electrical conductivity can be avoided, an increase in negative electrode resistance can be suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery can be achieved. It becomes easier to bring the characteristics into a favorable range.

[1-3-4. Cyclic carboxylic acid ester]
Cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone. Among these, γ-butyrolactone is more preferred. A cyclic carboxylic acid ester obtained by substituting a portion of the hydrogen atoms of the above compounds with fluorine is also suitable for use.

The content of the cyclic carboxylic acid ester is generally 1% by volume or more, preferably 5% by volume or more, more preferably 15% by volume or more, relative to the total amount of the non-aqueous solvent in the non-aqueous electrolytic solution. Within this range, the electrical conductivity of the non-aqueous electrolytic solution is improved, and the large current discharge characteristics of the non-aqueous electrolytic solution secondary battery are easily improved. Moreover, the content of the cyclic carboxylic acid ester is usually 70% by volume or less, preferably 50% by volume or less, and more preferably 40% by volume or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution can be adjusted to an appropriate range, a decrease in electrical conductivity can be avoided, an increase in negative electrode resistance can be suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery can be achieved. It becomes easier to bring the characteristics into a favorable range.

[1-3-5. Ether-based compound]
Ether-based compounds include chain ethers having 3 to 10 carbon atoms such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and tetrahydrofuran. , 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane and other cyclic compounds having 3 to 6 carbon atoms Ethers are preferred. A portion of the hydrogen atoms in the above ether-based compound may be substituted with fluorine.

Among them, as chain ethers having 3 to 10 carbon atoms, dimethoxymethane, diethoxy Methane and ethoxymethoxymethane are preferred, and cyclic ethers having 3 to 6 carbon atoms are preferably tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, etc., since they give high ion conductivity.

The content of the ether-based compound is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the invention according to the present embodiment. It is preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less. When the content of the ether-based compound is within the above range, it is easy to secure the effect of improving the degree of dissociation of lithium ions by the ether-based compound and the effect of improving the ionic conductivity derived from the viscosity reduction of the non-aqueous electrolytic solution. In addition, when the negative electrode active material is a carbonaceous material, the phenomenon of co-insertion of the chain ether together with the lithium ions can be suppressed, so that the input/output characteristics and charge/discharge rate characteristics can be set within appropriate ranges.

[1-3-6. Sulfone compound]
The sulfone-based compound is not particularly limited, and may be a cyclic sulfone or a chain sulfone. Cyclic sulfones generally have 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms, and chain sulfones generally have 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms. Although the number of sulfonyl groups in one molecule of the sulfone compound is not particularly limited, it is usually one or two.

Cyclic sulfones include trimethylenesulfones, tetramethylenesulfones, hexamethylenesulfones, etc., which are monosulfone compounds; and trimethylenedisulfones, tetramethylenedisulfones, hexamethylenedisulfones, etc., which are disulfone compounds. Among them, tetramethylenesulfones, tetramethylenedisulfones, hexamethylenesulfones, and hexamethylenedisulfones are more preferable, and tetramethylenesulfones (sulfolanes) are particularly preferable from the viewpoint of dielectric constant and viscosity.

As sulfolanes, sulfolane and sulfolane derivatives are preferred. As the sulfolane derivative, one in which one or more of the hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring is substituted with a fluorine atom, an alkyl group or a fluorine-substituted alkyl group is preferred.

Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane and the like have high ionic conductivity. It is preferable in terms of high input/output.

Chain sulfones include dimethylsulfone, ethylmethylsulfone, diethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, pentafluoroethylmethylsulfone and the like. Among these, dimethylsulfone, ethylmethylsulfone, and monofluoromethylmethylsulfone are preferable because they improve the high-temperature storage stability of the electrolytic solution.

The content of the sulfone-based compound is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the invention according to the present embodiment. Above, it is preferably 0.5% by volume or more, more preferably 1% by volume or more, and is usually 40% by volume or less, preferably 35% by volume or less, more preferably 30% by volume or less. If the content of the sulfone-based compound is within the above range, there is a tendency to obtain an electrolytic solution with excellent high-temperature storage stability.

[1-4. Auxiliary agent]
The non-aqueous electrolytic solution of the present invention may contain various auxiliary agents as long as they do not significantly impair the effects of the present invention. As the auxiliary agent, any conventionally known one can be used. In addition, an auxiliary agent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

Examples of auxiliary agents that may be contained in the non-aqueous electrolytic solution include cyclic carbonates having a carbon-carbon unsaturated bond, fluorine-containing cyclic carbonates, organic compounds having an isocyanate group, organic compounds having an isocyanuric acid skeleton, phosphorus-containing organic compounds, sulfur-containing organic compounds, fluorine-free carboxylic acid esters, cyano group-containing organic compounds, silicon-containing compounds, acid anhydrides, aromatic compounds, triple bond-containing compounds, ether bond-containing cyclic compounds, phosphazene compounds, oxalic acid Salts, phosphates having P═O bond and PF bond, salts having FSO ₂ skeleton, alkyl sulfates and the like can be exemplified. Examples thereof include compounds described in International Publication No. 2015/111676. A cyclic compound having an ether bond can be used as an auxiliary agent in a non-aqueous electrolytic solution, and includes those that can also be used as a non-aqueous solvent as shown in "1-3. Non-aqueous solvent". When a cyclic compound having an ether bond is used as an auxiliary agent, it is used in an amount of less than 4% by mass. Borate, oxalate, phosphate with P=O bond and PF bond, salt with _FSO2 skeleton, and alkyl sulfate can also be used as auxiliaries in the non-aqueous electrolyte, As shown in "1-2. Electrolyte", those that can be used as electrolytes are also included. When these compounds are used as auxiliaries, they are used at less than 3% by mass.

(Auxiliary content)
Auxiliaries may be used singly or in combination of two or more in any desired ratio. When the non-aqueous electrolytic solution contains an auxiliary agent, the content of the auxiliary agent (the total amount in the case of two or more types) is usually 1.0 × 10 ^-3 mass% or more with respect to the total amount of the non-aqueous electrolytic solution. , preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less. If the content of the auxiliary agent is within this range, the battery characteristics, particularly the durability characteristics, can be remarkably improved. Although the principle of this effect is not clear, it is thought that the side reaction of the electrolytic solution components on the electrode can be minimized by containing the auxiliary agent at this ratio.

(Mass ratio of electrolyte and auxiliary agent: auxiliary agent/LiPF ₆ )
When the non-aqueous electrolyte contains an auxiliary agent and LiPF ₆ , the mass ratio of the content of the auxiliary agent (the total amount when two or more types are used) to the content of LiPF ₆ (auxiliary [g]/LiPF ₆ [ g]) is usually 0.00005 or more, preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, most preferably 0.05 or more, Usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, still more preferably 0.35 or less, still more preferably 0.30 or less, even more preferably 0.25 or less, particularly preferably 0.20 or less, most preferably 0.15 or less. When the mass ratio is within this range, battery characteristics, particularly durability characteristics, can be remarkably improved. Although the principle of this effect is not clear, it is believed that the content of the auxiliary agent and LiPF ₆ in this ratio minimizes the decomposition side reaction of LiPF ₆ in the battery system.

Among them, a cyclic carbonate having a carbon-carbon unsaturated bond, a fluorine-containing cyclic carbonate, an organic compound having an isocyanate group, an organic compound having an isocyanuric acid skeleton, a sulfur-containing organic compound, a fluorine-free carboxylic acid ester, and a cyano group Preferred are organic compounds, silicon-containing compounds, acid anhydrides, oxalates, phosphates having P═O and PF bonds, salts having an FSO ₂ skeleton, and alkyl sulfates.

In addition, the use of one or more selected from cyclic carbonates having a carbon-carbon unsaturated bond and fluorine-containing cyclic carbonates is preferable in that the durability of the negative electrode coating can be increased and the cycle characteristics can be improved.

The total content of compounds selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond and a fluorine-containing cyclic carbonate is usually 0 in 100% by mass of the non-aqueous electrolyte (with respect to the total amount of the non-aqueous electrolyte). 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and usually 10% by mass or less , preferably 8% by mass or less, more preferably 5% by mass or less. When two or more are used in combination, the total content preferably satisfies the above range.

In addition, the non-aqueous electrolytic solution may contain, as an auxiliary agent, a phosphate having a P=O bond and a PF bond, a salt having an _FSO2 skeleton, an alkyl sulfate, or an oxalate. Phosphates having P═O bonds and PF bonds, salts having an FSO ₂ skeleton, alkyl sulfates, and oxalates, from the viewpoint of suitably forming a composite film with the compound represented by formula (1) It preferably contains one or more compounds selected from the group consisting of, and more preferably contains a phosphate having a P═O bond and a PF bond and/or a salt having an FSO ₂ skeleton.

The total content of compounds selected from the group consisting of phosphates having P=O bonds and PF bonds, salts having an FSO ₂ skeleton, alkyl sulfates, and oxalates is 100% by mass of the non-aqueous electrolytic solution. Medium (relative to the total amount of the non-aqueous electrolytic solution) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0.2% by mass % by mass or more, and usually 10% by mass or less, preferably 8% by mass or less, and more preferably 5% by mass or less. When two or more are used in combination, the total content preferably satisfies the above range.

Below, cyclic carbonates having carbon-carbon unsaturated bonds, fluorine-containing cyclic carbonates, phosphates having P=O bonds and PF bonds, salts having an _FSO2 skeleton, alkyl sulfates and oxalates are described in detail. describe.

(Cyclic carbonate having a carbon-carbon unsaturated bond)
The cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter also referred to as "unsaturated cyclic carbonate") is not particularly limited as long as it has a carbon-carbon double bond or a carbon-carbon triple bond. In this specification, cyclic carbonates having an aromatic ring are also included in unsaturated cyclic carbonates.

Examples of unsaturated cyclic carbonates include vinylene carbonates such as vinylene carbonate and vinyl vinylene carbonate; aromatic rings such as vinylethylene carbonate, ethynylethylene carbonate and phenylethylene carbonate, or substituted compounds having a carbon-carbon double bond or carbon-carbon triple bond; ethylene carbonates substituted with a group; and the like.

In particular, from the viewpoint of forming a stable interface protective film, vinylene carbonates are preferred, vinylene carbonate, vinylethylene carbonate and ethynylethylene carbonate are more preferred, vinylene carbonate and vinylethylene carbonate are still more preferred, and vinylene carbonate is particularly preferred.

(fluorine-containing cyclic carbonate)
The fluorine-containing cyclic carbonate is not particularly limited as long as it has a cyclic carbonate structure and contains a fluorine atom.

Examples of fluorine-containing cyclic carbonates include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. For example, fluorinated ethylene carbonate (hereinafter referred to as "fluorinated ethylene carbonate") ), and derivatives thereof. Derivatives of fluorinated ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among them, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferable.

Fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4, 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate and the like.

In particular, from the viewpoint of imparting high ionic conductivity to the electrolytic solution and forming a stable interface protective film, fluorinated ethylene carbonate having 1 to 8 fluorine atoms is preferable, such as monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-Difluoroethylene carbonate is more preferred, and monofluoroethylene carbonate is even more preferred.

(Phosphate with P=O bond and PF bond)
The phosphate having a P=O bond and a PF bond is not particularly limited as long as it has a P=O bond and a PF bond in the molecule.

Examples of counter cations of phosphates having a PF bond include alkali metals such as lithium, sodium and potassium, with lithium being preferred.

As a fluorophosphate having a P=O bond,
_{monofluorophosphates} such as _Li2PO3F ;
difluorophosphates such _{as LiPO2F2 , NaPO2F2} , _{KPO2F2 ;}
etc.

In particular, difluorophosphate is preferable, and lithium difluorophosphate is more preferable, from the viewpoint of suitably forming a composite film with the compound represented by the general formula (1).

A fluorophosphate may be used singly or two or more may be used in any combination and ratio. The content of the fluorophosphate (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, in 100% by mass of the non-aqueous electrolyte solution. It is preferably 0.1% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. If the content of the fluorophosphate is within this range, it is possible to suitably form a composite coating with the compound represented by the general formula (1) and to minimize side reactions of the additive on the electrode. can.

The mass ratio of the compound represented by the general formula (1) and the phosphate having a P=O bond and a PF bond (the total amount if two or more types) is represented by the general formula (1) Compound/Phosphate having P=O bond and PF bond having P=O bond, usually 1/100 or more, preferably 10/100 or more, more preferably 20/100 or more, still more preferably It is 25/100 or more, usually 10000/100 or less, preferably 500/100 or less, more preferably 100/100, particularly preferably 80/100 or less, and most preferably 40/100 or less. When the mass ratio is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and side reactions of the additive on the electrode can be minimized.

When LiPF ₆ is contained in the non-aqueous electrolyte, the mass ratio of phosphate having P=O bond and PF bond (total amount if two or more types) to LiPF ₆ content (fluorophosphoric acid salt/LiPF ₆ ) is usually 0.00005 or more, preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, usually 1.0 or less, It is preferably 0.5 or less, more preferably 0.4 or less, and still more preferably 0.35 or less. If the mass ratio is within this range, the decomposition side reaction of LiPF ₆ in the non-aqueous electrolyte secondary battery can be minimized.

The content of phosphate having P=O bond and PF bond is determined by nuclear magnetic resonance (NMR) analysis. NMR analysis is usually performed, but ion chromatography (IC) analysis is also performed when it is difficult to assign other compounds due to solvent peaks.

(Salt with FSO ₂ backbone)
The salt having an _FSO2 skeleton used in this embodiment is not particularly limited as long as it has an _FSO2 skeleton in its molecule.

Counter cations of salts having an FSO ₂ skeleton include alkali metals such as lithium, sodium and potassium, among which lithium is preferred.

For example, fluorosulfones such as FSO ₃ Li, FSO ₃ Na, FSO ₃ K, FSO ₃ (CH ₃ ) ₄ N, FSO ₃ (C ₂ H ₅ ) ₄ N, FSO ₃ (nC ₄ H ₉ ) ₄ N acid salts;
fluorosulfonylimide salts such as LiN( _FSO2 ) ₂ , LiN( _FSO2 )( _{CF3SO2 )} ;
fluorosulfonylmethide salts such as LiC( _FSO2 ) ₃ ;
etc.

In particular, fluorosulfonate is preferable, and lithium fluorosulfonate is more preferable, from the viewpoint of suitably forming a composite film with the compound represented by the general formula (1).

Salts having an FSO ₂ skeleton may be used alone, or two or more of them may be used in any combination and ratio. The content of the salt having an FSO ₂ skeleton (the total amount in the case of two or more kinds) can be 0.001% by mass or more, preferably 0.01% by mass or more, in 100% by mass of the non-aqueous electrolyte. , more preferably 0.1% by mass or more, and may be 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. If the content of the salt having the FSO2 skeleton is within this range, the compound represented by the general formula (1) and the composite film are preferably formed to minimize side reactions of the additive on the electrode. can be done.

The mass ratio of the compound represented by the general formula (1) and the salt having the FSO ₂ skeleton (the total amount when two or more kinds are present) is the compound represented by the general formula (1)/the salt having the FSO ₂ skeleton is usually 1/100 or more, preferably 10/100 or more, more preferably 20/100 or more, still more preferably 25/100 or more, usually 10000/100 or less, preferably 500/100 or less, It is more preferably 100/100, particularly preferably 80/100 or less, and most preferably 40/100 or less. When the mass ratio is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and side reactions of the additive on the electrode can be minimized.

When LiPF ₆ is present in the non-aqueous electrolytic solution, the mass ratio (salt having FSO ₂ skeleton/LiPF ₆ ) of salt having FSO ₂ skeleton ₍ total amount if two or more kinds) to content of LiPF 6 is , usually 0.00005 or more, preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, usually 1.0 or less, preferably 0.5 or less , more preferably 0.4 or less, and still more preferably 0.35 or less. If the mass ratio is within this range, the decomposition side reaction of LiPF ₆ in the non-aqueous electrolyte secondary battery can be minimized.

The content of the salt having the FSO ₂ skeleton is determined by nuclear magnetic resonance (NMR) analysis. NMR analysis is usually performed, but ion chromatography (IC) analysis is also performed when it is difficult to assign other compounds due to solvent peaks.

(alkyl sulfate)
The alkyl sulfate used in the present embodiment is not particularly limited as long as it has an alkyl sulfate skeleton in the molecule.

Counter cations of alkyl sulfates include alkali metals such as lithium, sodium and potassium, with lithium being preferred.

Examples thereof include monoalkyl sulfates such as lithium methyl sulfate [LMS], lithium ethyl sulfate [LES], lithium 2,2,2-trifluoroethyl sulfate [LFES] and the like.

In particular, lithium methyl sulfate [LMS] and lithium ethyl sulfate [LES] are preferable, and lithium methyl sulfate [LMS] is more preferable, from the viewpoint of suitably forming a composite film with the compound represented by the general formula (1).

One alkyl sulfate may be used alone, or two or more thereof may be used in any combination and ratio. The content of the alkyl sulfate (total amount if two or more types) is 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.01% by mass or more in 100% by mass of the non-aqueous electrolytic solution. is 0.1% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. If the content of the alkylsulfate is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and side reactions of the additive on the electrode can be minimized.

The mass ratio of the compound represented by the general formula (1) and the alkyl sulfate (the total amount when two or more are used) is compound represented by the general formula (1)/alkyl sulfate, which is usually 1/100. or more, preferably 10/100 or more, more preferably 20/100 or more, still more preferably 25/100 or more, usually 10000/100 or less, preferably 500/100 or less, more preferably 100/100 , particularly preferably 80/100 or less, most preferably 40/100 or less. When the mass ratio is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and side reactions of the additive on the electrode can be minimized.

When LiPF ₆ is present in the non-aqueous electrolytic solution, the mass ratio (alkyl sulfate/LiPF ₆ ) of the alkyl sulfate (total amount if two or more kinds) _to the content of LiPF 6 is usually 0.00005 or more. , preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, usually 1.0 or less, preferably 0.5 or less, more preferably 0.025 or more. 4 or less, more preferably 0.35 or less. If the mass ratio is within this range, the decomposition side reaction of LiPF ₆ in the non-aqueous electrolyte secondary battery can be minimized.

The content of alkyl sulfate is determined by nuclear magnetic resonance (NMR) analysis. NMR analysis is usually performed, but ion chromatography (IC) analysis is also performed when it is difficult to assign other compounds due to solvent peaks.

(oxalate)
The oxalate is not particularly limited as long as it is a compound having at least one oxalic acid skeleton in the molecule.

Counter cations of oxalates include alkali metals such as lithium, sodium and potassium, with lithium being preferred.

oxalate borate salts such as lithium bis(oxalate) borate, lithium difluorooxalate borate;
oxalate phosphate salts such as lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, lithium tris(oxalate) phosphate;
etc.

In particular, oxalate borate salts are preferable, and lithium bis(oxalate)borate is more preferable, from the viewpoint of suitably forming a composite film with the compound represented by the general formula (1).

One type of oxalate may be used alone, or two or more types may be used together in any combination and ratio. The content of oxalate (the total amount when two or more types are used) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 100% by mass of the non-aqueous electrolytic solution. is 0.1% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. If the content of oxalate is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and the side reaction of the additive on the electrode can be minimized.

The mass ratio of the compound represented by the general formula (1) and the oxalate (the total amount in the case of two or more types) is usually 1/100, which is the compound represented by the general formula (1)/oxalate. or more, preferably 10/100 or more, more preferably 20/100 or more, still more preferably 25/100 or more, usually 10000/100 or less, preferably 500/100 or less, more preferably 100/100 , particularly preferably 80/100 or less, most preferably 40/100 or less. When the mass ratio is within this range, the compound represented by the general formula (1) and the composite film can be suitably formed, and side reactions of the additive on the electrode can be minimized.

When LiPF ₆ is contained in the non-aqueous electrolytic solution, the mass ratio (oxalate/LiPF ₆ ) of oxalate (total amount if two or more kinds) _to the content of LiPF 6 is usually 0.00005 or more. , preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, usually 1.0 or less, preferably 0.5 or less, more preferably 0.025 or more. 4 or less, more preferably 0.35 or less. If the mass ratio is within this range, the decomposition side reaction of LiPF ₆ in the non-aqueous electrolyte secondary battery can be minimized.

The oxalate content is determined by nuclear magnetic resonance (NMR) analysis. NMR analysis is usually performed, but ion chromatography (IC) analysis is also performed when it is difficult to assign other compounds due to solvent peaks.

[2. Non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery, which is one embodiment of the present invention, comprises a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, and a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions. A non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte.

[2-1. Non-aqueous electrolyte]
As the non-aqueous electrolytic solution, the non-aqueous electrolytic solution described above is used. It should be noted that other non-aqueous electrolytic solutions may be mixed with the above-described non-aqueous electrolytic solution without departing from the scope of the present invention.

[2-2. positive electrode]
The positive electrode is not particularly limited as long as it can occlude and release metal ions (for example, lithium ions). The positive electrode generally has a positive electrode active material on at least part of the current collector surface.

[2-2-1. Positive electrode active material]
The positive electrode active material is not particularly limited as long as it can occlude and release metal ions (for example, lithium ions), but lithium transition metal compounds are preferred. The positive electrode active material (lithium transition metal compound) used for the positive electrode is described below.

[2-2-1-1. Lithium transition metal compound]
A lithium transition metal compound is a compound having a structure capable of desorbing and inserting lithium ions. things, etc. Among them, phosphate compounds and lithium transition metal composite oxides are preferred, and lithium transition metal composite oxides are more preferred.

Lithium-transition metal composite oxides include those belonging to a spinel structure that enables three-dimensional diffusion and those that belong to a layered structure that enables two-dimensional diffusion of lithium ions.

Those having a spinel structure are generally represented by the following compositional formula (4).

_{Lix'M'2O4 ( 4} )
(In formula (4), x' is 1≤x'≤1.5, and M' represents at least one transition metal element.)

Specific examples include LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O ₄ and LiCoVO ₄ .

Those having a layered structure are generally represented by the following compositional formula (5).

Li _1+x MO ₂ (5)
(In formula (5), x is −0.1≦x≦0.5, and M represents at least one transition metal element.)

Specifically, LiCoO ₂ , LiNiO ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.80 Co _0.15 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _{0 .33O2 , Li1.05Ni0.33Co0.33Mn0.33O2 , LiNi0.5Co0.2Mn0.3O2 , Li1.05Ni0.5Co0 . _ _ _ _ _ _ 2Mn0.3O2 , LiNi0.6Co0.2Mn0.2O2 , LiNi0.8Co0.1Mn0.1O2 and the like . _ _}

Among them, from the viewpoint of improving the battery capacity, a lithium-transition metal composite oxide having a layered structure is preferable, and a transition metal composite oxide represented by the following compositional formula (6) is more preferable.

_{LiaNibMcO2 ( 6 )}
(In formula (6), a, b, and c are numerical values satisfying 0.90 ≤ a ≤ 1.10, 0.30 ≤ b ≤ 0.98, and 0.01 ≤ c ≤ 0.5. , b + c = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er.)

In particular, from the viewpoint of structural stability of the lithium-transition metal composite oxide, transition metal oxides represented by the following compositional formula (2) are preferred. In the transition metal compound represented by the compositional formula (2), the crystal structure is likely to be destabilized due to the high valence of Ni atoms. The compound represented by the general formula (1) has a polar silicon-carbon bonding site and a silicon-oxygen bonding site in the molecule. The electron-dense site of the compound represented by the general formula (1) interacts with the electron-deficient site of the transition metal compound represented by the compositional formula (2) to stabilize the surface of the positive electrode. It is believed that gas is suppressed. Among the compounds represented by the general formula (1), compounds in which R ¹ is a hydrocarbon group having a carbon-carbon unsaturated bond such as an alkenyl group are excellent because they can more preferably act on the surface of the positive electrode. It is estimated that a gas suppression effect can be obtained.

Li _a1 Ni _b1 Co _c1 M _d1 O ₂ (2)
(In formula (2), a1, b1, c1 and d1 are respectively 0.90 ≤ a1 ≤ 1.10, 0.40 ≤ b1 ≤ 0.98, 0.01 ≤ c1 < 0.50, 0.01 Shows a numerical value that satisfies ≤ d1 < 0.50 and satisfies b1 + c1 + d1 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er.)

In composition formula (2), the numerical value represented by a1 preferably satisfies 0.92≦a1≦1.08, and more preferably satisfies 0.95≦a1≦1.05. The numerical value represented by b1 preferably satisfies 0.45≦b1≦0.90, and more preferably satisfies 0.50≦b1≦0.80. The numerical value represented by c1 preferably satisfies 0.05≦c1≦0.55, and more preferably satisfies 0.10≦c1≦0.50. The numerical value represented by d1 preferably satisfies 0.02≦d1≦0.60, more preferably satisfies 0.05≦d1≦0.55, and satisfies 0.10≦d1≦0.50. is more preferred. The numerical values represented by c1 and d1 preferably satisfy 0.10≦c1+d1≦0.55, more preferably 0.20≦c1+d1≦0.50. Preferred specific examples of the lithium transition metal oxide represented by the compositional formula (2) include LiNi _0.85 Co 0.10 Al _0.05 O ₂ and LiNi _0.80 Co _0.15 Al 0.85 Co _0.10 Al 0.05 O _{2 . 05O2 , Li1.0Ni0.70Co0.15Mn0.15O2 , LiNi0.5Co0.2Mn0.3O2 , Li1.05Ni0.50Co0.20 _ _ _ _ _ _ _} Mn _0.30 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ and the like.

In each composition formula, M preferably contains Mn or Al, more preferably Mn. This is because the structural stability of the lithium transition metal oxide is enhanced, and structural deterioration during repeated charging and discharging is suppressed.

[2-2-1-2. Foreign element introduction]
Further, the lithium-transition metal composite oxide may contain an element (foreign element) other than the elements included in the above composition formula.

[2-2-1-3. surface coating]
A positive electrode active material having a different composition (surface adhering substance) attached to the surface of the positive electrode active material may be used. Examples of the surface adhering substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate.

These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending them in a solvent, impregnating and adding them to the positive electrode active material, and drying the material.

The amount of the surface-adhering substance is preferably 1 μmol/g or more, preferably 10 μmol/g or more, and usually 1 mmol/g or less, relative to the positive electrode active material.

In the present specification, a positive electrode active material having the above-described surface-attached substance attached to its surface is also referred to as a "positive electrode active material."

[2-2-1-4. blend]
In addition, these positive electrode active materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

[2-2-2. Configuration and Manufacturing Method of Positive Electrode]
The configuration and manufacturing method of the positive electrode will be described below. In this embodiment, the positive electrode using the positive electrode active material can be manufactured by a conventional method. That is, a positive electrode active material, a binder, and, if necessary, a conductive material, a thickening agent, and the like are dry-mixed to form a sheet, which is crimped to a positive electrode current collector, or these materials are mixed with a water-based The positive electrode is formed by a coating method in which a positive electrode active material layer is formed on the current collector by dissolving or dispersing the slurry in a liquid medium such as a solvent or an organic solvent to form a slurry, applying the slurry to the current collector, and drying the slurry. Obtainable. Further, for example, the positive electrode active material described above may be roll-molded into a sheet electrode, or may be compression-molded into a pellet electrode.

A case where the slurry is sequentially applied to the positive electrode current collector and dried will be described below.

[2-2-2-1. Active material content]
The content of the positive electrode active material in the positive electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[2-2-2-2. Conductive material]
Any known conductive material can be used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon-based materials such as amorphous carbon such as needle coke; One type of conductive material may be used alone, or two or more types may be used together in any combination and ratio. The conductive material is used so as to be contained in the positive electrode active material layer generally in an amount of 0.01% by mass or more and 50% by mass or less.

[2-2-2-3. Binder]
As the binder used for producing the positive electrode active material layer, for example, when the positive electrode active material layer is formed by a coating method, if it is a material that is dissolved or dispersed in the liquid medium for slurry, the type is Although not particularly limited, fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, etc. from weather resistance, chemical resistance, heat resistance, flame retardancy, etc.; CN group-containing such as polyacrylonitrile, polyvinylidene cyanide Polymers and the like are preferred.

Mixtures, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, etc. of the above polymers can also be used. In addition, a binder may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

When a resin is used as the binder, the weight-average molecular weight of the resin is arbitrary as long as it does not significantly impair the effects of the present invention. When the molecular weight is within this range, the strength of the electrode is improved, and the electrode can be suitably formed.

The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less.

[2-2-2-4. current collector]
The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum. Among them, aluminum is preferable.

Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. Among these, a metal foil or a metal thin film is preferable. Incidentally, the metal thin film may be appropriately formed in a mesh shape.

When the shape of the current collector of the positive electrode is plate-like, film-like, or the like, the thickness of the current collector is arbitrary, but is usually 1 μm or more and 1 mm or less.

[2-2-2-5. Thickness of positive electrode plate]
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the positive electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the positive electrode plate is On the other hand, usually 10 μm or more,
500 μm or less.

[2-2-2-6. Electrode density]
The positive electrode active material layer obtained by coating and drying is preferably densified by hand pressing, roller pressing, or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer present on the current collector is usually 1.5 g/cm ³ or more and 4.5 g/cm ³ or less.

[2-2-2-7. Surface coating of positive electrode plate]
In addition, the positive electrode plate may be one in which a substance having a composition different from that of the positive electrode plate is attached to the surface of the positive electrode plate. The same substances are used.

[2-3. negative electrode]
The negative electrode is not particularly limited as long as it can occlude and release metal ions (for example, lithium ions), but preferably has a negative electrode active material on at least part of the current collector surface.

[2-3-1. Negative electrode active material]
The negative electrode active material used for the negative electrode is not particularly limited as long as it can electrochemically intercalate and deintercalate metal ions (for example, lithium ions). Specific examples include a carbonaceous material, a material containing a metal element capable of being alloyed with Li and/or a metalloid element capable of being alloyed with Li (in this specification, a metal element capable of being alloyed with Li and/or materials containing metalloid elements, etc.), lithium-containing metal composite oxide materials, mixtures thereof, and the like. Among these, in terms of good cycle characteristics and safety and excellent continuous charging characteristics, carbon-based materials, materials containing metal elements and / or metalloid elements that can be alloyed with Li, and alloys with Li It is preferred to use mixtures of materials containing possible metallic and/or semi-metallic elements and carbonaceous materials. These may be used singly or in combination of two or more.

[2-3-1-1. carbon-based materials]
Carbon-based materials include natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite. Among them, natural graphite is preferable. One type of carbonaceous material may be used alone, or two or more types may be used together in any combination and ratio.

Examples of natural graphite include scale-like graphite, scale-like graphite, and/or graphite particles obtained by subjecting these graphites to a treatment such as spheroidization and densification. Among these, spherical or ellipsoidal graphite particles subjected to a spheroidization treatment are particularly preferable from the viewpoint of the packing properties of the particles and the charge/discharge rate characteristics.

The average particle size (d50) of graphite particles is usually 1 μm or more and 100 μm or less.

[2-3-1-2. Physical properties of carbonaceous materials]
The carbonaceous material as the negative electrode active material preferably satisfies at least one of the physical properties, shape, and other characteristics shown in the following (1) to (4), and particularly preferably satisfies a plurality of them at the same time. .

(1) X-ray diffraction parameter The d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction of the carbonaceous material according to the Gakushin method is usually 0.335 nm or more and 0.360 nm or less. In addition, the crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction according to the Gakushin method is usually 1.0 nm or more.

(2) Volume-Based Average Particle Size The volume-based average particle size of the carbonaceous material is the volume-based average particle size (median diameter) determined by the laser diffraction/scattering method, and is usually 1 μm or more and 100 μm or less.

(3) Raman R value and Raman half-value width The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectroscopy, and is usually 0.01 or more and 1.5 or less.

The Raman half-value width of the carbonaceous material near 1580 cm ⁻¹ is not particularly limited, but is usually 10 cm ⁻¹ or more and 100 cm ⁻¹ or less.

(4) BET Specific Surface Area The BET specific surface area of the carbonaceous material is the value of the specific surface area measured using the BET method, and is usually 0.1 m ² ·g ⁻¹ or more and 100 m ² ·g ⁻¹ or less.
Two or more carbonaceous materials having different properties may be contained in the negative electrode active material. The properties here mean X-ray diffraction parameters, volume-based average particle size, Raman R value, Raman half width and BET specific surface area.

Preferred examples include that the volume-based particle size distribution is not bilaterally symmetrical about the median diameter, that two or more carbonaceous materials having different Raman R values are contained, and that carbonaceous materials having different X-ray parameters are used. Containing 2 or more types, etc. are mentioned.

[2-3-1-3. A material containing a metal element and/or a metalloid element and/or a metalloid element that can be alloyed with Li]
Any conventionally known material containing a metal element and/or metalloid element that can be alloyed with Li can be used. , As, and Zn. In addition, when the material containing a metal element and/or metalloid element that can be alloyed with Li contains two or more elements, the material may be an alloy material made of an alloy of these metals.

In addition, oxides, nitrides, carbides, and the like can be cited as materials of the metal element and/or metalloid element that can be alloyed with Li. These may contain two or more kinds of metal elements and/or metalloid elements that can be alloyed with Li.

Among them, metal Si (hereinafter sometimes referred to as Si) or Si-containing inorganic compounds are preferable from the viewpoint of increasing the capacity.

In addition, the material of the metal element and/or metalloid element that can be alloyed with Li may already be alloyed with Li at the time of manufacturing the negative electrode, which will be described later.

In this specification, Si or Si-containing inorganic compounds are collectively referred to as Si compounds. Specific examples of Si compounds include SiO _x (0≦x≦2). Specific examples of metal compounds alloyed with Li include Li _y Si (0<y≦4.4), Li ₂ SiO _2+z (0<z≦2), and the like. Si oxide (SiO _x1 , 0<x1 ≤ 2) is preferable as the Si compound because it has a larger theoretical capacity than graphite, or amorphous Si or nano-sized Si crystals are preferred as alkali ions such as lithium ions. is easy to enter and exit, and it is possible to obtain a high capacity.

When the material containing the metal element and/or metalloid element that can be alloyed with Li is particles, the average particle diameter (d50) is usually 0.01 μm or more and 10 μm or less from the viewpoint of cycle life.

[2-3-1-4. A mixture of particles of a material containing a metallic element and/or semi-metallic element that can be alloyed with Li and graphite particles]
A mixture of graphite particles and particles of a material containing a metal element and/or metalloid element that can be alloyed with Li used as a negative electrode active material contains the metal element and/or metalloid element that can be alloyed with Li. It may be a mixture in which the particles of the material containing and the graphite particles are mixed in the state of particles of the material independent of each other, or a material containing a metal element and / or metalloid element that can be alloyed with Li. A composite in which the particles are present on the surface or inside the graphite particles may also be used.

The content ratio of the particles of the material containing the metal element and/or metalloid element that can be alloyed with Li to the total of the particles of the material containing the metal element and/or metalloid element that can be alloyed with Li and the graphite particles , Usually 1% by mass or more and 99% by mass or less, preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 20% by mass or less, still more preferably 2% by mass or more and 10% by mass % or less.

[2-3-1-5. Lithium-containing metal composite oxide material]
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 ions. A material is preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as "lithium-titanium composite oxide") is more preferable, and lithium-titanium composite oxide having a spinel structure greatly reduces the output resistance, so it is particularly preferable.

Also, lithium and/or titanium in the lithium-titanium composite oxide may be substituted with other metal elements such as at least one element selected from the group consisting of Al, Ga, Cu and Zn.

Li _4/3 Ti _5/3 O ₄ , Li ₁ Ti ₂ O ₄ and Li _4/5 Ti _11/5 O ₄ are preferable as the lithium titanium composite oxide. Li4/ _3Ti4 / _3Al1 / _{3O4 ,} for example, is preferable as the lithium-titanium composite oxide in which part of lithium and/or titanium is replaced with another element.

[2-3-2. Structure and Manufacturing Method of Negative Electrode]
Any known method may be used to manufacture the negative electrode as long as it does not significantly impair the effects of the present invention. For example, to the negative electrode active material, a binder, a liquid medium such as an aqueous solvent or an organic solvent, and, if necessary, a thickener, a conductive material, a filler, etc. are added to form a slurry, which is applied to the current collector. can be produced by drying and then pressing to form a negative electrode active material layer. It can also be produced by forming a negative electrode active material layer on a current collector by sputtering a material that forms the negative electrode active material.

[2-3-2-1. Active material content]
The content of the negative electrode active material in the negative electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[2-3-2-2. Electrode density]
The negative electrode active material layer obtained by coating and drying is preferably densified by hand pressing, roller pressing, or the like in order to increase the filling density of the negative electrode active material. The electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, but the density of the negative electrode active material layer present on the current collector is usually 1 g cm ^-3 or more and 2.2 g cm ^-3 or less. is.

[2-3-2-3. Thickener]
Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, but specific examples include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

When a thickener is used, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less.

[2-3-2-4. Binder]
The binder that binds the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolytic solution and the liquid medium used in electrode production.

Specific examples include rubber-like polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), ethylene-propylene rubber; polyvinylidene fluoride, polytetrafluoroethylene, Examples thereof include fluorine-based polymers such as tetrafluoroethylene-ethylene copolymers. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

The ratio of the binder to the negative electrode active material is usually 0.1% by mass or more and 20% by mass or less.

In particular, when the binder contains a rubber-like polymer represented by SBR as a main component, the ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more and 5% by mass or less. . Further, when the binder contains a fluorine-based polymer represented by polyvinylidene fluoride as a main component, the ratio of the binder to the negative electrode active material is preferably 1% by mass or more and 15% by mass or less. .

[2-3-2-5. current collector]
As the current collector for holding the negative electrode active material, any known current collector can be used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable in terms of ease of processing and cost.

Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. Among these, a metal foil or a metal thin film is preferable. Incidentally, the metal foil and the metal thin film may be appropriately formed in a mesh shape.

When the shape of the current collector of the negative electrode is plate-like, film-like, or the like, the thickness of the current collector is arbitrary, but is usually 1 μm or more and 1 mm or less.

[2-3-2-6. Thickness of negative electrode plate]
The thickness of the negative electrode (also referred to as “negative plate”) is designed according to the positive electrode to be used, and is not particularly limited. The thickness of is usually 15 μm or more and 300 μm or less.

[2-3-2-7. Surface coating of negative electrode plate]
Further, the negative electrode plate may have a surface adhered with a substance having a composition different from that of the negative electrode active material (surface adhering substance). Examples of the surface adhering substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate.

[2-4. Separator]
A separator is usually interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the separator is usually impregnated with the non-aqueous electrolytic solution.

The material and shape of the separator are not particularly limited, and known materials can be arbitrarily adopted as long as they do not significantly impair the effects of the present invention.

[2-5. battery design]
[2-5-1. Electrode group]
The electrode group has a laminate structure in which the positive electrode plate and the negative electrode plate are interposed between the separators, and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween. Either is fine. The ratio of the volume of the electrode group to the internal volume of the battery is usually 40% or more and 90% or less.

[2-5-2. Current collection structure]
When the electrode group has the above-described laminated structure, a structure in which the metal core portions of the electrode layers are bundled and welded to a terminal is preferably used. A structure in which a plurality of terminals are provided in an electrode to reduce resistance is also preferably used. When the electrode group has the wound structure described above, the internal resistance can be reduced by providing a plurality of lead structures for each of the positive electrode and the negative electrode and bundling them around the terminal.

[2-5-3. Protective element]
Protective elements include PTC (Positive Temperature Coefficient) elements whose resistance increases as heat is generated by excessive current, thermal fuses, thermistors, and valves that cut off the current flowing through the circuit due to a sudden increase in battery internal pressure or internal temperature during abnormal heat generation. (current cut-off valve) or the like can be used. It is preferable to select the protective element under the condition that it does not operate under normal high-current use, and it is more preferable to design such that abnormal heat generation and thermal runaway do not occur even without the protective element.

[2-5-4. exterior body]
A non-aqueous electrolyte secondary battery is generally configured by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body (exterior case). There is no restriction on this exterior body, and any known one can be employed as long as it does not significantly impair the effects of the present invention.

The material of the exterior case is not particularly limited as long as it is stable with respect to the non-aqueous electrolytic solution used, but from the viewpoint of weight reduction, aluminum or aluminum alloy metal or laminate film is preferably used.

The exterior case using the above metals has a sealed structure by welding the metals together by laser welding, resistance welding, or ultrasonic welding, or a crimped structure using the above metals via a resin gasket. There are things to do.

[2-5-5. shape]
Moreover, the shape of the exterior case is also arbitrary, and may be cylindrical, rectangular, laminated, coin-shaped, large-sized, or the like.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The compounds used in Examples and Comparative Examples are shown in Table 1 below. Compounds 1 to 3 represented by the general formula (1) were synthesized by the method shown in Synthesis Examples below. Compound 4 was a Sigma-Aldrich reagent, and compounds 5 and 6 were Tokyo Kasei reagents.

<Synthesis of compound represented by general formula (1)>
Compounds 1 to 3 represented by general formula (1) used in this example were synthesized by the following method.

<Synthesis example>
Various analysis methods in the following synthesis examples are as follows.

[Nuclear magnetic resonance (NMR) analysis]
¹ H and ¹³ C-NMR were measured at 400 and 101 MHz, respectively, using a Bruker 400 Ultrashield. Samples were dissolved in deuterated chloroform (CDCl ₃ ) and measured.

[Gas chromatography (GC) analysis]
100 μL of sample was dissolved in 1 mL of organic solvent (diethyl ether). The resulting solution was analyzed with a GC analyzer (GC-2025 manufactured by Shimadzu Corporation). The conditions were as follows.
Column: DB-1 (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm, manufactured by Agilent Technologies)
Detector: FID
Temperature: 40°C→280°C, increased at 10°C/min.
Purity was determined from peak area %.

<Synthesis Example 1> Synthesis of compound 1 (2,2,5,5-tetramethyl-1,3,2-dioxasilinane) 2,2-dimethyl-1,3-propanediol (5.00 g, 48.0 mmol) was dissolved in diethyl ether (300 mL) and triethylamine (14.6 mL, 106 mmol) was added. A solution of dichlorodimethylsilane (5.79 mL, 48.0 mmol) in diethyl ether (50 mL) was added dropwise over 2 hours while stirring under ice cooling. After stirring for 2 hours at room temperature, the precipitate was filtered off. After distilling off the solvent, purification by distillation gave 2,2,5,5-tetramethyl-1,3,2-dioxasilinane (2.54 g, 15.8 mmol). Purity estimated by GC analysis was 98%. The analysis results of ¹ H-NMR and ¹³ C-NMR were as follows.
¹ H-NMR (400 MHz, CDCl3): δ = 3.66 (s, 4H), 0.96 (s, 6H), 0.20 (s, 6H)
¹³ C-NMR (101 MHz, CDCl3): δ = 73.6, 35.2, 21.9, -2.6

<Synthesis Example 2> Synthesis of compound 2 (2,5,5-trimethyl-2-vinyl-1,3,2-dioxasilinane) 2,2-dimethyl-1,3-propanediol (5.00 g, 48.0 mmol ) was dissolved in diethyl ether (300 mL) and triethylamine (14.6 mL, 106 mmol) was added. A solution of dichloromethylvinylsilane (6.21 mL, 48.0 mmol) in diethyl ether (50 mL) was added dropwise over about 1 hour while stirring under ice cooling. After stirring at room temperature for 5 hours, the precipitate was filtered off. After distilling off the solvent, purification by distillation gave 2,5,5-trimethyl-2-vinyl-1,3,2-dioxasilinane (2.67 g, 15.5 mmol). Purity estimated by GC analysis was 98%. The analysis results of ¹ H-NMR and ¹³ C-NMR were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ): δ = 6.14-6.08 (m, 1H), 6.03-5.93 (m, 2H), 3.74 (d, J = 10.8Hz , 2H), 3.64 (d, J = 11.0 Hz, 2H), 1.07 (s, 3H), 0.87 (s, 3H), 0.27 (s, 3H)
¹³ C-NMR (101 MHz, CDCl ₃ ): δ=135.6, 133.1, 73.8, 35.2, 22.0, 21.8, −3.8

<Synthesis Example 3> Synthesis of compound 3 (2-methyl-2-vinyl-1,3,2-dioxasilinane) 1,3-propanediol (6.00 g, 78.8 mmol) was dissolved in diethyl ether (500 mL). , triethylamine (24 mL, 173 mmol) was added. A solution of dichloromethylvinylsilane (10.2 mL, 78.8 mmol) in diethyl ether (50 mL) was added dropwise while stirring under ice cooling. After stirring at room temperature for 2 hours, the reaction was filtered and the filtrate was concentrated. By purifying the resulting crude product by distillation, 2-methyl-2-vinyl-1,3,2-dioxasilinane (3.58 g, 24.8 mmol) was obtained. GC analysis gave an estimated purity of 94%. The analysis results of ¹ H-NMR and ¹³ C-NMR were as follows.
¹ H-NMR (400 MHz, CDCl3): δ = 6.14-6.00 (m, 2H), 5.94 (dd, J = 19.6, 5.1 Hz, 1H), 4.10-4. 08 (m, 4H), 2.03-1.96 (m, 1H), 1.82-1.75 (m, 1H), 0.25 (s, 3H)
¹³ C-NMR (101 MHz, CDCl3): δ = 135.4, 133.9, 64.0, 31.7, -3.0

<Examples 1-1 to 1-3, Comparative Examples 1-1 to 1-3>
[Preparation of non-aqueous electrolytic solution]
In a dry argon atmosphere, a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio EC:DMC:EMC=3:4:3) was added with sufficiently dried LiPF as an electrolyte. ₆ was dissolved at 1.0 mol/L (12.2% by mass; as the concentration in the non-aqueous electrolytic solution). A reference electrolytic solution 1 was prepared by adding 1 part by mass of vinylene carbonate to 100 parts by mass of this electrolytic solution. Compounds 1, 2 and 4 were added in the amounts shown in Table 2 below to prepare non-aqueous electrolytic solutions. The "content (parts by mass)" in the table is the content when the reference electrolyte solution 1 is 100 parts by mass.

[Fabrication of half-cell]
Using a SiO thin film in which SiO is sputtered on a copper foil as a negative electrode, a sufficient amount of metallic lithium foil as a counter electrode, a non-aqueous electrolytic solution and a separator made of polyethylene, SiO thin film, non-aqueous electrolytic solution, separator, metallic lithium foil Layered in order. The thus-obtained battery element was placed in a 2032 coin-type battery case, and crimped with a crimping machine to prepare a coin-type half cell.

[Run-in]
The resulting half-cell was charged at 25° C. at a constant current corresponding to 0.05 C to 5 mV, then charged at a constant voltage of 5 mV until the current value reached 0.01 C, and then charged at a constant current of 0.1 C. It was discharged to 1500mV. This was repeated for 3 cycles to stabilize the half-cell and complete the break-in.

[Evaluation of capacity retention rate during repeated charging and discharging]
After the half-cell, which had been run-in, was charged at a constant current corresponding to 0.05 C to 5 mV, then charged at a constant voltage of 5 mV until the current value reached 0.01 C, and discharged at a constant current of 0.1 C to 1500 mV. bottom. This discharge amount was defined as the discharge capacity in the first cycle. After that, charging to 5 mV and discharging to 1500 mV were repeated 150 times. Charge/discharge was performed once every 30 times under the above conditions. Others were charged at a constant current corresponding to 0.5C up to 5mV, and then charged at a constant voltage of 5mV until the current value reached 0.05C. The battery was charged and discharged under the condition of discharging to 1500 mV at a constant current of 1C. The amount of discharge at 0.1 C at the 151st cycle was defined as the discharge capacity at the 151st cycle. Table 2 below shows the capacity retention rate (%) during repeated charging and discharging, calculated from (discharge capacity at 151st cycle)÷(discharge capacity at 1st cycle)×100.

From Table 2, Examples 1-1 to 1-3 using the electrolytic solution containing the compound represented by the general formula (1), Comparative Example 1-1 using the reference electrolytic solution as it is and other compounds As compared with Comparative Examples 1-2 and 1-3 using the containing electrolyte, it can be seen that the capacity retention rate during repeated charging and discharging is superior.

<Examples 2-1 to 2-2, Comparative Examples 2-1 to 2-2>
[Preparation of positive electrode]
90 parts by mass of lithium-nickel-cobalt-manganese composite oxide (Li _1.0 Ni _0.5 Co _0.2 Mn _0.3 O ₂ ) as a positive electrode active material and 7 parts by mass of acetylene black as a conductive material; 3 parts by mass of polyvinylidene fluoride (PVdF) as an adhesive was mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly coated on both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to form a positive electrode.

[Preparation of negative electrode]
To 98 parts by mass of natural graphite, 1 part by mass of an aqueous dispersion of sodium carboxymethylcellulose (concentration of 1% by mass of sodium carboxymethylcellulose) and an aqueous dispersion of styrene-butadiene rubber (styrene-butadiene rubber concentration of 50% by mass) was added and mixed with a disperser to form a slurry. The resulting slurry was applied to one side of a copper foil having a thickness of 10 μm, dried, and then pressed to form a negative electrode.

[Preparation of non-aqueous electrolytic solution]
In a dry argon atmosphere, a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio EC:DMC:EMC=3:4:3) was added with sufficiently dried LiPF as an electrolyte. Reference electrolyte solution 2 was prepared by dissolving ₆ at 1.0 mol/L (12.2% by mass; concentration in non-aqueous electrolyte solution). Compounds 2, 3 and 5 were added in the amounts shown in Table 3 below to prepare non-aqueous electrolytic solutions. The "content (parts by mass)" in the table is the content when the standard electrolyte solution 2 is 100 parts by mass.

[Manufacture of non-aqueous electrolyte battery]
A battery element was produced by stacking the positive electrode, the negative electrode, and the separator made of polyethylene in the order of negative electrode, separator, and positive electrode. After inserting this battery element into a bag made of a laminate film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer so that the terminals of the positive electrode and the negative electrode protrude, the non-aqueous electrolytic solution prepared as described above is placed in the bag. It was injected into the inside and vacuum-sealed to fabricate a laminate type non-aqueous electrolyte battery.

<Evaluation of non-aqueous electrolyte battery>
[Initial conditioning]
In a constant temperature bath at 25 ° C., the non-aqueous electrolyte battery prepared by the above method is exposed to a current equivalent to 0.025 C (1 C indicates a current value that takes 1 hour to charge or discharge. The same applies hereinafter.) After constant-current charging to 3.6V at , constant-current-constant-voltage charging (hereinafter referred to as CC-CV charging) to 4.2V at 0.17C, and then discharging to 2.5V at 0.17C. . Subsequently, constant current-constant voltage charging was performed at 0.17C to 4.1V. After that, aging was performed by holding at 60° C. for 24 hours. After that, discharge to 2.5V at 0.17C, further CC-CV charge to 4.2V at 0.17C, discharge to 2.5V at 0.2C, and then to 3.7V at 0.17C. Initial conditioning was performed by charging.

[Charging storage test]
After the initial conditioning, the non-aqueous electrolyte battery was again charged by CC-CV to 4.3 V at 0.17 C, and then stored at high temperature at 60° C. for 2 weeks. After that, the non-aqueous electrolyte battery was sufficiently cooled, discharged at 0.17C to 2.5V, further CC-CV charged to 4.2V at 0.17C, and then charged at 0.2C to 2.5V. The nonaqueous battery was stabilized by discharging to 5V and charging to 3.7V at 0.17C. The battery was immersed in an ethanol bath to measure the volume, and the amount of generated gas was obtained from the change in volume before and after the storage test. Table 3 below shows the values of the high-temperature charged and stored gas amount when the charged and stored gas amount of Comparative Example 2-1 is set to 100.

From Table 3, Examples 2-1 and 2-2 using the electrolytic solution containing the compound represented by the general formula (1), Comparative Example 2-1 using the reference electrolytic solution 2 as it is and other compounds It can be seen that the amount of gas after high-temperature charging and storage is suppressed as compared with Comparative Example 2-2 using the electrolytic solution containing. Among the compounds represented by the general formula (1), Examples 2-1 and 2-2 containing compounds in which R ¹ is a hydrocarbon group having a carbon-carbon unsaturated bond are particularly suitable for high-temperature charge storage. It can be seen that the subsequent gas suppression effect is high.

<Examples 3-1 to 3-2, Comparative Example 3-1>
[Preparation of positive electrode]
₉₀ parts by mass of lithium-nickel-cobalt-manganese composite oxide ( _{Li1.0Ni0.70Co0.15Mn0.15O2 )} as _a positive electrode active _material , 7 parts by mass of acetylene black as a conductive material, and 3 parts by mass of polyvinylidene fluoride (PVdF) as an adhesive was mixed with a disperser in an N-methylpyrrolidone solvent to form a slurry. This was uniformly coated on both sides of an aluminum foil having a thickness of 15 μm, dried, and then pressed to form a positive electrode.

[Preparation of negative electrode]
Negative electrode active material (natural graphite: SiO = 95:5 weight ratio) 98 parts by weight, 1 part by weight of aqueous dispersion of carboxymethylcellulose sodium (concentration of carboxymethylcellulose sodium 1% by weight) as a thickener and binder, and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50 mass %) was added and mixed with a disperser to form a slurry. The resulting slurry was applied to one side of a copper foil having a thickness of 10 μm, dried, and then pressed to form a negative electrode.

[Preparation of non-aqueous electrolytic solution]
In a dry argon atmosphere, a mixture of ethylene carbonate (EC), ethylmethyl carbonate (EMC), and diethyl carbonate (DEC) (volume ratio EC:EMC:DEC=3:4:3) was added with sufficiently dried LiPF as an electrolyte. ₆ was dissolved at 1.2 mol/L (14.8% by mass; concentration in the non-aqueous electrolytic solution). A reference electrolytic solution 3 was prepared by adding 2 parts by mass of vinylene carbonate to 100 parts by mass of this electrolytic solution. Compounds 1 and 2 were added in the amounts shown in Table 4 below to prepare a non-aqueous electrolytic solution. The "content (parts by mass)" in the table is the content when the standard electrolyte solution 3 is 100 parts by mass.

[Manufacture of non-aqueous electrolyte battery]
A battery element was produced by stacking the positive electrode, the negative electrode, and the separator made of polyolefin in the order of negative electrode, separator, and positive electrode. After inserting this battery element into a bag made of a laminate film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer so that the terminals of the positive electrode and the negative electrode protrude, the non-aqueous electrolytic solution prepared as described above is placed in the bag. It was injected into the inside and vacuum-sealed to fabricate a laminate type non-aqueous electrolyte battery.

<Evaluation of non-aqueous electrolyte battery>
[Initial conditioning]
In a constant temperature bath at 25°C, the non-aqueous electrolyte battery prepared by the above method was constant current charged to 3.72V at a current corresponding to 0.05C, and then discharged to 2.5V at 0.2C. Subsequently, constant current-constant voltage charging was performed at 0.2C to 4.1V. Aging was carried out by holding at 60° C. for 24 hours. After cooling to 25°C, it was discharged to 2.5V at 0.2C. Thereafter, CC-CV charging to 4.2V at 0.2C and discharging to 2.5V at 0.2C were repeated twice. Finally, initial conditioning was completed by charging to 3.72V at 1.0C.

[Evaluation of capacity retention rate during repeated charging and discharging]
In a constant temperature bath at 45° C., the non-aqueous electrolyte battery after the initial conditioning was subjected to constant current-constant voltage discharge to 2.7 V at a constant current corresponding to 1.0C. After that, constant current-constant voltage charging to 4.2 V at a current corresponding to 1.0 C, followed by constant current-constant voltage discharging to 2.7 V at 1.0 C was defined as one cycle, and this was repeated 200 cycles. . Table 4 below shows the capacity retention rate (%) during repeated charge/discharge calculated from (discharge current capacity at 200th cycle)/(discharge current capacity at 1st cycle)×100.

From Table 4, Examples 3-1 and 3-2 using the electrolytic solution containing the compound represented by the general formula (1) are compared to Comparative Example 3-1 using the reference electrolytic solution 3 as it is, It can be seen that the capacity retention rate during repeated charging and discharging is improved.

Claims (6)

A non-aqueous electrolytic solution containing a compound represented by the following general formula (1).

(In general formula (1), R ¹ and R ² are each independently a hydrogen atom or a hydrocarbon group, and X represents a divalent hydrocarbon group forming a ring together with the --O--Si--O-- bond. However, the hydrogen atom of the carbon of X may be substituted with a halogen atom.) 2. The non-aqueous electrolytic solution according to claim 1, wherein X in the general formula (1) has 2 or 3 carbon atoms forming a ring together with the --O--Si--O-- bond. The total content of the compound represented by the general formula (1) is 0.001% by mass or more and 30% by mass or less with respect to the total amount of the non-aqueous electrolyte solution, non-aqueous system according to claim 1 or 2 Electrolyte. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to claim 1 or 2. 5. The non-aqueous electrolyte battery according to claim 4, wherein the negative electrode contains a negative electrode active material, and the negative electrode active material contains metal Si or Si oxide. 5. The non-aqueous electrolyte battery according to claim 4, wherein the positive electrode contains a positive electrode active material, and the positive electrode active material is a metal oxide represented by the following compositional formula (2).
Li _a1 Ni _b1 Co _c1 M _d1 O ₂ (2)
(In the above formula (2), a1, b1, c1 and d1 are 0.90 ≤ a1 ≤ 1.10, 0.40 ≤ b1 ≤ 0.98, 0.01 ≤ c1 < 0.50, 0.01 ≤ d1 < 0.50 and satisfies b1 + c1 + d1 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er.)