JP2014170689A - Nonaqueous electrolyte and lithium secondary battery - Google Patents

Abstract

Provided are a non-aqueous electrolyte that can significantly improve low-temperature discharge characteristics while improving storage characteristics of the battery, and a lithium secondary battery including the non-aqueous electrolyte.
At least one selected from cyclic sulfate compounds such as 2,2-dioxo-1,3,2-dioxathiolane and unsaturated sultone compounds such as 1,3-prop-1-ene sultone, and phosphazene compounds And a nonaqueous electrolytic solution containing at least one selected from halogenated phosphoric acid ester compounds.
[Selection figure] None

Description

  The present invention relates to a non-aqueous electrolyte, and a chargeable / dischargeable lithium secondary battery used for a power source of a portable electronic device, a vehicle-mounted device, and power storage.

2. Description of the Related Art In recent years, lithium secondary batteries have been widely used as electronic devices such as mobile phones and laptop computers, electric vehicles, and power storage sources. In particular, recently, there has been a rapid increase in demand for batteries with high capacity, high output, and high energy density that can be mounted on hybrid vehicles and electric vehicles.
The lithium secondary battery is mainly composed of a positive electrode and a negative electrode containing a material capable of occluding and releasing lithium, and a non-aqueous electrolyte containing a lithium salt and a non-aqueous solvent.
As the positive electrode active material used for the positive electrode, for example, lithium metal oxides such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , and LiFePO ₄ are used.
In addition, as the non-aqueous electrolyte, a mixed solvent (non-aqueous solvent) of carbonates such as ethylene carbonate, propylene carbonate, ethylene carbonate, and methyl carbonate, LiPF ₆ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiN ( A solution in which a Li electrolyte such as SO ₂ CF ₂ CF ₃ ) ₂ is mixed is used.
On the other hand, negative electrode active materials used for negative electrodes include metal lithium, metal compounds capable of occluding and releasing lithium (metal simple substance, oxide, alloy with lithium, etc.) and carbon materials, particularly lithium. Lithium secondary batteries using coke, artificial graphite, and natural graphite that can be occluded and released have been put into practical use.

Among battery performances, particularly for lithium secondary batteries for automobiles, higher output and longer life are required. Solvent formed on the surface of the negative electrode is one of the factors that increase battery resistance, where minimization of battery resistance under various operating conditions and improvement of battery life performance are major issues. Films of decomposition products and inorganic salts are known. In general, the negative electrode surface is known to undergo a reductive decomposition reaction of an electrolytic solution because lithium metal is present in the negative electrode active material under charging conditions. If such reductive decomposition occurs continuously, the resistance of the battery increases, the charge / discharge efficiency decreases, and the energy density of the battery decreases. On the other hand, it is known that a deterioration reaction with time also occurs in the positive electrode, and the resistance continuously increases, resulting in a decrease in battery performance. In order to overcome these problems, attempts have been made to add various compounds to the electrolytic solution.
For example, attempts have been made to improve battery performance by incorporating various cyclic sulfate compounds in a non-aqueous electrolyte (see, for example, Patent Documents 1 to 5). In addition, for example, attempts have been made to improve battery performance by adding unsaturated sultone to the non-aqueous electrolyte (see, for example, Patent Documents 6 and 7).

JP-A-10-189042 JP 2003-151623 A JP 2003-308875 A JP 2004-22523 A JP 2005-011762 A Japanese Patent No. 4190162 Japanese Patent No. 4424895

However, there has been a problem that both the improvement of the low-temperature discharge characteristics and the improvement of the storage characteristics of the battery are not sufficiently satisfied only by the examination so far.
In particular, the addition of the cyclic sulfate ester compound and the unsaturated sultone compound described in each of the above documents contributes to the improvement of the battery life, but there is a problem that the low-temperature discharge characteristics are insufficient.

  The present invention has been made to meet the above-mentioned problems, and an object of the present invention is to include a non-aqueous electrolyte that can significantly improve low-temperature discharge characteristics while improving the storage characteristics of the battery, and the non-aqueous electrolyte. It is to provide a lithium secondary battery.

As a result of intensive studies on the above problems, the present inventor is able to remarkably improve the low-temperature discharge characteristics while improving the storage characteristics of the battery by adding a specific compound to the non-aqueous electrolyte of the secondary battery. The present invention has been completed.
That is, the means for solving the problems of the present invention are as follows.

<1> A nonaqueous electrolytic solution containing at least one of a cyclic sulfate compound and an unsaturated sultone compound, and at least one of a phosphazene compound and a halogenated phosphate compound.

<2> The nonaqueous electrolytic solution according to <1>, wherein the cyclic sulfate compound is a cyclic sulfate compound represented by the following general formula (I).

In general formula (I), R ¹ and R ² are each independently represented by a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a group represented by general formula (II), or general formula (III). Or a group that together forms a benzene ring or a cyclohexyl ring together with the carbon atom to which R ¹ is bonded and the carbon atom to which R ² is bonded. In general formula (II), R ³ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or general formula (IV). Represents the group represented. The wavy line in general formula (II), general formula (III), and general formula (IV) represents a bonding position.

<3> The nonaqueous electrolytic solution according to <1> or <2>, wherein the unsaturated sultone compound is an unsaturated sultone compound represented by the following general formula (V).

In the general formula ^(V), R 4 ~R ⁷ are each independently a hydrogen atom, an alkyl group having a halogen atom, or a carbon number 1 to 6, n is an integer of 0 to 3.

<4> The nonaqueous electrolytic solution according to any one of <1> to <3>, wherein the phosphazene compound is a phosphazene compound represented by the following general formula (VI).

In the general formula (VI), R ^{8 to} R ¹³ each independently represent at least one selected from a halogen atom, an alkyl group, an aryl group, an alkoxy group, and an aryloxy group.

<5> The nonaqueous electrolytic solution according to any one of <1> to <4>, wherein the halogenated phosphate compound is the halogenated phosphate compound represented by the following general formula (VII): .

In general formula (VII), R ^{14 to} R ¹⁶ each independently represents at least one selected from an alkyl group that may be substituted with a halogen atom and an aryl group that may be substituted with a halogen atom. .

<6> At least a compound represented by the following general formula (VIII), a compound represented by the general formula (IX), a compound represented by the general formula (X), and a compound represented by the general formula (XI) The nonaqueous electrolytic solution according to any one of <1> to <5>, including one.

In general formula (VIII), M represents an alkali metal, Y represents a transition element, or a group 13, 14 or 15 element of the periodic table, b is an integer of 1 to 3, m is 1 to An integer of 4, n is an integer of 0 to 8, and q is 0 or 1. R ¹⁷ is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a hetero atom, and when q is 1 and m is 2 to 4, m R ^{17 s} may be bonded to each other. ¹⁵ is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (these groups are In the structure, a substituent or a hetero atom may be contained, and when n is 2 to 8, n R ^{18 s} may be bonded to each other to form a ring), or It represents a -Q ³ R ^19. Q ¹ , Q ² and Q ³ each independently represent O, S or NR ²⁰ , and R ¹⁹ and R ²⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or 1 to 1 carbon atoms. A halogenated alkyl group having 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a hetero atom in the structure; ^{And a} plurality of ¹⁹ or R ²⁰ may be bonded to each other to form a ring).

  In general formula (IX), X represents an alkali metal or a hydrocarbon group having 1 to 12 carbon atoms.

In the general formula (X), R ²¹ and R ²² each independently represent a hydrogen atom, a methyl group, an ethyl group, or a propyl group.

In general formula (XI), R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are each independently a hydrocarbon group having 1 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms which may be substituted with a fluorine atom. Represents an aryl group having 6 to 12 carbon atoms, a hydrogen atom, a fluorine atom, or a chlorine atom. However, R ^{23 to} R ²⁶ are not simultaneously hydrogen atoms.

<7> In any one of <1> to <6>, the total content of the cyclic sulfate compound and the unsaturated sultone compound is 0.01% by mass to 10% by mass of the total amount of the nonaqueous electrolytic solution. The non-aqueous electrolyte described.

<8> The total content of the phosphazene compound and the halogenated phosphoric acid ester compound is any one of <1> to <7>, which is 0.01% by mass to 30% by mass of the total amount of the non-aqueous electrolyte. The non-aqueous electrolyte described.

<9> Total of the compound represented by the general formula (VIII), the compound represented by the general formula (IX), the compound represented by the general formula (X), and the compound represented by the general formula (XI) The nonaqueous electrolytic solution according to <6>, wherein the content is 0.01% by mass to 10% by mass of the total amount of the nonaqueous electrolytic solution.

<10> Positive electrode, metallic lithium, lithium-containing alloy, metal or alloy that can be alloyed with lithium, oxide that can be doped / undoped with lithium ions, transition metal that can be doped / undoped with lithium ions A negative electrode containing, as a negative electrode active material, at least one selected from a nitride and a carbon material that can be doped / undoped with lithium ions, and the non-aqueous solution according to any one of <1> to <9> A lithium secondary battery including an electrolyte solution.

  According to the present invention, there is provided a non-aqueous electrolyte for use in a lithium secondary battery, which can improve the storage characteristics of the battery while significantly improving the low-temperature discharge characteristics, and a lithium containing the non-aqueous electrolyte. A secondary battery can be provided.

It is typical sectional drawing of the coin-type battery which shows an example of the lithium secondary battery (nonaqueous electrolyte secondary battery) of this invention.

The nonaqueous electrolytic solution of the present invention contains at least one of a cyclic sulfate ester compound and an unsaturated sultone compound, and at least one of a phosphazene compound and a halogenated phosphate ester compound.
That is, the nonaqueous electrolytic solution of the present invention is at least one selected from the group consisting of cyclic sulfate compounds and unsaturated sultone compounds, and at least one selected from the group consisting of phosphazene compounds and halogenated phosphate compounds. Seeds.

  The non-aqueous electrolyte of the present invention is a non-aqueous electrolyte that can remarkably improve the low-temperature discharge characteristics while improving the storage characteristics of the battery.

  Hereinafter, the components of the nonaqueous electrolytic solution of the present invention will be specifically described.

[Cyclic sulfate compound]
The cyclic sulfate compound of the present invention is preferably a compound represented by the following general formula (I).

In general formula (I), R ¹ and R ² are each independently represented by a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a group represented by general formula (II), or general formula (III). Or a group that together forms a benzene ring or a cyclohexyl ring together with the carbon atom to which R ¹ is bonded and the carbon atom to which R ² is bonded. In general formula (II), R ³ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or general formula (IV). Represents the group represented. The wavy line in general formula (II), general formula (III), and general formula (IV) represents a bonding position.

Specific examples of the “halogen atom” in the general formula (II) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
As the halogen atom, a fluorine atom is preferable.

  In the general formula (I), the “alkyl group having 1 to 6 carbon atoms” is a linear or branched alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, Isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, 2-methylbutyl, 1-methylpentyl, neopentyl, 1-ethylpropyl, hexyl, 3,3-dimethyl A specific example is a butyl group.

  As a C1-C6 alkyl group, a C1-C3 alkyl group is more preferable.

In the general formula (II), the “halogenated alkyl group having 1 to 6 carbon atoms” is a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, such as a fluoromethyl group and a difluoromethyl group. Group, trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroisopropyl group, perfluoro Specific examples include isobutyl, chloromethyl, chloroethyl, chloropropyl, bromomethyl, bromoethyl, bromopropyl, methyl iodide, ethyl iodide, propyl iodide and the like.
As the halogenated alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms is more preferable.

In the general formula (II), the “C 1-6 alkoxy group” is a linear or branched alkoxy group having 1 to 6 carbon atoms, and includes a methoxy group, an ethoxy group, a propoxy group, Propoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, 2-methylbutoxy group, 1-methylpentyloxy group, neopentyloxy group, 1-ethylpropoxy group, hexyloxy group Specific examples thereof include 3,3-dimethylbutoxy group.
As a C1-C6 alkoxy group, a C1-C3 alkoxy group is more preferable.

R ¹ and R ² in the general formula (I) are preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a group represented by the general formula (II) (in the general formula (II), R ³ is preferably a fluorine atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV). ), A group represented by the above formula (III), or a group that together forms a benzene ring or a cyclohexyl ring together with the carbon atom to which R ¹ is bonded and the carbon atom to which R ² is bonded.

R ¹ in the general formula (I) is more preferably a group represented by the general formula (II) (in the general formula (II), R ³ is a fluorine atom, an alkyl group having 1 to 3 carbon atoms. , A halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV) is particularly preferable), or represented by the formula (III). It is a group.
R ² in the general formula (I) is more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a group represented by the general formula (II) (in the general formula (II), R ³ is And a fluorine atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV). Or a group represented by the formula (III), more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.

When R ¹ in the general formula (I) is a group represented by the general formula (II), R ³ in the general formula (II) is a halogen atom, having 1 to 6 carbon atoms as described above. An alkyl group, a halogenated alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a group represented by the formula (IV), R ³ is more preferably a fluorine atom or a carbon number of 1 Or an alkyl group having 1 to 3, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV), and more preferably a fluorine atom, a methyl group, An ethyl group, a methoxy group, an ethoxy group, or a group represented by the formula (IV).
When R ² in the general formula (I) is a group represented by the general formula (II), a preferable range of R ^{3 in} the general formula (II) is as follows. ^This is the same as the preferred range of R ³ when ¹ is a group represented by the general formula (II).

As a preferable combination of R ¹ and R ² in the general formula (I), R ¹ is a group represented by the general formula (II) (in the general formula (II), R ³ is a fluorine atom, a carbon number An alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV)), or the formula (III R ² is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a group represented by the general formula (II) (in the general formula (II), R ³ is a fluorine atom) Or an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a group represented by the formula (IV)). A combination which is a group represented by the formula (III).
As a more preferable combination of R ¹ and R ² in the general formula (I), R ¹ is a group represented by the general formula (II) (in the general formula (II), R ³ is a fluorine atom, a methyl group) , An ethyl group, a methoxy group, an ethoxy group, or a group represented by the formula (IV)) or a group represented by the formula (III), and R ² is a hydrogen atom or a methyl group It is a certain combination.
As a particularly preferred combination of R ¹ and R ^{2 in} the general formula (I), in the general formula (I), R ¹ is a group represented by the formula (III), and R ² is a hydrogen atom. Combination (most preferably 1,2: 3,4-di-O-sulfanyl-meso-erythritol).

Examples of the cyclic sulfate compound in the present invention include 2,2-dioxo-1,3,2-dioxathiolane, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane, 4-ethyl-2, 2-dioxo-1,3,2-dioxathiolane, 4-propyl-2,2-dioxo-1,3,2-dioxathiolane, 4-butyl-2,2-dioxo-1,3,2-dioxathiolane, catechol sulfate , 1,2-cyclohexyl sulfate, and compounds represented by the following exemplified compounds 1 to 30.
However, the cyclic sulfate compound represented by the general formula (I) is not limited thereto.
In the structures of the following exemplary compounds, “Me” represents a methyl group, “Et” represents an ethyl group, “Pr” represents a propyl group, “iPr” represents an isopropyl group, “Bu” represents a butyl group, and “tBu” Is a tertiary butyl group, “Pent” is a pentyl group, “Hex” is a hexyl group, “OMe” is a methoxy group, “OEt” is an ethoxy group, “OPr” is a propoxy group, “OBu” Represents a butoxy group, “OPent” represents a pentyloxy group, and “OHex” represents a hexyloxy group. Further, the “wavy line” in R ^{1 to} R ³ represents a coupling position.
In some cases, stereoisomers derived from the substituents at the 4-position and 5-position of the 2,2-dioxo-1,3,2-dioxathiolane ring may be formed, and both are compounds included in the present invention.
Further, among the sulfate ester compounds represented by the general formula (I), when two or more asymmetric carbons are present in the molecule, stereoisomers (diastereomers) exist, but are not particularly described. To the extent it is a mixture of the corresponding diastereomers.

  The cyclic sulfate compound represented by the general formula (I) is preferably 2,2-dioxo-1,3,2-dioxathiolane, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane. 4-ethyl-2,2-dioxo-1,3,2-dioxathiolane, 4-propyl-2,2-dioxo-1,3,2-dioxathiolane, catechol sulfate, exemplary compound 1, exemplary compound 2, exemplary compound 16, Exemplified Compound 22, Exemplified Compound 23, and Exemplified Compounds 24-28, particularly preferably 2,2-dioxo-1,3,2-dioxathiolane, 4-methyl-1,3,2-dioxathiolane, 4- Ethyl-1,3,2-dioxathiolane, 4-propyl-1,3,2-dioxathiolane, catechol sulfate, exemplary compound 1, exemplary compound Example Compound 16, an illustrative Compound 22.

[Unsaturated sultone compound]
The unsaturated sultone compound of the present invention is preferably a compound represented by the following general formula (V).

In the general formula ^(V), R 4 ~R ⁷ are each independently a hydrogen atom, an alkyl group having a halogen atom, or a carbon number 1 to 6, n is an integer of 0 to 3.
The alkyl group having 1 to 6 carbon atoms may be an alkyl group which may be substituted with a halogen atom.
In the general formula (V), examples of the “halogen atom” include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
As the halogen atom, a fluorine atom is preferable.

In the general formula (V), the “alkyl group having 1 to 6 carbon atoms” is a linear or branched alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, Isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, 2-methylbutyl, 1-methylpentyl, neopentyl, 1-ethylpropyl, hexyl, 3,3-dimethyl A specific example is a butyl group.
As a C1-C6 alkyl group, a C1-C3 alkyl group is more preferable.
In the general formula (V), the “alkyl group optionally containing a halogen atom having 1 to 6 carbon atoms” is a linear or branched alkyl halide group having 1 to 6 carbon atoms, Fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluorohexyl Specific examples include fluoroisopropyl group, perfluoroisobutyl group, chloromethyl group, chloroethyl group, chloropropyl group, bromomethyl group, bromoethyl group, bromopropyl group, methyl iodide group, ethyl iodide group, and propyl iodide group. It is done.
As the halogenated alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms is more preferable.

As a preferable combination of R ^{4 to} R ⁷ , R ⁴ is a hydrogen atom, a fluorine atom, or an alkyl group that may contain a fluorine atom having 1 to 2 carbon atoms, and R ⁵ is a hydrogen atom or a fluorine atom. Or an alkyl group having 1 to 2 carbon atoms, R ⁶ is a hydrogen atom, a fluorine atom, or an alkyl group that may contain a fluorine atom having 1 to 2 carbon atoms, and R ⁷ is a hydrogen atom, The combination which is a fluorine atom or the alkyl group which may contain the fluorine atom of 1-2 carbon atoms, and n is 1-3 is mentioned.
n is preferably 1 to 3, more preferably 1 to 2, and particularly preferably 1.

Specific examples of the unsaturated sultone compound represented by the general formula (V) include the following compounds.
However, the unsaturated sultone compound represented by the general formula (V) is not limited to the following compounds.

  Among these unsaturated sultone compounds, 1,3-prop-1-ene sultone represented by the following structure is particularly preferable.

[Total content of cyclic sulfate compound and unsaturated sultone compound]
The total content of the cyclic sulfate compound and the unsaturated sultone compound is preferably 0.01% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolyte. More preferably, it is 0.05 mass%-5 mass%, More preferably, it is 0.1 mass%-2 mass%.
In the nonaqueous electrolytic solution of the present invention, only at least one cyclic sulfate compound and at least one unsaturated sultone compound may be used, or two or more kinds may be used.
When the cyclic sulfate compound and the unsaturated sultone compound are included, the content ratio is not limited.

[Phosphazene compounds]
The phosphazene compound of the present invention is preferably a compound represented by the following general formula (VI).

In the general formula (VI), R ^{8 to} R ¹³ each independently represents at least one selected from a halogen atom, an alkyl group, an aryl group, an alkoxy group, and an aryloxy group.
The alkoxy group and the aryloxy group may be an alkoxy group or an aryloxy group which may be substituted with a halogen atom.
In addition, the alkoxy group which may be substituted with a halogen atom may be linear or branched.
R ^{8 to} R ¹³ are preferably a halogen atom, an alkoxy group, or an aryloxy group from the viewpoint of electrochemical stability. As the halogen atom, fluorine, chlorine and bromine are more preferable, and fluorine is most preferable from the viewpoint of electrochemical stability and flame retardancy. On the other hand, the number of carbon atoms of the alkyl group and aryl group is not particularly limited, but the alkoxy group is preferably 10 carbon atoms or less, more preferably 6 carbon atoms or less, from the viewpoint of flame retardancy. As for only the alkoxy group, it is more preferable that the number of carbon atoms is 3 or less.
Moreover, as an aryloxy group, 6-10 are preferable, and a phenoxy group is more preferable.

Specific examples of these alkoxy groups include methoxy group, fluoromethoxy group, difluoromethoxy group, trifluoromethoxy group, ethoxy group, 1-fluoroethoxy group, 2-fluoroethoxy group, 1,1-difluoroethoxy group, 1, 2-difluoroethoxy group, 2,2-difluoroethoxy group, 1,1,2-trifluoroethoxy group, 1,2,2-trifluoroethoxy group, 2,2,2-trifluoroethoxy group, 1,1 , 2,2-tetrafluoroethoxy group, 1,2,2,2-tetrafluoroethoxy group, pentafluoroethoxy group, propoxy group (n-propoxy group), 1-fluoropropoxy group, 2-fluoropropoxy group, 3 -Fluoropropoxy group, 1,1-difluoropropoxy group, 1,2-difluoropropoxy group, 1,3- Fluoropropoxy group, 2,2-difluoropropoxy group, 2,3-difluoropropoxy group, 3,3-difluoropropoxy group, 1,1,2-trifluoropropoxy group, 1,2,2-trifluoropropoxy group, 1,1,3-trifluoropropoxy group, 1,2,3-trifluoropropoxy group, 1,3,3-trifluoropropoxy group, 2,2,3-trifluoropropoxy group, 2,3,3- Trifluoropropoxy group, 3,3,3-trifluoropropoxy group, 1,1,2,2-tetrafluoropropoxy group, 1,1,2,3-tetrafluoropropoxy group, 1,1,3,3- Tetrafluoropropoxy group, 1,2,2,3-tetrafluoropropoxy group, 1,2,3,3-tetrafluoropropoxy group, 2,2,3,3-tetra Fluoropropoxy group, 2,3,3,3-tetrafluoropropoxy group, 1,1,2,2,3-pentafluoropropoxy group, 1,2,2,3,3-pentafluoropropoxy group, 1, 1,3,3,3-pentafluoropropoxy group, 1,2,3,3,3-pentafluoropropoxy group, 2,2,3,3,3-pentafluoropropoxy group, 1,1,2,2 , 3,3-hexafluoropropoxy group, 1,1,2,3,3,3-hexafluoropropoxy group, 1,2,2,3
3,3-hexafluoropropoxy group, heptafluoropropoxy group, 1-methylethoxy group (i-propoxy group), 1-fluoro-1-methylethoxy group, 2-fluoro-1-methylethoxy group, 1,2- Difluoro-1-methylethoxy group, 1,2-difluoro-1- (fluoromethyl) ethoxy group, 1,2,2-trifluoro-1-methylethoxy group, 2,2,2-trifluoro-1-methyl Ethoxy group, 2,2, -difluoro-1- (fluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro-1-methylethoxy group, 1,2,2-trifluoro-1- (fluoromethyl) ) Ethoxy group, 2,2,2-trifluoro-1- (fluoromethyl) ethoxy group, 2,2-difluoro-1- (difluoromethyl) ethoxy group, 1,2,2 2-tetrafluoro-1- (fluoromethyl) ethoxy group, 1,2,2-trifluoro-1- (difluoromethyl) ethoxy group, 2,2,2-trifluoro-1- (difluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro-1- (difluoromethyl) ethoxy group, 2,2,2-trifluoro-1- (trifluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro- 1- (trifluoromethyl) ethoxy group and the like can be mentioned.

  As specific examples of the aryloxy group, an unsubstituted or fluorine-substituted phenoxy group is preferable. Specifically, a phenoxy group, a 2-fluorophenoxy group, a 3-fluorophenoxy group, a 4-fluorophenoxy group, 2, 3 -Difluorophenoxy group, 2,4-difluorophenoxy group, 2,5-difluorophenoxy group, 2,6-difluorophenoxy group, 3,4-difluorophenoxy group, 3,5-difluorophenoxy group, 2,3,4 -Trifluorophenoxy group, 2,3,5-trifluorophenoxy group, 2,3,6-trifluorophenoxy group, 2,4,5-trifluorophenoxy group, 2,4,6-trifluorophenoxy group, 3,4,5-trifluorophenoxy group, 2,3,4,5-tetrafluorophenoxy group, 2,3,4, - tetra-fluorophenoxy group, 2,3,5,6-fluorophenoxy group, pentafluorophenoxy group, and the like.

  Among these, for ease of production, methoxy group, trifluoromethoxy group, ethoxy group, 2,2,2-trifluoroethoxy group, propoxy group, 1-methylethoxy group (i-propoxy group), phenoxy group are More preferred are methoxy group, ethoxy group and phenoxy group.

In general formula (VI), one to three of R ^{8 to} R ¹³ are an alkoxy group or an aryloxy group, and the rest are halogen atoms, or all of R ^{8 to} R ¹³ are halogen. A form that is an atom is preferred.

Specific examples of the phosphazene compound represented by the general formula (VI) include the following compounds.
However, the unsaturated sultone compound represented by the general formula (VI) is not limited to the following compounds.

  Of these unsaturated phosphazene compounds, compounds represented by the following structures are preferred.

[Halogenated Phosphate Ester Compound]
The halogenated phosphate compound of the present invention is preferably a compound represented by the following general formula (VII).

In general formula (VII), R ^{14 to} R ¹⁶ each independently represents at least one selected from an alkyl group substituted with a halogen atom and an aryl group substituted with a halogen atom.
The alkyl group substituted with a halogen atom is preferably an alkyl group substituted with a fluorine atom. Specific examples include, for example, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 1-fluoroethyl group, 2- Fluoroethyl group, 1,1-difluoroethyl group, 1,2-difluoroethyl group, 2,2-difluoroethyl group, 1,1,2-trifluoroethyl group, 1,2,2-trifluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, 1,2,2,2-tetrafluoroethyl group, pentafluoroethyl group, 1-fluoropropyl group, 2- Fluoropropyl group, 3-fluoropropyl group, 1,1-difluoropropyl group, 1,2-difluoropropyl group, 1,3-difluoropropyl group 2,2-difluoropropyl group, 2,3-difluoropropyl group, 3,3-difluoropropyl group, 1,1,2-trifluoropropyl group, 1,2,2-trifluoropropyl group, 1,1 , 3-trifluoropropyl group, 1,2,3-trifluoropropyl group, 1,3,3-trifluoropropyl group, 2,2,3-trifluoropropyl group, 2,3,3-trifluoropropo Pill group, 3,3,3-trifluoropropyl group, 1,1,2,2-tetrafluoropropyl group, 1,1,2,3-tetrafluoropropyl group, 1,1,3,3-tetrafluoro Propyl group, 1,2,2,3-tetrafluoropropyl group, 1,2,3,3-tetrafluoropropyl group, 2,2,3,3-tetrafluoropropyl group, 2,3,3,3- Tetrafluoro Propyl group, 1,1,2,2,3-pentafluoropropyl group, 1,2,2,3,3-pentafluoropropyl group, 1,1,3,3,3-pentafluoropropyl group, 1, 2,3,3,3-pentafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,2,2,3,3-hexafluoropropyl group, 1,1,2 , 3,3,3-hexafluoropropyl group, 1,2,2,3,3,3-hexafluoropropyl group, heptafluoropropyl group, and the like.

The aryl group substituted with a halogen atom is preferably an aryl group substituted with a fluorine atom. Specific examples thereof include, for example, 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2,3 -Difluorophenyl group, 2,4-difluorophenyl group, 2,5-difluorophenyl group, 2,6-difluorophenyl group, 3,4-difluorophenyl group, 3,5-difluorophenyl group, 2,3,4 -Trifluorophenyl group, 2,3,5-trifluorophenyl group, 2,3,6-trifluorophenyl group, 2,4,5-trifluorophenyl group, 2,4,6-trifluorophenyl group, 3,4,5-trifluorophenyl group, 2,3,4,5-tetrafluorophenyl group, 2,3,4,6-tetrafluorophenyl group, 2 3,5,6-tetrafluorophenyl group, pentafluorophenyl group and the like.
Among these, 2,2,2-trifluoroethyl group is preferable.

[Total content of phosphazene compound and halogenated phosphate compound]
The total content of the phosphazene compound and the halogenated phosphate ester compound is preferably 0.01% by mass to 30% by mass with respect to the total amount of the non-aqueous electrolyte. More preferably, it is 0.05 mass%-10 mass%, Most preferably, it is 0.1 mass%-5 mass%.
The phosphazene compound and the halogenated phosphoric ester compound may be used alone or in combination of any two or more in any ratio.
When the phosphazene compound and the halogenated phosphate compound are included, the content ratio is not limited.
When the total content of the phosphazene compound and the halogenated phosphoric acid ester compound is added to 5% or more of the total amount of the non-aqueous electrolyte, flame retardancy can be further imparted to the non-aqueous electrolyte.

[Compound represented by formula (VIII)]
In the present invention, a nonaqueous electrolytic solution containing at least one selected from a cyclic sulfate ester compound and an unsaturated sultone compound, and at least one selected from a phosphazene compound and a halogenated phosphate ester compound, A compound represented by the general formula (VIII) can be added.
By adding the compound represented by the general formula (VIII), the low temperature performance of the battery can be further improved.

In general formula (VIII), M represents an alkali metal, Y represents a transition element, or a group 13, 14 or 15 element of the periodic table, b is an integer of 1 to 3, m is 1 to An integer of 4, n is an integer of 0 to 8, and q is 0 or 1. R ¹⁷ is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a hetero atom, and when q is 1 and m is 2 to 4, m R ¹⁷ may be bonded to each other). ¹⁸ is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (these groups are In the structure, a substituent or a hetero atom may be contained, and when n is 2 to 8, n R ^{18 s} may be bonded to each other to form a ring), or It represents a -Q ³ R ^19. Q ¹ , Q ² and Q ³ each independently represent O, S or NR ²⁰ , and R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 1 to 1 carbon atoms A halogenated alkyl group having 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a hetero atom in the structure; ^{And a} plurality of ¹⁹ or R ²⁰ may be bonded to each other to form a ring).

  In the electrolyte compound represented by the general formula (VIII), M is an alkali metal, and Y is a transition metal or a group 13, 14 or 15 element of the periodic table. Y is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb. Al, B, or P is more preferable. When Y is Al, B or P, the synthesis of the anionic compound becomes relatively easy, and the production cost can be suppressed. B representing the valence of the anion and the number of cations is an integer of 1 to 3, and is preferably 1. When b is larger than 3, the salt of the anionic compound tends to be difficult to dissolve in the mixed organic solvent, which is not preferable. The constants m and n are values related to the number of ligands and are determined by the type of M. m is an integer of 1 to 4, and n is an integer of 0 to 8. The constant q is 0 or 1. When q is 0, the chelating ring is a five-membered ring, and when q is 1, the chelating ring is a six-membered ring.

R ¹⁷ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene group, halogenated alkylene group, arylene group or halogenated arylene group may contain a substituent or a hetero atom in the structure. Specifically, instead of hydrogen atoms of these groups, halogen atoms, chain or cyclic alkyl groups, aryl groups, alkenyl groups, alkoxy groups, aryloxy groups, sulfonyl groups, amino groups, cyano groups, carbonyl groups, An acyl group, an amide group, or a hydroxyl group may be contained as a substituent. Moreover, the structure into which the nitrogen atom, the sulfur atom, or the oxygen atom was introduce | transduced instead of the carbon element of these groups may be sufficient. When q is 1 and m is 2 to 4, m R ^17s may be bonded to each other. Examples thereof include a ligand such as ethylenediaminetetraacetic acid.

R ¹⁸ is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or -Q ^3. R ¹⁹ (Q ³ and R ¹⁹ will be described later).
These alkyl group in R ^18, halogenated alkyl group, an aryl group or a halogenated aryl group, like R ^17, substituent in the structure may contain a hetero atom, also, n is 2 In the case of 8, n R ^{18 s} may be bonded to each other to form a ring. R ¹⁵ is preferably an electron-withdrawing group, particularly preferably a fluorine atom.

Q ¹ , Q ² and Q ³ each independently represents O, S or NR ²⁰ . That is, the ligand is bonded to Y through these heteroatoms.

R ¹⁶ and R ¹⁷ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 to 20 carbon atoms. Represents a halogenated aryl group. These alkyl group, halogenated alkyl group, aryl group, or halogenated aryl group may contain a substituent or a hetero atom in the structure thereof, as in R ¹⁷ . In addition, when there are a plurality of R ¹⁹ and R ²⁰ , each may be bonded to form a ring.

Examples of the alkali metal in M include lithium, sodium, potassium and the like. Of these, lithium is particularly preferred.
n is preferably an integer of 0 to 4.

When the nonaqueous electrolytic solution of the present invention contains an electrolyte compound represented by the general formula (VIII), the nonaqueous electrolytic solution of the present invention may contain only one compound represented by the general formula (VIII). Two or more kinds may be included.
Further, the electrolyte compound represented by the general formula (VIII) includes a compound represented by the following general formula (VIII-1), a compound represented by the following general formula (VIII-2), and the following general formula (VIII-3). And at least one compound selected from the group consisting of compounds represented by the following general formula (VIII-4). In the compounds represented by the general formulas (VIII-1) to (VIII-4), a compound in which M is lithium, sodium, or potassium is given as a more preferable compound of the electrolyte compound represented by the general formula (VIII). Particularly preferred is a compound in which M is lithium in the general formula (VIII-3).

  In general formulas (VIII-1) to (VIII-4), M has the same meaning as M in general formula (VIII).

[Compound represented by the general formula (IX)]
In the present invention, a nonaqueous electrolytic solution containing at least one selected from a cyclic sulfate ester compound and an unsaturated sultone compound, and at least one selected from a phosphazene compound and a halogenated phosphate ester compound, A compound represented by the general formula (IX) can be added.
By adding the compound represented by the general formula (IX), the low temperature performance of the battery can be further improved by improving the ionic conductivity of the film.

In general formula (IX), X represents an alkali metal or a hydrocarbon group having 1 to 12 carbon atoms.
Examples of the alkali metal include lithium, sodium, potassium and the like. Of these, lithium is particularly preferred.
Examples of the hydrocarbon group having 1 to 12 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group, cyclohexyl group, vinyl group, allyl group, A butenyl group, a phenyl group, a naphthyl group, a biphenyl group, etc. are mentioned.
The hydrocarbon group having 1 to 12 carbon atoms is preferably a methyl group, an ethyl group, a propyl group, or a phenyl group.
Moreover, the C1-C12 hydrocarbon group may be substituted with a halogen atom or a hetero atom (preferably an alkoxy group or an aryloxy group).
Examples of the hydrocarbon group having 1 to 12 carbon atoms substituted by a halogen atom or a hetero atom (preferably an alkoxy group or an aryloxy group) include, for example, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, 2, 2,2-trifluoroethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, perfluorooctyl group, perfluorononyl group, perfluorononyl group Fluorodecyl group, perfluoroundecanyl group, perfluorododecanyl group, perfluoroisopropyl group, perfluoroisobutyl group, 1,1,1,3,3,3-hexafluoropropan-2-yl group, methoxyethyl Group, ethoxyethyl group, propoxyethyl group, pheno Shiechiru group, methoxypropyl group, ethoxypropyl group, and the like phenoxypropyl group.
The hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a hetero atom (preferably an alkoxy group or an aryloxy group) is preferably a 2,2,2-trifluoroethyl group. .
The compound of the general formula (IX) is preferably lithium difluorophosphate, methyl difluorophosphate, ethyl difluorophosphate, propyl difluorophosphate, phenyl difluorophosphate, 2,2,2-trifluoroethyl difluorophosphate. More preferred is lithium difluorophosphate.

[Compound represented by formula (X)]
In the present invention, a nonaqueous electrolytic solution containing at least one selected from a cyclic sulfate ester compound and an unsaturated sultone compound, and at least one selected from a phosphazene compound and a halogenated phosphate ester compound, A compound represented by the general formula (X) can be added.
By adding the compound represented by the general formula (X), the life performance of the battery can be further improved due to the stabilization effect of the film.

In the general formula (X), R ²¹ and R ²² each independently represent a hydrogen atom, a methyl group, an ethyl group, or a propyl group.

  The compound represented by the general formula (X) is preferably vinylene carbonate.

[Compound represented by formula (XI)]
In the present invention, a nonaqueous electrolytic solution containing at least one selected from a cyclic sulfate ester compound and an unsaturated sultone compound, and at least one selected from a phosphazene compound and a halogenated phosphate ester compound, A compound represented by the general formula (XI) can be added.
By adding the compound represented by the general formula (XI), the life performance of the battery can be further improved due to the stabilization effect of the film.

In general formula (XI), R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are each independently a hydrocarbon group having 1 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms which may be substituted with a fluorine atom. Represents an aryl group having 6 to 12 carbon atoms, a hydrogen atom, a fluorine atom, or a chlorine atom. However, R ^{23 to} R ²⁶ are not simultaneously hydrogen atoms.

In general formula (XI), examples of the alkyl group having 1 to 3 carbon atoms which may be substituted with a fluorine atom in R ^{23 to} R ²⁶ include, for example, fluoromethyl, difluoromethyl, trifluoromethyl, pentafluoroethyl, hepta And fluoropropyl.

  Specific examples of the compound represented by the general formula (XI) include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-fluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoro. Examples thereof include fluorinated ethylene carbonates such as ethylene carbonate, 4,4,5-trifluoroethylene carbonate, 4,4,5,5-tetrafluoroethylene carbonate, etc., in which 1 to 4 hydrogen atoms are substituted by fluorine in ethylene carbonate. It is done. Among these, vinyl ethylene carbonate, 4,5-divinylethylene carbonate, 4,5-difluoroethylene carbonate, and 4-fluoroethylene carbonate are preferable.

[Total content of compound represented by general formula (VIII), compound represented by general formula (IX), compound represented by general formula (X), and compound represented by general formula (XI)]
The compounds represented by the general formula (VIII) to the general formula (XI) may be used singly or in combinations of two or more in any ratio. The total content of the compounds represented by the general formulas (VIII) to (XI) is preferably 0.01% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolyte. More preferably, it is 0.05 mass%-5 mass%, More preferably, it is 0.1 mass%-2 mass%.
When the added amount is less than 0.01% by weight, the effect is hardly exhibited, and when it is 10% by weight or more, problems such as an increase in battery resistance occur.

  Next, other components of the nonaqueous electrolytic solution will be described. The nonaqueous electrolytic solution generally contains an electrolyte and a nonaqueous solvent.

[Nonaqueous solvent]
Various known solvents can be appropriately selected as the non-aqueous solvent according to the present invention, but it is preferable to use a cyclic aprotic solvent and / or a chain aprotic solvent.
In order to improve the safety of the battery, when aiming to improve the flash point of the solvent, it is preferable to use a cyclic aprotic solvent as the non-aqueous solvent.

[Cyclic aprotic solvent]
As the cyclic aprotic solvent, cyclic carbonate, cyclic carboxylic acid ester, cyclic sulfone, and cyclic ether can be used.
The cyclic aprotic solvent may be used alone or in combination of two or more.
The mixing ratio of the cyclic aprotic solvent in the non-aqueous solvent is 10% by mass to 100% by mass, more preferably 20% by mass to 90% by mass, and particularly preferably 30% by mass to 80% by mass. By setting it as such a ratio, the electroconductivity of the electrolyte solution relating to the charge / discharge characteristics of the battery can be increased.
Specific examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and the like. Of these, ethylene carbonate and propylene carbonate having a high dielectric constant are preferably used. In the case of a battery using graphite as the negative electrode active material, ethylene carbonate is more preferable. Moreover, you may use these cyclic carbonates in mixture of 2 or more types.

Specific examples of the cyclic carboxylic acid ester include γ-butyrolactone, δ-valerolactone, alkyl substitution products such as methyl γ-butyrolactone, ethyl γ-butyrolactone, and ethyl δ-valerolactone.
The cyclic carboxylic acid ester has a low vapor pressure, a low viscosity, a high dielectric constant, and can lower the viscosity of the electrolytic solution without lowering the degree of dissociation between the flash point of the electrolytic solution and the electrolyte. For this reason, since it has the feature that the conductivity of the electrolytic solution, which is an index related to the discharge characteristics of the battery, can be increased without increasing the flammability of the electrolytic solution, when aiming to improve the flash point of the solvent, It is preferable to use a cyclic carboxylic acid ester as the cyclic aprotic solvent. Of the cyclic carboxylic acid esters, γ-butyrolactone is most preferred.
The cyclic carboxylic acid ester is preferably used by mixing with another cyclic aprotic solvent. For example, a mixture of a cyclic carboxylic acid ester and a cyclic carbonate and / or a chain carbonate can be mentioned.

Examples of the cyclic sulfone include sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethyl sulfone, diethyl sulfone, dipropyl sulfone, methylethyl sulfone, methylpropyl sulfone and the like.
An example of a cyclic ether is dioxolane.

[Chain aprotic solvent]
As the chain aprotic solvent of the present invention, a chain carbonate, a chain carboxylic acid ester, a chain ether, a chain phosphate, or the like can be used.
The mixing ratio of the chain aprotic solvent in the non-aqueous solvent is 10% by mass to 100% by mass, more preferably 20% by mass to 90% by mass, and particularly preferably 30% by mass to 80% by mass.
Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, dibutyl carbonate, methyl pentyl carbonate, Examples include ethyl pentyl carbonate, dipentyl carbonate, methyl heptyl carbonate, ethyl heptyl carbonate, diheptyl carbonate, methyl hexyl carbonate, ethyl hexyl carbonate, dihexyl carbonate, methyl octyl carbonate, ethyl octyl carbonate, dioctyl carbonate, and methyltrifluoroethyl carbonate. These chain carbonates may be used as a mixture of two or more.

Specific examples of the chain carboxylic acid ester include methyl pivalate.
Specific examples of the chain ether include dimethoxyethane.
Specific examples of the chain phosphate ester include trimethyl phosphate.

[Combination of solvents]
The non-aqueous solvent used in the non-aqueous electrolyte solution according to the present invention may be used alone or in combination. Further, only one or more types of cyclic aprotic solvents may be used, or only one or more types of chain aprotic solvents may be used, or cyclic aprotic solvents and chain proticity may be used. You may mix and use a solvent. When the load characteristics and low temperature characteristics of the battery are particularly intended to be improved, it is preferable to use a combination of a cyclic aprotic solvent and a chain aprotic solvent as the nonaqueous solvent.
Furthermore, in view of the electrochemical stability of the electrolytic solution, it is most preferable to apply a cyclic carbonate to the cyclic aprotic solvent and a chain carbonate to the chain aprotic solvent. Further, the conductivity of the electrolytic solution related to the charge / discharge characteristics of the battery can be increased by a combination of the cyclic carboxylic acid ester and the cyclic carbonate and / or the chain carbonate.

As a combination of cyclic carbonate and chain carbonate, specifically, ethylene carbonate and dimethyl carbonate, ethylene carbonate and methyl ethyl carbonate, ethylene carbonate and diethyl carbonate, propylene carbonate and dimethyl carbonate, propylene carbonate and methyl ethyl carbonate, propylene carbonate and Diethyl carbonate, ethylene carbonate and propylene carbonate and methyl ethyl carbonate, ethylene carbonate and propylene carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and methyl ethyl carbonate Diethyl carbonate, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate, ethylene carbonate, propylene carbonate and methyl ethyl carbonate And diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate.
The mixing ratio of the cyclic carbonate and the chain carbonate is expressed as a mass ratio, and the cyclic carbonate: chain carbonate is 5:95 to 80 to 20, more preferably 10:90 to 70:30, particularly preferably 15:85. ~ 55: 45. By setting it as such a ratio, since the raise of the viscosity of electrolyte solution can be suppressed and the dissociation degree of electrolyte can be raised, the conductivity of electrolyte solution in connection with the charge / discharge characteristic of a battery can be raised. In addition, the solubility of the electrolyte can be further increased. Therefore, since it can be set as the electrolyte solution excellent in the electrical conductivity in normal temperature or low temperature, the load characteristic of the battery from normal temperature to low temperature can be improved.

  Specific examples of combinations of cyclic carboxylic acid esters and cyclic carbonates and / or chain carbonates include γ-butyrolactone and ethylene carbonate, γ-butyrolactone and ethylene carbonate and dimethyl carbonate, and γ-butyrolactone and ethylene carbonate and methylethyl. Carbonate, γ-butyrolactone and ethylene carbonate and diethyl carbonate, γ-butyrolactone and propylene carbonate, γ-butyrolactone and propylene carbonate and dimethyl carbonate, γ-butyrolactone and propylene carbonate and methyl ethyl carbonate, γ-butyrolactone and propylene carbonate and diethyl carbonate, γ-butyrolactone, ethylene carbonate, propylene carbonate, γ-butyrolactone, Tylene carbonate and propylene carbonate and dimethyl carbonate, γ-butyrolactone and ethylene carbonate, propylene carbonate and methyl ethyl carbonate, γ-butyrolactone, ethylene carbonate, propylene carbonate and diethyl carbonate, γ-butyrolactone, ethylene carbonate, dimethyl carbonate and methyl ethyl carbonate, γ-butyrolactone, ethylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, γ-butyrolactone, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, γ-butyrolactone, ethylene carbonate And professional Ren carbonate, dimethyl carbonate and methyl ethyl carbonate, γ-butyrolactone, ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate, γ-butyrolactone, ethylene carbonate, propylene carbonate, methyl ethyl carbonate and diethyl carbonate, γ-butyrolactone and ethylene carbonate Propylene carbonate, dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate, γ-butyrolactone and sulfolane, γ-butyrolactone and ethylene carbonate and sulfolane, γ-butyrolactone and propylene carbonate and sulfolane, γ-butyrolactone, ethylene carbonate, propylene carbonate and sulfolane, γ -Butyrolactone and sul Such as orchids and dimethyl carbonate.

[Other solvents]
The nonaqueous electrolytic solution according to the present invention may contain a solvent other than the above as a nonaqueous solvent. Specific examples of the other solvent include amides such as dimethylformamide, chain carbamates such as methyl-N, N-dimethylcarbamate, cyclic amides such as N-methylpyrrolidone, N, N-dimethylimidazolidinone and the like. Examples thereof include boron compounds such as cyclic urea, trimethyl borate, triethyl borate, tributyl borate, trioctyl borate, trimethylsilyl borate, and polyethylene glycol derivatives represented by the following general formula.
HO (CH ₂ CH ₂ O) _a H
HO [CH ₂ CH (CH ₃ ) O] _b H
CH ₃ O (CH ₂ CH ₂ O) _c H
CH ₃ O [CH ₂ CH (CH ₃ ) O] _d H
CH ₃ O (CH ₂ CH ₂ O) _e CH ₃
CH ₃ O [CH ₂ CH (CH ₃ ) O] _f CH _{3
C 9 H 19 PHO (CH 2} CH 2 O) g [CH (CH 3) O] h CH 3
(Ph is a phenyl group)
CH ₃ O [CH ₂ CH (CH ₃ ) O] _i CO [OCH (CH ₃ ) CH ₂ ] _j OCH ₃
In the above formula, a to f are integers of 5 to 250, g to j are integers of 2 to 249, 5 ≦ g + h ≦ 250, and 5 ≦ i + j ≦ 250.

〔Electrolytes〕
Various known electrolytes can be used for the nonaqueous electrolytic solution of the present invention, and any of them can be used as long as it is normally used as an electrolyte for a nonaqueous electrolytic solution.
Specific examples of the electrolyte in the nonaqueous electrolytic solution of the present invention include (C ₂ H ₅ ) ₄ NPF ₆ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NClO ₄ , and (C ₂ H ₅ ) ₄ NAsF ₆ , (C ₂ H ₅ ) ₄ N ₂ SiF ₆ , (C ₂ H ₅ ) ₄ NOSO ₂ C _k F _{(2k + 1)} (k = 1 to 8), (C ₂ H ₅ ) ₄ NPF _{n [C k F (2k +} 1)] (6-n) (n = 1~5, k = 1~8 integer) tetraalkylammonium salts, such _{as, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, Li 2 SiF ₆ , LiOSO ₂ C _k F _{(2k + 1)} (k = 1 to 8), LiPF _n [C _k F _{(2k + 1)} ] _(6-n) (n = 1 to 5, k = 1 to 8 ₎ ) And the like. Moreover, the lithium salt represented by the following general formula can also be used.

_{^{LiC (SO 2 R 27) (}} SO 2 R 28) (SO 2 R 29), LiN (SO 2 OR 30) (SO 2 OR 31), LiN (SO 2 R 32) (SO 2 R 33) ( where R ^{27 to} R ³³ may be the same as or different from each other, and are a C 1-8 perfluoroalkyl group). These electrolytes may be used alone or in combination of two or more.
Of these, lithium salts are particularly desirable, and LiPF ₆ , LiBF ₄ , LiOSO ₂ C _k F _{(2k + 1)} (k = 1 to 8), LiClO ₄ , LiAsF ₆ , LiNSO ₂ [C _k F _{( 2k + 1)] 2 (k} = 1~8 _{integer), LiPF n [C k F} (2k + 1)] (6-n) (n = 1~5, k = 1~8 integer) are preferred.
The electrolyte according to the present invention is usually preferably contained in the nonaqueous electrolyte at a concentration of 0.1 mol / L to 3 mol / L, preferably 0.5 mol / L to 2 mol / L.

In the nonaqueous electrolytic solution of the present invention, when a cyclic carboxylic acid ester such as γ-butyrolactone is used in combination as the nonaqueous solvent, it is particularly desirable to contain LiPF ₆ . Since LiPF ₆ has a high degree of dissociation, the conductivity of the electrolytic solution can be increased, and the reductive decomposition reaction of the electrolytic solution on the negative electrode can be suppressed. LiPF ₆ may be used alone, or LiPF ₆ and other electrolytes may be used. Any other electrolyte can be used as long as it is normally used as an electrolyte for a non-aqueous electrolyte, but lithium salts other than LiPF ₆ are preferred among the specific examples of the lithium salts described above. .
Specific examples include LiPF ₆ and LiBF ₄ , LiPF ₆ and LiN [SO ₂ C _k F _{(2k + 1)} ] ₂ (k = 1 to 8), LiPF ₆ , LiBF ₄ and LiN [SO ₂ C _k F _{( 2k + 1)} ] (k = 1 to 8).

The ratio of LiPF _{6 in} the lithium salt is 1% by mass to 100% by mass, preferably 10% by mass to 100% by mass, and more preferably 50% by mass to 100% by mass. Such an electrolyte is preferably contained in the nonaqueous electrolytic solution at a concentration of 0.1 mol / L to 3 mol / L, preferably 0.5 mol / L to 2 mol / L.
The non-aqueous electrolyte of the present invention is not only suitable as a non-aqueous electrolyte for a lithium secondary battery, but also a non-aqueous electrolyte for a primary battery, a non-aqueous electrolyte for an electrochemical capacitor, and an electric double layer capacitor. It can also be used as an electrolytic solution for aluminum electrolytic capacitors.

<Lithium secondary battery>
The lithium secondary battery of the present invention basically comprises a negative electrode, a positive electrode, and the non-aqueous electrolyte of the present invention, and a separator is usually provided between the negative electrode and the positive electrode. .

(Negative electrode)
The negative electrode active material constituting the negative electrode is metal lithium, a lithium-containing alloy, a metal or alloy that can be alloyed with lithium, an oxide that can be doped / undoped with lithium ions, and a lithium ion doped / undoped At least one selected from possible transition metal nitrides and carbon materials capable of doping and dedoping lithium ions (may be used alone or a mixture containing two or more of these may be used. ) Can be used.
Examples of metals or alloys that can be alloyed with lithium (or lithium ions) include silicon, silicon alloys, tin, and tin alloys. Further, lithium titanate may be used.
Among these, carbon materials that can be doped / undoped with lithium ions are preferable. Examples of such carbon materials include carbon black, activated carbon, graphite materials (artificial graphite, natural graphite), amorphous carbon materials, and the like. The form of the carbon material may be any of a fibrous form, a spherical form, a potato form, and a flake form.

Specific examples of the amorphous carbon material include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1500 ° C. or less, and mesopause bitch carbon fiber (MCF).
Examples of the graphite material include natural graphite and artificial graphite. As artificial graphite, graphitized MCMB, graphitized MCF, and the like are used. Further, as the graphite material, a material containing boron can be used. As the graphite material, those coated with a metal such as gold, platinum, silver, copper and tin, those coated with amorphous carbon, and those obtained by mixing amorphous carbon and graphite can be used.

These carbon materials may be used alone or in combination of two or more.
As the carbon material, a carbon material having a (002) plane distance d (002) of 0.340 nm or less measured by X-ray analysis is particularly preferable. Further, as the carbon material, graphite having a true density of 1.70 g / cm ³ or more or a highly crystalline carbon material having properties close thereto is also preferable. When the carbon material as described above is used, the energy density of the battery can be further increased.

(Positive electrode)
As the positive electrode active material constituting the positive electrode, transition metal oxides or transition metal sulfides such as MoS ₂ , TiS ₂ , MnO ₂ , V ₂ O ₅ , LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _X Co _(1-X) O ₂ [0 <X <1], composite oxide composed of lithium and transition metal such as LiFePO ₄ , polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene, dimercaptothiadiazole, polyaniline complex Examples thereof include conductive polymer materials. Among these, a composite oxide composed of lithium and a transition metal is particularly preferable. When the negative electrode is lithium metal or a lithium alloy, a carbon material can be used as the positive electrode. In addition, a mixture of a composite oxide of lithium and a transition metal and a carbon material can be used as the positive electrode.
Said positive electrode active material may be used by 1 type, and may mix and use 2 or more types. When the positive electrode active material has insufficient conductivity, it can be used together with a conductive auxiliary agent to constitute a positive electrode. Examples of the conductive assistant include carbon materials such as carbon black, amorphous whiskers, and graphite.

(Separator)
The separator is a film that electrically insulates the positive electrode and the negative electrode and transmits lithium ions, and examples thereof include a porous film and a polymer electrolyte.
A microporous polymer film is preferably used as the porous film, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, and polyester.
In particular, porous polyolefin is preferable. Specifically, a porous polyethylene film, a porous polypropylene film, or a multilayer film of a porous polyethylene film and a polypropylene film can be exemplified. On the porous polyolefin film, other resin excellent in thermal stability may be coated.
Examples of the polymer electrolyte include a polymer in which a lithium salt is dissolved, a polymer swollen with an electrolytic solution, and the like.
The nonaqueous electrolytic solution of the present invention may be used for the purpose of obtaining a polymer electrolyte by swelling a polymer.

(Battery configuration)
The lithium secondary battery of this invention contains the said negative electrode active material, a positive electrode active material, and a separator. The lithium secondary battery of the present invention can take various known shapes, and can be formed into a cylindrical shape, a coin shape, a square shape, a film shape, or any other shape. However, the basic structure of the battery is the same regardless of the shape, and the design can be changed according to the purpose.
As an example of the lithium secondary battery (nonaqueous electrolyte secondary battery) of the present invention, a coin-type battery shown in FIG.
In the coin-type battery shown in FIG. 1, a disc-shaped negative electrode 2, a separator 5 into which a non-aqueous electrolyte solution obtained by dissolving an electrolyte in a non-aqueous solvent, a disc-shaped positive electrode 1, stainless steel, or aluminum as necessary Spacer plates 7 and 8 are stacked in this order and accommodated between positive electrode can 3 (hereinafter also referred to as “battery can”) and sealing plate 4 (hereinafter also referred to as “battery can lid”). The The positive electrode can 3 and the sealing plate 4 are caulked and sealed via a gasket 6.

The lithium secondary battery of the present invention is obtained by charging / discharging a lithium secondary battery (lithium secondary battery before charge / discharge) including a negative electrode, a positive electrode, and the non-aqueous electrolyte of the present invention. A lithium secondary battery may also be used.
That is, the lithium secondary battery of the present invention is prepared by first preparing a lithium secondary battery before charge / discharge including a negative electrode, a positive electrode, and the non-aqueous electrolyte of the present invention, and then before the charge / discharge. It may be a lithium secondary battery (charged / discharged lithium secondary battery) produced by charging / discharging the lithium secondary battery one or more times.

  The use of the non-aqueous electrolyte of the embodiment of the present invention and the lithium secondary battery using the non-aqueous electrolyte is not particularly limited, and can be used for various known uses. For example, notebook computers, mobile computers, mobile phones, headphone stereos, video movies, LCD TVs, handy cleaners, electronic notebooks, calculators, radios, backup power applications, motors, automobiles, electric cars, motorcycles, electric bikes, bicycles, electric bicycles It can be widely used regardless of whether it is a small portable device or a large device, such as a lighting fixture, a game machine, a watch, a power tool, a camera.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In the following examples, “wt%” represents mass%.

[Example 1]
A lithium secondary battery was produced by the following procedure.
<Production of negative electrode>
20 parts by mass of artificial graphite, 80 parts by mass of natural graphite, 1 part by mass of carboxymethyl cellulose and 2 parts by mass of SBR latex were kneaded with an aqueous solvent to prepare a paste-like negative electrode mixture slurry.
Next, this negative electrode mixture slurry was applied to a negative electrode current collector made of a strip-shaped copper foil having a thickness of 18 μm, dried, and then compressed by a roll press to form a sheet-shaped negative electrode comprising a negative electrode current collector and a negative electrode active material layer Got. The coating density of the negative electrode active material layer at this time was 10 mg / cm ² , and the packing density was 1.5 g / ml.

<Preparation of positive electrode>
90 parts by mass of LiCoO ₂ , 5 parts by mass of acetylene black and 5 parts by mass of polyvinylidene fluoride were kneaded using N-methylpyrrolidinone as a solvent to prepare a paste-like positive electrode mixture slurry.
Next, this positive electrode mixture slurry is applied to a positive electrode current collector made of a strip-shaped aluminum foil having a thickness of 20 μm, dried, and then compressed by a roll press to form a sheet-like positive electrode comprising a positive electrode current collector and a positive electrode active material. Obtained. The coating density of the positive electrode active material layer at this time was 30 mg / cm ² , and the packing density was 2.5 g / ml.

<Preparation of non-aqueous electrolyte>
In a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) at a ratio of 1: 1: 1 (volume ratio) as a nonaqueous solvent, LiPF ₆ as an electrolyte was dissolved. The electrolyte concentration was adjusted to 1 mol / liter.
To the solution obtained above, 0.5 wt% of a cyclic sulfate compound [Exemplary Compound 1] and 0.5 wt% of a phosphazene compound [Compound P-1 below] are added as additives. An electrolytic solution was obtained.

<Production of coin-type battery>
The above-mentioned negative electrode was 14 mm in diameter and the above-mentioned positive electrode was 13 mm in diameter, and each was punched into a disk shape to obtain coin-shaped electrodes (negative electrode and positive electrode). Further, a microporous polyethylene film having a thickness of 20 μm was punched into a disk shape having a diameter of 17 mm to obtain a separator.
The obtained coin-shaped negative electrode, separator, and coin-shaped positive electrode are laminated in this order in a battery can (2032 size) made of stainless steel, and 20 μl of the non-aqueous electrolyte is injected to be contained in the separator, the positive electrode, and the negative electrode. Soaked.
Further, an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring are placed on the positive electrode, and the battery can be sealed by caulking the battery can lid through a polypropylene gasket, and the diameter is 20 mm and height. A coin-type lithium secondary battery (hereinafter referred to as a test battery) having the configuration shown in FIG.
Each measurement was implemented about the obtained coin-type battery (battery for a test).

[Evaluation method]
<Measurement of initial battery characteristics and resistance (-20 ° C.)>
The coin-type battery is charged at a constant voltage of 4.0 V, and then the charged coin-type battery is cooled to −20 ° C. in a thermostatic bath, and discharged at −20 ° C. with a constant current of 0.2 mA, and discharge starts. The direct current resistance [Ω] of the coin-type battery was measured by measuring the potential drop after 10 seconds. About the obtained initial resistance value, this resistance value when the initial resistance value of [Comparative Example 1] was set to 100 was obtained by the following equation.
The obtained results are shown in Table 1.

Initial characteristics, resistance value (-20 ℃)
= Initial resistance value [Ω] in Example 1 / Initial resistance value [Ω] × 100 [%] in Comparative Example 1

<Measurement of battery storage characteristics and capacity retention>
Furthermore, after charging with a constant voltage of 4.2 V and storing the charged coin-type battery in a constant temperature bath at 80 ° C. for 3 days (hereinafter, this operation is referred to as “high temperature storage test”), the same discharge capacity as the first time The discharge capacity [mAh] after the high-temperature storage test was measured by the method, and the capacity retention rate which is the storage characteristic of the battery was calculated by the following formula.
The obtained results are shown in Table 1.

Storage characteristics, capacity retention [%]
= Discharge capacity after high-temperature storage test [mAh] / 1st cycle discharge capacity [mAh] × 100

<Battery storage characteristics, resistance retention rate (−20 ° C.) measurement>
After the initial resistance measurement, the coin-type battery is charged with a constant voltage of 4.2 V, and the charged coin-type battery is stored in a constant temperature bath at 80 ° C. for 3 days (this operation is hereinafter referred to as “high temperature storage test”). The resistance value after the high temperature storage test was measured by the same method as the initial resistance value, and the resistance maintenance rate of the battery was calculated from the following equation.
The obtained results are shown in Table 1.

Storage characteristics, resistance retention (-20 ° C)
= (Resistance value [Ω] after high-temperature storage test in Example 1 / initial resistance value [Ω] in Example 1) / (resistance value [Ω] after high-temperature storage in Comparative Example 1 / Comparative Example 1 Initial resistance value at [Ω]

[Example 2]
A coin was prepared in the same manner as in Example 1 except that 0.5 wt% of the cyclic sulfate ester compound [Exemplary Compound 1] and 1.0 wt% of the phosphazene compound [Compound P-1] were used as additives for the nonaqueous electrolyte. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 3
A coin was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 1] and 1.0 wt% of the phosphazene compound [Compound P-1] were used as the additive for the nonaqueous electrolytic solution. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 4
A coin was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 1] and 5.0 wt% of the phosphazene compound [Compound P-1] were used as additives for the non-aqueous electrolyte. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 5
A coin-type battery was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 1] and 10.0 wt% of the phosphazene compound [Compound P-1] were used as the non-aqueous electrolyte. Created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 6
A coin was prepared in the same manner as in Example 1 except that 0.5 wt% of the cyclic sulfate ester compound [Exemplary Compound 22] and 0.5 wt% of the phosphazene compound [Compound P-1] were used as additives for the non-aqueous electrolyte. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 7
A coin was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 22] and 1.0 wt% of the phosphazene compound [Compound P-1] were used as additives for the non-aqueous electrolyte. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 8
A coin was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 22] and 5.0 wt% of the phosphazene compound [Compound P-1] were used as nonaqueous electrolyte additives. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 9
A coin was prepared in the same manner as in Example 1 except that 1.0 wt% of the cyclic sulfate compound [Exemplary Compound 22] and 10.0 wt% of the phosphazene compound [Compound P-1] were used as the additive for the non-aqueous electrolyte. A type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 10
Example 1 was used except that 1.0 wt% of a cyclic sulfate ester compound [Compound SA-1] and 1.0 wt% of a phosphazene compound [Compound P-1] were used as additives for the nonaqueous electrolyte. A coin-type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 11
Example 1 was used except that 1.0 wt% of a cyclic sulfate ester compound [compound SA-2] and 1.0 wt% of a phosphazene compound [compound P-1] were used as additives for the nonaqueous electrolytic solution. A coin-type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 12
As additives for the non-aqueous electrolyte, an unsaturated sultone compound [1,3-prop-1-ene sultone (compound PRS) below] 1.0 wt% and a phosphazene compound [compound P-1] 1.0 wt% were used. A coin-type battery was prepared in the same manner as in Example 1 except for the above. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 13
Example 1 was used except that 1.0 wt% of a cyclic sulfate ester compound [Exemplary Compound 22] and 1.0 wt% of a phosphazene compound [Compound P-2] were used as additives for the nonaqueous electrolytic solution. A coin-type battery was created. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 14
Example 1 except that 1.0 wt% of a cyclic sulfate ester compound [Exemplary Compound 22] and 1.0 wt% of a halogenated phosphate ester compound [Compound P-3] were used as additives for the non-aqueous electrolyte. A coin-type battery was prepared in the same manner. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 15
As additives of the non-aqueous electrolyte, cyclic sulfate compound [Exemplary Compound 1] 0.5 wt%, cyclic sulfate ester compound [Exemplary Compound 22] 0.5 wt%, and phosphazene compound [Compound P-1] 1.0 wt% A coin-type battery was prepared in the same manner as in Example 1 except that was used. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 16
As additive of non-aqueous electrolyte, cyclic sulfate compound [Exemplary Compound 22] 0.5 wt%, unsaturated sultone compound [PRS] 0.5 wt%, and phosphazene compound [Compound P-1] 1.0 wt% are used. A coin-type battery was produced in the same manner as in Example 1 except that. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 17
As an additive for the nonaqueous electrolytic solution, 1.0 wt% of a cyclic sulfate ester compound [Exemplary Compound 22], 1.0 wt% of a phosphazene compound [Compound P-1], and 1.0 wt% of LiFOP [the following compound] were used. A coin-type battery was prepared in the same manner as in Example 1 except for the above. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 18
As additives for the non-aqueous electrolyte, cyclic sulfate ester compound [Exemplary Compound 22] 1.0 wt%, phosphazene compound [Compound P-1] 1.0 wt%, and lithium difluorophosphate (following compound) 1.0 wt% A coin-type battery was produced in the same manner as in Example 1 except that and were used. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 19
As additives for the non-aqueous electrolyte, cyclic sulfate ester compound [Exemplary Compound 22] 1.0 wt%, phosphazene compound [Compound P-1] 1.0 wt%, and the following vinylene carbonate (the following compound) 1.0 wt%, A coin-type battery was produced in the same manner as in Example 1 except that it was used. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 20
As additives for the non-aqueous electrolyte, cyclic sulfate compound [Exemplary Compound 22] 1.0 wt%, phosphazene compound [Compound P-1] 1.0 wt%, and the following fluoroethylene carbonate (following compound) 1.0 wt%, A coin-type battery was prepared in the same manner as in Example 1 except that was used. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 1]
A coin-type battery was prepared in the same manner as in Example 1 except that no additive was used in the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 2]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 1] was used as the additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 3]
A coin-type battery was produced in the same manner as in Example 1 except that only 1.0 wt% of the cyclic sulfate ester compound [Exemplary Compound 22] was used as the additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 4]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the cyclic sulfate ester compound [Compound SA-1] was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 5]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the cyclic sulfate compound [Compound SA-2] was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 6]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of an unsaturated sultone compound [PRS] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 7]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the phosphazene compound [Compound P-1] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 8]
A coin-type battery was prepared in the same manner as in Example 1 except that only 5.0 wt% of the phosphazene compound [Compound P-1] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 9]
A coin-type battery was prepared in the same manner as in Example 1 except that only 10.0 wt% of the phosphazene compound [Compound P-1] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 10]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the phosphazene compound [Compound P-2] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 11]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of the phosphazene compound [Compound P-3] was used as an additive for the nonaqueous electrolytic solution. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 12]
A coin-type battery was prepared in the same manner as in Example 1 except that only LiFOP 1.0 wt% was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 13]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of lithium difluorophosphate was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 14]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of vinylene carbonate was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 15]
A coin-type battery was prepared in the same manner as in Example 1 except that only 1.0 wt% of fluoroethylene carbonate was used as an additive for the non-aqueous electrolyte. Each measurement was carried out on the obtained coin-type battery in the same manner as in Example 1. The evaluation results are shown in Table 2.

As shown in Examples 1 to 16 of Table 1, by adding at least one of a cyclic sulfate ester compound and an unsaturated sultone compound and at least one of a phosphazene compound and a halogenated phosphate ester compound, the cyclic sulfate ester Compared with the case where each of the compound and the unsaturated sultone compound is used alone, the low temperature discharge characteristics can be remarkably improved while improving the storage characteristics of the battery. When the compounds corresponding to the general formulas (VIII) to (XI) of Examples 17 to 20 are further added, the storage characteristics or low-temperature discharge characteristics of the battery can be further improved as compared with the case where each of them is used alone. it can.
Although the detailed reason why the effect is exhibited is unclear, by adding at least one of a cyclic sulfate ester compound and an unsaturated sultone compound and at least one of a phosphazene compound and a halogenated phosphate ester compound, each of them can be used alone. It seems that the ionic conductivity of the film on the negative electrode and the positive electrode is improved and the film is stabilized, compared with the case of using in the above.

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Positive electrode can 4 Sealing plate 5 Separator 6 Gasket 7, 8 Spacer plate

Claims (10)

  A nonaqueous electrolytic solution containing at least one of a cyclic sulfate compound and an unsaturated sultone compound, and at least one of a phosphazene compound and a halogenated phosphate compound. The nonaqueous electrolytic solution according to claim 1, wherein the cyclic sulfate compound is a cyclic sulfate compound represented by the following general formula (I).

[In general formula (I), R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a group represented by general formula (II), or a general formula (III). Or a group that together forms a benzene ring or a cyclohexyl ring together with the carbon atom to which R ¹ is bonded and the carbon atom to which R ² is bonded. In general formula (II), R ³ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or general formula (IV). Represents the group represented. The wavy line in general formula (II), general formula (III), and general formula (IV) represents a bonding position. ] The non-aqueous electrolyte according to claim 1, wherein the unsaturated sultone compound is an unsaturated sultone compound represented by the following general formula (V).

In [Formula ^(V), R 4 ~R ⁷ are each independently a hydrogen atom, an alkyl group having a halogen atom, or a carbon number 1 to 6, n is an integer of 0 to 3. ] The non-aqueous electrolyte according to any one of claims 1 to 3, wherein the phosphazene compound is a phosphazene compound represented by the following general formula (VI).

[In General Formula (VI), R ^{8 to} R ¹³ each independently represents at least one selected from a halogen atom, an alkyl group, an aryl group, an alkoxy group, and an aryloxy group. ] The nonaqueous electrolytic solution according to any one of claims 1 to 4, wherein the halogenated phosphate compound is a halogenated phosphate compound represented by the following general formula (VII).


[In General Formula (VII), each of R ^{14 to} R ¹⁶ independently represents at least one selected from an alkyl group which may be substituted with a halogen atom and an aryl group which may be substituted with a halogen atom. Represent. ] At least one of a compound represented by the following general formula (VIII), a compound represented by the general formula (IX), a compound represented by the general formula (X), and a compound represented by the general formula (XI): The non-aqueous electrolyte of any one of Claims 1-5 containing.

[In General Formula (VIII), M represents an alkali metal, Y represents a transition element or a group 13, 14 or 15 element of the periodic table, b represents an integer of 1 to 3, and m represents 1 An integer of ˜4, n is an integer of 0 to 8, and q is 0 or 1. R ¹⁷ is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a hetero atom, and when q is 1 and m is 2 to 4, m R ^{17 s} may be bonded to each other. ¹⁸ is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (these groups are In the structure, a substituent or a hetero atom may be contained, and when n is 2 to 8, n R ^{18 s} may be bonded to each other to form a ring), or It represents a -Q ³ R ^19. Q ¹ , Q ² and Q ³ each independently represent O, S or NR ²⁰ , and R ¹⁹ and R ²⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or 1 to 1 carbon atoms. A halogenated alkyl group having 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups may contain a substituent or a hetero atom in the structure; ^{And a} plurality of ¹⁹ or R ²⁰ may be bonded to each other to form a ring). ]

[In general formula (IX), X represents an alkali metal or a C1-C12 hydrocarbon group. ]

[In General Formula (X), R ²¹ and R ²² each independently represent a hydrogen atom, a methyl group, an ethyl group, or a propyl group. ]

[In General Formula (XI), R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are each independently a hydrocarbon group having 1 to 6 carbon atoms or an alkyl having 1 to 3 carbon atoms which may be substituted with a fluorine atom. Group, a C6-C12 aryl group, a hydrogen atom, a fluorine atom, or a chlorine atom. However, R ^{23 to} R ²⁶ are not simultaneously hydrogen atoms. ]   The total content of the cyclic sulfate ester compound and the unsaturated sultone compound is 0.01% by mass to 10% by mass with respect to the total amount of the nonaqueous electrolytic solution. Water electrolyte.   The total content of the phosphazene compound and the halogenated phosphate ester compound is 0.01% by mass to 30% by mass with respect to the total amount of the non-aqueous electrolyte solution. Water electrolyte.   The total content of the compound represented by the general formula (VIII), the compound represented by the general formula (IX), the compound represented by the general formula (X), and the compound represented by the general formula (XI) is The nonaqueous electrolytic solution according to claim 6, which is 0.01 mass% to 10 mass% of the total amount of the nonaqueous electrolytic solution.   A positive electrode and metallic lithium, a lithium-containing alloy, a metal or alloy that can be alloyed with lithium, an oxide that can be doped / undoped with lithium ions, a transition metal nitride that can be doped / undoped with lithium ions, And a negative electrode containing, as a negative electrode active material, at least one selected from a carbon material capable of doping and dedoping lithium ions, and the nonaqueous electrolytic solution according to any one of claims 1 to 9 , Including lithium secondary battery.