JP2014063668A - Electrolyte for nonaqueous secondary battery and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery excellent in high-temperature cycle characteristics and high-rate discharge characteristics, and an electrolyte for a nonaqueous secondary battery, used for the secondary battery.SOLUTION: An electrolyte for a nonaqueous secondary battery contains a specific compound and an electrolyte in an organic solvent, the specific compound having a part, where an active species is produced by electrolytic oxidation or electrolytic reduction, and a polymerizable part in the molecule.

Description

  The present invention relates to an electrolyte for a non-aqueous secondary battery containing an organic solvent and a secondary battery using the same.

  Portable electronic devices are indispensable as tools for modern social life and business. With the further development and diversification, the performance of the battery that is the power source is increasingly attracting attention. In order to meet these needs, it is essential to reduce the size, weight, and capacity of power supplies. In addition, battery stability, reliability, and safety are also required.

  On the other hand, the lithium ion secondary battery realizes a high operating voltage of 3 to 4 V, while the conventional aqueous battery is about 1.2 V. Moreover, it is excellent also in lightness. Furthermore, there is no memory effect which is a problem with nickel / cadmium storage batteries or nickel / hydrogen storage batteries, and stable energy supply is possible. Against this background, mobile phones and notebook PCs are used mainly as substitutes for other secondary batteries, and their share is growing rapidly. Recently, the range of use has expanded to electric assist bicycles, electric tools, hybrid vehicles, electric vehicles, robots, spacecrafts, aircraft, etc., and further development is expected in the future.

  In response to the situation as described above, efforts to improve the performance are being promoted in various directions. Specifically, an attempt is made to search for materials and structures that constitute a positive electrode active material, a negative electrode active material, a separator, an electrolytic solution, etc., and improve discharge characteristics and battery stability. An example in which a polymerizable compound is added is disclosed as an improvement technique related to an electrolytic solution (see Patent Documents 1 to 6).

JP 2006-216276 A JP 2003-151621 A JP 2003-031259 A JP 2004-103372 A Japanese Patent No. 3,163,078 Japanese Patent No. 4,050,251

  The demand for improvement of secondary batteries, including expansion to automotive applications, is increasingly toward higher performance and multi-functionality. In particular, secondary batteries tend to be charged / discharged / stored in various temperature / capacity ranges, and it is desired to realize high performance even in such an environment. Therefore, the present inventor has focused on improving battery capacity maintenance and high rate discharge characteristics when storing at high temperature in a fully charged state. In general, there are not enough efforts to improve these problems.

  This invention is made | formed in view of this point, The objective is to provide the secondary battery which is excellent in a high temperature cycling characteristic and a high-rate discharge characteristic, and the electrolyte solution for non-aqueous secondary batteries used for this.

（式中Ｒ^１は、アルキル基またはアリール基を示す。Ｒ^２およびＲ^３は、それぞれ、フッ素原子または有機基を示す。Ｒ^７はアルキル基、カルボニル基含有基、アリール基、ヘテロアリール基を示す。Ｒ^８〜Ｒ^１１はそれぞれ水素原子、アルキル基、アリール基を示す。Ｒ^１とベンゼン環Ａ^１、Ｒ^７とベンゼン環Ａ^２、Ｒ^８とＲ^９は連結基を介して互いに結合していてもよい。Ｍは、重合性部位を有する置換基を示す。ｎ１は０〜５の整数を表す。ｎ２は０〜４の整数を表す。）
〔３〕重合性部位がビニル基、スチレン構造基、アクリロイル基、またはメタクリロイル基を有する置換基である〔１〕または〔２〕に記載の非水二次電池用電解液。
〔４〕特定化合物が、下記式（１−１）〜（１−３）、（２−１）、（２−２）、および（３−１）のいずれかで表される化合物である〔１〕〜〔３〕のいずれかに記載の非水二次電池用電解液。

（式中、Ｒ^２、Ｒ^３、ｎ１、ｎ２、及びＭは式（１）及び（２）と同義である。ベンゼン環Ａ^３とベンゼン環Ａ^４とは連結基を介して互いに結合していてもよい。連結基としては、単結合、アルキレン基、アリーレン基、エーテル基、チオエーテル基、カルボニル基、アミノ連結基を示す。Ｒ^２１およびＲ^２２は、それぞれ、水素原子、アルキル基、アリール基を示す。Ｘは、アルキレン基、アリーレン基、エーテル基、チオエーテル基、カルボニル基、アミノ連結基を示す。）

（式中、Ｒ^２、Ｒ^３、ｎ１、ｎ２、及びＭは式（１）及び（２）と同義である。ベンゼン環Ａ^５とＡ^６とは連結基を介して互いに結合していてもよい。連結基としては、単結合、アルキレン基、アリーレン基、エーテル基、チオエーテル基、カルボニル基、アミノ基（−ＮＲ−：Ｒは水素原子もしくは置換基）を示す。Ｒ^４、Ｒ^５は、それぞれ、水素原子またはアルキル基を示す。Ｙはアルコキシ基もしくはアミノ基を示す。）

（式中、Ｒ^３１〜Ｒ^３４は、それぞれ独立に水素原子又はアルキル基を示す。Ｇは、それぞれ独立に、水素原子、アルキル基、アルコキシ基、又はアミノ基を示す。Ｅは連結基を示し、アルキレン基、エーテル基、アミノ基（−ＮＲ−：Ｒは水素原子もしくは置換基）、又はこれらを組み合わせた基を示す。）
〔５〕重合性部位が下記式（Ｍ−１）〜（Ｍ−３）のいずれかで表される構造部である〔１〕〜〔４〕のいずれかに記載の非水二次電池用電解液。

（式中、Ｌは、単結合、アルキレン基、エステル基、エーテル基、チオエーテル基、またはそれらの組合せを示す。＊は活性種生成部位と結合する部位を示す。Ｒ^ａは水素原子又は置換基を示す。Ｒ^ｂは水素原子または置換基を示す。ｎ４は０〜４の整数を表す。）
〔６〕特定化合物を０．０００１〜０．０５ｍｏｌ／Ｌ含有する〔１〕〜〔５〕のいずれかに記載の非水二次電池用電解液。
〔７〕正極と負極とセパレータと〔１〕〜〔６〕のいずれかに記載の電解液とを具備する二次電池。
〔８〕正極の活物質がニッケルとマンガンとコバルトとを有する物質で構成された〔７〕に記載の二次電池。
〔９〕負極の活物質がチタン酸リチウムで構成された〔７〕または〔８〕に記載の二次電池。
〔１０〕電解質を含有する第１剤と、分子内に電解酸化もしくは電解還元により活性種を生成する部位と重合性部位とを持つ特定化合物を含有する第２剤とを組み合わせた非水二次電池電解液用キット。
〔１１〕特定化合物が下記式（１）〜（３）のいずれかで表される化合物である〔１０〕に記載の非水二次電池電解液用キット。

（式中Ｒ^１は、アルキル基またはアリール基を示す。Ｒ^２およびＲ^３は、それぞれ、フッ素原子または有機基を示す。Ｒ^７はアルキル基、カルボニル基含有基、アリール基、ヘテロアリール基を示す。Ｒ^８〜Ｒ^１１はそれぞれ水素原子、アルキル基、アリール基を示す。Ｒ^１とベンゼン環Ａ^１、Ｒ^７とベンゼン環Ａ^２、Ｒ^８とＲ^９は連結基を介して互いに結合していてもよい。Ｍは、重合性部位を有する置換基を示す。ｎ１は０〜５の整数を表す。ｎ２は０〜４の整数を表す。） That is, the above problem has been solved by the following means.
[1] An electrolyte solution for a non-aqueous secondary battery containing, in an organic solvent, a specific compound having a site that generates active species by electrolytic oxidation or electrolytic reduction in the molecule and a polymerizable site, and an electrolyte.
[2] The electrolyte solution for a non-aqueous secondary battery according to [1], wherein the specific compound is a compound represented by any of the following formulas (1) to (3).

(In the formula, R ¹ represents an alkyl group or an aryl group. R ² and R ³ each represents a fluorine atom or an organic group. R ⁷ represents an alkyl group, a carbonyl group-containing group, an aryl group, or a heteroaryl group. R ^{8 to} R ¹¹ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and benzene ring A ¹ , R ⁷ and benzene ring A ² , and R ⁸ and R ⁹ are bonded to each other via a linking group. M represents a substituent having a polymerizable moiety, n1 represents an integer of 0 to 5, and n2 represents an integer of 0 to 4.)
[3] The electrolyte solution for a nonaqueous secondary battery according to [1] or [2], wherein the polymerizable site is a substituent having a vinyl group, a styrene structure group, an acryloyl group, or a methacryloyl group.
[4] The specific compound is a compound represented by any of the following formulas (1-1) to (1-3), (2-1), (2-2), and (3-1) [ 1]-[3] The electrolyte solution for non-aqueous secondary batteries.

(Wherein R ² , R ³ , n1, n2, and M have the same meanings as in formulas (1) and (2). The benzene ring A ³ and the benzene ring A ⁴ are bonded to each other via a linking group. Examples of the linking group include a single bond, an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, and an amino linking group, wherein R ²¹ and R ²² are a hydrogen atom, an alkyl group, and an aryl group, respectively. X represents an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, or an amino linking group.)

(Wherein R ² , R ³ , n1, n2, and M have the same meanings as in formulas (1) and (2). The benzene rings A ⁵ and A ⁶ may be bonded to each other via a linking group. Examples of the linking group include a single bond, an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, and an amino group (—NR—: R is a hydrogen atom or a substituent), and R ⁴ and R ⁵ are Each represents a hydrogen atom or an alkyl group, and Y represents an alkoxy group or an amino group.)

(In the formula, R ^{31 to} R ³⁴ each independently represent a hydrogen atom or an alkyl group. G independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an amino group. E represents a linking group. , An alkylene group, an ether group, an amino group (-NR-: R represents a hydrogen atom or a substituent), or a group obtained by combining these.)
[5] The non-aqueous secondary battery according to any one of [1] to [4], wherein the polymerizable site is a structural part represented by any of the following formulas (M-1) to (M-3) Electrolytic solution.

(In the formula, L represents a single bond, an alkylene group, an ester group, an ether group, a thioether group, or a combination thereof. * Represents ^a site bonded to the active species generating site. ^Ra represents ^a hydrogen atom or a substituent. R ^b represents a hydrogen atom or a substituent, and n4 represents an integer of 0 to 4.)
[6] The electrolyte solution for a nonaqueous secondary battery according to any one of [1] to [5], containing a specific compound in an amount of 0.0001 to 0.05 mol / L.
[7] A secondary battery comprising a positive electrode, a negative electrode, a separator, and the electrolyte solution according to any one of [1] to [6].
[8] The secondary battery according to [7], wherein the positive electrode active material is composed of a material having nickel, manganese, and cobalt.
[9] The secondary battery according to [7] or [8], wherein the negative electrode active material is composed of lithium titanate.
[10] A non-aqueous secondary in which a first agent containing an electrolyte and a second agent containing a specific compound having a site that generates an active species by electrolytic oxidation or electrolytic reduction in the molecule and a polymerizable site Battery electrolyte kit.
[11] The nonaqueous secondary battery electrolyte solution kit according to [10], wherein the specific compound is a compound represented by any of the following formulas (1) to (3).

(In the formula, R ¹ represents an alkyl group or an aryl group. R ² and R ³ each represents a fluorine atom or an organic group. R ⁷ represents an alkyl group, a carbonyl group-containing group, an aryl group, or a heteroaryl group. R ^{8 to} R ¹¹ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and benzene ring A ¹ , R ⁷ and benzene ring A ² , and R ⁸ and R ⁹ are bonded to each other via a linking group. M represents a substituent having a polymerizable moiety, n1 represents an integer of 0 to 5, and n2 represents an integer of 0 to 4.)

  In this specification, when there are a plurality of substituents or linking groups indicated by a specific symbol, or when a plurality of substituents are specified simultaneously or alternatively, each of the substituents may be the same or different from each other. It may be. The same applies to the definition of the number of substituents and the like. Further, even if not specifically stated, when a plurality of substituents and the like are close to each other, they may be connected to each other or condensed to form a ring.

  The non-aqueous electrolyte and non-aqueous secondary battery of the present invention are excellent in high temperature cycle characteristics and high rate discharge characteristics.

It is sectional drawing which shows typically the mechanism of the lithium secondary battery which concerns on preferable embodiment of this invention. It is sectional drawing which shows the specific structure of the lithium secondary battery which concerns on preferable embodiment of this invention.

  The electrolyte solution for a non-aqueous secondary battery of the present invention is a compound having both a site that generates active species in the molecule by electrolytic oxidation or electrolytic reduction and a polymerizable site (hereinafter referred to as “active species-containing polymerizable compound”). In some cases). Thereby, the improvement in specific battery performance was expressed. The reason for this is not clear, but is estimated as follows. In an electrolytic solution to which a conventionally proposed polymerizable compound is added, SEI (Solid Electrolyte Interface) is formed on the electrode surface by the polymer, and performance improvement can be expected. On the other hand, in the present invention, it is considered that the active species-containing polymerizable compound releases active species during battery operation, and this promotes the reaction of the polymerizable site of the compound more effectively. Further, it is considered that the terminal formed by dissociation of the active species or the dissociating terminal on the polymerizable site side forms a specific active site, which may further contribute to the formation of a polymer. As a result, it was inferred that SEI was produced in a form that could not be achieved with the conventional polymerizable compound, and contributed to the improvement of battery performance. Hereinafter, preferred embodiments of the present invention will be described in detail.

[Electrolyte for non-aqueous secondary battery]
(Active species-containing polymerizable compound)
The active species-containing polymerizable compound is preferably a compound having a structure selected from the following formulas (1) to (3).

・ R ¹
In the formula, R ¹ represents an alkyl group or an aryl group. The alkyl group may be linear or branched, and may be linear or cyclic. 1-12 are preferable and, as for carbon number of an alkyl group, 1-6 are more preferable. Among these, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a benzyl group, and a phenylethyl group are preferable as the alkyl group. 6-24 are preferable and, as for carbon number of the said aryl group, 6-12 are more preferable.

R ¹ and the benzene ring A ¹ may be bonded to each other via a linking group La. As the linking group La, a single bond, an alkylene group (preferably having a carbon number of 1 to 6), an arylene group (preferably having a carbon number of 6 to 36), an amino group (—NR—: R is a hydrogen atom or a substituent), Examples include an oxygen atom (ether group), a sulfur atom (thioether group), a carbonyl group, or a linking group obtained by combining these. Of these, a carbonyl group, a sulfur atom, and an oxygen atom are preferable. In the present invention, the linking group means a single bond. In addition, when R of the amino group (—NR—) is a substituent, an alkyl group is preferable. The amino group preferably has 0 to 6 carbon atoms. Hereinafter, the amino group (—NR—) is synonymous with this unless otherwise specified. In the present specification, the linking group means a single bond unless otherwise specified as in the example of the linking group La.

・ R ² , R ³
R ² and R ³ represent a fluorine atom or an organic group. As the organic group, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 24 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, An amino group having 0 to 6 carbon atoms is exemplified. Especially, R < ² >, R < ³ > has a hydrogen atom, a fluorine atom, and a C1-C6 alkyl group, and a hydrogen atom is more preferable. The organic group may further have a substituent T described later.

・ N1, n2
n1 represents the integer of 0-5. n2 represents an integer of 0 to 4. When n1 and n2 are 2 or more, the plurality of structural sites defined thereby may be different from each other.

・ R ⁷
R ⁷ represents a substituent. Among them, R ⁷ is preferably an alkyl group, a carbonyl group-containing group, an aryl group, or a heteroaryl group, an aryl group that may have a substituent, or an alkyl that may have a substituent (preferably an amino group). An arylcarbonyl group which may have a group or a substituent is more preferable.
The aryl group which may have a substituent is preferably 6 to 24 carbon atoms including the substituent. Examples of the aryl group which may have a substituent include a 9-fluorenone structural group which may have a substituent and a benzophenone structural group which may have a substituent. Examples of the substituent include the substituent T described later.
The alkyl group that may have a substituent (preferably an amino group) preferably has 1 to 24 carbon atoms, more preferably 3 to 12 carbon atoms, including the substituent. The amino group that may be substituted with an alkyl group is preferably a cyclic amino group, more preferably a 5- to 7-membered cyclic amino group, and specific examples include a piperidino group, a piperazino group, and a morpholino group.
R ⁷ and the benzene ring A ² may be linked via the linking group La.

· ^R 8 ~R ¹¹
R < ⁸ > -R < ¹¹ > shows a hydrogen atom, an alkyl group (preferably C1-C12), and an aryl group (preferably C6-C24), respectively. R ⁸ and R ⁹ may be bonded to each other through the linking group La.

・ M
M represents a substituent having a polymerizable site. The polymerizable site is preferably a substituent having a vinyl group, a styrene structure group, an acryloyl group, or a methacryloyl group. In the formula (1), the polymerizable site is preferably a group containing a vinyl group, an acryloyl group (more preferably an acryloyloxy group), or a methacryloyl group (more preferably a methacryloyloxy group). In the formulas (2) and (3), a group containing a vinyl group, an acryloyl group (more preferably an acryloyloxy group), a methacryloyl group (more preferably a methacryloyloxy group) or a styrene structure group is preferable. The styrene structural group means a group in which styrene is substituted with its benzene ring, and may be referred to as a vinylphenyl group which may have a substituent.

The substituent M having a polymerizable group is preferably a group represented by any of the following formulas (M-1) to (M-3).

  L represents a linking group and is preferably a single bond, an alkylene group, an ester group, an ether group or a thioether group. Ra represents a hydrogen atom or a substituent, and examples of the substituent T are described later. Especially, it is preferable that the substituent selected as Ra is an alkyl group, and it is preferable that it is a C1-C6 alkyl group. Rb represents a hydrogen atom or a substituent, and the substituent is preferably an alkyl group (preferably having 1 to 6 carbon atoms). n4 represents an integer of 0 to 4. When n4 is 2 or more, the plurality of structural sites defined thereby may be different from each other.

The active species-containing polymerizable compound is preferably a compound represented by any of the following formulas (1-1) to (1-3).

・ R ² , R ³ , n1, n2, M
In the formula, R ² , R ³ , n1, n2, and M are as defined in the above formulas (1) and (2).

· ^{R 21, R 22}
R <^21> , R <^22> shows a hydrogen atom, an alkyl group (preferably C1-C5), and an aryl group (preferably C6-C10).
・ A ³ , A ⁴
The benzene rings A ³ and A ⁴ may be linked to form a ring. Examples of the linking group include La.

・ X
X represents a linking group, an alkylene group (preferably having 1 to 2 carbon atoms), an arylene group (preferably having 6 to 10 carbon atoms), an ether group, a thioether group, a carbonyl group, an amino group (—NR—) (preferably Carbon number 1-5) is shown.

・ R ² , R ³ , n1, n2, M
R ² , R ³ , n1, n2, and M are as defined in formulas (1) and (2). When n1 and n2 are 2 or more, the plurality of structural sites defined thereby may be different from each other.

· ^A 5, ^{A 6}
The benzene rings A ⁵ and A ⁶ may be linked to each other via a linking group. The linking group represents the linking group La.

・ R ⁴ , R ⁵
R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group (preferably having 1 to 4 carbon atoms).

・ Y
Y represents an alkoxy group (preferably having 1 to 6 carbon atoms) or an amino group (preferably having 2 to 6 carbon atoms). The amino group is preferably the amino group described for R ⁷ above.

・ R ^{31 to} R ³⁴
In the formula, R ^{31 to} R ³⁴ each independently represent a hydrogen atom or an alkyl group (preferably having 1 to 3 carbon atoms).

・ G
G represents a hydrogen atom, an alkyl group (preferably having 1 to 3 carbon atoms), an alkoxy group (preferably having 1 to 3 carbon atoms), or an amino group (preferably having 2 to 7 carbon atoms).

・ E
E represents a linking group, an alkylene group (preferably having 2 to 5 carbon atoms), an ether group (preferably having 1 to 5 carbon atoms), an amino group (—NR—) (preferably having 2 to 10 carbon atoms), or these The group which combined is shown.

・ M
M is synonymous with the formulas (1) and (2).

Synthetic examples are shown below as representative examples of the exemplified compounds.
(Synthesis Example 1: Synthesis of (M-1))
A solution of 4.88 g of acridone, 3.82 g of 4- (chloromethyl) styrene, 1 g of sodium hydroxide and 50 ml of DMF was reacted at 50 ° C. for 3 hours. After completion of the reaction, the reaction solution was poured into 300 ml of distilled water, filtered under reduced pressure, washed with distilled water and dried to obtain 2.58 g of compound (M-1).

(Synthesis Example 2: Synthesis of (M-4))
In the same manner as in Synthesis Example 1, 1.1 g of compound (M-4) was obtained using diphenylamine as a raw material.

(Synthesis Example 3: Synthesis of (M-10))
Using 2-phenyl-1H-benzimidazole as a raw material, 2.14 g of Compound (M-10) was obtained in the same manner as in Synthesis Example 1.

  The addition amount of the active species-containing polymerizable compound (A) is preferably 0.0001 mol / L% or more, more preferably 0.0003 mol / L% or more, and further 0.0005 mol / L% or more with respect to the total electrolyte solution. preferable. As an upper limit, 0.1 mol / L% or less is preferable, 0.05 mol / L% or less is more preferable, 0.01 mol / L% or less is especially preferable. By making this addition amount into the above range, it is preferable that good discharge performance can be maintained and desired high-temperature capacity maintenance and high rate characteristics can be achieved at a high level.

  In addition, in the present specification, a substituent that does not specify substitution / non-substitution (the same applies to a linking group) means that the group may have an arbitrary substituent. This is also synonymous for compounds that do not specify substitution / non-substitution. Preferred substituents include the following substituent T.

Examples of the substituent T include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl, etc.), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, Phenyl, 1-naphthyl, 4-methoxyphenyl, -Chlorophenyl, 3-methylphenyl, etc.), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, preferably a 5- or 6-membered heterocycle having at least one oxygen atom, sulfur atom, nitrogen atom) A cyclic group is preferable, for example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc., an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, Methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), An alkoxycarbonyl group (preferably an alkoxycarbonyl having 2 to 20 carbon atoms) Nyl groups such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc., amino groups (preferably including amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, such as amino, N, N-dimethyl Amino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfonamido groups having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl) Etc.), an acyl group (preferably an acyl group having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, benzoyl, etc.), an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, Benzoyloxy, etc.), carbamoyl groups (preferably C 1-20 carbon atoms) Rubamoyl groups such as N, N-dimethylcarbamoyl and N-phenylcarbamoyl), acylamino groups (preferably having 1 to 20 carbon atoms, such as acetylamino and benzoylamino), sulfonamido groups (preferably Is a sulfamoyl group having 0 to 20 carbon atoms, such as methanesulfonamide, benzenesulfonamide, N-methylmethanesulfonamide, N-ethylbenzenesulfonamide, etc., an alkylthio group (preferably an alkylthio having 1 to 20 carbon atoms). Groups such as methylthio, ethylthio, isopropylthio, benzylthio, etc., arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio ), An alkyl or arylsulfonyl group (preferably an alkyl or arylsulfonyl group having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, benzenesulfonyl, etc.), a hydroxyl group, a cyano group, a halogen atom (for example, a fluorine atom, chlorine) Atoms, bromine atoms, iodine atoms, etc.), more preferably alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, amino groups, acylamino groups, hydroxyl groups or halogen atoms. And particularly preferably an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a hydroxyl group.
In addition, each of the groups listed as the substituent T may be further substituted with the substituent T described above.

  When the compound or substituent / linking group contains an alkyl group / alkylene group, alkenyl group / alkenylene group, etc., these may be cyclic or chain-like, and may be linear or branched, and substituted as described above. It may be substituted or unsubstituted. Moreover, when an aryl group, a heterocyclic group, etc. are included, they may be monocyclic or condensed and may be similarly substituted or unsubstituted.

(Organic solvent)
Examples of the organic solvent used in the present invention include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methylpropyl carbonate, γ-butyrolactone, cyclic esters such as γ-valerolactone, chain ethers such as 1,2-dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, Chain ethers such as 1,3-dioxane, 1,4-dioxane and other cyclic ethers, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate and ethyl trimethylacetate Nitrile compounds such as steal, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N′-dimethylimidazolidinone Nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide or dimethyl sulfoxide phosphoric acid. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of cyclic carbonates (preferably ethylene carbonate, propylene carbonate), chain carbonates (preferably dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate), cyclic esters (preferably γ-butyrolactone). It is preferable to contain a seed, more preferably a solvent containing a cyclic carbonate and a chain carbonate, or a solvent containing a cyclic carbonate and a cyclic ester, particularly preferably a high solvent such as ethylene carbonate or propylene carbonate. A combination of a viscosity (high dielectric constant) solvent (for example, dielectric constant ε ≧ 30) and a low viscosity solvent (for example, viscosity ≦ 1 mPa · s) such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, or γ-butyrolactone. . This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

(Electrolytes)
Examples of the electrolyte that can be used in the electrolytic solution of the present invention include metal ions or salts thereof, and metal ions or salts thereof belonging to Group 1 or Group 2 of the periodic table are preferred. It is appropriately selected depending on the purpose of use of the electrolytic solution, for example, lithium salt, potassium salt, sodium salt, calcium salt, magnesium salt and the like. When used in a secondary battery, the lithium salt is used from the viewpoint of output. Is preferred. When the electrolytic solution of the present invention is used as an electrolyte of a non-aqueous electrolytic solution for a lithium secondary battery, a lithium salt may be selected as a metal ion salt. The lithium salt is not particularly limited as long as it is a lithium salt usually used for an electrolyte of a non-aqueous electrolyte solution for a lithium secondary battery. For example, those described below are preferable.

(L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(L-2) Fluorine-containing organic lithium salt: Perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF _{3 )], Li [PF 4 (} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(L-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.
Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) ₂ is preferred, such as LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) ₂ The lithium imide salt is more preferable. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.
In addition, the lithium salt used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.
The content of the metal ions belonging to Group 1 or Group 2 of the periodic table or the metal salt thereof in the electrolytic solution is added in an amount so as to obtain a preferable salt concentration described below in the method for preparing the electrolytic solution. The salt concentration is appropriately selected depending on the purpose of use of the electrolytic solution, but is generally 10% by mass to 50% by mass, more preferably 15% by mass to 30% by mass, based on the total mass of the electrolytic solution. In addition, when evaluating as an ion density | concentration, what is necessary is just to calculate by salt conversion with the metal applied suitably.
(Other ingredients)
In order to improve the performance, safety and durability of the battery, various additives can be used in the electrolytic solution according to the present invention as long as the effects of the present invention are not impaired. As such an additive, such a functional additive such as an overcharge inhibitor, a negative electrode film forming agent, a positive electrode protective agent, a flame retardant, and the like may be used.
Specifically, carbonate compounds such as vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, sulfur-containing compounds such as ethylene sulfite, propane sultone, sulfonic acid ester, biphenyl, cyclohexylbenzene, t-amyl Aromatic compounds such as benzene and phosphorus compounds such as phosphate esters can be mentioned. The content ratio of these other additives in the non-aqueous electrolyte solution is not particularly limited, but is preferably 0.01% by mass or more, particularly preferably 0.1% by mass with respect to the total organic components of the non-aqueous electrolyte solution. % Or more, more preferably 0.2% by mass or more, and the upper limit is preferably 5% by mass or less, particularly preferably 3% by mass or less, and further preferably 2% by mass or less. By adding these compounds, it is possible to suppress rupture / ignition of the battery at the time of abnormality due to overcharge, and to improve the capacity maintenance characteristic and cycle characteristic after high-temperature storage.

[Method for preparing electrolytic solution]
The electrolyte solution for a non-aqueous secondary battery of the present invention can be prepared by a conventional method by dissolving the above components in the non-aqueous electrolyte solvent, including an example using a lithium salt as a metal ion salt. .

  In the present invention, “non-water” means that water is not substantially contained, and a trace amount of water may be contained as long as the effects of the invention are not hindered. In view of obtaining good characteristics, the water content is preferably 200 ppm or less, and more preferably 100 ppm or less. Although there is no particular lower limit, it is practical that it is 10 ppm or more considering inevitable mixing. The viscosity of the electrolytic solution of the present invention is not particularly limited, but is preferably 10 to 0.1 mPa · s, more preferably 5 to 0.5 mPa · s at 25 ° C.

[Secondary battery]
As a preferred embodiment of the present invention, a lithium ion secondary battery will be described with reference to FIG. The lithium ion secondary battery 10 of this embodiment includes the electrolyte solution 5 for a non-aqueous secondary battery of the present invention and a positive electrode C capable of inserting and releasing lithium ions (a positive electrode current collector 1 and a positive electrode active material layer 2). And a negative electrode A (negative electrode current collector 3, negative electrode active material layer 4) capable of inserting and releasing lithium ions or dissolving and depositing lithium ions. In addition to these essential members, considering the purpose of use of the battery, the shape of the potential, etc., a separator 9 disposed between the positive electrode and the negative electrode, a current collecting terminal (not shown), an outer case, etc. (Not shown). If necessary, a protective element may be attached to at least one of the inside of the battery and the outside of the battery. By adopting such a structure, lithium ion transfer a and b occurs in the electrolytic solution 5, charging α and discharging β can be performed, and operation or power storage is performed via the operation mechanism 6 via the circuit wiring 7. It can be performed. Hereinafter, the configuration of the lithium secondary battery which is a preferred embodiment of the present invention will be described in more detail.

(Battery shape)
The battery shape to which the lithium secondary battery of the present embodiment is applied is not particularly limited, and examples thereof include a bottomed cylindrical shape, a bottomed square shape, a thin shape, a sheet shape, and a paper shape. Any of these may be used. Further, it may be of a different shape such as a horseshoe shape or a comb shape considering the shape of the system or device to be incorporated. Among them, from the viewpoint of efficiently releasing the heat inside the battery to the outside, a square shape such as a bottomed square shape or a thin shape having at least one surface that is relatively flat and has a large area is preferable.

  In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 is an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18.

In the bottomed square shape, the ratio of the area S of the largest surface (the product of the width and height of the outer dimensions excluding the terminal portion, unit cm ² ) to the thickness T (unit cm) of the battery outer shape The 2S / T value is preferably 100 or more, and more preferably 200 or more. By increasing the maximum surface, it is possible to improve characteristics such as cycle performance and high-temperature storage even for high-power and large-capacity batteries, and increase the heat dissipation efficiency during abnormal heat generation. It is possible to suppress a dangerous state of “rupture”.

(Members constituting the battery)
The lithium secondary battery according to the present embodiment is configured to include the electrolytic solution 5, the positive electrode and negative electrode electrode mixtures C and A, and the separator basic member 9, based on FIG. 1. Hereinafter, each of these members will be described.
(Electrode mixture)
The electrode mixture is obtained by applying a dispersion of an active material and a conductive agent, a binder, a filler, etc. on a current collector (electrode substrate). In a lithium battery, the active material is a positive electrode active material. It is preferable to use a negative electrode mixture in which the positive electrode mixture and the active material are a negative electrode active material. Next, each component in the dispersion (electrode composition) constituting the electrode mixture will be described.

-Positive electrode active material You may use a particulate positive electrode active material for a positive electrode active material. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but a lithium-containing transition metal oxide is preferably used. Preferred examples of the lithium-containing transition metal oxide preferably used as the positive electrode active material include oxides containing lithium-containing Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, and W. Alkali metals other than lithium (elements of Group 1 (Ia) and Group 2 (IIa) of the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P , B, etc. may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

  Among the lithium-containing transition metal oxides preferably used as the positive electrode active material, a lithium compound / transition metal compound (wherein the transition metal is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is more preferable that the mixture is synthesized so that the total molar ratio of the compound is 0.3 to 2.2.

Further, among the lithium compounds / transition metal compounds, Li _g M3O ₂ (M3 represents one or more elements selected from Co, Ni, Fe, and Mn. G represents 0 to 1.2. ) Or a material having a spinel structure represented by Li _h M4 ₂ O (M4 represents Mn. H represents 0 to 2). As M3 and M4, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be mixed in addition to the transition metal. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

The _Li g M3O material containing _2, among the materials having the spinel structure represented by _{Li h M4 2 O, Li g} CoO 2, Li g NiO 2, Li g MnO 2, Li g Co j Ni 1-j O _{2, Li h Mn 2 O 4} , LiNi j Mn 1-j O 2, LiCo j Ni h Al 1-j-h O 2, LiCo j Ni h Mn 1-j-h O 2, LiMn h Al 2-h O ₄ , LiMn _h Ni _{2 -h} O ₄ (where g represents 0.02 to 1.2, j represents 0.1 to 0.9, and h represents 0 to 2) is particularly preferable. , most preferably _{Li g CoO 2, LiMn 2 O} 4, LiNi 0.85 Co 0.01 Al 0.05 O 2, and is _{LiNi 0.33 Co 0.33 Mn 0.33 O 2} . Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output. Here, the g value and the h value are values before the start of charge / discharge, and are values that increase / decrease due to charge / discharge. In particular,
LiCoO ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.01 Al _0.05 O ₂ ,
LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn _1.8 Al _0.2 O ₄ ,
LiMn _1.5 Ni _0.5 O ₄ and the like.

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

In the nonaqueous secondary battery of the present invention, the average particle size of the positive electrode active material used is not particularly limited, but is preferably 0.1 μm to 50 μm. No particular limitation is imposed on the specific surface area, preferably from 0.01m ² / g~50m ² / g by the BET method. Further, the pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

  In order to make the positive electrode active substance have a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

In the present invention, it is preferable to use a material having a charge region of 4.25 V or more for the positive electrode active material.
The following are mentioned as a positive electrode active material which has the said specific charge area | region.
(I) LiNi _x Mn _y Co _z O ₂ (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1),
Representative:
LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (also described as LiNi _0.33 Mn _0.33 Co _0.33 O ₂ )
LiNi _1/2 Mn _1/2 O ₂ (also described as LiNi _0.5 Mn _0.5 O ₂ )
(Ii) LiNi _x Co _y Al _z O ₂ (x> 0.7, y> 0.1, 0.1>z> 0.05, x + y + z = 1)
Representative:
LiNi _0.8 Co _0.15 Al _0.05 O ₂
The following can be used as the positive electrode active material having the specific charging region.
(A) LiCoMnO ₄
(B) Li ₂ FeMn ₃ O ₈
(C) Li ₂ CuMn ₃ O ₈
(D) Li ₂ CrMn ₃ O ₈
(E) Li ₂ NiMn ₃ O ₈
Furthermore, a solid solution positive electrode material (for example, Li ₂ MnO ₃ -LiMO ₂ (M: metal such as Ni, Co, Mn)) having a high potential close to 5 V and a very high specific capacity exceeding 250 mAh / g is the next generation lithium. It has attracted much attention as a positive electrode material for ion batteries, and the electrolytic solution of the present invention is preferably combined with these solid solution positive electrode materials.

・ Negative electrode active material The negative electrode active material is not particularly limited as long as it can reversibly insert and release lithium ions. Carbonaceous materials, metal oxides such as tin oxide and silicon oxide, metal composite oxides, Examples thereof include lithium alloys such as lithium alone and lithium aluminum alloys, and metals capable of forming an alloy with lithium such as Sn and Si.
These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of safety.
Further, the metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. .

  The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

  These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the surface spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

  The metal oxide and metal composite oxide, which are negative electrode active materials used in the nonaqueous secondary battery, need only contain at least one of them. As the metal oxide and metal complex oxide, amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used. The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex in the region of 20 ° to 40 ° in terms of 2θ values, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, an amorphous oxide of a metalloid element and a chalcogenide are more preferable, and elements of Groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides and chalcogenides composed of one kind of Al, Ga, Si, Sn, Ge, Pb, Sb, Bi or a combination of two or more kinds thereof. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , such as SnSiS ₃ may preferably be mentioned. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

  In the nonaqueous secondary battery of the present invention, the average particle size of the negative electrode active material used is preferably 0.1 μm to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

  The chemical formula of the compound obtained by the firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a mass difference between powders before and after firing as a simple method.

  In the present invention, as the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, Ge, a carbon material capable of inserting and extracting lithium ions or lithium metal, lithium, Preferred examples include lithium alloys and metals that can be alloyed with lithium.

The electrolyte solution of the present invention is preferably combined with a high potential negative electrode (preferably lithium-titanium oxide, a potential of 1.55 V vs. Li metal) and a low potential negative electrode (preferably a carbon material, potential of about 0.1 V vs. Li). Excellent properties are exhibited in any combination with (metal). Further, metal or metal oxide negative electrodes (preferably Si, Si oxide, Si / Si oxide, Sn, Sn oxide, SnB _x P _y O _z , Cu, which can be alloyed with lithium, which are being developed for higher capacity) / Sn and a plurality of these composites), and a battery using a composite of these metals or metal oxides and a carbon material as a negative electrode.

In the present invention, it is also preferable to use lithium titanate, more specifically, lithium-titanium oxide (Li [Li _1/3 Ti _5/3 ] O ₄ ) as the negative electrode active material. By using this as a negative electrode active material, the effect by the active species-containing polymerizable compound is further enhanced, and more excellent battery performance can be exhibited.

-Conductive material As the conductive material, any electronic conductive material that does not cause a chemical change in the configured secondary battery may be used, and any known conductive material may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63- 10148,554)), metal fibers or polyphenylene derivatives (described in JP-A-59-20971) can be contained as a single type or a mixture thereof. Among these, the combined use of graphite and acetylene black is particularly preferable. As addition amount of the said electrically conductive agent, 1-50 mass% is preferable and 2-30 mass% is more preferable. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.

-Binders Examples of binders include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Among them, for example, starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose. , Sodium alginate, polyacrylic acid, sodium polyacrylate, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, etc. Polymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl Redene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, etc. ) (Meth) acrylic ester copolymer containing acrylic ester, (meth) acrylic ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer , Acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate Polyurethane resins, polyester resins, phenolic resins, emulsion (latex) or a suspension such as an epoxy resin is preferable, a latex of polyacrylate, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride is more preferable.

  A binder can be used individually by 1 type or in mixture of 2 or more types. When the amount of the binder added is small, the holding power and cohesive force of the electrode mixture are weakened. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by mass, and more preferably 2 to 10% by mass.

-Filler The electrode compound material may contain the filler. The material forming the filler is preferably formed of a fibrous material that does not cause a chemical change in the secondary battery. Usually, fibrous fillers made of materials such as olefin polymers such as polypropylene and polyethylene, glass, and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 mass% is preferable in a dispersion.

-Current collector As the positive and negative electrode current collectors, it is preferable to use an electron conductor that does not cause a chemical change in the nonaqueous electrolyte secondary battery. As the current collector of the positive electrode, in addition to aluminum, stainless steel, nickel, titanium, etc., the surface of aluminum or stainless steel is preferably treated with carbon, nickel, titanium, or silver. Among them, aluminum and aluminum alloys are preferable. More preferred.

  As the negative electrode current collector, aluminum, copper, stainless steel, nickel, and titanium are preferable, and aluminum, copper, and a copper alloy are more preferable.

As the shape of the current collector, a film sheet shape is usually used, but a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.
An electrode mixture of the lithium secondary battery is formed by a member appropriately selected from these materials.

(Separator)
The separator used in the non-aqueous secondary battery may be formed of a material that mechanically insulates the positive electrode and the negative electrode, ion permeability, and oxidation / reduction resistant at the contact surface between the positive electrode and the negative electrode. preferable. As such a material, a porous polymer material, an inorganic material, an organic-inorganic hybrid material, glass fiber, or the like is used. These separators preferably have a shutdown function for ensuring safety, that is, a function of closing the gap at 80 ° C. or higher to increase resistance and interrupting current, and the closing temperature is 90 ° C. or higher and 180 ° C. or lower. Preferably there is.

  The shape of the hole of the separator is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

  The polymer material may be a single material such as cellulose nonwoven fabric, polyethylene, or polypropylene, or may be a composite material of two or more types. What laminated | stacked the 2 or more types of microporous film which changed the hole diameter, the porosity, the obstruction | occlusion temperature of a hole, etc. is preferable.

  As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. In the thin film shape, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle diameter of less than 1 μm are formed on both surfaces of the positive electrode as a porous layer using a fluororesin binder.

(Production of non-aqueous secondary battery)
As described above, the shape of the non-aqueous secondary battery can be applied to any shape such as a sheet shape, a square shape, and a cylinder shape. A positive electrode active material or a mixture of negative electrode active materials is mainly used after being applied (coated), dried and compressed on a current collector.

  Hereinafter, with reference to FIG. 2, a configuration and a manufacturing method thereof will be described using the bottomed cylindrical lithium secondary battery 100 as an example. In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 shows an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18. In addition, in the figure, 20 is an insulating plate, 22 is a sealing plate, 24 is a positive current collector, 26 is a gasket, 28 is a pressure-sensitive valve element, and 30 is a current interruption element. In addition, although the illustration in the enlarged circle has changed hatching in consideration of visibility, each member corresponds to the whole drawing by reference numerals.

  First, a negative electrode active material is mixed with a binder or filler used as desired in an organic solvent to prepare a slurry-like or paste-like negative electrode mixture. The obtained negative electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a negative electrode mixture layer. Further, the laminate of the current collector and the negative electrode composite material layer is rolled with a roll press or the like to prepare a predetermined thickness to obtain a negative electrode sheet (electrode sheet). At this time, the coating method of each agent, the drying of the coated material, and the method of forming the positive and negative electrodes may be in accordance with conventional methods.

  In the present embodiment, a cylindrical battery is taken as an example, but the present invention is not limited to this, for example, after the positive and negative electrode sheets produced by the above method are overlapped via a separator, After processing into a sheet battery as it is, or inserting it into a rectangular can after being folded and electrically connecting the can and the sheet, injecting an electrolyte and sealing the opening using a sealing plate A square battery may be formed.

  In any embodiment, the safety valve can be used as a sealing plate for sealing the opening. In addition to the safety valve, the sealing member may be provided with various conventionally known safety elements. For example, a fuse, bimetal, PTC element, or the like is preferably used as the overcurrent prevention element.

  In addition to the safety valve, as a countermeasure against the increase in the internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.

  For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are preferably used.

  As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

[Applications of non-aqueous secondary batteries]
The application mode of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when mounted on an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, Pager, handy terminal, portable fax, portable copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini-disc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio , Backup power supply, memory card and so on. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.

  The application mode of the electrolyte solution for a non-aqueous secondary battery of the present invention is not limited, but may be applied to applications that are expected to be used at high temperatures, particularly from the viewpoint of exhibiting the advantages of high-temperature storage stability and high-rate discharge characteristics. preferable. For example, it is assumed that an electric vehicle or the like is exposed to a high temperature outdoors in a charged state. In addition, an electric vehicle needs to be discharged at a high rate when starting and accelerating, and it is important that the high-rate discharge capacity does not deteriorate even when stored at a high temperature. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
<Example 1 and Comparative Example 1>
Preparation of Electrolyte Solution 1M LiBF ₄ ethylene carbonate / γ-butyrolactone volume ratio 3 to 7 electrolyte solution was added the components shown in Table 1 in the amounts shown in the table, and the electrolyte solution for Examples and Comparative Examples An electrolyte solution was prepared. All the prepared electrolyte solutions had a viscosity at 25 ° C. of 5 mPa · s or less.
<Confirmation of film formation>
Cyclic voltammetry measurements were performed on the test electrolytes shown in Table 1 in a beaker cell using a platinum plate of 10 mm × 10 mm and a thickness of 0.5 mm as a working electrode, a counter electrode, and a lithium metal foil as a reference electrode. . Sweeping was performed at a sweep rate of 1 mV / s to the potential corresponding to the charged negative electrode and the charged positive electrode, and the platinum plate of the working electrode was washed with DMC, and then the film formed on the platinum plate was confirmed with Varian microscopic IR.

<Notes on the table>
Test NO. : A comparative example starts with c.
Comp. : Compound No. Conc. : Concentration (M)
VC: Vinyl carbonate VEC: Vinyl ethylene carbonate EA: Ethyl acrylate

[Film check]
Yes indicates that the organic matter can be confirmed by FT-IR. No is an organic substance not confirmed by FT-IR.

<Example 2 and Comparative Example 2>
Preparation of Electrolyte 1M LiBF ₄ ethylene carbonate / γ-butyrolactone volume ratio 3 to 7 The electrolyte shown in Table 2 was added to the electrolyte in the amount shown in Table 2 in the amount shown in the table, and the electrolyte for Examples and Comparative Examples An electrolyte solution was prepared. All the prepared electrolyte solutions had a viscosity at 25 ° C. of 5 mPa · s or less.
<Production of battery (1)>
The positive electrode is made of active material: nickel manganese lithium cobaltate (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) 85% by mass, conductive auxiliary agent: carbon black 7% by mass, binder: PVDF 8% by mass, The negative electrode was prepared with 94% by mass of active material: lithium titanate (Li ₄ Ti ₅ O ₁₂ ), conductive auxiliary agent: 3% by mass of carbon black, and binder: 3% by mass of PVDF. The separator is made of cellulose and has a thickness of 40 μm. Using the above positive and negative electrodes and separator, a 2032 type coin battery was prepared for each test electrolyte, and the following items were evaluated. The results are shown in Table 2.

<High temperature cycle test>
After charging the 2032 type coin battery in a constant temperature bath at 45 ° C. until the battery voltage reaches 2.75 V, the current value becomes 0.12 mA at 2.75 V constant voltage, or charge for 2 hours. Then, 1C constant current discharge was performed until the battery voltage reached 1.2 V, and one cycle was obtained. This was repeated until 500 cycles were reached.
(High temperature capacity retention rate HTratio (%)) =
{(Discharge capacity at 500th cycle / Discharge capacity at 1st cycle)} × 100

<High rate discharge capacity maintenance rate>
In a constant temperature bath at 30 ° C., after charging with a constant current of 0.1 C until the battery voltage becomes 2.75 V, the current value becomes 0.06 mA at a constant voltage of 2.75 V, or charging is performed for 2 hours, and then the battery A 0.2 C constant current discharge was performed until the voltage reached 1.2 V, and the battery capacity was measured. Again, after charging with a constant current of 0.1 C until the battery voltage reaches 2.75 V, the current value becomes 0.06 mA at a constant voltage of 2.75 V, or after 2 hours of charging, the battery voltage becomes 1.2 V. 5C constant current discharge was performed until the high rate discharge capacity was measured. The high rate discharge capacity retention rate was calculated by the following formula. The larger the value, the better the discharge capacity deterioration at a high rate, even when charging and discharging are repeated.
(High rate discharge capacity maintenance rate HRratio (%)) =
{(5C discharge capacity) / (initial 0.2C discharge capacity)} × 100

<Notes on the table>
Test No. : A comparative example starts with c. Other than that, the invention example Comp. : Compound No. Conc. : Concentration (M)
From the above results, it can be seen that according to the nonaqueous electrolytic solution of the present invention, the capacity is suitably maintained even when stored at a high temperature, and the high rate discharge characteristics are excellent.

<Example 3 and Comparative Example 3>
A 2032 coin battery (2) was produced in the same manner as in Example 1 except that the following were used as the organic solvent for the electrolytic solution, the positive electrode / negative electrode active material, and the separator.
Organic solvent: ethylene carbonate / diethyl carbonate Volume ratio 1: 2
Positive electrode active material: lithium cobaltate (LiCoO ₂ )
Negative electrode active material: Graphite Separator: 25 μm thickness made of polypropylene <High temperature cycle test (HTratio)>
The evaluation was performed under the same conditions as the evaluation performed for the battery 1 except that the upper limit voltage during charging was 4.3 V and the lower limit voltage during discharge was 2.75 V.
<High rate discharge capacity maintenance rate (HRratio)>
The evaluation was performed under the same conditions as those of the battery 1 except that the upper limit voltage during charging was 4.3 V, the lower limit voltage during discharge was 2.75 V, and the high rate discharge was 4 C.

  From the above results, it can be seen that the non-aqueous electrolyte of the present invention achieves good performance even in different types of secondary batteries.

DESCRIPTION OF SYMBOLS 1 Positive electrode conductive material 2 Positive electrode active material 3 Negative electrode conductive material 4 Negative electrode active material 5 Electrolyte 6 Operation means 7 Wiring 9 Separator 10 Lithium ion secondary battery 12 Separator 14 Positive electrode sheet 16 Negative electrode sheet 18 The outer can 20 which also serves as a negative electrode Insulating plate 22 Sealing plate 24 Positive electrode current collector 26 Gasket 28 Pressure sensitive valve element 30 Current interrupting element 100 Bottomed cylindrical lithium secondary battery

Claims (11)

  An electrolytic solution for a non-aqueous secondary battery, which contains, in an organic solvent, a specific compound having a site that generates active species by electrolytic oxidation or electrolytic reduction in the molecule and a polymerizable site, and an electrolyte. The electrolyte solution for a non-aqueous secondary battery according to claim 1, wherein the specific compound is a compound represented by any one of the following formulas (1) to (3).

(In the formula, R ¹ represents an alkyl group or an aryl group. R ² and R ³ each represents a fluorine atom or an organic group. R ⁷ represents an alkyl group, a carbonyl group-containing group, an aryl group, or a heteroaryl group. R ^{8 to} R ¹¹ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and benzene ring A ¹ , R ⁷ and benzene ring A ² , and R ⁸ and R ⁹ are bonded to each other via a linking group. M represents a substituent having a polymerizable moiety, n1 represents an integer of 0 to 5, and n2 represents an integer of 0 to 4.)   The electrolyte solution for a non-aqueous secondary battery according to claim 1 or 2, wherein the polymerizable site is a substituent having a vinyl group, a styrene structure group, an acryloyl group, or a methacryloyl group. The specific compound is a compound represented by any one of the following formulas (1-1) to (1-3), (2-1), (2-2), and (3-1). The electrolyte solution for non-aqueous secondary batteries in any one of -3.

(Wherein R ² , R ³ , n1, n2, and M have the same meanings as in formulas (1) and (2). The benzene ring A ³ and the benzene ring A ⁴ are bonded to each other via a linking group. Examples of the linking group include a single bond, an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, and an amino linking group, wherein R ²¹ and R ²² are a hydrogen atom, an alkyl group, and an aryl group, respectively. X represents an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, or an amino linking group.)

(Wherein R ² , R ³ , n1, n2, and M have the same meanings as in formulas (1) and (2). The benzene rings A ⁵ and A ⁶ may be bonded to each other via a linking group. Examples of the linking group include a single bond, an alkylene group, an arylene group, an ether group, a thioether group, a carbonyl group, and an amino group (—NR—: R is a hydrogen atom or a substituent), and R ⁴ and R ⁵ are Each represents a hydrogen atom or an alkyl group, and Y represents an alkoxy group or an amino group.)

(In the formula, R ^{31 to} R ³⁴ each independently represent a hydrogen atom or an alkyl group. G independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an amino group. E represents a linking group. , An alkylene group, an ether group, an amino group (-NR-: R represents a hydrogen atom or a substituent), or a group obtained by combining these.) The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein the polymerizable site is a structural portion represented by any of the following formulas (M-1) to (M-3).

(In the formula, L represents a single bond, an alkylene group, an ester group, an ether group, a thioether group, or a combination thereof. * Represents ^a site bonded to the active species generating site. ^Ra represents ^a hydrogen atom or a substituent. R ^b represents a hydrogen atom or a substituent, and n4 represents an integer of 0 to 4.)   The electrolyte solution for nonaqueous secondary batteries according to any one of claims 1 to 5, comprising the specific compound in an amount of 0.0001 to 0.05 mol / L.   The secondary battery which comprises a positive electrode, a negative electrode, a separator, and the electrolyte solution in any one of Claims 1-6.   The secondary battery according to claim 7, wherein the active material of the positive electrode is made of a material having nickel, manganese, and cobalt.   The secondary battery according to claim 7 or 8, wherein the negative electrode active material is composed of lithium titanate.   Nonaqueous secondary battery electrolyte comprising a combination of a first agent containing an electrolyte and a second agent containing a specific compound having a site that generates active species by electrolytic oxidation or electrolytic reduction in the molecule and a polymerizable site For kit. The kit for nonaqueous secondary battery electrolyte solution according to claim 10, wherein the specific compound is a compound represented by any one of the following formulas (1) to (3).

(In the formula, R ¹ represents an alkyl group or an aryl group. R ² and R ³ each represents a fluorine atom or an organic group. R ⁷ represents an alkyl group, a carbonyl group-containing group, an aryl group, or a heteroaryl group. R ^{8 to} R ¹¹ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and benzene ring A ¹ , R ⁷ and benzene ring A ² , and R ⁸ and R ⁹ are bonded to each other via a linking group. M represents a substituent having a polymerizable moiety, n1 represents an integer of 0 to 5, and n2 represents an integer of 0 to 4.)

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