JP5071310B2 - Negative electrode composite and lithium secondary battery using the same - Google Patents

Description

  The present invention relates to a negative electrode mixture capable of producing an electrode in which a negative electrode active material is sufficiently dispersed and with little variation in thickness and density, a manufacturing method thereof, and a lithium secondary battery using the same.

  In recent years, small portable electronic devices such as digital cameras and mobile phones have been widely used. These electronic devices have always been required to minimize the volume and reduce the weight, and the batteries to be mounted are also required to be small, light, and have a large capacity. Also, in large-sized secondary batteries for automobiles and the like, it is desired to realize a large non-aqueous electrolyte secondary battery instead of a conventional lead-acid battery.

  In order to meet such demands, lithium secondary batteries are being actively developed. As an electrode of a lithium secondary battery, a positive electrode in which an electrode mixture composed of a positive electrode active material containing lithium ions, a conductive additive, an organic binder, and the like is fixed to the surface of a current collector of metal foil, and lithium ion desorption. A negative electrode is used in which an electrode mixture made of an insertable negative electrode active material, a conductive additive, an organic binder, and the like is fixed to the surface of a current collector made of metal foil.

  In general, carbon-based materials such as graphite, antimony-based, tin-based, and silicon-based alloy materials, metal oxide materials such as lithium titanate, and the like are used as the negative electrode active material. In preparing the negative electrode mixture layer, if the dispersion of these negative electrode active materials is insufficient, coarse aggregate remaining on the electrode sheet, the aggregate will be lost and cause coating film defects, etc. There may be a problem that a uniform electrode film cannot be formed.

  In addition, when coarse aggregated particles are present, when charging and discharging are repeated many times, the adhesion at the interface between the current collector and the negative electrode mixture layer is deteriorated, and the battery performance may be deteriorated. This is the case when local shear stress occurs between the electrode mixture layer and the current collector interface due to repeated expansion and contraction of the active material and electrode mixture layer due to lithium ion doping and dedoping during charging and discharging. It is considered that one of the causes is that the adhesiveness at the interface deteriorates because the stress is not easily relieved by the aggregated particles.

  In order to solve such a problem, Patent Document 1 discloses a method of preparing a composite material containing an active material by kneading with a kneader. However, it seems difficult to obtain excellent dispersibility and dispersion stability simply by physical kneading with a kneader.

  Patent Document 2 discloses a method for improving the dispersibility of the negative electrode active material by swelling and thickening a styrene butadiene rubber as a binder with an organic solvent. In this case, the thickening effect of the composite paste can be expected, but it seems difficult to sufficiently disaggregate the negative electrode active material and stabilize the dispersion.

  Patent Document 3 discloses a method of dispersing and kneading a negative electrode active material by adding a surfactant. However, in order to obtain good dispersibility and dispersion stability with a surfactant, the amount of addition must be increased, resulting in a decrease in the active material concentration in the electrode, resulting in a decrease in battery capacity. I think that. Furthermore, there is a possibility that doping and dedoping of lithium ions may be inhibited by covering the negative electrode active material with a surfactant.

Patent Document 4 discloses a method of dispersing a carbon-based negative electrode active material using a polymer dispersant. However, even in this case, the same problem as in Patent Document 3 may occur.
JP-A-7-29605 JP 2007-234418 A JP-A-8-190912 JP-T-2006-51679 gazette

  In view of the above problems, the present invention improves the dispersibility and dispersion stability of a negative electrode active material, and can form a uniform negative electrode active material filled with a negative electrode active material at a high density. An object is to provide a lithium secondary battery used.

The negative electrode mixture of the present invention contains at least one selected from an organic dye derivative having a basic functional group or a triazine derivative having a basic functional group as a dispersant, and at least selected from the following group A or group B: It contains a kind of negative electrode active material.
(Group A: Mesophase carbon, spheroidal graphite, lithium titanate and lithium vanadium oxide Group B: Carbon which is at least one selected from the group consisting of mesophase carbon, lithium titanate, lithium vanadium oxide and silicon powder is a conductive substance Negative electrode active material combined with materials)

The present invention also provides a lithium battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium. The present invention relates to a lithium secondary battery, wherein a composite material layer is formed using the negative electrode composite material.

  The negative electrode composite of the present invention can greatly reduce the aggregates of the negative electrode active material, hardly re-aggregates, and is excellent in storage stability. By using the negative electrode mixture of the present invention for a lithium battery, it is possible to produce an electrode film that is uniformly filled with an active material at a high density.

  First, the material contained in the negative electrode composite of the present invention will be described.

<Dispersant>
The dispersant in the present invention is selected from the group consisting of organic dye derivatives having basic functional groups, anthraquinone derivatives having basic functional groups, acridone derivatives having basic functional groups, and triazine derivatives having basic functional groups. It is what
In particular, the use of a triazine derivative represented by the following general formula (1) or an organic dye derivative represented by the general formula (6) is preferable.

  General formula (1)

Ｘ_１は、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ_２ＮＨ−、−ＣＨ_２ＮＨ−、−ＣＨ_２ＮＨＣＯＣＨ_２ＮＨ−または−Ｘ_２−Ｙ−Ｘ_３−を表し、Ｘ_２は、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ_２ＮＨ−、−ＣＨ_２ＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ_２−を表し、Ｘ_３はそれぞれ独立に−ＮＨ−または、−Ｏ−を表し、Ｙは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または、置換基を有してもよいアリーレン基を表す。
Ｐは、一般式（２）、（３）または、一般式(４)のいずれかで示される置換基を表す。
Ｑは、−Ｏ−Ｒ_２、−ＮＨ−Ｒ_２、ハロゲン基、−Ｘ_１−Ｒ_１または、一般式（２）、（３）もしくは、一般式(４)のいずれかで示される置換基を表す。
Ｒ_２は、水素原子、置換基を有してもよいアルキル基または、置換基を有してもよいアルケニル基もしくは、置換基を有してもよいアリール基を表す。

X _{1 is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or _-X 2 _{-Y-X 3} - represents, _{X 2 is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - NHCO- or -NHSO ₂ - represents, _{X 3} each independently -NH- or, -O -Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, which is composed of 1 to 20 carbon atoms. To express.
P represents a substituent represented by any one of the general formulas (2), (3) or the general formula (4).
Q is —O—R ₂ , —NH—R ₂ , a halogen group, —X ₁ —R _1, or a substituent represented by any one of the general formulas (2), (3), or (4) Represents.
R ₂ represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or an aryl group that may have a substituent.

General formula (2)

General formula (3)

General formula (4)

Ｘ_４は、直接結合、−ＳＯ₂−、−ＣＯ−、−ＣＨ₂ＮＨＣＯＣＨ₂−、−ＣＨ₂ＮＨＣＯＮＨＣＨ₂−、−ＣＨ₂−または、−Ｘ_５−Ｙ−Ｘ_６−を表す。Ｘ_５は、−ＮＨ−または、−Ｏ−を表し、Ｘ_６は、直接結合、−ＳＯ₂−、−ＣＯ−、−ＣＨ₂ＮＨＣＯＣＨ₂−、−ＣＨ₂ＮＨＣＯＮＨＣＨ₂−または、−ＣＨ₂−を表す。Ｙは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または、置換基を有してもよいアリーレン基を表す。
ｖは、１〜１０の整数を表す。
Ｒ_３ 、Ｒ_４はそれぞれ独立に、水素原子、置換されていてもよいアルキル基、置換されていてもよいアルケニル基、置換されていてもよいアリール基、またはＲ_３ 、Ｒ_４とで一体となって更なる窒素、酸素または硫黄原子を含む置換されていてもよい複素環残基を表す。とりわけ、水素原子であることが、電池内での金属析出を抑える効果が高いと思われ好ましい。
Ｒ_５ 、Ｒ_６ 、Ｒ_７ 、Ｒ_８は、それぞれ独立に、水素原子、置換されていてもよいアルキル基、置換されていてもよいアルケニル基または置換されていてもよいアリール基を表す。
Ｒ_９は、置換されていてもよいアルキル基、置換されていてもよいアルケニル基または置換されていてもよいアリール基を表す。
ｎは、１〜４の整数を表す。
Ｒ_１は有機色素残基、置換基を有していてもよい複素環残基、置換基を有していてもよい芳香族環残基または下記一般式（５）で示される基を表す。

X ₄ is a direct _{bond, -SO 2 -, - CO -} , - CH 2 NHCOCH 2 -, - CH 2 NHCONHCH 2 -, - CH 2 - _or, -X 5 _{-Y-X 6} - represents a. X ₅ is -NH- or represents -O-, _{X 6} represents a direct _{bond, -SO 2 -, - CO -} , - CH 2 NHCOCH 2 -, - CH 2 NHCONHCH 2 - or -CH ₂ - Represents. Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, having 1 to 20 carbon atoms.
v represents an integer of 1 to 10.
R ₃ and R ₄ are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group, or R ₃ and R _4. Represents an optionally substituted heterocyclic residue containing additional nitrogen, oxygen or sulfur atoms. In particular, a hydrogen atom is preferable because it is considered that the effect of suppressing metal deposition in the battery is high.
R ₅ , R ₆ , R ₇ and R ₈ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group or an optionally substituted aryl group.
R ₉ represents an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.
n represents an integer of 1 to 4.
R ₁ represents an organic dye residue, a heterocyclic residue which may have a substituent, an aromatic ring residue which may have a substituent, or a group represented by the following general formula (5).

  General formula (5)

Ｔは、−Ｘ_８−Ｒ_１０または、Ｗ_１を表し、Ｕは、−Ｘ_９−Ｒ_１１または、Ｗ_２を表す。
Ｗ_１およびＷ_２は、それぞれ独立に−Ｏ−Ｒ_２、−ＮＨ−Ｒ_２、ハロゲン基または、一般式（２）、（３）もしくは、一般式(４)のいずれかで示される置換基を表す。
Ｒ_２は、水素原子、置換基を有してもよいアルキル基または、置換基を有してもよいアルケニル基もしくは、置換基を有してもよいアリール基を表す。
Ｘ_７は−ＮＨ−または−Ｏ−を表し、Ｘ_８およびＸ_９は、それぞれ独立に−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ_２ＮＨ−、−ＣＨ_２ＮＨ−または−ＣＨ_２ＮＨＣＯＣＨ_２ＮＨ−を表す。
Ｙは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または、置換基を有してもよいアリーレン基を示す。
Ｒ_１０およびＲ_１１はそれぞれ独立に、有機色素残基、置換基を有していてもよい複素環残基、置換基を有していてもよい芳香族環残基を表す。

T _is -X 8 _{-R 10} or represents _{W 1,} U _represents -X 9 _{-R 11} or _{W 2.}
W ₁ and W ₂ are each independently —O—R ₂ , —NH—R ₂ , a halogen group, or a substituent represented by any one of the general formulas (2), (3), and (4). Represents.
R ₂ represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or an aryl group that may have a substituent.
X ₇ represents an -NH- or -O-, _{X 8} and _{X 9} are each independently -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH- or -CH ₂ NHCOCH ₂ NH— is represented.
Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, which has 1 to 20 carbon atoms.
R ₁₀ and R ₁₁ each independently represents an organic dye residue, a heterocyclic residue which may have a substituent, or an aromatic ring residue which may have a substituent.

Examples of the organic dye residue represented by R _{1 in the} general formula (1) and R ₁₀ and R ₁₁ in the general formula (5) include azo dyes such as diketopyrrolopyrrole dyes, azo, disazo, and polyazo. Anthraquinone dyes such as phthalocyanine dyes, diaminodianthraquinones, anthrapyrimidines, flavantrons, anthanthrones, indantrons, pyrantrons, violanthrones, quinacridone dyes, dioxazine dyes, perinone dyes, perylene dyes, thioindigo dyes And dyes, isoindoline dyes, isoindolinone dyes, quinophthalone dyes, selenium dyes, metal complex dyes, and the like. In particular, in order to enhance the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye residue that is not a metal complex dye.

Examples of the heterocyclic residue and aromatic ring residue represented by R _{1 in the} general formula (1) and R ₁₀ and R ₁₁ in the general formula (5) include thiophene, furan, pyridine, pyrazine, triazine, Examples include pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, benzthiazole, benztriazole, indole, quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, and acridone. These heterocyclic residues and aromatic ring residues are alkyl groups (methyl group, ethyl group, butyl group, etc.), amino groups, alkylamino groups (dimethylamino group, diethylamino group, dibutylamino group, etc.), nitro groups. Hydroxyl group, alkoxy group (methoxy group, ethoxy group, butoxy group, etc.), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) And a substituent such as a phenylamino group (which may be substituted with an alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) May be.

Y in the general formulas (1) and (5) represents an alkylene group, an alkenylene group or an arylene group which may have a substituent having 20 or less carbon atoms, and preferably an optionally substituted phenylene. Group, biphenylene group, naphthylene group or alkylene group which may have a side chain having 10 or less carbon atoms.
General formula (6)

Ｚは、下記一般式（７）、（８）または、一般式（９）で示される群から選ばれる少なくとも１つのものである。ｎは、１〜４の整数を表す。
一般式（７）

Z is at least one selected from the group represented by the following general formula (7), (8) or general formula (9). n represents an integer of 1 to 4.
General formula (7)

General formula (8)

一般式（９）

General formula (9)

Ｘ_４は、直接結合、−ＳＯ₂−、−ＣＯ−、−ＣＨ₂ＮＨＣＯＣＨ₂−、−ＣＨ₂ＮＨＣＯＮＨＣＨ₂−、−ＣＨ₂−または、−Ｘ_５−Ｙ−Ｘ_６−を表す。Ｘ_５は、−ＮＨ−または、−Ｏ−を表し、Ｘ_６は、直接結合、−ＳＯ₂−、−ＣＯ−、−ＣＨ₂ＮＨＣＯＣＨ₂−、−ＣＨ₂ＮＨＣＯＮＨＣＨ₂−または、−ＣＨ₂−を表す。Ｙは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または、置換基を有してもよいアリーレン基を表す。
ｖは、１〜１０の整数を表す。
Ｒ_３ 、Ｒ_４はそれぞれ独立に、水素原子、置換されていてもよいアルキル基、置換されていてもよいアルケニル基、置換されていてもよいフェニル基、またはＲ_３ 、Ｒ_４とで一体となって更なる窒素、酸素または硫黄原子を含む置換されていてもよい複素環残基を表す。とりわけ、水素原子であることが、電池内での金属析出を抑える効果が高いと思われ好ましい。
Ｒ_５ 、Ｒ_６ 、Ｒ_７ 、Ｒ_８は、それぞれ独立に、水素原子、置換されていてもよいアルキル基、置換されていてもよいアルケニル基または置換されていてもよいアリール基を表す。
Ｒ_９は、置換されていてもよいアルキル基、置換されていてもよいアルケニル基または置換されていてもよいアリール基を表す。
Ｒ_１２は有機色素残基、置換基を有していてもよい複素環残基、置換基を有していてもよい芳香族環残基す。

X ₄ is a direct _{bond, -SO 2 -, - CO -} , - CH 2 NHCOCH 2 -, - CH 2 NHCONHCH 2 -, - CH 2 - _or, -X 5 _{-Y-X 6} - represents a. X ₅ is -NH- or represents -O-, _{X 6} represents a direct _{bond, -SO 2 -, - CO -} , - CH 2 NHCOCH 2 -, - CH 2 NHCONHCH 2 - or -CH ₂ - Represents. Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, having 1 to 20 carbon atoms.
v represents an integer of 1 to 10.
R ₃ and R ₄ are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted phenyl group, or R ₃ and R _4. Represents an optionally substituted heterocyclic residue containing additional nitrogen, oxygen or sulfur atoms. In particular, a hydrogen atom is preferable because it is considered that the effect of suppressing metal deposition in the battery is high.
R ₅ , R ₆ , R ₇ and R ₈ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group or an optionally substituted aryl group.
R ₉ represents an optionally substituted alkyl group, an optionally substituted alkenyl group, or an optionally substituted aryl group.
R ₁₂ is an organic dye residue, a heterocyclic residue which may have a substituent, or an aromatic ring residue which may have a substituent.

Examples of the organic dye residue represented by R ₁₂ include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, and polyazo, phthalocyanine dyes, diaminodianthraquinone, anthrapyrimidine, flavantrons, anthanthrones, and indans. Anthraquinone dyes such as throne, pyranthrone, violanthrone, quinacridone dyes, dioxazine dyes, perinone dyes, perylene dyes, thioindigo dyes, isoindoline dyes, isoindolinone dyes, quinophthalone dyes, sulene dyes Examples thereof include dyes and metal complex dyes. In particular, in order to enhance the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye residue that is not a metal complex dye.

Examples of the heterocyclic residue and aromatic ring residue represented by R ₁₂ include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, benzthiazole, benzine. Examples include triazole, indole, quinoline, carbazole, acridine, benzene, naphthalene, anthracene, fluorene, phenanthrene, anthraquinone, acridone and the like. These heterocyclic residues and aromatic ring residues are alkyl groups (methyl group, ethyl group, butyl group, etc.), amino groups, alkylamino groups (dimethylamino group, diethylamino group, dibutylamino group, etc.), nitro groups. Hydroxyl group, alkoxy group (methoxy group, ethoxy group, butoxy group, etc.), halogen (chlorine, bromine, fluorine, etc.), phenyl group (alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) And a substituent such as a phenylamino group (which may be substituted with an alkyl group, amino group, alkylamino group, nitro group, hydroxyl group, alkoxy group, halogen, etc.) May be.

  Examples of the amine component used for forming the substituents represented by the general formulas (2) to (4) and the general formulas (6) to (8) include dimethylamine, diethylamine, methylethylamine, N, N-ethylisopropylamine, N, N-ethylpropylamine, N, N-methylbutylamine, N, N-methylisobutylamine, N, N-butylethylamine, N, N-tert-butylethylamine, diisopropylamine, dipropyl Amine, N, N-sec-butylpropylamine, dibutylamine, di-sec-butylamine, diisobutylamine, N, N-isobutyl-sec-butylamine, diamylamine, diisoamylamine, dihexylamine, dicyclohexylamine, di (2- Ethylhexyl) amine, dioctylami N, N-methyloctadecylamine, didecylamine, diallylamine, N, N-ethyl-1,2-dimethylpropylamine, N, N-methylhexylamine, dioleylamine, distearylamine, N, N-dimethylaminomethylamine N, N-dimethylaminoethylamine, N, N-dimethylaminoamylamine, N, N-dimethylaminobutylamine, N, N-diethylaminoethylamine, N, N-diethylaminopropylamine, N, N-diethylaminohexylamine, N , N-diethylaminobutylamine, N, N-diethylaminopentylamine, N, N-dipropylaminobutylamine, N, N-dibutylaminopropylamine, N, N-dibutylaminoethylamine, N, N-dibutylaminobutylamine, N N-diisobutylaminopentylamine, N, N-methyl-laurylaminopropylamine, N, N-ethyl-hexylaminoethylamine, N, N-distearylaminoethylamine, N, N-dioleylaminoethylamine, N, N- Distearylaminobutylamine, piperidine, 2-pipecoline, 3-pipecoline, 4-pipecoline, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, 3-piperidinemethanol, pipecolic acid, isonipecotic acid, isonicopetin Methyl acid, ethyl isonicopetinate, 2-piperidineethanol, pyrrolidine, 3-hydroxypyrrolidine, N-aminoethylpiperidine, N-aminoethyl-4-pipecoline, N-aminoethylmorpholine, N-aminopropylpiperidine, N-amino Propyl-2-pipecholine, N-aminopropyl-4-pipecoline, N-aminopropylmorpholine, N-methylpiperazine, N-butylpiperazine, N-methylhomopiperazine, 1-cyclopentylpiperazine, 1-amino-4-methylpiperazine 1-cyclopentylpiperazine and the like.

  The method for synthesizing the organic dye derivative, anthraquinone derivative and acridone derivative having a basic functional group and the triazine derivative having a basic functional group of the present invention is not particularly limited, but JP-A-54-62227. JP, 56-118462, JP 56-166266, JP 60-88185, JP 63-305173, JP 3-2676, JP 11-11 It can be synthesized by the method described in 199796.

For example, after introducing substituents represented by the formulas (10) to (13) into an organic dye, anthraquinone, or acridone, these substituents and amine components (for example, N, N-dimethylaminopropylamine, N-methyl) It can be synthesized by reacting piperazine, diethylamine or 4- [4-hydroxy-6- [3- (dibutylamino) propylamino] -1,3,5-triazin-2-ylamino] aniline, etc.) .
Formula (10) _-SO 2 Cl
Formula (11) -COCl
Equation ₍₁₂₎ -CH ₂ NHCOCH 2 Cl
Equation (13) _-CH 2 Cl
For example, when introducing the substituent represented by the formula (10), an organic dye, anthraquinone, or acridone is dissolved in chlorosulfonic acid and reacted with a chlorinating agent such as thionyl chloride. The number of substituents represented by the formula (10) to be introduced into the organic dye, anthraquinone, or acridone can be controlled by conditions such as the reaction temperature and reaction time.

  In addition, when introducing the substituent represented by the formula (11), first, an organic dye having a carboxyl group, anthraquinone, or acridone is synthesized by a known method, and then thionyl chloride or the like in an aromatic solvent such as benzene. And the like, and the like.

  During the reaction between the substituent represented by formula (10) to formula (13) and the amine component, a part of the substituent represented by formula (10) to formula (13) is hydrolyzed, and chlorine is substituted with a hydroxyl group. There are things to do. In that case, the substituent represented by the formula (10) is a sulfonic acid group, and the substituent represented by the formula (11) is a carboxylic acid group. A metal or a salt of the above amine may be formed.

  When the organic dye is an azo dye, a substituent represented by formula (7) to formula (9) or the following general formula (14) is previously introduced into the diazo component or coupling component, and then coupled. An azo organic dye derivative can also be produced by carrying out the reaction.

General formula (14)

Ｘ_１は、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ_２ＮＨ−、−ＣＨ_２ＮＨ−、−ＣＨ_２ＮＨＣＯＣＨ_２ＮＨ−または−Ｘ_２−Ｙ−Ｘ_３−を表し、Ｘ_２は、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ_２ＮＨ−、−ＣＨ_２ＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ_２−を表し、Ｘ_３はそれぞれ独立に−ＮＨ−または−Ｏ−を表し、Ｙは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基、置換基を有してもよいアルケニレン基または、置換基を有してもよいアリーレン基を表す。
Ｐは、一般式（２）、（３）または、一般式(４)のいずれかで示される置換基を表す。
Ｑは、−Ｏ−Ｒ_２、−ＮＨ−Ｒ_２、ハロゲン基、−Ｘ_１−Ｒ_１または、一般式（２）、（３）もしくは、一般式(４)のいずれかで示される置換基を表す。
Ｒ_２は、水素原子、置換基を有してもよいアルキル基または、置換基を有してもよいアルケニル基もしくは、置換基を有してもよいアリール基を表す。

X _{1 is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or _-X 2 _{-Y-X 3} - represents, _{X 2 is, -NH -, - O -,} - CONH -, - SO 2 NH -, - CH 2 NH -, - NHCO- or -NHSO ₂ - represents, _{X 3} each independently -NH- or -O- Y represents an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or an arylene group which may have a substituent, which is composed of 1 to 20 carbon atoms. .
P represents a substituent represented by any one of the general formulas (2), (3) or the general formula (4).
Q is —O—R ₂ , —NH—R ₂ , a halogen group, —X ₁ —R _1, or a substituent represented by any one of the general formulas (2), (3), or (4) Represents.
R ₂ represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or an aryl group that may have a substituent.

  The triazine derivative having a basic functional group of the present invention is represented by, for example, cyanuric chloride as a starting material, and at least one chlorine of cyanuric chloride represented by formula (7) to formula (9) or general formula (14). It is obtained by reacting an amine component (for example, N, N-dimethylaminopropylamine or N-methylpiperazine etc.) that forms a substituent, and then reacting the remaining chlorine of cyanuric chloride with various amines or alcohols. It is done.

  The dispersant of the present invention is considered to exhibit a dispersion effect when the added dispersant acts (for example, adsorbs) on the surface of the negative electrode active material. One or more kinds selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group are completely contained in a solvent. It is thought that the action of these dispersants on the negative electrode active material progresses by dissolving or partially dissolving the negative electrode active material in the solution. The basic functional group of the dispersant acting on the surface of the negative electrode active material is polarized or dissociated, thereby inducing an electrical interaction (repulsion effect) and causing the deagglomeration of the negative electrode active material. Seem. Therefore, in the present invention, a good dispersion state can be obtained without directly introducing (covalently bonding) a functional group to the surface of the negative electrode active material material and without using a dispersion resin. For these reasons, a good dispersion state can be obtained without degrading the performance of the negative electrode active material. By using the negative electrode mixture of the present invention in which the negative electrode active material is well dispersed, an electrode with high uniformity can be produced.

  In addition, in the electrode using the negative electrode mixture of the present invention, the presence of a dispersant having a polar functional group on the surface of the negative electrode active material improves the wettability of the negative electrode active material to the electrolytic solution, and Combined with the uniform dispersion effect, the wettability of the electrode to the electrolyte is improved.

  It is preferable to add an acidic compound as a dispersion aid to the negative electrode mixture of the present invention. The acidic compound used at this time is not particularly limited, but includes hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, salts of inorganic compounds obtained by the reaction of strong acids and weak bases, organic acids such as carboxylic acids, phosphoric acids, and sulfonic acids. Can be used. Among them, it is preferable to use an acid that decomposes or volatilizes in the drying step at the time of electrode preparation, and it is preferable to use an acid having a molecular weight of 300 or less, preferably 200 or less. Further, it is preferable to use an acid having low reactivity with the electrode active material described later, and organic acids, particularly carboxylic acids are particularly preferable. Specifically, for example, formic acid, ethanoic acid (acetic acid), fluoroacetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, acrylic acid, methacrylic acid, Examples include crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and the like.

  These acids are one or more bases selected from organic dye derivatives having basic functional groups, anthraquinone derivatives having basic functional groups, acridone derivatives having basic functional groups, or triazine derivatives having basic functional groups. And the like (for example, formation of ion pairs by neutralization (salt formation), polarization or dissociation of ion pairs (salts), etc.), thereby increasing the solubility of these dispersants. Electrical interaction (for example, electrostatic repulsion between dispersant cations adsorbed on the surface of a carbon material, and repulsion by an electric double layer formed by dissociated acid anions) It is considered that deagglomeration of the negative electrode active material is promoted. The addition of these acids is also expected to suppress deterioration due to the dehydrofluorination reaction of the binder by acidification of the system when a polyvinylidene fluoride binder described later is used.

<Negative electrode active material>
The negative electrode active material used in the present invention is not particularly limited as long as it can be doped or intercalated with lithium ions. For example, metal Li, alloys thereof such as tin alloy, silicon alloy, lead alloy, Li _X Fe ₂ O ₃ , Li _X Fe ₃ O ₄ , Li _X WO ₂ , lithium titanate, lithium vanadate, silicon Metal oxides such as lithium oxide, conductive polymers such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon and hard carbon, artificial graphite such as highly graphitized carbon materials, or natural Examples thereof include carbonaceous powders such as graphite, carbon black, mesophase carbon black, resin-fired carbon materials, air-growth carbon fibers, and carbon fibers.
These negative electrode active materials can be used alone or in combination.

  As the negative electrode active material used in the present invention, a composite material made of a conductive material is also preferably used. Examples of the conductive substance include a carbon material, a conductive polymer material, a metal, and the like. In consideration of the interaction with the dispersant of the present invention, a carbon material or a conductive polymer material is preferable.

Examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, and polyphenylene derivatives. Carbonaceous materials include graphite such as natural graphite (scale-like graphite), artificial graphite, expanded graphite, etc., acetylene black, ketjen black, channel black, furnace black, lamp black as amorphous carbon, Carbon blacks such as thermal black, and carbon nanotubes, carbon nanofibers and the like are mentioned as fibrous carbon materials. Examples of the metal include Al, Ti, Fe, Ni, Cu, Zn, Ag, and Sn.
These complexing processes may be performed in combination of a plurality as required.

  As a method of compositing the negative electrode active material with a conductive material, for example, in the case of compositing a carbon material and a metal, mechanofusion, hybridization treatment and the like described in JP-A No. 2003-308845, Japanese Patent No. 3985263, etc. In the case of compounding a conductive polymer material and a conductive polymer material, a method of dipping in an organic solvent solution in which a conductive polymer is dissolved as described in JP-A-2001-68096, followed by drying and heat treatment Etc. Furthermore, a thermal decomposition product coating method of an organic substance by a CVD method, a formation method of a coating layer on an active material surface using a plasma method, and the like are also included. As other methods for coating the surface of the active material particles with a conductive material, a method using a binder and surface adsorption using frictional charging generated when powders dispersed in a gas phase come into contact with each other are used. The method of performing etc. can also be used.

  In addition, for metal-based, metal oxide-based negative electrode active materials, or metal-based negative electrode active materials, a coupling agent such as a silane coupling agent is considered in consideration of the interaction with the dispersant used in the present invention. It is also possible to treat the surface with

<Conductive aid>
Examples of the conductive additive used in the negative electrode mixture of the present invention include carbon materials, metals that are difficult to alloy with lithium, conductive polymer materials, and the like, and carbon materials are preferred. The carbon material is not particularly limited as long as it is a conductive carbon material, but graphite, carbon black, carbon nanotube, carbon nanofiber, carbon fiber, fullerene, etc. alone or in combination of two or more. Can be used.

  Carbon black used as a conductive aid can also be oxidized carbon. The oxidation treatment of carbon is performed by treating carbon at a high temperature in the air or by secondary treatment with nitric acid, nitrogen dioxide, ozone, etc., for example, such as phenol group, quinone group, carboxyl group, carbonyl group. This is a treatment for directly introducing (covalently bonding) an oxygen-containing polar functional group to the carbon surface, and is generally performed to improve the dispersibility of carbon. However, since it is common for the conductivity of carbon to fall, so that the introduction amount of a functional group increases, it is preferable to use the carbon which has not been oxidized.

Examples of commercially available carbon black include
Tokai Carbon furnace blacks such as Toka Black # 4300, # 4400, # 4500, and # 5500; Furnace Blacks manufactured by Degussa such as Printex L; Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, Conductex SC ULTRA, 975 ULTRA Furnace Black manufactured by Colombian, such as PUER BLACK 100, 115, and 205; Furnace manufactured by Mitsubishi Chemical, such as # 2350, # 2400B, # 2600B, # 30050B, # 3030B, # 3230B, # 3350B, # 3400B, and # 5400B Black; Cabot furnaces such as MONARCH1400, 1300, 900, VulcanXC-72R, and BlackPearls2000 Suba black; Furnace black made by TIMCAL such as Ensaco 250G, Ensaco 260G, Ensaco 350G, and SuperP-Li; Ketjen black made by Akzo such as Ketjen Black EC-300J and EC-600JD; and Denka Black, Denka Black HS- Examples thereof include acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd. such as 100 and FX-35, but are not limited thereto.

<Binder component>
The negative electrode mixture of the present invention preferably further contains a binder component. As binders to be used, ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, acrylonitrile, styrene, vinyl butyral, vinyl acetal, vinyl pyrrolidone, etc. Polymer or copolymer contained as structural unit, polyurethane resin, polyimide resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, acrylic resin, formaldehyde resin, silicon resin, polyvinylidene fluoride And fluorine resins such as polytetrafluoroethylene, cellulose resins such as carboxymethylcellulose, rubbers such as styrene-butadiene rubber and fluororubber, polyaniline, polyethylene Conductive resins such as acetylene and the like. Moreover, the modified body and mixture of these resin, and a copolymer may be sufficient.

  Among these binder resins, polymer fine particles and water-soluble polymers such as styrene butadiene rubber (SBR), polyacrylate, and polyurethane that can be used in water are preferable. These water-based fine-particle polymers and water-soluble polymers simplify the electrode manufacturing process, such as the absence of explosion-proof equipment and solvent recovery equipment, compared to organic solvent systems such as those used in systems such as polyvinylidene fluoride (PVDF). There are benefits.

  Among the above water-based binders, styrene butadiene rubber (SBR) is preferably used. Since SBR can be used in a smaller amount than a fluororesin binder such as polyvinylidene fluoride (PVDF), the capacity can be increased.

  Further, the negative electrode composite of the present invention can contain a thickener as necessary. In particular, when using a binder in which polymer fine particles such as SBR are dispersed, it may not be possible to impart good fluidity to the coating as it is, so the addition of a thickener is necessary. May be. Examples of the thickener include polyacrylic acid, polyethylene oxide, carboxymethyl cellulose, and the like. Among these, carboxymethyl cellulose is preferable.

<Solvent>
Examples of the solvent used in the negative electrode mixture of the present invention include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, and carboxylic acids. Examples include esters, phosphate esters, ethers, nitriles, water and the like.

  Considering the dispersibility of the negative electrode active material, it is preferable to use a polar solvent having a relative dielectric constant of 15 or more. The relative dielectric constant is one of the indices indicating the strength of the polarity of the solvent, and is described in Asahara et al., “Solvent Handbook” (Kodansha Scientific Co., Ltd., 1990).

  For example, methyl alcohol (dielectric constant: 33.1), ethyl alcohol (23.8), 2-propanol (18.3), 1-butanol (17.1), 1,2-ethanediol (38.66) ), 1,2-propanediol (32.0), 1,3-propanediol (35.0), 1,4-butanediol (31.1), diethylene glycol (31.69), 2-methoxyethanol ( 16.93), 2-ethoxyethanol (29.6), 2-aminoethanol (37.7), acetone (20.7), methyl ethyl ketone (18.51), formamide (111.0), N-methylformamide (182.4), N, N-dimethylformamide (36.71), N-methylacetamide (191.3), N, N-dimethylacetamide (3 .78), N-methylpropionamide (172.2), N-methylpyrrolidone (32.0), hexamethylphosphoric triamide (29.6), dimethyl sulfoxide (48.9), sulfolane (43.3), acetonitrile (37.5), propionitrile (29.7), water (80.1), and the like, but are not limited thereto.

In particular, the use of a polar solvent having a relative dielectric constant of 15 or more and 200 or less, preferably 15 or more and 100 or less, and more preferably 20 or more and 100 or less provides good dispersion stability of the negative electrode active material. Is preferable.
Solvents with a relative dielectric constant of less than 15 often have a significant decrease in the solubility of the dispersant, and good dispersion cannot be obtained. Is often not obtained.

  Among these solvents, as described above, water that can simplify the negative electrode manufacturing process is preferable.

<Composition>
The proportion of the negative electrode active material in the total solid content of the negative electrode mixture is desirably 80% by weight or more and 98.5% by weight or less. If the proportion of the negative electrode active material is less than 80% by weight, it may be difficult to obtain sufficient electrical conductivity and discharge capacity. If the proportion exceeds 98.5% by weight, the proportion of the binder component is reduced. In some cases, the adhesion to the body is lowered, and the negative electrode active material is easily detached.

  In addition, the ratio of the solid content of the conductive additive to the total solid content in the negative electrode mixture is 0.5 wt% or more and 19 wt% or less, preferably 1.0 wt% or more and 15 wt% or less. It is desirable to do. If the proportion of the conductive assistant is less than 0.5% by weight, it may be difficult to obtain sufficient conductivity. If the proportion is more than 19% by weight, the proportion of the positive electrode active material that greatly contributes to battery performance decreases. For this reason, problems such as a decrease in discharge capacity may occur.

  Moreover, the ratio of the binder component in the total solid content in the negative electrode mixture is preferably 1% by weight or more and 10% by weight or less. When the ratio of the binder component is less than 1% by weight, the binding property is lowered, so that the negative electrode active material, the carbon material as the conductive auxiliary agent, and the like may be easily detached from the current collector, which exceeds 10% by weight. And the ratio of the carbon material as a negative electrode active material and a conductive support agent falls, and it may lead to the fall of battery performance.

  Further, the appropriate viscosity of the negative electrode mixture depends on the coating method, but generally it is preferably 100 mPa · s or more and 30,000 mPa · s or less.

<Manufacturing method>
Next, the manufacturing method of the negative electrode composite material of this invention is demonstrated.

  The negative electrode composite of the present invention is, for example, selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group. It can be produced by dispersing at least one type of dispersant and a negative electrode active material in a solvent, and if necessary, mixing a carbon material and a binder as a conductive aid with the dispersion. The order of addition of each component is not limited to this. Moreover, you may add a solvent further as needed. When dispersing various derivatives having a basic functional group and the negative electrode active material in a solvent, it is more preferable to use an acidic compound together because dispersibility is improved.

  The production method includes at least one dispersant selected from organic dye derivatives having basic functional groups, anthraquinone derivatives having basic functional groups, acridone derivatives having basic functional groups, and triazine derivatives having basic functional groups. Is completely or partially dissolved in a solvent, and the negative electrode active material is added and mixed in the solution, whereby the derivative is dispersed in the solvent while acting (for example, adsorbing) on the negative electrode active material. The concentration of the negative electrode active material in the dispersion at this time is 1% by weight or more and 90% by weight, although it depends on the characteristic values unique to the negative electrode active material such as the specific surface area and surface functional group amount of the negative electrode active material to be used. The content is preferably 10% by weight or more and 80% by weight or less. If the concentration of the negative electrode active material is too low, the production efficiency deteriorates, the viscosity of the mixture paste tends to be low, the negative electrode active material tends to settle over time, and it may be difficult to form a uniform electrode. On the other hand, when the concentration of the negative electrode active material is too high, the viscosity of the dispersion is remarkably increased, and the dispersion efficiency and the handleability of the dispersion may be reduced.

  The addition amount of one or more dispersants selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group, It is determined by the specific surface area of the negative electrode active material to be used. In general, the dispersant is added in an amount of 0.01 parts by weight or more and 30 parts by weight or less, preferably 0.05 parts by weight or more and 25 parts by weight or less, more preferably 0.00 parts by weight or less with respect to 100 parts by weight of the negative electrode active material. Add 1 to 20 parts by weight. If the addition amount is small, a sufficient effect cannot be obtained, and even if it is added more than necessary, no significant improvement in dispersibility is observed.

  In dispersing the negative electrode active material in the solvent, 1 selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group It is preferable to add more than one type of dispersant and an acidic compound. The acidic compound to be added is at least one selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group. It is preferable to add 0.1-10 equivalent with respect to the basic functional group of a dispersing agent, and it is still more preferable to add 0.5-5 equivalent.

  As an apparatus for dispersing the negative electrode active material, for example, the following dispersers usually used for pigment dispersion or the like can be used.

  Examples of dispersers include mixers such as dispersers, homomixers, or planetary mixers; “Clearmix” manufactured by M Technique, or “Homogenizers” such as “Filmix” manufactured by PRIMIX; Paint conditioner (manufactured by Red Devil) ), Ball mill, sand mill (such as “Dynomill” manufactured by Shinmaru Enterprises Co., Ltd.), media type disperser such as attritor, pearl mill (such as “DCP mill” manufactured by Eirich), or coball mill; wet jet mill (“Genus Corporation” Medialess dispersers, such as “Genus PY”, “Starburst” manufactured by Sugino Machine, “Nanomizer” manufactured by Nanomizer, “Claire SS-5” manufactured by M Technique, or “MICROS” manufactured by Nara Machinery; And other roll mills It is, but not limited thereto. Further, as the disperser, it is preferable to use a disperser that has been subjected to a metal mixing prevention treatment from the disperser.

  For example, when using a media-type disperser, the metal agitator and vessel use a ceramic or resin disperser, or the metal agitator and the vessel surface are coated with tungsten carbide spray or resin coating. It is preferable to use a disperser that has been treated as described above. As the media, glass beads, ceramic beads such as zirconia beads or alumina beads are preferably used. Moreover, also when using a roll mill, it is preferable to use a ceramic roll. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination.

  In the case of a negative electrode active material in which particles are easily broken or crushed by a strong impact, a medialess disperser such as a roll mill or a homogenizer is preferable to a media disperser.

  Since the negative electrode mixture in the present invention is excellent in dispersibility of the negative electrode active material, the energy at the time of mixing / dispersing when preparing the negative electrode mixture paste is efficiently prevented from being disturbed by the aggregate of the negative electrode active material. It is considered that the dispersibility of the carbon material (conductive auxiliary agent) can be improved as a result of being transmitted to the carbon material (conductive auxiliary agent).

  When a negative electrode active material and a carbon material as a conductive additive are co-dispersed, various derivatives having a basic functional group used in the present invention are considered to have a dispersing effect on the carbon material as a conductive additive. It is considered that the dispersibility of the carbon material as an auxiliary agent is also improved.

  In order to improve the wettability of the negative electrode active material to the solvent and improve the dispersibility, an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, a base A negative electrode active material that has been treated in advance with one or more dispersants selected from triazine derivatives having a functional functional group can be used.

  Pre-treated with one or more dispersants selected from organic dye derivatives having basic functional groups, anthraquinone derivatives having basic functional groups, acridone derivatives having basic functional groups, and triazine derivatives having basic functional groups Examples of the method for obtaining the negative electrode active material include a method by a dry process and a method by a process in a liquid phase.

  Examples of the dry treatment include a method in which the dispersant is allowed to act (for example, adsorb) on the surface of the negative electrode active material while mixing, pulverizing, etc., the negative electrode active material and the dispersant with a dry treatment apparatus at room temperature or under heating. It is done. The equipment to be used is not particularly limited. Media type dispersers such as paint conditioner (manufactured by Red Devil), ball mill, attritor, vibration mill, kneader, roller mill, stone mill, planetary mixer, fen Medialess dispersion / kneading machines such as Shell Mixer, Hybridizer (Nara Machinery Co., Ltd.), Mechano Micros (Nara Machinery Co., Ltd.), Mechano Fusion System AMS (Hosokawa Micron Co., Ltd.) can be used. In consideration of metal contamination and the like, it is preferable to use a medialess dispersion / kneading machine.

  As the liquid phase treatment, a dispersing agent and a negative electrode active material are mixed in a solvent, and the dispersing agent acts on the negative electrode active material (for example, adsorption), and the negative electrode active material on which the dispersing agent acts is agglomerated and agglomerated. It is preferable to include a step of obtaining particles.

  In particular, a dispersant containing various derivatives having a basic functional group is completely or partially dissolved in a solvent, and the negative electrode active material is added to the solution to be mixed and dispersed. It is preferable to act on (for example, adsorb).

  As the solvent used in the step of causing the dispersant to act on the negative electrode active material (for example, adsorption), it is preferable to use a polar solvent having a relative dielectric constant of 15 or more. In particular, in order to increase the concentration of the negative electrode active material in the treatment liquid and increase the treatment efficiency, the relative dielectric constant is 15 or more and 200 or less, preferably 15 or more and 100 or less, more preferably 20 or more and 100 or less. The polar solvent is preferably used.

  In a solvent having a relative dielectric constant of less than 15, the solubility of the dispersant is remarkably lowered and the dispersibility of the negative electrode active material is lowered. Therefore, the concentration of the negative electrode active material cannot often be increased, and the relative dielectric constant is 200. In many cases, a remarkable effect cannot be obtained even if a solvent exceeding the above is used.

  As an apparatus for causing the dispersing agent to act (for example, adsorb) on the negative electrode active material while mixing and dispersing the negative electrode active material in a solvent, the above-described dispersers that are usually used for pigment dispersion and the like can be used. From the viewpoint of processing efficiency and productivity, it is preferable to use a mixer or a media-type disperser. Moreover, it is preferable to use what gave the metal mixing prevention process from an apparatus.

  Examples of the step of aggregating the negative electrode active material on which the dispersant has acted in the liquid to obtain aggregated particles include a method of heating and / or reducing the pressure of the above-mentioned treated product to distill off the solvent.

  Further, as a method of reducing the solubility or dispersibility of the dispersant on the surface of the carbon material with respect to the solvent and aggregating it, the above-mentioned treated slurry is mixed with a solvent having a relative dielectric constant of less than 15, more preferably 10 or less. The method of aggregating is mentioned. The solvent having a relative dielectric constant of less than 15 is not particularly limited. For example, methyl isobutyl ketone (relative dielectric constant: 13.1), ethyl acetate (6.0), butyl acetate (5.0), Examples include diethyl ether (4.2), xylene (2.3), toluene (2.2), heptane (1.9), hexane (1.9), pentane (1.8) and the like. These aggregates are taken out by filtration or centrifugation. The obtained processed product can be used as it is, but it is preferable to use it after washing, drying and grinding.

  When the treatment is performed in advance in an aqueous system, it is preferable to use ion-exchanged water or purified water. In order to increase the solubility of the dispersant, the pH of the treatment liquid is preferably 0.05 <pH <7, and more preferably 1 <pH ≦ 7. An acidic compound is added to make the pH of the treatment liquid acidic. Examples of the acidic compound include those described above.

  Examples of the step of aggregating the negative electrode active material on which the dispersing agent has acted in the liquid to obtain aggregated particles include a method of heating and / or reducing the pressure of the above-mentioned treated product to distill off water. In addition, examples of a method for aggregating the dispersant on the negative electrode active material surface by lowering the solubility or dispersibility in water include a method in which the pH of the treatment liquid is neutralized or basified to cause aggregation. As a basic compound to be added at this time, a metal hydroxide such as an alkali metal, a salt obtained by a reaction between a weak acid and a strong base, ammonia, an amine, etc., which is dissolved in water and shows basicity is used. be able to. Among them, it is preferable to use a base that decomposes or volatilizes in the drying process during electrode production. These aggregates are removed by filtration or centrifugation. The obtained processed product can be used as it is, but it is preferable to use it after washing, drying and grinding.

<Lithium secondary battery>
Next, a lithium secondary battery using the composition of the present invention will be described.

  The lithium secondary battery includes a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium. An electrode base layer may be formed between the positive electrode mixture layer and the current collector, or between the negative electrode mixture layer and the current collector.

  Regarding the electrode, the material and shape of the current collector to be used are not particularly limited, and as the material, metals and alloys such as aluminum, copper, nickel, titanium, and stainless steel are used. In particular, as the positive electrode material, aluminum is used as the negative electrode. The material is preferably copper. As the shape, a flat plate foil is generally used, but a roughened surface, a perforated foil shape, and a mesh shape can also be used.

The positive electrode mixture layer is composed of a positive electrode active material, a conductive additive, a binder component, and the like. The positive electrode active material is not particularly limited, and metal oxides that can be doped or intercalated with lithium ions, metal compounds such as metal sulfides, conductive polymers, and the like can be used. Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, transition metal sulfide powders such as TiS ₂ and FeS, and the like. In addition, conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene can also be used. Moreover, you may mix and use said inorganic compound and organic compound.

  As the conductive assistant, a carbon material, a metal that is difficult to alloy with lithium, a conductive polymer material, or the like can be used. Examples of binder components include ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, acrylonitrile, styrene, vinyl butyral, vinyl acetal, vinyl pyrrolidone, etc. Polymers or copolymers containing as structural units: polyurethane resins, polyester resins, phenol resins, epoxy resins, phenoxy resins, urea resins, melamine resins, alkyd resins, acrylic resins, formaldehyde resins, silicone resins, fluorine resins; carboxymethyl cellulose Cellulose resins such as: rubbers such as styrene-butadiene rubber and fluororubber; conductive resins such as polyaniline and polyacetylene. Moreover, the modified body and mixture of these resin, and a copolymer may be sufficient. In particular, it is preferable to use a polymer compound containing a fluorine atom in the molecule, for example, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene, etc. from the viewpoint of resistance.

  The electrode mixture layer is formed on the current collector by directly applying the electrode mixture paste described above on the current collector and drying the electrode mixture layer, and after forming the electrode base layer on the current collector. The method of apply | coating material paste and drying is mentioned. In addition, when the electrode mixture layer is formed on the electrode foundation layer, after applying the electrode foundation paste on the current collector, the electrode mixture paste may be applied in a wet state and then dried. good. The thickness of the electrode mixture layer is generally 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less.

  There is no restriction | limiting in particular about the coating method, A well-known method can be used. Specific examples include a die coating method, a dip coating method, a roll coating method, a doctor coating method, a spray coating method, a gravure coating method, a screen printing method, and an electrostatic coating method. Moreover, you may perform the rolling process by a lithographic press, a calender roll, etc. after application | coating.

As the electrolytic solution constituting the lithium secondary battery of the present invention, an electrolyte containing lithium is dissolved in a non-aqueous solvent. As the electrolyte, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₃ C , LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, LiBPh _{4 and the} like, but are not limited thereto.

  The non-aqueous solvent is not particularly limited, but carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate, γ-butyrolactone, γ-valerolactone, and γ-octanoic lactone. Lactones such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, 1,2-dibutoxyethane, etc. Glymes, esters such as methyl formate, methyl acetate and methyl propionate, sulfoxides such as dimethyl sulfoxide and sulfolane, and nitriles such as acetonitrile. These solvents may be used alone or in combination of two or more.

  Furthermore, the electrolyte solution may be a gelled polymer electrolyte held in a polymer matrix. Examples of the polymer matrix include, but are not limited to, an acrylate resin having a polyalkylene oxide segment, a polyphosphazene resin having a polyalkylene oxide segment, a polysiloxane having a polyalkylene oxide segment, and the like.

  The structure of the lithium secondary battery using the composition of the present invention is not particularly limited, but it is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary. Paper type, cylindrical type, button type, laminated Various shapes can be formed according to the purpose of use, such as a mold.

[Example]
EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to an Example. In the examples, “parts” represents “parts by weight” and “%” represents “% by weight”.

  Tables 1 to 4 show the structures of the dispersants used in the examples.

<Preparation of negative electrode active material dispersion>
[Negative electrode active material dispersions 1 to 27]
In accordance with the composition shown in Table 5, a solvent and various derivatives having a basic functional group were charged into a container, mixed and stirred to completely or partially dissolve the derivative. Next, the negative electrode active material was added and dispersed with a media mix disperser, FILMMIX (manufactured by PRIMIX), to obtain negative electrode active material dispersions (1) to (27).

As the negative electrode active material, mesophase carbon MFC (mesophase carbon) (MCMB 6-28, average particle size 5 to 7 μm, specific surface area 4 m ² / g manufactured by Osaka Gas Chemical Co., Ltd.), spherical graphite (average particle size about 10 to 20 μm, Manufactured by Nippon Graphite Co., Ltd.), lithium titanate (Li ₄ Ti ₅ O ₁₂ , average primary particle size 0.3 μm, specific surface area 15 m ² / g), lithium vanadium oxide (Li _1.1 V _0.9 O ₂₎ One prepared by the method described in Kai 2008-153177) was used.

  Moreover, about the composite negative electrode active material, the composite negative electrode active material (a)-(d) adjusted with the method mentioned later was used.

  About the negative electrode active material previously processed with the various derivatives which have a basic functional group, the dispersing agent pretreatment negative electrode active material (e) adjusted by the method mentioned later was used.

  In Table 5, the nonionic surfactant is Emulgen A-60 (polyoxyethylene derivative, manufactured by Kao Corporation), and the anionic surfactant is demole N (β-naphthalenesulfonic acid-formalin condensate). Sodium salt, manufactured by Kao Corporation).

<Preparation of composite negative electrode active material>
[Adjustment of composite negative electrode active material (a)]
47 parts of mesophase carbon (MCMB 6-28, average particle size 5-7 μm, specific surface area 4 m ² / g made by Osaka Gas Chemical Co.), acetylene black (Denka Black HS-100, primary particle size 48 nm, ratio) 3 parts of a surface area of 48 m ² / g, manufactured by Denki Kagaku Kogyo Co., Ltd. were treated with hybridization (manufactured by Nara Koki Seisakusho Co., Ltd.) to obtain a composite negative electrode active material (a).
[Adjustment of composite negative electrode active material (b)]
47 parts of lithium titanate (Li ₄ Ti ₅ O ₁₂ , average primary particle size 0.3 μm, specific surface area 15 m ² / g), acetylene black (Denka Black HS-100, primary particle size 48 nm, specific surface area 48 m ² / g, 3 parts (manufactured by Denki Kagaku Kogyo Co., Ltd.) were treated with hybridization (manufactured by Nara Opportunity Manufacturing Co., Ltd.) to obtain a composite negative electrode active material (b).
[Adjustment of composite negative electrode active material (c)]
Lithium vanadium oxide (Li _1.1 V _0.9 O ₂ , prepared by the method described in JP-A-2008-153177), acetylene black (DENKA BLACK HS-100, primary particle size 48 nm, specific surface area 48 m ² / g 3 parts, manufactured by Denki Kagaku Kogyo Co., Ltd.) were treated with hybridization (manufactured by Nara Opportunity Manufacturing Co., Ltd.) to obtain a composite negative electrode active material (c).
[Adjustment of composite negative electrode active material (d)]
Silicon powder (average primary particle diameter: 3 μm) was subjected to CVD treatment using toluene as a carbon source to obtain a carbon-coated composite negative electrode active material (d).

<Preparation of dispersant pretreated negative electrode active material>
[Preparation of dispersant pretreated negative electrode active material (e)]
Dispersant J5 parts was added to 2000 parts of ion-exchanged water. Acetic acid was added while stirring and mixing with a disper to adjust the pH of the solution to about 4, and the dispersant was dissolved. Then, 100 parts of mesophase carbon MFC (mesophase carbon) (MCMB 6-28, average particle size 5-7 μm, specific surface area 4 m ² / g manufactured by Osaka Gas Chemical Co., Ltd.) was added, and the pH was 3.5-4.5. The mixture was stirred and mixed while maintaining the range. Next, after passing the treated slurry through a strainer with a magnet, aqueous ammonia was added to adjust the pH of the solution to 8-9. At this time, since the viscosity of the liquid rapidly increased, ion-exchanged water was appropriately added. The aggregate was collected by filtration, washed with ion-exchanged water, then dried and pulverized to obtain a dispersant pretreated negative electrode active material (e).

<Co-dispersion adjustment of negative electrode active material and conductive additive>
According to the composition shown in Table 6, a container was charged with various derivatives having a solvent and a basic functional group, mixed and stirred to completely or partially dissolve the derivative. Next, a negative electrode active material and a conductive additive were added and dispersed with a media mix disperser Fillmix (manufactured by Primex) to obtain negative electrode active material conductive aid co-dispersions (28) to (31).

The following were used as conductive assistants.
-Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.):
Acetylene black, primary particle size 48 nm, specific surface area 48 m ² / g.
・ Denka Black FX-35 (manufactured by Denki Kagaku Kogyo Co., Ltd.):
Acetylene black, primary particle size 23 nm, specific surface area 133 m ² / g.
Super-P Li (manufactured by TIMCAL):
Furnace black, primary particle size 40 nm, specific surface area 62 m ² / g.

<Evaluation of wettability of dispersed negative electrode active material>
For the negative electrode active material dispersions 1, 2, 7, 9, 21, 22, and 23, the wettability evaluation of the negative electrode active material after the dispersion treatment was performed.

After the solvent of each negative electrode active material dispersion was distilled off under reduced pressure using an evaporator, the obtained residue was dried under reduced pressure at 80 ° C. for 10 hours. Subsequently, the dried product was pulverized with an agate mortar and further dried under reduced pressure at 80 ° C. for 12 hours. The obtained dried product was pulverized again in an agate mortar, and then applied with a load of 500 kgf / cm ² in a tablet molding machine (Specac) to produce a negative electrode active material pellet (diameter 10 mm, thickness 0.5 mm). did. A droplet in which ethylene carbonate and diethyl carbonate were mixed 1: 1 was dropped on this pellet with a microsyringe, and the time for the droplet to penetrate the pellet was measured. This measurement was performed 5 times for each sample, and those whose average permeation time was less than 1 second was “◎”, those that were 1 second or more and less than 5 seconds were “◯”, 5 seconds or more and 10 seconds. Those that were less than “Δ” were those that were 10 seconds or longer, and “x”.

The results are shown in Table 7. The negative electrode active material dispersed using various derivatives having a basic functional group according to the present invention has improved wettability with respect to an electrolytic solution as compared with those of Comparative Examples 1 and 2.

<Preparation of negative electrode mixture paste for lithium secondary battery>
Using negative electrode active material dispersions (1) to (27) and negative electrode active material conductive additive co-dispersions (28) to (31), negative electrode mixture pastes (1) to (31) were prepared as follows. did. The compositions are shown in Table 8 and Table 9.
[Negative electrode paste (1), (4), (7), (8), (10), (15), (16), (19),
(27)]
Add 146.5 parts of negative electrode active material dispersion, 4.9 parts of polyvinylidene fluoride (KF polymer W1100, manufactured by Kureha Co., Ltd.), 2 parts of conductive additive and 18 parts of N-methyl-2-pyrrolidone as a binder. To obtain a negative electrode mixture paste.

  In addition, about the negative electrode active material dispersion which uses the composite negative electrode active material, the amount of conductive support agents was 1 part.

[Negative electrode paste (2), (3), (5), (6), (9), (11) to (14), (17), (18), (20) to (26)]
146.5 parts of negative electrode active material dispersion, 1 part of carboxymethyl cellulose (Sunrose F300MC, manufactured by Nippon Paper Chemicals Co., Ltd.) as a binder, 4 parts of styrene butadiene rubber (TRD2001, manufactured by JSR), 2 parts of conductive additive and purification 18 parts of water was kneaded with a planetary mixer to obtain a negative electrode mixture paste.
In addition, about the negative electrode active material dispersion which uses the composite negative electrode active material, the amount of conductive support agents was 1 part.

[Negative electrode paste (28), (30)]
148.5 parts of negative electrode active material conductive additive co-dispersion, 1 part of carboxymethyl cellulose (Sunrose F300MC, manufactured by Nippon Paper Chemicals) as a binder, 4 parts of styrene butadiene rubber (TRD2001, manufactured by JSR), 18 parts of purified water Was kneaded with a planetary mixer to obtain a negative electrode mixture paste.
[Negative electrode paste (29), (31)]
Add 148.5 parts of negative electrode active material conductive auxiliary co-dispersion, 4.9 parts of polyvinylidene fluoride (KF polymer W1100, manufactured by Kureha) as a binder, and 18 parts of N-methyl-2-pyrrolidone, and use a planetary mixer. The mixture was kneaded to obtain a negative electrode mixture paste.

表８中、略称は以下に示す通りである。
ＰＶＤＦ：ポリフッ化ビニリデン
ＳＢＲ：スチレンブタジエンゴム、ＣＭＣ：カルボキシメチルセルロース

In Table 8, abbreviations are as shown below.
PVDF: Polyvinylidene fluoride SBR: Styrene butadiene rubber, CMC: Carboxymethyl cellulose

In Table 9, abbreviations are as shown below.
PVDF: Polyvinylidene fluoride SBR: Styrene butadiene rubber, CMC: Carboxymethyl cellulose

<Preparation of negative electrode for lithium secondary battery>
The various negative electrode mixture pastes prepared above were applied onto a copper foil having a thickness of 20 μm to be a current collector using a doctor blade, followed by drying under reduced pressure, rolling, and a negative electrode mixture layer having a thickness of 100 μm ( 1) to (31) were produced.
<Assembly of lithium secondary battery negative electrode evaluation cell>
A separator made of a porous polypropylene film between the working electrode and the counter electrode (# 2400, manufactured by Celgard Co., Ltd.) with the negative electrode prepared previously punched to a diameter of 9 mm and used as a working electrode, and a metallic lithium foil (thickness 0.15 mm) as a counter electrode Is inserted and laminated, filled with an electrolyte (nonaqueous electrolyte in which LiPF ₆ is dissolved at a concentration of 1M in a mixed solvent of ethylene carbonate and diethyl carbonate in a ratio of 1: 1), and a bipolar metal cell (Hosen) (HS flat cell). The cell was assembled in a glove box substituted with argon gas, and after the cell was assembled, the following battery characteristics were evaluated.

<Characteristic evaluation of lithium secondary battery negative electrode>
[Charge / Discharge Cycle Characteristics Example 6-30, Comparative Example 3-8]
The battery evaluation cell thus prepared was fully charged at 0.05 V by constant current and constant voltage charging at room temperature (25 ° C.), charging rate of 0.2 C and 1.0 C, and the voltage was constant at the same rate as charging. Charging / discharging for discharging until 1.5V was taken as one cycle (charging / discharging interval rest time 30 minutes).
First, this charge / discharge operation was performed five times, and the discharge capacity at the sixth time was set as an initial value. Then, this cycle was performed 20 times in total, and charge / discharge cycle characteristic evaluation (evaluation apparatus: SM-8 manufactured by Hokuto Denko) was performed. Moreover, the cell after evaluation was decomposed | disassembled, the presence or absence of the electrode coating film defect was confirmed visually, and the thing without a problem was set as "(circle)". The evaluation results are shown in Table 10 and Table 11.

表１０および表１１の結果から分かる通り、実施例６〜３０は、本発明で添加する分散剤を使用していない比較例３〜８と比べて、負極活物質の分散性が優れていて粗大な凝集粒子が存在しないため、２０サイクル容量維持率が向上した。

As can be seen from the results of Table 10 and Table 11, Examples 6 to 30 are excellent in dispersibility of the negative electrode active material and coarse compared with Comparative Examples 3 to 8 in which the dispersant added in the present invention is not used. Since no agglomerated particles were present, the 20 cycle capacity retention rate was improved.

[Negative Electrode Active Material Dispersion Storage Test Examples 31, 32, Comparative Examples 9, 10]
About negative electrode compound paste (1), (2), (22), (23), after preserve | saving for 1 week at 40 degreeC, the negative electrode and the cell for evaluation were created by the method mentioned above, Examples 6-30 and comparison The charge / discharge cycle test was conducted in the same manner as in Examples 3-8. The results are shown in Table 12.

As can be seen from the results in Table 12, since Examples 31 and 32 have excellent dispersion stability of the negative electrode active material, the negative electrode mixture paste is added in the present invention when evaluated after being stored at 40 ° C. for one week. Compared to Comparative Examples 9 and 10 in which no dispersant was used, the 20-cycle capacity retention rate was high.

Claims (2)

One or more dispersants selected from an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, and a triazine derivative having a basic functional group; Alternatively, a negative electrode composite material for a lithium ion secondary battery, comprising at least one negative electrode active material selected from Group B.
(Group A: Mesophase carbon, spheroidal graphite, lithium titanate and lithium vanadium oxide Group B: Carbon which is at least one selected from the group consisting of mesophase carbon, lithium titanate, lithium vanadium oxide and silicon powder is a conductive substance Negative electrode active material combined with materials) A lithium secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein the negative electrode mixture layer is ,
A lithium secondary battery produced by using the negative electrode mixture according to claim 1.