JP2015176688A - Composition for secondary battery, and secondary battery electrode and secondary battery using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a secondary battery electrode including a conductive assistant, which is excellent in dispersibility and dispersion stability of the conductive assistant and dispersion stability of mixture slurry, and also to provide an electrode and a secondary battery which have excellent discharge capacity by using the composition.SOLUTION: The problems are solved by a composition for a secondary battery including a polymer dispersant (A) having a repeating unit represented by general formula (1) and a carbon material (C), and a secondary battery electrode and a secondary battery which are formed by using the composition for the secondary battery.

Description

  The present invention relates to a battery composition used for producing an electrode constituting a secondary battery, a secondary battery electrode and a 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 ion secondary batteries are being actively developed. As an electrode of a lithium ion 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 a lithium ion A negative electrode is used in which an electrode mixture made of a removable negative electrode active material, a conductive additive, an organic binder, and the like is fixed to the surface of a current collector of a metal foil.

  In general, lithium transition metal composite oxides such as lithium cobaltate and lithium manganate are used as the positive electrode active material, but these have low electronic conductivity and have sufficient battery performance when used alone. I can't get it. Therefore, attempts have been made to improve the conductivity and reduce the internal resistance of the electrode by adding a carbon material such as carbon black (for example, acetylene black) or graphite (graphite) as a conductive aid.

In this way, reducing the internal resistance of the electrode is one of the very important factors in enabling discharge with a large current and improving the efficiency of charge and discharge.
However, carbon materials with excellent electrical conductivity (conducting aids) have high cohesion due to their large structure and specific surface area, making it difficult to uniformly mix and disperse in the electrode mixture forming slurry of a lithium ion secondary battery. It is. And, when the dispersibility and particle size control of the carbon material that is the conductive auxiliary agent are insufficient, the internal resistance of the electrode cannot be reduced because the uniform conductive network is not formed, and as a result, the lithium that is the active material There has been a problem that the performance of transition metal composite oxides and graphite cannot be sufficiently extracted. In addition, if the dispersion of the conductive additive in the electrode mixture is insufficient, resistance distribution occurs on the electrode plate due to partial aggregation, current concentrates when used as a battery, and partial heat generation occurs. In addition, problems such as accelerated deterioration may occur.

  In addition, when an electrode mixture layer is formed on an electrode current collector such as a metal foil, repeated charging and discharging a large number of times causes the interface between the current collector and the electrode mixture layer, and the active material and the conductive material inside the electrode mixture. There is a problem in that the adhesion at the auxiliary agent interface is deteriorated and the battery performance is lowered. This is because the active material and the electrode mixture layer are repeatedly expanded and contracted by doping and dedoping of lithium ions during charge and discharge, so that the electrode mixture layer and the current collector interface and the active material and the conductive auxiliary agent interface are localized. This is thought to be due to the generation of shear stress and the deterioration of interfacial adhesion. In this case as well, if the dispersion of the conductive additive is insufficient, the adhesion reduction becomes significant. This is considered to be because when coarse agglomerated particles are present, the stress is hardly relaxed.

  In addition, as a problem between the electrode current collector and the electrode mixture, for example, when aluminum is used as the positive electrode current collector, an insulating oxide film is formed on this surface, and the contact between the electrode current collector and the electrode mixture There is also a problem that resistance increases.

  Several proposals have been made for the problems between the electrode current collector and the electrode mixture as described above. For example, Patent Document 1 and Patent Document 2 attempt a method of forming a coating film in which a conductive agent such as carbon black is dispersed on the collector electrode as an electrode underlayer. If it is bad, sufficient effect cannot be obtained.

  In a lithium ion secondary battery, the dispersion of a carbon material that is a conductive aid is one of the important points. Patent Documents 3 and 4 describe examples in which a surfactant is used as a dispersant when carbon black is dispersed in a solvent. However, since the surfactant has a weak adsorption force on the surface of the carbon material, it is necessary to increase the amount of the surfactant added in order to obtain good dispersion stability. As a result, the amount of the active material that can be contained Decreases and the battery capacity decreases. Further, if the surfactant is not sufficiently adsorbed on the carbon material, the carbon material will aggregate. Further, a general surfactant has a remarkably low dispersion effect in an organic solvent as compared with dispersion in an aqueous solution.

  Further, in Patent Document 5 and Patent Document 6, when carbon black is dispersed in a solvent, the dispersion state of the carbon slurry is improved by adding a dispersion resin, and the carbon slurry and the active material are mixed. A method for producing an electrode mixture is disclosed. However, although this method improves the dispersibility of carbon black, a large amount of dispersed resin is required to disperse fine carbon black having a large specific surface area, and a dispersed resin having a large molecular weight is carbon black. Since the surface is covered, the conductive network is obstructed and the resistance of the electrode is increased. As a result, the effect of improving the dispersion of carbon black may be offset.

  In addition to the improvement in the dispersibility of the electrode material, an important factor for improving the charge / discharge efficiency is an improvement in the wettability of the electrode with respect to the electrolytic solution. Since the electrode reaction occurs at the contact interface between the electrode material surface and the electrolytic solution, it is important that the electrolytic solution penetrates into the electrode and the electrode material is well wetted. As a method of promoting the electrode reaction, a method of increasing the surface area of the electrode by using a fine active material or a conductive auxiliary agent has been studied. There is a problem that it is difficult to improve battery performance because the contact area of the battery does not increase.

  As a method for improving the wettability of an electrode, Patent Document 7 discloses a method of providing fine voids between active material particles by including carbon fibers having a fiber diameter of 1 to 1000 nm in an electrode. . However, since carbon fibers are usually intertwined in a complicated manner, uniform dispersion is difficult, and a uniform electrode cannot be produced simply by mixing carbon fibers. In addition, in this document, there is a method of using carbon fiber whose surface is oxidized for dispersion control. However, when carbon fiber is directly oxidized, the conductivity and strength of carbon fiber are reduced. There is a problem of end up. Patent Document 8 discloses a method for improving the wettability by adsorbing a surfactant such as a higher fatty acid alkali salt to a negative electrode material mainly composed of carbon powder. In particular, the agent often does not have sufficient dispersion performance in a non-aqueous system, and a uniform electrode coating film cannot be obtained. In these examples, the total performance including the dispersibility of the electrode material was insufficient.

JP 2000-123823 A Japanese Patent Laid-Open No. 2002-298753 JP-A-63-236258 JP-A-8-190912 Japanese Patent Laid-Open No. 2003-157846 JP-T-2006-51679 gazette Japanese Patent Laying-Open No. 2005-063955 JP-A-6-60877

  In view of the problems as described above, the problem to be solved by the present invention is to disperse the dispersion of the conductive additive, the dispersion stability, and the dispersion stability of the mixture slurry in the secondary battery forming composition containing the conductive assistant. It is in providing the composition for secondary battery electrode formation excellent in the. Moreover, it is providing the electrode and secondary battery which were excellent in discharge capacity by using this.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have shown, as a polymer dispersant (A), a general formula (1) when dispersing a carbon material as a conductive additive. By using a polymer containing a structure, it is excellent in the dispersibility and dispersion stability of the conductive additive and the dispersion stability of the composite slurry, and is effective for improving the performance of the secondary battery. It has been found that a composition (dispersion and mixture slurry) can be obtained, and has led to the present invention.

  That is, the present invention relates to a secondary battery composition comprising a polymer dispersant (A) having a repeating unit represented by the following general formula (1) and a carbon material (C).

［一般式（１）中、
Ａ¹は、２価の連結基（トリアジン環を含むものを除く）または単結合を表す。
Ｄ¹は、一般式（２）に示す構造を表す。
Ｒ¹は、アルキル基または水素原子を表す。] General formula (1)

[In general formula (1),
A ¹ represents a divalent linking group (excluding those containing a triazine ring) or a single bond.
D ¹ represents the structure represented by the general formula (2).
R ¹ represents an alkyl group or a hydrogen atom. ]

［一般式（２）中、
Ｅ¹、Ｅ²、Ｅ³、およびＥ⁴は、それぞれ独立に、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアリール基、置換基を有していてもよいヘテロアリール基、置換基を有していてもよいオキシアルキル基、または水素原子を表し、Ｅ¹、Ｅ²、Ｅ³、およびＥ⁴のうちいずれか一つは、Ａ¹との結合手である。
Ｇ¹およびＧ²は、それぞれ独立に、−Ｎ（Ｒ³）−、−Ｏ−、または、−ＣＨ₂−を表し、Ｒ³は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアリール基、置換基を有していてもよいヘテロアリール基、置換基を有していてもよいオキシアルキル基、または水素原子を表す。
Ｇ³は、−Ｃ（＝Ｏ）−、−Ｃ（＝Ｓ）−、または、−ＣＨ（ＯＣＨ₃）−を表す。］ General formula (2)

[In general formula (2),
E ¹ , E ² , E ³ , and E ⁴ each independently have an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. Represents a good aryl group, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or a hydrogen atom, and among E ¹ , E ² , E ³ and E ⁴ One of them is a bond with A ¹ .
G ¹ and G ² each independently represent —N (R ³ ) —, —O—, or —CH ₂ —, and R ³ represents an alkyl group or substituent which may have a substituent. An alkenyl group which may have a substituent, an aryl group which may have a substituent, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or hydrogen Represents an atom.
G ³ represents —C (═O) —, —C (═S) —, or —CH (OCH ₃ ) —. ]

  In addition, the present invention relates to the composition for a secondary battery, wherein the polymer dispersant (A) has a repeating unit having a hydroxyl group.

  In addition, the present invention relates to the composition for a secondary battery, wherein the repeating unit having a hydroxyl group is represented by the following general formula (3).

[一般式（３）中、Ａ²は２価の連結基または単結合を示す。Ｒ²は置換基を有していてもよいアルキル基または水素原子を表す。] General formula (3)

[In General Formula (3), A ² represents a divalent linking group or a single bond. R ² represents an alkyl group which may have a substituent or a hydrogen atom. ]

  In addition, the present invention relates to the composition for a secondary battery, wherein the polymer dispersant (A) has a weight average molecular weight of 15,000 or more and 100,000 or less.

  Further, the present invention further includes at least one derivative (D) selected from the group consisting of an organic dye derivative having an acidic functional group and a triazine derivative having an acidic functional group. The present invention relates to a composition for use.

  The present invention further relates to the composition for a secondary battery, further comprising a solvent (E) and a binder resin (F).

  The present invention further relates to the composition for a secondary battery, further comprising at least one active material (G) selected from the group consisting of a positive electrode active material and a negative electrode active material.

  The present invention also relates to the composition for a secondary battery, wherein the ratio of the average particle diameter of the active material (G) / the dispersed particle diameter (D50) of the carbon material is 2 or more and 100 or less.

  The present invention also provides a secondary battery electrode having a composite material layer on a current collector, wherein the composite material layer is formed of the secondary battery composition. It relates to an electrode.

  Furthermore, the present invention is a 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, wherein the positive electrode mixture The present invention relates to a secondary battery, wherein a layer or a negative electrode mixture layer is formed of the composition for secondary batteries.

  According to a preferred embodiment of the present invention, it is possible to provide a composition for forming a secondary battery electrode that is excellent in dispersibility of an active material and a conductive additive. Moreover, the electrode and the secondary battery using the electrode forming composition of the present invention can improve charge / discharge cycle characteristics. This is not only because the dispersion and mixture slurry of carbon material particles having excellent dispersibility and dispersion stability can be prepared by using the dispersant, but also by using the polymer dispersant (A). It is thought that this sometimes causes a uniform and strong interaction between the active material (G) and the carbon material (C). Therefore, the secondary battery composition of the present invention can be used for lithium ion secondary batteries, alkaline secondary batteries, nickel cadmium secondary batteries, alkaline manganese batteries, lead batteries, fuel cells, capacitors, etc. It is suitable for use in a lithium ion secondary battery.

<Polymer dispersant (A)>
The polymer dispersant (A) has excellent dispersibility with respect to the carbon material (C) as a conductive auxiliary agent by having the repeating unit represented by the general formula (1), and the conductive auxiliary agent has a conductive property. Dispersion stability can be achieved without impairing properties. The polymer dispersant (A) only needs to contain the constituent units represented by the general formula (1) within a limited range, and the arrangement of the constituent units may be random or block.

［一般式（１）中、
Ａ¹は、２価の連結基（トリアジン環を含むものを除く）または単結合を表す。
Ｄ¹は、一般式（２）に示す構造を表す。
Ｒ¹は、アルキル基または水素原子を表す。] General formula (1)

[In general formula (1),
A ¹ represents a divalent linking group (excluding those containing a triazine ring) or a single bond.
D ¹ represents the structure represented by the general formula (2).
R ¹ represents an alkyl group or a hydrogen atom. ]

［一般式（２）中、
Ｅ¹、Ｅ²、Ｅ³、およびＥ⁴は、それぞれ独立に、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアリール基、置換基を有していてもよいヘテロアリール基、置換基を有していてもよいオキシアルキル基、または水素原子を表し、Ｅ¹、Ｅ²、Ｅ³、およびＥ⁴のうちいずれか一つは、Ａ¹と結合手である。
Ｇ¹およびＧ²は、、それぞれ独立に、−Ｎ（Ｒ³）−、−Ｏ−、または、−ＣＨ₂−を表し、Ｒ³は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアリール基、置換基を有していてもよいヘテロアリール基、置換基を有していてもよいオキシアルキル基、または水素原子を表す。
Ｇ³は、−Ｃ（＝Ｏ）−、−Ｃ（＝Ｓ）−、または、−ＣＨ（ＯＣＨ₃）−を表す。］ General formula (2)

[In general formula (2),
E ¹ , E ² , E ³ , and E ⁴ each independently have an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. Represents a good aryl group, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or a hydrogen atom, and among E ¹ , E ² , E ³ and E ⁴ One of them is A ¹ and a bond.
G ¹ and G ² each independently represent —N (R ³ ) —, —O—, or —CH ₂ —, wherein R ³ represents an alkyl group which may have a substituent, An alkenyl group which may have a group, an aryl group which may have a substituent, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or Represents a hydrogen atom.
G ³ represents —C (═O) —, —C (═S) —, or —CH (OCH ₃ ) —. ]

Examples of functional groups are given below, but the functional groups are not limited thereto. These functional groups may have a substituent, and examples of the substituent include the following substituent group.
(Alkyl group)
The alkyl group of the present application may be linear, branched or cyclic. The total number of carbon atoms in the alkyl group is preferably 1-30, and more preferably 1-16. Specifically, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-octyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n- Hexadecyl group, n-octadecyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3-sulfopropyl group, 4-sulfobutyl group, cyclohexyl group and the like can be mentioned.
(Alkenyl group)
As the alkenyl group of the present application, a linear or branched alkenyl group (vinyl, allyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 1-methyl -2-propenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 2-methacryloyloxyethyl, 2-acryloyloxyethyl, and 2-acryloyloxypropyl groups), and cycloalkenyl groups ( 2-cyclohexenyl, 3-cyclohexenyl and the like).
(Aryl group)
As an aryl group of this application, it is preferable that the total carbon number of an aryl group is 6-30, and it is still more preferable that it is 6-16. For example, phenyl group, 4-tolyl group, 4-methoxyphenyl group, 2-chlorophenyl group, 3- (3-sulfopropylamino) phenyl group, benzyl group, o-xylyl group, tosyl group, 4-sulfamoyl group, 4 -Ethoxyethylsulfamoyl, 3-dimethylcarbamoyl group, etc. are mentioned.
(Heteroaryl group)
The heteroaryl group of the present application has a structure in which a monovalent heterocyclic group is substituted for the above-described aryl group. The monovalent heterocyclic group that can be substituted with an aryl group may be saturated or unsaturated, and includes the following aromatic heterocyclic groups, such as a nitrogen atom, a sulfur atom, and an oxygen atom in the ring. What contains any of a hetero atom is mentioned, It is preferable that it is a C1-C30 heterocyclic group, and it is still more preferable that it is a 1-15 heterocyclic group. Specifically, for example, 2-pyridyl group, glycyl group, pyranyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2-benzoxazolyl group, 2-furyl group, tetrahydrofurfuryl group Etc.
(Oxyalkyl group)
As an oxyalkyl group of this application, it is preferable that it is a C1-C20 oxyalkyl group, and it is still more preferable that it is a 1-5 oxyalkyl group. Specific examples include a methoxy group, an ethoxy group, a propoxy group, an isooxy group, a butoxy group, an isobutoxy group, and a tert-butoxy group.

(Substituent group)
Specific examples of the substituent in the case where the functional group may have a substituent include a halogen atom, an aliphatic group, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, and an aliphatic group. Oxycarbonyl group, aryloxycarbonyl group, acyl group, hydroxy group, aliphatic oxy group, aryloxy group, acyloxy group, carbamoyloxy group, heterocyclic oxy group, amino group, aliphatic amino group, arylamino group, heterocyclic ring Amino group, acylamino group, carbamoylamino group, sulfamoylamino group, aliphatic oxycarbonylamino group, aryloxycarbonylamino group, aliphatic sulfonylamino group, arylsulfonylamino group, nitro group, aliphatic thio group, arylthio group , Aliphatic sulfonyl group, arylsulfonyl group, sulfamoy Group, a sulfo group, an imide group, or a heterocyclic thio group and the like Ageraru.

R ¹ in the general formula (1) represents an alkyl group or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably a methyl group or a hydrogen atom, It is particularly preferred.

E ¹ , E ² , E ³ and E ⁴ in the general formula (2) are preferably an unsubstituted oxyalkyl group or a hydrogen atom, and particularly preferably a hydrogen atom. Further, E ² or E ³ is preferable as a bond with A ¹ .

Examples of G ¹ and G ² in the general formula (2) include —O—, —CH ₂ —, or —N (R ³ ) —, preferably —N (R ³ ) —.

R ³ in the general formula (2) is preferably an alkyl group which may have a substituent, an oxyalkyl group which may have a substituent, or a hydrogen atom, more preferably unsubstituted. An alkyl group, an unsubstituted oxyalkyl group, or a hydrogen atom, more preferably an unsubstituted alkyl group having 1 to 6 carbon atoms, an unsubstituted oxyalkyl group, or a hydrogen atom, particularly preferably. It is a hydrogen atom.

G ³ in the general formula (2) is preferably —C (═O) —.

In general formula (1), examples of the divalent linking group for A ¹ (excluding those containing a triazine ring) include linking groups represented by the following general formula (4).

General formula (4)

In general formula (4),
H ¹ is a divalent linking group or a single bond containing any of oxygen, sulfur, nitrogen, and silicon;
J ¹ is an alkylene group which may have a substituent, an arylene group which may have a substituent, or a single bond;
H ² is a divalent linking group or a single bond containing any of oxygen, sulfur, nitrogen, and silicon,
J ² is a linking group represented by the following general formula (5) or a single bond,
H ³ is a divalent linking group or a single bond containing any of oxygen, sulfur, nitrogen, and silicon.

Examples of the divalent linking group containing any of oxygen, sulfur, nitrogen, and silicon in H ¹ of the general formula (4) include an amide group, a urea group, a urethane group, an ester group, an ether group, a carbonyl group, and a silyl ether group. , Sulfoamide group, sulfonic acid ester group, sulfonyl group, sulfinyl group, thioether group, heterylene group (preferably having a C number of 1 to 26, such as 6-chloro-1,3,5-triazyl-2,4-diyl group, pyrimidine -2,4-diyl group, quinoxaline-2,3-diyl group), sulfide group, imino group, and dimethylsilyl group. Preferred are amide group, urea group, urethane group, ester group, ether group, carbonyl group, and sulfoamide group, and more preferred are amide group, urea group, urethane group, ester group, ether group, and carbonyl group. is there.

As the alkylene group which may have a substituent in J ¹ of the general formula (4), a linear alkylene group (such as trimethylene, tetramethylene, pentamethylene, hexamethylene, dodecamethylene group), a branched alkylene group (2 , 4,4'-trimethylhexamethylene group, etc.), cyclic alkylene group (1,2-cyclopentyl group, 1,3-cyclopentyl group, 1,2-cyclohexyl group, 1,3-cyclohexyl group, 1,4-cyclohexyl group) Group, methyl-2,4-cyclohexyl group, and methyl-2,6-cyclohexyl group), preferably an unsubstituted alkylene group, an unsubstituted arylene group, or a single bond, Preferred is an unsubstituted alkylene group having 1 to 18 carbon atoms, an unsubstituted arylene group, or a single bond, and particularly preferred. Ku is an unsubstituted alkylene group having 1 to 18 carbon atoms, or a single bond.

As the arylene group which may have a substituent in J ¹ of the general formula (4), a phenylene group (1,3-phenylene, 1,4-phenylene group, 2-methyl-1,3-phenylene group, 4-methyl-1,3-phenylene, 1,3-dimethylphenylene, 1,4-dimethylphenylene group, and 1,4-diethylphenylene group), naphthylene group (1,2-naphthylene, 1,3-naphthylene, 1,4-naphthylene, 1,5-naphthylene, 1,6-naphthylene, 1,7-naphthylene, 1,8-naphthylene, 2,3-naphthylene, and 2,6-naphthylene).
An unsubstituted arylene group is preferable, and an unsubstituted arylene group having 6 to 10 carbon atoms is more preferable.

Examples of the divalent linking group containing any of oxygen, sulfur, nitrogen and silicon in H ² and H ³ of the general formula (4) include any of oxygen, sulfur, nitrogen and silicon in H ¹ of the general formula (4) It is synonymous with the bivalent coupling group or single bond containing these.

J ² in the general formula (4) is a linking group or a single bond shown in the general formula (5).

General formula (5)

In the general formula (5), R ¹⁵ is preferably an alkylene group which may have a substituent, an arylene group which may have a substituent, or a single bond,
J ³ is —CH ₂ —NH—CO—O—, —CH ₂ —, or a single bond,
R ¹⁶ represents an alkylene group which may have a substituent, an arylene group which may have a substituent, or a single bond.

J ^{3 in the} general formula (5) is preferably —CH ₂ —.

The alkylene group which may have a substituent in R ¹⁵ and R ¹⁶ of the general formula (5), and the arylene group which may have a substituent include a substituent in J ¹ of the general formula (4). It is synonymous with the arylene group which may have the alkylene group and substituent which may have.

When the group represented by R ¹⁵ or R ¹⁶ in the general formula (5) has a substituent, it is preferably an unsubstituted alkyl group, more preferably a methyl group.

R ¹⁵ or R ¹⁶ in the general formula (5) is preferably a cyclic alkylene group which may have a substituent or an arylene group which may have a substituent, more preferably a methyl group. A cyclic alkylene group which may have, or an unsubstituted arylene group, particularly preferably a 1,3-cyclohexyl group having a methyl group, or an unsubstituted naphthylene group.

  The average molecular weight of the polymer dispersant (A) is preferably from 1,000 to 200,000, more preferably from 15,000 to 200,000.

[Repeating unit containing a hydroxyl group]
The polymer dispersant (A) preferably further has a repeating unit containing a hydroxyl group, and the structure of the following general formula (3) is preferred as the repeating unit containing a hydroxyl group.

[一般式（３）中、Ａ²は２価の連結基または単結合を示す。Ｒ²は置換基を有していてもよいアルキル基または水素原子を表す。] General formula (3)

[In General Formula (3), A ² represents a divalent linking group or a single bond. R ² represents an alkyl group which may have a substituent or a hydrogen atom. ]

The divalent linking group A ² in the general formula (3) is a linking group or a single bond represented by the general formula (6), and preferably a single bond.

General formula (6)

−H ⁴ −J ⁴ −

In general formula (6),
H ⁴ is an ether group, a ketone group, an amide group, or an ester group,
J ⁴ is an alkylene group which may have a substituent, or an arylene group which may have a substituent.

H ^{4 in the} general formula (6) is preferably an ester group.

The alkylene group which may have a substituent in J ⁴ of the general formula (6) and the arylene group which may have a substituent have a substituent in J ¹ of the general formula (4). An alkylene group which may have the same meaning as an arylene group which may have a substituent,
An unsubstituted alkylene group or an unsubstituted phenylene group is preferable, an unsubstituted alkylene group having 1 to 18 carbon atoms is more preferable, and an unsubstituted alkylene group having 2 to 4 carbon atoms is particularly preferable. It is.

R ² in the general formula (3) is an optionally substituted alkyl group or a hydrogen atom, preferably an unsubstituted alkyl group or a hydrogen atom, more preferably a methyl group or a hydrogen atom. An atom, more preferably a hydrogen atom.

  When the polymer dispersant (A) includes a structural unit represented by the general formula (3), it may be a random copolymer or a block copolymer.

<Carbon material (C)>
The carbon material (C) is not particularly limited as long as it is a conductive carbon material, but graphite, carbon black, conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon fibers), fullerene, etc. It can be used alone or in combination of two or more. From the viewpoint of conductivity, availability, and cost, it is preferable to use carbon black.

  Carbon black is a furnace black produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially ketjen black using ethylene heavy oil as a raw material. Channel black that has been rapidly cooled and precipitated, thermal black obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and particularly various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used in combination. Ordinarily oxidized carbon black, hollow carbon and the like can also be used.

  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.

As the specific surface area of the carbon black used increases, the number of contact points between the carbon black particles increases, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) determined from the amount of nitrogen adsorbed is 20 m ² / g or more and 1500 m ² / g or less, preferably 50 m ² / g or more and 1500 m ² / g or less, more preferably 100 m ^2. / G or more and 1500 m ² / g or less are desirable. If carbon black having a specific surface area of less than 20 m ² / g is used, it may be difficult to obtain sufficient conductivity, and carbon black of more than 1500 m ² / g may be difficult to obtain from commercially available materials. is there.

  Further, the particle size of the carbon black to be used is preferably 0.005 to 1 μm, particularly preferably 0.01 to 0.2 μm in terms of primary particle size. However, the primary particle diameter here is a value obtained by averaging the particle diameters measured with an electron microscope.

  Examples of commercially available carbon black include Toka Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Furnace Black), Printex L and the like (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA, Conductex 975 ULTRA, etc. (Columbian manufactured by Furnace Black), # 2350, # 2400B, # 30050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B, etc. (Manufactured by Chemical Co., Furnace Black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, etc. Furnace Black), Ensaco 250G, Ensaco 260G, Ensaco 350G, SuperP-Li, (manufactured by TIMCAL), Ketjen Black EC-300J, EC-600JD (manufactured by Akzo), Denka Black, Denka Black HS-100, FX-35 (Electrochemistry) (Industry company make, acetylene black) etc. are mentioned, However, It is not limited to these. Examples of graphite include natural graphite such as artificial graphite, flake graphite, lump graphite, and earth graphite, but the graphite is not limited thereto, and two or more kinds may be used in combination.

  As the conductive carbon fibers, those obtained by firing from petroleum-derived raw materials are preferable, but those obtained by firing from plant-derived raw materials can also be used. For example, VGCF manufactured by Showa Denko KK manufactured with petroleum-derived raw materials can be used.

<Derivative (D)>
The derivative (D) used in the present invention is preferably an organic dye derivative having an acidic functional group or a triazine derivative having an acidic functional group. In particular, a triazine derivative having an acidic functional group represented by the following general formula (7) or an organic dye derivative having an acidic functional group represented by the following general formula (10) is preferable.

[Triazine derivative having acidic functional group represented by general formula (7)]
General formula (7)

[X ¹ is, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or -X ³ -Y-X ⁴ - represents, X ² and X ^4, each independently, represent -NH- or -O-, X ³ _{is, -CONH -, - SO 2 NH} -, - CH 2 NH -, - NHCO- or -NHSO ₂ - and represent , Y represents an alkylene group that may have a substituent, an alkenylene group that may have a substituent, or an arylene group that may have a substituent, Z represents —SO ₃ M, —COOM, -P (O) (-OM) ₂ or -O-P (O) (-OM) ₂ , M represents one equivalent of a 1 to 3 valent cation, and Q represents -O-R ⁶ , —NH—R ⁶ , a halogen group, —X ¹ —R ⁵ or —X ² —Y—Z, wherein R ⁶ is a hydrogen atom or an alkyl group which may have a substituent. Or the alkenyl group which may have a substituent is represented. u represents an integer of 1 to 4. R ⁵ 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 (8) Represents. ]

General formula (8)

[X ⁵ represents -NH- or -O-, X ⁶ and X ⁷ are each independently, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH- or —CH ₂ NHCOCH ₂ NH—, wherein R ⁷ and R ⁸ are each independently an organic dye residue, a heterocyclic residue which may have a substituent, or an aromatic which may have a substituent. Represents a group ring residue or —Y—Z, and Y and Z have the same meanings as Y and Z in formula (7). ]

In the above, examples of the organic dye residue in R ⁵ , R ⁷ , and R ⁸ include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, phthalocyanine dyes, anthraquinones, diaminodianthraquinones, anthra Anthraquinone dyes such as pyrimidine, flavantron, anthanthrone, indanthrone, pyranthrone, violanthrone, quinacridone dye, dioxazine dye, perinone dye, perylene dye, thioindigo dye, isoindoline dye, isoindolinone Residues such as dyes based on dyes, quinophthalone dyes, selenium dyes, metal complex dyes, and the like. In particular, in order to increase 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, among which an azo dye, a diketopyrrolopyrrole dye, a metal-free phthalocyanine dye, Quinacridone dyes and dioxazine dye residues are preferred because they exhibit excellent dispersibility.

In the above, examples of the heterocyclic residue and aromatic ring residue in R ⁵ , R ⁷ , or R ⁸ include thiophene, furan, pyridine, pyrazole, pyrrole, imidazole, isoindoline, isoindolinone, and benzine. Examples include heterocyclic residues such as imidazolone, benzthiazole, benztriazole, indole, quinoline, carbazole and acridine, and aromatic ring residues such as benzene, naphthalene, anthracene, fluorene, phenanthrene and anthraquinone. In particular, a heterocyclic residue containing any one of S, N, and O heteroatoms is preferable because it exhibits an effect of excellent dispersibility.

  Y in the general formula (7) and the general formula (8) represents an alkylene group, an alkenylene group or an arylene group which may have a substituent, but preferably has 20 or less carbon atoms, and more preferably has 10 or less carbon atoms. . Particularly preferred embodiments include an optionally substituted phenylene group, biphenylene group, naphthylene group or an alkylene group which may have a side chain having 10 or less carbon atoms.

Preferred embodiments of the alkyl group which may have a substituent and the alkenyl group which may have a substituent in R ⁶ are those having 20 or less carbon atoms. More preferably, an alkyl group which may have a side chain having 10 or less carbon atoms is exemplified. Here, the alkyl group having a substituent and the alkenyl group having a substituent are a group in which a hydrogen atom of an alkyl group or an alkenyl group is substituted with a halogen group such as a fluorine atom, a chlorine atom or a bromine atom, a hydroxyl group or a mercapto group. Can be mentioned.

M represents one equivalent of 1 to 3 valent cations, for example, a hydrogen ion (proton), a metal cation, or a quaternary ammonium cation. Moreover, when it has two or more M in the structure (one molecule) of a dispersing agent, M may be only one kind of a proton, a metal cation, and a quaternary ammonium cation, and may be a combination of two or more kinds.
Examples of the metal cation include metal cations such as lithium, sodium, potassium, calcium, barium, magnesium, aluminum, nickel, and cobalt.
The quaternary ammonium cation is a single compound having a structure represented by the general formula (9) or a mixture.

General formula (9)

[R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² each independently has a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. Represents an aryl group which may be substituted. ]

R ⁹ , R ¹⁰ , R ¹¹ , or R ¹² may be the same or different. Moreover, when R < ⁹ >, R < ¹⁰ >, R < ¹¹ > or R < ¹² > has a carbon atom, carbon number is 1-40, Preferably it is 1-30, More preferably, it is 1-20.

  Specific examples of the quaternary ammonium cation include dimethylammonium, trimethylammonium, diethylammonium, triethylammonium, hydroxyethylammonium, dihydroxyethylammonium, 2-ethylhexylammonium, dimethylaminopropylammonium, laurylammonium, stearylammonium and the like. However, it is not limited to these.

［Ｘ⁸は、直接結合、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＣＨ₂ＮＨＣＯＣＨ₂ＮＨ−、−Ｘ⁹−Ｙ−または−Ｘ⁹−Ｙ−Ｘ¹⁰−を表し、Ｘ⁹は、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ₂−を表し、Ｘ¹⁰は、−ＮＨ−または−Ｏ−を表し、Ｙは、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し、Ｚは、−ＳＯ₃Ｍ、−ＣＯＯＭ、−Ｐ（Ｏ）（−ＯＭ）₂または−Ｏ−Ｐ（Ｏ）（−ＯＭ）₂を表し、Ｍは１〜３価のカチオンの一当量を表し、Ｒ¹³は、有機色素残基を表し、ｖは、１〜４の整数を表す。］ [Organic dye derivative having acidic functional group represented by formula (10)]
General formula (10)

[X ⁸ is a direct bond, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH -, - X 9 -Y- or -X ⁹ -Y-X ¹⁰ - represents, X ⁹ _{is, -CONH -, - SO 2 NH} -, - CH 2 NH -, - NHCO- or -NHSO ₂ - represents, X ¹⁰ is, -NH- or -O Y represents an alkylene group that may have a substituent, an alkenylene group that may have a substituent, or an arylene group that may have a substituent, and Z represents —SO ₃ M, -COOM, -P (O) (-OM) ₂ or -O-P (O) (-OM) ₂ , M represents one equivalent of a 1 to 3 valent cation, and R ¹³ represents an organic dye residue. Represents a group, and v represents an integer of 1 to 4. ]

The organic dye residue for R ^{13 has} the same meaning as the organic dye residue for R ⁵ , R ⁷ , or R ⁸ described above. In particular, in order to increase 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, among which an azo dye, a diketopyrrolopyrrole dye, a metal-free phthalocyanine dye, Quinacridone dyes and dioxazine dye residues are preferred because they exhibit excellent dispersibility.

  M in the general formula (10) has the same meaning as M in the general formula (8).

  A method for synthesizing the derivative (D) used in the present invention is not particularly limited, and examples thereof include Japanese Patent Publication No. 39-28884, Japanese Patent Publication No. 45-11026, Japanese Patent Publication No. 45-29755, It can be synthesized by the methods described in JP-B-64-5070, JP-A-2004-217842, and the like.

  In the present invention, it is considered that the derivative (D) mainly functions as a dispersant and also plays a role for creating an electrode film state suitable for improving battery performance.

<Solvent (E)>
Examples of the solvent (E) that may be used in the battery composition of the present invention (sometimes referred to as a solvent or a liquid medium in the present specification) include alcohols, glycols, cellosolves, and amino alcohols. Amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, phosphoric acid esters, ethers, and nitriles.

Among these, 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-methyl-2-pyrrolidone (32.0), hexamethylphosphoric triamide (29.6), dimethyl sulfoxide (48.9), sulfolane (43.3) ), Acetonitrile (37.5), propionitrile (29.7) 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, more preferably 20 or more and 100 or less is excellent in dispersibility of the active material and the conductive assistant. It is preferable. The solvent is selected in view of reactivity with the active material, solubility in the binder resin, and the like. It is preferable to select a solvent having high dispersibility, low reactivity with the active material, and high solubility of the binder resin. Furthermore, from the viewpoint of reducing environmental burdens and economic advantages, when recovering and reusing the solvent discharged in the electrode manufacturing process, it is preferable to use a single solvent instead of a mixed solvent.

  As the solvent satisfying the relative permittivity, the reactivity with the active material, and the solubility of the binder resin and having versatility in a single use, an amide solvent is preferable, and in particular, N, N-dimethylformamide, It is preferable to use an amide aprotic non-aqueous solvent such as N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphoric triamide. In particular, in the use mode of the present invention, N-methyl-2-pyrrolidone is preferable.

<Active material (G)>
When the composition of the present invention is used for a positive electrode mixture or a negative electrode mixture, in addition to the polymer dispersant (A), the carbon material (C), the derivative (D), and the solvent (E), an active material ( As G), a positive electrode active material or a negative electrode active material may be included.

The positive electrode active material for the lithium ion secondary battery is not particularly limited, but metal oxides capable of doping or intercalating lithium ions, metal compounds such as metal sulfides, and conductive polymers are used. be able to.
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, and transition metal sulfide powders such as TiS ₂ and FeS. 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.

The negative electrode active material for the lithium ion secondary battery 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 alloys, silicon alloys, lead alloys, 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.

<Binder resin (F)>
The composition of the present invention preferably further contains a binder resin. Binder resins used 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. In particular, in the use mode of the present invention, polyvinylidene fluoride is preferred.

  Further, the weight average molecular weight of these resins as the binder resin is preferably 10,000 to 1,000,000. When the molecular weight is small, the resistance of the binder may decrease. When the molecular weight is increased, the resistance of the binder is improved, but the viscosity of the binder itself is increased and the workability is lowered.

<Composition for secondary battery>
The composition of the present invention can be used for a positive electrode mixture or a negative electrode mixture. When used for a positive electrode composite or a negative electrode composite, an active material (G) (a positive electrode active material or a positive electrode active material or a composition containing the polymer dispersant (A), a carbon material (C), and a solvent (E)). Negative electrode active material), more preferably, it is preferably used as a positive / negative electrode mixture slurry containing a binder (F). Further, the composition may contain a derivative (D).

The proportion of the active material in the total solid content in the electrode mixture slurry is preferably 80% by weight or more and 99% by weight or less. Further, the proportion of the carbon material (C) as a conductive additive in the total solid content in the electrode mixture slurry is preferably 0.1% by weight or more and 15% by weight or less.
In the present invention, the proportion of the polymer dispersant (A) and the derivative (D) in the mixture slurry is the sum of the weight of the active material (G) and the carbon material (C) as the conductive assistant. It is preferable that it is 0.01 to 7.5 weight% with respect to each. More preferably, it is 0.01 to 5 weight%, More preferably, it is 0.01 to 2.5 weight%. When the derivative (D) is added, the proportion is preferably 1% by weight or more and 80% by weight or less, more preferably 10% by weight or more and 60% by weight or less, based on the total weight of the polymer dispersant (A). . And the ratio of the binder component in the total solid content in the electrode mixture slurry is preferably 1% by weight or more and 10% by weight or less. In addition, the appropriate viscosity of the electrode mixture slurry depends on the method of applying the electrode mixture slurry, but generally it is preferably 100 mPa · s or more and 30,000 mPa · s or less.

  In the composition of the present invention, for example, a carbon material (C) as a conductive auxiliary agent is dispersed in a solvent (E) in the presence of a polymer dispersant (A), and a derivative is added to the dispersion as necessary. (D), an active material (G) (a positive electrode active material or a negative electrode active material), and / or a binder (F) can be mixed and manufactured. The order of addition of each component is not limited to this. Moreover, you may add a solvent further as needed. In the present specification, unless otherwise specified, the “dispersion” is composed of a polymer dispersant (A), a carbon material (C) as a conductive auxiliary agent, and a solvent (E), and a derivative (D). It shall mean the composition for secondary batteries which can contain. In addition, the “mixed material slurry” refers to a composition for a secondary battery obtained by further containing an active material (G) (positive electrode active material or negative electrode active material) and a binder (F) in the “dispersion”. And

  In the production method described above, the polymer dispersant (A), and further, if the derivative (D) is included, the derivative (D) is completely or partially dissolved in the solvent (E), and the solution is used as a conductive auxiliary agent. By adding and mixing the carbon material (C), the polymer dispersant (A), and when the derivative (D) is further included, the derivative (D) is allowed to act (for example, adsorb) on the carbon material (C). , Dispersed in a solvent. The concentration of the carbon material (C) in the dispersion at this time is 1% by weight or more, although depending on the characteristic value of the carbon material such as the specific surface area and surface functional group amount of the carbon material (C) to be used. 50 weight% or less is preferable, More preferably, it is 5 weight% or more and 35 weight% or less. When the concentration of the carbon material (C) is too low, the production efficiency is deteriorated, and when the concentration of the carbon material (C) is too high, the viscosity of the dispersion is remarkably increased, and the dispersion efficiency and the efficiency of the contamination removing process described later The workability of the dispersion may be reduced. In particular, when a step for removing contamination is added, the viscosity of the dispersion is preferably 5 mPa · s or more and 10,000 mPa · s or less, more preferably 5,000 mPa · s or less, and still more preferably 3,000 mPa · s or less. And

The dispersed particle size of the carbon material (C) as the conductive auxiliary agent in the secondary battery composition is 0.03 μm or more and 2 μm or less, preferably 0.05 μm or more and 1 μm or less, more preferably 0.05 μm. As mentioned above, it is desirable that it is 0.5 micrometer or less.
The dispersed particle diameter of the carbon material (C) in the present specification is the particle diameter (D50) at 50% when the volume ratio of the particles is integrated from the small particle diameter in the volume particle size distribution. It is a value measured by a particle size distribution meter of a dynamic light scattering method (in the examples of this specification, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.).

  In addition, as a device for dispersing the polymer dispersant (A) and the derivative (D) in the solvent while acting (for example, adsorbing) the derivative (D) on the carbon material (C), A disperser used for pigment dispersion or the like can be used. For example, mixers such as dispersers, homomixers, planetary mixers, homogenizers ("Clearmix" manufactured by M Technique, PRIMIX "Fillmix", etc.), paint conditioners (manufactured by Red Devil), ball mills, sand mills ( Media type dispersers such as “Dynomill” manufactured by Shinmaru Enterprises, Inc.), Attritor, Pearl Mill (“DCP Mill” manufactured by Eirich), Coball Mill, etc., Wet Jet Mill (“Genus PY” manufactured by Genus, Sugino Machine Co., Ltd.) Media-less dispersers such as “Starburst” manufactured by Nanomizer, “Nanomizer” manufactured by Nanomizer, etc., “Claire SS-5” manufactured by M Technique, and “MICROS” manufactured by Nara Machinery Co., other roll mills, etc. It is not limited to. Moreover, as the disperser, it is preferable to use a disperser that has been subjected to a metal contamination prevention treatment from the disperser.

  For example, when using a media-type disperser, the agitator and vessel are dispersed using a ceramic or resin disperser, or the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. It is preferable to use a machine. And as a media, it is preferable to use ceramic beads, such as glass beads, zirconia beads, and alumina beads, and among them, the use of zirconia beads is preferable. 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. Further, in the case of a positive or 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 type disperser.

  In addition, it is preferable to include a step of removing contaminants such as metal foreign matters during dispersion. Carbon black, graphite, and carbon materials such as carbon fiber often contain metallic foreign matters derived from their manufacturing processes (as line contamination and catalysts). It is very important to prevent short circuit. In the present invention, due to the effect of the polymer dispersant (A), the aggregation of the carbon materials (C) is well loosened, and the viscosity of the dispersion is low, so even when the carbon material concentration in the dispersion is high, Metal foreign matter can be removed efficiently. Examples of methods for removing metallic foreign substances include iron removal with a magnet, filtration, and centrifugation.

  As a method for adding the binder (F), when the polymer dispersant (A) is further included and the derivative (D) is contained, the carbon material (C) as a conductive auxiliary agent is dispersed in a solvent in the presence of the derivative (D). A method of adding and dissolving a solid binder component while stirring the resulting dispersion is mentioned. Moreover, what melt | dissolved the binder in the solvent is produced beforehand and the method of mixing with the said dispersion is mentioned. Further, after the binder (F) is added to the dispersion, the dispersion treatment may be performed again by the dispersion apparatus. Further, when the polymer dispersant (A) and the derivative (D) are further included, when the carbon material (C) as the conductive assistant is dispersed in the solvent (E) in the presence of the derivative (D), the binder ( A part or all of F) may be added at the same time to carry out the dispersion treatment.

  As a method for adding the active material (G) (positive electrode active material or negative electrode active material), the polymer dispersant (A), and when the derivative (D) is further included, A method in which a positive electrode active material or a negative electrode active material is added and dispersed while stirring a dispersion formed by dispersing the carbon material (C) in the solvent (E) can be mentioned. In addition, when the polymer dispersant (A) and the derivative (D) are further included, when the carbon material as the conductive additive is dispersed in the solvent in the presence of the derivative (D), the positive electrode active material or the negative electrode active material A part or all of the above can be added at the same time to carry out the dispersion treatment. Further, when the polymer dispersant (A) and the derivative (D) are further included, a dispersion obtained by dispersing the carbon material (C) as a conductive additive in the solvent (E) in the presence of the derivative (D). There is a method in which the binder component is added as a solid or a solution while stirring and then the positive electrode active material or the negative electrode active material is added and dispersed. Further, when the polymer dispersant (A), the carbon material (C), the solvent (E), the active material (G), the binder (F) and the derivative (D) are included, the derivative (D) is mixed, and at the same time Distributed processing is also possible. As an apparatus for mixing and dispersing, the above-described dispersers used for ordinary pigment dispersion and the like can be used.

The size of the active material (G) to be used is preferably in the range of 0.05 to 100 μm, and more preferably in the range of 0.1 to 50 μm, in terms of average particle size. The average particle diameter of an active material here is an average value of the major axis of each primary particle in an image observed with a scanning electron microscope (SEM). However, in order to increase the reaction area of the active material, an active material may be an aggregate (secondary particle) that is obtained by granulating fine primary particles after the synthesis process or after synthesis. Measures the major axis of the secondary particles and sets the average particle size of the active material.
The ratio of the average particle diameter of the active material (G) to the dispersed particle diameter (D50) of the carbon material (C) described above (average particle diameter of the active material (G) / dispersed particle diameter of the carbon material (C) (D50 )), It is preferably 2 or more and 100 or less. More preferably, it is 9 or more and 70 or less. Particularly preferably, it is 10 or more and 50 or less.

  When the average particle size / the dispersed particle size (D50) of the carbon material (C) is 2 or more and 100 or less, the battery performance is improved. Considering this, it can be inferred that this is due to a change in the state of the coating film when the mixture slurry dries. During drying, the distance between particles in the slurry (between the active material and the carbon material) gradually decreases and eventually aggregates, but this aggregation proceeds in a manner that minimizes the interfacial energy of the aggregates. I think that the. At this time, if the particle sizes of the active material and the carbon material are within a certain range, it is considered that the carbon material is disposed so as to cover the surface of the active material, and the interfacial energy is reduced at that time. As a result, when the dispersed particle size of the active material / carbon material is 2 to 100, the carbon material is disposed so as to cover the surface of the active material, and a uniform and strong conductive path is formed in the electrode film. It seems that battery performance will improve.

As described above, the composition of the present invention can be usually produced, distributed and used as a dispersion (liquid) containing a solvent, a paste or the like. This is because even if the conductive auxiliary agent or active material and the dispersing agent are mixed in a dry powder state, the dispersing agent cannot be uniformly applied to the conductive auxiliary agent or the active material. This is because, by dispersing the conductive additive and the active material in the solvent in the presence of, the dispersant can be made to act uniformly on the conductive additive and the active material. Further, as described below, when the electrode mixture layer is formed on the current collector, it is preferable to apply the liquid dispersion as uniformly as possible and dry it.
However, for example, a dispersion produced by a liquid phase method is used to remove the solvent once to make a dry powder for reasons of transportation cost, etc., and then re-disperse the dry powder with an appropriate solvent. You may use for formation of. Therefore, the composition of the present invention is not limited to a liquid dispersion, and may be a composition in a dry powder state.

<Electrode for secondary battery>
Of the composition for a secondary battery of the present invention, the mixture slurry can be applied and dried on a current collector to form a mixture layer to obtain a secondary battery electrode.

(Current collector)
The material and shape of the current collector used for the electrode are not particularly limited, and those suitable for various secondary batteries can be appropriately selected. For example, examples of the material for the current collector include metals and alloys such as aluminum, copper, nickel, titanium, and stainless steel. In general, a flat foil is used as the shape, but a roughened surface, a perforated foil, or a mesh current collector can also be used.

  There is no restriction | limiting in particular as a method of apply | coating a mixture slurry and the composition for base layer formation on a collector, A well-known method can be used. Specific examples include die coating method, dip coating method, roll coating method, doctor coating method, knife coating method, spray coating method, gravure coating method, screen printing method or electrostatic coating method, and the like. Examples of methods that can be used include standing drying, blower dryers, hot air dryers, infrared heaters, and far-infrared heaters, but are not particularly limited thereto.

  Moreover, you may perform the rolling process by a lithographic press, a calender roll, etc. after application | coating. 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.

<Secondary battery>
A secondary battery can be obtained by using the above electrode for at least one of a positive electrode and a negative electrode. Secondary batteries include lithium ion secondary batteries, sodium ion secondary batteries, magnesium secondary batteries, alkaline secondary batteries, lead storage batteries, nickel cadmium batteries, sodium sulfur secondary batteries, lithium air secondary batteries, fuel A lithium ion secondary battery, an alkaline secondary battery, and a fuel cell, more preferably a lithium ion secondary battery and an alkaline secondary battery, and particularly preferably a lithium ion secondary battery. It is. In each secondary battery, conventionally known electrolytes, separators, and the like can be appropriately used.

(Electrolyte)
A case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, an electrolyte containing lithium dissolved in a non-aqueous solvent is used. As electrolytes, 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, or LiBPh _4, but are not limited thereto.

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

  Furthermore, the electrolytic solution can be used in the form of a polymer electrolyte that is held in a polymer matrix and is in the form of a gel. 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, and a polysiloxane having a polyalkylene oxide segment.

(separator)
Examples of the separator include, but are not limited to, a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, a polyamide nonwoven fabric and those obtained by subjecting them to a hydrophilic treatment.

(Battery structure / configuration)
The structure of the lithium ion secondary battery using the composition of the present invention is not particularly limited, but is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary, a paper type, a cylindrical type, a button type, It can be made into various shapes according to the purpose of use, such as a laminated type.

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

[Average particle size of active material]
The average particle diameter of the active material was calculated from an observation image obtained from a scanning electron microscope (SEM). Here, for LCO, LMO, LFP, artificial graphite, and LTO, the major axis of 100 primary particles was measured and calculated from the average value. For NMC, the major axis of 100 secondary particles was measured and calculated from the average value.

<Synthesis of precursor>
(Synthesis example of precursor (a-1))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, 200.0 parts of N-methyl-2-pyrrolidone, 149.0 parts (1 equivalent) of isophorone diisocyanate (IPDI), and 5-amino-2 -Benzimidazolinone (5ABI) 100.0 parts (1 equivalent) was charged, replaced with nitrogen gas, and the reaction was continued at room temperature for 3 hours. Then, the NCO value was measured and it was confirmed that the reaction rate was 95%. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 30%. Then, it cooled and obtained the precursor (a-1) solution.

(Synthesis example of precursors (a-2), (a-7), (a-8))
The compounding composition shown in Table 1 was synthesized in the same manner as the precursor (a-1), and the precursor (a-2) solution, the precursor (a-7) solution, and the precursor (a-8) solution were prepared. I got each.

(Synthesis example of precursor (a-3))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, 200.0 parts of N-methyl-2-pyrrolidone, 69.6 parts of isophorone diisocyanate (1 equivalent), and 5- (3′-hydroxy-) 20.0-Naphtylamino) benzimidazolinone (HNBI) 100.0 parts (1 equivalent) was charged and replaced with nitrogen gas. The reaction layer was brought to 90 ° C., 0.01 part of U-810 (manufactured by Nitto Kasei) was charged, and the reaction was continued at 100 ° C. for 3 hours. Then, the NCO value was measured and it was confirmed that the reaction rate was 95%. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 30%. Then, it cooled and obtained the precursor (a-3) solution.

(Synthesis example of precursor (a-4))
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 500.0 parts of ethyl acetate, 100.0 parts of 5-amino-2-benzimidazolinone (5ABI), and 10.0 parts of triethylamine. The mixture was cooled to 5 ° C. and stirred. Subsequently, the gas was replaced with nitrogen gas, and a mixed solution of 200.0 parts of ethyl acetate and 198.9 parts of triphosgene was added dropwise. After stirring for 10 minutes at the same temperature, the temperature was raised and the mixture was refluxed for 4 hours. After cooling, the product was filtered, washed with ethyl acetate, and then dried under reduced pressure to obtain 82.2 parts of precursor (a-4). N-methyl-2-pyrrolidone was added to and dissolved in the obtained precursor (a-4). V. = 30% and a precursor (a-4) solution was obtained.

(Synthesis example of precursor (a-5))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, 1000.0 parts of acetone, 100.0 parts of 5-carboxy-2-benzimidazolinone (5CBI), 10.0 parts of N, N-dimethylformamide And stirred at room temperature. Subsequently, the gas was replaced with nitrogen gas, and 133.6 parts of thionyl chloride was added dropwise. After stirring for 10 minutes at the same temperature, the temperature was raised and the mixture was heated to reflux for 3 hours. After cooling, the product was filtered, washed with acetone, and then dried under reduced pressure to obtain 77.8 parts precursor (a-5). (Dry powder)

(Synthesis example of precursor (a-6))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, acetone 1200.0 parts, 5-sulfo-2-benzimidazolinone (5SBI) 100.0 parts, N, N-dimethylformamide 15.0 parts And stirred at room temperature. Subsequently, the gas was replaced with nitrogen gas, and 111.0 parts of thionyl chloride was added dropwise. After stirring for 10 minutes at the same temperature, the temperature was raised and the mixture was refluxed for 4 hours. After cooling, the product was filtered, washed with acetone, and then dried under reduced pressure to obtain 76.0 parts of precursor (a-6). (Dry powder)

(Synthesis example of precursor (a-9))
By the composition shown in Table 1, it synthesize | combined by the method similar to a precursor (a-5), and obtained the precursor (a-9) solution.

IPDI: isophorone diisocyanate TDI: toluene diisocyanate 5ABI: 5-amino-2-benzimidazolinone HNBI: 5- (3′-hydroxy-2′-naphthylamino) benzimidazolinone 5 carboxy BI (5CBI): 5-carboxy-2 -Benzimidazolinone 5 sulfo BI (5SBI): 5-sulfo-2-benzimidazolinone 5A6MBI: 5-amino-6-methoxy-2-benzimidazolinone 5A1MID: 5-amino-1-methoxyindene 4 carboxy BI (4CBI) ): 4-carboxy-2-benzimidazolinone U-810: “Product name Neostan U-810” dioctyltin manufactured by Nitto Kasei Co., Ltd.

<Synthesis of polymer precursor>
(Synthesis example of polymer precursor (b-1))
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, a stirrer, and a dropping funnel was charged with 100.0 parts of N-methyl-2-pyrrolidone and replaced with nitrogen gas. The temperature of the reaction layer was raised to 100 ° C., and a mixture of 111.5 parts of hydroxyethyl acrylate, 100.0 parts of styrene, and 10.2 parts of azobisisobutyronitrile (AIBN) was dropped into the reaction vessel over 2 hours. A polymerization reaction was performed. After completion of the dropwise addition, the reaction was continued for further 3 hours, and then 1.2 parts of AIBN was added. The reaction was further continued for 1 hour, and then 1.2 parts of AIBN was added, and the reaction was continued for another hour. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 30%. Then, it cooled and obtained the precursor (b-1) solution.

(Synthesis example of polymer precursors (b-2), (c-1) to (c-3), (d-1))
The compounding compositions shown in Table 2 were synthesized in the same manner as the polymer precursor (b-1) to obtain precursor (b-2) to (d-1) solutions.

<Synthesis of modified polymer precursor>
(Synthesis example of modified polymer precursor (e-1))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, 200.0 parts of N-methyl-2-pyrrolidone and 100.0 parts of PVA103 (manufactured by Kuraray) were charged and replaced with nitrogen gas. The temperature of the reaction layer was raised to 100 ° C., 65.4 parts of phthalic anhydride and 1.0 part of DBU (diazabicycloundecene) were added, and the reaction was continued for 7 hours. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 30%. Then, it cooled and the modified | denatured polymer precursor (e-1) solution was obtained.

(Synthesis example of modified polymer precursor (e-2))
The composition shown in Table 3 was synthesized in the same manner as the modified polymer precursor (e-1) to obtain a modified polymer precursor (e-2) solution.

(Synthesis Example of Modified Polymer Precursor (e-3))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, N.I. V. = 30% polymer precursor (b-1) solution 333.3 parts (100 parts of polymer precursor b-1) were charged and replaced with nitrogen gas. The temperature of the reaction layer was raised to 100 ° C., 6.7 parts of phthalic anhydride and 1.0 part of DBU were added, and the reaction was continued for 7 hours. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 30%. Then, it cooled and the modified polymer precursor (e-3) solution was obtained.

(Synthesis example of modified polymer precursor (e-4))
The composition shown in Table 3 was synthesized in the same manner as the modified polymer precursor (e-3) to obtain a modified polymer precursor (e-4) solution.

PVA103: “Poval PVA103” manufactured by Kuraray Co., Ltd., polyvinyl alcohol PVA505: “Poval PVA505” manufactured by Kuraray Co., Ltd., polyvinyl alcohol DBU: Diazabicycloundecene

<Synthesis of Polymer Dispersant (A-1) to (A-10)>
(Synthesis Example of Polymer Dispersant (A-1))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, N.I. V. = 306.0% of precursor (a-1) solution 1366.0 parts (precursor (a-1) 409.8 parts) was charged and replaced with nitrogen gas. The reaction layer was heated to 100 ° C., 100.0 parts of PVA103 and 1.0 part of U-810 (manufactured by Nitto Kasei) were added, and the reaction was continued for 7 hours. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 20%. Then, it cooled and the polymer dispersing agent (A-1) solution was obtained.

(Synthesis example of polymer dispersant (A-2), (A-8), (A-9))
The composition shown in Table 4 was synthesized in the same manner as the polymer dispersant (A-1) to obtain a polymer dispersant (A-2), (A-8), and (A-9) solution. .

(Synthesis Example of Polymer Dispersant (A-3))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, N.I. V. = 307.7% precursor (a-3) solution 737.7 parts (precursor (a-3) 221.3 parts) was charged and replaced with nitrogen gas. The temperature of the reaction layer was raised to 100 ° C., 333.3 parts of the polymer precursor (b-1) solution (100.0 parts of polymer precursor (b-1)) and 1.0 part of DBU were added and reacted for 7 hours. Continued. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 20%. Then, it cooled and the polymer dispersing agent (A-3) solution was obtained.

(Synthesis Example of Polymer Dispersant (A-4))
The compounding composition shown in Table 4 was synthesized in the same manner as the polymer dispersant (A-3) to obtain a polymer dispersant (A-4) solution.

(Synthesis Example of Polymer Dispersant (A-5))
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 600.0 parts of acetone, 35.0 parts of triethylamine, and 347.1 parts of precursor (a-5), and replaced with nitrogen gas. The reaction layer was heated to 50 ° C., 100.0 parts of PVA103 was added, and the reaction was continued for 5 hours. Subsequently, 1300.0 parts of water was added to the reaction vessel, the precipitate was filtered, washed with water, and then dried under reduced pressure to obtain 175.8 parts of a polymer dispersant (A-5). N-methyl-2-pyrrolidone was added to and dissolved in the obtained polymer dispersant (A-5). V. = 20% to obtain a polymer dispersant (A-5) solution.

(Synthesis Example of Polymer Dispersant (A-6))
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 600.0 parts of acetone, 50.0 parts of pyridine, and 59.7 parts of precursor (a-6), and replaced with nitrogen gas. The temperature of the reaction layer was raised to 50 ° C., 333.3 parts of polymer precursor (d-1) solution (100.0 parts of polymer precursor (d-1)) was added, and the reaction was performed for 7 hours. Subsequently, 1300.0 parts of water was added to the reaction vessel, the precipitate was filtered, washed with water, and then dried under reduced pressure to obtain 108.4 parts of a polymer dispersant (A-6). N-methyl-2-pyrrolidone was added to the obtained polymer dispersant (A-6) and dissolved. V. = 20% to obtain a polymer dispersant (A-6) solution.

(Synthesis Example of Polymer Dispersant (A-7))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, 600.0 parts of acetone, 35.0 parts of triethylamine, 73.2 parts of 5-carboxy-2-benzimidazolinone (5CBI), N, N- 0.8 part of dimethylformamide was charged and stirred at room temperature. Subsequently, the gas was replaced with nitrogen gas, and 9.8 parts of thionyl chloride was added dropwise. After stirring for 10 minutes at the same temperature, the temperature was raised and the mixture was heated to reflux for 3 hours to obtain 333.3 parts of polymer precursor (d-1) solution (100.0 parts of polymer precursor (d-1)). For 5 hours. Subsequently, 1300.0 parts of water was added to the reaction vessel, the precipitate was filtered, washed with water, and then dried under reduced pressure to obtain 102.3 parts of a polymer dispersant (A-7). N-methyl-2-pyrrolidone was added to and dissolved in the obtained polymer dispersant (A-7). V. = 20% to obtain a polymer dispersant (A-7) solution.

(Synthesis Example of Polymer Dispersant (A-10))
The compounding composition shown in Table 4 was synthesized in the same manner as the polymer dispersant (A-5) to obtain a polymer dispersant (A-10) solution.

(Synthesis Example of Polymer Dispersant (A-11))
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer, N.I. V. = 30% polymer precursor (c-1) solution 333.3 parts (polymer precursor (c-1) 100.0 parts), 5ABI 124.8 parts were charged and replaced with nitrogen gas. The reaction layer was heated to 150 ° C. and the reaction was continued for 7 hours. Thereafter, N-methyl-2-pyrrolidone was added for dilution. V. = 20%. Then, it cooled and the polymer dispersing agent (A-11) solution was obtained.

(Synthesis example of polymer dispersants (A-12) to (A-17))
The compounding compositions shown in Table 5 were synthesized in the same manner as the polymer dispersant (A-11) to obtain polymer dispersants (A-12) to (A-17) solutions.

  The structures of the obtained polymer dispersants (A-1) to (A-17) are shown together in Table 6.

5CBI: 5-carboxy-2-benzimidazolinone 5ABI: 5-amino-2-benzimidazolinone

<Production of battery composition (dispersion)>
[Example 1]
(Production of dispersion (P-1))
While stirring 80.0 parts of N-methyl-2-pyrrolidone as a solvent with a mixer, 4 parts of the polymer dispersant (A-1) solution (solid content 20%) was added and dissolved by stirring. Next, after adding 16 parts of carbon materials (Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.)) and mixing with a mixer, dispersion was further performed with a sand mill to obtain a dispersion (P-1).

[Examples 2 to 17, Comparative Examples 1 to 3]
(Production of dispersions (P-2) to (P-23))
Dispersions (P-2) to (P-23) were obtained in the same manner as the dispersion (P-1) except that the materials and blending amounts were changed according to the composition shown in Table 7.

<Evaluation of battery composition (dispersion)>
(Dispersibility evaluation)
The dispersion particle size was used as an index for evaluating the dispersibility of the dispersion. Dispersion particle size is measured by using a dynamic light scattering particle size distribution meter ("MICROTRACK UPA" manufactured by Nikkiso Co., Ltd.). The particle diameter (D50) at 50% was determined. This particle size (D50) corresponds to the dispersed particle size of the carbon material (C).
A sample solution for measurement was prepared as follows. While dispersing 100 g of N-methyl-2-pyrrolidone, 1 to 4 drops of the obtained battery composition (dispersion) was added to the liquid, and the mixture was stirred at 1,000 rpm for 5 minutes. The sample liquid for measurement was set in the above particle size distribution meter, and after confirming that the loading index (laser scattering intensity) was in the range of 0.8 to 1.2, the dispersed particle size was measured. When the loading index exceeded 1.2 in the above preparation method, the sample solution was appropriately diluted with N-methyl-2-pyrrolidone so as to be in the range of 0.8 to 1.2. The measurement time was 60 seconds / once, and the average value of the values obtained by three consecutive measurements was used.
The smaller the value, the better the dispersibility and the more uniform and good dispersion. The dispersion particle size of the dispersion was measured twice immediately after production of various dispersions and after the dispersion was stored at 50 ° C. for 10 days.
“Storage stability” means the ratio of “dispersion particle size of dispersion stored at 50 ° C. for 10 days / dispersion particle size of dispersion immediately after production”. The smaller the deviation from 1.00, the more storage stability It is excellent in performance. The results are shown in Table 7.

HS-100: 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.
Super-P Li: “Super-P Li,” furnace black, manufactured by TIMCAL. Primary particle diameter 40 nm, specific surface area 62 m ² / g.
PVA103: “Poval PVA103” manufactured by Kuraray Co., Ltd., polyvinyl alcohol 5ABI: 5-amino-2-benzimidazolinone

Derivatives (D-1), (D-2)

  Regarding the dispersibility of the carbon material dispersion of the present invention, as shown in Table 7, all of the dispersions have good dispersibility of the carbon material, and are dispersions in which the carbon material is uniformly dispersed. confirmed. In addition, it was confirmed that the carbon material dispersions in the examples were excellent in storage stability as compared with the comparative examples in that the dispersion particle size immediately after production and the dispersion particle size after storage at 50 ° C. for 10 days were small. It was.

<Manufacture of battery composition (positive electrode mixture slurry)>
[Example 21]
(Production of positive electrode mixture slurry (S-1))
Dispersion (P-1) 13.8 parts (13.8 wt%) (Polymer Dispersant A-1 0.11 wt% (solid content) and carbon material (C) 2.2 wt% (solid content) ) And N-methyl-2-pyrrolidone solution of W # 1100 (solid content 12 wt%) as a binder (17.5 parts (17.5 wt%)) (W # 1100 2.1 wt%, N -Methyl-2-pyrrolidone (containing 15.4% by weight) is collected and mixed with a disper to homogenize. While stirring this mixed solution with a disper, 68.6 parts (68.6 wt%) of LiCoO ₂ (hereinafter abbreviated as LCO) having an average particle diameter of 6.7 μm was gradually added as a positive electrode active material, A positive electrode mixture slurry (S-1) was produced by further adding N-methyl-2-pyrrolidone as a solvent so that the solvent was 27.0% by weight and mixing with a disper for 30 minutes.

[Examples 21 to 40, Comparative Examples 4 to 6]
(Production of positive electrode mixture slurry (S-2) to (S-23))
Except having changed into the material shown in Table 9, it carried out similarly to the positive mix slurry (S-1), and manufactured the positive mix slurry (S-2)-(S-23).

# 1100: KF polymer W # 1100 (manufactured by Kureha), polyvinylidene fluoride (PVDF), molecular weight 280,000.
# 7200: KF polymer W # 7200 (manufactured by Kureha): polyvinylidene fluoride (PVDF), molecular weight 630,000.
LCO: LiCoO ₂ having an average particle diameter of 6.7 μm
NMC: LiNi _(1/3) Mn _(1/3) Co _(1/3) O _{2 with an} average particle size of 15 μm
LMO: LiMn ₂ O _{4 having} an average particle diameter of 12 μm
LFP-01: LiFePO ₄ having a carbon coat layer on the surface and an average particle diameter of 1 μm
LFP-02: LiFePO ₄ having a carbon coat layer on the surface and an average particle diameter of 3 μm

<Manufacture of battery composition (negative electrode mixture slurry)>
[Example 41]
(Manufacture of negative electrode mixture slurry (S-24))
Dispersion (P-4) 11.3 parts and 28.8 parts of an N-methyl-2-pyrrolidone solution of W # 7200 (solid content 8 wt%) as a binder were mixed with a disper and homogenized, and then the liquid As a negative electrode active material, 55.8 parts of artificial graphite having an average particle diameter of 15 μm was gradually added. Next, N-methyl-2-pyrrolidone was added and mixed as a solvent so that the solid content of the mixture slurry was 60% by weight to produce a negative electrode mixture slurry (S-24).

[Example 42]
(Manufacture of negative electrode mixture slurry (S-25))
After 17.8 parts of dispersion (P-18) and 33.8 parts of an N-methyl-2-pyrrolidone solution of W # 7200 (8% solids) as a binder were mixed with a disper and homogenized, While stirring, 51.3 parts of Li ₄ Ti ₅ O ₁₂ (hereinafter sometimes abbreviated as LTO) having an average particle diameter of 5 μm was gradually added as a negative electrode active material. Next, N-methyl-2-pyrrolidone was added and mixed as a solvent so that the solid content of the mixture slurry would be 57% to produce a negative electrode mixture slurry (S-25).

[Comparative Example 7]
(Manufacture of negative electrode mixture slurry (S-26))
A negative electrode mixture slurry (S-26) was prepared in the same manner as the negative electrode mixture slurry (S-24) except that the materials shown in Table 10 were changed.

[Comparative Examples 8 and 9]
(Production of negative electrode mixture slurry (S-27), (S-28))
Except having changed into the material shown in Table 10, it carried out similarly to the negative mix slurry (S-25), and adjusted the negative mix slurry (S-27) and (S-28).

Artificial graphite: Artificial graphite with an average particle size of 15 μm LTO: Li ₄ Ti ₅ O _{12 with an} average particle size of 5 μm

<Evaluation of battery composition (positive electrode mixture slurry, negative electrode mixture slurry)>
(Dispersibility evaluation (particle size))
It was carried out by evaluating the particle size with a grind gauge (according to JIS K5600-2-5). The smaller the numerical value, the better the dispersibility and the more uniform and good dispersion. In addition, the particle size measurement of the composite slurry was measured immediately after the production of various slurries and after the slurry was stored at 50 ° C. for 3 days. In the measurement, the particle size was measured immediately after slurry production and after defoaming with a planetary defoaming device. Moreover, about the mixed material slurry preserve | saved for 3 days at 50 degreeC, after re-stirring with a disper, after carrying out defoaming with a planetary rotation type defoaming apparatus, the particle size was measured.
“Storage stability” means the ratio of “particle size of composite slurry stored at 50 ° C. for 3 days / particle size of composite slurry immediately after production”, and the smaller the deviation from 1, the better the storage stability. Indicates that The results are shown in Tables 11 and 12.

<Manufacture of secondary batteries (coin-type batteries)>
[Example 43]
The positive electrode mixture slurry (S-1) is applied onto a 20 μm thick aluminum foil serving as a current collector using a doctor blade so that the thickness of the electrode after the coating film is dried is 100 μm. A film was prepared and dried in a drying furnace at 120 ° C. to obtain a coated product. This was further subjected to a rolling process by a roll press to produce a positive electrode having a thickness of 85 μm.
The obtained positive electrode was punched into a diameter of 16 mm as a working electrode, and a metal lithium foil was used as a counter electrode. A porous separator made of polypropylene is laminated between the working electrode and the counter electrode, and the electrolyte solution (a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a ratio of 1: 1 (volume ratio) is mixed with LiPF ₆ at a concentration of 1M. A coin-type battery was manufactured in such a way that the gap was filled with the dissolved non-aqueous electrolyte solution). The coin-type battery was produced in a glove box substituted with argon gas.

[Examples 44 to 62, Comparative Examples 10 to 12]
A positive electrode and a coin-type battery were prepared in the same manner as in Example 43 except that the positive electrode mixture slurry shown in Table 13 was changed.

[Example 63]
(Manufacture of secondary battery electrode (negative electrode))
The negative electrode mixture slurry (S-24) was applied onto a 20 μm thick aluminum foil serving as a current collector using a doctor blade so that the thickness of the electrode after drying of the coated film would be 80 μm. A film was prepared and dried in a drying furnace at 120 ° C. to obtain a coated product. This was further subjected to a rolling process by a roll press to produce a negative electrode having a thickness of 70 μm.
The obtained negative electrode was punched into a diameter of 16 mm as a working electrode, and a metal lithium foil was used as a counter electrode. A porous separator made of polypropylene is laminated between the working electrode and the counter electrode, and the electrolyte solution (a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a ratio of 1: 1 (volume ratio) is mixed with LiPF ₆ at a concentration of 1M. A coin-type battery was manufactured in such a way that the gap was filled with the dissolved non-aqueous electrolyte solution). The coin-type battery was produced in a glove box substituted with argon gas.

[Example 64, Comparative Examples 13 to 15]
A negative electrode and a coin-type battery were prepared in the same manner as in Example 63 except that the negative electrode mixture slurry shown in Table 14 was changed.

<Evaluation of secondary battery (coin-type battery)>
(Cycle characteristics)
About the obtained secondary battery (coin type battery), charging / discharging measurement was performed using the charging / discharging apparatus (SM-8 by Hokuto Denko). When the active material to be used was LiCoO ₂ , constant current charging was continued to a charge end voltage of 4.3 V at a charging current of 1.7 mA. After the battery voltage reached 4.3 V, constant current discharge was performed at a discharge current of 1.7 mA until the discharge end voltage of 2.8 V was reached. These charge / discharge cycles are defined as one cycle, and 50 cycles of charge / discharge are repeated to obtain “discharge capacity maintenance rate = discharge capacity at the 50th cycle / discharge capacity at the first cycle”, and according to the following criteria depending on the discharge capacity maintenance rate. Judged. The results are shown in Tables 13 and 14.
A: “Discharge capacity maintenance rate is 95% or more”
○: “Discharge capacity maintenance rate is 90% or more and less than 95%”
Δ: “Discharge capacity maintenance ratio is 85% or more and less than 90%”
×: “Discharge capacity maintenance rate is less than 85%”

Moreover, when the active material to be used is LiMn ₂ O ₄ , the case of LiCoO ₂ except that the charge current is 1.0 mA, the charge end voltage is 4.3 V, the discharge current is 1.0 mA, and the discharge end voltage is 3.0 V. Similarly, the cycle characteristics were measured.

When the active material used is LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , the charging current is 2.0 mA, the charging end voltage is 4.3 V, the discharging current is 2.0 mA, and the discharging end voltage is 3. The cycle characteristics were measured in the same manner as LiCoO ₂ except that the voltage was 0V.

Further, the active material to be used, in the case of LiFePO _4, the charging current 1.0 mA, charge end voltage 4.2 V, the discharge current 1.0 mA, except for using discharge end voltage 2.0 V, in the case of LiCoO ₂ Similarly, the cycle characteristics were measured.

  As shown in Tables 13 and 14, it was confirmed that the composite slurry according to the present invention was a composition excellent in dispersibility of the carbon material (conductive auxiliary agent) and the active material. In particular, it was confirmed that the dispersion of the present invention had a small change in particle size when stored at 50 ° C. for 3 days compared with the comparative example, and was excellent in storage stability.

  Moreover, in the battery using the electrode for secondary batteries formed from the composition for secondary battery electrode formation of this invention, it became clear that it is excellent in cycling characteristics (discharge capacity maintenance factor) with respect to the comparative example. Moreover, when using the polymer dispersing agent which introduce | transduced the structure of General formula (2) into PVA using IPDI (mixture slurry (S-1,2,8,9)), resin and a CB dispersion are used. In the case where a pigment derivative was used in combination (mixture slurry (S-18, 19)), this effect was remarkable, and it was confirmed that good cycle characteristics were obtained. Although the reason for the effect of improving the cycle characteristics in the examples is not clear, the use of the resin of the present invention has the effect of improving the dispersion stability of the carbon material dispersion and the mixture slurry. The presence of the resin in the vicinity of the surface of the carbon material and the active material has a favorable effect on the material distribution after drying, such as the formation of a conductive path, when a coated material using a mixture slurry is produced. Alternatively, it is inferred that the cycle characteristics are improved by increasing the film strength.

Claims (10)

A composition for a secondary battery comprising a polymer dispersant (A) having a repeating unit represented by the following general formula (1) and a carbon material (C).
General formula (1)

[In general formula (1),
A ¹ represents a divalent linking group (excluding those containing a triazine ring) or a single bond.
D ¹ represents the structure represented by the general formula (2).
R ¹ represents an alkyl group or a hydrogen atom. ]

General formula (2)

[In general formula (2),
E ¹ , E ² , E ³ , and E ⁴ each independently have an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. Represents a good aryl group, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or a hydrogen atom, and among E ¹ , E ² , E ³ and E ⁴ One of them is a bond with A ¹ .
G ¹ and G ² each independently represent —N (R ³ ) —, —O—, or —CH ₂ —, and R ³ represents an alkyl group or substituent which may have a substituent. An alkenyl group which may have a substituent, an aryl group which may have a substituent, a heteroaryl group which may have a substituent, an oxyalkyl group which may have a substituent, or hydrogen Represents an atom.
G ³ represents —C (═O) —, —C (═S) —, or —CH (OCH ₃ ) —. ]   The composition for a secondary battery according to claim 1, wherein the polymer dispersant (A) has a repeating unit having a hydroxyl group. The composition for a secondary battery according to claim 2, wherein the repeating unit having a hydroxyl group is represented by the following general formula (3).
General formula (3)

[In General Formula (3), A ² represents a divalent linking group or a single bond. R ² represents an alkyl group which may have a substituent or a hydrogen atom. ]   The composition for a secondary battery according to any one of claims 1 to 3, wherein the polymer dispersant (A) has a weight average molecular weight of 15,000 or more and 100,000 or less.   Furthermore, at least 1 sort (s) (D) chosen from the group which consists of the organic pigment derivative which has an acidic functional group, and the triazine derivative which has an acidic functional group is contained, The two in any one of Claims 1-4 characterized by the above-mentioned. Secondary battery composition.   Furthermore, the composition for secondary batteries in any one of Claims 1-5 containing a solvent (E) and binder resin (F).   The secondary battery composition according to claim 1, further comprising at least one active material (G) selected from the group consisting of a positive electrode active material and a negative electrode active material.   The composition for secondary batteries according to claim 7, wherein the ratio of the average particle diameter of the active material (G) / the dispersed particle diameter (D50) of the carbon material is 2 or more and 100 or less.   A secondary battery electrode having a composite material layer on a current collector, wherein the composite material layer is formed of the composition for secondary battery according to any one of claims 1 to 8. Battery electrode.   A 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, wherein the positive electrode mixture layer or the negative electrode mixture layer A secondary battery comprising: the secondary battery composition according to claim 1.