JP6202395B2 - Dispersant for battery, battery composition using the same, and lithium secondary battery - Google Patents

Description

  The present invention relates to a battery dispersant, a composition and a method for producing the same used for producing an electrode constituting a battery. In particular, the electrode composition of the present invention is suitably used for the production of a lithium secondary battery. Further, the present invention provides a lithium secondary comprising an electrode having excellent discharge characteristics or charge characteristics at a large current, cycle characteristics, and conductivity of the electrode mixture, and having low contact resistance between the electrode current collector and the electrode mixture. It relates to batteries.

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

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

  In general, 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, the carbon material (conducting aid) having excellent conductivity has a large specific surface area and thus has a strong cohesive force, and it is difficult to uniformly mix and disperse it in the slurry for forming an electrode mixture of a lithium secondary battery. 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. Also in this case, if the conductive auxiliary agent is not sufficiently dispersed, the adhesiveness is remarkably reduced. 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 lithium secondary batteries, dispersion of a carbon material that is a conductive additive 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.

  Furthermore, Patent Documents 7 to 10 disclose methods for improving the dispersibility and storage stability of carbon black by using organic dye derivatives or triazine derivatives useful as battery dispersants. However, in recent years, in consideration of the environment and production costs, it has been required to reduce the amount of solvent used and the energy used during drying in dispersion compositions such as various dispersions and paints. In the dispersants disclosed in these patent documents, when the concentration of the dispersion in the dispersion composition is increased, the dispersion composition is thickened and the dispersion particle size is increased to obtain sufficient dispersion stability. It was difficult. In addition, when the electrode mixture is applied to an electrode current collector such as a metal foil, there is a problem in that it is difficult to obtain sufficient battery characteristics due to a decrease in adhesion with a coating film containing these dispersants. It was.

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 International Publication No. WO2008 / 108360 Pamphlet JP 2009-26744 A JP 2010-061932 A JP 2011-162698 A

  In view of the above situation, in the present invention, compared to conventional dispersants, even if the concentration of a dispersion to be typified by a carbon material such as carbon black is high, the viscosity of the dispersion composition and the dispersed particle size are increased. By providing a dispersant for obtaining a dispersion composition having excellent dispersion stability, and improving coating film adhesion for a coating film formed from the electrode-forming composition, It aims at improving the battery performance of the battery produced using this.

  As a result of intensive studies to achieve the above object, the present inventors have found that a dispersion having excellent dispersion stability can be obtained by adding the battery dispersant of the present invention when the conductive additive is dispersed in a solvent. It was found that can be prepared. Furthermore, for the battery composition containing this dispersion, the adhesion between the electrode current collector and the electrode mixture is improved, and the battery performance improvement effect associated therewith has been found, and the present invention has been made. It is.

,
That is, this invention relates to the dispersing agent for batteries shown by following General formula (1).

[一般式（１）中、Ｘ¹は−ＮＨ−または−Ｏ−を表し、Ｙは−Ｘ²−Ｚまたは−（Ｃ_mＨ_2mＯ）_nＨで表される基を表す。Ｘ²は置換基を有してもよいアルキレン基または置換基を有してもよいシクロアルキレン基を表し、Ｚは−ＯＨまたは−ＳＨを表す。ｍは１〜４の整数、ｎは１〜１０の整数を表す。
Ｑ¹およびＱ²はそれぞれ独立に、−Ｏ−Ｒ¹、−Ｓ−Ｒ²、−ＮＨ−Ｒ³、ハロゲン基、置換基を有してもよいアルキル基、置換基を有してもよいアリール基、−Ｘ³−Ｒ⁴または−Ｘ¹−Ｙを表す。
Ｒ¹、Ｒ²およびＲ³はそれぞれ独立に、置換基を有してもよいアルキル基または置換基を有してもよいシクロアルキル基を表す。Ｘ³は−ＮＨ−、−Ｏ−、−Ｓ−、−ＮＨＣＯ−、−ＮＨＳＯ₂−、−ＮＨＣＨ₂ＣＯＮＨＣＨ₂−または−Ｘ⁴−Ｖ−Ｘ⁵−を表す。Ｘ⁴は−ＮＨ−または−Ｏ−を表し、Ｘ⁵は−ＣＯＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ₂−を表す。また、Ｖは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基または置換基を有してもよいアリーレン基を表す。Ｒ⁴は有機色素残基、置換基を有していてもよい複素環基、置換基を有していてもよいアリール基を表す。]

[In General Formula (1), X ¹ represents —NH— or —O—, and Y represents a group represented by —X ² —Z or — (C _m H _2m O) _n H. X ² represents an alkylene group which may have a substituent or a cycloalkylene group which may have a substituent, and Z represents —OH or —SH. m represents an integer of 1 to 4, and n represents an integer of 1 to 10.
Q ¹ and Q ² may each independently have —O—R ¹ , —S—R ² , —NH—R ³ , a halogen group, an alkyl group which may have a substituent, or a substituent. Represents an aryl group, —X ³ —R ⁴ or —X ¹ —Y;
R ¹ , R ² and R ³ each independently represents an alkyl group which may have a substituent or a cycloalkyl group which may have a substituent. X ³ represents —NH—, —O—, —S—, —NHCO—, —NHSO ₂ —, —NHCH ₂ CONHCH ₂ — or —X ⁴ —V—X ⁵ —. X ⁴ represents —NH— or —O—, and X ⁵ represents —CONH—, —NHCO— or —NHSO ₂ —. V represents an alkylene group which may have a substituent or an arylene group which may have a substituent, which is composed of 1 to 20 carbon atoms. R ⁴ represents an organic dye residue, a heterocyclic group which may have a substituent, and an aryl group which may have a substituent. ]

  Moreover, this invention relates to the composition for batteries containing the said dispersing agent for batteries, a solvent, and a conductive support agent.

  The present invention also relates to the above battery composition, further comprising a binder resin and / or an active material.

  In addition, the present invention relates to a method for producing a battery composition in which the battery dispersant and the conductive additive are dispersed in a solvent to obtain a dispersion, and then a binder resin and / or an active material are mixed. .

  Further, the present invention is a lithium secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, One of the said composite material layers is formed by apply | coating the said battery composition on a electrical power collector, It is related with the lithium secondary battery characterized by the above-mentioned.

  According to a preferred embodiment of the present invention, a battery composition having excellent dispersion stability can be obtained without inhibiting the conductivity of the conductive additive. Furthermore, by using the battery composition according to a preferred embodiment of the present invention for an electrode such as a lithium secondary battery, the electrode active material and the conductive additive are uniformly mixed in the electrode mixture, Adhesiveness between the electrode current collector and the electrode mixture can be improved, and the internal resistance of the electrode can be reduced, charging / discharging efficiency can be improved, and battery performance can be improved comprehensively.

  The battery composition of the present invention can be used for lithium secondary batteries, alkaline secondary batteries, nickel cadmium secondary batteries, alkaline manganese batteries, lead batteries, fuel cells, capacitors, etc., but particularly for lithium secondary batteries. It is preferable to use it.

  First, materials contained in the battery dispersant and the battery composition of the present invention will be described.

<Dispersant for battery>
The battery dispersant of the present invention is represented by the following general formula (1).

[一般式（１）中、Ｘ¹は−ＮＨ−または−Ｏ−を表し、Ｙは−Ｘ²−Ｚまたは−（Ｃ_mＨ_2mＯ）_nＨで表される基を表す。Ｘ²は置換基を有してもよいアルキレン基または置換基を有してもよいシクロアルキレン基を表し、Ｚは−ＯＨまたは−ＳＨを表す。ｍは１〜４の整数、ｎは１〜１０の整数を表す。
Ｑ¹およびＱ²はそれぞれ独立に、−Ｏ−Ｒ¹、−Ｓ−Ｒ²、−ＮＨ−Ｒ³、ハロゲン基、置換基を有してもよいアルキル基、置換基を有してもよいアリール基、−Ｘ³−Ｒ⁴または−Ｘ¹−Ｙを表す。
Ｒ¹、Ｒ²およびＲ³はそれぞれ独立に、置換基を有してもよいアルキル基または置換基を有してもよいシクロアルキル基を表す。Ｘ³は−ＮＨ−、−Ｏ−、−Ｓ−、−ＮＨＣＯ−、−ＮＨＳＯ₂−、−ＮＨＣＨ₂ＣＯＮＨＣＨ₂−または−Ｘ⁴−Ｖ−Ｘ⁵−を表す。Ｘ⁴は−ＮＨ−または−Ｏ−を表し、Ｘ⁵は−ＣＯＮＨ−、−ＮＨＣＯ−または−ＮＨＳＯ₂−を表す。また、Ｖは炭素数１〜２０で構成された、置換基を有してもよいアルキレン基または置換基を有してもよいアリーレン基を表す。Ｒ⁴は有機色素残基、置換基を有していてもよい複素環基、置換基を有していてもよいアリール基を表す。]

[In General Formula (1), X ¹ represents —NH— or —O—, and Y represents a group represented by —X ² —Z or — (C _m H _2m O) _n H. X ² represents an alkylene group which may have a substituent or a cycloalkylene group which may have a substituent, and Z represents —OH or —SH. m represents an integer of 1 to 4, and n represents an integer of 1 to 10.
Q ¹ and Q ² may each independently have —O—R ¹ , —S—R ² , —NH—R ³ , a halogen group, an alkyl group which may have a substituent, or a substituent. Represents an aryl group, —X ³ —R ⁴ or —X ¹ —Y;
R ¹ , R ² and R ³ each independently represents an alkyl group which may have a substituent or a cycloalkyl group which may have a substituent. X ³ represents —NH—, —O—, —S—, —NHCO—, —NHSO ₂ —, —NHCH ₂ CONHCH ₂ — or —X ⁴ —V—X ⁵ —. X ⁴ represents —NH— or —O—, and X ⁵ represents —CONH—, —NHCO— or —NHSO ₂ —. V represents an alkylene group which may have a substituent or an arylene group which may have a substituent, which is composed of 1 to 20 carbon atoms. R ⁴ represents an organic dye residue, a heterocyclic group which may have a substituent, and an aryl group which may have a substituent. ]

In the general formula (1), Q ¹ and Q ² may be the same or different. Specific examples thereof include —O—R ¹ , —S—R ² , —NH—R ³ , a halogen group, and a substituent. An alkyl group which may have, an aryl group which may have a substituent, -X ³ -R ⁴ or -X ¹ -Y, and R ¹ , R ² and R ³ are each independently a substituent. And an cycloalkyl group which may have a substituent or a cycloalkyl group which may have a substituent. When Q ¹ and Q ² have a substituent, the substituents may be the same or different. Specific examples thereof include properties such as halogen groups such as fluorine, chlorine and bromine, amino groups, hydroxyl groups and nitro groups. In addition to the group, an alkyl group, an aryl group, a cycloalkyl group, an alkoxyl group, an aryloxy group, an alkylthio group, an arylthio group, and the like can be given. Moreover, there may be a plurality of these substituents.

  As the “alkyl group” of the alkyl group which may have a substituent, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a neopentyl group, an n-hexyl group, Examples include a linear or branched alkyl group such as an n-octyl group, a stearyl group, and a 2-ethylhexyl group. Examples of the “alkyl group having a substituent” include a trichloromethyl group, a trifluoromethyl group, 2,2, 2-trifluoroethyl group, 2,2-dibromoethyl group, 2,2,3,3-tetrafluoropropyl group, 2-ethoxyethyl group, 2-butoxyethyl group, 2-nitropropyl group, benzyl group, 4 -Methylbenzyl group, 4-tert-butylbenzyl group, 4-methoxybenzyl group, 4-nitrobenzyl group, 2,4-dichlorobenzyl group, etc. .

  Examples of the “aryl group” of the aryl group which may have a substituent include a phenyl group, a naphthyl group, and an anthryl group, and the “aryl group having a substituent” includes a p-methylphenyl group, p- Bromophenyl group, p-nitrophenyl group, p-methoxyphenyl group, 2,4-dichlorophenyl group, pentafluorophenyl group, 2-aminophenyl group, 2-methyl-4-chlorophenyl group, 4-hydroxy-1-naphthyl Group, 6-methyl-2-naphthyl group, 4,5,8-trichloro-2-naphthyl group, anthraquinonyl group, 2-aminoanthraquinonyl group and the like.

  Examples of the “cycloalkyl group” of the cycloalkyl group which may have a substituent include a cyclopentyl group, a cyclohexyl group, an adamantyl group and the like, and examples of the “cycloalkyl group having a substituent” include 2,5 -A dimethylcyclopentyl group, 4-tert- butyl cyclohexyl group, etc. are mentioned.

Next, specific examples of X ³ include —NH—, —O—, —S—, —NHCO—, —NHSO ₂ —, —NHCH ₂ CONHCH ₂ — or —X ⁴ —V—X ⁵ —. X ⁴ is —NH— or —O—, and X ⁵ is —CONH—, —NHCO— or —NHSO ₂ —. However, X ³ _{is, -NHCO -, - NHSO 2 -} , - NHCH 2 CONHCH 2 - or -X ⁴ -V-X ⁵ - As represented by the triazine left in the general formula (1) ring and the right The bonding position with R ⁴ is represented. Similarly, when X ⁵ is represented by —CONH—, —NHCO— or —NHSO ₂ —, the left side represents a group V represented by —X ⁴ —V—X ⁵ —, and the right side represents R ⁴ . Represents the bonding position of.

Moreover, as V, the alkylene group which may have a substituent or the arylene group which may have a substituent comprised by C1-C20 is mentioned, The alkylene group which may have a substituent Alternatively, the “substituent” of the arylene group which may have a substituent has the same meaning as the substituents of Q ¹ and Q ² .

The “alkylene group” of the alkylene group which may have a substituent in V is formed by removing one hydrogen atom from the same substituent as the alkyl group described for Q ¹ and Q ² in the general formula (1). Valent groups. Similarly, the “arylene group” of the arylene group which may have a substituent is obtained by removing one hydrogen atom from the same substituent as the aryl group described for Q ¹ and Q ² in the general formula (1). The divalent group which can be mentioned can be mentioned.

Next, specific examples of R ⁴ include an organic dye residue, a heterocyclic group which may have a substituent, and an aryl group which may have a substituent, and an organic dye represented by R ⁴ Examples of the “organic dye” of the residue include diketopyrrolopyrrole dyes, azo dyes such as azo, disazo, polyazo, phthalocyanine dyes, diaminodianthraquinone, anthrapyrimidine, flavantron, anthanthrone, indanthrone, pyranthrone Anthraquinone dyes such as violanthrone, quinacridone dyes, dioxazine dyes, perinone dyes, perylene dyes, thioindigo dyes, isoindoline dyes, isoindolinone dyes, quinophthalone dyes, selenium dyes, metals And complex dyes. In particular, in order to enhance the effect of suppressing the short circuit of the battery due to metal, it is preferable to use an organic dye that is not a metal complex dye, among which an azo dye, anthraquinone dye, metal-free phthalocyanine dye, quinacridone dye, dioxazine Since the pigment | dye is excellent in a dispersibility, it is preferable. More preferred is an azo dye.

Examples of the heterocyclic group which may have a substituent represented by R ⁴ include aromatic or aliphatic heterocycles containing a nitrogen atom, an oxygen atom, a sulfur atom, and a phosphorus atom. Specifically, thienyl group, benzo [b] thienyl group, naphtho [2,3-b] thienyl group, pyrrolyl group, thianthenyl group, furyl group, pyranyl group, isobenzofuranyl group, chromenyl group, xanthenyl group, phenoxy group. Satiynyl group, 2H-pyrrolyl group, imidazolyl group, pyrazolyl group, pyridyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, indolizinyl group, isoindolyl group, 3H-indolyl group, indolyl group, 1H-indazolyl group, purinyl group, 4H-quinolidinyl group, isoquinolyl group, quinolyl group, phthalazinyl group, naphthyridinyl group, quinoxanilyl group Quinazolinyl group, cinnolinyl group, pteridinyl group, 4aH-carbazolyl group, carbazolyl group, β-carbolinyl group, phenanthridinyl group, acridinyl group, perimidinyl group, phenanthrolinyl group, phenazinyl group, phenalsadinyl group, isothiazolyl group, pheno Thiazinyl group, isoxazolyl group, furazanyl group, phenoxazinyl group, isochromanyl group, chromanyl group, pyrrolidinyl group, pyrrolinyl group, imidazolidinyl group, imidazolinyl group, pyrazolidinyl group, pyrazolinyl group, piperidyl group, piperazinyl group, indolinyl group, isoindolinyl group, isoindolinyl group , Morpholinyl group, thioxanthryl group, benzofuryl group, benzothiazolyl group, benzoxazolyl group, benzoimidazolyl group, benzotriazolyl group, etc. And the like. In particular, a heterocyclic group containing at least one of a nitrogen atom and an oxygen atom is preferable because of its excellent dispersibility, and among them, a benzoimidazolyl group is more preferable.

Further, the “aryl group” and the “substituent” in the aryl group which may have a substituent represented by R ⁴ have the same meanings as described for Q ¹ and Q ² , and in particular, from the viewpoint of dispersibility. Therefore, R ⁴ is preferably a phenyl group having a substituent, and more preferably an unsubstituted phenyl group having no substituent.

In the general formula (1), specific examples of Y include a group represented by —X ² —Z or — (C _m H _2m O) _n H, and X ² is an alkylene which may have a substituent. A cycloalkylene group which may have a group or a substituent, Z includes —OH and —SH. M represents an integer of 1 to 4, and n represents an integer of 1 to 10.

The “alkylene group” of the alkylene group which may have a substituent in X ² is formed by removing one hydrogen atom from the same substituent as the alkyl group described for Q ¹ and Q ² in formula (1). A divalent group can be mentioned, and the “cycloalkylene group” of the cycloalkylene group which may have a substituent in X ² is the same as the cycloalkyl group described for Q ¹ and Q ² in formula (1) And a divalent group formed by removing one hydrogen atom from the substituent. In the case of having a substituent, the “substituent” has the same meaning as that of Q ¹ and Q ² above. In particular, from the viewpoint of dispersion stability, X ² is preferably an alkylene group which may have a substituent, and more preferably a linear alkylene group having no substituent.

Specific examples of the structure represented by — (C _m H _2m O) _n H in Y include — (CH ₂ O] _n H, — (CH ₂ CH ₂ O] _n H, — (CH ₂ CH (CH ₃₎ O] _{n H, -. (CH 2} CH 2 CH 2 O ] _n H, and the like, but in these structures and n is an integer from 1 to 10, the n from the viewpoint of dispersibility 1 5 is preferred.

As a combination of R ⁴ and Y, R ⁴ is an azo dye, anthraquinone dye, metal-free phthalocyanine dye, quinacridone dye, dioxazine dye, a heterocyclic group containing at least one of a nitrogen atom and an oxygen atom, It is a phenyl group having a substituent, and X ^{2 of the} group represented by —X ² —Z in Y may be an alkylene group which may have a substituent or — (C _m H _2m O) _n H in Y What combined n whose group n is 1-5 is preferable. Among them, R ⁴ may be an azo dye, a benzoimidazolyl group or an unsubstituted phenyl group having no substituent, and X ^{2 of the} group represented by —X ² —Z in Y may have a substituent. A combination of an alkylene group or a group represented by — (C _m H _2m O) _n H in which Y is 1 to 5 is particularly preferable.

<Conductive aid>
As the conductive aid in the present invention, a carbon material is most preferable. The carbon material is not particularly limited as long as it is a conductive carbon material, but graphite, carbon black, carbon nanotube, carbon nanofiber, carbon fiber, fullerene, etc. alone or in combination of two or more. Can be used. 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 adsorption amount of nitrogen 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 an average of the particle diameters measured with an electron microscope or the like.

  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 Co., Furnace Black), # 2350, # 2400B, # 30050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B, etc. (Manufactured by Chemical Co., Furnace Black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, etc. Fans Black), Ketjen Black EC-300J, EC-600JD (manufactured by Akzo), Denka Black, Denka Black HS-100, FX-35 (manufactured by Denki Kagaku Kogyo Co., Ltd., acetylene black) and the like. Is not to be done.

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

  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-methylpyrrolidone (32.0), hexamethylphosphoric triamide (29.6), dimethyl sulfoxide (48.9), sulfolane (43.3), acetonitrile (37.5), propionitrile (29.7), water (80.1), and the like, but are not limited thereto.

  In particular, the use of a polar solvent having a relative dielectric constant of 15 or more and 200 or less, preferably 15 or more and 100 or less, and more preferably 20 or more and 100 or less is used to obtain good dispersion stability of the carbon material. preferable.

  Solvents with a relative dielectric constant of less than 15 often have a significant decrease in the solubility of the dispersant, and good dispersion cannot be obtained. Is often not obtained.

  In addition, the dispersion stability of the carbon material tended to be influenced by the electron donating property of the solvent. It is preferable to use a solvent having a large electron donating effect. In particular, a solvent having a donor number of 15 kcal / mol or more is preferable, but a solvent having 20 kcal / mol or more and 60 kcal / mol or less is more preferable.

The number of donors is a measure for measuring the electron donating strength of various solvents. As a standard acceptor, 10 ⁻³ M SbCl ₅ in dichloroethane is selected and defined as a reaction molar enthalpy value with a donor. The larger the value, the stronger the electron donating property of the solvent. Also, for some solvents, the donor number is indirectly estimated from the ²³ Na-NMR chemical shift of NaClO _{4 in} the solvent. Regarding the number of donors, V.V. Gutman (translated by Otsuki, Okada), “Donor and Acceptor” (Japan Society of Science Publishing Center, 1983). Depending on the dielectric constant of the solvent, if a solvent having a donor number of less than 15 kcal / mol is used, a sufficient dispersion stabilizing effect may not be obtained. Further, it seems that even if a solvent having a donor number exceeding 60 kcal / mol is used, there is no significant effect of improving the dispersion.

  Examples of the solvent having a donor number of 15 kcal / mol or more include methyl alcohol (donor number: 19), ethyl alcohol (20), ethylamine (55), t-butylamine (57), ethylenediamine (55), pyridine (33. 1), acetone (17), formamide (24), N, N-dimethylformamide (26.6), N, N-diethylformamide (30.9), N, N-dimethylacetamide (27.8), N , N-diethylacetamide (32.2), N-methylpyrrolidone (27.3), hexamethylphosphoric triamide (38.8), dimethyl sulfoxide (29.8), ethyl acetate (17.1) trimethyl phosphate (23 ), Tributyl phosphate (23.7), tetrahydrofuran (20.0), isobutyronitrile (15 4), isopropylidene Ono nitrile (16.1), water (18.0) and the like, without limitation.

  The solvent used is preferably an aprotic polar solvent. An aprotic polar solvent is a polar solvent that does not have the ability to release protons and does not self-dissociate. Aprotic polar solvents do not cause self-association due to hydrogen bonding, and the solvent itself aggregates. The nature is weak. Therefore, the penetration of carbon materials into aggregates is strong, and a dispersion promoting effect is expected. In addition, since the aprotic polar solvent is weak in cohesiveness of the solvent itself, it has a strong dissolving power and can dissolve various dispersants and resins, so that it has excellent versatility.

  In addition to the dispersing agent of the present invention, the carbon material as the conductive auxiliary agent, and the solvent, the solvent is selected in the case where an electrode active material or a binder resin to be described later is further added. In addition to the above effects, the reaction is performed in consideration 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 impact 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 described above, as a solvent satisfying the effect of promoting the dispersion stability of the carbon material, 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. Preference is given to the use of amide aprotic solvents such as N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylpyrrolidone, hexamethylphosphoric triamide.

<Binder resin>
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.

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

<Positive electrode active material and negative electrode active material>
When the composition of the present invention is used for a positive electrode mixture or a negative electrode mixture, at least a positive electrode active material or a negative electrode active material is contained in addition to the dispersant, the carbon material as a conductive additive, and a solvent.

Although it does not specifically limit as a positive electrode active material to be used, A metal compound which can dope or intercalate lithium ion, metal compounds, such as a metal sulfide, a conductive polymer, etc. can be used. Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, 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.

There are no particular limitations on the negative electrode active material to be used, lithium ion doping or capable of intercalating Li metal or its alloy, tin alloy, silicon alloy negative _{electrode, Li x Fe 2 O 3,} Li x Fe 3 O 4 Metal oxides such as Li _x WO ₂ , 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, Alternatively, carbonaceous powders such as natural graphite, carbon black, mesophase carbon black, resin-fired carbon materials, gas-grown carbon fibers, carbon fibers, and the like are used.

<Use of dispersant and composition of the present invention>
The dispersant and composition of the present invention can be used for a positive electrode mixture or a negative electrode mixture. When used for a positive electrode mixture or a negative electrode mixture, a positive / active material in which a positive electrode active material or a negative electrode active material, preferably further containing a binder resin, is added to the composition containing the dispersant, the carbon material as a conductive additive, and a solvent. It is preferable to use it as a negative electrode mixture paste.

  The ratio of the active material to the total solid content in the electrode mixture paste is preferably 80% by weight or more and 98.5% by weight or less. Further, the ratio of the solid content of the battery dispersant of the present invention and the carbon material as the conductive additive in the total solid content in the electrode mixture paste is 0.5% by weight or more and 19% by weight. The following is preferred. The ratio of the binder resin in the total solid content in the electrode mixture paste is preferably 1% by weight or more and 10% by weight or less. The proper viscosity of the electrode mixture paste depends on the method of applying the electrode mixture paste, but generally it is preferably 100 mPa · s or more and 30,000 mPa · s or less.

  The positive / negative electrode composite paste not only has excellent dispersibility of the carbon material particles as a conductive additive, but also has an effect of relaxing aggregation of the positive / negative electrode active material. Because the carbon material particles, which are conductive assistants, have excellent dispersibility, the energy of mixing and dispersing the carbon material as the conductive assistant and the positive and negative electrode active materials in the solvent is the aggregate of the carbon material (conductive assistant). It is believed that the active material can be efficiently transferred to the active material without being obstructed, and as a result, the dispersibility of the positive and negative electrode active materials can be improved.

  In the positive electrode mixture paste, the carbon material particles as the conductive auxiliary agent can be uniformly coordinated and adhered around the positive electrode active material, and excellent conductivity and adhesion can be imparted to the positive electrode mixture layer. Further, since the conductivity is improved, the amount of the carbon material added as a conductive auxiliary agent can be reduced, so that the amount of the positive electrode active material added can be relatively increased, and the capacity which is a large characteristic of the battery can be increased. Can be bigger.

  Furthermore, since the positive electrode mixture paste of the present invention has very little aggregation of the positive electrode active material and the carbon material (conducting aid), a uniform coating film with high smoothness can be obtained when applied to a current collector. The adhesion between the current collector and the positive electrode mixture is improved. In addition, since the dispersing agent acts (for example, adsorbs) on the surface of the carbon material (conductive auxiliary agent), the surface of the positive electrode active material such as the lithium transition metal composite oxide and the surface of the carbon material (conductive auxiliary agent) The action is enhanced and the adhesion between the positive electrode active material and the carbon material (conducting aid) is improved as compared with the case where no dispersant is used.

  In the negative electrode mixture paste, when a carbon material-based active material is used as the negative electrode active material, the aggregation of the carbon material-based active material is alleviated by the effect of the added dispersant. The carbon material particles (conducting aid) can be uniformly coordinated and adhered around the negative electrode active material, and excellent conductivity, adhesion and wettability can be imparted to the negative electrode mixture layer.

  The composition of the present invention can also be used for an electrode underlayer. When used for an electrode underlayer, a dispersion comprising the battery dispersant of the present invention and a carbon material and a solvent as a conductive additive may be used as they are, but the binder resin is added to the electrode underlayer paste. It is preferable to use as. The proportion of the carbon material as a conductive additive in the total solid content of the composition used for the electrode underlayer is preferably 5% by weight or more and 95% by weight or less, more preferably 10% by weight or more and 90% by weight or less. If the carbon material as the conductive auxiliary agent is small, the conductivity of the underlayer may not be maintained. On the other hand, if the carbon material as the conductive auxiliary agent is excessive, the resistance of the coating film may be reduced. In addition, the appropriate viscosity of the electrode base paste depends on the method of applying the electrode base paste, but generally it is preferably 100 mPa · s or more and 30,000 mPa · s or less.

<Production Method of Dispersant and Composition of the Present Invention>
Next, the manufacturing method of the dispersing agent for batteries of this invention is demonstrated.

  The method for producing the dispersant of the present invention is not particularly limited, but is described in, for example, JP-A-60-88185, JP-A-63-305173, JP-A-11-199796, and the like. It can be manufactured with reference to the method described.

  Next, a method for producing the battery composition of the present invention will be described.

  In the above production method, one or more kinds of dispersants selected from battery dispersants are completely or partially dissolved in a solvent, and a carbon material as a conductive assistant is added and mixed in the solution. The dispersant is dispersed in the solvent while acting (for example, adsorbing) on the carbon material. The concentration of the carbon material in the dispersion at this time is preferably 1% by weight or more and 50% by weight or less, although it depends on the characteristic values of the carbon material such as the specific surface area and surface functional group amount of the carbon material used. More preferably, it is 5% by weight or more and 35% by weight or less. If the concentration of the carbon material is too low, the production efficiency is deteriorated. If the concentration of the carbon material is too high, the viscosity of the dispersion is remarkably increased, and the dispersion efficiency, the efficiency of the contamination removal process described later, and the handling of the dispersion are improved. May decrease. In particular, when a step for removing contamination is added, the viscosity of the dispersion at this time is preferably 10,000 mPa · s or less, more preferably 5,000 mPa · s or less, and further preferably 3,000 mPa · s or less.

  The addition amount of the battery dispersant is determined by the specific surface area of the carbon material as the conductive additive used. Generally, the dispersant is 0.5 to 40 parts by weight, preferably 1 to 35 parts by weight, more preferably 2 to 30 parts by weight with respect to 100 parts by weight of the carbon material. Or less. When the amount of the dispersing agent is small, a sufficient dispersing effect cannot be obtained, and an effect of improving wettability to the electrolytic solution and an effect of suppressing metal deposition cannot be obtained sufficiently. Moreover, even if it adds excessively, the remarkable dispersion | distribution improvement effect is not acquired.

  The dispersed particle diameter of the carbon material as the conductive assistant may be reduced to 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 or more and 0.5 μm or less. desirable. It may be difficult to produce a composition having a dispersed particle size of the carbon material as the conductive aid of less than 0.03 μm. In addition, when a composition in which the dispersed particle diameter of the carbon material as the conductive auxiliary agent exceeds 2 μm is used, the additive amount of the conductive auxiliary agent must be increased in order to reduce the resistance distribution of the electrode and reduce the resistance. There may be a problem such as disappearing. The dispersed particle size referred to here is a particle size (D50) that is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. A particle size distribution meter such as a dynamic light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.).

  Further, as a device for dispersing the carbon material in the solvent while causing the dispersant to act on the carbon material (for example, adsorption), a disperser usually 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, a disperser in which the agitator and vessel are made of a ceramic or resin disperser, or the metal agitator and vessel surface are treated with tungsten carbide spraying or resin coating. Is preferably used. 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.

  In addition, it is preferable to include a step of removing contaminants such as metal foreign matters when dispersing the carbon material. Carbon materials such as carbon black, graphite, and carbon fiber often contain metallic foreign matters derived from their manufacturing processes (as line contamination and catalysts). This is very important to prevent short circuit. In the present invention, due to the effect of the battery dispersant, the agglomeration of the carbon material is well loosened, and the viscosity of the dispersion becomes low. Therefore, the concentration of the carbon material in the dispersion is lower than when no dispersant is added. Even when it is high, the metallic foreign matter can be efficiently removed. Examples of methods for removing metallic foreign substances include iron removal with a magnet, filtration, and centrifugation.

  Examples of the method for adding the binder resin include a method in which a solid binder resin is added and dissolved while stirring a dispersion obtained by dispersing a carbon material as a conductive additive in a solvent in the presence of the dispersant. . Moreover, what melt | dissolved binder resin in the solvent is produced previously, and the method of mixing with the said dispersion is mentioned. Further, after adding the binder resin to the dispersion, the dispersion treatment may be performed again by the dispersion apparatus.

  In addition, when the carbon material as the conductive additive is dispersed in the solvent in the presence of the battery dispersant of the present invention, a part or all of the binder resin can be added simultaneously to perform the dispersion treatment.

  As a method for adding the positive electrode active material or the negative electrode active material, the positive electrode active material or the negative electrode active material is added while stirring the dispersion obtained by dispersing the carbon material as the conductive additive in the solvent in the presence of the above-described dispersant. And a dispersion method. In addition, when the carbon material as a conductive additive is dispersed in a solvent in the presence of the battery dispersant of the present invention, a part or all of the positive electrode active material or the negative electrode active material is simultaneously added to perform a dispersion treatment. You can also. Moreover, as an apparatus for performing mixing and dispersion at this time, the above-described dispersers used for ordinary pigment dispersion and the like can be used.

  As described above, the battery composition of the present invention is usually produced, distributed, and used as a dispersion (liquid) containing a solvent, a paste, and 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 prepared by a liquid phase method may be considered as a dry powder by once removing the solvent for reasons such as transportation cost. And it is also considered that this dry powder is redispersed with an appropriate solvent and used for forming an electrode mixture layer. Therefore, the composition of the present invention is not limited to a liquid dispersion, and may be a composition in a dry powder state.

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

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

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

  Examples of the method for forming the electrode base layer on the current collector include a method of applying the electrode base paste described above to the electrode current collector and drying. The film thickness of the electrode underlayer is not particularly limited as long as the conductivity and adhesion are maintained, but is generally 0.05 μm or more and 20 μm or less, preferably 0.1 μm or more and 10 μm or less. It is.

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

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

<Electrolyte>
As the electrolytic solution constituting the lithium secondary battery of the present invention, an electrolyte containing lithium is dissolved in a non-aqueous solvent. As 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, LiBPh _{4 and the} like, but are not limited thereto.

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

  Furthermore, the electrolyte solution may be a polymer electrolyte that is held in a polymer matrix and made into 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, a polysiloxane having a polyalkylene oxide segment, and the like.

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

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example, unless the summary is exceeded. In addition, in order to clarify the difference between individual compositions, a dispersion composition comprising a dispersant, a carbon material, and a solvent is referred to as a “carbon material dispersion”, a dispersion composition comprising a dispersant, a carbon material, a solvent, and a binder resin. Is referred to as a “composite paste”. The battery dispersion composition comprising a “carbon material dispersion varnish”, a dispersant, a carbon material, a solvent, a binder resin, and an active material. Unless otherwise specified, N-methyl-2-pyrrolidone used as a solvent is abbreviated as “NMP”, and mass% is abbreviated as “%”.

<Dispersant>
The structures of the battery dispersants (a) to (w) represented by the general formula (1) of the present invention are shown below. Moreover, the structure of the dispersing agent (A)-(D) mentioned as a comparative example is shown.

<Method for producing dispersant>
A battery dispersant represented by the general formula (1) of the present invention was produced by the method described in the following examples. In the examples, “parts” means “parts by weight”, and the dispersant of the present invention was obtained using a MALDI mass spectrometer autoflex III (hereinafter referred to as TOF-MS) manufactured by Bruker Daltonics. The molecular ion peak of the obtained mass spectrum was identified with the coincidence of the mass number obtained by calculation.

[Example 1]
(Production of Dispersant (a))
In a reaction vessel, 1500 parts of water was cooled to 10 ° C., and 18.4 parts of cyanuric chloride was added and stirred. To this, 26.3 parts of 2- (2-aminoethoxy) ethanol was added and reacted at 10 ° C. for 3 hours. Subsequently, sodium carbonate was gradually added to the reaction solution to adjust the pH to 7.0 to 8.0, and the temperature was raised to 40 ° C., followed by stirring for 1 hour. Next, the reaction solution was cooled to room temperature, 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or less, and the product was filtered and washed with water. The obtained filtration residue was added to 1500 parts of water and stirred. Further, 29.8 parts of 5-aminobenzimidazolone and 80.0 parts of 25% caustic soda were added, and the temperature was raised to 90 ° C. After stirring at 90 ° C. for 3 hours, the mixture was cooled to room temperature, and 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or less. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 39.1 parts of dispersant (a). As a result of mass spectrometry by TOF-MS, it was confirmed that the structure of the dispersant (a) was obtained.

[Example 2]
(Production of dispersant (b))
Dispersant (b) was obtained in the same manner except that 15.3 parts of 2-aminoethanol was used instead of 2- (2-aminoethoxy) ethanol in the production of dispersant (a). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (b) was confirmed.

[Example 3]
(Production of dispersant (c))
In a reaction vessel, 18.4 parts of cyanuric chloride was added to 400 parts of acetone and dissolved. To this, 28.2 parts of hexaethylene glycol and 10.1 parts of triethylamine were added and heated to reflux for 5 hours. Subsequently, 44.7 parts of 5-aminobenzimidazolone and 50.6 parts of triethylamine were added to the reaction solution, and the mixture was further heated under reflux for 12 hours. After cooling to room temperature, 1000 parts of water was added, and subsequently 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or lower. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 31.9 parts of dispersant (c). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (c) was confirmed.

[Example 4]
(Production of dispersant (d))
In a reaction vessel, 1500 parts of water was cooled to 10 ° C., and 18.4 parts of cyanuric chloride was added and stirred. To this, 8.9 parts of 4-amino-1-butanol was added and reacted at 10 ° C. for 3 hours. Subsequently, 44.7 parts of 5-aminobenzimidazolone was added to the reaction solution, and the temperature was raised to 40 ° C., followed by stirring for 2 hours. Next, 80.0 parts of 25% caustic soda was added and the temperature was raised to 90 ° C., followed by stirring for 3 hours. After cooling to room temperature and gradually adding 30% hydrochloric acid to adjust the pH to 3.0 or lower, the product is filtered and washed with water, and the resulting residue is dried under reduced pressure to give 42.1 parts of a dispersant. (D) was obtained. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (d) was confirmed.

[Example 5]
(Production of dispersant (e))
In a reaction vessel, 1500 parts of water was cooled to 10 ° C., and 18.4 parts of cyanuric chloride was added and stirred. To this, 15.0 parts of p-aminoacetanilide was added and reacted at 10 ° C. for 3 hours. Subsequently, 22.5 parts of 2-amino-1-propanol was added to the reaction solution, and the mixture was heated to 40 ° C. and stirred for 2 hours. Next, 80.0 parts of 25% caustic soda was added and the temperature was raised to 90 ° C., followed by stirring for 3 hours. The reaction solution was cooled to room temperature, 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or less, and the product was filtered and washed with water. The obtained filtration residue was added to 250 parts of water and stirred, and 110.0 parts of 30% hydrochloric acid was further added, and the temperature was raised to 100 ° C. After stirring at 100 ° C. for 3 hours, the mixture was cooled to 5 ° C., and 6.9 parts of sodium nitrite dissolved in 45 parts of water was added and stirred for 1 hour. Subsequently, sulfamic acid was added to eliminate excess sodium nitrite, and this was used as a diazonium salt aqueous solution. Meanwhile, 23.3 parts of 5-acetoacetylaminobenzimidazolone was added to 1350 parts of water, and 30.8 parts of 25% caustic soda and 96.9 parts of sodium carbonate were added and stirred for 30 minutes to form a coupler solution. . The 5 ° C. diazonium salt aqueous solution was poured into this coupler solution over 30 minutes to carry out a coupling reaction. At this time, it was confirmed that the pH was 9.0 or more, and after stirring at room temperature for 2 hours, the pH was adjusted to 9.0 or more by adding sodium carbonate, heated to 80 ° C. and stirred for 1 hour. . Then, after cooling to room temperature and adjusting the pH to 3.0 or less by adding 30% hydrochloric acid, the product was filtered and washed with water, and the resulting residue was dried under reduced pressure to give 50.8 parts. Dispersant (e) was obtained. As a result of mass spectrometry by TOF-MS, it was confirmed that the structure of the dispersant (e) was obtained.

[Example 6]
(Production of dispersant (f))
In the production of the dispersant (a), 18.8 parts of 3-amino-1-propanol was used instead of 2- (2-aminoethoxy) ethanol, and 18.6 parts of aniline was used instead of 5-aminobenzimidazolone. A dispersant (f) was obtained in the same manner except that. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (f) was confirmed.

[Example 7]
(Production of dispersant (g))
Dispersant (g) was obtained in the same manner except that 31.5 parts of 2- (2-aminoethoxy) ethanol was used instead of 2-amino-1-propanol in the production of dispersant (e). . As a result of mass spectrometry by TOF-MS, it was confirmed that the structure of the dispersant (g) was obtained.
[Example 8]
(Production of dispersant (h))
Dispersant (h) was obtained in the same manner except that 18.6 parts of aniline was used instead of 5-aminobenzimidazolone in the production of dispersant (a). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (h) was confirmed.

[Example 9]
(Production of dispersant (i))
In the production of the dispersant (d), 10.5 parts of 2- (2-aminoethoxy) ethanol are used instead of 4-amino-1-butanol, and 27.9 parts of aniline are used instead of 5-aminobenzimidazolone. A dispersant (i) was obtained in the same manner except that. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (i) was confirmed.

[Example 10]
(Production of dispersant (j))
In the production of the dispersant (d), 10.3 parts of 4-amino-2-methyl-1-butanol instead of 4-amino-1-butanol, and 27.9 parts of aniline instead of 5-aminobenzimidazolone A dispersant (j) was obtained in the same manner except that was used. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (j) was confirmed.

[Example 11]
(Production of dispersant (k))
In the production of the dispersant (c), 17.4 parts of 4-methoxy-1-naphthol is used instead of hexaethylene glycol, and 26.7 parts of 2-amino-1-butanol is used instead of 5-aminobenzimidazolone. A dispersant (k) was obtained in the same manner except that. As a result of mass spectrometry by TOF-MS, it was confirmed that the structure of the dispersant (k) was obtained.

[Example 12]
(Production of dispersant (l))
In the production of the dispersant (c), except that 42.5 parts of heptapropylene glycol was used instead of hexaethylene glycol and 14.5 parts of 4-chlorobenzenethiol was used instead of 5-aminobenzimidazolone. Dispersant (l) was obtained. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (l) was confirmed.

[Example 13]
(Production of dispersant (m))
In the production of the dispersant (e), 18.3 parts of 2-aminoethanol instead of 2-amino-1-propanol, and 26.3 of 3-hydroxy-2-naphthanilide instead of 5-acetoacetylaminobenzimidazolone A dispersant (m) was obtained in the same manner except that the parts were used. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (m) was confirmed.

[Example 14]
(Production of dispersant (n))
In the production of the dispersant (a), 15.3 parts of 2-aminoethanol was used instead of 2- (2-aminoethoxy) ethanol, and 21.4 parts of benzylamine was used instead of 5-aminobenzimidazolone. Obtained a dispersing agent (n) in the same manner. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (n) was confirmed.

[Example 15]
(Production of dispersant (o))
In a reaction vessel, 400 parts of 1,2-dimethoxyethane was cooled to 5 ° C., and 18.4 parts of cyanuric chloride was added and dissolved. To this, 283.3 parts of phenylmagnesium bromide (16% tetrahydrofuran solution) was added dropwise over 1 hour and reacted at 5 ° C. for 3 hours. Subsequently, the reaction solution was gradually warmed and heated to reflux for 5 hours. After cooling to room temperature, the product was filtered and washed with 1,2-dimethoxyethane. The obtained filtration residue was added to 1500 parts of water and stirred, and 17.8 parts of 4-amino-1-butanol and 80.0 parts of 25% caustic soda were added, and the temperature was raised to 90 ° C. After stirring at 90 ° C. for 3 hours, the mixture was cooled to room temperature, and 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or less. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 25.6 parts of dispersant (o). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (o) was confirmed.

[Example 16]
(Production of dispersant (p))
In a reaction vessel, 18.4 parts of cyanuric chloride was added to 400 parts of methyl ethyl ketone and dissolved. To this, 48.6 parts of tetraethylene glycol and 30.3 parts of triethylamine were added and heated to reflux for 10 hours. Subsequently, 48.4 parts of 3-amino-4-methoxybenzanilide and 30.3 parts of triethylamine were added to the reaction solution, and the mixture was further heated to reflux for 5 hours. After cooling to room temperature, 1000 parts of water was added, and subsequently 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or lower. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 60.0 parts of dispersant (p). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (p) was confirmed.

[Example 17]
(Production of dispersant (q))
In a reaction vessel, 1500 parts of water was cooled to 10 ° C., and 18.4 parts of cyanuric chloride was added and stirred. To this, 13.0 parts of N- (4-aminobutyl) acetamide was added and reacted at 10 ° C. for 3 hours. Subsequently, 30.9 parts of 4-amino-2-methyl-1-butanol was added to the reaction solution, heated to 40 ° C., and stirred for 2 hours. Next, 80.0 parts of 25% caustic soda was added and the temperature was raised to 90 ° C., followed by stirring for 3 hours. The reaction solution was cooled to room temperature, 30% hydrochloric acid was gradually added to adjust the pH to 3.0 or less, and the product was filtered and washed with water. The obtained filtration residue was added to 250 parts of water and stirred, and 110.0 parts of 30% hydrochloric acid was further added, and the temperature was raised to 100 ° C. After stirring at 100 ° C. for 3 hours, the reaction solution cooled to room temperature was adjusted to pH 7.0 to 8.0 with sodium carbonate, and this was used as an intermediate solution. On the other hand, 48.5 parts of thionyl chloride was added to a solution obtained by dissolving 31.2 parts of quinacridone in 250 parts of chlorosulfonic acid in a reaction vessel, and reacted at 60 ° C. for 3 hours. Subsequently, the reaction solution was poured into 5000 parts of cold water at 3 ° C., the precipitate was filtered and washed with water, and the obtained residue was added to the intermediate solution. Further, 10.1 parts of triethylamine was added and reacted at 40 ° C. for 3 hours. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 61.7 parts of dispersant (q). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (q) was confirmed.

[Example 18]
(Production of dispersant (r))
In a reaction vessel, 400 parts of methanol was cooled to 5 ° C., and 19.1 parts of 1- (o-tolyl) biguanide was added and stirred. To this was added 28.4 parts of ethyl trifluoroacetate and allowed to react at 40 ° C. for 5 hours. After cooling to room temperature, the product was filtered and washed with methanol, and the resulting filter residue was added to 500 parts of water and stirred. Subsequently, 7.5 parts of paraformaldehyde was added, and sodium carbonate was gradually added to adjust the pH to 9.0 to 10.0. Subsequently, after heating up to 40 degreeC, it stirred for 2 hours, the product was filtered and washed with water, and the obtained residue was dried under reduced pressure, and 23.9 parts of dispersing agent (r) was obtained. As a result of mass spectrometry by TOF-MS, it was confirmed that the structure of the dispersant (r) was obtained.

[Example 19]
(Production of dispersant (s))
In a reaction vessel, 300 parts of acetone was cooled to 10 ° C., and 12.6 parts of melamine was added and stirred. To this, 44.5 parts of isonicotinoyl chloride hydrochloride and 30.3 parts of triethylamine were added and reacted at 50 ° C. for 4 hours. Next, the product was filtered, washed with acetone, the obtained filtration residue was added to 500 parts of water, and the mixture was stirred. Subsequently, 7.5 parts of paraformaldehyde was added, and sodium carbonate was gradually added to adjust the pH to 9.0 to 10.0. After heating up to 40 degreeC, it stirred for 2 hours, the product was filtered and washed with water, the obtained residue was dried under reduced pressure, and 33.3 parts of dispersing agent (s) was obtained. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (s) was confirmed.

[Example 20]
(Production of dispersant (t))
In a reaction vessel, 18.4 parts of cyanuric chloride was added to 400 parts of methyl ethyl ketone and dissolved. To this, 15.1 parts of p-acetamidophenol and 30.3 parts of triethylamine were added and heated to reflux for 3 hours. Next, 7.3 parts of sec-butylamine was added to the reaction solution and reacted at 40 ° C. for 2 hours. Subsequently, 15.4 parts of 2-aminoethanethiol and 20.2 parts of triethylamine were further added and reacted at 80 ° C. for 3 hours. Subsequently, after cooling to room temperature, the product was filtered and washed with water, and the resulting filter residue was added to 250 parts of water and stirred. Further, 110.0 parts of 30% hydrochloric acid was added, the temperature was raised to 100 ° C., stirred for 3 hours, and then cooled to room temperature. The pH of the reaction solution was adjusted to 7.0 to 8.0 with sodium carbonate, 35.5 parts of 3-pyridinesulfonyl chloride and 20.2 parts of triethylamine were added, and the reaction was performed at 40 ° C. for 2 hours. Then, it cooled to room temperature, the product was filtered and washed with water, and the obtained residue was dried under reduced pressure to obtain 41.4 parts of a dispersant (t). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (t) was confirmed.

[Example 21]
(Production of dispersant (u))
In the production of the dispersant (t), 11.6 parts of cyclohexanethiol instead of p-acetamidophenol, 15.0 parts of p-aminoacetanilide instead of sec-butylamine, and 4-amino instead of 2-aminoethanethiol Dispersant (u) was obtained in the same manner except that 23.0 parts of cyclohexanol and 54.1 parts of anthraquinone-2-carbonyl chloride were used instead of 3-pyridinesulfonyl chloride. As a result of mass spectrometry by TOF-MS, the structure of the dispersant (u) was confirmed.

[Example 22]
(Production of dispersant (v))
In a reaction vessel, 300 parts of acetone was cooled to 10 ° C., and 12.6 parts of melamine was added and stirred. To this, 28.6 parts of p-toluenesulfonyl chloride and 15.1 parts of triethylamine were added and reacted at 10 ° C. for 3 hours. Subsequently, the product was filtered and washed with water, and the obtained filtration residue was added to 500 parts of water and stirred. Subsequently, 15.0 parts of paraformaldehyde was added, and sodium carbonate was gradually added to adjust the pH to 9.0 to 10.0. After raising the temperature to 40 ° C., the mixture was stirred for 2 hours, the product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 30.6 parts of a dispersant (v). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (v) was confirmed.

[Example 23]
(Production of dispersant (w))
In a reaction vessel, 18.4 parts of cyanuric chloride was added to 400 parts of acetone and dissolved. To this, 10.4 parts of 3-ethoxy-1-propanol and 20.2 parts of triethylamine were added and heated to reflux for 3 hours. Subsequently, 11.5 parts of 4-aminocyclohexanol and 20.2 parts of triethylamine were added to the reaction solution, and further reacted at 40 ° C. for 2 hours. After cooling to room temperature, 1000 parts of water and 60.7 parts of 28% aqueous ammonia were added and stirred at 80 ° C. for 4 hours. Next, the product was filtered and washed with water, and the obtained filtration residue was added to 500 parts of water and stirred to obtain an intermediate solution. On the other hand, 18.7 parts of 2-chloroacetamide and 7.5 parts of paraformaldehyde were added to 170 parts of concentrated sulfuric acid in a reaction vessel, and 20.8 parts of anthraquinone was further added to the dissolved solution. Reacted for hours. Subsequently, the reaction solution was poured into 3400 parts of cold water at 3 ° C., the precipitate was filtered and washed with water, and the obtained residue was added to the intermediate solution. Further, 10.1 parts of triethylamine was added and reacted at 40 ° C. for 3 hours. The product was filtered and washed with water, and the resulting residue was dried under reduced pressure to obtain 48.3 parts of dispersant (w). As a result of mass spectrometry by TOF-MS, the structure of the dispersant (w) was confirmed.

<Production and evaluation of carbon material dispersion>
Carbon material dispersions were produced by the methods described in the following examples and comparative examples, and the dispersion stability was evaluated by measuring the viscosity and the dispersed particle size.

  For the production of the carbon material dispersion, the dispersants (a) to (w) described in Examples 1 to 23, N-methyl-2-pyrrolidone, and the following carbon materials were used. Further, as comparative examples, dispersants (A) to (D) (described in Patent Document 7, Patent Document 8, and Patent Document 9) were used.

# 30 (Mitsubishi Chemical Co., Ltd.): Furnace black, the average primary particle diameter determined by observation with an electron microscope is 30 nm, and the specific surface area determined by the S-BET formula from the nitrogen adsorption amount is 74 m ² / g.
Monarch 800 (manufactured by Cabot): Furnace black, average primary particle diameter determined by observation with an electron microscope of 17 nm, specific surface area determined by S-BET formula from nitrogen adsorption amount is 210 m ² / g, hereinafter referred to as “M800” Abbreviated.
Denka black granular product (manufactured by Denki Kagaku Kogyo Co., Ltd.): acetylene black, the average primary particle diameter determined by observation with an electron microscope is 35 nm, the specific surface area determined by the S-BET formula from the amount of nitrogen adsorption is 68 m ² / g or less Abbreviated as “granular product”.
EC-300J (manufactured by Akzo): Ketjen black, the average primary particle diameter determined by observation with an electron microscope is 40 nm, and the specific surface area determined by the S-BET formula from the amount of nitrogen adsorbed is 800 m ² / g.
Carbon nanotubes: multi-walled carbon nanotubes, fiber diameters of 10 to 20 nm and fiber lengths of 2 to 5 μm determined by observation with an electron microscope, hereinafter abbreviated as CNT.
VGCF (manufactured by Showa Denko KK): carbon nanofiber, fiber diameter 150 nm, fiber length 10-20 μm determined by observation with an electron microscope.

  The viscosity of the carbon material dispersion was measured at 25 ° C. and 60 rpm using a B-type viscometer (“BL” manufactured by Toki Sangyo Co., Ltd.). The dispersion particle size of various carbon blacks was measured using a dynamic light scattering type particle size distribution meter (“MICROTRACK UPA” manufactured by Nikkiso Co., Ltd.) using N-methyl-2-pyrrolidone as a diluent solvent at the time of measurement. The average particle size (D50 value) was taken as the dispersed particle size. The degree of dispersion of the carbon nanotube and the carbon nanofiber dispersion was determined by determination with a grind gauge (according to JIS K5600-2-5).

[Examples 24 to 49]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and each dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed with a paint conditioner for 2 hours using zirconia beads as a medium. Dispersions D-1 to D-26 were obtained. All of them had a low viscosity, a small dispersed particle size, and good dispersion stability.

[Example 50 to Example 51]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and each dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed with a paint conditioner for 2 hours using zirconia beads as a medium. Dispersions D-27 to D-28 were obtained. In both cases, the degree of dispersion measured with a low viscosity and 50 μm grind gauge was 10 μm in both Example 50 and Example 51, and the dispersion stability was good.

[Comparative Examples 1 to 7]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and a dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed using a zirconia bead as a medium with a paint conditioner for 2 hours. Liquids D-29 to D-35 were obtained. However, all of the carbon material dispersions were highly viscous and remarkably aggregated, and the dispersed particle size was large.

[Comparative Examples 8 to 9]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and a dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed using a zirconia bead as a medium with a paint conditioner for 2 hours. Liquids D-36 to D-37 were obtained. However, all the carbon material dispersions were highly viscous and remarkably agglomerated, and the degree of dispersion measured with a 100 μm grind gauge showed many coarse particles of 100 μm or more in both Comparative Example 8 and Comparative Example 9.

[Comparative Examples 10 to 16]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and a dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed using a zirconia bead as a medium with a paint conditioner for 2 hours. Liquids D-38 to D-44 were obtained. All had low viscosity and small dispersion particle size and good dispersion stability. However, the carbon material content was 10%, and when these dispersants were used, the carbon material content was 20%. It was not possible to obtain a high-concentration carbon material dispersion liquid. When trying to obtain a high-concentration carbon material dispersion having a carbon material content of 20%, as shown in Comparative Examples 1 to 7, the viscosity becomes high, the dispersion particle size is large, and a stable dispersion is obtained. Couldn't get.

[Comparative Examples 17 to 18]
In accordance with the composition shown in Table 1, N-methyl-2-pyrrolidone and a dispersant were charged into a glass bottle, mixed and dissolved, then each carbon material was added, and dispersed using a zirconia bead as a medium with a paint conditioner for 2 hours. Liquids D-45 to D-46 were obtained. All of them had low viscosity and good dispersion stability, but the carbon material content was 10%. When these dispersants were used, a high-concentration carbon material having a carbon material content of 20%. A dispersion could not be obtained. When trying to obtain a high-concentration carbon material dispersion with a carbon material content of 20%, as shown in Comparative Example 8 and Comparative Example 9, the viscosity became high and a stable dispersion could not be obtained. .

<Production and evaluation of carbon material dispersion varnish>
Carbon material-dispersed varnishes were produced by the methods described in the following examples and comparative examples, and the dispersion stability was evaluated by measuring the viscosity and the dispersed particle size.

  For the production of the carbon material-dispersed varnish, the carbon material dispersions D-1 to D-46 described in Examples 24 to 51 and Comparative Examples 1 to 18, N-methyl-2-pyrrolidone, and the following The binder resin was used.

  KF polymer W1100 (manufactured by Kureha): polyvinylidene fluoride (PVDF), hereinafter abbreviated as PVDF.

  The viscosity, dispersed particle size, and degree of dispersion of the carbon material dispersion varnish were measured by the same method as that for the carbon material dispersion.

[Examples 52 to 77]
According to the composition shown in Table 2, the carbon material dispersions D-1 to D-26 prepared in Examples 24 to 49, the binder resin, and N-methyl-2-pyrrolidone were mixed with a disper to disperse the carbon material. Varnishes V-1 to V-26 were obtained. All of them had a low viscosity, a small dispersed particle size, and good dispersion stability.

[Examples 78 to 79]
In accordance with the composition shown in Table 2, the carbon material dispersion prepared in Examples 50 to 51, binder resins D-27 to D-28, and N-methyl-2-pyrrolidone were mixed with a disper to obtain a carbon material dispersion varnish. V-27 to V-28 were obtained. In both Examples 78 and 79, the degree of dispersion measured with a low viscosity and 50 μm grind gauge was 10 μm, and the dispersion stability was good.

[Comparative Examples 19 to 25]
In accordance with the composition shown in Table 2, the carbon material dispersions D-29 to D-35 prepared in Comparative Examples 1 to 7 were mixed with a binder resin and N-methyl-2-pyrrolidone with a disper to obtain a carbon material dispersion varnish. V-29 to V-35 were obtained. However, all of the carbon material-dispersed varnishes were highly agglomerated with high viscosity, and the dispersed particle size was large.

[Comparative Example 26 to Comparative Example 27]
In accordance with the composition shown in Table 2, the carbon material dispersions D-36 to D-37 prepared in Comparative Examples 8 to 9 were mixed with a binder resin and N-methyl-2-pyrrolidone with a disper to obtain a carbon material dispersion varnish. V-36 to V-37 were obtained. However, all of the carbon material-dispersed varnishes were highly agglomerated with high viscosity, and many coarse particles of 100 μm or more were observed with a 100 μm grind gauge.

[Comparative Example 28 to Comparative Example 34]
In accordance with the composition shown in Table 2, the carbon material dispersions D-38 to D-44 prepared in Comparative Examples 10 to 16 were mixed with a binder resin and N-methyl-2-pyrrolidone with a disper to obtain a carbon material dispersion varnish. V-38 to V-44 were obtained. Both had a low viscosity and a small dispersed particle size and good dispersion stability, but the content of the carbon material contained in the dispersion varnish was 5%, and when these dispersants were used, It was not possible to obtain a high-concentration carbon material dispersion having a carbon material content of 10%. When trying to obtain a high-concentration carbon material dispersion having a carbon material content of 10%, as shown in Comparative Examples 19 to 25, the viscosity becomes high, the dispersion particle size is large, and a stable dispersion is obtained. Couldn't get.

[Comparative Example 35 to Comparative Example 36]
In accordance with the composition shown in Table 2, the carbon material dispersions D-45 to D-46 prepared in Comparative Examples 17 to 18 were mixed with a binder resin and N-methyl-2-pyrrolidone with a disper to obtain a carbon material dispersion varnish. V-45 to V-46 were obtained. All of them had low viscosity and good dispersion stability, but the content of the carbon material contained in the dispersion varnish was 5%, and when these dispersants were used, the carbon material content was 10%. It was not possible to obtain a high-concentration carbon material dispersion liquid. When trying to obtain a high-concentration carbon material dispersion having a carbon material content of 10%, as shown in Comparative Example 26 and Comparative Example 27, the viscosity increased, and a stable dispersion could not be obtained. .

<Production of compound paste>
For the production of the composite paste, the carbon material-dispersed varnish prepared in Examples 52 to Example 79 and Comparative Examples 19 to 27, N-methyl-2-pyrrolidone, PVDF as a binder resin, and the following The active material was used.

HLC-22 (Honjo Chemical Co., Ltd.): Positive electrode active material, lithium cobaltate (LiCoO ₂ ), average primary particle size determined by observation with an electron microscope was 6.6 μm, determined from the amount of nitrogen adsorption by the S-BET equation Specific surface area is 0.62 m ² / g, hereinafter abbreviated as LCO.

[Example 80 to Example 107]
According to the composition shown in Table 3, the carbon material-dispersed varnishes V-1 to V-28 prepared in Examples 52 to 79 and the active material, PVDF, N-methyl-2-pyrrolidone were kneaded with a planetary mixer. Material pastes P-1 to P-28 were obtained.

[Comparative Example 37 to Comparative Example 45]
In accordance with the composition shown in Table 3, the carbon material dispersion varnishes V-29 to V-37 prepared in Comparative Examples 19 to 27 and the active material, PVDF, N-methyl-2-pyrrolidone were kneaded with a planetary mixer. Material pastes P-29 to P-37 were obtained.

<Assembly and evaluation of lithium ion secondary battery positive electrode evaluation cell>
Next, this composite paste was applied onto an aluminum foil having a thickness of 20 μm serving as a current collector using a doctor blade, followed by drying under reduced pressure to adjust the thickness of the electrode to 100 μm. Furthermore, the rolling process by a roll press was performed, the positive electrode from which thickness becomes 85 micrometers was produced, and the adhesiveness was evaluated with the following method.

Using the knife, the incision from the surface of the electrode to the depth reaching the current collector was cut into 6 grids in the vertical and horizontal directions at intervals of 2 mm. Adhesive tape was applied to the cut and immediately peeled off, and the degree of the active material falling off was determined by visual judgment (Tables 4 and 5). The evaluation criteria are shown below.
A: “No peeling (practical problem-free level)”
○: “Slightly peeled off (problem but usable level)”
Δ: “About half peel”
×: “Peeling at most parts”

Subsequently, a separator made of a porous polypropylene film between the working electrode and the counter electrode (manufactured by Celgard Co., Ltd. #) was prepared by punching out the electrode produced above to a diameter of 9 mm and using a metal lithium foil (thickness 0.15 mm) as a counter electrode. 2400) is inserted and laminated and filled with an electrolyte (nonaqueous electrolyte in which LiPF ₆ is dissolved at a concentration of 1M in a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a mass ratio of 1: 1) to fill a bipolar sealed metal A cell (HS flat cell manufactured by Hosen Co., Ltd.) was assembled. The cell was assembled in a glove box substituted with argon gas.

The produced battery evaluation cell was fully charged at a constant current and constant voltage charge (upper limit voltage 4.2 V) at a room temperature (25 ° C.) with a charge rate of 0.2 C and 1.0 C, and at a constant current at the same rate as during charging Charge / discharge for discharging to a discharge lower limit voltage of 3.0V is defined as one cycle (charge / discharge interval rest time 30 minutes). (Tables 4 and 5).

  From Tables 4 and 5, in Examples 80 to 107 using the battery composition of the present invention, compared with Comparative Examples 37 to 45, the adhesion of the coating film was improved, the initial discharge capacity, and Good results were also observed in the discharge capacity retention rate after 200 cycles.

Claims (5)

A battery dispersant represented by the following general formula (1).

[In General Formula (1), X ¹ represents —NH— or —O—, and Y represents a group represented by —X ² —Z or — (C _m H _2m O) _n H. X ² represents an alkylene group which may have a substituent or a cycloalkylene group which may have a substituent, and Z represents —OH or —SH. m represents an integer of 1 to 4, and n represents an integer of 1 to 10.
Q ¹ and Q ² may each independently have —O—R ¹ , —S—R ² , —NH—R ³ , a halogen group, an alkyl group which may have a substituent, or a substituent. Represents an aryl group, —X ³ —R ⁴ or —X ¹ —Y;
R ¹ , R ² and R ³ each independently represents an alkyl group which may have a substituent or a cycloalkyl group which may have a substituent. X ³ represents —NH—, —O—, —S—, —NHCO—, —NHSO ₂ —, —NHCH ₂ CONHCH ₂ — or —X ⁴ —V—X ⁵ —. X ⁴ represents —NH— or —O—, and X ⁵ represents —CONH—, —NHCO— or —NHSO ₂ —. V represents an alkylene group which may have a substituent or an arylene group which may have a substituent, which is composed of 1 to 20 carbon atoms. R ⁴ represents an organic dye residue, a heterocyclic group which may have a substituent, and an aryl group which may have a substituent. ] The battery composition containing the dispersing agent for batteries of Claim 1, a solvent, and a conductive support agent. The battery composition according to claim 2, further comprising a binder resin and / or an active material. A method for producing a battery composition, comprising dispersing the battery dispersant according to claim 1 and a conductive additive in a solvent to obtain a dispersion, and then mixing a binder resin and / or an active material. A lithium secondary battery comprising: a positive electrode having a positive electrode mixture layer on a current collector; a negative electrode having a negative electrode mixture layer on the current collector; and an electrolyte containing lithium. A lithium secondary battery comprising: a battery composition according to claim 2 or 3 applied on a current collector.