WO2019009242A1

WO2019009242A1 - Binder composition, electrode mix, electrode, non-aqueous electrolyte secondary battery, and dispersant

Info

Publication number: WO2019009242A1
Application number: PCT/JP2018/025054
Authority: WO
Inventors: 佳余子岡田; 正太小林; 達宮崎; 卓村田; 泰輔小関
Original assignee: 株式会社クレハ
Priority date: 2017-07-05
Filing date: 2018-07-02
Publication date: 2019-01-10
Also published as: JP2019016489A

Abstract

Provided is a binder composition which has a reduced viscosity while keeping the bonding performance thereof during the production of an electrode. A binder composition which can be used for bonding an electrode active material to a current collector, and is characterized by containing an adhesive resin and a dispersant, wherein the dispersant is a compound represented by formula (I) or (II).

Description

Binder composition, electrode mixture, electrode, non-aqueous electrolyte secondary battery, and dispersant

The present invention relates to a binder composition, an electrode mixture, an electrode, and a non-aqueous electrolyte secondary battery, and a dispersant. More specifically, the present invention relates to a binder composition, an electrode mixture using the binder composition, an electrode and a non-aqueous electrolyte secondary battery, and a dispersant used in the binder composition.

In recent years, the development of electronic technology has been remarkable, and small-sized portable devices are becoming more sophisticated. Therefore, miniaturization and weight reduction, that is, higher energy density, are required for power supplies used for these. Nonaqueous electrolyte secondary batteries represented by lithium ion secondary batteries and the like are widely used as batteries having high energy density. In addition, it has also been proposed to use a non-aqueous electrolyte secondary battery as a power source for hybrid cars, electric cars and the like, and its practical use has been started.

In an electrode for a non-aqueous electrolyte secondary battery, a resin composition called a binder is used to bind an electrode active material to a current collector. The electrode is manufactured by applying a slurry-like electrode mixture in which the binder and the electrode active material are mixed to a current collector and drying it.

While it is desired to further increase the energy density of the secondary battery, a binder having high adhesion performance that can reduce the compounding amount as much as possible is desired so that the compounding amount of the active material can be increased.

As a means to improve the adhesiveness of a binder, the method of using polyvinylidene fluoride for binder resin is known, for example, and various things are proposed also as polyvinylidene fluoride. For example, copolymerizing a vinylidene fluoride copolymer having an intrinsic viscosity of more than 2.0 dl / g (see, for example, Patent Document 1), a vinylidene fluoride and a monoester of an unsaturated dibasic acid such as maleic acid monomethyl ester. And a vinylidene fluoride copolymer (see, for example, Patent Document 3) obtained by copolymerizing vinylidene fluoride and an acrylic acid compound. Proposed.

Japanese Patent Publication "Japanese Patent Application Laid-Open No. 9-289023 (disclosed on November 4, 1997)" Japanese Patent Publication "Japanese Patent Application Laid-Open No. 6-172452 (published on June 21, 1994)" Japanese Patent Publication "Tokukai 2010-525124 (July 22, 2010 published)"

However, there is a problem that the electrode mixture using the binder as described above has a high viscosity.

When the viscosity of the electrode mixture is high, aggregates are likely to be formed at the time of electrode production, and the aggregates may lower the performance of the battery. In addition, when the viscosity of the electrode mixture is high, there is a problem that the workability at the time of electrode production is poor and the productivity is poor.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a binder composition capable of reducing the viscosity of an electrode mixture while having high adhesion performance.

In order to solve the above-mentioned subject, the binder composition concerning one mode of the present invention is a binder composition used in order to bind an electrode active material to a current collection object, and adhesive resin and a dispersing agent are used. And the dispersant is a compound represented by the following formula (I) or (II):

In formula (I), X ⁶ independently represents a hydrogen atom or a methyl group, X ¹ represents a methylene group, N—X ² or O, and X ² and X ³ independently represent H, —NH ₂ , A hydrocarbon group having 1 to 8 carbon atoms,-(A ¹ O) ₁ R ¹ (wherein A ¹ is an alkylene group having 2 to 4 carbon atoms, 1 is an integer of 1 to 5 and R ¹ is H or carbon Or an alkyl group of 1 to 8) or -A ² NX ⁴ X ⁵ (wherein A ² is an alkylene group of 1 to 4 carbon atoms, X ⁴ and X ⁵ are independently H or 1 to 4 carbon atoms) Represents a hydrocarbon group of

In the formula (II), m is an integer of 1 to 50, A ³ is an alkylene group having 2 to 4 carbon atoms, R ² and R ³ are each independently H, an alkyl group having 1 to 18 carbon atoms or 1 carbon atom Represents an aminoalkyl group of -18.

Further, the dispersant according to one aspect of the present invention is a dispersant for being added to a binder composition used to bind an electrode active material to a current collector, and the binder composition has an adhesive property. It is a binder composition containing resin, and is a dispersing agent which contains a compound represented by the following formula (I) or (II) as a main component.

According to one aspect of the present invention, it is possible to provide a binder composition capable of reducing the viscosity of the electrode mixture when it is used as an electrode mixture while having high adhesion performance.

Hereinafter, an embodiment of the present invention will be described in detail. Here, in the present specification, unless otherwise specified, an electrode mixture layer formed of an electrode mixture using the binder composition of the present embodiment is formed on a current collector, unless otherwise specified. Mean an electrode of a non-aqueous electrolyte secondary battery. Moreover, the "battery" in this specification means the nonaqueous electrolyte secondary battery provided with the "electrode."

[Binder composition]
The binder composition which concerns on this embodiment is used in order to bind an electrode active material to a collector in the electrode in which the electrode mixture layer containing an electrode active material is formed on a collector. . The binder composition contains an adhesive resin and a dispersant. The binder composition may contain a solvent in addition to the adhesive resin and the dispersant. The binder composition may further contain a conductive aid. The binder composition may further contain an additive as an optional component.

(Adhesive resin)
The adhesive resin contained in the binder composition according to this embodiment is not particularly limited as long as the electrode active material can be bound to the current collector, and a vinylidene fluoride resin, an acrylic resin, and a synthetic rubber Etc. can be used.

In the present specification, a vinylidene fluoride-based resin is a resin containing a constituent unit derived from vinylidene fluoride as a main component, and a homopolymer of vinylidene fluoride and a monomer copolymerizable with vinylidene fluoride Both copolymers with vinylidene fluoride are included. "Containing a constitutional unit derived from vinylidene fluoride as a main component" is intended to mean that the constitutional unit derived from vinylidene fluoride in the polymer exceeds 50% by mole. Preferably, the constituent unit derived from vinylidene fluoride is 90 mol% or more, more preferably 95 mol% or more. Other monomer components copolymerizable with vinylidene fluoride include hydrocarbon monomers such as ethylene and propylene; trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropyrene, vinyl fluoride, and perfluoro Monomers containing fluorine other than vinylidene fluoride such as perfluoroalkyl vinyl ether represented by methyl vinyl ether; unsaturated dibasic acids such as maleic acid and citraconic acid or monoalkyl esters thereof; and (meth) acrylic acid Examples thereof include alkyl (meth) acrylate compounds represented by methyl (meth) acrylate. Also, acryloyloxyethyl succinic acid, methacryloyloxyethyl succinic acid, acryloyloxy propyl succinic acid, methacryloyloxy propyl succinic acid, acryloyloxy ethyl phthalic acid, methacryloyloxy ethyl phthalic acid, 2-carboxyethyl acrylate, And 2-carboxyethyl methacrylate may be used.

An acrylic resin is a resin containing a structural unit of (meth) acrylic acid, (meth) acrylic acid ester, or (meth) acrylonitrile as a main component, and poly (meth) acrylic acid or poly (meth) acrylic acid Methyl, poly (meth) acrylonitrile, polyacrylamide, copolymers of (meth) acrylic acid and (meth) acrylonitrile, and copolymers of (meth) acrylic acid ester and (meth) acrylonitrile, etc. are mentioned, among them , Polyacrylic acid or polyacrylonitrile is preferred.

Examples of synthetic rubbers include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, (meth) acrylic acid ester-butadiene rubber, butadiene rubber, chloroprene rubber, isoprene rubber, peptyl rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, fluorine Examples thereof include rubber, acrylic rubber, urethane rubber, polysulfide rubber, chlorinated butyl rubber, and shrimp chlorohydrin rubber. Among these, styrene-butadiene rubber (SBR) is preferable. These synthetic rubbers are preferably in the form of a water dispersible latex or emulsion in order to facilitate preparation of the mixture, and thickeners may be mixed and used.

As thickeners, cellulose compounds such as carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose, ammonium salts or alkali metal salts of the cellulose compounds, poly (meth) acrylic acid and modified poly (meth) acrylics Polycarboxylic acids such as acids, alkali metal salts of the polycarboxylic acids, polyvinyl alcohols, modified polyvinyl alcohols and polyvinyl alcohol (co) polymers such as ethylene-vinyl alcohol copolymers, (meth) acrylic acid, maleic acid and Examples thereof include unsaturated carboxylic acids such as fumaric acid and water-soluble polymers such as cationized guar gum. Among them, carboxymethyl cellulose and its salts are preferable.

Among them, a vinylidene fluoride resin is preferable as the adhesive resin.

The content of the adhesive resin is preferably 10 to 99.7 parts by mass, more preferably 15 to 99 parts by mass, and still more preferably 20 to 98 parts by mass with respect to 100 parts by mass of the binder composition. is there. In the binder composition, the total amount of the adhesive resin, the dispersant and the additive is 100 parts by mass.

(Dispersant)
The dispersant contained in the binder composition according to the present embodiment is a compound represented by the following formula (I) or a compound represented by the following formula (II).

In the formula (I), a plurality of X ⁶ each independently represent a hydrogen atom or a methyl group, X ¹ represents a methylene group, N—X ² or O, and X ² and X ³ independently represent H , -NH ₂ , a hydrocarbon group having 1 to 8 carbon atoms,-(A ¹ O) ₁ R ¹ or -A ² NX ⁴ X ⁵ .

The hydrocarbon group having 1 to 8 carbon atoms at X ² and X ³ is preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group having 1 to 8 carbon atoms is preferably an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and 3 to 8 carbon atoms. And a cycloalkenyl group of Examples of the alkyl group include linear alkyl groups such as methyl group, ethyl group and n-butyl group, and branched alkyl groups such as isopropyl group, isobutyl group and tert-butyl group. Among the alkyl groups, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and a methyl group or an ethyl group is more preferable. Among these, as the alkenyl group, an alkenyl group having 2 to 6 carbon atoms is preferable, and alkenyl having 2 to 4 carbon atoms is more preferable. Among them, a cycloalkyl group having 3 to 6 carbon atoms is preferable, a cycloalkyl group having 5 or 6 carbon atoms is more preferable, and a cyclohexyl group is more preferable. Among them, a cycloalkenyl group having 3 to 6 carbon atoms is preferable, a cycloalkenyl group having 5 or 6 carbon atoms is more preferable, and a cyclohexenyl group is more preferable. Among them, as the hydrocarbon group having 1 to 8 carbon atoms in X ² and X ³ , an aliphatic hydrocarbon group having 1 to 6 carbon atoms is preferable, and a methyl group, an ethyl group and a cyclohexenyl group are more preferable.

^{_{^{- (A 1 O) l R}}} A 1 in ¹ represents an alkylene group having 2 to 4 carbon atoms, preferably an ethylene group. l is an integer of 1 to 5, preferably an integer of 1 to 4, and more preferably an integer of 1 or 2. - ^(A _{¹ O)} ^R ₁ in the l ^{R 1} is H or an alkyl group having 1 to 8 carbon atoms, preferably H or an alkyl group having 1 to 4 carbon atoms, more preferably H or a carbon number 1 Or an alkyl group of 2.

^{A 2} in -A ² NX ⁴ X ⁵ represents an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 1 or 2 carbon atoms. ^{X 4} and ^{X 5} in -A ² NX ⁴ X ⁵ independently represent H or a hydrocarbon group having 1 to 4 carbon atoms. Preferred as -A ¹ NX ⁴ X ⁵ is an aminoethyl group (-C ₂ H ₄ NH ₂ ).

In formula (II), m is an integer of 1 to 50, A ³ represents an alkylene group having 2 to 4 carbon atoms, R ² and R ³ independently represent H, an alkyl group having 1 to 18 carbon atoms Or an aminoalkyl group having 1 to 18 carbon atoms.

M in the formula (II) is preferably 1 to 20, more preferably 1 to 6, still more preferably 1 to 4, and particularly preferably 1 or 2.

The alkylene group having 2 to 4 carbon atoms in A ³ is preferably an ethylene group.

The alkyl group having 1 to 18 carbon atoms in R ² and R ³ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and still more preferably a methyl group or It is an ethyl group.

The aminoalkyl group having 1 to 18 carbon atoms in R ² and R ³ is preferably an aminoalkyl group having 1 to 6 carbon atoms, more preferably an aminoalkyl group having 1 to 4 carbon atoms, and still more preferably It is an aminomethyl group or an aminoethyl group.

Among the compounds represented by the formula (I), X ¹ is NH or O, X ³ is H, —NH ₂ , a hydrocarbon group having 1 to 6 carbon atoms, —C ₂ H ₄ OH or — Compounds which are C ₂ H ₄ NH ₂ are preferred.

As a compound represented by Formula (II), the compound whose R < ² > and R < ³ > is H, a methyl group, an ethyl group, or an aminoethyl group independently is preferable.

Among the compounds represented by the formula (I), particularly preferred compounds as dispersants are morpholine, 4-methylmorpholine, 4-ethylmorpholine, 4- (2-hydroxyethyl) morpholine, 4- (1-cyclohexenyl) morpholine 4- (2-aminoethyl) morpholine, 4-aminomorpholine, piperazine, 1-methylpiperazine, N- (2-aminoethyl) piperazine, and 1- (2-hydroxyethyl) piperazine.

Among the compounds represented by the formula (II), particularly preferred compounds as dispersants are monoethanolamine, N-methylethanolamine, N-ethylethanolamine and 2- (2-aminoethylamino) ethanol.

In the binder composition, only one type of dispersant may be used, or a plurality of dispersants may be mixed and used.

The content of the dispersant is preferably 0.1 to 80 parts by mass, more preferably 0.2 to 70 parts by mass, and still more preferably 0.3 to 80 parts by mass with respect to 100 parts by mass of the binder composition. 60 parts by mass. In the binder composition, the total amount of the adhesive resin, the dispersant and the additive is 100 parts by mass.

Moreover, as another aspect of a dispersing agent, the form of the composition which contains the compound represented by Formula (I) or the compound represented by Formula (II) as a main component may also be sufficient.

In addition, when the additive represented by Formula (III) shown next is included in a binder composition, the compound represented by Formula (I) or the compound represented by Formula (II) as a main component is included. The dispersant as a composition may be an embodiment in which the additive represented by Formula (III) is contained.

(Additive)
The binder composition according to the present embodiment can contain additives in addition to the adhesive resin and the dispersant described above. The additive is a compound represented by the following formula (III).

R ⁴ -O- (A ⁴ O) _n -R ⁵ (III)
In the formula (III), n is an integer of 1 to 100, R ⁴ is a hydrocarbon group having 1 to 18 carbon atoms, R ⁵ is H or an alkyl group having 1 to 4 carbon atoms, and A ⁴ is 2 to 4 carbon atoms It is an alkylene group.

From the viewpoint of improving the dispersibility of the adhesive resin, n is preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 4. By using a compound in which n is 1 to 4, the dispersibility of the adhesive resin can be further improved. On the other hand, n may be 1 to 100, preferably 1 to 50, and more preferably 1 to 12, from the viewpoint of the peel strength of the adhesive mixture layer finally obtained. It is more preferable that it is ̃3. By using a compound in which n is 1 to 100, the peel strength of the finally obtained adhesive mixture layer can be improved.

R ⁴ is preferably a phenyl group or an alkyl group having 1 to 18 carbon atoms. The alkyl group is more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms.

R ⁵ is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group and an ethyl group.

Specifically, A ⁴ is an ethylene group, a propylene group or a butylene group, preferably an ethylene group or a propylene group, more preferably a propylene group.

Preferred as the compound represented by the formula (III) from the viewpoint of improving the dispersibility of the adhesive resin, R ⁴ and R ⁵ are independently an alkyl group having 1 to 4 carbon atoms, and A ⁴ is an ethylene group or It is a compound which is a propylene group.

When the binder composition contains an additive, the content of the additive is preferably 1 to 80 parts by mass, and more preferably 3 to 70 parts by mass with respect to 100 parts by mass of the binder composition. . In the binder composition, the total amount of the adhesive resin, the dispersant and the additive is 100 parts by mass.

(Solvent for binder composition)
The binder composition may contain a solvent. The solvent used for the binder composition may be a non-aqueous solvent or water as long as it can dissolve or disperse the binder composition. As the non-aqueous solvent, for example, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethylurea, Triethyl phosphate, trimethyl phosphate, acetone, methyl ethyl ketone, cyclohexanone and the like can be mentioned. These solvents may be used alone or in combination of two or more.

When the adhesive resin of the binder composition according to the embodiment is a vinylidene fluoride resin, the inherent viscosity is not particularly limited, but is preferably 1 dl / g or more and 5 dl / g or less, and 1.5 dl / g. It is more preferably g or more and 4 dl / g or less, and still more preferably 1.7 dl / g or more and 3.5 dl / g or less. When the inherent viscosity is 1 dl / g or more, the adhesion of the binder composition becomes better. Moreover, when the inherent viscosity is 5 dl / g or less, the decrease in the slurry solid content is further suppressed, and the productivity is further improved.

(Method of producing binder composition)
In the present embodiment, the binder composition may be prepared, for example, by mixing an adhesive resin, a dispersant, a conductive auxiliary agent, an additive, a solvent, and the like by an existing method so as to be a uniform binder composition. The order of mixing is not particularly limited. For example, a dispersant may be directly added to the adhesive resin, or the adhesive resin and the dispersant may be mixed. A method of mixing a solution in which an adhesive resin is dissolved or dispersed in a solvent and a dispersing agent, a method of mixing a solution in which an adhesive resin is dissolved or dispersed in a solvent and a solution in which a dispersing agent is dissolved The adhesive resin or the solution thereof may be mixed with the dispersing agent or the solution thereof, respectively, in the production of

The binder composition according to the present embodiment can obtain low shear viscosity, that is, high dispersibility, by including the above-described dispersant. Thereby, it can suppress that an aggregate produces on an electrode surface by forming an electrode using electrode mixture containing a binder constituent concerning this embodiment. Therefore, in the battery finally obtained, it is possible to suppress the deterioration of the battery performance due to the aggregates.

[Electrode mix]
The electrode mixture in the present embodiment contains a binder composition and an electrode active material. The electrode mixture may further contain a solvent. An electrode can be manufactured by apply | coating this electrode mixture on a collector and forming an electrode mixture layer. The electrode mixture is in the form of slurry and can be adjusted to a desired viscosity by adjusting the amount of solvent.

The electrode mixture can be made into an electrode mixture for a positive electrode or an electrode mixture for a negative electrode by changing the type of the electrode active material or the like according to the type of the current collector to be coated.

(Solvent for electrode mixture)
The solvent used in the electrode mixture in the present embodiment is not particularly limited as long as it can dissolve or disperse the binder composition described above, and may be a non-aqueous solvent, or water It may be As the non-aqueous solvent, for example, N-methyl-2-pyrrolidone (NMP), dimethylformamide, N, N-dimethylacetamide, N, N-dimethylsulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate Trimethyl phosphate, acetone, methyl ethyl ketone, tetrahydrofuran and the like. These solvents may be used alone or as a mixed solvent of two or more kinds. When a non-aqueous solvent is used in the electrode mixture, nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide and N, N-dimethylacetamide are preferable, and N-methyl- More preferred is 2-pyrrolidone (NMP).

The content of the solvent is preferably 15 to 300 parts by mass, and 20 to 250 parts by mass, based on 100 parts by mass of the binder composition, the electrode active material, and the other components in the electrode mixture. It is more preferable that Within the range of the amount of the solvent mentioned above, the solution viscosity becomes appropriate and the handling property is excellent.

(Electrode active material)
The electrode active material used in the electrode mixture according to the present embodiment is, as described above, the electrode active material for the negative electrode, ie, the negative electrode, when the electrode mixture according to the present embodiment is used as the electrode mixture for the negative electrode. An active material may be used, and when the electrode mixture according to the present embodiment is used as an electrode mixture for a positive electrode, an electrode active material for a positive electrode, that is, a positive electrode active material may be used.

As a positive electrode active material, the lithium type positive electrode active material containing lithium is mentioned, for example. Examples of lithium-based positive electrode active materials include complex metal chalcogen compounds represented by the general formula LiMY ₂ such as LiCoO ₂ and LiCo _x Ni _{1 -x} O ₂ (0 ≦ x <1), or complex metal oxides, LiMn ₂ O composite metal oxides taking a spinel structure such as ₄ and LiFePO ₄ olivine-type lithium compounds such like. Here, M is at least one of transition metals such as Co, Ni, Fe, Mn, Cr and V, and Y is a chalcogen element such as O and S.

As the negative electrode active material, conventionally known materials including carbon-based materials such as graphite can be used.

(Conduction agent)
The electrode mixture in this embodiment may further contain a conductive aid. A conductive additive is added for the purpose of improving the conductivity of the electrode mixture layer when using an olivine-type lithium compound such as LiFePO ₄ or an active material having a small electron conductivity such as LiCoO ₂ as an electrode active material It is. As the conductive additive, for example, carbon black materials such as carbon black, carbon nanotubes, graphite fine powder and graphite fiber, and metal fine powder or metal fiber such as nickel and aluminum can be used.

The conductive aid may be contained in the binder composition as described above, in addition to being contained in the electrode mixture. The same materials as described above can also be used when included in the binder composition.

(Other components of electrode mixture)
The electrode mixture in this embodiment may contain other components other than the components described above. Examples of other components include pigment dispersants such as polyvinyl pyrrolidone and the like.

(Method of producing electrode mixture)
The method for producing the electrode mixture according to this embodiment may be, for example, mixing the binder composition, the electrode active material, the solvent, and the conductive auxiliary agent so as to form a uniform slurry, and the order of mixing is particularly limited I will not. For example, the electrode active material may be added directly to the binder composition, or alternatively, the electrode active material may first be added to a solvent, and a mixture obtained by stirring and mixing may be added to the binder composition. Furthermore, when the binder composition contains a solvent, an electrode active material or the like may be added before the solvent is added to the adhesive resin. In addition, an electrode active material or the like may be added to the adhesive resin or the solution or the dispersant or the solution thereof.

〔electrode〕
The electrode in the non-aqueous electrolyte secondary battery in the present embodiment is formed by providing an electrode mixture layer formed of the above-mentioned electrode mixture on a current collector. The electrode mixture layer may be formed on at least one surface of the current collector, and may be formed on both surfaces of the current collector.

(Current collector)
As a current collector used for the electrode in the present embodiment, a current collector generally used in the technical field can be used. Examples of the current collector for the negative electrode include copper and the like, and examples of the current collector for the positive electrode include aluminum and the like. Moreover, as a shape of a collector, metal foil, a metal mesh, etc. are mentioned. However, the present invention is not limited to these, and the type and shape may be appropriately selected according to the application and the like.

(Electrode mixture layer)
The electrode mixture layer is a layer obtained by applying the electrode mixture described above to a current collector and drying it. There is no particular limitation on the method of applying the electrode mixture, and a known method such as a bar coater, a die coater, or a comma coater can be used.

The thickness of the electrode mixture layer is not particularly limited, but is usually 20 to 250 μm, and preferably 20 to 150 μm. The weight per unit area of the electrode mixture layer is not particularly limited, but is usually 20 to 700 g / m ² and preferably 30 to 500 g / m ² .

The drying temperature and drying time for forming the electrode mixture layer are usually 1 to 300 minutes at a temperature of 50 to 150 ° C. Moreover, the pressure at the time of drying is not particularly limited, but the drying is usually performed under atmospheric pressure or reduced pressure.

Further, a pressing process may be further performed, and when the pressing process is performed, the pressure is usually 1 to 200 MPa-G.

Since the electrode in the present embodiment is formed using an electrode mixture having a low shear viscosity, ie, high dispersibility, containing the binder composition according to the present embodiment, it is an electrode with less aggregates. Therefore, by using the electrode in this embodiment, it is possible to suppress the decrease in the performance of the battery due to the aggregates. Since the electrode in the present embodiment is formed using the electrode mixture containing the binder composition according to the present embodiment, high adhesion between the electrode mixture layer and the current collector, that is, high peel strength is obtained. Can. By this, peeling of the electrode mixture layer from the current collector can be suppressed, and deterioration of the performance of the battery due to peeling of the electrode mixture layer can be suppressed.

Non-aqueous electrolyte secondary battery
The non-aqueous electrolyte secondary battery in the present embodiment includes the above-described electrode. The non-aqueous electrolyte secondary battery according to the present embodiment also includes, for example, a polymer battery containing a gel electrolyte. It does not specifically limit about the other member (for example, separator) in a non-aqueous electrolyte secondary battery, For example, the member used conventionally can be used.

Since the non-aqueous electrolyte secondary battery in the present embodiment includes the electrode formed of the electrode mixture containing the binder composition according to the present embodiment, the decrease in battery performance is suppressed.
[Summary]

As apparent from the above, the present invention includes the following.

A binder composition used to bind an electrode active material to a current collector, comprising: an adhesive resin and a dispersant, wherein the dispersant is a compound represented by the following formula (I) or (II) It is a composition.

In the compound represented by the above formula (I), X ¹ is NH or O, X ³ is H, -NH ₂ , a hydrocarbon group having 1 to 6 carbon atoms, -C ₂ H ₄ OH or- it is preferably a compound which is a C _₂ H ₄ NH _2.

The compound represented by the above formula (II) is a compound wherein R ² and R ³ are independently H, or an alkyl group having 1 to 2 carbon atoms or an aminoalkyl group, and m is 1 or 2. Is preferred.

In addition, the above dispersants are morpholine, 4-methylmorpholine, 4-ethylmorpholine, 4- (2-hydroxyethyl) morpholine, 4- (1-cyclohexenyl) morpholine, 4- (2-aminoethyl) morpholine, 4 -Aminomorpholine, piperazine, 1-methylpiperazine, N- (2-aminoethyl) piperazine, 1- (2-hydroxyethyl) piperazine, monoethanolamine, N-methylethanolamine, N-ethylethanolamine, and 2- Preferably, it is at least one selected from the group consisting of (2-aminoethylamino) ethanol.

Moreover, it is preferable that the above-mentioned binder composition further contains the additive represented by following formula (III).

R ⁴ -O- (A ⁴ O) _n -R ⁵ (III)
(In the formula (III), n is an integer of 1 to 100, R ⁴ is a hydrocarbon group having 1 to 18 carbon atoms, R ⁵ is H or an alkyl group having 1 to 4 carbon atoms, and A ⁴ is 2 to 4 carbon atoms Is an alkylene group of
In one embodiment, the additive is a compound in which n is 1 to 4 and A ⁴ is an ethylene group or a propylene group.

In one aspect, the additive is preferably ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, dipropylene glycol dimethyl ether or diethylene glycol diethyl ether.

The adhesive resin is preferably a vinylidene fluoride resin, an acrylic resin, or a synthetic rubber.

The adhesive resin is preferably polyvinylidene fluoride, polyacrylic acid, polyacrylonitrile, or styrene butadiene rubber.

Moreover, the electrode mixture which concerns on 1 aspect of this invention contains the above-mentioned binder composition and an electrode active material.

In the electrode according to one aspect of the present invention, a mixture layer formed of the above-mentioned electrode mixture is provided on a current collector.

A non-aqueous electrolyte secondary battery according to an aspect of the present invention includes the above-described electrode.

Examples will be shown below, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it is needless to say that various aspects are possible as to details. Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the disclosed technical means are also included. It is included in the technical scope of the invention. Also, all of the documents described in the present specification are incorporated by reference.

An electrode mixture was prepared as described below, and the dispersion properties were evaluated and the shear viscosity was measured. Moreover, the electrode was produced using electrode mixture agent, electrode property evaluation and peeling strength test were done.

Example 1-1
(Preparation of electrode mixture)
LiFePO ₄ (manufactured by Takasen Co., Ltd.), conductive carbon black (manufactured by TIMCAL, SUPER C65), and vinylidene fluoride copolymer (manufactured by Kureha, KF) as an adhesive resin so as to obtain the composition shown in Table 1 below. Polymer # 9700, inherent viscosity 2.5 dl / g) was dispersed in N-methyl-2-pyrrolidone (NMP), and morpholine was added as a dispersing agent to obtain an electrode mixture.

(Evaluation of dispersion properties)
The dispersion properties of the obtained electrode mixture were visually evaluated based on the following criteria. Note that ◎ is the best, and x is the worst. The results of the dispersion property evaluation are shown in Table 3.

<Evaluation criteria for evaluation of dispersion properties by visual observation>
:: There was almost no undispersed mass, and it was possible to suck with a syringe ○: A viscous liquid with a slight amount of undispersed mass which can not be absorbed by the dropper Δ: There was undispersed mass ×: Very undispersed mass (Shear viscosity measurement)
The shear viscosity (mPa · s) of the obtained electrode mixture was measured using a viscoelastic device (“MCR101” manufactured by Anton Paar Co., Ltd.) under the conditions of 0.1 rpm → 200 rpm → 0.1 rpm. The results are shown in Table 3.

(Fabrication of electrode)
The obtained electrode mixture was coated on a 15 μm thick Al foil with a bar coater and dried at 130 ° C. for 30 minutes to produce a single-sided coated electrode having a single-sided basis weight of 200 g / m ² .

(Evaluation of electrode properties)
The electrode properties of the electrodes obtained as described above were visually evaluated based on the following criteria. Note that ◎ is the best, and x is the worst. The results are shown in Table 3.

<Evaluation of electrode characteristics by visual observation>
:: no aggregates or streaks ○: slight aggregates or streaks Δ: aggregates or streaks ×: very much agglomerates or streaks (peel strength test)
The obtained electrode is cut out into a length of 50 mm and a width of 20 mm, and a 90 degree peel test at a head speed of 30 mm / min using a tensile tester ("LTS-5010N" manufactured by Minebea Mitsumi Corporation) according to JIS K6854-1. And the peel strength (gf / mm) was measured. The results are shown in Table 3.

Example 1-2
The same procedure as in Example 1-1 was repeated, except that the dispersant was changed to 4-methylmorpholine.

Example 1-3
The same procedure as in Example 1-1 was repeated, except that 4-ethylmorpholine was used as the dispersant.

Example 1-4
The same procedure as in Example 1-1 was repeated, except that the dispersing agent was changed to 4- (2-hydroxyethyl) morpholine.

Example 1-5
The same procedure as in Example 1-1 was repeated, except that the dispersant was changed to 4- (2-aminoethyl) morpholine.

[Example 1-6]
The same procedure as in Example 1-1 was repeated, except that the dispersant was changed to 4-aminomorpholine.

Example 1-7
The same procedure as in Example 1-1 was repeated except that piperazine was used as the dispersant.

[Example 1-8]
The same procedure as in Example 1-1 was repeated, except that 1-methylpiperazine was used as the dispersant.

[Example 1-9]
The same procedure as in Example 1-1 was repeated, except that the dispersant was N- (2-aminoethyl) piperazine.

Example 1-10
The same procedure was performed as in Example 1-1 except that 2- (methylamino) ethanol was used as the dispersant.

Example 1-11
The same procedure was performed as in Example 1-1 except that 2- (ethylamino) ethanol was used as the dispersant.

Example 1-12
The same procedure as in Example 1-1 was repeated, except that the dispersant was monoethanolamine.

Example 2
The same procedure as in Example 1-1 was repeated except that the adhesive resin was changed to a vinylidene fluoride copolymer (Kureha, KF polymer # 9400, inherent viscosity 2.1 dl / g).

[Example 3]
The same procedure as in Example 1-1 was repeated, except that the adhesive resin was changed to vinylidene fluoride homopolymer (Kureha, KF polymer # 7300, inherent viscosity: 3.1 dl / g).

Example 4
The same procedure as in Example 1-1 was repeated except that the adhesive resin was changed to polyacrylonitrile (manufactured by Sigma-Aldrich).

[Example 5]
The same procedure as in Example 1-1 was repeated except that the adhesive resin was changed to polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.).

[Example 6]
Natural Graphite (BTR, BTR 918), Conductive Carbon Black (TIMCAL, SUPER C65), and Styrene Butadiene Rubber (Nippon Zeon, BM-400B) as an adhesive resin so as to obtain the composition shown in Table 2 below. A resin obtained by condensation of the following with a ratio of 2: 1 in molar ratio and carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 4H) is dispersed in ultrapure water, and morpholine is added as a dispersing agent to obtain an electrode mixture. The

[Example 7]
The same procedure as in Example 6 was performed except that the adhesive resin was polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and the solvent was NMP. Dispersion property evaluation, preparation of an electrode and shear viscosity measurement were performed in the same manner as in Example 6. The results are shown in Table 4.

Example 8-1
(Preparation of electrode mixture)
The same procedure as in Example 1-1 was carried out except that 0.5 parts by mass of ethylene glycol dimethyl ether (hereinafter, additive 1) was further added as an additive. The results of the dispersion property evaluation and the shear viscosity measurement are shown in Table 5.

(Frequency dispersion measurement)
About the obtained electrode mixture, distortion dispersion measurement was performed using the viscoelastic apparatus ("MCR101" by anton pearl company), and distortion value was calculated | required. Frequency dispersion measurement was performed with the determined strain value to determine loss tangent (loss modulus / storage modulus). The evaluation of the dispersibility by the difference of loss tangent was performed. The results are shown in Table 5.

An electrode was produced from the obtained electrode mixture in the same manner as in Example 1-1, and electrode property evaluation and peel strength test were performed. The results are shown in Table 5.

Example 8-2
The same procedure as in Example 8-1 was performed except that the proportion of the additive was 5 parts by mass.

Example 8-3
The same procedure as in Example 1-1 was carried out except that 0.5 parts by mass of ethylene glycol monophenyl ether (hereinafter, additive 2) as an additive was further added to the electrode mixture.

Example 8-4
The same procedure as in Example 1-1 was carried out except that 0.5 parts by mass of diethylene glycol dimethyl ether (hereinafter, additive 3) as an additive was further added to the electrode mixture.

Example 8-5
The same procedure as in Example 1-1 was conducted, except that 0.5 parts by mass of dipropylene glycol dimethyl ether (hereinafter, additive 4) as an additive was further added to the electrode mixture.

[Example 8-6]
The same procedure as in Example 1-1 was conducted, except that 0.5 parts by mass of diethylene glycol diethyl ether (hereinafter, additive 5) as an additive was further added to the electrode mixture.

[Example 8-7]
The electrode mixture, wherein as an _{_{_{_{additive: CH 3 (CH 2) 17}}}} - (OCH 2 CH 2) a compound represented by 50 -OCH ₃ (hereinafter, the additive 6) except for adding 0.5 part by weight Further Were carried out in the same manner as in Example 1-1.

Comparative Example 1
The same procedure as in Example 1-1 was repeated except that no dispersant was added.

[Comparative Examples 2 to 7]
The same procedure as in Examples 2 to 7 was carried out, respectively, except that no dispersant was added.

INDUSTRIAL APPLICABILITY The present invention can be used as a binder composition used to bond a current collector and an electrode active material in a non-aqueous electrolyte secondary battery.

Claims

A binder composition used to bind an electrode active material to a current collector,
A binder composition comprising an adhesive resin and a dispersant, wherein the dispersant is a compound represented by the following formula (I) or (II).

(In formula (I), X 6 independently represents a hydrogen atom or a methyl group, X 1 represents a methylene group, N—X 2 or O, and X 2 and X 3 independently represent H, —NH 2 , A hydrocarbon group having 1 to 8 carbon atoms,-(A 1 O) 1 R 1 (wherein A 1 is an alkylene group having 2 to 4 carbon atoms, 1 is an integer of 1 to 5 and R 1 is H or Or an alkyl group having 1 to 8 carbon atoms, or -A 2 NX 4 X 5 (wherein A 2 is an alkylene group having 1 to 4 carbon atoms, and X 4 and X 5 are independently H or 1 to carbon atoms Represents a hydrocarbon group of 4))

(In the formula (II), m is an integer of 1 to 50, A 3 is an alkylene group having 2 to 4 carbon atoms, R 2 and R 3 are independently H, an alkyl group having 1 to 18 carbon atoms or carbon atoms Represents 1 to 18 aminoalkyl groups)
In the compound represented by the above formula (I), X 1 is NH or O, X 3 is H, -NH 2 , a hydrocarbon group having 1 to 6 carbon atoms, -C 2 H 4 OH or -C 2 The binder composition according to claim 1, which is a compound that is H 4 NH 2 .
The compound represented by the above formula (II) is a compound wherein R 2 and R 3 are independently H, or an alkyl group having 1 to 2 carbon atoms or an aminoalkyl group, and m is 1 or 2. The binder composition according to claim 1, characterized in that:
The above dispersants are morpholine, 4-methylmorpholine, 4-ethylmorpholine, 4- (2-hydroxyethyl) morpholine, 4- (1-cyclohexenyl) morpholine, 4- (2-aminoethyl) morpholine, 4-amino Morpholine, piperazine, 1-methylpiperazine, N- (2-aminoethyl) piperazine, 1- (2-hydroxyethyl) piperazine, monoethanolamine, N-methylethanolamine, N-ethylethanolamine, and 2- (2 The binder composition according to any one of claims 1 to 3, which is at least one selected from the group consisting of -aminoethylamino) ethanol.
The binder composition according to any one of claims 1 to 4, further comprising an additive represented by the following formula (III).
R 4 -O- (A 4 O) n -R 5 (III)
(In the formula (III), n is an integer of 1 to 100, R 4 is a hydrocarbon group having 1 to 18 carbon atoms, R 5 is H or an alkyl group having 1 to 4 carbon atoms, and A 4 is 2 to 4 carbon atoms Is an alkylene group of
The additives described above, n is 1-4, the binder composition according to claim 5, characterized in that A 4 is a compound which is ethylene or propylene group.
The binder composition according to claim 5, wherein the additive is ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, dipropylene glycol dimethyl ether or diethylene glycol diethyl ether.
The binder composition according to any one of claims 1 to 7, wherein the adhesive resin is a vinylidene fluoride resin, an acrylic resin, or a synthetic rubber.
The binder composition according to any one of claims 1 to 8, wherein the adhesive resin is polyvinylidene fluoride, polyacrylic acid, polyacrylonitrile, or styrene butadiene rubber.
An electrode mixture comprising the binder composition according to any one of claims 1 to 9 and an electrode active material.
An electrode characterized in that an electrode mixture layer formed of the electrode mixture according to claim 10 is provided on a current collector.
A non-aqueous electrolyte secondary battery comprising the electrode according to claim 11.
A dispersant for adding to a binder composition used to bind an electrode active material to a current collector,
The binder composition is a binder composition containing an adhesive resin,
A dispersant comprising a compound represented by the following formula (I) or (II) as a main component.

(In formula (I), X 6 independently represents a hydrogen atom or a methyl group, X 1 represents a methylene group, N—X 2 or O, and X 2 and X 3 independently represent H, —NH 2 , A hydrocarbon group having 1 to 8 carbon atoms,-(A 1 O) 1 R 1 (wherein A 1 is an alkylene group having 2 to 4 carbon atoms, 1 is an integer of 1 to 5 and R 1 is H or Or an alkyl group having 1 to 8 carbon atoms, or -A 2 NX 4 X 5 (wherein A 2 is an alkylene group having 1 to 4 carbon atoms, and X 4 and X 5 are independently H or 1 to carbon atoms Represents a hydrocarbon group of 4))

(In the formula (II), m is an integer of 1 to 50, A 3 is an alkylene group having 2 to 4 carbon atoms, R 2 and R 3 are independently H, an alkyl group having 1 to 18 carbon atoms or carbon atoms Represents 1 to 18 aminoalkyl groups)