CN110832683A - Binder for electrode, binder composition for electrode, electrode material, electrode, and electricity storage device - Google Patents
Binder for electrode, binder composition for electrode, electrode material, electrode, and electricity storage device Download PDFInfo
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- CN110832683A CN110832683A CN201880044362.7A CN201880044362A CN110832683A CN 110832683 A CN110832683 A CN 110832683A CN 201880044362 A CN201880044362 A CN 201880044362A CN 110832683 A CN110832683 A CN 110832683A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/38—Carbon pastes or blends; Binders or additives therein
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides an electrode binder with excellent adhesiveness when used in an electrode. A binder for an electrode, comprising a polymer containing a structural unit (A) derived from a monomer having a hydroxyl group represented by the following general formula (1); a structural unit (B) derived from a (meth) acrylate monomer having a structural unit (B-1), wherein the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4 to 6 carbon atoms; a structural unit (C) derived from a (meth) acrylic acid monomer; and a structural unit (D) derived from a 5-or less-functional polyfunctional (meth) acrylate monomer; the polymer has 80 to 95 mass% of the structural unit(B) And has 3.5 to 15 mass% of the structural unit (C),
in the formula (1), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30.
Description
Technical Field
The present invention relates to a binder for an electrode used for a secondary battery such as a primary battery, a lithium ion secondary battery, and a nickel hydrogen secondary battery, and an electricity storage device such as an electrochemical capacitor, and particularly relates to a binder for an electrode for a nonaqueous electrolyte electricity storage device using a nonaqueous electrolyte such as an organic solvent as an electrolyte, a binder composition for an electrode containing the binder for an electrode, an electrode material, an electrode, and an electricity storage device provided with the electrode.
Background
Electric storage devices such as lithium ion secondary batteries and electrochemical capacitors are used in electronic devices such as mobile phones, notebook computers, and video cameras (camcorders). Recently, due to the increase in awareness of environmental protection and the correction of related laws, the battery has been also used for storage batteries for household use and for vehicle-mounted applications such as electric vehicles and hybrid electric vehicles.
In addition, in addition to these applications, improvement of components such as electrodes has been demanded in addition to improvement of the performance of the power storage device. The electrode used in such an electric storage device is generally obtained by applying an electrode material composed of an active material, a conductive assistant, a binder, and a solvent to a current collector and drying the applied electrode material.
Therefore, in recent years, improvement of a binder for an electrode has been attempted. It has been proposed to improve the adhesion between active materials, the adhesion between the active materials and a conductive additive, and the adhesion between the active materials and a current collector by improving a binder, and to improve electrical characteristics (for example, cycle characteristics, output characteristics at low temperatures, and reduction in resistance).
The binder is required to have excellent adhesiveness when used for an electrode and to impart excellent electrical characteristics to the power storage device, and a new binder is proposed in patent document 1, for example.
However, in recent years, a binder having particularly excellent adhesiveness has been required, and further studies have been required.
Documents of the prior art
Patent document
Patent document 1: international publication No. 2013/180103
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrode binder having excellent adhesiveness when used for an electrode.
Means for solving the problems
The present inventors have conducted extensive studies to achieve the above object, and as a result, have found that a polymer comprising a structural unit (a) derived from a monomer having a hydroxyl group represented by the following general formula (1); a structural unit (B) derived from a (meth) acrylate monomer having a structural unit (B-1), wherein the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4 to 6 carbon atoms, and a structural unit (C) derived from a (meth) acrylic acid monomer; and a structural unit (D) derived from a 5-or less-functional polyfunctional (meth) acrylate monomer; the polymer has 80-95 mass% of structural unit (B) and 3.5-15 mass% of structural unit (C). That is, the present invention relates to the following.
[ solution 1]
In the general formula (1), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30.
That is, the present invention relates to the following.
Scheme 1. a binder for an electrode, which contains a polymer,
the polymer contains a structural unit (A) derived from a monomer having a hydroxyl group represented by the following general formula (1),
a structural unit (B) derived from a (meth) acrylate monomer having a structural unit (B-1), wherein the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4 to 6 carbon atoms,
structural unit (C) derived from a (meth) acrylic monomer, and
structural units (D) derived from a 5-or less-functional polyfunctional (meth) acrylate monomer,
the polymer has 80 to 95 mass% of the structural unit (B) and 3.5 to 15 mass% of the structural unit (C),
[ solution 2]
In the formula (1), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30.
The binder for an electrode according to claim 1, wherein n in the general formula (1) is an integer of 4 to 20.
The binder for an electrode according to claim 1 or 2, wherein the polyfunctional (meth) acrylate monomer having 5 or less functions in the structural unit (D) is a compound represented by the following general formula (3),
[ solution 3]
In the formula (3), R11Respective phase ofIs the same or different and is a hydrogen atom or a methyl group, R12An organic group having 2 to 100 carbon atoms and a valence of 5 or less, and m is an integer of 5 or less.
The binder for an electrode according to any one of claims 1 to 3, wherein the 5-or less-functional polyfunctional (meth) acrylate monomer in the structural unit (D) is a 3-to 5-functional (meth) acrylate.
The binder for an electrode according to any one of claims 1 to 4, wherein the structural unit (B-1) is contained in an amount of 50 to 95% by mass.
The binder for an electrode according to any one of claims 1 to 5, wherein the structural unit (A) is contained in an amount of 0.5 to 15% by mass.
The binder for an electrode according to any one of claims 1 to 6, wherein the structural unit (D) is contained in an amount of 0.1 to 10 mass%.
The binder composition for an electrode according to claim 8, which comprises the binder for an electrode according to any one of claims 1 to 7.
An electrode material according to claim 9, which comprises the binder for an electrode according to any one of claims 1 to 7.
An electrode according to claim 10, comprising the binder for an electrode according to any one of claims 1 to 7 and an active material.
The power storage device according to claim 11, comprising the electrode according to claim 8.
Effects of the invention
According to the present invention, a binder for an electrode excellent in adhesiveness when used for an electrode can be provided. In addition, according to the present invention, a binder composition for an electrode, an electrode material, and an electrode, which contain the binder for an electrode, and an electricity storage device provided with the electrode, can be provided.
The binder for an electrode of the present invention has excellent adhesiveness. In particular, the binder for an electrode of the present invention can exhibit excellent binding force when used in a small-sized battery (for example, a battery for a mobile phone, a tablet terminal, a notebook computer, or the like) having a higher density than a large-sized battery. Therefore, the electrode using the binder for an electrode of the present invention and the power storage device provided with the electrode are particularly useful for batteries of mobile phones, tablet terminals, notebook computers, and the like.
Detailed Description
In this specification, the electric storage device includes a primary battery, a secondary battery (a lithium ion secondary battery, a nickel hydrogen secondary battery, and the like), and an electrochemical capacitor. In the present specification, "(meth) acrylate" means "acrylate or methacrylate", and similar terms are used.
< 1. Binder for electrode >
The binder for an electrode is characterized by comprising a polymer, wherein the polymer comprises a structural unit (A) derived from a monomer having a hydroxyl group represented by the following general formula (1), a structural unit (B) derived from a (meth) acrylate monomer having a structural unit (B-1), the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4-6 carbon atoms, a structural unit (C) derived from a (meth) acrylic acid monomer, and a structural unit (D) derived from a polyfunctional (meth) acrylate monomer having 5 or less functions, and the polymer has 80-95 mass% of the structural unit (B) and 3.5-15 mass% of the structural unit (C).
[ solution 4]
In the general formula (1), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30.
The structural units of the polymer of the present invention are described in detail below.
The structural unit (a) is derived from a monomer having a hydroxyl group represented by the above general formula (1). In the general formula (1), R1Selected from hydrogen atoms or straight chain or branched chain alkyl groups with 1-4 carbon atoms.
In the general formula (1), as R1Preferred examples thereof include a hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group and the like. Preferably a hydrogen atom or a methyl group. Namely, in the structural unit (A)The monomer having a hydroxyl group is preferably (R)1(meth) acrylate monomer which is a hydrogen atom or a methyl group.
In the general formula (1), (C)xH2xO) is a straight chain or branched alkyl ether group, x is an integer of 2 to 8, preferably an integer of 2 to 7, more preferably an integer of 2 to 6.
In the general formula (1), n is an integer of 2 to 30, preferably an integer of 3 to 25, and more preferably an integer of 4 to 20.
The structural unit (a) is preferably derived from a monomer having a hydroxyl group represented by the following general formula (2).
[ solution 5]
In the general formula (2), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, o is an integer of 0 to 30, p is an integer of 0 to 30, and o + p is 2 to 30. Here, o and p merely indicate the composition ratio of the structural units, and do not merely mean a structural unit consisting of (C)2H4Blocks of repeating units of O) and (C)3H6O) may be (C)2H4Repeating units of O) and (C)3H6O) or a compound in which the random portion and the block portion are mixed.
In the general formula (2), as R1Preferred examples thereof include a hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group and the like. Preferably a hydrogen atom or a methyl group. That is, in the structural unit (A), the monomer having a hydroxyl group is preferably (R)1(meth) acrylate monomer which is a hydrogen atom or a methyl group.
In the general formula (2), o is an integer of 0 to 30, p is an integer of 0 to 30, o + p is 2 to 30, preferably o is an integer of 0 to 25, p is an integer of 0 to 25, o + p is 3 to 25, particularly preferably o is an integer of 0 to 20, p is an integer of 0 to 20, and o + p is 4 to 20.
Specific examples of the monomer having a hydroxyl group represented by the general formula (1) include diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate, tetrapropylene glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate, polyethylene glycol-propylene glycol-mono (meth) acrylate, polyethylene glycol-tetramethylene glycol-mono (meth) acrylate, and the like. These monomers may be used singly or in combination of two or more. Among them, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, tetrapropylene glycol mono (meth) acrylate, and polypropylene glycol mono (meth) acrylate are preferable.
The number of the structural units (A) may be 1, or 2 or more.
The lower limit of the ratio of the structural unit (a) in the polymer is preferably 0.5% by mass or more, more preferably 1.5% by mass or more, and particularly preferably 2.5% by mass or more. The upper limit of the ratio of the structural unit (a) in the polymer is preferably 15% by mass or less, more preferably 12% by mass or less, and particularly preferably 10% by mass or less.
The structural unit (B) is a structural unit derived from a (meth) acrylate monomer. The polymer has 80 to 95 mass% of a structural unit (B).
The structural unit (B) has a structural unit (B-1), and the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4 to 6 carbon atoms. The structural unit (B) may be composed of only the structural unit (B-1), or may have the structural unit (B-1) and a structural unit (B-2) derived from a (meth) acrylate monomer other than a (meth) acrylate monomer having an alkyl group with 4 to 6 carbon atoms.
Specific examples of the preferable structural unit (B-1) include structural units derived from the following alkyl (meth) acrylates, such as n-butyl acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, and isohexyl (meth) acrylate, and more preferably structural units derived from the following (meth) acrylate monomers having an alkyl group of 4 to 5 carbon atoms, such as n-butyl acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, and isoamyl (meth) acrylate. The structural unit (B) may have 1 or 2 or more types of the structural unit (B-1).
Examples of the structural unit (B-2) include structural units derived from the following alkyl (meth) acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate, and structural units derived from (meth) acrylate monomers having an alkyl group having 7 to 12 carbon atoms are preferable. The structural unit (B) may have 1 or 2 or more types of the structural unit (B-2).
The lower limit of the ratio of the structural unit (B) in the polymer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit of the ratio of the structural unit (B) in the polymer is preferably 95% by mass or less, more preferably 94% by mass or less, and particularly preferably 92% by mass or less.
The lower limit of the proportion of the structural unit (B-1) in the polymer is preferably 50% by mass or more, more preferably 65% by mass or more, and particularly preferably 80% by mass or more. The upper limit of the proportion of the structural unit (B-1) in the polymer is preferably 95% by mass or less, more preferably 94% by mass or less, and particularly preferably 92% by mass or less.
In the polymer, the mass ratio of the structural unit (B-1) to the structural unit (A) is preferably 7: 1-35: 1, more preferably 7.5: 1-30: 1, particularly preferably 8: 1-25: 1.
the upper limit of the ratio of the structural unit (B-2) in the polymer is preferably 35% by mass or less, more preferably 23% by mass or less, and particularly preferably 10% by mass or less. The lower limit of the proportion of the structural unit (B-2) in the polymer is 0% by mass or more, may be 3% by mass or more, and may be 5% by mass or more.
The structural unit (C) is a structural unit derived from a (meth) acrylic acid monomer. The polymer has 3.5 to 15 mass% of a structural unit (C).
Examples of the structural unit (C) include structural units derived from compounds selected from acrylic acid and methacrylic acid. The number of the structural units (C) in the polymer may be 1, or 2 or more.
The lower limit of the ratio of the structural unit (C) in the polymer is preferably 3.5% by mass or more, more preferably 4% by mass or more, and particularly preferably 5% by mass or more. The upper limit of the ratio of the structural unit (C) is preferably 15% by mass or less, more preferably 13% by mass or less, and particularly preferably 12% by mass or less.
The structural unit (D) is a structural unit derived from a 5-or less-functional polyfunctional (meth) acrylate monomer. The structural unit (D) is preferably a structural unit derived from the following general formula (3).
[ solution 6]
In the general formula (3), R11Each being the same or different and being a hydrogen atom or a methyl group, R12An organic group having 2 to 100 carbon atoms and a valence of 5 or less, and m is an integer of 5 or less.
In the general formula (3), m is preferably 2 to 5 (i.e., the structural unit (D) is a structural unit derived from a 2-to 5-functional (meth) acrylate), more preferably 3 to 5 (i.e., the structural unit (D) is a structural unit derived from a 3-to 5-functional (meth) acrylate), and particularly preferably 3 to 4 (i.e., the structural unit (D) is a structural unit derived from a 3-to 4-functional (meth) acrylate).
Specific examples of the structural unit derived from a 2-functional (meth) acrylate among the structural units (D) include structural units derived from the following 2-functional (meth) acrylates, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, di (meth) acrylate
Alkylene glycol di (meth) acrylate, bis (meth) acryloyloxyethyl phosphate, and the like.
Specific examples of the structural unit derived from a 3-functional (meth) acrylate among the structural units (D) include structural units derived from the following 3-functional (meth) acrylates, trimethylolpropane tri (meth) acrylate, trimethylolpropane EO addition tri (meth) acrylate, trimethylolpropane PO addition tri (meth) acrylate, pentaerythritol tri (meth) acrylate, 2,2, 2-tri (meth) acryloyloxymethylethylsuccinic acid, ethoxylated isocyanuric acid tri (meth) acrylate, epsilon-caprolactone-modified tri (2- (meth) acryloyloxyethyl) isocyanurate, glycerol EO addition tri (meth) acrylate, glycerol PO addition tri (meth) acrylate, and tris (meth) acryloyloxyethyl phosphate. Among them, preferred are structural units derived from the following 3-functional (meth) acrylates, trimethylolpropane tri (meth) acrylate, trimethylolpropane EO addition tri (meth) acrylate, pentaerythritol tri (meth) acrylate.
Specific examples of the structural unit derived from a 4-functional (meth) acrylate among the structural units (D) include the following structural units derived from a 4-functional (meth) acrylate, di-trimethylolpropane tetra (meth) acrylate, pentaerythritol EO-addition tetra (meth) acrylate, and the like.
Specific examples of the structural unit derived from a 5-functional (meth) acrylate in the structural unit (D) include structural units derived from dipentaerythritol penta (meth) acrylate.
The lower limit of the ratio of the structural unit (D) in the polymer is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.2% by mass or more. The upper limit of the ratio of the structural unit (D) is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less.
The mass ratio of the structural unit (D) to the structural unit (a) in the polymer is preferably 0.03: 1-1.5: 1, more preferably 0.05: 1-1: 1, particularly preferably 0.08: 1-0.3: 1.
as the polymer, in addition to the above-mentioned structural units, as structural units derived from other monomers, there may be mentioned structural units derived from monomers selected from fumaric acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, acrylonitrile, methacrylonitrile, α -chloroacrylonitrile, crotononitrile, α -ethylacrylonitrile, α -cyanoacrylate, vinylidene cyanide, and fumaronitrile.
As a method for obtaining the polymer, a common emulsion polymerization method, a soap-free emulsion polymerization method, or the like can be used. Specifically, a composition containing a monomer, an emulsifier, a polymerization initiator, water, and, if necessary, a dispersant, a chain transfer agent, a pH adjuster, etc. is stirred in a closed container with a stirrer and a heating device at room temperature under an inert gas atmosphere, thereby emulsifying the monomer, etc. in water. As a method of emulsification, a method based on stirring, shearing, ultrasonic waves, or the like can be applied, and a stirring blade, a homogenizer, or the like can be used. Then, the temperature is increased while stirring to initiate polymerization, whereby a spherical polymer latex in which a polymer is dispersed in water can be obtained. The method of adding the monomer in the polymerization may be, for example, dropping the monomer, dropping the pre-emulsion, or the like, or 2 or more of these methods may be used in combination, in addition to the single addition. The pre-emulsion is added dropwise by a method of previously emulsifying a monomer, an emulsifier, water, etc. and adding the emulsion dropwise.
The emulsifier used in the present invention is not particularly limited. The emulsifier is a surfactant comprising a reactive surfactant having a reactive group. Nonionic surfactants, anionic surfactants, and the like, which are generally used in emulsion polymerization, can be used.
Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polycyclic phenyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, and examples of the reactive nonionic surfactant include latex PD-420, 430, 450 (manufactured by Kao corporation), Adeka Reasoap ER (manufactured by Adeka corporation), Aqualon RN (manufactured by first Industrial pharmaceutical Co., Ltd.), Antox LMA (manufactured by Nippon emulsifier Co., Ltd.), Antox EMH (manufactured by Nippon emulsifier Co., Ltd.), and the like.
Examples of the anionic surfactant include metal salts, ammonium salts, triethanolammonium salts, and phosphate surfactants of sulfate type, carboxylic acid type, and sulfonic acid type. The sulfuric acid ester type, sulfonic acid type, and phosphoric acid ester type are preferable, and the sulfuric acid ester type is particularly preferable. Typical examples of the sulfate-type anionic surfactant include metal alkylsulfates such as lauryl sulfuric acid, ammonium or triethanolamine alkylsulfates, metal polyoxyethylene alkylether sulfates such as polyoxyethylene lauryl ether sulfuric acid, polyoxyethylene isodecyl ether sulfuric acid, and polyoxyethylene tridecyl ether sulfuric acid, ammonium salts, and triethanolamine polyoxyethylene alkylether sulfates; specific examples of the sulfate-type reactive anionic surfactant include Latemul PD-104 and 105 (manufactured by Kao corporation), Adeka Reasoap SR (manufactured by Adeka corporation), Aqualon HS (manufactured by first Industrial pharmaceutical Co., Ltd.), and Aqualon KH (manufactured by first Industrial pharmaceutical Co., Ltd.). Preferred examples thereof include sodium lauryl sulfate, ammonium lauryl sulfate, triethanolamine lauryl sulfate, sodium dodecylbenzenesulfonate, and Latemul PD-104.
These nonionic surfactants and/or anionic surfactants may be used in an amount of 1 or 2 or more.
The reactivity of the reactive surfactant means that the reactive surfactant contains a reactive double bond and undergoes a polymerization reaction with a monomer at the time of polymerization. That is, the reactive surfactant functions as an emulsifier for the monomer at the time of polymerization for preparing the polymer, and is covalently bonded to a part of the polymer after polymerization to form a state of incorporation. Therefore, the dispersion of the emulsion polymerization and the produced polymer is good, and the physical properties (flexibility and adhesiveness) as a binder for an electrode are excellent.
The amount of the structural unit of the emulsifier may be an amount generally used in the emulsion polymerization method. Specifically, the amount of the monomer to be charged (100 mass%) is in the range of 0.01 to 25 mass%, preferably 0.05 to 20 mass%, and more preferably 0.1 to 20 mass%.
The polymerization initiator used in the present invention is not particularly limited, and a polymerization initiator generally used in emulsion polymerization and suspension polymerization can be used. Preferably an emulsion polymerization process. The emulsion polymerization method uses a water-soluble polymerization initiator, and the suspension polymerization method uses an oil-soluble polymerization initiator.
Specific examples of the water-soluble polymerization initiator include water-soluble polymerization initiators represented by persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, 2-2 ' -azobis [2- (2-imidazolin-2-yl) propane ] or a hydrochloride or sulfate thereof, 2 ' -azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ], 2 ' -azobisisobutylamidine or a hydrochloride or sulfate thereof, 3 ' - [ azobis [ (2, 2-dimethyl-1-iminoethane-2, 1-diyl) imino ] ] bis (propionic acid), 2 ' - [ azobis (dimethylmethylene) ] bis (2-imidazoline) and other water-soluble azo compound polymerization initiators.
As the oil-soluble polymerization initiator, organic peroxides such as cumene hydroperoxide, benzoyl peroxide, acetyl peroxide and tert-butyl hydroperoxide, oil-soluble azo compound polymerization initiators such as azobisisobutyronitrile and 1, 1' -azobis (cyclohexanecarbonitrile), and redox initiators are preferable. These polymerization initiators may be used in 1 kind or in combination of 2 or more kinds.
The amount of the polymerization initiator to be used may be an amount generally used in emulsion polymerization or suspension polymerization. Specifically, the amount of the monomer to be charged (100 mass%) is in the range of 0.01 to 10 mass%, preferably 0.01 to 5 mass%, and more preferably 0.02 to 3 mass%.
Specific examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan and n-octadecyl mercaptan, xanthogen compounds such as 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene, dimethyl xanthogen disulfide and diisopropyl xanthogen disulfide, thiuram compounds such as terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide, phenol compounds such as 2, 6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and tetrabrominated carbon, vinyl ethers such as α -benzyloxystyrene, α -benzyloxyacrylonitrile and α -benzyloxyacrylamide, triphenyl ethane, pentaphenyl ethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid and thioglycolic acid-2-ethylhexyl, and the amount of the one or more of these chain transfer agents is not particularly limited to 100 parts by mass.
The polymerization time and polymerization temperature of the polymer are not particularly limited. The polymerization temperature is usually 20 to 100 ℃ and the polymerization time is usually 0.5 to 100 hours.
The polymer obtained by the above method may be adjusted in pH by using a base as a pH adjuster as needed. Specific examples of the base include alkali metal (Li, Na, K, Rb, Cs) hydroxides, ammonia, inorganic ammonium compounds, organic amine compounds, and the like. The pH range is 2-11, preferably 3-10, and more preferably 4-9.
The electrode binder of the present invention has a polymer, but may contain water or other substances such as an emulsifier in the polymer or may be attached to the outside of the polymer. The amount of the substance obtained inside or attached to the outside is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less, per 100 parts by mass of the polymer.
< 2. Binder composition for electrode >
The binder composition for an electrode of the present invention contains the above-mentioned "binder for an electrode 1" and a solvent at the same time, and may be a composition in which the binder for an electrode is dispersed in a solvent. The solvent can be water or organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol (pentanol), hexanol, heptanol, octanol, nonanol, decanol, and pentanol (amyl alcohol); ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; diethyl etherTwo, two
Ethers such as alkane and tetrahydrofuran; amide polar organic solvents such as N, N-dimethylformamide and N-methyl-2-pyrrolidone (NMP); and aromatic hydrocarbons such as toluene, xylene, chlorobenzene, o-dichlorobenzene, and p-dichlorobenzene.
The binder composition for an electrode of the present invention is preferably an aqueous binder composition in which a binder for an electrode is dispersed in water.
The binder composition for an electrode of the present invention may be an emulsion obtained by using an emulsion produced when a polymer is obtained.
The content of the binder for an electrode in the binder composition for an electrode of the present invention is not particularly limited, and is preferably 0.2 to 80 mass%, more preferably 0.5 to 70 mass%, and particularly preferably 0.5 to 60 mass% in terms of the solid content concentration of the binder for an electrode. In addition, the solid components in the binder composition can be generally considered as a polymer and an emulsifier (only when the polymer is used in emulsion polymerization).
< 3. electrode Material
The electrode material of the present invention contains at least an active material and the binder for an electrode of the present invention described in the section "binder for an electrode" 1, and may further contain a conductive auxiliary agent. In the production of the electrode material of the present invention, the binder composition for an electrode of the present invention described in the column "binder composition for an electrode" containing the binder for an electrode of the present invention and a solvent at the same time can be used. Specifically, the positive electrode material for a positive electrode contains a positive electrode active material and the binder for an electrode of the present invention, and may further contain a conductive auxiliary agent; the negative electrode material for a negative electrode contains a negative electrode active material, the binder for an electrode of the present invention, and may further contain a conductive auxiliary.
The positive electrode active material is composed of AMO2、AM2O4、A2MO3、AMBO4Any one of the compositions is composed of an alkali metal-containing composite oxide. A is an alkali metal, MComposed of a single or 2 or more transition metals, and a part of them may contain a non-transition metal. B comprises P, Si or a mixture thereof. The positive electrode active material is preferably a powder. The particle size is preferably 50 μm or less, more preferably 20 μm or less. These active materials have an electromotive force of 3V (vs. Li/Li +) or more.
Preferable specific example of the positive electrode active material includes LixCoO2，LixNiO2，LixMnO2，LixCrO2，LixFeO2，LixCoaMn1-aO2，LixCoaNi1-aO2，LixCoaCr1-aO2，LixCoaFe1-aO2，LixCoaTi1-aO2，LixMnaNi1- aO2，LixMnaCr1-aO2，LixMnaFe1-aO2，LixMnaTi1-aO2，LixNiaCr1-aO2，LixNiaFe1-aO2，LixNiaTi1-aO2，LixCraFe1-aO2，LixCraTi1-aO2，LixFeaTi1-aO2，LixCobMncNi1-b-cO2，LixNiaCobAlcO2，LixCrbMncNi1-b-cO2，LixFebMncNi1-b-cO2，LixTibMncNi1-b-cO2，LixMn2O4，LixMndCo2-dO4，LixMndNi2- dO4，LixMndCr2-dO4，LixMndFe2-dO4，LixMndTi2-dO4，LiyMnO3，LiyMneCo1-eO3，LiyMneNi1-eO3，LiyMneFe1-eO3，LiyMneTi1-eO3，LixCoPO4，LixMnPO4，LixNiPO4，LixFePO4，LixCofMn1-fPO4，LixCofNi1-fPO4，LixCofFe1-fPO4，LixMnfNi1-fPO4，LixMnfFe1-fPO4，LixNifFe1-fPO4，LiyCoSiO4，LiyMnSiO4，LiyNiSiO4，LiyFeSiO4，LiyCogMn1-gSiO4，LiyCogNi1-gSiO4，LiyCogFe1-gSiO4，LiyMngNi1-gSiO4，LiyMngFe1-gSiO4，LiyNigFe1-gSiO4，LiyCoPhSi1-hO4，LiyMnPhSi1-hO4，LiyNiPhSi1-hO4，LiyFePhSi1-hO4，LiyCogMn1-gPhSi1-hO4，LiyCogNi1-gPhSi1-hO4，LiyCogFe1-gPhSi1- hO4，LiyMngNi1-gPhSi1-hO4，LiyMngFe1-gPhSi1-hO4，LiyNigFe1-gPhSi1-hO4And the like lithium-containing composite oxides. (here, x is 0.01 to 1.2, y is 0.01 to 2.2, a is 0.01 to 0.99, b is 0.01 to 0.98, c is 0.01 to 0.98, and b + c is 0.02 to 0.99, d is 1.49 to 1.99, e is 0.01 to 0.99, f is 0.01 to 0.99, g is 0.01 to 0.99, and h is 0.01 to 0.99).
Among the above-mentioned preferred positive electrode active materials, a more preferred positive electrode active material includes LixCoO2，LixNiO2，LixMnO2，LixCrO2，LixCoaNi1-aO2，LixMnaNi1-aO2，LixCobMncNi1-b-cO2，LixNiaCobAlcO2，LixMn2O4，LiyMnO3，LiyMneFe1-eO3，LiyMneTi1-eO3，LixCoPO4，LixMnPO4，LixNiPO4，LixFePO4，LixMnfFe1-fPO4. (here, x is 0.01 to 1.2, y is 0.01 to 2.2, a is 0.01 to 0.99, b is 0.01 to 0.98, c is 0.01 to 0.98, b + c is 0.02 to 0.99, d is 1.49 to 1.99, e is 0.01 to 0.99, and f is 0.01 to 0.99.) the values of x and y are increased and decreased by charging and discharging.)
The negative electrode active material is a powder made of a carbon material (natural graphite, artificial graphite, amorphous carbon, or the like) having a structure (porous structure) capable of absorbing and releasing lithium ions, or a powder made of a metal such as lithium, an aluminum compound, a tin compound, a silicon compound, or a titanium compound capable of absorbing and releasing lithium ions. The particle diameter is preferably 10nm or more and 100 μm or less, and more preferably 20nm or more and 20 μm or less. In addition, a mixed active material of a metal and a carbon material may also be used. The negative electrode active material preferably has a porosity of about 70%.
The content of the active material in the electrode material is not particularly limited, and may be, for example, about 99.9 to 50 mass%, more preferably about 99.5 to 70 mass%, and still more preferably about 99 to 85 mass%. The active substances may be used alone in 1 kind, or in combination of 2 or more kinds.
When a conductive aid is used, a known conductive aid can be used, and examples thereof include conductive carbon black such as graphite, furnace black, acetylene black, and ketjen black, carbon fibers such as carbon nanotubes, metal powder, and the like. These conductive aids may be used in 1 kind or 2 or more kinds.
When the conductive aid is used, the content of the conductive aid is not particularly limited, and is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less, per 100 parts by mass of the active material. When the conductive additive is contained in the positive electrode material, the lower limit of the content of the conductive additive is usually 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.5 parts by mass or more, and 2 parts by mass or more.
The electrode material of the present invention may contain a thickener as necessary. The type of the thickener is not particularly limited, and sodium salt, ammonium salt, polyvinyl alcohol, polyacrylic acid, and salts thereof of cellulose-based compounds are preferable.
Examples of the sodium salt or ammonium salt of the cellulose compound include sodium salts or ammonium salts of alkyl celluloses obtained by substituting cellulose polymers with various derivative groups. Specific examples thereof include sodium salts, ammonium salts, and triethanolammonium salts of methylcellulose, methylethylcellulose, ethylcellulose, and carboxymethylcellulose (CMC). Sodium or ammonium salts of carboxymethyl cellulose are particularly preferred. These thickeners may be used alone in 1 kind, or two or more kinds may be used in combination in an arbitrary ratio.
When the thickener is used, the content of the thickener is not particularly limited, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by mass of the active material. When the thickener is contained, the lower limit of the content of the thickener is usually 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.5 parts by mass or more, and 1 part by mass or more.
The electrode material of the present invention may contain water to be in a slurry state. The water is not particularly limited, and water that is generally used may be used. Specific examples thereof include tap water, distilled water, ion-exchanged water, and ultrapure water. Among them, distilled water, ion-exchanged water and ultrapure water are preferable.
When the electrode material of the present invention is used as a slurry, the solid content concentration of the slurry is preferably 10 to 90 mass%, more preferably 20 to 85 mass%, and particularly preferably 30 to 80 mass%.
When the electrode material of the present invention is used in the form of slurry, the amount of the polymer in the solid content of the slurry is preferably 0.1 to 15% by mass, more preferably 0.2 to 10% by mass, and particularly preferably 0.3 to 7% by mass.
The method for producing the electrode material is not particularly limited, and any method may be used as long as the positive electrode active material or the negative electrode active material, the binder for an electrode of the present invention, the conductive assistant, water, and the like are dispersed using a common stirrer, a disperser, a kneader, a planetary ball mill, a homogenizer, or the like. In order to improve the efficiency of dispersion, heating may be performed within a range that does not affect the material.
< 4. electrode >
The electrode of the present invention is characterized by comprising the electrode material and current collector of the present invention described in the aforementioned column "3. electrode material". The details of the electrode material of the present invention are as described above.
For the electrode of the present invention, a known current collector can be used. Specifically, as the positive electrode, metals such as aluminum, nickel, stainless steel, gold, platinum, and titanium can be used. As the negative electrode, a metal such as copper, nickel, stainless steel, gold, platinum, or titanium can be used.
The method for producing the electrode is not particularly limited, and a general method can be used. The battery material can be uniformly applied to the surface of the current collector (metal electrode substrate) in an appropriate thickness by a doctor blade method, an applicator method, a screen printing method, or the like.
For example, in the doctor blade method, a slurry for a battery electrode is applied to a metal electrode substrate and then homogenized by a doctor blade having a predetermined slit width to form an appropriate thickness. After the electrode is coated with the active material, it is dried, for example, with hot air at 100 ℃ or in a vacuum state at 80 ℃ to remove excess organic solvent and water. The dried electrode was press-molded by a press to produce an electrode material. After pressing, heat treatment may be applied again to remove water, solvents, emulsifiers, etc.
The electrode is preferably pressed so that the density of the electrode material is preferably 3.2g/cc or more. As described above, the binder for an electrode of the present invention can exhibit excellent binding force when used in a small-sized battery (for example, a battery for a mobile phone, a tablet terminal, a notebook computer, or the like) having a higher density than a large-sized battery. Therefore, in the electrode of the present invention, when the electrode material density has such a value, particularly excellent adhesion can be exhibited. The upper limit of the density of the electrode material is usually 4.5g/cc or less.
< 5. electric storage device
The electric storage device of the present invention is characterized by including the positive electrode, the negative electrode, and the electrolytic solution described in the column "4. electrode". That is, the electrode used in the power storage device of the present invention contains the electrode material of the present invention, that is, the binder for an electrode of the present invention. The details of the electrode of the present invention are as described above. In the power storage device of the present invention, any electrode may be used as long as it is obtained by using an electrode material containing the binder for an electrode of the present invention for at least one of a positive electrode and a negative electrode, and a known electrode may be used for an electrode that does not use an electrode material containing the binder for an electrode of the present invention.
The electrolyte is not particularly limited, and a known electrolyte can be used. Specific examples of the electrolytic solution include a solution containing an electrolyte and a solvent. The electrolyte and the solvent may be used alone in 1 kind, or in combination of 2 or more kinds.
The electrolyte may be a lithium salt compound, and specifically LiBF is exemplified4、LiPF6、LiClO4、LiCF3SO3、LiN(CF3SO2)2，LiN(C2F5SO2)2，LiN[CF3SC(C2F5SO2)3]2And the like, but is not limited thereto.
Examples of the electrolyte other than the lithium salt compound include tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, and the like.
Examples of the solvent used for the electrolytic solution include an organic solvent and an ambient temperature molten salt.
Examples of the organic solvent include aprotic organic solvents, and specifically, linear ethers such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1, 2-dimethoxyethane, 1, 2-diethoxyethane, γ -butyrolactone, tetrahydrofuran, 1, 3-dioxolane, dipropyl carbonate, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, anisole, acetate, propionate, and diethyl ether may be used, and 2 or more kinds thereof may be used in combination.
The ambient temperature molten salt is also called an ionic liquid, and is a "salt" composed of only ions (anions, cations), and particularly a liquid compound is called an ionic liquid.
The ambient temperature molten salt in the present invention means a salt that is at least partially liquid at ambient temperature, and ambient temperature means a temperature range in which the battery is supposed to normally operate. The upper limit of the temperature range in which the battery normally operates is assumed to be about 120 ℃, and in some cases, about 80 ℃, and the lower limit thereof is assumed to be about-40 ℃, and in some cases, about-20 ℃.
As the cation active species of the ambient temperature molten salt, a pyridine-based, aliphatic amine-based, or alicyclic amine-based quaternary ammonium organic cation is known. Examples of the quaternary ammonium organic cation include dialkylimidazoles
Trialkyl imidazoles
Isoimidazoles
Ions, tetraalkylammonium ions, alkylpyridines
Ionic pyrazoles
Ionic, pyrrolidine
Ions, piperidines
Ions, and the like. Particular preference is given to imidazoles
Ions.
Examples of the tetraalkylammonium ion include, but are not limited to, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetrapentylammonium ion, triethylmethylammonium ion, and the like.
In addition, as alkyl pyridine
Examples of the ion include N-methylpyridine
Ionic, N-ethylpyridinesIonic, N-propylpyridinesIonic, N-butylpyridines
Ionic, 1-ethyl-2-methylpyridineIonic, 1-butyl-4-methylpyridine
Ionic, 1-butyl-2, 4-dimethylpyridine
Examples of the ions include, but are not limited to, these.
As imidazoles
Examples of the ion include 1, 3-dimethylimidazole
Ionic, 1-ethyl-3-methylimidazole
Ionic, 1-methyl-3-ethylimidazole
Ionic, 1-methyl-3-butylimidazole
Ionic, 1-butyl-3-methylimidazoleIonic, 1,2, 3-trimethylimidazole
Ionic, 1, 2-dimethyl-3-ethylimidazoleIonic, 1, 2-dimethyl-3-propylimidazoles
Ionic, 1-butyl-2, 3-dimethylimidazole
Examples of the ions include, but are not limited to, these.
Examples of the anion active species of the ambient temperature molten salt include halide ions such as chloride ions, bromide ions, and iodide ions; perchloric acid ion, thiocyanate ion, tetrafluoroboric acid ion, nitric acid ion, AsF6 -、PF6 -Inorganic acid ions, etc.; organic acid ions such as stearyl sulfonic acid ion, octyl sulfonic acid ion, dodecylbenzenesulfonic acid ion, naphthalenesulfonic acid ion, dodecylnaphthalenesulfonic acid ion, 7,8, 8-tetracyano-p-quinodimethane ion, and the like.
The ambient temperature molten salt may be used alone in 1 kind, or may be used in combination in 2 or more kinds.
Various additives may be used in the electrolyte solution as required. Examples of the additives include flame retardants, positive electrode surface treatment agents, negative electrode surface treatment agents, and overcharge inhibitors. Examples of the flame retardant and the flame retardant include halogenated compounds such as brominated epoxy compounds, phosphazene compounds, tetrabromobisphenol a, and chlorinated paraffins; antimony trioxide, antimony pentoxide, aluminum hydroxide, magnesium hydroxide, phosphate, polyphosphate, zinc borate and the like. Examples of the positive electrode surface treatment agent include carbon and metal oxides (MgO and ZrO)2Etc.) and organic compounds such as o-terphenyl. Examples of the negative electrode surface treatment agent include: vinylene carbonate (vinylene carbonate), fluoroethylene carbonate (fluoroethylene carbonate), polyethylene glycol dimethyl ether, and the like. Examples of the overcharge inhibitor include biphenyl and 1- (p-tolyl) adamantane.
The method for producing the power storage device of the present invention is not particularly limited, and the power storage device can be produced by a known method using a positive electrode, a negative electrode, an electrolyte solution, and if necessary, a separator. For example, in the case of a button type, a positive electrode, a separator as needed, and a negative electrode are inserted into an outer can. And an electrolyte is added thereto for impregnation. Then, the sealing body is sealed and caulked (here, "caulked" is originally "カシメる" in japanese) by joining the sealing body and tab welding (tabwelding) or the like, thereby obtaining the power storage device. The shape of the power storage device is not limited, and button type, cylinder type, flat type, and the like can be given.
The separator is a member for preventing short-circuiting in the battery due to direct contact between the positive electrode and the negative electrode, and a known material can be used. Specific examples of the separator include a porous polymer film such as polyolefin, and paper. The porous polymer film is preferably a film of polyethylene, polypropylene or the like, which is less affected by the electrolyte.
Examples
Specific modes for carrying out the present invention will be described below with reference to examples. However, the present invention is not limited to the following examples as long as the invention does not depart from the gist thereof.
In this example, an electrode was produced, and an electrode adhesion test was performed as an electrode evaluation by the following experiment.
[ evaluation of physical Properties of the produced electrode ]
As physical property evaluation of the produced electrode, an adhesion test was performed. The evaluation results are summarized and shown in table 1.
< adhesion test >
(measurement device)
Peel strength testing machine: STROGRAPH E3-L (Toyo Seiki Kagaku K.K.)
(method of adhesion test)
The adhesion test was performed by a 180 ° peel test. Specifically, the electrode was cut to a width of 2cm × a length of 5cm, a tape (adhesive tape: Nichiban Co., Ltd., width of 1.8cm, length of 5cm) was attached, and the tape was peeled off in a 180 ℃ direction at a test speed of 50mm/min and a load range (range) of 5N in a state where one end of the electrode in the longitudinal direction was fixed to STROGRAPH E3-L. The test was conducted 3 times, and the weighted average was obtained.
< measurement of average particle diameter >
The average particle diameter of the polymer was measured under the following conditions.
(measurement device)
Particle size distribution measuring apparatus using dynamic light scattering: zetasizer Nano (Spectris corporation) (measurement conditions)
1. The synthesized emulsion solution was sampled at 50. mu.L.
2. To the sampled emulsion solution, 700. mu.L of ion-exchanged water was added 3 times to dilute the solution.
3. 2100. mu.L of liquid was extracted from the dilution.
4. The remaining 50. mu.L of the sample was diluted with 700. mu.L of ion-exchanged water and measured.
[ Synthesis example 1]
89.20 parts by mass of n-butyl acrylate, 1.55 parts by mass of acrylic acid, 4.4 parts by mass of methacrylic acid, 4.15 parts by mass of polyethylene glycol monomethacrylate (manufactured by Nissan oil: BLEMER PE-90), 0.70 parts by mass of trimethylolpropane triacrylate (manufactured by Nongmura chemical Co., Ltd.: A-TMPT), 1 part by mass of sodium lauryl sulfate as an emulsifier, 50.00 parts by mass of ion-exchanged water, and 0.12 parts by mass of ammonium persulfate as a polymerization initiator were added to a beaker, and sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.5 to 8.0 using a 28% aqueous ammonia solution, to obtain a binder composition a (polymerization conversion rate 99% or more, solid content concentration 39.8 wt%) as an emulsion solution. The average particle diameter of the resulting polymer was 0.273. mu.m. The amounts of monomers used for the synthesis of the polymers are shown in table 1.
[ Synthesis example 2] of
72.34 parts by mass of n-butyl acrylate, 17.43 parts by mass of 2-ethylhexyl acrylate, 1.46 parts by mass of acrylic acid, 4.17 parts by mass of methacrylic acid, 3.93 parts by mass of polyethylene glycol monomethacrylate (manufactured by Nissan oil: BLEMER PE-90), 0.67 parts by mass of trimethylolpropane triacrylate (manufactured by Xinzhongcun chemical Co., Ltd.: A-TMPT), 1 part by mass of sodium dodecyl sulfate as an emulsifier, 50.00 parts by mass of ion exchange water, and 0.12 parts by mass of ammonium persulfate as a polymerization initiator were added to a beaker, and sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.6 to 8.0 using a 28% aqueous ammonia solution, to obtain a binder composition B (polymerization conversion rate 99% or more, solid content concentration 40 wt%) as an emulsion solution. The average particle size of the resulting polymer was 0.237. mu.m. The amounts of monomers used for the synthesis of the polymers are shown in table 1.
[ Synthesis example 3] of
Into a beaker, 54.42 parts by mass of n-butyl acrylate, 35.96 parts by mass of 2-ethylhexyl acrylate, 1.38 parts by mass of acrylic acid, 3.92 parts by mass of methacrylic acid, 3.70 parts by mass of polyethylene glycol monomethacrylate (manufactured by Nichigan: BLEMER PE-90), 0.62 part by mass of trimethylolpropane triacrylate (manufactured by Ninghamun chemical Co., Ltd.: A-TMPT), 1 part by mass of sodium lauryl sulfate as an emulsifier, 50.00 parts by mass of ion exchange water, and 0.12 part by mass of ammonium persulfate as a polymerization initiator were added, and the mixture was sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.5 to 7.8 using a 28% aqueous ammonia solution, to obtain binder composition C (polymerization conversion rate 98% or more, solid content concentration 39 wt%) as an emulsion solution. The average particle size of the resulting polymer was 0.225. mu.m. The amounts of monomers used for the synthesis of the polymers are shown in table 1.
[ Synthesis example 4]
82.59 parts by mass of n-butyl acrylate, 1.52 parts by mass of acrylic acid, 4.32 parts by mass of methacrylic acid, 10.88 parts by mass of polyethylene glycol monomethacrylate (manufactured by Nissan oil: BLEMER PE-90), 0.69 part by mass of trimethylolpropane triacrylate (manufactured by Nongmura chemical Co., Ltd.: A-TMPT), 1 part by mass of sodium lauryl sulfate as an emulsifier, 50.00 parts by mass of ion-exchanged water, and 0.12 part by mass of ammonium persulfate as a polymerization initiator were added to a beaker, and sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.4 to 7.8 using a 28% aqueous ammonia solution, to obtain a binder composition D (polymerization conversion rate 98% or more, solid content concentration 39 wt%) as an emulsion solution. The average particle size of the resulting polymer was 0.230. mu.m.
[ comparative Synthesis example 1]
89.86 parts by mass of n-butyl acrylate, 1.55 parts by mass of acrylic acid, 4.42 parts by mass of methacrylic acid, 4.17 parts by mass of polyethylene glycol monomethacrylate (made by daily oil: BLEMER PE-90), 1 part by mass of sodium lauryl sulfate as an emulsifier, 50.00 parts by mass of ion exchange water, and 0.12 part by mass of ammonium persulfate as a polymerization initiator were added to a beaker, and sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.6 to 7.8 using a 28% aqueous ammonia solution, to obtain a binder composition E (polymerization conversion rate 99% or more, solid content concentration 39 wt%) as an emulsion solution. The average particle diameter of the obtained polymer was 0.240. mu.m. The amounts of monomers used for the synthesis of the polymers are shown in table 1.
[ comparative Synthesis example 2]
43.35 parts by mass of n-butyl acrylate, 28.10 parts by mass of 2-ethylhexyl acrylate, 1.29 parts by mass of acrylic acid, 5.50 parts by mass of methacrylic acid, 6.92 parts by mass of polyethylene glycol monomethacrylate (manufactured by Nissan oil: BLEMER PE-90), 14.87 parts by mass of trimethylolpropane triacrylate (manufactured by Xinzhongcun chemical Co., Ltd.: A-TMPT), 1 part by mass of sodium lauryl sulfate as an emulsifier, 2 parts by mass of polyoxyalkylene alkenyl ether ammonium sulfate (manufactured by Kao corporation: Latemul PD-104), 50.00 parts by mass of ion exchange water, and 0.12 part by mass of ammonium persulfate as a polymerization initiator were added to a beaker, and the mixture was sufficiently stirred by an ultrasonic homogenizer to prepare an emulsion. The stirred reaction vessel was heated to 55 ℃ under a nitrogen atmosphere and the emulsion was added over 2 hours. After the addition of the emulsion, polymerization was carried out for another 1 hour, followed by cooling. After cooling, the pH of the polymerization solution was adjusted from 2.6 to 8.0 using a 28% aqueous ammonia solution, to obtain a binder composition F (polymerization conversion rate 99% or more, solid content concentration 39 wt%) as an emulsion solution. The average particle size of the resulting polymer was 0.205. mu.m. The amounts of monomers used for the synthesis of the polymers are shown in table 1.
[ Table 1]
< example of production of electrode >
[ example 1 for producing an electrode ]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition a obtained in synthesis example 1 of the binder composition, as solid contents, were added, and water was further added so that the solid content concentration of the slurry became 72% by mass, and the mixture was sufficiently mixed by a planetary mill to obtain a positive electrode slurry.
The obtained slurry for a positive electrode was applied to an aluminum current collector having a thickness of 20 μm using a 100 μm-gap Baker type applicator, dried at 110 ℃ for 12 hours or more in a vacuum state, and then pressed by a roll press machine to produce a positive electrode having a thickness of 36 μm and an electrode material density of 3.5 g/cc. The evaluation results of the adhesion test are shown in example 1 of table 1.
[ example for producing electrode 2]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition B obtained in synthesis example 2 of the binder composition, as solid contents, were added, and water was further added so that the solid content concentration of the slurry became 72% by mass, and the mixture was thoroughly mixed with a planetary mill to obtain a positive electrode slurry. Except for this, a positive electrode was produced in the same manner as in example 1. The thickness of the obtained positive electrode was 43 μm, and the density of the electrode material was 3.5 g/cc. The evaluation results of the adhesion test are shown in example 2 of table 1.
[ example 3 for producing an electrode ]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition C obtained in synthesis example 3 of the binder composition, in terms of solid content, were added water so that the solid content concentration of the slurry became 72% by mass, and the mixture was thoroughly mixed with a planetary mill to obtain a positive electrode slurry. Except for this, a positive electrode was produced in the same manner as in example 1. The thickness of the obtained positive electrode was 42 μm, and the density of the electrode material was 3.5 g/cc. The evaluation results of the adhesion test are shown in example 3 of table 1.
[ example production example 4 of electrode ]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition D obtained in synthesis example 4 of the binder composition, as solid contents, were added, and water was further added so that the solid content concentration of the slurry became 72% by mass, followed by thorough mixing with a planetary mill to obtain a positive electrode slurry. Except for this, a positive electrode was produced in the same manner as in example 1. The thickness of the obtained positive electrode was 41 μm, and the density of the electrode material was 3.2 g/cc. The evaluation results of the adhesion test are shown in example 4 of table 1.
[ comparative preparation example 1 of electrode ]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition E obtained in comparative synthesis example 1 of a binder composition, in terms of solid content, were added water so that the solid content concentration of the slurry became 72% by mass, and the mixture was thoroughly mixed with a planetary mill to obtain a positive electrode slurry. Except for this, a positive electrode was produced in the same manner as in example 1. The thickness of the obtained positive electrode was 44 μm, and the density of the electrode material was 3.5 g/cc. The evaluation results of the adhesion test are shown in comparative example 1 of table 1.
[ comparative preparation example 2 of electrode ]
To 95 parts by mass of nickel-cobalt-lithium manganate as a positive electrode active material, 3 parts by mass of acetylene black as a conductive aid, 1 part by mass of carboxymethyl cellulose, and 1 part by mass of binder composition F obtained in comparative synthesis example 2 of the binder composition were added, and water was further added so that the solid content concentration of the slurry became 72% by mass, and the mixture was thoroughly mixed with a planetary mill to obtain a positive electrode slurry. Except for this, a positive electrode was produced in the same manner as in example 1. The thickness of the obtained positive electrode was 43 μm, and the density of the electrode material was 3.5 g/cc. The evaluation results of the adhesion test are shown in comparative example 2 of table 1.
The results of evaluating the physical properties of the electrodes of the examples and comparative examples are shown in table 1.
[ Table 2]
Industrial applicability of the invention
The binder for electrodes of the present invention has excellent adhesiveness and can be effectively used in electric storage devices such as storage batteries for household use and in vehicle-mounted applications such as electric vehicles and hybrid electric vehicles.
Claims (11)
1. An adhesive for an electrode, characterized in that,
the binder for an electrode contains a polymer,
the polymer comprises a structural unit (A) derived from a monomer having a hydroxyl group represented by the following general formula (1);
a structural unit (B) derived from a (meth) acrylate monomer having a structural unit (B-1), wherein the structural unit (B-1) is derived from a (meth) acrylate monomer having an alkyl group having 4 to 6 carbon atoms;
a structural unit (C) derived from a (meth) acrylic acid monomer; and
structural units (D) derived from 5-or less-functional polyfunctional (meth) acrylate monomers;
the polymer has 80 to 95 mass% of the structural unit (B) and 3.5 to 15 mass% of the structural unit (C),
in the formula (1), R1Is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30.
2. The binder for an electrode according to claim 1, wherein n in the general formula (1) is an integer of 4 to 20.
3. The binder for an electrode according to claim 1 or 2, wherein the 5-or less-functional polyfunctional (meth) acrylate monomer in the structural unit (D) is a compound represented by the following general formula (3),
in the formula (3), R11Each being the same or different and being a hydrogen atom or a methyl group, R12An organic group having 2 to 100 carbon atoms and a valence of 5 or less, and m is an integer of 5 or less.
4. The binder for an electrode according to any one of claims 1 to 3, wherein the 5-or-less-functional polyfunctional (meth) acrylate monomer in the structural unit (D) is a 3-to 5-functional (meth) acrylate.
5. The binder for an electrode according to any one of claims 1 to 4, wherein the binder for an electrode has 50 to 95 mass% of the structural unit (B-1).
6. The binder for an electrode according to any one of claims 1 to 5, wherein the binder for an electrode has 0.5 to 15 mass% of the structural unit (A).
7. The binder for an electrode according to any one of claims 1 to 6, wherein the binder for an electrode has 0.1 to 10 mass of the structural unit (D).
8. A binder composition for an electrode, comprising the binder for an electrode according to any one of claims 1 to 7.
9. An electrode material comprising the binder for an electrode according to any one of claims 1 to 7.
10. An electrode comprising the binder for an electrode according to any one of claims 1 to 7 and an active material.
11. An electricity storage device comprising the electrode according to claim 8.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017141020 | 2017-07-20 | ||
| JP2017-141020 | 2017-07-20 | ||
| PCT/JP2018/027303 WO2019017479A1 (en) | 2017-07-20 | 2018-07-20 | Binder for electrode, binder composition for electrode, electrode material, electrode and power storage device |
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| CN110832683A true CN110832683A (en) | 2020-02-21 |
| CN110832683B CN110832683B (en) | 2023-03-14 |
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| Country | Link |
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| JP (1) | JP7215420B2 (en) |
| CN (1) | CN110832683B (en) |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112467133A (en) * | 2020-03-30 | 2021-03-09 | 万向一二三股份公司 | Lithium ion battery cathode slurry and preparation method thereof |
| CN114342124A (en) * | 2020-06-17 | 2022-04-12 | 广东省皓智科技有限公司 | Binder composition for secondary battery |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102473921A (en) * | 2009-08-07 | 2012-05-23 | Jsr株式会社 | Electrochemical device and binder composition |
| WO2017086215A1 (en) * | 2015-11-19 | 2017-05-26 | 旭化成株式会社 | Binder for electricity storage device and binder composition for electricity storage device |
| WO2017110901A1 (en) * | 2015-12-21 | 2017-06-29 | 株式会社大阪ソーダ | Binder for battery electrode, electrode, and battery |
-
2018
- 2018-07-20 CN CN201880044362.7A patent/CN110832683B/en active Active
- 2018-07-20 WO PCT/JP2018/027303 patent/WO2019017479A1/en active Application Filing
- 2018-07-20 JP JP2019530618A patent/JP7215420B2/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102473921A (en) * | 2009-08-07 | 2012-05-23 | Jsr株式会社 | Electrochemical device and binder composition |
| WO2017086215A1 (en) * | 2015-11-19 | 2017-05-26 | 旭化成株式会社 | Binder for electricity storage device and binder composition for electricity storage device |
| WO2017110901A1 (en) * | 2015-12-21 | 2017-06-29 | 株式会社大阪ソーダ | Binder for battery electrode, electrode, and battery |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112467133A (en) * | 2020-03-30 | 2021-03-09 | 万向一二三股份公司 | Lithium ion battery cathode slurry and preparation method thereof |
| CN114342124A (en) * | 2020-06-17 | 2022-04-12 | 广东省皓智科技有限公司 | Binder composition for secondary battery |
| CN114342124B (en) * | 2020-06-17 | 2024-04-09 | 广东省皓智科技有限公司 | Binder composition for secondary battery |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110832683B (en) | 2023-03-14 |
| JPWO2019017479A1 (en) | 2020-07-30 |
| WO2019017479A1 (en) | 2019-01-24 |
| JP7215420B2 (en) | 2023-01-31 |
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