JP2015064972A - Binder resin for secondary battery electrode, slurry for secondary battery electrode using the same, secondary battery electrode and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder resin for a secondary battery electrode, capable of providing a secondary battery electrode excellent in flexibility, and further capable of providing a secondary battery excellent in battery characteristics.SOLUTION: A binder resin for a secondary battery electrode contains a polymer (A) including a vinyl cyanide unit, and a polyolefin resin (B) and/or a paraffin resin (C). The binder resin for a secondary battery electrode can be obtained by polymerizing a monomer (a) including a vinyl cyanide unit under the presence of a polyolefin resin (B) and/or a paraffin resin (C).

Description

  The present invention relates to a secondary battery electrode slurry composition comprising a secondary battery binder resin and active material particles, a secondary battery electrode produced using the slurry composition, and a secondary battery comprising the electrode. .

In recent years, lithium ion secondary batteries are used in portable devices such as mobile phones, video cameras, and notebook computers, hybrid vehicles, and electric vehicles. An electrode for a lithium ion secondary battery is usually obtained by mixing a solvent in a mixture obtained by adding an appropriate amount of a binder to an electrode active material, applying it to a paste, applying it to a current collector, drying it and then pressing it. . As a binder, polyvinylidene fluoride (hereinafter abbreviated as “PVDF”) is used as a material satisfying solvent resistance to an organic solvent used in an electrolytic solution, oxidation resistance within a driving voltage, reduction resistance, and the like. Is used. However, PVDF has a problem of low adhesion to the current collector.
As a method for improving the low adhesion of PVDF, a proposal using a (meth) acrylonitrile polymer has been made. For example, in the prior art documents 1 and 2, an acrylonitrile polymer is used as a binder to improve the adhesion and adhesion to the current collector.
In addition, when using a battery, there is a concern that a temperature increase may occur in the battery due to a short circuit or the like, which may cause a fire or a device failure. However, as described in Reference 3, a wax component is added to the electrode. Thus, a method for improving the safety of the battery has been proposed. In this invention, the wax component quickly reacts to the temperature rise in the battery and melts, thereby interrupting the current in the electrode and preventing the temperature inside the battery from significantly increasing due to excessive current flow. It is.

WO02 / 039518 JP2010-174058 Special table 2009-522719

  However, in the prior art document 1, the amount of acrylonitrile occupying the total amount of the binder is small, and the good adhesion to the current collector of the (meth) acrylonitrile polymer cannot be fully exhibited.

Prior Document 2 proposes an electrode binder mainly composed of an acrylonitrile polymer. However, when the (meth) acrylonitrile polymer is the main component, the produced electrode is inferior in flexibility, and the mixture layer is cracked and cracked in the winding process in the production process, making it difficult to produce a battery. It was assumed that
Prior document 3 proposes a method of adding a wax component to an electrode using PVDF as a binder in order to improve battery safety. However, the addition of a wax component to PVDF, which has a low adhesion with the current collector, further reduces the adhesion with the current collector, and the current collector and the mixture layer are peeled off during production. There is a concern that it will.

  As a result of intensive investigations in view of the above-described problems and consideration thereof, the present inventor includes a vinyl cyanide unit by using a polymer containing a vinyl cyanide unit and a binder containing an olefin resin and / or a paraffin resin. It was found that an electrode provided with flexibility by an olefin resin and / or a paraffin resin can be produced while maintaining excellent adhesion to the current collector of the polymer.

The present invention relates to the following.
[1] Binder resin for secondary battery electrode containing polymer (A) containing vinyl cyanide unit and olefin resin (B) and / or paraffin resin (C) [2] Olefin resin (B) and / or paraffin The binder resin for secondary battery electrodes [3], obtained by polymerizing the monomer (a) containing a vinyl cyanide unit in the presence of the resin (C), includes two polyolefin resins (B). The binder resin for secondary battery electrodes according to [1] or [2], which does not have a heavy bond [4] A secondary battery comprising the binder resin according to any one of [1] to [3]. Electrode binder resin composition [5] An electrode slurry comprising the binder resin according to any one of [1] to [3], an active material, and a solvent.
[6] An electrode slurry containing the binder resin composition for a secondary battery electrode according to [4], an active material, and a solvent.
[7] A current collector, and a mixture layer provided on the current collector,
The electrode for secondary batteries in which the said mixture layer contains the binder resin composition for secondary battery electrodes as described in said [4].
[8] A lithium ion secondary battery comprising the secondary battery electrode according to [7].

  ADVANTAGE OF THE INVENTION According to this invention, the binder resin for secondary battery electrodes with favorable electrode flexibility, the binder resin composition for secondary battery electrodes, electrode slurry, the electrode for secondary batteries, and a lithium ion secondary battery can be provided.

  Hereinafter, the present invention will be described in detail.

<Binder resin for secondary battery electrode>
The binder resin for secondary battery electrodes used in the present invention is characterized by containing a polymer (A) containing a vinyl cyanide unit and an olefin resin (B) and / or a paraffin resin (C).

<Polymer (A) containing vinyl cyanide unit>
Although there is no restriction | limiting in particular as a vinyl cyanide monomer (a) used as the structural unit of the polymer (A) containing a vinyl cyanide unit, For example, acrylic-type nitrile group containing monomers, such as acrylonitrile and methacrylonitrile , A cyan nitrile group-containing monomer such as α-cyanoacrylate and dicyanovinylidene, a fumaric nitrile group-containing monomer such as fumaronitrile, and the like can be used. Among these, (meth) acrylonitrile is preferable from the viewpoint of easy polymerization and cost performance.
These vinyl cyanide monomers (a) can be used alone or in combination of two or more.

The content of the vinyl cyanide monomer (a) is preferably 50% by mass or more, more preferably 70% by mass, based on all monomers forming the polymer (A) containing vinyl cyanide units. As mentioned above, More preferably, it is 80 mass% or more. When the content of the vinyl cyanide monomer (a) is 50% by mass or more, the adhesiveness with the current collector expected for the polymer (A) containing vinyl cyanide units can be sufficiently exhibited. I can do it.
Moreover, the polymer (A) containing a vinyl cyanide unit can contain monomers other than the vinyl cyanide monomer (a) as a constituent unit. Other monomers are not particularly limited. For example, short-chain (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, etc. Body; long chain (meth) acrylic acid ester monomers such as stearyl (meth) acrylate and lauryl (meth) acrylate; carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid and crotonic acid and salts thereof; Vinyl halide monomers such as vinyl chloride, vinyl bromide and vinylidene chloride; maleimides such as maleic imide and phenylmaleimide; aromatic vinyl monomers such as styrene and α-methylstyrene; (meth) allylsulfonic acid Sodium, sodium (meth) allyloxybenzenesulfonate, stille Sodium sulfonate, 2-acrylamido-2-methylpropane sulfonic acid group-containing vinyl monomers and salts thereof such as sulfonic acid; (meth) acrylamide, and vinyl acetate.
These other monomers can be used alone or in combination of two or more. Moreover, you may form the polymer in which the polymer (A) containing a vinyl cyanide unit is copolymerized with the olefin resin (B) and the paraffin resin (C).
The polymer (A) containing vinyl cyanide units is 50% by mass when the total of the polymer (A) containing vinyl cyanide units and the polyolefin resin (B) and / or paraffin resin (C) is 100% by mass. It is preferable that it is 99 mass% or less, More preferably, it is 70 mass% or more and 97 mass% or less, More preferably, it is 80 mass% or more and 95 mass% or less. When the content of the polymer (A) containing vinyl cyanide units is 50% by mass or more, a current collector that is expected to exhibit the polymer (A) containing vinyl cyanide units in the mixture layer; It is possible to sufficiently exhibit the adhesiveness. When the content of the polymer (A) containing vinyl cyanide units is 99% by mass or less, the produced electrode can sufficiently exhibit flexibility.

<Olefin resin (B), paraffin resin (C)>
The olefin resin (B) used in the present invention is an alkene polymer and is represented by CnH2n + 2. The olefin resin (B) is not particularly limited, and it is possible to use polyethylene, polypropylene, polybutene, polybutadiene, polyisoprene, or an olefin resin in which some hydrocarbon groups are modified with functional groups.
Among these, as the olefin resin (B), those having no double bond in the structure are preferable. Examples of the olefin resin (B) not containing a double bond include polyethylene, polypropylene, and polybutene.
By using what does not contain a double bond as an olefin resin (B), the binder resin of this invention can be made excellent in the oxidation resistance in a battery. Moreover, when manufacturing the polymer (A) containing a vinyl cyanide unit by suspension polymerization, it is preferable to use latex as the olefin resin (B).
Paraffin resin (C) is represented by CnH2n. Examples of the paraffin resin (C) include liquid paraffin, paraffin wax, and paraffin resin in which some hydrocarbon groups are modified with functional groups.
The olefin resin (B) and the paraffin resin (C) are 1 to 2 when the total of the polymer (A) and the polyolefin resin (B) and / or the paraffin resin (C) containing vinyl cyanide units is 100% by mass. It is preferable that it is 50 mass%, More preferably, it is 3-30 mass%, More preferably, it is 5-20 mass%. When the content of the olefin resin (B) and the paraffin resin (C) is 1% by mass or more, the produced electrode can sufficiently exhibit the flexibility. Moreover, when content of an olefin resin (B) and paraffin resin (C) is 50 mass% or less, the adhesiveness of a mixture layer and current collection foil can fully be exhibited.

<Method for producing binder resin>
The binder resin of the present invention can also be obtained by a method of polymerizing a monomer (a) containing a vinyl cyanide monomer in the presence of an olefin resin (B) and / or a paraffin resin (C). Specifically, it is obtained by dropping a monomer (a) containing a vinyl cyanide monomer in water in which an olefin resin (B) and / or a paraffin resin (C) is dispersed and performing suspension polymerization. I can do it.
The binder resin of the present invention can also be obtained by mixing a polymer (A) containing vinyl cyanide units obtained by polymerizing separately, an olefin resin (B) and / or a paraffin resin (C). I can do it.

<Polymerization initiator>
As a polymerization initiator used for suspension polymerization, a water-soluble polymerization initiator is preferable because of excellent polymerization initiation efficiency and the like.
Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; water-soluble peroxides such as hydrogen peroxide; 2,2′-azobis (2-methylpropionamidine) Water-soluble azo compounds such as dihydrochloride are exemplified.
An oxidizing agent such as persulfate is a redox initiator in combination with a reducing agent such as sodium hydrogen sulfite, ammonium hydrogen sulfite, sodium thiosulfate, hydrosulfite, and a polymerization accelerator such as sulfuric acid, iron sulfate, copper sulfate. Can also be used.
Of these, persulfates are preferred because the production of the copolymer is easy.

<Chain transfer agent>
In the suspension polymerization, a chain transfer agent can be used for the purpose of adjusting the molecular weight.
Examples of the chain transfer agent include mercaptan compounds, thioglycol, carbon tetrachloride, and α-methylstyrene dimer. Among these, α-methylstyrene dimer is preferable because it has little odor and is easy to handle.

<Solvent>
In suspension polymerization, a solvent other than water can be added to adjust the particle size of the resulting copolymer.
Examples of solvents other than water include amides such as NMP, N, N-dimethylacetamide, and N, N-dimethylformamide; N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea, tetramethylurea, and the like. Ureas; lactones such as γ-butyrolactone and γ-caprolactone; carbonates such as propylene carbonate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; methyl acetate, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, Esters such as butyl carbitol acetate, ethyl cellosolve acetate and ethyl carbitol acetate; Grimes such as diglyme, triglyme and tetraglyme; Hydrocarbons such as toluene, xylene and cyclohexane; Examples thereof include sulfoxides such as til sulfoxide; sulfones such as sulfolane; and alcohols such as methanol, isopropanol and n-butanol.
These solvents may be used alone or in combination of two or more.

<Surfactant>
When the polymer is produced by emulsion polymerization, a surfactant can be used.
Examples of the surfactant include anionic surfactants such as dodecyl sulfate and dodecyl benzene sulfonate; nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl ester; alkyltrimethylammonium salt and alkyl Examples thereof include cationic surfactants such as amines. Surfactant may be used individually by 1 type and may use 2 or more types together.

<Binder resin composition>
The binder resin composition for a secondary battery electrode of the present invention contains a polymer (A) containing a vinyl cyanide unit and a polyolefin resin (B) and / or a paraffin resin (C), but others that improve battery performance. Additives such as “binder” and “viscosity modifier” for improving coatability may be combined within a range not impairing the intended effect of the present invention.

  Other binders include, for example, polymers such as styrene-butadiene rubber, poly (meth) acrylonitrile, ethylene-vinyl alcohol copolymer, vinyl acetate polymer; fluorine-based heavy metals such as polyvinylidene fluoride, tetrafluoroethylene, and pentafluoropropylene. Coalescence is mentioned.

Examples of the viscosity modifier include cellulose polymers such as carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, and ammonium salts thereof; poly (meth) acrylates such as sodium poly (meth) acrylate; polyvinyl alcohol, polyethylene oxide , Polyvinylpyrrolidone, copolymer of acrylic acid or acrylate and vinyl alcohol, maleic anhydride, maleic acid or copolymer of fumaric acid and vinyl alcohol, modified polyvinyl alcohol, modified polyacrylic acid, polyethylene glycol, polycarboxylic acid Is mentioned.
The additive finally remaining on the electrode is preferably electrochemically stable.

  The binder resin for secondary battery electrodes may be used in any form of powder, a solution dissolved in a solvent, and an emulsion dispersed in an aqueous or oily medium.

<Use of binder resin>
Although the kind of battery which can use the binder resin for secondary batteries of this invention is not specifically limited, Use to the positive electrode or negative electrode in a non-aqueous secondary battery, especially a lithium ion secondary battery is especially preferable.

<Slurry composition for secondary battery electrode>
The slurry composition for secondary battery electrodes includes at least the above-described binder resin, electrode active material, and solvent. Further, it may contain a conductive additive and other additives. Specifically, the binder resin for secondary battery electrodes and the electrode active material of the present invention can be obtained by dispersing or dissolving them in a solvent together with a conductive additive and other additives.

  The composition of the slurry composition for secondary battery electrodes is 0.1 to 10 parts by weight of the binder resin for secondary battery electrodes of the present invention and 0.5 to 20 parts of the conductive auxiliary agent when the active material is 100 parts by weight. It is preferable to set it as a mass part. Moreover, you may add 0-10 mass parts of other additives.

<Electrode for secondary battery>
The electrode for a secondary battery has a current collector and a mixture layer provided on at least one surface of the current collector. The binder resin of this invention is used as a material which comprises this mixture layer. Specifically, a solid phase obtained by blending an active material with the binder resin for a secondary battery electrode of the present invention and drying or dissolving the slurry composition dissolved or dispersed in the solvent becomes the mixture layer.

The active material used for the mixture layer may be any material in which the potential of the positive electrode material and the potential of the negative electrode material are different.
In the case of a lithium ion secondary battery, examples of the positive electrode active material used include a lithium-containing metal composite oxide containing lithium and at least one metal selected from iron, cobalt, nickel, and manganese. A positive electrode active material may be used individually by 1 type, and may use 2 or more types together.
Examples of the negative electrode active material used include carbon materials such as graphite, amorphous carbon, carbon fiber, coke, and activated carbon; composites of the above carbon materials and metals such as silicon, tin, and silver, or oxides thereof. Things. A negative electrode active material may be used individually by 1 type, and may use 2 or more types together.

In the lithium ion secondary battery, it is preferable to use a lithium-containing metal composite oxide for the positive electrode and graphite for the negative electrode. By setting it as such a combination, the voltage of a lithium ion secondary battery will be about 4V.
In addition, you may use a positive electrode active material in combination with a conductive support agent.
Examples of the conductive assistant include graphite, carbon black, carbon nanotube, carbon nanofiber, acetylene black, ketjen black, and conductive polymer. These conductive auxiliary agents may be used individually by 1 type, and may use 2 or more types together.

The current collector may be any material having conductivity, and a metal can be used as the material. A metal that is difficult to alloy with lithium is desirable, and specific examples include aluminum, copper, nickel, iron, titanium, vanadium, chromium, manganese, and alloys thereof.
Examples of the shape of the current collector include a thin film shape, a net shape, and a fiber shape. Among these, a thin film is preferable. The thickness of the current collector is preferably 5 to 30 μm, more preferably 8 to 25 μm.

  The mixture layer is formed using a binder resin containing an electrode active material or the like. The mixture layer is obtained, for example, by preparing a slurry composition containing the binder resin, additive, solvent and electrode active material, applying the slurry composition to a current collector, and drying and removing the solvent.

Solvents used for preparing the slurry composition are, for example, water, N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylformamide, tetrahydrofuran, dimethylacetamide, dimethylsulfoxide, hexamethylsulfuramide, tetramethylurea, acetone , Methyl ethyl ketone, N-methylpyrrolidone and ester solvents (ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, etc.), N-methylpyrrolidone and glyme solvents (diglyme, triglyme, tetraglyme, etc.) A mixed solvent of the mixed solution may be used, and N-methylpyrrolidone is particularly preferable. These may be used alone or in combination of two or more.
Moreover, additives, such as a dispersing agent and a viscosity modifier, can be added to a slurry composition as needed. Specific examples include a rheology control agent that adjusts the viscosity of the slurry, a leveling agent that provides smoothness after application to the current collector, and a dispersant. Any of these can be used.

  As an example of a process for producing an electrode, the binder resin for a secondary battery electrode of the present invention, an electrode active material, and acetylene black are kneaded in the presence of a solvent such as N-methylpyrrolidone (NMP) to obtain a slurry. The slurry is applied to an electrode current collector, dried, and then pressed as necessary to obtain an electrode. The drying conditions are not particularly limited as long as the solvent can be sufficiently removed and the battery binder does not decompose, but heat treatment is performed at 40 to 160 ° C., preferably 60 to 140 ° C. for 1 minute to 10 hours. It is preferable. Within this range, the binder resin for the secondary battery can impart high adhesion between the active material and the current collector or the active material without being decomposed.

The negative electrode structure and the positive electrode structure manufactured as described above are disposed with a liquid-permeable separator (for example, a polyethylene or polypropylene porous film) interposed therebetween, and non-aqueous electrolysis is provided therewith. A non-aqueous secondary battery is formed by impregnating the liquid. It also has a structure obtained by winding a negative electrode structure / separator with active layers formed on both sides / a positive electrode structure / separator with active layers formed on both sides into a roll (spiral shape). A cylindrical secondary battery is obtained by housing in the bottom metal casing, connecting the negative electrode to the negative electrode terminal, connecting the positive electrode to the positive electrode terminal, impregnating the electrolyte, and sealing the casing.

For example, in the case of a lithium ion secondary battery, an electrolytic solution in which a lithium salt as an electrolyte is dissolved in a non-aqueous organic solvent at a concentration of about 1M is used.
As the lithium salt, examples of the electrolyte include LiClO4, LiBF4, LiI, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, LiCl, LiBr, LiB (C2H5) 4, LiCH3SO3, LiC4F9SO3, Li (CF3SO2) 2 Li [(CO2) 2] 2B is mentioned.
Nonaqueous organic solvents include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as γ-butyrolactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl Ethers such as ether, 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; acetonitrile, nitromethane, NMP Nitrogens such as methyl formate, methyl acetate, butyl acetate, methyl propionate, ethyl propionate, phosphoric acid triester; diglyme, triglyme, tetra Glymes such as lime; ketones such as acetone, diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone; sulfones such as sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propane sultone, 4-butane sultone, Examples include sultone such as naphtha sultone. One type of electrolytic solution may be used alone, or two or more types may be used in combination.

<Secondary battery>
The battery can be manufactured using a known method. For example, in the case of a lithium ion secondary battery, first, two electrodes, a positive electrode and a negative electrode, are wound through a separator made of a polyethylene microporous film. . The obtained spiral wound group is inserted into a battery can, and a tab terminal previously welded to a negative electrode current collector is welded to the bottom of the battery can. Inject the electrolyte into the resulting battery can, weld the tab terminal that was previously welded to the positive electrode current collector to the battery lid, and place the lid on the top of the battery can via an insulating gasket A battery is obtained by caulking and sealing the part where the lid and the battery can are in contact.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, a following example does not limit the scope of the present invention.

<Synthesis of binder resin for secondary battery electrode>
(Production Example 1)
MGP which is maleic anhydride-modified polypropylene latex as 881.7 g of distilled water, olefin resin (B) and paraffin resin (C) in a 2 liter separable flask equipped with a stirrer, thermometer, cooling pipe and nitrogen gas introduction pipe -055 (manufactured by Maruyoshi Kasei Co., Ltd.) was charged with 83.3 g (solid content: 25 g), and nitrogen gas was bubbled for 15 minutes at an air flow rate of 100 mL / min. The temperature was raised to 60 ° C. while stirring, and the nitrogen gas aeration was switched to the flow.
Subsequently, 0.65 g of ammonium persulfate, 0.22 g of 50% by mass ammonium hydrogen sulfite, 0.15 g of 0.1% by mass iron sulfate and 30 g of distilled water were added as polymerization initiators.
Acrylonitrile (75 g) as a monomer (a) containing a vinyl cyanide monomer was bubbled into a separable flask for 30 minutes after nitrogen gas was bubbled for 15 minutes. After finishing the enemy, the polymerization was completed by maintaining at 60 ° C. for 3 hours.
The stirring was stopped and the mixture was cooled, and the reaction solution was filtered with suction. After washing with warm water at 60 ° C., the resin was dried at 80 ° C. for 24 hours to obtain a binder resin 1.

(Production Example 2)
The same procedure as in Production Example 1 was conducted except that the olefin resin (B) and the paraffin resin (C) charged in the separable flask were changed to 83.3 g (solid content 25 g), which is polybutene latex, Emawet 200E (manufactured by NOF Corporation). Binder resin 2 was obtained.

(Production Example 3)
The amount of distilled water charged into the separable flask is 930 g, the olefin resin (B), the paraffin resin (C) is a paraffin wax latex MYW-20 (manufactured by Maruyoshi Chemical Co., Ltd.) 20 g (solid content 10 g) A binder resin 3 was obtained in the same manner as in Production Example 1 except that 90 g of acrylonitrile was used.
(Production Example 4)
A binder resin 4 was obtained in the same manner as in Production Example 1 except that the amount of distilled water charged into the separable flask was 940 g, the olefin resin (B) and the paraffin resin (C) were not added, and the dropping acrylonitrile was 100 g.

It shows in Table 1-a about the composition of binder resin 1-4.

Example 1
The characteristics of the slurry composition for electrodes using the binder resin 1 as a binder resin were evaluated.
<Preparation of slurry for battery electrode>
As an electrode composition, lithium cobalt oxide (manufactured by Nippon Chemical Industry Co., Ltd., product name: Cellseed C-5H), acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product name: Denka Black), polymer (C-1) The mixture was mixed at a mass ratio of 100: 5: 2 and kneaded using N-methylpyrrolidone as a solvent so as to be so-called solidified. For the kneading, an auto-revolving mixer (Awatori Nerita ARV-200, manufactured by Shinky Corporation) was used. Further, N-methylpyrrolidone was added and kneaded, and the solid content was lowered so that the viscosity could be applied. Thus, a final battery electrode slurry was obtained.

<Creation of electrode>
The slurry prepared above was applied to a current collector using a doctor blade. The set thickness of the doctor blade was 220 μm, and the current collector used was an aluminum foil (thickness 20 μm). The current collector coated with the slurry was dried at 80 ° C. for 50 minutes to obtain an electrode having a basis weight of 21 mg / cm 2.
<Evaluation of electrode flexibility>
The electrode was cut into a width of 3 cm and a length of 5 cm to obtain a test piece 1. Subsequently, a mandrel (diameters of 16 mm, 10 mm, 5 mm, 3 mm, and 2 mm, respectively) was applied to the aluminum foil surface of the test piece 1, and one side of the test piece 1 was fixed with tape. The state of the mixture layer when the test piece 1 was bent so that the aluminum foil surface was inside was visually observed, and the flexibility of the electrode was evaluated according to the following evaluation criteria.
○: No change.
Δ: Horizontal streak entered.
X: Cracks or peeling occurred.

(Examples 2 and 3)
An electrode was prepared in the same manner as in Example 1 except that the binder resins 2 and 3 were used as the battery electrode binder resin, and the flexibility was evaluated.

It shows in Table 2 about the evaluation result of Examples 1-3.

Example 4
The binder resin 4 produced in Production Example 4, the olefin resin (B), and paraffin resin (C) embewet 200E (manufactured by NOF Corporation) as a solid content ratio is 90:10. Mixed and dissolved in N-methylpyrrolidone. The dope of N-methylpyrrolidone obtained after mixing and dissolution was degassed in an evaporator to remove contained water.
N-methylpyrrolidone dope of binder resin 5 was obtained by the above operation.

<Preparation of slurry for battery electrode>
The dope of N-methylpyrrolidone after removing the water was lithium cobalt oxide (manufactured by Nippon Chemical Industry Co., Ltd., product name: Cellseed C-5H), acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.), as an electrode composition. Product name: Denka Black) and binder resin 5 were mixed and kneaded so that the mass ratio was 100: 5: 2. Further, N-methylpyrrolidone was added and kneaded, and the solid content was lowered so that the viscosity could be applied. Thus, a final battery electrode slurry was obtained.

<Creation of electrode>
The slurry prepared above was applied and dried in the same manner as in Example 1 to obtain an electrode.
<Evaluation of electrode flexibility>
The obtained electrode was subjected to a flexibility test under the same conditions as in Example 1 to evaluate the flexibility.

(Example 5)
Binder resin in the same manner as in Example 4 except that olefin resin (B) and paraffin resin (C) mixed with binder resin 4 are paraffin latex MYW-20 (manufactured by Maruyoshi Chemical Co., Ltd.). An electrode was prepared by obtaining a dope of 6 and evaluated for flexibility.

The compositions of Examples 4 and 5 are shown in Table 1-b.

(Comparative Example 1)
An electrode was prepared in the same manner as in Example 1 except that the binder resin 4 was used as the binder resin, and the flexibility was evaluated.

The evaluation results of Examples 4 and 5 and Comparative Example 1 are shown in Table 2.

Claims (8)

Binder resin for secondary battery electrode containing polymer (A) containing vinyl cyanide unit, and polyolefin resin (B) and / or paraffin resin (C). The binder resin for secondary battery electrodes according to claim 1, obtained by polymerizing the monomer (a) containing a vinyl cyanide unit in the presence of the polyolefin resin (B) and / or the paraffin resin (C). The binder resin for secondary battery electrodes according to claim 1 or 2, wherein the polyolefin resin (B) does not have a double bond. The binder resin composition for secondary battery electrodes containing the binder resin as described in any one of Claims 1-3.   The electrode slurry containing the binder resin as described in any one of Claims 1-3, or the binder resin composition for secondary battery electrodes of Claim 4, an active material, and a solvent. The electrode slurry containing the binder resin composition for secondary battery electrodes of Claim 4, an active material, and a solvent. A current collector, and a mixture layer provided on the current collector,
The electrode for secondary batteries in which the said mixture layer contains the binder resin composition for secondary battery electrodes of Claim 4.   A lithium ion secondary battery comprising the secondary battery electrode according to claim 7.