JP2002141068A - Binder for forming nonaqueous battery electrode, electrode composite agent, electrode structure and nonaqueous battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for forming a nonaqueous battery electrode fit for making an electrode with good anti-solvent property against nonaqueous electrolyte and a good adhesive property with a collector. SOLUTION: The binder for forming a nonaqueous battery electrode comprises a fluorine-containing block co-polymer composed of a fluorine- containing system polymer segment formed from a fluorine-containing system monomer and a non-fluorine-containing system polymer segment formed from a non-fluorine system monomer. The fluorine-containing system polymer segment is preferably to be formed either from of a single fluorine-containing monomer or a mixture of a fluorine-containing monomer and alkyl(meta)acrylate with the number of alkyl group carbons of 12 to 22. An electrode mixture is obtained by combining powder electrode materials with this binder for forming the nonaqueous battery electrode. The electrode structure is composed by forming an electrode mixture layer on at least one face of a strip collector. Either a cathode or an anode of the nonaqueous battery is structured with an electrode structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous battery, and more particularly, to a non-aqueous electrolyte which is a solvent for an electrolyte in a non-aqueous electrochemical device of a lithium ion battery, and has a good adhesion to a current collector. The present invention relates to a non-aqueous battery electrode binder suitable for forming an electrode having the following, an electrode mixture formed using the binder, an electrode structure, and a non-aqueous battery.

[0002]

2. Description of the Related Art In recent years, along with the reduction in size and weight of electronic devices,
The demand for a smaller and lighter battery as the power source has been increasing. In order to obtain more energy with less capacity and weight, a higher voltage per battery is required. From this finding, a nonaqueous battery using a carbonaceous material capable of storing lithium or lithium ions as a negative electrode active material and using lithium cobalt oxide or the like as a positive electrode active material has recently been receiving attention.

[0003] In such non-aqueous batteries, ethylene tetrafluoride polymer, styrene-butadiene copolymer, and the like have been used as a binder for an electrode active material. A lithium ion secondary battery using a vinylidene fluoride polymer having good formability as a binder has been put to practical use.

However, since the vinylidene fluoride-based polymer has a relatively weak adhesive force with the electrode active material and the current collector, a phenomenon of the electrode active material falling off and the electrode mixture being separated from the current collector during use. Was seen. For this reason, the discharge capacity of the battery may be significantly reduced during long-term use, which is a practical problem.

In order to solve this problem, a silane-modified vinylidene fluoride polymer (JP-A-6-93025) and a vinylidene fluoride polymer containing a carboxyl group or a carbonate group (JP-A-6-172452) have been proposed. And modified vinylidene fluoride polymers having a carboxyl group or an epoxy group (JP-A-9-32067).

[0006]

However, the above-mentioned various modified vinylidene fluoride-based polymers are basically random copolymers, and can only function as a random copolymer. Adhesion with electric bodies and the like was not yet satisfactory. In addition, the modified vinylidene fluoride-based polymer is impaired in solvent resistance, which is a property of vinylidene fluoride, because it is modified,
Compared with the conventional vinylidene fluoride-based polymer, there is a problem that the solvent resistance to the nonaqueous electrolyte is insufficient and the degree of swelling is increased.

Accordingly, a main object of the present invention is to form a non-aqueous battery electrode suitable for forming an electrode having good solvent resistance to a non-aqueous electrolyte and good adhesion to a current collector. To provide a binder for use.

Still another object of the present invention is to provide an electrode mixture, an electrode structure and a non-aqueous battery having good characteristics using the above-mentioned binder for forming a non-aqueous battery electrode.

[0009]

Means for Solving the Problems In order to achieve the above object, a binder for forming a non-aqueous battery electrode according to the first aspect of the present invention comprises:
It is composed of a fluorinated block copolymer composed of a fluorinated polymer segment formed from a fluorinated monomer and a non-fluorinated polymer segment formed from a non-fluorinated monomer. .

The binder for forming a non-aqueous battery electrode according to the second invention is the binder according to the first invention, wherein the fluorinated polymer segment comprises a fluorinated monomer alone or a fluorinated monomer, It is formed from a mixture with an alkyl (meth) acrylate having 12 to 22 carbon atoms.

[0011] The binder for forming a non-aqueous battery electrode according to the third invention is the binder according to the second invention, wherein the fluorine-containing monomer is
It is one or more of the monomers represented by the following general formula (A).

[0012]

Embedded image (Rf is a fluoroalkyl group or fluoroalkenyl group having 3 to 21 carbon atoms, R ¹ is an alkylene group having 1 to 10 carbon atoms, and R ² is hydrogen or a methyl group.) The electrode mixture of the fourth invention is: The powdered electrode material is bonded with the binder for forming a non-aqueous battery electrode according to any one of the first to third inventions.

An electrode structure according to a fifth aspect of the present invention is obtained by forming a layer of the electrode mixture according to the fourth aspect of the present invention on at least one surface of a plate-shaped current collector. A nonaqueous battery according to a sixth invention is a nonaqueous battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode is the electrode according to the fifth invention. It is a structure.

[0014]

Embodiments of the present invention will be described below in detail. The binder for forming a non-aqueous battery electrode of the present invention comprises a fluorinated block copolymer composed of a fluorinated polymer segment and a non-fluorinated polymer segment. The fluorinated polymer segment shows good solvent resistance to the non-aqueous electrolyte, and the non-fluorinated polymer segment shows good adhesion to the current collector made of a metal material.

First, the fluorine-containing polymer segment will be described. The fluorinated polymer segment is composed of a polymer formed from a fluorinated monomer. Above all, those formed from a single fluorine-containing monomer or a mixture of a fluorine-containing monomer and an alkyl (meth) acrylate having an alkyl chain length of 12 to 22 carbon atoms are preferable for the non-aqueous electrolyte. It is preferable for exhibiting solvent resistance.

As the fluorine-containing monomer, one or more of all known fluorine-containing monomers can be used. For example, the fluorine-containing monomers described in the following general formulas (A) to (G) are exemplified.

[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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[0023]

Embedded image Specific examples of the general formula (A) include the following (a-1) to (a-1).
And the monomer 2). _{F (CF 2) 6 (CH} 2) 2 OCOCH = CH 2 (a-1) F (CF 2) 8 (CH 2) 2 OCOCH = CH 2 (a-2) F (CF 2) 10 (CH 2) ₂ OCOCH = CH ₂ (a-3) H (CF ₂ ) ₈ CH ₂ OCOCH = CH ₂ (a-4) (CF ₃ ) ₂ CF (CF ₂ ) ₆ (CH ₂ ) ₂ OCOCH = CH ₂ (a- 5) (CF ₃ ) ₂ CF (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH = CH ₂ (a-6) F (CF ₂ ) ₆ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ (a-7) _{) F (CF 2) 8 (} CH 2) 2 OCOC (CH 3) = CH 2 (a-8) F (CF 2) 10 (CH 2) 2 OCOC (CH 3) = CH 2 (a-9) H _{(CF 2) 8 CH 2 OCOC} (CH 3) = CH 2 (a-10) (CF 3) 2 CF (CF 2) 6 (CH 2) 2 OCOC (CH 3) = CH 2 (a-11) ( _{CF 3) 2 CF (CF 2} ) 8 (CH 2) 2 OCOC (CH 3) = CH 2 (a-12) Specific examples of the general formula (B) include the following monomers (b-1) to (b-7). _{F (CF 2) 8 SO 2} N (CH 3) CH 2 CH 2 OCOCH = CH 2 (b-1) F (CF 2) 8 SO 2 N (CH 3) (CH 2) 4OCOCH = CH 2 (b- _{2) F (CF 2) 8} SO 2 N (CH 3) (CH 2) 10OCOCH = CH 2 (b-3) F (CF 2) 3 SO 2 N (C 2 H 5) C (CH 2 CH 3) _{HCH 2 OCOCH = CH 2 (b} -4) F (CF 2) 8 SO 2 N (CH 3) CH 2 CH 2 OCOC (CH 3) = CH 2 (b-5) F (CF 2) 3 SO 2 N _{(C 2 H 5) CH 2} CH 2 OCOC (CH 3) = CH 2 (b-6) F (CF 2) 3 SO 2 N (C 3 H 7) CH 2 CH 2 OCOC (CH 3) = CH 2 (b-7) Specific examples of the general formula (C) include the following monomers (c-1) to (c-4). _{F (CF 2) 2 CON (} C 2 H 5) CH 2 OCOCH = CH 2 (c-1) F (CF 2) 3 CON (CH 3) CH (CH 3) CH 2 OCOCH = CH 2 (c-2 _{) F (CF 2) 8 CON} (CH 2 CH 2 CH 3) CH 2 CH 2 OCOC (CH 3) = CH 2 (c-3) F (CF 2) 8 CON (C 2 H 5) CH 2 OCOC ( CH ₃ ) = CH ₂ (c-4) Specific examples of the general formula (D) include the following monomers (d-1) to (d-4). _{F (CF 2) 8 CH 2} CH (OH) CH 2 OCOCH = CH 2 (d-1) (CF 3) 2 CF (CF 2) 2 CH 2 CH (OH) CH 2 OCOCH = CH 2 (d-2 _{) F (CF 2) 8 CH} 2 CH (OH) CH 2 OCOC (CH 3) = CH 2 (d-3) (CF 3) 2 CF (CF 2) 2 CH 2 CH (OH) CH 2 OCOC (CH ₃ ) = CH ₂ (d-4) Specific examples of the general formula (E) include the following monomers (e-1) to (e-2). _{(CF 3) 2 CF (CH} 2) 6 CH 2 CH (OCOCH 3) CH 2 OCOCH = CH 2 (e-1) (CF 3) 2 CF (CH 2) 6 CH 2 CH (OCOCH 3) CH 2 OCOC (CH ₃ ) = CH ₂ (e-2) Specific examples of the general formula (F) include the following monomers (f-1) to (f-4).

[0024]

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[0025]

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[0026]

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[0027]

Embedded image Specific examples of the general formula (G) include the following monomers (g-1).

[0028]

Embedded image Examples of the fluorine-containing monomers other than the general formulas (A) to (G) include the following monomers. F (CF ₂ ) ₆ CH ₂ OCHＣＨCH ₂ F (CF ₂ ) ₈ CH ₂ OCH ＝ CH ₂ F (CF ₂ ) ₁₀ CH ₂ OCH ＝ CH ₂ F (CF ₂ ) ₆ CH ₂ OCF = CF ₂ F ( _{CF 2) 8 CH 2 OCF =} CF 2 F (CF 2) 10 CH 2 OCF = CF 2 F (CF 2) 6 CH = CH 2 F (CF 2) 8 CH = CH 2 F (CF 2) 10 CH = _{CH 2 F (CF 2) 6} CF = CF 2 F (CF 2) 8 CF = CF 2 F (CF 2) 10 CF = CF 2 CH 2 = CF 2 CF 2 = CF 2 formula (A) ~ (G Rf in the above is a polyfluoroalkyl group or a polyfluoroalkenyl group having 3 to 21 carbon atoms, and preferably a polyfluoroalkyl group or a polyfluoroalkenyl group having 6 to 10 carbon atoms. Carbon number 2
Below, the solvent resistance tends to decrease, and if the number of carbon atoms is 22 or more, the chain becomes considerably long and the polymerization conversion rate tends to decrease.

R ₁ is an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 4 carbon atoms. If it has more than 10 carbon atoms, it will have a long chain and the polymerization conversion tends to decrease. R ₂ is hydrogen or a methyl group. R ₃ is hydrogen or an alkyl group having 1 to 10 carbon atoms. Ar is an aryl group which may have a substituent.

Among the above-mentioned fluorine-containing monomers, a fluorine-containing monomer represented by the general formula (A) is preferable from the viewpoint of solvent resistance and polymerization conversion. Among the fluorine-containing monomers represented by the general formula (A), particularly preferred fluorine-containing monomers are shown below. _{F (CF 2) 8 (CH} 2) 2 OCOCH = CH 2 F (CF 2) 8 (CH 2) 2 OCOC (CH 3) = CH 2 (CF 3) 2 CF (CF 2) 6 (CH 2) 2 OCOCH = CH
₂ (CF ₃ ) ₂ CF (CF ₂ ) ₆ (CH ₂ ) ₂ OCOC (C
H ₃ ) = CH ₂ Next, as the alkyl (meth) acrylate having an alkyl chain length of 12 to 22 carbon atoms which is copolymerized with the above-mentioned fluorine-containing monomer, for example, lauryl (meth) acrylate, (meth) acrylic acid Dodecyl, tridecyl (meth) acrylate,
Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, and behenyl (meth) acrylate are preferably used. One or more of these monomers can be used.

Considering higher solvent resistance to non-aqueous electrolytes, hexadecyl (meth) acrylate and (meth) acrylate
Stearyl acrylate, isostearyl (meth) acrylate, and behenyl (meth) acrylate are preferred.

The reason why the solvent resistance is improved is that by copolymerizing an alkyl (meth) acrylate having an alkyl chain length of 12 to 22 carbon atoms, the molecular motion of the fluorinated polymer segment can be reduced at a relatively low temperature. It is considered that the crystallinity of the fluoroalkyl group and the like is improved and the solvent resistance is exhibited. Therefore, excellent solvent resistance to the non-aqueous electrolyte during drying at room temperature can be exhibited.

Forming a fluorinated polymer segment,
The ratio of the fluorine-containing monomer to the alkyl (meth) acrylate having an alkyl chain length of 12 to 22 carbon atoms is preferably 100/0 to 20/80 by weight, more preferably 95/100.
/ 5 to 50/50. The weight ratio of the fluorine-containing monomer is 2
If it is less than 0/80, the solvent resistance to the non-aqueous electrolyte tends to decrease.

Next, the non-fluorinated polymer segment constituting the other molecular chain of the block copolymer will be described. The monomer forming the non-fluorinated polymer segment is
It is selected so that it can exhibit adhesion to a current collector made of a metal material. Specific examples of the monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and glycidyl (meth) acrylate. Lower alkyl (meth) acrylate; n-butyl (meth) acrylate, isobutyl (meth) acrylate,
T-butyl (meth) acrylate, n (meth) acrylate
Higher alkyl (meth) acrylates such as hexyl, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate; vinyl acetate Vinyl esters of lower fatty acids such as acetic acid and propionic acid; vinyl esters of higher fatty acids such as vinyl caproate, vinyl 2-ethylhexanoate, vinyl laurate and vinyl stearate; aromatic vinyl-type monomers such as styrene, vinyltoluene and vinylpyrrolidone body;
Amide group-containing vinyl-type monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethylol (meth) acrylamide, N-butoxymethylol (meth) acrylamide; hydroxyethyl (meth) acrylate; Hydroxy group-containing vinyl monomers such as hydroxypropyl (meth) acrylate and allyl alcohol; carboxylic acid group-containing vinyl monomers such as (meth) acrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid; butadiene Vinyl chloride; vinylidene chloride; (meth) acrylonitrile; dibutyl fumarate; maleic anhydride; (meth) allyl glycidyl ether; alkali-metals of radically polymerizable unsaturated carboxylic acids such as itaconic acid, (meth) acrylic acid, crotonic acid; Salt, ammonium salt, organic Salts, organic amine salts; radical-polymerizable unsaturated monomer having a sulfonic acid group such as styrenesulfonic acid, and alkali metal salts thereof, ammonium salts, organic amine salts, organic amine salts; 2-hydroxy -
Quaternary ammonium salts derived from (meth) acrylic acid, such as 3-methacryloxypropyltrimethylammonium chloride; (meth) acrylates of alcohols with tertiary amino groups, such as diethylamino methacrylate; and And quaternary ammonium salts thereof. One or more of these monomers can be used.

Among these monomers, those which can exhibit good adhesion to the current collector are polar monomers having a polar functional group such as an acid group, a hydroxyl group and an epoxy group. For example, (meth) acrylic acid, itaconic acid, crotonic acid, fumaric acid,
Carboxylic acid group-containing vinyl monomers such as maleic acid;
Hydroxy group-containing vinyl monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and allyl alcohol; and glycidyl (meth) acrylate.

As the monomer forming the non-fluorinated polymer segment, a mixture of the above-mentioned polar monomer and other monomers is usually used. In that case, the ratio between the polar monomer and the other monomer is preferably 1/99 to 7 by weight.
0/30, more preferably 5/95 to 40/60. When the weight ratio of the polar monomer is less than 1/99, the adhesion to the current collector tends to decrease, and when it exceeds 70/30, a fluorine-containing block copolymer having excellent solution stability during solution polymerization is obtained. It tends to be difficult to obtain.

Further, in order to make the non-fluorine segment exhibit solvent resistance to the non-aqueous electrolyte, it is preferable to copolymerize a monomer having a crosslinking functional group. When an electrode mixture layer is formed by performing a heat treatment using a fluorinated block copolymer obtained by copolymerizing a monomer having a cross-linking functional group, a cross-linking reaction between the cross-linking functional groups proceeds, and the non-aqueous electrolyte solution It becomes possible to exhibit solvent resistance. Examples of the monomer having a cross-linking functional group include N-methylol (meth) acrylamide, N-methoxymethylol (meth) acrylamide, and N-butoxymethylol (meth) acrylamide.

Forming a non-fluorinated polymer segment;
The ratio of the monomer having a cross-linking functional group to the other monomer is preferably 1/99 to 50/50, more preferably 5/95 to 20/80 by weight. If the weight ratio of the monomer having a crosslinking functional group is less than 1/99, crosslinking tends to be insufficient, and if it exceeds 50/50, the adhesion to the current collector tends to decrease.

The ratio of the fluorinated polymer segment to the non-fluorinated polymer segment in the fluorinated block copolymer is preferably 10/90 to 80/20, more preferably 20/80 to 70 / by weight ratio. 30. If the weight ratio of the fluorinated polymer segment is less than 10/90, the arrangement of the perfluoroalkyl groups tends to be insufficient, and the solvent resistance to the non-aqueous electrolyte tends to be insufficient. Further, when the weight ratio of the fluorinated polymer segment exceeds 80/20, the non-fluorinated polymer segment is reduced, so that the adhesiveness to the substrate tends to decrease.

Next, a method for producing a fluorine-containing block copolymer will be described. The production of the fluorinated block copolymer is performed in two stages, a first step and a second step. First, in the first step, a monomer that forms one or more non-fluorine-based polymer segments (hereinafter abbreviated as a non-fluorine-based monomer) is polymerized using a polymeric peroxide as a polymerization initiator, This is a step of obtaining a peroxy bond-containing polymer. In the second step, the peroxy bond-containing polymer obtained in the first step is used as a polymerization initiator, and one or more fluorine-containing monomers, or a fluorine-containing monomer and a carbon number of an alkyl chain length. This is a step of polymerizing a mixture with 12 to 22 alkyl (meth) acrylates (hereinafter, these are referred to as fluorine-containing monomers) to obtain a fluorine-containing polymer segment.

In the above two-stage polymerization,
The non-fluorinated monomer in the first step may be used in the second step, and the fluorinated monomer in the second step may be used in the first step. This polymerization method uses a known production process (for example,
41668 or Japanese Patent Publication No. 5-59942).

The polymeric peroxide used for producing the above-mentioned fluorine-containing block copolymer is 2 per molecule.
A compound having two or more peroxy bonds. As the polymeric peroxide, one or more of various polymeric peroxides described in JP-B-5-59942 can be used.

For example, those represented by the following general formulas (1) to (3) can be used.

[0044]

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[0045]

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[0046]

Embedded image (N is an integer of 2 to 20.) The fluorine-containing block copolymer can be easily obtained by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method using the above-mentioned polymeric peroxide. For example, in the case of a solution polymerization method, a non-fluorine-based polymer segment in the first step as a fluorine-containing block copolymer, and an example of forming a fluorine-containing polymer segment in the second step will be described as follows. be able to.

That is, first, a non-fluorinated polymer containing a peroxy bond having a peroxy bond introduced into a chain is obtained by polymerizing a non-fluorinated monomer in a solution using a polymeric peroxide as a polymerization initiator. can get. Next, in the second step, when polymerization is performed by adding a fluorinated monomer to the solution produced in the first step, cleavage occurs at the peroxy bond in the non-fluorinated polymer containing a peroxy bond, which is efficiently performed. A fluorinated block copolymer is obtained.

The amount of the polymeric peroxide used in the first step is usually 0.5 to 20 parts by weight based on 100 parts by weight of the monomer used in the first step, and the polymerization temperature at that time is 40 to 130 parts. C. and the polymerization time is about 2 to 12 hours. The polymerization temperature in the second step is usually 40 to 1
At 40 ° C., the polymerization time is about 3 to 15 hours.

The molecular weight of the fluorinated block copolymer is preferably from 1,000 to 5,000,000, more preferably from 5,000 to 100,000 in terms of weight average molecular weight.
If the weight average molecular weight is less than 1,000, the solvent resistance to the non-aqueous electrolyte tends to be insufficient. On the other hand, if the weight average molecular weight exceeds 100,000, the adhesion to the current collector tends to decrease.

Next, the organic solvent and the diluting solvent during the solution polymerization will be described. The organic solvent is not particularly limited as long as it can dissolve or disperse the fluorinated block copolymer, for example, propyl alcohol, 2-propyl alcohol, 1-butyl alcohol, 2-butanone,
Preferred are butyl acetate, toluene, ethylbenzene, xylene, heptane, octane and the like.

Next, the binder solution for forming a non-aqueous battery electrode is a solution in which a fluorinated block copolymer is dissolved in an organic solvent, or a solution in which the fluorinated block copolymer is finely dispersed in an organic solvent. The ratio of the fluorinated block copolymer to the organic solvent in the binder solution is as follows.
The amount is preferably 1 to 70 parts by weight, particularly preferably 1 to 50 parts by weight, based on 00 parts by weight. If less than 1 part by weight,
Since the proportion of the fluorinated block copolymer in the solution is small, the effect as a binder tends to be reduced. On the other hand, if it exceeds 70 parts by weight, the viscosity of the solution itself may be too high, and it may be difficult to prepare an electrode mixture.

Next, a slurry obtained by dispersing and mixing a powdered electrode material in an organic solvent solution of a binder is referred to as a slurry for an electrode mixture. The slurry obtained by removing the organic solvent therefrom, ie, a powder made of a binder comprising a fluorine-containing block copolymer is used. Electrode material (electrode active material and conductive additive added as needed)
The combination of the two is called an electrode mixture.

As a method of producing the slurry for the electrode mixture, a method of preparing a slurry for the electrode mixture by preparing a binder solution and then adding a powdered electrode material, and a method of substantially preparing a fluorinated block copolymer and a powdered electrode material, At the same time, there is a method of mixing and dispersing in an organic solvent to prepare a slurry for an electrode mixture at once.

As a method for producing an electrode mixture, a powdered electrode material is mixed with a powder of a fluorinated block copolymer, and an electrode mixture layer is formed on a current collector by a melt molding method or a powder molding method. It is also possible to use it in the forming method.

The electrode mixture is preferably formed so as to contain 0.1 to 50 parts by weight of the fluorinated block copolymer with respect to 100 parts by weight of the powdered electrode material. When the amount of the fluorinated block copolymer is less than 0.1 part by weight, the effect as a binder for binding the powdered electrode materials to each other cannot be obtained. Since the battery is covered, the performance of the battery may be impaired.

The electrode mixture can be applied to both positive and negative electrodes of non-aqueous batteries. For example, as a positive electrode active material for a lithium ion secondary battery, a general formula LiMY ₂ (M
Is a complex metal chalcogen compound represented by at least one of transition metals such as Co, Ni, Mn, Cr and V: Y is a chalcogen element such as O and S), particularly LiNixCo _1-x O
₂ (0 ≦ x ≦ 1) and other complex metal oxides and Li
Composite metal compound takes a spinel structure such as Mn ₂ 0 ₄ is preferred.

Examples of the electrode active material for the negative electrode include graphite, activated carbon, and powdered carbonaceous materials such as those obtained by calcining carbonized phenolic resin and pitch.
It is preferable to add a composite oxide such as O ₂ , SnO, SnO ₂ , PbO, and PbO ₂ .

The conductive assistant is added for the purpose of improving the conductivity of the electrode mixture layer when using an electrode active material having a low electron conductivity such as LiCoO _2. Alternatively, a carbonaceous material such as fiber, fine metal powder with nickel or aluminum, or fiber is used.

Next, the electrode structure of the present invention will be described. As shown in the cross-sectional view of FIG. 1, the electrode structure 10 includes a current collector 11 in a plate shape, and electrode mixture layers 12a and 12b formed on both front and back surfaces of the current collector 11. I have. The current collector 11 is formed of a metal foil or a metal net of iron, stainless steel, steel, copper, aluminum, nickel, titanium, or the like. When manufacturing this electrode structure,
The above-mentioned electrode mixture slurry is applied to at least one surface, preferably both surfaces, of the current collector 11 so as to have a thickness of 5 to 100 μm. Then, it is dried at 50 to 170 ° C.,
The electrode structure 10 is formed by forming the electrode mixture layers 12a and 12b of 0 to 1000 μm.

Next, the non-aqueous battery of the present invention will be described. FIG. 2 is a partially exploded perspective view of a cylindrical lithium secondary battery as an example of a non-aqueous battery including the electrode structure formed as described above.

That is, in this lithium secondary battery, a separator 15 made of a microporous film of a polymer material such as polypropylene or polyethylene impregnated with an electrolyte is basically disposed between the positive electrode 13 and the negative electrode 14. Is done. A power generating element obtained by spirally winding the stacked body is electrically connected to the negative terminal 16 at the bottom, and the positive electrode 13 is electrically connected to the positive terminal 18 via the top plate 17 at the top. I have. Gasket 1 on top
9 and a safety valve 20 are arranged. Then, they are accommodated in the casing 21 and the top rim 22 is swaged. As the non-aqueous electrolyte solution impregnated in the separator 15, a solution in which an electrolyte is dissolved in a non-aqueous solvent (organic solvent) is used.

Here, as the electrolyte, LiPF ₆ , Li
AsF ₆ , LiClO ₄ , LiBF ₄ , LiCH ₃ SO ₃ ,
LiCF ₃ SO ₃ , LiN (CF ₃ OSO ₂ ) ₂ , LiC
(CF ₃ OSO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC
(CF ₃ SO ₂ ) ₃ , LiCl, LiBr and the like.

Organic solvents for the electrolyte, so-called non-aqueous electrolytes, include propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ- Butyrolactone,
Methyl propionate, ethyl propionate, a mixed solvent thereof and the like are used, but not limited thereto.

In the above embodiment, an example of a cylindrical battery is shown. However, the non-aqueous battery of the present invention can be configured as a coin-shaped battery, a square battery, or a paper battery. The effects exerted by the above-described embodiment will be summarized below.

According to the binder for forming a non-aqueous battery electrode described in the embodiment, the fluorinated polymer segment constituting the fluorinated block copolymer exhibits good solvent resistance to the non-aqueous electrolyte. be able to. In addition, the non-fluorine polymer segment having an affinity for the current collector can exhibit good adhesion to the current collector made of a metal material. Therefore, this binder is suitable as a binder for forming an electrode of a non-aqueous battery.

Further, the fluorinated polymer segment may be a fluorinated monomer alone or a fluorinated monomer, and a long-chain alkyl (meth) having 12 to 22 carbon atoms in the alkyl group.
By being formed from a mixture with acrylate, solvent resistance to a non-aqueous electrolyte can be improved.

Further, since the fluorine-containing monomer is a monomer represented by the aforementioned general formula (A), it is possible to increase the polymerization conversion rate from the fluorine-containing monomer to a polymer, Further, the solvent resistance to the non-aqueous electrolyte can be further improved.

The electrode mixture is obtained by binding the powdered electrode material with a binder for forming a non-aqueous battery electrode,
Good solvent resistance to the non-aqueous electrolyte and good adhesion to the current collector can be exhibited.

The electrode structure is formed by forming a layer of an electrode mixture on at least one surface of a plate-shaped current collector, and has good solvent resistance to a non-aqueous electrolyte and good adhesion to the current collector. It can demonstrate its properties.

The non-aqueous battery comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte disposed between the positive and negative electrodes,
At least one of the positive electrode and the negative electrode is the above-described electrode structure, and can exhibit good solvent resistance to a non-aqueous electrolyte and good adhesion to a current collector.

[0071]

The above embodiment will be described more specifically with reference to production examples, examples and comparative examples. (Production Example 1, Synthesis Example of Fluorine-Containing Block Copolymer) After introducing nitrogen gas into a 500 ml four-necked flask equipped with a thermometer, a drop float, a nitrogen gas inlet tube and a stirrer, 60.0 g of dimethylformamide was added. And heated to 70 ° C. Then, 40.0 g of n-butyl methacrylate, 10.0 g of methacrylic acid and polymeric peroxide [the above-mentioned general formula (1) (n = 10)] as an adhesive monomer.
0 g and 55.0 g of dimethylformamide in 2 parts
Dropped in time. Thereafter, the reaction was continued at 70 ° C. for 4 hours. Next, 50.0 g of the fluorine-containing monomer represented by the formula (a-2) and 116.7 g of dimethylformamide were added to 1
Dropped in time. Thereafter, the reaction was performed at 70 ° C. for 5 hours.

The obtained solution was heat-treated at 150 ° C. for 2 hours to remove dimethylformamide, and the weight was measured. As a result, 30% by weight of the dimethylformamide solution was a fluorine-containing block copolymer. The obtained fluorinated block copolymer was analyzed by pyrolysis GC (gas chromatography), and it was confirmed that the fluorinated polymer segment was 50% by weight and the non-fluorinated polymer segment was 50% by weight. I was able to. (Production Examples 2 to 5) In the synthesis of a fluorinated block copolymer,
A fluorinated block copolymer was obtained in the same manner as in Production Example 1, except that the types of the monomers constituting the non-fluorinated polymer segment and the fluorinated polymer segment were changed as shown in Table 1. (Production Examples 6 to 7) In the synthesis of the fluorine-containing block copolymer, the fluorine-containing block copolymer was mixed so that the ratio of the fluorine-containing polymer segment to the other segments in the fluorine-containing block copolymer became the value shown in Table 1. A fluorine-containing block copolymer was obtained in the same manner as in Production Example 1 except that the amounts of the fluorine monomer and the adhesive monomer were changed. (Production Example 8, Synthesis Example of Fluorine-Containing Random Copolymer) After introducing nitrogen gas into the four-necked flask described in Production Example 1,
175 g of dimethylformamide was added, and the temperature was raised to 60 ° C. Thereafter, 40.0 g of n-butyl methacrylate and 10.0 g of methacrylic acid were used as the adhesive monomer, and the above formula (a)
50 g of the fluorine-containing monomer represented by -2), 1.0 g of t-butyl peroxypivalate and dimethylformamide 5
0 g of the mixture was added dropwise over 2 hours. Thereafter, the reaction was continued at 60 ° C. for 7 hours.

As a result of heating residue measurement, 30% by weight of the solution in dimethylformamide was a fluorine-containing random copolymer. Further, it was confirmed by pyrolysis GC that the obtained fluorine-containing random copolymer was composed of 50% by weight of the fluorine-containing polymer and 50% by weight of the adhesive polymer. (Production Examples 9 to 12) The same as Production Example 8 except that the types of the adhesive monomer and the fluorine-containing monomer were changed as shown in Table 2 in the synthesis of the fluorine-containing random copolymer. (Production Examples 13 and 14) The same as Production Example 8 except that in the synthesis of the fluorine-containing random copolymer, the amounts of the fluorine-containing monomer and the adhesive monomer were changed so as to obtain the values shown in Table 2. To obtain a fluorinated block copolymer.

[0074]

[Table 1]

[0075]

[Table 2] (a-2): F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH = CH ₂ (a-6): (CF ₃ ) ₂ CF (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC
H = CH ₂ (b-2): F (CF ₂ ) ₈ SO ₂ N (CH ₃ ) (CH ₂ ) ₄ OC
OCH = CH ₂ SMA: Stearyl methacrylate SA: Stearyl acrylate nBMA: n-butyl methacrylate MAA: Methacrylic acid MMA: Methyl methacrylate HEMA: 2-Hydroxyethyl methacrylate NMAAm: N-methylol acrylamide EMA: Ethyl methacrylate EHMA : 2-ethylhexyl methacrylate GMA: glycidyl methacrylate (Examples 1 to 7) <Evaluation of swelling property of binder> Binder solution comprising fluorinated block copolymer of Production Examples 1 to 7 and dimethylformamide (resin content 30) % By weight) was adjusted to a resin content of 10% by weight using dimethylformamide. Each binder solution was cast on a fluororesin plate, and 6
Vacuum dried at 0 ° C. for 3 hours and at 110 ° C. for 12 hours. Then, after the temperature was lowered to room temperature, the film was peeled off from the fluororesin plate to form a 0.3 mm thick film (30 × 30 mm size). Each of the films was immersed in an electrolyte obtained from a mixed solution of 10 parts by weight of lithium perchlorate and 90 parts by weight of propylene carbonate,
The film was immersed at 80 ° C. for 5 days, and the degree of swelling was determined by the weight increase rate of the cast film [(film weight after immersion / film weight before immersion) × 100]. The results are summarized in Table 3. <Evaluation of Adhesiveness of Electrode Mixture Layer in Electrode Structure> LiMn ₂ O _{4 as} a positive electrode active material was added to 10 g of the binder solution (resin content: 10% by weight) of Production Examples 1 to 7 examined above.
7 g was ground on a mortar to obtain an electrode mixture slurry. This electrode mixture slurry was applied on an aluminum foil having a thickness of 10 μm with a doctor blade, and this was applied at 60 ° C. for 3 hours.
After drying under vacuum at 110 ° C. for 12 hours, an electrode structure having a total thickness of 100 μm was obtained. The adhesive strength between the layer of the electrode mixture and the aluminum foil as the current collector in this electrode structure was evaluated as a peel strength by a 180-degree peel test according to JIS K6854. The results are summarized in Table 3. (Comparative Examples 1 to 7) <Evaluation of swellability of binder> A binder solution (resin content: 30% by weight) composed of the fluorinated random copolymer and dimethylformamide of Production Examples 8 to 14 was prepared using dimethylformamide. Adjusted to 10% by weight per minute. The conditions for preparing the sample and the evaluation method were performed according to Examples 1 to 7. The results are summarized in Table 4. <Measurement of Peeling Strength> 7 g of LiMn ₂ O _4, which is an electrode active material of a positive electrode, was placed in a mortar on 10 g of a binder solution (resin content: 10% by weight) composed of the fluorinated random copolymer and dimethylformamide of Production Examples 8 to 14 above. To obtain an electrode mixture slurry. The conditions for preparing the sample and the evaluation method were performed according to Examples 1 to 7. The results are summarized in Table 4. (Comparative Example 8) <Evaluation of swellability of binder> Polyvinylidene fluoride (KF manufactured by Kureha Chemical Industry Co., Ltd.) so that the resin content becomes 10% by weight.
-1100) using N-methyl-2-pyrrolidinone to prepare a binder solution. The conditions for preparing the sample and the evaluation method were performed according to Examples 1 to 7. The results are shown in Table 4. <Measurement of Peeling Strength> LiMn ₂ O _{4 as} a positive electrode active material was added to 10 g of the above binder solution (resin content: 10% by weight).
7 g was ground on a mortar to obtain an electrode mixture. The conditions for preparing the sample and the evaluation method were performed according to Examples 1 to 7. The results are shown in Table 4.

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[Table 3]

[0077]

[Table 4] As described in Table 3, the non-aqueous battery electrode forming binders of Examples 1 to 7 had a low degree of swelling and exhibited good solvent resistance to propylene carbonate, which is a non-aqueous electrolyte. In addition, the peeling strength was high with respect to the aluminum current collector, no peeling was observed, and good adhesion was exhibited.

On the other hand, as shown in Table 4, when a fluorine-containing random copolymer and polyvinylidene fluoride were used instead of the fluorine-containing block copolymer (Comparative Examples 1 to 7)
Had a high degree of swelling and tended to swell slightly with respect to propylene carbonate, which is a non-aqueous electrolyte. Also,
The peel strength with respect to the aluminum current collector was low, and partial peeling was confirmed.

The technical idea grasped from the above embodiment will be described below. 4. The non-aqueous battery electrode according to claim 1, wherein the non-fluorinated polymer segment is formed from a monomer mixture containing a monomer having a crosslinkable functional group. 5. binder. With this configuration, the solvent resistance to the non-aqueous electrolyte can be further improved.

The monomer forming the non-fluorinated polymer segment is formed from a mixture of a polar monomer having a polar functional group and another monomer. Item 4. The binder for forming a non-aqueous battery electrode according to any one of Items 3. With this configuration, the adhesion to the current collector can be improved.

An organic solvent is formed by removing an organic solvent from a slurry for an electrode mixture in which a powdered electrode material is dispersed and mixed in an organic solvent solution of a binder for forming a nonaqueous battery electrode according to any one of claims 1 to 3. The electrode mixture according to claim 4. In such a configuration, the powder electrode material can be easily bonded with the binder made of the fluorine-containing block copolymer.

[0082]

As described above, according to the present invention, the following effects can be obtained.

According to the binder for forming a non-aqueous battery electrode of the first invention, the solvent resistance to the non-aqueous electrolyte is good,
In addition, it can exhibit good adhesion to the current collector, and is suitable as a binder for forming an electrode of a non-aqueous battery.

According to the non-aqueous battery electrode forming binder of the second invention, in addition to the effects of the first invention, the solvent resistance to the non-aqueous electrolyte can be improved. According to the binder for forming a non-aqueous battery electrode of the third invention, in addition to the effect of the second invention, it is possible to increase the polymerization conversion rate from a fluorine-containing monomer to a polymer and to improve the non-aqueous electrolyte. Solvent resistance can be further improved.

According to the electrode mixture of the fourth invention, the electrode mixture is obtained by binding the powdered electrode material with the binder for forming a non-aqueous battery electrode of any of the first to third inventions. It can exhibit good solvent resistance and good adhesion to the current collector.

According to the electrode structure of the fifth invention, a layer of the electrode mixture of the fourth invention is formed on at least one surface of the current collector in the form of a plate. It can exhibit solvent resistance and good adhesion to the current collector.

According to the nonaqueous battery of the sixth invention, the positive electrode,
A negative electrode and a non-aqueous electrolyte solution disposed between the positive electrode and the negative electrode thereof, at least one of the positive electrode and the negative electrode is an electrode structure of the fifth invention, and a good solvent resistance to the non-aqueous electrolyte solution, Good adhesion to the current collector can be exhibited.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating an electrode structure of a nonaqueous battery according to an embodiment.

FIG. 2 is a partially exploded perspective view showing the non-aqueous secondary battery in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Electrode structure, 11 ... Current collector, 12a, 12b ... Electrode mixture layer, 13 ... Positive electrode, 14 ... Negative electrode, 15 ... Separator.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ02 AK03 AL06 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ08 EJ12 HJ02 5H050 AA01 BA17 CA08 CA09 CB08 DA02 DA03 DA11 EA10 EA24 HA02

Claims (6)

[Claims] 1. A fluorinated block copolymer comprising a fluorinated polymer segment formed from a fluorinated monomer and a non-fluorinated polymer segment formed from a non-fluorinated monomer. A non-aqueous battery electrode forming binder comprising: 2. The fluorinated polymer segment is formed from a single fluorinated monomer or a mixture of a fluorinated monomer and an alkyl (meth) acrylate having 12 to 22 carbon atoms in an alkyl group. The binder for forming an electrode for a non-aqueous battery according to claim 1. 3. The binder for forming a non-aqueous battery electrode according to claim 2, wherein the fluorine-containing monomer is one or more of monomers represented by the following general formula (A). Embedded image (Rf is a fluoroalkyl group or fluoroalkenyl group having 3 to 21 carbon atoms, R ¹ is an alkylene group having 1 to 10 carbon atoms, and R ² is hydrogen or a methyl group.) 4. An electrode mixture obtained by binding a powdered electrode material with the binder for forming a non-aqueous battery electrode according to any one of claims 1 to 3. 5. An electrode structure comprising the plate-like current collector and the electrode mixture layer according to claim 4 formed on at least one surface of the current collector. 6. A non-aqueous battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode is the electrode structure according to claim 5. Non-aqueous battery characterized by the above-mentioned.