JPH1167213A - Composition for battery electrode and battery electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure current collecting capability of an electrode active material, enhance the utilization efficiency of the active material, lengthen the life and increase the capacity of a battery by using a binder containing carboxymethylcellulose having a specified degree of etherification and mean degree of polymerization and polymer latex. SOLUTION: A binder containing carboxymethylcellulose (CMC) having a degree of etherification of 0.5-1 and a mean degree of polymerization of 300-1,800 and polymer latex is used in an electrode for a battery. The carboxymethylcellulose is one kind of cellulose ether, that is, cellulose grycolate, and has structure represented by the formula. In the formula, R represents a group selected from -H and -CH2 COOX, and X represents a group selected from Na, NH4 , Ca, K, Al, Mg, and H. In the case that R and X are plural, they may be the same or different, and (n) is an integer of 300-1,800.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery electrode having excellent discharge characteristics, high capacity, charge / discharge cyclability, and safety.
More specifically, the present invention relates to a battery electrode composition suitable for a battery electrode in which an electrode active material is held by a current collector.

[0002]

2. Description of the Related Art In recent years, the development of electronics has been remarkable, and accordingly, technological progress in the electronic equipment industry has been remarkable, and demands for battery technology such as high energy density and safety have been increasing. Since conventional nickel-cadmium batteries cannot be used to satisfy such demands, nickel-metal hydride batteries that use a hydrogen storage alloy instead of cadmium for the negative electrode, and lithium-ion batteries that are non-aqueous batteries have attracted attention. . Lithium ion batteries have features of high energy density, good storage stability, and small size and light weight. Nickel-metal hydride batteries are capable of rapid charging and discharging, are resistant to overcharging and overdischarging, are compatible and similar to nickel-cadmium batteries, and can be used to replace equipment that currently uses nickel-cadmium batteries. is there. In general, the electrodes of these batteries are obtained by applying a slurry-like composition for a battery electrode comprising an electrode active material and a binder to a current collector. The performance required for the composition for a battery electrode is that the binding property between the electrode active material and the current collector is good, ions in the electrolytic solution can be freely moved as much as possible without any resistance, That the volume does not change. The composition for battery electrodes may contain additives such as a dispersant and a binder as necessary.
These are used for the purpose of improving the dispersibility of the electrode active material in the binder and firmly fixing the electrode active material to the current collector. However, in the conventional composition for a battery electrode, the binder and the additive significantly affect the electrode active material, and it is difficult to satisfy all of the above conditions.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a secondary battery mainly with which to secure the current collecting property of an electrode active material, improve its use efficiency, extend the life of the battery and increase the capacity. To achieve.

[0004]

According to the present invention, (A) the degree of etherification is 0.5-1 and the average degree of polymerization is 300-18.
Carboxymethylcellulose (hereinafter referred to as “CM
C)) and (B) a polymer latex.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. <Carboxymethylcellulose> Carboxymethylcellulose used in the present invention is a kind of cellulose ether and is a cellulose glycolate, and has a structure of the following formula (1).

[0006]

Embedded image

Wherein R is —H and —CH ₂ COOX
X represents Na, NH ₄ , Ca, K,
A group selected from Al, Mg and H;
May be the same or different when n exists, and n represents an integer of 300 to 1800. )

In the chemical structure represented by the above formula (1), a carboxymethyl group is ether-bonded to a hydroxyl group of cellulose. Generally, CMC refers to a sodium salt, but there are also special salts such as ammonium salts and calcium salts, and glycolic acid which is soluble in an alkaline aqueous solution but insoluble in water. As the CMC used in the present invention, any one may be used. , Sodium salts, potassium salts and glycolic acid are preferred. In particular, when used for a lithium ion battery electrode, it is considered that the presence of miscellaneous ions other than lithium ions adversely affects the charge / discharge characteristics of the ions, which may cause deterioration in cycle characteristics and decrease in capacity. .

The CMC of the present invention is produced, for example, by reacting pulp with sodium monochloroacetate and sodium hydroxide. Cellulose in pulp is a polysaccharide composed of a series of anhydrous glucose monomer units, and has three hydroxyl groups in one monomer unit. CMC is synthesized by a substitution reaction between these hydroxyl groups and sodium monochloroacetate. By varying the amount of sodium monochloroacetate, various CMCs having different degrees of substitution can be produced. The production methods are roughly classified into three methods: an Arcelle method, a monochrome method, and a solvent method. The synthesis reaction is usually represented by the following formula (2).

Rcell (OH) ₃ + xClCH ₂ COONa + xNaOH → Rcell (OH) _3-x (OCH ₂ COONa) _x + xNaCl + xH ₂ O (2) (where Rcell (OH) ₃ is an anhydrous glucose monomer unit in cellulose) And x represents a number of 0.1 to 3.)

The CMC obtained by the above method contains a large amount of sodium chloride, sodium glucose, a small amount of sodium carbonate and the like as impurities. Examples of such a method for purifying CMC include an aqueous medium method, a sulfuric acid purification method, and a methanol purification method. In the case of obtaining a high purity, it is preferable to use a sulfuric acid purification method or a methanol purification method.

In the above CMC, the number of carboxymethyl groups ether-bonded to one monomer unit of anhydrous glucose, that is, the value of x in the above formula (2) is
It is called the degree of etherification. The degree of etherification is determined as an average value of the entire CMC and serves as an index of the water solubility of the CMC. CMC having a degree of etherification of 0.1 to 0.3 is insoluble in water, and becomes soluble in water when the degree of etherification is 0.5 or more. However, the degree of etherification needs to be 0.6 or more for complete transparency. There is. The degree of etherification of CMC can theoretically be a value of up to 3, but the degree of etherification of CMC used in the present invention is 0.5 to 1, preferably 0.55 to 0.9,
Particularly preferably, it is 0.6 to 0.85. When the degree of etherification is less than 0.5, the workability is poor because CMC is insoluble or difficult to dissolve in water, and the dispersibility, coating strength and adhesive strength are poor due to the small amount of carboxymethyl groups. If the degree of etherification exceeds 1, the resulting coating film is hard and inferior in flexibility, the resulting electrode has poor binding properties between the electrode active material and the current collector, and further has an affinity for the electrolytic solution. And the charge / discharge cycle becomes worse.

Further, as a value representing the characteristic of the CMC, the value of n in the above formula (1), that is, the degree of polymerization can be mentioned. The average degree of polymerization in the entire CMC has a correlation with the viscosity of the CMC aqueous solution, and the CMC has a thickening effect, a dispersing effect,
It has an effect on adhesiveness. The average degree of polymerization of CMC used in the present invention is in the range of 300 to 1800, preferably 5 to 1800.
It is from 00 to 1500, more preferably from 600 to 1400. When the average degree of polymerization is less than 300, the viscosity of the CMC aqueous solution used in the present invention may be too low, and the viscosity increasing effect, the coating film strength, and the adhesion are poor. The average degree of polymerization is 18
If it exceeds 00, the viscosity of the CMC aqueous solution may be too high, and the workability is poor, and the coating properties and adhesion are undesirably reduced. Further, when the average degree of polymerization is in the above range, the viscosity (25 ° C., 60 rotations) of a 1% by weight aqueous solution of CMC used in the present invention is 200 to 4000 mPa.
S is preferred.

In the present invention, CMC is the electrode active material 1
It is used in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, as a solid content based on 00 parts by weight. When the amount of the CMC is less than 0.1 part by weight, the dispersibility of the electrode active material is poor, and the coating property on the current collector is deteriorated. Adhesion may be inferior, and if it exceeds 20 parts by weight, overvoltage may increase significantly and adversely affect battery characteristics.

<Polymer Latex> The polymer latex used in the present invention includes SB latex and NBR.
Latex, acrylic latex, silicone latex, fluorine latex and the like. Preferred are SB-based latex and NBR-based latex, and more preferred are SB-based latex. Examples of the SB latex include conjugated diene monomer units, (meth) acrylate monomer units, aromatic vinyl monomer units, ethylenically unsaturated carboxylic acid monomer units, and other copolymerizable functional units. Those comprising a group-containing monomer are preferred. The NBR latex is preferably composed of a vinyl cyanide monomer unit, a conjugated diene monomer unit, an ethylenically unsaturated carboxylic acid monomer unit and other copolymerizable monomer units. . The acrylic latex is preferably composed of an alkyl acrylate monomer unit, an ethylenically unsaturated carboxylic acid monomer unit, and other copolymerizable monomer units. Further, as the silicone latex,
In the presence of an aqueous dispersion of a polyorganosiloxane-based polymer obtained by cocondensing a graft crosslinking agent with an organosiloxane as necessary, an alkyl acrylate monomer unit, an ethylenically unsaturated carboxylic acid monomer What consists of a unit and other copolymerizable monomer units is preferable. Further, as the fluorine-based latex, a functional group-containing vinylidene fluoride-based polymer is preferable.
Those described in 258499 are particularly preferred.

These polymer latexes can be produced by emulsion polymerization of the above monomer units. Further, the polymer latex used in the present invention preferably comprises an aqueous dispersion. The average particle size of the polymer particles dispersed in the aqueous dispersion is preferably from 70 to 400 nm, more preferably from 80 to 350 nm, and the solid content of the aqueous dispersion is usually from 20 to 65% by weight, preferably from 35 to 35% by weight. ~
60% by weight. These polymer particles may have a core-shell structure. In the present invention, the polymer latex is 0.1 to 20 parts by weight, preferably 0.5 to 1 part by weight, based on 100 parts by weight of the electrode active material.
Used in a proportion of 0 parts by weight. If the amount of the polymer latex is less than 0.1 part by weight, good adhesion to a current collector may not be obtained. If the amount exceeds 20 parts by weight, overvoltage may increase significantly and adversely affect battery characteristics. is there.

<Composition for Battery Electrodes> The composition for battery electrodes of the present invention is obtained by mixing and dispersing an electrode active material in a binder containing a CMC aqueous solution and a polymer latex. This composition for battery electrodes can be used for both aqueous batteries and non-aqueous batteries. Excellent performance can be obtained with a nickel-metal hydride battery negative electrode as an aqueous battery and a lithium ion battery negative electrode as a non-aqueous battery. As the above-mentioned electrode active material, a hydrogen storage alloy powder is used in an aqueous battery, particularly a nickel-metal hydride battery, and a material in which a part of Ni is replaced with Mn, Al, Co or the like based on MmNi ₅ is preferably used. Here, Mm represents a misch metal which is a mixture of rare earth elements. The shape of the powder is a powder that has passed through 100 mesh, and the particle size is about 3 to 400 μm. In a non-aqueous battery, for example, MnO
₂ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , Fe ₂ O ₃ , Fe
₃ O ₄ , Li _(1-x) CoO ₂ , Li _(1-x) NiO ₂ ,
Li _x Coy Sn _z O ₂ , Li _(1-X) Co _(1-y) Ni _y
O ₂ , TiS ₂ , TiS ₃ , MoS ₃ , FeS ₂ , Cu
Inorganic compounds such as F ₂ and NiF ₂ ; carbon fluoride, graphite, vapor-grown carbon fiber and / or its crushed product, PAN-based carbon fiber and / or its crushed product, pitch-based carbon fiber and / or its crushed product, etc. Conductive materials such as polyacetylene and poly-p-phenylene. In particular, Li _(1-x) CoO ₂ ,
_{Li (1-x) NiO 2} , Li x Co y Sn z O 2, Li
_{(1-X) Co (1} -y) in the case of using the Ni _y O ₂ lithium ion-containing composite oxide such as, a preferred combination it is possible to assemble in the positive and negative electrodes both discharged.

<Battery electrode> The battery electrode of the present invention is obtained by applying the composition for a battery electrode of the present invention, preferably in the form of a slurry, to a current collector, heating and drying as necessary. Examples of current collectors include Ni mesh, punched Ni, and Ni-plated punched metal for water-based batteries, and aluminum foil, copper foil, and the like for non-aqueous batteries. As a method of applying the composition for a battery electrode, a reverse roll method, a comma bar method, a gravure method, any method such as an air knife method can be used, and as a drying method, standing drying, blast drying, hot air drying, An infrared heater, a far infrared heater and the like can be used.
The drying temperature is usually around 150 ° C.

When assembling a battery using the battery electrodes obtained as described above, the non-aqueous electrolyte used is usually an electrolyte dissolved in a non-aqueous solvent. The electrolyte is not particularly limited, but examples of an alkaline secondary battery include LiClO ₄ , LiB
F ₄ , LiAsF ₆ , CF 3 SO ₃ Li, LiPF ₆ ,
LiI, LiAlCl ₄ , NaClO ₄ , NaBF ₄ ,
_{NaI, (n-Bu) 4} NClO 4, (n-Bu) 4 N
BF ₄ , KPF _{6 and the} like. Examples of the solvent used for the electrolyte include ethers, ketones, lactones, nitriles, amines, amides, sulfur compounds, chlorinated hydrocarbons, esters, carbonates,
Nitro compounds, phosphate compounds, sulfolane compounds and the like can be used, and among them, ethers, ketones, nitriles, chlorinated hydrocarbons, carbonates, and sulfolane compounds are preferable. Specifically, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, anisole, monoglyme,
Acetonitrile, propionitrile, 4-methyl-2-
Pentanone, butyronitrile, valeronitrile, benzonitrile, 1,2-dichloroethane, γ-butyrolactone, dimethoxyethane, methylformate, propylene carbonate, ethylene carbonate, dimethylformamide, dimethylsulfoxide, dimethylthioformamide, sulfolane, 3-methyl- Examples thereof include sulfolane, trimethyl phosphate, triethyl phosphate, and a mixed solvent thereof, but are not necessarily limited thereto. As an electrolyte for aqueous batteries, usually 5
More than specified potassium hydroxide is used.

Further, if necessary, a separator, a current collector,
A battery is configured using components such as terminals and insulating plates. Further, the structure of the battery is not particularly limited, but a positive electrode, a negative electrode, a paper type battery having a single-layer or multiple-layer separator as needed, or a positive electrode, a negative electrode, and a roll of the separator if necessary. An example is a form of a cylindrical battery wound in a shape. The battery electrode manufactured using the battery electrode binder of the present invention can be suitably used specifically for AV equipment, OA equipment, communication equipment, and the like.

[0021]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these embodiments. Each evaluation method in Examples and Comparative Examples is shown below. I. Evaluation of CMC Measurement of Degree of Etherification About 1.0 g of CMC vacuum-dried at 75 ° C. for 3 hours was accurately weighed, incinerated in a crucible, cooled, and then eluted with warm water to elute incinerated N / 10 sulfuric acid. After adding 40 ml, the mixture was acidified and boiled. After cooling, excess acid was back titrated with N / 10 sodium hydroxide, and the degree of etherification was determined by the amount of sulfuric acid consumed to neutralize the alkali in the ash. Measurement of Average Degree of Polymerization The intrinsic viscosity η was determined using a capillary viscometer (Cannon Fenske 0-5254 (model number)). This was applied to the following equation (3) to determine the weight average molecular weight Mw, and the average degree of polymerization was determined from this value.

[0022]

Η = 6.46 × 10 ⁻¹⁶ Mw (3)

II. The copper foil of the binder of thickness 50μm with evaluation copper foil of the lithium ion battery electrode composition as the substrate, the battery electrode composition by a roll coater and coated at a thickness of 200 g / m ^2, 15
After drying at 0 ° C for 10 minutes, press at room temperature to a thickness of 60
A μm copper foil coating film was obtained. Using the obtained copper foil coating film, the film strength was measured with a Clemens type “scratch hardness meter” (manufactured by Tester Sangyo Co., Ltd.). The measuring method is JI
SK5400 was carried out according to 8.4.1. Conductivity measurement method A composition for a battery electrode was added to a
Coating was performed at a thickness of 0 g / m ² and dried at 150 ° C. for 10 minutes to obtain a coating film having a thickness of 120 μm. Using this, electric resistance was measured by a four-terminal method. Electrolytic solution resistance The above copper foil coating film was coated with LIPASTE-EDEC / 1
(LiCLO4 / ethylene carbonate / diethyl carbonate (weight ratio) = 8.4 / 52.8 / 38.8, manufactured by Fuji Pharmaceutical Co., Ltd.) at 80 ° C. for 72 hours. Peeling was evaluated by a five-point method. The evaluation criteria were 5 points when there was no change at all and 1 point when completely peeled.

III. Evaluation of composition for nickel-hydrogen battery electrode Binding property to Ni mesh Using a 1-mm thick Ni mesh as a base material, a battery electrode composition was applied with an applicator at a thickness of 400 g / m ² , and at 150 ° C. Dry and crimp for 20 minutes, thickness 200μm
Was obtained. An adhesive tape was attached to the obtained coating film, and after peeling, the binding property was evaluated by a five-point method based on the condition of the coating film attached to the adhesive surface. The evaluation criteria were 5 points when the coating film hardly adhered to the adhesive surface, and 1 point when the coating film on the entire adhesive surface was peeled off. Conductivity measurement method A composition for a battery electrode was added to a
Coating was performed at a thickness of 0 g / m ² and dried at 150 ° C. for 10 minutes to obtain a coating film having a thickness of 120 μm. Using this, electric resistance was measured by a four-terminal method. Electrolytic solution resistance The Ni mesh coating film was immersed in an electrolytic solution composed of a 6N potassium hydroxide aqueous solution at room temperature for 24 hours, and peeling from the Ni mesh was evaluated by a five-point method. The evaluation criteria were 5 points when there was no change at all and 1 point when completely peeled.

(1) Production of CMC Synthesis Example 1 5730 ml of 88% aqueous 2-propanol solution was put into a Werner-type crusher, and 191 g of pulp pieces cut into about 2 cm squares were completely dried and stirred at high speed while stirring. The mixture was crushed and sufficiently stirred until the uncrushed pulp disappeared to form a slurry. After the obtained slurry was cooled to room temperature, 23 g of sodium hydroxide was added to a crusher to prepare alkali cellulose, and the mixture was ice-cooled again to 10 ° C. or lower. 54 g of monochloroacetic acid was added to the ice-cooled alkali cellulose, stirred for 1 minute, cooled to 5 ° C., and allowed to stand for 1.5 hours. Thereafter, the slurry was placed in a three-necked flask equipped with a stirrer and a reflux condenser, heated in a hot water bath, boiled, and reacted at the boiling point for 2 hours. After completion of the reaction, 3% hydrochloric acid was added in excess, and after stirring for several minutes, the reaction solution was cooled to room temperature. Thereafter, washing and filtration were repeated several times with an 80% aqueous methanol solution to remove sodium ions and chloride ions. As a method for detecting sodium ions, uranyl zinc acetate was dropped into the filtrate and irradiated with ultraviolet rays to examine the presence or absence of green-yellow crystals. The absence of crystals confirmed the removal of sodium ions.
As a method for detecting chloride ions, silver nitrate was dropped into the filtrate, and the presence or absence of precipitation of silver chloride was examined. It was confirmed that no precipitation occurred. After sodium ions and chloride ions were no longer detected, an excess of 3% aqueous ammonia was added, and the mixture was stirred for several minutes, and the product was dried to obtain an ammonium salt type CMC (1). The obtained CMC (1) had a degree of etherification of 0.65 and an average degree of polymerization of 850. Synthesis Example 2 5730 ml of 88% 2-propanol aqueous solution was put into a Werner-type crusher, and pulp pieces cut into about 2 cm squares were completely dried, and 191 g of the pulp pieces were crushed and crushed while being stirred at high speed to remove uncrushed pulp. The mixture was sufficiently stirred until a slurry was formed. After the obtained slurry was cooled to room temperature, 28 g of sodium hydroxide was added to a crusher to prepare alkali cellulose, and the mixture was ice-cooled again to 10 ° C. or lower. 67 g of monochloroacetic acid was added to the ice-cooled alkali cellulose, stirred for 1 minute, cooled to 5 ° C., and allowed to stand for 1.5 hours. Thereafter, the slurry was placed in a three-necked flask equipped with a stirrer and a reflux condenser, heated and boiled in a water bath, and reacted at the boiling point for 3 hours. After completion of the reaction, 3% hydrochloric acid was added in excess, and after stirring for several minutes, the reaction solution was cooled to room temperature. Thereafter, washing and filtration were repeated several times with an 80% aqueous methanol solution to remove sodium ions and chloride ions, and the product was dried to obtain glycolic acid type CMC (2). The obtained CMC (2) had a degree of etherification of 0.8 and an average degree of polymerization of 1300.

Synthesis Example 3 5730 ml of an 88% 2-propanol aqueous solution was put into a Werner-type crusher, 191 g of pulp pieces cut into about 2 cm squares were completely dried, and crushed while stirring at high speed to obtain uncrushed pulp. The mixture was sufficiently stirred until disappeared to form a slurry. After the obtained slurry was cooled to room temperature, 39 g of potassium hydroxide was added to a crusher to form an alkali cellulose, which was then ice-cooled to 10 ° C. or less again. 67 g of monochloroacetic acid was added to the ice-cooled alkali cellulose, stirred for 1 minute, cooled to 5 ° C., and allowed to stand for 1.5 hours. Thereafter, the slurry was placed in a three-necked flask equipped with a stirrer and a reflux condenser, heated in a hot water bath, boiled, and reacted at the boiling point for 3 hours.
After completion of the reaction, the reaction solution was cooled to room temperature, washed and filtered several times with an 80% aqueous methanol solution to remove chloride ions, and then the product was dried to obtain potassium salt type CMC (3). The obtained CMC (3) had a degree of etherification of 0.8 and an average degree of polymerization of 1300. Synthesis Example 4 A sodium salt type CMC (4) was obtained in the same manner as in Synthesis Example 3 except that 28 g of sodium hydroxide was used instead of 39 g of potassium hydroxide. The obtained CMC (4) had a degree of etherification of 0.8 and an average degree of polymerization of 1300. Synthesis Example 5 An ammonium salt type CMC (5) was obtained in the same manner as in Synthesis Example 1 except that 28 g of sodium hydroxide and 67 g of monochloroacetic acid were added and the reaction time at the boiling point was 3 hours. Was. The obtained CMC (5) had a degree of etherification of 0.8 and an average degree of polymerization of 1300.

Comparative Synthesis Example 1 In the same manner as in Synthesis Example 4, except that 11 g of sodium hydroxide and 25 g of monochloroacetic acid were added and the reaction time at the boiling point was 1.5 hours, a sodium salt type was prepared. CMC (6) was obtained. The obtained CMC (6) had a degree of etherification of 0.3 and an average degree of polymerization of 500. Comparative Synthesis Example 2 A sodium salt type CM was prepared in the same manner as in Synthesis Example 4 except that the reaction time at the boiling point was changed to 1 hour.
C (7) was obtained. The obtained CMC (7) had a degree of etherification of 0.8 and an average degree of polymerization of 100. Comparative Synthesis Example 3 A sodium salt type CM was prepared in the same manner as in Synthesis Example 4 except that the reaction time at the boiling point was changed to 5 hours.
C (8) was obtained. The obtained CMC (8) had a degree of etherification of 0.8 and an average degree of polymerization of 2500.

(2) Polymerization of Polymer Latex Synthesis Example 6 70 parts of ion-exchanged water and 0.3 part of potassium persulfate were charged into an autoclave equipped with a stirrer, and the gas phase was replaced with nitrogen gas for 15 minutes. The temperature was raised to 80 ° C. On the other hand, monomer components of 22% by weight of butadiene, 61% by weight of styrene, 12% by weight of methyl methacrylate, 1% by weight of acrylic acid, 2% by weight of methacrylic acid and 2% by weight of N-methylolacrylamide are mixed in a separate container, The solution was dropped into the autoclave over 15 hours. During the dropwise addition, the reaction was carried out at 80 ° C. After the completion of the dropwise addition, the mixture was further stirred at 85 ° C. for 5 hours to terminate the reaction. After cooling to 25 ° C., the pH was adjusted to 7 with potassium hydroxide, then steam was introduced to remove residual monomers, and then concentrated to obtain an SB-based latex (i) composed of an aqueous dispersion. Synthesis Example 7 70 parts of ion-exchanged water and 0.3 part of potassium persulfate were charged into an autoclave equipped with a stirrer, the gas phase was replaced with nitrogen gas for 15 minutes, and the temperature was raised to 80 ° C. On the other hand, monomer components of acrylonitrile 20% by weight, butadiene 45% by weight, styrene 29% by weight, methyl methacrylate 5% by weight, and itaconic acid 1% by weight were mixed in a separate container,
The solution was dropped into the autoclave over 15 hours. During the dropwise addition, the reaction was carried out at 80 ° C. After dropping, 85 ° C
After stirring for 5 hours at, the reaction was terminated. After cooling to 25 ° C., the pH was adjusted to 7 with potassium hydroxide, and then steam was introduced to remove residual monomers, and then concentrated to obtain an NBR latex (ii) composed of an aqueous dispersion.

Examples 1 to 5 and Comparative Examples 1 to 4 (3) Preparation of Lithium Ion Battery Electrode Composition 100 parts by weight of a pulverized needle coke (average particle size: 12 μm), the polymer latexes (i) and (ii) ) And 1 part by weight of polyvinylidene fluoride (denoted as (iii) in the table), 1 part by weight of the CMC aqueous solution (1) to (8) in solid content, and 0.5 part by weight of 0.5N ammonia water. The mixture was mixed to produce a composition for a lithium ion battery electrode, and the composition was evaluated. Table 1 shows the evaluation results.

[0030]

[Table 1] * Conductivity unit: mΩ / cm

(4) Preparation of Lithium Secondary Battery Li _1.03 Co _0.95 Sn _0.042 O ₂ 10 having an average particle size of 2 μm
0 parts by weight, 7.5 parts by weight of graphite powder, and 2.5 parts by weight of acetone black are mixed, and 50 parts by weight of a solution of fluoro rubber in methyl isobutyl ketone (concentration: 4% by weight) is added, and mixed and stirred. did. This is commercially available A1 foil (thickness 1
5 μ) was applied and dried at 290 g / m ² to obtain a positive electrode having a thickness of 110 μm. Next, the copper foil coating film obtained from the composition for a battery electrode was used as a negative electrode, and 0.9 cm
The sheet was cut into a size of 5.5 cm to assemble a lithium secondary battery. This battery was charged to 4.2 V and was charged at 100 mA.
The cycle of discharging to 5 V was repeated, and the capacity retention was measured. A cell charged to 4.2 V was charged at 70 ° C. × 30.
It was stored for days and the rate of capacity decrease was measured. Table 2 shows the evaluation results.

[0032]

[Table 2]

Examples 6 to 10 and Comparative Examples 5 to 8 (5) Preparation of composition for nickel-metal hydride battery electrode Hydrogen storage alloy powder having an average particle size of 170 μm (La: 0.
99% by weight, Ni: 3.41% by weight, Co: 1.20% by weight, Mn: 0.10% by weight, Al: 0.29% by weight)
100 parts by weight, 1 part by weight of the polymer latex (i), (ii) and polyvinylidene fluoride (described as (iii) in the table) and 1 part by weight of the CMC aqueous solution (1) to (8) in solid content The mixture was mixed well to produce a composition for a battery electrode, and the above evaluation was performed. Table 3 shows the evaluation results.

[0034]

[Table 3] * Conductivity unit: mΩ / cm

(5) Preparation of Nickel-Hydrogen Battery Nickel oxide as a positive electrode and the above-mentioned Ni mesh battery electrode as a negative electrode were cut into 0.9 cm × 5.5 cm, and Ni lead wires were welded to each, and 6N potassium hydroxide was used. A nickel hydrogen battery was assembled by using the aqueous solution as an electrolyte and combining with a separator. This battery was repeatedly charged to 2.0 V and discharged at 100 mA to 1.0 V, and the capacity retention was measured. The cell charged to 2.0 V was stored at 70 ° C. for 30 days, and the capacity reduction rate was measured. Table 4 shows the results.

[0036]

[Table 4]

[0037]

Industrial Applicability The composition for a battery electrode of the present invention secures the current collecting property of the electrode active material in a battery, mainly a secondary battery, improves its use efficiency, prolongs the life of the battery and increases the capacity. Can be achieved. Further, the battery electrode of the present invention can be a secondary battery electrode excellent in high capacity, discharge performance, charge / discharge cycleability, and safety.

Claims (2)

[Claims] 1. A binder comprising (A) carboxymethyl cellulose having a degree of etherification of 0.5 to 1 and an average degree of polymerization of 300 to 1800 and (B) a polymer latex. Composition for a battery electrode. 2. An electrode active material comprising: (A) a binder containing carboxymethylcellulose having a degree of etherification of 0.5 to 1 and an average degree of polymerization of 300 to 1800; and (B) a polymer latex. Are mixed and dispersed, and applied to a current collector, thereby obtaining a battery electrode.