Carboxymethylcellulose and / or its salts, electrode composition for non-aqueous electrolyte secondary batteries, electrode for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries

Abstract

To provide carboxymethyl cellulose and / or its salts capable of obtaining an electrode layer with a small electric resistance and that is used for a binding agent for an electrode of a non-aqueous electrolyte secondary battery.SOLUTION: Provided is carboxymethyl cellulose and / or its salts used for a binding agent for an electrode of a non-aqueous electrolyte secondary battery, in which a carboxymethyl substitution degree per anhydrous glucose unit is 0.5-1.2. A degree of dispersion in methanol (BS) by turbine scanning is 3-10%. A ratio of a length L to a width D (L / D) is 1.5-5.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to carboxymethyl cellulose and / or its salt used as a binder for an electrode of a non-aqueous electrolyte secondary battery, an electrode composition for a non-aqueous electrolyte secondary battery using this carboxymethyl cellulose and / or its salt, an electrode for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.

Background Art

[0002] In recent years, due to the rapid spread of small portable terminals typified by smartphones and tablets, and stationary batteries, the demand for small and high-energy density batteries to drive them has been increasing.

[0003] Generally, graphite-based materials are used for the negative electrode of lithium-ion secondary batteries. However, the theoretical capacity of graphite-based materials is 372 mAh / g (LiC6), and currently, it is approaching its limit.

[0004] Furthermore, in order to improve the energy density of lithium-ion secondary batteries, the selection of new materials is required. Therefore, materials obtained by alloying silicon, tin, etc., which have a low potential and a large specific capacity after carbon and lithium, with lithium, have attracted attention.

[0005] Among these materials, silicon can absorb up to 4.4 lithium atoms per 1 silicon atom in molar ratio, theoretically achieving about 10 times the capacity of graphite-based carbon materials. However, when silicon particles absorb lithium, their volume expands to approximately 3 to 4 times its original size, leading to degradation and a decrease in capacity due to repeated charging and discharging. Detailed analysis of this phenomenon reveals that when lithium is inserted into a silicon-containing active material, the volume expansion causes microscopic cracks to form within the electrode. Electrolyte then penetrates these cracks, forming a new film (SEI layer). This irreversible loss of capacity occurs, resulting in a decrease in battery capacity. This phenomenon manifests as changes in charge-discharge efficiency during the cycle. In particular, the decrease in cycle efficiency in the early stages of the cycle, when volume changes are large, significantly impacts the battery's lifespan when combined with a positive electrode that has high charge-discharge efficiency. Therefore, minimizing the change in electrode structure due to this volume expansion is a crucial challenge when using silicon-containing active materials.

[0006] Given this situation, Patent Document 1 attempts to improve battery characteristics by using a binder that includes three essential components: carboxymethylcellulose or its metal salt, polyacrylic acid or its metal salt, and styrene-butadiene rubber or polypyrinidene fluoride. However, according to the examples and comparative examples in Patent Document 1, when only two components (carboxymethylcellulose and styrene-butadiene rubber, or carboxymethylcellulose and polypyrinidene fluoride) were used as the binder, the desired battery characteristics were not obtained. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-198038 [Overview of the project] [Problems that the invention aims to solve]

[0008] Patent Document 1 requires three components, including carboxymethylcellulose or its metal salt, as a binder, but does not specifically mention the physical properties of carboxymethylcellulose or its metal salt. Our investigations have shown that these physical properties affect the battery characteristics, particularly the electrical resistance of the resulting electrode layer.

[0009] In other words, the object of the present invention is to provide carboxymethylcellulose and / or a salt thereof that can be used as an electrode binder for a non-aqueous electrolyte secondary battery, which can obtain an electrode layer with low electrical resistance, and to provide an electrode composition for a non-aqueous electrolyte secondary battery, an electrode for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery using this carboxymethylcellulose and / or a salt thereof. [Means for solving the problem]

[0010] As a result of diligent research, the inventors have found that the above problem can be solved by using a material having a predetermined degree of dispersion.

[0011] In other words, according to the present invention, (1) Carboxymethylcellulose and / or salts thereof used as electrode binders for non-aqueous electrolyte secondary batteries, wherein the degree of carboxymethyl substitution per anhydrous glucose unit is 0.5 to 1.2, the dispersion in methanol by turbine scan (BS) is 3 to 10%, and the ratio of length L to width D (L / D) is 1.5 to 5.0, (2) The carboxymethylcellulose and / or salt thereof as described in (1), wherein the difference between particle size D90 and particle size D10 (particle size D90 - particle size D10) is 10 to 50 μm, (3) The carboxymethylcellulose and / or salt thereof as described in (1) or (2), wherein the difference between particle size D90 and particle size D50 (particle size D90 - particle size D50) is 5 to 30 μm. (4) Carboxymethylcellulose and / or salt thereof as described in (1) or (2), wherein the difference between particle size D50 and particle size D10 (particle size D50 - particle size D10) is 5 to 20 μm. (5) Carboxymethylcellulose and / or salt thereof as described in (1) or (2), wherein the viscosity of a 1% by mass aqueous solution measured with a B-type viscometer (30 rpm) at 25°C is 1,000 to 20,000 mPa·s. (6) Two liters of a 0.3% by mass aqueous solution of carboxymethylcellulose or its salt with a dry mass m are prepared and filtered completely through a 250 mesh filter under reduced pressure conditions of -200 mmHg, and the dry mass M of the residue on the filter after filtration is measured, wherein the ratio of the dry mass M to the dry mass m is less than 200 ppm, the carboxymethylcellulose and / or its salt as described in (1) or (2), (7) An electrode composition for a non-aqueous electrolyte secondary battery comprising carboxymethylcellulose and / or a salt thereof as described in (1) or (2), and styrene-butadiene rubber having an average particle size of 50 nm to 300 nm. (8) The electrode composition for a non-aqueous electrolyte secondary battery according to (7), wherein the glass transition temperature of the styrene-butadiene rubber is -50°C to 50°C. (9) A non-aqueous electrolyte secondary battery electrode composition comprising carboxymethylcellulose and / or a salt thereof as described in (1) or (2), (10) An electrode for a non-aqueous electrolyte secondary battery using the electrode composition for a non-aqueous electrolyte secondary battery described in (7), (11) A non-aqueous electrolyte secondary battery using the electrode composition for non-aqueous electrolyte secondary batteries described in (7) It will be provided. [Effects of the Invention]

[0012] The present invention provides carboxymethylcellulose and / or a salt thereof, which can be used as an electrode binder for a non-aqueous electrolyte secondary battery, thereby enabling the acquisition of an electrode layer with low electrical resistance. Furthermore, the invention provides an electrode composition for a non-aqueous electrolyte secondary battery, an electrode for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery, all using this carboxymethylcellulose and / or a salt thereof. [Modes for carrying out the invention]

[0013] The carboxymethylcellulose and / or salt thereof of the present invention will be described below. The carboxymethylcellulose and / or salt thereof of the present invention is a carboxymethylcellulose and / or salt thereof used as an electrode binder for non-aqueous electrolyte secondary batteries, wherein the degree of carboxymethyl substitution per anhydrous glucose unit is 0.5 to 1.2, the dispersion in methanol (BS) measured by turbine scanning is 3 to 10%, and the ratio of length L to width D (L / D) is 1.5 to 5.0.

[0014] <Carboxymethylcellulose and / or its salts> The carboxymethylcellulose and / or its salt (hereinafter sometimes abbreviated as CMC) contained in the active material layer constituting the present invention has a structure in which the hydroxyl groups in the glucose units constituting cellulose are replaced with carboxymethyl ether groups. Carboxymethylcellulose may also be in the form of a salt. Examples of carboxymethylcellulose salts include metal salts such as sodium carboxymethylcellulose salt.

[0015] In this invention, cellulose refers to a polysaccharide with a structure in which D-glucopyranose (also simply called "glucose units" or "anhydrous glucose") is linked by β,1-4 bonds. Cellulose is generally classified into natural cellulose, regenerated cellulose, fine cellulose, and microcrystalline cellulose (excluding the amorphous region) based on its origin, manufacturing method, etc.

[0016] Examples of natural cellulose include bleached or unbleached pulp, refined linters, and cellulose produced by microorganisms such as acetic acid bacteria. The raw materials for bleached or unbleached pulp are not particularly limited and include, for example, wood, cotton, straw, and bamboo. The manufacturing methods for bleached or unbleached pulp are also not particularly limited and include mechanical methods, chemical methods, or methods combining mechanical and chemical methods. Examples of bleached or unbleached pulp include mechanical pulp, chemical pulp, wood pulp, sulfite pulp, kraft pulp, and papermaking pulp. In addition, examples of bleached or unbleached pulp include soluble pulp, which is chemically refined and mainly used by dissolving it in chemicals, and is a main raw material for artificial fibers and cellophane.

[0017] Examples of regenerated cellulose include regenerated cellulose obtained by dissolving cellulose in solvents such as copper-ammonia solution, cellulose xanthate solution, and morpholine derivatives, followed by re-spinning.

[0018] Examples of microcrystalline cellulose include microcrystalline cellulose obtained by depolymerizing cellulose-based materials such as natural cellulose and regenerated cellulose through acid hydrolysis, alkali hydrolysis, enzymatic hydrolysis, blasting treatment, vibration ball mill treatment, etc., and microcrystalline cellulose obtained by mechanically treating cellulose-based materials.

[0019] In producing the CMC used in the present invention, known CMC production methods can be applied. For example, after treating cellulose with a mercerizing agent (alkali) to prepare mercerized cellulose (alkali cellulose), CMC can be produced by adding an etherifying agent to the mercerized cellulose and causing an etherification reaction.

[0020] As the raw material cellulose, any of the above-mentioned celluloses can be used without particular limitation, but those with high cellulose purity are preferred, and dissolving pulp or linter is more preferred. By using these, CMC with high purity can be obtained.

[0021] Examples of the mercerizing agent include alkali metal hydroxide salts such as sodium hydroxide and potassium hydroxide. Examples of the etherifying agent include monochloroacetic acid and sodium monochloroacetate.

[0022] In the production of water-soluble carboxymethylcellulose, the molar ratio of mercerizing agent to etherifying agent (mercerizing agent / etherifying agent) is generally 2.00 to 2.45 when monochloroacetic acid is used as the etherifying agent. This is because a ratio of 2.00 or higher allows for sufficient etherification reaction, preventing the waste of unreacted monochloroacetic acid. A ratio of 2.45 or lower prevents the side reaction between excess mercerizing agent and monochloroacetic acid, which would otherwise lead to the formation of alkali metal glycolate salts, making it more economical. In this invention, CMC may be a commercially available product. An example of a commercially available product is "Sunrose," manufactured by Nippon Paper Industries Co., Ltd.

[0023] In this invention, the degree of etherification of CMC refers to the proportion of hydroxyl groups (-OH) in the glucose units constituting cellulose that are substituted with carboxymethyl ether groups (-OCH2COOH).

[0024] (Degree of substitution of carboxymethyl group) The CMC used in the present invention has a degree of substitution of carboxymethyl groups per anhydrous glucose unit (hereinafter sometimes referred to as the DS value) of 0.5 to 1.2. A DS value of 0.5 or higher ensures good solubility in water and suppresses the generation of undissolved substances. A DS value of 1.2 or lower suppresses an increase in the stringiness of the liquid and makes it easy to handle. Therefore, the DS value of the CMC of the present invention is 0.5 to 1.2, preferably 0.5 to 1.0, and more preferably 0.6 to 1.0.

[0025] The method for measuring the degree of carboxymethyl group substitution is as follows: Accurately weigh approximately 2.0 g of the sample and place it in a 300 mL stoppered Erlenmeyer flask. Add 100 mL of a solution made by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol, and shake for 3 hours to convert the carboxymethylcellulose salt (CMC) to H-CMC (hydrogen-type carboxymethylcellulose). Accurately weigh 1.5 to 2.0 g of the oven-dried H-CMC and place it in a 300 mL stoppered Erlenmeyer flask. Wet the H-CMC with 15 mL of 80% methanol, add 100 mL of 0.1 N-NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, back titrate the excess NaOH with 0.1 N-H2SO4 and calculate the degree of carboxymethyl substitution (DS value) using the following formula. A = [(100 × F' - 0.1N-H2SO4(mL) × F) × 0.1] / (Dry mass of H-CMC (g)) Degree of carboxymethyl substitution = 0.162 × A / (1 - 0.058 × A) F': Factor of N-H2SO4 F: Factor of 0.1N-NaOH

[0026] (viscosity) Furthermore, the viscosity of a 1% by mass aqueous solution of carboxymethylcellulose or its salt according to the present invention, measured at 25°C with a B-type viscometer (30 rpm), is preferably 1,000 to 20,000 mPa·s, more preferably 1,000 to 15,000 mPa·s, and even more preferably 1,000 to 10,000 mPa·s. If the viscosity is too high, there are problems such as inability to properly mix the active material and conductive additive during slurry preparation, and insufficient fluidity when coating the slurry onto the current collector, making coating impossible. If the viscosity is too low, there are problems such as the slurry flowing off the current collector when applied, making coating impossible, and migration of the active material and binders such as SBR, resulting in increased electrical resistance.

[0027] The method for measuring viscosity is as follows: Measure carboxymethylcellulose or its salt into a 1000 mL glass beaker, disperse it in 900 mL of distilled water, and prepare an aqueous dispersion with a solid content of 1% (w / v). The aqueous dispersion is stirred at 25°C using a stirrer at 600 rpm for 3 hours. Then, in accordance with the method of JIS-Z-8803, the viscosity is measured after 3 minutes at a rotation speed of 30 rpm using a Type B viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0028] (Methanol medium dispersion (BS)) The carboxymethylcellulose and / or salt thereof of the present invention has a methanol dispersion (BS) of 3 to 10%, preferably 5 to 10%, as measured by turbine scanning. When the methanol dispersion (BS) is within this range, the CMC exhibits good dispersibility when used as a binder or dispersant in the negative electrode composition, thereby improving the electrical resistance. On the other hand, if the methanol dispersion (BS) is too high, the CMC will not be uniformly dispersed in the negative electrode composition, which may worsen the electrical resistance.

[0029] Here, the methanol dispersion (BS) is obtained by measuring the backscattered light intensity (%) using a turbine scan (TURBISCAN Lab, manufactured by Eiko Seiki Co., Ltd.). Here, "BS" represents the backscattered light intensity (%). Specifically, 0.075 g of carboxymethylcellulose and 15 ml of methanol were placed in a measuring container. Then, the mixture was stirred for 10 seconds using a vortex mixer, and it was quickly set in the apparatus to start the measurement. The backscattered light intensity at a height of 20 mm after 30 minutes was calculated as the methanol dispersion (BS).

[0030] (Angle of repose) The angle of repose of carboxymethylcellulose and / or its salt in the present invention is preferably 42° or higher, and more preferably 45° or higher. If the angle of repose is too low, the powder will flow out of the feeder outlet on its own, making it impossible to dissolve a predetermined amount of carboxymethylcellulose. This reduces the function of the binder and dispersant in the negative electrode, resulting in a problem of high electrical resistance. Here, the angle of repose was measured using a powder testing device (Powder Tester PT-X (manufactured by Hosokawa Micron Corporation)) with the angle measurement method set to "Peak Operation," using a sieve with a mesh size of 710 μm and a linear diameter of 450 μm. The moisture content of the carboxymethylcellulose used in the measurement was adjusted to 6.0-9.0%.

[0031] (collapse angle) The collapse angle of carboxymethylcellulose and / or its salt in the present invention is preferably 19° or more, and more preferably 21° or more. If the collapse angle is too small, the powder will flow out of the discharge port of the feeder on its own, making it impossible to dissolve a predetermined amount of carboxymethylcellulose. This reduces the function of the binder and dispersant in the negative electrode, resulting in a problem of high electrical resistance. Here, the collapse angle was measured using a powder testing device (Powder Tester PT-X (manufactured by Hosokawa Micron Corporation)) with the angle measurement method set to "Peak Operation," using a sieve with a mesh size of 710 μm and a linear diameter of 450 μm. The moisture content of the carboxymethylcellulose used in the measurement was adjusted to 6.0-9.0%. (difference angle) Furthermore, the value obtained by subtracting the collapse angle from the angle of repose can be expressed as the difference angle.

[0032] (Amount of filtration residue) Furthermore, it is preferable that the amount of filtration residue of the carboxymethylcellulose and / or salt thereof of the present invention is within a predetermined range. That is, when 2 liters of a 0.3% by mass aqueous solution of carboxymethylcellulose or its salt with a dry mass m is prepared and completely filtered through a 250 mesh filter under reduced pressure conditions of -200 mmHg, and the dry mass M of the residue on the filter after filtration is measured, it is preferable that the ratio of the dry mass M to the dry mass m is less than 200 ppm, and more preferably less than 50 ppm. If this value is too high, the electrode slurry is more likely to clog when filtered, and the amount of carboxymethylcellulose in the filtered slurry will be less than the predetermined amount. This reduces its function as a binder and dispersant, resulting in a problem of increased electrical resistance.

[0033] (Particle size) The value obtained by subtracting the particle size D10 from the particle size D90 of the carboxymethylcellulose and / or its salt in the present invention (particle size D90 - particle size D10) is preferably 10 to 50 μm, more preferably 10 to 30 μm, and even more preferably 20 to 30 μm. If this value is too large, the particles will separate into layers, resulting in a solution that is not homogeneous and has high electrical resistance.

[0034] Furthermore, the value obtained by subtracting the particle size D50 from the particle size D90 of the carboxymethylcellulose and / or its salt in the present invention (particle size D90 - particle size D50) is preferably 5 to 30 μm, more preferably 10 to 30 μm, and even more preferably 10 to 20 μm. If this value is too large, the particles will separate into layers, resulting in a solution that is not homogeneous and has high electrical resistance.

[0035] Furthermore, the value obtained by subtracting the particle size D10 from the particle size D50 of the carboxymethylcellulose and / or its salt in the present invention (particle size D50 - particle size D10) is preferably 5 to 20 μm, more preferably 5 to 15 μm, and even more preferably 8 to 12 μm. If this value is too large, the particles will separate into layers, resulting in a problem where a uniform solution cannot be obtained.

[0036] Here, D10 is the particle size that accounts for 10% of the volume-average particle size distribution when accumulated from the minimum value, D50 is the particle size that accounts for 50% of the volume-average particle size distribution and is also called the average particle size. D90 is the particle size that accounts for 90% of the volume-average particle size distribution. The particle size distribution based on volume-average particle size can be measured, for example, using methanol as a dispersant and a laser diffraction / scattering particle size analyzer.

[0037] Furthermore, the particle size D10 of the carboxymethylcellulose and / or its salt in the present invention is preferably 1 to 10 μm, the particle size D50 is preferably 10 to 20 μm, and the particle size D90 is preferably 20 to 40 μm.

[0038] The particle size distribution sharpness of carboxymethylcellulose and / or its salt according to the present invention is a value calculated from the following formula. [Formula 1] Particle size distribution sharpness = [(D50 / D10)+(D90 / D50)] / 2 In this invention, the particle size distribution sharpness is preferably 2.8 to 5.0, and more preferably 3.0 to 4.0. If this value is too small, when mixing and stirring powdered CMC or other negative electrode materials with water to prepare a slurry, the CMC will not dissolve sufficiently, resulting in reduced adhesion between the active materials and increased resistance.

[0039] Furthermore, the L / D ratio of the carboxymethylcellulose and / or salt of the present invention is preferably 1.5 to 5.0, more preferably 1.7 to 4.0, and even more preferably 2.0 to 3.0. Here, L represents the length of the carboxymethylcellulose and / or salt, and D represents the width of the carboxymethylcellulose and / or salt. In addition, L and D are the average of the lengths and widths of 50 carboxymethylcellulose and / or salts observed, for example, by scanning electron microscopy, and L / D is the average value of the L / D ratio of the 50 carboxymethylcellulose and / or salts.

[0040] The BET specific surface area of ​​carboxymethylcellulose and / or its salts in this invention is 0.5 to 5.0 m². 2 / g is preferred, and 1.0 to 4.0 m 2 / g is more preferable, 1.5 to 3.0 m 2 A value of / g is even more preferable. If this value is too small, water will not penetrate the interior of the CMC easily, increasing the amount of undissolved CMC, which will reduce the adhesion between active materials and increase resistance. The BET specific surface area was measured by weighing 0.1 g of powdered CMC into a test tube, drying it at 105°C for 1 hour while blowing nitrogen gas using a FlowPrep060 from Micromeritics, and then measuring the BET specific surface area using a Gemini VII2390 from Shimadzu Corporation.

[0041] [Crushing process] In the present invention, carboxymethylcellulose or its salt may be subjected to fine grinding treatment. As for the method of fine grinding carboxymethylcellulose or its salt, either a dry grinding method, in which it is processed in a powder state, or a wet grinding method, in which it is processed while dispersed or dissolved in a liquid, may be selected.

[0042] By mechanically dry or wet grinding carboxymethylcellulose or its salts, gel particles derived from carboxymethylcellulose or its salts that exist as undissolved matter in aqueous solutions are refined. As a result, it is believed that coarse undissolved matter that causes streaks, peeling, pinholes, etc. on the surface of the negative electrode can be suppressed.

[0043] Examples of fine grinding devices that can be used in this invention include the following: Dry grinders include cutting mills, impact mills, and airflow mills. These can be used individually or in combination, and even multiple stages of processing can be performed with the same machine.

[0044] Examples of cutting mills include mesh mills (manufactured by Horai Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuma Seisakusho Co., Ltd.), knife mills (manufactured by Parman Co., Ltd.), granulators (manufactured by Herboldt Co., Ltd.), and rotary cutter mills (manufactured by Nara Machinery Works Co., Ltd.).

[0045] Examples of impact mills include the pulperizer (manufactured by Hosokawa Micron Corporation), the fine impact mill (manufactured by Hosokawa Micron Corporation), the super micron mill (manufactured by Hosokawa Micron Corporation), the sample mill (manufactured by Seishin Co., Ltd.), the bantam mill (manufactured by Seishin Co., Ltd.), the atomizer (manufactured by Seishin Co., Ltd.), the tornado mill (Nikkiso Co., Ltd.), the turbo mill (Turbo Kogyo Co., Ltd.), and the bevel impactor (Aikawa Iron Works Co., Ltd.).

[0046] Examples of airflow mills include the CGS type jet mill (manufactured by Mitsui Mining Co., Ltd.), the Jet Mill (manufactured by Sansho Industry Co., Ltd.), the Ebara Jet Micronizer (manufactured by Ebara Corporation), the Selenium Mirror (manufactured by Masuko Sangyo Co., Ltd.), and the Supersonic Jet Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.). Examples of media mills include vibrating ball mills.

[0047] Examples of wet grinders include the Mascolloider (manufactured by Masuko Sangyo Co., Ltd.), and examples of media mills include the bead mill (manufactured by AIMEX Co., Ltd.) and the high-pressure homogenizer (manufactured by Sanmaru Machinery Industry Co., Ltd.).

[0048] In the present invention, a step may be provided in which carboxymethylcellulose or a salt thereof that has undergone fine grinding treatment is classified based on the particle size. The above classification process may be implemented during or after the fine grinding process. Any known method may be used for classification. Examples of dry classifiers include cyclone classifiers, DS separators, turboclassifiers, microseparators, and air separators. On the other hand, examples of wet classifiers include liquid cyclone systems, centrifugal sedimentation machines, and hydroseparators.

[0049] The CMC used in the present invention may be one type, or a combination of two or more CMCs with different degrees of etherification, DS values, viscosity, molecular weight, etc.

[0050] <Binding agent for non-aqueous electrolyte secondary batteries> The carboxymethylcellulose and / or salt thereof of the present invention is used as an electrode binder for non-aqueous electrolyte secondary batteries. Typically, an aqueous solution containing carboxymethylcellulose and / or a salt thereof is used as an electrode binder for non-aqueous electrolyte secondary batteries.

[0051] In an aqueous solution of carboxymethylcellulose and / or its salt, the concentration of carboxymethylcellulose or its salt is usually 0.1 to 10% by mass, preferably 0.2 to 4% by mass, and more preferably 0.5 to 2% by mass.

[0052] There are no particular restrictions on the production conditions for aqueous solutions of carboxymethylcellulose and / or its salts. For example, carboxymethylcellulose and / or its salts can be prepared by adding them to water (e.g., distilled water, purified water, tap water, etc.) and dissolving them by stirring as necessary.

[0053] Furthermore, binders for non-aqueous electrolyte secondary batteries may include carboxymethylcellulose and / or its salts, as well as other binders. Examples of binders used in the negative electrode composition include synthetic rubber binders. One or more synthetic rubber binders can be selected from the group consisting of styrene-butadiene rubber (SBR), nitrile-butadiene rubber, methyl methacrylate-butadiene rubber, chloroprene rubber, carboxy-modified styrene-butadiene rubber, and latexes of these synthetic rubbers. Of these, styrene-butadiene rubber (SBR) is preferred. In addition, examples of binders used in the positive electrode composition include the synthetic rubber binders mentioned above for the negative electrode, as well as polytetrafluoroethylene (PTFE).

[0054] Here, the average particle size (D50) of the SBR is preferably 50 to 300 nm, and more preferably 50 to 200 nm. If the average particle size (D50) of the SBR is too large, the SBR will not adhere uniformly to the active material, reducing its binder function and resulting in high electrical resistance. If it is too small, the SBR will cover the active material, also resulting in high electrical resistance.

[0055] Furthermore, the glass transition temperature (Tg) of SBR is preferably -50°C to 50°C. When SBR is within the above range, it mixes well with the carboxymethylcellulose and / or its salts of the present invention and has appropriate flexibility when used as a negative electrode layer, so that the electrical resistance does not tend to increase.

[0056] <Electrode composition for nonaqueous electrolyte secondary batteries> The electrode composition for non-aqueous electrolyte secondary batteries of the present invention (hereinafter sometimes referred to as "electrode composition") comprises at least an electrode active material and the carboxymethylcellulose and / or salt thereof of the present invention as a binder for non-aqueous electrolyte secondary batteries.

[0057] In other words, the carboxymethylcellulose and / or salt thereof of the present invention can be used as an electrode binder and constitute an electrode composition together with an electrode active material. In this case, the content of carboxymethylcellulose and / or salt thereof in the electrode composition is preferably 0.1 to 4.0% by mass of the total electrode composition.

[0058] Furthermore, when using the other binders mentioned above, the content of the non-aqueous electrolyte secondary battery binder in the electrode composition is preferably 1 to 10% by mass, more preferably 1 to 6% by mass, and even more preferably 1 to 2% by mass.

[0059] (electrode active material) The electrode active material contained in the active material layer constituting the present invention is a negative electrode active material when the electrode for a non-aqueous electrolyte secondary battery is a negative electrode electrode, and a positive electrode active material when it is a positive electrode electrode.

[0060] As the negative electrode active material, graphite materials such as graphite (natural graphite, artificial graphite, etc.), coke, and carbon fiber; elements capable of forming an alloy with lithium, that is, for example, elements such as silicon-based compounds, Al, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Ti, etc.; compounds containing elements capable of forming an alloy with lithium; composites of elements capable of forming an alloy with lithium and the said compounds, and carbon and / or the graphite material, or nitrides containing lithium, etc. can be exemplified. Among these, graphite materials and silicon-based compounds are preferable, and silicon particles or silicon oxide particles are more preferable as the graphite and silicon-based compounds.

[0061] Note that the silicon oxide in the present invention means SiO x (represented by 0 < x ≦ 2). Also, in the present invention, as the active material layer, a composite of a silicon-based compound and a graphite material is more suitable.

[0062] When the negative electrode active material is a composite of a graphite material and a silicon-based compound, the mixing ratio of the graphite material:silicon-based compound is preferably 10:90 to 90:10, and more preferably 50:50 to 80:20.

[0063] As the positive electrode active material, LiFePO4, LiMe x O y (Me means a transition metal containing at least one of Ni, Co, and Mn. x and y mean arbitrary numbers.) - based positive electrode active materials are preferable.

[0064] The content of the electrode active material in the electrode layer is usually 90 to 99% by mass, preferably 91 to 99% by mass, more preferably 92 to 99% by mass, further preferably 95 to 99% by mass, particularly preferably 96 to 99% by weight, and most preferably 98 to 99% by mass.

[0065] Furthermore, the electrode composition may contain a conductive additive as needed. Examples of conductive additives include conductive carbons such as carbon black, acetylene black, and Ketjenblack. The content of the conductive additive in the electrode composition is usually 0.01 to 20% by mass, preferably 0.1 to 10% by mass.

[0066] Furthermore, an aqueous solvent is preferred as the solvent used in the electrode composition. The type of aqueous solvent is not particularly limited, but it is preferably water, a water-soluble organic solvent, or a mixture thereof, with water being more preferred.

[0067] Water-soluble organic solvents are organic solvents that dissolve in water. Examples include methanol, ethanol, 2-propanol, butanol, glycerin, acetone, methyl ethyl ketone, 1,4-dioxane, N-methyl-2-pyrrolidone, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide, dimethyl sulfoxide (DMSO), acetonitrile, methyl triglycol diester succinate, acetic acid, and combinations thereof.

[0068] When the above mixed solvent is used as the aqueous solvent, the amount of water-soluble organic solvent in the mixed solvent is preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. There is no upper limit to this amount, but it is preferably 95% by mass or less, and more preferably 90% by mass or less. Furthermore, the aqueous solvent may also contain water-insoluble organic solvents as long as the effects of the invention are not impaired.

[0069] There are no particular limitations on the manufacturing conditions of the electrode composition. For example, other components constituting the electrode composition are added to an aqueous solution of carboxymethylcellulose and / or its salt and mixed while stirring as necessary. Furthermore, the properties of the electrode composition are not particularly limited. For example, it may be liquid, paste, or slurry, and any of these may be used.

[0070] <Non-aqueous electrolyte secondary battery electrode> An electrode layer can be formed on a current collector by applying the above electrode composition onto the current collector. Examples of application methods include blade coating, bar coating, and die coating, with blade coating being preferred. For example, in the case of blade coating, a method of casting the electrode composition onto the current collector using a coating device such as a doctor blade is exemplified. Furthermore, the method of lamination is not limited to the above specific example, and a method of applying the electrode composition by discharging it from an extrusion-type injector having a slot nozzle onto a current collector that is wound around a backup roll and running is also exemplified. In blade coating, after casting, the electrode layer can be obtained by further drying as needed by heating (for example, at a temperature of 80 to 120°C, for a heating time of 4 to 12 hours) and pressurizing by a roll press or the like.

[0071] The shape of the electrode for the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, but it is usually in the form of a sheet. In the case of a sheet-shaped electrode plate, the thickness (thickness of the electrode layer formed from the electrode composition, excluding the current collector portion) is difficult to specify as it depends on the composition of the composition and manufacturing conditions, but it is usually 30 to 150 μm.

[0072] (Current collector) Any electrical conductor that does not cause a fatal chemical change in the constituent electrodes or battery can be used as the current collector. A negative electrode current collector can be used when the electrode is negative, and a positive electrode current collector can be used when the electrode is positive.

[0073] Examples of materials for the negative electrode current collector include stainless steel, nickel, copper, titanium, carbon, copper, or stainless steel with carbon, nickel, titanium, or silver deposited on its surface. Of these, copper or copper alloys are preferred, and copper is more preferred. Examples of materials for the positive electrode current collector include metals such as aluminum and stainless steel, with aluminum being preferred. Examples of current collector shapes include mesh, punched metal, formed metal, and foil processed into a plate shape, with foil processed into a plate shape being preferred. <Nonaqueous electrolyte secondary battery> The electrode for a non-aqueous electrolyte secondary battery of the present invention is used as an electrode in a non-aqueous electrolyte secondary battery.

[0074] In other words, the present invention also provides a non-aqueous electrolyte secondary battery. A non-aqueous electrolyte secondary battery can have a structure in which positive and negative electrodes are alternately stacked with a separator in between and wound many times. Furthermore, a non-aqueous electrolyte secondary battery can be obtained by placing the stack of positive electrode, separator, and negative electrode wound many times into a battery container, injecting a non-aqueous electrolyte, and sealing the container.

[0075] The shape of the non-aqueous electrolyte secondary battery is not particularly limited, and cylindrical, rectangular, flat, coin-shaped, button-shaped, sheet-shaped, etc., can be used. Furthermore, the material of the battery container is not particularly limited as long as it can achieve the purpose of preventing moisture from entering the inside of the battery, and examples include metal, aluminum laminate, etc.

[0076] The separator is typically impregnated with a non-aqueous electrolyte. For example, a microporous membrane or nonwoven fabric made of polyolefin such as polyethylene or polypropylene can be used as the separator.

[0077] Non-aqueous electrolytes typically consist of a lithium salt and a non-aqueous solvent. Examples of lithium salts include LiPF6, LiAsF6, LiBF4, and LiClO4. Examples of non-aqueous solvents include ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, butylene carbonate, and methyl ethyl carbonate. Non-aqueous solvents may be used individually or in combination of two or more. The concentration of the lithium salt in the non-aqueous electrolyte is typically 0.5 to 2.5 mol / L.

[0078] Electrodes for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries produced using the electrode composition of the present invention, which uses carboxymethylcellulose and / or its salt as an electrode binder for non-aqueous electrolyte secondary batteries, have low resistance values ​​and excellent battery characteristics due to the small amount of undissolved gel. [Examples]

[0079] The embodiments of the present invention will be described below with reference to examples, but the present invention is not limited thereto. <Measurement Method and Evaluation Method> In the examples and comparative examples, measurements and evaluations were performed as follows.

[0080] (Measurement of carboxymethyl substitution degree (DS value)) Approximately 2.0 g of the sample was accurately weighed and placed in a 300 mL stoppered Erlenmeyer flask. 100 mL of a solution of 1000 mL of methanol and 100 mL of special grade concentrated nitric acid was added, and the mixture was shaken for 3 hours to convert the carboxymethylcellulose salt (CMC) to H-CMC (hydrogen-type carboxymethylcellulose). 1.5 to 2.0 g of the oven-dried H-CMC was accurately weighed and placed in a 300 mL stoppered Erlenmeyer flask. The H-CMC was moistened with 15 mL of 80% methanol, 100 mL of 0.1N-NaOH was added, and the mixture was shaken at room temperature for 3 hours. Using phenolphthalein as an indicator, the excess NaOH was back-titrated with 0.1N-H2SO4, and the degree of carboxymethyl substitution (DS value) was calculated using the following formula. A = [(100 × F' - 0.1N-H2SO4(mL) × F) × 0.1] / (Dry mass of H-CMC (g)) Degree of carboxymethyl substitution = 0.162 × A / (1 - 0.058 × A) F': Factor of N-H2SO4 F: Factor of 0.1N-NaOH

[0081] (Measurement of 1% by mass viscosity of CMC) Carboxymethylcellulose or its salt was measured into a 1000 mL glass beaker and dispersed in 900 mL of distilled water to prepare an aqueous dispersion with a solid content of 1% (w / v). The aqueous dispersion was stirred at 25°C using a stirrer at 600 rpm for 3 hours. Then, in accordance with the method of JIS-Z-8803, the viscosity was measured after 3 minutes at a rotation speed of 30 rpm using a Type B viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0082] (Particle size) The particle sizes D10, D50, and D90 of carboxymethylcellulose or its salts used in the examples and comparative examples were determined from the particle size distribution based on the volume-average particle size.

[0083] The particle size distribution was measured using a laser diffraction / scattering particle size analyzer (Mastersizer 2000E, manufactured by Spectris Co., Ltd.). For the measurement, the sample was dispersed in methanol and then subjected to sonication for at least 1 minute. The particle size distribution sharpness was calculated using the following formula based on the values ​​obtained by the above method. Particle size distribution sharpness = [(D50 / D10)+(D90 / D50)] / 2

[0084] (Methanol medium dispersion (BS)) The methanol dispersion (BS) of carboxymethylcellulose or its salts used in the examples and comparative examples was measured by backscatter light intensity (%) using a turbine scan (TURBISCAN Lab, manufactured by Eiko Seiki Co., Ltd.). Specifically, 0.075 g of carboxymethylcellulose and 15 ml of methanol were placed in a measuring container. The mixture was then stirred for 10 seconds using a vortex mixer, and the container was quickly set in the apparatus to start the measurement. The backscatter light intensity at a height of 20 mm after 30 minutes was calculated as the methanol dispersion (BS).

[0085] (Angle of repose) The angles of repose of carboxymethylcellulose or its salts used in the examples and comparative examples were measured using a powder tester (Powder Tester PT-X, manufactured by Hosokawa Micron Corporation). Specifically, the angle was measured using a powder property tester (Powder Tester PT-X (manufactured by Hosokawa Micron Corporation)) with the angle measurement method set to "Peak Operation," using a sieve with a mesh size of 710 μm and a linearity of 450 μm. The moisture content of the carboxymethylcellulose used for measurement was adjusted to 6.0-9.0%.

[0086] (collapse angle) The collapse angles of carboxymethylcellulose or its salts used in the examples and comparative examples were measured using a powder tester (Powder Tester PT-X, manufactured by Hosokawa Micron Corporation) under conditions equivalent to those used for measuring the angle of repose described above. (difference angle) Using the angle of repose and collapse angle measured above, the difference angle is Difference angle = angle of repose - angle of collapse This was determined by [method / method].

[0087] (L / D) The length L and width D of carboxymethylcellulose or its salts used in the examples and comparative examples were measured, and the L / D ratio was determined. Here, L and D were defined as the average of the lengths and widths of 50 carboxymethylcellulose and / or its salts observed, for example, by scanning electron microscopy, and L / D was defined as the average L / D ratio of the 50 carboxymethylcellulose and / or its salts.

[0088] (BET specific surface area) 0.1 g of powdered CMC was weighed into a test tube, dried at 105°C for 1 hour while blowing nitrogen gas using a FlowPrep060 from Micromeritics, and the BET specific surface area was measured using a Gemini VII2390 from Shimadzu Corporation.

[0089] (Impedance) The electrode compositions obtained in the examples and comparative examples were coated onto a current collector (copper foil measuring 320 mm in length, 170 mm in width, and 17 μm in thickness (manufactured by Furukawa Electric Co., Ltd., NC-WS)), dried at room temperature for 30 minutes, and then dried at 60°C for 30 minutes. After drying, a negative electrode plate having a negative electrode active material layer was obtained by pressing with 5.0 kN using a small tabletop roll press (manufactured by Tester Sangyo Co., Ltd., SA-602) on the current collector. The obtained negative electrode plate and a LiCoO2 positive electrode plate (manufactured by Hosen Co., Ltd., basis weight: 227.1 g / m²) were used. 2Each negative electrode plate (effective discharge capacity: 145 mAh / g) was punched out into a circle with a diameter of 16 mm, and the punched-out negative electrode plate and positive electrode plate were vacuum-dried at 120°C for 12 hours. Similarly, a separator (CS Tech, 20 μm thick polypropylene separator) was punched out into a circle with a diameter of 17 mm and vacuum-dried at 60°C for 12 hours. Then, the negative electrode plate was placed in a 20.0 mm diameter stainless steel circular dish-shaped container, and then the separator, positive electrode plate, spacer (15.5 mm diameter, 1 mm thick), and stainless steel washer (Hosen Co., Ltd.) were stacked in this order. After that, 300 μL of electrolyte (1 mol / L LiPF6, ethylene carbonate to diethyl carbonate volume ratio 1:1) was added to the circular dish-shaped container. A stainless steel cap was placed over this via a polypropylene packing, and it was sealed with a coin cell crimping machine (Hosen Co., Ltd.) to obtain a coin-type non-aqueous electrolyte secondary battery. The obtained coin-type batteries were subjected to one charge-discharge cycle using a secondary battery charge-discharge test apparatus (BTS2004, manufactured by Nagano Corporation) in a constant temperature chamber at 25°C, with charging followed by discharging. Next, impedance measurements were performed using an impedance tester (VPS, manufactured by Toyo Technica Corporation), and the resistance value was calculated using ZView (manufactured by Scribner Associates). A smaller resistance value indicates that a non-aqueous electrolyte battery with better performance when used as a battery can be obtained.

[0090] (Measurement of the amount of filtration residue of carboxymethylcellulose or its salts) Two liters of a 0.3% by mass aqueous solution of carboxymethylcellulose or its salt (based on the dry mass of carboxymethylcellulose or its salt) were prepared. Two liters of this aqueous solution were filtered under reduced pressure of -200 mmHg using a filter ("Separote," manufactured by Kiriyama Seisakusho) through a 250-mesh filter (stainless steel, mesh size 63 μm). The residue remaining on the 250-mesh filter was air-dried at 105°C for 16 hours, and the mass of the dried residue was measured and expressed as a mass percentage (ppm) relative to the mass of carboxymethylcellulose in the aqueous carboxymethylcellulose solution. The measurement and evaluation results described above are shown in Table 1.

[0091] <Preparation of Electrode Composition> (Example 1) <Production of CMC> To a twin-screw kneader with the rotation speed adjusted to 100 rpm, 550 parts of isopropanol and a solution of 40 parts of sodium hydroxide dissolved in 80 parts of water were added, and 100 parts were charged based on the dry weight when the lint pulp was dried at 100 °C for 60 minutes. Stirring and mixing were carried out at 30 °C for 90 minutes to prepare mercerized cellulose. While further stirring, 50 parts of monochloroacetic acid was added, and after stirring for 30 minutes, the temperature was raised to 70 °C and a carboxymethylation reaction was carried out for 90 minutes. After the reaction was completed, it was neutralized with acetic acid to a pH of about 7, de-liquored, dried, and pulverized to obtain CMC1. The DS value of CMC1 was 0.92, and the 1% viscosity was 1650 mPa·s. <Production of Electrode Composition> As the negative electrode active material, 1.0 g of 98% by mass graphite powder and 1.0 g of 98% by mass SiO x powder, 0.01 g of 98% by mass acetylene black as a conductive assistant, 1.0 g of an aqueous dispersion (2% by mass) of CMC1 as a binder, 63 mg of 48% by mass styrene-butadiene rubber (SBR), and 1.5 g of water were mixed with a Magels star (manufactured by Kurashiki Boseki Co., Ltd., Magels star KK-250S) to prepare an electrode composition. The Tg of SBR was 7 °C, and the average particle diameter was 165 nm.

[0092] (Example 2) <Production of CMC> To a twin-screw kneader with the rotation speed adjusted to 100 rpm, 650 parts of isopropanol and a solution of 60 parts of sodium hydroxide dissolved in 100 parts of water were added, and 100 parts were charged based on the dry weight when the lint pulp was dried at 100 °C for 60 minutes. Stirring and mixing were carried out at 30 °C for 90 minutes to prepare mercerized cellulose. While further stirring, 70 parts of monochloroacetic acid was added, and after stirring for 30 minutes, the temperature was raised to 70 °C and a carboxymethylation reaction was carried out for 90 minutes. After the reaction was completed, it was neutralized with acetic acid to a pH of about 7, de-liquored, dried, and pulverized to obtain CMC2. The DS value of CMC2 was 0.84, and the 1% viscosity was 4580 mPa·s. <Production of Electrode Composition> The electrode composition was prepared in the same manner as in Example 1, except that the type of CMC was changed to CMC2 obtained above.

[0093] (Example 3) <Manufacture of CMC> 600 parts of isopropanol and a solution of 55 parts of sodium hydroxide dissolved in 100 parts of water were added to a twin-screw kneader with the rotation speed adjusted to 100 rpm, and 100 parts were charged based on the dry weight when the lint pulp was dried at 100 °C for 60 minutes. It was stirred and mixed at 30 °C for 90 minutes to prepare mercerized cellulose. While further stirring, 65 parts of monochloroacetic acid was added, and after stirring for 30 minutes, the temperature was raised to 70 °C and a carboxymethylation reaction was carried out for 90 minutes. After the reaction was completed, it was neutralized with acetic acid to a pH of about 7, de-liquored, dried, and pulverized to obtain CMC3. The DS value of CMC3 was 0.70, and the 1% viscosity was 4900 mPa·s. <Manufacture of electrode composition> The electrode composition was prepared in the same manner as in Example 1, except that the type of CMC was changed to CMC3 obtained above.

[0094] (Example 4) <Manufacture of CMC> 600 parts of isopropanol and a solution of 38 parts of sodium hydroxide dissolved in 80 parts of water were added to a twin-screw kneader with the rotation speed adjusted to 100 rpm, and 100 parts were charged based on the dry weight when the lint pulp was dried at 100 °C for 60 minutes. It was stirred and mixed at 30 °C for 90 minutes to prepare mercerized cellulose. While further stirring, 46 parts of monochloroacetic acid was added, and after stirring for 30 minutes, the temperature was raised to 70 °C and a carboxymethylation reaction was carried out for 90 minutes. After the reaction was completed, it was neutralized with acetic acid to a pH of about 7, de-liquored, dried, and pulverized to obtain CMC4. The DS value of CMC4 was 0.70, and the 1% viscosity was 8980 mPa·s. <Manufacture of electrode composition> The electrode composition was prepared in the same manner as in Example 1, except that the type of CMC was changed to CMC4 obtained above.

[0095] (Comparative Example 1) <Manufacture of electrode composition> The electrode composition was prepared in the same manner as in Example 1, except that the type of CMC was changed to CMC5 with a DS value of 0.93 and a 1% viscosity of 3460 mPa·s.

[0096] (Comparative Example 2) <Manufacture of electrode composition> The electrode composition was prepared in the same manner as in Example 1, except that the type of CMC was changed to CMC6 with a DS value of 0.69 and a 1% viscosity of 6340 mPa·S.

[0097] (Comparative Example 3) <Treatment of CMC> CMC7 (DS value 0.68, viscosity 1650 mPa·s) was pulverized with a ball mill and classified with a 400 mesh. For this CMC7, the degree of dispersion in methanol (BS) and L / D were measured. Note that the electrode composition was not prepared.

[0098]

Table 1

[0099] As shown in Table 1, a carboxymethyl cellulose and / or a salt thereof used as a binder for an electrode of a non-aqueous electrolyte secondary battery, having a carboxymethyl substitution degree per anhydroglucose unit of 0.5 to 1.2, a degree of dispersion in methanol (BS) by turbiscan of 3 to 10%, and a ratio of length L to width D (L / D) of 1.5 to 5.0, the electrode layer obtained from the electrode composition using the binder for the electrode has a low resistance value, and it was shown that the battery performance is good when used as a non-aqueous electrolyte secondary battery.

Claims

1. Carboxymethylcellulose and / or its salts, used as electrode binders for non-aqueous electrolyte secondary batteries, wherein the degree of carboxymethyl substitution per anhydrous glucose unit is 0.5 to 1.2, the dispersion in methanol (BS) by turbine scan is 3 to 10%, and the ratio of length L to width D (L / D) is 1.5 to 5.

0.

2. The carboxymethylcellulose and / or salt thereof according to claim 1, wherein the difference between particle size D90 and particle size D10 (particle size D90 - particle size D10) is 10 to 50 μm.

3. The carboxymethylcellulose and / or salt thereof according to claim 1 or 2, wherein the difference between particle size D90 and particle size D50 (particle size D90 - particle size D50) is 5 to 30 μm.

4. The carboxymethylcellulose and / or salt thereof according to claim 1 or 2, wherein the difference between particle size D50 and particle size D10 (particle size D50 - particle size D10) is 5 to 20 μm.

5. The carboxymethylcellulose and / or salt thereof according to claim 1 or 2, wherein the viscosity of a 1% by mass aqueous solution, measured at 25°C with a B-type viscometer (30 rpm), is 1,000 to 20,000 mPa·s.

6. The carboxymethylcellulose and / or salt thereof according to claim 1 or 2, wherein two liters of a 0.3% by mass aqueous solution of carboxymethylcellulose or a salt thereof with a dry mass m are prepared, and the entire solution is filtered through a 250-mesh filter under reduced pressure conditions of -200 mmHg, and the dry mass M of the residue on the filter after filtration is measured, and the ratio of the dry mass M to the dry mass m is less than 200 ppm.

7. An electrode composition for a non-aqueous electrolyte secondary battery comprising carboxymethylcellulose and / or a salt thereof according to claim 1 or 2, and styrene-butadiene rubber having an average particle size of 50 nm to 300 nm.

8. The electrode composition for a non-aqueous electrolyte secondary battery according to claim 7, wherein the glass transition temperature of the styrene-butadiene rubber is -50°C to 50°C.

9. A non-aqueous electrolyte secondary battery electrode composition comprising carboxymethylcellulose and / or a salt thereof according to claim 1 or 2.

10. An electrode for a non-aqueous electrolyte secondary battery, using the electrode composition for a non-aqueous electrolyte secondary battery described in claim 6.

11. A non-aqueous electrolyte secondary battery using the electrode composition for a non-aqueous electrolyte secondary battery described in claim 7.

Images