Method for producing carboxymethyl cellulose lithium salt, method for producing electrode composition for non-aqueous electrolyte secondary battery, method for producing electrode for non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery

Abstract

To provide a method for producing a carboxymethylcellulose lithium salt, by which the carboxymethylcellulose lithium salt capable of giving a battery having a large battery capacity and an excellent capacity retention when used in a nonaqueous electrolyte secondary battery can be produced at a low cost.SOLUTION: And step (B) of reacting the mercerized cellulose with a carboxymethylation agent in a mixed solution containing 50 to 99% by mass of organic solvents relative to the sum of water and the organic solvents to obtain carboxymethyl cellulose, wherein the amount of lithium ions contained in the carboxymethyl cellulose lithium salt 1g is 30000 to 50, 000ppm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a lithium carboxymethyl cellulose salt, a method for producing an electrode composition for a non-aqueous electrolyte secondary battery, a method for producing an electrode for a non-aqueous electrolyte secondary battery, and a method for producing a non-aqueous electrolyte secondary battery. [Background technology]

[0002] In recent years, the rapid spread of small portable devices such as smartphones and tablets, as well as stationary storage batteries, has led to an increasing demand for small, high-energy-density batteries to power them.

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

[0004] Furthermore, in order to improve the energy density of lithium-ion secondary batteries, it is necessary to select new materials. Therefore, materials made by alloying lithium with silicon, tin, etc., which have the second lowest potential and large specific capacity after carbon and lithium, are attracting attention.

[0005] Among these materials, silicon can absorb up to 4.4 lithium atoms per 1 silicon atom in molar ratio, theoretically providing approximately 10 times the capacity of graphite-based carbon materials. However, silicon particles expand in volume approximately three to four times when they absorb lithium, leading to degradation and capacity loss with repeated charge-discharge cycles. Detailed analysis of this phenomenon has revealed that when lithium is inserted into silicon-containing active materials, the volume expansion causes microcracks to form within the electrode, allowing the electrolyte to penetrate these microcracks and form a new coating (SEI layer). This creates irreversible capacity loss, resulting in a decrease in battery capacity. This phenomenon manifests itself in changes in charge-discharge efficiency during cycling. The decrease in cycle efficiency, especially during the early stages of cycling when volume change is large, significantly impacts the battery's lifespan when combined with a positive electrode with high charge-discharge efficiency. Therefore, minimizing changes in electrode structure due to this volume expansion is a key challenge when using silicon-containing active materials.

[0006] In view of these circumstances, Patent Document 1 aims to improve battery characteristics by using a binder containing three essential components: carboxymethyl cellulose or a metal salt thereof, polyacrylic acid or a metal salt thereof, and styrene-butadiene rubber or polyvinylidene fluoride. However, according to the examples and comparative examples of Patent Document 1, when only two components (carboxymethyl cellulose and styrene-butadiene rubber, or carboxymethyl cellulose and polyvinylidene fluoride) were used as the binder, desired battery characteristics were not obtained.

[0007] Furthermore, since the ions involved in charging and discharging in lithium ion secondary batteries are lithium ions, and the presence of other metal ions may degrade battery characteristics, the use of carboxymethylcellulose lithium salt as a metal salt of carboxymethylcellulose has also been considered (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-198038 [Patent Document 2] Japanese Patent Publication No. 2023-8785 Summary of the Invention [Problem to be solved by the invention]

[0009] Patent Document 2 describes a method for preparing a lithium salt of carboxymethyl cellulose, in which cellulose is mercerized (alkalized) using sodium hydroxide, and the sodium salt of carboxymethyl cellulose (CMC-Na) obtained by etherifying the mercerized cellulose is converted into CMC-H in an acidic state, and then a substitution reaction is carried out using a lithium salt-ethanol solution to obtain the lithium salt of carboxymethyl cellulose.

[0010] However, the method of Patent Document 2 involves many complicated steps and is costly.

[0011] An object of the present invention is to provide a method for producing, at low cost, a carboxymethyl cellulose lithium salt that, when used in a non-aqueous electrolyte secondary battery, can provide a battery with a large battery capacity and an excellent capacity retention rate. [Means for solving the problem]

[0012] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a specific procedure.

[0013] The present invention provides the following: (1) A method for producing a lithium carboxymethyl cellulose salt having a degree of carboxymethyl substitution per anhydroglucose unit of 0.5 to 2.0, comprising: step (A): treating cellulose with lithium hydroxide in a solvent containing 20% ​​by mass or more of water to obtain mercerized cellulose; and step (B): reacting the mercerized cellulose with a carboxymethylating agent in a mixed solvent containing 50 to 99% by mass of an organic solvent based on the total mass of water and the organic solvent to obtain carboxymethyl cellulose, wherein the amount of lithium ions contained in 1 g of the lithium carboxymethyl cellulose salt is 30,000 to 50,000 ppm. (2) The method for producing a carboxymethyl cellulose lithium salt according to (1), wherein the carboxymethyl cellulose lithium salt has a viscosity of 1,000 to 20,000 mPa s at 25°C as measured using a Brookfield viscometer when made into a 1% by mass aqueous solution. (3) A method for producing an electrode composition for a non-aqueous electrolyte secondary battery, comprising the step of mixing the carboxymethyl cellulose lithium salt produced by the production method according to (1), an electrode active material, and an aqueous solvent. (4) A method for producing an electrode for a non-aqueous electrolyte secondary battery, comprising the step of applying the electrode composition for a non-aqueous electrolyte secondary battery produced by the production method according to (3) to a current collector. (5) A method for producing a non-aqueous electrolyte secondary battery, comprising the step of laminating the electrode for a non-aqueous electrolyte secondary battery produced by the production method according to (4), a separator, and a positive electrode. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a method for producing, at low cost, carboxymethyl cellulose lithium salt, which, when used in a nonaqueous electrolyte secondary battery, can provide a battery with a large battery capacity and an excellent capacity retention rate. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below. In the present invention, "to" includes the extreme values. That is, "X to Y" includes the values ​​X and Y at both ends.

[0016] <Method of manufacturing carboxymethyl cellulose lithium salt> The method of the present invention for producing a lithium carboxymethyl cellulose salt (hereinafter sometimes abbreviated as "CMC-Li") having a degree of carboxymethyl substitution per anhydroglucose unit of 0.5 to 2.0 comprises: step (A): treating cellulose with lithium hydroxide in a solvent containing 20 mass% or more of water to obtain mercerized cellulose; and step (B): reacting the mercerized cellulose with a carboxymethylating agent in a mixed solvent containing 50 to 99 mass% of an organic solvent based on the total mass of water and the organic solvent to obtain carboxymethyl cellulose, wherein the amount of lithium ions contained in 1 g of the lithium carboxymethyl cellulose salt is 30,000 to 50,000 ppm.

[0017] (Process (A)) The production method of the present invention includes step (A): treating cellulose with lithium hydroxide in a solvent containing 20% ​​by mass or more of water to obtain mercerized cellulose.

[0018] (cellulose) In the present invention, cellulose refers to a polysaccharide having a structure in which D-glucopyranose (also simply referred to as "glucose residue" or "anhydroglucose") units are linked together via β-1,4 bonds. Cellulose is generally classified into native cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose (which is cellulose obtained by removing the amorphous region), etc., based on its origin and production method. In the present invention, any of these celluloses can be used as a raw material for mercerized cellulose.

[0019] Examples of natural cellulose include bleached pulp or unbleached pulp (bleached wood pulp or unbleached wood pulp); linters, purified linters; and cellulose produced by microorganisms such as acetic acid bacteria. The raw materials for bleached pulp or unbleached pulp are not particularly limited, and examples include wood, cotton, straw, bamboo, hemp, jute, and kenaf. The method for producing bleached pulp or unbleached pulp is also not particularly limited, and may be a mechanical method, a chemical method, or a method that is an intermediate combination of the two. Examples of bleached or unbleached pulp classified by production method include mechanical pulp (thermomechanical pulp (TMP), groundwood pulp), chemical pulp (sulfite pulp such as softwood unbleached sulfite pulp (NUSP) and softwood bleached sulfite pulp (NBSP), and kraft pulp such as softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and hardwood bleached kraft pulp (LBKP)). In addition to papermaking pulp, dissolving pulp may also be used. Dissolving pulp is chemically refined pulp that is primarily dissolved in chemicals before use and is the main raw material for artificial fibers, cellophane, etc.

[0020] Examples of regenerated cellulose include cellulose dissolved in a certain solvent such as a cuprammonium solution, a cellulose xanthate solution, or a morpholine derivative, and then spun again. Examples of fine cellulose include those obtained by depolymerizing cellulosic materials, including the above-mentioned natural cellulose and regenerated cellulose (e.g., acid hydrolysis, alkaline hydrolysis, enzymatic decomposition, crushing treatment, vibrating ball mill treatment, etc.), and those obtained by mechanically treating the above-mentioned cellulosic materials.

[0021] (mercerization) Mercerized cellulose (also called alkali cellulose) is obtained by adding a mercerizing agent (alkali) to the above-mentioned cellulose as a raw material. In the present invention, a solvent containing 20% ​​by mass or more of water is used as the solvent in the mercerization reaction, and a mixed solvent of an organic solvent and water is used in the subsequent carboxymethylation, thereby making it possible to economically obtain CMC-Li having the desired degree of carboxymethyl substitution.

[0022] A solvent containing 20% ​​or more by mass of water refers to a solvent in which the mass of water is 20 parts or more when the mass of the entire solvent is 100 parts. The remainder of the solvent other than water may be an organic solvent. As described above, the solvent used in the mercerization reaction is a solvent containing 20% ​​or more by mass of water, preferably 30% or more by mass, and more preferably 50% or more by mass. By containing 20% ​​or more by mass of water during mercerization, lithium hydroxide (mercerizing agent) is completely dissolved in the solvent, enabling a uniform mercerization reaction. There is no upper limit to the water proportion, and it may be 100% by mass (i.e., the solvent is water). However, from the viewpoint of improving the effective utilization rate of the carboxymethylating agent described below, it is also preferable that the water proportion be 50% or less by mass.

[0023] Examples of solvents other than water (used in a mixture with water) in a solvent containing 20% ​​or more by mass of water include organic solvents used as solvents in the subsequent carboxyalkylation step. Examples include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary butanol; ketones such as acetone, diethyl ketone, and methyl ethyl ketone; and dioxane, diethyl ether, benzene, and dichloromethane. These solvents, alone or in combination, can be added to water in an amount of 80% by mass or less and used as the solvent for mercerization. The organic solvent content in the solvent used in the mercerization reaction is preferably 70% by mass or less, and more preferably 50% by mass or less. There is no lower limit to the proportion of the organic solvent, and it may even be 0% by mass.

[0024] In the present invention, it is necessary to use lithium hydroxide as the mercerizing agent. The mercerizing agent is not limited thereto, but can be added to the reactor as an aqueous solution of, for example, 1 to 60 mass %, preferably 2 to 45 mass %, more preferably 3 to 25 mass %.

[0025] The amount of mercerizing agent used is not particularly limited as long as it allows carboxymethyl cellulose to achieve the desired degree of carboxymethyl substitution, but it is preferable to use an amount that allows the production of carboxymethyl cellulose having a degree of carboxymethyl substitution of 0.50 to 2.0. In one embodiment, the amount of mercerizing agent used is preferably 0.1 mol or more and 10.0 mol or less, more preferably 1.5 mol or more and 9.0 mol or less, and even more preferably 3.0 mol or more and 8.2 mol or less, relative to 100 g (bone dry) of cellulose.

[0026] The amount of the solvent, mainly composed of water, used during mercerization is not particularly limited as long as it allows the raw materials to be stirred and mixed, but it is preferably 1.5 to 20 times by mass, more preferably 2 to 10 times by mass, relative to the cellulose raw materials.

[0027] The mercerization treatment is preferably carried out by mixing the raw material (cellulose) with a solvent containing 20% ​​or more by mass of water and adjusting the temperature of the reactor to less than 50°C. By keeping the temperature below 50°C, the reaction is more likely to proceed uniformly, resulting in the production of carboxymethyl cellulose with the desired viscosity. Furthermore, side reactions can be suppressed, thereby improving the effective utilization rate of the carboxymethylating agent described below. The temperature of the reactor is preferably from 0°C to less than 50°C, more preferably from 10°C to less than 50°C, and more preferably from 10°C to 40°C.

[0028] Mercerization is carried out by adding an aqueous solution of a mercerizing agent (lithium hydroxide) to a reactor containing the raw material (cellulose) and solvent, and adjusting the temperature as described above, and stirring for 15 minutes to 8 hours, preferably 30 minutes to 7 hours, and more preferably 30 minutes to 3 hours, thereby obtaining mercerized cellulose (alkali cellulose).

[0029] The pH during mercerization is preferably 9 or higher, which allows the mercerization reaction to proceed. The pH is more preferably 11 or higher, even more preferably 12 or higher, and may be 13 or higher. There is no particular upper limit to the pH.

[0030] Mercerization can be carried out using a reactor capable of mixing and stirring the above components while controlling the temperature, and various reactors conventionally used for mercerization reactions can be used. For example, a batch-type stirring device having two shafts for stirring and mixing the above components is preferred from the viewpoints of both uniform mixing and productivity.

[0031] (Process (B)) The production method of the present invention includes step (B): a step of reacting mercerized cellulose with a carboxymethylating agent in a mixed solvent containing 50 to 99% by mass of an organic solvent based on the total mass of water and the organic solvent to obtain carboxymethyl cellulose.

[0032] (Carboxymethylation) Carboxymethyl cellulose is obtained by adding a carboxymethylating agent (also called an etherifying agent) to mercerized cellulose. In the present invention, a mixed solvent of water and an organic solvent is used as the solvent in this carboxymethylation reaction. By using a solvent containing 20 mass% or more of water during mercerization and a mixed solvent of water and an organic solvent during carboxymethylation, it is possible to obtain carboxymethyl cellulose in which the carboxymethyl groups are uniformly substituted.

[0033] Examples of the carboxymethylating agent include monochloroacetic acid, sodium monochloroacetate, methyl monochloroacetate, ethyl monochloroacetate, and isopropyl monochloroacetate. Of these, monochloroacetic acid is more preferred from the viewpoints of easy availability of the raw material and the fact that it does not contain sodium ions.

[0034] The amount of the carboxymethylating agent used is not particularly limited as long as it achieves the desired degree of carboxymethyl substitution in carboxymethyl cellulose. However, it is preferable to use an amount that enables the production of carboxymethyl cellulose with a degree of carboxymethyl substitution of 0.5 to 2.0. When the degree of carboxymethyl substitution is 0.5 to 2.0, the cellulose becomes soluble in water. In one embodiment, the amount of the carboxymethylating agent used is preferably in the range of 0.1 to 10.0 mol per anhydroglucose unit of cellulose. The lower limit of this range is more preferably 1.0 mol or more, even more preferably 3.0 mol or more, and the upper limit is more preferably 9.0 mol or less, even more preferably 7.0 mol or less. The carboxymethylating agent can be added to the reactor as, for example, a 5 to 80 mass % aqueous solution, more preferably 30 to 60 mass %, or in the form of a powder without being dissolved.

[0035] When monochloroacetic acid is used as the carboxymethylating agent, the molar ratio of the mercerizing agent (lithium hydroxide) to the carboxymethylating agent (mercerizing agent / carboxymethylating agent) is generally set to 0.9 to 2.45. This is because if the ratio is less than 0.9, the carboxymethylation reaction may be insufficient, resulting in unreacted monochloroacetic acid remaining and wasting, and if the ratio exceeds 2.45, a side reaction between the excess mercerizing agent and monochloroacetic acid may proceed, resulting in the production of an alkali metal glycolate, which may be uneconomical.

[0036] Examples of organic solvents include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary butanol; ketones such as acetone, diethyl ketone, and methyl ethyl ketone; and dioxane, diethyl ether, benzene, and dichloromethane. These can be used alone or in combination with water to form a solvent for carboxymethylation. Among these, monohydric alcohols having 1 to 4 carbon atoms are preferred, and monohydric alcohols having 1 to 3 carbon atoms are more preferred, due to their excellent compatibility with water.

[0037] The proportion of organic solvent in the mixed solvent during carboxymethylation is 50% by mass or more, preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, of the total of water and organic solvent. The higher the proportion of organic solvent, the more uniformly carboxymethyl groups are substituted in the resulting carboxymethyl cellulose. The upper limit of the proportion of organic solvent is 99% by mass or less. Considering the cost of the organic solvent to be added, the proportion is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and even more preferably 83% by mass or less.

[0038] A mixed solvent of water and an organic solvent is prepared, and the carboxymethylating agent is added to the mercerized cellulose. The mixture is stirred for 15 minutes to 4 hours, preferably 15 minutes to 1 hour, while maintaining a constant temperature, preferably in the range of 10 to 40°C. Mixing of the mercerized cellulose-containing liquid with the carboxymethylating agent is preferably carried out in multiple batches or by dropwise addition to prevent the reaction mixture from becoming too hot. After adding the carboxymethylating agent and stirring for a certain period of time, the temperature is raised, if necessary, to 30 to 90°C, preferably 40 to 90°C, more preferably 60 to 80°C, and the etherification (carboxymethylation) reaction is carried out for 30 minutes to 10 hours, preferably 1 to 4 hours, to obtain a lithium salt of carboxymethyl cellulose (hereinafter sometimes abbreviated as CMC-Li).

[0039] In the carboxymethylation, the reactor used in the mercerization may be used as it is, or a separate reactor may be used which is capable of mixing and stirring the above components while controlling the temperature.

[0040] After the reaction is complete, the remaining alkali metal salt may be neutralized with a mineral acid or an organic acid. If necessary, by-products such as inorganic salts and organic acid salts may be removed by washing with aqueous methanol, followed by drying, pulverization, and classification to obtain CMC-Li. Examples of equipment used in dry pulverization include impact mills such as hammer mills and pin mills, media mills such as ball mills and tower mills, and jet mills. Examples of equipment used in wet pulverization include homogenizers, mass colloiders, and pearl mills.

[0041] (Carboxymethylcellulose lithium salt) Carboxymethyl cellulose lithium salt (CMC-Li) can be obtained through steps (A) and (B). Carboxymethyl cellulose is cellulose in which carboxymethyl groups are ether-bonded to some of the hydroxyl groups of glucose residues.

[0042] The CMC-Li obtained by the production method of the present invention has a degree of carboxymethyl substitution (hereinafter sometimes referred to as "DS value") per anhydrous glucose unit of cellulose of 0.5 to 2.0. The DS value is 0.5 or more from the viewpoint of improving the dispersibility of electrode active materials and the like when used in an electrode composition. Furthermore, the DS value is 2.0 or less from the viewpoint of improving the adhesive strength to an electrode plate. Therefore, the DS value of the CMC-Li obtained by the present invention is 0.5 to 2.0, preferably 0.7 to 1.8, and more preferably 1.0 to 1.7. The degree of carboxymethyl substitution can be adjusted by controlling the amount of carboxymethylating agent added to be reacted, the amount of mercerizing agent, the composition ratio of water to organic solvent, etc.

[0043] In the present invention, the term "anhydroglucose unit" refers to each anhydroglucose (glucose residue) constituting cellulose. The term "carboxymethyl substitution degree (also referred to as "etherification degree") refers to the proportion of hydroxyl groups in the glucose residues constituting cellulose that have been substituted with carboxymethyl ether groups (the number of carboxymethyl ether groups per glucose residue).

[0044] The degree of carboxymethyl substitution is measured as follows: Weigh out approximately 2.0 g of sample and place it in a 300 mL Erlenmeyer flask with a stopper. Add 100 mL of a solution of 1000 mL of nitric acid methanol and 100 mL of special-grade concentrated nitric acid, and shake for 3 hours to convert carboxymethyl cellulose salt (CMC) to H-CMC (hydrogen-form carboxymethyl cellulose). Weigh out 1.5 to 2.0 g of the bone-dry H-CMC and place it in a 300 mL Erlenmeyer flask with a stopper. Wet the H-CMC with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake for 3 hours at room temperature. Using phenolphthalein as an indicator, back-titrate the excess NaOH with 0.1 N H2SO4, and calculate the degree of carboxymethyl substitution (CM-DS) using the following formula: A = [(100 × F - 0.1N-H2SO4 (mL) × F') × 0.1] / (bone-dry mass of H-CMC (g)) Carboxymethyl substitution degree (CM-DS) = 0.162 × A / (1-0.058 × A) A: Amount of 1N NaOH (mL) required to neutralize 1g of H-CMC F': Factor of 0.1N-H2SO4 F: Factor of 0.1N NaOH.

[0045] The carboxymethylcellulose lithium salt produced by the present invention can be used in the form of a dispersion obtained after the reaction, or it can be dried and redispersed in water as needed. The drying method is not particularly limited, and known methods such as freeze drying, spray drying, tray drying, drum drying, belt drying, thinly spreading on a glass plate or the like and drying, fluidized bed drying, microwave drying, and heated fan-type reduced pressure drying can be used. After drying, the salt can be pulverized using a cutter mill, hammer mill, pin mill, jet mill, or the like, if necessary. The method for redispersing the salt in water is also not particularly limited, and known dispersing devices can be used.

[0046] (Lithium ion content) The lithium carboxymethyl cellulose salt produced by the present invention contains 30,000 to 50,000 ppm of lithium ions per gram, preferably 33,000 to 50,000 ppm, and more preferably 35,000 to 48,000 ppm, from the viewpoint of maintaining discharge capacity when used in a nonaqueous electrolyte secondary battery. If the lithium ion content is less than the lower limit, the DS value will be less than 0.5, which may result in insolubility in water and a large amount of undissolved matter. If the lithium ion content is greater than the upper limit, the DS value will exceed 2.0, which may result in low viscosity and poor coatability. The lithium ion content can be adjusted by adjusting the amount of mercerizing agent used.

[0047] The carboxymethyl cellulose lithium salt produced by the present invention preferably has a sodium ion content per gram of 3,000 ppm or less, more preferably 2,000 ppm or less, and even more preferably 1,000 ppm or less, from the viewpoint of maintaining discharge capacity when used in a non-aqueous electrolyte secondary battery, and it is particularly preferable that the salt contains substantially no sodium ions.

[0048] (Viscosity of CMC-Li) The viscosity of a 1% by mass aqueous solution of the CMC-Li obtained in this manner, measured at 25°C with a Brookfield viscometer (30 rpm), is preferably 1,000 to 20,000 mPa·s, more preferably 3,000 to 15,000 mPa·s, and even more preferably 3,000 to 8,000 mPa·s. If this viscosity is too high, there is a problem of poor coatability. If this viscosity is too low, there is a problem of low adhesive strength to the electrode plate.

[0049] The viscosity was measured as follows: CMC-Li was weighed into a 1,000 mL glass beaker and dispersed in 900 mL of distilled water to prepare an aqueous dispersion with a solids content of 1% (w / v). The aqueous dispersion was stirred at 600 rpm for 3 hours at 25°C using a stirrer. The viscosity was then measured after 3 minutes at 30 rpm using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) according to the method of JIS-Z-8803.

[0050] The present invention provides a method for producing CMC-Li with specific properties at low cost. Furthermore, when the CMC-Li obtained by the present invention is used in a non-aqueous electrolyte secondary battery, the battery capacity and capacity retention rate can be improved.

[0051] (Binder for non-aqueous electrolyte secondary batteries) The CMC-Li obtained by the production method of the present invention can be used as an electrode binder for non-aqueous electrolyte secondary batteries. Typically, an aqueous solution containing CMC-Li is used as an electrode binder for non-aqueous electrolyte secondary batteries. The concentration of CMC-Li in the aqueous CMC-Li solution is typically 0.1 to 10 mass%, preferably 0.2 to 4 mass%, and more preferably 0.5 to 2 mass%.

[0052] There are no particular limitations on the conditions for producing an aqueous solution of CMC-Li. For example, the solution is prepared by adding CMC-Li to water (e.g., distilled water, purified water, tap water, etc.) and dissolving it by stirring, etc., as necessary.

[0053] Furthermore, binders for non-aqueous electrolyte secondary batteries may include other binders in addition to CMC-Li. Examples of binders used in electrode compositions for negative electrodes include carboxymethyl cellulose, carboxymethyl cellulose salts (excluding lithium salts), and synthetic rubber binders. Examples of synthetic rubber binders that can be used include one or more 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. Among these, styrene butadiene rubber (SBR) is preferred. Examples of binders used in electrode compositions for positive electrodes include the synthetic rubber binders listed above as binders for negative electrodes, as well as polytetrafluoroethylene (PTFE).

[0054] <Method of manufacturing electrode composition for non-aqueous electrolyte secondary battery> In the method for producing an electrode composition for a non-aqueous electrolyte secondary battery (hereinafter, sometimes referred to as "electrode composition") of the present invention, the CMC-Li obtained as described above is used as a binder for a non-aqueous electrolyte secondary battery, and the method includes a step of mixing this CMC-Li with an electrode active material and an aqueous solvent.

[0055] That is, the CMC-Li obtained by the production method of the present invention can be used as an electrode binder to constitute an electrode composition together with an electrode active material and an aqueous solvent. In this case, the content of the carboxymethyl cellulose lithium salt in the electrode composition is preferably 0.1 to 4.0 mass% based on the total mass of the electrode composition.

[0056] When the other binders are used, the content of the binder for a non-aqueous electrolyte secondary battery in the electrode composition is preferably 1 to 10 mass %, more preferably 1 to 6 mass %, and even more preferably 1 to 2 mass %.

[0057] (electrode active material) The electrode active material contained in the electrode composition for a non-aqueous electrolyte secondary battery is a negative electrode active material when the electrode for a non-aqueous electrolyte secondary battery is a negative electrode, and is a positive electrode active material when the electrode is a positive electrode.

[0058] 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 with carbon and / or the said 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 as the graphite and silicon-based compounds are more preferable.

[0059] Note that the silicon oxide in the present invention means SiO x (represented by 0 < x ≦ 2). Also in the present invention, as the electrode layer, a composite of a silicon-based compound and a graphite material can also be used.

[0060] 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.

[0061] [[ID=ID=17]]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.

[0062] 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, still more preferably 95 to 99% by mass, particularly preferably 96 to 99% by weight, and most preferably 98 to 99% by mass.

[0063] The electrode composition may also contain a conductive aid as needed. Examples of conductive aids include conductive carbons such as carbon black, acetylene black, and ketjen black. The content of the conductive aid in the electrode composition is usually 0.01 to 20% by mass, and preferably 0.1 to 10% by mass.

[0064] (aqueous solvent) The solvent used in the method for producing an electrode composition is an aqueous solvent. The type of aqueous solvent is not particularly limited, but is preferably water, a water-soluble organic solvent, or a mixed solvent thereof, and more preferably water.

[0065] The water-soluble organic solvent is an organic solvent that dissolves in water. Examples of water-soluble organic solvents 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 succinate triglycol diester, acetic acid, and combinations thereof.

[0066] When the mixed solvent is used as the aqueous solvent, the amount of the 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, more preferably 90% by mass or less. Furthermore, the aqueous solvent may contain a water-insoluble organic solvent as long as it does not impair the effects of the invention.

[0067] The conditions for producing the electrode composition are not particularly limited. For example, other components constituting the electrode composition are added to an aqueous solution of carboxymethyl cellulose lithium salt, and the mixture is mixed while stirring as necessary. The form of the electrode composition is not particularly limited, and may be, for example, a liquid, a paste, a slurry, or any other form.

[0068] <Method of manufacturing an electrode for a non-aqueous electrolyte secondary battery> An electrode layer can be formed on a current collector by applying the electrode composition to the current collector. Examples of application methods include blade coating, bar coating, and die coating, with blade coating being preferred. For example, blade coating can be achieved by casting the electrode composition onto the current collector using a coating device such as a doctor blade. The lamination method is not limited to the specific example described above, and can also be achieved by discharging the electrode composition from an extrusion-type injector having a slot nozzle onto a running current collector wound around a backup roll. In blade coating, after casting, the electrode layer can be obtained by further drying, such as by heating (for example, at a temperature of 80 to 120°C, for example, for a heating time of 4 to 12 hours), or by applying pressure using a roll press, as needed.

[0069] The shape of the electrode for a non-aqueous electrolyte secondary battery obtained by the production method of the present invention is not particularly limited, but is usually a sheet. The thickness of the sheet-shaped electrode plate (the thickness of the electrode layer formed from the electrode composition, excluding the current collector portion) is difficult to specify because it depends on the composition of the composition and production conditions, but is usually 30 to 150 μm.

[0070] (current collector) Any electrical conductor that does not cause a fatal chemical reaction in the constructed electrode or battery can be used as the current collector. If the electrode is a negative electrode, a negative electrode current collector can be used, and if the electrode is a positive electrode, a positive electrode current collector can be used.

[0071] Examples of materials for the negative electrode current collector include stainless steel, nickel, copper, titanium, carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium or silver, etc. Among these, copper or a copper alloy is 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. The current collector may be in the form of a mesh, punched metal, foam metal, or foil processed into a plate shape, with foil processed into a plate shape being preferred.

[0072] <Method of manufacturing non-aqueous electrolyte secondary battery> The present invention also provides a method for producing 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 separators interposed therebetween and wound multiple times. For example, a non-aqueous electrolyte secondary battery can be obtained by using the electrode for a non-aqueous electrolyte secondary battery obtained by the production method of the present invention as a negative electrode, stacking this negative electrode, a separator, and a positive electrode, and winding the stack multiple times to obtain a laminate, placing the laminate in a battery container, injecting a non-aqueous electrolyte, and sealing the container.

[0073] The shape of the nonaqueous electrolyte secondary battery is not particularly limited, and may be a cylindrical shape, a prismatic shape, a flat shape, a coin shape, a button shape, a sheet shape, etc. The material of the battery container is not particularly limited as long as it can prevent moisture from entering the battery, and examples thereof include a laminate of metal, aluminum, etc.

[0074] The separator is usually impregnated with a non-aqueous electrolyte. The separator may be, for example, a microporous membrane or nonwoven fabric made of polyolefin such as polyethylene or polypropylene.

[0075] The non-aqueous electrolyte typically contains 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. One type of non-aqueous solvent may be used alone, or two or more types may be used in combination. The concentration of the lithium salt in the non-aqueous electrolyte is typically 0.5 to 2.5 mol / L.

[0076] According to the method for producing CMC-Li of the present invention, it is possible to produce, at low cost, carboxymethyl cellulose lithium salt, which, when used as an electrode binder for non-aqueous electrolyte secondary batteries, can provide non-aqueous electrolyte secondary batteries with large battery capacity and excellent capacity retention. [Example]

[0077] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0078] <Measurement and evaluation methods> The carboxymethyl cellulose salts (lithium carboxymethyl cellulose salts or sodium carboxymethyl cellulose salts) obtained in the examples and comparative examples and the non-aqueous electrolyte secondary batteries were measured and evaluated for various indices by the following methods.

[0079] <Lithium ion content> The lithium ion content was measured by placing 1 g of carboxymethyl cellulose salt in a crucible, heating it in an electric furnace at 500°C for 1 to 3 hours, and then cooling it to room temperature. After that, 1 mL of 6N hydrochloric acid was added, and the mixture was evaporated on a hot plate at 100°C until the solvent was completely removed. After cooling to room temperature, 1 mL of 6N hydrochloric acid was added again, and the crucible was heated on a hot plate at 50°C for approximately 10 minutes. After cooling to room temperature, ultrapure water was added, and the mixture was transferred to a 50 mL measuring flask, and further ultrapure water was added to bring the volume to 50 mL. The solution thus prepared was measured by ion chromatography.

[0080] <Carboxymethyl Substitution Degree (CM-DS)> Approximately 2.0 g of ground carboxymethylcellulose salt sample was weighed and placed in a 300 mL Erlenmeyer flask with a stopper. 100 mL of a solution of 1,000 mL of methanol and 100 mL of concentrated nitric acid was added and the mixture was shaken for 3 hours to convert carboxymethylcellulose salt (CMC salt) to H-CMC (carboxymethylcellulose). 1.5-2.0 g of bone-dried H-CMC was weighed and placed in a 300 mL Erlenmeyer flask with a stopper. The H-CMC was moistened with 15 mL of 80% methanol, 100 mL of 0.1 N NaOH was added, and the mixture was shaken at room temperature for 3 hours. Excess NaOH was back-titrated with 0.1 N H2SO4 using phenolphthalein as an indicator. CM-DS was calculated using the following equation. (Formula 1) A = [(100 × F - (0.1N H2SO4 (mL)) × F') × 0.1] / (bone-dry mass of H-CMC (g)) Carboxymethyl substitution degree (CM-DS) = 0.162 × A / (1-0.058 × A) A: Amount of 1N NaOH (mL) required to neutralize 1g of H-CMC F': Factor of 0.1N H2SO4 F: Factor of 0.1N NaOH

[0081] <Viscosity> Carboxymethylcellulose salt was weighed into a 1,000 mL glass beaker and dispersed in 900 mL of distilled water to prepare an aqueous dispersion with a solids content of 1% (w / v). The aqueous dispersion was stirred at 600 rpm for 3 hours at 25°C using a stirrer. The viscosity was then measured after 3 minutes at 30 rpm using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) according to the method of JIS-Z-8803.

[0082] <Battery evaluation> (Discharge capacity (charge / discharge rate test)) The charge-discharge rate test of the coin-type nonaqueous electrolyte secondary batteries obtained in the Examples and Comparative Examples was carried out using Nagano Corporation's BTS2004 in a thermostatic chamber at 25° C., with 52 cycles being performed, with one cycle consisting of a charge treatment followed by a discharge treatment. Note that the charge treatment conditions were a constant current-constant voltage (CC-CV) method (CC current 0.2 C, CV voltage 4.2 V, final current 0.02 C) for all cycles. As a condition for the discharge treatment, the final voltage was set to 3.0 V. In the first cycle, the discharge treatment was performed at a constant current of 0.2 C, and the discharge capacity (mAh / g) after one cycle was measured. After that, up to the 52nd cycle, the constant current for the discharge treatment was set as follows, and the discharge capacity (mAh / g) was measured after each cycle. (Constant current for discharge treatment in each cycle) 2 to 10 cycles: Discharge treatment at a constant current of 0.2C 11 to 20 cycles: constant current 1C for discharge treatment 21 cycles cycles: Constant current of 0.2C for discharge treatment 22 - 31 cycles: Constant current of 2C for discharge treatment 32 cycles: Constant current of 0.2C for discharge treatment 33 - 42 cycles: Constant current of 3C for discharge treatment 43 - 52 cycles: Constant current of 0.2C for discharge treatment

[0083] (Capacity retention rate) The capacity retention rate was calculated from the discharge capacity (mAh / g) in each of the above cycle tests using the formula "Capacity retention rate = Discharge capacity (mAh / g) after 52 cycles / Discharge capacity (mAh / g) after 1 cycle × 100".

[0084] (Example 1) <Preparation of CMC - Li> To a 5L twin - shaft kneader with the rotation speed adjusted to 100 rpm, a solution of 119 parts of lithium hydroxide dissolved in 326 parts of water was added, and 100 parts were charged based on the dry mass when the lint pulp was dried at 100 °C for 60 minutes. It was stirred and mixed at 30 °C for 60 minutes to prepare mercerized cellulose. While further stirring, 229 parts of monochloroacetic acid were added, and then it was stirred for 30 minutes. 1407 parts of isopropanol (IPA) were added, and after stirring at 30 °C for 30 minutes, the temperature was raised to 70 °C over 30 minutes, and a carboxymethylation reaction was carried out at 70 °C for 60 minutes. After the reaction, it was neutralized, washed, de - liquidized, dried, and pulverized to obtain a lithium salt of carboxymethylated cellulose with a carboxymethyl substitution degree of 1.39 and a viscosity of 5,450 mPa·s for a 1 mass% aqueous solution measured with a B - type viscometer at 25 °C (hereinafter sometimes referred to as "CMC - Li1"). The measurement of the carboxymethyl substitution degree and the viscosity of the 1 mass% aqueous solution was carried out as described above.

[0085] <Preparation of negative electrode plate> SiOx as anode material, acetylene black (manufactured by Stream Chemical Co.) as a conductive additive, CMC-Li1 as a binder, and styrene butadiene rubber (SBR, manufactured by ENEOS Materials Corporation, part number TRD 104A) were mixed to a solids weight ratio of 97:0.5:1.0:1.5, and water was added to a slurry concentration of 45.6 mass%. The mixture was thoroughly stirred using a Mazerustar (manufactured by Kurabo Industries, KK-250S) to obtain Slurry 1. This slurry was applied to a copper foil (manufactured by Furukawa Electric Co., Ltd., NC-WS) measuring 320 mm in length, 170 mm in width, and 17 μm in thickness using an applicator. The foil was then air-dried for 30 minutes and then dried in a dryer at 60 °C for 30 minutes. The foil was then pressed using a small tabletop roll press (manufactured by Tester Sangyo Co., Ltd., SA-602) at 5 kN and a roll peripheral speed of 50 m / min, resulting in a coating weight of 19.7 g / m. 2 A negative electrode plate with an effective discharge capacity of 2100 mAh / g was obtained.

[0086] <Fabrication of coin-type non-aqueous electrolyte secondary battery> The obtained negative electrode plate and a LiCoO2 positive electrode plate (manufactured by Hosensha, basis weight 110.2 g / m) were 2 The negative electrode plate and the positive electrode plate (effective discharge capacity 145 mAh / g) were punched out into a circle having a diameter of 16 mm, and the punched negative electrode plate and the positive electrode plate were dried in a vacuum at 120° C. for 12 hours.

[0087] Similarly, a separator (manufactured by CS Tech, polypropylene separator having a thickness of 20 μm) was punched out into a circle having a diameter of 17 mm, and vacuum dried at 60° C. for 12 hours.

[0088] The negative electrode plate was then placed in a stainless steel circular dish-shaped container with a diameter of 20.0 mm, followed by stacking a separator, a positive electrode plate, a spacer (diameter 15.5 mm, thickness 1 mm), and a stainless steel washer (manufactured by Hosen Co., Ltd.) in that order. 300 μL of electrolyte (1 mol / L LiPF6, ethylene carbonate and diethyl carbonate in a volume ratio of 1:1) was then added to the circular dish-shaped container. A stainless steel cap was placed over the container via a polypropylene packing, and the container was sealed using a coin battery crimping machine (manufactured by Hosen Co., Ltd.) to obtain a coin-shaped nonaqueous electrolyte secondary battery.

[0089] Example 2 A 5-L twin-screw kneader was adjusted to 100 rpm and charged with 119 parts of lithium hydroxide dissolved in 434 parts of water. This mixture was then mixed with 100 parts of linter pulp (based on the dry mass of the pulp dried at 100°C for 60 minutes). This mixture was stirred at 30°C for 60 minutes to prepare mercerized cellulose. While stirring, 229 parts of monochloroacetic acid was added, followed by stirring for 30 minutes. 1407 parts of isopropanol (IPA) was added, and the mixture was stirred at 30°C for 30 minutes. The mixture was then heated to 70°C over 30 minutes and carboxymethylated for 60 minutes at 70°C. After the reaction was complete, the mixture was neutralized, washed, drained, dried, and pulverized to obtain a lithium salt of carboxymethylated cellulose (CMC-Li2). The carboxymethyl substitution degree was 1.25, and the viscosity of a 1% by weight aqueous solution measured at 25°C with a Brookfield viscometer was 5,560 mPa·s. A coin-type non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the obtained CMC-Li2 was used.

[0090] Example 3 A 5-L twin-screw kneader adjusted to 100 rpm was charged with 193 parts of lithium hydroxide dissolved in 528 parts of water. This mixture was then mixed with 100 parts of linter pulp (based on the dry mass of the pulp dried at 100°C for 60 minutes) at 30°C for 60 minutes, producing mercerized cellulose. While stirring, 371 parts of monochloroacetic acid was added, followed by 30 minutes of stirring. 2280 parts of isopropanol (IPA) was added, and the mixture was stirred at 30°C for 30 minutes. The mixture was then heated to 70°C over 30 minutes and carboxymethylated for 60 minutes at 70°C. After the reaction was complete, the mixture was neutralized, washed, drained, dried, and pulverized to obtain a lithium salt of carboxymethylated cellulose (CMC-Li3). The carboxymethyl substitution degree was 1.60, and the viscosity of a 1% by weight aqueous solution measured at 25°C with a Brookfield viscometer was 3,550 mPa·s. A coin-type non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the obtained CMC-Li3 was used.

[0091] (Comparative Example 1) A 5-L twin-screw kneader with the rotation speed adjusted to 100 rpm was charged with 118 parts of lithium hydroxide dissolved in 326 parts of water and 1407 parts of isopropanol (IPA). This mixture was then mixed and stirred for 60 minutes at 30°C to prepare mercerized cellulose. 229 parts of monochloroacetic acid was added with further stirring, and the mixture was stirred for 60 minutes. After stirring, the mixture was heated to 70°C over 30 minutes and allowed to carboxymethylate for 60 minutes at 70°C. After the reaction was completed, the mixture was neutralized, washed, drained, dried, and pulverized to obtain a lithium salt of carboxymethylated cellulose (CMC-Li4). The carboxymethyl substitution degree was 0.91 and the viscosity of a 1% by weight aqueous solution measured with a Brookfield viscometer at 25°C was 116 mPa·s. A coin-type nonaqueous electrolyte secondary battery was prepared in the same manner as in Example 1, except that the obtained CMC-Li4 was used.

[0092] (Comparative Example 2) A 5-L twin-screw kneader with the rotation speed adjusted to 100 rpm was charged with 199 parts of sodium hydroxide dissolved in 326 parts of water. 100 parts of linter pulp (based on the dry mass of the pulp dried at 100°C for 60 minutes) was added. Stirring and mixing were continued for 60 minutes at 30°C to prepare mercerized cellulose. 229 parts of monochloroacetic acid was added with further stirring, followed by stirring for 30 minutes. 1407 parts of isopropanol (IPA) was added, and the mixture was stirred at 30°C for 30 minutes. The mixture was then heated to 70°C over 30 minutes and subjected to a carboxymethylation reaction at 70°C for 60 minutes. After the reaction was completed, the mixture was neutralized, washed, drained, dried, and pulverized to obtain a sodium salt of carboxymethyl cellulose (CMC-Na) with a carboxymethyl substitution degree of 1.07 and a viscosity of a 1% by weight aqueous solution of 2,420 mPa·s measured with a Brookfield viscometer at 25°C. A coin-type nonaqueous electrolyte secondary battery was prepared in the same manner as in Example 1, except that the obtained CMC-Na was used.

[0093] Table 1 shows the measurement and evaluation results of the carboxymethylcellulose lithium salt or carboxymethylcellulose sodium salt and the nonaqueous electrolyte secondary batteries obtained in the examples and comparative examples.

[0094] [Table 1]

[0095] As shown in Table 1, the batteries obtained using the lithium carboxymethyl cellulose salts of Examples 1 to 3, which were produced by a method for producing a lithium carboxymethyl cellulose salt having a degree of carboxymethyl substitution of 0.5 to 2.0, including: step (A): treating cellulose with lithium hydroxide in a solvent containing 20 mass% or more of water to obtain mercerized cellulose; and step (B): reacting the mercerized cellulose with a carboxymethylating agent in a mixed solvent containing an organic solvent in an amount of 50 to 99 mass% based on the total mass of water and the organic solvent to obtain carboxymethyl cellulose, and in which the amount of lithium ions contained per gram of the lithium carboxymethyl cellulose salt was 30,000 to 50,000 ppm, were excellent in battery capacity and capacity retention rate.

[0096] In Comparative Example 1, which did not contain 20% by mass or more of water as a solvent during mercerization in step (A), the 1% viscosity of the resulting CMC-Li was lower than that of Examples 1 to 3, and the batteries obtained using this CMC-Li were inferior to the batteries of Examples 1 to 3 in both battery capacity and capacity retention rate.

[0097] In addition, in Comparative Example 2, in which 100% by mass of water was used as the solvent for mercerization in step (A) but sodium hydroxide was used instead of lithium hydroxide to perform mercerization, the resulting CMC-Na did not contain lithium ions, and the battery obtained using this CMC-Na had an inferior capacity retention rate compared to the batteries of Examples 1 to 3.

Claims

1. A method for producing a lithium salt of carboxymethyl cellulose having a degree of carboxymethyl substitution per anhydroglucose unit of 0.5 to 2.0, comprising: Step (A): treating cellulose with lithium hydroxide in a solvent containing 20% ​​by mass or more of water to obtain mercerized cellulose; Step (B): reacting the mercerized cellulose with a carboxymethylating agent in a mixed solvent containing 50 to 99% by mass of an organic solvent based on the total mass of water and the organic solvent to obtain carboxymethyl cellulose, The method for producing carboxymethyl cellulose lithium salt, wherein the amount of lithium ions contained in 1 g of the carboxymethyl cellulose lithium salt is 30,000 to 50,000 ppm.

2. The carboxymethyl cellulose lithium salt has a viscosity of 1,000 to 20,000 mPa s at 25 ° C. measured using a B-type viscometer when made into a 1% by mass aqueous solution. The method for producing carboxymethyl cellulose lithium salt according to claim 1.

3. A method for producing an electrode composition for a non-aqueous electrolyte secondary battery, comprising the step of mixing the carboxymethyl cellulose lithium salt produced by the production method according to claim 1, an electrode active material, and an aqueous solvent.

4. A method for producing an electrode for a non-aqueous electrolyte secondary battery, comprising the step of applying the electrode composition for a non-aqueous electrolyte secondary battery produced by the method according to claim 3 to a current collector.

5. A method for producing a non-aqueous electrolyte secondary battery, comprising the step of laminating an electrode for a non-aqueous electrolyte secondary battery produced by the production method according to claim 4, a separator, and a positive electrode.

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