TWI605634B - Slurry composition for electrode of non-aqueous electrolyte battery, and non-aqueous electrolyte battery anode and non-aqueous electrolyte battery using the same - Google Patents

Description

Slurry composition for nonaqueous electrolyte battery electrode, nonaqueous electrolyte battery negative electrode and nonaqueous electrolyte battery using same

The present invention relates to a slurry composition for a nonaqueous electrolyte battery electrode, and a nonaqueous electrolyte battery negative electrode and a nonaqueous electrolyte battery using the same.

In recent years, mobile terminals such as mobile phones, notebook computers, and tablet type information terminal devices have become popular. Non-aqueous electrolyte batteries are often used in secondary batteries used for power sources of such mobile terminals. Since the mobile terminal is required to be more comfortable to carry, it is rapidly becoming smaller, thinner, lighter, and higher in performance, and can be used in various situations. This trend is currently continuing, and the batteries used in mobile terminals are further required to be smaller, thinner, lighter, and higher in performance.

The nonaqueous electrolyte battery has a structure in which a positive electrode and a negative electrode are disposed via a separator, and such as LiPF ₆ , LiBF ₄ LiTFSI (lithium (bistrifluoromethylsulfonyl sulfenimide)), LiFSI (lithium (difluoride) The lithium salt of the sulfonyl quinone imine)) is dissolved in an electrolytic solution of an organic liquid such as ethylene carbonate and stored in a container.

In the above-mentioned negative electrode and positive electrode, an electrode slurry obtained by dissolving or dispersing a binder and a thickener in water, mixing an active material, and mixing a conductive auxiliary agent (conducting agent) as needed (hereinafter, The only time referred to as a slurry is applied to a current collector, and the water is dried, thereby being combined to form a mixed layer. More specifically, for example, the negative electrode is a carbonaceous material capable of occluding and releasing lithium ions as an active material, and acetylene black of a conductive auxiliary agent, etc., by a binder for a secondary battery electrode. The collectors of copper and the like are combined with each other. On the other hand, in the positive electrode, a binder for a secondary battery electrode is used, and a current-carrying material such as LiCoO ₂ or the like as an active material and, if necessary, a conductive auxiliary agent similar to a negative electrode is bonded to each other.

Heretofore, a diene rubber such as styrene-butadiene rubber or an acrylic resin such as polyacrylic acid has been used as the binder for the aqueous medium (for example, Patent Documents 1 and 2). Examples of the tackifier include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropoxy cellulose, carboxymethyl cellulose ‧ sodium salt (CMC-Na), sodium polyacrylate, and the like. However, CMC-Na is often used therein (for example, Patent Document 3).

However, the diene rubber such as styrene-butadiene rubber has a problem that the adhesion to a metal collector such as copper is low, and the amount of use cannot be reduced in order to improve the adhesion between the collector and the electrode material. Further, there is a problem that the heat generated during charge and discharge is weak and the capacity retention rate is low. In recent years, the demand for the use of the mobile terminal has been increased, and the increase in the charging time has increased, and the increase in the capacity (low resistance), the life (cycle characteristics), and the charging rate (rate characteristic) of the battery have become a top priority. Become an obstacle.

In a non-aqueous electrolyte battery, the battery capacity is affected by the amount of the active material, so it is desirable to increase the active material in a limited space of the battery. Quality, inhibiting the amount of binder and tackifier is effective. Further, since the rate characteristic is also affected by the ease of movement of electrons, the amount of the binder and the tackifier which suppress the non-conductivity and hinder the movement of electrons is effective. However, when the amount of the binder and the tackifier is reduced, the bond between the collector and the electrode material and the active material in the electrode is lowered, and the durability is not only significantly lowered with respect to long-term use (battery life), but also the electrode It will also become brittle. As described above, it has been difficult to improve the battery characteristics such as the battery capacity while maintaining the combination of the collector and the electrode material.

The present invention has been made in view of the above problems, and has an object to realize a function as a binder contained in a slurry composition, that is, it does not damage the bonding property with an active material and a collector, and enhances battery characteristics. .

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2000-67917

Patent Document 2 Japanese Patent Laid-Open Publication No. 2008-288214

Patent Document 3 Japanese Patent Publication No. 2014-13693

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that the above object can be attained by using a slurry composition for a nonaqueous electrolyte battery having the following constitution, and the present invention will be further studied based on this knowledge.

In other words, a slurry composition for a nonaqueous electrolyte battery electrode (hereinafter also referred to simply as a slurry composition) containing a binder composition, an active material, and a solvent according to an aspect of the present invention is characterized in that the activity is The substance is amorphous carbon, and the binder composition comprises an α-olefin-maleic acid copolymerized α-olefin-maleic acid copolymer neutralizing salt, and the copolymer is formed with respect to maleic acid. The degree of neutralization of the carboxylic acid is from 0.3 to 1.0.

According to the present invention, a slurry composition for a nonaqueous electrolyte battery comprising a binder composition, an active material and a solvent which are excellent in bonding property can be obtained, and the battery characteristics of the nonaqueous electrolyte electrode can be improved by using the same.

Form of implementing the invention

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

The binder composition for a nonaqueous electrolyte battery (hereinafter also referred to simply as a binder composition) contained in the slurry composition for a nonaqueous electrolyte battery electrode of the present embodiment is characterized in that it contains an α-olefin and a maleic acid. The copolymerized α-olefin-maleic acid copolymer neutralizes the salt, and the copolymer has a degree of neutralization of 0.3 to 1.0.

In the present embodiment, the α-olefin-maleic acid copolymer copolymerized with the α-olefin and the maleic acid is composed of the α-olefin-based unit (A) and the maleic acid-based unit (B). The components (A) and (B) preferably satisfy (A)/(B) = 1/1 to 1/3 (mole ratio). Further, a linear random copolymer having a weight average molecular weight of 10,000 to 500,000 is preferred.

In the present embodiment, the α-olefin-based unit (A) means a formula -CH ₂ CR ¹ R ² - (wherein R ¹ and R ² may be the same or different from each other, and represent hydrogen and carbon. A composition represented by an alkyl group or an alkenyl group having a number of 1 to 10). Further, the α-olefin used in the present embodiment is a linear or branched olefin having a carbon-carbon unsaturated double bond at the α-position. In particular, an olefin having 2 to 12 carbon atoms is preferred, and an olefin having 2 to 8 carbon atoms is particularly preferred. Typical examples of usable examples include ethylene, propylene, n-butene, isobutylene, n-pentene, isoprene, 2-methyl-1-butene, 3-methyl-1-butene, and hexa Alkene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene, 2,5-pentadiene, 1,4-hexadiene, 2,2,4-trimethyl-1-pentene, etc. . Among them, isobutylene is preferred from the viewpoints of availability, polymerization, and stability of the product. Here, the isobutylene is a mixture containing isobutylene as a main component, and for example, also contains a BB fraction (C4 fraction). These olefins may be used singly or in combination of two or more.

In the present embodiment, the maleic acid-based unit (B) is preferably maleic anhydride, maleic acid or maleic acid monoester (for example, methyl maleate, ethyl maleate, or horse). Maleic acid propyl ester, phenyl maleate, etc.), maleic acid diester (for example, dimethyl maleate, diethyl maleate, dipropyl maleate, diphenyl maleate, etc.) Maleic anhydride derivatives, Malay An acid quinone imine or an N-substituted derivative thereof (for example, quinone iminoate, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide) N-substituted alkyl maleimine N-phenyl horse such as N-n-butylmaleimide, N-tert-butylmaleimide, N-cyclohexylmaleimide or the like N-substituted alkylphenylmaleimide, such as N-iminylmaleimide, N-ethylphenylmaleimide, or N-methoxyphenyl malazone N-substituted alkoxyphenyl maleimide such as imine, N-ethoxyphenyl maleimide, or even such halide (for example, N-chlorophenylmaleimide) , citraconic anhydride, citraconic acid, citraconic acid monoester (eg, methyl citrate, ethyl citrate, propyl citrate, phenyl citrate, etc.), citraconic acid diester (eg , citraconic anhydride derivatives such as dimethyl citrate, diethyl citrate, dipropyl citrate, diphenyl citrate, etc., ruthenium citrate or its N-substituted derivative (eg, citraconium citrate, 2-methyl-N-methyl maleimine, 2-methyl-N-ethyl maleimide, 2-methyl-N-propyl Malay Imine, 2-methyl-N-n-butyl maleimide, 2-methyl-N-tert-butyl maleimide, 2-methyl-N-cyclohexylmaleimide N-substituted alkyl maleimide 2-methyl-N-phenyl maleimine, 2-methyl-N-methylphenyl maleimide, 2-methyl-N 2-ethyl-N-substituted alkylphenylmaleimine such as ethylphenylmaleimide or 2-methyl-N-methoxyphenylmaleimide, 2 a 2-methyl-N-substituted alkoxyphenyl maleimide such as methyl-N-ethoxyphenyl maleimide or the like, or even such a halide (for example, 2-methyl-) N-chlorophenylmaleimide). Among these, maleic anhydride is preferably used from the viewpoints of availability, polymerization rate, and ease of molecular weight adjustment. Further, these maleic acids may be used singly or in combination of a plurality of them. Maleic acid, As described above, the carboxylic acid and the carboxylate formed by neutralization with an alkali salt form a form of a 1,2-dicarboxylic acid or a salt. This form has the function of complementing the heavy metal dissolved by the positive electrode.

The content ratio of each of the above structural units in the copolymer of the present embodiment is preferably in the range of 1/1 to 1/3 in terms of molar ratio (A)/(B). This is because it is advantageous in that it is hydrophilic, water-soluble, and affinity for metal or ions as a high molecular weight body dissolved in water. Particularly preferably, the molar ratio of (A)/(B) is 1/1 or a value close thereto, in which case it is a unit having an α-olefin-based unit, that is, -CH ₂ CR ¹ R ² - Unit, a copolymer that repeats the structure with a maleic acid-based unit.

In order to obtain the mixing ratio of the α-olefins and the maleic acid of the copolymer of the present embodiment, it varies depending on the composition of the intended copolymer, but it is 1 to 3 times the mole of the maleic acid molar number. The number of α-olefins is effective in improving the reaction rate of maleic acid.

The method for producing the copolymer of the present embodiment is not particularly limited, and for example, a copolymer can be obtained by radical polymerization. In this case, as the polymerization catalyst to be used, an azo catalyst such as azobisisobutyronitrile or 1,1-azobiscyclohexane-1-carbonitrile or a benzamidine peroxide or a peroxide is preferred. An organic peroxide catalyst such as cumene. The amount of the polymerization catalyst to be used needs to be in the range of 0.1 to 5 mol% based on the maleic acid, but is preferably 0.5 to 3 mol%. As a method of adding the polymerization catalyst and the monomer, it may be added in a concentrated manner in the initial stage of polymerization, but it is preferably a method of adding the polymerization in the same manner as the polymerization.

In the method for producing a copolymer of the present embodiment, the adjustment of the molecular weight can be appropriately carried out depending on the monomer concentration, the amount of catalyst used, and the polymerization temperature. For example, it is also possible to use a salt of a metal of Group I, II or III of the periodic table, a hydroxide, a halide of a metal of Group IV, a formula of the formula N≡, HN=, H ₂ N- or H ₄ N - A nitrogen compound such as an amine, ammonium acetate or urea, or a thiol or the like is added as a substance which lowers the molecular weight, and is added at the initial stage of polymerization or during the polymerization to adjust the molecular weight of the copolymer. The polymerization temperature is preferably from 40 ° C to 150 ° C, particularly preferably from 60 ° C to 120 ° C. When the polymerization temperature is too high, the resulting copolymer tends to be in the form of a block, and the polymerization pressure is remarkably high. The polymerization time is usually preferably from about 1 to 24 hours, more preferably from 2 to 10 hours. The amount of the polymerization solvent to be used is preferably from 5 to 40% by weight, more preferably from 10 to 30% by weight, based on the obtained copolymer.

As described above, the copolymer of the present embodiment usually has a weight average molecular weight of 10,000 to 500,000. A more preferred weight average molecular weight is from 15,000 to 450,000. When the weight average molecular weight of the copolymer of the present embodiment is less than 10,000, the crystallinity is high and the bonding strength between the particles is small. On the other hand, when it exceeds 500,000, the solubility with respect to water or a solvent becomes small, and it is easy to precipitate.

The weight average molecular weight of the copolymer of the present embodiment can be measured, for example, by a light scattering method or a viscosity method. When the ultimate viscosity ([η]) in dimethylformamide is measured by the viscosity method, the copolymer of the present embodiment preferably has an ultimate viscosity of 0.05 to 1.5. Further, the copolymer of the present embodiment is usually obtained in the form of a powder having a uniform particle size of about 16 to 60 mesh.

In the present embodiment, the neutralized salt of the copolymer preferably reacts with an active substance of a carboxylic acid formed from a maleic acid to form a basic substance. Salt becomes a neutralizing salt. In the α-olefin-maleic acid copolymer and the salt used in the present embodiment, from the viewpoint of the bonding property as a binder, it is preferred to use a basic substance containing a monovalent metal and/or Ammonia is used as the aforementioned basic substance.

In the present embodiment, the amount of the basic substance containing a monovalent metal and/or ammonia is not particularly limited, and may be appropriately selected depending on the purpose of use, etc., but usually it is preferably each of the maleic acid copolymers. The maleic acid unit 1 mole is in an amount of 0.6 to 2.0 moles. The degree of neutralization of the binder composition of the present embodiment can be adjusted to a predetermined range as long as it is used as described above. Further, when the amount of the basic substance containing a monovalent metal is preferably such that the amount of the maleic acid unit in the maleic acid copolymer is from 0.8 to 1.8 mol, the alkali can be obtained. A small amount of water-soluble copolymer salt remains.

The reaction of an α-olefin-maleic acid copolymer, an alkali substance containing a monovalent metal, and/or an amine such as ammonia can be carried out according to a usual method, but is carried out in the presence of water, and the α-olefin is used. The method of obtaining a salt of a maleic acid copolymer and a salt as an aqueous solution is simple and preferable.

Examples of the basic substance containing a metal which is monovalent in the present embodiment include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; sodium carbonate, potassium carbonate, and the like. An alkali metal carbonate; an alkali metal acetate such as sodium acetate or potassium acetate; or an alkali metal phosphate such as trisodium phosphate. Examples of the amine such as ammonia include a primary amine such as ammonia, methylamine, ethylamine, butylamine or octylamine, a secondary amine such as dimethylamine, diethylamine or dibutylamine, trimethylamine or the like. Grade III amines such as ethylamine and tributylamine, ethylenediamine, butanediamine, diethylenediamine, and triamethylene A polyamine such as an amine or a polyethyleneimine. Among these, ammonia, lithium hydroxide, sodium hydroxide, and potassium hydroxide are particularly preferred. In particular, as the binder for the nonaqueous electrolyte battery, ammonia or lithium hydroxide is preferably used. The basic substance and/or ammonia containing a monovalent metal may be used singly or in combination of two or more. In addition, a neutralized salt of an α-olefin-maleic acid copolymer can be prepared by using a basic substance such as a hydroxide containing an alkali metal such as sodium hydroxide in combination, insofar as it does not adversely affect the battery performance.

Next, in the present embodiment, the copolymer of the binder composition has a degree of neutralization of carboxylic acid formed from maleic acid of 0.3 to 1.0. When the degree of neutralization is less than 0.3, the solubility in water or a solvent is small and it is easy to precipitate, and slurry coating becomes difficult. Further, when the degree of neutralization exceeds 1.0, the neutralized alkaline substance is excessively present in the slurry, and therefore, it is a component of a resistance component. More preferably, the aforementioned degree of neutralization is preferably in the range of 0.4 to 0.8. Thereby, a slurry composition having better coatability can be obtained.

In the present embodiment, a method such as titration with an alkali, infrared spectroscopy, or NMR spectroscopy may be used for the degree of neutralization. However, in order to easily and accurately measure the neutralization point, it is preferred to carry out titration with a base. The specific titration method is not particularly limited, but water which is soluble in impurities such as ion-exchanged water is neutralized by an alkaline substance such as lithium hydroxide, sodium hydroxide or potassium hydroxide. Implementation. The indicator for the neutralization point is not particularly limited, and an indicator such as phenolphthalein or the like which is pH-indicated with a base can be used.

In the present embodiment, the degree of neutralization of the binder composition can be adjusted, for example, by adjusting the degree of neutralization of the binder composition, and the degree of neutralization of the aqueous solution in which the binder composition is dissolved can be directly adjusted. Specifically, for example, the adjustment of the degree of neutralization can be adjusted by adjusting the amount of addition of a basic substance (ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.) containing a monovalent metal as described above. The foregoing range is not limited thereto. Further, specifically, as described above, it is preferred to add an alkaline substance containing a monovalent metal and/or an amount of 0.6 to 2.0 mol per maleic acid unit in the maleic acid copolymer. Or ammonia, whereby it can be adjusted to the aforementioned range. More preferably, the amount of each maleic acid unit in the maleic acid copolymer is 0.6 to 1.8 moles, and an alkaline substance containing a monovalent metal and/or ammonia is added, whereby the adjustment can be more surely adjusted. For the aforementioned range.

Next, in the present embodiment, the ring opening ratio of the copolymer indicates the hydrolysis rate of the maleic anhydride-based site which is polymerized with the α-olefin when maleic anhydride is used as the maleic acid. In the copolymer of the present embodiment, the ring opening ratio is preferably from 60 to 100%, more preferably from 70% to 100%, still more preferably from 80 to 100%. When the ring opening ratio is too low, the degree of freedom of the structure of the copolymer becomes small, and the stretchability is lacking. Therefore, the force of the adjacent electrode particles becomes smaller, which is less preferable. Further, there is a problem that the affinity with water is low and the solubility is insufficient. The ring opening ratio can be determined, for example, by using hydrogen at the α position of maleic anhydride as a reference, and determining the ratio of hydrogen at the α position of the ring-opened maleic acid by 1H-NMR, and the carbonyl group of maleic acid can also be used. The carbonyl group derived from the ring-opened maleic anhydride is determined by IR measurement.

The slurry composition for a nonaqueous electrolyte battery according to the present embodiment is characterized in that it contains amorphous carbon and a solvent which are active materials in addition to the above-mentioned binder composition.

The amorphous carbon which is an active material added to the slurry composition for a nonaqueous electrolyte battery of the present embodiment (hereinafter sometimes simply referred to as an active material) may, for example, be carbon black, activated carbon, carbon fiber or hard carbon. , soft carbon, porous carbon, and composite materials of metal oxides and such amorphous carbon. By using the amorphous carbon as described above as an active material, lithium is inserted into a portion where the graphene layer is distorted or the laminate is not developed, so that a high capacity of crystalline graphite or higher can be achieved. advantage.

In the slurry composition for a nonaqueous electrolyte battery, the amount of the neutralized salt of the α-olefin-maleic acid copolymer is preferably 0.1 to 20 with respect to 100 parts by weight of the amorphous carbon of the active material. The parts by weight are more preferably 0.3 to 10 parts by weight, still more preferably 0.5 to 8 parts by weight. When the amount of the copolymer is too small, the viscosity of the slurry for the electrode is too low and the thickness of the mixed layer is thin. Conversely, when the amount of the copolymer is too large, the discharge capacity may be lowered.

On the other hand, the amount of the solvent in the slurry composition for a nonaqueous electrolyte battery is usually preferably from 10 to 150 parts by weight, more preferably from 30 to 130 parts by weight based on 100 parts by weight of the amorphous carbon of the active material. Share.

The solvent in the slurry composition for a nonaqueous electrolyte battery of the present embodiment may, for example, be an alcohol such as water, methanol, ethanol, propanol or 2-propanol, tetrahydrofuran or the like. a cyclic ether such as an alkane, N,N-dimethylformamide, an amine such as N,N-dimethylacetamide, N-methylpyrrolidone or N-ethylpyrrolidone Such as cyclic guanamines, quinones such as dimethyl hydrazine and the like. Among these, water is preferably used from the viewpoint of safety.

In addition, when water is used as the solvent of the slurry composition for a non-aqueous electrolyte battery of the present embodiment, the organic solvent shown below may be used in an amount of preferably 20% by weight or less based on the total amount of the solvent. The organic solvent as described above is preferably a hydrocarbon having a boiling point of from 100 ° C to 300 ° C at normal pressure, and examples thereof include hydrocarbons such as n-dodecane; 2-ethyl-1-hexanol and 1-oxime; An alcohol such as an alcohol; an ester of γ-butyrolactone or methyl lactate; an amide such as N-methylpyrrolidone, N,N-dimethylacetamide or dimethylformamide An organic dispersion medium such as hydrazine, hydrazine or the like.

In the present embodiment, a tackifier or a conductive auxiliary agent may be further added to the slurry composition for a nonaqueous electrolyte battery.

The tackifier which can be added is not particularly limited, and various alcohols can be used, in particular, polyvinyl alcohol and modified products thereof, polysaccharides such as cellulose or starch.

The amount of the tackifier to be blended as needed in the slurry composition for a non-aqueous electrolyte battery is preferably about 0.1 to 4 parts by weight, more preferably about 0.3%, based on 100 parts by weight of the amorphous carbon of the active material. 3 parts by weight, further preferably 0.5 to 2 parts by weight. When the tackifier is too small, the viscosity of the slurry for a nonaqueous electrolyte battery is too low and the thickness of the mixed layer is thin. Conversely, when the tackifier is too large, the discharge capacity may be lowered.

In addition, examples of the conductive auxiliary agent to be blended in the slurry composition for a nonaqueous electrolyte battery include metal powder, conductive polymer, and acetylene black. The amount of the conductive auxiliary agent to be used is usually preferably from 0.3 to 10 parts by weight, more preferably from 0.5 to 7 parts by weight, per 100 parts by weight of the active material.

In the present embodiment, the nonaqueous electrolyte battery negative electrode is characterized in that a current collector is combined with a mixed layer containing at least the slurry composition for a nonaqueous electrolyte battery of the present embodiment.

The above-mentioned negative electrode can be formed by applying the slurry composition for a nonaqueous electrolyte battery described above to a current collector, and then removing the solvent by drying or the like.

The current collector used in the negative electrode of the nonaqueous electrolyte battery of the present embodiment is not particularly limited as long as it is made of a conductive material. For example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, or the like can be used. Metal materials such as gold and platinum. These may be used alone or in combination of two or more kinds in any ratio.

In particular, when copper is used as the negative electrode current collector, the effect of the slurry for a nonaqueous electrolyte battery of the present invention can be exhibited most. The shape of the current collector is not particularly limited, but is usually preferably a sheet having a thickness of about 0.001 to 0.5 mm.

The method of applying the slurry for a nonaqueous electrolyte battery to the current collector is not particularly limited. Examples thereof include a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, and a brush coating method. The amount of the coating is not particularly limited, but generally, the thickness of the mixed layer containing the active material, the conductive auxiliary agent, the binder, and the tackifier formed by removing the solvent or the dispersion medium by drying or the like is performed. It is preferably 0.005 to 5 mm, more preferably 0.01 to 2 mm.

The drying method of the solvent such as water contained in the slurry composition for a non-aqueous electrolyte battery is not particularly limited, and examples thereof include aeration drying by warm air, hot air, and low-humidity wind; vacuum drying; infrared rays and far The irradiation line such as infrared rays or electron beams is dried. The drying conditions are adjusted so that the solvent can be cracked in the active material layer by stress concentration, and the active material layer is not peeled off from the current collector, so that the solvent can be removed as quickly as possible. Further, in order to increase the density of the active material of the electrode, it is effective to pressurize the collected current collector. As a pressurization method, the method of a press press, a roll press, etc. are mentioned.

Furthermore, the present invention also includes a nonaqueous electrolyte battery including the negative electrode of the nonaqueous electrolyte battery, the positive electrode, and the electrolytic solution.

As the positive electrode of the present embodiment, a positive electrode which is generally used in a nonaqueous electrolyte battery can be used without particular limitation. For example, as the positive electrode active material, TiS ₂ , TiS ₃ , amorphous MoS ₃ , Cu ₂ V ₂ O ₃ , amorphous V ₂ OP ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O _{13 ,} or the like is used. A transition metal oxide or a lithium-containing composite metal oxide such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ or LiMn ₂ O ₄ . Further, the positive electrode active material, the same conductive auxiliary agent as the above negative electrode, and SBR, NBR, acrylic rubber, hydroxyethyl cellulose may be mixed with water or a solvent having a boiling point of 100 ° C or more and 300 ° C or less. A slurry for a positive electrode prepared by using a binder such as carboxymethylcellulose or polyvinylidene fluoride is applied to, for example, a positive electrode current collector such as aluminum, and the solvent is dried to obtain a positive electrode.

Further, in the nonaqueous electrolyte battery of the present embodiment, an electrolytic solution in which an electrolyte is dissolved in a solvent can be used. The electrolyte solution may be a liquid or a gel as long as it is a user of a normal non-aqueous electrolyte battery, and may be appropriately selected as a battery function depending on the type of the negative electrode active material or the positive electrode active material. As a specific electrolyte, for example, a conventionally known lithium salt can be used, and examples thereof include LiClO ₄ , LiBF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , and LiAlCl. ₄ , LiCl, LiBr, LiB(C ₂ H ₅ ) ₄ , CF ₃ SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, low grade An aliphatic lithium carboxylate or the like.

The solvent (electrolyte solvent) which dissolves the electrolyte as described above is not particularly limited. Specific examples thereof include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, and diethyl carbonate; lactones such as γ-butyrolactone; and trimethoxymethane; An ether such as 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran or 2-methyltetrahydrofuran; an anthracene such as dimethyl hydrazine; 1,3-dioxane; An oxolane such as 1,3-dioxolane or 4-methyl-1,3-dioxolane; a nitrogen-containing compound such as acetonitrile or nitromethane; Organic acid esters such as ester, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, etc.; inorganic acid esters such as triethyl phosphate, dimethyl carbonate, diethyl carbonate, etc. Diethylene glycol dimethyl ether; triethylene glycol dimethyl ether; cyclobutyl hydrazine; 3-methyl-2-oxazolidinone, etc. a sultone such as 1,3-propanesultone, 1,4-butane sultone or naphthalene sultone, etc., which may be used alone or in combination of two or more. And use. When a gel-like electrolyte solution is used, a nitrile polymer, an acrylic polymer, a fluorine-based polymer, an alkylene oxide-based polymer or the like can be added as a gelling agent.

The method of producing the nonaqueous electrolyte battery of the present embodiment is not particularly limited, and for example, the following production methods can be exemplified. That is, the negative electrode and the positive electrode are separated by a separator such as a polypropylene porous film. The stack is crimped, folded, etc. in accordance with the shape of the battery, placed in a battery container, and the electrolyte is injected and sealed. The shape of the battery may be any known coin type, button type, sheet type, cylinder type, square type, flat type, or the like.

The nonaqueous electrolyte battery of the present embodiment is a battery that can improve both the adhesion and the battery characteristics, and is useful for various applications. For example, it is also useful as a battery used in mobile terminals that require miniaturization, thinning, weight reduction, and high performance.

In the present specification, as described above, various aspects of the technique are disclosed, and the main techniques thereof are summarized below.

A slurry composition for a nonaqueous electrolyte battery electrode (hereinafter also referred to simply as a slurry composition) containing a binder composition, an active material, and a solvent according to an aspect of the present invention, characterized in that the active material is non- a crystalline carbon, the binder composition comprising an α-olefin-maleic acid-copolymerized α-olefin-maleic acid copolymer neutralizing salt, and the copolymer is relative to a carboxylic acid formed from a maleic acid The degree of neutralization is 0.3~1.0.

According to the configuration as described above, it is possible to provide a slurry composition which does not impair the bonding property between the collectors and the active material, and which can improve the battery characteristics, and has no need to use a tackifier or a dispersant. The advantages.

A nonaqueous electrolyte battery negative electrode according to another aspect of the present invention is characterized in that a current collector is combined with a mixed layer containing at least the slurry composition for a nonaqueous electrolyte battery.

Further, a nonaqueous electrolyte battery according to another aspect of the present invention is characterized by comprising the above negative electrode, a positive electrode, and an electrolytic solution.

[Examples]

The embodiments of the present invention are described below, but the present invention is not limited thereto.

(Example 1)

<Binder composition>

A water-soluble lithium-modified isobutylene-maleic anhydride copolymerized resin (average molecular weight: 325,000, degree of neutralization 1.0, ring opening ratio: 100%) 25 g (0.16 mol) was used as a binder composition to prepare a 10 wt% aqueous solution, and the following Used for the test. The adjustment of the degree of neutralization was carried out by adding 2.0 equivalents (0.320 mol) of lithium hydroxide to the maleic acid unit in the maleic acid copolymer.

<Production of Active Material (Hard Carbon)>

The coconut shell was pulverized and subjected to dry distillation at 500 ° C to obtain coconut shell carbon having a particle diameter of 2.360 to 0.850 mm (containing 98% by weight of particles having a particle diameter of 2.360 to 0.850 mm). With respect to 100 g of coconut shell carbon, nitrogen gas containing 1% by volume of hydrogen chloride gas was supplied at a flow rate of 10 L/min, and gas phase deashing treatment was performed at 870 ° C for 30 minutes. Thereafter, only the supply of hydrogen chloride gas was stopped, nitrogen gas was supplied at a flow rate of 10 L/min, and gas phase deacidification treatment was further carried out at 900 ° C for 30 minutes to obtain a carbon precursor.

The carbon precursor obtained was coarsely pulverized to a particle diameter of 10 μm using a ball mill, and then pulverized and classified by using a compact jet mill (Co-Jet System α-mkIII, manufactured by Seishin Enterprise Co., Ltd.) to obtain an average particle diameter of 9.6. A carbon precursor of μm. Mixing this carbon precursor with 9.1g and polystyrene (Limited Water Products) The company has an average particle size of 400 μm and a residual carbon ratio of 1.2%) of 0.9 g. 10 g of this mixture was placed in a graphite sheath (100 mm in length, 100 mm in width, and 50 mm in height), and was heated at a temperature increase rate of 60 ° C per minute in a high-speed heating furnace manufactured by MOTOYAMA Co., Ltd. at a nitrogen flow rate of 5 L per minute. After 1320 ° C, it was kept for 11 minutes and naturally cooled, whereby hard carbon was produced.

<Preparation of a slurry composition for a nonaqueous electrolyte battery>

The 10 wt% aqueous solution of the above-mentioned non-aqueous electrolyte battery binder composition was put into a dedicated container at a solid content of 6.38 parts by weight with respect to 100 parts by weight of the hard carbon as the active material, and a planetary stirrer (ARE-250, manufactured by THINKY) was used. ) Perform a match. In order to adjust the viscosity of the slurry, water is added during the kneading, and the electrode coating slurry is prepared by re-coupling. The composition ratio of the active material to the binder in the slurry is, in terms of solid content, a hard carbon powder: a binder composition = 100: 6.38. Further, the water as a solvent was 46.8 wt% based on the active material.

<Measurement of pH of a binder composition for nonaqueous electrolyte batteries>

The pH of the 10 wt% aqueous solution of the above-mentioned binder composition was measured using a glass electrode pH meter (D-51, manufactured by Horiba). The results are shown in Table 1 below.

<Production of Negative Electrode for Nonaqueous Electrolyte Battery>

The obtained slurry was applied to a copper foil (CST8G, manufactured by Fukuda Metal Foil Co., Ltd.) of a current collector using a bar coater (T101, manufactured by Matsuo Industries Co., Ltd.), and dried at 80 ° C in a hot air dryer (manufactured by YAMATO Scientific Co., Ltd.). After drying for 30 minutes at a time, rolling treatment was carried out using a roll press (manufactured by Takara). After that, after punching as a battery electrode (φ14 mm), The electrode for a coin battery was produced by secondary drying at 120 ° C for 3 hours under reduced pressure.

<Measurement of Thickness of Battery Negative Electrode>

The weight and thickness of the coated electrode for a battery obtained above (the thickness of the active material layer was about 50 μm, and the weight of the active material was about 12 mg). In the measurement of the thickness, a constant pressure thickness measuring device (manufactured by TECLOCK Co., Ltd.) was used, and the results of measurement of four electrodes and three different points were 48 ± 0.5 μm.

<electrode coating property>

With respect to the electrode coating property, the unevenness of the electrode film thickness was used as an index, and four electrodes and three different points were measured. Then, when the unevenness is 0 to ±0.5 μm, the evaluation is ◎, and when it is ±0.5 to ±1.0 μm, the evaluation is ○, and when it is ±1.0 to ±2.0 μm, it is evaluated as Δ, ±2.0 μm or more. In the case of evaluation, it is evaluated as ×. The results are shown in Table 1 below.

<Measurement of Peel Strength of Negative Electrode for Nonaqueous Electrolyte Battery>

The strength at the time of peeling off the electrode from the copper foil which is the collector was measured. The peel strength was measured using a load of 50 N (manufactured by IMADA Co., Ltd.) to measure the 180° peel strength. The slurry-coated surface of the coated electrode for a battery obtained above and a stainless steel plate were bonded together using a double-sided tape (double-sided tape manufactured by Nichiban), and 180° peel strength (peel width: 10 mm, peeling speed: 100 mm/min) was measured. The above results are shown in Table 1 below.

<Production of battery>

The coated electrode for a battery obtained above was transferred to a glove box (manufactured by Miho Seisakusho Co., Ltd.) under an argon atmosphere. A metal lithium foil (thickness: 0.2 mm, φ16 mm) was used for the positive electrode. Further, a polypropylene type (Celgard #2400, manufactured by Polypore) was used as a separator, and a mixed solvent system of ethylene carbonate (EC) and diethyl carbonate (DEC) of lithium hexafluorophosphate (LiPF ₆ ) was used as the electrolytic solution ( 1M-LiPF ₆ , EC/DEC = 1/1 vol%) was injected to make a coin battery (type 2032).

<Evaluation method: charge and discharge characteristics test>

The produced coin battery was subjected to a charge and discharge test using a commercially available charge and discharge tester (TOSCAT 3100, manufactured by Toyo Systems Co., Ltd.). The coin battery was placed in a thermostat at 25 ° C, charged to 0 V with respect to the lithium potential, and subjected to constant current charging of 0.1 C (about 0.5 mA/cm ² ) with respect to the mass of the active material, and further implemented with respect to the lithium potential. A constant voltage of 0V is charged up to a current of 0.02 mA. The capacity at this time was taken as the charging capacity (mAh/g). Next, a constant current discharge of 0.1 C (about 0.5 mA/cm ² ) was carried out until 1.5 V with respect to the lithium potential, and the capacity at this time was taken as the discharge capacity (mAh/g). The difference between the initial discharge capacity and the charge capacity was defined as the irreversible capacity, and the percentage of the discharge capacity/charge capacity was taken as the charge and discharge efficiency. The DC resistance of the coin battery is the resistance value after one charge (full charge). The above results are shown in Table 1 below.

The discharge capacity retention rate (%) of the coin battery was determined as the ratio of the discharge capacity of the 20th time to the first discharge capacity using the above-described charge and discharge conditions. The results are shown in Table 1 below.

(Example 2)

A 10 wt% aqueous solution of a water-soluble lithium-modified isobutylene-maleic anhydride copolymer resin (having an average molecular weight of 325,000, a degree of neutralization of 0.5, and a ring-opening rate of 96%) was prepared as a binder composition, and was used in the following test. Neutralization adjustment, by comparison with horses in maleic acid copolymers The acid unit was added with 1.0 equivalent (0.160 mol) of lithium hydroxide. The slurry for a nonaqueous electrolyte battery was produced in the same manner as in the above Example 1. Further, a negative electrode was coated by the same method as in the above Example 1, to obtain a coin battery, and a charge and discharge property test was performed. Further, 180° peel strength measurement was carried out by the same method as in Example 1 using a coating electrode. The film thickness measured by the same method as in the above Example 1 was 47 ± 0.3 μm. The above results are shown in Table 1 below.

(Example 3)

A 10 wt% aqueous solution of a water-soluble lithium-modified isobutylene-maleic anhydride copolymer resin (having an average molecular weight of 325,000, a degree of neutralization of 0.3, and a ring-opening ratio of 82%) was prepared as a binder composition, and was used in the following test. The adjustment of the degree of neutralization was carried out by adding 0.60 equivalent (0.096 mol) of lithium hydroxide to the maleic acid unit in the maleic acid copolymer. The slurry for a nonaqueous electrolyte battery was produced in the same manner as in the above Example 1. Further, a negative electrode was coated by the same method as in the above Example 1, to obtain a coin battery, and a charge and discharge property test was performed. Further, 180° peel strength measurement was carried out by the same method as in Example 1 using a coating electrode. The film thickness measured by the same method as in the above Example 1 was 46 ± 1.0 μm. The above results are shown in Table 1 below.

(Example 4)

A 10 wt% aqueous solution of a water-soluble lithium-modified isobutylene-maleic anhydride copolymer resin (having an average molecular weight of 180,000, a degree of neutralization of 0.5, and a ring-opening ratio of 100%) was prepared as a binder composition, and was used in the following test. The adjustment of the degree of neutralization was carried out by adding 1.0 equivalent (0.160 mol) of lithium hydroxide to the maleic acid unit in the maleic acid copolymer. will The slurry for a nonaqueous electrolyte battery was produced in the same manner as in the above Example 1. Further, a negative electrode was coated by the same method as in the above Example 1, to obtain a coin battery, and a charge and discharge property test was performed. Further, 180° peel strength measurement was carried out by the same method as in Example 1 using a coating electrode. The film thickness measured by the same method as in the above Example 1 was 47 ± 1.0 μm. The above results are shown in Table 1 below.

(Example 5)

A 10 wt% aqueous solution of a water-soluble lithium-modified isobutylene-maleic anhydride copolymer resin (having an average molecular weight of 180,000, a degree of neutralization of 0.75, and a ring-opening ratio of 100%) was prepared as a binder composition, and was used in the following test. The adjustment of the degree of neutralization was carried out by adding 1.5 equivalents (0.24 mol) of lithium hydroxide to the maleic acid unit in the maleic acid copolymer. The slurry for a nonaqueous electrolyte battery was produced in the same manner as in the above Example 1. Further, a negative electrode was coated by the same method as in the above Example 1, to obtain a coin battery, and a charge and discharge property test was performed. Further, 180° peel strength measurement was carried out by the same method as in Example 1 using a coating electrode. The film thickness measured by the same method as in the above Example 1 was 46 ± 2.0 μm. The above results are shown in Table 1 below.

(Comparative Example 1)

Although it is desired to obtain a water-soluble lithium-modified isobutylene-maleic anhydride copolymer resin having a degree of neutralization of 0.2 by adding 0.4 equivalent (0.064 mol) of lithium hydroxide to the maleic acid unit in the maleic acid copolymer ( The average molecular weight is 325,000), but the solubility is low and a water-soluble resin cannot be obtained. Therefore, it is impossible to manufacture a binder composition.

(Comparative Example 2)

With respect to 100 parts by weight of artificial graphite (FNS-1, manufactured by Chinese cedar) as an active material, a 10 w% aqueous solution of the binder composition described in Example 1 was used as a conductive additive (6.45 parts by weight) and as a conductive auxiliary agent ( Super-P (manufactured by TIMCAL Co., Ltd.), which is a conductive agent, was placed in a special container at a solid content of 1.08 parts by weight to prepare a slurry for electrode coating. The composition ratio of the active material to the binder in the slurry is, in terms of solid content, artificial graphite: conductive additive: binder composition = 100: 1.08: 6.45. Further, the water as a solvent was 48.4% by weight based on the active material. Further, a coated negative electrode was produced by the same method as in the above Example 1, and a mixed solvent system (1M-) in which vinylene carbonate (VC) was added to ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used. LiPF ₆ , EC/EMC = 3/7 vol%, VC 2%) As a electrolytic solution, a coin battery was obtained, and a charge and discharge characteristic test was performed. Further, 180° peel strength measurement was carried out by the same method as in Example 1 using a coating electrode. The film thickness measured by the same method as in the above Example 1 was 42 ± 0.4 μm. The above results are shown in Table 1 below.

(examine)

The slurry compositions of Examples 1 to 5 in which the degree of neutralization of the binder composition is in the range of 0.3 to 1.0 can exhibit very good adhesion and coating properties even without adjusting the viscosity by a tackifier or the like. Then, as is apparent from Table 1, in the batteries of Examples 1 to 5, it was revealed that the reduction in resistance and the high discharge capacity retention ratio were achieved. Further, in Example 2 in which the degree of neutralization of the binder composition was in the range of 0.4 to 0.8, the coating property was extremely excellent. On the other hand, in the comparative example 1 in which the degree of neutralization did not satisfy the range of the present invention, the binder composition could not be produced. Further, in Comparative Example 2 in which artificial graphite was used as the active material, the adhesion was low, and the electrode was easily peeled off during charge and discharge, and the capacity retention rate was low.

The application is based on Japanese Patent Application No. 2015-156095, filed on Aug. 6, 2015, the content of which is hereby incorporated herein.

In order to present the present invention, the present invention will be described as appropriate and fully described with reference to the drawings and the like. However, as long as it is generally known in the art, it can be easily changed and/or The above embodiment is modified. Therefore, the modified form or the modified form that is carried out by a person having ordinary skill in the art is not limited to the level of the right to the claims of the claims. The scope of the rights to the claim.

[Industrial use]

The present invention has wide industrial applicability in the technical field of nonaqueous electrolyte batteries.

Claims (3)

A slurry composition for a nonaqueous electrolyte battery electrode, comprising a binder composition, an active material, and a solvent for a nonaqueous electrolyte battery electrode slurry composition, wherein the active material is amorphous carbon, and the binder composition comprises The isobutylene-maleic acid copolymerized isobutylene-maleic acid copolymer neutralizes the salt, and the copolymer has a degree of neutralization of 0.3 to 1.0 with respect to the carboxylic acid formed from the maleic acid. A nonaqueous electrolyte battery negative electrode comprising a mixed layer containing the slurry composition of claim 1 and a current collector. A nonaqueous electrolyte battery having the negative electrode of the nonaqueous electrolyte battery as claimed in claim 2.