WO2018101134A1

WO2018101134A1 - Binder composition for nonaqueous electrolyte battery electrode, hydrogel using binder composition as raw material, slurry composition for nonaqueous electrolyte battery electrode using same, nonaqueous electrolyte battery negative electrode, and nonaqueous electrolyte battery

Info

Publication number: WO2018101134A1
Application number: PCT/JP2017/041909
Authority: WO
Inventors: 有紀太田; 俊充田中; 良太小宮; 俊相趙; 岩崎　秀治
Original assignee: 株式会社クラレ
Priority date: 2016-11-29
Filing date: 2017-11-21
Publication date: 2018-06-07
Also published as: JPWO2018101134A1; CN110024191A; KR20190082977A; TW201830757A

Abstract

The present invention pertains to: a binder composition for a nonaqueous electrolyte battery electrode, the composition containing a crosslinking agent and a neutralized salt of an α-olefin-maleic acid copolymer obtained through copolymerization of an α-olefin and maleic acid; a slurry composition that is for a nonaqueous electrolyte battery electrode and that uses the binder composition; a nonaqueous electrolyte battery negative electrode; a nonaqueous electrolyte battery, etc.

Description

Non-aqueous electrolyte battery electrode binder composition, hydrogel using the same, slurry composition for non-aqueous electrolyte battery electrode using the same, non-aqueous electrolyte battery negative electrode, and non-aqueous electrolyte battery

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

In recent years, mobile terminals such as mobile phones, notebook computers, pad-type information terminal devices have been widely used. Lithium ion secondary batteries are frequently used as secondary batteries used for the power sources of these portable terminals. Since portable terminals are required to have more comfortable portability, miniaturization, thinning, weight reduction, and high performance have rapidly progressed, and have come to be used in various places. This trend continues today, and batteries used in mobile terminals are further required to be smaller, thinner, lighter, and higher in performance.

A non-aqueous electrolyte battery such as a lithium ion secondary battery has a positive electrode and a negative electrode installed via a separator, and LiPF ₆ , LiBF ₄ LiTFSI (lithium (bistrifluoromethylsulfonylimide)), LiFSI (lithium (bisfluorosulfonylimide). )) And a lithium salt dissolved in an organic liquid such as ethylene carbonate in a container.

The negative electrode and the positive electrode are usually obtained by dissolving or dispersing a binder and a thickener in water and mixing an active material, a conductive aid (conductivity imparting agent) and the like with this, Hereinafter, it may be simply formed as a mixed layer by coating the current collector on the current collector and drying the water. More specifically, for example, for the negative electrode, a carbonaceous material capable of occluding and releasing lithium ions, which is an active material, and, if necessary, acetylene black, a conductive auxiliary agent, are secondary to a current collector such as copper. They are bound together by a binder for battery electrodes. On the other hand, for the positive electrode, LiCoO ₂ that is an active material and, if necessary, a conductive aid similar to that of the negative electrode are bound to a current collector such as aluminum using a secondary battery electrode binder. Is.

So far, diene rubbers such as styrene-butadiene rubber and acrylics such as polyacrylic acid have been used as binders for aqueous media (for example, Patent Documents 1 and 2). Examples of the thickener include methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropoxycellulose, carboxymethylcellulose sodium salt (CMC-Na), sodium polyacrylate, etc. Among them, CMC-Na is often used. (For example, patent document 3).

However, diene rubbers such as styrene-butadiene rubber have low adhesion to metal collectors such as copper, and there is a problem that the amount used cannot be reduced to increase the adhesion between the collector and the electrode material. . In addition, there is a problem that the capacity maintenance rate is low due to weakness against heat generated during charging and discharging. On the other hand, polyacrylic acid soda exhibits higher adhesion than styrene-butadiene rubber, but has a problem that the electrode is easily cracked because the electric resistance is high and the electrode becomes harder and less tough. Recently, demands for extending the usage time of mobile devices and shortening charging time have increased, and there is an urgent need to improve battery capacity (low resistance), life (cycle characteristics), and charging speed (rate characteristics). In particular, it is an obstacle. *

In a non-aqueous electrolyte battery, since the battery capacity is affected by the amount of active material, it is effective to suppress the amount of binder and thickener in order to increase the active material in a limited space of the battery. Moreover, since the rate characteristics are also affected by the ease of electron movement, it is effective to suppress the amount of binder and thickener that are non-conductive and prevent electron movement. However, if the amount of the binder and the thickener is reduced, the binding property between the collector electrode and the electrode material and the active material in the electrode is lowered, and the durability (battery life) for long-term use is significantly reduced. However, the electrode becomes brittle. Thus, it has been difficult to improve battery characteristics such as battery capacity while maintaining the binding property between the collector electrode and the electrode material and maintaining the toughness as an electrode.

The present invention has been made in view of the above-described problems, and an object thereof is to improve battery characteristics in a nonaqueous electrolyte battery without impairing the function as a binder, that is, the toughness as an electrode.

Furthermore, another object of the present invention is to improve battery characteristics in a non-aqueous electrolyte battery without impairing the binding property between the active materials and the collector electrode.

JP 2000-67917 A JP 2008-288214 A Japanese Patent Laid-Open No. 2014-13693

As a result of diligent research to solve the above problems, the present inventors have found that the above object can be achieved by using a binder composition for a nonaqueous electrolyte battery electrode having the following constitution, and further investigation based on this finding Thus, the present invention was completed.

That is, the binder composition for a nonaqueous electrolyte battery electrode according to one aspect of the present invention (hereinafter also simply referred to as a binder composition) is an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid. A binder composition for a non-aqueous electrolyte battery electrode having a structure in which a neutralized salt of a coalescence is cross-linked with polyamines, and a viscosity of an aqueous solution containing 10% by weight of the binder composition at 25 ° C. and a shear rate of 40 s ⁻¹ Is 1800 mPa · s to 15000 mPa · s.

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 electrode according to this embodiment has a structure in which a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid is crosslinked with a polyamine. A binder composition for a non-aqueous electrolyte battery electrode, wherein an aqueous solution containing 10% by weight of the binder composition has a viscosity of 1800 mPa · s to 15000 mPa · s at 25 ° C. and a shear rate of 40 s ⁻¹ . .

According to such a configuration, a binder composition for a non-aqueous electrolyte battery electrode having binding properties and toughness can be obtained, and further, improvement of battery characteristics of the non-aqueous electrolyte battery can be realized using the binder composition. Can do.

In this embodiment, an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid is composed of a unit (A) based on the α-olefin and a unit (B) based on the maleic acid. The components (A) and (B) preferably satisfy (A) / (B) (molar ratio) of 1/1 to 1/3. A linear random copolymer having an average molecular weight of 10,000 to 500,000 is preferable.

In the present embodiment, the unit (A) based on α-olefins is represented by the general formula —CH ₂ CR ¹ R ² — (wherein R ¹ and R ² may be the same or different from each other, hydrogen Represents an alkyl or alkenyl group having 1 to 10 carbon atoms). The α-olefin used in this embodiment is a linear or branched olefin having a carbon-carbon unsaturated double bond at the α-position. In particular, olefins having 2 to 12 carbon atoms, particularly 2 to 8 carbon atoms are preferred. Representative examples that can be used include ethylene, propylene, n-butylene, isobutylene, n-pentene, isoprene, 2-methyl-1-butene, 3-methyl-1-butene, n-hexene, 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, styrene, α-methylstyrene, paramethylstyrene, methyl vinyl ether, ethyl vinyl ether and the like. Among these, isobutylene is particularly preferable from the viewpoints of availability, polysynthesis, and product stability. Here, the isobutylene includes a mixture containing isobutylene as a main component, for example, a BB fraction (C4 fraction). These olefins may be used alone or in combination of two or more.

In the present embodiment, maleic anhydride, maleic acid, maleic acid monoester (for example, methyl maleate, ethyl maleate, propyl maleate, phenyl maleate, etc.), maleic acid, as the unit (B) based on maleic acids Maleic anhydride derivatives such as diesters (eg dimethyl maleate, diethyl maleate, dipropyl maleate, diphenyl maleate etc.), maleic imides or N-substituted derivatives thereof (eg maleic imide, N-methylmaleimide, N N-substituted alkylmaleimides such as ethylmaleimide, N-propylmaleimide, Nn-butylmaleimide, Nt-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-ethyl Phenyl male N-substituted alkylphenylmaleimide such as imide, or N-substituted alkoxyphenylmaleimide such as N-methoxyphenylmaleimide and N-ethoxyphenylmaleimide), and further halides thereof (for example, N-chlorophenyl) Maleimide), citraconic anhydride, citraconic acid, citraconic acid monoester (eg, methyl citraconic acid, ethyl citraconic acid, propyl citraconic acid, phenyl citraconic acid, etc.), citraconic acid diester (eg, dimethyl citraconic acid, diethyl citraconic acid, citraconic acid) Citraconic anhydride derivatives such as dipropyl acid, diphenyl citraconic acid, etc.), citraconic acid imide or N-substituted derivatives thereof (for example, citraconic acid imide, 2-methyl-N-methylmaleimide, 2-methyl-N-ethylmale) N-substituted alkylmaleimides such as 2-methyl-N-propylmaleimide, 2-methyl-Nn-butylmaleimide, 2-methyl-Nt-butylmaleimide, 2-methyl-N-cyclohexylmaleimide 2-methyl-N-substituted alkylphenylmaleimide such as methyl-N-phenylmaleimide, 2-methyl-N-methylphenylmaleimide, 2-methyl-N-ethylphenylmaleimide, or 2-methyl-N- 2-methyl-N-substituted alkoxyphenylmaleimides such as methoxyphenylmaleimide and 2-methyl-N-ethoxyphenylmaleimide), and further halides thereof (eg 2-methyl-N-chlorophenylmaleimide) Is preferred. Among these, use of maleic anhydride is preferable from the viewpoint of availability, polymerization rate, and ease of molecular weight adjustment. These maleic acids may be used alone or in combination. Maleic acids are neutralized with alkali salts as described above, and the resulting carboxylic acid and carboxylic acid salt form a 1,2-dicarboxylic acid or salt form. This form has a function of capturing heavy metals eluted from the positive electrode.

The content ratio of each structural unit in the copolymer of the present embodiment is preferably such that (A) / (B) is in the range of 1/1 to 1/3 in terms of molar ratio. This is because the advantages of hydrophilicity, water solubility, and affinity for metals and ions as a high molecular weight substance that dissolves in water can be obtained. Particularly, it is desirable that the molar ratio of (A) / (B) is 1/1 or a value close thereto, in which case the unit based on α-olefin, that is, —CH ₂ CR ¹ R ² — A copolymer having a structure in which the units shown and units based on maleic acids are alternately repeated is obtained.

The mixing ratio of α-olefins and maleic acids to obtain the copolymer of the present embodiment varies depending on the composition of the target copolymer, but α-olefin of 1 to 3 times the number of moles of maleic acids. Use of olefin is effective for increasing the reaction rate of maleic acids.

The method for producing the copolymer of the present embodiment is not particularly limited, and for example, the copolymer can be obtained by radical polymerization. In this case, the polymerization catalyst used is an azo catalyst such as azobisisobutyronitrile, 1,1-azobiscyclohexane-1-carbonitrile, or an organic peroxide catalyst such as benzoyl peroxide or dicumyl peroxide. preferable. The amount of the polymerization catalyst used is required to be in the range of 0.1 to 5 mol%, preferably 0.5 to 3 mol% with respect to maleic acids. As a method for adding the polymerization catalyst and the monomer, they may be added all at the beginning of the polymerization, but it is desirable to add them sequentially as the polymerization proceeds.

In the method for producing a copolymer of this embodiment, the molecular weight can be appropriately adjusted mainly depending on the monomer concentration, the amount of catalyst used, and the polymerization temperature. For example, as a substance for reducing the molecular weight, a metal salt of Group I, II or III of the periodic table, a hydroxide, a halide of a Group IV metal, a general formula N≡, HN =, H ₂ N— or H It is also possible to adjust the molecular weight of the copolymer by adding an amine represented by ₄ N-, a nitrogen compound such as ammonium acetate or urea, or a mercaptan during the polymerization or during the polymerization. The polymerization temperature is preferably 40 ° C. to 150 ° C., more preferably 60 ° C. to 120 ° C. If the polymerization temperature is too high, the resulting copolymer tends to be in a block form, and the polymerization pressure may be significantly increased. The polymerization time is usually preferably about 1 to 24 hours, more preferably 2 to 10 hours. The amount of the polymerization solvent used is preferably adjusted so that the concentration of the obtained copolymer is 5 to 40% by weight, more preferably 10 to 30% by weight.

As described above, it is preferable that the copolymer of this embodiment usually has an average molecular weight of 10,000 to 500,000. A more preferred average molecular weight is 15,000 to 450,000. When the average molecular weight of the copolymer of this embodiment is less than 10,000, the crystallinity is high and the adhesive strength between particles may be low. On the other hand, when it exceeds 500,000, the solubility in water or a solvent becomes small, and it may precipitate easily.

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

In this embodiment, the neutralized salt of a copolymer is a neutralized product in which active hydrogen of carbonyl acid generated from maleic acids reacts with a basic substance to form a salt. Is preferred. In the neutralized product of α-olefin-maleic acid copolymer used in the present embodiment, from the viewpoint of binding properties as a binder, the basic substance may be any of a basic substance containing a monovalent metal and ammonia. It is preferred to use either or both. That is, the neutralized salt of the α-olefin-maleic acid copolymer of the present embodiment is a neutralized salt with a basic substance containing a monovalent metal of α-olefin-maleic acid or ammonia of α-olefin-maleic acid. And a neutralized salt thereof or a mixture thereof.

The degree of neutralization is not particularly limited, but when used as a binder, considering the reactivity with the electrolytic solution, it is usually 0.3 to 1 mol per carboxylic acid produced from maleic acids. It is preferably in the range of 1 mole, and more preferably neutralized in the range of 0.4 to 1 mole. With such a neutralization degree, it is possible to adjust the pH of the binder composition of the present embodiment to a predetermined range, and further, there is an advantage that the acidity is low and the electrolytic solution decomposition is suppressed.

In this embodiment, the degree of neutralization can be determined by a method such as titration with a base, an infrared spectrum, or an NMR spectrum. To measure the neutralization point simply and accurately, titration with a base can be performed. preferable. The specific titration method is not particularly limited, but it can be dissolved in water with little impurities such as ion-exchanged water, and a basic substance such as lithium hydroxide, sodium hydroxide, potassium hydroxide, It can be carried out by neutralization. The indicator for the neutralization point is not particularly limited, but an indicator such as phenolphthalein whose pH is indicated by a base can be used.

In the present embodiment, the amount of the basic substance used is not particularly limited and is appropriately selected depending on the purpose of use and the like, but is usually 0.1 per mole of maleic acid units in the maleic acid copolymer. The amount is preferably ˜2 mol. If it is such usage-amount, it will be possible to adjust pH of the binder composition of this embodiment to the predetermined range. The amount of the basic substance containing a monovalent metal is preferably 0.6 to 2.0 mol, more preferably 0.7 to 2. mol per mol of maleic acid unit in the maleic acid copolymer. When the amount is 0 mol, a water-soluble copolymer salt with little alkali residue can be obtained.

The reaction between the α-olefin-maleic acid copolymer and the basic substance can be carried out according to a conventional method, but is carried out in the presence of water, and the neutralized product of the α-olefin-maleic acid copolymer is used as an aqueous solution. The method to obtain is simple and preferable.

Examples of basic substances containing monovalent metals that can be used in the present embodiment include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; alkali metals such as sodium carbonate and potassium carbonate. Carbonates of alkali metals such as sodium acetate and potassium acetate; phosphates of alkali metals such as trisodium phosphate, and the like.

Examples of amines such as ammonia include primary amines such as ammonia, methylamine, ethylamine, butylamine and octylamine, secondary amines such as dimethylamine, diethylamine and dibutylamine, and tertiary amines such as trimethylamine, triethylamine and tributylamine. Is mentioned. Among these, ammonia, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferable as the basic substance. In particular, it is preferable to use ammonia or lithium hydroxide as a binder for a lithium ion secondary battery. The basic substance containing monovalent metal and / or ammonia may be used alone or in combination of two or more. In addition, a neutralized product of an α-olefin-maleic acid copolymer using a basic substance containing an alkali metal hydroxide such as sodium hydroxide as long as the battery performance is not adversely affected. May be prepared.

By including a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid as described above, the non-aqueous electrolyte battery using the binder composition of the present embodiment is electrically Excellent properties.

Next, the binder composition of this embodiment further contains a crosslinking agent. By including a crosslinking agent, adhesiveness and toughness can be imparted to the binder composition. And the binder composition of this embodiment contains polyamines as a crosslinking agent. That is, the binder composition of the present embodiment has a structure in which a neutralized salt of an α-olefin-maleic acid copolymer as described above is crosslinked with a polyamine.

Any polyamine can be used as the cross-linking agent used in the present embodiment without limitation as long as it is electrochemically stable, and examples thereof include polyamines having a molecular weight of 500 or more. .

Specific examples of the high molecular weight polyamines include amino group-containing polymers, and preferred specific examples thereof include polyethyleneimine, polytetramethyleneimine, polyvinylamine, polyallylamine, polydiallylamine, polydimethylallylamine, dicyandiamide-formalin. Examples include condensates and dicyandiamide-alkylene (polyamine) condensates. These may be used alone or in combination. In view of availability and economy, it is preferable to use polyethyleneimine (PEI), polyallylamine, or polydiallylamine.

The molecular weight of these polyamines is not particularly limited, and the average molecular weight is in the range of 500 to 50000, more preferably in the range of 1000 to 30000, and most preferably in the range of 1500 to 25000. The amount of polyamines to be added is not particularly limited, but is usually 0.05 to 30 parts by weight with respect to 100 parts by weight of α-olefin-maleic acid copolymer (solid content). Preferably, it is in the range of 0.3 to 10 parts by weight, most preferably in the range of 0.6 to 5 parts by weight. If the amount of polyamine added is in the range of 0.05 to 30 parts by weight, it is considered that the viscosity of the resulting binder composition can be easily adjusted to a desired range. Moreover, an excessively large addition amount is not preferable because the resistance component increases, and an excessively small addition amount is not preferable because adhesion and toughness cannot be imparted.

In the present embodiment, the polyamines can be added simultaneously with the reaction of the α-olefin-maleic acid copolymer and a basic substance containing a monovalent metal, or the α-olefin-maleic acid copolymer and It can also be added after reacting a basic substance containing a monovalent metal.

Next, in this embodiment, the ring-opening rate of the copolymer represents the hydrolysis rate of the site of maleic anhydride that is polymerized with α-olefins when maleic anhydride is used as the maleic acid. In the copolymer of the present embodiment, a preferable ring opening rate is 60 to 100%, more preferably 70% to 100%, and still more preferably 80 to 100%. If the ring-opening rate is too low, the structural freedom of the copolymer becomes small and the stretchability becomes poor, so that the force for adhering the electrode material particles to be bonded may be small, which is not preferable. Furthermore, there is a possibility that problems such as low affinity for water and poor solubility may occur. The ring-opening rate can be determined, for example, by measuring the hydrogen at the α-position of the maleic acid opened by 1H-NMR with reference to the hydrogen at the α-position of maleic anhydride. The ratio of the carbonyl group derived from the carbonyl group and the ring-opened maleic anhydride can also be determined by IR measurement.

In this embodiment, when the maleic acid is maleic anhydride, the neutralized salt of the copolymer means that the active hydrogen of the carbonyl acid generated by the ring opening of maleic anhydride is a basic substance as described above. It forms a salt by forming a salt. In this case, the degree of neutralization is not particularly limited. However, when used as a binder, considering the reactivity with the electrolytic solution, the degree of neutralization is 0. A range of 2 to 0.8 mol is preferable, and a neutralized range of 0.4 to 0.7 mol is more preferable. Such a neutralization degree has the advantage of low acidity and suppression of electrolyte decomposition. The degree of neutralization of the copolymer when maleic anhydride is used can be measured by the same method as described above.

As described above, in this embodiment, the aqueous solution of the binder composition containing 10% by weight of the neutralized salt has a viscosity at 25 ° C. and a shear rate of 40 s-1 as measured with a Brookfield viscometer. 1800 mPa · s to 15000 mPa · s. Further, the viscosity is more preferably in the range of 2000 mPa · s to 12000 mPa · s. By setting the viscosity in such a range, it is considered that the battery characteristics can be improved without impairing the binding property and toughness of the binder. On the other hand, when the viscosity is less than 1800 mPa, applicability when a slurry described below is produced is poor, and it may not be possible to apply the required thickness, and flexibility may not be imparted. On the other hand, if the viscosity is higher than 12000 mPa · s, handling in production becomes difficult, and further, there is a possibility that uniform mixing cannot be performed when mixing with an active material or a conductive additive.

In this embodiment, the viscosity of the aqueous binder composition solution is adjusted, for example, by adjusting the molecular weight or neutralization degree of the copolymer, the addition amount or molecular weight of polyamines, or by adjusting the neutralization (pH) to be low. The amount can be adjusted to the above range by increasing the amount of carboxylic acid or by adding a thickener, but is not limited thereto.

The viscosity in this embodiment can be measured by, for example, a rotational viscometer method.

Furthermore, it is preferable that the binder composition of this embodiment is a hydrogel.
Examples of water gels that are currently known to form hydrogels include water-soluble polymers such as starch, carrageenan, fiber derivatives, gelatin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, and polyoxyethylene oxide. There is. Hydrogels using these water-soluble polymers are widely used in applications such as a fragrance material, a fireproof material, a heat insulation material, and a cold insulation material.

However, hydrogels using these water-soluble polymers are generally complicated in their production methods. For example, a stepwise temperature adjustment is required (Japanese Patent Laid-Open No. 2013-234280, etc.), a gelation reaction under high temperature is required, or a stable hydrogel is formed unless the temperature is lower than 0 ° C. Production of hydrogel that can be easily gelled is a mainstream production method in which gelation reaction is not possible or it is necessary to promote gelation reaction by strictly adjusting pH of aqueous solution (JP 2009-536940 A, etc.) There are few ways. In addition, when the water content of the hydrogel is high, the gelation reaction is often slow, and the network structure cannot be sufficiently formed in a short time, and the desired performance may not be exhibited.

Furthermore, in this embodiment, a hydrogel obtained from the binder composition using the binder composition described above as a raw material is also included as a preferred embodiment. According to the present embodiment, it is possible to provide a hydrogel that is relatively simple in manufacturing method and can improve secondary battery characteristics.

The hydrogel of this embodiment has a structure in which a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid as described above is crosslinked with a crosslinking agent such as a polyamine. The hydrogel has a transmittance of 40 to 85% in a visible light region (400 to 800 nm) of a 10% by weight aqueous solution. At this time, the 10 wt% aqueous solution means that the solid content of the binder composition forming the hydrogel is 10 wt% as a solid content not containing water.

In the present embodiment, the hydrogel refers to a structure in which a solvent containing water as a main component is taken in and held in a network structure formed by crosslinking a polymer. The amount of the solvent contained in the hydrogel of the present embodiment is not particularly limited as long as the transmittance is in the above range. The solvent taken into the network structure may contain a solvent that dissolves in water or a solvent that is miscible with water to the extent that the effects of the present invention are not affected. The network structure means a network structure stretched in three dimensions by cross-linking an α-olefin-maleic acid copolymer obtained by copolymerizing α-olefins and maleic acids. To do. Thereby, flexibility can be given to the hydrogel.

The hydrogel of the present embodiment preferably has a 10% by weight aqueous solution having a transmittance in the visible light region (400 to 800 nm) of 40 to 85%, more preferably 50 to 75%. More preferably, it is in the range of 45 to 70%.

In the present embodiment, the transmittance specifically refers to the transmittance in the visible light region of 400 to 800 nm when measured with a 10 mm cell using, for example, an ultraviolet / visible spectrophotometer. When the transmittance is higher than 85%, the network structure is not sufficiently formed and a hydrogel cannot be formed. Further, when the transmittance is higher than 85%, the degree of crosslinking is low and the network structure is not developed, so the polymer chain does not spread in the electrode surface, and the particles in the mixed layer cannot be spatially determined. As a result, the flexibility of the electrode is reduced. On the other hand, if the transmittance is lower than 40%, the crosslinking proceeds too much to increase the viscosity and the productivity is extremely deteriorated, which is not preferable. Also, if the transmittance is too low, the network structure will develop too much, and it will not be able to be sufficiently disintegrated with the solid content at the time of slurry production, and the binder (hydrogel as binder) will not disperse.・ Deterioration of flexibility occurs, causing deterioration of battery characteristics.

That is, in the hydrogel of the present embodiment, the transmittance in the visible light region (400 to 800 nm) of a 10% by weight aqueous solution is in the range of 40 to 85%, which means that among α-olefin-maleic acid copolymers. It means that the Japanese salt has an appropriate network structure by being appropriately crosslinked. By having such an appropriate network structure, there is an advantage that it is not necessary to use a large amount of a crosslinking agent which is usually required. In general, when a large amount of a crosslinking agent is added, problems such as an increase in swellability due to the network structure and an increase in resistance due to the crosslinking agent may occur, but it is considered that these disadvantages do not occur in this embodiment.

In this embodiment, the permeability of the hydrogel refers to the type of crosslinking agent (for example, polyamines) described later, the molecular weight, the added amount, and the neutralization degree of the neutralized salt of the α-olefin-maleic acid copolymer. It can be adjusted by means such as adjustment.

The method for obtaining the hydrogel of the present embodiment is not particularly limited. For example, a neutralized salt of an α-olefin-maleic acid copolymer as described above is mixed with a crosslinking agent as described above. After the dropwise addition, it can be produced by heating and stirring at about 60 to 90 ° C. for 1 to 8 hours. That is, it can be obtained by using the binder composition of the present embodiment as a raw material and, for example, heating and stirring it as described above.

The hydrogel of the present embodiment defines the transmittance when the solid content is 10% by weight aqueous solution (that is, when the amount of water is 90% by weight), but is included in the hydrogel of the present embodiment. The amount of water is not limited to 90% by weight as long as the effect of the present invention is exhibited. The amount of water contained in the hydrogel is preferably 3% to 20% by weight, more preferably 5% to 15% by weight.

The binder composition that is the raw material of the hydrogel of the present embodiment preferably has the same range viscosity as the above-described binder composition of the present embodiment as the viscosity before heating for producing the hydrogel, and further It is desirable that the viscosity of the 10% by weight aqueous solution before heating at 25 ° C. and at a shear rate of 40 s-1 is 2300 mPa · s to 15000 mPa · s. When the viscosity is too low, the network structure is not sufficiently formed and a hydrogel cannot be formed. If the viscosity is too high, the slurry cannot be sufficiently kneaded, resulting in an unstable slurry as well as difficult electrode formation, leading to an increase in electrical resistance. The viscosity in this embodiment can be measured by, for example, a rotational viscometer method.

The binder composition for nonaqueous electrolyte battery electrodes is often used for production of a slurry composition that continues in a state of containing water. Under the present circumstances, in the said binder composition for nonaqueous electrolyte battery electrodes, you may dilute with water from a viewpoint on viscosity adjustment and manufacture, and you may crush hydrogel. In addition, the hydrogel of this embodiment may be used by further diluting with a solvent such as water in the subsequent production of the slurry composition, or the hydrogel itself may be crushed for viscosity adjustment.

Further, the method for diluting or crushing the crosslinked binder composition or hydrogel in the present embodiment is not particularly limited as long as a uniform aqueous binder composition solution can be obtained. Examples thereof include a method using a rotation / revolution mixer, a planetary mixer, a planetary ball mill, a bead mill, and the like.

The binder composition for a nonaqueous electrolyte battery electrode of the present embodiment is usually a slurry composition for a nonaqueous electrolyte battery electrode (hereinafter simply referred to as a slurry) which further contains an active material and water in addition to the binder composition described above. It is preferably used as a composition). Moreover, it is preferable that the hydrogel of this embodiment is used as a slurry composition for non-aqueous electrolyte battery electrodes further containing an active material. The slurry composition containing the hydrogel may be additionally added with water when it is produced.

Further, in the present embodiment, the nonaqueous electrolyte battery negative electrode is characterized in that a current collector is bound with a mixed layer containing at least the binder composition (or hydrogel) of the present embodiment and an active material. This negative electrode can be formed by applying the slurry composition described above to a current collector and then removing the solvent by a method such as drying. If necessary, a thickener, a conductive aid and the like can be added to the mixed layer.

In the slurry composition for a non-aqueous electrolyte battery electrode, the amount of neutralized salt of α-olefin-maleic acid copolymer used relative to 100 parts by weight of the active material is usually 0.4 to 15 parts by weight. The amount is preferably 0.6 to 10 parts by weight, more preferably 1 to 8 parts by weight. If the amount of the copolymer is too small, the viscosity of the slurry may be too low and the thickness of the mixed layer may be reduced. Conversely, if the amount of the copolymer is excessive, the discharge capacity may be reduced.

On the other hand, the amount of water in the slurry composition is usually preferably 40 to 150 parts by weight, more preferably 70 to 130 parts by weight with respect to 100 parts by weight of the active material.

As the solvent in the negative electrode slurry composition of the present embodiment, in addition to the above water, for example, alcohols such as methanol, ethanol, propanol and 2-propanol, cyclic ethers such as tetrahydrofuran and 1,4-dioxane, N, Amides such as N-dimethylformamide and N, N-dimethylacetamide, cyclic amides such as N-methylpyrrolidone and N-ethylpyrrolidone, and sulfoxides such as dimethylsulfoxide can also be used. In these, use of water is preferable from a viewpoint of safety.

Further, in addition to water as the solvent for the negative electrode slurry composition of the present embodiment, the following organic solvents may be used in combination within a range of preferably 20% by weight or less of the total solvent. Such an organic solvent preferably has a boiling point at normal pressure of 100 ° C. or higher and 300 ° C. or lower, for example, hydrocarbons such as n-dodecane; alcohols such as 2-ethyl-1-hexanol and 1-nonanol. Esters such as γ-butyrolactone and methyl lactate; amides such as N-methylpyrrolidone, N, N-dimethylacetamide and dimethylformamide; and organic dispersion media such as sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane.

When the slurry composition of this embodiment is used for a negative electrode, examples of the active material (negative electrode active material) added to the negative electrode slurry composition include amorphous carbon, graphite, natural graphite, and mesocarbon microbeads (MCMB). ), Carbonaceous materials such as pitch-based carbon fibers; conductive polymers such as polyacene; composite metal oxides represented by SiOx, SnOx, LiTiOx, other metal oxides, lithium metals such as lithium metals and lithium alloys A metal compound such as TiS ₂ and LiTiS ₂ is exemplified.

In this embodiment, a thickener can be further added to the slurry composition as necessary. The thickener that can be added is not particularly limited, and various alcohols, in particular, polyvinyl alcohol and modified products thereof, celluloses, starches, and other polysaccharides can be used.

Further, examples of the conductive auxiliary compounded in the slurry composition as necessary include metal powder, conductive polymer, acetylene black, and the like. The amount of the conductive aid used is usually preferably 0.1 to 10 parts by weight, more preferably 0.8 to 7 parts by weight with respect to 100 parts by weight of the negative electrode active material.

The current collector used for the nonaqueous electrolyte battery negative electrode 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, gold Metal materials such as platinum can be used. One of these may be used alone, or two or more of these may be used in combination at any ratio.

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

The method for applying the slurry to the current collector is not particularly limited. Examples thereof include a doctor blade method, a dip 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 to be applied is not particularly limited, but the thickness of the mixed layer containing the active material, conductive additive, binder and thickener formed after removing the solvent or dispersion medium by a method such as drying is preferably 0.005 to An amount of 5 mm, more preferably 0.01 to 2 mm is common.

The method for drying a solvent such as water contained in the slurry composition is not particularly limited, and examples thereof include aeration drying with hot air, hot air, and low-humidity air; vacuum drying; . The drying conditions are preferably adjusted so that the solvent can be removed as soon as possible while the active material layer is cracked by stress concentration or the active material layer does not peel from the current collector. Furthermore, in order to increase the density of the active material of the electrode, it is effective to press the current collector after drying. Examples of the pressing method include a die press and a roll press.

Furthermore, the present invention also includes a non-aqueous electrolyte battery having the negative electrode. The nonaqueous electrolyte battery usually includes the negative electrode, the positive electrode, and an electrolytic solution.

In this embodiment, the positive electrode normally used for nonaqueous electrolyte batteries, such as a lithium ion secondary battery, is especially used for a positive electrode without a restriction | limiting. For example, as the positive electrode active material, TiS ₂ , TiS ₃ , amorphous MoS ₃ , Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O Transition metal oxides such as ₁₃ and lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiMn ₂ O ₄ are used. Further, the positive electrode active material is made of a conductive additive similar to that of the negative electrode, and a binder such as SBR, NBR, acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinylidene fluoride, and the boiling point at 100 ° C. in water or the above normal pressure. The positive electrode slurry prepared by mixing in a solvent of 300 ° C. or lower can be applied to a positive electrode current collector such as aluminum and the solvent can be dried to obtain a positive electrode.

In the nonaqueous electrolyte battery of this embodiment, an electrolytic solution in which an electrolyte is dissolved in a solvent can be used. The electrolyte solution may be liquid or gel as long as it is used for a non-aqueous electrolyte battery such as a normal lithium ion secondary battery, and functions as a battery depending on the type of the negative electrode active material and the positive electrode active material. What is necessary is just to select suitably. Specific electrolytes, for example, also known lithium salt is any conventionally _{_{_{available, LiClO 4, LiBF 6, LiPF}}} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10 _{_{, LiAlC l4, 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 And lower aliphatic lithium carboxylates.

The solvent for dissolving such an electrolyte (electrolytic solution solvent) is not particularly limited. Specific examples include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, and diethyl carbonate; lactones such as γ-butyllactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, and 2-ethoxyethane. Ethers such as tetrahydrofuran, 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane, 4-methyl-1,3-dioxolane; nitrogen-containing compounds such as acetonitrile and nitromethane; formic acid Organic acid esters such as methyl, methyl acetate, ethyl acetate, butyl acetate, methyl propionate and ethyl propionate; inorganic acid esters such as triethyl phosphate, dimethyl carbonate and diethyl carbonate Tergories; diglymes; triglymes; sulfolanes; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propane sultone, 1,4-butane sultone, naphtha sultone, and the like. Alternatively, two or more kinds can be mixed and used. When a gel electrolyte is used, a nitrile polymer, an acrylic polymer, a fluorine polymer, an alkylene oxide polymer, or the like can be added as a gelling agent.

The method for producing the non-aqueous electrolyte battery of the present embodiment is not particularly limited, and for example, the following production method is exemplified. That is, the negative electrode and the positive electrode are overlapped with each other via a separator such as a polypropylene porous membrane, wound or folded according to the shape of the battery, put into a battery container, injected with an electrolyte, and sealed. The shape of the battery may be any known coin type, button type, sheet type, cylindrical type, square type, flat type, and the like.

The nonaqueous electrolyte battery of the present embodiment is a battery that achieves both improved adhesion and improved battery characteristics, and is useful for various applications. For example, it is very useful as a battery for portable terminals that require miniaturization (light weight, thinning, etc.) and high performance (high output, high capacity, low resistance, long life, etc.). It is.

This specification discloses various modes of technology as described above, and the main technologies are summarized below.

With such a configuration, it is considered that the battery characteristics can be improved without impairing the binding property between the active materials and the collector electrode and the toughness as the electrode.

Further, a hydrogel having a transmittance of 40 to 85% in a visible light region (400 to 800 nm) of a 10% by weight aqueous solution obtained from the binder composition is preferable.

In the present embodiment, a three-dimensional network structure is developed with the above-described configuration, and a transparent hydrogel can be provided. By using this, battery characteristics (low resistance) and functionality ( A hydrogel excellent in flexibility) can also be provided. Further, the hydrogel of the present invention has an advantage that it can be obtained by a relatively simple production method.

Further, a slurry composition for a nonaqueous electrolyte battery electrode according to still another aspect of the present invention is characterized by containing the binder composition and an active material.

A slurry composition for a nonaqueous electrolyte battery electrode according to still another aspect of the present invention is characterized by containing the hydrogel and an active material.

A non-aqueous electrolyte battery negative electrode according to still another aspect of the present invention is formed by binding a current collector to a mixed layer containing at least the binder composition for a non-aqueous electrolyte battery electrode and an active material. Features.

A nonaqueous electrolyte battery negative electrode according to still another aspect of the present invention is characterized in that a mixed layer containing at least the hydrogel and an active material is bound to a current collector.

Also, a nonaqueous electrolyte battery according to still another aspect of the present invention is characterized by having the above nonaqueous electrolyte battery negative electrode.

Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

<Test Example 1>
Example 1
<Preparation of binder composition>
Using a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring-opening rate 96%), a 10% by weight aqueous solution was prepared and used in the following tests. . The pH is adjusted by adjusting the degree of neutralization of the copolymer resin. Specifically, 1 equivalent (0.16 mol) of lithium hydroxide is added to the maleic acid unit in the maleic acid copolymer. Went by.

5 g of a 10% by weight aqueous solution of polyethyleneimine (PEI, average molecular weight 10,000, manufactured by Nippon Shokubai Co., Ltd.) as a crosslinking agent was added dropwise to 500 g of the 10% by weight aqueous solution of the resin at 0.5 ml / min, and the mixture was stirred at 60 ° C. for 7 hours. did. Then, it cooled to room temperature and used as binder aqueous solution containing a binder composition.

<Measurement of viscosity of binder composition for negative electrode>
Using a Brookfield viscometer (DV-I PRIME Brookfield), the viscosity of the 10% by weight aqueous solution (binder aqueous solution) of the binder composition obtained above was measured at 25 ° C. The viscosity results when the shear rate ^{40 s -1} are shown in Table 1 below.

<Dilution of binder liquid>
An equivalent amount of water was added to the 10% by weight of the binder solution (binder aqueous solution) prepared above, and diluted using a planetary stirrer (ARE-250, manufactured by Sinky) to obtain a 5% by weight binder composition.

<Preparation of slurry for negative electrode>
The slurry for the electrode was prepared by using 6.452 parts by weight of a 5% by weight aqueous solution of the binder composition for the negative electrode as a solid content with respect to 100 parts by weight of natural graphite (DMGS, manufactured by BYD) as the negative electrode active material, and a conductive auxiliary agent ( Super-P (made by Timcal Co., Ltd.) as a conductivity imparting agent) 1.075 parts by weight as a solid content is put into a special container and kneaded using a planetary stirrer (ARE-250, made by Shinky) for electrode coating. A slurry was prepared. The composition ratio of the active material and the binder in the slurry is, as a solid content, graphite powder: conducting aid: binder composition = 100: 1.075: 6.452.

<Preparation of negative electrode for battery>
The obtained slurry was coated on a current collector copper foil (CST8G, manufactured by Fukuda Metal Foil Co., Ltd.) using a bar coater (T101, manufactured by Matsuo Sangyo), and then primary dried at room temperature (24.5 ° C). Then, the rolling process was performed using the roll press (made by Hosen). Then, after punching out as a battery electrode (φ14 mm), a coin battery electrode (battery negative electrode) was produced by secondary drying under reduced pressure conditions at 140 ° C. for 3 hours.

<Preparation of peel strength and toughness test electrode>
The obtained slurry was coated on a current collector copper foil (CST8G, manufactured by Fukuda Metal Foil Co., Ltd.) using a bar coater (T101, manufactured by Matsuo Sangyo), and then primary dried at room temperature (24.5 ° C). Then, it tested using the electrode (film thickness of about 50 micrometers) which performed the rolling process using the roll press (made by Hosen).

<Electrode toughness test>
Evaluation of electrode toughness is based on JIS K5600-5-1 (General coating test method-Part 5: Mechanical properties of coating film-Section 1: Bending resistance (cylindrical mandrel method)) Used. When the electrode crack was visually confirmed, no crack was observed even at the minimum diameter of 2 mm in this test. Therefore, 1.5 mm, 1.0 mm, 0.8 mm, and 0.5 mm SUS bars (manufactured by SUS304Wire Nilaco) were prepared, and an electrode winding test was performed. Table 1 below shows the results of the minimum SUS diameter in which no cracks occurred.

<Measurement of peel strength of electrode>
The strength when the electrode was peeled off from the copper foil as the collecting electrode was measured. The peel strength was measured at 180 ° peel strength using a 50N load cell (manufactured by Imada Co., Ltd.). The slurry-coated surface of the battery-coated electrode obtained above and a stainless steel plate were bonded together using a double-sided tape (double-faced tape made by Nichiban), and the 180 ° peel strength (peel width 10 mm, peel rate 100 mm / min) was measured. did. The results are shown in Table 1 below.

<Production of battery>
The battery coated electrode (battery negative electrode) obtained above was transferred to a glove box (manufactured by Miwa Seisakusho) under an argon gas atmosphere. A metal lithium foil (thickness 0.2 mm, φ16 mm) was used for the positive electrode. In addition, a polypropylene system (Celgard # 2400, manufactured by Polypore) is used as a separator, and the electrolyte is ethylene carbonate (EC) of lithium hexafluorophosphate (LiPF ₆ ) and ethylene carbonate (EMC) with vinylene carbonate (VC). ) added was mixed solvent system _{(1M-LiPF 6, EC /} EMC = 3 / 7vol%, were injected with VC2 wt%) to prepare a coin battery (2032 type).

<Evaluation method: charge / discharge characteristic test>
The produced coin battery was subjected to a charge / discharge test using a commercially available charge / discharge tester (TOSCAT3100, manufactured by Toyo System). The coin battery is placed in a constant temperature bath at 25 ° C., and charging is performed with a constant current of 0.1 C (about 0.5 mA / cm ² ) with respect to the amount of active material until the voltage reaches 0 V with respect to the lithium potential. On the other hand, the constant voltage charge of 0V was implemented to the electric current of 0.02 mA. The capacity at this time was defined as a charging capacity (mAh / g). Next, a constant current discharge of 0.1 C (about 0.5 mA / cm ² ) was performed up to 1.5 V with respect to the lithium potential, and the capacity at this time was defined as a discharge capacity (mAh / g). The difference between the initial discharge capacity and the charge capacity was taken as the irreversible capacity, and the percentage of the discharge capacity / charge capacity was taken as the charge / discharge efficiency. As the direct current resistance of the coin battery, a resistance value after being charged once (fully charged state) was adopted. The results are shown in Table 1 below.

(Example 2)
Using the resin and the crosslinking agent (PEI) used in Example 1, the same method as in Example 1 so that 10% by weight aqueous solution of resin: 10% by weight aqueous solution of PEI = 99.7: 0.3 The binder composition was prepared by The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below.

The electrode slurry preparation is 6.452 parts by weight of a 10% by weight aqueous solution of the binder composition for the negative electrode as a solid content with respect to 100 parts by weight of natural graphite (DMGS, manufactured by BYD) as the negative electrode active material, and a conductive additive ( Super-P (made by Timcal Co., Ltd.) as a conductivity imparting agent) 1.075 parts by weight as a solid content is put into a special container and kneaded using a planetary stirrer (ARE-250, made by Shinky) for electrode coating. A slurry (slurry for negative electrode) was prepared. The composition ratio of the active material and the binder in the slurry is, as a solid content, graphite powder: conducting aid: binder composition = 100: 1.075: 6.452.

A coated negative electrode (a negative electrode for a battery) was prepared in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. In addition, a toughness test and a peel strength measurement were performed using a coated electrode (peel strength, electrode for toughness test). The results are shown in Table 1 below.

(Example 3)
Using the resin and PEI used in Example 1, a binder composition was prepared in the same manner as in Example 1 so that the resin was 10% by weight aqueous solution: PEI 10% by weight aqueous solution = 98: 2. It was. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. Thereafter, the binder composition was diluted by the same method as in Example 1 to obtain a 5% by weight binder composition. Next, a nonaqueous electrolyte battery electrode slurry (negative electrode slurry) was prepared in the same manner as in Example 1 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

Example 4
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.7, ring opening rate 97%) was prepared, and lithium hydroxide was co-polymerized with maleic acids. The pH was adjusted by adding 1.4 equivalents to the maleic acid unit in the coalescence.

Using the above resin and the PEI used in Example 1, the binder composition was prepared in the same manner as in Example 1 so that the resin 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 99: 1. went. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. A slurry for a nonaqueous electrolyte battery electrode was produced in the same manner as in Example 2 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Example 5)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.4, ring opening rate 92%) was prepared, and lithium hydroxide was co-polymerized with maleic acids. The pH was adjusted by adding 0.8 equivalent to the maleic acid unit in the coalescence.

Using the above resin and the PEI used in Example 1, the binder composition was prepared in the same manner as in Example 1 so that the resin 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 99: 1. went. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. Thereafter, the binder composition was diluted by the same method as in Example 1 to obtain a 5% by weight binder composition. Next, a slurry for a nonaqueous electrolyte battery electrode was produced by the same method as in Example 1 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Comparative Example 1)
A 10% by weight aqueous solution of the resin used in Example 1 was prepared and used as a negative electrode binder composition without adding PEI. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. A slurry for a nonaqueous electrolyte battery electrode was produced in the same manner as in Example 2 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Comparative Example 2)
Using the resin and crosslinking agent (PEI) used in Example 1, the same method as in Example 1 so that the 10% by weight aqueous resin solution: 10% by weight aqueous PEI solution = 99.97: 0.03 The binder composition was prepared by The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. Thereafter, a slurry for a nonaqueous electrolyte battery electrode was produced in the same manner as in Example 2 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Comparative Example 3)
Using the resin and PEI used in Example 1, a binder composition was prepared in the same manner as in Example 1 so that the resin was 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 90: 10. It was. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. Thereafter, the binder composition was diluted by the same method as in Example 1 to obtain a 5% by weight binder composition. Next, a slurry for a nonaqueous electrolyte battery electrode was produced by the same method as in Example 1 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Comparative Example 4)
Using the resin and polyallylamine (molecular weight 3000) used in Example 1, a binder composition was prepared in the same manner as in Example 1 so that the resin 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 99: 1. The product was prepared. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 1 below. Thereafter, the binder composition was diluted by the same method as in Example 1 to obtain a 5% by weight binder composition. Next, a slurry for a nonaqueous electrolyte battery electrode was produced by the same method as in Example 1 above. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the toughness test and peel strength measurement were performed using the coated electrode. The results are shown in Table 1 below.

(Discussion)
In Examples 1 to 5, the crosslinking agent (polyamines) is contained in the negative electrode binder composition, and the viscosity at 25 ° C. and the shear rate of 40 s ⁻¹ of the aqueous solution containing 10% by weight is 1800 mPa · s to 12000 mPa · s. Improvement of toughness and adhesiveness was observed due to the crosslinking effect caused by the formation of acid and salt. In addition, since the viscosity is increased by adding a crosslinking agent, it is possible to prepare a slurry without using a thickener. As is apparent from Table 1, it was shown that the addition of a cross-linking agent does not significantly affect the battery characteristics and realizes low resistance. In contrast, Comparative Example 1 that does not contain polyamines and Comparative Examples 2 to 4 in which the viscosity is outside the scope of the present invention even when polyamines are added resulted in low toughness and adhesion. .

<Test Example 2>
(Example 6)
<Manufacture of hydrogel>
A water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring-opening rate 96%) was used, and a 10% by weight aqueous solution was prepared and used in the following tests. .

A 10% by weight aqueous solution of polyethyleneimine (PEI, average molecular weight 10,000, manufactured by Nippon Shokubai Co., Ltd.) as a cross-linking agent was added to the 10% by weight aqueous resin solution. Then, it was dropped at 2.0 ml / h while stirring with a hand mixer (WARING STAND MIXER, manufactured by WARING). Thereafter, the mixture was heated and stirred at 90 ° C. for 2 hours to obtain a hydrogel.

<Measurement of transmittance>
The transmittance of the obtained hydrogel was measured with an ultraviolet / visible spectrophotometer (UV-2600 series, Shimadzu Corporation) using a 10 mm cell. Table 2 shows the results of the lowest transmittance values in the visible light region between 400 nm and 800 nm.

<Measurement of viscosity of hydrogel>
Using a Brookfield viscometer (DV-I PRIME Brookfield), the viscosity of a 10% by weight aqueous solution of hydrogel after addition of polyethyleneimine (before heating) was measured at 25 ° C. The viscosity results at a shear rate of 40 s ^-1 are shown in Table 2 below.

<Dilution of hydrogel>
An equivalent amount of water was added to 10% by weight of the hydrogel prepared above, and 5% by weight of a negative electrode binder liquid was obtained using a hand mixer (WARING STAND MIXER, manufactured by WARING).

<Preparation of slurry for negative electrode>
A slurry for electrode coating was prepared in the same manner as in Test Example 1 (Example 1) except that a 5 wt% aqueous solution of hydrogel was used instead of the 5 wt% aqueous solution of the negative electrode binder composition. The composition ratio of the active material and the hydrogel in the slurry is, as a solid content, graphite powder: conductive auxiliary agent: hydrogel (weight as a binder composition excluding moisture) = 100: 1.075: 6.452.

<Preparation of negative electrode for battery>
A coin battery electrode (battery negative electrode) was prepared in the same manner as in Test Example 1 (Example 1).

<Production of electrode for flexibility (toughness) test>
A test was performed using an electrode produced in the same manner as in <Preparation of peel strength and toughness test electrode> in Test Example 1 (Example 1).

<Electrode flexibility (toughness) test>
The flexibility (toughness) of the electrode was evaluated in the same manner as the electrode toughness test of Test Example 1 (Example 1). The results are shown in Table 2 below.

<Production of battery>
A coin battery (2032 type) was produced in the same manner as the electrode toughness test of Test Example 1 (Example 1).

<Evaluation method: charge / discharge characteristic test>
With the produced coin battery, the same charge / discharge test as in Test Example 1 was performed. The results are shown in Table 2 below.

(Example 7)
Using the resin and the crosslinking agent (PEI) used in Example 6, a hydrogel was prepared by the same method as in Example 6 so that the resin 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 99: 1, Transmittance and viscosity were measured. The results are shown in Table 2 below. Then, the hydrogel dilution and the slurry for nonaqueous electrolyte batteries (slurry for negative electrodes) were produced by the same method as Example 6. Further, a coated negative electrode (battery negative electrode) was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. In addition, a flexibility test was performed using a coated electrode (peel strength, toughness test electrode). The results are shown in Table 2 below.

(Example 8)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.7, ring opening rate 97%) was prepared.

Using the above resin aqueous solution and the PEI used in Example 6, a 10% by weight aqueous resin: 10% by weight aqueous PEI solution = 99: 1 was prepared, and a hydrogel was prepared by the same method as in Example 6, and the transmittance And the viscosity was measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coating electrode. The results are shown in Table 2 below.

Example 9
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.4, ring opening rate 92%) was prepared.

Using the resin aqueous solution and PEI used in Example 6, a hydrogel was prepared by the same method as in Example 6 so that the resin 10% by weight aqueous solution: PEI 10% by weight aqueous solution = 99: 1. The viscosity was measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coating electrode. The results are shown in Table 2 below.

(Example 10)
Using the resin and the cross-linking agent (polyallylamine, molecular weight 3,000) used in Example 8, the resin 10% by weight aqueous solution: PEI 10% by weight aqueous solution = 99.34: 0.66 A hydrogel was prepared by the same method, and the transmittance and viscosity were measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coating electrode. The results are shown in Table 2 below.

(Example 11)
As a negative electrode binder composition, a 10% by weight aqueous solution of a water-soluble lithium-modified methyl vinyl ether-maleic anhydride copolymer resin (average molecular weight 630,000, neutralization degree 0.5, ring opening rate 96%) was prepared.

Using the resin and PEI used in Example 6, a hydrogel was prepared by the same method as in Example 6 so that the resin 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 95: 5, and the transmittance and The viscosity was measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Example 12)
A 10% by weight aqueous solution of a water-soluble lithium-modified ethylene-maleic anhydride copolymer resin (average molecular weight 350,000, neutralization degree 0.5, ring opening rate 96%) was prepared.

Using the above resin aqueous solution and the PEI used in Example 6, a hydrogel was prepared by the same method as in Example 6 so that the resin 10% by weight aqueous solution: PEI 10% by weight aqueous solution = 95: 5, and the transmittance And the viscosity was measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 5)
Using the resin and the crosslinking agent (PEI) used in Example 6, a hydrogel was prepared by the same method as in Example 6 so that the resin was 10 wt% aqueous solution: PEI 10 wt% aqueous solution = 90: 10, Transmittance and viscosity were measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 6)
Using the resin and crosslinking agent (PEI, molecular weight 600) used in Example 7, a hydrogel was prepared by the same method as in Example 7, and the transmittance and viscosity were measured. The results are shown in Table 2 below. Thereafter, a hydrogel dilution and a nonaqueous electrolyte battery slurry were prepared in the same manner as in Example 6. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 7)
The results of measuring the transmittance and viscosity of a 10% by weight aqueous resin solution (no additive) used in Example 6 are shown in Table 2 below. Thereafter, a slurry for a non-aqueous electrolyte battery was produced in the same manner as in Example 6 using the 10 wt% aqueous solution as a binder solution. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 8)
Table 2 below shows the results of measuring the transmittance and viscosity of a 10% by weight aqueous solution (without additives) of the resin used in Example 10. Then, the slurry for nonaqueous electrolyte batteries was produced by the method similar to the said comparative example 7. Subsequently, the coating negative electrode was produced by the method similar to the said Example 6, the coin battery was obtained, and the charge / discharge characteristic test was done. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 9)
The results of measuring the viscosity and transmittance of a 10% by weight aqueous solution of the resin used in Example 11 (without additives) are shown in Table 2 below. Then, the slurry for nonaqueous electrolyte batteries was produced by the method similar to the said comparative example 7. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Comparative Example 10)
Similar to Comparative Example 7 above, using an aqueous SBR emulsion aqueous solution (TRD2001, 48.3% by weight), which is a conventional aqueous negative electrode binder composition, and CMC-Na (cellogen BSH-6, 10% by weight) as a thickener. A slurry for a nonaqueous electrolyte battery was prepared by the method. The composition ratio between the active material and the binder in the slurry was, as a solid content, graphite powder: conductive aid: SBR: CMC-Na = 100: 1.053: 3.158: 1.053. Further, a coated negative electrode was prepared by the same method as in Example 6 to obtain a coin battery, and a charge / discharge characteristic test was performed. Moreover, the flexibility test was done using the coated electrode. The results are shown in Table 2 below.

(Discussion)
It was shown that an electrode with higher flexibility (toughness) can be produced by using a hydrogel having a predetermined transmittance according to the present invention. Further, according to the present invention, even when a crosslinking agent for hydrogelation is added, the conventional binder shown in Comparative Example 10 shows low resistance equivalent to that of the non-added products shown in Comparative Examples 7 to 9. It was found to be lower than the SBR-CMC system, which contributes to improving battery characteristics. On the other hand, the hydrogels of Comparative Examples 6 to 9 having a high transmittance could not provide sufficient flexibility. Further, in Comparative Example 5 in which the addition amount of the cross-linking agent was high and the transmittance was low, the viscosity was too high, and crushing at the time of slurry preparation could not be sufficiently performed, resulting in a battery having high resistance. Furthermore, in Comparative Example 6 in which the molecular weight of the polyamines was low, the degree of crosslinking was not sufficient, so the viscosity was low, and sufficient flexibility could not be provided.

This application is based on Japanese Patent Application No. 2016-231352 filed on November 29, 2016 and Japanese Patent Application No. 2016-242847 filed on December 15, 2016. The contents thereof are included in the present application.

In order to express the present invention, the present invention has been described appropriately and sufficiently through the embodiments with reference to specific examples and the like. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not limited to the scope of the claims. To be construed as inclusive.

The present invention has wide industrial applicability in the technical field related to non-aqueous electrolyte batteries such as lithium ion secondary batteries.

Claims

A binder composition for a non-aqueous electrolyte battery electrode, comprising a structure in which a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid is crosslinked with a polyamine. A binder composition characterized in that an aqueous solution containing 10% by weight of the composition has a viscosity of 1800 mPa · s to 15000 mPa · s at 25 ° C. and a shear rate of 40 s −1 .
A hydrogel obtained from the binder composition according to claim 1, having a transmittance of 40 to 85% in a visible light region (400 to 800 nm) of a 10% by weight aqueous solution.
A slurry composition for a nonaqueous electrolyte battery electrode, comprising the binder composition according to claim 1 and an active material.
A slurry composition for a nonaqueous electrolyte battery electrode, comprising the hydrogel according to claim 2 and an active material.
A negative electrode for a non-aqueous electrolyte battery, wherein a mixed layer containing the binder composition according to claim 1 and an active material is bound to a current collector.
A negative electrode for a non-aqueous electrolyte battery, wherein the mixed layer containing the hydrogel according to claim 2 and an active material is bound to a current collector.
A nonaqueous electrolyte battery comprising the negative electrode for a nonaqueous electrolyte battery according to claim 5.