JP2018125094A - Binder composition for nonaqueous electrolyte battery electrode, slurry composition for nonaqueous electrolyte battery electrode arranged by use thereof, nonaqueous electrolyte battery electrode, and nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder composition which never mars a function as a nonaqueous electrolyte battery electrode binder, i.e. a binding ability among active materials and with a collector electrode, and the toughness as an electrode, and which is superior in battery characteristics in a nonaqueous electrolyte battery.SOLUTION: A binder composition for a nonaqueous electrolyte battery electrode, comprises hydrogel consisting of a water-soluble polymer. In regard to the relaxation time of water according to pulse NMR when the binder composition has a solid content concentration 5.5 wt.%, the confined-water relaxation time τis 20 msec or longer, and the free-water relaxation time τis 300 msec or longer.SELECTED DRAWING: None

Description

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

  In recent years, mobile terminals such as mobile phones, notebook computers, and 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.

  Up to now, 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 in order 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 the nonaqueous electrolyte battery, since the battery capacity is affected by the amount of the active material, it is effective to suppress the amount of the binder and the 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.

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

  The present invention has been made in view of the above-mentioned problems, and the battery characteristics in the nonaqueous electrolyte battery are obtained without impairing the function as the binder, that is, the binding property between the active materials and the collector electrode and the toughness as the electrode. The purpose is to improve.

  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 having the following constitution, and further studies are made based on this finding. The present invention was completed by overlapping.

That is, the binder composition for a nonaqueous electrolyte battery according to one aspect of the present invention (hereinafter also simply referred to as a binder composition) is a composition containing a hydrogel composed of a water-soluble polymer, and has a solid content concentration of 5.5. In the case of weight%, the restricted water relaxation time τ ₂ in the relaxation time of water by pulse NMR is 20 milliseconds or more, and the free water relaxation time τ ₃ is 300 milliseconds or more. Moreover, it is preferable that the hydrogel which consists of this water-soluble polymer contains the neutralized salt and polyamine of the alpha-olefin-maleic acid copolymer which alpha-olefins and maleic acid copolymerized.

  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.

  Moreover, the binder aqueous solution for non-aqueous electrolyte batteries which concerns on the other situation of this invention consists of the said binder composition and water, It is characterized by the above-mentioned.

  A slurry composition for a non-aqueous electrolyte battery according to still another aspect of the present invention includes the binder composition, an active material, and a solvent.

  As a nonaqueous electrolyte battery electrode according to still another aspect of the present invention, a current collector is formed by binding a mixed layer containing at least the binder composition for a nonaqueous electrolyte battery and an active material. And

  A nonaqueous electrolyte battery according to still another aspect of the present invention includes the above nonaqueous electrolyte battery negative electrode, a positive electrode, and an electrolytic solution.

  ADVANTAGE OF THE INVENTION According to this invention, the binder composition for nonaqueous electrolyte batteries provided with binding property and toughness can be obtained, and also the improvement of the battery characteristic of a nonaqueous electrolyte battery can be implement | achieved using it.

  Hereinafter, although embodiment of this invention is described in detail, this invention is not limited to these.

The binder composition for a non-aqueous electrolyte battery according to this embodiment is a composition containing a hydrogel composed of a water-soluble polymer, and when the solid content concentration is 5.5% by weight, the relaxation time of water by pulse NMR is The restricted water relaxation time τ ₂ is 20 milliseconds or more, and the free water relaxation time τ ₃ is 300 milliseconds or more.

  In the present embodiment, the hydrogel refers to a state in which the binder resin (polymer) has a three-dimensional network structure and is a swollen body containing water inside the network structure. By including such a hydrogel, binding properties and toughness can be imparted to the binder composition.

  Since the binder composition of the present embodiment is a hydrogel, water is added at the time of use, and the hydrogel is crushed and dispersed in a liquid. The method for crushing the hydrogel is not particularly limited, but mixers such as planetary mixers and static mixers, stirrers such as mechanical stirrers and magnetic stirrers, and pulverizers such as ball mills and planetary mills are used. can do.

  The obtained hydrogel pulverized dispersion is composed of a hydrogel that has been reduced in size by pulverization and free water as a solvent. Free water is composed of water present in the hydrogel released by crushing and water added during crushing. When this hydrogel pulverized product dispersion was measured by pulse NMR, it was found that the constrained water present in the atomized hydrogel, the free water composed of the water present in the released hydrogel and the water added during the pulverization, For, a decay curve is obtained. The obtained two-component decay curve is analyzed by the following equation (1), and the relaxation time of the two components is determined, whereby the dispersibility of the hydrogel crushed dispersion liquid can be determined. The pulse NMR can be measured, for example, by the method (measurement apparatus and measurement conditions) performed in the examples described later.

Fitting function: A ₂ exp (−x / τ ₂ ) + A ₃ exp (−x / τ ₃ )
Formula (1)
(A ₂ and A ₃ in the formula: constants representing the following component ratios, τ ₂ restraint water relaxation time, τ ₃ : free water relaxation time, x: time)

  In the pulsed NMR measurement described above, the mobility of water molecules as a solvent can be evaluated. An increase in relaxation time means an increase in motility.

In the binder composition of the present embodiment, when the solid content concentration is 5.5% by weight, the restraint water relaxation time τ _{2 in the} water relaxation time by the pulse NMR measurement described above is 20 milliseconds or more, and free water The relaxation time τ ₃ is 300 milliseconds or more.

  In the present embodiment, the solid content concentration is a concentration calculated by the following method. That is, first, the pulverized solution (polymer aqueous solution) is weighed in a 1 g glass petri dish and vacuum dried at 105 ° C. for 6 hours. Thereafter, the obtained film weight is weighed and multiplied by 100 to calculate the solid content concentration (% by weight).

Τ ₂ having a small relaxation time represents low motility, and specifically suggests the abundance and size of the hydrogel. In the present embodiment, the constraint water relaxation time τ ₂ may be 20 milliseconds or more, but is more preferably 30 milliseconds or more. The fact that the time of relaxation time τ ₂ of constraint water is shorter than 20 milliseconds indicates that the amount of hydrogel having low mobility is large. In this case, the hydrogel is not sufficiently crushed, suggesting that the crushed hydrogel diameter is large. When the diameter of the crushed hydrogel is large, the dispersibility of the binder in the electrode is lowered and the binding property is lowered, which is not preferable. The upper limit value of the constraint water relaxation time τ ₂ is not particularly limited, but there is a limit to the hydrogel diameter obtained by the crushing force. In the above crushing method, the relaxation time τ ₂ does not reach 200 milliseconds or more.

On the other hand, τ ₃ having a large relaxation time represents a high degree of mobility, and specifically suggests a free water amount. In this embodiment, the relaxation time τ ₃ of free water may be 300 milliseconds or more, but is more preferably 400 milliseconds or more. The fact that the relaxation time τ ₃ of the free water is short is not preferable because it indicates that the hydrogel is not sufficiently crushed and suggests a decrease in binding properties for the same reason as τ ₂ . The upper limit value of the relaxation time τ ₃ of the free water is not particularly limited, but an increase in the amount of free water promotes a decrease in the solution viscosity and may adversely affect the leveling property at the time of electrode preparation. It is preferable that

In the present embodiment, the means for adjusting the relaxation time τ ₂ and the relaxation time τ ₃ to the ranges as described above is not particularly limited. For example, the material composition is adjusted to the composition described later. Can do. In particular, the relaxation time τ ₂ can be adjusted by the material composition. Moreover, relaxation time (tau) ₃ can be adjusted with the solid content concentration of the hydrogel contained in the composition of this embodiment. For example, if the solid content concentration of the gel is small, the amount of free water released by crushing increases and τ ₃ also increases.

  The composition of the binder composition of the present embodiment is not particularly limited as long as it has the above characteristics, but in order to obtain the binder composition having the characteristics described above, for example, the binder of the present embodiment The composition preferably contains a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid and a polyamine.

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

In this 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 the present 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 may 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 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 alkylmaleimide such as ethylmaleimide, N-propylmaleimide, Nn-butylmaleimide, Nt-butylmaleimide, N-cyclohexylmaleimide, N-methylphenylmaleimide, N-ethyl Phenyl male N-substituted alkylphenylmaleimide such as 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-ethylmaleic acid) 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- Methoxyphenylmaleimide, 2-methyl-N-substituted alkoxyphenylmaleimide such as 2-methyl-N-ethoxyphenylmaleimide), and further halides thereof (for example, 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.

As for the content rate of each said structural unit in the copolymer of this embodiment, it is desirable for (A) / (B) to exist in the range of 1 / 1-1 / 3 by 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. In particular, the molar ratio of (A) / (B) is desirably 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 for obtaining the copolymer of the present embodiment varies depending on the composition of the target copolymer, but α- 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% with respect to maleic acids, but is preferably 0.5 to 3 mol%. 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 the present embodiment usually has an average molecular weight of 10,000 to 500,000. A more preferred average molecular weight is 15,000-450,000. 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 this 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 0.05-2. The copolymer of the present 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, a basic substance containing a monovalent metal and / or ammonia as the basic substance from the viewpoint of binding properties as a binder. Is preferably used.

  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 of carboxylic acid produced from maleic acids. It is preferably in the range of 1 mol, and more preferably, a neutralized one in the range of 0.4 to 1 mol is used. 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 containing monovalent metal and / or ammonia is not particularly limited and is appropriately selected depending on the purpose of use and the like, but usually in the maleic acid copolymer. The amount is preferably 0.1 to 2 mol per mol of maleic acid unit. If it is such usage-amount, it will be possible to adjust pH of the binder composition of this embodiment to the predetermined range. In addition, the usage-amount of the basic substance containing a monovalent metal becomes like this. Preferably, it is 0.6-2.0 mol per mol of maleic acid units in a maleic acid copolymer, More preferably, it is 0.7-2. When the amount is 0 mol, a water-soluble copolymer salt with little alkali residue can be obtained.

  The reaction of the α-olefin-maleic acid copolymer with a basic substance containing a monovalent metal and / or an amine such as ammonia can be carried out according to a conventional method, but is carried out in the presence of water, and α- A method of obtaining a neutralized olefin-maleic acid copolymer as an aqueous solution 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, tertiary amines such as trimethylamine, triethylamine and tributylamine, And polyamines such as ethylenediamine, butylenediamine, diethyleneimine, triethyleneimine, and polyethyleneimine. Among these, ammonia, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferable. 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. Moreover, if it is in the range which does not have a bad influence on battery performance, the basic substance containing alkali metal hydroxides, such as sodium hydroxide, is used together, and the neutralized product of alpha-olefin-maleic acid copolymer May be prepared.

  The binder composition of the present embodiment preferably further contains polyamines, whereby a hydrogel can be formed. By hydrogelling, as described above, binding properties and toughness can be imparted to the binder composition.

  The polyamines used in the present embodiment are not limited as long as they are electrochemically stable, but include low molecular weight substances having a molecular weight of less than 300 and / or high molecular weight substances having a molecular weight of 300 or more.

  Specific examples of low molecular weight polyamines include ammonia, ammonium salts, aliphatic monoamines, aromatic monoamines, heterocyclic monoamines, aliphatic polyamines, aromatic polyamines, and heterocyclic polyamines. It is done. Preferable specific examples include, for example, ammonia; ammonium salts such as tetraethylammonium hydroxide; aliphatic monoamines such as ethylamine, monoethanolamine, diethylamine, triethylamine, glycine, and guanidine carbonate; aromatic monoamines such as aniline and benzylamine; Heterocyclic monoamines such as imidazole; Aliphatic polyamines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and guanidine; Aromatic polyamines such as phenylenediamine; Heterocyclic groups such as piperazine and N-aminoethylpiperazine And polyamines.

  Specific examples of the high molecular weight polyamines include amino group-containing polymers, and preferred specific examples thereof include polyethyleneimine, polytetramethyleneimine, polyvinylamine, polyallylamine, dicyandiamide-formalin condensate, dicyandiamide-alkylene ( Polyamine) condensates and the like. These may be used alone or in combination. In view of availability and economy, polyethyleneimine is preferably used.

  The molecular weight of these polyamines is not particularly limited, and the average molecular weight is in the range of 50 to 200,000, more preferably in the range of 100 to 180000, and most preferably in the range of 200 to 100,000. The addition amount of the polyamines is not particularly limited, but is usually 0.01 to 10 parts by weight with respect to 100 parts by weight of the α-olefin-maleic acid copolymer (solid content). Preferably, it is the range of 0.05 weight part-6 weight part. An excessive addition amount is not preferable because it forms a complex salt with an α-olefin-maleic acid copolymer, and a strong hydrogelation due to multi-crosslinking progresses, and water is constrained and difficult to dry. Is not preferable because 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. When added later, a hydrogel is formed by crosslinking with the added polyamines. Usually, the temperature for hydrogelation is not particularly limited, but hydrogelation proceeds rapidly by heating at 20 ° C. or higher, preferably 30 ° C. or higher. The time required for hydrogelation depends on temperature and is not limited. Usually, hydrogelation is completed in about 0.1 hour to 2 months.

  Next, in this embodiment, the ring-opening rate of the copolymer represents the hydrolysis rate of the maleic anhydride sites that polymerize 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 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. The degree of neutralization in this case is not particularly limited. However, when used as a binder, in consideration of reactivity with the electrolytic solution, usually with respect to 1 mol of carbonyl acid generated by ring opening, A range of 0.5 to 1 mol is preferable, and a neutralized range of 0.6 to 1 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.

  Moreover, the nonaqueous electrolyte battery electrode binder composition of the present embodiment is usually a nonaqueous electrolyte battery electrode slurry composition (hereinafter, referred to as “nonaqueous electrolyte battery electrode slurry”), which further contains an active material and water in addition to the binder composition described above. It is preferably used as a slurry composition).

  Further, in the present embodiment, the nonaqueous electrolyte battery electrode is characterized in that a mixed layer containing at least the binder composition and the active material of the present embodiment is bound to a current collector. This 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 the neutralized salt of the α-olefin-maleic acid copolymer used relative to 100 parts by weight of the active material is usually 0.1 to 4 parts by weight. The amount is preferably 0.3 to 3 parts by weight, more preferably 0.5 to 2 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 a solvent in the slurry composition for electrodes of this 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 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. As such an organic solvent, those having a boiling point of 100 ° C. or more and 300 ° C. or less at normal pressure are preferable, 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; organic dispersion media such as sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane.

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

  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.

  The amount of the thickener used in the slurry composition as needed is preferably about 0.1 to 4 parts by weight, more preferably 0.3 to 3 parts by weight with respect to 100 parts of the negative electrode active material. More preferably, it is 0.5 to 2 parts by weight. If the thickener is too small, the viscosity of the secondary battery negative electrode slurry may be too low and the thickness of the mixed layer may be reduced. Conversely, if the thickener is excessively large, the discharge capacity may be reduced. .

  Moreover, as a conductive support agent mix | blended with a slurry composition as needed, metal powder, a conductive polymer, acetylene black etc. are mentioned, for example. The amount of the conductive aid used is usually preferably 0.5 to 10 parts by weight, more preferably 1 to 7 parts by weight with respect to 100 parts by weight of the active material.

  The current collector used for the nonaqueous electrolyte battery 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 nonaqueous electrolyte battery electrodes of the present invention is most apparent. The shape of the current collector is not particularly limited, but usually a sheet shape having a thickness of about 0.001 to 0.5 mm is preferable.

  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 0.005. 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 nonaqueous electrolyte battery having the above electrode. When the electrode is used as a negative electrode, the nonaqueous electrolyte battery of this embodiment usually includes the electrode (negative electrode), a 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.

  A solvent (electrolyte solvent) for dissolving such an electrolyte 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 Terigres; 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.

  Although there is no limitation in particular as a method of manufacturing the nonaqueous electrolyte battery of this embodiment, For example, the following manufacturing method is illustrated. 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 this embodiment is a battery that achieves both improved adhesion and improved battery characteristics, and is useful for various applications. For example, the battery is very useful as a battery used in a portable terminal that is required to be small, thin, light, and have high performance.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
<Binder composition for negative electrode>
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring opening rate 96%) was prepared as a binder composition for a negative electrode. Further, a 10% by weight aqueous solution of polyethyleneimine (PEI, Nippon Shokubai Co., Ltd., average molecular weight 10,000) as an amine was prepared and mixed at a weight ratio of 10% by weight aqueous resin: 10% by weight PEI aqueous solution = 99.9: 0.1. did. The obtained mixture was heated to 90 ° C. and stirred for 2 hours to obtain a hydrogel having a solid content of 11.1% by weight. The obtained hydrogel was stirred for 2 hours at a peripheral speed of 11 m / s using a mixer mill (manufactured by Hiroshima Metal & Machinery, “UAM-05”), and the hydrogel was crushed and uniformly dispersed in the liquid to obtain a solid concentration of 5 A 5% by weight hydrogel pulverized dispersion was obtained. Thereafter, pulse NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and the free water relaxation time τ ₃ were measured under the following conditions and methods. Table 1 shows the restricted water relaxation time τ ₂ and the free water relaxation time τ ₃ obtained.

<Measurement Method of Pulse NMR and Calculation Method of Restrained Water Relaxation Time τ ₂ and Free Water Relaxation Time τ ₃ >
The hydrogel pulverized product dispersion obtained in each Example or Comparative Example described later was put into an NMR tube. This NMR tube was stored in a thermostatic bath at 25 ° C. for 30 minutes, and the measurement sample was measured for ¹ H spin-spin relaxation time using pulse NMR (“minispec mq20 WVT” manufactured by Bruker BioSpin Corporation). did. The measurement conditions are as follows.
・ Pulse sequence: Carr-Purcell-Meiboom-Gill (CPMG method)
・ RF pulse width: 8.2 μs
・ Measurement temperature: 25 ℃
Dummy shot: 4 times The relaxation curve obtained by the above measurement was fitted to the above equation (1) by the linear least square method, and the restraint water relaxation time τ ₂ and the free water relaxation time τ ₃ were calculated.

<Preparation of slurry for negative electrode>
The electrode slurry was prepared by using 3.125 parts by weight of a hydrogel pulverized dispersion as a negative electrode binder composition as a solid content and 100 parts by weight of natural graphite (DMGS, manufactured by BYD) as an active material for the negative electrode. As an agent (conductivity imparting agent), Super-P (manufactured by Timcal Co., Ltd.) as a solid was added in an amount of 1.042 parts by weight to a dedicated container, and kneaded using a planetary stirrer (ARE-250, manufactured by Shinky Corporation). In order to adjust the viscosity of the slurry, an electrode coating slurry was prepared by adding water at the time of kneading and kneading again. The composition ratio of the active material and the binder in the slurry is, as a solid content, graphite powder: conductive aid: binder composition = 100: 1.042: 3.125.

<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 Co., Ltd.), and heated at 80 ° C. for 30 minutes with a hot air dryer (Yamato Scientific). After the primary drying, a rolling process was performed using a roll press (made by Hosen) to produce an electrode having an active material layer thickness of 40 μm. Then, after punching out as a battery electrode (φ14 mm), a coin battery electrode was produced by secondary drying under reduced pressure conditions at 140 ° C. for 3 hours.

<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.). By attaching the slurry-coated surface of the coated electrode for a battery obtained above and a stainless steel plate using a double-sided tape (double-faced tape made by Nichiban), and peeling the electrode part from the stainless steel plate, 180 ° peel strength (peeling) A width of 10 mm and a peeling speed of 100 mm / min) were measured. The results are shown in Table 1 below.

<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)) of type 1 test equipment. Used. The electrode cracks were confirmed visually, and the results of the minimum mandrel diameter at which no cracks occurred are shown in Table 1 below. In addition, toughness is so high that a mandrel diameter is small, and it is preferable to use it as an electrode as it is 5 mm or less.

<Production of battery>
The battery coating electrode obtained above was transferred to a glove box (Miwa Seisakusho) under an argon gas atmosphere. A metal lithium foil (thickness 0.2 mm, φ16 mm) was used for the positive electrode. Polypropylene-based separator (Celgard # 2400, manufactured by Polypore) is used as the separator, and lithium hexafluorophosphate (LiPF ₆ ) ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are used as the electrolyte and vinylene carbonate (VC). A coin battery (2032 type) was produced using a mixed solvent system (1M-LiPF ₆ , EC / EMC = 3/7 vol%, VC 2 wt%) to which was added.

<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)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring opening rate 96%) was prepared as a binder composition for a negative electrode. Furthermore, as a polyamine, a 10% by weight aqueous solution of polyethyleneimine (PEI, manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight 10,000) was prepared, and mixed at a weight ratio of 10% by weight aqueous resin: 10% by weight PEI aqueous solution = 99: 1. did. Then, to adjust the solid content concentration 5.5 wt% of the hydrogel crushed material dispersion in a manner similar to Example 1, the pulse NMR of the resulting hydrogel crushed material dispersion is measured, and the restraining water relaxation time tau ₂ Free water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Example 3)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, degree of neutralization 0.5, ring opening rate 96%) was prepared as an electrode binder composition. Further, a 10% by weight aqueous solution of polyethyleneimine (PEI, manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight 10,000) is prepared as an amine, and the resin is mixed at a weight ratio of 10% by weight aqueous solution: PEI 10% by weight aqueous solution = 98: 2. did. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

Example 4
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, degree of neutralization 0.5, ring opening rate 96%) was prepared as an electrode binder composition. Further, a 10% by weight aqueous solution of polyallylamine (PAA, Nittobo Medical, average molecular weight 1600) as an amine was prepared and mixed at a weight ratio of 10% by weight aqueous resin: 10% by weight aqueous PEI = 99: 1. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Example 5)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, degree of neutralization 0.5, ring opening rate 96%) was prepared as an electrode binder composition. Further, ethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.) as a 10 wt% aqueous solution was prepared as an amine, and mixed in a weight ratio of 10 wt% resin aqueous solution: 10 wt% PEI aqueous solution = 99: 1. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Example 6)
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 98%) was prepared as an electrode binder composition. Further, a 10% by weight aqueous solution of polyethyleneimine (PEI, manufactured by Nippon Shokubai Co., Ltd., average molecular weight 10,000) was prepared as an amine, and mixed at a weight ratio of 10% by weight resin aqueous solution: 10% by weight PEI aqueous solution = 99: 1. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Example 7)
A 10% by weight aqueous solution of a water-soluble lithium-modified ethylene-maleic anhydride copolymer resin (average molecular weight 100,000, neutralization degree 0.5, ring-opening rate 99%) was prepared as an electrode binder composition. Further, a 10% by weight aqueous solution of polyethyleneimine (PEI, manufactured by Nippon Shokubai Co., Ltd., average molecular weight 10,000) was prepared as an amine, and mixed at a weight ratio of 10% by weight resin aqueous solution: 10% by weight PEI aqueous solution = 99: 1. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Comparative Example 1)
A 10% by weight aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring opening rate 96%) was prepared as a binder composition for a negative electrode. Pulse NMR was measured with respect to the obtained aqueous solution, and restraint water relaxation time τ ₂ and free water relaxation time τ ₃ were measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Comparative Example 2)
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 98%) was prepared as a binder composition for the negative electrode. Pulse NMR was measured with respect to the obtained aqueous solution, and restraint water relaxation time τ ₂ and free water relaxation time τ ₃ were measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Comparative Example 3)
A 10% by weight aqueous solution of a water-soluble lithium-modified ethylene-maleic anhydride copolymer resin (average molecular weight 100,000, neutralization degree 0.5, ring opening rate 99%) was prepared as a binder composition for the negative electrode. Pulse NMR was measured with respect to the obtained aqueous solution, and restraint water relaxation time τ ₂ and free water relaxation time τ ₃ were measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Comparative 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 0.5, ring opening rate 96%) was prepared as a binder composition for a negative electrode. Furthermore, as a polyamine, a 10% by weight aqueous solution of polyethyleneimine (PEI, manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight 10,000) was prepared, and mixed at a weight ratio of 10% by weight aqueous resin: 10% by weight aqueous PEI = 95: 5. did. Thereafter, a hydrogel pulverized dispersion with a solid content concentration of 5.5% by weight was prepared in the same manner as in Example 1, and the pulsed NMR of the obtained hydrogel pulverized dispersion was measured, and the restraint water relaxation time τ ₂ and free The water relaxation time τ ₃ was measured. Moreover, the coated electrode was produced by the method similar to the said Example 1, and the toughness test and the peeling strength measurement were performed. Furthermore, the coin battery using this electrode was obtained and the charge / discharge characteristic test was done. These evaluation results are shown in Table 1.

(Discussion)
Implementation of application of a pulverized dispersion with a restraint water relaxation time τ ₂ of 20 milliseconds or more and a free water relaxation time τ ₃ of 300 milliseconds or more in the relaxation time of water by pulse NMR at a solid content concentration of 5.5% by weight In the example, since the degree of crosslinking was high due to the addition of polyamines and the hydrogel was sufficiently crushed, high electrode adhesion was exhibited. Furthermore, even when a crosslinking agent was added, no increase in resistance was observed, indicating that a DC resistance equivalent to that of an unadded product was obtained.

On the other hand, in Comparative Examples 1 to 3 in which the polyamines were not added, the crosslinking reaction did not occur and the hydrogel was not formed. Therefore, the restricted water relaxation time τ ₂ and free water relaxation defined in the present invention. The time τ ₃ was out of the specified range, resulting in low binding properties. Further, in Comparative Example 4 in which a large amount of polyamines were added, the free water relaxation time τ ₃ was far below the specified range, and thus the resistance value was increased in addition to the decrease in binding properties. Regarding the binding property, it is considered that as a result of the reduction in crushing efficiency accompanying the high cross-linking, the diameter of the hydrogel dispersed in the liquid is large, and the binder dispersibility in the electrode is reduced. The increase in direct current resistance is presumed to be caused by the partial peeling of the electrode layer accompanying the decrease in the binding force in addition to the addition of many crosslinking agents.

Claims (5)

Including a hydrogel composed of a water-soluble polymer,
When the solid concentration is 5.5% by weight, the water relaxation time τ _{2 in the} water relaxation time by pulse NMR is 20 milliseconds or more, and the free water relaxation time τ ₃ is 300 milliseconds or more. A binder composition for a non-aqueous electrolyte battery electrode, characterized in that   The binder composition for a nonaqueous electrolyte battery electrode according to claim 1, wherein the hydrogel contains a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid, and a polyamine.   A slurry composition for a nonaqueous electrolyte battery electrode, comprising the binder composition according to claim 1 or 2, an active material, and water.   A nonaqueous electrolyte battery electrode formed by binding a mixed layer containing the binder composition according to claim 1 or 2 and an active material to a current collector.   A nonaqueous electrolyte battery comprising the nonaqueous electrolyte battery electrode according to claim 4.