KR102303725B1 - Thermal crosslinking type slurry for lithium ion battery and method for producing same, electrode for lithium ion battery, separator for lithium ion battery, separator/electrode layered product for lithium ion battery and lithium ion battery - Google Patents

Abstract

(Project) An object of the present invention is to provide a slurry for a thermally crosslinkable lithium ion battery and a method for manufacturing the same, an electrode for a lithium ion battery, a separator for a lithium ion battery, a separator/electrode laminate for a lithium ion battery, and a lithium ion battery.
(Solution) The present disclosure relates to a water-soluble poly(meth)acrylamide containing 50 mol% or more of the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) with respect to 100 mol% of the structural unit. (A), a water-soluble crosslinking agent (A1) containing at least one selected from the group consisting of formaldehyde, glyoxal, hexamethylenetetramine, urea formaldehyde resin, and methylolmelamine resin, and a thermal crosslinking type containing water A slurry for lithium ion batteries is provided.

Description

Slurry for thermal crosslinking lithium ion battery and manufacturing method thereof, electrode for lithium ion battery, separator for lithium ion battery, separator/electrode laminate for lithium ion battery, and lithium ion battery TECHNICAL FIELD ELECTRODE FOR LITHIUM ION BATTERY, SEPARATOR FOR LITHIUM ION BATTERY, SEPARATOR/ELECTRODE LAYERED PRODUCT FOR LITHIUM ION BATTERY AND LITHIUM ION BATTERY}

The present disclosure relates to a slurry for a thermal crosslinking type lithium ion battery and a method for manufacturing the same, an electrode for a lithium ion battery, a separator for a lithium ion battery, a separator/electrode laminate for a lithium ion battery, and a lithium ion battery.

BACKGROUND ART Lithium ion batteries are small and lightweight, have high energy density, and have characteristics that can be repeatedly charged and discharged, and are used in a wide range of applications. Therefore, in recent years, improvement of battery members, such as an electrode and a separator, is examined for the purpose of further performance improvement in a lithium ion battery.

Both the positive electrode and the negative electrode of a lithium ion battery are made by dispersing an electrode active material and a binder resin in a solvent to form a slurry. ) is coated on both sides, the solvent is dried and removed to form an electrode layer, and then this is compressed and molded with a roll press machine or the like.

In recent years, the electrode for lithium ion batteries WHEREIN: From a viewpoint of raising a battery capacity, various electrode active materials are proposed as an electrode active material. However, depending on the electrode active material, it is easy to expand and contract according to charging and discharging. For this reason, the lithium ion battery electrode has a problem that the volume change occurs from the initial stage of repeated charging and discharging (spring back nature), and electrical characteristics such as cycle characteristics of the lithium ion battery using the same are easily reduced. .

Then, in the four seasons, examination for trying to solve the said subject with binder resin is made|formed, for example, an emulsion crosslinking system (patent document 1) and N-methylolacrylamide (patent document 2) are proposed.

About the separator of a lithium ion battery, the heat-resistant separator which formed the coating layer (heat-resistant layer) containing ceramic microparticles|fine-particles and a binder on the surface of a polyolefin microporous film is recently proposed with respect to the separator of a lithium ion battery. It is known that the coating layer has an effect of suppressing the shrinkage of the separator even when exposed to high temperatures. However, the obtained heat-resistant separator had a problem that the adhesion between the coating layer and the polyolefin microporous film could not be maintained due to deformation such as warpage during transport in a production line or warpage in a battery cell, and thus easily fall off.

Therefore, in the four seasons, studies are being made to solve the above problems with a binder resin, for example, a separator comprising polyacrylic acid in which polyacrylic acid is crosslinked with a metal cation ( Patent document 3) is also proposed. Furthermore, a porous membrane composition for lithium ion secondary batteries (Patent Document 4) comprising a water-soluble thickener containing a carboxyl group, a carbodiimide compound crosslinking agent, and a particulate polymer has been proposed.

International Publication No. 2016/159198 Japanese Patent Laid-Open No. 2015-185530 Japanese Patent Laid-Open No. 2016-012478 Japanese Patent Publication No. 6187464

Regarding the electrode of a lithium ion battery, although patent document 1 proposes the crosslinked body of an emulsion, although the degree of crosslinking can be raised, the effect of spring back resistance is insufficient.

Since N-methylolacrylamide described in Patent Document 2 has crosslinking properties in the resin itself, gelation is a problem. Therefore, since the inflow amount cannot be increased and the degree of crosslinking cannot be increased, the effect of springback resistance is insufficient.

With respect to the separator of a lithium ion battery, since the crosslinking effect is remarkably low in the polyacrylate which polyacrylic acid described in patent document 3 was bridge|crosslinked with a metal cation, there exists a subject that the adhesive improvement effect is low.

In addition, Patent Document 4 proposes a porous layer for a separator using a composition containing a specific water-soluble thickener and a carbodiimide compound in addition to a binder. However, since the binder and the carbodiimide compound have high reactivity, the stability of the slurry is poor. It tends to gel easily. For this reason, the case where the thickness at the time of application|coating is uneven arises because microparticles|fine-particles aggregate and settle over time, and it is difficult to create a uniform porous film.

Therefore, the problem to be solved by the present invention is an electrode capable of imparting excellent springback resistance and electrical properties to a lithium ion battery, and excellent heat shrinkage resistance, dust fall-off proofness, and substrate It shall provide the thing which can manufacture the separator which can provide adhesiveness, a rate characteristic, and an output characteristic to a lithium ion battery. In addition, in the present disclosure, the anti-slip property means the bonding property between the ceramic fine particles, and the adhesion to the substrate refers to the adhesion between the substrate and the layer (coating layer) obtained by applying the slurry according to the present invention to the substrate and drying it. means adhesion.

As a result of intensive studies to solve the above problems, the present inventors use a slurry for thermal crosslinking lithium ion batteries containing poly(meth)acrylamide prepared using a specific monomer, a water-soluble crosslinking agent, and water, thereby solving the above problems Found what could be done, and came to complete the present invention.

The present disclosure provides the following items.

(Item 1)

Water-soluble poly(meth)acrylamide (A) containing 50 mol% or more of the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) with respect to 100 mol% of the structural unit;

A water-soluble crosslinking agent (A1) comprising at least one selected from the group consisting of formaldehyde, glyoxal, hexamethylenetetramine, urea formaldehyde resin, and methylolmelamine resin;

and water

Slurry for thermal crosslinking lithium-ion batteries.

(Item 2)

In the water-soluble poly(meth)acrylamide (A), the water-soluble crosslinking agent (A1) is added in an amount of 0.001 to 100% by mass of the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) The slurry for thermal crosslinking type lithium ion batteries as described in the said item containing 3.0 mass %.

(Item 3)

The slurry for a thermally crosslinkable lithium ion battery according to the above item comprising an electrode active material (B).

(Item 4)

The slurry for a thermal crosslinking type lithium ion battery as described in the said item in which the said electrode active material (B) contains 10 mass % or more of silicon or silicon oxide.

(Item 5)

The slurry for a thermally crosslinkable lithium ion battery as described in the above, comprising ceramic fine particles (C).

(Item 6)

The method for producing a slurry for a thermally crosslinkable lithium ion battery according to any one of the above items, comprising the step of adding the water-soluble crosslinking agent (A1) to an aqueous solution containing the water-soluble poly(meth)acrylamide (A).

(Item 7)

An electrode for a lithium ion battery obtained by applying the slurry for a thermally crosslinkable lithium ion battery according to any one of the above items to a current collector and performing a thermal crosslinking reaction.

(Item 8)

A lithium ion battery comprising the electrode for a lithium ion battery according to the above item.

(Item 9)

A lithium ion battery separator obtained by applying the thermally crosslinkable lithium ion battery slurry described in the above item to a porous polyolefin resin substrate or plastic nonwoven fabric and thermally crosslinking it.

(Item 10)

The slurry for thermal crosslinking lithium ion batteries described in the above item,

A separator/electrode laminate for lithium ion batteries obtained by coating on the active material side of an electrode material and thermally crosslinking.

(Item 11)

A lithium ion battery comprising the separator for a lithium ion battery according to the above item and/or the separator/electrode laminate for a lithium ion battery according to the above item.

In the present disclosure, one or a plurality of the above-described features may be provided by further combination in addition to the specified combination.

By using the aqueous binder solution for lithium ion batteries and the slurry for lithium ion batteries of the present invention, it is possible to provide a lithium ion battery in which battery capacity is maintained and springback resistance is improved.

By using the aqueous binder solution for lithium ion batteries and the slurry for lithium ion batteries of the present invention, it is possible to provide a separator for lithium ion batteries with improved heat shrinkage resistance, slip resistance, substrate adhesion, rate characteristics, and output characteristics.

Throughout the present disclosure, numerical ranges such as respective physical property values and content may be appropriately set (for example, by selecting from the values of upper and lower limits described in each item below). Specifically, for the numerical value α, when the upper limit of the numerical value α is exemplified by A1, A2, A3, etc., and the lower limit of the numerical value α is exemplified by B1, B2, B3, etc., the range of the numerical value α is A1 or less, A2 Below, A3 or less, B1 or more, B2 or more, B3 or more, A1 to B1, A1 to B2, A1 to B3, A2 to B1, A2 to B2, A2 to B3, A3 to B1, A3 to B2, A3 to B3, etc. This is exemplified.

[1.Slurry for thermal crosslinking lithium ion battery: also called slurry for lithium ion battery, also called slurry]

The present disclosure relates to a water-soluble poly(meth)acrylamide (A) containing 50 mol% or more of a structural unit derived from an N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) with respect to 100 mol% of the structural unit;

A water-soluble crosslinking agent (A1) comprising at least one selected from the group consisting of formaldehyde, glyoxal, hexamethylenetetramine, urea formaldehyde resin, and methylolmelamine resin;

And it provides a slurry for a thermal crosslinking type lithium ion battery containing water.

In the present disclosure, "slurry" means a suspension of liquid and solid particles.

In this indication, "water solubility" means that when 0.5 g of this compound is melt|dissolved in 100 g of water at 25 degreeC, an insoluble content is less than 0.5 mass % (less than 2.5 mg).

In the present disclosure, “(meth)acryl” means “at least one selected from the group consisting of acryl and methacryl”. Similarly, "(meth)acrylate" means "at least one selected from the group consisting of acrylates and methacrylates." Moreover, "(meth)acryloyl" means "at least 1 selected from the group which consists of acryloyl and methacryloyl."

In one embodiment, the water-soluble poly(meth)acrylamide (A) is obtained by polymerizing the monomer group containing the N-unsubstituted or monosubstituted (meth)acrylamide group containing compound (a). In addition, in this disclosure, "poly(meth)acrylamide" means a (co)polymer ((co)polymer) obtained by polymerizing a group of monomers containing a (meth)acrylamide group-containing compound.

In the present disclosure, "N-unsubstituted (meth)acrylamide group-containing compound" means a compound in which two hydrogens on nitrogen of the (meth)acrylamide group are not substituted with groups other than hydrogen. "N-1 substituted (meth)acrylamide group-containing compound" means a compound in which one hydrogen on nitrogen of the (meth)acrylamide group is substituted with groups other than hydrogen. The N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) may be used independently or may use 2 or more types together.

The N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) has the following structural formula

[In formula, ^{R A1} is a hydrogen or a methyl group, ^{R A2} and R ^A3 is a one is hydrogen and the other one is hydrogen, a substituted or unsubstituted alkyl group, an acetyl group or a sulfonic acid group, ^{R A4} and R ^A5 each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a carboxyl group, a hydroxy group, an amino group ^{<-NR Aa R Ab (R} Aa ^Ab and R are each independently hydrogen or substituted or unsubstituted alkyl)>, and the like such as an acetyl group, a sulfonic acid group .]

The compound represented by, etc. are illustrated.

Examples of the alkyl group include a normal chain alkyl group, a branched alkyl group, and a cycloalkyl group.

Straight-chain alkyl group is represented by a general formula -C _n H _{2n + 1 (n} is an integer of 1 or more). Examples of the straight-chain alkyl group include a methyl group, an ethyl group, a propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decamethyl group and the like.

The branched alkyl group is a group in which at least one hydrogen of the straight-chain alkyl group is substituted with an alkyl group. Examples of the branched alkyl group include a diethylpentyl group, a trimethylbutyl group, a trimethylpentyl group, and a trimethylhexyl group.

Examples of the cycloalkyl group include a monocyclic cycloalkyl group, a cross-linked cycloalkyl group, and a condensed cyclic cycloalkyl group.

In the present disclosure, monocyclic means a cyclic structure that does not have a bridged structure therein formed by a covalent bond of carbon. In addition, the condensed ring means a cyclic structure in which two or more monocyclic rings share two atoms (that is, only one side of each ring is shared (condensed) with each other). Cross-linking refers to a cyclic structure in which two or more monocycles share three or more atoms.

Examples of the monocyclic cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclodecyl group, and a 3,5,5-trimethylcyclohexyl group.

Examples of the cross-linked cycloalkyl group include a tricyclodecyl group, an adamantyl group, and a norbornyl group.

Examples of the condensed cyclic cycloalkyl group include a bicyclodecyl group.

Examples of the N-unsubstituted (meth)acrylamide group-containing compound include (meth)acrylamide, maleic acid amide, and salts thereof.

The N-1 substituted (meth)acrylamide group-containing compound is N-isopropyl (meth)acrylamide, N-methylol (meth)acrylamide, diacetone (meth)acrylamide, (meth)acrylamide t-butyl Sulfonic acid, hydroxyethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N,N-methylenebis(meth)acrylamide, Nt-butyl(meth)acrylamidesulfonic acid, its salt, etc. are illustrated.

The salt is dimethylaminopropyl (meth)acrylamide methyl quaternary salt, dimethylaminoethyl (meth)acrylate benzyl chloride quaternary salt, 3-((meth)acrylamide)propyltrimethylammonium chloride quaternary salt, 3-(( Meth)acrylamide) propyltrimethylammonium methyl sulfate quaternary salt etc. are illustrated.

In one embodiment, the upper limit of the ratio of the structural units derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) contained in the water-soluble poly(meth)acrylamide (A) is 99.95 , 99.8, 99.7, 99.2, 95, 90, 85, 80, 75, 70, 65 mol% and the like, and the lower limit is 99.8, 99.7, 99.2, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50 mol%, etc. are illustrated. In one embodiment, it is preferable that the ratio of the said structural unit is 50 mol% or more, It is more preferable that it is 55.0-99.8 mol%, It is especially preferable that it is 60.0-99.7 mol%.

The upper limit of the ratio of the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group containing compound (a) contained in 100 mass % of water-soluble poly(meth)acrylamide (A) is 100, 90, 80 , 70, 60, 50, 45 mass % etc. are illustrated, and 90, 80, 70, 60, 50, 45, 40 mass % etc. are illustrated as for a lower limit. In one embodiment, 40-100 mass % is preferable, It is more preferable that it is 45-100 mass %, It is especially preferable that it is 50-100 mass %.

By containing the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) in a specific amount in the component (A), the dispersibility of the electrode active material, filler, ceramic fine particles, etc. is improved and uniform Since it becomes possible to manufacture a layer (electrode active material layer, a ceramic fine particle layer, etc.), a structural defect disappears and it shows favorable charging/discharging characteristic. Moreover, since the oxidation resistance and reduction resistance of a polymer become favorable when the structural unit derived from a (meth)acrylamide group containing compound is contained in (A) component in a specific amount, the high voltage Deterioration is suppressed and good charging/discharging durability characteristics are exhibited.

(The monomer which is not (A) component: It is also called (b) component)

In the monomer group, a monomer (component (b)) other than the component (a) can be used as long as the effect desired by the present invention is not impaired. (b) A component may use various well-known things independently, and may use 2 or more types together.

(b) component is an N,N-disubstituted (meth)acrylamide group-containing compound, acid group-containing monomers such as unsaturated carboxylic acid, unsaturated sulfonic acid, and unsaturated phosphoric acid, unsaturated carboxylic acid ester, α,β-unsaturated nitrile, Conjugated dienes, aromatic vinyl compounds, and the like are exemplified.

The N,N-2-substituted (meth)acrylamide group-containing compound has the following structural formula

( ^{Wherein, RB1} is hydrogen or a methyl group, ^RB2 and ^RB3 are each independently a substituted or unsubstituted alkyl group, acetyl group, or sulfonic acid group, or ^RB2 and ^RB3 together form a ring structure, ^B4 and R ^B5 each independently represent a hydrogen, a substituted or unsubstituted alkyl group, a carboxyl group, a hydroxy group, an amino group ^{(-NR R} Ba ^{Bb (R Ba} and R ^Bb are each independently hydrogen or substituted or unsubstituted alkyl group)), an acetyl group a sulfonic acid group. the substituent of the substituted alkyl group include a hydroxy group, an amino group, like an acetyl group, a sulfonic acid group and the like. Further groups which R ^B2 and R ^B3 are formed a ring structure together, morpholino pole group-(morpholyl基) etc. may be mentioned .)

The compound represented by and the like are exemplified.

The N,N-disubstituted (meth)acrylamide group-containing compound described above is N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth) ) acrylamide, (meth)acryloylmorpholine and its salts are exemplified. Examples of the salt include those described above.

Although content of the N,N-disubstituted (meth)acrylamide group containing compound in 100 mol% of structural units is not specifically limited, In one embodiment, the said N,N-disubstituted (meth)acrylamide group In consideration of the affinity of the contained compound, less than 50 mol% (for example, less than 40, 30, 20, 15, 10, 9, 5, or 1 mol%) in 100 mol% of the constituent units is preferable.

The upper limit of content of a N,N-disubstituted (meth)acrylamide group containing compound in 100 mass % of structural units is 49, 45, 40, 35, 30, 25, 20, 15, 10, 5, 2 mass %. etc. are illustrated, and 45, 40, 35, 30, 25, 20, 15, 10, 5, 2, 1 mass % etc. are illustrated as for a lower limit. In one embodiment, as for content of the N,N- 2-substituted (meth)acrylamide group containing compound in 100 mass % of structural units, 1-49 mass % is preferable.

Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and salts thereof.

The content of the unsaturated carboxylic acid in 100 mol% of the structural unit is not particularly limited, but considering the reaction between the component (b) other than the unsaturated carboxylic acid and the unsaturated carboxylic acid, less than 40 mol% (for example, 30, 20, 19, 15, 10, 5, less than 1 mol%, 0 mol%) is preferable.

60, 50, 40, 30, 20, 10, 5, 1 mass % etc. are illustrated as for the upper limit of content of unsaturated carboxylic acid with respect to 100 mass % of structural units, The lower limit is 50, 40, 30, 20, 10, 5, 1, 0 mass % etc. are illustrated. In one embodiment, as for content of unsaturated carboxylic acid with respect to 100 mass % of structural units, 0.0-60 mass % is preferable.

The unsaturated sulfonic acids include α,β-ethylenically unsaturated sulfonic acids such as vinylsulfonic acid, styrenesulfonic acid and (meth)allylsulfonic acid; (meth)acrylamide t-butylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-(meth)acrylamide-2-hydroxypropanesulfonic acid, 3-sulfopropane (meth)acrylic acid ester, bis -(3-sulfopropyl) itaconic acid ester, these salts, etc. are illustrated.

The content of the unsaturated sulfonic acid in 100 mol% of the structural unit is not particularly limited, but considering the reaction between the component (b) other than the unsaturated sulfonic acid and the unsaturated sulfonic acid, the upper limit of the content of the unsaturated sulfonic acid with respect to 100 mol% of the structural unit is , 40, 30, 20, 19, 15, 10, 5, 1, 0.5, 0.1, 0.05, 0.02 mol%, etc. are exemplified, and the lower limit is 30, 20, 19, 15, 10, 5, 1, 0.5, 0.1, 0.05, 0.02, 0.01, 0 mol%, etc. are illustrated.

As for the upper limit of content of unsaturated sulfonic acid with respect to 100 mass % of structural units, 70, 60, 50, 40, 30, 20, 10, 5, 1, 0.05, 0.02, 0.01 mass % etc. are illustrated, The lower limit is 60, 50, 40, 30, 20, 10, 5, 1, 0.05, 0.02, 0.01, 0 mass %, etc. are illustrated. In one embodiment, as for content of unsaturated sulfonic acid with respect to 100 mass % of structural units, 0-70 mass % is preferable.

The unsaturated phosphoric acid monomer is vinylphosphonic acid, vinyl phosphate, bis((meth)acryloxyethyl)phosphate, diphenyl-2-(meth)acryloyloxyethyl phosphate, dibutyl-2-(meth)acryloyloxy Ethyl phosphate, dioctyl-2-(meth)acryloyloxyethyl phosphate, monomethyl-2-(meth)acryloyloxyethyl phosphate, 3-(meth)acryloxy-2-hydroxypropanephosphoric acid and these salts and the like are exemplified.

The content of the acid group-containing monomer such as unsaturated phosphoric acid in 100 mol% of the structural unit is not particularly limited, but considering the reaction between the component (b) other than unsaturated phosphoric acid and the unsaturated phosphoric acid, 40 mol% based on 100 mol% of the structural unit Less than (for example, 30, 20, 19, 15, 10, 5, less than 1 mol%, 0 mol%) is preferable.

As for the upper limit of the unsaturated phosphoric acid monomer with respect to 100 mass % of structural units, 60, 50, 40, 30, 20, 10, 5, 1 mass % etc. are illustrated, The lower limit is 50, 40, 30, 20, 10, 5 , 1, 0 mass %, etc. are illustrated. In one embodiment, as for content of the unsaturated phosphoric acid monomer with respect to 100 mass % of structural units, 0-60 mass % is preferable.

In one embodiment, the total content of acid group-containing monomers such as unsaturated carboxylic acid, unsaturated sulfonic acid, and unsaturated phosphoric acid in 100 mol% of the structural unit is less than 40 mol% with respect to 100 mol% of the structural unit (for example, 30, 20, 19 , 15, 10, 5, less than 1 mol%, 0 mol%) is preferable.

The upper limit of the total content of acid group-containing monomers such as unsaturated carboxylic acid, unsaturated sulfonic acid, and unsaturated phosphoric acid with respect to 100% by mass of the structural unit is exemplified by 70, 60, 50, 40, 30, 20, 10, 5, 1% by mass, etc. , 60, 50, 40, 30, 20, 10, 5, 1, 0 mass % etc. are illustrated as for a lower limit. In one embodiment, as for the total content of acidic radical containing monomers, such as an unsaturated carboxylic acid, an unsaturated sulfonic acid, and an unsaturated phosphoric acid, with respect to 100 mass % of structural units, 0-70 mass % is preferable.

As for unsaturated carboxylic acid ester, (meth)acrylic acid ester is preferable. As (meth)acrylic acid ester, linear (meth)acrylic acid ester, branched (meth)acrylic acid ester, alicyclic (meth)acrylic acid ester, substituted (meth)acrylic acid ester, etc. are illustrated.

The linear (meth)acrylic acid ester is (meth)methyl acrylate, (meth)ethyl acrylate, (meth)acrylic acid n-propyl, (meth)acrylic acid n-butyl, (meth)acrylic acid n-amyl, (meth)acrylic acid hexyl, (meth)acrylic acid n-octyl, (meth)acrylic acid nonyl, (meth)acrylic acid decyl, etc. are illustrated.

Examples of the branched (meth)acrylic acid ester include (meth)acrylic acid i-propyl, (meth)acrylic acid i-butyl, (meth)acrylic acid i-amyl, (meth)acrylic acid 2-ethylhexyl, and the like.

As alicyclic (meth)acrylic acid ester, (meth)acrylic-acid cyclohexyl etc. are illustrated.

Substituted (meth)acrylic acid esters include glycidyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, ethylene glycol di(meth)acrylate, and ethylene glycol di(meth)acrylate. ) Acrylic acid propylene glycol, tri(meth)acrylic acid trimethylolpropane, tetra(meth)acrylic acid pentaerythritol, hexa(meth)acrylic acid dipentaerythritol, (meth)acrylic acid allyl, di(meth)acrylic acid ethylene, etc. are illustrated.

The content of the unsaturated carboxylic acid ester in 100 mol% of the structural unit is not particularly limited, but flexibility can be imparted to the electrode by using the unsaturated carboxylic acid ester, and is particularly useful when used in a wound-type or cylindrical battery, so that the separator is When manufacturing, it is useful from a viewpoint that the curl of the separator by the fall of the glass transition temperature of (A) component can be suppressed. On the other hand, when the water solubility of (A) component is considered, content of the unsaturated carboxylic acid ester in 100 mol% of structural units is less than 40 mol% with respect to 100 mol% of structural units (for example, 30, 20, 19, 15, 10, 5 , less than 1 mol%, 0 mol%) is preferable.

In addition, the content of the unsaturated carboxylic acid ester with respect to 100 mass % of the structural unit is 90 mass % or less (for example, less than 80, 70, 60, 50, 40, 30, 20, 19, 15, 10, 5, 1 mass %, 0 mass %) is preferable.

The α,β-unsaturated nitrile can be suitably used for the purpose of imparting flexibility to the electrode and the separator. Examples of the α,β-unsaturated nitrile include (meth)acrylonitrile, α-chloro(meth)acrylonitrile, α-ethyl(meth)acrylonitrile, and vinylidene cyanide. Among these, (meth)acrylonitrile is preferable, and acrylonitrile is especially preferable.

The content of α,β-unsaturated nitrile in 100 mol% of the structural unit is not particularly limited, but less than 40 mol% (for example, 30, 20, 19, 15, 10, 5, or less than 1 mol%) based on 100 mol% of the structural unit. . lose

60, 50, 40, 30, 20, 10, 5, 1 mass % etc. are illustrated as for the upper limit of content of alpha, beta- unsaturated nitrile with respect to 100 mass % of structural units, The lower limit is 50, 40, 30, 20, 10, 5, 1, 0 mass % etc. are illustrated. In one embodiment, 0-60 mass % is preferable as content of (alpha), (beta)- unsaturated nitrile with respect to 100 mass % of structural units.

Conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, substituted straight-chain conjugated pentadiene, substituted and side chain conjugated hexadiene and the like are exemplified.

Although content of the conjugated diene in 100 mol% of structural units is not specifically limited, From a viewpoint of the cycling characteristics of a lithium ion battery, less than 10 mol% is preferable in 100 mol% of the said structural units, and 0 mol% is more preferable.

30, 20, 10, 5, 1 mass % etc. are illustrated as an upper limit of content of the conjugated diene with respect to 100 mass % of structural units, and 20, 10, 5, 1, 0 mass % etc. are illustrated as a lower limit. In one embodiment, as for content of the conjugated diene with respect to 100 mass % of structural units, 0-30 mass % is preferable.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene.

Although content of the aromatic vinyl compound in 100 mol% of structural units is not specifically limited, From a viewpoint of the cycling characteristics of a lithium ion battery, less than 10 mol% in 100 mol% of the said structural units is preferable, and 0 mol% is more preferable.

30, 20, 10, 5, 1 mass % etc. are illustrated as an upper limit of content of an aromatic vinyl compound with respect to 100 mass % of structural units, and 20, 10, 5, 1, 0 mass % etc. are illustrated as a lower limit. . In one embodiment, as for content of the aromatic vinyl compound with respect to 100 mass % of structural units, 0-30 mass % is preferable.

Acid group-containing monomers such as unsaturated carboxylic acids, unsaturated sulfonic acids, and unsaturated phosphoric acids, unsaturated carboxylic acid esters, α,β-unsaturated nitriles, conjugated dienes, and aromatic vinyl compounds. Less than 10 mol%, less than 5 mol%, less than 2 mol%, less than 1 mol%, less than 0.1 mol%, less than 0.01 mol%, 0 mol%, etc. Less than, less than 1 mass %, less than 0.5 mass %, less than 0.1 mass %, less than 0.01 mass %, 0 mass % etc. are illustrated.

As for the upper limit of content of (A) component with respect to 100 mass % of slurry, 99.9, 95, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5, 1, 0.5, 0.2 mass % etc. are illustrated and 95, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5, 1, 0.5, 0.2, 0.1 mass % etc. are illustrated as for a minimum. In one embodiment, 0.1-99.9 mass % of (A) component is included with respect to 100 mass % of slurry.

<(A) manufacturing method of component>

(A) A component is various well-known polymerization methods, Preferably it is compoundable by the radical polymerization method. Specifically, a radical polymerization initiator and, if necessary, a chain transfer agent are added to the monomer mixture containing the above components, and the polymerization reaction is preferably carried out at a reaction temperature of 50 to 100° C. while stirring. The reaction time is not particularly limited and is preferably 1 to 10 hours.

Various known radical polymerization initiators are used without particular limitation. The radical polymerization initiator may include persulfates such as potassium persulfate and ammonium persulfate; a redox-based polymerization initiator in which the persulfate and a reducing agent such as sodium hydrogen sulfite are combined; Azo initiators, such as 2,2'- azobis-2- amidinopropane dihydrochloride, etc. are illustrated. Although the usage-amount in particular of a radical polymerization initiator is not restrict|limited, 0.05-5.00 mass % is preferable with respect to 100 mass % of monomer groups which provide (A) component, and 0.1-3.0 mass % is more preferable.

Before radical polymerization and/or when solubilizing the obtained component (A), etc., for the purpose of improving manufacturing stability, pH adjustment of the reaction solution with a general neutralizing agent such as ammonia, organic amine, potassium hydroxide, sodium hydroxide, lithium hydroxide, etc. may do In that case, as for h, 2-11 are preferable. In addition, for the same purpose, EDTA or a salt thereof, which is a metal ion sealing agent, may be used.

(A) When component is equipped with an acidic radical, it can adjust a neutralization rate suitably according to a use, and can use it. Here, 100% of a neutralization rate shows neutralizing with the acidic component contained in (A) component and the alkali of the same mol number. Moreover, 50% of a neutralization rate shows what was neutralized with the alkali of about half mol number with respect to the acidic component contained in (A) component. The neutralization rate is not particularly limited, but after formation of the coating layer or the like, the neutralization rate is preferably 70 to 120%, more preferably 80 to 120%. By setting the degree of neutralization after preparation of the coating layer in the above range, most of the acid is in a neutralized state, and it is preferable because it does not bind to L-ions or the like in the battery to cause a decrease in capacity. Examples of the neutralization salt include L-salt, N-salt, K-salt, ammonium salt, M-salt, C-salt, C-salt, and A-salt.

<Physical properties of component (A)>

(A) Although the weight average molecular weight (Md) of component is not specifically limited, The upper limit of the weight average molecular weight (Mg) is 6 million, 5.5 million, 5 million, 4.5 million, 4 million, 3.5 million, 3 million, 250 10,000, 2 million, 1.5 million, 1 million, 950,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, etc. , lower limit, 5.5 million, 5 million, 4.5 million, 4 million, 3.5 million, 3 million, 2.9 million, 2.5 million, 2 million, 1.5 million, 1 million, 950,000, 900,000, 850,000, 800,000, 75 10,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, etc. are exemplified. In one embodiment, from a viewpoint of the dispersion stability of the slurry for lithium ion batteries, 300,000-6 million are preferable and, as for the weight average molecular weight (Ml) of (A) component, 350,000-6 million are more preferable.

(A) The upper limit of the number average molecular weight (Mn) of component is 6 million, 5.5 million, 5 million, 4.5 million, 4 million, 3.5 million, 3 million, 2.5 million, 2 million, 1.5 million, 1 million, 950,000 , 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 300,000, 200,000, 100,000, 50,000, etc. are exemplified, lower limit, 5.5 million, 5 million, 4.5 million, 4 million, 3.5 million, 3 million, 2.9 million, 2.5 million, 2 million, 1.5 million, 1 million, 950,000, 900,000, 850,000, 800,000, 750,000 , 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 200,000, 100,000, 50,000, 10,000, and the like are exemplified. In one embodiment, as for the number average molecular weight (Mn) of (A) component, 10,000 or more are preferable.

A weight average molecular weight and a number average molecular weight can be calculated|required as a polyacrylic acid conversion value measured in the appropriate solvent by gel permeation chromatography (GPC), for example.

(A) Although the B-type viscosity of component is not specifically limited, The upper limit is 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, 40,000, 30,000, 20,000, 10,000, 9000 , 8000, 7000, 6000, 5000, 4000, 3000, 2000mＰa g, etc. are exemplified, and the lower limit is 90,000, 80,000, 70,000, 60,000, 50,000, 40,000, 30,000, 20,000, 10,000. , 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000mPa·d and the like are exemplified. In one embodiment, as for the range of the B-type viscosity of (A) component, 1000-100,000 mMa·d are preferable. In addition, the B-type viscosity is measured by a B-type viscometer such as "B-type viscometer model MM" manufactured by Toki Sangyo Co., Ltd.

(A) Although the gel fraction of component is not specifically limited, The upper limit of the gel fraction of (A) component is 99.9%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60 % is exemplified, and the lower limit is exemplified by 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, and the like. In one embodiment, 50 % or more is preferable and, as for the gel fraction of (A) component, 55 % or more is more preferable.

In addition, the gel fraction is

Gel fraction (%) = c insoluble matter residue in solution (g)/mass of solid content in solution (g)} x 100

It is a value calculated by

<Water-soluble crosslinking agent (A1): also called (A1) component)

The water-soluble crosslinking agent (A1) of the present invention is an amide group (-C (=) It is preferable to have a functional group excellent in thermal crosslinking reaction with O)NNHR-) and to have the potential to exist stably without crosslinking at room temperature. That is, the water-soluble crosslinking agent (A1) is stably present without crosslinking with the water-soluble poly(meth)acrylamide (A) in the slurry state, and when drying the layer (coating layer) of the slurry after application of the slurry, or by hot pressing It plays a function of thermally crosslinking the water-soluble poly(meth)acrylamide (A). In addition, the above is merely an explanation, and it is not intended that the present invention be limited to the above description.

In one embodiment, the water-soluble crosslinking agent (A1) is used by selecting at least one from the group consisting of formaldehyde, glyoxal, hexamethylenetetramine, urea formaldehyde resin, and methylolmelamine resin.

Content of the water-soluble crosslinking agent (A1) with respect to water-soluble poly(meth)acrylamide (A) is not specifically limited. As for the upper limit of content of a water-soluble crosslinking agent (A1), 3, 2.9, 2, 1, 0.5, 0.1, 0.01, 0.005 mass % etc. are illustrated with respect to 100 mass % of water-soluble poly(meth)acrylamide (A), The lower limit is , 2.9, 2.5, 2, 1, 0.5, 0.1, 0.01, 0.005, 0.001 mass %, etc. are illustrated. In one embodiment, from the viewpoint of springback resistance and the manufacturability of the electrode and/or from the viewpoint of adhesion to the substrate of the ceramic fine particles and the manufacturability of the separator, 0.001 to 3% by mass is preferable, and the effect of the addition of the water-soluble crosslinking agent (A1); And from the viewpoint of preventing the formation of aggregates of the electrode active material particles and/or ceramic fine particles, the content is more preferably 0.01 to 2.9% by mass.

Examples of water include ultrapure water, pure water, distilled water, ion-exchanged water, and tap water.

<Electrode active material (B): also called (B) component>

In one embodiment, the slurry for a lithium ion battery includes an electrode active material (B). As an electrode active material, a negative electrode active material and a positive electrode active material are illustrated.

The negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium, and a suitable material can be appropriately selected according to the type of the intended lithium ion battery, and may be used alone It is good and you may use 2 or more types together. Examples of the negative electrode active material include a material alloyed with lithium such as a carbon material, a silicon material, an oxide containing a lithium atom, a lead compound, a tin compound, an arsenic compound, an antimony compound, and an aluminum compound.

The carbon material is high crystalline carbon graphite (also called graphite, natural graphite, artificial graphite, etc. are exemplified), low crystalline carbon (soft carbon, hard carbon), carbon black (ketjen black), acetylene black , channel black, lamp black, oil furnace black, thermal black, etc.), fullerene, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon fibril, meso Carbon (meso-carbon) microbeads (MCM), pitch-based carbon fibers, and the like are exemplified.

The silicone material is, in addition to silicon, silicon oxide, a silicon _{alloy, SiC, SiO x C y (} 0 <x≤3, 0 <y≤5), Si 3 N 4, Si 2 N 2 O, SiO x (0 A silicon oxide composite represented by <x≤2) (eg, materials described in Japanese Unexamined Patent Publication No. 2004-185810 or 2005-259697, etc.), Japanese Unexamined Patent Publication (Kokai) The silicone material etc. described in Unexamined-Japanese-Patent No. 2004-185810 are illustrated. Moreover, you may use the silicone material described in Japanese Patent No. 5390336 and Japanese Patent No. 5903761.

As for the said silicon oxide, the silicon oxide represented by the compositional formula SOS(0<x<2, Preferably 0.1<x<=1) is preferable.

The silicon alloy is preferably an alloy of silicon and at least one transition metal selected from the group consisting of titanium, zirconium, nickel, copper, iron and molybdenum. Silicon alloys of these transition metals are preferable because they have high electronic conductivity and high strength. The silicon alloy is more preferably a silicon-nickel alloy or a silicon-titanium alloy, and particularly preferably a silicon-titanium alloy. 10 mol% or more is preferable with respect to 100 mol% of the metal elements in the said alloy, and, as for the content rate of the silicon in a silicon alloy, 20-70 mol% is more preferable. The silicon material may be any of single crystal, polycrystal, and amorphous.

When using a silicone material as an electrode active material, you may use together electrode active materials other than a silicone material. Such an electrode active material, the carbon material described above; conductive polymers such as polyacene; A _X B B _Y O _Z (A is an alkali metal or a transition metal, B is at least one selected from transition metals such as cobalt, nickel, aluminum, tin, and manganese, O represents an oxygen atom, and X, Y and Z are Composite metal oxides represented by each of 0.05<X<1.10, 0.85<Y<4.00, and 1.5<Z<5.00), and other metal oxides are exemplified. When a silicon material is used as the electrode active material, it is preferable to use a carbon material together because the volume change due to the insertion and release of lithium is small.

Oxide containing the lithium atom, a ternary nickel-cobalt lithium manganese oxide, lithium-manganese composite oxide (LiMn ₂ O ₄ and the like), lithium-nickel composite oxide (LiNiO ₂ and the like), lithium-cobalt composite oxide (LiCoO _2, etc. ), lithium-iron composite oxide (LiFeO ₂ and the like), lithium-nickel-manganese composite oxide (LiNi _0.5 Mn _0.5 O ₂ and the like), lithium-nickel-cobalt composite oxide (LiNi _0.8 Co _0.2 O ₂ and the like), lithium-transition a metal phosphate compound (LiFePO _4, etc.) and a lithium-transition metal sulfate compound _{(LixFe 2 (SO 4) 3} ), the lithium-titanium composite oxides (lithium titanate: Li ₄ Ti ₅ O _12), lithium such-transition metal composite oxide, and Other conventionally known electrode active materials and the like are exemplified.

From a viewpoint that the effect of this invention is exhibited remarkably, Preferably the carbon material and/or the material alloyed with lithium in an electrode active material becomes like this. Preferably it is 50 mass % or more, More preferably, it is 80 mass % or more, More preferably, it is 90 mass %. % or more, particularly preferably 100 mass%.

The positive electrode active material is roughly divided into an active material containing an inorganic compound and an active material containing an organic compound. Examples of the inorganic compound contained in the positive electrode active material include a transition metal oxide, a composite oxide of lithium and a transition metal, and a transition metal sulfide. Examples of the transition metal include F, C,, N, M, and A. Inorganic compounds used for the positive electrode active _{material, LiCoO 2, LiNiO 2, LiMnO} 2, LiMn 2 O 4, LiFePO 4, LiNi 1/2 Mn 3/2 O 4, LiCo 1/3 Ni 1/3 Mn 1/3 O _{2, Li [Li 0.1 Al 0.1} Mn 1.9] O 4, LiFeVO 4 such as a lithium-containing composite metal oxides; transition metal sulfides such as TS ₂ , TS ₃ , and amorphous MM _{2 ;} The transition metal oxide such as Cu ₂ V ₂ O _3, amorphous _{V 2 O-P 2 O 5} , MoO 3, V 2 O 5, V 6 O 13 and the like. These compounds may be partially element-substituted. Examples of the organic compound contained in the positive electrode active material include conductive polymers such as polyacetylene and poly-p-phenylene. An iron-based oxide lacking in electrical conductivity may be used as an electrode active material covered with a carbon material by the presence of a carbon source material at the time of reduction and firing. Further, these compounds may be partially element-substituted. Among these practical, electrical characteristics, in terms of _{long-life, LiCoO 2, LiNiO 2, LiMnO} 2, LiMn 2 O 4, LiFePO 4, LiNi 1/2 Mn 3/2 O 4, LiCo 1/3 Ni 1/3 Mn _1/3 O ₂ , L G [L A _{0.1 A 0.1 A 0.1} M _{N 1.9} ] O ₄ are preferable.

The shape in particular of an electrode active material is not restrict|limited, Although it may be arbitrary shapes, such as a particulate form and a thin film form, a particulate form is preferable. The average particle diameter of the electrode active material is not particularly limited, but the upper limit thereof is 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 4, 3, 2.9, 2, 1, 0.5, 0.1 μm. and the like are exemplified, and the lower limit is exemplified by 45, 40, 35, 30, 25, 20, 15, 10, 5, 4, 3, 2.9, 2, 1, 0.5, 0.1 μm. In one embodiment, from the viewpoint of forming a uniformly thin coating film, more specifically, if it is 0.1 μm or more, handling property is good, and if it is 50 μm or less, electrode application is easy, so the average particle diameter of the electrode active material is 0.1 to 50 micrometers is preferable, 0.1-45 micrometers is more preferable, 1-10 micrometers is still more preferable, and 5 micrometers is especially preferable.

In the present disclosure, "particle diameter" means the largest distance among the distances between arbitrary two points on the outline of the particle (the same applies hereinafter). In addition, in the present disclosure, the "average particle diameter" is a particle of particles observed in several to several tens of fields of view using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM), unless otherwise specified. The value calculated as the average value of the diameters shall be adopted (the same applies hereinafter).

The upper limit of content of (A) component with respect to 100 mass % of electrode active material (B) in the said slurry is 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3 , 2, 1.5 mass %, etc. are illustrated, and 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1 mass % etc. are illustrated as for a lower limit. In one embodiment, 1-15 mass % of content of (A) component with respect to 100 mass % of electrode active materials (B) is preferable.

In one embodiment, content of silicon or silicon oxide in an electrode active material is 20 mass % or more with respect to 100 mass % of electrode active materials from a viewpoint of raising the battery capacity of a lithium ion battery (for example, 30 mass % or more) , 40 mass % or more, 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % or more, 90 mass % or more, 100 mass %) is preferable.

In one embodiment, a conductive aid may be included in the slurry. Conductive aid is fibrous carbon, such as vapor-grown carbon fiber (VGFC), carbon nanotube (CNF), carbon nanofiber (CNF), carbon black such as graphite particles, acetylene black, Ketjen black, furnace black, average particle diameter of 10 μm or less and fine powders made of Cc, N, A, S or alloys thereof. Although content of a conductive support agent is not specifically limited, 0-10 mass % is preferable with respect to an electrode active material component, and 0.5-6 mass % is more preferable.

<Ceramic fine particles (C): also called (C) component>

In one embodiment, the slurry for a lithium ion battery contains ceramic fine particles (C). Ceramic fine particles are a component coated on the active material side of a porous polyolefin resin substrate, a plastic nonwoven fabric, and an electrode material, and gaps between the ceramic fine particles can form pores. Since ceramic microparticles|fine-particles are provided with nonelectroconductivity, it can be set as insulating, and for this reason, the short circuit in a lithium ion battery can be prevented. Moreover, since ceramic microparticles|fine-particles are equipped with high rigidity normally, the mechanical strength of the separator for lithium ion batteries can be raised. Therefore, even when the stress which tends to shrink|contract to a porous polyolefin resin base material or a plastic nonwoven fabric by heat generate|occur|produces, the separator for lithium ion batteries can withstand the stress. As a result, the occurrence of a short circuit due to shrinkage of the porous polyolefin resin substrate and the plastic nonwoven fabric can be prevented.

By using ceramic microparticles|fine-particles, it is excellent in dispersion stability in water, it is hard to settle in the slurry for lithium ion batteries, and a uniform slurry state can be maintained for a long time. In addition, the use of ceramic fine particles may increase heat resistance. Moreover, ceramic fine particles may be used independently and may use 2 or more types together.

The material of the ceramic fine particles is preferably an electrochemically stable material. From this point of view, ceramic fine particles include oxide particles, nitride particles, covalently bonded crystal particles, poorly soluble ionic crystal particles, clay fine particles, and the like.

Oxide particles are aluminum oxide (alumina), aluminum oxide hydrate (boehmite (AOP), gibbsite ( _AA (O) 3 ), Bakelite, iron oxide, silicon oxide, magnesium oxide (magnesia), magnesium hydroxide, calcium oxide, titanium oxide (titania), BTBO ₃ , HO, alumina-silica composite oxide, and the like.

Examples of the nitride particles include aluminum nitride, silicon nitride, and boron nitride.

Examples of the covalent crystal grains include silicon and diamond.

Examples of the sparingly soluble ionic crystal particles include barium sulfate, calcium fluoride, and barium fluoride.

Examples of the clay fine particles include silica, talc, and clay fine particles such as montmorillonite.

Among these, from the viewpoint of low water absorption and excellent heat resistance, boehmite, alumina, magnesium oxide and barium sulfate are preferable, and boehmite is more preferable.

The upper limit of the average particle diameter of the ceramic fine particles is exemplified by 30, 25, 20, 15, 10, 5, 1, 0.5, 0.1, 0.05 μm, and the like, and the lower limit is 25, 20, 15, 10, 5, 1, 0.5, 0.1, 0.05, 0.01 micrometer, etc. are illustrated. In one embodiment, the average particle diameter of the ceramic fine particles is preferably 0.01 to 30 µm.

The upper limit of content of the ceramic microparticles|fine-particles (C) with respect to 100 mass % of the said slurry is 99.9, 95, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5, 1, 0.5, 0.2 mass %, etc. This is illustrated, and as for a lower limit, 95, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5, 1, 0.5, 0.2, 0.1 mass % etc. are illustrated. In one embodiment, 0.1-99.9 mass % of ceramic microparticles|fine-particles (C) are included with respect to 100 mass % of slurry.

The upper limit of content of (A) component with respect to 100 mass % of ceramic fine particles (C) in the said slurry is 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3 , 2, 1.5 mass %, etc. are illustrated, and 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1 mass % etc. are illustrated as for a lower limit. In one embodiment, 1-15 mass % is preferable, as for content of (A) component with respect to 100 mass % of ceramic fine particles (C), 1.5-14 mass % is more preferable, 2-12 mass % is more preferably. By setting it as such content, the lithium ion battery separator which is more excellent in adhesiveness, and also has a small resistance and further excellent in charge/discharge characteristics can be manufactured.

<Slurry viscosity adjusting solvent>

Although there is no restriction|limiting in particular as a slurry viscosity adjusting solvent, The non-aqueous medium provided with the standard boiling point of 80-350 degreeC may also be included. The slurry viscosity adjusting solvent may be used independently and may use 2 or more types together. The slurry viscosity adjusting solvent may be an amide solvent such as N-methylpyrrolidone, dimethylformamide or N,N-dimethylacetamide; hydrocarbon solvents such as toluene, xylene, n-dodecane, and tetralin; alcohol solvents such as methanol, ethanol, 2-propanol, isopropyl alcohol, 2-ethyl-1-hexanol, 1-nonanol, and lauryl alcohol; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, porone, acetophenone, and isophorone; ether solvents such as dioxane and tetrahydrofuran (THF); ester solvents such as benzyl acetate, isopentyl butyrate, methyl lactate, ethyl lactate, and butyl lactate; amine solvents such as o-toluidine, m-toluidine and p-toluidine; lactones such as γ-butyrolactone and δ-butyrolactone; sulfoxide/sulfone solvents such as dimethyl sulfoxide and sulfolane; water and the like are exemplified. Among them, N-methylpyrrolidone is preferable from the viewpoint of coating workability. Although content of the said non-aqueous medium is not specifically limited, 0-10 mass % is preferable with respect to 100 mass % of the said slurry.

<Additives>

The thermally crosslinkable lithium ion battery slurry contains as an additive that does not correspond to any of (A) component, (A1) component, (B) component, (C) component, water, conductive aid, and slurry viscosity adjusting solvent. can do.

As an additive, a dispersing agent, a leveling agent, antioxidant, a thickener, a dispersion (emulsion), a crosslinking agent, etc. are illustrated.

As for content of an additive, 0-5 mass %, less than 1 mass %, less than 0.1 mass %, less than 0.01 mass %, 0 mass % etc. are illustrated with respect to 100 mass % of (A) component.

As for content of an additive, 0-5 mass %, less than 1 mass %, less than 0.1 mass %, less than 0.01 mass %, 0 mass % etc. are illustrated with respect to 100 mass % of (A1) component.

As for content of an additive, 0-5 mass %, less than 1 mass %, less than 0.1 mass %, less than 0.01 mass %, 0 mass % etc. are illustrated with respect to 100 mass % of (B)component or (C)component.

As for content of an additive, 0-5 mass %, less than 1 mass %, less than 0.1 mass %, less than 0.01 mass %, 0 mass % etc. are illustrated with respect to 100 mass % of the said slurry aqueous solution.

Examples of the dispersant include an anionic compound, a cationic compound, a nonionic compound, and a high molecular compound.

Surfactants, such as alkyl type surfactant, silicone type surfactant, fluorine type surfactant, and metallic surfactant, etc. are illustrated as a leveling agent. By using a surfactant, splashing generated during application can be prevented, and the smoothness of the layer (coating layer) of the slurry can be improved.

Examples of the antioxidant include a phenol compound, a hydroquinone compound, an organophosphorus compound, a sulfur compound, a phenylenediamine compound, and a polymer type phenol compound. The polymeric phenolic compound is a polymer having a phenolic structure in its molecule. 200-1000 are preferable and, as for the weight average molecular weight of a polymer type phenolic compound, 600-700 are more preferable.

A thickener, Cellulose polymers, such as carboxymethylcellulose, methylcellulose, and hydroxypropyl cellulose, and these ammonium salts and alkali metal salts; (modified) poly(meth)acrylic acid and ammonium salts and alkali metal salts thereof; (modified) polyvinyl alcohol, such as a copolymer of polyvinyl alcohol, acrylic acid or acrylate and vinyl alcohol, and a copolymer of maleic anhydride or maleic acid or fumaric acid and vinyl alcohol; Polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, modified polyacrylic acid, oxidized starch, phosphoric acid starch, casein, various modified starches, acrylonitrile-butadiene copolymer hydride, etc. are illustrated.

The dispersion (emulsion), styrene-butadiene-based copolymer latex, polystyrene-based polymer latex, polybutadiene-based polymer latex, acrylonitrile-butadiene-based copolymer latex, polyurethane-based polymer latex, polymethylmethacrylate-based polymer latex, Methyl methacrylate-butadiene-based copolymer latex, polyacrylate-based polymer latex, vinyl chloride-based polymer latex, vinyl acetate-based polymer emulsion, vinyl acetate-ethylene-based copolymer emulsion, polyethylene emulsion, carboxy-modified styrene-butadiene copolymer resin emulsion, Acrylic resin emulsion, polyethylene, polypropylene, polyethylene terephthalate, polyamide (PA), polyimide (PA), polyamide imide (PA), aromatic polyamide, alginic acid and its salts, polyvinylidene fluoride (PSD), poly Tetrafluoroethylene (PTF), tetrafluoroethylene-hexafluoropropylene copolymer (FPI), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (EFF) ) and the like are exemplified.

The crosslinking agent is formaldehyde, glyoxal, hexamethylenetetramine, urea formaldehyde resin, methylolmelamine resin, carbodiimide compound, polyfunctional epoxy compound, oxazoline compound, polyfunctional hydrazide compound, isocyanate compound, melamine compound, Urea compounds and mixtures thereof are exemplified.

Although binders other than (A) component may be contained in the said slurry for lithium ion batteries, content of (A) component in all binders is 90 mass % or more (for example, 91, 95, 98, 99 mass %) above, 100 mass %) is preferable.

Moreover, binders other than (A) component may be used individually or may use 2 or more types together, Fluorine resin (polyvinylidene fluoride, polytetrafluoroethylene, etc.), polyolefin (polyethylene, polypropylene, etc.), an unsaturated bond Polymers containing This is exemplified.

The thermally crosslinkable lithium ion battery slurry is a thermally crosslinkable lithium ion battery electrode slurry, thermally crosslinkable lithium ion battery negative electrode slurry, thermally crosslinkable lithium ion battery positive electrode slurry, and thermally crosslinkable lithium ion battery separator slurry. can be used

[3. Manufacturing method of slurry for lithium ion battery]

The present disclosure provides a method for preparing the slurry for a lithium ion battery, including the step of adding the water-soluble crosslinking agent (A1) to an aqueous solution containing a water-soluble poly(meth)acrylamide (A). Moreover, the above-mentioned thing etc. are illustrated as (A) component etc. described in this item.

In one embodiment, the process of obtaining a slurry solution includes the process of adding and mixing a water-soluble poly(meth)acrylamide (A), a water-soluble crosslinking agent (A1), water, and an electrode active material or ceramic microparticles|fine-particles. The method of adding the water-soluble crosslinking agent (A1) is

Mix after preparation of water-soluble poly(meth)acrylamide (A) aqueous solution

· After dispersing the electrode active material or ceramic fine particles in a water-soluble poly(meth)acrylamide (A) aqueous solution, mix (also called post-addition)

method etc. are mentioned, and from a viewpoint of stability, the direction of post-addition is preferable.

As the mixing means of the slurry, a ball mill, a sand mill, a pigment disperser, a grinder (mortar machine), an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer, and the like are exemplified.

[4.Lithium-ion battery electrode]

The present disclosure provides an electrode for a lithium ion battery in which a dried product of the slurry for a lithium ion battery obtained by applying the slurry for a thermal crosslinking type lithium ion battery to a current collector and performing a thermal crosslinking reaction is provided on the surface of the current collector.

As the current collector, various known ones may be used without particular limitation. The material of the current collector is not particularly limited, and examples thereof include metal materials such as copper, iron, aluminum, nickel, stainless steel, and nickel-plated steel, and carbon materials such as carbon cloth and carbon paper. The shape of the current collector is also not particularly limited, and in the case of a metal material, a metal foil, a metal column, a metal coil, a metal plate, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder, etc. are illustrated. Among them, when an electrode active material is used for a negative electrode, copper foil as a current collector is currently used in industrial products, so it is preferable.

The application means is not particularly limited, and conventionally known coating devices such as a comma coater, a gravure coater, a micro gravure coater, a die coater, and a bar coater are exemplified.

The drying means is not particularly limited, either, and the temperature is preferably 60 to 200°C, more preferably 100 to 195°C. The atmosphere may be dry air or an inert atmosphere.

Although the thickness of an electrode (cured coating film) is not specifically limited, 5-300 micrometers is preferable and 10-250 micrometers is more preferable. By setting it as the above range, a function of occluding and releasing sufficient Lg for a high-density current value can be easily obtained.

The said electrode for lithium ion batteries can be used as a positive electrode for lithium ion batteries, and a negative electrode for lithium ion batteries.

[5. Lithium-ion battery separator]

The present disclosure provides a dried product of the slurry for a thermally crosslinkable lithium ion battery obtained by applying the slurry for a thermally crosslinkable lithium ion battery to a porous polyolefin resin substrate or plastic nonwoven fabric and drying, on the surface of a porous polyolefin resin substrate or plastic nonwoven fabric A separator for lithium ion batteries is provided.

The said slurry for lithium ion batteries may be apply|coated only to one surface of a base material, and may be apply|coated to both surfaces.

(Porous polyolefin resin substrate)

In one embodiment, the substrate is preferably a porous membrane having ion conductivity without electron conductivity, high resistance to organic solvents, and a fine pore diameter. As such a porous membrane, there is a porous polyolefin resin substrate. A porous polyolefin resin base material is a microporous film which contains resin, such as polyolefin and their mixture or copolymer, as a main component. The porous polyolefin resin substrate has excellent applicability of the coating solution when a polymer layer is obtained through the coating process, and the film thickness of the separator is made thinner to increase the active material ratio in the lithium ion battery, and from the viewpoint of increasing the capacity per volume. desirable. Moreover, "included as a main component" means containing more than 50 mass %, Preferably it is 75 mass % or more, More preferably, it is 85 mass % or more, More preferably, it is 90 mass % or more, More preferably, 95 mass % or more, Especially preferably 98 mass % or more is included, and 100 mass % may be sufficient.

In one embodiment, although content of the polyolefin resin in a porous polyolefin resin base material is not specifically limited, From a viewpoint, such as shutdown performance at the time of using as a separator for lithium ion batteries, in a porous polyolefin resin base material The content of the polyolefin resin is preferably 50% by mass or more and 100% by mass or less of all the components constituting the substrate, more preferably 60% by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less more preferably.

Although polyolefin resin is not specifically limited, Polyolefin resin used for extrusion, injection, inflation, blow molding, etc. may be sufficient, You may use individually, and may use 2 or more types together. Examples of the polyolefin resin include homopolymers, copolymers, and multistage polymers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene. The polymerization catalyst used in the production of these polyolefin resins is also not particularly limited, and examples thereof include a Ziegler-Natta catalyst, a Phillips catalyst and a metallocene catalyst.

Since the polyolefin resin used as the material of the porous polyolefin resin base material has a low melting point and high strength, a resin containing particularly high-density polyethylene as a main component is preferable. Further, from the viewpoint of improving the heat resistance of the polyolefin porous substrate, it is more preferable to use together polypropylene and a porous polyolefin resin substrate containing a polyolefin resin other than polypropylene.

Here, the three-dimensional structure of the polypropylene is not limited, and any of isotactic polypropylene, syndiotactic PP, and atactic PP may be used.

Although the ratio of polypropylene with respect to the polyolefin whole amount contained in polyolefin resin composition is not specifically limited, From a viewpoint of coexistence of heat resistance and a favorable shutdown function, 1-35 mass % is preferable, 3-20 mass % is more preferable, and 4-10 mass % is still more preferable.

In this case, the polyolefin resin other than polypropylene is not limited, For example, a homopolymer or copolymer of olefin hydrocarbons such as ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. is exemplified Specific examples of polyolefin resins other than polypropylene include polyethylene, polybutene, and ethylene-propylene random copolymer.

Polyolefin resins other than polypropylene from the viewpoint of shutdown properties in which the pores of the polyolefin porous substrate are blocked by thermal melting, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, etc. polyethylene It is preferable to use Among these, from the viewpoint of strength, ^{polyethylene having a density of 0.93 g/cm 3} or more as measured according to JIS K 7112 is more preferable.

The porous polyolefin resin substrate may contain a filler or a fiber compound for the purpose of controlling strength, hardness, and thermal shrinkage. In addition, for the purpose of improving the adhesion with the adhesive layer or lowering the surface tension with the electrolyte to improve the impregnability of the solution, the surface of the porous polyolefin resin substrate is coated in advance with a low molecular compound or a high molecular compound, or Electron beam treatment such as ultraviolet rays or plasma treatment such as corona discharge and plasma gas may be performed. In particular, in terms of high impregnation property of the electrolyte and easy to obtain adhesion with the coating layer obtained by applying and drying the slurry on a substrate, coating treatment with a polymer compound containing polar groups such as carboxylic acid groups, hydroxyl groups and sulfonic acid groups desirable.

Although the thickness of a porous polyolefin resin base material is not specifically limited, 2 micrometers or more are preferable, 5 micrometers or more are more preferable, 100 micrometers or less are preferable, 60 micrometers or less are more preferable, 50 micrometers or less are still more preferable. It is preferable to adjust this thickness to 2 micrometers or more from a viewpoint of improving mechanical strength. On the other hand, it is preferable to adjust this film thickness to 100 micrometers or less, since the occupied volume of the separator in a battery decreases, and since it tends to become advantageous in the point of high capacity|capacitance of a battery, it is preferable.

(plastic nonwoven fabric)

In one embodiment, the average fiber diameter of the plastic nonwoven fabric used for the separator for lithium ion batteries is preferably 1 to 15 μm, more preferably 1 to 10 μm, from the viewpoint of adhesion to the nonwoven fabric and separator thickness. .

In one embodiment, 1-20 micrometers is preferable, as for the average pore diameter of the said plastic nonwoven fabric, 3-20 micrometers is more preferable, 5-20 micrometers is still more preferable. If the average pore diameter is less than 1 µm, the internal resistance becomes large and the output characteristics deteriorate. On the other hand, if the average pore diameter is 20 µm or more, an internal short circuit may occur at the time of lithium dendrite formation.

In the present disclosure, the pore diameter means an interval between the synthetic fibers forming the plastic nonwoven fabric. In addition, the average fiber diameter means the average value of the fiber diameters of 20 randomly selected fibers by measuring the fiber diameter of a fiber from a scanning electron micrograph. Similarly, the average pore diameter means the average value of the pore diameters of 20 randomly selected fibers by measuring the pore diameters of the fibers from the scanning electron micrograph.

The nonwoven fabric is preferably composed of only synthetic fibers having an average fiber diameter of 1 to 10 μm and an average pore diameter of 1 to 20 μm, but if necessary, such as when the need to reduce the thickness of the separator is not very high A synthetic fiber having an average fiber diameter and a pore diameter different from the above may be used in combination. In addition, from the same viewpoint, fibers other than synthetic fibers may be appropriately used in combination. In the case of using these fibers (synthetic resin fibers or fibers other than synthetic fibers whose average fiber diameter and average pore diameter are outside the ranges specified herein), the content thereof is 30% by mass or less from the viewpoint of securing the strength of the nonwoven fabric. It is preferable, and 20 mass % or less is more preferable, and 10 mass % or less is still more preferable.

A synthetic resin which is the material of the synthetic resin fibers, polyolefin (polyolefin) resins, polyester (polyester) resin, polyvinyl acetate (polyvinyl acetate) resin, ethylene-vinyl acetate copolymer (ethylene-vinyl acetate copolymer) resin, poly amides (polyamide) resin, an acrylic (acrylic) resin, PVC (polyvinyl chloride) based resin, polyvinylidene chloride (polyvinylidene chloride) resin, polyvinyl ethers (polyvinyl ether) resins, polyvinyl ketone (polyvinylketone ) based resin, polyether-based resin, a polyvinyl alcohol (polyvinyl alcohol) type resin, a diene (diene) based resin, a polyurethane (polyurethane) resin, phenol (phenol) resin, melamine (melamine) resin, furan ( furan) based resin, urea resin, aniline (aniline) based resin, an unsaturated polyester (unsaturated polyester) resin, an alkyd (alkyd) resin, a fluorine (fluorocarbon) based resin, silicon (silicone) resin, polyamide-imide ( polyamide imide) resins, polyphenylene renseol feed (polyphenylene sulfide) resin, polyimide (polyimide) resin, polycarbonate (polycarbonate) resin, polyazo-methine (polyazomethine) based resins, polyester amide (polyesteramide) resin, polyetheretherketone (polyetheretherketone) resin, poly -p- phenylene benzo-bis-oxazol (poly-p-phenylenebenzobisoxazole) resin, polybenzimidazole (polybenzimidazole) based resin, an ethylene-vinyl alcohol copolymer (ethylene-vinylalcohol copolymer )-based resins and the like are exemplified. Among them, polyester-based resins, acrylonitrile-based resins, and polyolefin-based resins are preferable in order to improve adhesion to ceramic fine particles. In addition, when a polyester-based resin, an acrylic resin, or a polyamide-based resin is used, the heat resistance of the separator may be improved.

Polyester-based resins, polyethylene terephthalate (polyethylene terephthalate, PET) system, polybutylene terephthalate (polybuthylene terephthalate, PBT) based, PTT (polytrimethylene terephthalate, PPT) based, polyethylene naphthalate (polyethylene naphthalate, the PEN) based, polybutylene phthalate (polybuthylene naphthalate), polyethylene naphthalate resin, such as hydrogen or (polyethylene isonaphthalate) based, wholly aromatic polyester (fully aromatic polyester) system and the like. Derivatives of these resins can also be used. Among these resins, in order to improve heat resistance, electrolyte resistance, and adhesiveness with ceramic fine particles, polyethylene terephthalate-based resins are preferable.

The acrylonitrile-based resin is composed of a polymer of 100% acrylonitrile, and copolymerization of (meth)acrylic acid derivatives such as acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester with respect to acrylonitrile, vinyl acetate, etc. water and the like are exemplified.

Examples of the polyolefin-based resin include polypropylene, polyethylene, polymethylpentene, ethylene-vinyl alcohol copolymer, and olefin-based copolymer. From the viewpoint of heat resistance, the polyolefin-based resin is preferably polypropylene, polymethylpentene, ethylene-vinyl alcohol copolymer, or olefin-based copolymer.

The polyamide-based resin is an aliphatic polyamide such as nylon, poly-p-phenylene terephthalamide, poly-p-phenylene terephthalamide-3,4-diphenyl ether terephthalamide, and poly-m-phenylene isophthalamide. Wholly aromatic polyamides, such as amide|amido, the semi-aromatic polyamide etc. which have an aliphatic chain in a part of the main chain in aromatic polyamide are illustrated. The wholly aromatic polyamide may be either a para-type or a meta-type.

The synthetic resin fiber may be a fiber (single fiber) composed of a single resin, or a fiber (composite fiber) composed of two or more types of resin. Examples of the composite fiber include a sheath-core type, an eccentric type, a side-by-side type, a sea-island type, an orange type, and a multi-bimetal type.

In addition, fibers other than synthetic resin fibers that can be used in combination with synthetic resin fibers include short fibers or fibrillates of solvent-spun cellulose or regenerated cellulose, natural cellulose fibers, pulps and fibrillates of natural cellulose fibers, inorganic fibers and the like are exemplified.

The thickness of the plastic nonwoven fabric is preferably 5 to 25 µm, more preferably 5 to 15 µm, from the viewpoint of making the thickness thin and obtaining a separator with little internal resistance.

The method of applying the lithium ion battery slurry to the substrate is not particularly limited, but various coating methods such as blade, rod, reverse roll, lip, die, curtain, air knife, flexographic, screen, offset, Various printing methods such as gravure and inkjet, a transfer method such as roll transfer and film transfer, and a method of scraping off the coating liquid on the non-coated surface side after a pulling method such as dipping are exemplified.

In the layer (coating layer) of the slurry for lithium ion batteries, by crosslinking the slurry for lithium ion batteries containing component (A) and component (C), the layer of the slurry for lithium ion batteries can be formed. The crosslinking reaction can proceed, for example, when drying the slurry for lithium ion batteries. Specific drying methods include drying by wind such as warm air, hot air, and low humidity; vacuum drying; The drying method by irradiation of infrared rays, far infrared rays, an electron beam, etc., etc. are illustrated.

The lower limit of the temperature during drying is preferably 40°C or higher, more preferably 45°C or higher, particularly preferably 50°C or higher, from the viewpoint of efficiently removing the solvent and low molecular weight compound from the composition for a porous membrane, The upper limit is preferably 90°C or less, more preferably 80°C or less, from the viewpoint of suppressing deformation of the substrate due to heat.

The lower limit of the drying time is preferably 5 seconds or more, more preferably 10 seconds or more, particularly preferably 15 seconds or more, and the upper limit is preferably 3 minutes or less, more preferably 2 minutes or less. Since the solvent can be fully removed from the composition for porous membranes by making the drying time more than the lower limit of the said range, the output characteristic of a battery can be improved. Moreover, manufacturing efficiency can be improved by setting it as below an upper limit.

The manufacturing method of the separator for lithium ion batteries may include any process other than the above. The manufacturing method of the separator for lithium ion batteries may include a pressure treatment process of the layer (coating layer) of the lithium ion battery slurry by a press such as a mold press and a roll press. By performing a pressurization process, the binding property of a base material and the layer of the slurry for lithium ion batteries can be improved. However, from a viewpoint of maintaining the porosity of the layer of the slurry for lithium ion batteries in a preferable range, it is preferable to control appropriately so that the pressure and pressurization time do not become large too much. In addition, in order to remove residual moisture, the manufacturing method of the separator for a lithium ion battery may include drying in a vacuum or in a dry room.

[6. Lithium-ion battery separator/electrode laminate]

The present disclosure provides a separator/electrode laminate for a lithium ion battery that is a dried product of the slurry for a thermally crosslinkable lithium ion battery obtained by applying the slurry for a thermally crosslinkable lithium ion battery to an electrode and drying it.

Various well-known electrodes can be used for the electrode used when manufacturing the separator/electrode laminated body for lithium ion batteries, The electrode provided by this disclosure may be sufficient, and it may not be the electrode provided by this disclosure.

The manufacturing method of the separator/electrode laminate for a lithium ion battery includes the steps of applying, drying, and pressing a slurry containing an electrode material such as the slurry for a lithium ion battery to a current collector; Not on the side, but on the electrode active material side), a method including a step of applying and drying the slurry for a lithium ion battery is exemplified. The coating method, drying method, conditions, etc. are exemplified above.

[7.Lithium-ion battery]

The present disclosure provides a lithium ion battery including the electrode for the lithium ion battery. In addition, the present disclosure provides a lithium ion battery comprising the separator for a lithium ion battery and/or the separator/electrode laminate for a lithium ion battery. The battery also includes an electrolyte and a packaging material, which are not particularly limited.

(electrolyte)

Examples of the electrolytic solution include a non-aqueous electrolytic solution in which a supporting electrolyte is dissolved in a non-aqueous solvent. Moreover, the said non-aqueous electrolyte solution may contain the film-forming agent.

As the non-aqueous solvent, various well-known solvents can be used without particular limitation, and may be used alone or in combination of two or more. Examples of the non-aqueous solvent include chain carbonate solvents such as diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate; cyclic carbonate solvents such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain ether solvents such as 1,2-dimethoxyethane; cyclic ether solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane; chain ester solvents such as methyl formate, methyl acetate, and methyl propionate; cyclic ester solvents such as γ-butyrolactone and γ-valerolactone; acetonitrile and the like are exemplified. Among these, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable.

As the supporting electrolyte, a lithium salt is used. Various well-known things in particular can be used for a lithium salt without a restriction|limiting, It may be used independently or may use 2 or more types together. Supporting _{electrolytes, LiPF 6, LiAsF 6, LiBF} 4, LiSbF 6, LiAlCl 4, LiClO 4, CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi, (CF _{3 SOS 2} ) ₂ N L L, (C ₂ F ₅ S _{O 2} ) N L L, and the like are exemplified. _{Among them, LPF 6} , LPF ₄ , C F ₃ S S _{O 3} L which shows a high degree of dissociation which is easy to dissolve in a solvent is preferable. Since the lithium ion conductivity increases as the supporting electrolyte having a high degree of dissociation is used, the lithium ion conductivity can be adjusted according to the type of the supporting electrolyte.

Various well-known things in particular can be used for a film forming agent without restriction|limiting, It may be used independently or may use 2 or more types together. The film forming agent may be a carbonate compound such as vinylene carbonate, vinyl ethylene carbonate, vinyl ethyl carbonate, methylphenyl carbonate, fluoroethylene carbonate, or difluoroethylene carbonate; alkene sulfides such as ethylene sulfide and propylene sulfide; sultone compounds such as 1,3-propane sultone and 1,4-butane sultone; Acid anhydrides, such as maleic anhydride and succinic anhydride, etc. are illustrated. Although content of the film forming agent in electrolyte solution is not specifically limited, 10 mass % or less, 8 mass % or less, 5 mass % or less, and 2 mass % or less are preferable in this order. When the content is 10% by mass or less, the advantages of the film forming agent, such as suppression of initial irreversible capacity and improvement of low-temperature characteristics and rate characteristics, can be easily obtained.

The shape of the lithium ion battery is not particularly limited. Examples of the lithium ion battery include a cylinder type in which a sheet electrode and a separator are spirally formed, a cylinder type in an inside-out structure in which a pellet electrode and a separator are combined, and a coin type in which a pellet electrode and a separator are laminated. In addition, by putting the battery of these types in an arbitrary external case, it can be used as arbitrary shapes, such as a coin shape, a cylinder shape, and a rectangle.

The manufacturing method of the lithium ion battery is not particularly limited, and may be assembled in an appropriate order according to the structure of the battery. As for the manufacturing method of a lithium ion battery, the method etc. which were described in Unexamined-Japanese-Patent No. 2013-089437 are illustrated. A battery can be manufactured by placing a negative electrode on an exterior case, providing an electrolyte solution and a separator thereon, placing a positive electrode facing the negative electrode, and fixing it with a gasket or sealing plate.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples. In addition, in the following, "part" and "%" show a mass part and mass %, respectively, unless there is special explanation.

1. (A) Manufacture of component

Preparation Example 1

In a reactor equipped with a stirrer, thermometer, reflux cooling tube, and nitrogen gas inlet tube, 1095 g of ion-exchanged water, 400 g (2.81 mM) of 50% acrylamide aqueous solution, sodium methallyl sulfonate (2-methyl-2-propene-1) -Sodium sulfonate) 0.22g (0.0014mf) was added, and after removing oxygen in the reaction system through nitrogen gas, the temperature was raised to 50°C. 2.0 g of 2,2'-azobis-2-amidinopropane dihydrochloride (NIPPOH CHEMICALS CO., LTD., product name 「NFC-32」) and 50 g of ion-exchanged water were added thereto, 80 The temperature was raised to °C, and the reaction was carried out for 3 hours to obtain an aqueous solution containing polyacrylamide.

Preparation Example 2

In a reactor equipped with a stirrer, thermometer, reflux cooling tube and nitrogen gas inlet tube, 1428 g of ion-exchanged water, 400 g (2.81 mM) of 50% aqueous acrylamide solution, 63.5 g (0.70 mM of 80% aqueous solution of acrylic acid), sodium methallyl sulfonate 0.56 g (0.0035 mf) was added. After removing oxygen in the reaction system through gas, the temperature was raised to 50°C. 2.5 g of 2,2'-azobis-2-amidinopropane dihydrochloride (product name of Nippo Chemical Co., Ltd. product name "NFC-32") and 50 g of ion-exchanged water were added thereto, the temperature was raised to 80°C, and the reaction was performed for 3.0 hours. , an aqueous solution containing a polyacrylamide-acrylic acid copolymer was obtained.

Production Examples 3 to 11

In Production Example 2, an aqueous solution containing water-soluble poly(meth)acrylamide was prepared in the same manner as in Production Example 2 except that the monomer composition and the amount of the initiator were changed to those shown in Table 1.

Comparative Preparation Example 1

In a reactor equipped with a stirrer, a thermometer, a reflux cooling tube, and a nitrogen gas inlet tube, 2.5 g of sodium dodecylbenzenesulfonate as an emulsifier, 944 g of ion-exchanged water and 1.9 g of potassium persulfate as a polymerization initiator were placed, and 50% acrylamide aqueous solution 14 g, 21 g of acrylamide t-butylsulfonic acid, 576 g of butyl acrylate, and 30 g of N-methylolacrylamide were added dropwise at 50°C over 1 hour to perform polymerization. After superposing|polymerizing at the same temperature for 2 hours, it cooled to 25 degreeC, and obtained the water dispersion containing particulate-form polyacrylamide-acrylic acid ester.

・AM: acrylamide (Mitsubishi Chemical Corporation “50% acrylamide”)

・ATB: acrylamide t-butylsulfonic acid (“ATB” manufactured by TOAGOSEI CO., LTD.)

・NMF:N-methylolacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI))

・DMAG:N,N-dimethylacrylamide (manufactured by Tokyo Kasei Industrial Co., Ltd.)

・AAA: acrylic acid (“80% acrylic acid” manufactured by Osaka Organic Chemical Industry Ltd.)

・ANP: Acrylonitrile (“Acrylonitrile” manufactured by Mitsubishi Chemical Co., Ltd.)

·HEMMA: 2-hydroxyethyl methacrylate (manufactured by Tokyo Kasei Industrial Co., Ltd.)

·BAA: butyl acrylate (product of Wako Pure Chemical Industries, Ltd.)

・SMS: Sodium methallylsulfonate

The physical property of (A) component described in a table|surface was measured as follows.

B-shaped viscosity

The viscosity of each binder aqueous solution was measured at 25°C under the following conditions using a B-type viscometer (product name "B-type viscometer model MM" manufactured by Toki Industries Co., Ltd.).

For viscosity of 100,000 to 20,000mP·d: Nd. 4 rotors are used, the number of rotations is 6 gpm, and the viscosity is less than 20,000mp·d: Np. 3 rotors are used, and the number of revolutions is 6 gm.

weight average molecular weight

The weight average molecular weight was determined as a converted value of polyacrylic acid measured by gel permeation chromatography (GPC) in a 0.2 M phosphate buffer/acetonitrile solution (90/10, pH 8.0). As the GPS device, HLC-8220 (manufactured by Tosoh Corporation) was used, and as the column, SBS-806M-HHS (manufactured by SHS) was used.

Combination Example 1

To 100 parts by mass of the water-soluble poly(meth)acrylamide (A) obtained in Production Example 1, 1 part by mass of a 37% aqueous formaldehyde solution (hereinafter also referred to as formalin) in terms of solid content was added, and mixed at 25° C. for 0.5 hours, A uniform water-soluble battery binder was obtained. The gel fraction of the obtained binder for water-soluble batteries was measured in the following procedure.

<Gel fraction>

Solid resin was obtained after drying the water-soluble battery binder which mix|blended the water-soluble crosslinking agent (A1) with the water-soluble poly(meth)acrylamide (A) at 120 degreeC for 4 hours with a tail wind dryer. After accurately measuring the mass of the solid resin and immersing it in water under stirring conditions for 3 hours, it was filtered under reduced pressure with a filter paper of KIRIYAMA RHOTO (NV 50B manufactured by Kiriyama Glass Works Co.). After that, the filtrate was dried at 120° C. for 3 hours, the mass of the insoluble residue was accurately measured, and the gel fraction of the resin after thermal crosslinking of the water-soluble battery binder was calculated from the following formula.

Gel fraction (%) = b insoluble residue (g)/mass of solid resin (g)} x 100

Formulation Examples 2 to 12, Comparative Formulation Examples 1 to 3

In Formulation Example 1, the gel fraction of the obtained resin was measured in the same manner as in Formulation Example 1 except that the type and amount of the water-soluble crosslinking agent (A1) were changed to those shown in Table 2 and numerical values.

Formalin: 37% formaldehyde aqueous solution

・Glyoxal: 40% glyoxal solution (product of Wako Junyaku Industrial Co., Ltd.)

· Hexamethylenetetramine (manufactured by Wako Pure Chemical Industries, Ltd.)

·Methylolmelamine resin

・Urea formaldehyde resin

Example 1-1: Electrode evaluation

(1) Preparation of slurry for lithium ion battery electrodes

Using a commercially available revolving mixer (product name "Awatori Rentaro", manufactured by THINKY CORPORATION), in a container dedicated to the mixer, poly (meth) acrylamide (A) obtained in Formulation Example 1 and 7 parts by mass of an aqueous binder solution containing a water-soluble crosslinking agent (A1) in terms of solid content, 50 parts by mass of silicon particles having a D50 of 5 μm, and natural graphite (Ito Graphite Co., Ltd. Product name "K-5F") 50 mass parts was mixed. Ion-exchanged water was added thereto so that the solid content concentration was 40%, and the container was set in the mixer. Then, after kneading for 10 minutes at 2000 nm, it defoamed for 1 minute and obtained the slurry for electrodes.

(2) Preparation of electrode for lithium ion battery

On the surface of the current collector made of copper foil, the lithium ion battery slurry is uniformly applied by a doctor blade method so that the film thickness after drying becomes 25 μm, dried at 60° C. for 30 minutes, and then at 150° C. / Heat treatment in a vacuum for 120 minutes to obtain an electrode. Then, the electrode was obtained by press-working with a roll press machine so that the density of a film|membrane (electrode active material layer) ^{might be set to 1.5 g/cm<3>.}

(3) Preparation of lithium half cell

In a glove box substituted with argon, the electrode was formed by punching a hole with a diameter of 16 mm, a two-pole type coin cell (product name of Hohsen Corp., trade name "HS Flat Cell)"') was witty. Subsequently, a separator made of a polypropylene porous film with a diameter of 24 mm perforated (STS TVCH, manufactured by LTD, trade name "SOSVFA, 500 μL of electrolyte is injected so as not to enter P2010") is placed, A lithium half cell was assembled by placing a metal lithium foil formed by punching a hole to a diameter of 16 mm, and sealing the exterior body of the two-pole type coin cell by screwing it. The electrolyte used here is a solution obtained by dissolving LiPF ₆ at a concentration of 1mol / L in a solvent of ethylene carbonate / ethylmethyl carbonate = 1/1 (mass ratio).

Examples 1-2 to 1-12, Comparative Examples 1-1 to 1-3

A lithium half cell was obtained in the same manner except that the composition was changed as shown in the following table.

The slurry dispersibility, the springback rate, and the discharge capacity retention rate in the table were measured according to the following method.

<Slurry dispersibility evaluation>

The following criteria visually evaluated the dispersibility immediately after slurry preparation.

(double-circle): The whole was in the form of a homogeneous paste, there was no liquid separation, and no aggregate was confirmed.

(circle): The whole was in the form of a substantially homogeneous paste, and although liquid separation was confirmed slightly, no aggregate was confirmed.

(triangle|delta): A small amount of agglomerates and a slightly large amount of liquid separation were confirmed at the bottom of the container.

×: A large number of clay-like aggregates were observed at the bottom of the container, and a large number of liquid separations were also observed.

<Evaluation of electrical characteristics: springback rate and discharge capacity retention rate>

(1) Charge/discharge measurement

The lithium half-cell prepared above was placed in a constant temperature bath at 25°C, charging was started with a constant current (0.1C), and charging was completed (cut-off) when the voltage reached 0.01V. Then, charging and discharging were repeated 30 times by starting discharging at a constant current (0.1C) and making the discharging complete (cut-off) when the voltage reached 1.0V.

(2) Electrode springback rate following repeated charging and discharging

After 30 cycles of the charge/discharge cycle test at room temperature (25° C.), the lithium half cell was disassembled and the thickness of the electrode was measured. The springback factor of the electrode was calculated|required by the following formula.

Springback rate = {(electrode thickness after 30 cycles - current collector thickness) / (electrode thickness before charging and discharging - current collector thickness)}×100 - 100 (%)

(3) Discharge capacity retention rate

The discharge capacity retention rate was calculated|required from the following formula.

Discharge capacity retention rate = {(discharge capacity at 30th cycle) / (discharge capacity at 1st cycle)}×100 (%)

In the above measurement conditions, &quot;1C&quot; represents a current value at which a cell having a certain constant electric capacity is discharged with a constant current and the discharge is completed in 1 hour. For example, "0.1C" means a current value at which discharge is completed over 10 hours, and "10C" means a current value at which discharge is completed over 0.1 hours.

As is evident from the table, in the evaluation of the electrode slurries prepared using the aqueous binder solutions of Examples 1-1 to 1-12 and the lithium half-cells prepared from the electrode slurries, the springback rate and the discharge capacity retention rate were all evaluated. It was good.

Heat shrinkage resistance, slip resistance, adhesiveness, rate resistance, and output characteristics of the obtained separator were measured by the following method.

<Heat shrinkage resistance>

The separators and separator/electrode laminates obtained in Examples and Comparative Examples were cut into a 12 cm wide x 12 cm long square, and a 10 cm square was drawn inside the square to obtain a test piece. The test piece was heat-treated by putting it in a constant temperature bath at 150°C and leaving it to stand for 1 hour. After the heat treatment, the area of the square drawn inside was measured, the change in the area before and after the heat treatment was calculated as the heat shrinkage rate, and the heat resistance was evaluated according to the following criteria. It shows that it is excellent in the heat-shrinkage resistance of a separator, so that thermal contraction rate is small.

○: Area shrinkage is less than 1%

△: Area shrinkage of 1% or more and less than 3%

×: Area shrinkage of 3% or more

<Partition resistance>

The separators and separator/electrode laminates obtained in Examples and Comparative Examples were cut into a square of 10 cm × 10 cm, the mass (X0) was accurately weighed, one side was attached to thick paper and fixed, and then a weight of 5 cm in diameter and 900 g covered with a cotton cloth. (分銅) was placed on the side of the ceramic layer, and these were rubbed against each other at a rotation speed of 50 nm for 10 minutes. After that, the mass (X1) is accurately measured again, and the following formula

Segmentability = {(X0-X1)/X0}×100

The following standards evaluated the separability resistance of the separator by calculating the separability (mass %) according to the following criteria.

A: Fragility is less than 2% by mass

B: Degradability is 2 mass % or more and less than 5 mass %

C: Fragility is 5 mass % or more

<Separator adhesion (peel strength)>

A test piece having a width of 2 cm and a length of 10 cm was cut out from the separators and separator/electrode laminates obtained in Examples and Comparative Examples and fixed with the coated side facing up. Next, on the surface of the ceramic layer of the test piece, an adhesive tape (“CELLOTAPE (registered trademark)” manufactured by Nichiban Co., Ltd.)) having a width of 15 mm (as stipulated in JIS Z1522) was applied. After attaching while pressing, using a tensile tester (“TENSILON RTM-100” manufactured by A&D Company, Limited) under 25°C conditions, from one end of the test piece, the adhesive tape The stress at the time of releasing in the 180° direction at a speed of 30 mm/min was measured. The measurement was performed 5 times, and it converted into the value per 15 mm of width, and computed the average value as peeling strength. The higher the peeling strength, the higher the adhesion strength between the substrate and the ceramic layer or the bonding between the ceramic layers, indicating that the ceramic layer or the ceramic layers are difficult to separate from the separator substrate.

<Rate Immunity, Output Characteristics>

(1) Manufacture of laminated lithium ion battery

In measuring the rate tolerance and output characteristics, a laminate type lithium ion battery was manufactured as follows.

(1-1) Preparation of negative electrode

Using a commercially available rotating revolving mixer (product name "Awatori Rentaro", manufactured by Shinki Co., Ltd.), styrene-butadiene rubber (SBS)/carboxymethylcellulose (CMC) (mass ratio 1/ 1) 2 parts of aqueous solution in terms of solid content and 98 parts of natural graphite (Ito Graphite Industrial Co., Ltd. product name "K-5F") were mixed. Ion-exchanged water was added thereto so that the solid content concentration was 40%, and the container was set in the mixer. Subsequently, after kneading|mixing at 2000 nm for 10 minutes, it defoamed for 1 minute and obtained the slurry for lithium ion batteries. The slurry for lithium ion batteries was put on the electrical power collector which consists of copper foil, and it apply|coated in film form using the doctor blade. After the slurry for lithium ion batteries was applied to the current collector and dried at 80° C. for 20 minutes to evaporate water and removed, it was adhered and bonded by a roll press. At this time, the density of the electrode active material layer was set to 1.0 g/cm ² . The joined product was heated at 120° C. in a vacuum dryer for 2 hours, cut out into a predetermined shape (a rectangular shape of 26 mm×31 mm), and an electrode active material layer had a thickness of 15 μm to obtain a negative electrode.

(1-2) Preparation of positive electrode

As a positive electrode active material, _{0.5 Cn, 0.2 Mb, 0.3} O ₂ , acetylene black as a conductive aid, and polyvinylidene fluoride (PD) as a binder, respectively, 88 parts by mass, 6 parts by mass, and 6 parts by mass of this mixture are mixed appropriately. of N-methyl-2-pyrrolidone (NMP) to prepare a slurry for a positive electrode of a lithium ion battery. Subsequently, an aluminum foil was prepared as the current collector of the positive electrode, the slurry for the positive electrode of a lithium ion battery was placed on the aluminum foil, and it was applied to form a film using a doctor blade. After drying the aluminum foil after apply|coating the slurry for lithium ion battery positive electrodes at 80 degreeC for 20 minutes, NMP was volatilized and removed, it closely_contact|adhered and joined by the roll press machine. At this time, the density of the positive electrode active material layer was set to 3.2 g/cm ² . The joined product was heated at 120°C with a vacuum dryer for 6 hours, cut out into a predetermined shape (a rectangular shape of 25 mm × 30 mm), and the thickness of the positive electrode active material layer was set to a positive electrode of about 45 µm.

(1-3) Manufacture of laminated lithium ion battery

A laminate type lithium ion secondary battery was produced using the negative electrode and the positive electrode or the positive electrode obtained in Examples. Specifically, the separators obtained in Examples and Comparative Examples were sandwiched between the positive electrode and the negative electrode to form an electrode plate group by sandwiching a rectangular sheet (27×32 mm, thickness 25 μm). This electrode plate group was covered with a laminate film of two sheets and one set, and after sealing the three sides, an electrolyte solution was injected into the bag-shaped laminate film. It used a solution obtained by dissolving LiPF ₆ at a concentration of 1mol / L in a solvent as an electrolytic solution, an ethylene carbonate / ethylmethyl carbonate = 1/1 (mass ratio). After that, by sealing the other side, four sides were hermetically sealed to obtain a laminate-type lithium ion secondary battery in which the electrode plate group and the electrolyte were sealed. In addition, the positive electrode and the negative electrode are provided with tabs electrically connectable to the outside, and a part of the tabs extend to the outside of the laminate type lithium ion secondary battery. When the laminate-type lithium ion battery manufactured by the above process was energized, there was no operational problem.

(2) Measurement of rate tolerance and output characteristics

Using the lithium ion secondary battery prepared above, it was charged at a voltage of 2.5 to 4.2 V at 25 ° C. at 0.1 C, and when the voltage became 4.2 V, the charging was continued at a constant voltage (4.2 V), and the current value was 0.01 The time at which C became the charging completion (cut-off) was made into. Then, charging and discharging at 0.1C to 2.5V were repeated 5 times, and after the 6th cycle, only the discharge was changed to 1C and charging and discharging were repeated 50 cycles. The value which computed the ratio of the 1C discharge capacity of the 6th cycle in the charge capacity of the 6th cycle as a percentage was made into the initial stage rate retention rate. The higher this value, the better the rate tolerance. The value obtained by calculating the ratio of the 1C discharge capacity at the 50th cycle to the 1C discharge capacity at the 5th cycle as a percentage was defined as the capacity retention ratio. The larger this value, the better the output characteristics.

Example 2-1

(1) Preparation of slurry for separator

5 parts by mass of the aqueous solution obtained in Formulation Example 1, in terms of solid content, and 113 parts by mass of water were stirred and mixed, 100 parts by mass of boehmite (average particle size 0.8 μm) was added, and a homogenizer (T25 digital ULTRA-TURRAX manufactured by IKA) It was disperse|distributed and stirred for 60 minutes at 15000 nm with a furnace. Further, ion-exchange water was added to adjust the viscosity to prepare a slurry.

(2) Preparation of separator: lamination of a layer (coating layer) of the separator slurry

A single-layer polyethylene separator base material (P base material) having a width of 250 mm, a length of 200 mm, and a thickness of 6 µm, manufactured by a wet method was prepared. The slurry liquid obtained above was apply|coated and dried using the gravure coater so that the thickness after drying might be set to 3.0 micrometers on one side of a separator, and the separator for lithium ion batteries was obtained.

Examples 2-2 to 2-20, Comparative Examples 2-1 to 2-4

A separator for lithium ion batteries was obtained in the same manner as in Example 2-1 except for changing as shown in the table below.

Example 2-21

In Example 2-5, the slurry liquid was coated on the positive electrode, not the separator, and applied and dried using a gap coater so that the thickness after drying was 3.0 μm, followed by drying to obtain a positive electrode for a lithium ion battery.

Example 2-22

In Example 2-5, except that the slurry liquid was coated on a polyethylene terephthalate nonwoven fabric substrate (P T substrate) having a width of 200 mm, a length of 200 mm, a thickness of 9 μm, and a weight per unit area of 11 g/m ² A separator for lithium ion batteries was obtained by the same operation as described above.

Claims (14)

Water-soluble poly which contains 50 to 85 mol% of the structural unit derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a) with respect to 100 mol% of the structural unit and does not contain a structural unit derived from unsaturated phosphoric acid (meth)acrylamide (A);
glyoxalin water-soluble crosslinking agent (A1);
electrode active material (B),
Conductive aid, slurry viscosity adjusting solvent
and water
Slurry for thermal crosslinking lithium ion battery electrodes.
According to claim 1,
In the water-soluble poly(meth)acrylamide (A), the water-soluble crosslinking agent (A1) is added in an amount of 0.001 to 100% by mass of the structural units derived from the N-unsubstituted or monosubstituted (meth)acrylamide group-containing compound (a). The slurry for thermal crosslinking-type lithium ion battery electrodes containing 3.0 mass %.
3. The method of claim 1 or 2,
The slurry for thermal crosslinking-type lithium ion battery electrodes in which the said electrode active material (B) contains 10 mass % or more of silicon or silicon oxide.
The thermal crosslinking type of claim 1 or 2 comprising a step of adding the water-soluble crosslinking agent (A1) of claim 1 or 2 to an aqueous solution containing the water-soluble poly(meth)acrylamide (A) of claim 1 or 2 A method for preparing a slurry for a lithium ion battery electrode.
An electrode for a lithium ion battery obtained by applying the slurry for a thermally crosslinkable lithium ion battery electrode of claim 1 or 2 to a current collector and performing a thermal crosslinking reaction.
A lithium ion battery comprising the electrode for a lithium ion battery of claim 5.
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