阅读说明：本技术 非水系二次电池功能层用浆料组合物、非水系二次电池用间隔件及非水系二次电池 (Slurry composition for functional layer of nonaqueous secondary battery, separator for nonaqueous secondary battery, and nonaqueous secondary battery ) 是由 浅井一辉 秋田康宏 园部健矢 于 2019-08-21 设计创作，主要内容包括：本发明的目的在于提供一种功能层用浆料组合物,其能够形成可与间隔件基材牢固地密合的功能层并且还能够提高使用具有该功能层的间隔件的二次电池的倍率特性。本发明的功能层用浆料组合物包含粘结材料和三聚氰胺化合物。上述粘结材料为具有选自羧酸基、羟基、氨基、环氧基、唑啉基、磺酸基、腈基和酰胺基中的至少一种官能团的聚合物,上述三聚氰胺化合物的体积平均粒径为20nm以上且300nm以下,而且,上述三聚氰胺化合物在上述粘结材料和上述三聚氰胺化合物的合计中所占的比例为0.5质量％以上且85质量％以下。(The purpose of the present invention is to provide a slurry composition for a functional layer, which can form a functional layer that can be firmly adhered to a spacer base material and can also improve the usabilityRate characteristics of a secondary battery having the separator of the functional layer. The slurry composition for a functional layer of the present invention comprises a binder material and a melamine compound. The adhesive material is selected from carboxylic acid group, hydroxyl group, amino group, epoxy group,)

1. A slurry composition for a functional layer of a nonaqueous secondary battery, comprising a binder and a melamine compound,

the adhesive material is selected from carboxylic acid group, hydroxyl group, amino group, epoxy group,A polymer having at least one functional group selected from the group consisting of an oxazoline group, a sulfonic acid group, a nitrile group and an amide group,

the melamine compound has a volume average particle diameter of 20nm to 300nm,

the melamine compound accounts for 0.5 to 85 mass% of the total of the binder and the melamine compound.

2. The slurry composition for a functional layer of a nonaqueous secondary battery according to claim 1, wherein a volume average particle diameter of the binder is 20nm or more and 300nm or less.

3. The slurry composition for a functional layer of a non-aqueous secondary battery according to claim 1 or 2, further comprising non-conductive particles.

4. A separator for a nonaqueous secondary battery, comprising a separator base material and a functional layer formed on the separator base material,

the functional layer is a dried product of the slurry composition for a functional layer of a nonaqueous secondary battery according to any one of claims 1 to 3.

5. The separator for a nonaqueous secondary battery according to claim 4, wherein a part of the dried product is present inside the separator base material.

6. The separator for a nonaqueous secondary battery according to claim 4 or 5, wherein the separator base is a microporous film containing at least one of a polyolefin resin and an aromatic polyamide resin, or a nonwoven fabric containing at least one of a polyolefin resin and an aromatic polyamide resin.

7. A nonaqueous secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte,

the separator is the separator for a nonaqueous secondary battery according to any one of claims 4 to 6.

Technical Field

The present invention relates to a slurry composition for a functional layer of a nonaqueous secondary battery, a separator for a nonaqueous secondary battery, and a nonaqueous secondary battery.

Background

Nonaqueous secondary batteries such as lithium ion secondary batteries (hereinafter, sometimes referred to as "secondary batteries") are small in size, light in weight, high in energy density, and capable of repeated charge and discharge, and are being used in a wide range of applications.

A secondary battery generally has electrodes (a positive electrode and a negative electrode) to isolate the positive electrode from the negative electrode to prevent a short circuit between the positive electrode and the negative electrode. Here, as the separator, a separator has been conventionally used in which a layer for imparting predetermined performance to a battery member, such as a porous film layer for improving heat resistance and strength, an adhesive layer for improving adhesion to an electrode, or the like, is provided on a surface of a separator base (hereinafter, these may be collectively referred to as a "functional layer for a nonaqueous secondary battery" or a "functional layer") (see, for example, patent document 1).

The functional layer can be formed by, for example, applying a slurry composition for a functional layer of a nonaqueous secondary battery containing a component such as a binder to a base material such as a spacer base material and drying the coating film on the base material.

For example, patent document 1 discloses the following technique: a technique of forming a porous film on a spacer substrate using a composition containing non-conductive particles, an acid group-containing polymer having a total acid group amount within a prescribed range, and a carbodiimide compound. Further, according to patent document 1, the use of the separator having the above porous film can improve the low-temperature output characteristics and the cycle characteristics of the lithium ion secondary battery.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2015-144084.

Disclosure of Invention

Problems to be solved by the invention

Here, in the case of the spacer having the conventional functional layer, it is necessary to bring the functional layer and the spacer base material into more firm adhesion and to make the secondary battery exhibit further excellent rate characteristics.

Accordingly, an object of the present invention is to provide a slurry composition for a functional layer of a nonaqueous secondary battery, which can form a functional layer that can be firmly adhered to a spacer base material and can also improve the rate characteristics of a nonaqueous secondary battery using a spacer having the functional layer.

Another object of the present invention is to provide a separator for a nonaqueous secondary battery, in which a functional layer and a separator base are firmly adhered to each other and a nonaqueous secondary battery can exhibit excellent rate characteristics.

It is another object of the present invention to provide a nonaqueous secondary battery having excellent rate characteristics.

Means for solving the problems

The present inventors have conducted intensive studies with a view to solving the above problems. Then, the inventors have found that if a functional layer is formed on a spacer base material using a slurry composition containing a binder made of a polymer having a predetermined functional group and a melamine compound having a volume average particle diameter within a predetermined range, and the proportion of the melamine compound in the total of the binder and the melamine compound is within a predetermined range, the functional layer and the spacer base material can be firmly adhered to each other, and a secondary battery can exhibit excellent rate characteristics by the spacer having the functional layer, and have completed the present invention.

That is, the present invention is directed to advantageously solving the above problems, and a slurry composition for a functional layer of a non-aqueous secondary battery according to the present invention comprises a binder and a melamine compound, wherein the binder is a polymer having a structure selected from the group consisting of a carboxylic acid group, a hydroxyl group, an amino group, an epoxy group, a carboxyl group, a,And a polymer having at least one functional group selected from an oxazoline group, a sulfonic acid group, a nitrile group and an amide group, wherein the melamine compound has a volume average particle diameter of 20nm or more and 300nm or less, and the melamine compound accounts for 0.5 mass% or more and 85 mass% or less of the total of the binder and the melamine compound. If a slurry composition containing a binder made of a polymer having at least one of the functional groups and a melamine compound having a volume average particle diameter within the above range is used in this manner, and the ratio of the melamine compound to the total of the binder and the melamine compound is within the above range, a functional layer that can be firmly adhered to the spacer base material can be produced. Further, if a spacer having the functional layer is used, the secondary battery can exhibit excellent rate characteristics.

In the present invention, the "volume average particle diameter" of the melamine compound can be measured by the method described in the examples of the present specification.

Here, the slurry composition for a functional layer of a nonaqueous secondary battery according to the present invention preferably has a volume average particle diameter of the binder of 20nm to 300 nm. If the volume average particle diameter of the binder is within the above range, the functional layer and the spacer base material can be more firmly adhered to each other, and the rate characteristics of the secondary battery can be further improved.

In the present invention, the "volume average particle diameter" of the binder can be measured by the method described in the examples of the present specification.

The slurry composition for a functional layer of a nonaqueous secondary battery of the present invention may further contain nonconductive particles. If the functional layer is formed using the slurry composition including the non-conductive particles, the heat resistance and the strength of the spacer having the functional layer can be improved.

In addition, in order to advantageously solve the above problems, the present invention provides a separator for a nonaqueous secondary battery, comprising a separator base material and a functional layer formed on the separator base material, wherein the functional layer is a dried product of any one of the slurry compositions for a functional layer of a nonaqueous secondary battery. The functional layer obtained by drying any of the slurry compositions described above can be firmly adhered to the spacer base material. Further, if a spacer having the functional layer is used, the secondary battery can exhibit excellent rate characteristics.

Here, in the separator for a nonaqueous secondary battery of the present invention, it is preferable that a part of the dried product is present inside the separator base material. In the spacer of the present invention having the spacer base material and the functional layer formed of the dried product of the slurry composition, the dried product of the slurry composition forms the functional layer and is also present inside the spacer base material so as to be connected to the functional layer, whereby the functional layer and the spacer base material can be further firmly adhered to each other.

In the present invention, it can be confirmed that "a part of a dried product of the slurry composition for a functional layer of a nonaqueous secondary battery is present inside the spacer base material" by using the method described in the examples of the present specification.

In the separator for a nonaqueous secondary battery of the present invention, the separator base is preferably a microporous film containing at least one of a polyolefin resin and an aromatic polyamide resin, or a nonwoven fabric containing at least one of a polyolefin resin and an aromatic polyamide resin. By using a microporous film containing at least one of a polyolefin resin and/or an aromatic polyamide resin, or a nonwoven fabric containing at least one of a polyolefin resin and/or an aromatic polyamide resin as a separator substrate, the cycle characteristics of the secondary battery can be improved and the rate characteristics can be further improved.

In addition, in order to advantageously solve the above-described problems, a nonaqueous secondary battery according to the present invention includes a positive electrode, a negative electrode, a separator, and an electrolyte solution, and the separator is any one of the above-described separators for nonaqueous secondary batteries. The secondary battery having any of the above-described separators for nonaqueous secondary batteries is excellent in rate characteristics.

Effects of the invention

According to the present invention, it is possible to provide a slurry composition for a functional layer of a nonaqueous secondary battery, which can form a functional layer that can be firmly adhered to a spacer base material and can improve the rate characteristics of a nonaqueous secondary battery using a spacer having the functional layer.

Further, according to the present invention, it is possible to provide a separator for a nonaqueous secondary battery, in which a functional layer and a separator base are firmly adhered to each other and a nonaqueous secondary battery can exhibit excellent rate characteristics.

Further, according to the present invention, a nonaqueous secondary battery having excellent rate characteristics can be provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

Here, the slurry composition for a functional layer of a nonaqueous secondary battery according to the present invention can be used for forming a functional layer that performs functions such as reinforcement and/or adhesion in a nonaqueous secondary battery. The separator for a nonaqueous secondary battery of the present invention includes a separator base material and a functional layer formed on at least one surface of the separator base material by using the slurry composition for a nonaqueous secondary battery functional layer of the present invention. The nonaqueous secondary battery of the present invention further includes the separator for a nonaqueous secondary battery of the present invention.

(slurry composition for functional layer of nonaqueous Secondary Battery)

The slurry composition of the present invention is a composition in which a binder and a melamine compound are dissolved and/or dispersed in a solvent. The slurry composition of the present invention may contain components (other components) other than the binder, the melamine compound, and the solvent.

The binder contained in the slurry composition of the present invention is a binder having a structure selected from the group consisting of a carboxylic acid group, a hydroxyl group, an amino group, an epoxy group, a carboxyl group,a polymer having at least one functional group selected from the group consisting of an oxazoline group, a sulfonic acid group, a nitrile group and an amide group. Further, the volume average particle diameter of the melamine compound contained in the slurry composition of the present invention is in the range of 20nm to 300 nm. Further, in the slurry composition of the present invention, the proportion of the amount of the melamine compound to be blended in the total 100 mass% of the amount of the binder and the amount of the melamine compound to be blended is 0.5 mass% or more and 85 mass% or less.

Further, if the functional layer formed of a dried product of the slurry composition of the present invention is provided on the spacer base material, the functional layer constituting the spacer and the spacer base material can be firmly adhered to each other. In addition, if the separator is used, the secondary battery can exhibit excellent rate characteristics. The reason why the functional layer formed by using the slurry composition of the present invention can improve the adhesion between the functional layer and the spacer base material and can exhibit excellent rate characteristics of the secondary battery is not clear, but is presumed as follows.

That is, it is presumed that the melamine compound and the binder exhibit excellent binding ability in combination because the amount of the melamine compound blended in the slurry composition of the present invention is 0.5 mass% or more and 85 mass% or less of the total amount of the binder and the melamine compound blended, and thus the binder having the functional group and the melamine compound interact well by hydrogen bonds or the like.

Further, the melamine compound contained in the slurry composition of the present invention exhibits good dispersibility by having a volume average particle diameter within the above range. By dispersing the melamine compound well as described above, the unevenness in the distribution of the binder that interacts with the melamine compound can be suppressed, and a functional layer in which the components such as the binder and the melamine compound are uniformly dispersed on the spacer base can be formed.

Further, it is considered that the functional layer formed using the slurry composition can be firmly adhered to the separator base material and the secondary battery having the functional layer can exhibit excellent battery characteristics (rate characteristics and the like) due to the synergistic effect of the above-described interaction between the melamine compound and the binder and the contribution of improving the dispersibility of melamine.

< adhesive Material >

The binder is a component that imparts adhesiveness to the functional layer formed on the surface of the spacer using the slurry composition.

< types of adhesive materials >)

Here, the binder is not particularly limited as long as it is a polymer having a predetermined functional group described later. For example, a polymer obtained by polymerizing a monomer composition containing a monomer capable of exhibiting adhesiveness (a synthetic polymer, for example, an addition polymer obtained by addition polymerization) can be used as the adhesive material. Examples of such polymers include aliphatic conjugated diene/aromatic monovinyl copolymer (a polymer mainly comprising aliphatic conjugated diene monomer units and aromatic monovinyl monomer units), acrylic polymer (a polymer mainly comprising alkyl (meth) acrylate monomer units), fluorine polymer (a polymer mainly comprising fluorine-containing monomer units), acrylic/acrylamide copolymer (a polymer mainly comprising (meth) acrylic acid units and (meth) acrylamide units), acrylonitrile polymer (a polymer mainly comprising (meth) acrylonitrile units), and the like. These may be used alone or in combination of two or more in any ratio. Among them, aliphatic conjugated diene/aromatic monovinyl copolymer, acrylic acid/acrylamide copolymer, acrylonitrile polymer, and acrylic polymer are preferable, and acrylic polymer is more preferable.

Here, known aliphatic conjugated diene monomers that can form aliphatic conjugated diene monomer units of the aliphatic conjugated diene/aromatic monovinyl copolymer, aromatic monovinyl monomers that can form aromatic monovinyl monomer units of the aliphatic conjugated diene/aromatic monovinyl copolymer, alkyl (meth) acrylate monomers that can form alkyl (meth) acrylate monomer units of the acrylic polymer, and fluorine-containing monomers that can form fluorine-containing monomer units of the fluorine-containing polymer can be used.

In addition, in the present invention, "comprising a monomer unit" means "comprising a repeating unit derived from the monomer in a polymer obtained using the monomer".

Further, in the present invention, "mainly comprising" one or more monomer units means "the content ratio of the one monomer unit or the sum of the content ratios of the plurality of monomer units exceeds 50% by mass with the amount of all repeating units contained in the polymer taken as 100% by mass".

Further, in the present invention, "(meth) acrylic acid" means acrylic acid and/or methacrylic acid, and "(meth) propylene" means propylene and/or (meth) propylene.

< functional group of adhesive Material >)

Here, from the viewpoint of firmly adhering the functional layer to the spacer base material and improving the rate characteristics of the secondary battery, the polymer used as the binder needs to have a carboxyl group, a hydroxyl group, an amino group, an epoxy group, a carboxyl group,At least one functional group selected from an oxazoline group, a sulfonic acid group, a nitrile group, and an amide group (hereinafter, these functional groups are sometimes collectively referred to as "specific functional groups"). Among these specific functional groups, a carboxylic acid group, a hydroxyl group, an amino group, an epoxy group, a nitrile group, and an amide group are preferable from the viewpoint of further firmly adhering the functional layer to the spacer base material and further improving the rate characteristics of the secondary battery. They may be used alone or in combination of two or more in an arbitrary ratioThe above.

The polymer having two or more functional groups is not particularly limited, and examples thereof include: a polymer having a carboxylic acid group and a hydroxyl group; a polymer having carboxylic acid groups and amide groups; a polymer having a carboxylic acid group, a nitrile group, and an amino group; a polymer having carboxylic acid groups, epoxy groups, hydroxyl groups, and nitrile groups.

The method for introducing the specific functional group into the polymer is not particularly limited, and a polymer containing a specific functional group-containing monomer unit may be obtained by preparing a polymer using a monomer containing the specific functional group (specific functional group-containing monomer), or a polymer having the specific functional group at the terminal may be obtained by modifying an arbitrary polymer, but the former is preferable. That is, in the polymer used as the binder, the specific functional group-containing monomer unit preferably includes a carboxylic acid group-containing monomer unit, a hydroxyl group-containing monomer unit, an amino group-containing monomer unit, an epoxy group-containing monomer unit, and a specific functional group-containing monomer unitAt least any one of the oxazoline-based monomer unit, the sulfonic-acid-group-containing monomer unit, the nitrile-group-containing monomer unit, and the amide-group-containing monomer unit, and more preferably at least any one of the carboxylic-group-containing monomer unit, the hydroxyl-group-containing monomer unit, the amino-group-containing monomer unit, the epoxy-group-containing monomer unit, the nitrile-group-containing monomer unit, and the amide-group-containing monomer unit.

Examples of the polymer containing two or more types of specific functional group-containing monomer units include: a polymer comprising carboxylic acid group-containing monomer units and hydroxyl group-containing monomer units; a polymer comprising carboxylic acid group-containing monomer units and amide group-containing monomer units; a polymer comprising a carboxylic acid group-containing monomer unit, a nitrile group-containing monomer unit, and an amino group-containing monomer unit; the polymer comprises a carboxylic acid group-containing monomer unit, an epoxy group-containing monomer unit, a hydroxyl group-containing monomer unit and a nitrile group-containing monomer unit.

Examples of the carboxylic acid group-containing monomer capable of forming a carboxylic acid group-containing monomer unit include monocarboxylic acids and derivatives thereof, dicarboxylic acids and anhydrides thereof, and derivatives thereof.

Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid.

Examples of the monocarboxylic acid derivative include 2-ethacrylic acid, isocrotonic acid, α -acetoxyacrylic acid, β -trans-aryloxyacrylic acid, α -chloro- β -E-methoxyacrylic acid, and the like.

Examples of the dicarboxylic acid include maleic acid, fumaric acid, and itaconic acid.

Examples of the dicarboxylic acid derivative include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, and fluoromaleic acid; maleic acid monoesters such as nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate.

Examples of the acid anhydride of the dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride.

Further, as the carboxylic acid group-containing monomer, an acid anhydride which generates a carboxylic acid group by hydrolysis can also be used. Among these, acrylic acid and methacrylic acid are preferable as the carboxylic acid group-containing monomer. One kind of the carboxylic acid group-containing monomer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

Examples of the hydroxyl group-containing monomer that can form a hydroxyl group-containing monomer unit include: ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-buten-1-ol and 5-hexen-1-ol; alkanol esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate and di-2-hydroxypropyl itaconate; is represented by the general formula: CH (CH)₂＝CR^a-COO-(C_qH_2qO)_pH (in the formula, p represents an integer of 2 to 9, q represents an integer of 2 to 4, R^aAn ester of a polyalkylene glycol represented by a hydrogen atom or a methyl group) and (meth) acrylic acid; mono (meth) acrylates of dihydroxy esters of dicarboxylic acids such as 2-hydroxyethyl-2 '- (meth) acryloyloxyphthalate and 2-hydroxyethyl-2' - (meth) acryloyloxysuccinate; ethylene such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl etherAn alkyl ether; mono (meth) allyl ethers of alkylene glycols such as (meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-3-hydroxypropyl ether, (meth) allyl-2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4-hydroxybutyl ether, and (meth) allyl-6-hydroxyhexyl ether; polyoxyalkylene glycol mono (meth) allyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether; mono (meth) allyl ethers of halogen and hydroxy-substituted (poly) alkylene glycols such as glycerol mono (meth) allyl ether, (meth) allyl-2-chloro-3-hydroxypropyl ether, and (meth) allyl-2-hydroxy-3-chloropropyl ether; mono (meth) allyl ethers of polyhydric phenols such as eugenol and isoeugenol, and halogen-substituted compounds thereof; (meth) allyl sulfides of alkylene glycols such as (meth) allyl-2-hydroxyethyl sulfide and (meth) allyl-2-hydroxypropyl sulfide; amides having a hydroxyl group such as N-hydroxymethylacrylamide (N-hydroxymethylacrylamide), N-hydroxymethylmethacrylamide, N-hydroxyethylacrylamide, and N-hydroxyethylmethacrylamide. One kind of the hydroxyl group-containing monomer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

Here, in the present invention, "(meth) allyl" means allyl and/or methallyl.

Examples of the amino group-containing monomer capable of forming an amino group-containing monomer unit include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, aminoethyl vinyl ether, and dimethylaminoethyl vinyl ether. Further, one kind of the amino group-containing monomer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

Herein, in the present invention, (meth) acrylate means acrylate and/or methacrylate.

Examples of the epoxy group-containing monomer that can form an epoxy group-containing monomer unit include monomers containing a carbon-carbon double bond and an epoxy group.

Examples of the monomer having a carbon-carbon double bond and an epoxy group include: unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, and o-allyl phenyl glycidyl ether; monoepoxides of dienes or polyenes such as butadiene monoepoxide, chloroprene monoepoxide, 4, 5-epoxy-2-pentene, 3, 4-epoxy-1-vinylcyclohexene, and 1, 2-epoxy-5, 9-cyclododecene; alkenyl epoxides such as 3, 4-epoxy-1-butene, 1, 2-epoxy-5-hexene, and 1, 2-epoxy-9-decene; glycidyl esters of unsaturated carboxylic acids such as glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl 4-heptenoic acid, glycidyl sorbate, glycidyl linoleate, glycidyl 4-methyl-3-pentenoate, glycidyl 3-cyclohexene carboxylate, and glycidyl 4-methyl-3-cyclohexene carboxylate. The epoxy group-containing monomer may be used alone or in combination of two or more kinds at an arbitrary ratio.

As can formContaining oxazoline-based monomer unitsExamples of oxazoline-based monomers include 2-vinyl-2-Oxazoline, 2-vinyl-4-methyl-2-Oxazoline, 2-vinyl-5-methyl-2-Oxazoline, 2-isopropenyl-2-Oxazoline, 2-isopropenyl-4-methyl-2-Oxazoline, 2-isopropenyl-5-methyl-2-Oxazoline, 2-isopropenyl-5-ethyl-2-Oxazoline, and the like. In addition, containOne oxazoline-based monomer may be used alone, or two or more oxazoline-based monomers may be used in combination at an arbitrary ratio.

Examples of the sulfonic acid group-containing monomer capable of forming a sulfonic acid group-containing monomer unit include vinylsulfonic acid, methylvinylsulfonic acid, (meth) allylsulfonic acid, styrenesulfonic acid, ethyl (meth) acrylate-2-sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid. One kind of the sulfonic acid group-containing monomer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

Examples of the nitrile group-containing monomer that can form a nitrile group-containing monomer unit include α, β -ethylenically unsaturated nitrile monomers. Specifically, the α, β -ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α, β -ethylenically unsaturated compound having a nitrile group, and examples thereof include: acrylonitrile; α -halogenated acrylonitrile such as α -chloroacrylonitrile and α -bromoacrylonitrile; and alpha-alkylacrylonitrile such as methacrylonitrile and alpha-ethylacrylonitrile. One kind of nitrile group-containing monomer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

Examples of the amide group-containing monomer that can form the amide group-containing monomer unit include acrylamide, methacrylamide, and the like. The amide group-containing monomer may be used alone or in combination of two or more kinds at an arbitrary ratio.

When the amount of all the repeating units contained in the polymer as the binder is defined as 100% by mass, the content of the specific functional group-containing monomer unit in the polymer is preferably 0.3% by mass or more, more preferably 0.8% by mass or more, still more preferably 2% by mass or more, particularly preferably 4% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 9% by mass or less. If the content ratio of the specific functional group-containing monomer unit in the polymer is within the above range, the functional layer and the spacer base material can be more firmly adhered to each other, and the rate characteristics of the secondary battery can be further improved.

In the present invention, the content ratio of each monomer unit (repeating unit) in the polymer can be used¹H-NMR、¹³Nuclear Magnetic Resonance (NMR) methods such as C-NMR.

< preparation method of adhesive Material >)

The method for producing the polymer as the binder is not particularly limited. The polymer as the binder can be produced, for example, by polymerizing a monomer composition containing the above-mentioned monomer in an aqueous solvent. The content ratio of each monomer in the monomer composition can be determined according to the content ratio of a desired monomer unit (repeating unit) in the polymer.

The polymerization method is not particularly limited, and any of solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, and the like can be used. As the polymerization reaction, any of ionic polymerization, radical polymerization, living radical polymerization, various condensation polymerization, addition polymerization, and the like can be used. In addition, when polymerization is carried out, a known emulsifier or polymerization initiator can be used as needed.

< Properties of Binder >

[ volume average particle diameter ]

The volume average particle diameter of the binder is preferably 20nm or more, more preferably 30nm or more, further preferably 50nm or more, preferably 300nm or less, more preferably 270nm or less, further preferably 230nm or less, and particularly preferably 200nm or less. When the volume average particle diameter of the binder is 20nm or more, the functional layer formed using the slurry composition can be more firmly adhered to the spacer base material. On the other hand, if the volume average particle diameter of the binder is 300nm or less, the secondary battery can exhibit more excellent rate characteristics by the spacer having the functional layer formed of the paste composition.

In addition, the binder is preferably water-insoluble. In the present invention, the term "water-insoluble" as a component means that the insoluble component is 90 mass% or more when 0.5g of the component is dissolved in 100g of water at 25 ℃.

[ glass transition temperature ]

The glass transition temperature of the binder is preferably less than 25 ℃, more preferably 0 ℃ or less, and still more preferably-20 ℃ or less. If the glass transition temperature of the binder is less than 25 ℃, the functional layer formed using the paste composition can be more firmly adhered to the spacer base material. The lower limit of the glass transition temperature of the binder is not particularly limited, but is usually-100 ℃ or higher.

In the present invention, the "glass transition temperature" can be measured by the method described in the examples of the present specification.

[ Carboxylic acid group content ]

The amount of carboxylic acid groups (mmol/g, hereinafter referred to as "carboxylic acid group content") contained in 1g of the binder polymer is preferably 0.01mmol/g or more, more preferably 0.1mmol/g or more, still more preferably 0.2mmol/g or more, yet more preferably 0.23mmol/g or more, yet more preferably 0.5mmol/g or more, particularly preferably 0.57mmol/g or more, preferably 15mmol/g or less, more preferably 10mmol/g or less, yet more preferably 9.69mmol/g or less, still more preferably 7mmol/g or less, yet more preferably 5mmol/g or less, and particularly preferably 4.86mmol/g or less. If the carboxylic acid group content of the polymer as the binder is 0.01mmol/g or more, the functional layer and the spacer base material can be more firmly adhered by sufficiently interacting the binder and the melamine compound. On the other hand, if the carboxylic acid group content of the polymer as the binder is 15mmol/g or less, it is possible to prevent the stability of the slurry composition from being lowered, and to improve the cycle characteristics of the secondary battery.

In the present invention, the "carboxylic acid group content" can be calculated from a charged amount (for example, an amount of the carboxylic acid group-containing monomer used when the polymer as the binder is adjusted), and can be calculated by measuring an acid amount of the binder by titration.

[ nitrile group content ]

The amount of nitrile groups (mmol/g, hereinafter referred to as "nitrile group content") contained in 1g of the binder polymer is preferably 1mmol/g or more, more preferably 2mmol/g or more, further preferably 2.57mmol/g or more, preferably 40mmol/g or less, more preferably 35mmol/g or less, further preferably 30mmol/g or less, further preferably 21.6mmol/g or less, further preferably 15mmol/g or less, particularly preferably 11.3mmol/g or less, and most preferably 5mmol/g or less. When the nitrile group content of the polymer as the binder is 1mmol/g or more, the functional layer and the spacer base material can be more firmly adhered by sufficiently interacting the binder with the melamine compound. On the other hand, if the nitrile group content of the polymer as the binder is 40mmol/g or less, the binder in the slurry composition is prevented from aggregating, and the rate characteristics of the secondary battery can be sufficiently ensured.

In the present invention, the "nitrile group content" can be calculated from the charged amount (for example, the amount of the nitrile group-containing monomer used when the polymer as the adhesive material is adjusted), and can be calculated by measuring the nitrogen content in the adhesive material by the modified Dumas method.

< Melamine Compound >

The melamine compound is an ingredient added to the slurry composition containing the binder material so that the binding ability of the binder material can be improved.

Here, in the present invention, examples of the "melamine compound" include melamine, derivatives of melamine, and salts thereof.

The melamine and the melamine derivative include, for example, compounds represented by the following formula (I).

[ chemical formula 1]

In the formula (I), each A independently represents a hydroxyl group or-NR¹R²(R¹And R²Each independently represents a hydrogen atom, a hydrocarbon group or a hydroxyl group-containing hydrocarbon group. Furthermore, in formula (I) a plurality of R is present¹In the case of (2), there are a plurality of R¹May be the same or different, in the presence of a plurality of R²In the case of (2), there are a plurality of R²May be the same or different).

Herein, R is¹And R²The hydrocarbon group and the hydroxyl group-containing hydrocarbon group of (a) may be interrupted by 1 or 2 or more oxygen atoms (-O-) (wherein, in the case where 2 or more oxygen atoms are interrupted, they are not adjacent to each other). And, R¹And R²The number of carbon atoms of the hydrocarbon group and the hydroxyl group-containing hydrocarbon group of (2) is not particularly limited, but is preferably 1 to 5.

The melamine and the salt of a melamine derivative are not particularly limited, and examples thereof include a sulfate salt and a cyanurate salt.

One melamine compound may be used alone, or two or more melamine compounds may be used in combination at an arbitrary ratio. Among them, from the viewpoint of more firmly adhering the functional layer and the spacer base material and further improving the rate characteristics of the secondary battery, melamine, ammeline, and ammelide, and salts thereof with cyanuric acid are preferable, and melamine, ammeline, and salts thereof with cyanuric acid (melamine cyanurate) are more preferable. Further, from the viewpoint of more firmly adhering the functional layer to the spacer base material and improving the cycle characteristics of the secondary battery, melamine cyanurate is more preferable.

< volume average particle diameter of melamine Compound >)

The volume average particle diameter of the melamine compound is required to be 20nm or more and 300nm or less, preferably 30nm or more, more preferably 40nm or more, further preferably 50nm or more, preferably 250nm or less, more preferably 200nm or less, and further preferably 190nm or less. If the volume average particle diameter of the melamine compound is less than 20nm, the functional layer formed using the slurry composition cannot be strongly adhered to the spacer base material. On the other hand, if the volume average particle diameter of the melamine compound exceeds 300nm, the functional layer formed using the slurry composition cannot be strongly adhered to the spacer base material, and the secondary battery cannot exhibit excellent rate characteristics and cycle characteristics by the spacer having the functional layer.

The volume average particle size of the melamine compound can be adjusted by, for example, changing the method and/or conditions for pulverization/pulverization after synthesis of the melamine compound. Here, the method of pulverizing/crushing the melamine compound is not particularly limited, and can be performed by a wet/dry media mixer, a planetary media mixer, a wet jet mill, an ultrasonic homogenizer, or the like.

< coupling treatment >

The melamine compound may be subjected to a treatment with a coupling agent (coupling treatment). By using the melamine compound subjected to the coupling treatment, the functional layer and the spacer base material can be more firmly adhered to each other, and the secondary battery can exhibit more excellent rate characteristics.

Examples of the coupling agent used for the coupling treatment include a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent. Here, as the coupling agent, a coupling agent having a functional group (crosslinkable functional group) capable of undergoing a crosslinking reaction with a molecular chain of the resin (binder) in its molecular structure is preferable. Specific examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, a mercapto group, a halogen group, a vinyl group, a methacryloyl group, an acryloyl group, a siloxy group, a peroxy group, and an epoxy group. The coupling agent may have only one crosslinkable functional group, or may have two or more crosslinkable functional groups. Among these crosslinkable functional groups, a carboxyl group, a carbonyl group, and an epoxy group are preferable, and an epoxy group is more preferable.

Examples of the silane coupling agent include: alkoxysilanes having a vinyl group such as vinyltriethoxysilane and vinyltris (. beta. -methoxyethoxy) silane; alkoxysilanes having a methacryloyl group or an acryloyl group, such as γ -acryloyloxypropyltrimethoxysilane and γ -methacryloyloxypropyltrimethoxysilane; alkoxysilanes having an epoxy group such as γ -glycidoxypropyltrimethoxysilane, β - (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, and γ -glycidoxypropylmethyldiethoxysilane; alkoxysilanes having an amino group such as γ -aminopropyltriethoxysilane, N- β - (aminoethyl) γ -aminopropyltrimethoxysilane, N- β - (aminoethyl) γ -aminopropylmethyldimethoxysilane and the like; alkoxysilanes having a mercapto group such as γ -mercaptopropyltrimethoxysilane; alkoxysilanes having a halogen group such as γ -chloropropyltrimethoxysilane; silanes having a vinyl group and a halogen group, such as vinyltrichlorosilane; methyltriacetoxysilane, and the like.

Examples of the titanium coupling agent include isopropyltriisostearoyltitanate, isopropyltris (dodecylbenzenesulfonyl) titanate, isopropyltris (dioctylphosphatoxy) titanate, tetraisopropylbis (dioctylphosphatoxy) titanate, tetraoctylbis (ditridecylphosphonoxy) titanate, tetrakis (2, 2-diallyloxymethyl-1-butyl) bis (ditridecylato) phosphonoxy titanate, bis (dioctylphosphatoxy) oxyacetoxy titanate, bis (dioctylphosphatoxy) ethylene titanate, isopropyltrioctyl titanate, isopropylisostearoyl titanate dimethacrylate, stearoylisopropylisopropyldiacrylate, isopropyltris (dioctylphosphatoxy) titanate, isopropyltris (N-amidoethylamino) titanate, isopropyltris (N-amidoethyl) titanate, and the like, Dicumylphenoxyacetic acid acyloxy titanate, diisostearyl ethylene titanate and the like.

Examples of the aluminum coupling agent include an acetoacetoxyaluminum diisopropyl ester and the like.

These coupling agents may be used alone or in combination of two or more in any ratio. Also, among them, gamma-glycidoxypropyltrimethoxysilane is preferable.

The method for coupling the melamine compound is not particularly limited. For example, a melamine compound subjected to a coupling treatment can be obtained by stirring a solution in which a melamine compound and a coupling agent are dissolved or dispersed in an arbitrary solvent.

< blending amount ratio of Binder to Melamine Compound >

Here, the proportion of the melamine compound in the slurry composition in the total of the binder and the melamine compound needs to be 0.5 mass% or more and 85 mass% or less, preferably 1 mass% or more, more preferably 10 mass% or more, further preferably 15 mass% or more, particularly preferably 20 mass% or more, preferably 80 mass% or less, more preferably 70 mass% or less, further preferably 60 mass% or less. If the proportion of the melamine compound in the slurry composition in the total of the binder and the melamine compound is less than 0.5 mass%, the functional layer and the separator base material cannot be firmly adhered to each other, and the rate characteristics and cycle characteristics of the secondary battery are degraded. Further, the permeability of the spacer having the functional layer may be impaired. On the other hand, if the proportion of the melamine compound in the slurry composition in the total of the binder and the melamine compound exceeds 85 mass%, the functional layer and the spacer base material cannot be firmly adhered to each other.

< solvent >

The solvent contained in the slurry composition is not particularly limited as long as it can dissolve or disperse the binder and the melamine compound, and any of water and an organic solvent can be used. Examples of the organic solvent include acetonitrile, N-methyl-2-pyrrolidone, tetrahydrofuran, acetone, acetylpyridine, cyclopentanone, dimethylformamide, dimethyl sulfoxide, methylformamide, methyl ethyl ketone, furfural, ethylenediamine, dimethylbenzene (xylene), methylbenzene (toluene), cyclopentyl methyl ether, and isopropyl alcohol.

These solvents can be used alone or in combination in any mixing ratio.

< other ingredients >

The slurry composition of the present invention may optionally contain known additives that can be added to the functional layer, such as other polymers, conductive materials, wetting agents, viscosity modifiers, and electrolyte additives, which are different from the binder in composition and properties, in addition to the binder, the melamine compound, and the solvent.

The slurry composition of the present invention may contain nonconductive particles as another component in order to improve various properties such as heat resistance and strength of the obtained functional layer. The nonconductive particles are not particularly limited, and known nonconductive particles that can be used in secondary batteries can be cited.

Specifically, as the non-conductive particles, both inorganic fine particles and organic fine particles can be used, and inorganic fine particles are generally used. Here, as the material of the non-conductive particles, a material that stably exists in the use environment of the secondary battery and is electrochemically stable is preferable. From such a viewpoint, preferable examples of the non-conductive particles include aluminum oxide (alumina), hydrated aluminum oxide (boehmite), silicon oxide, magnesium oxide (magnesia), calcium oxide, titanium oxide (titania), and BaTiO₃Oxide particles such as ZrO and alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; covalent crystalline particles of silicon, diamond, etc.; insoluble ion crystal particles such as barium sulfate, calcium fluoride, barium fluoride, and the like; clay fine particles such as talc and montmorillonite. Further, these particles may be subjected to element substitution, surface treatment, solid solution treatment, and the like as necessary.

The electrically non-conductive particles may be used singly or in combination of two or more. The glass transition temperature of the organic fine particles is not particularly limited, but is preferably 25 ℃ or higher.

Here, the volume average particle diameter of the non-conductive particles is preferably 20nm or more, and preferably 400nm or less, and if the volume average particle diameter of the non-conductive particles is 20nm or more, the functional layer formed using the slurry composition can be sufficiently firmly adhered to the spacer base material. On the other hand, if the volume average particle diameter of the non-conductive particles is 400nm or less, the secondary battery can exhibit excellent rate characteristics by the spacer having the functional layer formed of the paste composition.

In addition, when the slurry composition of the present invention contains the nonconductive particles, the amount of the nonconductive particles in the slurry composition is preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the total amount of the binder and the melamine compound, from the viewpoint of achieving desired improvement in the characteristics provided to the functional layer by the nonconductive particles and sufficiently and firmly adhering the functional layer and the spacer base material.

The slurry composition of the present invention may contain a foaming agent such as sodium bicarbonate and a flame retardant such as a phosphorus compound and/or a silicon compound, from the viewpoint of improving the safety of the secondary battery. These other components may be used alone or in combination of two or more.

The contents of the foaming agent and the flame retardant may be, for example, 30 parts by mass or less or 15 parts by mass or less, respectively, with respect to 100 parts by mass of the binder.

< method for producing slurry composition >

The method for preparing the slurry composition is not particularly limited, and the slurry composition can be prepared by mixing the above components. For example, the binder composition can be prepared by preparing a binder composition containing a binder, a melamine compound, and a solvent, and then adding and mixing other components (non-conductive particles and the like) that can be used as needed and an additional solvent to the obtained binder composition.

(nonaqueous Secondary Battery separator)

The spacer of the present invention includes a spacer base material and a functional layer, and the functional layer is formed from a dried product of the slurry composition of the present invention. In the spacer of the present invention, since the functional layer is formed from the slurry composition of the present invention, the functional layer and the spacer base material can be firmly adhered to each other. Furthermore, the separator of the present invention can provide a secondary battery with excellent battery characteristics (rate characteristics, etc.).

< spacer substrate >

The spacer base material is not particularly limited, and known spacer base materials such as organic spacer base materials can be mentioned. The organic separator substrate is a porous member formed of an organic material, and in the case of taking an example of the organic separator substrate, from the viewpoint of improving the cycle characteristics of the secondary battery and further improving the rate characteristics, preferable examples thereof include a microporous membrane or a nonwoven fabric comprising a polyolefin resin such as polyethylene or polypropylene, an aromatic polyamide resin, and the like, and a microporous membrane or a nonwoven fabric made of polyethylene is more preferable in terms of excellent strength.

< functional layer >

As described above, the functional layer is formed from the dried product of the slurry composition of the present invention. That is, the functional layer of the spacer of the present invention generally contains at least a binder and a melamine compound, and optionally contains other components such as nonconductive particles. Since each component contained in the functional layer is each component contained in the slurry composition of the present invention, the preferred presence ratio of each component is the same as the preferred presence ratio of each component in the slurry composition of the present invention. In addition, the polymer such as the adhesive material is a functional group having crosslinking property (for example, epoxy group andoxazoline group, etc.), the polymer may be crosslinked (that is, the functional layer may contain a crosslinked product of the binder) at the time of drying the slurry composition or at the time of heat treatment optionally performed after drying.

The functional layer, which is a dried product of the slurry composition, may contain a solvent such as water derived from the slurry composition, and the content of the solvent in the functional layer is preferably 3 mass% or less, more preferably 1 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0 mass% or less (detection limit or less), from the viewpoint of ensuring battery characteristics (rate characteristics and the like) of the secondary battery.

Preferably, the dried slurry composition is present inside the spacer substrate so as to form a functional layer on the surface of the spacer substrate and to be connected to the functional layer. In this way, a part of the dried material forming the functional layer penetrates into the spacer base material, and the functional layer and the spacer base material can be more firmly adhered to each other.

In order to allow a part of the dried product to be present inside the spacer base material, for example, when the slurry composition is applied to the surface of the base material, the slurry composition may be impregnated into the spacer base material, and the spacer base material may be dried in a state in which the slurry composition is present inside. In order to impregnate the inside of the spacer base material with the slurry composition, the slurry composition may be impregnated by reducing the volume average particle diameter of the components (binder, melamine compound, etc.) in the slurry composition, reducing the viscosity of the slurry composition, or using a spacer base material having a large porosity and/or pore diameter.

< method for producing spacer >

Examples of a method for producing the spacer of the present invention by forming a functional layer on a spacer substrate include the following methods.

1) A method in which the slurry composition of the present invention is supplied to the surface of a spacer base material, followed by drying; and

2) a method of producing a functional layer by supplying the slurry composition of the present invention onto a release substrate and drying the same, and transferring the obtained functional layer onto the surface of a spacer substrate.

Among them, the method of 1) above is particularly preferable because the layer thickness of the functional layer can be easily controlled. Specifically, the method of 1) includes a step of supplying the slurry composition onto the spacer base material (supply step) and a step of drying the slurry composition applied onto the spacer base material to form the functional layer (drying step).

< supply step >)

In the supply step, examples of a method for supplying the slurry composition to the spacer base material include a method for coating the slurry composition on the surface of the spacer base material and a method for immersing the spacer base material in the slurry composition. Specific examples of these methods are not particularly limited, and examples thereof include a doctor blade method, a reverse roll coating method, a direct roll coating method, an gravure method, an extrusion method, a brush coating method, a dip coating method, a spray coating method, and a vacuum impregnation method.

In order to impregnate the inside of the spacer base material with the slurry composition, a dip coating method, a spray coating method, a vacuum impregnation method, and a gravure printing method are preferably used.

< drying Process >)

In the drying step, a method for drying the slurry composition on the spacer base is not particularly limited, and a known method can be used. Examples of the drying method include drying with warm air, hot air, or low-humidity air; vacuum drying; drying by irradiation with infrared rays, electron beams, or the like. To avoid the risk of thermal decomposition, sublimation, of the melamine compound used, the drying temperature is preferably less than 200 c, more preferably less than 150 c.

In addition, the thickness of the functional layer formed on the spacer base material as described above is preferably 0.1 μm or more and 10 μm or less from the viewpoint of ensuring the strength of the functional layer and further improving the rate characteristics of the secondary battery.

(nonaqueous Secondary Battery)

The secondary battery of the present invention has the above-described separator of the present invention. More specifically, the nonaqueous secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolytic solution, and the separator is the above-described separator for a nonaqueous secondary battery of the present invention. Furthermore, the secondary battery of the present invention can exhibit excellent battery characteristics (e.g., rate characteristics).

< Positive electrode, negative electrode >

The positive electrode and the negative electrode used for the secondary battery of the present invention are not particularly limited, and known positive electrodes, negative electrodes, and separators can be used.

< electrolyte solution >

As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is generally used. As the supporting electrolyte, a lithium salt can be used in, for example, a lithium ion secondary battery. Examples of the lithium salt include LiPF₆、LiAsF₆、LiBF₄、LiSbF₆、LiAlCl₄、LiClO₄、CF₃SO₃Li、C₄F₉SO₃Li、CF₃COOLi、(CF₃CO)₂NLi、(CF₃SO₂)₂NLi、(C₂F₅SO₂) NLi, etc. Among them, LiPF is preferable because it is easily dissolved in a solvent and shows a high dissociation degree₆、LiClO₄、CF₃SO₃And Li. One kind of electrolyte may be used alone, or two or more kinds may be used in combination. In general, the lithium ion conductivity tends to be higher as the support electrolyte having a higher dissociation degree is used, and therefore the lithium ion conductivity can be adjusted depending on the type of the support electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte, and for example, in a lithium ion secondary battery, carbonates such as dimethyl carbonate (DMC), Ethylene Carbonate (EC), diethyl carbonate (DEC), Propylene Carbonate (PC), Butylene Carbonate (BC), Ethyl Methyl Carbonate (EMC), and Vinylene Carbonate (VC); esters such as γ -butyrolactone and methyl formate; ethers such as 1, 2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide, and the like. Further, a mixed solution of these solvents may be used. Among them, carbonates are preferable because of their high dielectric constant and wide stable potential region. In general, the lithium ion conductivity tends to be higher as the viscosity of the solvent used is lower, and therefore, the lithium ion conductivity can be adjusted depending on the type of the solvent.

In addition, the concentration of the electrolyte in the electrolytic solution can be appropriately adjusted. In addition, known additives may be added to the electrolyte.

< method for producing nonaqueous Secondary Battery >

The secondary battery of the present invention can be manufactured by, for example, stacking the positive electrode and the negative electrode with a separator interposed therebetween, winding or folding the stack into a battery container as needed, injecting an electrolyte solution into the battery container, and sealing the battery container. At least one of the positive electrode, the negative electrode, and the separator is a battery member having the functional layer of the present invention. In addition, an overcurrent prevention element such as a porous metal mesh, a fuse, or a PTC element, a guide plate, or the like may be placed in the battery container as necessary to prevent a pressure rise or overcharge/discharge in the battery. The shape of the battery may be any of coin type, button type, sheet type, cylindrical type, rectangular type, flat type, and the like, for example.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following description, "%" and "part" representing amounts are based on mass unless otherwise specified.

In the examples and comparative examples, the volume average particle diameters of the binder material, the melamine compound, and the non-conductive particles; the glass transition temperature of the bonding material; adhesion of the functional layer to the spacer base material; permeability of the spacer; the presence or absence of a dried product of the slurry composition inside the spacer base material, and the rate characteristics and cycle characteristics of the secondary battery were measured and evaluated by the following methods.

< volume average particle diameter >

The volume average particle diameters of the binder, the melamine compound and the non-conductive particles were measured by the laser diffraction method as described below. First, an aqueous dispersion containing a binder to be measured, a melamine compound and non-conductive particles each at a solid content concentration of 0.1 mass% was prepared, and a sample for measurement was prepared. Then, in the particle size distribution (volume basis) measured by a dynamic light scattering particle size distribution measuring apparatus (HORIBA, ltd., product name "SZ-100"), the particle size at which the cumulative percentage of passage calculated from the small diameter side reached 50% was taken as the volume average particle size.

< glass transition temperature >

First, an aqueous dispersion containing the prepared binder was dried at a temperature of 25 ℃ for 48 hours, and the obtained powder was used as a sample for measurement.

Then, 10mg of a sample for measurement was weighed in an aluminum dish, and measured by a differential thermal analysis measuring apparatus (product name "EXSTAR DSC 6220" manufactured by Hitachi High-Tech Science Corporation) at a temperature rise rate of 20 ℃/min within a measurement temperature range of-100 ℃ to 200 ℃ under the conditions specified in JIS Z8703, to obtain a differential scanning thermal analysis (DSC) curve. As a control, an empty aluminum dish was used. The temperature at which the differential signal (DDSC) shows a peak during the temperature rise was obtained as the glass transition temperature (. degree. C.).

< adhesion >

The prepared spacer having the functional layer was cut into a rectangular shape having a length of 100mm and a width of 10mm to prepare a test piece, the functional layer surface of the test piece was attached to a test stand (substrate made of SUS) via a transparent tape (transparent tape specified in JIS Z1522) with the functional layer surface facing downward. Then, one end of the spacer was pulled in the vertical direction at a pulling rate of 50 mm/min and peeled off, and the stress (N/m) at that time was measured (in addition, a transparent tape was fixed on a test bench). The measurement was performed 3 times in total, and the average value was obtained and evaluated as the peel strength by the following criteria. The larger the value of the peel strength, the more firmly the functional layer and the spacer base material are adhered to each other.

A: peel strength of 40.0N/m or more

B: a peel strength of 30.0N/m or more and less than 40.0N/m

C: a peel strength of 20.0N/m or more and less than 30.0N/m

D: peeling strength is less than 20.0N/m

< permeability >

The Gurley value (sec/100 ccAir) was measured for the spacer substrate used for the spacer production and the spacer having the functional layer formed thereon using a digital Wangshan air permeability smoothness tester (manufactured by Asahi Seiki Kaisha, product name "EYO-5-1M-R"). Specifically, the increase Δ G in the gurley value (G1 to G0) is obtained from the gurley value G0 of the "spacer base material" and the gurley value G1 of the "spacer" on which the functional layer is formed, and evaluated by the following criteria. The smaller the increase Δ G in the gurley value, the smaller the decrease in the permeability of the spacer due to the formation of the functional layer, and the higher the ion conductivity of the spacer.

A: Δ G less than 10 sec/100 ccAir

B: Δ G is 10 sec/100 ccAir or more and less than 15 sec/100 ccAir

C: Δ G is 15 sec/100 ccAir or more and less than 20 sec/100 ccAir

D: Δ G is 20 sec/100 ccAir or more and less than 30 sec/100 ccAir

E: Δ G is 30 seconds/100 ccAir or more

< Presence or absence of dried slurry composition inside spacer base >

The obtained spacer was cut in the thickness direction using a CROSS-SECTION sample preparation apparatus (product name "CROSS separation packer (registered trademark)", manufactured by JEOL corporation). Then, the cut surface was observed by a field emission scanning electron microscope (manufactured by Hitachi High-Tech corporation, product name "S4700") to confirm whether or not a dried product of the slurry composition (specifically, the binder and/or the melamine compound) was present inside the spacer base material.

The presence or absence of a dried product of the slurry composition inside the spacer base material can also be confirmed by glow discharge luminescence analysis, EPMA analysis using Os staining, or the like.

< Rate characteristics >

The prepared lithium ion secondary battery was injected with an electrolyte and then allowed to stand at 25 ℃ for 5 hours. Then, the cell was charged to a cell voltage of 3.65V by a galvanostatic method at a temperature of 25 ℃ and 0.2C, and then aged at a temperature of 60 ℃ for 12 hours. Then, the cell was discharged to a cell voltage of 3.00V by a constant current method at 25 ℃ and 0.2C. Then, CC-CV charging was performed by a constant current of 0.2C (upper limit cell voltage was 4.35V), and CC discharge was performed by a constant current of 0.2C until the cell voltage was 3.00V. The charge and discharge at 0.2C were repeated 3 times.

Then, constant current charging and discharging was performed at a cell voltage of 4.35 to 3.00V and 0.2C in an environment at a temperature of 25 ℃ and the discharge capacity at this time was defined as C0. Then, CC-CV charging was carried out by a constant current of 0.2C, and discharge was carried out to 2.5V by a constant current of 0.5C in an environment at a temperature of-10 ℃ and the discharge capacity at that time was defined as C1. Then, the capacity retention rate represented by Δ C ═ (C1/C0) × 100 (%) was obtained as a rate characteristic, and evaluated by the following criteria. The larger the value of the capacity retention rate Δ C, the higher the discharge capacity at a high current in a low-temperature environment and the lower the internal resistance.

A: the capacity retention rate Delta C is more than 70%

B: the capacity retention rate Delta C is more than 65 percent and less than 70 percent

C: the capacity retention rate Delta C is more than 60 percent and less than 65 percent

D: the capacity retention rate Delta C is less than 60 percent

< cycle characteristics >

The electrolyte was injected into the lithium ion secondary battery, and the battery was allowed to stand at 25 ℃ for 24 hours. Then, the following charge and discharge operations were performed: the initial capacity C2 was measured by charging to 4.35V at a temperature of 25 ℃ by a constant voltage constant current (CC-CV) method with a 1C charge rate (cut-off condition: 0.02C), and discharging to 3.0V by a Constant Current (CC) method with a 1C discharge rate.

Further, the same charge and discharge operations were repeated in an environment of 45 ℃ to measure a capacity C3 after 300 cycles. Then, the capacity retention rate Δ C ═ C3/C2 × (100) (%) was calculated and evaluated by the following criteria. The higher the value of the capacity retention rate Δ C', the smaller the decrease in discharge capacity, and the more excellent the cycle characteristics.

A: the capacity retention rate DeltaC' is more than 85 percent

B: the capacity retention rate Delta C' is more than 80 percent and less than 85 percent

C: the capacity retention rate Delta C' is more than 75 percent and less than 80 percent

D: the capacity retention rate delta C' is less than 75 percent

(example 1)

< preparation of Binder (Polymer A) >

In a reactor equipped with a stirrer, 70 parts of ion exchange water, 0.15 part of sodium lauryl sulfate (product name "EMAL 2F", manufactured by ltd.) as an emulsifier, and 0.5 part of ammonium persulfate were supplied, and the gas phase part was replaced with nitrogen gas, and the temperature was raised to 60 ℃.

On the other hand, 50 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate as an emulsifier, and 94 parts of N-butyl acrylate as an alkyl (meth) acrylate monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, 2 parts of methacrylic acid as a carboxylic acid group-containing monomer, 1 part of N-methylolacrylamide as a hydroxyl group-containing monomer, and 1 part of allyl glycidyl ether as an epoxy group-containing monomer were mixed in a separate container to obtain a monomer composition. The monomer composition was continuously added to the above reactor over 4 hours to conduct polymerization. During the addition, the reaction was carried out at 60 ℃. After the completion of the addition, the reaction mixture was stirred at 70 ℃ for 3 hours, and then the reaction was terminated to obtain an aqueous dispersion containing a polymer a (water-insoluble) as a binder.

Then, the volume average particle diameter and the glass transition temperature of the obtained binder material were measured. The results are shown in Table 1. The carboxylic acid group content and the nitrile group content of the obtained adhesive material were calculated from the charge amount of methacrylic acid as a carboxylic acid group-containing monomer and the charge amount of acrylonitrile as a nitrile group-containing monomer, respectively. The results are shown in Table 1.

< preparation of slurry composition for functional layer of nonaqueous Secondary Battery >

A slurry composition was prepared by stirring 50 parts (solid component equivalent) of the aqueous dispersion of polymer a, 50 parts of melamine cyanurate a (volume average particle diameter: 190nm) as a melamine compound, 5 parts of a wetting agent (product name "EMULGEN (registered trademark) 120", manufactured by Kao Corporation) and 600 parts of ion-exchanged water for 30 minutes by a multifunctional stirrer (Three-One Motor).

< production of spacer having functional layer >

The slurry composition obtained above was applied to a spacer substrate made of polypropylene (manufactured by Celgard, inc., product name "Celgard (registered trademark) 2500", thickness: 25 μm, microporous membrane), and dried at a temperature of 50 ℃ for 3 minutes to obtain a spacer having a functional layer on one surface of the spacer substrate (thickness of the functional layer: 2 μm). Using the spacer, the adhesion between the functional layer and the spacer base, the permeability of the spacer, and the presence or absence of a dried product of the slurry composition inside the spacer base were evaluated. The results are shown in Table 1.

< preparation of negative electrode >

33.5 parts of 1, 3-butadiene, 3.5 parts of itaconic acid, 62 parts of styrene, 1 part of 2-hydroxyethyl acrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion exchange water and 0.5 part of potassium persulfate as a polymerization initiator were charged into a 5MPa pressure-resistant vessel equipped with a stirrer, and after sufficient stirring, the temperature was raised to 50 ℃ to initiate polymerization. When the polymerization conversion reached 96%, the polymerization reaction was terminated by cooling, and a mixture containing a binder (styrene-butadiene copolymer) in a granular form was obtained.

After a 5% aqueous solution of sodium hydroxide was added to the mixture to adjust the pH to 8, unreacted monomers were removed by heating and distillation under reduced pressure. Then, the mixture was cooled to 30 ℃ or lower to obtain an aqueous dispersion containing the binder for the negative electrode composite layer.

Next, a mixture of 100 parts of artificial graphite (volume average particle diameter: 15.6 μm) as a negative electrode active material and 1 part of a 2% aqueous solution of sodium carboxymethyl cellulose (product name "MAC 350 HC" manufactured by Nippon Paper Industries co., ltd.) as a thickener in terms of solid content equivalent was adjusted to a solid content concentration of 68% with ion-exchanged water, and then mixed at 25 ℃ for 60 minutes. Further, the solid content was adjusted to 62% with ion-exchanged water, and then mixed at 25 ℃ for 15 minutes to obtain a mixed solution. To the obtained mixed solution, 1.5 parts by solid equivalent of the aqueous dispersion containing the binder for a negative electrode composite material layer and ion-exchanged water were added, and the mixture was adjusted so that the final solid content concentration became 52%, and further mixed for 10 minutes. This mixed solution was subjected to defoaming treatment under reduced pressure to obtain a slurry composition for a negative electrode having good fluidity.

The slurry composition for a negative electrode obtained above was applied to one surface of a copper foil (thickness: 20 μm) as a current collector using a notch wheel coater so that the dried film thickness became about 150 μm, and dried. The drying is carried out by transporting the coated copper foil in an oven at 60 ℃ for 2 minutes at a rate of 0.5 m/min. Then, by performing a heating treatment at 120 ℃ for 2 minutes, a negative electrode raw material before pressing was obtained. The anode raw material before pressing was rolled by a roll press to obtain an anode having an anode composite material layer (thickness: 100 μm) on one side of the current collector.

< preparation of Positive electrode >

100 parts of LiCoO as a positive electrode active material₂(volume average particle diameter: 12 μm), 2 parts of acetylene black (product name "HS-100" manufactured by electrochemical Co., Ltd.) as a conductive material, 2 parts of polyvinylidene fluoride (product name "# 7208" manufactured by KUREHA CORPORATION) as a binder for a positive electrode composite layer in terms of solid content equivalent, and N-methylpyrrolidone as a solvent were mixed to obtain a mixed solution in which the total solid content concentration was adjusted to 70%. The obtained mixed solution was mixed by using a planetary mixer to obtain a positive electrode slurry composition.

The slurry composition for a positive electrode obtained above was applied to one surface of an aluminum foil (thickness: 20 μm) as a current collector using a notch wheel coater so that the dried film thickness became about 150 μm, and dried. The drying was carried out by transporting the coated aluminum foil at a rate of 0.5 m/min in an oven at 60 ℃ for 2 minutes. Then, the positive electrode raw material before pressing was obtained by performing heat treatment at 120 ℃ for 2 minutes. The positive electrode raw material before pressing was rolled by a roll press to obtain a positive electrode having a positive electrode composite material layer (thickness: 95 μm) on one surface of a current collector.

< production of Secondary Battery >

As the battery exterior package, an aluminum package material exterior package was prepared. The fabricated positive electrode was cut into a square of 4.6cm × 4.6cm to obtain a rectangular positive electrode. The spacer thus produced was cut into a square of 5.2cm × 5.2cm to obtain a rectangular spacer. Further, the produced negative electrode was cut into a square of 5cm × 5cm to obtain a rectangular negative electrode. The rectangular positive electrode is disposed in the outer package of the aluminum package material so that the surface of the positive electrode on the collector side is in contact with the outer package of the aluminum package material. Then, the rectangular separator is disposed on the surface of the rectangular positive electrode on the positive electrode composite layer side so that the functional layer of the separator is in contact with the rectangular positive electrode. Further, the momentThe positive electrode is disposed on the separator such that the surface on the positive electrode composite layer side faces the separator. Next, an electrolyte solution (a mixed solvent of Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and Vinylene Carbonate (VC) (volume mixing ratio: EC/EMC/VC: 68.5/30/1.5) containing LiPF at a concentration of 1M was injected so that air did not remain therein₆As a solution supporting the electrolyte). Further, the aluminum packaging material was sealed by heat sealing at 150 ℃ to produce a lithium ion secondary battery.

The lithium ion secondary battery was evaluated for rate characteristics and cycle characteristics. The results are shown in Table 1.

(example 2)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 1, except that 300 parts of alumina (product name "AKP 30" manufactured by sumitomo chemical corporation, volume average particle diameter: 300nm) was further used as non-conductive particles in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery. The results are shown in Table 1.

(example 3)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1 except that melamine cyanurate B (volume average particle diameter: 270nm) was used as a melamine compound instead of melamine cyanurate a in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 1.

(example 4)

A slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in example 1 except that a polymer B prepared as follows was used as a binder instead of the polymer a and melamine cyanurate C (volume average particle diameter: 50nm) was used as a melamine compound instead of the melamine cyanurate a in preparing the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 1.

< preparation of Binder (Polymer B) >

300 parts of ion exchange water, 1.5 parts of sodium lauryl sulfate (product name "EMAL 2F", manufactured by ltd.) as an emulsifier, 94 parts of N-butyl acrylate as an alkyl (meth) acrylate monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, 2 parts of methacrylic acid as a carboxylic acid group-containing monomer, 1 part of N-methylolacrylamide as a hydroxyl group-containing monomer, and 1 part of allyl glycidyl ether as an epoxy group-containing monomer were charged into a reactor equipped with a stirrer, and the temperature was raised to 70 ℃. Then, 0.8 part of ammonium persulfate was added thereto and stirred for 2 hours. Then, the reaction was terminated by further stirring at 80 ℃ for 3 hours to obtain an aqueous dispersion containing a polymer B (water-insoluble) as a binder.

(example 5)

A binder, a slurry composition for a non-aqueous secondary battery functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in example 4, except that a separator having a functional layer prepared as follows was used, and various evaluations were performed. The results are shown in Table 1.

< production of spacer having functional layer >

A polyethylene spacer substrate (thickness: 12 μm, air permeability: 100 sec/100 ccAir, microporous membrane) was immersed in the prepared slurry composition for 2 minutes, and then taken out of the slurry composition to scrape off excess slurry composition on the surface. Then, the resultant was dried in an oven at 50 ℃ for 1 minute to fabricate a spacer having functional layers on both sides (thickness of each functional layer on one side: 1 μm). The spacer was used to evaluate the adhesion between the functional layer and the spacer base material, the permeability of the spacer, and the presence or absence of a dried product of the slurry composition inside the spacer base material. The results are shown in Table 1.

(example 6)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 5, except that 300 parts of alumina (product name "AEROXIDE (registered trademark) Alu 65", manufactured by Nippon Aerosil co., ltd., volume average particle diameter: 25nm) was further used as non-conductive particles in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery. The results are shown in Table 1.

(example 7)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1 except that ammeline a (volume average particle diameter: 190nm) was used as a melamine compound instead of melamine cyanurate a in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 1.

(example 8)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 5, except that ammeline B (volume average particle diameter: 50nm) was used as a melamine compound instead of melamine cyanurate C in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery. The results are shown in Table 1.

(example 9)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1 except that melamine a (volume average particle diameter: 190nm) was used as a melamine compound instead of melamine cyanurate a in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 2.

(example 10)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 5 except that melamine B (volume average particle diameter: 50nm) was used as a melamine compound instead of melamine cyanurate C in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 2.

(examples 11 to 12)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in example 1, except that the amounts of the binder and melamine cyanurate a to be added were changed as shown in table 2, respectively, at the time of preparing the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 2.

(example 13)

< preparation of Binder (Polymer C) >

In a reactor equipped with a stirrer, 70 parts of ion exchange water, 0.15 part of sodium lauryl sulfate (product name "EMAL 2F", manufactured by ltd.) as an emulsifier, and 0.5 part of ammonium persulfate were supplied, and the gas phase part was replaced with nitrogen gas, and the temperature was raised to 60 ℃.

On the other hand, 50 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate as an emulsifier, and 94 parts of 2-ethylhexyl acrylate as an alkyl (meth) acrylate monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, 2 parts of methacrylic acid as a carboxylic acid group-containing monomer, 1 part of N-methylolacrylamide as a hydroxyl group-containing monomer, and 1 part of allyl glycidyl ether as an epoxy group-containing monomer were mixed in a separate container to obtain a monomer composition. The monomer composition was continuously added to the above reactor over 4 hours to conduct polymerization. During the addition, the reaction was carried out at 60 ℃. After the completion of the addition, the reaction mixture was stirred at 70 ℃ for 3 hours, and then the reaction was terminated to obtain an aqueous dispersion containing a polymer C (water-insoluble) as a binder.

Then, the volume average particle diameter and the glass transition temperature of the obtained binder material were measured. The results are shown in Table 2. The carboxylic acid group content and the nitrile group content of the obtained adhesive material were calculated from the charge amount of methacrylic acid as a carboxylic acid group-containing monomer and the charge amount of acrylonitrile as a nitrile group-containing monomer, respectively. The results are shown in Table 2.

< preparation of coupling-treated Melamine Compound (coupling-treated Melamine cyanurate A) >

100 parts of melamine cyanurate A and 1.5 parts of gamma-glycidoxypropyltrimethoxysilane as a coupling agent were added to 100 parts of hexane and stirred at room temperature for 30 minutes. After the termination of the stirring, the hexane was removed by drying to obtain a coupling-treated melamine cyanurate A.

< preparation of slurry composition for functional layer of nonaqueous Secondary Battery >

A slurry composition was prepared by stirring 50 parts (solid content equivalent) of an aqueous dispersion of polymer C, 50 parts of coupling-treated melamine cyanurate A (volume average particle diameter: 190nm), 5 parts of a wetting agent (product name "EMULGEN (registered trademark) 120", manufactured by Kao Corporation) and 600 parts of ion-exchanged water for 30 minutes by a multi-function stirrer.

< production of spacer having functional layer >

The slurry composition thus obtained was applied to a polypropylene spacer substrate (made by Japan Vilene Company, Ltd., product name "FT-300", thickness: 160 μm, nonwoven fabric) by means of a gravure coater, and dried at 50 ℃ for 3 minutes to obtain a spacer having a functional layer on one surface of the spacer substrate (thickness of the functional layer: 3 μm). Using the spacer, the adhesion between the functional layer and the spacer base, the permeability of the spacer, and the presence or absence of a dried product of the slurry composition inside the spacer base were evaluated. The results are shown in Table 2.

< production of negative electrode, positive electrode, and Secondary Battery >

A negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1, except that the separator having the functional layer produced in the above manner was used, and various evaluations were performed. The results are shown in Table 2.

(example 14)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 13, except that 300 parts of alumina (product name "AKP 30" manufactured by sumitomo chemical corporation, volume average particle diameter: 300nm) was further used as non-conductive particles in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery. The results are shown in Table 2.

(example 15)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 13 except that 300 parts of alumina (product name "AKP 30" manufactured by sumitomo chemical corporation, volume average particle diameter: 300nm) was used as a non-conductive particle in place of the melamine compound used for the coupling treatment in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery. The results are shown in Table 2.

(example 16)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 13 except that 300 parts of alumina (product name "AKP 30" manufactured by sumitomo chemical corporation, volume average particle diameter: 300nm) as nonconductive particles was used as a melamine compound instead of the coupling treatment melamine cyanurate a in the production of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 2.

< preparation of coupling-treated Melamine Compound (coupling-treated Melamine cyanurate B) >

100 parts of melamine cyanurate B and 1.5 parts of gamma-glycidoxypropyltrimethoxysilane as a coupling agent were added to 100 parts of hexane and stirred at room temperature for 30 minutes. After the termination of the stirring, the hexane was removed by drying to obtain a coupling-treated melamine cyanurate B.

(example 17)

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 13 except that 300 parts of alumina (product name "AKP 30" manufactured by sumitomo chemical corporation, volume average particle diameter: 300nm) as nonconductive particles was used as a melamine compound instead of the coupling treatment melamine cyanurate a in the production of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 3.

< preparation of coupling-treated Melamine Compound (coupling-treated Melamine cyanurate C) >

100 parts of melamine cyanurate C and 1.5 parts of gamma-glycidoxypropyltrimethoxysilane as a coupling agent were added to 100 parts of hexane and stirred at room temperature for 30 minutes. After the termination of the stirring, the hexane was removed by drying to obtain a coupling-treated melamine cyanurate C.

(example 18)

A binder (polymer a) was prepared in the same manner as in example 1. Then, a slurry composition for a non-aqueous secondary battery functional layer, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 13, except that the polymer a was used as a binder instead of the polymer C in the preparation of the slurry composition for a non-aqueous secondary battery functional layer. The results are shown in Table 3.

(example 19)

A binder (polymer a) was prepared in the same manner as in example 1. Then, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 13 except that, in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, the polymer a was used as a binder instead of the polymer C, and the melamine cyanurate a was used as a melamine compound instead of the coupling treatment of the melamine cyanurate a, and various evaluations were performed. The results are shown in Table 3.

(example 20)

A slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared and evaluated in the same manner as in example 13 except that a cellulose separator substrate (product name "CELISH KY-100G", manufactured by Daicel Corporation, thickness: 20 μm, nonwoven fabric) was used instead of the polypropylene separator substrate in the preparation of a separator having a functional layer. The results are shown in Table 3.

(example 21)

A slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in example 13 except that a polyester separator substrate (product name "PURELY" manufactured by AWA PAPER & tecnologic composition, inc., thickness: 30 μm, nonwoven fabric) was used instead of the polypropylene separator substrate to prepare a separator having a functional layer, and various evaluations were performed. The results are shown in Table 3.

Comparative example 1

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1 except that the amount of the binder (polymer a) was changed to 100 parts without using melamine cyanurate in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 3.

Comparative example 2

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 5 except that the amount of the binder (polymer B) was changed to 100 parts without using melamine cyanurate C in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 3.

Comparative example 3

A binder, a slurry composition for a functional layer of a nonaqueous secondary battery, a separator having a functional layer, a negative electrode, a positive electrode, and a secondary battery were produced in the same manner as in example 1 except that melamine cyanurate D (volume average particle diameter: 1000nm) was used as a melamine compound instead of melamine cyanurate a in the preparation of the slurry composition for a functional layer of a nonaqueous secondary battery, and various evaluations were performed. The results are shown in Table 3.

In tables 1 to 3 shown below,

"PP" represents a polypropylene spacer base material,

"PE" represents a polyethylene spacer base material,

"CE" represents a cellulose spacer base material,

"PEs" represents a spacer base material made of polyester.

[ Table 1]

[ Table 2]

[ Table 3]

As is clear from tables 1 to 3, in examples 1 to 21 in which the slurry compositions containing the binder having a predetermined functional group and the melamine compound having a volume average particle diameter within a predetermined range were used and the amount of the melamine compound in the total of the binder and the melamine compound was within a predetermined range, the spacers having a strong adhesion between the functional layer and the spacer base and excellent permeability could be produced. Further, it is found that the use of the separator allows the secondary battery to exhibit excellent rate characteristics and cycle characteristics.

On the other hand, as is clear from table 3, in comparative examples 1 to 2 using the adhesive composition containing the adhesive material but not containing the melamine compound, the functional layer of the spacer and the spacer base material could not be firmly adhered, and the permeability of the spacer was also reduced. It is also found that the use of the separator does not allow the secondary battery to exhibit excellent rate characteristics and cycle characteristics.

Further, as is clear from table 3, in comparative example 3 using a melamine compound having a volume average particle diameter exceeding a predetermined value, the functional layer of the separator and the separator base material could not be firmly adhered, and the secondary battery could not exhibit excellent rate characteristics and cycle characteristics even if the separator was used.

Industrial applicability

According to the present invention, it is possible to provide a slurry composition for a functional layer of a nonaqueous secondary battery, which can form a functional layer that can be firmly adhered to a spacer base material and can improve the rate characteristics of a nonaqueous secondary battery using a spacer having the functional layer.

Further, according to the present invention, it is possible to provide a separator for a nonaqueous secondary battery, in which a functional layer and a separator base are firmly adhered to each other and a nonaqueous secondary battery can exhibit excellent rate characteristics.

Further, according to the present invention, a nonaqueous secondary battery having excellent rate characteristics can be provided.