KR102007592B1 - Separator / interlayer laminate, structure for nonaqueous electrolyte secondary battery, and aqueous latex - Google Patents

Abstract

The separator / intermediate layer laminate according to the present invention has a separator for a nonaqueous electrolyte secondary battery and an intermediate layer provided on at least one main surface of the separator, wherein the intermediate layer is a structural unit derived from (A) unsaturated dibasic acid salt and / or unsaturated dichloride. The polymer particle containing the copolymer containing the structural unit derived from a monoacid ester and the structural unit derived from a vinylidene fluoride-type monomer, and (B) inorganic particle are included.

Description

Separator / interlayer laminate, structure for nonaqueous electrolyte secondary battery, and aqueous latex

The present invention relates to a separator / interlayer laminate, a structure for nonaqueous electrolyte secondary batteries, and an aqueous latex.

Recent advances in electronic technology are surprising, and various devices have become smaller and lighter. In addition to miniaturization and weight reduction of the electronic device, miniaturization and weight reduction of the battery serving as the power source thereof are required. As a battery capable of obtaining large energy in a small volume and mass, a nonaqueous electrolyte secondary battery using lithium is used. In addition, the use of nonaqueous electrolyte secondary batteries as energy sources such as hybrid cars and electric vehicles has been proposed, and practical use has begun.

As the use of the nonaqueous electrolyte secondary battery has been expanded to tablet terminals, smartphones, automobiles, etc., the capacity and large area of the nonaqueous electrolyte secondary batteries have also been required. For example, Patent Literature 1 discloses a nonaqueous electrolyte secondary battery having a stacked electrode body in which a large area of the positive electrode plate and the negative electrode plate are laminated with a separator interposed therebetween and a specific nonaqueous electrolyte.

Patent Document 1: Japanese Unexamined Patent Publication No. 2013-206724

The nonaqueous electrolyte secondary battery structure usually has a positive electrode and a negative electrode, and a separator for insulating the positive electrode and the negative electrode is disposed therebetween. In a structure for a nonaqueous electrolyte secondary battery having a large area for achieving a large capacity, a laminate including a positive electrode, a separator, and a negative electrode is misaligned between the positive electrode and the separator and / or between the negative electrode and the separator even by distortion by a very small external force. Peeling tends to occur and the part which does not contribute to charging and discharging is easy to show. As a result, there is a possibility that it is difficult to obtain a desired capacity. Therefore, there is a need for a nonaqueous electrolyte secondary battery structure in which the positive electrode and the separators and the negative electrode and the separators are firmly in close contact with each other so that such misalignment and peeling are unlikely to occur.

In addition, in order to achieve a large capacity, it is very important to secure safety in a large-area nonaqueous electrolyte secondary battery structure. Since olefin separators used in general are thermally shrunk by heating at a temperature of 100 ° C. or more, in a structure for a large-area nonaqueous electrolyte secondary battery, when such an olefin separator is used, there is a problem of causing a short circuit between the positive electrode and the negative electrode. have.

The present invention uses a separator / middle layer laminate having a small area shrinkage during heating of the separator, and a separator / middle layer laminate, wherein at least one of the positive electrode and the separator and the negative electrode and the separator are firmly adhered to each other. It is an object to provide a battery structure and an aqueous latex used to obtain the structure for nonaqueous electrolyte secondary batteries.

MEANS TO SOLVE THE PROBLEM In order to achieve the said subject, as a result of earnest research, (A) the structural unit derived from unsaturated dibasic acid and / or the structural unit derived from unsaturated dibasic acid monoester, and the vinylidene fluoride-type monomer derived from It was found out that the above problems can be achieved by combining a polymer particle containing a copolymer containing a structural unit and an inorganic particle (B), thereby completing the present invention.

That is, the separator / middle layer laminated body which concerns on this invention has a separator for nonaqueous electrolyte secondary batteries, and the intermediate | middle layer provided in the at least one main surface of the said separator,

The said intermediate | middle layer contains the polymer particle containing the copolymer containing the structural unit derived from (A) unsaturated dibasic acid, and / or the structural unit derived from unsaturated dibasic acid monoester, and the vinylidene fluoride-type monomer, and (B) It contains an inorganic particle.

With respect to the polymer particles, the 1740 absorbance of an infrared absorption spectrum at _{1740 cm-1} and A ^-1 cm ratio _{A 1740 cm-1 / A 3020} cm _{3020 cm-1} of the absorbance A of the infrared absorption spectrum at 3020 cm ^-1 It is preferable that _-1 is 0.10 or more.

It is preferable that the average particle diameter of the said polymer particle is 50 nm or more and 700 nm or less.

It is preferable that the said polymer particle is manufactured by emulsion polymerization.

The nonaqueous electrolyte secondary battery structure according to the present invention has a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode,

The nonaqueous electrolyte secondary battery structure has an intermediate layer between at least one of the positive electrode and the separator and between the negative electrode and the separator,

The said intermediate | middle layer contains the polymer particle containing the copolymer containing the structural unit derived from (A) unsaturated dibasic acid, and / or the structural unit derived from unsaturated dibasic acid monoester, and the vinylidene fluoride-type monomer, and (B) It contains an inorganic particle.

The aqueous latex according to the present invention is an aqueous latex comprising polymer particles and inorganic particles dispersed in water,

The polymer particles contain a copolymer comprising a structural unit derived from an unsaturated dibasic acid and / or a structural unit derived from an unsaturated dibasic acid monoester and a structural unit derived from a vinylidene fluoride monomer,

A nonaqueous electrolyte secondary battery structure having a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode, which is used for producing an intermediate layer provided between at least one of the positive electrode and the separator and between the negative electrode and the separator. do.

Advantageous Effects of Invention According to the present invention, a separator / middle layer laminate having a small area shrinkage rate at the time of separator heating and a nonaqueous material in which at least one of the anode and the separator and the cathode and the separator are firmly adhered to each other using the separator / middle layer laminate. The structure for electrolyte secondary batteries and the aqueous latex used for obtaining the structure for nonaqueous electrolyte secondary batteries can be provided. According to the structure for a nonaqueous electrolyte secondary battery according to the present invention, it is possible to efficiently and effectively achieve a large capacity and a large area of the nonaqueous electrolyte secondary battery.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the graph obtained by performing IR spectral measurement with respect to the powder derived from aqueous latex obtained in the Example or the comparative example.

<Aqueous latex>

The aqueous latex according to the present invention comprises polymer particles and inorganic particles dispersed in water, wherein the polymer particles are structural units derived from unsaturated dibasic acids and / or structural units derived from unsaturated dibasic acid monoesters and vinylidene fluoride series. A copolymer containing a structural unit derived from a monomer, wherein the aqueous latex is a nonaqueous electrolyte secondary battery structure having a positive electrode, a negative electrode, and a separator laminated between the positive electrode and the negative electrode, between the positive electrode and the separator, and the negative electrode and It is used in manufacture of an intermediate | middle layer provided in at least one among separators. In aqueous latex, each of the polymer particles and the inorganic particles may be used alone or in combination of two or more thereof.

[Polymer particle]

The polymer particles contain a copolymer comprising a structural unit derived from an unsaturated dibasic acid and / or a structural unit derived from an unsaturated dibasic acid monoester and a structural unit derived from a vinylidene fluoride monomer. The copolymer exhibits a polar interaction attributable to the carbonyl group of the structural unit derived from the unsaturated dibasic acid and / or the structural unit derived from the unsaturated dibasic acid monoester, and is excellent in adhesion to the substrate. Therefore, in the structure for a nonaqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a separator laminated between the positive electrode and the negative electrode, a copolymer is included in the production of an intermediate layer provided between at least one of the positive electrode and the separator and between the negative electrode and the separator. When the aqueous latex according to the present invention containing the polymer particles is used, the adhesive strength between the separator and the intermediate layer, the adhesive strength between the positive electrode and the intermediate layer, and the adhesive strength between the negative electrode and the intermediate layer tend to be excellent. In the polymer particles, the copolymers may be used alone or in combination of two or more thereof.

As unsaturated dibasic acid, it is preferable that it is C5-C8. As unsaturated dibasic acid, unsaturated dicarboxylic acid is mentioned, for example, More specifically, maleic anhydride, a citraconic acid, etc. are mentioned.

As unsaturated dibasic acid monoester, it is preferable that it is C5-C8. Examples of the unsaturated dibasic acid monoesters include unsaturated dicarboxylic acid monoesters, and more specifically, maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester, and citraconic acid monoethyl ester. Can be mentioned. An unsaturated dibasic acid monoester can be used individually, or can be used in combination of 2 or more type.

Examples of the vinylidene fluoride monomers include vinylidene fluoride, vinyl fluoride, trifluoroethylene (TrFE), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and the like. Can be mentioned. The vinylidene fluoride monomers may be used alone or in combination of two or more thereof.

In the copolymer, the molar ratio of vinylidene fluoride and other vinylidene fluoride monomers, in particular the vinylidene fluoride monomer, is a combination of vinylidene fluoride with hexafluoropropylene, tetrafluoroethylene, and / or chlorotrifluoroethylene. In the case of, the molar ratio of vinylidene fluoride and hexafluoropropylene, tetrafluoroethylene, and / or chlorotrifluoroethylene is preferably 100: 0 to 80:20, and more preferably 99.5: 0.5 to 85:15 More preferably, they are 99: 1-90:10.

The copolymer may also include structural units derived from monomers other than unsaturated dibasic acids, unsaturated dibasic acid monoesters and vinylidene fluoride monomers (hereinafter also referred to as other monomers). Although there is no limitation in particular as another monomer, For example, the fluorine-type monomer copolymerizable with a vinylidene fluoride-type monomer; Hydrocarbon-type monomers, such as ethylene and propylene; Aromatic vinyl compounds, such as styrene and (alpha) -methylstyrene; (meth) acrylonitrile, etc. Unsaturated nitrile compound; acrylic acid ester compound; acrylamide compound; epoxy group-containing unsaturated compound such as glycidyl methacrylate; sulfone group-containing unsaturated compound such as vinyl sulfonic acid; carboxyl groups other than unsaturated dibasic acid and unsaturated dibasic acid monoester Containing monomer; A carboxylic acid anhydride group containing monomer is mentioned. Another monomer may be used independently and may be used in combination of 2 or more type.

In the copolymer, the total content of the structural unit derived from the unsaturated dibasic acid and the structural unit derived from the unsaturated dibasic acid monoester is preferably 0.02 mol% or more and 5.0 mol% or less based on 100 mol% of the total structural units. More preferably, they are 0.05 mol% or more and 4.0 mol% or less, More preferably, they are 0.07 mol% or more and 3.0 mol% or less, Most preferably, they are 0.1 mol% or more and 2.0 mol% or less.

In the copolymer, the content of the structural unit derived from the vinylidene fluoride monomer is preferably 50 mol% or more and 99.98 mol% or less, more preferably 80 mol% or more, based on 100 mol% of the total structural units. It is 99.95 mol% or less, More preferably, it is 85 mol% or more and 99.93 mol% or less, Most preferably, it is 90 mol% or more and 99.9 mol% or less. In particular, when a copolymer consists of a structural unit derived from an unsaturated dibasic acid, and / or a structural unit derived from an unsaturated dibasic acid monoester, and a structural unit derived from a vinylidene fluoride-type monomer, a vinylidene fluoride system in a copolymer The content of the structural unit derived from the monomer is preferably 95.0 mol% or more and 99.98 mol% or less, more preferably 96.0 mol% or more and 99.95 mol% or less, and even more preferably 100 mol% of the total structural units. Preferably it is 97.0 mol% or more and 99.93 mol% or less, Most preferably, it is 98.0 mol% or more and 99.9 mol% or less. In addition, when a copolymer consists of a structural unit derived from an unsaturated dibasic acid, and / or a structural unit derived from an unsaturated dibasic acid monoester, and a structural unit derived from a vinylidene fluoride-type monomer, in a copolymer, The content of the structural unit derived from the vinylidene-based monomer is preferably 50 mol% or more and 98.98 mol% or less, more preferably 80 mol% or more and 97.95 mol% or less, based on 100 mol% of the total structural units. Still more preferably, it is 85 mol% or more and 96.93 mol% or less, Most preferably, it is 90 mol% or more and 95.9 mol% or less.

When a copolymer contains another monomer, content of the structural unit derived from another monomer in a copolymer becomes like this. Preferably it is 1.0 mol% or more and 49.98 mol% or less with respect to a total of 100 mol% of all the structural units, Preferably they are 2.0 mol% or more and 19.95 mol% or less, More preferably, they are 3.0 mol% or more and 14.93 mol% or less, Most preferably, they are 4.0 mol% or more and 9.9 mol% or less.

As said fluorine-type monomer copolymerizable with a vinylidene fluoride-type monomer, the perfluoroalkyl vinyl ether represented by perfluoromethyl vinyl ether, etc. are mentioned.

As carboxyl group-containing monomers other than unsaturated dibasic acid and unsaturated dibasic acid monoester, unsaturated monobasic acid etc. are preferable. Examples of the unsaturated monobasic acid include acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, and the like. Especially, as carboxyl group-containing monomers other than unsaturated dibasic acid and unsaturated dibasic acid monoester, acrylic acid and methacrylic acid are preferable. As carboxyl group-containing monomers other than unsaturated dibasic acids and unsaturated dibasic acid monoesters, acryloyloxyethyl succinic acid, methacryloyloxyethyl succinic acid, acryloyloxyethyl phthalic acid, methacryloyloxyethyl phthalic acid, acrylo Iloxypropyl succinic acid etc. can also be used.

As a copolymer used by this invention, you may use a crosslinked copolymer. When using a crosslinked thing as a copolymer, a polyfunctional monomer may be used as another monomer, and after obtaining an uncrosslinked polymer, a crosslinking reaction may be performed using a polyfunctional monomer.

The copolymer may be a structural unit derived from an unsaturated dibasic acid and / or a structural unit derived from an unsaturated dibasic acid monoester, a structural unit derived from a vinylidene fluoride monomer, and the fluorine monomer copolymerizable with the vinylidene fluoride monomer. Copolymers containing the derived structural unit are preferable, and specifically, vinylidene fluoride (VDF) -TFE-maleic acid monomethyl ester (MMM) copolymer, VDF-TFE-HFP-MMM copolymer, and VDF-HFP- MMM copolymer, VDF-CTFE-MMM copolymer, VDF-TFE-CTFE-MMM copolymer, VDF-HFP-CTFE-MMM copolymer are preferable, and VDF-TFE-HFP-MMM copolymer, VDF-HFP-MMM Copolymers, VDF-CTFE-MMM copolymers, and VDF-HFP-CTFE-MMM copolymers are more preferable.

There is no restriction | limiting in particular as a method of obtaining a copolymer, For example, emulsion polymerization, soap-free emulsion polymerization, miniemulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization Polymerization methods, such as these, are mentioned. Among these, the polymerization method which can obtain a copolymer as particle | grains is preferable. When a copolymer is obtained by shapes other than particle | grains, processing, such as grinding | pulverization, is needed so that it can use as a polymer particle. Therefore, as mentioned above, it is preferable to employ | adopt the method which can obtain a particulate copolymer, ie, polymer particle containing a copolymer.

As a method of obtaining a polymer particle, emulsion polymerization, soap free emulsion polymerization, miniemulsion polymerization, suspension polymerization are mentioned, for example, Emulsion polymerization, soap free emulsion polymerization, which is easy to obtain polymer particle whose average particle diameter is 1 micrometer or less, Miniemulsion polymerization is preferred, and emulsion polymerization is particularly preferred.

The emulsifier (hereinafter also referred to as a surfactant) used when dispersing the particles obtained by the production of copolymerization, suspension polymerization, or the like in water, and the dispersant have good oxidation-reduction resistance in consideration of remaining in the battery. desirable. The aqueous latex according to the present invention may comprise components added in the process of obtaining the polymer particles, for example emulsifiers, dispersants and the like.

The said surfactant may be any of a nonionic surfactant, a cationic surfactant, an anionic surfactant, and an amphoteric surfactant, and may be a some kind. The surfactant used in the polymerization is preferably used conventionally for the polymerization of polyvinylidene fluoride, such as perfluorinated, partially fluorinated, and non-fluorinated surfactants. As an anionic surfactant, a higher alcohol sulfate ester sodium salt, the alkylbenzene sulfonate salt, the dialkyl ester sulfonate salt, the alkyl diphenyl ether disulfonate salt, the polyoxyethylene alkyl ether sodium sulfate salt, polyoxy, for example Ethylene alkyl phenyl ether sodium sulfate salt and the like. Among these, sodium lauryl sulfate ester sodium salt, sodium dodecyl benzene sulfonate salt, polyoxyethylene alkyl ether sodium sulfate salt, polyoxyethylene alkyl phenyl ether sodium sulfate salt, etc. are preferable. Examples of the nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. Examples of the amphoteric active agent include lauryl betaine, hydroxyethyl imidazoline sulfate sodium salt, and imidazoline sulfonic acid sodium salt. Examples of the cationic surfactant include alkylpyridinium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkyldimethylbenzylammonium chloride, and the like. As the fluorine-based surfactant, perfluoroalkylsulfonic acid and salts thereof, pafluoroalkylcarboxylic acid and salts thereof, perfluoroalkyl phosphate esters, perfluoroalkylpolyoxyethylene, perfluoroalkylbetaine, fluorocarbon chains or And fluorine-based surfactants having a fluoropolyether chain. It is preferable to use a fluorine-type surfactant among them.

Moreover, as said reactive emulsifier, polyoxyalkylene alkenyl ether, sodium alkyl allyl sulfosuccinate, sodium methacryloyloxy polyoxypropylene sulfate ester, alkoxy polyethylene glycol methacrylate, sodium styrene sulfonate salt, sodium allyl alkyl sulfonate, etc. But it is not limited to them.

It does not specifically limit as a dispersing agent, A conventionally well-known thing can be used, For example, a fluorine-type dispersing agent is mentioned.

Polymerization conditions, such as polymerization temperature at the time of superposing | polymerizing by each polymerization method mentioned above, can also be set arbitrarily.

With respect to the polymer particles, the 1740 absorbance of an infrared absorption spectrum at _{1740 cm-1} and A ^-1 cm absorbance of the infrared absorption spectrum at _{3020 cm} ^-1 A 3020 _{cm-1 1740 cm-1} ratio A / A's _{3020 cm-} It is preferable that ₁ is 0.10 or more. Absorption at 1740 cm ⁻¹ is due to the group represented by —CO—O—, and absorption at 3020 cm ⁻¹ is due to the group represented by —CH ₂ —. In the copolymer, the group represented by -CO-O- is contained in the structural unit derived from unsaturated dibasic acid and / or the structural unit derived from unsaturated dibasic acid monoester, and the group represented by -CH ₂ -is the entire structural unit The ratio A _{1740 cm −1} / A _{3020 cm −1} reflects the total ratio of the structural units derived from unsaturated dibasic acids and the structural units derived from unsaturated dibasic monoesters among all the structural units in the copolymer. have.

The lower limit of the ratio A _{1740 cm −1} / A _{3020 cm −1} is more preferably 0.12 or more, and still more preferably 0.15 or more. When the said lower limit is in the said range, it is easy to obtain the copolymer containing the structural unit derived from unsaturated dibasic acid and / or the structural unit derived from unsaturated dibasic acid monoester sufficiently. Therefore, in the structure for a nonaqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode, in the production of an intermediate layer provided between at least one of the positive electrode and the separator, and between the negative electrode and the separator, according to the present invention, When aqueous latex is used, it is easy to be excellent in the adhesive strength of a separator and an intermediate | middle layer, the adhesive strength of an anode and an intermediate | middle layer, and the adhesive strength of a cathode and an intermediate | middle layer.

The upper limit of the ratio A _{1740 cm −1} / A _{3020 cm −1} is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. If the upper limit is within the above range, it is not necessary to add an excess of unsaturated dibasic acid and / or unsaturated dibasic acid monoester during the preparation of the copolymer, so that it is possible to obtain the copolymer even when the polymerization initiator is not used excessively. It is easy. As a result, the amount of the polymerization initiator incorporated into the aqueous latex according to the present invention can be effectively reduced, and the properties of the resulting nonaqueous electrolyte secondary battery are hardly impaired.

It is preferable that the minimum of the average particle diameter of the polymer particle used for this invention is 50 nm or more, It is more preferable that it is 100 nm or more, It is further more preferable that it is 150 nm or more. When the said lower limit is in the said range, since the gas permeability of the intermediate | middle layer manufactured using the aqueous latex which concerns on this invention, or the air permeability of the laminated body of an intermediate | middle layer and a separator are easy to be adjusted, it is preferable.

It is preferable that the upper limit of the average particle diameter of the polymer particle used by this invention is 700 nm or less, It is more preferable that it is 600 nm or less, It is further more preferable that it is 500 nm or less. If the upper limit is in the above range, it is preferable because it is easy to control the thickness of the intermediate layer produced using the aqueous latex according to the present invention.

In addition, the said average particle diameter is a cumulant average particle diameter calculated | required by the dynamic light scattering method, and is measured using ELSZ-2 (made by Otsuka Denshi).

[Inorganic particle]

As the inorganic particles, in the nonaqueous electrolyte secondary battery, an inorganic filler or the like conventionally used when providing a resin film (intermediate layer) between a positive electrode or a negative electrode and a separator can be used without limitation. An inorganic particle is a thermally stable component normally, and when an intermediate | middle layer contains such an inorganic particle, it is thought that the separator / intermediate | middle layer laminated body which concerns on this invention is easy to maintain shape, and the area shrinkage rate at the time of separator heating becomes small.

Examples of the inorganic particles include SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , SiC, clay minerals, mica, calcium carbonate and the like. . As an inorganic particle, you may use 1 type individually or 2 or more types.

As the inorganic particles, Al ₂ O ₃ , MgO, and ZnO are preferable from the viewpoint of battery safety and plating solution stability, and Al ₂ O ₃ is more preferable from the viewpoint of insulation and electrochemical stability.

As average particle diameter of an inorganic particle, 5 nm-2 micrometers are preferable, and 10 nm-1 micrometer are more preferable.

A commercial item can also be used as an inorganic particle used by this invention. For example, AKP3000, AKP50 (all of which are manufactured by Sumitomo Kagaku), or the like can be used as the high-purity alumina particles.

And since aqueous latex contains the inorganic particle which is a component with high specific gravity, it is preferable to use for formation of a particle containing layer quickly after preparation, or to redisperse beforehand.

〔Etc〕

The aqueous latex according to the present invention may be composed of polymer particles, inorganic particles, and water, but may also include polymer particles, inorganic particles, and components other than water (hereinafter, also referred to as other components).

Examples of the other component include a water-soluble polymer, an organic filler, a crosslinking agent, and the like. It is preferable to use a water-soluble polymer from the viewpoint of adhering the adhesive between the intermediate layer and the separator, the adhesive between the intermediate layer and the electrode, and the polymer particles in contact with each other. The other component may be dissolved in the aqueous latex according to the invention or may be dispersed. For example, when a water-soluble polymer is used as another component, the water-soluble polymer is usually dissolved in aqueous latex. For example, when an organic filler is used as another component, the organic filler is dispersed in aqueous latex.

As a water-soluble polymer, the polymer which has adhesiveness with respect to a polymer particle, an inorganic particle, an electrode, and a separator is preferable. As the water-soluble polymer, for example, cellulose compounds such as carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose, hydroxyethyl cellulose, diacetyl cellulose and polycarboxylic acids such as ammonium salts or alkali metal salts and polyacrylic acid (PAA) and their Alkali metal salt, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene oxide (PEO), etc. are mentioned, and carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), etc. are used for a long term. It is preferable from a viewpoint of a poem.

Examples of the organic filler include styrene-butadiene rubber, acrylate-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, Ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylate, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, The thing containing a polyester resin, an acrylic resin, a phenol resin, an epoxy resin, etc. are mentioned.

The aqueous latex according to the present invention may contain a nonaqueous medium in addition to water, in view of improving its applicability. Examples of the nonaqueous medium include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, sulfone compounds, and the like, and one or more selected from these can be used. When using a non-aqueous medium, a small amount may be sufficient as it, Specifically, with respect to the whole aqueous latex, Preferably it is 30 mass% or less, More preferably, it is 10 mass% or less, More preferably, it is 5 mass% or less to be.

In the aqueous latex according to the present invention, the content of the polymer particles and the inorganic particles is preferably 60 to 100 parts by mass, more preferably 65 to 100 parts by mass, and more preferably 70 to 100 parts by mass in 100 parts by mass of components other than water. Even more preferred.

Moreover, it is preferable that it is 1: 99-99: 1, and, as for the mass ratio of a polymer particle and an inorganic particle, it is 2: 98-70: 30 from a viewpoint of adhesiveness with respect to an electrode, and heat shrinkage resistance, and 5: 95- It is more preferable that it is 60:40.

The intermediate layer produced using the aqueous latex according to the present invention comprises polymer particles containing a copolymer and the inorganic particles. Therefore, by using the aqueous latex according to the present invention, it is possible to form an intermediate layer having air permeability, and in the obtained nonaqueous electrolyte secondary battery, the separator or the polymer particles forming the intermediate layer are exposed to high temperatures such as melting. Also in this case, when the inorganic particles are present in the intermediate layer, the effect of improving safety such as short circuit prevention can be expected.

Moreover, when using a water-soluble polymer, content of water-soluble polymer is in 100 mass parts of components other than the water of the aqueous latex which concerns on this invention, Preferably it is 0.01-20 mass parts, More preferably, it is 0.01-15 mass parts. Especially preferably, it is 0.01-10 mass parts.

In the case of using an organic filler, the content of the organic filler is preferably 0.01 to 40 parts by mass, more preferably 0.01 to 35 parts by mass in 100 parts by mass of components other than water of the aqueous latex according to the present invention. Especially preferably, it is 0.01-30 mass parts.

Moreover, in the aqueous latex which concerns on this invention, when the whole aqueous latex is 100 mass parts, content of the water which is a dispersion medium becomes like this. Preferably it is 30-99 mass parts, More preferably, it is 35-98 mass parts. When content is in the said range, it will be easy to be excellent in the applicability | paintability at the time of apply | coating the aqueous latex which concerns on this invention to base materials, such as a positive electrode, a negative electrode, and a separator.

The polymer particles and the inorganic particles can be similarly used not only for the aqueous latex according to the present invention but also for the separator / middle layer laminate according to the present invention and the structure for nonaqueous electrolyte secondary batteries according to the present invention.

The aqueous latex according to the present invention is a nonaqueous electrolyte secondary battery structure having a positive electrode, a negative electrode, and a separator stacked between a positive electrode and a negative electrode, in the production of an intermediate layer provided between at least one of the positive electrode and the separator, and between the negative electrode and the separator. Used. A positive electrode, a negative electrode, a separator, the structure for nonaqueous electrolyte secondary batteries, and an intermediate | middle layer are as mentioned later.

<Structure for nonaqueous electrolyte secondary battery>

The nonaqueous electrolyte secondary battery structure according to the present invention has a positive electrode, a negative electrode, and a separator laminated between the positive electrode and the negative electrode, the nonaqueous electrolyte secondary battery structure has an intermediate layer between at least one of the positive electrode and the separator, and between the negative electrode and the separator. The intermediate layer comprises (A) a polymer particle containing a copolymer comprising a structural unit derived from an unsaturated dibasic acid and / or a structural unit derived from an unsaturated dibasic acid monoester and a structural unit derived from a vinylidene fluoride monomer, and (B) It contains an inorganic particle.

The structure of the nonaqueous electrolyte secondary battery structure according to the present invention is a conventional nonaqueous except that the intermediate layer prepared by using the aqueous latex according to the present invention is provided on at least one of the anode and the separator, and between the cathode and the separator. It is the same as the structure for electrolyte secondary batteries. As a positive electrode, a separator, and a negative electrode, if it is possible to comprise the structure for nonaqueous electrolyte secondary batteries, including a well-known thing, it can use without a restriction | limiting. In the nonaqueous electrolyte secondary battery structure, the positive electrode, the negative electrode, and / or the separator and the intermediate layer may be in direct contact with each other, and another layer may be interposed between the positive electrode, the negative electrode, and / or the separator and the intermediate layer. From the viewpoint of the adhesive strength, the adhesive strength of the negative electrode and the intermediate layer, and the adhesive strength of the separator and the intermediate layer, it is preferable that the positive electrode and the intermediate layer are in direct contact, the negative electrode and the intermediate layer are in direct contact, and the separator and the intermediate layer are in direct contact with each other.

In addition, in this specification, a positive electrode and a negative electrode may be collectively described as an "electrode", and a positive electrode current collector and a negative electrode current collector may be collectively described as "a current collector."

〔anode〕

The positive electrode of the nonaqueous electrolyte secondary battery structure according to the present invention is not particularly limited as long as it has a positive electrode active material that is responsible for the positive electrode reaction and has a current collector function, but in many cases, a positive electrode mixture layer containing the positive electrode active material and a current collector It consists of a positive electrode current collector which functions as a function and also maintains a positive electrode mixture layer.

When the structure for nonaqueous electrolyte secondary batteries according to the present invention has an intermediate layer produced using the aqueous latex according to the present invention between the positive electrode and the separator, the intermediate layer is preferably disposed between the positive electrode mixture layer and the separator. .

The positive electrode current collector is not particularly limited as long as it has good conductivity so that electricity can be supplied to the outside of the secondary battery and does not interfere with the electrode reaction in the secondary battery.

As a positive electrode collector, what is generally used as a positive electrode collector of nonaqueous electrolyte secondary batteries, such as a lithium ion secondary battery, is mentioned.

[Separator]

The separator which the structure for nonaqueous electrolyte secondary batteries which concerns on this invention has is not specifically limited.

The separator used in the present invention is a separator constituting the structure for the nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery obtained from the structure, the separator serves to electrically insulate the positive electrode and the negative electrode and to maintain the electrolyte solution. Although it does not specifically limit as a separator used by this invention, For example, a polyolefin type polymer (for example, polyethylene, a polypropylene, etc.), a polyester type polymer (for example, polyethylene terephthalate, etc.), a polyimide polymer ( For example, aromatic polyamide-based polymer, polyetherimide, etc.), polyethersulfone, polysulfone, polyetherketone, polystyrene, polyethylene oxide, polycarbonate, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, Single layer or multilayer porous membranes, nonwoven fabrics, glass, paper, etc. which consist of ceramics and at least 2 types of these are mentioned. And the modified polymer can also be used as the above-mentioned polymer.

In particular, it is preferable to use the porous membrane of a polyolefin type polymer (for example, polyethylene, a polypropylene, etc.). As the polyolefin-based polymer porous membrane, for example, a single layer polypropylene separator, a single layer polyethylene separator, and a polypropylene / polyethylene / polypropylene 3 which are commercially available from Polypores Co., Ltd. under the trade names of celgard®. A layer separator etc. are mentioned. In addition, the separator may be surface-treated, and the layer of inorganic particle may be previously coated.

In addition, the separator is preferably larger than the positive electrode and the negative electrode in order to ensure insulation between the positive electrode and the negative electrode.

〔cathode〕

The negative electrode of the nonaqueous electrolyte secondary battery structure according to the present invention is not particularly limited as long as it has a negative electrode active material that is responsible for the negative electrode reaction and has a current collector function, but in many cases, functions as a negative electrode mixture layer and a current collector containing the negative electrode active material. At the same time it is made of a negative electrode current collector that serves to maintain the negative electrode mixture layer.

When the structure for nonaqueous electrolyte secondary batteries according to the present invention has an intermediate layer produced using the aqueous latex according to the present invention between the negative electrode and the separator, the intermediate layer is preferably disposed between the negative electrode mixture layer and the separator.

In the present invention, the method for producing a negative electrode comprising the negative electrode current collector and the negative electrode mixture layer is not particularly limited, and for example, the negative electrode mixture containing each component constituting the negative electrode mixture layer is preferably at least one side of the current collector. The method of obtaining a negative electrode by apply | coating to both surfaces and drying the apply | coated negative mix is mentioned.

[Middle floor]

The nonaqueous electrolyte secondary battery structure according to the present invention has an intermediate layer produced using the aqueous latex according to the present invention between at least one of the positive electrode and the separator and between the negative electrode and the separator.

The nonaqueous electrolyte secondary potential structure according to the present invention has an intermediate layer prepared using the aqueous latex according to the present invention at least one of the anode and the separator, and between the cathode and the separator, but the intermediate layer between the anode and the separator, It is preferable to have it between a cathode and a separator. When the nonaqueous electrolyte secondary potential structure according to the present invention has an intermediate layer prepared between the positive electrode and the separator using the aqueous latex according to the present invention, the adhesive strength between the positive electrode and the intermediate layer is easily improved, and the redox resistance of the separator is improved. It is preferable because it improves. In addition, when the nonaqueous electrolyte secondary potential structure according to the present invention has an intermediate layer prepared using the aqueous latex according to the present invention between the negative electrode and the separator, the adhesive strength between the negative electrode and the intermediate layer is likely to be improved.

The thickness of the intermediate layer is preferably 0.2 to 25 µm, more preferably 0.5 to 5 µm.

The intermediate layer is formed mainly from polymer particles and inorganic particles. When SEM observation is performed with respect to an intermediate | middle layer, it is preferable that it can confirm that a polymer particle exists in the state which maintained the particle shape. That is, in the structure for nonaqueous electrolyte secondary batteries according to the present invention, it is preferable that the polymer particles constituting the intermediate layer are not melted and integrated. The intermediate layer preferably has a structure in which a plurality of polymer particles are bonded to each other directly or through a water-soluble polymer. In addition, in the step of the nonaqueous electrolyte secondary battery structure according to the present invention, the polymer particles may not be bonded to each other or bonded to each other by a water-soluble polymer, and by the electrolyte solution injected when the nonaqueous electrolyte secondary battery is manufactured from the nonaqueous electrolyte secondary battery structure. The polymer particles may be bonded by dissolving or swelling the particle surface.

When the polymer particles having adhesive properties are used as the polymer particles, or when the heat treatment is performed under conditions in which the vicinity of the particle surface is melted in the process of forming the intermediate layer, the intermediate layer has a structure in which the polymer particles directly bond with each other. desirable. In the above structure, it is possible to observe each particle by SEM or the like, but the polymer particles are integrated by directly bonding each other.

In addition, when the polymer particle which does not have adhesiveness is used as a polymer particle, or when heat processing is not performed in the process of forming an intermediate | middle layer, it is preferable to have a structure which a polymer particle contacts each other and is joined by a water-soluble polymer. Do. The said structure is formed by manufacturing an intermediate | middle layer using the liquid containing a polymer particle, a water-soluble polymer, etc. In this structure, it is possible to observe each particle by SEM etc., and a water-soluble polymer exists between each particle.

An intermediate | middle layer can be formed by either of the following (1)-(4), for example.

(1) The intermediate | middle layer is formed by apply | coating the aqueous latex which concerns on this invention to at least 1 sort (s) chosen from an anode, a separator, and a cathode, and drying an aqueous latex.

(2) The intermediate layer is formed by dipping at least one selected from the positive electrode, the separator, and the negative electrode in the aqueous latex according to the present invention, taking it out of the aqueous latex, and drying the aqueous latex.

(3) The aqueous latex according to the present invention is applied to the substrate, the aqueous latex is dried, and then the formed coating film is peeled from the substrate to form an intermediate layer.

(4) The intermediate layer is formed by immersing the substrate in the aqueous latex according to the present invention, taking the substrate out of the aqueous latex, drying the aqueous latex, and then peeling the formed coating film from the substrate.

And when apply | coating the aqueous latex which concerns on this invention to a positive electrode, a separator, a negative electrode, and a base material, what is necessary is just to apply | coat to at least 1 side (namely, one side or both sides).

There is no restriction | limiting in particular as a method at the time of coating | coating, Bar coater; Die coater; Comma coater; Gravure coater, such as direct gravure method, reverse gravure method, kiss reverse gravure method, offset gravure method; Reverse roll coater; Micro gravure coater Air knife coater; The method of apply | coating on a base material using a dip coater etc. is mentioned. Although it is preferable that the intermediate | middle layer formed on the base material is uniform, it may have a shape, such as a hole shape or dotted, for the purpose of sending out the gas produced in the process of charge / discharge.

Also, if desired, heat treatment may be performed after drying. And as another component, when not using a water-soluble polymer, it is preferable to perform heat processing.

And the base material made from polyethylene terephthalate (PET) etc. can be used as a base material at the time of obtaining an intermediate | middle layer by peeling from a base material.

And when using the intermediate | middle layer obtained by peeling from a base material, an intermediate | middle layer is arrange | positioned between an anode and a separator, or between a cathode and a separator, after peeling an intermediate | middle layer from a base material.

As the temperature at the time of drying, it is necessary to consider the melting point, the decomposition temperature, and the like of the separator, the electrode, the substrate, the polymer particles, and other components, so that the suitable temperature and time vary depending on the system. It is preferable that it is 190 degreeC, and it is more preferable that it is 50-180 degreeC. It is preferable that time to perform drying is 1 second-15 hours.

In addition, since the melting | fusing point, decomposition temperature, etc. of a separator, an electrode, a base material, a polymer particle, and another component need to consider the temperature at the time of performing heat processing, although suitable temperature and time differ according to the system, 60-220 degreeC It is preferable that it is and it is more preferable that it is 65-215 degreeC. The time for performing the heat treatment is preferably 1 second to 15 hours.

In addition, although there exist a part in which conditions, such as temperature, overlap in drying and heat processing, drying and heat processing do not need to be clearly distinguished and may be performed continuously.

As a manufacturing method of the structure for nonaqueous electrolyte secondary batteries which concerns on this invention, except having the process of providing the intermediate | middle layer manufactured using the aqueous latex which concerns on this invention between at least one of a positive electrode and a separator, and a negative electrode and a separator, The same method can be used. As described above, the method for producing a structure for a nonaqueous electrolyte secondary battery according to the present invention is characterized in that the intermediate layer is formed by any one of the above (1) to (4).

In the case where the intermediate layer is formed on the separator or the electrode, the structure for the nonaqueous electrolyte secondary battery according to the present invention can be manufactured by the same method as the conventional method except that the separator having the intermediate layer or the electrode having the intermediate layer is used. In addition, when formed by peeling an intermediate | middle layer from a base material, the structure for nonaqueous electrolyte secondary batteries which concerns on this invention except the process which arrange | positions an intermediate | middle layer between at least one of a positive electrode and a separator, and between a negative electrode and a separator is needed, It can manufacture by the same method as before.

In the nonaqueous electrolyte secondary battery structure according to the present invention, an intermediate layer is prepared using the aqueous latex according to the present invention. Therefore, the electrolyte injection path can be prepared in the intermediate layer even without performing the porosity process.

In the nonaqueous electrolyte secondary battery structure according to the present invention and the nonaqueous electrolyte secondary battery described later, since the intermediate layer is prepared using the aqueous latex according to the present invention, the adhesive strength of the separator and the intermediate layer, the adhesive strength of the positive electrode and the intermediate layer, and the negative electrode and It is easy to be excellent in the adhesive strength of an intermediate | middle layer. Therefore, the nonaqueous electrolyte secondary battery structure according to the present invention and the nonaqueous electrolyte secondary battery to be described later, even if a large area, the displacement or peeling due to external force is not easily generated between the positive electrode and the separator and / or between the negative electrode and the separator, Moreover, the area shrinkage rate at the time of separator heating is small, and battery performance can be maintained over a long period of time. In addition, it is easy to obtain a desired capacity.

<Separator / Middle Layer Laminate>

The separator / intermediate layer laminate according to the present invention has a separator for a nonaqueous electrolyte secondary battery and an intermediate layer provided on at least one main surface of the separator, and the intermediate layer (A) a structural unit derived from unsaturated dibasic acid and / or unsaturated dibasic acid monoester. The polymer particle containing the copolymer containing the structural unit derived from the structural unit derived from the vinylidene fluoride system monomer, and (B) inorganic particle are included. In the separator / intermediate layer laminate, the separator and the intermediate layer may directly contact each other, and another layer may be interposed between the separator and the intermediate layer.

The separator, intermediate | middle layer, and polymer particle used for the separator / intermediate | middle layer laminated body which concern on this invention are the same as what was demonstrated above.

<Non-aqueous Electrolyte Secondary Battery>

The nonaqueous electrolyte secondary battery according to the present invention is obtained from the structure for nonaqueous electrolyte secondary batteries.

As a battery structure of a nonaqueous electrolyte secondary battery, well-known battery structures, such as a coin type battery, a button type battery, a cylindrical battery, a square battery, are mentioned, for example.

As a member which comprises a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte solution, a cylindrical can, a laminate pouch, etc. are mentioned other than the structure for nonaqueous electrolyte secondary batteries.

The nonaqueous electrolyte is obtained by dissolving an electrolyte in a nonaqueous solvent.

As said non-aqueous solvent, it is an aprotic organic solvent which can transport the cation and anion which comprise an electrolyte, and the thing which does not substantially impair the function of a secondary battery is mentioned. As such a non-aqueous solvent, the organic solvent normally used as a non-aqueous electrolyte of a lithium ion secondary battery is mentioned, For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, esters, an oxolane compound Etc. can be used. Among them, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1, 2-dimethoxyethane, 1, 2-diethoxyethane, methyl propionate, ethyl propionate, succinonitrile, 1, 3- Propanesultone, fluoroethylene carbonate, vinylene carbonate and the like are preferred.

A non-aqueous solvent can be used individually by 1 type, or 2 or more types can be used.

In addition, as an electrolyte, the kind of constituent cation and anion can be transported by the said non-aqueous solvent, and the kind is not specifically limited as long as it does not substantially impair the function of a secondary battery. Here, when the nonaqueous electrolyte secondary battery is a lithium ion secondary battery, examples of the electrolyte that can be used include lithium salts of fluoro complex anions such as LiPF ₆ , LiAsF ₆ , LBF ₄ , LiClO ₄ , LiCl, LiBr, and the like. Inorganic lithium salts, and sulfonic acid lithium salts such as LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , Li (CF ₃ OSO ₂ ) ₂ N, Li (CF ₃ OSO ₂ ) ₃ C, Li (CF ₃ SO ₂ ) _{2 N, Li (CF 3 SO 2} ) and organic lithium salts such as C _3. The electrolyte may be used alone, or two or more thereof may be used.

And although the nonaqueous electrolyte secondary battery which concerns on this invention is obtained from the structure for nonaqueous electrolyte secondary batteries mentioned above, the intermediate | middle layer which a nonaqueous electrolyte secondary battery structure has is swollen by the electrolyte solution injected at the time of manufacturing a battery, and is further positively pressed by heat press And adhesiveness with a negative electrode can be improved.

As temperature at the time of performing a hot press, it is preferable that it is normal temperature-160 degreeC, and it is more preferable that it is 40-120 degreeC. The pressure at the time of performing a hot press becomes like this. Preferably it is 0.01-10 MPa, More preferably, it is 0.1-8 MPa. When performing a hot press, it is preferable that a preheating time is 1 second-1 hour, and it is preferable that a press time is 1 second-1 hour.

The nonaqueous electrolyte secondary battery as described above may form an electrode having excellent adhesion between the anode-interlayer-separator and / or the cathode-interlayer-separator.

Example

Next, although an Example is shown and this invention is demonstrated in more detail, this invention is not limited by these.

[Production of the anode]

Lithium cobalt acid (Cellseed C5-H, product of Nippon Kagaku Co., Ltd.), conduction aid (SuperP, TIMCAL), and PVDF (polyvinylidene fluoride, KF # 1100, product Kureha) were 93: 3: It mixed with N-methyl- 2-pyrrolidone in the mass ratio of 4, and produced the slurry of 69 mass% of solid content concentration. The slurry was coated on aluminum foil using a 115 μm spacer, dried at 120 ° C. for 3 hours, and then pressed to obtain a positive electrode having a bulk density of 3.6 g / cm 3 and a basis weight of 150 g / m ² . Got.

[Production of the negative electrode]

BTR918 (modified natural graphite, BTR products), conductive additives (SuperP, TIMCAL products), SBR (styrene butadiene rubber latex, BM-400, Nippon Zeon products), and CMC (carboxymethylcellulose, cellogen 4H, Daiichi Kogyo Seiya CU) was mixed with water at a mass ratio of 90: 2: 3: 1 to prepare a slurry having a solid content concentration of 53% by mass. This slurry was coated on copper foil using a 90 μm spacer, dried at 120 ° C. for 3 hours, and then pressed to obtain a negative electrode having a bulk density of 1.5 g / cm 3 and a reference amount of 56 g / m ² .

EXAMPLE 1

280 parts by mass of water was added to the autoclave, and after degassing, 0.5 parts by mass of perfluorooctanoic acid (PFOA) ammonium salt and 0.05 parts by mass of ethyl acetate were added, followed by 20 parts by mass of vinylidene fluoride (VDF) and 5 parts by mass of hexa. Fluoropropylene (HFP) was added.

After heating up at 80 degreeC, 0.5 mass part ammonium persulfate (APS) was put and superposed | polymerized, and 75 mass part VDF and 0.5 mass part monomethyl maleate (MMM) were further added. At that time, monomethyl maleate was used in the form of a 5 mass% aqueous solution, and whenever 5 mass parts of VDF was consumed, the said aqueous solution of the quantity equivalent to 0.033 mass part in monomethyl maleate was added. When the internal pressure of the can fell to 1.5 MPa, the polymerization reaction was terminated to obtain a VDF-HFP-MMM copolymer latex.

It was 23.8 mass% when the obtained VDF-HFP-MMM copolymer latex was dried at 80 degreeC for 3 hours, and the resin concentration was measured. Moreover, it was 187 nm when the average particle diameter was calculated | required using ELSZ-2 by Otsuka Denshi. The slurry obtained by salting out the obtained latex with a 0.5 mass% calcium chloride aqueous solution was washed twice with water, and it dried at 80 degreeC for 21 hours, and obtained the powder. The obtained powder was pressed at 200 ° C. and the IR spectrum was measured. As a result, the absorbance ratio (A _{1740 cm −1} / A _{3020 cm −1} ) was 0.21. And the measurement result of an IR spectrum is shown in FIG.

The obtained VDF-HFP-MMM copolymer latex, CMC (Cellogen 4H, Daiichi Kogyo Seiyaku Co., Ltd.), alumina particles (AKP50, 0.2 μm in average particle diameter, Sumitomo Kagaku Co., Ltd.) and water were used for the VDF-HFP-MMM air. Coalescing: Alumina: CMC (mass ratio) = 60: 40: 2, mixed so that the solid content concentration is 20.5 mass%, the amount of wet coating on both sides of the separator (hipore NH616, Asahi Kasei) It coated sequentially with the wire bar at 36 g / m <^2> , and dried each surface at 70 degreeC for 10 minutes. The air permeability of the obtained coated separator (that is, the intermediate layer / separator / intermediate layer laminate) was measured using a Gurley densometer (manufactured by Toyosei Seisakusho Co., Ltd.) and found to be 263 s / 100 ml. And the air permeability of the separator (high pore NH616) before coating was 200 s / 100 ml. The thickness of the coating film was 4.7 μm on one side.

It was 3.2% when the obtained coating separator was cut | judged to the size of 15 cm x 12 cm (vertical x horizontal), heat-processed in 125 degreeC oven for 30 minutes, and the area shrinkage rate was measured. On the other hand, the area shrinkage rate was similarly measured with respect to the separator (high pore NH616) before coating, and it was 6.7%.

The positive electrode and the negative electrode were cut into 2.5 cm x 5.0 cm, the obtained coated separator was cut into 3.0 cm x 6.0 cm, and the positive electrode, the coated separator, and the negative electrode were stacked in the order of the electrolyte solution (ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate ( After infiltrating 100 mg of volume ratio) = 1/2/2 and LiPF ₆ : 1.3 M), vacuum degassing was enclosed in an aluminum pouch using a vacuum sealing agent. Subsequently, after performing heat for 3 minutes at 100 degreeC on this, the heat press was performed at about 4 MPa for 1 minute. In the obtained anode / coating separator / cathode laminate (ie, anode / middle layer / separator / middle layer / cathode laminate), 180 ° peel strength between the anode and the coated separator, and 180 ° peel strength between the coated separator and the cathode Was measured using a tensilon universal testing machine (manufactured by A & D), and the 180 ° peel strength between the positive electrode and the coated separator was 1.08 gf / mm, and the 180 ° between the coated separator and the negative electrode was measured. Peel strength was 0.09 gf / mm.

[Comparative Example 1]

The VDF-HFP copolymer latex was obtained like Example 1 except having changed the addition amount of ammonium persulfate from 0.5 mass part to 0.06 mass part, and the monomethyl maleate was not added. The resin concentration, average particle diameter, and absorbance ratio were measured in the same manner as in Example 1, and as a result, the resin concentration was 24.6 mass%, the average particle diameter was 195 nm, and the absorbance ratio (A _{1740 cm-1} / A _{3020 cm-1} ) was 0.06. And the measurement result of an IR spectrum is shown in FIG.

Using the obtained VDF-HFP copolymer latex, it carried out similarly to Example 1, and obtained the coating separator. The air permeability of the obtained coated separator was measured in the same manner as in Example 1, and the air permeability was 255 s / 100 ml. The thickness of the coating film was 4.7 μm on one side.

It was 3.7% when the area shrinkage rate of the obtained coated separator was measured similarly to Example 1.

As a result of measuring 180 ° peel strength between the positive electrode and the coated separator and 180 ° peel strength between the coated separator and the negative electrode in the same manner as in Example 1, the 180 ° peel strength between the positive electrode and the coated separator was 0.84 gf / mm And the 180 ° peel strength between the coated separator and the cathode was 0.04 gf / mm.

[evaluation]

In Example 1 where latex was obtained using monomethyl maleate, the absorbance ratio (A _{1740 cm −1} / A _{3020 cm −1} ) was 0.10 or more. In contrast, in Comparative Example 1 in which latex was obtained without using monomethyl maleate, the absorbance ratio (A _{1740 cm −1} / A _{3020 cm −1} ) was less than 0.10.

In addition, the area shrinkage rate of the coated separator of Example 1 was much smaller than the area shrinkage rate of the separator before coating.

In addition, in Example 1, compared with Comparative Example 1, the 180 ° peel strength between the positive electrode and the coated separator and the 180 ° peel strength between the coated separator and the negative electrode were all high, in particular, 180 ° between the coated separator and the negative electrode. The improvement of peeling strength was remarkable.

Claims (6)

It has a separator for nonaqueous electrolyte secondary batteries, and the intermediate | middle layer provided in at least one main surface of the said separator,
The said intermediate | middle layer contains the polymer particle containing the copolymer containing the structural unit derived from (A) unsaturated dibasic acid, and / or the structural unit derived from unsaturated dibasic acid monoester, and the vinylidene fluoride-type monomer, and (B) contains inorganic particles,
The polymer particles absorbance of an infrared absorption spectrum at _{1740 cm} ^-1 A 1740 _cm-1 and the ratio of the absorbance A A _{3020 cm-1} in an infrared absorption spectrum at _{^{3020 cm -1 1740 cm-1 /}} A 3020 cm-1 Is not less than 0.10,
When the separator provided with the intermediate layer was cut to a size of 15 cm x 12 cm (length x width), and heat-treated in an oven at 125 ° C. for 30 minutes, the area shrinkage was 3.2% or less. Separator / Middle Layer Laminate. It has a separator for nonaqueous electrolyte secondary batteries, and the intermediate | middle layer provided in at least one main surface of the said separator,
The said intermediate | middle layer contains the polymer particle containing the copolymer containing the structural unit derived from (A) unsaturated dibasic acid, and / or the structural unit derived from unsaturated dibasic acid monoester, and the vinylidene fluoride-type monomer, and (B) contains inorganic particles,
The polymer particles absorbance of an infrared absorption spectrum at _{1740 cm} ^-1 A 1740 _cm-1 and the ratio of the absorbance A A _{3020 cm-1} in an infrared absorption spectrum at _{^{3020 cm -1 1740 cm-1 /}} A 3020 cm-1 Is not less than 0.10,
The mass ratio of the said polymer particle and the said inorganic particle exists in the range of 70: 30-60: 40, The separator / intermediate | middle layer laminated body characterized by the above-mentioned. The separator / intermediate layered laminate according to claim 1 or 2, wherein an average particle diameter of the polymer particles is 50 nm or more and 700 nm or less. The separator / intermediate layered laminate according to claim 1 or 2, wherein the polymer particles are produced by emulsion polymerization. The separator / middle layer laminated body of Claim 1 or 2 is provided, The structure for nonaqueous electrolyte secondary batteries characterized by the above-mentioned. delete

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