Composition for functional layer of electrochemical element, precursor of composition for functional layer of electrochemical element, functional layer for electrochemical element, laminate for electrochemical element, and electrochemical element

Abstract

The purpose of the present invention is to provide a composition for a functional layer of an electrochemical element, said composition being capable of forming a functional layer that has excellent wet adhesiveness and is capable of satisfactorily suppressing deposition of a metal onto an electrode and expansion of an electrochemical element during charging and discharging. This composition for a functional layer of an electrochemical element is characterized by containing a particulate polymer, the particulate polymer containing a structural unit, the structural unit containing a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring being substituted with a hydroxyl group.

Description

Technical Field

[0001] The present invention relates to a composition for an electrochemical device functional layer, a composition precursor for an electrochemical device functional layer, an electrochemical device functional layer, an electrochemical device laminate, and an electrochemical device. Background Art

[0002] Electrochemical elements such as lithium-ion secondary batteries and electric double layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are used in a wide range of applications. Here, for example, lithium-ion secondary batteries generally have battery components such as a positive electrode, a negative electrode, and a separator that separates the positive electrode from the negative electrode to prevent a short circuit between the positive electrode and the negative electrode.

[0003] Here, in electrochemical elements such as lithium ion secondary batteries, components having a porous film layer for improving heat resistance and strength, an adhesive layer for bonding battery components to each other, etc. (hereinafter collectively referred to as "functional layers") are used. Specifically, an electrode formed by further forming a functional layer on an electrode substrate formed by arranging an electrode composite material layer on a current collector, and a separator formed by forming a functional layer on a separator substrate are used as battery components. Moreover, in recent years, with the purpose of higher performance of electrochemical elements such as lithium ion secondary batteries, further improvements in functional layers are being studied.

[0004] For example, Patent Document 1 proposes a scheme in which the internal resistance of a non-aqueous battery such as a lithium secondary battery is reduced by providing a predetermined electrolyte swellable resin layer as a functional layer on a separator substrate. Specifically, Patent Document 1 proposes a separator for a non-aqueous battery, wherein the separator is formed by forming an electrolyte swellable resin layer formed of a polyurethane resin on at least one surface of a substrate layer formed of a fiber assembly, wherein the polyurethane resin is obtained by reacting a predetermined vinyl polymer, a predetermined polyol, and a polyisocyanate.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent document 1: International Publication No. 2012 / 056890. Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, the following problems exist in the electrochemical elements such as lithium secondary batteries having the functional layers obtained by the above-mentioned prior art: it is not possible to fully suppress the deposition of metals such as lithium on the electrodes during charging and discharging, it is not possible to fully suppress the short circuit between the electrodes caused by the deposition of metals, and it is not possible to fully suppress the expansion of the electrochemical elements accompanying charging and discharging. In addition, in the functional layers obtained by the above-mentioned prior art, there is room for further improvement in the adhesion after immersion in the electrolyte (hereinafter also referred to as "wet adhesion").

[0010] Therefore, an object of the present invention is to provide a composition for an electrochemical element functional layer that can form a functional layer having excellent wet adhesiveness and can well suppress metal deposition on an electrode and expansion of an electrochemical element during charge and discharge.

[0011] Another object of the present invention is to provide a precursor of a composition for an electrochemical device functional layer that can suitably obtain the above-mentioned composition for an electrochemical device functional layer.

[0012] Another object of the present invention is to provide a functional layer for an electrochemical element which has excellent wet adhesiveness and can well suppress the deposition of metal on an electrode and the expansion of the electrochemical element during charge and discharge.

[0013] Another object of the present invention is to provide a laminate for an electrochemical device in which the above-mentioned electrochemical device functional layer is laminated on a substrate.

[0014] Furthermore, an object of the present invention is to provide an electrochemical device having the above-mentioned electrochemical device functional layer.

[0015] Solutions for solving problems

[0016] The present inventors have conducted in-depth research for the purpose of solving the above-mentioned problems. Then, the present inventors found that the above-mentioned problems can be solved by using a composition for an electrochemical element functional layer comprising the following granular polymer, wherein the granular polymer comprises the following structural unit, wherein the structural unit comprises a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted by hydroxyl groups (hereinafter, such structural unit is also referred to as "hydroxyl-substituted aromatic ring structural unit"). In addition, it is also found that the composition for an electrochemical element functional layer comprising the granular polymer can be easily obtained by reducing a composition comprising a granular polymer precursor, wherein the granular polymer precursor comprises the following monomer unit, wherein the monomer unit comprises a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted by alkoxy groups (hereinafter, such monomer unit is also referred to as "alkoxy-substituted aromatic ring monomer unit"), thereby completing the present invention.

[0017] That is, the purpose of the present invention is to advantageously solve the above-mentioned problems. The present invention is [1] a composition for a functional layer of an electrochemical element, which comprises a granular polymer, wherein the granular polymer comprises a structural unit, and the structural unit comprises a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted by a hydroxyl group.

[0018] By using such an electrochemical element functional layer composition, it is possible to obtain a functional layer which is excellent in wet adhesiveness and can well suppress the deposition of metal on the electrode and the expansion of the electrochemical element during charge and discharge.

[0019] In addition, whether the particulate polymer contains the specified structural unit or monomer unit can be used 1 Determination by nuclear magnetic resonance (NMR) methods such as H-NMR.

[0020] [2] In the composition for an electrochemical device functional layer according to [1] above, the degree of swelling of the particulate polymer with respect to the electrolyte is preferably 100% or more and 1000% or less.

[0021] If the electrolyte swelling degree of the particulate polymer is at least the above lower limit, metal deposition on the electrode during charge and discharge can be further suppressed. On the other hand, if the electrolyte swelling degree of the particulate polymer is at most the above upper limit, expansion of the obtained electrochemical element can be further suppressed.

[0022] In the present invention, "the degree of swelling of the particulate polymer into the electrolyte" can be measured by the method described in the Examples.

[0023] [3] In the composition for an electrochemical device functional layer according to [1] or [2], the weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer is preferably 1,000 or more and 500,000 or less.

[0024] When the weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer is within the above-specified range, the wet adhesiveness of the obtained functional layer can be further improved, and the expansion of the obtained electrochemical element can be further suppressed.

[0025] In the present invention, "the weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer" can be measured by the method described in Examples.

[0026] [4] In the composition for an electrochemical device functional layer according to any one of [1] to [3] above, the glass transition temperature of the particulate polymer is preferably 0° C. or higher and 90° C. or lower.

[0027] If the glass transition temperature of the particulate polymer is above the lower limit, the polymer particles can be prevented from becoming unstable and partially coarsening during the preparation of the particulate polymer. On the other hand, if the glass transition temperature of the particulate polymer is below the upper limit, the wet adhesiveness of the obtained functional layer can be further improved.

[0028] In the present invention, "the glass transition temperature of the particulate polymer" can be measured by the method described in Examples.

[0029] [5] In the composition for the functional layer of an electrochemical element of any one of [1] to [4] above, the granular polymer preferably contains more than 1% by mass and less than 50% by mass of the structural unit, wherein the structural unit contains a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted by a hydroxyl group.

[0030] If the particulate polymer contains a structural unit at a ratio greater than the above lower limit, the structural unit contains a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group, the wet adhesiveness of the obtained functional layer can be further improved. On the other hand, if the particulate polymer contains a structural unit at a ratio less than the above upper limit, the structural unit contains a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group, the precipitation of metal onto the electrode during charge and discharge can be further suppressed.

[0031] In the present invention, the content ratio (mass %) of each monomer unit and structural unit can be 1 Determined by nuclear magnetic resonance (NMR) methods such as H-NMR.

[0032] [6] In the composition for an electrochemical device functional layer according to any one of [1] to [5] above, the particulate polymer preferably further contains a crosslinkable monomer unit.

[0033] When the particulate polymer further contains a crosslinkable monomer unit, the wet adhesiveness of the obtained functional layer can be further improved, and the deposition of metal on the electrode during charge and discharge can be further suppressed.

[0034] In the present invention, the particulate polymer "contains a monomer unit" means that "the particulate polymer obtained using the monomer contains a repeating unit derived from the monomer."

[0035] [7] The electrochemical element functional layer composition of any one of [1] to [6] above preferably further comprises heat-resistant particles. If the electrochemical element functional layer composition further comprises heat-resistant particles, a functional layer having excellent heat resistance can be formed, and as a result, the heat resistance of the electrochemical element can be improved.

[0036] In addition, the purpose of the present invention is to advantageously solve the above-mentioned problems. [8] The present invention is a composition precursor for a functional layer of an electrochemical element, which comprises a granular polymer precursor, wherein the granular polymer precursor comprises a monomer unit, and the monomer unit comprises a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted by an alkoxy group.

[0037] When such an electrochemical device functional layer composition precursor is used, an electrochemical device functional layer composition containing a particulate polymer including a hydroxyl-containing substituted aromatic ring structural unit can be preferably obtained by converting the alkoxy groups of the particulate polymer precursor into hydroxyl groups.

[0038] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. [9] The present invention is a functional layer for an electrochemical device, which is formed using the composition for an electrochemical device functional layer according to any one of [1] to [7] above.

[0039] Such a functional layer for an electrochemical element has excellent wet adhesiveness and can suppress the deposition of metal on the electrode and the expansion of the electrochemical element during charge and discharge.

[0040] Furthermore, an object of the present invention is to advantageously solve the above-mentioned problems.

[10] The present invention is a laminate for an electrochemical element, which is formed by laminating the functional layer for an electrochemical element according to [9] above on a substrate.

[0041] Such an electrochemical device laminate can suppress the deposition of metal on the electrode during charge and discharge, and can also suppress the expansion of an electrochemical device having the electrochemical device laminate.

[0042] In addition, the present invention aims to advantageously solve the above-mentioned problems.

[11] The present invention is an electrochemical device having the functional layer for an electrochemical device according to [9] above.

[0043] Such an electrochemical element can suppress the deposition of metal on the electrode during charge and discharge, and can also suppress expansion.

[0044] Effects of the Invention

[0045] According to the present invention, a composition for an electrochemical element functional layer can be provided that can form a functional layer having excellent wet adhesion and can well suppress the deposition of metal on an electrode and the expansion of an electrochemical element during charge and discharge. In addition, according to the present invention, a composition precursor for an electrochemical element functional layer can be provided that can suitably obtain the above-mentioned composition for an electrochemical element functional layer.

[0046] Furthermore, according to the present invention, it is possible to provide a functional layer for an electrochemical element which has excellent wet adhesiveness and can satisfactorily suppress the deposition of metal on an electrode and the expansion of an electrochemical element during charge and discharge.

[0047] Furthermore, according to the present invention, there can be provided a laminate for an electrochemical element in which the above-mentioned electrochemical element functional layer is laminated on a substrate.

[0048] Furthermore, according to the present invention, it is possible to provide an electrochemical device having the above-mentioned electrochemical device functional layer. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described in detail.

[0050] Here, the composition for electrochemical element functional layer of the present invention is used when forming the electrochemical element functional layer possessed by the electrochemical element laminate of the present invention. The composition precursor for electrochemical element functional layer of the present invention is used when obtaining the composition for electrochemical element functional layer of the present invention. The electrochemical element laminate of the present invention has a functional layer formed using the composition for electrochemical element functional layer of the present invention. In addition, the electrochemical element of the present invention has the electrochemical element functional layer of the present invention.

[0051] (Composition for electrochemical element functional layer)

[0052] The electrochemical element functional layer composition of the present invention comprises a specified particulate polymer, and can further optionally comprise one or more components selected from a binder, heat-resistant particles, other components, and a dispersion medium. Moreover, by using the electrochemical element functional layer composition of the present invention, an electrochemical element functional layer having excellent wet adhesion and being able to well suppress the precipitation of metals onto electrodes and the expansion of electrochemical elements during charge and discharge can be formed. In addition, the electrochemical element functional layer composition of the present invention is generally a slurry composition in which the above components are dispersed in a dispersion medium such as water.

[0053] <Particle-like polymer>

[0054] The granular polymer contained in the electrochemical element functional layer composition of the present invention is a polymer containing a specified structural unit as a repeating unit as described in detail below, and has a granular shape in the electrochemical element functional layer composition. In addition, the granular polymer can be granular or in any other shape after the components are bonded to each other via a functional layer formed using the electrochemical element functional layer composition. Furthermore, the granular polymer can be a crystalline polymer, a non-crystalline polymer, or a mixture thereof.

[0055] Furthermore, the particulate polymer may be a block polymer or a random polymer, and is preferably a random polymer.

[0056] <<Composition>>

[0057] The particulate polymer contains a hydroxyl-containing substituted aromatic ring structural unit as a repeating unit, and may further contain other monomer units as desired.

[0058] [Hydroxy-substituted aromatic ring structural unit]

[0059] As described above, the hydroxyl-substituted aromatic ring structural unit used in the present invention is a structural unit containing a group of an aromatic ring in which one or more hydrogen atoms are substituted by a hydroxyl group. It is speculated that in an electrochemical element having a functional layer formed using the electrochemical element functional layer composition of the present invention, the hydroxyl group of the hydroxyl-substituted aromatic ring structural unit contained in the granular polymer captures metal ions (such as cobalt ions, nickel ions, manganese ions, etc.) dissolved from the positive electrode active material, thereby suppressing the precipitation of metals onto the electrode during charge and discharge. In addition, the method for introducing the hydroxyl-substituted aromatic ring structural unit into the granular polymer is not particularly limited, and examples thereof include the following methods (1) or (2).

[0060] (1) A method for preparing a particulate polymer from a monomer composition comprising a hydroxyl-substituted aromatic ring monomer (a monomer comprising a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group), wherein the hydroxyl-substituted aromatic ring monomer has one or more ethylenically unsaturated bonds and one or more aromatic rings, wherein one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group;

[0061] (2) A method for preparing a granular polymer precursor comprising the following monomer units (alkoxy-substituted aromatic ring monomer units), and converting the alkoxy groups of the alkoxy-substituted aromatic ring monomer units of the granular polymer precursor into hydroxyl groups, wherein the above-mentioned monomer units contain a group having one or more aromatic rings, and one or more hydrogen atoms of the above-mentioned aromatic rings are substituted by alkoxy groups.

[0062] Among these, method (2) is preferred.

[0063] Here, the hydroxyl-substituted aromatic ring-containing monomer that can form the hydroxyl-substituted aromatic ring structural unit in the above (1) is not particularly limited, and examples thereof include monomers having one or more ethylenically unsaturated bonds and one or more aromatic rings, wherein one or more hydrogen atoms of the aromatic rings are substituted with hydroxyl groups. Specifically, examples thereof include monomers having one ethylenically unsaturated bond and one or more aromatic rings wherein one or more hydrogen atoms are substituted with hydroxyl groups.

[0064] The aromatic ring substituted with a hydroxyl group is not particularly limited, and examples thereof include aromatic rings having 6 to 18 carbon atoms, such as a benzene ring, a naphthalene ring, an anthracene ring, etc. A benzene ring is particularly preferred.

[0065] The monomer having one ethylenically unsaturated bond and one or more hydrogen atoms substituted with a hydroxyl group is not particularly limited, and examples thereof include o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2,3-dihydroxystyrene, 2,4-dihydroxystyrene, 2,5-dihydroxystyrene, 2,6-dihydroxystyrene, 3,4-dihydroxystyrene (4-vinylcatechol), 2,3,4-trihydroxystyrene, 2,4,6-trihydroxystyrene, 3,4,5-trihydroxystyrene, 2,3,4, 5-tetrahydroxystyrene, pentahydroxystyrene and other hydroxystyrenes; 1-vinyl-2-naphthol, 1-vinyl-2,3-dihydroxynaphthalene, 1-vinyl-2,3,4-trihydroxynaphthalene, 1-vinyl-2,3,5-trihydroxynaphthalene, 1-vinyl-3,4,5-trihydroxynaphthalene, 1-vinyl-2,3,4,5-tetrahydroxynaphthalene, 1-vinyl-2,3,4,5,6-pentahydroxynaphthalene, 1-vinyl-2,3,4,5,6,7-hexahydroxynaphthalene, 1-vinyl-2,3,4,5,6,7,8-heptahydroxynaphthalene Hydroxyvinylnaphthalenes such as hydroxynaphthalene; and 1-vinyl-2-hydroxyanthracene, 1-vinyl-2,3-dihydroxyanthracene, 1-vinyl-3,4-dihydroxyanthracene, 1-vinyl-4,10-dihydroxyanthracene, 1-vinyl-5,10-dihydroxyanthracene, 1-vinyl-6,7-dihydroxyanthracene, 1-vinyl-2,3,4-trihydroxyanthracene, 1-vinyl-3,4,10-trihydroxyanthracene, 1-vinyl-4,5,10-trihydroxyanthracene, 1-vinyl-5,6,7-trihydroxyanthracene, 1-vinyl-7,8, Hydroxyvinyl anthracenes such as 9-trihydroxyanthracene, 1-vinyl-2,3,4,10-tetrahydroxyanthracene, 1-vinyl-5,6,7,8-tetrahydroxyanthracene, 1-vinyl-2,3,4,5,10-pentahydroxyanthracene, 1-vinyl-2,3,4,5,6,10-hexahydroxyanthracene, 1-vinyl-2,3,4,5,6,7,10-heptahydroxyanthracene, 1-vinyl-2,3,4,5,6,7,8,10-octahydroxyanthracene, and 1-vinyl-2,3,4,5,6,7,8,9,10-nonahydroxyanthracene. These hydroxyl-containing substituted aromatic ring monomers may be used alone or in combination of two or more at any ratio.

[0066] Among them, from the viewpoint of further improving the wet adhesion of the obtained functional layer and further suppressing the precipitation of metal onto the electrode and the expansion of the electrochemical element during charge and discharge, as a hydroxyl-substituted aromatic ring monomer capable of forming a hydroxyl-substituted aromatic ring structural unit, a monomer having an ethylenically unsaturated bond and an aromatic ring in which one or more hydrogen atoms are substituted by hydroxyl groups is preferred, and a monomer having an ethylenically unsaturated bond and an aromatic ring in which two hydrogen atoms are substituted by hydroxyl groups is more preferred. From the viewpoint that the distance between the two hydroxyl groups is an appropriate distance and it is easier to capture metal ions, a monomer having an ethylenically unsaturated bond and an aromatic ring in which a hydrogen atom bonded to two adjacent carbon atoms is substituted by hydroxyl groups is further preferred, and 3,4-dihydroxystyrene (4-vinylcatechol) is particularly preferred.

[0067] In addition, in the above (2), the alkoxy-substituted aromatic ring-containing monomer (a monomer containing a group having one or more aromatic rings, wherein one or more hydrogen atoms of the aromatic rings are substituted by alkoxy groups) capable of forming the alkoxy-substituted aromatic ring-containing monomer unit in the granular polymer precursor is not particularly limited as long as the alkoxy group of the alkoxy-substituted aromatic ring-containing monomer unit in the granular polymer precursor can be converted into a hydroxyl group to obtain a granular polymer, and examples thereof include monomers having one or more ethylenically unsaturated bonds and one or more aromatic rings, wherein one or more hydrogen atoms of the aromatic rings are substituted by alkoxy groups. Specifically, examples thereof include monomers having one ethylenically unsaturated bond and one or more hydrogen atoms of the aromatic rings substituted by alkoxy groups.

[0068] The aromatic ring substituted with an alkoxy group is not particularly limited, and examples thereof include aromatic rings having 6 to 18 carbon atoms, such as a benzene ring, a naphthalene ring, an anthracene ring, etc. A benzene ring is particularly preferred.

[0069] The monomer having one ethylenically unsaturated bond and one or more hydrogen atoms substituted with an alkoxy group is not particularly limited, and examples thereof include o-alkoxystyrene, m-alkoxystyrene, p-alkoxystyrene, 2,3-dialkoxystyrene, 2,4-dialkoxystyrene, 2,5-dialkoxystyrene, 2,6-dialkoxystyrene, 3,4-dialkoxystyrene, 2,3,4-trialkoxystyrene, 2,4,6-trialkoxystyrene, 3,4,5-trialkoxystyrene, 2,3,4,5-tetraalkoxystyrene, Alkoxystyrenes such as 1-vinyl-2-alkoxynaphthalene, 1-vinyl-2,3-dialkoxynaphthalene, 1-vinyl-2,3,4-trialkoxynaphthalene, 1-vinyl-2,3,5-trialkoxynaphthalene, 1-vinyl-3,4,5-trialkoxynaphthalene, 1-vinyl-2,3,4,5-tetraalkoxynaphthalene, 1-vinyl-2,3,4,5,6-pentaalkoxynaphthalene, 1-vinyl-2,3,4,5,6,7-hexaalkoxynaphthalene, 1-vinyl-2,3,4,5,6,7,8-heptaalkoxynaphthalene Alkoxyvinylnaphthalenes; and 1-vinyl-2-alkoxyanthracene, 1-vinyl-2,3-dialkoxyanthracene, 1-vinyl-3,4-dialkoxyanthracene, 1-vinyl-4,10-dialkoxyanthracene, 1-vinyl-5,10-dialkoxyanthracene, 1-vinyl-6,7-dialkoxyanthracene, 1-vinyl-2,3,4-trialkoxyanthracene, 1-vinyl-3,4,10-trialkoxyanthracene, 1-vinyl-4,5,10-trialkoxyanthracene, 1-vinyl-5,6,7-trialkoxyanthracene, 1-vinyl-7,8,9 Alkoxyvinyl anthracenes such as 1-vinyl-2,3,4,10-trialkoxyanthracene, 1-vinyl-2,3,4,10-tetraalkoxyanthracene, 1-vinyl-5,6,7,8-tetraalkoxyanthracene, 1-vinyl-2,3,4,5,10-pentaalkoxyanthracene, 1-vinyl-2,3,4,5,6,10-hexaalkoxyanthracene, 1-vinyl-2,3,4,5,6,7,10-heptaalkoxyanthracene, 1-vinyl-2,3,4,5,6,7,8,10-octaalkoxyanthracene, and 1-vinyl-2,3,4,5,6,7,8,9,10-nonaalkoxyanthracene. These alkoxy-substituted aromatic ring-containing monomers may be used alone or in combination of two or more at any ratio.

[0070] Here, the alkoxy group is not particularly limited as long as it can be converted into a hydroxyl group, and for example, an alkoxy group having 1 or more and 6 or less carbon atoms can be used. Among them, from the viewpoint of easy conversion into a hydroxyl group, the alkoxy group is preferably a methoxy group. In the case where the alkoxy-substituted aromatic ring-containing monomer has two or more alkoxy groups, the multiple alkoxy groups may be the same or different, preferably all the same, and more preferably all methoxy groups.

[0071] Among them, as the alkoxy-substituted aromatic ring monomer, a monomer having one each of an ethylenically unsaturated bond and an aromatic ring in which one or more hydrogen atoms are substituted with an alkoxy group is preferred, a monomer having one each of an ethylenically unsaturated bond and an aromatic ring in which two hydrogen atoms are substituted with an alkoxy group is more preferred, and from the viewpoint that the distance between the two hydroxyl groups is an appropriate distance and it is easier to capture metal ions, a monomer having one each of an ethylenically unsaturated bond and an aromatic ring in which hydrogen atoms bonded to two adjacent carbon atoms are substituted with an alkoxy group is further preferred, 3,4-dialkoxystyrene is further preferred, and 3,4-dimethoxystyrene is particularly preferred.

[0072] Here, the treatment for converting the alkoxy groups in the particulate polymer precursor to hydroxy groups (hereinafter also simply referred to as "hydroxyl substitution treatment") is not particularly limited and can be performed, for example, by reacting the alkoxy groups with a Lewis acid in the presence of a solvent.

[0073] As the Lewis acid, boron tribromide, boron trichloride, aluminum tribromide, etc. can be used. These Lewis acids can be used alone or in combination of two or more. The amount of the Lewis acid used is not particularly limited, and can be about 1 to 5 molar equivalents relative to 1 mole of the alkoxy group.

[0074] The solvent is not particularly limited, and halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride, and hydrocarbons such as benzene and toluene can be used. These solvents can be used alone or in combination of two or more.

[0075] The reaction temperature is not particularly limited as long as the alkoxy groups are sufficiently converted to hydroxy groups, and may be -20°C to 80°C. The reaction time is not particularly limited as long as the alkoxy groups are sufficiently converted to hydroxy groups, and may be, for example, 15 minutes to 24 hours.

[0076] The conversion rate of alkoxy groups in the particulate polymer precursor to hydroxyl groups (hydroxyl group conversion rate) is usually 95 mol% or more, preferably 97 mol% or more, and more preferably 99 mol% or more.

[0077] In this way, the structural unit formed by replacing the alkoxy group of the alkoxy-substituted aromatic ring monomer unit with a hydroxyl group becomes the same structural unit as the above-mentioned hydroxyl-substituted aromatic ring structural unit. Specifically, for example, the structural unit formed by replacing the methoxy group of the 3,4-dimethoxystyrene unit with a hydroxyl group becomes the same structural unit as the 3,4-dihydroxystyrene (4-vinylcatechol) unit.

[0078] Furthermore, as the hydroxyl-containing substituted aromatic ring structural unit of the above-mentioned particulate polymer, a structural unit represented by the following structural formula is particularly preferred.

[0079] [Chemical formula 1]

[0080]

[0081] When the content ratio of all repeating units (structural units and monomeric units) in the granular polymer is set to 100 mass%, the content ratio of the hydroxyl-substituted aromatic ring structural units in the granular polymer is preferably 1 mass% or more, more preferably 2 mass% or more, further preferably 5 mass% or more, preferably 50 mass% or less, more preferably 45 mass% or less, further preferably 40 mass% or less.

[0082] When the content ratio of the hydroxyl-substituted aromatic ring structural unit in the particulate polymer is within the above range, the wet adhesiveness of the obtained functional layer can be further improved, and the precipitation of metal onto the electrode during charge and discharge can be further suppressed.

[0083] [Other monomer units]

[0084] The other monomer units that the particulate polymer can optionally contain are not particularly limited, and examples thereof include aromatic vinyl monomer units, (meth) alkyl acrylate monomer units, glycidyl group-containing monomer units, crosslinking monomer units, carboxylic acid group-containing monomer units, amide group-containing monomer units, cyano group-containing monomer units, etc. From the viewpoint of further improving the wet adhesion of the obtained functional layer and further suppressing the precipitation of metal onto the electrode during charge and discharge, the particulate polymer preferably further contains a crosslinking monomer unit.

[0085] -Aromatic vinyl monomer unit-

[0086] As the aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit, for example, styrene, α-methylstyrene, styrene sulfonic acid, butoxystyrene, vinylnaphthalene, etc. can be mentioned, and styrene is particularly preferred. In addition, these aromatic vinyl monomers can be used alone or in combination of two or more at any ratio.

[0087] In the present invention, the "aromatic vinyl monomer unit" is not included in the above-mentioned "hydroxyl-containing substituted aromatic ring structural unit".

[0088] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100 mass%, the content ratio of the aromatic vinyl monomer unit in the granular polymer is preferably 15 mass% or more, more preferably 35 mass% or more, preferably 60 mass% or less, more preferably 50 mass% or less.

[0089] If the content of the aromatic vinyl monomer units in the particulate polymer is greater than or equal to the above lower limit, the wet adhesiveness of the obtained functional layer can be improved. If the content of the aromatic vinyl monomer units in the particulate polymer is less than or equal to the above upper limit, the flexibility of the obtained functional layer can be improved.

[0090] -(Meth)acrylic acid alkyl ester monomer unit-

[0091] As the (meth) alkyl acrylate monomers capable of forming (meth) alkyl acrylate monomer units, for example, butyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate and tert-butyl acrylate, octyl acrylates such as pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate and alkyl acrylates such as acrylates; and butyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate and tert-butyl methacrylate, octyl methacrylates such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, stearyl methacrylate and alkyl methacrylates such as methacrylates. In particular, n-butyl acrylate is preferred. These (meth) alkyl acrylate monomers may be used alone or in combination of two or more in any ratio.

[0092] In the present invention, "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0093] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100 mass%, the content ratio of the (meth)acrylic acid alkyl ester monomer unit in the granular polymer is preferably 15 mass% or more, more preferably 20 mass% or more, and preferably 80 mass% or less, more preferably 60 mass% or less.

[0094] If the content ratio of the (meth)acrylic acid alkyl ester monomer unit in the particulate polymer is greater than the above lower limit, the polymerization reactivity can be improved. In addition, if the content ratio of the (meth)acrylic acid alkyl ester monomer unit in the particulate polymer is less than the above upper limit, the wet adhesiveness of the obtained functional layer can be improved.

[0095] -Glycidyl-containing monomer units-

[0096] The glycidyl-containing monomer capable of forming the glycidyl-containing monomer unit is not particularly limited, and examples thereof include allyl glycidyl ether, glycidyl (meth)acrylate, epoxy-9-decene, epoxy-5-hexene, and the like. In addition, in the present invention, "(meth)acrylate" refers to acrylate and / or methacrylate. Among them, from the viewpoint of suppressing the precipitation of metal onto the electrode during charge and discharge and further improving the wet adhesion of the obtained functional layer, glycidyl methacrylate is preferably used as the glycidyl-containing monomer. These glycidyl-containing monomers may be used alone or in combination of two or more in any ratio.

[0097] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100% by mass, the content ratio of the glycidyl-containing monomer units in the granular polymer is preferably 2% by mass or more, more preferably 5% by mass or more, preferably 44% by mass or less, and more preferably 40% by mass or less. If the content ratio of the glycidyl-containing monomer units in the granular polymer is above the above lower limit, the wet adhesion of the obtained functional layer can be further improved, and the precipitation of metals onto the electrodes during charge and discharge can be further suppressed. In addition, if the content ratio of the glycidyl-containing monomer units in the granular polymer is below the above upper limit, the instability of the polymer particles and the coarsening of some particles during the preparation of the granular polymer can be suppressed.

[0098] - Cross-linking monomer unit-

[0099] As a crosslinking monomer capable of forming a crosslinking monomer unit, for example, a multifunctional monomer having two or more polymerizable reactive groups on the monomer can be cited. As such a multifunctional monomer, for example, allyl (meth)acrylate monomers such as allyl methacrylate; aromatic divinyl monomers such as divinylbenzene and divinylnaphthalene; di(meth)acrylate alkyl ester monomers such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butanediol diacrylate; tri(meth)acrylate alkyl ester monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, etc.

[0100] Here, as the crosslinkable monomer capable of forming the crosslinkable monomer unit, preferably di(meth)acrylate alkyl ester monomers, conjugated diene monomers and aromatic divinyl monomers, among which divinylbenzene and ethylene glycol dimethacrylate are more preferred, and ethylene glycol dimethacrylate is further preferred. In addition, these crosslinkable monomers may be used alone or in combination of two or more in any ratio.

[0101] When the content ratio of all repeating units (structural units and monomer units) in the particulate polymer is set to 100 mass %, the content ratio of the crosslinkable monomer unit in the particulate polymer is preferably 0.1 mass % or more, more preferably 0.3 mass % or more, preferably 2 mass % or less, more preferably 1 mass % or less. If the content ratio of the crosslinkable monomer unit in the particulate polymer is within the above-specified range, the wet adhesiveness of the obtained functional layer can be further improved.

[0102] -Carboxylic acid group-containing monomer unit

[0103] As carboxylic acid group-containing monomers capable of forming carboxylic acid group-containing monomer units, monocarboxylic acids and their derivatives, dicarboxylic acids and their anhydrides, and their derivatives, etc. can be cited. As monocarboxylic acids, acrylic acid, methacrylic acid, crotonic acid, etc. can be cited. As derivatives of monocarboxylic acids, 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, (3-trans-aryloxyacrylic acid, α-chloro-(3-E-methoxyacrylic acid, (3-diaminoacrylic acid, etc. can be cited. As dicarboxylic acids, maleic acid, fumaric acid, itaconic acid, etc. can be cited. As derivatives of dicarboxylic acids, methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid; maleic acid monoesters such as butyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate can be cited.

[0104] Examples of the anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, and citraconic anhydride. These may be used alone or in combination of two or more. Among these, dicarboxylic acids and their derivatives, and anhydrides thereof are preferred, and itaconic acid is more preferred.

[0105] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100% by mass, the content ratio of the carboxylic acid group-containing monomer unit in the granular polymer is preferably greater than 0% by mass, more preferably 0.5% by mass or more, preferably 30% by mass or less, and more preferably 25% by mass or less. If the content ratio of the carboxylic acid group-containing monomer unit in the granular polymer is within the above-defined range, the stability of the electrochemical element functional layer composition during preparation can be improved.

[0106] -Amide-containing monomer units-

[0107] As the amide group-containing monomer capable of forming the amide group-containing monomer unit, methacrylamide, acrylamide, dimethylacrylamide, diethylacrylamide, diacetoneacrylamide, hydroxyethylacrylamide, hydroxymethylacrylamide, hydroxypropylacrylamide, hydroxybutylacrylamide, etc. can be mentioned. These can be used alone or in combination of two or more in any ratio. Among these, acrylamide is preferred.

[0108] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100 mass%, the content ratio of the amide-containing monomer unit in the granular polymer is preferably greater than 0 mass%, more preferably 0.5 mass% or more, preferably 30 mass% or less, and more preferably 25 mass% or less. If the content ratio of the amide-containing monomer unit in the granular polymer is within the above-defined range, the stability of the electrochemical element functional layer composition during preparation can be improved.

[0109] -Cyanide-containing monomer units-

[0110] Examples of cyano-containing monomers that can form cyano-containing monomer units include α,β-ethylenically unsaturated nitrile monomers. Specifically, the α,β-ethylenically unsaturated nitrile monomers are not particularly limited as long as they are α,β-ethylenically unsaturated compounds having a nitrile group, and examples thereof include acrylonitrile; α-halogenated acrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; α-alkyl acrylonitriles such as methacrylonitrile and α-ethylacrylonitrile, etc. Acrylonitrile is particularly preferred.

[0111] In addition, these cyano group-containing monomers may be used alone or in combination of two or more at any ratio.

[0112] When the content ratio of all repeating units (structural units and monomer units) in the granular polymer is set to 100 mass%, the content ratio of the cyano group-containing monomer unit in the granular polymer is preferably greater than 0 mass%, more preferably 0.5 mass% or more, preferably 30 mass% or less, and more preferably 25 mass% or less. If the content ratio of the cyano group-containing monomer unit in the granular polymer is within the above-defined range, the stability of the electrochemical element functional layer composition during preparation can be improved.

[0113] <<Characteristics>>

[0114] [Electrolyte swelling degree]

[0115] The degree of swelling of the particulate polymer with the electrolyte is preferably 100% or more, more preferably 105% or more, further preferably 150% or more, particularly preferably 200% or more, and preferably 1000% or less, more preferably 800% or less, further preferably 500% or less.

[0116] If the electrolyte swelling degree of the particulate polymer is at least the above lower limit, metal deposition on the electrode during charge and discharge can be further suppressed. On the other hand, if the electrolyte swelling degree of the particulate polymer is at most the above upper limit, expansion of the obtained electrochemical element can be further suppressed.

[0117] The degree of swelling of the particulate polymer with the electrolyte can be adjusted by, for example, changing the composition of the particulate polymer.

[0118] [Weight average molecular weight of tetrahydrofuran soluble component]

[0119] The weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer is preferably 1,000 or more, more preferably 3,000 or more, further preferably 5,000 or more, particularly preferably 30,000 or more, and is preferably 500,000 or less, more preferably 450,000 or less, further preferably 400,000 or less.

[0120] When the weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer is within the above-specified range, the wet adhesiveness of the obtained functional layer can be further improved, and the expansion of the obtained electrochemical element can be further suppressed.

[0121] The weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer can be adjusted by, for example, changing the method or conditions for producing the particulate polymer.

[0122] [Glass transition temperature]

[0123] The glass transition temperature of the particulate polymer is preferably 0°C or higher, more preferably 20°C or higher, further preferably 30°C or higher, particularly preferably 52.4°C or higher, and is preferably 90°C or lower, more preferably 87°C or lower, further preferably 75°C or lower.

[0124] If the glass transition temperature of the granular polymer is above the lower limit, the destabilization of the polymer particles and the coarsening of some particles during the preparation of the granular polymer can be suppressed. On the other hand, if the glass transition temperature of the granular polymer is below the upper limit, the wet adhesiveness of the obtained functional layer can be further improved.

[0125] The glass transition temperature of the particulate polymer can be adjusted by, for example, changing the composition of the particulate polymer.

[0126] [Volume average particle size]

[0127] The volume average particle size of the granular polymer is preferably 1.2 μm or more, more preferably 1.5 μm or more, further preferably 3.5 μm or more, preferably 9.0 μm or less, and more preferably 8.5 μm or less. If the volume average particle size of the granular polymer is above the above lower limit, the granular polymer protrudes relative to the material other than the granular polymer on the thickness direction surface of the functional layer formed using the electrochemical element functional layer composition, and becomes easy to contact with battery components such as electrodes and separators, as a result, the functional layer can exert excellent wet adhesion. On the other hand, if the volume average particle size of the granular polymer is below the above upper limit, the precipitation of metal on the electrode during charge and discharge can be further suppressed.

[0128] The volume average particle size of the particulate polymer can be measured by the method described in Examples. The volume average particle size of the particulate polymer can be adjusted by the type and amount of the metal hydroxide used in preparing the particulate polymer, and the preparation method and conditions of the particulate polymer.

[0129] <<Preparation of granular polymer>>

[0130] In the case of preparing a granular polymer into which a hydroxyl-substituted aromatic ring structural unit is introduced by the method (1) above, the granular polymer can be prepared by polymerizing a monomer composition containing the hydroxyl-substituted aromatic ring monomer in an aqueous solvent such as water. Here, the ratio of each monomer in the monomer composition is usually the same as the ratio of each monomer unit in the granular polymer.

[0131] Furthermore, the polymerization method is not particularly limited, and any method such as suspension polymerization, emulsion polymerization coagulation, and pulverization can be used. Among them, suspension polymerization and emulsion polymerization coagulation are preferred, and suspension polymerization is more preferred. In addition, as the polymerization reaction, any reaction such as free radical polymerization and living free radical polymerization can be used.

[0132] Here, as an example, a method for producing a particulate polymer by a suspension polymerization method will be described.

[0133] -Preparation of granular polymer by suspension polymerization-

[0134] [1] Preparation of monomer composition

[0135] First, monomers constituting the desired particulate polymer and other compounding agents (chain transfer agent, polymerization regulator, polymerization reaction retarder, reactive fluidizer, filler, flame retardant, antioxidant, colorant, etc.) added as needed are mixed to prepare a monomer composition.

[0136] [2] Droplet formation

[0137] Next, the monomer composition is dispersed in water, and a polymerization initiator is added to form droplets of the monomer composition. The method for forming the droplets is not particularly limited, and the droplets can be formed, for example, by shearing and stirring water containing the monomer composition using a disperser such as an emulsifying disperser.

[0138] At this time, the polymerization initiator used includes, for example, di(3,5,5-trimethylhexanoyl)peroxide, tert-butyl peroxy-2-ethylhexanoate, azobisisobutyronitrile, etc. In addition, the polymerization initiator may be added after the monomer composition is dispersed in water and before droplets are formed, or may be added to the monomer composition before being dispersed in water.

[0139] In addition, from the viewpoint of stabilizing the droplets of the formed monomer composition in water, it is preferred to add a dispersion stabilizer to water to form the droplets of the monomer composition. In this case, as the dispersion stabilizer, for example, metal hydroxides such as magnesium hydroxide, sodium dodecylbenzene sulfonate, etc. can be used. Here, the dispersion stabilizer can be added in the state of a colloidal dispersion in which the dispersion stabilizer is dispersed in water.

[0140] [3] Aggregation

[0141] After the droplets of the monomer composition are formed, the water containing the formed droplets is heated to initiate polymerization, thereby forming a particulate polymer in water. At this time, the polymerization reaction temperature is preferably 50° C. or higher and 95° C. or lower. In addition, the polymerization reaction time is preferably 1 hour or higher and 10 hours or lower, more preferably 8 hours or lower, and further preferably 7 hours or lower.

[0142] [4] Washing, filtering, dehydration and drying processes

[0143] After the polymerization is completed, the water containing the particulate polymer is washed, filtered and dried according to a conventional method, thereby obtaining the particulate polymer.

[0144] In addition, when preparing a granular polymer into which a hydroxyl-substituted aromatic ring structural unit is introduced by the method of (2) above, the granular polymer precursor can be prepared by polymerizing a monomer composition containing the above-mentioned alkoxy-substituted aromatic ring monomer in an aqueous solvent such as water. In addition, the preparation of the granular polymer precursor uses a monomer composition containing an alkoxy-substituted aromatic ring monomer, and other than that, the same method as the preparation of the granular polymer can be used.

[0145] In the method (2) above, the treatment for converting the alkoxy groups in the particulate polymer precursor into hydroxy groups is not particularly limited, and can be performed, for example, by reacting the alkoxy groups with a Lewis acid in the presence of a solvent.

[0146] As the Lewis acid, boron tribromide, boron trichloride, aluminum tribromide, etc. can be used. These Lewis acids can be used alone or in combination of two or more. The amount of the Lewis acid used is not particularly limited, and can be about 1 to 5 molar equivalents relative to 1 mole of the alkoxy group.

[0147] The solvent is not particularly limited, and halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride, and hydrocarbons such as benzene and toluene can be used. These solvents can be used alone or in combination of two or more.

[0148] The reaction temperature is not particularly limited as long as the alkoxy groups are sufficiently converted to hydroxy groups, and may be -20°C to 80°C. The reaction time is not particularly limited as long as the alkoxy groups are sufficiently converted to hydroxy groups, and may be, for example, 15 minutes to 24 hours.

[0149] The conversion rate of alkoxy groups in the particulate polymer precursor to hydroxyl groups (hydroxyl group conversion rate) is usually 95 mol% or more, preferably 97 mol% or more, and more preferably 99 mol% or more.

[0150] <Bonding material>

[0151] The electrochemical element functional layer composition of the present invention may further contain a binder as desired. If the functional layer composition further contains a binder, wet adhesiveness can be improved.

[0152] <<Composition>>

[0153] As a binder material, there is no particular limitation as long as it does not belong to the above-mentioned granular polymer. Known polymers used as binders include, for example, conjugated diene polymers, acrylic polymers, polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVOH), etc. The binder material can be used alone or in combination of two or more. Moreover, as a binder material, it is preferred that conjugated diene polymers, acrylic polymers, polyvinylidene fluoride (PVDF) and other polymers that are non-water-soluble and can be dispersed in a dispersion medium such as water, more preferably conjugated diene polymers, acrylic polymers, and further preferably acrylic polymers. In addition, when the functional layer is applied to the positive electrode surface of the electrochemical element, the binder material is preferably a material other than a conjugated diene polymer. In addition, in the present invention, the polymer is "non-water-soluble" means that when 0.5g of the polymer is dissolved in 100g of water at a temperature of 25°C, the insoluble component reaches 90% by mass or more.

[0154] Here, conjugated diene polymer refers to a polymer comprising a conjugated diene monomer unit. Moreover, as a specific example of a conjugated diene polymer, it is not particularly limited, and copolymers, butadiene rubber (BR), acrylic rubber (NBR) (comprising a copolymer of acrylonitrile unit and butadiene unit) and their hydrides etc., comprising aromatic vinyl monomer units and aliphatic conjugated diene monomer units, such as styrene-butadiene copolymer (SBR). In addition, as the conjugated diene monomer unit included in the conjugated diene polymer, the monomer units identical with the monomer units described above in the conjugated diene monomer unit that can be included in the granular polymer can be enumerated.

[0155] In addition, an acrylic polymer refers to a polymer containing an alkyl (meth)acrylate monomer unit.

[0156] These adhesive materials may be used alone or in combination of two or more at any ratio.

[0157] <<Glass Transition Temperature>>

[0158] The glass transition temperature of the adhesive material is preferably -100°C or higher, more preferably -90°C or higher, further preferably -80°C or higher, preferably less than 30°C, more preferably 20°C or lower, further preferably 15°C or lower. If the glass transition temperature of the adhesive material is above the lower limit, the wet adhesiveness can be further improved. On the other hand, if the glass transition temperature of the adhesive material is below the upper limit, the flexibility of the functional layer can be further improved.

[0159] <<Content of bonding material>>

[0160] The content of the binder material in the electrochemical element functional layer composition is preferably 10 parts by mass or more, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less relative to 100 parts by mass of the granular polymer. If the content of the binder material is above the above lower limit, the wet adhesiveness can be further improved. On the other hand, if the content of the binder material is below the above upper limit, the ion conductivity of the functional layer can be suppressed from decreasing, and the cycle characteristics of the obtained electrochemical element can be improved.

[0161] In the case where the electrochemical element functional layer composition includes the heat-resistant particles described later, the content of the binding material in the electrochemical element functional layer composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, further preferably 0.5 parts by mass or more, preferably 20 parts by mass or less, relative to 100 parts by mass of the heat-resistant particles. If the content of the binding material is above the above lower limit, the wet adhesion can be further improved. On the other hand, if the content of the binding material is below the above upper limit, the ion conductivity of the functional layer can be suppressed from decreasing, and the cycle characteristics of the obtained electrochemical element can be improved.

[0162] The binder material is not particularly limited, and can be prepared, for example, by polymerizing a monomer composition containing monomers capable of forming the above-mentioned monomer units in an aqueous solvent such as water. Here, the ratio of each monomer in the monomer composition is usually the same as the ratio of each monomer unit in the binder material.

[0163] The polymerization method of the binder material is not particularly limited, and any method such as suspension polymerization, emulsion polymerization, coagulation, and pulverization can be used. In addition, any reaction such as radical polymerization and living radical polymerization can be used as the polymerization reaction.

[0164] The binder material may be in a granular or non-granular shape, but is preferably in a granular shape from the viewpoint of satisfactorily suppressing the components included in the functional layer from falling off.

[0165] <Heat-resistant particles>

[0166] The electrochemical element functional layer composition of the present invention preferably further comprises heat-resistant particles. If the electrochemical element functional layer composition further comprises heat-resistant particles, the heat resistance of the obtained functional layer can be improved.

[0167] The heat-resistant particles are not particularly limited, and examples include particles composed of inorganic materials (i.e., inorganic particles) and particles composed of organic materials (i.e., organic particles) that are stable and electrochemically stable in the use environment of the electrochemical element. In addition, as heat-resistant particles, inorganic particles and organic particles can be used alone or in combination.

[0168] <<Inorganic particles>>

[0169] Examples of the inorganic particles include alumina, 2 O 3 ), aluminum oxide hydrates (boehmite, AlOOH), gibbsite (Al(OH) 3), silicon oxide, magnesium oxide (Magnesia), magnesium hydroxide, calcium oxide, titanium oxide (Titania), barium titanate (BaTiO 3 ), ZrO, alumina-silicon dioxide composite oxide and other inorganic oxide particles; nitride particles such as aluminum nitride and boron nitride; covalent bond grains such as silicon and diamond; insoluble ion grains such as barium sulfate, calcium fluoride, and barium fluoride; clay particles such as talc and montmorillonite. These particles can be subjected to element replacement, surface treatment, solid solution, etc. as needed. In addition, the inorganic particles can be used alone or in combination of two or more.

[0170] <<Organic particles>>

[0171] Organic particles are particles composed of polymers that do not have adhesive properties, unlike the granular polymers and adhesive materials specified above. Here, as organic particles, various cross-linked polymer particles such as cross-linked polymethyl methacrylate, cross-linked polystyrene, cross-linked polydivinylbenzene, styrene-divinylbenzene copolymer cross-linked products, polystyrene, polyimide, polyamide, polyamide-imide, melamine resin, phenolic resin, benzoguanamine-formaldehyde condensate, heat-resistant polymer particles such as polysulfone, polyacrylonitrile, polyaramide, polyacetal, thermoplastic polyimide, and their modified products and derivatives, and heat-resistant organic particles disclosed in International Publication No. 2019 / 065416, etc. In addition, organic particles can be used alone or in combination of two or more. In addition, as described above, organic particles are composed of polymers that do not have adhesive properties. Specifically, the glass transition temperature of the polymer constituting the organic particles is preferably above 150°C.

[0172] Among the above-mentioned heat-resistant particles, from the viewpoint of further improving the heat resistance, inorganic particles and organic particles composed of a polymer having a glass transition temperature of 150° C. or higher are preferred, inorganic particles are more preferred, and particles composed of aluminum oxide (aluminum oxide particles), particles composed of boehmite (boehmite particles), particles composed of barium sulfate (barium sulfate particles), and particles composed of magnesium hydroxide (magnesium hydroxide particles) are further preferred.

[0173] <<Properties of Heat-Resistant Pellets>>

[0174] The volume average particle size of the heat-resistant particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, further preferably 0.3 μm or more, preferably 5.0 μm or less, more preferably 1.0 μm or less, and further preferably 0.8 μm or less. If the volume average particle size of the heat-resistant particles is 0.1 μm or more, it is possible to suppress the over-packing of the heat-resistant particles in the functional layer, thereby reducing the ion conductivity of the functional layer and improving the cycle characteristics of the obtained electrochemical element. On the other hand, if the volume average particle size of the heat-resistant particles is 1.0 μm or less, even if the functional layer is thinned, the electrochemical element component having the functional layer can give full play to its excellent heat resistance. Therefore, the heat resistance of the electrochemical element component can be fully ensured while increasing the capacity of the electrochemical element.

[0175] <<Mixing ratio of heat-resistant particles and granular polymer>>

[0176] The mixing ratio of the heat-resistant particles and the granular polymer in the electrochemical element functional layer composition is preferably 91.5:8.5 to 54.5:45.5 in terms of mass ratio (heat-resistant particles: granular polymer). If the mixing ratio of the heat-resistant particles and the granular polymer is within the above range in terms of mass ratio, the balance between the heat resistance and the adhesiveness of the functional layer becomes better.

[0177] <Other ingredients>

[0178] The composition for the electrochemical element functional layer may contain any other components in addition to the above components. Other components are not particularly limited as long as they do not affect the electrochemical reaction in the electrochemical element, and examples thereof include known additives such as dispersants, wetting agents, thickeners, suspension protective agents, emulsifiers, defoamers, preservatives, and pH adjusters. These other components may be used alone or in combination of two or more.

[0179] <Method for preparing composition for electrochemical element functional layer>

[0180] The preparation method of the composition for the electrochemical element functional layer is not particularly limited, and can be prepared, for example, by mixing the above-mentioned granular polymer, adhesive material, heat-resistant particles, water as a dispersion medium, and other components. In addition, when the granular polymer and the adhesive material are prepared by polymerizing the monomer composition in an aqueous solvent, the granular polymer and the adhesive material can be directly mixed with other components in the state of an aqueous dispersion. In addition, when the granular polymer and the adhesive material are mixed in the state of an aqueous dispersion, the water in the aqueous dispersion can be used as the dispersion medium.

[0181] Here, the mixing method of the above-mentioned components is not particularly limited. In order to disperse the components efficiently, it is preferred to use a dispersing machine as a mixing device for mixing. Moreover, the dispersing machine is preferably a device that can evenly disperse and mix the above-mentioned components. As the dispersing machine, a ball mill, a sand mill, a pigment dispersing machine, a grinding machine, an ultrasonic dispersing machine, a homogenizer, a planetary mixer, etc. can be cited.

[0182] (Precursor composition for electrochemical element functional layer)

[0183] The electrochemical device functional layer composition precursor of the present invention includes a particulate polymer precursor containing an alkoxy-substituted aromatic ring-containing monomer unit, and may further optionally contain a dispersion medium such as water.

[0184] Moreover, by using the electrochemical element functional layer composition precursor of the present invention, a composition for an electrochemical element functional layer comprising the above-mentioned granular polymer can be obtained. Specifically, the electrochemical element functional layer composition precursor can be directly subjected to the above-mentioned hydroxyl substitution treatment, or the granular polymer precursor can be separated from the electrochemical element functional layer composition precursor and arbitrarily dried to obtain a granular polymer precursor to the above-mentioned hydroxyl substitution treatment, thereby obtaining a composition for an electrochemical element functional layer comprising a granular polymer. Then, by using the electrochemical element functional layer composition comprising the obtained granular polymer, an electrochemical element functional layer can be obtained.

[0185] <Particle-like polymer precursor>

[0186] The granular polymer precursor contained in the electrochemical device functional layer composition precursor of the present invention is a polymer containing an alkoxy-substituted aromatic ring-containing monomer unit as a repeating unit and may further contain other monomer units as desired, and has a granular shape in the electrochemical device functional layer composition precursor.

[0187] The alkoxy-substituted aromatic ring monomers that can form the alkoxy-substituted aromatic ring monomer units in the granular polymer precursor, the types and preferred content ratios of the alkoxy-substituted aromatic ring monomer units in the granular polymer precursor, the types and preferred content ratios of other monomer units in the granular polymer precursor, the preferred properties of the granular polymer precursor, and the preparation method of the granular polymer precursor are the same as those described above with respect to the granular polymer. For example, the preferred content ratio of the alkoxy-substituted aromatic ring monomer units in the granular polymer precursor is the same as the preferred content ratio of the hydroxyl-substituted aromatic ring structural units in the above-mentioned granular polymer. In addition, in the present invention, the "aromatic vinyl monomer unit" is not included in the above-mentioned "alkoxy-substituted aromatic ring monomer unit".

[0188] <Method for preparing a composition precursor for an electrochemical element functional layer>

[0189] The preparation method of the electrochemical element functional layer composition precursor is not particularly limited, and it can be prepared, for example, by mixing the above-mentioned granular polymer precursor with water as a dispersion medium. In addition, when the granular polymer precursor is prepared by polymerizing the monomer composition in an aqueous solvent, the aqueous dispersion of the polymer precursor can be directly used as the electrochemical element functional layer composition precursor.

[0190] The mixing method is not particularly limited, but in order to disperse the particulate polymer precursor efficiently, it is preferably mixed using a dispersing machine as a mixing device. Moreover, the dispersing machine is preferably a device that can uniformly disperse the particulate polymer precursor in the dispersion medium. As the dispersing machine, a ball mill, a sand mill, a pigment dispersing machine, a grinding machine, an ultrasonic dispersing machine, a homogenizer, a planetary mixer, etc. can be cited.

[0191] (Functional layer for electrochemical device and laminate for electrochemical device)

[0192] The functional layer for an electrochemical element of the present invention (hereinafter also referred to as "functional layer") is formed using the electrochemical functional layer composition, for example, by applying the electrochemical functional layer composition to the surface (single or double sides) of an appropriate substrate to form a coating, and then drying the formed coating. That is, the functional layer is formed by the dried product of the electrochemical functional layer composition, and the functional layer contains at least the granular polymer, and optionally further contains at least one selected from a binder, heat-resistant particles, and other components.

[0193] In addition, the components contained in the functional layer are the components contained in the above-mentioned composition for the functional layer, and the preferred existence ratio of these components is the same as the preferred existence ratio of the components in the composition for the electrochemical element functional layer. Moreover, since the functional layer is formed using the above-mentioned composition for the electrochemical element functional layer, it has excellent wet adhesion and can well suppress the precipitation of metal on the electrode during charging and discharging and the expansion of the electrochemical element.

[0194] In addition, a laminate formed by forming a functional layer on one or both sides of a substrate can be used as a laminate for an electrochemical element of the present invention (hereinafter also referred to as a "laminate"), which has excellent wet adhesion and can effectively suppress the deposition of metal on the electrode and the expansion of the electrochemical element during charging and discharging.

[0195] <Heat-resistant granular layer>

[0196] Here, in the case where the composition for the electrochemical element functional layer contains heat-resistant particles, the electrochemical element functional layer is not particularly limited and can have a structure in which a portion of the granular polymer is buried in a heat-resistant particle layer containing heat-resistant particles (in other words, a portion of the granular polymer protrudes from the heat-resistant particle layer).

[0197] <<Thickness of Heat-Resistant Particle Layer>>

[0198] Moreover, the thickness of the heat-resistant particle layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, further preferably 1 μm or more, preferably 6 μm or less, more preferably 5 μm or less, and further preferably 3.5 μm or less. If the thickness of the heat-resistant particle layer is above the above lower limit, the heat resistance of the electrochemical element becomes extremely good. On the other hand, if the thickness of the heat-resistant particle layer is below the above upper limit, the ion diffusivity of the functional layer can be ensured and the cycle characteristics of the obtained electrochemical element can be improved.

[0199] <<Ratio of the number average particle size of the particulate polymer to the thickness of the heat-resistant particle layer>>

[0200] In addition, the ratio of the number average particle size of the granular polymer to the thickness of the above-mentioned heat-resistant particle layer (number average particle size of the granular polymer / thickness of the heat-resistant particle layer) is preferably greater than 1.0, more preferably greater than 1.0, further preferably greater than 1.75, preferably less than 5.0, more preferably less than 4.5, and further preferably less than 4.25.

[0201] If the ratio of the number average particle size of the granular polymer to the thickness of the heat-resistant particle layer is greater than the lower limit, the granular polymer becomes more likely to protrude from the surface of the heat-resistant particles on the surface of the functional layer in the thickness direction, and thus good wet adhesiveness can be further exerted. On the other hand, if the ratio of the number average particle size of the granular polymer to the thickness of the heat-resistant particle layer is less than the upper limit, the number of adhesion points of the granular polymer increases, and thus good wet adhesiveness can be exerted, and at the same time, an optimal space is obtained between the separator and the electrode stacked via the functional layer, and the concentration of metal ions such as lithium ions can be suppressed, thereby further suppressing the precipitation of metals onto the electrode during charge and discharge.

[0202] In the present invention, the "thickness of the heat-resistant particle layer" can be measured by the method described in Examples. In the present invention, the "number average particle size of the particulate polymer" in the functional layer can be measured by the method described in Examples.

[0203] <Base Material>

[0204] Here, there is no restriction on the substrate on which the electrochemical element functional layer composition is applied. For example, a coating film of the electrochemical element functional layer composition can be formed on the surface of a release substrate, the coating film is dried to form a functional layer, and the release substrate is peeled off from the functional layer. Like this, the functional layer peeled off from the release substrate can be used as a self-supporting film to form a part of an electrochemical element. However, from the viewpoint of omitting the process of peeling off the functional layer and improving the manufacturing efficiency of the electrochemical element parts, it is preferred to use a separator substrate or an electrode substrate as a substrate. A laminate formed by forming a functional layer on one or both sides of a separator substrate can be well used as a separator having a functional layer, and a laminate formed by forming a functional layer on one or both sides of an electrode substrate can be well used as an electrode having a functional layer.

[0205] <<Spacer Base Material>>

[0206] As the spacer substrate forming the functional layer, there is no particular limitation, for example, the spacer substrate described in Japanese Patent Publication No. 2012-204303 can be used. Among these, from the aspect of being able to thin the overall film thickness of the spacer, thereby being able to increase the ratio of the electrode active material in the electrochemical element and increase the capacity per unit volume, it is preferably a microporous film formed by a polyolefin-based (polyethylene, polypropylene, polybutylene, polyvinyl chloride) resin. In addition, the spacer substrate can include in a part thereof any layer that can play a desired function except the functional layer.

[0207] <<Electrode Base Material>>

[0208] As the electrode substrate (positive electrode substrate and negative electrode substrate) forming the functional layer, there is no particular limitation, and an electrode substrate having an electrode composite material layer formed on a current collector can be cited. Here, the components in the current collector and the electrode composite material layer (such as electrode active material (positive electrode active material, negative electrode active material) and electrode composite material layer binding material (positive electrode composite material layer binding material, negative electrode composite material layer binding material) etc.), and the method for forming the electrode composite material layer on the current collector can use known ones, for example, those described in Japanese Patent Publication No. 2013-145763 can be used. In addition, the electrode substrate can include any layer having a desired function in part thereof except the functional layer.

[0209] <Method for producing functional layer and laminate>

[0210] The method for manufacturing the electrochemical element functional layer and the electrochemical element laminate of the present invention is not particularly limited, and for example, a method of forming a functional layer on a release sheet and transferring the functional layer to a substrate can be used. However, from the viewpoint of not performing a transfer operation and improving manufacturing efficiency, the laminate is preferably manufactured via the following steps: a step of supplying the electrochemical element functional layer composition to the substrate (supply step); and a step of drying the electrochemical element functional layer composition supplied to the substrate (drying step).

[0211] <<Supply process>>

[0212] In the supply process, the composition for the electrochemical element functional layer of the present invention is supplied to a substrate, and a film of the composition for the electrochemical element functional layer is formed on the substrate. The method for supplying the composition for the electrochemical element functional layer on the substrate is not particularly limited, and the composition for the electrochemical element functional layer can be applied to the surface of the substrate, or the substrate can be immersed in the composition for the electrochemical element functional layer. Moreover, from the aspect of the thickness of the functional layer that is easy to control the manufacture, it is preferred that the composition for the electrochemical element functional layer is applied to the surface of the substrate. As a method for applying the composition for the electrochemical element functional layer to the surface of the substrate, it is not particularly limited, and methods such as a scraper method, a reverse roll coating method, a direct roll coating method, a gravure coating method, a rod coating method, an extrusion method, and a brush coating method can be cited. In addition, in the supply process, a film of the composition for the electrochemical element functional layer can be formed only on one side of the substrate, or a film of the composition for the electrochemical element functional layer can be formed on both sides of the substrate.

[0213] <<Drying process>>

[0214] In the drying process, the film of the electrochemical element functional layer composition formed on the substrate in the supply process is dried to remove the dispersion medium to form a functional layer. There is no particular limitation on the method of drying the film of the electrochemical element functional layer composition, and a known method can be used, for example: drying using warm air, hot air, or low-humidity air; vacuum drying; drying using infrared rays, electron beams, etc. There are no particular limitations on the drying conditions, and the drying temperature is preferably 40°C to 150°C, and the drying time is preferably 1 to 30 minutes.

[0215] When producing the laminate of the present invention, after forming the functional layer by subjecting one surface of the substrate to the supply step and the drying step, the functional layer may be further formed by subjecting the other surface of the substrate to the supply step and the drying step.

[0216] <Thickness of Functional Layer>

[0217] The thickness of the functional layer formed on the substrate (hereinafter also referred to as the "maximum thickness of the functional layer") is preferably greater than 1.0 μm, more preferably greater than 1.5 μm, further preferably greater than 2.0 μm, particularly preferably greater than 2.5 μm, most preferably greater than 5.0 μm, preferably less than 10.0 μm, more preferably less than 9.0 μm, and further preferably less than 8.0 μm.

[0218] If the maximum thickness of the functional layer is greater than the lower limit, the heat resistance of the electrochemical element becomes extremely good. On the other hand, if the maximum thickness of the functional layer is less than the upper limit, the ion diffusivity of the functional layer can be ensured, and the cycle characteristics of the obtained electrochemical element can be improved.

[0219] In the present invention, the "maximum thickness of the functional layer" can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

[0220] (Electrochemical Components)

[0221] The electrochemical element of the present invention is characterized in that it has an electrode and a separator, and at least one of the electrode and the separator, preferably the separator, has the functional layer of the present invention. Since at least one of the electrode and the separator uses the functional layer of the present invention, the electrochemical element of the present invention can suppress the precipitation and expansion of the metal on the electrode during charging and discharging. In addition, in the electrochemical element having a functional layer, the granular polymer contained in the functional layer can maintain a granular shape or be in any other shape.

[0222] Furthermore, the electrochemical device of the present invention is not particularly limited, and examples thereof include lithium ion secondary batteries, electric double layer capacitors, and lithium ion capacitors, and preferably lithium ion secondary batteries.

[0223] Here, the following description will take a lithium ion secondary battery as an example of the electrochemical element of the present invention and explain the case where the functional layer of the present invention is used in a separator of the lithium ion secondary battery, but the electrochemical element of the present invention is not limited thereto.

[0224] <Positive and negative electrodes>

[0225] As the positive electrode and the negative electrode, electrodes composed of known electrode substrates (positive electrode substrate and negative electrode substrate) described in the section "Substrate" can be used.

[0226] <Electrolyte>

[0227] As the electrolyte, an organic electrolyte in which a supporting electrolyte is dissolved in an organic solvent can be generally used. As the supporting electrolyte, for example, a lithium salt can be used in a lithium ion secondary battery. Examples of the lithium salt include LiPF 6 、LiAsF6 , LiBF 4 、LiSbF 6 、LiAlCl 4 、LiClO 4 CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi, (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 Among them, LiPF is preferred because it is easily dissolved in a solvent and exhibits a high degree of dissociation. 6 、LiClO 4 CF 3 SO 3 Li. In addition, the electrolyte may be used alone or in combination of two or more. Generally, there is a tendency that the lithium ion conductivity is higher when a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0228] As the organic solvent used in the electrolyte, there is no particular limitation as long as it is a solvent capable of dissolving the supporting electrolyte, and for example, preferably used in lithium ion secondary batteries are: carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), ethyl methyl carbonate (ethyl methyl carbonate (EMC)), and vinylene carbonate; esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as cyclopentane and dimethyl sulfoxide, etc. In addition, a mixed solution of these solvents may also be used.

[0229] Among them, carbonates are preferred because of their high dielectric constant and wide stable potential region. Usually, there is a tendency that the lower the viscosity of the solvent used, the higher the lithium ion conductivity, so the lithium ion conductivity can be adjusted according to the type of solvent. In addition, the concentration of the electrolyte in the electrolyte can be appropriately adjusted. In addition, known additives can also be added to the electrolyte.

[0230] <Method for producing electrochemical element>

[0231] The method for manufacturing the electrochemical element of the present invention is not particularly limited. For example, a lithium ion secondary battery as an example of the electrochemical element of the present invention can be manufactured by overlapping the positive electrode and the negative electrode across a separator, winding and folding the positive electrode and the negative electrode as needed, and placing the electrolyte in a battery container and sealing the battery container. In addition, the functional layer of the present invention is used in at least one component of the positive electrode, the negative electrode, and the separator. In addition, porous metal mesh, fuses, PTC components and other overcurrent protection components, guide plates, etc. can also be placed in the battery container as needed to prevent the pressure inside the battery from rising and overcharging and discharging. The shape of the battery can be any one of, for example, coin-type, button-type, sheet-type, cylindrical, square, flat, etc.

[0232] Example

[0233] Hereinafter, the present invention will be specifically described based on the examples, but the present invention is not limited to these examples. In addition, in the following description, the "%" and "parts" indicating the amount are based on the mass unless otherwise specified. In addition, in the polymer manufactured by polymerizing a plurality of monomers, the proportion of the monomer unit formed by polymerizing a certain monomer in the above-mentioned polymer is usually consistent with the ratio (feed ratio) of the certain monomer in all the monomers used in the polymerization of the polymer unless otherwise specified.

[0234] Various measurements and evaluations in Examples and Comparative Examples were performed according to the following methods.

[0235] <Glass transition temperature>

[0236] The dried particulate polymer prepared in the examples and comparative examples and the dried binder obtained by drying the aqueous dispersion containing the binder prepared in the examples and comparative examples at a temperature of 25°C for 48 hours were used as the measurement samples. 10 mg of the measurement sample was weighed on an aluminum pan, and an empty aluminum pan was used as a control in a differential thermal analysis measuring apparatus ("EXSTAR DSC6220" manufactured by SII NanoTechnology Inc.) to measure the temperature range of -100°C to 500°C at a heating rate of 10°C / min under the conditions specified in JIS Z8703 to obtain a differential scanning calorimetry (DSC) curve. During the heating process, the intersection of the baseline immediately before the endothermic peak of the DSC curve where the differential signal (DDSC) becomes 0.05 mW / min / mg or more and the tangent line of the DSC curve at the inflection point that first appears after the endothermic peak was determined as the glass transition temperature (°C).

[0237] <Measurement of Weight Average Molecular Weight of Tetrahydrofuran-soluble Component>

[0238] The dried particulate polymer prepared in Examples and Comparative Examples was dispersed in ion exchange water to obtain an aqueous dispersion, which was placed in a polytetrafluoroethylene petri dish and dried at 25° C. for 48 hours to obtain a powdered sample.

[0239] Next, 0.3 g of the powder sample was added to a 635-mesh metal mesh bent into a cage shape, and the powder sample in the cage-shaped metal mesh was immersed in 50 g of tetrahydrofuran and allowed to stand at 25° C. for 24 hours.

[0240] By further adding tetrahydrofuran to the tetrahydrofuran solution after immersion, a polymer solution with a concentration of 0.5% was prepared, and the solution was filtered with a 1.0 μm membrane filter to prepare a sample for gel permeation chromatography (GPC). Then, the weight average molecular weight of the tetrahydrofuran-soluble component of the granular polymer was measured by gel permeation chromatography. In addition, the conditions of the mobile phase and chromatographic column of GPC are as follows.

[0241] Device name: HLC-8220GPC;

[0242] Solvent: tetrahydrofuran;

[0243] Polymer solution concentration: 0.5% (10 mg / 2 ml);

[0244] Column: TSKgel SuperMultiporeHZ-M;

[0245] Calibration Polymer: Calibration Polystyrene.

[0246] <Electrolyte swelling degree>

[0247] The dry granular polymer prepared in the examples and comparative examples was dispersed in ion exchange water to obtain an aqueous dispersion, which was placed in a petri dish made of polytetrafluoroethylene. The aqueous dispersion placed in the petri dish was dried at a temperature of 25°C for 48 hours to obtain a powdered sample. About 0.2 g of the sample was pressed at a temperature of 200°C and a pressure of 5 MPa for 2 minutes to obtain a test piece. The weight of the test piece was measured and set as W0.

[0248] Next, the test piece was immersed in an electrolyte solution (1.0 M LiPF 6 The mixture was placed in a solution (containing a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7 as a solvent, 2% by volume of vinylene carbonate and 2% by mass of fluoroethylene carbonate as additives) for 72 hours.

[0249] Take out the immersed test piece from the electrolyte solution and wipe off the electrolyte on the surface of the test piece. Measure the weight of the immersed test piece and set it as W1. Using the measured W0 and W1, calculate the electrolyte swelling degree (mass %) of the granular polymer according to the formula: S = (W1 / W0) × 100.

[0250] <Volume Average Particle Diameter of Granular Polymer>

[0251] The dry granular polymer prepared in the examples and comparative examples was used as the measurement sample. 0.1 g equivalent of the measurement sample was weighed and placed in a beaker, and 0.1 mL of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fujifilm Corporation, "DRYWEL") was added as a dispersant. 10 to 30 mL of a diluent (manufactured by Beckman Coulter, "ISOTON II") was further added to the above beaker, and dispersed for 3 minutes using a 20 W (Watt) ultrasonic disperser. Then, using a particle size measuring machine (manufactured by Beckman Coulter, "MULTISIZER"), under the conditions of pore size: 20 μm, medium: ISOTON II, and number of particles to be measured: 100,000, the D50 (volume average particle size) of the measurement sample under the volume standard was measured.

[0252] <Volume average particle size of the binder>

[0253] The volume average particle size of the binder prepared in the examples and comparative examples is measured by laser diffraction. Specifically, the prepared aqueous dispersion solution containing the binder (adjusted to a solid content concentration of 0.1% by mass) is used as a sample. Then, in the particle size distribution (volume basis) measured using a laser diffraction particle size distribution measuring device (manufactured by Beckman Coulter, "LS-230"), the particle size D50 at which the cumulative volume calculated from the small particle size side becomes 50% is taken as the volume average particle size.

[0254] <Thickness of Heat-Resistant Particle Layer>

[0255] Using a cross-section polisher, the spacer (laminate) with a functional layer made in the embodiment and the comparative example is cut along the stacking direction. Then, using a field emission scanning electron microscope (FE-SEM), the section is observed from a direction perpendicular to the laminate section obtained, and the thickness of the heat-resistant particle layer is calculated according to the obtained image. In addition, the thickness of the heat-resistant particle layer is the distance in the vertical direction from the surface of the spacer on one side of the heat-resistant particle layer to the heat-resistant particles on the surface of the heat-resistant particle layer.

[0256] <Ratio of the number average particle size of the granular polymer to the thickness of the heat-resistant particle layer>

[0257] Use cross-section polisher, the spacer (laminate) with functional layer is cut off along the stacking direction. Then, use field emission scanning electron microscope (FE-SEM), observe its section from the direction perpendicular to the laminate section, measure the particle diameter of 20 granular polymers according to the obtained image, calculate its average value. The calculated average value is used as the number average particle diameter of the granular polymer in the functional layer. Then, by dividing the number average particle diameter by the thickness of the heat-resistant particle layer, the ratio of the number average particle diameter of the granular polymer to the thickness of the heat-resistant particle layer is obtained.

[0258] <Metal Deposition Inhibition>

[0259] The metal precipitation rate on the electrode during charge and discharge of electrochemical elements such as secondary batteries is measured as the ratio of the lithium precipitation area on the negative electrode by the following method. Specifically, the lithium ion secondary battery produced in the embodiment and the comparative example is repeated for 10 cycles of charge and discharge at a constant current of 1.5C at 10°C, and finally charged to a state of charge (SOC) of 100% (metal precipitation test). Then, the battery is disassembled in the glove box to remove the negative electrode, the area of ​​lithium precipitated on the surface of the negative electrode composite material layer is calculated, and the lithium precipitation area ratio (= (area of ​​precipitated lithium / area of ​​the surface of the negative electrode composite material layer) × 100%) is calculated. Then, it is evaluated according to the following standards. In addition, the lower the value of the lithium precipitation area ratio, the better the metal precipitation on the electrode during charge and discharge is suppressed.

[0260] A: The lithium precipitation area ratio is less than 2%;

[0261] B: The lithium precipitation area ratio is 2% or more and less than 5%;

[0262] C: The lithium deposition area ratio is 5% or more.

[0263] <Adhesion after electrolyte immersion (wet adhesion)>

[0264] The separator with functional layer prepared in the examples and comparative examples was cut into strips of 10 mm×50 mm. Then, the separator was placed along the surface of the negative electrode composite material layer side of the negative electrode prepared in the examples and comparative examples through the functional layer to prepare a laminate for evaluation having the separator with functional layer and the negative electrode.

[0265] The evaluation laminate obtained above was cut into strips of 20 mm × 80 mm, placed in a laminate packaging material, injected with about 300 μl of electrolyte, and sealed at 25° C. for 12 hours. At this time, 1.0 M LiPF 6Solution (containing a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7 as a solvent, and 2 volume % of vinylene carbonate and 2 mass % of fluoroethylene carbonate as additives).

[0266] Then, the evaluation laminate was heat-pressed for 20 minutes at a temperature of 80° C. and a load of 0.5 kN using a flat plate press from above the packaging material to obtain a test piece in which the separator with a functional layer and the negative electrode were bonded together.

[0267] Take out the obtained test piece and wipe off the electrolyte attached to the surface. Then, make the negative electrode side of the test piece face down, and stick a transparent tape (transparent tape specified in JIS Z1522) on the surface of the negative electrode side. In addition, fix the transparent tape on a horizontal test bench in advance. Then, measure the stress when one end of the spacer is pulled vertically upward at a tensile speed of 50 mm / min and peeled off. Carry out this measurement 3 times, calculate the average value of the stress, and use the average value as the peel strength. Based on the obtained peel strength, the adhesion of the spacer to the negative electrode after electrolyte impregnation is evaluated according to the following benchmarks. The results are shown in Table 1. In addition, the larger the peel strength value, the better the adhesion (wet adhesion) of the spacer to the negative electrode after electrolyte impregnation.

[0268] A: Peel strength is 5.0N / m or more;

[0269] B: Peel strength is 3.0 N / m or more and less than 5.0 N / m;

[0270] C: Peel strength is less than 3.0 N / m.

[0271] <Battery Swelling Suppression>

[0272] After the metal precipitation test is carried out as described above, the battery is disassembled in a glove box under an argon atmosphere. A contact thickness gauge is used to measure the thickness of the laminate of the negative electrode, the separator, and the positive electrode. Then, the expansion rate of the battery is calculated by the following formula. In addition, the smaller the value, the better the expansion of the battery accompanying charging and discharging is suppressed.

[0273] Battery expansion = (total thickness of the negative electrode, separator and positive electrode after disassembly / total thickness of the negative electrode, separator and positive electrode before electrolyte injection) × 100%

[0274] A: The battery expansion is less than 120%;

[0275] B: The battery expansion is more than 120% and less than 125%;

[0276] C: The battery expands by 125% or more.

[0277] (Example 1)

[0278] <Preparation of Aqueous Dispersion Containing Binder>

[0279] In a reactor equipped with a stirrer, 70 parts of ion exchange water, 0.15 parts of sodium lauryl sulfate (manufactured by Kao Chemical Co., Ltd., "EMAL (registered trademark) 2F") as an emulsifier, and 0.5 parts of ammonium persulfate as a polymerization initiator were supplied, the gas phase was replaced with nitrogen, and the temperature was raised to 60°C.

[0280] On the other hand, in another container, 50 parts of ion exchange water, 0.5 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 94 parts of n-butyl acrylate, 2 parts of methacrylic acid, 2 parts of acrylonitrile, 1 part of allyl methacrylate as a crosslinking monomer, and 1 part of allyl glycidyl ether as a glycidyl group-containing monomer were mixed to prepare a monomer composition.

[0281] The obtained monomer composition was continuously added to the above-mentioned reactor with a stirrer for polymerization over 4 hours. During the addition, the reaction was carried out at 60°C. After the addition was completed, the reaction was terminated after further stirring at 70°C for 3 hours to obtain an aqueous dispersion containing a granular binder material. The volume average particle size of the obtained binder material was 0.25 μm, and the glass transition temperature was -40°C.

[0282] <Preparation of granular polymer (A)>

[0283] [Preparation of Monomer Composition]

[0284] A monomer composition was prepared by mixing 25 parts of 3,4-dimethoxystyrene as an alkoxy-substituted aromatic ring-containing monomer, 15 parts of glycidyl methacrylate as a glycidyl group-containing monomer, 35 parts of styrene as an aromatic vinyl monomer, 24.7 parts of n-butyl acrylate as an alkyl (meth)acrylate monomer unit, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinking monomer.

[0285] [Preparation of Metal Hydroxide]

[0286] To an aqueous solution of 10.0 parts of magnesium chloride dissolved in 200 parts of ion-exchanged water, an aqueous solution of 7.0 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water was slowly added with stirring to prepare a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide.

[0287] [Suspension polymerization method]

[0288] The granular polymer precursor is prepared by suspension polymerization. Specifically, the above-mentioned monomer composition is added to the colloidal dispersion containing magnesium hydroxide, and after further stirring, 2.0 parts of tert-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, "PERBUTYL O") as a polymerization initiator are added to obtain a mixed solution. The obtained mixed solution is stirred at a rotation speed of 12000 rpm for 1 minute using a pipeline emulsifying disperser (manufactured by Ohira Maiko Co., Ltd., "Cavitron") to form droplets of the monomer composition in the colloidal dispersion containing magnesium hydroxide.

[0289] The colloidal dispersion containing magnesium hydroxide, in which droplets of the monomer composition were formed, was placed in a reactor and the temperature was raised to 90° C. to carry out a polymerization reaction for 5 hours, thereby obtaining an aqueous dispersion containing a particulate polymer precursor.

[0290] Furthermore, while stirring the aqueous dispersion containing the granular polymer precursor, sulfuric acid was added dropwise at room temperature (25°C) to perform acid washing until the pH became 6.5 or less. Next, filtration separation was performed, 500 parts of ion exchange water was added to the obtained solid component, slurry was made again, and water washing treatment (washing, filtration and dehydration) was repeated several times. Next, filtration separation was performed, and the obtained solid component was placed in a container of a dryer and dried at 40°C for 48 hours to obtain a granular polymer precursor in a dry state.

[0291] [Conversion of methoxy groups in particulate polymer precursor to hydroxyl groups (hydroxyl substitution treatment)]

[0292] 100 g of the dry granular polymer precursor obtained in the above step is dissolved in 5000 ml of dichloromethane (135-02446 manufactured by Wako Pure Chemical Industries, Ltd.), and after nitrogen bubbling, 300 ml of a 75.7 g / l boron tribromide solution (202207 manufactured by Aldrich) is added, and stirred at 0°C overnight. 2500 ml of water is added to the solution, and then 5000 ml of a 2M sodium chloride aqueous solution is used for centrifugal separation at 10000 rpm, 15 minutes, and 5°C. Then, 5000 ml of methanol is used for centrifugal separation at 10000 rpm, 15 minutes, and 5°C. Then, the obtained granular polymer is dried under vacuum conditions. In the above manner, a dry granular polymer (A) containing catechol structural units formed by converting two methoxy groups on the benzene ring (aromatic ring) into hydroxyl groups is prepared.

[0293] <Preparation of Slurry Composition (Composition for Electrochemical Element Functional Layer)>

[0294] 0.5 parts of sodium polyacrylate as a dispersant was added to 70 parts of alumina as heat-resistant fine particles (AKP3000 manufactured by Sumitomo Chemical Co., Ltd., volume average particle size: 0.7 μm), ion exchange water was added to give a solid content concentration of 55%, and the mixture was mixed using a ball mill to obtain a pre-mixing slurry.

[0295] Furthermore, 5.0 parts of the above-mentioned binder, 25 parts of the above-mentioned granular polymer (A), 1.5 parts of carboxymethyl cellulose as a thickener, and 0.2 parts of sodium dodecylbenzene sulfonate (manufactured by Kao Chemical Co., Ltd., "NEOPELEX G-15") as an emulsifier were mixed with respect to 70 parts of the heat-resistant fine particles contained in the pre-mixed slurry. The obtained mixed solution was added to the pre-mixed slurry. Furthermore, ion exchange water was added in a manner such that the solid content concentration became 40%, and a slurry composition (composition for electrochemical element functional layer) was obtained.

[0296] <Production of a spacer (laminate) with a functional layer>

[0297] A polyethylene microporous film (thickness: 12 μm) was prepared as a separator substrate. The composition for the electrochemical element functional layer obtained above was applied to one side of the prepared separator substrate by a rod coating method. In addition, the coating was dried at 50°C. Then, the same operation as above was performed on the other side of the separator substrate to prepare a separator (laminate) with a functional layer having a heat-resistant particle layer with a thickness of 1.75 μm on both sides of the separator substrate.

[0298] <Production of positive electrode>

[0299] 100 parts of LiCoO as the positive electrode active material 2 (volume average particle size: 12 μm), 2 parts of acetylene black (made by Electrochemical Industry Co., Ltd., "HS-100") as a conductive material, 2 parts of polyvinylidene fluoride (made by Kureha Co., Ltd., "#7208") as a binder for the positive electrode composite material layer in terms of solid content, and N-methylpyrrolidone as a solvent were mixed to make the total solid content concentration 70%. These were mixed by a planetary mixer to prepare a slurry composition for the positive electrode.

[0300] The above-mentioned positive electrode slurry composition is applied to an aluminum foil with a thickness of 20 μm as a current collector in a manner such that the film thickness after drying is about 150 μm using a notch wheel coater, and dried. The drying is performed by transporting the aluminum foil in an oven at 60°C for 2 minutes at a speed of 0.5 m / min. Then, the positive electrode raw material before pressing is obtained by heat treatment at 120°C for 2 minutes. The positive electrode raw material before pressing is rolled using a roller press to obtain a pressed positive electrode having a positive electrode composite material layer (thickness: 60 μm).

[0301] <Production of negative electrode>

[0302] In a 5MPa pressure-resistant container with a stirrer, 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzene sulfonate as an emulsifier, 150 parts of ion exchange water, and 0.5 parts of potassium persulfate as a polymerization initiator were added, and after sufficient stirring, the temperature was raised to 50°C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was terminated to obtain a mixture containing a binder material (SBR) for the negative electrode composite material layer. A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder material for the negative electrode composite material layer, and after adjusting the pH to 8, the unreacted monomers were removed by heating and reduced pressure distillation. Then, it was cooled to below 30°C to obtain an aqueous dispersion containing the desired binder material for the negative electrode composite material layer.

[0303] 80 parts of artificial graphite (volume average particle size: 15.6 μm) as the negative electrode active material (1) and 16 parts of silicon-based active material SiO as the negative electrode active material (2) were mixed. x (Volume average particle size: 4.9 μm) is mixed with 2.5 parts of a 2% aqueous solution of sodium carboxymethyl cellulose (manufactured by Nippon Paper Industries, Ltd., "MAC350HC") as a viscosity regulator in terms of solid content, and ion exchange water is mixed, and after adjusting the solid content concentration to 68%, it is further mixed at 25°C for 60 minutes. Furthermore, after adjusting the solid content concentration to 62% with ion exchange water, it is further mixed at 25°C for 15 minutes to obtain a mixed solution. To the mixed solution, 1.5 parts of the above-mentioned aqueous dispersion containing the binder for the negative electrode composite material layer and ion exchange water in terms of solid content are added, and the final solid content concentration is adjusted to 52%, and then mixed for 10 minutes to obtain a mixed solution. The mixed solution is degassed under reduced pressure to obtain a negative electrode slurry composition with good fluidity.

[0304] The above-mentioned negative electrode slurry composition is applied to a copper foil with a thickness of 20 μm as a current collector in a manner such that the film thickness after drying is about 150 μm using a notch wheel coater, and dried. The drying is performed by transporting the copper foil in an oven at 60°C for 2 minutes at a speed of 0.5 m / min. Then, the negative electrode raw material before pressing is obtained by heat treatment at 120°C for 2 minutes. The negative electrode raw material before pressing is rolled using a roller press to obtain a pressed negative electrode having a negative electrode composite material layer (thickness: 80 μm).

[0305] <Manufacturing of lithium-ion secondary batteries>

[0306] Prepare an outer package of aluminum packaging material as the outer package of the battery. Cut the above-mentioned positive electrode into a square of 4cm×4cm, and arrange it in a manner that the surface on the aluminum foil (current collector) side is in contact with the outer package of the aluminum packaging material. Next, arrange the above-mentioned separator with a functional layer cut into a square of 4.5cm×4.5cm on the surface of the positive electrode composite material layer of the positive electrode. Next, cut the above-mentioned negative electrode into a square of 4.2cm×4.2cm, and arrange it on the separator in a manner that the surface on the negative electrode composite material layer side is opposite to the functional layer of the separator. Then, fill it with LiPF with a concentration of 1.0M as an electrolyte. 6 A solution (containing a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7 as a solvent, 2% by volume of vinylene carbonate and 2% by mass of fluoroethylene carbonate as additives). Furthermore, in order to seal the opening of the aluminum packaging material, heat sealing at a temperature of 150° C. was performed, and the outer package of the aluminum packaging material was sealed to manufacture a laminated battery cell type secondary battery.

[0307] (Example 2)

[0308] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (B) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0309] <Preparation of granular polymer (B)>

[0310] A granular polymer (B) was prepared by the same operation as in Example 1 except that the amount of 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 5 parts and the amount of styrene as the aromatic vinyl monomer was changed from 35 parts to 55 parts when preparing the granular polymer precursor.

[0311] (Example 3)

[0312] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (C) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0313] <Preparation of granular polymer (C)>

[0314] A granular polymer (C) was prepared by the same operation as in Example 1 except that the amount of 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 2 parts and the amount of styrene as the aromatic vinyl monomer was changed from 35 parts to 58 parts when preparing the granular polymer precursor.

[0315] (Example 4)

[0316] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (D) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0317] <Preparation of granular polymer (D)>

[0318] A granular polymer (D) was prepared by the same operation as in Example 1 except that the amount of 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 40 parts and the amount of styrene as the aromatic vinyl monomer was changed from 35 parts to 20 parts when preparing the granular polymer precursor.

[0319] (Example 5)

[0320] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (E) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0321] <Preparation of granular polymer (E)>

[0322] A granular polymer (E) was prepared by the same operation as in Example 1 except that the amount of 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 45 parts and the amount of styrene as the aromatic vinyl monomer was changed from 35 parts to 15 parts when preparing the granular polymer precursor.

[0323] (Example 6)

[0324] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (F) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0325] <Preparation of granular polymer (F)>

[0326] In preparing the granular polymer precursor, the same operation as in Example 1 was carried out except that the amount of n-butyl acrylate as the (meth)acrylate monomer unit was changed from 24.7 parts to 23 parts, and the amount of ethylene glycol dimethacrylate as the crosslinking monomer was changed from 0.3 parts to 2 parts, to prepare a granular polymer (F).

[0327] (Example 7)

[0328] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (G) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0329] <Preparation of granular polymer (G)>

[0330] In preparing the granular polymer precursor, the same operation as in Example 1 was carried out except that the amount of n-butyl acrylate as the (meth)acrylate alkyl ester monomer unit was changed from 24.7 parts to 24.3 parts and the amount of ethylene glycol dimethacrylate as the crosslinking monomer was changed from 0.3 parts to 0.7 parts to prepare a granular polymer (G).

[0331] (Example 8)

[0332] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (H) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0333] <Preparation of granular polymer (H)>

[0334] When preparing a granular polymer precursor, the same operations as in Example 1 were carried out except that the 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 5 parts, the styrene as the aromatic vinyl monomer was changed from 35 parts to 0 parts, the n-butyl acrylate as the (meth)acrylate alkyl ester monomer unit was changed from 24.7 parts to 79.9 parts, and the ethylene glycol dimethacrylate as the crosslinking monomer was changed from 0.3 parts to 0.1 parts, thereby preparing a granular polymer (H).

[0335] (Example 9)

[0336] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (I) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0337] <Preparation of granular polymer (I)>

[0338] When preparing a granular polymer precursor, the same operations as in Example 1 were carried out except that the 3,4-dimethoxystyrene as the alkoxy-substituted aromatic ring monomer was changed from 25 parts to 33 parts, the styrene as the aromatic vinyl monomer was changed from 35 parts to 0 parts, and the n-butyl acrylate as the (meth)acrylate alkyl ester monomer unit was changed from 24.7 parts to 49.7 parts, to prepare a granular polymer (I).

[0339] (Example 10)

[0340] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (J) prepared in the following manner was used instead of the particulate polymer (A) when preparing the slurry composition.

[0341] <Preparation of granular polymer (J)>

[0342] When preparing the granular polymer precursor, the same operation as in Example 1 was carried out except that the amount of t-butyl peroxy-2-ethylhexanoate as the polymerization initiator was changed from 2 parts to 4 parts and t-dodecyl mercaptan (TDM) as the chain transfer agent was added in an amount of 1 part to prepare a granular polymer (J).

[0343] (Example 11)

[0344] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (K) prepared in the following manner was used instead of the particulate polymer (A) when preparing the slurry composition.

[0345] <Preparation of granular polymer (K)>

[0346] When preparing the granular polymer precursor, the same operation as in Example 1 was carried out except that the amount of t-butyl peroxy-2-ethylhexanoate as the polymerization initiator was changed from 2 parts to 4 parts and 0.5 parts of t-dodecyl mercaptan (TDM) as the chain transfer agent was added to prepare a granular polymer (K).

[0347] (Example 12)

[0348] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (L) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0349] <Preparation of granular polymer (L)>

[0350] A granular polymer (L) was prepared in the same manner as in Example 1 except that the amount of t-butyl peroxy-2-ethylhexanoate as a polymerization initiator was changed from 2 parts to 0.5 parts when preparing the granular polymer precursor.

[0351] (Example 13)

[0352] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (M) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0353] <Preparation of granular polymer (M)>

[0354] A granular polymer (M) was prepared in the same manner as in Example 1 except that the amount of t-butyl peroxy-2-ethylhexanoate as a polymerization initiator was changed from 2 parts to 0.3 parts when preparing the granular polymer precursor.

[0355] (Example 14)

[0356] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (N) prepared in the following manner was used instead of the particulate polymer (A) when preparing the slurry composition.

[0357] <Preparation of granular polymer (N)>

[0358] A particulate polymer (N) was prepared by the same operation as in Example 1 except that the colloidal dispersion (B) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (B) was prepared by slowly adding an aqueous solution prepared by dissolving 9.0 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 12.8 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0359] (Example 15)

[0360] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (O) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0361] <Preparation of granular polymer (O)>

[0362] A particulate polymer (O) was prepared by the same operation as in Example 1 except that the colloidal dispersion (C) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (C) was prepared by slowly adding an aqueous solution prepared by dissolving 8.6 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 12.3 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0363] (Example 16)

[0364] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (P) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0365] <Preparation of granular polymer (P)>

[0366] A particulate polymer (P) was prepared by the same operation as in Example 1 except that the colloidal dispersion (D) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (D) was prepared by slowly adding an aqueous solution prepared by dissolving 7.0 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 10.0 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0367] (Example 17)

[0368] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (Q) prepared in the following manner was used instead of the particulate polymer (A) when preparing the slurry composition.

[0369] <Preparation of granular polymer (Q)>

[0370] A particulate polymer (Q) was prepared by the same operation as in Example 1 except that the colloidal dispersion (E) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (E) was prepared by slowly adding an aqueous solution prepared by dissolving 6.7 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 9.6 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0371] (Example 18)

[0372] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a particulate polymer (R) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0373] <Preparation of granular polymer (R)>

[0374] A particulate polymer (R) was prepared by the same operation as in Example 1 except that the colloidal dispersion (F) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (F), a colloidal dispersion containing magnesium hydroxide, was prepared by slowly adding an aqueous solution prepared by dissolving 5.5 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 7.9 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0375] (Example 19)

[0376] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (S) prepared in the following manner was used instead of the particulate polymer (A) when preparing the slurry composition.

[0377] <Preparation of granular polymer (S)>

[0378] A particulate polymer (S) was prepared by the same operation as in Example 1 except that the colloidal dispersion (G) was used instead of the colloidal dispersion (A) containing magnesium hydroxide as the metal hydroxide when preparing the particulate polymer precursor. The colloidal dispersion (G) was prepared by slowly adding an aqueous solution prepared by dissolving 5.3 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution prepared by dissolving 7.6 parts of magnesium chloride in 200 parts of ion-exchanged water under stirring.

[0379] (Comparative Example 1)

[0380] In Example 1, various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that a particulate polymer (T) prepared as follows was used instead of the particulate polymer (A) when preparing the slurry composition.

[0381] <Preparation of granular polymer (T)>

[0382] When preparing a granular polymer precursor, the same operations as in Example 1 were performed except that the amount of 3,4-dimethoxystyrene as an alkoxy-substituted aromatic ring monomer was changed from 24 parts to 0 parts, the amount of styrene as an aromatic vinyl monomer was changed from 35 parts to 60 parts, and no hydroxyl substitution treatment was performed to prepare a granular polymer (T).

[0383] Table 1

[0384]

[0385] From the results shown in Table 1, it can be seen that if a composition for an electrochemical element functional layer comprising a granular polymer is used, and the granular polymer comprises a structural unit, the structural unit comprises a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted by a hydroxyl group, then the obtained functional layer exhibits excellent wet adhesion and can effectively inhibit the deposition of metal on the electrode during charge and discharge and the expansion of the electrochemical element.

[0386] Industrial Applicability

[0387] According to the present invention, a composition for an electrochemical element functional layer can be provided that can form a functional layer having excellent wet adhesion and can well suppress the deposition of metal on the electrode during charge and discharge and the expansion of the electrochemical element. In addition, according to the present invention, a composition precursor for an electrochemical element functional layer can be provided that can suitably obtain the above-mentioned composition for an electrochemical element functional layer.

[0388] Furthermore, according to the present invention, it is possible to provide a functional layer for an electrochemical element which has excellent wet adhesiveness and can satisfactorily suppress the deposition of metal on an electrode and the expansion of an electrochemical element during charge and discharge.

[0389] Furthermore, according to the present invention, there can be provided a laminate for an electrochemical element in which the above-mentioned electrochemical element functional layer is laminated on a substrate.

[0390] Furthermore, according to the present invention, it is possible to provide an electrochemical device having the above-mentioned electrochemical device functional layer.

Claims

1. A composition for an electrochemical element functional layer, comprising a particulate polymer, The particulate polymer includes a structural unit including a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group.

2. The composition for an electrochemical element functional layer according to claim 1, in, The electrolyte swelling degree of the particulate polymer is 100% or more and 1000% or less.

3. The composition for an electrochemical element functional layer according to claim 1, in, The weight average molecular weight of the tetrahydrofuran-soluble component of the particulate polymer is 1,000 or more and 500,000 or less.

4. The composition for an electrochemical element functional layer according to claim 1, in, The glass transition temperature of the particulate polymer is 0° C. or higher and 90° C. or lower.

5. The composition for an electrochemical element functional layer according to claim 1, in, The particulate polymer includes 1% by mass or more and 50% by mass or less of the structural unit, wherein the structural unit includes a group having an aromatic ring, and one or more hydrogen atoms of the aromatic ring are substituted with a hydroxyl group.

6. The composition for an electrochemical element functional layer according to claim 1, in, The particulate polymer further comprises crosslinkable monomer units.

7. The composition for an electrochemical element functional layer according to claim 1, in, The electrochemical element functional layer composition further includes heat-resistant particles.

8. A composition precursor for an electrochemical device functional layer, comprising a granular polymer precursor, wherein the granular polymer precursor comprises a monomer unit, wherein the monomer unit comprises a group having an aromatic ring, wherein one or more hydrogen atoms of the aromatic ring are substituted with an alkoxy group. 9 . An electrochemical device functional layer formed using the electrochemical device functional layer composition according to claim 1 . 10 . A laminate for an electrochemical device, comprising the functional layer for an electrochemical device according to claim 9 laminated on a substrate. 11 . An electrochemical device comprising the functional layer for an electrochemical device according to claim 9 .

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