Composition for electrochemical element functional layer, laminate for electrochemical element, and electrochemical element

Abstract

The objective of the present invention is to provide a composition for an electrochemical element functional layer that can be used to form a functional layer for an electrochemical element, said functional layer exhibiting excellent room-temperature adhesiveness and capable of reducing the internal resistance of an electrochemical element. A composition for an electrochemical element functional layer according to the present invention contains a particulate polymer A. The particulate polymer A has a volume average particle diameter between 0.75 μm and 17.5 μm inclusive. The elution of the particulate polymer A into tetrahydrofuran is between 0.05 mass% and 60 mass% inclusive, and the particulate polymer A has an elastic storage modulus of 35 MPa or less at 25 °C.

Description

Composition for electrochemical device functional layer, laminate for electrochemical device, and electrochemical device

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

[0002] Electrochemical devices 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 therefore used in a wide range of applications. Electrochemical devices generally include components such as a positive electrode, a negative electrode, and a separator that separates the positive electrode from the negative electrode to prevent short-circuiting between the positive electrode and the negative electrode.

[0003] Here, in electrochemical elements such as lithium ion secondary batteries, components including a porous membrane layer for improving heat resistance and strength, an adhesive layer for bonding battery components together, etc. (Hereinafter, these will be collectively referred to as "functional layers for electrochemical elements" and may be abbreviated as "functional layers.") Specifically, an electrode formed by forming a functional layer on an electrode base material formed by providing an electrode mixture layer on a current collector, or a separator formed by forming a functional layer on a separator base material are used as battery components.

[0004] In recent years, further improvements have been investigated in compositions for electrochemical element functional layers (hereinafter sometimes simply referred to as "compositions for functional layers") used to form functional layers, with the aim of further improving the performance of electrochemical elements such as lithium ion secondary batteries (see Patent Documents 1 to 3).

[0005] JP 2023-523279 A JP 2023-515152 A JP 2016-183209 A

[0006] From the viewpoint of improving the productivity of electrochemical devices, it is preferable that the functional layer exhibits high adhesive strength at room temperature (i.e., has excellent room-temperature adhesiveness).Furthermore, from the viewpoint of improving the electrochemical properties, it is preferable that the electrochemical device including the functional layer has low internal resistance.

[0007] However, the conventional functional layer compositions described above have room for improvement in terms of achieving both good room temperature adhesiveness of the functional layer and a reduced internal resistance of the electrochemical element.

[0008] Therefore, an object of the present invention is to provide a composition for an electrochemical device functional layer that can form a functional layer for an electrochemical device that has excellent room temperature adhesion and can reduce the internal resistance of the electrochemical device. Another object of the present invention is to provide a laminate for an electrochemical device that can reduce the internal resistance of the electrochemical device. Another object of the present invention is to provide an electrochemical device with low internal resistance.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and have newly discovered that the above-mentioned problems can be solved by a composition for a functional layer containing a particulate polymer that satisfies predetermined conditions for volume average particle diameter, amount of elution into tetrahydrofuran when formed into a film, and storage modulus at 25°C, and have thus completed the present invention.

[0010] That is, the present invention aims to advantageously solve the above-mentioned problems, and provides the following compositions for electrochemical device functional layers (1) to (11), the following laminate for electrochemical devices (12), and the following electrochemical device (13).

[0011] [1] A composition for an electrochemical device functional layer, comprising a particulate polymer A, wherein the particulate polymer A has a volume average particle diameter of 0.75 μm to 17.5 μm, an amount of elution of the particulate polymer A into tetrahydrofuran of 0.05% by mass to 60% by mass, and a storage modulus at 25°C of 35 MPa or less. Thus, a functional layer composition containing a particulate polymer A having a volume average particle diameter and an amount of elution into tetrahydrofuran (hereinafter sometimes abbreviated as "THF elution amount") within the above-described ranges and a storage modulus at 25°C of not more than the above-described value can satisfactorily produce a functional layer with excellent room-temperature adhesion. Furthermore, the functional layer can reduce the internal resistance of an electrochemical device. In the present invention, the term "volume average particle diameter" refers to the particle diameter (D50) at which the cumulative volume calculated from the smallest diameter side in a particle size distribution (volume-based) measured by a laser diffraction method becomes 50%. This can be measured using the method described in the Examples of this specification. In the present invention, the "THF elution amount" and "storage modulus at 25° C." of the particulate polymer A can be measured by the methods described in the examples of the present specification.

[0012] [2] The composition for an electrochemical device functional layer according to [1] above, wherein the number-average molecular weight of the tetrahydrofuran elutable component of the particulate polymer A is 500 or more and 500,000 or less. When the number-average molecular weight of the tetrahydrofuran (THF) elutable component of the particulate polymer A is within the above-mentioned range, the room temperature adhesiveness of the functional layer can be further improved and the internal resistance of the electrochemical device can be further reduced. In the present invention, the "number-average molecular weight of the THF elutable component" can be measured using the method described in the examples of this specification.

[0013] [3] The composition for an electrochemical device functional layer according to [1] or [2] above, wherein the particulate polymer A has a glass transition temperature of −50° C. or higher and 95° C. or lower. When the glass transition temperature of the particulate polymer A is within the above range, the blocking resistance of the functional layer can be improved while the room temperature adhesiveness can be further enhanced. In the present invention, the “glass transition temperature” of the particulate polymer A can be measured using the method described in the examples of this specification.

[0014] [4] The composition for an electrochemical device functional layer according to any one of [1] to [3] above, wherein the particulate polymer A has an electrolyte swelling degree of 100% or more and 500% or less. When the electrolyte swelling degree of the particulate polymer A is within the above-mentioned range, the room temperature adhesiveness of the functional layer can be further improved and the internal resistance of the electrochemical device can be further reduced. In the present invention, the "electrolyte swelling degree" of the particulate polymer A can be measured using the method described in the examples of this specification.

[0015] [5] The composition for an electrochemical device functional layer according to any one of [1] to [4] above, further comprising a dispersion medium containing water and having a pH of 3.0 or more and 12.0 or less. By adjusting the pH of the composition for a functional layer within the above range, the dispersibility of the composition for a functional layer can be improved and the room-temperature adhesion of the functional layer can be further enhanced. In the present invention, the "pH" of the composition for a functional layer refers to the pH measured at 25°C, and can be measured using the method described in the examples of this specification.

[0016] [6] The composition for an electrochemical device functional layer according to any one of [1] to [5] above, further comprising a particulate polymer B different from the particulate polymer A and a dispersant, wherein the mass ratio of the particulate polymer A to the particulate polymer B (particulate polymer A / particulate polymer B) is 1 / 99 or more and 99 / 1 or less. The composition for a functional layer further comprising the particulate polymer B and a dispersant, wherein the mass ratio of the particulate polymer A to the particulate polymer B is within the above-mentioned range, can further enhance the room temperature adhesion of the functional layer and further reduce the internal resistance of the electrochemical device.

[0017] [7] The composition for an electrochemical device functional layer according to any one of [1] to [6] above, wherein the particulate polymer A contains aromatic vinyl monomer units in a proportion of 10% by mass or more. If the proportion of aromatic vinyl monomer units in the particulate polymer A is equal to or greater than the above value, the blocking resistance of the functional layer can be improved while further enhancing room-temperature adhesion. In the present invention, the "monomer unit" of a polymer means "a repeating unit derived from the monomer contained in a polymer obtained using the monomer." The content ratio of the monomer unit in the polymer is: １ It can be measured using a nuclear magnetic resonance (NMR) method such as H-NMR.

[0018] [8] The composition for an electrochemical device functional layer according to any one of [1] to [7] above, wherein the particulate polymer A contains a crosslinkable monomer unit in a proportion of 0.01% by mass or more and 50% by mass or less. When the proportion of the crosslinkable monomer unit in the particulate polymer A is within the above range, the room temperature adhesiveness of the functional layer can be further improved and the internal resistance of the electrochemical device can be further reduced.

[0019] [9] The composition for an electrochemical device functional layer according to any one of [1] to [8] above, wherein the particulate polymer A has a core-shell structure. When the particulate polymer A has a core-shell structure, the blocking resistance of the functional layer can be improved and room temperature adhesion can be further enhanced.

[0020]

[10] The composition for an electrochemical device functional layer according to [9] above, wherein the mass ratio of the core part to the shell part of the core-shell structure (core part / shell part) is 0.1 / 99.9 or more and 99.9 / 0.1 or less. When the particulate polymer A has a core-shell structure in which the mass ratio of the core part to the shell part is within the above range, the blocking resistance of the functional layer can be improved and the room temperature adhesion can be further enhanced.

[0021]

[11] The composition for an electrochemical device functional layer according to any one of [1] to

[10] above, further comprising non-conductive heat-resistant particles. The composition for a functional layer further comprising non-conductive heat-resistant particles can improve the heat resistance of the functional layer.

[0022]

[12] A laminate for electrochemical devices, comprising a substrate and a functional layer for electrochemical devices formed on the substrate, the functional layer for electrochemical devices being formed using the composition for electrochemical device functional layers described in any one of [1] to

[11] above. A laminate for electrochemical devices (hereinafter sometimes simply referred to as "laminate") comprising a functional layer formed using any one of the functional layer compositions described above can reduce the internal resistance of an electrochemical device.

[0023]

[13] An electrochemical device comprising the laminate for an electrochemical device according to

[12] above. The electrochemical device comprising the above-mentioned laminate has reduced internal resistance.

[0024] According to the present invention, it is possible to provide a composition for an electrochemical device functional layer that is capable of forming an electrochemical device functional layer that has excellent room temperature adhesion and can reduce the internal resistance of the electrochemical device. Further, according to the present invention, it is possible to provide a laminate for an electrochemical device that can reduce the internal resistance of the electrochemical device. And according to the present invention, it is possible to provide an electrochemical device with low internal resistance.

[0025] Hereinafter, embodiments of the present invention will be described in detail. Here, the functional layer composition of the present invention can be used as a material for forming a functional layer included in the laminate of the present invention. The laminate of the present invention is characterized by including a functional layer formed using the functional layer composition of the present invention. Furthermore, the electrochemical element of the present invention includes the laminate of the present invention. Note that the functional layer formed using the functional layer composition of the present invention not only exhibits adhesive properties for bonding electrochemical element components together, but may also have a function for improving the heat resistance and strength of electrochemical element components such as separators and electrodes.

[0026] (Composition for electrochemical device functional layer) The composition for functional layer of the present invention contains a particulate polymer A, and optionally further contains a particulate polymer B, a dispersion medium, a dispersant, non-conductive heat-resistant particles, and other components. Here, the composition for functional layer of the present invention is characterized in that the volume average particle size and THF elution amount of the particulate polymer A are each within a predetermined range, and the storage modulus of the particulate polymer A at 25°C is a predetermined value or less. Note that the composition for functional layer of the present invention usually does not contain an electrode active material.

[0027] Since the composition for a functional layer of the present invention contains the particulate polymer A that satisfies the above-mentioned properties, the use of the composition for a functional layer of the present invention allows the functional layer to exhibit excellent room temperature adhesion and reduces the internal resistance of the electrochemical element. The reason why the use of the composition for a functional layer of the present invention provides the above-mentioned effects is not clear, but is presumed to be as follows.

[0028] First, the particulate polymer A contained in the functional layer composition of the present invention has a relatively large volume average particle diameter of 0.75 μm or more and 17.5 μm or less. Therefore, on the thickness direction surface of a functional layer formed using the functional layer composition of the present invention, the particulate polymer A protrudes relative to materials other than the particulate polymer A, making it easier to contact the electrochemical device component, thereby improving the adhesiveness of the functional layer. In addition, since the storage modulus of the particulate polymer A at 25°C is 35 MPa or less and the THF elution amount of the particulate polymer A is 0.05 mass% or more, the particulate polymer A easily deforms at room temperature at the contact surface between the functional layer formed using the functional layer composition of the present invention and the electrochemical device component, thereby exhibiting good room temperature adhesive strength. Furthermore, since the THF elution amount of the particulate polymer A is 60 mass% or less, the amount of elution of the particulate polymer A into the electrolyte is reduced, and an increase in the internal resistance of the electrochemical device due to the eluted particulate polymer A being adsorbed on the surface of the electrode active material or blocking the separator pores can be suppressed. Furthermore, as described above, since the volume average particle diameter of the particulate polymer A is relatively large, the separator pores are less likely to be blocked by the particulate polymer A dissolved in the electrolyte, and an increase in the internal resistance of the electrochemical element can be suppressed. For the reasons described above, it is considered that use of the composition for a functional layer of the present invention can improve the room temperature adhesiveness of the functional layer and reduce the internal resistance of the electrochemical element.

[0029] <Particulate polymer A> The particulate polymer A has the function of imparting excellent adhesiveness to a functional layer formed using a functional layer composition. Here, the "particulate polymer" is a polymer that is dispersible in an aqueous medium such as water, and exists in the form of particles in the aqueous medium. Usually, the particulate polymer A is water-insoluble. In the present invention, the particles being "water-insoluble" means that when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25°C, the insoluble content is 90 mass% or more.

[0030] The composition of the particulate polymer A is not particularly limited as long as it satisfies the above-mentioned conditions of volume average particle size, THF elution amount and storage modulus.Among them, the particulate polymer A preferably contains at least a crosslinkable monomer unit, and more preferably contains an aromatic vinyl monomer unit and a crosslinkable monomer unit.In addition, the particulate polymer A may contain a monomer unit other than the aromatic vinyl monomer unit and the crosslinkable monomer unit (hereinafter referred to as "other monomer unit").

[0031] <<Aromatic vinyl monomer unit>> Examples of aromatic vinyl monomers that can form aromatic vinyl monomer units include styrene, α-methylstyrene, p-t-butylstyrene, butoxystyrene, vinyltoluene, chlorostyrene, and vinylnaphthalene. These may be used alone or in combination of two or more. Among these, styrene is preferred.

[0032] The proportion of aromatic vinyl monomer units in the particulate polymer A is preferably 10% by mass or more, more preferably 11.5% by mass or more, and even more preferably 13% by mass or more, and is preferably 99% by mass or less, more preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, based on 100% by mass of the total monomer units in the particulate polymer A. If the proportion of aromatic vinyl monomer units in the particulate polymer A is equal to or greater than the lower limit, the glass transition temperature of the particulate polymer A is increased, and the blocking resistance of the functional layer can be improved. Furthermore, if the proportion of aromatic vinyl monomer units in the particulate polymer A is equal to or less than the upper limit, the room temperature adhesion of the functional layer can be further improved.

[0033] <<Crosslinkable Monomer Unit>> Examples of crosslinkable monomers that can form crosslinkable monomer units include crosslinkable monomers having a thermally crosslinkable crosslinking group and one olefinic double bond per molecule; and crosslinkable monomers having two or more olefinic double bonds per molecule.

[0034] Examples of the thermally crosslinkable group include an epoxy group, an N-methylolamide group, an oxetanyl group, an oxazoline group, and combinations thereof. Of these, an epoxy group is preferred.

[0035] Examples of crosslinkable monomers having an epoxy group as a thermally crosslinkable crosslinkable group and an olefinic double bond include unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, and o-allylphenyl glycidyl ether; diene or polyene monoepoxides such as butadiene monoepoxide, chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, and 1,2-epoxy-5,9-cyclododecadiene; 3,4 alkenyl epoxides such as 1,2-epoxy-1-butene, 1,2-epoxy-5-hexene, and 1,2-epoxy-9-decene; and glycidyl esters of unsaturated carboxylic acids such as glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl 4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl 4-methyl-3-pentenoate, glycidyl ester of 3-cyclohexenecarboxylic acid, and glycidyl ester of 4-methyl-3-cyclohexenecarboxylic acid.

[0036] Furthermore, examples of crosslinkable monomers having an N-methylolamide group as a thermally crosslinkable crosslinkable group and having an olefinic double bond include (meth)acrylamides having a methylol group, such as N-methylol(meth)acrylamide. In the present invention, "(meth)acryl" means acrylic and / or methacrylic.

[0037] Furthermore, examples of crosslinkable monomers having an oxetanyl group as a thermally crosslinkable crosslinkable group and having an olefinic double bond include 3-((meth)acryloyloxymethyl)oxetane, 3-((meth)acryloyloxymethyl)-2-trifluoromethyloxetane, 3-((meth)acryloyloxymethyl)-2-phenyloxetane, 2-((meth)acryloyloxymethyl)oxetane, and 2-((meth)acryloyloxymethyl)-4-trifluoromethyloxetane.

[0038] Furthermore, examples of crosslinkable monomers having an oxazoline group as a thermally crosslinkable crosslinkable group and having an olefinic double bond include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline.

[0039] Further, examples of crosslinkable monomers having two or more olefinic double bonds per molecule include butadiene, isoprene, allyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipropylene glycol diallyl ether, polyglycol diallyl ether, triethylene glycol divinyl ether, hydroquinone diallyl ether, tetraallyloxyethane, trimethylolpropane diallyl ether, allyl or vinyl ethers of polyfunctional alcohols other than those mentioned above, triallylamine, methylenebisacrylamide, and divinylbenzene. In the present invention, "(meth)acrylate" means acrylate and / or methacrylate.

[0040] The above-mentioned crosslinkable monomers may be used alone or in combination of two or more. Among these, ethylene glycol dimethacrylate and glycidyl methacrylate are preferred.

[0041] The proportion of the crosslinkable monomer units in the particulate polymer A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 15% by mass or less, particularly preferably 12% by mass or less, based on 100% by mass of all monomer units in the particulate polymer A. If the proportion of the crosslinkable monomer units in the particulate polymer A is equal to or greater than the lower limit, the elution of the particulate polymer A into the electrolyte can be suppressed, and the internal resistance of the electrochemical element can be further reduced. Furthermore, if the proportion of the crosslinkable monomer units in the particulate polymer A is equal to or less than the upper limit, the room temperature adhesion of the functional layer can be further improved.

[0042] <<Other Monomer Units>> Examples of the other monomer units include (meth)acrylic acid ester monomer units. The particulate polymer A preferably contains (meth)acrylic acid ester monomer units as the other monomer units.

[0043] Examples of (meth)acrylic acid ester monomers that can form (meth)acrylic acid ester monomer units include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and 2-ethylhexyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and 2-ethylhexyl methacrylate. These may be used alone, or two or more may be used in combination in any ratio. Among these, n-butyl acrylate and 2-ethylhexyl acrylate are preferred as the (meth)acrylic acid ester monomer.

[0044] The proportion of the (meth)acrylic acid ester monomer units in the particulate polymer A is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 29% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on 100% by mass of the total monomer units in the particulate polymer A. If the proportion of the (meth)acrylic acid ester monomer units in the particulate polymer A is equal to or greater than the lower limit, the room temperature adhesiveness of the functional layer can be further improved. Furthermore, if the proportion of the (meth)acrylic acid ester monomer units in the particulate polymer A is equal to or less than the upper limit, the blocking resistance of the functional layer can be improved.

[0045] The particulate polymer A may be a particle formed of one type of polymer (single polymer particle) or a particle formed of two or more types of polymers (composite polymer particle). Composite polymer particles are heterophase structures in which different polymer portions exist inside the particle. Here, the heterophase structure refers to a single particle formed by the physical or chemical bonding of two or more different polymers, and is not a particle having a single phase structure formed from a single polymer such as a block polymer. Specific examples of heterophase structures include a core-shell structure in which spherical particles have a core and a shell covering at least a portion of the outer surface of the core, each formed from a different polymer; and a side-by-side structure in which two or more polymers are juxtaposed. Among these, from the viewpoint of further improving the room temperature adhesiveness while improving the blocking resistance of the functional layer, it is preferable that the particulate polymer A has a core-shell structure.

[0046] <<Core-shell structure>> Here, in the particulate polymer A having a core-shell structure, the shell part may cover the entire outer surface of the core part, or may cover the outer surface of the core part partially. Even if the outer surface of the core part appears to be completely covered by the shell part from the outside, as long as holes communicating between the inside and outside of the shell part are formed, the shell part partially covers the outer surface of the core part. Therefore, for example, a particulate polymer A comprising a shell part having pores communicating from the outer surface of the shell part (i.e., the peripheral surface of the particulate polymer A) to the outer surface of the core part corresponds to a particulate polymer A in which the shell part partially covers the outer surface of the core part.

[0047] The particulate polymer A having a core-shell structure may have any constituent element other than the core part and shell part described above, as long as the intended effect is not significantly impaired. Specifically, for example, the particulate polymer A may have a portion formed of a polymer different from the core part inside the core part. As a specific example, the seed particles used when producing the core part by the seed polymerization method may remain inside the core part. However, from the viewpoint of significantly exhibiting the intended effect, it is preferable that the particulate polymer A has only the core part and the shell part.

[0048] [Core Portion] The monomer unit contained in the polymer of the core portion is not particularly limited, but preferred examples include an aromatic vinyl monomer unit and a crosslinkable monomer unit. The polymer of the core portion may contain only one type of monomer unit or multiple types.

[0049] -Aromatic vinyl monomer unit- Examples of aromatic vinyl monomers that can form the aromatic vinyl monomer unit in the core polymer include those similar to those described above. These may be used alone or in combination. Among these, styrene is preferred.

[0050] The proportion of aromatic vinyl monomer units contained in the core polymer is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 4% by mass or more, and is preferably 99% by mass or less, more preferably 90% by mass or less, even more preferably 75% by mass or less, and particularly preferably 60% by mass or less, based on 100% by mass of all monomer units contained in the core polymer. If the proportion of aromatic vinyl monomer units in the core polymer is equal to or greater than the lower limit, the glass transition temperature of the core polymer is increased, thereby improving the blocking resistance of the functional layer. Furthermore, if the proportion of aromatic vinyl monomer units in the core polymer is equal to or less than the upper limit, the room temperature adhesion of the functional layer can be further improved.

[0051] Crosslinkable Monomer Units Examples of crosslinkable monomers that can form crosslinkable monomer units in the core polymer include those described above. These may be used alone or in combination. Among these, ethylene glycol dimethacrylate and glycidyl methacrylate are preferred.

[0052] The proportion of crosslinkable monomer units contained in the core polymer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less, based on 100% by mass of all monomer units contained in the core polymer. If the proportion of crosslinkable monomer units in the core polymer is equal to or greater than the lower limit, elution of the particulate polymer A into the electrolyte can be suppressed, and the internal resistance of the electrochemical device can be further reduced. Furthermore, if the proportion of crosslinkable monomer units in the core polymer is equal to or less than the upper limit, the room temperature adhesion of the functional layer can be further improved.

[0053] —Other Monomer Units— The monomer units (other monomer units) other than the aromatic vinyl monomer units and the crosslinkable monomer units that the core polymer may contain are not particularly limited, and examples thereof include (meth)acrylic acid ester monomer units.

[0054] Examples of (meth)acrylic acid ester monomers that can form the (meth)acrylic acid ester monomer units in the core polymer include the same as those mentioned above. These may be used alone or in combination. Among these, n-butyl acrylate and 2-ethylhexyl acrylate are preferred.

[0055] The proportion of (meth)acrylic acid ester monomer units contained in the core polymer is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, and preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less, based on 100% by mass of all monomer units contained in the core polymer. If the proportion of (meth)acrylic acid ester monomer units contained in the core polymer is equal to or greater than the lower limit, the room temperature adhesion of the functional layer can be further improved. Furthermore, if the proportion of (meth)acrylic acid ester monomer units contained in the core polymer is equal to or less than the upper limit, the blocking resistance of the functional layer can be improved.

[0056] [Shell Portion] The monomer unit contained in the polymer of the shell portion is not particularly limited, but an aromatic vinyl monomer unit is preferred. The polymer of the shell portion may contain only one type of monomer unit or multiple types of monomer units.

[0057] -Aromatic vinyl monomer unit- Examples of aromatic vinyl monomers that can form the aromatic vinyl monomer unit in the polymer of the shell portion include the same ones as those described above. These may be used alone or in combination of two or more. Among these, styrene is preferred.

[0058] The proportion of aromatic vinyl monomer units contained in the shell polymer is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass (i.e., the shell polymer contains only aromatic vinyl monomer units), assuming that the total monomer units contained in the shell polymer is 100% by mass. If the proportion of aromatic vinyl monomer units in the shell polymer is equal to or greater than the above lower limit, the glass transition temperature of the shell polymer increases, and the blocking resistance of the functional layer can be improved.

[0059] —Other Monomer Units— The monomer units (other monomer units) other than the aromatic vinyl monomer units that the shell polymer may contain are not particularly limited, and examples thereof include the above-mentioned crosslinkable monomer units and (meth)acrylic acid ester monomer units.

[0060] When the particulate polymer A has a core-shell structure, the mass ratio of the core portion to the shell portion (core portion / shell portion) is preferably 0.1 / 99.9 or more, more preferably 1 / 99 or more, even more preferably 10 / 90 or more, particularly preferably 50 / 50 or more, and is preferably 99.9 / 0.1 or less, more preferably 99 / 1 or less, and even more preferably 95 / 5 or less. When the mass ratio of the core portion to the shell portion is the above-mentioned lower limit or more, the room temperature adhesiveness of the functional layer can be further improved. On the other hand, when the mass ratio of the core portion to the shell portion is the above-mentioned upper limit or less, the blocking resistance of the functional layer can be improved.

[0061] <<Properties of Particulate Polymer A>> [Volume Average Particle Diameter] The particulate polymer A used in the present invention must have a volume average particle diameter of 0.75 μm or more and 17.5 μm or less. The volume average particle diameter of the particulate polymer A is preferably 1 μm or more, more preferably 1.5 μm or more, even more preferably 2.5 μm or more, particularly preferably 3 μm or more, preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less. If the volume average particle diameter of the particulate polymer A is 0.75 μm or more, the room temperature adhesiveness of the functional layer can be improved and the internal resistance of the electrochemical element can be reduced. On the other hand, if the volume average particle diameter of the particulate polymer A is 17.5 μm or less, the blocking resistance of the functional layer can be improved. The volume average particle diameter of the particulate polymer A can be adjusted by changing the type and amount of the metal hydroxide used in preparing the particulate polymer A, as well as the preparation method and preparation conditions of the particulate polymer A.

[0062] [THF Elution Amount] The particulate polymer A must have a THF elution amount of 0.05% by mass or more and 60% by mass or less. The THF elution amount is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, still more preferably 5% by mass or more, particularly preferably 10% by mass or more, preferably 50% by mass or less, more preferably 47% by mass or less, and even more preferably 45% by mass or less. If the THF elution amount of the particulate polymer A is 0.05% by mass or more, the room temperature adhesion of the functional layer can be improved. Furthermore, if the THF elution amount of the particulate polymer A is 60% by mass or less, the elution of the particulate polymer A into the electrolyte can be suppressed, and the internal resistance of the electrochemical device can be reduced. The THF elution amount of the particulate polymer A can be adjusted, for example, by changing the type and / or amount of the crosslinkable monomer used to prepare the particulate polymer A. Specifically, by increasing the amount of the crosslinkable monomer used to prepare the particulate polymer A, the amount of THF eluted decreases, and by decreasing the amount of the crosslinkable monomer, the amount of THF eluted increases.

[0063] [Storage Modulus] The particulate polymer A must have a storage modulus of 35 MPa or less at 25°C. The storage modulus at 25°C is preferably less than 30 MPa, more preferably 20 MPa or less, even more preferably 10 MPa or less, particularly preferably 5 MPa or less, preferably 0.05 MPa or more, and more preferably 0.1 MPa or more. If the particulate polymer A has a storage modulus of 35 MPa or less at 25°C, the room temperature adhesiveness of the functional layer can be improved. Furthermore, if the particulate polymer A has a storage modulus of 0.05 MPa or more at 25°C, the blocking resistance of the functional layer can be improved and the internal resistance of the electrochemical element can be further reduced. The storage modulus of the particulate polymer A can be adjusted, for example, by changing the type and / or amount of the monomer used to prepare the particulate polymer A.

[0064] [Number Average Molecular Weight of THF-Soluble Component] The number average molecular weight of the THF-soluble component of the particulate polymer A is preferably 500 or more, more preferably 750 or more, even more preferably 1,000 or more, even more preferably 2,500 or more, particularly preferably 5,000 or more, and preferably 500,000 or less, more preferably 400,000 or less, even more preferably 300,000 or less, and particularly preferably 200,000 or less. If the number average molecular weight of the THF-soluble component of the particulate polymer A is equal to or greater than the above-mentioned lower limit, elution of the particulate polymer A into the electrolyte can be suppressed, and the room temperature adhesiveness of the functional layer can be further improved. Furthermore, if the number average molecular weight of the THF-soluble component of the particulate polymer A is equal to or less than the above-mentioned upper limit, an increase in the viscosity of the electrolyte can be suppressed, and the internal resistance of the electrochemical device can be further reduced. The number average molecular weight of the THF-soluble component of the particulate polymer A can be adjusted, for example, by changing the preparation method and preparation conditions of the particulate polymer A.

[0065] [Glass transition temperature] The glass transition temperature of the particulate polymer A is preferably -50°C or higher, more preferably -45°C or higher, even more preferably -40°C or higher, and preferably 95°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, even more preferably 40°C or lower, and particularly preferably 25°C or lower. When the glass transition temperature of the particulate polymer A is equal to or higher than the above lower limit, the blocking resistance of the functional layer can be improved. When the glass transition temperature of the particulate polymer A is equal to or lower than the above upper limit, the room temperature adhesiveness of the functional layer can be further improved. The glass transition temperature of the particulate polymer A can be adjusted, for example, by changing the type and / or amount of the monomer used to prepare the particulate polymer A.

[0066] [Electrolyte Swelling Degree] The electrolyte swelling degree of the particulate polymer A is preferably 100% or more, more preferably 125% or more, even more preferably 150% or more, and preferably 500% or less, more preferably 400% or less, even more preferably 300% or less, and particularly preferably 210% or less. When the electrolyte swelling degree of the particulate polymer A is equal to or greater than the above lower limit, the room temperature adhesion of the functional layer can be further improved. Furthermore, when the electrolyte swelling degree of the particulate polymer A is equal to or less than the above upper limit, the internal resistance of the electrochemical element can be further reduced. Note that the electrolyte swelling degree of the particulate polymer A can be adjusted, for example, by changing the type and / or amount of the crosslinkable monomer used to prepare the particulate polymer A. Specifically, the electrolyte swelling degree decreases when the amount of the crosslinkable monomer used to prepare the particulate polymer A is increased, and increases when the amount is decreased.

[0067] <<Preparation of Particulate Polymer A>> The particulate polymer A can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. Here, the proportion of each monomer in the monomer composition is usually the same as the proportion of each monomer unit in the particulate polymer A.

[0068] The polymerization method is not particularly limited, and any of methods such as suspension polymerization, emulsion polymerization aggregation, and pulverization can be used. Among these, suspension polymerization and emulsion polymerization aggregation are preferred, and suspension polymerization is more preferred. Furthermore, any of reactions such as radical polymerization and living radical polymerization can be used as the polymerization reaction.

[0069] Further, the monomer composition used in preparing the particulate polymer A may contain other additives such as a chain transfer agent, a polymerization regulator, a polymerization reaction retarder, a reactive fluidizing agent, a filler, a flame retardant, an antiaging agent, and a colorant in any blending amount.

[0070] Here, as an example, a method for preparing the particulate polymer A having a core-shell structure by suspension polymerization will be described.

[0071] [Preparation of Particulate Polymer A by Suspension Polymerization Method] (1) Preparation of Core-Forming Monomer Composition First, the monomers constituting the core polymer and other compounding ingredients added as needed are mixed to prepare the core-forming monomer composition.

[0072] (2) Formation of droplets Next, the core-forming monomer composition is dispersed in water, a polymerization initiator is added, and then droplets of the core-forming monomer composition are formed. The method for forming the droplets is not particularly limited, and for example, the droplets can be formed by shearing and stirring water containing the monomer composition using a disperser such as an emulsifying disperser.

[0073] Examples of the polymerization initiator include oil-soluble polymerization initiators such as t-butylperoxy-2-ethylhexanoate, azobisisobutyronitrile, etc. 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 it is dispersed in water.

[0074] From the viewpoint of stabilizing the formed droplets of the monomer composition in water, it is preferable to add a dispersion stabilizer to water to form the droplets of the monomer composition. In this case, for example, a metal hydroxide such as magnesium hydroxide, or sodium dodecylbenzenesulfonate can be used as the dispersion stabilizer. Here, the dispersion stabilizer may be added in the form of a colloidal dispersion in which the dispersion stabilizer is dispersed in water.

[0075] (3) Polymerization After droplets of the core-forming monomer composition are formed, the water containing the formed droplets is heated to initiate polymerization, thereby forming a particulate polymer constituting the core portion in the water. Furthermore, by polymerizing a monomer that forms the shell portion in the presence of this particulate polymer that forms the core portion, the particulate polymer A having the core-shell structure described above can be obtained. The polymerization of the monomer that forms the shell portion can be carried out, for example, by precipitating the particulate polymer that forms the core portion by centrifugation, redispersing the resulting wet cake in water, adding a polymerization initiator and a monomer that forms the shell portion, and then heating the mixture. Examples of the polymerization initiator used in this process include water-soluble thermal radical polymerization initiators such as 2,2'-azobis(2-methylpropionamide) dihydrochloride.

[0076] <Particulate polymer B> The particulate polymer B, which may be optionally contained in the composition for functional layer of the present invention, is a component that functions as a binder and is usually composed of a polymer having binding ability. When the composition for functional layer contains the particulate polymer B, the room temperature adhesiveness of the functional layer can be further improved. The particulate polymer B is a component different from the particulate polymer A described above and is preferably water-insoluble.

[0077] Here, the particulate polymer B is not particularly limited as long as it is a particulate polymer that is different from the above-mentioned particulate polymer A and is water-insoluble and dispersible in a dispersion medium such as water, but for example, a conjugated diene polymer or an acrylic polymer can be used. Among these, it is preferable to use an acrylic polymer. Furthermore, the particulate polymer B differs from the above-mentioned particulate polymer A in at least one of the volume average particle size, the amount of elution into THF, and the storage modulus at 25°C. That is, the particulate polymer B does not satisfy at least one of the above-mentioned physical property values ​​(volume average particle size, the amount of elution into THF, and the storage modulus at 25°C) that the particulate polymer A must satisfy. Note that the conjugated diene polymer refers to a polymer containing a conjugated diene monomer unit. Specific examples of conjugated diene polymers include, but are not limited to, copolymers containing aromatic vinyl monomer units and aliphatic conjugated diene monomer units, such as styrene-butadiene copolymer (SBR), butadiene rubber (BR), acrylic rubber (NBR) (copolymers containing acrylonitrile units and butadiene units), and hydrogenated products thereof. Furthermore, the acrylic polymer refers to a polymer containing (meth)acrylic acid ester monomer units. These may be used alone or in combination of two or more types in any ratio.

[0078] The acrylic polymer that can be preferably used as the particulate polymer B is not particularly limited, and examples thereof include a polymer containing the above-mentioned crosslinkable monomer unit and (meth)acrylic acid ester monomer unit, and an acid group-containing monomer unit described below.

[0079] Examples of the acid group-containing monomer capable of forming the acid group-containing monomer unit include a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, and a monomer having a phosphoric acid group.

[0080] Examples of the monomer having a carboxylic acid group include monocarboxylic acids and dicarboxylic acids. Examples of the monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.

[0081] Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, (meth)acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, etc. In this specification, "(meth)allyl" means allyl and / or methallyl.

[0082] Examples of the monomer having a phosphate group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, etc. In this specification, "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0083] The above-mentioned acid group-containing monomers may be used alone or in any combination of two or more kinds in any ratio. Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferred, acrylic acid and methacrylic acid are more preferred, and methacrylic acid is even more preferred.

[0084] The proportion of (meth)acrylic acid ester monomer units in the acrylic polymer is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 58% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less. If the proportion of (meth)acrylic acid ester monomer units in the acrylic polymer is equal to or greater than the above-mentioned lower limit, the room temperature adhesion of the functional layer can be further improved. Furthermore, if the proportion of (meth)acrylic acid ester monomer units in the acrylic polymer is equal to or less than the above-mentioned upper limit, the blocking resistance of the functional layer can be improved.

[0085] The proportion of the acid group-containing monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. If the proportion of the acid group-containing monomer units in the acrylic polymer is equal to or greater than the above-mentioned lower limit, the dispersibility of the particulate polymer B in the functional layer composition and in the functional layer can be improved, and the room temperature adhesiveness of the functional layer can be further improved. Furthermore, if the proportion of the acid group-containing monomer units in the acrylic polymer is equal to or less than the above-mentioned upper limit, the residual moisture content of the functional layer can be reduced, and the blocking resistance of the functional layer can be improved.

[0086] The proportion of crosslinkable monomer units in the acrylic polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 3% by mass or less, more preferably 2.5% by mass or less. If the proportion of crosslinkable monomer units in the acrylic polymer is equal to or greater than the lower limit, the blocking resistance of the functional layer can be improved. Furthermore, if the proportion of crosslinkable monomer units in the acrylic polymer is equal to or less than the upper limit, the room temperature adhesion of the functional layer can be further improved.

[0087] The acrylic polymer may contain monomer units (other monomer units) other than the (meth)acrylic acid ester monomer units, acid group-containing monomer units and crosslinkable monomer units. and vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; vinyl ketone monomers such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; and heterocycle-containing vinyl compound monomers such as N-vinylpyrrolidone, vinylpyridine, and vinylimidazole. Among these, as the other monomer, a nitrile group-containing monomer is preferred, and acrylonitrile is more preferred. Note that these other monomers may be used alone or in combination of two or more types in any ratio. The content ratio of the other monomer units in the acrylic polymer may be appropriately adjusted.

[0088] <<Properties of Particulate Polymer B>> [Glass Transition Temperature] The glass transition temperature (Tg) of the particulate polymer B is preferably −100° C. or higher, more preferably −90° C. or higher, even more preferably −80° C. or higher, and is preferably less than 30° C., more preferably 20° C. or lower, and even more preferably 15° C. or lower. When the glass transition temperature of the particulate polymer B is equal to or higher than the above lower limit, the room temperature adhesiveness of the functional layer can be further improved. In addition, the blocking resistance of the functional layer can be improved. On the other hand, when the glass transition temperature of the particulate polymer B is equal to or lower than the above upper limit, the flexibility of the functional layer can be increased.

[0089] [Volume average particle diameter] The volume average particle diameter of the particulate polymer B is preferably 0.05 μm or more, more preferably 0.1 μm or more, and preferably less than 0.75 μm, more preferably 0.5 μm or less. If the volume average particle diameter of the particulate polymer B is 0.05 μm or more, the dispersibility of the particulate polymer B can be improved. If the volume average particle diameter of the particulate polymer B is less than 0.75 μm, the binding property of the particulate polymer B can be improved. The volume average particle diameter of the particulate polymer B can be measured in the same manner as the volume average particle diameter of the particulate polymer A described above.

[0090] When the composition for functional layer contains particulate polymer B, the mass ratio of particulate polymer A to particulate polymer B in the composition for functional layer (particulate polymer A / particulate polymer B) is preferably 1 / 99 or more, more preferably 5 / 95 or more, even more preferably 10 / 90 or more, particularly preferably 50 / 50 or more, and is preferably 99 / 1 or less, more preferably 95 / 5 or less, and even more preferably 90 / 10 or less. If the mass ratio of particulate polymer A to particulate polymer B is the above-mentioned lower limit or more, the room temperature adhesion of the functional layer can be further improved. Furthermore, if the mass ratio of particulate polymer A to particulate polymer B is the above-mentioned upper limit or less, the internal resistance of the electrochemical element can be further reduced.

[0091] When the composition for functional layer further contains non-conductive heat-resistant particles described below, the content of the particulate polymer B in the composition for functional layer is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, particularly preferably 3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the non-conductive heat-resistant particles. If the content of the particulate polymer B is not less than the above lower limit, the room temperature adhesion of the functional layer can be further improved. On the other hand, if the content of the particulate polymer B is not more than the above upper limit, the internal resistance of the electrochemical element can be further reduced.

[0092] <<Preparation of Particulate Polymer B>> The particulate polymer B is not particularly limited, and can be prepared, for example, by polymerizing a monomer composition containing the above-mentioned monomers 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 particulate polymer B.

[0093] The polymerization method and polymerization reaction are not particularly limited, and for example, the polymerization methods and polymerization reactions exemplified as the polymerization methods for the particulate polymer A described above can be used.

[0094] <Dispersion Medium> The composition for a functional layer of the present invention typically contains a dispersion medium. Examples of the dispersion medium include water and organic solvents such as esters, ketones, and alcohols. These may be used alone or in combination of two or more. Among these, water is preferred. That is, the composition for a functional layer of the present invention is preferably a slurry composition in which components such as the particulate polymer A described above are dispersed in a dispersion medium containing water. The proportion of water in the dispersion medium is preferably 50% by volume or more, more preferably 70% by volume or more, even more preferably 90% by volume or more, even more preferably 99% by volume or more, and particularly preferably 100% by volume (i.e., the composition for a functional layer contains only water as the dispersion medium), based on the total amount of the dispersion medium being 100% by volume.

[0095] <Dispersant> The composition for functional layer of the present invention preferably further contains a dispersant. If the composition for functional layer further contains a dispersant, the room temperature adhesion of the functional layer can be further improved.

[0096] Preferred examples of dispersants include polycarboxylic acids such as polyacrylic acid, polymethacrylic acid, and alginic acid. The polycarboxylic acids may form salts with alkali metals, ammonia, or the like. Among these, polyacrylic acid and its salts are preferred. The dispersants may be used singly or in combination of two or more in any ratio.

[0097] When the composition for functional layer contains a dispersant, the amount of dispersant in the composition for functional layer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the particulate polymer A. When the amount of dispersant in the composition for functional layer is equal to or greater than the above-mentioned lower limit, uneven distribution of the particulate polymer A and the particulate polymer B in the functional layer can be suppressed, and the room temperature adhesion of the functional layer can be further improved. Furthermore, when the amount of dispersant in the composition for functional layer is equal to or less than the above-mentioned upper limit, the internal resistance of the electrochemical element can be further reduced.

[0098] <Non-conductive heat-resistant particles> The composition for a functional layer of the present invention preferably further contains non-conductive heat-resistant particles (hereinafter also referred to as "heat-resistant particles"). If the composition for a functional layer further contains heat-resistant particles, the heat resistance of the functional layer can be improved. In this specification, "non-conductive heat-resistant particles" means non-conductive fine particles having a heat-resistant temperature of 200°C or higher, and "heat-resistant temperature" means a temperature at which no substantial physical changes such as thermal deformation occur.

[0099] The heat-resistant particles are not particularly limited as long as they are fine particles that have a heat-resistant temperature of 200° C. or higher, are electrochemically stable, and have electrical insulation properties, but inorganic particles are preferred. Since inorganic particles have a relatively large specific gravity, when a functional layer is formed by, for example, applying a functional layer composition containing inorganic particles to a substrate, the particulate polymer A is more likely to protrude from the inorganic particles on the thickness direction surface of the functional layer, and as a result, the room temperature adhesion of the functional layer can be further improved.

[0100] Here, the inorganic particle material is preferably one that is stable in the environment in which the electrochemical element is used and is electrochemically stable, and examples thereof include aluminum oxide (alumina), aluminum oxide hydrate (boehmite (AlOOH)), gibbsite (Al(OH ３ )), silicon oxide, magnesium oxide (magnesia), magnesium hydroxide, calcium oxide, titanium oxide (titania), barium titanate (BaTiO ３Examples of inorganic particles include oxide particles such as zirconium oxide (ZrO), alumina-silica composite oxide, etc.; nitride particles such as aluminum nitride and boron nitride; covalently bonded crystalline particles such as silicon and diamond; sparingly soluble ionic crystalline particles such as barium sulfate, calcium fluoride, and barium fluoride; and clay fine particles such as talc and montmorillonite. Among these, aluminum oxide, aluminum oxide hydrate (boehmite), magnesium hydroxide, and barium sulfate are more preferred, with aluminum oxide being even more preferred. Furthermore, these particles may be subjected to element substitution, surface treatment, solid solution formation, etc., as necessary. These inorganic particles may be used alone or in combination of two or more types in any ratio.

[0101] <<Volume Average Particle Diameter of Heat-Resistant Particles>> The volume average particle diameter (D50) of the heat-resistant particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.25 μm or more, and preferably 1.5 μm or less, more preferably 1.0 μm or less, and even more preferably 0.8 μm or less. When the volume average particle diameter of the heat-resistant particles is equal to or greater than the above-mentioned lower limit, the heat-resistant particles are densely packed in the functional layer. This further suppresses a decrease in ionic conductivity in the functional layer, thereby improving the electrochemical characteristics (particularly, output characteristics) of the electrochemical element. On the other hand, when the volume average particle diameter of the heat-resistant particles is equal to or less than the above-mentioned upper limit, the functional layer can exhibit excellent heat resistance even when the functional layer is thin, thereby increasing the capacity of the electrochemical element. The volume average particle diameter of the heat-resistant particles can be measured by laser diffraction.

[0102] <<Mixing Ratio of Heat-Resistant Particles and Particulate Polymer A>> The mixing ratio of the heat-resistant particles to the particulate polymer A in the composition for the functional layer, expressed as a mass ratio (heat-resistant particles / particulate polymer A), is preferably 40 / 60 or more, more preferably 50 / 50 or more, and even more preferably 60 / 40 or more, and is preferably 99 / 1 or less, more preferably 90 / 10 or less, and even more preferably 80 / 20 or less. If the mass ratio of the heat-resistant particles to the particulate polymer A is within the above range, the balance between the heat resistance and room temperature adhesion of the functional layer is better.

[0103] <Other Components> The composition for functional layer of the present invention may contain any other components in addition to the above-mentioned particulate polymer A, particulate polymer B, dispersion medium, dispersant, and heat-resistant particles. The 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 thickeners such as carboxymethyl cellulose and hydroxypropyl methyl cellulose; wetting agents; and dispersion stabilizers such as sodium dodecylbenzenesulfonate. These other components may be used alone or in combination of two or more.

[0104] <Properties of the Functional Layer Composition> <<pH>> When the functional layer composition of the present invention contains water as a dispersion medium, the pH of the functional layer composition is preferably 3.0 or higher, more preferably 4.0 or higher, even more preferably 5.0 or higher, and preferably 12.0 or lower, more preferably 10.0 or lower, and even more preferably 9.0 or lower. If the pH of the functional layer composition is above the above lower limit, the room temperature adhesion of the functional layer can be further improved. Furthermore, if the pH of the functional layer composition is below the above upper limit, hydrolysis of thickeners such as carboxymethyl cellulose can be suppressed, thereby improving the dispersibility of the functional layer composition. The pH of the functional layer composition can be adjusted by adding a known acidic or basic compound.

[0105] <Method for preparing composition for functional layer> The composition for functional layer is not particularly limited, and can be prepared, for example, by mixing the above-mentioned particulate polymer A with the particulate polymer B, dispersion medium, dispersant, heat-resistant particles, and other components that are used as needed. Note that, when the particulate polymer A or the particulate polymer B is prepared by polymerizing a monomer composition in an aqueous solvent, the particulate polymer A or the particulate polymer B may be mixed with other components as is in the form of an aqueous dispersion. Furthermore, when the particulate polymer A or the particulate polymer B is mixed in the form of an aqueous dispersion, the water in the aqueous dispersion may be used as a dispersion medium.

[0106] Here, the method for mixing the above-mentioned components is not particularly limited, but in order to efficiently disperse each component, it is preferable to use a disperser as a mixing device. The disperser is preferably a device that can uniformly disperse and mix the above-mentioned components. Examples of dispersers include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, and a planetary mixer.

[0107] (Laminate for electrochemical device) The laminate of the present invention includes a substrate and a functional layer formed on the substrate, the functional layer being formed using the functional layer composition of the present invention. Since the laminate of the present invention includes a functional layer formed using the functional layer composition described above, the internal resistance of the electrochemical device can be reduced.

[0108] <Substrate> The substrate is not particularly limited, and for example, when a functional layer is used as a component constituting part of a separator, a separator substrate can be used as the substrate, and when a functional layer is used as a component constituting part of an electrode, an electrode substrate obtained by forming an electrode mixture layer on a current collector can be used as the substrate. There are no particular limitations on the use of the laminate obtained by forming a functional layer on a substrate using a functional layer composition, and for example, a functional layer can be formed on a separator substrate or the like and used as an electrochemical element component such as a separator, or a functional layer can be formed on an electrode substrate and used as an electrode,

[0109] <<Separator Substrate>> The separator substrate on which the functional layer is formed is not particularly limited, and for example, the one described in JP 2012-204303 A can be used. Among these, a microporous film made of a polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred because it allows the thickness of the entire separator to be thin, thereby increasing the proportion of electrode active material in the electrochemical device and increasing the capacity per volume. Note that the separator substrate may also include, as part thereof, any layer other than the functional layer that can exhibit the desired function.

[0110] <<Electrode Substrate>> The electrode substrate (positive electrode substrate and negative electrode substrate) is not particularly limited, but examples include electrode substrates in which an electrode mixture layer is formed on a current collector. Here, the current collector, the electrode active material (positive electrode active material, negative electrode active material) and the electrode mixture layer binder (positive electrode mixture layer binder, negative electrode mixture layer binder), as well as the method of forming the electrode mixture layer on the current collector, can be known methods, such as those described in JP 2013-145763 A. The electrode substrate may include, as a part thereof, any layer having a desired function other than the functional layer.

[0111] <Functional layer> The functional layer can be formed on the above-mentioned substrate using the functional layer composition of the present invention. Here, the functional layer contains at least the above-mentioned particulate polymer A, and optionally contains particulate polymer B, a dispersant, heat-resistant particles and other components. Note that each component contained in the functional layer is the same as that contained in the functional layer composition, and the preferred ratio of each component is the same as the preferred ratio of each component in the functional layer composition.

[0112] <<Method for forming a functional layer>> The method for forming a functional layer on a substrate using a functional layer composition is not particularly limited, and examples thereof include: 1) a method in which the functional layer composition is applied to the surface of the substrate described above and then dried; 2) a method in which the substrate described above is immersed in the functional layer composition and then dried; and 3) a method in which the functional layer composition is applied to a release substrate and dried to form a functional layer, and the resulting functional layer is then transferred to the surface of the substrate described above. Note that the functional layer may be formed on only one side of the substrate, or on both sides of the substrate. Here, the release substrate is not particularly limited, and known release substrates can be used.

[0113] Among these, the method 1) is preferred because it is easy to control the thickness of the functional layer. The method 1) may include, for example, a step of applying a functional layer composition onto a substrate (application step) and a step of drying the functional layer composition applied onto the substrate to form a functional layer (functional layer formation step).

[0114] [Coating process] In the coating process, the method for coating the functional layer composition onto the substrate is not particularly limited, and examples thereof include the doctor blade method, reverse roll method, direct roll method, gravure method, extrusion method, and brush coating method.

[0115] [Functional layer forming step] In the functional layer forming step, the method for drying the functional layer composition on the substrate is not particularly limited and can be a known method, such as drying with warm air, hot air, or low-humidity air, vacuum drying, or drying by irradiation with infrared rays or electron beams, etc. The drying conditions are not particularly limited, but the drying temperature is preferably 50°C or higher and 150°C or lower, and the drying time is preferably 1 minute or higher and 30 minutes or lower.

[0116] Here, the functional layer composition of the present invention described above may be a first functional layer composition containing particulate polymer A but not containing heat-resistant particles, or a second functional layer composition containing heat-resistant particles in addition to particulate polymer A. When a functional layer is formed on a substrate using the first functional layer composition, an adhesive layer can be obtained as the functional layer. When a functional layer is formed on a substrate using the second functional layer composition, a single layer can be obtained as the functional layer, simultaneously functioning as a heat-resistant layer that enhances the heat resistance of the substrate and as an adhesive layer that firmly bonds components together. Furthermore, a laminate including a functional layer formed using the second functional layer composition can be produced in fewer steps and in less time than a substrate including a conventional heat-resistant layer and an adhesive layer, resulting in high productivity.

[0117] <<Functional Layer Thickness>> The thickness of the functional layer formed using the composition for electrochemical device functional layers of the present invention is preferably 0.5 μm or more and preferably 5 μm or less. If the thickness of the functional layer is equal to or greater than the above-mentioned lower limit, the room temperature adhesion of the functional layer can be further improved. Furthermore, if the thickness of the functional layer is equal to or less than the above-mentioned upper limit, the blocking resistance of the functional layer can be improved.

[0118] (Electrochemical element) The electrochemical element of the present invention comprises an electrode and a separator, and is characterized in that the electrochemical element of the present invention comprises the above-described laminate of the present invention as at least one of the electrode and the separator. The electrochemical element of the present invention has low internal resistance because the above-described laminate of the present invention is used as at least one of the element components of the electrode and the separator.

[0119] The electrochemical device of the present invention is not particularly limited, and may be, for example, a lithium ion secondary battery, an electric double layer capacitor, or a lithium ion capacitor, and is preferably a lithium ion secondary battery.

[0120] Hereinafter, a lithium ion secondary battery will be taken as an example of the electrochemical element of the present invention, and a case will be described in which the above-described laminate of the present invention is used as a separator of the lithium ion secondary battery, but the electrochemical element of the present invention is not limited thereto.

[0121] <Positive Electrode and Negative Electrode> As the positive electrode and negative electrode, electrodes made of the known electrode substrates (positive electrode substrate and negative electrode substrate) described above in the section "Substrate" can be used.

[0122] <Electrolyte> As the electrolyte, an organic electrolyte solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. For example, in a lithium ion secondary battery, a lithium salt is used as the supporting electrolyte. For example, LiPF ６ , LiAsF ６ , LiBF ４ , LiSbF ６ , LiAlCl ４ , LiClO ４ , C.F. 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 ２Among them, LiPF is preferred because it is easily soluble in solvents and shows a high degree of dissociation. ６ , LiClO ４ , C.F. ３ SO ３ Li is preferred. The electrolyte may be used alone or in combination of two or more. Generally, the lithium ion conductivity tends to increase as the supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0123] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but for example, in lithium ion secondary batteries, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (ethyl methyl carbonate (EMC)), vinylene carbonate, etc.; esters such as γ-butyrolactone and methyl formate, etc.; ethers such as 1,2-dimethoxyethane and tetrahydrofuran, etc.; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide, etc. are preferably used. Furthermore, a mixture of these solvents may also be used.

[0124] Among these, carbonates are preferred because they have a high dielectric constant and a wide stable potential range. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted by the type of solvent. The concentration of the electrolyte in the electrolyte solution can be adjusted as appropriate. Known additives may also be added to the electrolyte solution.

[0125] <Method for Manufacturing Electrochemical Element> The method for manufacturing the electrochemical element of the present invention is not particularly limited. For example, the lithium ion secondary battery, which is an example of the electrochemical element of the present invention described above, can be manufactured by stacking a positive electrode and a negative electrode with a separator interposed therebetween, rolling or folding the stack as necessary, placing the stack in a battery container, injecting an electrolyte into the battery container, and sealing the container. At least one of the positive electrode, negative electrode, and separator is the laminate of the present invention. Furthermore, the battery container may contain an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like, as necessary, to prevent pressure buildup within the battery and overcharging and discharging. The shape of the battery may be any shape, such as a coin type, button type, sheet type, cylindrical type, rectangular type, or flat type.

[0126] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. Furthermore, in a polymer produced by polymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer usually coincides with the ratio (feed ratio) of that certain monomer to all monomers used in the polymerization of the polymer, unless otherwise specified. In the examples and comparative examples, measurements and evaluations of various attributes were carried out as follows.

[0127] <Volume Average Particle Diameter of Particulate Polymer A> The aqueous dispersion containing particulate polymer A prepared in the Examples and Comparative Examples was placed in a beaker so that the solid content was 0.1 g, and 0.1 mL of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fujifilm Corporation, product name "Dry-Well") was added. 10 to 30 mL of a diluent (manufactured by Beckman Coulter, product name "Isoton II") was further added to the beaker, and the mixture was dispersed for 3 minutes using a 20 W (Watt) ultrasonic disperser to obtain a measurement sample. Thereafter, a particle size distribution (volume basis) of the measurement sample was obtained using a particle size analyzer (manufactured by Beckman Coulter, product name "Multisizer") under the conditions of an aperture diameter of 20 μm, medium: Isoton II, and number of particles measured: 100,000. In the obtained particle size distribution, the volume average particle diameter was determined as the particle diameter (D50) at which the cumulative volume calculated from the smallest diameter side reached 50%. <Glass Transition Temperature> The aqueous dispersions containing particulate polymer A prepared in the Examples and Comparative Examples were dried to obtain powder samples, which were used as measurement samples. 10 mg of the measurement sample was weighed into an aluminum pan, and measurement was carried out using a differential thermal analyzer (manufactured by SII Nanotechnology Inc., product name "EXSTAR DSC6220") at a measurement temperature range of -100°C to 500°C at a heating rate of 10°C / min under the conditions specified in JIS Z 8703 to obtain a differential scanning calorimetry (DSC) curve. An empty aluminum pan was used as a reference. During this heating process, the glass transition temperature (°C) was determined as the intersection point between the baseline immediately before the appearance of an endothermic peak in the DSC curve at which the differential signal (DDSC) was 0.05 mW / min / mg or more and the tangent to the DSC curve at the first inflection point that appeared after the endothermic peak. <Storage Modulus> The aqueous dispersions containing particulate polymer A prepared in the Examples and Comparative Examples were dried to obtain powder samples. 10 mg of the measurement sample was weighed into an aluminum pan, and measurement was carried out using a differential thermal analyzer (manufactured by SII Nanotechnology Inc., product name "EXSTAR DSC6220") at a measurement temperature range of -100°C to 500°C at a heating rate of 10°C / min under the conditions specified in JIS Z 8703 to obtain a differential scanning calorimetry (DSC) curve. ２The solid content was weighed out to 0.48 g and placed in an aluminum cup, followed by air drying. After air drying, a film composed of particulate polymer A having a thickness of 70 to 80 μm was obtained. The obtained film was punched out to a diameter of 12 mm, and this was used as a measurement sample. For samples that did not form a film but turned into powder after air drying, approximately 0.1 g of the air-dried powder was weighed into a 12 mm diameter tablet press and pressed at 9 kN for 10 seconds to form a tablet (12 mm diameter x 75 μm thickness), which was used as a measurement sample. Then, using a viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR302") as a dynamic viscoelasticity measuring device, the storage modulus (MPa) was measured at parallel plates (8 mm diameter), strain 0.01%, frequency 1 Hz, and 25°C. <Electrolyte Swelling Degree> The aqueous dispersion containing the particulate polymer A prepared in the Examples and Comparative Examples was dropped into a polytetrafluoroethylene petri dish so that the solid content was 1.0 g, and dried at 25 ° C. for 48 hours to prepare a film. For particulate polymer A having a glass transition temperature of 25 ° C. or higher, 0.2 ± 0.05 g of the dried sample was pressed at a temperature of 200 ° C. and a pressure of 5 MPa for 2 minutes to prepare a film. The prepared film was cut into 1.5 mm square film pieces, and 0.2 ± 0.05 g was precisely weighed. The mass of the precisely weighed film piece was designated W0. Next, the precisely weighed film piece was immersed in 50 mL of electrolyte at 60 ° C. for 72 hours. Thereafter, the film piece was pulled out of the electrolyte, the electrolyte on the surface of the film piece was wiped off, and its mass (mass of the film piece after the immersion test) W1 was measured. Using the measured weights W0 and W1, the electrolyte swelling degree S (%) was calculated as S = (W1 / W0) × 100. The electrolyte was a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (weight mixing ratio: EC / EMC = 3 / 7) to which 2% by volume (solvent ratio) of vinylene carbonate was added, and LiPF6 was used as a supporting electrolyte. ６A solution of the above at a concentration of 1 mol / L was used. <Amount of THF Elution> The aqueous dispersion containing the particulate polymer A prepared in the Examples and Comparative Examples was dropped into a petri dish so as to give a solid content of 1.5 g, dried in an environment of 23 to 27°C for 24 hours, and further dried at 110°C for 1 hour to prepare a film. For particulate polymer A having a glass transition temperature of 25°C or higher, 0.2±0.05 g of the dried sample was pressed at a temperature of 200°C and a pressure of 5 MPa for 2 minutes to prepare a film. The prepared film was cut into film pieces of 2.0 to 3.0 mm square, and 0.3±0.05 g was precisely weighed out. The mass of the precisely weighed film piece was designated W2. Next, the precisely weighed film piece was immersed in 80 mL of tetrahydrofuran (THF) at 25°C for 24 hours. Thereafter, the film piece was pulled out from the THF and vacuum-dried at 105°C for 3 hours, and its mass (mass of the insoluble portion) W3 was measured. Then, the amount of THF elution (%) was calculated according to the following formula: Amount of THF elution (%) = (W2 - W3) / W2 × 100 <Number average molecular weight of THF eluted component> In the measurement of the "amount of THF elution" described above, the THF after immersing the film piece was recovered and dried. The resin obtained by drying was recovered, and 2 mg of the recovered resin was dissolved in 5 g of THF, to which 0.2 g of cyclohexane was added, and this was used as a measurement sample. Then, gel permeation chromatography (GPC) was performed to measure the number average molecular weight of the THF eluted component of the particulate polymer A. The GPC measurement conditions were as follows. Standard polystyrene (TSKgel (registered trademark) standard Polystyrene) was used to prepare a calibration curve, and the number average molecular weight was determined.Apparatus name: HLC-8320 (manufactured by Tosoh Corporation) Columns: TSKgel Super H2000 (inner diameter 6 mm, length 150 mm, pore diameter 2 nm), TSKgel Super H4000 (inner diameter 6 mm, length 150 mm, pore diameter 20 nm), TSKgel Super H5000 (inner diameter 6 mm, length 150 mm, pore diameter 65 nm) (all manufactured by Tosoh Corporation) Detector: Differential Refractometer HLC-8320 (manufactured by Tosoh Corporation) <pH> The pH at 25°C of the functional layer compositions prepared in the examples and comparative examples was measured using a benchtop pH meter (manufactured by Horiba, Ltd., product name "LAQUA-PH-SE"). <Blocking Resistance> A polyethylene microporous membrane (thickness: 12 μm) was prepared as a separator substrate. The functional layer composition prepared in each of the examples and comparative examples was applied to one side of the separator substrate using a bar coater. The separator substrate coated with the functional layer composition was then dried at 50°C for 10 minutes to produce a separator (laminate) with a functional layer having a thickness of 2.0 μm on one side of the separator substrate. This functional layer-equipped separator was used as the evaluation separator. The evaluation separator was cut into two 10 mm x 50 mm strips. The two cut evaluation separators were stacked with the functional layers facing each other to obtain a pre-press test specimen. This pre-press test specimen was placed in a laminate packaging material and hot-pressed together with the packaging material at 40°C and a load of 6.0 MPa using a flat press for 5 minutes. The pressed test specimen was removed from the packaging material, and cellophane tape was attached to one side of the test specimen. The cellophane tape used was specified in JIS Z1522. The cellophane tape was fixed to a horizontal test table. One end of the separator was pulled vertically upward at a pulling rate of 50 mm / min to measure the stress when peeled off. Similar measurements were performed three times, and the average of the measured values ​​was calculated as the peel strength P1 (N / m) and evaluated according to the following criteria. A smaller peel strength P1 indicates better blocking resistance.A: The separator fell off before the peel strength test. B: The peel strength P1 was less than 0.2 N / m. C: The peel strength P1 was 0.2 N / m or more but less than 0.5 N / m. D: The peel strength P1 was 0.5 N / m or more. <Room Temperature Adhesion> A polyethylene microporous film (thickness: 12 μm) was prepared as a separator substrate. The functional layer compositions prepared in the Examples and Comparative Examples were applied to one side of this separator substrate using a bar coater. The separator substrate coated with the functional layer composition was then dried at 50°C for 10 minutes to produce a separator (laminate) with a functional layer comprising a 2.0 μm-thick functional layer on one side of the separator substrate. This separator with this functional layer was used as the separator for evaluation. The separator for evaluation was cut into a 10 mm x 50 mm strip. The surface of the negative electrode (negative electrode composite layer side) prepared in each of the examples and comparative examples was aligned with the surface of the functional layer of the cut-out separator for evaluation to obtain a pre-press test specimen. This pre-press test specimen was placed in a laminate packaging material, and the packaging material was hot-pressed for 1 minute using a flat press at a temperature of 25°C and a load of 1.0 MPa. The pressed test specimen was removed from the packaging material, and cellophane tape was attached to the surface of the negative electrode current collector side with the surface facing downward. Cellophane tape specified in JIS Z1522 was used. The cellophane tape was fixed to a horizontal test table. One end of the separator was then pulled vertically upward at a tensile speed of 50 mm / min, and the stress when peeled was measured. Similar measurements were performed three times, and the average of the measured values ​​was calculated as the peel strength P2 and evaluated according to the following criteria. A higher peel strength P2 indicates better room-temperature adhesion. A: Peel strength P2 is 2.0 N / m or more. B: Peel strength P2 is 0.5 N / m or more but less than 2.0 N / m. C: Peel strength P2 is less than 0.5 N / m. D: The separator falls off before the peel strength test. <Internal Resistance> After injecting the electrolyte, the lithium ion secondary batteries prepared in the Examples and Comparative Examples were left to stand at a temperature of 25°C for 5 hours. Next, they were charged to a cell voltage of 3.65 V using a constant current method at 25°C and 0.2 C (C is a value expressed as rated capacity (mA) / 1 h (hours)), and then aged for 12 hours at a temperature of 60°C. Then, they were discharged to a cell voltage of 3.00 V using a constant current method at 25°C and 0.2 C.Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed using a 0.2C constant current method, and CC discharging was performed to 3.00V using a 0.2C constant current method. This charge and discharge at 0.2C was repeated three times. Thereafter, in a 25°C atmosphere, after charging to 50% of SOC (State Of Charge, charge depth) at 1C, 15-second charge and 15-second discharge were performed at 0.5C, 1.0C, 1.5C, and 2.0C, centered on 50% SOC, and in each case (charge side and discharge side), the battery voltage after 0.1 seconds was plotted against the current value, and the slope was determined as IV resistance (Ω) (IV resistance during charge and IV resistance during discharge). The obtained IV resistance value (Ω) was evaluated according to the following criteria. The smaller the IV resistance value, the lower the internal resistance and the lower the DC resistance. A: IV resistance is 5Ω or less. B: IV resistance is more than 5Ω and less than 6Ω. C: IV resistance is more than 6Ω and less than 7.5Ω. D: IV resistance is more than 7.5Ω.

[0128] Example 1 Preparation of Aqueous Dispersion Containing Particulate Polymer A Preparation of Monomer Composition 20.6 parts of styrene as an aromatic vinyl monomer, 0.5 parts of ethylene glycol dimethacrylate and 10.0 parts of glycidyl methacrylate as crosslinkable monomers, and 58.9 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer were mixed to prepare a monomer composition. Preparation of Colloidal Dispersion A colloidal dispersion containing magnesium hydroxide as a metal hydroxide was prepared by gradually adding, with stirring, an aqueous solution obtained by dissolving 7.0 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution obtained by dissolving 10.0 parts of magnesium chloride in 200 parts of ion-exchanged water. Formation of Core Portions Particulate polymer A was prepared by suspension polymerization. Specifically, the above-described monomer composition was added to the colloidal dispersion containing magnesium hydroxide, followed by further stirring. Then, 2.0 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, product name "Perbutyl O") as a polymerization initiator was added to obtain a mixed solution. The resulting mixed solution was subjected to high-shear stirring at 12,000 rpm for 1 minute using an in-line emulsifying disperser (manufactured by Pacific Machinery Works, product name "Cavitron") to form droplets of the monomer composition in the colloidal dispersion containing magnesium hydroxide. The colloidal dispersion containing the above-described monomer composition droplets was placed in a reactor, heated to 90°C, and subjected to a polymerization reaction for 5 hours to obtain an aqueous dispersion containing particulate polymers constituting the core portion. [Shell Formation] 0.5 parts of hydroxypropyl methylcellulose was dissolved in 420 parts of ion-exchanged water at room temperature to prepare an aqueous hydroxypropyl methylcellulose solution. The aqueous dispersion containing the particulate polymer constituting the core portion obtained by the suspension polymerization was centrifuged (10,000 rpm, 10 minutes, 25°C) to recover a wet cake of the precipitated polymer. An amount of the wet cake so obtained that the solid content was 15.5 parts was added to the aqueous hydroxypropyl methylcellulose solution and redispersed by stirring at room temperature for 30 minutes.To the redispersed dispersion, 0.15 parts of 2,2'-azobis(2-methylpropionamide) dihydrochloride as a polymerization initiator and 1.72 parts of styrene as an aromatic vinyl monomer were added (wet cake / styrene (mass ratio) = 90 / 10), and the temperature was raised to 70°C to carry out a polymerization reaction for 6 hours, thereby obtaining an aqueous dispersion containing particulate polymer A having a core-shell structure. Using this aqueous dispersion containing particulate polymer A, the volume average particle size, glass transition temperature, storage modulus, electrolyte swelling degree, THF elution amount, and number average molecular weight of the THF eluate component were measured. The results are shown in Table 1. <Preparation of Aqueous Dispersion Containing Particulate Polymer B> 70 parts of ion-exchanged water, 0.15 parts of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") as an emulsifier, and 0.5 parts of ammonium persulfate as a polymerization initiator were supplied to a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 60°C. Meanwhile, in a separate vessel, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 94 parts of n-butyl acrylate as a (meth)acrylic acid ester monomer, 2 parts of methacrylic acid as an acid group-containing monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, and 1 part of allyl methacrylate and 1 part of allyl glycidyl ether as crosslinkable monomers were mixed to prepare a monomer composition. The obtained monomer composition was continuously added to the above-mentioned reactor equipped with a stirrer over 4 hours to carry out polymerization. During the addition, the reaction was carried out at 60°C. After the addition was completed, the mixture was stirred at 70°C for a further 3 hours, and then the reaction was terminated, thereby obtaining an aqueous dispersion containing particulate polymer B. The obtained particulate polymer B had a volume average particle diameter of 0.25 μm and a glass transition temperature of −40°C. <Preparation of Functional Layer Composition> 0.5 parts of sodium polyacrylate as a dispersant was added to 70 parts of alumina (manufactured by Sumitomo Chemical Co., Ltd., product name “AKP3000”, volume average particle diameter: 0.7 μm) as heat-resistant particles, and ion-exchanged water was added so that the solid concentration was 55%, and the mixture was mixed using a ball mill to obtain a pre-mixing slurry.Furthermore, 20 parts (solids equivalent) of an aqueous dispersion containing particulate polymer A, 5 parts (solids equivalent) of an aqueous dispersion containing particulate polymer B, 1.5 parts of carboxymethyl cellulose as a thickener, and 0.2 parts of sodium dodecylbenzenesulfonate ("Neopelex G-15" manufactured by Kao Chemical Corporation) as a dispersion stabilizer were mixed, and the resulting mixture (particulate polymer A / particulate polymer B (mass ratio) = 80 / 20) was added to the pre-mixing slurry. Further, ion-exchanged water was added to the mixture to a solids concentration of 40%, and the pH was adjusted to 7.0 using a 3% aqueous sodium hydroxide solution to obtain a functional layer composition. Using this functional layer composition, a separator (laminate) with a functional layer on one side of a separator substrate was produced, and its blocking resistance and room temperature adhesion were evaluated. The results are shown in Table 1. <Preparation of a separator (laminate) with a functional layer> A polyethylene microporous membrane (thickness: 12 μm) was prepared as a separator substrate. The functional layer composition obtained as described above was applied to one side of this separator substrate using a bar coater method. Next, the separator substrate coated with the functional layer composition was dried at 50°C for 10 minutes to form a functional layer. The same operation was performed on the other side of the separator substrate, producing a separator (laminate) with a functional layer having a functional layer of 2.0 μm thickness on each side of the separator substrate. <Preparation of a positive electrode> LiCoO as a positive electrode active material. ２100 parts of acetylene black (volume average particle diameter: 12 μm), 2 parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., "HS-100") as a conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Corporation, "#7208") as a binder for the positive electrode composite layer in terms of solids content, and N-methylpyrrolidone as a solvent were mixed to a total solids concentration of 70%. These were mixed using a planetary mixer to prepare a positive electrode slurry composition. The positive electrode slurry composition was applied using a comma coater to a 20 μm thick aluminum foil current collector so that the film thickness after drying was approximately 150 μm, and then dried. This drying was performed by conveying the aluminum foil at a speed of 0.5 m / min in an oven at 60 ° C for 2 minutes. Thereafter, the aluminum foil was heat-treated at 120 ° C for 2 minutes to obtain a pre-press positive electrode blank. This pre-pressed positive electrode blank was rolled with a roll press to obtain a positive electrode having a positive electrode composite layer (thickness: 60 μm). <Preparation of Negative Electrode> 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were placed in a 5 MPa pressure vessel equipped with a stirrer, thoroughly stirred, and then heated to 50 ° C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling, and a mixture containing a binder (SBR) for the negative electrode composite layer was obtained. A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode composite layer, and the pH was adjusted to 8. Unreacted monomers were removed by heated vacuum distillation. The mixture was then cooled to 30 ° C or below to obtain an aqueous dispersion containing the desired binder for the negative electrode composite layer. 80 parts of artificial graphite (volume average particle diameter: 15.6 μm) as the negative electrode active material (1), 16 parts of silicon-based active material SiOx (volume average particle diameter: 4.9 μm) as the negative electrode active material (2) were blended, and 2.5 parts of a 2% aqueous solution of carboxymethylcellulose sodium salt (manufactured by Nippon Paper Industries Co., Ltd., "MAC350HC") as a viscosity modifier, equivalent to solids, and ion-exchanged water were mixed to adjust the solids concentration to 68%, and then further mixed at 25 ° C. for 60 minutes. The solids concentration was further adjusted to 62% with ion-exchanged water, and then further mixed at 25 ° C. for 15 minutes to obtain a mixed solution.To this mixture, 1.5 parts of the aqueous dispersion containing the binder for the negative electrode composite layer (solids equivalent) and ion-exchanged water were added, adjusting the final solids concentration to 52%, and further mixing was performed for 10 minutes to obtain a mixed solution. This mixture was degassed under reduced pressure to obtain a negative electrode slurry composition with good fluidity. The negative electrode slurry composition was applied to a 20 μm-thick copper foil current collector using a comma coater so that the dried film thickness was approximately 150 μm, and then dried. This drying was performed by conveying the copper foil at a speed of 0.5 m / min in an oven at 60°C for 2 minutes. The resulting mixture was then heated at 120°C for 2 minutes to obtain a pre-pressed negative electrode blank. This pre-pressed negative electrode blank was rolled using a roll press to obtain a negative electrode having a negative electrode composite layer (thickness: 80 μm). <Preparation of Lithium-Ion Secondary Battery> An aluminum packaging material was prepared as the battery exterior. The positive electrode obtained above was cut into a 4 x 4 cm square and placed so that the surface on the current collector side was in contact with the aluminum packaging exterior. The separator with functional layer obtained above was then cut into a 4.4 x 4.4 cm square and placed on the surface of the positive electrode composite layer of the positive electrode, with the functional layer of the separator facing the positive electrode. Furthermore, the negative electrode obtained above was cut into a 4.2 x 4.2 cm square and placed on the separator so that the surface on the negative electrode composite layer side faced the separator. The resultant was then wound using a winding machine to obtain a wound body. This wound body was pressed at 50°C and 1 MPa to form a flat body, which was then wrapped in an aluminum packaging exterior as the exterior of the battery, and an electrolyte solution [solvent: a mixed solvent of ethylene carbonate / ethyl methyl carbonate (weight ratio) = 3 / 7, additive: containing 2 vol% vinylene carbonate (solvent ratio), supporting electrolyte: LiPF6 with a concentration of 1 mol / L] was added. ６ )] was injected into the battery so that no air remained. The opening of the aluminum packaging was then heat-sealed at a temperature of 150°C to close the opening, thereby preparing a lithium-ion secondary battery. The internal resistance of this lithium-ion secondary battery was evaluated. The results are shown in Table 1.

[0129] (Example 2) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing particulate polymer A, the amount of magnesium chloride was changed from 10.0 parts to 5.9 parts and the amount of sodium hydroxide was changed from 7.0 parts to 4.1 parts. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0130] (Example 3) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing particulate polymer A, the amount of magnesium chloride was changed from 10.0 parts to 6.5 parts and the amount of sodium hydroxide was changed from 7.0 parts to 4.6 parts. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0131] (Example 4) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing particulate polymer A, the amount of magnesium chloride was changed from 10.0 parts to 8.5 parts and the amount of sodium hydroxide was changed from 7.0 parts to 6.0 parts. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0132] (Example 5) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing particulate polymer A, the amount of magnesium chloride was changed from 10.0 parts to 11.0 parts and the amount of sodium hydroxide was changed from 7.0 parts to 7.7 parts. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0133] (Example 6) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing particulate polymer A, a 15% aqueous solution of sodium dodecylbenzenesulfonate was used instead of a colloidal dispersion containing magnesium hydroxide as a metal hydroxide. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0134] (Examples 7 to 12 and 14 to 21) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that the amount of each monomer added in preparing the aqueous dispersion containing particulate polymer A was changed as shown in Tables 1 and 2. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0135] (Example 13) An aqueous dispersion containing a particulate polymer A, an aqueous dispersion containing a particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that, in preparing the aqueous dispersion containing a particulate polymer A, the amount of each monomer added was changed as shown in Table 2 and 1 part of tert-dodecyl mercaptan was used as a chain transfer agent. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0136] Example 22 An aqueous dispersion containing particulate polymer B, a composition for a functional layer, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that an aqueous dispersion containing particulate polymer A prepared as follows was used. Evaluations were then performed in the same manner as in Example 1. The results are shown in Table 3. <Preparation of aqueous dispersion containing particulate polymer A> A monomer composition was prepared by mixing 41 parts of styrene as an aromatic vinyl monomer, 1.2 parts of ethylene glycol dimethacrylate and 10 parts of glycidyl methacrylate as crosslinkable monomers, and 47.8 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer. The above-mentioned monomer composition was added to an aqueous solution containing 6.2 parts in terms of solids of polyvinyl alcohol having a degree of polymerization of 3000 to 4000, and after further stirring, 2.0 parts of t-butylperoxy-2-ethylhexanoate (NOF Corporation, "Perbutyl O") as a polymerization initiator was added to obtain a mixed solution. The obtained mixed solution was subjected to high-shear stirring at a rotation speed of 12,000 rpm for 1 minute using an in-line emulsifying disperser (Pacific Machinery Works, "Cavitron") to form droplets of the monomer composition. The mixed solution in which the droplets of the monomer composition had been formed was placed in a reactor, heated to 90°C, and subjected to a polymerization reaction for 5 hours to obtain an aqueous dispersion containing particulate polymer A, which is a single polymer particle.

[0137] Examples 23 to 25 An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 22, except that the amount of each monomer added in preparing the aqueous dispersion containing particulate polymer A was changed as shown in Table 3. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0138] (Example 26) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 24, except that the amount of polyvinyl alcohol was changed from 6.2 parts to 7.8 parts when preparing the aqueous dispersion containing particulate polymer A. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0139] (Example 27) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 24, except that the amount of polyvinyl alcohol was changed from 6.2 parts to 5.1 parts when preparing the aqueous dispersion containing particulate polymer A. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0140] (Example 28) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 24, except that the amount of polyvinyl alcohol was changed from 6.2 parts to 2.4 parts when preparing the aqueous dispersion containing particulate polymer A. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0141] (Comparative Examples 1 and 2) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that the amount of each monomer added in preparing the aqueous dispersion containing particulate polymer A was changed as shown in Table 4. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0142] Comparative Example 3 An aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that an aqueous dispersion containing particulate polymer A prepared as follows was used. Evaluations were then performed in the same manner as in Example 1. The results are shown in Table 4. <Preparation of Aqueous Dispersion Containing Particulate Polymer A> 20.6 parts of styrene as an aromatic vinyl monomer, 0.5 parts of ethylene glycol dimethacrylate and 10 parts of glycidyl methacrylate as crosslinkable monomers, 58.9 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, 0.03 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were placed in a flask and thoroughly stirred. The mixture was then heated to 60°C to initiate polymerization. The polymerization was continued until the polymerization conversion rate reached 96%, thereby obtaining an aqueous dispersion containing a particulate polymer constituting the core portion. Next, this aqueous dispersion was heated to 70°C, and then 10 parts of styrene for forming the shell portion was continuously added over 30 minutes, and the polymerization was continued. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling, thereby obtaining an aqueous dispersion containing a particulate polymer A having a core-shell structure.

[0143] (Comparative Example 4) An aqueous dispersion containing particulate polymer A, an aqueous dispersion containing particulate polymer B, a functional layer composition, a separator with a functional layer, a positive electrode, a negative electrode, and a lithium ion secondary battery were prepared or fabricated in the same manner as in Example 1, except that the amount of magnesium chloride was changed from 10.0 parts to 3.9 parts and the amount of sodium hydroxide was changed from 7.0 parts to 2.7 parts when preparing an aqueous dispersion containing particulate polymer A. Then, evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0144] In Tables 1 to 4 shown below, "ST" represents styrene, "EDMA" represents ethylene glycol dimethacrylate, "GMA" represents glycidyl methacrylate, "2EHA" represents 2-ethylhexyl acrylate, "BA" represents n-butyl acrylate, and "TDM" represents tert-dodecyl mercaptan.

[0145]

[0146]

[0147]

[0148]

[0149] Tables 1 to 4 show that in Examples 1 to 28, which used functional layer compositions containing particulate polymer A whose volume average particle size and THF elution amount were within the specified ranges and whose storage modulus at 25°C was equal to or less than a specified value, functional layers with high room-temperature adhesion were obtained, and the internal resistance of electrochemical devices including such functional layers was reduced. On the other hand, in Comparative Example 1, which used a functional layer composition containing particulate polymer A whose THF elution amount was outside the specified range, and Comparative Example 4, which used a functional layer composition containing particulate polymer A whose volume average particle size was outside the specified range, the internal resistance of the electrochemical device was increased compared to Examples 1 to 28. Furthermore, in Comparative Example 2, which used a functional layer composition containing particulate polymer A whose storage modulus exceeded the specified value, the room-temperature adhesion of the functional layer was reduced compared to Examples 1 to 28. Furthermore, in Comparative Example 3, which used a functional layer composition containing particulate polymer A whose volume average particle size was outside the specified range, the room-temperature adhesion of the functional layer was reduced and the internal resistance of the electrochemical device was increased compared to Examples 1 to 28.

[0150] According to the present invention, it is possible to provide a composition for an electrochemical device functional layer that is capable of forming an electrochemical device functional layer that has excellent room temperature adhesion and can reduce the internal resistance of the electrochemical device. Further, according to the present invention, it is possible to provide a laminate for an electrochemical device that can reduce the internal resistance of the electrochemical device. And according to the present invention, it is possible to provide an electrochemical device with low internal resistance.

Claims

1. A composition for an electrochemical element functional layer comprising a particulate polymer A, wherein the particulate polymer A has a volume average particle diameter of 0.75 μm or more and 17.5 μm or less, the amount of the particulate polymer A that dissolves into tetrahydrofuran is 0.05 mass % or more and 60 mass % or less, and the particulate polymer A has a storage modulus at 25° C. of 35 MPa or less.

2. The composition for an electrochemical device functional layer according to claim 1, wherein the number average molecular weight of the tetrahydrofuran eluted component of the particulate polymer A is 500 or more and 500,000 or less.

3. The composition for an electrochemical device functional layer according to claim 1, wherein the particulate polymer A has a glass transition temperature of -50°C or higher and 95°C or lower.

4. The composition for an electrochemical device functional layer according to claim 1, wherein the particulate polymer A has a degree of swelling in an electrolyte of 100% or more and 500% or less.

5. The composition for an electrochemical device functional layer according to claim 1, further comprising a dispersion medium containing water and having a pH of 3.0 or more and 12.0 or less.

6. The composition for electrochemical element functional layers according to claim 1, further comprising a particulate polymer B different from the particulate polymer A and a dispersant, wherein the mass ratio of the particulate polymer A to the particulate polymer B (particulate polymer A / particulate polymer B) is 1 / 99 or more and 99 / 1 or less.

7. The composition for an electrochemical element functional layer according to claim 1, wherein the particulate polymer A contains aromatic vinyl monomer units in a proportion of 10 mass % or more.

8. The composition for an electrochemical element functional layer according to claim 1, wherein the particulate polymer A contains a crosslinkable monomer unit in a proportion of 0.01% by mass or more and 50% by mass or less.

9. The composition for an electrochemical device functional layer according to claim 1, wherein the particulate polymer A has a core-shell structure.

10. The composition for electrochemical element functional layers according to claim 9, wherein the mass ratio of the core portion to the shell portion of the core-shell structure (core portion / shell portion) is 0.1 / 99.9 or more and 99.9 / 0.1 or less.

11. The composition for an electrochemical device functional layer according to claim 1, further comprising non-conductive heat-resistant particles.

12. A laminate for an electrochemical device, comprising a substrate and a functional layer for an electrochemical device formed on the substrate, the functional layer for an electrochemical device being formed using a composition for an electrochemical device functional layer according to any one of claims 1 to 11.

13. An electrochemical device comprising the laminate for electrochemical devices according to claim 12.

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