Separator binder composition, separator binder, separator and battery

Abstract

The invention provides a diaphragm binder composition, a diaphragm binder, a diaphragm and a battery. The diaphragm binder composition comprises a granular polymer A and a granular polymer B, the glass transition temperature of the granular polymer A is not higher than 30 DEG C; the D50 particle size of the granular polymer B is larger than the D90 particle size of the granular polymer A; wherein the granular polymer B is a polyvinylidene fluoride polymer or a fluorine-free polymer, and when the granular polymer B is the fluorine-free polymer, the glass transition temperature of the granular polymer B is not lower than 50 DEG C. The diaphragm obtained by using the diaphragm binder composition can realize better bonding force by pressurizing at normal temperature, has a room-temperature bonding function, can reduce energy consumption and save cost, and the diaphragm bonded at room temperature does not generate self-adhesion after being rolled. The binder used by the diaphragm is not easy to form a film at high temperature, and the battery prepared by adopting the diaphragm has excellent high-temperature cycle performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to a separator adhesive composition, a separator adhesive, a separator and a battery. BACKGROUND

[0002] Lithium ion battery is a kind of rechargeable battery with broad application prospect, which has been applied in the fields of electric bicycles, electric vehicles, energy storage and various portable devices from mobile phones, notebook computers and other fields, and is an ideal mobile power supply.

[0003] The lithium ion battery is generally composed of a positive electrode, a negative electrode, a separator, an electrolyte and a battery shell. The separator is one of the key inner components, which separates the positive and negative electrodes of the battery to prevent the positive and negative electrodes from contacting and short-circuiting. At present, the separator used in the lithium ion battery is generally a polyolefin porous membrane. Since the melting point of the polyolefin porous membrane is relatively low, when the temperature of the battery rises due to internal or external factors, the polyolefin porous membrane will shrink or melt, thereby causing the positive and negative electrodes to directly contact, leading to battery short circuit, and further causing accidents such as battery combustion and explosion. In order to solve these problems, inorganic particles are usually coated on the surface of the separator substrate by using a polymer adhesive to make a composite separator, such as coating ceramic particles on the surface of the separator substrate to make a ceramic / polymer composite separator, hoping to reduce the thermal shrinkage of the separator by using the heat resistance of the ceramic particles. At the same time, an additional separator adhesive, such as polyvinylidene fluoride (PVDF), is coated on the surface of the ceramic coating for bonding the separator and the positive and negative electrode sheets, playing a role in fixing the structure of the battery.

[0004] At present, the adhesive used for bonding the separator and the electrode sheet, such as PVDF or ordinary polyacrylate emulsion, has many problems. In order to achieve effective bonding, the ordinary polyacrylate adhesive usually needs to be combined with a hot pressing process, which has high energy consumption and complex process. In order to achieve room temperature bonding, a lower glass transition temperature (Tg) is required, but this will cause the adhesive to be sticky and the separator to be seriously self-bonded during winding; if the Tg is increased to prevent self-bonding, the room temperature bonding ability will be lost. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a separator adhesive composition, a separator adhesive, a separator and a battery.

[0006] The present application achieves the technical effects by the following technical solutions:

[0007] In a first aspect, the present application provides a separator adhesive composition, which comprises a granular polymer A and a granular polymer B; the glass transition temperature of the polymer A is not higher than 30℃; the D50 particle size of the granular polymer B is greater than the D50 particle size of the granular polymer A. 50 90 The D50 particle size of the granular polymer B is greater than the D50 particle size of the granular polymer A.​

[0008] wherein the particulate polymer B is a polyvinylidene fluoride-based polymer or a non-fluorine-containing polymer, and when the particulate polymer B is a non-fluorine-containing polymer, the particulate polymer B has a glass transition temperature of not less than 50°C.

[0009] Further, the mass ratio of the particulate polymer A to the particulate polymer B is (0.1-5): 1, based on the total solid mass of the composition. Specifically, the mass ratio of the particulate polymer A to the particulate polymer B can be 0.1:1, 0.3:1, 1:1, 2:1, 4:1, 5:1.

[0010] Further, the particulate polymer A has a glass transition temperature of -60°C to 30°C. Specifically, the particulate polymer A can have a glass transition temperature of -60°C, -55°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, 25°C, 30°C.

[0011] Further, the particulate polymer A comprises a core polymer and a shell polymer disposed on the surface of the core polymer, and the mass ratio of the core polymer to the shell polymer is (1-4):(4-1). Specifically, the mass ratio of the core polymer to the shell polymer can be 1:4, 1:3, 1:2, 1:1, 3:1, 2:1, 4:1.

[0012] Further, the core polymer has a glass transition temperature of 40°C to 110°C, and the shell polymer has a glass transition temperature of -60°C to 30°C. Specifically, the core polymer can have a glass transition temperature of 40°C, 45°C, 60°C, 70°C, 80°C, 90°C, 108°C, 110°C, and the shell polymer can have a glass transition temperature of -60°C, -55°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, 25°C, 30°C. The core polymer is more preferably 60°C to 110°C, and the higher the core polymer Tg, the more advantageous it is to prevent the particles from being transformed into films. When the core polymer Tg is above 60°C, the particle morphology hardly changes during the coating and baking process. When the shell polymer is higher than 30°C, it is difficult to produce good room temperature adhesion.

[0013] The purpose of increasing the high Tg core polymer is mainly to prevent the separator binder from being transformed into films during the coating and baking process. When the core particulate polymer A does not contain a high Tg core but only contains a low Tg shell, the separator binder is prone to be transformed into films during the coating and baking process, thereby causing the separator pores to be blocked, hindering the transmission of lithium ions, and leading to an increase in battery impedance. When the proportion of the core polymer is too small, it is difficult to produce the effect of preventing the transformation into films, and when the proportion of the core polymer is too large, the low Tg component is too small, which can lead to insufficient room temperature adhesion.

[0014] Further, the D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer A is 0.4-6 μm. 90 The ratio D2 / D3 of the D50 of the particulate polymer B to the D50 of the particulate polymer A is (1.1-40): 1. 50 The D50 of the particulate polymer A is 0.4-6 μm. 90 The ratio D2 / D3 of the D50 of the particulate polymer B to the D50 of the particulate polymer A can be 1.1:1, 1.5:1, 2:1, 3:1, 5:1, 7:1, 8:1, 9:1, 10:1, 14:1, 16:1, 19:1, 20:1, 40:1. The D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 90 This means that more than half of the particulate polymer B has a particle size greater than the particle size of the majority of the particulate polymer A, and can avoid direct contact between the particulate polymer A and the adjacent separator, and can prevent self-sticking of the separator during winding.

[0015] Further, the D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer A is 0.4-6 μm. 50 The ratio D2 / D1 of the D50 of the particulate polymer B to the D50 of the particulate polymer A is (2-25): 1. 50 The D50 of the particulate polymer A is 0.4-6 μm. 50 The ratio D2 / D1 of the D50 of the particulate polymer B to the D50 of the particulate polymer A can be 2:1, 2.5:1, 3.3:1, 5:1, 7:1, 8.75:1, 9.5:1, 10:1, 15:1, 17.5:1, 20:1, 22:1, 25:1. The D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer B is also required to be greater than the D50 of the particulate polymer A. 50 Since the low Tg portion of the particulate polymer A functions as a room temperature adhesive, sufficient contact between the particulate polymer A and the pole piece is required to produce an adhesive effect after the separator and the pole piece are pressed, and therefore if the D50 of the particulate polymer B is too large, the particulate polymer A will have difficulty contacting the pole piece after the pressing process, resulting in insufficient adhesive force. 50 The D50 of the particulate polymer B is greater than the D50 of the particulate polymer A.

[0016] Further, the D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer A is 0.4-6 μm.

[0017] Further, the D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 50 The D50 of the particulate polymer B is 1-20 μm.

[0018] Further, the D50 of the particulate polymer B is greater than the D50 of the particulate polymer A. 90 The D50 of the particulate polymer A is 0.5-15 μm.

[0019] Specifically, the D of the particulate polymer A is 0.4-10 μm. 50 The particle size D1 can be 0.4 μm, 0.6 μm, 0.65 μm, 0.8 μm, 1 μm, 1.1 μm, 6 μm; the D of the particulate polymer B is 1-20 μm. 50 The particle size D2 can be 1 μm, 1.5 μm, 5 μm, 7 μm, 8 μm, 9.5 μm, 20 μm; the D of the particulate polymer A is 0.4-10 μm. 90 The particle size D3 can be 0.5 μm, 0.7 μm, 0.8 μm, 1 μm, 1.3 μm, 1.4 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 15 μm.

[0020] Further, the glass transition temperature of the particulate polymer B is 50-110 ℃; specifically, the glass transition temperature of the particulate polymer B can be 50 ℃, 55 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 108 ℃, 110 ℃. If the glass transition temperature of the particulate polymer B is too low, self-sticking at low temperature is prone to occur, and the effect of preventing self-sticking of the separator cannot be achieved. If the glass transition temperature of the particulate polymer B is too high, on the one hand, the particulate polymer B is difficult to be pressed flat enough to make the particulate polymer A contact and bond with the pole piece, and on the other hand, the high-temperature bonding force is poor due to the too high glass transition temperature of the particulate polymer B.

[0021] Further, the core polymer and the shell polymer each comprise one or more of a benzene ring structural unit, a cyano structural unit, and an ester group structural unit.

[0022] Further, the particulate polymer B comprises one or more of a benzene ring structural unit, a cyano structural unit, an ester group structural unit, and a vinylidene fluoride structural unit.

[0023] In a second aspect, the present application provides a separator adhesive comprising the separator adhesive composition as described above.

[0024] In a third aspect, the present application provides a separator comprising a substrate and a bonding layer, wherein the bonding layer uses the separator adhesive composition as described above.

[0025] In a fourth aspect, the present application provides a battery comprising the separator as described above.

[0026] Compared with the prior art, the present application has the following beneficial effects: the separator adhesive composition provided by the present application comprises a particulate polymer A and a particulate polymer B, the D of the particulate polymer B is greater than the D of the particulate polymer A, and the glass transition temperature of the particulate polymer B is 50-110 ℃. 50 The particle size D is greater than the D of the particulate polymer A 90The particle size of the granular polymer A is not more than 30℃, the glass transition temperature of the polymer B is polyvinylidene fluoride polymer or non-fluorine polymer, and the glass transition temperature of the granular polymer B is not less than 50℃ when the granular polymer B is non-fluorine polymer. The technical problem of the contradiction between the room temperature adhesion and the anti-self-adhesion of the adhesive is fundamentally solved by the physical blending of the granular polymer A and the granular polymer B and the Tg and particle size parameters, and the industrial production and popularization are easy. The separator using the adhesive composition has good adhesion at room temperature, no self-adhesion during winding, and excellent high-temperature cycle performance. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with specific embodiments. It should be understood that the embodiments described herein are part of the embodiments of the present application, rather than all the embodiments, and are used to explain the present application, but not to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0028] In a first aspect, the present application provides a separator adhesive composition, comprising a granular polymer A and a granular polymer B; the glass transition temperature of the granular polymer A is not more than 30℃; the D 50 The particle size of the granular polymer B is greater than the D 90 The particle size of the granular polymer A; wherein the polymer B is polyvinylidene fluoride polymer or non-fluorine polymer, and the glass transition temperature of the granular polymer B is not less than 50℃ when the polymer B is non-fluorine polymer. It can be understood that the granular polymer B can be primary particles or secondary particles formed by agglomeration of small particle size polymers, and when the granular polymer B is secondary particles formed by agglomeration of small particle size polymers, the particle size D2 is the particle size of the secondary particles. The separator adhesive composition provided by the present application physically blends the granular polymer A and the granular polymer B, and the D 50 The particle size of the granular polymer B is greater than the D 90 The particle size of the granular polymer A is not more than 30℃, the glass transition temperature of the polymer B is polyvinylidene fluoride polymer or non-fluorine polymer, and the glass transition temperature of the granular polymer B is not less than 50℃ when the granular polymer B is non-fluorine polymer. The technical problem of the contradiction between the room temperature adhesion and the anti-self-adhesion of the adhesive is fundamentally solved by the physical blending of the granular polymer A and the granular polymer B and the Tg and particle size parameters, and the industrial production and popularization are easy. The separator using the adhesive composition has good adhesion at room temperature, no self-adhesion during winding, and excellent high-temperature cycle performance.

[0029] Specifically, the larger granular polymer B acts as a "spacer" to prevent the granular polymer A in the same film layer and adjacent film layers from contacting each other during winding, thereby avoiding self-adhesion. The smaller granular polymer A has a lower glass transition temperature, so that it has adhesion at room temperature; the granular polymer B remains to meet the non-adhesion at room temperature, which can be achieved by having a higher glass transition temperature or being partially crystallized at room temperature, further strengthening the anti-adhesion effect, and keeping the shape stable at high temperature environment of the battery and not easily blocking the hole.

[0030] In some specific embodiments, the mass ratio of the granular polymer A to the granular polymer B is (0.1-5):1.

[0031] In some specific embodiments, the glass transition temperature of the granular polymer A is -60℃~30℃.

[0032] In some specific embodiments, the granular polymer A comprises a core polymer and a shell polymer arranged on the surface of the core polymer, the mass ratio of the core polymer to the shell polymer is (1~4):(4~1); and / or, the glass transition temperature of the core polymer is 40℃~110℃; the glass transition temperature of the shell polymer is -60℃~30℃. The granular polymer A has a core-shell structure, wherein the glass transition temperature of the core polymer is 40~110℃, and the glass transition temperature of the shell polymer is -60℃~30℃. The granular polymer A has a core-shell structure, by designing a high-Tg core and a low-Tg shell, the comprehensive performance thereof can be further optimized, so that it has room temperature adhesion while the inner core does not melt, ensuring the performance of the battery.

[0033] In some specific embodiments, the D 50 particle size D2 of the granular polymer B is (1.1~40):1 relative to the D 90 particle size D1 of the granular polymer A.

[0034] and / or, the D 50 particle size D2 of the granular polymer B is (2~25):1 relative to the D 50 particle size D1 of the granular polymer A.

[0035] and / or, the D 50 particle size D1 of the granular polymer A is 0.4~6μm.

[0036] and / or, the D 50 particle size D2 of the granular polymer B is 1~20μm.

[0037] and / or, the D 90 particle size D3 of the granular polymer A is 0.5~15μm.

[0038] In some specific embodiments, the glass transition temperature of the particulate polymer B is 50-110°C. The particulate polymer B has no adhesion at room temperature, which prevents the separators from adhering to each other. When the separators are hot-pressed, the particulate polymer B can also provide hot-press adhesion.

[0039] In some specific embodiments, the core polymer and the shell polymer each contain one or more of benzene ring structural units, cyano structural units, and ester group structural units.

[0040] In some specific embodiments, the particulate polymer B contains one or more of benzene ring structural units, cyano structural units, ester group structural units, and vinylidene fluoride structural units. The benzene ring structure has relatively low polarity and has good affinity with graphite sheets and the like, which is conducive to the adhesion of the negative electrode sheets. The cyano group, the ester group, and fluorine have relatively high polarity and have good affinity with the positive electrode main material and ceramics and the like, which is conducive to the adhesion with the ceramic layer and the positive electrode sheets.

[0041] In particular, the core polymer and the shell polymer can each be formed by polymerization of at least one of a styrene-based monomer, an acrylate-based monomer, a methacrylate-based monomer, an acrylonitrile-based monomer, including but not limited to styrene, a-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylstyrene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, vinyl naphthalene, p-t-butylstyrene, methyl acrylate, acrylonitriles, methacrylonitrile, 2-cyanoethyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, dicyclopentenyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, carboxyethyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, phenoxyethyl methacrylate, dicyclopentenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, polyethylene glycol mono[(meth)acrylate], glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, ethoxylated ethylene glycol diacrylate, ethoxylated ethylene glycol dimethacrylate, allyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, aminoethyl acrylate, aminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, t-butylaminoethyl methacrylate. Preferably, the core polymer and / or the shell polymer include one or more of an acrylate-based copolymer, a methacrylate-based copolymer, a styrene-acrylate copolymer, a butadiene-styrene copolymer, a hydrogenated butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, a hydrogenated butadiene-acrylonitrile copolymer.

[0042] The particulate polymer B can be polymerized from at least one raw material including vinylidene fluoride, styrene-based monomers, acrylate-based monomers, methacrylate-based monomers, acrylonitrile-based monomers, including but not limited to styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylstyrene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, vinyl naphthalene, p-t-butylstyrene, methyl acrylate, acrylonitrile-based, methacrylonitrile, 2-cyanoethyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, dicyclopentenyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, carboxyethyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, phenoxyethyl methacrylate, dicyclopentenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, polyethylene glycol mono[(meth)acrylate], glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, ethoxylated ethylene glycol diacrylate, ethoxylated ethylene glycol dimethacrylate, allyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, aminoethyl acrylate, aminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, preferably the particulate polymer B can include one or more of acrylate-based copolymer, methacrylate-based copolymer, styrene-acrylate copolymer, butadiene-styrene copolymer, hydrogenated butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, hydrogenated butadiene-acrylonitrile copolymer, polyvinylidene fluoride.

[0043] In a second aspect, the present application provides a separator adhesive comprising the separator adhesive composition as described above, and optionally a dispersing agent, a wetting agent. The dispersing agent can be a conventional dispersing agent, such as polyacrylate, sodium carboxymethyl cellulose, etc. The content of the dispersing agent in the separator adhesive can be 0.1% to 10%. The wetting agent can be a conventional wetting agent, such as alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ether, etc. The content of the wetting agent in the separator adhesive can be 0.05% to 1%. As known to those skilled in the art, the solvent in the separator adhesive described above is water. The method for preparing the separator adhesive by using the separator adhesive composition, the dispersing agent, the wetting agent, etc. is known, for example, mixing the separator adhesive composition with the dispersing agent having a content of 10% and the wetting agent having a content of 1%. According to the present application, it can be understood that the separator adhesive can be directly coated on the base film or coated on the ceramic adhesive layer. Since the particulate polymer A has a low glass transition temperature, the separator adhesive thus has a good room temperature adhesive function.

[0044] In a third aspect, the present application provides a separator comprising a base film and an adhesive layer, wherein the adhesive layer uses the separator adhesive composition or the separator adhesive as described above. The particulate polymer B has no adhesive force at room temperature, and thus mainly functions to prevent the separator from being adhered to each other at room temperature. When the separator is hot-pressed, the particulate polymer B can also provide a hot-press adhesive force, and meanwhile the particulate polymer A can also provide a higher adhesive force.

[0045] In some specific embodiments, the separator comprises a functional polymer adhesive layer, and the functional polymer adhesive layer comprises the separator adhesive composition as described above. Preferably, the single-sided coating area density of the functional polymer adhesive layer in the separator is 0.3 to 1.0 g / m 2 , and the mass ratio of the particulate polymer A to the particulate polymer B is (0.1 to 5): 1.

[0046] Further, the separator comprises a polyolefin base film and a functional polymer adhesive layer provided on at least one side of the polyolefin base film, and the functional polymer adhesive layer comprises the separator adhesive composition or the separator adhesive as described above.

[0047] Preferably, the base film is selected from at least one of a polyethylene base film, a polypropylene base film, a polypropylene-polyethylene-polypropylene laminated base film, or a non-woven fabric base film; and / or, the thickness of the base film is 3 to 12 μm.

[0048] Further, the separator can further comprise a non-conductive particle coating layer provided on at least one side of the polyolefin base film, and the non-conductive particle coating layer and the functional polymer adhesive layer are independently provided on at least one side of the polyolefin base film.

[0049] Preferably, the thickness of the non-conductive particle coating is 0.5-4 μm. Preferably, the thickness of the non-conductive particle coating is 0.5-3 μm. When the thickness of the non-conductive particle coating is less than 0.5 μm, the heat resistance of the composite separator is reduced, and the prepared battery has a greater risk of safety. When the thickness of the non-conductive particle coating is greater than 4 μm, the composite separator is too thick, and the energy density of the prepared battery is low. Further, the non-conductive particle coating comprises non-conductive particles having an average particle size of 0.1-2 μm.

[0050] Preferably, the non-conductive particle coating comprises non-conductive particles, ceramic binder, and optionally added rheological modifier, dispersant, wetting agent; the non-conductive particles include, but are not limited to, at least one of hydrated aluminum oxide, diatomic aluminum oxide, boehmite, silicon dioxide, titanium dioxide, zirconium dioxide, calcium oxide, magnesium oxide, magnesium hydroxide, calcium carbonate, barium titanate, barium sulfate, and heat-resistant organic polymer particles. In the non-conductive particle coating, the weight ratio of non-conductive particles, ceramic binder, sodium carboxymethyl cellulose, dispersant, and wetting agent is (88-96.3): (3-15): (0-3): (0-2): (0-2). Preferably, in the non-conductive particle coating, the weight ratio of non-conductive particles, ceramic binder, rheological modifier, dispersant, and wetting agent is (88-96.3): (3-15): (0.5-3): (0.1-2): (0.1-2). The role of the ceramic binder in the non-conductive particle coating is to bond the non-conductive particles to the base film. The ceramic binder can be any commercially available ceramic binder, which can be directly obtained by commercial purchase. The dispersant can be any commercially available dispersant, such as sodium polyacrylate. The wetting agent can be any commercially available wetting agent, such as any one or mixture of several of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ether, and polyether modified polysiloxane.

[0051] In a fourth aspect, the present application provides a battery comprising the separator as described above. Since the core polymer of the particulate polymer A and the particulate polymer B both have a high glass transition temperature, they will not melt into a film during high-temperature cycling of the battery, and will not affect the transmission of lithium ions inside the battery, thereby enabling the battery to have better high-temperature cycling performance.

[0052] The specific embodiments of the present application will be further explained by the following examples and comparative examples.

[0053] In the following description, the reagents, materials, and instruments used are conventional reagents, conventional materials, and conventional instruments, which are commercially available, and the reagents involved can also be synthesized by conventional synthesis methods. The methods in the examples are conventional methods in the art, unless otherwise specified.

[0054] Example 1

[0055] 1. Preparation of the separator binder composition:

[0056] Core polymer preparation: Add 150 parts of deionized water into a suitable size reaction kettle, and nitrogen is bubbled through and the temperature is raised to 80°C. Weigh 0.1 parts of sodium dodecyl sulfate and 200 parts of deionized water into another stirring container, and add 135 parts of methyl methacrylate, 14 parts of butyl acrylate, 1 part of divinyl benzene and stir to emulsify to obtain a pre-emulsion. Add the pre-emulsion and 0.8 parts of initiator into the above reaction kettle and stir to react for 6 hours, then raise the temperature to 85±1°C and continue to react for 3 hours to obtain a core polymer emulsion with a solid content of 30 wt%, and the average particle size is 0.6 μm.

[0057] Preparation of the particulate polymer A (shell layer): Weigh 1 part of sodium dodecyl sulfate and 1400 parts of deionized water into another stirring container, and add 240 parts of methyl methacrylate, 358 parts of butyl acrylate, 2 parts of divinyl benzene and stir to emulsify to obtain a pre-emulsion, which is added dropwise into the above core polymer emulsion, and continue to react for 3 hours to obtain a particulate polymer A with a solid content of 30 wt%, and the average particle size is 1 μm. 50 The average particle size is 1 μm, and the average particle size of the core polymer is 0.6 μm. 90 The glass transition temperature of the core polymer is about 81°C, and the glass transition temperature of the shell polymer is about -10°C.

[0058] The particulate polymer B is a PVDF with a particle size of 7 μm. 50 The particulate polymer B is a PVDF with a particle size of 7 μm.

[0059] Mix the particulate polymer A and the particulate polymer B in a mass ratio of 0.3:1 to obtain the binder composition.

[0060] 2. Preparation of the separator: Prepare a non-conductive particulate slurry by mixing 93.4 parts of non-conductive particulate boehmite powder, 6 parts of ceramic binder (HD2126 from Shenzhen Haodianshi Technology Co., Ltd.), 0.3 parts of dispersant sodium polyacrylate, 1 part of carboxymethyl cellulose sodium, and 0.3 parts of wetting agent alkylphenol polyoxyethylene ether. Coat the non-conductive particulate slurry on both surfaces of a polyethylene-based film with a thickness of 9 μm, and dry in a 50°C oven to form a non-conductive particulate coating on the surface of the base film.

[0061] 3. Preparation of the separator binder and the adhesive layer: Prepare the above separator binder composition into a separator binder, and apply it on the surface of the non-conductive particulate by point coating, and the coating density is 0.5 g / m 2 , and dry to obtain an adhesive layer. It should be noted that the coating method used in this example is point coating, and the coating method is not limited in actual use, including point coating, roll coating, and spraying.

[0062] 4. Preparation of the battery:

[0063] Preparation of the negative electrode sheet: 1.5% of butadiene-styrene latex (SBR), 96% of the negative electrode active material graphite, 1% of the negative electrode conductive agent conductive carbon black, and 1.5% of the thickening agent sodium carboxymethyl cellulose (CMC) were mixed, and then deionized water was added to perform stirring to prepare a negative electrode composition. The negative electrode composition was then coated on both surfaces of the negative electrode current collector copper foil, and after the processes of drying, cold pressing, slitting, and the like, a negative electrode sheet was obtained.

[0064] Preparation of the positive electrode sheet: 96% of the positive electrode active material lithium iron phosphate, 2% of the positive electrode conductive agent conductive carbon black, and 2% of the binder PVDF were added to N-methylpyrrolidone to perform stirring to prepare a positive electrode slurry. The positive electrode slurry was then coated on both surfaces of the positive electrode current collector aluminum foil, and after the processes of drying, cold pressing, slitting, and the like, a positive electrode sheet was obtained.

[0065] The separator, the positive electrode sheet, and the negative electrode sheet were sequentially stacked with the separator in the middle of the positive electrode sheet and the negative electrode sheet to play a role of isolation to prepare an electrode assembly. After 25°C 3MPa cold pressing for 1 minute, the electrode assembly was placed in an outer package, a commercially available electrolyte was injected and packaged, and then after the processes of injection, formation, and exhaust, a lithium ion battery was obtained.

[0066] Example 2

[0067] The separator adhesive composition, the separator adhesive, the separator, and the battery were prepared according to the method of Example 1, and the difference between Example 2 and Example 1 was that the monomer composition for preparing the core polymer was 110 parts of methyl methacrylate, 39 parts of butyl acrylate, and 1 part of divinylbenzene. The glass transition temperature of the core polymer of the particulate polymer A was about 43°C. The D 50 The D 90 The example was consistent.

[0068] Example 3

[0069] The separator adhesive composition, the separator adhesive, the separator, and the battery were prepared according to the method of Example 1, and the difference between Example 3 and Example 1 was that the monomer composition for preparing the core polymer was 149 parts of methyl methacrylate and 1 part of divinylbenzene. The glass transition temperature of the core polymer of the particulate polymer A was about 107°C. The D 50 The D 90 The example was consistent.

[0070] Example 4

[0071] A separator adhesive composition, separator adhesive, separator and battery were prepared according to the method of Example 1, except that in Example 9 the monomer composition used to prepare the particulate polymer A was 60 parts of methyl methacrylate, 538 parts of isooctyl acrylate, and 2 parts of divinyl benzene. The shell polymer of the particulate polymer A had a glass transition temperature of about -55°C. The particulate polymer A had a D 50 The particulate polymer A had a D 90 The particulate polymer A had a D

[0072] Example 5

[0073] A separator adhesive composition, separator adhesive, separator and battery were prepared according to the method of Example 1, except that in Example 5 the monomer composition used to prepare the particulate polymer A was 418 parts of methyl methacrylate, 180 parts of isooctyl acrylate, and 2 parts of divinyl benzene. The shell polymer of the particulate polymer A had a glass transition temperature of about 26°C. The particulate polymer A had a D 50 The particulate polymer A had a D 90 The particulate polymer A had a D

[0074] Example 6

[0075] A separator adhesive composition, separator adhesive, separator and battery were prepared according to the method of Example 1, except that in Example 6 the amount of sodium dodecyl sulfate used to prepare the core polymer was 1 part, and the core polymer had a particle size of 0.2 μm. The particulate polymer A had a particle size D 50 of about 0.4 μm, and the particulate polymer A had a particle size D 90 of about 0.5 μm.

[0076] Example 7

[0077] A separator adhesive composition, separator adhesive, separator and battery were prepared according to the method of Example 1, except that in Example 7 the total amount of monomer pre-emulsion used to prepare the particulate polymer A was 1 / 4 of that used in Example 1. The particulate polymer A had a particle size D 50 of about 0.8 μm, and the particulate polymer A had a particle size D 90 of about 1 μm.

[0078] Example 8

[0079] A separator adhesive composition, separator adhesive, separator and battery were prepared according to the method of Example 1, except that in Example 8 the total amount of monomer pre-emulsion used to prepare the particulate polymer A was 1 / 16 of that used in Example 1. The particulate polymer A had a particle size D 50 of about 0.65 μm, and the particulate polymer A had a particle size D 90 of about 0.8 μm.

[0080] Example 9

[0081] A separator binder composition, separator binder, separator and battery were prepared according to the method of Example 1, with the difference between Example 9 and Example 1 being that the particulate polymer B was HD2121 from Shenzhen Haodianshi Technology Co., Ltd., the particle size D 50 was 5 μm, and the glass transition temperature was 55 °C.

[0082] Example 10

[0083] A separator binder composition, separator binder, separator and battery were prepared according to the method of Example 1, with the difference between Example 10 and Example 1 being that the particulate polymer B was prepared according to the following method:

[0084] Step 1: 20 parts of monomers were mixed with 0.5 parts of dilauroyl peroxide, and stirred and dissolved uniformly to form a mixed monomer; the monomers used in this example were a mixture of 120 parts of styrene, 22.5 parts of butyl acrylate, 6 parts of isooctyl acrylate, and 1.5 parts of divinyl benzene;

[0085] Step 2: polyvinyl alcohol 1788 was dissolved in 80 parts of deionized water to prepare an aqueous dispersion of the dispersant, and the concentration of the dispersant was 0.5 wt%;

[0086] Step 3: the mixed solution of Step 1 was poured into the aqueous dispersion of the dispersant of Step 2, and a high-speed homogenizer was used to homogenize the oil-water dispersion at a speed of 2000 rpm;

[0087] Step 4: after 30 minutes of nitrogen blowing, the temperature was raised for polymerization, the polymerization temperature was 75 °C, and the polymerization time was 6 hours; after the polymerization was completed, a water dispersion of a styrene-acrylate copolymer with a solid content of 25% was obtained, and the particle size D 50 of the particulate polymer B in the water dispersion was 9.5 μm, and the glass transition temperature was 55 °C.

[0088] Example 11

[0089] A separator binder composition, separator binder, separator and battery were prepared according to the method of Example 1, with the difference between Example 11 and Example 1 being that the particulate polymer B was prepared according to the method of Example 10, the speed of the homogenizer was 15000 rpm, and the particle size D 50 of the particulate polymer B was 1 μm, and the glass transition temperature was 55 °C.

[0090] Example 12

[0091] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the particulate polymer B was produced in the same manner as in Reference Example 10, the homogenizer rotation speed was 2200 rpm, and the particle size D 50 of the particulate polymer B was 8 μm and the glass transition temperature was 55°C.

[0092] Example 13

[0093] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the particulate polymer B was produced in the same manner as in Reference Example 10, the homogenizer rotation speed was 10000 rpm, the monomer composition was 149 parts of methyl methacrylate and 1 part of divinylbenzene, and the particle size D 50 of the particulate polymer B was 5 μm and the glass transition temperature was 108°C.

[0094] Example 14

[0095] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the mass ratio of the particulate polymer A to the particulate polymer B was 0.1:1.

[0096] Example 15

[0097] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the mass ratio of the particulate polymer A to the particulate polymer B was 5:1.

[0098] Example 16

[0099] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the coating surface density of the separator adhesive was 0.2 g / m 2 .

[0100] Example 17

[0101] A separator adhesive composition, a separator adhesive, a separator and a battery were produced in the same manner as in Example 1, except that the coating surface density of the separator adhesive was 1 g / m 2 .

[0102] Example 18

[0103] The membrane binder composition, membrane binder, membrane, and battery were prepared according to the method of Example 1. The difference between Example 18 and Example 1 is that the preparation methods of the particulate polymer A and particulate polymer B are both the same as those used in Example 10 for preparing particulate polymer B. Particulate polymer A has a uniform core-shell-free structure, the homogenizer speed is 15000 rpm, and the monomer composition is 99 parts styrene, 50 parts isooctyl acrylate, and 1 part divinylbenzene. The particle size D of particulate polymer A is... 50 1μm, D 90 The particle size is 2 μm, and the glass transition temperature is 25 °C. The particulate polymer B is the same as in Example 1.

[0104] Example 19

[0105] The membrane adhesive composition, membrane adhesive, membrane, and battery were prepared according to the method of Example 1. The difference between Example 19 and Example 1 is that the preparation methods of the particulate polymer A and particulate polymer B are both the same as those used in Example 10 for preparing particulate polymer B. Particulate polymer A has a uniform core-shell-free structure, the homogenizer speed is 9000 rpm, and the monomer composition is 99 parts styrene, 50 parts isooctyl acrylate, and 1 part divinylbenzene. The particle size D of particulate polymer A is... 50 6μm, D 90 The particle size is 14 μm, and the glass transition temperature is 25 °C. The monomer composition of the particulate polymer B is the same as in Example 10. The homogenizer speed is 1000 rpm. The glass transition temperature of the particulate polymer B is 55 °C, and the particle size D is... 50 It is 20μm.

[0106] Comparative Example 1

[0107] The membrane adhesive composition, membrane adhesive, membrane, and battery were prepared according to the method of Example 1. The difference between Comparative Example 1 and Example 1 is that the shell monomer composition of the particulate polymer A is 99 parts methyl methacrylate, 50 parts butyl acrylate, and 1 part divinylbenzene. The glass transition temperature of the core polymer of the particulate polymer A is 80°C, and the glass transition temperature of the outer shell polymer is 33°C.

[0108] Comparative Example 2

[0109] The membrane binder composition, membrane binder, membrane, and battery were prepared according to the method of Example 1. The difference between Comparative Example 2 and Example 1 is that the total amount of monomer pre-emulsion in the preparation of particulate polymer A is 1 / 20 of that in Example 1, and the particle size D of particulate polymer A is... 50 The particle size of the particulate polymer A is approximately 0.6 μm. 90 It is approximately 0.7 μm.

[0110] Comparative Example 3

[0111] A separator adhesive composition, a separator adhesive, a separator and a battery were produced according to the method of Example 1, with the exception that the granular polymer A was produced according to the method of Example 6, and the granular polymer B was produced according to the method of Example 10. 50 The particle size D of the granular polymer A was about 1.1 μm, and the glass transition temperature was 55°C. 90 The particle size D of the granular polymer A was about 1.4 μm.

[0112] Comparative Example 4

[0113] A separator adhesive composition, a separator adhesive, a separator and a battery were produced according to the method of Example 1, with the exception that the granular polymer B was produced according to the method of Example 13, the homogenizer rotation speed was 14000 rpm, the monomer composition was methyl methacrylate 119 parts, butyl acrylate 30 parts, divinyl benzene 1 part, and the particle size D of the granular polymer B was 1.5 μm, and the glass transition temperature was 55°C. 50 The particle size D of the granular polymer A was about 1.1 μm, and the glass transition temperature was 55°C.

[0114] Comparative Example 5

[0115] A separator adhesive composition, a separator adhesive, a separator and a battery were produced according to the method of Example 1, with the exception that the granular polymer A was the same as that of Example 6, and the granular polymer B was the same as that of Example 10.

[0116] Comparative Example 6

[0117] A separator adhesive composition, a separator adhesive, a separator and a battery were produced according to the method of Example 1, with the exception that the granular polymer B was produced according to the method of Example 13, the monomer composition was methyl methacrylate 119 parts, butyl acrylate 30 parts, divinyl benzene 1 part, and the particle size D of the granular polymer B was 5 μm, and the glass transition temperature was 45°C. 50 The particle size D of the granular polymer A was about 1.1 μm, and the glass transition temperature was 55°C.

[0118] Comparative Example 7

[0119] A separator adhesive composition, a separator adhesive, a separator and a battery were produced according to the method of Example 1, with the exception that the granular polymer A was the same as that of Example 6. The granular polymer B was produced according to the method of Example 7, with the exception that the monomer composition for the core polymer and the shell polymer was the same, i.e., methyl methacrylate 119 parts, butyl acrylate 30 parts, divinyl benzene 1 part. The particle size D of the granular polymer B was 0.8 μm. 50 The particle size D of the granular polymer A was about 1.1 μm, and the glass transition temperature was 55°C.

[0120] Comparative Example 8

[0121] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the granular polymer A was the same as in Example 18, and the granular polymer B was produced in the same manner as in Example 10, the homogenizer rotation speed was 900 rpm, the monomer composition was 119 parts of methyl methacrylate, 30 parts of butyl acrylate, and 1 part of divinylbenzene, and the particle size D 50 of the granular polymer B was 22 μm, and the glass transition temperature was 55°C.

[0122] Comparative Example 9

[0123] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the mass ratio of the granular polymer A to the granular polymer B was 0.08:1.

[0124] Comparative Example 10

[0125] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the mass ratio of the granular polymer A to the granular polymer B was 5.5:1.

[0126] Comparative Example 11

[0127] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the coating surface density of the separator binder was 0.15 g / m 2 .

[0128] Comparative Example 12

[0129] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the coating surface density of the separator binder was 1.05 g / m 2 .

[0130] Comparative Example 13

[0131] A separator binder composition, a separator binder, a separator and a battery were produced in the same manner as in Example 1, except that the granular polymer A was the same as in Example 18. The granular polymer B was produced in the same manner as in Example 10, except that the homogenizer rotation speed was 1700 rpm, and the monomer composition was 119 parts of methyl methacrylate, 30 parts of butyl acrylate, and 1 part of divinylbenzene, and the particle size D 50 of the granular polymer B was 12 μm, and the glass transition temperature was 55°C.

[0132] Performance Test:

[0133] The separator adhesive composition, the separator adhesive, the separator and the battery prepared in the above examples and comparative examples were subjected to the following performance tests.

[0134] 1. 25℃ room temperature peel strength test: the functional separator prepared by the scheme of the present application and the negative electrode sheet were respectively cut into 20mm*100mm strips, and the side containing the adhesive of the separator was pressed against the negative electrode sheet at 25℃ and 3MPa for 60s, and the 180° peel strength test was performed using an electronic tensile testing machine, and the test results were averaged from 3 samples.

[0135] 2. 85℃ high temperature peel strength test: the functional separator prepared by the scheme of the present application and the negative electrode sheet were respectively cut into 20mm*100mm strips, and the side containing the adhesive of the separator was pressed against the negative electrode sheet at 85℃ and 1.5MPa for 60s, and the 180° peel strength test was performed using an electronic tensile testing machine, and the test results were averaged from 3 samples.

[0136] 3. Separator unwinding self-adhesion verification: the separator coated with the separator adhesive composition was wound for 2000 meters, and after being stored at room temperature for 3 days, the separator was unwound, and whether there was self-adhesion was observed.

[0137] 4. 30℃ 1Mpa separator self-adhesion simulation test: the functional separator coated with the separator adhesive on both sides was pressed at 30℃ and 1MPa for 60s, and the peel strength between the separators was tested. The adhesion force ≤0.5N / m was regarded as no self-adhesion between the separators.

[0138] 5. Battery internal resistance test: after the battery was divided into groups, the AC internal resistance was tested using an AC low resistance tester, with the unit mΩ.

[0139] 6. 45℃ high temperature cycle performance test: the battery was placed in a constant temperature test room at 45℃±1°C for 1h, then charged at 1C constant current and constant voltage to 3.65V, with the cutoff current being 0.05C; discharged at 1C constant current to 2V, and the discharge capacity was recorded; the above steps were repeated 500 times, and the capacity retention rate was calculated.

[0140] The performance test results of each example and comparative example are shown in Table 1.

[0141] Table 1

[0142] As can be seen from the test results of Examples 1-19, the separator prepared by using the binder composition according to the technical scheme of the present application has good adhesion at room temperature (25℃), and the separator does not produce self-adhesion, and the prepared battery cell has excellent cycle performance. The glass transition temperature (Tg) of the particulate polymer A has a significant influence on the room temperature adhesion, and within the preferred range of the present application, the lower the glass transition temperature of the particulate polymer A, the better the room temperature adhesion, and the more the content of the low Tg portion in the particulate polymer A, the better the room temperature adhesion. Within the preferred range of the present application, the lower the D2 / D1 ratio and the lower the D2 / D3 ratio, the better the room temperature adhesion and the comprehensive performance of preventing self-adhesion.

[0143] As can be seen from the test results of Example 1 and Comparative Example 1, when the Tg of the particulate polymer A is higher than 30℃, the room temperature adhesion decreases, the adhesion between the separator and the pole piece is insufficient, and the cycle performance of the battery decreases. As can be seen from the results of Example 1 and Comparative Examples 2-3, when the low Tg component in the particulate polymer A is too little and the D1 / D2 ratio is too low, the adhesion is insufficient. When the Tg of the particulate polymer B is too low, the separator is prone to self-adhesion after being pressed at 30℃. When the particle size of the particulate polymer B is too small, the separator is prone to self-adhesion, and when the particle size is too large, the adhesion is insufficient. As can be seen from the test results of Comparative Example 13 and Examples 1-19, when the D 90 of the particulate polymer A is higher than the D 50 of the particulate polymer B, the separator is prone to self-adhesion.

[0144] When the particulate polymer A does not have a core-shell structure, due to the low glass transition temperature of the particulate polymer A, the coating and baking are prone to form a film, resulting in an increase in the internal resistance of the battery. Similarly, if the glass transition temperature of the particulate polymer B is low, it is also prone to cause an increase in the internal resistance of the battery.

[0145] In summary, the binder composition according to the present application successfully achieves a perfect balance between room temperature adhesion and prevention of self-adhesion, and significantly improves the high-temperature life of the battery.

[0146] The above further describes the present application with the aid of specific examples, but it should be understood that the specific description herein should not be understood as limiting the essence and scope of the present application, and various modifications made by those skilled in the art to the above examples after reading the present specification are within the scope of the present application.

Claims

1. A diaphragm adhesive composition, characterized in that, It includes particulate polymer A and particulate polymer B; the glass transition temperature of polymer A is not higher than 30°C; the D of particulate polymer B... 50 The particle size is larger than that of the particulate polymer A. 90 Particle size; Wherein, the particulate polymer B is a polyvinylidene fluoride polymer or a fluorine-free polymer, and when the particulate polymer B is a fluorine-free polymer, the glass transition temperature of the particulate polymer B is not lower than 50°C.

2. The diaphragm adhesive composition according to claim 1, characterized in that, The mass ratio of the particulate polymer A to the particulate polymer B is (0.1~5):

1.

3. The diaphragm adhesive composition according to claim 1, characterized in that, The glass transition temperature of the particulate polymer A is -60℃ to 30℃.

4. The diaphragm adhesive composition according to claim 1, characterized in that, The particulate polymer A comprises a core polymer and a shell polymer disposed on the surface of the core polymer, wherein the mass ratio of the core polymer to the shell polymer is (1~4):(4~1). And / or, the glass transition temperature of the core polymer is 40℃~110℃; the glass transition temperature of the shell polymer is -60℃~30℃.

5. The diaphragm adhesive composition according to claim 1, characterized in that, The particulate polymer B's D 50 Particle size D2 and the D of the particulate polymer A 90 The particle size ratio D3 is (1.1~40):1; And / or, the D of the particulate polymer B 50 Particle size D2 and the D of the particulate polymer A 50 The ratio of particle size D1 is (2~25):1; And / or, the D of the particulate polymer A 50 The particle size D1 is 0.4~6μm; And / or, the D of the particulate polymer B 50 Particle size D2 is 1~20μm; And / or, the D of the particulate polymer A 90 The particle size D3 is 0.5~15μm.

6. The diaphragm adhesive composition according to claim 1, characterized in that, The glass transition temperature of the particulate polymer B is 50℃~110℃.

7. The diaphragm adhesive composition according to claim 4, characterized in that, The core polymer and the shell polymer respectively contain one or more of the following: benzene ring structural units, cyano structural units, and ester structural units; And / or, the particulate polymer B comprises one or more of the following structural units: benzene ring structural units, cyano structural units, ester structural units, and vinylidene fluoride structural units.

8. A diaphragm adhesive, characterized in that, Includes the diaphragm adhesive composition as described in any one of claims 1-7.

9. A diaphragm, characterized in that, It includes a substrate and an adhesive layer, the adhesive layer using a diaphragm adhesive composition as described in any one of claims 1-7 or the diaphragm adhesive as described in claim 8.

10. A battery, characterized in that, Includes the diaphragm as described in claim 9.

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