Separator and manufacturing method thereof, battery and power consumption device

Abstract

The present application discloses a separator and a method for manufacturing the same, a battery and a power consuming device, wherein the separator comprises a substrate and a coating, the coating is formed on at least a portion of a surface of the substrate, the coating comprises composite particles and an adhesive, the composite particles form protrusions on the coating surface, the composite particles comprise polyacrylate particles and first inorganic particles, and have the first inorganic particles between at least two of the polyacrylate particles.

Description

[Technical Field]

[0001] The present application relates to the field of secondary battery technology, and more particularly to a separator and its manufacturing method, a battery, and a power consuming device. [Background technology]

[0002] 2. Description of the Related Art Secondary batteries have prominent features such as light weight, pollution-free, and no memory effect, and are therefore widely used in various consumer electronic products and electric vehicles.

[0003] With the continuous development of the new energy industry, users have higher usage demands for secondary batteries, for example, secondary batteries are designed to have higher and higher energy densities, but the increase in battery energy density is often unfavorable to the balance of electrochemical performance or safety performance.

[0004] Therefore, how to simultaneously achieve both cycle performance and safety performance in a battery is a key challenge in the field of battery design. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the technical problems existing in the background art, the present application aims to provide a separator that allows a battery including the separator to simultaneously achieve good cycle performance and safety performance. [Means for solving the problem]

[0006] To achieve the above object, according to a first aspect of the present application, there is provided a separator comprising a substrate and a coating, the coating being formed on at least a portion of the surface of the substrate, the coating comprising composite particles and an adhesive, the composite particles forming protrusions on the coating surface, the composite particles comprising polyacrylate particles and first inorganic particles, and the first inorganic particles being disposed between at least two of the polyacrylate particles.

[0007] Compared with the prior art, the present application has at least the following beneficial effects: In the actual application process of a battery module, with the continuous charging and discharging, the plates inevitably expand, and when the module space is limited, the expansion force cannot be released and acts against the cell battery core, which causes the adhesive effect between the separator coating and the plates to be too strong, destroying the separation of lithium ions and even causing the separator coating to large The separator coating used in the present application includes composite particles and an adhesive, and the composite particles include polyacrylate particles and first inorganic particles, and at least two Polyacrylate The presence of first inorganic particles between the particles prevents the composite particles from sticking together during the high-temperature granulation process, improving the ion conduction ability of the separator and increasing the compressive modulus of the composite particles, thereby achieving a relatively suitable adhesion between the separator and the electrode plates. Compared to conventional separator coatings that use polyvinylidene fluoride particles, the separator coating of the present application includes composite particles and an adhesive, which reduces separator resistance and ensures a suitable adhesion between the separator and the electrode plates during battery core fabrication and use. Most importantly, it provides the separator with a suitable compressive modulus, ensuring that the battery core does not block lithium ion transmission channels and deteriorate dynamic performance when cycle expansion force increases, thereby improving the dynamic performance of the battery. At the same time, when the battery experiences thermal runaway and high temperatures, the protrusions formed on the coating surface by the composite particles form a large-area adhesive film structure, reducing or blocking ion transmission channels and extending the heat dissipation of the battery, thereby effectively improving the battery's cycle performance and safety performance at high temperatures.

[0008] In some embodiments of the present application, the compressive modulus of the separator is a MPa, the mass occupancy of the first inorganic particles in the composite particles is b wt%, and a / b is 1.1-60, preferably 4.7-34, so that the adhesion between the separator and the electrode plate is adequate.

[0009] In some embodiments of the present application, the separator has a compressive modulus of elasticity aMpa of 60 MPa-90 MPa, so that the adhesion between the separator and the electrode plate is adequate.

[0010] In some embodiments of the present application, the content (wt%) of the first inorganic particles in the composite particles is 1 wt%-50 wt%, preferably 1 wt%-40 wt%, more preferably 2 wt%-15 wt%, and most preferably 5 wt%-15 wt%, so as to obtain a suitable compressive modulus of the separator.

[0011] In some embodiments of the present application, the Dv50 of the composite particles is 2.5 μm or more, preferably 2.5 μm-10 μm, more preferably 3 μm-8 μm, which is advantageous for forming a protrusion structure on the coating surface, thereby improving the dynamic performance of the battery core.

[0012] In some embodiments of the present application, the composite particles include first aggregates, and the first aggregates include at least two of the first inorganic particles, thereby improving the kinetic performance of the battery.

[0013] In some embodiments of the present application, Dv50 of the first agglomerates is 0.01 μm≦Dv10 of the composite particles, thereby increasing the compressive modulus of the separator.

[0014] In some embodiments of the present application, the composite particles include first inorganic particles in the form of primary particles.

[0015] In some embodiments of the present application, the Dv50 of the first inorganic particles in the form of primary particles is 0.01 μm-1 μm, preferably 0.5 μm-1 μm, to ensure that the composite particles do not fuse together during the fabrication process and block the separator ion transport channels.

[0016] In some embodiments of the present application, the composite particles comprise second agglomerates, and the second agglomerates comprise at least two of the polyacrylate particles.

[0017] In some embodiments of the present application, the Dv50 of the second aggregates is 0.3 μm-5 μm, preferably 1 μm-2 μm.

[0018] In some embodiments of the present application, the polyacrylate particles include polyacrylate particles in the form of primary particles and / or polyacrylate particles in the form of secondary particles.

[0019] In some embodiments of the present application, the Dv50 of the primary particle form polyacrylate particles is 50 nm-400 nm, preferably 100 nm-200 nm, which can improve the ion conduction ability of the entire separator coating, reduce the separator resistance, and improve the dynamic performance of the battery core.

[0020] In some embodiments of the present application, the Dv50 of the secondary particle-form polyacrylate particles is 2 μm-15 μm, preferably 5 μm-8 μm, which provides a buffer space for stress relief between the electrodes and prevents the corners of the wound battery core from breaking due to stress accumulation.

[0021] In some embodiments of the present application, the height of each of the two surfaces of the protrusions is 15 μm-60 μm, which can improve the dynamic performance of the battery core while improving the battery safety.

[0022] In some embodiments of the present application, the surface of the protrusions has the first agglomerates, which can improve the dynamic performance of the battery.

[0023] In some embodiments of the present application, the coating comprises composite particles and an adhesive, the adhesive comprising an adhesive polymer and a plasticizer, the adhesive polymer comprising a copolymer formed from at least one of a first monomer, at least one of a second monomer, at least one of a third monomer, and at least one reactive dispersant, as follows: First monomers: acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, acrylonitrile; Second monomer: acrylic acid C4-C22 alkyl ester, isobutyl acrylate, isooctyl acrylate, tert-butyl acrylate, 2-ethylhexyl (isooctyl) acrylate, cyclohexyl acrylate, ethyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate Lu, Me Acrylic Acid Lu Including, Third monomer: 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, gamma-Methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, methacrylic acid, ethyl acetoacetate, divinylbenzene, epoxy resin with an epoxy value of 0.35-0.50, including divinylbenzene; Reactive dispersants: include polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, polyvinyl alcohol.

[0024] In some embodiments of the present application, the plasticizer comprises at least one of a glycerol C4-C10 alkyl diether, a glycerol C4-C10 alkyl monoether, a glycerol C4-C10 carboxylic acid monoester, a glycerol C4-C10 carboxylic acid diester, a propylene glycol C4-C10 alkyl monoether, and glycerol.

[0025] In some embodiments of the present application, the coating comprises composite particles, second inorganic particles, and an adhesive, wherein the adhesive comprises a linear copolymer having a hydroxyl group and a carboxylate group, the linear copolymer comprising a polymerization product of various monomers such as: (1) a first type of monomer, the first type of monomer comprising at least one of acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, and acrylonitrile; (2) a second type of monomer, the second type of monomer comprising at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, cyclohexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-hexyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, ethylene urea ethyl methacrylate, acrylic methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, and trifluoroethyl methacrylate; (3) a third type of monomer, the third type of monomer including at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl (meth)acrylamide, diacetoneacrylamide, methacrylic acid, ethyl acetoacetate, divinylbenzene, and an epoxy resin having an epoxy value of 0.35 to 0.50; (4) A fourth type of monomer, wherein the fourth type of monomer includes at least one of polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, and polyvinyl alcohol.

[0026] As a result, the linear copolymer containing the above monomer allows the adhesive to have good wettability with the substrate, thereby increasing the yield rate of substrate application and improving coating density. More importantly, it improves the adhesion between the second inorganic particles and composite particles and the substrate, significantly improving the heat shrinkage performance of the separator, thereby improving the safety performance of the battery core. It can also generate chemical reactions with the particle materials in the coating, thereby creating an appropriate dense structure and further improving the safety of the separator. This three-dimensional interaction also penetrates the transmission channels of lithium ions, increasing the ionic electrical conductivity of the separator and improving the dynamic performance of the battery core.

[0027] In some embodiments of the present application, the Dv50 of the composite particles is greater than that of the second inorganic particles, which is advantageous for forming protrusions on the coating surface, thereby improving the battery safety and the dynamic performance of the battery core.

[0028] In some embodiments of the present application, the Dv50 of the second inorganic particles is 0.5 μm-2 μm, preferably 1 μm-2 μm, thereby improving the high temperature resistance of the separator.

[0029] In some embodiments of the present application, the mass ratio of the composite particles to the second inorganic particles is (5-30):(50-70), which can improve the dynamic performance of the battery.

[0030] In some embodiments of the present application, the mass ratio of the composite particles to the solid content of the adhesive is (80-90):(5-20), preferably (85-90):(8-15), which can improve the cycle performance and safety performance of the battery.

[0031] In some embodiments of the present application, the coating further comprises organic particles, including at least one of polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylic acid-based monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylate-based monomer units, and particles of modified compounds of the above homopolymers or copolymers, and the organic particles and the composite particles form the protrusions on the coating surface, thereby improving the cycle performance and safety performance of the battery.

[0032] In some embodiments of the present application, the organic particles form third aggregates.

[0033] In some embodiments of the present application, the Dv50 of the third aggregates is 5 μm-30 μm, preferably 5.0 μm-12 μm.

[0034] In some embodiments of the present application, the third aggregates include organic particles in the form of primary particles, and there are gaps between adjacent two of the organic particles, thereby improving the ionic conductivity of the separator.

[0035] In some embodiments of the present application, the Dv50 of the organic particles in the form of primary particles is 50 nm-400 nm, preferably 100 nm-200 nm.

[0036] In some embodiments of the present application, the mass ratio of the composite particles to the organic particles is (20-90):(0-70), preferably (45-90):(0-45), which can reduce the battery cost while improving its safety performance and cycle performance.

[0037] According to a second aspect of the present application, there is provided a method for manufacturing a separator, the method comprising: (1) providing a substrate; and (2) forming a coating comprising composite particles and an adhesive on at least a portion of a surface of the substrate, the composite particles forming protrusions on the coating surface, the composite particles comprising polyacrylate particles and first inorganic particles, and the first inorganic particles being disposed between at least two of the polyacrylate particles.

[0038] Therefore, the separator has excellent compressive modulus and proper adhesion between the separator and the electrode plates, thereby enhancing the cycle performance of the battery and at the same time improving its safety performance.

[0039] According to a third aspect of the present application, there is provided a battery, the battery including a separator according to the first aspect of the present application or a separator produced by the method according to the second aspect of the present application. The battery according to the present application has excellent safety performance and cycle performance because it includes a separator according to the above aspect of the present application or a separator produced by the above method.

[0040] According to a fourth aspect of the present application, there is provided a power consuming device, the power consuming device comprising a battery according to the third aspect of the present application, the battery being adapted to provide electrical energy. Because the power consuming device of the present application comprises a battery according to the above aspect of the present application, the power consuming device of the present application has at least the same advantages as the battery. [Brief explanation of the drawings]

[0041] In order to more clearly explain the technical solution of the present application, the following briefly introduces the drawings used in the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] 1 is a cross-sectional view (CP) of a separator according to an embodiment of the present application. [Figure 2] 10 is a cross-sectional view (CP) of a separator according to another embodiment of the present application. [Figure 3] 10 is a cross-sectional view (CP) of a separator according to another embodiment of the present application. [Figure 4] 1 is a schematic view of a battery core wound after stacking separators, positive electrode plates, and negative electrode plates in an embodiment of the present application. FIG. [Figure 5] 1 is a scanning electron microscope image (SEM image) of a separator according to an embodiment of the present application. [Figure 6] 1 is a structural schematic diagram of a separator according to an embodiment of the present application. [Figure 7] FIG. 10 is a structural schematic diagram of a separator according to still another embodiment of the present application. [Figure 8] 1 is a structural schematic diagram of a battery according to an embodiment of the present application; [Figure 9] 1 is a structural schematic diagram of a battery module according to an embodiment of the present application; [Figure 10] 1 is a structural schematic diagram of a battery pack according to an embodiment of the present application; [Figure 11] FIG. 11 is an exploded view of FIG. [Figure 12] 1 is a schematic diagram of one embodiment of a power consuming device that uses a battery as a power source. DETAILED DESCRIPTION OF THE INVENTION

[0042] The present application will be further described in detail below in conjunction with the detailed description of the present application, and it should be understood that these specific embodiments are merely for the purpose of illustrating the present application, and are not intended to limit the scope of the present application.

[0043] For clarity, this specification specifically discloses only some numerical ranges. However, any lower limit and any upper limit can be combined to form a range not expressly stated, and any lower limit and any other lower limit can be combined to form a range not expressly stated, and similarly, any upper limit and any other upper limit can be combined to form a range not expressly stated. Furthermore, each individually disclosed point or single numerical value itself can be combined with any other point or single numerical value as a lower limit or upper limit, or with any other lower limit or upper limit, to form a range not expressly stated.

[0044] In the description of this specification, unless otherwise specified, the term "or" is inclusive. That is, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0045] In the description of this specification, it should be explained that unless otherwise specified, "more than" and "less than" are inclusive, and "multiple" in "one or more" means two and more than two.

[0046] Unless otherwise specified, the terms used in this application have the known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of each parameter mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0047] An embodiment of the present application provides a separator, the separator including a substrate and a coating, the coating being formed on at least a portion of the surface of the substrate, the coating including composite particles and an adhesive, the composite particles forming protrusions on the coating surface, the composite particles including polyacrylate particles and first inorganic particles, and the first inorganic particles being disposed between at least two of the polyacrylate particles.

[0048] It should be noted that the coating formed on at least a portion of the surface of the substrate can be understood as meaning that the coating is in direct contact with the surface of the substrate, i.e., "direct contact," or that there is another layer between the substrate surface and the coating, i.e., "indirect contact." At the same time, the phrases "first inorganic particles are present between at least two of the polyacrylate particles" and "composite particles form protrusions on the coating surface" can be understood by cutting the separator along its thickness direction and scanning the separator coating cross section with a scanning electron microscope (SEM). From the SEM image, it can be seen that the composite particles contain polyacrylate particles and first inorganic particles, that the first inorganic particles are present between some of the polyacrylate particles, and that the composite particles form protrusions on the coating surface.

[0049] Specifically, the test was performed using a ZEISS Sigma300 scanning electron microscope, following the steps below: First, cut the separator to be tested into a 6mm x 6mm sample, sandwich the sample between two pieces of conductive and thermally conductive copper foil, secure the sample to the copper foil with double-sided tape, and press it with a 400g flat iron block for one hour until the gap between the sample to be tested and the copper foil is as small as possible. Then, cut the edges with scissors so that they are flush with each other, and place the sample on a sample holder with conductive adhesive so that the sample protrudes slightly beyond the edge of the sample holder. Then, place the sample holder on the sample shelf and lock it in place. Then, turn on the IB-19500CP argon ion cross-section polisher and perform 1 hour of pressure testing. 0-4 P A vacuum is drawn to a, the argon gas flow is set to 0.15 MPa, the voltage is set to 8 KV, and the polishing time is set to 2 hours. The sample stage is adjusted to the oscillation mode and polishing begins. After polishing is completed, a ZEISS Sigma300 scanning electron microscope is used to obtain an ion-polished cross-sectional morphology (CP) image of the sample to be tested.

[0050] According to one example, the preparation of the composite particles of the present application may refer to the following steps.

[0051] (1) providing a polymer monomer for producing polyacrylate particles, and polymerizing the polymer monomer to obtain a polyacrylate polymer; (2) adding a solvent and first inorganic particles to the polyacrylate polymer obtained in step (1), and stirring to obtain a mixed slurry; (3) The mixed slurry of step (2) is dried to remove the solvent, and then polished and crushed to obtain the composite particles described in the present application.

[0052] It should be noted that the polymerization of the polymer monomer can be carried out by adopting a polymerization method commonly used in the art, for example, emulsion polymerization or suspension polymerization.

[0053] In some embodiments, in step (1), additives such as an emulsifier such as sodium dodecyl sulfate and a polymerization initiator such as ammonium persulfate may be further added to the polymerization system of the polymer monomer.

[0054] In some embodiments, in step (1), the polymeric monomers from which the polyacrylate particles are made include at least the following polymeric monomers: a first polymer monomer having at least one ester linkage and optionally one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate, trifluoroethyl methacrylate, glycidyl methacrylate, or trimethylolpropane triacrylate; a second polymer monomer having at least one cyano bond and optionally one or more of acrylonitrile, methacrylonitrile, ethacrylonitrile, and further optionally one or more of acrylonitrile, methacrylonitrile; A third polymer monomer, which has at least one amide bond and is optionally one or more of acrylamide, N-methylolacrylamide, N-butoxymethacrylamide, and further optionally one or more of acrylamide, N-methylolacrylamide.

[0055] Therefore, the polyacrylate particles are polymerized by adopting at least the above three polymer monomers, so that the separator can obtain proper adhesion with the electrode plates, and improve the dynamic performance of the battery.

[0056] In some embodiments, the weight ratio of the first polymeric monomer to the second polymeric monomer to the third polymeric monomer in the formed polyacrylate particles is 1:0-0.8:0.05-0.75, such as 1:0.1-0.8:0.05-0.75, 1:0.1-0.7:0.05-0.75, 1:0.2-0.6 1:0-0.8:0.05-0.75, 1:0.3-0.5:0.05-0.75, 1:0.3-0.4:0.05-0.75, 1:0-0.8:0.05-0.7, 1:0-0.8:0.1-0.7, 1:0-0.8:0.15-0.65, 1:0-0.8:0.2-0.6, 1:0-0.8:0.3-0.5, or 1:0-0.8:0.4, thereby improving the dynamic performance of the battery. In some embodiments, the weight ratio of the first polymeric monomer, the second polymeric monomer, and the third polymeric monomer in the formed polyacrylate particles is 1:0.1-0.6:0.1-0.6.

[0057] In some embodiments, in step (2), the first inorganic particles include one or more of oxides of silicon, aluminum, calcium, zinc, magnesium, and sodium sulfate, sodium benzoate, calcium carbonate, and modified materials thereof, and optionally one or more of silicon dioxide, silica sol, aluminum oxide, zinc oxide, magnesium oxide, and sodium benzoate, and further optionally one or more of fumed silicon dioxide, silicon fine powder, aluminum oxide, and sodium benzoate.

[0058] Without wishing to be limited by any theory, the inventors have found after extensive research that in the actual application process of a battery module, with the constant charging and discharging, the plates will inevitably expand, and when the module space is limited, the expansion force cannot be released and acts against the cell battery core, causing the adhesion between the separator coating and the plates to become too strong, disrupting the separation of lithium ions, and even causing the separator coating to collapse over a large area, blocking the holes in the separator, affecting the transmission of lithium ions, and thereby shortening the service life of the battery core. The separator coating of the present application includes composite particles and an adhesive. The composite particles are bonded to the substrate via the adhesive. The composite particles include polyacrylate particles and first inorganic particles, with the first inorganic particles located between at least two polyacrylate particles in the composite particles. On the one hand, the presence of the first inorganic particles in the composite particles prevents adhesion between the polyacrylate particles due to high temperature treatment in the granulation process. When the polyacrylate particles are used in a separator coating, the adhesion hinders ion transmission, thereby reducing the ion conduction ability of the separator. On the other hand, because the polyacrylate particles themselves have a relatively low compressive modulus, when used alone in a separator coating, they are likely to clog pores in the separator under pressure, which in turn clogs the surface of the anode, thereby reducing ion conduction and the dynamic performance of the battery. By placing the first inorganic particles between the polyacrylate particles, the compressive modulus is improved, ensuring that the dynamic performance of the separator and the anode is not affected by the composite particles, thereby improving the dynamic performance of the battery. The composite particles also form protrusions on the substrate or coating surface, and the separator contacts the electrode plates through these protrusions. On the one hand, during the winding process, the protrusions provide an appropriate space to release stress, prevent electrode plate fractures, and improve safety; on the other hand, they leave gaps between the separator and the electrode plates, which are favorable for the flow and infiltration of the electrolyte, and improve the dynamic performance of the battery core.The cooperation of the above conditions ensures that there is adequate adhesion between the separator and the electrode plates, thereby improving the dynamic performance of the battery; and when the battery experiences thermal runaway and generates high temperatures, the protrusions form a large-area adhesive film structure that reduces or blocks ion transmission channels and extends the heat dissipation of the battery, thereby effectively improving the cycle performance and safety performance at high temperatures of the battery.

[0059] The present inventors have conducted extensive research and discovered that the separator of the present application can further improve the performance of the battery when it satisfies the above conditions and, moreover, selectively satisfies one or more of the following conditions:

[0060] In some embodiments, the separator has a compressive modulus of a MPa, the content of the first inorganic particles in the composite particles is b wt%, and a / b is 1.1-60, such as 1.1-59, 1.5-55, 2-55, 5-52, 7-50, 10-48, 12-45, 15-43, 18-40, 20-42, 22-40, 25-37, 27-35, 30-32, etc. In other embodiments, a / b is 4.7-34.

[0061] In some embodiments, the compressive modulus a MPa of the separator is 60 MPa-90 MPa, such as 65 MPa-90 MPa, 65 MPa-85 MPa, 65 MPa-80 MPa, 70 MPa-80 MPa, 75 MPa-80 MPa, 77 MPa-80 MPa, etc., and the content b wt% of the first inorganic particles in the composite particles is 1 wt%-50 wt%, such as Examples include 1wt%-48wt%, 1wt%-45wt%, 1wt%-40wt%, 1wt%-35wt%, 1wt%-30wt%, 1wt%-25wt%, 1wt%-20wt%, 1wt%-15wt%, 2wt%-15wt%, 3wt%-15wt%, 4wt%-15wt%, 5wt%-15wt%, 7wt%-15wt%, 10wt%-15wt%, 12wt%-15wt%, etc. This allows the content of the first inorganic particles in the composite particles to be controlled within the above content range, which on the one hand prevents adhesion between the polyacrylate particles due to high temperature treatment in the granulation process and improves the ion conduction ability of the separator, and on the other hand allows the separator to have an appropriate compressive elastic modulus and ensures an appropriate force between the separator coating and the positive electrode when the battery module is subjected to force.

[0062] In some embodiments, in the separator of the present application, the composite particles have a Dv50 of 2.5 μm or more, such as 2.5 μm-10 μm, 2.5 μm-8 μm, 2.5 μm-6 μm, 2.5 μm-5 μm, 2.5 μm-4 μm, 2.5 μm-3 μm, etc. Therefore, on the one hand, composite particles satisfying this Dv50 range can provide adequate adhesion between the separator coating and the electrode plate, and on the other hand, are advantageous for forming protrusion structures on the coating surface, thereby improving the dynamic performance of the battery core.

[0063] In some embodiments, in the separator of the present application, referring to Figures 1 and 2, first agglomerates are present between the polyacrylate particles, and the first agglomerates include at least two first inorganic particles. This prevents the composite particles from becoming too flexible, thereby ensuring proper interaction between the composite particles and the electrode plate and between the composite particles and the separator when the battery expands or a relatively large external force is applied, thereby improving the dynamic performance of the battery. On the other hand, it prevents the composite particles from fusing together during the fabrication process and blocking the ion transport channels. Furthermore, when the first agglomerates formed by the first inorganic particulate material are present inside or on the surface of the composite particles, it ensures that the roughly spherical body of the composite particles does not soften and collapse at high temperatures (e.g., ≥ 45°C) and under stresses (≥ 0.4 MPa), thereby ensuring proper interaction between the composite particles and the electrode plate and between the composite particles and the separator substrate. This prevents deterioration of the battery's cycling performance and further improves the dynamic performance of the battery.

[0064] In some embodiments, Dv50 of the first agglomerates is 0.01 μm≦Dv10 of the composite particles, thereby increasing the compressive modulus of the separator.

[0065] In some embodiments, the composite particles in the separator of the present application include first inorganic particles in the form of primary particles. Furthermore, the Dv50 of the first inorganic particles in the form of primary particles is 0.01 μm-1 μm, such as 0.01 μm-0.8 μm, 0.05 μm-1 μm, 0.1 μm-1 μm, 0.2 μm-1 μm, 0.3 μm-1 μm, 0.4 μm-1 μm, 0.5 μm-1 μm, 0.6 μm-1 μm, 0.7 μm-1 μm, 0.8 μm-1 μm, or 0.9 μm-1 μm. Therefore, first inorganic particles satisfying this Dv50 can provide the separator with an appropriate compressive modulus, thereby improving the dynamic performance of the battery. In other embodiments, the Dv50 of the first inorganic particles in the form of primary particles is 0.5 μm-1 μm. This can improve the dynamic performance of the battery.

[0066] It should be noted that primary particles and secondary particles have the meanings known in the art. Primary particles refer to particles that are not in an agglomerated state. Secondary particles refer to particles in an agglomerated state formed by the agglomeration of two or more primary particles. Primary particles and secondary particles can be easily distinguished from each other by scanning electron microscope (SEM) images.

[0067] In some embodiments, in the separator of the present application, the composite particles include second agglomerates, and the second agglomerates include at least two of the polyacrylate particles. This prevents the composite particles from becoming too flexible, thereby ensuring proper interaction between the composite particles and the electrode plate and between the composite particles and the separator substrate when the battery expands or a relatively large external force is applied, thereby improving the battery's dynamic performance. Furthermore, the Dv50 of the second agglomerates is 0.3 μm-5 μm, such as 0.5 μm-5 μm, 0.7 μm-4.5 μm, 1 μm-4 μm, 1.3 μm-3.5 μm, 1.5 μm-3.2 μm, 1.7 μm-3 μm, 2 μm-2.8 μm, 2 μm-2.5 μm, 5 μm-10 μm, 5 μm-9 μm, 5 μm-8 μm, 5 μm-7 μm, or 5 μm-6 μm. In some other embodiments, the Dv50 of the second aggregates is 1 μ m-2μm.

[0068] In some embodiments, in the composite particles of the present application, the polyacrylate particles comprise polyacrylate particles in the form of primary particles and / or polyacrylate particles in the form of secondary particles, wherein the Dv50 of the polyacrylate particles in the form of primary particles is 50 nm-400 nm, e.g., 50 nm-375 nm, 75 nm-375 nm, 100 nm-350 nm, 125 nm-325 nm, 150 nm-300 nm, 175 nm-275 nm, 200 nm-250 nm, 200 nm-225 nm, etc., and in some other embodiments, the Dv50 of the polyacrylate particles in the form of primary particles is 100 nm-200 nm. The Dv50 of the secondary particle form polyacrylate particles is 2 μm-15 μm, for example, 3 μm-15 μm, 4 μm-12 μm, 5 μm-10 μm, 5 μm-8 μm, 5 μm-7 μm, 5 μm-6 μm, etc.

[0069] In some embodiments, referring to Figure 3, the separator coating surface of the present application is formed with protrusions, and the height of each of the protrusions on both sides is 15 µm-60 µm, such as 15 µm-58 µm, 16 µm-56 µm, 18 µm-55 µm, 20 µm-52 µm, 22 µm-40 µm, 25 µm-40 µm, 25 µm-38 µm, 25 µm-36 µm, 28 µm-35 µm, or 30 µm-32 µm. Therefore, protrusions within this height range can provide adequate space between the separator and the electrode plate to release stress, prevent breakage during the electrode plate winding process, and improve safety. On the other hand, they also leave an appropriate gap between the separator and the electrode plate, which is favorable for the flow and infiltration of the electrolyte and improves the dynamic performance of the battery core. Furthermore, the surface of the protrusions has primary aggregates. Thereby, the protrusions can provide suitable adhesion between the separator and the electrode plate, thereby enhancing the dynamic performance of the battery.

[0070] Specifically, a coating is formed on both opposing surfaces of the substrate, and the sum of the heights of the protrusions on the coatings on both sides is the height of the two sides of the protrusion. The test method for the height of the two sides of the protrusion includes the following: Referring to Figure 4, first, the negative electrode plate, separator, and positive electrode plate are sequentially stacked on a battery core and then wound (the outermost layer of the battery core terminates at the convex surface of the positive electrode plate). A CT scanner (ZEISS-1500) is then used to scan a position 15±1 mm below the edge of the negative electrode plate at the bend of the wound battery core. In the obtained CT image, horizontal and oblique (30-45°) sampling is performed, and a line is drawn in the direction of the largest gap. The sampling position for the innermost fold is from the convex surface of the innermost positive electrode plate to the convex surface of the fifth positive electrode plate, and the average value for four folds is taken. From the sixth fold onwards, the sampling position is from the convex surface of the inner positive electrode plate to the convex surface of the outer positive electrode plate, and a value is taken every five folds.

[0071] Average value of gap between 5 inner layers = [CT measurement distance - 4 * thickness of negative electrode plate after cold pressing * (1 + repulsion rate of negative electrode plate) - 4 * thickness of positive electrode plate after cold pressing (1 + repulsion rate of positive electrode plate) - 8 * thickness of separator] / 8, The average gap value after the 6th to 10th layers = [CT measurement distance - 5 * thickness of negative electrode plate after cold pressing * (1 + repulsion rate of negative electrode plate) - 5 * thickness of positive electrode plate after cold pressing (1 + repulsion rate of positive electrode plate) - 10 * thickness of separator] / 10. Here, the repulsion rate of the negative electrode plate = (thickness of the negative electrode plate before being placed in the case - thickness of the negative electrode plate after cold pressing) / thickness of the negative electrode plate after cold pressing, The repulsion rate of the positive electrode plate = (thickness of the positive electrode plate before being placed in the case - thickness of the positive electrode plate after cold pressing) / thickness of the positive electrode plate after cold pressing, The height of the separator protrusions on both sides = (average gap value of the inner 5 layers + average gap value after the inner 6-10 layers) / 2.

[0072] In some embodiments, the adhesive comprises an adhesive polymer and a plasticizer. The combined effect of the adhesive polymer and the plasticizer provides the adhesive with good pressure-sensitive properties, which in turn provides the separator with good pressure-sensitive properties, such that the adhesive strength at a pressure of ≦1 MPa is 0.1 N / m or less, preventing adhesion between the layers of the separator during winding and storage, and enabling obvious adhesion to occur between the electrodes at a pressure of ≧2 MPa. When this separator is used to manufacture battery cores, the electrodes and the separator can be tightly attached at room temperature under appropriate pressure, avoiding misalignment between the electrodes and the separator, which would result in the battery core being discarded, affecting the performance of the battery core, and creating safety risks. Also, the tunnel furnace and second combined process required in the conventional battery core production process can be omitted, further saving production space and time, reducing energy consumption, and significantly increasing the production capacity of battery cores. This improves the shaping, safety, and dynamic performance of the battery cores, as well as the safety and dynamic performance of secondary batteries including this battery core and power consumption devices including this secondary battery.

[0073] In some embodiments, the weight ratio of adhesive polymer to plasticizer in the adhesive may be (4-19):1, such as (4-18):1, (4-15):1, (4-12):1, (4-11):1, (4-10):1, (4-8):1, or (4-6):1. By setting the relative content of plasticizer in the adhesive within this range, it is possible to ensure a relatively strong adhesive force between the electrode plate and the separator without increasing the resistance of the separator or reducing the cycling performance of the secondary battery.

[0074] The plasticizer content can be measured using a Shimadzu thermogravimetric analyzer, model STA449F3. For example, the test method is as follows: Approximately 10 mg of adhesive is taken, its original mass is M0, and it is heated to 200°C, resulting in a mass of M1. The plasticizer content is M0-M1, and the adhesive polymer content is M0-(M0-M1). The test conditions are a temperature range of -100-400°C, a nitrogen gas atmosphere, and a rate of 10°C / min.

[0075] In some embodiments, the adhesive may have a core-shell structure, and both the core and shell of the core-shell structure may comprise an adhesive polymer and a plasticizer, where the weight ratio of the adhesive polymer to the plasticizer in the core structure may be (2-5):1, e.g., (3-4):1, and the weight ratio of the adhesive polymer to the plasticizer in the shell structure may be (6-10):1, e.g., (7-9):1, (7-8):1. The core and shell of the core-shell structure, both composed of an adhesive polymer and a plasticizer, can further improve the pressure-sensitive performance of the pressure adhesive, thereby further enhancing the dynamic performance of the separator. On the other hand, the adhesive contains a plasticizer. Under a certain pressure (e.g., 1 MPa-2 MPa), the plasticizer rapidly migrates between the adhesive polymer and the separator base material, plasticizing the adhesive polymer and extending its molecular chain, generating intermolecular hydrogen bonding with the negative electrode plate's adhesive, such as SBR adhesive or CMC thickener, and the positive electrode plate's adhesive, such as PVDF, thereby enhancing interfacial wetting and reinforcing the riveting effect between the two interfaces. Under pressure of ≥ 2 MPa, the core structure is fractured, releasing the plasticizer in the core, further enhancing the above effects.

[0076] In some embodiments, a portion of the plasticizer is grafted onto the adhesive polymer. For example, at least 5 wt% of the plasticizer, based on the weight of the plasticizer, is grafted onto the adhesive polymer. When a portion of the plasticizer is grafted onto the adhesive polymer, it is possible to prevent the plasticizer from migrating into the electrolyte during cycling, consuming various functional additives in the electrolyte, increasing the separator resistance, and affecting the dynamic performance of the battery core. Here, when at least 5 wt% of the plasticizer is grafted onto the backbone of the adhesive polymer, the separator and the electrode plate form a "disconnected yet connected" interaction, further improving the durability of the room-temperature adhesion and reducing rebound, while also ensuring that too much plasticizer does not migrate into the electrolyte during cycling and affect the performance of the battery core.

[0077] Here, the grafting rate of the plasticizer in the adhesive polymer can be detected by infrared testing method, specifically, by testing the adhesive polymer, the plasticizer, and the adhesive respectively to obtain their Fourier infrared spectra, and -1 -1700cm -1 A peak different from that of the adhesive polymer and the plasticizer alone appears at the position of , and this peak represents the grafted plasticizer. The area under the peak represents the amount of grafted plasticizer, and the graft rate of the plasticizer can be calculated based on this.

[0078] In some embodiments, the adhesive polymer may have an average particle size of 0.5 μm-3.0 μm, e.g., 0.8 μm-2.8 μm, 1 μm-2.5 μm, 1.2 μm-2.3 μm, 1.5 μm-2 μm, or 1.8 μm-2 μm. Adhesive polymers meeting the average particle size specification of the present application contribute to uniform distribution on the composite particles and contribute to adhesion to the electrode plate at a constant pressure. In some embodiments, the adhesive polymer may have an average particle size of 0.8 μm-2 μm.

[0079] Here, the average particle size of the adhesive polymer can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with standard GB / T 19077.1-2016.

[0080] In some embodiments, the adhesive may have a DSC melting point of −50° C. to 100° C., for example, −45° C. to 95° C., −40° C. to 90° C., −35° C. to 85° C., −30° C. to 80° C., −25° C. to 75° C., −20° C. to 70° C., −15° C. to 65° C., −10° C. to 60° C., −5° C. to 55° C., 0° C. to 50° C., 5° C. to 45° C., 10° C. to 40° C., 15° C. to 35° C., 20° C. to 30° C., or 25° C. to 30° C. An adhesive that satisfies the above DSC melting point range can ensure adhesive strength at room temperature and avoid the adhesive strength at 1 MPa being too high, which would lead to adhesion during winding of the separator, and avoid the adhesive strength at 2 MPa at room temperature being too low, which would weaken the bond between the separator and the electrode plates and cause disadvantages to shaping of the battery core.

[0081] In some examples, the DSC melting point has a meaning known in the art and can be measured using instruments and methods known in the art, such as a DSC melting point tester with the model number DSC 200F3 manufactured by NETZSC GmbH, Germany. In a specific example, the test method is as follows: approximately 10 mg of sample is taken for testing. The test conditions are set as follows: temperature range: -100-200°C, nitrogen gas atmosphere, 10°C / min. When the first heating step is selected, the temperature corresponding to the absorption peak is the corresponding DSC melting point.

[0082] In some embodiments, the adhesive polymer comprises a copolymer formed by the reaction of at least one of the following first monomers, at least one of the following second monomers, at least one of the following third monomers with at least one reactive dispersant: First monomers: their melting points are generally higher than 80°C and include acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, and acrylonitrile; Second monomer: its melting point generally does not exceed 80°C, and is selected from the group consisting of C4-C22 alkyl acrylate, isobutyl acrylate, isooctyl acrylate, tert-butyl acrylate, 2-ethylhexyl (isooctyl) acrylate, cyclohexyl acrylate, ethyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate Lu, Me Acrylic Acid Lu Including, Third monomer: 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, gamma -Methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, methacrylic acid, ethyl acetoacetate, divinylbenzene, epoxy resin with an epoxy value of 0.35-0.50, including divinylbenzene; Reactive dispersants include polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, and polyvinyl alcohol. Optionally, the degree of alcoholysis of these reactive dispersants is ≥85% and the average degree of polymerization is 400-2000, preferably ≥88% and the average degree of polymerization is 500-1600.

[0083] Therefore, the adhesive polymer of this composition has suitable swelling, pressure sensitivity and adhesive properties, as well as suitable elastic modulus, thereby providing the battery core with excellent shaping effect, dynamic performance and safety performance.

[0084] It should be noted that in this application, the term "degree of alcoholysis" refers to the percentage of hydroxyl groups in the product obtained after alcoholysis that occupy the original groups, and the unit is mole fraction %. For example, if the original groups (ester groups) are 100 and the hydroxyl groups after alcoholysis are 60, the degree of alcoholysis is 60%.

[0085] It should be noted that in this application, the term "average degree of polymerization" refers to the fact that a polymer is composed of similar polymer molecules with different degrees of polymerization, and the degree of polymerization is a statistical average. There are two most commonly used ways to express the average degree of polymerization. The degree of polymerization obtained by averaging the number of molecules is called the number-average degree of polymerization, and the degree of polymerization obtained by averaging the weight is called the weight-average degree of polymerization. In this application, the "average degree of polymerization" refers to the number-average degree of polymerization.

[0086] In some embodiments, the plasticizer may include at least one of a glycerol C4-C10 alkyl di- or mono-ether, a glycerol C4-C10 carboxylic acid mono- or di-ester, a propylene glycol C4-C10 alkyl mono-ether, and glycerol.

[0087] In some examples, the adhesive may be synthesized according to the following synthesis method, which includes the following steps:

[0088] Step 1: To a solvent (e.g., deionized water), 0.1% by weight-1% by weight (based on the total weight of the reactive monomer mixture (including the first monomer, the second monomer, the third monomer, and the reactive dispersant), the auxiliary (including the emulsifier, the stabilizer, and the aqueous initiator) and the plasticizer added during adhesive synthesis; the same applies below) of an emulsifier (e.g., allyl sulfonate) and 2% by weight-3% by weight of an oligomer (e.g., octadecyl methacrylate) having a number average molecular weight of ≦1000 and a melting point of 0°C-30°C are sequentially added, and the rotation speed of the homogenizer is controlled to 8000 r / min-12000 r / min, for example 10000 r / min, to disperse the mixture. The dispersion time can be 20 min-60 min, for example 50 min, and the dispersion reaction temperature is 20°C-40°C, for example 25°C, to obtain a first mixture.

[0089] Step 2: Add 1%-4% by weight of a stabilizer to the first mixture, such as at least one of polyethylene oxide, allyl polyether sulfate, methylene succinic acid (itaconic acid), styrene sulfonic acid, sodium vinyl sulfonate, and sodium nanocellulose, and mix by controlling the rotation speed of the homogenizer to 6000 r / min-8000 r / min, for example 6500 r / min, for a time of 20 min-60 min, for example 30 min, at a mixing reaction temperature of 20°C-60°C, for example 45°C, to obtain a second mixture.

[0090] Step 3: Add 0.05%-0.5% by weight of an aqueous initiator to the second mixture, such as sodium bicarbonate, benzoyl peroxide, lauroyl peroxide, cumene hydrogen peroxide, t-butyl hydrogen peroxide, di-t-butyl peroxide, dicumene peroxide, t-butyl peroxybenzoate, t-butyl t-valerate peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxide, dicyclohexyl peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, azobisisobutyronitrile, and azobisisoheptonitrile. The homogenizer speed is controlled to 8000 r / min-12000 r / min, e.g., 8000 r / min, and the mixing time is 20-60 min, e.g., 30 min. The reaction temperature is 60°C-80°C, e.g., 72°C, to obtain a third mixture.

[0091] Step 4: Under the condition of a homogenizer rotation speed of 100 r / min-1000 r / min, for example 400 r / min, a 35%-45% by weight reaction monomer mixture is gradually and uniformly added dropwise to the third mixture (controlled so that the addition is completed exactly in 60 minutes), and the reaction time is 80 min-100 min, for example 80 min, to obtain a fourth mixture.

[0092] Step 5: Continue reacting the fourth mixture under conditions where the reaction temperature is 80°C-90°C, for example 84°C, the homogenizer rotation speed is 12000 r / min-18000 r / min, for example 15000 r / min, and the reaction time is 120 min-240 min, for example 180 min, to obtain a fifth mixture.

[0093] Step 6: Add 10%-20% by weight of a plasticizer, such as glycerol, to the fifth mixture, control the reaction temperature to 80°C-90°C, for example, 84°C, control the homogenizer rotation speed to 12000 r / min-18000 r / min, for example, 15000 r / min, and the reaction time to 120 min-240 min, for example, 180 min, to obtain a sixth mixture.

[0094] Step 7: Add 0.05%-0.5% by weight of an aqueous initiator, such as ammonium persulfate-sodium bicarbonate, to the sixth mixture. Control the homogenizer speed at 8000-12000 r / min, for example, 8000 r / min, for 20-60 minutes, for example, 30 minutes. The reaction temperature is 60°C-80°C, for example, 72°C, to obtain a seventh mixture.

[0095] Step 8: Under the condition of a homogenizer rotation speed of 100 r / min-1000 r / min, for example 400 r / min, gradually and uniformly add 30%-40% by weight of the reaction monomer mixture to the seventh mixture (controlling the addition so that it is completed exactly in 60 minutes), and the reaction time is 100 min-160 min, for example 120 min, to obtain an eighth mixture.

[0096] Step 9: Add 5%-20% by weight of a plasticizer, such as glycerol, to the eighth mixture, control the reaction temperature to 80°C-90°C, for example, 84°C, and use a homogenizer with a rotation speed of 12000 r / min-18000 r / min, for example, 15000 r / min, for a time of 120 min-240 min, for example, 180 min, to obtain a ninth mixture.

[0097] Step 10: Lower the temperature of the ninth mixture to below 50°C, and filter to remove the material, thereby obtaining a core-shell adhesive. Those skilled in the art can synthesize non-core-shell adhesives by referring to the above method (omitting steps 7 to 9 and changing the mass fractions of the plasticizer and reactive monomer mixture accordingly).

[0098] In some embodiments, the coating includes composite particles, second inorganic particles, and an adhesive. The adhesive includes a linear copolymer having hydroxyl groups and carboxylate salts. The carboxylate salt moieties in the linear copolymer can bond with the second inorganic particles and the composite particles through chemical forces (e.g., ionic bonds, hydrogen bonds, etc.), improving the heat resistance of the separator and improving the dynamic performance of the battery core. The hydroxyl groups in the linear copolymer also improve adhesion between the coating and the substrate, preventing peeling. Specifically, the hydroxyl groups in the linear copolymer in the adhesive form hydrogen bonds between the composite particles and the second inorganic particles, while the nitrogen and oxygen atoms in the linear copolymer form hydrogen bonds between the composite particles and the second inorganic particles, etc. The carboxylate salt moieties (including lithium ions, sodium ions, etc.) in the linear copolymer form ionic bonds between the composite particles and the second inorganic particles, etc. By selecting appropriate particle materials and adhesives, the separator of the present application achieves beneficial effects such as heat resistance, resistance to puncture by foreign objects, good electrolyte penetration, and low resistance. Furthermore, such separators can be used in batteries to improve the safety and cycling performance of the batteries.

[0099] In some embodiments, when the coating includes composite particles, second inorganic particles, and an adhesive, the adhesive in the separator of the present application may include a linear copolymer containing hydroxyl groups, carboxylate salts, amide groups, and epoxy groups. The epoxy groups and amide groups contained in the linear copolymer can further improve the safety performance of the separator. Specifically, the amide groups can form hydrogen bonds between the composite particles and the second inorganic particles, and the nitrogen and oxygen atoms contained in the linear copolymer can form hydrogen bonds with the hydroxyl groups, amide groups, carboxyl groups, or pyrrolidone groups of the second inorganic particles and the composite particles, thereby improving the heat resistance of the separator.

[0100] In addition, the hydroxyl groups or amide groups contained in the adhesive undergo a nucleophilic substitution reaction with the ester groups, carboxyl groups, sulfonylamide groups, or pyrrolidone groups of the composite particles, and also undergo a nucleophilic addition reaction between the epoxy groups in the composite particles and the carboxyl groups or amide groups contained in the adhesive.

[0101] In some embodiments, the carboxylate in the adhesive may be a lithium carboxylate. The lithium carboxylate can effectively form a relatively strong ionic bond between the composite particles and the second inorganic particles, further enhancing the temperature resistance of the entire coating, particularly at temperatures above 130°C. The separator does not shrink, and when a large amount of heat is generated by the needle penetration, the separator does not shrink and cause large-area contact between the positive and negative electrodes, significantly increasing the needle penetration depth. This action penetrates the coating, the base film, and the coating interface, which has a very strong polarity. The presence of lithium ions accelerates electrolyte infiltration and diffusion, improving the dynamic performance of the battery core.

[0102] In some embodiments, when the separator coating includes composite particles, second inorganic particles, and an adhesive, the linear copolymer in the separator of the present application includes a polymerization product of various monomers such as: (1) a first class of monomers, said first class of monomers comprising at least one of acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, and acrylonitrile; optionally, said first class of monomers comprising at least one of styrene, methacrylic acid, acrylamide, acrylic acid, and acrylonitrile; (2) A second type of monomer, the second type of monomer including at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, cyclohexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-hexyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, ethylene urea ethyl methacrylate, acrylic methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, and trifluoroethyl methacrylate. See, select Alternatively, the second type of monomer comprises at least one of n-butyl acrylate and n-hexyl methacrylate; (3) a third type of monomer, the third type of monomer comprising at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl (meth)acrylamide, diacetoneacrylamide, ethyl methacrylate acetoacetate, divinylbenzene, and an epoxy resin having an epoxy value of 0.35 to 0.50; optionally, the third type of monomer comprises at least one of 2-hydroxyethyl methacrylate, an epoxy resin having an epoxy value of 0.35 to 0.50, and divinylbenzene; (4) A fourth type of monomer, the fourth type of monomer comprising at least one of polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol and polyvinyl alcohol, optionally the fourth type of monomer being polyvinyl alcohol, wherein the degree of alcoholysis of the fourth type of monomer is ≧85% and the average degree of polymerization is 400 to 2000, optionally the degree of alcoholysis of the fourth type of monomer is ≧88% and the average degree of polymerization is 500 to 1600.

[0103] As a result, the linear copolymer containing the above monomer allows the adhesive to have good wettability with the substrate, thereby increasing the yield rate of substrate application and improving coating density. More importantly, it improves the adhesion between the second inorganic particles and composite particles and the substrate, significantly improving the heat shrinkage performance of the separator, thereby improving the safety performance of the battery core. It can also generate chemical reactions with the particle materials in the coating, thereby creating an appropriate dense structure and further improving the safety of the separator. This three-dimensional interaction also penetrates the transmission channels of lithium ions, increasing the ionic electrical conductivity of the separator and improving the dynamic performance of the battery core.

[0104] In some embodiments, when the coating of the separator of the present application includes composite particles, second inorganic particles, and an adhesive, after polymerizing the first, second, third, and fourth monomers of the linear copolymer, a pH adjuster must be added to adjust the pH of the system to 5-7, and the pH adjuster may include at least one of lithium hydride, calcium hydride, sodium hydride, and aqueous ammonia. In other embodiments, the pH adjuster includes lithium hydride. Adjusting the pH of the system by adding a pH adjuster after polymerizing the monomers favors the dispersion of the second inorganic particles in the adhesive, thereby further improving the coating interface and improving the cycle performance and safety performance of the battery core. In particular, in some embodiments, the pH adjuster is lithium hydride. Without being bound by any theory, the inventors discovered that using lithium hydride as a pH adjuster can adjust the pH while simultaneously providing lithium ions that increase the electrical conductivity and glass transition temperature (Tg) of the resulting separator, thereby further improving the cycle performance and safety performance of the separator.

[0105] In some embodiments, in the separator of the present application, when the coating includes composite particles, second inorganic particles, and an adhesive, the first type of monomer occupies 60% to 85% by weight, optionally 70% to 80% by weight, and / or the second type of monomer occupies 1% to 10% by weight, optionally 5% to 10% by weight, and / or the third type of monomer occupies 1% to 10% by weight, optionally 1% to 5% by weight, and / or the fourth type of monomer occupies 1% to 20% by weight, optionally 10% to 15% by weight, calculated based on the total weight of all monomers included in the linear copolymer.

[0106] In some embodiments, the occupancy of the first monomer may be within a range defined by any two of the following combined values: 60 wt%, 62 wt%, 64 wt%, 66 wt%, 68 wt%, 70 wt%, 72 wt%, 74 wt%, 76 wt%, 78 wt%, 80 wt%, 82 wt%, or 85 wt%.

[0107] In some embodiments, the second monomer occupancy may be within a range formed by combining any two of the following values: 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, or 10 wt %.

[0108] In some embodiments, the third monomer percentage may be within a range defined by any two of the following values: 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, or 10 wt %.

[0109] In some embodiments, the fourth monomer occupancy may be within a range formed by combining any two of the following values: 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%.

[0110] The content of each monomer can be controlled within the above range to obtain a separator having the above-mentioned second inorganic particles of the present application. In some embodiments, in the separator of the present application, when the separator coating contains second inorganic particles, the linear copolymer is A. 30% styrene-15% methacrylic acid-10% acrylamide-15% acrylic acid-5% acrylonitrile-10% n-butyl acrylate-2% 2-hydroxyethyl methacrylate-1% E44 epoxy resin-12% polyvinyl alcohol copolymer; B. 35% styrene-15% methacrylic acid-10% acrylamide-15% acrylic acid-5% acrylonitrile-5% n-butyl acrylate-2% 2-hydroxyethyl methacrylate-1% E44 epoxy resin-12% polyvinyl alcohol copolymer; C. 30% styrene-15% methacrylic acid-10% acrylamide-15% acrylic acid-5% acrylonitrile-10% n-butyl acrylate-3% 2-hydroxyethyl methacrylate-12% polyvinyl alcohol copolymer; D. 30% styrene-15% methacrylic acid-15% acrylamide-15% acrylic acid-5% acrylonitrile-5% n-butyl acrylate-2% 2-hydroxyethyl methacrylate-1% E44 epoxy resin-12% polyvinyl alcohol copolymer; E. 40% styrene-15% acrylamide-15% acrylic acid-10% n-butyl acrylate-5% n-hexyl methacrylate-2% 2-hydroxyethyl methacrylate-1% E44 epoxy resin-12% polyvinyl alcohol copolymer; F. 35% styrene-15% methacrylic acid-10% acrylamide-15% acrylic acid-5% acrylonitrile-5% n-butyl acrylate-2% divinylbenzene-1% E44 epoxy resin-12% polyvinyl alcohol copolymer; Here, the average epoxy value of the E44 epoxy resin is 0.44, the degree of alcoholysis of the polyvinyl alcohol is 88%, and the degree of polymerization is 1000, and the percentages are weight percentages calculated based on the total weight of all the monomers.

[0111] In some embodiments, in the separator of the present application, when the coating includes composite particles, second inorganic particles, and an adhesive, the weight average molecular weight of the linear copolymer is 1×10 3 g / mol to 200 × 10 3 g / mol, and optionally 2×10 3 g / mol to 80×10 3In some embodiments, the weight average molecular weight of the linear copolymer is less than 1×10 3 g / mol, 5 × 10 3 g / mol, 10 × 10 3 g / mol, 20×10 3 g / mol, 30 × 10 3 g / mol, 40 × 10 3 g / mol, 50 × 10 3 g / mol, 60 × 10 3 g / mol, 70 × 10 3 g / mol, 80 × 10 3 g / mol, 100 × 10 3 g / mol, 150 × 10 3 g / mol or 200 × 10 3 The weight-average molecular weight of the linear copolymer may be within a range combining any two values ​​of g / mol. The weight-average molecular weight of the linear copolymer is controlled within the above range so that it can generate an appropriate chemical reaction with the particulate material and an appropriate wetting action with the substrate.

[0112] In some examples, the weight average molecular weight (Mw) of the linear copolymer is measured by using a Nippon Tosoh Corporation HLC-8320 GPC gel permeation chromatography (for SuperMultipore HZ series semi-micro SEC columns, the standard is polystyrene).

[0113] In some embodiments, in the separator of the present application, the Dv50 of the composite particles is greater than the Dv50 of the second inorganic particles, which not only can provide adequate adhesion between the separator and the electrode plate, but also is advantageous for forming protrusions on the coating surface, thereby improving the battery safety and the dynamic performance of the battery core.

[0114] In some embodiments, the second inorganic particles may include one or more of boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon dioxide (SiO2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (YO3), nickel oxide (NiO), cerium oxide (CeO2), zirconium titanate (SrTiO3), barium titanate (BaTiO3), and magnesium fluoride (MgF2). This type of second inorganic particles can effectively inhibit the thermal shrinkage of the substrate, thereby improving the high-temperature resistance of the separator. For example, Second The inorganic particles may include one or more of boehmite (γ-AlOOH), aluminum oxide (Al2O3).

[0115] In some embodiments, in the separator of the present application, the Dv50 of the second inorganic particles is 0.5 μm-2 μm, such as 0.5 μm-1.8 μm, 1 μm-2 μm, 1 μm-1.8 μm, 1.2 μm-1.8 μm, 1.4 μm-1.6 μm, etc. The second inorganic particles have a good effect of inhibiting the thermal shrinkage of the substrate, thereby improving the thermal stability of the separator; second inorganic particles satisfying this particle size range can be uniformly dispersed in the separator coating, thereby improving the thermal stability of the separator; and second inorganic particles within this particle size range are advantageous for obtaining a relatively small coating thickness, which can further improve the volumetric energy density of the battery while providing good cycle performance and safety performance of the battery.

[0116] In some embodiments, in the separator of the present application, the mass ratio of the composite particles to the second inorganic particles is (5-30):(50-70), for example, (5-30):(52-68), (5-30):(55-65), (5-30):(57-62), (5-30):(60-62), (7-28):(50-70), (10-25):(50-70), (12-22):(50-70), (15-20):(50-70), or (15-18):(50-70), which, on the one hand, can optimize the adhesive strength between the separator and the electrode plate, improving the dynamic performance of the battery, and on the other hand, can improve the high temperature resistance and ionic conductivity of the separator, thereby effectively improving the cycle performance and high temperature safety performance of the battery.

[0117] In some embodiments, the mass ratio of the composite particles to the solid content of the adhesive in the separator of the present application is (80-90):(5-20), such as (80-90):(6-20), (80-90):(7-18), (80-90):(8-15), (80-90):(9-11), (80-90):10, (81-89):(5-20), (82-88):(5-20), (83-87):(5-20), (84-86):(5-20), or 85:(5-20). The inventors discovered that mixing the composite particles and adhesive in the coating according to this ratio can simultaneously improve battery safety performance and energy density, while also optimizing adhesion between the separator and the electrode plates, thereby improving the dynamic performance of the battery. In some other embodiments, in the separator of the present application, the mass ratio of the composite particles to the adhesive is (85-90):(8-15).

[0118] In some embodiments, the separator coating of the present application may further include organic particles, i.e., the separator coating may include composite particles, an adhesive, and organic particles, or the separator coating may include composite particles, an adhesive, organic particles, and second inorganic particles, wherein the organic particles include at least one of polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylic acid-based monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylate-based monomer units, and particles of modified compounds of the above homopolymers or copolymers, and the composite particles and the organic particles form the protrusions on the coating surface, thereby improving the cycle performance and safety of the battery.

[0119] The coating on the separator in FIG. 5 includes composite particles, organic particles, an adhesive, and second inorganic particles, and the composite particles and organic particles form protruding structures on the coating surface.

[0120] In some embodiments, the organic particles of the separator coating of the present application form third agglomerates, wherein the Dv50 of the third agglomerates is 5 μm-30 μm, e.g., 5 μm-28 μm, 5 μm-25 μm, 5 μm-22 μm, 5 μm-20 μm. m、5 μm-18μm, 5μm-15μm, 5μm-12μm, 5μm-10μm, 5μm-8μm, 5μm-6μm, etc.

[0121] In some embodiments, the third aggregates include organic particles in the form of primary particles, with gaps between adjacent organic particles. These gaps may serve as ion transmission channels, thereby improving the ionic conductivity of the separator. In some embodiments, the organic particles in the form of primary particles have a Dv50 of 50-400 nm, e.g., 50-375 nm, 75-375 nm, 100-350 nm, 125-325 nm, 150-300 nm, 175-275 nm, 200-250 nm, or 200-225 nm. In other embodiments, the organic particles in the form of primary particles have a Dv50 of 100-200 nm.

[0122] In this application, Dv50 refers to the particle size corresponding to the cumulative volume distribution rate reaching 50%, and Dv10 refers to the particle size corresponding to the cumulative volume distribution rate reaching 10%. In this application, the Dv10 of the composite particles, the Dv50 of the composite particles, the Dv50 of the secondary inorganic particles, and the Dv50 of the primary organic particles may all be measured using laser diffraction particle size analysis. For example, they may be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with GB / T 19077-2016. The Dv50 of the first inorganic particles in primary particle form, the Dv50 of the polyacrylate particles in primary particle form, and the Dv50 of the polyacrylate particles in secondary particle form are obtained by statistical analysis from a separator SEM image, for example, by taking a separator SEM image at a magnification of 10Kx, using five parallel samples for each sample, using 10 positions for each parallel sample, and selecting 20 points for each position, and finally taking the average to obtain the corresponding particle size. The Dv50 of the first agglomerates, the Dv50 of the second agglomerates, and the Dv50 of the third agglomerates are obtained by statistical analysis from a CP image of the separator, for example, by taking a separator CP image at a magnification of 5Kx, using five parallel samples for each sample, using 10 positions for each parallel sample, and selecting 20 points for each position, and finally taking the average to obtain the corresponding particle size.

[0123] In some embodiments, the weight ratio of the composite particles to the organic particles is (20-90):(0-70), for example, the weight ratio of the composite particles to the organic particles is (20-90):(5-65), (20-90):(10-60), (20-90):(20-50), (20-90):(30-40), (30-80):(0-70), (40-70):(0-70), (50-60):(0-70), (30-80):(5-65), (40-65):(10-55), (45-60):(20-45), or (55-60):(30-45), which can improve the infiltration and distribution uniformity of the electrolyte, improve the high-temperature storage performance of the battery, and enhance the battery safety and cycle performance. In some other embodiments, the mass ratio of the composite particles to the organic particles is (45-90):(0-45), which can improve the battery safety and cycle performance.

[0124] As shown in FIG. 6, the separator includes a substrate and a coating, the coating includes composite particles, organic particles, and an adhesive, the composite particles and the organic particles are connected to the substrate via the adhesive, and the composite particles form protrusions on the surface of the coating together with the organic particles.

[0125] As shown in FIG. 7, the separator includes a substrate and a coating, and the coating includes composite particles, organic particles, second inorganic particles, and an adhesive. The composite particles, organic particles, and second inorganic particles are connected to the substrate via the adhesive, and the composite particles form protrusions on the surface of the coating together with the organic particles.

[0126] In some embodiments, when the coating comprises composite particles and an adhesive, the single-sided coating weight on the separator per unit area is 0.2 g / m 2 -2g / m 2 For example, 0.5 g / m 2 -1.8g / m 2 , 0.7g / m 2 -1.5g / m 2 , 1g / m 2 -1.5g / m 2, 1g / m 2 -1.2g / m 2 When the coating includes composite particles, second inorganic particles, and an adhesive, the coating weight on one side of the separator per unit area is 1.5 g / m 2 -4g / m 2 For example, 2 g / m 2 -4g / m 2 , 2g / m 2 -3.5g / m 2 , 2g / m 2 -3g / m 2 , 2g / m 2 -2.5g / m 2 When the single-sided coating weight on the separator per unit area is within a certain range, the energy density of the battery can be further improved while ensuring the cycle performance and safety performance of the battery.

[0127] In some embodiments, the coating may further include other organic compounds, such as polymers for improving heat resistance, dispersants, wetting agents, and other types of adhesives. The other organic compounds are all non-particulate substances in the coating. The present application does not particularly limit the type of the other organic compounds, and any known material with good improving properties may be selected and used.

[0128] In this application, the substrate is a porous membrane material with good chemical and mechanical stability. In some embodiments, the substrate may be a single-layer membrane material or a multi-layer composite membrane material. When the substrate is a multi-layer composite membrane material, the materials of each layer may be the same or different.

[0129] In some embodiments, the substrate of the separator of the present application may be a porous membrane or a porous nonwoven mesh comprising one or more of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cycloolefin copolymer, polyphenylene sulfide, and polyethylene naphthalene. In other embodiments, the substrate is a porous membrane or a porous nonwoven mesh comprising polyethylene and / or polypropylene. The separator is manufactured by selecting the above substrate, which is advantageous for bonding with the coating via an adhesive, and forms a separator that is appropriately dense, porous, and capable of conducting lithium ions.

[0130] In some embodiments, the substrate of the separator of the present application has a porosity of 10%-95%, e.g., 15%-90%, 20%-85%, 25%-80%, 30%-75%, 35%-70%, 40%-65%, 45%-60%, or 50%-55%. In other embodiments, the substrate of the separator of the present application has a porosity of 35%-45%. This improves the ionic conductivity of the separator while reducing the probability of contact between the positive and negative electrodes. In some embodiments, the substrate of the separator of the present application has a pore diameter of 0.1 μm-50 μm, e.g., 0.5 μm-50 μm, 1 μm-45 μm, 5 μm-40 μm, 10 μm-35 μm, 15 μm-30 μm, or 20 μm-25 μm. In some other embodiments, in the separator of the present application, the substrate has a pore diameter of 0.1 μm-5 μm. Selecting a substrate with this pore structure allows the separator to have good ion conductivity, reduce the probability of direct contact between the positive and negative electrodes, and further improve the dynamics and safety of the battery core.

[0131] In some embodiments, the thickness of the substrate is ≦10 μm, for example, the thickness of the substrate may be 5 μm-10 μm, 5 μm-9 μm, or 7 μm-10 μm. When the thickness of the substrate is controlled within a predetermined range, the battery energy density can be further improved while ensuring the battery cycle performance and safety performance.

[0132] In some embodiments of the present application, the peel strength of the coating is 40 N / m or more, and after leaving the separator unclamped in a 150°C environment for 1 hour, the thermal shrinkage in both the machine direction (MD) and the cross direction (TD) is 5% or less, the 200°C heat gun failure size is 0, the adhesive strength between the separator and the electrode plate is 1.0 N / m or more, and the separator resistance at 25°C is 2 ohms or less.

[0133] According to some embodiments, the material types of the polyacrylate particles, organic particles, and adhesives can be tested using equipment and methods known in the art. For example, the infrared absorption spectrum of the material can be tested to determine the characteristic peaks contained therein, thereby determining the material type. Specifically, infrared absorption spectrum analysis can be performed on the organic particles using equipment and methods known in the art. For example, an infrared spectrometer, such as an IS10 Fourier transform infrared spectrometer from Nicolet, USA, can be used, and testing can be performed in accordance with GB / T 6040-2002, General Principles for Infrared Absorption Spectroscopy.

[0134] A second aspect of the present application further provides a method for manufacturing a separator, the method comprising: (1) providing a substrate; (2) forming a coating comprising composite particles and an adhesive on at least a portion of the surface of the substrate, wherein the composite particles form protrusions on the coating surface, and the composite particles comprise polyacrylate particles and first inorganic particles, with the first inorganic particles between at least two of the polyacrylate particles.

[0135] Specifically, the substrate, the composite particles, the first inorganic particles and the adhesive are the same as described above and will not be further described here.

[0136] In some embodiments, the separator comprises a substrate and a coating, the coating being disposed on only one surface of the substrate.

[0137] In some embodiments, the separator comprises a substrate and a coating, the coating being simultaneously applied to two surfaces of the substrate.

[0138] In some embodiments, step (2) can be performed by employing the following steps: (2-1) providing a coating slurry, the coating slurry including composite particles and an adhesive; and (2-2) applying the coating slurry onto at least one side of the substrate and drying the coating slurry to obtain the separator.

[0139] In some embodiments, in step (2-1), the solvent in the coating slurry may be water, for example, deionized water.

[0140] In some embodiments, in step (2-1), the coating slurry may further include other organic compounds, such as a polymer for improving heat resistance, a dispersant, a wetting agent, or an emulsion-like adhesive, wherein the other organic compounds are all non-particulate in the dried coating.

[0141] In some embodiments, in step (2-1), the solid content of the coating slurry may be controlled to 10%-20%, for example, 12%-15%, calculated based on weight. When the solid content of the coating slurry is within the above range, the yield rate of the coating production and the coating adhesion performance can be improved.

[0142] In some embodiments, in step (2-1), the coating slurry may further include organic particles, and the organic particles include at least one of polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylic acid-based monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylate-based monomer units, and particles of modified compounds of the above-mentioned homopolymers or copolymers.

[0143] In some embodiments, in step (2-1), the coating slurry may further comprise second inorganic particles, and the second inorganic particles may be selected from the group consisting of boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon dioxide (SiO2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (YO3), nickel oxide (NiO), cerium oxide (CeO2), zirconium titanate ...yttrium oxide (YO3), nickel oxide (NiO), yttrium oxide (YO3), nickel oxide (NiO), yttrium oxide (YO3), nickel oxide (NiO), yttrium oxide (Y ZrTiO For example, the inorganic particles may include one or more of boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium titanate (BaTiO3), and magnesium fluoride (MgF2).

[0144] In some embodiments, in step (2-1), when the coating slurry further comprises second inorganic particles, the solid content of the coating slurry may be controlled to 28%-45%, for example, 30%-38%, calculated by weight. When the solid content of the coating slurry is within the above range, it can effectively reduce the coating film surface problem and the probability of uneven coating, thereby further improving the cycle performance and safety performance of the battery.

[0145] In some embodiments, in step (2-2), the coating is carried out using a coating machine.

[0146] In the embodiments of the present application, the model number of the applicator is not particularly limited, and any commercially available applicator may be used.

[0147] In some embodiments, in step (2-2), the coating may be performed by a process such as transfer coating, spin spraying, or dip coating, for example, the coating is performed by transfer coating.

[0148] In some embodiments, the applicator includes an intaglio roller, which is used to transfer the coating slurry onto the substrate.

[0149] In some embodiments, when the coating slurry may further contain second inorganic particles, the ruling of the intaglio roller may be 100 LPI to 300 LPI, for example 125 LPI to 190 LPI (LPI is lines per inch). When the ruling of the intaglio roller is within the above range, it contributes to controlling the number of composite particles and polyvinylidene fluoride particles, thereby further improving the cycling performance and safety performance of the separator.

[0150] In some embodiments, when the coating slurry further comprises second inorganic particles, the coating speed in step (2-2) may be controlled to 30 m / min-90 m / min, for example, 50 m / min-70 m / min, which can effectively reduce coating surface problems and the probability of non-uniform coating, thereby further improving the cycle performance and safety of the battery.

[0151] In some embodiments, when the coating slurry may further contain second inorganic particles, in step (2-2), the linear speed ratio of the coating may be controlled to 0.8-2.5, for example, 0.8-1.5, 1.0-1.5.

[0152] In some embodiments, when the coating slurry may further include second inorganic particles, in step (2-2), the drying temperature may be 40°C-70°C, for example, 50°C-60°C.

[0153] In some embodiments, when the coating slurry may further include second inorganic particles, in step (2-2), the drying time may be 10 s-120 s, for example, 20 s-80 s, 20 s-40 s.

[0154] By controlling each of the above process parameters within a predetermined range, the performance of the separator of the present application can be further improved. Those skilled in the art can selectively adjust and control one or several of the above process parameters according to the actual production situation.

[0155] The above-mentioned substrate, composite particles, second organic particles, adhesive and organic particles can all be commercially available.

[0156] A third aspect of the present application provides a battery, which includes the separator of the first aspect or a separator manufactured by employing the second aspect.

[0157] The battery refers to a battery that can be continuously used by activating the active material through charging after discharge.

[0158] Generally, a battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging of the battery, active ions are absorbed and released back and forth between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to provide isolation. The electrolyte conducts ions between the positive and negative electrodes.

[0159] [Positive electrode plate] In a battery, the positive electrode plate generally includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0160] The positive electrode current collector may be a conventional metal foil sheet or a composite current collector (a metal material may be deposited on a polymer substrate to form a composite current collector). For example, the positive electrode current collector may be aluminum foil.

[0161] The specific type of the positive electrode active material is not limited, and any active material known in the art that can be used for a battery positive electrode may be used, and those skilled in the art can select it according to actual needs.

[0162] For example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and modified compounds thereof. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Examples of lithium phosphates with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and modified compounds thereof. All of these materials are commercially available.

[0163] The modifying compound for each of the above materials may be one that performs doping modification and / or surface coating modification on the material.

[0164] The positive electrode layer generally further optionally contains an adhesive, a conductive agent and other optional auxiliary agents.

[0165] By way of example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers.

[0166] By way of example, the adhesive may include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0167] [Negative electrode plate] In a battery, the negative electrode plate generally includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0168] The negative electrode current collector may be a conventional metal foil sheet or a composite current collector (e.g., a metal material may be deposited on a polymer substrate to form a composite current collector). For example, the negative electrode current collector may be a copper foil.

[0169] The specific type of the negative electrode active material is not limited, and any active material known in the art for use in battery negative electrodes may be used. Those skilled in the art can select the material according to their actual needs. For example, the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicone-based materials, and tin-based materials. The silicone-based material may include one or more of silicone element, silicone oxide (e.g., silicon suboxide), silicone carbon composite, silicone nitrogen composite, and silicone alloy. The tin-based material may include one or more of elemental tin, stannic acid compounds, and tin alloys. All of these materials are commercially available.

[0170] In some embodiments, to further improve the energy density of the battery, the negative electrode active material may include a silicone-based material.

[0171] The negative electrode film layer generally further optionally contains an adhesive, a conductive agent and other optional auxiliary agents.

[0172] By way of example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0173] By way of example, the adhesive may include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0174] By way of example, other optional adjuvants may include thickeners and dispersants (eg, sodium carboxymethylcellulose CMC-Na), PTC thermistor materials.

[0175] [Electrolyte] The battery may include an electrolyte, which serves to conduct ions between the positive electrode and the negative electrode, and may include an electrolyte salt and a solvent.

[0176] By way of example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0177] By way of example, the solvent may comprise one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0178] In some embodiments, the electrolyte solution further includes additives, such as an additive for forming a negative electrode film or a positive electrode film, and may further include additives that can improve certain battery performance characteristics, such as an additive for improving the overcharge performance of the battery, an additive for improving the high-temperature performance of the battery, or an additive for improving the low-temperature performance of the battery.

[0179] In some embodiments, the battery may be a lithium ion secondary battery.

[0180] The embodiments of the present application are not particularly limited to the shape of the battery, which may be cylindrical, rectangular, or any other shape. FIG. 8 shows an example of a rectangular structure. secondary Battery 1.

[0181] In some embodiments, the battery may include an outer casing, which is used to package the positive and negative electrodes and the electrolyte.

[0182] In some embodiments, the exterior body may include a case and a cover plate. Here, the case may include a bottom plate and a side plate connected to the bottom plate, the bottom plate and the side plate surrounding the bottom plate forming a storage cavity. The case may have an opening communicating with the storage cavity, and the cover plate may be disposed over the opening to seal the storage cavity.

[0183] The positive electrode plate, the negative electrode plate, and the separator can be wound or stacked to form an electrode assembly. The electrode assembly is packaged in the receiving cavity. The electrolyte can be an electrolytic solution, which is impregnated into the electrode assembly. The number of electrode assemblies included in the battery can be one or more, and can be adjusted according to needs.

[0184] In some embodiments, the battery exterior may be a hard case, such as a hard plastic case, an aluminum case, or a steel case.

[0185] The battery exterior may be a pouch, for example, a bag-like pouch, and the material of the pouch may include plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0186] In some embodiments, the batteries can be assembled into a battery module, and the number of batteries included in the battery module can be multiple, with the specific number being adjustable depending on the application and capacity of the battery module.

[0187] FIG. 9 shows an example of a battery module 2. Referring to FIG. 9, in the battery module 2, a plurality of secondary The batteries 1 may be arranged in a row along the longitudinal direction of the battery module 2. Of course, they may be arranged in any other manner. secondary The battery 1 can be fixed.

[0188] The battery module 2 may further include a housing having an accommodating space, and the plurality of secondary batteries 1 are accommodated in the accommodating space. In some embodiments, the battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0189] 10 and 11 show an example of a battery pack 3. Referring to FIGS. 10 and 11, the battery pack 3 may include a battery box and a plurality of battery modules 2 installed in the battery box. The battery box includes an upper housing 4 and a lower housing 5, and the upper housing 4 is attached to the lower housing 5 as a lid to form a sealed space for accommodating the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0190] [Power consumption equipment] The present application further provides a power consuming device, the power consuming device including the battery for providing electrical energy. Specifically, the battery may be a power source for the power consuming device or an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0191] 12 is an example power consuming device, which may include a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0192] Other examples of power consuming devices may include mobile phones, tablet computers, and laptops, which generally require a low profile and may employ batteries as a power source.

[0193] In order to clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application, the following will be described in more detail with reference to the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is for illustrative purposes only and does not constitute any limitation on the present application and its applications. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without any creative effort are within the scope of protection of the present application.

[0194] 1. Separator manufacturing (1) A PE substrate is provided, the thickness of which is 9 μm, the hole diameter of which is 50 nm, and the porosity of which is 38%.

[0195] (2) Preparation of coating slurry: Composite particles, adhesive (whose glass transition temperature is about 10°C, adhesive polymer (average particle size 1.1 μm) and plasticizer in a mass ratio of 5:1 (wherein 8 wt% of the plasticizer is grafted to the adhesive polymer, based on the weight of the plasticizer), and some deionized water, where the adhesive polymer is 30 wt% isobutyl acrylate + 25 wt% isooctyl acrylate + 5 wt% 2-hydroxypropyl acrylate + 15 wt% styrene + 22 wt% acrylamide + 3 wt% polyethylene glycol copolymer. In The composite particles and the plasticizer were glycerol (the mass ratio of the composite particles to the solid content in the adhesive was 90:10), the organic particles, the dispersant carboxymethylcellulose sodium (CMC-Na), and the wetting agent organosilicon-modified polyether were uniformly mixed in an appropriate amount of deionized water solvent to obtain a coating slurry with a solid content of 12% (calculated by weight).

[0196] (3) The coating slurry prepared in step (2) was applied to two surfaces of the PE substrate using a coater and then dried, where the drying temperature was 50°C and the drying time was 25 seconds, to obtain separator 1.

[0197] Here, the composite particles were prepared by the following steps.

[0198] a. At room temperature, the required monomers are uniformly mixed by stirring in the weight percentages of 19 wt% 2-hydroxyethyl acrylate, 27 wt% n-butyl acrylate, 8 wt% methyl methacrylate, 1 wt% trimethylolpropane triacrylate, 20 wt% acrylonitrile, and 25 wt% acrylamide to obtain a mixed monomer; b. 2 kg of mixed monomer, 60 g of sodium dodecyl sulfate emulsifier, 20 g of ammonium persulfate initiator and 2.40 kg of deionized water were added to a 10 L four-neck flask equipped with a mechanical stirrer, a thermometer and a condenser, and emulsified by stirring at a rotation speed of 1600 rpm for 30 minutes. Then, under nitrogen gas protection, the temperature was raised to 75°C and reacted for 4 hours. After that, the pH was adjusted to 6.5 with a 1 wt% NaOH aqueous solution, and the temperature was immediately lowered to below 40°C and the material was discharged to obtain an emulsion-state organic polymer, the solid content of which was about 45 wt%. c) The dry weight of the organic polymer and silicon dioxide were added to an appropriate amount of deionized water in a mass ratio of 9:1, and the mixture was thoroughly mixed for 1 hour. The solvent was then removed by spray drying to obtain a powder, which was then polished and pulverized to obtain composite particles with a Dv50 of 5 μm.

[0199] The manufacturing process of separators 2-30, 61-62 is the same as that of separator 1, and the different parameters are as shown in Tables 1-3 and 7.

[0200] The manufacturing process of separator 31 is the same as that of separator 1, except that in step (2), the coating slurry is prepared by uniformly mixing composite particles, adhesive, second inorganic particles (the mass ratio of composite particles to second inorganic particles is 20:60), organic particles, dispersant carboxymethylcellulose sodium (CMC-Na), and wetting agent organosilicon-modified polyether in an appropriate amount of solvent deionized water to obtain a coating slurry with a solid content of 30% (calculated by weight).

[0201] The manufacturing process of separators 32-60, 63-64 is the same as that of Example 31, with the different parameters as shown in Tables 4-7.

[0202] The corresponding parameters in the manufacturing process of separator 1-64 are as shown in Table 1-7.

[0203] All materials used in the examples are commercially available. For example, The second inorganic particles may be purchased from Anhui Yishitong Technology Co., Ltd.; The organic particles may be purchased from Ruyuan Dongyangguang Fluoropolymer Co., Ltd. The substrate may be purchased from Shanghai Enjie New Materials Co., Ltd. Dispersants may be purchased from Changshu Weiyi Technology Co., Ltd. Wetting agents may be purchased from The Dow Chemical Company.

[0204] [Table 1] TIFF0007760039000002.tif185168TIFF0007760039000003.tif181168

[0205] [Table 2] TIFF0007760039000005.tif178168TIFF0007760039000006.tif195168

[0206] [Table 3] TIFF0007760039000008.tif189168TIFF0007760039000009.tif182168

[0207] [Table 4] TIFF0007760039000011.tif179168TIFF0007760039000012.tif187168

[0208] [Table 5] TIFF0007760039000014.tif176168TIFF0007760039000015.tif187168TIFF0007760039000016.tif176168

[0209] [Table 6] TIFF0007760039000018.tif179168TIFF0007760039000019.tif194168TIFF0007760039000020.tif176168

[0210] [Table 7] TIFF0007760039000022.tif182168TIFF0007760039000023.tif180168

[0211] 2. Battery manufacturing Example 1 1. Manufacturing of positive electrode plates LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive carbon black (Super P), and adhesive polyvinylidene fluoride (PVDF) were mixed uniformly in a mass ratio of 96.2:2.7:1.1 in an appropriate amount of solvent N-methylpyrrolidone (NMP) to obtain a positive electrode slurry. The positive electrode slurry was then applied to a positive electrode current collector aluminum foil, followed by drying, cold pressing, slitting, and cutting to obtain a positive electrode plate. The positive electrode areal density was 0.207 mg / mm 2 and the compaction degree is 3.5 g / cm 3 is.

[0212] 2. Manufacturing of negative electrode plates The negative electrode active material, artificial graphite, the conductive agent, carbon black (Super P), the adhesive, styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na), were mixed uniformly in a mass ratio of 96.4:0.7:1.8:1.1 in an appropriate amount of deionized water to obtain a negative electrode slurry. The negative electrode slurry was then applied to a negative electrode current collector copper foil, dried, cold pressed, slit, and cut to obtain a negative electrode plate. The negative electrode areal density was 0.126 mg / mm 2 and the compaction degree is 1.7 g / cm 3 is.

[0213] 3. Separator The separator used was the separator 1 manufactured above.

[0214] 4. Electrolyte production Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70 to obtain an organic solvent, and LiPF6, a thoroughly dried electrolyte salt, was dissolved in the mixed solvent to obtain an electrolyte solution with a concentration of 1.0 mol / L.

[0215] 5. Battery manufacturing The positive electrode plate, separator, and negative electrode plate were folded in order, with the separator positioned between the positive and negative electrodes to provide isolation, and then wound to obtain an electrode assembly. The electrode assembly was placed in an outer casing, and the above-prepared electrolyte was injected into the dried secondary battery. The secondary battery was then vacuum packaged, left to stand, chemically formed, and shaped to obtain a secondary battery. The secondary battery of Example 2-64 was manufactured using a method similar to that of Example 1, with the difference being the use of a different separator, and separator 2-64 was used in the secondary battery of Example 2-64.

[0216] 3. Separator compression modulus test method: Sample preparation: 1. Use a blade to punch the separator, and fold it in the order of blade / blank paper / separator / blank paper / press block. Punch 5 layers at a time, 100 layers are one set, and make 3 sets of parallel samples, sample size 60*70mm. 2. Use a chopper to punch the aluminum-plastic film to obtain a size of 90*200mm. 3. Fold the aluminum plastic film in half along the lengthwise direction, fix the center position of the four sides of the punched separator sample with green gum, and leave it in a pocket bag. 4. Use a top packaging machine to package the two long sides of the sample by side packaging, and then vacuum the top to package it. The sealer heating temperature is 185°C. 5. Place the spacer block at the center of the packaged sample, draw a frame and mark it. 6. Use a micrometer to measure the thickness of the separator at the marked positions, four points on the long side and three points on the short side.

[0217] Sample test: 1. Turn on the in-situ expansion test system IEST SWE2110, turn on the operation software MISS, calibrate the pressure, select the compression experiment (transient), calibrate the thickness, 2. Place the sample into the upper and lower jigs, move the upper jig, and ensure that the upper jig is positioned to draw the frame of the sample and mark it. 3. Click on the MISS software to start the experiment. After the test is completed, measure the sample thickness M1 and mark the jig indentation positions on the top and bottom surfaces of the sample with a marker. 4. Repeat steps 2-3 and test again.

[0218] Data Processing: 1. Stress = pressure * 10 / jig area, deformation = initial thickness (M1) - real-time thickness, stress deformation = deformation / initial thickness, 2. Using stress-strain as the abscissa and stress as the ordinate, a stress-strain curve can be created, and a linear fitting of the stress / stress-strain curve from 3 MPa to 5 MPa can be performed to obtain the separator compressive elastic modulus.

[0219] 4. Evaluation of separator resistance performance The test process is as follows:

[0220] (1) Separator preparation: Each separator to be tested is cut into samples of the same size (45.3mm*33.7mm), and the samples are baked in a 60°C environment for at least 4 hours, and then quickly transferred to a 25°C Class 100 clean glove box for preparation. (2) Symmetrical battery area-restricting pocket bag (symmetrical battery area-restricting aluminum plastic bag (aluminum plastic bag is a general-purpose product made of polypropylene and aluminum foil used in pouch cells)) manufacturing: Cu foil to Cu foil (copper foil to copper foil) is used as a blank symmetrical battery for current collector assembly. The area-restricting property of this pocket bag is realized through a green gum middle punch hole. The pocket bag must be baked in an environment of 60°C for at least 4 hours before use, and then quickly transferred to the 25°C class 100 clean glove box described in the previous paragraph (1) for preparation, (3) Assembling symmetrical batteries: Using the positive electrode plate as an electrode, five sets of symmetrical battery samples with different numbers of separator layers (1, 2, 3, 4, 5 layers) were assembled in situ in the glove box described in (1), each set of samples having five parallel samples. Side packaging was performed on the pocket bag using a simple packaging machine, and liquid (300 μL) was injected using a pipette, followed by bottom packaging; (4) Using a jig on the assembled symmetric battery: The assembled symmetric battery was left overnight in the glove box described in (1) above to allow the separator to be fully saturated with the electrolyte. The next day, a metal jig was used to control the pressure of the jig to 0.7 MPa. (5) Electrochemical Impedance Spectroscopy (EIS) Measurement: Before the measurement, the symmetric batteries with different numbers of separator layers were placed in a high-temperature chamber and incubated at 25°C for half an hour, and the EIS was measured at a set temperature (25°C). (For low temperatures (e.g., -25°C-0°C), the incubation time can be correspondingly extended, e.g., about two hours.) (6) The French Bio-Logic VMP3 electrochemical workstation is used, with a voltage of <5V, a current of <400mA, and a current accuracy of 0.1%*100μA. The EIS measurement conditions are: voltage frequency is set to 1MHz-1kHz, the disturbance voltage is set to 5MV, and the fixture pressure is controlled at 0.7MPa. (7) Create a scatter plot of the real part of the EIS data against the negative imaginary part, and plot the data of parallel samples with different and the same number of layers on the same image. The EIS image thus obtained is used as a comparison with the initial EIS data. (8) Remove the points in the non-first quadrant from the EIS image acquired in (7) above to obtain a new EIS image. Perform linear fitting on the scattered points in the first quadrant of the new EIS image to obtain the relevant equation, set y = 0, and obtain the x value, which is the resistance value of the separator with the required electrolyte. By analogy, linear fitting can be performed on the measured EIS data to obtain the resistance value between parallel samples with different numbers of layers.

[0221] 5. Battery performance test 1. Cycle performance of secondary batteries at a clamping force of 0.1 MPa (1) 25℃ cycle performance At 25°C, the secondary batteries prepared in the examples were fixed using three steel jigs, with a 1mm thick insulating mat between the jigs and the batteries. A clamping force of 0.1 MPa was applied, and the batteries were charged at a constant current of 1C to a charge cutoff voltage of 4.2V, then charged at a constant voltage of ≦0.05C and allowed to stand for 5 minutes. Subsequently, the batteries were discharged at a constant current of 0.33C to a discharge cutoff voltage of 2.8V and allowed to stand for 5 minutes, at which point the battery capacity C0 was recorded. According to this method, the batteries were subjected to 1500 charge / discharge cycles, and the battery capacity after 1500 cycles was recorded as C1.

[0222] The cycle capacity retention rate of the battery at 25°C = C1 / C0 x 100%.

[0223] (2) 45℃ cycle performance At 45°C, the secondary battery obtained in the example was fixed using three steel jigs, with a 1mm thick insulating mat between the jig and the battery, and a clamping force of 0.1 MPa was applied. The battery was charged at a constant current of 1C to a charge cutoff voltage of 4.2V, then charged at a constant voltage of ≦0.05C and allowed to stand for 5 minutes, and then discharged at a constant current of 0.33C to a discharge cutoff voltage of 2.8V and allowed to stand for 5 minutes, with the battery capacity at this time recorded as C0. The battery was charged and discharged 1500 times using this method, and the battery capacity at this time recorded as C1.

[0224] The cycle capacity retention rate of the battery at 45°C = C1 / C0 x 100%.

[0225] 2. Cycle performance of secondary batteries at a clamping force of 0.5 MPa (1) 25℃ cycle performance At 25°C, the secondary batteries prepared in the examples were fixed using three steel jigs, with a 1mm thick insulating mat between the jigs and the batteries. A clamping force of 0.5 MPa was applied, and the batteries were charged at a constant current of 1C to a charge cutoff voltage of 4.2V, then charged at a constant voltage of ≦0.05C and allowed to stand for 5 minutes. Subsequently, the batteries were discharged at a constant current of 0.33C to a discharge cutoff voltage of 2.8V and allowed to stand for 5 minutes, at which point the battery capacity C0 was recorded. The batteries were then charged and discharged 1500 times using this method, and the battery capacity after 1500 cycles was recorded as C1.

[0226] The cycle capacity retention rate of the battery at 25°C = C1 / C0 x 100%.

[0227] (2) 45℃ cycle performance At 45°C, the secondary battery obtained in the example was fixed using three steel jigs, with a 1mm thick insulating mat between the jig and the battery, and a clamping force of 0.5 MPa was applied. The battery was charged at a constant current of 1C to a charge cutoff voltage of 4.2V, then charged at a constant voltage of ≦0.05C and allowed to stand for 5 minutes, and then discharged at a constant current of 0.33C to a discharge cutoff voltage of 2.8V and allowed to stand for 5 minutes, with the battery capacity at this time recorded as C0. The battery was charged and discharged 1500 times using this method, and the battery capacity at this time recorded as C1.

[0228] The cycle capacity retention rate of the battery at 45°C = C1 / C0 x 100%.

[0229] Table 8 shows the measured separator and battery performance data for Examples 1-64.

[0230] [Table 8] TIFF0007760039000025.tif250168TIFF0007760039000026.tif92168

[0231] As can be seen from Table 8, the separators of Examples 1-64 all have relatively low resistance and excellent capacity retention. Here, the Dv50 of the first inorganic particles of the composite particles in the separators of Examples 61 and 63 is smaller than the Dv50 of the first inorganic particles of the composite particles in the separators of Examples 1-60, and the Dv50 of the first inorganic particles of the composite particles in the separators of Examples 62 and 64 is larger than the Dv50 of the first inorganic particles of the composite particles in the separators of Examples 1-60. Therefore, the separator resistances of Examples 1-60 are all lower than the separator resistances of Examples 61-64, and the cycle capacity retention rates of the batteries of Examples 1-60 at a clamping force of 0.1 MPa and a clamping force of 0.5 MPa are all better than those of Examples 61-64, thereby demonstrating that the use of the separators of the present application can improve the cycle performance of the battery.

[0232] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present application and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the above embodiments or make equivalent substitutions for some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the relevant technical solutions to depart from the scope of the technical solutions of the embodiments of the present application, and all of them should be included within the scope of the claims and description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in the embodiments can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims. [Explanation of symbols]

[0233] 1: secondary battery, 2: battery module, 3: battery pack, 4: upper housing, 5: lower housing.

Claims

1. A separator, A substrate; a coating formed on at least a portion of the surface of the substrate, the coating including composite particles and an adhesive, the composite particles forming protrusions on the coating surface, the composite particles including polyacrylate particles and first inorganic particles, the first inorganic particles being located between at least two of the polyacrylate particles, the content of the first inorganic particles in the composite particles being bwt%, where b is 1-50.

2. 2. The separator according to claim 1, wherein the compressive modulus of the separator is a MPa, the content of the first inorganic particles in the composite particles is b wt%, and a / b is 1.1-60.

3. 2. The separator according to claim 1, wherein the separator has a compressive modulus of elasticity of a MPa, where a is 60-90.

4. The separator according to claim 1 , wherein the composite particles have a Dv50 of 2.5 μm or more.

5. The separator according to claim 1 , wherein the composite particles include first aggregates, and the first aggregates include at least two of the first inorganic particles.

6. The separator according to claim 5, wherein 0.01 μm≦Dv50 of the first agglomerates≦Dv10 of the composite particles.

7. The separator according to claim 1 , wherein the composite particles include first inorganic particles in the form of primary particles.

8. The separator according to claim 7, wherein the first inorganic particles in the form of primary particles have a Dv50 of 0.01 μm to 1 μm.

9. The separator of claim 1 , wherein the composite particles include second agglomerates, and the second agglomerates include at least two of the polyacrylate particles.

10. The separator according to claim 9, wherein the second aggregates have a Dv50 of 0.3 μm to 5 μm.

11. The separator according to claim 1 , wherein the polyacrylate particles include polyacrylate particles in the form of primary particles and / or polyacrylate particles in the form of secondary particles.

12. The separator according to claim 11, wherein the Dv50 of the polyacrylate particles in primary particle form is 50 nm to 400 nm.

13. The separator according to claim 11, wherein the polyacrylate particles in the secondary particle form have a Dv50 of 2 μm to 15 μm.

14. 2. The separator according to claim 1, wherein the height of each of the projections on both sides is 15 μm to 60 μm.

15. The separator according to claim 5 , wherein the surface of the projection has the first agglomerates.

16. the coating comprises composite particles and an adhesive, the adhesive comprising an adhesive polymer and a plasticizer; The adhesive polymer comprises a copolymer formed from at least one first monomer, at least one second monomer, at least one third monomer, and at least one reactive dispersant, as follows: First monomer: acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, acrylonitrile; Second monomers include acrylic acid C4-C22 alkyl esters, isobutyl acrylate, isooctyl acrylate, tert-butyl acrylate, 2-ethylhexyl (isooctyl) acrylate, cyclohexyl acrylate, ethyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and acrylic methacrylate; Third monomer: 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, methacrylic acid, ethyl acetoacetate, divinylbenzene, epoxy resins having an epoxy value of 0.35-0.50, including divinylbenzene; The separator of claim 1 , comprising a reactive dispersant: polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, polyvinyl alcohol.

17. 17. The separator of claim 16, wherein the plasticizer comprises at least one of a glycerol C4-C10 alkyl diether, a glycerol C4-C10 alkyl monoether, a glycerol C4-C10 carboxylic acid monoester, a glycerol C4-C10 carboxylic acid diester, a propylene glycol C4-C10 alkyl monoether, and glycerol.

18. the coating comprises composite particles, second inorganic particles, and an adhesive, the adhesive comprising a linear copolymer having a hydroxyl group and a carboxylate; The linear copolymers include the polymerization products of various monomers such as: (1) a first type of monomer, the first type of monomer including at least one of acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, methylol acrylamide, acrylamide, styrene, and acrylonitrile; (2) a second type of monomer, the second type of monomer including at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, cyclohexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-hexyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, ethylene urea ethyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, trifluoroethyl methacrylate, ethylene urea ethyl methacrylate, acrylic methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofuryl methacrylate, and trifluoroethyl methacrylate; (3) A third type of monomer, the third type of monomer including at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropyltrimethoxysilane, N-methylolacrylamide, N-butoxymethyl(meth)acrylamide, diacetoneacrylamide, methacrylic acid, ethyl acetoacetate, divinylbenzene, and an epoxy resin having an epoxy value of 0.35 to 0.50; (4) The separator according to claim 1, wherein the fourth type of monomer includes at least one of polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, and polyvinyl alcohol.

19. The separator according to claim 18 , wherein the Dv50 of the composite particles is greater than the Dv50 of the second inorganic particles.

20. The separator according to claim 18, wherein the second inorganic particles have a Dv50 of 0.5 μm to 2 μm.

21. The separator according to claim 18, wherein a mass ratio of the composite particles to the second inorganic particles is (5-30):(50-70).

22. The separator according to claim 1 , wherein the mass ratio of the composite particles to the solid content of the adhesive is (80-90):(5-20).

23. 2. The separator according to claim 1, wherein the coating further comprises organic particles, the organic particles comprising at least one of polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylic acid-based monomer units, copolymer particles of fluorine-containing alkenyl monomer units and acrylate-based monomer units, and particles of modified compounds of each of the above homopolymers or copolymers, and the composite particles and the organic particles form the protrusions on the coating surface.

24. The separator of claim 23 , wherein the organic particles form third aggregates.

25. The separator according to claim 24, wherein the third aggregates have a Dv50 of 5 μm to 30 μm.

26. The separator according to claim 24 , wherein the third aggregate contains organic particles in the form of primary particles, and there is a gap between two adjacent organic particles.

27. The separator according to claim 26, wherein the Dv50 of the organic particles in the form of primary particles is 50 nm to 400 nm.

28. The separator according to claim 22, wherein the mass ratio of the composite particles to the organic particles is (20-90):(0-70).

29. A method for producing the separator according to claim 1, (1) providing a substrate; (2) A method for producing a separator, comprising: forming a coating containing composite particles and an adhesive on at least a portion of the surface of the substrate, wherein the composite particles form protrusions on the coating surface, the composite particles containing polyacrylate particles and first inorganic particles, and the first inorganic particles are disposed between at least two of the polyacrylate particles.

30. 29. A battery comprising the separator of any one of claims 1 to 28.

31. 31. A power consuming device comprising the battery of claim 30, said battery being adapted to provide electrical energy.

Images