Adhesive and manufacturing method thereof, separator, electrode assembly, battery cell, battery and power consumption device

Abstract

The present application relates to the field of battery technology, in particular to an adhesive and its manufacturing method, and a separator, electrode assembly, battery cell, battery and power consumption device containing the adhesive. The adhesive includes a core layer structure and a shell layer structure provided on the surface of the core layer structure, the core layer structure includes a polyacrylate-based polymer, and the shell layer structure includes a polyvinylidene fluoride polymer, and the polyvinylidene fluoride is a homopolymer, the crystallinity is about 50%, and the adhesive strength is insufficient. Therefore, the present application improves the crystallinity of the polyvinylidene fluoride polymer in the adhesive with the core-shell structure by coating the polyacrylate-based polymer with the polyvinylidene fluoride polymer to obtain an adhesive with a core-shell structure, thereby realizing the improvement of the adhesive performance of the adhesive with the core-shell structure, and the adhesive improves the adhesive strength between the separator and the electrode plate.

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and in particular to adhesives and methods for manufacturing the same, as well as separators, electrode assemblies, battery cells, batteries and power consuming devices. [CROSS-REFERENCE TO RELATED APPLICATIONS]

[0002] This application claims priority from a Chinese patent application filed on January 4, 2023, bearing application number 202310009894.X, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] With the rapid increase in portable electronic devices, electric vehicles, etc., the demand for power batteries is constantly increasing, and the electrochemical performance of batteries is also attracting more and more attention.

[0004] Currently, the battery core of the battery has the problem of opening, that is, gaps easily form between the electrode plates and the separator, which leads to poor battery cycling performance. Summary of the Invention

[0005] The main object of the present application is to provide an adhesive, which is intended to improve the adhesive strength between the separator and the electrode plate, thereby improving the cycle performance of the battery.

[0006] To achieve the above object, the present application provides an adhesive, the adhesive including a core layer structure and a shell layer structure provided on a surface of the core layer structure, the core layer structure including a polyacrylate-based polymer, and the shell layer structure including a polyvinylidene fluoride polymer.

[0007] According to the adhesive of the present application, the adhesive comprises a core layer structure and a shell layer structure formed on the surface of the core layer structure, the core layer structure comprises a polyacrylate polymer, and the shell layer structure comprises a polyvinylidene fluoride polymer. Polyvinylidene fluoride is a homopolymer with a crystallinity of about 50% and insufficient adhesive strength. Therefore, the present application coats a polyacrylate polymer with a polyvinylidene fluoride polymer to obtain a core-shell structure adhesive, thereby improving the crystallinity of the polyvinylidene fluoride polymer in the core-shell structure adhesive and improving the adhesive performance of the core-shell structure adhesive, which improves the adhesive strength between the separator and the electrode plate.

[0008] Optionally, the shell layer structure includes a plurality of cases, and the plurality of cases are disposed at intervals on the surface of the core layer structure.

[0009] In order to further reduce the crystallinity of the polyvinylidene fluoride polymer in the shell layer structure, the degree of crosslinking of the polyvinylidene fluoride polymer is reduced, thereby reducing the crystallinity, i.e., the polyvinylidene fluoride polymer casings are not continuously coated on the surface of the core layer structure, but are attached to the surface of the core layer structure at intervals, resembling a raspberry-like structure. As can be seen, the shell layer structure is equivalent to being composed of a plurality of casings, with gaps existing between adjacent casings, allowing the surface of the core layer structure to be exposed at the gaps. In this way, not only is the crystallinity of the polyvinylidene fluoride polymer reduced, but the core layer structure is also exposed, and since the core layer structure has relatively good adhesive properties, the core layer structure exposed between the casings can also enhance adhesive performance. Furthermore, the raspberry-like core-shell structure has a larger specific surface area than a core layer structure fully coated with a shell layer, and thus the surface structure with adhesive function can perform a greater adhesive function.

[0010] Optionally, the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (2-100):1, and optionally (10-90):1.

[0011] To obtain the above-mentioned low-crosslinked shell layer structure, the mass of the core layer structure is made greater than the mass of the shell layer structure, so that the surface of the core layer structure is not completely covered with the shell layer structure, thereby leaving some of the structure exposed on the surface of the core layer structure, thereby obtaining the raspberry-like core-shell structure. Here, the mass of the core layer structure is greater than the mass of the shell layer structure, and the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer may be (2 to 100):1, where the above (2 to 100):1 range includes the minimum and maximum values ​​within this range and values ​​between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 2:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc.

[0012] Optionally, the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (10-90):1.

[0013] In the above (10-90):1, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples and 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

[0014] Optionally, the adhesive has a volume average particle size Dv50 of 0.5 μm-50 μm, optionally 7 μm-8 μm.

[0015] Theoretically, the volume average particle diameter Dv50 of the adhesive in the present application may be less than 0.5 μm or more than 50 μm. However, considering that the adhesive in the present application is used in a separator, the volume average particle diameter Dv50 of the adhesive cannot be too large or too small. If the adhesive is too small, it will easily clog the pores of the separator, reducing the permeability of lithium ions through the separator. If the adhesive is too large, a thick coating will be formed when the adhesive is applied to the separator. Since this affects the energy density of the battery produced later, the volume average particle diameter Dv50 of the adhesive is 0.5 μm-50 μm, and in the above 0.5 μm-50 μm, the value includes the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, and 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0016] Optionally, the adhesive has a volume average particle size Dv50 of 7 μm-8 μm.

[0017] When the volume average particle diameter Dv50 of the adhesive is 7 μm-8 μm, the performance of the resulting separator is excellent. In the above 7 μm-8 μm range, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 7 μm, 7.5 μm, 8 μm, etc.

[0018] Optionally, the constituent monomers of the polyacrylate polymer include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer.

[0019] The constituent monomers of the polyacrylate polymer in the present application include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer, and by subjecting the three types of monomers to a crosslinking reaction to obtain a polymer, it is possible to control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0020] Alternatively, the molar ratio of the first flexible polymerizable monomer to the second polar polymerizable monomer to the third molecular weight adjusting monomer is 1:(0.01-0.8):(0.01-0.15), and optionally 1:(0.05-0.7):(0.05-0.12).

[0021] When the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.01-0.8):(0.01-0.15), the adhesive has excellent adhesive properties. In the above 1:(0.01-0.8):(0.01-0.15) range, the values ​​include the minimum and maximum values ​​within this range, as well as values ​​between these minimum and maximum values. Specific examples include the point values ​​in the examples and 1:0. Examples include, but are not limited to, 1:0.01, 1:0.1:0.01, 1:0.4:0.01, 1:0.8:0.01, 1:0.01:0.05, 1:0.01:0.1, 1:0.01:0.15, 1:0.1:0.01, 1:0.1:0.05, 1:0.1:0.15, 1:0.4:0.01, 1:0.4:0.05, 1:0.4:0.15, 1:0.8:0.01, 1:0.8:0.05, 1:0.8:0.15, etc.

[0022] Optionally, the molar ratio of the first flexible polymerizable monomer to the second polar polymerizable monomer to the third molecular weight adjusting polymerizable monomer is 1:(0.05-0.7):(0.05-0.12).

[0023] When the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.05-0.7):(0.05-0.12), the adhesive has excellent adhesive properties. In the above 1:(0.05-0.7):(0.05-0.12), the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 1:0.05:0.05, 1:0.1:0.05, 1:0.4:0.05, 1:0.7:0.05, 1:0.1:0.05, 1:0.1:0.1, 1:0.1:0.12, etc.

[0024] Optionally, the structure of the first polymerizable flexible monomer contains an ester bond, the structure of the second polymerizable polar monomer contains a cyano group, and the structure of the third polymerizable molecular weight adjusting monomer contains an amide bond.

[0025] The ester bond can improve the flexibility of the molecular chain, the cyano group can improve the polarity of the monomer, and the amide bond has polarity and is likely to form hydrogen bonds, thereby improving adhesiveness. By containing an ester bond in the structure of the first polymerizable flexible monomer, containing a cyano group in the structure of the second polymerizable polar monomer, and containing an amide bond in the structure of the third polymerizable molecular weight adjusting monomer, the polymer obtained by polymerizing the above three types of monomers can control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0026] Optionally, the first polymerizable flexible monomer is an acrylate-based monomer, the second polymerizable polar monomer is an acrylonitrile-based monomer, and the third polymerizable molecular weight-controlling monomer is an acrylamide-based monomer.

[0027] The acrylate monomer can improve the swelling resistance of the polymer, and also adjust the glass transition temperature of the polymer as a flexible monomer segment in the molecular segment, thereby improving the toughness of the adhesive when applied, thereby contributing to the exertion of good adhesive action.

[0028] The acrylonitrile monomer has a cyano group with strong polarity, which contributes to improving ionic conductivity and adhesiveness.

[0029] The acrylamide monomer not only serves to adjust the molecular weight, but also has relatively good adhesive properties.

[0030] The polymers produced by the above three kinds of monomers can control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0031] Alternatively, the acrylate monomer may include at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl 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, and 2-hydroxypropyl methacrylate; and / or the acrylonitrile-based monomer includes at least one of acrylonitrile and methacrylonitrile, And / or, the acrylamide-based monomer includes at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide.

[0032] The acrylate monomer contributes to improving the adhesive properties of the adhesive, and the acrylate monomer may include at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl 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, and 2-hydroxypropyl methacrylate. In other words, the constituent monomers of the polyacrylate polymer may include one of the above acrylate monomers or multiple of the above acrylate monomers, and are not specifically limited.

[0033] The acrylonitrile-based monomer contributes to improving the adhesive properties of the adhesive, and the acrylonitrile-based monomer includes at least one of acrylonitrile and methacrylonitrile. In other words, the constituent monomers of the polyacrylate-based polymer may include one of the above acrylonitrile-based monomers or may include multiple of the above acrylonitrile-based monomers, and are not specifically limited.

[0034] The acrylamide-based monomer contributes to improving the adhesive properties of the adhesive, and the acrylamide-based monomer includes at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide. In other words, the constituent monomers of the polyacrylate-based polymer may include one of the above acrylamide-based monomers or multiple acrylamide-based monomers, and are not specifically limited.

[0035] Optionally, the polyvinylidene fluoride polymer comprises at least one of vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-perfluorobutene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, or vinylidene fluoride-vinyl fluoride copolymer.

[0036] In addition to having good chemical resistance and corrosion resistance, polyvinylidene fluoride polymers also have special properties such as high temperature resistance, oxidation resistance, weather resistance, and radiation resistance, as well as piezoelectric, dielectric, and thermoelectric properties, and are often used in lithium-ion battery separators.

[0037] The polyvinylidene fluoride polymer used in the present application includes at least one of vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-perfluorobutene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and vinylidene fluoride-vinyl fluoride copolymer. In other words, the polyvinylidene fluoride polymer may include one of the above polyvinylidene fluoride polymers or multiple of the above polyvinylidene fluoride polymers, and is not specifically limited.

[0038] The present application provides a method for producing an adhesive, a step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating them to react with each other to obtain a core layer seed emulsion; and adding water, an emulsifier, an initiator, and constituent monomers of polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating under reaction pressure to cause a polymerization reaction, thereby obtaining an adhesive with a core-shell structure.

[0039] In this application, a polyacrylate polymer for the core layer is first obtained by emulsion polymerization, and then a polyvinylidene fluoride polymer is prepared by emulsion polymerization to obtain a shell layer on the surface of the core layer structure, thereby finally forming an adhesive having a core-shell structure.

[0040] Alternatively, the ratio of the constituent monomer mass of the polyacrylate polymer to the constituent monomer mass of the polyvinylidene fluoride polymer is (2 to 100):1, and optionally (10 to 90):1.

[0041] In order to obtain a core-shell structure with a raspberry-like structure, the constituent monomer mass of the polyacrylate polymer of the core layer is made larger than the constituent monomer mass of the polyvinylidene fluoride polymer of the shell layer, so that the structural surface area of ​​the formed core layer is sufficiently large, i.e., the mass of the core layer is large and the structure is large, while the mass of the shell layer is small, making it difficult for the shell layer structure to completely cover the surface of the core layer; i.e., the polyvinylidene fluoride polymer is attached to the surface of the core layer without being connected, resulting in a low degree of crosslinking and a low degree of crystallinity of the polyvinylidene fluoride polymer, and thereby this core-shell structure reduces the crystallinity of the polyvinylidene fluoride polymer and improves the adhesive performance of the adhesive produced. Therefore, as shown in FIG. 2, the ratio of the constituent monomer mass of the polyacrylate polymer to the constituent monomer mass of the polyvinylidene fluoride polymer is (2 to 100):1, and in the above (2 to 100):1, the value includes the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 2:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc.

[0042] Optionally, the ratio of the constituent monomer mass of the polyacrylate polymer to the constituent monomer mass of the polyvinylidene fluoride polymer is (10 to 90):1.

[0043] In the above (10-90):1, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples and 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

[0044] Optionally, in the step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating them to react with each other to obtain a core layer seed emulsion, a step of mixing and stirring water, an emulsifier, and constituent monomers of a polyacrylate polymer to obtain a core layer monomer pre-emulsion; After the temperature is raised, the initiator is added in batches, and the mixture is stirred to react, and after the reaction is completed, a core layer seed emulsion is obtained.

[0045] To avoid explosive polymerization under heated conditions due to excessive addition of the initiator at once caused by adding the initiator before heating, this application first mixes and stirs water, emulsifier, and constituent monomers of the polyacrylate polymer to obtain a core layer monomer pre-emulsion. To avoid excessive addition of one lot of initiator that would result in explosive polymerization if one lot of initiator were added dropwise, the initiator is added in lots after heating, and the mixture is stirred to react, and the core layer seed emulsion is obtained after the reaction is completed.

[0046] Optionally, the constituent monomers of the polyvinylidene fluoride polymer include vinylidene fluoride; Alternatively, the constituent monomers of the polyvinylidene fluoride polymer include at least one of vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, tetrafluoropropylene, trifluoropropylene, perfluorobutene, tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, and vinyl fluoride.

[0047] Polyvinylidene fluoride polymer is a polymer containing vinylidene fluoride as a monomer, and the monomer of polyvinylidene fluoride polymer further contains, in addition to vinylidene fluoride, at least one of hexafluoropropylene, pentafluoropropylene, tetrafluoropropylene, trifluoropropylene, perfluorobutene, tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, and vinyl fluoride. That is, polyvinylidene fluoride polymer may be a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride and another fluorine-containing ethylene, and is not specifically limited.

[0048] The present application provides a separator, which includes the above adhesive or an adhesive produced by the above adhesive production method on the separator.

[0049] The separator is coated with the adhesive, which can improve the adhesive performance between the electrode plate and the adhesive and solve the problem of openings in the conventional pre-cooling pressing process of the battery core.

[0050] An embodiment of the present application provides an electrode assembly, the electrode assembly including the separator described above.

[0051] The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator, and the adhesive is coated on the separator, thereby bonding the electrode plate and the separator together and improving the problem of openings between the electrode plate and the separator.

[0052] An embodiment of the present application provides a battery cell, which includes an electrode assembly as described above.

[0053] By applying the electrode assembly to a battery cell, the cycle performance of the large jig of the battery cell can be improved.

[0054] An embodiment of the present application provides a battery, which includes the battery cell described above.

[0055] An embodiment of the present application provides a power consumption device, which includes the above battery cell or the above battery. [Brief explanation of the drawings]

[0056] In order to more clearly explain the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings that need to be used in the embodiments or the prior art description. It is obvious that the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the structures shown in these drawings without any creative effort. The realization of the objectives, functional features and advantages of the present application will be further described with reference to the drawings in conjunction with the embodiments. [Figure 1] 1 is a flow chart of a method for manufacturing an adhesive according to an embodiment of the present application. [Figure 2] 1 is a flow chart of a method for manufacturing an adhesive according to an embodiment of the present application. [Figure 3] 1 is a scanning electron microscope view of an adhesive according to an example of the present application. [Figure 4] FIG. 4 is an enlarged scanning electron microscope view of the adhesive in FIG. 3. [Figure 5] 1 is a schematic diagram of an electrode assembly according to an embodiment of the present application. [Figure 6] FIG. 6 is an exploded view of the electrode assembly according to the embodiment of the present application shown in FIG. 5. [Figure 7] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 8]1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 9] FIG. 9 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 8. [Figure 10] 1 is a schematic diagram of a power consuming device in which an electrode assembly according to an embodiment of the present application is used as a power source; DETAILED DESCRIPTION OF THE INVENTION

[0057] The following clearly and completely describes the technical solutions in the embodiments of the present application, in conjunction with the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, not all of the embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts fall within the scope of protection of the present application.

[0058] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the adhesive of the present application, its manufacturing method, and a separator, electrode assembly, battery cell, battery, and power consumption device each including the adhesive will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0059] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values ​​and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0061] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0062] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0063] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "include" may further include or include other components not listed, or may include or include only the listed components.

[0064] Unless otherwise stated, in this application, the term "or" is inclusive. For example, 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).

[0065] The battery core of the battery has the problem of opening, that is, gaps easily form between the plates and the separator, which leads to poor battery cycling performance.

[0066] For example, polyvinylidene fluoride, the most commonly used adhesive, is widely used in separators, but at present, the price of polyvinylidene fluoride is rising rapidly, causing a tight market supply. Coating the surface of lithium battery separators with polyvinylidene fluoride polymer can partially solve the separator's high-temperature shrinkage problem by winding the battery core and then cold pressing it. However, general polyvinylidene fluoride is a homopolymer with a crystallinity of about 50%, which means it has insufficient adhesion to the positive and negative electrodes, often causing the battery core to open up, and therefore cannot meet the performance requirements of coated separators for power lithium-ion batteries.

[0067] That is, coating the surface of a lithium battery separator with polyvinylidene fluoride polymer can partially solve the separator's high-temperature shrinkage problem, and cold pressing is performed after winding the battery core. However, typical polyvinylidene fluoride is a homopolymer with a crystallinity of about 50%, which means that the adhesive strength with the positive and negative electrodes is insufficient, often resulting in openings in the battery core. Openings in the battery core form gaps between the electrodes and the separator, loosening the overall battery core structure, reducing the hardness of the battery core, and deteriorating the cycle performance of the battery core.

[0068] The battery core is formed by bonding positive and negative electrode plates and a separator. The battery core has a certain hardness, i.e., the bonded positive and negative electrode plates and separator are tightly supported by each other to form a structure with a certain thickness. This structure with a certain thickness also has a certain hardness, and the negative electrode expands during charging and discharging. If the adhesive strength is weak, gaps will form between the positive and negative electrode plates and the separator, preventing the positive and negative electrode plates and the separator from being tightly supported by each other. This causes the battery core to loosen and its hardness to decrease, resulting in poor power performance of the battery core, such as reduced rate performance and poor cycle performance. For example, in electric vehicles, loosening of the battery core can slow the battery's charging speed and reduce the battery's cycle performance, directly shortening the battery life and requiring frequent battery replacement, which increases the cost of electric vehicles for consumers.

[0069] Based on this, the present application provides an adhesive, the adhesive comprising a core layer structure and a shell layer structure provided on a surface of the core layer structure, the core layer structure comprising a polyacrylate-based polymer, and the shell layer structure comprising a polyvinylidene fluoride polymer.

[0070] An adhesive is a material that has adhesive properties for bonding different substances together.

[0071] The core-shell structure is composed of a central core and a shell covering the outer layer.

[0072] The core layer structure is a structure that is located inside the core-shell structure and is covered with an outer shell.

[0073] The shell layer structure is a structure that is located outside the core-shell structure and covers the surface of the core layer structure.

[0074] A polyacrylate polymer is a polymer made of acrylate monomers.

[0075] Polyvinylidene fluoride polymers are polymers in which vinylidene fluoride is the monomer.

[0076] The present application discloses a core-shell adhesive by coating a polyacrylate polymer with a polyvinylidene fluoride polymer, thereby improving the crystallinity of the polyvinylidene fluoride polymer in the core-shell adhesive and improving the adhesive performance of the core-shell adhesive, thereby enhancing the adhesive strength between the separator and the electrode plate. The adhesive of the present application exhibits excellent adhesive performance, preventing separation between the electrode plate and the separator during electrode plate expansion, maintaining good hardness of the battery core, and improving the dynamic and cycling performance of the battery core.

[0077] Theoretically, with an increase in crystallinity, the molecular chain arrangement becomes tighter and more orderly, the void ratio becomes lower, the intermolecular interaction force increases, and segment movement becomes more difficult. As a result, the yield stress, strength, modulus, and hardness of the polymer all improve, but the elongation at break and impact toughness decrease. Obviously, the crystallization makes the polymer hard and brittle, and the adhesive performance also decreases.

[0078] The present application uses a polyvinylidene fluoride polymer to coat a polyacrylate polymer. Compared to pure polyvinylidene fluoride, the core-shell structure of the present application has a lower overall crystallinity and improved adhesive performance. The use of this core-shell structure adhesive can improve the adhesion between the separator and the electrode plate, preventing the problem of opening in the battery core. At the same time, the reduced crystallinity increases the disordered molecular structure of the adhesive, increasing the porosity and improving the adhesive's liquid wettability. Coating the adhesive on the separator improves the separator's wettability with the electrolyte, which is beneficial for improving the battery's cycle performance.

[0079] In some embodiments, the shell layer structure includes a plurality of cases, the plurality of cases being spaced apart on the surface of the core layer structure.

[0080] As shown in Figures 3 and 4, to further reduce the crystallinity of the polyvinylidene fluoride polymer in the shell layer structure, the degree of crosslinking of the polyvinylidene fluoride polymer is reduced, thereby reducing the crystallinity, i.e., the polyvinylidene fluoride polymer casings are not continuously coated on the surface of the core layer structure, but are attached to the surface of the core layer structure at intervals, resembling a raspberry-like structure. As can be seen, the shell layer structure is equivalent to being composed of multiple casings, with gaps existing between adjacent casings, allowing the surface of the core layer structure to be exposed at the gaps. This not only reduces the crystallinity of the polyvinylidene fluoride polymer, but also exposes the core layer structure, which has relatively good adhesive properties, thereby reinforcing the adhesive performance of the core layer structure exposed between the casings. Furthermore, the raspberry-like core-shell structure has a larger specific surface area than a core layer structure fully coated with a shell layer, allowing the surface structure with adhesive function to perform more effectively.

[0081] As can be seen, the functional groups on the surfaces of the polyvinylidene fluoride polymer shell layer and the polyacrylate-based polymer core layer do not undergo a crosslinking reaction, and the bond between the core layer and the shell layer is mainly an ionic bonding mechanism, and the constituent monomers of the polyvinylidene fluoride polymer are adsorbed onto the constituent monomers of the polyacrylate-based polymer through the action of ionic bonds, van der Waals forces, etc.

[0082] In some embodiments, the weight ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (2-100):1, and optionally (10-90):1.

[0083] In the mass ratio test method, when the mass of the monomer added during the reaction process in the adhesive manufacturing process to produce the core layer structure is recorded as m and the mass of the monomer added during the reaction process to produce the shell layer structure is recorded as n, the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is m:n.

[0084] To obtain the above-mentioned low-crosslinked shell layer structure, the mass of the core layer structure is made greater than the mass of the shell layer structure, so that the surface of the core layer structure is not completely covered with the shell layer structure, thereby leaving some of the structure exposed on the surface of the core layer structure, thereby obtaining the raspberry-like core-shell structure. Here, the mass of the core layer structure is greater than the mass of the shell layer structure, and the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer can be (2 to 100):1, where the above (2 to 100):1 includes the minimum and maximum values ​​within this range and values ​​between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 2:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc.

[0085] In some embodiments, the weight ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (10-90):1.

[0086] In the above (10-90):1, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples and 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

[0087] In some embodiments, the adhesive has a volume average particle size Dv50 of 0.5 μm-50 μm, optionally 7 μm-8 μm.

[0088] The volume average particle size Dv50 of the adhesive can be tested using methods known in the art, for example, see GB / T 19077-2016, characterization tests can be performed using a Malvern Mastersizer, for example, testing can be performed using an instrument such as Malvern's Mastersizer-3000.

[0089] Theoretically, the volume average particle diameter Dv50 of the adhesive in the present application may be less than 0.5 μm or more than 50 μm. However, considering that the adhesive in the present application is used in a separator, the volume average particle diameter Dv50 of the adhesive cannot be too large or too small. If the adhesive is too small, it will easily clog the pores of the separator, reducing the permeability of lithium ions through the separator. If the adhesive is too large, a thick coating will be formed when the adhesive is applied to the separator. Since this affects the energy density of the battery produced later, the volume average particle diameter Dv50 of the adhesive is 0.5 μm-50 μm, and in the above 0.5 μm-50 μm, the value includes the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, and 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0090] In some embodiments, the adhesive has a volume average particle size Dv50 of 7 μm-8 μm.

[0091] When the volume average particle diameter Dv50 of the adhesive is 7 μm-8 μm, the performance of the resulting separator is excellent. In the above 7 μm-8 μm range, the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 7 μm, 7.5 μm, 8 μm, etc.

[0092] In some embodiments, the constituent monomers of the polyacrylate polymer include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight modifying monomer.

[0093] Regarding flexible monomers, the glass transition temperature of the homopolymer of the flexible monomer is lower than that of the homopolymer of the rigid monomer. The flexible monomer has a certain flexibility relative to the rigid group, allowing the segments to move freely. The flexible monomer segments adjust the glass transition temperature of the polymer and improve the toughness of the adhesive when applied, contributing to the exertion of good adhesive properties.

[0094] A polar monomer is a monomer containing a polar group, and the polar monomer contributes to improving the adhesiveness of the polymer.

[0095] The molecular weight adjusting monomer is a monomer that is involved in a crosslinking reaction and is used to adjust the molecular weight of the polymer. Ensuring that the molecular weight of the adhesive falls within a certain range contributes to improving adhesiveness.

[0096] The constituent monomers of the polyacrylate polymer in the present application include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer, and by subjecting the three types of monomers to a crosslinking reaction to obtain a polymer, it is possible to control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0097] The softening point of the modified polymer is lower than that of pure polyvinylidene fluoride-based polymers, and when the battery core is pre-cold pressed, the adhesive can fully penetrate into the gaps between the positive and negative electrode plates and the separator. That is, when there is a gap between the electrode plate and the separator, the adhesive penetrates into the gap, effectively connecting the electrode plate and the separator, and the adhesive is less likely to come out of the gap. During expansion of the electrode plate, the adhesive retains its toughness and can effectively connect the two even during expansion, allowing the adhesive to fully exert its adhesive performance, further contributing to improving the dynamic performance of the battery and the cycle performance of the large jig.

[0098] The softening point is the temperature at which a substance softens. It is related not only to the structure of a polymer but also to the molecular weight of the polymer. In the present application, the softening point of the polymer is improved by adjusting the molecular weight of the polymer with a third polymerization molecular weight adjusting monomer.

[0099] Here, the cycle performance of the large jig refers to one of the cycle functional test performances of the battery core. During the test, a jig is attached to the battery core, and a certain force is applied to the jig to press the battery core. When the battery core is fully charged, expansion occurs, and the battery core is deformed due to the dual compression of the clamping force of the jig and the expansion force. This test is used to test the shape retention and pressure resistance of the battery core. When the adhesive of this solution is used, the adhesive performance is good, so the expansion of the battery core is reduced and the shape retention of the battery core is relatively good. The battery core using the adhesive of this application has relatively good performance retention under the test conditions of the large jig, and the battery core obtained using the adhesive of this solution has excellent deformation retention. When the battery core is assembled to form a battery, the battery core is less likely to deform, so the space required for installing the battery core in the battery can be saved, thereby making the battery volume smaller. Therefore, if the battery core is easily deformed, it will press on the structure near the battery core. To avoid this phenomenon, a larger space is required to accommodate the deformed battery core, that is, space in the battery needs to be reserved to accommodate the deformed part of the battery core, thereby occupying more space within the battery.

[0100] At the same time, the good cycle performance of the large jig for the battery core also means that the cycle performance of the battery core is good. For example, if the battery core expands, the gap between the electrode plates and the separator becomes larger, which lengthens the path for lithium ions to pass through the positive and negative electrodes, resulting in poor cycle performance.

[0101] In some embodiments, the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.01-0.8):(0.01-0.15), optionally 1:(0.05-0.7):(0.05-0.12).

[0102] The molar ratio test method involves recording the number of moles of each type of monomer added during the reaction process to produce the shell layer structure during the adhesive production process, where the number of moles of each type of monomer is calculated by dividing the mass of each type of monomer by the molecular weight of each type of monomer. If the number of moles of the first polymerizable flexible monomer is defined as a, the number of moles of the second polymerizable polar monomer is defined as b, and the number of moles of the third polymerizable molecular weight adjusting monomer is defined as c, the molar ratio of the first polymerizable flexible monomer, the second polymerizable polar monomer, and the third polymerizable molecular weight adjusting monomer is a:b:c.

[0103] When the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.01-0.8):(0.01-0.15), the adhesive has excellent adhesive properties. In the above 1:(0.01-0.8):(0.01-0.15) range, the values ​​include the minimum and maximum values ​​within this range, as well as values ​​between these minimum and maximum values. Specific examples include the point values ​​in the examples and 1:0. Examples include, but are not limited to, 1:0.01, 1:0.1:0.01, 1:0.4:0.01, 1:0.8:0.01, 1:0.01:0.05, 1:0.01:0.1, 1:0.01:0.15, 1:0.1:0.01, 1:0.1:0.05, 1:0.1:0.15, 1:0.4:0.01, 1:0.4:0.05, 1:0.4:0.15, 1:0.8:0.01, 1:0.8:0.05, 1:0.8:0.15, etc.

[0104] In some embodiments, the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.05-0.7):(0.05-0.12).

[0105] When the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.05-0.7):(0.05-0.12), the adhesive has excellent adhesive properties. In the above 1:(0.05-0.7):(0.05-0.12), the values ​​include the minimum and maximum values ​​of this range, and each value between such minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the examples, as well as 1:0.05:0.05, 1:0.1:0.05, 1:0.4:0.05, 1:0.7:0.05, 1:0.1:0.05, 1:0.1:0.1, 1:0.1:0.12, etc.

[0106] In some embodiments, the structure of the first polymerizable flexible monomer contains an ester bond (-COOR (where R is typically another non-H group such as an alkyl group)), the structure of the second polymerizable polar monomer contains a cyano group (-C₃N), and the structure of the third polymerizable molecular weight-controlling monomer contains an amide bond (-CO-NH-).

[0107] The ester bond can improve the flexibility of the molecular chain, the cyano group can improve the polarity of the monomer, and the amide bond has polarity and is likely to form hydrogen bonds, thereby improving adhesiveness. By containing an ester bond in the structure of the first polymerizable flexible monomer, containing a cyano group in the structure of the second polymerizable polar monomer, and containing an amide bond in the structure of the third polymerizable molecular weight adjusting monomer, the polymer obtained by polymerizing the above three types of monomers can control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0108] In some embodiments, the first polymerizable flexible monomer is an acrylate-based monomer, the second polymerizable polar monomer is an acrylonitrile-based monomer, and the third polymerizable molecular weight controlling monomer is an acrylamide-based monomer.

[0109] The acrylate monomer can improve the swelling resistance of the polymer, and also adjust the glass transition temperature of the polymer as a flexible monomer segment in the molecular segment, thereby improving the toughness of the adhesive when applied, thereby contributing to the exertion of good adhesive action.

[0110] The acrylonitrile monomer has a cyano group with strong polarity, which contributes to improving ionic conductivity and adhesiveness.

[0111] The acrylamide monomer not only serves to adjust the molecular weight, but also has relatively good adhesive properties.

[0112] The polymers produced by the above three kinds of monomers can control the molecular weight and glass transition temperature of the polymer, thereby improving the adhesive performance of the adhesive.

[0113] In some embodiments, the acrylate monomers include at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl 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, and 2-hydroxypropyl methacrylate; and / or the acrylonitrile monomers include at least one of acrylonitrile and methacrylonitrile; and / or the acrylamide monomers include at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide.

[0114] The acrylate monomer contributes to improving the adhesive properties of the adhesive, and the acrylate monomer may include at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl 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, and 2-hydroxypropyl methacrylate. In other words, the constituent monomers of the polyacrylate polymer may include one of the above acrylate monomers or multiple of the above acrylate monomers, and are not specifically limited.

[0115] The acrylonitrile-based monomer contributes to improving the adhesive properties of the adhesive, and the acrylonitrile-based monomer includes at least one of acrylonitrile and methacrylonitrile. In other words, the constituent monomers of the polyacrylate-based polymer may include one of the above acrylonitrile-based monomers or may include multiple of the above acrylonitrile-based monomers, and are not specifically limited.

[0116] The acrylamide-based monomer contributes to improving the adhesive properties of the adhesive, and the acrylamide-based monomer includes at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide. In other words, the constituent monomers of the polyacrylate-based polymer may include one of the above acrylamide-based monomers or multiple acrylamide-based monomers, and are not specifically limited.

[0117] In some embodiments, the polyvinylidene fluoride polymer comprises at least one of vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-perfluorobutene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, or vinylidene fluoride-vinyl fluoride copolymer.

[0118] In addition to having good chemical resistance and corrosion resistance, polyvinylidene fluoride polymers also have special properties such as high temperature resistance, oxidation resistance, weather resistance, and radiation resistance, as well as piezoelectric, dielectric, and thermoelectric properties, and are often used in lithium-ion battery separators.

[0119] The polyvinylidene fluoride polymer used in the present application includes at least one of vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-perfluorobutene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and vinylidene fluoride-vinyl fluoride copolymer. In other words, the polyvinylidene fluoride polymer may include one of the above polyvinylidene fluoride polymers or multiple of the above polyvinylidene fluoride polymers, and is not specifically limited.

[0120] As shown in FIG. 1 , the present application further provides a method for manufacturing an adhesive, a step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating them to react with each other to obtain a core layer seed emulsion; and adding water, an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating under reaction pressure to cause a polymerization reaction to obtain an adhesive.

[0121] In this application, a polyacrylate polymer for the core layer is first obtained by emulsion polymerization, and then a polyvinylidene fluoride polymer is prepared by emulsion polymerization to obtain a shell layer on the surface of the core layer structure, thereby finally forming an adhesive having a core-shell structure.

[0122] Regarding emulsion polymerization, emulsion polymerization is a process in which a monomer is dispersed in water with an emulsifier by mechanical stirring to form an emulsion, and then an initiator is added to start the polymerization of the monomer.

[0123] The core-shell structure is composed of a central core and a shell covering the outer layer.

[0124] The seed emulsion is prepared by first preparing a seed latex from a small amount of monomers by a general emulsion polymerization method, and then adding a small amount of the seed latex to a proper emulsion polymerization recipe, and carrying out a polymerization reaction with the latex particles of the seed emulsion as the core, so that the latex particles grow continuously.

[0125] A pre-emulsion is a solution obtained by pre-emulsifying a monomer. Emulsification involves uniformly dispersing a liquid into another incompatible liquid in the form of extremely small droplets, mixing and stirring water, an emulsifier, and the constituent monomers of the polyacrylate polymer, and dispersing the constituent monomers of the polyacrylate polymer in water by the action of the emulsifier.

[0126] Regarding emulsifiers, emulsifiers are substances that can convert incompatible oil and water into emulsions that are less likely to stratify. Emulsifiers are generally surfactants that combine the properties of both hydrophilic polar groups and hydrophobic (lipophilic) non-polar groups.

[0127] Regarding initiators, initiators are substances capable of initiating the polymerization reaction of monomers. For example, radical initiators are compounds that are easily decomposed into radicals (i.e., primary radicals) by heat and may be used to initiate the radical polymerization and copolymerization of ene and diene monomers.

[0128] For convenience of description, the above adhesive manufacturing method is defined by dividing the process into Step 1, Step 2, and Step 3 in accordance with the order of the described paragraphs. As will be understood by those skilled in the art, in the above methods of specific embodiments, the order of the described steps does not imply a strict order of execution and does not constitute any limitation on the implementation process; the specific order of execution of each step should be determined based on its function and possible underlying logic.

[0129] In step 1, water, an emulsifier, an initiator, and the constituent monomers of the polyacrylate polymer are mixed and stirred. The water and emulsifier are stirred and dispersed to form an emulsion; that is, the emulsifier forms micelles in the aqueous phase, solubilizing the monomers in most of the micelles. At elevated temperatures, the initiator initiates polymerization of the monomers inside the micelles to obtain a core layer seed emulsion. In step 2, the emulsifier and water are similarly dispersed to form an emulsion. At a certain pressure, the monomers enter the micelle reaction system. At elevated temperatures, the initiator enters the reaction system to initiate polymerization of the monomers. In step 2, a reaction takes place in the core layer seed emulsion of step 1, and the polyvinylidene fluoride polymer formed in step 2 is attached to the surface of the polyacrylate polymer of step 1, thereby forming a core-shell adhesive. In step 2, the dispersion polymerization and core formation mechanism of polyvinylidene fluoride belongs to the oligomer core formation mechanism, and at the same conversion rate, by increasing the content of initiator or emulsifier, smaller particle size of polyvinylidene fluoride-based latex particles can be obtained.

[0130] In step 2, since the constituent monomers of polyvinylidene fluoride polymers are in a gaseous state and do not easily enter micelles at normal pressure, pressurization is used to introduce the gaseous monomers into micelles, allowing the reaction to proceed efficiently.

[0131] Both steps 1 and 2 are carried out under heating conditions because a certain temperature is required for the initiator in steps 1 and 2 to be converted to have the function of initiating monomer polymerization.

[0132] At the same time, the mass of water in step 2 being equal to or greater than 0 means that water may or may not be added in step 2. It can be understood that if enough water is added in step 1, that is, if the water added in step 1 allows the solid content after the reaction of step 1 and step 2 to be within a predetermined range, then water may not be added in step 2. If not enough water is added in step 1, then a certain amount of water needs to be added in step 2 to adjust the solid content of the system, so as to prevent the viscosity from increasing after the reaction and slowing down the reaction rate.

[0133] As can be understood, the stirring rate in step 1 and step 2 is 1000 r / min-5000 r / min, for example, 1000 r / min, 2000 r / min, 3000 r / min, 4000 r / min, 5000 r / min, etc., but is not specifically limited, and the stirring time is 60 min±20 min. Under these stirring conditions, a uniformly emulsified prepolymer is obtained and used as a reserve.

[0134] In some embodiments, the ratio of the mass of the constituent monomers of the polyacrylate polymer to the mass of the constituent monomers of the polyvinylidene fluoride polymer is (2-100):1, and optionally (10-90):1.

[0135] In order to obtain a core-shell structure with a raspberry-like structure, the constituent monomer mass of the polyacrylate polymer of the core layer is made larger than the constituent monomer mass of the polyvinylidene fluoride polymer of the shell layer, so that the structural surface area of ​​the formed core layer is sufficiently large, i.e., the mass of the core layer is large and the structure is large, while the mass of the shell layer is small, making it difficult for the shell layer structure to completely cover the surface of the core layer; i.e., the polyvinylidene fluoride polymer is attached to the surface of the core layer without being connected, resulting in a low degree of crosslinking and a low degree of crystallinity of the polyvinylidene fluoride polymer, and thereby this core-shell structure reduces the crystallinity of the polyvinylidene fluoride polymer and improves the adhesive performance of the adhesive produced. Therefore, as shown in FIG. 2, the ratio of the constituent monomer mass of the polyacrylate polymer to the constituent monomer mass of the polyvinylidene fluoride polymer is (2 to 100):1, and may be, for example, 2:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc., and is not specifically limited.

[0136] In some embodiments, the step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate-based polymer, heating to react them, and obtaining a core layer seed emulsion includes a step of mixing and stirring water, an emulsifier, and constituent monomers of a polyacrylate-based polymer to obtain a core layer monomer pre-emulsion, and a step of adding an initiator after raising the temperature, stirring to react them, and obtaining a core layer seed emulsion after the reaction is complete.

[0137] To avoid explosive polymerization under heated conditions due to excessive initiator addition at once caused by adding the initiator before heating, the present application first mixes and stirs water, emulsifier, and constituent monomers of the polyacrylate polymer to obtain a core layer monomer pre-emulsion, and then adds the initiator after heating again and stirs to react, obtaining a core layer seed emulsion after the reaction is complete. It can be understood that the initiator is added in a slow dropwise manner, for example, at a dropwise rate of 10ml / min-500ml / min. It can also be understood that the initiator is dissolved in water and then added dropwise.

[0138] In some embodiments, the step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate-based polymer, heating to react them, and obtaining a core layer seed emulsion includes the steps of mixing and stirring water, an emulsifier, and constituent monomers of a polyacrylate-based polymer to obtain a core layer monomer pre-emulsion, and, after raising the temperature, adding initiators in lots, stirring to react them, and obtaining a core layer seed emulsion after the reaction is complete.

[0139] In order to avoid excessive dripping and explosive polymerization due to dripping of one batch of initiator, after the temperature is raised, the initiator is added in batches, and stirred to react, and after the reaction is completed, the core layer seed emulsion is obtained.At the same time, considering that the half-life of the initiator is constant, in order to avoid that the initiator dripped in the first batch cannot initiate the reaction of all the monomers, the initiator is dripped in batches, for example, the initiator added in the first batch, and after the decomposition is complete, a small amount of monomer remains, and a small amount of initiator is added, so that the remaining monomer can be fully reacted, and after the initiator is added, a small amount of monomer remains, but the remaining amount is greatly reduced.

[0140] In some embodiments, the step of adding initiator in batches after heating, stirring to react, and obtaining a core layer seed emulsion after the reaction is complete includes the steps of heating to 70°C±10°C, adding 1 / 3 of the initiator, stirring to react for 30 min±20 min, continuing to heat to 80°C±10°C, adding 2 / 3 of the initiator, continuing to heat to 90°C±10°C, stirring to react for 30 min±20 min, and obtaining a core layer seed emulsion after cooling.

[0141] The reaction temperature and reaction time affect the degree of polymerization of the crosslinking reaction, so that the monomers can react at the appropriate temperature and time to obtain a good polymer. In step 1, water, an emulsifier, and the constituent monomers of the polyacrylate polymer are mixed and stirred to obtain a core layer monomer pre-emulsion. The temperature is then raised to 70°C±10°C, one-third of the initiator is added, and the reaction is allowed to proceed with stirring for 30±20 minutes. The temperature is then continued to be raised to 80°C±10°C, two-thirds of the initiator is added, the temperature is continued to be raised to 90°C±10°C, and the reaction is allowed to proceed with stirring for 30±20 minutes. After cooling, a core layer seed emulsion is obtained. It is understood that the cooling temperature can be room temperature or 35°C-45°C, for example, 40°C, and is not specifically limited.

[0142] In some embodiments, the step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating to react and obtain a core layer seed emulsion includes the steps of: mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating to react and obtain a core layer seed emulsion; and adjusting the pH of the core layer seed emulsion to 6-8.

[0143] The resulting core layer structure polymer particles tend to aggregate and accumulate, which is detrimental to the subsequent production of a core-shell structure adhesive. To prevent this aggregation and sedimentation of the core layer structure polymer, a pH adjusting agent is added to the resulting core layer seed emulsion to uniformly disperse the particles in the core layer seed emulsion and stabilize the system. The pH range of the core layer seed emulsion is 6-8, and may be, for example, 6, 7, or 8, without any specific limitations. As can be understood, the present application does not limit the specific pH adjusting agent used; for example, aqueous ammonia may be used to adjust the pH.

[0144] In some embodiments, the step of adding an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating at reaction pressure to polymerize to obtain an adhesive includes the steps of placing the core layer seed emulsion in a reaction vessel, removing oxygen gas from the reaction vessel, adding the emulsifier, initiator, and constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, stirring, and heating to 75±10°C at reaction pressure to polymerize.

[0145] Considering that oxygen gas acts as a polymerization inhibitor and affects the polymerization reaction during polymerization, it is necessary to remove the oxygen gas from the reaction vessel. For example, before performing step 2, the oxygen gas from the reaction vessel may be removed. For example, nitrogen gas may be introduced into the reaction vessel to replace the oxygen gas. After the oxygen gas is removed, the emulsifier, initiator, and constituent monomers of the polyvinylidene fluoride polymer may be added to the reaction vessel, stirred, and heated to 75±10°C under reaction pressure to carry out the polymerization reaction.

[0146] In some embodiments, the step of placing the core layer seed emulsion in a reaction vessel, removing oxygen gas from the reaction vessel, adding an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, stirring, raising the temperature to 75±10°C under reaction pressure, and carrying out a polymerization reaction includes the steps of placing the core layer seed emulsion in a reaction vessel, adding an emulsifier and an initiator to the reaction vessel, stirring, removing oxygen gas from the reaction vessel, and further adding constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, raising the temperature to 75±10°C under reaction pressure, and carrying out a polymerization reaction.

[0147] Considering that first adding an emulsifier and an initiator to a reaction vessel and stirring, and then adding the constituent monomers of the polyvinylidene fluoride polymer can make the monomer emulsification more complete, the step of producing the shell layer may be to place the core layer seed emulsion in a reaction vessel, add an emulsifier and an initiator to the reaction vessel and stirring, remove oxygen gas from the reaction vessel, and then add the constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, raise the temperature to 75±10°C under reaction pressure, and carry out the polymerization reaction.

[0148] In some embodiments, the step of placing the core layer seed emulsion in a reaction vessel, removing oxygen gas from the reaction vessel, adding an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, stirring, raising the temperature to 75±10°C under reaction pressure, and carrying out a polymerization reaction includes the steps of placing the core layer seed emulsion in a reaction vessel, removing oxygen gas from the reaction vessel, adding an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, controlling the reaction pressure in the reaction vessel to 3.0 MPa to 4 MPa, stirring, raising the temperature to 75±10°C, carrying out a polymerization reaction, and when the pressure in the reaction vessel drops to 3.0 MPa, continuing to add constituent monomers of the polyvinylidene fluoride polymer and controlling the pressure in the reaction vessel to 3.0 MPa to 4 MPa until the reaction is completed.

[0149] Considering that the constituent monomers of polyvinylidene fluoride polymer are gases, during the polymerization reaction, the monomers in the reaction vessel are constantly consumed, causing the pressure in the reaction vessel to constantly decrease. Once the pressure drops to a certain level, it becomes difficult for the monomers to enter the solution system and reach the micelles to react. Therefore, it is necessary to control the pressure in the reaction vessel within a certain range to ensure that the monomers can effectively participate in the reaction. Therefore, the step of producing the shell layer may involve placing the core layer seed emulsion in the reaction vessel, removing oxygen gas from the reaction vessel, adding an emulsifier, an initiator, and the constituent monomers of polyvinylidene fluoride polymer to the reaction vessel, controlling the reaction pressure in the reaction vessel to 3.0 MPa to 4 MPa, stirring, raising the temperature to 75±10°C, and carrying out the polymerization reaction. When the pressure in the reaction vessel drops to 3.0 MPa, continuing to add the constituent monomers of polyvinylidene fluoride polymer, and controlling the pressure in the reaction vessel to 3.0 MPa to 4 MPa until the reaction is completed.

[0150] Considering that a pressure that is too low slows down the reaction rate, and a pressure that is too high increases energy consumption and makes the reaction violent, the reaction pressure is controlled within a range of 3.0 MPa to 4 MPa, and may be, for example, 3.0 MPa, 3.5 MPa, 4 MPa, etc., but is not specifically limited.

[0151] In some embodiments, in step 1, the mass of the emulsifier is 0.15% to 5% of the mass of the constituent monomers of the polyacrylate-based polymer, and the mass of the initiator is 0.15% to 1% of the mass of the constituent monomers of the polyacrylate-based polymer.

[0152] The amount of emulsifier used must be appropriate. Emulsifiers are an important component of emulsion polymerization, capable of converting incompatible oil (monomer)-water emulsions into fairly stable emulsions that are less likely to form stratified layers. In emulsion polymerization systems, emulsifiers have three main functions: 1) reducing surface tension and dispersing the monomer into fine droplets; 2) forming a protective layer on the droplet or colloidal particle surface, preventing aggregation and maintaining emulsion stability; and 3) forming micelles and solubilizing the monomer. Because the size and number of micelles depend on the amount of emulsifier used, the amount of emulsifier used directly affects the performance of the product. In step 1, the mass of the emulsifier is 0.15% to 5% of the mass of the constituent monomers of the polyacrylate polymer. Examples include 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 5%, but are not limited to these. The amount of initiator used has a significant effect on the polymerization rate and the performance of the product. If the amount of initiator used increases, the polymerization rate will increase, the polymerization reaction will become unstable, the molecular weight and yield will decrease, and the performance of the polymer will also deteriorate. In addition, if there is a shortage of initiator, the polymerization reaction will become difficult. Therefore, in step 1, the mass of the initiator is 0.15% to 1% of the mass of the constituent monomers of the polyacrylate polymer, and may be, for example, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., and is not specifically limited.

[0153] In some embodiments, in step 1, the emulsifier comprises an anionic emulsifier and the initiator comprises an azo initiator, an organic peroxide initiator, or an inorganic peroxide initiator.

[0154] Anionic emulsifiers are surface active materials whose active moieties tend to dissociate into negative ions when dissolved in water. They have one large organic anion and can react with bases to form salts. Depending on the structure of the negative ion-carrying moiety, they can be divided into three types: carboxylate, sulfonate, and sulfate.

[0155] Regarding the azo-based initiator, the azo-based initiator is a radical initiator whose molecular structure contains a nitrogen-nitrogen double bond.

[0156] Peroxide initiators are compounds containing a peroxy group (-OO-). When exposed to heat, the -OO- bond is broken and split into two corresponding radicals, thereby initiating monomer polymerization. They are classified into two types: inorganic peroxides and organic peroxides. Inorganic peroxide initiators include hydrogen peroxide, ammonium persulfate, or potassium persulfate, while organic peroxide initiators include benzoyl peroxide, benzoyl t-butyl peroxide, and methyl ethyl ketone peroxide.

[0157] An emulsifier is a substance that can form an emulsion of water. The present application does not limit the specific type or structure of the emulsifier, and any substance that can perform the above function and does not affect the reaction system can be used in the present application. For example, in step 1, the emulsifier used includes an anionic emulsifier. An initiator is a substance that can initiate the polymerization reaction of the monomer. The present application does not limit the specific type or structure of the initiator, and any substance that can perform the above function and does not affect the reaction system can be used in the present application. For example, in step 1, the initiator includes an azo initiator, an organic peroxide initiator, and an inorganic peroxide initiator.

[0158] In some embodiments, in step 1, the emulsifier includes at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium styrene sulfonate, and sodium vinyl sulfonate, and the initiator includes at least one of azobisisobutyronitrile, azobisisoheptanonitrile, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide.

[0159] The emulsifier is a substance capable of forming an emulsion of water. For example, the emulsifier used in step 1 includes at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, sodium styrenesulfonate, and sodium vinylsulfonate. That is, the emulsifier used may be one of the above, for example, preferably sodium dodecylbenzenesulfonate, or a mixture of two or more of the above. The initiator is a substance capable of initiating the polymerization reaction of the monomer. For example, the initiator used in step 1 includes at least one of azobisisobutyronitrile, azobisisoheptanonitrile, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide. That is, the initiator used may be one of the above, for example, preferably potassium persulfate, or a mixture of two or more of the above.

[0160] In some embodiments, in step 2, the mass of the emulsifier is 0.1% to 5% of the mass of the constituent monomers of the polyvinylidene fluoride polymer, and the mass of the initiator is 0.15% to 1% of the mass of the constituent monomers of the polyvinylidene fluoride polymer.

[0161] The amount of emulsifier used must be appropriate. Emulsifiers are an important component of emulsion polymerization, capable of converting incompatible oil (monomer)-water emulsions into fairly stable emulsions that are less likely to stratify. In emulsion polymerization systems, emulsifiers have three main functions: 1) reducing surface tension and dispersing the monomer into fine droplets; 2) forming a protective layer on the droplet or colloidal particle surface, preventing aggregation and maintaining emulsion stability; and 3) forming micelles and solubilizing the monomer. Because the size and number of micelles depend on the amount of emulsifier used, the amount of emulsifier used directly affects the performance of the product. In step 2, the mass of the emulsifier is 0.1% to 5% of the mass of the constituent monomers of the polyvinylidene fluoride polymer, and may be, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 5%, etc., but is not limited to this. The amount of initiator used has a significant effect on the polymerization rate and the performance of the product. If the amount of initiator used is increased, the polymerization rate will become faster, the polymerization reaction will become unstable, the molecular weight and yield will decrease, and the performance of the polymer will also deteriorate. In addition, if there is an insufficient amount of initiator, the polymerization reaction will become difficult. Therefore, in step 2, the mass of the initiator is 0.15% to 1% of the mass of the constituent monomers of the polyvinylidene fluoride polymer, and may be, for example, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., and is not specifically limited.

[0162] In some embodiments, in step 2, the emulsifier comprises a polyfluoro compound and the initiator comprises an organic peroxide initiator, an inorganic peroxide initiator.

[0163] An emulsifier is a substance that can form an emulsion of water. The specific type and structure of the emulsifier are not limited in this application, and any substance that can perform the above function and does not affect the reaction system can be used in this application. For example, in step 2, the emulsifier used includes a polyfluoro compound. An initiator is a substance that can initiate the polymerization reaction of the monomer. The specific type and structure of the initiator are not limited in this application, and any substance that can perform the above function and does not affect the reaction system can be used in this application. For example, in step 2, the initiator includes an organic peroxide initiator or an inorganic peroxide initiator. The initiator used is preferably an organic peroxide initiator, and the resulting polyvinylidene fluoride has high stability.

[0164] In some embodiments, in step 2, the emulsifier includes at least one of ammonium perfluoropolyether carboxylate, sodium perfluoropolyether carboxylate, and potassium perfluoropolyether carboxylate, and the initiator includes at least one of benzoyl peroxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate, di-normal-propyl peroxydicarbonate, diethyl peroxydicarbonate, and persulfates.

[0165] The emulsifier is a substance capable of forming an emulsion of water. For example, the emulsifier used in step 2 may include at least one of ammonium perfluoropolyether carboxylate, sodium perfluoropolyether carboxylate, and potassium perfluoropolyether carboxylate. The emulsifier may be one of the above, such as sodium perfluoropolyether carboxylate. The emulsifier may reduce the surface tension between droplets and prevent aggregation of the monomer liquid or latex particles. The emulsifier may also be a mixture of two or more of the above. The initiator is a substance capable of initiating the polymerization reaction of the monomer. For example, the initiator used in step 2 may include at least one of benzoyl peroxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diethyl peroxydicarbonate, and persulfates. The initiator may be one of the above, such as diisopropyl peroxydicarbonate, or a mixture of two or more of the above.

[0166] In some embodiments, the constituent monomers of the polyvinylidene fluoride polymer include vinylidene fluoride, or the constituent monomers of the polyvinylidene fluoride polymer include at least one of vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, tetrafluoropropylene, trifluoropropylene, perfluorobutene, tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, and vinyl fluoride.

[0167] Polyvinylidene fluoride polymer is a polymer containing vinylidene fluoride as a monomer, and the monomer of polyvinylidene fluoride polymer further contains, in addition to vinylidene fluoride, at least one of hexafluoropropylene, pentafluoropropylene, tetrafluoropropylene, trifluoropropylene, perfluorobutene, tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, and vinyl fluoride. That is, polyvinylidene fluoride polymer may be a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride and another fluorine-containing ethylene, and is not specifically limited.

[0168] In some embodiments, step 2 includes adding water, an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating at a reaction pressure to polymerize and obtain an adhesive, the step including adding water, a chain transfer agent, an emulsifier, an initiator, and constituent monomers of the polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating at a reaction pressure to polymerize and obtain an adhesive.

[0169] Chain transfer agents play a role in controlling the molecular weight distribution of the product in a polymerization reaction. Chain transfer is the process in which an active center in a chain polymerization reaction moves from a growing chain to another molecule. The number of active centers remains unchanged, but the growing polymer chain loses activity, forming a stable polymer and reducing the molecular weight of the product.

[0170] To effectively control the molecular weight of the reaction product, in step 2, water, chain transfer agent, emulsifier, initiator, and constituent monomers of polyvinylidene fluoride polymer are added to the core layer seed emulsion, stirred, and heated under reaction pressure to polymerize and obtain the adhesive. A chain transfer agent is added during the polymerization reaction to produce the appropriate adhesive.

[0171] In some embodiments, the weight of the chain transfer agent is 1% to 3% of the weight of the constituent monomers of the polyvinylidene fluoride polymer, and the chain transfer agent includes an alcohol-based compound, an ester-based compound, a ketone-based compound, and a halogenated alkane.

[0172] The mass of the chain transfer agent is 1% to 3% of the mass of the constituent monomers of the polyvinylidene fluoride polymer, and may be, for example, 1%, 1.5%, 2%, 2.5%, 3%, etc., and is not specifically limited. The chain transfer agent includes an alcohol-based compound, an ester-based compound, a ketone-based compound, and a halogenated alkane, and the specific type of the chain transfer agent is not specifically limited.

[0173] In some embodiments, the combined mass of the water in step 1 and the water in step 2 comprises 45%-60% of the mass of all materials in steps 1 and 2, and the water in steps 1 and 2 is deionized water.

[0174] Water acts as a dispersion medium, facilitating mass transfer and temperature control, and if too little or too much water is used, it is difficult to control the viscosity of the reaction system within a reasonable range. The total mass of water in step 1 and water in step 2 accounts for 45%-60% of the mass of all materials in steps 1 and 2, and may be, for example, 45%, 50%, 55%, 60%, etc., but is not specifically limited. At the same time, the water in steps 1 and 2 is deionized water to prevent impurities in the water from affecting the polymerization reaction.

[0175] The present application further provides a separator, which includes the above adhesive or an adhesive obtained by the above adhesive manufacturing method. The adhesive employs all the technical solutions of all the above embodiments, and therefore has at least all the beneficial effects of the technical solutions of the above embodiments, and will not be further described here.

[0176] The separator is coated with the adhesive, which can improve the adhesive performance between the electrode plate and the adhesive and solve the problem of openings in the conventional pre-cooling pressing process of the battery core.

[0177] The embodiments of the present application further provide an electrode assembly, which includes the above separator. The separator employs all the technical solutions of all the above embodiments, and therefore has at least all the beneficial effects of the technical solutions of the above embodiments, and will not be further described here.

[0178] The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator, and the adhesive is coated on the separator, thereby bonding the electrode plate and the separator together and improving the problem of openings between the electrode plate and the separator.

[0179] The embodiments of the present application further provide a battery cell, which includes the electrode assembly as described above. The electrode assembly employs all the technical solutions of all the embodiments, and therefore has at least all the beneficial effects of the technical solutions of the embodiments, and will not be further described here.

[0180] By applying the electrode assembly to a battery cell, the cycle performance of the large jig of the battery cell can be improved.

[0181] The embodiments of the present application further provide a battery, which includes the above-mentioned battery cell. The battery cell adopts all the technical solutions of all the above-mentioned embodiments, and therefore has at least all the beneficial effects of the technical solutions of the above-mentioned embodiments, and no further description will be given here.

[0182] The battery includes a battery module and a battery pack.

[0183] The embodiments of the present application further provide a power consumption device, which includes the above-mentioned battery cell or the above-mentioned battery, and the battery cell or the battery adopts all the technical solutions of all the above-mentioned embodiments, and therefore has at least all the beneficial effects of the technical solutions of the above-mentioned embodiments, and no further description will be given here.

[0184] The electrode assembly, battery cell, battery and power consuming device of the present application will be described below with appropriate reference to the drawings.

[0185] In one embodiment of the present application, an electrode assembly is provided.

[0186] Generally, the electrode assembly includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate, absorbing and releasing them. The electrolyte functions to conduct ions between the positive electrode plate and the negative electrode plate. The separator, located between the positive electrode plate and the negative electrode plate, primarily functions to prevent short-circuiting between the positive and negative electrodes and allows ions to pass through. The separator is the separator described above in this application.

[0187] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.

[0188] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0189] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0190] In some embodiments, when the electrode assembly is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art and used in lithium-ion batteries. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials usable as positive electrode active materials in batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0191] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0192] In some embodiments, the positive electrode film layer optionally further comprises a conductive agent, for example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0193] In some embodiments, a positive electrode plate can be manufactured as follows: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0194] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0195] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing surfaces of the negative electrode current collector.

[0196] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet may be copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer base material (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0197] In some embodiments, the negative electrode active material may be any negative electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of silicon, silicon oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of tin, tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0198] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0199] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0200] In some embodiments, the negative electrode membrane layer optionally further comprises other additives, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0201] In some embodiments, the negative electrode plate can be manufactured in the following manner: Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0202] The electrolyte serves to conduct ions between the positive and negative electrodes, and the present application does not specifically limit the type of electrolyte, which can be selected according to needs.

[0203] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0204] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0205] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0206] In some embodiments, the electrolyte solution may further optionally contain additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, or an additive that improves the high-temperature or low-temperature performance of the battery.

[0207] In some embodiments, the electrode assembly further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical and mechanical stability may be selected.

[0208] In some embodiments, the separator may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitation.

[0209] In some embodiments, the positive and negative electrodes and the separator can be fabricated into an electrode assembly by a winding or lamination process.

[0210] In some embodiments, the electrode assembly may include an outer casing, which may be used to package the electrode assembly and electrolyte.

[0211] In some embodiments, the exterior of the electrode assembly may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the electrode assembly may be a pouch, such as a bag-like pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0212] The present application does not particularly limit the shape of the electrode assembly, which may be cylindrical, rectangular, or any other shape. For example, Figure 5 shows an example of a battery cell 5 with a rectangular structure.

[0213] In some embodiments, referring to FIG. 6 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0214] In some embodiments, the electrode assemblies can be assembled into a battery module, and the number of electrode assemblies included in the battery module can be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0215] Fig. 7 shows an example of a battery module 4. Referring to Fig. 7, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, the battery cells 5 may be arranged in any other manner. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0216] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of battery cells 5 are accommodated in this accommodating space.

[0217] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0218] 8 and 9 show an example of a battery pack 1. Referring to FIGS. 8 and 9, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 can cover the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0219] The present application also provides a power consuming device, which includes at least one of the electrode assembly, battery module, or battery pack according to the present application. The electrode assembly, battery module, or battery pack may be used as a power source for the power consuming device or as 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, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0220] The power consumption device can be selected as an electrode assembly, a battery module, or a battery pack depending on its usage needs.

[0221] 10 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the electrode assembly of the power consuming device, a battery pack or battery module can be employed.

[0222] Another example of the device may be a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and employ an electrode assembly as a power source.

[0223] Example The following describes examples of the present application. The examples in the following description are examples and are used only to interpret the present application, and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out according to the techniques or conditions described in literature in the field or according to the product instructions. If the manufacturer of the reagents or equipment used is not specified, they are all ordinary products that can be purchased on the market.

[0224] Example 1 Adhesive manufacturing Step 1: Add 752.4g of methyl acrylate, 185.5g of acrylonitrile, and 62.1g of acrylamide into a 5L high-pressure reactor, with a molar ratio of 1:0.4:0.1; add 36g of sodium dodecyl sulfonate and 1.2kg of deionized water; thoroughly stir to disperse and emulsify; heat to 70℃; add initiator solution (0.6g of potassium persulfate dissolved in deionized water); stir and react for 30 minutes; continue to heat to 80℃; use a peristaltic pump to slowly add initiator solution (1.2g of potassium persulfate dissolved in deionized water); after the addition is complete, heat to 90℃; keep warm and react for 0.5 hours; cool to 40℃; obtain core layer seed emulsion; adjust pH to 7 with ammonia water; Step 2: Add 200g of deionized water, 1g of sodium perfluoropolyether carboxylate, and 0.85g of diisopropyl peroxydicarbonate into the high-pressure reactor, start stirring, evacuate, and replace the gas with nitrogen. Introduce vinylidene fluoride gas and hexafluoropropylene into the high-pressure reactor, increase the pressure in the high-pressure reactor to 3.5MPa, and increase the reaction temperature of the system to 75°C to start the polymerization reaction. When the pressure in the high-pressure reactor drops to 3.0MPa, continue to introduce vinylidene fluoride gas and hexafluoropropylene, and control the pressure in the high-pressure reactor to 3.0-3.5MPa. The amount of vinylidene fluoride and hexafluoropropylene involved in the reaction is 500g in total. When the pressure drops below 2MPa, stop the reaction, filter, and discharge to obtain a core-shell structured polymer adhesive.

[0225] Separator manufacturing A commercially available PP-PE copolymer microporous film with a thickness of 20 μm and an average pore diameter of 80 nm was used as the substrate. The adhesive prepared as described above was uniformly mixed with deionized water under stirring to obtain a slurry (solid content 20%). The slurry was uniformly applied to two surfaces of the substrate and dried to remove the solvent. The composition was coated on the substrate at a coating density of 1.0 g / m. 2 Thus, a separator was obtained.

[0226] Positive electrode plate manufacturing Polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), carbon black (a conductive agent), and N-methylpyrrolidone (NMP) were mixed in a mass ratio of 1.2:58.38:0.42:40 and thoroughly stirred to homogeneity, followed by preparation of a positive electrode slurry. This positive electrode slurry was prepared at a concentration of 200 g / m 2 The coating was uniformly applied onto an aluminum foil positive electrode current collector at a loading amount of 1000 ppm, and then the resulting product was dried, cold pressed, and slit to obtain a positive electrode plate.

[0227] Negative electrode plate manufacturing Artificial graphite, acetylene black as a conductive agent, styrene butadiene rubber (SBR) as an adhesive, and sodium carboxymethyl cellulose (CMC-Na) as a thickener were added to deionized water in a mass ratio of 96.2:1.0:1.6:1.2, and after thorough stirring to homogeneously mix, anode slurry (solid content 63%) was prepared. This anode slurry was prepared at 98 g / m 2 The coating was then dried, cold pressed and slit to obtain a negative electrode plate.

[0228] Electrolyte production At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and LiPF6 was dissolved in the mixed solvent to obtain an electrolyte solution, where the concentration of LiPF6 was 1 mol / L.

[0229] Battery cell manufacturing The positive electrode plate, separator, and negative electrode plate were stacked in this order, wound, and pre-press molded (the separator and electrode plate were bonded during this period) to obtain an electrode assembly. The electrode assembly was then placed in an outer casing, the prepared electrolyte solution was added, and after going through processes such as packaging, standing, chemical conversion, and aging, a battery cell was obtained.

[0230] The parameters (for example, as shown in Table 1) were changed in Example 1 to obtain the experimental data of Examples 2 to 11.

[0231] Comparative Example 1: Preparation steps of polyvinylidene fluoride polymer Add 200g of deionized water, 1g of sodium perfluoropolyether carboxylate, and 0.5g of diisopropyl peroxydicarbonate into the high-pressure reactor, start stirring, evacuate, replace the gas with nitrogen, introduce vinylidene fluoride and hexafluoropropylene gas into the high-pressure reactor, increase the pressure in the high-pressure reactor to 3.5MPa, increase the reaction temperature of the system to 75 ℃, start the polymerization reaction, when the pressure in the high-pressure reactor drops to 3.0MPa, continue to introduce vinylidene fluoride and hexafluoropropylene gas, control the pressure in the high-pressure reactor at 3.0-3.5MPa, add a total of 200g of vinylidene fluoride and hexafluoropropylene, and when the pressure drops below 2MPa, stop the reaction, filter and discharge.

[0232] Comparative Example 2: Steps for preparing a polymer obtained by polymerizing a first flexible monomer A three-neck flask was charged with 752.4 g of methyl acrylate, 36 g of sodium dodecyl sulfonate, and 1.2 kg of deionized water. The mixture was thoroughly stirred to disperse and emulsify the mixture. The temperature was then raised to 70°C, and an initiator solution (a solution prepared by dissolving 0.6 g of potassium persulfate in deionized water) was added. The mixture was stirred for 30 minutes to allow the reaction to proceed. The temperature was then raised to 80°C, and an initiator solution (a solution prepared by dissolving 1.2 g of potassium persulfate in 100 g of deionized water) was slowly added dropwise using a peristaltic pump. After the addition was complete, the temperature was raised to 90°C and the reaction was continued for 0.5 hours. The mixture was then cooled to 40°C, and the pH was adjusted to 7 with aqueous ammonia to terminate the reaction. The mixture was then filtered and discharged.

[0233] Comparative Example 3: Steps for preparing a polymer obtained by polymerizing a second polymerizable polar monomer Deionized water and a certain percentage of initiator were added to a three-neck flask equipped with a reflux condenser, thermometer, and magnetron stirrer. After uniform stirring at room temperature, the mixture was heated to the set temperature to promote decomposition of the initiator. Approximately half an hour after the temperature reached a constant level, a peristaltic pump was used to control the concentration of acrylonitrile in the polymerization system, and the monomer was added dropwise to the water to achieve the polymerization reaction. After the monomer addition was complete, the reaction was continued at a constant temperature for a certain period of time while stirring. After the reaction was completed, the three-neck flask was exposed to air and cooled to room temperature to terminate the reaction, which was then filtered and discharged.

[0234] Comparative Example 4: Steps for producing a polymer obtained by polymerizing a third polymerization molecular weight adjusting monomer First, 30-90 g of acrylamide monomer was added to 120 g of water to prepare an acrylamide solution. Then, 0.02-1 g of persulfate was dissolved in 30 g of water to prepare an initiator solution. 37.5 g of isopropyl alcohol solvent was added to a 250 mL four-neck reaction flask, opened, and stirred at 200 rpm. The temperature was raised to reflux, and the monomer solution and initiator solution were added dropwise continuously, controlling the addition rate and duration for 120 min. The reflux reaction was maintained for 2 h, after which the isopropyl alcohol was distilled off to obtain a polyacrylamide solution, which was then filtered and discharged.

[0235] Comparative Example 5: Mixing and polymerizing polyvinylidene fluoride and polyacrylate The polyvinylidene fluoride solution prepared in Comparative Example 1 and the polyacrylate solution prepared in Comparative Example 2 were mixed in a mass ratio of 1:1 and stirred uniformly to obtain a blend solution of polyvinylidene fluoride and polyacrylate, which was then filtered and discharged.

[0236] As shown in Tables 1 and 2, in Examples 2 to 4, 16 and 17, the ratios of the three types of polymers in the core layer were changed while the other conditions were kept unchanged, and in Examples 5 to 8 and 12 to 15, the masses of the core layer and shell layer were changed while the other conditions were kept unchanged.

[0237] As shown in Table 3, Comparative Example 1 is an adhesive obtained by producing a polyvinylidene fluoride polymer, Comparative Example 2 is an adhesive obtained by producing an acrylate-based polymer, Comparative Example 3 is an adhesive obtained by producing an acrylonitrile-based polymer, Comparative Example 4 is an adhesive obtained by producing an acrylamide-based polymer, and Comparative Example 5 is an adhesive obtained by producing a polymer obtained by mixing and polymerizing polyvinylidene fluoride and polyacrylate.

[0238] [Table 1]

[0239] [Table 2]

[0240] [Table 3]

[0241] Performance test: 1. Separator and electrode adhesion test step The battery plate and separator were stacked and placed in a heat press. The heat press parameters were set to 25°C, 10t, and 30s. A bonded separator / positive plate sample was then produced. The separator / positive plate sample was then cut into a 150 x 20mm rectangular spline. One side of the rectangular spline plate was attached to a steel plate with double-sided adhesive, and the separator and positive plate were separated by a 2cm length along one end of the rectangular spline to produce a test sample.

[0242] The steel plate was held horizontally and fixed in place by the lower fixture of a universal testing machine (Xieqiang Machinery Manufacturing (Shanghai) Co., Ltd., model CTM2100). The peeled end of the separator was fixed by the upper fixture of the universal testing machine, and a tensile machine was connected. The test conditions were set to a tensile rate of 20 mm / min and a horizontal tensile force of 10 cm. Once the tensile force stabilized, the tensile force value was recorded, and the ratio of the tensile force value to the sample width was used to determine the adhesive strength between the separator and the electrode plate.

[0243] 2. Battery core hardness test steps The battery core was placed on horizontal tables at both ends, and the width of the central openwork section was fixed at 12 cm. The battery core was then placed naturally flat, and the deviation of the center of the battery core from the horizontal reference line was measured to evaluate the hardness of the battery core. It was explained that the greater the deviation of the center of the battery core from the horizontal reference line, the worse the hardness of the battery core.

[0244] 3. Battery cycle performance test steps At 25°C, the batteries produced in Examples 1 to 17 and Comparative Examples 1 to 5 were charged at a constant current of 1 / 3 C to 3.8 V, then further charged at a constant voltage of 3.8 V until the current reached 0.05 C, left for 5 minutes, and further discharged at 1 / 3 C to 2.0 V. The resulting discharge capacity was designated as the initial capacity C0. The above steps were repeated for the same batteries, and the discharge capacity Cn of the batteries from the nth cycle onwards was simultaneously recorded. The battery capacity retention rate after each cycle, Pn, was calculated as (Cn / C0) × 100%. In other words, the battery capacity retention rate after 500 cycles can indicate differences in cycle performance.

[0245] [Table 4]

[0246] As shown in Table 4, the battery cores obtained using the adhesives in Examples 1 to 17 had good battery core hardness performance, while the battery cores obtained using the adhesives in Comparative Examples 1 to 5 had relatively poor hardness. It was explained that the adhesive performance of the adhesives in Examples 1 to 17 was superior to that of the adhesives in Comparative Examples 1 to 5. Furthermore, the adhesive strength performance and battery cycle performance between the separator and electrode plate in Examples 1 to 17 were superior to those between the separator and electrode plate and battery cycle performance in Comparative Examples 1 to 5. It was explained that when the adhesive performance of an adhesive is improved, the cycle performance of the battery can be effectively improved by using this adhesive in a battery separator.

[0247] The above is merely a preferred embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structural transformations made using the contents of the specification and drawings of the present application in accordance with the application concept of the present application, or direct or indirect applications in other related technical fields, are all included in the patent protection scope of the present application. [Explanation of symbols]

[0248] JPEG0007795557000005.jpg54139

Claims

1. An adhesive comprising: a core layer structure; and a shell layer structure provided on a surface of the core layer structure, the core layer structure comprising a polyacrylate-based polymer; and the shell layer structure comprising a polyvinylidene fluoride polymer; the constituent monomers of the polyacrylate polymer include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer; the first polymerizable flexible monomer is an acrylate-based monomer, the second polymerizable polar monomer is an acrylonitrile-based monomer, and the third polymerizable molecular weight-controlling monomer is an acrylamide-based monomer; The acrylate monomer includes at least one of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl 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, and 2-hydroxypropyl methacrylate; The acrylonitrile-based monomer includes at least one of acrylonitrile and methacrylonitrile, The acrylamide-based monomer includes at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide; the adhesive, wherein the molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.01-0.8):(0.01-0.15).

2. The adhesive according to claim 1 , wherein the shell layer structure includes a plurality of cases, the plurality of cases being spaced apart from one another on the surface of the core layer structure.

3. 3. The adhesive according to claim 1, wherein the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (2-100):

1.

4. 3. The adhesive according to claim 1, wherein the adhesive has a volume average particle diameter Dv50 of 0.5 μm to 50 μm.

5. 2. The adhesive of claim 1, wherein a molar ratio of the first polymerizable flexible monomer to the second polymerizable polar monomer to the third polymerizable molecular weight adjusting monomer is 1:(0.05-0.7):(0.05-0.12).

6. 3. The adhesive of claim 1 or 2, wherein the polyvinylidene fluoride polymer comprises at least one of vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-perfluorobutene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, or vinylidene fluoride-vinyl fluoride copolymer.

7. A method for producing the adhesive of claim 1, comprising: a step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating them to react with each other to obtain a core layer seed emulsion; adding water, an emulsifier, an initiator, and constituent monomers of a polyvinylidene fluoride polymer to the core layer seed emulsion, stirring, and heating under a reaction pressure to cause a polymerization reaction, thereby obtaining an adhesive having a core-shell structure.

8. 8. The method for producing an adhesive according to claim 7, wherein the ratio of the constituent monomer mass of the polyacrylate polymer to the constituent monomer mass of the polyvinylidene fluoride polymer is (2 to 100):

1.

9. In a step of mixing and stirring water, an emulsifier, an initiator, and constituent monomers of a polyacrylate polymer, and heating them to react with each other to obtain a core layer seed emulsion, a step of mixing and stirring water, an emulsifier, and constituent monomers of a polyacrylate polymer to obtain a core layer monomer pre-emulsion; 8. The method for producing an adhesive according to claim 7, further comprising the steps of: after the temperature is raised, adding an initiator in batches, stirring to cause a reaction, and obtaining a core layer seed emulsion after the reaction is completed.

10. The constituent monomer of the polyvinylidene fluoride polymer includes vinylidene fluoride, Alternatively, the method for producing an adhesive according to claim 7, wherein constituent monomers of the polyvinylidene fluoride polymer include at least one of vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, tetrafluoropropylene, trifluoropropylene, perfluorobutene, tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, and vinyl fluoride.

11. A separator comprising the adhesive of claim 1.

12. An electrode assembly comprising the separator of claim 11.

13. A battery cell comprising the electrode assembly of claim 12.

14. A battery comprising the battery cell of claim 13.

15. A power consuming device comprising a battery cell according to claim 13 or a battery according to claim 14.

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