JP7795557B2 - Adhesive and manufacturing method thereof, separator, electrode assembly, battery cell, battery and power consumption device - Google Patents

Description

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

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

With the rapid increase in portable electronic devices and electric vehicles, the demand for power batteries is also constantly increasing. At this time, the electrochemical performance of batteries is also attracting increasing attention.

Currently, the battery core of batteries has an opening problem, meaning that gaps easily form between the electrode plates and the separator, which results in poor battery cycling performance.

The primary objective of this application is to provide an adhesive that improves the adhesive strength between the separator and the electrode plate, thereby improving the cycle performance of the battery.

To achieve the above object, the present application provides an adhesive, which includes a core layer structure and a shell layer structure provided on the 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.

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-based polymer, and the shell layer structure comprises a polyvinylidene fluoride polymer. Since polyvinylidene fluoride is a homopolymer with a crystallinity of approximately 50% and insufficient adhesive strength, the present application coats the polyacrylate-based polymer with 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. This adhesive improves the adhesive strength between the separator and the electrode plate.

Optionally, the shell layer structure includes a plurality of cases, the cases being spaced apart on the surface of the core layer structure.

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. In other words, the polyvinylidene fluoride polymer cases 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 composed of multiple cases, with gaps between adjacent cases, exposing the surface of the core layer structure at these 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. Therefore, the core layer structure exposed between the cases also enhances its adhesive performance. Furthermore, the raspberry-like core-shell structure has a larger specific surface area than a core layer structure completely coated with a shell layer. Thus, the adhesive surface structure can perform a greater adhesive function.

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

To achieve the low-crosslinking shell layer structure mentioned above, 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, leaving some of the structure exposed on the surface of the core layer structure, thereby achieving 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 (2-100):1. In the above (2-100):1 range, values include the minimum and maximum values within this range, as well as values between these 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.

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

In the above (10-90):1 range, the values include the minimum and maximum values of this range, as well as 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 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

Optionally, the volume average particle diameter Dv50 of the adhesive is 0.5 μm-50 μm, and optionally 7 μm-8 μm.

Theoretically, the volume average particle diameter Dv50 of the adhesive in this application can be less than 0.5 μm or more than 50 μm. However, considering that the adhesive in this 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 likely clog the pores in 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. Because 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. Within the 0.5 μm-50 μm range, values include the minimum and maximum values within this range, as well as values between these minimum and maximum values. Specific examples include, but are not limited to, the point values in the examples, as well as 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.

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

When the volume average particle diameter Dv50 of the adhesive is 7 μm-8 μm, the resulting separator has excellent performance. Within the 7 μm-8 μm range, values include the minimum and maximum values within this range, as well as values between these 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.

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.

The constituent monomers of the polyacrylate polymer in this application include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer. By crosslinking the three types of monomers to obtain a polymer, the molecular weight and glass transition temperature of the polymer can be controlled, thereby improving the adhesive performance of the adhesive.

Optionally, 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), and optionally 1:(0.05-0.7):(0.05-0.12).

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 effect. In the above 1:(0.01-0.8):(0.01-0.15), the values include the minimum and maximum values of this range, and each value between such minimum and maximum values. Specific examples include the point values in the examples and 1:0. Examples include, but are not limited to, 1:0.01:0.01, 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.

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

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 exhibits excellent adhesive properties. Within the range of 1:(0.05-0.7):(0.05-0.12), the values include the minimum and maximum values within this range, as well as values between these 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.

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.

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 prone to forming hydrogen bonds, improving adhesive properties. By including an ester bond in the structure of the first polymerizable flexible monomer, a cyano group in the structure of the second polymerizable polar monomer, and 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.

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.

Acrylate monomers can improve the swelling resistance of polymers, and as flexible monomer segments in the molecular segments, they can adjust the polymer's glass transition temperature, improving the toughness of the adhesive when applied, thereby contributing to good adhesive properties.

Acrylonitrile-based monomers contain highly polar cyano groups, which improve ionic conductivity and contribute to improved adhesion.

Acrylamide-based monomers not only help regulate molecular weight, but also have relatively good adhesive properties.

The polymers produced using the above three types of monomers can control the polymer's molecular weight and glass transition temperature, thereby improving the adhesive performance of the adhesive.

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.

Acrylate monomers contribute to improving the adhesive properties of the adhesive. The acrylate monomers 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 a polyacrylate polymer may include one or more of the above acrylate monomers; there are no specific limitations.

Acrylonitrile-based monomers contribute to improving the adhesive properties of the adhesive, and the acrylonitrile-based monomers include 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 multiple of the above acrylonitrile-based monomers; there are no specific limitations.

Acrylamide-based monomers contribute to improving the adhesive properties of adhesives, and the acrylamide-based monomers include at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide. In other words, the constituent monomers of the polyacrylate polymer may include one of the above acrylamide-based monomers or multiple of the above acrylamide-based monomers; there are no specific limitations.

Optionally, the polyvinylidene fluoride polymer 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, or vinylidene fluoride-vinyl fluoride copolymer.

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, making them commonly used in lithium-ion battery separators.

The polyvinylidene fluoride polymer used in this 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.

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.

In this application, a polyacrylate polymer for the core layer is first obtained using an emulsion polymerization method, and then a polyvinylidene fluoride polymer is produced using an emulsion polymerization method to obtain a shell layer on the surface of the core layer structure, ultimately forming an adhesive with a core-shell structure.

Optionally, 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 to 100):1, and optionally (10 to 90):1.

To obtain a raspberry-shaped core-shell 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. This results in a sufficiently large structural surface area for the core layer, i.e., the mass of the core layer is large and the structure is large, while the mass of the shell layer is small. This makes 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 connecting, resulting in a low degree of crosslinking and a low degree of crystallinity for the polyvinylidene fluoride polymer. This core-shell structure reduces the crystallinity of the polyvinylidene fluoride polymer, improving the adhesive performance of the resulting adhesive. Therefore, as shown in Figure 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 range, the value includes the minimum and maximum values of this range, as well as 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.

Optionally, 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 (10 to 90):1.

In the above (10-90):1 range, the values include the minimum and maximum values of this range, as well as 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 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

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 cause a reaction, and after the reaction is completed, a core layer seed emulsion is obtained.

To avoid explosive polymerization under heated conditions due to excessive initiator being added all at once 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 dripping caused by adding one lot of initiator dropwise, which could lead to explosive polymerization, the initiator is added in lots after the temperature is raised, stirred, and reacted, and the core layer seed emulsion is obtained after the reaction is complete.

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.

Polyvinylidene fluoride polymer is a polymer containing vinylidene fluoride as a monomer. The monomers of polyvinylidene fluoride polymer include, 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; there are no specific limitations.

The present application provides a separator, which includes the above-described adhesive or an adhesive produced by the above-described adhesive production method.

The separator is coated with the above adhesive, which improves the adhesive performance between the electrode plate and the adhesive and alleviates the problem of openings in the conventional battery core pre-cooling pressing process.

An embodiment of the present application provides an electrode assembly, which includes the separator described above.

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

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

By applying the above electrode assembly to a battery cell, the cycle performance of the battery cell's large jig can be improved.

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

An embodiment of the present application provides a power consumption device, which includes the above-described battery cell or the above-described battery.

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.
1 is a flow chart of a method for manufacturing an adhesive according to an embodiment of the present application. 1 is a flow chart of a method for manufacturing an adhesive according to an embodiment of the present application. 1 is a scanning electron microscope view of an adhesive according to an example of the present application. FIG. 4 is a magnified scanning electron microscope view of the adhesive in FIG. 3 . 1 is a schematic diagram of an electrode assembly according to an embodiment of the present application. FIG. 6 is an exploded view of the electrode assembly according to the embodiment of the present application shown in FIG. 5. 1 is a schematic diagram of a battery module according to an embodiment of the present application; 1 is a schematic diagram of a battery pack according to an embodiment of the present application. FIG. 9 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 8. 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;

The following clearly and completely describes the technical solutions in the embodiments of this application, in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only some of the embodiments of this application, not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without the need for creative efforts fall within the scope of protection of this application.

Hereinafter, with appropriate reference to the drawings, detailed embodiments of the present application will be described in detail, specifically disclosing the adhesive and its manufacturing method, as well as separators, electrode assemblies, battery cells, batteries, and power consumption devices each including the adhesive. 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. The drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and do not limit the subject matter described in the claims.

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 endpoints, and any combination is possible; that is, any lower limit can 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 possible. Furthermore, if 1 and 2 are listed as minimum range values and 3, 4, and 5 are listed as maximum range values, the following ranges are all possible: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, a numerical range "a-b" 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" indicates that this specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Furthermore, 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.

Unless otherwise stated, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

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.

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 may include 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; 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.

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.

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).

The battery core of the battery has an opening problem, meaning that gaps easily form between the plates and the separator, which reduces battery cycling performance.

For example, polyvinylidene fluoride, the most commonly used adhesive, is widely used in separators. However, at present, the price of polyvinylidene fluoride is rising rapidly, resulting in tight market supply. Coating the surface of lithium battery separators with polyvinylidene fluoride polymer can partially solve the separator's high-temperature shrinkage problem. Cold pressing is performed after winding the battery core. However, typical polyvinylidene fluoride is a homopolymer with a crystallinity of approximately 50%, which means it lacks adhesion to the positive and negative electrodes, often causing the battery core to open up. This means it cannot meet the performance requirements of coated separators for power lithium-ion batteries.

That is, coating the surface of a lithium battery separator with polyvinylidene fluoride polymer can partially solve the separator's high-temperature shrinkage problem. After winding the battery core, cold pressing is performed. However, typical polyvinylidene fluoride is a homopolymer with a crystallinity of approximately 50%, which means it lacks adhesive strength with the positive and negative electrodes, 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 reducing the battery core's cycle performance.

A battery core is formed by bonding positive and negative electrode plates and a separator together. The battery core has a certain hardness; that is, the bonded positive and negative electrode plates and separator are tightly supported by each other, forming a structure with a certain thickness. A structure with a certain thickness also has a certain hardness. The negative electrode expands during charging and discharging. If the adhesive strength is weak, gaps form between the positive and negative electrode plates and the separator, preventing the positive and negative electrode plates and separator from being tightly supported by each other. This causes the battery core to loosen and its hardness to decrease. This results in poor power performance of the battery core, including reduced rate performance and poor cycle performance. For example, in electric vehicles, loosening the battery core can slow down the battery's charging speed and reduce its cycle performance, directly shortening battery life and requiring frequent battery replacement, increasing the cost of electric vehicles for consumers.

Based on this, the present application provides an adhesive, which includes a core layer structure and a shell layer structure provided on the 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.

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

A core-shell structure consists of a central core and a shell covering the outer layer.

A core layer structure is a structure that is located inside a core-shell structure and is covered by an outer shell.

The shell layer structure is the structure located on the outside of the core-shell structure and covering the surface of the core layer structure.

Polyacrylate polymers are polymers made from acrylate monomers.

Polyvinylidene fluoride polymer is a polymer made from vinylidene fluoride as a monomer.

This application coats a polyacrylate-based polymer with a polyvinylidene fluoride polymer to obtain a core-shell structured adhesive, thereby improving the crystallinity of the polyvinylidene fluoride polymer in the core-shell structured adhesive and improving the adhesive performance of the core-shell structured adhesive, which in turn improves the adhesive strength between the separator and the electrode plate. The adhesive of this application has good adhesive performance, preventing separation between the electrode plate and separator during electrode plate expansion, maintaining good hardness of the battery core, and improving the dynamic and cycling performance of the battery core.

Theoretically, as the degree of crystallinity increases, the molecular chain arrangement becomes tighter and more orderly, the void ratio decreases, the intermolecular interaction force increases, and segment movement becomes more difficult. This improves the polymer's yield stress, strength, modulus, and hardness, but also reduces the elongation at break and impact toughness. Clearly, crystallization makes the polymer harder and more brittle, and its adhesive performance also decreases.

This application coats a polyacrylate-based polymer with a polyvinylidene fluoride polymer. Compared to pure polyvinylidene fluoride, the core-shell structure of this adhesive reduces the overall crystallinity and improves adhesive performance. Using this core-shell structure adhesive improves 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 disorder of the adhesive's molecular structure, increasing the porosity and further improving the adhesive's liquid wettability. Coating this adhesive on a separator improves the separator's electrolyte wettability, which is advantageous for improving the battery's cycle performance.

In some embodiments, the shell layer structure includes multiple cases, which are spaced apart on the surface of the core layer structure.

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. In other words, 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 between adjacent casings, exposing the surface of the core layer structure at these 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. Therefore, the core layer structure exposed between the casings can also enhance its adhesive performance. Furthermore, the raspberry-like core-shell structure has a larger specific surface area than a core layer structure completely coated with a shell layer. Thus, the adhesive surface structure can perform a greater adhesive function.

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 crosslinking reactions, and the bond between the core layer and shell layer is primarily an ionic bonding mechanism, with the constituent monomers of the polyvinylidene fluoride polymer adsorbed onto the constituent monomers of the polyacrylate-based polymer through the effects of ionic bonds, van der Waals forces, etc.

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

The mass ratio test method is as follows: In the adhesive manufacturing process, the mass of the monomer added during the reaction 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 polyacrylate polymer to polyvinylidene fluoride polymer is m:n.

To achieve the low-crosslinking shell layer structure mentioned above, 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, leaving some of the structure exposed on the surface of the core layer structure, thereby achieving 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 (2-100):1. In the above (2-100):1 range, values include the minimum and maximum values within this range, as well as values between these 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.

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

In the above (10-90):1 range, the values include the minimum and maximum values of this range, as well as 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 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, etc.

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

The volume average particle size Dv50 of an adhesive can be tested using methods known in the art. For example, see GB/T 19077-2016, where characterization tests are performed using a Malvern Mastersizer, such as a Malvern Mastersizer-3000.

Theoretically, the volume average particle diameter Dv50 of the adhesive in this application can be less than 0.5 μm or more than 50 μm. However, considering that the adhesive in this 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 likely clog the pores in 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. Because 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. Within the 0.5 μm-50 μm range, values include the minimum and maximum values within this range, as well as values between these minimum and maximum values. Specific examples include, but are not limited to, the point values in the examples, as well as 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.

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

When the volume average particle diameter Dv50 of the adhesive is 7 μm-8 μm, the resulting separator has excellent performance. Within the 7 μm-8 μm range, values include the minimum and maximum values within this range, as well as values between these 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.

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.

Regarding flexible monomers, the homopolymer glass transition temperature of flexible monomers is lower than that of rigid monomers. Flexible monomers have a certain degree of flexibility relative to rigid groups, allowing the segments to move freely. The flexible monomer segments adjust the polymer's glass transition temperature and improve the toughness of the adhesive when applied, contributing to good adhesive properties.

A polar monomer is a monomer that contains a polar group, and polar monomers contribute to improving the adhesive properties of the polymer.

Molecular weight adjusting monomers are monomers that participate in crosslinking reactions and are used to adjust the molecular weight of the polymer. Ensuring that the molecular weight of the adhesive is within a certain range contributes to improved adhesive properties.

The constituent monomers of the polyacrylate polymer in this application include a first polymerizable flexible monomer, a second polymerizable polar monomer, and a third polymerizable molecular weight adjusting monomer. By crosslinking the three types of monomers to obtain a polymer, the molecular weight and glass transition temperature of the polymer can be controlled, thereby improving the adhesive performance of the adhesive.

The softening point of the modified polymer is lower than that of pure polyvinylidene fluoride polymers, and when the battery core is pre-cooled and 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 the gap, effectively connecting the electrode plate and the separator, and the adhesive is less likely to come out of the gap. Even when the electrode plate expands, the adhesive retains its toughness and can effectively connect the two even during expansion, allowing the adhesive to fully demonstrate its adhesive performance, further contributing to improving the dynamic performance of the battery and the cycle performance of the large jig.

The softening point here refers to the temperature at which a substance softens. It is related not only to the structure of the polymer but also to its molecular weight. In this application, the softening point of the polymer is improved by adjusting the molecular weight of the polymer using a third polymerization molecular weight adjusting monomer.

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 by 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 proposal 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. Battery cores using the adhesive of this application have relatively good performance retention under the test conditions of the large jig. It is explained that the battery core obtained using the adhesive of this proposal has excellent deformation retention. When the battery cores are assembled to form a battery, the battery core is less likely to deform, which saves space in the battery for installing the battery core, thereby making it possible to reduce the volume of the battery. Therefore, if the battery core is prone to deformation, it will press on structures near the battery core, and to avoid this phenomenon, a larger space is required to accommodate the deformed battery core; that is, space in the battery must be reserved to accommodate the deformed part of the battery core, which occupies more space within the battery.

At the same time, the good cycle performance of the battery core's large jig also explains the good cycle performance of the battery core. For example, if the battery core expands, the gap between the electrode plates and the separator becomes larger, lengthening the path for lithium ions to pass through the positive and negative electrodes, resulting in poor cycle performance.

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

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 manufacturing process. The number of moles of each type of monomer is calculated by dividing the mass of each type of monomer by its molecular weight. If the number of moles of the first flexible monomer is defined as a, the number of moles of the second polar monomer is defined as b, and the number of moles of the third molecular weight adjusting monomer is defined as c, then the molar ratio of the first flexible monomer, the second polar monomer, and the third molecular weight adjusting monomer is a:b:c.

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 effect. In the above 1:(0.01-0.8):(0.01-0.15), the values include the minimum and maximum values of this range, and each value between such minimum and maximum values. Specific examples include the point values in the examples and 1:0. Examples include, but are not limited to, 1:0.01:0.01, 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.

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

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 exhibits excellent adhesive properties. Within the range of 1:(0.05-0.7):(0.05-0.12), the values include the minimum and maximum values within this range, as well as values between these 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.

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 control monomer contains an amide bond (-CO-NH-).

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 prone to forming hydrogen bonds, improving adhesive properties. By including an ester bond in the structure of the first polymerizable flexible monomer, a cyano group in the structure of the second polymerizable polar monomer, and 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.

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.

Acrylate monomers can improve the swelling resistance of polymers, and as flexible monomer segments in the molecular segments, they can adjust the polymer's glass transition temperature, improving the toughness of the adhesive when applied, thereby contributing to good adhesive properties.

Acrylonitrile-based monomers contain highly polar cyano groups, which improve ionic conductivity and contribute to improved adhesion.

Acrylamide-based monomers not only help regulate molecular weight, but also have relatively good adhesive properties.

The polymers produced using the above three types of monomers can control the polymer's molecular weight and glass transition temperature, thereby improving the adhesive performance of the adhesive.

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.

Acrylate monomers contribute to improving the adhesive properties of the adhesive. The acrylate monomers 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 a polyacrylate polymer may include one or more of the above acrylate monomers; there are no specific limitations.

Acrylonitrile-based monomers contribute to improving the adhesive properties of the adhesive, and the acrylonitrile-based monomers include 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 multiple of the above acrylonitrile-based monomers; there are no specific limitations.

Acrylamide-based monomers contribute to improving the adhesive properties of adhesives, and the acrylamide-based monomers include at least one of acrylamide, N-methylolacrylamide, and N-butoxymethacrylamide. In other words, the constituent monomers of the polyacrylate polymer may include one of the above acrylamide-based monomers or multiple of the above acrylamide-based monomers; there are no specific limitations.

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.

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, making them commonly used in lithium-ion battery separators.

The polyvinylidene fluoride polymer used in this 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.

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.

In this application, a polyacrylate polymer for the core layer is first obtained using an emulsion polymerization method, and then a polyvinylidene fluoride polymer is produced using an emulsion polymerization method to obtain a shell layer on the surface of the core layer structure, ultimately forming an adhesive with a core-shell structure.

Regarding emulsion polymerization, emulsion polymerization is a process in which monomers are dispersed in water with an emulsifier through mechanical stirring to form an emulsion, and then an initiator is added to start the monomer polymerization.

A core-shell structure consists of a central core and a shell covering the outer layer.

Seed emulsion is made by first producing seed latex using a small amount of monomers through a conventional emulsion polymerization method, and then adding a small amount of seed latex to the official emulsion polymerization recipe. The polymerization reaction takes place with the seed emulsion latex particles as the core, causing the latex particles to continuously grow.

A pre-emulsion is a solution obtained by pre-emulsifying monomers. Emulsification involves uniformly dispersing one liquid into another incompatible liquid in the form of extremely tiny 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 through the action of the emulsifier.

Regarding emulsifiers, they 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.

Regarding initiators, an initiator is a substance that can initiate a polymerization reaction of monomers. For example, a radical initiator is a compound that is easily decomposed into radicals (i.e., primary radicals) by heat, and may be used to initiate the radical polymerization and copolymerization reactions of ene and diene monomers.

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

In step 1, water, emulsifier, initiator, and constituent monomers of the polyacrylate polymer are mixed and stirred. The water and emulsifier are stirred and dispersed to form an emulsion. 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 constant pressure, the monomers enter the micelle reaction system. At elevated temperatures, the initiator enters the reaction system to initiate the polymerization reaction of the monomers. In step 2, a reaction occurs 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, increasing the content of initiator or emulsifier can result in smaller polyvinylidene fluoride-based latex particles.

In step 2, since the constituent monomers of polyvinylidene fluoride polymer 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.

Both steps 1 and 2 are carried out under heated conditions because a certain temperature is required to convert the initiator in these steps so that it has the ability to initiate monomer polymerization.

At the same time, if the mass of water in step 2 is 0 or more, this means that water may or may not be added in step 2. As can be understood, if sufficient water is added in step 1, i.e., if the water added in step 1 allows the solids content after the completion of the reactions in steps 1 and 2 to fall within a predetermined range, then water does not need to be added in step 2. However, if insufficient water is added in step 1, a certain amount of water must be added in step 2 to adjust the solids content of the system so as to prevent the viscosity from increasing after the reaction and slowing down the reaction rate.

As can be understood, the stirring rate in steps 1 and 2 is 1000 r/min-5000 r/min, and may be, for example, 1000 r/min, 2000 r/min, 3000 r/min, 4000 r/min, 5000 r/min, etc., without specific limitations, and the stirring time is 60 min ± 20 min. Under these stirring conditions, a uniformly emulsified prepolymer is obtained and used as a reserve.

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

To obtain a raspberry-shaped core-shell 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. This results in a sufficiently large structural surface area for the core layer, i.e., the mass of the core layer is large and the structure is large, while the mass of the shell layer is small. This makes 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 connecting, resulting in a low degree of crosslinking and a low degree of crystallinity for the polyvinylidene fluoride polymer. This core-shell structure reduces the crystallinity of the polyvinylidene fluoride polymer, improving the adhesive performance of the resulting adhesive. Therefore, as shown in Figure 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., but is not specifically limited.

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, and constituent monomers of a polyacrylate polymer to obtain a core layer monomer pre-emulsion, and adding an initiator after heating, stirring to react, and obtaining a core layer seed emulsion after the reaction is complete.

To avoid explosive polymerization under heated conditions due to excessive initiator addition all 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. After heating again, the initiator is added and stirred to react, obtaining a core layer seed emulsion after the reaction is complete. It is understood that the initiator is added slowly dropwise, for example, at a rate of 10 ml/min-500 ml/min. It is also understood that the initiator is dissolved in water and then added dropwise.

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

To avoid excessive addition and explosive polymerization caused by adding one batch of initiator dropwise, the initiator is added in batches after the temperature is raised, and the mixture is stirred to react, yielding a core layer seed emulsion after the reaction is complete. At the same time, given that the half-life of the initiator is constant, to avoid the first batch of initiator not being able to initiate all of the monomer reactions, the initiator is added dropwise in batches, for example, the initiator added in the first batch. After decomposition is complete, a small amount of monomer remains, and a small amount of initiator is then replenished to allow the remaining monomer to react as fully as possible. Even after the initiator is replenished, a small amount of monomer remains, but the amount remaining is significantly reduced.

In some embodiments, the step of adding the initiator in lots 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 for 30 minutes±20 minutes to react, continuing to heat to 80°C±10°C, adding 2/3 of the initiator, continuing to heat to 90°C±10°C, stirring for 30 minutes±20 minutes to react, and obtaining a core layer seed emulsion after cooling.

The reaction temperature and reaction time affect the degree of polymerization of the crosslinking reaction. To ensure that the monomers are reacted at the appropriate temperature and time to obtain a good polymer, in step 1, water, 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 mixture is stirred for 30±20 minutes to react. 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 mixture is stirred for 30±20 minutes to react. After cooling, the 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.

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.

The resulting core layer structure polymer particles tend to aggregate and sediment, 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, uniformly dispersing the particles in the core layer seed emulsion and stabilizing the system. The pH range of the core layer seed emulsion is 6-8, and may be, for example, pH 6, pH 7, pH 8, etc., 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.

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 and obtain an adhesive includes 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.

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 by, for example, replacing the oxygen gas by introducing nitrogen gas into the reaction vessel. 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.

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, 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.

Considering that first adding an emulsifier and initiator to a reaction vessel and stirring, and then adding the constituent monomers of the polyvinylidene fluoride polymer, can result in more complete emulsification of the monomers, the step of producing the shell layer may involve placing the core layer seed emulsion in a reaction vessel, adding an emulsifier and initiator to the reaction vessel and stirring, removing oxygen gas from the reaction vessel, and then adding the constituent monomers of the polyvinylidene fluoride polymer to the reaction vessel, raising the temperature to 75±10°C under reaction pressure, and carrying out the polymerization reaction.

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, 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 conducting 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, 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, conducting 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.

Considering that the constituent monomers of polyvinylidene fluoride polymer are gases, the monomers in the reaction vessel are constantly consumed during the polymerization reaction, 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 are effectively involved 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 the emulsifier, initiator, and 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 conducting 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.

Considering that a pressure that is too low will slow the reaction rate, and a pressure that is too high will consume a lot of energy and cause the reaction to become violent, the reaction pressure control range is 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.

In some embodiments, in step 1, the weight of the emulsifier is 0.15% to 5% of the weight of the constituent monomers of the polyacrylate polymer, and the weight of the initiator is 0.15% to 1% of the weight of the constituent monomers of the polyacrylate polymer.

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 surface of droplets or colloidal particles, 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 there are no specific limitations. The amount of initiator used has a significant impact on the polymerization rate and product performance. 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 polymer performance will deteriorate. In addition, an insufficient amount of initiator will make the polymerization reaction 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.

In some embodiments, in step 1, the emulsifier includes an anionic emulsifier, and the initiator includes an azo initiator, an organic peroxide initiator, or an inorganic peroxide initiator.

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

Regarding azo initiators, azo initiators are radical initiators whose molecular structure contains a nitrogen-nitrogen double bond.

Peroxide initiators are compounds containing a peroxy group (-O-O-). When exposed to heat, the -O-O- bond is broken, splitting into two corresponding radicals and initiating monomer polymerization. They are called peroxide initiators. Peroxides are divided into two types: inorganic and organic. 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.

An emulsifier is a substance that can form an emulsion of water. This application does not limit the specific type or structure of the emulsifier; any substance that can perform the above function and does not affect the reaction system is applicable to this 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 monomers. This application does not limit the specific type or structure of the initiator; any substance that can perform the above function and does not affect the reaction system is applicable to this application. For example, in step 1, the initiator includes an azo initiator, organic peroxide initiator, and inorganic peroxide initiator.

In some embodiments, in step 1, the emulsifier includes at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, sodium styrenesulfonate, 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.

An emulsifier is a substance that can form 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 can be one of the above. For example, the emulsifier is preferably sodium dodecylbenzenesulfonate, or a mixture of two or more of the above. An initiator is a substance that can initiate the polymerization reaction of monomers. 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 can be one of the above. For example, the initiator is preferably potassium persulfate, or a mixture of two or more of the above.

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

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 surface of droplets or colloidal particles, 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., without specific limitations. The amount of initiator used has a significant effect on the polymerization rate and product performance. If the amount of initiator used is increased, the polymerization rate will increase, the polymerization reaction will become unstable, the molecular weight and yield will decrease, and the polymer performance will deteriorate. In addition, an insufficient amount of initiator will make the polymerization reaction 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.

In some embodiments, in step 2, the emulsifier includes a polyfluoro compound and the initiator includes an organic peroxide initiator or an inorganic peroxide initiator.

An emulsifier is a substance that can form an emulsion of water. This application does not limit the specific type or structure of the emulsifier; 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. This application does not limit the specific type or structure of the initiator; 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, as the resulting polyvinylidene fluoride has high stability.

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.

An emulsifier is a substance that can form an emulsion of water. For example, the emulsifier used in step 2 includes at least one of ammonium perfluoropolyether carboxylate, sodium perfluoropolyether carboxylate, and potassium perfluoropolyether carboxylate. The emulsifier can be one of the above, such as sodium perfluoropolyether carboxylate. The emulsifier can reduce the surface tension between droplets and prevent aggregation of the monomer liquid or latex particles. At the same time, the emulsifier can be a mixture of two or more of the above. An initiator is a substance that can initiate the polymerization reaction of the monomer. For example, the initiator used in step 2 includes at least one of benzoyl peroxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate, di-normal-propyl peroxydicarbonate, diethyl peroxydicarbonate, and persulfates. The initiator can be one of the above. For example, the initiator is preferably diisopropyl peroxydicarbonate, or a mixture of two or more of the above.

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.

Polyvinylidene fluoride polymer is a polymer containing vinylidene fluoride as a monomer. The monomers of polyvinylidene fluoride polymer include, 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; there are no specific limitations.

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. In some embodiments, step 2 includes 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.

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

To effectively control the molecular weight of the reaction product, in step 2, water, a chain transfer agent, an emulsifier, an initiator, and the constituent monomers of the 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.

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.

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., without any specific limitations. Chain transfer agents include alcohol-based compounds, ester-based compounds, ketone-based compounds, and halogenated alkanes, and there are no limitations on the specific type of chain transfer agent.

In some embodiments, the combined 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 the water in steps 1 and 2 is deionized water.

Water acts as a dispersion medium, facilitating mass transfer and temperature control. If too little or too much water is used, it will be 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 should account for 45%-60% of the mass of all materials in steps 1 and 2, and may be, for example, 45%, 50%, 55%, 60%, etc., without any specific limitations. At the same time, the water in steps 1 and 2 should be deionized water to prevent impurities in the water from affecting the polymerization reaction.

The present application further provides a separator comprising the above-described adhesive or an adhesive obtained by the above-described adhesive manufacturing method. Since the adhesive employs all of the technical solutions of all of the above-described embodiments, it has at least all of the beneficial effects of the technical solutions of the above-described embodiments, and will not be further described here.

The separator is coated with the above adhesive, which improves the adhesive performance between the electrode plate and the adhesive and alleviates the problem of openings in the conventional battery core pre-cooling pressing process.

An embodiment of the present application further provides an electrode assembly, which includes the separator described above. Since the separator employs all of the technical solutions of all of the above embodiments, it has at least all of the beneficial effects of the technical solutions of the above embodiments, and will not be further described here.

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

An embodiment of the present application further provides a battery cell, which includes the electrode assembly described above. Since the electrode assembly employs all the technical solutions of all the above embodiments, it has at least all the beneficial effects of the technical solutions of the above embodiments, and will not be further described here.

By applying the above electrode assembly to a battery cell, the cycle performance of the battery cell's large jig can be improved.

An embodiment of the present application further provides a battery, which includes the above-described battery cell. The battery cell employs all the technical solutions of all the above-described embodiments, and therefore has at least all the beneficial effects of the technical solutions of the above-described embodiments, and will not be further described here.

The battery includes a battery module and a battery pack.

An embodiment of the present application further provides a power consumption device, which includes the above-mentioned battery cell or the above-mentioned battery. The battery cell or battery employs 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 will not be further described here.

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

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

Typically, an 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.

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.

For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is disposed on one or both of the two opposing surfaces of the positive electrode current collector.

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)).

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 for use 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. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO ₂ ), lithium nickel oxide (e.g., LiNiO ₂ ), lithium manganese oxide (e.g., LiMnO ₂ , LiMn ₂ O ₄ ), 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 O ₂ (which may be abbreviated as NCM ₃₃₃ ), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (which may be abbreviated as NCM ₅₂₃ ), LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (which may be abbreviated as NCM ₂₁₁ ), and LiNi _0.6 Co _0.2 Mn _0.2 O _{2 ). Examples} 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.

In some embodiments, the positive electrode film layer optionally further includes 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.

In some embodiments, the positive electrode film layer optionally further includes a conductive agent. By way of example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

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

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.

For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is disposed on one or both of the two opposing surfaces of the negative electrode current collector.

In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper 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 substrate. 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

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.

In some embodiments, the negative electrode film layer optionally further comprises an adhesive. The adhesive 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).

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

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

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

The electrolyte serves to conduct ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and it can be selected according to needs.

In some embodiments, the electrolyte is an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

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.

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.

In some embodiments, the electrolyte solution optionally further contains 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 certain battery performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

In some embodiments, the electrode assembly further includes a separator. This application does not specifically limit the type of separator, and any known porous separator with good chemical and mechanical stability may be selected.

In some embodiments, the separator material may be selected from 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, with no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, with no particular restrictions.

In some embodiments, the positive electrode plate, negative electrode plate, and separator can be fabricated into an electrode assembly by a winding process or a stacking process.

In some embodiments, the electrode assembly may include an outer casing. This outer casing may be used to package the electrode assembly and electrolyte.

In some embodiments, the exterior of the electrode assembly may be a hard case, such as a hard plastic case, an aluminum case, or a steel case. The exterior of the electrode assembly may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

This application does not specifically 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.

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, and the bottom plate and 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 within the accommodating cavity. The electrode assembly 52 is impregnated with an electrolyte. 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.

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, with the specific number being selectable by those skilled in the art depending on the application and capacity of the battery module.

Figure 7 shows an example battery module 4. Referring to Figure 7, in the battery module 4, multiple battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, these multiple battery cells 5 may be secured in place using fasteners.

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

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

Figures 8 and 9 show an example battery pack 1. Referring to Figures 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, forming an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

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.

As a power consumption device, an electrode assembly, a battery module, or a battery pack can be selected depending on its usage needs.

Figure 10 shows an example power consuming device. This power consuming device may be 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 this power consuming device, a battery pack or battery module may be employed.

Other example devices may be mobile phones, tablet computers, laptops, etc. These devices are generally required to be thin and use an electrode assembly as a power source.

Examples 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 the 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.

Example 1
Preparation of adhesive: Step 1: Add 752.4g of methyl acrylate, 185.5g of acrylonitrile, and 62.1g of acrylamide to a 5L high-pressure reactor, making the molar ratio between the three 1:0.4:0.1, and add 36g of sodium dodecyl sulfonate and 1.2kg of deionized water. Stir thoroughly to disperse and emulsify, heat to 70°C, add initiator solution (0.6g of potassium persulfate dissolved in deionized water), stir to react for 30 minutes, continue to heat to 80°C, use a peristaltic pump to slowly add initiator solution (1.2g of potassium persulfate dissolved in deionized water) dropwise, after adding, heat to 90°C and keep reacting for 0.5 hours, cool to 40°C, obtain core layer seed emulsion, and 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 gas. 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.

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 above was uniformly mixed with deionized water and stirred to obtain a slurry (20% solids). The slurry was uniformly applied to two surfaces of the substrate and dried to remove the solvent. The composition was then coated onto the substrate at a coating density of 1.0 g/ ^m² to obtain a separator.

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 homogenize, forming a positive electrode slurry. This positive electrode slurry was uniformly coated onto an aluminum foil positive electrode current collector at a loading of 200 g/ ^m2 , followed by drying, cold pressing, and slitting to obtain a positive electrode plate.

Negative electrode plate preparation: Artificial graphite, acetylene black (a conductive agent), styrene butadiene rubber (SBR) (an adhesive), and sodium carboxymethyl cellulose (CMC-Na) (a thickener) were added to deionized water in a mass ratio of 96.2:1.0:1.6:1.2 and thoroughly stirred to homogeneity, resulting in a negative electrode slurry (63% solids). This negative electrode slurry was coated onto a negative electrode current collector copper foil at a loading of 98 g/ ^m² , followed by drying, cold pressing, and slitting to obtain a negative electrode plate.

Preparation of Electrolyte Solution 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.

Manufacture of Battery Cell 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 process) to obtain an electrode assembly. The electrode assembly was then placed in an outer casing, the prepared electrolyte solution was added, and a battery cell was obtained after going through processes such as packaging, standing, chemical conversion, and aging.

The parameters (e.g., those shown in Table 1) were changed in Example 1 to obtain experimental data for Examples 2 to 11.

Comparative Example 1: Preparation of polyvinylidene fluoride polymer 200g of deionized water, 1g of sodium perfluoropolyether carboxylate, and 0.5g of diisopropyl peroxydicarbonate were added to a high-pressure reactor, and stirring was started. The reactor was evacuated and replaced with nitrogen gas. Vinylidene fluoride and hexafluoropropylene gas were introduced into the reactor, and the pressure inside the reactor was increased to 3.5MPa. The reaction temperature of the system was increased to 75°C to initiate the polymerization reaction. When the pressure inside the high-pressure reactor dropped to 3.0MPa, vinylidene fluoride and hexafluoropropylene gas were continued to be introduced to control the pressure inside the high-pressure reactor at 3.0-3.5MPa. A total of 200g of vinylidene fluoride and hexafluoropropylene were introduced. When the pressure dropped to 2MPa or less, the reaction was stopped, filtered, and discharged.

Comparative Example 2: Steps for preparing a polymer obtained by polymerizing a first flexible monomer: 752.4 g of methyl acrylate, 36 g of sodium dodecylsulfonate, and 1.2 kg of deionized water were added to a three-necked flask and thoroughly stirred to disperse and emulsify the mixture. The mixture was then heated 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 mixture was then heated 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 mixture was heated to 90°C and allowed to react for 0.5 hours while maintaining the temperature. 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.

Comparative Example 3: Preparation of a polymer obtained by polymerizing a second polymerizable polar monomer. Deionized water and a certain proportion of initiator were added to a three-neck flask equipped with a reflux condenser, thermometer, and stirring magnetron. 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 in small droplets 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, followed by filtration and discharge.

Comparative Example 4: Preparation of a polymer obtained by polymerizing a third polymerization molecular weight adjusting monomer. First, 120 g of water was added to 30 g to 90 g of acrylamide monomer to prepare an acrylamide solution. 0.02 g to 1 g of persulfate was dissolved in 30 g of water to obtain an initiator solution. 37.5 g of isopropyl alcohol solvent was added to a 250 mL four-neck reaction flask, the flask was opened and stirred. The stirring speed was set to 200 r/min, and the temperature was raised to reflux. The monomer solution and initiator solution were continuously added dropwise, controlling the dropping rate and the dropping time to 120 min. The reflux reaction was maintained for 2 hours, and the isopropyl alcohol was distilled off to obtain a polyacrylamide solution, which was then filtered and discharged.

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.

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

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.

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

The steel plate was held horizontally and fixed in place with the lower fixture of a universal testing machine (Xieqiang Machinery Manufacturing (Shanghai) Co., Ltd., model CTM2100). The peeled end of the separator was fixed with the upper fixture of the universal testing machine, and the 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.

2. Battery core hardness test step The battery core was placed on a horizontal table at both ends, and the width of the central openwork part was fixed at 12 cm. The battery core was placed naturally flat, and the deviation of the center position of the battery core from the horizontal reference line was measured to evaluate the battery core hardness. It was explained that the greater the deviation of the center position of the battery core from the horizontal reference line, the worse the battery core hardness.

3. Battery Cycle Performance Test Step 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 the difference in cycle performance.

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, using this adhesive in a battery separator can effectively improve the cycle performance of the battery.

The above is merely a preferred embodiment of the present application and does not limit the scope of the patent of the present application. Equivalent structural transformations made using the contents of the specification and drawings of the present application based on the application concept of the present application, or direct or indirect applications in other related technical fields, are all within the scope of patent protection of the present application.

Claims (15)

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) . The adhesive of claim 1, wherein the shell layer structure includes a plurality of cases, the cases being spaced apart on the surface of the core layer structure. 3. The adhesive according to claim 1, wherein the mass ratio of the polyacrylate polymer to the polyvinylidene fluoride polymer is (2-100):1. 3. The adhesive according to claim 1, wherein the adhesive has a volume average particle diameter Dv50 of 0.5 μm to 50 μm. 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). The adhesive according to claim 1 or 2, wherein the polyvinylidene fluoride polymer 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. A method for producing the adhesive according to claim 1 ,
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. 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. 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. 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. A separator comprising the adhesive of claim 1. An electrode assembly comprising the separator of claim 11 . A battery cell comprising the electrode assembly of claim 12 . A battery comprising the battery cell of claim 13 . A power consuming device comprising a battery cell according to claim 13 or a battery according to claim 14 .