Fluorine-containing polymers, manufacturing methods, insulating coatings, secondary batteries, power consumption devices

Abstract

The present application provides a fluorine-containing polymer, a production method, an insulating coating, a secondary battery, and an electric power consumption device. The fluorine-containing polymer contains a structural unit derived from a monomer represented by Formula I, a structural unit derived from an olefin monomer, and a structural unit derived from a monomer represented by Formula II. The molar content of the structural unit derived from the monomer represented by Formula I is 60% to 80% based on the total number of moles of the structural units in the fluorine-containing polymer. Here, R 1 , R 2 , R 3 are each independently selected from hydrogen, fluorine, chlorine, or a C 1-3 alkyl group containing at least one fluorine atom, and R 4 , R 5 , R 6 are each independently selected from hydrogen, or a substituted or unsubstituted C 1-5 alkyl group.

Description

[Technical Field]

[0001] This application relates to the technical field of secondary batteries, and more particularly to fluorine-containing polymers, manufacturing methods, insulating coatings, secondary batteries, and power consumption devices. [Background technology]

[0002] In the manufacturing process of battery cell electrode sheets, an insulating coating is applied to the surface of the current collector to prevent the positive and negative electrodes from coming into contact and forming a short circuit during use, which can lead to safety accidents, and ultimately to fires and explosions. While insulating coatings are often manufactured by coating the surface of the current collector with an insulating slurry containing adhesives, inorganic insulating materials, and additives, conventional insulating slurries have short process windows, poor fluidity, and are prone to pipe blockage due to sedimentation, significantly impacting the production efficiency of electrode sheets. Therefore, the development of adhesives to improve the processing performance of the slurry is urgently needed. [Overview of the project] [Problems that the invention aims to solve]

[0003] This application was made in view of the above-mentioned problems, and aims to provide a fluorine-containing polymer and an insulating coating containing the fluorine-containing polymer that optimize the process window for manufacturing insulating coatings and improve the production efficiency of insulating coatings. [Means for solving the problem]

[0004] A first aspect of the present application provides a fluorine-containing polymer comprising structural units derived from a monomer represented by formula I, structural units derived from an olefin monomer, and structural units derived from a monomer represented by formula II, wherein the molar content of the structural units derived from the monomer represented by formula I is 60% to 80% of the total number of moles of structural units in the fluorine-containing polymer. [ka] Here, R1, R2, and R3 are each independently hydrogen, fluorine, chlorine, or C containing at least one fluorine atom. 1-3 Selected from alkyl groups, R4, R5, and R6 are each independently hydrogen, substituted, or unsubstituted C 1-5 Selected from alkyl groups.

[0005] The fluorine-containing polymer according to this invention can improve the filterability and fluidity of the slurry, so that gelation does not occur even when the slurry is left to stand for 6 hours, the process window of the slurry is greatly expanded, the processability of the slurry is improved, and the slurry can meet the production needs of insulating coatings without the addition of a dispersant, which is advantageous for optimizing the production process of insulating coatings and improving production efficiency.

[0006] In any embodiment, R1 is fluorine, R2 and R3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and a trifluoromethyl group, and R5 and R6 are each independently selected from one or two of hydrogen and a methyl group.

[0007] In any embodiment, the molar content of structural units derived from the monomer represented by formula II is 5% to 25% of the total number of moles of all structural units in the fluorine-containing polymer.

[0008] When the molar content of structural units derived from the monomer shown in Formula II is 5% to 25% of the total number of moles of all structural units in the fluorine-containing polymer, the fluorine-containing polymer further improves the fluidity and filterability of the insulating slurry, broadens the process window for insulating slurry processing, and allows the insulating coating to also provide effective adhesion.

[0009] In any embodiment, the molar content of structural units derived from the olefin monomer is 5% to 30% of the total number of moles of all structural units in the fluorine-containing polymer.

[0010] When the molar content derived from the olefin monomer is 5% to 30% with respect to the total molar number of all structural units in the fluorine-containing polymer, the fluorine-containing polymer further improves the fluidity and filtration performance of the insulating slurry, the process window of the insulating slurry processing is further widened, and the insulating coating can have effective adhesion by the fluorine-containing polymer.

[0011] In any embodiment, the weight average molecular weight of the fluorine-containing polymer is 500,000 to 800,000.

[0012] A fluorine-containing polymer with a weight average molecular weight of 500,000 to 800,000 is advantageous for further improving the fluidity and filtration performance of the insulating slurry, widening the process window of the insulating slurry processing, and promoting maintaining effective adhesion of the insulating coating.

[0013] In any embodiment, the viscosity of the adhesive solution prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone is 1000 to 3000 mPa·s, and the mass content of the fluorine-containing polymer in the adhesive solution is 7% of the total mass of the adhesive solution.

[0014] Since the viscosity of the adhesive solution containing a fluorine-containing polymer with a mass content of 7% prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone is 1000 to 3000 mPa·s, it is not necessary to add additional additives to the insulating slurry using this fluorine-containing polymer as an adhesive, which can effectively optimize the production process, improve production efficiency, and at the same time, help improve the batch stability of the insulating coating.

[0015] In any embodiment, the monomer represented by the formula I is selected from one or more of vinylidene fluoride, tetrafluoroethylene, trifluorochloroethylene, and hexafluoropropylene.

[0016] In any embodiment, the olefin monomer is selected from one or more of propylene, 2-butene, and butadiene.

[0017] In any embodiment, the monomer represented by formula II is selected from one or two of acrylic acid and methacrylic acid.

[0018] A second aspect of the present application provides a method for producing a fluorine-containing polymer. The process includes the step of polymerizing at least one monomer represented by formula I, at least one olefin monomer, and at least one monomer represented by formula II under polymerizable conditions to produce a fluorine-containing polymer, wherein the molar content of the monomer represented by formula I is 60% to 80% of the total number of moles of the monomer represented by formula I, the olefin monomer, and the monomer represented by formula II. [ka] Here, R1, R2, and R3 are each independently hydrogen, fluorine, chlorine, or C containing at least one fluorine atom. 1-3 Selected from alkyl groups, R4, R5, and R6 are each independently hydrogen, substituted, or unsubstituted C 1-5 Selected from alkyl groups.

[0019] Compared to conventional adhesives, the fluorine-containing polymer produced by this method can improve the filterability and fluidity of the slurry. As a result, gelation does not occur even after the slurry is left to stand for 6 hours, the process window of the slurry is greatly expanded, the processability of the slurry is improved, and the slurry can meet the production needs of insulating coatings without the addition of dispersants. This is advantageous for optimizing the insulating coating production process and improving its production efficiency.

[0020] In any embodiment, R1 is fluorine, R2 and R3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and a trifluoromethyl group, and R5 and R6 are each independently selected from one or two of hydrogen and a methyl group.

[0021] In any embodiment, the polymerization reaction comprises a first-step polymerization and a second-step polymerization, In the first step polymerization, a first initiator, an emulsifier, at least one monomer represented by formula I and a solvent are provided, the first step polymerization is started, the monomer represented by formula I is continuously fed during the first step polymerization process, and the initial reaction pressure is maintained. In the second stage polymerization, after a certain period of time, olefin monomers and monomers represented by formula II are introduced into the reaction vessel to carry out the second stage polymerization. When the pressure inside the reaction vessel drops to 0.5 MPa or less, the reaction is stopped, the solid and liquid phases are separated, and the solid phase remains.

[0022] The method according to this invention first involves continuously feeding monomers represented by formula I to form fluorine-containing segments, thereby providing a fluorine-containing polymer with high thermal stability. Second, by introducing monomers represented by formula II and olefin-based monomers, contact between the fluorine-containing segments and the external environment is reduced, effectively mitigating the gelation phenomenon caused by fluorine. Compared to fluorine-containing polymers produced by introducing all monomers into the reaction vessel and polymerizing them, the fluorine-containing polymer produced by this method effectively improves the filterability and fluidity of the insulating slurry, further widening the slurry process window and contributing to improved production efficiency of insulating coatings.

[0023] In any embodiment, the initial reaction pressure of the first step polymerization is 5.5 MPa to 7.5 MPa, and the reaction temperature is 70°C to 90°C.

[0024] In any embodiment, the second step polymerization is When the mass of monomer represented by formula I introduced is 70%-85% of the total mass of monomer represented by formula I supplied to the polymerization reaction process, the reaction is continued by introducing a mixed gas of monomer represented by formula I and olefin monomer into the reaction vessel and maintaining the initial reaction pressure. The process includes the steps of first introducing all the monomers represented by formula I into the reaction vessel, and then introducing a mixture of olefin monomers and monomers represented by formula II into the reaction vessel.

[0025] Before introducing the monomer represented by formula II into the reaction vessel, a mixed gas of the monomer represented by formula I and an olefin monomer is first introduced into the reaction vessel. This helps overcome the problem of large reaction differences and low compatibility between the monomer represented by formula I and the monomer represented by formula II, by using the olefin monomer as a bridge, thereby improving the degree of polymerization of the fluorine-containing polymer.

[0026] In any embodiment, the ratio of the total number of moles of olefin monomers supplied in the polymerization reaction process to the total number of moles of the monomer represented by formula I is 1:16 to 1:2.

[0027] In any embodiment, the ratio of the total number of moles of olefin monomers supplied in the polymerization reaction process to the total number of moles of the monomer represented by formula I is 1:16 to 1:3.

[0028] In any embodiment, the molar ratio of the olefin monomer to the monomer represented by formula I in the mixed gas is 1:1 to 2:1.

[0029] In any embodiment, the molar ratio of the olefin monomer to the monomer represented by formula II in the mixture is 3:1 to 4:1.

[0030] In any embodiment, the second step polymerization is The process further includes adding a first initiator and a second initiator to the reaction vessel before introducing a mixed gas of the monomer represented by formula I and an olefin monomer into the reaction vessel.

[0031] In any embodiment, the second step polymerization is The process further includes adding a second initiator to the reaction vessel before introducing a mixture of the olefin monomer and the monomer represented by formula II into the reaction vessel.

[0032] In any embodiment, the first initiator is a persulfate, which can be selected from one or more of potassium persulfate and ammonium persulfate.

[0033] In any embodiment, the second initiator is a thiosulfate, which can be selected from sodium thiosulfate.

[0034] According to a third aspect of the present application, the use of a fluorine-containing polymer of the first aspect in a secondary battery is provided, wherein the secondary battery optionally includes at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery.

[0035] A fourth aspect of the present application provides an insulating coating comprising an adhesive and an inorganic insulating material, wherein the adhesive is a fluorine-containing polymer of the first aspect.

[0036] This insulating coating is easy to process and manufacture, has good uniformity, and helps improve battery productivity.

[0037] In any embodiment, the mass content of the adhesive is 7.0% to 13.0% of the total mass of the insulating coating.

[0038] When the mass content of the adhesive is 7.0% to 13.0% of the total mass of the insulating coating, the adhesive further improves the fluidity and filterability of the insulating slurry, widens the process window for insulating slurry processing, and ensures that the insulating coating maintains effective adhesion.

[0039] In any embodiment, the inorganic insulating material comprises a colored oxide, which can be selected from black zirconia, yellow zirconia, red zirconia, or green zirconia.

[0040] The applicant unexpectedly discovered that the inclusion of colored oxides in the insulating coating helps to improve the laser cutting quality and laser cutting speed of the electrode sheet.

[0041] In any embodiment, the mass content of the colored oxide is 0.2%-3% of the total mass of the insulating coating.

[0042] A mass content of colored oxides in the insulating coating of 0.2% to 3% helps to maximize laser cutting performance.

[0043] A fifth aspect of the present application provides a method for manufacturing an insulating coating. A step of preparing an adhesive solution by dispersing an adhesive which is a fluorine-containing polymer according to the first aspect of the present application in a solvent, The process involves mixing an inorganic insulating material with the adhesive solution and stirring to produce a slurry having a solid content of 30% to 40%, and The process includes the step of coating a current collector with the slurry to produce an insulating coating.

[0044] The insulating coating produced by the above method is highly efficient and has a uniform mass.

[0045] In any embodiment, if the solid content of the slurry is 30% to 40%, the viscosity of the slurry is 2500 to 4000 mPa·s.

[0046] A slurry with a solid content of 30% to 40% has a viscosity of 2500 to 4000 mPa·s and can be used directly in coating production without the need to increase additional additives, which is advantageous for improving production efficiency and reducing production costs.

[0047] In any embodiment, the step of mixing the inorganic insulating material with the adhesive solution is: The process includes the steps of mixing an inorganic insulating material other than the colored oxide with the adhesive solution, stirring, adding the colored oxide, and stirring again to produce the slurry.

[0048] Adding colored oxides in the final stage of the slurry manufacturing process improves the color uniformity of the manufactured insulating coating, which helps to improve subsequent laser cutting speed and quality.

[0049] A sixth aspect of the present application provides a secondary battery comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, wherein the positive electrode sheet and / or the negative electrode sheet includes an insulating coating according to the fourth aspect of the present application, and the secondary battery optionally comprises at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery.

[0050] A seventh aspect of the present application provides a battery module comprising a secondary battery according to a sixth aspect of the present application.

[0051] An eighth aspect of the present application provides a battery pack comprising a secondary battery according to the sixth aspect of the present application or a battery module according to the seventh aspect of the present application.

[0052] A ninth aspect of the present application provides a power consumption device comprising at least one selected from a secondary battery according to the sixth aspect of the present application, a battery module according to the seventh aspect of the present application, or a battery pack according to the eighth aspect of the present application. [Brief explanation of the drawing]

[0053] [Figure 1] This is a schematic diagram showing an electrode sheet with an insulating coating. [Figure 2] This is a schematic diagram showing a secondary battery according to one embodiment of the present invention. [Figure 3] Figure 2 is an exploded view showing a secondary battery according to one embodiment of the present invention. [Figure 4] This is a schematic diagram showing a battery module according to one embodiment of the present invention. [Figure 5] This is a schematic diagram showing a battery pack according to one embodiment of the present invention. [Figure 6] Figure 5 is an exploded view showing a battery pack according to one embodiment of the present invention. [Figure 7] This is a schematic diagram showing a power consumption device that uses a secondary battery as a power source according to one embodiment of the present invention. [Figure 8]These are microscopic images of the electrode sheet after laser cutting according to Example 26 of the present application, where (A) is a plan view of the cutout in the electrode sheet and (B) is a cross-sectional view of the cutout in the electrode sheet. [Figure 9] These are microscopic images of the electrode sheet after laser cutting according to Embodiment 6 of the present invention, where (A) is a plan view of the cutout in the electrode sheet and (B) is a cross-sectional view of the cutout in the electrode sheet. [Modes for carrying out the invention]

[0054] The following describes in detail embodiments of the adhesive, preparation method, electrode, battery, and power consumption device of the present application, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of the same actual structure may be omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding for 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.

[0055] The “range” disclosed in this application is limited in the form of a lower and upper limit, and a given range is limited by selecting one lower limit and one upper limit, and the boundaries of the special range are limited by the selected lower and upper limits. The range thus limited may include or exclude boundary values ​​and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Furthermore, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are listed, then all of the following ranges, 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5, can be expected. In this application, unless otherwise stated, the numerical range “a-b” is an abbreviated expression for any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0 to 5" refers to all real numbers between "0 to 5" listed herein, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter indicates an integer ≥ 2, that parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and preferably embodiments of the present application can be combined with each other to form new technical solutions.

[0057] Unless otherwise specified, all technical features of this application, and preferably all technical features, can be combined with each other to form new technical solutions.

[0058] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but it is preferable to perform them sequentially. For example, "The method includes steps (a) and (b)" means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, "The method described above may include step (c)" means that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b).

[0059] Unless otherwise specified, the terms “equipment” and “include” as used in this application may be non-restrictive or restrictive. For example, “equipment” and “include” may further equip or include other components not listed, or they may equip or include only the listed components.

[0060] Unless otherwise specified, the term “or” is inclusive in this application. For example, the phrase “A or B” means “A, B, or both A and B.” More specifically, any of the following conditions satisfy the “A or B” condition: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); or both A and B are true (or exist).

[0061] Safety is one of the most important research challenges for secondary batteries. As shown in Figure 1, the electrode sheet 6 has an insulating coating 63 applied between the current collector 61 and the active material layer 62 for forming tabs during the manufacturing process. This prevents the positive and negative electrodes from coming into contact and forming a short circuit during use, which can lead to safety accidents, and ultimately to fires and explosions. Inorganic materials have high resistance, and insulating coatings are often manufactured by dispersing inorganic materials in an adhesive to form a slurry. However, conventional adhesives have too high a viscosity, making slurry sedimentation more likely, resulting in poor slurry uniformity and large performance variations between batches of insulating coatings. Furthermore, conventional adhesives result in poor slurry fluidity and difficulty in uniform application, requiring the addition of a dispersant to improve slurry processing performance during the slurry manufacturing process. This increases the difficulty of slurry processing, affects production efficiency, and inevitably worsens slurry stability between batches. Based on the above technical problems, this invention aims to develop an adhesive that provides better fluidity and filterability to the slurry in order to improve the production efficiency and quality of insulating coatings.

[0062] Based on this, the present application provides a fluorine-containing polymer containing structural units derived from monomers represented by formula I, structural units derived from olefin monomers, and structural units derived from monomers represented by formula II, wherein the molar content of structural units derived from monomers represented by formula I is 60% to 80% of the total number of moles of structural units in the fluorine-containing polymer. [ka] Here, R1, R2, and R3 are each independently hydrogen, fluorine, chlorine, or C containing at least one fluorine atom. 1-3 Selected from alkyl groups, R4, R5, and R6 are each independently hydrogen, substituted, or unsubstituted C 1-5 Selected from alkyl groups.

[0063] In this specification, the term "fluorine-containing polymer" refers to a polymer in which the element fluorine is present in the structural units.

[0064] In this specification, the term "polymer" includes an aggregate of macromolecules that are chemically uniform but have different degrees of polymerization, molar masses, and chain lengths, and are produced by a polymerization reaction. On the other hand, the term also includes derivatives of such aggregates of macromolecules formed by a polymerization reaction, i.e., products that are chemically uniform or chemically non-uniform obtained by reactions of functional groups in the above macromolecules, such as addition or substitution.

[0065] In this specification, "C 1-5 alkyl group" means a straight-chain or branched hydrocarbon chain group consisting only of carbon and hydrogen atoms, having no unsaturation in the group, having 1 to 5 carbon atoms, and being bonded to the rest of the molecule by a single bond. "C 1-3 alkyl group" should be interpreted accordingly. Examples of C 1-5 alkyl groups include, but are not limited to, methyl group, ethyl group, n-propyl group, 1-methylethyl group (isopropyl group), butyl group, and pentyl group. In some embodiments, the C 1-3 alkyl group containing at least one fluorine atom is -CF3, -CH3CH2F, or -CH2FCH2F.

[0066] In this specification, the term "substituted" means that at least one hydrogen atom of the compound or chemical moiety is substituted with a substituent by another chemical moiety, where the substituents are each independently selected from a hydroxyl group, a mercapto group, an amino group, a cyano group, a nitro group, an aldehyde group, a halogen atom, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a C 1-6 alkyl group, and a C 1-6 alkoxy group.

[0067] In this specification, the term “olefinic monomer” refers to a hydrocarbon containing at least one C=C bond (carbon-carbon double bond). Examples of olefinic monomers include, but are not limited to, ethylene, propylene, butene, and butadiene. In some embodiments, R1 is fluorine, R2 and R3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and a trifluoromethyl group, and R5 and R6 are each independently selected from one or two of hydrogen and a methyl group.

[0068] In some embodiments, the fluorine-containing polymer comprises structural units derived from at least two different monomers represented by formula I, one of which is derived from vinylidene fluoride. The different monomer types help to reduce the regularity of the long chains of the fluorine-containing polymer, lower the degree of crystallinity, and improve flexibility.

[0069] In some embodiments, the monomer represented by formula I is selected from one or more of vinylidene fluoride, tetrafluoroethylene, trifluorochloroethylene, and hexafluoropropylene.

[0070] In some embodiments, the olefin monomer is selected from one or more of propylene, 2-butene, and butadiene.

[0071] In some embodiments, the monomer represented by formula II is selected from one or two of acrylic acid and methacrylic acid.

[0072] In some embodiments, the polymer contains structural units derived from one or more monomers represented by formula I. In some embodiments, the polymer contains structural units derived from one or more monomers represented by formula II. In some embodiments, the polymer includes, but is not limited to, vinylidene fluoride-ethylene-acrylic acid copolymer, vinylidene fluoride-butadiene-acrylic acid copolymer, vinylidene fluoride-propylene-acrylic acid copolymer, vinylidene fluoride-ethylene-methacrylic acid copolymer, vinylidene fluoride-hexafluoropropylene-ethylene-acrylic acid copolymer, vinylidene fluoride-hexafluoropropylene-ethylene-methacrylic acid copolymer, and vinylidene fluoride-trifluorochloroethylene-butadiene-methacrylic acid copolymer.

[0073] In some embodiments, the molar content of structural units derived from the monomer represented by formula I may be 60%, 65%, 70%, 75%, or 80% of the total number of moles of structural units in the fluorine-containing polymer.

[0074] The fluorine elements in the structural units derived from the monomer shown in Formula I form hydrogen bonds with the hydroxyl groups and / or carboxyl groups on the current collector surface, resulting in excellent adhesion of the insulating coating, making it less likely to detach during manufacturing and use, thus reducing the risk of safety accidents. Structural units derived from olefin monomers and the monomer shown in Formula II can effectively reduce the fluorine content of the fluorine-containing polymer, resulting in a molar content of 60%-80% of structural units derived from the monomer shown in Formula I, which can improve the gelation phenomenon of the slurry due to fluorine. Furthermore, structural units derived from olefin monomers and the monomer shown in Formula II further increase the steric hindrance of the fluorine-containing polymer, reducing aggregation of fluorine-containing units, stabilizing the slurry, mitigating slurry sedimentation, and effectively improving the slurry's filterability.

[0075] The fluorine-containing polymer according to this invention can improve the filterability and fluidity of the slurry compared to conventional adhesives. As a result, gelation does not occur even when the slurry is left to stand for 6 hours, the process window of the slurry is greatly expanded, the processability of the slurry is improved, and the slurry can meet the production needs of insulating coatings without the addition of a dispersant. This is advantageous for optimizing the production process of insulating coatings and improving their production efficiency.

[0076] In this specification, the term "process window" refers to a process interval for product quality, which includes, but is not limited to, temperature intervals, pressure intervals, and storage time length. It can be understood that the wider the process window, the lower the demand for process precision.

[0077] In some embodiments, the molar content of structural units derived from the monomer represented by formula II is 5% to 25% of the total number of moles of all structural units in the fluorine-containing polymer. In some embodiments, the molar content of structural units derived from the monomer represented by formula II may be any of 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, or 25% of the total number of moles of all structural units in the fluorine-containing polymer.

[0078] When the molar content of structural units derived from the monomer shown in Formula II is 5% to 25% of the total number of moles of all structural units in the fluorine-containing polymer, an appropriate amount of polar carboxyl groups further improves the fluidity and filterability of the insulating slurry without causing gelation of the slurry, thereby broadening the process window for insulating slurry processing, while the appropriate amount of carboxyl groups allows the insulating coating to maintain effective adhesion.

[0079] In some embodiments, the molar content of structural units derived from olefin monomers is 5% to 30% of the total number of moles of all structural units in the fluorine-containing polymer. In some embodiments, the molar content of structural units derived from olefin monomers may be any of 5%, 10%, 15%, 20%, 25%, or 30% of the total number of moles of all structural units in the fluorine-containing polymer.

[0080] When the molar content derived from olefin monomers is 5% to 30% of the total number of moles of all structural units in the fluorine-containing polymer, the fluorine-containing polymer further improves the fluidity and filterability of the insulating slurry, broadens the process window for insulating slurry processing, and allows the insulating coating to maintain effective adhesion.

[0081] In some embodiments, the weight-average molecular weight of the fluorine-containing polymer is 500,000 to 800,000. In some embodiments, the weight-average molecular weight of the fluorine-containing polymer may be any of 500,000, 600,000, 650,000, 700,000, 750,000, or 800,000.

[0082] In this specification, the term "weight-average molecular weight" means the sum of the products of the weight fractions of molecules with different molecular weights that make up the polymer, and the corresponding molecular weights.

[0083] In this application, the weight-average molecular weight of the polymer can be measured using methods known in the art, such as gel chromatography or a Waters 2695 Isocratic HPLC-type gel chromatograph (differential refractive detector 2141). In some embodiments, the measurement method is as follows: a 3.0% polystyrene solution sample is used as a reference, and a suitable column (oil-based: Styragel HT5DMF 7.8*300mm + Styragel HT4) is selected. A 3.0% fluorine-containing polymer adhesive solution is prepared in purified N-methylpyrrolidone (NMP) solvent, and the prepared solution is allowed to stand for one day to prepare it for use. At the time of measurement, first, tetrahydrofuran is drawn into the syringe, washed, and repeated several times. Next, 5 ml of the experimental solution is drawn, air is removed from the syringe, and the needle tip is wiped. Finally, the sample solution is slowly injected into the inlet. After the reading stabilizes, the data is acquired and the weight-average molecular weight is read.

[0084] Fluorine-containing polymers with a weight-average molecular weight of 500,000 to 800,000 have an appropriate viscosity for the adhesive solution, further improving the fluidity and filterability of the insulating slurry, which is advantageous in broadening the process window for insulating slurry processing. At the same time, fluorine-containing polymers with an appropriate weight-average molecular weight are advantageous in forming a three-dimensional mesh-like adhesive structure, which helps the insulating coating maintain effective adhesive strength.

[0085] In some embodiments, the viscosity of the adhesive solution prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone is 1000 to 3000 mPa·s, and the mass content of the fluorine-containing polymer in the adhesive solution is 7% of the total mass of the adhesive solution. In some embodiments, the viscosity of the adhesive solution prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone may be any of 1000 mPa·s, 1500 mPa·s, 2000 mPa·s, 2500 mPa·s, or 3000 mPa·s, and the mass content of the fluorine-containing polymer in the adhesive solution is 7% of the total mass of the adhesive solution.

[0086] In this application, the viscosity of the adhesive solution of the fluorine-containing polymer can be measured using methods known in the art, such as a rotational viscosifier.

[0087] The viscosity of the adhesive solution prepared by dissolving a fluorine-containing polymer in N-methylpyrrolidone is 1000-3000 mPa·s, and the mass content of the fluorine-containing polymer in the adhesive solution is 7% of the total mass of the adhesive solution. This eliminates the need to add additional additives to the insulating slurry used as an adhesive, effectively optimizing the production process and improving production efficiency. At the same time, the adhesive solution within this viscosity range possesses both fluidity and viscosity, improving the adhesion of the insulating coating, achieving a uniform coating, and contributing to improved batch stability of the insulating coating.

[0088] In one embodiment of this application, a method for producing a fluorine-containing polymer is provided, The process includes the step of polymerizing at least one monomer represented by formula I, at least one olefin monomer, and at least one monomer represented by formula II under polymerizable conditions to produce a fluorine-containing polymer, wherein the molar content of the monomer represented by formula I is 60% to 80% of the total number of moles of the monomer represented by formula I, the olefin monomer, and the monomer represented by formula II. [ka] Here, R1, R2, and R3 are each independently hydrogen, fluorine, chlorine, or C containing at least one fluorine atom. 1-3 Selected from alkyl groups, R4, R5, and R6 are each independently hydrogen, substituted, or unsubstituted C 1-5 Selected from alkyl groups.

[0089] In this specification, the term “polymerizable conditions” refers to conditions including temperature, pressure, reactant concentration, any solvent / diluent, reactant mixing / addition parameters, and other conditions that facilitate the reaction of one or more monomers in at least one polymerization reactor, as selected by those skilled in the art.

[0090] Compared to conventional adhesives, the fluorine-containing polymer produced by this method can improve the filterability and fluidity of the slurry. As a result, gelation does not occur even after the slurry is left to stand for 6 hours, the process window of the slurry is greatly expanded, the processability of the slurry is improved, and the slurry can meet the production needs of insulating coatings without the addition of dispersants. This is advantageous for optimizing the insulating coating production process and improving its production efficiency.

[0091] In some embodiments, R1 is fluorine, R2 and R3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and a trifluoromethyl group, and R5 and R6 are each independently selected from one or two of hydrogen and a methyl group.

[0092] In some embodiments, at least two monomers represented by formula I are added during the polymer manufacturing process, where one monomer represented by formula I is polyvinylidene fluoride. The addition of different monomers helps to reduce the regularity of the long chains of the fluorine-containing polymer, lower the degree of crystallinity, and improve flexibility.

[0093] In some embodiments, the polymerization reaction includes a first-step polymerization and a second-step polymerization. In the first step polymerization, a first initiator, an emulsifier, at least one monomer represented by formula I and a solvent are provided, the first step polymerization is started, the monomer represented by formula I is continuously fed during the first step polymerization process, and the initial reaction pressure is maintained. In the second stage polymerization, after a certain period of time, olefin monomers and monomers represented by formula II are introduced into the reaction vessel to carry out the second stage polymerization. When the pressure inside the reaction vessel drops to 0.5 MPa or less, the reaction is stopped, the solid and liquid phases are separated, and the solid phase remains.

[0094] In this specification, the term "continuously supplying" means adding monomers slowly, in small amounts, and in stages.

[0095] In some embodiments, the first initiator is a persulfate, which can be selected from one or more of potassium persulfate and ammonium persulfate. Potassium persulfate decomposes efficiently at temperatures above 60°C, generating radical ions or ionic radicals, and is suitable as an initiator for emulsion polymerization.

[0096] In some embodiments, the emulsifier is an alkali metal perfluorooctanoate salt, and may also be a sodium perfluorooctanoate salt.

[0097] In some embodiments, the solvent is aqueous, which may be deionized water.

[0098] The method according to this invention first involves continuously feeding monomers represented by formula I to form a fluorine-containing segment, thereby providing a fluorine-containing polymer with high thermal stability. Second, by introducing monomers represented by formula II and olefin-based monomers, contact between the fluorine-containing segment and the external environment is reduced, effectively mitigating the gelation phenomenon caused by fluorine. Compared to fluorine-containing polymers produced by introducing all monomers into the reaction vessel and polymerizing them, the fluorine-containing polymer produced by this method can more effectively improve the filterability and fluidity of the slurry, further widening the slurry process window and contributing to improved production efficiency of insulating coatings.

[0099] In some embodiments, the initial reaction pressure of the first step polymerization is 5.5 MPa to 7.5 MPa, and the reaction temperature is 70°C to 90°C.

[0100] In some embodiments, the second step polymerization is If the mass of the monomer represented by formula I that is introduced is 70% to 85% of the total mass of the monomer represented by formula I supplied in the polymerization reaction process, the reaction is continued by introducing a mixed gas of the monomer represented by formula I and the olefin monomer into the reaction vessel and maintaining the initial reaction pressure. The process includes the steps of first introducing all of the monomers represented by formula I into the reaction vessel, and then introducing a mixture of the olefin monomer and the monomer represented by formula II into the reaction vessel.

[0101] Before introducing the monomer represented by formula II into the reaction vessel, a mixed gas of the monomer represented by formula I and an olefin monomer is first introduced into the reaction vessel. This helps overcome the problem of large reaction differences and low compatibility between the monomer represented by formula I and the monomer represented by formula II, by using the olefin monomer as a bridge, thereby improving the degree of polymerization of the fluorine-containing polymer.

[0102] In some embodiments, the ratio of the total number of moles of olefin monomers supplied to the polymerization reaction process to the total number of moles of monomers represented by formula I is 1:16 to 1:2.

[0103] In some embodiments, the ratio of the total number of moles of monomer represented by formula II to the total number of moles of monomer represented by formula I supplied to the polymerization reaction process is 1:16 to 1:3.

[0104] In some embodiments, the molar ratio of the olefin monomer to the monomer represented by formula I in the mixed gas is 1:1 to 2:1.

[0105] In some embodiments, the molar ratio of the olefin monomer to the monomer represented by formula II in the mixture is 3:1 to 4:1.

[0106] In some embodiments, the second step polymerization is The process further includes adding a first initiator and a second initiator to the reaction vessel before introducing a mixed gas of the monomer represented by formula I and an olefin monomer into the reaction vessel.

[0107] In some embodiments, the second initiator is a thiosulfate, which can be selected from sodium thiosulfate. As a reducing agent, the thiosulfate reacts with the first initiator, a persulfate, in the reaction vessel to produce two free radicals, effectively inducing polymerization of the olefin monomer.

[0108] In some embodiments, the second step polymerization is The process further includes adding a second initiator to the reaction vessel before introducing a mixture of the olefin monomer and the monomer represented by formula II into the reaction vessel.

[0109] In one embodiment of the present application, the use of a fluorine-containing polymer in a secondary battery by any embodiment is provided, wherein the secondary battery optionally includes at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery. In some embodiments, the fluorine-containing polymer is used in the secondary battery as an adhesive. In some embodiments, the fluorine-containing polymer is used in the secondary battery as an adhesive for an insulating coating.

[0110] [Insulating coating] In one embodiment of the present invention, an insulating coating comprising an adhesive and an inorganic insulating material is provided, wherein the adhesive is a fluorine-containing polymer in any embodiment.

[0111] In this specification, the term “adhesive” refers to a chemical compound, polymer, or mixture that forms a colloidal solution or colloidal dispersion in a dispersion medium.

[0112] In this application, the term "inorganic insulating material" refers to a material with a resistivity coefficient of 10 6 This term refers to inorganic materials and their precursors with a density exceeding Ω·cm, and includes, but is not limited to, boehmite, barium carbonate, barium sulfate, alumina, zirconia, calcium carbonate, and silica.

[0113] In some embodiments, the inorganic insulating material includes boehmite. Boehmite (AlOOH) is a precursor of γ-Al2O3, possesses excellent adhesion to current collectors, and is resistant to detachment as an insulating coating. In some embodiments, the inorganic insulating material includes zirconia. Zirconia has high resistance and is suitable for the manufacture of insulating coatings.

[0114] In some embodiments, the dispersion medium for the adhesive is an aqueous solvent such as deionized water. That is, the adhesive dissolves in the aqueous solvent.

[0115] In some embodiments, the dispersion medium for the adhesive is an oily solvent, which includes, but is not limited to, dimethylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, dimethyl carbonate, ethylcellulose, and polycarbonate. That is, the adhesive dissolves in the oily solvent.

[0116] In some embodiments, the adhesive is used to fix inorganic insulating materials in the appropriate position and to bond them to a current collector to form an insulating coating.

[0117] This insulating coating is easy to process and manufacture, has good uniformity, and helps improve battery productivity.

[0118] In some embodiments, the mass content of the adhesive is 7.0% to 13.0% of the total mass of the insulating coating. In some embodiments, the mass content of the adhesive may be any of 7.0%, 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, or 13.0% of the total mass of the insulating coating.

[0119] When the mass content of the adhesive is 7.0% to 13.0% of the total mass of the insulating coating, the insulating slurry has an appropriate viscosity, further improving the fluidity and filterability of the insulating slurry, and further widening the process window for insulating slurry processing. At the same time, an appropriate range of adhesive mass content ensures that the insulating coating has sufficient adhesion to the current collector.

[0120] In some embodiments, the inorganic insulating material includes a colored oxide, which can be selected from one or more of black zirconia, yellow zirconia, red zirconia, and green zirconia, and in some embodiments, the colored oxide is colored zirconia. In some embodiments, the inorganic insulating material includes black zirconia.

[0121] The applicant unexpectedly discovered that including colored oxides in the insulating coating helps improve the laser cutting quality and speed of electrode sheets. Laser cutting is a technique for processing materials by irradiating a workpiece with a focused, high-power-density laser beam, rapidly heating the irradiated material to melt, vaporize, ablate, or decompose it. The use of laser cutting technology in secondary batteries mainly includes laser electrode sheet cutting, tab cutting, and separator cutting. Currently, laser-cut electrode sheets have problems such as a lot of burrs in the cut area and limited maximum cutting speed. In conventional technology, inorganic insulating materials are generally colorless or white powders. The applicant found that including colored oxides in the inorganic insulating material improves the maximum cutting speed of electrode sheets by more than 30%, which helps to significantly increase the productivity of batteries. At the same time, the colored oxides in the inorganic insulating material can reduce the heat-affected zone of the laser, improve cutting quality, reduce cutting burrs, and reduce the impact of the processing process on battery performance.

[0122] In some embodiments, the mass content of the colored oxide is 0.2% to 3% of the total mass of the insulating coating.

[0123] When the mass content of colored oxides in the insulating coating is 0.2% to 3%, it not only improves the cutting speed during the laser cutting and forming process of the electrode sheet, but also helps to reduce raw material costs and maximize the improvement of laser cutting performance.

[0124] In some embodiments, the colored oxide is black zirconia. When the mass content of the colored oxide in the insulating coating exceeds 3.0%, there is no color difference between the insulating coating and the active material layer, making it difficult for the laser cutting system to recognize and position it, which is detrimental to accurate size cutting.

[0125] In one embodiment of the present application, a method for manufacturing an insulating coating is provided, A step of preparing an adhesive solution by dispersing an adhesive, which is a fluorine-containing polymer in any embodiment, in a solvent, The process involves mixing an inorganic insulating material and an adhesive solution, stirring them to produce a slurry with a solid content of 30% to 40%, and The process includes the step of coating a current collector with a slurry to produce an insulating coating.

[0126] Since the solid content of the slurry is 30% to 40%, the slurry has an appropriate viscosity, which is advantageous for subsequent coating and drying operations. At the same time, the appropriate slurry viscosity can improve the stability of the slurry, which is advantageous for slurry storage.

[0127] The above method offers high manufacturing efficiency for insulating coatings, eliminates the need for other additives, and is advantageous for saving production steps and improving production efficiency.

[0128] In some embodiments, when the solid content of the slurry is 30% to 40%, the viscosity of the slurry is 2500 to 4000 mPa·s. In some embodiments, when the solid content of the slurry is 30% to 40%, the viscosity may be any of 2750 mPa·s, 3000 mPa·s, 3250 mPa·s, 3500 mPa·s, 3750 mPa·s, or 4000 mPa·s.

[0129] A slurry with a solid content of 30% to 40% has a viscosity of 2500 to 4000 mPa·s and can be used directly in coating production without the need to increase additional additives, which is advantageous for improving production efficiency and reducing production costs.

[0130] In some embodiments, the step of mixing an inorganic insulating material with an adhesive solution is, The process includes the steps of mixing an inorganic insulating material other than the colored oxide with the adhesive solution, stirring, adding the colored oxide, and stirring again to produce the slurry.

[0131] Adding colored oxides in the final stage of the slurry manufacturing process improves the color uniformity of the manufactured insulating coating, which helps to improve subsequent laser cutting speed and quality.

[0132] One embodiment of the present application provides a secondary battery comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, wherein the positive electrode sheet and / or the negative electrode sheet include an insulating coating as described in any embodiment. In some embodiments, the secondary battery includes at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery. During the battery charging and discharging process, active ions are intercepted and deintercepted between the positive electrode sheet and the negative electrode sheet. The electrolyte is located between the positive electrode sheet and the negative electrode sheet and serves to conduct ions. The separator is provided between the positive electrode sheet and the negative electrode sheet and primarily serves to prevent short circuits between the positive and negative electrodes, while simultaneously allowing ions to pass through.

[0133] [Positive electrode sheet] The positive electrode sheet comprises a positive electrode current collector, a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and an insulating coating.

[0134] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode active material layer and insulating coating are provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0135] In some embodiments, the positive electrode current collector can be a metal foil sheet or a composite current collector. For example, aluminum foil can be used as the metal foil sheet. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0136] In some embodiments, the positive electrode active material can be a positive electrode active material for batteries that is well known in the art. For example, the positive electrode active material may include at least one of olivine-structured lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. The present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (It can also be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (It can also be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (It can also be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2O2(NCM 622 (It can also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (It can also be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 The olivine structure lithium-containing phosphate includes, but is not limited to, at least one of O2 and its modified compounds. Examples of olivine structure lithium-containing phosphates include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites.

[0137] In some embodiments, the positive electrode active material layer optionally further comprises an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins.

[0138] In some embodiments, the positive electrode active material layer optionally further comprises a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0139] In some embodiments, a positive electrode sheet can be manufactured as follows: components for manufacturing the positive electrode active material layer, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated onto a positive electrode current collector; and after processes such as drying and cold pressing, a positive electrode active material layer is obtained. Alternatively, components for manufacturing the insulating coating, such as a fluorine-containing polymer, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form an adhesive solution; an inorganic insulating material and the adhesive solution are mixed and stirred to produce an insulating slurry; the insulating slurry is coated onto the positive electrode current collector along the edge of the positive electrode active material layer; and after processes such as drying and cold pressing, an insulating coating is obtained; and a positive electrode sheet can be obtained by similarly acquiring the positive electrode active material layer and insulating coating on the other side of the current collector.

[0140] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector, a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and an insulating coating.

[0141] For example, a negative electrode current collector has two opposing surfaces in the thickness direction of itself, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0142] In some embodiments, the negative electrode current collector can be a metal foil sheet or a composite current collector. For example, copper foil can be used as the metal foil sheet. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0143] In some embodiments, the negative electrode active material can be a positive electrode active material for batteries that is well known in the art. For example, the negative electrode active material may include at least one of materials such as artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, stinate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0144] In some embodiments, the negative electrode active material layer optionally further comprises an adhesive. The adhesive can 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).

[0145] In some embodiments, the negative electrode active material layer optionally further comprises a conductive agent. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0146] In some embodiments, the negative electrode active material layer may further contain other auxiliary agents, such as a thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0147] In some embodiments, a negative electrode sheet can be manufactured as follows: components for manufacturing the negative electrode active material layer, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector; and after processes such as drying and cold pressing, a negative electrode active material layer is obtained. Alternatively, components for manufacturing the insulating coating, such as a fluorine-containing polymer, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form an adhesive solution; an inorganic insulating material and the adhesive solution are mixed and stirred to produce an insulating slurry; the insulating slurry is coated onto the negative electrode current collector along the edge of the negative electrode active material layer; and after processes such as drying and cold pressing, an insulating coating is obtained; and a negative electrode sheet can be obtained by similarly acquiring the negative electrode active material layer and insulating coating on the other side of the negative electrode current collector.

[0148] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. This application is not specifically limited to the type of electrolyte and can be selected as needed. For example, the electrolyte can be a liquid, a gel, or an all-solid.

[0149] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution contains an electrolyte salt and a solvent.

[0150] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoride arsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate)borate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0151] In some embodiments, the solvent can 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, methyl ethyl sulfone, and diethyl sulfone.

[0152] In some embodiments, the electrolyte may further optionally include additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and additives that can improve certain performance characteristics of the battery, such as additives that improve the overcharge performance of the battery and additives that improve the high-temperature or low-temperature performance of the battery.

[0153] [Separator] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous structure separator having excellent chemical and mechanical stability can be selected.

[0154] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator is not particularly limited and may be a single-layer thin film or a multilayer composite thin film. If the separator is a multilayer composite thin film, the materials of each layer are not particularly limited and may be the same or different.

[0155] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured as an electrode assembly by a winding process or a lamination process.

[0156] In some embodiments, the secondary battery may include an enclosure. The enclosure can be used to seal the electrode assembly and electrolyte.

[0157] In some embodiments, the casing of the secondary battery may be a hard shell, such as a rigid plastic shell, an aluminum shell, or a steel shell. The casing of the secondary battery may also be a soft bag, such as a pouch soft bag. The material of the soft bag may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0158] The present invention does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Figure 2 is an example of a rectangular secondary battery 5.

[0159] In some embodiments, referring to Figure 3, the exterior may include a housing 51 and a cover plate 53. Here, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates may enclose a storage chamber. The housing 51 has an opening that communicates with the storage chamber, and the cover plate 53 may cover the opening to close the storage chamber. The positive electrode sheet, negative electrode sheet, and separator may form an electrode assembly 52 by a winding or laminating process. The electrode assembly 52 is sealed inside the storage chamber. The electrolyte permeates into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to specific practical requirements.

[0160] In some embodiments, the secondary battery can be assembled as a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0161] Figure 4 shows an example of a battery module 4. Referring to Figure 4, in the battery module 4, multiple secondary batteries 5 are arranged sequentially along the length of the battery module 4. Of course, they may be distributed in any other manner. Furthermore, the multiple secondary batteries 5 can be secured with fasteners.

[0162] Optionally, the battery module 4 may further include an external case having storage space, in which multiple secondary batteries 5 are housed.

[0163] In some embodiments, the battery modules may be further assembled as a battery pack, and the number of battery modules included in the battery pack may be one or more, and a person skilled in the art can select the specific number depending on the use and capacity of the battery modules.

[0164] Figures 5 and 6 show an example of a battery pack 1. Referring to Figures 5 and 6, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided inside the battery box. The battery box includes an upper box 2 and a lower box 3, and the upper box 2 can be covered by the lower box 3, forming a closed space for housing the battery modules 4. The plurality of battery modules 4 can be distributed inside the battery box in any manner.

[0165] The present invention further provides a power consumption device comprising at least one of the secondary battery, battery module, or battery pack provided herein. The secondary battery, battery module, or battery pack can be used as a power source for the power consumption device and can also be used as an energy storage unit for the power consumption device. The power consumption device includes, 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.), trains, ships and satellites, and energy storage systems.

[0166] As the power consumption device, a secondary battery, battery module, or battery pack can be selected according to the requirements of use.

[0167] Figure 7 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery of this power consumption device, a battery pack or battery module can be used.

[0168] Other examples of the device may include mobile phones, tablets, and laptop computers. Such devices are typically required to be thin and can use rechargeable batteries as a power source.

[0169] Examples

[0170] Examples of the present application are described below. The examples described below are illustrative and are used solely for interpreting the present application and should not be understood as limiting the present application. Where no specific technique or conditions are shown in the examples, the application should be carried out in accordance with the technique or conditions described in the literature of the art or in accordance with the product specification. Where the manufacturer of the reagents or equipment used is not indicated, they are conventional products available on the market.

[0171] 1. Manufacturing method

[0172] Example 1 1) Manufacturing of adhesives (fluorine-containing polymers) 30 kg of deionized water (conductivity less than 2 μs / cm), 21 g of sodium perfluorooctanoate, and 71.4 g of 5% potassium persulfate solution were sequentially added to the reaction vessel, and the reaction vessel was closed. The inside of the vessel is evacuated, nitrogen gas is filled in, and this process is repeated until the oxygen concentration inside the reaction vessel falls below 100 ppm. The vinylidene fluoride monomer is introduced into the reaction vessel until the internal pressure reaches 7.5 MPa. The reaction is initiated by raising the temperature inside the vessel to 85°C, and vinylidene fluoride monomers are continuously introduced during the reaction process to maintain a constant reaction pressure inside the vessel. Vinylidene fluoride monomers were introduced until they reached 80% of the total mass of vinylidene fluoride monomers. Then, 30.6 g of 5% potassium persulfate solution and 19.2 g of 5% sodium thiosulfate were added, and while maintaining the reaction pressure, a mixed gas of vinylidene fluoride monomers and butadiene was introduced into the reaction vessel. The molar ratio of vinylidene fluoride monomers to butadiene monomers was 2:3. Add all 3783.7g of vinylidene fluoride monomer, and if the amount of butadiene monomer added accounts for 50% of the total amount of butadiene, add the remaining 28.8g of 5% sodium thiosulfate, maintain the reaction pressure, and introduce the remaining 931g of butadiene monomer and 354.7g of acrylic acid monomer into the reaction vessel. When the reaction is complete, the pressure inside the vessel is reduced to 0.2 MPa, the unreacted butadiene monomer is recovered and reacted, and the product is aggregated, washed, separated, dried, and pulverized to obtain a vinylidene fluoride-butadiene-acrylic acid copolymer adhesive.

[0173] 2) Manufacturing of insulating slurry 13,000 g of N-methylpyrrolidone was added to a 35 L stirring tank. The 700g of the vinylidene fluoride-butadiene-acrylic acid copolymer powder produced above was added to N-methylpyrrolidone, the stirring speed was set to 1000 revolutions / minute, and the stirring time was 60 minutes. After the stirring was completed, a temporary adhesive solution was obtained. 6195g of boehmite powder was added to the temporary adhesive solution, the stirring speed was set to 1200 revolutions / minute, and the stirring time was 60 minutes. The stirring tank started circulating cooling water, and after stirring was completed, a boehmite slurry was obtained. 105 g of black zirconia powder is added to the boehmite slurry, the stirring speed is set to 1200 revolutions / minute, the stirring time is 60 minutes, the stirring tank starts circulating cooling water, vacuuming is started, and stirring is completed to obtain an insulating slurry.

[0174] 3) Manufacturing of insulating coatings The above insulating slurry was coated onto a 13 μm aluminum foil, resulting in a coating thickness of 15 ± 1 μm. The slurry was dried to form an insulating coating, and an insulating coating was obtained on the other side of the aluminum foil using the same method. The sum of the thickness of the insulating coatings on both sides and the thickness of the aluminum foil is 43 ± 2 μm.

[0175] The manufacturing methods for the insulating coatings in Examples 2-26 and Comparative Examples 1-4 are similar to those in Example 1, but the manufacturing parameters of the adhesive and the proportion of black zirconia in the slurry were adjusted.

[0176] In Examples 2 to 7, the proportions of each monomer in the adhesive were adjusted, while other parameters were the same as in Example 1. The specific parameters are shown in Tables 1 and 2.

[0177] In Examples 8 to 11, different weight-average molecular weights were obtained for the adhesives by adjusting the reaction conditions in the synthesis of the adhesives, while other parameters were the same as in Example 6. The specific parameters are shown in Tables 1 and 2. Specifically, the method for producing a fluorine-containing polymer with a weight-average molecular weight of 500,000 in Example 8 is almost the same as the steps in Example 6, the only difference being that the amount of 5% potassium persulfate solution added was adjusted from 71.4 g to 78.54 g.

[0178] The method for producing a fluorine-containing polymer with a weight-average molecular weight of 800,000 in Example 9 is almost the same as the steps in Example 6, the only difference being that the reaction temperature is adjusted from 85°C to 80°C and the amount of 5% potassium persulfate solution added is adjusted from 71.4 g to 67.83 g.

[0179] The method for producing a fluorine-containing polymer with a weight-average molecular weight of 900,000 in Example 10 is almost the same as the steps in Example 6, the only difference being that the reaction temperature is adjusted from 85°C to 80°C and the amount of 5% potassium persulfate solution added is adjusted from 71.4 g to 64.26 g.

[0180] The method for producing a fluorine-containing polymer with a weight-average molecular weight of 400,000 in Example 11 is almost the same as the steps in Example 6, the only difference being that the amount of 5% potassium persulfate solution added is adjusted from 71.4 g to 82.11 g.

[0181] The mass fraction of the adhesive in the slurry in Examples 12 to 15 was adjusted, while other parameters were the same as in Example 6. The specific parameters are shown in Tables 1 and 2.

[0182] In Examples 16-19, the solid content of the slurry was adjusted, while other parameters were the same as in Example 6. The specific parameters are shown in Tables 1 and 2.

[0183] In Example 20, butadiene in the adhesive synthesis monomer was replaced with propylene, and the other parameters were the same as in Example 6. The specific parameters are shown in Tables 1 and 2.

[0184] In Example 21, the adhesive is a vinylidene fluoride-butadiene-acrylic acid copolymer manufactured by a conventional method, and its synthesis method is as follows: 30 kg of deionized water (conductivity of 2 μs / cm or less), 21 g of alkali metal perfluorooctanoate, and 71.4 g of a 5% potassium persulfate solution are sequentially added to the reaction vessel, and the reaction vessel is closed. The inside of the vessel is evacuated, nitrogen gas is filled in, and this process is repeated until the oxygen concentration inside the reaction vessel falls below 100 ppm. Vinylidene fluoride monomer, butadiene monomer, and 720 g of acrylic acid monomer were introduced into the reaction vessel until the internal pressure reached 7.5 MPa. At this point, the molar ratio of vinylidene fluoride monomer to butadiene monomer was 8:1. The reaction was initiated by raising the temperature inside the vessel to 85°C. During the reaction, vinylidene fluoride monomer and butadiene monomer were continuously introduced to maintain a constant reaction pressure inside the vessel. The total masses of the introduced vinylidene fluoride monomer and butadiene monomer were 5120g and 540g, respectively. When the reaction is complete, the pressure inside the vessel is reduced to 0.0-0.5 MPa, the unreacted butadiene monomer is recovered and reacted, and the product is aggregated, washed, separated, dried, and pulverized to obtain a vinylidene fluoride-butadiene-acrylic acid copolymer adhesive.

[0185] In Examples 22-26, the mass content of black zirconia in the slurry was varied, while other parameters remained the same as in Example 6. The specific parameters are shown in Table 3.

[0186] In Comparative Example 1, the vinylidene fluoride polymer used as the adhesive was the HSV900 model from Acoma, a French company.

[0187] In Comparative Example 2, the adhesive was a vinylidene fluoride-butadiene copolymer, and its synthesis method was almost the same as in Example 1. The difference was that when the introduced vinylidene fluoride monomer was 80% of the total mass of vinylidene fluoride monomer, 30.6 g of a 5% potassium persulfate solution and 19.2 g of a 5% sodium thiosulfate solution were added, and a mixed gas of vinylidene fluoride monomer and butadiene was introduced into the reaction vessel while maintaining the reaction pressure. At this point, the mass of butadiene in the mixed gas was 2160 g, and the mass of vinylidene fluoride monomer was 756.7 g.

[0188] In Comparative Example 3, the adhesive is a vinylidene fluoride-acrylic acid copolymer, and its synthesis method is almost the same as in Example 1. The difference is that when the introduced vinylidene fluoride monomer accounts for 80% of the total mass of vinylidene fluoride monomer, 30.6 g of a 5% potassium persulfate solution and 19.2 g of a 5% sodium thiosulfate solution are added, and while maintaining the reaction pressure, 2880 g of acrylic acid is added to the reaction vessel, and 756.7 g of vinylidene fluoride monomer is continuously introduced.

[0189] In Comparative Example 4, the adhesive is a vinylidene fluoride-butadiene-acrylic acid copolymer, and its synthesis method is the same as in Example 1, with the molar content of the synthesized monomer adjusted. See Tables 1 and 2 for details.

[0190] The relevant parameters for the insulating coatings in Examples 1-26 and Comparative Examples 1-4 are shown in Tables 1, 2, and 3 below.

[0191] 2.Measurement method

[0192] Performance measurements will be performed on the insulating coatings obtained in Examples 1-26 and Comparative Examples 1-4 described above. The measurement method is as follows.

[0193] 1. Measurement of weight-average molecular weight Measurements are performed using a Waters 2695 isocratic HPLC-type gel chromatograph (differential refractive detector 2141). A suitable column (oil-based: Styragel HT5DMF 7.8*300 mm + Styragel HT4) is selected using a 3.0% polystyrene solution sample as a reference. A 3.0% fluorine-containing polymer solution is prepared in purified N-methylpyrrolidone (NMP) solvent, and the prepared solution is allowed to stand for one day to prepare for use. At the time of measurement, first, tetrahydrofuran is drawn into the syringe, washed, and repeated several times. Next, 5 ml of the experimental solution is drawn into the syringe, the air in the syringe is removed, and the needle tip is wiped. Finally, the sample solution is slowly injected into the inlet. After the reading stabilizes, data is acquired and the weight-average molecular weight is read.

[0194] 2. Measurement of the viscosity of the adhesive solution Dissolve the fluorine-containing polymer in N-methylpyrrolidone (NMP) solvent, place a 7% solids adhesive solution in it, select an appropriate rotor, fix the viscometer, place the adhesive solution below the viscometer, and ensure the slurry just submerges the rotor's scale line. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 62# (500~2500 mPa·s), 63# (2500~10000 mPa·s), rotation speed: 12 revolutions / minute, measurement temperature: 25℃, measurement time: 5 min, read the data after the display stabilizes.

[0195] 3. Measurement of slurry viscosity The viscosity of the slurry is measured using a rotating viscometer. Select the appropriate rotor, fix the viscometer rotor in place, place the slurry below the viscometer, and ensure the slurry is just submerged up to the rotor's scale line. Equipment model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000~10000 mPa·s), 64# (10000~50000 mPa·s), rotation speed: 12 revolutions / min, measurement temperature: 25℃, measurement time: 5 min. Read the data after the display has stabilized.

[0196] 4. Measurement of slurry solid content Method for measuring solid content: Prepare a glass petri dish and record its weight m1. Place a portion of the manufactured slurry into the glass petri dish and record the total weight m2. Place the petri dish containing the slurry into a drying box and heat it at a temperature of 120°C for 1 hour. Weigh the dried petri dish and record its weight m3. The solid content = [(m3-m1) / (m2-m1)] × 100%.

[0197] 5. Measurement of slurry fluidity After letting the slurry stand for 6 hours and 12 hours, take a suitable amount of slurry with a spoon and observe whether the slurry flows smoothly. If the slurry flows smoothly, it is judged as OK. If the flow is not smooth, the slurry appears jelly-like and clumps together, indicating the appearance of gelation, it is judged as NG.

[0198] 6. Measurement of slurry filtration performance First, determine that the filter screen is 200 mesh and cut it to 25cm x 25cm with scissors. Find a clean 500ml beaker and make sure it is clean. Fold the 200 mesh filter screen into a triangle, take 500ml of slurry and pour it into the top of the filter screen, pouring it all in at once, and let the slurry flow from the tip of the filter screen into the beaker, and start recording the time. Record the filtration time for 300ml.

[0199] 7. Measurement of adhesive strength Referring to the international standard GB-T2790-1995 "Experimental Method for 180° Peel Strength of Adhesives," the adhesive strength measurement process for the examples and comparative examples of this application is as follows: A sample with a width of 30 mm and a length of 100-160 mm is cut with a blade, and special double-sided tape is attached to the steel plate. The tape has a width of 20 mm and a length of 90-150 mm. The insulating coated surface of the electrode sheet sample cut above is attached to the double-sided tape, and then rolled three times in the same direction with a 2 kg press roll. A paper tape with the same width as the electrode sheet and a length of 250 mm is fixed to the electrode sheet current collector and secured with wrinkle rubber. The power supply (sensitivity of 1 N) of the tensioning machine (manufactured by Shenzhen Sansi) is turned on, the lamp lights up, the stopper is adjusted to the appropriate position, and the end of the steel plate that does not have the electrode sheet attached is fixed with a lower jig. The paper tape is folded upwards and secured with the upper jig. The position of the upper jig is then adjusted using the "up" and "down" buttons on the manual controller attached to the tensioning machine. After that, the measurement is taken and the value is read, indicating a tensioning speed of 50 mm / min. The adhesive strength of the insulating coating per unit length is expressed by dividing the force applied to the electrode sheet when the forces are balanced by the width of the tape, and this indicates the adhesive strength between the insulating coating and the current collector.

[0200] 8. Measurement of laser cutting A laser dicer (manufactured by Han's Laser Technology Industry Group) is used, with the laser output power set to 80% of the maximum output power and the laser frequency set to 1000 kHz. The maximum cutting speed and cutting quality are compared when cutting electrode sheets coated with an insulating coating in different embodiments. If the CCD camera on the dicer can recognize the material, it is judged as Y; if the CCD camera on the dicer cannot recognize the material, it is judged as N. After laser cutting, the cross-sectional shape is observed with an optical microscope. If metal burrs are clearly present on the cross-section after cutting, it is judged as failing; if there are no clear metal burrs on the cross-section after cutting, it is judged as passing. Samples are taken from 100 batches of cut products, and the pass rate for 100 batches is calculated.

[0201] [Table 1-1]

[0202] [Table 1-2]

[0203] [Table 2-1]

[0204] [Table 2-2]

[0205] [Table 3]

[0206] Figure 8 shows a microscopic image of an electrode sheet coated with an insulating coating in Example 26 after laser cutting, where Figure 8A is a plan view of the electrode sheet cutout and Figure 8B is a cross-sectional view of the electrode sheet cutout. Figure 9 shows a microscopic image of an electrode sheet in Example 6 after laser cutting, where Figure 9A is a plan view of the electrode sheet cutout and Figure 9B is a cross-sectional view of the electrode sheet cutout. As can be seen from the comparison of Figures 8 and 9, the electrode sheet with black zirconia added to the insulating coating shows a significant reduction in the amount and length of burrs after laser cutting, effectively improving the laser cutting quality of the electrode sheet.

[0207] As can be seen from the results in Table 1, the adhesives in Examples 1 to 21 are all fluorine-containing polymers, containing structural units derived from vinylidene fluoride, structural units derived from olefins (butadiene or propylene), and structural units derived from acrylic acid. The molar content of structural units derived from vinylidene fluoride in the polymer is 60% to 80% of the total number of moles of structural units in the fluorine-containing polymer. When the above fluorine-containing polymers are used as adhesives, good effects are obtained in all cases. Compared with the conventional PVDF adhesive in Comparative Example 1 and the fluorine-containing polymer with a mass content of vinylidene fluoride-derived structural units of 90% in Comparative Example 4, the fluorine-containing polymer according to the present application improves both the filterability and fluidity of the slurry after standing for 6 hours. Comparing the vinylidene fluoride-butadiene copolymer and vinylidene fluoride-acrylic acid copolymer in Comparative Examples 2 and 3, the fluorine-containing polymer disclosed in the present application comprehensively improves the fluidity, filterability, and adhesive performance of the slurry, achieving both processing performance and usability of the slurry.

[0208] As can be seen from the comparison between Examples 1-3, 5-7 and Example 4, when the molar content of structural units derived from acrylic acid in the fluorine-containing polymer is 5% to 20% of the total number of moles of all structural units in the fluorine-containing polymer, the fluorine-containing polymer improves the fluidity of the slurry after standing for 12 hours and further widens the process window of the slurry.

[0209] As can be seen from the comparison between Examples 2-7 and Example 1, when the molar content of structural units derived from olefin monomers in the fluorine-containing polymer is 5% to 30% of the total number of moles of all structural units in the fluorine-containing polymer, the fluorine-containing polymer improves the processing performance of the slurry while also providing adhesive strength.

[0210] As can be seen from the comparison of Examples 8 to 11, when the weight-average molecular weight of the fluorine-containing polymer is between 500,000 and 800,000, the fluorine-containing polymer comprehensively improves the fluidity, filterability, and adhesion performance of the slurry, thereby achieving both processing performance and usability of the slurry.

[0211] As can be seen from Examples 1 to 20, the viscosity of the adhesive solution containing the fluorine-containing polymer, prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone and having a mass content of 7%, is 2500 to 5000 mPa·s. This eliminates the need to add additional dispersants or thickeners to the slurry of insulating coatings produced by the fluorine-containing polymer to improve processing performance, thereby improving production efficiency and optimizing the production process.

[0212] As can be seen from a comparison of Example 6 and Example 21, the fluorine-containing polymer produced by the method disclosed herein can effectively improve the filterability and fluidity of the slurry and improve the processing performance of the slurry compared to fluorine-containing adhesives synthesized by conventional methods.

[0213] As can be seen from the comparison between Examples 6, 22-25 and Example 26, by adding black zirconia to the insulating coating, the electrode sheet reduces burrs generated at the edges during laser cutting, improving the quality of the laser cutting of the electrode sheet and thus improving the quality of the electrode sheet.

[0214] As can be seen from the comparison between Examples 6, 23-24 and Examples 22, 25, when the mass content of black zirconia in the insulating coating is 0.2% to 3%, the laser cutting speed is improved, production efficiency is further enhanced, and productivity is increased. Furthermore, the color difference between the insulating coating and the positive electrode active material layer allows the laser cutting equipment to accurately position and recognize the material, improving processing accuracy.

[0215] It is important to note that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and any embodiment that exhibits a similar configuration and similar effects to the technical concept within the scope of the technical solution of this application should be included within the scope of this application. Furthermore, other forms that are constructed by combining various components of the embodiments, or by implementing various modifications that a person skilled in the art could conceive of, without departing from the spirit of this application, are also included within the scope of this application. [Explanation of Symbols]

[0216] 1 Battery pack 2 Upper box 3 Lower box 4 Battery Modules 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cover Plate 6 Electrode Sheets 61 Current collector 62 Active material layer 63 Insulating Coating

Claims

1. A fluorine-containing polymer comprising structural units derived from a monomer represented by formula I, structural units derived from an olefin monomer, and structural units derived from a monomer represented by formula II, wherein the molar content of the structural units derived from the monomer represented by formula I is 60% to 80% of the total number of moles of structural units in the fluorine-containing polymer. 【Chemistry 1】 Here, R １ , R ２ , R ３ Each of these independently contains hydrogen, fluorine, chlorine, or at least one fluorine atom. １－３ Selected from alkyl groups, R ４ , R ５ , R ６ Each is independently of hydrogen, or substituted or unsubstituted C １－５ Selected from alkyl groups, The olefin monomer is characterized by being selected from one or more of propylene, 2-butene, and butadiene. A fluorine-containing polymer used for insulating coatings on current collectors.

2. The aforesaid R １ is fluorine, and R ２ , R ３ are each independently selected from hydrogen, fluorine, chlorine or a trifluoromethyl group, and R ５ , R ６ are each independently selected from hydrogen or a methyl group, The fluorine-containing polymer according to Claim 1, characterized by this.

3. The fluorine-containing polymer according to claim 1, characterized in that the molar content of structural units derived from the monomer represented by formula II is 5% to 25% of the total number of moles of all structural units in the fluorine-containing polymer.

4. The fluorine-containing polymer according to claim 1, characterized in that the molar content of structural units derived from the olefin monomer is 5% to 30% of the total number of moles of all structural units in the fluorine-containing polymer.

5. The fluorine-containing polymer according to claim 1, characterized in that the weight-average molecular weight of the fluorine-containing polymer is 500,000 to 800,000.

6. The fluorine-containing polymer according to claim 1, characterized in that the viscosity of the adhesive solution prepared by dissolving the fluorine-containing polymer in N-methylpyrrolidone is 1,000 to 3,000 mPa·s, and the mass content of the fluorine-containing polymer in the adhesive solution is 7% of the total mass of the adhesive solution.

7. The fluorine-containing polymer according to claim 1, characterized in that the monomer represented by formula I is selected from one or more of vinylidene fluoride, tetrafluoroethylene, trifluorochloroethylene, and hexafluoropropylene.

8. The fluorine-containing polymer according to claim 1, characterized in that the monomer represented by formula II is selected from one or two of acrylic acid and methacrylic acid.

9. A method for producing a fluorine-containing polymer used for insulating coating of a current collector, The process includes the step of polymerizing at least one monomer represented by formula I, at least one olefin monomer, and at least one monomer represented by formula II under polymerizable conditions to produce a fluorine-containing polymer, wherein the molar content of the monomer represented by formula I is 60% to 80% of the total number of moles of the monomer represented by formula I, the olefin monomer, and the monomer represented by formula II. 【Chemistry 2】 Here, R １ , R ２ , R ３ Each of these independently contains hydrogen, fluorine, chlorine, or at least one fluorine atom. １－３ Selected from alkyl groups, R ４ , R ５ , R ６ These are, independently, hydrogen, substituted or unsubstituted C １－５ Selected from alkyl groups, A method for producing a fluorine-containing polymer, characterized in that the olefin monomer is selected from one or more of propylene, 2-butene, and butadiene.

10. The aforementioned R １ is fluorine, R ２ , R ３ Each is independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl groups, R ５ , R ６ The manufacturing method according to claim 9, characterized in that each is independently selected from one or two of hydrogen and methyl groups.

11. The polymerization reaction includes a first-step polymerization and a second-step polymerization. In the first-stage polymerization, a first initiator, an emulsifier, at least one monomer represented by formula I, and a solvent are provided to carry out the first-stage polymerization, and during the process of the first-stage polymerization, the monomer represented by formula I is continuously supplied to maintain the initial reaction pressure, the initial reaction pressure of the first-stage polymerization is 5.5 MPa to 7.5 MPa. The manufacturing method according to claim 9, characterized in that, in the second stage polymerization, after reacting for a certain period of time, an olefin monomer and a monomer represented by formula II are introduced into the reaction vessel to carry out the second stage polymerization, and when the pressure in the reaction vessel drops to 0.5 MPa or less, the reaction is stopped, the solid and liquid are separated, and the solid phase remains.

12. The manufacturing method according to claim 11, characterized in that the reaction temperature of the first step polymerization is 70°C to 90°C.

13. The aforementioned second step polymerization is If the mass of the monomer represented by formula I that is introduced is 70% to 85% of the total mass of the monomer represented by formula I supplied to the polymerization reaction process, the reaction is continued by introducing a mixed gas of the monomer represented by formula I and the olefin monomer into the reaction vessel and maintaining the initial reaction pressure. The manufacturing method according to claim 11, characterized by comprising the step of sending all of the monomer represented by formula I into a reaction vessel, and then sending a mixture of an olefin monomer and a monomer represented by formula II into the reaction vessel.

14. The manufacturing method according to claim 9, characterized in that the ratio of the total number of moles of olefin monomers supplied in the polymerization reaction process to the total number of moles of monomers represented by formula I is 1:16 to 1:

2.

15. The manufacturing method according to claim 9, characterized in that the ratio of the total number of moles of the monomer represented by formula II supplied in the polymerization reaction process to the total number of moles of the monomer represented by formula I is 1:16 to 1:

3.

16. The manufacturing method according to claim 13, characterized in that the molar ratio of the olefin monomer to the monomer represented by formula I in the mixed gas is 1:1 to 2:

1.

17. The manufacturing method according to claim 13, characterized in that the molar ratio of the olefin monomer to the monomer represented by formula II in the mixture is 3:1 to 4:

1.

18. The aforementioned second step polymerization is The manufacturing method according to claim 13, further comprising the step of adding a first initiator and a second initiator to the reaction vessel before introducing a mixed gas of the monomer represented by formula I and an olefin monomer into the reaction vessel.

19. The aforementioned second step polymerization is The method for producing the product according to claim 13, further comprising the step of adding a second initiator to the reaction vessel before introducing a mixture of an olefin monomer and a monomer represented by formula II into the reaction vessel.

20. The manufacturing method according to claim 18, characterized in that the first initiator is a persulfate.

21. The manufacturing method according to claim 20, characterized in that the persulfate is selected from one or more types of potassium persulfate and ammonium persulfate.

22. The manufacturing method according to claim 18, characterized in that the second initiator is a thiosulfate.

23. The manufacturing method according to claim 22, characterized in that the thiosulfate is selected from sodium thiosulfate.

24. Use of the fluorine-containing polymer described in claim 1 in a secondary battery.

25. An insulating coating comprising an adhesive and an inorganic insulating material, wherein the adhesive is a fluorine-containing polymer as described in claim 1.

26. The insulating coating according to claim 25, characterized in that the mass content of the adhesive is 7.0% to 13.0% of the total mass of the insulating coating.

27. The insulating coating according to claim 25, characterized in that the inorganic insulating material includes a colored oxide, and the colored oxide is selected from one or more types of black zirconia, yellow zirconia, red zirconia, and green zirconia.

28. The insulating coating according to claim 27, characterized in that the mass content of the colored oxide is 0.2% to 3% of the total mass of the insulating coating.

29. A method for manufacturing an insulating coating, A step of preparing an adhesive solution by dispersing the adhesive, which is a fluorine-containing polymer according to claim 1, in a solvent, A step of mixing an inorganic insulating material with the adhesive solution and stirring to produce a slurry having a solid content of 30% to 40%, A method for manufacturing an insulating coating, comprising the step of coating a current collector with the slurry to produce an insulating coating.

30. The method for manufacturing an insulating coating according to claim 29, characterized in that the viscosity of the slurry is 2,500 to 4,000 mPa·s.

31. The step of mixing the inorganic insulating material with the adhesive solution is, The method for producing an insulating coating according to claim 29, characterized by comprising the step of mixing an inorganic insulating material other than a colored oxide with the adhesive solution, stirring, adding the colored oxide, and stirring again to produce the slurry.

32. A secondary battery comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, wherein the positive electrode sheet and / or the negative electrode sheet include the insulating coating described in claim 25.

33. The secondary battery according to claim 32, characterized in that it includes at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery.

34. A battery module characterized by comprising the secondary battery described in claim 32.

35. A battery pack characterized by comprising the secondary battery described in claim 32.

36. A power consumption device comprising at least one selected from the secondary battery described in claim 32 or claim 33, the battery module described in claim 34, and the battery pack described in claim 35.

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