BAB-type block copolymer, manufacturing method, positive electrode plate, secondary battery, battery module, battery pack, and power consumption device.

Abstract

The present application provides a BAB-type block copolymer, a production method, a positive electrode plate, a secondary battery, a battery module, a battery pack, and an electric power consumption device. The BAB-type block copolymer includes a B-block and an A-block. The B-block contains a structural unit represented by Formula I, and the A-block contains one or more of a structural unit represented by Formula II and a structural unit represented by Formula III. Here, R 1 , R 2 , R 3 are each independently one or more selected from hydrogen, fluorine, and 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 and a substituted or unsubstituted C 1-5 alkyl group, and R 7 is selected from a carboxyl group, an ester group, a hydroxyl group, an amide group, a cyano group, and a substituted or unsubstituted aromatic group.

Description

[Technical Field]

[0001] This application relates to the field of secondary battery technology, and more particularly to BAB-type block copolymers, manufacturing methods, positive electrode plates, secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] In recent years, rechargeable batteries have been widely applied in numerous fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the increasing prevalence of rechargeable battery applications, higher demands are being placed on their energy density and cycle performance.

[0003] Adhesives are commonly used materials in secondary batteries, and are widely applied in battery electrodes, separators, and packaging. However, conventional adhesives have high production costs, insufficient production capacity, significant environmental hazards, and are prone to gel formation during manufacturing, resulting in poor slurry stability and high processing costs. Electrodes manufactured with these adhesives have poor conductivity, high resistance, low yield rates, and unstable battery performance, making it difficult to meet market demands for battery cost and performance. Therefore, there is still room for improvement in conventional adhesives. [Overview of the Initiative]

[0004] This application has been made in view of the above problems and aims to provide a BAB-type block copolymer. By using this block copolymer as an adhesive, the adhesive strength of the electrode plates can be effectively improved, the DC impedance growth rate and metal deposition amount of the battery can be reduced, low film resistance and excellent flexibility can be achieved in the electrode plates, and a high cycle capacity retention rate and 45°C capacity retention rate can be achieved in the battery.

[0005] A first aspect of this application provides a BAB-type block copolymer, wherein the B-block contains a structural unit shown in formula I, and the A-block contains one or more of the structural units shown in formula II and the structural units shown in formula III. JPEG0007844677000001.jpg60170 Here, R1, R2, and R3 are each independently hydrogen, fluorine, and C containing at least one fluorine atom. 1-3 R4, R5, and R6 are one or more selected alkyl groups, and each is independently hydrogen, substituted, or unsubstituted C. 1-5 Selected from alkyl groups, R7 is selected from carboxyl groups, ester groups, hydroxyl groups, amide groups, cyano groups, and substituted or unsubstituted aromatic groups.

[0006] Adhesives manufactured from BAB-type block copolymers effectively reduce the orderly arrangement of fluorine-containing block polymers because the non-fluorine block polymer is positioned between the fluorine-containing block polymers. Furthermore, by introducing functional groups into the non-fluorine-containing polymer, the adhesive performance of the BAB-type block copolymer is improved, allowing the advantages of both fluorine-containing and non-fluorine adhesives to be fully realized and their advantages to complement each other. Compared to conventional PVDF adhesives, this adhesive effectively improves the adhesive strength of the electrode plates, reduces the DC impedance growth rate and metal deposition amount of the battery, and achieves both low film resistance and excellent flexibility in the electrode plates, ensuring that the battery achieves both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0007] In any embodiment, the A-block contains a structural unit represented by formula II, wherein R7 is an amide group.

[0008] The inclusion of the structural unit shown in Formula II, in which R7 is an amide group, in Block A is advantageous in improving the adhesion and flexibility of the electrode plate, reducing the film resistance of the electrode plate, and significantly reducing the elution of the transition metal at the positive electrode.

[0009] In some embodiments, the A-block contains a structural unit represented by Formula II where R7 is a cyano group and a structural unit represented by Formula II where R7 is an ester group.

[0010] The simultaneous inclusion of a structural unit represented by Formula II where R7 is a cyano group and a structural unit represented by Formula II where R7 is an ester group in the A-block is advantageous in improving the adhesion and flexibility of the electrode plate, reducing the membrane resistance of the electrode plate, reducing the DC impedance growth rate and the amount of metal deposition of the battery, and ensuring the coexistence of a high cycle capacity retention rate and a 45°C capacity retention rate in the battery.

[0011] In some embodiments, the A-block contains a structural unit represented by Formula II where R7 is a cyano group, a structural unit represented by Formula II where R7 is an ester group, and a structural unit represented by Formula II where R7 is a substituted or unsubstituted aromatic group.

[0012] According to the applicant's unexpected discovery, the simultaneous inclusion of a structural unit represented by Formula II where R7 is a cyano group, a structural unit represented by Formula II where R7 is an ester group, and a structural unit represented by Formula II where R7 is a substituted or unsubstituted aromatic group in the A-block is advantageous in further improving the adhesion and flexibility of the electrode plate and the cycle capacity retention rate and 45°C capacity retention rate of the battery.

[0013] In some embodiments, the A-block contains a structural unit represented by Formula II where R7 is a cyano group, a structural unit represented by Formula II where R7 is an amide group, and a structural unit represented by Formula II where R7 is an ester group.

[0014] The simultaneous inclusion of a structural unit represented by Formula II where R7 is a cyano group, a structural unit represented by Formula II where R7 is an amide group, and a structural unit represented by Formula II where R7 is an ester group in the A-block ensures the coexistence of a low membrane resistance, excellent adhesion and flexibility in the electrode plate, and at the same time can significantly reduce the amount of metal deposition in the battery.

[0015] In any embodiment, the mass content of the A-block is 40% to 60% based on the total mass of all structural units in the block copolymer.

[0016] By controlling the mass content of the structural unit shown in formula I in the BAB-type block copolymer within an appropriate range, the adhesive can effectively improve the adhesive strength and flexibility of the electrode plates, reduce the film resistance of the electrode plates, increase the battery's cycle capacity retention rate and 45°C capacity retention rate, and reduce the battery's DC impedance growth rate and metal deposition amount.

[0017] In any of the embodiments, the weight-average molecular weight of the block copolymer is between 400,000 and 2,000,000.

[0018] By controlling the weight-average molecular weight of the block copolymer within an appropriate range, the adhesive can improve the adhesion strength of the electrode plates, reduce the DC impedance growth rate and metal deposition amount of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0019] In any embodiment, the weight-average molecular weight of the A-block in the block copolymer is between 200,000 and 1,100,000.

[0020] By controlling the weight-average molecular weight of A-blocks in the block copolymer within an appropriate range, the adhesive can improve the adhesion strength of the electrode plates, reduce the DC impedance growth rate and metal deposition amount of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0021] In any embodiment, the weight-average molecular weight of each B-block in the block copolymer is between 100,000 and 500,000.

[0022] By controlling the weight-average molecular weight of each B-block in the block copolymer within an appropriate range, the adhesive can improve the adhesion strength of the electrode plates, reduce the DC impedance growth rate and metal deposition amount of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0023] In any embodiment, the structural unit shown in formula I is derived from the group consisting of vinylidene fluoride, tetrafluoroethylene, vinyl fluoride, hexafluoropropene, and combinations thereof.

[0024] In any embodiment, the structural unit shown in formula II is derived from the group consisting of acrylonitrile, crotononitrile, styrene, vinyl alcohol, acrylamide, ethyl acrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid, ethacrylic acid, methacrylamide, N-methacrylamide, N-methylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, Nt-butylacrylamide, Nt-butyl(meth)acrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, acrylic acid, vinylbenzoic acid, acrylic acetate, acrylic acid esters, and combinations thereof.

[0025] The above raw materials are simple and readily available, and production costs can be significantly reduced compared to conventional adhesives.

[0026] A second aspect of this application further provides a method for producing a BAB-type block copolymer, the method being: A B-block is produced by polymerizing at least one monomer shown in formula V, JPEG0007844677000002.jpg25170 Here, R′1, R′2, and R′3 are each independently hydrogen, fluorine, and C containing at least one fluorine atom. 1-3A manufacturing step of a B-block which is one or more selected from alkyl groups, A block is produced by polymerizing at least one monomer shown in formula VI, or by ring-opening polymerization of a monomer shown in formula VII. JPEG0007844677000003.jpg39170 Here, R'4, R'5, and R'6 are each independently hydrogen, substituted, or unsubstituted C 1-5 The manufacturing step of block A is to select from alkyl groups, and R'7 is one selected from a carboxyl group, ester group, hydroxyl group, amide group, cyano group, or substituted or unsubstituted aromatic group, The process includes a step of producing a BAB-type block copolymer by combining the B-block and the A-block to produce a BAB-type block copolymer.

[0027] This manufacturing method maximizes the weight-average molecular weight of fluorine-containing blocks and non-fluorine blocks compared to conventional copolymerization methods, fully utilizing the advantages of both fluorine-containing and non-fluorine adhesives and achieving a complementary effect of their respective advantages. The BAB-type triblock copolymer adhesive produced by this method effectively improves the adhesive strength of the electrode plates, reduces the DC impedance growth rate and metal deposition amount of the battery, and ensures that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0028] In any embodiment, the manufacturing step of the B-block is: The method includes reacting at least one monomer represented by formula V, a chain transfer agent, and a first initiator with a B-block having an azide group or an alkynyl group at the terminal end by reversible addition-cleavage chain transfer polymerization at a reaction temperature of 60-75°C for 4-6 hours.

[0029] By employing this manufacturing method, controllable polymerization can be achieved, and the molecular weight distribution of the product is narrow.

[0030] In any embodiment, the manufacturing step of the A-block is: The method includes polymerizing a monomer shown in formula VI with a second initiator at a reaction temperature of 80 to 95°C for 2.5 to 5 hours to obtain the A-block having either an alkynyl group or an azide group at both ends.

[0031] By employing this manufacturing method, we succeed in producing A-blocks having azide or terminal alkynyl groups at both ends.

[0032] In any embodiment, the manufacturing step of the A-block is: The monomer shown in formula VII, an ion initiator, and water are polymerized at a reaction temperature of 60°C-80°C for 6-8 hours to obtain a product having hydroxyl groups at both ends. The process involves functionalizing the hydroxyl group of the product to obtain the A-block having either an alkynyl group or an azide group at both ends.

[0033] By employing this manufacturing method, we succeed in producing A-blocks having azide or terminal alkynyl groups at both ends.

[0034] In any embodiment, the production of the BAB-type block copolymer is The process involves mixing the A-block, which has an azide group or an alkynyl group at both ends, with the B-block, which has an alkynyl group or an azide group at its end, and performing a click reaction to produce a BAB-type block copolymer, wherein the terminal groups of the A-block and the B-block are different.

[0035] The above manufacturing method has the advantages of being highly efficient, stable, and highly specific, thereby improving the yield rate of the product.

[0036] In any embodiment, the chain transfer agent is a RAFT chain transfer agent containing a terminal alkynyl group or azide group.

[0037] In any embodiment, the second initiator is a symmetrical bifunctional initiator.

[0038] In any embodiment, the first initiator is one or two selected from azobisisobutyronitrile and azobisisoheptonitrile.

[0039] A third aspect of this application provides an application of a BAB-type block copolymer in a secondary battery in any of its embodiments.

[0040] A fourth aspect of this application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, a conductive agent, and an adhesive, the adhesive being a BAB-type block copolymer according to any embodiment or a BAB-type block copolymer produced by a manufacturing method according to any embodiment.

[0041] The positive electrode plate has low film resistance, excellent adhesion, and good flexibility, while the battery has low metal deposition, excellent cycle performance, and high-temperature storage performance.

[0042] In any embodiment, the adhesive strength per unit length between the positive electrode film layer and the positive electrode current collector is 11 N / m or more. The adhesive strength between the positive electrode film layer and the positive electrode current collector of the electrode plate is high, making it difficult for the positive electrode film layer to detach from the positive electrode current collector during use, which contributes to improving the battery's cycle performance and safety.

[0043] In any embodiment, the positive electrode plate undergoes a light transmission phenomenon after undergoing three or more bending tests. The ability of the electrode plate to undergo three or more bending tests indicates that the electrode plate has good flexibility, is less likely to collapse during production, and is less likely to experience brittle fracture during use, thereby contributing to an improved yield rate of batteries and enhanced safety performance.

[0044] In any embodiment, the film resistance of the positive electrode plate is 1.0 Ω or less. Having a low film resistance of the electrode plate indicates that the dispersion of materials in the positive electrode film layer is uniform, and having good electron transmission efficiency in the positive electrode film layer is advantageous for achieving battery performance.

[0045] A fifth aspect of this application provides a secondary battery comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a separator, a negative electrode plate, and a positive electrode plate according to a fourth aspect of this application.

[0046] A sixth aspect of this application provides a battery module, which includes a secondary battery according to a fifth aspect of this application.

[0047] A seventh aspect of this application provides a battery pack, which includes a battery module according to a sixth aspect of this application.

[0048] An eighth aspect of this application provides a power consumption device comprising at least one of a secondary battery according to the fifth aspect of this application, a battery module according to the sixth aspect, or a battery pack according to the seventh aspect. [Brief explanation of the drawing]

[0049] [Figure 1] This is a schematic diagram of the manufacturing process of a BAB-type block copolymer according to one embodiment of this application. [Figure 2] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 3] Figure 2 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 4] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 5] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 6] Figure 5 is an exploded view of a battery pack according to one embodiment of this application. [Figure 7] This is a schematic diagram of a power consumption device in which a secondary battery is used as a power source according to one embodiment of this application. [Modes for carrying out the invention]

[0050] In the following, embodiments specifically disclosing the positive electrode active material and its manufacturing method, positive electrode plate, secondary battery, battery module, battery pack, and electrical device of this application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the topics described in the claims.

[0051] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, 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 can also be assumed. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0053] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0054] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that 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 fact that the method mentioned above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0055] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may be open or closed. For example, “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0056] 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, the conditions A is true (or exists) and B is false (or does not exist), the condition A is false (or does not exist) but B is true (or exists), and the condition both A and B are true (or exist) all satisfy "A or B."

[0057] Conventional technologies consistently use polyvinylidene fluoride (PVDF) as an electrode adhesive. However, PVDF has many problems. For example, it is sensitive to water content during production, generates large amounts of HF during battery recovery, pollutes the environment, and is restricted by environmental protection policies, preventing large-scale recycling. Furthermore, in the process of manufacturing a positive electrode slurry by mixing it with high-capacity positive electrode active material (e.g., high-nickel ternary material), the strong polar groups on PVDF activate hydroxyl groups remaining on the positive electrode active material, which then bond with metal elements (e.g., nickel) in the positive electrode active material, forming chemical crosslinks and ultimately causing a slurry gel, affecting the normal production of the slurry and subsequent electrode plate processing. In addition, PVDF is prone to crystallization, which is unfavorable for electron transmission on the electrode plate. Moreover, it increases the resistance of the electrode plate, worsening electron transmission performance and hindering the performance of high-capacity positive electrode active materials.

[0058] [glue] Based on this, this application proposes a BAB-type block copolymer in which the B-block contains the structural unit shown in formula I, and the A-block contains one or more of the structural units shown in formula II and the structural units shown in formula III. JPEG0007844677000004.jpg60170 Here, R1, R2, and R3 are each independently hydrogen, fluorine, and C containing at least one fluorine atom. 1-3 R4, R5, and R6 are one or more selected alkyl groups, and each is independently hydrogen, substituted, or unsubstituted C. 1-5 Selected from alkyl groups, R7 is selected from carboxyl groups, ester groups, hydroxyl groups, amide groups, cyano groups, and substituted or unsubstituted aromatic groups.

[0059] In this specification, the term "block copolymer" refers to a special polymer produced by linking two or more polymer segments with different properties. Block polymers with specific structures exhibit different properties from simple linear polymers, many random copolymers, and mixtures of homopolymers. Common types include AB and BAB types, where A and B are both long-chain segments, and (AB)n type multiblock copolymers, where A and B segments are relatively short.

[0060] In this specification, the term "BAB-type block copolymer" refers to a triblock copolymer having an A-block in the middle and B-blocks on both sides. Here, the A-block and B-block are polymer segments having a predetermined weight-average molecular weight, formed by polymerizing different monomers. In some embodiments, the B-block is a long sequence segment formed by polymerizing fluorine-containing monomers, and the A-block is a long sequence segment formed by polymerizing one or more fluorine-free monomers. The A-block and B-block are bonded together in an orderly manner via covalent bonds to form a BAB-type block copolymer. Taking the BAB-type block polymer produced in Example 1 as an example, here, A-block poly(acrylonitrile-butyl methacrylate-styrene) is formed by polymerizing acrylonitrile monomer, butyl methacrylate monomer, and styrene monomer, and has a weight-average molecular weight of 480,000. B-block is polyvinylidene fluoride, formed by polymerizing vinylidene fluoride monomer, and has a weight-average molecular weight of 400,000. By joining the terminal groups on both sides of B-block and A-block, a polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer (BAB-type block copolymer) is obtained, and the weight-average molecular weight of this block copolymer is 1,200,000.

[0061] As used herein, the term "polymer" includes an aggregate of macromolecules that are chemically uniform but have different degrees of polymerization, mass contents, and chain lengths, and are produced by a polymerization reaction. Meanwhile, the term also includes derivatives of such macromolecular aggregates formed by a polymerization reaction, i.e., those obtained by reactions of functional groups in the above macromolecules, such as addition or substitution, and may be compounds that are chemically uniform or chemically non-uniform.

[0062] As used herein, the term "C" 1-3 "alkyl group" refers to a straight-chain or branched-chain hydrocarbon group composed of only carbon and hydrogen atoms, having no unsaturation in the group, having 1 to 3 carbon atoms, and being linked to the other part of the molecule through a single bond. C 1-3 Examples of C alkyl groups include, but are not limited to, methyl group, ethyl group, n-propyl group, 1-methylethyl group (isopropyl group).

[0063] As used herein, the term "C" 1-5 "alkyl group" refers to a straight-chain or branched-chain hydrocarbon group composed of only carbon and hydrogen atoms, having no unsaturation in the group, having 1 to 5 carbon atoms, and being linked to the other part of the molecule through a single bond. C 1-5 Examples of C alkyl groups include, but are not limited to, methyl group, ethyl group, n-propyl group, 1-methylethyl group (isopropyl group), n-butyl group, n-pentyl group.

[0064] As used herein, the term "carboxyl group" refers to the -COOH group.

[0065] As used herein, the term "ester group" refers to the -COOR 10 group, where R 10 is selected from substituted or unsubstituted C 1-5 alkyl groups.

[0066] As used herein, the term "hydroxyl group" refers to the -OH group.

[0067] In this specification, the term "amide group" refers to the -CO-NR8R9 group, where R8 and R9 are independently substituted or unsubstituted C. 1-5 Selected from alkyl groups.

[0068] In this specification, the term "cyano group" refers to the -CN group.

[0069] In this specification, the term “substituted” means that at least one hydrogen atom of the compound or chemical part is substituted by another chemical part, substituent, where each substituent is independently a hydroxyl group, mercapto group, amino group, cyano group, nitro group, aldehyde group, halogen atom, alkenyl group, alkynyl group, aryl group, heteroaryl group, C 1-6 Alkyl alkyl group, C 1-6 Selected from alkoxy groups.

[0070] In some embodiments, BAB-type block copolymers are used as electrode adhesives.

[0071] 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.

[0072] In some embodiments, the dispersion medium for the adhesive is an aqueous solvent, such as water. That is, the adhesive dissolves in the aqueous solvent.

[0073] In some embodiments, the dispersion medium for the adhesive is an oily solvent, and examples of oily solvents include, but are not limited to, dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, acetone, dimethyl carbonate, ethylcellulose, and polycarbonate. That is, the adhesive dissolves in the oily solvent.

[0074] In some embodiments, adhesives are used to fix electrode materials and / or conductive agents in the appropriate positions and to adhere them to a conductive metal member to form electrodes.

[0075] In some embodiments, the adhesive is used as a positive electrode adhesive to bond the positive electrode active material and / or conductive agent to form an electrode.

[0076] In some embodiments, the adhesive is used as a negative electrode adhesive to bond the negative electrode active material and / or conductive material to form an electrode.

[0077] The fluorine elements contained in Block B form hydrogen bonds with the hydroxyl groups and / or carboxyl groups on the active material surface and the current collector surface, providing excellent adhesion to the electrode plates. The amide groups, carboxyl groups, ester groups, hydroxyl groups, or cyano groups contained in Block A can, on the one hand, form hydrogen bonds with the hydroxyl groups on the surface of the positive electrode active material and conductive particle surface to improve the adhesion to the electrode plates, and on the other hand, they can effectively bond with the transition metal in the positive electrode active material, suppressing the leaching of the transition metal during use and improving cycle performance. At the same time, the insertion of Block A between Block B can reduce the orderly arrangement of large areas of fluorine-containing segments, reduce crystallinity, and increase flexibility. Adhesives manufactured from BAB-type block copolymers effectively reduce the orderly arrangement of fluorine-containing block polymers because the non-fluorine-containing block polymer is positioned between the fluorine-containing block polymers. Furthermore, by introducing functional groups into the non-fluorine-containing polymer, the adhesive performance of the BAB-type block copolymer is improved, allowing the advantages of both fluorine-containing and non-fluorine adhesives to be fully realized and their advantages to complement each other. Moreover, compared to simple blends of fluorine-containing and non-fluorine polymers, BAB-type block copolymers can effectively suppress the delamination phenomenon that occurs during slurry production due to interactions between the blocks.

[0078] Based on the above, by using a BAB-type block copolymer as an adhesive, the adhesive strength of the electrode plates can be improved, reducing the DC impedance growth rate and the amount of transition metal leaching in the battery. Furthermore, it is possible to achieve both low film resistance and excellent flexibility in the electrode plates, ensuring that the battery has a high cycle capacity retention rate and a 45°C capacity retention rate.

[0079] In this specification, adhesive strength is used primarily to characterize the adhesive strength between a film layer manufactured from a positive electrode slurry on a positive electrode plate and a current collector, which can be tested by any known method.

[0080] In this specification, film resistance is used primarily to characterize the resistance of a positive plate and can reflect the electronic conductivity of the positive plate, which can be tested by any known method.

[0081] In this specification, flexibility is used primarily to characterize the bending resistance of the positive electrode plate and can reflect the malleability of the positive electrode plate, which can be tested by any known method.

[0082] In this specification, the DC impedance growth rate is used primarily to characterize the impedance performance of a battery and can reflect the rate of increase in impedance during the battery cycle, which can be tested by any known method.

[0083] In this specification, cycle performance is used primarily to characterize the cyclic use performance of a battery, and can reflect the cyclic performance of a battery, which can be tested by any known method.

[0084] In this specification, high-temperature storage performance is used primarily to characterize the high-temperature operation performance of a battery and can reflect the high-temperature stability of the battery, which can be tested by any known method.

[0085] In some embodiments, the A-block contains a structural unit shown in formula II, where R7 is an amide group. In some embodiments, R7 in formula II is as shown in formula IV, JPEG0007844677000005.jpg27170 Here, R8 and R9 are, independently, hydrogen and substituted or unsubstituted C, respectively. 1-5 Selected from alkyl groups, The amide groups contained in Block A readily form hydrogen bonds with the hydroxyl groups of the positive electrode active material and current collector, thereby improving the adhesion of the electrode plates. Furthermore, the amide groups contained in Block A can improve the penetration ability of the electrode plates into the electrolyte, contributing to the rapid formation of ion transmission channels on the electrode plates, reducing the film resistance of the electrode plates, and improving the battery's cycle performance.

[0086] The inclusion of the structural unit shown in Formula II, in which R7 is an amide group, in Block A is advantageous in improving the adhesion and flexibility of the electrode plate, reducing the film resistance of the electrode plate, and significantly reducing the elution of the transition metal at the positive electrode.

[0087] In some embodiments, the A-block contains a structural unit shown in formula II in which R7 is a cyano group, and a structural unit shown in formula II in which R7 is an ester group.

[0088] Block A contains cyano groups, which are strong polar groups. These cyano groups can form strong hydrogen bonds and dipole-dipole interactions with hydroxyl groups on the surface of the positive electrode active material. This allows for stabilization and dispersion in the slurry, further improving the adhesion of the electrode plates, promoting the dispersion of the positive electrode active material, and contributing to a reduction in the film resistance of the electrode plates. Furthermore, the cyano groups, being strong polar groups, reinforce the stability of the molecular structure, improve the vitrification transition temperature of the block copolymer, enhance the rigidity and thermal stability of the block copolymer, contribute to improved oxidation stability of the electrode plates, and enhance the battery's cycle and magnification performance. Furthermore, the cyano groups in the A-block provide a certain degree of coverage to the positive electrode active material. The cyano groups in the A-block can complex with transition metal ions on the surface of the positive electrode active material, inhibiting the elution of transition metal ions and further reducing the deposition of transition metal ions on the negative electrode surface. The ester groups contained in the A-block weaken the excessive dipole moment between the cyano groups, reducing the brittleness problem of the electrode plate caused by excessive force between the heavy cyano groups of the A-block hindering the free movement of the adhesive segment, thereby contributing to improved battery safety performance. In addition, the ester groups have good affinity with the electrolyte, contributing to strengthening the contact between the electrolyte and the positive electrode active material, thereby improving ionic conductivity and reducing the film resistance of the electrode plate.

[0089] The simultaneous inclusion of both the structural unit shown in Formula II, in which R7 is a cyano group, and the structural unit shown in Formula II, in which R7 is an ester group, in Block A is advantageous in improving the adhesion and flexibility of the electrode plates, reducing the film resistance of the electrode plates, reducing the DC impedance growth rate and metal deposition amount of the battery, and ensuring that the battery achieves both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0090] In some embodiments, the A-block contains a structural unit shown in formula II in which R7 is a cyano group, a structural unit shown in formula II in which R7 is an ester group, and a structural unit shown in formula II in which R7 is a substituted or unsubstituted aromatic group.

[0091] The aromatic groups contained in Block A contribute to improving the mechanical strength of the electrode plate, thereby accommodating volume changes in the positive electrode active material during charging and discharging, maintaining structural integrity of the electrode during charging and discharging, and improving the battery's cycle performance.

[0092] The simultaneous inclusion of structural units in Block A where R7 is a cyano group, structural units where R7 is an ester group, and structural units where R7 is a substituted or unsubstituted aromatic group is also advantageous in further improving the adhesive strength and flexibility of the electrode plates.

[0093] In some embodiments, the A-block contains a structural unit shown in formula II in which R7 is a cyano group, a structural unit shown in formula II in which R7 is an amide group, and a structural unit shown in formula II in which R7 is an ester group.

[0094] The simultaneous inclusion of structural units in Block A where R7 is a cyano group, structural units where R7 is an amide group, and structural units where R7 is an ester group ensures that the electrode plate exhibits both low film resistance, excellent adhesion, and flexibility, while simultaneously significantly reducing the amount of metal deposited in the battery. This allows the battery to exhibit both a low DC impedance growth rate, a high cycle capacity retention rate, and a high 45°C capacity retention rate.

[0095] In some embodiments, R7 in formula II is optionally one or more of a carboxyl group and a hydroxyl group.

[0096] In some embodiments, the structural unit shown in formula II is derived from the group consisting of acrylonitrile, crotononitrile, styrene, vinyl alcohol, acrylamide, ethyl acrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid, ethacrylic acid, methacrylamide, N-methacrylamide, N-methylmethacrylamide, N-isopropyl acrylamide, N-isopropyl methacrylamide, Nt-butyl acrylamide, Nt-butyl(meth)acrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, acrylic acid, vinyl benzoic acid, acrylic acetate, acrylic acid esters, and combinations thereof.

[0097] In some embodiments, the structural units shown in formula I are derived from the group consisting of vinylidene fluoride, tetrafluoroethylene, vinyl fluoride, hexafluoropropene, and combinations thereof.

[0098] In some embodiments, the BAB block copolymer is polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-polyacrylamide-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-poly(acrylic acid-acrylamide-ethyl methacrylate)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-poly(acrylonitrile-acrylamide-acrylic acid ester)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-polystyrene-polyvinylidene It is one of the following: polyvinylide block copolymer, polyvinylidene fluoride-polyethylene oxide-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-polyvinyl alcohol-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-poly(acrylonitrile-acrylic acetate)-polyvinylidene fluoride block copolymer, polyvinyl fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinyl fluoride block copolymer, and polytetrafluoroethylene-poly(acrylonitrile-butyl methacrylate-styrene)-polytetrafluoroethylene block copolymer.

[0099] In some embodiments, the mass content of A-block is 40% to 60% based on the total mass of the block copolymer. In some embodiments, the mass content of A-block is arbitrarily selected to be 40%, 42%, 44%, 45%, 46%, 48%, 50%, 42%, 54%, 54%, 55%, 56%, 58%, and 60% based on the total mass of the block copolymer.

[0100] BAB-type block copolymers with an appropriate mass content of A-blocks can improve the adhesion and flexibility of electrode plates, reduce the film resistance of electrode plates, increase the battery's cycle capacity retention rate and 45°C capacity retention rate, and reduce the battery's DC impedance growth rate and metal deposition.

[0101] In some embodiments, the weight-average molecular weight of the block copolymer is between 400,000 and 2,000,000. In some embodiments, the weight-average molecular weight of the block copolymer is optionally 400,000, 420,000, 450,000, 480,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, and 2,000,000.

[0102] In this specification, the term "weight-average molecular weight" refers to the sum of the products of the weight fractions of molecules with different molecular weights in a polymer and their corresponding molecular weights.

[0103] In this application, the weight-average molecular weight of the polymer can be tested using methods known in the art, such as gel chromatography, specifically using a Waters 2695 Isocratic HPLC-type gel chromatograph (differential refractive index detector 2141). A 3.0% polystyrene solution sample is used as a reference, and a suitable column (oil-based: Styragel HT5DMF 7.8 × 300 mm + Styragel HT4) is selected. A 3.0% fluorine-containing polymer solution is prepared using purified N-methylpyrrolidone (NMP) solvent, and the prepared solution is allowed to stand for 1 day before use. When testing, first draw up tetrahydrofuran with a syringe, wash, and repeat several times. Then, draw up 5 ml of the experimental solution, expel the air from the syringe, and clean the needle tip. Finally, slowly inject the sample solution into the sample inlet. After the readings stabilize, acquire the data and read the weight-average molecular weight.

[0104] If the weight-average molecular weight of the block copolymer is too high, it becomes difficult to dissolve the adhesive, it tends to aggregate with the conductive agent, the internal resistance of the film increases, and it also increases the viscosity of the slurry, reducing the dispersibility of the material in the slurry and affecting the flexibility of the electrode plate. If the weight-average molecular weight of the block copolymer is too low, it becomes difficult to form a three-dimensional network adhesive structure, and it cannot perform an effective adhesive action.

[0105] BAB block copolymers with a weight-average molecular weight within an appropriate range can improve electrode adhesion, reduce the DC impedance growth rate and metal deposition of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both high cycle capacity retention and 45°C capacity retention.

[0106] In some embodiments, the weight-average molecular weight of A-blocks in the block copolymer is between 200,000 and 1,100,000. In some embodiments, the weight-average molecular weight of A-blocks in the block copolymer is optionally 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1,000,000, 1,050,000, and 1,100,000.

[0107] If the weight-average molecular weight of the A-block in the block copolymer is too high, there will be too many strongly polar groups in the structural units of the monomers shown in formula II or formula III, affecting the stability of the slurry. Conversely, if the weight-average molecular weight of the A-block in the block copolymer is too low, the adhesive strength of the electrode plates will decrease.

[0108] BAB block copolymers in which the weight-average molecular weight of A-block is within an appropriate range can improve the adhesion of the electrode plates, reduce the DC impedance growth rate and metal deposition amount of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0109] In some embodiments, the weight-average molecular weight of each B-block in the block copolymer is between 100,000 and 500,000. In some embodiments, the weight-average molecular weight of each B-block in the block copolymer is arbitrarily selected to be 100,000, 120,000, 150,000, 170,000, 200,000, 220,000, 250,000, 280,000, 300,000, 320,000, 350,000, 370,000, 400,000, 430,000, 450,000, 470,000, and 500,000.

[0110] BAB block copolymers in which the weight-average molecular weight of each B-block is within an appropriate range can improve the adhesion of the electrode plates, reduce the DC impedance growth rate and metal deposition amount of the battery, and ensure that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0111] One embodiment of this application provides a method for producing a BAB-type block copolymer, comprising the following steps: Production of B-block: B-block is produced by polymerizing at least one monomer shown in formula V, JPEG0007844677000006.jpg25170 Here, R'1, R'2, and R'3 are each independently hydrogen, fluorine, and C containing at least one fluorine atom. 1-3 One or more selected from alkyl groups, Production of A-block: A-block is produced by polymerizing at least one monomer shown in formula VI, or by ring-opening polymerization of a monomer shown in formula VII. JPEG0007844677000007.jpg39170 Here, R'4, R'5, and R'6 are each independently hydrogen, substituted, or unsubstituted C 1-5 Selected from alkyl groups, R′7 is one selected from carboxyl groups, ester groups, hydroxyl groups, amide groups, cyano groups, and substituted or unsubstituted aromatic groups. Production of BAB-type block copolymers: B-blocks and A-blocks are combined to produce BAB-type block copolymers.

[0112] This manufacturing method is advantageous because it uses inexpensive raw materials, reduces costs, minimizes environmental pollution, and improves the yield of adhesives. At the same time, the adhesive produced by this method effectively improves the adhesive strength of the electrode plates, reduces the DC impedance growth rate and metal deposition amount of the battery, and ensures that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0113] In some embodiments, the manufacturing step of the B-block is: The method includes reacting at least one monomer represented by formula V, a chain transfer agent, and a first initiator with a B-block having an azide group or an alkynyl group at the terminal end by reversible addition-cleavage chain transfer polymerization at a reaction temperature of 60-75°C for 4-6 hours.

[0114] In this specification, the term "azide group" refers to the -N3 group.

[0115] In this specification, the term "alkynyl group" refers to the -C≡CH group.

[0116] In this specification, the term “reversible addition-fragmentation chain transfer polymerization” (RAFT polymerization) is reversible deactivation radical polymerization, also known as “active” / controllable radical polymerization. The main principle of RAFT polymerization is to protect easily terminated radicals in a chain transfer manner by adding a RAFT reagent as a chain transfer reagent to radical polymerization, converting the majority of radicals in the polymerization reaction into dormant species radicals, so that dormant and active segments coexist during the reaction, constantly and rapidly switching between them by a dynamic reversible reaction, so that at any given time only a small number of polymer chains exist in the form of active chains, grow until the growth probability of each polymer segment becomes approximately equal, further expressing the characteristics of active polymerization.

[0117] In some embodiments, a schematic diagram of the synthesis route of B-block is shown in the following figure, where the chain transfer agent is trithiocarbonate, Z' is an active group containing an alkynyl or azide group at its terminus, and R is an alkyl group. B-blocks having an alkynyl or azide group at their terminus were produced by the following reaction. JPEG0007844677000008.jpg32106

[0118] By employing reversible addition-cleavage chain transfer polymerization, controllable polymerization can be achieved, and the molecular weight distribution of the product is narrow. Furthermore, through the above reaction, the B-block, having only alkynyl or azide groups at its terminals, is oriented efficiently and mildly to bond with the A-block, making it easy to produce a BAB-type block copolymer.

[0119] In some embodiments, the manufacturing step of block A is: The method involves polymerizing a monomer shown in formula VI with a second initiator at a reaction temperature of 80 to 95°C for 2.5 to 5 hours to obtain an A-block having either an alkynyl group or an azide group at both ends.

[0120] In some embodiments, the synthesis route for block A is shown below, and the monomer shown in formula I undergoes a polymerization reaction upon the action of the first initiator to produce block A. Since the terminal groups on both sides of the first initiator are halogen-substituted alkyl groups or trimethylsilylacetylene groups, the halogen or trimethylsilyl groups on both sides of block A are readily substituted, giving both ends of block A either an azide group or an alkynyl group (in the figure, B1 is a halogen-substituted alkyl group or trimethylsilylacetylene group, and B2 is an azide group or an alkynyl group). JPEG0007844677000009.jpg59157

[0121] By employing A-blocks produced by this manufacturing method, with both ends azidated or alkynylated, the A-blocks are linked to the B-blocks in an efficient and mild manner, facilitating the production of BAB-type block copolymers.

[0122] In some embodiments, the manufacturing step of block A is: The monomer shown in formula VII, an ion initiator, and water are polymerized at a reaction temperature of 60°C to 80°C for 6 to 8 hours to obtain a product having hydroxyl groups at both ends. The process involves functionalizing the hydroxyl group of the product to obtain an A-block having either an alkynyl group or an azide group at both ends.

[0123] In some embodiments, the synthesis route for block A is as follows: upon the action of a first initiator, the monomer shown in formula I undergoes a polymerization reaction to produce block A. Since the terminal groups on both sides of the first initiator are halogen-substituted alkyl groups or trimethylsilylacetylene groups, the halogen or trimethylsilyl groups on both sides of block A are readily substituted, giving both ends of block A either an azide group or an alkynyl group (in the figure, B1 is a halogen-substituted alkyl group or trimethylsilylacetylene group, and B2 is an azide group or an alkynyl group). JPEG0007844677000010.jpg59159

[0124] By employing A-blocks produced by this manufacturing method, with both ends azidated or alkynylated, the A-blocks are linked to the B-blocks in an efficient and mild manner, facilitating the production of BAB-type block copolymers.

[0125] In some embodiments, the production of BAB-type block copolymers is carried out by The process involves mixing an A-block, which has azide or alkynyl groups at both ends, with a B-block, which has alkynyl or azide groups at its ends, and performing a click reaction to produce a BAB-type block copolymer, wherein the terminal groups of the A-block and B-block are different.

[0126] In this specification, the term "click reaction" refers to a reaction in which an alkynyl group undergoes a cycloaddition reaction with an azide group, linking the A-block and the B-block. In some embodiments, the click reaction is carried out at room temperature and pressure in the presence of a Cu(I) catalyst.

[0127] In some embodiments, the terminal group of block A is an azide group, and the terminal group of block B is an alkynyl group.

[0128] In some embodiments, the terminal group of block A is an alkynyl group, and the terminal group of block B is an azide group.

[0129] The above manufacturing method has the advantages of high yield, harmless by-products, simple and mild reaction conditions, and readily available reaction materials, enabling controllable polymerization of block polymers and is advantageous in improving the yield rate of the product.

[0130] In some embodiments, the chain transfer agent is a RAFT chain transfer agent containing terminal alkynyl or azide groups. In some embodiments, the chain transfer agent is a trithiocarbonate containing terminal alkynyl or azide groups. In some embodiments, the structural formula of the chain transfer agent is selected from the following formulas: JPEG0007844677000011.jpg2888 JPEG0007844677000012.jpg2990 RAFT chain transfer agents containing terminal alkynyl or azide groups provide a basis for click reactions between B-blocks and A-blocks by simultaneously introducing alkynyl or azide groups to the terminals of B-blocks during B-block synthesis, thereby avoiding complex post-processing steps and improving reaction efficiency.

[0131] In some embodiments, the second initiator is a symmetrical bifunctional initiator. In some embodiments, the second initiator is 4-(chloromethyl)benzoyl peroxide. The symmetrical bifunctional initiator allows the A-block to have the same active functional group symmetrically on both sides, contributing to the simultaneous realization of azidation or alkyneation of the terminal groups on both sides of the A-block.

[0132] In some embodiments, the first initiator is one or two selected from azobisisobutyronitrile and azobisisoheptonitrile. Azo initiators are commonly used radical polymerization initiators that readily decompose to form radicals and readily induce radical polymerization.

[0133] In some embodiments, the BAB-type block copolymer may be used in a secondary battery, which optionally includes at least one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, and a potassium-ion battery.

[0134] [Positive plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, a conductive agent, and an adhesive, the adhesive being a BAB-type block copolymer produced by a BAB-type block copolymer or a BAB-type block copolymer produced by a manufacturing method in some embodiments.

[0135] The positive electrode plate has excellent flexibility and adhesive strength, as well as low film resistance.

[0136] In some embodiments, the adhesive force per unit length between the positive electrode film layer and the positive electrode current collector is 11 N / m or more. In some embodiments, the adhesive force per unit length between the positive electrode film layer and the positive electrode current collector is optionally 11 N / m, 11.5 N / m, 12 N / m, 12.5 N / m, 13 N / m, 13.5 N / m, 14 N / m, 14.5 N / m, 15 N / m, 15.5 N / m, 16 N / m, 16.5 N / m, 17 N / m, 17.5 N / m, 18 N / m, 18.5 N / m, 19 N / m, 19.5 N / m, and 20 N / m.

[0137] The adhesive strength per unit length between the positive electrode film layer and the positive electrode current collector can be tested using any means known in the art, for example, by referring to the national standard GB-T2790-1995 "Experimental Method for 180° Peel Strength of Adhesives". As an example, the positive electrode plate is cut into a test specimen of size 20 mm × 100 mm, and in preparation for use, the electrode plate is adhered to one side of the positive electrode film layer with double-sided tape, and compressed with a roll to completely adhere the double-sided tape and electrode plate. The other side of the double-sided tape is attached to the surface of stainless steel, and one end of the specimen is bent in the opposite direction, with a bending angle of 180°. A high-strength iron tensile machine is used for the test, one end of the stainless steel is fixed to the lower jig of the tensile machine, and the bent end of the specimen is fixed to the upper jig, and the angle of the specimen is adjusted to ensure that the upper and lower ends are in a vertical position, and the specimen is tensed at a speed of 50 mm / min until the positive electrode current collector is completely peeled off from the positive electrode film, and the displacement and force applied during this process are recorded. The adhesive force per unit length of the electrode plate is calculated by dividing the force when the forces are balanced by the width of the electrode plate in contact with the double-sided tape (the width direction of the electrode plate is perpendicular to the peeling direction). In this test, the width of the electrode plate is 20 mm.

[0138] The positive electrode film layer of the electrode plate and the positive electrode current collector have high adhesive strength, making it difficult for the positive electrode film layer to detach from the positive electrode current collector during use, thus contributing to improved battery cycle performance and safety.

[0139] In some embodiments, the positive electrode plate exhibits light transmission after undergoing three or more bending tests. In some embodiments, the positive electrode plate exhibits light transmission after undergoing four or more bending tests as described in 3.3, 3.5, 3.7, or four or more bending tests.

[0140] The flexibility test of the positive electrode plate can be performed using known methods. For example, after cold pressing, the positive electrode plate is cut into 20 x 100 mm test specimens, folded in half in the forward direction, flattened with a 2 kg roll, and then unfolded to check whether light transmission occurs through the gaps when viewed towards a light source. If light transmission does not occur, it is folded in half in the reverse direction, flattened with a 2 kg roll, and checked again when viewed towards a light source. This process is repeated until light transmission occurs through the gaps. The number of folds is recorded, the test is repeated three times, and the average value is taken to serve as reference data for the flexibility of the electrode plate.

[0141] The fact that the positive electrode plate can withstand three or more bending tests indicates that the electrode plate has good flexibility, is less prone to collapse during production, and is less prone to brittle fracture during use, contributing to an improved yield rate of batteries and enhanced battery safety performance.

[0142] In some embodiments, the film resistance of the positive electrode plate is 1.0 Ω or less.

[0143] Film resistance refers to the resistance of the positive electrode film layer on the electrode plate, and can be tested using any known means in this field. For example, it can be tested using a resistance measuring instrument.

[0144] The film resistance can be tested using a known method. For example, small discs with a diameter of 3 mm are cut to the left, center, and right of the electrode plate. Turn on the indicator lamp of the Yuan Neng Technology electrode plate resistance meter, place the probe of the film resistance meter in the appropriate position, click the "start" button, and read the reading after the reading stabilizes. Test two positions for each small disc, and finally calculate the average of the six measurements to obtain the film resistance of the electrode plate.

[0145] The fact that the electrode plate has low film resistance indicates that the dispersion of materials in the positive electrode film layer is uniform, and the positive electrode film layer having good electron transmission efficiency is advantageous for achieving optimal battery performance.

[0146] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0147] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may 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)).

[0148] In some embodiments, the positive electrode active material may 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 material from among lithium-containing phosphates with an olivine structure, lithium metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used individually or in combination of two or more. Here, examples of lithium metal oxides are 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, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (This can be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (This can be abbreviated as LiNi)0.5 Co 0.25 Mn 0.25 O2(NCM 211 (This can be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (This can be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This may be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (for example, LiNi 0.85 Co 0.15 Al 0.05 It may include, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

[0149] In some embodiments, the cathode film layer optionally further comprises a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0150] In some embodiments, the positive electrode plate may be manufactured by the following method: The components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is applied to a positive electrode current collector; and the positive electrode plate is obtained through processes such as drying and cold pressing.

[0151] [negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, the negative electrode film layer containing a negative electrode active material.

[0152] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0153] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may 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)).

[0154] In some embodiments, the negative electrode active material may be a negative 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 composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used individually or in combination of two or more.

[0155] In some embodiments, the negative electrode film layer optionally further comprises an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0156] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0157] In some embodiments, the negative electrode film layer optionally further comprises other auxiliary agents, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0158] In some embodiments, the negative electrode plate may be manufactured by the following method: The above components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is applied to a negative electrode current collector; and the negative electrode plate is obtained through processes such as drying and cold pressing.

[0159] [Electrolytes] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and it can be selected according to the requirements. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0160] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution comprises an electrolyte salt and a solvent.

[0161] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0162] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0163] In some embodiments, the electrolyte optionally further includes additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0164] [Separator] In some embodiments, the secondary battery further includes a separator. This application does not particularly limit the type of separator, and any well-known porous separator having good chemical and mechanical stability may be selected.

[0165] In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer thin film or a multilayer composite thin film, and is not particularly limited. If the separator is a multilayer composite thin film, the materials of each layer may be the same or different, and is not particularly limited.

[0166] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be manufactured as an electrode assembly by a winding process or a lamination process.

[0167] In some embodiments, the secondary battery may include an outer casing. This outer casing may be used to package the electrode assembly and electrolyte.

[0168] In some embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0169] [Secondary battery] This application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 2 shows a rectangular secondary battery 5 as an example. The secondary battery may be a sodium-ion battery, a magnesium-ion battery, or a potassium-ion battery.

[0170] In some embodiments, referring to Figure 3, the housing may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a housing cavity. The housing 51 has an opening that communicates with the housing cavity, and the cover plate 53 can close the housing cavity by covering the opening. The positive electrode plate, the negative electrode plate and the separator can form an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the housing cavity. The electrolyte permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art can select according to the actual specific requirements.

[0171] [Battery Module] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, the specific number which can be selected by those skilled in the art based on the application and capacity of the battery module.

[0172] Figure 4 shows an example of a battery module 4. Referring to Figure 4, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the vertical direction of the battery module 4. Of course, they may be arranged according to any other method. Furthermore, the multiple secondary batteries 5 may be fixed with fasteners.

[0173] Optionally, the battery module 4 may further include a housing having a housing space, and a plurality of secondary batteries 5 are housed in the housing space.

[0174] [Battery pack] In some embodiments, the battery modules may be further assembled into a battery pack, the number of battery modules included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0175] 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 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 being provided to cover the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged inside the battery box in any manner.

[0176] [Power consumption equipment] One embodiment of this application provides a power consumption device comprising at least one of a secondary battery, a battery module, or a battery pack of any embodiment.

[0177] The power consumption device includes at least one of the secondary battery, battery module, or battery pack as described in this application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0178] As a power consumption device, a secondary battery, battery module, or battery pack can be selected according to the user's needs.

[0179] Figure 7 shows an example of a power consumption device. This power consumption device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the power consumption device's demand for high power and high energy density of secondary batteries, a battery pack or battery module may be employed.

[0180] Other examples of such devices may include mobile phones, tablet computers, and laptop computers. These devices generally require lightweight designs and can utilize rechargeable batteries as their power source.

[0181] Examples The following describes embodiments of this application. The embodiments described below are illustrative and are for interpretive purposes only, and should not be considered as limitations thereon. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or in the product instructions shall be followed. Unless the manufacturer is specified for the reagents or instruments used, they are all common products that can be purchased commercially.

[0182] 1. Manufacturing method Example 1 1) Manufacturing of adhesives Production of B-block: Using a RAFT chain transfer agent (CTA-alkyne) as the chain transfer agent, an alkynyl-terminated polyvinylidene fluoride is produced by polymerization reaction. The structural formula of the RAFT chain transfer agent is shown below. JPEG0007844677000013.jpg2888

[0183] 4 g of vinylidene fluoride was weighed, and 500 ml of tetrahydrofuran was added to a four-necked flask. A large amount of nitrogen gas was introduced, and the stirring speed was gradually increased to 1200 rpm. 1% monomer mass of RAFT chain transfer agent (CTA-alkyne) and 0.1% monomer mass of azobisisobutyronitrile were added, and the temperature was raised to 75°C. After 6 hours of reaction, the reaction was stopped by cooling with liquid nitrogen, and the solution precipitated in a large excess of methanol. The polymer was collected by filtration and precipitated twice again from chloroform using methanol. The obtained product was vacuum-dried overnight at room temperature to remove all trace amounts of residual solvent, yielding polyvinylidene fluoride with alkynyl groups at the ends, i.e., B-block polymer.

[0184] The reaction process for producing B-block polymers is as follows: JPEG0007844677000014.jpg43160

[0185] Manufacturing of Block A: Using an azide as an initiator, a polymerization reaction is carried out to produce azide-terminated poly(acrylonitrile-butyl methacrylate-styrene), 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, acrylonitrile monomer, butyl methacrylate monomer, and styrene monomer were weighed in a molar ratio of 8:1:1 and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the obtained solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated poly(acrylonitrile-butyl methacrylate-styrene) and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain poly(acrylonitrile-butyl methacrylate-styrene), i.e., A-block polymer, which contains azides at both ends.

[0186] Production of BAB-type block copolymers: Poly(acrylonitrile-butyl methacrylate-styrene) having azide groups at both ends, polyvinylidene fluoride having alkynyl groups at the ends, and cuprous brominated were added in a molar ratio of 1:2.5:4 to a dry Schlenk tube. After degassing, 4 ml of anhydrous N,N-dimethylformamide (DMF) and 0.14 mmol of N,N,N',N,'N''-pentamethyldiethylenetriamine (PMDETA) were added. The reaction was stirred at 60°C for 3 days, and the reaction was stopped by exposure to air. The reaction mixture was filtered through a neutral aluminum oxide column to remove the copper catalyst, the solution was concentrated under reduced pressure, precipitated in a 20-fold excess mixed solvent (methanol to water in a 1:1 volume ratio), filtered to recover the product, and vacuum-dried to obtain a polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer with a weight-average molecular weight of 1.2 million, which was used as a battery adhesive.

[0187] 2) Manufacturing of positive electrode plates Lithium nickel cobalt manganese (NCM) material, conductive carbon black, the adhesive manufactured in Example 1, and N-methylpyrrolidone (NMP) were mixed uniformly by stirring in a weight ratio of 96.9:2.1:1:21 to obtain a positive electrode slurry, the solid content of which was 73%. The positive electrode slurry was then uniformly coated onto a positive electrode current collector, and subsequently dried, cold pressed, and slit to obtain a positive electrode plate.

[0188] 3) Manufacturing of the negative electrode plate A negative electrode slurry was produced by dissolving artificial graphite, an active material, carbon black, a conductive agent, styrene-butadiene rubber (SBR) as an adhesive, and sodium carboxymethylcellulose (CMC-Na) as a thickener in deionized water, a solvent, in a weight ratio of 96.2:0.8:0.8:1.2, and mixing them uniformly. The negative electrode slurry was then uniformly coated onto the copper foil of the negative electrode current collector in one or more passes, and a negative electrode plate was obtained through drying, cold pressing, and slitting.

[0189] 4) Separator A polypropylene film was used as the separator.

[0190] 5) Manufacturing of electrolyte In a glove box under an argon gas atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a volume ratio of 3 / 7. 12.5% ​​LiPF6 lithium salt was added and dissolved in the organic solvent, and the mixture was uniformly stirred to obtain the electrolyte of Example 1.

[0191] 6) Battery manufacturing A positive electrode plate, a separator, and a negative electrode plate were stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation, and then wound up to obtain a bare cell. Tabs were welded to the bare cell, the bare cell was placed in an aluminum case, baked at 80°C to remove moisture, and immediately injected electrolyte and sealed to obtain an uncharged battery. The uncharged battery was then subjected to a series of processes including standing, hot and cold pressing, chemical conversion, shaping, and capacity measurement to obtain the finished lithium-ion battery of Example 1.

[0192] Examples 2-5 The batteries of Examples 2 to 5 were similar to those of Example 1 in terms of manufacturing method, but only the weight-average molecular weight and mass content of Block A and Block B were adjusted, respectively. The weight-average molecular weight of the polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer was maintained at 1.2 million. The specific parameters are shown in Table 1.

[0193] Examples 6-9 The batteries of Examples 6 to 9 were manufactured using a method similar to that of Example 1. However, the weight-average molecular weight of the polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer was adjusted by adjusting the weight-average molecular weight and mass content of Block A and Block B, respectively. The specific parameters are shown in Table 1.

[0194] Example 10 The battery of Example 10 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with a polyacrylamide having azide groups at both ends. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0195] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, a fixed molar amount of acrylamide monomer was weighed and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated polyacrylamide and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water volume ratio of 1:1). Subsequently, the pale yellow product was vacuum-dried at 45°C to obtain a polyacrylamide containing azide compounds at both ends, i.e., an A-block polymer.

[0196] Example 11 The battery of Example 11 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with poly(acrylate-acrylamide-ethyl methacrylate) having azide groups at both ends. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0197] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, acrylic acid monomer, acrylamide monomer, and ethyl methacrylate monomer were weighed in a molar ratio of 8:1:1 and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the obtained solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated poly(acrylic acid-acrylamide-ethyl methacrylate) and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain poly(acrylamide-ethyl methacrylate), i.e., A-block polymer, which contains azides at both ends.

[0198] Example 12 The battery of Example 12 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with a poly(acrylonitrile-acrylamide-acrylic acid ester) having azide groups at both ends. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0199] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, acrylonitrile monomer, acrylamide monomer, and acrylic acid ester monomer were weighed in a molar ratio of 8:1:1 and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated poly(acrylonitrile-acrylamide-acrylic acid ester) and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain poly(acrylonitrile-acrylamide-acrylic acid ester), i.e., A-block polymer, which contains azides at both ends.

[0200] Example 13 The battery of Example 13 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with polystyrene having azide groups at both ends. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0201] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, a fixed molar amount of styrene monomer was weighed and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated polystyrene and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water volume ratio of 1:1). Subsequently, the pale yellow product was vacuum-dried at 45°C to obtain polystyrene containing azidides at both ends, i.e., A-block polymer.

[0202] Example 14 The battery of Example 14 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with polyethylene oxide having azide groups at both ends. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0203] Ethylene oxide monomer, water, and potassium hydrogen oxide (KOH) were added to a high-pressure stirring vessel in a molar ratio of 1:0.1:0.02. After introducing a large amount of nitrogen gas to remove air, the mixture was pressurized to 0.3 MPa, the stirring speed was gradually increased to 1000 rpm, and the temperature was raised to 80°C. After reacting for 6 hours, the pressure in the vessel decreased, and excess monomer was removed by short pressurization. The mixture was then purified to obtain polyethylene oxide. 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with nitrogen gas (N2) for 30 minutes. Subsequently, the polyethylene oxide was transferred to the reactor at room temperature. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomer was removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated polyethylene oxide and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain polyethylene oxide, i.e., A-block polymer, containing azidides at both ends.

[0204] Example 15 The battery of Example 15 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with polyvinyl alcohol. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0205] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, a fixed molar amount of vinyl acetate monomer was weighed and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the obtained solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum dried at 45°C to obtain a white product. Furthermore, the chlorine-terminated polyvinyl acetate obtained by the above reaction was dissolved in a mixed solvent (methanol to water volume ratio of 79.5:0.5), where the mass fraction of polyvinyl acetate was 20%, and at a temperature of 30°C, a 1.5% sodium hydrogen oxide solution was added, and the mixture was decomposed into alcohol for 2 hours. After thorough washing and filtration, chlorine-terminated polyvinyl alcohol was obtained. 3 mmol of chlorine-terminated polyvinyl alcohol and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain polyvinyl alcohol containing azidides at both ends, i.e., A-block polymer.

[0206] Example 16 The battery of Example 16 was similar to the battery manufacturing method of Example 1, but the A-block was replaced with poly(acrylonitrile-acrylic acetate), the specific parameters are as shown in Table 1, and the manufacturing method is as follows.

[0207] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, acrylonitrile monomer and acrylic acetate monomer were weighed in an 8:1 molar ratio and transferred to the reactor. The temperature inside the reactor was raised to 90°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 3 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product. 3 mmol of chlorine-terminated poly(acrylonitrile-acrylic acetate) and 60 mmol of sodium azidide (NaN3) were dissolved in 600 ml of N,N-dimethylformamide (DMF), stirred at 60°C, and left overnight. The polymer solution was concentrated and precipitated three times in a mixed solvent (methanol to water in a 1:1 volume ratio). The pale yellow product was then vacuum-dried at 45°C to obtain poly(acrylonitrile-acrylic acetate), i.e., A-block polymer, which contains azides at both ends.

[0208] Example 17 The battery of Example 17 was similar to the battery manufacturing method of Example 1, but the B-block was replaced with a polyvinyl fluoride block. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0209] 4 g of vinyl fluoride was weighed, and 500 ml of tetrahydrofuran was added to a four-necked flask. A large amount of nitrogen gas was introduced, and the stirring speed was gradually increased to 1200 rpm. 1% monomer mass of RAFT chain transfer agent (CTA-alkyne) and 0.1% monomer mass of azobisisobutyronitrile were added, and the temperature was raised to 75°C. After reacting for 6 hours, the reaction was stopped by cooling with liquid nitrogen, and the solution precipitated in a large excess of methanol. The polymer was collected by filtration and precipitated twice again from chloroform using methanol. The obtained product was vacuum-dried overnight at room temperature to remove all trace amounts of residual solvent, yielding polyvinyl fluoride with alkynyl groups at the ends, i.e., B-block polymer.

[0210] Example 18 The battery of Example 18 was similar to the battery manufacturing method of Example 1, but the B-block was replaced with a polytetrafluoroethylene block. The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0211] 4 g of tetrafluoroethylene was weighed, and 500 ml of tetrahydrofuran was added to a four-necked flask. A large amount of nitrogen gas was introduced, and the stirring speed was gradually increased to 1200 rpm. 1% monomer mass of RAFT chain transfer agent (CTA-alkyne) and 0.1% monomer mass of azobisisobutyronitrile were added, and the temperature was raised to 75°C. After reacting for 6 hours, the reaction was stopped by cooling with liquid nitrogen, and the solution precipitated in a large excess of methanol. The polymer was collected by filtration and precipitated twice again from chloroform using methanol. The obtained product was vacuum-dried overnight at room temperature to remove all trace amounts of residual solvent, yielding polytetrafluoroethylene with alkynyl groups at the ends, i.e., B-block polymer.

[0212] Comparative Example 1 The battery of Comparative Example 1 was manufactured using a method similar to that of Example 1, but the adhesive used was polyvinylidene fluoride, purchased from the Solvay Group, brand number 5130, and the specific parameters are shown in Table 1.

[0213] Comparative Example 2 The battery of Comparative Example 2 was similar to the battery manufacturing method of Comparative Example 1, but the adhesive was poly(acrylonitrile-butyl methacrylate-styrene), and the manufacturing method of poly(acrylonitrile-butyl methacrylate-styrene) is as follows.

[0214] 1% monomer by mass of 4-(chloromethyl)benzoyl peroxide was dissolved in 300 ml of anhydrous acetonitrile, and the solution was introduced into a high-pressure reactor and purged with N2 for 30 minutes. Then, at room temperature, acrylonitrile monomer, butyl methacrylate monomer, and styrene monomer were weighed in a molar ratio of 8:1:1 and added to 300 ml of anhydrous acetonitrile. The temperature inside the reactor was raised to 55°C, and the reaction mixture was stirred at a speed of 500 rpm for a further 12 hours. The reactor was cooled to room temperature with water, and unreacted monomers were removed by reducing the pressure. The solvent was removed by vacuum, and the resulting solid was washed multiple times with chloroform to remove initiator residue. Finally, the polymer was vacuum-dried at 45°C to obtain a white product, namely poly(acrylonitrile-butyl methacrylate-styrene).

[0215] Comparative Example 3 The battery of Comparative Example 3 was manufactured using a method similar to that of Comparative Example 1, but the adhesive was a blend of polyvinylidene fluoride and poly(acrylonitrile-butyl methacrylate-styrene). The specific parameters are shown in Table 1, and the manufacturing method is as follows.

[0216] Blending: Poly(acrylonitrile-butyl methacrylate-styrene) from Comparative Example 2 and polyvinylidene fluoride from Comparative Example 1 were blended in a molar ratio of 6:4 to obtain a blend adhesive of polyvinylidene fluoride and polyvinyl alcohol.

[0217] Comparative Example 4 The battery of Comparative Example 4 was manufactured using a method similar to that of Comparative Example 3, but the adhesive was a blend of polyvinylidene fluoride and polyacrylamide, and the specific parameters are shown in Table 1.

[0218] Comparative Example 5 The battery of Comparative Example 5 was manufactured using a method similar to that of Comparative Example 3, but the adhesive was a blend of polyvinylidene fluoride and poly(acrylate-acrylamide-ethyl methacrylate), and the specific parameters are shown in Table 1.

[0219] Comparative Example 6 The battery of Comparative Example 6 was manufactured using a method similar to that of Comparative Example 3, but the adhesive was a blend of polyvinylidene fluoride and polyvinyl alcohol, and the specific parameters are shown in Table 1.

[0220] 2. Performance Test 1. Polymer property testing 1) Weight-average molecular weight testing method A Waters 2695 isocratic-time HPLC gel chromatograph (with a differential refractive index detector 2141) was used. A 3.0% polystyrene solution sample was used as a reference, and an appropriate column (oil-based: Styragel time T5DMF 7.8*300mm + Styragel time T4) was selected. A 3.0% polymer gel solution was prepared in purified N-methylpyrrolidone (NMP) solvent, and the prepared solution was allowed to stand for 1 day to prepare for use. When testing, tetrahydrofuran was first drawn up with a syringe, washed, and repeated several times. Then 5 ml of the experimental solution was drawn up, the air in the syringe was removed, the needle tip was cleaned, and finally, the sample solution was slowly injected into the sample inlet. Data was acquired after the index stabilized.

[0221] 2. Plate performance test 1) Film resistance test Small discs with a diameter of 3 mm were cut to the left, center, and right of the electrode plate. Turn on the indicator lamp of the Yuan Neng Technology electrode plate resistance meter, place the probe of the film resistance meter in the appropriate position, click the "Start" button, and read the reading after the reading stabilizes. Two positions were tested for each small disc, and finally the average of the six measurements was calculated to determine the film resistance of the electrode plate.

[0222] 2) Adhesion strength test The positive electrode plate was cut into a 20mm x 100mm test specimen. In preparation for use, the electrode plate was adhered to one side of the positive electrode film layer with double-sided tape, and compressed with a roll to ensure complete adhesion between the double-sided tape and the electrode plate. The other side of the double-sided tape was attached to the surface of stainless steel, and one end of the specimen was bent in the opposite direction at a bending angle of 180°. A high-strength iron tensile machine was used for the test. One end of the stainless steel was fixed to a jig at the bottom of the machine, and the bent end of the specimen was fixed to a jig at the top. The angle of the specimen was adjusted to ensure that the upper and lower ends were in a vertical position. The specimen was then pulled at a speed of 50mm / min until the current collector was completely detached from the positive electrode film, and the displacement and force during this process were recorded. The adhesive force per unit length of the electrode plate was calculated by dividing the force when the forces were balanced by the width of the electrode plate in contact with the double-sided tape (the width direction of the electrode plate is perpendicular to the detachment direction). The width of the electrode plate in this test was 20mm.

[0223] 3) Flexibility test After cold pressing, the positive electrode plate was cut into 20 x 100 mm test samples. These were folded in half in the forward direction, flattened with a 2 kg roll, and then unfolded. The sample was then inspected to see if light transmission occurred through the gap when viewed against a light source. If no light transmission occurred, the sample was folded in half in the reverse direction, flattened with a 2 kg roll, and inspected again against a light source. This process was repeated until light transmission occurred through the gap. The number of folds was recorded, and the test was repeated three times. The average value was taken and used as reference data for the flexibility of the electrode plate.

[0224] 3. Battery performance test 1) DC impedance test of battery The DC impedance test procedure for the battery is as follows: At 25°C, the battery was charged to 4.3V with a constant current of 1 / 3C, then further charged with a constant voltage of 4.3V until the current was 0.05C, and left for 5 minutes, after which the voltage V1 was recorded. Then, the battery was discharged at 1 / 3C for 30s, and the voltage V2 was recorded. The internal resistance DCR1 of the battery after the first cycle was obtained by (V2-V1) / (1 / 3C). The above steps were repeated for the same battery, and the internal resistance DCRn of the battery after the nth cycle (n=1, 2, 3...100) was recorded. The values ​​of the 100 points DCR1, DCR2, DCR3...DCR100 were used as the vertical coordinate, and the corresponding number of cycles was used as the horizontal coordinate to obtain a curve diagram of the battery discharge DCR and the number of cycles.

[0225] In the test process, the first cycle corresponds to n=1, the second cycle to n=2, ... the 100th cycle to n=100. The internal resistance increase ratio of the battery in Example 1 in Table 2 is (DCRn - DCR1) / DCR1 * 100%, and the test process for the comparative example and other examples is the same as above. The data in Table 2 are the data measured after 100 cycles under the above test conditions.

[0226] 2) Battery cycle capacity retention rate test The battery capacity retention rate test process was as follows: At 25°C, a manufactured battery was charged to 4.3V with a constant current of 1 / 3C, then charged again with a constant voltage of 4.3V until the current was 0.05C, left for 5 minutes, and then discharged to 2.8V with 1 / 3C. The resulting capacity was defined as the initial capacity C0. The above steps were repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle was recorded. The post-cycle battery capacity retention rate Pn = Cn / C0 × 100% was used for each cycle. The values ​​of 500 points, P1, P2...P500, were used as the vertical coordinate, and the corresponding cycle count was used as the horizontal coordinate to obtain a curve diagram of the battery capacity retention rate and the number of cycles. In this test process, the first cycle corresponds to n=1, the second cycle to n=2, ... the 500th cycle to n=500. The battery capacity retention rate data corresponding to the examples or comparative examples in Table 2 are data measured after 500 cycles under the above test conditions, i.e., the P500 value. The test procedures for the comparative examples and other examples are the same as described above.

[0227] 3) Metal deposition test At room temperature, the fabricated lithium-ion battery underwent its first charge and discharge with a current of 0.5C (i.e., the current value that completely discharges the theoretical capacity within 2 hours). The charge was constant current constant voltage charge, with a stop voltage of 4.2V, a cutoff current of 0.05C, and a discharge stop voltage of 2.8V. After leaving the battery for 24 hours, it was charged to 4.2V with a constant current constant voltage of 0.5C, and then the fully charged battery was discharged with a current of 1C, with a discharge stop voltage of 2.8V in both cases. The battery core was disassembled, the negative electrode plate was removed, and the amount of metallic Co and Mn deposited was tested using the inductively coupled plasma (ICP) method.

[0228] 4) 45°C Volume Retention Rate Test Charge the battery to 4.2V with a constant current of 1C, then charge it again with a constant voltage of 4.2V until the current drops to 0.05C, leave it for 10 minutes, then discharge it with a constant current of 1C until the cutoff voltage is 2.8V, and record the capacity before storage (CAP1). Charge the lithium-ion battery again with a constant current of 1C until the cutoff voltage is 4.2V, then charge it again with a constant voltage of 4.2V until the current drops to 0.05C, leave the lithium-ion battery in a 45°C oven for 120 days, then remove it and discharge it with a constant current of 1C until the current drops to 2.8V, and record the capacity after storage (CAP2). Calculate the storage capacity retention rate of the lithium-ion secondary battery according to the following formula: The storage capacity retention rate (%) of a lithium-ion secondary battery = CAP2 / CAP1 × 100%.

[0229] III. Analysis of Test Results for Each Example and Comparative Example Batteries for each example and comparative example were manufactured according to the method described above, and each performance parameter was measured. The results are shown in Tables 1 and 2 below.

[0230] Table 1: Manufacturing parameters and weight-average molecular weight test results for examples and comparative examples. JPEG0007844677000015.jpg248154 JPEG0007844677000016.jpg144161

[0231] Table 2 Performance test results of the examples and comparative examples JPEG0007844677000017.jpg251161 JPEG0007844677000018.jpg140160

[0232] As can be seen from the above results, the adhesives in Examples 1 to 18 were BAB-type block copolymers, comprising A-block and B-block, where B-block contained at least one structural unit derived from vinylidene fluoride, vinyl fluoride, or tetrafluoroethylene, and A-block contained at least one structural unit derived from acrylonitrile, butyl methacrylate, styrene, acrylamide, acrylic acid, ethyl methacrylate, acrylic acid ester, ethylene oxide, vinyl alcohol, or acrylic acetate. As can be seen from the comparison between Examples 1-18 and Comparative Example 1, compared to using pure vinylidene fluoride polymer as an adhesive, polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-polyacrylamide-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-poly(acrylic acid-acrylamide-ethyl methacrylate)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-poly(acrylonitrile-acrylamide-acrylic acid ester)-polyvinylidene fluoride block copolymer, polyvinylidene fluoride-polystyrene-polyvinylidene fluoride block copolymer, and polyvinylidene fluoride-polyethylene oxa By using polyvinylidene fluoride block copolymers, polyvinylidene fluoride-polyvinyl alcohol-polyvinylidene fluoride block copolymers, polyvinylidene fluoride-poly(acrylonitrile-acrylic acetate)-polyvinylidene fluoride block copolymers, polyvinyl fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinyl fluoride block copolymers, and polytetrafluoroethylene-poly(acrylonitrile-butyl methacrylate-styrene)-polytetrafluoroethylene BAB-type block copolymers as adhesives, the adhesive strength of the electrode plates can be effectively improved, reducing the DC impedance growth rate and metal deposition amount of the battery, achieving both low film resistance and excellent flexibility in the electrode plates, and enabling the battery to achieve both high cycle capacity retention and 45°C capacity retention.

[0233] The adhesives in Examples 1-18 are BAB-type block copolymers, comprising A-blocks and B-blocks, where B-blocks contain a fluorine-containing polymer and A-blocks contain a non-fluorine-containing polymer. The adhesives in Comparative Examples 3-6 are blends of fluorine-containing polymers and non-fluorine-containing polymers. As can be seen from a comparison between Examples 1-18 and Comparative Examples 3-6, compared to using a blend of fluorine-containing polymers and non-fluorine-containing polymers as an adhesive, the BAB-type block copolymer effectively improves the adhesion and flexibility of the electrode plates, reduces the DC impedance growth rate and metal deposition amount of the battery, ensures low film resistance of the electrode plates, and enables the battery to achieve both high cycle capacity retention and 45°C capacity retention.

[0234] The adhesives in Examples 10-12 were BAB-type block copolymers, comprising A-blocks and B-blocks, where B-blocks contained structural units derived from vinylidene fluoride, and A-blocks contained at least structural units derived from acrylamide. As can be seen from a comparison between Examples 10-12 and Comparative Example 1, compared to using a pure polyvinylidene fluoride polymer as an adhesive, the above BAB-type block copolymers can effectively improve the adhesive strength and flexibility of the electrode plates, reduce the film resistance of the electrode plates, increase the battery's cycle capacity retention rate and 45°C capacity retention rate, and reduce the battery's DC impedance growth rate and metal deposition.

[0235] The adhesives in Examples 1-5, 12, and 16 were BAB-type block copolymers, comprising A-blocks and B-blocks. The B-blocks contained structural units derived from vinylidene fluoride, while the A-blocks contained at least structural units derived from acrylonitrile and structural units derived from butyl methacrylate, acrylic acid esters, or acrylic acetate esters. As can be seen from a comparison between Examples 1-5, 12, and 16 and Comparative Example 1, using the above BAB-type block copolymer as an adhesive effectively improves the adhesive strength and flexibility of the electrode plates, reduces the film resistance of the electrode plates, reduces the DC impedance growth rate and metal deposition amount of the battery, and ensures that the battery achieves both a high cycle capacity retention rate and a 45°C capacity retention rate.

[0236] The adhesive of Example 4 is a BAB-type block copolymer, comprising A-block and B-block, where B-block contains structural units derived from vinylidene fluoride, and A-block contains structural units derived from acrylonitrile, structural units derived from butyl methacrylate, and structural units derived from styrene. As can be seen from the comparison between Example 4 and Examples 10-16, using polyvinylidene fluoride-poly(acrylonitrile-butyl methacrylate-styrene)-polyvinylidene fluoride BAB-type block copolymer as an adhesive significantly improves the adhesive strength and flexibility of the electrode plates, as well as further improves the battery's cycle capacity retention rate and 45°C capacity retention rate.

[0237] The adhesive of Example 12 is a BAB-type block copolymer, comprising A-block and B-block. The B-block contains structural units derived from vinylidene fluoride, and the A-block contains structural units derived from acrylonitrile, acrylamide, and acrylic acid ester. As can be seen from a comparison of Example 12 with Examples 4, 10-11, and 13-16, using a polyvinylidene fluoride-poly(acrylonitrile-acrylamide-acrylic acid ester)-polyvinylidene fluoride block copolymer (BAB-type block copolymer) as an adhesive can significantly reduce the amount of metal deposited in the battery.

[0238] As can be seen from the comparison between Examples 1-5 and Comparative Example 1, using a BAB-type block copolymer with a mass content of 40%-60% A-block as an adhesive improves the adhesive strength and flexibility of the electrode plates, reduces the film resistance of the electrode plates, increases the battery's cycle capacity retention rate, and reduces the battery's DC impedance growth rate and metal deposition compared to using a pure polyvinylidene fluoride polymer as an adhesive. As can be seen from the comparison between Examples 1-5 and Comparative Example 3, using a BAB-type block copolymer with a mass content of 40%-60% A-block as an adhesive improves the adhesive strength and flexibility of the electrode plates, reduces the battery's DC impedance growth rate, and ensures that the electrode plates have low film resistance, low metal deposition, and high cycle capacity retention rate and 45°C capacity retention rate.

[0239] As can be seen from the comparison between Examples 1, 6-9 and Comparative Example 1, using a BAB-type block copolymer with a weight-average molecular weight of 400,000 to 2,000,000 as the adhesive improves the adhesion strength of the electrode plates, reduces the DC impedance growth rate of the battery, and ensures that the electrode plates have both low film resistance and excellent flexibility, thereby guaranteeing that the battery has both low metal deposition and a high cycle capacity retention rate. As can be seen from the comparison between Examples 1, 6-9 and Comparative Example 3, using a BAB-type block copolymer with a weight-average molecular weight of 400,000 to 2,000,000 as the adhesive improves the adhesion strength and flexibility of the electrode plates, reduces the DC impedance growth rate of the battery, and ensures that the electrode plates have low film resistance, thereby guaranteeing that the battery has both low metal deposition and a high cycle capacity retention rate and a 45°C capacity retention rate.

[0240] As can be seen from the comparison between Examples 1-5 and Comparative Example 1, using a BAB-type block copolymer, in which the weight-average molecular weight of fluorine-containing block A-block is 200,000 to 1,100,000 and the weight-average molecular weight of block B-block is 100,000 to 500,000, as an adhesive improves the adhesive strength and flexibility of the electrode plates, reduces the film resistance of the electrode plates, increases the battery's cycle capacity retention rate and 45°C capacity retention rate, and reduces the battery's DC impedance growth rate and metal deposition amount.

[0241] As can be seen from the comparison between Examples 1-5 and Comparative Example 3, using a BAB-type block copolymer as an adhesive, in which the weight-average molecular weight of fluorine-containing block A-block is 200,000 to 1,100,000 and the weight-average molecular weight of block B-block is 100,000 to 500,000, improves the adhesive strength and flexibility of the electrode plates, reduces the DC impedance growth rate of the battery, and simultaneously achieves low film resistance on the electrode plates, ensuring that the battery has low metal deposition, high cycle capacity retention rate and 45°C capacity retention rate.

[0242] It should be noted that this application is not limited to the above embodiments. The above embodiments are examples, and embodiments that have substantially the same configuration as the technical idea within the scope of the technical solution of this application and exhibit the same effects are all included within the technical scope of this application. In addition, within the scope not departing from the spirit of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other forms constructed by combining some components in the embodiments are also included within the scope of this application. Preferred embodiments of the present invention are as follows: [1] A BAB type block copolymer, wherein the B-block contains the structural unit shown in formula I, and the A-block contains one or more of the structural units shown in formula II and the structural units shown in formula III. JPEG0007844677000019.jpg60170 Here, R 1 、R 2 、R 3 Each of these independently contains hydrogen, fluorine, and at least one fluorine atom. 1-3 One or more selected from alkyl groups, R 4 、R 5 、R 6 These are, independently, hydrogen, substituted or unsubstituted C 1-5 Selected from alkyl groups, R 7 A BAB-type block copolymer characterized in that it is selected from carboxyl groups, ester groups, hydroxyl groups, amide groups, cyano groups, and substituted or unsubstituted aromatic groups. [2] The A-block is R 7 The BAB-type block copolymer according to [1], characterized in that it contains a structural unit shown in formula II, in which is an amide group. [3] The A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The BAB-type block copolymer according to [1], characterized in that it contains a structural unit shown in formula II, which is an ester group. [4] The A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The structural unit shown in formula II, in which R is an ester group, 7 The BAB-type block copolymer according to [1], characterized in that it contains a structural unit shown in formula II, which is a substituted or unsubstituted aromatic group. [5] The A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The structural unit shown in formula II, in which R is an amide group, 7 The BAB-type block copolymer according to [1], characterized in that it contains a structural unit shown in formula II, which is an ester group. [6] The BAB-type block copolymer according to [1], characterized in that the mass content of the A-block is 40% to 60% based on the total mass of the block copolymer. [7] The BAB-type block copolymer according to any one of the above claims [1] to [6], characterized in that the weight-average molecular weight of the block copolymer is 400,000 to 2,000,000. [8] The BAB-type block copolymer according to any one of the above [1] to [6], characterized in that the weight-average molecular weight of the A-block in the block copolymer is 200,000 to 1,100,000. [9] The BAB-type block copolymer according to any one of the above claims [1] to [6], characterized in that the weight-average molecular weight of each B-block in the block copolymer is 100,000 to 500,000.

[10] The BAB-type block copolymer according to any one of [1] to [6], characterized in that the structural unit shown in formula I is derived from the group consisting of vinylidene fluoride, tetrafluoroethylene, vinyl fluoride, hexafluoropropene and combinations thereof.

[11] The BAB-type block copolymer according to [1], characterized in that the structural unit shown in formula II is derived from the group consisting of acrylonitrile, crotononitrile, styrene, vinyl alcohol, acrylamide, ethyl acrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid, ethacrylic acid, methacrylamide, N-methacrylamide, N-methylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, Nt-butylacrylamide, Nt-butyl(meth)acrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, acrylic acid, vinylbenzoic acid, acrylic acetate, acrylic acid ester, and combinations thereof.

[12] A method for producing a BAB-type block copolymer, A B-block is produced by polymerizing at least one monomer shown in formula V, JPEG0007844677000020.jpg25170 Here, R' 1 、R′ 2 、R′ 3 Each of these independently contains hydrogen, fluorine, and at least one fluorine atom.1-3 A manufacturing step of a B-block which is one or more selected from alkyl groups, A block is produced by polymerizing at least one monomer shown in formula VI, or by ring-opening polymerization of a monomer shown in formula VII. JPEG0007844677000021.jpg39170 Here, R' 4 、R′ 5 、R′ 6 These are, independently, hydrogen, substituted or unsubstituted C 1-5 Selected from alkyl groups, R′ 7 The manufacturing step of block A is one selected from a carboxyl group, ester group, hydroxyl group, amide group, cyano group, or substituted or unsubstituted aromatic group, A method for producing a BAB-type block copolymer, characterized by comprising the steps of: combining the B-block and the A-block to produce a BAB-type block copolymer; and producing a BAB-type block copolymer.

[13] The manufacturing step of the B-block is: The method for producing a B-block having an azide group or an alkynyl group at the end, characterized by reacting at least one monomer represented by formula V, a chain transfer agent, and a first initiator with a first initiator by reversible addition-cleavage chain transfer polymerization at a reaction temperature of 60 to 75°C for 4 to 6 hours.

[14] The manufacturing step of the A-block is: The method for producing the A-block according to

[12] or

[13] , characterized by comprising polymerizing at least one monomer represented by formula VI and a second initiator at a reaction temperature of 80 to 95°C for 2.5 to 5 hours to obtain the A-block having an alkynyl group or an azide group at both ends.

[15] The manufacturing step of the A-block is: The monomer shown in formula VII, an ion initiator, and water are polymerized at a reaction temperature of 60°C to 80°C for 6 to 8 hours to obtain a product having hydroxyl groups at both ends. The method for producing the product according to

[12] or

[13] , characterized by comprising a functionalization reaction of the hydroxyl group of the product to obtain the A-block having an alkynyl group or an azide group at both ends.

[16] The production of the BAB-type block copolymer is The manufacturing method according to any one of the above

[12] to

[15] , comprising mixing the A-block, which has an azide group or an alkynyl group at both ends, with the B-block, which has an alkynyl group or an azide group at its end, and performing a click reaction to produce a BAB-type block copolymer, wherein the terminal groups of the A-block and the B-block are different.

[17] The manufacturing method according to

[12] or

[13] , characterized in that the chain transfer agent is a RAFT chain transfer agent containing a terminal alkynyl group or an azide group.

[18] The manufacturing method according to

[12] or

[13] , characterized in that the second initiator is a symmetrical bifunctional initiator.

[19] The manufacturing method according to

[12] or

[13] , characterized in that the first initiator is one or two selected from azobisisobutyronitrile and azobisisoheptonitrile.

[20] Application of the BAB-type block copolymer described in any one of the above items [1] to

[11] in a secondary battery.

[21] A positive electrode plate comprising a positive electrode current collector and a positive electrode film layer installed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, a conductive agent, and an adhesive, and the adhesive is a BAB-type block copolymer described in any one of the above items [1] to

[11] or a BAB-type block copolymer manufactured by the manufacturing method described in any one of the above items

[12] to

[19] .

[22] The positive electrode plate according to

[21] , characterized in that the adhesive force per unit length between the positive electrode film layer and the positive electrode current collector is 11 N / m or more.

[23] The positive electrode plate according to

[21] , characterized in that a light transmission phenomenon occurs in the positive electrode plate after undergoing three or more bending tests.

[24] The positive electrode plate according to

[21] , characterized in that the film resistance of the positive electrode plate is 1.0 Ω or less.

[25] A secondary battery comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a separator, a negative electrode plate, and a positive electrode plate as described in any one of

[21] to

[24] .

[26] The secondary battery according to

[25] , characterized in that 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.

[27] A battery module characterized by including the secondary battery described in

[25] or

[26] above.

[28] A battery pack comprising a secondary battery as described in

[25] or

[26] and a battery module as described in

[27] .

[29] A power consumption device characterized by including at least one selected from the secondary battery described in

[25] or

[26] , the battery module described in

[27] , or the battery pack described in

[28] .

Explanation of Symbols

[0243] 1 Battery pack, 2 Upper housing, 3 Lower housing, 4 Battery module, 5 Secondary battery, 51 Case, 52 Electrode assembly, 53 Cover plate.

Claims

1. A positive electrode plate comprising a positive electrode current collector and a positive electrode film layer installed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, a conductive agent, and an adhesive, the adhesive comprises a BAB type block copolymer, the B-blocks comprising structural units shown in formula I, and the A-blocks comprising one or more structural units shown in formula II and formula III. Here, R 1 、R 2 、R 3 are each independently one or more selected from hydrogen, fluorine, and C 1-3 alkyl groups containing at least one fluorine atom, R 4 、R 5 、R 6 are each independently one or more selected from hydrogen, substituted or unsubstituted C 1-5 alkyl groups, and R 7 is one or more selected from a carboxyl group, an ester group, a hydroxyl group, an amide group, a cyano group, and a substituted or unsubstituted aromatic group. The positive electrode plate is characterized by this.

2. The aforementioned A-block is R 7 The positive electrode plate according to claim 1, characterized in that it contains a structural unit shown in formula II, in which is an amide group.

3. The aforementioned A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The positive electrode plate according to claim 1, characterized in that it contains a structural unit shown in formula II, which is an ester group.

4. The aforementioned A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The structural unit shown in formula II, in which R is an ester group, 7 The positive electrode plate according to claim 1, characterized in that it contains a structural unit shown in formula II, which is a substituted or unsubstituted aromatic group.

5. The aforementioned A-block is R 7 The structural unit shown in formula II is a cyano group, and R 7 The structural unit shown in formula II is an amide group, and R 7 The positive electrode plate according to claim 1, characterized in that it contains a structural unit shown in formula II, which is an ester group.

6. The positive electrode plate according to claim 1, characterized in that the mass content of the A-block is 40% to 60% based on the total mass of the block copolymer.

7. The positive electrode plate according to claim 1, characterized in that the weight-average molecular weight of the block copolymer is 400,000 to 2,000,000.

8. The positive electrode plate according to claim 1, characterized in that the weight-average molecular weight of the A-block in the block copolymer is 200,000 to 1,100,000.

9. The positive electrode plate according to claim 1, characterized in that the weight-average molecular weight of each B-block in the block copolymer is 100,000 to 500,000.

10. The positive electrode plate according to claim 1, characterized in that the structural unit shown in formula I is derived from one or more of the group consisting of vinylidene fluoride, tetrafluoroethylene, vinyl fluoride, and hexafluoropropene.

11. The positive electrode plate according to claim 1, characterized in that the structural unit shown in formula II is derived from one or more of the group consisting of acrylonitrile, crotononitrile, styrene, vinyl alcohol, acrylamide, ethyl acrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid, ethacrylic acid, methacrylamide, N-methacrylamide, N-methylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-t-butylacrylamide, N-t-butyl(meth)acrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, acrylic acid, vinylbenzoic acid, acrylic acetate, and acrylic acid ester.

12. A method for manufacturing a positive electrode plate, A B-block is produced by polymerizing at least one monomer shown in formula V. Here, R' 1 , R' 2 , R' 3 Each of these independently contains hydrogen, fluorine, and at least one fluorine atom. 1-3 A manufacturing step of a B-block which is one or more selected from alkyl groups, A block is produced by polymerizing at least one monomer shown in formula VI, or by ring-opening polymerization of a monomer shown in formula VII. Here, R' 4 , R' 5 , R' 6 These are, independently, hydrogen, substituted or unsubstituted C 1-5 One or more selected alkyl groups, R' 7 The manufacturing step of block A is one or more selected from carboxyl groups, ester groups, hydroxyl groups, amide groups, cyano groups, and substituted or unsubstituted aromatic groups, A step for producing a BAB-type block copolymer, comprising combining the B-block and the A-block to produce a BAB-type block copolymer, A positive electrode plate manufacturing step, in which a positive electrode plate is manufactured using the BAB-type block copolymer as an adhesive, A method for manufacturing a positive electrode plate, characterized by including the following:

13. The manufacturing step of the B-block is as follows: The production method according to claim 12, characterized by comprising reacting at least one monomer represented by formula V, a chain transfer agent, and a first initiator with a B-block having an azide group or an alkynyl group at the end by reversible addition-cleavage chain transfer polymerization at a reaction temperature of 60 to 75°C for 4 to 6 hours.

14. The manufacturing step of block A is as follows: The production method according to claim 12, characterized in that it includes polymerizing at least one monomer represented by formula VI and a second initiator at a reaction temperature of 80 to 95°C for 2.5 to 5 hours to obtain the A-block having an alkynyl group or an azide group at both ends.

15. The manufacturing step of block A is as follows: The monomer shown in formula VII, an ion initiator, and water are polymerized at a reaction temperature of 60°C to 80°C for 6 to 8 hours to obtain a product having hydroxyl groups at both ends. The method for producing the product according to claim 12, characterized by comprising a functionalization reaction of the hydroxyl group of the product to obtain the A-block having either an alkynyl group or an azide group at both ends.

16. The production of the aforementioned BAB-type block copolymer is as follows: The manufacturing method according to claim 12, comprising mixing the A-block, which has an azide group or an alkynyl group at both ends, with the B-block, which has an alkynyl group or an azide group at its end, and performing a click reaction to produce a BAB-type block copolymer, wherein the terminal groups of the A-block and the B-block are different.

17. The manufacturing method according to claim 13, characterized in that the chain transfer agent is a RAFT chain transfer agent containing a terminal alkynyl group or an azide group.

18. The manufacturing method according to claim 14, characterized in that the second initiator is a symmetrical bifunctional initiator.

19. The manufacturing method according to claim 13, characterized in that the first initiator is one or two selected from azobisisobutyronitrile and azobisisoheptonitrile.

20. The positive electrode plate according to claim 1, characterized in that the adhesive force per unit length between the positive electrode film layer and the positive electrode current collector is 11 N / m or more.

21. The positive electrode plate according to claim 1, characterized in that, after undergoing three or more bending tests, a light transmission phenomenon occurs in the positive electrode plate.

22. The positive electrode plate according to claim 1, characterized in that the film resistance of the positive electrode plate is 1.0 Ω or less.

23. A secondary battery comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a separator, a negative electrode plate, and a positive electrode plate as described in claim 1.

24. The secondary battery according to claim 23, characterized in that 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.

25. A battery module characterized by including a secondary battery as described in claim 23.

26. A battery pack characterized by including the secondary battery described in claim 23.

27. A power consumption device characterized by including a secondary battery as described in claim 23.

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