Battery, positive electrode slurry, dispersing adhesive and preparation method

Abstract

The invention discloses a battery, a positive electrode slurry, a dispersion adhesive and a preparation method thereof, and electric equipment, the battery comprises a positive electrode plate, the positive electrode plate comprises a current collector and a positive electrode material layer arranged on at least one side of the current collector, the positive electrode material layer comprises a positive electrode active material and the dispersion adhesive, the dispersion adhesive comprises a cyano polymer, and the cyano polymer is arranged on the positive electrode active material. The cyano polymer comprises a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene and a structural unit C derived from substituted olefin; wherein the substituted olefin comprises at least one substituent group R ', and R' comprises any one of alkyl, aryl, carboxyl, ester group, carboxylate, acylamino, hydroxyl, alkoxy, amido or ammonium salt. The dispersion adhesive can provide dispersion and adhesion effects at the same time, the dispersibility of the positive electrode slurry is improved, and the uniformity and flexibility of the positive electrode plate are improved, so that the battery has relatively high capacity and stability.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to batteries, cathode slurries, dispersants and binders, their preparation methods, and electrical equipment. Background Technology

[0002] Lithium-ion batteries have high energy density and are widely used in wireless communication, transportation, aerospace, and other fields. In the manufacturing process of lithium-ion batteries, the positive electrode is typically made by coating a positive electrode slurry onto a current collector and then drying it. Therefore, the properties of the positive electrode slurry affect the electrochemical performance and stability of the positive electrode, and consequently, the performance of the battery.

[0003] Insufficient dispersion of the positive electrode slurry reduces the uniformity of the positive electrode sheet, leading to battery capacity loss. Excessive coating thickness and compaction density of the positive electrode slurry result in greater brittleness, reduced stability, and increased susceptibility to cracking. The above statements are for informational purposes only and do not necessarily constitute prior art. Summary of the Invention

[0004] The main technical problem solved by this application is to provide a battery, a positive electrode slurry, a dispersing binder and its preparation method, and an electrical device, which can improve the dispersibility of the positive electrode slurry, improve the uniformity and flexibility of the positive electrode sheet, and enable the battery to have a high capacity retention rate and stability.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide a battery, the battery including a positive electrode sheet, the positive electrode sheet including a current collector and a positive electrode material layer disposed on at least one side of the current collector, the positive electrode material layer including a positive electrode active material and a dispersing binder, the dispersing binder including a cyano polymer, the cyano polymer including a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene and a structural unit C derived from a substituted olefin; wherein, the substituted olefin includes at least one substituent group R', R' including at least one of alkyl with 1-18 carbon atoms, aryl, carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino or ammonium salt with 6-18 carbon atoms.

[0006] Dispersants and binders can provide both dispersion and adhesion, improving the dispersibility of the positive electrode slurry and enhancing the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity retention and stability.

[0007] In one embodiment, in the cyanopolymer, the molar percentage of structural unit A is 10%-30%, the molar percentage of structural unit B is 60%-80%, and the molar percentage of structural unit C is 10%-20%. When the molar percentages of each structural unit in the cyanopolymer are within the above ranges, good adsorption can be achieved between the dispersant / binder and the cathode material particles, and between the dispersant / binder and the dispersion medium, resulting in better dispersion; better adhesion performance; and better flexibility of the polymer molecular chains.

[0008] In one embodiment, the cyano polymer further includes at least one substituent G, which includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, or a phosphonic acid group and its derivatives. The substituent G can ionize to produce negative ions, which then adsorb onto the surface of the positive electrode material through positive and negative charge interactions, causing electrostatic repulsion between the positive electrode material particles and achieving dispersion. Alternatively, the substituent G can be a polar group, generating strong interaction forces with the surface of the positive electrode material, maintaining a certain distance between the positive electrode material particles, thereby further improving the dispersion effect of the dispersant / binder.

[0009] In one embodiment, G is a terminal group of the cyano polymer. This configuration allows the dispersant binder to interact better with the cathode material, improving the dispersion effect.

[0010] In one embodiment, at least some of the carbon-carbon double bonds in the cyanopolymer are hydrogenated to carbon-carbon single bonds. In structural unit B of the cyanopolymer, at least some of the carbon-carbon double bonds are hydrogenated to carbon-carbon single bonds, at which point the hydrogenated butadiene is a freely rotating flexible segment, which can further improve the flexibility of the positive electrode sheet.

[0011] In one embodiment, the weight-average molecular weight of the dispersant binder is 10,000-1,000,000. A larger molecular weight of the dispersant binder can generate a stronger steric hindrance, allowing the cathode material particles to be fully dispersed while reducing their re-agglomeration.

[0012] In one embodiment, the weight-average molecular weight of the dispersant binder is 50,000-500,000. When the weight-average molecular weight of the dispersant binder is within this range, it can further disperse the cathode material particles through physical isolation, while simultaneously reducing the re-agglomeration of the dispersed particles.

[0013] In one embodiment, the carboxyl group in the substituent R' has the following chemical formula: The chemical formula of and / or ester group is or The chemical formula of and / or hydroxyl group is The chemical formulas of and / or alkoxy groups are: The chemical formula of the and / or amide group is

[0014] Wherein, n takes the value of 0-12; R1 is selected from any one of alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether polyoxypropylene ether copolymer groups; R2 is selected from any one of H, alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether polyoxypropylene ether copolymer groups.

[0015] The polar groups in the substituent R' can interact with the cathode material, maintaining a certain distance between cathode material particles and achieving good dispersion of the cathode material; the carbon atom chains in the substituent R' can extend in the dispersion medium, creating steric barriers between cathode material particles adsorbed with dispersing binders; R1 and R2 can endow the substituent R' with different polarities and chain segments, which can meet the dispersion requirements of different cathode material systems and generate different adsorption forces with different particles in the cathode material system.

[0016] In one embodiment, the carboxylate in the substituent R' has the following chemical formula: The chemical formula of the and / or amide group is The chemical formula of the and / or amino group is The chemical formulas of and / or ammonium salts are:

[0017] Wherein, n takes the value of 0-12; R3, R4, and R5 are selected from any one of H, alkyl with 1-18 carbon atoms, aryl with 6-18 carbon atoms, polyoxyethylene ether group, and polyoxyethylene ether polyoxypropylene ether copolymer group.

[0018] The polar groups in the substituent R' can interact with the cathode material, maintaining a certain distance between cathode material particles and achieving good dispersion of the cathode material; the carbon atom chains in the substituent R' can extend in the dispersion medium, creating steric barriers between cathode material particles adsorbed with dispersing binders; R3, R4, and R5 can endow the substituent R' with different polarities and chain segments, which can meet the dispersion requirements of different cathode material systems and generate different adsorption forces with different particles in the cathode material system.

[0019] In one embodiment, the polyoxyethylene ether group is The value of h ranges from 1 to 20; and / or the polyoxyethylene ether / polyoxypropylene ether copolymer group is... The value of k ranges from 1 to 15, and the value of l ranges from 1 to 10. Polyoxyethylene ether groups and polyoxyethylene ether polyoxypropylene ether copolymer groups can be used as solvation segments. When the degree of polymerization is within the above range, they have a good solvation effect, which is beneficial to improving dispersion performance.

[0020] In one embodiment, the chemical formula of the carboxylic acid group and its derivatives is:

[0021] Where m takes values ​​greater than 1 and less than or equal to 12, and R” is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, and aromatic ester group; the chemical formula of alkyl group is The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0022] C m The carbon atom chain can act as a solvation segment to achieve a solvation effect; when R” is H, the above group can ionize to produce negative ions, which can then adsorb onto the surface of the positive electrode material through the interaction of positive and negative charges, causing electrostatic repulsion between the positive electrode material particles to achieve the purpose of dispersion; when R” is alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group and aromatic ester group, it can increase the polarity of the substituent group G, generate a stronger interaction force with the surface of the positive electrode material, keep a certain distance between the positive electrode material particles, and thus further improve the dispersion effect of the dispersant binder.

[0023] In one embodiment, the chemical formula of the sulfonic acid group and its derivatives is:

[0024] Where m takes values ​​greater than 1 and less than or equal to 12, and R” is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, and aromatic ester group; the chemical formula of alkyl group is The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0025] C m The carbon atom chain can act as a solvation segment to achieve a solvation effect; when R” is H, the above group can ionize to produce negative ions, which can then adsorb onto the surface of the positive electrode material through the interaction of positive and negative charges, causing electrostatic repulsion between the positive electrode material particles to achieve the purpose of dispersion; when R” is alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group and aromatic ester group, it can increase the polarity of the substituent group G, generate a stronger interaction force with the surface of the positive electrode material, keep a certain distance between the positive electrode material particles, and thus further improve the dispersion effect of the dispersant binder.

[0026] In one embodiment, the phosphonic acid group and its derivatives include diester phosphonic acid and its derivatives or monoester phosphonic acid and its derivatives, wherein the chemical formula of diester phosphonic acid and its derivatives is [insert chemical formula here]. The chemical formulas of monophosphonic acid esters and their derivatives are as follows:

[0027] Wherein, R” is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, and aromatic ester group; the chemical formula of alkyl group is The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0028] When R" is H, the above-mentioned groups can ionize to produce negative ions, which then adsorb onto the surface of the positive electrode material through the interaction of positive and negative charges, causing electrostatic repulsion between the positive electrode material particles and achieving the purpose of dispersion. When R" is alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester, or aromatic ester, the polarity of the substituent group G can be increased, generating a stronger interaction force with the surface of the positive electrode material, keeping a certain distance between the positive electrode material particles, thereby further improving the dispersion effect of the dispersant binder.

[0029] In one embodiment, the dispersion adhesive comprises a structure as shown in formula (1):

[0030]

[0031] Where R is The mixed structure; the range of a:b is 1:2-1:8, and the range of a:c is 10:1-1:10.

[0032] When the above-described dispersant binder is applied to the positive electrode slurry, it can provide both dispersion and adhesion, improve the dispersibility of the positive electrode slurry, and enhance the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity and stability.

[0033] In one embodiment, the positive electrode active material includes one or more of lithium iron phosphate and lithium manganese iron phosphate. The aforementioned positive electrode active material interacts with the dispersant and binder in the positive electrode material layer, maintaining a certain distance between the positive electrode active material particles and achieving good dispersion.

[0034] In one embodiment, the film resistance of the positive electrode is 0.05Ω-0.50Ω. The low film resistance of the positive electrode helps to reduce the internal resistance of the battery.

[0035] To address the aforementioned technical problems, another technical solution adopted in this application is to provide a positive electrode slurry, comprising a positive electrode active material, a dispersant / binder, and a solvent. The dispersant / binder comprises a cyanopolymer, which includes structural units A derived from acrylonitrile, structural units B derived from butadiene, and structural units C derived from substituted olefins. The substituted olefins include at least one substituent R', where R' comprises at least one of an alkyl group with 1-18 carbon atoms, an aryl group with 6-18 carbon atoms, a carboxyl group, an ester group, a carboxylate group, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt. The above-mentioned positive electrode slurry exhibits good dispersibility, which is beneficial for improving the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity and stability.

[0036] In one embodiment, the dispersant binder accounts for 0.01%-3.0% of the total weight of the positive electrode slurry. When the dispersant binder accounts for a portion of the total weight of the positive electrode slurry within this range, both the flexibility of the positive electrode sheet and the energy density of the battery can be balanced.

[0037] In one embodiment, the dispersant binder accounts for 0.03%-2.0% of the total weight of the positive electrode slurry. When the dispersant binder accounts for a portion of the total weight of the positive electrode slurry within this range, it is possible to further balance the flexibility of the positive electrode sheet and the energy density of the battery.

[0038] In one embodiment, the viscosity of the positive electrode slurry is 4000 mPa·s-30000 mPa·s. When the viscosity of the positive electrode slurry is within this range, the slurry is less prone to sedimentation and has good dispersibility. Simultaneously, the slurry has good leveling properties, which facilitates coating.

[0039] In one embodiment, the solid content of the positive electrode slurry is 55%-65%. This solid content is beneficial for improving the stability of the positive electrode slurry, and can also reduce the coating thickness and lower the battery internal resistance.

[0040] To address the aforementioned technical problems, another technical solution adopted in this application is to provide a dispersing binder comprising a cyano polymer, wherein the cyano polymer comprises a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene, and a structural unit C derived from a substituted olefin; wherein the substituted olefin comprises at least one substituent R', and R' comprises at least one of an alkyl group having 1-18 carbon atoms, an aryl group having 6-18 carbon atoms, a carboxyl group, an ester group, a carboxyl salt, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt. The dispersing binder can simultaneously provide dispersion and adhesion, improving the dispersibility of the positive electrode slurry and enhancing the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity and stability.

[0041] In one embodiment, the cyano polymer further includes at least one substituent G, which includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, or a phosphonic acid group and its derivatives. The substituent G can further improve the dispersing effect of the dispersing adhesive.

[0042] To address the aforementioned technical problems, another technical solution adopted in this application is: a method for preparing a dispersant binder, comprising the following steps: providing acrylonitrile monomers, butadiene monomers, and substituted olefin monomers; the substituted olefins include at least one substituent group R', wherein R' comprises at least one of an alkyl group with 1-18 carbon atoms, an aryl group with 6-18 carbon atoms, a carboxyl group, an ester group, a carboxyl salt, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt; mixing the acrylonitrile monomers, butadiene monomers, and substituted olefin monomers with an initiator to carry out a polymerization reaction to obtain a cyano polymer. The dispersant binder prepared by the above method can simultaneously provide dispersion and adhesion, improve the dispersibility of the positive electrode slurry, and improve the flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity and stability.

[0043] In one embodiment, the method further includes: adding a capping agent to the polymerization reaction to stop the polymerization and obtain a hydroxyl polymer, the capping agent including ethylene oxide; reacting the hydroxyl polymer with a halogen-substituted compound containing a substituent group G to obtain a cyano polymer containing a substituent group G; the substituent group G includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, and a phosphonic acid group and its derivatives. The substituent group G can enhance the adsorption of the dispersant and binder and the cathode material particles, thereby further improving the dispersion effect of the dispersant and binder.

[0044] In one embodiment, the method for preparing the dispersing adhesive further includes: hydrogenating a cyanopolymer or a hydroxyl polymer. During this process, a portion of the butadiene monomer is hydrogenated and reduced to... The structure consists of freely rotating flexible chain segments, which can further improve the flexibility of the positive electrode sheet.

[0045] In one embodiment, the molar ratio of acrylonitrile monomers to butadiene monomers in the monomer raw materials is (1:2)-(1:8), and the molar ratio of acrylonitrile monomers to substituted olefin monomers is (10:1)-(1:10). With the above settings, the prepared dispersant adhesive has better dispersion and softening effects.

[0046] To solve the aforementioned technical problems, another technical solution adopted in this application is to provide an electrical device that includes the aforementioned battery. The electrical device has at least the same advantages as the battery, namely, improved battery life.

[0047] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is an exploded structural diagram of a battery according to one or more embodiments of this application;

[0050] Figure 2 This is an exploded structural diagram of a battery cell according to one or more embodiments of this application;

[0051] Figure 3 This is a schematic diagram of the structure of a vehicle according to one or more embodiments of this application.

[0052] In the attached image:

[0053] 1000, Vehicle; 300, Motor; 200, Controller; 100, Battery; 10, Housing; 11, First Part; 12, Second Part; 20, Battery Cell; 21, End Cap; 21a, Electrode Terminal; 22, Housing; 23, Electrode Assembly. Detailed Implementation

[0054] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the embodiments of the technical solutions of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0056] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0057] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0058] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0059] Quantities, ratios, and other numerical values ​​are presented in range format in this document. It should be understood that this range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0060] Unless otherwise specified, all steps of this application may be performed sequentially, randomly, or in parallel, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially, or steps (a) and (b) may be performed simultaneously in parallel. For example, the method may also include step (c), indicating 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.

[0061] Lithium-ion batteries, as a new type of green rechargeable battery, are widely used in electric vehicles, energy storage systems, and renewable energy fields. With the new development of lithium-ion batteries in my country, they will inevitably achieve improvements in many aspects.

[0062] Please refer to Figure 1 , Figure 1 This is an exploded structural diagram of a battery according to one or more embodiments. The battery 100 includes a housing 10 and a battery cell 20, the battery cell 20 being housed within the housing 10. The housing 10 provides a accommodating space for the battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 overlapping each other, together defining a accommodating space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the accommodating space; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0063] In battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. Battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0064] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0065] Please refer to Figure 2 , Figure 2 This is an exploded structural diagram of a battery cell according to one or more embodiments. Battery cell 20 refers to the smallest unit that makes up the battery. Figure 2 The battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0066] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved safety performance. Functional components such as electrode terminals 21a can be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0067] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0068] Electrode assembly 23 is the component in the battery cell 100 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly, while the portions of the positive and negative electrode sheets without active material each constitute a tab 23a. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs 23a connect to the electrode terminals to form a current loop.

[0069] In some embodiments, the positive electrode includes a current collector and a layer of positive electrode material disposed on the current collector.

[0070] The positive electrode material layer includes a positive electrode active material, which may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition 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 alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 )), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0071] Preferably, the positive electrode active material includes lithium manganese iron phosphate (LiFe). x Mn 1-x Lithium iron phosphate (LiPO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), and high-nickel layered materials Li 1+y (Ni a Co b Mn 1-a-b-c B c ) 1-y O2; where 0.05≤y≤0.05, 0.85≤a≤0.95, 0.01≤b≤0.10, 0≤c≤0.05, and B is Zn. 2+ Mg 2+ Al 3+ Cr 3+ ,Sc 3+ Ga 3+ La 3+ Sm 3+ Ti 4+ Zr 4+ Nb 5+ W 6+ One or more of them.

[0072] In one embodiment, the active layer of the positive electrode material further includes a conductive agent and a binder; the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black, and acetylene black; the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0073] The conductive agent imparts conductivity to the electrode. The positive electrode conductive material can include any conductive material as long as it does not cause a chemical change. Non-limiting examples of positive electrode conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof. Optionally, the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black, and acetylene black.

[0074] The adhesive improves the adhesion stability of the active layer and reduces the probability of powder shedding. The adhesive can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). Optionally, the adhesive includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0075] In one embodiment, the active layer of the positive electrode material further includes the dispersant binder of any of the foregoing embodiments, or the dispersant binder prepared using the preparation method of the dispersant binder of any of the foregoing embodiments. The dispersant binder is beneficial for improving the uniformity and flexibility of the positive electrode sheet.

[0076] In some embodiments, the negative electrode includes a current collector and a negative electrode active layer disposed on the current collector.

[0077] The negative electrode active layer includes negative electrode active materials, which include, but are not limited to, carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials, lithium titanate negative electrode materials, and lithium metal negative electrode materials; specifically, including but not limited to graphite materials, silicon-carbon materials, graphite-silicon suboxide materials, nano-silicon materials, silicon suboxide materials, and tin-based materials; more specifically, including natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 One or more of Li-Al alloys.

[0078] In some embodiments, the negative electrode active layer may further include a binder, a conductive agent, and other optional additives. As examples, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As examples, the binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As examples, other optional additives may be thickeners and dispersants (e.g., sodium carboxymethyl cellulose CMC-Na) and PTC thermistor materials.

[0079] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0080] In one embodiment, the electrolyte includes one or more of carbonate solvents and ether solvents.

[0081] Carbonates are typically small-molecule cyclic or chain carbonates; including but not limited to one or more of ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, methyl propyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and fluorocarbonates; and may also be at least one ester solvent selected from γ-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, and fluorocarboxylic acid esters.

[0082] Ether solvents include, but are not limited to, one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyltetrahydrofuran, ethylene oxide, 1,3-dioxolane, fluoroethers, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether, and dibutyl ether.

[0083] In other embodiments, the electrolyte may further comprise any one or a mixture of several of amine solvents, sulfone solvents, and nitrile solvents. Amine solvents include at least one of N-methylacetamide, N-methylformamide, dimethylformamide, and diethylformamide. Sulfone solvents include at least one of dimethyl sulfoxide, sulfolane, diphenyl sulfoxide, thionyl chloride, and dipropyl sulfone. Nitrile solvents include at least one of acetonitrile, succinic anionizer, adiponitrile, and glutaronitrile. A high-voltage resistant electrolyte is preferred, as its acidity decreases under high voltage, facilitating the transport of active ions, significantly reducing side reactions on the electrode surface, and improving battery stability.

[0084] In some embodiments, the electrolyte further includes an electrolyte salt, which 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0085] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0086] As mentioned earlier, the electrode assembly is the component in a battery cell where electrochemical reactions occur. The electrode assembly is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The positive electrode sheet includes a current collector and a positive electrode material layer disposed on at least one side of the current collector. The positive electrode material layer includes a positive electrode active material, a conductive agent, and a binder. In the preparation of the positive electrode sheet, the positive electrode active material, conductive agent, and binder are first thoroughly mixed in a solvent to obtain a positive electrode slurry; then, the positive electrode slurry is coated onto the current collector, dried, and cold-pressed to obtain the positive electrode sheet.

[0087] Therefore, the properties of the cathode slurry significantly affect the performance of the cathode electrode. In the cathode slurry, the solid content affects its stability; within a certain range, the higher the solid content, the higher the stability. Furthermore, a high solid content slurry can reduce coating thickness and lower battery internal resistance. However, high solid content slurries have insufficient dispersibility and are prone to gelation, which reduces the uniformity of the cathode electrode and leads to battery capacity loss.

[0088] Furthermore, increasing the coating thickness of the positive electrode slurry and the compaction density of the positive electrode sheet are beneficial to improving the energy density and first-time efficiency of the battery. However, with a large coating thickness and high compaction density, the flexibility of the positive electrode sheet will decrease, leading to reduced stability and increased susceptibility to cracking.

[0089] Accordingly, this application provides a dispersant binder that improves the dispersibility of the positive electrode slurry while also improving the flexibility of the positive electrode sheet. This dispersant binder can be applied to the positive electrode sheet of a battery. Specifically, this application provides a battery comprising a positive electrode sheet, which includes a current collector and a positive electrode material layer disposed on at least one side of the current collector. The positive electrode material layer includes a positive electrode active material and a dispersant binder. The dispersant binder comprises a cyano polymer, which includes a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene, and a structural unit C derived from a substituted olefin. The substituted olefin includes at least one substituent R', which includes at least one of an alkyl group with 1-18 carbon atoms, an aryl group with 6-18 carbon atoms, a carboxyl group, an ester group, a carboxylate, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt.

[0090] The substituent groups on the dispersant binder, including cyano groups and substituent groups R', can be adsorbed onto the surface of the cathode material particles through interactions such as ionic bonds, hydrogen bonds, and van der Waals forces. At the same time, the solvated segments of the dispersant binder have good compatibility with the dispersion medium of the cathode slurry (usually an organic solvent, such as N-methylpyrrolidone), and can extend in the dispersion medium, resulting in steric barriers between the cathode material particles adsorbed with the dispersant binder, thereby achieving stable dispersion of the cathode material in the dispersion medium.

[0091] Specifically, derived from acrylonitrile The structural unit A can be represented as The cyano group (-CN) is highly polar and can interact with polar cathode materials, adsorbing onto the surface of the cathode material and maintaining a certain distance between cathode material particles, thus achieving good dispersion of the cathode material.

[0092] In one embodiment, the number of cyano groups in the cyano polymer can be controlled by adjusting the number of structural unit A in the cyano polymer. Different numbers of cyano groups result in different polarities of the cyano polymer and different interactions with the cathode material, thus satisfying the dispersion requirements of cathode slurries with different polarity conditions.

[0093] Derived from substituted olefins The structural unit C can be represented as The substituent group R' on structural unit C includes both polar and nonpolar groups. A substituted alkene can have one or more substituent groups R', meaning the substituted alkene can be... R' can be the same substituent group or different substituent groups.

[0094] R' includes at least one of the following: alkyl with 1-18 carbon atoms, aryl, carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, or ammonium salt with 6-18 carbon atoms. For example, polar substituents R' can be carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, or ammonium salts, while nonpolar substituents R' can be alkyl, phenyl, etc. Substituents of different polarities can adsorb onto cathode materials of different polarities, achieving good dispersion of cathode material particles; R' can extend in the dispersion medium, creating steric hindrance between cathode material particles adsorbed with dispersing binders.

[0095] Meanwhile, the dispersant binder also helps to improve the flexibility of the positive electrode sheet. First, it provides adhesion performance through the strong attraction between some polar groups and positive electrode material particles, reducing the use of rigid binders and thus indirectly improving the flexibility of the positive electrode sheet. Second, it improves the flexibility of the positive electrode sheet through the flexible segments in the structure of the dispersant binder.

[0096] Specifically, on the one hand, the nitrogen atom in the cyano group can coordinate with the positive electrode active material. For example, the nitrogen atom can coordinate with the iron atom in the positive electrode active material lithium iron phosphate (LFP), thereby generating a strong attraction. The nitrogen atom in the cyano group can also form hydrogen bonds with the active hydrogen atoms bonded to heteroatoms on the substrate undercoat, thereby increasing the adhesion between positive electrode active material particles and between particles and the substrate, thus providing adhesive properties.

[0097] In existing technologies, the binder in the positive electrode sheet is usually polyvinylidene fluoride (PVDF). PVDF itself has a large molecular weight and high crystallinity, and it does not easily slip within the positive electrode sheet, leading to poor flexibility. The dispersant binder of this application can replace part of the PVDF for bonding, thereby reducing the amount of PVDF used and improving the flexibility of the positive electrode sheet. By adding the dispersant binder of this application, the amount of PVDF used can be reduced by 20%-50%. That is, in the scheme of this application, in addition to the dispersant binder of this application, conventional dispersants and binders can also be added to the positive electrode sheet.

[0098] On the other hand, it originates from butadiene The structural unit B can be represented as In one embodiment, at least a portion of the carbon-carbon double bonds in the cyanopolymer are hydrogenated to carbon-carbon single bonds. That is, at least a portion of the carbon-carbon double bonds in structural unit B are hydrogenated to carbon-carbon single bonds. The structure was reduced to Structure. At this point, the hydrogenated butadiene is a flexible chain segment that can rotate freely, which can further improve the flexibility of the positive electrode sheet.

[0099] In one embodiment, the proportion of structural unit B reduced to carbon-carbon single bonds by hydrogenation can be controlled by adjusting the hydrogenation reaction time and hydrogen gas pressure. This allows for adaptive adjustment of the cathode electrode's flexibility according to different cathode material systems and battery application scenarios.

[0100] In summary, dispersants and binders can simultaneously provide dispersion and adhesion, improving the dispersibility of the positive electrode slurry and enhancing the flexibility of the positive electrode sheet. Therefore, they can address the problem of insufficient dispersibility in high-solids-content positive electrode slurries, improve the uniformity of the positive electrode sheet, and reduce battery capacity loss. Furthermore, when the positive electrode sheet coating thickness is large and the compaction density is high, they can reduce the probability of positive electrode sheet cracking and improve battery stability.

[0101] In other words, by adding the dispersant and binder of this application to the positive electrode slurry, a positive electrode sheet with a large coating thickness and high compaction density can be prepared, which is beneficial to improving the energy density and first efficiency of the battery.

[0102] In one embodiment, in the cyanopolymer, the molar percentage of structural unit A is 10%-30%, the molar percentage of structural unit B is 60%-80%, and the molar percentage of structural unit C is 10%-20%. For example, the molar percentage of structural unit A is 10%, 15%, 20%, 25%, 30%, etc.; the molar percentage of structural unit B is 60%, 65%, 70%, 75%, 80%, etc.; and the molar percentage of structural unit C is 10%, 15%, 20%, etc. When the molar percentage of each structural unit in the cyanopolymer is within the above range, it can enable good adsorption between the dispersant / binder and the positive electrode material particles, and between the dispersant / binder and the dispersion medium, thereby achieving a better dispersion effect; providing better adhesion performance; and simultaneously giving the polymer molecular chain better flexibility.

[0103] In one embodiment, the dispersibility of the binder can be controlled by adjusting the number of cyano groups to suit different types of cathode active materials. For different lithium iron phosphate (LFP) coating surfaces, the hydrogenation ratio of the cyano polymer backbone segments and the number of cyano groups can be adjusted to improve the dispersion effect.

[0104] In one embodiment, the cyano polymer further includes at least one substituent group G, which includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, or a phosphonic acid group and its derivatives.

[0105] In some embodiments, the substituent G is any one of a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group. In this case, the substituent G can ionize into negative ions. Different substituent Gs ionize into different types of negative ions. By controlling the type of substituent G, different types of negative ions can be ionized, and the forces generated are also different. This allows for adsorption onto the surface of positive electrode materials of different polarities through the interaction of positive and negative charges, causing electrostatic repulsion between the positive electrode material particles and achieving dispersion.

[0106] In some embodiments, the substituent G is any one of a carboxylic acid group derivative, a sulfonic acid group derivative, or a phosphonic acid group derivative. When the active hydrogen on the carboxylic acid group, sulfonic acid group, or phosphonic acid group is replaced by other substituents, derivatives of the corresponding groups are obtained. In this case, the substituent G is a polar group, which can generate strong interaction forces with the surface of the positive electrode material, maintaining a certain distance between the positive electrode material particles, thereby improving the dispersion effect of the dispersant binder.

[0107] For example, the substituent group G can form hydrogen bonds with the phosphate groups on the surface of positive electrode active materials such as lithium iron phosphate and lithium manganese iron phosphate, and generate intermolecular forces with the strongly polar groups on the surface of ternary positive electrode active materials; it can also form hydrogen bonds with functional groups such as hydroxyl and carboxyl groups on the surface of conductive agents such as carbon nanotubes and graphene.

[0108] In one embodiment, the substituent G may further include a cationic group or an aromatic nonpolar group. The cationic group can generate electrostatic interactions with the negatively charged positive electrode material, causing electrostatic repulsion between the positive electrode material particles, thus achieving dispersion. The aromatic nonpolar group has excellent adsorption properties for carbon-coated positive electrode active materials, enabling the particles of such positive electrode active materials to maintain a certain distance, thereby further improving the dispersion effect of the dispersant / binder.

[0109] In one embodiment, the dispersing ability of the dispersant can be controlled by adjusting the type of substituent G to suit different types of cathode active materials. For different lithium iron phosphate (LFP) coating surfaces, more types of substituent G can be selected, such as cationic substituent G or aromatic nonpolar substituent G, the latter exhibiting superior adsorption for the carbon coating layer. Furthermore, polymers with multiple substituent Gs can be designed, or dispersants with different substituent G types can be mixed for further adjustment. That is, the dispersant used in the cathode slurry can include various different cyano polymers, or the dispersant can be a mixture of cyano polymers. Different cyano polymers can each include different substituent Gs to adaptably meet the application requirements of cathode slurries in different material systems.

[0110] In one embodiment, G is a terminal group of the cyanopolymer. A terminal group refers to a group at the end of a polymer molecule chain. Therefore, a cyanopolymer molecule has a maximum of 2 Gs, preferably 1 G. This configuration allows the dispersant binder to interact better with the cathode material, improving the dispersion effect.

[0111] In one embodiment, a cyano polymer may be synthesized first, and then a substituent group G may be introduced at the end of the cyano polymer. For example, the cyano polymer may have active end groups such as hydroxyl groups, and the active end groups react with the halogenated product to introduce the group G.

[0112] In one embodiment, the weight-average molecular weight of the dispersing adhesive is 10,000-1,000,000. For example, it can be 10,000, 30,000, 100,000, 250,000, 500,000, 700,000, 850,000, 900,000, 1,000,000, etc., or a range of any two of the above values, such as 10,000-30,000, 250,000-500,000, 700,000-850,000, 900,000-1,000,000, etc.

[0113] Because cyanopolymers are obtained through linear polymerization, the molecular weight of the dispersant binder is relatively large, reaching the millions. High molecular weight polymers can generate strong steric hindrance, allowing the cathode material particles to be fully dispersed while reducing their re-agglomeration.

[0114] In one embodiment, the weight-average molecular weight of the dispersant binder is 50,000-500,000. For example, it can be 50,000, 60,000, 80,000, 100,000, 200,000, 250,000, 400,000, 500,000, etc., or a range consisting of any two of the above values, such as 50,000-60,000, 80,000-100,000, 200,000-250,000, 400,000-500,000, etc. When the weight-average molecular weight of the dispersant binder is within the above range, it can further disperse the cathode material particles through physical isolation, while reducing the re-agglomeration of the dispersed particles.

[0115] Furthermore, by designing the structures of the substituents R' and G, this application enables the dispersing adhesive to achieve better dispersion and bonding effects.

[0116] In one embodiment, the carboxyl group in the substituent R' has the following chemical formula: The chemical formula of and / or ester group is The chemical formula of and / or hydroxyl group is The chemical formulas of and / or alkoxy groups are: The chemical formula of the and / or amide group is

[0117] Wherein, n takes the value of 0-12; R1 is selected from any one of alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether polyoxypropylene ether copolymer groups; R2 is selected from any one of hydrogen, alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether polyoxypropylene ether copolymer groups.

[0118] In one embodiment, the carboxylate in the substituent R' has the following chemical formula: A + for The chemical formula of the and / or amide group is The chemical formula of the and / or amino group is The chemical formulas of and / or ammonium salts are:

[0119] Wherein, n takes the value of 0-12; R3, R4, and R5 are selected from any one of H, alkyl with 1-18 carbon atoms, aryl with 6-18 carbon atoms, polyoxyethylene ether group, and polyoxyethylene ether polyoxypropylene ether copolymer group.

[0120] Among the substituents R', carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, and ammonium salts are polar groups that can interact with polar cathode materials, maintaining a certain distance between cathode material particles and achieving good dispersion of the cathode material.

[0121] In the chemical formulas of the above carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, and ammonium salts, the substituent group R' has a C at one end connected to the cyano polymer backbone. n A carbon atom chain, with the number of carbon atoms ranging from 0 to 12, C n The carbon atom chain can be an alkyl chain. When the number of carbon atoms is 0, the substituent group R' is directly connected to the cyano polymer backbone; when the number of carbon atoms is 1-12, the carbon atom chain can extend in the dispersion medium as a solvation segment, creating steric barriers between the cathode material particles adsorbed with the dispersing binder, thereby achieving stable dispersion of the cathode material in the dispersion medium.

[0122] At the end of the substituted group R' furthest from the cyano polymer backbone, at least one of the following groups, R1, R2, R3, R4, and R5, is present. When two or three of the following groups, R1, R2, R3, R4, and R5, are present, the groups may be the same or different.

[0123] Specifically, R1 is selected from any one of the following: alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether polyoxypropylene ether copolymer groups;

[0124] R2, R3, R4, and R5 are selected from H, alkyl groups with 1-18 carbon atoms, aryl groups with 6-18 carbon atoms, polyoxyethylene ether groups, and polyoxyethylene ether / polyoxypropylene ether copolymer groups, respectively. R1, R2, and R3 can impart different polarities to the substituent group R', which can meet the dispersion requirements of different cathode material systems.

[0125] In one embodiment, R1, R2, R3, R4, and R5 are selected from any one of alkyl groups with 1-18 carbon atoms and aryl groups with 6-18 carbon atoms. The steric hindrance created by the alkyl and aryl chains causes the cathode material particles to bounce away from each other, thereby achieving stable dispersion of the particles in the medium.

[0126] In some embodiments, the substituent R' can ionize to release hydrogen ions. For example, R' is a carboxyl group. In this case, the substituent R' can exert a strong adsorption effect on the surface of the cathode material with different polarities through the interaction of positive and negative charges, causing electrostatic repulsion between the cathode material particles and achieving the purpose of dispersion.

[0127] In some embodiments, the substituent group R' can form hydrogen bonds with the cathode material particles. For example, R' is a hydroxyl group, and at least one of R3 and R4 is an amino group with an hydroxyl group (H). At least one of R3 and R4 is an amide group with an hydroxyl group (H). R3, R4, and R5 are ammonium salts in which at least one is H. In this case, the substituent group R' can generate a strong adsorption effect on the surface of cathode materials with different polarities through hydrogen bonds, separating the cathode material particles and achieving the purpose of dispersion.

[0128] In some embodiments, the substituent R' has either a polyoxyethylene ether group or a polyoxyethylene ether-polyoxypropylene ether copolymer group. In this case, the polyoxyethylene ether group and the polyoxyethylene ether-polyoxypropylene ether copolymer group can act as solvation segments, exhibiting good solvation effects. They diffuse into the medium, forming a charged protective barrier around the cathode material particles, causing electrostatic repulsion between the particles and stabilizing the dispersion. Simultaneously, the spatial barrier of the solvation chain causes the particles to bounce away from each other, thereby achieving stable dispersion of the particles in the medium.

[0129] In one embodiment, the polyoxyethylene ether group is The value of h ranges from 1 to 20; and / or the polyoxyethylene ether / polyoxypropylene ether copolymer group is... The value of k is 1-15, and the value of l is 1-10.

[0130] In the above embodiments, the degree of polymerization of the polyoxyethylene ether in the polyoxyethylene ether group is 1-20; the degree of polymerization of the polyoxyethylene ether-polyoxypropylene ether copolymer group is 1-15 for the polyoxyethylene ether and 1-10 for the polyoxypropylene ether. The polyoxyethylene ether group and the polyoxyethylene ether-polyoxypropylene ether copolymer group can serve as solvation segments, and a degree of polymerization within the above range provides a good solvation effect, which is beneficial for improving dispersion performance.

[0131] The polymer chains of polyoxyethylene ether and polyoxyethylene ether-polyoxypropylene ether copolymers are hydroxyl-terminated and bonded to substituents R' via hydroxyl groups. For example, when substituent R' is an ester group, the bonding occurs through an esterification reaction.

[0132] In one embodiment, the chemical formula of the substituent group G, specifically the carboxylic acid group and its derivatives, is:

[0133] Where m takes values ​​greater than 1 and less than or equal to 12, i.e., Cm C represents a chain of carbon atoms with 0-12 carbon atoms. m The carbon chain can be an alkyl chain. "R" is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester, or aromatic ester; the chemical formula of the alkyl group is... The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0134] In one embodiment, the chemical formula of the sulfonic acid group and its derivatives in the substituent group G is:

[0135] Where m takes values ​​greater than 1 and less than or equal to 12, and R” is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, and aromatic ester group; the chemical formula of alkyl group is The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0136] In one embodiment, the phosphonic acid group and its derivatives in the substituent group G include diester phosphonic acid and its derivatives or monoester phosphonic acid and its derivatives, wherein the chemical formula of diester phosphonic acid and its derivatives is [insert chemical formula here]. The chemical formulas of monophosphonic acid esters and their derivatives are as follows:

[0137] Wherein, R” is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, and aromatic ester group; the chemical formula of alkyl group is The chemical formula of alkyl alcohols is The chemical formula of alkyl hydroxylamine is The chemical formula of the fatty ester group is The chemical formula of the aromatic ester group is: The value of p is 1-12, the value of q is 1-16, and the number of carbon atoms in Ar does not exceed 12.

[0138] In one embodiment, diester phosphonic acid and its derivatives are flanked by symmetrical cyano polymer segments.

[0139] Substituent group G, acting as an anchoring group, can be adsorbed onto the surface of cathode material particles through ionic bonds, hydrogen bonds, and van der Waals forces, maintaining a certain distance between the cathode material particles and thus further improving the dispersion effect of the dispersant binder.

[0140] In the chemical formulas of carboxylic acid groups and their derivatives, and sulfonic acid groups and their derivatives, the substituted group G has a C at one end connected to the cyano polymer backbone. m A carbon atom chain, with the number of carbon atoms greater than 1 and less than or equal to 12. The carbon atom chain can have a solvation effect.

[0141] In the chemical formulas of carboxylic acid groups and their derivatives, sulfonic acid groups and their derivatives, and phosphonic acid groups and their derivatives, the substituent group G is located away from one end of the cyano polymer backbone, and an R" group is present.

[0142] Specifically, when R” is H, the substituent group G can ionize to produce negative ions, which then adsorb onto the surface of the polar positive electrode material through the interaction of positive and negative charges, causing electrostatic repulsion between the positive electrode material particles and achieving the purpose of dispersion. When R” is alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester, or aromatic ester, the polarity of the substituent group G can be increased, generating a stronger interaction force with the surface of the positive electrode material, keeping a certain distance between the positive electrode material particles, thereby further improving the dispersion effect of the dispersant binder.

[0143] In one embodiment, the dispersion adhesive comprises a structure as shown in formula (1):

[0144]

[0146] Where R is The structure is a mixture; the range of a:b is 1:2-1:8, and the range of a:c is 10:1-1:10. Among them, a:b can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, etc.; a:c can be 10:1, 10:3, 10:5, 10:7, 10:9, 1:1, 1:3, 1:5, 1:7, 1:9, 1:10, etc.

[0147] The dispersant and binder with the above structure can achieve good dispersion of the positive electrode material and provide adhesion performance; when applied to the positive electrode sheet, it can improve the stability and flexibility of the positive electrode sheet, thereby reducing the capacity loss of the battery.

[0148] In one embodiment, the positive electrode active material includes one or more of lithium iron phosphate and lithium manganese iron phosphate. The aforementioned positive electrode active material interacts with the dispersant and binder in the positive electrode material layer, maintaining a certain distance between the positive electrode active material particles and achieving good dispersion.

[0149] In one embodiment, the film resistance of the positive electrode is 0.05Ω-0.50Ω. The film resistance of the positive electrode can be 0.05Ω, 0.10Ω, 0.135Ω, 0.15Ω, 0.20Ω, 0.25Ω, 0.30Ω, 0.35Ω, 0.40Ω, 0.50Ω, etc., or a range consisting of any two of the above values, such as 0.05Ω-0.10Ω, 0.135Ω-0.20Ω, 0.30Ω-0.35Ω, 0.40Ω-0.50Ω, etc. A low film resistance of the positive electrode is beneficial for reducing the internal resistance of the battery.

[0150] This application also provides a positive electrode sheet, which includes a current collector and a positive electrode material layer disposed on at least one side of the current collector. The positive electrode material layer includes a positive electrode active material and a dispersing binder. The dispersing binder includes a cyano polymer, which includes a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene, and a structural unit C derived from a substituted olefin. The substituted olefin includes at least one substituent R', which includes at least one of an alkyl group with 1-18 carbon atoms, an aryl group with 6-18 carbon atoms, a carboxyl group, an ester group, a carboxylate, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt. The positive electrode sheet exhibits good uniformity and flexibility; without compromising the structural stability of the positive electrode sheet, the coating thickness and compaction density of the positive electrode sheet can be increased, thereby improving the energy density and first-time efficiency of the battery.

[0151] In one embodiment, the positive electrode active material includes one or more of lithium iron phosphate and lithium manganese iron phosphate. The aforementioned positive electrode active material interacts with the dispersant and binder in the positive electrode material layer, maintaining a certain distance between the positive electrode active material particles and achieving good dispersion.

[0152] In one embodiment, the positive electrode material layer further includes a conductive agent and a binder. The conductive agent includes conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, etc., and the binder includes PVDF, etc.

[0153] In some embodiments, the positive electrode slurry of any of the above embodiments is coated onto the positive electrode current collector, dried in an oven to obtain a positive electrode film, and then cold-pressed according to the designed compaction thickness to obtain a positive electrode sheet.

[0154] This type of positive electrode sheet exhibits good uniformity and flexibility, making it less prone to breakage, thus resulting in high capacity retention and stability of the battery. Furthermore, without compromising the structural stability of the positive electrode sheet, the coating thickness and compaction density can be increased, thereby improving the battery's energy density and initial efficiency.

[0155] This application also provides a positive electrode slurry, comprising a positive electrode active material, a dispersant and binder, and a solvent. The dispersant and binder comprises a cyano polymer, which includes a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene, and a structural unit C derived from a substituted olefin. The substituted olefin includes at least one substituent R', which includes at least one of an alkyl group with 1-18 carbon atoms, an aryl group with 6-18 carbon atoms, a carboxyl group, an ester group, a carboxylate group, an amide group, a hydroxyl group, an alkoxy group, an amino group, or an ammonium salt. The above-mentioned positive electrode slurry exhibits good dispersibility, which is beneficial for improving the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity retention and stability.

[0156] In one embodiment, the dispersing binder accounts for 0.01%-3.0% of the total weight of the positive electrode slurry. For example, it can be 0.01%, 0.05%, 0.1%, 0.16%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, etc., or a range of any two of the above values, such as 0.01%-0.05%, 0.1%-0.16%, 0.1%-0.2%, 0.8%-1.0%, 2.5%-3.0%, etc.

[0157] When the weight of the dispersant binder in the positive electrode slurry is within the above-mentioned range, the positive electrode slurry can achieve a better dispersion effect and improve the flexibility of the positive electrode sheet. At the same time, reducing the impact of the dispersant binder on the proportion of positive electrode active material is beneficial to increasing the mass proportion of positive electrode active material and improving the energy density and specific capacity of the battery.

[0158] In one embodiment, the dispersing binder accounts for 0.03%-2.0% of the total weight of the positive electrode slurry. For example, it can be 0.03%, 0.05%, 0.1%, 0.16%, 0.2%, 0.25%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, etc., or a range of any two of the above values, such as 0.03%-0.05%, 0.1%-0.16%, 0.2%-0.25%, 0.8%-1.0%, 1.5%-2.0%, etc.

[0159] When the weight of the dispersant binder in the positive electrode slurry is within the above-mentioned range, the positive electrode slurry achieves a better dispersion effect and reduces the impact of the dispersant binder on the proportion of positive electrode active material, which is conducive to increasing the mass proportion of positive electrode active material and improving the energy density and specific capacity of the battery.

[0160] In one embodiment, the viscosity of the positive electrode slurry is 4000 mPa·s-30000 mPa·s. For example, it could be 4000 mPa·s, 4500 mPa·s, 5000 mPa·s, 6000 mPa·s, 8000 mPa·s, 10000 mPa·s, 12500 mPa·s, 15000 mPa·s, 20000 mPa·s, 22000 mPa·s, 26000 mPa·s, 29500 mPa·s, 30000 mPa·s, etc., or a range consisting of any two of the above values, such as 4000 mPa·s-4500 mPa·s, 6000 mPa·s-8000 mPa·s, 12500 mPa·s-15000 mPa·s, 22000 mPa·s-26000 mPa·s, 29500 mPa·s-30000 mPa·s, etc.

[0161] When the viscosity of the positive electrode slurry is within the above range, the slurry is not prone to sedimentation and has good dispersibility. At the same time, the slurry has good leveling properties, which is helpful for coating.

[0162] In one embodiment, the solid content of the positive electrode slurry is 55%-65%. For example, it can be 55%, 55.6%, 56.4%, 58%, 60%, 62.3%, 62.5%, 63%, 65%, etc., or a range of any two of the above values, such as 55%-55.6%, 56.4%-60%, 62.3%-65%, etc. The above solid content is beneficial for improving the stability of the positive electrode slurry, and can also reduce the coating thickness and lower the battery's internal resistance.

[0163] In some embodiments, the preparation method of the positive electrode slurry is as follows: the positive electrode active material, conductive agent, binder, dispersant binder, solvent and other functional components are added to the mixing tank in a certain proportion and in a certain order of addition, and after dispersion and mixing, a slurry suspension system is obtained.

[0164] The prepared positive electrode slurry does not separate into layers, has no obvious viscosity rebound upon standing, does not settle when slowly stirred, and does not exhibit gelation.

[0165] This application also provides a dispersing binder comprising a cyano polymer, wherein the cyano polymer comprises a structural unit A derived from acrylonitrile, a structural unit B derived from butadiene, and a structural unit C derived from a substituted olefin; wherein the substituted olefin comprises at least one substituent R', and R' comprises at least one selected from the following groups: alkyl with 1-18 carbon atoms, aryl, carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, or ammonium salt with 6-18 carbon atoms. The dispersing binder can simultaneously provide dispersion and adhesion, improving the dispersibility of the positive electrode slurry, enhancing the uniformity and flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity retention and stability.

[0166] In one embodiment, the cyano polymer further includes at least one substituent G, which includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, or a phosphonic acid group and its derivatives. The substituent G can further improve the dispersing effect of the dispersing adhesive.

[0167] This application also provides a method for preparing a dispersible adhesive, comprising the following steps:

[0168] The method provides acrylonitrile monomers, butadiene monomers, and substituted olefin monomers; the substituted olefins include at least one substituent group R', R' including at least one of alkyl with 1-18 carbon atoms, aryl, carboxyl, ester, carboxylate, amide, hydroxyl, alkoxy, amino, or ammonium salts with 6-18 carbon atoms; the acrylonitrile monomers, butadiene monomers, and substituted olefin monomers are mixed with an initiator to carry out a polymerization reaction to obtain a cyano polymer.

[0169] The dispersant binder prepared by the above method can provide both dispersion and adhesion, improve the dispersibility of the positive electrode slurry, and enhance the flexibility of the positive electrode sheet, thereby enabling the battery to have higher capacity retention and stability.

[0170] In one embodiment, the method for preparing the dispersible adhesive further includes: adding a capping agent to the polymerization reaction to stop the polymerization and obtain a hydroxy polymer, wherein the capping agent includes ethylene oxide; reacting the hydroxy polymer with a halogen-substituted compound containing a substituent group G to obtain a cyano polymer containing a substituent group G; wherein the substituent group G includes any one of a carboxylic acid group and its derivatives, a sulfonic acid group and its derivatives, or a phosphonic acid group and its derivatives.

[0171] Hydroxyl polymers contain active terminal hydroxyl groups, therefore, substituent G can react with the terminal hydroxyl groups (e.g., esterification) to introduce substituent G into cyano polymers, serving as terminal groups. Substituent G can enhance the adsorption of dispersants and binders and cathode material particles, further improving the dispersion effect of the dispersants and binders.

[0172] In one embodiment, the method for preparing the dispersing adhesive further includes: hydrogenating a cyanopolymer or a hydroxyl polymer. During this process, a portion of the butadiene monomer is hydrogenated and reduced to... The structure consists of freely rotating flexible chain segments, which can further improve the flexibility of the positive electrode sheet.

[0173] In one embodiment, the molar ratio of acrylonitrile monomers to butadiene monomers in the monomer raw materials is (1:2)-(1:8), and the molar ratio of acrylonitrile monomers to substituted olefin monomers is (10:1)-(1:10). With the above settings, the prepared dispersant adhesive has better dispersion and softening effects.

[0174] In some embodiments, this application also provides an electrical device, such as an electrochemical device. The application of this electrochemical device is not particularly limited and can be used in any electronic device known in the prior art. The battery disclosed in the embodiments of this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. That is, an electrical device is provided. In some embodiments, the electrical device of this application can be used in, but is not limited to, laptops, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, ships, spacecraft, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0175] Electrical equipment can be equipped with individual battery cells, battery modules, or battery packs depending on its usage requirements.

[0176] Please refer to Figure 3 , Figure 3 This is a schematic diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0177] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0178] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0179] Example 1:

[0180] (I) Preparation of Dispersed Adhesives

[0181] 1. Linear polymerization is carried out using acrylonitrile, butadiene, and methyl methacrylate as monomer raw materials;

[0182] 2. Using lithium naphthalene as an initiator and tetrahydrofuran as a solvent, the reaction was carried out at 35°C for 12 hours. Finally, ethylene oxide was used as a capping agent to introduce hydroxyl groups. After the reaction was completed, the temperature was lowered to 5°C by an ice-water bath, and then the solvent was evaporated to obtain a cyano polymer with a molecular weight of 500,000. The chemical reaction formula is as follows: the molar ratio of acrylonitrile, butadiene, and methacrylate is 1:6:1, accounting for 12.5%, 75%, and 12.5% ​​of the total molar of monomer raw materials, respectively.

[0183]

[0184] 3. Using palladium as a catalyst, hydrogen gas is introduced to carry out hydrogenation, with a hydrogenation efficiency of 90%-95%. The chemical reaction formula is as follows:

[0185]

[0186] 4. Under alkaline conditions, it reacts with ClC4H9COOH to introduce anchoring groups. The chemical reaction formula is as follows:

[0187]

[0188] (II) Preparation of Lithium-ion Batteries

[0189] 1. Positive electrode active material: lithium iron phosphate; conductive agent: acetylene black; binder: PVDF; dispersant / binder (a:b:c=1:6:1) Weigh the ingredients according to the weight ratio of 97.5:1.5:0.5:0.5, mix them thoroughly in the N-methylpyrrolidone solvent system, and then coat them onto Al foil using extrusion coating or transfer coating. After drying and cold pressing, a positive electrode sheet is obtained.

[0190] 2. The negative electrode active material artificial graphite, conductive agent acetylene black, binder carboxymethyl cellulose, and dispersant styrene-butadiene rubber are thoroughly mixed in a deionized water solvent system at a weight ratio of 96:2:1:1. The mixture is then coated onto Cu foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0191] 3. Using PE porous polymer film as the separator. The positive electrode, separator, and negative electrode are wound in sequence and according to size to form a cell. After encapsulation, electrolyte injection, formation, and degassing, a lithium-ion battery is obtained.

[0192] Examples 2-3:

[0193] The difference from Example 1 is that in Example 2, the molar ratio of acrylonitrile, butadiene, and methacrylate is 1:4:1, accounting for 16.7%, 66.6%, and 16.7% of the total molar of monomer raw materials, respectively. In Example 3, the molar ratio of acrylonitrile, butadiene, and methacrylate is 1:8:1, accounting for 10%, 80%, and 10% of the total molar of monomer raw materials, respectively.

[0194] Examples 4-5:

[0195] The difference from Example 1 is that the conditions of the polymerization reaction were adjusted so that the molecular weight of the dispersing adhesive in Example 4 was 10,000 and the molecular weight of the dispersing adhesive in Example 5 was 1,000,000.

[0196] Examples 6-8:

[0197] The difference from Example 1 is that the substituent group G of the dispersing adhesive is changed. In Example 6, the substituent group G is -C4H9SO3H, and in Example 7, the substituent group G is... Its left and right sides are connected by symmetrical cyano polymer segments, and the substituent G in Example 8 is

[0198] Examples 9-17:

[0199] The difference from Example 1 is that the substituent group R' of the dispersing adhesive is changed. The substituent group R' in Examples 9-17 are -CONH2, -NH2, and -NH2, respectively. -C6H 13 -Ph, -COOH, -COO -+ NH4, -OH, -OCH3.

[0200] Examples 18-19:

[0201] The difference from Example 1 is that the proportion of the dispersant binder to the total weight of the positive electrode slurry is changed; in Example 18 it is 0.01% and in Example 19 it is 3.0%.

[0202] Comparative example:

[0203] 1. The positive electrode active material lithium iron phosphate, conductive agent acetylene black, binder PVDF and dispersant are weighed in a weight ratio of 97.5:1.5:0.5:0.5. After being thoroughly mixed in an N-methylpyrrolidone solvent system, the mixture is coated onto Al foil by extrusion coating or transfer coating, dried and cold pressed to obtain the positive electrode sheet.

[0204] 2. The negative electrode active material artificial graphite, conductive agent acetylene black, binder carboxymethyl cellulose, and dispersant styrene-butadiene rubber are thoroughly mixed in a deionized water solvent system at a weight ratio of 96:2:1:1. The mixture is then coated onto Cu foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0205] 3. Using PE porous polymer film as the separator. The positive electrode, separator, and negative electrode are wound in sequence and according to size to form a cell. After encapsulation, electrolyte injection, formation, and degassing, a lithium-ion battery is obtained.

[0206] Lithium-ion battery performance testing

[0207] 1. Material Characterization

[0208] (1) Infrared characterization of dispersible adhesives

[0209] Measurements were performed using a Bruker Tensor 37 infrared spectrometer. The sample solution was either dropped onto a potassium bromide tablet or mixed together during grinding and then pressed into a tablet using a spectrally pure potassium bromide pellet as a carrier. The infrared scanning range was 4000 cm⁻¹. -1 up to 400cm -1 The scanning resolution is 16cm. -1 Repeat the scan 16 times.

[0210] (2) Weight-average molecular weight test of dispersible adhesives

[0211] A Waters 2695 Isocratic HPLC gel electrophoresis system (differential refractive index detector 2141) was used. A 3.0% polystyrene solution was used as a reference, and a matched column (oil-based: Styragel HT5DMF7.8*300mm + Styragel HT4) was selected. A 3.0% polymer solution was prepared using purified N-methylpyrrolidone (NMP) solvent and allowed to stand for one day. For testing, tetrahydrofuran was first used to flush the syringe, repeated several times. Then, 5 ml of the experimental solution was drawn, air was expelled from the syringe, and the needle tip was dried. Finally, the sample solution was slowly injected into the injection port. Data was acquired after the reading stabilized.

[0212] 2. Positive electrode slurry performance testing

[0213] (1) Solid content of slurry

[0214] Weigh the copper foil in the weight loss rate measuring instrument and record the weight as M0, then zero the instrument.

[0215] Take a small amount of positive electrode slurry, coat it onto copper foil, and then weigh it in a moisture analyzer, recording it as M1; close the equipment and start drying; after the drying is completed, record the weighing data as M2, and calculate the solid content, which is (M2-M0) / (M1-M0).

[0216] (2) Slurry stability test

[0217] After re-stirring the slurry for 30 minutes, take a certain amount of slurry and pour it into the sample bottle of the stability tester. After placing the sample bottle, close the test tower lid and open the test tower lid. The test interface will start to show the scanning curve, and the sample stability test will begin. The test will continue for more than 72 hours to complete the test.

[0218] (3) Slurry viscosity

[0219] Use a rotational viscometer, model DV-2TLV, from Bollerfeld. When using it, select the appropriate rotor according to the viscosity of the slurry, and adjust the parameter to 12 r / min. After the measurement starts, pay attention to the reading on the screen. When the number no longer jumps significantly and the measurement progress on the right rises from the bottom to the top, record the data.

[0220] 3. Battery performance test

[0221] (1) Brittleness test of positive electrode sheet

[0222] Take a defect-free positive electrode sheet and cut it longitudinally into samples with a length and width of 20cm and a width of 2.5cm. The number of samples should be at least 8. First, pre-fold the sample in half. Then, place the sample on the testing platform and roll it once with a 2kg cylindrical roller. If light is transmitted, the number of folds is counted as one. If light is not transmitted, repeat the reverse folding and rolling process. Observe the crease against the light to check for light transmission or breakage. Record the actual number of folds and take the average as the test result.

[0223] (2) Diaphragm resistance

[0224] Cut the dried positive electrode slurry (film layer) into small round pieces with a diameter of 3mm from the left, center, and right sides of the positive electrode sheet. Turn on the power of the Yuaneng Technology electrode resistance meter, place the probe at the appropriate position on the meter, and click the "Start" button. Wait for the reading to stabilize and then take the reading. Test two positions for each small round piece, and finally calculate the average of the six measurements, which is the resistance of the electrode film layer.

[0225] (3) First Coulomb efficiency

[0226] At 25°C, the batteries of the above embodiments and comparative examples were charged at a constant current rate of 0.1C to a voltage of 4.3V. The charging capacity at this time was recorded as the first charge capacity of the secondary battery. After resting for 5 minutes, the batteries were discharged at a constant current rate of 0.1C to a voltage of 2.0V and then rested for 5 minutes. This is one charge-discharge cycle. The discharge capacity of this cycle was recorded as the first discharge capacity of the secondary battery, which is the initial capacity of the secondary battery.

[0227] The first-cycle coulombic efficiency (%) of a secondary battery = first-cycle discharge capacity / first-cycle charge capacity × 100%.

[0228] (4) Capacity retention rate during 45℃ cycling

[0229] At 45°C, the batteries in the examples and comparative examples were charged to 3.65V at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 3.65V, left to rest for 10 minutes, and then discharged to 2.5V at 1 / 3C. The resulting capacity was recorded 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 battery capacity retention rate after each cycle was: Pn = Cn / C0 × 100%.

[0230] During this test, the first cycle corresponds to n=1, the second cycle to n=2, ..., the 100th cycle to n=100. The battery capacity retention rate data corresponding to Example 1 in Table 1 is the data measured after 300 cycles under the above test conditions, i.e., the value of P300.

[0231] Table 1. Parameters of the dispersion adhesives in each embodiment and comparative example.

[0232]

[0233] Note: Monomer feed ratio refers to the molar ratio of acrylonitrile monomers, butadiene monomers, and substituted olefin monomers; structural unit percentage refers to the molar percentage of structural unit A, structural unit B, and structural unit C in the cyanopolymer; molecular weight refers to weight-average molecular weight; w refers to 10 4 "Ratio" refers to the proportion of the dispersant binder to the total weight of the positive electrode slurry.

[0234] Table 2 Performance parameters of each embodiment and comparative example

[0235]

[0236] Note: "Electrode brittleness" refers to the number of times the electrode is folded in half to transmit light; "capacity retention rate" refers to the capacity retention rate after 300 cycles at 45℃.

[0237] (III) Analysis of Performance Test Results of Positive Electrode and Battery

[0238] The above performance test results show that, compared with the dispersants in the prior art, the dispersant and binder provided in this application can achieve good dispersion of the positive electrode slurry. When applied to the positive electrode sheet, it makes the positive electrode sheet have good flexibility, which is beneficial to improving the stability of the battery; and reduces the resistance of the positive electrode sheet, which is beneficial to improving the battery's first efficiency and capacity retention rate.

[0239] Furthermore, at least one of the dispersibility of the cathode slurry and the flexibility of the cathode electrode sheet can be adjusted by controlling the monomer feed ratio, polymer molecular weight, and substituent groups on the polymer to obtain a cathode slurry with good dispersibility, a cathode electrode sheet with good flexibility, or both. For example, the cathode slurries in Examples 1, 6, and 7 have good dispersibility and the cathode electrode sheets have good flexibility, while the cathode electrode sheets in Examples 2 and 3 have good flexibility. When the proportion of the dispersant binder to the total weight of the cathode slurry is in the range of 0.03%-2.0%, the performance of the corresponding cathode slurry and cathode electrode sheet is better.

[0240] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A battery, characterized by, The battery comprises a positive electrode sheet, the positive electrode sheet comprises a current collector and a positive material layer arranged on at least one side of the current collector, the positive material layer comprises a positive active material and a dispersion binder, the dispersion binder comprises a cyanopolymer, the cyanopolymer comprises structural unit A derived from acrylonitrile, structural unit B derived from butadiene and structural unit C derived from a substituted olefin; wherein the substituted olefin comprises at least one substituent group R', the R' comprises at least one of alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, carboxyl, ester group, carboxylate, amide group, hydroxyl, alkoxy, amine group or ammonium salt.

2. The battery of claim 1, wherein, In the cyanopolymer, the molar proportion of the structural unit A is 10%-30%, the molar proportion of the structural unit B is 60%-80%, and the molar proportion of the structural unit C is 10%-20%.

3. The battery of claim 1 or 2, wherein the electrolyte is a mixture of the first electrolyte and the second electrolyte. The cyanopolymer further comprises at least one substituent group G, the G comprises any one of carboxylic acid group and its derivative, sulfonic acid group and its derivative, phosphonic acid group and its derivative.

4. The battery of claim 3, wherein the cathode is a lithium cobalt oxide cathode. The G is an end group of the cyanopolymer.

5. The battery of any one of claims 1-4, wherein the cathode comprises a lithium metal oxide. At least part of carbon-carbon double bonds in the cyanopolymer is hydrogenated and reduced to carbon-carbon single bond.

6. The battery of any one of claims 1-5, wherein, The weight average molecular weight of the dispersion binder is 10000-1000000.

7. The battery of claim 6, wherein the cathode comprises a lithium metal oxide. The weight average molecular weight of the dispersion binder is 50000-500000.

8. The battery of any one of claims 1-7, wherein, In the substituent group R', The chemical formula of the carboxyl group is and / or The chemical formula of the ester group is and / or The chemical formula of the hydroxyl group is and / or The formula of the alkoxy group is and / or The chemical formula of the amide group is Wherein, the value of n is 0-12; R1 is selected from any one of alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, polyoxyethylene ether group, polyoxyethylene ether polyoxypropylene ether copolymer group; R2 is selected from any one of H, alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, polyoxyethylene ether group, polyoxyethylene ether polyoxypropylene ether copolymer group.

9. The battery of any one of claims 1-7, wherein the cathode comprises a lithium metal oxide. In the substituent group R', The chemical formula of the carboxylate is A + is and / or The chemical formula of the amide group is and / or The chemical formula of the amine group is and / or The chemical formula of the ammonium salt is Wherein, the value of n is 0-12; R3, R4, R5 are respectively selected from any one of H, alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, polyoxyethylene ether group, polyoxyethylene ether polyoxypropylene ether copolymer group.

10. The battery of claim 8 or 9, wherein The polyoxyethylene ether group is h has a value of 1 to 20; and / or The polyoxyethylene polyoxypropylene copolymer group is k has a value of 1 to 15 and l has a value of 1 to 10.

11. The battery of claim 3 or 4, wherein The chemical formula of the carboxylic acid group and its derivatives is Wherein, the value of m is greater than 1 and less than or equal to 12, and R" is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, aromatic ester group; The alkyl group has the formula The alkyl alcohol has the formula The alkyl hydroxylamine has the formula The fatty ester group has the formula The aromatic ester group has the formula p has a value of 1-12, q has a value of 1-16, and the number of carbon atoms in Ar is no more than 12.

12. The battery of any one of claims 3, 4, 11, wherein The chemical formula of the sulfonic acid group and its derivatives is Wherein, the value of m is greater than 1 and less than or equal to 12, and R" is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, aromatic ester group; The alkyl group has the formula The alkyl alcohol has the formula The alkyl hydroxylamine has the formula The fatty ester group has the formula The aromatic ester group has the formula p has a value of 1-12, q has a value of 1-16, and the number of carbon atoms in Ar is no more than 12.

13. The battery of any one of claims 3, 4, 11, 12, wherein The phosphonic acid groups and derivatives thereof include bis-ester phosphonic acids and derivatives thereof or mono-ester phosphonic acids and derivatives thereof, the bis-ester phosphonic acids and derivatives thereof having the chemical formula The mono-ester phosphonic acids and derivatives thereof have the chemical formula Wherein, R" is selected from any one of H, alkyl, alkyl alcohol, alkyl hydroxylamine, aliphatic ester group, aromatic ester group; The alkyl group has the formula The alkyl alcohol has the formula The alkyl hydroxylamine has the formula The fatty ester group has the formula The aromatic ester group has the formula p has a value of 1-12, q has a value of 1-16, and the number of carbon atoms in Ar is no more than 12.

14. The battery of any one of claims 3-13, wherein, The dispersion binder comprises a structure as shown in formula (1): wherein R is a hybrid structure of a:b is in the range of (1:2)-(1:8), and a:c is in the range of (10:1)-(1:10).

15. The battery of any one of claims 1-14, wherein, the positive active material comprises one or more of lithium iron phosphate, lithium manganese iron phosphate.

16. The battery of any one of claims 1-15, wherein, the positive electrode sheet has a sheet resistance of 0.05 Ω-0.50 Ω.

17. A positive electrode slurry, characterized by, comprises a positive active material, a dispersion binder, and a solvent, the dispersion binder comprises a cyano polymer, the cyano polymer comprises structural unit A derived from acrylonitrile, structural unit B derived from butadiene, and structural unit C derived from a substituted olefin; wherein the substituted olefin comprises at least one substituent group R', the R' comprises at least one of alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, carboxyl, ester group, carboxylate, amide group, hydroxyl, alkoxy, amine group, or ammonium salt.

18. The positive electrode slurry of claim 17, wherein, the dispersion binder accounts for 0.01%-3.0% of the total weight of the positive electrode slurry.

19. The positive electrode slurry of claim 18, wherein, the dispersion binder accounts for 0.03%-2.0% of the total weight of the positive electrode slurry.

20. The positive electrode slurry according to any one of claims 17 to 19, wherein the positive electrode slurry has a viscosity of 4000 mPa·s-30000 mPa·s.

21. The positive electrode paste according to any one of claims 17 to 20, wherein the positive electrode slurry has a solid content of 55%-65%.

22. A dispersion adhesive, characterized by comprises a cyano polymer, the cyano polymer comprises structural unit A derived from acrylonitrile, structural unit B derived from butadiene, and structural unit C derived from a substituted olefin; wherein the substituted olefin comprises at least one substituent group R', the R' comprises at least one of alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, carboxyl, ester group, carboxylate, amide group, hydroxyl, alkoxy, amine group, or ammonium salt.

23. The dispersion adhesive according to claim 22, wherein the cyano polymer further comprises at least one substituent group G, the G comprises any one of carboxylic acid group and its derivatives, sulfonic acid group and its derivatives, phosphonic acid group and its derivatives.

24. A method for producing a dispersion adhesive, characterized by comprises the following steps: providing an acrylonitrile monomer, a butadiene monomer, and a substituted olefin monomer as monomer raw materials; the substituted olefin comprises at least one substituent group R', the R' comprises at least one of alkyl with carbon atom number of 1-18, aryl with carbon atom number of 6-18, carboxyl, ester group, carboxylate, amide group, hydroxyl, alkoxy, amine group, or ammonium salt; mixing the acrylonitrile monomer, the butadiene monomer, and the substituted olefin monomer with an initiator to perform a polymerization reaction, to obtain a cyano polymer.

25. The method for preparing the dispersible adhesive as described in claim 24, characterized in that, the preparation method further comprises: adding an end-capping agent to the polymerization reaction to stop the polymerization, to obtain a hydroxyl polymer, the end-capping agent comprises ethylene oxide; reacting the hydroxyl polymer with a halogen-substituted compound containing a substituent group G, to obtain a cyano polymer containing the substituent group G; the substituent group G comprises any one of carboxylic acid group and its derivatives, sulfonic acid group and its derivatives, phosphonic acid group and its derivatives.

26. The method for preparing the dispersible adhesive as described in claim 24 or 25, characterized in that, the preparation method further comprises: performing a hydrogenation reaction on the cyano polymer or the hydroxyl polymer.

27. The method of claim 24-26, wherein the dispersion adhesive is prepared by, The molar ratio of the acrylonitrile-based monomer to the butadiene-based monomer in the monomer raw material is (1:2)-(1:8), and the molar ratio of the acrylonitrile-based monomer to the substituted olefin-based monomer is (10:1)-(1:10).

28. An electrical device, comprising: The battery as claimed in any one of claims 1 to 15.

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