Dispersant and preparation method thereof, slurry composition, battery and electrical device

Abstract

A dispersant and a preparation method thereof, a slurry composition, an electrode plate, and an electrical device including the electrode plate. The dispersant includes a first polymer and a second polymer, the weight average molecular weight of the first polymer is less than the weight average molecular weight of the second polymer, the first polymer includes structural units I) and II), (I), (II), the second polymer includes structural units III) and IV), (III), (IV), R1, R2, R3, R6, R7, and R8 are independently selected from hydrogen, halogen, carboxyl, amino acid, acyl halide, carbonyl, cyano, anhydride, nitro, nitroso, substituted or unsubstituted amide, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted ester, substituted or unsubstituted sulfonic acid, substituted or unsubstituted C6-C12 aryl, R4, R5, R9, R 10 All have dipole moments greater than 2×10 ‑30 C·m group. The dispersant can improve the dispersion effect of the slurry.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a dispersant and a preparation method thereof, a slurry composition, a battery, and an electrical device. Background Art

[0002] With technological advancements, batteries have found widespread use in power-consuming devices such as mobile phones, tablets, laptops, and electric vehicles. Simultaneously, demands for their performance, such as cycle performance, are becoming increasingly stringent. The dispersion of electrode slurries is crucial to battery cycle performance, and therefore, improving the dispersion of electrode slurries is a pressing issue in battery technology. Summary of the Invention

[0003] The present application provides a dispersant and a preparation method thereof, a slurry composition, a battery and an electrical device. The dispersant can improve the dispersion effect of electrode slurry.

[0004] In a first aspect, an embodiment of the present application provides a dispersant comprising a first polymer and a second polymer, wherein the weight average molecular weight of the first polymer is less than the weight average molecular weight of the second polymer;

[0005] The first polymer comprises a first structural unit having formula I) and a second structural unit having formula II);

[0006]

[0007] wherein R1, R2 and R3 are independently selected from the following groups: hydrogen, halogen, carboxyl, amino acid, acyl halide, carbonyl, cyano, anhydride, nitro, nitroso, substituted or unsubstituted C2-C15 amide, substituted or unsubstituted C2-C15 alkenyl, substituted or unsubstituted C3-C15 alkynyl, substituted or unsubstituted C2-C15 ester, substituted or unsubstituted C2-C15 sulfonic acid, substituted or unsubstituted C6-C12 aryl, and R4 and R5 both have a dipole moment greater than 2×10 -30 C·m group; a is the number of the first structural unit, b is the number of the second structural unit;

[0008] The second polymer comprises a third structural unit having formula III) and a fourth structural unit having formula IV);

[0009]

[0010] The dispersant provided in the embodiment of the present application comprises a first polymer and a second polymer, wherein the weight average molecular weight of the first polymer is less than the weight average molecular weight of the second polymer, so that the first polymer can diffuse between the particles. The first polymer comprises a first structural unit having formula I) and a second structural unit having formula II), which can help the particles to be quickly wetted and dispersed. The second polymer comprises a third structural unit having formula III) and a fourth structural unit having formula IV), which can synergize with the first polymer to reduce the agglomeration between the particles and accelerate the dispersion of the particles, thereby improving the dispersion effect of the electrode slurry while also increasing the solid content in the electrode slurry, thereby facilitating the improvement of the cycle performance of the battery.

[0011] In some embodiments of the present application, the dipole moments of R4 and R5 are respectively less than 2×10 -30 C·m, and R4 and R5 contain dipole moments greater than 2×10 -30 C·m group. R9 and R 10 The dipole moment is less than 2×10 -30 C·m, and R9 and R 10 Contains dipole moments greater than 2×10 -30 C·m group, which can further reduce the agglomeration between particles in the electrode slurry and make the electrode slurry evenly dispersed.

[0012] In some embodiments of the present application, R4, R5, R9 and R 10 The dipole moment is greater than 2×10 -30 C·m, which can further accelerate the dispersion of the electrode slurry and shorten the preparation time of the electrode slurry.

[0013] In some embodiments of the present application, R4 and R5 are independently selected from the following groups: hydroxyl, carboxyl, pyrrolidone, ethylene oxide, propylene oxide. And / or, R9 and R 10 Each of the following groups is independently selected from the group consisting of hydroxyl, carboxyl, pyrrolidone, ethylene oxide, and propylene oxide.

[0014] In some embodiments of the present application, R1, R2, and R3 are independently selected from the following groups: hydrogen, unsubstituted amide, or benzene, and R4 and R5 are independently selected from the following groups: carboxyl or pyrrolidone. R1, R2, R3, R4, and R5 are selected from the above groups to facilitate diffusion of the first polymer between the particles, thereby facilitating wetting and dispersion of the particles.

[0015] In some embodiments of the present application, the first structural unit has the following structural formula:

[0016]

[0017] The second structural unit has the following structural formula:

[0018]

[0019] In some embodiments of the present application, R6, R7 and R8 are independently selected from the following groups: hydrogen, amide or benzene, R9 and R 10 are independently selected from the following groups: carboxyl or pyrrolidone.

[0020] In some embodiments of the present application, the third structural unit has the following structural formula:

[0021]

[0022] The fourth structural unit has the following structural formula:

[0023]

[0024] In some embodiments of the present application, the value range of a is 1-15, the value range of b is 1-15, the value range of c is 1-200, and the value range of d is 1-200. When the number a of the first structural units, the number b of the second structural units, the number c of the third structural units, and the number d of the fourth structural units are within appropriate ranges, the first polymer and the second polymer can better exert a synergistic effect, further reduce agglomeration between particles, and accelerate the dispersion of particles, thereby further improving the dispersion effect of the electrode slurry.

[0025] In some embodiments of the present application, the weight average molecular weight of the first polymer is less than 1000. The weight average molecular weight of the first polymer is set within the above appropriate range, so that the first polymer can easily diffuse into the gaps between particles and can also be adsorbed on the surface of particles to accelerate the dispersion of particles.

[0026] In some embodiments of the present application, the weight average molecular weight of the second polymer is in the range of 1000-500000. The weight average molecular weight of the second polymer is set within the above suitable range so that it is adsorbed on the surface of the particles to further reduce the agglomeration between the particles.

[0027] In some embodiments of the present application, the mass ratio of the first polymer to the second polymer is (0.1-10): 1. Setting the mass ratio of the first polymer to the second polymer within the above range enables the first polymer and the second polymer to work together better to accelerate particle dispersion while reducing agglomeration between particles, thereby increasing the solid content of the electrode slurry and reducing the resistance of the electrode sheet using the electrode slurry, thereby improving the cycle performance of the battery.

[0028] In a second aspect, an embodiment of the present application provides a method for preparing the dispersant as described in any of the above embodiments, comprising:

[0029] Preparation of the first polymer: dissolving an initiator, a chain transfer agent, and a monomer of the first structural unit in an organic solvent and reacting with stirring under an inert atmosphere to obtain a solution containing the first structural unit; adding a monomer of the second structural unit to the solution containing the first structural unit to react; after the reaction is completed, precipitating, filtering, and drying the resulting product to obtain the first polymer;

[0030] Preparation of the second polymer: dissolving an initiator, a chain transfer agent, and a monomer of the third structural unit in an organic solvent and reacting with stirring under an inert atmosphere to obtain a solution containing the third structural unit; adding the monomer of the second structural unit to the solution containing the third structural unit to react; after the reaction is completed, precipitating, filtering, and drying the resulting product to obtain the second polymer;

[0031] The first polymer and the second polymer are mixed to obtain the dispersant.

[0032] The preparation method provided in the embodiments of the present application is simple and safe. The prepared dispersant can help to evenly disperse the particles in the electrode slurry, increase the solid content in the electrode slurry, and thus improve the cycle performance of the battery.

[0033] In some embodiments of the present application, the stirring linear speed of the stirring reaction is 2 m / s-8 m / s, and the total stirring time is 120 min-200 min.

[0034] Thirdly, embodiments of the present application provide a slurry composition for forming an electrode film layer. The slurry composition, calculated as 100% by mass, comprises: a dispersant (0.01%-5%); a binder (0.5%-10%); an active material (89%-93.99%); and a conductive agent (0.01%-5%). By properly selecting the content of each component, the dispersion effect of the slurry can be further improved, and the solid content in the slurry can also be increased, thereby enhancing the battery's cycling performance.

[0035] In some embodiments of the present application, the active material is a positive electrode active material. The dispersant can be better adsorbed on the surface of the positive electrode active material to make it evenly dispersed, thereby further improving the cycle performance of the battery.

[0036] In a fourth aspect, an embodiment of the present application provides a battery cell, comprising:

[0037] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector;

[0038] A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector;

[0039] A diaphragm, provided between the positive electrode sheet and the negative electrode sheet;

[0040] Wherein, the positive electrode active material layer and / or the negative electrode active material layer are made using the slurry composition described in the above embodiment.

[0041] In a fifth aspect, an embodiment of the present application provides a battery, comprising the battery cell described in the above embodiment.

[0042] In a sixth aspect, an embodiment of the present application provides an electrical device, comprising the battery described in the above embodiment, wherein the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without any creative work.

[0044] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application is shown;

[0045] Figure 2 shows a schematic structural diagram of a battery pack provided in some embodiments of the present application;

[0046] Figure 3 Shown Figure 2 Schematic diagram of the exploded structure of the battery;

[0047] Figure 4 shows a schematic structural diagram of a battery cell provided by some embodiments of the present application;

[0048] Figure 5 Shown Figure 4 Schematic diagram of the exploded structure of a battery cell.

[0049] In the drawings, the drawings are not drawn to scale.

[0050] Marking Description:

[0051] Vehicles 1000;

[0052] Battery 100, controller 200, motor 300;

[0053] Box 10, first box 11, second box 12;

[0054] Battery cell 20 , housing 21 , electrode assembly 22 , cover assembly 23 . DETAILED DESCRIPTION

[0055] The following embodiments of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

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

[0058] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0059] In the description of the embodiments of the present application, unless otherwise specified, "above" and "below" are inclusive of the number, and "a variety" and "multiple" in "one or more" and "one or more" mean more than two (or more).

[0060] In the description of the embodiments of the present application, the terms "a" and "the" refer to one or more molecules of the compound, rather than being limited to a single molecule of the compound. In addition, the one or more molecules may be the same or different, as long as they fall within the scope of the chemical compound.

[0061] The grouping of alternative elements or embodiments disclosed herein should not be construed as limiting. Each group member may be adopted and claimed individually, or adopted and claimed in any combination with other members of the group or other elements found herein. It is anticipated that, for convenience and / or patentability reasons, one or more members of a group may be included in or deleted from the group. When any such inclusion or deletion occurs, the specification is deemed herein to contain the modified group, thus satisfying the written description of all Markush groups used in the claims.

[0062] It will be apparent to those skilled in the art that various modifications and variations can be made in this application without departing from the scope of protection of this application. Therefore, this application is intended to cover modifications and variations of this application that fall within the scope of the corresponding claims (scopes for which protection is sought) and their equivalents. It should be noted that the embodiments provided in the examples of this application can be combined with each other unless there is any contradiction.

[0063] Before explaining the scope of protection provided by the embodiments of the present application, in order to facilitate understanding of the embodiments of the present application, the present application first specifically describes the problems existing in the related technology.

[0064] The dispersion of electrode slurries is crucial to battery cycling performance. Currently, wetting and dispersing agents are often added to slurries, or the stirring process is optimized to improve the dispersion of solid components in organic solvents. The inventors have found through experimental research that these dispersants and optimized stirring processes have limited effects on slurry dispersion, resulting in battery cycling performance that fails to meet expectations.

[0065] In view of this, the present application provides a dispersant and a preparation method thereof, a slurry composition, an electrode plate and an electrical device including the electrode plate, which can improve the dispersion effect of the slurry.

[0066] In the present application, an electric device may include, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. Among them, an electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and a spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0067] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0068] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application is shown.

[0069] like Figure 1As shown, the vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and operating power requirements of the vehicle 1000 during driving.

[0070] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000 , but also as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .

[0071] Figure 2 A schematic structural diagram of a battery provided in some embodiments of the present application is shown. Figure 3 Shown Figure 2 Schematic diagram of the exploded structure of the battery.

[0072] The battery 100 in this application refers to a battery comprising at least one battery cell 20. Figure 2 and Figure 3 As shown, the battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0073] The housing 10 is used to provide a storage space for the battery cells 20, and the housing 10 can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 cover each other, and the first housing 11 and the second housing 12 jointly define a storage space for accommodating the battery cells 20. The second housing 12 can be a hollow structure with one end open, and the first housing 11 can be a plate-shaped structure. The first housing 11 covers the open side of the second housing 12, so that the first housing 11 and the second housing 12 jointly define a storage space; the first housing 11 and the second housing 12 can also be hollow structures with one side open, and the open side of the first housing 11 covers the open side of the second housing 12. Of course, the housing 10 formed by the first housing 11 and the second housing 12 can be of various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0074] In the battery 100, there may be multiple battery cells 20. The multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10.

[0075] Each battery cell 20 may be a secondary battery cell or a primary battery cell, such as a lithium-ion secondary battery cell, a sodium-ion secondary battery cell, a magnesium-ion secondary battery cell, or a potassium-ion secondary battery cell, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or have other shapes.

[0076] Figure 4 A schematic structural diagram of a battery cell provided in some embodiments of the present application is shown. Figure 5 Shown Figure 4 Schematic diagram of the exploded structure of a battery cell.

[0077] The battery cell 20 is the smallest unit that makes up the battery 100. Figure 4 and Figure 5 As shown, the battery cell 20 includes a housing 21, an electrode assembly 22, and a cover assembly 23. The housing 21 has a chamber for accommodating the electrode assembly 22, and the cover assembly 23 is used to close the opening of the housing 21. The cover assembly 23 includes an end cap, which is connected to the housing 21 to form the outer shell of the battery cell 20. The electrode assembly 22 is disposed within the housing 21, and the housing 21 is filled with electrolyte.

[0078] The end cap refers to a component that covers the opening of the shell 21 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap can be adapted to the shape of the shell 21 to match the shell 21. Optionally, the end cap can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap is not easily deformed when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved safety performance. Functional components such as electrode terminals can be provided on the end cap. The electrode terminal can be used to electrically connect to the electrode assembly 22 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap to isolate the electrical connection components in the housing 21 from the end cap to reduce the risk of short circuit.

[0079] The shell 21 is a component used to cooperate with the end cap to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, electrolyte and other components. The shell 21 and the end cap can be independent components. An opening can be set on the shell 21, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap. Without limitation, the end cap and the shell 21 can also be integrated. Specifically, the end cap and the shell 21 can form a common connection surface before other components are inserted into the shell. When the interior of the shell 21 needs to be encapsulated, the end cap is covered with the shell 21. The shell 21 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc.

[0080] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be contained in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly 22, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0081] dispersants

[0082] The embodiment of the present application provides a dispersant, comprising a first polymer and a second polymer, wherein the weight average molecular weight of the first polymer is less than the weight average molecular weight of the second polymer;

[0083] The first polymer comprises a first structural unit having formula I) and a second structural unit having formula II);

[0084]

[0085]

[0086] wherein R1, R2 and R3 are independently selected from the following groups: hydrogen, halogen, carboxyl, amino acid, acyl halide, carbonyl, cyano, anhydride, nitro, nitroso, substituted or unsubstituted C2-C15 amide, substituted or unsubstituted C2-C15 alkenyl, substituted or unsubstituted C3-C15 alkynyl, substituted or unsubstituted C2-C15 ester, substituted or unsubstituted C2-C15 sulfonic acid, substituted or unsubstituted C6-C12 aryl, and R4 and R5 both have a dipole moment greater than 2×10 -30 C·m group; a is the number of the first structural unit, b is the number of the second structural unit;

[0087] The second polymer comprises a third structural unit having formula III) and a fourth structural unit having formula IV);

[0088]

[0089] wherein R6, R7 and R8 are independently selected from the following groups: hydrogen, halogen, carboxyl, amino acid, acyl halide, carbonyl, cyano, anhydride, nitro, nitroso, substituted or unsubstituted amide, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted ester, substituted or unsubstituted sulfonic acid, substituted or unsubstituted C6-C12 aryl, R9 and R 10 All have dipole moments greater than 2×10 -30 C·m group; c is the number of the third structural unit, d is the number of the fourth structural unit.

[0090] In the present application, halogen refers to fluorine, chlorine, bromine or iodine.

[0091] In this application, when a compound or chemical structure feature (e.g., alkyl, aryl) is referred to as being "substituted," the feature may have one or more substituents. The term "substituent" has the broadest meaning known to those of ordinary skill in the art and includes moieties that occupy the position normally occupied by one or more hydrogen atoms attached to the parent compound or chemical structure feature.

[0092] In this application, the term "aryl" refers to a closed aromatic ring or ring system. Examples of aryl include, but are not limited to, phenyl, naphthyl, phenanthrenyl, anthracenyl, biphenyl (including diphenyl and terphenyl), triphenylene, pyrenyl, spirobifluorenyl, 1-HEXANYL, 1-HYDROXY-1-CARBOXY ...

[0093] The dispersant provided in the embodiment of the present application comprises a first polymer and a second polymer, wherein the weight average molecular weight of the first polymer is less than the weight average molecular weight of the second polymer, so that the first polymer can diffuse between the particles. The first polymer comprises a first structural unit having formula I) and a second structural unit having formula II), which can help the particles to be quickly wetted and dispersed. The second polymer comprises a third structural unit having formula III) and a fourth structural unit having formula IV), which can synergize with the first polymer to reduce the agglomeration between the particles and accelerate the dispersion of the particles, thereby improving the dispersion effect of the electrode slurry while also increasing the solid content in the electrode slurry, thereby facilitating the improvement of the cycle performance of the battery.

[0094] In some embodiments of the present application, the dipole moments of R4 and R5 are respectively less than 2×10 -30C·m, and R4 and R5 contain dipole moments greater than 2×10 -30 C·m group. R9 and R 10 The dipole moment is less than 2×10 -30 C·m, and R9 and R 10 Contains dipole moments greater than 2×10 -30 C·m group, which can further reduce the agglomeration between particles in the electrode slurry and make the electrode slurry evenly dispersed.

[0095] In some embodiments of the present application, R4, R5, R9 and R 10 The dipole moment is greater than 2×10 -30 C·m, which can further accelerate the dispersion of the electrode slurry and shorten the preparation time of the electrode slurry.

[0096] In some examples, the non-polar group can be any of the linear, branched and cyclic groups, such as non-polar functional groups or hydrocarbon groups. These groups have excellent non-polarity, can reduce the agglomeration between particles, and improve the dispersion effect of the electrode slurry.

[0097] In some embodiments of the present application, R4 and R5 are independently selected from the following groups: hydroxyl, carboxyl, pyrrolidone, ethylene oxide, and propylene oxide.

[0098] In some embodiments of the present application, R9 and R 10 Each of the following groups is independently selected from the group consisting of hydroxyl, carboxyl, pyrrolidone, ethylene oxide, and propylene oxide.

[0099] In some embodiments of the present application, R1, R2 and R3 are independently selected from the following groups: hydrogen, unsubstituted amide or benzene, and R4 and R5 are independently selected from the following groups: carboxyl or pyrrolidone.

[0100] In the above embodiments, R1, R2, R3, R4 and R5 are respectively selected from the above groups, which can make the first polymer easily diffuse between the particles to facilitate the wetting and dispersion of the particles.

[0101] In some embodiments of the present application, the first structural unit has the following structural formula:

[0102]

[0103] The second structural unit has the following structural formula:

[0104]

[0105] In some embodiments of the present application, R6, R7 and R8 are independently selected from the following groups: hydrogen, amide or benzene, R9 and R 10are independently selected from the following groups: carboxyl or pyrrolidone.

[0106] In the above embodiments, R6, R7, R8, R9 and R 10 Respectively selected from the above groups can further reduce the agglomeration between particles and accelerate the dispersion of particles.

[0107] In some embodiments of the present application, the third structural unit has the following structural formula:

[0108]

[0109] The fourth structural unit has the following structural formula:

[0110]

[0111] In some embodiments of the present application, the value range of a is 1-15, the value range of b is 1-15, the value range of c is 1-200, and the value range of d is 1-200. When the number a of the first structural units, the number b of the second structural units, the number c of the third structural units, and the number d of the fourth structural units are within appropriate ranges, the first polymer and the second polymer can better exert a synergistic effect, further reduce agglomeration between particles, and accelerate the dispersion of particles, thereby further improving the dispersion effect of the electrode slurry.

[0112] In some embodiments of the present application, the weight average molecular weight of the first polymer is less than 1,000.

[0113] In the above embodiments, the weight average molecular weight of the first polymer is set within the above appropriate range, so that the first polymer can be easily diffused into the gaps between the particles and can also be adsorbed on the surface of the particles to accelerate the dispersion of the particles.

[0114] In some examples, the weight average molecular weight of the first polymer can be, but is not limited to, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, or 1000.

[0115] In some embodiments of the present application, the weight average molecular weight of the second polymer is in the range of 1,000-500,000.

[0116] In the above embodiments, the weight average molecular weight of the second polymer is set within the above appropriate range so that it is adsorbed on the surface of the particles to further reduce the agglomeration between the particles.

[0117] In some examples, the weight average molecular weight of the second polymer can be, but is not limited to, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 or more.

[0118] In some embodiments of the present application, the mass ratio of the first polymer to the second polymer is (0.1-10):1.

[0119] In the above embodiments, the mass ratio of the first polymer to the second polymer is set within the above range, which enables the first polymer and the second polymer to work together better to accelerate particle dispersion while reducing agglomeration between particles, thereby increasing the solid content of the electrode slurry and reducing the resistance of the electrode plate using the electrode slurry, thereby improving the cycle performance of the battery.

[0120] Preparation method of dispersant

[0121] The present application provides a method for preparing a dispersant as in any of the above embodiments, comprising:

[0122] S10, preparation of the first polymer:

[0123] S11: dissolving an initiator, a chain transfer agent, and a monomer of the first structural unit in an organic solvent, and stirring the mixture under an inert atmosphere to react to obtain a solution containing the first structural unit;

[0124] S12: adding a monomer of the second structural unit to the solution containing the first structural unit to react;

[0125] S13: After the reaction is completed, the obtained product is precipitated, filtered and dried to obtain a first polymer.

[0126] S20, preparation of the second polymer:

[0127] S21: dissolving an initiator, a chain transfer agent, and a monomer of the third structural unit in an organic solvent, and stirring the mixture under an inert atmosphere to react to obtain a solution containing the third structural unit;

[0128] S22: adding a monomer of the fourth structural unit to the solution containing the third structural unit to react;

[0129] S23: After the reaction is completed, the obtained product is precipitated, filtered and dried to obtain a second polymer.

[0130] S30: Preparation of a dispersant: mixing the first polymer and the second polymer to obtain the dispersant.

[0131] The preparation method provided in the embodiments of the present application is simple and safe. The prepared dispersant can help to evenly disperse the particles in the electrode slurry, increase the solid content in the electrode slurry, and thus improve the cycle performance of the battery.

[0132] In some embodiments of the present application, the linear speed of stirring in steps S11 and S21 is in the range of 4 m / s-8 m / s.

[0133] In the above embodiments, the stirring linear velocity is within the above range, which can help the initiator and the chain transfer agent dissolve in the solvent and facilitate the reaction.

[0134] In some embodiments of the present application, the reaction temperature of the reactions in steps S11, S12, S21 and S22 is 40°C-80°C, the stirring linear speed of the stirring reaction is also 2m / s-8m / s, and the total stirring time is 120min-200min.

[0135] In the above embodiments, the reaction temperature is within the above range, which can increase the yield of the product in the reaction.

[0136] In some embodiments of the present application, the initiator can be any one or more initiators used for copolymerization, such as azo compounds. For example, the initiator can be, but is not limited to, azobisisobutyronitrile (AIBN).

[0137] In some embodiments of the present application, the chain transfer agent can be any one or more chain transfer agents used in copolymerization reactions, and the present application does not impose specific limitations on this. For example, the chain transfer agent can have a structural formula of Formula V):

[0138]

[0139] Among them, R 11 An alkyl group selected from C1-C5.

[0140] Slurry composition for forming electrode film layer

[0141] An embodiment of the present application provides a slurry composition for forming an electrode film layer, comprising the dispersant in any of the above embodiments as well as a binder, an active material, and an optional conductive agent.

[0142] In the slurry composition provided in the embodiments of the present application, since it contains the dispersant in any of the above embodiments, the slurry composition has a higher solid content and can form an electrode film layer on the surface of the electrode plate so that the electrode plate has a lower resistance, thereby improving the cycle performance of the battery.

[0143] In some embodiments of the present application, the binder may include but is not limited to at least one of sodium polyacrylate, polyacrylamide, polyacrylic acid, polyacrylate, polyacrylonitrile, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl alcohol.

[0144] In some embodiments of the present application, the conductive agent may include but is not limited to at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0145] In some embodiments of the present application, the slurry composition comprises, based on a total mass fraction of 100%, the following: dispersant, 0.01%-5%; binder, 0.5%-10%; active material, 89%-93.99%; conductive agent, 0.01%-5%.

[0146] In the above embodiments, by reasonably selecting the content of each component, the dispersion effect of the slurry can be further improved, and the solid content in the slurry can also be increased, thereby improving the cycle performance of the battery.

[0147] In some embodiments of the present application, the active material is a positive electrode active material.

[0148] In the above embodiments, the dispersant can be better adsorbed on the surface of the positive electrode active material, making it evenly dispersed, thereby further improving the cycle performance of the battery.

[0149] Exemplarily, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional 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 may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0150] In other embodiments of the present application, the active material may also be a negative electrode active material, and the negative electrode active material may be any one or more negative electrode active materials used in batteries.

[0151] Exemplarily, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0152] Electrode plate

[0153] An embodiment of the present application provides an electrode plate, comprising a current collector and an active material layer, wherein the active material layer is disposed on at least one surface of the current collector, and the active material layer is formed using the slurry composition of any of the above embodiments.

[0154] In the above embodiments, since the active material layer of the electrode sheet is formed using the slurry composition in any of the above embodiments, the electrode sheet has a lower resistance, thereby improving the cycle performance of the battery.

[0155] In some embodiments of the present application, the current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0156] battery cells

[0157] The present embodiment provides a battery cell comprising a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and / or the negative electrode sheet are the electrode sheets described in the above embodiment.

[0158] In the above embodiment, since the positive electrode plate and / or the negative electrode plate are the electrode plates in the above embodiment, the battery has good cycle performance.

[0159] In some embodiments of the present application, the positive electrode sheet is the electrode sheet described in the above embodiments, and the active material layer is a positive electrode active material layer. The positive electrode sheet can be prepared by the following method: applying the above-mentioned positive electrode slurry composition on at least one surface of a positive electrode current collector, drying, and cold pressing to obtain a positive electrode sheet.

[0160] In some embodiments of the present application, the negative electrode sheet is the electrode sheet described in the above embodiments, and the active material layer is a negative electrode active material layer. The negative electrode sheet can be prepared by the following method: applying the above-mentioned negative electrode slurry composition on at least one surface of a negative electrode current collector, drying, and cold pressing to obtain the negative electrode sheet.

[0161] The present application has no particular limitation on the type of the diaphragm, and any one or more porous structure diaphragms with good chemical stability and mechanical stability may be used.

[0162] In some embodiments of the present application, the material of the separator can be selected from at least one of glass fiber, non-woven 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.

[0163] In embodiments of the present application, an electrolyte is also included, which acts as an ion conductor between the positive electrode and the negative electrode. The present application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. For example, the electrolyte can be liquid, gel, or fully solid.

[0164] In some embodiments of the present application, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0165] In some embodiments of the present application, the electrolyte salt can 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.

[0166] In some embodiments of the present application, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, ethylene carbonate, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0167] In some embodiments of the present application, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0168] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, to obtain an electrode assembly, or the electrode assembly can be obtained after winding; the electrode tabs are connected to the electrode assembly, and the electrode assembly is placed in a packaging shell, and then heated to remove excess water, and then the electrolyte is injected and sealed; finally, after standing, hot and cold pressing, formation, shaping, capacity testing and other processes, the secondary battery of the present application is obtained.

[0169] Battery

[0170] The present application provides a battery comprising the battery cell of the above embodiment. Since the battery cell of the above embodiment is included, the battery also has the technical effects of the above battery cell, which will not be described in detail here.

[0171] Electrical devices

[0172] An embodiment of the present application provides an electrical device, comprising the battery in the above embodiment, wherein the battery is used to provide electrical energy.

[0173] The dispersant and its preparation method, the slurry composition and the battery cell are described in detail below through specific examples.

[0174] Example 1

[0175] Preparation of dispersant

[0176] The specific preparation steps of the dispersant are as follows:

[0177] (1) Preparation of the first polymer:

[0178] 0.05 mol of initiator AIBN, 0.06 mol of RAFT agent, 0.2 mol of ethylene monomer, 0.1 mol of acrylamide monomer, and 0.1 mol of styrene monomer were dissolved in 500 mL of dioxane to obtain a mixed solution. Nitrogen was introduced into the mixed solution, and the temperature was controlled at 60° C. The mixture was stirred and reacted for 6 hours to obtain a solution containing the first structural unit.

[0179] adding 0.25 mol of acrylic acid monomer and 0.25 mol of vinyl pyrrolidone monomer to the solution containing the first structural unit and reacting for 6 hours to form the second structural unit and polymerize the first structural unit and the second structural unit;

[0180] After the reaction is completed, the obtained product is precipitated, filtered, and dried to obtain a first polymer. The weight average molecular weight of the first polymer is about 800.

[0181] (2) Preparation of the second polymer:

[0182] 0.05 mol of initiator AIBN, 0.06 mol of RAFT agent, 2 mol of ethylene monomer, 1 mol of acrylamide monomer, and 1 mol of styrene monomer were dissolved in 5 L of dioxane to obtain a mixed solution. Nitrogen was introduced into the mixed solution, and the temperature was controlled at 60° C. The mixture was stirred and reacted for 6 hours to obtain a solution containing the third structural unit.

[0183] 2.5 mol of acrylic acid monomer and 2.5 mol of vinyl pyrrolidone monomer are added to the solution containing the third structural unit, and the mixture is reacted for 6 hours to form a fourth structural unit and polymerize the third structural unit and the fourth structural unit;

[0184] After the reaction is completed, the obtained product is precipitated, filtered, and dried to obtain a second polymer. The weight average molecular weight of the second polymer is about 8,000.

[0185] (3) The first polymer and the second polymer were mixed in a mass ratio of 1:1 to prepare a dispersant, which was recorded as dispersant 1.

[0186] Preparation of positive electrode

[0187] The specific steps for preparing the positive electrode are as follows:

[0188] (1) stirring and mixing the carbon nanotubes, the dispersant, and the N-methylpyrrolidone solvent to obtain a first mixture, wherein the stirring linear velocity is 6 m / s and the stirring time is 30 min;

[0189] (2) adding PVDF to the first mixture and stirring and mixing to obtain a second mixture, wherein the stirring linear speed is 6 m / s and the stirring time is 30 min;

[0190] (3) adding the lithium iron phosphate agent to the second mixture and stirring and mixing to obtain a positive electrode slurry, wherein the stirring linear speed is 6 m / s and the stirring time is 30 min;

[0191] (4) coating the positive electrode slurry on the surface of the aluminum foil, drying and cold pressing to obtain a positive electrode sheet;

[0192] The weight ratio of the lithium iron phosphate, carbon nanotubes, PVDF and dispersant is 93.5:4:2:0.5.

[0193] Preparation of negative electrode sheet

[0194] The specific steps for preparing the negative electrode are as follows:

[0195] (1) artificial graphite / silicon dioxide, Super P, polytetrafluoroethylene (PVDF), and a dispersant are thoroughly stirred and mixed in a deionized water solvent system at a weight ratio of 96:2:1:1 to obtain a negative electrode slurry;

[0196] (2) The negative electrode slurry is coated on the copper foil, and after drying and cold pressing, the negative electrode sheet is obtained.

[0197] Preparation of electrolyte

[0198] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7 to obtain an organic solvent. 12.5% ​​lithium hexafluorophosphate (LiPF6) was added and dissolved in the above organic solvent, and stirred evenly to obtain an electrolyte.

[0199] diaphragm

[0200] A polyethylene film was used as the separator.

[0201] Preparation of battery cells

[0202] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator being placed between the positive and negative electrode sheets to serve as an isolation device. The electrode assembly is then wound, and the electrode assembly is welded with tabs. The electrode assembly is then placed in an aluminum shell and baked at 80°C to remove moisture. The electrolyte is then injected and sealed. Finally, the battery cell of this embodiment is obtained through processes such as standing, hot and cold pressing, formation, and shaping.

[0203] Example 2 and Comparative Examples 1-3

[0204] The preparation methods of the battery monomers of Example 2 and Comparative Examples 1-3 are similar to that of Example 1, except for the dispersant, as shown in Table 1.

[0205] Wherein, the preparation of dispersant 2 of Example 2 is as follows:

[0206] (1) Preparation of the first polymer:

[0207] 0.05 mol of initiator AIBN, 0.06 mol of RAFT agent, 0.2 mol of ethylene monomer, 0.1 mol of ethyl acrylate monomer, and 0.1 mol of styrene monomer were dissolved in 500 mL of dioxane to obtain a mixed solution. Nitrogen was introduced into the mixed solution, and the temperature was controlled at 60° C. The mixture was stirred and reacted for 6 hours to obtain a solution containing the first structural unit.

[0208] adding 0.25 mol of acrylic acid monomer and 0.25 mol of vinyl pyrrolidone monomer to the solution containing the first structural unit and reacting for 6 hours to form the second structural unit and polymerize the first structural unit and the second structural unit;

[0209] After the reaction is completed, the obtained product is precipitated, filtered, and dried to obtain a first polymer. The weight average molecular weight of the first polymer is about 800.

[0210] (2) Preparation of the second polymer:

[0211] 0.05 mol of initiator AIBN, 0.06 mol of RAFT agent, 2 mol of ethylene monomer, 1 mol of ethyl acrylate monomer, and 1 mol of styrene monomer were dissolved in 5 L of dioxane to obtain a mixed solution. Nitrogen was introduced into the mixed solution, and the temperature was controlled at 60° C. The mixture was stirred and reacted for 6 hours to obtain a solution containing the third structural unit.

[0212] 2.5 mol of acrylic acid monomer and 2.5 mol of vinyl pyrrolidone monomer were added to the solution containing the third structural unit, and the reaction was carried out for 6 hours to form a fourth repeating structural unit and polymerize the third structural unit and the fourth structural unit;

[0213] After the reaction is completed, the obtained product is precipitated, filtered, and dried to obtain a second polymer. The weight average molecular weight of the second polymer is about 8,000.

[0214] Examples 3 to 7

[0215] The preparation method is similar to that of Example 1, except that the Mw of the first polymer and the second polymer are shown in Table 2.

[0216] Example 8 to Example 12

[0217] The preparation method is similar to that of Example 1, except that the mass ratio of the first polymer to the second polymer is as shown in Table 3.

[0218] Example 13 to Example 30

[0219] The preparation method is similar to that of Example 1, except that the ingredients and contents of the slurry composition are shown in Table 4.

[0220] Test section

[0221] (1) Test of solid content in positive electrode slurry

[0222] The positive electrode slurry is coated on aluminum foil and dried to obtain a positive electrode sheet. The calculation formula for the solid content W of the positive electrode slurry is as follows:

[0223] W=(m1-m0) / (m2-m0)×100%

[0224] Among them, m0 is the mass of the aluminum foil, m1 is the mass of the positive electrode sheet after drying, and m2 is the mass of the wet positive electrode sheet obtained after the positive electrode slurry is coated on the aluminum foil.

[0225] (2) Resistivity test of positive electrode

[0226] The resistivity of the film was directly measured using a Lattice Electronics ST2263 dual-electric digital four-probe tester.

[0227] (3) Test of battery cell capacity retention rate

[0228] In an environment of 25°C, charge the battery cell at a constant current of 1C to 3.65V, then discharge it at a constant current of 0.5C to 2.5V. The measured discharge capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery and record the discharge capacity C0 of the battery after n cycles. n , battery capacity retention rate P after n cycles n =100%×C n / C0. The first cycle corresponds to n=1, the second cycle corresponds to n=2, and the 100th cycle corresponds to n=100. The battery capacity retention rate after 1000 cycles was measured, and the test results are shown in Table 1.

[0229] Table 1 lists the different dispersants and related test results in Examples 1-2 and Comparative Examples 1-3, respectively.

[0230] Table 1

[0231] Serial number dispersants Solid content (%) <![CDATA[Resistivity (10 2 Ω·cm)]]> Capacity retention rate (%) Example 1 Dispersant 1 66.50 0.20 92.4 Example 2 Dispersant 2 64.5％ 0.66 90.1％ Comparative Example 1 Polymer A 62 0.8 88.0 Comparative Example 2 Polymer B 61 0.9 89.0 Comparative Example 3 none 60 1.2 87.0

[0232] According to Table 1, in the dispersant provided in the embodiment of the present application, the first polymer contained therein can act synergistically with the second polymer to reduce the agglomeration between particles and accelerate the dispersion of particles, thereby improving the dispersion effect of the electrode slurry while also increasing the solid content in the electrode slurry and reducing the resistance of the electrode plate, thereby helping to improve the cycle performance of the battery.

[0233] Table 2 lists the weight average molecular weights of the first polymer and the second polymer in the dispersants of Examples 3-7 and related test results.

[0234] Table 2

[0235]

[0236] According to Table 2, in the dispersant provided in the embodiment of the present application, the weight average molecular weights of the first polymer and the second polymer are respectively within the appropriate range, which can increase the solid content in the electrode slurry to reduce the resistance of the electrode plate, thereby achieving the purpose of improving the cycle performance of the battery.

[0237] Table 3 lists the mass ratios of the first polymer and the second polymer in the dispersants of Examples 8-12 and the related test results.

[0238] Table 3

[0239]

[0240] As shown in Table 3, when the mass ratio of the first polymer to the second polymer is set within the above range, the first polymer and the second polymer can better cooperate with each other to accelerate the dispersion of the particles while reducing the agglomeration between the particles, thereby increasing the solid content of the electrode slurry and reducing the resistance of the electrode sheet using the electrode slurry, thereby improving the cycle performance of the battery.

[0241] Table 4 lists the addition amounts of dispersants and related test results of Examples 13-30 respectively.

[0242] Table 4

[0243]

[0244]

[0245] Note: Ttotal is equal to the total stirring time in the positive electrode slurry.

[0246] As shown in Table 4, when the amount of dispersant added is within an appropriate range, the dispersion effect of the electrode slurry can be improved, the stirring time of the slurry can be shortened, the solid content in the slurry can be increased, and the resistance of the electrode sheet can be reduced, thereby improving the cycle performance of the battery.

[0247] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all embodiments falling within the scope of the claims.

Claims

1. A dispersant comprising a first polymer and a second polymer, wherein the weight average molecular weight of the first polymer is smaller than the weight average molecular weight of the second polymer; The first polymer comprises a first structural unit and a second structural unit; The second polymer comprises a third structural unit and a fourth structural unit; in, The first structural unit has the following structural formula: ； The second structural unit has the following structural formula: ； The third structural unit has the following structural formula: ； The fourth structural unit has the following structural formula: ， a is the number of the first structural units, b is the number of the second structural units, c is the number of the third structural units, and d is the number of the fourth structural units.

2. The dispersant according to claim 1, wherein The value range of a is 1-15, and the value range of b is 1-15; The value range of c is 1-200, and the value range of d is 1-200.

3. The dispersant according to claim 1, wherein The weight average molecular weight of the first polymer is less than 1,000.

4. The dispersant according to claim 1, wherein The weight average molecular weight of the second polymer is in the range of 1,000-500,000.

5. The dispersant according to claim 1, wherein The mass ratio of the first polymer to the second polymer is (0.1-10):

1.

6. A method for preparing a dispersant according to any one of claims 1 to 5, comprising: Preparation of the first polymer: dissolving an initiator, a chain transfer agent, and a monomer of the first structural unit in an organic solvent and stirring the mixture under an inert atmosphere to obtain a solution containing the first structural unit; adding the monomer of the second structural unit to the solution containing the first structural unit to react; after the reaction is completed, precipitating, filtering and drying the obtained product to obtain the first polymer; Preparation of the second polymer: dissolving an initiator, a chain transfer agent, and a monomer of the third structural unit in an organic solvent and reacting the mixture with stirring under an inert atmosphere to obtain a solution containing the third structural unit; adding a monomer of the fourth structural unit to the solution containing the third structural unit to carry out a reaction; after the reaction is completed, precipitating, filtering and drying the obtained product to obtain the second polymer; The first polymer and the second polymer are mixed to obtain the dispersant.

7. The preparation method according to claim 6, wherein the stirring linear velocity of the stirring reaction is 2 m / s-8 m / s, and the total stirring time is 120 min-200 min.

8. A slurry composition for forming an electrode film layer, comprising, based on a total mass fraction of 100%,: Dispersant, 0.01%-5%, the dispersant comprising the dispersant according to any one of claims 1 to 5; Binder, 0.5%-10%; active materials, 89%-93.99%; Conductive agent, 0.01%-5%.

9. A battery cell comprising: A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector; A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; A diaphragm, provided between the positive electrode sheet and the negative electrode sheet; Wherein, the positive electrode active material layer and / or the negative electrode active material layer is made using the slurry composition described in claim 8.

10. A battery comprising the battery cell according to claim 9.

11. An electrical device comprising the battery according to claim 10, wherein the battery is used for providing electrical energy.

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