WO2023130886A1 - 负极浆料及其制备方法、负极极片和二次电池 - Google Patents

负极浆料及其制备方法、负极极片和二次电池 Download PDF

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WO2023130886A1
WO2023130886A1 PCT/CN2022/137541 CN2022137541W WO2023130886A1 WO 2023130886 A1 WO2023130886 A1 WO 2023130886A1 CN 2022137541 W CN2022137541 W CN 2022137541W WO 2023130886 A1 WO2023130886 A1 WO 2023130886A1
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negative electrode
slurry
secondary battery
binder
present application
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PCT/CN2022/137541
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English (en)
French (fr)
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木赛男
王宁
王星会
李世松
张盛武
魏志婷
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宁德时代新能源科技股份有限公司
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Priority to EP22918336.3A priority Critical patent/EP4358191A1/en
Publication of WO2023130886A1 publication Critical patent/WO2023130886A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
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    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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    • H01M4/00—Electrodes
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, in particular to a negative electrode slurry and a preparation method thereof, a negative electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device.
  • secondary batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind and solar power plants, as well as electric tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields. Due to the great development of secondary batteries, higher requirements have been put forward for their energy density, cycle performance and storage performance.
  • the amount of inactive materials in the negative electrode film layer is reduced, for example, the amount of negative electrode binder is gradually reduced.
  • the reduction in the amount of negative electrode binder reduces the bonding strength between the negative electrode active material and the negative electrode active material, and the structural stability of the negative electrode sheet becomes poor, which leads to processing problems in the negative electrode sheet, such as cold pressing of the negative electrode sheet. roller, which in turn affects the cycle performance and storage performance of the secondary battery. Therefore, how to improve the cold pressure bonding roll of the negative electrode sheet to improve the cycle performance and storage performance of the secondary battery has become an important topic that needs to be studied urgently in the process of the wide application of the secondary battery.
  • the present application is made in view of the above problems, and its purpose is to improve the cold pressure bonding roll of the negative pole piece, and further improve the cycle performance and storage performance of the secondary battery.
  • the present application provides a negative electrode slurry, a preparation method, a negative electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device.
  • the first aspect of the present application provides a negative electrode slurry, which includes a negative electrode binder, and the negative electrode binder includes a polymer composed of structural units represented by formula (I):
  • the present application has better improved the problem of the cold pressure bonding roll of the negative pole piece by selecting the polymer composed of the structural unit shown in (I) as the negative electrode binder, and improved the cycle performance of the secondary battery and storage performance.
  • the operation is simple, safe and environmentally friendly, which reduces the harm to the environment and personnel, and is more suitable for large-scale application in the industry.
  • the number average molecular weight of the negative electrode binder is 40W-120W, preferably 70W-90W. Regulating the number average molecular weight of the negative electrode binder within the above range, the polar groups on the linear polymer chain of the negative electrode binder can form a "line contact" bond with the surface of the negative electrode active material, which can Improve the long-term bonding strength of the negative pole piece, improve the cohesion of the negative pole piece, stabilize the structure of the negative pole piece, can effectively improve the problem of cold pressure sticking of the negative pole piece, and then improve the cycle performance and storage performance of the secondary battery .
  • the mass percentage of the negative electrode binder is 1%-3.5%, preferably 2%-3%, based on the total mass of the negative electrode slurry. Regulating the mass percentage of the negative electrode binder within the above range can improve the conductivity of the negative electrode sheet while improving the cold pressure bonding roll of the negative electrode sheet. Therefore, it is more beneficial to improve the cycle performance and storage performance of the secondary battery.
  • the negative electrode slurry includes a negative electrode active material, a conductive agent, a dispersant and the negative electrode binder, and the negative electrode active material, the conductive agent, the dispersant, the negative electrode binder
  • the mass ratio of the agent is (93.0-97.0):(1.0-2.0):(1.0-1.5):(1.0-3.5), based on the total mass of the negative electrode slurry.
  • the mass ratio of the negative electrode active material, conductive agent, dispersant and binder in the negative electrode slurry is regulated within the above range, it is easier to coat the negative electrode slurry uniformly on the negative electrode current collector, and the formed The conductivity of the negative pole piece is better, and it is also more conducive to improving the cold pressure bonding roll of the negative pole piece, so that it is more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the negative electrode active material includes at least one of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microspheres, silicon-based materials, tin-based materials, and lithium titanate; optionally, the The graphite includes at least one of artificial graphite and natural graphite; or the silicon-based material includes at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; or the tin-based material includes elemental tin , at least one of tin oxide compounds and tin alloys.
  • the above-mentioned negative electrode active material is selected, it is more conducive to improving the cold-pressed sticking phenomenon of the negative electrode sheet, thereby more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the viscosity of the negative electrode slurry is 4000mPa ⁇ s ⁇ 12000mPa ⁇ s. Regulating the viscosity of the negative electrode slurry within the above range is more conducive to forming a uniform film layer, improving the problem of cold pressure sticking of the negative electrode sheet, and is also more conducive to improving the cycle performance and storage performance of the secondary battery.
  • a second aspect of the present application provides a method for preparing negative electrode slurry, which includes the following steps:
  • the first part of the dispersant accounts for 20% to 50% of the total mass of the dispersant, and the second part of the dispersant accounts for 50% to 80% of the dispersant, wherein the negative electrode binder comprises the formula (I) the polymer that the structural unit shown in constitutes:
  • the above-mentioned preparation method is easy to operate, and the raw materials are easy to obtain, and the raw materials are safe and environmentally friendly, which reduces the harm to the environment and personnel, and is more suitable for large-scale application in the industry.
  • the selection of the negative electrode binder in the preparation method is more conducive to improving the problem of cold pressing and sticking rolls of the negative electrode sheet, and is more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the third aspect of the present application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer is composed of the negative electrode slurry or the negative electrode according to the first aspect of the present application.
  • the coating weight of the negative electrode film layer is 130mg/1540.25mm 2 -190mg/1540.25mm 2 .
  • the above-mentioned negative electrode film layer is prepared from the negative electrode slurry of the first aspect of the present application or the preparation method of the second aspect of the present application, which is more conducive to improving the problem of cold pressing and sticking rolls of the negative electrode sheet, and is more conducive to improving the cycle performance of the secondary battery and storage performance.
  • the negative electrode film layer has a compacted density of 1.50 g/cm 3 to 1.60 g/cm 3 . Regulating the compacted density of the negative electrode film layer within the above range is more conducive to improving the cycle performance and storage performance of the secondary battery.
  • a fourth aspect of the present application provides a secondary battery, including the negative electrode sheet of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery module including the secondary battery of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, including the battery module of the fifth aspect of the present application.
  • the seventh aspect of the present application provides an electric device, including at least one selected from the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect of the present application, or the battery pack of the sixth aspect of the present application. kind.
  • the application provides a negative electrode slurry and its preparation method, negative electrode sheet, secondary battery, battery module, battery pack and electrical device, wherein the negative electrode slurry includes a negative electrode binder, and the negative electrode binder includes the formula A polymer composed of structural units shown in (I).
  • the negative electrode binder of the present application the problem of cold pressure bonding of the negative electrode sheet can be effectively improved, and the negative electrode binder and the negative electrode active material are better coated, which can reduce the rebuilding of the solid electrolyte interface during the cycle, Improve cycle performance and storage performance of secondary batteries.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • Fig. 2 is an exploded view of the secondary battery according to one embodiment of the present application shown in Fig. 1;
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Fig. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in Fig. 4;
  • FIG. 6 is a schematic diagram of an electrical device in which a secondary battery is used as a power source according to an embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • negative electrode binder refers to "polymer A composed of structural units represented by formula (I)".
  • the negative electrode binder As an inactive material in a secondary battery, the negative electrode binder is mainly used to bind negative electrode powder materials (such as negative electrode active materials, conductive agents, and dispersants), so that the negative electrode active materials, conductive agents, and current collectors adhere to each other.
  • negative electrode powder materials such as negative electrode active materials, conductive agents, and dispersants
  • the amount of negative electrode binder used as an inactive material gradually decreases, the bonding strength of the negative electrode sheet decreases, and the structural stability of the negative electrode sheet becomes poor, which leads to the negative electrode During the cold pressing process of the pole piece, there is a serious problem of sticking to the roll, which has a great impact on the cycle performance and storage performance of the secondary battery.
  • emulsion particle type styrene-butadiene latex or modified styrene-butadiene rubber is often used as the binder, but the above-mentioned types of binders are in the negative electrode powder material.
  • the "point contact" bonding between them is not the "line contact” bonding form, so that the negative electrode sheet lacks long-range bonding ability as a whole, so it cannot solve the problem of sticking rolls in the negative electrode sheet cold pressing process.
  • oily agents are added to the negative electrode slurry or release agents are used to coat the rolls.
  • the present application provides a negative electrode slurry and a preparation method thereof, a negative electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device.
  • the application proposes a negative electrode slurry, which includes a negative electrode binder, and the negative electrode binder includes a polymer A composed of structural units represented by formula (I):
  • the side chain group of the negative electrode binder contains More polar amido (-CO-NH 2 ), lithium carboxylate (-COOLi), carboxyl (-COOH), and groups on the surface of the negative electrode active material (for example, a large number of epoxy groups, carbonyl groups and hydroxyl groups, etc.)
  • Form intermolecular force Van der Waals force or hydrogen bond
  • chemical bond
  • the long-range bonding strength between the active materials can improve the cohesion of the negative electrode sheet, improve the problem of sticking rolls in the cold pressing process of the negative electrode sheet, and then reduce the loss of the negative electrode active material during the preparation of the negative electrode sheet; on the other hand, the negative electrode
  • the active material provides a coating layer containing the negative electrode binder, which can reduce the loss of the SEI film (solid electrolyte interface film) during the cycle of the secondary battery, thereby reducing the active lithium content in the electrolyte due to the reconstruction of the SEI film.
  • the cycle performance and storage performance of the secondary battery are significantly improved.
  • the process is simple, safe and environmentally friendly, reducing the harm to the environment and personnel, and is more suitable for large-scale application in the industry.
  • the number average molecular weight of the negative electrode binder is 40W-120W, preferably 70W-90W.
  • the number average molecular weight of the negative electrode binder is less than 40W, the number of effective groups (such as amido (-CO-NH 2 ), lithium carboxylate (-COOLi), carboxyl (-COOH), etc.) acting on it is limited, The negative electrode active material, conductive agent and negative electrode current collector cannot be effectively bonded; when the number average molecular weight of the negative electrode binder is greater than 120W, the negative electrode binder cannot be completely dissolved in the deionized water solvent system and is in the negative electrode sheet Decreased dispersibility will reduce the bonding effect.
  • the polar groups on the linear polymer chain of the negative electrode binder can form a "line contact" bond with the surface of the negative electrode active material, which can Improving the long-term bonding strength of the negative pole piece, improving the cohesion of the negative pole piece, stabilizing the structure of the negative pole piece, can effectively improve the problem of sticking rollers in the cold pressing process of the negative pole piece, and then improve the cycle performance of the secondary battery and storage performance.
  • the negative pole piece also has a suitable resistance.
  • the mass percentage of the negative electrode binder is 1%-3.5%, preferably 2%-3%, based on the total mass of the negative electrode slurry.
  • the mass percentage of the negative electrode binder in the negative electrode slurry is less than 1%, no conductive network is formed between the particles of the conductive agent and the negative electrode active material, resulting in an increase in the path of electron transmission and slow electron transmission, resulting in negative electrode sheet
  • the mass percentage of the negative electrode binder gradually increases, the conductive network between the conductive agent and the particles of the negative electrode active material is gradually established, and the conductivity gradually increases.
  • the negative electrode binder When the mass percentage in the negative electrode slurry is greater than 3.5%, the free negative electrode binder content increases, and the excess negative electrode binder moves freely, which will affect the infiltration of the electrolyte in the negative electrode film layer, thereby affecting the secondary battery. Excellent cycle performance and storage performance; and the negative electrode binder itself has no conductivity, and the internal resistance of the negative electrode sheet will increase. Regulating the mass percentage of the negative electrode binder within the above range can improve the conductivity of the negative electrode sheet while improving the cold pressure bonding roll of the negative electrode sheet. Therefore, it is more beneficial to improve the cycle performance and storage performance of the secondary battery.
  • the negative electrode slurry includes negative electrode active material, conductive agent, dispersant and negative electrode binder, and the mass ratio of negative electrode active material, conductive agent, dispersant and negative electrode binder is (93.0 ⁇ 97):( 1.0-2.0):(1.0-1.5):(1.0-3.5), based on the total mass of the negative electrode slurry. It can be understood that the total mass of the negative electrode slurry is the sum of the mass of the negative electrode active material, conductive agent, dispersant and negative electrode binder.
  • the mass ratio of the negative electrode active material, conductive agent, dispersant and binder in the negative electrode slurry is regulated within the above range, it is easier to coat the negative electrode slurry uniformly on the negative electrode current collector, and the formed The conductivity of the negative pole piece is better, and it is also more conducive to improving the sticking problem in the cold pressing process of the negative pole piece, so that it is more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the negative electrode active material includes at least one of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microspheres, silicon-based materials, tin-based materials, and lithium titanate; optionally, graphite includes artificial At least one of graphite and natural graphite; or silicon-based materials include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; or tin-based materials include elemental tin, tin oxide compounds, and tin alloys at least one of .
  • the negative electrode active material includes graphite, and the graphite includes at least one of artificial graphite and natural graphite.
  • the graphite includes at least one of artificial graphite and natural graphite.
  • This "line contact” not only increases the long-term bond strength of the negative electrode sheet, but also improves the negative electrode sheet.
  • the cohesive force stabilizes the structure of the negative electrode sheet, improves the problem of cold pressure sticking of the negative electrode sheet, and is better coated with the surface of the negative electrode active material, which can reduce the reconstruction of the SEI film during the secondary battery cycle, thereby improving the secondary battery. Cycle performance and storage performance of secondary batteries.
  • the present application has no particular limitation on the particle size of the negative electrode active material, as long as the purpose of the present application can be achieved.
  • the particle size distribution of the negative active material is as follows: Dv10 is 6.5 ⁇ m ⁇ 11.5 ⁇ m, Dv50 is 13.5 ⁇ m ⁇ 11.5 ⁇ m, and Dv90 is 25.0 ⁇ m ⁇ 50.0 ⁇ m.
  • the present application has no particular limitation on the type of the conductive agent, as long as the purpose of the present application can be achieved.
  • the conductive agent includes at least one of acetylene black, conductive carbon black (Super-P), carbon nanotubes, Ketjen black, graphene and carbon nanofibers.
  • the conductive agent in the above preferred range has good long-range conductivity, and can reduce the amount of conductive agent while making the conductive network of the negative electrode sheet have good stability during the secondary battery cycle expansion process.
  • a complete conductive network can be formed in the negative electrode sheet, which can effectively reduce the electron and ion diffusion resistance of the secondary battery, so that the secondary battery has more excellent kinetic performance.
  • the present application has no particular limitation on the type of dispersant, as long as the purpose of the present application can be achieved.
  • the dispersant is sodium carboxymethyl cellulose, and the molecular weight of sodium carboxymethyl cellulose is 5W-10W, and the degree of substitution is 0.55-0.95.
  • the formed negative electrode slurry can have a suitable viscosity, and the negative electrode slurry has good fluidity.
  • sodium carboxymethylcellulose with a degree of substitution in the above-mentioned preferred range sodium carboxymethylcellulose has better emulsifying performance, so that the negative electrode active material can be better infiltrated in the negative electrode slurry.
  • the above “degree of substitution” is also called the degree of etherification, which is the average number of H in the three hydroxyl groups (-OH) on the cellulose molecular unit structure replaced by -CH 2 COONa.
  • the viscosity of the negative electrode slurry is 4000 mPa ⁇ s ⁇ 12000 mPa ⁇ s.
  • the viscosity of the negative electrode slurry is less than 4000mPa ⁇ s, the viscosity of the negative electrode slurry is too small, the negative electrode slurry is not easy to bond on the negative electrode current collector, and the weight consistency of different regions in the prepared negative electrode film layer is relatively poor.
  • the difference is relatively large; when the viscosity of the negative electrode slurry is greater than 12000mPa ⁇ s, the viscosity of the negative electrode slurry is too high and the fluidity is poor, which is not conducive to the formation of a uniform negative electrode film layer, and will make the negative electrode sheet sticky during the cold pressing process. Rollers are more of a problem. Regulating the viscosity of the negative electrode slurry within the above range is more conducive to forming a uniform film layer, improving the problem of cold pressure sticking of the negative electrode sheet, and is also more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the solid content of the negative electrode slurry is 40wt%-60wt%.
  • the solid content is less than 40wt%, there is too much deionized water in the negative electrode slurry, and higher temperature and slow drying speed are required to dry the negative electrode slurry when baking in the oven, not only during the cold pressing process of the negative electrode sheet It is easy to stick to the roll in the middle, and it also needs to consume a lot of energy; when the solid content is greater than 60wt%, the particles of the negative electrode active material are not uniformly dispersed. Thus affecting the cycle performance and storage performance of the secondary battery. Regulating the solid content of the negative electrode slurry within the above range is more conducive to improving the problem of cold pressing and sticking of the negative electrode sheet, and improving the cycle performance and storage performance of the secondary battery.
  • a second aspect of the present application provides a method for preparing negative electrode slurry, which includes the following steps:
  • the first part of the dispersing agent accounts for 20% to 50% of the total mass of the dispersing agent, and the second part of the dispersing agent accounts for 50% to 80% of the dispersing agent, wherein the negative electrode binder includes a compound consisting of structural units represented by formula (I) polymer:
  • the addition of the first part of the dispersant can modify the polarity of the surface of the negative electrode active material, so that the negative electrode active material and deionized water can achieve a better wetting effect.
  • the addition of the second part of the dispersant makes the components in the negative electrode slurry uniformly dispersed, making the negative electrode slurry more stable. Regulating the mass ratio of the first part of the dispersant and the second part of the dispersant in the dispersant within the above-mentioned range is more conducive to exerting the above-mentioned function of the dispersant.
  • the present application has no special limitation on the content of the above-mentioned deionized water, as long as the purpose of the present application can be achieved.
  • the present application has no special limitation on the manner, speed and time of "stirring" in the above steps, as long as the purpose of the present application can be achieved.
  • the present application has no special limitation on the above-mentioned "viscosity adjustment” method, as long as the viscosity of the negative electrode slurry is adjusted within the range of 4000mPa ⁇ s to 12000mPa ⁇ s to achieve the purpose of the present application.
  • the present application has no special limitation on the above-mentioned "vacuum degassing" method and vacuum degree, as long as the purpose of the present application can be achieved.
  • the degree of vacuum may be -50KPa or more.
  • the preparation method of the negative electrode slurry provided by the second aspect of the present application is simple to operate, the raw materials are easy to obtain, and the raw materials are safe and environmentally friendly, which reduces the harm to the environment and personnel, and is more suitable for large-scale application in the industry. Moreover, the selection of the negative electrode binder in the preparation method is more conducive to improving the problem of cold pressure bonding of the negative electrode sheet, and further conducive to improving the cycle performance and storage performance of the secondary battery.
  • a third aspect of the present application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, The negative electrode film layer is arranged on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode film layer is prepared from the negative electrode slurry of the first aspect of the present application or the preparation method of the second aspect of the present application, and the coating weight of the negative electrode film layer is 130mg/1540.25mm 2 -190mg/1540.25mm 2 .
  • the negative electrode film layer has a suitable content of negative electrode active material under the same area, so that the secondary battery can have good energy density.
  • the above-mentioned negative electrode film layer is prepared from the negative electrode slurry of the first aspect of the present application or the preparation method of the second aspect of the present application, which is more conducive to improving the problem of cold pressing and sticking rolls of the negative electrode sheet, and is more conducive to improving the cycle of the secondary battery. performance and storage performance.
  • the negative electrode film layer has a compacted density of 1.50 g/cm 3 to 1.60 g/cm 3 .
  • the compaction density of the negative electrode film is less than 1.50g/ cm3 , the gap between the particles of the negative electrode active material is too large, and the contact between the particles of the negative electrode active material becomes poor, which will affect the interface stability of the negative electrode film, and then affect The cycle performance and storage performance of the secondary battery; when the compacted density of the negative electrode film layer is greater than 1.60g/cm 3 , the risk of breaking the negative electrode active material particles increases, which will also affect the interface stability of the negative electrode film layer, thereby affecting the secondary battery. Battery cycle performance and storage performance. Regulating the compacted density of the negative electrode film layer within the above range is more conducive to improving the cycle performance and storage performance of the secondary battery.
  • the cohesion of the negative electrode sheet is 33.5N/m-80.1N/m. It shows that the negative electrode sheet of the present application has good cohesive force, stabilizes the structure of the negative electrode sheet, improves the problem of cold pressure sticking of the negative electrode sheet, and further improves the cycle performance and storage performance of the secondary battery.
  • cohesive force refers to the force inside the negative electrode film layer, that is, the force between the negative electrode active material and the negative electrode active material in the negative electrode film layer.
  • the present application has no particular limitation on the thickness of the negative electrode sheet and the negative electrode film layer, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode sheet is 113.5.4 ⁇ m-172.4 ⁇ m
  • the single-layer thickness of the negative electrode film layer is 52.8 ⁇ m-82.2 ⁇ m.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid Ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE, etc.)
  • the negative electrode sheet can be prepared in the following manner: the negative electrode slurry in any of the above embodiments is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained .
  • the positive pole piece includes a positive current collector and a positive film layer arranged on at least one surface of the positive current collector.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can 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 can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), 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 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 )), lithium nickel cobalt aluminum oxide (such as LiN
  • olivine-structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), phosphoric acid At least one of a composite material of lithium manganese and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate
  • phosphoric acid At least one of a composite material of lithium manganese and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • the positive electrode film layer may further optionally include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer may also optionally include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • electrolytes can be liquid, gel or all solid.
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the solvent may be selected from 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 At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may optionally include additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film 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 any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • a secondary battery which includes the negative electrode sheet described in any one of the above embodiments.
  • the secondary battery of the present application may refer to the secondary battery described in any of the above-mentioned embodiments.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-shaped secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating cavity. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • a plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 6 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • Negative electrode active material artificial graphite, conductive agent conductive carbon, the first part of dispersant sodium carboxymethyl cellulose according to the mass of 2375g, 37.5gg, 5g were added to the mixer for dry powder mixing and stirring for 15min, wherein the stirring revolution was 25rpm, and the stirring rotation was 800rpm to obtain a uniform powder;
  • the method of adding deionized water is to add a small amount of multiple times, and stir for 20 minutes.
  • the stirring revolution is 10 rpm, and the stirring rotation is 900 rpm to prepare a slurry with a viscosity of 8000mPa ⁇ s. ;
  • the negative electrode slurry prepared above was uniformly coated on one surface of a copper foil with a thickness of 8 ⁇ m, the coating speed was 30 m/min, and the coating mass was 160 mg/1540.25 mm 2 . Drying at 98°C, after cold pressing, a double-sided coated negative electrode sheet with a negative film layer thickness of 67.0 ⁇ m was obtained, and then a negative electrode sheet with a specification of 76mm ⁇ 851mm was obtained through tab forming, slitting and other processes. Among them, the cold pressing pressure is 50 tons, the cold pressing speed is 40 m/min, and the compacted density of the negative electrode film layer is 1.55 g/cm 3 .
  • the positive electrode slurry is uniformly coated on one surface of an aluminum foil with a thickness of 13 ⁇ m, dried at 90°C, and cold-pressed to obtain a double-sided coated positive electrode sheet with a single layer thickness of the positive electrode film layer of 55 ⁇ m, and then passed through the electrode Ear forming, slitting and other processes to obtain positive pole pieces with specifications of 74mm ⁇ 867mm.
  • a polyethylene film with a thickness of 14 ⁇ m was selected as the separator.
  • the above-mentioned positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is between the positive electrode sheet and the negative electrode sheet to play an isolation role, and then wind the electrode assembly; place the electrode assembly in the outer packaging shell After being dried, the electrolyte solution is injected, and the secondary battery is obtained through processes such as vacuum packaging, standing still, chemical formation, and shaping.
  • Example 1-1 Except for adjusting the number average molecular weight of the negative electrode binder according to Table 1, the rest is the same as that of Example 1-1, and negative electrode binders with different number average molecular weights are provided by Zhejiang Zhongke Lide New Material Co., Ltd.
  • Example 1-1 Except for adjusting the viscosity of the slurry according to Table 3, the rest is the same as that of Example 1-1, wherein the viscosity of the slurry can be regulated by adding deionized water.
  • Example 1-1 Except for adjusting the coating weight of the negative electrode film layer according to Table 4, the rest is the same as that of Example 1-1.
  • SBR styrene-butadiene rubber
  • the mass (g) of the powder scraped off by the scraper from the surface of the cold-pressing roll was collected during the cold-pressing process of the negative electrode sheets in each example and comparative example.
  • the amount of scraped powder is used to characterize the problem of cold-pressed roll sticking of the negative pole piece. The more scraped powder, the more serious the problem of cold-pressed sticky roll of the negative pole piece.
  • Stick a low-adhesive green adhesive tape (model: MD-XTG-620-2335L) with a width of 20mm and a length of 180mm to the surface of the test surface, and roll it three times in the same direction with a pressure roller.
  • the negative pole pieces of each embodiment and comparative example were tested with a battery internal resistance tester (model: BER1100) of Yuanneng Technology.
  • the resistance test process of the negative pole piece is as follows: Take a 4cm ⁇ 25cm area sample along the longitudinal direction of the negative pole piece, slowly open the compressed air valve, connect the red and black test lines of the internal resistance meter to the test line of the pole piece resistance tester, open the internal resistance instrument, pressure display power supply, and connected to the computer.
  • the secondary battery prepared by each embodiment and comparative example is fully charged to 4.2V with a constant current of 0.33C, charged at a constant voltage of 4.2V to a cut-off of 0.05C, and then discharged to 2.5V with a constant current of 0.33V.
  • the capacity is recorded as C 0 , and then fully charged to 4.2V with a constant current of 0.33C, charged at a constant voltage of 4.2V to a cut-off of 0.05C, then placed in an incubator, stored at 25°C for 30 days, taken out, and discharged at 0.33C to 2.5 V, then fully charged to 4.2V with a constant current of 0.33C, charged at a constant voltage of 4.2V to a cut-off of 0.05C, and then discharged to 2.5V with a constant current of 0.33V, and the discharge capacity at this time is recorded as C 30 .
  • Capacity retention (%) after 30 days C 30 /C 0 ⁇ 100%.
  • the negative electrode sheets and secondary batteries of Examples 1-1 to 1-6 when selecting the negative electrode binder of the application, the negative electrode sheets of each embodiment have higher cohesive force, relatively
  • the secondary battery of each embodiment has good cycle performance and storage performance due to the small amount of scraped powder.
  • Comparative Example 1 when a negative electrode binder outside the scope of the present application is selected, the cycle performance and storage performance of the secondary battery have not been effectively improved.
  • Example 1-1 to Example 1-6 From Example 1-1 to Example 1-6, it can be seen that when the number-average molecular weight of the negative electrode binder is within the scope of the present application, the cold pressure sticking phenomenon of the negative pole piece is improved, and the obtained secondary battery has more Good cycle performance and storage performance.
  • Example 1-1 From Example 1-1, Example 2-1 to Example 2-5, it can be seen that when the mass percentage of the negative electrode binder in the negative electrode slurry is within the scope of this application, the cold pressure bonding of the negative electrode sheet The roll phenomenon is improved, and the resulting secondary battery has better cycle performance and storage performance. Among them, in Example 1-1, when the mass percentage of the negative electrode binder is 2.5%, the cycle performance and storage performance of the secondary battery are the best.
  • Example 3-1 to Example 3-2 From Example 1-1, Example 3-1 to Example 3-2, it can be seen that when the viscosity of the negative electrode slurry is within the scope of the application, a negative electrode sheet and a secondary battery with good performance can be prepared, wherein, The cold-pressure sticking phenomenon of the negative pole piece is improved, and the obtained secondary battery has better cycle performance and storage performance.
  • Example 4-1 to Example 4-6 it can be seen that when the coating weight and compaction density of the negative electrode film layer are within the scope of this application, a negative electrode sheet with good performance can be prepared And a secondary battery, wherein the cold-pressed sticking phenomenon of the negative pole piece is improved, and the obtained secondary battery has better cycle performance and storage performance.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种负极浆料及其制备方法、负极极片、二次电池、电池模块、电池包和用电装置，其中，负极浆料包括负极粘结剂，负极粘结剂包括由式（I）所示的结构单元构成的聚合物。通过选用本申请的负极粘结剂，能够有效改善负极极片冷压粘辊的问题，而且该负极粘结剂与负极活性材料包覆地更好，能够减少循环过程中固体电解质界面的重建，提高二次电池的循环性能和存储性能。

Description

负极浆料及其制备方法、负极极片和二次电池
本申请要求申请日为2022年1月4日提交的202210007260.6的优先权
技术领域
本申请涉及锂电池技术领域，尤其涉及一种负极浆料及其制备方法、负极极片、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广泛，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于二次电池取得了极大的发展，因此对其能量密度、循环性能和存储性能等也提出了更高的要求。
现有技术中为了提高二次电池的能量密度，减少了负极膜层中的非活性材料的用量，例如，负极粘结剂的用量逐渐减少。负极粘结剂的用量减少，使负极活性材料与负极活性材料之间的粘结强度下降，负极极片的结构稳定性变差，从而导致负极极片出现加工问题，例如负极极片冷压粘辊，进而影响二次电池的循环性能和存储性能。因此，如何改善负极极片冷压粘辊进而改善二次电池的循环性能和存储性能，已成为二次电池在广泛应用的过程中一项亟需研究的重要课题。
发明内容
本申请是鉴于上述课题而进行的，其目的在于改善负极极片冷压粘辊，进而改善二次电池的循环性能和存储性能。
为了达到上述目的，本申请提供了一种负极浆料、制备方法、负极极片、二次电池、电池模块、电池包和用电装置。
本申请的第一方面提供了一种负极浆料，其包括负极粘结剂，所述负极粘结剂包括由式(I)所示的结构单元构成的聚合物：
Figure PCTCN2022137541-appb-000001
由此，本申请通过选用由(I)所示的结构单元构成的聚合物作为负极粘结剂，更好地改善了负极极片冷压粘辊的问题，并且提高了二次电池的循环性能和存储性能。此外，该负极粘结剂使用过程中，操作简单、安全环保，减少了对环境和人员的危害，更适合行业内规模化应用。
在任意实施方式中，所述负极粘结剂的数均分子量为40W～120W，优选为70W～90W。将负极粘结剂的数均分子量调控在上述范围内，负极粘结剂的线性高分子聚合物链上的极性基团能够与负极活性材料表面之间形成“线接触式”粘结，能够提高负极极片的长程粘结强度，提高了负极极片的内聚力，稳定了负极极片的结构，能够有效改善负极极片冷压粘辊的问题，进而提高二次电池的循环性能和存储性能。
在任意实施方式中，所述负极粘结剂的质量百分含量为1％～3.5％，优选为2％～3％，基于所述负极浆料的总质量计。将负极粘结剂的质量百分含量调控在上述范围内，能够在改善负极极片冷压粘辊的同时，改善负极极片的导电性。从而更利于改善二次电池的循环性能和存储性能。
在任意实施方式中，所述负极浆料包括负极活性材料、导电剂、分散剂和所述负极粘结剂，所述负极活性材料、所述导电剂、所述分散剂、所述负极粘结剂的质量比为(93.0～97.0)∶(1.0～2.0)∶(1.0～1.5)∶(1.0～3.5)，基于所述负极浆料的总质量计。将负极活性材料、导电剂、分散剂和粘结剂在负极浆料中的质量比调控在上述范围内时，负极浆料涂覆于负极集流体上时更容易涂覆均匀，且形成后的负极极片的导电性更好，也更利于改善负极极片冷压粘辊，从而更利于改善二次电池的循环性能和存储性能。
在任意实施方式中，所述负极活性材料包括石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料和钛酸锂中的至少一种；可选地，所述石墨包括人造石墨和天然石墨中的至少一种；或所述硅基材料包括单质硅、硅氧化合物、硅碳复合物和硅合金中的至少一种；或所述锡基材料包括单质锡、锡氧化合物和锡合金中的至少一种。选用上述负极活性材料时，更利于改善负极极片冷压粘辊现象，从而更利于改善二次电池的循环性能和存储性能。
在任意实施方式中，所述负极浆料的粘度为4000mPa·s～12000mPa·s。将负极浆料的粘度调控在上述范围内，更利于形成均匀的膜层，改善负极极片冷压粘辊的问题，也更利于改善二次电池的循环性能和存储性能。
本申请的第二方面提供一种负极浆料的制备方法，其包括以下步骤：
将负极活性材料、导电剂、第一部分分散剂混合均匀，制得均匀粉末；
在所述均匀粉末中加入去离子水，搅拌，制得第一均匀浆料；
将第二部分分散剂和去离子水加入所述第一均匀浆料中，搅拌，制得第二均匀浆料；
在所述第二均匀浆料中加入负极粘结剂，搅拌，调粘，真空除气，得到所述负极浆料；
所述第一部分分散剂占所述分散剂总质量的20％～50％，所述第二部分分散剂占所述分散剂的50％～80％，其中，所述负极粘结剂包括由式(I)所示的结构单元构成的聚合物：
Figure PCTCN2022137541-appb-000002
由此，上述制备方法操作简单，原料易得，且原料安全环保，减少了对环境和人员的危害，更适合行业内规模化应用。并且，制备方法中负极粘结剂的选用，更利于改善负极极片冷压粘辊的问题，更利于改善二次电池的循环性能和存储性能。
本申请的第三方面提供一种负极极片，其包括负极集流体以及设置在所述负极集流体至少一个表面的负极膜层，所述负极膜层由本申请的第一方面的负极浆料或者由本申请的第二方面的制备方法制备而成，所述负极膜层的涂布重量为130mg/1540.25mm 2～190mg/1540.25mm 2。上述负极膜层由本申请的第一方面的负极浆料或者由本申请的第二方面的制备方法制备而成，更利于改善负极极片冷压粘辊的问题，更利于改善二次电池的循环性能和存储性能。
在任意实施方式中，所述负极膜层的压实密度为1.50g/cm 3～1.60g/cm 3。将负极膜层的压实密度调控在上述范围内，更利于改善二次电池的循环性能和存储性能。
本申请的第四方面提供一种二次电池，包括本申请第三方面的负极极片。
本申请的第五方面提供一种电池模块，包括本申请的第四方面的二次电池。
本申请的第六方面提供一种电池包，包括本申请的第五方面的电池模块。
本申请的第七方面提供一种用电装置，包括选自本申请的第四方面的二次电池、本申 请的第五方面的电池模块或本申请的第六方面的电池包中的至少一种。
本申请的有益效果：
本申请提供的一种负极浆料及其制备方法、负极极片、二次电池、电池模块、电池包和用电装置，其中，负极浆料包括负极粘结剂，负极粘结剂包括由式(I)所示的结构单元构成的聚合物。通过选用本申请的负极粘结剂，能够有效改善负极极片冷压粘辊的问题，而且该负极粘结剂与负极活性材料包覆地更好，能够减少循环过程中固体电解质界面的重建，提高二次电池的循环性能和存储性能。
附图说明
图1是本申请一实施方式的二次电池的示意图；
图2是图1所示的本申请一实施方式的二次电池的分解图；
图3是本申请一实施方式的电池模块的示意图；
图4是本申请一实施方式的电池包的示意图；
图5是图4所示的本申请一实施方式的电池包的分解图；
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的负极浆料及其制备方法、负极极片、二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出 了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选/优选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选/优选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
本申请说明书中，为了简洁描述，术语“负极粘结剂”是指“由式(I)所示的结构单元构成的聚合物A”。
[负极浆料]
负极粘结剂作为二次电池中的非活性材料，其作用主要是粘结负极粉体材料(例如负极活性材料、导电剂、分散剂)，使负极活性材料、导电剂和集流体等相互粘结在一起，但是随着二次电池能量密度的提高，作为非活性材料的负极粘结剂用量逐渐减少，负极极片粘结强度下降，负极极片的结构稳定性变差，从而导致制备负极极片的冷压过程中出现严重的粘辊的问题，对二次电池的循环性能和存储性能有较大影响。
目前，为了解决负极极片制备过程中的冷压粘辊的问题，往往使用乳液颗粒型丁苯乳 胶或改性丁苯橡胶作为粘结剂，但上述类型的粘结剂在负极粉体材料之间为“点接触”粘结，而非“线接触式”粘结形式，使负极极片整体缺乏长程的粘结能力，从而无法解决负极极片冷压工艺中粘辊问题。为了解决负极极片制备过程中的冷压粘辊的问题，在负极浆料中添加油性剂或使用离型剂涂辊，但油性剂和离型剂均具有毒性，易产生环境污染、人员中毒等危害，还会影响二次电池的存储性能。由此，找到一种使负极粉体材料之间为“线接触式”粘结形式，且对环境、人员等没有危害的负极粘结剂，成为本申请人研究的重点方向。基于此，本申请提供了一种负极浆料及其制备方法、负极极片、二次电池、电池模块、电池包和用电装置。
本申请的一个实施方式中，本申请提出了一种负极浆料，其包括负极粘结剂，负极粘结剂包括由式(I)所示的结构单元构成的聚合物A：
Figure PCTCN2022137541-appb-000003
虽然机理尚不明确，但本申请人意外地发现：本申请选用由(I)所示的结构单元构成的聚合物A作为负极粘结剂时，该负极粘结剂的侧链基团上含有极性较大的酰氨基(-CO-NH 2)、羧酸锂(-COOLi)、羧基(-COOH)，与负极活性材料表面的基团(例如，大量环氧基、羰基和羟基等)形成分子间的作用力(范德华力或氢键)或者化学键，进而与负极各粉体材料形成“线接触式”粘结形式，这种“线接触式”的粘结形式，一方面能够增加负极活性材料之间的长程粘结强度，提高负极极片的内聚力，改善负极极片冷压工艺中粘辊的问题，进而减少负极活性材料在负极极片制备过程中的损失；另一方面为负极活性材料提供含有负极粘结剂的包覆层，能够减少二次电池循环过程中SEI膜(固体电解质界面膜)的损失，从而因SEI膜重建造成的电解液中的活性锂含量下降。通过以上两方面的作用，二次电池的循环性能和存储性能得到显著提升。此外，该负极粘结剂应用过程中，工艺简单、安全环保，减少对环境和人员的危害，更适合行业内规模化应用。
在一些实施方式中，负极粘结剂的数均分子量为40W～120W，优选为70W～90W。负极粘结剂的数均分子量小于40W时，其上起作用的有效基团(例如酰氨基(-CO-NH 2)、羧酸锂(-COOLi)、羧基(-COOH)等)数量有限，无法有效地将负极活性材料、导电剂以及负极集流体进行粘结；负极粘结剂的数均分子量大于120W时，负极粘结剂在去离子水溶 剂体系中不能溶解完全且在负极极片中的分散性下降，会降低粘结效果。将负极粘结剂的数均分子量调控在上述范围内，负极粘结剂的线性高分子聚合物链上的极性基团能够与负极活性材料表面之间形成“线接触式”粘结，能够提高负极极片的长程粘结强度，提高了负极极片的内聚力，稳定负极极片的结构，能够有效改善负极极片冷压工艺中的粘辊的问题，进而提高二次电池的循环性能和存储性能。并且，负极极片也具有合适的电阻。
在一些实施方式中，负极粘结剂的质量百分含量为1％～3.5％，优选为2％～3％，基于负极浆料的总质量计。负极粘结剂在负极浆料中的质量百分含量小于1％时，导电剂、负极活性材料各颗粒之间没有形成导电网络，造成电子传输的路径增大，电子传输缓慢，导致负极极片内阻增大，随着负极粘结剂的质量百分含量的逐渐增大，导电剂、负极活性材料各颗粒之间的导电网络逐渐建立完善，导电性逐渐增加，但是，当负极粘结剂在负极浆料中的质量百分含量大于3.5％时，自由的负极粘结剂含量增多，多余的负极粘结剂自由移动，将影响电解液在负极膜层中的浸润，进而影响二次电池的循环性能和存储性能；并且负极粘结剂本身没有导电性，负极极片的内阻将增大。将负极粘结剂的质量百分含量调控在上述范围内，能够在改善负极极片冷压粘辊的同时，改善负极极片的导电性。从而更利于改善二次电池的循环性能和存储性能。
在一些实施方式中，负极浆料包括负极活性材料、导电剂、分散剂和负极粘结剂，负极活性材料、导电剂、分散剂、负极粘结剂的质量比为(93.0～97)∶(1.0～2.0)∶(1.0～1.5)∶(1.0～3.5)，基于负极浆料的总质量计。可以理解，负极浆料的总质量即为负极活性材料、导电剂、分散剂和负极粘结剂的质量和。将负极活性材料、导电剂、分散剂和粘结剂在负极浆料中的质量比调控在上述范围内时，负极浆料涂覆于负极集流体上时更容易涂覆均匀，且形成后的负极极片的导电性更好，也更利于改善负极极片冷压工艺中的粘辊问题，从而更利于改善二次电池的循环性能和存储性能。
在一些实施方式中，负极活性材料包括石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料和钛酸锂中的至少一种；可选地，石墨包括人造石墨和天然石墨中的至少一种；或硅基材料包括单质硅、硅氧化合物、硅碳复合物和硅合金中的至少一种；或锡基材料包括单质锡、锡氧化合物和锡合金中的至少一种。
选用上述负极活性材料时，更利于改善负极极片冷压粘辊现象，从而更利于改善二次电池的循环性能和存储性能。优选地，负极活性材料包括石墨，石墨包括人造石墨和天然石墨中的至少一种。石墨各颗粒表面除碳碳键外，还存在大量的环氧基、羰基和羟基，可以与负极粘结剂的侧链基团-CO-NH 2、-COOLi和-COOH这些强极性基团形成分子间的作用 力或者化学键，进而与负极各粉体材料形成“线接触式”粘结形式，这种“线接触式”不仅增加了负极极片的长程粘结强度，提高负极极片的内聚力，稳定了负极极片的结构，改善了负极极片冷压粘辊的问题，而且与负极活性材料表面包覆的更好，能够减少二次电池循环过程中SEI膜的重建，从而提高二次电池的循环性能和存储性能。
本申请对负极活性材料的粒径没有特别限制，只要能够实现本申请目的即可。优选地，在一些实施方式中，负极活性材料的粒径分布为：Dv10为6.5μm～11.5μm、Dv50为13.5μm～11.5μm、Dv90为25.0μm～50.0μm。将负极活性材料的粒径分布调控在上述优选范围内时，更利于改善负极极片冷压粘辊的问题，从而更利于改善二次电池的循环性能和存储性能。
本申请对导电剂的种类没有特别限制，只要能够实现本申请目的即可。优选地，在一些实施方式中，导电剂包括乙炔黑、导电炭黑(Super-P)、碳纳米管、科琴黑、石墨烯及碳纳米纤维中的至少一种。上述优选范围的导电剂，具有良好的长程导电能力，能够在降低导电剂用量的同时，使负极极片在二次电池循环膨胀过程中的导电网络具有良好的稳定性。并且，在负极极片中可形成完整的导电网络，有效降低二次电池的电子及离子扩散阻抗，使二次电池具有更优异的动力学性能。
本申请对分散剂的种类没有特别限制，只要能够实现本申请目的即可。优选地，在一些实施方式中，分散剂为羧甲基纤维素钠，且羧甲基纤维素钠的分子量为5W～10W，取代度为0.55～0.95。选用分子量在上述优选范围的羧甲基纤维素钠时，形成的负极浆料能够具有合适的粘度，且负极浆料具有良好的流动性。选用取代度在上述优选范围的羧甲基纤维素钠时，羧甲基纤维素钠的乳化性能更好，从而使负极活性材料能更好地浸润于负极浆料中。上述“取代度”也称醚化度，是纤维素分子单元结构上3个羟基(-OH)中的H被-CH 2COONa取代的平均数目。
在一些实施方式中，负极浆料的粘度为4000mPa·s～12000mPa·s。负极浆料的粘度小于4000mPa·s时，负极浆料的粘度过小，负极浆料不易粘结于负极集流体上，且制备得到负极膜层中不同区域的重量一致性比较差，涂布过程的差异性比较大；负极浆料的粘度大于12000mPa·s时，负极浆料的粘度过大，流动性较差，不利于形成均匀的负极膜层，且会使负极极片冷压工艺中粘辊的问题更严重。将负极浆料的粘度调控在上述范围内，更利于形成均匀的膜层，改善负极极片冷压粘辊的问题，也更利于改善二次电池的循环性能和存储性能。
在一些实施方式中，负极浆料的固含量为40wt％～60wt％。固含量小于40wt％时，负极 浆料中的去离子水过多，在烘箱中烘烤时需要更高的温度和慢烘干速度才能将负极浆料烘干，不仅在负极极片冷压过程中容易粘辊，还需要消耗大量的能量；固含量大于60wt％时，负极活性材料颗粒分散不均匀，在搅拌负极浆料时，负极活性材料不易分散，容易在负极浆料中团聚发生沉降，从而影响二次电池的循环性能和存储性能。将负极浆料的固含量调控在上述范围内，更利于改善负极极片冷压粘辊的问题，改善二次电池的循环性能和存储性能。
本申请的第二方面提供一种负极浆料的制备方法，其包括以下步骤：
将负极活性材料、导电剂、第一部分分散剂混合均匀，制得均匀粉末；
在均匀粉末中加入去离子水，搅拌，制得第一均匀浆料；
将第二部分分散剂和去离子水加入第一均匀浆料中，搅拌，制得第二均匀浆料；
在第二均匀浆料中加入负极粘结剂，搅拌，调粘，真空除气，得到负极浆料；
第一部分分散剂占分散剂总质量的20％～50％，第二部分分散剂占分散剂的50％～80％，其中，负极粘结剂包括由式(I)所示的结构单元构成的聚合物：
Figure PCTCN2022137541-appb-000004
其中，第一部分分散剂的加入，能够对负极活性材料表面极性改性，以使负极活性材料与去离子水实现更好的浸润效果。第二部分分散剂的加入，使负极浆料中的各成分分散均匀，使负极浆料更加稳定。将第一部分分散剂和第二部分分散剂在分散剂中的质量占比调控在上述范围内，更利于发挥分散剂的上述作用。本申请对上述去离子水的含量没有特别限制，只要能够实现本申请目的即可。
本申请对上述各步骤中“搅拌”的方式、速度和时间均没有特别限制，只要能够实现本申请目的即可。
本申请对上述“调粘”的方式没有特别限制，只要使负极浆料的粘度调控在4000mPa·s～12000mPa·s范围内，实现本申请目的即可。
本申请对上述“真空除气”的方式和真空度没有特别限制，只要能够实现本申请目的即可。例如，真空度可以为-50KPa以上。
本申请的第二方面提供的负极浆料的制备方法，操作简单，原料易得，且原料安全环 保，减少了对环境和人员的危害，更适合行业内规模化应用。并且，制备方法中负极粘结剂的选用，更利于改善负极极片冷压粘辊的问题，进而更利于改善二次电池的循环性能和存储性能。
[负极极片]
本申请的第三方面提供一种负极极片，其包括负极集流体以及设置在负极集流体至少一个表面的负极膜层，作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。负极膜层由本申请的第一方面的负极浆料或者由本申请的第二方面的制备方法制备而成，负极膜层的涂布重量为130mg/1540.25mm 2～190mg/1540.25mm 2。将负极膜层的涂布重量调控在上述范围内，负极膜层在相同面积下具有合适含量的负极活性材料，能够使二次电池具有良好的能量密度。上述负极膜层由本申请的第一方面的负极浆料或者由本申请的第二方面的制备方法制备而成，更利于改善负极极片冷压粘辊的问题，进而更利于改善二次电池的循环性能和存储性能。
在一些实施方式中，负极膜层的压实密度为1.50g/cm 3～1.60g/cm 3。负极膜层的压实密度小于1.50g/cm 3时，负极活性材料各颗粒之间的间隙过大，负极活性材料各颗粒间的接触变差，将影响负极膜层的界面稳定性，进而影响二次电池的循环性能和存储性能；负极膜层的压实密度大于1.60g/cm 3时，负极活性材料颗粒的破碎风险增大，也将影响负极膜层的界面稳定性，进而影响二次电池的循环性能和存储性能。将负极膜层的压实密度调控在上述范围内，更利于改善二次电池的循环性能和存储性能。
在一些实施方式中，负极极片的内聚力为33.5N/m～80.1N/m。表明本申请的负极极片具有良好的内聚力，稳定了负极极片的结构，使负极极片冷压粘辊的问题得以改善，进而改善了二次电池的循环性能和存储性能。上述“内聚力”表示负极膜层内部的作用力，即负极膜层中负极活性材料与负极活性材料之间的作用力。
本申请对负极极片和负极膜层的厚度没有特别限制，只要能够实现本申请目的即可。优选地，在一些实施方式中，负极极片的厚度为113.5.4μm～172.4μm，负极膜层的单层厚度为52.8μm～82.2.μm。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、 聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，可以通过以下方式制备负极极片：将上述任一实施方式中的负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811))、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括 超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1，4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
[二次电池、电池模块、电池包和用电装置]
以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池，其包括上述任一实施方式所述的负极极片。本申请的二次电池可以指上述任一实施方式中所述的二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过 程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方 式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1-1
<负极浆料的制备>
将负极活性材料人造石墨、导电剂导电碳、第一部分分散剂羧甲基纤维素钠按照质量2375g、37.5gg、5g加入搅拌机进行干粉混合搅拌15min，其中搅拌公转25rpm，搅拌自转800rpm，制得均匀粉末；
在上述均匀粉末中加入1283g去离子水，搅拌60min，搅拌公转15rpm，制得第一均匀浆料；
将20g第二部分分散剂羧甲基纤维素钠和1217g的去离子水加入上述第一均匀浆料中搅拌65min，其中搅拌公转25rpm，搅拌自转1800rpm，制得第二均匀浆料；
在上述第二均匀浆料中加入62.5g本申请的负极粘结剂聚合物A，搅拌30min，其中搅拌公转25rpm，搅拌自转1200rpm，得到混合均匀的浆料；负极粘结剂的分子量为70W，基于负极浆料的总质量计，负极粘结剂的质量百分含量为2.5％；
在上一步的浆料中加入少量去离子水进行调粘，去离子水的加入方式采取少量多次加入，搅拌20min，其中搅拌公转10rpm，搅拌自转900rpm，制得粘度为8000mPa·s的浆料；
将搅拌机密封，开启真空除气至搅拌机内真空度达-50KPa，搅拌20min，其中搅拌公转10rpm，搅拌自转0rpm，最终制得固含量为50wt％的负极浆料。
<负极极片的制备>
将上述制得的负极浆料均匀涂覆在厚度为8μm的铜箔的一个表面上，涂布速度为30m/min，涂布质量为160mg/1540.25mm 2。98℃条件下烘干，冷压后得到负极膜层单层厚度为67.0μm的双面涂敷的负极极片，然后经过极耳成型、分切等工序得到规格为76mm×851mm负极极片。其中，冷压压力为50吨，冷压速度为40m/min，负极膜层的压实密度为1.55g/cm 3。
<正极极片的制备>
将正极活性材料LiNi 0.6Co 0.2Mn 0.2O 2、导电剂Super-P、粘结剂聚偏氟乙烯按照质量比96∶2∶2混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，在真空搅拌机作用下搅拌至体系呈均一状，得到固含量为70wt％的正极浆料。将正极浆料均匀涂覆在厚度为13μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极膜层单层厚度为55μm的双面涂敷的正极极片，然后经过极耳成型、分切等工序得到规格为74mm×867mm正极极片。
<电解液的制备>
在含水量小于10ppm的环境下，将溶剂碳酸亚乙酯、碳酸甲乙酯、碳酸二乙酯按照体积比1∶1∶1进行混合得到电解液溶剂，随后将锂盐LiPF 6溶解于混合后的溶剂中，配置成锂盐浓度为1mol/L的电解液。
<隔离膜的制备>
选择厚度为14μm的聚乙烯膜作为隔离膜。
<二次电池的制备>
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离作用，然后卷绕得到电极组件；将电极组件置于外包装壳中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到二次电池。
实施例1-2至实施例1-6
除了按照表1调整负极粘结剂的数均分子量以外，其余与实施例1-1相同，不同数均分子量的负极粘结剂由浙江中科立德新材料有限公司提供。
实施例2-1至实施例2-5
除了按照表2调整负极粘结剂的质量百分含量以外，其余与实施例1-1相同，其中，负极粘结剂的质量百分含量通过负极粘结剂质量的增减来调控，负极活性材料、导电剂和分散剂的质量与实施例1-1相同。
实施例3-1至实施例3-2
除了按照表3调整浆料的粘度以外，其余与实施例1-1相同，其中，浆料的粘度可以通过加去离子水调控。
实施例4-1至实施例4-3
除了按照表4调整负极膜层的涂布重量以外，其余与实施例1-1相同。
实施例4-4至实施例4-6
除了按照表4调整负极膜层的压实密度以外，其余与实施例1-1相同。
对比例1
除了按照表1选用丁苯橡胶(SBR)作为负极粘结剂以外，其余与实施例1-1相同。
相关参数测试
(1)冷压工艺中负极材料粘辊性能测试
将各实施例和对比例中的负极极片在冷压过程中收集刮刀从冷压辊表面刮下来的粉末的质量(g)。
用刮粉量的多少表征负极极片冷压粘辊问题，其中，刮粉量越多，表明负极极片冷压粘辊问题越严重。
(2)负极极片内聚力(负极膜层与负极集流体之间的粘结力)的测试
设备型号：众志检测拉力机(型号LXG2-LLCS-0009)，具体测试流程如下：
①取待测试负极极片，用刀片截取宽×长＝30mm×150mm的试样，将双面胶贴于钢板一端，胶带宽×长＝20mm×150mm。
②将①中截取的负极极片试样贴在双面胶上，测试面朝上。将宽度为20mm，长度为180mm的低粘绿胶带(型号：MD-XTG-620-2335L)平整粘在测试面表面，并用压辊沿同一方向滚压三次。
③打开上述拉力机电源，将未贴负极极片的钢板的另一端用下夹具固定，确保钢板与基台垂直放置，并保持钢板底端与基座平齐。将低粘绿胶带的一端向上翻折，用上夹具固定。
④先预拉5mm左右，然后将“力”和“位移”参数“清零”，使以上两个参数归零后，点击开始按钮开始测试，通过读取力和位移的数值，并将二者作比值得到内聚力的数值。然后 平行做三组，求平均值N1为内聚力。
(3)负极极片电阻的测试
将各实施例和对比例的负极极片用元能科技电池内阻测试仪(型号：BER1100)进行测试。负极极片的电阻测试过程为：沿着负极极片的纵向方向取4cm×25cm面积样品，缓慢打开压缩气阀，将内阻仪红黑测试线与极片电阻仪测试线连接，打开内阻仪、压力显示器电源，并连接电脑。将无尘纸浸润无水乙醇清洁上下Cu探针，拨动换向阀向下，两个Cu探针缓缓接触，将三联件上的黑色调压阀旋出将压力调节到压力显示器显示为0.4t，打开膜片电阻仪测试软件，将测试负极极片的集流体放在探针中间，先点击软件上的运行按钮然后向下拨动换向阀，过15s后自动采集一个数据，如此类同，直到测试20个点时换个组别，进行下一组别测试，最后将测试的结果求平均值。
(4)循环性能的测试
分别在25℃下，将各实施例和对比例制得的二次电池以1C恒流充电至4.2V、再以1C恒流放电至2.5V，此为一个充放电过程，此时的放电容量记为二次电池首次循环的放电容量C 1。将上述充放电过程循环400圈，第400圈循环结束后的放电容量记为第400圈循环的放电容量C 400。二次电池循环400圈的容量保持率(％)＝C 400/C 1×100％。
(5)存储性能的测试
将各实施例和对比例制得的二次电池以0.33C恒流满充至4.2V，4.2V恒压充电至0.05C截止，然后再以0.33V恒流放电至2.5V，此时的放电容量记为C 0，之后再以0.33C恒流满充至4.2V，4.2V恒压充电至0.05C截止，然后放置至恒温箱中，在25℃存储30天后取出，以0.33C放电至2.5V，再以0.33C恒流满充至4.2V，4.2V恒压充电至0.05C截止，然后再以0.33V恒流放电至2.5V，此时的放电容量记为C 30，锂离子电池存储30天后的容量保持率(％)＝C 30/C 0×100％。
上述各实施例和对比例的相关参数结果以及性能参数结果如下述表1～表4所示。
表1：实施例1-1至实施例1-6与对比例1的参数结果以及性能参数结果
Figure PCTCN2022137541-appb-000005
Figure PCTCN2022137541-appb-000006
注：表1中的“\”表示无相应参数结果。
表2：实施例1-1、实施例2-1至实施例2-5的参数结果以及性能参数结果
Figure PCTCN2022137541-appb-000007
表3：实施例1-1、实施例3-1至实施例3-2的参数结果和性能参数结果
Figure PCTCN2022137541-appb-000008
表4：实施例1-1、实施例4-1至实施例4-6的参数结果和性能参数结果
Figure PCTCN2022137541-appb-000009
根据上述结果可知，实施例1-1至实施例1-6的负极极片和二次电池，当选用本申请的负极粘结剂时，各实施例的负极极片具有较高的内聚力、较少的刮粉量，各实施例的二次 电池具有良好的循环性能和存储性能。而相对于此，对比例1中，选用本申请范围外的负极粘结剂时，二次电池的循环性能和存储性能未取得有效提高。
从实施例1-1至实施例1-6可以看出，当负极粘结剂的数均分子量在本申请范围内时，负极极片冷压粘辊现象得以改善，得到的二次电池具有更好的循环性能和存储性能。
从实施例1-1、实施例2-1至实施例2-5可以看出，当负极粘结剂在负极浆料中的质量百分含量在本申请范围内时，负极极片冷压粘辊现象得以改善，得到的二次电池具有更好的循环性能和存储性能。其中，实施例1-1中，负极粘结剂的质量百分含量为2.5％时，二次电池的循环性能和存储性能最好。实施例2-3中，负极粘结剂的质量百分含量高达3.5％时，二次电池也具有良好的循环性能和存储性能，但是由于负极粘结剂的含量较高，将会有多余的负极粘结剂自由移动，影响电解液在负极膜层中的浸润，使二次电池的循环性能和存储性能受到影响。
从实施例1-1、实施例3-1至实施例3-2可以看出，当负极浆料粘度在本申请范围内时，能够制备得到性能良好的负极极片和二次电池，其中，负极极片冷压粘辊现象得以改善，得到的二次电池具有更好的循环性能和存储性能。
从实施例1-1、实施例4-1至实施例4-6可以看出，当负极膜层的涂布重量和压实密度在本申请范围内时，能够制备得到性能良好的负极极片和二次电池，其中，负极极片冷压粘辊现象得以改善，得到的二次电池具有更好的循环性能和存储性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (13)

  1. 一种负极浆料，其特征在于，包括负极粘结剂，所述负极粘结剂包括由式(I)所示的结构单元构成的聚合物：
    Figure PCTCN2022137541-appb-100001
  2. 根据权利要求1所述的负极浆料，其特征在于，所述负极粘结剂的数均分子量为40W～120W，优选为70W～90W。
  3. 根据权利要求1或2所述的负极浆料，其特征在于，所述负极粘结剂的质量百分含量为1％～3.5％，优选为2％～3％，基于所述负极浆料的总质量计。
  4. 根据权利要求1～3中任一项所述的负极浆料，其特征在于，所述负极浆料包括负极活性材料、导电剂、分散剂和所述负极粘结剂，所述负极活性材料、所述导电剂、所述分散剂、所述负极粘结剂的质量比为(93.0～97.0)∶(1.0～2.0)∶(1.0～1.5)∶(1.0～3.5)，基于所述负极浆料的总质量计。
  5. 根据权利要求1～4中任一项所述的负极浆料，其特征在于，所述负极活性材料包括石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料和钛酸锂中的至少一种；可选地，
    所述石墨包括人造石墨和天然石墨中的至少一种；或
    所述硅基材料包括单质硅、硅氧化合物、硅碳复合物和硅合金中的至少一种；或
    所述锡基材料包括单质锡、锡氧化合物和锡合金中的至少一种。
  6. 根据权利要求1～5中任一项所述的负极浆料，其特征在于，所述负极浆料的粘度为4000mPa·s～12000mPa·s。
  7. 一种负极浆料的制备方法，其特征在于，包括以下步骤：
    将负极活性材料、导电剂、第一部分分散剂混合均匀，制得均匀粉末；
    在所述均匀粉末中加入去离子水，搅拌，制得第一均匀浆料；
    将第二部分分散剂和去离子水加入所述第一均匀浆料中，搅拌，制得第二均匀浆料；
    在所述第二均匀浆料中加入负极粘结剂，搅拌，调粘，真空除气，得到所述负极浆料；
    所述第一部分分散剂占所述分散剂总质量的20％～50％，所述第二部分分散剂占所述分 散剂的50％～80％，其中，所述负极粘结剂包括由式(I)所示的结构单元构成的聚合物：
    Figure PCTCN2022137541-appb-100002
  8. 一种负极极片，其特征在于，包括负极集流体以及设置在所述负极集流体至少一个表面的负极膜层，所述负极膜层由权利要求1～6中任一项所述的负极浆料或者由权利要求7所述的制备方法制备而成，所述负极膜层的涂布重量为130mg/1540.25mm 2～190mg/1540.25mm 2。
  9. 根据权利要求8所述的负极极片，其特征在于，所述负极膜层的压实密度为1.50g/cm 3～1.60g/cm 3。
  10. 一种二次电池，其特征在于，包括权利要求8或9所述的负极极片。
  11. 一种电池模块，其特征在于，包括权利要求10所述的二次电池。
  12. 一种电池包，其特征在于，包括权利要求11所述的电池模块。
  13. 一种用电装置，其特征在于，包括选自权利要求10所述的二次电池、权利要求11所述的电池模块或权利要求12所述的电池包中的至少一种。
PCT/CN2022/137541 2022-01-04 2022-12-08 负极浆料及其制备方法、负极极片和二次电池 WO2023130886A1 (zh)

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