WO2024098411A1 - 正极浆料的制备方法、正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极浆料的制备方法、正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2024098411A1
WO2024098411A1 PCT/CN2022/131511 CN2022131511W WO2024098411A1 WO 2024098411 A1 WO2024098411 A1 WO 2024098411A1 CN 2022131511 W CN2022131511 W CN 2022131511W WO 2024098411 A1 WO2024098411 A1 WO 2024098411A1
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positive electrode
stirring
binder
rpm
slurry
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PCT/CN2022/131511
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English (en)
French (fr)
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邢祁
孙成栋
刘会会
段连威
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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 CN202280092929.4A priority Critical patent/CN118805272A/zh
Priority to PCT/CN2022/131511 priority patent/WO2024098411A1/zh
Publication of WO2024098411A1 publication Critical patent/WO2024098411A1/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
    • 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 secondary batteries, and in particular to a method for preparing a positive electrode slurry, a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device.
  • secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • Electrode slurry is the basis for forming electrodes and is also the first step in the production of secondary batteries.
  • the characteristics of electrode slurry have a significant impact on subsequent electrode production and battery performance.
  • the positive electrode slurry is mainly a solid-liquid mixed system formed by positive electrode active materials, conductive agents, binders and solvents. This system is in a metastable state.
  • the slurry mixing process that is, the preparation method of the slurry, has a crucial influence on the dispersion, uniformity, stability and other properties of the slurry.
  • the slurry mixing process in the prior art is often a one-step method, in which the components in the positive electrode active slurry are directly mixed and stirred.
  • the prepared slurry has a high viscosity when shipped, and is prone to abnormal phenomena such as gelation and precipitation, which affects the subsequent coating, rolling process and the quality of the electrode sheet.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a method for preparing positive electrode slurry for secondary batteries, so as to reduce the shipping viscosity of the positive electrode slurry, broaden the process window for coating the positive electrode slurry, and improve the processing performance of the positive electrode slurry.
  • a first aspect of the present application provides a method for preparing a positive electrode slurry, which includes first stirring, second stirring, third stirring and fourth stirring;
  • the positive electrode active material, the conductive agent and the first binder are mixed and stirred to prepare a dry mixture;
  • the dry mixed material and the glue solution are mixed and stirred to prepare a primary slurry
  • the solvent is mixed and stirred with the primary slurry to prepare a positive electrode slurry
  • the weight average molecular weight of the polymer in the second binder is less than the weight average molecular weight of any polymer in the first binder.
  • the present application reduces the shipping viscosity of the positive electrode slurry and improves the processability of the positive electrode slurry by using a low molecular weight second binder and a relatively high molecular weight first binder in steps.
  • the method has wide versatility and can be applied to the preparation of slurry containing a new generation of high molecular weight polymer binders.
  • the positive electrode slurry prepared by the preparation method disclosed in the present application can effectively exert the characteristics of polyvinylidene fluoride binders with different molecular weights, and through the mutual coordination of large and small chain segments and the steric hindrance, the slurry has suitable viscosity and excellent processability.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 4 million.
  • Controlling the second binder to polyvinylidene fluoride with a weight average molecular weight not exceeding 4 million can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry, and enhance the bonding performance of the positive electrode sheet.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 2 million.
  • the second binder is polyvinylidene fluoride with a weight average molecular weight not exceeding 2 million, which can significantly reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry to a greater extent, improve the filtration performance of the positive electrode slurry, and enhance the bonding performance of the positive electrode sheet.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 1.5 million.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 1.5 million, which is beneficial to further reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, significantly slowing down the gelation of the positive electrode slurry and improving the filtration performance of the positive electrode slurry.
  • the first binder contains one or more polyvinylidene fluoride with a weight average molecular weight, and the first binder contains polyvinylidene fluoride with a weight average molecular weight of not less than 2 million.
  • the first binder comprises polyvinylidene fluoride having a weight average molecular weight of not less than 4,000,000.
  • the preparation method disclosed in the present application is universally applicable to low weight average molecular weight polyvinylidene fluoride binders and high weight average molecular weight polyvinylidene fluoride binders, so that the positive electrode slurry containing the binder with a weight average molecular weight of up to 8 million still has a suitable viscosity, and the pole piece prepared by the positive electrode slurry has excellent bonding performance and can meet the use requirements of the new generation of binders.
  • the mass content of the second binder is 30% to 50%, based on the total mass of the first binder and the second binder.
  • the mass content of the second binder is controlled to be 30% to 50%, based on the total mass of the first binder and the second binder, which can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry, and enhance the bonding performance of the positive electrode sheet, which is also beneficial to reduce production costs.
  • the revolution speed of the first stirring is 10 rpm to 20 rpm.
  • Controlling the revolution speed of the first stirring to 10 rpm to 20 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to reduce production costs.
  • the stirring time of the first stirring is 10 minutes to 25 minutes.
  • Controlling the stirring time of the first stirring to 10 minutes to 25 minutes can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to improving production efficiency and reducing production costs.
  • the second stirring revolution speed is 20 rpm to 30 rpm.
  • Controlling the revolution speed of the second stirring to 20 rpm to 30 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to reduce production costs.
  • the second stirring rotation speed is 1000 rpm to 1400 rpm.
  • Controlling the rotation speed of the second stirring to 1000 rpm to 1400 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to reduce production costs.
  • the second stirring time is 60 minutes to 90 minutes.
  • Controlling the stirring time of the second stirring to 60 minutes to 90 minutes can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to improving production efficiency and reducing production costs.
  • the third stirring has a stirring time of 60 to 90 minutes, a revolution speed of 20 to 30 rpm, and a rotation speed of 500 to 800 rpm.
  • the dry mixture prepared in the first stirring is added to the glue prepared in the second stirring and stirred slowly, so as to reduce the risk of agglomeration and gelation of the high molecular weight polymer in the first binder and improve the uniformity of kneading between the materials.
  • the fourth stirring process has an orbital speed of 20 to 30 rpm, an autorotational speed of 1000 to 1400 rpm, and a stirring time of 90 to 120 minutes.
  • the materials are stirred quickly at a relatively high stirring rotation speed to achieve full mixing and dispersion of the materials, so that the slurry meets the processing performance and electrical properties of lithium-ion batteries.
  • the solid content of the positive electrode slurry is 63% to 73%, and the initial viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s.
  • the slurry formed by the preparation method of the present application has a high solid content, suitable viscosity, and excellent processability.
  • the slurry can be directly used in the subsequent coating process, which can improve production efficiency.
  • the solvent used in the second stirring is the same as the solvent used in the fourth stirring. Based on the total mass of the conductive agent, the positive electrode active material, the first binder, and the second binder, the mass content of the solvent used in the second stirring is 35% to 40%, and the mass content of the solvent used in the fourth stirring is 5% to 10%.
  • the mass ratio of the positive electrode active material, the total mass of the first binder and the second binder, and the conductive agent is (82-95):(3-10):(2-8).
  • the positive electrode slurry within the above range has good processing performance and also enables the formed positive electrode plate to have excellent electrochemical performance.
  • the positive electrode active material is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.
  • the conductive agent is one or more of conductive carbon black, graphite, and carbon nanotubes.
  • the second aspect of the present application further provides a positive electrode slurry, which is prepared by the method for preparing the positive electrode slurry of the first aspect.
  • the viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s, and after standing for 24 hours, the viscosity of the positive electrode slurry does not exceed 48000 mPa ⁇ s.
  • the positive electrode slurry provided in the present application has suitable viscosity, excellent stability, and good processability.
  • the third aspect of the present application also provides a positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer is prepared from the positive electrode slurry prepared by the preparation method described in the first aspect.
  • the positive electrode sheet has high uniformity and bonding strength.
  • the bonding force per unit length between the positive electrode film layer and the positive electrode current collector is greater than 20 N/m.
  • the positive electrode film layer of the positive electrode sheet has a high bonding strength with the positive electrode current collector. During use, the positive electrode film layer is not easy to fall off from the positive electrode current collector, which helps to improve the cycle performance and safety of the battery.
  • the fourth aspect of the present application also provides a secondary battery, including a positive electrode plate, a separator, a negative electrode plate and an electrolyte, wherein the positive electrode plate is prepared by the positive electrode slurry prepared by the preparation method described in the first aspect or the positive electrode slurry described in the second aspect.
  • the secondary battery is any one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.
  • the fifth aspect of the present application also provides a battery module, comprising the secondary battery described in the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, comprising the secondary battery described in the fourth aspect of the present application or the battery module described in the fifth aspect of the present application.
  • the seventh aspect of the present application provides an electrical device comprising at least one selected from the secondary battery described in the fourth aspect of the present application, the battery module described in the fifth aspect of the present application, or the battery pack described in the sixth aspect of the present application.
  • FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG2 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG1 ;
  • FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG4 ;
  • FIG. 6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • range disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range.
  • the range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: 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).
  • the positive electrode slurry is mainly a solid-liquid mixed system formed by positive electrode active materials, conductive agents, binders and solvents.
  • slurry is often mixed through stirring, ball milling, ultrasound and other processes.
  • the slurry mixing process in the prior art is usually only applicable to slurry systems with fixed components, and has poor versatility. After the physical properties of the components in the slurry change, the slurry mixing process often needs to be adjusted. For example, the slurry mixing process in the prior art cannot be applied to high molecular weight binders.
  • the applicant found that high molecular weight binders can effectively reduce the amount of binder in the pole piece, which helps to increase the load of the pole piece.
  • the slurry containing high molecular weight binders often has a high viscosity when shipped, and the slurry is very easy to gel, which is difficult to meet the production needs of the pole piece.
  • the present application proposes a method for preparing a positive electrode slurry, including first stirring, second stirring, third stirring and fourth stirring; in the first stirring, the positive electrode active material, the conductive agent and the first binder are mixed and stirred to prepare a dry mixture; in the second stirring, the second binder is mixed and stirred with a solvent to prepare a glue solution; in the third stirring, the dry mixture and the glue solution are mixed and stirred to prepare a primary slurry; in the fourth stirring, the solvent and the primary slurry are mixed and stirred to prepare a positive electrode slurry; wherein the weight average molecular weight of the polymer in the second binder is less than the weight average molecular weight of any polymer in the first binder.
  • the positive electrode active material is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.
  • the conductive agent includes one or more of conductive carbon black, graphite, and carbon nanotubes.
  • the solvent is an aqueous medium, such as deionized water.
  • the solvent is an oily medium, selected from one or more of N-methyl-pyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide and 3-butoxy-N-methylpropionamide.
  • the positive electrode active material, the conductive agent and the first binder with a relatively high molecular weight are first stirred to obtain a dry mixture, and the first stirring causes the three to be mechanically riveted to form a tight entanglement; then the second binder is mixed with the solvent for a second stirring to prepare a glue solution, and the weight average molecular weight of the polymer in the second binder is less than the weight average molecular weight of any polymer in the binder.
  • the preparation of a glue solution with a lower viscosity is conducive to the subsequent dispersion of the dry mixture containing a large molecular weight polymer in the glue solution; then the dry mixture prepared by the first stirring is mixed with the glue solution for a third stirring to prepare a primary slurry, and the third stirring can effectively disperse the positive electrode active material and the conductive agent in the glue solution, and the binder in the glue solution can improve the stability of the slurry through electrostatic action and steric hindrance, and reduce the agglomeration and sedimentation of the positive electrode active material and the conductive agent; finally, the solvent is mixed with the primary slurry for a fourth stirring to obtain a positive electrode slurry, and the solvent added again in the fourth stirring can effectively adjust the shipping viscosity of the slurry to prevent the shipping viscosity from being too high and affecting the subsequent coating work.
  • the present application reduces the shipping viscosity of the positive electrode slurry and improves the processability of the positive electrode slurry by step-by-step mixing of a low molecular weight second binder with a relatively high molecular weight first binder.
  • the method has wide versatility and can be applied to the preparation of slurry containing a new generation of high molecular weight polymer binders.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight of no more than 4 million.
  • Controlling the second binder to polyvinylidene fluoride with a weight average molecular weight not exceeding 4 million can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry, and enhance the bonding performance of the positive electrode sheet.
  • the weight average molecular weight of the polyvinylidene fluoride in the second binder can be selected as any one of 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, 2,000,000, 2,500,000, 3,000,000, 3,500,000, and 4,000,000.
  • weight average molecular weight refers to the statistical average molecular weight of a polymer by mass, and the molecular weight averaged per unit weight.
  • the weight average molecular weight of a polymer can be tested by methods known in the art.
  • gel chromatography is used for testing, such as using a Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141). A polystyrene solution sample with a mass fraction of 3.0% is used as a reference, and a matching chromatographic column (oily: Styragel HT5DMF7.8 ⁇ 300mm+Styragel HT4) is selected.
  • a 3.0% polymer solution is prepared with purified N-methylpyrrolidone (NMP) solvent, and the prepared solution is allowed to stand for one day for use.
  • NMP N-methylpyrrolidone
  • tetrahydrofuran is first drawn with a syringe, rinsed, and repeated several times. Then 5 ml of the experimental solution is drawn, the air in the syringe is removed, and the needle tip is wiped dry. Finally, the sample solution is slowly injected into the injection port. After the indication is stable, the data is obtained and the weight average molecular weight is read.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 2 million.
  • Controlling the second binder to polyvinylidene fluoride with a weight average molecular weight not exceeding 2 million can further reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, and to a greater extent slow down the gelation of the positive electrode slurry and improve the filtration performance of the positive electrode slurry.
  • the second binder is polyvinylidene fluoride having a weight average molecular weight not exceeding 1.5 million.
  • Controlling the second binder to polyvinylidene fluoride with a weight average molecular weight not exceeding 1.5 million can further reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, greatly slowing down the gelation of the positive electrode slurry and improving the filtration performance of the positive electrode slurry.
  • the first binder contains one or more polyvinylidene fluoride with a weight average molecular weight, and the first binder contains a polyvinylidene fluoride with a weight average molecular weight of not less than 2 million. In some embodiments, the first binder contains a polyvinylidene fluoride with a weight average molecular weight, and its weight average molecular weight is not less than 2 million. In some embodiments, the first binder contains two or more polyvinylidene fluoride with different weight average molecular weights, and the weight average molecular weight of at least one polyvinylidene fluoride is not less than 2 million. In some embodiments, the first binder contains a polyvinylidene fluoride with a weight average molecular weight of not less than 4 million.
  • the weight average molecular weight of the polyvinylidene fluoride having a weight average molecular weight of not less than 2 million can be selected as any one or more of 2 million, 2.5 million, 3 million, 3.5 million, 4 million, 4.5 million, 5 million, 5.5 million, 6 million, 6.5 million, 7 million, 7.5 million, 8 million, 8.5 million, and 9 million.
  • the preparation method of positive electrode slurry in the prior art has poor compatibility, cannot meet the preparation requirements of binders with different molecular weights, and cannot perform high-quality slurrying of a new generation of high molecular weight polymer binders.
  • the preparation method disclosed in the present application is universal and applicable to binders with different weight average molecular weights, and can especially meet the preparation requirements of a new generation of high molecular weight polymer binders, effectively reduce the shipping viscosity of positive electrode slurry and the viscosity after standing for 24 hours, and help improve the coating and processability of positive electrode slurry.
  • the mass content of the second binder is 30% to 50%, based on the total mass of the first binder and the second binder. In some embodiments, the mass content of the second binder can be any one of 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, and 50%.
  • the mass content of the second binder is controlled to be 30% to 50%, which can not only give full play to the strong bonding performance of the high molecular weight polymer in the first binder and improve the bonding performance of the positive electrode sheet, but also ensure the processing performance of the positive electrode slurry, ensuring that it has a lower shipping viscosity, viscosity after standing for 24 hours, and excellent anti-gel performance and filterability.
  • the rotation speed of the first stirring is 0. In some embodiments, the revolution speed of the first stirring is 10 rpm to 20 rpm. In some embodiments, the revolution speed of the first stirring can be selected from any one of 10 rpm, 11 rpm, 12 rpm, 13 rpm, 14 rpm, 15 rpm, 16 rpm, 17 rpm, 18 rpm, 19 rpm, and 20 rpm.
  • rotational speed refers to the speed at which the agitator rotates about its own axis.
  • bital speed refers to the speed at which the agitator rotates around the vessel containing the material.
  • the stirring device is a planetary mixer.
  • the working principle of the planetary mixer is that after the mixer is started, the planetary frame rotates, driving the stirring shaft in the box to rotate, and the stirring shaft rotates at high speed while revolving around the axis of the barrel, so that the material is subjected to strong shearing and kneading. It can be understood that the preparation method provided in this application is applicable to any type of planetary mixer.
  • Controlling the rotation speed of the first stirring to 0 can reduce the damage to the materials during the dry mixing process. Controlling the revolution speed of the first stirring to 10 rpm to 20 rpm can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, improve the filtration performance of the positive electrode slurry, enhance the bonding performance of the positive electrode sheet, and also help reduce production costs.
  • the stirring time of the first stirring is 10 minutes to 25 minutes. In some embodiments, the stirring time of the first stirring can be selected from any one of 10 minutes, 12 minutes, 14 minutes, 15 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, and 25 minutes.
  • Controlling the stirring time of the first stirring to 10 minutes to 25 minutes can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to improving production efficiency and reducing production costs.
  • the revolution speed of the second stirring is 20 rpm to 30 rpm. In some embodiments, the revolution speed of the second stirring can be selected from any one of 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm, and 30 rpm.
  • Controlling the revolution speed of the second stirring to 20 rpm to 30 rpm can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and it is also beneficial to reduce production costs.
  • the second stirring rotation speed is 1000 rpm to 1400 rpm. In some embodiments, the second stirring rotation speed can be selected from any one of 1000 rpm, 1050 rpm, 1100 rpm, 1150 rpm, 1200 rpm, 1250 rpm, 1300 rpm, 1350 rpm, and 1400 rpm.
  • Controlling the rotation speed of the second stirring to 1000 rpm to 1400 rpm can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to reduce production costs.
  • the stirring time of the second stirring is 60 minutes to 90 minutes. In some embodiments, the stirring time of the second stirring can be selected from any one of 60 minutes, 62 minutes, 65 minutes, 68 minutes, 70 minutes, 73 minutes, 75 minutes, 77 minutes, 80 minutes, 85 minutes, and 90 minutes.
  • Controlling the stirring time of the second stirring to 60 minutes to 90 minutes can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet, and is also beneficial to improving production efficiency and reducing production costs.
  • the stirring time of the third stirring is 60 minutes to 90 minutes, the revolution speed is 20 rpm to 30 rpm, and the rotation speed is 500 rpm to 800 rpm.
  • the stirring time of the third stirring can be selected as any one of 60 minutes, 70 minutes, 80 minutes, and 90 minutes.
  • the revolution speed can be selected as any one of 20 rev/min, 25 rev/min, and 30 rev/min.
  • the rotation speed can be selected as any one of 500 rev/min, 550 rev/min, 600 rev/min, 650 rev/min, 700 rev/min, 750 rev/min, and 800 rev/min.
  • the dry blend prepared in the first stirring is added to the glue prepared in the second stirring and stirred slowly, so as to reduce the risk of agglomeration and gelation of the high molecular weight polymer in the first binder and improve the uniformity of kneading between the materials.
  • the fourth stirring process has an orbital speed of 20 to 30 rpm, a rotation speed of 1000 to 1400 rpm, and a stirring time of 90 to 120 minutes.
  • the revolution speed of the 4th stirring can be optionally 20 rev/min, 25 rev/min or 30 rev/min.
  • the rotation speed can be optionally 1000 rev/min, 1100 rev/min, 1200 rev/min, 1300 rev/min or 1400 rev/min.
  • the mixing time can be optionally 90 minutes, 100 minutes, 110 minutes or 120 minutes.
  • the materials are stirred quickly at a relatively high stirring rotation speed to achieve sufficient mixing and dispersion of the materials, so that the slurry meets the processing performance and electrical properties of lithium-ion batteries.
  • the solid content of the positive electrode slurry is 63% to 73%, and the initial viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s.
  • the solid content of the positive electrode slurry is 63% to 73%
  • the initial viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s.
  • the initial viscosity of the positive electrode slurry can be selected from 8000 mPa.s, 9000 mPa.s, 10000 mPa.s, 11000 mPa.s, 12000 mPa.s, 13000 mPa.s, 14000 mPa.s, 15000 mPa.s, 16000 mPa.s, 17000 mPa.s, 18000 mPa.s, 19000 mPa.s, 20000 mPa.s, 2200 Any one of 0mPa.s, 23000mPa.s, 24000mPa.s, 25000mPa.s, 26000mPa.s, 27000mPa.s, 28000mPa.s,
  • the initial viscosity of the positive electrode slurry refers to the shipping viscosity of the positive electrode slurry.
  • the viscosity of the positive electrode slurry when it is prepared and shipped is recorded as the initial viscosity of the positive electrode slurry.
  • the viscosity of the positive electrode slurry can be tested by methods known in the art, such as using a rotating viscometer to measure the viscosity of the slurry.
  • a rotating viscometer to measure the viscosity of the slurry.
  • Select a suitable rotor fix the viscometer rotor, place the slurry under the viscometer rotor, and the slurry just submerges the scale line of the rotor.
  • the initial viscosity of the positive electrode slurry with a solid content of 63% to 73% is 8000 mPa ⁇ s to 35000 mPa ⁇ s.
  • the positive electrode slurry has good coating and processability, and widens the coating process window.
  • the solvent used in the second stirring is the same as the solvent used in the fourth stirring. Based on the total mass of the conductive agent, the positive electrode active material, the first binder, and the second binder, the mass content of the solvent used in the second stirring is 35% to 40%, and the mass content of the solvent used in the fourth stirring is 5% to 10%.
  • the mass content of the solvent used in the second stirring can be selected from 35%, 36%, 37%, 38%, 39% or 40%
  • the mass content of the solvent used in the fourth stirring can be selected from 5%, 6%, 7%, 8%, 9% or 10%, based on the total mass of the conductive agent, the positive electrode active material, the first binder, and the second binder.
  • the mass ratio of the total mass of the positive electrode active material, the first binder and the second binder, and the mass ratio of the conductive agent is (82-95): (3-10): (2-8).
  • the mass ratio of the total mass of the positive electrode active material, the first binder and the second binder, and the mass ratio of the conductive agent can be any one of 95:3:2, 94:4:2, 93:5:2, 92:5:3, 91:6:3, 90:8:2, 90:5:5, 90:7:2, 88:8:4, 88:5:7, and 82:10:8.
  • the positive electrode slurry within the above range has good processing performance and also enables the formed positive electrode plate to have excellent electrochemical performance.
  • the positive electrode active material is one or more of lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.
  • the positive electrode active material enables the battery to have a high energy density, which is beneficial to improving the cycle performance of the battery.
  • the conductive agent is one or more of conductive carbon black, graphite, and carbon nanotubes.
  • the above conductive agent is beneficial to improving the conductivity of the battery.
  • the present application provides a positive electrode slurry, which is prepared by a preparation method in any embodiment of the present application.
  • the solid content of the positive electrode slurry is 63% to 73%, and the initial viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s, and after standing for 24 hours, the viscosity of the positive electrode slurry does not exceed 48000 mPa ⁇ s.
  • the initial viscosity of the positive electrode slurry can be 8000 mPa.s, 9000 mPa.s, 10000 mPa.s, 11000 mPa.s, 12000 mPa.s, 13000 mPa.s, 14000 mPa.s, 15000 mPa.s, 16000 mPa.s, Any one of 17000mPa.s, 18000mPa.s, 19000mPa.s, 20000mPa.s, 22000mPa.s, 23000mPa.s, 24000mPa.s, 25000mPa.s, 26000mPa.s, 27000mPa.s, 28000mPa.s, 29000mPa.s, 30000mPa.s, 30500mPa.s, 31000mPa.s, 32000mPa.s, 33000mPa.s, 34000mPa.s, and 35000mPa.
  • the viscosity of the positive electrode slurry may be 8000mPa.s, 9000mPa.s, 10000mPa.s, 11000mPa.s, 12000mPa.s, 13000mPa.s, 14000mPa.s, 15000mPa.s, 16000mPa.s, 17000mPa.s, 18000mPa.s, 19000mPa.s, 20000mPa.s, 22000mPa.s, 23000mPa.s, 24000mPa.s.
  • the positive electrode slurry has suitable viscosity, excellent stability, and good processability.
  • the present application provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer is prepared by a preparation method in any embodiment of the present application.
  • the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • 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.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • 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.
  • 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 LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate 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 referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the bonding force per unit length between the positive electrode film layer and the positive electrode current collector is greater than 20 N/m. In some embodiments, the bonding force per unit length between the positive electrode film layer and the positive electrode current collector is 20 N/m to 30 N/m, which can be selected as. In some embodiments, the bonding force per unit length between the positive electrode film layer and the positive electrode current collector can be selected as any one of 20 N/m, 20.5 N/m, 21 N/m, 21.5 N/m, 22 N/m, 22.5 N/m, 23 N/m, 23.5 N/m, 24 N/m, 24.5 N/m, 25 N/m, 27 N/m, and 30 N/m.
  • the bonding force is mainly used to characterize the bonding strength between the film layer prepared by the positive electrode slurry in the positive electrode plate and the current collector, which can be tested by any known method.
  • the test of the bonding force per unit length between the positive electrode film layer and the positive electrode current collector can be tested by methods known in the art, such as referring to GB-T2790-1995 national standard "Adhesive 180° Peel Strength Test Method", the bonding force test process of the embodiments and comparative examples of this application is as follows: Use a blade to cut a sample with a width of 30mm and a length of 100-160mm, and stick a special double-sided tape on a steel plate with a width of 20mm and a length of 90-150mm.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper 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.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • 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, lithium titanate, etc.
  • 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.
  • the present application is not limited to these materials, and other traditional 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.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • 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.
  • 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, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG1 is a secondary battery 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the 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.
  • secondary batteries may be assembled into a battery module.
  • the number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG3 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. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a housing space, and the plurality of secondary batteries 5 are housed in the housing space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • FIG4 and FIG5 are battery packs 1 as an example.
  • 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, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical 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 for the electrical device, or as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG6 is an example of an electric 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 mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • weighing raw materials weighing raw materials according to the positive electrode slurry ratio, the mass ratio of positive electrode active material: first binder: second binder: conductive agent is 95:1.5:1.5:2, wherein the mass of the positive electrode active material is 1200 kg, the positive electrode active material is lithium iron phosphate, the first binder is polyvinylidene fluoride with a weight average molecular weight of 2 million, the second binder is polyvinylidene fluoride with a weight average molecular weight of 1 million, and the conductive agent is conductive carbon black;
  • First stirring lithium iron phosphate, conductive carbon black and the first binder are mixed and stirred sufficiently at an orbital speed of 15 rpm, a rotation speed of 0, and a stirring time of 15 minutes to obtain a dry mixture;
  • Second stirring the second binder is mixed with N-methylpyrrolidone (NMP) solvent and stirred thoroughly.
  • NMP N-methylpyrrolidone
  • the mass of NMP solvent added in the second stirring is 35% of the total mass of the positive electrode active material, the first binder, the second binder and the conductive agent.
  • the revolution speed is 25 rpm, the rotation speed is 1200 rpm, and the stirring time is 60 minutes to obtain a glue solution.
  • Fourth stirring adding NMP solvent to the primary slurry, wherein the mass of the NMP solvent added in the fourth stirring is 10% of the total mass of the positive electrode active material, the first binder, the second binder and the conductive agent, the revolution speed is 25 rpm, the rotation speed is 1200 rpm, the stirring time is 110 minutes, and a positive electrode slurry with a solid content of 68% ⁇ 5% is obtained.
  • the positive electrode slurry prepared in Example 1 was evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain a positive electrode sheet.
  • the preparation method is basically the same as that of Example 1, except that the first binder in the first stirring is adjusted to polyvinylidene fluoride with a weight average molecular weight of 4 million and polyvinylidene fluoride with a weight average molecular weight of 8 million, respectively.
  • the first binder in the first stirring is adjusted to polyvinylidene fluoride with a weight average molecular weight of 4 million and polyvinylidene fluoride with a weight average molecular weight of 8 million, respectively.
  • Table 1 For specific parameters, see Table 1.
  • the preparation method is basically the same as that in Example 3, except that the second binder in the second stirring is adjusted to polyvinylidene fluoride with a weight average molecular weight of 4 million, polyvinylidene fluoride with a weight average molecular weight of 3 million, polyvinylidene fluoride with a weight average molecular weight of 2 million, polyvinylidene fluoride with a weight average molecular weight of 1.5 million, and polyvinylidene fluoride with a weight average molecular weight of 500,000, respectively.
  • Table 1 For specific parameters, see Table 1.
  • the preparation method is basically the same as that of Example 3, except that the mass ratio of the first binder to the second binder is adjusted. For specific parameters, see Table 1.
  • the preparation method is basically the same as that in Example 1, except that the first binder is adjusted to a composition.
  • the first binder is a composition of polyvinylidene fluoride with a weight average molecular weight of 2 million and polyvinylidene fluoride with a weight average molecular weight of 4 million, wherein the polyvinylidene fluoride with a weight average molecular weight of 2 million in the first binder accounts for 30% of the total amount of the binder, the polyvinylidene fluoride with a weight average molecular weight of 4 million accounts for 40% of the total amount of the binder, and the polyvinylidene fluoride with a weight average molecular weight of 1 million in the second binder accounts for 30% of the total amount of the binder.
  • Table 1 For specific parameters in other embodiments, see Table 1.
  • the preparation method is basically the same as that of Example 3, except that the stirring parameters of the first stirring and the second stirring are adjusted. For specific parameters, see Table 1.
  • weighing raw materials weighing raw materials according to the positive electrode slurry ratio, the mass ratio of positive electrode active material: binder: conductive agent is 95:3:2, wherein the mass of the positive electrode active material is 1200kg, the positive electrode active material is lithium iron phosphate, the binder is polyvinylidene fluoride with a weight average molecular weight of 2 million, and the conductive agent is conductive carbon black;
  • First stirring mix lithium iron phosphate and conductive carbon black, stir them thoroughly, the revolution speed is 15 rpm, the rotation speed is 0, and the stirring time is 15 minutes to obtain a dry mixture;
  • Second stirring Mix the binder and NMP solvent and stir them thoroughly.
  • the mass of the added solvent is 35% of the total mass of the positive electrode active material, the binder and the conductive agent.
  • the revolution speed is 25 rpm, the rotation speed is 1200 rpm, and the stirring time is 60 minutes to obtain a glue solution.
  • Third stirring adding the dry mixture prepared by the first stirring to the glue prepared by the second stirring, stirring fully, with a revolution speed of 25 rpm, a rotation speed of 600 rpm, and a stirring time of 60 minutes to obtain a primary slurry;
  • Fourth stirring add NMP solvent to the primary slurry, the mass of the added solvent is 10% of the total mass of the positive electrode active material, binder and conductive agent, the revolution speed is 25 rpm, the rotation speed is 1200 rpm, the stirring time is 110 minutes, and a positive electrode slurry with a solid content of 68% ⁇ 5% is obtained.
  • a Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141) was used.
  • a polystyrene solution sample with a mass fraction of 3.0% was used as a reference, and a matching chromatographic column (oily: Styragel HT5DMF7.8 ⁇ 300mm+Styragel HT4) was selected.
  • a 3.0% polymer solution was prepared with purified N-methylpyrrolidone (NMP) solvent, and the prepared solution was allowed to stand for one day for use. During the test, tetrahydrofuran was first drawn with a syringe and rinsed, and repeated several times.
  • NMP N-methylpyrrolidone
  • the slurry was retested for viscosity, and the viscosity of the slurry was measured using a rotating viscometer. Select a suitable rotor, fix the viscometer rotor, and place the slurry under the viscometer rotor. The slurry just submerges the scale line of the rotor. Instrument model: Shanghai Fangrui NDJ-5S, rotor: 63# (2000-10000mPa.s), 64# (10000-50000mPa.s), speed: 12 rpm, test temperature: 25°C, test time: 5 minutes, and read the data after the display is stable.
  • a steel ruler was used to pick up the slurry in the beaker, and the gel state of the slurry was determined based on the flow state of the slurry.
  • the gel-free state means that the slurry flows naturally and continuously, and the slurry flows on the surface of the steel ruler without agglomeration.
  • the slight gel state is that the slurry flows naturally and continuously, but the fluid is thin, and the slurry is basically spread evenly on the surface of the steel ruler with slight small pieces;
  • the medium gel state is that the slurry drips naturally and intermittently; it does not flow continuously, the slurry cannot be spread evenly on the surface of the steel ruler, and there are obvious block agglomerations;
  • Severe gel state means that the slurry cannot flow down as a stream, falls off in lumps or remains directly on the steel ruler and cannot flow down.
  • the adhesion test process of the embodiments and comparative examples of the present application is as follows: Use a blade to cut a sample with a width of 30mm and a length of 100-160mm, and stick the special double-sided tape on the steel plate, the tape width is 20mm, and the length is 90-150mm. Stick the coated surface of the electrode sample cut earlier on the double-sided tape, and then roll it three times in the same direction with a 2kg roller. Fix a paper tape with a width equal to the width of the electrode and a length of 250mm on the electrode collector and fix it with wrinkled glue.
  • the indicator light is on, adjust the limit block to the appropriate position, and fix the end of the steel plate without the electrode with the lower clamp. Fold the paper tape upwards and fix it with the upper clamp, and use the "up” and “down” buttons on the manual controller attached to the tensile machine to adjust the position of the upper clamp. Then test and read the value, the tensile speed is 50mm/min. The force when the electrode is under force balance divided by the width of the tape is taken as the bonding force of the electrode per unit length to characterize the bonding strength between the positive electrode film layer and the current collector.
  • the positive electrode slurries in Examples 1 to 44 are all prepared by the slurry preparation method disclosed in this application, and all include the first stirring, the second stirring, the third stirring and the fourth stirring; in the first stirring, the positive electrode active material lithium iron phosphate, the conductive agent conductive carbon black and the first binder polyvinylidene fluoride are mixed and stirred to prepare a dry blend; in the second stirring, the second binder polyvinylidene fluoride is mixed and stirred with the NMP solvent to prepare a glue; in the third stirring, the dry blend is mixed and stirred with the glue to prepare a primary slurry; in the fourth stirring, the NMP solvent is mixed and stirred with the primary slurry to prepare a positive electrode slurry; wherein the weight average molecular weight of the polyvinylidene fluoride in the second binder is less than the weight average molecular weight of any polyvinylidene fluoride in the first binder.
  • controlling the second binder to be polyvinylidene fluoride with a weight average molecular weight of no more than 4 million can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry, and enhance the bonding performance of the positive electrode sheet.
  • controlling the second binder to be polyvinylidene fluoride with a weight average molecular weight of no more than 2 million can further reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry and improve the filtration performance of the positive electrode slurry to a greater extent.
  • Example 6 From the comparison of Examples 3, 7 to 8 with Example 6, it can be seen that controlling the second binder to be polyvinylidene fluoride with a weight average molecular weight of no more than 1.5 million can further reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, greatly slow down the gelation of the positive electrode slurry and improve the filtration performance of the positive electrode slurry.
  • the preparation method is applicable to the first binder containing one or more polyvinylidene fluoride with a weight average molecular weight, and is particularly applicable to the first binder containing polyvinylidene fluoride with a weight average molecular weight of not less than 2 million.
  • Example 12 From the comparison between Example 3, Examples 10-11 and Example 9, Example 12, it can be seen that based on the total mass of the first binder and the second binder, the mass content of the second binder is controlled to be 30%-50%, which can not only give full play to the strong bonding performance of the high molecular weight polymer in the first binder and improve the bonding performance of the positive electrode sheet, but also ensure the processing performance of the positive electrode slurry, ensuring that it has a lower shipping viscosity, viscosity after standing for 24 hours, and excellent anti-gel performance and filterability.
  • Example 3 From the comparison between Example 3, Examples 18 to 19 and Example 17, it can be seen that controlling the revolution speed of the first stirring to 10 rpm to 20 rpm can effectively reduce the shipping viscosity of the positive electrode slurry and the viscosity after standing for 24 hours, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 18 to 19 and Example 20, it can be seen that controlling the revolution speed of the first stirring to 10 rpm to 20 rpm can reduce the production cost while ensuring the bonding performance and filtration performance of the positive electrode slurry and the bonding performance of the positive electrode sheet.
  • Example 3 Examples 22-23 and Example 21 From the comparison between Example 3, Examples 22-23 and Example 21, it can be seen that controlling the stirring time of the first stirring to 10 minutes to 25 minutes can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 22-23 and Example 24, it can be seen that controlling the stirring time of the first stirring to 10 minutes to 25 minutes can improve the production efficiency and production cost while ensuring the bonding performance and filtration performance of the positive electrode slurry and the bonding performance of the positive electrode sheet.
  • Example 3 From the comparison between Example 3, Examples 26 to 27 and Example 25, it can be seen that controlling the revolution speed of the second stirring to 20 rpm to 30 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 26 to 27 and Example 28, it can be seen that controlling the revolution speed of the second stirring to 20 rpm to 30 rpm can reduce the production cost while ensuring the bonding performance and filtration performance of the positive electrode slurry, as well as the bonding performance of the positive electrode sheet.
  • Example 3 From the comparison between Example 3, Examples 30-31 and Example 29, it can be seen that controlling the rotation speed of the second stirring to 1000 rpm to 1400 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 30-31 and Example 32, it can be seen that controlling the rotation speed of the second stirring to 1000 rpm to 1400 rpm can slow down the positive electrode slurry and reduce the production cost under the premise of ensuring the bonding performance and filtration performance of the positive electrode slurry and the bonding performance of the positive electrode sheet.
  • Example 3 From the comparison between Example 3, Examples 34 to 35 and Example 33, it can be seen that controlling the stirring time of the second stirring to 60 minutes to 90 minutes can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 34 to 35 and Example 36, it can be seen that controlling the stirring time of the second stirring to 60 minutes to 90 minutes can improve production efficiency and reduce production costs while ensuring the bonding performance and filtration performance of the positive electrode slurry and the bonding performance of the positive electrode sheet.
  • Example 3 Examples 38 to 39 and Example 37, it can be seen that controlling the rotation speed of the third stirring to 500 rpm to 800 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 38 to 39 and Example 40, it can be seen that controlling the rotation speed of the third stirring to 500 rpm to 800 rpm can reduce the cost while ensuring the bonding performance, filtration performance of the positive electrode slurry and bonding performance of the positive electrode sheet.
  • Example 3 From the comparison between Example 3, Examples 42 to 43 and Example 41, it can be seen that controlling the rotation speed of the fourth stirring to 1000 rpm to 1400 rpm can effectively reduce the shipping viscosity of the positive electrode slurry, the viscosity after standing for 24 hours, slow down the gelation of the positive electrode slurry, improve the filtration performance of the positive electrode slurry and enhance the bonding performance of the positive electrode sheet; from the comparison between Example 3, Examples 42 to 43 and Example 44, it can be seen that controlling the rotation speed of the fourth stirring to 1000 rpm to 1400 rpm can reduce the production cost while ensuring the bonding performance, filtration performance of the positive electrode slurry and the bonding performance of the positive electrode sheet.
  • the solid content of the positive electrode slurry disclosed in the present application is 63% to 73%, and the viscosity of the positive electrode slurry is 8000 mPa ⁇ s to 35000 mPa ⁇ s, and the positive electrode slurry has good coating and processability.

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Abstract

本申请提供了一种正极浆料的制备方法、正极极片、二次电池、电池模块、电池包和用电装置。该制备方法包括第一搅拌、第二搅拌、第三搅拌和第四搅拌；第一搅拌中，将正极活性材料、导电剂与第一粘结剂混合搅拌，制备干混料；第二搅拌中，将第二粘结剂与溶剂混合搅拌，制备胶液；第三搅拌中，将干混料与胶液混合搅拌，制备初级浆料；第四搅拌中，将溶剂与初级浆料混合搅拌，制备正极浆料；其中，第二粘结剂中聚合物的重均分子量小于第一粘结剂中任意聚合物的重均分子量。

Description

正极浆料的制备方法、正极极片、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种正极浆料的制备方法、正极极片、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。
电极浆料是成型电极的基础，也是二次电池生产的第一道工序。电极浆料的特性对后续的电极生产、电池性能都有显著的影响。正极浆料主要是由正极活性材料、导电剂、粘结剂和溶剂形成的固-液相混合体系。该体系处于一种亚稳定状态，合浆工艺，也就是浆料的制备方法对浆料的分散性、均匀性、稳定性等性能有着至关重要的影响。现有技术中的合浆工艺常为一步法，将正极活性浆料中的各组分直接混合搅拌即得，制备的浆料出货粘度大，容易出现凝胶、沉淀等异常现象，影响后续的涂布、辊压工艺以及极片的品质。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种二次电池正极浆料的制备方法，以降低正极浆料的出货粘度，拓宽正极浆料涂布的工艺窗口，提高正极浆料的加工性能。
本申请的第一方面提供了一种正极浆料的制备方法，其包括第一搅拌、第二搅拌、第三搅拌和第四搅拌；
所述第一搅拌中，将正极活性材料、导电剂与第一粘结剂混合搅拌，制备干混料；
所述第二搅拌中，将第二粘结剂与溶剂混合搅拌，制备胶液；
所述第三搅拌中，将所述干混料与所述胶液混合搅拌，制备初级浆料；
所述第四搅拌中，将溶剂与所述初级浆料混合搅拌，制备正极浆料；
其中，所述第二粘结剂中聚合物的重均分子量小于所述第一粘结剂中任意聚合物的重均分子量。
本申请通过将低分子量的第二粘结剂与相对高分子量的第一粘结剂分步搭配使用，降低了正极浆料的出货粘度，提高了正极浆料的可加工性，且该方法具有广泛的通用性，能够适用于包含新一代高分子量聚合物粘结剂的浆料制备。
本申请公开的制备方法制备的正极浆料能够有效发挥不同分子量的聚偏氟乙烯粘结剂的特性，通过大小链段的相互配合和空间位阻作用，使得浆料具有适宜的粘度和优异的可加工性。
在任意实施方式中，所述第二粘结剂为重均分子量不超过400万的聚偏氟乙烯。
控制第二粘结剂为重均分子量不超过400万的聚偏氟乙烯，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能、以及提升正极极片的粘结性能。
在任意实施方式中，所述第二粘结剂为重均分子量不超过200万的聚偏氟乙烯。
所述第二粘结剂为重均分子量不超过200万的聚偏氟乙烯，可以显著降低正极浆料的出货粘度和静置24小时后的粘度，更大程度上减缓正极浆料凝胶、改善正极浆料的过滤性能、以及提升正极极片的粘结性能。
在任意实施方式中，所述第二粘结剂为重均分子量不超过150万的聚偏氟乙烯。
所述第二粘结剂为重均分子量不超过150万的聚偏氟乙烯，有利于更进一步降低正极浆料的出货粘度和静置24小时后的粘度，大 幅减缓正极浆料凝胶和改善正极浆料的过滤性能。
在任意实施方式中，所述第一粘结剂中包含一种或多种重均分子量的聚偏氟乙烯，且所述第一粘结剂中包含重均分子量不小于200万的聚偏氟乙烯。
在任意实施方式中，所述第一粘结剂中包含重均分子量不小于400万的聚偏氟乙烯。
本申请公开的制备方法对低重均分子量聚偏氟乙烯粘结剂和高重均分子量聚偏氟乙烯粘结剂具有普适性，使得包含重均分子量高达800万粘结剂的正极浆料依然具有适宜的粘度，并且该正极浆料制备的极片具有优良的粘结性能，能够满足新一代粘结剂的使用需求。
在任意实施方式中，所述第二粘结剂的质量含量为30％～50％，基于所述第一粘结剂和所述第二粘结剂的总质量计。
控制所述第二粘结剂的质量含量为30％～50％，基于所述第一粘结剂和所述第二粘结剂的总质量计，可以有效降低正极浆料的出货粘度、静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能、以及提升正极极片的粘结性能，同时也有利于降低生产成本。
在任意实施方式中，所述第一搅拌的公转速度为10转/分钟～20转/分钟。
控制所述第一搅拌的公转速度为10转/分钟～20转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于降低生产成本。
在任意实施方式中，所述第一搅拌的搅拌时间为10分钟～25分钟。
控制所述第一搅拌的搅拌时间为10分钟～25分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于提高生产效率、降低生产成本。
在任意实施方式中，所述第二搅拌的公转速度为20转/分钟～30转/分钟。
控制所述第二搅拌的公转速度为20转/分钟～30转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于降低生产成本。
在任意实施方式中，所述第二搅拌的自转速度为1000转/分钟～1400转/分钟。
控制所述第二搅拌的自转速度为1000转/分钟～1400转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于降低生产成本。
在任意实施方式中，所述第二搅拌的搅拌时间为60分钟～90分钟。
控制所述第二搅拌的搅拌时间为60分钟～90分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于提高生产效率，降低生产成本。
在任意实施方式中，所述第三搅拌的搅拌时间为60分钟～90分钟，公转速度为20转/分钟～30转/分钟，自转速度为500转/分钟～800转/分钟。
在所述第三搅拌中通过将所述第一搅拌中制备的干混料加入所述第二搅拌中制备的胶液中慢搅，降低所述第一粘结剂中高分子量聚合物团聚凝胶的风险，提高物料间捏合的均匀性。
在任意实施方式中，所述第四搅拌的公转速度为20转/分钟～30转/分钟，自转速度为1000转/分钟～1400转/分钟，搅拌时间为90分钟～120分钟。
在所述第四搅拌中，通过以较高的搅拌自转速度快速搅拌，实现物料的充分混合与分散，使得浆料满足锂离子电池加工性能及电性能。
在任意实施方式中，所述正极浆料的固含量为63％～73％，且所述正极浆料的初始粘度为8000mPa·s～35000mPa·s。
本申请的制备方法成型的浆料固含量高，粘度适宜，具有优异的加工性，上述浆料可以直接用于后续的涂布工艺，能够提高生产效率。
在任意实施方式中，所述第二搅拌中使用的溶剂和所述第四搅拌中使用的溶剂相同，基于所述导电剂、所述正极活性材料、所述第一粘结剂、所述第二粘结剂的总质量计，所述第二搅拌中使用的溶剂的质量含量为35％～40％，所述第四搅拌中使用的溶剂的质量含量为5％～10％。
在任意实施方式中，所述正极浆料中，所述正极活性材料的质量、所述第一粘结剂和所述第二粘结剂的总质量、所述导电剂的质量比为(82～95):(3～10):(2～8)。
上述范围内的正极浆料既有良好的加工性能，又使得成型后的正极极片具有优异的电化学性能。
在任意实施方式中，所述正极活性材料为磷酸铁锂、钴酸锂、锰酸锂中的一种或几种。
在任意实施方式中，所述导电剂为导电炭黑、石墨、碳纳米管中的一种或几种。
本申请的第二方面还提供一种正极浆料，所述正极浆料是通过第一方面的正极浆料的制备方法制备的。
在任意实施方式中，所述正极浆料的粘度为8000mPa·s～35000mPa·s，且静置24小时后，所述正极浆料的粘度不超过48000mPa·s。
本申请提供的正极浆料具有适宜的粘度、优异的稳定性、以及良好的加工性。
本申请的第三方面还提供一种正极极片，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，所述正极膜层由第一方面所述的制备方法制备的正极浆料制备而得。该正极极片具有高的均匀性和粘结力。
在任意实施方式中，所述正极膜层与所述正极集流体间单位长度的粘结力大于20N/m。该正极极片的正极膜层与正极集流体之间具有高粘结强度，在使用过程中，正极膜层不容易从正极集流体上脱落，有助于提高电池的循环性能和安全性。
本申请的第四方面还提供一种二次电池，包括正极极片、隔离膜、负极极片以及电解液，所述正极极片由第一方面所述的制备方法制备的正极浆料或者第二方面所述的正极浆料制备而得。
在任意实施方式中，所述二次电池为锂离子电池、钠离子电池、镁离子电池、钾离子电池中的任意一种。
本申请的第五方面还提供一种电池模块，包括本申请第四方面所述的二次电池。
本申请的第六方面提供一种电池包，包括本申请第四方面所述的二次电池或者本申请的第五方面所述的电池模块。
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所述的二次电池、本申请的第五方面所述的电池模块或本申请的第六方面所述的电池包中的至少一种。
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粘结剂、制备方法、电极、电池及用电装置的实施方式。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)。
正极浆料主要是由正极活性材料、导电剂、粘结剂和溶剂形成的固-液相混合体系。为了提高体系中不同组分分布的均匀性，常通过搅拌、球磨、超声等工艺进行合浆。然而，现有技术中的合浆工艺通常只适用于固定组分的浆料体系，通用性差，浆料中各组分的物性发生变化后，合浆工艺往往需要调整。例如，现有技术中的合浆工艺不能适用于高分子量粘结剂，申请人经过大量研究发现高分子量粘结剂能够有效降低极片中的粘结剂用量，有助于提高极片的负载量，但是含有高分子量粘结剂的浆料往往出货粘度大，浆料极易凝胶，难以满足极片的生产需求。
[正极浆料]
基于此，本申请提出了一种正极浆料的制备方法，包括第一搅拌、第二搅拌、第三搅拌和第四搅拌；第一搅拌中，将正极活性材料、导电剂与第一粘结剂混合搅拌，制备干混料；第二搅拌中，将第二粘结剂与溶剂混合搅拌，制备胶液；第三搅拌中，将干混料与胶液混合搅拌，制备初级浆料；第四搅拌中，将溶剂与初级浆料混合搅拌，制备正极浆料；其中，第二粘结剂中聚合物的重均分子量小于第一粘结剂中任意聚合物的重均分子量。
在一些实施方式中，正极活性材料为磷酸铁锂、钴酸锂、锰酸锂中的一种或几种。
在一些实施方式中，导电剂包括导电炭黑、石墨、碳纳米管中 的一种或几种。
在一些实施方式中，溶剂为水性介质，如去离子水。在一些实施方式中，溶剂为油性介质，选自N-甲基-吡咯烷酮、N,N-二甲基丙酰胺、N,N-二乙基丙酰胺、N,N-二丙基丙酰胺、N,N-二丁基丙酰胺、N,N-二甲基乙基丙酰胺以及3-丁氧基-N-甲基丙酰胺中的一种或多种。
在该制备方法中，先将正极活性材料、导电剂和具有较高分子量的第一粘结剂进行第一搅拌得到干混料，第一搅拌使三者机械铆合，形成紧密缠结；然后将第二粘结剂与溶剂混合进行第二搅拌制备胶液，并且第二粘结剂中聚合物的重均分子量小于粘结剂中任意聚合物的重均分子量，较低粘度的胶液制备有利于后续含有大分子量聚合物的干混料在胶液中的分散；再将第一搅拌制备的干混料与胶液混合进行第三搅拌制备初级浆料，第三搅拌可以有效地将正极活性材料和导电剂分散于胶液中，胶液中的粘结剂可以通过静电作用和空间位阻作用提高浆料的稳定性，减少正极活性材料和导电剂的团聚以及沉降；最后将溶剂与初级浆料混合进行第四搅拌，得到正极浆料，第四搅拌中通过再次加入的溶剂能够有效调节浆料的出货粘度，防止出货粘度过高，影响后续的涂布工作。
本申请通过将低分子量的第二粘结剂与相对高分子量的第一粘结剂分步混合，降低了正极浆料的出货粘度，提高了正极浆料的可加工性，且该方法具有广泛的通用性，能够适用于包含新一代高分子量聚合物粘结剂的浆料制备。
在一些实施方式中，第二粘结剂为重均分子量不超过400万的聚偏氟乙烯。
控制第二粘结剂为重均分子量不超过400万的聚偏氟乙烯，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能、以及提升正极极片的粘结性能。
在一些实施方式中，第二粘结剂中聚偏氟乙烯的重均分子量可选为10万、20万、30万、40万、50万、60万、70万、80万、90万、100万、110万、120万、130万、140万、150万、160万、170 万、180万、190万、200万、250万、300万、350万、400万中的任意一种。
在本文中，术语“重均分子量”是指聚合物按质量的统计平均分子量，在单位重量上平均得到的分子量。在本申请中，聚合物的重均分子量的测试可以选用本领域已知的方法进行测试，作为示例，采用凝胶色谱法进行测试，如采用Waters 2695 Isocratic HPLC型凝胶色谱仪(示差折光检测器2141)。以质量分数为3.0％的聚苯乙烯溶液试样做参比，选择匹配的色谱柱(油性：Styragel HT5DMF7.8×300mm+Styragel HT4)。用纯化后的N-甲基吡咯烷酮(NMP)溶剂配置3.0％的聚合物溶液，配置好的溶液静置一天，备用。测试时，先用注射器吸取四氢呋喃，进行冲洗，重复几次。然后吸取5ml实验溶液，排除注射器中的空气，将针尖擦干。最后将试样溶液缓缓注入进样口。待示数稳定后获取数据，读取重均分子量。
在一些实施方式中，第二粘结剂为重均分子量不超过200万的聚偏氟乙烯。
控制第二粘结剂为重均分子量不超过200万的聚偏氟乙烯，可以进一步降低正极浆料的出货粘度和静置24小时后的粘度，更大程度上减缓正极浆料凝胶和改善正极浆料的过滤性能。
在一些实施方式中，第二粘结剂为重均分子量不超过150万的聚偏氟乙烯。
控制第二粘结剂为重均分子量不超过150万的聚偏氟乙烯，可以再进一步降低正极浆料的出货粘度和静置24小时后的粘度，大幅减缓正极浆料的凝胶和改善正极浆料的过滤性能。
在一些实施方式中，第一粘结剂中包含一种或多种重均分子量的聚偏氟乙烯，且第一粘结剂中包含重均分子量不小于200万的聚偏氟乙烯。在一些实施方式中，第一粘结剂中包含一种重均分子量的聚偏氟乙烯，且其重均分子量不小于200万。在一些实施方式中，第一粘结剂中包含两种或更多种不同重均分子量的聚偏氟乙烯，且其中至少一种聚偏氟乙烯的重均分子量不小于200万。在一些实施 方式中，第一粘结剂中包含重均分子量不小于400万的聚偏氟乙烯。
重均分子量不小于200万的聚偏氟乙烯的重均分子量可选为200万、250万、300万、350万、400万、450万、500万、550万、600万、650万、700万、750万、800万、850万、900万中的任意一种或几种。
现有技术中的正极浆料的制备方法兼容性差，不能满足不同分子量粘结剂的制备需求，也无法对新一代高分子量聚合物粘结剂进行高质量合浆。本申请公开的制备方法具有通用性，适用于不同重均分子量的粘结剂，尤其能够满足新一代高分子量聚合物粘结剂的制备需求，有效降低正极浆料的出货粘度和静置24小时后的粘度，有助于提高正极浆料的涂布性和加工性。
在一些实施方式中，第二粘结剂的质量含量为30％～50％，基于第一粘结剂和第二粘结剂的总质量计。在一些实施方式中，第二粘结剂的质量含量可选为30％、32％、34％、35％、36％、38％、40％、42％、44％、45％、46％、48％、50％中的任意一种。
基于第一粘结剂和第二粘结剂的总质量计，控制第二粘结剂的质量含量为30％～50％，既能充分发挥第一粘结剂中高分子量聚合物粘结性能强的作用，提升正极极片的粘结性能，又能保证正极浆料的加工性能，确保其具有较低的出货粘度、静置24小时后的粘度、以及优异的抗凝胶性能和过滤性。
在一些实施方式中，第一搅拌的自转速度为0。在一些实施方式中，第一搅拌的公转速度为10转/分钟～20转/分钟。在一些实施方式中，第一搅拌的公转速度可选为10转/分钟、11转/分钟、12转/分钟、13转/分钟、14转/分钟、15转/分钟、16转/分钟、17转/分钟、18转/分钟、19转/分钟、20转/分钟中的任意一种。
在本文中，术语“自转速度”是指搅拌器绕自身轴线转动的速度。
在本文中，术语“公转速度”是指搅拌器绕装载物料的釜体转动的速度。
在一些实施方式中，搅拌装置为行星搅拌机。行星搅拌机的工作原理是搅拌机启动后，行星架转动，带动箱内搅拌轴转动，在围绕料筒轴线公转的同时高速自转，从而物料受到强烈的剪切、捏合作用。可以理解，本申请提供的制备方法适用于任何类型的行星搅拌机。
控制第一搅拌的自转速度为0，可以减少干混过程中对物料的损伤。控制第一搅拌的公转速度为10转/分钟～20转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度，改善正极浆料的过滤性能，提升正极极片的粘结性能，同时也有利于降低生产成本。
在一些实施方式中，第一搅拌的搅拌时间为10分钟～25分钟。在一些实施方式中，第一搅拌的搅拌时间可选为10分钟、12分钟、14分钟、15分钟、16分钟、18分钟、20分钟、22分钟、24分钟、25分钟中的任意一种。
控制第一搅拌的搅拌时间为10分钟～25分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于提高生产效率，降低生产成本。
在一些实施方式中，第二搅拌的公转速度为20转/分钟～30转/分钟。在一些实施方式中，第二搅拌的公转速度可选为20转/分钟、21转/分钟、22转/分钟、23转/分钟、24转/分钟、25转/分钟、26转/分钟、27转/分钟、28转/分钟、29转/分钟、30转/分钟中的任意一种。
控制第二搅拌的公转速度为20转/分钟～30转/分钟，可以有效降低正极浆料的出货粘度、静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于降低生产成本。
在一些实施方式中，第二搅拌的自转速度为1000转/分钟～1400转/分钟。在一些实施方式中，第二搅拌的自转速度可选为1000转/分钟、1050转/分钟、1100转/分钟、1150转/分钟、1200转/分钟、 1250转/分钟、1300转/分钟、1350转/分钟、1400转/分钟中的任意一种。
控制第二搅拌的自转速度为1000转/分钟～1400转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于降低生产成本。
在一些实施方式中，第二搅拌的搅拌时间为60分钟～90分钟。在一些实施方式中，第二搅拌的搅拌时间可选为60分钟、62分钟、65分钟、68分钟、70分钟、73分钟、75分钟、77分钟、80分钟、85分钟、90分钟中的任意一种。
控制第二搅拌的搅拌时间为60分钟～90分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能，同时也有利于提高生产效率，降低生产成本。
在一些实施方式中，第三搅拌的搅拌时间为60分钟～90分钟，公转速度为20转/分钟～30转/分钟，自转速度为500转/分钟～800转/分钟。
在一些实施方式中，第三搅拌的搅拌时间可选为60分钟、70分钟、80分钟、90分钟中的任意一种。在一些实施方式中，公转速度可选为20转/分钟、25转/分钟、30转/分钟的任意一种。在一些实施方式中，自转速度可选为500转/分钟、550转/分钟、600转/分钟、650转/分钟、700转/分钟、750转/分钟、800转/分钟的任意一种。
在第三搅拌中通过将第一搅拌中制备的干混料加入第二搅拌中制备的胶液中慢搅，降低第一粘结剂中高分子量聚合物团聚凝胶的风险，提高物料间捏合的均匀性。
在一些实施方式中，第四搅拌的公转速度为20转/分钟～30转/分钟，自转速度为1000转/分钟～1400转/分钟，搅拌时间为90分钟～120分钟。
在一些实施方式中，第四搅拌的公转速度可选为20转/分钟、25转/分钟或30转/分钟。在一些实施方式中，自转速度可选为1000转/分钟、1100转/分钟、1200转/分钟、1300转/分钟或1400转/分钟。在一些实施方式中，搅拌时间可选为90分钟、100分钟、110分钟或120分钟。
在一些实施方式中，在第四搅拌中，通过以较高的搅拌自转速度快速搅拌，实现物料的充分混合与分散，使得浆料满足锂离子电池加工性能及电性能。
在任意实施方式中，所述正极浆料的固含量为63％～73％，且所述正极浆料的初始粘度为8000mPa·s～35000mPa·s。
在一些实施方式中，正极浆料的固含量为63％～73％，且正极浆料的初始粘度为8000mPa·s～35000mPa·s。在一些实施方式中，正极浆料的初始粘度可选为8000mPa.s、9000mPa.s、10000mPa.s、11000mPa.s、12000mPa.s、13000mPa.s、14000mPa.s、15000mPa.s、16000mPa.s、17000mPa.s、18000mPa.s、19000mPa.s、20000mPa.s、22000mPa.s、23000mPa.s、24000mPa.s、25000mPa.s、26000mPa.s、27000mPa.s、28000mPa.s、29000mPa.s、30000mPa.s、30500mPa.s、31000mPa.s、32000mPa.s、33000mPa.s、34000mPa.s、35000mPa·s中的任意一种。
正极浆料的初始粘度即指正极浆料的出货粘度，将正极浆料制备完成出货时的粘度记为正极浆料的初始粘度。
在本申请中，正极浆料的粘度的测试可以选用本领域已知的方法进行测试，例如采用旋转粘度剂测量浆料的粘度。选取合适的转子，固定好粘度计转子，将浆料放置于粘度计转子下方，浆料恰好淹没转子的刻度线，仪器型号：上海方瑞NDJ-5S，转子：63#(2000-10000mPa.s)、64#(10000-50000mPa.s)，转速：12转/分钟，测试温度：25℃，测试时间为5分钟，待示数稳定读取数据。
固含量为63％～73％的正极浆料的初始粘度为8000mPa·s～35000mPa·s，该正极浆料具有良好的涂布性和加工性，扩宽了涂布工艺窗口。
在一些实施方式中，第二搅拌中使用的溶剂和第四搅拌中使用的溶剂相同，基于导电剂、正极活性材料、第一粘结剂、第二粘结剂的总质量计，第二搅拌中使用的溶剂的质量含量为35％～40％，第四搅拌中使用的溶剂的质量含量为5％～10％。
在一些实施方式中，第二搅拌中使用的溶剂的质量含量可选自35％、36％、37％、38％、39％或40％，第四搅拌中使用的溶剂的质量含量可选自5％、6％、7％、8％、9％或10％，基于导电剂、正极活性材料、第一粘结剂、第二粘结剂的总质量计。
在一些实施方式中，正极浆料中，正极活性材料、第一粘结剂和第二粘结剂的总质量、导电剂的质量比为(82～95):(3～10):(2～8)。在一些实施方式中，正极浆料中，正极活性材料、第一粘结剂和第二粘结剂的总质量、导电剂的质量比可选为95:3:2、94:4:2、93:5:2、92:5:3、91:6:3、90:8:2、90:5:5、90:7:2、88:8:4、88:5:7、82:10:8中的任意一种。
上述范围内的正极浆料既有良好的加工性能，又使得成型后的正极极片具有优异的电化学性能。
在一些实施方式中，正极活性材料为磷酸铁锂、钴酸锂、锰酸锂中的一种或几种。
上述正极活性材料，使得电池具有高的能量密度，有利于提高电池的循环性能。
在一些实施方式中，导电剂为导电炭黑、石墨、碳纳米管中的一种或几种。
上述导电剂有利于提高电池的电导率。
本申请提供一种正极浆料，该正极浆料由本申请任意实施方式中的制备方法制备而得。
在一些实施方式中，正极浆料的固含量为63％～73％，且正极浆料的初始粘度为8000mPa·s～35000mPa·s，且静置24小时后，正极浆料的粘度不超过48000mPa·s。在一些实施方式中，正极浆料的初始粘度可选为8000mPa.s、9000mPa.s、10000mPa.s、11000mPa.s、12000mPa.s、13000mPa.s、14000mPa.s、15000mPa.s、16000mPa.s、 17000mPa.s、18000mPa.s、19000mPa.s、20000mPa.s、22000mPa.s、23000mPa.s、24000mPa.s、25000mPa.s、26000mPa.s、27000mPa.s、28000mPa.s、29000mPa.s、30000mPa.s、30500mPa.s、31000mPa.s、32000mPa.s、33000mPa.s、34000mPa.s、35000mPa·s中的任意一种。在一些实施方式中，静置24小时后，正极浆料的粘度可选为8000mPa.s、9000mPa.s、10000mPa.s、11000mPa.s、12000mPa.s、13000mPa.s、14000mPa.s、15000mPa.s、16000mPa.s、17000mPa.s、18000mPa.s、19000mPa.s、20000mPa.s、22000mPa.s、23000mPa.s、24000mPa.s、25000mPa.s、26000mPa.s、27000mPa.s、28000mPa.s、29000mPa.s、30000mPa.s、30500mPa.s、31000mPa.s、32000mPa.s、33000mPa.s、34000mPa.s、36000mPa.s、38000mPa.s、40000mPa.s、42000mPa.s、44000mPa.s、48000mPa.s中的任意一种。
该正极浆料具有适宜的粘度、优异的稳定性、以及良好的加工性。
[正极极片]
本申请提供一种正极极片，其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，正极膜层由本申请任意实施方式中的制备方法制备而得。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，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，正极膜层与正极集流体间单位长度的粘结力大于20N/m。在一些实施方式中，正极膜层与正极集流体间单位长度的粘结力为20N/m～30N/m，可选为。在一些实施方式中，正极膜层与正极集流体间单位长度的粘结力可选为20N/m、20.5N/m、21N/m、21.5N/m、22N/m、22.5N/m、23N/m、23.5N/m、24N/m、24.5N/m、25N/m、27N/m、30N/m中的任意一种。
在本文中，粘结力主要用于表征正极极片中正极浆料制备的膜层与集流体之间的粘结强度，其可以通过任意公知方法进行测试。作为示例，正极膜层与正极集流体间单位长度的粘结力的测试可以选用本领域已知的方法进行测试，例如参考GB-T2790-1995国标《胶粘剂180°剥离强度实验方法》，本申请实施例和对比例的粘结力测试过程如下：用刀片截取宽度为30mm，长度为100-160mm的试样，将专用双面胶贴于钢板上，胶带宽度20mm，长度90-150mm。将前面截取的极片试样的涂层面贴在双面胶上，后用2kg压辊沿同一个方向滚压三次。将宽度与极片等宽，长度为250mm 的纸带固定于极片集流体上，并且用皱纹胶固定。打开三思拉力机电源(灵敏度为1N)，指示灯亮，调整限位块到合适位置，将钢板未贴极片的一端用下夹具固定。将纸带向上翻折，用上夹具固定，利用拉力机附带的手动控制器上的“上行”和“下行”按钮调整上夹具的位置。然后进行测试并读取数值，拉伸速度为50mm/min。将极片受力平衡时的力除以胶带的宽度作为单位长度的极片的粘结力，以表征正极膜层与集流体之间的粘结强度。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，负极膜层包括负极活性材料。
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。
在一些实施方式中，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，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。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负极活性材料的传统材料。这些负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。
在一些实施方式中，负极膜层还可选地包括粘结剂。粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基 丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、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，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将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。
[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，电解质采用电解液。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，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。
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能够盖设于开口，以封闭容纳腔。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，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。二次电池、电池模块、或电池包可以用作用电装置的电源，也可以用作用电装置的能量存储单元。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。
一、制备方法
实施例1
1)正极浆料的制备
称取原料：按照正极浆料配比称取原料，正极活性材料∶第一粘结剂∶第二粘结剂：导电剂的质量比为95:1.5:1.5:2，其中正极活性材料的质量为1200kg，正极活性材料为磷酸铁锂，第一粘结剂为重均分子量为200万的聚偏氟乙烯，第二粘结剂为重均分子量为100万的聚偏氟乙烯，导电剂为导电炭黑；
第一搅拌：将磷酸铁锂、导电炭黑和第一粘结剂混合，充分搅拌，公转速度为15转/分钟，自转速度为0，搅拌时间为15分钟，得到干混料；
第二搅拌：将第二粘结剂与N-甲基吡咯烷酮(NMP)溶剂混合，充分搅拌，第二搅拌中加入的NMP溶剂的质量为正极活性材料、第一粘结剂、第二粘结剂和导电剂的总质量的35％，公转速度为25转/分钟，自转速度为1200转/分钟，搅拌时间为60分钟，得到胶液；
第三搅拌：将上述干混料加入到上述胶液，充分搅拌，公转速度为25转/分钟，自转速度为600转/分钟，搅拌时间为60分钟，得到初级浆料；
第四搅拌：将NMP溶剂加入到上述初级浆料，其中，第四搅拌中加入的NMP溶剂的质量为正极活性材料、第一粘结剂、第二粘结剂和导电剂的总质量的10％，公转速度为25转/分钟，自转速度为1200转/分钟，搅拌时间为110分钟，得到固含量为68％±5％的正极浆料。
2)极片的制备
将实施例1制备的正极浆料均匀涂覆于正极集流体铝箔上，之 后经过烘干、冷压、分切，得到正极极片。
实施例2～3
制备方法与实施例1基本相同，区别在于将第一搅拌中第一粘结剂分别调整为重均分子量为400万的聚偏氟乙烯、重均分子量为800万的聚偏氟乙烯，具体参数参见表格1。
实施例4～8
制备方法与实施例3基本相同，区别在于将第二搅拌中第二粘结剂分别调整为重均分子量为400万的聚偏氟乙烯、重均分子量为300万的聚偏氟乙烯、重均分子量为200万的聚偏氟乙烯、重均分子量为150万的聚偏氟乙烯、重均分子量为50万的聚偏氟乙烯，具体参数参见表格1。
实施例9～12
制备方法与实施例3基本相同，区别在于调整第一粘结剂和第二粘结剂的质量比，具体参数参见表格1。
实施例13～16
制备方法与实施例1基本相同，区别在于调整第一粘结剂为组合物，以实施例13为例，第一粘结剂为重均分子量200万的聚偏氟乙烯和重均分子量400万的聚偏氟乙烯的组合物，其中第一粘结剂中重均分子量200万的聚偏氟乙烯占粘结剂总量的30％，重均分子量400万的聚偏氟乙烯占粘结剂总量的40％，第二粘结剂中重均分子量100万的聚偏氟乙烯占粘结剂总量的30％。其他实施例中具体参数参见表格1。
实施例17～44
制备方法与实施例3基本相同，区别在于调整了第一搅拌和第二搅拌的搅拌参数，具体参数参见表1。
对比例1
称取原料：按照正极浆料配比称取原料，正极活性材料∶粘结剂∶导电剂的质量比为95:3:2，其中正极活性材料的质量为1200kg，正极活性材料为磷酸铁锂，粘结剂为重均分子量为200万的聚偏氟乙烯，导电剂为导电炭黑；
第一搅拌：将磷酸铁锂和导电炭黑混合，充分搅拌，公转速度为15转/分钟，自转速度为0，搅拌时间为15分钟，得到干混料；
第二搅拌：将粘结剂与NMP溶剂混合，充分搅拌，加入的溶剂的质量为正极活性材料、粘结剂和导电剂的总质量的35％，公转速度为25转/分钟，自转速度为1200转/分钟，搅拌时间为60分钟，得到胶液；
第三搅拌：将第一搅拌制备的干混料加入到第二搅拌制备的胶液，充分搅拌，公转速度为25转/分钟，自转速度为600转/分钟，搅拌时间为60分钟，得到初级浆料；
第四搅拌：将NMP溶剂加入到初级浆料，加入的溶剂的质量为正极活性材料、粘结剂和导电剂的总质量的10％，公转速度为25转/分钟，自转速度为1200转/分钟，搅拌时间为110分钟，得到固含量为68％±5％的正极浆料。
对比例2～8
与对比例1基本相同，区别在于调制了粘结剂的重均分子量，具体的参数参见表1。
二、测试方法
1、重均分子量
采用Waters 2695 Isocratic HPLC型凝胶色谱仪(示差折光检测器2141)。以质量分数为3.0％的聚苯乙烯溶液试样做参比，选择匹配的色谱柱(油性：Styragel HT5DMF7.8×300mm+Styragel HT4)。用纯化后的N-甲基吡咯烷酮(NMP)溶剂配置3.0％的聚合物溶液，配置好的溶液静置一天，备用。测试时，先用注射器吸取四氢呋喃，进行冲洗，重复几次。然后吸取5ml实验溶液，排除注射器中的空气，将针尖擦干。最后将试样溶液缓缓注入进样口。待示数稳定后获取数据，读取重均分子量。
2、浆料粘度测试
使用旋转粘度剂测量浆料的粘度。选取合适的转子，固定好粘度计转子，将浆料放置于粘度计转子下方，浆料恰好淹没转子的刻度线，仪器型号：上海方瑞NDJ-5S，转子：63#(2000-10000mPa.s)、 64#(10000-50000mPa.s)，转速：12转/分钟，测试温度：25℃，测试时间为5分钟，待示数稳定读取数据。
3、浆料静置24小时之后的粘度测试
将静置24小时后的浆料重新进行粘度测试，使用旋转粘度剂测量浆料的粘度。选取合适的转子，固定好粘度计转子，将浆料放置于粘度计转子下方，浆料恰好淹没转子的刻度线，仪器型号：上海方瑞NDJ-5S，转子：63#(2000-10000mPa.s)、64#(10000-50000mPa.s)，转速：12转/分钟，测试温度：25℃，测试时间为5分钟，待示数稳定读取数据。
4、浆料静置24小时之后的凝胶状态测试
浆料静置24小时后，使用钢直尺挑起烧杯中的浆料，根据浆料流动状态判断浆料的凝胶状态。
无凝胶状态为浆料自然流动不断流，浆料在钢尺表面平流，无结块；
轻微凝胶状态为浆料自然流动不断流，但流体较细，浆料在钢尺表面基本平摊，有轻微小块；
中度凝胶状态为浆料自然滴落、时断时续；不连续成流，浆料在钢尺表面无法平摊，有明显块状团聚；
严重凝胶状态为浆料无法成流流下，结成块掉落或直接留在钢尺上无法流下。
5、过滤性能测试
取500ml烧杯置于200目滤网支架下端，取导电浆料500ml，置于滤网中过滤，记录烧杯中浆料体积到达300ml时的时间，记录时间。
6、极片的粘结力测试
参考GB-T2790-1995国标《胶粘剂180°剥离强度实验方法》，本申请实施例和对比例的粘结力测试过程如下：用刀片截取宽度为30mm，长度为100-160mm的试样，将专用双面胶贴于钢板上，胶带宽度20mm，长度90-150mm。将前面截取的极片试样的涂层面贴在双面胶上，后用2kg压辊沿同一个方向滚压三次。将宽度与极 片等宽，长度为250mm的纸带固定于极片集流体上，并且用皱纹胶固定。打开三思拉力机电源(灵敏度为1N)，指示灯亮，调整限位块到合适位置，将钢板未贴极片的一端用下夹具固定。将纸带向上翻折，用上夹具固定，利用拉力机附带的手动控制器上的“上行”和“下行”按钮调整上夹具的位置。然后进行测试并读取数值，拉伸速度为50mm/min。将极片受力平衡时的力除以胶带的宽度作为单位长度的极片的粘结力，以表征正极膜层与集流体之间的粘结强度。
三、各实施例、对比例测试结果分析
按照上述方法分别制备各实施例和对比例，并测量各项性能参数，结果见下表1和表2。
表1实施例和对比例制备参数
Figure PCTCN2022131511-appb-000001
Figure PCTCN2022131511-appb-000002
Figure PCTCN2022131511-appb-000003
表2实施例和对比例性能参数测试结果
Figure PCTCN2022131511-appb-000004
Figure PCTCN2022131511-appb-000005
根据上述结果可知，实施例1～44中的正极浆料，均是采用本申请公开的浆料制备方法制备的，均包括第一搅拌、第二搅拌、第三搅拌和第四搅拌；第一搅拌中，将正极活性材料磷酸铁锂、导电剂导电炭黑和第一粘结剂聚偏氟乙烯混合搅拌，制备干混料；第二搅拌中，将第二粘结剂聚偏氟乙烯与NMP溶剂混合搅拌，制备胶液； 第三搅拌中，将干混料与胶液混合搅拌，制备初级浆料；第四搅拌中，将NMP溶剂与初级浆料混合搅拌，制备正极浆料；其中，第二粘结剂中聚偏氟乙烯的重均分子量小于第一粘结剂中任意聚偏氟乙烯的重均分子量。从实施例1～44与对比例1～8的对比可见，本申请提供的正极浆料的制备方法能够有效降低正极浆料的粘度，提高浆料的可加工性。该制备方法不但适用于现有技术中的聚合物，尤其适用于大分子量聚合物，具有广泛的通用性。
从实施例3～8与对比例6的对比可见，控制第二粘结剂为重均分子量不超过400万的聚偏氟乙烯，可以有效的降低正极浆料的出货粘度和静置24小时后的粘度，减缓正极浆料凝胶、改善正极浆料的过滤性能、以及提升正极极片的粘结性能。从实施例3、6～8与实施例6的对比可见，控制第二粘结剂为重均分子量不超过200万的聚偏氟乙烯，可以进一步降低正极浆料的出货粘度和静置24小时后的粘度，更大程度上减缓正极浆料凝胶和改善正极浆料的过滤性能。从实施例3、7～8与实施例6的对比可见，控制第二粘结剂为重均分子量不超过150万的聚偏氟乙烯，可以再进一步降低正极浆料的出货粘度和静置24小时后的粘度，大幅减缓正极浆料的凝胶和改善正极浆料的过滤性能。
从实施例1～16与对比例1～8的对比可见，该制备方法对于第一粘结剂中包含一种或多种重均分子量的聚偏氟乙烯均适用，尤其适用于包含重均分子量不小于200万的聚偏氟乙烯的第一粘结剂。
从实施例3、实施例10～11与实施例9、实施例12的对比可见，基于第一粘结剂和第二粘结剂的总质量计，控制第二粘结剂的质量含量为30％～50％，既能充分发挥第一粘结剂中高分子量聚合物粘结性能强的作用，提升正极极片的粘结性能，又能保证正极浆料的加工性能，确保其具有较低的出货粘度、静置24小时后的粘度、以及优异的抗凝胶性能和过滤性。
从实施例3、实施例18～19与实施例17的对比可见，控制第一搅拌的公转速度为10转/分钟～20转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、，改善正极浆料的过滤性能 和提升正极极片的粘结性能；从实施例3、实施例18～19与实施例20的对比可见，控制第一搅拌的公转速度为10转/分钟～20转/分钟，在保证正极浆料的粘结性能和过滤性能、以及正极极片的粘结性能的前提下可以降低生产成本。
从实施例3、实施例22～23与实施例21的对比可见，控制第一搅拌的搅拌时间为10分钟～25分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例22～23与实施例24的对比可见，控制第一搅拌的搅拌时间为10分钟～25分钟，在保证正极浆料的粘结性能和过滤性能、以及正极极片的粘结性能的前提下可以提高生产效率和生产成本。
从实施例3、实施例26～27与实施例25的对比可见，控制第二搅拌的公转速度为20转/分钟～30转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例26～27与实施例28的对比可见，控制第二搅拌的公转速度为20转/分钟～30转/分钟，在保证正极浆料的粘结性能和过滤性能、以及正极极片的粘结性能的前提下可以降低生产成本。
从实施例3、实施例30～31与实施例29的对比可见，控制第二搅拌的自转速度为1000转/分钟～1400转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例30～31与实施例32的对比可见，控制第二搅拌的自转速度为1000转/分钟～1400转/分钟，在保证正极浆料的粘结性能和过滤性能、以及正极极片的粘结性能的前提下可以减缓正极浆料和降低生产成本。
从实施例3、实施例34～35与实施例33的对比可见，控制第二搅拌的搅拌时间为60分钟～90分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例34～35 与实施例36的对比可见，控制第二搅拌的搅拌时间为60分钟～90分钟，在保证正极浆料的粘结性能和过滤性能、以及正极极片的粘结性能的前提下可以提高生产效率和降低生产成本。
从实施例3、实施例38～39与实施例37的对比可见，控制第三搅拌的自转速度为500转/分钟～800转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例38～39与实施例40的对比可见，控制第三搅拌的自转速度为500转/分钟～800转/分钟，在保证正极浆料的粘结性能、过滤性能以及正极极片的粘结性能的同时还能够降低成本。
从实施例3、实施例42～43与实施例41的对比可见，控制第四搅拌的自转速度为1000转/分钟～1400转/分钟，可以有效的降低正极浆料的出货粘度、静置24小时后的粘度、减缓正极浆料凝胶、改善正极浆料的过滤性能和提升正极极片的粘结性能；从实施例3、实施例42～43与实施例44的对比可见，控制第四搅拌的自转速度为1000转/分钟～1400转/分钟，在能够保证正极浆料的粘结性能、过滤性能以及正极极片的粘结性能的同时能够降低生产成本。
从实施例可见，本申请公开的正极浆料的固含量为63％～73％，且正极浆料的粘度为8000mPa·s～35000mPa·s，该正极浆料具有良好的涂布性和可加工性。
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 (27)

  1. 一种正极浆料的制备方法，其特征在于，包括第一搅拌、第二搅拌、第三搅拌和第四搅拌；
    所述第一搅拌中，将正极活性材料、导电剂与第一粘结剂混合搅拌，制备干混料；
    所述第二搅拌中，将第二粘结剂与溶剂混合搅拌，制备胶液；
    所述第三搅拌中，将所述干混料与所述胶液混合搅拌，制备初级浆料；
    所述第四搅拌中，将溶剂与所述初级浆料混合搅拌，制备正极浆料；
    其中，所述第二粘结剂中聚合物的重均分子量小于所述第一粘结剂中任意聚合物的重均分子量。
  2. 根据权利要求1所述的制备方法，其特征在于，所述第二粘结剂为重均分子量不超过400万的聚偏氟乙烯。
  3. 根据权利要求1或2所述的制备方法，其特征在于，所述第二粘结剂为重均分子量不超过200万的聚偏氟乙烯。
  4. 根据权利要求1至3中任一项所述的制备方法，其特征在于，所述第一粘结剂中包含一种或多种重均分子量的聚偏氟乙烯，且所述第一粘结剂中包含重均分子量不小于200万的聚偏氟乙烯。
  5. 根据权利要求1至4中任一项所述的制备方法，其特征在于，所述第一粘结剂中包含重均分子量不小于400万的聚偏氟乙烯。
  6. 根据权利要求1至5中任一项所述的制备方法，其特征在于，所述第二粘结剂的质量含量为30％～50％，基于所述第一粘结 剂和所述第二粘结剂的总质量计。
  7. 根据权利要求1至6中任一项所述的制备方法，其特征在于，所述第一搅拌的自转速度为0，公转速度为10转/分钟～20转/分钟。
  8. 根据权利要求1至7中任一项所述的制备方法，其特征在于，所述第一搅拌的搅拌时间为10分钟～25分钟。
  9. 根据权利要求1至8中任一项所述的制备方法，其特征在于，所述第二搅拌的公转速度为20转/分钟～30转/分钟。
  10. 根据权利要求1至9中任一项所述的制备方法，其特征在于，所述第二搅拌的自转速度为1000转/分钟～1400转/分钟。
  11. 根据权利要求1至10中任一项所述的制备方法，其特征在于，所述第二搅拌的搅拌时间为60分钟～90分钟。
  12. 根据权利要求1至11中任一项所述的制备方法，其特征在于，所述第三搅拌的搅拌时间为60分钟～90分钟，公转速度为20转/分钟～30转/分钟，自转速度为500转/分钟～800转/分钟。
  13. 根据权利要求1至12中任一项所述的制备方法，其特征在于，所述第四搅拌的公转速度为20转/分钟～30转/分钟，自转速度为1000转/分钟～1400转/分钟，搅拌时间为90分钟～120分钟。
  14. 根据权利要求1至13中任一项所述的制备方法，其特征在于，所述正极浆料的固含量为63％～73％，且所述正极浆料的初始粘度为8000mPa·s～35000mPa·s。
  15. 根据权利要求1至14中任一项所述的制备方法，其特征在于，所述第二搅拌中使用的溶剂和所述第四搅拌中使用的溶剂相同，基于所述导电剂、所述正极活性材料、所述第一粘结剂、所述第二粘结剂的总质量计，所述第二搅拌中使用的溶剂的质量含量为35％～40％，所述第四搅拌中使用的溶剂的质量含量为5％～10％。
  16. 根据权利要求1至15中任一项所述的制备方法，其特征在于，所述正极浆料中，所述正极活性材料的质量、所述第一粘结剂和所述第二粘结剂的总质量、所述导电剂的质量比为(82～95):(3～10):(2～8)。
  17. 根据权利要求1至16中任一项的制备方法，所述正极活性材料为磷酸铁锂、钴酸锂、锰酸锂中的一种或几种。
  18. 根据权利要求1至17中任一项所述的制备方法，所述导电剂为导电炭黑、石墨、碳纳米管中的一种或几种。
  19. 一种正极浆料，其特征在于，其是通过权利要求1至18中任一项所述的制备方法制备的。
  20. 根据权利要求19所述的正极浆料，其特征在于，所述正极浆料的固含量为63％～73％，且所述正极浆料的初始粘度为8000mPa·s～35000mPa·s，且静置24小时后，所述正极浆料的粘度不超过48000mPa·s。
  21. 一种正极极片，其特征在于，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，所述正极膜层由权利要求1至18中任一项所述的制备方法制备的正极浆料制备而得。
  22. 根据权利要求21所述的正极极片，其特征在于，所述正极膜层与所述正极集流体间单位长度的粘结力为大于20N/m。
  23. 一种二次电池，其特征在于，其特征在于，包括正极极片、隔离膜、负极极片以及电解液，所述正极极片由权利要求1至18中任一项所述的制备方法制备的正极浆料或权利要求19至20中任一项所述的正极浆料制备而得。
  24. 根据权利要求23所述的二次电池，其特征在于，所述二次电池为锂离子电池、钠离子电池、镁离子电池、钾离子电池中的任意一种。
  25. 一种电池模块，其特征在于，包括权利要求23或24所述的二次电池。
  26. 一种电池包，其特征在于，包括权利要求23或24所述的二次电池或权利要求25所述的电池模块。
  27. 一种用电装置，其特征在于，包括选自权利要求23或24所述的二次电池、权利要求25所述的电池模块、权利要求26所述的电池包中的至少一种。
PCT/CN2022/131511 2022-11-11 2022-11-11 正极浆料的制备方法、正极极片、二次电池、电池模块、电池包和用电装置 WO2024098411A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008243643A (ja) * 2007-03-28 2008-10-09 Hitachi Vehicle Energy Ltd リチウム二次電池
CN103887514A (zh) * 2014-04-15 2014-06-25 中国科学院宁波材料技术与工程研究所 一种锂离子电池正极浆料的制备方法
CN113659145A (zh) * 2021-08-10 2021-11-16 东莞维科电池有限公司 一种正极浆料及其制备方法、锂离子电池及其制备方法
CN115133035A (zh) * 2022-08-30 2022-09-30 宁德时代新能源科技股份有限公司 正极浆料及其制备方法、二次电池、电池模块、电池包和用电装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008243643A (ja) * 2007-03-28 2008-10-09 Hitachi Vehicle Energy Ltd リチウム二次電池
CN103887514A (zh) * 2014-04-15 2014-06-25 中国科学院宁波材料技术与工程研究所 一种锂离子电池正极浆料的制备方法
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CN115133035A (zh) * 2022-08-30 2022-09-30 宁德时代新能源科技股份有限公司 正极浆料及其制备方法、二次电池、电池模块、电池包和用电装置

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