Methods for preparing polymers, polymers and their uses, separators, batteries, electrical devices

Abstract

The present invention provides a method for preparing a polymer, the polymer and its use, a separator, a battery, and an electrical device. The method for preparing the polymer includes the steps of: mixing a polymer monomer, an initiator, and an emulsifier to obtain a mixture, wherein the polymer monomer comprises an acrylate monomer, the initiator comprises at least one of a persulfate initiator, an acyl peroxide initiator, and an azo initiator, and the emulsifier comprises an anionic emulsifier; polymerizing the mixture to obtain a polymer emulsion, wherein the viscosity of the polymer emulsion at 25°C is 100 mPa·s to 2000 mPa·s, and the solids content of the polymer emulsion is 20% to 60%; and granulating the polymer emulsion to obtain a polymer.

Description

[Technical Field]

[0001] This disclosure relates to the technology of batteries, and more specifically to methods for preparing polymers, polymers, separators, batteries, and electrical devices. [Background technology]

[0002] In recent years, batteries have been widely applied in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Binding agents act as inert materials in batteries, binding each component in the battery slurry together and adjacent battery components together. While the amount and cost of binding agents in batteries are very small, they can effectively improve battery performance. Binding agents must not only meet binding performance requirements but also withstand swelling and corrosion from the electrolyte, as well as electrochemical corrosion during the charge-discharge process. Therefore, there are few types of polymers that can be used as battery binding agents, and those that do meet the requirements often have complicated preparation processes, low yields, and limited application scenarios. Current polymers and their preparation methods still need further improvement.

[0003] It should be noted that the above explanation does not necessarily constitute prior art, and is merely intended to provide background art information related to this application. [Overview of the project]

[0004] In a first aspect of this application, the application proposes a method for preparing a polymer, comprising the steps of: mixing a polymer monomer, an initiator, and an emulsifier to obtain a mixture, wherein the polymer monomer comprises an acrylate monomer, the initiator comprises at least one of a persulfate initiator, an acyl peroxide initiator, and an azo initiator, and the emulsifier comprises an anionic emulsifier; polymerizing the mixture to obtain a polymer emulsion, wherein the polymer emulsion has a viscosity of 100 mPa·s to 2000 mPa·s at 25°C and a solids content of 20% to 60%; and granulating the polymer emulsion to obtain a polymer. This method allows for the preparation of polymer materials with appropriate particle size, suitable for cold pressing processes, and usable as battery binders in a simple manner.

[0005] In some embodiments, the step of mixing a polymer monomer, an initiator, and an emulsifier includes the steps of mixing the emulsifier with water to obtain a premix, and bringing the premix to a first temperature, adding the polymer monomer and the initiator drop by drop to the premix, and stirring to obtain the mixture. This premixing improves the dispersion uniformity of the reaction system and further improves the reaction yield.

[0006] In some embodiments, the mass ratio of the polymer monomer, the initiator, and the emulsifier in the mixture is 100:(0.2~1.2):(1~12). This can improve the polymer yield.

[0007] In some embodiments, the first temperature is 25°C to 95°C. This can improve the dispersion effect of the premix.

[0008] In some embodiments, the stirring process satisfies at least one of the following conditions: the time of the stirring process is 10 min to 360 min, and the rotation speed of the stirring process is 10 rpm to 100 rpm. Thereby, the uniformity of the premix can be further improved.

[0009] In some embodiments, the step of subjecting the mixture to a polymerization reaction includes a step of subjecting the mixture to a heat preservation treatment to obtain the polymer emulsion. Thereby, a polymer can be obtained by an emulsion polymerization reaction.

[0010] In some embodiments, the heat preservation treatment satisfies at least one of the following conditions: the time of the heat preservation treatment is 10 min to 480 min, and the temperature of the heat preservation treatment is 45 °C to 95 °C. Thereby, the reaction rate and reaction yield of the polymerization reaction can be improved.

[0011] In some embodiments, the granulation treatment includes a spray drying treatment. Thereby, the solid substance in the polymer emulsion can be dried into powder by the spray drying treatment.

[0012] In some embodiments, the spray drying treatment includes at least one of centrifugal spray drying, pneumatic spray drying, and pressure spray drying. Thereby, the yield of the granulation treatment and the dispersibility of the prepared particles can be improved.

[0013] In some embodiments, the centrifugal spray drying satisfies at least one of the following conditions: the inlet air temperature of the centrifugal spray drying is 60 °C to 280 °C, the outlet air temperature of the centrifugal spray drying is 40 °C to 100 °C, and the linear velocity of the atomizer of the centrifugal spray drying is 100 m / s to 500 m / s. Thereby, the yield of the granulation treatment can be further improved, and the particle size of the polymer can be effectively controlled.

[0014] In some embodiments, the airflow spray drying includes at least one of two-fluid spray drying, three-fluid spray drying, and four-fluid spray drying. This helps to obtain polymer particles with small particle sizes and improve the particle size uniformity.

[0015] In some embodiments, the two-fluid spray drying satisfies at least one of the conditions that the air pressure of the two-fluid spray drying is 0.1 MPa to 5 MPa and the liquid pressure of the two-fluid spray drying is 0.1 MPa to 100 MPa. This can further improve the particle size uniformity of the polymer particles.

[0016] In some embodiments, the three-fluid spray drying satisfies at least one of the conditions that the first air pressure of the three-fluid spray drying is 0.1 MPa to 5 MPa, the second air pressure of the three-fluid spray drying is 0.1 MPa to 5 MPa, and the liquid pressure of the three-fluid spray drying is 0.05 MPa to 50 MPa. This can improve the particle size uniformity of the polymer particles.

[0017] In some embodiments, the acrylate monomer includes at least one of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate, trifluoroethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, trimethylolpropane triacrylate, and trimethylaminoethyl methacrylate. This can obtain a polymer having a low glass transition temperature.

[0018] In some embodiments, the polymer monomer further comprises at least one of acrylic acid, methacrylic acid, butenic acid, heptenoic acid, acrylamide, N-hydroxymethylacrylamide and N-butoxymethylacrylamide, acrylonitrile, and methacrylonitrile. This can be advantageous for the polymer of the polymer monomer and for improving the binding properties and ionic conductivity of the polymer.

[0019] In some embodiments, the anionic emulsifier comprises at least one of sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfate, sodium laurate, sodium stearate, and sodium palmitoleate. This allows polymerization reactions to occur in an emulsion system.

[0020] In some embodiments, the initiator satisfies at least one of the following conditions: the persulfate initiator contains at least one of potassium persulfate and ammonium persulfate; the acyl peroxide initiator contains at least one of benzoyl peroxide and di-n-octanoyl peroxide; and the azo initiator contains at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate. This allows the initiator to initiate the polymerization reaction of monomers.

[0021] In some embodiments, the step of drying the polymer is further included. This can reduce the water content of the polymer.

[0022] In some embodiments, the step of grinding the polymer is further included. This makes it possible to obtain polymer particles with small particle size and a uniform and narrow particle size distribution.

[0023] In some embodiments, the grinding process includes at least one of jet mill grinding, mechanical mill grinding, sand mill grinding, and ball mill grinding. This makes it possible to obtain polymer particles of appropriate particle size.

[0024] In some embodiments, the classification linear velocity of the jet mill grinding is 10 m / s to 80 m / s. This improves the grinding effect of the grinding process.

[0025] In some embodiments, the grinding section of the mechanical mill comprises a rotor and a stator, and the grinding section satisfies at least one of the following conditions: (1) there is a gap between the rotor and the stator, with a gap width of 50 μm to 5000 μm; (2) the rotor has a conical structure composed of multiple sets of ceramic modules, the ceramic modules are toothed cutter sets, and the angle between the side line and the bottom line of the rotor is 65° to 80°; and (3) the stator is conical, a sawtooth ceramic lining is fitted to the outer surface of the stator, and the angle between the side line and the bottom line of the stator is 65° to 80°. This improves the grinding effect of the grinding process.

[0026] In some embodiments, the grinding medium for the sand mill grinding includes zirconia beads with a particle size of 0.1 mm to 3 mm. This improves the grinding effect of the grinding process.

[0027] In a second aspect of this application, the application proposes a polymer prepared by the method described above. This polymer possesses all the features and advantages of the method described above, and a detailed explanation is omitted here.

[0028] In some embodiments, the Dv50 particle size of the polymer is 2 μm to 50 μm. This allows it to be applied to a variety of application scenarios.

[0029] In some embodiments, the water content of the polymer powder is 3% or less. This is advantageous for long-term storage and use.

[0030] In some embodiments, the glass transition temperature of the polymer is 45°C or lower. This allows the polymer to exhibit a fluid state at a lower temperature.

[0031] In a third aspect of this application, the application proposes the use of a polymer prepared by the method described above as a binder. This allows the polymer to retain all the characteristics and advantages of the polymer when used as a binder, and a detailed explanation is omitted here.

[0032] In a fourth aspect of this application, the application proposes a separator comprising the polymer described above. This separator possesses all the characteristics and advantages of the polymer described above, and a detailed explanation is omitted here.

[0033] In a fifth aspect of this application, the application proposes a battery comprising the separator described above. This battery has all the features and advantages of the separator described above, and a detailed explanation is omitted here.

[0034] In a sixth aspect of this application, the application proposes an electrical device comprising the battery described above. This electrical device has all the features and advantages of the battery described above, and a detailed explanation is omitted here. [Brief explanation of the drawing]

[0035] The above and / or additional aspects and advantages of this application will be evident and easier to understand from the following description of the embodiments illustrated in the drawings.

[0036] [Figure 1] This is a schematic flowchart of a polymer preparation method according to one embodiment of this application. [Figure 2] This is a schematic flowchart of a polymer preparation method according to another embodiment of this application. [Figure 3]This is a schematic flowchart of a polymer preparation method according to another embodiment of this application. [Figure 4] This is a schematic flowchart of a polymer preparation method according to another embodiment of this application. [Figure 5] This is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 6] Figure 5 is an exploded view of a battery cell according to one embodiment of this application. [Figure 7] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 8] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 9] Figure 8 is an exploded view of a battery pack according to one embodiment of this application. [Figure 10] This is a schematic diagram of an electrical device powered by a battery according to one embodiment of this application. [Modes for carrying out the invention]

[0037] The embodiments of this application are described in detail below, with exemplary examples of such embodiments shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are illustrative and are for interpretation purposes only, and should not be construed as limiting this application.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those generally understood by those skilled in the art relating to this application. The terms used in this application are solely for the purpose of describing the specific embodiments and are not intended to limit this application. Unless otherwise specified, the numerical values ​​of each parameter mentioned in this application can be measured by various measurement methods commonly used in the art (for example, by the methods shown in the embodiments of this application).

[0039] The terms “including,” “having,” and any variations thereof in the specification and claims of this application are open-ended expressions, meaning they include the content shown in this application but do not exclude the content of other embodiments.

[0040] The “range” disclosed in this application is limited by a lower and upper limit, and a given range is limited by selecting one lower limit and one upper limit, and the boundaries of the special range are limited by the selected lower and upper limits. Such limited ranges may or may not include endpoint values ​​and can be combined arbitrarily, that is, any lower limit and any upper limit can be combined to form a single range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, the ranges 60-110 and 80-120 are also understood to be predictable. Similarly, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all predictable. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is merely an abbreviated representation of combinations of these numbers. Furthermore, when a parameter is described as being an integer of 2 or more, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technological solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0043] In the description of this application, terms such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly representing the number of technical features shown.

[0044] In the description of this application, “A and / or B” may include any one of the following: A alone, B alone, or A and B, where A and B are merely illustrative examples and may be any technical features linked by “and / or” in this application.

[0045] If the bonding force between the positive electrode sheet, negative electrode sheet, and separator is insufficient, gaps are more likely to form between the battery sheets and the separator, significantly increasing the battery's internal resistance and further reducing its cycle performance. By applying a binder to the surface of the separator, the problem of poor contact between the separator and the sheet can be improved. Taking polyvinylidene fluoride binder as an example, because there are voids in the structure of the separator and sheet, when the electrode assembly is pressurized by a hot press process, the temperature of the hot press process is higher than the glass transition temperature of the binder, allowing the binder to become soft and deformable by the pressing force. As the pressing force acts on the binder, some of the structure of the binder seeps into the voids in the separator and sheet, bonding the separator and the binder, creating a mechanical interlock effect and achieving bonding functionality. However, the high price of fluorine-containing binders significantly increases the cost of batteries. Furthermore, the hot-pressing process required for the polyvinylidene fluoride binder to tightly bond the separator and sheet reduces the production efficiency of batteries, resulting in excess energy consumption and failing to meet the requirements of battery production lines for increased production speed and reduced energy consumption.

[0046] To improve production speed and reduce energy consumption in battery production lines, there is a trend to use cold pressing processes instead of hot pressing processes to improve the bonding strength between the sheet and separator within existing battery processes. Specifically, the cold pressing process for battery sheets refers to a process that fixes the shape of the wound cells, reduces the elasticity of the cells, and improves the cell assembly pass rate and the consistency of the thickness of the finished cell product. Due to the low ambient temperature of the cold pressing process, a binder with a low glass transition temperature is required to achieve effective bonding between the sheet and separator. Acrylate polymers have a low glass transition temperature and can therefore be used as binders in cold pressing processes.

[0047] When polymer materials are synthesized by emulsion polymerization, granular polymer materials can be obtained by granulation. At the same time, because the particle size of polymers in emulsion-type acrylate polymers is 100 nm to 200 nm, direct knife coating to a separator can cause clogging or insufficient bonding strength due to the small particle size of the polymer. Granulation treatment is useful for obtaining polymers with larger particle sizes. When granulating acrylate polymer emulsions, the intermolecular forces of the acrylate polymers are strong, so phenomena such as particle aggregation often occur, making it difficult to granulate them properly.

[0048] In this application, by optimizing the raw material blending ratio of the acrylate polymer and the viscosity and solid content of the polymer emulsion, it is possible to obtain acrylate particles with appropriate particle size and low particle aggregation by granulating the primary particles in the acrylate polymer emulsion through a simple process to form secondary particle balls. When the acrylate polymer in this application is used as a binder on the separator surface, the separator has excellent affinity for the electrolyte and good impregnation of the separator by the electrolyte. That is, the separator wet length in the electrolyte is long, which is advantageous for the transport of metal-active ions, reduces the internal resistance of the battery, and makes the bond between the separator and the sheet tighter. This reduces polarization loss, extends the battery cycle life, and improves the battery utilization rate.

[0049] In a first aspect of this application, the application proposes a method for preparing polymers, which enables the simple preparation of polymer materials with appropriate particle size, suitable for cold pressing processes, and usable as battery binders. Referring to Figure 1, the method includes the following steps S100, S200, and S300.

[0050] In step S100, the polymer monomer, initiator, and emulsifier are mixed.

[0051] In some embodiments, the mixture is obtained in this step by mixing a polymer monomer, an initiator, and an emulsifier.

[0052] Regarding emulsifiers, they are substances that convert mutually immiscible oils and waters into emulsions that are difficult to separate into layers. Emulsifiers are generally surfactants that possess the properties of both hydrophilic polar groups and hydrophobic (lipophilic) nonpolar groups.

[0053] Regarding initiators, they are substances that can initiate the polymerization reaction of monomers. For example, a free radical initiator refers to a compound that readily generates free radicals (i.e., primary free radicals) through thermal decomposition, and can be used to initiate free radical polymerization and copolymerization reactions of olefin and diene monomers.

[0054] In some embodiments, mixing a polymer monomer, an initiator, and an emulsifier includes mixing the emulsifier with water to obtain a premix, and bringing the premix to a first temperature, adding the polymer monomer and initiator drop by drop to the premix, and stirring to obtain a mixture.

[0055] When an emulsifier is mixed with water, an emulsion can be formed; that is, the emulsifier forms micelles in the aqueous phase, and after the polymer is added, the polymer monomer and initiator are solubilized in most micelles, which facilitates the subsequent emulsion polymerization reaction.

[0056] In some embodiments, the first temperature may be 25°C to 95°C.

[0057] For example, the first temperature may be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.

[0058] Adding polymer monomers and initiators at the first temperature helps to solubilize the polymer monomers in micelles, thereby improving the efficiency of the polymer reaction.

[0059] In some embodiments, the stirring process can satisfy at least one of the following conditions: the stirring time may be 10 min to 360 min, and the stirring speed may be 10 rpm to 100 rpm.

[0060] In some embodiments, the polymer monomer may include acrylate monomers, the ester groups of which can improve the swelling resistance of the polymer, and as flexible monomer segments in the molecular segment, can regulate the glass transition temperature of the polymer, thus helping to adjust the glass transition temperature of the polymer to an appropriate range.

[0061] In some embodiments, the acrylate monomer includes at least one of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate, trifluoroethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, trimethylolpropane triacrylate, and trimethylaminoethyl methacrylate. This makes it possible to obtain polymers having a low glass transition temperature.

[0062] In some embodiments, the polymer may be a polymer obtained by polymerizing one type of monomer, for example, an acrylate-based polymer, or a copolymer obtained by polymerizing multiple types of monomers, for example, an acrylate-based copolymer.

[0063] Regarding copolymers, polymerization reactions in which two or more monomers participate together are called copolymerization reactions, and the resulting polymer contains two or more monomer units. Such polymers are called copolymers, or simply copolymers.

[0064] Regarding acrylate copolymers, they are a general term for polymers produced by copolymerizing acrylate monomers with other comonomers. Acrylate copolymers have good binding properties, and using them improves the binding performance between the separator and the sheet after cold pressing.

[0065] For example, the acrylate copolymer may be produced by copolymerizing an acrylate monomer with an olefin monomer, and the copolymer may include, for instance, an ethylene-methyl acrylate-glycidyl methacrylate ternary copolymer.

[0066] In some embodiments, the polymer monomer may further comprise at least one of acrylic acid, methacrylic acid, butenic acid, heptenoic acid, acrylamide, N-hydroxymethylacrylamide and N-butoxymethylacrylamide, acrylonitrile, and methacrylonitrile.

[0067] The unsaturated carboxyl groups in the polymer monomer are advantageous for monomer polymerization, and during the process of pressing the separator and sheet using a cold press process, the carboxyl groups can form bonding forces with functional groups in the sheet and separator materials, thereby improving the binding effect.

[0068] The unsaturated amide groups in polymer monomers can play a role in regulating molecular weight and also possess good binding properties.

[0069] Unsaturated cyano groups in polymer monomers help improve the ionic conductivity and binding properties of the polymer.

[0070] In some embodiments, the emulsifier may include an anionic emulsifier, which may include at least one of sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfate, sodium laurate, sodium stearate, and sodium palmitoleate.

[0071] In some embodiments, the initiator can satisfy at least one of the following conditions: the persulfate initiator comprises at least one of potassium persulfate and ammonium persulfate; the acyl peroxide initiator comprises at least one of benzoyl peroxide and di-n-octanoyl peroxide; and the azo initiator comprises at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

[0072] In some embodiments, the mass ratio of polymer monomer, initiator, and emulsifier in the mixture may be 100:(0.2~1.2):(1~12), which can improve the polymer yield.

[0073] In S200, the mixture is subjected to a polymerization reaction.

[0074] In some embodiments, the step involves heating the mixture while an initiator is used to initiate emulsion polymerization of monomers within the micelles to obtain a polymer emulsion.

[0075] Emulsion polymerization involves dispersing monomers in water with an emulsifier and mechanical stirring to form an emulsion, and then adding an initiator to initiate monomer polymerization.

[0076] In some embodiments, the viscosity of the polymer emulsion may be 100 mPa·s to 2000 mPa·s, and the solids content of the polymer emulsion may be 20% to 60%.

[0077] For example, the viscosity of polymer emulsions is 100 mPa·s, 150 mPa·s, 200 mPa·s, 250 mPa·s, 300 mPa·s, 350 mPa·s, 400 mPa·s, 450 mPa·s, 500 mPa·s, 550 mPa·s, 600 mPa·s, 650 mPa·s, 700 mPa·s, 750 mPa·s, 800 mPa·s, 850 mPa·s, 900 mPa·s, 950 mPa·s, 1000 mPa·s, 1050 mPa·s. It may also be s, 1100 mPa·s, 1150 mPa·s, 1200 mPa·s, 1250 mPa·s, 1300 mPa·s, 1350 mPa·s, 1400 mPa·s, 1450 mPa·s, 1500 mPa·s, 1550 mPa·s, 1600 mPa·s, 1650 mPa·s, 1700 mPa·s, 1750 mPa·s, 1800 mPa·s, 1850 mPa·s, 1900 mPa·s, 1950 mPa·s, or 2000 mPa·s.

[0078] For example, the solids content of the polymer emulsion may be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%.

[0079] For example, the viscosity of a polymer emulsion can be measured using a rotary Brookfield viscometer, specifically by measuring it at 25°C using a 62# rotor.

[0080] When the viscosity and solid content of the polymer emulsion are within the above range, it is advantageous for ejecting the polymer emulsion during the granulation process, thereby improving the effectiveness of the granulation process. If the viscosity and solid content of the polymer are outside the above range, ejection of the polymer emulsion becomes difficult, which is disadvantageous for granulation.

[0081] In some embodiments, the polymer emulsion may be subjected to a viscosity reduction treatment and / or the solids content of the polymer emulsion before granulation to satisfy the process requirements of a subsequent granulation treatment, such as a spray drying treatment.

[0082] In some embodiments, polymerizing a mixture involves subjecting the mixture to a heat-retaining treatment to obtain a polymer emulsion.

[0083] In some embodiments, the heat retention treatment satisfies at least one of the following conditions: the heat retention treatment time is 10 min to 480 min, and the heat retention treatment temperature is 45°C to 95°C. This can improve the reaction rate and reaction yield of the polymerization reaction.

[0084] In S300, the polymer emulsion is granulated.

[0085] In some embodiments, when polymer materials are synthesized by emulsion polymerization, it is necessary to obtain granular polymer materials by granulation, for example, to obtain a powder of the polymer material.

[0086] In some embodiments, the granulation process may include a spray drying process.

[0087] Spray drying is a granulation process in which a polymer emulsion is sprayed and dried by the action of heat. Specifically, spray drying involves three stages: atomization of the polymer emulsion, contact between the droplets and hot air, and gas-solid separation. The process conditions for spray drying must be adjusted accordingly to the viscosity and solid content of the polymer emulsion. For example, the inlet air temperature, outlet air temperature, and spray velocity of the spraying device must be appropriately controlled during spray drying. This allows for more favorable atomization of the polymer emulsion, improves the contact and mixing efficiency between the droplets and hot air, and further improves the yield of the spray drying process.

[0088] In some embodiments, the spray drying process may include at least one of centrifugal spray drying, airflow spray drying, and pressure spray drying.

[0089] In some embodiments, centrifugal spray drying can satisfy at least one of the following conditions: the inlet air temperature of the centrifugal spray dryer is 60°C to 280°C; the outlet air temperature of the centrifugal spray dryer is 40°C to 100°C; and the linear velocity of the sprayer of the centrifugal spray dryer is 100 m / s to 500 m / s.

[0090] In centrifugal spray drying, a centrifugal sprayer located at the top of the drying tower atomizes the polymer emulsion into fine mist droplets, which are then sprayed into a hot airflow by the atomization kinetic energy. The water in the mist droplets instantly vaporizes and evaporates, and is discharged from the drying tower body via an exhaust dust removal system. The dried powder product falls to the bottom of the tower, yielding a polymer material powder.

[0091] When the inlet air temperature for centrifugal spray drying is within the above range, a moderate amount of solvent remains after evaporation. This reduces the likelihood of the dried polymer material absorbing heat from the solvent and melting or decomposing, which can cause the product to adhere to the walls and become difficult to recover, or to alter the product's quality. Furthermore, it reduces the likelihood of the product caking and decreasing yield caused by excessive solvent concentration, which can lead to the polymer emulsion sticking to clumps or the walls.

[0092] When the outlet air temperature of centrifugal spray drying is within the above range, the dried or semi-dried polymer material is not protected by the solvent and therefore continuously absorbs heat, making it less likely for the polymer material to burn, melt, or decompose. In addition, because it is in a semi-dried state, it is less likely to stick together in clumps or accumulate and adhere to the bottom of the drying chamber.

[0093] When the linear velocity of the sprayer is within the above range, the amount of solvent that needs to evaporate from the mist droplets is appropriate, the amount of heat that needs to be absorbed is appropriate, and it is less likely that the droplets will adhere to the wall or form clumps.

[0094] In some embodiments, the airflow spray drying may include at least one of two-fluid spray drying, three-fluid spray drying, or four-fluid spray drying.

[0095] In some embodiments, two-fluid spray drying can satisfy at least one of the following conditions: the atmospheric pressure of the two-fluid spray drying is 0.1 MPa to 5 MPa, and the liquid pressure of the two-fluid spray drying is 0.1 MPa to 100 MPa. This can further improve the uniformity of the polymer particle size.

[0096] Two-fluid spray drying is a process in which a polymer emulsion and a gas pass through a two-fluid nozzle, causing the liquid to be ejected by a high-speed airflow to form mist-like or droplet-like liquid particles. The water is then instantly vaporized and evaporated by a hot airflow in the drying tower, and the dried powder product is discharged from the drying tower body via an exhaust dust removal system, falling to the bottom of the tower.

[0097] The operating principle of two-fluid spray drying can be divided into two parts: the airflow part and the liquid part. The airflow part involves accelerating the airflow to high speed using compressed air or another gas, then ejecting it through the nozzle outlet, where the airflow forms a high-speed beam, and this beam ejects the polymer emulsion. The liquid part involves injecting the polymer emulsion into the airflow beam through the liquid outlet of the nozzle, during which the polymer emulsion is sheared into small particles, forming a mist or droplet-like liquid.

[0098] In some embodiments, three-fluid spray drying can satisfy at least one of the following conditions: the first atmospheric pressure of the three-fluid spray drying is 0.1 MPa to 5 MPa; the second atmospheric pressure of the three-fluid spray drying is 0.1 MPa to 5 MPa; and the liquid pressure of the three-fluid spray drying is 0.05 MPa to 50 MPa. This makes it possible to improve the particle size uniformity of polymer particles.

[0099] In some embodiments, three-fluid spray drying and four-fluid spray drying are similar in principle to two-fluid spray drying, differing only in the nozzle structure, namely, mixing the airflow and liquid at the nozzle outlet through different pipes to form a polymer emulsion into mist or droplet-like liquids.

[0100] Because acrylate polymer emulsions have a tendency to absorb water, when an acrylate polymer is coated on the separator surface, the moisture in the polymer increases the internal resistance of the battery, causing it to decompose during the charge-discharge cycle, generating gas and leading to many defects such as battery swelling. Therefore, the water content in the polymer can be reduced by drying.

[0101] In some embodiments, referring to Figure 2, the polymer preparation method may further include the following step S500.

[0102] In S500, the polymer is subjected to a drying process.

[0103] In some embodiments, the water content of the polymer can be reduced by drying during this step.

[0104] In some embodiments, the freezing step can freeze a wet material, such as a polymer containing a certain amount of moisture, into a solid state at a low temperature, and then sublimate the moisture within it directly into a gaseous state without passing through a liquid state under vacuum. Pure cold-press separator binders have properties such as a low glass transition temperature (Tg) and a tendency to absorb water. To further reduce the water content of the binder and facilitate mechanical grinding and granulation, this solution further freeze-dries the binder after spray drying by a freezing process, and by controlling the freezing temperature, vacuum level, and time, bound and unbound water can be further removed, reducing the water content and simultaneously decreasing the tackiness of the solid binder.

[0105] In some embodiments, the drying process includes a freeze-drying process, which satisfies at least one of the following conditions: the freeze-drying temperature may be (-1)°C to (-80)°C; the freeze-drying time may be 2 hours to 50 hours; and the vacuum level of the freeze-drying process may be 2 Pa to 45 Pa.

[0106] When polymer materials obtained by granulation treatment of acrylate-based polymer emulsions still experience phenomena such as aggregation and solidification, and when there are high requirements for the particle size of the polymer material, grinding treatment can alleviate the aggregation and solidification phenomena of the polymer and improve the particle size uniformity of the polymer material.

[0107] In some embodiments, referring to Figure 3, the polymer preparation method may further include the following step S400.

[0108] In S400, the polymer is subjected to a pulverizing process.

[0109] In some embodiments, the step involves grinding to obtain polymer particles with small particle size, uniform particle size distribution, and a narrow shape.

[0110] In some embodiments, the grinding process may include at least one of jet mill grinding, mechanical mill grinding, sand mill grinding, and ball mill grinding.

[0111] In some embodiments, the classification linear velocity of the jet mill grinding may be 10 m / s to 80 m / s.

[0112] Jet milling is a process in which compressed air, after being cooled, filtered, and dried, is injected into a grinding chamber as a supersonic airflow through a nozzle, fluidizing the material. Within the grinding chamber, the accelerated material converges at the point where the airflows from multiple nozzles meet, resulting in intense collisions, friction, and shearing, which achieves ultrafine particle grinding. During airflow grinding granulation, it is necessary to control parameters such as grinding pressure, gas consumption, and material supply particle size.

[0113] In some embodiments, the grinding section of a mechanical mill can consist of a rotor and a stator, and the grinding section satisfies at least one of the following conditions: there is a gap between the rotor and the stator, with a gap width of 50 μm to 5000 μm; the rotor is a conical structure composed of multiple sets of ceramic modules, the ceramic modules are toothed cutter sets, and the angle between the side line and the bottom line of the rotor is 65° to 80°; and the stator is conical, with a sawtooth ceramic lining fitted to the outer surface of the stator, and the angle between the side line and the bottom line of the stator is 65° to 80°.

[0114] The width of the gap between the rotor and the stator, or the spacing, can be changed by adjusting the number and thickness of the spacers.

[0115] The rotor may have a conical structure composed of three sets of ceramic modules. Specifically, each of the three sets of ceramic modules constituting the rotor is a toothed cutter set, where the uppermost toothed cutter set may consist of 90 cutters, thereby performing coarse grinding, and the middle and lowermost toothed cutter sets may consist of 120 cutters, thereby performing fine grinding.

[0116] Mechanical milling is a method of grinding materials by applying intense impact to them using a rotating body (such as a sledgehammer, hammer, or plate) that rotates at supersonic speeds around a horizontal or vertical axis, causing collisions with a stationary body or with other particles. During mechanical grinding, it is necessary to control parameters such as the diameter and rotational speed of the rotor.

[0117] In some embodiments, the grinding medium for sand mill grinding may include zirconia beads, and the particle size of the zirconia beads may be 0.1 mm to 3 mm.

[0118] Sand milling is a process in which a solid-liquid phase mixture, which has been pre-dispersed and wetted using a stirrer, is introduced into a cylindrical body by a material pump. The material and the grinding medium inside the cylindrical body are then agitated together by a high-speed rotating disperser, generating intense collisions, friction, and shearing forces between the solid particles in the material and the grinding medium. This process accelerates the grinding of the particles and disperses aggregates. After grinding and dispersion, the material is separated from the grinding medium by a dynamic separator and discharged through a discharge pipe.

[0119] Ball milling is a process of gradually grinding a material to a desired particle size through friction and abrasion between steel balls and the material inside the ball mill body. The operation of a ball mill is generally divided into two stages: grinding and classification.

[0120] In some embodiments, as shown in Figure 4, the polymer can be frozen to below its glass transition temperature or embrittlement temperature by freeze-drying, and then pulverized.

[0121] Under low-temperature conditions, the hardness and brittleness of the polymer increase. During the cooling process, various parts of the polymer contract unevenly, generating internal stress. This stress causes microcracks to form in weaker areas of the polymer, reducing the bonding strength of the internal structure. As a result, even a small external force can rapidly propagate these internal cracks, leading to fracture.

[0122] For example, in a grinding process, liquid nitrogen can be selected as a cooling source. The temperature of liquid nitrogen can reach (-196)°C, which can be adjusted to match the brittle point of the polymer. By using liquid nitrogen as a medium, ultra-low temperature grinding can be achieved, reducing explosions and oxidation.

[0123] In the above-described method, the order in which each step is described is not a strict execution order and does not impose any restrictions on the implementation process. Those skilled in the art will understand that the specific execution order of each step should depend on its function and possible inherent logic.

[0124] In a second aspect of this application, the application proposes a polymer prepared by the method described above. This polymer possesses all the features and advantages of the method described above, and a detailed explanation is omitted here.

[0125] In some embodiments, the Dv50 particle size of the polymer may be 2 μm to 50 μm.

[0126] For example, the Dv50 particle size of a polymer can be measured using a laser particle size analyzer (Malvern 3000, MasterSizer 3000), with a helium-neon red light source as the primary light source. Take a clean, small beaker, add 1 g of the sample to be measured, add 1 drop of surfactant, add 20 ml of deionized water, and sonicate at 53 kHz / 120 W for 5 minutes to completely disperse the sample. Start the laser particle size analyzer, clean the optical path system, and then perform background measurement automatically. Stir the sonicated sample solution to disperse it uniformly, place it in the sample cell as needed, and begin measuring the particle size. The measurement results can be read from the instrument.

[0127] In some embodiments, the Dv50 particle size of the polymer after grinding may be 2 μm to 10 μm.

[0128] In some embodiments, the water content of the polymer powder is 3% or less.

[0129] For example, for measuring the water content of polymer powders, you can refer to Method A / Oven Method in "GB / T 2914-2008 Measurement of Volatile Matter (Including Water) of Plastics / Vinyl Chloride Homopolymers and Copolymer Resins," using a sample amount of 5g.

[0130] In some embodiments, the water content of the polymer powder after drying may be 2% or less.

[0131] In some embodiments, the glass transition temperature of the polymer is 45°C or lower.

[0132] In some embodiments, the glass transition temperature of the polymer may be 35°C or lower. This allows the polymer to exhibit a fluid state at a lower temperature.

[0133] For example, the following can be used to measure the glass transition temperature of a polymer. A sample of 6 ± 0.05 mg is weighed and placed in an aluminum crucible, shaken flat, and then the lid is placed on. The temperature is then measured using a Netzsch DSC 3500 Sirius instrument. The atmosphere is nitrogen, the purge gas rate is 50 mL / min, the protective gas rate is 100 mL / min, and the heating conditions are a heating rate of 10 °C / min and a temperature range of (-70) °C to 200 °C.

[0134] The glass transition temperature is the temperature at which a high polymer transitions from a highly elastic state to a glassy state. It refers to the transition temperature of an amorphous polymer (including the amorphous portion in a crystalline polymer) from a glassy state to a highly elastic state, or vice versa. It is the lowest temperature at which the polymer segments of an amorphous polymer can move freely, and is generally expressed as Tg. Above the glass transition temperature, high polymers exhibit elasticity and a certain degree of fluidity, but below the glass transition temperature, high polymers exhibit brittleness. The glass transition temperature can be measured by methods commonly used in this field; for example, it can be measured by differential scanning calorimetry, referring to GB / T19466.2.

[0135] In a third aspect of this application, the application proposes the use of a polymer prepared by the method described above as a binder. This allows the polymer to retain all the characteristics and advantages of the polymer when used as a binder, and a detailed explanation is omitted here.

[0136] In some embodiments, the polymer can be used as a binder on the surface of the base film in the separator.

[0137] In a fourth aspect of this application, the application proposes a separator comprising the polymer described above. This separator possesses all the characteristics and advantages of the polymer described above, and a detailed explanation is omitted here.

[0138] In some embodiments, the separator includes a separator and a binding layer located on at least one side of the base film, the binding layer may contain the polymer described above.

[0139] In some embodiments, when the above-described polymer is coated onto the base film surface as a binder, the polymer is not tacky at a certain temperature, making it easy to wind and unwind the separator. Furthermore, when a cold pressing process is performed after winding together with the positive and negative electrode sheets, the polymer has suitable bonding strength, causing both the positive and negative electrode sheets to bond tightly to each other with the separator. By coating the base film of the separator with the above-described binder, the bonding performance between the sheets and the binder is improved, which can alleviate the edge peeling problem in the preliminary cold pressing process of the cell, thereby improving the hardness of the electrode assembly and the cycle characteristics of the battery.

[0140] In this application, the type of separator is not particularly limited, and any porous structure separator having good chemical stability and mechanical stability can be selected.

[0141] In some embodiments, the base film material includes at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0142] In a fifth aspect of this application, the application proposes a battery comprising the separator described above. This battery has all the features and advantages of the separator described above, and a detailed explanation is omitted here.

[0143] Typically, a battery pack includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During charging and discharging of the battery, active ions repeatedly insert and remove between the positive and negative electrode sheets. The electrolyte plays a role in conducting active ions between the positive and negative electrode sheets. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes of the battery, while also allowing ions to pass through.

[0144] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector.

[0145] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode active material layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0146] In some embodiments, as the positive electrode current collector, a metal foil or a composite current collector can be used. For example, as the metal foil, aluminum 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 base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material base (such as a base of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0147] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material can be a positive electrode active material for a lithium-ion battery known in the art.

[0148] As an example, the positive electrode active material may include at least one of lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (NCM211 (Can also be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (Can also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (It can also be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (for example, LiNi 0.85 Co 0.15 Al 0.05 The material may contain, but is not limited to, at least one of O2) and modified compounds thereof. Examples of lithium-containing phosphates with an olivine structure may include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composite materials, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composite materials, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composite materials. The modified compounds of each of the above materials may be obtained by doping and / or surface coating modification of the material.

[0149] During the charging and discharging process of a battery, the molar content of Li differs when the battery is discharged to different states due to the insertion, removal, and consumption of Li. In the enumeration of positive electrode active materials in this application, the molar content of Li is the initial state of the material, i.e., the state before material input. After the positive electrode active material is used in a battery system and undergoes charge-discharge cycles, the molar content of Li changes.

[0150] In some embodiments, when the battery is a sodium-ion battery, the positive electrode active material can be any positive electrode active material known in the art for sodium-ion batteries.

[0151] For example, the positive electrode active material may include at least one of sodium transition metal oxides, polyanionic compounds, Prussian blue-based sodium compounds, and modified compounds of each thereof. However, this application is not limited to these materials, and other conventional materials usable as positive electrode active materials for batteries may be used. The modified compounds of each of the above materials may be obtained by doping and / or surface coating modification of the materials.

[0152] In some embodiments, the transition metal in the sodium transition metal oxide may be at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu. The chemical formula of the sodium transition metal oxide is Na x It can satisfy MO2, where M contains at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, Cu, and 0 <x≦1である。

[0153] In some embodiments, the polyanionic compound is a sodium ion, a transition metal ion, and a tetrahedral (YO4) ion. n- The compound may have an anionic unit. Here, the transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may include at least one of P, S, and Si, and n is (YO4) n- It represents the valence.

[0154] In some embodiments, the polyanionic compound is a sodium ion, a transition metal ion, or a tetrahedral (YO4) ion. n- The compound may have an anionic unit and a halogen anion. The transition metal may contain at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may contain at least one of P, S, and Si, and n is (YO4) n- This represents the valency, and the halogen may contain at least one of F, Cl, or Br.

[0155] In some embodiments, the polyanionic compound is a sodium ion, tetrahedral (YO4) n- Anion unit, polyhedral unit (ZO y ) m+ and may be compounds having selectable halogen anions. M may comprise at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, Y may comprise at least one of P, S and Si, and n is (YO4) n- This represents the valency, Z represents the transition metal, and m is (ZO y ) m+ This represents the valency, and the halogen may contain at least one of F, Cl, and Br.

[0156] For example, polyanionic compounds have the chemical formulas NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (M' contains at least one of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y It can satisfy at least one of the conditions (0 ≤ y ≤ 1).

[0157] In some embodiments, the Prussian blue compound contains sodium ions, transition metal ions, and cyanide ions (CN - The compound may have ). The transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce.

[0158] For example, Prussian blue compounds have the chemical formula Na a Me b Me' c (CN)6 can be satisfied, provided that Me and Me' each independently contain at least one of Ni, Cu, Fe, Mn, Co, and Zn, and 0 <a≦2、0<b<1、0<c<1である。

[0159] During the charging and discharging process of a battery, the molar content of Na differs when the battery is discharged to different states due to the insertion, removal, and consumption of Na. In the enumeration of positive electrode active materials in this application, the molar content of Na is the initial state of the material, i.e., the state before material input. After the positive electrode active material is used in a battery system and undergoes charge-discharge cycles, the molar content of Na changes.

[0160] In the enumeration of positive electrode active materials in this application, the molar content of oxygen is merely a theoretical value, and the molar content of oxygen changes due to oxygen release from the lattice, causing the actual molar content of oxygen to fluctuate.

[0161] In some embodiments, the positive electrode active material layer further selectively comprises a binder.

[0162] For example, the binder may include at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0163] In some embodiments, the positive electrode active material layer further selectively contains a conductive agent.

[0164] For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0165] In some embodiments, the positive electrode sheet can be manufactured as follows: The above components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, the positive electrode slurry is coated onto a positive electrode current collector, and after processes such as oven drying and cold pressing, a positive electrode sheet can be obtained.

[0166] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the negative electrode active material layer containing a negative electrode active material.

[0167] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode active material layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0168] In some embodiments, a metal foil or a composite current collector can be used as the negative electrode current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0169] In some embodiments, the negative electrode active material can be any negative electrode active material known in the art for batteries. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based materials may include at least one of elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based materials include at least one of elemental tin, tin oxygen compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials usable as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more types.

[0170] In some embodiments, the negative electrode active material layer selectively further comprises a binder. The binder comprises 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).

[0171] In some embodiments, the negative electrode active material layer selectively further comprises a conductive agent. The conductive agent comprises at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0172] In some embodiments, the negative electrode active material layer selectively further comprises other additives, such as a thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0173] In some embodiments, the negative electrode sheet can be manufactured as follows: The above-mentioned components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, the negative electrode slurry is coated onto a negative electrode current collector, and after processes such as oven drying and cold pressing, a negative electrode sheet can be obtained.

[0174] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. In this application, the type of electrolyte is not specifically limited and can be selected as needed. For example, the electrolyte may be liquid, gel-like, or all-solid.

[0175] In some embodiments, an electrolyte solution is used. The electrolyte solution contains an electrolyte salt and a solvent.

[0176] In some embodiments, the electrolyte salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0177] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethylmethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0178] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may further include additives that can improve certain aspects of the battery's performance, such as additives that can improve the battery's overcharge performance, or additives that can improve the battery's high-temperature or low-temperature performance.

[0179] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be assembled into an electrode assembly by a winding process or a lamination process.

[0180] In some embodiments, the battery may include an casing. This casing can be used to enclose the electrode assembly and electrolyte.

[0181] In some embodiments, the battery casing may be a rigid case such as a hard plastic case, an aluminum case, or a steel case. The battery casing may also be a soft pack such as a pouch-type soft pack. The material of the soft pack may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0182] In this application, the shape of the battery is not particularly limited and may be cylindrical, rectangular, or any other shape. For example, Figure 5 shows a rectangular battery cell 5 as an example.

[0183] In some embodiments, referring to Figure 6, the casing may include a case 51 and a top cover assembly 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround the casing to form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the top cover assembly 53 can cover the opening and seal the housing cavity. The positive electrode sheet, negative electrode sheet and separator can be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is sealed within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and a person skilled in the art can select one according to specific practical requirements.

[0184] In some embodiments, the batteries may be assembled as a battery module, and the number of batteries included in the battery module may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0185] Figure 7 shows an example of a battery module 4. Referring to Figure 7, in the battery module 4, the multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple battery cells 5 may be fixed by fastening members.

[0186] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of battery cells 5 are housed.

[0187] In some embodiments, the battery modules may be assembled as a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0188] Figures 8 and 9 show an example of a battery pack 1. Referring to Figures 8 and 9, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper box 2 and a lower box 3, and the upper box 2 is covered by the lower box 3 and can form a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0189] In a sixth aspect of this application, the application proposes an electrical device comprising the battery described above. This electrical device possesses all the features and advantages of the battery described above, and a detailed explanation is omitted here.

[0190] Batteries, battery modules, or battery packs may be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0191] As for the electrical device, a battery, battery module, or battery pack can be selected according to the requirements of its use.

[0192] Figure 10 shows an example of an electrical device. This electrical device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the requirements for high power output and high energy density of the battery, the electrical device may use a battery pack or battery module.

[0193] Other examples of devices may include mobile phones, tablet computers, and laptop computers. These devices are typically required to be lightweight and thin, and may use batteries as a power source.

[0194] Examples of the present application are described below. The examples described below are illustrative and are for interpretive purposes only, and should not be understood as limiting this application. Unless otherwise specified in the examples, specific techniques or conditions are followed in accordance with the techniques or conditions or product specifications described in the literature in the art. Unless otherwise specified, the reagents or equipment used are common commercially available products.

[0195] Example 1 Emulsion synthesis The monomers consisted of 65 wt% n-butyl acrylate, 5 wt% trimethylolpropane triacrylate, 2 wt% acrylic acid, 3 wt% 2-hydroxyethyl acrylate, 20 wt% acrylonitrile, and 5 wt% acrylamide. The initiator was ammonium persulfate, and the emulsifier was sodium dodecyl sulfate. The mass ratio of monomers, initiator, and emulsifier was 100:1:1.

[0196] All emulsifiers, monomers accounting for 30% of the total monomer mass, and initiators accounting for 30% of the total initiator mass were added to the reaction vessel, water was added and the mixture was stirred at a stirring speed of 30 rpm. After stirring at room temperature for 1 hour, the temperature was raised to 60°C within 1 hour. The stirring speed was maintained at 30 rpm, and the remaining monomers and initiators were added to the reaction vessel at a uniform rate over 3 hours. After adding all the materials, the mixture was kept warm for 4 hours, and the pH was adjusted to 5-8 to obtain a polymer emulsion. The viscosity of the polymer emulsion at 25°C was 1500 mPa·s, the weight ratio of water to other components in the polymer emulsion was 50:50, and the solids content of the polymer emulsion was 50%.

[0197] Centrifugal spray drying The polymer emulsion was transferred to a centrifugal spray buffer stirring tank, and the stirring tank was set to a rotation speed of 60 rpm. After stirring for 2 hours, the material formulation was complete. The spray dryer was started, with the inlet air temperature set to 200°C, the outlet air temperature to 80°C, and the sprayer rotation speed set to 15,000 rpm (spray disc diameter 180 mm, corresponding linear velocity 141 m / s). After stabilization, the material supply pump was started, with a material supply rate of 2,000 kg / h. The slurry was dried by the centrifugal spray dryer, and polymer powder was obtained.

[0198] Example 2 Example 2 is identical to Example 1, but differs in that the polymer powder from Example 1 is transported to the hopper of the jet mill, the jet mill is started, the pressure of the grinding gas is adjusted to 5 bar, the linear velocity of the classification wheel is adjusted to 38.6 m / s (classification wheel diameter 315, rotation speed 3000 rpm), and the material is collected by a dust collector to obtain the polymer after grinding.

[0199] Example 3 Example 3 differs from Example 1 in that the monomer in Example 3 contains 40 wt% methyl methacrylate, 40 wt% lauryl methacrylate, 3 wt% acrylic acid, 2 wt% 2-hydroxyethyl acrylate, 5 wt% trimethylolpropane triacrylate, and 20 wt% acrylonitrile, and the viscosity of the polymer emulsion at 25°C is 100 mPa·s.

[0200] Example 4 Example 4 differs from Example 1 in that the monomer in Example 4 contains 60 wt% n-butyl acrylate, 5 wt% trimethylolpropane triacrylate, 2 wt% acrylic acid, 8 wt% 2-hydroxyethyl acrylate, and 25 wt% acrylonitrile, and the viscosity of the polymer emulsion at 25°C is 1000 mPa·s.

[0201] Example 5 Example 5 differs from Example 1 in that the monomer in Example 5 contains 60 wt% n-butyl acrylate, 5 wt% trimethylolpropane triacrylate, 2 wt% acrylic acid, 8 wt% 2-hydroxyethyl acrylate, 15 wt% acrylonitrile, and 10 wt% acrylamide, and the viscosity of the polymer emulsion at 25°C is 2000 mPa·s.

[0202] Example 6 Example 6 differs from Example 1 in that the weight ratio of water to other components in the polymer emulsion is 80:20, and the solids content of the polymer emulsion is 20%.

[0203] Example 7 Example 7 differs from Example 1 in that the weight ratio of water to other components in the polymer emulsion is 60:40, and the solid content of the polymer emulsion is 40%.

[0204] Example 8 Example 8 differs from Example 1 in that the weight ratio of water to other components in the polymer emulsion is 40:60, and the solids content of the polymer emulsion is 60%.

[0205] Comparative Example 1 Comparative Example 1 differs from Example 1 in that the monomer in Comparative Example 1 contains 55 wt% ethyl acrylate, 5 wt% trimethylolpropane triacrylate, and 40 wt% acrylonitrile, and the viscosity of the polymer emulsion at 25°C is 80 mPa·s.

[0206] Comparative Example 2 Comparative Example 2 differs from Example 1 in that the monomer in Comparative Example 2 contains 55 wt% ethyl acrylate, 5 wt% trimethylolpropane triacrylate, 20 wt% acrylonitrile, and 20 wt% acrylamide, and the viscosity of the polymer emulsion at 25°C is 2100 mPa·s.

[0207] Comparative Example 3 Comparative Example 3 differs from Example 1 in that the ratio of water to other components is 82:18 and the solid content of the polymer emulsion is 18%.

[0208] Comparative Example 4 Comparative Example 2 differs from Comparative Example 4 in that the ratio of water to other components is 39:61, and the solid content of the polymer emulsion is 61%.

[0209] The polymers from Examples 1-8 and Comparative Examples 1-4 were placed in a separator and assembled as a battery, specifically as follows.

[0210] Manufacturing of separators A commercially available PE microporous thin film (derived from Zhuoga Electronics Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 80 nm was used as the base film. The polymer prepared as described above was stirred in deionized water to uniformly mix it and obtain a slurry (solid content 20%). The slurry was spray-coated onto two surfaces of the substrate, dried to remove the solvent, and the coating density of the coating composition on the substrate was set to 1.5 g / m². 2 Thus, a separator was obtained.

[0211] Manufacturing of positive electrode sheets A positive electrode slurry was prepared by thoroughly stirring and uniformly mixing polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), the conductive agent carbon black, and N-methylpyrrolidone (NMP) in a mass ratio of 1.2:58.38:0.42:40. The slurry was then applied at a density of 200 g / m³. 2 The positive electrode current collector's aluminum foil was uniformly coated with the specified amount of material, and then oven-dried, cold-pressed, and cut to obtain the positive electrode sheet.

[0212] Manufacturing of negative electrode sheets Artificial graphite, acetylene black (a conductive agent), styrene-butadiene rubber (SBR) (a binder), and sodium carboxymethylcellulose (CMC-Na) (a thickener) were added to deionized water in a mass ratio of 96.2:1.0:1.6:1.2, and thoroughly stirred to mix uniformly to prepare a negative electrode slurry. The negative electrode slurry was then applied at a concentration of 98 g / m². 2 The copper foil of the negative electrode current collector was coated with the specified amount of material, and then the negative electrode sheet was obtained by oven drying, cold pressing, and cutting.

[0213] Preparation of electrolyte At 25°C, ethylene carbonate (EC), ethylmethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent. Then, LiPF6 was dissolved in the above mixed solvent to obtain an electrolyte, at which point the concentration of LiPF6 was 1 mol / L.

[0214] Battery manufacturing The positive electrode sheet, separator, and negative electrode sheet were stacked in order and wound together, and a cell was obtained by cold press molding (during which the separator and sheets bond together). The cell was placed in an outer casing, the electrolyte prepared above was added, and after processes such as sealing, standing, chemical conversion, and aging were performed, a secondary battery was obtained.

[0215] The polymers, separators, and batteries in Examples 1-8 and Comparative Examples 1-4 were measured as follows, and the measurement results are shown in Table 1.

[0216] The measurement method is as follows:

[0217] 1. Viscosity of polymer emulsion: Measured using a rotational Brookfield viscometer, specifically using a #62 rotor at 25°C.

[0218] 2. Solid content of polymer emulsion: The solid content was measured using a halogen moisture meter (Mettler HE 53), with a sample volume of 1 g and a temperature of 120°C.

[0219] 3. Measurement of the glass transition temperature (Tg) of polymers A sample of 6 ± 0.05 mg was weighed, placed in an aluminum crucible, shaken flat, and then covered. Measurement was performed using a Netzsch DSC 3500 Sirius instrument. The atmosphere was nitrogen, with a purge gas rate of 50 mL / min and a protective gas rate of 100 mL / min. The heating conditions were a heating rate of 10 °C / min and a temperature range of -70 to 200 °C.

[0220] 4. Measurement of polymer particle size Measurements were performed using a laser particle size analyzer (Malvern 3000, MasterSizer 3000), with a helium-neon red light source as the primary light source. A clean, small beaker was taken, 1 g of the sample to be measured was added, one drop of surfactant was added, and 20 ml of deionized water was added. The sample was then ultrasonically treated at 53 kHz / 120 W for 5 minutes to completely disperse it. After starting the laser particle size analyzer and cleaning the optical path system, background measurements were performed automatically. The ultrasonically treated sample solution was stirred to uniformly disperse it, and then, as required, it was placed in a sample cell, and particle size measurement began. The measurement results can be read from the instrument.

[0221] 5. Moisture content of polymer powder: Refer to Method A / Oven method of "GB / T 2914-2008 Measurement of Volatile Matter (including water) of Plastics / Vinyl Chloride Homopolymers and Copolymer Resins," and use a sample amount of 5 g.

[0222] 6. Wet length of the separator: The separator was cut into a sample measuring 5 mm in width and 100 mm in length. After fixing both ends of the sample, it was left to stand horizontally. 0.5 mg of electrolyte was dropped into the center of the sample, and after 1 minute, a photograph was taken to measure the electrolyte diffusion length, thereby obtaining the wet length of the separator. To ensure the accuracy of the measurement results, 10 samples were taken and measured, and the average value was calculated to obtain the measurement results. The electrolyte can be prepared by the following method: Ethylene carbonate (EC), ethylmethyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 30:50:20 to obtain an organic solvent, and thoroughly dried LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0223] 7. Battery Cycle Characteristics: At 25°C, the manufactured battery is charged with a constant current of 1 / 3C up to 3.65V, then charged with a constant voltage of 3.65V until the current drops to 0.05C, left for 5 minutes, then discharged at 1 / 3C down to 2.0V. The resulting discharge capacity is denoted as the initial capacity C0. The above steps are repeated for the same battery, and simultaneously, the discharge capacity C of the battery after n cycles is recorded. n The battery capacity retention rate P after each cycle is recorded. n =C n / C0 × 100%, and the battery capacity retention rate P after 500 cycles. 500 The cycle characteristics are represented using this method.

[0224] [Table 1]

[0225] As can be seen from Table 1, in Comparative Example 1, the viscosity of the polymer emulsion was too low, resulting in the prepared polymer having a glass transition temperature that was too low, poor electrolyte resistance, poor bonding stability of the bonding coating layer formed on the base film surface by the polymer, and consequently, poor battery cycle characteristics. In Comparative Example 2, the viscosity of the polymer emulsion was too high, resulting in the prepared polymer having a Dv50 diameter that was too large, the bonding coating layer formed on the base film surface by the polymer being too thick, poor electrolyte impregnation of the separator, and consequently, poor battery cycle characteristics. In Comparative Example 3, the solid content of the polymer emulsion was too low, increasing energy consumption during production, the powder water content of the prepared polymer powder was too high, making the polymer prone to aggregation, poor coating quality of the bonding coating layer formed on the base film surface by the polymer, poor bonding stability of the bonding coating layer, and consequently, poor battery cycle characteristics. In Comparative Example 4, the solid content of the polymer emulsion was too high, resulting in an excessively large Dv50 diameter of the prepared polymer, a thick binding coating layer formed on the base film surface by the polymer, poor electrolyte impregnation of the separator, and consequently, poor battery cycle characteristics.

[0226] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and all embodiments having substantially the same technical idea and achieving the same function and effect within the scope of the technical solution of this application are included in the technical scope of this application. Furthermore, other forms that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included in the scope of this application, without departing from the gist of this application. [Explanation of Symbols]

[0227] 1 Battery pack 2. Top box 3. Lower box 4 Battery Modules 5 battery cells 51 cases 52 Electrode assembly 53 Top cover assembly

Claims

1. A step of mixing a polymer monomer, an initiator, and an emulsifier to obtain a mixture, wherein the polymer monomer includes an acrylate monomer, the initiator includes at least one of a persulfate initiator, an acyl peroxide initiator, and an azo initiator, and the emulsifier includes an anionic emulsifier, A step of polymerizing the mixture to obtain a polymer emulsion, wherein the viscosity of the polymer emulsion at 25°C is 100 mPa·s to 2000 mPa·s, and the solid content of the polymer emulsion is 20% to 60%. A method for preparing a polymer, comprising the step of granulating the polymer emulsion to obtain a polymer.

2. The step of mixing polymer monomers, initiators, and emulsifiers is, The steps include: mixing the emulsifier with water to obtain a premix; The steps include: bringing the premix to a first temperature, adding the polymer monomer and the initiator to the premix drop by drop, and stirring to obtain the mixture; The method for preparing a polymer according to claim 1, wherein selectively, the mass ratio of the polymer monomer, the initiator, and the emulsifier in the mixture is 100:(0.2-1.2):(1-12).

3. The method for preparing a polymer according to claim 2, wherein the first temperature is 25°C to 95°C.

4. The aforementioned stirring process is The duration of the aforementioned stirring process is 10 min to 360 min, A method for preparing a polymer according to claim 2 or 3, wherein at least one of the following conditions is met: the rotation speed of the stirring process is 10 rpm to 100 rpm.

5. The step of causing the mixture to undergo a polymerization reaction is, A method for preparing a polymer according to any one of claims 1 to 4, comprising the step of heat-treating the mixture to obtain the polymer emulsion.

6. The aforementioned heat retention treatment is The duration of the aforementioned heat retention treatment is 10 min to 480 min, The method for preparing a polymer according to claim 5, wherein the temperature of the heat retention treatment is 45°C to 95°C, and at least one of these conditions is met.

7. The method for preparing a polymer according to any one of claims 1 to 6, wherein the granulation treatment includes a spray drying treatment.

8. The method for preparing a polymer according to claim 7, wherein the spray drying treatment includes at least one of centrifugal spray drying, airflow spray drying, and pressure spray drying.

9. The aforementioned centrifugal spray drying is The inlet air temperature of the centrifugal spray drying system is 60°C to 280°C, The outlet air temperature of the centrifugal spray drying system is 40°C to 100°C, The method for preparing a polymer according to claim 8, wherein at least one of the following conditions is met: the linear velocity of the sprayer in the centrifugal spray drying is 100 m / s to 500 m / s.

10. The method for preparing a polymer according to claim 8, wherein the airflow spray drying includes at least one of two-fluid spray drying, three-fluid spray drying, and four-fluid spray drying.

11. The aforementioned two-fluid spray drying is The atmospheric pressure for the two-fluid spray drying is 0.1 MPa to 5 MPa, A method for preparing a polymer according to claim 10, wherein at least one of the following conditions is met: the liquid pressure of the two-fluid spray drying is 0.1 MPa to 100 MPa.

12. The aforementioned three-fluid spray drying is The first atmospheric pressure for the three-fluid spray drying is 0.1 MPa to 5 MPa, The second atmospheric pressure for the three-fluid spray drying is 0.1 MPa to 5 MPa, A method for preparing a polymer according to claim 10, wherein the liquid pressure of the three-fluid spray drying is 0.05 MPa to 50 MPa, and at least one of these conditions is met.

13. The initiator is The persulfate initiator contains at least one of potassium persulfate and ammonium persulfate, The acyl peroxide initiator comprises at least one of benzoyl peroxide and di-n-octanoyl peroxide, A method for preparing a polymer according to any one of claims 1 to 12, wherein the azo initiator contains at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

14. The method for preparing a polymer according to any one of claims 1 to 13, wherein the acrylate monomer comprises at least one of methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate, trifluoroethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, trimethylolpropane triacrylate, and trimethylaminoethyl methacrylate.

15. A method for preparing a polymer according to any one of claims 1 to 14, wherein the polymer monomer further comprises at least one of acrylic acid, methacrylic acid, butenic acid, heptenoic acid, acrylamide, N-hydroxymethylacrylamide and N-butoxymethylacrylamide, acrylonitrile, and methacrylonitrile.

16. The method for preparing a polymer according to any one of claims 1 to 15, wherein the anionic emulsifier comprises at least one of sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfate, sodium laurate, sodium stearate, and sodium palmitoleate.

17. A method for preparing a polymer according to any one of claims 1 to 16, further comprising the step of drying the polymer.

18. A method for preparing a polymer according to any one of claims 1 to 17, further comprising the step of grinding the polymer.

19. The method for preparing a polymer according to claim 18, wherein the grinding treatment includes at least one of jet mill grinding, mechanical mill grinding, sand mill grinding, and ball mill grinding.

20. The method for preparing a polymer according to claim 19, wherein the classification linear speed of the jet mill grinding is 10 m / s to 80 m / s.

21. The grinding section of the aforementioned mechanical mill comprises a rotor and a stator. The aforementioned crushing section is (1) There is a gap between the rotor and the stator, and the width of the gap is 50 μm to 5000 μm, (2) The rotor has a conical structure composed of multiple sets of ceramic modules, the ceramic modules are tooth-profile cutter sets, and the angle between the side line and the bottom line of the rotor is 65° to 80°. (3) The method for preparing a polymer according to claim 19, which satisfies at least one of the following conditions: the stator is conical, a sawtooth ceramic lining is fitted to the outer surface of the stator, and the angle between the side line and the bottom line of the stator is 65° to 80°.

22. The method for preparing a polymer according to claim 19, wherein the grinding medium for the sand mill grinding comprises zirconia beads having a particle size of 0.1 mm to 3 mm.

23. A polymer prepared by the polymer preparation method according to any one of claims 1 to 22.

24. The polymer according to claim 23, wherein the Dv50 particle size of the polymer is 2 μm to 50 μm.

25. The polymer according to claim 23 or 24, wherein the water content of the polymer powder is 3% or less.

26. The polymer according to any one of claims 23 to 25, wherein the glass transition temperature of the polymer is 45°C or lower.

27. Use as a binder for a polymer prepared by the polymer preparation method according to any one of claims 1 to 22.

28. A separator comprising the polymer according to any one of claims 23 to 26.

29. A battery comprising the separator described in claim 28.

30. An electrical device comprising the battery described in claim 29.

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