Preparation method of polymer, polymer, application of polymer, diaphragm, battery and electric device

Abstract

The invention discloses a polymer preparation method, a polymer and application thereof, a diaphragm, a battery and an electric device, the polymer preparation method comprises the following steps: mixing a polymer monomer, an initiator and an emulsifier to obtain a mixture, the polymer monomer comprising an acrylate monomer; the initiator comprises at least one of a persulfate initiator, an acyl peroxide initiator and an azo initiator; the emulsifier comprises an anionic emulsifier; the mixture is subjected to a polymerization reaction, polymer emulsion is obtained, the viscosity of the polymer emulsion at the temperature of 25 DEG C ranges from 100 mPa.s to 2000 mPa.s, and the solid content of the polymer emulsion ranges from 20% to 60%; and carrying out granulation treatment on the polymer emulsion to obtain the polymer. Therefore, the polymer material which is moderate in particle size, suitable for a cold pressing process and capable of being used as a battery binder can be prepared through a simple and convenient method.

Description

Technical Field

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

[0002] In recent years, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. Binders, as inactive materials in batteries, are used to bond the components in the battery slurry and adjacent battery components together. The amount and cost of binders in batteries are very small, but they can effectively improve battery performance. On the premise of meeting the bonding performance, the binder also needs to be able to withstand the swelling and corrosion of the electrolyte, as well as withstand electrochemical corrosion during charging and discharging. Therefore, there are fewer types of polymers that can be used as battery binders, and polymers that meet the requirements also have problems such as cumbersome manufacturing processes, low yields, and limited application scenarios. Current polymers and their preparation methods still need to be further improved.

[0003] It should be noted that the above statements are only used to provide background technical information related to the present application and do not necessarily constitute prior art. Summary of the invention

[0004] In the first aspect of the present application, the present application proposes a method for preparing a polymer, comprising: 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; the emulsifier comprises an anionic emulsifier; the mixture is polymerized to obtain a polymer emulsion, wherein the viscosity of the polymer emulsion at 25°C is 100mPa·s-2000mPa·s, and the solid content of the polymer emulsion is 20%-60%; the polymer emulsion is granulated to obtain the polymer. Thus, a polymer material with moderate particle size, suitable for cold pressing process, and usable as a battery binder can be obtained by a simple method.

[0005] In some embodiments, the step of mixing the polymer monomer, the initiator, and the emulsifier includes: mixing the emulsifier with water to obtain a premix; bringing the premix to a first temperature, adding the polymer monomer and the initiator dropwise to the premix, and stirring the premix to obtain the mixture. Thus, the dispersion uniformity of the reaction system can be improved by premixing, thereby improving 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). Thus, the yield of the polymer can be improved.

[0007] In some embodiments, the first temperature is 25° C.-95° C. Thus, the dispersion effect of the premix can be improved.

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

[0009] In some embodiments, the step of causing the mixture to undergo a polymerization reaction comprises: subjecting the mixture to a heat preservation treatment to obtain the polymer emulsion. Thus, a polymer can be obtained through an emulsion polymerization reaction.

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

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

[0012] In some embodiments, the spray drying process includes at least one of centrifugal spray drying, airflow spray drying, and pressure spray drying, thereby improving the yield of the granulation process and the dispersibility of the obtained particles.

[0013] In some embodiments, the centrifugal spray drying satisfies at least one of the following conditions: the air inlet temperature of the centrifugal spray drying is 60°C-280°C; the air outlet temperature of the centrifugal spray drying is 40°C-100°C; the atomizer linear speed of the centrifugal spray drying is 100m / s-500m / s. Thus, the yield of the granulation process 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, thereby helping to obtain polymer particles with smaller particle sizes and improving particle size uniformity.

[0015] In some embodiments, the two-fluid spray drying satisfies at least one of the following conditions: the air pressure of the two-fluid spray drying is 0.1 MPa-5 MPa; the hydraulic pressure of the two-fluid spray drying is 0.1 MPa-100 MPa. Thus, the particle size uniformity of the polymer particles can be further improved.

[0016] In some embodiments, the three-fluid spray drying satisfies at least one of the following conditions: the first air pressure of the three-fluid spray drying is 0.1 MPa-5 MPa; the second air pressure of the three-fluid spray drying is 0.1 MPa-5 MPa; the hydraulic pressure of the three-fluid spray drying is 0.05 MPa-50 MPa. Thus, the particle size uniformity of the polymer particles can be improved.

[0017] In some embodiments, the acrylic acid ester 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 trimethylamineethyl methacrylate. Thus, a polymer with a relatively low glass transition temperature can be obtained.

[0018] In some embodiments, the polymer monomer further includes at least one of acrylic acid, methacrylic acid, crotonic acid, heptenoic acid, acrylamide, N-hydroxymethyl acrylamide and N-butoxymethyl acrylamide, acrylonitrile, and methacrylonitrile. This can be beneficial to the polymerization of the polymer monomer and improve the adhesion and ionic conductivity of the polymer.

[0019] In some embodiments, the anionic emulsifier includes at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, sodium laurate, sodium stearate, and sodium palmitoleate. Thus, the polymerization reaction can be carried out in an emulsion system.

[0020] In some embodiments, the initiator satisfies at least one of the following conditions: the persulfate initiator includes at least one of potassium persulfate and ammonium persulfate; the acyl peroxide initiator includes at least one of benzoyl peroxide and dioctanoyl peroxide; the azo initiator includes at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate. Thus, the monomer can be initiated to undergo polymerization reaction by the initiator.

[0021] In some embodiments, the method further comprises: drying the polymer, thereby reducing the water content of the polymer.

[0022] In some embodiments, the method further comprises: pulverizing the polymer, thereby obtaining polymer particles with smaller particle size and uniform and narrow particle size distribution.

[0023] In some embodiments, the pulverization process includes at least one of air flow milling, mechanical milling, sand milling, and ball milling, thereby obtaining polymer particles with a moderate particle size.

[0024] In some embodiments, the classification linear velocity of the jet mill is 10 m / s-80 m / s, thereby improving the pulverizing effect of the pulverizing process.

[0025] In some embodiments, the pulverizing part of the mechanical mill includes a rotor and a stator, and the pulverizing part satisfies at least one of the following conditions: (1) there is a gap between the rotor and the stator, and the width of the gap is 50 μm-5000 μm; (2) the rotor is a conical structure composed of multiple groups of ceramic modules, and the ceramic modules are toothed knife groups, and the angle between the side line and the bottom line of the rotor is 65°-80°; (3) the stator is conical, and the outer surface of the stator is embedded with a serrated ceramic lining, and the angle between the side line and the bottom line of the stator is 65°-80°. In this way, the pulverizing effect of the pulverizing process can be improved.

[0026] In some embodiments, the grinding media of the sand mill includes zirconium oxide beads, and the particle size of the zirconium oxide beads is 0.1 mm-3 mm. Thus, the pulverization effect of the pulverization process can be improved.

[0027] In the second aspect of the present application, the present application provides a polymer, which is prepared by the aforementioned method. Therefore, the polymer has all the characteristics and advantages of the aforementioned method, which will not be described in detail here.

[0028] In some embodiments, the polymer has a Dv50 particle size of 2 μm-50 μm, which can be applied to a variety of application scenarios.

[0029] In some embodiments, the water content of the polymer powder is less than or equal to 3%, which is conducive to long-term storage and use.

[0030] In some embodiments, the glass transition temperature of the polymer is less than or equal to 45° C. Thus, the polymer can exhibit a fluid state at a relatively low temperature.

[0031] In the third aspect of the present application, the present application proposes the use of the polymer prepared by the aforementioned method as a binder. Therefore, when the polymer is used as a binder, it has all the characteristics and advantages of the aforementioned polymer, which will not be repeated here.

[0032] In a fourth aspect of the present application, the present application proposes a membrane, comprising the aforementioned polymer. Thus, the membrane has all the characteristics and advantages of the aforementioned polymer, which will not be described in detail here.

[0033] In the fifth aspect of the present application, the present application proposes a battery, comprising the aforementioned separator. Therefore, the battery has all the features and advantages of the aforementioned separator, which will not be described in detail here.

[0034] In the sixth aspect of the present application, the present application proposes an electrical device, comprising the aforementioned battery. Therefore, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0036] Figure 1 is a schematic flow chart of a method for preparing a polymer according to one embodiment of the present application;

[0037] Figure 2 is a schematic flow chart of a method for preparing a polymer according to another embodiment of the present application;

[0038] Figure 3 is a schematic flow chart of a method for preparing a polymer according to another embodiment of the present application;

[0039] Figure 4 is a schematic flow chart of a method for preparing a polymer according to another embodiment of the present application;

[0040] Figure 5 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0041] Figure 6 yes Figure 5 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0042] Figure 7is a schematic diagram of a battery module according to an embodiment of the present application;

[0043] Figure 8 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0044] Fig. 9 yes Figure 8 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0045] Fig.10 Schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0046] Description of reference numerals:

[0047] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell;

[0048] 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0049] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0050] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0051] The terms "including" and "having" in the specification and claims of the present application and any modifications thereof are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0052] " Scope " disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be to include end values ​​or not include end values, and can be combined arbitrarily, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when 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.

[0053] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0054] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0055] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. "First feature" and "second feature" may include one or more of the features.

[0056] In the description of the present application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for examples and may be any technical feature connected by "and / or" in the present application.

[0057] When the bonding force between the positive electrode sheet, the negative electrode sheet and the diaphragm is insufficient, a gap is easily formed between the battery's electrode sheet and the diaphragm, which significantly increases the internal resistance of the battery, thereby causing the battery cycle performance to deteriorate. The problem of poor contact between the diaphragm and the electrode sheet can be improved by setting a binder on the surface of the diaphragm. Taking polyvinylidene fluoride binder as an example, since there are pores in the structure of the diaphragm and the electrode sheet, when the electrode assembly is pressed by a hot pressing process, since the temperature of the hot pressing process is greater than the glass transition temperature of the binder, the binder can be in a softer state and can be deformed with the extrusion force. As the extrusion force acts on the binder, part of the structure of the binder can penetrate into the pores of the diaphragm and the electrode sheet, bonding the diaphragm and the binder together, playing a mechanical interlocking effect, and realizing the bonding function. However, the price of fluorine-containing binders is relatively high, which will significantly increase the cost of the battery. At the same time, polyvinylidene fluoride binders require a hot pressing process to make the diaphragm and the electrode sheet bonded tightly, which will reduce the production efficiency of the battery and generate additional energy consumption, which cannot meet the needs of speeding up the production of battery production lines and reducing energy consumption.

[0058] In order to achieve speed-up and energy-saving of battery production lines, the hot pressing process is gradually being replaced by the cold pressing process, so as to improve the bonding force between the pole piece and the diaphragm with the help of the original battery process. Specifically, the cold pressing process of the battery pole piece refers to the process of shaping the wound battery cell to reduce the elasticity of the battery cell, improve the qualified rate of the core installation and the consistency of the thickness of the finished battery cell. Since the ambient temperature of the cold pressing process is relatively low, an adhesive with a lower glass transition temperature is required to achieve effective bonding between the pole piece and the diaphragm. Acrylic polymers can be used as adhesives for the cold pressing process because of their lower glass transition temperature.

[0059] When synthesizing polymer materials through emulsion polymerization, granulation can be used to obtain granular polymer materials. At the same time, since the particle size of the polymer in the emulsion-type acrylic polymer is 100nm-200nm, if it is directly scraped onto the diaphragm, it will cause pore blockage or insufficient adhesion due to the small particle size of the polymer. Granulation can also help to obtain polymers with larger particle sizes. When granulating the acrylic polymer emulsion, due to the strong intermolecular force of the acrylic polymer, there are often phenomena such as particle agglomeration, which makes it difficult to granulate well.

[0060] In the present application, by optimizing the raw material ratio of the acrylic polymer and the viscosity and solid content of the polymer emulsion, the primary particles in the acrylic polymer emulsion can be granulated to form secondary particle balls through a relatively simple process, and acrylic particles with moderate particle size and less agglomeration between particles can be obtained. When the acrylic polymer in the present application is used as a binder on the surface of the diaphragm, the diaphragm has a better affinity for the electrolyte, and the electrolyte has a better wettability to the diaphragm, that is, the diaphragm wetting length in the electrolyte is longer, which is more conducive to the transmission of metal active ions, and the internal resistance of the battery is smaller. At the same time, the diaphragm and the pole piece are more closely attached, which can reduce polarization loss, extend the cycle life of the battery, and improve the utilization rate of the battery.

[0061] In the first aspect of the present application, the present application proposes a method for preparing a polymer, so that a polymer material with moderate particle size, suitable for cold pressing process, and usable as a battery binder can be prepared by a simple method. Figure 1 ,include:

[0062] S100: Mixing polymer monomers, initiators, and emulsifiers

[0063] In some embodiments, in this step, a mixture is obtained by mixing a polymer monomer, an initiator, and an emulsifier.

[0064] Emulsifiers are substances that can transform incompatible oil and water into an emulsion that is difficult to separate. Emulsifiers are usually surfactants that have both hydrophilic polar groups and hydrophobic (lipophilic) non-polar groups.

[0065] Initiator: An initiator is a substance that can initiate polymerization of monomers. For example, free radical initiators refer to a class of compounds that are easily decomposed into free radicals (i.e., primary free radicals) by heat, and can be used to initiate free radical polymerization and copolymerization of olefin and diene monomers.

[0066] In some embodiments, mixing the polymer monomer, the initiator, and the emulsifier includes: mixing the emulsifier with water to obtain a premix; allowing the premix to be at a first temperature, adding the polymer monomer and the initiator dropwise to the premix, and stirring to obtain a mixture.

[0067] Emulsifier and water can be mixed to form an emulsion, that is, the emulsifier forms micelles in the water phase. After the polymer is added, most of the micelles will be solubilized with polymer monomers and initiators, which will help the subsequent emulsion polymerization reaction to occur.

[0068] In some embodiments, the first temperature may be between 25°C and 95°C.

[0069] As an 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.

[0070] By adding the polymer monomer and the initiator at the first temperature to help solubilize the polymer monomer in the micelles, the efficiency of the polymer reaction can be improved.

[0071] In some embodiments, the stirring process may satisfy at least one of the following conditions: the stirring process time may be 10 min-360 min; the stirring process rotation speed may be 10 rpm-100 rpm.

[0072] In some embodiments, the polymer monomer may include an acrylate monomer. The ester group of the acrylate monomer can improve the anti-swelling ability of the polymer and, as a flexible monomer segment in the molecular segment, can adjust the glass transition temperature of the polymer, thereby helping to adjust the glass transition temperature of the polymer within a suitable range.

[0073] In some embodiments, the acrylic acid ester 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 trimethylamineethyl methacrylate. Thus, a polymer with a relatively low glass transition temperature can be obtained.

[0074] In some embodiments, the polymer may be a polymer formed by polymerizing one monomer, for example, an acrylate polymer; or may be a copolymer formed by polymerizing multiple monomers, for example, an acrylate copolymer.

[0075] Copolymer, the polymerization reaction in which two or more monomers participate together is called copolymerization. The polymer formed contains two or more monomer units. This type of polymer is called copolymer or interpolymer.

[0076] Acrylate copolymers are a general term for polymers produced by copolymerization of acrylate monomers and other comonomers. Acrylate copolymers have good adhesion. The use of acrylate copolymers makes the adhesion between the diaphragm and the pole piece better after cold pressing.

[0077] As an example, the acrylic ester copolymer may be copolymerized by acrylic ester monomers and olefin monomers. For example, the copolymer may include ethylene-methyl acrylate-glycidyl methacrylate terpolymer.

[0078] In some embodiments, the polymer monomer may further include at least one of acrylic acid, methacrylic acid, crotonic acid, heptenoic acid, acrylamide, N-hydroxymethyl acrylamide and N-butoxymethyl acrylamide, acrylonitrile, and methacrylonitrile.

[0079] The unsaturated carboxyl group in the polymer monomer is conducive to the polymerization of the monomer, so that in the process of pressing the diaphragm and the electrode using the cold pressing process, the carboxyl group can form a bonding force with the functional groups on the electrode and the diaphragm material, thereby improving the bonding effect.

[0080] The unsaturated amide group in the polymer monomer can play a role in regulating the molecular weight and also has good adhesion.

[0081] The unsaturated cyano group in the polymer monomer helps to improve the ionic conductivity and adhesion of the polymer.

[0082] In some embodiments, the emulsifier may include an anionic emulsifier, wherein the anionic emulsifier may include at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, sodium laurate, sodium stearate, and sodium palmitoleate.

[0083] In some embodiments, the initiator may satisfy at least one of the following conditions: the persulfate initiator includes at least one of potassium persulfate and ammonium persulfate; the acyl peroxide initiator includes at least one of benzoyl peroxide and dioctanoyl peroxide; the azo initiator includes at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

[0084] In some embodiments, the mass ratio of the polymer monomer, the initiator, and the emulsifier in the mixture can be 100:(0.2-1.2):(1-12), thereby increasing the yield of the polymer.

[0085] S200: Allow the mixture to polymerize

[0086] In some embodiments, in this step, the initiator is used to initiate emulsion polymerization of the monomers inside the micelles while heating the mixture to obtain a polymer emulsion.

[0087] Emulsion polymerization is a process in which monomers are dispersed in water with the help of emulsifiers and mechanical stirring to form an emulsion, and then an initiator is added to initiate the polymerization of the monomers.

[0088] In some embodiments, the viscosity of the polymer emulsion may be 100 mPa·s-2000 mPa·s, and the solid content of the polymer emulsion may be 20%-60%.

[0089] As an example, the viscosity of the polymer emulsion can be 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. a·s, 1100mPa·s, 1150mPa·s, 1200mPa·s, 1250mPa·s, 1300mPa·s, 1350mPa·s, 1400mPa·s, 1450mPa·s, 1500mPa·s, 155 0mPa·s, 1600mPa·s, 1650mPa·s, 1700mPa·s, 1750mPa·s, 1800mPa·s, 1850mPa·s, 1900mPa·s, 1950mPa·s or 2000mPa·s.

[0090] As an example, the solids content of the polymer emulsion may be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60%.

[0091] As an example, the viscosity of the polymer emulsion can be tested using a rotary Brookfield viscometer, specifically, using a 62# rotor at 25°C.

[0092] When the viscosity and solid content of the polymer emulsion are within the aforementioned ranges, it is beneficial to eject the polymer emulsion during the granulation process, thereby improving the effect of the granulation process. When the viscosity and solid content of the polymer are not within the aforementioned ranges, it is difficult to eject the polymer emulsion, which is not conducive to granulation.

[0093] In some embodiments, in order to meet the process requirements of subsequent granulation treatment, such as spray drying treatment, the polymer emulsion may be subjected to viscosity reduction treatment and / or the solid content of the polymer emulsion may be adjusted before the granulation treatment.

[0094] In some embodiments, allowing the mixture to undergo a polymerization reaction includes: subjecting the mixture to a heat-insulating treatment to obtain a polymer emulsion.

[0095] In some embodiments, the heat preservation treatment satisfies at least one of the following conditions: the heat preservation treatment time is 10 min-480 min; the heat preservation treatment temperature is 45° C.-95° C. Thus, the reaction rate and reaction yield of the polymerization reaction can be improved.

[0096] S300: Granulation of polymer emulsion

[0097] In some embodiments, when the polymer material is synthesized by emulsion polymerization, a granulation process is required to obtain a granular polymer material, for example, to obtain a powder of the polymer material.

[0098] In some embodiments, the granulation process may include a spray drying process.

[0099] Spray drying is a granulation process in which a polymer emulsion is sprayed and dried under the action of heat. Specifically, spray drying includes three stages: atomization of the polymer emulsion, contact between the droplets and hot air, and gas-solid separation. The process conditions of spray drying need to be adjusted accordingly according to the viscosity and solid content of the polymer emulsion. For example, during spray drying, it is necessary to control the appropriate inlet air temperature, outlet air temperature, and spray speed of the spray device so that the polymer emulsion can be better atomized, improve the contact and mixing efficiency between the droplets and the hot air, and thus improve the yield of the spray drying process.

[0100] In some embodiments, the spray drying process may include at least one of centrifugal spray drying, air flow spray drying, and pressure spray drying.

[0101] In some embodiments, centrifugal spray drying can meet at least one of the following conditions: the inlet air temperature of the centrifugal spray drying is 60°C-280°C; the outlet air temperature of the centrifugal spray drying is 40°C-100°C; the atomizer linear speed of the centrifugal spray drying is 100m / s-500m / s.

[0102] Centrifugal spray drying uses a centrifugal atomizer located at the top of the drying tower to atomize the polymer emulsion into fine mist droplets, which are sprayed into the hot air flow relying on the kinetic energy of atomization. The moisture in the mist droplets is instantly vaporized and evaporated, and discharged from the drying tower by the exhaust and dust removal system. The dry powder product falls to the bottom of the tower to obtain the powder of the polymer material.

[0103] When the air inlet temperature of the centrifugal spray drying is within the above range, the solvent residue after volatilization is moderate, and the dried polymer material is not easy to melt or decompose due to absorbing heat from the solvent, resulting in product sticking to the wall and being unable to collect the material or product deterioration. It is also not easy to cause concentration and viscosity due to excessive solvent, and then the polymer emulsion will stick to the wall or the wall, resulting in product agglomeration and reduced yield.

[0104] When the outlet air temperature of the centrifugal spray drying is within the above range, the polymer material in a dry or semi-dry state is not likely to continue to absorb heat due to the lack of solvent protection, causing the polymer material to become coke, melt or decompose, nor will it stick together or aggregate at the bottom of the drying chamber due to being still in a semi-dry state.

[0105] When the linear velocity of the atomizer is within the above range, the amount of solvent that needs to be evaporated by the mist droplets is moderate, the amount of heat that needs to be absorbed is moderate, and the mist droplets are not likely to stick to the wall or form agglomerates.

[0106] In some embodiments, the airflow spray drying may include at least one of two-fluid spray drying, three-fluid spray drying, and four-fluid spray drying.

[0107] In some embodiments, the two-fluid spray drying can meet at least one of the following conditions: the air pressure of the two-fluid spray drying is 0.1 MPa-5 MPa; the hydraulic pressure of the two-fluid spray drying is 0.1 MPa-100 MPa. Thus, the particle size uniformity of the polymer particles can be further improved.

[0108] Two-fluid spray drying refers to the process of passing polymer emulsion and gas through a two-fluid nozzle, using high-speed airflow to spray the liquid to form mist or droplet-shaped liquid particles. The hot air flow in the drying tower instantly vaporizes and evaporates the water, which is then discharged from the drying tower by the exhaust and dust removal system, and the dry powder product falls to the bottom of the tower.

[0109] The working principle of two-fluid spray drying can be divided into two parts: the air flow part and the liquid part. The air flow part refers to accelerating the air flow to a high speed through compressed air or other gases, and then spraying it out through the outlet of the nozzle. At the outlet of the nozzle, the air flow will form a high-speed air flow beam, and the air flow beam will spray the polymer emulsion; the liquid part refers to the polymer emulsion passing through the liquid outlet of the nozzle and spraying it into the air flow beam. In this process, the polymer emulsion will be sheared into small particles to form mist or droplet-like droplets.

[0110] In some embodiments, the three-fluid spray drying can meet at least one of the following conditions: the first air pressure of the three-fluid spray drying is 0.1 MPa-5 MPa; the second air pressure of the three-fluid spray drying is 0.1 MPa-5 MPa; the hydraulic pressure of the three-fluid spray drying is 0.05 MPa-50 MPa. Thus, the particle size uniformity of the polymer particles can be improved.

[0111] In some embodiments, the principles of three-fluid spray drying, four-fluid spray drying and two-fluid spray drying are similar, except that the nozzle structure is different, that is, the air flow and liquid are mixed at the nozzle outlet through different pipes to form mist or droplet-like droplets of the polymer emulsion.

[0112] Since acrylic polymer emulsions themselves have the characteristic of easily absorbing water, when acrylic polymers are coated on the surface of the diaphragm, the moisture in the polymer will cause the internal resistance of the battery to increase, and decompose to produce gas during the charge and discharge cycle, which will lead to many defects such as battery bulging. Therefore, the water content in the polymer can be reduced by drying treatment.

[0113] In some embodiments, reference Figure 2 , the method for preparing the polymer may further comprise:

[0114] S500: Drying of polymers

[0115] In some embodiments, in this step, the water content of the polymer may be reduced by drying.

[0116] In some embodiments, the wet material, such as a polymer containing a certain amount of water, can be frozen into a solid state at a relatively low temperature through a freezing step, and then the water therein can be sublimated directly into a gaseous state without passing through a liquid state under vacuum. Pure cold-pressed diaphragm binders have the characteristics of a low glass transition temperature Tg and easy water absorption. In order to further reduce the water content of the binder and facilitate mechanical crushing and granulation, this solution further freeze-dries the spray-dried binder through a freezing process, controls the freezing temperature, vacuum degree and time, and can further remove bound water and unbound water. At the same time, the water content is reduced, which also reduces the viscosity of the solid binder.

[0117] In some embodiments, the drying process includes freeze-drying process, and the freeze-drying process satisfies at least one of the following conditions: the temperature of the freeze-drying process can be (-1)°C-(-80)°C; the time of the freeze-drying process can be 2h-50h; the vacuum degree of the freeze-drying process can be 2Pa-45Pa.

[0118] After the granulation treatment of the acrylic polymer emulsion, the obtained polymer material still has the phenomenon of agglomeration and caking. When the particle size requirement of the polymer material is high, the agglomeration and caking phenomenon in the polymer can be alleviated by pulverization treatment, thereby improving the particle size uniformity of the polymer material.

[0119] In some embodiments, reference Figure 3 , the method for preparing the polymer may further comprise:

[0120] S400: Pulverizing polymers

[0121] In some embodiments, in this step, a pulverization process is performed to obtain polymer particles with smaller particle size and uniform and narrow particle size distribution.

[0122] In some embodiments, the pulverization process may include at least one of air flow milling, mechanical milling, sand milling, and ball milling.

[0123] In some embodiments, the classifying linear velocity of the jet mill may be 10 m / s to 80 m / s.

[0124] Airflow milling refers to the process in which compressed air is cooled, filtered, dried, and then injected into the grinding chamber through a nozzle to form a supersonic airflow, so that the material is fluidized. In the grinding chamber, the accelerated material converges at the intersection of the jet airflows of several nozzles, resulting in violent collision, friction, and shearing to achieve ultra-fine grinding of particles. When airflow grinding and granulation, it is necessary to control the parameters such as grinding pressure, gas consumption, and feed particle size. Airflow grinding requires the control of parameters such as grinding pressure and gas consumption.

[0125] In some embodiments, the crushing part of the mechanical mill can be composed of a rotor and a stator, and the crushing part satisfies at least one of the following conditions: there is a gap between the rotor and the stator, and the width of the gap is 50μm-5000μm; the rotor is a conical structure composed of multiple groups of ceramic modules, the ceramic module is a toothed knife group, and the angle between the side line and the bottom line of the rotor is 65°-80°; the stator is conical, and the outer surface of the stator is embedded with a serrated ceramic lining, and the angle between the side line and the bottom line of the stator is 65°-80°.

[0126] The gap width between the rotor and the stator, i.e. the spacing, can be changed by adjusting the number and thickness of the spacers.

[0127] The rotor can be a conical structure composed of three groups of ceramic modules. Specifically, the three groups of ceramic modules constituting the rotor are all toothed knife groups, among which the topmost toothed knife group can be composed of 90 knives to achieve the effect of coarse crushing, and the middle and bottom toothed knife groups can be composed of 120 knives to achieve the effect of fine crushing.

[0128] Mechanical grinding uses a rotating body (cup, hammer, plate, etc.) rotating at supersonic speed around a horizontal or vertical axis to violently impact the material, causing it to collide with a fixed body or with particles, thereby grinding the material. When mechanical grinding, it is necessary to control parameters such as the diameter of the rotor and the speed of the rotor.

[0129] In some embodiments, the grinding media of the sand mill may include zirconium oxide beads, and the particle size of the zirconium oxide beads may be 0.1 mm to 3 mm.

[0130] Sand mill uses a material pump to input the solid-liquid phase mixture that has been pre-dispersed and wetted by a mixer into the cylinder. The material and the grinding media in the cylinder are stirred by a high-speed rotating disperser, so that the solid particles in the material and the grinding media produce stronger collision, friction and shearing effects with each other, achieving the purpose of accelerating the grinding of particles and dispersing aggregates. The ground and dispersed material is separated from the grinding media by a dynamic separator and flows out from the discharge pipe.

[0131] Ball milling is to grind the material gradually to the required particle size through the friction and wear between the steel balls and the material in the mill. The working process of the ball mill is generally divided into two stages: grinding and grading.

[0132] In some embodiments, reference Figure 4 The polymer can be frozen to below the glass transition temperature or brittle temperature by freeze-drying, and then pulverized by crushing.

[0133] Under low temperature conditions, the hardness and brittleness of polymers increase, and during the cooling process, uneven shrinkage occurs at various locations inside the polymer, generating internal stress. Under the action of this stress, microcracks appear in weak locations inside the polymer, reducing the bonding strength of the internal structure. As a result, the internal cracks rapidly expand and break under a relatively small external force.

[0134] As an example, during the crushing process, liquid nitrogen can be used as a cold source. The temperature of liquid nitrogen can reach (-196)°C, so it can be adjusted according to the brittle point of the polymer. Using liquid nitrogen as a medium can achieve ultra-low temperature crushing, reduce explosion and oxidation, etc.

[0135] Those skilled in the art will appreciate that, in the specific implementation of the above method, the order in which the steps are written does not imply a strict order of execution, and thus does not constitute any limitation on the implementation process. The specific order of execution of the steps should be determined by their function and possible internal logic.

[0136] In the second aspect of the present application, the present application provides a polymer, which is prepared by the above method. Therefore, the polymer has all the characteristics and advantages of the above method, which will not be described in detail here.

[0137] In some embodiments, the polymer may have a Dv50 particle size of 2 μm to 50 μm.

[0138] As an example, the Dv50 particle size of a polymer can be tested using a laser particle size analyzer (Malvern 3000, MasterSizer 3000), with a helium-neon red light source as the main light source. Take a clean small beaker and add 1g of the sample to be tested, add a drop of surfactant, add 20ml of deionized water, and ultrasonicate at 53KHz / 120W for 5min to ensure that the sample is completely dispersed. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the ultrasonicated solution to be tested to make it evenly dispersed, put it into the sample cell as required, and start measuring the particle size. The measurement results can be read from the instrument.

[0139] In some embodiments, the Dv50 particle size of the polymer after the pulverization process may be 2 μm-10 μm.

[0140] In some embodiments, the polymer powder has a moisture content of less than or equal to 3%.

[0141] As an example, the test of the moisture content of polymer powder can refer to: "GB / T 2914-2008 Plastics / Determination of volatile matter (including water) of vinyl chloride homopolymer and copolymer resins" Method A / Oven method, sample size 5g.

[0142] In some embodiments, the moisture content of the polymer powder after the drying process may be less than or equal to 2%.

[0143] In some embodiments, the polymer has a glass transition temperature of less than or equal to 45°C.

[0144] In some embodiments, the glass transition temperature of the polymer may be less than or equal to 35° C. Thus, the polymer may exhibit a fluid state at a relatively low temperature.

[0145] As an example, the glass transition temperature test of a polymer can be referred to as follows: weigh 6±0.05 mg of sample into an aluminum crucible, shake it flat and cover it with a lid, and use a measuring instrument Netzsch DSC 3500Sirius for testing; nitrogen atmosphere, purge gas rate of 50 mL / min, protective gas rate of 100 mL / min; heating conditions: heating rate of 10°C / min, temperature range of (-70)°C-200°C.

[0146] The glass transition temperature is the temperature at which a polymer changes from a highly elastic state to a glassy state. It refers to the transition temperature of an amorphous polymer (including the non-crystalline part of a crystalline polymer) from a glassy state to a highly elastic state or from the latter to the former. It is the lowest temperature at which the macromolecular segments of an amorphous polymer can move freely, and is usually represented by Tg. Above the glass transition temperature, the polymer exhibits elasticity and a certain degree of fluidity; below the glass transition temperature, the polymer exhibits brittleness. The glass transition temperature can be measured by methods commonly used in the art, for example, it can be tested by differential scanning calorimetry with reference to GB / T19466.2.

[0147] In the third aspect of the present application, the present application proposes the use of the polymer prepared by the aforementioned method as a binder. Therefore, when the polymer is used as a binder, it has all the characteristics and advantages of the aforementioned polymer, which will not be repeated here.

[0148] In some embodiments, the aforementioned polymer may be used as a binder on the surface of the base film in the separator.

[0149] In a fourth aspect of the present application, the present application proposes a membrane, comprising the aforementioned polymer. Thus, the membrane has all the characteristics and advantages of the aforementioned polymer, which will not be described in detail here.

[0150] In some embodiments, the separator includes a separator and a bonding layer at least located on one side of the base film, and the bonding layer may contain the aforementioned polymer.

[0151] In some embodiments, when the aforementioned polymer is coated on the surface of the base film as a binder, the polymer is non-sticky at a certain temperature to facilitate the winding and unwinding of the diaphragm, but after being wound with the positive electrode sheet and the negative electrode sheet and subjected to a cold pressing process, the polymer has a better bonding force, so that the positive electrode sheet and the negative electrode sheet are closely attached to each other with the diaphragm. By coating the aforementioned binder on the base film of the diaphragm, the bonding performance between the electrode sheet and the binder can be improved, and the opening problem of the pre-cold pressing process of the battery cell can be improved, thereby improving the hardness of the electrode assembly and the cycle performance of the battery.

[0152] The present application has no particular limitation on the type of the diaphragm, and any porous structure diaphragm with good chemical stability and mechanical stability can be selected.

[0153] In some embodiments, the material of the base film includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The diaphragm can be a single-layer film or a multi-layer composite film. When the diaphragm is a multi-layer composite film, the materials of each layer can be the same or different.

[0154] In the fifth aspect of the present application, the present application proposes a battery, comprising the aforementioned separator. Therefore, the battery has all the features and advantages of the aforementioned separator, which will not be described in detail here.

[0155] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes of the battery from short-circuiting, while allowing ions to pass through.

[0156] [Positive electrode]

[0157] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector.

[0158] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0159] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one side 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.).

[0160] In some embodiments, when the battery is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art.

[0161] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 、LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn1 / 3 O 2 (Also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (Also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (Also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and its modified compounds, etc. Examples of lithium-containing phosphates with olivine structure may include but are not limited to lithium iron phosphate (such as LiFePO 4 (also referred to as LFP), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), at least one of a composite material of lithium manganese phosphate and carbon, a composite material of lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0162] The battery will be accompanied by Li deintercalation and consumption during the charge and discharge process, and the molar content of Li is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after the charge and discharge cycle.

[0163] In some embodiments, when the battery is a sodium ion battery, the positive electrode active material may be a positive electrode active material for a sodium ion battery known in the art.

[0164] As an example, the positive electrode active material may include at least one of the following materials: sodium transition metal oxides, polyanion compounds, and Prussian blue sodium compounds and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0165] 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 may satisfy Na x MO 2 , wherein M includes at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu, and 0<x≤1.

[0166] In some embodiments, the polyanionic compound may be a compound having sodium ions, transition metal ions and tetrahedral (YO 4 ) n- A class of compounds with anionic units. Among them, 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; n represents (YO 4 ) n- valence state.

[0167] In some embodiments, the polyanionic compound may also be a compound having sodium ions, transition metal ions, tetrahedral (YO 4 ) n- A class of compounds of anion units and halogen anions. 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 represents (YO 4 ) n- The halogen may include at least one of F, Cl, and Br.

[0168] In some embodiments, the polyanionic compound may also be a compound having sodium ions, tetrahedral (YO 4 ) n- Anion unit, polyhedral unit (ZO y ) m+ and an optional halogen anion. M 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 represents (YO 4 )n- valence state, Z represents a transition metal, and m represents (ZO y ) m+ The halogen may include at least one of F, Cl, and Br.

[0169] As an example, the polyanionic compound may satisfy the chemical formula NaFePO 4 、Na 3 V 2 (PO 4 ) 3 (Sodium vanadium phosphate, referred to as NVP), Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), NaM'PO 4 F (M' includes at least one of V, Fe, Mn and Ni) and Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y At least one of (0≤y≤1).

[0170] In some embodiments, the Prussian blue compound may be a compound having sodium ions, transition metal ions and cyanide ions (CN - The transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.

[0171] As an example, a Prussian blue-like compound may satisfy the chemical formula Na a Me b Me' c (CN) 6 , wherein Me and Me' each independently include at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0172] The battery will be accompanied by Na deintercalation and consumption during the charge and discharge process, and the molar content of Na is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Na is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Na will change after the charge and discharge cycle.

[0173] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0174] In some embodiments, the positive electrode active material layer may further optionally include a binder.

[0175] As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0176] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent.

[0177] As an 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.

[0178] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0179] [Negative electrode]

[0180] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0181] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two facing surfaces of the negative electrode current collector.

[0182] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, 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 side 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.).

[0183] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, 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. Silicon-based materials include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials include at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0184] In some embodiments, the negative electrode active material layer may further include a binder. The binder includes 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).

[0185] In some embodiments, the negative electrode active material layer may further include a conductive agent, which includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0186] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0187] In some embodiments, 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.

[0188] [Electrolytes]

[0189] 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. For example, the electrolyte can be liquid, gel or all-solid.

[0190] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0191] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0192] In some embodiments, the solvent includes 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, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0193] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0194] In some embodiments, 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.

[0195] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0196] In some embodiments, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the 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.

[0197] The present application has no particular limitation on the shape of the battery, which may be cylindrical, square or any other shape. Figure 5 The battery cell 5 is a square structure as an example.

[0198] In some embodiments, reference Figure 6, the outer packaging may include a shell 51 and a top cover assembly 53. Among them, 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 top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the diaphragm 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 battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0199] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0200] Figure 7 4 is an example of a battery module. Figure 7 In the battery module 4, the plurality of battery cells 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 battery cells 5 may be fixed by fasteners.

[0201] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0202] In some embodiments, 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.

[0203] Figure 8 and Fig. 9 1 is a battery pack 1 as an example. Figure 8 and Fig. 9 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0204] In the sixth aspect of the present application, the present application proposes an electrical device, comprising the aforementioned battery. Therefore, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here.

[0205] The battery, battery module, or battery pack can be used as a power source for an electrical device or as an energy storage unit for an electrical device. 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, satellites, energy storage systems, etc.

[0206] As an electrical device, a battery, a battery module or a battery pack can be selected according to its usage requirements.

[0207] Fig.10 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the battery, a battery pack or a battery module can be used.

[0208] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0209] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0210] Example 1

[0211] emulsion synthesis

[0212] The monomers include: 65wt% of n-butyl acrylate, 5wt% of trimethylolpropane triacrylate, 2wt% of acrylic acid, 3wt% of 2-hydroxyethyl acrylate, 20wt% of acrylonitrile, and 5wt% of acrylamide; the initiator is ammonium persulfate; and the emulsifier is sodium dodecyl sulfate. The mass ratio of the monomers, the initiator, and the emulsifier is 100:1:1.

[0213] Add all the emulsifiers, 30% of the total weight of the monomers, and 30% of the total weight of the initiators into the reactor, add water and stir at a speed of 30 rpm. After stirring at room temperature for 1 hour, heat to 60°C within 1 hour. Keep the stirring speed at 30 rpm, and add the remaining monomers and initiators to the reactor at a uniform speed within 3 hours. After the addition is completed, keep warm for 4 hours, adjust the pH to 5-8, and obtain a polymer emulsion. The viscosity of the polymer emulsion at 25°C is 1500mPa.s, the weight ratio of water to other components in the polymer emulsion is 50:50, and the solid content of the polymer emulsion is 50%.

[0214] Centrifugal spray drying

[0215] The aforementioned polymer emulsion was transferred to a centrifugal spray buffer stirring tank at a speed of 60 rpm. After stirring for 2 hours, the batching was completed. The spray dryer was turned on, and the air inlet temperature was set to 200°C, the air outlet temperature to 80°C, and the atomizer speed to 15000 rpm (the diameter of the atomizing disk was 180 mm, corresponding to a linear speed of 141 m / s). After stabilization, the feed pump was turned on at a feed rate of 2000 kg / h. The slurry was dried in a centrifugal spray dryer to obtain a polymer powder.

[0216] Example 2

[0217] Example 2 is consistent with Example 1, except that the polymer powder in Example 1 is conveyed to the silo of the air flow mill, the air flow mill is turned on, the pulverizing gas pressure is adjusted to 5 bar, the classifying wheel linear speed is 38.6 m / S (classifying wheel diameter 315, rotation speed 3000 rpm), and the material is collected through a dust collector to obtain a pulverized polymer.

[0218] Example 3

[0219] The difference between Example 3 and Example 1 is that the monomers in Example 3 include: 40wt% of methyl methacrylate, 40wt% of lauryl methacrylate, 3wt% of acrylic acid, 2wt% of 2-hydroxyethyl acrylate, 5wt% of trimethylolpropane triacrylate, and 20wt% of acrylonitrile, and the viscosity of the polymer emulsion at 25°C is 100mPa·s.

[0220] Example 4

[0221] The difference between Example 4 and Example 1 is that the monomers in Example 4 include: 60wt% of n-butyl acrylate, 5wt% of trimethylolpropane triacrylate, 2wt% of acrylic acid, 8wt% of 2-hydroxyethyl acrylate, and 25wt% of acrylonitrile, and the viscosity of the polymer emulsion at 25°C is 1000mPa·s.

[0222] Example 5

[0223] The difference between Example 5 and Example 1 is that the monomers in Example 5 include: 60wt% of n-butyl acrylate, 5wt% of trimethylolpropane triacrylate, 2wt% of acrylic acid, 8wt% of 2-hydroxyethyl acrylate, 15wt% of acrylonitrile, and 10wt% of acrylamide, and the viscosity of the polymer emulsion at 25°C is 2000mPa·s.

[0224] Example 6

[0225] The difference between Example 6 and Example 1 is that in Example 6, the weight ratio of water to other components in the polymer emulsion is 80:20, and the solid content of the polymer emulsion is 20%.

[0226] Example 7

[0227] The difference between Example 7 and Example 1 is that in Example 7, 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%.

[0228] Example 8

[0229] The difference between Example 8 and Example 1 is that in Example 8, the weight ratio of water to other components in the polymer emulsion is 40:60, and the solid content of the polymer emulsion is 60%.

[0230] Comparative Example 1

[0231] The difference between Comparative Example 1 and Example 1 is that the monomers in Comparative Example 1 include: 55 wt % of ethyl acrylate, 5 wt % of trimethylolpropane triacrylate, 40 wt % of acrylonitrile, and the viscosity of the polymer emulsion at 25° C. is 80 mPa·s.

[0232] Comparative Example 2

[0233] The difference between Comparative Example 2 and Example 1 is that the monomers in Comparative Example 2 include: 55wt% ethyl acrylate, 5wt% trimethylolpropane triacrylate, 20wt% acrylonitrile, 20wt% acrylamide, and the viscosity of the polymer emulsion at 25°C is 2100mPa·s.

[0234] Comparative Example 3

[0235] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the ratio of water to other components is 82:18, and the solid content of the polymer emulsion is 18%.

[0236] Comparative Example 4

[0237] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 4, the ratio of water to other components is 39:61, and the solid content of the polymer emulsion is 61%.

[0238] The polymers in Examples 1-8 and Comparative Examples 1-4 were placed on a separator and assembled into a battery, as follows:

[0239] Preparation of diaphragm

[0240] A commercially available PE microporous film with a thickness of 7 μm and an average pore size of 80 nm (from Zhuogao Electronic Technology Co., Ltd.) was used as the base film. The polymer prepared as above was stirred and mixed evenly in deionized water to obtain a slurry (solid content of 20%). The slurry was sprayed on both surfaces of the substrate and dried to remove the solvent. The coating density of the coating composition on the substrate was 1.5 g / m 2 , and obtain the diaphragm.

[0241] Preparation of positive electrode

[0242] Polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), conductive agent carbon black, and N-methylpyrrolidone (NMP) were mixed in a mass ratio of 1.2:58.38:0.42:40, and then stirred and mixed to prepare a positive electrode slurry. 2 The loading amount is evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed and cut to obtain the positive electrode sheet.

[0243] Preparation of negative electrode

[0244] Artificial graphite, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were added into deionized water in a mass ratio of 96.2:1.0:1.6:1.2, and the mixture was stirred and mixed to prepare negative electrode slurry. 2 The loading amount is coated on the negative electrode current collector copper foil, and then dried, cold pressed and cut to obtain the negative electrode sheet.

[0245] Preparation of electrolyte

[0246] At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF 6 Dissolved in the above mixed solvent to obtain an electrolyte solution, wherein LiPF 6 The concentration is 1 mol / L.

[0247] Preparation of batteries

[0248] The positive electrode sheets, separators and negative electrode sheets are stacked and wound in order, and cold-pressed (during which the separators and the electrode sheets are bonded) to obtain a battery cell; the battery cell is placed in an outer package, and the prepared electrolyte is added, and after packaging, standing, formation, aging and other processes, a secondary battery is obtained.

[0249] The polymers, separators and batteries in Examples 1-8 and Comparative Examples 1-4 were tested as follows. The test results are shown in Table 1:

[0250] Test method:

[0251] 1. Viscosity of polymer emulsion: tested using a rotary Brookfield viscometer, specifically, using a 62# rotor at 25°C.

[0252] 2. Solid content of polymer emulsion: The solid content was tested using a halogen moisture meter (Mettler HE 53) with a sample size of 1 g and a temperature of 120°C.

[0253] 3. Glass transition temperature Tg test of polymer

[0254] Weigh 6±0.05 mg of sample into an Al crucible, shake it flat and cover it with a lid, and use the measuring instrument Netzsch DSC3500Sirius for testing; nitrogen atmosphere, purge gas rate is 50 mL / min, and protective gas rate is 100 mL / min; heating conditions: heating rate is 10℃ / min, and the temperature range is -70~200℃.

[0255] 4. Particle size test of polymer

[0256] Use a laser particle size analyzer (Malvern 3000, MasterSizer3000) for testing, and use a helium-neon red light source as the main light source. Take a clean small beaker and add 1g of the sample to be tested, add a drop of surfactant, add 20ml of deionized water, and ultrasonicate at 53KHz / 120W for 5min to ensure that the sample is completely dispersed. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the ultrasonicated solution to be tested to make it evenly dispersed, put it into the sample pool as required, and start measuring the particle size. The measurement results can be read from the instrument.

[0257] 5. Moisture content of polymer powder: refer to "GB / T 2914-2008 Plastics / Determination of volatile matter (including water) of vinyl chloride homopolymer and copolymer resin" method A / oven method, sample size is 5g.

[0258] 6. Diaphragm wetted length:

[0259] The diaphragm was cut into samples with a width of 5 mm and a length of 100 mm. The two ends of the sample were fixed and placed horizontally. 0.5 mg of electrolyte was dropped in the center of the sample. After 1 minute, a photo was taken and the length of the electrolyte diffusion was measured to obtain the wetting length of the diaphragm. In order to ensure the accuracy of the test results, 10 samples were taken for testing, and the test results were obtained by calculating the average value. The electrolyte can be prepared as follows: ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a mass ratio of 30:50:20 to obtain an organic solvent, and fully dried LiPF 6 Dissolve in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0260] 7. Cyclic performance of the battery: At 25°C, the prepared battery was charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left for 5 minutes, and then discharged at 1 / 3C to 2.0V. The resulting discharge capacity was recorded as the initial capacity C. 0 Repeat the above steps for the same battery and record the discharge capacity C of the battery after the nth cycle. n , then the battery capacity retention rate P after each cycle n =C n / C 0 ×100%, using the battery capacity retention rate P at 500 times 500 Characterize the cycle performance.

[0261] Table 1

[0262]

[0263] As can be seen from Table 1, the viscosity of the polymer emulsion in Comparative Example 1 is too low, the glass transition temperature of the obtained polymer is too low, the electrolyte resistance is poor, and the bonding stability of the bonding coating formed by the polymer on the surface of the base film is poor, resulting in poor battery cycle performance; the viscosity of the polymer emulsion in Comparative Example 2 is too large, the Dv50 diameter of the obtained polymer is too large, the bonding coating formed by the polymer on the surface of the base film is too thick, and the electrolyte wettability of the diaphragm is poor, resulting in poor battery cycle performance; the solid content of the polymer emulsion in Comparative Example 3 is too low, the production energy consumption increases, and the water content of the obtained polymer powder is too high, the polymer is easy to agglomerate, and the coating quality of the bonding coating formed by the polymer on the surface of the base film is poor, resulting in poor bonding stability of the bonding coating and poor battery cycle performance; the solid content of the polymer emulsion in Comparative Example 4 is too high, the Dv50 diameter of the obtained polymer is too large, the bonding coating formed by the polymer on the surface of the base film is too thick, and the electrolyte wettability of the diaphragm is poor, resulting in poor battery cycle performance.

[0264] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a polymer, characterized in that: include: 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; Allowing the mixture to undergo a polymerization reaction to obtain a polymer emulsion, wherein the viscosity of the polymer emulsion at 25° C. is 100 mPa·s-2000 mPa·s, and the solid content of the polymer emulsion is 20%-60%; The polymer emulsion is granulated to obtain the polymer.

2. The method according to claim 1, characterized in that The mixing of the polymer monomer, the initiator and the emulsifier comprises: mixing the emulsifier with water to obtain a premix; The premix is ​​kept at a first temperature, and the polymer monomer and the initiator are added dropwise into the premix, and stirred to obtain the mixture; Optionally, 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 according to claim 2, characterized in that The first temperature is 25°C-95°C.

4. The method according to claim 2 or 3, characterized in that: The stirring process satisfies at least one of the following conditions: The stirring time is 10min-360min; The rotation speed of the stirring process is 10 rpm-100 rpm.

5. The method according to any one of claims 1 to 4, characterized in that: The step of causing the mixture to undergo a polymerization reaction comprises: The mixture is subjected to a heat preservation treatment to obtain the polymer emulsion.

6. The method according to claim 5, characterized in that The heat preservation treatment satisfies at least one of the following conditions: The heat preservation treatment time is 10min-480min; The temperature of the heat preservation treatment is 45°C-95°C.

7. The method according to any one of claims 1 to 6, characterized in that: The granulation process includes a spray drying process.

8. The method according to claim 7, characterized in that The spray drying process includes at least one of centrifugal spray drying, air flow spray drying, and pressure spray drying.

9. The method according to claim 8, characterized in that The centrifugal spray drying satisfies at least one of the following conditions: The inlet air temperature of the centrifugal spray drying is 60°C-280°C; The outlet air temperature of the centrifugal spray drying is 40°C-100°C; The linear speed of the atomizer of the centrifugal spray drying is 100m / s-500m / s.

10. The method according to claim 8, characterized in that The airflow spray drying includes at least one of two-fluid spray drying, three-fluid spray drying, and four-fluid spray drying.

11. The method according to claim 10, characterized in that The two-fluid spray drying satisfies at least one of the following conditions: The air pressure of the two-fluid spray drying is 0.1MPa-5MPa; The hydraulic pressure of the two-fluid spray drying is 0.1 MPa-100 MPa.

12. The method according to claim 10, characterized in that The three-fluid spray drying satisfies at least one of the following conditions: The first gas pressure of the three-fluid spray drying is 0.1MPa-5MPa; The second gas pressure of the three-fluid spray drying is 0.1MPa-5MPa; The hydraulic pressure of the three-fluid spray drying is 0.05 MPa-50 MPa.

13. The method according to any one of claims 1 to 12, characterized in that: The initiator satisfies at least one of the following conditions: The persulfate initiator includes at least one of potassium persulfate and ammonium persulfate; The acyl peroxide initiator comprises: at least one of benzoyl peroxide and dioctanoyl peroxide; The azo initiator includes at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

14. The method according to any one of claims 1 to 13, characterized in that: The acrylic acid ester monomers include 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 trimethylamineethyl methacrylate.

15. The method according to any one of claims 1 to 14, characterized in that: The polymer monomer further includes at least one of acrylic acid, methacrylic acid, crotonic acid, heptenoic acid, acrylamide, N-hydroxymethyl acrylamide and N-butoxymethyl acrylamide, acrylonitrile and methacrylonitrile.

16. The method according to any one of claims 1 to 15, characterized in that: The anionic emulsifier includes at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, sodium laurate, sodium stearate, and sodium palmitoleate.

17. The method according to any one of claims 1 to 16, characterized in that: Further including: The polymer is dried.

18. The method according to any one of claims 1 to 17, characterized in that: Further including: The polymer is subjected to a pulverization treatment.

19. The method according to claim 18, characterized in that The pulverizing process includes at least one of air flow milling, mechanical milling, sand milling and ball milling.

20. The method according to claim 19, characterized in that The classification linear speed of the air flow mill is 10m / s-80m / s.

21. The method according to claim 19, characterized in that The pulverizing part of the mechanical mill includes a rotor and a stator, and the pulverizing part satisfies at least one of the following conditions: (1) There is a gap between the rotor and the stator, and the width of the gap is 50 μm-5000 μm; (2) The rotor is a conical structure composed of multiple groups of ceramic modules, the ceramic modules are toothed blade groups, and the angle between the side line and the bottom line of the rotor is 65°-80°; (3) The stator is conical, and a serrated ceramic lining is embedded on the outer surface of the stator. The angle between the side line and the bottom line of the stator is 65°-80°.

22. The method according to claim 19, characterized in that The grinding media of the sand mill includes zirconium oxide beads, and the particle size of the zirconium oxide beads is 0.1 mm-3 mm.

23. A polymer, characterized in that The polymer is prepared by the method according to any one of claims 1 to 22.

24. The polymer according to claim 23, characterized in that The Dv50 particle size of the polymer is 2 μm-50 μm.

25. The polymer according to claim 23 or 24, characterized in that The water content of the polymer powder is less than or equal to 3%.

26. The polymer according to any one of claims 23 to 25, characterized in that The polymer has a glass transition temperature of less than or equal to 45°C.

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

28. A diaphragm, characterized in that: The invention comprises a polymer prepared by the method described in any one of claims 1 to 22, or a polymer described in any one of claims 23 to 26.

29. A battery, characterized in that: Comprising the diaphragm of claim 28.

30. An electrical device, characterized in that: Comprising the battery of claim 29.

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