Polymer coated separator containing secondary aggregates, method of manufacturing the same, and battery

Abstract

The present invention discloses a polymer-coated separator comprising secondary aggregates, a method for manufacturing the same, and a battery. The polymer-coated separator comprises a separator substrate and a polymer coating layer coated on at least one surface of the separator substrate, wherein the polymer coating layer comprises a plurality of randomly distributed spray coating points, and the spray coating points comprise a plurality of polymer secondary aggregates formed by the aggregation of polymer primary particles; wherein any spray coating point within the polymer coating layer satisfies 25 ≤ A / B ≤ 40000 and 100 ≤ C / A ≤ 106, where A represents the projected area of ​​the polymer secondary aggregates on the separator substrate; B represents the projected area of ​​the polymer primary particles on the separator substrate; and C represents the projected area of ​​the spray coating point on the separator substrate. By controlling the size of the polymer secondary aggregates and controlling the size distribution of the secondary aggregates within the spray coating points, the present invention obtains a coated separator having high adhesion, high ion permeability, high liquid absorption and liquid retention, and a low decomposition rate.

Description

Technology Field

[0001] The present invention relates to the field of battery separator technology, and in particular to a polymer-coated separator comprising a secondary aggregate, a method for manufacturing the same, and a battery. Background Technology

[0002] With the rapid increase in sales of hybrid vehicles over the past few years, the demand for hybrid lithium-ion batteries has risen significantly. Data indicates that as the demand industry for lithium-ion batteries develops, the market is expected to maintain a high growth rate in the future. As demand for lithium-ion batteries increases, market requirements for battery performance are becoming increasingly stringent, leading to higher demands for lithium-ion battery separators.

[0003] Conventional lithium-ion batteries have almost no adhesion between the separator and the electrode plates, causing the battery to easily detach during charging and discharging, thereby shortening the battery's cycle life. Considering this problem, existing treatment methods involve coating one or both sides of the separator with a polymer coating layer that possesses adhesive properties; the polymer used can be PVDF or PMMA. However, while these conventional polymer coating layers improve adhesion between the separator and the electrode plates, most alter the pore structure of the separator, increasing internal battery resistance and reducing the charging and discharging speed. Therefore, it is very difficult to strike a balance between the adhesiveness and permeability of the polymer coating layer and to obtain a separator that combines both. means of solving the problem

[0004] Taking this into consideration, the present invention provides a polymer-coated separator comprising a secondary aggregate having high adhesion, high permeability, high liquid absorption and liquid retention, a method for manufacturing the same, and a battery.

[0005] To achieve the above objective, a first aspect of the present invention provides a polymer-coated separator comprising secondary aggregates, wherein the separator substrate and a polymer coating layer coated on at least one surface of the separator substrate, the polymer coating layer comprises a plurality of randomly distributed spray coating points, and the spray coating points comprise a plurality of polymer secondary aggregates formed by the aggregation of polymer primary particles;

[0006] Any spray coating point within the polymer coating layer is 25≤A / B≤40000, 100≤C / A≤10 6 Satisfying, and here,

[0007] A represents the projected area of ​​polymer secondary aggregates within spray coating points on the membrane substrate;

[0008] B represents the projected area of ​​the polymer primary particles within the spray coating point on the separator substrate;

[0009] C represents the projected area of ​​the spray coating point on the separator substrate;

[0010] The effective adhesion area share of the polymer coating layer, n×∑A / S, satisfies 4%≤n×∑A / S≤50%, where,

[0011] S represents the surface area of ​​the separator substrate;

[0012] ∑A represents the sum of the projected areas of all polymer secondary aggregates within the spray coating point on the separator substrate;

[0013] n represents the number of spray coating points within the area S.

[0014] According to any embodiment of the first aspect of the present invention, 25≤A / B≤10000, 2500≤C / A≤5×10 5 And;

[0015] 6%≤n×∑A / S≤30%.

[0016] According to any embodiment of the first aspect of the present invention, the thickness of the polymer coating layer is 0.5 μm to 10 μm.

[0017] According to any embodiment of the first aspect of the present invention, the adhesion strength between the polymer-coated separator and the ternary anode is ≥ 1 N / m, and the adhesion strength between the polymer-coated separator and the graphite cathode is ≥ 0.5 N / m; and / or

[0018] The ionic conductivity of the polymer-coated separator is 80% to 110% of the ionic conductivity of the separator substrate; and / or

[0019] The liquid absorption rate of the polymer-coated separator is ≥70% and the liquid retention rate is ≥70%; and / or

[0020] The decomposition rate of the polymer-coated separator is ≤ 5%.

[0021] According to any embodiment of the first aspect of the present invention, the polymer coating layer is,

[0022] 80 to 100 parts by mass of a polymer containing secondary aggregates;

[0023] 2 to 20 parts by mass of adhesive; and

[0024] It contains 0.01 to 3 parts by mass of a dispersant.

[0025] According to any embodiment of the first aspect of the present invention, the polymer comprising the secondary aggregate comprises at least one of polyvinylidene fluoride homopolymer (PVDF), polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), polyvinylidene fluoride-methyl methacrylate copolymer (PVDF-PMMA), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-acrylic acid copolymer, polymethyl methacrylate (PMMA), polyethylene (PE), and acrylate polymer.

[0026] According to any embodiment of the first aspect of the present invention, the adhesive comprises at least one of carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, and acrylonitrile multicomponent copolymer.

[0027] According to any embodiment of the first aspect of the present invention, the dispersant comprises at least one of an ethylene-acrylic acid copolymer, an ethylene-vinyl acetate copolymer, an acrylic acid-polyurethane, and a polyethylene glycol.

[0028] According to any embodiment of the first aspect of the present invention, the separator substrate is selected from at least one of a polyethylene film, a polypropylene film, a polyimide film, a polyvinylidene fluoride film, a polyvinylidene fluoride-hexafluoropropylene film, a polyamide film, and a polyethylene terephthalate film.

[0029] According to any embodiment of the first aspect of the present invention, the thickness of the separator substrate is 3 μm to 25 μm, and the porosity is 20% to 80%.

[0030] A second aspect of the present invention provides a method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate, wherein,

[0031] Step S01: uniformly mixing a dispersant and water, adding a polymer in portions 'a', wherein the mass of the polymer added each time is 1 / a of the total amount and a≥2, and after adding the polymer each time, stirring slowly first, stirring rapidly, and stirring slowly again, continuing this process until all the polymer has been added; optionally performing a polishing treatment, and finally adding an adhesive, mixing uniformly, and filtering to obtain a polymer slurry;

[0032] Step S02: A step of obtaining a polymer coating layer by coating a polymer slurry on at least one surface of a separator substrate using a rotary spray coating method, wherein, in the rotary spray coating parameters, the coating speed is 100 m / min to 300 m / min, the spray coating slurry flow rate is 1500 mL / min to 15000 mL / min, the spray coating rotation speed is 5000 rpm to 15000 rpm, the number of teeth of the spray coating turntable is 200 to 600, and the distance between the turntable and the membrane surface is 20 cm to 50 cm;

[0033] Step S03: Includes the step of obtaining a polymer-coated separation membrane containing secondary aggregates by drying the separation membrane substrate and the polymer coating layer.

[0034] According to any embodiment of the second aspect of the present invention, step S01 is,

[0035] Step S011: A step of obtaining a first mixed solution by uniformly mixing water and a dispersant;

[0036] Step S012: A step of adding a polymer to a first mixed solution in portions a, wherein the amount of polymer added each time is 1 / a of the total amount, and after each addition, first performing a first dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, then performing a second dispersion step with a stirring speed of 1000 rpm to 2000 rpm and a stirring time of 30 min to 180 min, and finally performing a third dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, proceeding in this manner until all of the polymer is added to obtain a second mixed solution;

[0037] Step S013: Includes the step of adding an adhesive to the second mixed solution and stirring uniformly, then filtering through a filter of 40 mesh to 300 mesh to obtain a polymer slurry.

[0038] According to any embodiment of the second aspect of the present invention, the particle size D10 of the polymer slurry is 1 μm to 4 μm, and D90 is 6 μm to 20 μm.

[0039] According to any embodiment of the second aspect of the present invention, the polymer coating amount is 0.05 g / m² 2 ~ 1.5g / m 2 am.

[0040] According to any embodiment of the second aspect of the present invention, the drying treatment temperature of step S03 is 50℃ to 90℃.

[0041] A third aspect of the present invention provides a battery, which comprises a polymer-coated separator comprising a secondary aggregate provided in the first aspect of the present invention or a polymer-coated separator comprising a secondary aggregate produced by the manufacturing method provided in the second aspect of the present invention. Effects of the invention

[0042] The polymer coating separation membrane containing secondary aggregates provided in the present invention obtains a coating separation membrane having high adhesion, high ion permeability, high liquid absorption and liquid retention, and a low decomposition rate by controlling the aggregation state of the polymer secondary aggregates and the distribution of the secondary aggregates within the spray coating points.

[0043] Additional aspects and advantages of the present invention will be presented in part below, some of which will become apparent from the description below or will be understood through the practice of the invention. Brief explanation of the drawing

[0044] The drawings are intended to provide further understanding of the present invention and constitute part of the specification and are used to interpret the present invention together with the specific embodiments below, but are not intended to limit the present invention. In the drawings, Figure 1 is a scanning electron microscope image of the PVDF coating layer of a polymer-coated separator according to the present invention, observed at 200x magnification. Figure 2 is a scanning electron microscope image of the PVDF coating layer of a polymer-coated separator according to the present invention observed at 1,000x magnification. Figure 3 is a scanning electron microscope image of the PVDF coating layer of a polymer-coated separator according to the present invention observed at 10,000x magnification. Figure 4 is a schematic diagram of the turntable of a high-speed rotary spray coating machine. Figure 5 is a process flow diagram of a method for manufacturing a polymer-coated separation membrane containing secondary aggregates. Specific details for implementing the invention

[0045] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the attached drawings. It should be understood that the specific embodiments described herein are intended only to explain and interpret the present invention and are not intended to limit the present invention.

[0046] A first aspect of the present invention provides a polymer-coated separator comprising secondary aggregates, wherein the separator substrate and a polymer coating layer coated on at least one surface of the separator substrate, the polymer coating layer comprises a plurality of randomly distributed spray coating points, and the spray coating points comprise a plurality of polymer secondary aggregates formed by the aggregation of polymer primary particles;

[0047] Any spray coating point within the polymer coating layer is 25≤A / B≤40000, 100≤C / A≤10 6 Satisfying, and here,

[0048] A represents the projected area of ​​polymer secondary aggregates within spray coating points on the membrane substrate;

[0049] B represents the projected area of ​​the polymer primary particles within the spray coating point on the separator substrate;

[0050] C represents the projected area of ​​the spray coating point on the separator substrate;

[0051] The effective adhesion area share of the polymer coating layer, n×∑A / S, satisfies 4%≤n×∑A / S≤50%, where,

[0052] S represents the surface area of ​​the separator substrate;

[0053] ∑A represents the sum of the projected areas of all polymer secondary aggregates within the spray coating point on the separator substrate;

[0054] n represents the number of spray coating points within the area S.

[0055] To explain in detail, it is as follows.

[0056] The separator substrate may be a substrate without a coating layer or a substrate coated with an inorganic particle layer, and is not particularly limited.

[0057] In an embodiment of the present invention, the type of the separator substrate is not particularly limited and can be selected according to actual needs; preferably, the separator substrate may be selected from one or more of a polyethylene membrane, a polypropylene membrane, a polyimide membrane, a polyvinylidene fluoride membrane, a polyvinylidene fluoride-hexafluoropropylene membrane, a polyamide membrane, and a polyethylene terephthalate membrane.

[0058] In an embodiment of the present invention, the type of inorganic particle is not particularly limited and can be selected according to actual needs; preferably, the inorganic particle may be selected from one or more of silicon dioxide (SiO2), aluminum oxide (Al2O3), magnesium oxide (MgO), zirconium oxide (ZrO2), titanium oxide (TiO2), calcium oxide (CaO), boehmite (AlOOH), aluminum nitride (AlN), boron nitride (BN), barium sulfate (BaSO4), calcium fluoride (CaF2), and barium fluoride (BaF2).

[0059] The thickness of the above-mentioned separator substrate may be 3 μm to 25 μm, preferably 5 μm to 16 μm.

[0060] The porosity of the above-mentioned membrane substrate may be 20% to 80%, preferably 30% to 50%.

[0061] Any spray coating point in the polymer coating layer of the present invention is 25≤A / B≤40000, 100≤C / A≤10 6 Satisfying the above, where A represents the projected area of ​​polymer secondary aggregates within the spray coating point on the membrane substrate; B represents the projected area of ​​polymer primary particles within the spray coating point on the membrane substrate; and C represents the projected area of ​​the spray coating point on the membrane substrate;

[0062] The effective adhesion area share of the polymer coating layer n×∑A / S satisfies 4%≤n×∑A / S≤50%, where ∑A represents the sum of the projected areas of all polymer secondary aggregates within any spray coating point in S on the separator substrate; n represents the number of spray coating points in S; and S represents the surface area of ​​the separator substrate.

[0063] The shape of the secondary aggregate and spray coating point is not specifically limited.

[0064] 1. A / B represents the aggregation state of primary particles within the polymer secondary aggregates, and if A / B > 40000, the polymer secondary aggregates are too large, the thickness of the polymer coating layer is uneven, the coating layer is easily detached and powder is lost, affecting the local ion permeability of the separation membrane; if A / B < 25, the polymer secondary aggregates are too small, the adhesion strength of the polymer coating layer is weak, and the liquid absorption and liquid retention of the separation membrane are low.

[0065] Here, A represents the projected area of ​​the polymer secondary aggregate in the polymer coating layer, and the test method is as follows. A specific spray coating point is randomly selected, a photograph of the spray coating point at 200x magnification is taken using a scanning electron microscope, and the edge range of the polymer secondary aggregate is marked using software (e.g., image processing software such as Image J), ​​and the area of ​​this range is the projected area of ​​the polymer secondary aggregate in the polymer coating layer. The method for marking the edge range of the secondary aggregate is as follows. A line is drawn starting from a specific point on the edge of the secondary aggregate and wrapping around the edge of the secondary aggregate, wherein the wrapping angle of all line segments must be < 180° (the internal angle between each line segment and the previous line segment < 180°), and if the wrapping angle of a line segment is > 180°, the connection between the line and the starting point is broken, and the line segment wraps around a closed region, i.e., the range, and the area is the projected area of ​​the secondary aggregate.

[0066] In some embodiments, the range of A is 0.785 μm 2 ~ 314μm 2 am.

[0067] B represents the projected area of ​​the polymer primary particles in the polymer coating layer, and the test method is as follows. A specific spray coating point is randomly selected, and a photograph of the spray coating point at a magnification of 10,000 is taken using a scanning electron microscope. The range of the polymer primary particles (circular) can be marked using software (e.g., image processing software such as Image J), ​​and the area of ​​this range is the projected area of ​​the polymer primary particles in the polymer coating layer.

[0068] In some embodiments, the range of B is 7.85×10 -3 μm 2 ~ 0.785μm 2 am.

[0069] The range of A / B is 25≤A / B≤40000, for example 100 ~ 2500, 100 ~ 3600, 100 ~ 6000, 100 ~ 10000, 100 ~ 40000 or 200 ~ 1600, 200 ~ 3600, 200 ~ 6000, 200 ~ 40000 or 250 ~ 6000, 250 ~ 8000, 250 ~ 10000, 250 ~ 40000, etc.

[0070] 2. C / A represents the distribution of polymer secondary aggregates within the spray coating point; if C / A < 100, the polymer secondary aggregates within the spray coating point are too large and few in number, the thickness of the polymer coating layer is non-uniform, the coating layer detaches easily, and powder is lost; if C / A > 10 6 In this case, there are too few effective polymer aggregates within the spray coating point, the adhesion performance of the coating layer is low, liquid absorption and liquid retention are low, the exposed area of ​​the separation membrane substrate within the spray coating point is small, and the ion penetration performance is low.

[0071] Here, C represents the projected area of ​​the spray coating point in the polymer coating layer, and the test method is as follows. A specific spray coating point is randomly selected, and a photograph of the spray coating point at 200x magnification is taken using a scanning electron microscope, and the range of the spray coating point can be marked using software (e.g., image processing software such as Image J), ​​and the area of ​​this range is the projected area of ​​the spray coating point in the polymer coating layer.

[0072] It should be noted that A, B, and C select the same spray coating point during testing.

[0073] In some embodiments, the range of C is 7.85×10 -3 mm 2 ~ 0.785mm 2 It is between.

[0074] The definition of A is as stated above.

[0075] The range of C / A is 100≤C / A≤10 6 , for example, 100 ~ 160000, 600 ~ 200000, 600 ~ 300000, 800 ~ 300000, etc.

[0076] 3. n×∑A / S represents the occupancy rate of the effective adhesive area of ​​the polymer coating layer, and when n×∑A / S < 4%, the effective adhesive area is small and the adhesive strength is low; when n×∑A / S > 50%, the effective adhesive area is large, the exposed substrate area is small, the membrane permeability is low, and the ion penetration performance is low.

[0077] Here, S represents the area of ​​the substrate and n represents the number of spray coating points within the area of ​​S, and the test method is as follows. A finished separator is placed under a static CCD lens (e.g., High Level GP-300C High-Definition Electron Measurement Microscope) and a photograph is taken in a 3x magnified field of view, and image processing software is used to calculate the area S of the photograph and the number of spray coating points n within the photograph.

[0078] ∑A selects an arbitrary spray coating point within the S area (preferably a point where the spray coating point D50 is 300 to 600 μm), tests the projected area of ​​each secondary aggregate according to the test method of A described above, and then sums them up.

[0079] The range of n×∑A / S is, for example, 10 to 40%, 10 to 30%, 10 to 20%, and 10 to 15%.

[0080] In an embodiment of the present invention, the thickness of the polymer coating layer is 0.5 μm to 10 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm… … 8 μm, 9 μm, 10 μm. The thickness of the polymer coating layer is controlled within the range of 0.5 μm to 10 μm, and if the thickness is too thin, the adhesion performance is low; if the thickness is too thick, the thickness of the polymer coating layer is non-uniform, the coating layer is easily detached and powder is lost, and the ion penetration performance is low.

[0081] In an embodiment of the present invention, the adhesion strength between the polymer-coated separator and the ternary anode is ≥ 1.0 N / m, and for example, the adhesion strength between the polymer-coated layer and the ternary anode plate is 1 N / m… … 4 N / m, 4.2 N / m, 4.5 N / m, 4.6 N / m, 4.8 N / m, 5 N / m, … …

[0082] In an embodiment of the present invention, the adhesion strength between the polymer-coated separator and the graphite cathode plate is ≥ 0.5 N / m, and for example, the adhesion strength between the polymer-coated separator and the graphite cathode plate is 0.5 N / m… … 4 N / m, 4.2 N / m, 4.5 N / m, 4.6 N / m, 4.8 N / m, 5 N / m, … …

[0083] The adhesion strength between the polymer-coated separator and the battery electrode plate can be tested by methods known in the art. As a specific example, a test method for adhesion strength may be as follows. A polymer coating layer of the battery separator and a ternary anode or a graphite cathode are laminated and subjected to heat compression using a heat press, and then the 180-degree peel strength is tested as the adhesion strength using a tensile tester, wherein the speed of the tensile tester is 50 mm / min; wherein the heat compression treatment conditions are preferably a heat compression temperature of 90°C, a heat compression pressure of 6.5 MPa, and a heat compression time of 60 s.

[0084] In an embodiment of the present invention, the ionic conductivity of the polymer-coated separator is 80% to 110% of the ionic conductivity of the separator substrate, for example, 81%, 82%, 85%, 90%… … 110%.

[0085] The ionic conductivity of the separator can be tested by methods known in the art. As a specific example, a test method for ionic conductivity may be as follows. The ionic conductivity of the separator is given by the formula σ s = It can be calculated as, and σ s is the conductivity of the separator, Rs is the resistance of the separator, d is the thickness of the separator, and S is the effective area of ​​the separator;

[0086] In an embodiment of the present invention, the liquid absorption rate of the polymer-coated separator is ≥70%, e.g., 70%, 80%, 90%, 95%, and the liquid retention rate is ≥70%, e.g., 70%, 80%, 90%, 95%;

[0087] The liquid absorption rate and liquid retention rate of the separator can be tested using methods known in the art. As a specific example, the test method for the liquid absorption rate and liquid retention rate may be as follows. Refer to QB / T 2303.11-2008 "Part 11 of Battery Pulp Layer Paper: Measurement of Liquid Absorption Rate" to perform the measurement. A 50mm × 50mm separator sample is cut and weighed as m0, then immersed in a beaker containing electrolyte, and after immersion for 1 hour, removed and suspended in the air for 3 minutes, allowing electrolyte to drip and weighing as m, then left at room temperature for 1 hour and weighed as m1. The liquid absorption rate X and liquid retention rate Y of the lithium-ion battery separator can be calculated using the following formulas.

[0088] X=

[0089] Y=

[0090] In the formula, m0 represents the mass of the membrane before immersion, m represents the mass of the membrane after immersion, and m1 represents the mass after being left at room temperature for 1 hour.

[0091] In an embodiment of the present invention, the decomposition rate of the polymer-coated separator is ≤5%, for example, 4%, 3%, 2%, or 1%.

[0092] The delamination rate primarily characterizes the loss of powder in the polymer spray coating layer. Due to the loss of powder in the separator, the adhesion of the separator deteriorates, and there is a risk of heat pressing failure. The specific test method is as follows. Take a finished polymer spray coating separator, weigh it, and record the weight as m0. Then, place the membrane in a slitting machine and run it idle. After winding, weigh it again and record the weight as m1. The delamination rate P = (m0 - m1) / m0 × 100%.

[0093] In an embodiment of the present invention, the components of the polymer coating layer comprise 80 to 100 parts by mass of polymer; 2 to 20 parts by mass of adhesive; and 0.01 to 3 parts by mass of dispersant.

[0094] In an embodiment of the present invention, the polymer comprising a secondary aggregate comprises at least one of polyvinylidene fluoride homopolymer (PVDF), polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), polyvinylidene fluoride-methyl methacrylate copolymer (PVDF-PMMA), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-acrylic acid copolymer, polymethyl methacrylate (PMMA), polyethylene (PE), and acrylate polymer.

[0095] The polymer containing the secondary aggregate of the present invention mainly refers to a solid form.

[0096] In some embodiments, the particle size range of the primary particles of the polymer is 0.1 μm to 1 μm, and the B value is controlled by selecting various types of polymer (e.g., PVDF resin).

[0097] In the embodiments of the present invention, the type of adhesive is not particularly limited and can be selected according to actual needs; preferably, the adhesive may be selected from one or more of carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, and acrylonitrile multi-component copolymer.

[0098] In the embodiments of the present invention, the type of dispersant is not particularly limited and can be selected according to actual needs; preferably, the dispersant may be selected from one or more of ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic acid-polyurethane, and polyethylene glycol.

[0099] The battery separator provided in the embodiment of the present invention can be used in various types of batteries, so the type of battery is not specifically limited and can be selected according to actual needs. Preferably, it can be used in secondary batteries, particularly secondary batteries containing a liquid electrolyte, such as lithium-ion batteries, sodium-ion batteries, etc.

[0100] A second aspect of the present invention provides a method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate, and as illustrated in FIG. 5, this,

[0101] Step S01: uniformly mixing a dispersant and water, adding a polymer in portions 'a', wherein the mass of the polymer added each time is 1 / a of the total amount and a≥2, and after adding the polymer each time, stirring slowly first, stirring rapidly, and stirring slowly again, continuing this process until all the polymer has been added; optionally performing a polishing treatment, and finally adding an adhesive, mixing uniformly, and filtering to obtain a polymer slurry;

[0102] Step S02: A polymer slurry is coated on at least one surface of a membrane substrate using a rotary spray coating method to obtain a polymer coating layer having spray coating points, wherein, in terms of rotary spray coating parameters, the coating speed is 100 m / min to 300 m / min, the spray coating slurry flow rate is 1500 mL / min to 15000 mL / min, the spray coating rotation speed is 5000 rpm to 15000 rpm, the number of teeth of the spray coating turntable is 200 to 600 (a schematic diagram of the turntable of a high-speed rotary spray coater is shown in FIG. 4), and the distance between the turntable and the membrane surface is 20 cm to 50 cm;

[0103] Step S03: Includes the step of obtaining a polymer-coated separation membrane containing secondary aggregates by drying the separation membrane substrate and the polymer coating layer.

[0104] In an embodiment of the present invention, step S01 of the manufacturing method is,

[0105] Step S011: A step of obtaining a first mixed solution by uniformly mixing water and a dispersant;

[0106] Step S012: A step of adding a polymer to a first mixed solution in portions a, wherein the amount of polymer added each time is 1 / a of the total amount, and after each addition, first performing a first dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, then performing a second dispersion step with a stirring speed of 1000 rpm to 2000 rpm and a stirring time of 30 min to 180 min, and finally performing a third dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, proceeding in this manner until all of the polymer is added to obtain a second mixed solution;

[0107] Step S013: The method further includes the step of adding an adhesive to the second mixed solution and stirring uniformly, then filtering through a filter of 40 mesh to 300 mesh (which can filter out large PVDF particles that are not dispersed).

[0108] By adding the PVDF resin in multiple stages, the PVDF resin can be better dispersed. First, slow stirring is performed to prevent scattering of the PVDF powder during the mixing process, and then rapid stirring is performed to accelerate the mixing of the PVDF in water. By controlling the number of times the PVDF resin is added, the rotation speed and time of slow and high-speed stirring, and the size of the filter, the desired PVDF slurry (secondary particle) size can be obtained, thereby controlling the A / B range.

[0109] In some embodiments, the D10 particle size of the obtained polymer slurry is 1 μm to 4 μm, and the D90 particle size is 6 μm to 20 μm (A value range control). The particle sizes D10 and D90 of the slurry can be tested using a laser particle size analyzer.

[0110] The size of C / A is controlled by adjusting the size of C by controlling the spray coating rotation speed, slurry flow rate, the number of teeth on the spray coating turntable, and the distance between the turntable and the film surface.

[0111] The size of the effective adhesive area n×∑A / S is controlled by adjusting the size of A and the flow rate of the spray coating slurry.

[0112] In some embodiments, the obtained spray coating point D10 is 100μm to 300μm, and D90 is 800μm to 1000μm.

[0113] The test method for D10 and D90 of the spray coating points may be as follows. A finished product separator is placed under a static CCD lens and a photograph is taken in a 3x magnified field of view. By using image processing software to calculate the number of spray coating points n and the size of each spray coating point within the photograph, the D10 and D90 of the spray coating points are statistically obtained.

[0114] In an embodiment of the present invention, the separation membrane substrate and the PVDF coating layer adopt a general drying treatment method.

[0115] In an embodiment of the present invention, the drying treatment temperature is 50℃ to 90℃.

[0116] According to the method provided in the second embodiment of the embodiment of the present invention, a polymer-coated separation membrane comprising a secondary aggregate according to any embodiment of the first embodiment of the present invention can be obtained. Obtaining a polymer-coated separation membrane comprising a secondary aggregate according to any embodiment of the first embodiment of the present invention is not limited to the manufacturing method provided in the second embodiment of the embodiment of the present invention.

[0117] Figures 1 to 3 show scanning electron microscope images of the PVDF coating layer of the coated membrane at various drainage levels (model SIGMA 300, acceleration voltage EHT=1kV, working distance WD=5.8–6.1mm, SE2 detector).

[0118] A third aspect of the present invention provides a battery, which comprises a polymer-coated separator comprising a secondary aggregate provided in the first aspect of the embodiment of the present invention or a polymer-coated separator comprising a secondary aggregate produced by the manufacturing method provided in the second aspect of the embodiment of the present invention.

[0119] In an embodiment of the present invention, the battery is a lithium-ion secondary battery or a sodium-ion secondary battery.

[0120] The present invention will be described below with reference to specific embodiments, but it should be noted that such embodiments are illustrative and do not limit the invention in any way.

[0121] The raw materials, reagents, methods, etc. used in the examples are all conventional raw materials, reagents, and methods in the art unless otherwise specified.

[0122] The high-speed rotary spray coating machine is the Hong Kong Far Standard DS-800-01 PCS separator spray coating machine.

[0123] Example 1: Preparation of PVDF aqueous spray coating slurry: 57 kg of water and 0.025 kg of dispersant were weighed and stirred at 500 rpm for 30 min to obtain a first mixed solution; 5 kg of PVDF-HFP resin (Dongguang Sunshine HEVER2601, with a primary particle size of 0.1 to 0.3 μm) was added to the first mixed solution in two stages, with an addition amount of 2.5 kg each time; after adding the PVDF-HFP resin each time, the mixture was first stirred slowly at a rotation speed of 300 rpm for 30 min, then stirred rapidly at a rotation speed of 1000 rpm for 60 min, and finally stirred slowly at a rotation speed of 300 rpm for 20 min, and the entire mixture was added in this manner to obtain a second mixed solution; Next, 0.25 kg of polyacrylic acid adhesive is added to the second mixed solution and stirred at 50 rpm for 30 min to obtain a third mixed solution, and finally, filtered through a 200 mesh filter to obtain a PVDF spray coating slurry, wherein the D10 of the PVDF spray coating slurry is 2.1 μm and the D90 is 7.6 μm.

[0124] Coating: A prepared PVDF spray coating slurry is poured into the loading tank of a high-speed rotary spray coater through an automatic feeding system and coated on the surface of one side of a polyethylene wet base membrane with a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 150 m / min, the number of teeth of the spray coating turntable is 360, the distance between the turntable and the membrane surface is 25 cm, the spray coating slurry flow rate is 5000 mL / min, and the spray coating rotation speed is 9000 rpm; and the coating is dried at 60°C to obtain an aqueous PVDF coated separation membrane.

[0125] The spray coating point D10 obtained after coating is 200 μm, and D90 is 800 μm.

[0126] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-1 below.

[0127] Example 2: Preparation of PVDF aqueous spray coating slurry: 57 kg of water and 0.0025 kg of dispersant were weighed and stirred at 500 rpm for 30 min to obtain a first mixed solution; 5 kg of PVDF-HFP resin (manufacturer Arkema, LBG, primary particle size is 0.15 to 0.2 μm) was added to the first mixed solution in three separate additions, with an addition amount of 1.667 kg each time; after each addition of the PVDF-HFP resin, the mixture was first stirred slowly at a rotation speed of 500 rpm for 30 min, then stirred rapidly at a rotation speed of 1500 rpm for 90 min, and finally stirred slowly at a rotation speed of 500 rpm for 30 min, thereby adding the entire amount to obtain a second mixed solution; Next, 0.25 kg of polyacrylic acid adhesive is added to the second mixed solution and stirred at 50 rpm for 30 min to obtain a third mixed solution, and finally, filtered through a 300 mesh filter to obtain a PVDF spray coating slurry, wherein the D10 of the PVDF spray coating slurry is 1.6 μm and the D90 is 7.2 μm.

[0128] Coating: A prepared PVDF spray coating slurry is poured into the loading tank of a spray coater through an automatic supply system and coated on the surface of one side of a polyethylene wet base membrane with a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, with a coating speed of 200 m / min. In the following example, rotary spray coating is performed using a dispersion disc type spray coating turntable, with 450 teeth on the spray coating dispersion disc, a distance of 25 cm between the turntable and the membrane substrate, a spray coating slurry flow rate of 7500 mL / min, a spray coating rotation speed of 9000 rpm, and dried at 85°C to obtain an aqueous PVDF coated membrane.

[0129] The spray coating point D10 obtained after coating is 150 μm, and D90 is 850 μm.

[0130] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-1 below.

[0131] Example 3: Preparation of PMMA aqueous spray coating slurry: 82.75 kg of water and 0.009 kg of dispersant were weighed and stirred at 300 rpm for 30 min to obtain a first mixed solution; 15 kg of PMMA powder (manufacturer Indile, primary particle size is 0.2 to 0.5 μm) was added to the first mixed solution in three portions, with an addition amount of 5 kg each time; after each addition of PMMA powder, the mixture was first stirred slowly at a rotation speed of 400 rpm for 30 min, then stirred rapidly at a rotation speed of 1200 rpm for 80 min, and finally stirred slowly at a rotation speed of 500 rpm for 30 min, thereby adding the entire amount to obtain a second mixed solution; Next, 2.25 kg of polyacrylic acid adhesive (adhesive solid content 40%) is added to the second mixed solution and stirred at 20 rpm for 30 min to obtain a third mixed solution, and finally, filtered through a 150 mesh filter to obtain a PMMA aqueous spray coating slurry, wherein the D10 of the PMMA spray coating slurry is 1.7 μm and the D90 is 14.1 μm.

[0132] Coating: A prepared spray coating slurry is poured into the loading tank of a spray coater through an automatic supply system and coated on the surface of one side of a polyethylene wet base membrane with a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 150 m / min, the number of teeth on the spray coating dispersion disc is 360, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 4000 mL / min, the spray coating rotation speed is 9000 rpm, and the membrane is dried at 80°C to obtain an aqueous PMMA coated membrane.

[0133] The spray coating point D10 obtained after coating is 210 μm, and D90 is 800 μm.

[0134] The PMMA secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-1 below.

[0135] Example 4: Preparation of PVDF-PMMA copolymer aqueous spray coating slurry: 45 kg of water and 0.015 kg of dispersant were weighed and stirred at 500 rpm for 30 min to obtain a first mixed solution; 5 kg of PVDF-PMMA powder (primary particle size is 0.2 to 0.4 μm) was added to the first mixed solution in two stages, with an amount of 2.5 kg added each time; after adding the PMMA powder each time, the mixture was first stirred slowly at a rotation speed of 600 rpm for 30 min, then stirred rapidly at a rotation speed of 1800 rpm for 100 min, and finally stirred slowly at a rotation speed of 600 rpm for 30 min, and the entire mixture was added in this manner to obtain a second mixed solution; Next, 1.25 kg of polyacrylic acid adhesive (adhesive solid content 40%) is added to the second mixed solution and stirred at 20 rpm for 30 min to obtain a third mixed solution, and finally, filtered through a 100 mesh filter to obtain a PVDF-PMMA aqueous spray coating slurry, wherein the D10 of the spray coating slurry is 2.3 μm and the D90 is 12.5 μm.

[0136] Coating: A prepared spray coating slurry is poured into the loading tank of a spray coater through an automatic supply system and coated on the surface of a 7+2 ceramic coating film using a rotary spray coating method, wherein 7 represents a polyethylene wet base film with a thickness of 7 μm and a porosity of 40%, and 2 represents a 2 μm ceramic coating layer, the coating speed is 100 m / min, the number of teeth on the spray coating dispersion disc is 360, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 2200 mL / min, the spray coating rotation speed is 8500 rpm, and the coating is dried at 65°C to obtain an aqueous PVDF-PMMA coated membrane.

[0137] The spray coating point D10 obtained after coating is 230 μm, and D90 is 820 μm.

[0138] The PVDF-PMMA coating membrane secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, membrane performance, and parameters are shown in Table 1-1 below.

[0139] Example 5: Preparation of PVDF-PMMA copolymer aqueous spray coating slurry: Same as Example 4.

[0140] Coating: A prepared spray coating slurry is poured into the loading tank of a spray coater through an automatic supply system and coated on both sides of a 7+2 ceramic coating film using a rotary spray coating method, wherein 7 represents a polyethylene wet base film with a thickness of 7 μm and a porosity of 40%, and 2 represents a 2 μm ceramic coating layer, the coating speed is 100 m / min, the number of teeth on the spray coating dispersion disc is 360, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 2200 mL / min, the spray coating rotation speed is 8500 rpm, and the coating is dried at 65°C to obtain an aqueous PVDF-PMMA coated membrane.

[0141] The spray coating point D10 obtained after coating is 230 μm, and D90 is 820 μm.

[0142] The PVDF-PMMA coating membrane secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, membrane performance, and parameters are shown in Table 1-1 below.

[0143] Comparative Example 1: Preparation of PVDF aqueous spray coating slurry: 52 kg of water and 0.3 kg of dispersant are weighed and stirred for 30 min to obtain a first mixed solution; 20 kg of PVDF-HFP emulsion (primary particle size is 0.15 to 0.2 μm) is added to the first mixed solution, the solid content of the emulsion is 30%, and the mixture is uniformly mixed at a rotational speed of 200 rpm for 30 min to obtain a second mixed solution; 0.5 kg of polyacrylic acid adhesive is added to the second mixed solution and stirred for 30 min to obtain a PVDF spray coating slurry, wherein the D10 of the PVDF spray coating slurry is 0.15 μm and the D90 is 0.6 μm.

[0144] Coating: A prepared PVDF spray coating slurry is poured into the loading tank of a spray coater through an automatic feeding system and coated on the surface of one side of a polyethylene wet base membrane with a thickness of 12 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 100 m / min, the number of teeth on the spray coating dispersion disc is 450, the distance between the turntable and the membrane substrate is 30 cm, the spray coating slurry flow rate is 3200 mL / min, the spray coating rotation speed is 7200 rpm, and the membrane is dried at 85°C to obtain an aqueous PVDF coated membrane.

[0145] The spray coating point D10 obtained after coating is 100 μm, and D90 is 600 μm.

[0146] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-2 below.

[0147] Comparative Example 2: Preparation of PVDF aqueous spray coating slurry: 57 kg of water and 0.0025 kg of dispersant are weighed and stirred for 30 min to obtain a first mixed solution; 5 kg of PVDF resin powder (primary particle size is 0.15 to 0.2 μm) is added to the first mixed solution and first stirred slowly at a rotation speed of 200 rpm for 50 min, then stirred rapidly at a rotation speed of 600 rpm for 60 min, and finally stirred at a rotation speed of 200 rpm for 30 min, then uniformly mixed to obtain a second mixed solution, and then 0.25 kg of polyacrylic acid adhesive is added to the second mixed solution and stirred at 50 rpm for 30 min to obtain a third mixed solution without filtration, wherein the D10 of the PVDF spray coating slurry is 3.8 μm and the D90 is 35 μm.

[0148] Coating: A prepared PVDF spray coating slurry is poured into the loading tank of a spray coater through an automatic feeding system and coated on the surface of one side of a polyethylene wet base membrane with a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 150 m / min, the number of teeth on the spray coating dispersion disc is 450, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 5000 mL / min, and the spray coating rotation speed is 12000 rpm.

[0149] The spray coating point D10 is 80 μm, and D90 is 600 μm.

[0150] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-2 below.

[0151] Comparative Example 3: Preparation of PVDF aqueous spray coating slurry: Same as Example 1.

[0152] Coating: A prepared PVDF spray coating slurry is coated on the surface of one side of a polyethylene wet base membrane having a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 200 m / min, the number of teeth on the spray coating dispersion disk is 800, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 9000 mL / min, the spray coating rotation speed is 17000 rpm, and the membrane is dried at 85°C to obtain a polymer coated membrane containing secondary aggregates.

[0153] The spray coating point D10 obtained after coating is 50 μm, and D90 is 300 μm.

[0154] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-2 below.

[0155] Comparative Example 4: Preparation of PVDF aqueous spray coating slurry: 57 kg of water and 0.0025 kg of dispersant were weighed and stirred at 500 rpm for 30 min to obtain a first mixed solution; 5 kg of PVDF-HFP resin (primary particle diameter is 0.15 to 0.2 μm) was added to the first mixed solution in five portions, with an addition amount of 1 kg each time; after each addition of PVDF-HFP resin, the mixture was stirred slowly at a rotation speed of 500 rpm for 30 min, then stirred rapidly at a rotation speed of 2500 rpm for 100 min, and finally stirred at a rotation speed of 500 rpm for 30 min; the above operation was repeated until the PVDF-HFP resin was completely uniformly mixed to obtain a second mixed solution; Next, 0.25 kg of polyacrylic acid adhesive is added to the second mixed solution and stirred at 50 rpm for 30 min to obtain a third mixed solution, and finally, filtered through a 300 mesh filter to obtain a PVDF spray coating slurry, wherein the D10 of the PVDF spray coating slurry is 1.2 μm and the D90 is 5.6 μm.

[0156] Coating: A prepared PVDF spray coating slurry is coated onto the surface of one side of a polyethylene wet base membrane having a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 200 m / min, the number of teeth on the spray coating dispersion disk is 280, the distance between the turntable and the membrane substrate is 25 cm, the spray coating slurry flow rate is 6000 mL / min, and the spray coating rotation speed is 4000 rpm. The membrane is dried at 85°C to obtain a polymer coated membrane containing secondary aggregates, wherein the spray coating point D10 is 350 μm and D90 is 1500 μm.

[0157] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-2 below.

[0158] Comparative Example 5: Preparation of PVDF aqueous spray coating slurry: Same as Comparative Example 2.

[0159] Coating: Same as Comparative Example 3.

[0160] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-2 below.

[0161] Comparative Example 6: Preparation of PVDF aqueous spray coating slurry: Same as Comparative Example 4.

[0162] Coating: A prepared PVDF spray coating slurry is coated onto the surface of one side of a polyethylene wet base membrane having a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 300 m / min, the number of teeth on the spray coating dispersion disk is 180, the distance between the turntable and the membrane substrate is 15 cm, the spray coating slurry flow rate is 16000 mL / min, and the spray coating rotation speed is 4500 rpm. The membrane is dried at 85°C to obtain a polymer coated membrane containing secondary aggregates, wherein the spray coating point D10 is 450 μm and D90 is 2000 μm.

[0163] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-3 below.

[0164] Comparative Example 7: Preparation of PVDF aqueous spray coating slurry: Same as Comparative Example 2.

[0165] Coating: A prepared PVDF spray coating slurry is coated onto the surface of one side of a polyethylene wet base membrane having a thickness of 9 μm and a porosity of 50% using a rotary spray coating method, wherein the coating speed is 150 m / min, the number of teeth on the spray coating dispersion disk is 300, the distance between the turntable and the membrane substrate is 15 cm, the spray coating slurry flow rate is 1000 mL / min, and the spray coating rotation speed is 6000 rpm. The membrane is dried at 80°C to obtain a polymer coated membrane containing secondary aggregates, wherein the spray coating point D10 is 220 μm and D90 is 1000 μm.

[0166] The PVDF secondary aggregate accumulation state A / B, spray coating point accumulation state C / A, effective adhesion area, and membrane performance parameters are shown in Table 1-3 below.

[0167] Test section

[0168] Related performance tests were performed on the PVDF coating layers and battery separators of Examples 1 to 5 and Comparative Examples 1 to 7, and the test results are shown in Tables 1-1, 1-2, and 1-3 below.

[0169] Table 1-1

[0170]

[0171] Table 1-2

[0172]

[0173] Table 1-3

[0174]

[0175] From the results of the examples and comparative examples, in the case of Examples 1 to 5, A / B, C / A, and n×∑A / S are all within the given range, and the adhesion performance, ion conductivity, liquid absorption / liquid retention rate, and powder loss are effectively balanced to achieve optimal effects; in the case of Comparative Example 1, using emulsion-type PVDF-HFP without a secondary aggregate structure, A / B is too small and C / A is too large, and while the adhesion performance is high, the ion conductivity, liquid absorption, and liquid retention are low; in the case of Comparative Example 2, the powder is added and dispersed all at once during the slurry preparation process, and the stirring speed is too slow, resulting in low dispersion performance of the powder in water; and because the final slurry is not filtered, the PVDF particle size in the slurry is too large and the distribution range is wide, A / B is too large and C / A is normal, both adhesion performance and ion permeability performance are low, the defraction rate increases significantly, and the coating layer powder loss is severe; In the case of Comparative Example 3, the secondary aggregate is normal, an 800-tooth dispersion disk is used, and the spray coating rotation speed is 17,000 rpm; thus, the spray coating point is too small, A / B is normal, C / A is too small, the accumulation of the spray coating point is high, and there is no distinct change in adhesive strength, while the ionic conductivity decreases significantly and the decomposition rate increases; in the case of Comparative Example 4, PVDF powder is added in five stages during the slurring process and stirred at ultra-high speed; the PVDF secondary aggregate has a rotation speed that is too low, a small number of teeth on the turntable, a large spray coating point, A / B is too small, C / A is too large, both adhesion and ionic conductivity decrease, and liquid absorption and liquid retention rates decrease significantly; in the case of Comparative Example 5, the secondary aggregate is too large, the spray coating point is too small, A / B is too large, C / A is too small, both adhesion and ionic conductivity decrease, and the decomposition rate increases significantly;In the case of Comparative Example 6, the spray coating flow rate is too high, the number of turntable teeth is too low, the coating amount is high, the spray coating point is too large, so n×∑A / S is too large, and the ion conductivity is significantly reduced; in the case of Comparative Example 7, the spray coating flow rate is too low, the slurry particle size is too large, the coating amount is low, so n×∑A / S is too small, and the adhesion strength between the coating layer and the anode and cathode plates is significantly reduced.

[0176] From the results of the examples and comparative examples, it can be seen that high adhesion, high ion permeability, high liquid absorption and liquid retention, and low decomposition rate can be achieved only when A / B, C / A, and n×∑A / S are all within the given range. Although embodiments of the present invention have been illustrated and described above, it should be understood that the aforementioned embodiments are illustrative and should not be understood as limiting the present invention, and those skilled in the art may change, modify, substitute, and alter the aforementioned embodiments within the scope of the present invention.

Claims

Claim 1 A polymer-coated separator comprising secondary aggregates, comprising: a separator substrate; and a polymer coating layer coated on at least one surface of the separator substrate, wherein the polymer coating layer comprises a plurality of randomly distributed spray coating points, and the spray coating points comprise a plurality of polymer secondary aggregates formed by the aggregation of polymer primary particles; and any spray coating point within the polymer coating layer has 25≤A / B≤40000 and 100≤C / A≤10 6 A polymer-coated separation membrane comprising secondary aggregates, characterized by satisfying the following: A represents the projected area of ​​polymer secondary aggregates within spray coating points on the separation membrane substrate; B represents the projected area of ​​polymer primary particles within spray coating points on the separation membrane substrate; C represents the projected area of ​​spray coating points on the separation membrane substrate; the effective adhesion area share of the polymer coating layer n × ∑A / S satisfies 4% ≤ n × ∑A / S ≤ 50%, S represents the surface area of ​​the separation membrane substrate; ∑A represents the sum of the projected areas of all polymer secondary aggregates within spray coating points on the separation membrane substrate; and n represents the number of spray coating points within the area of ​​S. Claim 2 In paragraph 1, 25≤A / B≤10000, 2500≤C / A≤5×10 5 A polymer-coated separator comprising a secondary aggregate characterized by 6%≤n×∑A / S≤30%. Claim 3 A polymer-coated separator comprising a secondary aggregate according to claim 1, characterized in that the adhesion strength between the polymer-coated separator and the ternary anode is ≥1 N / m and the adhesion strength between the polymer-coated separator and the graphite cathode is ≥0.5 N / m; and / or the ionic conductivity of the polymer-coated separator is 80% to 110% of the ionic conductivity of the separator substrate; and / or the liquid absorption rate of the polymer-coated separator for the electrolyte is ≥70% and the liquid retention rate is ≥70%; and / or the powder removing rate of the polymer-coated separator is ≤5%. Claim 4 A polymer coating separation membrane comprising secondary aggregates, characterized in that, in any one of claims 1 to 3, the polymer coating layer comprises 80 to 100 parts by mass of a polymer comprising secondary aggregates; 2 to 20 parts by mass of an adhesive; and 0.01 to 3 parts by mass of a dispersant. Claim 5 A polymer-coated separator comprising a secondary aggregate according to claim 4, wherein the polymer comprising the secondary aggregate comprises at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride-methyl methacrylate copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-acrylic acid copolymer, polymethyl methacrylate, polyethylene, and acrylate polymer; and / or, the adhesive comprises at least one of carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, and acrylonitrile multi-component copolymer; and / or, the dispersant comprises at least one of ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylic acid-polyurethane, and polyethylene glycol. Claim 6 A polymer-coated separation membrane comprising a secondary aggregate, characterized in that, in any one of claims 1 to 3, the thickness of the separation membrane substrate is 3 μm to 25 μm and the porosity is 20% to 80%; and / or the thickness of the polymer coating layer is 0.5 μm to 10 μm. Claim 7 A method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate according to claim 1, comprising: Step S01: uniformly mixing a dispersant and water, then adding a polymer in portions 'a', wherein the mass of the polymer added each time is 1 / a of the total amount and 'a' ≥ 2, and after adding the polymer each time, first stirring slowly, then stirring rapidly, then stirring slowly again, and proceeding in this manner until all the polymer is added, and finally adding an adhesive, mixing uniformly, and filtering to obtain a polymer slurry; and Step S02: coating the polymer slurry on at least one surface of a separation membrane substrate by a rotary spray coating method to obtain a polymer coating layer, wherein, in the rotary spray coating parameters, the coating speed is 100 m / min to 300 m / min, the spray coating slurry flow rate is 1500 mL / min to 15000 mL / min, the spray coating rotation speed is 5000 rpm to 15000 rpm, the number of teeth of the spray coating turntable is 200 to 600, and the distance between the turntable and the membrane surface is The method comprises a step of 20 cm to 50 cm; and Step S03: a step of drying the membrane substrate and the polymer coating layer to obtain a polymer-coated membrane containing secondary aggregates, wherein Step S01 comprises: Step S011: a step of uniformly mixing water and a dispersant to obtain a first mixed solution; and Step S012: a step of adding a polymer to the first mixed solution in portions 'a', wherein the amount of polymer added each time is 1 / a of the total amount, and after each addition, first performing a first dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, then performing a second dispersion step with a stirring speed of 1000 rpm to 2000 rpm and a stirring time of 30 min to 180 min, and finally performing a third dispersion step with a stirring speed of 100 rpm to 600 rpm and a stirring time of 10 min to 50 min, proceeding in this manner until all of the polymer is added to obtain a second mixed solution;Step S013: A method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate, characterized by including the step of adding an adhesive to a second mixed solution and stirring uniformly, and then filtering through a filter of 40 mesh to 300 mesh to obtain a polymer slurry.; Claim 8 A method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate, characterized in that, in claim 7, the particle size D10 of the polymer slurry is 1 μm to 4 μm and D90 is 6 μm to 20 μm. Claim 9 In claim 7, the polymer coating amount is 0.05 g / m² 2 ~ 1.5g / m 2 A method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate characterized by being. Claim 10 A method for manufacturing a polymer-coated separation membrane comprising a secondary aggregate according to claim 7, characterized in that, in step S01, all of the polymer is added and then polished, and finally, an adhesive is added and uniformly mixed, and then filtered to obtain a polymer slurry. Claim 11 A battery characterized by comprising a polymer-coated separator containing a secondary aggregate according to any one of claims 1 to 3.

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