Separator and manufacturing method thereof, secondary battery and power consumption device

Abstract

The present invention provides a separator and manufacturing method, a secondary battery (5), and a power consumption device. The separator includes a substrate and a coating disposed on at least one side of the substrate. The coating includes first particles and second particles, the first particles being organic particles, and the second particles having a pore structure. The separator has good heat resistance and ion transport properties, thereby improving the thermal safety performance and cycle performance of a battery using the separator.

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and more particularly to a separator and its manufacturing method, a secondary battery, and a power consuming device. [Background technology]

[0002] In recent years, with the development of battery technology, batteries have been endowed with features such as high energy density, good cycle performance and safety performance, and are therefore widely used in power tools such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, hammer drills, concrete vibrators, electric planers, etc., as well as electric transportation tools such as electric motorcycles, electric passenger cars, electric vans, light commercial vehicles, electric trucks, electric buses, electric leisure boats, electric commercial short-distance and deep-sea vessels, and electric manned aircraft.

[0003] With the widespread use and application of batteries in many fields, the demand for their thermal safety and cycle performance has increased accordingly. However, in related art, the thermal safety performance of batteries deteriorates during the temperature rise process, and their cycle performance also deteriorates. Therefore, it is necessary to improve the thermal safety and cycle performance of batteries. Summary of the Invention

[0004] The purpose of the present application is to provide a separator and a manufacturing method thereof, a secondary battery, and a power consumption device, which have characteristics such as good heat resistance and ion transport properties, thereby improving the thermal safety performance and cycle performance of a battery using this separator.

[0005] A first aspect of the present application provides a separator, comprising: a substrate; and a coating disposed on at least one side of the substrate, wherein the coating comprises first particles and second particles, the first particles being organic particles, and the second particles having a pore structure.

[0006] In the separator of the present application, the first particles in the coating are organic particles, which have relatively excellent heat resistance. When the separator shrinks due to heat, the first particles, the second particles, and / or the first and second particles in the coating may come into contact with each other as the substrate shrinks, and this can provide a force on the substrate in the direction opposite to the shrinkage direction, thereby reducing the degree of separator shrinkage and reducing the risk of short-circuiting between the positive and negative electrodes in the battery, thereby improving the thermal safety performance of the battery. In addition, the second particles have a porous structure that can store electrolyte and improve the separator's liquid absorption and retention rates, and the pores can act as ion channels to transport ions, allowing the battery to achieve both good heat resistance and better cycle performance.

[0007] In any embodiment of the present application, the average pore size of the second particles is from 0.1 nm to 10 nm, and optionally from 0.4 nm to 5 nm.

[0008] In any embodiment of the present application, the porosity of the second particles is 10% to 60%, and optionally 30% to 50%.

[0009] In any embodiment of the present application, the average particle size of the second particles is 2 μm or less, and optionally 0.1 μm to 1 μm. The average particle size of the second particles within this appropriate range contributes to the electrolyte permeating the separator and improving the cycle performance of the battery, as well as to the contact between the particles. Furthermore, when the separator is subjected to heat, the second particles quickly provide a force in the opposite direction to the heat-receiving direction of the separator, thereby reducing the degree of shrinkage when the separator is subjected to heat and improving the thermal safety performance of the battery.

[0010] In any embodiment of the present application, the specific surface area of the second particles is 100 m 2 / g or more, and selectively 500m 2 / g~2000m 2By setting the specific surface area of the second particles within the appropriate range, the contact area between the second particles and the electrolyte can be increased, which further contributes to improving the infiltration effect and liquid retention effect of the electrolyte into the separator.

[0011] In any embodiment of the present application, the ratio of the weight ratio A of the first particles to the weight ratio B of the second particles, based on the weight of the coating, is 1

[0012] In any embodiment of the present application, the ratio of the weight ratio A of the first particles to the weight ratio B of the second particles satisfies 5≦A / B≦15, based on the weight of the coating.

[0013] In any embodiment of the present application, the weight ratio B of the second particles in the coating is 20% or less, and optionally 0.1% to 15%.

[0014] In any embodiment of the present application, the second particles comprise one or more of inorganic particles and metal-organic framework materials; In any embodiment of the present application, the inorganic particles include one or more of titanium oxide, zirconium oxide, barium oxide, magnesium oxide, barium sulfate, magnesium aluminum silicate, zirconium titanate, barium titanate.

[0015] In any embodiment of the present application, the metal-organic framework material comprises one or more of IRMOFs, ZIFs, MILs, PCNs, CPLs, UiOs.

[0016] In any embodiment of the present application, the second particles have a through-hole structure.

[0017] ​In any embodiment of the application, the first particles include one or more of silicone particles, melamine formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles, and optionally the first particles include silicone particles.

[0018] In any embodiment of the present application, the first particles comprise silicone particles, and the silicone particles comprise a first polymer, the first polymer comprising first structural units, second structural units, and third structural units; The first structural unit has the structure shown in formula (I): [ka] In formula (I), R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, optionally R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; R2 comprises one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C1-C20 hydroxyalkyl group, optionally R2 comprises one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, a C1-C12 hydroxyalkyl group; The second structural unit is as shown in formula (II): [ka] In formula (II), R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, optionally R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; The third structural unit is as shown in formula (III): [ka] In formula (III), R4 to R 11 each independently represents a substituted or unsubstituted C1-C10 alkyl group, or contains one or more of the structural units shown in formula (III-1), where at least one of R4 to R 11 is a structural unit shown in formula (III-1),

Chemical formula

[0019] In any embodiment of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, 70 ≤ a ≤ 90, and optionally, 75 ≤ a ≤ 85, and / or, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is denoted as b%, 0 < b ≤ 16, and optionally, 5 ≤ b ≤ 15, and / or Based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is denoted as c%, 2 ≤ c ≤ 15, and optionally, 5 ≤ c ≤ 10.

[0020] In any embodiment of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, the molar content of the second structural unit is denoted as b%, the molar content of the third structural unit is denoted as c%, and the silicone particles satisfy conditions (1) to (3), (1) The condition that 4≦a / b≦15; (2) the condition that 5≦a / c≦14; (3) One or more of the following conditions are satisfied: a:b:c is (13-16):(1-3):(3-4).

[0021] In any embodiment of the present application, the first particles comprise silicone particles, and the silicone particles comprise a second polymer, the second polymer comprising structural units shown in formula (a): [ka] In formula (a), R 14 and R 15 each independently comprise one or more of a substituted or unsubstituted C1-C10 alkyl group, hydroxy or amino group, and optionally R 14 and R 15 each independently contain one or more of a substituted or unsubstituted C1-C6 alkyl group, hydroxy, or amino group.

[0022] In any embodiment of the present application, the number average molecular weight of the silicone particles is 35,000 to 70,000, and optionally 40,000 to 55,000.

[0023] In any embodiment of the present application, the moisture content of the silicone particles may be 2500 μg / g or less, and optionally 700 μg / g to 2000 μg / g, based on the mass of the silicone particles.

[0024] In any embodiment of the present application, the silicone particles have an average particle size of 3 μm or less.

[0025] In any embodiment of the present application, the silicone particles have an average particle size of 0.01 μm to 2 μm.

[0026] In any embodiment of the present application, the specific surface area of the silicone particles is 12.0 m 2 / g or less, and selectively 5.0m 2 / g~10.0m 2 / g.

[0027] In any embodiment of the present application, the thickness of the substrate is 16 μm or less, and optionally 3 μm to 12 μm.

[0028] In any embodiment of the present application, the porosity of the substrate is 25% or more, and optionally 30% to 45%.

[0029] In any embodiment of the present application, the separator has a longitudinal heat shrinkage rate of 2% or less at 150°C for 1 hour.

[0030] In any embodiment of the present application, the separator has a thermal shrinkage rate in the transverse direction at 150°C for 1 hour of 2% or less.

[0031] In any embodiment of the present application, the separator has an air permeability of 230 s / 100 cc or less, and optionally 160 s / 100 cc to 200 s / 100 cc.

[0032] In any embodiment of the present application, the separator has a longitudinal tensile strength of 2700 kg / cm 2 or more, and optionally 3000 kg / cm 2 ~4500kg / cm 2 is.

[0033] In any embodiment of the present application, the separator has a transverse tensile strength of 2000 kg / cm 2 or more, and optionally 2500 kg / cm 2 ~4500kg / cm 2 is.

[0034] In any embodiment of the present application, the separator has an ionic conductivity of 0.8 S / m to 1.5 S / m.

[0035] A second aspect of the present application provides a method for producing the separator of the first aspect of the present application, the method comprising: providing a substrate; Mixing organic particles as first particles and second particles having a pore structure in a solvent to prepare a coating slurry; applying the coating slurry to at least one side of the substrate to form a slurry film layer, and drying the slurry film layer to form a coating, thereby obtaining a separator.

[0036] A third aspect of the present application provides a secondary battery, the battery comprising the separator of the first aspect of the present application or comprising a separator produced by the method of the second aspect of the present application.

[0037] A fourth aspect of the present application provides a power consuming device, the power consuming device including the secondary battery of the third aspect of the present application. [Brief explanation of the drawings]

[0038] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] 1 is a schematic diagram of one embodiment of a secondary battery of the present application. [Figure 2] FIG. 2 is an exploded schematic view of an embodiment of the secondary battery of FIG. 1. [Figure 3] 1 is a schematic diagram of one embodiment of a battery module of the present application. [Figure 4] 1 is a schematic diagram of one embodiment of a battery pack of the present application. [Figure 5] FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4. [Figure 6] 1 is a schematic diagram of one embodiment of the present application including a secondary battery-powered power consuming device. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, with appropriate reference to the drawings, specific embodiments of the separator and manufacturing method thereof, secondary battery, and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and repeated description of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0040] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise specified, the numerical range "ab" is a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have already been listed in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0042] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0043] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0044] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0045] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0046] In this application, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood to denote or imply relative importance.

[0047] As used in this application, the terms "plurality" and "various" mean two or more.

[0048] Unless otherwise specified, terms used in this application have the known meanings commonly understood by those skilled in the art.

[0049] Unless otherwise specified, the numerical values of each parameter mentioned in this application can be tested using various test methods commonly used in the art, and can be measured, for example, according to the test methods given in the embodiments of this application.

[0050] Generally, a battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is placed between the positive electrode plate and the negative electrode plate and serves mainly to prevent short circuits between the positive and negative electrodes, while allowing active ions to pass freely through the separator to complete a circuit.

[0051] As batteries become more widespread and more widely used, the demands for their thermal safety and cycle performance are also increasing. Separators are a key component for improving the thermal safety and cycle performance of batteries. Currently, separators used in commercial batteries are generally polyolefin films, whose melting points are between 130°C and 160°C. When heated, these films experience significant thermal shrinkage, reducing their electrolyte penetration and the active material passage area, leading to active material accumulation on the separator surface and resulting in reduced battery cycle performance. Furthermore, dendrites can form on the separator surface and penetrate the separator, causing direct contact between the positive and negative electrodes inside the battery, resulting in an internal short circuit and further increasing battery safety risks.

[0052] In view of this, the present application provides a separator and a manufacturing method thereof, a secondary battery, and a power consumption device, and the separator has excellent heat resistance and ion transport properties, thereby improving the thermal safety performance and cycle performance of a battery using the separator.

[0053] Separator A first aspect of an embodiment of the present application provides a separator, comprising a substrate and a coating disposed on at least one side of the substrate, wherein the coating comprises first particles and second particles, the first particles being organic particles and the second particles having a pore structure.

[0054] In the separator of the present application, the first particles in the coating are organic particles, which have relatively good heat resistance. When the separator shrinks under heat, the first particles, the second particles, and / or the first and second particles in the coating may come into contact with each other due to the shrinkage of the substrate, and this can provide a force on the substrate in the direction opposite to the shrinkage direction, thereby reducing the degree of separator shrinkage, reducing the risk of short-circuiting between the positive and negative electrodes in the battery, and improving the thermal safety performance of the battery. Furthermore, the inventors discovered that when only organic particles are used in the coating, if the interparticle spacing is not sufficiently dense, the separator will experience severe thermal shrinkage. However, if the interparticle spacing is dense, the heat resistance can be improved, but the porosity of the coating will be low, resulting in fewer ion channels, which is detrimental to improving the cycle performance of the battery. After extensive research, the inventors discovered that the above problems can be effectively solved when the coating contains both first and second particles. The inventors speculated that the second particles having a pore structure can store the electrolyte and improve the liquid absorption rate and liquid retention rate of the separator, and that the pore size can act as ion channels to transport ions, thereby enabling the battery to have good heat resistance and at the same time better cycle performance.

[0055] In some embodiments of the present application, the average pore size of the second particles is 0.1 nm to 10 nm, and optionally 0.4 nm to 5 nm. The average pore size of the second particles within the above range contributes to improving the infiltration effect and liquid retention effect of the electrolyte solution in the coating, thereby improving the cycleability of the battery.

[0056] Illustratively, the average pore size of the second particles is 0.4 nm, 0.42 nm, 0.44 nm, 0.46 nm, 0.48 nm, 0.50 nm, 0.52 nm, 0.54 nm, 0.56 nm, 0.58 nm, 0.60 nm, 0.62 nm, 0.64 nm, 0.66 nm, 0.68 nm, 0.70 nm, 0.72 nm, 0.74 nm, 0.76 nm, 0.78 nm, 0.80 nm, 0.82 nm, 0.84 nm, 0.86 nm, 0.88 nm, 0.90 nm, 0.92 nm, 0.94 nm, 0.96 nm, 0.9 ... The average pore size of the second particles may be, but is not limited to, 0.4 nm to 10 nm, 0.42 nm to 9 nm, 0.50 nm to 8 nm, 0.60 nm to 7 nm, or 1 nm to 6 nm.

[0057] The average pore size has a meaning known in the art and can be measured using an instrument and a method known in the art. For example, it can be calculated by the Brunauer Emmett Teller (BET) method with reference to GB / T21650.2-2008, and the test can be performed using a Tri-Star 3020 specific surface area pore size analyzer manufactured by Micromeritics, USA.

[0058] In some embodiments of the present application, the porosity of the second particles is 10% to 60%, and optionally 30% to 50%. The porosity of the second particles within this range can improve the infiltration and retention effects of the electrolyte coating, which is beneficial for ion transport, thereby improving the cycleability of the battery and also providing the second particles with relatively high mechanical strength.

[0059] The porosity of a material, as known in the art, refers to the ratio of the pore volume within a particle to the total volume of the particle. It can be measured using instruments and methods known in the art. For example, see the national standard GB / T 24586-2009, "Measurement of Apparent Density, True Density, and Porosity of Iron Ore," and use the AccuPyc II 1340 fully automated true density analyzer from Micromeritics, USA, to obtain the porosity. Porosity = (V1 - V2) / V1 * 100%, where V1 refers to the apparent volume of the material and V2 refers to the true volume of the material. V1 can be measured using the mercury intrusion method, and V2 can be measured using the nitrogen gas adsorption method.

[0060] In some examples, the porosity of the second particles may be, but is not limited to, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a range consisting of any two of the foregoing values. Alternatively, the porosity of the second particles may be 10% to 50%, 16% to 40%, 20% to 36%, or 24% to 32%.

[0061] In some embodiments of the present application, the average particle size of the second particles is 2 μm or less. The average particle size of the second particles within this suitable range contributes to the electrolyte permeating the separator to improve the cycle performance of the battery, as well as to the contact between the particles. Furthermore, when the separator is subjected to heat, the second particles quickly provide a force opposite to the direction in which the separator is subjected to heat, thereby reducing the degree of shrinkage of the separator when subjected to heat and improving the thermal safety performance of the battery.

[0062] In the present application, the average particle size has a meaning known in the art and can be measured using known instruments and methods in the art. For example, the material or separator may be examined using a scanning electron microscope, a transmission electron microscope, or a particle size distribution analyzer to obtain an image, and a plurality of test particles (e.g., 100 or more) (e.g., first particles or second particles) may be randomly selected from the image, and the average value of the lengths of the shortest diagonals of the particles may be calculated as the average particle size.

[0063] In some other embodiments of the present application, the average particle size of the second particles may be 0.1 μm to 1 μm.

[0064] In some examples, the average particle size of the second particles is 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.80 μm, 0.85 μm, 0.9 μm, 0.95 μm, 1.0 μm, 1.05 μm, 1.1 μm, 1.15 μm, 1.25 μm, 1.25 μm, 1.35 μm, 1.45 μm, 1.55 μm, 1.65 μm, 1.75 μm, 1.85 μm, 1.95 μm, 1.95 μm, 1.15 μm, 1.25 μm, 1.35 μm, 1.45 μm, 1.55 μm, 1.65 μm, 1.75 μm, 1.85 μm, 1.9 ... The average particle size of the second particles may be, but is not limited to, 2 μm, 1.25 μm, 1.3 μm, 1.35 μm, 1.4 μm, 1.45 μm, 1.5 μm, 1.55 μm, 1.60 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.9 μm, 1.95 μm, 2.0 μm, or a range consisting of any two of the above values. Alternatively, the average particle size of the second particles may be 0.01 μm to 1.8 μm, 0.06 μm to 1.6 μm, 0.1 μm to 1.2 μm, 0.2 μm to 1 μm, or 0.4 μm to 0.8 μm.

[0065] In some embodiments of the present application, the specific surface area of the second particles is 100 m 2 / g or more, and selectively 500m 2 / g~2000m 2 By setting the specific surface area of the second particles within the appropriate range, the contact area between the second particles and the electrolyte can be increased, which further contributes to improving the infiltration effect and liquid retention effect of the electrolyte into the separator.

[0066] In this application, the specific surface area of particles has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be tested using the nitrogen gas adsorption specific surface area analysis test method in accordance with GB / T 19587-2017 and calculated using the Brunauer Emmett Teller (BET) method. Alternatively, the nitrogen gas adsorption specific surface area analysis test can be performed using a Tri-Star 3020 specific surface area pore size analyzer manufactured by Micromeritics, USA.

[0067] In some instances, the specific surface area of the second particles is 100 m 2 / g, 150m 2 / g, 200m 2 / g, 250m 2 / g, 300m 2 / g, 350m 2 / g, 400m 2 / g, 450m 2 / g, 500m 2 / g, 550m 2 / g, 600m 2 / g, 650m 2 / g, 700m 2 / g, 750m 2 / g, 800m 2 / g, 850m 2 / g, 900m 2 / g, 950m 2 / g, 1000m 2 / g, 1050m 2 / g, 1100m 2 / g, 1150m 2 / g, 1200m 2 / g, 1250m 2 / g, 1300m 2 / g, 1350m 2 / g, 1400m 2 / g, 1450m 2 / g, 1500m 2 / g, 1550m 2 / g, 1600m 2 / g, 1650m 2 / g, 1700m 2 / g, 1750m 2 / g, 1800m 2 / g, 1850m 2 / g, 1900m 2 / g, 1950m 2 / g, 2000m 2 / g or a range consisting of any two of the above values, but is not limited thereto, and optionally, 100m 2 / g~1900m 2 / g, 200m 2 / g~1600m 2 / g, 600m 2 / g~1000m 2 / g, or 700m 2 / g-900m 2 / g.

[0068] In the embodiment of the present application, the weight ratio of the first particles to the weight ratio of the second particles in the coating satisfying an appropriate relationship not only contributes to reducing the degree of shrinkage of the separator and improving the thermal safety performance of the battery, but also enables better contact between the first particles and allows the second particles to be dispersed between adjacent first particles, forming more voids between the particles, further improving the infiltration effect of the electrolyte and improving the cycle performance of the battery.

[0069] In some embodiments of the present application, the ratio of the weight ratio A of the first particles to the weight ratio B of the second particles, based on the weight of the coating, is 1.

[0070] ​In some examples, the ratio of the weight ratio A of the first particles to the weight ratio B of the second particles can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, or a range consisting of any two of the foregoing values, optionally 1 to 19, 5 to 25, 8 to 20, or 10 to 18.

[0071] In some embodiments of the present application, the weight ratio B of the second particles in the coating is 20% or less, and optionally 0.1% to 15%.

[0072] Also, in some embodiments of the present application, the coating may further include auxiliary agents such as binders, dispersants, wetting agents, etc. in addition to the first particles and the second particles.

[0073] In some embodiments of the present application, the second particles include one or more of inorganic particles and metal-organic framework materials. When inorganic particles and metal-organic framework materials (e.g., MOF materials) having porous structures are used in combination with the first particles, the separator can better improve the electrolyte wetting and retention effects.

[0074] Optionally, the inorganic particles having a pore structure may include one or more of titanium oxide, zirconium oxide, barium oxide, magnesium oxide, barium sulfate, magnesium aluminum silicate, zirconium titanate, and barium titanate.

[0075] Metal-organic frameworks (MOFs) generally refer to a class of materials that contain metal ions and organic ligands.

[0076] Optionally, the metal-organic framework material may comprise one or more of IRMOFs (Isoreticular Metal-Organic Frameworks), ZIFs (Zeolitic Imidazolate Frameworks), MILs (Metaria lsofistitute Lavoisier Frameworks), PCNs (Porous Coordination Networks), CPLs (Coordination Pillared-Layers), UiOs (University of Oslos).

[0077] Optionally, the IRMOFs include one or more of IRMOF-1, IRMOF-3, IRMOF-4, IRMOF-8, IRMOF-9, IRMOF-10, IRMOF-11, IRMOF-12, IRMOF-13, IRMOF-14, IRMOF-16, IRMOF-18, IRMOF-61, IRMOF-62.

[0078] Selectively, ZIFs include ZIF-1, ZIF-2, ZIF-4, ZIF-5, ZIF-7, ZIF-8, nZIF-8, ZIF-9, ZIF-10, ZIF-11, ZIF-12, ZIF-14, ZIF-20, ZIF-23, ZIF-60, ZIF-61, ZIF-62, ZIF-64, ZI Contains one or more of F-65, ZIF-67, ZIF-68, ZIF-69, ZIF-70, ZIF-71, ZIF-72, ZIF-73, ZIF-74, ZIF-75, ZIF-76, ZIF-77, ZIF-78, ZIF-95, ZIF-100, ZIF-268, ZIF-224.

[0079] Optionally, the MILs include one or more of MIL-53 Cr, MIL-100 Cr, MIL-101 Cr, MIL-100 Fe, MIL-177-LT, MIL-177-HT, MIL-45 Co, MIL-45 Fe, MIL-53AI, MIL-53 Sc, MIL-88 Sc, MIL-8, MIL-9, MIL-47, MIL-51, MIL-59, MIL-69, MIL-88, MIL-91, MIL-96, MIL-101, MIL-103, MIL-102, MIL-110, MIL-125.

[0080] Optionally, the PCNs include one or more of PCN-800, PCN-777, PCN-700, PCN-426, PCN-333.

[0081] Optionally, the CPLs include one or more of CPL-1, CPL-2, CPL-4, CPL-5, CPL-6, and Al-CPL.

[0082] Optionally, the UiOs include one or more of UiO-66(Ce), UiO-66(Zr), UiO-66(Hf), UiO-66(Th), UiO-66(Ti), Im-UiO-66, UiO-67, UiO-68, UiO-15, UiO-7, UiO-15, UiO-21, UiO-22, UiO-28, UiO-26, UiO-27, DBP-UiO, and UIO-66-COOH.

[0083] In some embodiments of the present application, the second particles have a through-pore structure, which can shorten the ion transport path and store a larger amount of electrolyte, thereby contributing to improving the cycle performance of the secondary battery.

[0084] As mentioned above, the first particles in the coating have relatively good heat resistance, which can provide the separator with good heat resistance and reduce its shrinkage degree; therefore, the appropriate organic particles can further improve the separator's heat resistance and provide the battery with better thermal safety performance.

[0085] In some embodiments of the present application, the first particles include one or more of silicone particles, melamine formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramid particles, polyphenylene sulfide particles, polypropylene particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles.

[0086] Alternatively, the first particles may include silicone particles, which refer to organosiloxanes whose main chains are silicon-bonded (-Si-O-Si-). Because the silicon bond is an inorganic bond, its bond energy is relatively large, endowing the silicone with high heat resistance and chemical stability. For example, silicones can be used for long periods at temperatures below 200°C. The silicone side chains may be ungrafted or may be grafted with organic groups. Grafting organic groups can impart good dispersibility to the silicone, improving the coating performance of the silicone coating and its affinity with the substrate. Dispersing silicone particles in the coating provides the separator with good heat resistance, thereby improving the thermal safety of secondary batteries. Furthermore, a structure with voids between the silicone particles can be formed, further improving the separator's electrolyte penetration and retention properties, thereby facilitating the transport of active ions in the separator. When the separator is used in a secondary battery, the cycle performance of the battery can be improved.

[0087] In some embodiments of the present application, the first particles comprise silicone particles, and the silicone particles comprise a first polymer, and the first polymer comprises a first structural unit, a second structural unit, and a third structural unit.

[0088] The first structural unit has the structure shown in formula (I): [ka] In formula (I), R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, optionally R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; R2 comprises one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C1-C20 hydroxyalkyl group, optionally R2 comprises one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, a C1-C12 hydroxyalkyl group; The second structural unit is as shown in formula (II): [ka] In formula (II), R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, optionally R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; The third structural unit is as shown in formula (III): [ka] In formula (III), R4 to R 11 each independently comprises a substituted or unsubstituted C1-C10 alkyl group or one or more structural units represented by formula (III-1), and R4 to R 11 At least one of the structural units is represented by formula (III-1), [ka] In formula (III-1), R 12 contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R 12 contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group, and R 13comprises a substituted or unsubstituted C1-C10 alkyl group, optionally R 13 includes substituted or unsubstituted C3-C10 alkyl groups.

[0089] The first structural unit can adjust the glass transition temperature of the polymer and improve the toughness and peel strength of the first polymer, contributing to good adhesive properties. The second structural unit can produce excellent swelling resistance, i.e., when the first polymer is applied to a separator, the first polymer is in contact with the electrolyte and is less likely to swell, resulting in relatively excellent swelling resistance. The polysilsesquioxane in the third structural unit can be considered a material having an organic-inorganic hybrid core-shell structure, with the inner inorganic framework as the core, i.e., the framework structure composed of Si-O-Si or Si-O bonds, and the housing composed of organic substituents (C1-C5 alkyl groups), the organic substituents being wrapped around the outside of the framework structure and connected to the Si element of the framework structure. The polysilsesquioxane core structure can endow the polymer with advantages in terms of heat resistance and mechanical performance, and its relatively low shrinkage can ensure the thermal stability of the first polymer during the long-term cycle charge-discharge process of the battery, effectively isolating the positive and negative electrodes, and thereby ensuring the thermal safety performance of the battery. Furthermore, because polysilsesquioxane has a small particle size and a large specific surface area, on a physical scale it is similar to many polymer segments, so the atoms on the polysilsesquioxane surface have relatively high reactivity, and polymers modified with polysilsesquioxane have relatively high properties such as heat resistance, flame retardancy, and oxidation resistance.

[0090] Furthermore, a synergistic effect can be exerted between the structural units in the first polymer. Specifically, the first structural unit and the third structural unit work together to exert a synergistic effect, which can improve the adhesive performance and heat resistance of the first polymer, and the first structural unit and the second structural unit work together to exert a synergistic effect, which can improve the swelling resistance of the first polymer.

[0091] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, and 70 ≦ a ≦ 90. When the molar content of the first structural unit is within the above range, the flexibility of the first polymer can be improved, thereby further enhancing the adhesiveness of the first polymer. When the first polymer is applied to a separator, the bonding strength between the first polymer and the substrate of the separator can be improved. Optionally, 75 ≦ a ≦ 85. Exemplarily, the molar content of the first structural unit may be 70%, 75%, 80%, 85%, 90%, or a range consisting of any two of the above numerical values.

[0092] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is denoted as b%, and 0 < b ≦ 16. When the molar content of the second structural unit is within the above range, the swelling resistance of the first polymer can be significantly improved. Optionally, 5 ≦ b ≦ 15. Exemplarily, the molar content of the second structural unit may be 5%, 8%, 10%, 12%, 15%, or a range consisting of any two of the above numerical values.

[0093] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is denoted as c%, and 2 ≦ c ≦ 15. When the molar content of the third structural unit is within the above range, the heat resistance of the first polymer can be guaranteed, and its occupancy rate is relatively small, which is advantageous for improving the occupancy rates of the first structural unit and the second structural unit and enhancing the adhesiveness and thermal stability of the entire first polymer. Optionally, 5 ≦ c ≦ 10. Exemplarily, the molar content of the third structural unit may be 5%, 8%, 10%, 12%, 15%, or a range consisting of any two of the above numerical values.

[0094] In the present application, the first structural unit in the first polymer imparts good adhesion to the first polymer. However, when the first polymer is used in a separator, contact with the electrolyte is unavoidable, and the swelling effect of the electrolyte reduces the adhesiveness of the first polymer to some extent. The cyano group contained in the second structural unit in the first polymer exerts a synergistic effect with the first structural unit, thereby improving both the swelling resistance and adhesive performance of the first polymer. In particular, when the present application further satisfies 4≦a / b≦15, a more sufficient synergistic effect between the first structural unit and the second structural unit can be exerted, thereby improving the adhesiveness and swelling resistance of the first polymer. For example, a / b may be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a range consisting of any two of the above values.

[0095] Furthermore, the third structural unit in the first polymer comprises a polysilsesquioxane inorganic structure and acts synergistically with the first structural unit to improve the heat resistance and adhesive performance of the entire first polymer. In particular, when the present application further satisfies 5≦a / c≦14, a more sufficient synergistic effect can be exerted between the first structural unit and the third structural unit, improving the adhesive performance and heat resistance of the first polymer. For example, a / c may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or a range consisting of any two of the above values.

[0096] In some embodiments of the present application, the degree of polymerization a of the first structural unit, the degree of polymerization b of the second structural unit, and the degree of polymerization c of the third structural unit satisfy the following ratio: a:b:c=(13-16):(1-3):(3-4). When the degrees of polymerization of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratio, the three types of structural units in the silicone particles can exhibit their respective performance advantages, and the three types of structural units can cooperate with each other to improve the adhesion, swelling resistance, and heat resistance of the polymer.

[0097] The first structural unit includes a plurality of chemical structures, and specific chemical structures of the first structural unit will be described below.

[0098] In some embodiments of the present application, R1 is selected from a hydrogen atom and / or a methyl group.

[0099] In some embodiments of the present application, R2 comprises one or more of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a dodecyl group, or an isobornyl group.

[0100] Exemplarily, the first structural unit includes one or more of the structures shown in formula (I-1) to formula (I-8), [ka]

[0101] The second structural unit includes a plurality of chemical structures, and specific chemical structures of the second structural unit will be described below.

[0102] In some embodiments of the present application, R3 is selected from a hydrogen atom or a methyl group.

[0103] Exemplarily, the second structural unit includes one or more of the structures shown in formula (II-1) to formula (II-4), [ka]

[0104] The third structural unit includes a plurality of chemical structures, and specific chemical structures of the third structural unit will be described below.

[0105] In some embodiments of the present application, R4 to R 11 are each independently selected from the structural units shown in formula (III-1), and optionally, R 12contains one or more of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or an n-pentyl group, and / or R 13 contains one or more of an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, or a 2-ethylhexyl group.

[0106] In some embodiments, R4 to R 11 is selected from the structural units shown in formula (III-1), and optionally, R 12 contains one or more of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or an n-pentyl group, and / or R 13 contains one or more of an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, or a 2-ethylhexyl group.

[0107] In the present application, the type of group in the first polymer can be measured by infrared spectroscopy. For example, the type of modifying group can be determined by examining the infrared absorption spectrum of the material and determining the characteristic peaks contained therein. Specifically, infrared spectroscopy of the material can be performed using an instrument and method known in the art, for example, an infrared spectrometer (e.g., an IS10 Fourier transform infrared spectrometer manufactured by Nicolet, USA) in accordance with GB / T 6040-2019 General Methods for Infrared Spectroscopy.

[0108] In some embodiments of the present application, the infrared spectrum of the first polymer shows a peak at 1750 cm indicating the presence of ester groups. -1 From 1735cm -1 It has a characteristic peak.

[0109] In some embodiments of the present application, the infrared spectrum of the first polymer shows a peak at 2260 cm indicating the presence of cyano groups.-1 From 2220cm -1 It has a characteristic peak.

[0110] In some embodiments of the present application, the infrared spectrum of the first polymer exhibits a peak at 1100 cm indicating the presence of a silsesquioxane Si-O-Si framework. -1 From 1120cm -1 It has a characteristic peak.

[0111] In some embodiments of the present application, the first polymer may be produced by the following method, which comprises: Step S100 of providing a first monomer, a second monomer, and a third monomer; and step S200 of mixing the first monomer, the second monomer, and the third monomer, and causing a polymerization reaction under the action of an initiator to produce a first polymer.

[0112] In the present application, a first monomer, a second monomer and a third monomer are mixed and then copolymerized, and the formed first polymer is a copolymer of the three types of monomers.

[0113] The first monomer has the structure shown in formula (IV): [ka] In formula (IV), R1 comprises a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, optionally R1 is selected from one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; R2 comprises a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C1-C20 hydroxyalkyl group, and optionally R2 is selected from one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group.

[0114] The first monomer is an acrylate compound, which when polymerized opens a carbon-carbon double bond to form a first structural unit.

[0115] Illustratively, the first monomer includes one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0116] The second monomer has the structure shown in formula (V): [ka] In formula (V), R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R3 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group.

[0117] The second monomer is an acrylonitrile-based compound, which when polymerized opens its carbon-carbon double bond to form a second structural unit.

[0118] Illustratively, the second monomer includes acrylonitrile and / or methacrylonitrile.

[0119] The third monomer shown has the structure shown in formula (VI): [ka] In formula (VI), R 30 From R 37 comprises one or more independently selected from a substituted or unsubstituted C1-C10 alkyl group or a structural unit represented by formula (VI-1), wherein R 30 From R 37 At least one of the structural units is represented by formula (VI-1), [ka] In formula (VI-1), R 12 contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R 12 contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group, R 13 comprises a substituted or unsubstituted C1-C10 alkyl group, optionally R 13 includes substituted or unsubstituted C3-C10 alkyl groups.

[0120] Illustratively, the third monomer comprises one or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacryloyloxypropylheptaisobutylpolysilsesquioxane, methacryloyloxypropylheptaoctylpolysilsesquioxane, acryloyloxypropyl cage-type polysilsesquioxane, acryloyloxypropylheptaisobutylpolysilsesquioxane, and methacryloyloxypropylheptaoctylpolysilsesquioxane.

[0121] In some embodiments of the present application, step S200 specifically includes: Step S210: adding a first monomer, a second monomer, and a third monomer to a solvent and an emulsifier and mixing them to form a mixed system; and step S220 of adding an initiator to the mixed system and causing a polymerization reaction by the action of the initiator to produce a first polymer.

[0122] In the present application, the copolymerization of multiple monomers can be carried out by emulsion polymerization, which is a more convenient polymerization method. Of course, other polymerization methods can also be used in the present application, such as solution polymerization, suspension polymerization, etc., and the process parameters used in the polymerization process can be selected from those commonly used in the art, and will not be further described here.

[0123] In some embodiments of the present application, the emulsifier comprises one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl diphenyloxide disulfonate, ethoxylated alkyl phenol ammonium sulfate.

[0124] In some embodiments of the present application, the ratio of the mass percentage content of the emulsifier to the mass percentages of the first monomer, the second monomer, and the third monomer, based on the total mass of the mixed system, is 0.1% to 5%, i.e., the amount of the emulsifier used is 0.1% to 5% of the mass of the three types of monomers. When the mass percentage content of the emulsifier is in the above range, the first monomer, the second monomer, and the third monomer may be emulsified and dispersed in a solvent to form a relatively uniform system.

[0125] In some embodiments of the present application, the initiator comprises potassium persulfate and / or ammonium persulfate.

[0126] In some embodiments of the present application, the ratio of the mass percentage content of the initiator to the mass percentage content of the first monomer, the second monomer, and the third monomer, based on the total mass of the mixed system, is 0.15% to 1%, that is, the amount of initiator used is 0.15% to 1% of the mass of the three monomers. When the mass percentage content of the initiator is in the above range, sufficient polymerization can be ensured.

[0127] In some embodiments of the present application, the solvent may include water, for example, deionized water.

[0128] As a specific example, the method includes:

[0129] Preparation of prepolymer: deionized water, emulsifier, first polymerizable monomer, second polymerizable monomer and third polymerizable monomer are mixed and stirred uniformly to obtain prepolymer; Preparation of the first polymer: Add emulsifier and deionized water to a vessel and emulsify for 30 to 60 minutes under stirring to obtain a uniform and stable emulsion. Then, slowly add the prepolymer and initiator solution (the initiator potassium persulfate and / or ammonium persulfate is dissolved in deionized water to form a solution) prepared in the previous step. After the addition is complete, the temperature is raised to 90-110°C and kept at that temperature for 0.5 hours to react. Then, the mixture is cooled to 40°C, and the pH is adjusted to 7-8 with aqueous ammonia. The mixture is then filtered, discharged, and dried to obtain the polymer.

[0130] In some other embodiments of the present application, the first particles comprise silicone particles, the silicone particles comprise a second polymer, and the second polymer comprises a structural unit shown in formula (a): [ka] In formula (a), R 14 and R 15 includes one or more independently selected from substituted or unsubstituted C1-C10 alkyl groups, hydroxy or amino groups. 14 and R 15 each includes one or more independently selected from a substituted or unsubstituted C1-C6 alkyl group, a hydroxyl or an amino group.

[0131] In some embodiments of the present application, the second polymer comprises one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, polymethylaminosiloxane.

[0132] Exemplarily, the silicone particles include one or more of the structures shown in formula (a-1) to formula (a-5): [ka]

[0133] In this application, the terms "first polymer" and "second polymer" are used only to distinguish between types of materials, and have no limiting effect on the order or quantity.

[0134] In some embodiments of the present application, the number average molecular weight of the silicone particles is 35,000 to 70,000, and optionally 40,000 to 50,000. Illustratively, the number average molecular weight of the polymer may be 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, or a range consisting of any two of the above values. When the number average molecular weight of the silicone particles is in the above range, it has a relatively high viscosity, which is advantageous for improving the adhesive strength between the separator and positive and negative electrode plates when the silicone particles are applied to a separator. When the number average molecular weight of the silicone particles is within the above range, it is advantageous to form silicone particles with a relatively small particle size. When applied to a separator, a light and thin coating can be applied to the separator, reducing the overall thickness of the separator and thereby helping to improve the energy density of the battery. In addition, the particle size of the silicone particles formed by the polymer is not too small, which reduces the risk of the silicone particles blocking the substrate in the separator and improves the performance of the separator, such as its overall air permeability.

[0135] In the present application, the number average molecular weight of the first polymer can be measured by gel permeation chromatography (GPC). Specifically, the measurement is performed using a GPC1515 instrument manufactured by Waters, USA. The sample is dissolved in tetrahydrofuran, the dissolution time is 12 hours or more, the sample concentration is 4 mg / ml, and the sample is filtered to prepare the sample. The measurement temperature is 25°C, and the measurement flow rate is 1 ml / min.

[0136] The inventors have found through research that during the long-term charge-discharge cycle of a battery, moisture in the separator gradually releases into the electrolyte, which is highly sensitive to moisture and is prone to producing hydrofluoric acid (HF) upon contact with water, thereby increasing the acidity of the electrolyte, causing corrosion of the active material and current collector, and potentially causing the leaching of transition metal ions in the active material, thereby affecting the electrochemical performance of the battery. Therefore, the present application adjusts the moisture content of the silicone particles to 2500 μg / g or less, optionally between 700 μg / g and 2500 μg / g, calculated based on the mass of the silicone particles. When the moisture content of the silicone particles is within the above range, the moisture content is relatively low, reducing the risk of side reactions in the electrolyte during the long-term charge-discharge cycle of the battery, thereby improving the electrochemical performance of the battery. For example, the moisture content of the silicone particles may be 700 μg / g, 800 μg / g, 1000 μg / g, 1200 μg / g, 1500 μg / g, 1800 μg / g, 2000 μg / g, 2500 μg / g, or a range consisting of any two of the above values.

[0137] In the present application, the moisture content of the silicone particles can be measured using a moisture meter, and the test method may use the Karl Fischer moisture measurement method, and the test instrument may be a Karl Fischer moisture meter model 831 manufactured by Metrohm AG, Switzerland.

[0138] In some embodiments of the present application, the average particle size of the silicone particles is 3 μm or less, and optionally 0.01 μm to 2 μm. When the coating thickness is appropriate, the average particle size of the silicone particles within this range can ensure better contact between the particles. Furthermore, when the separator is heated, the pressure between the particles can effectively reduce the degree of shrinkage of the separator, further improving the thermal safety performance of the battery.

[0139] In some examples, the average particle size of the silicone particles is 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.80 μm, 0.85 μm, 0.9 μm, 0.95 μm, 1.0 μm, 1.05 μm, 1.1 μm, 1.15 μm, 1.2 μm, 1.25 μm, 1.3 μm, 1.35

[0047] The thickness may be, but is not limited to, 1.4 μm, 1.45 μm, 1.5 μm, 1.55 μm, 1.60 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.9 μm, 1.95 μm, 2.0 μm, 2.05 μm, 2.1 μm, 2.15 μm, 2.2 μm, 2.25 μm, 2.3 μm, 2.35 μm, 2.4 μm, 2.45 μm, 2.5 μm, 2.55 μm, 2.6 μm, 2.65 μm, 2.7 μm, 2.75 μm, 2.8 μm, 2.85 μm, 2.9 μm, 2.95 μm, 3.0 μm, or a range consisting of any two of the above numerical values. For example, the average particle size of the silicone particles may be 0.01 μm to 2 μm, 0.05 μm to 1.8 μm, 0.1 μm to 1.5 μm, or 0.3 μm to 1.2 μm.

[0140] In some embodiments of the present application, the specific surface area of the silicone particles is 12.0 m 2 / g or less, and selectively 5.0m 2 / g~10.0m 2 When the specific surface area of the silicone particles is within this range, the contact area with the electrolyte can be increased, which not only improves the electrolyte infiltration effect into the separator and the liquid retention effect in the separator, but also favors good contact between the particles and makes it easier to form a void structure between the silicone particles, which is favorable for the movement of active ions.

[0141] In some embodiments of the present application, the thickness of the substrate is 16 μm or less. Optionally, the thickness of the substrate is 3 μm to 12 μm. Because the coating of the present application can improve the thermal safety performance and cycle performance of the separator, a thinner substrate can be selected, thereby contributing to further improving the energy density of the battery.

[0142] In some embodiments of the present application, the substrate has a porous structure, and the porosity of the substrate is 25% or more. Optionally, the porosity of the substrate is 30% to 45%. When the porosity of the porous substrate is within the above appropriate range, it is advantageous to further improve the ion transport properties of the separator and improve the cycle performance of the battery.

[0143] The present application does not particularly limit the material of the substrate, and any known substrate having good chemical and mechanical stability can be selected. For example, the substrate may include at least one of a porous polyolefin resin film (e.g., at least one of polyethylene, polypropylene, and polyvinylidene fluoride), a porous glass fiber, and a porous nonwoven fabric. The porous substrate may be a single-layer film or a multi-layer composite film. When the porous substrate is a multi-layer composite film, the materials of each layer may be the same or different.

[0144] In some embodiments of the present application, the separator has a longitudinal heat shrinkage rate of 2% or less at 150°C for 1 hour.

[0145] In some embodiments of the present application, the separator has a transverse heat shrinkage of 2% or less at 150° C. for 1 hour.

[0146] In some of the above embodiments, the separator of the present application has low thermal shrinkage in both the transverse and longitudinal directions, which can further improve the thermal safety performance of the battery.

[0147] In some embodiments of the present application, the separator has an air permeability of 230 s / 100 cc or less. Optionally, the separator has an air permeability of 160 s / 100 cc to 200 s / 100 cc. The separator of the present application has good air permeability, which can improve ion transport properties, reduce battery resistance, and improve battery cycle performance.

[0148] In some embodiments of the present application, the separator has a longitudinal tensile strength of 2700 kg / cm 2 or more, and optionally 3000 kg / cm 2 ~4500kg / cm 2 is.

[0149] In some embodiments of the present application, the separator has a transverse tensile strength of 2000 kg / cm 2 or more, and optionally 2500 kg / cm 2 ~4500kg / cm 2 is.

[0150] In some embodiments of the present application, the separator has a wet length of 65 mm or more, and optionally 70 mm to 100 mm, and the separator of the present application has good electrolyte wetting properties, thereby improving ion transport properties and battery capacity.

[0151] In this application, the separator wetting length has a meaning known in the art and can be measured using methods known in the art. An exemplary test method is as follows: A separator is cut into a sample 5 mm wide and 100 mm long, and both ends of the sample are fixed and placed horizontally. 0.5 mg of electrolyte is dropped into the center of the sample. After a predetermined time (1 minute in this application), a photograph is taken to measure the diffusion length of the electrolyte, thereby obtaining the separator wetting length. To ensure the accuracy of the test results, multiple samples (e.g., 5 to 10) can be tested, and the test results are obtained by calculating the average value. The electrolyte may be prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, and then dissolving thoroughly dried LiPF6 in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0152] In some of the above embodiments, the separator of the present application has high tensile strength in both the transverse and longitudinal directions, which reduces the probability of the separator breaking when the battery expands, thereby further improving the safety performance of the battery.

[0153] In this application, the heat shrinkage rate, tensile strength, and air permeability of the separator all have meanings known in the art and can be measured using methods known in the art, for example, they may be tested in accordance with standard GB / T 36363-2018.

[0154] In some embodiments of the present application, the separator has an ionic conductivity of 0.8 S / m to 1.5 S / m. The ionic conductivity of the separator within the above range can contribute to improving the cycle performance of the battery.

[0155] The ionic conductivity of a separator can be determined by testing it using an AC impedance spectroscopy experiment. Specifically, the separator is cut into a circular sheet of a certain area, dried, and then placed between two stainless steel electrodes. After absorbing a sufficient amount of electrolyte, the sheet is sealed to form a button battery, and an AC impedance spectroscopy experiment is performed. The intersection of the linear portion of the AC impedance spectrum and the real axis is the bulk resistance of the electrolyte, and the ionic conductivity of the separator can be calculated using the formula σ = (L / A) × R. L is the thickness of the separator (cm), and A is the contact area between the stainless steel electrodes and the separator (cm). 2 ), R denotes the bulk resistance (mS) of the electrolyte.

[0156] The electrolyte solution used may be prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, dissolving thoroughly dried LiPF6 in the organic solvent, and preparing an electrolyte solution with a concentration of 1 mol / L.

[0157] It should be noted that the above separator coating parameters are all coating parameters for one side of the substrate.

[0158] When the coating is applied to both sides of the substrate, if the coating parameters on either side meet the present application, it is considered to fall within the protection scope of the present application.

[0159] Separator manufacturing method A second aspect of the present application provides a method for manufacturing the separator of the first aspect of the present application, including the steps of: providing a substrate in S1; mixing organic particles as first particles and second particles having a pore structure in a solvent in S2 to prepare a coating slurry; and applying the coating slurry to at least one side of the substrate to form a slurry film layer and drying the slurry film layer to form a coating, thereby obtaining a separator in S3.

[0160] In some embodiments of the present application, the solvent in S2 may be water, for example, deionized water. The adhesive may be a water-based adhesive, which has the advantages of high thermodynamic stability and environmental friendliness, making it advantageous for the production and application of the coating slurry. For example, the water-based adhesive may include at least one of a water-based acrylic resin (e.g., a homopolymer of acrylic acid, methacrylic acid, or sodium acrylate monomer or a copolymer with other copolymerizable monomers), polyvinyl alcohol (PVA), an isobutylene-maleic anhydride copolymer, and polyacrylamide. The coating slurry may also include other components, such as a dispersant and a wetting agent.

[0161] In some embodiments of the present application, a coater is used for coating in S3. The present application does not particularly limit the model number of the coater, and for example, a commercially available coater may be used. Optionally, the coater includes an intaglio roller, which is used to transfer the coating slurry onto the substrate. Optionally, the intaglio roller has a line count of 180 LPI to 250 LPI, and more optionally, 190 LPI to 240 LPI. Furthermore, the coating method may be transfer coating, rotary spray coating, dip coating, or the like.

[0162] Each of the above process parameters can be controlled within a given range to further improve the performance of the separator of the present application. Those skilled in the art may selectively adjust and control one or more of the above process parameters according to the actual production situation.

[0163] The separator manufacturing method of the present application produces and obtains a coating in a single application, greatly simplifying the separator manufacturing process flow.

[0164] Parameters such as some of the raw materials used in the manufacturing method of the separator of the present application and their contents can be referred to the separator of the first aspect of the embodiment of the present application, and will not be further described here. Unless otherwise specified, each raw material used in the manufacturing method of the separator of the present application can be purchased as a commercially available product.

[0165] secondary battery A third aspect of the present application provides a secondary battery. A secondary battery, also known as a rechargeable battery or storage battery, is a battery that can be continuously used by activating the active material through charging after discharging. Generally, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate and serves to prevent short circuits between the positive electrode and the negative electrode while allowing active ions to pass through.

[0166] The present application is not particularly limited to the type of secondary battery. For example, the secondary battery may be a lithium ion battery, a sodium ion battery, etc., and in particular, the secondary battery may be a lithium ion secondary battery.

[0167] The secondary battery of the present application includes the separator of the first aspect of the present application or a separator obtained by the manufacturing method of the second aspect of the present application, the separator being interposed between a positive electrode plate and a negative electrode plate, and optionally having the coating of the present application on at least one side of the separator close to the negative electrode plate, thereby providing the secondary battery of the present application with relatively excellent thermal safety performance and cycle performance.

[0168] [Positive electrode plate] In some embodiments of the present application, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has opposite sides in its thickness direction, and the positive electrode film layer is disposed on one or both of the two opposing surfaces of the positive electrode current collector.

[0169] When the secondary battery of the present application is a lithium-ion secondary battery, the positive electrode active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and their modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their modified compounds.

[0170] In some embodiments of the present application, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium-ion secondary battery may have a general formula of Li a Ni b Co c M d O e A f and may include at least one of the lithium transition metal oxides and their modified compounds. Here, 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M is at least one selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is at least one selected from N, F, S, and Cl.

[0171] As an example, the positive electrode active material used in the lithium-ion secondary battery may be LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may contain at least one of O2, LiFePO4, and LiMnPO4.

[0172] When the secondary battery of the present application is a sodium-ion secondary battery, the positive electrode active material may include at least one of a sodium-containing transition metal oxide, a polyanion material (e.g., phosphate, fluorophosphate, pyrophosphate, sulfate, etc.), and a Prussian blue-based material, but is not limited thereto.

[0173] For example, the positive electrode active materials used in sodium ion secondary batteries are NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, general formula X p M' q (PO4) r O x Y 3-x The compound may contain at least one material represented by the general formula X p M' q (PO4) r O x Y 3-x In, 0 <p≦4、0<q≦2、1≦r≦3、0≦x≦2であり、Xは、H + , Li + , Na + , K. + and NH4 +wherein M' is a transition metal cation, optionally at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn; and Y is a halogen anion, optionally at least one of F, Cl, and Br.

[0174] In the present application, the modifying compounds for the positive electrode active materials are those that modify the positive electrode active materials by doping and / or surface coating.

[0175] In some embodiments of the present application, the positive electrode film layer optionally further includes a positive electrode conductive agent. The present application is not particularly limited by the type of positive electrode conductive agent, and examples of the positive electrode conductive agent include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments of the present application, the mass percentage content of the positive electrode conductive agent is ≦6 wt %, based on the total weight of the positive electrode film layer.

[0176] In some embodiments of the present application, the positive electrode membrane layer optionally further includes a positive electrode adhesive. The present application is not particularly limited to the type of positive electrode adhesive. For example, the positive electrode adhesive 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 a fluorine-containing acrylate resin. In some embodiments of the present application, the mass percentage content of the positive electrode adhesive is ≦5 wt %, based on the total weight of the positive electrode membrane layer.

[0177] In some embodiments of the present application, the positive electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet is aluminum foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one side of the polymer base layer. For example, the metal layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0178] The positive electrode film layer is typically obtained by coating a positive electrode slurry on a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive, and any other optional components in a solvent and stirring the resulting mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0179] [Negative electrode plate] In some embodiments of the present application, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has opposite sides in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0180] The negative electrode active material may be any negative electrode active material for secondary batteries known in the art. For example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may include at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy material. The tin-based material may include at least one of a tin element, a tin oxide, and a tin alloy material.

[0181] In some embodiments of the present application, the negative electrode film layer optionally further includes a negative electrode conductive agent. The present application is not particularly limited to the type of the negative electrode conductive agent, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments of the present application, the mass percentage content of the negative electrode conductive agent is ≦7 wt %, based on the total weight of the negative electrode film layer.

[0182] In some embodiments of the present application, the negative electrode film layer optionally further includes a negative electrode adhesive. The present application is not particularly limited to the type of negative electrode adhesive. For example, the negative electrode adhesive may include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble acrylic acid-based resin (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments of the present application, the mass percentage content of the negative electrode adhesive is ≦6 wt %, based on the total weight of the negative electrode film layer.

[0183] In some embodiments of the present application, the negative electrode membrane layer optionally further contains other additives. For example, the other additives may include thickeners such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc. In some embodiments of the present application, the mass percentage content of the other additives is ≦3 wt %, based on the total weight of the negative electrode membrane layer.

[0184] In some embodiments of the present application, the negative electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet is copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one side of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0185] The negative electrode film layer is typically obtained by coating a negative electrode slurry on a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing a negative electrode active material, an optional conductive agent, an optional adhesive, and other optional auxiliary agents in a solvent and stirring the resulting mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0186] The negative electrode plate does not exclude additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode plate of the present application further includes a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode plate of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0187] [Electrolyte] During the charge and discharge process of the secondary battery, active ions are absorbed and released by moving back and forth between the positive and negative electrodes, and the electrolyte serves to conduct the active ions between the positive and negative electrodes. The present application does not particularly limit the type of electrolyte, and it can be selected according to actual needs.

[0188] The electrolyte solution includes an electrolyte salt and a solvent, and the types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.

[0189] When the secondary battery of the present application is a lithium-ion secondary battery, for example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0190] When the secondary battery of the present application is a sodium-ion secondary battery, for example, the electrolyte salt may include at least one of sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPOF), sodium difluorobis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP).

[0191] By way of example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0192] In some embodiments of the present application, the electrolyte solution may further optionally contain additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve some performance of the secondary battery, such as an additive that improves the overcharge performance of the secondary battery, an additive that improves the high-temperature performance of the secondary battery, or an additive that improves the low-temperature power performance of the secondary battery.

[0193] In some embodiments of the present application, the positive electrode plate, separator and negative electrode plate may be fabricated into an electrode assembly by a winding process and / or a stacking process.

[0194] In some embodiments of the present application, the secondary battery may further include an exterior body, which may be used to package the electrode assembly and the electrolyte solution.

[0195] In some embodiments of the present application, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, or a steel case. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0196] The present application does not particularly limit the shape of the secondary battery, and the secondary battery may be cylindrical, rectangular, or any other shape. Figure 1 shows an example of a secondary battery 5 having a rectangular structure.

[0197] In some embodiments of the present application, as shown in FIG. 2 , the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 is used to cover the opening and seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process and / or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and can be adjusted as needed.

[0198] The method for manufacturing the secondary battery of the present application is well known. In some embodiments of the present application, a secondary battery can be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. For example, the positive electrode plate, the separator, and the negative electrode plate can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly can be placed in an outer casing, dried, and then injected with an electrolyte. The secondary battery can be obtained through processes such as vacuum packaging, standing, chemical formation, and shaping.

[0199] In some embodiments of the present application, the secondary battery according to the present application can be assembled into a battery module, and the number of secondary batteries included in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0200] Fig. 3 is a schematic diagram of an example battery module. As shown in Fig. 3, in a battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0201] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0202] In some embodiments of the present application, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0203] 4 and 5 are schematic diagrams of an example battery pack 1. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0204] power consumption equipment A fourth aspect of the present application provides a power consuming device, the power consuming device including at least one of the secondary battery, battery module, or secondary battery pack of the third aspect of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0205] The power consumption device may select a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0206] 6 is a schematic diagram of an example power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, that may employ a battery pack or battery module to meet the high power and high energy density demands of the power consuming device.

[0207] Other examples of power consuming devices include mobile phones, tablet computers, notebook computers, etc. These power consuming devices generally require a thin design and can employ secondary batteries as their power source.

[0208] The following embodiments more specifically describe the contents disclosed in this application, and these embodiments are merely for the purpose of discussion and illustration, because various modifications and variations within the scope of the contents disclosed in this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments can be obtained commercially or synthesized according to conventional methods and can be used directly without further treatment, and all equipment used in the embodiments can be obtained commercially.

[0209] Example 1-1 Silicone particle production Preparation of prepolymer: 1500g of deionized water and 7.5g of sodium dodecyl sulfate were added to a 5L three-neck flask, and emulsified at a rotation speed of 1800r / min for 40 minutes to obtain a uniform and stable emulsion. Next, 688.72g of methyl acrylate, 26.53g of acrylonitrile, and 995.25g of methacryloyloxypropyl cage-type polysilsesquioxane (the molar ratio of methyl acrylate, acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane is 16:1:3) were added in sequence, and the mixture was stirred at a rotation speed of 1800r / min for 40 minutes to obtain a uniform prepolymer.

[0210] Preparation of polymer: 4.5g of sodium dodecyl sulfate and 1500g of deionized water were added to a dry three-neck flask, and emulsified for 40 minutes under high-speed stirring to obtain a uniform and stable emulsion. Then, using a peristaltic pump, the prepolymer and initiator solution (4.5g of potassium persulfate dissolved in 45g of deionized water to form a solution) prepared in the previous step were slowly added dropwise. After the addition was completed, the temperature was raised to 90°C and kept at that temperature for 1 hour to react. Then, the mixture was cooled to 40°C, and the pH was adjusted to 7-8 with aqueous ammonia. The mixture was then filtered, discharged, and dried to produce silicone particles with a number average molecular weight of 52763, which were designated as F1.

[0211] Here, the average particle size of the silicone particles F1 is 0.8 μm, the water content is 800 μg / g, and the specific surface area is 8 g / m 2 It was.

[0212] Separator manufacturing The PE substrate was provided with a thickness of 6.0 μm and a porosity of 35%.

[0213] Preparation of coating slurry: The silicone particles F1 prepared above and ZIF-8 particles were mixed in water in a weight ratio of 5:1 to prepare a coating slurry, in which the average pore size of the ZIF-8 particles was 1 nm and the porosity was 30%.

[0214] Coating: The prepared coating slurry was applied to both sides of the PE substrate using a coater, and then dried and slit to obtain a separator.

[0215] Positive electrode plate manufacturing The active material is LiNi 0.8 Mn 0.1 Co 0.1 O2 (NCM811), acetylene black as a conductive agent, and polyvinylidene fluoride as an adhesive were uniformly mixed in an appropriate amount of solvent N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 to obtain a positive electrode slurry. The positive electrode slurry was then applied to a positive electrode current collector aluminum foil, and after processes such as drying, cold pressing, slitting, and cutting, a positive electrode plate was obtained.

[0216] Negative electrode plate manufacturing The negative electrode active material, artificial graphite, the conductive agent, carbon black (Super P), the adhesive, styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC), were uniformly mixed in a mass ratio of 95:2:2:1 in an appropriate amount of deionized water solvent to obtain a negative electrode slurry. The negative electrode slurry was then applied to a negative electrode current collector copper foil, and the negative electrode plate was obtained after drying, cold pressing, slitting, and cutting processes.

[0217] Electrolyte production Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70 to obtain an organic solvent, and thoroughly dried LiPF6 was dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0218] Secondary battery manufacturing A positive electrode plate, a separator, and a negative electrode plate were stacked in this order and wound to obtain an electrode assembly. The electrode assembly was then placed in an outer casing, dried, and then an electrolyte was added. After undergoing processes such as vacuum packaging, standing, chemical conversion, and shaping, a secondary battery was obtained.

[0219] Examples 1-2 to 1-11 It was manufactured in a similar manner to Example 1-1, with the difference being the parameters related to the coating of the separator, the details of which are shown in Table 1.

[0220] Comparative Example 1-1 It was prepared in a similar manner to Example 1-1, except that the parameters related to the separator coating were outside the scope of protection of claim 1, i.e., the first particles were silicone particles F1, and the second particles were non-porous aluminum oxide, and the detailed parameters were as shown in Table 1.

[0221] Examples 2-1 to 2-4 It was manufactured in a similar manner to Example 1-1, except for the content of the first particles and the second particles contained in the coating of the separator. The detailed parameters are as shown in Table 2.

[0222] Comparative Example 2-1 It was manufactured in a similar manner to Example 2-1, except for the content of the first particles and the second particles contained in the coating of the separator. The detailed parameters are as shown in Table 2.

[0223] Testing section (1) Separator heat shrinkage test The thermal shrinkage rate of the separator can be tested in accordance with GB / T 36363-2018. The specific test procedure is as follows: Sample preparation: The separator prepared above is punched into samples 50 mm wide and 100 mm long along the TD and MD directions using a press, and five parallel samples are placed on A4 paper. The A4 paper containing the samples is then placed on a cardboard box with a thickness of 1 mm to 5 mm.

[0224] Sample test: Set the temperature of the blast oven to 150°C. After the temperature reaches the set temperature and stabilizes for 30 minutes, place an A4 size sheet of paper on a piece of cardboard into the blast oven and start timing. After the set time (1 hour in this application) is reached, measure the length and width of the separator and mark the values as a and b respectively.

[0225] Calculation of heat shrinkage rate: Machine direction (MD) heat shrinkage rate = [(100-a) / 100] x 100%, Transverse direction (TD) heat shrinkage rate = [(50-b) / 50] x 100%, the average value of five parallel samples is taken as the test result.

[0226] (2) Separator ionic conductivity test The ionic conductivity of a separator can be determined by testing it using an AC impedance spectroscopy experiment. Specifically, the separator is cut into a circular sheet of a certain area, dried, and then placed between two stainless steel electrodes. After absorbing a sufficient amount of electrolyte, the sheet is sealed to form a button battery, and an AC impedance spectroscopy experiment is performed. The intersection of the linear portion of the AC impedance spectrum and the real axis is the bulk resistance of the electrolyte, and the ionic conductivity of the separator can be calculated using the formula σ = (L / A) × R. L is the thickness of the separator (cm), and A is the contact area between the stainless steel electrodes and the separator (cm). 2 ), R denotes the bulk resistance (mS) of the electrolyte.

[0227] The electrolyte solution used may be prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, dissolving thoroughly dried LiPF6 in the organic solvent, and preparing an electrolyte solution with a concentration of 1 mol / L.

[0228] (3) Battery capacity retention rate test At 25°C, the battery is charged to 4.3V at a constant current of 1 / 3C, then charged at a constant voltage of 4.3V until the current reaches 0.05C, left to stand for 5 minutes, and then discharged to 2.8V at 1 / 3C. The resulting capacity is designated as the initial capacity C0. The above steps are repeated for 1000 cycles, and the discharge capacity C of the battery is 1000 At the same time, the battery capacity retention rate P after 1000 cycles was recorded. 1000 =C 1000 / C0*100%.

[0229] Table 1 (Tables 1-1, 1-2) lists the test results under different parameters of the coatings in Examples 1-1 to 1-5 and Comparative Example 1-1, respectively.

[0230] [Table 1-1] [Table 1-2]

[0231] As can be seen from Table 1, in the separator of the present application, the first particles in the coating are organic particles, which have relatively good heat resistance. When the separator shrinks due to heat, the first particles, the second particles, and / or the first and second particles in the coating may come into contact with each other due to the shrinkage of the substrate, and this can provide a force on the substrate in the direction opposite to the shrinkage, thereby reducing the degree of separator shrinkage, reducing the risk of short-circuiting between the positive and negative electrodes in the battery, and improving the thermal safety performance of the battery. Furthermore, the second particles, which have a porous structure, can store the electrolyte and improve the separator's liquid absorption and retention rates, and the pores can act as ion channels for ion transport, allowing the battery to achieve both good heat resistance and better cycle performance.

[0232] Table 2 lists the test results when the coatings of Examples 1-1, 2-1 to 2-4 and Comparative Example 2-1 contain different weight amounts of silicone particles F1 and ZIF-8, respectively.

[0233] [Table 2]

[0234] As can be seen from Table 2, the weight of the organic particles in the coating is relatively large compared to the weight of the second particles, which not only reduces the degree of shrinkage of the separator and contributes to improving the thermal safety performance of the battery, but also allows better contact between the organic particles, forming more ion transport channels between the particles, and further improving the ionic conductivity of the separator, thereby improving the cycle performance of the battery.

[0235] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiments that have substantially the same configuration as the technical idea and achieve the same effects within the scope of the technical solution of the present application are included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods constructed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0236] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: cover plate.

Claims

1. A separator, A substrate; a coating disposed on at least one side of the substrate, the coating comprising first particles and second particles, wherein the first particles are organic particles and the second particles have a pore structure.

2. The separator according to claim 1, wherein the average pore size of the second particles is from 0.1 nm to 10 nm, and optionally from 0.4 nm to 5 nm.

3. 3. The separator according to claim 1, wherein the porosity of the second particles is 10% to 60%, and optionally 30% to 50%.

4. 4. The separator according to claim 1, wherein the second particles have an average particle size of 2 μm or less, and optionally 0.1 μm to 1 μm.

5. The specific surface area of the second particles is 100 m ２ / g or more, and optionally 500m ２ / g to 2000m ２ The separator according to claim 1 , wherein the tensile strength is 1 / g.

6. 6. The separator according to claim 1, wherein a ratio of a weight ratio A of the first particles to a weight ratio B of the second particles, based on the weight of the coating, satisfies 1<A / B≦20, and optionally satisfies 5≦A / B≦15.

7. The separator according to any one of claims 1 to 6, wherein the weight ratio B of the second particles in the coating is 20% or less, and optionally 0.1% to 15%.

8. the second particles comprise one or more of inorganic particles and metal-organic framework materials; Optionally, the inorganic particles include one or more of titanium oxide, zirconium oxide, barium oxide, magnesium oxide, barium sulfate, magnesium aluminum silicate, zirconium titanate, barium titanate; 8. The separator of any one of claims 1 to 7, optionally wherein the metal-organic framework material comprises one or more of IRMOFs, ZIFs, MILs, PCNs, CPLs, UiOs.

9. The separator according to claim 1 , wherein the second particles have a through-hole structure.

10. 10. The separator according to claim 1, wherein the first particles include one or more of silicone particles, melamine formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles, and optionally the first particles include silicone particles.

11. the first particles comprise silicone particles, and the silicone particles comprise a first polymer, the first polymer comprising a first structural unit, a second structural unit, and a third structural unit; The first structural unit has a structure shown in formula (I): 【Chemical 1】 In formula (I), R １ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R １ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; R ２ comprises one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C1-C20 hydroxyalkyl group, and optionally R ２ comprises one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, a C1-C12 hydroxyalkyl group; The second structural unit is as shown in formula (II): 【Chemistry 2】 In formula (II), R ３ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R ３ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; The third structural unit is as shown in formula (III): 【Chemistry 3】 In formula (III), R ４ From R １１ each independently comprises a substituted or unsubstituted C1-C10 alkyl group or one or more structural units shown in formula (III-1), wherein R ４ From R １１ At least one of the structural units is represented by formula (III-1): 【Chemistry 4】 In formula (III-1), R １２ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and optionally R １２ contains one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; R １３ comprises a substituted or unsubstituted C1-C10 alkyl group, optionally R １３ The separator according to any one of claims 1 to 10, wherein comprises a substituted or unsubstituted C3-C10 alkyl group.

12. the molar content of the first structural unit is expressed as a %, based on the total molar amount of the first structural unit, the second structural unit and the third structural unit, and is 70≦a≦90, optionally 75≦a≦85; and / or the molar content of the second structural unit is expressed as b %, based on the total molar amount of the first structural unit, the second structural unit and the third structural unit, where 0<b≦16, optionally 5≦b≦15; and / or The separator according to claim 11, wherein the molar content of the third structural unit is expressed as c %, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and is 2≦c≦15, optionally 5≦c≦10.

13. Based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is represented as a %, the molar content of the second structural unit is represented as b %, and the molar content of the third structural unit is represented as c %, and the silicone particles satisfy conditions (1) to (3), (1) the condition that 4≦a / b≦15; (2) the condition that 5≦a / c≦14; (3) a:b:c is (13-16):(1-3):(3-4).

14. the first particles comprise silicone particles, and the silicone particles comprise a second polymer, the second polymer comprising a structural unit shown in formula (a), 【Chemistry 5】 In formula (a), R １４ and R １５ each independently comprise one or more of a substituted or unsubstituted C1-C10 alkyl group, hydroxy or amino group, and optionally R １４ and R １５ each independently comprises one or more of a substituted or unsubstituted C1-C6 alkyl group, hydroxy, or amino group; Optionally, the second polymer comprises one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, polymethylaminosiloxane.

15. The separator according to any one of claims 10 to 14, wherein the number average molecular weight of the silicone particles is 35,000 to 70,000, and optionally 40,000 to 55,000.

16. 16. The separator according to claim 10, wherein the moisture content of the silicone particles is 2500 μg / g or less, and optionally 700 μg / g to 2000 μg / g, based on the mass of the silicone particles.

17. The separator according to any one of claims 10 to 16, wherein the silicone particles have an average particle size of 3 µm or less, and optionally 0.01 µm to 2 µm.

18. The specific surface area of the silicone particles is 12.0 m ２ / g or less, and optionally 5.0m ２ / g to 10.0m ２ The separator according to any one of claims 10 to 17, wherein the tensile strength is 1 / g.

19. The separator according to any one of claims 1 to 18, wherein the thickness of the substrate is 16 µm or less, and optionally 3 µm to 12 µm.

20. The separator according to any one of claims 1 to 19, wherein the porosity of the substrate is 25% or more, and optionally 30% to 45%.

21. The separator is (1) The separator has a longitudinal heat shrinkage rate of 2% or less at 150°C for 1 hour; (2) The separator has a transverse heat shrinkage rate of 2% or less at 150°C for 1 hour; (3) The separator has an air permeability of 230 s / 100 cc or less, and optionally 160 s / 100 cc to 200 s / 100 cc; (4) The longitudinal tensile strength of the separator is 2700 kg / cm ２ or more, and optionally 3000 kg / cm ２ ~4500kg / cm ２ The characteristic that (5) The separator has a lateral tensile strength of 2000 kg / cm ２ or more, and optionally 2500 kg / cm ２ ~4500kg / cm ２ The characteristic that (6) The wet length of the separator is 65 mm or more, and optionally 70 mm to 100 mm; (7) The separator according to any one of claims 1 to 20, wherein the separator has an ionic conductivity of 0.8 S / m to 1.5 S / m.

22. Providing a substrate; Mixing organic particles as first particles and second particles having a pore structure in a solvent to prepare a coating slurry; 22. The method for producing a separator according to claim 1, comprising: applying the coating slurry to at least one side of the substrate to form a slurry film layer; and drying the slurry film layer to form a coating, thereby obtaining a separator.

23. A secondary battery comprising the separator according to any one of claims 1 to 21 or the separator obtained by the manufacturing method according to claim 22.

24. 24. A power consuming device comprising the secondary battery of claim 23.

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