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

Abstract

The present application provides a separator, a method for manufacturing the same, a secondary battery, and a power consumption device. The separator includes a base material and a coating provided on at least one side of the base material. The coating includes first particles and second particles. The first particles are organic particles, and the average particle diameter D1 of the first particles and the average particle diameter D2 of the second particles satisfy 1 < D1 / D2 ≤ 10. The separator has excellent heat resistance and good wetting and liquid retention effects with respect to the electrolyte, thereby imparting excellent thermal safety and cycle characteristics to the secondary battery.

Description

Technical Field

[0001] This application belongs to the technical field of secondary batteries, and specifically relates to a separator, a method for manufacturing the same, a secondary battery, and a power consumption device.

Background Art

[0002] In recent years, secondary batteries have excellent electrochemical properties and safety characteristics, etc., and are widely used in power consumption devices such as electric tools, electric vehicles, and energy storage devices.

[0003] With the popularization and application of secondary batteries, the requirements for their performance are becoming increasingly high. However, in related technologies, when the temperature of a secondary battery rises, its thermal safety decreases, and further safety problems are caused. In addition, the cycle characteristics decrease due to the temperature rise of the secondary battery, and the secondary battery cannot meet the current needs.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of this application is to provide a separator, a method for manufacturing the same, a secondary battery, and a power consumption device, which have excellent heat resistance and a good wetting effect and liquid retention effect on the electrolyte, so that the secondary battery has excellent thermal safety and cycle characteristics.

Means for Solving the Problems

[0005] The first aspect of this application provides a separator including a base material and a coating provided on at least one side of the base material, the coating containing first particles and second particles, the first particles being organic particles, when the average particle diameter of the first particles is D1 and the average particle diameter of the second particles is D2, satisfying 1 < D1 / D2 ≤ 10.

[0006] In the separator according to the present application, the first particles are organic particles, and the coating satisfies the above relationship, thereby allowing the first and second particles to overlap well in the coating. When the substrate shrinks due to heat, the organic particles have excellent heat resistance. Furthermore, the organic particles, the second particles, and / or the organic particles and the second particles rapidly press against each other, applying a force to the substrate in the direction opposite to the shrinkage direction, thereby improving the thermal safety of the secondary battery. Furthermore, the second particles filling the spaces between the first particles creates many voids in the coating, further improving the wetting effect of the electrolyte on the separator, which is beneficial for promoting ion conduction within the separator and improving the cycle characteristics of the secondary battery.

[0007] In any embodiment of the present application, the coating satisfies 2≦D1 / D2≦8, and optionally 3≦D1 / D2≦7. When the coating satisfies the above relationship, the particles can be more easily overlapped with each other, and when the substrate shrinks due to heat, the particles quickly contact and press against each other, applying a force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and increasing the deformation resistance of the substrate, thereby reducing the probability of short-circuiting between the positive and negative electrodes of the secondary battery and further improving the thermal safety of the secondary battery.

[0008] In any embodiment of the present application, 0.02 μm≦D1≦3 μm, and optionally 0.5 μm≦D1≦2 μm. When the average particle diameter D1 of the first particles is in the above appropriate range, the electrolyte wets the separator, contributing to imparting cycle characteristics to the secondary battery, contributing to particle overlap, and further, when the separator is subjected to heat, a force opposite to the direction in which the separator is subjected to heat is applied in a timely manner, thereby reducing the degree of shrinkage when the separator is subjected to heat and improving the thermal safety of the secondary battery.

[0009] In any embodiment of the present application, 0.01 μm≦D2≦2 μm, and optionally 0.1 μm≦D2≦1 μm. When the average particle diameter D2 of the second particles is in the above appropriate range, the electrolyte wets the separator, contributing to imparting cycle characteristics to the secondary battery, and also contributing to particle overlap. Furthermore, when the separator is subjected to heat, a force opposite to the direction in which the separator is subjected to heat is timely provided, thereby reducing the degree of shrinkage when the separator is subjected to heat and improving the thermal safety of the secondary battery.

[0010] In any embodiment of the present application, the volume distribution particle size of the first particles may be 1 v90≦3.0 μm, and optionally, 0.1 μm≦D 1 The volume distribution particle diameter D of the first particles is 2.0 μm or less. 1 By having v90 within the above range, the bulk density can be improved, the coating thickness can be made appropriate, and the energy density of the secondary battery can be improved.

[0011] In any embodiment of the present application, the volume distribution particle size of the first particles may be 1 v50≦2 μm, and optionally, 0.01 μm≦D 1 The volume distribution particle diameter D of the first particles is v50≦1.5 μm. 1 When v50 is in the above range, it can contribute to strengthening the intimate contact between the first particles, causing adjacent particles to overlap each other. When the substrate shrinks due to heat, the particles quickly contact and press against each other, applying an acting force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and improving the deformation resistance of the substrate, thereby reducing the probability of short-circuiting between the positive and negative electrodes of the secondary battery and further improving the thermal safety of the secondary battery.

[0012] In any embodiment of the present application, the specific surface area of the first particles is 3 m 2 / g or more, and optionally, 10m 2 / g~100m 2When the specific surface area of the first particles is in the above-described appropriate range, the contact area between the first particles and the electrolyte can be increased, which further contributes to improving the wetting effect and liquid retention effect of the electrolyte on the separator.

[0013] In any embodiment of the present application, the particle size distribution of the first particles may be: (D 1 v90-D 1 v10) / D 1 v50≦1.5, and optionally 0.5≦(D 1 v90-D 1 v10) / D 1 v50≦1.0.

[0014] In any embodiment of the present application, the volume distribution particle size of the second particles may be 2 v90≦2 μm, and optionally, 0.3 μm≦D 2 v90≦1.5 μm.

[0015] In any embodiment of the present application, the volume distribution particle size of the second particles may be 2 v50≦1.5 μm, and optionally 0.2 μm≦D 2 v50≦1 μm.

[0016] In any embodiment of the present application, the specific surface area of the second particles is 10 m 2 When the specific surface area of the second particles is in the above-described appropriate range, the contact area between the second particles and the electrolyte can be increased, which contributes to improving the wetting effect and liquid retention effect of the electrolyte on the separator.

[0017] In any embodiment of the present application, the particle size distribution of the second particles may be: (D 2 v90-D 2 v10) / D 2 v50≦1.0, and optionally 0.2≦(D 2 v90-D 2 v10) / D 2 v50≦0.8.

[0018] In any embodiment of the present application, where the weight fraction of the first particles in the coating is A and the weight fraction of the second particles in the coating is B, the coating may be

[0019] In any embodiment of the present application, where A is the weight fraction of the first particles in the coating and B is the weight fraction of the second particles in the coating, the coating satisfies A≧50%, optionally 70%≦A≦90%, and / or the coating satisfies B≦35%, optionally 5%≦B≦25%.

[0020] In any embodiment of the present application, the first particles include one or more of organic silicone resin 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. Optionally, the first particles include organic silicone resin particles.

[0021] In any embodiment of the present application, the first particles comprise organosilicone resin particles, the organosilicone resin particles comprise a first polymer, and the first polymer comprises a first structural unit, a second structural unit, and a third structural unit.

[0022] The first structural unit has a structure represented by formula (I). Formula (I) [ka] (In formula (I), R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R1 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl; ​R2 includes one or more of substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, and substituted or unsubstituted C1-C20 hydroxyalkyl, and optionally R2 includes one or more of C1-C12 alkyl, C3-C12 cycloalkyl, and C1-C12 hydroxyalkyl. The second structural unit is represented by formula (II). Formula (II) [ka] (In formula (II), R3 includes one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R3 includes one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl.) The third structural unit is represented by formula (III). Formula (III) [ka] (In formula (III), R4 to R 11 each independently contains one or more structural units selected from substituted or unsubstituted C1 to C10 alkyl and 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), Formula (III-1) [ka] In formula (III-1), R12 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, optionally R12 comprises one or more of a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl, and R13 is selected from a substituted or unsubstituted C1-C10 alkyl, optionally R13 is selected from a substituted or unsubstituted C3-C10 alkyl.

[0023] 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, if the molar content of the first structural unit is a%, then 65 ≦ a ≦ 95, optionally 70 ≦ a ≦ 85, and / or, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, if the molar content of the second structural unit is b%, then 0 < b ≦ 15, optionally 5 ≦ b ≦ 10, and / or, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, if the molar content of the third structural unit is c%, then 0 < c ≦ 10, optionally 5 ≦ c ≦ 9.

[0024] 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, when the molar content of the first structural unit is a%, the molar content of the second structural unit is b%, and the molar content of the third structural unit is c%, the organosilicon resin particles satisfy one or more of conditions (1) to (3): (1) 7 ≦ a / b ≦ 14; (2) 8 ≦ a / c ≦ 16; (3) a:b:c is (13 - 15):(2 - 4):(2 - 4).

[0025] In any embodiment of the present application, the organosilicon resin particles further contain a second polymer, and the second polymer contains a structural unit represented by formula (a). Formula (a)

Chemical formula

[0026] Optionally, the second polymer comprises one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, and polymethylaminosiloxane.

[0027] In any embodiment of the present application, the number-average molecular weight of the organic silicone resin particles is 30,000 to 70,000, and optionally 40,000 to 50,000. A number-average molecular weight within this range is advantageous for forming organic silicone resin particles with small particle sizes. When these organic silicone resin particles are used in separators, this is advantageous for applying a thin coating to the separator and reducing the overall thickness of the separator, thereby facilitating an improvement in the energy density of secondary batteries. It also reduces the risk of the organic silicone resin particles clogging the separator substrate, achieving the goal of improving the overall separator's properties, such as its air permeability.

[0028] In any embodiment of the present application, the moisture content of the organosilicone resin particles is 3000 μg / g or less, and optionally 600 μg / g to 2800 μg / g, based on the weight of the organosilicone resin particles.

[0029] In any embodiment of the present application, the second particles include one or more of inorganic particles, polymeric particles, and optionally, the second particles include inorganic particles.

[0030] In any embodiment of the present application, the inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or greater, inorganic particles capable of conducting active ions, and inorganic particles capable of undergoing electrochemical oxidation and reduction.

[0031] In any embodiment of the present application, the polymer particles include one or more of organosilicone resin 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.

[0032] In any embodiment of the present application, the thickness of the substrate is 16 μm or less, and optionally 3 μm to 9 μm.

[0033] In any embodiment of the present application, the porosity of the substrate is 20% or more, optionally 25% to 45%.

[0034] In any embodiment of the present application, the thickness of the coating is 0.1 μm to 5 μm, and optionally 0.5 μm to 3 μm. When the thickness H of the coating is in the above range, the degree of dense packing between particles in the coating is improved, which further contributes to improving the thermal safety of the secondary battery.

[0035] In any embodiment of the present application, the porosity of the coating is 20% or more, and optionally 25% to 50%. When the coating contains organic silicone resin particles, a porosity of the coating within the above range can further improve the wetting and retention of the electrolyte solution on the separator, which is advantageous for ion conduction in the separator and improves the cycle characteristics of the secondary battery.

[0036] In any embodiment of the present application, the separator has a longitudinal heat shrinkage rate of 3% or less at 150°C for 1 hour.

[0037] 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.

[0038] In any embodiment of the present application, the air permeability of the separator is 200 s / 100 mL or less, and optionally, it is 150 s / 100 mL to 200 s / 100 mL.

[0039] In any embodiment of the present application, the longitudinal tensile strength of the separator is 2700 kg / cm 2 or more.

[0040] In any embodiment of the present application, the transverse tensile strength of the separator is 2500 kg / cm 2 or more.

[0041] In any embodiment of the present application, the wetting length of the separator is 20 mm to 100 mm, and optionally, it is 40 mm to 70 mm.

[0042] The second aspect of the present application is a method for manufacturing the separator according to the first aspect of the present application, including the step of providing a substrate, the step of mixing the first particles and the second particles in a solvent to prepare a coating slurry, the step of applying the coating slurry to at least one side of the substrate to form a slurry film, drying the slurry film to form a coating, and obtaining a separator, where the first particles are organic particles, and when the average particle diameter of the first particles is D1 and the average particle diameter of the second particles is D2, 1 < D1 / D2 ≤ 10, a manufacturing method is provided.

[0043] The third aspect of the present application provides a secondary battery including the separator according to the first aspect of the present application or the separator obtained by the manufacturing method according to the second aspect of the present application.

[0044] The fourth aspect of the present application provides a power consumption device including the secondary battery according to the third aspect of the present application.

Brief Description of the Drawings

[0045] In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings that need to be used in the embodiments of the present application will be briefly described below. However, the drawings described below are only some embodiments of the present application, and it is obvious to those skilled in the art that other drawings can be obtained based on the drawings without any creative efforts. [Figure 1] 1 is a schematic diagram of an embodiment of a secondary battery of the present application. [Figure 2] FIG. 2 is an exploded schematic view of the embodiment of the secondary battery of FIG. [Figure 3] 1 is a schematic diagram of an embodiment of a battery module of the present application. [Figure 4] 1 is a schematic diagram of an embodiment of a battery pack of the present application. [Figure 5] 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 a power consuming device that includes a secondary battery of the present application as a power source, and the drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0046] Hereinafter, embodiments of a separator and a manufacturing method thereof, a secondary battery, and an electric power-using device that specifically disclose the present invention will be described in detail with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed descriptions of already known matters or redundant descriptions of the same actual configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Furthermore, 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.

[0047] The "ranges" disclosed herein are defined in terms of lower and upper limits, and a particular range is defined by selecting a lower and upper limit that define the boundaries of that particular range. Such defined ranges may or may not include the endpoints and may be arbitrarily combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it should be understood that the ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed and maximum range values of 3, 4, and 5 are listed, then all of the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are contemplated. In this application, unless otherwise specified, the numerical range "a to b" represents a shorthand notation for any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed herein, and "0-5" is merely a shorthand notation for combinations of these numbers. Also, describing a parameter as an integer greater than or equal to 2 is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise specified, all and any embodiments of the present application can be combined with each other to form a new technical solution, and such technical solution should be considered to be included in the disclosure of the present application.

[0049] Unless otherwise specified, all technical features and any technical features of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0050] Unless otherwise specified, all steps herein can be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b). This means that the method can include steps (a) and (b) performed sequentially, or can include steps (b) and (a) performed sequentially. For example, if it is stated that the method may include step (c), it means that step (c) can be added to the method in any order. 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.

[0051] Unless otherwise specified, the terms "comprise" and "contain" in this application are intended to represent open expressions, but may also be closed expressions. For example, the terms "comprise" and "contain" may mean that other elements not listed are also included or contained, or that only the listed elements are included or contained.

[0052] Unless otherwise specified, 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, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0053] In this application, terms such as "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0054] As used herein, the terms "plurality" and "plurality" refer to two or more than two.

[0055] Unless otherwise specified, terms used in this application have their commonly understood meanings as commonly understood by those of ordinary skill in the art.

[0056] Unless otherwise specified, the values of each parameter referred to in this application can be measured using various test methods commonly used in the art, for example, according to the test methods provided in the embodiments of this application.

[0057] 2. Description of the Related Art Secondary batteries have excellent electrochemical properties and safety features, and are therefore widely used in power-consuming devices such as power tools, electric transportation tools, and energy storage devices.

[0058] As secondary batteries become more widespread and more widely used, their performance requirements are becoming increasingly stringent. Two key areas of focus are the thermal safety and cycle performance of secondary batteries. A typical 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 located between the positive electrode plate and the negative electrode plate. Its primary role is to prevent short circuits between the positive and negative electrodes and to allow active ions to pass freely through the separator to form a circuit. Therefore, the separator is an important component for improving the thermal safety and cycle performance of a battery.

[0059] Currently, separator substrates are typically polyolefin films, which undergo significant thermal contraction when exposed to heat, potentially causing short circuits between the positive and negative electrodes of secondary batteries and affecting their thermal safety and cycle performance. Therefore, there is an urgent need to improve the thermal safety and cycle performance of secondary batteries.

[0060] In view of the above, 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 good wetting and liquid retention properties for the electrolyte, thereby providing the secondary battery with excellent thermal safety and cycle characteristics. Separator

[0061] A first aspect of an embodiment of the present application provides a separator including a substrate and a coating provided on at least one side of the substrate, the coating including first particles and second particles, the first particles being organic particles, where if the average particle diameter of the first particles is D1 and the average particle diameter of the second particles is D2, then 1 < D1 / D2 ≤ 10.

[0062] In the separator according to the present application, since the first particles are organic particles and the coating satisfies the above relationship, the first particles and the second particles are better overlapped in the coating. When the substrate shrinks due to heat, the organic particles have excellent heat resistance, and the organic particles, the second particles, and / or the organic particles and the second particles quickly push against each other to apply a force opposite to the shrinking direction to the substrate, thereby improving the thermal safety of the secondary battery. Further, when the second particles are filled between the first particles, many voids are generated in the coating, and the wetting effect of the electrolyte on the separator is further improved, which is advantageous for promoting the conduction of ions in the separator and improving the cycle characteristics of the secondary battery.

[0063] In the present application, the average particle diameter of a material has the meaning known in the art and can be measured using devices and methods known in the art. For example, a material or a separator is measured with a scanning electron microscope, a transmission electron microscope, a particle size distribution meter, etc., an image is obtained, and a plurality (for example, 100 or more) of test particles (for example, the first particles and the second particles of the present application) are randomly selected from the image, and the average value of the shortest diagonal length of the particles is calculated as the average particle diameter.

[0064] In some embodiments of the present application, the coating satisfies 2≦D1 / D2≦8, and optionally 3≦D1 / D2≦7. When the average particle size D1 of the first particles and the average particle size of the second particles satisfy the above relationship, the particles can be more effectively overlapped with each other, and when the substrate shrinks due to heat, the particles can be in efficient contact with and pressed against each other to apply a force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and increasing the deformation resistance of the substrate, thereby reducing the probability of short-circuiting between the positive and negative electrodes of the secondary battery and further improving the thermal safety of the secondary battery.

[0065] In some embodiments of the present application, the average particle diameter D1 of the first particles is 0.02 μm to 3.0 μm, and optionally 0.5 μm to 2 μm. Having the average particle diameter D1 of the first particles within the above appropriate range is advantageous for the electrolyte to wet the separator and provide the secondary battery with improved cycle characteristics. It also contributes to particle overlap. Furthermore, when the separator is subjected to heat, a force opposite to the direction of heat application is applied in a timely manner, thereby reducing the degree of shrinkage of the separator when subjected to heat and improving the thermal safety of the secondary battery. For example, the average particle diameter D1 of the first particles may be, but is not limited to, 0.04 μm to 2.5 μm, 0.1 μm to 2.3 μm, 0.5 μm to 2 μm, 0.8 μm to 1.8 μm, 1.0 μm to 1.5 μm, or 1.2 μm to 1.4 μm.

[0066] In some embodiments, the average particle size D1 of the first particles is 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, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 3.9 μm, 4.0 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm The thickness may be, but is not limited to, 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, 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, and 3.0 μm.

[0067] In some embodiments of the present application, the volume distribution particle size of the first particles is 1 v90≦3.0 μm, and optionally, 0.1 μm≦D 1 The volume distribution particle diameter D of the first particles is 2.0 μm or less. 1 By having v90 within the above range, the bulk density can be improved, the coating thickness can be made appropriate, and the energy density of the secondary battery can be improved.

[0068] In some embodiments, the volume distribution particle diameter D1v90 of the first 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, The thickness may be, but is not limited to, 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, 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, and 3.0 μm.

[0069] In any embodiment of the present application, the volume distribution particle size of the first particles may be 1 v50≦2 μm, and optionally, 0.01 μm≦D 1 The volume distribution particle diameter D of the first particles is v50≦1.5 μm. 1 When v50 is in the above range, it can contribute to strengthening the intimate contact between the first particles, causing adjacent particles to overlap each other. When the substrate shrinks due to heat, the particles quickly contact and press against each other, applying an acting force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and improving the deformation resistance of the substrate. As a result, the probability of short-circuiting between the positive and negative electrodes of the secondary battery is reduced, and the thermal safety of the secondary battery is further improved.

[0070] In some instances, the volume distribution particle diameter D of the first particles 1V50 is available in 0.01μm, 0.02μm, 0.03μm, 0.04μm, 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, and 0.6μm. , 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 μm, 1.4 μm, 1.45 μm, 1.5 μm, but are not limited to these.

[0071] In some embodiments of the present application, the particle size distribution of the first particles is 1 v90-D 1 v10) / D 1 v50≦1.5, and optionally, 0.5≦D 1 v90-D 1 v10) / D 1 v50≦1.0. When the particle size distribution of the first particles satisfies the above range, the particle size distribution of the first particles becomes uniform, which is advantageous in that the first particles are uniformly dispersed in the coating, forming a coating with a uniform thickness. Furthermore, when the coating slurry is applied to the surface of the substrate, the risk of the first particles falling into the voids in the substrate is reduced, ensuring the breathability of the substrate. Since the first particles are primarily distributed in the coating, the heat resistance of the entire coating can be ensured.

[0072] As an example, (D 1 v90-D 1 v10) / D 1 v50 may be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or a range consisting of any two of the foregoing values.

[0073] In this application, the volume distribution particle size Dv90 of a material has the meaning known in the art, which means the particle size when the cumulative volume distribution percentage of the material reaches 90%, and can be measured using instruments and methods known in the art, for example, GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, which can be tested using a laser particle size analyzer (e.g., Master Size 3000).

[0074] In this application, the volume distribution particle size Dv50 of a material has the meaning known in the art, and represents the particle size when the cumulative volume distribution percentage of the material reaches 50%, and can be measured using instruments and methods known in the art, for example, GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, and can be tested using a laser particle size analyzer (e.g., Master Size 3000).

[0075] In this application, the volume distribution particle size Dv10 of a material has the meaning known in the art, and represents the particle size when the cumulative volume distribution percentage of the material reaches 10%, and can be measured using instruments and methods known in the art, for example, GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, which can be tested using a laser particle size analyzer (e.g., Master Size 3000).

[0076] In some embodiments of the present application, the specific surface area of the first particles is 3 m 2 / g or more, selectively, 10m 2 / g~100m 2 When the specific surface area of the first particles is in the above appropriate range, the contact area between the first particles and the electrolyte can be increased, which contributes to improving the wetting effect and liquid retention effect of the electrolyte on the separator.

[0077] In some examples, the specific surface area of the first particles is 3 m 2 / g, 3.5m 2 / g, 4m 2 / g, 4.5m 2 / g、5m 2 / g、5.5m 2 / g、6m 2 / g、6.5m 2 / g、7m 2 / g、7.5m 2 / g、8m 2 / g、8.5m 2 / g、9m 2 / g、9.5m 2 / g、10m 2 / g、10.5m 2 / g、11m 2 / g、11.5m 2 / g、12m 2 / g、12.5m 2 / g、13m 2 / g、13.5m 2 / g、14m 2 / g、14.5m 2 / g、15m 2 / g、15.5m 2 / g、16m 2 / g、16.5m 2 / g、17m 2 / g、17.5m 2 / g、18m 2 / g、19m 2 / g、20m 2 / g、21m 2 / g、22m 2 / g、23m 2 / g、24m 2 / g、25m 2 / g、26m 2 / g、27m 2 / g、28m 2 / g、29m 2 / g、30m 2 / g、31m 2 / g、32m 2 / g、33m 2 / g、34m 2 / g、35m 2 / g、36m 2 / g、37m 2 / g、38m 2 / g、39m 2 / g、40m 2 / g、41m 2 / g、42m 2 / g、43m2 / g, 44m 2 / g, 45m 2 / g, 46m 2 / g, 47m 2 / g, 48m 2 / g, 49m 2 / g, 50m 2 / g, 55m 2 / g, 60m 2 / g, 65m 2 / g, 70m 2 / g, 75m 2 / g, 80m 2 / g, 85m 2 / g, 90m 2 / g, 95m 2 / g, 100m 2 / g, but is not limited thereto.

[0078] In an embodiment of the present application, when the weight of the first particles and the weight of the second particles in the coating satisfy an appropriate ratio, not only can the degree of shrinkage of the separator be reduced and the thermal safety of the secondary battery be improved, but the first particles can overlap more to form more voids, thereby further improving the wetting effect of the electrolyte and improving the cycle characteristics of the secondary battery.

[0079] In some embodiments of the present application, where the weight fraction of the first particles in the coating is A and the weight fraction of the second particles in the coating is B, the coating may be

[0080] In some embodiments of the present application, where A is the weight fraction of the first particles in the coating and B is the weight fraction of the second particles in the coating, the coating satisfies 50%≦A, optionally 70%≦A≦90%, and / or the coating satisfies B≦35%, optionally 15%≦B≦25%.

[0081] ​In some embodiments herein, the first particles include at least one of one or more of organosilicone resin 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.

[0082] In some embodiments of the present application, the first particles comprise organic silicone resin particles. The organic silicone resin particles refer to an organic siloxane whose main chain has a silicon-oxygen-silicon bond (-Si-O-Si-). Because the silicon-oxygen-silicon bond is an inorganic bond, it has a large bond energy, which can impart high heat resistance and chemical stability to the silicone. For example, the silicone can be used for long periods at temperatures below 200°C. The side chains of the silicone may be ungrafted or may have an organic group grafted thereto. The grafting of an organic group can impart good dispersibility to the silicone, improving the application properties of the silicone coating and its affinity with the substrate. Dispersion of the organic silicone resin particles in the coating provides the separator with excellent heat resistance, thereby improving the thermal safety of the secondary battery. Furthermore, a structure with voids between the organic silicone resin particles is formed, which improves the wetting and retention properties of the electrolyte solution in the separator and promotes the conduction of active ions in the separator. Therefore, when the separator is used in a secondary battery, the cycle characteristics of the secondary battery can be improved.

[0083] In some embodiments of the present application, the first particles comprise organosilicone resin particles, the organosilicone resin particles comprise a first polymer, and the first polymer comprises a first structural unit, a second structural unit, and a third structural unit.

[0084] The first structural unit has a structure represented by formula (I). Formula (I) [ka] (In formula (I), R1 comprises a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R1 is one or more selected from a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl; R2 includes substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C1-C20 hydroxyalkyl, and optionally R2 is one or more selected from C1-C12 alkyl, C3-C12 cycloalkyl, and C1-C12 hydroxyalkyl.

[0085] The second structural unit is represented by formula (II). Formula (II) [ka] (In formula (II), R3 includes a hydrogen atom or a substituted or unsubstituted C1 to C5 alkyl, and optionally R3 is one or more selected from a hydrogen atom or a substituted or unsubstituted C1 to C3 alkyl.)

[0086] The third structural unit is represented by formula (III). Formula (III) [ka] (In formula (III), R4 to R 11 are independently one or more selected from substituted or unsubstituted C1 to C10 alkyl or structural units represented by formula (III-1), wherein R4 to R 11 At least one of the structural units is represented by formula (III-1), Formula (III-1) [ka] (In formula (III-1), R 12contains a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R 12 is one or more selected from a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl, and R 13 is selected from substituted or unsubstituted C1-C10 alkyl, and optionally, R 13 is selected from substituted or unsubstituted C3 to C10 alkyl.

[0087] In these above-described embodiments, the soft monomer segment in the molecular segment of the first structural unit adjusts the glass transition temperature of the first polymer, improves the toughness and peel strength of the first polymer, and contributes to the development of good adhesive properties. The second structural unit can impart excellent swelling resistance and high adhesive properties, and also contributes to the improvement of the ionic conductivity of the secondary battery. The polysilsesquioxane in the third structural unit can improve the heat resistance of the first polymer. Furthermore, the combination of the first structural unit and the third structural unit exerts a synergistic effect, thereby improving the adhesive properties and heat resistance of the first polymer. The combination of the first structural unit and the second structural unit exerts a synergistic effect, thereby improving the thermal stability, swelling resistance, and the like of the first polymer. Therefore, the first polymer can further improve the heat resistance of the separator and the thermal safety of the secondary battery.

[0088] In some embodiments of the present application, the molar content of the first structural unit is 65≦a≦95, where a% is the molar content of the first structural unit based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit. When the molar content of the first structural unit is within this range, the adhesiveness of the first polymer can be improved. When the first polymer is used in a separator, the bonding strength between the first polymer and the separator substrate is significantly improved. Optionally, 70≦a≦90. For example, the molar content of the first structural unit may be 65%, 70%, 75%, 80%, 85%, 90%, or a range consisting of any two of the above values.

[0089] 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, when the molar content of the second structural unit is b%, then 0 < b ≤ 15. When the molar content of the second structural unit is within the above range, the thermal stability of the first polymer can be significantly improved. Optionally, 5 ≤ b ≤ 10. As an example, the molar content of the second structural unit may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or a range consisting of any two of the above numerical values.

[0090] 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, when the molar content of the third structural unit is c%, then 0 < c ≤ 10. When the molar content of the third structural unit is within the above range, the heat resistance of the first polymer can be further improved. Optionally, 5 ≤ c ≤ 9. As an example, the molar content of the third structural unit may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two of the above numerical values.

[0091] The cyano groups in the first structural unit and the second structural unit play a synergistic effect, jointly improving the swelling resistance and adhesiveness of the first polymer, enhancing the bonding force of the coating to the substrate and the deformation resistance, and further improving the thermal stability of the separator. Therefore, when the molar content a of the first structural unit and the molar content b of the second structural unit further satisfy 7 ≤ a / b ≤ 14, the synergistic effect of the first structural unit and the second structural unit can be further exerted, and the adhesiveness, stability, and swelling resistance of the first polymer can be improved. As an example, a / b may be 7, 8, 9, 10, 11, 12, 13, 14, or a range consisting of any two of the above numerical values.

[0092] In secondary batteries, the polysilsesquioxane in the third structural unit acts synergistically with the first structural unit to improve the heat resistance and adhesiveness of the entire first polymer, thereby improving the heat resistance of the separator and thereby improving the thermal safety of the secondary battery. Therefore, when the molar content a of the first structural unit and the molar content b of the second structural unit further satisfy the relationship 8≦a / c≦16, the synergistic effect of the first structural unit and the third structural unit is further exerted, improving the adhesiveness and heat resistance of the first polymer. For example, a / c may be 8, 9, 10, 11, 12, 13, 14, 15, 16, or a range consisting of any two of the above values.

[0093] 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 ratio a:b:c=(13-15):(2-4):(2-4). When the degrees of polymerization of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratio, these three structural units exert a synergistic effect, jointly improving the adhesion, swelling resistance, and heat resistance of the polymer.

[0094] The first structural unit includes a plurality of chemical structures, and specific chemical structures of the first structural unit will be described below.

[0095] In some embodiments of the present application, R1 is selected from a hydrogen atom and / or methyl.

[0096] In some embodiments of the present application, R2 comprises one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, isooctyl, 2-ethylhexyl, dodecyl, or isobornyl.

[0097] As an example, the first structural unit includes one or more of the structures represented by formulae (I-1) to (I-8). Formula (I-1) [ka] , formula (I-2) [ka] , formula (I-3) [ka] , formula (I-4) [ka] , formula (I-5) [ka] , formula (I-6) [ka] , formula (I-7) [ka] , formula (I-8) [ka]

[0098] The second structural unit includes a plurality of chemical structures, and specific chemical structures of the second structural unit will be described below.

[0099] In some embodiments of the present application, R3 comprises one or more of a hydrogen atom or methyl.

[0100] As an example, the second structural unit includes one or more of the structures represented by formulae (II-1) to (II-4). Formula (II-1) [ka] , formula (II-2) [ka] , formula (II-3) [ka] , formula (II-4) [ka]

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

[0102] In some embodiments of the present application, R4 to R 11 are each independently selected from the structural units represented by formula (III-1), and optionally, R 12 contains one or more of a hydrogen atom, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl or n-pentyl, and / or R 13 includes one or more of n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, isooctyl or 2-ethylhexyl.

[0103] In some embodiments, R4 to R 11 is selected from the structural units represented by formula (III-1), and optionally, R 12 contains a hydrogen atom, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl or n-pentyl, and / or R 13 is one or more selected from n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, isooctyl, and 2-ethylhexyl.

[0104] In the present application, the type of group in the first polymer can be measured using infrared spectroscopy. For example, the infrared spectrum of the material can be examined to determine the characteristic peaks contained in the material, thereby determining the type of modifying group. Specifically, infrared spectroscopy can be performed on the material using equipment and methods known in the art. For example, testing can be performed using an infrared spectrometer (e.g., an IS10 Fourier transform infrared spectrometer from Nicolet, USA) in accordance with the general rules of GB / T 6040-2019 infrared spectroscopy.

[0105] In some embodiments of the present application, the infrared spectrum of the first polymer contains a peak at 1750 cm indicative of the presence of an ester group. -1 ~1735cm -1 There is a characteristic peak.

[0106] In some embodiments of the present application, the infrared spectrum of the first polymer contains a peak at 2260 cm indicative of the presence of cyano. -1 ~2220cm -1 There is a characteristic peak.

[0107] In some embodiments of the present application, the infrared spectrum of the first polymer contains a 1100 nm peak, which indicates the presence of a Si—O—Si backbone of a silsesquioxane. -1 ~1120cm -1 There is a characteristic peak.

[0108] In some embodiments of the present application, the first polymer can be produced by a method comprising the following steps:

[0109] Step S100: Provide a first monomer, a second monomer, and a third monomer.

[0110] Step S200: The first monomer, the second monomer, and the third monomer are mixed together, and a polymerization reaction is caused by the action of an initiator to generate a first polymer.

[0111] In the present application, the first polymer formed by mixing and copolymerizing a first monomer, a second monomer, and a third monomer is a copolymer of three types of monomers.

[0112] The first monomer has the structure shown in formula (IV). Formula (IV) [ka] (In formula (IV), R1 comprises a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R1 is one or more selected from a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl; R2 includes substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C1-C20 hydroxyalkyl, and optionally R2 is one or more selected from C1-C12 alkyl, C3-C12 cycloalkyl, and C1-C12 hydroxyalkyl.

[0113] The first monomer is an acrylate-based compound, and upon polymerization, the carbon-carbon double bond is opened to form the first structural unit.

[0114] As an example, the first monomer may include one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, s-butyl acrylate, t-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.

[0115] The second monomer has the structure shown in formula (V). Formula (V) [ka] (In formula (V), R3 includes a hydrogen atom or a substituted or unsubstituted C1 to C5 alkyl, and optionally R3 is one or more selected from a hydrogen atom or a substituted or unsubstituted C1 to C3 alkyl.)

[0116] The second monomer is an acrylonitrile-based compound, and upon polymerization, the carbon-carbon double bond is opened to form a second structural unit.

[0117] In one example, the second monomer includes acrylonitrile and / or methyl acrylonitrile.

[0118] The third monomer has the structure shown in formula (VI). Formula (VI) [ka] (In formula (VI), R 30 ~R 37 are independently one or more selected from substituted or unsubstituted C1 to C10 alkyl or structural units represented by formula (VI-1), wherein R 30 ~R 37 at least one of which is a structural unit represented by formula (VI-1), Formula (VI-1) [ka] (In formula (VI-1), R 12 contains a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R 12 is one or more selected from a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl, R 13is selected from substituted or unsubstituted C1-C10 alkyl, and optionally, R 13 is selected from substituted or unsubstituted C3 to C10 alkyl.

[0119] As an example, the third monomer includes one or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacryloyloxypropylheptaisobutylpolysilsesquioxane, methacryloyloxypropylheptaoctylpolysilsesquioxane, acryloyloxypropyl cage-type polysilsesquioxane, acryloyloxypropylheptaisobutylpolysilsesquioxane, and methacryloyloxypropylheptaoctylpolysilsesquioxane.

[0120] In some embodiments of the present application, step S200 specifically includes the following steps: Step S210: The first monomer, the second monomer, and the third monomer are added to the solvent and the emulsifier, and mixed to form a mixed system. Step S220: An initiator is added to the mixture, and a polymerization reaction is carried out by the action of the initiator to produce a first polymer.

[0121] In the present invention, multiple monomers can be copolymerized by emulsion polymerization, which is a simpler polymerization method. Of course, other polymerization methods such as solution polymerization and suspension polymerization can also be used in the present invention. The process parameters used in the polymerization process can be selected from parameters commonly used in the art, and will not be described in detail here.

[0122] In some embodiments of the present application, the emulsifier comprises one or more of sodium lauryl sulfate, sodium dodecylbenzene sulfonate, alkyldiphenyloxide disulfonate, ethoxylated alkylphenol ammonium sulfate.

[0123] In some embodiments of the present application, the ratio of the mass percentage content of the emulsifier to the mass percentage contents of the first, second, and third monomers is 0.1% to 5% based on the total mass of the mixed system, i.e., the amount of emulsifier used is 0.1% to 5% of the mass of the three monomers. When the mass percentage content of the emulsifier is within this range, the first, second, and third monomer emulsions can be dispersed in a solvent to form a uniform system.

[0124] In some embodiments of the present application, the initiator comprises potassium persulfate and / or ammonium persulfate.

[0125] In some embodiments of the present application, the ratio of the mass percentage content of the initiator to the mass percentage content of the second monomer, the second monomer, and the third monomer is 0.15% to 1% based on the total mass of the mixed system, i.e., the amount of initiator used is 0.1% to 5% of the mass of the three monomers. When the mass percentage content of the initiator is in the above range, sufficient polymerization is ensured.

[0126] In some embodiments of the present application, the solvent may include water, for example, deionized water.

[0127] In one specific embodiment, the method includes:

[0128] Preparation of prepolymer: Deionized water, an emulsifier, a first polymerizable monomer, a second polymerizable monomer, and a third polymerizable monomer are blended and stirred uniformly to obtain a prepolymer.

[0129] Preparation of the first polymer: Add the emulsifier and deionized water to a vessel and emulsify for 30-60 minutes to obtain a uniform, stable emulsion. Then, slowly add the prepolymer and initiator solution (a solution of potassium persulfate and / or ammonium persulfate in deionized water) 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 allow the reaction to proceed. The mixture is then cooled to 40°C, the pH is adjusted to 7-8 with aqueous ammonia, the material is filtered, and the resulting mixture is dried to obtain the polymer.

[0130] In some embodiments of the present application, the second particles comprise organosilicone resin particles, and the organosilicone resin particles further comprise a second polymer, and the second polymer comprises a structural unit represented by formula (a). Formula (a) [ka] (In formula (a), R 14 and R 15 each independently comprises one or more of substituted or unsubstituted C1-C10 alkyl, hydroxy, or amino. 14 and R 15 each independently includes one or more of substituted or unsubstituted C1-C6 alkyl, hydroxy, or amino.

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

[0132] As an example, the organic silicone resin particles contain at least one of the structures represented by formulas (a-1) to (a-5). Formula (a-1) [ka] , formula (a-2) [ka] , formula (a-3) [ka] , formula (a-4) [ka] , formula (a-5) [ka]

[0133] The terms "first polymer" and "second polymer" in this application are used only to distinguish types of materials and do not serve to limit the order or quantity.

[0134] In some embodiments of the present application, the number-average molecular weight of the organic silicone resin particles is 30,000 to 70,000, optionally 40,000 to 50,000. For example, the number-average molecular weight of the organic silicone resin particles may be 30,000, 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 organic silicone resin particles is within the above range, the organic silicone resin particles have high viscosity, and their use in separators is advantageous for increasing the adhesion between the separator and positive and negative electrodes. On the other hand, it is advantageous to form organic silicone resin particles with small particle diameters, and their use in separators allows for a thin coating on the separator, reducing the overall thickness of the separator and facilitating an improvement in the energy density of secondary batteries. Furthermore, the particle size of the organic silicone resin particles is not too small, which reduces the risk of the organic silicone resin particles clogging the separator substrate, and can improve the properties of the separator as a whole, such as its air permeability.

[0135] In the present application, the number average molecular weight of the first polymer can be tested by gel permeation chromatography (GPC). Specifically, using a GPC1515 apparatus manufactured by American Waters Company, a sample is dissolved in tetrahydrofuran for 12 hours or more to a concentration of 4 mg / mL, and the sample is filtered to obtain a sample, which is then tested at a test temperature of 25°C and a test flow rate of 1 mL / min.

[0136] After further investigation, the inventors discovered that during the long-term charge / discharge cycle of a secondary battery, moisture in the separator gradually releases and penetrates into the electrolyte. The electrolyte is highly sensitive to moisture and is prone to generating hydrofluoric acid (HF) upon contact with water, which increases the acidity of the electrolyte, causing corrosion of the active material and current collector, and potentially leading to the elution of transition metal ions in the active material, which may affect the electrochemical characteristics of the secondary battery. Therefore, in the present application, the water content of the organic silicone resin particles is adjusted to 3000 μg / g or less, or optionally 600 μg / g to 2800 μg / g, based on the mass of the organic silicone resin particles. When the water content of the organic silicone resin particles is within the above range, the organic silicone resin particles contain a low amount of water, reducing the risk of side reactions in the electrolyte during long-term charge / discharge cycles of the secondary battery and improving the electrochemical characteristics of the secondary battery. As an example, the moisture content of the organic silicone resin particles may be 600 μg / g, 800 μg / g, 1000 μg / g, 1200 μg / g, 1500 μg / g, 1800 μg / g, 2000 μg / g, 2500 μg / g, 2800 μg / g, or a range consisting of any two of the above values.

[0137] In the present application, the moisture content of the organic silicone resin particles can be measured using a moisture meter. The test method is the Karl Fischer moisture measurement method, and the test equipment used is the Swiss company Metrohm's Model 831 Karl Fischer moisture meter.

[0138] In some embodiments of the present application, the average particle diameter D2 of the second particles is 0.01 μm to 2 μm, and optionally 0.1 μm≦D2≦1 μm. When the average particle diameter D2 of the second particles is in the above appropriate range, it is advantageous for the electrolyte to wet the separator and improve the cycle characteristics of the secondary battery, and also contributes to particle overlap. Furthermore, when the separator is subjected to heat, an acting force in the opposite direction to the direction in which the separator is subjected to heat is applied in a timely manner, thereby reducing the degree of shrinkage of the separator when subjected to heat and improving the thermal safety of the secondary battery.

[0139] In some examples, the average particle size D2 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, 1.2 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 numerical values, but is not limited to these.

[0140] In some embodiments of the present application, the volume distribution particle size of the second particles is 2 v90≦2 μm, and optionally, 0.3 μm≦D 2 The volume distribution particle diameter D of the second particle is v90≦1.5 μm. 2 By having v90 within the above range, the second particles can be filled between the organic silicone resin particles, thereby strengthening the contact between the particles.

[0141] In some instances, the volume distribution particle diameter D of the second particles 2V90 is available in the following sizes: 0.01μm, 0.02μm, 0.03μm, 0.04μm, 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, 0.6μm, 0.65μm, 0.7μm, 0.75μm, 0.80μm, 0.85μm, 0.9μm, 0. The thickness may be, but is not limited to, 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 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 numerical values.

[0142] In some embodiments of the present application, the volume distribution particle size of the second particles is 2 v50≦1.5 μm, and optionally 0.2 μm≦D 2 v50≦1 μm. Volume distribution particle diameter D of the second particle 2 By having v50 in the above range, the organic silicone resin particles can be intimately contacted with each other, and adjacent particles can overlap each other. When the substrate shrinks due to heat, the particles can quickly contact and press against each other, providing a force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and improving the deformation resistance of the substrate. This reduces the probability of short-circuiting between the positive and negative electrodes of the secondary battery, and further improves the thermal safety of the secondary battery.

[0143] In some instances, the volume distribution particle diameter D of the second particles 2V50 is available in 0.01μm, 0.02μm, 0.03μm, 0.04μm, 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, 0.6μm, 0.65μm, 0. The thickness may be, but is not limited to, 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 μm, 1.4 μm, 1.45 μm, 1.5 μm, or a range consisting of any two of the above values.

[0144] In some embodiments of the present application, the specific surface area of the second particles is 10 m 2 When the specific surface area of the second particles is in the above-described appropriate range, the contact area between the second particles and the electrolyte can be increased, which contributes to improving the wetting effect and liquid retention effect of the electrolyte on the separator.

[0145] In some embodiments of the present application, the particle size distribution of the second particles is: (D 2 v90-D 2 v10) / D 2 v50≦1.0, and optionally 0.2≦(D 2 v90-D 2 v10) / D 2 v50≦0.8. When the particle size distribution of the second particles is in the above range, the particles are more likely to overlap with each other during coating, and when the substrate shrinks due to heat, the particles quickly come into contact with each other and press against each other, applying a force opposite to the direction of shrinkage of the substrate, further reducing the degree of shrinkage of the substrate and improving the heat resistance of the separator.

[0146] In some examples, the specific surface area of the second particles is greater than 10 m 2 / g, 10.5m 2 / g, 11m 2 / g, 11.5m 2 / g, 12m 2 / g, 12.5m 2 / g, 13m2 / g、13.5m 2 / g、14m 2 / g、14.5m 2 / g、15m 2 / g、15.5m 2 / g、16m 2 / g、16.5m 2 / g、17m 2 / g、17.5m 2 / g、18m 2 / g、19m 2 / g、20m 2 / g、21m 2 / g、22m 2 / g、23m 2 / g、24m 2 / g、25m 2 / g、26m 2 / g、27m 2 / g、28m 2 / g、29m 2 / g、30m 2 / g、31m 2 / g、32m 2 / g、33m 2 / g、34m 2 / g、35m 2 / g、36m 2 / g、37m 2 / g、38m 2 / g、39m 2 / g、40m 2 / g、41m 2 / g、42m 2 / g、43m 2 / g、44m 2 / g、45m 2 / g、46m 2 / g、47m 2 / g、48m 2 / g、49m 2 / g、50m 2 / g、55m 2 / g、60m 2 / g、65m 2 / g、70m 2 / g、75m 2 / g、80m 2 / g、85m 2 / g、90m 2 / g、95m 2 / g、100m2 / g, or a range consisting of any two of the above values, but is not limited thereto.

[0147] In some embodiments herein, the second particles include one or more of inorganic particles, polymeric particles.

[0148] As an example, the inorganic particles include one or more selected from inorganic particles having a dielectric constant of 5 or greater, inorganic particles capable of conducting active ions, and inorganic particles capable of undergoing electrochemical oxidation and reduction.

[0149] Optionally, the inorganic particles having a dielectric constant of 5 or more include boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, magnesium lithium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 <m<1、0<n<1)、Pb(Mg3Nb 2 / 3)O3-PbTiO3 (abbreviated as PMN-PT), and one or more of these modified inorganic particles. Optionally, the inorganic particles may be modified chemically and / or physically. Chemical modification methods include coupling agent modification (e.g., silane coupling agents, titanate coupling agents, etc.), surfactant modification, polymer graft modification, etc. Physical modification methods may include mechanical dispersion, ultrasonic dispersion, high-energy treatment, etc. The modification treatment can reduce the aggregation of inorganic particles. Furthermore, modifying the inorganic particles with coupling agents or surfactants having specific functional groups can improve the wetting properties of the coating with the electrolyte and increase the adhesion of the coating.

[0150] Alternatively, inorganic particles that are ionically conductive but do not store ions include Li3PO4, lithium titanium phosphate, Li x1 Ti y1 (PO4)3, Lithium Titanium Aluminum Phosphate Li x2 Al y2 Ti z1 (PO4)3, (LiAlTiP) x3 O y3 Glass, Lithium lanthanum titanate x4 La y4 TiO3, Lithium germanium thiophosphate Li x5 Ge y5 P z2 S w , lithium nitride Li x6 N y6 , SiS2 type glass Li x7 Si y7 S z3 , and P2S5 type glass Li x8 P y8 S z4including one or more of the following, where 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. Thereby, the ion conduction characteristics of the separator can be further improved.

[0151] Optionally, the inorganic particles capable of undergoing an electrochemical reaction include at least one of a lithium-containing transition metal oxide, a lithium-containing phosphate, a carbon-based material, a silicon-based material, a tin-based material, and a lithium titanium compound.

[0152] Optionally, the polymer particles include one or more of organosilicon resin particles, melamine formaldehyde resin particles, phenol resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramide particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles. The organosilicon resin particles contained in the polymer particles are the same as the organosilicon resin particles contained in the first particles.

[0153] In some embodiments of the present application, the thickness of the coating is 0.1 μm to 5 μm, optionally 0.5 μm to 3 μm. When the thickness of the coating is within the above range, the degree of dense packing of the particles in the coating is improved, which further contributes to improving the thermal safety of the secondary battery.

[0154] In some embodiments of the present application, the porosity of the coating is 20% or more, optionally 25% to 50%. When the coating contains organosilicon resin particles, when the porosity of the coating is within the above range, the wetting effect and liquid retention effect of the electrolyte on the separator can be further improved, which is advantageous for ion conduction in the separator and improves the cycle characteristics of the secondary battery.

[0155] In some embodiments of the present application, the thickness of the substrate is 16 μm or less, optionally 3 μm to 9 μm. The coating of the present application improves the thermal stability and cycling characteristics of the separator, thereby enabling the use of thinner substrates and contributing to further improvements in the energy density of secondary batteries.

[0156] In some embodiments of the present application, the substrate has a porous structure and a porosity of 20% or more. Optionally, the porosity of the substrate is 25% to 50%. When the porosity of the porous substrate is within the above appropriate range, it is advantageous for further improving the ion conductivity of the separator and improving the cycle characteristics of the secondary battery.

[0157] In the present application, the material of the substrate is not particularly limited, and any known substrate having good chemical and mechanical stability may be used. 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 thin film or a multi-layer composite thin film. When the porous substrate is a multi-layer composite thin film, the materials of the layers may be the same or different.

[0158] In some embodiments of the present application, the separator has a thermal shrinkage rate of 3% or less in the longitudinal direction at 150°C for 1 hour.

[0159] In some embodiments of the present application, the separator has a thermal shrinkage rate of 2% or less in the transverse direction at 150° C. for 1 hour.

[0160] In these above-mentioned 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 of the secondary battery.

[0161] In some embodiments of the present application, the separator has an air permeability of 200 s / 100 mL or less. Optionally, the separator has an air permeability of 150 s / 100 mL to 200 s / 100 mL. The separator of the present application has good air permeability, which can enhance ion conduction characteristics and reduce the resistance of the secondary battery, thereby improving the cycle characteristics of the secondary battery.

[0162] In some embodiments of the present application, the separator has a longitudinal tensile strength of 2700 kg / cm 2 That's all.

[0163] In some embodiments of the present application, the separator has a transverse tensile strength of 2500 kg / cm 2 That's all.

[0164] In these above-described embodiments, the separator of the present application has high tensile strength in both the transverse and longitudinal directions, which reduces the probability of separator breakage when the secondary battery expands, and can further improve the safety of the secondary battery.

[0165] 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, by testing them in accordance with standard GB / T 36363-2018.

[0166] In some embodiments of the present application, the separator has a wetted length of 20 mm to 100 mm, optionally 40 mm to 70 mm. The separator of the present application has excellent wettability with the electrolyte, which can improve the ion conduction characteristics and the capacity of the secondary battery.

[0167] In this application, the wetting length of the separator has the meaning known in the art and can be measured using methods known in the art. An exemplary test method is as follows. Cut the separator into samples with a width of 5 mm and a length of 100 mm, fix both ends of the sample, and place it horizontally. Drop 0.5 mg of electrolyte solution at the center of the sample, take a photo after 1 minute, measure the diffusion length of the electrolyte solution, and obtain the wetting length of the separator. To ensure the accuracy of the test results, collect a plurality (for example, 5 to 10) of samples for the test, and obtain the test results by calculating the average value. The electrolyte solution can be prepared by the following method. Mix ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, dissolve sufficiently dried LiPF6 in the above organic solvent, and prepare an electrolyte solution with a concentration of 1 mol / L.

[0168] Note that the coating parameters of the above separator are the coating parameters on one side of the substrate.

[0169] When the coating is provided on both sides of the substrate, as long as the coating parameters on either side meet the requirements of this application, it is considered to be within the protection scope of this application. Manufacturing method of separator

[0170] The second aspect of this application provides a method for manufacturing a separator, which includes step S1 of providing a substrate, step S2 of mixing the first particles and the second particles in a solvent to prepare a coating slurry, and step S3 of applying the coating slurry to at least one side of the substrate to form a slurry film, drying the slurry film to form a coating, and obtaining the separator. The first particles are organic particles. If the average particle diameter of the first particles is D1 and the average particle diameter of the second particles is D2, then 1 < D1 / D2 ≤ 10.

[0171] In some embodiments of the present application, the solvent in S2 may be water, for example, deionized water. The binder may be a water-soluble binder, which has the advantages of good thermodynamic stability and environmental protection, making it useful for preparing and applying the coating slurry. As an example, the water-soluble binder may include at least one of a water-soluble acrylic resin (e.g., a homopolymer of acrylic acid, methyl acrylic acid, or sodium acrylate monomer, or a copolymer with other comonomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer, and polyacrylamide. Furthermore, the coating slurry may include other components, such as a dispersant or a wetting agent.

[0172] In some embodiments of the present application, a coater is used for coating in S3. The type of coater is not particularly limited in the present application, and for example, a commercially available coater can be used. Optionally, the coater includes a gravure roller used to transfer the coating slurry to the substrate. Optionally, the gravure roller has a ruling of 150 LPI-250 LPI, or 180 LPI-200 LPI. Furthermore, the coating method can be transfer coating, spin spray coating, dip coating, or the like.

[0173] In some embodiments of the present application, the coating speed in S3 can be controlled to 40 m / min to 150 m / min, for example, 60 m / min to 100 m / min. When the coating speed is within the above range, problems with the coating film surface can be reduced, the probability of coating unevenness can be reduced, and the energy density and safety of the secondary battery can be improved.

[0174] By controlling each of the above process parameters within a predetermined range, the properties of the separator of the present application can be further improved. Those skilled in the art can selectively adjust one or more of the above process parameters according to the actual manufacturing conditions.

[0175] For parameters such as some of the raw materials used in the manufacturing method of the separator of the present application and their contents, please refer to the separator described in the first aspect of the embodiment of the present application, and they will not be described in detail here. Unless otherwise specified, each raw material used in the manufacturing method of the separator of the present application is commercially available. secondary battery

[0176] A third aspect of the present invention provides a secondary battery. A secondary battery, also known as a rechargeable battery or storage battery, refers to a battery that can be recharged after discharge to activate the active material and continue to be used. A secondary battery typically 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 primarily serves to prevent short circuits between the positive electrode and the negative electrode, while allowing active ions to pass through.

[0177] In the present application, the type of secondary battery is not particularly limited, and for example, the secondary battery may be a lithium ion battery, a sodium ion battery, or the like, and in particular may be a lithium ion secondary battery.

[0178] The secondary battery of the present application includes the separator according to the first aspect of the present application or the separator obtained by the manufacturing method according to the second aspect of the present application, the separator being interposed between a positive electrode plate and a negative electrode plate. Optionally, the coating of the present application is present at least on the side of the separator closest to the negative electrode plate. This allows the secondary battery of the present application to have excellent thermal safety and cycle characteristics. [Positive electrode plate]

[0179] In some embodiments of the present application, the positive electrode plate includes a positive electrode current collector and a positive electrode film provided 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 a positive electrode film is used on one or both of the two opposite sides of the positive electrode current collector.

[0180] When the secondary battery of the present application is a lithium-ion secondary battery, the positive electrode active material includes at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and modified compounds thereof. Examples of lithium-containing transition metal oxides include, but are not limited to, 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 at least one of modified compounds thereof. Examples of lithium-containing phosphates include, but are not limited to, 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 at least one of modified compounds thereof.

[0181] In some embodiments of the present application, in order to further improve the energy density of the secondary battery, the positive electrode active material for the lithium-ion secondary battery has a general formula of Li a Ni b Co c M d O e A f and may include at least one of lithium-containing transition metal oxides and modified compounds thereof. 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.

[0182] As an example, the positive electrode active material for the lithium-ion secondary battery is 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 contains at least one of O2, LiFePO4, and LiMnPO4.

[0183] 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 to these.

[0184] As an example, the positive electrode active material for a sodium ion secondary battery is 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 include, but is not limited to, at least one of the materials 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.

[0185] In the present application, the modified compounds of the above-mentioned positive electrode active materials are positive electrode active materials modified by doping and / or surface coating.

[0186] In some embodiments of the present application, the positive electrode film may optionally further include a positive electrode conductive agent. In the present application, the type of the positive electrode conductive agent is not particularly limited. For example, the positive 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 positive electrode conductive agent is 6 wt% or less, based on the total weight of the positive electrode film.

[0187] In some embodiments of the present application, the positive electrode film optionally further includes a positive electrode binder. The type of positive electrode binder is not particularly limited in the present application. For example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorinated acrylate resin. In some embodiments of the present application, the mass percentage content of the positive electrode binder is 5 wt% or less based on the total weight of the positive electrode film. In some embodiments of the present application, the positive electrode current collector may be a metal foil or a composite current collector. An example of a metal foil 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. By way of example, the metallic material may include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. By way of example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene terephthalate (PE).

[0188] The positive electrode film is typically produced by coating a positive electrode slurry on a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically produced by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and optional other components in a solvent and stirring the mixture until uniform. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). [Negative electrode plate]

[0189] In some embodiments of the present application, the negative electrode plate includes a negative electrode current collector and a negative electrode film provided 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 the thickness direction, and the negative electrode film is used on one or both of the two opposite sides of the negative electrode current collector.

[0190] 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, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy materials.

[0191] In some embodiments of the present application, the negative electrode film optionally further includes a negative electrode conductive agent. The type of the negative electrode conductive agent is not particularly limited in the present application. 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% or less, based on the total weight of the negative electrode film.

[0192] In some embodiments of the present application, the negative electrode film optionally further includes a negative electrode binder. The type of negative electrode binder is not particularly limited in the present application. For example, the negative electrode binder may include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic 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 binder is 6 wt% or less, based on the total weight of the negative electrode film.

[0193] In some embodiments of the present application, the negative electrode film may further include other additives. For example, the other additives may include a thickener, such as sodium carboxymethyl cellulose (CMC), a PTC thermistor material, etc. In some embodiments of the present application, the mass percentage content of the other additives is 3 wt % or less, based on the total weight of the negative electrode film.

[0194] In some embodiments of the present application, the negative electrode current collector may be a metal foil or a composite current collector. An example of the metal foil may be copper foil. The composite current collector may include a polymer base layer and a metal layer provided 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 terephthalate (PE).

[0195] The negative electrode film is typically produced by coating a negative electrode slurry onto a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically produced by dispersing the negative electrode active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring the resulting mixture to homogeneity. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0196] The negative electrode plate may have additional functional layers other than the negative electrode film. For example, in some embodiments, the negative electrode plate of the present application may further include a conductive primer (e.g., composed of a conductive agent and a binder) interposed between the negative electrode current collector and the negative electrode film and provided on the surface of the negative electrode current collector. In other embodiments, the negative electrode plate of the present application may further include a protective layer coated on the surface of the negative electrode film. [Electrolyte]

[0197] During the charge and discharge process of a secondary battery, active ions are repeatedly absorbed and released between the positive and negative electrodes, and the electrolyte serves to conduct the active ions between the positive and negative electrodes. In this application, the type of electrolyte is not particularly limited and can be selected according to actual needs.

[0198] The electrolyte solution includes an electrolyte salt and a solvent, and the types of the electrolyte salt and the solvent are not particularly limited and can be selected according to actual needs.

[0199] When the secondary battery of the present application is a lithium-ion secondary battery, the electrolyte salt may include, by way of example only, 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).

[0200] When the secondary battery of the present application is a sodium-ion secondary battery, the electrolyte salt may include, by way of example only, at least one of sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (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).

[0201] 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 ester (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), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0202] 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 capable of improving some characteristics of the secondary battery, such as an additive that improves the overcharge characteristics of the secondary battery, an additive that improves the high-temperature characteristics of the secondary battery, or an additive that improves the power characteristics of the secondary battery at low temperatures.

[0203] In some embodiments of the present application, the positive electrode plate, separator, and negative electrode plate may be formed into an electrode assembly by a winding and / or stacking process.

[0204] In some embodiments of the present application, the secondary battery may further include an exterior material, which is used to encapsulate the electrode assembly and the electrolyte solution.

[0205] In some embodiments of the present application, the exterior material of the secondary battery may be a hard housing, such as a hard plastic housing, an aluminum housing, or a steel housing. The exterior material of the secondary battery may be a soft bag, such as a pouch-shaped soft bag. The soft bag may be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0206] In the present application, the shape of the secondary battery is not particularly limited, and it may be cylindrical, rectangular, or any other shape. Figure 1 may be an example of a secondary battery 5 having a rectangular structure.

[0207] In some embodiments of the present application, as shown in FIG. 2 , the exterior material may include a shell 51 and a cover plate 53. The shell 51 includes a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate define a storage chamber. The shell 51 has an opening communicating with the storage chamber, and the cover plate 53 covers the opening to seal the storage chamber. The positive electrode plate, the negative electrode plate, and the separator are wound and / or stacked to form an electrode assembly 52. The electrode assembly 52 is sealed in the storage chamber. The electrolyte wets the electrode assembly 52. The secondary battery 5 may include one or more electrode assemblies 52, and this can be adjusted according to needs.

[0208] The method for manufacturing the secondary battery of the present application is well known. In some embodiments of the present application, a positive electrode plate, a separator, a negative electrode plate, and an electrolyte can be assembled into a secondary battery. For example, the positive electrode plate, the separator, and the negative electrode plate can be formed into an electrode assembly by a winding process and / or a stacking process, and the electrode assembly can be placed in a housing, baked, injected with an electrolyte, and subjected to processes such as vacuum sealing, standing, formation, and shaping to obtain a secondary battery.

[0209] In some embodiments of the present application, the secondary battery according to the present application may be assembled into a battery module, and the number of secondary batteries included in the battery module may be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0210] Fig. 3 is a schematic diagram of an example of a battery module. As shown in Fig. 3, in a battery module 4, a plurality of secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, they may be arranged in any other manner. The plurality of secondary batteries 5 may further be fastened together by fasteners.

[0211] Optionally, the battery module 4 may further include a housing having a storage space, and the plurality of secondary batteries 5 are stored in the storage space.

[0212] In some embodiments of the present application, the above battery modules may be 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.

[0213] 4 and 5 are schematic diagrams of an example of a 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 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 is covered by the lower housing 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner. power consumption equipment

[0214] A fourth aspect of the present embodiment provides a power consuming device including at least one of the secondary battery, battery module, or secondary battery pack according to the third aspect of the present application. The secondary battery, battery module, or battery pack can function as both a power source for the power consuming device and 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, an over-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.), a train, a ship, a satellite, an energy storage system, etc.

[0215] A power consuming device can choose a secondary battery, a battery module, or a battery pack according to its needs.

[0216] 6 is a schematic diagram of an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, in order to meet the need for high power output and high energy density of the power consuming device, a battery pack or battery module can be used.

[0217] Other examples of power consuming devices include mobile phones, over-the-top laptops, etc. Such power consuming devices usually require light weight and thinness, so they can use secondary batteries as their power source.

[0218] The following embodiments are intended to more fully illustrate the present disclosure and are for illustrative purposes only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise specified, all parts, percentages, and ratios reported in the following embodiments are by weight, all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all equipment used in the embodiments is commercially available. Example 1

[0219] Manufacturing of organic silicone resin particles

[0220] Preparation of prepolymer: 1400 g of deionized water and 7 g of sodium lauryl sulfate were added to a 5 L three-neck flask and emulsified at 1500 r / min for 30 min to obtain a uniform, stable emulsion. 645.68 g of methyl acrylate, 79.59 g of acrylonitrile, and 663.50 g of methacryloyloxypropyl cage-type polysilsesquioxane (the molar ratio of methyl acrylate, acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane was 15:3:2) were then added in that order and stirred at 1500 r / min for an additional 30 min to obtain a uniform prepolymer.

[0221] Polymer preparation: 3g of sodium lauryl sulfate and 1000g of deionized water were added to a dry three-neck flask and emulsified with high-speed stirring for 30 minutes to obtain a uniform and stable emulsion. Then, using a peristaltic pump, the prepolymer and initiator solution (3g of potassium persulfate dissolved in 30g of deionized water) prepared in the previous step were slowly added dropwise. After the addition was complete, the temperature was raised to 90°C and the reaction was allowed to proceed for 0.5 hours. The mixture was then cooled to 40°C, the pH was adjusted to 7-8 with aqueous ammonia, and the mixture was filtered, discharged, and dried to obtain organosilicone resin particles with a number average molecular weight of 43676, designated M1.

[0222] Here, the average particle diameter D1 of the organic silicone resin particles M1 is 1.5 μm, and the volume distribution particle diameter D 1 v90 is approximately 1.6 μm, D 1 v50 is approximately 1.3 μm, D 1 V10 is about 0.3 μm, specific surface area is about 30 m 2 / g. Separator manufacturing

[0223] PE substrate provided: thickness 4.5 μm, porosity 40%.

[0224] Preparation of coating slurry: Organic silicone resin particles M1, aluminum oxide particles, and binder polyacrylamide were mixed in a predetermined ratio (ratio h 5:1:1) with water to prepare a coating slurry. Here, the average particle diameter D2 of the aluminum oxide particles was 0.75 μm, and the volume distribution particle diameter D 1 v90 is approximately 0.8 μm, D 1 v50 is approximately 0.73 μm, D 1 V10 is approximately 0.2 μm, and the specific surface area is approximately 8 m 2 / g.

[0225] Coating: The prepared coating slurry was applied to both sides of the PE substrate using a coater, and after drying and slitting, a separator with a coating thickness of 4 μm and a coating porosity of 40% was obtained. Positive electrode plate manufacturing

[0226] LiNi as an active material 1 / 3 Mn 1 / 3 Co 1 / 3 O2 (NCM333), acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were uniformly mixed in a weight ratio of 94:3:3 with an appropriate amount of N-methylpyrrolidone (NMP) as a solvent to obtain a positive electrode slurry. The positive electrode slurry was applied to an aluminum foil positive electrode current collector, and then subjected to processes such as baking, cold pressing, slitting, and cutting to obtain a positive electrode plate. Negative electrode plate manufacturing

[0227] The negative electrode slurry was obtained by uniformly mixing artificial graphite as the negative electrode active material, carbon black (Super P) as the conductive agent, styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) as the binder in a mass ratio of 95:2:2:1 with an appropriate amount of deionized water as the solvent. The negative electrode slurry was applied to a copper foil negative electrode current collector, and then subjected to baking, cold pressing, slitting, and cutting processes to obtain a negative electrode plate. Electrolyte production

[0228] Ethylene carbonate (EC) and methyl ethyl 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. Secondary battery manufacturing

[0229] The positive electrode plate, separator, and negative electrode plate were stacked in this order and wound up to obtain an electrode assembly. The electrode assembly was placed in an outer casing, dried, and then an electrolyte was injected. The secondary battery was obtained through processes such as vacuum sealing, standing, formation, and shaping. Examples 2 to 10

[0230] Except for the relevant parameters of the separator and coating, the secondary battery was fabricated in the same manner as in Example 1, and the specific parameters are shown in Table 1. Comparative Example 1-2

[0231] Except for the relevant parameters of the separator coating, the secondary battery was fabricated in the same manner as in Example 1, and the specific parameters are shown in Table 1. Examples 11 to 14

[0232] Except for the mass contents of the first particles and the second particles contained in the separator coating, the secondary battery was fabricated in the same manner as in Example 4, and the specific parameters are shown in Table 2. Comparative Example 3

[0233] Except for the mass of the first particles and the second particles contained in the separator coating being different, the secondary battery was fabricated in the same manner as in Example 4, and the specific parameters are shown in Table 2. Testing section

[0234] (1) Separator heat shrinkage test

[0235] Sample preparation: The separator prepared above was punched into samples 50 mm wide and 100 mm long using a punching machine. Five samples were taken in parallel and placed on A4 paper and fixed in place. Next, the A4 paper with the samples placed on it was placed on cardboard with a thickness of 1 mm to 5 mm.

[0236] Sample test: Place an A4 sheet of paper on a cardboard box and place it in a blast oven. Set the oven temperature to 150°C. After the temperature reaches the set temperature and stabilizes for 30 minutes, 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.

[0237] 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 was used as the test result.

[0238] (2) Wet length test

[0239] The separator was cut into a 5 mm wide, 100 mm long sample, and both ends of the sample were fixed and placed horizontally. 0.5 mg of electrolyte was dropped onto the center of the sample. After 1 minute, a photograph was taken and the diffusion length of the electrolyte was measured to obtain the separator's wetting length. To ensure the accuracy of the test results, multiple samples (e.g., 5-10) were taken and tested, and the test results were obtained by calculating the average value. The electrolyte was prepared as follows: Ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 30:50:20 to obtain an organic solvent. Thoroughly dried LiPF6 was dissolved in the above organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0240] (3) Testing the capacity retention rate of secondary batteries

[0241] At 25°C, the secondary battery was charged to 4.3 V at a constant current of 1 / 3 C, then charged to a constant voltage of 4.3 V at a current of 0.05 C, left for 5 minutes, and then discharged to 2.8 V at a current of 1 / 3 C. The resulting capacity was recorded as the initial capacity C0. The above steps were repeated to determine the discharge capacity C of the secondary battery after 1000 cycles. 1000 When this is recorded, the capacity retention rate P of the secondary battery after 1000 cycles is 1000 =C 1000 / C0*100%.

[0242] Table 1 shows the test results for each parameter of the coatings of Examples 1 to 10 and Comparative Examples 1 and 2.

[0243] [Table 1]

[0244] As can be seen from the test results of Examples 1-10 and Comparative Examples 1-2 listed in Table 1, in the separators according to the present invention, the first particles are organic particles, and the average particle diameter D1 of the first particles and the average particle diameter D2 of the second particles in the coating satisfy the above-mentioned relationship, thereby allowing the first particles and the second particles to overlap well in the coating. When the substrate undergoes thermal shrinkage, the particles quickly press against each other, applying a force to the substrate in the opposite direction to the shrinkage, thereby improving the thermal safety of the secondary battery. Furthermore, the second particles filling the spaces between the organic particles creates more voids in the coating, further improving the wetting effect of the electrolyte on the separator, which promotes ion conduction within the separator and improves the cycle characteristics of the secondary battery.

[0245] Table 2 shows the test results for Examples 4, 11 to 14, and Comparative Example 3, where the coating contained first particles and second particles at different mass fractions.

[0246] [Table 2]

[0247] As can be seen from the test results of Examples 4, 11 to 14 and Comparative Example 3 listed in Table 2, by ensuring that the weight of the organic silicone resin particles and the weight of the second particles in the coating are in an appropriate ratio, not only can the degree of separator shrinkage be reduced, contributing to improved thermal safety of the secondary battery, but the organic silicone resin particles can also be well overlapped to form more voids, further improving the wetting effect of the electrolyte and improving the cycle characteristics of the secondary battery.

[0248] 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 embodiment that has substantially the same configuration as the technical idea or exhibits the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. Furthermore, various modifications that a person skilled in the art may make to the embodiments or other forms 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]

[0249] 1 battery pack 2 Upper box 3 Lower box 4 Battery Module 5 Secondary battery 51 Shell 52 Electrode Assembly 53 Lid plate

Claims

1. A separator, A substrate; a coating provided on at least one side of the substrate, the coating including first particles and second particles, the first particles being organic particles, and satisfying the relationship 1<D1 / D2≦10, where D1 is an average particle diameter of the first particles and D2 is an average particle diameter of the second particles; Separator.

2. 2≦D1 / D2≦8, and optionally 3≦D1 / D2≦7; The separator according to claim 1 .

3. 0.02 μm≦D1≦3.0 μm, and optionally 0.5 μm≦D1≦2 μm; The separator according to claim 1 or 2.

4. 0.01 μm≦D2≦2 μm, optionally 0.1 μm≦D2≦1 μm; The separator according to any one of claims 1 to 3.

5. The first particles satisfy at least one of the following characteristics: The separator according to any one of claims 1 to 4: (1) The volume distribution particle diameter of the first particles is D １ v90≦3.0 μm, and optionally 0.1 μm≦D １ v90≦2.0 μm; (2) The volume distribution particle diameter of the first particles is D １ v50≦2 μm, and optionally 0.01≦D １ v50≦1.5 μm; (3) The specific surface area of the first particles is 3 m ２ / g or more, optionally, 10m ２ / g to 100m ２ / g; (4) Regarding the particle size distribution of the first particles, (D １ v90-D １ v10) / D １ v50≦1.5 or less, and optionally 0.5≦(D １ v90-D １ v10) / D １ v50≦1.

0.

6. The second particles satisfy at least one of the following characteristics: The separator according to any one of claims 1 to 5: (1) The volume distribution particle diameter of the second particles is D ２ v90≦2 μm, and optionally 0.3 μm≦D ２ v90≦1.5 μm; (2) The volume distribution particle diameter of the second particles is D ２ v50≦1.5 μm, and optionally 0.2 μm≦D ２ v50≦1 μm; (3) The specific surface area of the second particles is 10 m ２ / g or more; (4) Regarding the particle size distribution of the second particles, (D ２ v90-D ２ v10) / D ２ v50≦1.0 and optionally 0.2≦(D ２ v90-D ２ v10) / D ２ v50≦0.

8.

7. wherein the weight percentage of the first particles in the coating is A and the weight percentage of the second particles in the coating is B, the coating satisfies 1<A / B≦10, and optionally 3≦A / B≦6. The separator according to any one of claims 1 to 6.

8. where A is the weight percentage of the first particles in the coating and B is the weight percentage of the second particles in the coating, the coating satisfies A≧50%, optionally 70%≦A≦90%, and / or the coating satisfies B≦35%, optionally 5%≦B≦25%. The separator according to any one of claims 1 to 7.

9. the first particles include one or more of organic silicone resin 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 organic silicone resin particles; The separator according to any one of claims 1 to 8.

10. the first particles include organosilicone resin particles, the organosilicone resin particles include a first polymer, the first polymer includes a first structural unit, a second structural unit, and a third structural unit; The first structural unit has a structure represented by formula (I): The second structural unit is represented by formula (II): The third structural unit is represented by formula (III): The separator according to any one of claims 1 to 9: Formula (I) 【Chemical 1】 In formula (I), R １ comprises a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl, and optionally R １ is one or more selected from a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl, R ２ includes one or more of substituted or unsubstituted C1 to C20 alkyl, substituted or unsubstituted C3 to C20 cycloalkyl, substituted or unsubstituted C1 to C20 hydroxyalkyl, and optionally, R ２ includes one or more of C1-C12 alkyl, C3-C12 cycloalkyl, C1-C12 hydroxyalkyl; 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, and optionally R ３ contains one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl; Formula (III) 【Chemistry 3】 In formula (III), R ４ ~R １１ each independently comprises one or more selected from substituted or unsubstituted C1 to C10 alkyl or a structural unit represented by formula (III-1), and R ４ ~R １１ At least one of the structural units is represented by formula (III-1): 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, and optionally R １２ contains one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl; R １３ includes one or more of substituted or unsubstituted C1-C10 alkyl, and optionally R １３ includes one or more of substituted or unsubstituted C3 to C10 alkyl.

11. where the molar content of the first structural unit is a %, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, is 65≦a≦95, and optionally 70≦a≦85; and / or where the molar content of the second structural unit is b %, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, is 0<b≦15, and optionally 5≦b≦10; and / or When the molar content of the third structural unit is c % based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, 0<c≦10, and optionally 5≦c≦9. The separator according to claim 10.

12. When the molar content of the first structural unit is a %, the molar content of the second structural unit is b %, and the molar content of the third structural unit is c %, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the organic silicone resin particles satisfy one or more of the following conditions (1) to (3): The separator according to claim 10 or 11: (1) 7≦a / b≦14; (2) 8≦a / c≦16; (3) a:b:c is (13-15):(2-4):(2-4).

13. the organic particles include organosilicone resin particles, the organosilicone resin particles include a second polymer, and the second polymer includes a structural unit represented by formula (a), Optionally, the second polymer comprises one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, and polymethylaminosiloxane; The separator according to any one of claims 1 to 12: Formula (a) 【Chemistry 5】 In formula (a), R １４ and R １５ each independently comprises one or more of substituted or unsubstituted C1-C10 alkyl, hydroxy, or amino, and optionally R １４ and R １５ are each independently one or more selected from substituted or unsubstituted C1 to C6 alkyl, hydroxy, or amino.

14. The number average molecular weight of the organic particles is 30,000 to 70,000, and optionally 40,000 to 50,000; The separator according to any one of claims 1 to 13.

15. The moisture content of the organic particles is 3000 μg / g or less, and optionally 600 μg / g to 2800 μg / g, based on the mass of the organic particles. The separator according to any one of claims 1 to 14.

16. the second particles include one or more of inorganic particles and polymer particles, and optionally the second particles include inorganic particles; The separator according to any one of claims 1 to 15.

17. The inorganic particles are one or more selected from inorganic particles having a dielectric constant of 5 or more, inorganic particles having the ability to conduct active ions, inorganic particles capable of electrochemical oxidation and reduction, and / or The polymer particles include one or more of organic silicone resin 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. The separator of claim 16.

18. The substrate satisfies at least one of the following characteristics: The separator according to any one of claims 1 to 17: (1) the thickness of the substrate is 16 μm or less, and optionally 3 μm to 9 μm; (2) The porosity of the substrate is 20% or more, and optionally 25% to 45%.

19. The coating satisfies at least one of the following characteristics: The separator according to any one of claims 1 to 18: (1) the thickness of the coating is 0.1 μm to 5 μm, optionally 0.5 μm to 3 μm; (2) The porosity of the coating is 20% or more, and optionally 25% to 50%.

20. The separator satisfies at least one of the following characteristics: The separator according to any one of claims 1 to 19: (1) The thermal shrinkage rate of the separator in the longitudinal direction at 150°C for 1 hour is 3% or less; (2) The thermal shrinkage rate of the separator in the transverse direction at 150°C for 1 hour is 2% or less; (3) The separator has an air permeability of 200 s / 100 mL or less, and optionally 150 s / 100 mL to 200 s / 100 mL; (4) The separator has a longitudinal tensile strength of 2700 kgf / cm ２ That is more than or equal to; (5) The separator has a tensile strength of 2500 kgf / cm in the transverse direction. ２ That is more than or equal to; (6) The wet length of the separator is 20 mm to 100 mm, and optionally 40 mm to 70 mm.

21. A method for producing the separator according to any one of claims 1 to 20, providing a substrate; mixing the first particles and the second particles 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, and drying the slurry film to form a coating to obtain a separator; the first particles are organic particles, and when an average particle diameter of the first particles is D1 and an average particle diameter of the second particles is D2, 1<D1 / D2≦10; Manufacturing method.

22. The separator according to any one of claims 1 to 20 or the separator obtained by the manufacturing method according to claim 21, Secondary battery.

23. The secondary battery according to claim 22, Power consuming device.

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