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

Abstract

This 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 contains particulate organic material. Let the weight per unit area of the one-sided coating be denoted as M, the thickness of the one-sided coating be denoted as H, and the true density of the organic material be denoted as ρ 有機 The separator satisfies M / (H×ρ 有機 )≧0.4, where the unit of M is g / m 2 , the unit of H is μm, and the unit of ρ 有機 is g / cm 3 . By virtue of having characteristics such as good heat resistance and ion transport characteristics, the heat safety performance and cycle performance of the battery using this separator can be improved.

Description

[Technical Field]

[0001] This application belongs to the field of battery technology and specifically relates to separators and methods for manufacturing the same, secondary batteries and power consumption devices. [Background technology]

[0002] Batteries, possessing excellent electrochemical and safety features, are widely used in many fields, including power tools, electric transportation equipment, aerospace, and energy storage devices. With the increasing prevalence and application of batteries in numerous fields, their thermal safety and cycle performance have become two key areas of focus in battery performance.

[0003] Currently, batteries still suffer from a defect in their thermal safety performance, which degrades when exposed to heat, and their cycle performance can also decrease. Therefore, it is necessary to improve both the thermal safety performance and cycle performance of batteries. [Overview of the Initiative]

[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. This separator has features such as good heat resistance and ion transport characteristics, thereby improving the thermal safety performance and cycle performance of secondary batteries using this separator.

[0005] A first aspect of this application provides a separator comprising a substrate and a coating installed on at least one side of the substrate, wherein the coating comprises particulate organic material, the weight per unit area of ​​the one-sided coating is denoted as M, the thickness of the one-sided coating is denoted as H, and the true density of the organic material is denoted as ρ 有機 It is written that the separator is M / (H×ρ 有機 ) ≥ 0.4, where the unit of M is g / m 2 The unit of H is μm, and ρ 有機 The unit is g / cm 3 That is the case.

[0006] In the separator according to the present application, the coating contains particulate organic material, and the separator satisfies 0.4 ≦ M / (H×ρ 有機 ), while on the one hand, the organic material in the coating can be reasonably deposited, and when the separator is heated, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinking direction of the separator, reducing the degree of shrinkage of the separator, and further reducing the risk of short circuit between the positive electrode and the negative electrode in the battery using this separator, so that the battery can have good thermal safety performance. On the other hand, while the organic material is reasonably deposited in the coating, more ion transport channels can be formed by the contact between the organic materials, and the infiltration of the electrolyte into the separator and the storage in the separator can be enhanced by these ion transport channels. Moreover, since it is advantageous for ion transport, the cycle performance of the battery can be improved.

[0007] In any embodiment of the present application, 0.5 ≦ M / (H×ρ 有機 ) ≦ 0.8. By the separator satisfying the above relationship, the organic material can be deposited more tightly by the coating, further reducing the degree of shrinkage of the separator, and while making the battery have good thermal safety performance, the cycle performance of the battery can be further improved.

[0008] In any embodiment of the present application, ρ 有機 ≦ 2.5. By setting the true density of the organic material within the above appropriate range, it can contribute to reducing the weight of the battery using this separator, and thus improving the mass energy density of the battery.

[0009] In any embodiment of the present application, 0.8 ≦ ρ 有機 ≦ 2.0.

[0010] In any embodiment of this application, M ≥ 0.5. The weight per unit area of ​​the one-sided coating satisfies the above relationship and further allows for more tight deposition of the organic material in the coating, and allows adjacent organic materials to come into contact with each other. When the separator is heated, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinkage of the separator, further reducing the degree of shrinkage of the separator, thereby reducing the occurrence of short circuits between the positive and negative electrodes.

[0011] In any embodiment of this application, 0.7 ≤ M ≤ 3.0.

[0012] In any embodiment of this application, H ≤ 3.0. The thickness H of the single-sided coating satisfies the above relationship, contributing to tight deposition between organic materials and further improving the thermal safety performance of the battery.

[0013] In any embodiment of this application, 0.5 ≤ H ≤ 2.0.

[0014] In any embodiment of this application, M / H ≥ 0.3.

[0015] In any embodiment of this application, 0.5 ≤ M / H ≤ 1.0.

[0016] In any embodiment of this application, the mass ratio of organic material in the coating is 60% or more, and selectively 75% to 95%.

[0017] In any embodiment of this application, the organic material comprises one or more of silicone particles, melamine-formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamide-imide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles, and optionally, the organic material comprises silicone particles.

[0018] In any embodiment of this application, the organic material comprises silicone particles, the silicone particles comprises a first polymer, the first polymer comprises a first structural unit, a second structural unit and a third structural unit, The first structural unit has the structure shown in formula (I), [ka] In formula (I), R1 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C5 alkyl groups, and selectively, R1 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl groups. R2 comprises one or more of substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C3-C20 cycloalkyl groups, and substituted or unsubstituted C1-C20 hydroxyalkyl groups, and selectively, R2 comprises one or more of C1-C12 alkyl groups, C3-C12 cycloalkyl groups, and C1-C12 hydroxyalkyl groups. The second structural unit is as shown in formula (II): [ka] In formula (II), R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C5 alkyl groups, and selectively, R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl groups. The third structural unit is as shown in equation (III): [ka] In equation (III), R4 to R 11 Each independently comprises a substituted or unsubstituted C1-C10 alkyl group, or one or more of the structural units shown in formula (III-1), where R4 to R 11 At least one of them is a structural unit shown in formula (III-1), [ka] In equation (III-1), R12 contains one or more of a hydrogen atom, or a substituted or unsubstituted C1-C5 alkyl group, and optionally, R 12 contains one or more of a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl group, R 13 contains a substituted or unsubstituted C1-C10 alkyl group, and optionally, R 13 contains a substituted or unsubstituted C3-C10 alkyl group.

[0019] In any embodiment of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, 70 ≦ a ≦ 90, and optionally, 75 ≦ a ≦ 85, and / or, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is denoted as b%, 0 < b ≦ 18, and optionally, 2 ≦ b ≦ 8, and / or, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is denoted as c%, 0 < c ≦ 15, and optionally, 4 ≦ c ≦ 10.

[0020] In any embodiment of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, the molar content of the second structural unit is denoted as b%, the molar content of the third structural unit is denoted as c%, and the silicone particles satisfy one or more of the conditions (1) to (3): (1) The condition that 5 ≦ a / b ≦ 10, (2) The condition that 6 ≦ a / c ≦ 15, (3) The condition that a:b:c is (14 - 16):(3 - 4):(1 - 4).

[0021] In any embodiment of the present application, the silicone particles contain a second polymer, and the second polymer contains a structural unit represented by the formula (a).

Chemical formula

[0022] In any embodiment of this application, the number-average molecular weight of the silicone particles is 25,000 to 60,000, and selectively 30,000 to 50,000. When the number-average molecular weight of the silicone particles is within the above range, it is advantageous for forming relatively small silicone particles. When applied to separators, it enables thin and light coating of the separator, reducing the overall thickness of the separator, thereby contributing to an improvement in the energy density of the battery. It also reduces the risk of the silicone particles clogging the substrate in the separator, thereby achieving the objective of improving the performance of the separator as a whole, such as its air permeability.

[0023] In any embodiment of this application, the water content of the silicone particles is 3000 μg / g or less, based on the mass of the silicone particles, and may be selectively between 700 μg / g and 2500 μg / g.

[0024] In any embodiment of this application, the volume distribution particle size Dv90 of the silicone particles satisfies Dv90 ≤ 4.0 μm. By setting the Dv90 of the silicone particles within the above appropriate range, the deposition density can be improved, and the energy density of the battery can be improved by providing an appropriate thickness to the coating.

[0025] In any embodiment of this application, the volume distribution particle size Dv90 of the silicone particles satisfies 0.5 μm ≤ Dv90 ≤ 30 μm.

[0026] In any embodiment of this application, the volume distribution particle size Dv50 of the silicone particles satisfies 1.0 μm ≤ Dv50 ≤ 2.5 μm.

[0027] In any embodiment of this application, the particle size distribution of the silicone particles is 0.5 ≤ (D V 90-D V 10) / D V The condition satisfies 50 ≤ 1.5.

[0028] In any embodiment of this application, the specific surface area of ​​the silicone particles is 35 m². 2 Less than / g, selectively 5m 2 / g~30m 2 The value is / g. By setting the specific surface area of ​​the silicone particles within the above appropriate range, the contact area between the silicone particles and the electrolyte can be increased, further contributing to the improvement of the electrolyte's penetration effect and liquid retention effect on the separator.

[0029] In any embodiment of this application, the thickness of the substrate is 12 μm or less.

[0030] In any embodiment of this application, the thickness of the substrate is 3 μm to 8 μm.

[0031] In any embodiment of this application, the substrate has a porous structure, and the porosity of the substrate is 20% or more.

[0032] In any embodiment of this application, the porosity of the substrate is 25% to 45%.

[0033] In any embodiment of this application, the separator has a longitudinal thermal shrinkage rate of 3% or less at 150°C for 1 hour.

[0034] In any embodiment of this application, the separator has a lateral thermal shrinkage rate of 2% or less at 150°C for 1 hour.

[0035] In any embodiment of this application, the air permeability of the separator is 200 s / 100 mL or less.

[0036] In any embodiment of this application, the air permeability of the separator is 150 s / 100 mL to 200 s / 100 mL.

[0037] In any embodiment of this application, the longitudinal tensile strength of the separator is 2700 kgf / cm². 2 That's all.

[0038] In any embodiment of this application, the lateral tensile strength of the separator is 2500 kgf / cm². 2 That's all.

[0039] A second aspect of this application provides a method for manufacturing the separator of the first aspect of this application, which manufacturing method is The steps include providing a substrate and The process involves mixing particulate organic material with a solvent to prepare a coating slurry, The process includes the steps of applying a coating slurry to at least one side of a substrate to form a slurry film layer, drying the slurry film layer to form a coating, and obtaining a separator. Here, M is the weight per unit area of ​​the single-sided coating, H is the thickness of the single-sided coating, and ρ is the true density of the organic material. 有機 It is written that the separator is M / (H×ρ 有機 ) ≥ 0.4, where the unit of M is g / m 2 The unit of H is μm, and ρ 有機 The unit is g / cm 3 That is the case.

[0040] A third aspect of this application provides a secondary battery comprising a separator according to the first aspect of this application or a separator manufactured by the method of the second aspect of this application.

[0041] A fourth aspect of this application provides a power consumption device, which includes a secondary battery according to a third aspect of this application. [Brief explanation of the drawing]

[0042] To more clearly illustrate the technical concept of the embodiments of this application, the following is a brief introduction to the drawings that may be used in the embodiments of this application. Obviously, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort. [Figure 1] This is a schematic diagram of one embodiment of the secondary battery of this application. [Figure 2] Figure 1 is an exploded schematic diagram of an embodiment of a secondary battery. [Figure 3] This is a schematic diagram of one embodiment of the battery module of this application. [Figure 4] This is a schematic diagram of one embodiment of the battery pack of this application. [Figure 5] Figure 4 is an exploded schematic diagram of an embodiment of the battery pack shown. [Figure 6] This is a schematic diagram of one embodiment including a power consumption device that uses a secondary battery of the present application as a power source.

[0043] In drawings, the drawings are not always drawn to the actual scale. [Modes for carrying out the invention]

[0044] The following describes in detail embodiments of the separator and its manufacturing method, secondary battery and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0045] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviation for any combination of real numbers a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and such solutions should be considered to be included in the disclosures of this application.

[0047] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts, and such technical concepts should be considered to be included in the disclosures of this application.

[0048] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0049] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may be open or closed. For example, such “includes” and “inclusion” may further include or include other components not listed, or may include or include only the components listed.

[0050] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and both A and B are true (or exist).

[0051] In this application, terms such as "first," "second," etc., are used solely for descriptive purposes and should not be understood as indicating or implying relative importance.

[0052] In this application, the terms "multiple" and "various" refer to two or more.

[0053] Unless otherwise specified, terms used in this application have the meanings commonly understood by those skilled in the art.

[0054] Unless otherwise specified, the numerical values ​​of each parameter referred to in this application can be tested using various commonly used test methods in the art, for example, they can be measured according to the test methods given in the embodiments of this application.

[0055] Generally, a battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is placed between the positive and negative electrode plates and primarily serves to prevent short circuits between the positive and negative electrodes, while also allowing active ions to pass freely and form a circuit.

[0056] Batteries, possessing excellent electrochemical and safety features, are widely used in many fields, including power tools, electric transportation equipment, aerospace, and energy storage devices. With the increasing prevalence and application of batteries in numerous fields, their thermal safety and cycle performance have become two key areas of focus in battery performance.

[0057] Separators are an important component in improving the thermal safety and cycle performance of batteries. Currently, commercially available batteries generally use porous polyolefin membranes, which have a relatively low melting point. This causes significant thermal contraction when heated, which not only reduces ion transport channels but also lowers ion conductivity, increases the internal resistance of the battery, and degrades its cycle performance. Furthermore, the contraction of the separator can cause the positive and negative electrodes inside the battery to come into direct contact, leading to an internal short circuit and further increasing the safety risk of the battery.

[0058] In view of this, this application provides a separator, a method for manufacturing the same, a secondary battery, and a power consumption device. This separator has features such as good heat resistance and ion transport characteristics, thereby improving the thermal safety performance and cycle performance of batteries using this separator.

[0059] Separator A first aspect of this application provides a separator comprising a substrate and a coating installed on at least one side of the substrate, wherein the coating comprises particulate organic material, the weight per unit area of ​​the one-sided coating is denoted as M, the thickness of the one-sided coating is denoted as H, and the true density of the organic material is denoted as ρ 有機 It is written that the separator is M / (H×ρ 有機 ) ≥ 0.4, where the unit of M is g / m 2 The unit of H is μm, and ρ 有機 The unit is g / cm 3 That is the case.

[0060] In the separator according to this application, the coating contains particulate organic material, and the separator is M / (H×ρ 有機 The condition )≧0.4 is satisfied, and on the one hand, the organic material can be rationally deposited in the coating, and when the separator is heated, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinkage direction of the separator, thereby reducing the degree of shrinkage of the separator and further reducing the risk of short circuits between the positive and negative electrodes in batteries using this separator, thereby giving the battery good thermal safety performance. On the other hand, while rationally depositing the organic material in the coating, the contact between the organic materials can also form more ion transport channels, and these ion transport channels can enhance the infiltration of the electrolyte into the separator and storage within the separator, which is advantageous for ion transport and can improve the battery's cycle performance.

[0061] In some embodiments of this application, the separator is 0.5 ≤ M / (H × ρ 有機 The condition ) ≤ 0.8 is satisfied. By satisfying the above relationship, the separator allows for tight deposition of organic material through coating, further reducing the degree of separator shrinkage, providing the battery with better thermal safety performance, and simultaneously improving the battery's cycle performance.

[0062] For example, M / (H×ρ 有機) may be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 or any two of the above values, but is not limited to these, and can be selectively M / (H×ρ 有機 The range of the value may be 0.4 to 0.8, 0.45 to 0.75, 0.5 to 0.7, 0.55 to 0.7, or 0.6 to 0.7.

[0063] In some embodiments of this application, the true density ρ of the organic material 有機 is, ρ 有機 The condition ≤2.5 is satisfied. By setting the true density of the organic material within the above appropriate range, it is possible to reduce the weight of the battery using this separator, and consequently improve the mass energy density of the battery.

[0064] In some other embodiments of this application, the true density ρ of the organic material 有機 0.8≦ρ 有機 It satisfies ≤ 2.0.

[0065] In some examples, the true density ρ of an organic material 有機 This range may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, or any two of the above values, but is not limited to these, and is selectively 0.1~2.5, 0.2~2.4, 0.3~2.3, 0.4~2.2, 0.5~2.1, 0.6~2.0, 0.7~1.9, 0.8~1.8, 0.9~1.7, 1.0~1.6, or 1.1~1.5.

[0066] The true density of organic materials has a known meaning in this art and can be measured by known methods in this art. For example, it can be tested by referring to GB / T 24586, specifically the following steps: Place a clean, dry sample cup on a balance and clear it to zero; add the powder sample to the sample cup, filling it to approximately half the volume of the sample cup; record the mass of the sample; place the sample cup containing the sample in a true density tester; seal the test system; introduce helium gas according to the procedure; and calculate the true volume based on Bore's law (PV=nRT) by detecting the gas pressure in the sample chamber and expansion chamber, thereby calculating the true density.

[0067] In some embodiments of this application, the weight M per unit area of ​​the one-sided coating satisfies the condition M ≥ 0.5. The weight per unit area of ​​the one-sided coating satisfies the above relationship and further allows for more tight deposition of the organic material in the coating, causing adjacent organic materials to come into contact with each other. When the separator is heated, the mutual pressing between the organic materials provides a force acting in the opposite direction to the shrinkage of the separator, further reducing the degree of shrinkage of the separator and thereby reducing the occurrence of short circuits between the positive and negative electrodes.

[0068] In some other embodiments of this application, the weight M per unit area of ​​the single-sided coating satisfies 0.7 ≤ M ≤ 3.0.

[0069] In some examples, the weight M per unit area of ​​the single-sided coating may be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 or any two of the above values, but is not limited to these. For example, it may be 0.5~2.0, 0.7~2.5, 0.75~2.0, 1.0~2.5, 1.0~2.0, or 1.0~1.8.

[0070] The weight per unit area of ​​a single-sided coating has a meaning known in the art and can be measured using methods known in the art. For example, it can be tested according to the following steps: Take a separator sample, punch it out into a small disc with an area of ​​S1, weigh it, and record it as M1. Next, remove the coating from the weighed sample, weigh the substrate, and record it as M0; (1) When the substrate has a coating on only one side, the weight per unit area of ​​the coating on one side = (M1-M0) / S1, (2) When the substrate has a coating on both sides, the weight per unit area of ​​the coating on one side = (M1-M0) / S1 / 2, In some embodiments of this application, the thickness H of the coating on one side satisfies the condition H ≤ 3.0. The thickness H of the coating on one side satisfies the above relationship and can contribute to tight deposition between organic materials. Thus, when the separator is heated, the tight deposition between organic materials can quickly provide a force opposite to the direction of the separator's contraction, further reducing the degree of separator contraction and decreasing the occurrence of short circuits between the positive and negative electrodes, thereby achieving the objective of improving the thermal safety performance of the battery.

[0071] In some other embodiments of this application, the coating thickness H satisfies 0.5 ≤ H ≤ 2.0.

[0072] In some examples, the coating thickness H may be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 or a range consisting of any two of the above values, but is not limited to these. For example, it may be 0.5~2.5, 0.7~2.5, 0.8~2.8, 0.9~2.0, 1.0~2.5, or 1.0~2.0.

[0073] The thickness of the single-sided coating has a meaning known in this art and can be measured using methods known in this art. For example, the test can be performed using a thickness gauge instrument, referring to the GB / T36363-2018 standard for polyolefin separators for lithium-ion batteries.

[0074] In some embodiments of this application, the weight M per unit area of ​​the one-sided coating and the thickness H of the one-sided coating satisfy M / H ≥ 0.3.

[0075] In some embodiments of this application, the weight M per unit area of ​​the one-sided coating and the thickness H of the one-sided coating satisfy 0.5 ≤ M / H ≤ 1.0.

[0076] It should be noted that each coating parameter given in this application (e.g., thickness, weight per unit area, etc.) refers to the coating parameter for one side only. When a coating is applied to both sides of a substrate simultaneously, it is considered that the coating falls within the scope of protection of this application if the coating parameter for either side satisfies the requirements of this application.

[0077] In some embodiments of this application, the organic material includes one or more of the following: silicone particles, melamine-formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamide-imide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles.

[0078] In some selective embodiments of this application, the organic material includes silicone particles. These silicone particles refer to organosiloxanes whose main chain consists of silicon bonds (-Si-O-Si-). Because silicon bonds are inorganic bonds, they have relatively high bond energy, which can impart high heat resistance and chemical stability to the silicone. For example, the silicone can be used for extended periods at temperatures below 200°C. The side chains of the silicone may or may not be grafted with other groups, or they may be grafted with organic groups. When organic groups are grafted, good dispersibility can be imparted to the silicone, improving the coating performance of the silicone coating and its affinity to the substrate. The dispersion of silicone particles in the coating gives the separator good heat resistance, thereby improving the thermal safety performance of the secondary battery. Furthermore, a structure with voids between the silicone particles can be formed, further improving the penetration and retention characteristics of the separator in the electrolyte. This promotes the transport of active ions in the separator, thereby improving the cycle performance of the secondary battery when the separator is applied to a secondary battery.

[0079] In some embodiments of this application, the silicone particles comprise a first polymer, the first polymer comprising a first structural unit, a second structural unit, and a third structural unit.

[0080] The first structural unit has the structure shown in formula (I), [ka] In formula (I), R1 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C5 alkyl groups, and selectively, R1 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl groups. R2 comprises one or more of substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C3-C20 cycloalkyl groups, and substituted or unsubstituted C1-C20 hydroxyalkyl groups, and selectively, R2 comprises one or more of C1-C12 alkyl groups, C3-C12 cycloalkyl groups, and C1-C12 hydroxyalkyl groups. The second structural unit is as shown in formula (II): [ka] In formula (II), R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C5 alkyl groups, and selectively, R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl groups. The third structural unit is as shown in equation (III): [ka] In equation (III), R4 to R 11 Each independently comprises a substituted or unsubstituted C1-C10 alkyl group, or one or more of the structural units shown in formula (III-1), where R4 to R 11 At least one of them is a structural unit shown in formula (III-1), [ka] In equation (III-1), R 12 It comprises a hydrogen atom, or one or more substituted or unsubstituted C1-C5 alkyl groups, and selectively, R 12 R includes a hydrogen atom, or one or more substituted or unsubstituted C1-C3 alkyl groups. 13 It comprises a substituted or unsubstituted C1-C10 alkyl group, and selectively, R 13 It contains substituted or unsubstituted C3-C10 alkyl groups.

[0081] In the above embodiment, the first structural unit can adjust the glass transition temperature of the first polymer, improve the toughness and peel strength of the polymer, and contribute to the good adhesion. The second structural unit can produce excellent swelling resistance and high adhesion. Furthermore, when the first polymer is applied as a separator, the first polymer comes into contact with the electrolyte and does not swell easily, thus exhibiting relatively excellent swelling resistance. The third structural unit includes a framework structure composed of Si-O-Si or Si-O bonds, which can provide the first polymer with advantages in terms of heat resistance and mechanical performance. Furthermore, it can provide good thermal stability to the separator during the long-term cycle charge-discharge process of the battery, effectively isolate the positive and negative electrode plates, and thereby ensure the thermal safety performance of the battery.

[0082] Furthermore, the first structural unit and the third structural unit work together to exert a synergistic effect, improving the adhesion and heat resistance of the first polymer, and the first structural unit and the second structural unit work together to exert a synergistic effect, improving the swelling resistance of the first polymer. Therefore, the first polymer can not only improve the adhesion between the coating and the substrate, but also strengthen the heat resistance of the separator, thereby improving the thermal safety performance of the battery.

[0083] In some embodiments of this application, the molar content of the first structural unit is denoted as a%, based on the total molar amount of the first, second, and third structural units, with a value of 70 ≤ a ≤ 90. When the molar content of the first structural unit is within the above range, the adhesion of the first polymer is significantly improved, and when the first polymer is applied as a separator, the bonding strength between the first polymer and the separator substrate can be improved. Selectively, a value of 75 ≤ a ≤ 85 is also possible. Exemplarily, the molar content of the first structural unit may be in the range of 70%, 75%, 80%, 85%, 90%, or any two of the above values.

[0084] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is denoted as b%, and 0 < b ≤ 18. When the molar content of the second structural unit is within the above range, the swelling resistance of the first polymer can be significantly improved. Optionally, 2 ≤ b ≤ 8. Exemplarily, the molar content of the second structural unit may be 5%, 8%, 10%, 12%, 15%, 18%, or a range consisting of any two of the above numerical values.

[0085] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is denoted as c%, and 0 < c ≤ 15. When the molar content of the third structural unit is within the above range, the heat resistance of the first polymer can be improved. Optionally, 4 ≤ c ≤ 10. Exemplarily, the molar content of the third structural unit may be 5%, 8%, 10%, 12%, 15%, or a range consisting of any two of the above numerical values.

[0086] The first structural unit in the first polymer can impart good adhesion to the first polymer. However, when the first polymer is applied to a separator, contact with the electrolyte cannot be avoided. Therefore, the swelling action of the electrolyte reduces the adhesion of the first polymer to some extent. The cyano group contained in the second structural unit in the first polymer exhibits a synergistic effect with the first structural unit and can improve both the swelling resistance and adhesion of the first polymer. Therefore, when the molar content a of the first structural unit and the molar content b of the second structural unit satisfy 5 ≤ a / b ≤ 10, a more sufficient synergistic effect can be exerted between the first structural unit and the second structural unit, and the adhesion and swelling resistance of the first polymer can be improved. Exemplarily, a / c may be 5, 6, 7, 8, or a range consisting of any two of the above numerical values.

[0087] The first structural unit in the first polymer imparts good adhesion to the first polymer, but its own heat resistance is relatively poor. When the first polymer is applied as a separator, as the battery charge and discharge time increases, the temperature inside the battery rises, which can cause the first structural unit to break down. The first polymer further contains a third structural unit, and the inorganic structure of polysilsesquioxane in the third structural unit works synergistically with the first structural unit to improve the overall heat resistance and adhesion of the first polymer. Therefore, when the molar content a of the first structural unit and the molar content c of the third structural unit satisfy 6 ≤ a / c ≤ 15, a more sufficient synergistic effect is exerted between the first and third structural units, improving the adhesion and heat resistance of the first polymer. Exemplarily, a / c may be in the range of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or any two of the above values.

[0088] In some embodiments of this 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=(14-16):(3-4):(1-4). When the degrees of polymerization of the first, second, and third structural units satisfy the above ratio, the three types of structural units in the silicone particles cooperate with each other to exhibit their respective performance advantages, thereby improving the adhesion, thermal stability, and swelling resistance of the polymer.

[0089] The first structural unit includes multiple chemical structures, and the specific chemical structure of the first structural unit will be described next.

[0090] In some embodiments of this application, R1 comprises a hydrogen atom and / or a methyl group.

[0091] In some embodiments of this application, R2 includes one or more of the following: a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a dodecyl group, or an isobornyl group.

[0092] For example, the first structural unit includes one or more of the structures shown in formula (I-1) to formula (I-8), [ka]

[0093] The second structural unit includes multiple chemical structures, and the specific chemical structure of the second structural unit will be described next.

[0094] In some embodiments of this application, R3 comprises a hydrogen atom and / or a methyl group.

[0095] For example, the second structural unit includes one or more of the structures shown in formula (II-1) to formula (II-4), [ka]

[0096] The third structural unit includes multiple chemical structures, and the specific chemical structures of the third structural unit will be described next.

[0097] In some embodiments of this application, R4 to R 11 Each independently contains the structural unit shown in formula (III-1), and selectively, R 12 is comprised of one or more of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or an n-pentyl group, and / or R 13 This includes one or more of the following: n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-octyl group, isooctyl group, or 2-ethylhexyl group.

[0098] In this application, the type of group in the first polymer can be measured by infrared spectroscopy. For example, the type of modifying group may be determined by testing the infrared absorption spectrum of the material and determining the characteristic peaks contained therein. Specifically, infrared spectroscopy may be performed on the material using instruments and methods known in the art, for example, by employing an infrared spectrometer (e.g., an IS10 Fourier transform infrared spectrometer from Nicolet, USA) and testing in accordance with GB / T 6040-2019 General Rules for Infrared Spectroscopic Analysis.

[0099] In some embodiments of this application, the infrared spectrum of the first polymer shows the presence of ester groups at 1750 cm⁻¹. -1 From 1735cm -1 It has characteristic peaks.

[0100] In some embodiments of this application, the infrared spectrum of the first polymer shows 2260 cm⁻¹, indicating the presence of cyano groups. -1 From 2220cm -1 It has characteristic peaks.

[0101] In some embodiments of this application, the infrared spectrum of the first polymer shows the presence of a Si-O-Si framework of silsesquioxane at 1100 cm⁻¹. -1 From 1120cm -1 It has characteristic peaks.

[0102] In some embodiments of this application, the first polymer may be obtained by the following method, which is: Step S100 provides a first monomer, a second monomer and a third monomer, The method includes step S200, which involves mixing a first monomer, a second monomer, and a third monomer, and generating a polymerization reaction under the action of an initiator to produce a first polymer.

[0103] This application describes a method in which a first monomer, a second monomer, and a third monomer are mixed and then copolymerized, and the resulting first polymer is a copolymer of the three monomers.

[0104] The first monomer has the structure shown in formula (IV), [ka] In formula (IV), R1 is selected from a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group, and selectively, R1 is selected from a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group. R2 is selected from substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C3-C20 cycloalkyl groups, and substituted or unsubstituted C1-C20 hydroxyalkyl groups. Selectively, R2 is selected from C1-C12 alkyl groups, C3-C12 cycloalkyl groups, and C1-C12 hydroxyalkyl groups.

[0105] The first monomer is an acrylate compound, and when it polymerizes, the carbon-carbon double bond opens to form the first structural unit.

[0106] Exemplary examples, the first monomer includes one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0107] The second monomer has the structure shown in formula (V), [ka] In formula (V), R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C5 alkyl groups, and selectively, R3 comprises one or more hydrogen atoms or substituted or unsubstituted C1-C3 alkyl groups.

[0108] The second monomer is an acrylonitrile compound, and when it polymerizes, the carbon-carbon double bond opens to form a second structural unit.

[0109] For example, the second monomer includes acrylonitrile and / or methacrylonitrile.

[0110] The third monomer shown has the structure shown in formula (VI), [ka] In equation (VI), R 30 From R 37 Each independently comprises a substituted or unsubstituted C1-C10 alkyl group, or one or more of the structural units shown in formula (VI-1), where R 30 From R 37 At least one of them is a structural unit shown in formula (VI-1), [ka] In equation (VI-1), R 12 It comprises a hydrogen atom, or one or more substituted or unsubstituted C1-C5 alkyl groups, and selectively, R 12 It contains a hydrogen atom, or one or more substituted or unsubstituted C1-C3 alkyl groups. R 13 It comprises a substituted or unsubstituted C1-C10 alkyl group, and selectively, R 13 It contains substituted or unsubstituted C3-C10 alkyl groups.

[0111] Exemplary examples, the third monomer includes one or more of methacryloyloxypropyl cage-type polysylsesquioxane, methacryloyloxypropyl heptaysorbyl polysylsesquioxane, acryloyloxypropyl cage-type polysylsesquioxane, acryloyloxypropyl heptaysorbyl polysylsesquioxane, and methacryloyloxypropyl heptaoctyl polysylsesquioxane.

[0112] In some embodiments of this application, step S200 is specifically Step S210 involves adding the first monomer, the second monomer, and the third monomer to the solvent and emulsifier and mixing them to form a mixed system. The process includes step S220, in which an initiator is added to the mixed system, and a polymerization reaction is initiated by the action of the initiator to produce a first polymer.

[0113] This application describes a polymerization method in which multiple monomers may be copolymerized using emulsion polymerization, which is a simpler polymerization method. Of course, this application may also use other polymerization methods, such as solution polymerization or suspension polymerization, and the process parameters used in the polymerization process may be selected from general parameters in this art, which will not be explained further here.

[0114] In some embodiments of this application, the emulsifier comprises one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, alkyl group diphenyl oxide disulfonate, and ethoxylated alkyl group phenol sulfate ammonium.

[0115] In some embodiments of this application, the ratio of the mass percentage content of the emulsifier to the mass percentage content of the first monomer, second monomer, and third monomer, based on the total mass of the mixed system, is from 0.1% to 5%, that is, the amount of emulsifier used is from 0.1% to 5% of the mass of the three monomers. When the mass percentage content of the emulsifier is within the above range, the first monomer, second monomer, and third monomer may be emulsified and dispersed in a solvent to form a relatively homogeneous system.

[0116] In some embodiments of this application, the initiator comprises potassium persulfate and / or ammonium persulfate.

[0117] In some embodiments of this application, the ratio of the mass percentage content of the initiator to the mass percentage content of the first monomer, second monomer, and third monomer, based on the total mass of the mixed system, is between 0.15% and 1%, i.e., the amount of initiator used is between 0.1% and 5% of the mass of the three monomers. When the mass percentage content of the initiator is within the above range, sufficient polymerization can be guaranteed.

[0118] In some embodiments of this application, the solvent may include water, for example, deionized water.

[0119] As a specific example, this method includes the following:

[0120] Prepolymer production: Deionized water, emulsifier, first polymerization monomer, second polymerization monomer, and third polymerization monomer are mixed and stirred uniformly to obtain a prepolymer. First polymer preparation: Add emulsifier and deionized water to a container and stir for 30 to 60 minutes to emulsify and obtain a homogeneous and stable emulsion. Then, slowly add the prepolymer and initiator solution (potassium persulfate and / or ammonium persulfate, the initiators, dissolved in deionized water to form the solution) prepared in the previous step dropwise. After the addition is complete, raise the temperature to 90°C to 110°C and maintain the temperature for 0.5 hours to allow the reaction to proceed. Cool to 40°C, adjust the pH to 7 to 8 with ammonia water, filter, drain, and dry to obtain the polymer.

[0121] In some embodiments of this application, the silicone particles comprise a second polymer, the second polymer comprises a structural unit shown in formula (a), [ka] In equation (a), R 14 and R 15Each is independently selected from substituted or unsubstituted C1-C10 alkyl groups, hydroxyl groups, or amino groups. Selectively, R 14 and R 15 Each of these is independently selected from substituted or unsubstituted C1-C6 alkyl groups, hydroxyl groups, or amino groups.

[0122] For example, the silicone particles include at least one of the structures shown in formula (a-1) to formula (a-5), [ka]

[0123] In this application, the terms "first polymer" and "second polymer" are used solely to distinguish between types of materials and do not serve as limiting orders or quantities.

[0124] In some embodiments of this application, the number-average molecular weight of the silicone particles is 25,000 to 60,000, and selectively 30,000 to 50,000. Exemplarily, the number-average molecular weight of the silicone particles may be in the range of 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, or any two of the above values. When the number-average molecular weight of the silicone particles is within the above range, it has a relatively high viscosity, which is advantageous in improving the adhesion between the separator and the positive and negative electrode plates when the silicone particles are applied as a separator. When the number-average molecular weight of the silicone particles falls within the above range, it is advantageous for forming relatively small silicone particles. When applied to separators, it enables thin coating of the separator, reducing the overall thickness of the separator, thereby contributing to an improvement in the energy density of secondary batteries. Furthermore, because the silicone particles formed are not too small, the risk of the silicone particles clogging the substrate in the separator is reduced, improving the overall performance of the separator, such as its air permeability.

[0125] In this application, the number-average molecular weight of the first polymer can be measured by gel permeation chromatography (GPC). Specifically, the measurement was performed using a Waters GPC1515 instrument in the United States. The sample was dissolved in tetrahydrofuran for a dissolution time of 12 hours or more, the sample concentration was 4 mg / mL, the sample was prepared by filtration, the measurement temperature was 25°C, and the measurement flow rate was 1 ml / min.

[0126] The inventors conducted further research and discovered that during the long-term charge-discharge process of a battery, moisture in the separator is gradually released and enters the electrolyte. The electrolyte is highly sensitive to moisture and readily generates hydrofluoric acid (HF) upon contact with water, which increases the acidity of the electrolyte, potentially causing corrosion of the active material and current collector, and leading to the leaching of transition metal ions from the active material, thereby affecting the electrochemical performance of the battery. Accordingly, this application adjusts the moisture content of silicone particles to 3000 μg / g or less, selectively adjusting it to 700 μg / g to 2500 μg / g, calculated based on the mass of the silicone particles. When the moisture content of the silicone particles is within the above range, the amount of moisture contained is relatively low, reducing the risk of side reactions in the electrolyte during the long-term charge-discharge cycle process of the battery, thereby improving the electrochemical performance of the battery. For example, the moisture content of the silicone particles may be in the range of 700 μg / g, 800 μg / g, 1000 μg / g, 1200 μg / g, 1500 μg / g, 1800 μg / g, 2000 μg / g, 2500 μg / g, 3000 μg / g, or any two of the above values.

[0127] In this application, the moisture content of silicone particles can be measured with a moisture meter, the test method may be the Karl Fischer moisture meter, and the test instrument may be the Swiss Metrohm Model 831 Karl Fischer moisture meter.

[0128] In some embodiments of this application, the volume distribution particle size Dv90 of the silicone particles satisfies Dv90 ≤ 2.0 μm. By setting the Dv90 of the silicone particles within the above appropriate range, the deposition density can be improved, and the energy density of the battery can be improved by providing an appropriate thickness to the coating.

[0129] In some other embodiments of this application, the volume distribution particle size Dv90 of the silicone particles satisfies 0.5 μm ≤ Dv90 ≤ 1.5 μm.

[0130] In some examples, the volume distribution particle size Dv90 of the silicone particles may be, but is not limited to, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 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, or any two of the above values.

[0131] In some embodiments of this application, the volume distribution particle size Dv50 of the silicone particles satisfies 1.0 μm ≤ Dv50 ≤ 2.5 μm. In some embodiments of this application, the particle size distribution of the silicone particles is 0.5 ≤ (D V 90-D V 10) / D V The condition satisfies 50 ≤ 1.5.

[0132] In this application, the volume distribution particle size Dv90 of the material has a meaning known in the art, representing the particle size corresponding to the point 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, it can be measured using a laser particle size analyzer (e.g., Master Size 3000) with reference to the GB / T 19077-2016 particle size distribution laser diffraction method.

[0133] In this application, the volume distribution particle size Dv50 of the material has a meaning known in the art, representing the particle size corresponding to the point 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, it can be measured using a laser particle size analyzer (e.g., Master Size 3000) with reference to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0134] In this application, the volume distribution particle size Dv10 of the material has a meaning known in the art, representing the particle size corresponding to the point 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, it can be measured using a laser particle size analyzer (e.g., Master Size 3000) referring to the GB / T 19077-2016 particle size distribution laser diffraction method.

[0135] In some embodiments of this application, the specific surface area of ​​the silicone particles is 35 m². 2 Less than / g, selectively 5m 2 / g~30m 2 The value is / g. By setting the specific surface area of ​​the silicone particles within the above appropriate range, the contact area between the silicone particles and the electrolyte can be increased, further contributing to the improvement of the electrolyte's penetration effect and liquid retention effect on the separator.

[0136] In this application, the specific surface area of ​​a particle has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be tested using the nitrogen gas adsorption specific surface area analysis test method, referring to GB / T 19587-2017, and calculated using the BET (Brunauer-Emmett-Teller) method. Selectively, the nitrogen gas adsorption specific surface area analysis test can be performed using the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, Inc., USA.

[0137] In some examples, the specific surface area of ​​silicone particles is 3m². 2 / g, 3.5m2 / 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 It may be in the range consisting of / g or any two of the above numerical values, but is not limited thereto.

[0138] In some embodiments of this application, the substrate thickness is 12 μm or less. Selectively, the substrate thickness is 3 μm to 8 μm. Since the coating of this application can improve the thermal safety and cycle performance of the separator, even thinner substrates can be selected, thereby contributing to a further improvement in the energy density of the battery.

[0139] In some embodiments of this application, the substrate has a porous structure, and the porosity of the substrate is 20% or more. Selectively, the porosity of the substrate is 25% to 45%. When the porosity of the porous substrate is within the above appropriate range, it is advantageous to further improve the ion transport characteristics of the separator and improve the cycle performance of the battery.

[0140] This application does not particularly limit the material of the substrate, and any known substrate having good chemical and mechanical stability can be selected. For example, the substrate may include at least one of porous polyolefin resin films (e.g., polyethylene, polypropylene, and polyvinylidene fluoride), porous glass fibers, and porous nonwoven fabrics. The porous substrate may be a single-layer film or a multilayer composite film. If the porous substrate is a multilayer composite film, the materials of each layer may be the same or different.

[0141] In some embodiments of this application, the separator has a longitudinal thermal shrinkage rate of 3% or less at 150°C for 1 hour.

[0142] In some embodiments of this application, the separator has a lateral thermal shrinkage rate of 2% or less at 150°C for 1 hour.

[0143] In the above embodiment, the separator of this application has a low thermal shrinkage rate in both the lateral and vertical directions, which can further improve the thermal safety performance of the battery.

[0144] In some embodiments of this application, the permeability of the separator is 200 s / 100 mL or less. Selectively, the permeability of the separator is 150 s / 100 mL to 200 s / 100 mL. The separator of this application has good permeability, which improves ion transport characteristics, reduces battery resistance, and improves battery cycle performance.

[0145] In some embodiments of this application, the longitudinal tensile strength of the separator is 2700 kgf / cm². 2 That's all.

[0146] In some embodiments of this application, the lateral tensile strength of the separator is 2500 kgf / cm². 2 That's all.

[0147] In the above embodiment, the separator of this application has high tensile strength in both the lateral and longitudinal directions, which reduces the probability of the separator breaking when the battery expands, thereby further improving the safety performance of the battery.

[0148] In this application, the thermal 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, all of these may be tested by referring to standard GB / T 36363-2018.

[0149] It should be noted that the coating parameters for the separators mentioned above are all coating parameters for one side of the substrate.

[0150] If the coating is applied to both sides of the substrate, it is considered that the protection of this application will be within the scope of protection if the coating parameters on either side satisfy the requirements of this application.

[0151] Separator manufacturing method A second aspect of this application provides a method for manufacturing the separator of the first aspect of this application, comprising the steps of: S1 providing a substrate; S2 mixing particulate organic material with a solvent to prepare a coating slurry; and S3 applying the coating slurry to at least one side of the substrate to form a slurry film layer, drying the slurry film layer to form a coating, and obtaining a separator, where M is the weight per unit area of ​​the one-sided coating, H is the thickness of the one-sided coating, and ρ is the true density of the organic material. 有機 It is written that the separator is M / (H×ρ 有機 ) ≥ 0.4, where the unit of M is g / m 2 The unit of H is μm, and ρ 有機 The unit is g / cm 3 That is the case.

[0152] In some embodiments of this application, in S2, the solvent may be water, for example, deionized water. The adhesive may be an aqueous solution adhesive, which is advantageous for the production and application of coating slurries because it has the advantages of high thermodynamic stability and being environmentally friendly. For example, the aqueous solution adhesive may contain at least one of the following: aqueous solution acrylic resin (e.g., acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other copolymer monomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer, and polyacrylamide. The coating slurry may also further contain other components, such as dispersants and wetting agents.

[0153] In some embodiments of this application, coating is performed using a coating machine in S3. This application does not particularly limit the model of the coating machine, and commercially available coating machines may be used, for example. Optionally, the coating machine includes an intaglio roller, which is used to transfer the coating slurry onto the substrate. Optionally, the line count of the intaglio roller is 100 LPI to 200 LPI, and more optionally, 150 LPI to 180 LPI. Furthermore, the coating method may include transfer coating, rotary spray coating, dipping coating, etc.

[0154] In some embodiments of this application, in S3, the coating speed may be controlled between 30 m / min and 120 m / min, for example between 60 m / min and 90 m / min. When the coating speed is within the above range, coating surface problems can be effectively reduced, and the probability of uneven coating can be decreased, thereby further improving the energy density and safety performance of the battery.

[0155] The performance of the separator of this application can be further improved by controlling each of the above process parameters within a given range. Those skilled in the art may selectively adjust and control one or more of the above process parameters according to actual production conditions.

[0156] The separator manufacturing method of this application is obtained by manufacturing the coating in a single application, thereby significantly simplifying the separator manufacturing process flow.

[0157] Some of the raw materials used in the method for manufacturing the separator of this application, and parameters such as their content, can be found by referring to the separator of the first embodiment of this application and will not be described further here. Unless otherwise specified, each of the raw materials used in the method for manufacturing the separator of this application can be purchased commercially.

[0158] secondary battery A third embodiment of the present invention provides a secondary battery. A secondary battery, also called a rechargeable battery or storage battery, is a battery that can be used continuously by activating the active material through charging after battery discharge. Generally, a secondary battery includes an electrode assembly and an electrolyte, the electrode assembly includes a positive electrode plate, a negative electrode plate and a separator, the separator is placed between the positive electrode plate and the negative electrode plate and mainly serves to prevent short circuits between the positive and negative electrodes and allows active ions to pass through.

[0159] This application does not particularly limit the type of secondary battery; for example, the secondary battery may be a lithium-ion battery, a sodium-ion battery, or the like, and in particular, the secondary battery may be a lithium-ion secondary battery.

[0160] The secondary battery of this application includes a separator obtained by the first embodiment of this application or the manufacturing method of the second embodiment of this application, the separator being interposed between a positive electrode plate and a negative electrode plate. Selectively, the separator has the coating of this application on at least one side of the separator closer to the negative electrode plate. As a result, the secondary battery of this application has relatively good thermal safety performance and cycle performance.

[0161] [Positive electrode plate] In some embodiments of this application, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector and containing positive electrode active material. For example, the positive electrode current collector has two opposing sides in the thickness direction of itself, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0162] If the secondary battery of this application is a lithium-ion secondary battery, the positive electrode active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium-containing transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds.

[0163] In some embodiments of the present application, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium-ion secondary battery 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 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.

[0164] As an example, the positive electrode active material used in the lithium-ion secondary battery may include at least one of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (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 O2, LiFePO4, LiMnPO4.

[0165] When the secondary battery of the present application is a sodium-ion secondary battery, the positive electrode active material may include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue-based materials.

[0166] For example, the positive electrode active materials used in sodium-ion secondary batteries include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and 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 is X p M' q (PO4) r O x Y 3-x It may contain at least one of the materials that are 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 + At least one of the following is selected, where M' is a transition metal cation, selectively at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, and Y is a halogen anion, selectively at least one of F, Cl, and Br.

[0167] In this application, the modifying compounds for each of the above-mentioned positive electrode active materials modify the positive electrode active material by doping and / or surface coating.

[0168] In some embodiments of this application, the cathode film layer further optionally comprises a cathode conductive agent. This application is not particularly limited to the type of cathode conductive agent, and as an example, the cathode conductive agent includes 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 this application, the mass percentage content of the cathode conductive agent is ≤6 wt% based on the total weight of the cathode film layer.

[0169] In some embodiments of this application, the cathode film layer optionally further comprises a cathode adhesive. This application is not particularly limited to the type of cathode adhesive, and as an example, the cathode adhesive may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins. In some embodiments of this application, the mass percentage content of the cathode adhesive is ≤5 wt% based on the total weight of the cathode film layer.

[0170] In some embodiments of this application, the positive electrode current collector may be a metal foil sheet or a composite current collector. As an example of a metal foil sheet, aluminum foil can be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer. As an example, the metal material may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0171] The positive electrode film layer is generally obtained by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, a selective conductive agent, a selective adhesive, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0172] [Negative electrode plate] In some embodiments of this application, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector and containing a negative electrode active material. For example, the negative electrode current collector has two opposing sides in the thickness direction of itself, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0173] The negative electrode active material can be any negative electrode active material known in the art for secondary batteries. For example, the negative electrode active material may include, but is not limited to, natural graphite, artificial graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may include at least one of elemental silicone, silicone oxide, silicone-carbon composite, silicone-nitrogen composite, and silicone alloy material. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0174] In some embodiments of this application, the negative electrode film layer further optionally comprises a negative electrode conductive agent. This application is not particularly limited to the type of negative electrode conductive agent, and as an 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 this application, the mass percentage content of the negative electrode conductive agent is ≤7 wt% based on the total weight of the negative electrode film layer.

[0175] In some embodiments of this application, the negative electrode film layer optionally further comprises a negative electrode adhesive. This application is not particularly limited to the type of negative electrode adhesive, and as an example, the negative electrode adhesive may comprise at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments of this application, the mass percentage content of the negative electrode adhesive is ≤6 wt% based on the total weight of the negative electrode film layer.

[0176] In some embodiments of this application, the negative electrode film layer selectively further comprises other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, etc. In some embodiments of this application, the mass percentage content of the other additives is ≤3 wt% based on the total weight of the negative electrode film layer.

[0177] In some embodiments of this application, the negative electrode current collector may be a metal foil sheet or a composite current collector. Copper foil can be used as an example of a metal foil sheet. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer. For example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys. For example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0178] The negative electrode film layer is generally obtained by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, a selective conductive agent, a selective adhesive, and other selective auxiliary agents in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0179] The negative electrode plate does not exclude any additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode plate of this application further includes a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and installed on the surface of the negative electrode current collector. In some other embodiments, the negative electrode plate of this application further includes a protective layer covering the surface of the negative electrode film layer.

[0180] [Electrolyte] During the charging and discharging process of a secondary battery, active ions intermittently move between the positive and negative electrodes, undergoing absorption and release, while the electrolyte plays a role in conducting these active ions between the positive and negative electrodes. This application does not particularly limit the type of electrolyte, and it can be selected according to actual needs.

[0181] The electrolyte solution contains an electrolyte salt and a solvent. The types of electrolyte salt and solvent are not specifically limited and can be selected according to actual needs.

[0182] If the secondary battery of this application is a lithium-ion secondary battery, the electrolyte salt may, for example, include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), 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 (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0183] If the secondary battery of this application is a sodium-ion secondary battery, the electrolyte salt may, for example, include at least one of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorobis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP).

[0184] For example, the solvent may include, but is not limited to, at least one of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0185] In some embodiments of this application, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and may further include additives that can improve some performance aspects of the secondary battery, such as additives that improve the overcharge performance of the secondary battery, additives that improve the high-temperature performance of the secondary battery, and additives that improve the low-temperature power performance of the secondary battery.

[0186] In some embodiments of this application, the positive electrode plate, separator and negative electrode plate may be manufactured into an electrode assembly by a winding process and / or a lamination process.

[0187] In some embodiments of this application, the secondary battery may further include an outer casing. This outer casing may be used to package the electrode assembly and the electrolyte.

[0188] In some embodiments of the present application, the exterior of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0189] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other arbitrary shape. FIG. 1 shows a rectangular-structured secondary battery 5 as an example.

[0190] In some embodiments of the present application, as shown in FIG. 2, the exterior may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected on the bottom plate, and the bottom plate and the side plates enclose to form an accommodation cavity. The case 51 has an opening communicating with the accommodation cavity, and the cover plate 53 is used to cover the opening to seal the accommodation cavity. The positive electrode plate, the negative electrode plate, and the separator can form an electrode assembly 52 by a winding process and / or a lamination process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolyte is infiltrated into the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be adjusted according to demand.

[0191] The manufacturing method of the secondary battery of the present application is well-known. In some embodiments of the present application, a secondary battery can be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. As an example, the positive electrode plate, the separator, and the negative electrode plate can be formed into an electrode assembly through a winding process and / or a lamination process, the electrode assembly is placed in the exterior, and after drying, the electrolyte is injected, and through processes such as vacuum packaging, standing, chemical conversion, and shaping, a secondary battery is obtained.

[0192] In some embodiments of the present application, the secondary battery according to the present application can be assembled into a battery module, and the number of secondary batteries included in the battery module may be plural, and the specific number can be adjusted according to the application and capacity of the battery module.

[0193] FIG. 3 is a schematic diagram of a battery module as an example. As shown in FIG. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged and installed in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other way. Furthermore, these plurality of secondary batteries 5 may be fixed by fasteners.

[0194] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of secondary batteries 5 are accommodated in this accommodation space.

[0195] In some embodiments of the present application, the above battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0196] FIG. 4 and FIG. 5 are schematic diagrams of a battery pack 1 as an example. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any way.

[0197] Power consumption device A fourth embodiment of the present application provides a power consumption device comprising at least one of a secondary battery, battery module, or secondary battery pack as of the third embodiment of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The power consumption device may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0198] The power consumption device may be configured to use a secondary battery, battery module, or battery pack depending on its usage needs.

[0199] Figure 6 is a schematic diagram of an example power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of this power consumption device, a battery pack or battery module may be used.

[0200] Other examples of power-consuming devices include mobile phones, tablet computers, and laptop computers. These power-consuming devices generally require a thin design and can employ rechargeable batteries as their power source.

[0201] The embodiments described below provide a more detailed description of the content disclosed in this application, and these embodiments are for illustrative purposes only, as it will be obvious to those skilled in the art that various modifications and changes can be made within the scope of the content disclosed in this application. Unless otherwise stated, all parts, percentages and ratios reported in the embodiments below are based on mass, and all reagents used in the embodiments can be obtained commercially or synthesized according to conventional methods and can be used directly without further processing, and all instruments used in the embodiments can be obtained commercially.

[0202] Example 1 Manufacturing of silicone particles Preparation of prepolymer: 300 g of deionized water and 1.5 g of sodium dodecyl sulfate were added to 5 L three-necked flasks, and the mixture was emulsified by stirring at a rotation speed of 1500 r / min for 30 min to obtain a homogeneous and stable emulsion. Next, 137.74 g of methyl acrylate, 15.9 g of acrylonitrile, and 66.35 g of methacryloyloxypropyl cage-type polysilsesquioxane (the molar content ratio of methyl acrylate, acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane is 16:3:1) were added in order, and the mixture was stirred continuously at a rotation speed of 1500 r / min for 30 min to obtain a homogeneous prepolymer.

[0203] Silicone particle production: Add 0.6 g of sodium dodecyl sulfate and 200 g of deionized water to a dry three-necked flask and emulsify by stirring at high speed for 30 min to obtain a homogeneous and stable emulsion. Then, using a peristaltic pump, slowly add the prepolymer and initiator solution (formed by dissolving 0.6 g of potassium persulfate in 10 g of deionized water) prepared in the previous step, respectively, dropwise. After the dropwise addition is complete, raise the temperature to 90°C. The mixture was kept warm and reacted for 0.5 hours, then cooled to 40°C, the pH was adjusted to 7-8 with ammonia water, filtered, drained, and dried to produce silicone particles with a number-average molecular weight of 25473, which were recorded as O1. The water content of O1 was 1000 μg / g, the volume-distributed particle size Dv90 was 1.5 μm, the volume-distributed particle size Dv50 was 1.2 μm, the volume-distributed particle size Dv10 was 0.4 μm, and the specific surface area was 20 m². 2 It was / g.

[0204] Manufacturing of separators The PE substrate provided had a thickness of 6 μm and a porosity of 30%.

[0205] Preparation of coating slurry: Silicone particles O1 and polyvinyl alcohol were mixed in water in a ratio (mass ratio of 8:2) to prepare the coating slurry.

[0206] Coating: The prepared coating slurry was applied to both sides of the PE substrate using a coating machine, and a separator was obtained by drying and slitting.

[0207] Manufacturing of positive electrode plates The active material is LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), acetylene black (a conductive agent), and polyvinylidene fluoride (an adhesive) were uniformly mixed in an appropriate amount of solvent N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 to obtain a positive electrode slurry. This slurry was then applied to an aluminum foil positive electrode current collector, and a positive electrode plate was obtained through processes such as drying, cold pressing, slitting, and cutting.

[0208] Manufacturing of negative electrode plates 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 adhesive were uniformly mixed in an appropriate amount of deionized water as the solvent according to a mass ratio of 95:2:2:1 to obtain a negative electrode slurry. The negative electrode slurry was coated on a negative electrode current collector copper foil, and after undergoing drying, cold pressing, slitting, and cutting processes, a negative electrode plate was obtained.

[0209] Manufacturing of electrolyte Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 30:70 to obtain an organic solvent, and sufficiently dried LiPF6 was dissolved in the above organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0210] Battery cell manufacturing The positive electrode plate, separator, and negative electrode plate were stacked and wound in sequence to obtain an electrode assembly. The electrode assembly was placed in an outer package, and after drying, the electrolyte solution was added. After undergoing processes such as vacuum packaging, standing, formation, and shaping, a battery cell was obtained.

[0211] Examples 2 to 12 The battery cells were manufactured in a method similar to that of Example 1, and the difference lies in the parameters related to the coating of the separator. In Example 10, the type of silicone particles is different from that of other examples, and the details of the parameters are as shown in Table 1.

[0212] In Example 10, the manufacturing method of the silicone particles is as follows.

[0213] Preparation of prepolymer: 1400 g of deionized water and 7 g of sodium dodecyl sulfate were added to 5 L three-necked flasks, and the mixture was emulsified by stirring at a rotation speed of 1500 r / min for 30 min to obtain a homogeneous and stable emulsion. Next, 645.68 g of methyl acrylate, 75.59 g of acrylonitrile, and 663.50 g of methacryloyloxypropyl cage-type polysilsesquioxane (the molar content ratio of methyl acrylate, acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane is 15:3:2) were added in order, and the mixture was stirred continuously at a rotation speed of 1500 r / min for 30 min to obtain a homogeneous prepolymer.

[0214] Silicone particle production: Add 3 g of sodium dodecyl sulfate and 1000 g of deionized water to a dry three-necked flask and emulsify at high speed for 30 min to obtain a uniform and stable emulsion. Then, using a peristaltic pump, slowly add the prepolymer and initiator solution (3 g of potassium persulfate dissolved in 30 g of deionized water) prepared in the previous step dropwise. After the addition is complete, raise the temperature to 90°C and maintain the temperature for 0.5 hours to react, then cool to 40°C, adjust the pH to 7-8 with aqueous ammonia, filter, drain, and dry to produce silicone particles with a number-average molecular weight of 39529, which are recorded as O2. The water content of O2 is 1500 μg / g, the volume-distributed particle size Dv90 is 1.8 μm, the volume-distributed particle size Dv50 is 1.2 μm, the volume-distributed particle size Dv10 is 0.6 μm, and the specific surface area is 10 m². 2 It was / g.

[0215] Comparative Example 1 The battery cell was manufactured in a manner similar to that of Example 1, with the difference being parameters related to the separator coating, such as the particle material and M / (H·ρ 有機 The parameters are as shown in Table 1.

[0216] Test section (1) Heat shrinkage rate test of separator Sample manufacturing: The separators manufactured above are punched out in a press machine into samples measuring 50 mm in width and 100 mm in length. Five parallel samples are placed and fixed on an A4 sheet of paper. Then, the A4 sheet containing the samples is placed on a cardboard box with a thickness of 1 mm to 5 mm.

[0217] Sample test: Place an A4 sheet of paper on a cardboard box into a forced-air oven. Set the oven temperature to 150°C. After the temperature reaches the set temperature and stabilizes for 30 minutes, start timing. After 1 hour, measure the length and width of the separator and label the values ​​as a and b, respectively.

[0218] Calculation of thermal shrinkage rate: Longitudinal (MD) thermal shrinkage rate = [(100-a) / 100] × 100%, transverse (TD) thermal shrinkage rate = [(50-b) / 50] × 100%, the average value of five parallel samples is taken as the test result.

[0219] (2) Battery capacity retention rate test At 25°C, the battery is charged to 4.3V with a constant current of 1 / 3C, then charged again with a constant voltage of 4.3V until the current drops to 0.05C, left to stand for 5 minutes, and then discharged to 2.8V with 1 / 3C. The resulting capacity is denoted as the initial capacity C0. The discharge capacity C of the battery after 1000 cycles is then calculated. 1000 Simultaneously record the battery capacity retention rate P after each cycle. 1000 =C 1000 / C0*100%.

[0220] Table 1 lists the test results for different parameters of the coatings in Examples 1-12 and Comparative Example 1, respectively.

[0221] [Table 1]

[0222] As can be seen by comparing the test results of Examples 1-12 and Comparative Example 1 based on Table 1, the coating contains particulate organic material and the separator is M / (H×ρ 有機The condition )≧0.4 is satisfied, and on the one hand, the organic material can be rationally deposited in the coating, and when the separator is heated, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinkage direction of the separator, thereby reducing the degree of separator shrinkage, further reducing the risk of short circuits between the positive and negative electrodes in batteries using this separator, and enabling the battery to have good thermal safety performance. On the other hand, while rationally depositing the organic material in the coating, the contact between the organic materials can also form more ion transport channels, and these ion transport channels can enhance the infiltration of the electrolyte into the separator and storage within the separator, which is advantageous for ion transport and can improve the battery's cycle performance.

[0223] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are illustrative, and any embodiments that have substantially the same configuration as the technical idea and produce the same effects within the scope of the technical proposal of this application are included within the scope of the technical proposal of this application. Furthermore, other methods that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application. [Explanation of Symbols]

[0224] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module, 5: Battery cell, 51: Case, 52: Electrode assembly, 53: Cover plate.

Claims

1. A separator, Substrate and The substrate includes a coating provided on at least one side thereof, the coating comprising particulate organic material, Here, M is the weight per unit area of ​​the coating on one side, H is the thickness of the coating on one side, and ρ is the true density of the organic material. 有機 The separator is defined as M / (H×ρ 有機 ) ≥ 0.4 satisfies 1.4 ≤ H ≤ 2.1, where the unit of M is g / m ２ The unit of H is μm, and ρ 有機 The unit is g / cm ３ It is a separator.

2. 0.5 ≤ M / (H × ρ) 有機 The separator according to claim 1, wherein ) ≤ 0.

8.

3. ρ 有機 The separator according to claim 1, wherein the value is ≤ 2.

5.

4. The separator according to claim 1, wherein M ≥ 0.

5.

5. The separator according to claim 1, wherein 1.4 ≤ H ≤ 2.

0.

6. The separator according to claim 1, wherein M / H ≥ 0.

3.

7. The separator according to claim 1, wherein the mass ratio of the organic material in the coating is 60% or more.

8. The separator according to claim 1, wherein the organic material comprises one or more of the following: silicone particles, melamine formaldehyde resin particles, phenolic resin particles, polyester particles, polyimide particles, polyamide-imide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryletherketone particles.

9. The organic material comprises silicone particles, and the silicone particles comprise a first polymer, and the first polymer comprises a first structural unit, a second structural unit, and a third structural unit. The first structural unit has the structure shown in formula (I), 【Chemistry 1】 In equation (I), R １ This includes a hydrogen atom, or one or more substituted or unsubstituted C1-C5 alkyl groups. R ２ contains one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group, The second structural unit is as shown in formula (II), 【Chemistry 2】 In equation (II), R ３ This includes a hydrogen atom, or one or more substituted or unsubstituted C1-C5 alkyl groups. The third structural unit is as shown in formula (III), 【Transformation 3】 In equation (III), R ４ From R １１ Each independently comprises a substituted or unsubstituted C1-C10 alkyl group, or one or more of the structural units shown in formula (III-1), and R ４ From R １１ At least one of them is a structural unit shown in formula (III-1), 【Chemistry 4】 In equation (III-1), R １２ This includes a hydrogen atom, or one or more substituted or unsubstituted C1-C5 alkyl groups. R １３ The separator according to claim 1, comprising a substituted or unsubstituted C1-C10 alkyl group.

10. Based on the total molar amounts of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, and 70 ≤ a ≤ 90, and / or Based on the total molar amounts of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is denoted as b%, where 0 < b ≤ 18, and / or The separator according to claim 9, wherein the molar content of the third structural unit is denoted as c%, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and 0 < c ≤ 15.

11. Based on the total molar amounts of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, the molar content of the second structural unit is denoted as b%, and the molar content of the third structural unit is denoted as c%, and the silicone particles are as follows: (1) The condition that 5 ≤ a / b ≤ 10, (2) The condition that 6 ≤ a / c ≤ 15, (3) The separator according to claim 9, which satisfies one or more of the conditions that a:b:c is (14-16):(3-4):(1-4).

12. The organic material comprises silicone particles, and the silicone particles comprise a second polymer, and the second polymer comprises structural units shown in formula (a). 【Transformation 5】 In equation (a), R １４ and R １５ The separator according to claim 1, wherein each is independently selected from substituted or unsubstituted C1-C10 alkyl groups, hydroxyl groups, or amino groups.

13. The separator according to claim 9, wherein the number-average molecular weight of the silicone particles is 25,000 to 60,000.

14. The separator according to claim 9, wherein the water content of the silicone particles is 3000 μg / g or less, based on the mass of the silicone particles.

15. The volume distribution particle size Dv90 of the silicone particles satisfies the condition Dv90 ≤ 4.0 μm. The volume distribution particle size Dv50 of the silicone particles satisfies 1.0 μm ≤ Dv50 ≤ 2.5 μm. The particle size distribution of the silicone particles is 0.5 ≤ (D Ｖ 90-D Ｖ 10) / D Ｖ A separator according to claim 9, satisfying 50 ≤ 1.

5.

16. The specific surface area of ​​the aforementioned silicone particles is 35 m². ２ The separator according to claim 9, wherein the amount is less than or equal to / g.

17. The thickness of the substrate is 12 μm or less, and / or The separator according to claim 1, wherein the substrate has a porous structure, and the porosity of the substrate is 20% or more.

18. The aforementioned separator is, (1) The separator has the characteristic that its longitudinal thermal shrinkage rate at 150°C for 1 hour is 3% or less, (2) The separator has the characteristic that its lateral thermal shrinkage rate at 150°C for 1 hour is 2% or less, (3) The separator has the characteristic of having an air permeability of 200 s / 100 mL or less, (4) The longitudinal tensile strength of the separator is 2700 kgf / cm ２ The above are the characteristics and (5) The lateral tensile strength of the separator is 2500 kgf / cm ２ The separator according to claim 1, which satisfies at least one of the above characteristics.

19. The steps include providing a substrate and The process involves mixing particulate organic material with a solvent to prepare a coating slurry, The process includes the steps of applying the coating slurry to at least one side of the substrate to form a slurry film layer, drying the film layer to form a coating, and obtaining a separator. Here, M is the weight per unit area of ​​the coating on one side, H is the thickness of the coating on one side, and ρ is the true density of the organic material. 有機 The separator is defined as M / (H×ρ 有機 ) ≥ 0.4 satisfies 1.4 ≤ H ≤ 2.1, where the unit of M is g / m ２ The unit of H is μm, and ρ 有機 The unit is g / cm ３ The method for manufacturing a separator according to any one of claims 1 to 18.

20. A secondary battery comprising a separator according to any one of claims 1 to 18.

21. A power consumption device comprising a secondary battery as described in claim 20.

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