Separator and method for manufacturing the same, 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 a separator and a method for manufacturing the same, a secondary battery, and a power consumption device.

Background Art

[0002] Batteries have characteristics such as good electrochemical performance and safety performance, and thus are widely applied in many fields such as power tools, electric vehicles, aerospace, and energy storage devices. With the popularization and application of batteries in many fields, their thermal safety performance and cycle performance have become two focuses of attention in battery performance.

[0003] Currently, the thermal safety performance of batteries still has the defect of decreasing when heated, and its cycle performance may also decrease. Therefore, it is necessary to improve the thermal safety performance and cycle performance of batteries.

Summary of the Invention

[0004] The purpose of this application is to provide a separator and a method for manufacturing the same, a secondary battery, and a power consumption device. This separator has characteristics 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] The first aspect of this application provides a separator, which includes a base material and a coating provided on at least one side of the base material. The coating includes a particulate organic material. Denote the weight per unit area of the one-sided coating as M, the thickness of the one-sided coating as H, and the true density of the organic material as ρ 有機 Denote it as ρ. 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 .

[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 ), 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 direction opposite to the shrinking direction of the separator, reduce the degree of shrinkage of the separator, and further reduce the short-circuit risk 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 on 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 at the same time giving the battery good thermal safety performance and further improving the cycle performance of the battery.

[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 the weight reduction of the battery using this separator, and thus improve 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 the present application, M ≥ 0.5. The weight per unit area of the single-sided coating satisfies the above relationship, and further, the organic materials in the coating can be deposited more closely, and the adjacent organic materials can be integrally abutted. When the separator receives heat, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinking direction of the separator, further reducing the degree of shrinkage of the separator, thereby reducing the occurrence of short circuits between the positive electrode plate and the negative electrode plate.

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

[0012] In any embodiment of the present application, H ≤ 3.0. By satisfying the above relationship for the thickness H of the single-sided coating, it can contribute to the close deposition between the organic materials and further improve the thermal safety performance of the battery.

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

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

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

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

[0017] In any embodiment of the present application, the organic material includes one or more of silicone particles, melamine formaldehyde resin particles, phenol resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramide particles, polyphenylene sulfide particles, polysulfone particles, polyether sulfone particles, polyether ether ketone particles, and polyaryl ether ketone particles. Optionally, the organic material includes silicone particles.

[0018] In any embodiment of the present application, the organic material includes silicone particles, the silicone particles include a first polymer, and the first polymer includes a first structural unit, a second structural unit, and a third structural unit. The first structural unit has a structure represented by formula (I).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0019] In any embodiment of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, and 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%, and 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%, and 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%, and 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) a condition that 5 ≦ a / b ≦ 10, (2) a condition that 6 ≦ a / c ≦ 15, (3) a 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 one embodiment of the present application, the number average molecular weight of the silicone particles is 25,000 to 60,000, and optionally 30,000 to 50,000. When the number average molecular weight of the silicone particles is within this range, it is advantageous to form silicone particles with a relatively small particle size, which, when applied to a separator, can achieve a light and thin coating on the separator, reducing the overall thickness of the separator and thereby helping to improve the energy density of the battery, as well as reducing the risk of the silicone particles clogging the substrate in the separator, thereby achieving the goal of improving the performance of the separator as a whole, such as its air permeability.

[0023] In any embodiment of the present application, the moisture content of the silicone particles may be 3000 μg / g or less, and optionally 700 μg / g to 2500 μg / g, based on the mass of the silicone particles.

[0024] In one embodiment of the present 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 this appropriate range, the deposition density can be improved, and the coating can have an appropriate thickness, thereby improving the energy density of the battery.

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

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

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

[0028] In any embodiment of the present application, the specific surface area of the silicone particles is 35 m 2 / g or less, and optionally 5 m 2 / g to 30 m 2 / 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, and further contribute to the improvement of the infiltration effect and the liquid retention effect of the electrolyte on the separator.

[0029] In any embodiment of the present application, the thickness of the base material is 12 μm or less.

[0030] In any embodiment of the present application, the thickness of the base material is 3 μm to 8 μm.

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

[0032] In any embodiment of the present application, the porosity of the base material is 25% to 45%.

[0033] In any embodiment of the present application, the longitudinal thermal shrinkage rate of the separator at 150 °C for 1 h is 3% or less.

[0034] In any embodiment of the present application, the transverse thermal shrinkage rate of the separator at 150 °C for 1 h is 2% or less.

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

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

[0037] In any embodiment of the present application, the longitudinal tensile strength of the separator is 2700 kgf / cm 2 or more.

[0038] In any embodiment of the present application, the transverse tensile strength of the separator is 2500 kgf / cm 2 or more.

[0039] The second aspect of the present application provides a method for manufacturing the separator according to the first aspect of the present application. This manufacturing method includes a step of providing a base material, a step of mixing particulate organic material with a solvent to prepare a coating slurry, a step of applying the coating slurry to at least one side of the base material to form a slurry film layer, and drying the slurry film layer to form a coating, thereby obtaining a separator, wherein the weight per unit area of the single-sided coating is denoted as M, the thickness of the single-sided coating is denoted as H, the true density of the organic material is denoted as ρ 有機 and 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 .

[0040] The third aspect of the present application provides a secondary battery, which includes the separator according to the first aspect of the present application or the separator manufactured by the method according to the second aspect of the present application.

[0041] The fourth aspect of the present application provides a power consumption device, which includes the secondary battery according to the third aspect of the present application.

Brief Description of the Drawings

[0042] To more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on the drawings on the premise of not paying creative labor.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0043] In the drawings, the drawings are not necessarily drawn to actual scale.

Embodiments for Carrying out the Invention

[0044] Hereinafter, with appropriate reference to the drawings, the separator of the present application, its manufacturing method, and the embodiments specifically disclosing the secondary battery and the power consumption device will be described in detail. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily redundant and to make it easily understood by those skilled in the art. It should be noted that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the theme described in the claims.

[0045] The "ranges" disclosed in this application are limited in the form of a lower limit and an upper limit. A given range is limited by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The ranges thus defined may or may not include the limit values, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it is understood that ranges of 60 - 110 and 80 - 120 are also conceivable. In addition, if 1 and 2 are listed as the minimum range values and 3, 4, and 5 are listed as the maximum range values, ranges of 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5 are all conceivable. In this application, unless otherwise specified, the numerical range "a - b" represents a shortened expression of any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0 - 5" represents that all real numbers between "0 - 5" have already been listed in this specification, and "0 - 5" is only a shortened expression of the combinations of these numerical values. Also, when a certain parameter is expressed as an integer greater than or equal to 2, it is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of this application.

[0047] Unless otherwise specified, all technical features and alternative technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of this application.

[0048] Unless otherwise specified, all steps of this application may be performed in order or randomly, and preferably, they are performed in order. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, the fact that the method mentioned 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), etc.

[0049] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application may represent an open type or a closed type. For example, the "comprising" and "including" may further comprise or include other components not listed, or may comprise or include only the listed components.

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

[0051] In this application, terms such as "first", "second", etc. are used only for the purpose of description and should not be understood as indicating or implying relative importance.

[0052] In this application, the terms "a plurality of" and "various" mean two or more.

[0053] Unless otherwise stated, the terms used in this application have the meanings known to those skilled in the art and are generally understood.

[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 provided 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 installed between the positive electrode plate and the negative electrode plate, mainly functioning to prevent short circuit between the positive and negative electrodes, and at the same time, allowing active ions to pass freely to form a circuit.

[0056] Due to the characteristics such as good electrochemical performance and safety performance, batteries are widely applied in many fields such as power tools, electric vehicles, aerospace, and energy storage devices. With the popularization and application of batteries in many fields, their thermal safety performance and cycle performance have become two focuses of attention in battery performance.

[0057] The separator is an important part for improving the thermal safety performance and cycle performance of the battery. The separators used in currently commercialized batteries are generally polyolefin porous membranes. Due to their relatively low melting points, significant heat shrinkage effects occur when heated, which not only reduces the ion transport channels, but also causes a decrease in ion conductivity, further increasing the internal resistance of the battery and reducing the cycle performance of the battery. In addition, the shrinkage of the separator causes the positive and negative electrodes inside the battery to come into direct contact, resulting in 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 characteristics such as good heat resistance and ion transport characteristics, thereby improving the thermal safety performance and cycle performance of the battery using this separator.

[0059] Separator The first aspect of the present application provides a separator, which includes a substrate and a coating disposed on at least one side of the substrate. The coating includes a particulate organic material. Denote the weight per unit area of the one-sided coating as M, the thickness of the one-sided coating as H, and the true density of the organic material as ρ 有機 Denote it as such. 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 .

[0060] In the separator according to the present application, the coating includes a particulate organic material, and the separator satisfies M / (H×ρ 有機 )≧0.4. On the one hand, the organic material in the coating can be reasonably deposited. 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 short-circuit risk between the positive and negative electrodes in the battery using this separator, enabling the battery to have good thermal safety performance. On the other hand, while reasonably depositing the organic material on 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.

[0061] In some embodiments of the present application, the separator satisfies 0.5≦M / (H×ρ 有機 )≦0.8. By the separator satisfying the above relationship, the organic material can be deposited more tightly on the coating, further reducing the degree of shrinkage of the separator, and further enabling the battery to have good thermal safety performance while further improving the cycle performance of the battery.

[0062] Exemplarily, M / (H×ρ 有機) may be in the range of 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 or a range consisting of any two of the above numerical values, but is not limited thereto. Optionally, M / (H×ρ 有機 ) The value range of may be 0.4 - 0.8, 0.45 - 0.75, 0.5 - 0.7, 0.55 - 0.7 or 0.6 - 0.7.

[0063] In some embodiments of the present application, the true density ρ of the organic material 有機 is ρ 有機 satisfies ρ ≦2.5. By setting the true density of the organic material within the above appropriate range, it is possible to contribute to reducing the weight of the battery using this separator, and thus to improve the mass energy density of the battery.

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

[0065] In some examples, the true density ρ of the organic material 有機 may be in the range of 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 a range consisting of any two of the above numerical values, but is not limited thereto. Optionally, it is 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 the organic material is a known meaning in the art and can be measured by known methods in the art. For example, it can be tested with reference to GB / T 24586, and specifically the following steps can be referred to. Place a clean and dry sample cup on the balance, zero it, add the powder sample to the sample cup, which occupies about 1 / 2 of the volume of the sample cup, record the mass of the sample, place the sample cup containing the sample on the true density tester, seal the test system, introduce helium gas according to the procedure, detect the pressure of the gas in the sample chamber and the expansion chamber, and further calculate the true volume based on Boyle's law (PV=nRT), thereby calculating the true density.

[0067] In some embodiments of the present application, the weight M per unit area of the single-sided coating satisfies M≧0.5. The weight per unit area of the single-sided coating satisfies the above relationship, and the organic materials in the coating can be deposited more tightly, and the adjacent organic materials can be brought into contact with each other integrally. When the separator receives heat, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the contraction direction of the separator, further reducing the degree of contraction of the separator, thereby reducing the occurrence of short circuits between the positive electrode plate and the negative electrode plate.

[0068] In some other embodiments of the present 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 a range consisting of any two of the above numerical values, but not limited thereto. 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 the one-sided coating is a meaning known in the art and can be measured using methods known in this field. For example, it can be tested according to the following steps. Take a separator sample, punch it into a small disc with an area of S1, weigh its weight, and record it as M1. Next, remove the coating of the sample after the above weighing, weigh the weight of 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 one-sided coating = (M1 - M0) / S1, (2) When the substrate has coatings on both sides, the weight per unit area of the one-sided coating = (M1 - M0) / S1 / 2, In some embodiments of the present application, the thickness H of the one-sided coating satisfies H ≤ 3.0. The thickness H of the one-sided coating satisfies the above relationship and can contribute to the close deposition between organic materials. Thus, when the separator receives heat, the close deposition between organic materials can quickly provide a force acting in the opposite direction to the shrinking direction of the separator, further reducing the degree of shrinkage of the separator and reducing the occurrence of short circuits between the positive electrode plate and the negative electrode plate, thereby achieving the purpose of improving the thermal safety performance of the battery.

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

[0072] In some examples, the thickness H of the coating 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 numerical values, but not limited thereto. 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, 1.0 - 2.0.

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

[0074] In some embodiments of the present application, the weight M per unit area of the single-sided coating and the thickness H of the single-sided coating satisfy M / H≧0.3.

[0075] In some embodiments of the present application, the weight M per unit area of the single-sided coating and the thickness H of the single-sided coating satisfy 0.5≦M / H≦1.0.

[0076] It should be noted that each coating parameter (such as thickness, weight per unit area, etc.) given in the present application refers to the coating parameter of one side. When the coating is installed on both sides of the substrate simultaneously, if the coating parameter of either side satisfies the present application, it is considered to fall within the protection scope of the present application.

[0077] In some embodiments of the present application, the organic material includes one or more of silicone particles, melamine formaldehyde resin particles, phenol resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramide particles, polyphenylene sulfide particles, polysulfone particles, polyether sulfone particles, polyether ether ketone particles, and polyaryl ether ketone particles.

[0078] In some alternative embodiments of the present application, the organic material includes silicone particles. These silicone particles refer to organosiloxanes with a silicon bond (-Si-O-Si-) in the main chain. Since the silicon bond is an inorganic bond, the bonding energy is relatively large, and high heat resistance and chemical stability can be imparted to the silicone. For example, silicone can be used for a long time at temperatures below 200°C. The side chains of the silicone may or may not be grafted with other groups. When grafted with organic groups, good dispersibility and the like can be imparted to the silicone, improving the coating performance of the silicone coating and the affinity with the substrate. When the silicone particles are dispersed in the coating, the separator has good heat resistance, thereby improving the thermal safety performance of the secondary battery. Also, a structure with voids between the silicone particles can be formed, further improving the infiltration and retention characteristics of the separator with respect to the electrolyte solution, thereby promoting the transport of active ions in the separator, and when the separator is applied to a secondary battery, the cycle performance of the secondary battery can be improved.

[0079] In some embodiments of the present application, the silicone particles include a first polymer, and the first polymer includes 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),

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0081] In the above embodiments, 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 exertion of good adhesion. The second structural unit can generate excellent swelling resistance and high adhesiveness. Further, when the first polymer is applied to the separator, the first polymer contacts the electrolyte, and the first polymer is difficult to swell, which has relatively excellent swelling resistance. The third structural unit includes a framework structure composed of Si-O-Si or Si-O bonds, which can endow the first polymer with advantages in terms of heat resistance and mechanical properties. Further, in the long-term cycle charge and discharge process of the battery, the separator can have good thermal stability, effectively isolate the positive and negative electrode plates, and thereby guarantee the thermal safety performance of the battery.

[0082] In addition, the first structural unit and the third structural unit cooperate to exert a synergistic effect, which can improve the adhesiveness and heat resistance of the first polymer. The first structural unit and the second structural unit cooperate to exert a synergistic effect, which can improve the swelling resistance of the first polymer, etc. Therefore, the first polymer can not only improve the adhesion between the coating and the substrate, but also enhance the heat resistance of the separator to improve the thermal safety performance of the battery.

[0083] In some embodiments of the present application, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, and 70 ≦ a ≦ 90. When the molar content of the first structural unit is within the above range, the adhesiveness of the first polymer can be significantly improved. When the first polymer is applied to the separator, the bonding force between the first polymer and the substrate of the separator can be improved. Optionally, 75 ≦ a ≦ 85. Exemplarily, the molar content of the first structural unit may be 70%, 75%, 80%, 85%, 90%, or a range consisting of any two of the above numerical values.

[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 adhesiveness 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 adhesiveness 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 adhesiveness 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 adhesiveness 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 heat resistance is relatively poor. When the first polymer is applied to a separator, as the charge and discharge time of the battery increases, the temperature inside the battery rises, which may cause the destruction of the first structural unit. The first polymer further includes a third structural unit. The inorganic structure of polysilsesquioxane in the third structural unit synergistically acts with the first structural unit, and can improve the heat resistance and adhesion of the entire 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 can be exerted between the first structural unit and the third structural unit, and the adhesion and heat resistance of the first polymer can be improved. Exemplarily, a / c may be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a range consisting of any two of the above numerical values.

[0088] In some embodiments of the present application, the degree of polymerization a of the first structural unit, the degree of polymerization b of the second structural unit, and the degree of polymerization c of the third structural unit satisfy a:b:c = (14 - 16):(3 - 4):(1 - 4). When the degrees of polymerization of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratio, the three types of structural units in the silicone particles can exert their respective performance advantages, and the three types of structural units can cooperate with each other to improve the adhesion, thermal stability, and swelling resistance of the polymer together.

[0089] The first structural unit includes a plurality of chemical structures. Next, the specific chemical structure of the first structural unit will be described.

[0090] In some embodiments of the present application, R1 includes a hydrogen atom and / or a methyl group.

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

[0092] Exemplarily, the first structural unit includes one or more of the structures shown by formula (I-1) to formula (I-8),

Chemical formula

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

[0094] In some embodiments of the present application, R3 includes a hydrogen atom and / or a methyl group.

[0095] Exemplarily, the second structural unit includes one or more of the structures shown by formula (II-1) to formula (II-4),

Chemical formula

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

[0097] In some embodiments of the present application, R4 to R 11 each independently includes a structural unit shown by formula (III-1), and optionally, R 12 is 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 is one or more of an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group.

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

[0099] In some embodiments of this application, the infrared spectrum of the first polymer has characteristic peaks from 1750 cm -1 to 1735 cm -1 indicating the presence of ester groups.

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

[0101] In some embodiments of this application, the infrared spectrum of the first polymer has characteristic peaks from 1100 cm -1 to 1120 cm -1 indicating the presence of the Si-O-Si framework of silsesquioxane.

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

[0103] This application performs copolymerization after mixing the first monomer, the second monomer, and the third monomer, and the formed first polymer is a copolymer of the three types of monomers.

[0104] The first monomer has a structure represented by formula (IV),

Chemical formula

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

[0106] Exemplarily, 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 a structure represented by formula (V),

Chemical formula

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

[0109] Exemplarily, the second monomer contains acrylonitrile and / or methacrylonitrile.

[0110] The third monomer shown has the structure shown in formula (VI),

Chemical formula

Chemical formula

[0111] Exemplarily, the third monomer includes one or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacryloyloxypropyl heptaisobutyl polysilsesquioxane, acryloyloxypropyl cage-type polysilsesquioxane, acryloyloxypropyl heptaisobutyl polysilsesquioxane, and methacryloyloxypropyl heptaoctyl polysilsesquioxane.

[0112] In some embodiments of the present application, step S200 specifically Step S210 of adding the first monomer, the second monomer, and the third monomer to a solvent and an emulsifier and mixing them to form a mixed system; Step S220 of adding an initiator to the mixed system and generating a polymerization reaction by the action of the initiator to produce a first polymer.

[0113] The present application may perform copolymerization of a plurality of types of monomers by an emulsion polymerization method, and the polymerization method is simpler. Of course, the present application may further use other polymerization means, such as solution polymerization, suspension polymerization, etc. The process parameters used in the polymerization process may be selected from general parameters in this field and will not be further described here.

[0114] In some embodiments of the present application, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, alkyl group diphenyloxide disulfonate, and ethoxylated alkyl group phenol ammonium sulfate.

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

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

[0117] In some embodiments of the present application, based on the total mass of the mixture system, the ratio of the mass percentage content of the initiator to the mass percentage contents of the first monomer, the second monomer, and the third monomer is from 0.15% to 1%, that is, the usage amount of the initiator is from 0.1% to 5% of the mass of the three types of monomers. When the mass percentage content of the initiator is within the above range, sufficient polymerization can be guaranteed.

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

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

[0120] Manufacture of prepolymer: After mixing deionized water, an emulsifier, a first polymerization monomer, a second polymerization monomer, and a third polymerization monomer and stirring uniformly, a prepolymer is obtained. Manufacture of the first polymer: Add an emulsifier and deionized water to a container, stir for 30 min to 60 min for emulsification to obtain a uniform and stable emulsion. Next, slowly dropwise add the prepolymer produced in the previous step and the initiator solution (dissolve potassium persulfate and / or ammonium persulfate of the initiator in deionized water to form a solution) respectively. After the dropping is completed, raise the temperature to 90°C to 110°C and keep warm for 0.5 h for reaction, then cool to 40°C. After adjusting the pH to 7 to 8 with ammonia water, filter, discharge, and obtain the polymer through a drying process.

[0121] In some embodiments of the present application, the silicone particles contain a second polymer, and the second polymer contains a structural unit represented by formula (a).

Chemical formula

[0122] Exemplarily, the silicone particles contain at least one of the structures represented by formula (a-1) to formula (a-5), [Chemical formula]

[0123] The first polymer and the second polymer in this application are only used for distinguishing the types of materials, and have no limiting effect on the order and quantity.

[0124] In some embodiments of this application, the number average molecular weight of the silicone particles is 25,000 to 60,000, and optionally 30,000 to 50,000. Exemplarily, the number average molecular weight of the silicone particles may be 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000 or a range composed of any two of the above numerical values. When the number average molecular weight of the silicone particles is within the above range, it has a relatively high viscosity. When the silicone particles are applied to the separator, it is advantageous to improve the adhesion between the separator and the positive and negative electrode plates. When the number average molecular weight of the silicone particles is within the above range, it is advantageous for the formation of silicone particles with a relatively small particle size. When applied to the separator, it can achieve a thin coating on the separator, reduce the overall thickness of the separator, thereby contributing to the improvement of the energy density of the secondary battery, and the particle size of the silicone particles formed by the silicone particles is not too small, reducing the risk of the silicone particles blocking the base material in the separator, and improving the performance such as the air permeability of the whole separator.

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

[0126] The inventor further studied and found that during the long-term charge-discharge process of the battery, the moisture in the separator is gradually released into the electrolyte. The electrolyte has high sensitivity to moisture and is likely to generate hydrofluoric acid HF when contacting water, thereby increasing the acidity of the electrolyte, causing corrosion of the active material, current collector, etc., and also causing elution of transition metal ions in the active material, which may affect the electrochemical performance of the battery. Therefore, in this application, the moisture content of the silicone particles is adjusted to 3000 μg / g or less, selectively adjusted to 700 μg / g to 2500 μg / g, and calculated based on the mass of the silicone particles. When the moisture content of the silicone particles is within the above range, the moisture content contained therein is relatively small, reducing the risk of side reactions of the electrolyte during the long-term charge-discharge cycle of the battery, thereby improving the electrochemical performance of the battery. Exemplarily, the moisture content of the silicone particles may be 700 μg / g, 800 μg / g, 1000 μg / g, 1200 μg / g, 1500 μg / g, 1800 μg / g, 2000 μg / g, 2500 μg / g, 3000 μg / g, or a range consisting of any two of the above numerical values.

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

[0128] In some embodiments of the present 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 bulk density thereof can be improved, and an appropriate thickness can be provided for the coating to improve the energy density of the battery.

[0129] In some other embodiments of the present 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 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 a range consisting of any two of the above numerical values, but is not limited thereto.

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

[0132] In the present application, the volume distribution particle size Dv90 of the material has the meaning known in the art, which represents the particle size corresponding when the cumulative volume distribution percentage of the material reaches 90%, and can be measured using known instruments and methods in the art. For example, referring to GB / T 19077 - 2016 Laser Diffraction Method for Particle Size Distribution, it can be measured using a laser particle size analyzer (such as Master Size 3000).

[0133] In this application, the volume distribution particle size Dv50 of the material has the well-known meaning in the art, which represents the particle size corresponding when the cumulative volume distribution percentage of the material reaches 50%, and can be measured using known instruments and methods in the art. For example, referring to GB / T 19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be measured using a laser particle size analyzer (such as Master Size 3000).

[0134] In this application, the volume distribution particle size Dv10 of the material has the well-known meaning in the art, which represents the particle size corresponding when the cumulative volume distribution percentage of the material reaches 10%, and can be measured using known instruments and methods in the art. For example, referring to GB / T 19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be measured using a laser particle size analyzer (such as Master Size 3000).

[0135] In some embodiments of this application, the specific surface area of the silicone particles is 35 m 2 / g or less, and optionally 5 m 2 / g to 30 m 2 / 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, which further contributes to the improvement of the infiltration effect and liquid retention effect of the electrolyte on the separator.

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

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

[0138] In some embodiments of the present application, the thickness of the base material is 12 μm or less. Optionally, the thickness of the base material is 3 μm to 8 μm. Since the coating of the present application can improve the thermal safety performance and cycle performance of the separator, a thinner base material can be selected, thereby contributing to further improving the energy density of the battery.

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

[0140] The present application does not particularly limit the material of the base material, and any known base material with good chemical stability and mechanical stability can be selected. For example, the base material may include at least one of a porous polyolefin-based resin film (such as at least one of polyethylene, polypropylene, and polyvinylidene fluoride), porous glass fiber, and porous non-woven fabric. The porous base material may be a single-layer film or a multi-layer composite film. When the porous base material is a multi-layer composite film, the materials of each layer may be the same or different.

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

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

[0143] In the above embodiments, since the separator of the present application has a low thermal shrinkage rate in both the transverse and longitudinal directions, the thermal safety performance of the battery can be further improved.

[0144] In some embodiments of the present application, the air permeability of the separator is 200 s / 100 mL or less. Optionally, the air permeability of the separator is 150 s / 100 mL to 200 s / 100 mL. The separator of the present application has good air permeability, which can improve the ion transport characteristics, reduce the resistance of the battery, and improve the cycle performance of the battery.

[0145] In some embodiments of the present application, the longitudinal tensile strength of the separator is 2700 kgf / cm 2 or more.

[0146] In some embodiments of the present application, the transverse tensile strength of the separator is 2500 kgf / cm 2 or more.

[0147] In the above embodiments, the separator of the present application has high tensile strength in both the transverse and longitudinal directions. When the battery expands, the probability of the separator being damaged is relatively low, and the safety performance of the battery can be further improved.

[0148] In the present 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 them may be tested with reference to the standard GB / T 36363-2018.

[0149] It should be noted that the above coating parameters of the separator are all the coating parameters on one side of the substrate.

[0150] When the coating is installed on both sides of the substrate, if the coating parameters on any one side meet the present application, it is considered to be within the protection scope of the present application.

[0151] Manufacturing method of separator The second aspect of the present application provides a method for manufacturing a separator according to the first aspect of the present application. In S1, a step of providing a base material is included. In S2, a particulate organic material is mixed with a solvent to prepare a coating slurry. In S3, the coating slurry is applied to at least one side of the base material to form a slurry film layer, and the slurry film layer is dried to form a coating, thereby obtaining a separator. Here, the weight per unit area of the single-sided coating is denoted as M, the thickness of the single-sided coating is denoted as H, and the true density of the organic material is denoted as ρ 有機 and the separator satisfies M / (H×ρ 有機 )≧0.4. Here, 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 .

[0152] In some embodiments of the present application, in S2, the solvent may be water, for example, deionized water. The adhesive may be an aqueous solution type adhesive, which has the advantages of high thermodynamic stability and environmental friendliness, and is thus advantageous for the manufacture and application of the coating slurry. As an example, the aqueous solution type adhesive may include at least one of an aqueous solution type acrylic resin (for example, a copolymer of acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or other copolymer monomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer, and polyacrylamide. Further, the coating slurry may further include other components, such as a dispersant, a wetting agent, and the like.

[0153] In some embodiments of the present application, in S3, a coater is employed for the application. The present application does not particularly limit the model number of the coater, and for example, a commercially available coater may be employed. Optionally, the coater includes a gravure roller, and the gravure roller is used to transfer the coating slurry onto the base material. Optionally, the number of lines of the gravure roller is 100 LPI to 200 LPI, and more optionally 150 LPI to 180 LPI. Also, application methods such as transfer coating, rotary spray coating, dip coating, etc. may be used.

[0154] In some embodiments of the present 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, the film surface problem of the coating can be effectively reduced, and the occurrence probability of coating non-uniformity can be reduced, thereby further improving the energy density and safety performance of the battery.

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

[0156] The manufacturing method of the separator of the present application obtains the coating by one-time coating, which greatly simplifies the manufacturing process flow of the separator.

[0157] Parameters such as some raw materials used in the manufacturing method of the separator of the present application and their contents can refer to the separator of the first aspect of the embodiments of the present application, and will not be described further here. Unless otherwise specified, each raw material used in the manufacturing method of the separator of the present application can be obtained by purchasing commercially available products.

[0158] Secondary battery The third aspect of the embodiments of the present application provides a secondary battery. A secondary battery is also called a rechargeable battery or a storage battery, and is a battery that can continue to be used by activating the active material in a charging manner after the battery discharges. 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 installed between the positive electrode plate and the negative electrode plate, and mainly functions to prevent short circuit between the positive electrode and the negative electrode, and can allow active ions to pass through.

[0159] This application is not particularly limited to the type of secondary battery. For example, the secondary battery may be a lithium-ion battery, a sodium-ion battery, etc. In particular, the secondary battery may be a lithium-ion secondary battery.

[0160] The secondary battery of this application includes the separator of the first aspect of this application or the separator obtained by the manufacturing method of the second aspect of this application, and the separator is interposed between the positive electrode plate and the negative electrode plate. Optionally, at least one side of the separator close to the negative electrode plate has the coating of this application. Thereby, the secondary battery of this application has relatively excellent 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 a positive electrode active material. For example, the positive electrode current collector has both sides facing each other in its thickness direction, and the positive electrode film layer is provided on either one or both of the two opposing surfaces of the positive electrode current collector.

[0162] When 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 manganese iron phosphate, a composite material of lithium manganese iron 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] For 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, cathode active materials used in sodium-ion secondary batteries include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, materials of which the general formula is X p M’ q (PO4) r O x Y 3-x and may include at least one of them. In the general formula X p M’ q (PO4) r O x Y 3-x , 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, X is selected from at least one of H + , Li + , Na + , K + and NH4 + , M’ is a transition metal cation and is selectively at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halogen anion and is selectively at least one of F, Cl and Br.

[0167] In this application, the modified compounds of the above cathode active materials perform doping modification and / or surface coating modification on the cathode active materials.

[0168] In some embodiments of the present application, the positive electrode film layer selectively further contains a positive electrode conductive agent. The present application is not particularly limited to the type of the positive electrode conductive agent. For example, the positive electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments of the present application, based on the total weight of the positive electrode film layer, the mass percentage content of the positive electrode conductive agent is ≤6 wt%.

[0169] In some embodiments of the present application, the positive electrode film layer selectively further contains a positive electrode adhesive. The present application is not particularly limited to the type of the positive electrode adhesive. For example, the positive electrode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In some embodiments of the present application, based on the total weight of the positive electrode film layer, the mass percentage content of the positive electrode adhesive is ≤5 wt%.

[0170] In some embodiments of the present application, a metal foil sheet or a composite current collector may be employed for the positive electrode current collector. As an example of the metal foil sheet, an aluminum foil can be employed. 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 aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. 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).

[0171] The positive electrode film layer is generally obtained by applying 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 uniformly stirring them. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

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

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

[0174] In some embodiments of the present application, the negative electrode film layer further selectively includes a negative electrode conductive agent. The present application is not particularly limited with respect to the type of the negative electrode conductive agent. By way of example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments of the present application, based on the total weight of the negative electrode film layer, the mass percentage content of the negative electrode conductive agent is ≤ 7 wt%.

[0175] In some embodiments of the present application, the negative electrode film layer optionally further contains a negative electrode binder. The present application is not particularly limited with respect to the type of the negative electrode binder. For example, the negative electrode binder may contain at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (for example, polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments of the present application, based on the total weight of the negative electrode film layer, the mass percentage content of the negative electrode binder is ≤6 wt%.

[0176] In some embodiments of the present application, the negative electrode film layer optionally further contains other auxiliaries. For example, the other auxiliaries may include a thickener, such as sodium carboxymethyl cellulose (CMC), PTC thermistor material, and the like. In some embodiments of the present application, based on the total weight of the negative electrode film layer, the mass percentage content of the other auxiliaries is ≤3 wt%.

[0177] In some embodiments of the present application, a metal foil sheet or a composite current collector may be employed as the negative electrode current collector. As an example of the metal foil sheet, a copper foil can be employed. 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 alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. 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 applying 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 auxiliaries in a solvent and uniformly stirring them. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

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

[0180] [Electrolyte solution] During the charge and discharge process of the secondary battery, active ions reciprocate between the positive electrode plate and the negative electrode plate for insertion and deinsertion, and the electrolyte solution serves to conduct the active ions between the positive electrode plate and the negative electrode plate. The present application does not particularly limit the type of the electrolyte solution, and it can be selected according to actual needs.

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

[0182] When the secondary battery of the present application is a lithium-ion secondary battery, for example, the electrolyte salt may include at least one of lithium hexafluorophosphate (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] When the secondary battery of the present application is a sodium-ion secondary battery, for example, the electrolyte salt may include at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (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] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4 - butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0185] In some embodiments of the present application, the electrolyte may further selectively contain additives. For example, the additives may include a negative electrode film - forming additive, a positive electrode film - forming additive, and additives that can improve some performances 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, additives that improve the low - temperature power performance of the secondary battery, and the like.

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

[0187] In some embodiments of the present application, the secondary battery may further include an outer package. This outer package may be used to package the above - mentioned electrode assembly and 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 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 to 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 electrolytic solution 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 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 electrolytic solution. 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 electrolytic solution is injected, and through processes such as vacuum packaging, standing, formation, 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. 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 in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. 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 FIG. 4 and FIG. 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 manner.

[0197] Power consumption device The fourth aspect of the embodiments of the present application provides a power consumption device, which includes at least one of the secondary battery, battery module, or secondary battery pack of the third aspect of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit of the power consumption device. The power consumption device may be a mobile device (such as a mobile phone, laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, electric bicycle, electric scooter, electric golf cart, electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc., but is not limited thereto.

[0198] The power consumption device may select a secondary battery, battery module, or battery pack according to its usage requirements.

[0199] FIG. 6 is a schematic diagram of a power consumption device as an example. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements for high output and high energy density of this power consumption device, a battery pack or battery module may be adopted.

[0200] As another example of the power consumption device, it may be a mobile phone, a tablet computer, a laptop computer, etc. This power consumption device generally requires thinning and can adopt a secondary battery as a power source.

[0201] The following embodiments describe the content disclosed in this application in more detail. These embodiments are merely for discussion and explanation purposes, and it is 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 following embodiments are based on mass, and all reagents used in the embodiments can be obtained commercially or synthesized according to ordinary methods and can be used directly without further treatment, and all instruments used in the embodiments can be obtained commercially.

[0202] Example 1 Manufacture of silicone particles Production of prepolymer: 300 g of deionized water and 1.5 g of sodium dodecyl sulfate were added to a 5 L three-necked flask, stirred at a rotation speed of 1500 r / min for 30 min to emulsify, and a uniform and stable emulsion was obtained. 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 sequence, and stirring was continued at a rotation speed of 1500 r / min for 30 min to obtain a uniform prepolymer.

[0203] Manufacture of silicone particles: Add 0.6 g of sodium dodecyl sulfate and 200 g of deionized water to a dried three-necked flask, stir at high speed for 30 min for emulsification to obtain a uniform and stable emulsion. Then, use a peristaltic pump to slowly dropwise add the prepolymer and initiator solution (dissolve 0.6 g of potassium persulfate in 10 g of deionized water to form a solution) prepared in the previous step respectively. After the dropping is completed, raise the temperature to 90 °C and keep warm for 0.5 h for reaction, cool to 40 °C, adjust the pH to 7 - 8 with ammonia water, then filter, discharge, and obtain silicone particles with a number average molecular weight of 25473 through a drying process, and record as O1. And the water content of O1 is 1000 μg / g, the volume distribution particle size Dv90 is 1.5 μm, the volume distribution particle size Dv50 is 1.2 μm, the volume distribution particle size Dv10 is 0.4 μm, and the specific surface area is 20 m 2 / g.

[0204] Manufacture of separator Provision of PE substrate: It had a thickness of 6 μm and a porosity of 30%.

[0205] Manufacture of coating slurry: Mix silicone particles O1 and polyvinyl alcohol in water at a ratio (mass ratio 8:2) to prepare a coating slurry.

[0206] Coating: Coat the prepared coating slurry on both sides of the PE substrate with a coater, and obtain a separator through drying and slitting processes.

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

[0208] Manufacture of negative electrode plate Artificial graphite as the negative electrode active material, carbon black (Super P) as the conductive agent, styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) as the binder were uniformly mixed in an appropriate amount of solvent deionized water 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 the processes of drying, cold pressing, slitting, and cutting, a negative electrode plate was obtained.

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

[0210] Manufacture of battery cell 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. 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] Production of prepolymer: 1400 g of deionized water and 7 g of sodium dodecyl sulfate were added to a 5 L three-necked flask, stirred at a rotation speed of 1500 r / min for 30 min for emulsification to obtain a uniform 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 sequence, and stirring was continued at a rotation speed of 1500 r / min for 30 min to obtain a uniform prepolymer.

[0214] Production of silicone particles: 3 g of sodium dodecyl sulfate and 1000 g of deionized water were added to a dried three-necked flask, stirred at high speed for 30 min for emulsification to obtain a uniform and stable emulsion. Next, the prepolymer and initiator solution (3 g of potassium persulfate was dissolved in 30 g of deionized water to form a solution) produced in the previous step were slowly dropped using a peristaltic pump. After the dropping was completed, the temperature was raised to 90 °C and kept warm for 0.5 h for reaction, cooled to 40 °C, the pH was adjusted to 7 - 8 with ammonia water, then filtered, discharged, and passed through a drying process to obtain silicone particles with a number average molecular weight of 39529, and recorded as O2, and the water content of O2 was 1500 μg / g, the volume distribution particle size Dv90 was 1.8 μm, the volume distribution particle size Dv50 was 1.2 μm, the volume distribution particle size Dv10 was 0.6 μm, and the specific surface area was 10 m 2 / g.

[0215] Comparative Example 1 The battery cell was manufactured in a method similar to Example 1, and the difference lies in the parameters related to the coating of the separator, such as the material of the particles and M / (H·ρ 有機 ) and the details of the parameters are as shown in Table 1.

[0216] Test section (1) Thermal shrinkage rate test of the separator Sample production: Punch out the above-produced separator into samples with a width of 50 mm and a length of 100 mm using a press, place 5 parallel samples on A4 paper and fix them, and then place the A4 paper with the samples on cardboard with a thickness of 1 mm to 5 mm.

[0217] Sample test: Put the A4 paper placed on the cardboard into a forced-air oven, set the temperature of the forced-air oven to 150 °C, start timing after the temperature reaches the set temperature and stabilizes for 30 minutes, and after 1 hour has passed, measure the length and width of the separator, and denote 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%, and take the average value of 5 parallel samples as the test result.

[0219] (2) Battery capacity retention rate test At 25 °C, charge to 4.3 V at a constant current of 1 / 3C, then charge at a constant voltage of 4.3 V until the current reaches 0.05C, let it stand for 5 min, then discharge to 2.8 V at 1 / 3C, and denote the obtained capacity as the initial capacity C0. The discharge capacity C of the battery after 1000 cycles 1000 is recorded simultaneously, and the battery capacity retention rate P 1000 = C 1000 / C0 * 100%.

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

[0221]

Table 1

[0222] Based on Table 1, when comparing the test results of Examples 1 - 12 and Comparative Example 1, it can be seen that the coating contains a particulate organic material, and the separator is M / (H×ρ 有機)It satisfies ≥0.4. On the one hand, the organic materials in the coating can be reasonably deposited. When the separator receives heat, the mutual pressing between the organic materials can provide a force acting in the opposite direction to the shrinking direction of the separator, reduce the shrinking degree of the separator, and further reduce the short-circuit risk between the positive electrode and the negative electrode in the battery using this separator, enabling the battery to have good thermal safety performance. On the other hand, while reasonably depositing the organic materials 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 within 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.

[0223] It should be noted that this application is not limited to the above embodiments. The above embodiments are illustrative, and embodiments having substantially the same configuration in terms of technical idea and the same operational effects within the scope of the technical solution of this application are all included within the technical scope of this application. In addition, within the scope not departing from the spirit of this application, various modifications conceivable by those skilled in the art to the embodiments, and other forms constituted by combining some components in the embodiments are also included within the scope of this application.

Description of Reference Numerals

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

Claims

1. A separator comprising: a base material; and a coating provided on at least one side of the base material, the coating containing a particulate organic material; Here, let the weight per unit area of one side of the coating be denoted as M, the thickness of one side of the coating be denoted as H, and the true density of the organic material be ρ 有機 be denoted as such. 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 . This is the separator.

2. 0.5 ≤ M / (H × ρ 有機 )≤ 0.8, the separator according to claim 1.

3. ρ 有機 is ≦ 2.5, and optionally, 0.8 ≦ ρ 有機 ≦ 2.0, the separator according to claim 1 or 2.

4. The separator according to any one of claims 1 to 3, wherein M≥0.5, and optionally, 0.7≤M≤3.

0.

5. The separator according to any one of claims 1 to 4, wherein H≤3.0, and optionally, 0.5≤H≤2.

0.

6. The separator according to any one of claims 1 to 5, wherein M / H≥0.3, and optionally, 0.5≤M / H≤1.

0.

7. The separator according to any one of claims 1 to 6, wherein the mass ratio of the organic material in the coating is 60% or more, and optionally 75% to 95%.

8. The organic material includes one or more of silicone particles, melamine formaldehyde resin particles, phenol resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramide particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, and polyaryl ether ketone particles; Optionally, the separator according to any one of claims 1 to 7, wherein the organic material includes silicone particles.

9. The organic material includes silicone particles, and the silicone particles include a first polymer, the first polymer including a first structural unit, a second structural unit, and a third structural unit; The first structural unit has a structure represented by formula (I); 【Chemical 1】 In formula (I), R １ includes one or more of a hydrogen atom, or a substituted or unsubstituted C1-C5 alkyl group, and optionally, R １ includes one or more of a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl group. 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, and optionally, R ２ contains one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group The second structural unit is as shown in formula (II); 【Chemical 2】 In formula (II), R ３ includes one or more of a hydrogen atom, or a substituted or unsubstituted C1-C5 alkyl group, and optionally, R ３ includes one or more of a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl group. The third structural unit is as shown in formula (III); [Chemical 3] In formula (III), R ４ to R １１ each independently represents a substituted or unsubstituted C1-C10 alkyl group, or contains one or more of the structural units represented by formula (III-1), and at least one of R ４ to R １１ is a structural unit represented by formula (III-1). 【Chemical Formula 4】 In formula (III-1), R １２ comprises one or more of a hydrogen atom, or a substituted or unsubstituted C1-C5 alkyl group, and optionally, R １２ comprises one or more of a hydrogen atom, or a substituted or unsubstituted C1-C3 alkyl group. R １３ comprises a substituted or unsubstituted C1-C10 alkyl group, and optionally, R １３ comprises a substituted or unsubstituted C3-C10 alkyl group, the separator according to any one of claims 1 to 8.

10. Based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is denoted as a%, and 70≤a≤90, 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%, and 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%, where 0 < c ≦ 15, and optionally, 4 ≦ c ≦ 10. The separator according to claim 9.

11. 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%, and the molar content of the third structural unit is denoted as c%. 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). The separator according to claim 9 or 10.

12. The organic material contains silicone particles, and the silicone particles contain a second polymer. The second polymer contains a structural unit represented by formula (a). 【Chemical Formula 5】 In formula (a), R １４ and R １５ are each independently selected from a substituted or unsubstituted C1-C10 alkyl group, a hydroxy group or an amino group, and optionally, R １４ and R １５ are each independently selected from a substituted or unsubstituted C1-C6 alkyl group, a hydroxy group or an amino group, Optionally, the second polymer contains one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, and polymethylaminosiloxane. The separator according to any one of claims 1 to 11.

13. The number average molecular weight of the silicone particles is from 25,000 to 60,000, and optionally from 30,000 to 50,000. The separator according to any one of claims 9 to 12.

14. Based on the mass of the silicone particles, the water content of the silicone particles is 3000 μg / g or less, and optionally from 700 μg / g to 2500 μg / g. The separator according to any one of claims 9 to 13.

15. The volume distribution particle size Dv90 of the silicone particles satisfies Dv90 ≦ 4.0 μm, and optionally, 0.5 μm ≦ Dv90 ≦ 3.0 μm. Optionally, the volume distribution particle size Dv50 of the silicone particles satisfies 1.0 μm ≦ Dv50 ≦ 2.5 μm. Optionally, the particle size distribution of the silicone particles satisfies 0.5 ≦ (D Ｖ 90 - D Ｖ 10) / D Ｖ 50 ≦ 1.5, and the separator according to any one of claims 9 to 14.

16. The specific surface area of the silicone particles is 35 m ２ / g or less, and is selectively 5 m ２ / g to 30 m ２ / g. The separator according to any one of claims 9 to 15.

17. The thickness of the base material is 12 μm or less, and optionally from 3 μm to 8 μm, and / or The base material has a porous structure, and the porosity of the base material is 20% or more, and optionally from 25% to 45%. The separator according to any one of claims 1 to 16.

18. The separator is The separator has a longitudinal thermal shrinkage rate of 3% or less at 150°C for 1 hour, and a transverse thermal shrinkage rate of 2% or less at 150°C for 1 hour, and the air permeability of the separator is 200 s / 100 mL or less, and selectively 150 s / 100 mL to 200 s / 100 mL. (4) The longitudinal tensile strength of the separator is 2700 kgf / cm or more. ２ and the feature that... (5) The lateral tensile strength of the separator is 2500 kgf / cm ２ The separator according to any one of claims 1 to 17, satisfying at least one of the above characteristics.

19. A step of providing a substrate, a step of mixing particulate organic material with a solvent to prepare a coating slurry, a step 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, let the weight per unit area of one side of the coating be denoted as M, the thickness of one side of the coating be denoted as H, and the true density of the organic material be ρ 有機 It is denoted as such, and 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 . The separator according to any one of claims 1 to 18

20. A secondary battery, comprising the separator according to any one of claims 1 to 18 or the separator obtained by the manufacturing method according to claim 19.

21. A power consumption device, comprising the secondary battery according to claim 20.

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