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

Abstract

The present application provides a separator, a method for manufacturing the same, and related secondary batteries and power consumption devices. The separator includes a porous substrate and a coating layer provided on at least one surface of the porous substrate, the coating layer including a three-dimensional framework and organosilicone particles, and at least a portion of the organosilicone particles are packed into the three-dimensional framework. Figure 1

Description

[Technical Field]

[0001] The present application relates to separators, methods for manufacturing the same, and related secondary batteries and power consuming devices. [Background technology]

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the increasing application and popularity of secondary batteries, the requirements for their reliability are becoming increasingly stringent. How to improve the reliability of secondary batteries without affecting other performances of the secondary batteries remains a challenge for those skilled in the art. Summary of the Invention

[0003] The present application provides a separator that can provide a secondary battery with a combination of high energy density, high thermal stability, long cycle life, and good dynamic performance, a method for manufacturing the same, and related secondary batteries and power consuming devices.

[0004] A first aspect of the present application provides a separator comprising a porous substrate and a coating layer provided on at least one surface of the porous substrate, the coating layer comprising a three-dimensional skeletal structure and organosilicone particles, at least a portion of the organosilicone particles being filled in the three-dimensional skeletal structure.

[0005] By providing a coating layer consisting of a three-dimensional skeletal structure and organic silicone particles on the surface of the porous substrate of the separator and filling at least a portion of the organic silicone particles into the three-dimensional skeletal structure, the separator can be endowed with high heat resistance, high adhesiveness, and high ionic conductivity, and furthermore, the secondary battery can be endowed with high energy density, high thermal stability, long cycle life, and good dynamic performance.

[0006] In any embodiment of the present application, taking the volume distribution particle size Dv50 of the organic silicone particles as d1 with the unit of nm, the average diameter of the material constituting the three-dimensional skeleton structure as D1 with the unit of nm, and the average length of the material constituting the three-dimensional skeleton structure as L1 with the unit of nm, then 0 < D1 / (d1 / √6) ≦ 1 and 0 < d1 / (L1 / √2) ≦ 1.

[0007] By adjusting D1 / (d1 / √6) and d1 / (L1 / √2) within the above ranges, it is advantageous for the organic silicone particles and the three-dimensional skeleton structure to be overlapped and connected to form an integrated effect, enabling the coating layer to have a stable spatial network structure. Thereby, the heat resistance, adhesion, and ion conductivity of the separator can be further improved, and the thermal stability, cycle performance, and dynamic performance of the secondary battery can be further improved.

[0008] In any embodiment of the present application, 0.04 ≦ D1 / (d1 / √6) ≦ 0.85, and optionally 0.05 ≦ D1 / (d1 / √6) ≦ 0.65.

[0009] In any embodiment of the present application, 0.04 ≦ d1 / (L1 / √2) ≦ 0.9, and optionally 0.08 ≦ d​​​​​​​​​​​In any embodiment of the present application, the material constituting the three-dimensional framework has an average diameter D1, which is 50 nm or less, and optionally 10 to 42 nm. When the average diameter of the material constituting the three-dimensional framework is within the above range, the ionic conductivity and voltage breakdown characteristics of the separator can be further improved, and the organic silicone particles can be overlapped and connected to form an integrated effect, thereby further improving the heat resistance of the separator.

[0013] In any embodiment of the present application, the average length of the material constituting the three-dimensional framework is defined as L1, and L1 is 100 to 3500 nm, and optionally 400 to 3000 nm. When the average length of the material constituting the three-dimensional framework is within the above range, the heat resistance and ionic conductivity of the separator can be further improved.

[0014] In any embodiment of the present application, the topography of the organosilicone particles comprises spherical and / or near-spherical shapes.

[0015] In any embodiment of the present application, the volume distribution particle size Dv90 of the organosilicone particles is 3500 nm or less, and optionally 800 to 2500 nm. A small volume distribution particle size Dv90 of the organosilicone particles is advantageous for forming a uniform coating layer.

[0016] In any embodiment of the present application, the specific surface area of ​​the organosilicone particles is S, and its unit is m 2 / g, 5.0m 2 / g≦S≦12.0m 2 / g, selectively 6.0m 2 / g≦S≦10.0m 2 When the specific surface area of ​​the organosilicone particles is within this range, it is advantageous for good overlapping connection between the particles, and a void structure is more easily formed between the organosilicone particles, which is advantageous for the movement of active ions.

[0017] In any embodiment of the present application, the true density of the organosilicone particles is 1.0 to 2.0 g / cm 3and selectively 1.2 to 1.7 g / cm 3 When the true density of the organosilicone particles is within the above range, the compressed density and bulk density of the material increase, which contributes to improving the heat resistance of the separator and also contributes to reducing coating leaks.

[0018] In any embodiment of the present application, the compressed powder density of the organosilicone particles at 30,000 N is 0.3 to 1.5 g / cm 3 and optionally, 0.5 to 1.0 g / cm 3 is.

[0019] When the compressed density of the organic silicone particle powder is within the above range, the compressed density and bulk density of the material increase, which contributes to improving the heat resistance of the separator and also contributes to reducing coating omissions.

[0020] In any embodiment of the present application, the number average molecular weight of the organosilicone particles is 20,000 to 80,000, and optionally 30,000 to 50,000. When the number average molecular weight of the organosilicone particles is within the above range, it is advantageous for forming organosilicone particles with a small particle size, realizing a thin coating layer and reducing the overall thickness of the separator, which is convenient for improving the energy density of the secondary battery.

[0021] In any embodiment of the present application, the content of the organosilicone particles is 50 wt% or more, and optionally 50 to 90 wt% or more, based on the total weight of the coating layer. When the content of the organosilicone particles is within this range, the adhesiveness, stability, swelling resistance, heat resistance, etc. of the entire separator can be further improved.

[0022] In any embodiment of the present application, the content of the three-dimensional framework structure is less than 50 wt %, and optionally 8-48 wt %, based on the total weight of the coating layer.

[0023] In any embodiment of the present application, the organosilicone particles comprise a first structural unit.

[0024] The first structural unit is represented by formula (I). [ka]

[0025] In formula (I), R 20 ~R 27 each independently contains one or more of a substituted or unsubstituted C1 to C10 alkyl group and a structural unit represented by formula (I-1), and R 20 ~R 27 At least one of them contains a structural unit represented by formula (I-1).

[0026] [ka]

[0027] In formula (I-1), R 28 contains one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R 28 contains a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group, and R 29 comprises a substituted or unsubstituted C1-C10 alkyl group, and optionally R 29 includes substituted or unsubstituted C3 to C10 alkyl groups.

[0028] In any embodiment of the present application, the organosilicone particles further comprise a second structural unit and / or a third structural unit.

[0029] The second structural unit has a structure represented by formula (II). [ka]

[0030] In formula (II), R1 includes one or more of a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, and optionally, R1 includes one or more of a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group; R2 includes 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, R2 includes one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group.

[0031] The third structural unit is represented by formula (III).

Chemical formula

[0032] In formula (III), R3 includes one or more of a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, and optionally, R3 includes one or more of a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group.

[0033] In any embodiment of the present application, with respect to 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 A%, where 0 < A ≤ 20, and optionally 5 ≤ A ≤ 20. When the molar content of the first structural unit is within the above range, the heat resistance of the organosilicon particles can be improved, its occupancy ratio is relatively small, which is beneficial to the improvement of the occupancy ratios of the second structural unit and the third structural unit, and the improvement of the performance such as the adhesiveness, stability, and swelling resistance of the whole organosilicon particles.

[0034] In any embodiment of the present application, with respect to 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 B%, where 60 ≦ B < 100, and optionally 60 ≦ B ≦ 80. When the molar content of the second structural unit is within the above range, since the occupancy ratio in the organosilicon particles is relatively large, the flexibility of the organosilicon particles is improved, and the adhesiveness of the organosilicon particles is significantly improved. When the organosilicon particles are applied to the separator, the bonding force between the organosilicon particles and the base material of the separator can be increased.

[0035] In any embodiment of the present application, with respect to 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 C%, where 0 < C ≦ 20, and optionally 5 ≦ C ≦ 20. When the molar content of the third structural unit is within the above range, the stability of the organosilicon particles can be significantly improved.

[0036] In any embodiment of the present application, with respect to 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 A%, the molar content of the second structural unit is B%, and the molar content of the third structural unit is C%. The organosilicon particles satisfy at least one of the conditions: (1) 3 ≦ B / C ≦ 16, (2) 3 ≦ B / A ≦ 16, and (3) B:C:A is (12 - 16):(1 - 4):(1 - 4).

[0037] When the molar contents of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratios, the three types of structural units in the organosilicon particles synergistically improve the adhesiveness, stability, swelling resistance, and thermal stability of the organosilicon particles simultaneously.

[0038] In any embodiment of the present application, the organosilicon particles contain a structural unit represented by formula (a).

Chemical formula

[0039] In formula (a), R 14 and R 15 are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a hydroxy group, or an amino group, and optionally, R 14 and R 15 are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C6 alkyl group, a hydroxy group, or an amino group.

[0040] Optionally, the organosilicone particles include one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, polymethylaminosiloxane, and derivatives thereof.

[0041] In any embodiment of the present application, the material constituting the three-dimensional framework structure includes at least one of a wire, a rod, a tube, and a rod.

[0042] In any embodiment of the present application, the aspect ratio of the material constituting the three-dimensional framework is 5 to 150, and optionally 20 to 100. When the aspect ratio of the material constituting the three-dimensional framework is within the above range, the ionic conductivity and the electrolyte infiltration and retention properties of the separator can be further improved.

[0043] In any embodiment of the present application, the material constituting the three-dimensional framework structure includes at least one of an organic material and an inorganic material.

[0044] In any embodiment of the present application, the organic material comprises at least one of nanocellulose, polytetrafluoroethylene nanofibers, and polyamide nanofibers, and optionally, the nanocellulose comprises at least one of cellulose nanofibers, cellulose nanowhiskers, and bacterial nanocellulose.

[0045] In any embodiment of the present application, the inorganic material comprises at least one of halloysite nanotubes, alumina nanorods, boehmite nanorods, silica nanorods, and glass fibers.

[0046] In any embodiment of the present application, the material constituting the three-dimensional framework structure comprises nanocellulose, and the nanocellulose comprises at least one of unmodified nanocellulose and modified nanocellulose.

[0047] In any embodiment of the present application, the modified nanocellulose comprises a modifying group, the modifying group comprising at least one of an amino group, a carboxyl group, an aldehyde group, a sulfonic acid group, a boric acid group and a phosphate group, and optionally at least one of a sulfonic acid group, a boric acid group and a phosphate group.

[0048] In any embodiment of the present application, the modified nanocellulose contains hydroxyl groups and modifying groups, and the molar ratio of the modifying groups to the hydroxyl groups is 1:4 to 4:1, and optionally 2:3 to 7:3. When the molar ratio of the modifying groups to the hydroxyl groups is within the above range, the heat resistance, ionic conductivity, and electrolyte infiltration and retention properties of the separator can be further improved.

[0049] In any embodiment of the present application, the material constituting the three-dimensional skeletal structure contains a sulfonic acid group, and the content of sulfur element in the material constituting the three-dimensional skeletal structure is 0.1 wt% or more, and optionally 0.2 to 0.5 wt%, relative to the total weight of the material constituting the three-dimensional skeletal structure.

[0050] In any embodiment of the present application, the coating layer further comprises a non-particulate adhesive.

[0051] In any embodiment of the present application, the content of the non-particulate adhesive in the coating layer is 5 wt % or less, based on the total weight of the coating layer.

[0052] In any embodiment of the present application, the non-particulate adhesive comprises at least one of polyacrylonitrile, acrylic resin, acrylate resin, polyvinyl alcohol, isobutylene-maleic anhydride copolymer, polyacrylamide, sodium carboxymethylcellulose, carboxymethylchitosan, sodium alginate, and derivatives thereof.

[0053] In any embodiment of the present application, the thickness of the porous substrate is 6 μm or less, and optionally 3-5 μm.

[0054] In any embodiment of the present application, the thickness of the coating layer is less than 4 μm, and optionally 0.4-3 μm.

[0055] In any embodiment of the present application, the separator has a longitudinal heat shrinkage rate of 4.5% or less at 150°C for 1 hour, and optionally 0.8% to 3%.

[0056] In any embodiment of the present application, the separator has a thermal shrinkage rate of 4.5% or less in the transverse direction at 150° C. for 1 hour, and optionally 1-3%.

[0057] In any embodiment of the present application, the separator has a longitudinal tensile strength of 1600 kg / cm 2 or more, and selectively 1800~4500kg / cm 2 is.

[0058] In any embodiment of the present application, the separator has a tensile strength in the transverse direction of 1600 kg / cm 2 or more, and selectively 1800~4500kg / cm 2 is.

[0059] In any embodiment of the present application, the wet length of the separator is 20 mm or more, optionally 30 to 80 mm.

[0060] In any embodiment of the present application, the wetting speed of the separator is 2 mm / s or more, and is 3 to 10 mm / s.

[0061] In any embodiment of the present application, the separator has an air permeability of 350 s / 100 mL or less, and optionally 100 to 270 s / 100 mL.

[0062] In any embodiment of the present application, the ionic conductivity of the separator is 0.5 mS / cm or more, and optionally 0.55 to 0.98 mS / cm.

[0063] A second aspect of the present application provides a method for producing the separator of the first aspect of the present application, the method comprising the steps of: providing a porous substrate; kneading organosilicone particles and an adhesive, and then adding a material for constituting a three-dimensional skeletal structure and a solvent and uniformly mixing them to prepare a coating layer slurry; and applying the coating layer slurry to at least one surface of the porous substrate and drying it to obtain a separator, wherein the separator comprises a porous substrate and a coating layer provided on at least one surface of the porous substrate, the coating layer comprising a three-dimensional skeletal structure and organosilicone particles, and at least a portion of the organosilicone particles are filled in the three-dimensional skeletal structure.

[0064] A third aspect of the present application provides a secondary battery including the separator of the first aspect of the present application or a separator produced by the method of the second aspect of the present application.

[0065] A fourth aspect of the present application provides a power consuming device including the secondary battery of the third aspect of the present application.

[0066] The power consumption device of the present application includes the secondary battery of the present application, and therefore has at least the same advantages as the secondary battery. [Brief explanation of the drawings]

[0067] In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings required in the embodiments of the present application will be briefly described below. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] 1 is a schematic diagram of an embodiment of a secondary battery of the present application. [Figure 2] FIG. 2 is an exploded schematic view of the embodiment of the secondary battery of FIG. [Figure 3] 1 is a schematic diagram of an embodiment of a battery module of the present application. [Figure 4] 1 is a schematic diagram of an embodiment of a battery pack of the present application. [Figure 5] 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4. [Figure 6] 1 is a schematic diagram of one embodiment of a power consuming device that includes a secondary battery of the present application as a power source. [Explanation of symbols]

[0068] 1 battery pack 2 Upper Box 3 Lower Box 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cover plate DETAILED DESCRIPTION OF THE INVENTION

[0069] Hereinafter, embodiments of the separator of the present application, its manufacturing method, and related secondary batteries and power consumption devices will be described in detail with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0070] The "ranges" disclosed herein are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of that particular range. Such defined ranges may be exclusive of or inclusive of the end values, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​1 and 2 and maximum range values ​​3, 4, and 5 are recited, the following ranges can be contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. Unless otherwise specified, the numerical range "a to b" is represented by the abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 and 5" are listed herein, and "0 to 5" is an abbreviation for combinations of these numbers. Also, when a parameter is an integer greater than or equal to 2, the parameter is disclosed as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0071] Unless otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0072] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0073] Unless otherwise specified, all steps herein may be performed in order or randomly, but are preferably performed in order. For example, the method may include steps (a) and (b), and the method may include steps (a) and (b) performed in order, or may include steps (b) and (a) performed in order. For example, the method may further include step (c), and step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0074] Unless otherwise specified, the terms "comprise" and "comprise" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "comprise" may mean that the composition further contains other components not listed, or may contain only the listed components.

[0075] Unless otherwise specified, in this application, the term "or" is an inclusive term. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" satisfies any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and both A and B are true (or exist).

[0076] Unless otherwise specified, in this application, the terms "first," "second," "third," etc. are used to distinguish between different objects and do not describe a particular order or hierarchy.

[0077] As used herein, the terms "plurality," "plural types," and the like mean two or more than two.

[0078] Unless otherwise specified, terms used in this application have the known meanings commonly understood by those skilled in the art.

[0079] Unless otherwise specified, the values ​​of the parameters mentioned herein can be measured by various test methods commonly used in the art, for example, by the test methods described in the Examples of the present application. Unless otherwise specified, the test temperature is 25°C.

[0080] The term "alkyl group" includes linear and branched alkyl groups. For example, the alkyl group may be a C1-C50 alkyl group, a C1-C40 alkyl group, a C1-C30 alkyl group, a C1-C20 alkyl group, a C1-C12 alkyl group, a C1-C10 alkyl group, a C1-C6 alkyl group, a C1-C5 alkyl group, or a C1-C3 alkyl group. In some embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and the like. Additionally, the alkyl group may be optionally substituted.

[0081] The term "cycloalkyl group" refers to a ring structure formed by three or more carbon atoms. The cyclic alkyl group may be, for example, a C3-C50 cycloalkyl group, a C3-C40 cycloalkyl group, a C3-C30 cycloalkyl group, a C3-C20 cycloalkyl group, a C3-C12 cycloalkyl group, a C3-C10 cycloalkyl group, a C3-C6 cycloalkyl group, or a C3-C4 cycloalkyl group. In some embodiments, the cyclic alkyl group includes a cyclopropyl group, a cycloisopropyl group, a cyclobutyl group, a cycloisobutyl group, a cyclo-t-butyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like. The cyclic alkyl group may also be optionally substituted.

[0082] The term "hydroxyalkyl group" refers to an alkyl group in which one of the hydrogen atoms has been replaced with a hydroxy group. For example, the hydroxyalkyl group can be a C1-C50 hydroxyalkyl group, a C1-C40 hydroxyalkyl group, a C1-C30 hydroxyalkyl group, a C1-C20 hydroxyalkyl group, a C1-C12 hydroxyalkyl group, a C1-C10 hydroxyalkyl group, a C1-C6 hydroxyalkyl group, a C1-C5 hydroxyalkyl group, or a C1-C3 hydroxyalkyl group. In some embodiments, the alkyl group includes a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxyisopropyl group, a hydroxybutyl group, a hydroxyisobutyl group, a hydroxytert-butyl group, a hydroxypentyl group, a hydroxyhexyl group, a hydroxyheptyl group, a hydroxyoctyl group, and the like. The alkyl group can also be optionally substituted.

[0083] The term "hydrogen" means 1H (protium, H), 2H (deuterium, D) or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (protium, H).

[0084] At various places in this specification, substituents of compounds are disclosed in groups or in ranges, and it is specifically contemplated that such descriptions also include each individual subcombination of the members of these groups and ranges. For example, the term "C1-C8 alkyl" can be expressly expected to disclose C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7 and C7-C8 alkyl groups singly. As another example, the range of integers from 5 to 40 is specifically contemplated to individually disclose 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40. The range of integers from 1 to 20 is specifically contemplated to individually disclose 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Other groups or ranges are specifically contemplated herein.

[0085] When the above groups (eg, alkyl, cycloalkyl, hydroxyalkyl, etc.) are substituted, the substituents may contain halogen atoms or heteroatoms.

[0086] The term "halogen atom" includes fluorine atom, chlorine atom and bromine atom.

[0087] The term "heteroatom" includes nitrogen atoms, sulfur atoms, phosphorus atoms, and the like.

[0088] Typically, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet and serves mainly to prevent short circuits between the positive and negative electrodes, while allowing active ions to pass freely through the separator to form a circuit.

[0089] As secondary batteries become more widely used and widespread, the demands for their performance (e.g., reliability) are becoming increasingly high. Separators are an important component of secondary batteries, and improving their performance can improve their reliability. Currently, separators used in commercial secondary batteries are typically porous polyolefin membranes, which have poor heat resistance and a significant thermal shrinkage effect due to heat. This can lead to direct contact between the positive and negative electrodes inside the battery, causing internal short circuits and increasing safety risks for secondary batteries.

[0090] To solve the above problems, conventionally, a heat-resistant inorganic ceramic layer has been applied to a polyolefin porous film. However, the inorganic ceramic layer's effect of improving the heat resistance of the separator is limited, and the inorganic ceramic layer has poor adhesion, prone to powder shedding, and poor adhesion between the inorganic ceramic layer and the positive and negative electrode sheets. Coating a polyolefin porous film with a coating layer containing a polymer can improve the adhesion of the coating layer, but the polymer coating layer has the problem of high-temperature shrinkage and poor ionic conductivity.

[0091] As described above, it is difficult for the separators of the related art to have high adhesiveness, high heat resistance, and high ionic conductivity at the same time.

[0092] In the course of their research, the inventors of the present application surprisingly discovered that by providing a coating layer containing a three-dimensional skeletal structure and organosilicone particles on the surface of a separator porous substrate, and by filling at least a portion of the organosilicone particles into the three-dimensional skeletal structure, it is possible to impart to the separator high heat resistance, high adhesion, and high ionic conductivity, and further to impart to the secondary battery high energy density, high thermal stability, long cycle life, and good dynamic performance.

[0093] A first aspect of an embodiment of the present application provides a separator including a porous substrate and a coating layer provided on at least one surface of the porous substrate, wherein the coating layer includes a three-dimensional skeletal structure and organosilicone particles, and at least a portion of the organosilicone particles are filled in the three-dimensional skeletal structure.

[0094] The term "three-dimensional skeletal structure" refers to a structure having a three-dimensional spatial shape and a certain amount of voids, and the materials that make up the three-dimensional skeletal structure are overlapped and connected to each other.

[0095] The term "organosilicone particles" generally refers to particulate materials made of siloxane compounds containing --Si--O-- structural units.

[0096] The three-dimensional skeletal structure has the advantage of a large specific surface area, has good affinity with organic silicone particles, and can improve the adhesive effect provided that a small amount of adhesive is used, thereby reducing the self-discharge of the secondary battery and improving the cycle performance and dynamic performance of the secondary battery.

[0097] By filling at least a portion of the organosilicone particles into the three-dimensional skeletal structure, the heat resistance of the separator is improved, the degree of thermal shrinkage of the separator is reduced, the risk of short-circuiting between the positive and negative electrodes is reduced, the secondary battery has high thermal stability, and high adhesive strength can be maintained between the coating layer and the porous substrate and between the coating layer and the electrode sheet (e.g., the positive electrode sheet, the negative electrode sheet), thereby reducing the probability of the organosilicone particles falling off during the long-term charge / discharge process of the secondary battery and improving the interface between the separator and the electrode sheet. Furthermore, by filling at least a portion of the organosilicone particles into the three-dimensional skeletal structure, the separator has high porosity and high ionic conductivity.

[0098] At the same time, since the density of the organic silicone particles is smaller than that of conventional inorganic ceramic particles, it is possible to reduce the weight of the secondary battery and improve the weight energy density of the secondary battery.

[0099] Therefore, the separator according to the embodiment of the present application can have high heat resistance, high adhesion, and high ionic conductivity, and further, the secondary battery using the separator can have high energy density, high thermal stability, long cycle life, and good dynamic performance.

[0100] In some embodiments, at least a portion of the organosilicone particles may be filled into the three-dimensional skeletal structure, and another portion of the organosilicone particles may be located on the surface of the three-dimensional skeletal structure and / or at the interface between the three-dimensional skeletal structure and the porous substrate. At the interface between the three-dimensional skeletal structure and the porous substrate, at least a portion of the organosilicone particles may be embedded in the porous substrate. For example, during the winding process of the electrode assembly, a minority portion of the organosilicone particles at the interface may be embedded in the matrix and / or pores of the porous substrate due to the action of external pressure.

[0101] In some embodiments, when the volume-average particle size Dv50 of the organic silicone particles is d1 with the unit of nm, the average diameter of the material constituting the three-dimensional skeleton structure is D1 with the unit of nm, and the average length of the material constituting the three-dimensional skeleton structure is L1 with the unit of nm, 0 < D1 / (d1 / √6) ≦ 1 and 0 < d1 / (L1 / √2) ≦ 1.

[0102] By adjusting D1 / (d1 / √6) and d1 / (L1 / √2) within the above ranges, it is advantageous for the organic silicone particles and the three-dimensional skeleton structure to be superposed and connected to form an integration effect, enabling the coating layer to have a stable spatial network structure. Thereby, the heat resistance, adhesion, and ionic conductivity of the separator can be further improved, and the thermal stability, cycle performance, and dynamic performance of the secondary battery can be further improved.

[0103] Optionally, 0.04 ≦ D1 / (d1 / √6) ≦ 0.85, 0.045 ≦ D1 / (d1 / √6) ≦ 0.7, 0.05 ≦ D1 / (d1 / √6) ≦ 0.65, 0.055 ≦ D1 / (d1 / √6) ≦ 0.5, 0.055 ≦ D1 / (d1 / √6) ≦ 0.5, 0.058 ≦ D1 / (d1 / √6) ≦ 0.4. Thereby, the heat resistance, adhesion, and ionic conductivity of the separator can be better improved, and the thermal stability, cycle performance, and dynamic performance of the secondary battery can be better improved.

[0104] Optionally, 0.04 ≦ d1 / (L1 / √2) ≦ 0.9, 0.08 ≦ d1 / (L1 / √2) ≦ 0.8, 0.10 ≦ d1 / (L1 / √2) ≦ 0.8, 0.12 ≦ d1 / (L1 / √2) ≦ 0.79, 0.14 ≦ d1 / (L1 / √2) ≦ 0.78, 0.16 ≦ d1 / (L1 / √2) ≦ 0.78. Thereby, the heat resistance, adhesion, and ionic conductivity of the separator can be better improved, and the thermal stability, cycle performance, and dynamic performance of the secondary battery can be better improved.

[0105] In some embodiments, 0.04≦D1 / (d1 / √6)≦0.85 and 0.04≦d1 / (L1 / √2)≦0.9, optionally 0.05≦D1 / (d1 / √6)≦0.65 and 0.08≦d1 / (L1 / √2)≦0.8, and more preferably 0.058≦D1 / (d1 / √6)≦0.4 and 0.16≦d1 / (L1 / √2)≦0.78, thereby improving the heat resistance, adhesion, and ionic conductivity of the separator and thereby improving the thermal stability, cycle performance, and dynamic performance of the secondary battery.

[0106] In some embodiments, the organosilicone particles have a volume distribution particle size Dv50 of d1, which may be 2000 nm or less, and may be 275 to 1500 nm, 350 to 1500 nm, or 400 to 1200 nm. When the organosilicone particles have a small volume distribution particle size Dv50, they are packed into a three-dimensional skeletal structure, forming a nesting effect, which is advantageous for improving the heat resistance, adhesiveness, and ionic conductivity of the separator.

[0107] In some embodiments, the volume distribution particle size Dv90 of the organosilicone particles can be 3500 nm or less, optionally 800 to 2500. A small volume distribution particle size Dv90 of the organosilicone particles is advantageous for forming a uniform coating layer.

[0108] The volume distribution particle diameters Dv50 and Dv90 of a material have the meanings known in the art and indicate the particle diameters corresponding to the cumulative volume distribution percentages of the material reaching 50% and 90%, respectively, and can be measured using instruments and methods known in the art, such as GB / T 19077-2016, which can be tested using a laser particle size analyzer (e.g., Master Size 3000).

[0109] In some embodiments, the topography of the organosilicone particles may include spherical and / or near-spherical shapes. The spherical and / or near-spherical particle shape promotes good interparticle connection and the presence of voids between particles, which is advantageous for building a stable spatial network structure, thereby improving the ion transport properties and extrusion resistance of the separator. Furthermore, the large voids between the spherical and / or near-spherical particles reduce the influence of the gas permeability of the coating layer on the porous substrate, further improving the gas permeability and ionic conductivity of the entire separator and improving the dynamic performance of the secondary battery. Furthermore, the relatively large porosity between the spherical and / or near-spherical particles is advantageous for improving the separator's electrolyte wettability and the separator's liquid holdup and retention rate, further improving the dynamic performance of the secondary battery. Furthermore, the large porosity contributes to weight reduction, which is advantageous for improving the energy density per unit weight of the secondary battery. Furthermore, the amount of organosilicone particles used in the coating layer can be reduced, which is advantageous for reducing the cost of the secondary battery.

[0110] The topography of the organosilicone particles can be observed using a scanning electron microscope (SEM), for example, a JSM-5610LV scanning electron microscope manufactured by FEI Corporation, USA, is used to observe the topographic structure after vacuum-depositing gold on the sample.

[0111] In some embodiments, the specific surface area of ​​the organosilicone particles is S, and its unit is m 2 / g, 5.0m 2 / g≦S≦12.0m 2 / g, selectively 6.0m 2 / g≦S≦10.0m 2 When the specific surface area of ​​the organosilicone particles is within this range, it is advantageous for good overlapping connection between the particles, and it is easier to form a void structure between the organosilicone particles, which is advantageous for the movement of active ions.

[0112] The specific surface area of ​​organosilicone particles has a meaning known in the art and can be measured using known instruments and methods in the art.For example, it can be tested according to the nitrogen gas adsorption specific surface area analysis test method in accordance with GB / T 19587-2017, and calculated by the Brunauer Emmett Teller (BET) method.Optionally, the nitrogen gas adsorption specific surface area analysis test can be performed using a Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, USA.

[0113] In some embodiments, the organosilicone particles have a true density of 1.0 to 2.0 g / cm 3 , selectively 1.2~1.7g / cm 3 It can be.

[0114] When the true density of the organosilicone particles is within the above range, the compressed density and bulk density of the material increase, which contributes to improving the heat resistance of the separator and also contributes to reducing coating omissions.

[0115] The true density of organosilicone particles has a known meaning in the art, and can be measured by known instruments and methods in the art.For example, referring to GB / T 24586-2009, inert gas (such as helium gas or nitrogen gas) can be used as a medium, and the true volume Vt of test sample can be measured by gas displacement method using a true density tester.The true density of organosilicone particles = mass of test sample / true volume Vt of test sample.

[0116] In some embodiments, the organosilicone particles have a powder compression density of 0.3 to 1.5 g / cm at 30,000 N. 3 , selectively 0.5~1.0g / cm 3 It can be.

[0117] When the compressed density of the organic silicone particle powder is within the above range, the compressed density and bulk density of the material increase, which contributes to improving the heat resistance of the separator and also contributes to reducing coating omissions.

[0118] The pressed density of the powder of organosilicone particles has a meaning known in the art and can be measured using equipment and methods known in the art. For example, it can be measured using an electronic pressure tester (e.g., UTM7305 type) with reference to GB / T 24533-2009. An exemplary test method is to weigh 1 g of material and measure the density of the powder with a base area of ​​1.327 cm. 2 The material was placed in a mold, pressurized to 30,000 N, and held for 30 seconds, after which the pressure was released and held for 10 seconds, and then recorded, and the compressed density of the powder of the material at 30,000 N was calculated.

[0119] In some embodiments, the number average molecular weight of the organosilicone particles may be 20,000 to 80,000, optionally 25,000 to 70,000, or 30,000 to 50,000. Illustratively, the number average molecular weight of the organosilicone particles may be 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, or a range consisting of any two of the foregoing values. When the number average molecular weight of the organosilicone particles is within the above range, it is advantageous to form organosilicone particles with a small particle size, which enables a thin coating layer to be formed and the overall thickness of the separator to be reduced, which is convenient for improving the energy density of the secondary battery. In addition, the particle size of the organosilicone particles formed from the organosilicone particles is not too small, which reduces the risk of the organosilicone particles blocking the porous substrate, which makes it easier to improve the performance of the separator as a whole, such as the air permeability and ionic conductivity.

[0120] The number average molecular weight of organic silicone particles can be measured by gel permeation chromatography (GPC).Specifically, the test is carried out using a GPC1515 instrument manufactured by Waters, USA, in which the sample is dissolved in tetrahydrofuran, the dissolution time is 12 hours or more, the sample concentration is 4 mg / ml, the sample is filtered, the test temperature is 25°C, and the test flow rate is 1 ml / min.

[0121] In some embodiments, the organosilicone particles include a first structural unit, and the first structural unit can have a structure represented by formula (I). [ka]

[0122] In formula (I), R 20 ~R 27 each independently contains one or more of a substituted or unsubstituted C1 to C10 alkyl group and a structural unit represented by formula (I-1), and R 20 ~R 27 At least one of them contains a structural unit represented by formula (I-1). [ka]

[0123] In formula (I-1), R 28 contains one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R 28 contains a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group, and R 29 comprises a substituted or unsubstituted C1-C10 alkyl group, and optionally R 29 includes substituted or unsubstituted C3 to C10 alkyl groups.

[0124] The first structural unit is formed by breaking the carbon-carbon double bond of the substituted or unsubstituted acryloyloxy group in the substituted or unsubstituted acryloyloxyalkyl polysilsesquioxane during polymerization. Polysilsesquioxane is a material having an organic-inorganic hybrid core-shell structure, in which the inorganic framework inside is the core, i.e., a skeletal structure consisting of Si-O-Si or Si-O bonds, and the shell is composed of organic substituents (e.g., C1-C10 alkyl groups), with the organic substituents being enclosed outside the skeletal structure and connected to the Si element of the skeletal structure. The polysilsesquioxane core structure can impart advantages in heat resistance and mechanical properties to the organic silicone particles, and its low shrinkage can maintain the stability of the organic silicone particles during the long-term cycle charge / discharge process of the secondary battery, effectively insulating the positive electrode sheet and the negative electrode sheet, thereby improving the reliability of the secondary battery. Furthermore, because polysilsesquioxane has a small particle size, a large specific surface area, and physical dimensions similar to many polymer segments, the atoms on the polysilsesquioxane surface have high reactivity, which gives the organic silicone particles excellent heat resistance, flame retardancy, antioxidant properties, and other properties.

[0125] In some embodiments, the organosilicone particles may include, in addition to the first structural unit, a second structural unit and / or a third structural unit, in which hydrogen atoms bonded to carbon atoms may be omitted and not represented by chemical bonds.

[0126] The second structural unit can have a structure represented by formula (II). [ka]

[0127] In formula (II), R1 comprises one or more of a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, and optionally R1 comprises one or more of a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group. R2 comprises one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, or a substituted or unsubstituted C1-C20 hydroxyalkyl group, and optionally R2 comprises one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, or a C1-C12 hydroxyalkyl group.

[0128] The third structural unit can have a structure represented by formula (III). [ka]

[0129] In formula (III), R3 comprises one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R3 comprises one or more of a hydrogen atom, a substituted or unsubstituted C1 to C3 alkyl group.

[0130] The second structural unit can be formed by breaking the carbon-carbon double bond in the acrylate ester monomer during the polymerization process. The flexible monomer segment in the molecular segment can adjust the glass transition temperature of the organosilicone particles, improve the toughness and peel strength of the organosilicone particles, and contribute to the excellent adhesive effect.

[0131] The third structural unit can be formed by breaking the carbon-carbon double bond in the acrylonitrile-based monomer during the polymerization process. The third structural unit exhibits excellent swelling resistance and high adhesiveness, and can contribute to improving the ionic conductivity of the secondary battery. When the organosilicone particles come into contact with the electrolyte, the organosilicone particles are less likely to swell, resulting in excellent swelling resistance.

[0132] The above analysis is carried out based on each structural unit, but the synergistic effect between each structural unit cannot be ignored. Specifically, the first structural unit and the second structural unit cooperate to exert a synergistic effect, so that the adhesion performance and heat resistance of the organosilicon particles can be improved. In addition, the second structural unit and the third structural unit cooperate to exert a synergistic effect, so that the stability, swelling resistance, etc. of the organosilicon particles can be improved.

[0133] In some embodiments, the organosilicon particles simultaneously contain the first structural unit, the second structural unit, and the third structural unit.

[0134] In some embodiments, with respect to 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 A%, and 0 < A ≤ 20. When the molar content of the first structural unit is within the above range, the heat resistance of the organosilicon particles can be improved. In addition, since its occupancy ratio is relatively small, it is beneficial to improve the occupancy ratios of the second structural unit and the third structural unit, and to improve the performance such as the adhesion, stability, and swelling resistance of the entire organosilicon particles. Optionally, 5 ≤ A ≤ 20 is satisfied. Exemplarily, the molar content of the first structural unit may be 5%, 8%, 10%, 12%, 15%, 18%, 20%, or a range composed of any two of the above numerical values.

[0135] In some embodiments, with respect to 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 B%, and 60 ≤ B < 100. When the molar content of the second structural unit is within the above range, the occupancy ratio in the organosilicon particles is relatively large, and the flexibility of the organosilicon particles can be improved. Thereby, the adhesion of the organosilicon particles is significantly improved. When the organosilicon particles are applied to the separator, the binding force between the organosilicon particles and the substrate of the separator can be increased. Optionally, 60 ≤ B ≤ 80 is satisfied. Exemplarily, the molar content of the second structural unit may be 60%, 65%, 70%, 75%, 80%, or a range composed of any two of the above numerical values.

[0136] In some embodiments, with respect to 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 C%, and 0 < C ≦ 20. When the molar content of the third structural unit is within the above range, the stability of the organosilicon particles can be significantly improved. Optionally, 5 ≦ C ≦ 20. Exemplarily, the molar content of the third structural unit may be 5%, 8%, 10%, 12%, 15%, 18%, 20%, or a range consisting of any two of the above numerical values.

[0137] The organosilicon particles contain a second structural unit, and the second structural unit imparts good adhesion and flexibility to the organosilicon particles. However, when the organosilicon particles are applied to the separator, it is inevitable to contact the electrolyte, so the swelling action of the electrolyte reduces the adhesion of the organosilicon particles to some extent. However, when the organosilicon particles further contain a third structural unit, the cyano groups in the third structural unit exert a synergistic effect with the second structural unit, and the swelling resistance and adhesion of the organosilicon particles can be improved simultaneously. In particular, when the present application further satisfies 3 ≦ B / C ≦ 16, the second structural unit can more fully exert a synergistic effect with the third structural unit, and the adhesion, stability, and swelling resistance of the organosilicon particles can be improved. Exemplarily, B / C may be 3, 4, 5, 8, 10, 12, 15, 16, 18, or a range consisting of any two of the above numerical values.

[0138] The organosilicon particles contain a second structural unit, which provides good adhesion to the organosilicon particles but has relatively poor heat resistance. When the organosilicon particles are used in a separator, the temperature inside the secondary battery increases with increasing charge / discharge time, potentially causing damage to the second structural unit. The inorganic structure of the polysilsesquioxane in the first structural unit and the second structural unit exert a synergistic effect to improve the heat resistance and adhesive performance of the entire organosilicon particle. In particular, when the present application further satisfies the relationship 3≦B / A≦16, the synergistic effect between the first structural unit and the second structural unit is more fully exerted, thereby improving the adhesive performance and heat resistance of the organosilicon particles. For example, B / A may be 3, 4, 5, 8, 10, 12, 15, 16, 18, or a range consisting of any two of the above values.

[0139] In some embodiments, B:C:A may be (12-16):(1-4):(1-4). When the molar contents 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 organosilicone particles work synergistically to simultaneously improve the adhesiveness, stability, swelling resistance, and thermal stability of the organosilicone particles.

[0140] The first structural unit may include a plurality of chemical structures, and specific chemical structures of the first structural unit will be described below.

[0141] In some embodiments, R 20 ~R 27 may each independently contain a structural unit represented by formula (I-1). 28 may contain 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 29 can include 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.

[0142] In some embodiments, R 20 ~R 27 One of the R 28 may contain 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 29 can include 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.

[0143] The second structural unit may include a plurality of chemical structures, and specific chemical structures of the second structural unit will be described below.

[0144] In some embodiments, R1 can include a hydrogen atom or a methyl group.

[0145] In some embodiments, R2 can include 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.

[0146] For example, the second structural unit can include one or more of the structures represented by formula (II-1) to formula (II-8). [ka]

[0147] The third structural unit may include a plurality of chemical structures, and specific chemical structures of the third structural unit will be described below.

[0148] In some embodiments, R3 can include a hydrogen atom or a methyl group.

[0149] For example, the third structural unit may include one or more of the structures represented by formula (III-1) to formula (III4). [ka]

[0150] The type of group in the organosilicone particles can be measured by infrared spectroscopy. For example, the type of modifying group can be identified by measuring the infrared spectrum of the material and identifying the characteristic peaks contained therein. Specifically, infrared spectroscopy analysis of the material can be performed using equipment and methods known in the art. For example, an infrared spectrophotometer (e.g., an IS10 Fourier transform infrared spectrophotometer from Nicolet, USA) is used to perform the test in accordance with GB / T 6040-2019, General Rules for Infrared Spectroscopy Analysis Methods.

[0151] In some embodiments, the organosilicone particles have an infrared spectrum of 1100 nm. -1 ~1120cm -1 This indicates the presence of the Si-O-Si skeleton of silsesquioxane.

[0152] In some embodiments, the infrared spectrum of the organosilicone particles has a wavelength of 1750 cm -1 ~1735cm -1 This indicates the presence of an ester group.

[0153] In some embodiments, the infrared spectrum of the organosilicone particles is at 2260 cm -1 ~2220cm -1 This shows the presence of a cyano group.

[0154] In some embodiments, the organosilicone particles can include structural units according to formula (a). [ka]

[0155] In formula (a), R 14 and R 15 are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a hydroxy group, or an amino group, and optionally, R 14 and R 15 are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C6 alkyl group, a hydroxy group, or an amino group.

[0156] Alternatively, the organosilicone particles may include one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, polymethylaminosiloxane, and derivatives thereof, where the derivative generally refers to a polymer in which a hydrogen atom or atomic group is replaced with another atom or atomic group.

[0157] In some embodiments, the content of the organosilicone particles may be 50 wt% or more, or optionally 50 to 90 wt%, or 50 to 88 wt%, based on the total weight of the coating layer. When the content of the organosilicone particles is within this range, the adhesiveness, stability, swelling resistance, heat resistance, etc. of the entire separator can be further improved.

[0158] In some embodiments, the content of the three-dimensional framework structure may be less than 50 wt %, optionally 8 to 48 wt %, or 10 to 48 wt %, based on the total weight of the coating layer.

[0159] In some embodiments, the material constituting the three-dimensional framework may include at least one of linear, rod-shaped, tubular, and rod-shaped materials. A material with an appropriate shape is advantageous for forming a more stable spatial network structure between the three-dimensional framework and the organosilicone particles, thereby further improving the heat resistance, ionic conductivity, and electrolyte wetting and retention properties of the separator.

[0160] In some embodiments, the average diameter of the material constituting the three-dimensional framework is designated D1, and D1 is 50 nm or less, and can be optionally 4 to 45 nm, 4 to 42 nm, 10 to 42 nm, or 16 to 40 nm. When the average diameter of the material constituting the three-dimensional framework is within the above range, the ionic conductivity and voltage breakdown characteristics of the separator can be further improved, and the overlapping and connection with the organosilicon particles can also contribute to forming an integration effect, thereby further improving the heat resistance of the separator.

[0161] In some embodiments, the average length of the material constituting the three-dimensional framework is designated L1, and L1 can be 100 to 3500 nm, or optionally 400 to 3000 nm, 500 to 3000 nm, 600 to 3000 nm, or 700 to 3000 nm. When the average length of the material constituting the three-dimensional framework is within the above range, the heat resistance and ionic conductivity of the separator can be further improved.

[0162] In some embodiments, the aspect ratio of the material constituting the three-dimensional framework is 5 to 150, and can optionally be 12 to 120, 20 to 100, 30 to 95, or 40 to 90. When the aspect ratio of the material constituting the three-dimensional framework is within the above range, the ionic conductivity and the electrolyte infiltration and retention properties of the separator can be further improved.

[0163] The average length and average diameter of the material constituting the three-dimensional skeletal structure can be measured by the following method: A 3.6 mm × 3.6 mm sample is cut out from an arbitrary region of the separator, and the micro-topography structure of the coating layer in the sample is mapped using a scanning electron microscope (e.g., ZEISS Sigma 300), high vacuum mode is selected, the operating voltage is set to 3 kV, and the magnification is set to 30,000 times to obtain an SEM image. Based on the obtained SEM image, multiple (e.g., five or more) test regions are selected and length statistics are performed, with each test region measuring 0.5 μm × 0.5 μm. The average value of the average lengths obtained from each test region is then regarded as the average length of the material constituting the three-dimensional skeletal structure. Based on the obtained SEM image, multiple (e.g., five or more) test regions are selected and diameter statistics are performed using Nano Measurement particle size distribution statistical software, with each test region measuring 0.5 μm × 0.5 μm. The average value of the average diameters obtained from each test region is then regarded as the average diameter of the material constituting the three-dimensional skeletal structure.

[0164] When the material that makes up the three-dimensional skeletal structure contains nanocellulose, the diameter at both ends of the nanocellulose in the longitudinal direction is generally small and the diameter at the middle position is generally large, so the maximum diameter in the longitudinal direction of the nanocellulose can be used as the diameter of the nanocellulose. The diameters of other nanocelluloses can be processed in a similar manner, and then the average diameter of the nanocellulose can be obtained using the Nano Measurement particle size distribution statistical software according to the method described above.

[0165] In some embodiments, the material constituting the three-dimensional framework structure can include at least one of an organic material and an inorganic material.

[0166] Optionally, the organic material may include at least one of nanocellulose, polytetrafluoroethylene nanofibers, and polyamide nanofibers.

[0167] Optionally, the inorganic material may include at least one of halloysite nanotubes, alumina nanorods, boehmite nanorods, silica nanorods, and glass fibers.

[0168] The material that constitutes the three-dimensional framework is rich in hydroxyl groups and easily bonds with the organic silicone particles and porous substrate. This improves the adhesive effect while requiring a small amount of adhesive, reduces the self-discharge of the secondary battery, and improves the cycle performance and dynamic performance of the secondary battery. It also forms a stable coating layer structure, improving the heat resistance and ionic conductivity of the secondary battery.

[0169] In some embodiments, the material constituting the three-dimensional framework may comprise nanocellulose, which may optionally comprise at least one of cellulose nanofibers (Cellulose nanofibrils, CNF, also known as nanofibril cellulose or microfibril cellulose), cellulose nanowhiskers (Cellulose nanocrystals, CNC, also known as cellulose nanocrystals or nanocrystalline cellulose), and bacterial nanocellulose (Bacterial nanocellulose, BNC, also known as bacterial cellulose or microbial cellulose).

[0170] Nanocellulose is a general term for cellulose whose one-dimensional size is on the nanometer order (e.g., within 100 nm) and combines the properties of cellulose with those of nanoparticles. Nanocellulose can be a polymeric nanomaterial extracted from natural sources such as wood or cotton by one or more means, including chemical, physical, and biological methods. It offers advantages such as a wide range of origins, low cost, biodegradability, high modulus, and high specific surface area, making it an excellent alternative to traditional petroleum resources and effectively alleviating environmental pollution and the strain on petroleum resources. Nanocellulose also has excellent high-temperature resistance and minimal thermal volume change, improving the heat resistance of separators. At the same time, its relatively low density compared to conventional inorganic ceramic particles reduces the weight of secondary batteries and improves their weight-to-weight energy density. Furthermore, the three-dimensional framework structure of nanocellulose has tiny nanopores that prevent current leakage, allowing separators to possess excellent electrolyte infiltration and retention properties as well as excellent voltage breakdown resistance.

[0171] In some embodiments, the nanocellulose may comprise at least one of unmodified nanocellulose (also known as hydroxynanocellulose) and modified nanocellulose, and optionally is modified nanocellulose.

[0172] Modified nanocellulose is nanocellulose that simultaneously contains hydroxyl groups and modifying groups. In some embodiments, the modified nanocellulose contains modifying groups, which may include at least one of amino groups, carboxyl groups, aldehyde groups, sulfonic acid groups, boric acid groups, and phosphate groups, and optionally at least one of sulfonic acid groups, boric acid groups, and phosphate groups.

[0173] When nanocellulose contains the above-mentioned specific modified groups, it effectively improves the heat resistance of the separator, improving the thermal stability of the secondary battery, while also improving the adhesive strength between the coating layer and the porous substrate. When nanocellulose contains the above-mentioned specific modified groups, it is advantageous for the nanocellulose and organosilicone particles to overlap and connect to form an integrated effect, thereby allowing the coating layer to have a more stable spatial network structure, improving the separator's electrolyte penetration and retention properties, and improving the separator's ionic conductivity and voltage breakdown characteristics. Furthermore, the presence of the modified groups can reduce the proportion of hydroxy groups, which can impart an appropriate viscosity to the coating layer slurry, making it easier to apply, thereby improving separator production efficiency and coating layer uniformity.

[0174] In some embodiments, the molar ratio of the modifying group to the hydroxy groups is 1:4 to 4:1, and optionally 2:3 to 7:3. When the molar ratio of the modifying group to the hydroxy groups is within this range, the heat resistance, ionic conductivity, and electrolyte infiltration and retention properties of the separator can be further improved. Furthermore, if the molar ratio of the modifying group to the hydroxy groups is too small, the effect of the modifying group in further improving the heat resistance and ionic conductivity of the separator may be insufficient. If the molar ratio of the modifying group to the hydroxy groups is too large, the separator's electrolyte infiltration and retention properties may be impaired, which may affect the cycle performance and reliability of the secondary battery and may also lead to a decrease in the heat resistance of the separator, thereby effectively avoiding the risk of affecting the improvement effect of the thermal stability of the secondary battery.

[0175] The type of modifying group in nanocellulose can be measured by infrared spectroscopy. For example, the type of modifying group can be identified by measuring the infrared spectrum of the material and identifying the characteristic peaks contained therein. Specifically, infrared spectroscopy analysis of the material can be performed using equipment and methods known in the art. For example, an infrared spectrophotometer (e.g., an IS10 Fourier transform infrared spectrophotometer from Nicolet, USA) is used to perform the test in accordance with GB / T 6040-2019, General Rules for Infrared Spectroscopy Analysis Methods.

[0176] In some embodiments, the material constituting the three-dimensional framework contains sulfonic acid groups, and the content of sulfur element in the material constituting the three-dimensional framework can be 0.1 wt% or more, and optionally 0.2 to 0.5 wt%, based on the total weight of the material constituting the three-dimensional framework. Optionally, the material constituting the three-dimensional framework can include nanocellulose.

[0177] The sulfur content of the materials that make up the three-dimensional framework can be determined by drying the materials, grinding them in a mortar (such as an agate mortar) for 30 minutes, and then measuring them using an X-ray diffractometer (e.g., Miniflex 600-C). The test uses a Cu target, Ni filter, a tube voltage of 40 kV, a tube current of 15 mA, and a continuous scan range of 5° to 80°.

[0178] In some embodiments, the coating layer may further include a non-particulate adhesive. The present application is not particularly limited to the type of non-particulate adhesive, and any known material with good adhesive properties may be used. Optionally, the non-particulate adhesive may include at least one of polyacrylonitrile, acrylic resin, acrylate resin, polyvinyl alcohol, isobutylene-maleic anhydride copolymer, polyacrylamide, sodium carboxymethyl cellulose, carboxymethyl chitosan, sodium alginate, and derivatives thereof. A derivative generally refers to a polymer in which a hydrogen atom or atomic group is replaced with another atom or atomic group.

[0179] In some embodiments, the content of the non-particulate adhesive in the coating layer can be 5 wt % or less with respect to the total weight of the coating layer.

[0180] In some embodiments, the thickness of the coating layer is 4 μm or less, and optionally 0.4 to 3 μm. This allows for a thin coating layer, which reduces the overall thickness of the separator and helps improve the energy density of the secondary battery.

[0181] In some embodiments, the thickness of the porous substrate is 6 μm or less, and optionally 3 to 5 μm. The coating layer of the present application can significantly improve the heat resistance of the separator, thereby allowing the selection of a thinner porous substrate, which helps to improve the energy density of the secondary battery.

[0182] In the present application, the material of the porous substrate is not particularly limited, and any known substrate having good chemical and mechanical stability can be selected. For example, the porous substrate can include at least one of a porous polyolefin resin film (e.g., at least one of polyethylene, polypropylene, and polyvinylidene fluoride), a porous glass fiber, and a porous nonwoven fabric. The porous substrate can be a single-layer film or a multi-layer composite film. When the porous substrate is a multi-layer composite film, the materials of the layers can be the same or different.

[0183] In some embodiments, the separator has a longitudinal heat shrinkage of 4.5% or less at 150° C. for 1 hour, and can optionally be 0.8% to 3%.

[0184] In some embodiments, the separator has a thermal shrinkage rate in the transverse direction at 150° C. for 1 hour of 4.5% or less, and can optionally be 1% to 3%.

[0185] The separator has a low thermal shrinkage rate in both the transverse and longitudinal directions at a high temperature of 150° C., thereby improving the reliability of the secondary battery.

[0186] In some embodiments, the separator has a longitudinal tensile strength of 1600 kg / cm 2 or more, and selectively 1800~4500kg / cm 2 It can be.

[0187] In some embodiments, the separator has a transverse tensile strength of 1600 kg / cm 2 or more, and selectively 1800~4500kg / cm 2 It can be.

[0188] The separator has high tensile strength in both the transverse and longitudinal directions, which reduces the probability of the separator being damaged when the secondary battery expands, thereby improving the reliability of the secondary battery.

[0189] In some embodiments, the separator's wet length is 20 mm or more, and can optionally be 30 to 80 mm.

[0190] In some embodiments, the wetting speed of the separator is 2 mm / s or more, and optionally can be 3 to 10 mm / s.

[0191] When the separator has good electrolyte penetration and retention properties, the ionic conductivity of the separator and the capacity of the secondary battery can be improved.

[0192] In some embodiments, the separator has an air permeability of 350 s / 100 mL or less, and optionally 100 to 270 s / 100 mL. The separator has good air permeability, which can improve the ionic conductivity and the capacity of the secondary battery.

[0193] In some embodiments, the ionic conductivity of the separator is 0.5 mS / cm or more, and can optionally be 0.55 to 0.98 mS / cm.

[0194] The heat shrinkage rate, tensile strength, and air permeability of the separator all have meanings known in the art and can be measured by methods known in the art, for example, by referring to GB / T 36363-2018.

[0195] The separator wetting length and wetting rate both have meanings known in the art and can be measured by methods known in the art. In an exemplary test method, a separator is cut into a 5 mm wide and 100 mm long sample, fixed at both ends, and placed horizontally. 0.5 mg of electrolyte is dropped onto the center of the sample. After a predetermined time (1 min in this application), the sample is photographed and the diffusion length of the electrolyte is measured to obtain the separator wetting length and wetting rate. To improve accuracy, multiple samples (e.g., 5 to 10 samples) are tested and the average values ​​are calculated to obtain test results. The electrolyte is prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, and then dissolving thoroughly dried LiPF6 in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0196] The ionic conductivity of the separator can be measured by electrochemical impedance spectroscopy. Specifically, the separator is cut into wafers of a certain area, dried, and then placed between two stainless steel electrodes. After absorbing a sufficient amount of electrolyte, the wafers are sealed to form coin cells, and AC impedance spectroscopy is performed.

[0197] The parameters of the coating layer of the separator (e.g., thickness) are all parameters of the coating layer on one side of the porous substrate. When coating layers are provided on both sides of the porous substrate, it is considered that the parameters of the coating layer on either side satisfy the present application and fall within the scope of protection of the present application. Preparation method

[0198] A second aspect of an embodiment of the present application provides a method for producing the separator of the first aspect of the present application, the method comprising the steps of: providing a porous substrate; kneading organosilicone particles and an adhesive, and then adding a material for constituting a three-dimensional skeletal structure and a solvent and uniformly mixing them to prepare a coating layer slurry; and applying the coating layer slurry to at least one surface of the porous substrate and drying it to obtain a separator, wherein the separator comprises a porous substrate and a coating layer provided on at least one surface of the porous substrate, the coating layer comprising a three-dimensional skeletal structure and organosilicone particles, and at least a portion of the organosilicone particles are filled in the three-dimensional skeletal structure.

[0199] In the manufacturing method according to the embodiment of the present application, first, organic silicone particles and an adhesive are kneaded together, and then a material for forming a three-dimensional skeletal structure (for example, at least one of linear, rod-shaped, tubular, and rod-shaped materials) is added, thereby forming a three-dimensional skeletal structure and also allowing at least a portion of the organic silicone particles to be filled into the three-dimensional skeletal structure.

[0200] Organosilicone particles having structural units represented by formula (a) are commercially available.

[0201] Organosilicone particles containing the first structural unit, the second structural unit, and / or the third structural unit can be obtained according to the production method according to the embodiments of the present application.

[0202] In some embodiments, a method for producing organosilicone particles can include providing a first monomer, a second monomer, and / or a third monomer; mixing the first monomer, the second monomer, and / or the third monomer, and causing a polymerization reaction under the influence of an initiator to produce the organosilicone particles.

[0203] The first monomer, the second monomer, and the third monomer are used to form the above-mentioned first structural unit, the second structural unit, and the third structural unit of the present application, respectively.

[0204] Illustratively, the first monomer can include one or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacryloyloxypropyl hepta iso-butyl polysilsesquioxane, methacryloyloxypropyl heptaoctyl polysilsesquioxane, and acryloyloxypropyl cage-type polysilsesquioxane, acryloyloxypropyl hepta iso-butyl polysilsesquioxane.

[0205] Illustratively, the second monomer may include one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, s-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0206] Illustratively, the third monomer may include acrylonitrile and / or methacrylonitrile.

[0207] In some embodiments, the step of mixing the first monomer, the second monomer, and / or the third monomer and initiating a polymerization reaction under the action of an initiator to produce organosilicone particles specifically includes adding and mixing the first monomer, the second monomer, and / or the third monomer to a solvent and an emulsifier to form a mixed system, adding an initiator to the mixed system, and initiating a polymerization reaction under the action of the initiator to produce organosilicone particles.

[0208] In the present invention, the copolymerization of multiple monomers can be carried out by emulsion polymerization, which is a more convenient polymerization method. Of course, other polymerization methods, such as solution polymerization and suspension polymerization, can also be used, and the process parameters used in the polymerization process can be selected from those commonly used in the art, and therefore, further explanation is omitted here.

[0209] In some examples, the emulsifier can include one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl diphenyl ether disulfonate, and ammonium ethoxylated alkylphenol sulfate.

[0210] In some embodiments, the weight percentage of the emulsifier may be 0.1% to 5% relative to the total weight of the first monomer, the second monomer, and the third monomer. When the weight percentage of the emulsifier is in this range, the first monomer, the second monomer, and the third monomer can be emulsified and dispersed in a solvent to form a relatively uniform system.

[0211] In some examples, the initiator can include potassium persulfate and / or ammonium persulfate.

[0212] In some embodiments, the weight percentage of the initiator may be 0.15% to 1% relative to the total weight of the first monomer, the second monomer, and the third monomer. When the weight percentage of the initiator is in this range, sufficient polymerization is achieved.

[0213] In some embodiments, the solvent may include water, such as deionized water.

[0214] In one specific example, the method for preparing organosilicone particles involves mixing deionized water, an emulsifier, a first monomer, a second monomer, and / or a third monomer, and stirring them uniformly to obtain a prepolymer solution. The emulsifier and deionized water are then added to a container and emulsified by stirring for 30 to 60 minutes to obtain a uniform, stable emulsion. The emulsion is then slowly added dropwise to the prepolymer solution and the initiator solution (for example, the initiator potassium sulfate and / or ammonium persulfate may be dissolved in deionized water to form a solution). After the addition is complete, the temperature is raised to 90 to 110°C and kept at that temperature for 0.5 hours to allow the reaction to occur. The mixture is then cooled to 40°C, the pH is adjusted to 7 to 8 with aqueous ammonia, and the mixture is filtered, discharged, and dried to produce organosilicone particles.

[0215] In some embodiments, the solvent used in preparing the coating layer slurry may be water, for example, deionized water.

[0216] In some embodiments, the coating layer slurry may further include other ingredients, such as dispersants, wetting agents, adhesives, and the like.

[0217] In some embodiments, the material constituting the three-dimensional framework structure can include at least one of an organic material and an inorganic material. Optionally, the organic material can include at least one of nanocellulose, polytetrafluoroethylene nanofiber, and polyamide nanofiber. Optionally, the inorganic material can include at least one of halloysite nanotubes, alumina nanorods, boehmite nanorods, silica nanorods, and glass fibers.

[0218] In some embodiments, the material comprising the three-dimensional scaffold structure can include nanocellulose.

[0219] In some embodiments, nanocellulose can be obtained by a method including providing a cellulose powder having a whiteness of 80% or more, mixing the resulting cellulose powder with a modifying solution to react, washing to remove impurities, adjusting the pH to neutral, and grinding and cutting to obtain nanocellulose.

[0220] Alternatively, the cellulose powder with a whiteness of 80% or more may be commercially available or may be obtained by chemical methods (e.g., acid hydrolysis, alkali treatment, Tempo catalytic oxidation), biological methods (e.g., enzyme treatment), mechanical methods (e.g., ultrafine grinding, ultrasonic crushing, high-pressure homogenization), etc. Fiber raw materials for preparing the cellulose powder with a whiteness of 80% or more may include at least one of plant fibers such as cotton fibers (e.g., cottonseed fiber, cottonwood fiber), hemp fibers (e.g., sisal fiber, ramie fiber, jute fiber, flax fiber, hemp fiber, abaca fiber, etc.), palm fiber, wood fiber, bamboo fiber, and grass fiber.

[0221] In some embodiments, the cellulose powder having a whiteness of 80% or more can be produced by opening a fiber raw material, removing debris, and then steaming the fiber raw material in an alkaline solution (e.g., an NaOH aqueous solution, the concentration of which can be 4 wt% to 20 wt%, optionally 5 wt% to 15 wt%), followed by sequentially washing the raw material with water to remove impurities (e.g., washing three to six times), bleaching (e.g., with sodium hypochlorite and / or hydrogen peroxide), pickling to remove impurities, washing the raw material with water to remove impurities, removing water, and flash drying to obtain a cellulose powder.

[0222] In some embodiments, the denaturing solution may be an acid solution (e.g., aqueous sulfuric acid, aqueous boric acid, aqueous phosphoric acid, aqueous acetic acid) or an alkaline solution (e.g., organic solvent urea solution). Optionally, the denaturing solution is an acid solution.

[0223] Alternatively, the concentration of the acid solution may be 5 wt% to 80 wt%. When a sulfuric acid aqueous solution is used as the modifying solution, the concentration of the acid solution may be 40 wt% to 80 wt%, thereby obtaining cellulose powder having sulfonic acid groups. When a boric acid aqueous solution is used as the modifying solution, the concentration of the acid solution may be 5 wt% to 10 wt%, thereby obtaining cellulose powder having boric acid groups. When a phosphoric acid aqueous solution is used as the modifying solution, the concentration of the acid solution may be 45 wt% to 75 wt%, thereby obtaining cellulose powder having phosphoric acid groups. When an acetic acid aqueous solution is used as the modifying solution, the concentration of the acid solution may be 40 wt% to 80 wt%, thereby obtaining cellulose powder having carboxylic acid groups.

[0224] Alternatively, the urea organic solvent solution may be a urea xylene solution, which can provide a cellulose powder having amine groups.

[0225] In some embodiments, optionally, the weight ratio of cellulose powder to the modification solution may be 1:2.5 to 1:50, optionally 1:5 to 1:30.

[0226] When a sulfuric acid aqueous solution is used as the modifying solution, the mass ratio of the cellulose powder to the acid solution may be 1:5 to 1:30. When a boric acid aqueous solution is used as the modifying solution, the mass ratio of the cellulose powder to the acid solution may be 1:20 to 1:50. When a phosphoric acid aqueous solution is used as the modifying solution, the mass ratio of the cellulose powder to the acid solution may be 1:5 to 1:30. When an acetic acid aqueous solution is used as the modifying solution, the mass ratio of the cellulose powder to the acid solution may be 1:5 to 1:30. When a urea organic solvent solution is used as the modifying solution, the mass ratio of the cellulose powder to the urea organic solvent solution may be 1:4 to 1:40.

[0227] In some embodiments, when the modifying solution is an acid solution, the reaction can be carried out under conditions of 80°C or below, optionally under conditions of 30°C to 60°C, and the reaction time between the cellulose powder and the modifying solution can be 0.25 hours to 3 hours, optionally 0.5 hours to 1.8 hours.

[0228] In some embodiments, when the modifying solution is an alkaline solution, the reaction may be carried out at 100°C to 145°C, and the reaction time between the cellulose powder and the modifying solution may be 0.5 hours to 3.5 hours.

[0229] In some embodiments, grinding may be performed using a grinder, and cutting may be performed using a high-pressure homogenizer. By adjusting the grinding parameters of the grinder (e.g., grinding frequency, grinding time, etc.) and the cutting parameters of the high-pressure homogenizer, nanocellulose having different average diameters and / or different average lengths can be obtained.

[0230] In some embodiments, a coater can be used to apply the slurry for the coating layer. The type of coater is not particularly limited in the present application, and for example, a commercially available coater can be used. The coater includes a gravure roll for transferring the slurry to the porous substrate.

[0231] In some embodiments, the coating layer slurry can be applied by transfer coating, spin spraying, dip coating, or the like.

[0232] Parameters such as some raw materials used in the manufacturing method of the separator and their contents can be referenced for the separator of the first aspect of the embodiment of the present application, and a description thereof will be omitted here.

[0233] Unless otherwise specified, each of the raw materials used in the manufacturing method of the separator is commercially available. secondary battery

[0234] A third aspect of an embodiment of the present application provides a secondary battery.

[0235] A secondary battery, also known as a secondary battery or storage battery, is a battery that can be used continuously after discharging by activating the active material through charging. Typically, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet and serves to prevent short circuits between the positive electrode and the negative electrode while allowing active ions to pass through.

[0236] The present application does not particularly limit the type of secondary battery. For example, the secondary battery may be a lithium ion battery, a sodium ion battery, a lithium metal battery, a sodium metal battery, etc., and in particular, the secondary battery may be a lithium ion battery.

[0237] A secondary battery according to a third aspect of the present invention includes a separator according to the first aspect of the present invention or a separator manufactured by the method according to the second aspect of the present invention, the separator being spaced between a positive electrode sheet and a negative electrode sheet. Optionally, the separator has a coating layer according to the present invention on at least the side of the separator closest to the negative electrode sheet. This allows the secondary battery according to the present invention to combine high energy density, high thermal stability, long cycle life, and good dynamic performance. [Positive electrode sheet]

[0238] In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on one or both of the surfaces of the positive electrode current collector.

[0239] When the secondary battery is a lithium ion battery, the positive electrode active material can include, but is not limited to, at least one of lithium transition metal oxides, lithium-containing phosphates, and their modified compounds. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and at least one of their modified compounds. Examples of lithium-containing phosphates include, but are not limited to, lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and at least one of their modified compounds.

[0240] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium ion battery can include at least one of lithium transition metal oxides and their modified compounds with the general formula Li a Ni b Co c M d O e A f where 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.

[0241] As an example, the positive electrode active material used in the lithium ion battery is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may contain at least one of O2, LiFePO4, and LiMnPO4.

[0242] When the secondary battery is a sodium ion battery, the positive electrode active material can include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (e.g., phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue-based materials.

[0243] For example, the positive electrode active materials used in sodium ion batteries are NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, general formula X p M' q (PO4) r O x Y 3-x The compound may include at least one material of the general formula X p M' q (PO4) r O x Y 3-x In, 0 <p≦4、0<q≦2、1≦r≦3、0≦x≦2であり、XはH + , Li + , Na + , K. + and NH 4+M' is a transition metal cation, and is optionally at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn; and Y is a halogen anion, and is optionally at least one of F, Cl, and Br.

[0244] The modified compounds of the above-mentioned positive electrode active materials are obtained by doping and / or surface-coating the positive electrode active materials.

[0245] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. Although the present application does not particularly limit 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.

[0246] In some embodiments, the positive electrode film layer may further include a positive electrode adhesive. Although the type of the positive electrode adhesive is not particularly limited in the present application, 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.

[0247] In some embodiments, the positive electrode current collector may be a metal foil piece or a composite current collector. An example of the metal foil piece is aluminum foil. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric 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 polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0248] The positive electrode film layer is typically formed by applying a positive electrode slurry to a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive, and any other components in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). [Negative electrode sheet]

[0249] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has opposite surfaces in its thickness direction, and the negative electrode film layer is provided on one or both of the surfaces of the negative electrode current collector.

[0250] The negative electrode active material may be any negative electrode active material known in the art for secondary batteries. Examples of the negative electrode active material include, but are not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloy materials.

[0251] In some embodiments, the negative electrode film layer optionally further includes a negative electrode conductive agent. The type of the negative electrode conductive agent is not particularly limited in the present application, and 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.

[0252] In some embodiments, the negative electrode film layer optionally further includes a negative electrode adhesive. The type of the negative electrode adhesive is not particularly limited in the present application, and the negative electrode adhesive may include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0253] In some embodiments, the negative electrode membrane layer optionally further includes other additives, such as a thickener such as sodium carboxymethyl cellulose (CMC) or a PTC thermistor material.

[0254] In some embodiments, the negative electrode current collector may be a metal foil piece or a composite current collector. An example of the metal foil piece is copper foil. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric 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 polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0255] The negative electrode film layer is typically formed by applying a negative electrode slurry to a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing the negative electrode active material, optional conductive agent, optional adhesive, and optional other additives in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0256] The negative electrode sheet does not exclude additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet is sandwiched between the negative electrode current collector and the negative electrode film layer and further includes a conductive primer layer (e.g., composed of a conductive agent and an adhesive) provided on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet of the present application further includes a protective layer covering the surface of the negative electrode film layer. [Electrolyte]

[0257] During the charge and discharge process of the secondary battery, active ions are inserted and removed between the positive electrode sheet and the negative electrode sheet, and the electrolyte serves to conduct the active ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of electrolyte, and it can be selected according to actual needs.

[0258] The electrolyte solution includes an electrolyte salt and a solvent, and the types of the electrolyte salt and the solvent are not particularly limited and can be selected according to actual needs.

[0259] When the secondary battery is a lithium-ion battery, by way of example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium difluorosulfonylimide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium disoxalate borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorodisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0260] When the secondary battery is a sodium-ion battery, by way of example, the electrolyte salt may include, but is not limited to, at least one of sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium difluorosulfonylimide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalyl borate (NaDFOB), sodium disoxalyl borate (NaBOB), sodium difluorophosphate (NaPOF), sodium difluorodisalyl phosphate (NaDFOP), and sodium tetrafluorooxalyl phosphate (NaTFOP).

[0261] By way of example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0262] In some embodiments, the electrolyte solution optionally further includes additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, or an additive that improves the low-temperature power performance of the battery.

[0263] In some embodiments, the positive electrode sheet, separator, and negative electrode sheet can be wound and / or stacked to form an electrode assembly.

[0264] In some embodiments, the secondary battery may include an exterior case that is used to seal the electrode assembly and the electrolyte.

[0265] In some embodiments, the exterior of the secondary battery may be a hard package such as a hard plastic case, an aluminum case, or a steel case. The exterior of the secondary battery may be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0266] The present application is not particularly limited to the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows a secondary battery 5 having a rectangular structure as an example.

[0267] In some embodiments, as shown in FIG. 2 , the exterior may include a housing 51 and a cover plate 53. The housing 51 includes a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate together form a storage cavity. The housing 51 has an opening communicating with the storage cavity, and the cover plate 53 covers the opening to close the storage cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process and / or a stacking process. The electrode assembly 52 is packaged in the storage cavity. The electrode assembly 52 is impregnated with an electrolyte. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and can be adjusted as needed.

[0268] Methods for manufacturing the secondary battery of the present application are well known. In some embodiments, a secondary battery can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be wound and / or stacked to form an electrode assembly, which can then be placed in a housing, dried, and then injected with an electrolyte. The secondary battery can then be obtained by vacuum sealing, standing, forming, shaping, and other processes.

[0269] In some embodiments, the secondary battery according to the present application may be assembled into a battery module, and the battery module may include multiple secondary batteries, the specific number of which may be adjusted according to the application and capacity of the battery module.

[0270] Fig. 3 is a schematic diagram of an example battery module 4. As shown in Fig. 3, in the battery module 4, the plurality of secondary batteries 5 may be arranged in order along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed with fasteners.

[0271] Optionally, the battery module 4 may further include a case having an accommodating space for accommodating a plurality of secondary batteries 5.

[0272] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0273] 4 and 5 are schematic diagrams of an example battery pack 1. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper box 2 and a lower box 3, and the upper box 2 is disposed over the lower box 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner. power consumption equipment

[0274] A fourth aspect of the present embodiment provides a power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the present embodiment. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device, or as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf car, an electric truck, etc.), a train, a ship, a satellite, an energy storage system, etc.

[0275] A power consuming device can select a secondary battery, a battery module, or a battery pack according to its usage needs.

[0276] 6 is a schematic diagram of an example power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, which may employ a battery pack or battery module to meet the high power and high energy density requirements of the power consuming device.

[0277] Other examples of power consuming devices include mobile phones, tablet computers, laptop computers, etc. These power consuming devices are generally required to be thin and can use secondary batteries as their power source. Example

[0278] The following examples are provided to more specifically describe the contents of the present application, but these examples are merely illustrative and will be apparent to those skilled in the art to make various modifications and variations within the scope of the disclosure of the present application. All parts, percentages, and ratios described in the following examples are by weight and are not particularly limited. All reagents used in the examples are commercially available or may be synthesized according to conventional methods and can be used as is without further treatment. All devices used in the examples are commercially available. Preparation of nanocellulose

[0279] The cotton linters are opened using a cotton opener to remove debris, then steamed for 2 hours at 150°C using a 5 wt% NaOH aqueous solution, followed by washing with water to remove impurities (three washings), bleaching with sodium hypochlorite, washing with dilute hydrochloric acid to remove impurities, washing with water to remove impurities (one washing), removing the water, and air drying, to obtain cotton cellulose powder with a whiteness of 85% or more.

[0280] 1 kg of the obtained cotton cellulose powder was mixed with 30 kg of 60 wt% aqueous sulfuric acid solution and reacted at 55°C to 60°C for 0.5 to 0.8 hours. After the reaction was completed, impurities were removed by washing with water (three times), filtered, and acid and impurities were removed sequentially. The pH was then adjusted to neutral with a 10 wt% aqueous NaOH solution, after which the mixture was polished with a polishing machine and then cut into nanoscale pieces using a high-pressure homogenizer to obtain nanocellulose with sulfonic acid group-modified groups, and the molar ratio of sulfonic acid groups to surface hydroxyl groups was 2:3 to 7:3.

[0281] During the production process, nanocellulose with different average diameters and / or different average lengths can be obtained by adjusting the reaction concentration, reaction time, grinder processing parameters, and high-pressure homogenizer equipment cutting parameters, etc.

[0282] The molar ratio of modifying groups to surface hydroxyl groups in nanocellulose can be measured in accordance with the phthalic anhydride method in GB / T 12008.3-2009 by testing the hydroxyl values ​​(the number of milligrams of potassium hydroxide equivalent to the hydroxyl group content in the sample) of raw cellulose and nanocellulose, respectively, in mgKOH / g, which is then converted to mmol / g to obtain the hydroxyl group content. Subtracting the hydroxyl group content of nanocellulose from the hydroxyl group content of raw cellulose gives the modifying group content (i.e., the content of modified hydroxyl groups), from which the molar ratio of modifying groups to hydroxyl groups can be calculated. Example 1 Separator manufacturing

[0283] A PE porous substrate having a thickness of 4.7 μm is provided. Production of organosilicone particles

[0284] 1400g of deionized water and 7g of sodium dodecyl sulfate were added to a 5L three-neck flask, and emulsified by stirring at 1500 r / min for 30 minutes to obtain a uniform and stable emulsion. Then, 645.68g of methyl acrylate, 79.59g of acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane (the molar ratio of methyl acrylate, acrylonitrile, and methacryloyloxypropyl cage-type polysilsesquioxane was 15:3:2) were added in sequence, and the mixture was stirred at 1500 r / min for 30 minutes to obtain a uniform prepolymer.

[0285] Add 3g of emulsifier and 1000g of deionized water to a dried three-neck flask and emulsify by stirring at high speed for 30 minutes until a uniform and stable emulsion is obtained. Then, using a peristaltic pump, slowly add the prepolymer and initiator solution (3g of initiator, potassium persulfate, dissolved in 30g of deionized water to form a solution) prepared in the previous step. After the addition is complete, the temperature is raised to 90°C and kept at that temperature for 0.5 hours to allow the reaction to proceed. The mixture is then cooled to 40°C and the pH is adjusted to 7-8 with aqueous ammonia. After that, the mixture is filtered, discharged, and dried to produce organosilicone particles.

[0286] To prepare the coating layer slurry, the silicone granules and acrylic resin adhesive were mixed together, followed by the addition of nanocellulose and an appropriate amount of deionized water. The mass ratio of the organic silicone particles, nanocellulose, and adhesive was 85:11:4.

[0287] Coating: The prepared coating layer slurry is applied to both sides of the PE porous substrate using a coater, and then dried and slit to obtain a separator. Positive electrode sheet manufacturing

[0288] Positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), conductive carbon black (Super P), and adhesive polyvinylidene fluoride (PVDF) are uniformly mixed in a mass ratio of 96.2:2.7:1.1 with an appropriate amount of solvent N-methylpyrrolidone (NMP) to obtain a positive electrode slurry. The positive electrode slurry is then applied to a positive electrode current collector aluminum foil, and the positive electrode sheet is obtained through processes such as drying, cold pressing, slitting, and cutting. Manufacture of negative electrode sheets

[0289] The negative electrode active material, artificial graphite, the conductive agent, carbon black (Super P), the adhesive, styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC), are uniformly mixed in a mass ratio of 96.4:0.7:1.8:1.1 with an appropriate amount of deionized water as a solvent to obtain a negative electrode slurry. The negative electrode slurry is then applied to copper foil as a negative electrode current collector, and a negative electrode sheet is obtained through the processes of drying, cold pressing, slitting, and cutting. Preparation of electrolyte

[0290] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:30:40 to obtain an organic solvent, and thoroughly dried LiPF6 is dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L. Secondary battery manufacturing

[0291] The positive electrode sheet, separator, and negative electrode sheet are stacked in order and wound to obtain an electrode assembly. The electrode assembly is then placed in an aluminum plastic film exterior, dried, and then an electrolyte is injected. After vacuum sealing, standing, chemical formation, shaping, and other processes, a small soft-packaged secondary battery with a capacity of 4240mAh is obtained. Examples 2 to 13

[0292] The secondary battery was manufactured using a method similar to that of Example 1, with the difference being that the volume distribution particle size Dv50 of the organosilicone particles and / or the average diameter and average length of the nanocellulose used to manufacture the separator were different, and the specific parameters are shown in Tables 1 and 2. The volume distribution particle size Dv50 of the organosilicone particles can be adjusted by physical shearing such as grinding or high-speed dispersion. Examples 14 to 20

[0293] The secondary battery was manufactured by a method similar to that of Example 1, except that the organosilicon particles used to manufacture the separator were different. The organosilicon particles used in Examples 14 to 19 were manufactured by a method similar to that of Example 1, except that at least one of the raw material components and the content thereof was adjusted, and the specific parameters are shown in Tables 1 and 2. Examples 21 to 25

[0294] The secondary battery was manufactured in a manner similar to that of Example 1, except that the content of organosilicon particles and / or nanocellulose used in the manufacture of the separator was different. The specific parameters are shown in Tables 1 and 2. Comparative Example 1

[0295] The secondary battery was manufactured in a similar manner to Example 1, except that primary particles of alumina (with a volume average particle size Dv50 of approximately 500 nm) were used instead of organosilicone particles in the separator manufacturing process. To prepare the coating layer slurry, alumina, nanocellulose, and acrylic resin were added to deionized water as a solvent in appropriate proportions and mixed uniformly to obtain the coating layer slurry. Testing section (1) Separator heat shrinkage test

[0296] Sample preparation: The separator prepared above is punched out into samples 50 mm wide and 100 mm long using a press, and five parallel samples are taken. These are placed on A4 paper and fixed in place, and the A4 paper containing the samples is then placed on cardboard with a thickness of 1 mm to 5 mm.

[0297] Sample test: Place an A4 sheet of paper on top of a piece of cardboard in a blast oven, set the oven temperature to 150°C, and wait 30 minutes for the temperature to reach the set temperature and stabilize. Start timing, and after the set time (1 hour in this application) is reached, measure the length and width of the separator, and mark the values ​​as a and b, respectively.

[0298] Calculation of heat shrinkage rate: Heat shrinkage rate in machine direction (MD) = [(100-a) / 100] x 100%, Heat shrinkage rate in transverse direction (TD) = [(50-b) / 50] x 100%, The average value of five parallel samples is the test result. (2) Testing the heater case of a secondary battery

[0299] At 25°C, the rechargeable batteries were charged at a constant current of 1C to 4.2V, and then continued constant voltage charging until the current fell below 0.05C. After allowing to stand for 5 minutes, each clamped rechargeable battery was tested in a DHG-9070A DHG series high-temperature oven. The temperature was raised from room temperature to 80°C ±2°C at a rate of 5°C / min and held for 30 minutes. The temperature was then increased at a rate of 5°C / min in 5°C increments, and the oven temperature was maintained for 30 minutes. The surface temperature of the rechargeable battery was monitored during the heating process; the oven temperature at which the temperature began to rise rapidly was the failure temperature of the rechargeable battery's heat box. A higher failure temperature of the rechargeable battery's heat box indicated better thermal stability. For accuracy, the test results were averaged over five parallel samples. (3) Testing the cycle performance of secondary batteries

[0300] At 45°C, the secondary battery was charged to 4.2V at a constant current of 1C. Constant voltage charging was continued until the current dropped below 0.05C. At this point, the secondary battery was fully charged. The charge capacity at this point was recorded, i.e., the first-cycle charge capacity. After allowing the secondary battery to stand for 5 minutes, it was discharged to 2.8V at a constant current of 1C. This constitutes one charge-discharge cycle. The discharge capacity at this point was recorded, i.e., the first-cycle discharge capacity. The secondary battery was subjected to a cycle charge-discharge test according to the above method, and the discharge capacity after one cycle was recorded. The capacity retention rate (%) of the secondary battery after 1000 cycles at 45°C = discharge capacity after 1000 cycles / discharge capacity at first cycle × 100%. For accuracy, the test results were calculated by averaging five parallel samples.

[0301] [Table 1A] [Table 1B]

[0302]

Table 2

[0303] As is clear from Table 1 and Table 2, by providing a coating layer containing a three-dimensional skeleton structure and organic silicone particles on the surface of the separator porous substrate, and filling at least a part of the organic silicone particles into the three-dimensional skeleton structure, the separator can be provided with high heat resistance, and the secondary battery can have high energy density, high thermal stability and long cycle life.

[0304] As is further clear from Table 1 and Table 2, by further adjusting the parameters of the nanocellulose and the organic silicone particles, and satisfying 0 < D1 / (d1 / √6) ≤ 1 and 0 < d1 / (L1 / √2), the performance of the separator and the secondary battery can be improved better. Moreover, by further adjusting one or more ranges of D1 / (d1 / √6), d1 / (L1 / √2), D1, d1, L1, the comprehensive performance of the separator and the secondary battery can be further improved.

[0305] As can be further seen from Table 1 and Table 2, by further adjusting the mass content of the nanocellulose and the organic silicone particles, the comprehensive performance of the separator and the secondary battery can be improved better.

[0306] Note that the present application is not limited to the above embodiments. The above embodiments are illustrative, and those having a configuration substantially the same as the technical idea and having the same effects in the technical scope of the present application are included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications conceived by those skilled in the art are applied to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application.

Claims

1. A porous substrate and a coating layer provided on at least one surface of the porous substrate, the coating layer comprises a three-dimensional framework and organosilicone particles; At least a portion of the organosilicone particles are packed into the three-dimensional framework. Separator.

2. The volume distribution particle size Dv50 of the organosilicone particles is １ and the unit is nm. The average diameter of the material constituting the three-dimensional framework is D １ and the unit is nm. The average length of the material constituting the three-dimensional framework is L １ and the unit is nm, 0<D １ / (d １ / √6)≦1 and 0<d １ / (L １ / √2)≦1, The separator according to claim 1 .

3. 0.04≦D １ / (d １ / √6)≦0.85, and optionally 0.05≦D １ / (d １ / √6)≦0.65, and / or 0.04≦d １ / (L １ / √2)≦0.9, and optionally 0.08≦d １ / (L １ / √2)≦0.8, The separator according to claim 1 or 2.

4. The volume distribution particle size Dv50 of the organosilicone particles is １ Let d １ is less than 2000 nm, optionally between 275 and 1500 nm; and / or The average diameter of the material constituting the three-dimensional framework is D １ And D １ is 50 nm or less, optionally 10 to 42 nm, and / or The average length of the material constituting the three-dimensional framework is L １ And L １ is 100 to 3500 nm, optionally 400 to 3000 nm; The separator according to claim 1 .

5. The organosilicone particles satisfy at least one of the following conditions (1) to (6): (1) The topography of the organosilicone particles includes spherical and / or near-spherical shapes; (2) the volume distribution particle size Dv90 of the organosilicone particles is 3500 nm or less, and optionally 800 to 2500 nm; (3) The specific surface area of ​​the organosilicone particles is S, and its unit is m 2 / g, 5.0m 2 / g≦S≦12.0m 2 / g, and optionally 6.0 m 2 / g≦S≦10.0m 2 / g, (4) The true density of the organosilicone particles is 1.0 to 2.0 g / cm ３ and optionally 1.2 to 1.7 g / cm ３ and (5) The compressed powder density of the organosilicone particles at 30,000 N is 0.3 to 1.5 g / cm ３ and optionally 0.5 to 1.0 g / cm ３ and (6) The number average molecular weight of the organosilicone particles is 20,000 to 80,000, and optionally 30,000 to 50,000; The separator according to claim 1 .

6. The content of the organosilicone particles is 50 wt % or more, and optionally 50-90 wt % based on the total weight of the coating layer; and / or The content of the three-dimensional framework structure is less than 50 wt %, and optionally 8 to 48 wt %, based on the total weight of the coating layer; The separator according to claim 1 .

7. the organosilicone particles include a first structural unit, The first structural unit is represented by formula (I): 【Chemistry 1】 In formula (I), R ２０ ~R ２７ each independently contains one or more of a substituted or unsubstituted C1 to C10 alkyl group and a structural unit represented by formula (I-1), and R ２０ ~R ２７ At least one of the above contains a structural unit represented by formula (I-1): 【Chemistry 2】 In formula (I-1), R ２８ contains one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R ２８ contains a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group, R ２９ comprises a substituted or unsubstituted C1-C10 alkyl group, optionally R ２９ contains a substituted or unsubstituted C3 to C10 alkyl group; The separator according to claim 1 .

8. the organosilicone particles further include a second structural unit and / or a third structural unit, The second structural unit has a structure shown in formula (II): 【Transformation 3】 In formula (II), R １ contains one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R １ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group, R ２ includes one or more of a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, and a substituted or unsubstituted C1 to C20 hydroxyalkyl group, and optionally R ２ contains one or more of a C1 to C12 alkyl group, a C3 to C12 cycloalkyl group, and a C1 to C12 hydroxyalkyl group, The third structural unit is represented by formula (III): 【Chemistry 4】 In formula (III), R ３ contains one or more of a hydrogen atom, a substituted or unsubstituted C1 to C5 alkyl group, and optionally R ３ contains one or more of a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, The separator according to claim 7.

9. The molar content of the first structural unit is A%, where A% is 0<A≦20, and optionally 5≦A≦20, relative to the total molar amount of the first structural unit, the second structural unit, and the third structural unit; and / or The molar content of the second structural unit is B% relative to the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and is 60≦B<100, and optionally 60≦B≦80; and / or The molar content of the third structural unit is C% relative to the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and is 0<C≦20, and optionally 5≦C≦20. The separator according to claim 8.

10. The molar content of the first structural unit is A%, the molar content of the second structural unit is B%, and the molar content of the third structural unit is C%, relative to the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and the organosilicone particles satisfy at least one of the following conditions (1) to (3): (1) 3≦B / C≦16, (2) 3≦B / A≦16, (3) B:C:A is (12-16):(1-4):(1-4), The separator according to claim 8 or 9.

11. The organosilicone particles contain a structural unit represented by formula (a), 【Transformation 5】 In formula (a), R １４ and R １５ are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a hydroxy group, or an amino group, and optionally R １４ and R １５ are each independently selected from a hydrogen atom, a substituted or unsubstituted C1 to C6 alkyl group, a hydroxy group, or an amino group; Optionally, the organosilicone particles comprise one or more of polymethylsiloxane, polydimethylsiloxane, polydiethylsiloxane, polymethylhydroxysiloxane, polymethylaminosiloxane, and derivatives thereof; The separator according to any one of claims 1 to 10.

12. The material constituting the three-dimensional skeletal structure includes at least one of a wire, a rod, a tube, and a rod. The separator according to any one of claims 1 to 11.

13. the aspect ratio of the material constituting the three-dimensional framework is 5 to 150 or less, and optionally 20 to 100 or less; The separator according to any one of claims 1 to 12.

14. the material constituting the three-dimensional framework includes at least one of an organic material and an inorganic material; Optionally, the organic material comprises at least one of nanocellulose, polytetrafluoroethylene nanofibers, and polyamide nanofibers; and optionally, the nanocellulose comprises at least one of cellulose nanofibers, cellulose nanowhiskers, and bacterial nanocellulose; Optionally, the inorganic material comprises at least one of halloysite nanotubes, alumina nanorods, boehmite nanorods, silica nanorods, and glass fibers; The separator according to any one of claims 1 to 13.

15. The material constituting the three-dimensional framework structure includes nanocellulose, and the nanocellulose includes at least one of unmodified nanocellulose and modified nanocellulose; Optionally, the modified nanocellulose comprises a modifying group, the modifying group comprising at least one of an amino group, a carboxyl group, an aldehyde group, a sulfonic acid group, a boric acid group, and a phosphoric acid group, more preferably at least one of a sulfonic acid group, a boric acid group, and a phosphoric acid group; Preferably, the modified nanocellulose comprises hydroxy groups and modifying groups, and the molar ratio of the modifying groups to the hydroxy groups is from 1:4 to 4:1, more preferably from 2:3 to 7:

3. The separator according to any one of claims 1 to 14.

16. the material constituting the three-dimensional skeletal structure contains a sulfonic acid group, and the content of sulfur element in the material constituting the three-dimensional skeletal structure is 0.1 wt % or more, and optionally 0.2 to 0.5 wt %, relative to the total weight of the material constituting the three-dimensional skeletal structure; The separator according to any one of claims 1 to 15.

17. the coating layer further comprises a non-particulate adhesive; Optionally, the content of the non-particulate adhesive in the coating layer is 5 wt % or less based on the total weight of the coating layer; Optionally, the non-particulate adhesive comprises at least one of polyacrylonitrile, acrylic resin, acrylate resin, polyvinyl alcohol, isobutylene-maleic anhydride copolymer, polyacrylamide, sodium carboxymethyl cellulose, carboxymethyl chitosan, sodium alginate, and derivatives thereof; The separator according to any one of claims 1 to 16.

18. the thickness of the porous substrate is 6 μm or less, optionally 3 to 5 μm; and / or The thickness of the coating layer is 4 μm or less, and optionally 0.4 to 3 μm; The separator according to any one of claims 1 to 17.

19. The separator satisfies at least one of the following conditions (1) to (8): (1) the separator has a longitudinal heat shrinkage rate of 4.5% or less at 150°C for 1 hour, and optionally 0.8% to 3%; (2) The separator has a transverse heat shrinkage rate of 4.5% or less at 150°C for 1 hour, and optionally 1% to 3%; (3) The separator has a longitudinal tensile strength of 1600 kg / cm ２ or more, and optionally 1800 to 4500 kg / cm ２ and (4) The separator has a tensile strength of 1600 kg / cm in the transverse direction. ２ or more, and optionally 1800 to 4500 kg / cm ２ and (5) The wet length of the separator is 20 mm or more, and optionally 30 to 80 mm; (6) The wetting speed of the separator is 2 mm / s or more, and optionally 3 to 10 mm / s; (7) The separator has an air permeability of 350 s / 100 mL or less, and optionally 100 to 270 s / 100 mL; (8) The ionic conductivity of the separator is 0.5 mS / cm or more, and optionally 0.55 mS / cm. The separator according to any one of claims 1 to 18.

20. A method for producing the separator of any one of claims 1 to 19, comprising the steps of: providing a porous substrate; a step of kneading the organic silicone particles and the adhesive, and then adding and uniformly mixing a material for forming a three-dimensional skeleton structure and a solvent to prepare a slurry of the coating layer; and applying the slurry of the coating layer to at least one surface of the porous substrate and drying it to obtain a separator. the separator includes a porous substrate and a coating layer provided on at least one surface of the porous substrate; the coating layer comprises a three-dimensional framework and organosilicone particles; The method wherein at least a portion of the organosilicone particles are packed into the three-dimensional framework.

21. 21. A separator comprising the separator of any one of claims 1 to 19 or a separator produced by the method of claim 20. Secondary battery.

22. 22. A power consuming device comprising the secondary battery of claim 21.

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