Separator, battery cell, battery and power consuming device

Abstract

The present application provides separators, battery cells, batteries, and power consuming devices, the separator comprising a group of polymers including at least one of a first polymer and a second polymer, the separator comprising: JPEG2026501684000063.jpg16167

Description

[Technical Field]

[0001] This application relates to the field of batteries, and more particularly to separators, battery cells, batteries, and power consuming devices. [Background technology]

[0002] Due to their characteristics such as high capacity and long life, battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric steamships, electric toy cars, electric toy steamships, electric toy airplanes, and electric tools.

[0003] As the range of battery applications expands, the requirements for battery cell performance are also becoming stricter. However, the cycle performance of current battery cells is poor and needs to be further improved. Summary of the Invention

[0004] The embodiments of the present application have been made in view of the above-mentioned problems, and have an object to provide a separator, a battery cell, a battery, and a power consuming device.

[0005] According to a first aspect of the present application, there is provided a separator comprising a group of polymers including at least one of a first polymer and a second polymer,

[0006] The separator is JPEG2026501684000002.jpg16154

[0007] M represents the mass of the separator without adsorbing the electrolyte, and its unit is g;

[0008] m1 represents the mass of the separator weighed under ambient pressure after being immersed in the electrolyte for 2 hours, and its unit is g;

[0009] m2 represents the mass of the separator weighed under 10,000 N pressure at ambient pressure after the separator has been immersed in the electrolyte for 2 hours, and its unit is g;

[0010] v represents the liquid absorption rate of the separator, and its unit is mg / s;

[0011] λ represents the porosity of the separator.

[0012] As a result, the separator of the embodiment of the present application includes a group of polymers, and the polymers included in the group of polymers have high liquid absorption and liquid retention capabilities, so that the separator has a strong liquid retention capacity and is less likely to extrude the electrolyte during charging and discharging of the battery cell cycle.In addition, the separator has a strong liquid absorption capacity and a fast liquid absorption speed, so that even if a small amount of electrolyte is extruded, it can be quickly re-adsorbed during discharging of the battery cell, thereby increasing the transfer speed of the electrolyte between the separator and the sheet, reducing liquid shortage during charging and discharging cycles, reducing battery polarization, and improving the cycle performance of the battery cell.

[0013] In some embodiments, the separator comprises: JPEG2026501684000003.jpg18156

[0014] As a result, when the separator of the embodiment of the present application satisfies the above conditions, its liquid absorption and retention capabilities can be further improved, further reducing liquid shortage during cycle charge / discharge, reducing battery polarization, and improving the cycle performance of the battery cell.

[0015] In some embodiments, the separator comprises: JPEG2026501684000004.jpg15160

[0016] As a result, when the separator of the embodiment of the present application satisfies the above conditions, its liquid absorption and retention capabilities can be further improved, further reducing liquid shortage during cycle charge / discharge, reducing battery polarization, and improving the cycle performance of the battery cell.

[0017] In some embodiments, the separator comprises:

[0018] JPEG2026501684000005.jpg14155

[0019] As a result, when the separator of the embodiment of the present application satisfies the above conditions, its liquid absorption and retention capabilities can be further improved, further reducing liquid shortage during cycle charge / discharge, reducing battery polarization, and improving the cycle performance of the battery cell.

[0020] In some embodiments, the separator comprises:

[0021] JPEG2026501684000006.jpg11155

[0022] As a result, when the separator of the embodiment of the present application satisfies the above conditions, its liquid absorption and retention capabilities can be further improved, further reducing liquid shortage during cycle charge / discharge, reducing battery polarization, and improving the cycle performance of the battery cell.

[0023] In some embodiments, the separator comprises: v / λ>5.00, and optionally, 5 <v / λ<50である。

[0024] Therefore, when the separator of the embodiment of the present application satisfies the above conditions, the separator has good liquid absorption ability, which is advantageous for improving the absorption rate of the electrolyte, thereby further improving the cycle performance of the battery cell.

[0025] In some embodiments, the mass percentage of the polymer group is 0.1% to 20% of the total mass of the separator. When the mass percentage of the polymer group is in this range, the separator has good liquid absorption and retention capabilities, which is advantageous for further improving the cycle performance of the battery cell.

[0026] In some embodiments, the first polymer and the second polymer each independently include a fluorinated polymer.

[0027] Optionally, the crystallinity of the fluorinated polymer measured by differential scanning calorimetry is Xc1, where 0 < Xc1 ≤ 30%, and the melting temperature of the fluorinated polymer is T m1 in °C, where 0 < T m1 ≤ 140.

[0028] In some embodiments, the glass transition temperature of the fluorinated polymer is T g1 in °C, where -150 ≤ T g1 ≤ 60.

[0029] In some embodiments, the fluorinated polymer includes at least one of the structural units shown in formula (AI) to the structural units shown in formula (AIII). JPEG2026501684000007.jpg31168

[0030] In formula (AI) and formula (AII), R 11 , R 12 , R 13 and R 14 each independently include a hydrogen atom, a fluorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group or a substituted or unsubstituted C1-C3 alkoxy group, and at least one of R 11 , R 12 , R 13 and R 14 includes a fluorine atom. JPEG2026501684000008.jpg31166

[0031] In formula (AIII),

[0032] R 15 includes a single bond, a substituted or unsubstituted C1-C3 alkyl group, p is a positive integer selected from 1 to 3, and n is a positive integer selected from 1000 to 30000.

[0033] In some embodiments, the liquid-retaining polymer further comprises an ether-based polymer, the ether-based polymer is made into a sheet-like structure, and a dynamic frequency scanning test is performed on the sheet-like structure at (T m2 +20)°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve is K1, where 1 < K1 < ∞, and T m2 °C represents the melting temperature of the ether-based polymer. Optionally, 1 < K1 ≤ 100, and more optionally, 1 < K1 ≤ 10.

[0034] In some embodiments, the first polymer and the second polymer each independently contain an ether-based polymer.

[0035] Optionally, the ether-based polymer contains a structural unit represented by formula (BI) and / or a structural unit represented by formula (BII). JPEG2026501684000009.jpg30166

[0036] In formula (BI), R 21 and R 22 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group or a substituted or unsubstituted C1-C3 alkoxy group, and R 23 contains a substituted or unsubstituted C1-C5 alkylene group. JPEG2026501684000010.jpg31166

[0037] In formula (BII), R 24 ~R 27 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group or an ether group, and at least one of R 24 ~R 27 contains a substituted or unsubstituted C1-C3 alkoxy group or an ether group.

[0038] In some embodiments, the first polymer and the second polymer each independently include an ester-based polymer.

[0039] Optionally, the ester-based polymer is manufactured into a sheet-like structure, and a dynamic frequency scanning test is performed on the sheet-like structure at (T m3 +20)°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve is K2, where 1 < K2 < ∞, and T m3 °C represents the melting temperature of the ester-based polymer. Optionally, 1 < K2 ≤ 100, and further optionally, 1 < K2 ≤ 10.

[0040] In some embodiments, the ester-based polymer includes a structural unit represented by formula (CI) and / or a structural unit represented by formula (CII). JPEG2026501684000011.jpg46164

[0041] In formula (CI), R 31 , R 32 and R 33 each independently include a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group, and R 34 includes a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group. JPEG2026501684000012.jpg24165

[0042] In formula (CII), R 35 includes a substituted or unsubstituted C2-C6 methylene group. Optionally, R 35 each independently includes a substituted or unsubstituted C2-C4 methylene group.

[0043] In some embodiments, the first polymer and the second polymer each independently include an aldehyde-ketone polymer.

[0044] Optionally, the aldehyde ketone polymer is formed into a sheet-like structure, and the sheet-like structure is subjected to (T m4 A dynamic frequency scan test is performed at +20°C to obtain a storage modulus G'-loss modulus G" curve, the slope of the storage modulus G'-loss modulus G" curve is K3, and 0.8≦K3<∞; T m4 °C represents the melting temperature of the aldehyde ketone polymer, optionally 0.8≦K3≦100, and further optionally 0.8≦K3≦10.

[0045] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (DI) and / or a structural unit shown in formula (DII): JPEG2026501684000013.jpg39168

[0046] In formula (DI), R 41 contains a single bond, a substituted or unsubstituted C1-C6 methylene group, and R 42 contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group, JPEG2026501684000014.jpg32165

[0047] In formula (DII), R 43 ~R 46 each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from a positive integer.

[0048] In some embodiments, the molecular weight of the liquid-retaining polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0049] In some embodiments, the separator body includes a substrate and the polymer layer is disposed on at least one surface of the substrate.

[0050] In some embodiments, the separator comprises a porous substrate and the polymers are distributed within the pores of the porous substrate.

[0051] In some embodiments, the separator comprises a porous substrate and a polymer layer comprising the polymers disposed on at least one surface of the porous substrate.

[0052] In some embodiments, the coating basis weight of the polymers is 0.5 mg / 1540.25 mm 2 ~5mg / 1540.25mm 2 is.

[0053] According to a second aspect, the present application proposes a battery cell, said battery cell comprising a separator according to any of the embodiments of the first aspect of the present application.

[0054] According to a third aspect, the present application proposes a battery, said battery comprising a battery cell according to any of the embodiments of the second aspect of the present application.

[0055] According to a fourth aspect, the present application proposes a power consuming device, said power consuming device comprising a battery according to any of the embodiments of the third aspect of the present application. [Brief explanation of the drawings]

[0056] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly describes the drawings that need to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without paying creative labor.

[0057] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a battery cell of the present application. [Figure 2] FIG. 2 is an exploded schematic view of an embodiment of the battery cell of FIG. 1. [Figure 3]1 is a schematic diagram of one embodiment of a battery module of the present application. [Figure 4] 1 is a schematic diagram of one embodiment of a battery pack of the present application. [Figure 5] FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4. [Figure 6] 1 is a schematic diagram of one embodiment of a power consuming device that includes a battery cell of the present application as a power source.

[0058] The drawings are not necessarily drawn to scale. [Explanation of symbols]

[0059] 1, battery pack, 2, upper housing, 3, lower housing, 4, battery module,

[0060] 5, battery cell, 51, case, 52, electrode component,

[0061] 53, cover plate,

[0062] 6, power consumption equipment. DETAILED DESCRIPTION OF THE INVENTION

[0063] Hereinafter, detailed descriptions will be given of embodiments specifically disclosing the separator, battery cell, battery, and power consumption device of the present application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0064] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the endpoints and are combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise specified, a numerical range "ab" represents a shorthand notation for any combination of real numbers ab, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5" and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0065] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0066] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, when a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, when a method further includes step (c), it means that step (c) may be added to the method in any order, e.g., 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.

[0067] Unless otherwise specified, the terms "comprise" and "contain" referred to in this application may be open-ended or closed-ended. For example, "comprise" and "contain" may indicate that the composition may further include or contain other ingredients not listed, or may include or contain only the listed ingredients.

[0068] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0069] In this application, the terms "plurality" and "plurality" mean two or more or more kinds.

[0070] The term "alkyl group" encompasses straight-chain and branched alkyl groups. For example, the alkyl group may be a C1-C5 alkyl group, a C1-C4 alkyl group, a C1-C3 alkyl group, or a C1-C2 alkyl group. In some examples, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and the like. The alkyl group may also be optionally substituted. When substituted, the substituent may include a fluorine atom.

[0071] The term "alkoxy group" refers to an alkyl group attached to an oxygen atom by a single bond. For example, the alkoxy group can be a C1-C5 alkoxy group, a C1-C3 alkoxy group, or a C1-C2 alkoxy group. In some embodiments, the alkoxy group can include a methoxy group, an ethoxy group, or a propoxy group. Additionally, the alkoxy group can be optionally substituted.

[0072] The term "halogen atom" refers to fluorine atom, chlorine atom, bromine atom, and the like.

[0073] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (protium, H).

[0074] A battery cell includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. The separator is located between the positive electrode sheet and the negative electrode sheet, separating them. During the charge-discharge cycle of the battery cell, the electrode components undergo volume expansion. This expansion force is particularly high in the later stages of the battery cell's cycle, causing the electrolyte to be pushed out. This slows the separator's absorption rate and makes it difficult for the separator to re-absorb the electrolyte, increasing the risk of electrolyte shortage and bridge rupture. This can deteriorate the cycle performance of the battery cell and shorten the cycle life of the battery cell.

[0075] In view of the above problems, an embodiment of the present application proposes a separator, which includes a polymer group, and the polymer included in the polymer group has high liquid absorption and high liquid retention capacity, so that the separator has a strong liquid retention capacity and is less likely to extrude the electrolyte during charging and discharging of the battery cell cycle. In addition, the separator has a strong liquid absorption capacity and a fast liquid absorption speed, so that even if a small amount of electrolyte is extruded, it can be quickly re-adsorbed during discharging of the battery cell, thereby accelerating the transfer speed of the electrolyte between the separator and the sheet, reducing liquid shortage during charging and discharging cycles, reducing battery polarization, and improving the cycle performance of the battery cell.

[0076] Separator

[0077] According to a first aspect, an embodiment of the present application proposes a separator comprising a group of polymers including at least one of a first polymer and a second polymer, said separator comprising:

[0078] JPEG2026501684000015.jpg16161

[0079] M represents the mass of the separator without adsorbing the electrolyte, and its unit is g;

[0080] m1 represents the mass of the separator weighed under ambient pressure after being immersed in the electrolyte for 2 hours, and its unit is g;

[0081] m2 represents the mass of the separator weighed under an applied force of 10,000 N at ambient pressure after the separator has been immersed in the electrolyte for 2 hours, and its unit is g;

[0082] v represents the liquid absorption rate of the separator, and its unit is mg / s;

[0083] λ represents the porosity of the separator.

[0084] When performing specific calculations in the above formula, only specific numerical values ​​are substituted, and the units of each parameter are not substituted.

[0085] The separator of the embodiment of the present application includes a polymer group, and the polymers included in the polymer group have high liquid absorption and retention capabilities, so that the separator has a strong liquid retention capacity and is less likely to extrude the electrolyte during charging and discharging of the battery cell cycle.The separator also has a strong liquid absorption capacity and a fast liquid absorption rate, so that even if a small amount of electrolyte is extruded, it can be quickly re-adsorbed during discharging of the battery cell.This increases the rate at which the electrolyte is transferred between the separator and the sheet, reduces liquid shortage during charging and discharging cycles, reduces battery polarization, and improves the cycle performance of the battery cell.

[0086] The separator may be manufactured from a substrate and a polymer group, etc. Alternatively, the separator may be derived from a battery cell. The battery cell is disassembled, and the separator that is immersed in the electrolyte of the battery cell is removed, washed with deionized water, and then vacuum-dried at 80°C for 12 hours to obtain the separator, which is then used for separator tests such as mass measurement, liquid absorption rate, and porosity.

[0087] M represents the mass of the separator without adsorbing the electrolyte, and may be understood as the mass of the separator itself. 2 The mixture may be cut into pellets of 1000 kJ / g and the mass thereof may be measured on an electronic balance.

[0088] m1 represents the mass of the separator weighed under ambient pressure after it has been immersed in the electrolyte for 2 hours. Specifically, 2 The pellets are immersed in the electrolyte for 2 hours, then the pellets are taken out and suspended under atmospheric pressure for 2 minutes, after which their mass is measured.

[0089] m2 represents the mass of the separator weighed under the application of a 10,000 N force at ambient pressure after the separator has been immersed in the electrolyte for 2 hours. Specifically, the separator is divided into 10 sheets of 1540.25 mm 2 The separator is cut into pellets, the pellets are immersed in an electrolyte for 2 hours, the pellets are taken out, the pellets are stacked one after another, and a force of 10,000 N is applied under the ambient pressure, and then the mass of the separator is weighed.

[0090] In this application, a standard electrolyte solution is used as a sample for testing. The specific composition of the electrolyte solution may refer to the electrolyte composition in the Examples. For example, the electrolyte solution contains ethylene carbonate EC, methyl ethyl carbonate EMC, and dimethyl carbonate DMC in a volume ratio of 1:1:1, and further contains lithium hexafluorophosphate LiPF6 with a molar concentration of 1 mol / L.

[0091] In the embodiment of the present application, v represents the liquid absorption rate of the separator, which may be detected by the following method, the specific steps of which are as follows:

[0092] Using a pipette, aspirate 1 mL of electrolyte solution.

[0093] Separator 1540.25mm 2 Cut into small pellets, hang them horizontally, and leave them.

[0094] 1 mL of electrolyte solution was drawn up with a pipette and dropped onto the center of the small pellet. Time was started and the time when the wetted radius of the electrolyte solution reached 10 mm was recorded.

[0095] The ratio of the wetting radius and the wetting time is calculated to obtain the liquid absorption rate v.

[0096] In the present application, the standard electrolyte solution is used as a sample for testing, and the specific formulation of the electrolyte solution may be referred to in the Examples.

[0097] In an embodiment of the present application, the porosity of the separator is the ratio of the pore volume of the separator to the total volume of the separator, and may be determined using instruments and methods well known in the art, such as GB / T21650.2-2008 "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion and Gas Adsorption Methods, Part 2: Analysis of Mesopores and Macropores by Gas Adsorption Methods" and ASTM D2873-941 "Standard Test Method for Interior Porosity of Poly(Vinyl Choride) (PVC) Resins by Mercury Intrusion Porosimetry."

[0098] In some embodiments, the separator comprises: JPEG2026501684000016.jpg17160

[0099] When the separator satisfies the above conditions, its liquid absorption and retention capabilities can be further improved, which can further reduce liquid shortage during cycle charge / discharge, reduce battery polarization, and improve the cycle performance of the battery cell.

[0100] For example, JPEG2026501684000017.jpg19170 may be 1.5, 2.0, 2.5, 3.0, 3.2, 3.5, 3.8, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 12, or a range consisting of any two of the above values.

[0101] In some embodiments, the separator comprises: JPEG2026501684000018.jpg18165

[0102] m2-M represents the difference between the mass of the separator weighed under 10,000 N pressure at ambient pressure after immersion in the electrolyte for 2 hours and the mass of the separator without adsorbed electrolyte. That is, m2-M is the amount of liquid remaining in the separator under external action, and can characterize the liquid-holding capacity of the separator.

[0103] m1-M represents the difference between the mass of the separator weighed under ambient pressure after immersion in the electrolyte for 2 hours and the mass of the separator without adsorbed electrolyte. In other words, m1-M is the amount of liquid adsorbed by the separator, and can characterize the liquid absorption capacity of the separator.

[0104] JPEG2026501684000019.jpg17162

[0105] When the separator satisfies the above conditions, it has strong liquid absorption and retention capabilities, reduces liquid shortage during cycle charge / discharge, reduces battery polarization, and improves the cycle performance of the battery cell.

[0106] Selectively, JPEG2026501684000020.jpg11156

[0107] JPEG2026501684000021.jpg15166

[0108] 25.1%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5%, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, 36%, 36.5%, 37%, 37.5%, 38%, 39%, 40%, It may be 41%, 42%, 45%, 46%, 48%, 50%, 52%, 55%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, 95%, 96%, 97%, 98%, 99%, or a range consisting of any two of the above values.

[0109] In some embodiments, the separator comprises: JPEG2026501684000022.jpg17164

[0110] m1-M represents the ratio of the amount of liquid absorbed by the separator to the mass of the separator itself, which can characterize the liquid absorption capacity of the separator and can also represent the amount of electrolyte absorbed by the separator, and can also improve its liquid retention capacity.

[0111] JPEG2026501684000023.jpg14170

[0112] If the separator satisfies the above conditions, the separator has good liquid absorption ability, which is advantageous for improving the absorption rate of the electrolyte, thereby further improving the cycle performance of the battery cell.

[0113] JPEG2026501684000024.jpg15170

[0114] It may be 88%, 90%, 92%, 95%, 96%, 97%, 98%, 99%, 100%, 105%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, 300%, or a range consisting of any two of the above values.

[0115] In some embodiments, the separator comprises: JPEG2026501684000025.jpg15157

[0116] (m2-M) / M represents the ratio of the amount of liquid remaining in the separator under external action to the mass of the separator itself, and can characterize the liquid retention capacity of the separator.

[0117] JPEG2026501684000026.jpg18164

[0118] When the separator satisfies the above conditions, the separator has good liquid retention capacity under pressurized conditions, and the electrolyte adsorbed by the separator is less likely to be pushed out, thereby increasing the migration rate of active ions and further improving the cycle performance of the battery cell.

[0119] JPEG2026501684000027.jpg15161

[0120] 22.5%, 25.1%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5%, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, 36%, 36.5%, 37%, 37.5%, 38%, 39%, 40%, 41%, 42%, 45%, 46%, 48%, 50%, 52%, 55%, 60%, 62%, 65%, 68%, 70%, It may be 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, 95%, 96%, 97%, 98%, 99%, 100%, 105%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, 300%, or a range consisting of any two of the above numerical values.

[0121] In some embodiments, v / λ>5.00, and optionally, 5 <v / λ<50である。

[0122] If the separator satisfies the above conditions, the separator has good liquid absorption ability, which is advantageous for improving the absorption rate of the electrolyte, thereby further improving the cycle performance of the battery cell.

[0123] Illustratively, v / λ may be 5.1, 5.2, 5.5, 6, 6.5, 7, 8, 9, 10, 12, 15, 18, 20, 25, 30, 35, 40, 45, 46, 47, 48, 49, 49.5, 50, 55, or a range consisting of any two of the above values.

[0124] The mass percentage of the polymer group is 0.1% to 20% with respect to the total mass of the separator.

[0125] When the mass percentage of the polymer group is within the above range, the separator has good liquid absorption and retention capabilities, which is advantageous for further improving the cycle performance of the battery cell.

[0126] Illustratively, the mass percentage of the polymer group may be 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%, or a range consisting of any two of the above values.

[0127] The first polymer and the second polymer may comprise the same material or different materials. The first polymer may be a highly liquid-absorbent polymer, and the second polymer may be a highly liquid-retaining polymer.

[0128] When the first polymer and the second polymer are selected from the same material, this material may simultaneously have the ability to absorb and retain liquid.

[0129] When the first polymer and the second polymer are selected from different materials, the liquid absorption capacity of the first polymer may be stronger than the liquid absorption capacity of the second polymer, and the liquid retention capacity of the second polymer may be stronger than the liquid retention capacity of the first polymer. Optionally, the first polymer may include at least one of an ether-based polymer and an ester-based polymer. Optionally, the second polymer may include at least one of a fluorinated polymer and an aldehyde-ketone-based polymer.

[0130] The first polymer and the second polymer may each independently be selected from at least one of a fluorinated polymer, an ether-based polymer, an ester-based polymer, and an aldehyde ketone polymer.

[0131] In some embodiments, the first polymer and the second polymer each independently comprise a fluorinated polymer, and the crystallinity of the fluorinated polymer as measured by differential scanning calorimetry is greater than or equal to X C1 and 0 <X C1 ≦30%, and the melting temperature of the fluorinated polymer is T m1 and its unit is °C, 0 <T m1 ≦140.

[0132] Crystallization is the process by which atoms, ions, or molecules in a material are arranged in a certain spatial order to form an order. The configuration of a polymer during crystallization is determined by two factors: intramolecular and intermolecular forces. The intermolecular forces affect the stacking density between molecular chains. Crystallinity X C1 is used to characterize the crystallinity of a material and can be measured by differential scanning calorimetry (DSC). Specifically, the test steps are as follows: a 0.5g to 0.8g sample is used, the sample is placed in a crucible, and the sample is subjected to a temperature increase and decrease treatment under a nitrogen gas atmosphere, and the material-specific T g1 20°C lower than the initial temperature and material-specific T m1 The temperature is raised to a cut-off temperature 20°C higher than the glass transition temperature T. g1 and melting temperature T m1 etc. will be determined.

[0133] As a result, the fluorinated polymer has low crystallinity and melting temperature, the molecular chain arrangement is sparse, the inter-chain forces are small, adjacent molecular chains are easily opened, and the intermolecular chain rotation realizes the movement of chain segments, forming a molecular chain structure with high flexibility. In addition, the fluorinated polymer and the electrolyte in the battery cell form a gel-like substance, which can improve the cycle performance of the battery cell.

[0134] Illustratively, the crystallinity X of the fluorinated polymer measured by differential scanning calorimetry C1may be 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of the above values.

[0135] Illustratively, the melting temperature of the fluorinated polymer may be 10°C, 20°C, 50°C, 70°C, 90°C, 100°C, 120°C, 140°C, or a range consisting of any two of the foregoing values.

[0136] In some embodiments, the glass transition temperature of the fluorinated polymer is T g1 The unit is °C, and -150≦T g1 ≦60.

[0137] The glass transition temperature (Tg) is the temperature at which a polymer chain segment transitions from frozen to mobile. The Tg has a certain effect on the flexibility of the polymer molecular chain. The lower the Tg, the better the flexibility of the polymer molecular chain at room temperature. The higher the Tg, the worse the flexibility of the molecular chain at room temperature. The Tg may be measured by differential scanning calorimetry (DSC). The lower the Tg of a polymer, the better the flexibility of the molecular chain segments, and the easier it is for adjacent molecular chains to open. For example, the Tg of a fluorinated polymer may be -150°C, -120°C, -100°C, -80°C, -60°C, -30°C, 0°C, 30°C, 60°C, or a range consisting of any two of the above values.

[0138] In some embodiments, the fluorinated polymer comprises a structural unit shown in formula (AI): JPEG2026501684000028.jpg28164

[0139] In formula (AI), R 11 , R 12 , R 13 and R 14 each independently comprises a hydrogen atom, a fluorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 11 , R 12 , R 13 and R 14At least one of the groups contains a fluorine atom.

[0140] In some embodiments, the fluorinated polymer comprises a structural unit shown in formula (AII): JPEG2026501684000029.jpg30162

[0141] In formula (AI) and formula (AII), R 11 , R 12 , R 13 and R 14 each independently comprises a hydrogen atom, a fluorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 11 , R 12 , R 13 and R 14 At least one of the groups contains a fluorine atom.

[0142] In some embodiments, the fluorinated polymer comprises a structural unit shown in formula (AII): JPEG2026501684000030.jpg31167

[0143] In formula (AIII), R 15 includes a single bond, a substituted or unsubstituted C1-C3 alkyl group.

[0144] When the above group is substituted, the substituent may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxyl group, an ester group, and a halogen atom. The above substituent is a high-pressure-resistant substituent, which is advantageous for stabilizing the polymer structure. The halogen atom may include a fluorine atom, a chlorine atom, a bromine atom, etc. Optionally, the halogen atom includes a fluorine atom.

[0145] In an embodiment of the present application, the polymer may be obtained by further copolymerizing the above structural group with a small amount of other types of structural group (e.g., structural units such as olefin-based structural units, ester-based monomers, nitrile-based monomers, and amide-based monomers).

[0146] In some embodiments, p is a positive integer selected from 1-3.

[0147] In some embodiments, the degree of polymerization n of the fluorinated polymer is a positive integer selected from 1,000 to 30,000.

[0148] In some embodiments, R 11 , R 12 , R 13 and R 14 each independently comprise a hydrogen atom, a fluorine atom, a bromine atom, a substituted or unsubstituted C1-C2 alkyl group, or a substituted or unsubstituted C1-C2 alkoxy group, and optionally R 11 , R 12 , R 13 and R 14 each independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0149] In some embodiments, the fluorinated polymer comprises at least one of the structural units shown in formula (AI-1) to (AI-11): JPEG2026501684000031.jpg113170

[0150] In some embodiments, the fluorinated polymer comprises at least one of the structural units shown in formula (AII-1) to formula (AII-5): JPEG2026501684000032.jpg73170

[0151] In some embodiments, the fluorinated polymer comprises at least one of the structural units shown in formula (AIII-1) to (AIII-3): JPEG2026501684000033.jpg60170

[0152] Illustratively, the fluorinated polymer includes one or more of polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, perfluoroethylene propylene copolymer FEP, perfluoroalkoxy polymer PFA, perfluoropolyether PFPE, polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP, polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE, and perfluoro(1-butenyl vinyl ether) polymer (abbreviated as CYTOP).

[0153] Optionally, the fluorinated polymer comprises one or more of polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, perfluoroethylene propylene copolymer FEP, polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP, polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE.

[0154] The fluorinated polymer may be derived from one or more of the following monomers: fluorocycloethane, vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene. Alternatively, the fluorinated polymer may be derived from at least two of the following monomers: fluorocycloethane, vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene.

[0155] The monomers used in the above fluorinated polymers are all short-chain monomers, which are advantageous for forming a linear or short-branched structure upon polymerization. Such structural types have a low degree of entanglement, which is advantageous for improving the flexibility of the molecular chains, and the molecular chains can be sufficiently extended in the electrolyte, which is advantageous for the polymer and the electrolyte to form a three-dimensional gel-state substance, which is advantageous for further improving the liquid absorption rate.

[0156] In some embodiments, the degree of polymerization n of the fluorinated polymer is a positive integer selected from 5,000 to 20,000.

[0157] In some embodiments, the molecular weight of the fluorinated polymer is 1.2×10 5 g / mol ~ 1.5 × 10 6 g / mol, and selectively 1.2 x 10 5 g / mol ~ 1.0 × 10 6g / mol. When the molecular weight of the polymer is within this range, the polymer exhibits a certain solubility in the electrolyte and is less likely to be completely dissolved or dispersed in the electrolyte, which is advantageous for controlling the distribution and dispersion of the polymer. It also improves the flexibility of the polymer's molecular chains, weakening the interchain interaction and allowing the solvent molecules in the electrolyte to open the molecular chains, enter between them, and be enveloped by them, which is advantageous for allowing active ions to enter the active material through the solvent, thereby achieving smooth and rapid migration of the active ions. When the molecular weight of the polymer is within this range, it is advantageous for improving the liquid absorption speed and liquid retention capacity of the separator.

[0158] Illustratively, the molecular weight of the polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.5 × 10 6 It may be g / mol or a range consisting of any two of the above values.

[0159] [Ether polymer]

[0160] In some embodiments, the first polymer and the second polymer each independently comprise an ether-based polymer, and the ether-based polymer is formed into a sheet-like structure and (T m2 A dynamic frequency scan test was performed at +20°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve was K1, and 1 <K1<∞であり、T m2 ° C. represents the melting temperature of the ether polymer.

[0161] Specifically, the process for producing the sheet-like structure is as follows: the ether-based polymer is vacuum-dried at 80°C for 12 hours. The dried ether-based polymer is hot-pressed into a sheet using a flat vulcanizer, and the hot-pressing temperature is (T m2The temperature is set to +20°C, the rolling thickness is 1-2 min, the rolling time is 2 min, and the pressure is 8 MPa. After 2 min of rolling, the sample is removed and placed in another vulcanizer of the same model for cold pressing, with the cold pressing pressure being 10 MPa. A circular mold with a diameter of 25 mm can be used to obtain polymer pellets (sheet-like structures) of a certain size. For example, the sheet-like structures may be pellets with a thickness of 1-2 mm and a diameter of 25 mm. Samples may be manufactured based on the sample standards required for the testing equipment.

[0162] Based on the conclusions of classical linear viscoelasticity, for polymers, especially linear polymers, the storage modulus G'-loss modulus G" curve in the terminal region (the range approaching the maximum value of the angular velocity) conforms to a frequency dependence, and the longest chain of the polymer affects the viscoelastic behavior.

[0163] The specific steps of the dynamic frequency sweep test are as follows: The dynamic frequency sweep test is performed using a TA-AR2000EX rotational rheometer (TA Instruments, USA). The parallel plates have a diameter of 25 mm and a thickness of 0.9 mm. To ensure that the test is performed in the linear viscoelastic region, the strain during the dynamic frequency sweep test is 2% and the test temperature is T m2 At +20°C, the test frequency scan range is 500rad / s≦w 2 ≦0.05 rad / s, thereby obtaining data in the lowest possible frequency range.

[0164] The dynamic frequency scanning test can characterize the degree of entanglement of molecular chains under solid-phase melting (molten state). Compared with linear structures or short-branched structures, long-branched structures, network structures, and low-crosslinked structures have a high degree of entanglement and show a behavior of deviating from the linear end. Ether-based polymers exhibit solid-phase behavior. When the ether-based polymer of the present application satisfies the above range, the entanglement state of the molecular chains can be further reduced, which is advantageous for the diffusion of solvent molecules between molecular chains in the electrolyte. Moreover, the ether-based polymer can still maintain a certain degree of entanglement of molecular chains and form a gel-like substance with the electrolyte, improving the cycle performance and storage performance of the battery cell.

[0165] In some embodiments, 1 < K1 ≤ 100, and optionally, 1 < K1 ≤ 10. Exemplarily, K1 may be 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above numerical values.

[0166] In some embodiments, the glass transition temperature of the ether-based polymer is T g2 where the unit is °C, -100 ≤ T g2 ≤ 50, and optionally, -80 ≤ T g2 ≤ 30. Exemplarily, the glass transition temperature of the ether-based polymer may be -100 °C, -80 °C, -60 °C, -30 °C, 0 °C, 30 °C, 50 °C, or a range consisting of any two of the above numerical values.

[0167] In some embodiments, the ether-based polymer includes a structural unit represented by formula (BI), JPEG2026501684000034.jpg33163

[0168] In formula (BI), R 21 and R 22 each independently include a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 23 includes a substituted or unsubstituted C1-C5 methylene group.

[0169] In some embodiments, R 21 and R 22 each independently comprises a hydrogen atom or a substituted or unsubstituted C1-C2 alkyl group.

[0170] In some embodiments, R 23 includes a single bond, a substituted or unsubstituted C1-C4 methylene group.

[0171] Illustratively, the ether-based polymer includes at least one of the structural units represented by formulas (BI-1) to (BI-8), JPEG2026501684000035.jpg101170

[0172] In some embodiments, the ether-based polymer comprises a structural unit shown in formula (BII): JPEG2026501684000036.jpg33166

[0173] In formula (BII), R 24 ~R 27 each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group; R 24 ~R 27 At least one of comprises a substituted or unsubstituted C1-C3 alkoxy or ether group.

[0174] In some embodiments, R 24 ~R 27 each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, a substituted or unsubstituted C1-C2 alkoxy group, or an ether group; R 24 ~R 27 At least one of comprises a substituted or unsubstituted C1-C2 alkoxy or ether group.

[0175] In some embodiments, the ether-based polymer comprises at least one of the structural units shown in formula (BII-1) to formula (BII-7), JPEG2026501684000037.jpg119170

[0176] The monomers used in the above ether polymers are multi-membered ring structures, such as six-membered rings or shorter chain monomers, which are advantageous for forming a high content of -O- structures upon polymerization. Such structural types have a low degree of entanglement, which is advantageous for improving the flexibility of the molecular chains, allowing the molecular chains to fully extend in the electrolyte and easily form a gel-state material with the electrolyte, thereby improving the cycle performance and storage performance of the battery cell.

[0177] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by further copolymerizing the above structural groups with other types of structural groups (e.g., structural units such as olefin-based structural units, ester-based monomers, nitrile-based monomers, and amide-based monomers).

[0178] When the above groups are substituted, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxyl group, an ester group, and a halogen atom. The above substituents are high-pressure-resistant substituents and are advantageous for stabilizing the polymer structure. The halogen atoms may include fluorine atoms, chlorine atoms, bromine atoms, etc.

[0179] In some embodiments, the degree of polymerization n of the ether-based polymer is a positive integer selected from 1,500 to 25,000.

[0180] Alternatively, the degree of polymerization n of the ether-based polymer is a positive integer selected from 3,000 to 18,000.

[0181] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 106 is g / mol.

[0182] Exemplarily, the molecular weight of the polymer is 1.2×10 5 g / mol, 2×10 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol or a range consisting of any two of the above numerical values may also be acceptable.

[0183] [Ester-based polymer]

[0184] In some embodiments, the first polymer and the second polymer each independently contain an ester-based polymer, the ester-based polymer is manufactured into a sheet-like structure, and a dynamic frequency scanning test is performed on the sheet-like structure at (T m3 +20)°C to obtain a storage modulus G’ - loss modulus G” curve. The slope of the storage modulus G’ - loss modulus G” curve is K2, and 1 < K2 < ∞. T m3 °C represents the melting temperature of the ester-based polymer.

[0185] When the ester-based polymer of the embodiment of the present application satisfies the above range, the entanglement state of the molecular chains can be further reduced, which is beneficial to the diffusion between the molecular chains of the solvent molecules in the electrolyte. Moreover, the ether-based polymer can still maintain a certain entanglement state of the molecular chains, form an electrolyte and a gel-like substance, and improve the cycle performance and storage performance of the battery cell by improving the liquid absorption rate.

[0186] In some embodiments, 1 < K2 ≤ 100, and optionally, 1 < K2 ≤ 10.

[0187] Exemplarily, K2 may be 1.01, 1.1, 1.2, 1.5, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000 or a range consisting of any two of the above numerical values.

[0188] In some embodiments, the glass transition temperature of the ester-based polymer is T g3 The unit is °C, and -100≦T g3 ≦50, and optionally, −80≦T g3 ≦30.

[0189] For example, the glass transition temperature of the ester-based polymer may be −100° C., −90° C., −80° C., −60° C., −30° C., 0° C., 30° C., 50° C., or a range consisting of any two of the above values.

[0190] In some embodiments, the ester-based polymer comprises a structural unit shown in formula (CI): JPEG2026501684000038.jpg45170

[0191] In formula (CI), R 31 , R 32 and R 33 each independently comprises a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group; R 34 comprises a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group, optionally R 34 includes a substituted or unsubstituted C1-C6 alkyl group, or a substituted or unsubstituted C1-C6 hydroxyalkyl group.

[0192] Selectively, R 31 contains a hydrogen atom or a substituted or unsubstituted methyl group.

[0193] Selectively, R 32 and R 33 each independently contains a hydrogen atom.

[0194] Selectively, R 34 includes a substituted or unsubstituted C1-C4 alkyl group, or a substituted or unsubstituted C1-C4 hydroxyalkyl group.

[0195] Illustratively, the ester-based polymer includes at least one of the structural units represented by formula (CI-1) to formula (CI-15), JPEG2026501684000039.jpg203170JPEG2026501684000040.jpg66170

[0196] In some embodiments, the ester-based polymer comprises a structural unit shown in formula (CII): JPEG2026501684000041.jpg22170

[0197] In formula (CII), R 35 contains a substituted or unsubstituted C2-C6 methylene group.

[0198] Selectively, R 35 each independently comprises a substituted or unsubstituted C2-C4 methylene group.

[0199] Illustratively, the ester-based polymer includes at least one of the structural units represented by formulas (CII-1) to (CII-5), JPEG2026501684000042.jpg61170

[0200] The above-mentioned ester-based polymer has a low degree of entanglement of the molecular chains, which is advantageous in improving the flexibility of the molecular chains, and the molecular chains can be sufficiently extended in the electrolyte solution, making it easy to form a gel-state substance with the electrolyte solution.

[0201] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by further copolymerizing the above structural groups with other types of structural groups (e.g., structural units such as olefin-based structural units, ester-based monomers, nitrile-based monomers, and amide-based monomers).

[0202] When the above groups are substituted, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxyl group, an ester group, and a halogen atom. The above substituents are high-pressure-resistant substituents and are advantageous for stabilizing the polymer structure. The halogen atoms may include fluorine atoms, chlorine atoms, bromine atoms, etc.

[0203] In some embodiments, the degree of polymerization n of the ester-based polymer is a positive integer selected from 800 to 20,000.

[0204] Alternatively, the degree of polymerization n of the ester polymer is a positive integer selected from 1,000 to 15,000.

[0205] In some embodiments, the molecular weight of the ester-based polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0206] Illustratively, the molecular weight of the ester polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.5 × 10 6 It may be g / mol or a range consisting of any two of the above values.

[0207] [Ketone aldehyde polymer]

[0208] In some embodiments, the first polymer and the second polymer each independently comprise an aldehyde ketone polymer, and the aldehyde ketone polymer is formed into a sheet-like structure, and (T m4 A dynamic frequency scan test is performed at +20°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve is K3, 0.8≦K3<∞, and T m4°C represents the melting temperature of the aldehyde ketone polymer.

[0209] In some embodiments, 0.8≦K3≦100, and optionally, 0.8≦K3≦10.

[0210] Illustratively, K3 may be 0.8, 0.9, 1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above values.

[0211] In some embodiments, the glass transition temperature of the aldehyde ketone polymer is T g4 The unit is °C, and -100≦T g4 ≦50, and optionally, −80≦T g4 ≦30.

[0212] Illustratively, the glass transition temperature of the aldehyde ketone polymer may be −100° C., −90° C., −80° C., −60° C., −30° C., 0° C., 30° C., 50° C., or a range consisting of any two of the above values.

[0213] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (DI): JPEG2026501684000043.jpg39170

[0214] In formula (DI), R 41 contains a single bond, a substituted or unsubstituted C1-C6 methylene group, and R 42 contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group,

[0215] Selectively, R 41 includes a single bond, a substituted or unsubstituted C1-C2 methylene group,

[0216] Selectively, R 42 includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group.

[0217] In the embodiments of the present application, a single bond represents the absence of a group, and the atoms on both sides of the group are connected by a single bond, such as R 41 is a single bond, and R 41 represents that the carbon atoms on both sides are connected by a single bond.

[0218] Illustratively, the aldehyde ketone polymer includes at least one of the structural units represented by formulas (DI-1) to (DI-6), JPEG2026501684000044.jpg113170

[0219] Illustratively, the aldehyde ketone polymer comprises a structural unit shown in formula (DII): JPEG2026501684000045.jpg29170

[0220] In formula (DII), R 43 ~R 46 each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from a positive integer; and optionally, R 43 ~R 46 each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C2 hydroxyalkyl group, or a substituted or unsubstituted C1-C2 alkoxy group.

[0221] In some embodiments, the aldehyde ketone polymer comprises at least one of the structural units shown in formula (DII-1) to (DII-4): JPEG2026501684000046.jpg80170

[0222] The aldehyde ketone polymer has a low degree of molecular chain entanglement, which is advantageous for improving the flexibility of the molecular chain. The molecular chain can be sufficiently extended in the electrolyte, which is advantageous for forming a gel-state substance with the electrolyte.

[0223] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by further copolymerizing the above structural groups with other types of structural groups (e.g., structural units such as olefin-based structural units, ester-based monomers, nitrile-based monomers, and amide-based monomers).

[0224] When the above groups are substituted, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxyl group, an ester group, and a halogen atom. The above substituents are high-pressure-resistant substituents and are advantageous for stabilizing the polymer structure. The halogen atoms may include fluorine atoms, chlorine atoms, bromine atoms, etc.

[0225] In some embodiments, the degree of polymerization n of the aldehyde ketone polymer is a positive integer selected from 500 to 15,000.

[0226] Optionally, the degree of polymerization n of the aldehyde ketone polymer is a positive integer selected from 500 to 10,000.

[0227] In some embodiments, the molecular weight of the aldehyde ketone polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0228] Illustratively, the molecular weight of the aldehyde ketone polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.0 × 10 6It may be g / mol or a range consisting of any two of the above values.

[0229] The relevant parameters of the polymers of the embodiments of the present application may be detected in the following manner:

[0230] The groups of the polymers of the embodiments of the present application may be detected by infrared spectroscopy IR, specifically, the liquid-holding polymer is tested by Thermo Nicolet Nexus 670 Attenuated Total Reflection Fourier Transform Infrared Spectrometer (FTIR-ATR), and the test is performed in accordance with the standard GB / T6040-2002, and the test range is ATR method 600-4000 cm -1 and the overlap is ±2cm -1 and the resolution is 4cm -1 The penetration depth is 0.2 to 0.6 μm.

[0231] The structure of the polymers of the present application may be examined by nuclear magnetic resonance NMR, specifically, H NMR and C NMR were performed on a Varian Mercury Plus-400 nuclear magnetic resonance spectrometer, the test temperature was 20° C., TMS was the internal standard, CDCl was the solvent, and the proton resonance frequency was 400 MHz.

[0232] The polymer monomer type of the polymer in the embodiment of the present application (particularly suitable for the monomers in the polymers with relatively low content) can be carried out by a combination of decomposition-gas chromatography-mass spectrometry. The specific test steps are as follows: 0.5 mg of sample is accurately weighed and injected into a sample cup, which is fixed to an injection rod and then placed in a decomposition furnace installed near the GC (gas chromatography) inlet. When the temperature of the decomposition furnace reaches the set temperature, the injection button is pressed, and the sample cup falls freely and quickly into the core of the decomposition furnace. In the inert gas N2 atmosphere, the volatile components are instantly vaporized and carried by the carrier gas into the gas chromatography column for separation. Finally, the sample is detected by a flame ionization detector FID or a mass spectrometer MS to obtain a gas chromatography or total ion chromatogram.

[0233] The molecular weight of the polymer in the embodiment of the present application is a well-known meaning in the art, and can be measured by instruments and methods commonly used in the art, and can be tested by gel permeation chromatography (GPC). The specific test steps are as follows: take an appropriate amount of sample to be measured (just ensure that the sample concentration is 8%-12% and the degree of opacity is 8%), add 20ml deionized water, and simultaneously perform external ultrasonic treatment (53KHz / 120W) for 5 minutes to ensure complete dispersion of the sample, and then measure the sample in accordance with GB / T19077-2016 / ISO 13320:2009 standard.

[0234] Alternatively, the test was performed using a multi-angle light scattering detector (MALLS). Specifically, a GPC system using a Dawn Heleos II multi-angle light scattering detector, an Optilab T-rEX refractive index (RI) detector, and a Visco Star II viscometer (Wyatt Technology Corporation, USA) was used. The test was performed at 30°C using tetrahydrofuran as the mobile phase at a flow rate of 1.0 ml / min. The SEC-SAMLL data was processed using the commercial software ASTRA6 to obtain molecular weight parameters.

[0235] In some embodiments, a polymer group is added to a first solvent at 70°C to form a polymer system, the polymer system is allowed to stand at 70°C for 8 hours, and then allowed to stand at 25°C for ≥ 24 hours. After that, the polymer system is filtered through a 200-mesh filter to leave a first substance, wherein the mass of the polymer group is q (g), the mass of the first substance is m (g), and the masses of the polymer group and the first substance satisfy 5 ≤ m / q ≤ 1000. In particular, the liquid-retaining polymer has a performance satisfying 5 ≤ m / q ≤ 1000.

[0236] The polymer group has excellent liquid absorption and retention properties, and is advantageous in improving the liquid absorption and retention capabilities of the separator.

[0237] In some embodiments, 10≦m / q≦1000, and more optionally, 10≦m / q≦50. Illustratively, m / q can be 5, 10, 20, 25, 28, 30, 32, 35, 40, 50, 80, 100, 200, 500, 1000, or a range consisting of any two of the foregoing values.

[0238] The polymer system is allowed to stand at 70°C for 8 hours and then at 25°C for at least 24 hours. After these two standing steps, a portion of the polymer system will swell and adsorb to transform into a gel-state substance. When the polymer comes into contact with the electrolyte, the polymer molecular chains will expand and open, allowing the electrolyte to diffuse between the molecular chains. The polymer molecular chains will swell and adsorb the electrolyte, which is beneficial to improving the liquid absorption and retention capabilities of the separator and further improving the cycle performance of the battery cell.

[0239] Illustratively, the ratio of the mass content of the polymer group to the mass content of the first solvent relative to the mass of the polymer system ranges from 1:100 to 1:10, for example, 3:50.

[0240] Exemplarily, the first solvent may be the same as or similar to the solvent of the electrolyte solution and may include at least one of a carbonate ester solvent and an ether solvent, for example, a carbonate ester solvent may include a cyclic carbonate ester solvent and / or a linear carbonate ester solvent.

[0241] Examples of cyclic carbonate ester solvents include one or more of ethylene carbonate EC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinylethylene carbonate VEC, and dicaprylyl carbonate CC.

[0242] Examples of linear carbonate ester solvents include one or more of dimethyl carbonate DMC, diethyl carbonate DEC, methyl ethyl carbonate EMC, diphenyl carbonate DPC, allyl methyl carbonate MAC, and polycarbonate VA.

[0243] Examples of the ether solvent include one or more of tetrahydrofuran THF, 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane DOL, dimethoxymethane DMM, 1,2-dimethoxyethane DME, and diethylene glycol dimethyl ether DG.

[0244] Optionally, the first solvent may also contain a lithium salt and an electrolyte additive, such as lithium hexafluorophosphate, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and the like.

[0245] In this application, m / q, also referred to as the sedimentation value, characterizes the ability of a polymer group and solvent to transform into a gel-state material.

[0246] The first substance mainly contains a gel-state substance formed by the polymer group and the first solvent, and in such a gel-state substance, the molecular structure of the polymer does not substantially change.

[0247] In some embodiments, the first substance is dried at 80°C for 12 hours to remove the first solvent in the first substance, and then subjected to infrared spectrophotometry (IR) or nuclear magnetic resonance (NMR) testing, and the main component of the first substance after drying is the liquid-retaining polymer described above.

[0248] In an embodiment of the present application, by increasing the temperature, the polymer molecular chains can be extended within the safe operating temperature range of the battery cell, promoting mutual attraction and physical bonding between the polymer molecular chains and the electrolyte. At room temperature, the activity of the polymer molecular chain segments is reduced, and they remain attached to the separator, locking the electrolyte in the spatial environment where the polymer groups are located, forming a gel or gel-like state, which can improve the transfer rate of active ions, such as lithium ions, and cycle performance.

[0249] In some embodiments, the separator comprises a porous substrate, and the polymer groups are distributed within the pores of the porous substrate.

[0250] In another embodiment, the separator includes a porous substrate and a polymer layer including polymer groups disposed on at least one surface of the porous substrate. The polymer layer disposed on at least one surface of the porous substrate means that the polymer layer may be disposed on one surface of the porous substrate or on both surfaces of the porous substrate. The polymer groups can be dispersed in a solvent to form a polymer mixture, which is then coated onto the porous substrate by a coating process such as atomized spray coating or gravure coating.

[0251] In the embodiment of the present application, the material of the porous substrate is not particularly limited, and any well-known porous substrate having good chemical and mechanical stability may be selected. For example, the porous substrate may include at least one of a porous polyolefin resin film (e.g., at least one of polyethylene, polypropylene, and polyvinylidene fluoride), a porous glass fiber, and a porous nonwoven fabric. The porous substrate may be a single-layer thin film or a multilayer composite film. When the porous substrate is a multilayer composite film, the materials of each layer may be the same or different.

[0252] In some embodiments, the porosity of the porous substrate is 25% or more, and optionally 25% to 50%. When the porosity of the porous substrate is in the above range, the air permeability of the porous substrate can be improved, which is favorable for the migration of active ions, and the small porosity can further improve the mechanical performance of the porous substrate, providing good support for the polymer layer.

[0253] In some embodiments, the thickness of the porous substrate may be 16 μm or less, optionally 5 μm to 12 μm. Illustratively, the thickness of the porous substrate may be 1 μm, 2 μm, 3 μm, 5 μm, 10 μm, 12 μm, 15 μm, 16 μm, or a range consisting of any two of the foregoing values.

[0254] Optionally, the polymer layer contains heat-resistant particles. The synergistic effect of the heat-resistant particles and the polymers can further improve the heat resistance and ion transport performance of the separator as a whole. The polymers and the heat-resistant particles can be dispersed in a solvent to form a polymer mixture, which is then coated onto the porous substrate by a coating process such as atomized spray coating or gravure coating.

[0255] In some embodiments, the ratio of the mass percentage of the polymer group to the mass percentage of the heat-resistant particles relative to the total mass of the polymer layer is (0.2 to 5.0): 1, and optionally (0.5 to 2.0): 1. When the contents of the heat-resistant particles and the polymer group are within the above ranges, the heat resistance and ion transport performance of the entire separator can be further improved. Illustratively, the ratio of the mass percentage of the polymer group to the mass percentage of the heat-resistant particles may be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.5:1, 1.8:1, 2.0:1, 2.5:1, 2.8:1, 3.0:1, 3.2:1, 3.5:1, 3.8:1, 4.0:1, 4.2:1, 4.5:1, 4.8:1, 5.0:1, or a range consisting of any two of the above values.

[0256] In some embodiments, the thickness of the polymer layer may be 0.5 μm to 3.0 μm, and optionally 1.0 μm to 2.0 μm. When the thickness of the polymer layer is within this range, the heat resistance and ion transport performance of the entire separator can be further improved. Illustratively, the thickness of the polymer layer may be 0.5 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2.0 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3.0 μm, or a range consisting of any two of the above values.

[0257] Optionally, the separator may further include a heat-resistant coating layer located on at least one surface of the porous substrate, with the polymer layer located on the side of the heat-resistant coating layer away from the porous substrate.

[0258] The heat-resistant coating layer may contain heat-resistant particles. In some embodiments, the heat-resistant particles include at least one of inorganic particles and organic particles. By adding heat-resistant particles, the heat-resistant performance of the separator can be improved.

[0259] In some embodiments, the mass percentage of the inorganic particles in the heat-resistant coating layer is ≤ 30. Exemplarily, the mass percentage of the inorganic particles in the heat-resistant coating layer is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30% or a range consisting of any two of the above numerical values.

[0260] The inorganic particles may include at least one of inorganic particles having a dielectric constant of 5 or more, inorganic particles having an active ion transport ability, and inorganic particles capable of electrochemical oxidation and reduction.

[0261] In some embodiments, the inorganic particles having a dielectric constant of 5 or more are boehmite (γ-AlOOH), alumina (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon oxide SiO x (0 < x ≤ 2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), nickel oxide (NiO), hafnium dioxide (HfO2), cerium oxide (CeO2), zirconium titanate (ZrTiO3), barium titanate (BaTiO3), magnesium fluoride (MgF2), Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1) and Pb(Mg3Nb 2 / 3 )O3-PbTiO3 (abbreviated as PMN-PT) may include at least one of them.

[0262] In some embodiments, the inorganic particles having active ion transport ability may include at least one of lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y -based glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), SiS2-based glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4) and P2S5-based glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7).

[0263] In some embodiments, the inorganic particles capable of electrochemical oxidation and reduction may include at least one of lithium-containing transition metal oxides, olivine-structured lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium titanium compounds.

[0264] In some embodiments, the heat-resistant coating layer may further include other organic particles, for example, the organic particles may include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenol aldehyde resin, polypropylene, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymers of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0265] In some embodiments, the heat-resistant coating layer may further include an adhesive, for example, at least one of a water-soluble acrylic acid-based resin (e.g., a homopolymer of acrylic acid, methacrylic acid, or sodium acrylate monomer or a copolymer with other copolymerizable monomers), polyvinyl alcohol (PVA), an isobutylene-maleic anhydride copolymer, and polyacrylamide.

[0266] In some embodiments, the thickness of the heat-resistant coating layer is ≦4 μm, which contributes to improving the energy density of the battery cell. In the embodiments of the present application, the thickness of the heat-resistant coating layer refers to the thickness of the heat-resistant coating layer located on one side of the substrate. Illustratively, the thickness of the heat-resistant coating layer may be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, or a range consisting of any two of the foregoing values.

[0267] In some embodiments, the coating basis weight of the polymers is 0.5 mg / 1540.25 mm 2 ~5mg / 1540.25mm 2 is.

[0268] When the coating basis weight is within the above range, the ability to form a gel-state substance with the electrolyte is further improved, thereby improving the liquid absorption rate.

[0269] Optionally, the coating basis weight of the polymer group is 0.5 mg / 1540.25 mm 2 ~3.5mg / 1540.25mm 2 is.

[0270] Exemplarily, the coating basis weight of the liquid-retaining polymer of the separator per unit area is 0.5 mg / 1540.25 mm 2 , 0.8mg / 1540.25mm 2 , 1.0mg / 1540.25mm 2 , 1.2mg / 1540.25mm 2 , 1.3mg / 1540.25mm 2 , 1.5mg / 1540.25mm 2 , 2.0mg / 1540.25mm 2 , 2.2mg / 1540.25mm 2 , 2.5mg / 1540.25mm 2 , 3mg / 1540.25mm 2 , 3.5mg / 1540.25mm 2 , 4mg / 1540.25mm 2 , 4.5mg / 1540.25mm 2 , 5mg / 1540.25mm 2 or a range consisting of any two of the above values.

[0271] In the embodiment of the present application, the coating basis weight is the coating basis weight of the liquid-retaining polymer on one side of the separator, which may be detected by equipment and methods well known in the art, for example, when the same master roll substrate and separator are applied to a 1540.25 mm 2 The weight of each of the 10 small separator pellets is measured and calculated, thereby obtaining the coating basis weight of the highly absorbent polymer on the separator.

[0272] Battery cell

[0273] According to a second aspect, an embodiment of the present application proposes a battery cell, the battery cell comprising an electrode component and an electrolyte, the electrode component comprising a positive electrode sheet, a negative electrode sheet and a separator, the separator being disposed between the positive electrode sheet and the negative electrode sheet and comprising a separator according to any of the embodiments of the first aspect of the present application.

[0274] [Positive electrode sheet]

[0275] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0276] For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode active material layer is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0277] The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be any positive electrode active material for battery cells well known in the art. For example, the positive electrode active material may include at least one of a lithium-containing phosphate compound, a lithium-containing transition metal oxide, a sodium-containing phosphate compound, and a sodium-containing transition metal oxide.

[0278] For example, the general formula of an olivine-type phosphate active material (lithium-containing phosphate compound) is Li x A y Me a M b P 1-c X c Y zwherein 0≦x≦1.3, 0≦y≦1.3, 0.9≦x+y≦1.3, 0.9≦a≦1.5, 0≦b≦0.5, 0.9≦a+b≦1.5, 0≦c≦0.5, 3≦z≦5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0279] Illustratively, the lithium transition metal oxide may be a layered material, such as a ternary system, lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium-rich layered material, and rock salt layered material. The general formula of the layered structure positive electrode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y z where 0≦x≦2.1, 0≦y≦2.1, 0.9≦x+y≦2.1, 0≦a≦1, 0≦b≦1, 0≦c≦1, 0.1≦a+b+c≦1, and 1.8≦z≦3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y includes one or more of O and F. Optionally, y=0. Specifically, the layered positive electrode active material may be lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), or LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 It may also contain one or more of O2 (NCM811) and NCA.

[0280] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. Examples of the metal foil sheet include aluminum foil or aluminum alloy foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include one or more combinations selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The polymer base layer may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0281] In some embodiments, the positive electrode active material layer further optionally contains a positive electrode conductive agent. In the embodiments of the present application, the type of positive electrode conductive agent is not particularly limited, and for example, the positive electrode conductive agent includes one or a combination of two or more selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, ketjen black, carbon spots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is 5% or less with respect to the total mass of the positive electrode active material layer.

[0282] In some embodiments, the positive electrode active material layer further optionally includes a positive electrode adhesive. In the embodiments of the present application, the type of positive electrode adhesive is not particularly limited. For example, the positive electrode adhesive may include one or a combination of materials selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In some embodiments, the mass percentage of the positive electrode adhesive is 5% or less with respect to the total mass of the positive electrode active material layer. The crystallinity of the positive electrode adhesive is higher than that of the fluorinated polymer of the embodiments of the present application. The melting temperature of the positive electrode adhesive is higher than that of the fluorinated polymer of the embodiments of the present application.

[0283] The positive electrode active material layer is typically formed by coating a positive electrode slurry onto 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). Of course, the manufacturing method of the positive electrode sheet is not limited to the above method, and the manufacturing method described above may also be used.

[0284] [Negative electrode sheet]

[0285] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer that includes a negative electrode active material and is disposed on at least one surface of the negative electrode current collector.

[0286] Exemplarily, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode active material layer is disposed on one or both of the two facing surfaces of the negative electrode current collector.

[0287] The negative electrode active material may be any negative electrode active material known in the art for battery cells. For example, the negative electrode active material may include at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. The silicon-based material may include, but is not limited to, at least one of elemental silicon, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy material. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0288] In some embodiments, the negative electrode active material layer optionally further includes a negative electrode conductive agent. In embodiments of the present application, the type of the negative electrode conductive agent is not particularly limited, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon powder, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent relative to the total mass of the negative electrode active material layer is ≦5%.

[0289] In some embodiments, the negative electrode active material layer optionally further includes a negative electrode adhesive. In embodiments of the present application, the type of the negative electrode adhesive is not particularly limited, and for example, the negative electrode adhesive may include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble acrylic acid-based resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode adhesive is ≦5% with respect to the total mass of the negative electrode active material layer.

[0290] In some embodiments, the negative electrode active material layer further optionally contains other additives. For example, the other additives may include a thickener, such as sodium carboxymethyl cellulose (CMC), a PTC thermistor material, etc. In some embodiments, the mass percentage of the other additives relative to the total mass of the negative electrode active material layer is ≦2%.

[0291] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. An example of a metal foil sheet is copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0292] The negative electrode active material layer is typically formed by coating a negative electrode slurry onto a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing a negative electrode active material, an optional conductive agent, an optional adhesive, and other optional additives in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water. Of course, the method for producing the negative electrode sheet is not limited to the above method, and the above-mentioned production methods may also be used.

[0293] The negative electrode sheet does not exclude additional functional layers other than the negative electrode active material layer. For example, in some embodiments, the negative electrode sheet described herein further includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) disposed on the surface of the negative electrode current collector and sandwiched between the negative electrode current collector and the negative electrode active material layer. In other embodiments, the negative electrode sheet described herein further includes a protective layer coated on the surface of the negative electrode active material layer.

[0294] [Electrolyte]

[0295] During the charge and discharge process of the battery cell, active ions are absorbed and released 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. In this application, the type of electrolyte is not particularly limited and can be selected according to actual needs.

[0296] The electrolyte solution includes an electrolyte salt and a solvent, and the types of the electrolyte salt and the solvent are not specifically limited and may be selected according to actual needs.

[0297] When the battery cell of the present application is a lithium-ion battery, for example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluoro(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), but is not limited thereto.

[0298] When the battery cell of the present application is a sodium-ion battery, for example, the electrolyte salt may include at least one of sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPOF), sodium difluoro(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP), but is not limited thereto.

[0299] For example, the solvent may be ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), diphenyl 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 ( The surfactants may include, but are not limited to, at least one of propylene glycol (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), tetrahydrofuran (THF), 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane (DOL), dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), and diethylene glycol dimethyl ether (DG).

[0300] In some embodiments, the electrolyte solution optionally further contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve some 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.

[0301] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet may be fabricated into an electrode component by a winding process and / or a lamination process.

[0302] In some embodiments, the battery cell may include an exterior packaging, which may be used to package the electrode components and electrolyte.

[0303] In some embodiments, the exterior of the battery cell may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the battery cell may be a soft bag, such as a pouch-type soft bag. The material of the soft bag may be at least one of plastic, such as polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0304] In some embodiments, the positive electrode sheet, separator, and negative electrode sheet may be fabricated into an electrode component by a winding or lamination process.

[0305] In the present application, the shape of the battery cell is not particularly limited, and may be cylindrical, rectangular, or any other shape. Figure 1 shows a battery cell 5 with a rectangular structure as an example.

[0306] In some embodiments, as shown in FIGS. 1 and 2 , the exterior may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate surround and form a storage chamber. The case 51 has an opening communicating with the storage chamber, and the cover plate 53 is used to cover the opening and close the storage chamber. The positive electrode sheet, the negative electrode sheet, and the separator may form an electrode component 52 through a winding process or a lamination process. The electrode component 52 is packaged in the storage chamber. An electrolyte is impregnated into the electrode component 52. The number of electrode components 52 included in the battery cell 5 may be one or more and can be adjusted according to needs.

[0307] The manufacturing method of the battery cell of the present application is well known. In some embodiments, a battery cell may 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 are wound or stacked to form an electrode component, which is then packaged in a housing, dried, and then injected with an electrolyte. The battery cell can then be obtained through processes such as vacuum packaging, standing, chemical conversion, and shaping.

[0308] In some embodiments of the present application, the battery cells according to the present application may be assembled into a battery module, and the number of battery cells included in the battery module may be plural, and the specific number can be adjusted according to the application and capacity of the battery module.

[0309] Fig. 3 is a schematic diagram of an example battery module 4. As shown in Fig. 3, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, any other layout method may also be used. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0310] Optionally, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

[0311] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted based on the application and capacity of the battery pack.

[0312] The battery module 4 and the battery pack may both be specific examples of the battery in the embodiments of the present application.

[0313] 4 and 5 are schematic diagrams of an example battery pack 1. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 is used to cover the lower housing 3 and form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be laid out in the battery box in any manner.

[0314] power consumption equipment

[0315] According to a third aspect, the present application provides a power consuming device, the power consuming device including at least one of the battery cell, battery module, and battery pack of the present application. The battery cell, battery module, and battery pack may function as a power source for the power consuming device, and may function as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobility device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0316] A power consuming device can be a battery cell, a battery module, or a battery pack depending on its usage needs. FIG. 6 is a schematic diagram of an example power consuming device. The power consuming device 6 may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density needs of the power consuming device, a battery pack 1 or a battery module may be adopted. Another example power consuming device may be a mobile phone, a tablet computer, a laptop computer, etc. These power consuming devices are generally required to be thin and lightweight, and may use battery cells as a power source.

[0317] Example

[0318] Examples of the present application are described below. The examples described below are illustrative and are intended only to interpret the present application and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out in accordance with the techniques or conditions described in literature in the field or in accordance with the product specifications. Reagents or equipment used without a specified manufacturer are all common products that can be purchased commercially.

[0319] Example 1: Manufacture of a lithium-ion battery

[0320] (1) Manufacturing of positive electrode sheet:

[0321] A 12 μm thick aluminum foil was used as the positive electrode current collector.

[0322] The positive electrode slurry was prepared by thoroughly mixing the positive electrode active material LiNi0.6Co0.2Mn0.2O2 (NCM622), conductive carbon black, and adhesive polyvinylidene fluoride (PVDF) in an appropriate amount of N-methylpyrrolidone (NMP). The mass ratio of NCM622, conductive carbon black, and PVDF in the positive electrode slurry was 97.5:1.4:1.1. The positive electrode slurry was coated onto an aluminum foil current collector, vacuum dried at 100°C, cold pressed, trimmed, sliced, and slit, and then vacuum dried at 85°C for 4 hours to produce a positive electrode sheet.

[0323] (2) Manufacturing of negative electrode sheet:

[0324] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0325] The negative electrode active material, artificial graphite, conductive agent, carbon black, adhesive, styrene butadiene rubber (SBR), and thickener, sodium hydroxymethylcellulose (CMC), were uniformly mixed in a weight ratio of 97.4:2:0.5:0.1 and then added to deionized water to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil current collector, dried at 85°C, and then cold-pressed, trimmed, sliced, and slit. The negative electrode sheet was then dried at 120°C under vacuum for 12 hours.

[0326] (3) Electrolyte production:

[0327] In an environment where the water content was less than 10 ppm, the non-aqueous organic solvents ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1 to obtain an electrolyte solvent, which was then mixed with lithium salt LiPF6 to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0328] (4) Separator manufacturing

[0329] A 7 μm polyethylene film (PE) was used as the substrate.

[0330] The polymer groups were dispersed in dimethyl carbonate (DMC) solvent to form a mixed system, which was then atomized and spray-coated onto both surfaces of a polyethylene film to form polymer layers. Water was used as the atomization solvent, and the mass content of the mixed system was 1%.

[0331] (5) Lithium-ion battery manufacturing:

[0332] The positive electrode sheet, separator and negative electrode sheet are stacked in this order, with the separator placed between the positive electrode sheet and the negative electrode sheet to provide a barrier, and then rolled up to obtain an electrode component. The electrode component is placed in an outer case, dried, and then an electrolyte is injected. After vacuum packaging, standing, chemical conversion and shaping, a lithium ion battery is obtained.

[0333] Comparative Example 1

[0334] A lithium ion battery was produced in the same manner as in Example 1, but was different from Example 1 in that the separator in Comparative Example 1 was a polyethylene film (PE) of 7 μm.

[0335] Comparative Examples 2 and 3

[0336] Lithium ion batteries were produced in the same manner as in Example 1, but were different from Example 1 in that the polymer group materials of the separators in Comparative Examples 2 and 3 were changed.

[0337] Examples 1-2 to 1-6

[0338] Lithium ion batteries were produced in the same manner as in Example 1, but differed from Example 1 in that the coating basis weight of the polymer group was adjusted in the polymer layer of the separator in Examples 1-2 to 1-6.

[0339] Examples 2-1 to 2-3

[0340] Lithium ion batteries were produced in the same manner as in Example 1, but differed from Example 1 in that the types of polymer groups in the polymer layers of the separators of Examples 2-1 to 2-3 were adjusted.

[0341] Example 3-1

[0342] A lithium ion battery was manufactured in the same manner as in Example 1, but differed from Example 1 in that the position of the polymer layer of the separator was adjusted in Example 3-1. Specifically, the separator manufacturing steps were as follows:

[0343] A 7 μm polyethylene film (PE) is used as the separator substrate,

[0344] A coating slurry is obtained by uniformly mixing silicon oxide particles and an aqueous polyacrylic acid adhesive in a mass ratio of 20:80 in an appropriate amount of deionized water.

[0345] Coating the prepared coating slurry on both surfaces of the PE substrate using a coating machine to form a heat-resistant coating layer;

[0346] The method includes dispersing the polymer group and the adhesive in a dimethyl carbonate (DMC) solvent to form a mixed system, atomizing the mixed system, and spray-coating the mixed system on the surface of the heat-resistant coating layer to form a polymer layer, thereby obtaining a separator.

[0347] Examples 3-2 to 3-5

[0348] Lithium ion batteries were manufactured in the same manner as in Example 1, but were different from Example 1 in that the separator manufacturing method was adjusted in Examples 3-2 to 3-5. Specifically, the separator manufacturing steps were as follows:

[0349] A 7 μm polyethylene film (PE) is used as the separator substrate,

[0350] A polymer group, silicon oxide particles, and an aqueous polyacrylic acid adhesive are mixed uniformly in a mass ratio of 80:20 in an appropriate amount of deionized water to obtain a coating slurry;

[0351] Coating the prepared coating slurry on both surfaces of the PE substrate using a coating machine to form a heat-resistant coating layer;

[0352] The method includes dispersing the polymer group and the adhesive in a dimethyl carbonate (DMC) solvent to form a mixed system, atomizing the mixed system, and spray-coating the mixed system on the surface of the heat-resistant coating layer to form a polymer layer, thereby obtaining a separator.

[0353] In Example 3-2, the mass ratio of the polymer group to the silicon oxide particles is 1.5:1.

[0354] In Example 3-3, the mass ratio of the polymer group to the silicon oxide particles is 0.5:1.

[0355] In Example 3-4, the mass ratio of the polymer group to the silicon oxide particles is 2:1.

[0356] In Examples 3-5, the weight ratio of polymer groups to silicon oxide particles is 0.2:1.

[0357] In Examples 3-5, the weight ratio of polymer groups to silicon oxide particles is 0.5:1.

[0358] The data for the examples and comparative examples are shown in Table 1.

[0359] Testing section

[0360] 1. Lithium-ion battery performance (cycle test under large fixture force)

[0361] Before the battery cycling, a preload of 10,000 N was applied to the battery core, and the lithium-ion battery was charged to 4.25 V at a constant current of 1 C at 25°C, then charged to a current of 1 C at a constant voltage of 4.25 V, and then discharged to 2.8 V at a constant current of 1 C. This constitutes one charge-discharge cycle. The capacity retention of the battery after 1,000 cycles was calculated by setting the capacity of the first discharge as 100%. The capacity retention of the battery after 1,000 cycles (%) = discharge capacity at the 1,000th cycle / capacity of the first discharge × 100%.

[0362] 2. Separator parameter testing

[0363] Test of separator mass M: Ten separators with an area of ​​1540.25 mm2 were cut using a cutting machine, and the weights were measured on an electronic balance. The weight of the separator at this time was designated as M.

[0364] m1 test: Ten cut separators with an area of ​​1540.25 mm2 were placed in 10 mL of 1M LiPF6 containing EC, EMC, and DMC electrolytes in a volume ratio of 1:1:1 for 2 hours, then removed and suspended for 2 minutes. The weight was then measured on an electronic balance and recorded as m1.

[0365] The retention rate was calculated as (m1-M) / M × 100%.

[0366] Test of m2: After immersion in the electrolyte, the separator was placed in a pressure device, pressurized to 10,000 N, and held for 5 minutes. The weight was measured on an electronic balance and recorded as m2.

[0367] The liquid retention rate after pressurization was calculated as (m2-M) / M × 100%.

[0368] The liquid holding capacity Λ is = (m2-M) / (m1-M) × 100%.

[0369] Test results

[0370] The test results are shown in Tables 1 and 2.

[0371] [Table 1]

[0372] In Table 1, 75% VDF means that the molar percentage of vinylidene fluoride VDF is 75% relative to the total molar amount of vinylidene fluoride VDF, hexafluoropropylene HFP, and ethylene.

[0373] [Table 2]

[0374] In Table 2, the liquid holding capacity Λ = [(m_2-M) / (m_1-M)].

[0375] The liquid retention rate (before pressure application) is (m1-M) / M x 100%.

[0376] The liquid retention rate (after pressure application) is (m2-M) / M x 100%.

[0377] Compared with Comparative Example 1, in the Examples of the present application, the cycle performance of the lithium ion battery was improved by adding the polymer of the present application to the separator.

[0378] In Comparative Examples 2 and 3, a polymer was added to the separator, but the polymer had poor liquid retention and absorption capabilities, and the cycle performance of the lithium ion battery could not be effectively improved.

[0379] Compared to Comparative Example 1, in the examples of the present application, a polymer layer is disposed on the surface of the separator. The introduction of the polymer can improve the separator's liquid absorption rate and liquid retention capacity, thereby further improving the cycle performance of the battery cell. While the present application has been described in connection with preferred embodiments, various modifications may be made and parts may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural contradiction, the technical features mentioned in each embodiment may be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions encompassed by the claims.

Claims

1. A separator comprising a group of polymers including at least one of a first polymer and a second polymer, The separator is Fulfilling M represents the mass of the separator without adsorbing the electrolyte, and its unit is g, m １ represents the mass of the separator weighed under ambient pressure after it has been immersed in the electrolyte for 2 hours, and its unit is g; m ２ represents the mass of the separator weighed under 10,000 N pressure at ambient pressure after the separator has been immersed in the electrolyte for 2 hours, and its unit is g; v represents the liquid absorption rate of the separator, and its unit is mg / s; λ represents the porosity of the separator.

2. The separator is The separator according to claim 1 , wherein

3. The separator is and selectively, The separator according to claim 1 or 2,

4. The separator is The separator according to any one of claims 1 to 3, which satisfies the following:

5. The separator is The separator according to any one of claims 1 to 4, which satisfies the following:

6. The separator is The separator according to any one of claims 1 to 5, which satisfies v / λ>5.00, and optionally satisfies 5<v / λ<50.

7. The separator according to any one of claims 1 to 6, wherein the mass percentage of the polymer group is 0.1% to 20% relative to the total mass of the separator.

8. the first polymer and the second polymer each independently comprise a fluorinated polymer; Optionally, the crystallinity of the fluorinated polymer as measured by differential scanning calorimetry is １ and 0<Xc １ ≦30%; The melting temperature of the fluorinated polymer is T ｍ１ and the unit is ° C., and 0<T ｍ１ ≦140, More preferably, the glass transition temperature of the fluorinated polymer is T ｇ１ and the unit is °C, and -150≦T ｇ１ ≦60, Further optionally, the fluorinated polymer comprises at least one of structural units represented by formula (AI) to (AIII), In formula (AI) and formula (AII), R １１ , R １２ , R １３ and R １４ each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R １１ , R １２ , R １３ and R １４ at least one of which contains a fluorine atom; In formula (AIII), R １５ comprises a single bond or a substituted or unsubstituted C1-C3 alkyl group, p is a positive integer selected from 1 to 3, and n is a positive integer selected from 1,000 to 30,000.

9. the first polymer and the second polymer each independently comprise an ether-based polymer; Optionally, the ether-based polymer is formed into a sheet-like structure, and the sheet-like structure is subjected to (T ｍ２ A dynamic frequency sweep test was performed at 20°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve was １ and 1<K １ <∞, and T ｍ２ ° C. represents the melting temperature of the ether-based polymer, Further optionally, the ether-based polymer comprises at least one of a structural unit represented by formula (BI) and a structural unit represented by formula (BII), In formula (BI), R ２１ and R ２２ each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R ２３ comprises a substituted or unsubstituted C1-C5 alkylene group; In formula (BII), R ２４ ~R ２７ each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group; R ２４ ~R ２７ The separator according to any one of claims 1 to 8, wherein at least one of comprises a substituted or unsubstituted C1-C3 alkoxy group or ether group.

10. the first polymer and the second polymer each independently comprise the ester-based polymer; Optionally, the ester-based polymer is formed into a sheet-like structure, and the sheet-like structure is subjected to (T ｍ３ A dynamic frequency sweep test was performed at 20°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve was ２ and 1<K ２ <∞, and T ｍ３ °C represents the melting temperature of the ester-based polymer, optionally 1 < K ２ ≦100, and further optionally, 1<K ２ ≦10, Further alternatively, the ester-based polymer comprises at least one of a structural unit represented by formula (CI) and a structural unit represented by formula (CII), In formula (CI), R ３１ , R ３２ and R ３３ each independently comprises a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group; R ３４ comprises a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group; In formula (CII), R ３５ comprises a substituted or unsubstituted C2-C6 methylene group, optionally R ３５ The separator according to any one of claims 1 to 9, wherein each independently comprises a substituted or unsubstituted C2-C4 methylene group.

11. the first polymer and the second polymer each independently comprise an aldehyde ketone polymer; Optionally, the aldehyde ketone polymer is formed into a sheet-like structure, and the sheet-like structure is subjected to (T ｍ４ A dynamic frequency sweep test was performed at 20°C to obtain a storage modulus G'-loss modulus G" curve, and the slope of the storage modulus G'-loss modulus G" curve was ３ and 0.8≦K ３ <∞, and T ｍ４ °C represents the melting temperature of the aldehyde ketone polymer, optionally 0.8 < K ３ ≦100, and more optionally, 0.8≦K ３ ≦10, Further alternatively, the aldehyde ketone polymer comprises at least one of a structural unit shown in formula (DI) and a structural unit shown in formula (DII), In formula (DI), R ４１ contains a single bond, a substituted or unsubstituted C1-C6 methylene group, and R ４２ contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group, In formula (DII), R ４３ ~R ４６ each independently comprise a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from positive integers.

12. The separator according to any one of claims 1 to 11, comprising a porous substrate and a polymer layer containing the polymers disposed on at least one surface of the porous substrate.

13. The coating basis weight of the polymer group is 0.5 mg / 1540.25 mm ２ ~5mg / 1540.25mm ２ The separator according to any one of claims 1 to 12,

14. A battery cell comprising the separator according to any one of claims 1 to 13.

15. A battery comprising the battery cell of claim 14.

16. 16. A power consuming device comprising the battery of claim 15.

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