Separators, battery cells, batteries, and power consumption devices

Abstract

This application provides a separator, a battery cell, a battery, and a power consumption device. The separator comprises a separator body and a polymer layer installed on at least one surface of the separator body, wherein the separator satisfies ν / λ > 5.00, where λ represents the porosity of the separator and v represents the liquid absorption rate of the separator, with units of mg / s.

Description

[Technical Field]

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

[0002] Battery cells have characteristics such as high capacity and long service life, and are therefore widely used in electronic devices such as mobile phones, laptops, battery cars, electric vehicles, electric airplanes, electric ships, electric vehicle toys, electric ship toys, electric airplane toys, and power tools.

[0003] As the range of battery applications expands, the requirements for battery cell performance are becoming increasingly stringent. However, the current cycle performance and storage performance of battery cells are low and need further improvement. [Overview of the project]

[0004] The embodiments of this invention have been made in view of the above-mentioned problems, and aim to provide a separator, a battery cell, a battery, and a power consumption device.

[0005] A first aspect of the present application provides a separator comprising a separator body and a polymer layer provided on at least one surface of the separator body, wherein the polymer layer comprises a liquid-absorbing polymer, the separator satisfies ν / λ > 5.00, where λ represents the porosity of the separator and v represents the liquid absorption rate of the separator, with units of mg / s.

[0006] As a result, the separator according to the embodiment of the present application includes a polymer layer, the polymer layer includes a liquid-absorbent polymer, ν / λ>5.00, the polymer layer is in contact with the electrolyte, the polymer molecular chains extend and open, and the electrolyte can diffuse between the molecular chains. The introduction of the liquid-absorbent polymer accelerates the absorption of the electrolyte, increases the suck-back speed of the electrolyte in the discharge process of the battery cell, speeds up the transport speed of the electrolyte between the separator and the electrode sheet, reduces the electrolyte shortage in the cycle charge-discharge process, reduces the polarization of the battery, and can improve the cycle performance of the battery cell. The introduction of the liquid-absorbent polymer can also form a uniform high wetting point between the separator and the electrode sheet, and uniformly improve the wetting performance of the separator and the electrode sheet. In addition, the liquid-absorbent polymer constructs a three-dimensionally communicating interface between the separator and the electrode sheet, further increasing the liquid absorption speed of the separator and the electrode sheet, thereby improving the cycle performance of the battery cell.

[0007] In some embodiments, the separator satisfies 5 < v / λ < 50.

[0008] In some embodiments, the range of the contact angle between the polymer layer and the electrolyte is 5° to 25°, the electrolyte includes lithium hexafluorophosphate and an organic solvent, the molar concentration of the lithium hexafluorophosphate is 1 mol / L, and the organic solvent includes ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate with a volume ratio of 1:1:1.

[0009] As a result, the polymer layer according to the embodiment of the present application has a liquid-absorbent polymer. Since the affinity between the liquid-absorbent polymer and the electrolyte is relatively good, the wetting performance of the separator and the electrolyte can be improved, thereby further increasing the liquid absorption speed of the separator, accelerating the absorption of the electrolyte, speeding up the transport speed of the electrolyte between the separator and the magnetoelectrode sheet, reducing the electrolyte shortage in the cycle charge process, and being advantageous for reducing the polarization of the battery. Thereby, the cycle performance of the battery cell is improved.

[0010] In some embodiments, the coating basis weight of the liquid absorbent polymer per unit area of the separator is 0.5 mg / 1540.25 mm 2 ~5 mg / 1540.25 mm 2 . When the coating basis weight is within the above range, the ability to form an electrolyte solution and a gel substance can be further improved, thereby increasing the liquid absorption rate.

[0011] In some embodiments, the liquid absorbent polymer includes a fluorinated polymer. The crystallinity of the fluorinated polymer measured by differential scanning calorimetry is Xc1, where 0 < Xc1 ≤ 30%. The melting temperature of the fluorinated polymer is T m1 , with the unit of °C, and 0 < T m1 ≤ 140.

[0012] In some embodiments, the glass transition temperature of the fluorinated polymer is T g1 , with the unit of °C, and -150 ≤ T g1 ≤ 60.

[0013] In some embodiments, the fluorinated polymer includes at least one of the structural units represented by formula (AI) to formula (AIII).

Chemical formula

[0014] 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 chlorine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group. At least one of R 11 , R 12 , R 13 and R 14 includes a fluorine atom.

Chemical formula

[0015] In formula (AIII),

[0016] R 15 includes a single bond, a substituted or unsubstituted C1-C3 alkyl group,

[0017] p is selected from positive integers of 1 to 3, and n is selected from positive integers of 1000 to 30000.

[0018] m2 In some embodiments, the liquid absorbent polymer further includes 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. The slope of the storage modulus G'-loss modulus G'' curve is K1, where 1 < K1 < ∞, and T

[0019] In some embodiments, the ether-based polymer includes a structural unit represented by formula (BI) to a structural unit represented by formula (BII),

Chemical formula

[0020] 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 alkylene group,

Chemical formula

[0021] In formula (BII), R 24 ~R​27 is each independently a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group or an ether group, and R 24 ~R 27 at least one of them contains a substituted or unsubstituted C1-C3 alkoxy group or an ether group.

[0022] In some embodiments, the liquid absorbent polymer contains an ester polymer, the ester polymer is made 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, 1<K2<∞, T m3 °C represents the melting temperature of the ester polymer, optionally, 1<K2≤100, and further optionally, 1<K2≤10.

[0023] In some embodiments, the ester polymer contains a structural unit represented by formula (CI) and / or a structural unit represented by formula (CII),

Chemical formula

[0024] In formula (CI), R 31 , R 32 and R 33 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C8 alkyl group, and R 34 contains a substituted or unsubstituted C1-C8 alkoxy group, or a substituted or unsubstituted C1-C8 hydroxyalkyl group,

Chemical formula

[0025] In formula (CII), R 35 contains a substituted or unsubstituted C2-C6 methylene group, and optionally, R 35 each independently contains a substituted or unsubstituted C2-C4 methylene group.

[0026] In some embodiments, the liquid absorbent polymer comprises an aldehyde-ketone polymer, the aldehyde-ketone polymer is fabricated into a sheet-like structure, and the sheet-like structure is subjected to (T m4 A dynamic frequency scanning test was performed at +20°C to obtain the storage modulus G'-loss modulus G'' curve, and the slope of the storage modulus G'-loss modulus G'' curve was K3, where 0.8 ≤ K3 < ∞, T m4 °C represents the melting temperature of the aldehyde-ketone polymer, selectively between 0.8 ≤ K3 ≤ 100, and further selectively between 0.8 ≤ K3 ≤ 10.

[0027] In some embodiments, the aldehyde-ketone polymer comprises a structural unit represented by formula (DI) and / or a structural unit represented by formula (DII), [ka]

[0028] In equation (DI), R 41 It contains single bonds, substituted or unsubstituted C1-C6 methylene groups, R 42 It contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group, [ka]

[0029] In equation (DII), R 43 ~R 46 Each of these independently comprises a hydrogen atom, a hydroxyl 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, where r and s are each independently selected from integers between 0 and 5, and at least one of r and s is selected from positive integers.

[0030] In some embodiments, the molecular weight of the liquid absorbent polymer is 1.2 × 10⁻⁶. 5 g / mol ~ 1.0 × 10 6It is g / mol.

[0031] In some embodiments, the separator body includes a substrate, and the polymer layer is installed on at least one surface of the substrate.

[0032] In some embodiments, the separator body includes a substrate and a heat-resistant coating layer, the heat-resistant coating layer being installed on at least one surface of the substrate, and the polymer layer being installed on a surface of the heat-resistant coating layer away from the substrate.

[0033] In some embodiments, the polymer layer further includes heat-resistant particles. The synergistic effect of the heat-resistant particles and the fluorinated polymer can further improve the overall heat resistance and ion transport performance of the separator.

[0034] In some embodiments, based on the total mass of the polymer layer, the ratio of the mass percentage of the fluorinated polymer to the mass percentage of the heat-resistant particles is (0.2-5):1, and selectively (0.5-2):1. When the content of heat-resistant particles and fluorinated polymer is within the above range, the overall heat resistance and ion transport performance of the separator can be further improved.

[0035] In some embodiments, the thickness of the polymer layer is 0.5 μm to 3.5 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.

[0036] In a second aspect, the present application provides a battery cell comprising a separator described in any embodiment of the first aspect of the present application.

[0037] In a third aspect, the present application provides a battery comprising a battery cell described in any embodiment of the second aspect of the present application.

[0038] In a fourth aspect, the present application provides a power consumption device which includes a battery as described in any embodiment of the third aspect of the present application. [Brief explanation of the drawing]

[0039] To more clearly explain the technical solutions of the embodiments of this application, the following is a brief introduction of the drawings necessary for the embodiments of this application. However, it is clear that the drawings in the following description represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these without requiring any creative effort.

[0040] [Figure 1] This is a schematic diagram of one embodiment of the battery cell of the present invention.

[0041] [Figure 2] Figure 1 is a schematic exploded view of an embodiment of the battery cell. [Figure 3] This is a schematic diagram of one embodiment of the battery module of the present invention. [Figure 4] This is a schematic diagram of one embodiment of the battery pack of the present invention. [Figure 5] Figure 4 is a schematic exploded view of an embodiment of the battery pack shown. [Figure 6] This is a schematic diagram of one embodiment of a power consumption device equipped with the battery cell of the present invention as a power source.

[0042] The drawings are not always drawn to the actual scale.

[0043] Explanation of symbols:

[0044] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module,

[0045] 5: Battery cell, 51: Case, 52: Electrode assembly,

[0046] 53: Cover plate,

[0047] 6, power consumption equipment. [Modes for carrying out the invention]

[0048] The following detailed description specifically discloses embodiments of the separator, battery cell, battery, and power consumption device of the present application. However, unnecessary details may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions of the same structure may be omitted. This is to avoid the following description becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0049] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of the present application can be combined to form new technical solutions.

[0051] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, that a method includes steps (a) and (b) indicates that a method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, that a method referred to above may further include step (c) indicates that step (c) may be added to the method in any order, for example, that a method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), and so on.

[0052] Unless otherwise specified, the terms “include” and “inclusive” as used in this application may be open-ended or closed-ended. For example, “include” and “inclusive” may include or include other components not listed, or they may include or include only the components listed.

[0053] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies the "A or B" condition: 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).

[0054] In this application, the terms "multiple" and "multiple types" mean two types or two or more types.

[0055] The term "alkyl group" includes both linear and branched alkyl groups. For example, alkyl groups may be C1-C5 alkyl groups, C1-C4 alkyl groups, C1-C3 alkyl groups, or C1-C2 alkyl groups. In some examples, alkyl groups include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, and the like. Alkyl groups may also be optionally substituted. If substituted, the substituents include fluorine atoms.

[0056] The term "alkoxy group" refers to a group in which an alkyl group is bonded to an oxygen atom by a single bond. For example, the alkoxy group may be a C1-C5 alkoxy group, a C1-C3 alkoxy group, or a C1-C2 alkoxy group. In some examples, the alkoxy group may include a methoxy group, an ethoxy group, and a propoxy group. Furthermore, the alkoxy group may be optionally substituted.

[0057] The term "halogen atom" refers to atoms such as fluorine, chlorine, and bromine.

[0058] The term "hydrogen" refers to 1H (practic hydrogen, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may also refer to 1H (practic hydrogen, H).

[0059] A battery cell comprises a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. The separator is located between the positive and negative electrode sheets, separating them. During the charge-discharge cycle process of the battery cell, the volume of the electrode assembly expands, and especially in the later stages of the cell cycle, the expansion force is large, causing the electrolyte to be squeezed out. The separator's liquid absorption rate is slow, making electrolyte suck-back difficult, increasing the risk of electrolyte depletion and bridge rupture in the electrode sheets. As a result, the cycle performance of the battery cell may decrease, potentially shortening the battery cell's cycle life.

[0060] In view of the above problems, an embodiment of the present invention provides a separator comprising a polymer layer comprising a liquid-absorbing polymer with ν / λ > 5.00, wherein the polymer layer is in contact with the electrolyte, the polymer molecular chains extend and open, and the electrolyte can diffuse between the molecular chains. The introduction of the liquid-absorbing polymer accelerates the absorption of the electrolyte, increases the electrolyte suck-back rate in the discharge process of the battery cell, speeds up the transport rate of the electrolyte between the separator and the electrode sheet, reduces electrolyte shortage in the cycle charge-discharge process, reduces battery polarization, and improves the cycle performance of the battery cell. The introduction of the liquid-absorbing polymer also forms a uniform high-wetting point between the separator and the electrode sheet, uniformly improving the wetting performance of the separator and the electrode sheet. Furthermore, the liquid-absorbing polymer constructs a three-dimensionally communicating interface between the separator and the electrode sheet, further increasing the liquid absorption rate between the separator and the electrode sheet, thereby improving the cycle performance of the battery cell.

[0061] Separator

[0062] In a first aspect, an embodiment of the present application provides a separator comprising a separator body and a polymer layer provided on at least one surface of the separator body, wherein the polymer layer comprises a liquid-absorbing polymer, the separator satisfies ν / λ > 5.00, where λ represents the porosity of the separator and v represents the liquid absorption rate of the separator, with units of mg / s.

[0063] The separator may be made of a substrate and a liquid-absorbing polymer, etc. Alternatively, the separator may be derived from a battery cell, the battery cell may be disassembled, the separator immersed in the electrolyte inside the battery cell may be removed, the separator may be washed with deionized water, and the separator may be vacuum-dried at 80°C for 12 hours to obtain the separator, which may then be used for separator tests such as liquid absorption rate.

[0064] In embodiments of the present application, the porosity of the separator is the ratio of the pore volume in the separator to the total volume of the separator, and can be detected using instruments and methods known in the art, for example, by GB / T21650.2-2008 "Measuring 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 method" and ASTMD2873-94el "Standard Test Method for Interior Porosity of Poly(Vinyl Choride) (PVC) Resins by Mercury Intrusion Porosimetry".

[0065] In the embodiments of this application, v represents the liquid absorption rate of the separator and can be detected using the following method, the specific steps being as follows:

[0066] Absorb 1 mL of electrolyte solution with a pipette,

[0067] Separator 1540.25mm 2 Cut it into small discs and place them horizontally in the air.

[0068] A 1 mL electrolyte solution is pipetteed and dropped onto the center of a small disc. Timing is started, and the time when the wetting radius of the electrolyte solution reaches 10 mm is recorded.

[0069] The ratio of the wetting radius to the wetting time is calculated to obtain the liquid absorption rate v.

[0070] This application tests a standard electrolyte as a test sample, and for specific electrolyte formulations, refer to the electrolyte formulations in the examples.

[0071] The separator of the embodiment of the present invention includes a polymer layer, the polymer layer includes a liquid-absorbing polymer with ν / λ > 5.00, the polymer layer is in contact with the electrolyte, the polymer molecular chains extend and open, and the electrolyte can diffuse between the molecular chains. The introduction of the liquid-absorbing polymer accelerates the absorption of the electrolyte, increases the electrolyte suck-back rate in the battery cell discharge process, speeds up the transport rate of the electrolyte between the separator and the electrode sheet, reduces electrolyte shortage in the cycle charge-discharge process, reduces battery polarization, and improves the cycle performance of the battery cell. The introduction of the liquid-absorbing polymer also forms a uniform high-wetting point between the separator and the electrode sheet, uniformly improving the wetting performance of the separator and the electrode sheet.

[0072] After the battery cell is formed, the liquid-absorbing polymer creates a three-dimensional interface between the separator and the electrode sheet, further increasing the liquid absorption rate of the separator and electrode sheet, thereby improving the cycle performance of the battery cell.

[0073] In some embodiments, 5 <v / λ<50。

[0074] For example, v / λ may be in the range of 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 any two of the above values.

[0075] In some embodiments, the contact angle between the polymer layer and the electrolyte is in the range of 5° to 25°, and the electrolyte comprises lithium hexafluoride phosphate and an organic solvent. In this application, a standard electrolyte is tested as a test sample, and for specific formulations of the electrolyte, refer to the formulations of the electrolyte in the examples. For example, the electrolyte may comprise lithium hexafluoride phosphate and an organic solvent, the molar concentration of the lithium hexafluoride phosphate is 1 mol / L, and the organic solvent comprises ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1.

[0076] The polymer layer has a liquid-absorbing polymer, and the affinity between the liquid-absorbing polymer and the electrolyte is relatively good, which can improve the wetting performance between the separator and the electrolyte, thereby favoring a further increase in the liquid absorption rate of the separator, and thereby improving the cycle performance of the battery cell. Exemplarily, the range of the contact angle between the polymer layer and the electrolyte may be 5°, 8°, 10°, 12°, 15°, 18°, 20°, 25°, or any two of the above values.

[0077] In the embodiments of this application, the contact angle refers to the angle formed from the polymer layer-electrolyte interface through the electrolyte to the air-electrolyte interface, and may be detected using instruments and methods known in the art. For example, the electrolyte contact angle of the polymer layer of the separator can be tested using a JC2000D goniometer, and the electrolyte may be a standard electrolyte.

[0078] In some embodiments, the basis weight of the liquid absorbent polymer is 0.5 mg / 1540.25 mm 2 ~5mg / 1540.25mm 2 That is the case.

[0079] Selectively, the coating area of ​​the liquid absorbent polymer is 0.5 mg / 1540.25 mm 2 ~2.5mg / 1540.25mm 2 That is the case.

[0080] When the coating basis weight is within the above range, the ability to form a gel-like substance with the electrolyte can be further improved, thereby increasing the liquid absorption rate. For example, the coating basis weight of the liquid-absorbing polymer per unit area of ​​the separator is 0.5 mg / 1540.25 mm². 2 , 0.8mg / 1540.25mm 2 , 1.0 mg / 1540.25 mm 2 , 1.2mg / 1540.25mm 2 , 1.3mg / 1540.25mm 2, 1.5 mg / 1540.25 mm 2 , 2.0 mg / 1540.25 mm 2 , 2.2 mg / 1540.25 mm 2 , 2.5 mg / 1540.25 mm 2 , 3 mg / 1540.25 mm 2 , 3.5 mg / 1540.25 mm 2 , 4 mg / 1540.25 mm 2 , 4.5 mg / 1540.25 mm 2 , 5 mg / 1540.25 mm 2 Or it may be a range consisting of any two of the above values.

[0081] In an embodiment of the present application, the coating basis weight refers to the coating basis weight of the liquid-absorbent polymer on one side of the separator, and can be detected using equipment and methods known in the art. For example, the same master roll substrate and separator are cut into small discs of 1540.25 mm 2 , and the weights of 10 separator small discs are weighed respectively, and the coating basis weight of the liquid-absorbent polymer on the separator can be obtained by calculation.

[0082] In some embodiments, the liquid-absorbent polymer can include one or more of a fluorinated polymer, an ether-based polymer, an ester-based polymer, and a ketoaldehyde-based polymer.

[0083] In some embodiments, the liquid-absorbent polymer includes a fluorinated polymer. The crystallinity measured by differential scanning calorimetry of the fluorinated polymer is Xc1, where 0 < Xc1 ≤ 30%. The melting temperature of the fluorinated polymer is T m1 , with the unit being °C, and 0 < T m1 ≤ 140.

[0084] Crystallization refers to the process of arranging atoms, ions, or molecules in a material in an orderly spatial sequence. The three-dimensional structure of a polymer during the crystallization process is determined by both intramolecular and intermolecular factors, with intermolecular forces influencing the packing density between molecular chains. Crystallinity X C1 This is used to characterize the degree of crystallization of a material and can be measured by differential scanning calorimetry (DSC). Specifically, the measurement step involves taking 0.5g to 0.8g of a sample, placing it in a crucible, and raising and lowering the temperature of the sample under a nitrogen atmosphere at a heating rate of 10°C / min to determine the material's specific T g1 Starting from an initial temperature 20°C lower than that, the material-specific T m1 The temperature is increased to a cutoff temperature 20°C higher than the actual glass transition temperature T of the material, based on the endothermic / exothermic peaks or transition points of the material during the process. g1 and melting temperature T m1 This involves deciding things like that.

[0085] As a result, the crystallinity and melting temperature of the fluorinated polymer are relatively low, the molecular chain arrangement is easily loosened, the inter-molecular forces are small, adjacent molecular chains open easily, and movement of chain segments is achieved by rotation of the molecular chains, forming a highly flexible molecular chain structure. 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.

[0086] As an example, the degree of crystallinity X of a fluorinated polymer measured by differential scanning calorimetry. C1 This may be a range consisting of 5%, 10%, 15%, 20%, 25%, 30%, or any two of the above values.

[0087] For example, the melting temperature of the fluorinated polymer may be in the range of 10°C, 20°C, 50°C, 70°C, 90°C, 100°C, 120°C, 140°C, or any two of the above values.

[0088] In some embodiments, the glass transition temperature of the fluorinated polymer is T g1The unit is °C, and -150 ≤ T g1 The value is ≤60.

[0089] The glass transition temperature is the transition temperature from freezing to migration of a polymer chain segment. The glass transition temperature has a certain effect on the flexibility of the polymer molecular chain; a lower glass transition temperature results in greater flexibility of the polymer molecular chain at room temperature, while a higher glass transition temperature results in less flexibility. The glass transition temperature may be measured by differential scanning calorimetry (DSC). A relatively low glass transition temperature of a polymer results in greater flexibility of the molecular chain segments, and adjacent molecular chains open more easily. Exemplarily, the glass transition temperature of a fluorinated polymer may be in the range of -150°C, -120°C, -100°C, -80°C, -60°C, -30°C, 0°C, 30°C, 60°C, or any two of the above values.

[0090] In some embodiments, the fluorinated polymer comprises at least one of the structural units represented by formula (AI) to formula (AIII), [ka]

[0091] In equations (AI) and (AII), R 11 , R 12 , R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine 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 them contains a fluorine atom.

[0092] If substituted, the substituents may include one or more of nitrile groups (-CN), nitro groups, sulfonic acid groups, sulfonyl groups, amides, carboxyl groups, ester groups, and halogen atoms. The above polymers are merely examples of structural groups of the main molecular chain, and in embodiments of the present application, polymers may be obtained by copolymerization of the above structural groups with a small number of other types of structural groups (e.g., structural units of olefin structural units, ester monomers, nitrile monomers, amide monomers, etc.).

[0093] In equation (AIII), R 15 This includes single-bonded, substituted, or unsubstituted C1-C3 alkyl groups.

[0094] In some embodiments, p is selected from positive integers between 1 and 3.

[0095] In some embodiments, the degree of polymerization n of the fluorinated polymer is selected from a positive integer between 1000 and 30000.

[0096] In some embodiments, R 11 , R 12 , R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C2 alkyl group, and a substituted or unsubstituted C1-C2 alkoxy group, and further selectively, R 11 , R 12 , R 13 and R 14 Each of these independently contains a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0097] In some embodiments, the fluorinated polymer comprises at least one of the structural units represented by formula (AI-1) to formula (AI-11), [ka]

[0098] In some embodiments, the fluorinated polymer comprises at least one of the structural units represented by formula (AII-1) to formula (AII-5), [ka]

[0099] In some embodiments, the fluorinated polymer comprises at least one of the structural units represented by formula (AIII-1) to formula (AIII-3), [ka]

[0100] Exemplary examples include one or more of the following fluorinated polymers: 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).

[0101] Selectively, the fluorinated polymer includes one or more of the following: polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene propylene copolymer (FEP), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE).

[0102] The fluorinated polymer can be derived from one or more of monomers such as fluorocycloethane, fluoroethylene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene and pentafluoropropylene. Optionally, the fluorinated polymer can be derived from at least two of monomers such as fluorocycloethane, fluoroethylene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropene, trifluoropropylene, tetrafluoropropylene and pentafluoropropylene.

[0103] The monomers used in the fluorinated polymer are all short-chain monomers, which are advantageous for forming a linear or short branched-chain structure by polymerization. This structure type has a low degree of entanglement and is advantageous for improving the flexibility of the molecular chain. The molecular chain can fully extend in the electrolyte solution, which is advantageous for the polymer and the electrolyte solution to form a three-dimensional gel-like substance, thereby further increasing the liquid absorption rate.

[0104] In some embodiments, the degree of polymerization n of the fluorinated polymer is selected from positive integers of 5000 to 20000.

[0105] In some embodiments, the molecular weight of the liquid absorbent polymer is 1.2×10 5 g / mol to 1.5×10 6 g / mol, and optionally, 2×10 5 g / mol to 1.5×10 6It is g / mol. When the molecular weight of the polymer is within the above range, it can be ensured that the polymer shows a certain solubility in the electrolyte and at the same time is difficult to be completely dissolved and dispersed by the electrolyte, which is advantageous for controlling the distribution and dispersion of the polymer, and can further improve the flexibility between the molecular chains of the polymer. Since the intermolecular force is relatively weak, it is advantageous for the solvent molecules in the electrolyte to open the molecular chains and enter between the molecular chains, and be wrapped by the molecular chains. Thereby, it is advantageous for active ions to enter the active material through the solvent, and to realize smooth and rapid movement of the active ions.

[0106] When the molecular weight of the liquid-absorbent polymer is within the above range, it can be ensured that the polymer shows a certain solubility in the electrolyte and at the same time is difficult to be completely dissolved and dispersed by the electrolyte, which is advantageous for controlling the distribution and dispersion of the polymer on the surface of the active material, and can further improve the flexibility between the molecular chains of the polymer. Since the intermolecular force is relatively weak, it is advantageous for the solvent molecules in the electrolyte to open the molecular chains and enter between the molecular chains, and be wrapped by the molecular chains. Thereby, it is advantageous for active ions to enter the active material through the solvent, and to realize smooth and rapid movement of the active ions. 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, 1.5×10 6 g / mol or may be in the range composed of any two of the above values.

[0107] [Ether-based polymer]

[0108] In some embodiments, the liquid-absorbent polymer includes 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. The slope of the storage modulus G'-loss modulus G" curve is K1, and 1 < K1 < ∞, Tm2 °C represents the melting temperature of the ether-based polymer.

[0109] Specifically, the manufacturing process for the sheet 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 thin sheet using a flat vulcanizer, and the hot-press temperature is set to (T m2 Set the temperature to +20°C, the rolling thickness to 1-2 mm, the rolling time to 2 min, and the pressure to 8 MPa. After rolling for 2 min, remove the sample and cold press it in another vulcanizer of the same type, setting the cold press pressure to 10 MPa. Using a circular mold with a diameter of 25 mm, a fixed-size polymer disc (sheet-like structure) can be obtained. Exemplarily, the sheet-like structure may be a disc with a thickness of 1-2 mm and a diameter of 25 mm, and samples may be prepared according to the sample standards required for the test equipment.

[0110] According to the conclusions of classical linear viscoelasticity, for polymers, especially linear polymers, the storage modulus G'-loss modulus G'' in the terminal region of the storage modulus G'-loss modulus G'' curve (the interval range approaching the maximum angular velocity) follows a frequency dependence, and the longest chain of the polymer contributes to the viscoelastic behavior.

[0111] The specific steps for the dynamic frequency scanning test are as follows: dynamic frequency scanning is performed using a TA-AR2000EX rotary rheometer (TAinstruments, USA), with parallel plates having a diameter of 25 mm and a thickness of 0.9 mm. To ensure that the test is performed within the linear viscoelastic region, the deflection during the dynamic frequency scanning test is 2%, and the test temperature is T m2 The temperature was +20℃, and the test frequency scan range was 500 rad / s ≤ w 2 The frequency range is ≤0.05 rad / s, which allows us to acquire data in the lowest possible frequency range.

[0112] The dynamic frequency scanning test can characterize the degree of entanglement of molecular chains in the solid-phase melting (molten state). Compared with a linear structure or a short branched-chain structure, a long branched structure, a network structure, and a low cross-linked structure have a high degree of entanglement and show a behavior of deviating from the linear end. The ether-based polymer shows a 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 in the electrolyte between the molecular chains. In addition, since the ether-based polymer still maintains a certain entanglement state of the molecular chains, it can form an electrolyte and a gel-like substance to improve the cycle performance and storage performance of the battery cell.

[0113] 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 values.

[0114] In some embodiments, the glass transition temperature of the ether-based polymer is T g2 where the unit is °C, and -100 ≤ T g2 ≤ 50, and optionally, -80 ≤ Tg2 ≤ 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 values.

[0115] In some embodiments, the ether-based polymer contains a structural unit represented by formula (BI), [Chemical formula]

[0116] In formula (BI), R 21 and R 22 each independently contains a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 23It contains substituted or unsubstituted C1-C5 methylene groups.

[0117] In some embodiments, R 21 and R 22 Each of these independently contains a hydrogen atom and a substituted or unsubstituted C1-C2 alkyl group.

[0118] In some embodiments, R 23 It contains single, substituted, or unsubstituted C1-C4 methylene groups.

[0119] For example, the ether polymer comprises at least one of the structural units represented by formula (BI-1) to formula (BI-8), [ka]

[0120] In some embodiments, the ether polymer comprises a structural unit represented by formula (BII), [ka]

[0121] In equation (BII), R 24 ~R 27 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R 24 ~R 27 At least one of them contains a substituted or unsubstituted C1-C3 alkoxy group or ether group.

[0122] In some embodiments, R 24 ~R 27 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, a substituted or unsubstituted C1-C2 alkoxy group, or an ether group, and R 24 ~R 27 At least one of them contains a substituted or unsubstituted C1-C2 alkoxy group or ether group.

[0123] In some embodiments, the ether polymer comprises at least one of the structural units represented by formula (BII-1) to formula (BII-7), [ka]

[0124] The monomers used in the above-mentioned ether polymers are multi-membered rings, for example, structures with six or fewer members, or short-chain monomers, which are advantageous for forming a high-content -O- structure through polymerization. This structural type has a low degree of entanglement, which is advantageous for improving the flexibility of the molecular chain. The molecular chain can stretch sufficiently in the electrolyte and readily form a gel-like substance with the electrolyte, thereby improving the cycle performance and storage performance of the battery cell.

[0125] The polymers described above are merely examples of structural groups of the main molecular chains, and in embodiments of the present application, polymers may be obtained by copolymerization of the above structural groups with other types of structural groups (e.g., olefin-based structural units, acrylonitrile-based structural units, etc.).

[0126] When the above group is substituted, the substituent may include one or more of the following: a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxyl group, an ester group, or a halogen atom. The above substituent is a high-pressure resistant substituent and is advantageous for stabilizing the polymer structure. The halogen atom may include a fluorine atom, a chlorine atom, a bromine atom, and the like.

[0127] In some embodiments, the degree of polymerization n of the ether polymer is selected from a positive integer between 1500 and 25000.

[0128] Selectively, the degree of polymerization n of the ether polymer is chosen from a positive integer between 3000 and 18000.

[0129] In some embodiments, the molecular weight of the polymer is 1.2 × 10⁻⁶. 5g / mol to 1.0×10 6 g / mol.

[0130] 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 values may also be acceptable.

[0131] "Ester-based polymer"

[0132] In some embodiments, the liquid absorbent polymer includes an ester-based polymer. The ester-based polymer is made 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, where 1 < K2 < ∞, and T m3 °C represents the melting temperature of the ester-based polymer.

[0133] When the ester-based polymer in the embodiments 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 of solvent molecules in the electrolyte between the molecular chains. Also, since the ether-based polymer still maintains a certain entanglement state of the molecular chains, it can form an electrolyte and a gel-like substance, increase the liquid absorption rate, and thereby improve the cycle performance and storage performance of the battery cell.

[0134] In some embodiments, 1 < K2 ≤ 100, and optionally, 1 < K2 ≤ 10.

[0135] 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 values.

[0136] In some embodiments, the glass transition temperature of the ester polymer is T g3 The unit is °C, and -100 ≤ T g3 ≤50, selectively, -80 ≤ T g3 The value is ≤30.

[0137] For example, the glass transition temperature of an ester polymer may be in the range of -100°C, -90°C, -80°C, -60°C, -30°C, 0°C, 30°C, 50°C, or any two of the above values.

[0138] In some embodiments, the ester polymer A comprises a structural unit represented by formula (CI), [ka]

[0139] In equation (CI), R 31 , R 32 and R 33 Each independently contains a hydrogen atom, a substituted or unsubstituted C1-C8 alkyl group, and R 34 It comprises a substituted or unsubstituted C1-C8 alkoxy group, or a substituted or unsubstituted C1-C8 hydroxyalkyl group, and selectively, R 34 This includes a substituted or unsubstituted C1-C6 alkyl group, or a substituted or unsubstituted C1-C6 hydroxyalkyl group.

[0140] Selectively, R 31 This includes a hydrogen atom or a substituted or unsubstituted methyl group.

[0141] Selectively, R 32 and R 33 Each of these independently contains a hydrogen atom.

[0142] Selectively, R 34 This includes substituted or unsubstituted C1-C4 alkyl groups, or substituted or unsubstituted C1-C4 hydroxyalkyl groups.

[0143] For example, the ester polymer comprises at least one of the structural units represented by formula (CI-1) to formula (CI-15), [ka] [ka]

[0144] In some embodiments, the ester polymer A comprises a structural unit represented by formula (CII), [ka]

[0145] In equation (CII), R 35 It contains substituted or unsubstituted C2-C6 methylene groups.

[0146] Selectively, R 35 Each of these independently contains a substituted or unsubstituted C2-C4 methylene group.

[0147] For example, the ester polymer comprises at least one of the structural units represented by formula (CII-1) to formula (CII-5), [ka]

[0148] The above-mentioned ester polymer has a low degree of entanglement of molecular chains, which is advantageous for improving the flexibility of the molecular chains. The molecular chains can stretch sufficiently in the electrolyte and readily form a gel-like substance with the electrolyte.

[0149] The polymers described above are merely examples of structural groups of the main molecular chains, and in embodiments of the present application, polymers may be obtained by copolymerization of the above structural groups with other types of structural groups (for example, monomers having functional groups such as olefin structural units, acrylonitrile structural units, and maleic anhydride).

[0150] When the above group is substituted, the substituent may include one or more of the following: a nitrile group, a nitro group, a sulfonyl group, a carboxyl group, an ester group, a chlorine atom, a fluorine atom, or a bromine atom. The above substituent is a high-pressure resistant substituent and is advantageous for stabilizing the polymer structure.

[0151] In some embodiments, the degree of polymerization n of the ester polymer is selected from a positive integer between 800 and 20000.

[0152] Selectively, the degree of polymerization n of the ester polymer is chosen from a positive integer between 1000 and 15000.

[0153] In some embodiments, the molecular weight of the polymer is 1.2 × 10⁻⁶. 5 g / mol ~ 1.0 × 10 6 It is g / mol.

[0154] For example, the molecular weight of the polymer is 1.2 × 10⁻⁶. 5 g / mol, 2 × 10⁻⁶ 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1 × 10⁻⁶ 6 g / mol, 1.5 × 10 6 It may be g / mol or a range consisting of any two of the above values.

[0155] [Ketone aldehyde polymers]

[0156] In some embodiments, the liquid absorbent polymer comprises a ketone aldehyde polymer, the ketone aldehyde polymer is prepared into a sheet-like structure, and the sheet-like structure is subjected to (T m4 A dynamic frequency scanning test was performed at +20°C to obtain the storage modulus G'-loss modulus G'' curve, and the slope of the storage modulus G'-loss modulus G'' curve was K3, where 0.8 ≤ K3 < ∞, T m4 °C represents the melting temperature of the ketone aldehyde polymer.

[0157] In some embodiments, 0.8 ≤ K3 ≤ 100, and selectively, 0.8 ≤ K3 ≤ 10.

[0158] For example, K3 may be a range consisting of 0.8, 0.9, 1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or any two of the above values.

[0159] In some embodiments, the glass transition temperature of the ketone aldehyde polymer is T g4 The unit is °C, and -100 ≤ T g4 ≤50, selectively, -80 ≤ T g4 The value is ≤30.

[0160] For example, the glass transition temperature of a ketone aldehyde polymer may be in the range of -100°C, -90°C, -80°C, -60°C, -30°C, 0°C, 30°C, 50°C, or any two of the above values.

[0161] In some embodiments, the ketone aldehyde polymer comprises a structural unit represented by formula (DI), [ka]

[0162] In equation (DI), R 41 It contains single bonds, substituted or unsubstituted C1-C6 methylene groups, R 42 It contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group,

[0163] Selectively, R 41 It contains single bonds, substituted or unsubstituted C1-C2 methylene groups,

[0164] Selectively, R 42 It contains a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group.

[0165] In the embodiments of the present application, a single bond indicates that there is no group and the atoms on both sides of the group are connected by a single bond, for example, R 41 This is a single bond, and this is R 41 This indicates that the carbon atoms on both sides are connected by a single bond.

[0166] For example, the ketone aldehyde polymer comprises at least one of the structural units represented by formula (DI-1) to formula (DI-6), [ka]

[0167] For example, the ketone aldehyde polymer comprises a structural unit represented by formula (DII), [ka]

[0168] In equation (DII), R 43 ~R 46 Each independently comprises a hydrogen atom, a hydroxyl 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, where r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from positive integers, selectively R 43 ~R 46 Each of these independently comprises a hydrogen atom, a hydroxyl 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.

[0169] In some embodiments, the ketone aldehyde polymer comprises at least one of the structural units represented by formula (DII-1) to formula (DII-4), [ka]

[0170] The entanglement degree of the molecular chains of the above ketone aldehyde-based polymer is low, which is advantageous for improving the flexibility of the molecular chains. The molecular chains can fully extend in the electrolyte, which is advantageous for forming an electrolyte and a gel substance.

[0171] The above polymer is only an example of the structural group of the main molecular chain. In the embodiments of the present application, the polymer may be obtained by copolymerization of the above structural group and other types of structural groups (for example, olefin-based structural units, enol-based structural units, acrylonitrile-based structural units, etc.).

[0172] When the above group is substituted, the substituent can include one or more of a nitrile group (-CN), a nitro group, a sulfonyl group, a carboxyl group, an ester group, a chlorine atom, a fluorine atom, and a bromine atom. The above substituent is a high-pressure-resistant substituent, which is advantageous for stabilizing the structure of the polymer.

[0173] In some embodiments, the degree of polymerization n of the ketone aldehyde-based polymer is selected from positive integers of 500 to 15000.

[0174] Optionally, the degree of polymerization n of the ketone aldehyde-based polymer is selected from positive integers of 500 to 10000.

[0175] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol to 1.0×10 6 g / mol.

[0176] Exemplarily, the molecular weight of the polymer may be 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 6 g / mol or a range consisting of any two of the above values.

[0177] Embodiments of the present invention can further improve the reliability and cycle performance of battery cells if the liquid absorbent polymer further satisfies one or more of the following conditions.

[0178] In some embodiments, the liquid absorbent polymer 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, then at 25°C for ≥24 hours, followed by two-stage standing treatments, after which a portion of the polymer system is transformed into a gel-like substance by swelling and adsorption, and then the polymer system is filtered through a 200-mesh filter to retain the first substance. The liquid absorbent polymer has a mass of q and its unit is g, the first substance has a mass of m and its unit is g, and the polymer and the first substance satisfy 5 ≤ m / q ≤ 1000, selectively 10 ≤ m / q ≤ 1000, and more selectively 10 ≤ m / q ≤ 50. For example, m / q may be in the range of 5, 10, 20, 25, 28, 30, 32, 35, 40, 50, 80, 100, 200, 500, 1000, or any two of the above values.

[0179] For example, based on the mass of the polymer system, the ratio of the mass content of the liquid absorbent polymer to the mass content of the first solvent is in the range of 1:100 to 1:10, for example, 3:50.

[0180] Exemplary, the first solvent is the same as or similar to the solvent of the electrolyte and may include at least one of carbonate solvents and ether solvents. For example, carbonate solvents include cyclic carbonate solvents and / or linear carbonate solvents.

[0181] Examples of cyclic carbonate solvents include one or more of ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinylethylene carbonate (VEC), and dioctyl carbonate (CC).

[0182] Examples of linear carbonate solvents include one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), diphenyl carbonate (DPC), methyl allyl carbonate (MAC), and polycarbonate (VA).

[0183] Examples of ether solvents include one or more of the following: tetrahydrofuran (THF), 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane (DOL), dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), and diglyme (DG).

[0184] Selectively, the first solvent may simultaneously contain a lithium salt and electrolyte additives such as lithium hexafluorophosphate, vinylene carbonate (VC), and fluorinated vinylene carbonate (FEC).

[0185] In this application, m / q, also known as the precipitation value, characterizes the ability of the liquid-absorbing polymer and solvent to transform into a gel-like substance.

[0186] The first substance mainly consists of a gel-like substance formed from a liquid-absorbing polymer and a first solvent, and in such a gel-like substance, the molecular structure of the polymer remains essentially unchanged.

[0187] In some embodiments, the first substance was dried at 80°C for 12 hours, the first solvent was removed from the first substance, and detection by infrared spectrophotometric (IR) or nuclear magnetic resonance (NMR) testing was performed. The results showed that the main component of the dried first substance was the liquid absorbent polymer described above.

[0188] The relevant parameters of the liquid absorbent polymer of this application may be detected using the following method:

[0189] The base of the liquid absorbent polymer in the embodiments of the present invention may be detected using infrared spectrophotometry (IR), specifically, the liquid absorbent polymer is tested with a Thermo Nicolet Nexus 670 attenuated total reflection Fourier transform infrared spectrometer (FTIR-ATR), then tested according to standard GB / T6040-2002, with a test range of 600-4000 cm⁻¹ by the ATR method. -1 The reproducibility is ±2cm. -1 The resolution is 4cm -1 It is superior to [another material], with a penetration depth of 0.2 to 0.6 μm.

[0190] The structure of the liquid absorbent polymer of the embodiment of the present invention may also be tested by nuclear magnetic resonance (NMR), specifically, 1H NMR and 13C NMR are performed in a Varian Mercury Plus-400 nuclear magnetic resonance spectrometer at a test temperature of 20°C, with TMS as the internal standard, CDCl3 as the solvent, and a proton resonance frequency of 400 MHz.

[0191] The polymer monomer type of the liquid absorbent polymer according to the embodiment of the present invention (particularly suitable for monomers that make up a small proportion of the polymer) can be tested using pyrolysis gas chromatography-mass spectrometry. The specific test steps are as follows: accurately weigh 0.5 mg of the sample, place it in a sample cup, fix it to an injection rod, and then place it in a cracker attached near the GC (gas chromatography) inlet. Once the cracker reaches a set temperature, press the injection button, causing the sample cup to rapidly fall into the center of the cracking furnace by free fall. In an inert gas N2 atmosphere, the volatile components instantly evaporate, are carried to a gas chromatography column by a carrier gas, separated, and finally detected by a flame ionization detector (FID) or mass spectrometer (MS) to obtain a gas chromatogram or total ion chromatogram.

[0192] The molecular weight of the liquid absorbent polymer in the embodiments of this application is in the sense known in the art and may be measured using instruments and methods commonly used in the art, or tested by gel permeation chromatography (GPC). The specific test steps are as follows: take an appropriate amount of the sample to be tested (ensure an opacity of 8% to 12% of the sample concentration), add 20 ml of deionized water, and simultaneously irradiate with ultrasound externally for 5 min (53 kHz / 120 W) to ensure that the sample is completely dispersed, and then measure the sample according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0193] Alternatively, the test is performed using a multi-angle laser scattering (MALLS) system, specifically a combination of a GPC, a Dawn Heleos II multi-angle laser light scattering system, an Optilab T-rEX refractive index (RI) detector, and a Visco Star II viscometer (Wyatt Technology Corporation, USA). The test is performed at 30°C, using tetrahydrofuran as the mobile phase, at a flow rate of 1.0 ml / min, and the SEC-SAMLL data is processed using the commercially available software ASTRA6 to obtain molecular weight parameters.

[0194] The cycle performance of the battery cell can be further improved if the liquid absorbent polymer of the embodiment of the present invention further satisfies one or more of the following conditions.

[0195] In some embodiments, a liquid absorbent polymer 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 h and then at 25 °C for ≥ 24 h, followed by a two-stage standing treatment. Thereafter, a part of the polymer system is changed into a gel-like substance by swelling and adsorption. Next, the polymer system is filtered through a 200-mesh filter screen to leave a first substance. The liquid absorbent polymer has a mass of q, with the unit being g. The first substance has a mass of m, with the unit being g. The liquid absorbent polymer and the first substance satisfy 5 ≤ m / q ≤ 1000, optionally 10 ≤ m / q ≤ 1000, and more optionally 10 ≤ m / q ≤ 50. Exemplarily, m / q may 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 above values.

[0196] Exemplarily, based on the mass of the polymer system, the ratio of the mass content of the polymer to the mass content of the first solvent is in the range of 1:100 to 1:10, for example 3:50.

[0197] Exemplarily, the first solvent is the same as or similar to the solvent of the electrolyte and can include at least one of a carbonate-based solvent and an ether-based solvent. For example, the carbonate-based solvent can include a cyclic carbonate solvent and / or a linear carbonate solvent.

[0198] As an example of the cyclic carbonate solvent, the cyclic carbonate solvent can include one or more of ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC) and dioctyl carbonate (CC).

[0199] As an example of the linear carbonate solvent, the linear carbonate solvent can include one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), diphenyl carbonate (DPC), methyl allyl carbonate (MAC) and polycarbonate (VA).

[0200] Examples of ether solvents include one or more of the following: tetrahydrofuran (THF), 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane (DOL), dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), and diglyme (DG).

[0201] Selectively, the first solvent may simultaneously contain a lithium salt and electrolyte additives such as lithium hexafluorophosphate, vinylene carbonate (VC), and fluorinated vinylene carbonate (FEC).

[0202] In this application, m / q, also known as the precipitation value, characterizes the ability of the liquid-absorbing polymer and solvent to transform into a gel-like substance.

[0203] The first substance mainly consists of a gel-like substance formed from a liquid-absorbent polymer and a first solvent, and in such a gel-like substance, the molecular structure of the liquid-absorbent polymer remains essentially unchanged.

[0204] In some embodiments, the first substance was dried at 80°C for 12 hours, the first solvent was removed from the first substance, and detection by infrared spectrophotometric (IR) or nuclear magnetic resonance (NMR) testing was performed. The results showed that the main component of the dried first substance was the liquid absorbent polymer described above.

[0205] The embodiments of this invention enable the extension of the molecular chains of the liquid absorbent polymer within the safe operating temperature range of the battery cell by increasing the temperature, thereby promoting mutual attraction and physical bonding between the polymer molecular chains and the electrolyte. At room temperature, the molecular chain segments of the liquid absorbent polymer become less active and remain attached to the surface of the separator body, trapping the electrolyte in the spatial environment where the liquid absorbent polymer is located and forming a gel or gel-like state. This increases the transport rate of active ions such as lithium ions, thereby improving cycle performance and storage performance.

[0206] In embodiments of the present application, the separator comprises a separator body and a polymer layer, the polymer layer being installed on at least one surface of the separator body, meaning that the polymer layer may be installed on one side of the separator body or on both sides of the separator body. Since the structural form of the separator body varies, the arrangement of the polymer layer also varies accordingly. The liquid absorbent polymer can be dispersed in a solvent to form a polymer mixture system, which is applied to the separator body by coating processes such as atomizing spray and gravure coating.

[0207] In some embodiments, the separator body includes a substrate, and the polymer layer is installed on at least one surface of the substrate.

[0208] In some other embodiments, the separator body comprises a substrate and a heat-resistant coating layer, the heat-resistant coating layer being installed on at least one surface of the substrate, and the polymer layer being installed on the surface of the heat-resistant coating layer away from the substrate. It is understood that the heat-resistant coating layer may be installed on one or both sides of the substrate.

[0209] In embodiments of the present application, the material of the substrate is not particularly limited, and any well-known substrate with excellent chemical and mechanical stability can be used. For example, the substrate may include at least one of porous polyolefin resin films (e.g., polyethylene, polypropylene, and polyvinylidene fluoride), porous glass fibers, and porous nonwoven fabrics. The substrate may be a single layer film or a multilayer composite film. If the substrate is a multilayer composite film, the materials of each layer may be the same or different.

[0210] In some embodiments, the porosity of the substrate is 25% or more, and selectively between 25% and 50%. When the porosity of the substrate is within the above range, the permeability of the substrate can be improved, which is advantageous for the movement of active ions. Furthermore, because the porosity is relatively low, the mechanical properties of the substrate can also be improved, and it can provide a good support role for the polymer layer.

[0211] In some embodiments, the thickness of the substrate may be 16 μm or less, and selectively between 5 μm and 12 μm. For example, the thickness of the substrate may be in the range of 1 μm, 2 μm, 3 μm, 5 μm, 10 μm, 12 μm, 15 μm, 16 μm, or any two of the above values.

[0212] 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 resistance of the separator can be improved.

[0213] In some embodiments, the mass percentage of inorganic particles in the heat-resistant coating layer is ≤30. Exemplarily, the mass percentage of inorganic particles in the heat-resistant coating layer may be in the range of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, or any two of the above values.

[0214] The inorganic particles may include at least one of the following: inorganic particles having a dielectric constant of 5 or more; inorganic particles having active ion transport capability; and inorganic particles capable of electrochemical oxidation and reduction.

[0215] In some embodiments, inorganic particles having a dielectric constant of 5 or more include boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), and silicon dioxide compounds (SiO2). x(0 < x ≤ 2), tin dioxide (SnO2), titanium dioxide (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) can include at least one of them.

[0216] In some embodiments, the inorganic particles having active ion transport ability are 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 glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO 3、 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 zcan include at least one of (0 < x < 3, 0 < y < 3, 0 < z < 7).

[0217] In some embodiments, the inorganic particles capable of electrochemical oxidation and reduction can 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.

[0218] In some embodiments, the heat-resistant coating layer can further include other organic particles. For example, the organic particles can include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenol resin, polypropylene, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramide, polyamideimide, polyimide, a copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0219] In some embodiments, the heat-resistant coating layer can further include an adhesive. As an example, the adhesive can include at least one of an aqueous acrylic resin (e.g., a homopolymer of acrylic acid, methacrylic acid, sodium acrylate monomer or a copolymer with other comonomers), polyvinyl alcohol (PVA), an isobutylene-maleic anhydride copolymer, and polyacrylamide.

[0220] In some embodiments, the thickness of the heat-resistant coating layer can be ≦ 4 μm. This contributes to increasing 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 on one side of the substrate. Exemplarily, the thickness of the heat-resistant coating layer can 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 above values.

[0221] In some embodiments, the polymer layer may further contain heat-resistant particles, and the synergistic effect between the heat-resistant particles and the liquid-absorbing polymer can further improve the overall heat resistance and ion transport performance of the separator. The liquid-absorbing polymer and heat-resistant particles can be dispersed in a solvent to form a polymer mixture system, which is then applied onto the separator body by coating processes such as atomizing spraying and gravure coating.

[0222] In some embodiments, based on the total mass of the polymer layer, the ratio of the mass percentage of the liquid-absorbing polymer to the mass percentage of the heat-resistant particles is (0.2 to 5.0):1, and selectively (0.5 to 2.0):1. When the content of heat-resistant particles and liquid-absorbing polymer is within the above range, the overall heat resistance and ion transport performance of the separator can be further improved. For example, the ratio of the mass percentage of the liquid absorbent polymer to the mass percentage of the heat-resistant particles may be within the range of 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 two of the above values.

[0223] In some embodiments, the thickness of the polymer layer may be 0.5 μm to 3.0 μm, and selectively 1.0 μm to 2.0 μm. When the thickness of the polymer layer is within the above range, the overall heat resistance and ion transport performance of the separator can be further improved. For example, the thickness of the polymer layer may be in the range of 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 any two of the above values.

[0224] battery cell

[0225] In a second aspect, an embodiment of the present application provides a battery cell comprising an electrode assembly and an electrolyte, wherein the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator, the separator being positioned between the positive electrode sheet and the negative electrode sheet, and the separator includes a separator of any embodiment of the first aspect of the present application.

[0226] [Positive electrode sheet]

[0227] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer placed on at least one surface of the positive electrode current collector.

[0228] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode active material layer is installed on one or both of the two opposing surfaces of the positive electrode current collector.

[0229] The positive electrode active material layer comprises a positive electrode active material, which may be a positive electrode active material known in the art for battery cells. For example, the positive electrode active material may include at least one of lithium-containing phosphate compounds, lithium-containing transition metal oxides, sodium-containing phosphate compounds, and sodium-containing transition metal oxides.

[0230] For example, the general formula for olivine-type phosphate active materials (lithium-containing phosphate compounds) is Li x A y Me a M b P 1-c X c Y zTherefore, 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 contains one or more of Na, K and Mg, Me contains one or more of Mn, Fe, Co and Ni, M contains 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 contains one or more of S, Si, Cl, B, C and N, and Y contains one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0231] Exemplary examples include lithium transition metal oxides (ternate, lithium nickelate / sodium, lithium cobaltate / sodium, lithium manganate / sodium, lithium-rich layered and rock salt phase layered materials, etc.). The general formula for layered cathode active materials is Li x A y Ni a Co b Mn c M (1-a-b-c) Y z The values ​​are 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, 1.8≦z≦3.5, A contains one or more of Na, K and Mg, M contains 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 contains one or more of O and F. Selectively, y=0. Specifically, the layered cathode active material is lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), 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 contain one or more of O2 (NCM811) and NCA.

[0232] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. Examples of metal foil sheets include aluminum foil or aluminum alloy foil. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include one or more combinations selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The polymer material base layer may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0233] In some embodiments, the positive electrode active material layer further selectively comprises a positive electrode conductive agent. In embodiments of the present application, the type of positive electrode conductive agent is not particularly limited, and as an example, the positive electrode conductive agent includes one or more combinations selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is 5% or less based on the total mass of the positive electrode active material layer.

[0234] In some embodiments, the positive electrode active material layer further selectively comprises a positive electrode adhesive. In embodiments of the present application, the type of positive electrode adhesive is not particularly limited, and as an example, the positive electrode adhesive may include one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene tur copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tur copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin. In some embodiments, the mass percentage of the positive electrode adhesive is 5% or less based on the total mass of the positive electrode active material layer. The crystallinity of the positive electrode adhesive is higher compared to the crystallinity of the fluorinated polymer according to embodiments of the present application. The melting temperature of the positive electrode adhesive is higher compared to the melting temperature of the fluorinated polymer according to embodiments of the present application.

[0235] The positive electrode active material layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, a selective conductive agent, a selective adhesive, and other optional components in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP). Of course, the preparation of the positive electrode sheet is not limited to the above method, and the above-described preparation methods can also be used.

[0236] [Negative electrode sheet]

[0237] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector and having a negative electrode active material.

[0238] Exemplary, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode active material layer is installed on one or both of the two opposing surfaces of the negative electrode current collector.

[0239] The anode active material can be any anode active material known in the art for battery cells. For example, the anode active material may include, but is not limited to, natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of silicon monomer, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material may include at least one of tin monomer, tin oxide, and tin alloy material.

[0240] In some embodiments, the negative electrode active material layer further selectively comprises 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 dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent is ≤5% based on the total mass of the negative electrode active material layer.

[0241] In some embodiments, the negative electrode active material layer further selectively comprises a negative electrode adhesive. In embodiments of the present application, the type of negative electrode adhesive is not particularly limited, and as an example, the negative electrode adhesive may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin (SR-1B), aqueous acrylic resin (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS)), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode adhesive is ≤5% based on the total mass of the negative electrode active material layer.

[0242] In some embodiments, the negative electrode active material layer selectively further comprises other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC) or PTC thermistor material. In some embodiments, the mass percentage of the other additives is ≤2% based on the total mass of the negative electrode active material layer.

[0243] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. Copper foil can be used as an example of a metal foil sheet. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0244] The negative electrode active material layer is typically formed by coating a negative electrode slurry onto a negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing a negative electrode active material, a selective conductive agent, a selective adhesive, and other selective auxiliary agents in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP) or deionized water. The preparation of the negative electrode sheet is not limited to the above method, and the above-described preparation methods may also be used.

[0245] The negative electrode sheet does not preclude any 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 a binder) placed on the surface of the negative electrode current collector, sandwiched between the negative electrode current collector and the negative electrode active material layer. In some other embodiments, the negative electrode sheet described herein also includes a protective layer covering the surface of the negative electrode active material layer.

[0246] [Electrolyte]

[0247] In the charging and discharging process of a battery cell, active ions reciprocate between the positive and negative electrode sheets, becoming embedded and detached, while the electrolyte plays a role in conducting these active ions between the positive and negative electrode sheets. In this application, the type of electrolyte is not particularly limited and can be selected according to actual requirements.

[0248] The electrolyte solution comprises an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not specifically limited and may be selected according to actual requirements.

[0249] If the battery cell of the present invention is a lithium-ion battery, the electrolyte salt may, for example, include, but is not limited to, at least one of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonimide (LiFSI), bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoroborate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0250] If the battery cell of the present invention is a sodium-ion battery, the electrolyte salt may, for example, include, but is not limited to, at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromesylate (NaTFS), sodium difluoroborate (NaDFOB), sodium difluoroborate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodisoxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0251] For example, the solvents include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), and propionate. This material may contain, but is not limited to, one or more of the following: ethyl acid (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl sulfone (EMS), diethyl sulfone (ESE), tetrahydrofuran (THF), 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane (DOL), dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), and diglyme (DG).

[0252] In some embodiments, the electrolyte also selectively includes additives. For example, the additives may include additives for forming a negative electrode film, additives for forming a positive electrode film, and additives that can improve several aspects of the battery's performance, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature power performance.

[0253] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet may be fabricated into an electrode assembly by a winding process and / or a lamination process.

[0254] In some embodiments, the battery cell may include an outer casing. This casing may be used to package the electrode assembly and the electrolyte.

[0255] In some embodiments, the casing of the battery cell may be a rigid case, such as a hard plastic case, an aluminum case, or a steel case. The casing of the battery cell may also be a soft case, such as a bag-shaped soft case. The material of the soft case may be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0256] In some embodiments, the positive electrode sheet, separator, and negative electrode sheet may be fabricated into an electrode assembly by a winding process or a lamination process.

[0257] In this application, the shape of the battery cell is not particularly limited and may be cylindrical, rectangular, or any other shape. Figure 1 shows a rectangular battery cell 5 as one example.

[0258] In some embodiments, as shown in Figures 1 and 2, the exterior may include a case 51 and a cover plate 53. Here, the case 51 includes a bottom plate and side plates connected to the bottom plate, with the bottom plate and side plates surrounding each other to form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 is used to cover this opening and seal the housing cavity. The positive electrode sheet, negative electrode sheet, and separator may be fabricated into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and may be adjusted according to the needs.

[0259] The method for manufacturing the battery cell of the present invention is well known. In some embodiments, a battery cell can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly by a winding process or a lamination process, the electrode assembly can be placed inside an outer casing, the electrolyte can be injected after drying, and a battery cell can be obtained through processes such as vacuum packaging, settling, chemical conversion, and shaping.

[0260] In some embodiments of the present invention, the battery cells according to the present invention may be assembled into a battery module, and the number of battery cells included in the battery module may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0261] Figure 3 is a schematic diagram of a battery module 4 as one example. As shown in Figure 3, in the battery module 4, multiple battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may also be arranged according to any other method. Furthermore, multiple battery cells 5 can be fixed together with fasteners.

[0262] Selectively, the battery module 4 may further include a case having a housing space, in which multiple battery cells 5 are housed.

[0263] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0264] Both the battery module 4 and the battery pack can be used as specific examples of batteries in the embodiments of the present invention.

[0265] Figures 4 and 5 are schematic diagrams of a battery pack 1 as one example. As shown in Figures 4 and 5, the battery pack 1 may include a battery housing and a plurality of battery modules 4 installed within the battery housing. The battery housing includes an upper housing 2 and a lower housing 3, the upper housing 2 being used to cover the lower housing 3 and form a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged within the battery housing in any manner.

[0266] power consumption equipment

[0267] In a third aspect, the present application provides a power consumption device comprising at least one of the battery cells, battery modules, and battery packs of the present application. The battery cells, battery modules, and battery packs can function as a power source for the power consumption device and can also function as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (such as mobile phones and laptops), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks), trains, ships, and satellites, and energy storage systems. The power consumption device can select a battery cell, battery module, or battery pack depending on its usage needs. Figure 6 is a schematic diagram of a power consumption device as one example. The power consumption device 6 is such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the needs for high power output and high energy density of the power consumption device, a battery pack 1 or a battery module can be used. Another example of a power consumption device may be a mobile phone, tablet, or laptop. Since such a power consumption device requires lightness and thinness, a battery cell can be used as a power source.

[0268] Examples

[0269] The following describes embodiments of the present application. The embodiments described below are illustrative and are for illustrative purposes only, and should not be understood as limiting the present application. If specific techniques or conditions are not specified in the embodiments, they should be carried out in accordance with the techniques or conditions described in the literature of the art or in the product description. If the manufacturer of the reagents or equipment used is not specified, commercially available conventional products may be used.

[0270] Example 1: Fabrication of a lithium-ion battery

[0271] (1) Preparation of the positive electrode sheet:

[0272] A 12μm thick aluminum foil was used as the positive electrode current collector.

[0273] Cathode active material LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), conductive carbon black, and adhesive polyvinylidene fluoride (PVDF) were added to an appropriate amount of N-methylpyrrolidone (NMP) and thoroughly stirred to prepare a positive electrode slurry. The mass ratio of NCM622, conductive carbon black, PVDF, and N-methylpyrrolidone (NMP) in the positive electrode slurry was 97.5:1.4:1.1. The positive electrode slurry was applied to aluminum foil current collector, vacuum-dried at 100°C, cold-pressed, then trimmed, cut, and slit, and finally dried at 85°C under vacuum conditions for 4 hours to prepare a positive electrode sheet.

[0274] (2) Fabrication of the negative electrode sheet:

[0275] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0276] A negative electrode slurry was prepared by uniformly mixing synthetic graphite as the negative electrode active material, carbon black as the conductive agent, styrene-butadiene rubber (SBR) as the adhesive, and sodium hydroxymethylcellulose (CMC) as the thickener in a weight ratio of 97.4:2:0.5:0.1, and adding it to deionized water. The negative electrode slurry was applied to the copper foil of the current collector, vacuum-dried at 85°C, cold-pressed, trimmed, cut, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0277] (3) Preparation of electrolyte:

[0278] Under conditions with a water content of less than 10 ppm, 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. Then, lithium salt LiPF6 was mixed with the resulting solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0279] (4) Fabrication of separators

[0280] A 7μm polyethylene film (PE) was used as the base material.

[0281] A liquid absorbent polymer was dispersed in dimethyl carbonate (DMC) solvent to form a mixed system. This mixed system was atomized and sprayed onto both sides of a polyethylene film to form polymer layers on each side. The atomizing solvent was water, and the mass content of the mixed system was 1%.

[0282] (5) Manufacturing of lithium-ion batteries:

[0283] To ensure that the separator is positioned between the positive electrode sheet and the negative electrode sheet and serves as an isolation, the positive electrode sheet, separator, and negative electrode sheet are sequentially stacked, then wound together to obtain an electrode assembly. The electrode assembly is then placed in an outer case, dried, and then the electrolyte is injected. A lithium-ion battery is obtained through processes such as vacuum packaging, standing, chemical formation, and shaping.

[0284] Comparative Example 1

[0285] A lithium-ion battery was prepared using the same method as in Example 1, but unlike Example 1, the separator in Comparative Example 1 is a 7 μm polyethylene film (PE).

[0286] Comparative Example 2

[0287] A lithium-ion battery was fabricated using the same method as in Example 1, but unlike Example 1, the material of the liquid-absorbing polymer separator in Comparative Example 2 was changed.

[0288] Examples 1-2 to Examples 1-5

[0289] A lithium-ion battery was fabricated using the same method as in Example 1, but unlike Example 1, the basis weight of the polymer layer of the separator in Examples 1-2 to 1-5 was adjusted.

[0290] Examples 2-1 to 2-3

[0291] A lithium-ion battery was fabricated using the same method as in Example 1, but unlike Example 1, the material of the liquid-absorbent polymer separator was changed from Examples 2-1 to Examples 2-3.

[0292] Examples 3-1

[0293] A lithium-ion battery was fabricated using the same method as in Example 1, but unlike Example 1, the arrangement of the polymer layer of the separator in Examples 4-1 was adjusted. Specifically, the separator fabrication step was as follows:

[0294] The steps include using a 7μm polyethylene film (PE) as the substrate for the separator,

[0295] The process includes the step of uniformly mixing silicon oxide particles and an aqueous adhesive type polyacrylic acid in an appropriate amount of deionized water as a solvent in a mass ratio of 20:80 to obtain a coating slurry.

[0296] The prepared coating slurry was applied to both sides of the PE substrate using a coater to form a heat-resistant coating layer.

[0297] A liquid absorbent polymer was dispersed in dimethyl carbonate (DMC) solvent to form a mixture. This mixture was atomized and sprayed onto the surface of a heat-resistant coating layer to form a polymer layer, thereby obtaining a separator. The atomizing solvent was water, and its mass content in the mixture was 1%.

[0298] Examples 3-2 to 3-6

[0299] A lithium-ion battery was fabricated in the same manner as in Example 1, but unlike Example 1, the composition of the polymer layer of the separator in Examples 3-2 to 3-6 was adjusted. Specifically, the separator fabrication step was as follows:

[0300] The steps include using a 7μm polyethylene film (PE) as the substrate for the separator,

[0301] The method includes the steps of: dispersing silicon oxide particles and a liquid absorbent polymer in a dimethyl carbonate (DMC) solvent to form a mixed system; atomizing this mixed system and spraying it onto the surface of a heat-resistant coating layer to form a polymer layer and thereby obtain a separator. Here, the mass ratio of silicon oxide particles to liquid absorbent polymer in Examples 4-2 is 1.5:1, the mass ratio of silicon oxide particles to liquid absorbent polymer in Examples 4-3 is 0.5:1, the mass ratio of silicon oxide particles to liquid absorbent polymer in Examples 4-4 is 2:1, the mass ratio of silicon oxide particles to liquid absorbent polymer in Examples 4-5 is 0.2:1, and the mass ratio of silicon oxide particles to liquid absorbent polymer in Examples 4-5 is 0.5:1.

[0302] The data for the examples and comparative examples are shown in Table 1.

[0303] Test section

[0304] 1. Performance testing of lithium-ion batteries

[0305] 45℃ 1C / 1C 1600 cycle capacity retention

[0306] A lithium-ion battery was charged to 4.25V at 45°C with a constant current of 1C, then charged again to 1C at a constant voltage of 4.25V, and finally discharged to 2.8V with a constant current of 1C. This constitutes one charge-discharge cycle. The capacity retention rate after 1600 cycles was calculated, with the initial discharge capacity set to 100%. Capacity retention rate (%) of a lithium-ion battery after 1600 cycles = Discharge capacity at 1600 cycles / Initial discharge capacity × 100%.

[0307] Test results

[0308] The test results are shown in Table 1.

[0309] Table 1

[0310] [Table 1-1] [Table 1-2]

[0311] In Table 1, 80% ethylene oxide refers to a molar percentage of ethylene oxide that is 80%, based on the total molar amount of ethylene oxide and 2-ethylethylene oxide.

[0312] As can be seen from Table 1, the contact angle in Comparative Example 1 refers to the contact angle between the separator surface (substrate) and the electrolyte.

[0313] Compared to Comparative Example 1, the present invention's embodiment includes the present invention's liquid-absorbing polymer added to the separator, improving the cycle performance of the lithium-ion battery. In Comparative Example 2, although a polymer was added to the separator, 100% ethylene oxide does not have high liquid absorption, resulting in low liquid absorption of the separator and little improvement in the battery cell's cycle performance.

[0314] Compared to Comparative Examples 1 and 2, in the embodiment of the present invention, a polymer layer is provided on the surface of the separator, and the polymer layer is in contact with the electrolyte. By introducing a liquid-absorbing polymer, the absorption of the electrolyte is accelerated, the electrolyte suck-back rate in the battery cell discharge process is increased, the transport rate of the electrolyte between the separator and the electrode sheet is increased, electrolyte shortage in the cycle charge-discharge process is reduced, battery polarization is reduced, and the cycle performance of the battery cell can be improved. Furthermore, the liquid-absorbing polymer creates a three-dimensionally interconnected interface between the separator and the electrode sheet, further increasing the liquid absorption rate between the separator and the electrode sheet, thereby improving the cycle performance of the battery cell.

[0315] While this application has been described with reference to preferred embodiments, various improvements and substitutions of components can be made without departing from the scope of this application. In particular, each technical feature mentioned in each embodiment can be combined in any way, provided that no structural conflicts exist. This application is not limited to the specific embodiments disclosed in the specification, but includes all technical solutions that fall within the claims.

Claims

1. A separator, The separator body and A polymer layer is provided on at least one surface of the separator body, wherein the polymer layer includes a polymer layer containing a liquid absorbent polymer. Here, the separator satisfies v / λ > 5.00, λ represents the porosity of the separator, A separator in which v represents the liquid absorption rate of the separator, and its unit is mg / s.

2. The separator is the separator according to claim 1, satisfying 5 < v / λ < 50.

3. The separator according to claim 1 or 2, wherein the contact angle between the polymer layer and the electrolyte is in the range of 5° to 25°, the electrolyte comprises lithium hexafluoride phosphate and an organic solvent, the molar concentration of the lithium hexafluoride phosphate is 1 mol / L, and the organic solvent comprises ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate in a volume ratio of 1:1:

1.

4. The coating area of ​​the liquid absorbent polymer on the separator is 0.5 mg / 1540.25 mm². ２ ~5mg / 1540.25mm ２ The separator according to any one of claims 1 to 3.

5. The aforementioned liquid absorbent polymer includes a fluorinated polymer, The degree of crystallinity of the fluorinated polymer, as measured by differential scanning calorimetry, is X Ｃ１ Therefore, 0 < X Ｃ１ ≤30%, The melting temperature of the fluorinated polymer is T ｍ１ The unit is °C, and 0 < T ｍ１ A separator according to any one of claims 1 to 4, wherein the size is ≤ 140.

6. The glass transition temperature of the fluorinated polymer is T ｇ１ The unit is °C, and -150 ≤ T ｇ１ The separator according to claim 5, wherein the value is ≤ 60.

7. The fluorinated polymer comprises at least one of the structural units represented by formula (AI) to formula (AIII), 【Chemistry 1】 In formula (AI) and formula (AII), R １１ , R １２ , R １３ and R １４ each independently includes a hydrogen atom, a fluorine atom, a chlorine 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, 【Chemistry 2】 In equation (AIII), R １５ It contains single-bonded, substituted, or unsubstituted C1-C3 alkyl groups, The separator according to claim 5 or 6, wherein p is selected from a positive integer between 1 and 3, and n is selected from a positive integer between 1000 and 30000.

8. The liquid absorbent polymer further comprises an ether polymer, the ether polymer is formed into a sheet-like structure, and the sheet-like structure is subjected to (T ｍ２ A dynamic frequency scanning test was performed at +20°C to obtain the storage modulus G' - loss modulus G'' curve, and the slope of the storage modulus G' - loss modulus G'' curve was determined to be K １ Therefore, 1 < K １ <∞, T ｍ２ °C represents the melting temperature of the ether-based polymer, and selectively, 1 < K １ ≤ 100, and furthermore, selectively, 1 < K １ A separator according to any one of claims 1 to 7, wherein the value is ≤ 10.

9. The ether-based polymer comprises a structural unit represented by formula (BI) and / or a structural unit represented by formula (BII), 【Transformation 3】 In equation (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 It contains substituted or unsubstituted C1-C5 alkylene groups, 【Chemistry 4】 In equation (BII), R ２４ ~R ２７ Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R ２４ ~R ２７ The separator according to claim 8, wherein at least one of the members comprises a substituted or unsubstituted C1-C3 alkoxy group or ether group.

10. The liquid absorbent polymer includes an ester polymer, and the ester polymer is made into a sheet-like structure, and the sheet-like structure is (T ｍ３ A dynamic frequency scanning test was performed at +20°C to obtain the storage modulus G' - loss modulus G'' curve, and the slope of the storage modulus G' - loss modulus G'' curve was determined to be K ２ Therefore, 1 < K ２ <∞, T ｍ３ °C represents the melting temperature of the ester polymer, and selectively, 1 < K ２ ≤ 100, and furthermore, selectively, 1 < K ２ A separator according to any one of claims 1 to 9, wherein the value is ≤ 10.

11. The ester polymer comprises a structural unit represented by formula (CI) and / or a structural unit represented by formula (CII), 【Transformation 5】 In formula (CI), R ３１ , R ３２ and R ３３ Each independently contains a hydrogen atom, a substituted or unsubstituted C1-C8 alkyl group, and R ３４ It comprises a substituted or unsubstituted C1-C8 alkoxy group, or a substituted or unsubstituted C1-C8 hydroxyalkyl group. 【Transformation 6】 In equation (CII), R ３５ It contains substituted or unsubstituted C2-C6 methylene groups, and selectively, R ３５ The separator according to claim 10, wherein each comprises independently substituted or unsubstituted C2-C4 methylene groups.

12. The liquid absorbent polymer comprises an aldehyde-ketone polymer, and the aldehyde-ketone polymer is prepared into a sheet-like structure, and the sheet-like structure is treated with (T ｍ４ A dynamic frequency scanning test was performed at +20°C to obtain the storage modulus G' - loss modulus G'' curve, and the slope of the storage modulus G' - loss modulus G'' curve was determined to be K ３ Therefore, 0.8 ≤ K ３ <∞, T ｍ４ °C represents the melting temperature of the aldehyde-ketone polymer, and selectively, 0.8 ≤ K. ３ ≤ 100, and furthermore, selectively, 0.8 ≤ K ３ A separator according to any one of claims 1 to 11, wherein the value is ≤ 10.

13. The aldehyde-ketone polymer comprises a structural unit represented by formula (DI) and / or a structural unit represented by formula (DII), 【Transformation 7】 In equation (DI), R ４１ It contains single bonds, substituted or unsubstituted C1-C6 methylene groups, R ４２ It contains a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group, 【Transformation 8】 In equation (DII), R ４３ ~R ４６ The separator according to claim 12, wherein each of the elements independently comprises a hydrogen atom, a hydroxyl 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, and r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from positive integers.

14. The molecular weight of the aforementioned liquid absorbent polymer is 1.2 × 10⁻⁶. ５ g / mol~1.0×10 ６ A separator according to any one of claims 1 to 13, wherein the concentration is g / mol.

15. The separator according to any one of claims 1 to 14, wherein the separator body includes a substrate, and the polymer layer is installed on at least one surface of the substrate.

16. The separator according to any one of claims 1 to 14, wherein the separator body comprises a substrate and a heat-resistant coating layer, the heat-resistant coating layer is installed on at least one surface of the substrate, and the polymer layer is installed on a surface of the heat-resistant coating layer away from the substrate.

17. The polymer layer further contains heat-resistant particles, The separator according to any one of claims 1 to 16, wherein selectively, based on the total mass of the polymer layer, the ratio of the mass percentage of the liquid-retaining polymer to the mass percentage of the heat-resistant particles is (0.2 to 5):1, and selectively, (0.5 to 2):

1.

18. The separator according to any one of claims 1 to 17, wherein the thickness of the polymer layer is 0.5 μm to 3.0 μm, and selectively 1 μm to 2 μm.

19. A battery cell comprising the separator described in any one of claims 1 to 18.

20. A battery comprising the battery cell described in claim 19.

21. A power consumption device comprising the battery described in claim 20.

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