Separator, battery cell and electric device

Abstract

A separator, a battery cell and an electric device. The separator comprises a porous substrate and a coating provided on at least one side of the porous substrate. The coating comprises inorganic particles and polymer particles, and the glass transition temperature Tg of the polymer particles is 45°C-100°C. The separator is applied to a battery cell, so that the battery cell has good cycle performance.

Description

Separator membrane, battery cell and electrical device

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application 202411017001.7, filed on July 26, 2024, entitled “Separator, Battery Cell and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a separator, a battery cell, and an electrical device. Background Technology

[0004] After a battery cell is manufactured, the positive and negative electrode plates typically undergo a certain degree of volume expansion during charge-discharge cycles. As the electrode plates expand, the expansion force on the electrode assembly increases, leading to mutual compression of the electrode plates and the expulsion of electrolyte from the internal pores of the electrode plates, thus affecting the cycle performance of the battery cell. Furthermore, the expanding electrode assembly can also compress the outer packaging of the battery cell, causing deformation or even rupture, which in turn affects the reliability of the battery cell. Summary of the Invention

[0005] This disclosure provides a separator, a battery cell, and an electrical device. The separator, when applied to the battery cell, enables the battery cell to have good cycle performance.

[0006] This disclosure provides a separating membrane, the separating membrane comprising a porous substrate and a coating disposed on at least one side of the porous substrate, the coating comprising inorganic particles and polymer particles, wherein the glass transition temperature T of the polymer particles is... g The temperature range is 45℃-100℃.

[0007] The polymer particles have a glass transition temperature of 45℃-100℃. Polymer particles with this characteristic can improve the adhesion between the separator and the electrode sheets in the prepared electrode assembly, thereby preventing the electrode assembly from becoming loose. Furthermore, these polymer particles can form a stable gap between the positive and negative electrode sheets during charge-discharge cycles, effectively improving issues such as electrode sheet compression, electrolyte wetting, and deformation and breakage of the outer packaging. Therefore, the separator disclosed herein, when applied to a battery cell, can give the battery cell excellent cycle performance.

[0008] In some embodiments, the glass transition temperature T of the polymer particles g The temperature range is 70℃-100℃.

[0009] Glass transition temperature T of polymer particlesg Within the aforementioned range, the adhesion between the separator and the electrode sheet of the prepared electrode assembly can be improved, avoiding the problem of loosening of the prepared electrode assembly. It can also form a sufficient gap between the positive and negative electrode sheets during cyclic charging and discharging.

[0010] In some embodiments, the average particle size of the polymer particles is 8μm-30μm, and optionally 12μm-28μm.

[0011] The average particle size of the polymer particles is within the above range, which can form a sufficient gap between the positive and negative electrode plates during the charge and discharge cycle. This allows for better absorption of the volume expansion of the electrode plates, improving the problems of mutual compression of the electrode plates, electrolyte wetting of the electrode plates, and deformation and breakage of the outer packaging, thereby enabling the battery cell to have better cycle performance.

[0012] In some embodiments, the weight-average molecular weight of the polymer particles is 20,000-300,000, and optionally 80,000-280,000.

[0013] The polymer particles, with a weight-average molecular weight within the aforementioned range, can improve the adhesion between the separator and the electrode sheet in the prepared electrode assembly, preventing the electrode assembly from becoming loose. They can also form a stable and sufficient gap between the positive and negative electrode sheets during cyclic charging and discharging, thereby better absorbing the volume expansion of the electrode sheets and improving the problems of mutual compression of the electrode sheets, electrolyte wetting of the electrode sheets, and deformation and breakage of the outer packaging. This results in better cycle performance for the battery cell.

[0014] In some embodiments, the polymer particles comprise copolymers of at least two of the following: acrylate monomer units, olefinic acid monomer units, olefinic acid salt monomer units, olefinic nitrile monomer units, olefinic amide monomer units, styrene monomer units, and olefinic monomer units.

[0015] In some embodiments, the polymer particles comprise copolymers of acrylate monomer units and styrene monomer units, copolymers of acrylate monomer units and olefin unsaturated acid monomer units and styrene monomer units, copolymers of acrylate monomer units and olefin unsaturated amide monomer units and olefin unsaturated nitrile monomer units, copolymers of acrylate monomer units and olefin unsaturated acid monomer units and olefin unsaturated amide monomer units, copolymers of acrylate monomer units and olefin unsaturated acid monomer units and olefin unsaturated acid salt monomer units and olefin unsaturated amide monomer units, and propylene. Copolymers of ester monomer units - olefin unsaturated acid monomer units - olefin unsaturated amide monomer units - olefin unsaturated nitrile monomer units, acrylate monomer units - olefin unsaturated acid monomer units - olefin unsaturated acid salt monomer units - olefin unsaturated amide monomer units - olefin unsaturated nitrile monomer units, olefin unsaturated acid monomer units - styrene monomer units, styrene monomer units - olefin unsaturated nitrile monomer units, and styrene monomer units - olefin-based monomer units - olefin unsaturated nitrile monomer units.

[0016] In some embodiments, the acrylate monomer unit includes one or more of the following: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, and acetoxyethyl methacrylate.

[0017] In some embodiments, the olefinic unsaturated acid monomer unit includes one or more of acrylic acid, methacrylic acid, butenoic acid, and heptenoic acid.

[0018] In some embodiments, the olefinic unsaturated acid salt monomer unit includes one or more of lithium acrylate, lithium methacrylate, sodium acrylate, sodium methacrylate, ammonium acrylate, and ammonium methacrylate.

[0019] In some embodiments, the olefinic unsaturated nitrile monomer unit includes one or more of acrylonitrile, methacrylonitrile, and fumaronitrile.

[0020] In some embodiments, the olefinic unsaturated amide monomer unit includes one or more of acrylamide, N-hydroxymethylacrylamide, N-methylacrylamide, N-ethylacrylamide, N-butylacrylamide, 2-methylacrylamide, N-methoxymethylacrylamide, N-isopropoxymethylacrylamide, N-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N-octoxymethylacrylamide, and N-carboxymethoxymethylacrylamide.

[0021] In some embodiments, the olefin-based monomer unit includes one or more of butadiene, pentadiene, and isoprene.

[0022] In some embodiments, the polymer particles are embedded in the inorganic particles and form protrusions on the surface of the coating.

[0023] Optionally, the inorganic particles in the coating have a mass content of 55%-92%.

[0024] Optionally, the polymer particles in the coating comprise 5%-40% by mass.

[0025] Optionally, the inorganic particles include one or more of the following: inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0026] Optionally, the average particle size of the inorganic particles is 200nm-1000nm.

[0027] In some embodiments, the coating includes a heat-resistant layer and an adhesive layer, the adhesive layer being disposed on at least a portion of the surface of the heat-resistant layer or the porous substrate, the inorganic particles being disposed in the heat-resistant layer, and the polymer particles being disposed in the adhesive layer.

[0028] Optionally, the inorganic particles in the heat-resistant layer have a mass content of 50%-99%.

[0029] Optionally, the polymer particles in the adhesive layer comprise 80%-95% by mass.

[0030] Optionally, the inorganic particles include one or more of the following: inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0031] Optionally, the average particle size of the inorganic particles is 200nm-1000nm.

[0032] In some embodiments, the heat-resistant layer further includes a fibrous material. Optionally, the fibrous material includes nanocellulose.

[0033] In some embodiments, the average diameter of the fibrous material is 10 nm to 40 nm.

[0034] In some embodiments, the average length of the fibrous material is 100 nm to 600 nm.

[0035] In some embodiments, the aspect ratio of the fibrous material is 5-50.

[0036] In some embodiments, the fibrous material in the heat-resistant layer has a mass content of 5%-25%.

[0037] In some embodiments, the inorganic particles include first inorganic particles, which are aggregates of a plurality of primary particles.

[0038] In some embodiments, the average particle size of the primary particles constituting the aggregate is 10 nm to 50 nm.

[0039] In some embodiments, the mass content of the first inorganic particles in the heat-resistant layer is greater than or equal to 55%.

[0040] In some embodiments, the first inorganic particles include one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

[0041] In some embodiments, the inorganic particles include not only the first inorganic particles but also a second inorganic particle, and the average particle size of the second inorganic particle is greater than the average particle size of the primary particles constituting the aggregate.

[0042] In some embodiments, the second inorganic particle has a primary particle morphology.

[0043] In some embodiments, the average particle size of the second inorganic particles is 200 nm to 500 nm.

[0044] In some embodiments, the mass content of the second inorganic particles in the heat-resistant layer is 5%-30%.

[0045] In some embodiments, the second inorganic particle includes one or more of the following: inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0046] In some embodiments, the thickness of the coating is 0.5 μm-5 μm.

[0047] In some embodiments, the porous substrate is made of polyolefin.

[0048] In some embodiments, the compressive modulus of the separator is greater than or equal to 240 MPa, and can be selected as 245 MPa-350 MPa.

[0049] The second aspect of this disclosure provides a battery cell, including a positive electrode, a negative electrode, and a separator as described in the first aspect.

[0050] In some embodiments, the porous substrate has a coating on at least the side facing the positive electrode sheet.

[0051] A second aspect of this disclosure provides an electrical device that includes a battery cell according to the second aspect of this disclosure.

[0052] The electrical device disclosed herein includes the battery cell provided herein and thus has at least the same advantages as the battery cell. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0054] Figure 1 shows a schematic diagram of a battery cell provided in some embodiments of this disclosure.

[0055] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this disclosure. Detailed Implementation

[0056] Hereinafter, embodiments of the separator, battery cell, and power supply device of this disclosure are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0057] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0059] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0060] Unless otherwise specified, all steps in this disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0061] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0062] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0063] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] Unless otherwise stated, the terms used in this disclosure have the common meanings as commonly understood by those skilled in the art.

[0065] Unless otherwise stated, the values ​​of the parameters mentioned in this disclosure can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this disclosure. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0066] The battery device mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0067] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0068] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more battery cell assemblies housed within the housing. As an example, the battery cell assembly may be a battery module, which can be housed within the housing by securing the battery module to the housing. Alternatively, the battery cell assembly may be housed within the housing by directly securing multiple battery cells to the housing.

[0069] A battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, and the embodiments disclosed herein are not limited to this. Figure 1 shows a cuboid battery cell 5 as an example.

[0070] A single battery cell includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a stacked structure, and the embodiments disclosed herein are not limited to this.

[0071] The battery cell also includes an outer packaging, which encapsulates the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0072] The battery cells provided in the embodiments of this disclosure may include, but are not limited to, lithium battery cells, sodium battery cells, etc.

[0073] It is understandable that electrode assemblies are formed by bonding positive electrode sheets, negative electrode sheets, and a separator. Electrode assemblies possess a certain degree of rigidity; that is, because the bonded electrode sheets and separator support each other, they form a structure of a certain thickness, and a structure of a certain thickness possesses a certain rigidity. If the adhesion between the electrode sheets and the separator is weak, a large gap will form between the electrode sheets and the separator in the prepared electrode assembly. In this case, the electrode sheets and separator cannot adhere to each other and support each other, resulting in a loose electrode assembly with reduced rigidity, and consequently, a deterioration in the performance of the battery cell. Furthermore, after the battery cell is manufactured, the positive and negative electrode sheets typically undergo a certain volume expansion during charge-discharge cycles. As the electrode sheets expand, the expansion force on the electrode assembly increases, which can lead to the electrode sheets squeezing against each other and causing the electrolyte in the internal pores of the electrode sheets to be squeezed out, thus affecting the cycle performance of the battery cell. In addition, the expanding electrode assembly can also squeeze the outer packaging of the battery cell, causing deformation or even rupture of the outer packaging, thereby affecting the reliability of the battery cell.

[0074] Currently, larger polymer particles are typically incorporated into the coating of the separator. These polymer particles act as a bond between the separator and the electrode sheets, improving their adhesion and preventing the electrode assembly from becoming loose. Furthermore, using larger polymer particles in the separator helps to create a gap between the positive and negative electrode sheets during charge-discharge cycles. However, a challenge exists in battery cells: achieving optimal adhesion between the separator and the electrode sheets in the electrode assembly and maintaining the appropriate gap size between the positive and negative electrode sheets during charge-discharge cycles cannot be simultaneously achieved.

[0075] Currently, the polymer particles in the separator coating are mainly polyvinylidene fluoride (PVDF) particles. PVDF particles have a low glass transition temperature, which can bond the electrode sheets to the separator and prevent the prepared electrode assembly from becoming loose. However, PVDF particles have poor extrusion resistance, thus failing to form a sufficient gap between the positive and negative electrode sheets during the cycle charging and discharging of the battery cell. Insufficient gap size between the positive and negative electrode sheets cannot effectively improve the problems of mutual extrusion of the electrode sheets, electrolyte wetting of the electrode sheets, and deformation and breakage of the outer packaging.

[0076] Based on this, the present disclosure provides a separator that is applied to a battery cell, which can enable the separator of the prepared electrode assembly to have good adhesion to the electrode sheet, and can also form a stable gap between the positive electrode sheet and the negative electrode sheet during cyclic charging and discharging, thereby enabling the battery cell to have good cycle performance.

[0077] The separator disclosed herein includes a porous substrate and a coating disposed on at least one side of the porous substrate. The coating includes inorganic particles and polymer particles, wherein the glass transition temperature T of the polymer particles is... g The temperature range is 45℃-100℃.

[0078] The polymer particles have a glass transition temperature of 45℃-100℃. Polymer particles with this characteristic can improve the adhesion between the separator and the electrode sheets in the prepared electrode assembly, thereby preventing the electrode assembly from becoming loose. Furthermore, these polymer particles can form a stable gap between the positive and negative electrode sheets during charge-discharge cycles, effectively improving issues such as electrode sheet compression, electrolyte wetting, and deformation and breakage of the outer packaging. Therefore, the separator disclosed herein, when applied to a battery cell, can give the battery cell excellent cycle performance.

[0079] Glass transition temperature T of polymer particles g The temperature range is 45℃-100℃, for example, it can be 45℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 95℃, 98℃, 100℃, or any combination of the above values.

[0080] Optionally, the glass transition temperature T of the polymer particles gThe temperature ranges are 60℃-100℃, 62℃-100℃, 64℃-100℃, 66℃-100℃, 68℃-100℃, 70℃-100℃, 72℃-100℃, 74℃-100℃, 76℃-100℃, 60℃-98℃, 62℃-98℃, 64℃-98℃, 66℃-98℃, 68℃-98℃, 70℃-98℃, 72℃-98℃, 74℃-98℃, and 76℃-98℃.

[0081] Glass transition temperature T of polymer particles g Within the aforementioned range, the adhesion between the separator and the electrode sheet of the prepared electrode assembly can be improved, avoiding the problem of loosening of the prepared electrode assembly. It can also form a sufficient gap between the positive and negative electrode sheets during cyclic charging and discharging.

[0082] Glass transition temperature T of polymer particles g The test can be performed as follows: Take an appropriate amount of sample (e.g., 5mg-10mg) and place it in the crucible of the differential scanning calorimeter (DSC), level it, and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. The glass transition temperature T of the polymer particles is obtained from the DSC curve. g .

[0083] In some embodiments, the average particle size of the polymer particles can be 8μm-30μm, for example, it can be 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, or any range of the above values.

[0084] Optionally, the average particle size of the polymer particles can be 10μm-28μm, 12μm-28μm, 14μm-28μm, 10μm-26μm, 12μm-26μm, 14μm-26μm, 10μm-24μm, 12μm-24μm, or 14μm-24μm.

[0085] The average particle size of the polymer particles is within the above range, which can form a sufficient gap between the positive and negative electrode plates during the charge and discharge cycle. This allows for better absorption of the volume expansion of the electrode plates, improving the problems of mutual compression of the electrode plates, electrolyte wetting of the electrode plates, and deformation and breakage of the outer packaging, thereby enabling the battery cell to have better cycle performance.

[0086] In the context of this disclosure, the average particle size can be tested as follows: Using a scanning electron microscope (SEM) according to JY / T010-1996, acquire an SEM image of the separator. Randomly select a test sample with dimensions of 50mm x 100mm on the separator. Randomly select multiple test areas (e.g., 5) within the test sample, and read the particle size of each particle in each test area at a certain magnification (e.g., 500x or higher). Count the number and particle size values ​​of particles in each test area, and take the arithmetic mean of the particle sizes in all test areas as the average particle size. To ensure the accuracy of the test results, multiple test samples (e.g., 10) can be used for the above test, and the average value of each test sample can be taken as the final test result. The testing instrument can be a ZEISS Sigma 300. It should be noted that when the particle is irregularly shaped, the distance between the two farthest points on the particle is taken as the particle size.

[0087] In some embodiments, the weight-average molecular weight of the polymer particles can be 20,000 to 300,000, for example, it can be 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, or any combination of the above values.

[0088] Optionally, the weight-average molecular weight of the polymer particles can be 40,000-280,000, 60,000-280,000, 80,000-280,000, 100,000-280,000, 40,000-240,000, 60,000-240,000, 80,000-240,000, or 100,000-240,000.

[0089] The polymer particles, with a weight-average molecular weight within the aforementioned range, can improve the adhesion between the separator and the electrode sheet in the prepared electrode assembly, preventing the electrode assembly from becoming loose. They can also form a stable and sufficient gap between the positive and negative electrode sheets during cyclic charging and discharging, thereby better absorbing the volume expansion of the electrode sheets and improving the problems of mutual compression of the electrode sheets, electrolyte wetting of the electrode sheets, and deformation and breakage of the outer packaging. This results in better cycle performance for the battery cell.

[0090] The weight-average molecular weight of polymer particles can be tested by gel permeation chromatography. The testing standard can be found in GB / T 21863-2008.

[0091] In some embodiments, the polymer particles may include copolymers of at least two of the following: acrylate monomer units, olefinic acid monomer units, olefinic acid salt monomer units, olefinic nitrile monomer units, olefinic amide monomer units, styrene monomer units, and olefinic monomer units.

[0092] In some embodiments, the polymer particles may include copolymers of acrylate monomer units and styrene monomer units, copolymers of acrylate monomer units and olefinic unsaturated acid monomer units and styrene monomer units, copolymers of acrylate monomer units and olefinic unsaturated amide monomer units and olefinic unsaturated nitrile monomer units, copolymers of acrylate monomer units and olefinic unsaturated acid monomer units and olefinic unsaturated amide monomer units, copolymers of acrylate monomer units and olefinic unsaturated acid monomer units and olefinic unsaturated acid salt monomer units and olefinic unsaturated amide monomer units, and propylene. Copolymers of ester monomer units - olefin unsaturated acid monomer units - olefin unsaturated amide monomer units - olefin unsaturated nitrile monomer units, acrylate monomer units - olefin unsaturated acid monomer units - olefin unsaturated acid salt monomer units - olefin unsaturated amide monomer units - olefin unsaturated nitrile monomer units, olefin unsaturated acid monomer units - styrene monomer units, styrene monomer units - olefin unsaturated nitrile monomer units, and styrene monomer units - olefin-based monomer units - olefin unsaturated nitrile monomer units.

[0093] In some embodiments, the polymer particles include at least acrylate monomer units.

[0094] In some embodiments, the acrylate monomer unit may include one or more of the following: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, and acetoxyethyl methacrylate.

[0095] In some embodiments, the olefinic unsaturated acid monomer unit may include one or more of acrylic acid, methacrylic acid, butenoic acid, and heptenoic acid.

[0096] In some embodiments, the olefinic unsaturated acid salt monomer unit may include one or more of lithium acrylate, lithium methacrylate, sodium acrylate, sodium methacrylate, ammonium acrylate, and ammonium methacrylate.

[0097] In some embodiments, the olefinic unsaturated nitrile monomer unit may include one or more of acrylonitrile, methacrylonitrile, and fumaric acid.

[0098] In some embodiments, the olefinic unsaturated amide monomer unit may include one or more of acrylamide, N-hydroxymethylacrylamide, N-methylacrylamide, N-ethylacrylamide, N-butylacrylamide, 2-methylacrylamide, N-methoxymethylacrylamide, N-isopropoxymethylacrylamide, N-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N-octoxymethylacrylamide, and N-carboxymethoxymethylacrylamide.

[0099] In some embodiments, the olefin-based monomer unit may include one or more of butadiene, pentadiene, and isoprene.

[0100] In some embodiments, polymer particles may be embedded within inorganic particles and form protrusions on the surface of the coating.

[0101] Optionally, the mass content of inorganic particles in the coating can be 55%-92%.

[0102] Optionally, the inorganic particles may include one or more of the following: inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0103] Optionally, the inorganic particles may have a primary particle morphology.

[0104] Optionally, the average particle size of the inorganic particles can be 200nm-1000nm, specifically 200nm-800nm, 200nm-600nm, 200nm-500nm, 220nm-800nm, 220nm-600nm, or 220nm-500nm.

[0105] Optionally, the polymer particles may constitute 5%-40% of the coating by mass.

[0106] The coating also includes an adhesive. Optionally, the adhesive may constitute 0.5% to 8% of the coating by mass.

[0107] The adhesive is a non-particulate adhesive. Optionally, the adhesive may include homopolymers or copolymers selected from the following monomers: allyl polyether sulfate, acrylic acid, methacrylic acid, acrylamide, methyl methacrylate, butyl acrylate, ethyl acrylate, glycidyl methacrylate, vinyl alcohol, acrylonitrile, hydroxyethyl acrylate, styrene, acetoxyethyl methacrylate, vinyltrimethoxysilane, lithium acrylate, lithium methacrylate. More preferably, the adhesive may include at least one of the following: polyacrylic acid, polymethyl methacrylate, polyacrylonitrile, polyacrylamide, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polystyrene-co-methyl methacrylate, polystyrene-co-butyl acrylate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide.

[0108] Optionally, the coating may also include a dispersant. The dispersant may be one or more of the following, including but not limited to sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, and ammonium polyacrylate.

[0109] In other embodiments, the coating may include a heat-resistant layer and an adhesive layer, the adhesive layer being disposed on at least a portion of the surface of the heat-resistant layer or the porous substrate, inorganic particles being disposed in the heat-resistant layer, and polymer particles being disposed in the adhesive layer.

[0110] Optionally, the mass content of inorganic particles in the heat-resistant layer can be 50%-99%. More alternatively, the mass content of inorganic particles in the heat-resistant layer can be 65%-99%, 80%-99%, 85%-99%, 50%-97%, 65%-97%, 80%-97%, or 85%-97%.

[0111] Optionally, the inorganic particles may include, but are not limited to, one or more of the following: inorganic particles having a dielectric constant of 5 or higher, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0112] Optionally, the inorganic particles may have a primary particle morphology.

[0113] Optionally, the average particle size of the inorganic particles can be 200nm-1000nm, specifically 200nm-800nm, 200nm-600nm, 200nm-500nm, 220nm-800nm, 220nm-600nm, or 220nm-500nm.

[0114] Optionally, the mass content of polymer particles in the adhesive layer can be 80%-95%.

[0115] The heat-resistant layer also contains a first adhesive, and the adhesive layer also contains a second adhesive.

[0116] The first and second adhesives are non-particulate adhesives. Optionally, the first and second adhesives may independently comprise homopolymers or copolymers selected from the following monomers: allyl polyether sulfate, acrylic acid, methacrylic acid, acrylamide, methyl methacrylate, butyl acrylate, ethyl acrylate, glycidyl methacrylate, vinyl alcohol, acrylonitrile, hydroxyethyl acrylate, styrene, acetoxyethyl methacrylate, vinyltrimethoxysilane, lithium acrylate, and lithium methacrylate. Alternatively, the first adhesive and the second adhesive may independently include at least one of the following: polyacrylic acid, polymethyl methacrylate, polyacrylonitrile, polyacrylamide, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polystyrene-co-methyl methacrylate, polystyrene-co-butyl acrylate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, and polyimide.

[0117] Optionally, the heat-resistant layer may also contain a dispersant. The dispersant may be one or more of the following, including but not limited to sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, and ammonium polyacrylate.

[0118] Optionally, the adhesive layer may also contain a dispersant. The dispersant may be one or more of the following, including but not limited to sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, and ammonium polyacrylate.

[0119] Optionally, the heat-resistant layer may also contain wetting agents and / or surfactants, etc.

[0120] In some embodiments, the heat-resistant layer may also include a fibrous material.

[0121] Alternatively, the fibrous material may include nanocellulose.

[0122] Nanocellulose possesses both the properties of cellulose and the properties of nanoparticles. In the heat-resistant layer of the insulating membrane, nanocellulose exists in a fibrous form.

[0123] Nanocellulose has good heat resistance and small volume change after heating, which can improve the heat resistance of the separator. At the same time, nanocellulose has a low density, which can reduce the mass of the battery cell and increase the energy density of the battery cell.

[0124] In some embodiments, nanocellulose may include one or more of cellulose nanofibrils (CNF, also known as nanofibrillated cellulose or microfibrillated cellulose) and cellulose nanocrystals (CNC, also known as cellulose nanocrystals or nanocrystalline cellulose). Optionally, nanocellulose may include cellulose nanocrystals, which have the advantage of high crystallinity, thereby better improving the heat resistance of the separator.

[0125] In some embodiments, nanocellulose may include unmodified nanocellulose (also known as hydroxyl nanocellulose) and / or modified nanocellulose. Modified nanocellulose includes hydroxyl groups and modified groups. In some embodiments, the modified groups may include one or more of amino, carboxyl, aldehyde, sulfonic acid, boric acid, and phosphate groups, optionally including one or more of sulfonic acid, boric acid, and phosphate groups. When nanocellulose has the above-mentioned specific modified groups, it can improve the heat resistance of the separator and enhance the thermal safety performance of the battery cell; on the other hand, it can also improve the bonding strength between the heat-resistant layer and the porous substrate. In addition, the presence of modified groups can reduce the proportion of hydroxyl groups, which is beneficial for the heat-resistant layer slurry to have a suitable viscosity, and is more conducive to the coating of the heat-resistant layer slurry, thereby improving the production efficiency of the separator and the uniformity of the heat-resistant layer. The types of modified groups in nanocellulose can be determined by infrared spectroscopy. The testing standard can refer to GB / T 6040-2019.

[0126] Optionally, the molar ratio of the modified group to the hydroxyl group can be from 1:4 to 4:1, or from 2:3 to 7:3. This can further improve the heat resistance, ion transport characteristics, and electrolyte wetting and retention properties of the separator.

[0127] In some embodiments, the average diameter of the fibrous material can be 10nm-40nm, and optionally 15nm-35nm.

[0128] In some embodiments, the average length of the fibrous material can be 100nm-600nm, and optionally 200nm-500nm.

[0129] The average length and average diameter of the fibrous material can be determined using the following method: A 3.6 mm × 3.6 mm sample is cut from a randomly selected area of ​​the separator. The microstructure of the heat-resistant layer in the sample is mapped using a scanning electron microscope (SEM). A high-vacuum mode is selected, with a working voltage of 3 kV and a magnification of 30,000x to obtain an SEM image. Based on the obtained SEM image, multiple (e.g., more than 5) test areas are selected for length statistics. Each test area has a size of 0.5 μm × 0.5 μm. The average length of each test area is then taken as the average length of the fibrous material. Based on the obtained SEM image, multiple (e.g., more than 5) test areas are selected for diameter statistics using Nano Measurer particle size distribution statistical software. Each test area has a size of 0.5 μm × 0.5 μm. The average diameter of each test area is then taken as the average diameter of the fibrous material. The testing instrument can be a ZEISS Sigma300.

[0130] In some embodiments, the aspect ratio of the fibrous material can be 5-50, preferably 10-30.

[0131] In some embodiments, the mass content of fibrous material in the heat-resistant layer can be 5%-25%.

[0132] In some embodiments, inorganic particles and fibrous materials are disposed in the heat-resistant layer, and the inorganic particles may include first inorganic particles, which are aggregates of multiple primary particles.

[0133] In some embodiments, the average particle size of the primary particles constituting the aggregate can be 10nm-50nm, for example, 10nm-49nm, 15nm-49nm, 20nm-49nm, 25nm-49nm, 10nm-45nm, 15nm-45nm, 20nm-45nm, or 25nm-45nm.

[0134] In some embodiments, the mass content of the first inorganic particles in the heat-resistant layer may be greater than or equal to 55%.

[0135] In some embodiments, the first inorganic particles may include one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

[0136] In some embodiments, inorganic particles and fibrous materials are disposed in the heat-resistant layer, and the inorganic particles may simultaneously include first inorganic particles and second inorganic particles, and the average particle size of the second inorganic particles is greater than the average particle size of the primary particles constituting the aggregate.

[0137] In some embodiments, the second inorganic particles have a primary particle morphology.

[0138] In the heat-resistant layer of the isolation membrane, the first inorganic particles exhibit an aggregate morphology. In contrast, the second inorganic particles are dispersed in the heat-resistant layer and do not exhibit an aggregate morphology. This allows for the distinction between the first and second inorganic particles in the heat-resistant layer.

[0139] In some embodiments, the average particle size of the second inorganic particles can be from 200 nm to 500 nm, and optionally from 220 nm to 460 nm.

[0140] In some embodiments, the mass content of the second inorganic particles in the heat-resistant layer can be 5%-30%.

[0141] In some embodiments, the second inorganic particle may include one or more of the following: inorganic particles having a dielectric constant of 5 or greater, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of undergoing electrochemical reactions.

[0142] In the context of this disclosure, optionally, inorganic particles having a dielectric constant of 5 or higher may include boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxides, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, aluminum hydroxide, barium oxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, calcium fluoride, barium fluoride, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, 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), Pb (Mg3Nb) 2 / 3 The inorganic particles can be selected from one or more of PbTiO3 (PMN-PT) and their respective modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification.

[0143] In the context of this disclosure, optionally, inorganic particles that are ion-conductive but do not store ions may include Li3PO4, lithium titanium phosphate, or other similar materials. x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 O y3 Type glass, lithium lanthanum titanate (Li) x4 Lay4 TiO3, lithium germanium thiophosphate Li x5 Ge y5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4 One or more of the following are given: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can further improve the ion conductivity of the separator.

[0144] In the context of this disclosure, the inorganic particles capable of undergoing electrochemical reactions may optionally include one or more of lithium-containing transition metal oxides, lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium-titanium compounds.

[0145] In some embodiments, the coating thickness can be 0.5 μm to 5 μm. In this disclosure, the coating thickness refers to the thickness of the portion of the coating without protruding polymer particles.

[0146] In some embodiments, the porous substrate may be made of polyolefins, such as polyethylene and / or polypropylene. Optionally, the porous substrate may be a porous polyethylene membrane.

[0147] In some embodiments, the thickness of the porous substrate can be 4μm-12μm, and optionally 4μm-9μm.

[0148] In some embodiments, the porosity of the porous substrate can be 25%-60%, optionally 28%-50%.

[0149] In some embodiments, the thickness of the separator can be 6μm-18μm. This is beneficial for improving the energy density of the battery cell.

[0150] In some embodiments, the compressive modulus of the separator can be greater than or equal to 240 MPa. Optionally, the compressive modulus of the separator can be between 245 MPa and 350 MPa.

[0151] The compressive modulus of the separator can be tested using the following method.

[0152] Step 1: Sample pretreatment: (1) Use a die to punch the release film. Stacking order: die / white paper / release film / white paper / pressing block. Punch 5 layers at a time. 100 layers are a group. Make 3 groups of parallel samples. Sample size is 60mm*70mm. (2) Use a guillotine cutter to punch the aluminum-plastic film with a size of 90mm*200mm. (3) Fold the aluminum-plastic film along the length. Fix the center of the four sides of the punched release film sample with green glue and place it in an aluminum-plastic film packaging bag (Pocket). (4) Use a top-side sealing machine to seal the two long sides of the sample. Then vacuum seal the top. The sealing machine is heated to 185℃. (5) Place a pad in the center of the sealed sample and mark the frame. (6) Measure the thickness of the release film within the marked position with a micrometer. 4 points on the long side and 3 points on the short side.

[0153] Step 2: Sample testing: (1) Turn on the in-situ expansion testing system IEST SWE2110 (Yuaneng Technology Co., Ltd.), open the operating software MISS, pressure calibration; select compression test (transient), thickness calibration; (2) Place the sample in the upper and lower clamps, move the upper clamp to ensure that the upper clamp is in the position marked on the sample frame; (3) Click the MISS software to start the experiment. After the test is completed, measure the sample thickness M1; mark the clamp indentation positions on the upper and lower sides of the sample with a marker; (4) Repeat steps 2-3 and test again.

[0154] Step 3: Data processing: (1) Stress = Pressure * 10 / Fixture area; Deformation = Initial thickness M1 - Real-time thickness; Strain = Deformation / Initial thickness; (2) Plot the stress-strain curve with strain as the abscissa and stress as the ordinate; Linear fitting of the stress / strain curve from 3MPa to 5MPa yields the compressive modulus of the isolation membrane.

[0155] It should be noted that the coating parameters of the above-mentioned separator are all coating parameters for one side of the porous substrate. When the coating is applied to both sides of the porous substrate, if the coating parameters on either side meet the requirements of this disclosure, it is considered to fall within the protection scope of this disclosure.

[0156] This disclosure also provides a method for preparing the above-mentioned separator membrane.

[0157] The method for preparing the separator membrane includes the following steps: providing a porous substrate; providing a slurry comprising inorganic particles, polymer particles, and a binder; coating the slurry onto at least one surface of the porous substrate, drying it to form a coating, and obtaining the separator membrane. The polymer particles are embedded in the inorganic particles and form protrusions on the surface of the coating.

[0158] In some embodiments, the solvent for the slurry may be water, such as deionized water.

[0159] In some embodiments, the slurry may also include other components, such as dispersants.

[0160] The raw materials and their content parameters used in the preparation method of the separator membrane can be referred to the separator membrane mentioned above, and will not be repeated here.

[0161] Unless otherwise specified, all raw materials used in the preparation of the separator membrane can be obtained commercially.

[0162] This disclosure also provides another method for preparing the above-described separator.

[0163] The method for preparing the separator includes the following steps: providing a porous substrate; providing a heat-resistant layer slurry comprising inorganic particles and a first binder, and an adhesive layer slurry comprising polymer particles and a second binder; coating the heat-resistant layer slurry onto at least one surface of the porous substrate, and drying it to form a heat-resistant layer; coating the adhesive layer slurry onto at least a portion of the surface of the heat-resistant layer or the porous substrate, and drying it to form an adhesive layer, thereby obtaining the separator. The separator coating comprises a heat-resistant layer and an adhesive layer, the adhesive layer being disposed on at least a portion of the surface of the heat-resistant layer or the porous substrate, the inorganic particles being disposed in the heat-resistant layer, and the polymer particles being disposed in the adhesive layer.

[0164] In some embodiments, the solvent for the heat-resistant layer slurry and the adhesive layer slurry may be water, such as deionized water.

[0165] In some embodiments, the heat-resistant slurry further includes fibrous materials.

[0166] In some embodiments, the heat-resistant slurry may also include other components, such as dispersants.

[0167] In some embodiments, the adhesive layer slurry may also include other components, such as dispersants, wetting agents, surfactants, etc.

[0168] The raw materials and their content parameters used in the preparation method of the separator membrane can be referred to the separator membrane mentioned above, and will not be repeated here.

[0169] Unless otherwise specified, all raw materials used in the preparation of the separator membrane can be obtained commercially.

[0170] This disclosure also provides a battery cell that includes the aforementioned separator.

[0171] A single battery cell also includes a positive electrode, a negative electrode, and an electrolyte. The composition of the positive electrode, negative electrode, and electrolyte varies depending on the type of battery cell.

[0172] Optionally, the porous substrate of the separator has a coating on at least one side facing the positive electrode.

[0173] In some embodiments, the positive electrode may include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0174] Taking a lithium-ion battery cell as an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. In some embodiments, to further improve the energy density of the battery cell, the positive electrode active material may include materials with the general formula Li a Ni b Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes but is not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes but is not limited to one or more of N, F, S and Cl.

[0175] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.1 Al 0.05One or more of O2, LiFePO4, and LiMnPO4.

[0176] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar O content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Oxygen release from the crystal lattice causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0177] Taking sodium-ion battery cells as an example, the positive electrode active material may include, but is not limited to, one or more of the following: sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials. As an example, the positive electrode active material may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In this case, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes, but is not limited to, H. + Li + Na + K + and NH4 + One or more of the following, M' is a transition metal cation, optionally including but not limited to one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally one or more of F, Cl and Br.

[0178] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0179] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0180] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0181] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. Examples of the metal material include, but are not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of the polymer substrate include, but are not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0182] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0183] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0184] The negative electrode active material may be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include, but are not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include, but are not limited to, one or more of elemental tin, tin oxide, and tin alloys.

[0185] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0186] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0187] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0188] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0189] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0190] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet of this disclosure also includes a protective layer covering the surface of the negative electrode film layer.

[0191] The electrolyte acts as a conductor of ions between the positive and negative electrodes. In some embodiments, the electrolyte may include an electrolyte salt and a solvent.

[0192] Taking a lithium battery cell as an example, the electrolyte salt may include, but is not limited to, one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0193] Taking sodium battery cells as an example, the electrolyte salt may include, but is not limited to, one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium difluorosulfonylimide (NaFSI), sodium difluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0194] In some embodiments, the solvent may include, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0195] In some embodiments, the electrolyte may also include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature performance, etc.

[0196] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained.

[0197] This disclosure also provides an electrical device, which includes the battery device provided in this disclosure. The battery device can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0198] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0199] Figure 2 is a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used as the power source.

[0200] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0201] Example

[0202] The following examples describe the contents of this disclosure in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0203] Example 1

[0204] Preparation of positive electrode sheet

[0205] LiNi, the positive electrode active material 0.5 Co 0.2 Mn 0.3O2, acetylene black (positive electrode conductive agent), and polyvinylidene fluoride (PVDF) (positive electrode binder) are mixed in a mass ratio of 94:3:3. An appropriate amount of N-methylpyrrolidone (NMP) solvent is added, and the mixture is stirred until homogeneous to obtain a positive electrode slurry. The positive electrode slurry is coated onto both surfaces of the positive electrode current collector aluminum foil. After drying, cold pressing, and slitting, the positive electrode sheet is obtained.

[0206] Preparation of negative electrode sheet

[0207] Artificial graphite (anode active material), acetylene black (anode conductive agent), styrene-butadiene rubber (SBR) (anode binder), and sodium carboxymethyl cellulose (sodium carboxymethyl cellulose) were mixed evenly in an appropriate amount of deionized water at a mass ratio of 95:2:2:1 to obtain a cathode slurry. The cathode slurry was coated onto copper foil (anode current collector), and after drying, cold pressing, and slitting, a cathode sheet was obtained.

[0208] Preparation of the separating membrane

[0209] According to the mass ratio of 10:50:20:20, tert-butyl acrylate monomer, N-hydroxymethylacrylamide monomer, acrylonitrile monomer and acrylic acid monomer were weighed and mixed evenly, and then polymer particle emulsion was obtained by emulsion polymerization.

[0210] Commercially available polyethylene microporous film with a thickness of 7μm was used as the porous substrate.

[0211] Preparation of heat-resistant slurry: Inorganic alumina particles, binder polyacrylic acid, and dispersant sodium carboxymethyl cellulose are mixed evenly in deionized water at a solid content mass ratio of 92:5:3 to obtain the heat-resistant slurry.

[0212] Preparation of adhesive layer slurry: The polymer particle emulsion obtained above, the binder polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose, and the ether-based surfactant are stirred evenly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain the adhesive layer slurry.

[0213] The prepared heat-resistant slurry is applied to both surfaces of a porous substrate using a micro-gravure method. After drying, the adhesive slurry is sprayed onto the heat-resistant layer. Then, through drying and slitting processes, a release film is obtained.

[0214] In the obtained isolation membrane, the inorganic particles in the heat-resistant layer have a primary particle morphology with an average particle size of 400 nm; the polymer particles in the adhesive layer have an average particle size of 18 μm and a glass transition temperature T0. g The temperature is 82℃.

[0215] Preparation of electrolyte

[0216] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 3:7 to obtain a solvent. Fully dried LiPF6 was dissolved in the above solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0217] Preparation of battery cells

[0218] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain an electrode assembly. The electrode assembly is placed in a hard outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a battery cell is obtained.

[0219] Example 2

[0220] Except for the difference in the preparation process of the separator, the preparation process of the battery cell is the same as that in Example 1.

[0221] Preparation of the separating membrane

[0222] According to the mass ratio of 10:50:20:20, tert-butyl acrylate monomer, N-hydroxymethylacrylamide monomer, acrylonitrile monomer and acrylic acid monomer were weighed and mixed evenly, and then polymer particle emulsion was obtained by emulsion polymerization.

[0223] Commercially available polyethylene microporous film with a thickness of 7μm was used as the porous substrate.

[0224] Preparation of the heat-resistant layer slurry: Nanocellulose, first inorganic alumina particles, second inorganic alumina particles, and polyacrylic acid were mixed evenly in deionized water at a solid content mass ratio of 20:60:18:2 to obtain the heat-resistant layer slurry. The nanocellulose had an average length of 400 nm and an average diameter of 25 nm.

[0225] Preparation of adhesive layer slurry: The polymer particle emulsion obtained above, the binder polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose, and the ether-based surfactant are stirred evenly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain the adhesive layer slurry.

[0226] The prepared heat-resistant slurry is applied to both surfaces of a porous substrate using a micro-gravure method. After drying, the adhesive slurry is sprayed onto the heat-resistant layer. Then, through drying and slitting processes, a release film is obtained.

[0227] In the obtained separator, the first inorganic alumina particles are an aggregate of multiple primary particles, with an average particle size of 25 nm; the second inorganic alumina particles have a primary particle morphology with an average particle size of 400 nm; the polymer particles in the adhesive layer have an average particle size of 18 μm and a glass transition temperature T0. g The temperature is 82℃.

[0228] Comparative Example 1

[0229] Except for the following differences, the manufacturing process of the battery cells is the same as that in Example 1.

[0230] Preparation of adhesive layer slurry: Mix commercially available polyvinylidene fluoride granules, polymethyl methacrylate binder, sodium carboxymethyl cellulose dispersant, and ether-based surfactant in deionized water at a solid content mass ratio of 87:8:3:2 to obtain adhesive layer slurry.

[0231] In the obtained isolation membrane, the inorganic particles in the heat-resistant layer have a primary particle morphology with an average particle size of 400 nm; the polyvinylidene fluoride particles in the adhesive layer have an average particle size of 18 μm and a glass transition temperature T0. g The temperature is -40℃.

[0232] Comparative Example 2

[0233] Except for the following differences, the manufacturing process of the battery cells is the same as in Example 2.

[0234] Preparation of adhesive layer slurry: Mix commercially available polyvinylidene fluoride granules, polymethyl methacrylate binder, sodium carboxymethyl cellulose dispersant, and ether-based surfactant in deionized water at a solid content mass ratio of 87:8:3:2 to obtain adhesive layer slurry.

[0235] In the obtained separator, the first inorganic alumina particles are an aggregate of multiple primary particles, with an average particle size of 25 nm; the second inorganic alumina particles have a primary particle morphology with an average particle size of 400 nm; the polyvinylidene fluoride particles in the adhesive layer have an average particle size of 18 μm and a glass transition temperature T0. g The temperature is -40℃.

[0236] Performance testing

[0237] (1) Average particle size test

[0238] The average particle size of the inorganic particles, the first inorganic particles, and the second inorganic particles in the heat-resistant layer was tested according to the following method:

[0239] Using a scanning electron microscope (SEM) according to JY / T010-1996, SEM images of a porous substrate with a heat-resistant layer but no adhesive layer were obtained. A test sample with dimensions of 50mm x 100mm was randomly selected from the sample. Five test areas were randomly chosen within the sample, and the particle size of the corresponding particles in each test area was read at a certain magnification. The number and particle size of particles in each test area were counted, and the arithmetic mean of the particle sizes in all test areas was taken as the average particle size. To ensure the accuracy of the test results, 10 test samples were subjected to the above test, and the average value of each test sample was taken as the final test result.

[0240] The average particle size of the polymer particles in the adhesive layer was tested using the following method:

[0241] Using a scanning electron microscope (SEM) according to JY / T010-1996, SEM images of the separator were acquired. A test sample with dimensions of 50mm x 100mm was randomly selected. Five test areas were randomly chosen within the sample, and the particle size of each particle in each area was read at a certain magnification. The number and particle size of particles in each test area were counted, and the arithmetic mean of the particle sizes in all test areas was taken as the average particle size. To ensure the accuracy of the test results, 10 test samples were subjected to the above test, and the average value of each test sample was taken as the final test result.

[0242] The testing instrument was a ZEISS Sigma 300. It should be noted that when the particles are irregularly shaped, the distance between the two furthest points on the particle is taken as the particle size.

[0243] (2) Compression modulus test of the separator

[0244] Step 1: Sample pretreatment: (1) Use a die to punch the release film. Stacking order: die / white paper / release film / white paper / pressing block. Punch 5 layers at a time. 100 layers are a group. Make 3 groups of parallel samples. Sample size is 60mm*70mm. (2) Use a guillotine cutter to punch the aluminum-plastic film with a size of 90mm*200mm. (3) Fold the aluminum-plastic film along the length. Fix the center of the four sides of the punched release film sample with green glue and place it in an aluminum-plastic film packaging bag (Pocket). (4) Use a top-side sealing machine to seal the two long sides of the sample. Then vacuum seal the top. The sealing machine is heated to 185℃. (5) Place a pad in the center of the sealed sample and mark the frame. (6) Measure the thickness of the release film within the marked position with a micrometer. 4 points on the long side and 3 points on the short side.

[0245] Step 2: Sample testing: (1) Turn on the in-situ expansion testing system IEST SWE2110 (Yuaneng Technology Co., Ltd.), open the operating software MISS, pressure calibration; select compression test (transient), thickness calibration; (2) Place the sample in the upper and lower clamps, move the upper clamp to ensure that the upper clamp is in the position marked on the sample frame; (3) Click the MISS software to start the experiment. After the test is completed, measure the sample thickness M1; mark the clamp indentation positions on the upper and lower sides of the sample with a marker; (4) Repeat steps 2-3 and test again.

[0246] Step 3: Data processing: (1) Stress = Pressure * 10 / Fixture area; Deformation = Initial thickness M1 - Real-time thickness; Strain = Deformation / Initial thickness; (2) Plot the stress-strain curve with strain as the abscissa and stress as the ordinate; Linear fitting of the stress / strain curve from 3MPa to 5MPa yields the compressive modulus of the isolation membrane.

[0247] (3) Test of the average gap size between the positive and negative electrode plates

[0248] The prepared battery cell was discharged to the lower cutoff voltage of 2.8V. Computed Tomography (CT) was used to obtain cross-sectional images of the electrode assembly using X-rays. Based on these images, the distance D1 between the outer surface of the 6th positive electrode layer and the inner surface of the 10th positive electrode layer was measured. The battery cell was disassembled, and the thicknesses t1, t2, and t3 of the positive electrode, negative electrode, and separator were measured. Three positive electrode layers, four negative electrode layers, and eight separator layers were disposed between the outer surface of the 6th positive electrode layer and the inner surface of the 10th positive electrode layer; eight gaps were formed between the outer surface of the 6th positive electrode layer and the inner surface of the 10th positive electrode layer.

[0249] Gap size = (D1 - 3 × t1 - 4 × t2 - 8 × t3) / 8.

[0250] It should be noted that the thickness t3 is the thickness measured on the portion of the separator without protruding polymer particles.

[0251] (4) Cycle performance test of individual battery cells

[0252] At 45℃, charge the battery cell at a constant current of 1C to 4.2V, then continue charging at a constant voltage until the current is less than or equal to 0.05C. At this point, the battery cell is fully charged, and the charging capacity at this point is recorded as the first charge capacity. After letting the battery cell rest for 5 minutes, discharge it at a constant current of 1C to 2.8V. This completes one charge-discharge cycle, and the discharge capacity at this point is recorded as the first discharge capacity. Perform cyclic charge-discharge tests on the battery cells using the above method, and record the discharge capacity after each cycle. The capacity retention rate (%) of the battery cell after 1000 cycles at 45℃ = discharge capacity after 1000 cycles / discharge capacity of the first cycle × 100%.

[0253] Table 1

[0254] The test results above show that the glass transition temperature T specified in this disclosure is suitable. gA separator made of polymer particles at 45℃-100℃ can have a high compressive modulus. This separator can also improve the average gap size between the positive and negative electrodes and improve the cycle performance of the battery cell.

[0255] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. An isolation film, wherein, The separator film comprises a porous substrate, a coating layer provided on at least one side of the porous substrate, the coating layer comprising inorganic particles and polymer particles, the polymer particles having a glass transition temperature T g of 45°C to 100°C.

2. The separator film according to claim 1, wherein The glass transition temperature T of the polymer particles g The temperature range is 70℃-100℃.

3. The separator film according to any one of claims 1-2, wherein, The average particle diameter of the polymer particles is 8 μm to 30 μm.

4. The separator film according to any one of claims 1 to 3, wherein The average particle diameter of the polymer particles is 12 μm to 28 μm.

5. The separator film according to any one of claims 1 to 4, wherein The weight average molecular weight of the polymer particles is 200,000 to 3,000,000.

6. The separator film according to any one of claims 1 to 5, wherein The weight average molecular weight of the polymer particles is 800,000 to 2,800,000.

7. The separator film according to any one of claims 1 to 6, wherein The polymer particles include a copolymer of at least two of an acrylic ester monomer unit, an ethylenically unsaturated acid monomer unit, an ethylenically unsaturated acid salt monomer unit, an ethylenically unsaturated nitrile monomer unit, an ethylenically unsaturated amide monomer unit, a styrene monomer unit, and an olefin monomer unit.

8. The separator film according to claim 7, wherein The polymer particles include one or more of a copolymer of an acrylic ester monomer unit-styrene monomer unit, a copolymer of an acrylic ester monomer unit-ethylenically unsaturated acid monomer unit-styrene monomer unit, an acrylic ester monomer unit-ethylenically unsaturated amide monomer unit-ethylenically unsaturated nitrile monomer unit, an acrylic ester monomer unit-ethylenically unsaturated acid monomer unit-ethylenically unsaturated amide monomer unit, an acrylic ester monomer unit-ethylenically unsaturated acid monomer unit-ethylenically unsaturated amide monomer unit-ethylenically unsaturated nitrile monomer unit, an acrylic ester monomer unit-ethylenically unsaturated acid monomer unit-ethylenically unsaturated amide monomer unit-ethylenically unsaturated nitrile monomer unit, an acrylic ester monomer unit-ethylenically unsaturated acid monomer unit-ethylenically unsaturated amide monomer unit-ethylenically unsaturated nitrile monomer unit, an ethylenically unsaturated acid monomer unit-styrene monomer unit, a styrene monomer unit-ethylenically unsaturated nitrile monomer unit, and a styrene monomer unit-olefin monomer unit-ethylenically unsaturated nitrile monomer unit.

9. The separator film according to any one of claims 7 to 8, wherein, The acrylic ester monomer unit includes one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, and acetoxyethyl methacrylate; and / or, The ethylenically unsaturated acid monomer unit includes one or more of acrylic acid, methacrylic acid, butenoic acid, and heptenoic acid; and / or, The ethylenically unsaturated acid salt monomer unit includes one or more of lithium acrylate, lithium methacrylate, sodium acrylate, sodium methacrylate, ammonium acrylate, and ammonium methacrylate; and / or, The ethylenically unsaturated nitrile monomer unit includes one or more of acrylonitrile, methacrylonitrile, and fumaronitrile; and / or, The olefinically unsaturated amide monomer unit includes one or more of acrylamide, N-hydroxymethyl acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N-butyl acrylamide, 2-methyl acrylamide, N-methoxymethyl acrylamide, N-isopropoxymethyl acrylamide, N-butoxymethyl acrylamide, N-isobutoxymethyl acrylamide, N-octyloxymethyl acrylamide, N-carboxymethoxymethyl acrylamide; and / or, The olefinic monomer unit includes one or more of butadiene, pentadiene, isoprene.

10. The separator membrane according to any one of claims 1 to 9, wherein, The polymer particles are embedded in the inorganic particles and form protrusions on the surface of the coating.

11. The separator film according to claim 10, wherein The mass content of the inorganic particles in the coating is 55% to 92%; and / or, The mass content of the polymer particles in the coating is 5% to 40%.

12. The separator film according to any one of claims 10 to 11, wherein The inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of electrochemical reaction; and / or, The average particle diameter of the inorganic particles is 200 nm to 1000 nm.

13. The separator membrane according to any one of claims 1 to 9, wherein, The coating includes a heat-resistant layer and a bonding layer, the bonding layer is provided on at least a part of the surface of the heat-resistant layer or the porous substrate, the inorganic particles are provided in the heat-resistant layer, and the polymer particles are provided in the bonding layer.

14. The separator film according to claim 13, wherein The mass content of the inorganic particles in the heat-resistant layer is 50% to 99%; and / or, The mass content of the polymer particles in the bonding layer is 80% to 95%.

15. The separator film according to any one of claims 13 to 14, wherein The inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of electrochemical reaction; and / or, The average particle diameter of the inorganic particles is 200 nm to 1000 nm.

16. The separator film according to claim 13, wherein The heat-resistant layer further includes a fibrous material; optionally, the fibrous material includes nanocellulose.

17. The separator membrane of claim 16, wherein, The fibrous material satisfies at least one of the following conditions (1) to (4): (1) The average diameter of the fibrous material is 10 nm to 40 nm; (2) The average length of the fibrous material is 100 nm to 600 nm; (3) The aspect ratio of the fibrous material is 5 to 50; (4) The mass content of the fibrous material in the heat-resistant layer is 5% to 25%.

18. The separator membrane according to any one of claims 16-17, wherein, The inorganic particles include first inorganic particles, the first inorganic particles being aggregates of a plurality of primary particles.

19. The separator membrane of claim 18, wherein, The first inorganic particles satisfy at least one of the following conditions (1) to (3): (1) The average particle diameter of the primary particles constituting the aggregates is 10 nm to 50 nm; (2) The mass content of the first inorganic particles in the heat-resistant layer is 55% or more; (3) The average particle diameter of the primary particles constituting the aggregates is 10 nm to 50 nm. (3) the first inorganic particles include one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide compound, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

20. The separator membrane according to any one of claims 18-19, wherein, The inorganic particles further include second inorganic particles, and the average particle diameter of the second inorganic particles is greater than the average particle diameter of the primary particles constituting the aggregates.

21. The separator film according to claim 20, wherein The second inorganic particles satisfy at least one of the following conditions (1) to (4): (1) the second inorganic particles have a primary particle morphology; (2) the average particle diameter of the second inorganic particles is 200 nm to 500 nm; (3) the mass content of the second inorganic particles in the heat-resistant layer is 5% to 30%; (4) the second inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of electrochemical reaction.

22. The separator according to any one of claims 1 to 21, wherein the thickness of the coating layer is 0.5 μm to 5 μm; and / or the material of the porous substrate includes polyolefin.

23. The separator membrane of any one of claims 1-22, wherein, The compression modulus of the separator is greater than or equal to 240 MPa, and is optionally 245 MPa to 350 MPa.

24. A battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator according to any one of claims 1 to 23.

25. The battery cell of claim 24, wherein, The porous substrate has a coating layer on at least one side facing the positive electrode sheet.

26. An electric device comprising the battery cell according to any one of claims 24 to 25.

Images