Secondary battery cell, battery device, electric device, and separator

Abstract

Provided is a secondary battery cell, comprising an electrode assembly. The electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator; the separator is arranged between the positive electrode sheet and the negative electrode sheet; the separator comprises a porous substrate film and a porous coating located on one side or both sides of the porous substrate film; the porous coating comprises silicon-containing organic cross-linked resin particles; and the compressive modulus of the separator is 50-86 MPa. The secondary battery cell has high energy density, high reliability and good cycle performance.

Description

Secondary battery cells, battery devices, electrical devices, separators

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510198839.9, filed on February 21, 2025, entitled “Secondary Battery Cell, Battery Device, Electrical Device, Separator”, the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] As the application range of rechargeable battery cells becomes increasingly wide, the demands on them are also growing, with higher requirements for energy density and electrochemical performance. Therefore, how to enable rechargeable battery cells to possess both high energy density and good electrochemical performance is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This disclosure provides a secondary battery cell, a battery device, an electrical device, and a separator. The secondary battery cell has high energy density, high reliability, and good cycle performance.

[0006] In a first aspect, this disclosure provides a secondary battery cell, including an electrode assembly, which includes a positive electrode, a negative electrode, and a separator. The separator is disposed between the positive electrode and the negative electrode. The separator includes a porous base film and a porous coating located on one or both sides of the porous base film. The porous coating includes silicon-containing organic crosslinked resin particles, and the compressive modulus of the separator is 50 MPa-86 MPa.

[0007] When the separator is heated, the porous base membrane shrinks, causing the silicon-containing organic cross-linked resin particles in the porous coating to rapidly contact and compress, thus applying a force to the porous base membrane opposite to the direction of thermal shrinkage. The silicon-containing organic cross-linked resin particles disclosed herein can act as a skeletal support in the porous coating, thereby resisting the thermal shrinkage of the porous base membrane and improving the overall heat resistance of the separator. It is understood that the separator has good heat resistance and maintains good deformation resistance even at high temperatures. Therefore, when used in secondary battery cells, it can reduce the probability of short circuits between the positive and negative electrodes, improving the reliability of the secondary battery cells. Compared with inorganic ceramic materials such as boehmite and alumina, the porous coating of this disclosure uses low-density silicon-containing organic cross-linked resin particles, thereby enabling the secondary battery cells to have high-quality energy density. The separator disclosed herein has a compressive modulus of 50 MPa-86 MPa. Within this range, the separator can resist deformation from irregular foreign particles, thereby reducing separator damage, minimizing the formation of weak points, improving the separator's voltage breakdown strength, and reducing the self-discharge of the secondary battery cell. Simultaneously, the separator exhibits good resilience, and its deformation easily recovers during the cyclic charging and discharging of the secondary battery cell. This allows the separator to maintain a good pore structure, good electrolyte wettability, and good electrolyte retention. Furthermore, the good resilience of the separator also helps reduce the expansion force of the electrode assembly on the casing. Therefore, the secondary battery cell of this disclosure combines high energy density, high reliability, and good cycle performance.

[0008] In some embodiments, the compressive modulus of the separator is 65 MPa-81 MPa.

[0009] In some embodiments, the compressive modulus of the porous base membrane is 100MPa-300MPa.

[0010] In some embodiments, the average pore size of the porous base film is 25 nm-80 nm.

[0011] In some embodiments, the porosity of the porous base membrane is 25%-60%, optionally 30%-50%.

[0012] In some embodiments, the thickness of the porous base film is 3μm-11μm, and optionally 3μm-7μm.

[0013] In some embodiments, the porous base membrane is made of polyethylene, and the weight-average molecular weight of polyethylene is 600,000 to 2,000,000; or, the porous base membrane is made of polypropylene, and the weight-average molecular weight of polypropylene is 400,000 to 800,000.

[0014] In some embodiments, the morphology of the silicon-containing organic crosslinked resin particles includes one or more of spherical, near-spherical, ellipsoidal, and near-ellipsoidal shapes. Spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies ensure good overlap between particles, and the presence of voids between particles facilitates the construction of a stable spatial network structure, thereby improving the ion transport characteristics and resistance to external extrusion of the separator. Furthermore, the larger voids between particles with spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies reduce the impact of the porous coating on the air permeability of the separator, resulting in high air permeability and high ion conductivity overall, thus improving the kinetic performance of the secondary battery cell. Moreover, the larger porosity between particles with spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies improves the wettability and electrolyte retention of the separator, further enhancing the cycle performance and kinetic performance of the secondary battery cell.

[0015] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles is less than 1 μm, and can be selected as 60 nm-800 nm.

[0016] In some embodiments, the particle size distribution (Dv90-Dv10) / Dv50 of the silicone organic crosslinked resin particles is 0.2-1.1.

[0017] In some embodiments, the true density of the silicon-containing organic cross-linked resin particles is 1.0 g / cm³. 3 -1.5g / cm 3 This allows secondary battery cells using the separator membrane disclosed herein to have a higher mass energy density.

[0018] In some embodiments, the porous coating further includes polymer binder particles with a volume distribution particle size Dv50 of 6 μm-18 μm.

[0019] In some embodiments, the polymer binder particles include one or more of fluoropolymer binder particles and non-fluoropolymer binder particles.

[0020] In some embodiments, the polymer binder particles comprise an aggregate of primary particles.

[0021] In some embodiments, the polymer binder particles account for 5%-30% of the mass of the porous coating.

[0022] In some embodiments, polymer binder particles are embedded in silicone-containing organic crosslinked resin particles and form protrusions on the surface of the porous coating.

[0023] In some embodiments, the porous coating includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on the porous base film, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer or the porous base film. Silicon-containing organic crosslinked resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0024] In some embodiments, the thickness of the porous coating is 0.4 μm-5 μm.

[0025] In some embodiments, the total thickness of the separator is 4.5 μm-14 μm.

[0026] In some embodiments, the porosity of the separator is 25%-60%, optionally 40%-48%.

[0027] In some embodiments, the ratio of the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles to the average pore size of the porous base membrane is greater than or equal to 1.2. This can reduce pore clogging problems and improve the air permeability and ion conduction properties of the separator.

[0028] In some embodiments, the silicon-containing organic crosslinked resin particles have no melting point. The absence of a melting point in the silicon-containing organic crosslinked resin particles indicates good heat resistance and thermal stability, thereby better resisting the thermal shrinkage of the porous base film, improving the heat resistance of the separator, and enhancing the reliability of the secondary battery cells.

[0029] In some embodiments, the silicon-containing organic crosslinked resin particles have no glass transition temperature. The absence of a glass transition temperature in the silicon-containing organic crosslinked resin particles indicates good heat resistance and thermal stability, thereby better resisting the thermal shrinkage of the porous base film, improving the heat resistance of the separator, and enhancing the reliability of the secondary battery cells.

[0030] In some embodiments, the swelling degree of the silicon-containing organic crosslinked resin particles after being immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%. The low swelling degree of the silicon-containing organic crosslinked resin particles in organic solvents results in high structural stability during long-term use of the secondary battery cell, thereby improving the problem of decreased air permeability of the separator during use.

[0031] In some embodiments, the dissolution rate of the silicon-containing organic crosslinked resin particles after immersion at 60°C for 7 days in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 3%. The low dissolution rate of the silicon-containing organic crosslinked resin particles in organic solvents indicates high structural stability during long-term use of the secondary battery cell and high chemical stability in the electrolyte, thereby enabling the secondary battery cell to have longer cycle stability.

[0032] In some embodiments, the cyclic voltammetry curve of the silicon-containing organic crosslinked resin particles in the first cycle does not exhibit an oxidation peak in the voltage range of 2.5V to 4.4V. The absence of an oxidation peak in the cyclic voltammetry curve of the silicon-containing organic crosslinked resin particles in the voltage window of ≥2.5V and <4.4V indicates that the silicon-containing organic crosslinked resin particles are stable within this voltage window and do not undergo electrochemical redox reactions. This allows the secondary battery cell to possess a high voltage plateau and high-quality energy density.

[0033] In some embodiments, the silicon-containing organic crosslinked resin particles contain carbon-carbon bonds and silicon-oxygen structures.

[0034] In some embodiments, the silicon-containing organic crosslinked resin particles are a network structure formed with carbon-carbon bonds as the main chain and the side chains contain silicon-oxygen structures.

[0035] In some embodiments, the silicon-containing organic crosslinked resin particles are a network structure formed with carbon-carbon bonds as the main chain, and the side chains contain silicon-oxygen structures and benzene ring structures.

[0036] The rigidity of the benzene ring structure gives silicon-containing organic crosslinked resin particles good heat resistance. By using silicon-containing organic crosslinked resin particles with benzene ring structures in separators, it is possible to better generate forces to resist the shrinkage of porous base membranes, thereby improving the overall thermal shrinkage of the separator, enhancing its heat resistance, and improving the reliability of secondary battery cells.

[0037] In some embodiments, the silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures include crosslinked structural units, which include divinylbenzene structural units, diethylene glycol divinyl ether structural units, triethylene glycol divinyl ether structural units, diallyl maleate structural units, ethylene glycol dimethacrylate structural units, 1,4-butanediol diacrylate structural units, 1,6-hexanediol diacrylate structural units, 1,8-octanediol diacrylate structural units, trimethylolpropane triacrylate structural units, and pentaerythritol trimethacrylate structural units. One or more of the following structural units: tetraethylene glycol dimethacrylate, dipropylene glycol diacrylate, 2,2,4-trimethyladipyl di[2-ethylaziridinium], 1,1-azeloyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0038] In some embodiments, the silicon-containing organic crosslinked resin particles include polysilsesquioxane, and the weight-average molecular weight of the polysilsesquioxane is 10,000 to 100,000.

[0039] In some embodiments, the silicone-containing organic crosslinked resin particles comprise polysilsesquioxane, and the polysilsesquioxane has the following structural formula:

[0040] R1 and R2 each independently include an alkyl group with 1-12 carbon atoms, an unsaturated hydrocarbon group with 2-12 carbon atoms, or a phenyl group, n = 50-1000.

[0041] In some embodiments, polysilsesquioxanes comprise at least one of the following structural formulas:

[0042] Ph represents phenyl, n = 50-1000.

[0043] Secondly, this disclosure provides a battery device comprising a plurality of secondary battery cells according to the first aspect of this disclosure.

[0044] Thirdly, this disclosure provides an electrical device that includes a secondary battery cell according to the first aspect of this disclosure or a battery device according to the second aspect of this disclosure.

[0045] Fourthly, this disclosure provides a separator membrane, which includes a porous base membrane and a porous coating located on one or both sides of the porous base membrane. The porous coating includes silicon-containing organic crosslinked resin particles, and the separator membrane has a compressive modulus of 50 MPa-86 MPa. Attached Figure Description

[0046] 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.

[0047] Figure 1 shows a schematic diagram of a secondary battery cell provided in some embodiments of this disclosure.

[0048] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this disclosure.

[0049] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0050] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the secondary battery cell, battery device, power-consuming device, and separator of this disclosure. 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.

[0051] 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.

[0052] 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 to be included in the disclosure of this disclosure.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0057] 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.

[0058] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0059] The secondary battery cells mentioned in the embodiments of this disclosure can independently perform charge and discharge functions, and can continue to be used by recharging after discharge to activate the active materials. The secondary battery cells can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this disclosure are not limited to this. Figure 1 shows a cuboid secondary battery cell 5 as an example.

[0060] The secondary battery cells provided in the embodiments of this disclosure may include, but are not limited to, lithium battery cells and sodium battery cells, such as lithium-ion battery cells, sodium-ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0061] The secondary battery cell provided in the embodiments of this disclosure includes an electrode assembly, in which a positive electrode sheet, a separator, and a negative electrode sheet are formed by a winding process. The secondary battery cell also includes an outer packaging, which is used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging 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).

[0062] The battery apparatus 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 secondary battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0063] In some embodiments, a battery cell assembly is typically formed by arranging multiple secondary battery cells.

[0064] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple secondary battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple secondary battery cells together with cable ties.

[0065] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0066] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0067] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple secondary battery cells to the housing.

[0068] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0069] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0070] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0071] The technical solutions described in this disclosure are applicable to various electrical devices that use secondary battery cells or battery devices, such as, but 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. Secondary battery cells and battery devices are used to store or provide electrical energy.

[0072] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0073] In the context of this disclosure, the "silicon-containing organic crosslinked resin particles" primarily improve heat resistance in the porous coating of the separator and have almost no adhesive properties. The "polymer binder particles" improve the adhesion between the separator and the electrode in the porous coating of the separator and have virtually no high-temperature resistance.

[0074] Melting point can be tested as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of a 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 DSC curve is used to determine whether the silicon-containing organic crosslinked resin particles have a melting point below 300℃. Silicon-containing organic crosslinked resin particles having no melting point means that the DSC curve of the silicon-containing organic crosslinked resin particles has no melting peak.

[0075] The swelling degree of silicon-containing organic crosslinked resin particles can be tested as follows: Take an appropriate amount of sample (e.g., about 1g), denoted as m1, and place it in a semi-permeable membrane sample bag. Seal the bag; the sample bag should be permeable to the solvent but not to the sample. Immerse the sample bag in an appropriate amount of solvent (e.g., about 50g) at 60°C for 7 days (7*24h). After that, remove the sample bag, remove the sample from the bag, wipe off excess solvent, and weigh the sample again (m2). Swelling degree = (m2-m1) / m1×100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0076] The dissolution rate of silicon-containing organic crosslinked resin particles can be tested as follows: Take an appropriate amount of sample (e.g., about 1g), and record its mass as m1. Place it in a semi-permeable membrane sample bag, seal it, and record the total mass of the sample bag as m2. The sample bag is permeable to the solvent but not to the sample. Immerse the sample bag in an appropriate amount of solvent (e.g., about 50g) at 60℃ for 7 days (7*24h). After that, remove the sample bag, drain it, dry it, and weigh the total mass of the sample bag again as m3. Dissolution rate = (m2-m3) / m1×100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0077] The oxidation peak potential of the cyclic voltammetry curve of silicon-containing organic crosslinked resin particles can be tested as follows: Silicon-containing organic crosslinked resin particles, binder polyacrylate, and conductive agent conductive carbon black are dissolved in water at a solid content mass ratio of 64:7:29 to prepare a slurry. The slurry is coated onto aluminum foil as the positive electrode, and lithium foil is used as the negative electrode to assemble a coin cell. Cyclic voltammetry (CV) is performed on the coin cell at a scan rate of 0.10 mV / s, a voltage range of 2.50 V–5.00 V, and 3 cycles. The voltage corresponding to the peak point of the first cyclic voltammetry curve is taken as the oxidation peak potential. The electrolyte used in the test is LiPF6 with a concentration of 1 mol / L. The solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of 3:7.

[0078] Glass transition temperature T of silicon-containing organic crosslinked resin particles g The test can be performed as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) 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 silicon-containing organic crosslinked resin particles is obtained through the DSC curve. g Or determine whether the silicon-containing organic cross-linked resin particles have a glass transition temperature T. g Glass transition temperature T g This refers to the glass transition temperature from the glassy state to the elastic state, which exhibits a step-like change on the DSC curve. Silicon-containing organic crosslinked resin particles have no glass transition temperature T0. g This means that the DSC curve of silicon-containing organic crosslinked resin particles does not show a step-like change in the range below 300℃.

[0079] Dv10, Dv50, and Dv90 represent the particle sizes corresponding to a cumulative volumetric distribution percentage of 10%, 50%, and 90%, respectively. These values ​​can be determined using a laser particle size analyzer, referring to GB / T 19077-2016. During testing, add 1g of the sample to a clean small beaker and 20ml of deionized water. Sonicate at 53kHz / 120W for 5 minutes to ensure complete dispersion. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated solution to ensure uniform dispersion, place it in the sample cell as required, and begin measuring the particle size. A MasterSizer 3000 laser particle size analyzer can be used as the testing instrument.

[0080] The separator is a crucial component supporting the electrochemical processes of charging and discharging in a secondary battery cell. Commonly used separators are mostly made of polyolefin materials; however, these materials have low glass transition temperatures and exhibit significant thermal shrinkage upon heating. To improve the heat resistance of the separator, inorganic ceramic materials such as boehmite or alumina are often used as heat-resistant fillers and binders to construct porous coatings. Boehmite and alumina have high densities; for the same packing volume, their mass is greater than other materials, thus affecting the energy density of the secondary battery cell.

[0081] Furthermore, it is understandable that electrode assemblies are formed from positive electrode plates, negative electrode plates, and separators. Existing secondary battery cells typically employ stacked or wound electrode assemblies. Compared to stacked electrode assemblies, wound electrode assemblies offer advantages such as faster production speed, better continuity, lower equipment requirements, and easier consistency control. Before encapsulating the wound electrode assembly in the casing, existing technologies usually require shaping. This improves the thickness uniformity of the electrode assembly and eliminates wrinkles in the separator, ensuring a tight fit between the separator and the positive and negative electrode plates, thereby shortening the ion transport distance and reducing internal resistance. However, irregular foreign particles during the shaping process, such as magnetic particles, precipitated metals, hard active material particles, and burrs, can cause deformation, indentation, and puncture damage to the separator. This can easily lead to micro-short circuits within the secondary battery cell, resulting in significant self-discharge. Self-discharge refers to the spontaneous decrease in the open circuit voltage (OCV) of a secondary battery cell under a certain state of charge. Secondary battery cells have high self-discharge, which reduces their actual usable capacity and worsens their cycle life.

[0082] This disclosure provides a secondary battery cell, a battery device and an electrical device containing the same, and by adjusting the separator parameters of the secondary battery cell, the secondary battery cell can have high energy density, high reliability and good cycle performance.

[0083] The secondary battery cell provided in this embodiment includes an electrode assembly, which includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the positive and negative electrode.

[0084] The electrode assembly disclosed herein may be a wound electrode assembly.

[0085] The separator provided in this embodiment includes a porous base membrane and a porous coating located on one or both sides of the porous base membrane. The porous coating includes silicon-containing organic crosslinked resin particles, and the compressive modulus of the separator is 50 MPa-86 MPa.

[0086] When the separator is heated, the porous base membrane shrinks, causing the silicon-containing organic cross-linked resin particles in the porous coating to rapidly contact and compress, thus applying a force to the porous base membrane opposite to the direction of thermal shrinkage. The silicon-containing organic cross-linked resin particles disclosed herein can act as a skeletal support in the porous coating, thereby resisting the thermal shrinkage of the porous base membrane and improving the overall heat resistance of the separator. It is understood that the separator has good heat resistance and maintains good deformation resistance even at high temperatures. Therefore, when used in secondary battery cells, it can reduce the probability of short circuits between the positive and negative electrodes, improving the reliability of the secondary battery cells. Compared with inorganic ceramic materials such as boehmite and alumina, the porous coating of this disclosure uses low-density silicon-containing organic cross-linked resin particles, thereby enabling the secondary battery cells to have high-quality energy density.

[0087] The separator disclosed herein has a compressive modulus of 50 MPa-86 MPa. Within this range, the separator can generate deformation that resists irregular foreign particles, thereby reducing separator damage, reducing the formation of weak points in the separator, improving the separator's withstand voltage breakdown strength, and reducing the self-discharge of the secondary battery cells. At the same time, the separator has good resilience, and its deformation is easily recovered during the cyclic charging and discharging of the secondary battery cells. This allows the separator to maintain a good pore structure, good electrolyte wettability, and good electrolyte retention. In addition, the good resilience of the separator also helps to reduce the expansion force of the electrode assembly on the casing.

[0088] Therefore, the secondary battery cell disclosed herein can possess high energy density, high reliability, and good cycle performance.

[0089] The compressive modulus of the separator is 50MPa-86MPa, for example, it can be 50MPa, 51MPa, 52MPa, 53MPa, 54MPa, 55MPa, 56MPa, 57MPa, 58MPa, 59MPa, 60MPa, 61MPa, 62MPa, 63MPa, 64MPa, 65MPa, 66MPa, 67MPa, 68MPa, 69MPa, 70MPa, 71MPa, 72MPa, 73MPa, 74MPa, 75MPa, 76MPa, 77MPa, 78MPa, 79MPa, 80MPa, 81MPa, 82MPa, 83MPa, 84MPa, 85MPa, 86MPa, or any combination of the above values.

[0090] Optionally, the compressive modulus of the separator is 65MPa-86MPa, 68MPa-86MPa, 70MPa-86MPa, 72MPa-86MPa, 74MPa-86MPa, 65MPa-83MPa, 68MPa-83MPa, 70MPa-83MPa, 72MPa-83MPa, 74MPa-83MPa, 65MPa-81MPa, 68MPa-81MPa, 70MPa-81MPa, 72MPa-81MPa, or 74MPa-81MPa.

[0091] This can further improve the reliability and cycle performance of secondary battery cells.

[0092] The compressive modulus of the separator can be tested using the following method:

[0093] Sample pretreatment: Cut the release film with a die, stacking order: die / white paper / release film / white paper / pressing block, cut 5 layers at a time, 100 layers as a group, make 3 parallel samples, sample size 60mm*70mm; cut the aluminum-plastic film with a size of 90mm*200mm with a guillotine cutter; fold the aluminum-plastic film in half along its length; fix the center position of the four sides of the cut release film sample with green glue and place it in a Pocket bag; use a top-side sealing machine to seal the two long sides of the sample, then vacuum seal the top, the sealing machine heating temperature is 185℃; place a pad in the center position of the sealed sample and mark the frame; 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.

[0094] Sample testing: Turn on the in-situ expansion analyzer (e.g., IEST SWE2110), open the operating software (e.g., MISS), and perform pressure calibration; select compression test (transient), and perform thickness calibration; 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; click the software (e.g., MISS) to start the experiment. After the test is completed, measure the sample thickness M1, and mark the clamp indentation positions on the upper and lower sides of the sample with a marker; repeat the operation to perform the test again.

[0095] Data processing: Plot a stress-strain curve with strain on the x-axis and stress on the y-axis; perform linear fitting of the stress / strain curve from 3MPa to 5MPa to obtain the compressive modulus of the isolation membrane. Strain = Deformation / Initial sample thickness, Deformation = Initial sample thickness - Real-time sample thickness.

[0096] In some embodiments, the compressive modulus of the porous base membrane can be 100MPa-300MPa, for example, it can be 100MPa, 110MPa, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa, 190MPa, 200MPa, 210MPa, 220MPa, 230MPa, 240MPa, 250MPa, 260MPa, 270MPa, 280MPa, 290MPa, 300MPa, or any range of the above values.

[0097] The test method for the compressive modulus of porous base membranes can refer to the test method for the compressive modulus of separator membranes.

[0098] The compressive modulus of porous membranes can be obtained by adjusting one or more of the parameters of the porous membrane, such as material, pore size, and porosity.

[0099] In some embodiments, the porous base membrane is made of polyethylene, and the weight-average molecular weight of polyethylene is 600,000 to 2,000,000, for example, it can be 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, 2,000,000, or any range of the above values.

[0100] In some embodiments, the porous base membrane is made of polypropylene, and the weight-average molecular weight of the polypropylene is 400,000 to 800,000, for example, it can be 400,000, 420,000, 440,000, 460,000, 480,000, 500,000, 520,000, 540,000, 560,000, 580,000, 600,000, 620,000, 640,000, 660,000, 680,000, 700,000, 720,000, 740,000, 760,000, 780,000, 800,000, or any range of the above values.

[0101] In some embodiments, the average pore size of the porous base film can be 25nm-80nm, for example, it can be 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, or any range of the above values.

[0102] Optionally, the average pore size of the porous base film can be 35nm-80nm, 40nm-80nm, 45nm-80nm, 50nm-80nm, 35nm-75nm, 40nm-75nm, 45nm-75nm, or 50nm-75nm.

[0103] The average pore size of the porous membrane can be measured using a capillary porosity analyzer (bubble point method). An exemplary testing method is as follows: Take a circular sample with a diameter of 25 mm, and drop 3-5 drops of wetting solution onto it. After the sample is completely wetted, place it in a mold. Then, use an inert gas (such as nitrogen) to compress the wetting solution in the pores of the sample. The compression pressure and flow rate are inversely proportional to the pore size. The average pore size of the sample is obtained through software sampling and pressure-pore size conversion analysis. The testing instrument can be a PMI CFP 1500 pore size analyzer, with a testing pressure ranging from 100 psi to 350 psi.

[0104] In some embodiments, the porosity of the porous base membrane can be 25%-60%, for example, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any range of the above values.

[0105] Optionally, the porosity of the porous membrane can be 30%-50%.

[0106] In some embodiments, the thickness of the porous base film can be 3μm-11μm, and optionally 3μm-7μm.

[0107] The silicon-containing organic crosslinked resin particles disclosed herein are commercially available or can be prepared according to the preparation method provided herein.

[0108] In some embodiments, the true density of the silicon-containing organic crosslinked resin particles can be 1.0 g / cm³. 3 -1.5g / cm 3 .

[0109] Currently, the true density of inorganic particles such as boehmite and alumina is typically 2.5 g / cm³. 3 -3.5g / cm 3 The silicon-containing organic crosslinked resin particles disclosed herein have a low true density, thereby enabling secondary battery cells using the separator membrane of this disclosure to have a higher mass energy density.

[0110] In some embodiments, the morphology of the silicon-containing organic crosslinked resin particles may include one or more of the following: spherical, near-spherical, ellipsoidal, and near-ellipsoidal.

[0111] Spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies ensure good overlap between particles, and the inter-particle voids facilitate the construction of a stable spatial network structure, thereby improving the ion transport characteristics and resistance to external pressure of the separator. Furthermore, the larger voids between particles with spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies reduce the impact of porous coatings on the separator's permeability, resulting in high overall permeability and high ion conductivity, thus improving the kinetic performance of the secondary battery cell. Moreover, the larger porosity between particles with spherical, near-spherical, ellipsoidal, and near-ellipsoidal morphologies enhances the separator's wettability and electrolyte retention, further improving the cycle performance and kinetic performance of the secondary battery cell.

[0112] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles is less than 1 μm, and can be selected from 60 nm to 800 nm, for example, it can be 60 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or any range of the above values.

[0113] Optionally, the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles can be 80nm-600nm, 100nm-600nm, 150nm-600nm, 80nm-500nm, 100nm-500nm, 150nm-500nm, 80nm-450nm, 100nm-450nm, 150nm-450nm, 80nm-400nm, 100nm-400nm, or 150nm-400nm.

[0114] In some embodiments, the particle size distribution (Dv90-Dv10) / Dv50 of the silicon-containing organic crosslinked resin particles can be 0.2-1.1, for example, it can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, or any range of the above values.

[0115] In some embodiments, the ratio of the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles to the average pore size of the porous base membrane can be greater than or equal to 1.2. The volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles and the average pore size of the porous base membrane have the same unit, for example, nm. This can reduce pore clogging problems and improve the air permeability and ion conduction properties of the separator.

[0116] In some embodiments, the silicone-containing organic crosslinked resin particles have no melting point.

[0117] The absence of melting point in silicon-containing organic crosslinked resin particles indicates good heat resistance and thermal stability, which can better resist the thermal shrinkage of porous base films, improve the heat resistance of separators, and enhance the reliability of secondary battery cells.

[0118] In some embodiments, the silicone-containing organic crosslinked resin particles have no glass transition temperature.

[0119] The absence of a glass transition temperature in silicon-containing organic crosslinked resin particles indicates good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of porous base films, improve the heat resistance of the separator, and enhance the reliability of secondary battery cells.

[0120] In some embodiments, the swelling degree of the silicon-containing organic crosslinked resin particles after being soaked in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%.

[0121] Silicon-containing organic cross-linked resin particles have low swelling in organic solvents and high structural stability during long-term use of secondary battery cells, thereby improving the problem of decreased air permeability of the separator during use.

[0122] In some embodiments, the dissolution rate of the silicon-containing organic crosslinked resin particles after being soaked in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%.

[0123] Silicon-containing organic crosslinked resin particles have a low dissolution rate in organic solvents, high structural stability during long-term use of secondary battery cells, and high chemical stability in electrolytes, which can enable secondary battery cells to have longer cycle stability.

[0124] In some embodiments, the cyclic voltammetry curves of the silicon-containing organic crosslinked resin particles during the first cycle do not exhibit oxidation peaks in the voltage range of 2.5V to 4.4V.

[0125] The cyclic voltammetry curve of the silicon-containing organic crosslinked resin particles in the first cycle does not have an oxidation peak in the voltage window range of ≥2.5V and <4.4V, indicating that the silicon-containing organic crosslinked resin particles are stable in the voltage window range of ≥2.5V and <4.4V and will not undergo electrochemical redox reactions. This allows the secondary battery cell to have a high voltage plateau and high quality energy density.

[0126] In some embodiments, the silicon-containing organic crosslinked resin particles include one or more of polysilsesquioxane, silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures.

[0127] [Silicone-containing organic cross-linked resin particles containing carbon-carbon bonds and silicon-oxygen structures]

[0128] In some embodiments, the silicon-containing organic crosslinked resin particles contain carbon-carbon bonds and silicon-oxygen structures.

[0129] Optionally, the silicon-containing organic crosslinked resin particles have a network structure with carbon-carbon bonds as the main chain and silicon-oxygen structures in the side chains.

[0130] Optionally, the silicon-containing organic crosslinked resin particles have a network structure formed with carbon-carbon bonds as the main chain, and the side chains contain silicon-oxygen structures and benzene ring structures.

[0131] The rigidity of the benzene ring structure gives silicon-containing organic crosslinked resin particles good heat resistance. By using silicon-containing organic crosslinked resin particles with benzene ring structures in separators, it is possible to better generate forces to resist the shrinkage of porous base membranes, thereby improving the overall thermal shrinkage of the separator, enhancing its heat resistance, and improving the reliability of secondary battery cells.

[0132] In some embodiments, the silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures include crosslinked structural units. The crosslinked structural units of the silicon-containing organic crosslinked resin particles refer to silicon-free structural units used to connect the silicon-containing structural units. Optionally, the crosslinked structural units may include divinylbenzene structural units, diethylene glycol divinyl ether structural units, triethylene glycol divinyl ether structural units, diallyl maleate structural units, ethylene glycol dimethacrylate structural units, 1,4-butanediol diacrylate structural units, 1,6-hexanediol diacrylate structural units, 1,8-octanediol diacrylate structural units, trimethylolpropane triacrylate structural units, pentaerythritol trimethacrylate structural units, tetraethylene glycol dimethacrylate structural units, and di... The structural unit comprises one or more of the following: tripropylene glycol diacrylate, 2,2,4-trimethyladipyl di[2-ethylaziridinium], 1,1-azeloyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0133] Optionally, the crosslinking structural unit may include a divinylbenzene structural unit.

[0134] Optionally, the crosslinking structural unit may include a divinylbenzene structural unit, as well as diethylene glycol divinyl ether structural units, triethylene glycol divinyl ether structural units, diallyl maleate structural units, ethylene glycol dimethacrylate structural units, 1,4-butanediol diacrylate structural units, 1,6-hexanediol diacrylate structural units, 1,8-octanediol diacrylate structural units, trimethylolpropane triacrylate structural units, pentaerythritol trimethacrylate structural units, tetraethylene glycol dimethacrylate structural units, and di... The structural unit comprises one or more of the following: tripropylene glycol diacrylate, 2,2,4-trimethyladipyl di[2-ethylaziridinium], 1,1-azeloyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0135] Silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures are poorly soluble in both water and organic solvents, such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), and chloroform, at 25°C. They are also insoluble in the mobile phase used in gel permeation chromatography, and the molecular weight of these particles cannot be determined by gel permeation chromatography.

[0136] In some embodiments, silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures have no melting point.

[0137] In some embodiments, silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures have no glass transition temperature.

[0138] In some embodiments, the swelling degree of silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures after being soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%.

[0139] In some embodiments, the dissolution rate of silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures after being soaked at 60°C for 7 days in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 3%.

[0140] In some embodiments, the cyclic voltammetry curves of silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures do not exhibit oxidation peaks in the voltage range of 2.5V to 4.4V during the first cycle.

[0141] Silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures are commercially available or can be prepared according to the preparation method provided in this disclosure.

[0142] A method for preparing silicon-containing organic crosslinked resin particles with carbon-carbon bonds and silicon-oxygen structures includes the following steps: providing a pre-emulsion comprising monomers, crosslinking agents, emulsifiers, initiators, and water; subjecting the pre-emulsion to emulsion polymerization under heating, inert gas protection, and stirring conditions to obtain the product. The monomers include silane coupling agents containing alkenyl and / or acryloyloxy groups. The mass fraction of the crosslinking agent is 3%-18% based on the total mass of monomers and crosslinking agents (100%).

[0143] The monomers include silane coupling agents containing alkenyl and / or acryloyloxy groups, thus initiating free radical generation and cross-linking reactions between monomers, and the monomers also undergo cross-linking reactions with the cross-linking agents. Therefore, using the monomers and cross-linking agents of this disclosure as raw materials, silicon-containing organic cross-linked resin particles with a three-dimensional network molecular structure can be formed, which are not easily softened or deformed at high temperatures and have high heat resistance.

[0144] When the mass fraction of the crosslinking agent is within the above range, silicon-containing organic crosslinked resin particles with good heat resistance can be obtained.

[0145] The mass fraction of the crosslinking agent is 3%-18%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 16%, 17%, 18%, or any combination of the above values.

[0146] Optionally, based on the total mass of monomers and crosslinking agents as 100%, the mass fraction of the crosslinking agent can be 4%-18%, 6%-18%, 8%-18%, 4%-16%, 6%-16%, 8%-16%, 4%-15%, 6%-15%, or 8%-15%.

[0147] When the mass fraction of the crosslinking agent is within the above range, silicon-containing organic crosslinked resin particles with better heat resistance can be obtained.

[0148] In some embodiments, the emulsion polymerization reaction may include the following steps: adding a pre-emulsion dropwise into a reactor containing water under a first temperature, an inert gas protection and stirring conditions, reacting for a first time, then heating to a second temperature to mature the reaction for a second time, to obtain the product.

[0149] In some embodiments, the first temperature can be 55°C-70°C.

[0150] In some embodiments, the first time can be 3h-6h.

[0151] In some embodiments, the second temperature can be 72℃-92℃, for example, it can be 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, or any range of the above values.

[0152] In some embodiments, the second time can be 1h-5h, for example, it can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h, 5h, or any range of the above values.

[0153] The emulsion polymerization reaction is carried out under the protection of an inert gas. In some embodiments, the inert gas may include one or more of nitrogen, argon, and helium.

[0154] In some embodiments, the monomer may include a vinylsilane coupling agent and / or an acryloyloxysilane coupling agent.

[0155] Optionally, the monomer may include γ-methacryloxypropyltris(trimethylsiloxane), (3-acryloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltris(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-tert-butoxyvinylsilane, vinyltri... One or more of the following: (β-methoxyethoxy)silane, ethylenetri[(1-methylvinyl)oxy]silane, vinyltritert-butylperoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, methacryloyloxypropyldimethylmethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, 3-methacryloyloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyldimethylethoxysilane, methylvinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylvinyldimethoxysilane, and 3-(methacryloyloxy)propylmethyldiethoxysilane.

[0156] The crosslinking agent and monomers polymerize to form crosslinked structural units of silicon-containing organic crosslinked resin particles.

[0157] In some embodiments, the crosslinking agent may be a multifunctional crosslinking agent. Optionally, the crosslinking agent may include one or more of the following: divinylbenzene, diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropylene glycol diacrylate, 2,2,4-trimethyladipyl di[2-ethylaziridinium], 1,1-nonaiyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0158] Optionally, the crosslinking agent may include divinylbenzene.

[0159] Optionally, the crosslinking agent may include divinylbenzene and one or more of diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropylene glycol diacrylate, 2,2,4-trimethyladipyl di[2-ethylaziridinium], 1,1-nonaiyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0160] In some embodiments, the emulsifier may include, but is not limited to, one or more of alkyl sulfates, alkyl sulfonates, Tween emulsifiers, fatty alcohol polyoxyethylene ethers, fatty alcohol polyoxypropylene ethers, cetearyl alcohol polyethers, and oleyl alcohol polyethers. Optionally, the emulsifier includes one or more of sodium lauryl sulfate, sodium lauryl sulfonate, Tween 20, Tween 40, lauryl ether-7, lauryl ether-9, lauryl ether-10, and oleyl alcohol polyether-10.

[0161] In some embodiments, the initiator may be one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, and azobisisopropylimidazoline.

[0162] In some embodiments, the mass fraction of the initiator, based on the total mass of monomers and crosslinking agents (100%), can be 0.15%-2.5%, for example, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, or any range of the above values. Optionally, the mass fraction of the initiator can be 0.3%-2.1%, 0.3%-1.9%, 0.3%-1.7%, 0.3%-1.5%, or 0.3%-1.3%.

[0163] In some embodiments, the preemulsion may further include a pH adjuster. Optionally, the pH adjuster may include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia, etc.

[0164] The product obtained from the emulsion polymerization reaction can be used directly as a coating slurry for preparing the release membrane without drying, or the product obtained from the emulsion polymerization reaction can be used as a coating slurry for preparing the release membrane after drying.

[0165] In some embodiments, the method for preparing silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures may further include the steps of: drying the product obtained from the emulsion polymerization reaction, followed by a crushing process and a wet milling process to obtain the final product. The product may include aggregates of primary particles. The product obtained from wet milling can be used directly to prepare a coating slurry for the release liner without drying, or the product obtained from wet milling can be dried before being used to prepare a coating slurry for the release liner.

[0166] In other embodiments, the preparation method of silicon-containing organic crosslinked resin particles containing carbon-carbon bonds and silicon-oxygen structures may further include the steps of: drying the product obtained from the emulsion polymerization reaction, then baking it under an inert gas atmosphere, followed by a crushing process and a wet grinding process to obtain the product. The product may include aggregates of primary particles. The product obtained by wet grinding can be used directly to prepare the coating slurry for the separator without drying, or the product obtained by wet grinding can be used to prepare the coating slurry for the separator after drying.

[0167] In some embodiments, the drying methods for the products obtained from emulsion polymerization may include, but are not limited to, vacuum drying, spray drying, forced air drying, microwave drying, or fluidized bed drying.

[0168] In some embodiments, the drying temperature of the product obtained from the emulsion polymerization reaction can be 80℃-150℃, for example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, or any combination of the above values.

[0169] In some embodiments, the drying time of the product obtained from the emulsion polymerization reaction can be 2h-12h, for example, it can be 2h, 2.4h, 2.8h, 3.2h, 3.6h, 4h, 4.4h, 4.8h, 5.2h, 5.6h, 6h, 6.4h, 6.8h, 7.2h, 7.6h, 8h, 8.4h, 8.8h, 9.2h, 9.6h, 10h, 10.4h, 10.8h, 11.2h, 11.6h, 12h, or any range of the above values.

[0170] Baking is carried out in an inert gas atmosphere. In some embodiments, the inert gas may include one or more of nitrogen, argon, and helium.

[0171] In some embodiments, the baking temperature can be 160℃-250℃, for example, it can be 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, or any range of the above values.

[0172] In some embodiments, the baking time can be 1 hour to 8 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, 6 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours, 8 hours, or any range of the above values. Optionally, the baking time can be 2 hours to 8 hours, 2.4 hours to 8 hours, or 3 hours to 8 hours.

[0173] In some embodiments, the crushing process can employ air jet mills, vibratory mills, mechanical mills, ultrasonic mills, ball mills, etc.

[0174] In some embodiments, the wet milling process may include the following steps: mixing crushed material with a solvent, grinding media and optional dispersant to obtain a mixed slurry, and then milling the mixed slurry to obtain a product.

[0175] Optionally, the solvent for wet milling may include one or more of water, methanol, and ethanol. More preferably, the solvent may include water.

[0176] Optionally, the dispersant used in wet milling may include one or more of polyacrylic acid dispersants, carboxymethyl cellulose dispersants, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. Optionally, the polyacrylic acid dispersant may include one or more of polypropionic acid, sodium polyacrylate, potassium polyacrylate, and ammonium acrylate. Optionally, the carboxymethyl cellulose dispersant may include one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, and potassium carboxymethyl cellulose.

[0177] Optionally, the polishing media may include one or more of zirconia balls, alumina balls, and silicon nitride balls.

[0178] Optionally, the average particle size of the grinding media can be 0.1 mm to 2 mm.

[0179] Optionally, the grinding speed can be 500rpm-3000rpm.

[0180] [Polysilsesquioxane]

[0181] In some embodiments, the silicone-containing organic crosslinked resin particles include polysilsesquioxane.

[0182] In some embodiments, the weight-average molecular weight of the polysilsesquioxane can be from 10,000 to 100,000, for example, it can be 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, or any combination of the above values. Optionally, the weight-average molecular weight of the polysilsesquioxane can be 10,000-95,000, 15,000-95,000, 20,000-90,000, 30,000-80,000, 40,000-70,000, or 50,000-60,000.

[0183] When the weight-average molecular weight of polysilsesquioxane is within the above range, polysilsesquioxane with uniform particle size distribution can be obtained, which improves the heat resistance of the separator. In addition, it can reduce the probability of polysilsesquioxane clogging the micropores on the separator, thereby improving the cycle performance of the secondary battery cell.

[0184] The weight-average molecular weight of polysilsesquioxanes can be determined using gel permeation chromatography (GPC) according to GB / T21863-2008. Specifically, it can be performed as follows: using an ultra-high performance polymer chromatograph (UHPLC): ACQUITY APC; detector: ACQUITY differential refractive index detector.

[0185] Parameter settings: Injection volume: 0 μL to 50 μL (depending on sample concentration); Pump flow rate: 0.2 mL / min; Mobile phase: 30 mol / L LiBr in NMP (N-methylpyrrolidone) solution; Sealing and cleaning solution: isopropanol; Pre-column: PLgel 10 μm Mini MIX-B Guard (size: 50 mm × 4.6 mm × 2); Analytical phase: PLgel 10 μm Mini MIX-B (size: 250 mm × 4.6 mm); Standards: polystyrene sleeve; Run time: 30 min; Detector: ACQUITY differential refractive index (RI) detector; Column oven temperature: 90 °C; Detector temperature: 55 °C.

[0186] Sample testing: a. Preparation of standard and test samples: Weigh 0.002g to 0.004g of standard / test sample and add 2mL of mobile phase liquid to prepare a 0.1% to 0.5% mixed standard solution and place it in the refrigerator for >8h; b. Standard solution / sample testing: Edit the sample group to be tested, select the established sample group method, and after the baseline stabilizes, click the run queue to start testing the samples.

[0187] Data processing: Based on the relationship between retention time and molecular weight, a calibration curve is established using a chemical workstation, and the sample spectrum is integrated and quantified. The chemical workstation automatically generates molecular weight and molecular weight distribution results.

[0188] In some embodiments, the structural formula of polysilsesquioxane may include:

[0189] R1 and R2 each independently include an alkyl group with 1-12 carbon atoms, an unsaturated hydrocarbon group with 2-12 carbon atoms, or a phenyl group, n = 50-1000.

[0190] The unsaturated hydrocarbon group can be alkenyl or ynyl.

[0191] Optionally, R1 and R2 each independently include alkyl groups with 2-11 carbon atoms, alkyl groups with 3-10 carbon atoms, alkyl groups with 4-9 carbon atoms, alkyl groups with 5-8 carbon atoms, alkyl groups with 6-7 carbon atoms, etc.

[0192] Optionally, R1 and R2 each independently include an alkenyl or ynyl group with 2-11 carbon atoms, an alkenyl or ynyl group with 3-10 carbon atoms, an alkenyl or ynyl group with 4-9 carbon atoms, an alkenyl or ynyl group with 5-8 carbon atoms, an alkenyl or ynyl group with 6-7 carbon atoms, etc.

[0193] Optionally, n = 50-999, n = 100-950, n = 200-900, n = 300-800, n = 400-700, n = 500-600.

[0194] Therefore, the polysilsesquioxane with the above-mentioned structure improves the heat resistance of the separator. In addition, it can reduce the probability of polysilsesquioxane clogging the micropores on the separator, thereby improving the cycle performance of the secondary battery cell.

[0195] Alternatively, the polysilsesquioxane may include at least one of the following structural formulas:

[0196] Ph represents phenyl, n = 50-1000.

[0197] Optionally, n = 50-999, n = 100-950, n = 200-900, n = 300-800, n = 400-700, n = 500-600, etc. It can be understood that the values ​​of n in the above structural formulas are independent of each other, and can be equal or unequal.

[0198] Therefore, the polysilsesquioxane with the above-mentioned structure improves the heat resistance of the separator. In addition, it can reduce the probability of polysilsesquioxane clogging the micropores on the separator, thereby improving the cycle performance of the secondary battery cell.

[0199] In some embodiments, polysilsesquioxane has no melting point.

[0200] In some embodiments, polysilsesquioxane has no glass transition temperature.

[0201] In some embodiments, the swelling degree of polysilsesquioxane after being immersed at 60°C for 7 days in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 is less than or equal to 3%.

[0202] In some embodiments, the dissolution rate of polysilsesquioxane in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7, after being soaked at 60°C for 7 days, is less than or equal to 3%.

[0203] In some embodiments, the cyclic voltammetry curve of the polysilsesquioxane during the first cycle does not exhibit an oxidation peak in the voltage range of 2.5V to 4.4V.

[0204] Polysilsesquioxanes are commercially available or can be prepared according to the preparation method provided in this disclosure.

[0205] The preparation method of polysilsesquioxane includes the following steps: hydrolyzing the siloxane monomer, adding a catalyst, and polycondensing under heating conditions to obtain polysilsesquioxane.

[0206] In some embodiments, the hydrolysis temperature of the siloxane monomer can be 20°C-30°C. Within this hydrolysis temperature range, the siloxane monomer is fully hydrolyzed, and the resulting polysilsesquioxane, when used in a separator membrane, can improve the cycle performance of the secondary battery cell.

[0207] In some embodiments, the heating temperature can be 30°C-100°C. Within the above heating temperature range, polysilsesquioxane with uniform particle size distribution can be obtained, which can improve the cycle performance of secondary battery cells. Optionally, the heating temperature can be 40°C-80°C.

[0208] Specifically, the siloxane monomer first hydrolyzes to generate silanol, releasing alcohol to form a mixed solution. The alcohol increases the solubility of the siloxane monomer in the solution. Then, under the action of a catalyst, the silanol begins to condense, forming Si-O-Si bonds between silanols, further forming a network structure, at which point nucleation begins. Finally, these nuclei continuously absorb silanol from the solution and continue to grow until they become polysilsesquioxane. The nucleation and nucleus growth processes are competitive, and the reaction temperature affects both processes. When nucleation dominates, more nuclei are generated, resulting in smaller final polysilsesquioxane particle sizes; when nucleus growth dominates, the final microspheres have larger particle sizes. Increasing the temperature intensifies the reaction, generating more nuclei and consuming more silanol in the initial stages, thus limiting nucleus growth in later stages and resulting in smaller final polysilsesquioxane particle sizes. Controlling the heating temperature within the range of 30℃-100℃ can promote uniform polysilsesquioxane particle size and improve the cycle performance of the secondary battery cell.

[0209] In some embodiments, the catalyst may include one or more of ammonia, triethylamine, sodium hydroxide, magnesium hydroxide, and ammonium hydroxide. Therefore, the above catalyst can continuously and efficiently catalyze the polycondensation of hydrolyzed siloxane monomers, yielding polysilsesquioxanes with uniform particle size distribution, thereby improving the cycle performance of secondary battery cells.

[0210] In some embodiments, the siloxane monomer may include:

[0211] R3 includes any one of methyl or ethyl, and R4 includes any one of methyl, ethyl, phenyl, vinyl, allyl, and dodecyl. Therefore, the above-mentioned siloxane monomers can be hydrolyzed and polycondensed to obtain polysilsesquioxanes with uniform particle size distribution, which can improve the cycle performance of secondary battery cells.

[0212] As an example, siloxane monomers may include one or more of methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, dodecyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane, dodecyltriethoxysilane, vinyltriethoxysilane, and allyltriethoxysilane.

[0213] Specifically, taking R3 as methyl and R4 as methyl as an example, the hydrolysis and condensation reaction process of siloxane monomers is as follows:

[0214] In some embodiments, the porous coating includes an adhesive, which may include, but is not limited to, one or more of polyacrylate adhesives, nitrile rubber adhesives, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0215] In some embodiments, the binder may account for 1%-10% of the mass of the porous coating.

[0216] In some embodiments, the porous coating may further include a dispersant, such as, but not limited to, polyacrylic acid dispersants or carboxymethyl cellulose dispersants. As an example, the dispersant may include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0217] In some embodiments, the porous coating may further include polymer binder particles, the volume distribution particle size Dv50 of which may be 6μm-18μm, for example, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, or any range of the above values.

[0218] In some embodiments, polymer binder particles may include aggregates of primary particles.

[0219] In some embodiments, the mass percentage of polymer binder particles in the porous coating can be 5%-30%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any range of the above values.

[0220] In some embodiments, polymer binder particles may be embedded in silicone-containing organic crosslinked resin particles and form protrusions on the surface of the porous coating.

[0221] In other embodiments, the porous coating may include a heat-resistant layer and an adhesive layer, wherein the heat-resistant layer is disposed on the porous base film, the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer or the porous base film, silicon-containing organic crosslinked resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0222] For example, a heat-resistant layer is disposed on a porous base membrane, an adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer away from the porous base membrane, silicon-containing organic crosslinked resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer; or, a heat-resistant layer is disposed on one side of the porous base membrane, an adhesive layer is disposed on at least a portion of the surface of the other side of the porous base membrane, silicon-containing organic crosslinked resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0223] In some embodiments, the adhesive layer further includes an adhesive for bonding polymer adhesive particles. The adhesive may include, but is not limited to, one or more of polyacrylate adhesives, nitrile rubber adhesives, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0224] In some embodiments, the adhesive layer may further include a dispersant and / or a surfactant. The dispersant may include, but is not limited to, polyacrylic acid dispersants or carboxymethyl cellulose dispersants. As an example, the dispersant may include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate. The surfactant may include ether-based surfactants.

[0225] In some embodiments, the polymer binder particles may include one or more of fluoropolymer binder particles and non-fluoropolymer binder particles.

[0226] Optionally, the fluoropolymer binder particles may include vinylidene fluoride polymer particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and comonomer. The comonomer may include at least one of olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers. Optionally, the comonomer may include at least one of the following: trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers (e.g., perfluoro(methyl vinyl) ether, perfluoro(ethyl vinyl) ether, perfluoro(propyl vinyl) ether), perfluoro(1,3-m-dioxacyclopentene), and perfluoro(2,2-dimethyl-1,3-m-dioxacyclopentene).

[0227] Optionally, the non-fluoropolymer binder particles may include acrylate copolymers. Acrylate copolymers are a general term for polymers produced by copolymerization of acrylate monomers and other comonomers.

[0228] Acrylic copolymers have good adhesion, and using acrylic copolymers results in better adhesion between the separator and the electrode sheet after cold or hot pressing.

[0229] In some embodiments, the thickness of the porous coating can be 0.4 μm-5 μm. The thickness of the porous coating refers to the thickness of the porous coating located on one side of the porous base film. Optionally, the thickness of the porous coating can be 0.5 μm-4 μm, 0.5 μm-3 μm, 0.5 μm-2 μm, 0.6 μm-4 μm, 0.6 μm-3 μm, 0.6 μm-2 μm, 0.8 μm-4 μm, 0.8 μm-3 μm, or 0.8 μm-2 μm.

[0230] In some embodiments, the thickness of the separator can be 4.5 μm-14 μm. This is beneficial for improving the energy density of the secondary battery cell.

[0231] In some embodiments, the porosity of the separator can be 25%-60%, optionally 40%-48%.

[0232] The compressive modulus of the separator can be obtained by adjusting one or more of the parameters of the porous coating, such as the morphology, particle size, and content of each component (e.g., silicon-containing organic crosslinked resin particles, polymer binder particles, etc.) and the compressive modulus of the porous base membrane.

[0233] It should be noted that the porous coating parameters of the above-mentioned separator are all the porous coating parameters of one side of the porous base membrane. When the porous coating is disposed on both sides of the porous base membrane, if the porous coating parameters of either side meet the requirements of this disclosure, it is considered to fall within the protection scope of this disclosure.

[0234] This disclosure also provides a method for preparing a separator membrane, which can prepare the separator membrane provided in this disclosure.

[0235] The preparation method of the separator includes the following steps: providing a porous base membrane; providing a slurry comprising silicon-containing organic crosslinked resin particles and a binder; coating the slurry on one or both sides of the porous base membrane; and drying it in an oven to obtain a separator with a compression modulus of 50 MPa-86 MPa.

[0236] In some embodiments, the solvent for the slurry may be water, such as deionized water.

[0237] In some embodiments, the slurry may also include other components, such as dispersants and / or wetting agents.

[0238] In some embodiments, the viscosity of the slurry at 25°C can be 100 mPa·s-300 mPa·s.

[0239] In some embodiments, the solid content of the slurry is 10%-25%.

[0240] In some embodiments, the temperature of the oven can be 50°C-90°C.

[0241] In some embodiments, the drying time of the slurry in the oven can be 10s-40s (seconds).

[0242] In some embodiments, the slurry may further include polymer binder particles, which are embedded in silicon-containing organic crosslinked resin particles and form protrusions on the surface of the porous coating after the slurry is dried in an oven.

[0243] In some embodiments, the method for preparing the separator membrane includes the following steps: coating a slurry comprising silicon-containing organic crosslinked resin particles and a binder onto one or both sides of a porous base membrane, drying it in an oven to form a heat-resistant layer, then coating at least a portion of the surface of the heat-resistant layer with a slurry comprising polymer binder particles and a binder, and then drying it in an oven to obtain the separator membrane.

[0244] In some embodiments, the method for preparing the separator membrane includes the following steps: coating a slurry comprising silicon-containing organic crosslinked resin particles and a binder onto one side of a porous base membrane, coating a slurry comprising polymer binder particles and a binder onto at least a portion of the surface of the other side of the porous base membrane, and drying the membrane in an oven to obtain the separator membrane.

[0245] The secondary battery cells disclosed herein may include, but are not limited to, lithium battery cells, sodium battery cells, etc. The composition of the positive electrode, negative electrode and electrolyte may differ depending on the type of secondary battery cell.

[0246] [Positive electrode plate]

[0247] 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.

[0248] 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 secondary 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.

[0249] 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 0.05 One or more of O2, LiFePO4, and LiMnPO4.

[0250] During the charging and discharging process, Li undergoes insertion / extraction and consumption in a single secondary 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 feeding. As the positive electrode active material is applied to a secondary battery cell, the molar Li content changes after charge-discharge cycles. Similarly, in the examples of positive electrode active materials in this disclosure, the molar O content is only a theoretical value. Lattice oxygen release causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0251] Taking sodium-ion battery cells as an example, the positive electrode active material can be one or more of the following, including but not limited to sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials. For example, the positive electrode active material can be, 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.

[0252] The modified compounds for the positive electrode active materials of the aforementioned lithium battery cells and sodium battery cells can be obtained by doping and / or surface coating modifications of the positive electrode active materials.

[0253] 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.

[0254] 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), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0255] 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 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 aluminum, aluminum 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, and polyethylene.

[0256] 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.

[0257] [Negative electrode plate]

[0258] 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.

[0259] The negative electrode active material may be any material known in the art for use in secondary 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.

[0260] 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.

[0261] 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).

[0262] 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.

[0263] 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, and polyethylene.

[0264] 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.

[0265] 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 a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0266] In some embodiments, the negative electrode sheet can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0267] [Electrolytes]

[0268] A secondary battery cell includes an electrolyte. The electrolyte acts as a conductor of ions between the positive and negative electrodes. In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and an organic solvent.

[0269] 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).

[0270] 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 difluorosulfonyl imide (NaFSI), sodium difluoromethanesulfonyl imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0271] In some embodiments, the organic solvent may include, but is not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), 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), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0272] 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 secondary battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature performance, etc.

[0273] Optionally, the additive may include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), and ethylene sulfate (DTD).

[0274] The preparation methods of secondary 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 secondary battery cell. As an example, the positive electrode, separator, and negative electrode can be wound to form an electrode assembly, which is then placed in an outer package, injected with electrolyte, and subjected to processes such as encapsulation and settling to obtain a secondary battery cell.

[0275] Example

[0276] The following embodiments describe the disclosure of this disclosure in more detail. These embodiments 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 embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0277] Example 1

[0278] Preparation of the separating membrane

[0279] Silicon-containing organic crosslinked resin particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate were mixed evenly in deionized water in a certain proportion to obtain the first slurry. The solid mass ratio of the silicon-containing organic crosslinked resin particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate in the first slurry was 90:2:8.

[0280] Commercially available polyvinylidene fluoride granules (polymer binder particles), polyacrylate binder, sodium carboxymethyl cellulose dispersant, and ether-based surfactants were mixed evenly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain a second slurry.

[0281] A commercially available polyethylene microporous membrane with a thickness of 7 μm, a weight-average molecular weight of 1.3 million, and a compressive modulus of 150 MPa was used as the porous base membrane. A first slurry was coated onto both surfaces of the porous base membrane using a microgravure method. After drying, a second slurry was sprayed onto the membrane, followed by drying and slitting to obtain the separator membrane. In the prepared separator membrane: the silicon-containing organic crosslinked resin particles were spherical with a volume distribution particle size Dv50 of 180 nm; the silicon-containing organic crosslinked resin particles also met the following characteristics: they had a network structure with carbon-carbon bonds as the main chain, side chains containing silicon-oxygen structures, and no melting point or glass transition temperature; the polyvinylidene fluoride particles had a volume distribution particle size Dv50 of 7 μm.

[0282] Preparation of secondary battery cells

[0283] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, positive electrode binder polyvinylidene fluoride (PVDF), and positive electrode conductive agent carbon black are added to N-methylpyrrolidone (NMP) in a mass ratio of 97:2:1 and thoroughly mixed to prepare a positive electrode slurry. The positive electrode slurry is then uniformly coated onto the positive electrode current collector aluminum foil, and subsequently dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0284] Artificial graphite (anode active material), acetylene black (anode conductive agent), styrene-butadiene rubber (SBR) (anode binder), and sodium carboxymethyl cellulose (thickener) were added to deionized water at a mass ratio of 96.0:1.5:1.5:1. After thorough mixing, a cathode slurry was prepared. The cathode slurry was then uniformly coated onto copper foil (anode current collector), and subsequently dried, cold-pressed, and slit to obtain the cathode sheet.

[0285] At 25°C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7 to obtain a mixed solvent. LiPF6, vinylene carbonate (VC), and vinyl sulfate (DTD) were then dissolved in this mixed solvent to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The mass fraction of VC was 2%, and the mass fraction of DTD was 3%, based on the mass of the electrolyte.

[0286] The positive electrode, separator, and negative electrode are stacked, wound, and hot-pressed in sequence to obtain an electrode assembly. The electrode assembly is placed in a hard outer packaging, and the electrolyte prepared above is added. After encapsulation, standing, and formation processes, a secondary battery cell is obtained.

[0287] Example 2

[0288] Except for the following differences, the preparation process of the secondary battery cell is the same as that in Example 1.

[0289] In the prepared separator membrane: the silicon-containing organic crosslinked resin particles have a spherical morphology and a volume distribution particle size Dv50 of 250 nm; the silicon-containing organic crosslinked resin particles also meet the following characteristics: they are a network structure formed by carbon-carbon bonds as the main chain, the side chains contain silicon-oxygen structures, and they have no melting point and no glass transition temperature; the volume distribution particle size Dv50 of polyvinylidene fluoride particles is 8 μm.

[0290] Example 3

[0291] Except for the following differences, the preparation process of the secondary battery cell is the same as that in Example 1.

[0292] In the prepared separator membrane: the silicon-containing organic crosslinked resin particles have a spherical morphology and a volume distribution particle size Dv50 of 330 nm; the silicon-containing organic crosslinked resin particles also meet the following characteristics: they are a network structure formed by carbon-carbon bonds as the main chain, the side chains contain silicon-oxygen structures, and they have no melting point and no glass transition temperature; the volume distribution particle size Dv50 of polyvinylidene fluoride particles is 9 μm.

[0293] Example 4

[0294] Except for the following differences, the preparation process of the secondary battery cell is the same as that in Example 1.

[0295] In the prepared separator membrane: the silicon-containing organic crosslinked resin particles are spherical in shape with a volume distribution particle size Dv50 of 400 nm; the silicon-containing organic crosslinked resin particles also meet the following characteristics: they are a network structure formed with carbon-carbon bonds as the main chain, the side chains contain silicon-oxygen structures, and they have no melting point and no glass transition temperature; the polyvinylidene fluoride particles have a volume distribution particle size Dv50 of 10 μm.

[0296] Comparative Example 1

[0297] Except for the following differences, the preparation process of the secondary battery cell is the same as that in Example 1.

[0298] Preparation of the separating membrane

[0299] Block alumina, sodium carboxymethyl cellulose dispersant, and polyacrylate binder were mixed evenly in deionized water in a certain proportion to obtain the first slurry. The solid mass ratio of alumina, sodium carboxymethyl cellulose dispersant, and polyacrylate binder in the first slurry was 90:2:8.

[0300] Commercially available polyvinylidene fluoride granules (polymer binder particles), polyacrylate binder, sodium carboxymethyl cellulose dispersant, and ether-based surfactants were mixed evenly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain a second slurry.

[0301] A commercially available polyethylene microporous membrane with a thickness of 7 μm, a weight-average molecular weight of 1.3 million, and a compressive modulus of 150 MPa was used as the porous base membrane. A first slurry was coated onto both surfaces of the porous base membrane using a microgravure method. After drying, a second slurry was sprayed onto the membrane, followed by drying and slitting to obtain the separator membrane. In the prepared separator membrane: alumina was in block form with a volume distribution particle size Dv50 of 800 nm; polyvinylidene fluoride particles had a volume distribution particle size Dv50 of 7 μm.

[0302] Performance testing

[0303] (1) Compression modulus test of porous base membrane and separator membrane

[0304] The test method for the compressive modulus of the separator is as follows:

[0305] Sample pretreatment: Cut the release film with a die, stacking order: die / white paper / release film / white paper / pressing block, cut 5 layers at a time, 100 layers as a group, make 3 parallel samples, sample size 60mm*70mm; cut the aluminum-plastic film with a size of 90mm*200mm with a guillotine cutter; fold the aluminum-plastic film in half along its length; fix the center position of the four sides of the cut release film sample with green glue and place it in a Pocket bag; use a top-side sealing machine to seal the two long sides of the sample, then vacuum seal the top, the sealing machine heating temperature is 185℃; place a pad in the center position of the sealed sample and mark the frame; 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.

[0306] Sample testing: Turn on the IEST SWE2110 in-situ expansion analyzer, open the MISS operating software, and perform pressure calibration; select compression test (transient), and thickness calibration; 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; click MISS in the software to start the experiment. After the test is completed, measure the sample thickness M1, and mark the clamp indentation positions on the upper and lower sides of the sample with a marker; repeat the operation to perform the test again.

[0307] Data processing: Plot a stress-strain curve with strain on the x-axis and stress on the y-axis; perform linear fitting of the stress / strain curve from 3MPa to 5MPa to obtain the compressive modulus of the isolation membrane. Strain = Deformation / Initial sample thickness, Deformation = Initial sample thickness - Real-time sample thickness.

[0308] The test method for the compressive modulus of porous base membranes can refer to the test method for the compressive modulus of separator membranes.

[0309] (2) Thermal shrinkage rate test of the separator film

[0310] The heat shrinkage rate test of the release liner can be referenced in GB / T 36363-2018. An example can be found by following these steps:

[0311] Cut the release film into samples with a width of 50mm and a length of 100mm using a punching machine. Take 5 parallel samples and place them on A4 paper. Then place the A4 paper containing the samples on corrugated paper with a thickness of 1mm to 5mm.

[0312] Set the temperature of the forced-air drying oven to 130℃. After the temperature reaches the set temperature and stabilizes for 60 minutes, place the A4 paper placed on the corrugated paper into the forced-air drying oven and start timing. After the set time (1 hour in this disclosure) is reached, measure the length and width of the isolation film, and mark the values ​​as a and b respectively.

[0313] Calculation of heat shrinkage rate: Longitudinal (MD) heat shrinkage rate = [(100-a) / 100]×100%, Transverse (TD) heat shrinkage rate = [(50-b) / 50]×100%, take the average value of 3 parallel samples as the test result.

[0314] (3) Voltage breakdown strength test of the separator

[0315] The voltage breakdown strength test of the separator can be referenced in GB / T 13542.2-2009 and GB / T 1408-2006.

[0316] The release diaphragm was cut into rectangular samples of 450mm × 650mm and tested using a pressure resistance tester. The test instrument used was a CS2671AX pressure resistance tester.

[0317] (4) Cycle performance test of secondary battery cells

[0318] At 45℃, a single secondary battery cell is charged to 4.25V at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 4.25V, left to rest for 5 minutes, and then discharged to 2.8V at a constant current of 1 / 3C. The resulting discharge capacity is recorded as the initial capacity C0. This charging and discharging process is repeated, and the discharge capacity Cn of the single secondary battery cell after the nth cycle is recorded. The capacity retention rate of the single secondary battery cell after each cycle is Pn = (Cn / C0) × 100%. The capacity retention rate of the single secondary battery cell after 500 cycles can be used to reflect the difference in cycle performance of the single secondary battery cell.

[0319] Table 1

[0320] As can be seen from the above test results, the separator of this disclosure uses specific silicon-containing organic cross-linked resin particles and controls the compression modulus of the separator within a specific range. This allows the separator to effectively improve the voltage breakdown strength of the separator and the cycle capacity retention rate of the secondary battery cells, while ensuring high heat resistance and high energy density of the secondary battery cells.

[0321] 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. A secondary battery cell, comprising an electrode assembly, the electrode assembly including a positive electrode, a negative electrode, and a separator, the separator being disposed between the positive electrode and the negative electrode, wherein, The separator includes a porous base membrane and a porous coating located on one or both sides of the porous base membrane. The porous coating includes silicon-containing organic crosslinked resin particles, and the compressive modulus of the separator is 50 MPa-86 MPa.

2. The secondary battery cell according to claim 1, wherein, The compression modulus of the separator is 65MPa-81MPa.

3. The secondary battery cell according to any one of claims 1-2, wherein, The compressive modulus of the porous base membrane is 100MPa-300MPa.

4. The secondary battery cell according to any one of claims 1-3, wherein, The average pore size of the porous base film is 25nm-80nm; and / or, The porosity of the porous base membrane is 25%-60%, optionally 30%-50%; and / or, The thickness of the porous base film is 3μm-11μm, and can be selected as 3μm-7μm.

5. The secondary battery cell according to any one of claims 1-4, wherein, The porous base membrane is made of polyethylene, and the weight-average molecular weight of the polyethylene is 600,000 to 2,000,000; or, The porous base membrane is made of polypropylene, and the weight-average molecular weight of the polypropylene is 400,000 to 800,000.

6. The secondary battery cell according to any one of claims 1-5, wherein, The morphology of the silicon-containing organic crosslinked resin particles includes one or more of the following: spherical, near-spherical, ellipsoidal, and near-ellipsoidal; and / or, The volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles is less than 1 μm, and can be selected as 60 nm-800 nm; and / or, The particle size distribution (Dv90-Dv10) / Dv50 of the silicon-containing organic crosslinked resin particles is 0.2-1.

1.

7. The secondary battery cell according to any one of claims 1-6, wherein, The true density of the silicon-containing organic cross-linked resin particles is 1.0 g / cm³. 3 -1.5g / cm 3 .

8. The secondary battery cell according to any one of claims 1-7, wherein, The porous coating also includes polymer binder particles, the volume distribution particle size Dv50 of which is 6μm-18μm.

9. The secondary battery cell according to claim 8, wherein, The polymer binder particles include one or more of fluoropolymer binder particles and non-fluoropolymer binder particles; and / or, The polymer binder particles comprise aggregates of primary particles.

10. The secondary battery cell according to any one of claims 8-9, wherein, The polymer binder particles account for 5%-30% of the mass of the porous coating.

11. The secondary battery cell according to any one of claims 8-10, wherein, The polymer binder particles are embedded in the silicon-containing organic crosslinked resin particles and form protrusions on the surface of the porous coating.

12. The secondary battery cell according to any one of claims 8-10, wherein, The porous coating includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on the porous base film, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer or the porous base film. The silicon-containing organic crosslinked resin particles are disposed in the heat-resistant layer, and the polymer adhesive particles are disposed in the adhesive layer.

13. The secondary battery cell according to any one of claims 1-12, wherein, The thickness of the porous coating is 0.4 μm-5 μm; and / or, The total thickness of the isolation membrane is 4.5 μm-14 μm; and / or, The porosity of the isolation membrane is 25%-60%, and optionally 40%-48%.

14. The secondary battery cell according to any one of claims 1-13, wherein, The ratio of the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles to the average pore size of the porous base membrane is greater than or equal to 1.

2.

15. The secondary battery cell according to any one of claims 1-14, wherein, The silicon-containing organic crosslinked resin particles satisfy one or more of the following conditions (1) to (5): (1) The silicon-containing organic crosslinked resin particles have no melting point; (2) The silicon-containing organic crosslinked resin particles have no glass transition temperature; (3) The swelling degree of the silicon-containing organic crosslinked resin particles after being soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%. (4) The dissolution rate of the silicon-containing organic crosslinked resin particles after being soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%. (5) The cyclic voltammetry curve of the silicon-containing organic crosslinked resin particles in the first cycle does not have an oxidation peak in the voltage range of 2.5V to 4.4V.

16. The secondary battery cell according to any one of claims 1-15, wherein, The silicon-containing organic crosslinked resin particles contain carbon-carbon bonds and silicon-oxygen structures.

17. The secondary battery cell according to claim 16, wherein, The silicon-containing organic crosslinked resin particles have a network structure with carbon-carbon bonds as the main chain and silicon-oxygen structures in the side chains.

18. The secondary battery cell according to claim 17, wherein, The silicon-containing organic crosslinked resin particles have a network structure with carbon-carbon bonds as the main chain and side chains containing silicon-oxygen structures and benzene ring structures.

19. The secondary battery cell according to any one of claims 16-18, wherein, The silicon-containing organic crosslinked resin particles comprise crosslinked structural units, including divinylbenzene structural units, diethylene glycol divinyl ether structural units, triethylene glycol divinyl ether structural units, diallyl maleate structural units, ethylene glycol dimethacrylate structural units, 1,4-butanediol diacrylate structural units, 1,6-hexanediol diacrylate structural units, 1,8-octanediol diacrylate structural units, trimethylolpropane triacrylate structural units, pentaerythritol trimethacrylate structural units, and tetraethylene glycol dimethylpropene. One or more of the following structural units: ester, dipropylene glycol diacrylate, 2,2,4-trimethyladhexanoyl di[2-ethylaziridinium], 1,1-azeloyl di[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl) di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

20. The secondary battery cell according to any one of claims 1-15, wherein, The silicon-containing organic crosslinked resin particles comprise polysilsesquioxane, and the polysilsesquioxane satisfies one or both of the following conditions (1) to (2): (1) The weight-average molecular weight of the polysilsesquioxane is 10,000 to 100,000; (2) The structural formula of the polysilsesquioxane includes: R1 and R2 each independently include an alkyl group with 1-12 carbon atoms, an unsaturated hydrocarbon group with 2-12 carbon atoms, or a phenyl group, n = 50-1000.

21. The secondary battery cell according to claim 20, wherein, The polysilsesquioxane comprises at least one of the following structural formulas: Ph represents phenyl, n = 50-1000.

22. A battery device comprising a plurality of secondary battery cells as described in any one of claims 1-21.

23. An electrical device comprising a secondary battery cell as described in any one of claims 1-21 or a battery device as described in claim 22.

24. A separating membrane, wherein, The separator includes a porous base membrane and a porous coating located on one or both sides of the porous base membrane. The porous coating includes silicon-containing organic crosslinked resin particles, and the compressive modulus of the separator is 50 MPa-86 MPa.

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