Isolating membrane and preparation method thereof, secondary battery monomer, battery device and power utilization device

Abstract

The invention provides an isolating membrane and a preparation method thereof, a secondary battery monomer, a battery device and a power utilization device, the isolating membrane comprises a porous base membrane and a porous coating positioned on at least one side of the porous base membrane, the porous coating comprises silicon-containing organic resin particles and fibrous materials, and at least part of the silicon-containing organic resin particles are positioned among the fibrous materials. The isolating membrane is used in the secondary battery monomer, so that the secondary battery monomer has high mass energy density and high reliability.

Description

Technical Field

[0001] This disclosure relates to a separator membrane and its preparation method, a secondary battery cell, a battery device, and an electrical device. Background Technology

[0002] As the application range of rechargeable battery cells becomes increasingly widespread, the demands on them are also growing, with higher requirements for energy density and reliability. Therefore, how to achieve higher energy density in rechargeable battery cells while maintaining high reliability is a pressing technical problem that needs to be solved. Summary of the Invention

[0003] This disclosure provides a separator and its preparation method, a secondary battery cell, a battery device, and an electrical device. The separator, when used in a secondary battery cell, enables the secondary battery cell to have both high energy density and high reliability.

[0004] In a first aspect, this disclosure provides a separator membrane, the separator membrane comprising a porous base membrane and a porous coating located on at least one side of the porous base membrane, the porous coating comprising silicon-containing organic resin particles and fibrous materials, and at least a portion of the silicon-containing organic resin particles being located between the fibrous materials.

[0005] The low density of silicon-containing organic resin particles and fibrous materials allows for higher gravimetric energy density in secondary battery cells. The porous coating of the separator disclosed herein comprises a mixture of silicon-containing organic resin particles and fibrous materials. The introduction of the fibrous materials connects and disperses the silicon-containing organic resin particles, thereby improving the overall structure and heat resistance of the porous coating, reducing overall thermal shrinkage of the separator, and enhancing the reliability of the secondary battery cell. Therefore, the separator of this disclosure enables secondary battery cells to possess both high gravimetric energy density and high reliability.

[0006] In some embodiments, the silicon-containing organic resin particles have no glass transition temperature below 300°C. The fact that the silicon-containing organic resin particles have no glass transition temperature below 300°C 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.

[0007] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, which contain carbon-carbon bonds and silicon-oxygen structures.

[0008] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, wherein the silicon-containing organic 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.

[0009] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, and the silicon-containing organic cross-linked resin particles include cross-linked structural units.

[0010] Optionally, the crosslinked structural units 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.

[0011] In some embodiments, the silicon-containing organic resin particles have no melting point. The absence of a melting point in the silicon-containing organic 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.

[0012] In some embodiments, the dissolution rate of the silicon-containing organic resin particles after being immersed 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 resin particles in organic solvents results in higher structural stability during long-term use of the secondary battery cell and higher chemical stability in the electrolyte, thereby enabling the secondary battery cell to have longer cycle stability.

[0013] In some embodiments, the swelling degree of the silicon-containing organic 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 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.

[0014] In some embodiments, the cyclic voltammetry curve of the silicon-containing organic resin particles in the first cycle does not exhibit an oxidation peak within a voltage range of 2.50V to 4.40V. The absence of an oxidation peak in the cyclic voltammetry curve of the silicon-containing organic resin particles in the first cycle within this voltage range indicates that the silicon-containing organic resin particles are stable within this voltage range. Therefore, the silicon-containing organic resin particles of this disclosure possess good electrochemical stability and can be applied to high-voltage secondary battery cells to improve the operating voltage and energy density of the secondary battery cells, and also enable the secondary battery cells to exhibit good capacity performance characteristics under high voltage.

[0015] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin particles is 80nm-800nm.

[0016] The volume distribution particle size Dv50 of the silicon-containing organic resin particles is within the above range, which is beneficial for the porous coating of the separator to have good heat resistance and air permeability.

[0017] In some embodiments, the true density of the silicon-containing organic resin particles is 1.1 g / cm³. 3 -1.5g / cm 3 .

[0018] In some embodiments, the diameter of the fibrous material ranges from 10 nm to 200 nm.

[0019] In some embodiments, the length of the fibrous material ranges from 0.15 μm to 30 μm.

[0020] The length of the fibrous material is within the above range, which can better connect the silicon-containing organic resin particles, improve the overall structure and heat resistance of the porous coating, reduce the overall thermal shrinkage of the separator, and improve the air permeability of the separator.

[0021] In some embodiments, the fibrous material includes one or more of glyco-based fibers, protein-based fibers, polymer fibers, and inorganic fibers.

[0022] In some embodiments, the fibrous material includes one or more of the following: alginate and its derivative fibers, nanocellulose and its derivative fibers, chitosan and its derivative fibers, chitin and its derivative fibers, plant cellulose, silk protein fibers, spider silk protein fibers, corn protein fibers, soybean protein fibers, keratin fibers, wool fibers, cashmere fibers, aramid fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyethylene fibers, ultra-high molecular weight polyethylene fibers, polypropylene fibers, polytetrafluoroethylene fibers, polyvinylidene fluoride fibers, polyurethane fibers, acetate fibers, polycaprolactone fibers, polylactic acid fibers, polyethersulfone fibers, acrylic fibers, acrylic polymer fibers, polymethyl methacrylate fibers, poly(2-hydroxyethyl methacrylate) fibers, polyethylene phthalate fibers, polyethylene terephthalate fibers, p-phenylenediamine terephthalate fibers, glass fibers, asbestos fibers, and silica fibers.

[0023] In some embodiments, the fibrous material has polar groups.

[0024] Optionally, the polar group includes one or more of the following: hydroxyl, carboxyl, ester, amide, cyano, amino, aldehyde, sulfonic acid, boric acid, and phosphate.

[0025] The fibrous material has polar groups, which can generate stronger interactions with the binder in the porous coating, such as forming hydrogen bonds or ionic bonds, making the adhesion between the porous coating and the porous base film stronger, thereby improving the overall structure of the separator and the heat resistance of the separator.

[0026] In some embodiments, the mass content of the silicon-containing organic resin particles in the porous coating is greater than or equal to 55% based on the total mass of the porous coating.

[0027] In some embodiments, the mass content of fibrous material in the porous coating is 0.3%-30% based on the total mass of the porous coating. A mass content of fibrous material within this range allows the separator to possess both good heat resistance and air permeability, thereby enabling the secondary battery cell to have high reliability and good cycle performance.

[0028] In some embodiments, the porous coating further includes an adhesive.

[0029] In some embodiments, the thickness of the porous coating is 0.5 μm-5 μm.

[0030] In a second aspect, this disclosure provides a method for preparing a separator membrane according to the first aspect, comprising the following steps: providing a porous base membrane; providing a slurry comprising silicone organic resin particles, fibrous material, and binder; coating the slurry onto at least one side of the porous base membrane, and drying it to obtain a separator membrane.

[0031] In some embodiments, a method for providing silicone-containing organic resin particles includes the following steps: providing a pre-emulsion comprising a monomer, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomer comprises a silane coupling agent containing an alkenyl group and / or an acryloyloxy group; and subjecting the pre-emulsion to an emulsion polymerization reaction under heating, inert gas protection, and stirring conditions to obtain silicone-containing organic resin particles.

[0032] In some embodiments, the method further includes the steps of: drying the product obtained from the emulsion polymerization reaction, and then subjecting it to a crushing process and a wet grinding process to obtain silicon-containing organic resin particles.

[0033] In some embodiments, the method further includes the steps of: drying the product obtained by emulsion polymerization, baking it under an inert gas atmosphere, and then crushing and wet grinding it to obtain silicon-containing organic resin particles.

[0034] In some embodiments, the monomer includes 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, ethylene One or more of the following: tri(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.

[0035] In some embodiments, the crosslinking agent includes one or more of 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-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.

[0036] In some embodiments, the mass fraction of the crosslinking agent is 1.5%-18% based on the total mass of the monomer and the crosslinking agent being 100%.

[0037] In some embodiments, the emulsion polymerization reaction includes the following steps: under a first temperature, inert gas protection and stirring conditions, the pre-emulsion is dropwise added to a reactor containing water, and after a first reaction time, the temperature is raised to a second temperature to mature the reaction for a second time to obtain silicon-containing organic resin particles.

[0038] In some embodiments, the first temperature is 55°C-70°C.

[0039] In some embodiments, the first time is 3h-6h.

[0040] In some embodiments, the second temperature is 72°C-92°C.

[0041] In some embodiments, the second time is 1 hour to 5 hours.

[0042] In some embodiments, the inert gas includes one or more of nitrogen, argon, and helium.

[0043] Thirdly, this disclosure provides a secondary battery cell, which includes a positive electrode, a negative electrode, and a separator according to the first aspect of this disclosure, wherein the separator is disposed between the positive electrode and the negative electrode.

[0044] Fourthly, this disclosure provides a battery device comprising a plurality of secondary battery cells according to the third aspect of this disclosure.

[0045] Fifthly, this disclosure provides an electrical device that includes a secondary battery cell according to the third aspect of this disclosure or a battery device according to the fourth aspect. 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 A schematic diagram of a secondary battery cell provided in some embodiments of this disclosure is shown.

[0048] Figure 2 A schematic diagram of an electrical device provided in some embodiments of this disclosure is shown. Detailed Implementation

[0049] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the separator, its preparation method, secondary battery cell, battery device, and power supply device 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.

[0050] 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.

[0051] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0056] 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.

[0057] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0058] The secondary battery cell mentioned in the embodiments of this disclosure can independently perform charge and discharge functions. After discharge, it can be reactivated by charging to allow for continued use. The secondary battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this disclosure are not limited in this regard. Figure 1 The example is a cuboid-structured secondary battery cell 5.

[0059] 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.

[0060] The secondary battery cell provided in the embodiments of this disclosure includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this disclosure are not limited in this regard. The secondary battery cell also includes an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0061] 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.

[0062] In some embodiments, a battery cell assembly is typically formed by arranging multiple secondary battery cells.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple secondary battery cells to the housing.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Figure 2 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0072] In the context of this disclosure, the "silicon-containing organic resin particles" primarily serve to improve heat resistance in the porous coating of the separator, and they have almost no adhesive properties.

[0073] The separator is a crucial component supporting the electrochemical processes of charging and discharging in a secondary battery cell. Commonly used separators are often made of polyolefins; however, polyolefins have poor heat resistance and are prone to softening or melting at high temperatures, which can lead to short circuits in the secondary battery cells. To improve the heat resistance of the separator, a porous coating is typically applied. Boehmite, alumina, and other inorganic particles are commonly used heat-resistant fillers; however, these fillers have high density and a large mass for the same bulk volume, thus affecting the energy density of the secondary battery cells.

[0074] Based on this, the present disclosure provides a separator membrane for use in secondary battery cells, which enables secondary battery cells to have both high energy density and high reliability.

[0075] The separator disclosed herein includes a porous base membrane and a porous coating located on at least one side of the porous base membrane. The porous coating includes silicon-containing organic resin particles and fibrous materials, and at least a portion of the silicon-containing organic resin particles are located between the fibrous materials.

[0076] Both the porous base membrane and the porous coating have a porous structure, which gives the separator good air permeability and facilitates the passage of ions.

[0077] Silicon-containing organic resin particles and fibrous materials have low density, which allows secondary battery cells using them to have higher mass energy density.

[0078] Silicone-containing organic resin particles, when used alone, do not exhibit excellent heat resistance. While fibrous materials possess high strength, high heat resistance, and low thermal shrinkage, their small diameter, when used alone in separators, reduces the membrane's permeability. The porous coating for separators disclosed herein comprises a mixture of silicone-containing organic resin particles and fibrous materials. The introduction of the fibrous material connects and disperses the silicone-containing organic resin particles, thereby improving the overall structure and heat resistance of the porous coating. This reduces the overall thermal shrinkage of the separator and enhances the reliability of the secondary battery cells.

[0079] Therefore, the separator disclosed herein enables secondary battery cells to possess both high energy density and high reliability.

[0080] The silicon-containing organic resin particles disclosed herein 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 the silicon-containing organic resin particles cannot be determined by gel permeation chromatography.

[0081] In some embodiments, the true density of the silicone-containing organic resin particles can be 1.1 g / cm³. 3 -1.5g / cm 3 .

[0082] 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 resin particles disclosed herein have a low true density, thereby enabling secondary battery cells using the separator of this disclosure to have a higher mass energy density.

[0083] In some embodiments, the silicone-containing organic resin particles have no glass transition temperature below 300°C.

[0084] Silicon-containing organic resin particles have no glass transition temperature below 300℃, indicating good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of porous base films, improve the heat resistance of separators, and enhance the reliability of secondary battery cells.

[0085] Glass transition temperature T gThe 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 DSC curve is used to determine whether the silicon-containing organic resin particles have a glass transition temperature T below 300℃. g .

[0086] Glass transition temperature T g It refers to the transition temperature from the glassy state to the elastic state, which shows a step-like change on the DSC curve.

[0087] Silicon-containing organic resin particles have no glass transition temperature T below 300℃ g This means that the DSC curve of the silicon-containing organic resin particles does not show a step-like change in the range below 300℃.

[0088] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, which contain carbon-carbon bonds and silicon-oxygen structures.

[0089] Optionally, the silicon-containing organic resin particles have a network structure with carbon-carbon bonds as the main chain and silicon-oxygen structures in the side chains.

[0090] Optionally, the silicon-containing organic 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.

[0091] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, and the silicon-containing organic cross-linked resin particles include cross-linked structural units.

[0092] Optionally, the crosslinking structural unit may include a divinylbenzene structural unit, a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a diallyl maleate structural unit, an ethylene glycol dimethacrylate structural unit, a 1,4-butanediol diacrylate structural unit, a 1,6-hexanediol diacrylate structural unit, a 1,8-octanediol diacrylate structural unit, a trimethylolpropane triacrylate structural unit, a pentaerythritol trimethacrylate structural unit, a tetraethylene glycol dimethacrylate structural unit, and a diethylene glycol dimethacrylate structural unit. 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.

[0093] In some embodiments, the silicone-containing organic resin particles have no melting point.

[0094] The silicon-containing organic resin particles disclosed herein have no melting point, indicating that they have good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of porous base films, improve the heat resistance of separators, and enhance the reliability of secondary battery cells.

[0095] 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 resin particles have a melting point below 300℃. Silicon-containing organic resin particles having no melting point means that the DSC curve of the silicon-containing organic resin particles does not show a melting peak.

[0096] In some embodiments, the dissolution rate of silicone-containing organic resin particles 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 can be less than or equal to 3%.

[0097] Silicon-containing organic 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.

[0098] The dissolution rate of silicon-containing organic 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. 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.

[0099] In some embodiments, the swelling degree of silicone-containing organic resin particles 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 can be less than or equal to 3%.

[0100] Silicon-containing organic 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.

[0101] The swelling degree of silicon-containing organic 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. After immersion, remove the sample bag and then remove the sample from the bag. Wipe away 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.

[0102] In some embodiments, the cyclic voltammetry curve of the silicon-containing organic resin particles during the first cycle does not have an oxidation peak in the voltage range of 2.50V to 4.40V.

[0103] The cyclic voltammetry curve of the silicon-containing organic resin particles in the first cycle shows no oxidation peak in the voltage range of 2.50V to 4.40V, indicating that the silicon-containing organic resin particles are stable in this voltage range. Therefore, the silicon-containing organic resin particles disclosed herein exhibit good electrochemical stability and can be applied to high-voltage secondary battery cells to improve the operating voltage and energy density of the secondary battery cells, and also enable the secondary battery cells to have good capacity performance characteristics under high voltage.

[0104] The oxidation peak potential of the cyclic voltammetry curve of silicon-containing organic resin particles can be tested as follows: Silicon-containing organic resin particles, binder polymethyl methacrylate, and conductive carbon black are dissolved in water at a solid-to-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.

[0105] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin particles can be 80nm-800nm.

[0106] The volume distribution particle size Dv50 of the silicon-containing organic resin particles is within the above range, which is beneficial for the porous coating of the separator to have good heat resistance and air permeability.

[0107] Dv50 represents the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material. It can be measured using a laser particle size analyzer, referring to GB / T19077-2016. During testing, add 1g of the sample to a clean small beaker, along with 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, then 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.

[0108] In some embodiments, the diameter of the fibrous material can range from 10 nm to 200 nm.

[0109] Optionally, the diameter range of the fibrous material can be 10nm-160nm, 12nm-160nm, 14nm-160nm, 16nm-160nm, 18nm-160nm, 20nm-160nm, 10nm-120nm, 12nm-120nm, 14nm-120nm, 16nm-120nm, 18nm-120nm, 20nm-120nm, 10nm-100nm. nm, 12nm-100nm, 14nm-100nm, 16nm-100nm, 18nm-100nm, 20nm-100nm, 10nm-80nm, 12nm-80nm, 1 4nm-80nm, 16nm-80nm, 18nm-80nm, 20nm-80nm, 14nm-50nm, 16nm-50nm, 18nm-50nm, 20nm-50nm.

[0110] In some embodiments, the length of the fibrous material can range from 0.15 μm to 30 μm.

[0111] Optionally, the length range of the fibrous material can be 0.3μm-20μm, 0.4μm-20μm, 0.5μm-20μm, 0.6μm-20μm, 0.8μm-20μm, 0.3μm-15μm, 0.4μm-15μm, 0.5μm-15μm, 0.6μm-15μm, 0.8μm-15μm, 0.3μm-10μm, 0.4μm-10μm, 0.5μm-10μm, 0.6μm- 10μm, 0.8μm-10μm, 0.3μm-8μm, 0.4μm-8μm, 0.5μm-8μm, 0.6μm-8μm, 0.8μm-8μm, 0.3μm-5μm, 0.4μm-5 μm, 0.5μm-5μm, 0.6μm-5μm, 0.8μm-5μm, 0.3μm-4μm, 0.4μm-4μm, 0.5μm-4μm, 0.6μm-4μm, 0.8μm-4μm.

[0112] The length of the fibrous material is within the above range, which can better connect the silicon-containing organic resin particles, improve the overall structure and heat resistance of the porous coating, reduce the overall thermal shrinkage of the separator, and improve the air permeability of the separator.

[0113] In some embodiments, fibrous materials may include one or more of sugar-based fibers, protein-based fibers, polymer fibers, and inorganic fibers.

[0114] In some embodiments, the fibrous material may include one or more of the following: alginate and its derivative fibers, nanocellulose and its derivative fibers, chitosan and its derivative fibers, chitin and its derivative fibers, plant cellulose, silk protein fibers, spider silk protein fibers, corn protein fibers, soybean protein fibers, keratin fibers, wool fibers, cashmere fibers, aramid fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyethylene fibers, ultra-high molecular weight polyethylene fibers, polypropylene fibers, polytetrafluoroethylene fibers, polyvinylidene fluoride fibers, polyurethane fibers, acetate fibers, polycaprolactone fibers, polylactic acid fibers, polyethersulfone fibers, acrylic fibers, acrylic polymer fibers, polymethyl methacrylate fibers, poly(2-hydroxyethyl methacrylate) fibers, polyethylene phthalate fibers, polyethylene terephthalate fibers, p-phenylenediamine terephthalate fibers, glass fibers, asbestos fibers, and silica fibers.

[0115] Optionally, alginate and its derivative fibers may include one or more of alginate fibers, alginate fibers, and other chemically modified alginate derivative fibers.

[0116] Optionally, nanocellulose and its derivative fibers may include one or more of nanocellulose fibers, carboxymethyl cellulose fibers, carboxyethyl cellulose fibers, sulfonated cellulose fibers, hydroxymethyl cellulose fibers, hydroxyethyl cellulose fibers, hydroxypropyl cellulose fibers, oxidized cellulose fibers, and other chemically modified cellulose derivative fibers.

[0117] Optionally, chitosan and its derivative fibers may include one or more of the following: chitosan fibers, carboxymethyl chitosan fibers, carboxyethyl chitosan fibers, hydroxypropyl chitosan fibers, hydroxyethyl chitosan fibers, sulfonated chitosan fibers, succinyl chitosan fibers, acetylated chitosan fibers, propionyl chitosan fibers, butyryl chitosan fibers, chitin fibers, and other chemically modified chitosan derivative fibers.

[0118] Optionally, chitin and its derivative fibers may include one or more of chitin fibers, carboxymethyl chitin fibers, carboxyethyl chitin fibers, sulfonated chitin fibers, acetylated chitin fibers, and other chemically modified chitin derivative fibers.

[0119] Plant cellulose refers to cellulose obtained from cellulose-rich plants. Optionally, plant cellulose may include one or more of bamboo cellulose, cotton cellulose, lignocellulose, herbaceous plant cellulose, bagasse cellulose, and flax cellulose.

[0120] In some embodiments, the fibrous material may have polar groups.

[0121] Optionally, the polar group may include one or more of the following: hydroxyl, carboxyl, ester, amide, cyano, amino, aldehyde, sulfonic acid, boric acid, and phosphate.

[0122] The fibrous material has polar groups, which can generate stronger interactions with the binder in the porous coating, such as forming hydrogen bonds or ionic bonds, making the adhesion between the porous coating and the porous base film stronger, thereby improving the overall structure of the separator and the heat resistance of the separator.

[0123] In some embodiments, the mass content of silicon-containing organic resin particles in the porous coating may be greater than or equal to 55% based on the total mass of the porous coating. Optionally, the mass content of silicon-containing organic resin particles in the porous coating may be greater than or equal to 60%, greater than or equal to 65%, greater than or equal to 70%, greater than or equal to 75%, or greater than or equal to 80%.

[0124] In some embodiments, the mass content of fibrous material in the porous coating, based on the total mass of the porous coating, can be 0.3%-30%, for example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or any range of the above values.

[0125] Optionally, the mass content of the fibrous material in the porous coating can be 0.3%-20%, 0.3%-15%, 0.3%-10%, 0.3%-8%, 0.3%-6%, 0.3%-4%, 0.5%-20%, 0.5%-15%, 0.5%-10%, 0.5%-8%, 0.5%-6%, or 0.5%-4%.

[0126] When the mass content of fibrous material is within the above range, the separator can have both good heat resistance and air permeability, thereby enabling the secondary battery cell to have high reliability and good cycle performance.

[0127] 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).

[0128] In some embodiments, the mass content of the binder in the porous coating, based on the total mass of the porous coating, can be 0.5%-10%, for example, it can be 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or any range of the above values. Optionally, the mass content of the binder in the porous coating can be 1%-8%.

[0129] In some embodiments, the porous coating may further include a dispersant, such as one or more of alkylphenol polyoxyethylene ethers, polyacrylic acid dispersants, and cellulose dispersants, including but not limited to. As an example, the dispersant may include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0130] In some embodiments, the separator may also include polymer binder particles.

[0131] The "polymer binder particles" in the porous coating of the separator membrane play a role in improving the adhesion between the separator membrane and the electrode, but they have virtually no heat resistance.

[0132] In some embodiments, polymer binder particles may be embedded in silicone-containing organic resin particles and fibrous materials and form protrusions on the porous coating surface.

[0133] In other embodiments, the porous coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on the porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer on the side away from the porous base membrane. Silicone organic resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0134] In some other embodiments, the porous coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on one side of the porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the other side of the porous base membrane. Silicone organic resin particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0135] In some embodiments, the average particle size of the polymer binder particles can be 6 μm-18 μm.

[0136] In some embodiments, the polymer binder particles may include vinylidene fluoride polymer particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and comonomer.

[0137] Comonomers may include at least one of olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers.

[0138] Optionally, the comonomer may include at least one of the following: trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ether (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).

[0139] In some embodiments, the thickness of the porous coating can be 0.5 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, 0.8 μm-4 μm, 0.8 μm-3 μm, or 0.8 μm-2 μm.

[0140] In some embodiments, the porous base membrane may comprise a membrane or nonwoven web selected from any one or at least two of the following: polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, and polyvinylnaphthalene.

[0141] Porous base membranes can be single-layer thin films or multi-layer composite thin films. When a porous base membrane is a multi-layer composite thin film, the materials of each layer can be the same or different.

[0142] In some embodiments, the thickness of the porous base film can be 4μm-12μm, and optionally 4μm-9μm.

[0143] In some embodiments, the porosity of the porous base membrane can be 25%-60%, optionally 28%-50%.

[0144] In some embodiments, the thickness of the separator can be 5μm-14μm, optionally 5μm-12μm or 6μm-12μm. This is beneficial for improving the energy density of the secondary battery cell.

[0145] 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.

[0146] This disclosure also provides a method for preparing a separator membrane, which can prepare the separator membrane provided in this disclosure.

[0147] The method for preparing the separator membrane includes the following steps: providing a porous base membrane; providing a slurry comprising silicone organic resin particles, fibrous material, and binder; coating the slurry onto at least one side of the porous base membrane, and drying to obtain the separator membrane.

[0148] In some embodiments, the slurry may further include polymer binder particles, which, after drying, are embedded in silicone-containing organic resin particles and fibrous materials, forming protrusions on the porous coating surface.

[0149] In some embodiments, the method for preparing the separator membrane may include: coating a heat-resistant layer slurry comprising silicone organic resin particles and a binder onto at least one side of a porous base membrane, and drying it to form a heat-resistant layer; and coating an adhesive layer slurry comprising polymer binder particles and a binder onto at least a portion of the surface of the heat-resistant layer, and drying it to obtain the separator membrane.

[0150] In some embodiments, the method for preparing the separator membrane may include: coating a heat-resistant slurry comprising silicone organic resin particles and a binder onto one side of a porous base membrane, and coating an adhesive layer 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 slurry to obtain the separator membrane.

[0151] In some embodiments, the solvent for the slurry may be water, such as deionized water.

[0152] In some embodiments, the slurry may also include other components, such as dispersants and / or wetting agents.

[0153] In some embodiments, a method for providing silicone-containing organic resin particles may include the following steps: providing a pre-emulsion comprising monomers, crosslinking agents, emulsifiers, initiators, and water, wherein the monomers include silane coupling agents containing alkenyl groups and / or acryloyloxy groups; and subjecting the pre-emulsion to emulsion polymerization under heating, inert gas protection, and stirring conditions to obtain silicone-containing organic resin particles.

[0154] 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 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.

[0155] In some embodiments, the method for providing silicon-containing organic resin particles may further include the steps of: drying the product obtained from the emulsion polymerization reaction, and then subjecting it to a crushing process and a wet grinding process to obtain silicon-containing organic resin particles. This yields silicon-containing organic resin particles with a secondary particle morphology.

[0156] In other embodiments, the method for providing silicon-containing organic resin particles 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 silicon-containing organic resin particles. This results in silicon-containing organic resin particles with a secondary particle morphology and better heat resistance.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] In some embodiments, the crushing process can employ air jet mills, vibratory mills, mechanical mills, ultrasonic mills, ball mills, etc.

[0164] In some embodiments, the wet grinding process may include the following steps: mixing crushed material with solvent, grinding media and optional dispersant to obtain a mixed slurry, and then grinding the mixed slurry to obtain silicon-containing organic resin particles.

[0165] Optionally, the solvent may include one or more of water, methanol, and ethanol. More preferably, the solvent may include water.

[0166] Optionally, the dispersant 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.

[0167] Optionally, the polishing media may include one or more of zirconia balls, alumina balls, and silicon nitride balls.

[0168] Optionally, the average particle size of the grinding media can be 0.1 mm to 2 mm.

[0169] Optionally, the grinding speed can be 500rpm-3000rpm.

[0170] 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 silicon-containing organic resin particles.

[0171] In some embodiments, the first temperature can be 55°C-70°C.

[0172] In some embodiments, the first time can be 3h-6h.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] In some embodiments, the monomer may include a vinylsilane coupling agent and / or an acryloyloxysilane coupling agent.

[0177] 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.

[0178] In some embodiments, the crosslinking agent may be a multifunctional crosslinking agent.

[0179] 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.

[0180] In some embodiments, the mass fraction of the crosslinking agent, based on the total mass of monomers and crosslinking agents as 100%, can be 1.5%-18%, for example, it can be 1.5%, 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 range of the above values.

[0181] When the mass fraction of the crosslinking agent is within the above range, silicon-containing organic resin particles with good heat resistance can be obtained.

[0182] Optionally, 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%.

[0183] 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.

[0184] 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.

[0185] 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%.

[0186] 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.

[0187] This disclosure also provides a secondary battery cell. The secondary battery cell includes the separator provided in this disclosure, or a separator prepared by the method of this disclosure. This allows the secondary battery cell to possess both high energy density and high reliability.

[0188] A secondary battery cell also includes a positive electrode, a negative electrode, and an electrolyte, with a separator disposed between the positive and negative electrodes. The positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process.

[0189] 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.

[0190] [Positive electrode plate]

[0191] 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.

[0192] 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, 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.

[0193] 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.

[0194] 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. When 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, and the actual molar O content will also fluctuate.

[0195] 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 / 2Ti 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] [Negative electrode plate]

[0202] 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.

[0203] 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.

[0204] 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.

[0205] 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).

[0206] 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.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] [Electrolytes]

[0212] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0213] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0214] 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).

[0215] 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).

[0216] 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.

[0217] 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.

[0218] Optionally, the additive may include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), and ethylene sulfate (DTD).

[0219] Methods for preparing 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 formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the aforementioned electrolyte. After vacuum sealing, settling, and formation processes, a secondary battery cell is obtained.

[0220] Example

[0221] The following examples describe the contents of this disclosure in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0222] Example 1

[0223] A pre-emulsion was prepared by emulsifying 0.3g sodium persulfate, 0.3g sodium bicarbonate, 1.5g sodium dodecyl sulfate, 30g deionized water, 52g γ-methacryloyloxypropyltriisopropoxysilane, 3g 3-methacryloyloxypropyltriethoxysilane, and 5g divinylbenzene. In a reactor, 210g of deionized water was added, and the temperature was raised to 70°C. Under nitrogen protection and stirring, the pre-emulsion was added dropwise. After reacting for 4 hours, the temperature was raised to 84°C and the reaction was allowed to mature for 1.5 hours to obtain silicon-containing organic resin particles slurry #1.

[0224] The above emulsion, nanocellulose fibers, binder polymethyl methacrylate, and dispersant sodium carboxymethyl cellulose were stirred evenly in deionized water to obtain a porous coating slurry. The length of the nanocellulose fibers ranged from 2 μm to 5 μm, and the diameter ranged from 20 nm to 50 nm. The solid mass ratio of the silicone organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry was 89:1:2:8.

[0225] A commercially available 7μm thick polyethylene microporous film was used as the porous base membrane. The porous coating slurry was coated onto the two surfaces of the porous base membrane using a microgravure method, and then the separator membrane was obtained through drying and slitting processes.

[0226] Example 2

[0227] Except for the following differences, the preparation method of the separator is the same as in Example 1.

[0228] The porous coating slurry contains silicon organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in a solid mass ratio of 88:2:2:8.

[0229] Example 3

[0230] Except for the following differences, the preparation method of the separator is the same as in Example 1.

[0231] The porous coating slurry contains silicon organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in a solid mass ratio of 87:3:2:8.

[0232] Example 4

[0233] Except for the following differences, the preparation method of the separator is the same as in Example 1.

[0234] The porous coating slurry contains silicon organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in a solid mass ratio of 86:4:2:8.

[0235] Example 5

[0236] Except for the following differences, the preparation method of the separator is the same as in Example 1.

[0237] The porous coating slurry contains silicon organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in a solid mass ratio of 85:5:2:8.

[0238] Comparative Example 1

[0239] A pre-emulsion was prepared by emulsifying 0.3g sodium persulfate, 0.3g sodium bicarbonate, 1.5g sodium dodecyl sulfate, 30g deionized water, and 60g γ-methacryloyloxypropyltriisopropoxysilane. In a reactor, 210g of deionized water was added, and the temperature was raised to 70°C. Under nitrogen protection and stirring, the pre-emulsion was added dropwise. After reacting for 4 hours, the temperature was raised to 84°C and the reaction was allowed to mature for 1.5 hours to obtain silicon-containing organic resin particles D1# slurry.

[0240] The above emulsion, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate were stirred and mixed evenly in deionized water to obtain a porous coating slurry. The solid content mass ratio of the porous coating slurry containing silicone organic resin particles D1#, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate was 90:2:8.

[0241] A commercially available 7μm thick polyethylene microporous film was used as the porous base membrane. The porous coating slurry was coated onto the two surfaces of the porous base membrane using a microgravure method, and then the separator membrane was obtained through drying and slitting processes.

[0242] Performance testing

[0243] The heat shrinkage rate test of the release liner can be referenced in GB / T 36363-2018.

[0244] 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.

[0245] Set the temperature of the forced-air drying oven to 140℃. 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.

[0246] 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.

[0247] Table 1

[0248]

[0249] The test results above show that the separator disclosed herein has better heat resistance and can improve the thermal safety performance of secondary battery cells when used in them.

[0250] 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 separating membrane, comprising a porous base membrane and a porous coating located on at least one side of the porous base membrane, characterized in that, The porous coating comprises silicon-containing organic resin particles and fibrous materials, with at least a portion of the silicon-containing organic resin particles located between the fibrous materials.

2. The separator membrane according to claim 1, characterized in that, The silicon-containing organic resin particles have no glass transition temperature below 300°C.

3. The separator according to any one of claims 1-2, characterized in that, The silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, which contain carbon-carbon bonds and silicon-oxygen structures.

4. The separator according to any one of claims 1-3, characterized in that, The silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles. The silicon-containing organic 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.

5. The separator according to any one of claims 1-4, characterized in that, The silicon-containing organic resin particles are silicon-containing organic cross-linked resin particles, and the silicon-containing organic resin particles include cross-linked structural units; Optionally, the crosslinked structural units 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.

6. The separator according to any one of claims 1-5, characterized in that, The silicon-containing organic resin particles satisfy at least one of the following conditions (1) to (4): (1) The silicon-containing organic resin particles have no melting point; (2) The dissolution rate of the silicon-containing organic resin particles 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%. (3) The swelling degree of the silicon-containing organic 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%. (4) The cyclic voltammetry curve of the silicon-containing organic resin particles in the first cycle does not have an oxidation peak in the voltage range of 2.50V to 4.40V.

7. The separator according to any one of claims 1-6, characterized in that, The volume distribution particle size Dv50 of the silicon-containing organic resin particles is 80nm-800nm; and / or, The true density of the silicon-containing organic resin particles is 1.1 g / cm³. 3 -1.5g / cm 3 .

8. The separator according to any one of claims 1-7, characterized in that, The diameter of the fibrous material ranges from 10 nm to 200 nm; and / or, The length of the fibrous material ranges from 0.15 μm to 30 μm.

9. The separator according to any one of claims 1-8, characterized in that, The fibrous material includes one or more of the following: glyco-based fibers, protein-based fibers, polymer fibers, and inorganic fibers; Optionally, the fibrous material includes one or more of the following: alginate and its derivative fibers, nanocellulose and its derivative fibers, chitosan and its derivative fibers, chitin and its derivative fibers, plant cellulose, silk protein fibers, spider silk protein fibers, corn protein fibers, soybean protein fibers, keratin fibers, wool fibers, cashmere fibers, aramid fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyethylene fibers, ultra-high molecular weight polyethylene fibers, polypropylene fibers, polytetrafluoroethylene fibers, polyvinylidene fluoride fibers, polyurethane fibers, acetate fibers, polycaprolactone fibers, polylactic acid fibers, polyethersulfone fibers, acrylic fibers, acrylic polymer fibers, polymethyl methacrylate fibers, poly(2-hydroxyethyl methacrylate) fibers, polyethylene phthalate fibers, polyethylene terephthalate fibers, p-phenylenediamine terephthalate fibers, glass fibers, asbestos fibers, and silica fibers.

10. The separator according to any one of claims 1-9, characterized in that, The fibrous material has polar groups; Optionally, the polar group includes one or more of the following: hydroxyl, carboxyl, ester, amide, cyano, amino, aldehyde, sulfonic acid, boric acid, and phosphate.

11. The separator according to any one of claims 1-10, characterized in that, Based on the total mass of the porous coating, the mass content of silicon-containing organic resin particles in the porous coating is greater than or equal to 55%; and / or, The fibrous material content in the porous coating is 0.3%-30% based on the total mass of the porous coating.

12. The separator according to any one of claims 1-11, characterized in that, The porous coating further includes an adhesive; and / or, The thickness of the porous coating is 0.5μm-5μm.

13. A method for preparing the separator membrane according to any one of claims 1-12, comprising the following steps: providing a porous base membrane; providing a slurry comprising silicone organic resin particles, fibrous material, and binder; coating the slurry onto at least one side of the porous base membrane, and drying to obtain the separator membrane.

14. The method according to claim 13, characterized in that, A method for providing silicon-containing organic resin particles includes the following steps: providing a pre-emulsion comprising monomers, crosslinking agents, emulsifiers, initiators, and water, wherein the monomers include silane coupling agents containing alkenyl and / or acryloyloxy groups; and subjecting the pre-emulsion to emulsion polymerization under heating, inert gas protection, and stirring conditions to obtain silicon-containing organic resin particles.

15. The method according to claim 14, characterized in that, The method further includes the steps of drying the product obtained from the emulsion polymerization reaction, and then crushing and wet grinding to obtain silicon-containing organic resin particles.

16. The method according to claim 14, characterized in that, The method further includes the steps of: drying the product obtained from the emulsion polymerization reaction, baking it under an inert gas atmosphere, and then crushing and wet grinding it to obtain silicon-containing organic resin particles.

17. The method according to any one of claims 14-16, characterized in that, The monomers 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, and vinyltri(β-methyl)silane. One or more of the following: (1-methylvinyl)oxysilane, vinyltris[(1-methylvinyl)oxy]silane, vinyltritert-butylperoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, methacryloyloxypropyldimethylmethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, 3-methacryloyloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyldimethylethoxysilane, methylvinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylvinyldimethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane; and / or, The crosslinking agent comprises 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-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; and / or, With the total mass of the monomer and the crosslinking agent being 100%, the mass fraction of the crosslinking agent is 1.5%-18%.

18. The method according to any one of claims 14-17, characterized in that, The emulsion polymerization reaction includes the following steps: under a first temperature, inert gas protection and stirring conditions, the pre-emulsion is dropwise added to a reactor containing water, and after a first reaction time, the temperature is raised to a second temperature to mature the reaction for a second time, thereby obtaining silicon-containing organic resin particles.

19. The method according to claim 18, characterized in that, The first temperature is 55℃-70℃; and / or, The first time period is 3h-6h; and / or, The second temperature is 72℃-92℃; and / or, The second time period is 1 hour to 5 hours; and / or, The inert gas includes one or more of nitrogen, argon, and helium.

20. A secondary battery cell, characterized in that, It includes a positive electrode, a negative electrode, and a separator as described in any one of claims 1-12, wherein the separator is disposed between the positive electrode and the negative electrode.

21. A battery device, characterized in that, It includes multiple secondary battery cells as described in claim 20.

22. An electrical appliance, characterized in that, Includes the secondary battery cell of claim 20 or the battery device of claim 21.

Images