Separator and preparation method therefor, secondary battery cell, battery apparatus, and electric apparatus

Abstract

A separator and a preparation method therefor, a secondary battery cell, a battery apparatus, and an electric apparatus. The separator comprises a porous base film and a porous coating located on at least one side of the porous base film; the porous coating comprises silicon-containing organic resin particles and fibrous material; and at least some of the silicon-containing organic resin particles are located within the fibrous material. The separator is used in the secondary battery cell, such that the secondary battery cell has both high gravimetric energy density and high reliability.

Description

Separator and method for manufacturing the same, secondary battery cell, battery device, and power using device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese Patent Application No. 202411388490.7, filed on September 30, 2024, entitled “Separator and method for manufacturing the same, secondary battery cell, battery device, and power using device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a separator and method for manufacturing the same, secondary battery cell, battery device, and power using device. BACKGROUND

[0004] With the increasingly wide range of applications of secondary battery cells, people’s demand for the use of secondary battery cells is also increasing, such as the increasingly high requirements for the energy density and reliability of secondary battery cells. Therefore, how to make the secondary battery cell have higher energy density under the premise of high reliability is a technical problem to be solved at present. SUMMARY

[0005] The present disclosure provides a separator and method for manufacturing the same, secondary battery cell, battery device, and power using device, which is used in a secondary battery cell and can make the secondary battery cell have high mass energy density and high reliability.

[0006] In a first aspect, the present disclosure provides a separator, which comprises a porous base film and a porous coating layer located on at least one side of the porous base film, the porous coating layer comprising silicon-containing organic resin particles and fibrous material, and at least a part of the silicon-containing organic resin particles being located between the fibrous material.

[0007] The density of the silicon-containing organic resin particles and the fibrous material is small, so that the secondary battery cell using the same can have higher mass energy density. The porous coating layer of the separator of the present disclosure comprises a mixture of silicon-containing organic resin particles and fibrous material, and after the introduction of the fibrous material, the silicon-containing organic resin particles can be connected in series and dispersed, so that the structural property and heat resistance of the whole porous coating layer can be improved, thereby reducing the thermal shrinkage of the whole separator and improving the reliability of the secondary battery cell. Therefore, the separator of the present disclosure can make the secondary battery cell have high mass energy density and high reliability.

[0008] In some embodiments, the silicon-containing organic resin particles have no glass transition temperature below 300°C. The silicon-containing organic resin particles having no glass transition temperature below 300°C indicate that the particles have good heat resistance and thermal stability, and thus can better resist thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0009] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles contain carbon-carbon bonds and siloxane structures.

[0010] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles are network structures formed with carbon-carbon bonds as the main chain, and side chains containing siloxane structures and benzene ring structures.

[0011] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles include crosslinking structure units.

[0012] Optionally, the crosslinking structure units include one or more of divinylbenzene structure units, diethylene glycol divinyl ether structure units, triethylene glycol divinyl ether structure units, diallyl maleate structure units, ethylene glycol dimethacrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethyladipoyl bis[2-ethylaziridine] structure units, 1,1-sebacoyl bis[2-methylaziridine] structure units, 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tris(3-aziridinyl) propionate structure units.

[0013] In some embodiments, the silicon-containing organic resin particles have no melting point. The silicon-containing organic resin particles having no melting point indicate that the particles have good heat resistance and thermal stability, and thus can better resist thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0014] In some embodiments, the silicon-containing organic resin particles have a dissolution rate of 3% or less when 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. The silicon-containing organic resin particles have a low dissolution rate in the organic solvent, high structural stability during long-term use of the secondary battery cell, and high chemical stability in the electrolyte, thereby allowing the secondary battery cell to have a longer cycle stability.

[0015] In some embodiments, the silicon-containing organic resin particles have a swelling degree of 3% or less when 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. The silicon-containing organic resin particles have a low swelling degree in the organic solvent, high structural stability during long-term use of the secondary battery cell, and thereby improve the problem of a decrease in the air permeability of the separator during use.

[0016] In some embodiments, the silicon-containing organic resin particles have no oxidation peak in the cyclic voltammetry curve of the first cycle in a voltage range of 2.50V to 4.40V. The silicon-containing organic resin particles having no oxidation peak in the cyclic voltammetry curve of the first cycle in a voltage range of 2.50V to 4.40V indicate that the silicon-containing organic resin particles are stable in a voltage range of 2.50V to 4.40V. Thus, the silicon-containing organic resin particles of the present disclosure have good electrochemical stability, can be applied to high-voltage secondary battery cells, improve the operating voltage and energy density of the secondary battery cells, and allow the secondary battery cells to have good capacity release characteristics at high voltage.

[0017] In some embodiments, the silicon-containing organic resin particles have a volume distribution particle size Dv50 of 80nm to 800nm.

[0018] The silicon-containing organic resin particles have a volume distribution particle size Dv50 in the above range, which is advantageous for the porous coating of the separator to have good heat resistance and air permeability.

[0019] In some embodiments, the silicon-containing organic resin particles have a true density of 1.1g / cm 3 -1.5g / cm 3 .

[0020] In some embodiments, the fibrous material has a diameter in a range of 10nm to 200nm.

[0021] In some embodiments, the fibrous material has a length in a range of 0.15μm to 30μm.

[0022] The length of the fibrous material is within the above range, which can better connect the silicon-containing organic resin particles in series, improve the structural properties and heat resistance of the porous coating as a whole, reduce the thermal shrinkage of the separator as a whole, and improve the air permeability of the separator.

[0023] In some embodiments, the fibrous material comprises one or more of sugar-based fibers, protein-based fibers, polymer fibers, and inorganic fibers.

[0024] In some embodiments, the fibrous material comprises one or more of alginate fibers and derivatives thereof, nanocellulose fibers and derivatives thereof, chitosan fibers and derivatives thereof, chitin fibers and derivatives thereof, plant cellulose, silk fibroin fibers, spider silk fibers, corn protein fibers, soy 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, polyether sulfone fibers, acrylic fibers, acrylic polymer fibers, polymethyl methacrylate fibers, poly-2-hydroxyethyl methacrylate fibers, polyethylene terephthalate fibers, polyethylene terephthalate fibers, polyphenylene terephthalamide fibers, glass fibers, asbestos fibers, and silica fibers.

[0025] In some embodiments, the fibrous material has a polar group.

[0026] Optionally, the polar group comprises one or more of a hydroxyl group, a carboxyl group, an ester group, an amide group, a cyano group, an amine group, an aldehyde group, a sulfonic acid group, a boronic acid group, and a phosphoric acid group.

[0027] The fibrous material has a polar group, which can form stronger interactions, such as hydrogen bonds or ionic bonds, with the binder in the porous coating, so that the adhesion between the porous coating and the porous base film is stronger, thereby improving the structural properties of the separator as a whole and improving the heat resistance of the separator.

[0028] 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.

[0029] In some embodiments, the mass content of the fibrous material in the porous coating is 0.3%-30% based on the total mass of the porous coating. The mass content of the fibrous material within the above range can make the separator have good heat resistance and air permeability, thereby making the secondary battery cell have high reliability and good cycle performance.

[0030] In some embodiments, the porous coating further comprises a binder.

[0031] In some embodiments, the thickness of the porous coating layer is 0.5-5 μm.

[0032] In a second aspect, the present disclosure provides a method for preparing the separator film of the first aspect, comprising the steps of: providing a porous base film; providing a slurry comprising silicon-containing organic resin particles, fibrous material, and a binder; coating the slurry on at least one side of the porous base film, and drying to obtain the separator film.

[0033] In some embodiments, the method for providing the silicon-containing organic resin particles comprises the steps of: providing a pre-emulsion comprising monomers, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomers comprise a silane coupling agent containing alkenyl and / or acryloyloxy groups; and subjecting the pre-emulsion to emulsion polymerization under heating, inert gas protection, and stirring to obtain the silicon-containing organic resin particles.

[0034] In some embodiments, the method further comprises the step of: drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a crushing process and a wet grinding process to obtain the silicon-containing organic resin particles.

[0035] In some embodiments, the method further comprises the step of: drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a baking process in an inert gas atmosphere, and then subjecting the baked product to a crushing process and a wet grinding process to obtain the silicon-containing organic resin particles.

[0036] In some embodiments, the monomer comprises one or more of gamma-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, gamma-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltris(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(β-methoxyethoxy)silane, ethylene tris[(l-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyldimethylethoxysilane, methylethyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylethyldimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0037] In some embodiments, the crosslinking agent comprises one or more of divinylbenzene, diethylene glycol divinyl ether, triethylene glycol divinyl ether, maleic acid diallyl ester, 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-trimethylhexanedioic acid bis[2-ethylaziridine], 1,1-nonanedioic acid bis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-l-aziridinylpropionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate.

[0038] 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%.

[0039] In some embodiments, the emulsion polymerization reaction comprises the step of: dropping the pre-emulsion into a reactor containing water under the conditions of a first temperature, inert gas protection and stirring, and after a first reaction time, warming to a second temperature for a second reaction time to obtain silicon-containing organic resin particles.

[0040] In some embodiments, the first temperature is 55-70℃.

[0041] In some embodiments, the first time is 3-6h.

[0042] In some embodiments, the second temperature is 72-92℃.

[0043] In some embodiments, the second time is 1-5h.

[0044] In some embodiments, the inert gas comprises one or more of nitrogen, argon, and helium.

[0045] In a third aspect, the present disclosure provides a secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator of the first aspect of the present disclosure, the separator being disposed between the positive electrode sheet and the negative electrode sheet.

[0046] In a fourth aspect, the present disclosure provides a battery device comprising a plurality of the secondary battery cell of the third aspect of the present disclosure.

[0047] In a fifth aspect, the present disclosure provides an electric device comprising the secondary battery cell of the third aspect of the present disclosure or the battery device of the fourth aspect of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments of the present disclosure will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings.

[0049] FIG. 1 shows a schematic diagram of a secondary battery cell according to some embodiments of the present disclosure.

[0050] FIG. 2 shows a schematic diagram of an electric device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0051] Hereinafter, specific embodiments of the separator of the present disclosure and the method for manufacturing the same, the secondary battery cell, the battery device, and the electric device will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters known to those skilled in the art, redundant descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0052] The ranges disclosed herein are defined by their lower and upper endpoints, given that a range is defined by selecting a lower endpoint and an upper endpoint, the selected lower and upper endpoints define the boundaries of the particular range. Ranges defined by endpoints can be either inclusive or exclusive of the endpoints, and can be arbitrarily combined, i.e., any lower endpoint can be combined with any upper endpoint to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Also, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all of the individual real combinations that fall between "a" and "b", where "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand way of describing these numerical combinations. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0053] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0054] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0055] Unless otherwise specified, all steps of the present disclosure can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0056] Unless otherwise specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects, and are not used to describe a particular order or primary and secondary relationship.

[0057] In the present disclosure, the terms "a plurality of", "a plurality of" refer to two or more.

[0058] In the description of the embodiments of the present disclosure, if there is no special indication, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "below", "under" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0059] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25°C.

[0060] The secondary battery cell mentioned in the embodiments of the present disclosure can realize the function of charging and discharging independently, and can continue to be used by activating the active material through charging after discharging. The secondary battery cell can be in the shape of a cylinder, a cuboid or other shapes, which are not limited in the embodiments of the present disclosure. As shown in FIG. 1, the secondary battery cell 5 is a cuboid structure as an example.

[0061] The secondary battery cell provided by the embodiments of the present disclosure can include but is not limited to lithium battery cells, sodium battery cells, such as lithium ion battery cells, sodium ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0062] The secondary battery cell provided by the embodiments of the present disclosure includes an electrode assembly. The electrode assembly can be a winding structure or a stacking structure, which is not limited in the embodiments of the present disclosure. The secondary battery cell further includes an outer package, which can be used to package the electrode assembly. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-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).

[0063] The battery apparatus mentioned in the embodiments of the present disclosure can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of secondary battery cells connected in series, in parallel or in a mixed manner through a busbar component.

[0064] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of secondary battery cells.

[0065] As an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of secondary battery cells into one independent module. As an example, the battery module can be formed by bundling a plurality of secondary battery cells with a cable tie.

[0066] In some embodiments, the battery device can be a battery pack, which includes a case and one or more battery cell assemblies accommodated in the case.

[0067] As an example, the battery cell assembly can be a battery module, which can be accommodated in the case by fixing the battery module in the case.

[0068] As an example, the battery cell assembly can also be accommodated in the case by directly fixing a plurality of secondary battery cells in the case.

[0069] As an example, the case can include a first case and a second case. The first case and the second case are fastened so that an enclosed space is formed inside the case to accommodate the battery cell assembly. Here, the enclosed means covered or closed, which can be sealed or unsealed. The first case can be a top cover or a bottom plate.

[0070] As an example, the case can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are connected to the frame, respectively, so that an enclosed space is formed inside the case to accommodate the battery cell assembly.

[0071] In some embodiments, the case can be part of a chassis structure of a vehicle. For example, part of the case can be at least part of a floor of the vehicle, or part of the case can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0072] The technical solutions described in the embodiments of the present disclosure are applicable to various electric devices using secondary battery cells and battery devices, such as, but not limited to, mobile devices (such as mobile phones, tablet computers, notebook computers, etc.), electric vehicles (such as 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. The secondary battery cells and the battery devices are used to store or provide electric energy.

[0073] FIG. 2 is a schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0074] In the context of the present disclosure, the silicon-containing organic resin particles mainly play a role in improving heat resistance in the porous coating of the separator film, and almost have no adhesion.

[0075] The separator film is an important component for supporting the secondary battery cell to complete the charge-discharge electrochemical process. The commonly used separator film is mostly polyolefin film. However, the heat resistance of the polyolefin film is poor, and the polyolefin film is easy to soften or melt at high temperature, which may cause short circuit of the secondary battery cell. In order to improve the heat resistance of the separator film, a porous coating layer is usually coated on the separator film to improve the heat resistance of the separator film. Inorganic particles such as boehmite and aluminum oxide are currently commonly used heat-resistant fillers. However, the density of such heat-resistant fillers is relatively large, and the mass is large under the same packing volume, which affects the energy density of the secondary battery cell.

[0076] Therefore, the separator film of the present disclosure can make the secondary battery cell have high mass energy density and high reliability.

[0077] The separator film of the present disclosure comprises a porous base film and a porous coating layer located on at least one side of the porous base film. The porous coating layer comprises silicon-containing organic resin particles and fibrous material, and at least a part of the silicon-containing organic resin particles is located between the fibrous material.

[0078] The porous base film and the porous coating layer both have a pore structure, so that the separator film has good air permeability and facilitates the passage of ions.

[0079] The density of the silicon-containing organic resin particles and the fibrous material is small, so that the secondary battery cell using the same has higher mass energy density.

[0080] The heat resistance of the silicon-containing organic resin particles alone is not excellent; the fibrous material has the characteristics of high strength, high heat resistance and low thermal shrinkage, but has a small diameter. When used alone and used in the separator film, there is a problem of reducing the air permeability of the separator film. The porous coating layer of the separator film of the present disclosure simultaneously comprises a mixture of silicon-containing organic resin particles and fibrous material. After the introduction of the fibrous material, the silicon-containing organic resin particles can be connected in series and dispersed, so that the overall structure and heat resistance of the porous coating layer can be improved, thereby reducing the overall thermal shrinkage of the separator film and improving the reliability of the secondary battery cell.

[0081] Therefore, the separator film of the present disclosure can make the secondary battery cell have high mass energy density and high reliability.

[0082] The silicon-containing organic resin particles of the present disclosure are difficult to dissolve in water and organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), and chloroform at 25°C, i.e. insoluble in the mobile phase for gel permeation chromatography test, and the molecular weight of the silicon-containing organic resin particles cannot be tested by gel permeation chromatography.

[0083] In some embodiments, the true density of the silicon-containing organic resin particles can be 1.1 g / cm 3-1.5g / cm 3 .

[0084] Currently, the true density of inorganic particles such as boehmite and alumina is usually 2.5g / cm 3 -3.5g / cm 3 The true density of the silicon-containing organic resin particles of the present disclosure is small, thereby enabling a secondary battery cell employing the separator film of the present disclosure to have a higher mass energy density.

[0085] In some embodiments, the silicon-containing organic resin particles have no glass transition temperature below 300°C.

[0086] The silicon-containing organic resin particles have no glass transition temperature below 300°C, indicating that they have good heat resistance and thermal stability, thereby enabling them to better resist thermal shrinkage of the porous base film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0087] The glass transition temperature T g may be tested according to the following method: take an appropriate amount of sample (e.g., 5mg-15mg) and place it in a differential scanning calorimeter (DSC) crucible, shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: increase the temperature from 25°C to 200°C at a rate of 10°C / min, hold for 5min to eliminate thermal history, then decrease the temperature from 200°C to -40°C at a rate of 10°C / min, and then increase the temperature to 300°C at a rate of 10°C / min. Determine whether the silicon-containing organic resin particles have a glass transition temperature T g .

[0088] The glass transition temperature T g refers to the transition temperature from the glass state to the high-elasticity state, which shows a step change on the DSC curve.

[0089] The silicon-containing organic resin particles have no glass transition temperature T g refers to the fact that the DSC curve of the silicon-containing organic resin particles does not show a step change in the range below 300°C.

[0090] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles contain carbon-carbon bonds and siloxane structures.

[0091] Alternatively, the silicon-containing organic resin particles are network structures formed with carbon-carbon bonds as the main chain, and the side chains contain siloxane structures.

[0092] Alternatively, the silicon-containing organic resin particles are network structures formed with carbon-carbon bonds as the main chain, and the side chains contain siloxane structures and benzene ring structures.

[0093] In some embodiments, the silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles include crosslinking structural units.

[0094] The crosslinking structural unit of the silicon-containing organic crosslinked resin refers to a non-silicon-containing structural unit for connecting the silicon-containing structural units.

[0095] Optionally, the crosslinking structural unit can include one or more of a divinylbenzene structural unit, a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a maleic acid diallyl ester 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, a tripropylene glycol diacrylate structural unit, a 2,2,4-trimethyladipoyl bis[2-ethylaziridine] structural unit, a 1,1-sebacoyl bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structural unit, a trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structural unit, a trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structural unit, a pentaerythritol tris(3-aziridinyl) propionate structural unit.

[0096] In some embodiments, the silicon-containing organic resin particles have no melting point.

[0097] The silicon-containing organic resin particles of the present disclosure have no melting point, indicating that they have good heat resistance and thermal stability, and thus can better resist thermal shrinkage of the porous base film, improve the heat resistance of the isolation film, and improve the reliability of the secondary battery cell.

[0098] The melting point can be tested according to the following method: take an appropriate amount of sample (e.g., 5 mg-15 mg) and place it in a differential scanning calorimeter (DSC) crucible, shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; program settings: increase the temperature from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, then decrease the temperature from 200°C to -40°C at a rate of 10°C / min, and then increase the temperature to 300°C at a rate of 10°C / min. Determine whether the silicon-containing organic resin particles have a melting point below 300°C by the DSC curve. The silicon-containing organic resin particles have no melting point, meaning that the DSC curve of the silicon-containing organic resin particles has no melting peak.

[0099] In some embodiments, the silicon-containing organic resin particles have a dissolution rate of less than or equal to 3% in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days.

[0100] The silicon-containing organic resin particles have a low dissolution rate in an organic solvent, high structural stability during long-term use of the secondary battery cell, and high chemical stability in the electrolyte, thereby providing the secondary battery cell with longer cycle stability.

[0101] The dissolution rate of the silicon-containing organic resin particles can be tested by the following method: taking an appropriate amount of sample (e.g., about 1 g) and weighing it as m1, placing it in a semi-permeable membrane sample bag, sealing the bag, recording the total mass of the sample bag as m2, and immersing the sample bag in an appropriate amount of solvent (e.g., about 50 g) at 60°C for 7 days. Then, the sample bag is taken out, drained, and dried, and the total mass of the sample bag is weighed again as m3. The dissolution rate is (m2-m3) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0102] In some embodiments, the silicon-containing organic resin particles have a swelling degree of less than or equal to 3% in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days.

[0103] The silicon-containing organic resin particles have a low swelling degree in an organic solvent, high structural stability during long-term use of the secondary battery cell, and thereby improve the problem of decreased air permeability of the separator during use.

[0104] The swelling degree of the silicon-containing organic resin particles can be tested by the following method: taking an appropriate amount of sample (e.g., about 1 g) and weighing it as m1, placing it in a semi-permeable membrane sample bag, sealing the bag, and immersing the sample bag in an appropriate amount of solvent (e.g., about 50 g) at 60°C for 7 days. Then, the sample bag is taken out, and the sample is taken out of the sample bag, excess solvent is wiped off, and the mass of the sample is weighed again as m2. The swelling degree is (m2-m1) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0105] In some embodiments, the silicon-containing organic resin particles have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.50V to 4.40V.

[0106] The cyclic voltammogram of the silicon-containing organic resin particles in the first cycle has no oxidation peak in the voltage range of 2.50V to 4.40V, which indicates that the silicon-containing organic resin particles are stable in the voltage range of 2.50V to 4.40V. Therefore, the silicon-containing organic resin particles of the present disclosure have good electrochemical stability, can be applied in high-voltage secondary battery cells, improve the working voltage and energy density of the secondary battery cells, and also enable the secondary battery cells to have good capacity performance characteristics at high voltage.

[0107] The oxidation peak potential of the cyclic voltammogram of the silicon-containing organic resin particles can be tested as follows: the silicon-containing organic resin particles, the binder polymethyl methacrylate, and the conductive agent conductive carbon black are dissolved in water in a solid content mass ratio of 64:7:29 to form a slurry, the slurry is coated on an aluminum foil as a positive electrode, a lithium foil is used as a negative electrode, and a button cell is assembled; the button cell is subjected to cyclic voltammetry (CV) test, the scanning rate is 0.10mV / s, the voltage range is 2.50V-5.00V, and the cycle is 3 cycles, and the voltage corresponding to the peak point of the first cycle cyclic voltammogram is taken as the oxidation peak potential. The electrolyte salt of the electrolyte used for testing is LiPF6, and the concentration is 1mol / L. The solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0108] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin particles can be 80nm-800nm.

[0109] The volume distribution particle size Dv50 of the silicon-containing organic resin particles is in the above range, which is beneficial to the porous coating of the separator membrane to have good heat resistance and air permeability.

[0110] Dv50 represents the particle size corresponding to the cumulative volume distribution percentage of 50%, which can be tested by a laser particle size analyzer according to GB / T 19077-2016. During testing, a clean small beaker is taken, 1g of the sample to be tested is added, 20ml of deionized water is added, and ultrasonic treatment is performed at 53KHz / 120W for 5min to ensure complete dispersion of the sample; the laser particle size analyzer is turned on, the light path system is cleaned, and the background is automatically tested; the ultrasonically treated sample solution is stirred to make it uniformly dispersed, and then it is placed in the sample cell as required, and the particle size is measured. The testing instrument can be a MasterSizer 3000 laser particle size analyzer.

[0111] In some embodiments, the diameter of the fibrous material can range from 10nm to 200nm.

[0112] Optionally, the fibrous material can have a diameter in the range of 10 nm to 160 nm, 12 nm to 160 nm, 14 nm to 160 nm, 16 nm to 160 nm, 18 nm to 160 nm, 20 nm to 160 nm, 10 nm to 120 nm, 12 nm to 120 nm, 14 nm to 120 nm, 16 nm to 120 nm, 18 nm to 120 nm, 20 nm to 120 nm, 10 nm to 100 nm, 12 nm to 100 nm, 14 nm to 100 nm, 16 nm to 100 nm, 18 nm to 100 nm, 20 nm to 100 nm, 10 nm to 80 nm, 12 nm to 80 nm, 14 nm to 80 nm, 16 nm to 80 nm, 18 nm to 80 nm, 20 nm to 80 nm, 14 nm to 50 nm, 16 nm to 50 nm, 18 nm to 50 nm, 20 nm to 50 nm.

[0113] In some embodiments, the fibrous material can have a length in the range of 0.15 pm to 30 pm.

[0114] Optionally, the fibrous material can have a length in the range of 0.3 pm to 20 pm, 0.4 pm to 20 pm, 0.5 pm to 20 pm, 0.6 pm to 20 pm, 0.8 pm to 20 pm, 0.3 pm to 15 pm, 0.4 pm to 15 pm, 0.5 pm to 15 pm, 0.6 pm to 15 pm, 0.8 pm to 15 pm, 0.3 pm to 10 pm, 0.4 pm to 10 pm, 0.5 pm to 10 pm, 0.6 pm to 10 pm, 0.8 pm to 10 pm, 0.3 pm to 8 pm, 0.4 pm to 8 pm, 0.5 pm to 8 pm, 0.6 pm to 8 pm, 0.8 pm to 8 pm, 0.3 pm to 5 pm, 0.4 pm to 5 pm, 0.5 pm to 5 pm, 0.6 pm to 5 pm, 0.8 pm to 5 pm, 0.3 pm to 4 pm, 0.4 pm to 4 pm, 0.5 pm to 4 pm, 0.6 pm to 4 pm, 0.8 pm to 4 pm.

[0115] The fibrous material can have a length in the above range, which can better connect the silicon-containing organic resin particles, improve the structure and heat resistance of the porous coating as a whole, reduce the thermal shrinkage of the isolation film as a whole, and improve the air permeability of the isolation film.

[0116] In some embodiments, the fibrous material can include one or more of sugar-based fibers, protein-based fibers, polymeric fibers, and inorganic fibers.

[0117] In some embodiments, the fibrous material can include one or more of alginic acid and its derivative fibers, nanocellulose and its derivative fibers, chitosan and its derivative fibers, chitin and its derivative fibers, plant cellulose, silk fibroin fibers, spider silk fibroin fibers, corn protein fibers, soy 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 terephthalate fibers, polyethylene terephthalate fibers, para-phenylenediamine terephthalic acid fibers, glass fibers, asbestos fibers, silica fibers.

[0118] Optionally, the alginic acid and its derivative fibers can include one or more of alginic acid fibers, alginate fibers, and other chemically modified alginic acid derivative fibers.

[0119] Optionally, the nanocellulose and its derivative fibers can 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.

[0120] Optionally, the chitosan and its derivative fibers can include one or more of 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.

[0121] Optionally, the chitin and its derivative fibers can 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.

[0122] Plant cellulose refers to cellulose made from plants that are rich in cellulose. Optionally, the plant cellulose can include one or more of bamboo cellulose, cotton cellulose, lignocellulose, herbaceous plant cellulose, sugar cane bagasse cellulose, flax cellulose.

[0123] In some embodiments, the fibrous material can have polar groups.

[0124] Optionally, the polar group can include one or more of a hydroxyl group, a carboxyl group, an ester group, an amide group, a cyano group, an amine group, an aldehyde group, a sulfonic acid group, a boronic acid group, a phosphoric acid group.

[0125] The fibrous material has a polar group, so that it can have stronger interaction with the binder in the porous coating, such as forming hydrogen bond or ionic bond, etc., so that the adhesion between the porous coating and the porous base film is stronger, thereby improving the overall structural integrity of the separator film and improving the heat resistance of the separator film.

[0126] In some embodiments, the mass content of the silicon-containing organic resin particles in the porous coating can be greater than or equal to 55% based on the total mass of the porous coating. Optionally, the mass content of the silicon-containing organic resin particles in the porous coating can 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%, greater than or equal to 80%.

[0127] In some embodiments, the mass content of the fibrous material in the porous coating can be 0.3%-30%, such as 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 a range consisting of any of the above values, based on the total mass of the porous coating.

[0128] 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%, 0.5%-4%.

[0129] The mass content of the fibrous material in the above range can make the separator film have good heat resistance and air permeability, so that the secondary battery cell has high reliability and good cycle performance.

[0130] In some embodiments, the porous coating includes a binder, which can include but is not limited to one or more of a polyacrylate-based binder, a nitrile rubber-based binder, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0131] In some embodiments, the mass content of the binder in the porous coating can be 0.5%-10%, for example, 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 a range consisting of any of the aforementioned values, based on the total mass of the porous coating. Alternatively, the mass content of the binder in the porous coating can be 1%-8%.

[0132] In some embodiments, the porous coating can further include a dispersant, for example, can include but is not limited to one or more of alkylphenol polyoxyethylene ether and the like, polyacrylic dispersant, cellulose dispersant. As an example, the dispersant can include but is not limited to one or more of sodium carboxymethyl cellulose, sodium polyacrylate, ammonium polyacrylate.

[0133] In some embodiments, the separator film can further include polymer binder particles.

[0134] The "polymer binder particles" in the porous coating of the separator film play a role in improving the adhesion of the separator film to the pole piece, and have substantially no high-temperature resistance.

[0135] In some embodiments, the polymer binder particles can be embedded in the silicon-containing organic resin particles and the fibrous material and form protrusions on the surface of the porous coating.

[0136] In other embodiments, the porous coating of the separator film includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on the porous base film, the bonding layer is disposed on at least a portion of the surface of the heat-resistant layer away from the porous base film, the silicon-containing organic resin particles are disposed in the heat-resistant layer, and the polymer binder particles are disposed in the bonding layer.

[0137] In yet other embodiments, the porous coating of the separator film includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a portion of the surface of the other side of the porous base film, the silicon-containing organic resin particles are disposed in the heat-resistant layer, and the polymer binder particles are disposed in the bonding layer.

[0138] In some embodiments, the average particle size of the polymer binder particles can be 6 μm-18 μm.

[0139] In some embodiments, the polymer binder particles can include vinylidene fluoride-based polymer particles, for example, polyvinylidene fluoride (PVDF) particles and / or copolymer particles of a vinylidene fluoride monomer and a comonomer.

[0140] The comonomer can include at least one of an olefin monomer, a fluorine-containing olefin monomer, a chlorine-containing olefin monomer, an acrylate monomer, an acrylic monomer, and a fluorine ether monomer.

[0141] Optionally, the comonomer can include at least one of 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-dioxolane), and perfluoro(2,2-dimethyl-1,3-dioxolane).

[0142] In some embodiments, the thickness of the porous coating layer can be 0.5 μm-5 μm. The thickness of the porous coating layer refers to the thickness of the porous coating layer on one side of the porous base film. Optionally, the thickness of the porous coating layer 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, 0.8 μm-2 μm.

[0143] In some embodiments, the porous base film can include a film or nonwoven web selected from any one or at least two of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyether sulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, and polyvinyl naphthalene.

[0144] The porous base film can be a single-layer film or a multi-layer composite film. When the porous base film is a multi-layer composite film, the materials of the layers can be the same or different.

[0145] In some embodiments, the thickness of the porous base film can be 4 μm-12 μm, optionally 4 μm-9 μm.

[0146] In some embodiments, the porosity of the porous base film can be 25%-60%, optionally 28%-50%.

[0147] In some embodiments, the thickness of the separation film can be 5 μm-14 μm, optionally 5 μm-12 μm, 6 μm-12 μm. This is conducive to improving the energy density of the secondary battery cell.

[0148] It should be noted that the above-mentioned porous coating parameters of the separation film are the porous coating parameters on one side of the porous base film. When the porous coating is arranged on both sides of the porous base film, the porous coating parameters of any one side thereof meeting the present disclosure are considered to fall within the protection scope of the present disclosure.

[0149] The present disclosure also provides a method for preparing the separation membrane.

[0150] The method for preparing the separation membrane comprises the following steps: providing a porous base film; providing a slurry comprising silicon-containing organic resin particles, fibrous material, and a binder; and coating the slurry on at least one side of the porous base film to obtain the separation membrane after drying.

[0151] In some embodiments, the slurry can further comprise polymer binder particles, and after drying of the slurry, the polymer binder particles are embedded in the silicon-containing organic resin particles and the fibrous material and form protrusions on the surface of the porous coating.

[0152] In some embodiments, the method for preparing the separation membrane can comprise the following steps: coating a heat-resistant layer slurry comprising silicon-containing organic resin particles and a binder on at least one side of the porous base film to form a heat-resistant layer after drying; and coating a bonding layer slurry comprising polymer binder particles and a binder on at least a part of the surface of the heat-resistant layer to obtain the separation membrane after drying.

[0153] In some embodiments, the method for preparing the separation membrane can comprise the following steps: coating a heat-resistant slurry comprising silicon-containing organic resin particles and a binder on one side of the porous base film, and coating a bonding layer slurry comprising polymer binder particles and a binder on at least a part of the surface of the other side of the porous base film to obtain the separation membrane after drying.

[0154] In some embodiments, the solvent of the slurry can be water, such as deionized water.

[0155] In some embodiments, the slurry can further comprise other components, such as a dispersant and / or a wetting agent, etc.

[0156] In some embodiments, the method for providing the silicon-containing organic resin particles can comprise the following steps: providing a pre-emulsion comprising monomers, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomers comprise a silane coupling agent containing an alkenyl group and / or an acryloyloxy group; and performing emulsion polymerization of the pre-emulsion under heating, inert gas protection, and stirring to obtain the silicon-containing organic resin particles.

[0157] The monomers comprise a silane coupling agent containing an alkenyl group and / or an acryloyloxy group, so that free radicals are generated between the monomers to initiate crosslinking reactions, and the monomers also undergo crosslinking reactions with the crosslinking agent. Therefore, the silicon-containing organic resin particles with a three-dimensional network molecular structure can be formed using the monomers and the crosslinking agent of the present disclosure, which are not easy to soften or deform at high temperatures and have high heat resistance.

[0158] In some embodiments, the method for providing the silicon-containing organic resin particles can further comprise a step of drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a crushing process and a wet-milling process to obtain the silicon-containing organic resin particles. In this way, the silicon-containing organic resin particles with a secondary particle morphology can be obtained.

[0159] In other embodiments, the method for providing the silicon-containing organic resin particles can further comprise a step of drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a baking process in an inert gas atmosphere, and then subjecting the baked product to a crushing process and a wet-milling process to obtain the silicon-containing organic resin particles. In this way, the silicon-containing organic resin particles with a secondary particle morphology having better heat resistance can be obtained.

[0160] In some embodiments, the drying of the product obtained from the emulsion polymerization can be performed by a method including, but not limited to, vacuum drying, spray drying, air blowing drying, microwave drying, or fluidized bed drying.

[0161] In some embodiments, the drying of the product obtained from the emulsion polymerization can be performed at a temperature ranging from 80°C to 150°C, for example, at 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, or a range defined by any two of the above values.

[0162] In some embodiments, the drying of the product obtained from the emulsion polymerization can be performed for a time period ranging from 2h to 12h, for example, for 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 a range defined by any two of the above values.

[0163] The baking can be performed in an inert gas atmosphere. In some embodiments, the inert gas can include one or more of nitrogen, argon, and helium.

[0164] In some embodiments, the baking can be performed at a temperature ranging from 160°C to 250°C, for example, at 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, or a range defined by any two of the above values.

[0165] In some embodiments, the time of baking can be 1h-8h, for example, 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, 5.2h, 5.4h, 5.6h, 5.8h, 6h, 6.2h, 6.4h, 6.6h, 6.8h, 7h, 7.2h, 7.4h, 7.6h, 7.8h, 8h, or a range composed of any of the above values. Alternatively, the time of baking can be 2h-8h, 2.4h-8h, 3h-8h.

[0166] In some embodiments, the crushing process can employ an air jet mill, a vibration mill, a mechanical crusher, an ultrasonic crusher, a ball mill, etc.

[0167] In some embodiments, the wet grinding process can include the following steps: mixing the material after the crushing process with a solvent, a grinding medium, and an optional dispersant to obtain a mixed slurry, and then grinding the mixed slurry to obtain the silicon-containing organic resin particles.

[0168] Alternatively, the solvent can include one or more of water, methanol, ethanol. More alternatively, the solvent can include water.

[0169] Alternatively, the dispersant can include one or more of a polyacrylic acid type dispersant, a carboxymethyl cellulose type dispersant, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone. Alternatively, the polyacrylic acid type dispersant can include one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, ammonium acrylate. Alternatively, the carboxymethyl cellulose type dispersant can include one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose.

[0170] Alternatively, the grinding medium can include one or more of zirconium oxide balls, aluminum oxide balls, silicon nitride balls.

[0171] Alternatively, the average particle size of the grinding medium can be 0.1mm-2mm.

[0172] Alternatively, the rotation speed of the grinding can be 500rpm-3000rpm.

[0173] In some embodiments, the emulsion polymerization reaction can include the following steps: under the conditions of a first temperature, inert gas protection, and stirring, the pre-emulsion is added dropwise into a reactor containing water, after a first reaction time, the temperature is raised to a second temperature for a second reaction time, to obtain the silicon-containing organic resin particles.

[0174] In some embodiments, the first temperature can be 55℃-70℃.

[0175] In some embodiments, the first time can be 3h-6h.

[0176] In some embodiments, the second temperature can be 72℃-92℃, for example, can be 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, or a range consisting of any of the foregoing.

[0177] In some embodiments, the second time can be 1h-5h, for example, 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 a range consisting of any of the foregoing.

[0178] The emulsion polymerization reaction is conducted under inert gas protection. In some embodiments, the inert gas can include one or more of nitrogen, argon, helium.

[0179] In some embodiments, the monomer can include a vinyl silane coupling agent and / or an acryloxy silane coupling agent.

[0180] Optionally, the monomer can include one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltri(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(β-methoxyethoxy)silane, ethylene tris[(1-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyl dimethyl ethoxysilane, methylvinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylvinyldimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0181] The crosslinking agent forms a crosslinking structure unit of the silicon-containing organic crosslinked resin after polymerization with the monomer.

[0182] In some embodiments, the crosslinking agent can be a multifunctional crosslinking agent.

[0183] Optionally, the crosslinking agent can include 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-trimethyladipylbis[2-ethylaziridine], 1,1-nonanedioylbis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-1-aziridinyl propionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate.

[0184] In some embodiments, the mass fraction of the crosslinking agent can be 1.5%-18%, for example, 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 a range consisting of any of the aforementioned values, based on the total mass of the monomer and the crosslinking agent being 100%.

[0185] The mass fraction of the crosslinking agent in the above range can obtain a silicon-containing organic resin particle with good heat resistance.

[0186] 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%, 8%-15%.

[0187] In some embodiments, the emulsifier can include, but is not limited to, one or more of alkyl sulfate, alkyl sulfonate, Tween emulsifier, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, cetyl stearyl alcohol polyether, oleyl alcohol polyether. Optionally, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, laureth-7, laureth-9, laureth-10, oleyl alcohol polyether-10.

[0188] In some embodiments, the initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisopropylimidazoline.

[0189] In some embodiments, the mass fraction of the initiator can be 0.15%-2.5%, for example, can be 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 a range consisting of any of the above numbers, based on 100% of the total mass of the monomer and the crosslinking agent. Alternatively, the mass fraction of the initiator can be 0.3%-2.1%, 0.3%-1.9%, 0.3%-1.7%, 0.3%-1.5%, 0.3%-1.3%.

[0190] In some embodiments, the pre-emulsion can further include a pH adjuster. Alternatively, the pH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia water, and the like.

[0191] The embodiments of the present disclosure further provide a secondary battery cell. The secondary battery cell includes the separator film provided by the present disclosure, or the separator film prepared by the method of the present disclosure. Thus, the secondary battery cell can have both high quality energy density and high reliability.

[0192] The secondary battery cell further includes a positive electrode tab, a negative electrode tab, and an electrolyte, and the separator film is disposed between the positive electrode tab and the negative electrode tab. The positive electrode tab, the separator film, and the negative electrode tab can form an electrode assembly through a rolling process and / or a stacking process.

[0193] The secondary battery cell provided by the present disclosure can include, but is not limited to, a lithium battery cell, a sodium battery cell, and the like. The composition of the positive electrode tab, the negative electrode tab, and the electrolyte can vary depending on the type of the secondary battery cell.

[0194] [Positive electrode tab]

[0195] In some embodiments, the positive electrode tab can include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0196] LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi0.5Mn1.5O4, LiNi0.5Co0.2Mn0.3O2 (NCM523), LiNi0.6Co0.2Mn0.2O2 (NCM622), LiNi0.8Co0.1Mn0.1O2 (NCM811), LiNi0.5Co0.2Al0.3O2, LiFePO4, LiMnPO4, and the like, and modified compounds of each of the foregoing. In some embodiments, to further enhance the energy density of the secondary battery cell, the positive active material can include one or more of lithium transition metal oxides of the general formula LiaNibCocMdOeAf and modified compounds thereof. 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.

[0197] As examples, the positive active material can include but is not limited to one or more of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi0.5Mn1.5O4, LiNi0.5Co0.2Mn0.3O2 (NCM523), LiNi0.6Co0.2Mn0.2O2 (NCM622), LiNi0.8Co0.1Mn0.1O2 (NCM811), LiNi0.5Co0.2Al0.3O2, LiFePO4, LiMnPO4, and the like, and modified compounds of each of the foregoing. 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 O2, LiFePO4, LiMnPO4, and the like.

[0198] The secondary battery cell will be accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the secondary battery cell is discharged to different states. In the disclosure, the molar content of Li in the listing of the positive electrode active material is the initial state of the material, i.e. the state before feeding, and the positive electrode active material is applied to the secondary battery cell. After charging and discharging cycles, the molar content of Li will change. In the disclosure, the molar content of O in the listing of the positive electrode active material is only the theoretical state value, and the lattice oxygen release will cause the molar content of O to change, and the actual molar content of O will also appear to float.

[0199] Taking a sodium battery cell as an example, the positive electrode active material can include but is not limited to one or more of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), prussian blue type materials. As an example, the positive electrode active material can include but is not limited to one or more of NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, prussian blue type materials, and materials of the general formula XpM’q(PO4)rOxY3-x. In the general formula XpM’q(PO4)rOxY3-x, 0

[0200] The modified compound of the positive electrode active material of each of the above lithium battery cell and sodium battery cell can be a doping modification and / or a surface coating modification of the positive electrode active material.

[0201] In some embodiments, the positive electrode film layer can further include a positive electrode conductive agent. As an example, the positive electrode conductive agent can include but is not limited to one or more of super conductive carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0202] In some embodiments, the positive electrode film layer can further include a positive electrode binder. As an example, the positive electrode binder can include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate-based resin.

[0203] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. As an example of the metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0204] The positive electrode film layer is generally formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is generally formed by dispersing and uniformly stirring a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and any other components in a solvent. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0205] [Negative electrode tab]

[0206] In some embodiments, the negative electrode tab can include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0207] The negative electrode active material can employ a material known in the art that can be used for a secondary battery cell. As an example, the negative electrode active material can include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material can include, but is not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and a silicon alloy material. The tin-based material can include, but is not limited to, one or more of elemental tin, tin oxide, and a tin alloy material.

[0208] In some embodiments, the negative electrode film layer can further include a negative electrode conductive agent. As an example, the negative electrode conductive agent can include, but is not limited to, one or more of super P, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0209] In some embodiments, the negative electrode film layer can further include a negative electrode binder. As an example, the negative electrode binder can include, but is not limited to, one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0210] In some embodiments, the negative electrode film layer can further include other auxiliary agents. As an example, the other auxiliary agents can include a thickening agent, such as sodium carboxymethyl cellulose (CMC), PTC thermistor material, etc.

[0211] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0212] The negative electrode film layer is generally formed by coating a negative electrode slurry on a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is generally formed by dispersing and uniformly stirring a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and other optional auxiliary agents in a solvent. The solvent can be N-methyl pyrrolidone (NMP) or deionized water, but is not limited thereto.

[0213] The negative electrode tab does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode tab further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) interposed between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0214] In some embodiments, the negative electrode tab can use a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When the foamed metal is used as the negative electrode tab, the surface of the foamed metal can not be provided with a negative electrode active material, and of course, can be provided with a negative electrode active material.

[0215] [Electrolyte]

[0216] The electrolyte serves to conduct ions between the positive electrode tab and the negative electrode tab.

[0217] In some embodiments, the electrolyte uses an electrolyte solution including an electrolyte salt and an organic solvent.

[0218] In the case of lithium battery cells, the electrolyte salt can include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium bisoxalato borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP).

[0219] In the case of sodium battery cells, the electrolyte salt can include, but is not limited to, one or more of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bis-trifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalato borate (NaDFOB), sodium bisoxalato borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalato phosphate (NaDFOP), and sodium tetrafluorooxalato phosphate (NaTFOP).

[0220] In some embodiments, the organic solvent can include, but is not limited to, one or more of 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), butylene 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, crown ether.

[0221] In some embodiments, an additive can also be included in the electrolyte. For example, the additive can include a negative electrode film-forming additive, can also include a positive electrode film-forming additive, and can also include an additive capable of improving certain properties of the secondary battery cell, such as an additive for improving overcharge performance, an additive for improving high-temperature performance, an additive for improving low-temperature performance, and the like.

[0222] Optionally, the additive can include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), and vinyl sulfate (DTD).

[0223] Methods for preparing secondary battery cells are well known. In some embodiments, a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte can be assembled to form a secondary battery cell. As an example, a positive electrode sheet, a separator, and a negative electrode sheet can be formed into an electrode assembly through a winding process and / or a stacking process, the electrode assembly can be placed in an outer package, an electrolyte described above can be injected after drying, and the secondary battery cell can be obtained through processes such as vacuum packaging, standing, and formation.

[0224] Embodiments

[0225] The present disclosure is described in more detail by the following examples, which are merely illustrative and not limiting upon the scope of the present disclosure, as various modifications and changes can be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported herein are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used without further purification, and the instruments used in the examples are commercially available.

[0226] Example 1

[0227] A pre-emulsion was prepared by emulsifying 0.3 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 52 g of γ-methacryloxypropyl triisopropoxysilane, 3 g of 3-methacryloxypropyl triethoxysilane, and 5 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 84°C for 1.5 h of curing reaction, and a slurry of silicon-containing organic resin particles 1# was obtained.

[0228] The above emulsion, nanocellulose fibers, binder polymethyl methacrylate, and dispersant sodium carboxymethyl cellulose were uniformly stirred in deionized water to obtain a porous coating slurry. The nanocellulose fibers had a length ranging from 2 μm to 5 μm and a diameter ranging from 20 nm to 50 nm. The solid mass ratio of silicon-containing organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry was 89:1:2:8.

[0229] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The porous coating slurry was coated on both surfaces of the porous base film by microgravure, and then dried and slitted to obtain a separator.

[0230] Example 2

[0231] The preparation method of the release film is the same as that of Example 1, except for the following differences.

[0232] The solid mass ratio of the silicon-containing organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry is 88:2:2:8.

[0233] Example 3

[0234] The preparation method of the release film is the same as that of Example 1, except for the following differences.

[0235] The solid mass ratio of the silicon-containing organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry is 87:3:2:8.

[0236] Example 4

[0237] The preparation method of the release film is the same as that of Example 1, except for the following differences.

[0238] The solid mass ratio of the silicon-containing organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry is 86:4:2:8.

[0239] Example 5

[0240] The preparation method of the release film is the same as that of Example 1, except for the following differences.

[0241] The solid mass ratio of the silicon-containing organic resin particles, nanocellulose fibers, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry is 85:5:2:8.

[0242] Comparative Example 1

[0243] A pre-emulsion was prepared by emulsifying 0.3g of sodium persulfate, 0.3g of sodium bicarbonate, 1.5g of sodium dodecyl sulfate, 30g of deionized water, and 60g of γ-methacryloxypropyl triisopropoxy silane. A reactor was taken and 210g of deionized water was added and heated to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring conditions. After 4h of reaction, the temperature was increased to 84°C for 1.5h of curing reaction to obtain a silicon-containing organic resin particle D1# slurry.

[0244] The above emulsion, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate were stirred and mixed uniformly in deionized water to obtain a porous coating slurry. The solid content mass ratio of the silicon-containing organic resin particles D1#, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the porous coating slurry was 90:2:8.

[0245] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The porous coating slurry was coated on both surfaces of the porous base film by microgravure coating, and then dried and slit to obtain the separator film.

[0246] Performance test

[0247] The heat shrinkage rate of the separator film can be tested according to GB / T 36363-2018.

[0248] The separator film was punched into a sample with a width of 50 mm and a length of 100 mm using a punch press, and 5 parallel samples were placed on an A4 paper. The A4 paper with the samples was then placed on corrugated paper with a thickness of 1 mm to 5 mm.

[0249] The temperature of the air-blast oven was set to 140℃, and after the temperature reached the set temperature and stabilized for 60 min, the A4 paper placed on the corrugated paper was placed in the air-blast oven, and the timing was started. After the set time (1 h in the present disclosure) was reached, the length and width of the separator film were measured, and the values were marked as a and b, respectively.

[0250] Heat shrinkage rate calculation: longitudinal (MD) heat shrinkage rate = [(100-a) / 100] x 100%, transverse (TD) heat shrinkage rate = [(50-b) / 50] x 100%, and the average value of 3 parallel samples was taken as the test result.

[0251] Table 1

[0252] From the above test results, it can be seen that the separator film of the present disclosure has better heat resistance, and can improve the thermal safety performance of the secondary battery cell when used in the secondary battery cell.

[0253] It should be noted that the present disclosure is not limited to the above embodiments. The above embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect within the scope of the technical solution of the present disclosure are all included in the technical scope of the present disclosure. In addition, within the scope of the main idea of the present disclosure, various modifications that can be thought of by those skilled in the art, and other ways constructed by combining part of the components in the embodiments are also included in the scope of the present disclosure.

Claims

1. An isolation membrane comprising a porous base membrane and a porous coating on at least one side of the porous base membrane, wherein, The porous coating includes silicon-containing organic resin particles and fibrous material, and at least a part of the silicon-containing organic resin particles is located between the fibrous material.

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

3. The separator film according to any one of claims 1-2, wherein, The silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles contain carbon-carbon bonds and siloxane structures.

4. The separator film according to any one of claims 1 to 3, wherein The silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles are network structures formed with carbon-carbon bonds as the main chain, and the side chains contain siloxane structures and benzene ring structures.

5. The separator film according to any one of claims 1 to 4, wherein The silicon-containing organic resin particles are silicon-containing organic crosslinked resin particles, and the silicon-containing organic resin particles include crosslinking structure units. Optionally, the crosslinking structure units include one or more of divinylbenzene structure units, diethylene glycol divinyl ether structure units, triethylene glycol divinyl ether structure units, maleic acid diallyl ester structure units, ethylene glycol dimethyl acrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethyl adipoyl bis[2-ethylaziridine] structure units, 1,1-sebacoyl bis[2-methylaziridine] structure units, 1,1-(1,3-phenylene dicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tri(3-aziridinyl) propionate structure units.

6. The separator film according to any one of claims 1 to 5, wherein 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 silicon-containing organic resin particles have a dissolution rate of 3% or less when 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; (3) The silicon-containing organic resin particles have a swelling degree of 3% or less when 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; (4) The silicon-containing organic resin particles have no oxidation peak in the voltage range of 2.50V to 4.40V in the cyclic voltammogram of the first cycle.

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

8. The separator film according to any one of claims 1 to 7, wherein 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 film according to any one of claims 1 to 8, wherein The fibrous material includes one or more of sugar-based fibers, protein-based fibers, polymer fibers, and inorganic fibers. Optionally, the fibrous material comprises one or more of alginic acid and its derivative fibers, nanocellulose and its derivative fibers, chitosan and its derivative fibers, chitin and its derivative fibers, vegetable cellulose, silk fibroin fibers, spider silk protein fibers, corn protein fibers, soy 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 terephthalate fibers, polyethylene terephthalate fibers, polyphenylene terephthalamide fibers, glass fibers, asbestos fibers, silica fibers.

10. The separator film according to any one of claims 1 to 9, wherein The fibrous material has a polar group; Optionally, the polar group comprises one or more of a hydroxyl group, a carboxyl group, an ester group, an amide group, a cyano group, an amine group, an aldehyde group, a sulfonic acid group, a boronic acid group, a phosphoric acid group.

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

12. The separator film according to any one of claims 1 to 11, wherein, the porous coating further comprises a binder; and / or, a thickness of the porous coating is 0.5 μm to 5 μm.

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

14. The method of claim 13, wherein, The method for providing the silicon-containing organic resin particles comprises the steps of: providing a pre-emulsion comprising monomers, a crosslinking agent, an emulsifier, an initiator, and water, the monomers comprising a silane coupling agent containing an alkenyl group and / or an acryloyloxy group; and subjecting the pre-emulsion to emulsion polymerization under heating, inert gas protection, and stirring to obtain the silicon-containing organic resin particles.

15. The method of claim 14, wherein, The method further comprises the steps of: drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a crushing process and a wet grinding process to obtain the silicon-containing organic resin particles.

16. The method of claim 14, wherein, The method further comprises the steps of: drying the product obtained from the emulsion polymerization, and then subjecting the dried product to a crushing process and a wet grinding process to obtain the silicon-containing organic resin particles.

17. The method according to any one of claims 14 to 16, wherein, one or more of gamma-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, gamma-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltris(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(beta-methoxyethoxy)silane, ethylene tris[(1-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyl dimethyl ethoxysilane, methylvinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylvinyldimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane; and / or, 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-trimethylhexanedioic acid bis[2-ethylaziridine], 1,1-nonanedioic acid bis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-1-aziridinylpropionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate; and / or, a mass fraction of the crosslinking agent is 1.5%-18%, based on a total mass of the monomer and the crosslinking agent being 100%.

18. The method of any one of claims 14-17, wherein, the emulsion polymerization reaction comprises the following steps: under the conditions of a first temperature, inert gas protection and stirring, the pre-emulsion is added dropwise into a reactor containing water, after a first time of reaction, the temperature is raised to a second temperature for a second time of reaction, and then silicon-containing organic resin particles are obtained.

19. The method of claim 18, wherein, the first temperature is 55°C-70°C; and / or, the first time is 3h-6h; and / or, the second temperature is 72°C-92°C; and / or, the second time is 1h-5h; and / or, The inert gas includes one or more of nitrogen, argon, and helium.

20. A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator film according to any one of claims 1 to 12, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

21. A battery device comprising a plurality of the secondary battery cell according to claim 20.

22. An electrically powered device comprising the secondary battery cell according to claim 20 or the battery device according to claim 21.

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