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

Abstract

A separator and a preparation method therefor, a secondary battery cell, a battery device, and an electric device. The separator comprises a porous base membrane and a porous coating located on at least one side of the porous base membrane. The porous coating comprises organic particles and inorganic particles, and the mass proportion of the organic particles in the porous coating is greater than the mass proportion of the inorganic particles in the porous coating. The separator is used in a secondary battery cell, such that the secondary battery cell has both high 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. 202411385150.9, 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 energy density and high reliability.

[0006] In a first aspect, the present disclosure provides a separator, comprising 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 organic particles and inorganic particles, and the mass fraction of the organic particles in the porous coating layer is greater than the mass fraction of the inorganic particles in the porous coating layer.

[0007] The density of the organic particles is small, and the mass fraction of the organic particles in the porous coating layer is greater than the mass fraction of the inorganic particles in the porous coating layer, so that the secondary battery cell using the separator of the present disclosure can have higher energy density. By making the porous coating layer of the separator simultaneously comprise organic particles and inorganic particles, the heat resistance of the porous coating layer as a whole can also be improved, the thermal shrinkage of the separator as a whole can be reduced, and the reliability of the secondary battery cell can be improved. Therefore, the separator of the present disclosure can make the secondary battery cell have high energy density and high reliability.

[0008] In some embodiments, the mass fraction of the organic particles in the porous coating layer is 50%-93%, which can be 60%-88%.

[0009] In some embodiments, the mass fraction of the inorganic particles in the porous coating layer is 5%-45%, which can be 10%-30%.

[0010] The mass content of the inorganic particles in the porous coating is within the above range, which can make the secondary cell have better heat resistance and higher energy density.

[0011] In some embodiments, the cyclic voltammogram of the organic particles in the first cycle has no oxidation peak in the voltage range of 2.5V to 4.4V. The cyclic voltammogram of the organic particles in the first cycle has no oxidation peak in the voltage window range of greater than or equal to 2.5V and less than 4.4V, indicating that the organic particles are stable in the voltage window range of greater than or equal to 2.5V and less than 4.4V and do not undergo electrochemical redox reactions, so that the secondary battery cell provided by the embodiments of the present disclosure can have a high voltage platform and high energy density.

[0012] In some embodiments, the swelling degree of the organic particles is less than or equal to 3% when soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days. The organic particles have a small swelling degree in the organic solvent, and the structural stability of the organic particles is high during long-term use of the secondary battery cell, thereby improving the problem of the decrease in the air permeability of the separator film during use.

[0013] In some embodiments, the dissolution rate of the organic particles is less than or equal to 3% when soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days. The organic particles have a small dissolution rate in the organic solvent, and the structural stability of the organic particles is high during long-term use of the secondary battery cell, and the chemical stability of the organic particles in the electrolyte is high, so that the secondary battery cell can have longer cycle stability.

[0014] In some embodiments, the organic particles have no melting point. The organic particles have no melting point, indicating that the organic particles have good heat resistance and thermal stability. By locating the organic particles on the porous base film, when the porous base film changes from a glass state to a high-elastic state, the porous coating is still stable, and the organic particles in the porous coating can better generate a force to resist the shrinkage of the porous base film, thereby improving the overall thermal shrinkage of the separator film and improving the heat resistance of the separator film.

[0015] In some embodiments, the initial thermal weight loss temperature T 3d of the organic particles is greater than or equal to 240°C. The initial thermal weight loss temperature T 3d of the organic particles is high, indicating that the organic particles have good thermal stability, thereby better resisting the thermal shrinkage of the porous base film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0016] In some embodiments, the true density of the organic particles is 1.0g / cm 3 -2.0g / cm 3 .

[0017] In some embodiments, the inorganic particles have a true density of 2.5 g / cm3 3 - 3.5 g / cm3 3 .

[0018] In some embodiments, the organic particles include at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a cross-linked polymer.

[0019] In some embodiments, the thermoplastic resin polymer includes one or more of polycarbonate-based organic particles, polymethyl acrylate methyl ester-based organic particles, polyformaldehyde-based organic particles, polyamide-based organic particles, styrene-acrylonitrile copolymer, polyphenylene sulfide-based organic particles, polyether ether ketone-based organic particles, polyimide-based organic particles, polysulfone-based organic particles, polyether sulfone-based organic particles, polyphenylene sulfone-based organic particles, polybenzimidazole-based organic particles, polyamide-imide-based organic particles, polyethylene imine-based organic particles.

[0020] In some embodiments, the thermosetting resin polymer includes one or more of phenol resin-based organic particles, polymer particles containing triazine ring structural units, epoxy resin-based organic particles, unsaturated polyester resin-based organic particles, urea-formaldehyde resin-based organic particles, furan resin-based organic particles.

[0021] In some embodiments, the cross-linked polymer includes one or more of cross-linked styrene-based organic particles, silicon-containing organic cross-linked resin particles.

[0022] In some embodiments, the organic particles include one or more of cross-linked styrene-based organic particles, silicon-containing organic cross-linked resin particles, phenol resin-based organic particles, polymer particles containing triazine ring structural units.

[0023] In some embodiments, the organic particles include cross-linked styrene-based organic particles, and the cross-linked styrene-based organic particles include styrene or styrene derivative structural units and cross-linking structural units.

[0024] Optionally, the styrene or styrene derivative structural units include one or more of styrene structural units, 1-methyl-1-styrene structural units, 4-methylstyrene structural units, 2-methylstyrene structural units, 2,4-dimethylstyrene structural units, 2,5-dimethylstyrene structural units.

[0025] Optionally, the crosslinking structure unit includes one or more of a divinylbenzene structure unit, an ethylene glycol dimethacrylate structure unit, a pentaerythritol tetraacrylate structure unit, a 1,4-butanediol diacrylate structure unit, a 1,6-hexanediol diacrylate structure unit, a 1,8-octanediol diacrylate structure unit, a trimethylolpropane triacrylate structure unit, a pentaerythritol trimethacrylate structure unit, a tetraethylene glycol dimethacrylate structure unit, a tripropylene glycol diacrylate structure unit, an N,N-methylenebisacrylamide structure unit, an N,N'-vinylbisacrylamide structure unit, a 1,3,5-triacryloylhexahydro-1,3,5-triazine structure unit, and a trimeric isocyanuric acid triallyl ester structure unit.

[0026] In some embodiments, the organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles have a glass transition temperature T g is 110°C-165°C. By using the crosslinked styrene-based organic particles of the present disclosure in the separator film, the crosslinked styrene-based organic particles can better generate a force that resists shrinkage of the separator film, thereby improving the thermal shrinkage of the entire separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0027] In some embodiments, the organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles have an initial thermal weight loss temperature T 3d is 335°C-388°C.

[0028] In some embodiments, the organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles have a volume distribution particle size Dv50 of 80 nm-300 nm. The volume distribution particle size Dv50 of the crosslinked styrene-based organic particles in the above range is advantageous for the porous coating layer of the separator film to have good heat resistance and air permeability.

[0029] In some embodiments, the organic particles include silicon-containing organic crosslinking resin particles, and the silicon-containing organic crosslinking resin particles contain a benzene ring structure.

[0030] Optionally, the silicon-containing organic crosslinking 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.

[0031] In some embodiments, the organic particles comprise silicon-containing organic crosslinked resin particles, wherein the silicon-containing organic crosslinked resin particles comprise crosslinked structural units, and the crosslinked structural units comprise divinylbenzene structural units. Optionally, the crosslinked structural units further comprise diethylene glycol divinyl ether structural units, triethylene glycol divinyl ether structural units, diallyl maleate structural units, ethylene glycol dimethacrylate structural units, 1,4-butanediol diacrylate structural units, 1,6-hexanediol diacrylate structural units, 1,8-octanediol diacrylate structural units, trimethylolpropane triacrylate structural units, pentaerythritol trimethacrylate structural units, tetraethylene glycol dimethacrylate structural units, and tripropylene glycol diacetate structural units. One or more of the following structural units: diacrylate, 2,2,4-trimethyladipyldi[2-ethylaziridinium], 1,1-azeloyldi[2-methylaziridinium], 1,1-(1,3-phenylene dicarbonyl)di[2-methylaziridinium], trimethylolpropane tris(2-methyl-1-aziridinium propionate), trimethylolpropane tris[3-(2-methylaziridinium)propionate], and pentaerythritol tris(3-aziridinium)propionate.

[0032] In some embodiments, the organic particles comprise silicon-containing organic crosslinked resin particles, and the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles is 80 nm-800 nm. A volume distribution particle size Dv50 within this range is beneficial for the porous coating of the separator to possess good heat resistance and air permeability.

[0033] In some embodiments, the organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles have no glass transition temperature below 300°C. The fact that the silicon-containing organic crosslinked resin particles have no glass transition temperature below 300°C indicates that they have good heat resistance and thermal stability, thereby better resisting the thermal shrinkage of the porous base film, improving the heat resistance of the separator, and enhancing the reliability of the secondary battery cell.

[0034] In some embodiments, the organic particles comprise silicon-containing organic crosslinked resin particles, and the initial thermogravimetric temperature T of the silicon-containing organic crosslinked resin particles is... 3d The temperature range is 240℃-330℃.

[0035] In some embodiments, the organic particles include phenolic resin organic particles, and the phenolic resin organic particles are thermosetting propylene resins.

[0036] In some embodiments, the organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles have no glass transition temperature below 300°C. The phenolic resin-based organic particles have no glass transition temperature below 300°C, which means that the phenolic resin-based organic 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.

[0037] In some embodiments, the organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles have an initial thermal weight loss temperature T 3d of 300°C-350°C.

[0038] In some embodiments, the organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles have a volume distribution particle size Dv50 of 160 nm-800 nm. The volume distribution particle size Dv50 of the phenolic resin-based organic particles in the above range is conducive to the porous coating of the separator film having good heat resistance and air permeability.

[0039] In some embodiments, the organic particles include polymer particles containing triazine ring structural units, and the polymer particles containing triazine ring structural units include a bridging structure connecting the triazine ring structural units.

[0040] In some embodiments, the bridging structure includes one or a combination of two or more of an alkylene group, an alkylene ether group, an alkylene amine group, an ester group, and an amide group.

[0041] In some embodiments, the polymer particles containing triazine ring structural units further have a substituent on the triazine ring structural units, and the substituent includes one or a combination of two or more of an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an amine group, a hydroxyl group, and a halogen.

[0042] In some embodiments, the organic particles include polymer particles containing triazine ring structural units, and the polymer particles containing triazine ring structural units have no glass transition temperature below 300°C. The polymer particles containing triazine ring structural units have no glass transition temperature below 300°C, which means that the polymer particles containing triazine ring structural units 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.

[0043] In some embodiments, the organic particles include polymer particles containing triazine ring structural units, and the polymer particles containing triazine ring structural units have an initial thermal weight loss temperature T 3d of 290°C-340°C.

[0044] In some embodiments, the organic particles include polymer particles containing triazine ring structural units, and the polymer particles containing triazine ring structural units have a volume distribution particle size Dv50 of 160 nm to 800 nm. The volume distribution particle size Dv50 of the polymer particles containing triazine ring structural units within the above range is advantageous for the porous coating of the separation membrane to have good heat resistance and air permeability.

[0045] In some embodiments, the polymer particles containing triazine ring structural units include at least one of melamine formaldehyde polymers and derivatives thereof, etherified melamine formaldehyde polymers and derivatives thereof, etherified melamine formaldehyde-polyol polymers and derivatives thereof, etherified melamine formaldehyde-polybasic acid polymers and derivatives thereof, and etherified melamine formaldehyde-polyamine amide polymers and derivatives thereof.

[0046] In some embodiments, the melamine formaldehyde polymers and derivatives thereof include one or more of melamine formaldehyde, benzotriazine formaldehyde, melamine-benzotriazine formaldehyde, melamine-(2,4-diamino-1,3,5-triazine) formaldehyde, melamine-(6-methyl-1,3,5-triazine-2,4-diamine) formaldehyde, melamine-(2,4,6-triethylamino-1,3,5-triazine) formaldehyde, trihydrazinyl-s-triazine formaldehyde, melamine-(2-amino-4-methylamino-1,3,5-triazine) formaldehyde, and melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde.

[0047] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof include one or more of methyl etherified melamine formaldehyde, butyl etherified melamine formaldehyde, methyl etherified benzotriazine formaldehyde, and butyl etherified benzotriazine formaldehyde.

[0048] In some embodiments, the etherified melamine formaldehyde-polyol polymers and derivatives thereof include one or more of methyl etherified melamine formaldehyde-ethylene glycol polymer, methyl etherified melamine formaldehyde-1,2-propanediol polymer, methyl etherified melamine formaldehyde-1,4-butanediol polymer, methyl etherified melamine formaldehyde-polyester polyol polymer, methyl etherified melamine formaldehyde-polyvinyl alcohol polymer, butyl etherified melamine formaldehyde-ethylene glycol polymer, butyl etherified melamine formaldehyde-1,2-propanediol polymer, butyl etherified melamine formaldehyde-1,4-butanediol polymer, and butyl etherified melamine formaldehyde-polyester polyol polymer.

[0049] In some embodiments, the etherified melamine aldehyde-polycarboxylic acid polymer and derivatives thereof include one or more of a methyl etherified melamine formaldehyde-oxalic acid polymer, a methyl etherified melamine formaldehyde-malic acid polymer, a methyl etherified melamine formaldehyde-succinic acid polymer, a methyl etherified melamine formaldehyde-citric acid polymer, a methyl etherified melamine formaldehyde-terephthalic acid polymer, a methyl etherified melamine formaldehyde-phthalic acid polymer, a butyl etherified melamine formaldehyde-oxalic acid polymer, a butyl etherified melamine formaldehyde-malic acid polymer, a butyl etherified melamine formaldehyde-citric acid polymer, a butyl etherified melamine formaldehyde-terephthalic acid polymer, and a butyl etherified melamine formaldehyde-phthalic acid polymer.

[0050] In some embodiments, the etherified melamine aldehyde-polyamine amide polymer and derivatives thereof include one or more of a methyl etherified melamine formaldehyde-oxamide polymer, a methyl etherified melamine formaldehyde-malonic amide polymer, a methyl etherified melamine formaldehyde-isophthalic amide polymer, and a butyl etherified melamine formaldehyde-oxamide polymer.

[0051] In some embodiments, the inorganic particles have a volume distribution particle size Dv50 of 200 nm to 800 nm.

[0052] In some embodiments, the inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, or inorganic particles capable of electrochemical reaction.

[0053] In some embodiments, the porous coating further includes a binder.

[0054] In some embodiments, the porous coating has a thickness of 0.5 μm to 5 μm.

[0055] In a second aspect, the present disclosure provides a method for preparing a separator film, including the following steps: providing a porous base film; providing a slurry including organic particles, inorganic particles, and a binder; coating the slurry on at least one side of the porous base film to obtain a separator film after drying.

[0056] In a third aspect, the present disclosure provides a secondary battery cell including a positive electrode sheet, a negative electrode sheet, and the separator film of the first aspect of the present disclosure, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

[0057] In a fourth aspect, the present disclosure provides a battery device including a plurality of the secondary battery cell of the third aspect of the present disclosure.

[0058] In a fifth aspect, the present disclosure provides an electric device including 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

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments of the present disclosure. Obviously, the drawings described below are only some of the embodiments of the present disclosure, and other drawings can also be obtained by the drawings without paying creative labor.

[0060] FIG. 1 shows a schematic diagram of a secondary battery cell according to some embodiments of the present disclosure.

[0061] FIG. 2 shows a schematic diagram of an electrical device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0062] Hereinafter, specific embodiments of the present disclosure, i.e., a separator and a method for manufacturing the same, a secondary battery cell, a battery device, and an electrical 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 well-known in the art, repeated descriptions of substantially identical configurations, are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0063] The ranges disclosed in the present disclosure are defined in the form of lower limit and upper limit, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is 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" represents a shorthand manner of describing the arbitrary real number combinations between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand notation for these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0064] If not particularly specified, all the 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.

[0065] If not particularly specified, all the 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.

[0066] If not particularly specified, all the 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) performed in sequence, or steps (b) and (a) performed 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.

[0067] If not particularly specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects, rather than to describe a specific order or primary and secondary relationship.

[0068] In the present disclosure, the terms "a plurality of" and "a plurality of" refer to two or more.

[0069] In the description of the embodiments of the present disclosure, if not particularly specified, 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 or above 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 or below 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.

[0070] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25℃.

[0071] 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.

[0072] The secondary battery cell provided by embodiments of the present disclosure can include, but is not limited to, a lithium battery cell, a sodium battery cell, for example, a lithium-ion battery cell, a sodium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, etc.

[0073] The secondary battery cell provided by embodiments of the present disclosure includes an electrode assembly. The electrode assembly can be in a jelly-roll structure or in a stacked structure, and embodiments of the present disclosure are not limited in this regard. The secondary battery cell further includes an outer package, which can be used to encapsulate 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 pouch-type soft package. The soft package can be made of plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0074] The battery apparatus mentioned by 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 connection through a busbar component.

[0075] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of secondary battery cells.

[0076] 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 an independent module. As an example, the battery module can be formed by bundling a plurality of secondary battery cells with a cable tie.

[0077] In some embodiments, the battery apparatus can be a battery pack, which includes a box and one or more battery cell assemblies accommodated in the box.

[0078] As an example, the battery cell assembly can be a battery module, which can be accommodated in the box by fixing the battery module in the box.

[0079] As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of secondary battery cells in the box.

[0080] As an example, the box can include a first box and a second box. The first box and the second box are buckled so that a closed space is formed inside the box to accommodate the battery cell assembly. Here, closed means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0081] As an example, the box can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are connected with the frame, respectively, so that an enclosed space is formed inside the box to accommodate the battery cell assembly.

[0082] In some embodiments, the box can be part of a chassis structure of a vehicle. For example, part of the box can be at least part of a floor of the vehicle, or part of the box can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0083] 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.

[0084] 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.

[0085] In the context of the present disclosure, the "organic particles" mainly play a role in improving the heat resistance in the porous coating of the separator film, and almost have no adhesion.

[0086] The separator film is an important component for supporting the secondary battery cell to complete the electrochemical process of charging and discharging. The commonly used separator film is mostly a polyolefin film. However, the polyolefin film has poor heat resistance and is easy to soften or melt at high temperature, which may cause a 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 commonly used heat-resistant fillers. However, the density of such heat-resistant fillers is large, and the mass is large under the same packing volume, which affects the energy density of the secondary battery cell.

[0087] Based on this, the embodiments of the present disclosure provide a separator film used in a secondary battery cell, which can make the secondary battery cell have high energy density and high reliability.

[0088] The separator film of the present disclosure includes a porous base film and a porous coating layer located on at least one side of the porous base film. The porous coating layer includes organic particles and inorganic particles, and the mass proportion of the organic particles in the porous coating layer is greater than the mass proportion of the inorganic particles in the porous coating layer.

[0089] Both the porous base film and the porous coating layer have a pore structure, so that the separator film has good air permeability and facilitates ion passage. The density of the organic particles is small, and the mass proportion of the organic particles in the porous coating layer is greater than the mass proportion of the inorganic particles in the porous coating layer, so that the secondary battery cell using the separator film of the present disclosure has a higher energy density. By having the porous coating layer of the separator film simultaneously include organic particles and inorganic particles, the heat resistance of the entire porous coating layer can also be improved, the thermal shrinkage of the entire separator film is reduced, and the reliability of the secondary battery cell is improved. Therefore, the separator film of the present disclosure can make the secondary battery cell have both high energy density and high reliability.

[0090] In some embodiments, the true density of the organic particles can be 1.0 g / cm 3 -2.0 g / cm 3 .

[0091] In some embodiments, the true density of the inorganic particles can be 2.5 g / cm 3 -3.5 g / cm 3 .

[0092] In some embodiments, the mass proportion of the organic particles in the porous coating layer can be 50%-93%, for example, can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 93%, or a range consisting of any of the above values.

[0093] Alternatively, the mass proportion of the organic particles in the porous coating layer can be 60%-88%.

[0094] In some embodiments, the mass proportion of the inorganic particles in the porous coating layer can be 5%-45%, for example, can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 45%, or a range consisting of any of the above values.

[0095] Alternatively, the mass proportion of the inorganic particles in the porous coating layer can be 10%-30%.

[0096] The density of the inorganic particles is large, and the mass is large under the same packing volume. The mass content of the inorganic particles in the porous coating layer is in the above range, so that the secondary cell has both good heat resistance and high energy density.

[0097] In some embodiments, the cyclic voltammogram of the organic particles in the first cycle does not have an oxidation peak in the voltage range of 2.5V to 4.4V.

[0098] The cyclic voltammogram of the first cycle of the organic particle has no oxidation peak in the voltage window range of greater than or equal to 2.5 V and less than 4.4 V, indicating that the organic particle is stable in the voltage window range of greater than or equal to 2.5 V and less than 4.4 V and no electrochemical redox reaction occurs, thereby enabling the secondary battery cell provided by the embodiments of the present disclosure to have a high voltage platform and a high energy density.

[0099] In some embodiments, the swelling degree of the organic particle immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%.

[0100] The swelling degree of the organic particle in the organic solvent is small, and the structural stability of the organic particle during long-term use of the secondary battery cell is high, thereby improving the problem of the decrease in the air permeability of the separator during use.

[0101] In some embodiments, the dissolution rate of the organic particle immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days is less than or equal to 3%.

[0102] The dissolution rate of the organic particle in the organic solvent is small, and the structural stability of the organic particle during long-term use of the secondary battery cell is high, and the chemical stability of the organic particle in the electrolyte is high, thereby enabling the secondary battery cell to have a longer cycle stability.

[0103] In some embodiments, the organic particle has no melting point.

[0104] The organic particle of the present disclosure has no melting point, indicating that the heat resistance and thermal stability of the organic particle are good. By locating the organic particle on the porous base film, when the porous base film is transformed from a glassy state to a high-elastic state, the porous coating is still stable, and the organic particle in the porous coating can better generate a force resisting the shrinkage of the porous base film, thereby improving the overall thermal shrinkage of the separator and improving the heat resistance of the separator.

[0105] In some embodiments, the initial thermal weight loss temperature T 3d of the organic particle can be greater than or equal to 240°C. The initial thermal weight loss temperature T 3d of the organic particle is high, indicating that the thermal stability of the organic particle is good, thereby better resisting the thermal shrinkage of the porous base film, improving the heat resistance of the separator, and improving the reliability of the secondary battery cell.

[0106] In some embodiments, the organic particle can include at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a cross-linked polymer.

[0107] In some embodiments, the thermoplastic resin polymer can include one or more of polycarbonate-based organic particles, polymethacrylate methyl ester-based organic particles, polyformaldehyde-based organic particles, polyamide-based organic particles, styrene-acrylonitrile copolymers, polyphenylene sulfide-based organic particles, polyether ether ketone-based organic particles, polyimide-based organic particles, polysulfone-based organic particles, polyether sulfone-based organic particles, polyphenylene sulfone-based organic particles, polybenzimidazole-based organic particles, polyamide-imide-based organic particles, polyethyleneimine-based organic particles.

[0108] In some embodiments, the thermosetting resin polymer can include one or more of phenol formaldehyde resin-based organic particles, polymer particles containing triazine ring structural units, epoxy resin-based organic particles, unsaturated polyester resin-based organic particles, urea-formaldehyde resin-based organic particles, furan resin-based organic particles.

[0109] In some embodiments, the cross-linked polymer can include one or more of cross-linked styrene-based organic particles, silicon-containing organic cross-linked resin particles.

[0110] In some embodiments, the organic particles can include one or more of cross-linked styrene-based organic particles, silicon-containing organic cross-linked resin particles, phenol formaldehyde resin-based organic particles, polymer particles containing triazine ring structural units.

[0111] The above organic particles are neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e., not soluble in the mobile phase for gel permeation chromatography testing, nor can the molecular weight of the organic particles be tested by gel permeation chromatography.

[0112] [Cross-linked styrene-based organic particles]

[0113] In some embodiments, the cross-linked styrene-based organic particles include styrene or styrene derivative structural units and cross-linking structural units.

[0114] Optionally, the styrene or styrene derivative structural units can include one or more of styrene structural units, 1-methyl-1-styrene structural units, 4-methylstyrene structural units, 2-methylstyrene structural units, 2,4-dimethylstyrene structural units, 2,5-dimethylstyrene structural units.

[0115] Optionally, the crosslinking structural unit can include one or more of a divinylbenzene structural unit, a ethylene glycol dimethacrylate structural unit, a pentaerythritol tetraacrylate 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 N,N-methylenebisacrylamide structural unit, a N,N'-vinylbisacrylamide structural unit, a 1,3,5-triacryloylhexahydro-1,3,5-triazine structural unit, and a trimeric isocyanuric acid triallyl ester structural unit.

[0116] In some embodiments, the glass transition temperature Tg of the crosslinked styrene-based organic particles is 110°C to 165°C. g may be 110°C to 165°C.

[0117] Currently, the glass transition temperature Tg of the non-crosslinked styrene-based organic particles and the commercially available crosslinked styrene-based organic particles is g usually below 100°C. The glass transition temperature Tg of the crosslinked styrene-based organic particles of the present disclosure is g 110°C to 160°C, which has a higher thermal stability. By using the crosslinked styrene-based organic particles of the present disclosure in the separator film, the crosslinked styrene-based organic particles can better generate a force to resist the shrinkage of the separator film, thereby improving the overall thermal shrinkage of the separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0118] In some embodiments, the initial thermal weight loss temperature T of the crosslinked styrene-based organic particles is 335°C to 388°C. 3d may be 335°C to 388°C.

[0119] In some embodiments, the cyclic voltammogram of the crosslinked styrene-based organic particles in the first cycle does not have an oxidation peak in a voltage range of 2.5V to 4.4V.

[0120] In some embodiments, the crosslinked styrene-based organic 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.

[0121] In some embodiments, the crosslinked styrene-based organic 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.

[0122] In some embodiments, the crosslinked styrene-based organic particles have no melting point.

[0123] In some embodiments, the volume distribution particle size Dv50 of the crosslinked styrene-based organic particles can be 80 nm-300 nm.

[0124] The volume distribution particle size Dv50 of the crosslinked styrene-based organic particles is within the above range, which is beneficial to the porous coating of the separator membrane to have good heat resistance and air permeability.

[0125] The crosslinked styrene-based organic particles are neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e. not soluble in the mobile phase for gel permeation chromatography test, nor can the molecular weight be tested by gel permeation chromatography.

[0126] [Silicon-containing organic crosslinking resin particles]

[0127] In some embodiments, the silicon-containing organic crosslinking resin particles contain a benzene ring structure.

[0128] At present, the existing silicon resin is mainly formed by hydrolysis of hydrolyzable siloxane to form a prepolymer, and then cured to obtain, and has poor heat resistance. The silicon-containing organic crosslinking resin particles of the present disclosure contain a benzene ring structure, and the benzene ring structure has strong rigidity, which can make the silicon-containing organic crosslinking resin particles have good heat resistance. By using the silicon-containing organic crosslinking resin particles containing a benzene ring structure in the porous coating of the separator membrane, a force resisting the shrinkage of the porous base film can be better generated, thereby the overall heat shrinkage of the separator membrane can be improved, the heat resistance of the separator membrane can be improved, and the reliability of the secondary battery cell can be improved.

[0129] Optionally, the silicon-containing organic crosslinking 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.

[0130] In some embodiments, the silicon-containing organic crosslinking resin particles include a crosslinking structure unit, and the crosslinking structure unit can include a divinylbenzene structure unit.

[0131] 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 diallyl maleate structural unit, a 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.

[0132] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic crosslinking resin particles can be 80 nm-800 nm.

[0133] The volume distribution particle size Dv50 of the silicon-containing organic crosslinking resin particles in the above range is beneficial to the porous coating of the separator membrane to have good heat resistance and air permeability.

[0134] In some embodiments, the silicon-containing organic crosslinking resin particles have no glass transition temperature below 300°C.

[0135] The silicon-containing organic crosslinking resin particles have no glass transition temperature below 300°C, indicating that they have good heat resistance and thermal stability, and thus can better resist the thermal shrinkage of the porous base film, improve the heat resistance of the separator membrane, and improve the reliability of the secondary battery cell.

[0136] In some embodiments, the silicon-containing organic crosslinking resin particles have a starting thermal weight loss temperature T 3d may be 240°C-330°C.

[0137] In some embodiments, the cyclic voltammogram of the silicon-containing organic crosslinking resin particles in the first cycle has no oxidation peak in the voltage range of 2.5V to 4.4V.

[0138] In some embodiments, the silicon-containing organic crosslinking resin particles have a swelling degree of less than or equal to 3% 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.

[0139] In some embodiments, the silicon-containing organic crosslinked resin particles have a dissolution rate of less than or equal to 3% 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.

[0140] In some embodiments, the silicon-containing organic crosslinked resin particles have no melting point.

[0141] The silicon-containing organic crosslinked resin particles are neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e. are insoluble in the mobile phase tested by gel permeation chromatography, nor can they be tested by gel permeation chromatography for molecular weight.

[0142] [Phenolic resin-based organic particles]

[0143] In some embodiments, the phenolic resin-based organic particles are thermosetting resins.

[0144] In some embodiments, the phenolic resin-based organic particles are thermosetting resol.

[0145] In some embodiments, the phenolic resin-based organic particles have no glass transition temperature below 300°C.

[0146] The fact that the phenolic resin-based organic particles have no glass transition temperature below 300°C indicates that they have good heat resistance and thermal stability, and thus can better resist the thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0147] In some embodiments, the phenolic resin-based organic particles have an initial thermal weight loss temperature T 3d may be 300-350°C.

[0148] In some embodiments, the phenolic resin-based organic particles have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.4V.

[0149] In some embodiments, the phenolic resin-based organic particles have a swelling degree of less than or equal to 3% 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.

[0150] In some embodiments, the phenolic resin-based organic particles have a dissolution rate of less than or equal to 3% 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.

[0151] In some embodiments, the phenolic resin-based organic particles have no melting point.

[0152] In some embodiments, the phenol resin-based organic particles can have a volume distribution particle size Dv50 of 160 nm to 800 nm.

[0153] The volume distribution particle size Dv50 of the phenol resin-based organic particles within the above range is advantageous for the porous coating of the separation membrane to have good heat resistance and air permeability.

[0154] The phenol resin-based organic particles are neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e., not soluble in the mobile phase for gel permeation chromatography testing, nor can the molecular weight be tested by gel permeation chromatography.

[0155] [Polymer particles containing triazine ring structure units]

[0156] The triazine ring structure is rigid, which can make the polymer particles have good heat resistance.

[0157] The polymer particles containing triazine ring structure units of the present disclosure include bridging structures connecting the triazine ring structure units.

[0158] The polymer particles containing triazine ring structure units have multiple triazine ring structure units in the molecular structure, and the bridging structure refers to a group connecting the triazine ring structure units, each bridging structure being the same or different.

[0159] Optionally, the bridging structure can include one or a combination of two or more of an alkylene group, an alkylene ether group, an alkylene amine group, an ester group, and an amide group.

[0160] More optionally, the bridging structure can include one or a combination of two or more of a methylene group, a methylene ether group, and a methylene amine group.

[0161] In some embodiments, the triazine ring structure units of the polymer particles containing triazine ring structure units can also have substituents, which can include a combination of one or more of an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an amine group, a hydroxyl group, and a halogen.

[0162] In some embodiments, the polymer particles containing triazine ring structure units can include at least one of melamine formaldehyde-based polymers and derivatives thereof, etherified melamine formaldehyde-based polymers and derivatives thereof, etherified melamine formaldehyde-polyol polymers and derivatives thereof, etherified melamine formaldehyde-polybasic acid polymers and derivatives thereof, and etherified melamine formaldehyde-polyamine amide polymers and derivatives thereof.

[0163] In some embodiments, the melamine formaldehyde-based polymers and derivatives thereof can include melamine formaldehyde polymers and derivatives thereof.

[0164] Optionally, the melamine formaldehyde polymers and derivatives thereof can include one or more of melamine formaldehyde, benzoguanamine formaldehyde, melamine- benzoguanamine formaldehyde, melamine-(2,4-diamino-l,3,5-triazine) formaldehyde, melamine-(6-methyl-l,3,5-triazine-2,4-diamine) formaldehyde, melamine-(2,4,6-triethylamino-l,3,5-triazine) formaldehyde, trihydrazinotriazine formaldehyde, melamine-(2-amino-4-methylamino-l,3,5-triazine) formaldehyde, melamine-(2,4-diamino-6-dimethylamino-l,3,5-triazine) formaldehyde.

[0165] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof can include etherified melamine formaldehyde polymers and derivatives thereof.

[0166] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof can include one or more of methyl etherified melamine formaldehyde polymers and derivatives thereof, ethyl etherified melamine formaldehyde polymers and derivatives thereof, butyl etherified melamine formaldehyde polymers and derivatives thereof, methyl-butyl mixed etherified melamine formaldehyde polymers and derivatives thereof.

[0167] Optionally, the etherified melamine formaldehyde polymers and derivatives thereof can include one or more of methyl etherified melamine formaldehyde polymers and derivatives thereof, ethyl etherified melamine formaldehyde polymers and derivatives thereof, butyl etherified melamine formaldehyde polymers and derivatives thereof, methyl-butyl mixed etherified melamine formaldehyde polymers and derivatives thereof.

[0168] The etherified melamine formaldehyde polymers and derivatives thereof can include one or more of partially etherified melamine formaldehyde polymers and derivatives thereof, fully etherified melamine formaldehyde polymers and derivatives thereof. Optionally, the etherified melamine formaldehyde polymers and derivatives thereof can include fully etherified melamine formaldehyde polymers and derivatives thereof.

[0169] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof can include one or more of methyl etherified melamine formaldehyde, butyl etherified melamine formaldehyde, methyl etherified benzoguanamine formaldehyde, butyl etherified benzoguanamine formaldehyde.

[0170] The etherified melamine formaldehyde-polyol polymers and derivatives thereof refer to the etherified melamine formaldehyde resin and polyol high temperature crosslinking and curing reaction products. Optionally, the molar ratio of the etherified melamine formaldehyde resin and polyol can be 1:2-1:6.

[0171] In some embodiments, the polyol can include one or more of dihydric alcohol, trihydric alcohol, tetrahydric alcohol. Optionally, the polyol can include one or more of ethylene glycol, 1,2-propanediol, 1,4-butanediol, neopentyl glycol, hexanediol, ethyl butyl propylene glycol, glycerol, trimethylolpropane, pentaerythritol, polyvinyl alcohol, polyether polyol, polyester polyol. More optionally, the polyol can include one or more of ethylene glycol, 1,2-propanediol, 1,4-butanediol, polyvinyl alcohol, polyester polyol.

[0172] Optionally, the polyester polyol can include one or more of polyethylene adipate glycol, poly-1,4-butanediol adipate glycol, polypropylene adipate glycol, polyneopentyl glycol adipate glycol, polyneopentyl glycol-1,6-hexanediol adipate glycol, polyhexanediol adipate glycol, polycarbonate glycol, polycaprolactone glycol.

[0173] Optionally, the polyether polyol can include one or more of polypropylene oxide diol, polypropylene oxide triol, polytetrahydrofuran diol.

[0174] Optionally, the molecular weight of the polyester polyol can be below 5000, optionally below 2000.

[0175] Optionally, the molecular weight of the polyether polyol can be below 5000, optionally below 2000.

[0176] Optionally, the molecular weight of the polyvinyl alcohol can be below 5000, optionally below 2000.

[0177] In some embodiments, the etherified melamine aldehyde-polyol polymer and its derivatives can include one or more of methyl etherified melamine formaldehyde-ethylene glycol polymer, methyl etherified melamine formaldehyde-1,2-propanediol polymer, methyl etherified melamine formaldehyde-1,4-butanediol polymer, methyl etherified melamine formaldehyde-polyester polyol polymer, methyl etherified melamine formaldehyde-polyvinyl alcohol polymer, butyl etherified melamine formaldehyde-ethylene glycol polymer, butyl etherified melamine formaldehyde-1,2-propanediol polymer, butyl etherified melamine formaldehyde-1,4-butanediol polymer, butyl etherified melamine formaldehyde-polyester polyol polymer.

[0178] The etherified melamine aldehyde-polybasic acid polymer and its derivatives refer to the etherified melamine aldehyde resin and polybasic acid high-temperature cross-linking and curing reaction product. Optionally, the molar ratio of the etherified melamine aldehyde resin and the polybasic acid can be 1:2-1:6.

[0179] In some embodiments, the polycarboxylic acid can include one or more of a dicarboxylic acid, a tricarboxylic acid, a tetracarboxylic acid. Optionally, the polycarboxylic acid can include one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, citric acid, tartaric acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic anhydride, 1,4-cyclohexane dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid. More optionally, the polycarboxylic acid can include one or more of oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid, terephthalic acid.

[0180] In some embodiments, the etherified melamine aldehyde-polycarboxylic acid polymer and its derivatives can include one or more of a methyl etherified melamine formaldehyde-oxalic acid polymer, a methyl etherified melamine formaldehyde-malonic acid polymer, a methyl etherified melamine formaldehyde-succinic acid polymer, a methyl etherified melamine formaldehyde-citric acid polymer, a methyl etherified melamine formaldehyde-terephthalic acid polymer, a methyl etherified melamine formaldehyde-phthalic acid polymer, a butyl etherified melamine formaldehyde-oxalic acid polymer, a butyl etherified melamine formaldehyde-malonic acid polymer, a butyl etherified melamine formaldehyde-citric acid polymer, a butyl etherified melamine formaldehyde-terephthalic acid polymer, a butyl etherified melamine formaldehyde-phthalic acid polymer.

[0181] The etherified melamine aldehyde-polycarboxylic acid polymer and its derivatives refer to the etherified melamine aldehyde resin and polycarboxylic acid high temperature crosslinking and curing reaction product. Optionally, the molar ratio of the etherified melamine aldehyde resin and polycarboxylic acid can be 1:2-1:6.

[0182] In some embodiments, the polycarboxylic acid can include one or more of a dicarboxylic acid, a tricarboxylic acid, a tetracarboxylic acid. Optionally, the polycarboxylic acid can include one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, citric acid, tartaric acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic anhydride, 1,4-cyclohexane dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid. More optionally, the polycarboxylic acid can include one or more of oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid, terephthalic acid.

[0183] In some embodiments, the etherified melamine aldehyde-polycarboxylic acid polymer and its derivatives can include one or more of a methyl etherified melamine formaldehyde-oxalic acid polymer, a methyl etherified melamine formaldehyde-malonic acid polymer, a methyl etherified melamine formaldehyde-succinic acid polymer, a methyl etherified melamine formaldehyde-citric acid polymer, a methyl etherified melamine formaldehyde-terephthalic acid polymer, a methyl etherified melamine formaldehyde-phthalic acid polymer, a butyl etherified melamine formaldehyde-oxalic acid polymer, a butyl etherified melamine formaldehyde-malonic acid polymer, a butyl etherified melamine formaldehyde-citric acid polymer, a butyl etherified melamine formaldehyde-terephthalic acid polymer, a butyl etherified melamine formaldehyde-phthalic acid polymer.

[0184] In some embodiments, the polymer particles containing triazine ring structure units have no glass transition temperature below 300°C.

[0185] The polymer particles containing the triazine ring structural unit have no glass transition temperature below 300°C, indicating good heat resistance and thermal stability, thereby better resisting thermal shrinkage of the porous base film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0186] In some embodiments, the polymer particles containing the triazine ring structural unit have an initial thermal weight loss temperature T 3d may be 290°C-340°C.

[0187] In some embodiments, the polymer particles containing the triazine ring structural unit have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.4V.

[0188] In some embodiments, the polymer particles containing the triazine ring structural unit have a swelling degree of less than or equal to 3% 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.

[0189] In some embodiments, the polymer particles containing the triazine ring structural unit have a dissolution rate of less than or equal to 3% 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.

[0190] In some embodiments, the polymer particles containing the triazine ring structural unit have no melting point.

[0191] In some embodiments, the volume distribution particle size Dv50 of the polymer particles containing the triazine ring structural unit can be 160nm-800nm.

[0192] The volume distribution particle size Dv50 of the polymer particles containing the triazine ring structural unit in the above range is beneficial to the porous coating of the separator film having good heat resistance and air permeability.

[0193] The polymer particles containing the triazine ring structural unit are neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e. not soluble in the mobile phase for gel permeation chromatography test, and cannot be tested for molecular weight by gel permeation chromatography.

[0194] [Inorganic particles]

[0195] In some embodiments, the volume distribution particle size Dv50 of the inorganic particles can be 200nm-800nm, optionally 200nm-700nm, 200nm-600nm, 200nm-500nm, 220nm-700nm, 220nm-600nm, 220nm-500nm.

[0196] In some embodiments, inorganic particles may include one or more of the following: inorganic particles having a dielectric constant of 5 or greater, inorganic particles having ion conductivity but not storing ions, or inorganic particles capable of undergoing electrochemical reactions.

[0197] In some embodiments, inorganic particles having a dielectric constant of 5 or higher may include boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxides, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, aluminum hydroxide, barium oxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, calcium fluoride, barium fluoride, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb (Mg3Nb) 2 / 3 The inorganic particles can be selected from one or more of PbTiO3 (PMN-PT) and their respective modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification.

[0198] In some embodiments, inorganic particles that are ion-conductive but do not store ions may include Li3PO4, lithium titanium phosphate (Li3PO4), etc. x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 O y3 Type glass, lithium lanthanum titanate (Li) x4 La y4 TiO3, lithium germanium thiophosphate (Li) x5 Ge y5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4One or more of the following are given: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can improve the ion conductivity of the separator.

[0199] In some embodiments, the inorganic particles capable of undergoing electrochemical reactions may include one or more of lithium-containing transition metal oxides, lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium-titanium compounds.

[0200] In some embodiments, the porous coating includes an adhesive, which may include, but is not limited to, one or more of polyacrylate adhesives, nitrile rubber adhesives, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0201] In some embodiments, the porous coating may further include a dispersant, such as one or more of alkylphenol polyoxyethylene ethers, polyacrylic acid dispersants, and cellulose dispersants, including but not limited to. As an example, the dispersant may include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0202] In some embodiments, the separator may also include polymer binder particles.

[0203] The "polymer binder particles" in the porous coating of the separator membrane play a role in improving the adhesion between the separator membrane and the electrode, but they have virtually no high-temperature resistance.

[0204] In some embodiments, polymer binder particles may be embedded in organic and inorganic particles and form protrusions on the surface of the porous coating.

[0205] In other embodiments, the porous coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on the porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer on the side away from the porous base membrane. Organic particles and inorganic particles are disposed in the heat-resistant layer, and polymer binder particles are disposed in the adhesive layer.

[0206] In some other embodiments, the porous coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on one side of the porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the other side of the porous base membrane. Organic particles and inorganic particles are disposed in the heat-resistant layer, and polymer binder particles are disposed in the adhesive layer.

[0207] In some embodiments, the average particle size of the polymeric binder particles can be 6 μm to 18 μm.

[0208] In some embodiments, the polymeric binder particles can include vinylidene fluoride-based polymeric particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and a comonomer.

[0209] 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 fluorinated ether monomer.

[0210] 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).

[0211] In some embodiments, the porous coating layer can have a thickness of 0.5 μm to 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 to 4 μm, 0.5 μm to 3 μm, 0.5 μm to 2 μm, 0.8 μm to 4 μm, 0.8 μm to 3 μm, 0.8 μm to 2 μm.

[0212] 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.

[0213] 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.

[0214] In some embodiments, the thickness of the porous base film can be 4 μm to 12 μm, and optionally 4 μm to 9 μm.

[0215] In some embodiments, the porosity of the porous base film can be 25% to 60%, and optionally 28% to 50%.

[0216] In some embodiments, the thickness of the isolation film can be 5-14 μm, optionally 5-12 μm, 6-12 μm. This is beneficial to improve the energy density of the secondary battery cell.

[0217] 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 the test, 1 g of the sample to be tested is added to a clean beaker, 20 ml of deionized water is added, and ultrasonic treatment is performed at 53 KHz / 120 W for 5 min to ensure complete dispersion of the sample. After turning on the laser particle size analyzer and cleaning the light path system, the background is automatically tested. The sample solution after ultrasonic treatment is stirred to disperse uniformly, and then placed in the sample cell according to the requirements, and the particle size is measured. The test instrument can be a MasterSizer 3000 laser particle size analyzer.

[0218] The glass transition temperature T g The test can be performed as follows: an appropriate amount of sample (e.g., 5-15 mg) is placed in a differential scanning calorimeter (DSC) crucible, leveled, and covered with a crucible cover. The parameters are set as follows: nitrogen atmosphere, purging gas 60 mL / min, and protective gas 20 mL / min. The program is set as follows: heating from 25 to 200℃ at a rate of 10℃ / min, holding for 5 min to eliminate thermal history, then cooling from 200 to -40℃ at a rate of 10℃ / min, and then heating from -40 to 300℃ at a rate of 10℃ / min. The glass transition temperature T g of the organic particles is obtained from the DSC curve. g .

[0219] The glass transition temperature T g is the transition temperature from glass state to high-elastic state, which shows a step change on the DSC curve.

[0220] The organic particles have no glass transition temperature T g below 300℃, which means that the DSC curve of the organic particles does not show a step change below 300℃.

[0221] The melting point can be tested as follows: take an appropriate amount of sample (for example, 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: temperature rise at a rate of 10°C / min from 25°C to 200°C, hold for 5 min to eliminate thermal history, then temperature drop at a rate of 10°C / min from 200°C to -40°C, then temperature rise at a rate of 10°C / min to 300°C. Determine from the DSC curve whether the organic particles have a melting point below 300°C. No melting point of the organic particles means that the DSC curve of the organic particles has no melting peak.

[0222] Onset thermal weight loss temperature T 3d The onset thermal weight loss temperature T refers to the temperature corresponding to a 3% loss in mass of the test sample relative to the initial mass. The onset thermal weight loss temperature T of the organic particles 3d The onset thermal weight loss temperature T can be tested as follows: take an appropriate amount of sample (for example, 5 mg-15 mg) and place it in an alumina crucible of a thermal gravimetric analyzer (TGA), shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; temperature rise program: temperature rise rate 10°C / min, temperature range 35°C-600°C; obtain from the test curve the temperature corresponding to a 3% loss in mass of the sample relative to the initial mass (i.e., 97% of the initial mass), which is the onset thermal weight loss temperature T 3d .

[0223] The oxidation peak potential of the cyclic voltammetry curve of the organic particles can be tested as follows: take the organic particles, the binder polymethyl methacrylate, and the conductive agent conductive carbon black, dissolve them in water according to a solid content mass ratio of 64:7:29 to prepare a slurry, coat the slurry on an aluminum foil as a positive electrode, use a lithium foil as a negative electrode, and assemble a coin cell. Perform cyclic voltammetry (CV) test on the coin cell at a scan rate of 0.10 mV / s, a voltage range of 2.50 V-5.00 V, and 3 cycles, and take the voltage corresponding to the peak point of the first cycle of the cyclic voltammetry curve as the oxidation peak potential. The electrolyte salt of the electrolyte used for testing is LiPF6, with a concentration of 1 mol / L, and the solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) according to a volume ratio of 3:7.

[0224] The swelling degree of the organic particles can be tested according to the following method: an appropriate amount of sample (for example, about 1 g) is taken, and the mass is recorded as m1, and the sample is placed in a semi-permeable membrane sample bag, which is sealed, and the sample bag can permeate the solvent but cannot permeate the sample; the sample bag is soaked in an appropriate amount of solvent (for example, about 50 g) at 60°C for 7 days, and then the sample bag is taken out, and the sample is taken out of the sample bag, the excess solvent is wiped off, and the mass of the sample is weighed again m2; the swelling degree = (m2-m1) / m1x100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0225] The dissolution rate of the organic particles can be tested according to the following method: an appropriate amount of sample (for example, about 1 g) is taken, and the mass is recorded as m1, and the sample is placed in a semi-permeable membrane sample bag, which is sealed, and the sample bag can permeate the solvent but cannot permeate the sample; the sample bag is soaked in an appropriate amount of solvent (for example, about 50 g) at 60°C for 7 days, and then the sample bag is taken out, and the sample is taken out of the sample bag, the excess solvent is wiped off, and the mass of the sample is weighed again m2; the swelling degree = (m2-m1) / m1x100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0226] It should be noted that the porous coating parameters of the above-mentioned separation membrane are the porous coating parameters of 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 meet the present disclosure, and it is considered to fall within the protection scope of the present disclosure.

[0227] The present disclosure also provides a preparation method of a separation membrane.

[0228] The preparation method of the separation membrane comprises the following steps: providing a porous base film; providing a slurry comprising organic particles, inorganic particles, and a binder; coating the slurry on at least one side of the porous base film, and drying to obtain the separation membrane.

[0229] 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 organic particles and the inorganic particles and form protrusions on the surface of the porous coating.

[0230] In some embodiments, the preparation method of the separation membrane can comprise the following steps: coating a heat-resistant layer slurry comprising organic particles, inorganic particles, and a binder on at least one side of the porous base film, and drying to form a heat-resistant layer; and coating an adhesive layer slurry comprising polymer binder particles and a binder on at least a part of the surface of the heat-resistant layer, and drying to obtain the separation membrane.

[0231] In some embodiments, the method for preparing the separation membrane can include: coating a heat-resistant slurry including organic particles, inorganic particles, and a binder on one side of a porous base membrane, and coating a bonding layer slurry including polymer binder particles and a binder on at least a portion of the surface of the other side of the porous base membrane, to obtain the separation membrane after drying.

[0232] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0233] In some embodiments, the slurry can further include other components, for example, can further include a dispersant and / or a wetting agent, etc.

[0234] In some embodiments, the organic particles are cross-linked styrene-based organic particles, and the method for preparing the organic particles can include the following steps: providing a pre-emulsion containing a first monomer, a first cross-linking agent, a first emulsifier, a first initiator, and water, the first monomer including one or more of styrene and derivatives thereof; and performing emulsion polymerization of the pre-emulsion under heating, inert gas protection, and stirring conditions to obtain the organic particles.

[0235] In some embodiments, the emulsion polymerization can include the following steps: under a first temperature, inert gas protection, and stirring conditions, dropping the pre-emulsion into a reactor containing water, and after a first time, increasing the temperature to a second temperature for a second time to obtain the cross-linked styrene-based organic particles.

[0236] In some embodiments, the first temperature can be 55°C-70°C.

[0237] In some embodiments, the first time can be 3h-6h.

[0238] In some embodiments, the second temperature can be 72°C-92°C, for example, can be 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, or a range consisting of any of the above values.

[0239] In some embodiments, the second time can be 1h-6h, for example, can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or a range consisting of any of the above values.

[0240] The emulsion polymerization is performed under inert gas protection. In some embodiments, the inert gas can include one or more of nitrogen, argon, and helium.

[0241] In some embodiments, the first monomer can include one or more of styrene, 1-methyl-1-styrene, 4-methylstyrene, 2-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene.

[0242] In some embodiments, the first crosslinking agent can include one or more of divinylbenzene, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropylene glycol diacrylate, N,N-methylenebisacrylamide, N,N'-vinylbisacrylamide, 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl isocyanurate.

[0243] In some embodiments, the mass fraction of the first crosslinking agent can be 5%-40%, for example, can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or a range consisting of any of the aforementioned values, based on the total mass of the first monomer and the first crosslinking agent being 100%.

[0244] The high content of the first crosslinking agent can make the obtained crosslinked styrene-based organic particles have better heat resistance.

[0245] Alternatively, the mass fraction of the first crosslinking agent can be 7%-40%, 9%-40%, 11%-40%, 13%-40%, 15%-40%, 7%-35%, 9%-35%, 11%-35%, 13%-35%, 15%-35%, 7%-31%, 9%-31%, 11%-31%, 13%-31%, 15%-31%.

[0246] In some embodiments, the first emulsifier can include one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, polyoxyethylene ether emulsifier.

[0247] Alternatively, the polyoxyethylene ether emulsifier can include OP-type emulsifiers, such as OP-4, OP-7, OP-10, OP-15, OP-20, etc.

[0248] In some embodiments, the mass fraction of the first emulsifier can be 0.25%-5%, based on 100% of the total mass of the first monomer and the first crosslinking agent.

[0249] In some embodiments, the first initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisdimethylamid hydrochloride, azobisdimethylimidazoline hydrochloride, and azobisisopropylimidazoline.

[0250] In some embodiments, the organic particles are silicon-containing organic crosslinked resin particles, and a method for preparing the organic particles can include the steps of: providing a pre-emulsion containing a second monomer, a second crosslinking agent, a second emulsifier, a second initiator, and water, the second monomer including a silane coupling agent containing an alkenyl group and / or an acryloyloxy group; and performing emulsion polymerization on the pre-emulsion under conditions of heating, inert gas protection, and stirring to obtain the organic particles.

[0251] The second monomer includes a silane coupling agent containing an alkenyl group and / or an acryloyloxy group, so that free radicals are generated between the second monomers to initiate crosslinking reactions, and the second monomers also undergo crosslinking reactions with the second crosslinking agent. Therefore, the silicon-containing organic crosslinked resin particles with a three-dimensional network molecular structure can be formed using the second monomer and the second crosslinking agent of the present disclosure, which are not easily softened or deformed at high temperatures and have high heat resistance.

[0252] In some embodiments, the emulsion polymerization includes the steps of: dropping the pre-emulsion into a reactor containing water under conditions of a third temperature, inert gas protection, and stirring, and then heating to a fourth temperature for a fourth time to obtain the silicon-containing organic crosslinked resin particles.

[0253] In some embodiments, the third temperature can be 55°C-70°C.

[0254] In some embodiments, the third time can be 3h-6h.

[0255] In some embodiments, the fourth temperature can be 72°C-92°C, for example, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, or a range formed by any of the above values.

[0256] In some embodiments, the fourth time can be 1 h-5 h, for example, can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h, 5 h, or a range consisting of any of the aforementioned values.

[0257] The emulsion polymerization reaction is carried out under inert gas protection. In some embodiments, the inert gas can include one or more of nitrogen, argon, and helium.

[0258] In some embodiments, the method can further include the step of drying the product obtained from the emulsion polymerization reaction, and then subjecting the product to a crushing process and a wet grinding process to obtain the silicon-containing organic crosslinked resin particles.

[0259] In other embodiments, the method can further include the step of drying the product obtained from the emulsion polymerization reaction, and then subjecting the product to baking under an inert gas atmosphere, and then subjecting the product to a crushing process and a wet grinding process to obtain the silicon-containing organic crosslinked resin particles. In this way, the silicon-containing organic crosslinked resin particles with better heat resistance can be obtained.

[0260] In some embodiments, the drying of the product obtained from the emulsion polymerization reaction can include, but is not limited to, vacuum drying, spray drying, air blowing drying, microwave drying, or fluidized bed drying.

[0261] In some embodiments, the drying of the product obtained from the emulsion polymerization reaction can be carried out at a temperature of 80°C-150°C, for example, can be 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 consisting of any of the aforementioned values.

[0262] In some embodiments, the drying of the product obtained from the emulsion polymerization reaction can be carried out for a time of 2 h-12 h, for example, can be 2 h, 2.4 h, 2.8 h, 3.2 h, 3.6 h, 4 h, 4.4 h, 4.8 h, 5.2 h, 5.6 h, 6 h, 6.4 h, 6.8 h, 7.2 h, 7.6 h, 8 h, 8.4 h, 8.8 h, 9.2 h, 9.6 h, 10 h, 10.4 h, 10.8 h, 11.2 h, 11.6 h, 12 h, or a range consisting of any of the aforementioned values.

[0263] The baking is carried out under an inert gas atmosphere. In some embodiments, the inert gas can include one or more of nitrogen, argon, and helium.

[0264] In some embodiments, the temperature of the baking can be 160-250℃, for example, can be 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, or a range consisting of any of the aforementioned values.

[0265] In some embodiments, the time of the baking can be 1-8h, 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 consisting of any of the aforementioned values. Alternatively, the time of the baking can be 2-8h, 2.4-8h, 3-8h.

[0266] 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.

[0267] In some embodiments, the wet grinding process can comprise 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 crosslinked resin particles.

[0268] Alternatively, the solvent can comprise one or more of water, methanol, ethanol. More alternatively, the solvent can comprise water.

[0269] Alternatively, the dispersant can comprise 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 comprise one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, ammonium acrylate. Alternatively, the carboxymethyl cellulose type dispersant can comprise one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose.

[0270] Alternatively, the grinding medium can comprise one or more of zirconium oxide balls, aluminum oxide balls, silicon nitride balls.

[0271] Alternatively, the average particle size of the grinding medium can be 0.1-2mm.

[0272] Alternatively, the rotation speed of the grinding can be 500-3000rpm.

[0273] In some embodiments, the second monomer can include a vinyl silane coupling agent and / or an acryloxy silane coupling agent.

[0274] Optionally, the second monomer can include 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-methacryloxypropyltri(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(beta-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.

[0275] In some embodiments, the second crosslinking agent can be a multifunctional crosslinking agent.

[0276] Optionally, the second crosslinking agent can include divinylbenzene.

[0277] Optionally, the second crosslinking agent can include divinylbenzene and one or more of divinyl 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 pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropyleneglycol 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.

[0278] In some embodiments, the mass fraction of the second 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 100% of the total mass of the second monomer and the second crosslinking agent.

[0279] The mass fraction of the second crosslinking agent in the above range can obtain a silicon-containing organic crosslinking resin particle with good heat resistance.

[0280] Optionally, the mass fraction of the second crosslinking agent can be 4%-18%, 6%-18%, 8%-18%, 4%-16%, 6%-16%, 8%-16%, 4%-15%, 6%-15%, 8%-15%.

[0281] In some embodiments, the second 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 second emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, lauryl alcohol polyether-7, lauryl alcohol polyether-9, lauryl alcohol polyether-10, oleyl alcohol polyether-10.

[0282] In some embodiments, the second initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobis isobutyl amide hydrochloride, azobis isobutyl imidazole hydrochloride, azobis isopropyl imidazole.

[0283] In some embodiments, the mass fraction of the second 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 aforementioned values, based on 100% of the total mass of the second monomer and the second crosslinking agent. Optionally, the mass fraction of the second initiator can be 0.3%-2.1%, 0.3%-1.9%, 0.3%-1.7%, 0.3%-1.5%, 0.3%-1.3%.

[0284] In some embodiments, the pre-emulsion can further include a pH adjuster. Optionally, the pH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia, etc.

[0285] In some embodiments, the organic particles are phenolic resin-based organic particles, and the method for preparing the organic particles can comprise the following steps: providing a resol phenolic resin-based material; curing the resol phenolic resin-based material at a fifth temperature under a first atmosphere for a fifth time, and then curing the resol phenolic resin-based material at a sixth temperature under a second atmosphere for a sixth time, and then crushing and wet sanding to obtain the organic particles, the fifth temperature being 90-180°C, and the sixth temperature being 190-290°C.

[0286] The fifth temperature can be 90-180°C, for example, 90°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 180°C, or a range formed by any two of the above values.

[0287] The fifth temperature in the above range can make the curing of the resol phenolic resin-based material in the fifth stage more uniform and sufficient, so that the phenolic resin-based organic particles with good heat resistance can be obtained.

[0288] Alternatively, the fifth temperature can be 90-180°C, 100-180°C, 110-180°C, 100-165°C, 110-165°C.

[0289] The fifth temperature in the above range can make the curing of the resol phenolic resin-based material in the fifth stage more uniform and sufficient, so that the phenolic resin-based organic particles with good heat resistance can be obtained.

[0290] The sixth temperature can be 190-290°C, for example, 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, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, or a range formed by any two of the above values.

[0291] The sixth temperature in the above range can make the curing of the phenolic resin-based organic particles more sufficient, so that the phenolic resin-based organic particles with good heat resistance can be obtained.

[0292] Alternatively, the sixth temperature can be 200-285°C, 200-280°C.

[0293] The sixth temperature in the above range can make the curing of the phenolic resin-based organic particles more sufficient, so that the phenolic resin-based organic particles with good heat resistance can be obtained.

[0294] In some embodiments, the fifth time can be 1 h-5 h, such as 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h, 5 h, or a range of any of the above values.

[0295] The fifth time in the above range can make the curing of the resol phenolic resin-based material in the fifth stage more uniform and sufficient, thereby obtaining a phenolic resin-based organic particle with better heat resistance.

[0296] In some embodiments, the sixth time can be 1 h-6 h, such as 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h, 5 h, 5.2 h, 5.4 h, 5.6 h, 5.8 h, 6 h, or a range of any of the above values.

[0297] The sixth time in the above range can make the curing of the phenolic resin-based organic particle more sufficient and have better heat resistance.

[0298] In some embodiments, the first atmosphere can be an inert gas atmosphere or an oxygen-containing atmosphere. The oxygen-containing atmosphere can include oxygen and an inert gas. Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere can be 5%-50%. Optionally, the inert gas can include, but is not limited to, one or more of nitrogen, argon, and helium.

[0299] Optionally, the first atmosphere is an oxygen-containing atmosphere, and the volume fraction of oxygen in the oxygen-containing atmosphere can be 10%-30%. More optionally, the first atmosphere can be an air atmosphere.

[0300] In some embodiments, the second atmosphere can be an inert gas atmosphere or an oxygen-containing atmosphere. The oxygen-containing atmosphere can include oxygen and an inert gas. Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere can be 5%-50%. Optionally, the inert gas can include, but is not limited to, one or more of nitrogen, argon, and helium.

[0301] Optionally, the second atmosphere is an oxygen-containing atmosphere, and the volume fraction of oxygen in the oxygen-containing atmosphere can be 10%-30%. More optionally, the second atmosphere can be an air atmosphere.

[0302] The resol phenolic resin-based material can be commercially available or synthesized according to methods known in the art. In some embodiments, the method for preparing the resol phenolic resin-based material includes the following steps: reacting a phenolic compound and an aldehyde compound under the catalysis of an alkaline substance to obtain the resol phenolic resin-based material.

[0303] Optionally, the basic substance can include one or more of ammonia, NaOH, Na2CO3.

[0304] Optionally, the phenolic compound can include one or more of phenol, hydroquinone, resorcinol, catechol, cresol, cardanol.

[0305] Optionally, the aldehyde compound can include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0306] In some embodiments, the organic particles are polymer particles containing triazine ring structure units, and the method for preparing the organic particles can include the following steps: providing a precursor containing a triazine ring structure; heating and curing the precursor containing the triazine ring structure in an oxygen-containing atmosphere, and then crushing and wet grinding to obtain the organic particles, and the heating and curing temperature is 180-290°C. After heating and curing of the precursor containing the triazine ring structure, a bridging structure is formed between the triazine ring structure units.

[0307] The heating and curing temperature is 180-290°C, for example, it can be 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, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, or a range consisting of any of the above values. The heating and curing temperature in the above range can obtain polymer particles containing triazine ring structure units with good heat resistance.

[0308] Optionally, the heating and curing temperature can be 200-285°C, 205-285°C, 215-285°C, 225-285°C.

[0309] In some embodiments, the heating and curing time can be 1-8h, for example, it can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h, 5h, 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 consisting of any of the above values. The heating and curing time in the above range is beneficial for the precursor containing the triazine ring structure to form polymer particles containing triazine ring structure units with better heat resistance.

[0310] Optionally, the time for heating and curing can be 2h-7h, 2.4h-7h, 2.8h-7h, 2h-6.6h, 2.4h-6.6h, 2.8h-6.6h.

[0311] In some embodiments, the oxygen-containing atmosphere can include oxygen and an inert gas. Optionally, the inert gas can include, but is not limited to, one or more of nitrogen, argon, helium. In some embodiments, the volume fraction of oxygen in the oxygen-containing atmosphere can be 5%-50%. Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere can be 10%-30%. More optionally, the oxygen-containing atmosphere can be an air atmosphere.

[0312] In some embodiments, the precursor containing a triazine ring structure can include at least one of a melamine-formaldehyde resin, an etherified melamine-formaldehyde resin, a mixture of the etherified melamine-formaldehyde resin and at least one of a polyol, a polycarboxylic acid, a polyamide.

[0313] In some embodiments, the precursor containing a triazine ring structure can include a melamine-formaldehyde resin, which can be obtained by reacting an aldehyde compound and an amine-substituted triazine compound, the amine-substituted triazine compound can include melamine and / or melamine derivatives. Optionally, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 1.75:1-3:1, for example, can be 1.75:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, or a range consisting of any of the foregoing. More optionally, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 2:1-3:1, 2.1:1-3:1, 2.2:1-3:1, 2.3:1-3:1, 2.4:1-3:1.

[0314] In some embodiments, the precursor containing a triazine ring structure can include an etherified melamine-formaldehyde resin, which can be obtained by reacting an aldehyde compound, an amine-substituted triazine compound, and an alcohol compound, the amine-substituted triazine compound can include melamine and / or melamine derivatives. Optionally, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 4:1-7:1, for example, can be 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, or a range consisting of any of the foregoing. More optionally, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 5:1-7:1, 5.5:1-7:1, 6:1-7:1, 6.5:1-7:1.

[0315] In some embodiments, the precursor containing triazine ring structure includes a mixture of etherified melamine formaldehyde resin and a polyol, and the molar ratio of etherified melamine formaldehyde resin to polyol can be 1 :2-1 :6.

[0316] In some embodiments, the precursor containing triazine ring structure includes a mixture of etherified melamine formaldehyde resin and a polyol, and the molar ratio of etherified melamine formaldehyde resin to polyol can be 1 :2-1 :6.

[0317] In some embodiments, the precursor containing triazine ring structure includes a mixture of etherified melamine formaldehyde resin and a polyol, and the molar ratio of etherified melamine formaldehyde resin to polyol can be 1 :2-1 :6.

[0318] In some embodiments, the alcohol compound forming the etherified melamine formaldehyde resin can include one or more of methanol, ethanol, and butanol.

[0319] In some embodiments, the aldehyde compound forming the melamine formaldehyde resin and the etherified melamine formaldehyde resin can include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0320] In some embodiments, the amine-substituted triazine compound forming the melamine formaldehyde resin and the etherified melamine formaldehyde resin can include one or more of the following general compounds, R1, R2are each independently selected from any one of H, -NH2, C1-C8 alkyl, R3is selected from any one of H, -NH2, -NHR4, C1-C8 alkyl, C2-C8 alkenyl, phenyl, C7-C12 alkylphenyl, C7-C12 phenylalkyl, C5-C8 cycloalkyl, and R4is selected from any one of -NH2, C1-C8 alkyl. Alternatively, R3is selected from -NH2or -NHR4.

[0321] Optionally, the amine-substituted triazine compound can include one or more of melamine, benzoguanamine, 2,4-diamino-1,3,5-triazine, 6-methyl-1,3,5-triazine-2,4-diamine, 2,4,6-triethylamino-1,3,5-triazine, trihydrazinotriazine, 2-amino-4-methylamino-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 6-ethyl-1,3,5-triazine-2,4-diamine, 6-isopropyl-1,3,5-triazine-2,4-diamine, 6-pentyl-2,4-diamino-1,3,5-triazine, 6-heptyl-2,4-diamino-triazine, 2-vinyl-4,6-diamino-1,3,5-triazine, 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine, 6-cyclohexyl-1,3,5-triazine-2,4-diamine, 6-(3-methylphenyl)-1,3,5-triazine-2,4-diamine, 6-o-tolyl-1,3,5-triazine-2,4-diamine, 6-(2,4-dimethylphenyl)-1,3,5-triazine-2,4-diamine, 6-phenylmethyl-1,3,5-triazine-2,4-diamine, (diamino-1,3,5-triazin-2-yl)methanol, 2-chloro-4,6-diamino-1,3,5-triazine.

[0322] More optionally, the amine-substituted triazine compound can include one or more of melamine, benzoguanamine, 2,4-diamino-1,3,5-triazine, 6-methyl-1,3,5-triazine-2,4-diamine, 2,4,6-triethylamino-1,3,5-triazine, trihydrazinotriazine, 2-amino-4-methylamino-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine.

[0323] The etherified melamine aldehyde resin can include one or more of a partially etherified melamine aldehyde resin, a fully etherified melamine aldehyde resin. Optionally, the etherified melamine aldehyde resin can include a fully etherified melamine aldehyde resin.

[0324] In some embodiments, the etherified melamine aldehyde resin can include one or more of a methyl etherified melamine aldehyde resin, an ethyl etherified melamine aldehyde resin, a butyl etherified melamine aldehyde resin, a methyl butyl mixed etherified melamine aldehyde resin.

[0325] Optionally, the etherified melamine aldehyde resin can include one or more of a methyl etherified melamine formaldehyde resin, a butyl etherified melamine formaldehyde resin, a methyl etherified benzoguanamine formaldehyde resin, a butyl etherified benzoguanamine formaldehyde resin.

[0326] The embodiments of the present disclosure also provide a secondary battery cell. The secondary battery cell comprises 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 energy density and high reliability.

[0327] The secondary battery cell also comprises a positive electrode tab, a negative electrode tab and an electrolyte, and the separator film is arranged 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.

[0328] The secondary battery cell provided by the present disclosure can include, but is not limited to, a lithium battery cell, a sodium battery cell, etc., and the composition of the positive electrode tab, the negative electrode tab and the electrolyte will be different for different types of secondary battery cells.

[0329] [Positive electrode tab]

[0330] In some embodiments, the positive electrode tab can include a positive current collector and a positive film layer arranged on at least one surface of the positive current collector and comprising a positive active material. For example, the positive current collector has two surfaces opposite in the thickness direction of itself, and the positive film layer is arranged on any one or both of the two opposite surfaces of the positive current collector.

[0331] Taking a lithium battery cell as an example, the positive active material can include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates and their respective modified compounds. Examples of lithium transition metal oxides can include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides and their respective modified compounds. Examples of lithium-containing phosphates can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon and their respective modified compounds. In some embodiments, in order to further improve the energy density of the secondary battery cell, the positive active material can include one or more of lithium transition metal oxides with a general formula of Li a Ni b Co c M d O e A f , 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.

[0332] As an example, the positive active material can include, but is not limited to, one or more of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.1 Al 0.05 O2, LiFePO4, LiMnPO4.

[0333] 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 enumeration of the positive active material in the present disclosure, the molar content of Li is the initial state of the material, i.e. the state before feeding, and the positive active material is applied to the secondary battery cell. After charging and discharging cycle, the molar content of Li will change. In the enumeration of the positive active material in the present disclosure, the molar content of O 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.

[0334] Taking a sodium battery cell as an example, the positive 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 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 the general formula is X p M’ q (PO4) r O x Y3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In this case, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes, but is not limited to, H. + Li + Na + K + and NH4 + One or more of the following, M' is a transition metal cation, optionally including but not limited to one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally one or more of F, Cl and Br.

[0335] The modified compounds for the positive electrode active materials of the aforementioned lithium battery cells and sodium battery cells can be obtained by doping and / or surface coating modifications of the positive electrode active materials.

[0336] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0337] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0338] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0339] 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.

[0340] [Anode electrode sheet]

[0341] In some embodiments, the anode electrode sheet can include an anode current collector and an anode film layer disposed on at least one surface of the anode current collector and including an anode active material. For example, the anode current collector has two surfaces opposite in the thickness direction of itself, and the anode film layer is disposed on any one or both of the two opposite surfaces of the anode current collector.

[0342] The anode active material can employ a material known in the art that can be used for a secondary battery cell. As an example, the anode active material can include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, 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 silicon alloy material. The tin-based material can include, but is not limited to, one or more of elemental tin, tin oxide, and tin alloy material.

[0343] In some embodiments, the anode film layer can further include an anode conductive agent. As an example, the anode 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.

[0344] In some embodiments, the anode film layer can further include an anode binder. As an example, the anode 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).

[0345] In some embodiments, the anode 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.

[0346] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0347] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0348] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0349] In some embodiments, the negative electrode sheet can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0350] [Electrolytes]

[0351] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0352] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0353] Taking a lithium battery cell as an example, the electrolyte salt may include, but is not limited to, one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0354] For example, 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 difluoro oxalato borate (NaDFOB), sodium bisoxalato borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluoro di-oxalato phosphate (NaDFOP), and sodium tetrafluoro oxalato phosphate (NaTFOP).

[0355] 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.

[0356] In some embodiments, an additive can also be included in the electrolyte. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and / or an additive that can improve certain properties of the secondary battery cell, such as an additive that improves overcharge performance, an additive that improves high-temperature performance, an additive that improves low-temperature performance, and / or the like.

[0357] Optionally, the additive can include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), and / or vinyl sulfate (DTD).

[0358] Methods of making secondary battery cells are 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 via a winding process and / or a stacking process, the electrode assembly can be placed in an outer package, the electrode assembly can be dried and then injected with an electrolyte, and the secondary battery cell can be subjected to a resting process, a formation process, and / or the like.

[0359] Embodiments

[0360] The present disclosure is described in more detail by the following examples, which are merely illustrative and not limiting, as various modifications and changes in the examples clearly will occur to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further purification, and the instruments used in the examples are commercially available.

[0361] Example 1

[0362] Preparation of the separator film

[0363] A pre-emulsion was prepared by emulsifying 0.8 g of sodium dodecyl sulfate, 80 mg of sodium persulfate, 20 ml of deionized water, 34 g of styrene, and 6 g of divinylbenzene. 140 g of deionized water and 15 mg of sodium polyacrylate were added to a reactor, 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 85°C for 1.5 h of curing reaction to obtain a cross-linked styrene-based organic particle emulsion.

[0364] The above emulsion, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate were stirred uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the cross-linked styrene-based organic particles, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the heat-resistant layer slurry was 80:10:2:8.

[0365] Commercially available polyvinylidene fluoride particles, binder polymethyl methacrylate, dispersant sodium carboxymethyl cellulose, and ether-based surfactant were stirred uniformly in deionized water at a solid mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0366] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure coating, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. After drying and slitting, the separator film was obtained.

[0367] Preparation of the secondary battery cell

[0368] The positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O2, and the positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97:2:1 in N-methyl pyrrolidone (NMP) to prepare a positive electrode slurry. The positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slitted to obtain a positive electrode sheet.

[0369] The negative active material artificial graphite, the negative conductive agent acetylene black, the negative binder styrene-butadiene rubber (SBR), and the thickening agent sodium carboxymethyl cellulose are added into deionized water according to a mass ratio of 96.0:1.5:1.5:1, and a negative slurry is prepared after being fully stirred and mixed uniformly; the negative slurry is uniformly coated on the negative current collector copper foil, and then dried, cold-pressed, and cut to obtain a negative electrode sheet.

[0370] At 25°C, ethylene carbonate (EC) and methyl ethyl carbonate (EMC) are mixed according to a volume ratio of 3:7 to obtain a mixed solvent, and then LiPF6, vinylene carbonate (VC), and vinyl sulfate (DTD) are dissolved in the mixed solvent to obtain an electrolyte. The concentration of LiPF6 is 1 mol / L. The mass fraction of VC is 2%, and the mass fraction of DTD is 3%, based on the mass of the electrolyte.

[0371] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence and wound and hot-pressed to obtain an electrode assembly; the electrode assembly is placed in an aluminum-plastic film outer package, and the electrolyte prepared above is added, and after processes such as packaging, standing, formation, and aging, a secondary battery monomer is obtained.

[0372] Example 2

[0373] The preparation of the secondary battery monomer is the same as that in Example 1, except for the following differences.

[0374] Preparation of the separator

[0375] The solid mass ratio of the cross-linked styrene-based organic particles, aluminum oxide, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the heat-resistant layer slurry is 70:20:2:8.

[0376] Example 3

[0377] The preparation of the secondary battery monomer is the same as that in Example 1, except for the following differences.

[0378] Preparation of the separator

[0379] The solid mass ratio of the cross-linked styrene-based organic particles, aluminum oxide, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the heat-resistant layer slurry is 50:40:2:8.

[0380] Example 4

[0381] The preparation of the secondary battery monomer is the same as that in Example 1, except for the following differences.

[0382] Preparation of the separator

[0383] 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 triisopropoxy silane, 3 g of 3-methacryloxypropyl triethoxy silane, and 5 g of divinyl benzene. 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 the dropwise addition was completed, the reaction was continued for 4 h, and then the temperature was raised to 84°C for 1.5 h of curing reaction, to obtain a silicon-containing organic crosslinking resin particle emulsion.

[0384] The above emulsion, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate were stirred uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the silicon-containing organic crosslinking resin particles, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the heat-resistant layer slurry was 50:40:2:8.

[0385] Commercially available polyvinylidene fluoride particles, binder polymethyl methacrylate, dispersant sodium carboxymethyl cellulose, and ether-based surfactant were stirred uniformly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0386] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure coating, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. After drying and slitting, a separator film was obtained.

[0387] Example 5

[0388] The preparation of the secondary battery cell was the same as in Example 1, except for the following differences.

[0389] Preparation of a separator film

[0390] A commercially available phenol and formaldehyde-based resol resin material was placed in a curing oven, the atmosphere was set to air, the temperature was set to 135°C, and the temperature was maintained for 3 h of curing. After the curing was completed, the temperature of the curing oven was raised to 255°C, and the temperature was maintained for 3 h of curing. After the two curing processes were completed, the cured resol resin material was taken out, naturally cooled in air, and then crushed, wet ground, and wet demagnetized to obtain a resol resin organic particle slurry.

[0391] The above slurry, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate were stirred uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the resol resin organic particles, alumina, dispersant sodium carboxymethyl cellulose, and binder polymethyl methacrylate in the heat-resistant layer slurry was 50:40:2:8.

[0392] The commercially available polyvinylidene fluoride particles, the binder polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose and the ether-based surfactant were uniformly stirred in deionized water at a solid content mass ratio of 87:8:3:2 to obtain the adhesive layer slurry.

[0393] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure method, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. Then, through drying and slitting processes, the separator film was obtained.

[0394] Example 6

[0395] The preparation of the secondary battery cell was the same as that of Example 1, except for the following differences.

[0396] Preparation of the separator film

[0397] A commercially available 37% formaldehyde aqueous solution was added to a container, and the pH value was adjusted to 9.0-9.2 with a sodium hydroxide aqueous solution. The mixed solution with the adjusted pH value was added to a reaction container, heated to 50°C under stirring, and then melamine was added to the reaction container. The molar ratio of formaldehyde to melamine was 2.5:1. The reaction temperature was raised to 85°C, and the reaction was carried out for 9-10 h to obtain a liquid melamine formaldehyde resol precursor. The liquid melamine formaldehyde resol precursor was placed in a drying oven and cured at 200°C in an air atmosphere for 6 h after the water turbidity of the material was tested to 1:3. Then, after crushing and wet grinding with water, a slurry of polymer particles containing triazine ring structural units was obtained.

[0398] The above slurry, aluminum oxide, dispersant sodium carboxymethyl cellulose and binder polymethyl methacrylate were uniformly stirred in deionized water to obtain the heat-resistant layer slurry. The solid mass ratio of the polymer particles containing triazine ring structural units, aluminum oxide, dispersant sodium carboxymethyl cellulose and binder polymethyl methacrylate in the heat-resistant layer slurry was 50:40:2:8.

[0399] The commercially available polyvinylidene fluoride particles, the binder polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose and the ether-based surfactant were uniformly stirred in deionized water at a solid content mass ratio of 87:8:3:2 to obtain the adhesive layer slurry.

[0400] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure method, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. Then, through drying and slitting processes, the separator film was obtained.

[0401] Comparative Example 1

[0402] The preparation of the secondary battery cell was the same as that of Example 1, except for the following differences.

[0403] Preparation of the isolation film

[0404] A pre-emulsion was prepared by emulsifying 0.8 g of sodium dodecyl sulfate, 80 mg of sodium persulfate, 20 ml of deionized water, 39.6 g of styrene, and 0.4 g of divinylbenzene. 140 g of deionized water and 15 mg of sodium polyacrylate were added to a reactor, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring, and the reaction was carried out for 4 h. The temperature was then raised to 85°C for 1.5 h to complete the reaction, and a cross-linked styrene-based organic particle emulsion was obtained.

[0405] The cross-linked styrene-based organic particle emulsion, the dispersant sodium carboxymethyl cellulose, and the binder polymethyl methacrylate were stirred and mixed uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the cross-linked styrene-based organic particles, the dispersant sodium carboxymethyl cellulose, and the binder polymethyl methacrylate in the heat-resistant layer slurry was 90:2:8.

[0406] The commercially available polyvinylidene fluoride particles, the binder polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose, and the ether-based surfactant were stirred and mixed uniformly in deionized water at a solid mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0407] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by micro-gravure method, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. After drying and slitting, the isolation film was obtained.

[0408] Performance test

[0409] (1) Heat shrinkage rate test of the isolation film

[0410] The heat shrinkage rate test of the isolation film can refer to GB / T 36363-2018.

[0411] The isolation film was cut into samples with a width of 50 mm and a length of 100 mm by a punch machine. Five parallel samples were placed on an A4 paper, and the A4 paper with the samples was placed on corrugated paper with a thickness of 1 mm to 5 mm.

[0412] The temperature of the air-blast oven was set to 140°C. 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 started. After reaching the set time (1 h in the present disclosure), the length and width of the isolation film were measured, and the values were marked as a and b, respectively.

[0413] Thermal shrinkage calculation: longitudinal (MD) thermal shrinkage = [(100-a) / 100] x 100%, transverse (TD) thermal shrinkage = [(50-b) / 50] x 100%, and the average value of 3 parallel samples was taken as the test result.

[0414] (2) Hot box test

[0415] The secondary battery monomer was charged at 25℃ with 1C constant current to 4.35V, and then charged with 4.35V constant voltage to 0.05C current, and then rested for 5min, and then each secondary battery monomer was tested in a DHG-9070A DHG series high temperature oven with a clamp, and the temperature was raised from room temperature to 60℃ at a rate of 5℃ / min, and maintained for 5h; and then the temperature was raised at a rate of 5℃ / min, and every 5℃ rise, the temperature was maintained for 30min, until the secondary battery monomer failed, and the hot box temperature at which the secondary battery monomer failed was recorded.

[0416] Table 1

[0417] From the above test results, it can be seen that the isolation film of the present disclosure has good heat resistance, and can improve the thermal safety of the secondary battery monomer.

[0418] 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 solutions of the present disclosure are all included within 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 are applied to the embodiments, and other ways constructed by combining part of the constituent elements in the embodiments are also included within the scope of the present disclosure.

Claims

1. An isolation membrane comprising a porous base film and a porous coating layer on at least one side of the porous base film, wherein, The porous coating comprises organic particles and inorganic particles, and the mass proportion of the organic particles in the porous coating is greater than the mass proportion of the inorganic particles in the porous coating.

2. The separator film according to claim 1, wherein The mass proportion of the organic particles in the porous coating is 50%-93%; and / or, the mass proportion of the inorganic particles in the porous coating is 5%-45%.

3. The separator film according to claim 2, wherein The mass proportion of the organic particles in the porous coating is 60%-88%; and / or, the mass proportion of the inorganic particles in the porous coating is 10%-30%.

4. The separator film according to any one of claims 1 to 3, wherein The cyclic voltammogram of the organic particles in the first cycle has no oxidation peak in the voltage range of 2.5V to 4.4V.

5. The separator film according to any one of claims 1 to 4, wherein The organic particles satisfy one or more of the following conditions (1) to (4): (1) The swelling degree of the organic particles immersed in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60℃ for 7 days is less than or equal to 3%; (2) The dissolution rate of the organic particles immersed in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60℃ for 7 days is less than or equal to 3%; (3) The organic particles have no melting point; (4) the initial thermal weight loss temperature T of the organic particles is greater than or equal to 240°C. 3d greater than or equal to 240°C.

6. The separator film according to any one of claims 1-5, wherein, The true density of the organic particles is 1.0 g / cm 3 - 2.0 g / cm 3 ; and / or, The inorganic particles have a true density of 2.5 g / cm 3 - 3.5 g / cm 3 .

7. The separator film according to any one of claims 1 to 6, wherein The organic particles comprise at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a cross-linked polymer; Optionally, the thermoplastic resin polymer comprises one or more of polycarbonate organic particles, polymethyl acrylate methyl ester organic particles, polyformaldehyde organic particles, polyamide organic particles, styrene-acrylonitrile copolymer, polyphenylene sulfide organic particles, polyether ether ketone organic particles, polyimide organic particles, polysulfone organic particles, polyether sulfone organic particles, polyphenylene sulfone organic particles, polybenzimidazole organic particles, polyamide-imide organic particles, and polyethylene imine organic particles. Optionally, the thermosetting resin polymer comprises one or more of phenolic resin organic particles, polymer particles containing triazine ring structural units, epoxy resin organic particles, unsaturated polyester resin organic particles, urea-formaldehyde resin organic particles, and furan resin organic particles. Optionally, the cross-linked polymer comprises one or more of cross-linked styrene organic particles and silicon-containing organic cross-linked resin particles.

8. The separator film according to any one of claims 1-7, wherein, The organic particles comprise at least one of a thermosetting resin polymer or a cross-linked polymer; Optionally, the organic particles comprise one or more of cross-linked styrene organic particles, silicon-containing organic cross-linked resin particles, phenolic resin organic particles, and polymer particles containing triazine ring structural units.

9. The separator film according to any one of claims 1 to 8, wherein The organic particles comprise cross-linked styrene organic particles, and the cross-linked styrene organic particles comprise styrene or styrene derivative structural units and cross-linking structural units; Optionally, the styrene or styrene derivative structural unit includes one or more of a styrene structural unit, a 1-methyl-1-styrene structural unit, a 4-methylstyrene structural unit, a 2-methylstyrene structural unit, a 2,4-dimethylstyrene structural unit, a 2,5-dimethylstyrene structural unit. Optionally, the crosslinking structural unit includes one or more of a divinylbenzene structural unit, an ethylene glycol dimethacrylate structural unit, a pentaerythritol tetraacrylate 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, an N,N-methylenebisacrylamide structural unit, an N,N'-vinylbisacrylamide structural unit, a 1,3,5-triacryloylhexahydro-1,3,5-triazine structural unit, a trisallylisocyanurate structural unit.

10. The separator membrane according to any one of claims 1 to 9, wherein, The organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles satisfy one or more of the following conditions (1) to (3): (1) the crosslinked styrenic organic particles have a glass transition temperature Tg g of 110°C to 165°C; (2) the crosslinked styrenic organic particles have an onset thermal weight loss temperature T 3d of 335 °C - 388 °C; (3) The volume distribution particle diameter Dv50 of the crosslinked styrene-based organic particles is 80 nm to 300 nm.

11. The separator film according to any one of claims 1 to 10, wherein The organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles satisfy one or more of the following conditions (1) to (4): (1) The silicon-containing organic crosslinked resin particles contain a benzene ring structure; (2) The volume distribution particle diameter Dv50 of the silicon-containing organic crosslinked resin particles is 80 nm to 800 nm; (3) The silicon-containing organic crosslinked resin particles have no glass transition temperature below 300°C; (4) The initial thermogravimetric temperature T of the silicon-containing organic crosslinked resin particles 3d The temperature range is 240℃-330℃.

12. The separator film according to claim 11, wherein The silicon-containing organic crosslinked resin particles are network structures formed with carbon-carbon bonds as a main chain, and the side chains contain a siloxane structure and a benzene ring structure.

13. The separator membrane according to any one of claims 1 to 12, wherein, The organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles include a crosslinking structural unit, and the crosslinking structural unit includes a divinylbenzene structural unit.

14. The separator film according to claim 13, wherein The crosslinking structural unit further includes one or more of a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a maleic acid diallyl ester structural unit, a 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-trimethyl adipic acid bis[2-ethylaziridine] structural unit, a 1,1-sebacic acid bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylene dicarbonyl) 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.

15. The separator membrane according to any one of claims 1 to 14, wherein, The organic particles include phenol resin-based organic particles, and the phenol resin-based organic particles satisfy one or more of the following conditions (1) to (4): (1) The phenol resin-based organic particles are thermosetting resol; (2) The phenol resin-based organic particles have no glass transition temperature at 300°C or lower; (3) the initial thermal weight loss temperature T of the phenolic resin-based organic particles is 300°C to 350°C 3d is 300°C to 350°C; (4) The phenol resin-based organic particles have a volume distribution particle size Dv50 of 160 nm to 800 nm.

16. The separator membrane according to any one of claims 1 to 15, wherein, The organic particles include polymer particles containing a triazine ring structural unit, and the polymer particles containing a triazine ring structural unit satisfy one or more of the following conditions (1) to (4): (1) The polymer particles containing a triazine ring structural unit include a bridging structure connecting the triazine ring structural units; (2) The polymer particles containing a triazine ring structural unit have no glass transition temperature at 300°C or lower; (3) the initial thermal weight loss temperature T of the polymer particles containing the triazine ring structural unit is 3d 290°C to 340°C; (4) The polymer particles containing a triazine ring structural unit have a volume distribution particle size Dv50 of 160 nm to 800 nm.

17. The separator film according to claim 16, wherein The bridging structure includes one or a combination of two or more of an alkylene group, an alkylene ether group, an alkylene amine group, an ester group, and an amide group.

18. The separator membrane according to any one of claims 16-17, wherein, The polymer particles containing a triazine ring structural unit further have a substituent on the triazine ring structural unit, and the substituent includes one or a combination of two or more of an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an amine group, a hydroxyl group, and a halogen.

19. The separator membrane according to any one of claims 16-18, wherein, The polymer particles containing a triazine ring structural unit include at least one of a melamine formaldehyde-based polymer and a derivative thereof, an etherified melamine formaldehyde-based polymer and a derivative thereof, an etherified melamine formaldehyde-polyol polymer and a derivative thereof, an etherified melamine formaldehyde-polycarboxylic acid polymer and a derivative thereof, and an etherified melamine formaldehyde-polyamine amide polymer and a derivative thereof.

20. The separator film according to claim 19, wherein, the melamine-aldehyde polymer and derivatives thereof include one or more of melamine formaldehyde, benzoguanamine formaldehyde, melamine-benzoguanamine formaldehyde, melamine-(2,4-diamino-1,3,5-triazine) formaldehyde, melamine-(6-methyl-1,3,5-triazine-2,4-diamine) formaldehyde, melamine-(2,4,6-triethylamino-1,3,5-triazine) formaldehyde, trihydrazinotriazine formaldehyde, melamine-(2-amino-4-methylamino-1,3,5-triazine) formaldehyde, melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde; and / or, the etherified melamine-aldehyde polymer and derivatives thereof include one or more of methyl etherified melamine formaldehyde, butyl etherified melamine formaldehyde, methyl etherified benzoguanamine formaldehyde, butyl etherified benzoguanamine formaldehyde; and / or, the etherified melamine-aldehyde-polyol polymer and derivatives thereof include one or more of methyl etherified melamine formaldehyde-ethylene glycol polymer, methyl etherified melamine formaldehyde-1,2-propanediol polymer, methyl etherified melamine formaldehyde-1,4-butanediol polymer, methyl etherified melamine formaldehyde-polyester polyol polymer, methyl etherified melamine formaldehyde-polyvinyl alcohol polymer, butyl etherified melamine formaldehyde-ethylene glycol polymer, butyl etherified melamine formaldehyde-1,2-propanediol polymer, butyl etherified melamine formaldehyde-1,4-butanediol polymer, butyl etherified melamine formaldehyde-polyester polyol polymer; and / or, the etherified melamine-aldehyde-polycarboxylic acid polymer and derivatives thereof include one or more of methyl etherified melamine formaldehyde-oxalic acid polymer, methyl etherified melamine formaldehyde-malic acid polymer, methyl etherified melamine formaldehyde-succinic acid polymer, methyl etherified melamine formaldehyde-citric acid polymer, methyl etherified melamine formaldehyde-terephthalic acid polymer, methyl etherified melamine formaldehyde-phthalic acid polymer, butyl etherified melamine formaldehyde-oxalic acid polymer, butyl etherified melamine formaldehyde-malic acid polymer, butyl etherified melamine formaldehyde-citric acid polymer, butyl etherified melamine formaldehyde-terephthalic acid polymer, butyl etherified melamine formaldehyde-phthalic acid polymer; and / or, the etherified melamine-aldehyde-polyamine amide polymer and derivatives thereof include one or more of methyl etherified melamine formaldehyde-oxamide polymer, methyl etherified melamine formaldehyde-malonamide polymer, methyl etherified melamine formaldehyde-isophthalimide polymer, butyl etherified melamine formaldehyde-oxamide polymer.

21. The separator film according to any one of claims 1 to 20, wherein the volume distribution particle size Dv50 of the inorganic particles is 200 nm to 800 nm; and / or the inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, or inorganic particles capable of electrochemical reaction.

22. The separator film according to any one of claims 1 to 21, wherein the porous coating further comprises a binder; and / or, the porous coating has a thickness of 0.5-5 μm.

23. A method for preparing the separator film according to any one of claims 1-22, comprising the steps of: providing a porous base film; providing a slurry comprising organic particles, inorganic particles, and a binder; coating the slurry on at least one side of the porous base film to obtain the separator film after drying.

24. A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator film according to any one of claims 1-22, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

25. A battery device comprising a plurality of the secondary battery cell according to claim 24.

26. An electrically powered device comprising the secondary battery cell according to claim 24 or the battery device according to claim 25.

Images