Separator, secondary battery cell, battery device, and electric device

Abstract

Provided are a separator, 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, and the porous coating comprises heat-resistant organic particles and non-fluorinated polymer binder particles. The use of the separator in the secondary battery cell can enable the secondary battery cell to have high mass energy density, high reliability, and good cycle performance.

Description

Separator, secondary battery cell, battery device, and power consuming device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411388423.5, filed on September 30, 2024, entitled “Separator, secondary battery cell, battery device, and power consuming device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a separator, a secondary battery cell, a battery device, and a power consuming device. BACKGROUND

[0004] The separator is an important component for supporting the secondary battery cell to complete the charge-discharge electrochemical process. The commonly used separator is usually made of polyolefin material. However, the glass transition temperature of this kind of material is low, and serious thermal shrinkage will occur after heating. In order to improve the heat resistance of the separator, boehmite or alumina is commonly used as a heat-resistant filler and a binder to form a porous coating. The density of boehmite and alumina is relatively large, and the mass of boehmite and alumina is greater than that of other materials under the same bulk volume, which affects the energy density of the secondary battery cell. SUMMARY

[0005] The present disclosure provides a separator, a secondary battery cell, a battery device, and a power consuming device. The separator is used in the secondary battery cell, and the secondary battery cell has high mass energy density, high reliability, and good cycle performance.

[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, wherein the porous coating layer comprises heat-resistant organic particles and non-fluoropolymer binder particles.

[0007] By locating the heat-resistant organic particles on the porous base film, when the porous base film is transformed from a glassy state to a high-elastic state, the porous coating layer is still stable. The heat-resistant organic particles in the porous coating layer can generate a force to resist the shrinkage of the porous base film, thereby improving the overall thermal shrinkage of the separator, improving the heat resistance of the separator, and improving the reliability of the secondary battery cell. In addition, the true density of the heat-resistant organic particles is usually small, so that the secondary battery cell using the separator of the present disclosure has higher mass energy density. At the same time, the porous coating layer of the separator comprises non-fluoropolymer binder particles, which can further improve the adhesion between the separator and the electrode sheet. Therefore, the separator of the present disclosure can be closely bonded with the electrode sheet, improve the hardness of the electrode assembly, and improve the cycle performance of the secondary battery cell. Therefore, the separator of the present disclosure is used in the secondary battery cell, and the secondary battery cell has high mass energy density, high reliability, and good cycle performance.

[0008] In some embodiments, the non-fluoropolymer binder particles are embedded in the heat-resistant organic particles and form protrusions on the surface of the porous coating.

[0009] Optionally, the mass content of the heat-resistant organic particles in the porous coating is 68-92%.

[0010] Optionally, the mass content of the non-fluoropolymer binder particles in the porous coating is 5-30%.

[0011] Optionally, the porous coating further comprises fluoropolymer binder particles.

[0012] Optionally, the mass content of the non-fluoropolymer binder particles in the porous coating is greater than the mass content of the fluoropolymer binder particles in the porous coating.

[0013] Optionally, the particle size of the fluoropolymer binder particles is greater than the particle size of the non-fluoropolymer binder particles.

[0014] Optionally, the fluoropolymer binder particles comprise aggregates of primary particles.

[0015] In some embodiments, the porous coating comprises a heat-resistant layer and a bonding layer, the bonding layer is disposed on at least a portion of the surface of the heat-resistant layer or the porous base film, the heat-resistant organic particles are disposed in the heat-resistant layer, and the non-fluoropolymer binder particles are disposed in the bonding layer.

[0016] In some embodiments, the mass content of the heat-resistant organic particles in the heat-resistant layer is 50-99%.

[0017] In some embodiments, the mass content of the non-fluoropolymer binder particles in the bonding layer is 35-95%.

[0018] In some embodiments, the bonding layer further comprises fluoropolymer binder particles.

[0019] Optionally, the mass content of the non-fluoropolymer binder particles in the bonding layer is greater than the mass content of the fluoropolymer binder particles in the bonding layer.

[0020] Optionally, the particle size of the fluoropolymer binder particles is greater than the particle size of the non-fluoropolymer binder particles.

[0021] Optionally, the fluoropolymer binder particles comprise aggregates of primary particles.

[0022] In some embodiments, the heat-resistant organic particles include at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a cross-linked polymer.

[0023] In some embodiments, the thermoplastic resin polymer includes one or more of a polyphenylene sulfide-based organic particle, a polyimide-based organic particle, a polysulfone-based organic particle, a polyether sulfone-based organic particle, a polyphenylene sulfone-based organic particle, a polybenzimidazole-based organic particle, a polyamide-imide-based organic particle, a polyethylene imine-based organic particle, a polyether ether ketone-based organic particle.

[0024] In some embodiments, the thermosetting resin polymer includes one or more of a phenol formaldehyde resin-based organic particle, a polymer particle containing a triazine ring structure unit, an epoxy resin-based organic particle, an unsaturated polyester resin-based organic particle, a urea-formaldehyde resin-based organic particle, a furan resin-based organic particle.

[0025] In some embodiments, the cross-linked polymer includes one or more of a cross-linked styrene-based organic particle, a silicon-containing organic cross-linked resin particle.

[0026] In some embodiments, the heat-resistant organic particles have a true density of 1.0 g / cm 3 -2.0 g / cm 3 .

[0027] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the cyclic voltammetry curve of the heat-resistant organic particles in the first cycle has no oxidation peak in a voltage range of 2.5 V to 4.4 V. The cyclic voltammetry curve of the heat-resistant organic particles in the first cycle has no oxidation peak in a voltage window range of greater than or equal to 2.5 V and less than 4.4 V, indicating that the heat-resistant organic particles are stable in the voltage window range of greater than or equal to 2.5 V and less than 4.4 V and do not undergo electrochemical oxidation-reduction reactions, thereby enabling the secondary battery cell provided by the embodiments of the present disclosure to have a high voltage platform and a high quality energy density.

[0028] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the heat-resistant organic particles have an initial thermal weight loss temperature T 3d greater than or equal to 240℃. The heat-resistant organic particles have an initial thermal weight loss temperature T 3d greater than or equal to 240℃, indicating that they have good thermal stability, thereby better resisting thermal shrinkage of the porous base film, improving the heat resistance of the isolation film, and improving the reliability of the secondary battery cell.

[0029] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the glass transition temperature of the heat-resistant organic particles is greater than or equal to 200°C or the heat-resistant organic particles have no glass transition temperature. The glass transition temperature of the heat-resistant organic particles being greater than or equal to 200°C or the heat-resistant organic particles having no glass transition temperature indicates that the heat resistance and thermal stability of the heat-resistant organic particles are good, thereby the heat-resistant organic particles 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.

[0030] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the swelling degree of the heat-resistant organic particles 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 is less than or equal to 3%. The heat-resistant organic particles have a small swelling degree in the organic solvent, and the structural stability of the heat-resistant organic particles 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 film during use.

[0031] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the dissolution rate of the heat-resistant organic particles 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 is less than or equal to 3%. The heat-resistant organic particles have a small dissolution rate in the organic solvent, and the structural stability of the heat-resistant organic particles during long-term use of the secondary battery cell is high, and the chemical stability of the heat-resistant organic particles in the electrolyte is high, thereby the secondary battery cell can have a longer cycle stability.

[0032] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer, and the heat-resistant organic particles have no melting point. The heat-resistant organic particles having no melting point indicates that the heat resistance and thermal stability of the heat-resistant organic particles are good. By locating the heat-resistant organic particles 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 heat-resistant organic particles in the porous coating can better generate a force to resist the shrinkage of the porous base film, thereby the heat shrinkage of the whole separator film can be better improved, and the heat resistance of the separator film can be improved.

[0033] In some embodiments, the heat-resistant organic particles include at least one of a thermosetting resin polymer or a cross-linked polymer.

[0034] Optionally, the heat-resistant organic particles include one or more of a phenolic resin-based organic particle, a polymer particle containing a triazine ring structure unit, a cross-linked styrene-based organic particle, and a silicon-containing organic cross-linked resin particle.

[0035] In some embodiments, the heat-resistant organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles are thermosetting resol.

[0036] In some embodiments, the heat-resistant organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles have no glass transition temperature.

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

[0038] In some embodiments, the heat-resistant organic particles include phenolic resin-based organic particles, and the phenolic resin-based organic particles have a volume distribution particle size Dv50 of 160-800 nm. The volume distribution particle size Dv50 of the polymer particles of the phenolic resin-based organic particles is within the above range, which is beneficial to the isolation film having good heat resistance and air permeability.

[0039] In some embodiments, the heat-resistant 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. The triazine ring structure is rigid, which can make the polymer particles have better heat resistance.

[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 heat-resistant organic particles include polymer particles containing triazine ring structural units, and the polymer particles containing triazine ring structural units have no glass transition temperature.

[0043] In some embodiments, the heat-resistant 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 is 290-345°C.

[0044] In some embodiments, the heat-resistant organic particles include polymer particles containing triazine ring structural units, and the volume distribution particle size Dv50 of the polymer particles containing triazine ring structural units is 160 nm-800 nm. The volume distribution particle size Dv50 of the polymer particles containing triazine ring structural units in the above range is beneficial to the isolation film having 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-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.

[0051] In some embodiments, the heat resistant organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles include styrene or styrene derivative structural units and crosslinking structural units.

[0052] 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, and 2,5-dimethylstyrene structural units.

[0053] Optionally, the crosslinking structural units include one or more of divinylbenzene structural units, ethylene glycol dimethacrylate structural units, pentaerythritol tetraacrylate 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, tripropylene glycol diacrylate structural units, N,N-methylenebisacrylamide structural units, N,N'-vinylbisacrylamide structural units, 1,3,5-triacryloylhexahydro-1,3,5-triazine structural units, and trisallyl isocyanurate structural units.

[0054] In some embodiments, the heat resistant 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 to 165°C.

[0055] In some embodiments, the heat-resistant 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℃-388℃.

[0056] In some embodiments, the heat-resistant organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles have a volume distribution particle size Dv50 of 80nm-300nm. The volume distribution particle size Dv50 of the crosslinked styrene-based organic particles within the above range is conducive to the insulating film having good heat resistance and air permeability.

[0057] In some embodiments, the heat-resistant organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles contain benzene ring structures. The benzene ring structure is rigid, which can make the silicon-containing organic crosslinked resin particles have better heat resistance. By using the silicon-containing organic crosslinked resin particles containing benzene ring structures in the porous coating of the insulating film, a better force can be generated to resist the shrinkage of the porous base film, thereby improving the overall thermal shrinkage of the insulating film, improving the heat resistance of the insulating film, and improving the reliability of the secondary battery cell.

[0058] Optionally, the silicon-containing organic crosslinked 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.

[0059] In some embodiments, the heat-resistant organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles include crosslinked structure units, and the crosslinked structure units include divinyl benzene structure units.

[0060] Optionally, the crosslinked structure units further include one or more of divinyl glycol ether structure units, triethylene glycol divinyl ether structure units, maleic acid diallyl ester structure units, ethylene glycol dimethyl acrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethyl adipic acid bis[2-ethylaziridine] structure units, 1,1-sebacic acid bis[2-methylaziridine] structure units, 1,1-(1,3-phenylene dicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tri(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tri(3-aziridinyl) propionate structure units.

[0061] In some embodiments, the heat-resistant organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles have no glass transition temperature.

[0062] In some embodiments, the heat-resistant organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles have an initial thermal weight loss temperature T 3d 240°C-330°C.

[0063] In some embodiments, the heat-resistant organic particles include silicon-containing organic crosslinked resin particles, and the silicon-containing organic crosslinked resin particles have a volume distribution particle size Dv50 of 80 nm-800 nm. The volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles within the above range is conducive to the porous coating of the separation membrane having good heat resistance and air permeability.

[0064] In some embodiments, the non-fluoropolymer binder particles have an average particle size of 6 μm-15 μm.

[0065] In some embodiments, the non-fluoropolymer binder particles include aggregates of primary particles.

[0066] In some embodiments, the non-fluoropolymer binder particles have a glass transition temperature of 0°C-70°C.

[0067] Optionally, the non-fluoropolymer binder particles include a hard monomer, a soft monomer, and a crosslinking monomer. Optionally, the crosslinking monomer includes at least one of a hydroxyl group, a carboxyl group, an ester group, an amide group, a sulfonic acid group, and a sulfonate.

[0068] In some embodiments, the hard monomer includes one or more of methyl methacrylate, ethyl methacrylate, styrene, acrylonitrile, and methacrylonitrile.

[0069] In some embodiments, the soft monomer includes one or more of ethyl acrylate, n-butyl acrylate, isooctyl acrylate, octyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, lauryl methacrylate, and n-octyl methacrylate.

[0070] In some embodiments, the crosslinking monomer includes one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, diacetone acrylamide, acryloyl ethyl acrylate, acrylic acid, methacrylic acid, itaconic acid, styrene sulfonic acid, and sodium vinyl sulfonate.

[0071] In some embodiments, the non-fluoropolymer binder particles comprise a first glass transition temperature T g and a second glass transition temperature T g , and the first glass transition temperature and the second glass transition temperature are different.

[0072] In some embodiments, the first glass transition temperature T g is less than or equal to 25 °C, optionally from -20 °C to 25 °C.

[0073] In some embodiments, the second glass transition temperature T g is greater than 25 °C, optionally from 26 °C to 70 °C.

[0074] In some embodiments, the non-fluoropolymer binder particles comprise an acrylate copolymer, and / or the non-fluoropolymer binder particles comprise at least one of an ester group, a carboxyl group, an acrylamide group, a carbonyl group, an amide group, a nitrile group.

[0075] In some embodiments, the non-fluoropolymer binder particles comprise a first polymer and a second polymer, the first polymer and the second polymer each comprise an acrylate copolymer.

[0076] In some embodiments, the first polymer and / or the second polymer comprises a first polymerized monomer, the structure of the first polymerized monomer comprises:

[0077] R1comprises a hydrogen atom or an alkyl group of 1-12 carbon atoms, R2comprises an alkyl group of 1-12 carbon atoms.

[0078] In some embodiments, the first polymer comprises a second polymerized monomer, the structure of the second polymerized monomer comprises:

[0079] R3comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1-6 carbon atoms.

[0080] In some embodiments, the first polymer and / or the second polymer comprises a third polymerized monomer, the structure of the third polymerized monomer comprises:

[0081] R4comprises a hydrogen atom or an alkyl group of 1-6 carbon atoms, R5comprises a hydrogen atom, a hydroxyl-substituted alkyl group of 1-6 carbon atoms, or an alkoxy group of 1-6 carbon atoms.

[0082] In some embodiments, the second polymer comprises a fourth polymerized monomer, the structure of the fourth polymerized monomer comprises:

[0083] R6 includes a hydrogen atom or an alkyl group of 1-6 carbon atoms.

[0084] In some embodiments, the mass ratio of the first polymer to the second polymer is 1:(0.1-10), which can be 1:(0.5-3).

[0085] In a second aspect, the present disclosure provides a secondary battery cell including a positive electrode tab, a negative electrode tab, and the separator of the first aspect of the present disclosure, the separator being disposed between the positive electrode tab and the negative electrode tab.

[0086] In a third aspect, the present disclosure provides a battery device including a plurality of the secondary battery cell of the second aspect of the present disclosure.

[0087] In a fourth aspect, the present disclosure provides an electric device including the secondary battery cell of the second aspect of the present disclosure or the battery device of the third aspect of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0088] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments of the present disclosure will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings.

[0089] FIG. 1 shows a schematic diagram of a secondary battery cell according to some embodiments of the present disclosure.

[0090] FIG. 2 shows a schematic diagram of an electric device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0091] Hereinafter, specific embodiments of the separator, the secondary battery cell, the battery device, and the electric device of the present disclosure will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters known to those skilled in the art, repeated descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0092] The ranges disclosed herein are defined by their lower and upper endpoints, given that a range is defined by selecting a lower endpoint and an upper endpoint, the selected lower and upper endpoints define the boundaries of the particular range. Ranges defined by endpoints can be either inclusive or exclusive of the endpoints, and can be arbitrarily combined, i.e., any lower endpoint can be combined with any upper endpoint to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Also, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all of the individual real combinations that fall between "a" and "b", where "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand way of describing those numerical combinations. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0093] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0094] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0095] Unless otherwise specified, all steps of the present disclosure can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0096] Unless otherwise specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects, and are not used to describe a particular order or primary and secondary relationship.

[0097] In the present disclosure, the terms "a plurality of", "a plurality of" refer to two or more.

[0098] In the description of the embodiments of the present disclosure, if there is no special indication, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "below", "under" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0099] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25°C.

[0100] 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.

[0101] The secondary battery cell provided by the embodiments of the present disclosure can include but is not limited to lithium battery cells, sodium battery cells, such as lithium ion battery cells, sodium ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0102] The secondary battery cell provided by the embodiments of the present disclosure includes an electrode assembly. The electrode assembly can be a winding structure or a stacking structure, which is not limited in the embodiments of the present disclosure. The secondary battery cell further includes an outer package, which can be used to package the electrode assembly. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

[0103] The battery apparatus mentioned in the embodiments of the present disclosure can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of secondary battery cells connected in series, in parallel or in a mixed manner through a busbar component.

[0104] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of secondary battery cells.

[0105] As an example, the battery cell assembly can be a battery module. The battery module is formed by arranging and fixing a plurality of secondary battery cells into one independent module. As an example, the battery module can be formed by bundling a plurality of secondary battery cells with a cable tie.

[0106] In some embodiments, the battery device can be a battery pack. The battery pack includes a case and one or more battery cell assemblies. The battery cell assemblies are accommodated in the case.

[0107] As an example, the battery cell assembly can be a battery module. The battery cell assembly can be accommodated in the case by fixing the battery module in the case.

[0108] As an example, the battery cell assembly can also be accommodated in the case by directly fixing a plurality of secondary battery cells in the case.

[0109] As an example, the case can include a first case and a second case. The first case and the second case are fastened so that an enclosed space is formed inside the case to accommodate the battery cell assembly. Here, enclosed means covered or closed, which can be sealed or unsealed. The first case can be a top cover or a bottom plate.

[0110] As an example, the case can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that an enclosed space is formed inside the case to accommodate the battery cell assembly.

[0111] In some embodiments, the case can be part of the chassis structure of a vehicle. For example, part of the case can be at least part of the floor of the vehicle, or part of the case can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0112] The technical solutions described in the embodiments of the present disclosure are applicable to various electric devices using secondary battery cells and battery devices. For example, the electric devices can be, but are 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.

[0113] 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.

[0114] In the context of the present disclosure, the "heat-resistant organic particles" function to improve heat resistance in the porous coating of the separator film and have substantially no adhesion. The "non-fluoropolymer binder particles" function to improve adhesion of the separator film to the pole piece in the porous coating of the separator film and have substantially no high-temperature resistance.

[0115] The melting point can be tested according to the following method: 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: increase the temperature from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, then decrease the temperature from 200°C to -40°C at a rate of 10°C / min, and then increase the temperature to 300°C at a rate of 10°C / min. Determine whether the heat-resistant organic particles have a melting point below 300°C by the DSC curve. No melting point of the organic particles means that the DSC curve of the organic particles has no melting peak.

[0116] The oxidation peak potential of the cyclic voltammetry curve of the heat-resistant organic particles can be tested according to the following method: take heat-resistant organic particles, binder polyacrylate, and conductive agent conductive carbon black, and 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, and the concentration is 1 mol / L. 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.

[0117] The swelling degree of the heat-resistant organic particles can be tested according to the following method: take an appropriate amount of sample (for example, about 1 g), record its mass as m1, place it in a semi-permeable membrane sample bag, seal it, and the sample bag can permeate the solvent but cannot pass through the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50 g) and immerse it at 60°C for 7 days, then take out the sample bag, take out the sample from the sample bag, wipe off the excess solvent, and weigh the mass of the sample again m2; swelling degree = (m2-m1) / m1x100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) according to a volume ratio of 3:7.

[0118] The dissolution rate of the heat-resistant organic particles can be tested according to the following method: take an appropriate amount of sample (for example, about 1 g), record the mass as m1, place it in a semi-permeable membrane sample bag, seal it, record the total mass of the sample bag m2, the sample bag can permeate the solvent, but cannot permeate the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50 g) at 60°C for 7 days, then take out the sample bag, drain, dry, and weigh the total mass of the sample bag again m3; dissolution rate = (m2-m3) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) mixed in a volume ratio of 3:7.

[0119] The glass transition temperature T of the heat-resistant organic particles g The glass transition temperature T of the heat-resistant organic particles can be tested according to the following method: take an appropriate amount of sample (for example, about 1 g), record the mass as m1, place it in a semi-permeable membrane sample bag, seal it, record the total mass of the sample bag m2, the sample bag can permeate the solvent, but cannot permeate the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50 g) at 60°C for 7 days, then take out the sample bag, drain, dry, and weigh the total mass of the sample bag again m3; dissolution rate = (m2-m3) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) mixed in a volume ratio of 3:7. g , or determine whether the heat-resistant organic particles have a glass transition temperature T below 300°C g .

[0120] The glass transition temperature T of the heat-resistant organic particles g refers to the transition temperature from glass state to high-elasticity state, which shows a step change on the DSC curve.

[0121] The heat-resistant organic particles have no glass transition temperature T g refers to the absence of a step change in the DSC curve of the organic particles below 300°C.

[0122] The initial thermal weight loss temperature T 3d refers to the temperature corresponding to a 3% loss in the mass of the sample relative to the initial mass in the thermal gravimetric analysis. The initial thermal weight loss temperature T of the heat-resistant organic particles 3d The initial thermal weight loss temperature T of the heat-resistant organic particles can be tested according to the following method: take an appropriate amount of sample (for example, about 1 g), record the mass as m1, place it in a semi-permeable membrane sample bag, seal it, record the total mass of the sample bag m2, the sample bag can permeate the solvent, but cannot permeate the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50 g) at 60°C for 7 days, then take out the sample bag, drain, dry, and weigh the total mass of the sample bag again m3; dissolution rate = (m2-m3) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) mixed in a volume ratio of 3:7. 3d .

[0123] 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 small beaker, 20 ml of deionized water is added, and ultrasonic treatment is performed at 53 KHz / 120 W for 5 min to ensure that the sample is completely dispersed. After the light path system is cleaned, the background is automatically tested. The solution to be tested is stirred to make it uniformly dispersed, and then placed in the sample cell as required to start measuring the particle size. The testing instrument can be a MasterSizer 3000 laser particle size analyzer.

[0124] The average particle size of the particles can be tested according to the following method: using a scanning electron microscope according to JY / T010-1996, SEM images of the separator film are obtained, a test sample with a length of 50 mm and a width of 100 mm is randomly selected on the separator film, a plurality of test regions (for example, 5) are randomly selected in the test sample, and the particle size of each particle in each test region is read under a certain magnification (for example, more than 500 times). The number and particle size values of the particles in each test region are counted, and the arithmetic mean of the particle sizes of all particles in each test region is taken as the average particle size of the particles. In order to ensure the accuracy of the test results, a plurality of test samples (for example, 10) can be taken for the above test, and the average value of each test sample is taken as the final test result. The testing instrument can be a ZEISS Sigma 300. It should be noted that when the particles are irregularly shaped, the distance between the two farthest points on the particle is taken as the particle size of the particle.

[0125] It can be understood that the electrode assembly is formed by bonding the positive electrode sheet, the negative electrode sheet and the separator film. The electrode assembly has a certain hardness, that is, because the electrode sheets and the separator film bonded together are in close contact with each other and support each other, a structure with a certain thickness is formed, and the structure with a certain thickness has a certain hardness. The negative electrode will swell during the charging and discharging process. If the bonding force is weak, a gap will be formed between the electrode sheet and the separator film, the electrode sheet and the separator film cannot be in close contact with each other and support each other, resulting in a loose electrode assembly, a low hardness, a low assembly qualification rate, and a poor thickness consistency of the finished secondary battery cell. At this time, the cycle performance of the electrode assembly will be poor.

[0126] At present, the main binder particles used in the porous coating of the separator film are polyvinylidene fluoride (PVDF) particles, but the bonding effect of the PVDF particles needs to be further improved at the present stage.

[0127] Based on this, the present embodiment provides a separator film which can make the secondary battery cell using it have high quality energy density, high reliability and good cycle performance.

[0128] 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 including heat-resistant organic particles and non-fluoropolymer binder particles.

[0129] By locating the heat-resistant organic particles on the porous base film, when the porous base film is transformed from a glassy state to a high-elastic state, the heat-resistant organic particles in the porous coating layer will generate a force resisting the shrinkage of the porous base film, thereby improving the overall thermal shrinkage of the separator film, enhancing the heat resistance of the separator film, and improving the reliability of the secondary battery cell. In addition, the heat-resistant organic particles generally have a smaller true density, thereby enabling the secondary battery cell using the separator film of the present disclosure to have a higher mass energy density. At the same time, the porous coating layer of the separator film includes non-fluoropolymer binder particles, which can further enhance the adhesion between the separator film and the electrode sheet, thereby enabling the separator film to be closely bonded to the electrode sheet, improving the hardness of the electrode assembly, and improving the cycle performance of the secondary battery cell.

[0130] Therefore, the separator film of the present disclosure used in the secondary battery cell can have high mass energy density, high reliability, and good cycle performance.

[0131] In some embodiments, the heat-resistant organic particles can have a true density of 1.0 g / cm 3 -2.0 g / cm 3 . Alternatively, the heat-resistant organic particles can have a true density of 1.0 g / cm 3 -1.8 g / cm 3 .

[0132] Currently, the true density of inorganic particles such as boehmite and alumina is generally 2.5 g / cm 3 -3.5 g / cm 3 . The heat-resistant organic particles of the present disclosure have a smaller true density, thereby enabling the secondary battery cell using the separator film of the present disclosure to have a higher mass energy density.

[0133] In some embodiments, the non-fluoropolymer binder particles can be embedded in the heat-resistant organic particles and form protrusions on the surface of the porous coating layer.

[0134] Alternatively, the mass content of the heat-resistant organic particles in the porous coating layer can be 68%-92%.

[0135] Alternatively, the mass content of the non-fluoropolymer binder particles in the porous coating layer can be 5%-30%.

[0136] Optionally, the porous coating further comprises a binder, and the binder is a non-particulate binder. Optionally, the binder can include, but is not limited to, one or more of polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0137] Optionally, the porous coating can further comprise a dispersant. The dispersant can include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, and the like.

[0138] In some embodiments, the porous coating can further comprise fluoropolymer binder particles, which can be embedded in the heat-resistant organic particles and form protrusions on the surface of the porous coating.

[0139] Optionally, the fluoropolymer binder particles can comprise aggregates of primary particles. The aggregates of primary particles can also be referred to as secondary particles.

[0140] Optionally, the fluoropolymer binder particles can have a particle size greater than that of the non-fluoropolymer binder particles.

[0141] Optionally, the fluoropolymer binder particles can comprise vinylidene fluoride-based polymers, such as homopolymers of vinylidene fluoride monomers (VDF) and / or copolymers of vinylidene fluoride monomers and comonomers. The comonomers can include at least one of olefin monomers, fluorine-containing olefin monomers, chlorine-containing olefin monomers, acrylate monomers, acrylic monomers, and fluorine ether monomers. Optionally, the comonomers can include at least one of trifluoroethylene (VF3), chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl) ether (such as perfluoro(methyl vinyl) ether PMVE, perfluoro(ethyl vinyl) ether PEVE, perfluoro(propyl vinyl) ether PPVE), perfluoro(1,3-dioxolane), and perfluoro(2,2-dimethyl-1,3-dioxolane) (PDD).

[0142] The mass content of the fluoropolymer binder particles and the non-fluoropolymer binder particles in the porous coating can be adjusted according to actual needs. From the perspective of improving the adhesion between the separator and the electrode sheet, the mass content of the non-fluoropolymer binder particles can be increased, and the mass content of the fluoropolymer binder particles can be decreased. From the perspective of forming a larger charge / discharge expansion space between the separator and the electrode sheet, the mass content of the fluoropolymer binder particles can be increased, and the mass content of the non-fluoropolymer binder particles can be decreased.

[0143] In some embodiments, the mass content of the non-fluoropolymer binder particles in the porous coating can be greater than the mass content of the fluoropolymer binder particles in the porous coating.

[0144] In other embodiments, the porous coating comprises a heat resistant layer and a bonding layer, the bonding layer is disposed on at least a portion of the surface of the heat resistant layer or the porous base film, the heat resistant organic particles are disposed in the heat resistant layer, and the non-fluoropolymer binder particles are disposed in the bonding layer. For example, in some embodiments, the heat resistant layer is disposed on both sides of the porous base film, and the bonding layer is disposed on at least a portion of the surface of the heat resistant layer; in some embodiments, the heat resistant layer is disposed on one side of the porous base film, and the bonding layer is disposed on at least a portion of the surface of the other side of the porous base film.

[0145] Optionally, the mass content of the heat resistant organic particles in the heat resistant layer can be 50%-99%, optionally 60%-99%, 70%-99%, 80%-99%, 85%-99%, 90%-99%, 92%-99%, 80%-97%, 85%-97%, 90%-97%, 80%-95%, 85%-95%, 90%-95%.

[0146] Optionally, the mass content of the non-fluoropolymer binder particles in the bonding layer can be 35%-95%.

[0147] The heat resistant layer comprises a first binder, and the bonding layer comprises a second binder. The first binder and the second binder are non-particulate binders. Optionally, the first binder and the second binder can independently include, but are not limited to, one or more of polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0148] Optionally, the heat resistant layer can further comprise a dispersant. The dispersant can include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, and the like.

[0149] Optionally, the bonding layer can further comprise a dispersant. The dispersant can include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, and the like.

[0150] Optionally, the bonding layer can further comprise a wetting agent.

[0151] In some embodiments, the bonding layer can further comprise fluoropolymer binder particles.

[0152] Optionally, the fluoropolymer binder particles can comprise aggregates of primary particles. The aggregates of primary particles can also be referred to as secondary particles.

[0153] Optionally, the particle size of the fluorine-containing polymer binder particles can be greater than the particle size of the non-fluorine polymer binder particles.

[0154] Optionally, the fluorine-containing polymer binder particles can include a vinylidene fluoride-based polymer, such as a homopolymer of vinylidene fluoride monomers (VDF) and / or a copolymer of vinylidene fluoride monomers and a comonomer. 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, a fluorinated ether monomer. Optionally, the comonomer can include at least one of vinyl fluoride (VF3), chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl) ether (such as perfluoro(methyl vinyl) ether PMVE, perfluoro(ethyl vinyl) ether PEVE, perfluoro(propyl vinyl) ether PPVE), perfluoro(1,3-dioxolane), and perfluoro(2,2-dimethyl-1,3-dioxolane) (PDD).

[0155] The mass content of the fluorine-containing polymer binder particles and the non-fluorine polymer binder particles in the bonding layer can be adjusted according to actual needs. From the perspective of improving the adhesion between the separator and the electrode sheet, the mass content of the non-fluorine polymer binder particles can be increased, and the mass content of the fluorine-containing polymer binder particles can be reduced. From the perspective of forming a larger charge and discharge expansion space between the separator and the electrode sheet, the mass content of the fluorine-containing polymer binder particles can be increased, and the mass content of the non-fluorine polymer binder particles can be reduced.

[0156] In some embodiments, the mass content of the non-fluorine polymer binder particles in the bonding layer can be greater than the mass content of the fluorine-containing polymer binder particles in the bonding layer.

[0157] In some embodiments, the average particle size of the non-fluorine polymer binder particles can be 6 μm-15 μm, such as 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a range consisting of any of the aforementioned values.

[0158] In some embodiments, the non-fluorine polymer binder particles can include aggregates of primary particles. The aggregates of primary particles can also be referred to as secondary particles.

[0159] In some embodiments, the shape of the non-fluorine polymer binder particles can include a spherical shape.

[0160] In some embodiments, the heat-resistant organic particles can include at least one of a thermoplastic resin polymer, a thermosetting resin polymer, or a cross-linked polymer.

[0161] In some embodiments, the thermoplastic resin polymer can include one or more of polyphenylene sulfide-based organic particles, polyimide-based organic particles, polysulfone-based organic particles, polyethersulfone-based organic particles, polyphenylene sulfone-based organic particles, polybenzimidazole-based organic particles, polyamide-imide-based organic particles, polyethyleneimine-based organic particles, polyether ether ketone-based organic particles.

[0162] In some embodiments, the thermosetting resin polymer can include one or more of phenol formaldehyde resin-based organic particles, polymer particles containing triazine ring structure units, epoxy resin-based organic particles, unsaturated polyester resin-based organic particles, urea-formaldehyde resin-based organic particles, furan resin-based organic particles.

[0163] 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.

[0164] In some embodiments, the heat-resistant organic particles can include at least one of the thermosetting resin polymer or the cross-linked polymer.

[0165] In some embodiments, the heat-resistant organic particles can include at least one of the thermosetting resin polymer or the cross-linked polymer, and the cyclic voltammogram of the heat-resistant organic particles in the first cycle has no oxidation peak in a voltage range of 2.5 V to 4.4 V.

[0166] The cyclic voltammogram of the heat-resistant organic particles in the first cycle has no oxidation peak in a voltage window range of greater than or equal to 2.5 V and less than 4.4 V, indicating that the heat-resistant organic particles are stable in the voltage window range of greater than or equal to 2.5 V and less than 4.4 V and no electrochemical oxidation-reduction 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 quality energy density.

[0167] In some embodiments, the heat-resistant organic particles can include at least one of the thermosetting resin polymer or the cross-linked polymer, and the heat-resistant organic particles have an initial thermal weight loss temperature T 3d may be greater than or equal to 240℃.

[0168] The heat-resistant organic particles have an initial thermal weight loss temperature T 3d , indicating that they have good thermal stability, thereby better resisting thermal shrinkage of the porous base film, improving the heat resistance of the isolation film, and improving the reliability of the secondary battery cell.

[0169] In some embodiments, the heat-resistant organic particles can include at least one of the thermosetting resin polymer or the cross-linked polymer, and the heat-resistant organic particles have a glass transition temperature greater than or equal to 200℃ or the heat-resistant organic particles can have no glass transition temperature.

[0170] The glass transition temperature of the heat-resistant organic particles is greater than or equal to 200°C or the heat-resistant organic particles have no glass transition temperature, which indicates that the heat resistance and thermal stability of the heat-resistant organic particles are good, so that the heat-resistant organic particles 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.

[0171] In some embodiments, the heat-resistant organic particles can include at least one of a thermosetting resin polymer or a cross-linked polymer, and the swelling degree of the heat-resistant organic particles in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 3% when immersed in the mixed solvent at 60°C for 7 days.

[0172] The heat-resistant organic particles have a small swelling degree in an organic solvent, and have high structural stability during long-term use of the secondary battery cell, so that the problem of a decrease in the air permeability of the separator film during use is improved.

[0173] In some embodiments, the heat-resistant organic particles can include at least one of a thermosetting resin polymer or a cross-linked polymer, and the elution rate of the heat-resistant organic particles in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 3% when immersed in the mixed solvent at 60°C for 7 days.

[0174] The heat-resistant organic particles have a small elution rate in an organic solvent, and have high structural stability during long-term use of the secondary battery cell and high chemical stability in the electrolyte, so that the secondary battery cell can have longer cycle stability.

[0175] In some embodiments, the heat-resistant organic particles can include at least one of a thermosetting resin polymer or a cross-linked polymer, and the heat-resistant organic particles have no melting point.

[0176] The heat-resistant organic particles have no melting point, which indicates that the heat resistance and thermal stability of the heat-resistant organic particles are good. By locating the heat-resistant organic particles on the porous base film, the porous coating is still stable when the porous base film is transformed from a glassy state to an elastomeric state, and the heat-resistant organic particles in the porous coating can better generate a force to resist the shrinkage of the porous base film, so that the thermal shrinkage of the entire separator film can be better improved, and the heat resistance of the separator film can be improved.

[0177] In some embodiments, the heat-resistant organic particles can include one or more of a phenol formaldehyde resin-based organic particle, a polymer particle containing a triazine ring structure unit, a cross-linked styrene-based organic particle, and a silicon-containing organic cross-linked resin particle.

[0178] The heat-resistant 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 tested by gel permeation chromatography, nor can the molecular weight of the heat-resistant organic particles be tested by gel permeation chromatography.

[0179] [phenolic resin-based organic particles]

[0180] In some embodiments, the phenolic resin-based organic particles are thermosetting resins.

[0181] In some embodiments, the phenolic resin-based organic particles are thermosetting resol.

[0182] In some embodiments, the phenolic resin-based organic particles do not have an oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.4V.

[0183] In some embodiments, the swelling degree of the phenolic resin-based organic particles in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C constant temperature for 7 days is less than or equal to 3%.

[0184] In some embodiments, the dissolution rate of the phenolic resin-based organic particles in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C constant temperature for 7 days is less than or equal to 3%.

[0185] In some embodiments, the phenolic resin-based organic particles have no melting point.

[0186] In some embodiments, the phenolic resin-based organic particles have no glass transition temperature.

[0187] The phenolic resin-based organic particles have no glass transition temperature, 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 film, and improve the reliability of the secondary battery cell.

[0188] In some embodiments, the phenolic resin-based organic particles have an initial thermal weight loss temperature T 3d may be 300°C-350°C.

[0189] The phenolic resin-based organic particles have an initial thermal weight loss temperature T 3d is high, indicating that they have good 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.

[0190] In some embodiments, the volume distribution particle size Dv50 of the phenolic resin-based organic particles can be 160nm-800nm.

[0191] The volume distribution particle size Dv50 of the polymer particles of the phenolic resin-based organic particles is within the above range, which is beneficial to the heat resistance and air permeability of the separation membrane.

[0192] The raw material of the phenolic resin-based organic particles can include a phenolic compound and an aldehyde compound. In some embodiments, the phenolic compound can include one or more of phenol, hydroquinone, resorcinol, catechol, cresol, and cardanol. In some embodiments, the aldehyde compound can include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0193] The resol-based material generally has a low melting point and cannot meet the heat resistance requirements of the separation membrane. Therefore, the present disclosure provides a phenolic resin-based organic particle, which has no melting point. The present disclosure also provides a method for preparing the phenolic resin-based organic particle.

[0194] The method for preparing the phenolic resin-based organic particle includes the following steps: providing a resol-based material; curing the resol-based material at a first temperature and in a first atmosphere for a first time, then curing the resol-based material at a second temperature and in a second atmosphere for a second time, and finally crushing to obtain the phenolic resin-based organic particle. The first temperature is 90-180°C, and the second temperature is 190-290°C.

[0195] The phenolic resin-based organic particle prepared by the present disclosure is a thermosetting resol.

[0196] The first temperature is 90-180°C, for example, it can be 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 of the above values.

[0197] The first temperature is within the above range, which can make the curing of the resol-based material in the first stage more uniform and sufficient, thereby obtaining a phenolic resin-based organic particle with good heat resistance and no melting point below 300°C.

[0198] Alternatively, the first temperature is 90-180°C, 100-180°C, 110-180°C, 100-165°C, or 110-165°C.

[0199] The first temperature is within the above range, which can obtain a phenolic resin-based organic particle with better heat resistance.

[0200] The second temperature can be in the range of 190°C to 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.

[0201] The second temperature in the above range can make the phenolic resin-based organic particles more fully cured, and obtain phenolic resin-based organic particles with good heat resistance and no melting point below 300°C.

[0202] Alternatively, the second temperature can be in the range of 200°C to 285°C, 200°C to 280°C.

[0203] The second temperature in the above range can obtain phenolic resin-based organic particles with better heat resistance.

[0204] In some embodiments, the first time can be in the range of 1h to 5h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h, 5h, or a range formed by any two of the above values.

[0205] The first time in the above range can make the resol-based material more uniformly and fully cured in the first stage, and thus can obtain phenolic resin-based organic particles with better heat resistance.

[0206] In some embodiments, the second time can be in the range of 1h to 6h, for example, 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, or a range formed by any two of the above values.

[0207] The second time in the above range can make the phenolic resin-based organic particles more fully cured and have better heat resistance.

[0208] 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. Alternatively, the volume fraction of oxygen in the oxygen-containing atmosphere can be in the range of 5% to 50%. Alternatively, the inert gas can include, but is not limited to, one or more of nitrogen, argon, and helium.

[0209] Optionally, the first atmosphere is an oxygen-containing atmosphere, and the volume fraction of oxygen in the oxygen-containing atmosphere can be 10% to 30%. More optionally, the first atmosphere can be an air atmosphere.

[0210] 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% to 50%. Optionally, the inert gas can include one or more of nitrogen, argon, and helium.

[0211] Optionally, the second atmosphere is an oxygen-containing atmosphere, and the volume fraction of oxygen in the oxygen-containing atmosphere can be 10% to 30%. More optionally, the second atmosphere can be an air atmosphere.

[0212] In some embodiments, the method for preparing the phenolic resin-based organic particles further includes a sieving treatment and a magnetic removal treatment after the crushing treatment.

[0213] The resol resin-based material can be commercially available or synthesized according to a method known in the art. In some embodiments, the method for preparing the resol resin-based material includes the following steps: reacting a phenolic compound and an aldehyde compound under catalysis of an alkaline substance to obtain the resol resin-based material.

[0214] Optionally, the alkaline substance can include one or more of ammonia, NaOH, and Na2CO3.

[0215] Optionally, the phenolic compound can include one or more of phenol, p-dihydroxybenzene, m-dihydroxybenzene, o-dihydroxybenzene, cresol, and cardanol.

[0216] Optionally, the aldehyde compound can include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propyl aldehyde, n-butyl aldehyde, glyoxal, and furfural.

[0217] [Polymer particles containing triazine ring structure units]

[0218] The triazine ring structure is rigid, which can make the polymer particles have good heat resistance.

[0219] The polymer particles containing triazine ring structure units of the present disclosure include a bridging structure connecting the triazine ring structure units.

[0220] The polymer particles containing triazine ring structure units have a plurality of triazine ring structure units in the molecular structure, and the bridging structure refers to a group connecting the triazine ring structure units, and each bridging structure is the same or different.

[0221] 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.

[0222] More optionally, the bridging structure can include one or a combination of two or more of methylene, methylene ether, methylene amine.

[0223] In some embodiments, the triazine ring structural units of the polymer particles containing triazine ring structural units can further have substituents thereon, which can include a combination of one or more of alkyl, alkenyl, phenyl, cycloalkyl, amine, hydroxyl, halogen.

[0224] In some embodiments, the polymer particles containing triazine ring structural units can 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-polycarboxylic acid polymers and derivatives thereof, etherified melamine formaldehyde-polyamine amide polymers and derivatives thereof.

[0225] In some embodiments, the melamine formaldehyde polymers and derivatives thereof can include melamine formaldehyde polymers and derivatives thereof.

[0226] Optionally, the melamine formaldehyde polymers and derivatives thereof can include one or more of melamine formaldehyde, phenylated melamine formaldehyde, melamine-phenylated melamine 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, melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde.

[0227] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof can include etherified melamine formaldehyde polymers and derivatives thereof.

[0228] In some embodiments, the etherified melamine formaldehyde polymers and derivatives thereof can include 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.

[0229] Optionally, the etherified melamine formaldehyde polymers and derivatives thereof can include 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.

[0230] The etherified melamine formaldehyde polymer and its derivatives can include one or more of partially etherified melamine formaldehyde polymer and its derivatives, fully etherified melamine formaldehyde polymer and its derivatives. Alternatively, the etherified melamine formaldehyde polymer and its derivatives can include fully etherified melamine formaldehyde polymer and its derivatives.

[0231] In some embodiments, the etherified melamine formaldehyde polymer and its derivatives can include one or more of methyl etherified melamine formaldehyde, butyl etherified melamine formaldehyde, methyl etherified benzoguanamine formaldehyde, butyl etherified benzoguanamine formaldehyde.

[0232] The etherified melamine formaldehyde-polyol polymer and its derivatives refer to the product of high temperature cross-linking curing reaction of etherified melamine formaldehyde resin and polyol. Alternatively, the molar ratio of etherified melamine formaldehyde resin and polyol can be 1:2-1:6.

[0233] In some embodiments, the polyol can include one or more of dihydric alcohol, trihydric alcohol, tetrahydric alcohol. Alternatively, 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, polyester polyol, polyether polyol. More alternatively, the polyol can include one or more of ethylene glycol, 1,2-propanediol, 1,4-butanediol, polyvinyl alcohol, polyester polyol.

[0234] Alternatively, the polyester polyol can include one or more of polyethylene glycol adipate diol, poly-1,4-butanediol adipate diol, polypropylene glycol adipate diol, polyneopentyl glycol adipate diol, polyneopentyl glycol-1,6-hexanediol adipate diol, polyhexanediol adipate diol, polycarbonate diol, polycaprolactone diol.

[0235] Alternatively, the polyether polyol can include one or more of polypropylene oxide diol, polypropylene oxide triol, polytetrahydrofuran diol.

[0236] Alternatively, the molecular weight of the polyester polyol can be below 5000, optionally below 2000.

[0237] Alternatively, the molecular weight of the polyether polyol can be below 5000, optionally below 2000.

[0238] Alternatively, the molecular weight of the polyvinyl alcohol can be below 5000, optionally below 2000.

[0239] In some embodiments, the etherified melamine formaldehyde-polyol polymer and derivatives thereof can include one or more of a methyl etherified melamine formaldehyde-ethylene glycol polymer, a methyl etherified melamine formaldehyde-1,2-propanediol polymer, a methyl etherified melamine formaldehyde-1,4-butanediol polymer, a methyl etherified melamine formaldehyde-polyester polyol polymer, a methyl etherified melamine formaldehyde-polyvinyl alcohol polymer, a butyl etherified melamine formaldehyde-ethylene glycol polymer, a butyl etherified melamine formaldehyde-1,2-propanediol polymer, a butyl etherified melamine formaldehyde-1,4-butanediol polymer, a butyl etherified melamine formaldehyde-polyester polyol polymer.

[0240] The etherified melamine formaldehyde-polybasic acid polymer and derivatives thereof refer to the high-temperature cross-linking and curing reaction product of the etherified melamine formaldehyde resin and the polybasic acid. Optionally, the molar ratio of the etherified melamine formaldehyde resin to the polybasic acid can be 1:2-1:6.

[0241] In some embodiments, the polybasic acid can include one or more of a dibasic acid, a tribasic acid, a tetrabasic acid. Optionally, the polybasic 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, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic anhydride, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid. More optionally, the polybasic acid can include one or more of oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid, terephthalic acid.

[0242] In some embodiments, the etherified melamine formaldehyde-polybasic acid polymer and derivatives thereof 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.

[0243] The etherified melamine formaldehyde-polybasic amide polymer and derivatives thereof refer to the high-temperature cross-linking and curing reaction product of the etherified melamine formaldehyde resin and the polybasic amide. Optionally, the molar ratio of the etherified melamine formaldehyde resin to the polybasic amide can be 1:2-1:6.

[0244] In some embodiments, the polybasic amide can include one or more of oxalamide, malonamide, succinamide, adipamide, isophthalic imide. Alternatively, the polybasic amide can include one or more of oxalamide, malonamide, isophthalic imide.

[0245] In some embodiments, the etherified melamine aldehyde-polyamine amide polymer and derivatives thereof can include one or more of methyl etherified melamine formaldehyde-oxalamide polymer, methyl etherified melamine formaldehyde-malonamide polymer, methyl etherified melamine formaldehyde-isophthalic imide polymer, butyl etherified melamine formaldehyde-oxalamide polymer.

[0246] In some embodiments, the polymer particles containing triazine ring structural units have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.4V.

[0247] In some embodiments, the polymer particles containing triazine ring structural units have a swelling degree 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.

[0248] In some embodiments, the polymer particles containing triazine ring structural units have a dissolution rate 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.

[0249] In some embodiments, the polymer particles containing triazine ring structural units have no melting point.

[0250] In some embodiments, the polymer particles containing triazine ring structural units have no glass transition temperature.

[0251] The polymer particles containing triazine ring structural units have no glass transition temperature, 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 film, and improve the reliability of the secondary battery cell.

[0252] In some embodiments, the polymer particles containing triazine ring structural units have a starting thermal weight loss temperature T 3d may be 290°C-345°C.

[0253] The polymer particles containing triazine ring structural units have a starting thermal weight loss temperature T 3d is high, indicating that they have good 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.

[0254] In some embodiments, the volume distribution particle size Dv50 of the polymer particles containing triazine ring structural units can be 160 nm-800 nm.

[0255] The volume distribution particle size Dv50 of the polymer particles containing triazine ring structural units in the above range is beneficial for the isolation film to have good heat resistance and air permeability.

[0256] The present disclosure provides a polymer particle containing triazine ring structural units, which has no melting point. The present disclosure also provides a method for preparing the polymer particle containing triazine ring structural units.

[0257] The method for preparing the polymer particles containing triazine ring structural units comprises the following steps: providing a precursor containing triazine ring structure; heating and curing the precursor containing triazine ring structure in an oxygen-containing atmosphere, and then crushing to obtain the polymer particles containing triazine ring structural units. The heating and curing temperature is 180°C-290°C. After the heating and curing of the precursor containing triazine ring structure, a bridging structure is formed between the triazine ring structural units.

[0258] The heating and curing temperature is 180°C-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.

[0259] The heating and curing temperature in the above range can obtain the polymer particles containing triazine ring structural units, which have good heat resistance and no melting point below 300°C.

[0260] Optionally, the heating and curing temperature can be 200°C-285°C, 205°C-285°C, 215°C-285°C, 225°C-285°C.

[0261] In some embodiments, the heating and curing time can be 1h-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.

[0262] The time for heat curing is within the above range, which is advantageous for the formation of the polymer particles containing triazine ring structure units having better heat resistance from the resol resin containing triazine ring structure.

[0263] Optionally, the time for heat curing can be 2h-7h, 2.4h-7h, 2.8h-7h, 2h-6.6h, 2.4h-6.6h, 2.8h-6.6h.

[0264] 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.

[0265] In some embodiments, the polymer particles containing triazine ring structure units further include the steps of sieving and demagnetizing after the crushing treatment.

[0266] In some embodiments, the precursor containing triazine ring structure can include at least one of melamine formaldehyde resin, etherified melamine formaldehyde resin, a mixture of etherified melamine formaldehyde resin and at least one of polyol, polycarboxylic acid, polyamide.

[0267] In some embodiments, the precursor containing triazine ring structure can include melamine formaldehyde resin, which can be obtained by reacting an aldehyde compound with an amine-substituted triazine compound, and 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 above values. 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.

[0268] In some embodiments, the precursor containing a triazine ring structure can include an etherified melamine-aldehyde 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.

[0269] In some embodiments, the precursor containing a triazine ring structure includes a mixture of an etherified melamine-aldehyde resin and a polyol, the molar ratio of the etherified melamine-aldehyde resin to the polyol can be 1:2-1:6.

[0270] In some embodiments, the precursor containing a triazine ring structure includes a mixture of an etherified melamine-aldehyde resin and a polyol, the molar ratio of the etherified melamine-aldehyde resin to the polyol can be 1:2-1:6.

[0271] In some embodiments, the precursor containing a triazine ring structure includes a mixture of an etherified melamine-aldehyde resin and a polyol, the molar ratio of the etherified melamine-aldehyde resin to the polyol can be 1:2-1:6.

[0272] In some embodiments, the alcohol compound forming the etherified melamine-aldehyde resin can include one or more of methanol, ethanol, butanol.

[0273] In some embodiments, the aldehyde compound forming the melamine-aldehyde resin and the etherified melamine-aldehyde resin can include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0274] In some embodiments, the amine-substituted triazine compound forming the melamine-aldehyde resin and the etherified melamine-aldehyde 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, R4is selected from any one of -NH2, C1-C8 alkyl. Optionally, R3is selected from -NH2or -NHR4.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] In some embodiments, the etherified melamine aldehyde resin can include 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.

[0279] 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.

[0280] [Crosslinked styrene-based organic particles]

[0281] In some embodiments, the crosslinked styrene-based organic particles comprise styrene or styrene derivative structural units and crosslinking structural units.

[0282] The crosslinking structural units of the crosslinked styrene-based organic particles refer to structural units used to connect the styrene or styrene derivative structural units.

[0283] Optionally, the styrene or styrene derivative structural units can comprise 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.

[0284] Optionally, the crosslinking structural units can comprise one or more of divinylbenzene structural units, ethylene glycol dimethacrylate structural units, pentaerythritol tetraacrylate 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, tripropylene glycol diacrylate structural units, N,N-methylenebisacrylamide structural units, N,N'-vinylbisacrylamide structural units, 1,3,5-triacryloylhexahydro-1,3,5-triazine structural units, trisallyl isocyanurate structural units.

[0285] In some embodiments, the crosslinked styrene-based organic particles do not have an oxidation peak in a cyclic voltammogram of the first cycle in a voltage range of 2.5V to 4.4V.

[0286] In some embodiments, the crosslinked styrene-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.

[0287] In some embodiments, the crosslinked styrene-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.

[0288] In some embodiments, the crosslinked styrene-based organic particles have no melting point.

[0289] In some embodiments, the crosslinked styrene-based organic particles have a glass transition temperature T g may be 110°C-165°C.

[0290] Currently, the glass transition temperature T gsmall, usually below 100°C. The crosslinked styrene-based organic particles of the present disclosure have a glass transition temperature T g 110°C-165°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 thermal shrinkage of the entire separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0291] Optionally, the glass transition temperature T g may be 120°C-165°C, 130°C-165°C, 140°C-165°C, or 150°C-165°C.

[0292] In some embodiments, the initial thermal weight loss temperature T 3d may be 335°C-388°C.

[0293] The initial thermal weight loss temperature T 3d is high, indicating that it has 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.

[0294] In some embodiments, the volume distribution particle size Dv50 of the crosslinked styrene-based organic particles can be 80nm-300nm.

[0295] The volume distribution particle size Dv50 of the crosslinked styrene-based organic particles is within the above range, which is beneficial to the separator film having good heat resistance and air permeability.

[0296] The present disclosure provides a crosslinked styrene-based organic particle, which has no melting point. The present disclosure also provides a method for preparing the crosslinked styrene-based organic particle.

[0297] The method for preparing the crosslinked styrene-based organic particle includes the following steps: providing a pre-emulsion containing monomers, a crosslinking agent, an emulsifier, an initiator, and water, and performing emulsion polymerization of the pre-emulsion under heating, inert gas protection, and stirring conditions to obtain the crosslinked styrene-based organic particle. The monomers include one or more of styrene and its derivatives. The mass fraction of the crosslinking agent is 5%-40% based on the total mass of the monomers and the crosslinking agent being 100%.

[0298] The mass fraction of the crosslinking agent is within the above range, which can obtain the crosslinked styrene-based organic particle having good heat resistance and no melting point below 300°C.

[0299] The mass fraction of the crosslinking agent can be 5-40%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, or a range formed by any of the above values, based on the total mass of the monomer and the crosslinking agent being 100%.

[0300] Optionally, the mass fraction of the crosslinking agent can be 6-40%, 8-40%, 8-30%, based on the total mass of the monomer and the crosslinking agent being 100%.

[0301] In some embodiments, the emulsion polymerization reaction can include the steps of: adding the pre-emulsion into a reactor containing water under the conditions of a first temperature, inert gas protection and stirring, and after a first time, heating to a second temperature for a second time to obtain the crosslinked styrene-based organic particles.

[0302] In some embodiments, the first temperature can be 55-70°C.

[0303] In some embodiments, the first time can be 3-6h.

[0304] In some embodiments, the second temperature can be 75-90°C, for example, 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, or a range formed by any of the above values.

[0305] In some embodiments, the second time can be 1-4.5h, for example, 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, 4.5h, or a range formed by any of the above values.

[0306] In some embodiments, the monomer can include one or more of styrene, 1-methyl-1-phenylethylene, 4-methylphenylethylene, 2-methylphenylethylene, 2,4-dimethylphenylethylene, 2,5-dimethylphenylethylene.

[0307] The crosslinking agent forms a crosslinking structural unit of the crosslinked styrene-based organic particles after polymerization with the monomer.

[0308] In some embodiments, the 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.

[0309] Optionally, the crosslinking agent can include one or more of divinylbenzene, N,N-methylenebisacrylamide, N,N'-vinylbisacrylamide.

[0310] In some embodiments, the emulsifier can include, but is not limited to, one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, fatty acid sorbitan, polysorbate, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, polyoxyethylene ether emulsifier, cellulose and its derivatives.

[0311] Optionally, the polyoxyethylene ether emulsifier can include OP-type emulsifiers such as OP-4, OP-7, OP-10, OP-15, OP-20, etc.

[0312] In some embodiments, the mass fraction of the emulsifier can be 0.1%-4% based on 100% of the total mass of the monomer and the crosslinking agent.

[0313] In some embodiments, the initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisdimethylaminoformamide hydrochloride, azobisdimethylaminoformamide hydrochloride, azobisdimethylaminoformamide.

[0314] [Silicon-containing organic crosslinking resin particles]

[0315] In some embodiments, the silicon-containing organic crosslinking resin particles contain a benzene ring structure.

[0316] At present, existing silicon resins are mainly formed by hydrolysis of hydrolyzable siloxanes to form a prepolymer, and then cured to obtain, and have 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 enable the silicon-containing organic crosslinking resin particles to 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 film, a force that resists the shrinkage of the porous base film can be better generated, thereby the heat shrinkage of the whole separator film can be improved, the heat resistance of the separator film can be improved, and the reliability of the secondary battery cell can be improved.

[0317] In some embodiments, the silicon-containing organic crosslinked 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.

[0318] In some embodiments, the silicon-containing organic crosslinked resin particles include crosslinking structure units, and the crosslinking structure units can include divinylbenzene structure units.

[0319] Alternatively, the crosslinking structure units can include one or more of divinylbenzene structure units and diethylene glycol divinyl ether structure units, triethylene glycol divinyl ether structure units, diallyl maleate structure units, ethylene glycol dimethacrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethyladipoyl bis[2-ethylaziridine] structure units, 1,1-nonanedioyl bis[2-methylaziridine] structure units, 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tris(3-aziridinyl) propionate structure units.

[0320] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles can be 80 nm-800 nm.

[0321] The volume distribution particle size Dv50 of the silicon-containing organic crosslinked resin particles in the above range is beneficial to the porous coating of the separation membrane having good heat resistance and air permeability.

[0322] In some embodiments, the cyclic voltammogram of the silicon-containing organic crosslinked resin particles in the first cycle has no oxidation peak in the voltage range of 2.5 V to 4.4 V.

[0323] In some embodiments, the silicon-containing organic crosslinked 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.

[0324] 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.

[0325] In some embodiments, the silicon-containing organic crosslinked resin particles have no melting point.

[0326] In some embodiments, the silicon-containing organic crosslinked resin particles have no glass transition temperature.

[0327] The silicon-containing organic crosslinked resin particles have no glass transition temperature, which indicates that the particles have good heat resistance and thermal stability, and thus can better resist thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0328] In some embodiments, the silicon-containing organic crosslinked resin particles have an initial thermal weight loss temperature T 3d may be 240-330°C.

[0329] The silicon-containing organic crosslinked resin particles have an initial thermal weight loss temperature T 3d which indicates that the particles have good 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.

[0330] The present disclosure provides a silicon-containing organic crosslinked resin particle that has no melting point. The present disclosure also provides a method for preparing the silicon-containing organic crosslinked resin particle.

[0331] The method for preparing the silicon-containing organic crosslinked resin particle includes the following steps: providing a pre-emulsion containing monomers, a crosslinking agent, an emulsifier, an initiator, and water, and performing emulsion polymerization of the pre-emulsion under heating, inert gas protection, and stirring conditions to obtain a slurry containing the silicon-containing organic crosslinked resin particles. The monomers include a silane coupling agent containing an alkenyl group and / or an acryloyloxy group. The mass fraction of the crosslinking agent is 3-18% based on the total mass of the monomers and the crosslinking agent being 100%.

[0332] The monomers include a silane coupling agent containing an alkenyl group and / or an acryloyloxy group, which can initiate the generation of free radicals between the monomers, and thus crosslinking reactions occur between the monomers and the crosslinking agent. Therefore, the silicon-containing organic crosslinked resin particles formed from the monomers and the crosslinking agent of the present disclosure have a three-dimensional network molecular structure, and are not prone to softening or deformation at high temperatures, and thus have high heat resistance.

[0333] The mass fraction of the crosslinking agent is within the above range, and the crosslinked styrene-based organic particles obtained have good heat resistance and no melting point below 300°C.

[0334] The mass fraction of the crosslinking agent is 3-18%, for example, 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 composed of any of the above values.

[0335] Optionally, the mass fraction of the crosslinking agent can be 4-18%, 6-18%, 8-18%, 4-16%, 6-16%, 8-16%, 4-15%, 6-15%, 8-15%, based on the total mass of the monomers and the crosslinking agent being 100%.

[0336] The mass fraction of the crosslinking agent in the above range can obtain the silicon-containing organic crosslinking resin particles with better heat resistance.

[0337] In some embodiments, the method for preparing the silicon-containing organic crosslinking resin particles can further include the step of drying the product obtained from the emulsion polymerization reaction, and then performing a crushing process and a wet grinding process to obtain the slurry containing the silicon-containing organic crosslinking resin particles.

[0338] In other embodiments, the method for preparing the silicon-containing organic crosslinking resin particles can further include the step of drying the product obtained from the emulsion polymerization reaction, and then performing a baking process in an inert gas atmosphere, and then performing a crushing process and a wet grinding process to obtain the slurry containing the silicon-containing organic crosslinking resin particles. In this way, the silicon-containing organic crosslinking resin particles with better heat resistance can be obtained.

[0339] In some embodiments, the drying method for 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.

[0340] In some embodiments, the drying temperature for the product obtained from the emulsion polymerization reaction can be 80-150°C, for example, 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 above values.

[0341] In some embodiments, the drying time for the product obtained from the emulsion polymerization reaction can be 2-12h, for example, 2h, 2.4h, 2.8h, 3.2h, 3.6h, 4h, 4.4h, 4.8h, 5.2h, 5.6h, 6h, 6.4h, 6.8h, 7.2h, 7.6h, 8h, 8.4h, 8.8h, 9.2h, 9.6h, 10h, 10.4h, 10.8h, 11.2h, 11.6h, 12h, or a range consisting of any of the above values.

[0342] The baking is performed in an inert gas atmosphere. In some embodiments, the inert gas can include one or more of nitrogen, argon, and helium.

[0343] 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.

[0344] 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. Optionally, the time of the baking can be 2-8h, 2.4-8h, 3-8h.

[0345] 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.

[0346] 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 optionally a dispersant to obtain a mixed slurry, and then grinding the mixed slurry to obtain a slurry containing silicon-containing organic crosslinked resin particles.

[0347] Optionally, the solvent can comprise one or more of water, methanol, ethanol. More optionally, the solvent can comprise water.

[0348] Optionally, the dispersant can comprise one or more of a polyacrylic acid type dispersant, a carboxymethyl cellulose type dispersant, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone. Optionally, the polyacrylic acid type dispersant can comprise one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, ammonium acrylate. Optionally, the carboxymethyl cellulose type dispersant can comprise one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose.

[0349] Optionally, the grinding medium can comprise one or more of zirconium oxide balls, aluminum oxide balls, silicon nitride balls.

[0350] Optionally, the average particle size of the grinding medium can be 0.1-2mm.

[0351] Optionally, the rotation speed of the grinding can be 500-3000rpm.

[0352] In some embodiments, the emulsion polymerization reaction can include the steps of: dropping the pre-emulsion into a reactor containing water under a first temperature, inert gas protection and stirring conditions, after a first time, the reaction is warmed to a second temperature for a second time to obtain a slurry containing silicon-containing organic crosslinking resin particles.

[0353] In some embodiments, the first temperature can be 55-70 °C.

[0354] In some embodiments, the first time can be 3-6 h.

[0355] In some embodiments, the second temperature can be 72-92 °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 foregoing values.

[0356] In some embodiments, the second time can be 1-5 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 foregoing values.

[0357] 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, helium.

[0358] In some embodiments, the monomer can include a vinyl silane coupling agent and / or an acryloxy silane coupling agent.

[0359] Optionally, the 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-methacryloxypropyltris(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, vinyl dimethyl ethoxysilane, methylvinyl diethoxysilane, vinylmethyl dimethoxysilane, vinylmethyl diethoxysilane, methylvinyl dimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0360] The crosslinking agent forms, after polymerization with the monomer, a crosslinking structure unit of a silicon-containing organic crosslinking resin particle.

[0361] In some embodiments, the crosslinking agent can be a multifunctional crosslinking agent.

[0362] Optionally, the crosslinking agent can include divinylbenzene.

[0363] Optionally, the crosslinking agent can include divinylbenzene and one or more of diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropylene glycol diacrylate, 2,2,4-trimethylhexanedioic acid bis[2-ethylaziridine], 1,1-nonanedioic acid bis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-l-aziridinylpropionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate.

[0364] In some embodiments, the emulsifier can include, but is not limited to, one or more of alkyl sulfate salts, alkyl sulfonate salts, Tween emulsifiers, fatty alcohol polyoxyethylene ethers, fatty alcohol polyoxypropylene ethers, cetyl stearyl alcohol polyethers, oleyl alcohol polyethers. Alternatively, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, laureth-7, laureth-9, laureth-10, oleyl alcohol polyethers-10.

[0365] In some embodiments, the initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutylimidazole hydrochloride, azobisisopropylimidazole.

[0366] In some embodiments, the mass fraction of the initiator can be 0.15%-2.5%, for example, can be 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, or a range consisting of any of the above values, based on 100% of the total mass of the monomer and the crosslinking agent. Alternatively, the mass fraction of the initiator can be 0.3%-2.1%, 0.3%-1.9%, 0.3%-1.7%, 0.3%-1.5%, 0.3%-1.3%.

[0367] In some embodiments, the pre-emulsion can further include a pH adjuster. Alternatively, the pH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia, etc.

[0368] [Non-fluoropolymer binder particles]

[0369] In some embodiments, the glass transition temperature of the non-fluoropolymer binder particles can be 0°C-70°C.

[0370] Alternatively, the non-fluoropolymer binder particles can include a hard monomer, a soft monomer, and a crosslinking monomer.

[0371] Alternatively, the crosslinking monomer can include at least one of a hydroxyl group, a carboxyl group, an ester group, an amide group, a sulfonic acid group, a sulfonate.

[0372] In some embodiments, the hard monomer can include one or more of methyl methacrylate, ethyl methacrylate, styrene, acrylonitrile, methacrylonitrile.

[0373] Alternatively, the hard monomer can include one or both of methyl methacrylate, ethyl methacrylate.

[0374] In some embodiments, the soft monomer can include one or more of ethyl acrylate, n-butyl acrylate, iso-octyl acrylate, octyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, lauryl methacrylate, n-octyl methacrylate.

[0375] In some embodiments, the cross-linking monomer can include one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, diacetone acrylamide, acryloyl ethyl acetoacetate, acrylic acid, methacrylic acid, itaconic acid, styrene sulfonic acid, sodium vinyl sulfonate.

[0376] In other embodiments, the non-fluoropolymer binder particles include a first glass transition temperature T g and a second glass transition temperature T g , and the first glass transition temperature and the second glass transition temperature are different.

[0377] Optionally, the first glass transition temperature T g may be less than or equal to 25°C, and the second glass transition temperature T g may be greater than 25°C.

[0378] More optionally, the first glass transition temperature T g may be from -20°C to 25°C.

[0379] More optionally, the second glass transition temperature T g may be from 26°C to 70°C.

[0380] The non-fluoropolymer binder particles satisfying the above first glass transition temperature T g and the second glass transition temperature T g have no tackiness at a certain temperature, so that the separator film can be conveniently wound and unwound; after being wound with the electrode sheet and then being cold-pressed or hot-pressed, the non-fluoropolymer binder particles can exhibit better adhesion, so that the electrode sheet and the separator film can be closely adhered to each other, the hardness of the electrode assembly is improved, and the cycle performance of the secondary battery cell is improved.

[0381] In some embodiments, the non-fluoropolymer binder particles can include an acrylate copolymer. The acrylate copolymer is a general term for polymers generated by copolymerization of acrylate monomers and other comonomers.

[0382] The acrylate copolymer has good adhesion, and the use of the acrylate copolymer makes the adhesion between the separator film and the electrode sheet after cold-pressing or hot-pressing better.

[0383] In some embodiments, the non-fluoropolymer binder particles can include at least one of an ester group, a carboxyl group, a carbonyl group, an amide group, a nitrile group.

[0384] The ester group can improve the anti-swelling ability of the non-fluoropolymer binder particles, and as a flexible monomer segment in the molecular chain segment, it helps to adjust the glass transition temperature to a suitable range.

[0385] The carboxyl group can form a binding force with the functional groups of the electrode sheet and the separator film, improving the bonding effect.

[0386] The carbonyl group and the amide group are conducive to improving the adhesion of the non-fluoropolymer binder particles.

[0387] The nitrile group helps to improve the ionic conductivity and improve the adhesion of the non-fluoropolymer binder particles.

[0388] In some embodiments, the non-fluoropolymer binder particles can include a first polymer and a second polymer, and the first polymer and the second polymer can each include an acrylate copolymer.

[0389] The non-fluoropolymer binder particles include a first polymer and a second polymer, and it can be understood that the non-fluoropolymer binder particles including the first polymer and the second polymer include a first glass transition temperature and a second glass transition temperature.

[0390] In some embodiments, the mass ratio of the first polymer to the second polymer can be 1:(0.1-10), and optionally 1:(0.5-3).

[0391] The non-fluoropolymer binder particles are secondary particles formed by agglomeration of primary particles of the first polymer and primary particles of the second polymer, and the primary particles of the first polymer and the primary particles of the second polymer each have the opportunity to be exposed on the surface of the secondary particles. By adjusting the mass ratio of the first polymer and the second polymer, the opportunity for the first polymer to be exposed on the surface of the secondary particles can be adjusted to adjust the adhesion of the non-fluoropolymer binder particles.

[0392] The mass ratio of the first polymer to the second polymer within the above range can improve the problem that the non-fluoropolymer binder particles are too soft to affect the performance of the electrode assembly, such as improving the problem that the non-fluoropolymer binder particles may be too soft to cause a hole blocking problem, and improving the problem that the non-fluoropolymer binder particles are too hard to affect the bonding effect between the separator film and the electrode sheet.

[0393] It can be understood that the primary particle size of the polymer latex of the first polymer and the second polymer can be 100 nm-150 nm, the average particle size of the particles after the two kinds of latexes are mixed and spray dried is 6 μm to 15 μm, and the primary particles of the two polymers are mixed together to jointly constitute the secondary particles after spray drying.

[0394] In some embodiments, the first polymer and / or the second polymer includes a first polymerized monomer.

[0395] The structure of the first polymerized monomer includes the following formula, R1 includes a hydrogen atom or an alkyl group of 1-12 carbon atoms, and R2 includes an alkyl group of 1-12 carbon atoms.

[0396] The first polymerized monomer includes an unsaturated ester group, which is conducive to polymerization and can improve the anti-swelling ability of the non-fluoropolymer binder particles, and as a flexible monomer segment in a molecular chain segment, it helps to adjust the glass transition temperature to a suitable range.

[0397] Optionally, the first polymerized monomer can include one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-propyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0398] Using any one or more of the above first polymerized monomers can adjust the glass transition temperature of the non-fluoropolymer binder particles and improve the anti-swelling ability of the non-fluoropolymer binder particles.

[0399] In some embodiments, the first polymer includes a second polymerized monomer, and the structure of the second polymerized monomer includes the following formula, R3 includes a hydrogen atom, a substituted or unsubstituted alkyl group of 1-6 carbon atoms.

[0400] The second polymerized monomer includes an unsaturated carboxyl group, which is conducive to polymerization, and the inclusion of the second polymerized monomer including a carboxyl group in the first polymer can form a binding force with the functional groups of the electrode sheet and the separator film, thereby improving the bonding effect.

[0401] Optionally, the second polymerized monomer can include one or more of acrylic acid, methacrylic acid, butenoic acid, and heptoenoic acid.

[0402] Using any one or more of the above second polymerized monomers can adjust the bonding performance of the first polymer.

[0403] In some embodiments, the first polymer and / or the second polymer includes a third polymeric monomer, the structure of the third polymeric monomer includes the following formula, R4 includes a hydrogen atom or an alkyl group of 1-6 carbon atoms, and R5 includes a hydrogen atom, a hydroxyl-substituted alkyl group of 1-6 carbon atoms, or an alkoxy group of 1-6 carbon atoms.

[0404] The third polymeric monomer includes an unsaturated amide group, which facilitates polymerization of the monomer, and the monomer functions to adjust the molecular weight while also providing good adhesion.

[0405] Optionally, the third polymeric monomer can include one or more of acrylamide, N- hydroxymethyl acrylamide, and N-butoxymethyl acrylamide.

[0406] The use of any one or more of the above-described third polymeric monomers can function to adjust the molecular weight, which is within a range that helps to improve adhesion.

[0407] In some embodiments, the second polymer includes a fourth polymeric monomer, the structure of the fourth polymeric monomer includes the following formula, and R6 includes a hydrogen atom or an alkyl group of 1-6 carbon atoms.

[0408] The fourth polymeric monomer includes an unsaturated cyano group, which facilitates polymerization, helps to improve ionic conductivity, and improves adhesion.

[0409] Optionally, the fourth polymeric monomer can include one or more of acrylonitrile and methacrylonitrile.

[0410] The use of any one or more of the above-described fourth polymeric monomers can improve ionic conductivity of the non-fluoropolymer binder particles.

[0411] The non-fluoropolymer binder particles prepared by using the above-mentioned polymerization monomers can have good adhesion. It can be understood that the non-fluoropolymer binder particles include a first polymer and a second polymer. The first polymer is prepared by emulsion polymerization of at least two of the first polymerization monomer, the second polymerization monomer and the third polymerization monomer. It can be understood that the first polymer has better performance when it is composed of the above-mentioned three monomers. The second polymer emulsion is prepared by emulsion polymerization of at least two of the first polymerization monomer, the third polymerization monomer and the fourth polymerization monomer. It can be understood that the second polymer has better performance when it is composed of the above-mentioned three monomers. The first polymer and the second polymer prepared by using the above-mentioned polymerization monomers have a suitable glass transition temperature. In the porous coating of the separator film, the non-fluoropolymer binder particles can not only meet the requirement of no adhesion at room temperature, but also meet the requirement of improving the adhesion between the separator film and the electrode sheet during cold pressing or hot pressing, thereby improving the hardness of the electrode assembly and the cycle performance of the secondary battery cell.

[0412] The preparation method of the non-fluoropolymer binder particles can include the following steps: mixing and stirring water, an emulsifier, an initiator and monomers for preparing the first polymer, heating and reacting to obtain a first polymer emulsion; mixing and stirring water, an emulsifier, an initiator and monomers for preparing the second polymer, heating and reacting to obtain a second polymer emulsion; mixing and stirring the first polymer emulsion and the second polymer emulsion, and then spray drying to obtain the non-fluoropolymer binder particles.

[0413] In some embodiments, the thickness of the porous coating can be 0.5 μm-5 μm. The thickness of the porous coating refers to the thickness of the porous coating on one side of the porous base film, and the thickness of the porous coating refers to the thickness of the part of the porous coating without protruding non-fluoropolymer binder particles.

[0414] Optionally, the thickness of the porous coating can be 0.5 μm-4 μm, 0.5 μm-3 μm, 0.5 μm-2 μm, 0.8 μm-4 μm, 0.8 μm-3 μm, 0.8 μm-2 μm.

[0415] In some embodiments, the porous base film can include a film or a non-woven web selected from any one or at least two of the following: 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, polyvinyl naphthalene.

[0416] 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.

[0417] In some embodiments, the porous base film can have a thickness of 4-12 μm, optionally 4-9 μm.

[0418] In some embodiments, the porous base film can have a porosity of 25-60%, optionally 28-50%.

[0419] In some embodiments, the ratio of the volume distribution particle size Dv50 of the heat-resistant organic particles to the average pore size of the porous base film can be greater than or equal to 1.1. This can reduce the problem of pore blocking and improve the air permeability and ion conductivity of the separator film.

[0420] In some embodiments, the porous base film can have an average pore size of 25-82 nm.

[0421] In some embodiments, the separator film can have a thickness of 5-14 μm, optionally 5-12 μm, 6-12 μm. This is beneficial for improving the energy density of the secondary battery cell.

[0422] It should be noted that the porous coating parameters of the separator film described above are the porous coating parameters of one side of the porous base film. When the porous coating is provided on both sides of the porous base film, as long as the porous coating parameters of any one side meet the present disclosure, it is considered to fall within the protection scope of the present disclosure.

[0423] The present disclosure also provides a method for preparing the separator film described above.

[0424] The method for preparing the separator film comprises the following steps: providing a porous base film; providing a slurry comprising heat-resistant organic particles, non-fluoropolymer binder particles and a binder; coating the slurry on at least one surface of the porous base film, drying to form a porous coating, and obtaining a separator film. The non-fluoropolymer binder particles are embedded in the heat-resistant organic particles and form protrusions on the surface of the porous coating.

[0425] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0426] In some embodiments, the slurry can further comprise other components, for example, it can further comprise dispersants, wetting agents, etc.

[0427] Some raw materials and their content, etc. used in the method for preparing the separator film can refer to the separator film described above, which will not be repeated here.

[0428] If not specifically stated, each raw material used in the method for preparing the separator film can be obtained by commercial purchase.

[0429] The present disclosure also provides another method for preparing the separator film described above.

[0430] The method for preparing the separator film includes the following steps: providing a porous base film; providing a heat-resistant layer slurry including heat-resistant organic particles and a first binder and a bonding layer slurry including non-fluoropolymer binder particles and a second binder; coating the heat-resistant layer slurry on at least one surface of the porous base film to form a heat-resistant layer after drying; coating the bonding layer slurry on at least a part of the surface of the heat-resistant layer or the porous base film to form a bonding layer after drying, and obtaining the separator film. The porous coating layer of the separator film includes the heat-resistant layer and the bonding layer, the bonding layer is arranged on at least a part of the surface of the heat-resistant layer or the porous base film, the heat-resistant organic particles are arranged in the heat-resistant layer, and the non-fluoropolymer binder particles are arranged in the bonding layer.

[0431] In some embodiments, the solvent of the heat-resistant layer slurry and the bonding layer slurry can be water, for example, deionized water.

[0432] In some embodiments, the heat-resistant layer slurry can further include other components, for example, can further include dispersants, wetting agents, etc.

[0433] In some embodiments, the bonding layer slurry can further include other components, for example, can further include dispersants, wetting agents, etc.

[0434] Some raw materials used in the method for preparing the separator film and their content and other parameters can refer to the separator film described above, which will not be described here.

[0435] If not specifically stated, each raw material used in the method for preparing the separator film can be obtained by purchase.

[0436] The embodiments of the present disclosure further provide a secondary battery cell. The secondary battery cell includes the separator film provided by the embodiments of the present disclosure.

[0437] The secondary battery cell further includes a positive electrode sheet, a negative electrode sheet, and an electrolyte.

[0438] The secondary battery cell provided by the present disclosure can include but is not limited to a lithium secondary battery cell, a sodium secondary battery cell, etc., and the composition of the positive electrode sheet, the negative electrode sheet, and the electrolyte will be different for different types of secondary battery cells.

[0439] [Positive electrode sheet]

[0440] In some embodiments, the positive electrode sheet can include a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite in the thickness direction of the positive electrode current collector, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0441] LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi0.8Co0.15Al0.05O2, LiNi0.8Co0.15Mn0.05O2, LiNi0.5Co0.2Mn0.3O2, LiNi0.5Mn1.5O2, LiNi0.5Ti0.5O2, LiV6O13, and modified compounds of each of the above. In some embodiments, to further enhance the energy density of the secondary battery cell, the positive active material can include one or more of lithium transition metal oxides and modified compounds thereof of the general formula Li a Ni b Co c M d O e A f 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.

[0442] As an example, the positive active material can include but is not limited to one or more of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi0.8Co0.15Al0.05O2, LiNi0.8Co0.15Mn0.05O2, LiNi0.5Co0.2Mn0.3O2, LiNi0.5Mn1.5O2, LiNi0.5Ti0.5O2, LiV6O13, and modified compounds of each of the above. 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.

[0443] 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 list of positive active materials 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 list of positive active materials 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.

[0444] Taking a sodium secondary 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.), and prussian blue 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 materials, and materials of the general formula X p M’ q (PO4) r O x Y 3-x . In the general formula X p M’ q (PO4) r O x Y 3-x , 0 < p < 4, 0 < q < 2, 1 < r < 3, 0 < x < 2, X includes but is not limited to one or more of H + , Li + , Na + , K + and NH4 + , M’ is a transition metal cation, which can optionally include but is not limited to one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, which can optionally be one or more of F, Cl and Br.

[0445] The modified compounds of the positive active materials of the above lithium secondary battery cell and sodium secondary battery cell can be doping modification and / or surface coating modification of the positive active material.

[0446] In some embodiments, the positive electrode film layer can further include a positive electrode conductive agent. As an example, the positive electrode conductive agent can include, but is not limited to, one or more of super-P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0447] In some embodiments, the positive electrode film layer can further include a positive electrode binder. As an example, the positive electrode binder can include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic resin.

[0448] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. As an example of a metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0449] 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.

[0450] [Negative electrode tab]

[0451] In some embodiments, the negative electrode tab can include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite in the thickness direction of itself, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0452] The negative electrode active material can employ a material known in the art that can be used for a secondary battery cell. As an example, the negative electrode active material can include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material can include, but is not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and 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.

[0453] In some embodiments, the negative electrode film layer can further include a negative electrode conductive agent. As an example, the negative electrode conductive agent can include, but is not limited to, one or more of super-P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0454] In some embodiments, the negative electrode film layer can further include a negative electrode binder. As an example, the negative electrode binder can include, but is not limited to, one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0455] In some embodiments, the negative electrode film layer can further include other auxiliary agents. As an example, the other auxiliary agents can include thickening agents, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0456] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0457] The negative electrode film layer is typically formed by coating a negative electrode slurry on a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing and uniformly stirring a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and other optional auxiliary agents in a solvent. The solvent can be N-methyl pyrrolidone (NMP) or deionized water, but is not limited thereto.

[0458] The negative electrode tab does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode tab further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) interposed between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0459] In some embodiments, the negative electrode tab can use a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, or the like. When the foamed metal is used as the negative electrode tab, the surface of the foamed metal can not be provided with a negative electrode active material, or of course can be provided with a negative electrode active material.

[0460] [Electrolyte]

[0461] The electrolyte functions to conduct ions between the positive electrode and the negative electrode.

[0462] In some embodiments, the electrolyte employs an electrolytic solution including an electrolyte salt and an organic solvent.

[0463] Taking a lithium secondary battery cell as an example, the electrolyte salt can include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bisoxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0464] Taking a sodium secondary battery cell as an example, 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 difluorooxalate borate (NaDFOB), sodium bisoxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0465] 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.

[0466] In some embodiments, the electrolyte can further include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain performance of the secondary battery cell, such as an additive capable of improving overcharge performance, an additive capable of improving high-temperature performance, an additive capable of improving low-temperature performance, and the like.

[0467] Optionally, the additive can include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), and vinyl sulfate (DTD).

[0468] Methods for preparing 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 through a winding process, the electrode assembly can be placed in an outer package, and the electrolyte described above can be injected after drying. The secondary battery cell can be obtained after processes such as standing and formation.

[0469] Embodiments

[0470] 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 herein are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used without further purification, and the instruments used in the examples are commercially available.

[0471] Example 1-1

[0472] Preparation of heat-resistant organic particles

[0473] 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 130°C, and the temperature was maintained for 3 h. After the end of the first curing, the temperature of the curing oven was increased to 245°C, and the temperature was maintained for 4 h. After the end of the second curing, the cured resol resin material was removed, allowed to cool naturally in air, and then crushed, wet-milled, sieved, and wet-magnetized to obtain a resol resin-based organic particle 1# slurry.

[0474] The resol resin-based organic particle 1# satisfies the following characteristics: it is a thermosetting resol resin, has no melting point, and has no glass transition temperature T g .

[0475] Preparation of non-fluoropolymer binder particles

[0476] According to the mass ratio of three monomers 90:5:5, methyl acrylate, acrylic acid and acrylamide were weighed and mixed uniformly. In a 5000 mL four-necked flask equipped with mechanical stirring, thermometer and condenser, 1000 g of mixed monomers, 30 g of sodium dodecyl sulfate emulsifier, 10 g of ammonium persulfate initiator, 1200 g of deionized water were added, and emulsified at high speed for 30 min. Under nitrogen protection, the temperature was raised to 75°C for 4h, then cooled to below 40°C, adjusted to neutral pH, and the filtrate was obtained. The first polymer emulsion A1 was obtained.

[0477] According to the mass ratio of three monomers 80:10:10, n-butyl methacrylate, N-hydroxymethyl acrylamide and methacrylonitrile were weighed and mixed uniformly. In a 1000 mL four-necked flask equipped with mechanical stirring, thermometer and condenser, 200 g of mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, 300 g of deionized water were added, and emulsified at high speed for 30 min. Under nitrogen protection, the temperature was raised to 75°C for 4h, then cooled to below 40°C, adjusted to neutral pH, and the filtrate was obtained. The second polymer emulsion B1 was obtained.

[0478] According to the mass percentage of the first polymer and the second polymer 1:1, the first polymer emulsion A1 and the second polymer emulsion B2 were weighed and mixed uniformly, and then the non-fluoropolymer binder particles were obtained by spray drying process.

[0479] The non-fluoropolymer binder particles include a first glass transition temperature T g and a second glass transition temperature T g , the first glass transition temperature T g is 16.9°C, and the second glass transition temperature T g is 46.5°C.

[0480] Preparation of the isolation film

[0481] The phenolic resin organic particles 1# slurry, the dispersant carboxymethyl cellulose sodium, and the binder polyacrylate were mixed uniformly in deionized water in proportion to obtain a heat-resistant layer slurry. The solid mass ratio of phenolic resin organic particles, dispersant carboxymethyl cellulose sodium and binder polyacrylate in the heat-resistant layer slurry was 90:2:8.

[0482] The non-fluoropolymer binder particles, the binder polyacrylate, the dispersant carboxymethyl cellulose sodium and the ether-based surfactant obtained above were stirred uniformly in deionized water in a solid mass ratio of 87:8:3:2 to obtain a bonding layer slurry.

[0483] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The prepared 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 processes, the separator film was obtained.

[0484] Preparation of a secondary battery cell

[0485] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, the positive electrode binder polyvinylidene fluoride (PVDF) were added to N-methyl pyrrolidone (NMP) at a mass ratio of 97:2:1, and after being fully stirred and mixed uniformly, an anode slurry was prepared; the anode slurry was uniformly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slitted to obtain the positive electrode sheet.

[0486] The negative electrode active material artificial graphite, the negative electrode conductive agent acetylene black, the negative electrode binder styrene-butadiene rubber (SBR), and the thickening agent sodium carboxymethyl cellulose were added to deionized water at a mass ratio of 96.0:1.5:1.5:1, and after being fully stirred and mixed uniformly, a negative electrode slurry was prepared; the negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and then dried, cold-pressed, and slitted to obtain the negative electrode sheet.

[0487] At 25°C, ethylene carbonate (EC) and methyl ethyl carbonate (EMC) were mixed at a volume ratio of 3:7 to obtain a mixed solvent, and then LiPF6, vinylene carbonate (VC), and vinyl sulfate (DTD) were dissolved in the mixed solvent to obtain an electrolyte. The concentration of LiPF6 was 1 mol / L. The mass fraction of VC was 2%, and the mass fraction of DTD was 3%, based on the mass of the electrolyte.

[0488] The positive electrode sheet, the separator film, and the negative electrode sheet were stacked and wound in order, and then hot-pressed to form an electrode assembly; the electrode assembly was placed in a hard-shell outer package, and the electrolyte prepared above was added. After standing, formation, and other processes, a secondary battery cell was obtained.

[0489] Example 1-2

[0490] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0491] Preparation of a separator film

[0492] The phenolic resin organic particle 1# slurry, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate were stirred and mixed uniformly in deionized water to obtain a porous coating slurry. The solid mass ratio of phenolic resin organic particle 1#, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate in the porous coating slurry was 80:10:2:8.

[0493] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The prepared porous coating slurry was coated on both surfaces of the porous base film by microgravure coating, and then dried and slitted to obtain the separator film.

[0494] Examples 1-3

[0495] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0496] Preparation of non-fluoropolymer binder particles

[0497] According to the mass ratio of the three monomers 80:10:10, n-butyl methacrylate, N-hydroxymethyl acrylamide, and methacrylonitrile were weighed and mixed uniformly. In a 1000 mL four-necked flask equipped with mechanical stirring, thermometer, and condenser, 200 g of mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added. The mixture was emulsified at high speed for 30 min. Under nitrogen protection, the temperature was raised to 75°C and reacted for 4 h. Then the temperature was lowered to below 40°C, the pH was adjusted to neutral, and the product was filtered out to obtain a polymer emulsion. The polymer emulsion was diluted and then spray dried to obtain non-fluoropolymer binder particles. The glass transition temperature T g of the non-fluoropolymer binder particles was 46.5°C.

[0498] Comparative Example 1-1

[0499] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0500] Preparation of heat-resistant organic particles

[0501] A commercially available phenol and formaldehyde-based resol resin material was placed in a curing furnace, the atmosphere was set to air, and the temperature was set to 350°C. The temperature was maintained for 4 h. After the curing was completed, the cured phenolic resin material was taken out, naturally cooled in air, and then crushed, wet ground, sieved, and wet demagnetized to obtain a phenolic resin organic particle D1# slurry.

[0502] Preparation of the separator film

[0503] The phenolic resin organic particles D1# slurry, dispersant sodium carboxymethyl cellulose, and binder polyacrylate were mixed evenly in deionized water in a certain proportion to obtain the heat-resistant layer slurry. The solid mass ratio of the phenolic resin organic particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate in the heat-resistant layer slurry was 90:2:8.

[0504] Commercially available polyvinylidene fluoride granules, adhesive polyacrylate, dispersant sodium carboxymethyl cellulose, and ether-based surfactants were mixed evenly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain the adhesive layer slurry.

[0505] A commercially available 7μm thick polyethylene microporous film was used as the porous base film. The prepared heat-resistant layer slurry was coated onto the two surfaces of the porous base film using a microgravure method. After drying, the adhesive layer slurry was sprayed onto the heat-resistant layer. Then, through drying and slitting processes, the release film was obtained.

[0506] Performance testing

[0507] (1) Thermal shrinkage rate test of the separator film

[0508] The heat shrinkage rate test of the release liner can be referenced in GB / T 36363-2018.

[0509] Cut the release film into samples with a width of 50mm and a length of 100mm using a punching machine. Take 5 parallel samples and place them on A4 paper. Then place the A4 paper containing the samples on corrugated paper with a thickness of 1mm to 5mm.

[0510] Set the temperature of the forced-air drying oven to 130℃. After the temperature reaches the set temperature and stabilizes for 60 minutes, place the A4 paper placed on the corrugated paper into the forced-air drying oven and start timing. After the set time (1 hour in this disclosure) is reached, measure the length and width of the isolation film, and mark the values ​​as a and b respectively.

[0511] Calculation of heat shrinkage rate: Longitudinal (MD) heat shrinkage rate = [(100-a) / 100]×100%, Transverse (TD) heat shrinkage rate = [(50-b) / 50]×100%, take the average value of 3 parallel samples as the test result.

[0512] (2) Cycle performance test of secondary battery cells

[0513] The secondary battery monomer was charged at 60°C at 1 / 3C constant current to 4.25V, then charged at 4.25V constant voltage to a current of 0.05C, rested for 5 min, then discharged at 1 / 3C constant current to 2.8V, and the obtained discharge capacity was recorded as the initial capacity C0; the above charging and discharging steps were repeated, and the discharge capacity Cn of the secondary battery monomer after the nth cycle was recorded at the same time, then the capacity retention rate Pn of the secondary battery monomer after each cycle was (Cn / C0) x 100%. The capacity retention rate of the secondary battery monomer after 500 cycles can reflect the difference in cycle performance of the secondary battery monomer.

[0514] Table 1

[0515] From the above test results, it can be seen that the separator film of the present disclosure has good heat resistance, which can make the secondary battery monomer have good cycle performance.

[0516] Example 2-1

[0517] The preparation process of the secondary battery monomer was the same as that of Example 1-1, except for the following differences.

[0518] Preparation of heat-resistant organic particles

[0519] Commercially available melamine formaldehyde resin particles were cured in an air atmosphere at 285°C for 3.5h, and then subjected to crushing, wet sanding, sieving, and wet magnetic removal to obtain a slurry of polymer particles 1# containing triazine ring structure units. The molar ratio of raw materials formaldehyde to melamine in the melamine formaldehyde resin was 2.5:1.

[0520] The polymer particles 1# containing triazine ring structure units satisfy the following characteristics: no melting point, and no glass transition temperature T g .

[0521] Example 2-2

[0522] The preparation process of the secondary battery monomer was the same as that of Example 2-1, except for the following differences.

[0523] Preparation of the separator film

[0524] The slurry of polymer particles 1# containing triazine ring structure units, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate were mixed uniformly in deionized water in proportion to obtain a porous coating slurry. The solid mass ratio of polymer particles 1# containing triazine ring structure units, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate in the porous coating slurry was 80:10:2:8.

[0525] A commercially available polyethylene microporous film having a thickness of 7 μm was used as the porous base film. The prepared porous coating slurry was applied to both surfaces of the porous base film by microgravure coating, and then dried and slit to obtain the separator.

[0526] Example 2-3

[0527] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0528] Preparation of heat-resistant organic particles

[0529] Commercially available melamine formaldehyde resin particles were cured in an air atmosphere at 285°C for 3.5 h, and then subjected to crushing, wet sanding, sieving, and wet magnetic removal to obtain a slurry of polymer particles 1# containing a triazine ring structural unit. The raw material formaldehyde and melamine in the melamine formaldehyde resin had a molar ratio of 2.5:1.

[0530] The polymer particles 1# containing a triazine ring structural unit satisfied the following characteristics: no melting point, and no glass transition temperature T g .

[0531] Preparation of non-fluoropolymer binder particles

[0532] N-butyl methacrylate, N-methylol acrylamide, and methacrylonitrile were weighed out in a mass ratio of 80:10:10, respectively, and mixed uniformly. A 1000 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser tube was charged with 200 g of the mixed monomers, 6 g of a sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water, and the mixture was emulsified at high speed for 30 min. After the temperature was raised to 75°C under nitrogen protection and the reaction was performed for 4 h, the temperature was lowered to below 40°C, the pH was adjusted to neutral, and the product was filtered to obtain a polymer emulsion. The polymer emulsion was diluted and then subjected to a spray drying process to obtain non-fluoropolymer binder particles. The non-fluoropolymer binder particles had a glass transition temperature T g of 46.5°C.

[0533] Comparative Example 2-1

[0534] The preparation process of the secondary battery cell was the same as that of Comparative Example 1-1, except for the following differences.

[0535] Preparation of heat-resistant organic particles

[0536] Commercially available melamine formaldehyde resin particles were subjected to crushing, wet sanding, sieving, and wet magnetic removal to obtain a slurry of polymer particles D1# containing a triazine ring structural unit. The raw material formaldehyde and melamine in the melamine formaldehyde resin had a molar ratio of 2.5:1.

[0537] Table 2

[0538] From the above test results, it can be seen that the separator film of the present disclosure has good heat resistance, and can make the secondary battery monomer have good cycle performance.

[0539] Example 3-1

[0540] The preparation process of the secondary battery monomer is the same as that of Example 1-1, except for the following differences.

[0541] Preparation of heat-resistant organic particles

[0542] A pre-emulsion was prepared by emulsifying 0.8 g of sodium dodecyl sulfate, 80 mg of sodium persulfate, 20 ml of deionized water, 27.5 g of styrene, and 12.5 g of divinylbenzene. 140 g of deionized water was added to the reactor and heated to 65°C. Under the conditions of nitrogen protection and stirring, the above-mentioned pre-emulsion was added dropwise, and after reaction for 4 h, the temperature was raised to 72°C for curing reaction for 2.5 h, to obtain a cross-linked styrene-based organic particle 1# emulsion.

[0543] The cross-linked styrene-based organic particle 1# meets the following characteristics: no melting point, glass transition temperature T g between 110°C and 165°C.

[0544] Example 3-2

[0545] The preparation process of the secondary battery monomer is the same as that of Example 3-1, except for the following differences.

[0546] Preparation of the separator film

[0547] The cross-linked styrene-based organic particle 1# slurry, non-fluoropolymer binder particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate were mixed uniformly in deionized water in a proportion to obtain a porous coating slurry. The solid mass ratio of the cross-linked styrene-based organic particle 1#, non-fluoropolymer binder particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate in the porous coating slurry was 80:10:2:8.

[0548] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The prepared porous coating slurry was coated on both surfaces of the porous base film by micro-gravure method, and then dried and slitted to obtain a separator film.

[0549] Example 3-3

[0550] The preparation process of the secondary battery monomer is the same as that of Example 1-1, except for the following differences.

[0551] Preparation of heat-resistant organic particles

[0552] A pre-emulsion was prepared by emulsifying 0.8 g of sodium dodecyl sulfate, 80 mg of sodium persulfate, 20 ml of deionized water, 27.5 g of styrene, and 12.5 g of divinylbenzene. 140 g of deionized water was added to a reactor, which was heated to 65°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was increased to 72°C for 2.5 h of curing reaction to obtain a cross-linked styrene-based organic particle 1# emulsion.

[0553] The cross-linked styrene-based organic particle 1# satisfies the following characteristics: no melting point, a glass transition temperature T g between 110°C and 165°C.

[0554] Preparation of non-fluoropolymer binder particles

[0555] According to a mass ratio of 80:10:10 of the three monomers, n-butyl methacrylate, N-hydroxymethyl acrylamide, and methacrylonitrile were weighed and mixed uniformly. In a 1000 mL four-necked flask equipped with mechanical stirring, a thermometer, and a condenser, 200 g of mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added. The mixture was emulsified at high speed for 30 min. Under nitrogen protection, the temperature was increased to 75°C for 4 h of reaction, then decreased to below 40°C, the pH was adjusted to neutral, and the product was filtered to obtain a polymer emulsion. The polymer emulsion was diluted and then non-fluoropolymer binder particles were obtained by spray drying process. The glass transition temperature T g of the non-fluoropolymer binder particles was 46.5°C.

[0556] Comparative Example 3-1

[0557] The preparation process of the secondary battery cell was the same as that of Comparative Example 1-1, except for the following differences.

[0558] Preparation of heat-resistant organic particles

[0559] A pre-emulsion was prepared by emulsifying 0.8 g of sodium dodecyl sulfate, 80 mg of sodium persulfate, 20 ml of deionized water, 39.5 g of styrene, and 0.5 g of divinylbenzene. 140 g of deionized water was added to a reactor, which was heated to 65°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was increased to 72°C for 2.5 h of curing reaction to obtain a cross-linked styrene-based organic particle D1# emulsion.

[0560] Table 3

[0561] From the above test results, it can be seen that the isolation film of the present disclosure has good heat resistance, and can make the secondary battery cell have good cycle performance.

[0562] Example 4-1

[0563] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0564] Preparation of heat-resistant organic particles

[0565] A pre-emulsion was prepared by emulsifying 0.42 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 51.6 g of 3-(acryloxy)propyl trimethoxysilane, 3 g of γ-methacryloxypropyl triisopropoxysilane, and 5.4 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 82°C for 1.4 h of curing reaction, and a silicon-containing organic crosslinked resin particle 1# emulsion was obtained.

[0566] The silicon-containing organic crosslinked resin particle 1# satisfies the following characteristics: the silicon-containing organic crosslinked resin particle is a network structure formed with a carbon-carbon bond as the main chain, and the side chain contains a siloxane structure. It has no melting point, and no glass transition temperature T g .

[0567] Example 4-2

[0568] The preparation process of the secondary battery cell was the same as that of Example 4-1, except for the following differences.

[0569] Preparation of separator film

[0570] The silicon-containing organic crosslinked resin particle 1# slurry, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate were mixed uniformly in deionized water in proportion to obtain a porous coating slurry. The solid mass ratio of the silicon-containing organic crosslinked resin particle 1#, non-fluoropolymer binder particles, dispersant carboxymethyl cellulose sodium, and binder polyacrylate in the porous coating slurry was 80:10:2:8.

[0571] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The prepared porous coating slurry was coated on both surfaces of the porous base film by microgravure method, and then dried and slitted to obtain a separator film.

[0572] Example 4-3

[0573] The preparation process of the secondary battery cell was the same as that of Example 1-1, except for the following differences.

[0574] Preparation of heat-resistant organic particles

[0575] A pre-emulsion was prepared by emulsifying 0.42 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 51.6 g of 3-(acryloxy)propyltrimethoxysilane, 3 g of γ-methacryloxypropyltriisopropoxysilane, and 5.4 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 82°C for 1.4 h of curing reaction, and a silicon-containing organic crosslinked resin particle 1# emulsion was obtained.

[0576] The silicon-containing organic crosslinked resin particle 1# satisfies the following characteristics: the silicon-containing organic crosslinked resin particle is a network structure formed with a carbon-carbon bond as a main chain, and a side chain containing a siloxane structure, which has no melting point and no glass transition temperature T g .

[0577] Preparation of non-fluoropolymer binder particles

[0578] According to a mass ratio of 80:10:10 of the three monomers, n-butyl methacrylate, N-hydroxymethyl acrylamide, and methacrylonitrile were weighed and mixed uniformly. A 1000 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser was charged with 200 g of the mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water. The mixture was emulsified at high speed for 30 min. Under nitrogen protection, the temperature was raised to 75°C for 4 h of reaction, and then the temperature was lowered to below 40°C. The pH was adjusted to neutral, and the filtrate was obtained. After dilution, the polymer emulsion was obtained by a spray drying process to obtain non-fluoropolymer binder particles. The glass transition temperature T g of the non-fluoropolymer binder particles was 46.5°C.

[0579] Comparative Example 4-1

[0580] The preparation process of the secondary battery cell was the same as that of Comparative Example 1-1, except for the following differences.

[0581] Preparation of heat-resistant organic particles

[0582] A pre-emulsion was prepared by emulsifying 0.42 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 60 g of 3-(acryloxy)propyltrimethoxysilane. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 82°C for 1.4 h of curing reaction, and a silicon-containing organic crosslinked resin particle D1# emulsion was obtained.

[0583] Table 4

[0584] From the test results, it can be seen that the isolation film of the present disclosure has good heat resistance, and can make the secondary battery monomer have good cycle performance.

[0585] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned 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 in the technical scope of the present disclosure. In addition, within the scope of the main idea of the present disclosure, various modifications that can be thought of by those skilled in the art are applied to the embodiments, and other ways constructed by combining part of the constituent elements in the embodiments are also included in the scope of the present disclosure.

Claims

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 layer comprises heat-resistant organic particles and non-fluoropolymer binder particles. The separator film according to claim 1, wherein The non-fluoropolymer binder particles are embedded in the heat-resistant organic particles and form protrusions on the surface of the porous coating layer. The isolation film according to claim 2, wherein The mass content of the heat-resistant organic particles in the porous coating layer is 68%-92%; and / or The mass content of the non-fluoropolymer binder particles in the porous coating layer is 5%-30%. The separator film according to any one of claims 2-3, wherein, The porous coating layer further comprises fluoropolymer binder particles; Optionally, the mass content of the non-fluoropolymer binder particles in the porous coating layer is greater than the mass content of the fluoropolymer binder particles in the porous coating layer; Optionally, the particle size of the fluoropolymer binder particles is greater than the particle size of the non-fluoropolymer binder particles; Optionally, the fluoropolymer binder particles comprise aggregates of primary particles. The separator film according to claim 1, wherein The porous coating layer comprises a heat-resistant layer and a bonding layer, the bonding layer is arranged on at least a part of the surface of the heat-resistant layer or the porous base film, the heat-resistant organic particles are arranged in the heat-resistant layer, and the non-fluoropolymer binder particles are arranged in the bonding layer. The isolation film according to claim 5, wherein The mass content of the heat-resistant organic particles in the heat-resistant layer is 50%-99%; and / or The mass content of the non-fluoropolymer binder particles in the bonding layer is 35%-95%. The separator film according to any one of claims 5-6, wherein, The bonding layer further comprises fluoropolymer binder particles; Optionally, the mass content of the non-fluoropolymer binder particles in the bonding layer is greater than the mass content of the fluoropolymer binder particles in the bonding layer; Optionally, the particle size of the fluoropolymer binder particles is greater than the particle size of the non-fluoropolymer binder particles; Optionally, the fluoropolymer binder particles comprise aggregates of primary particles. The separator film according to any one of claims 1 to 7, wherein The heat-resistant 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 polyphenylene sulfide-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, polyether ether ketone-based organic particles; Optionally, the thermosetting resin polymer comprises one or more of phenol formaldehyde resin-based organic particles, polymer particles containing triazine ring structure units, epoxy resin-based organic particles, unsaturated polyester resin-based organic particles, urea-formaldehyde resin-based organic particles, furan resin-based organic particles; Optionally, the cross-linked polymer comprises one or more of cross-linked styrene-based organic particles, silicon-containing organic cross-linked resin particles. The separator film according to any one of claims 1 to 8, wherein The heat-resistant organic particles have a true density of 1.0 g / cm 3 -2.0 g / cm 3 . The isolation film according to any one of claims 1-9, wherein The heat-resistant organic particles comprise at least one of a thermosetting resin polymer or a cross-linked polymer, and the cyclic voltammogram of the heat-resistant organic particles in the first cycle has no oxidation peak in the voltage range of 2.5V to 4.4V; and / or, The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer, and an initial thermal weight loss temperature T 3d greater than or equal to 240°C; and / or, The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer, and the heat-resistant organic particles have no glass transition temperature below 200°C. The separator film according to any one of claims 1 to 10, wherein The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer, and the heat-resistant organic particles have a swelling degree of 3% or less when immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days; and / or, The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer, and the heat-resistant organic particles have a dissolution rate of 3% or less when immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days; and / or, The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer, and the heat-resistant organic particles have no melting point. The separator film according to any one of claims 1 to 11, wherein The heat-resistant organic particles include at least one of a thermosetting resin polymer or a crosslinked polymer; optionally, the heat-resistant organic particles include one or more of a phenol resin-based organic particle, a polymer particle containing a triazine ring structure unit, a crosslinked styrene-based organic particle, a silicon-containing organic crosslinked resin particle. The separator film according to any one of claims 1 to 12, wherein The heat-resistant organic particles include a phenol resin-based organic particle, and the phenol resin-based organic particle satisfies one or more of the following conditions (1) to (4): (1) The phenol resin-based organic particle is a thermosetting resol resin; (2) The phenol resin-based organic particle has no glass transition temperature; (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 particle has a volume distribution particle size Dv50 of 160 nm to 800 nm. The separator film according to any one of claims 1 to 13, wherein The heat-resistant organic particles include a polymer particle containing a triazine ring structure unit, and the polymer particle containing a triazine ring structure unit satisfies one or more of the following conditions (1) to (4): (1) The polymer particle containing a triazine ring structure unit includes a bridging structure connecting the triazine ring structure units; (2) The polymer particle containing a triazine ring structure unit has no glass transition temperature; (3) the initial thermal weight loss temperature T of the polymer particles containing the triazine ring structural unit is 3d 290°C to 345°C; (4) The polymer particle containing a triazine ring structure unit has a volume distribution particle size Dv50 of 160 nm to 800 nm. The separator film according to claim 14, 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. The separator film according to any one of claims 14-15, wherein, The polymer particle containing a triazine ring structure unit further has a substituent on the triazine ring structure 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 group. The separator film according to any one of claims 14 to 16, wherein The polymer particle containing a triazine ring structure unit includes at least one of a melamine-aldehyde-based polymer and a derivative thereof, an etherified melamine-aldehyde-based polymer and a derivative thereof, an etherified melamine-aldehyde-polyol polymer and a derivative thereof, an etherified melamine-aldehyde-polybasic acid polymer and a derivative thereof, and an etherified melamine-aldehyde-polyamine amide polymer and a derivative thereof. The separator film according to claim 17, wherein The melamine formaldehyde polymers 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 formaldehyde polymers 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 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, butyl etherified melamine formaldehyde-polyester polyol polymer; and / or, The etherified melamine formaldehyde-polybasic acid polymers 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 formaldehyde-polyamine amide polymers 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. The separator film according to any one of claims 1 to 18, wherein The heat-resistant organic particles include crosslinked styrene-based organic particles, and the crosslinked styrene-based organic particles include styrene or styrene derivative structural units and crosslinking 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. The separator film according to any one of claims 1 to 19, wherein The heat-resistant 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 size Dv50 of the crosslinked styrene-based organic particles is 80 nm to 300 nm. The separator film according to any one of claims 1 to 20, wherein The heat-resistant organic particles include silicon-containing organic crosslinking resin particles, and the silicon-containing organic crosslinking resin particles satisfy one or more of the following conditions (1) to (4): (1) The silicon-containing organic crosslinking resin particles contain a benzene ring structure; (2) The silicon-containing organic crosslinking resin particles have no glass transition temperature; (3) the initial thermal weight loss temperature T 3d 240°C to 330°C; (4) The volume distribution particle size Dv50 of the silicon-containing organic crosslinking resin particles is 80 nm to 800 nm. The separator film according to claim 21, wherein 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. The separator film according to any one of claims 21-22, wherein, The heat-resistant organic particles include silicon-containing organic crosslinking resin particles, the silicon-containing organic crosslinking resin particles include a crosslinking structural unit, and the crosslinking structural unit includes a divinylbenzene structural unit. The separator film according to claim 23, 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, an ethylene glycol dimethacrylate structural unit, a 1,4-butanediol diacrylate structural unit, a 1,6-hexanediol diacrylate structural unit, a 1,8-octanediol diacrylate structural unit, a trimethylolpropane triacrylate structural unit, a pentaerythritol trimethacrylate structural unit, a tetraethylene glycol dimethacrylate structural unit, a tripropyleneglycol diacrylate structural unit, a 2,2,4-trimethyladipic acid bis[2-ethylaziridine] structural unit, a 1,1-sebacic acid bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine] structural unit, a trimethylolpropane tris(2-methyl-1-aziridinylpropionate) structural unit, a trimethylolpropane-tris[3-(2-methylaziridinyl)propionate] structural unit, a pentaerythritol tris(3-aziridinyl)propionate structural unit. The separator film according to any one of claims 1 to 24, wherein The average particle diameter of the non-fluoropolymer binder particles is 6 μm to 15 μm; and / or, The non-fluoropolymer binder particles include aggregates of primary particles. The separator film according to any one of claims 1 to 25, wherein The glass transition temperature of the non-fluoropolymer binder particles is 0°C to 70°C. The separator film according to claim 26, wherein The non-fluoropolymer binder particles include a hard monomer, a soft monomer, and a crosslinking monomer; optionally, the crosslinking monomer includes at least one of a hydroxyl group, a carboxyl group, an ester group, an amide group, a sulfonic acid group, a sulfonate. The separator film according to claim 27, wherein The hard monomer includes one or more of methyl methacrylate, ethyl methacrylate, styrene, acrylonitrile, methacrylonitrile; and / or, The soft monomer includes one or more of ethyl acrylate, n-butyl acrylate, isooctyl acrylate, octyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, lauryl methacrylate, n-octyl methacrylate; and / or, The crosslinking monomer includes one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, diacetone acrylamide, acryloyl acetic acid ethyl ester methacrylate, acrylic acid, methacrylic acid, itaconic acid, styrene sulfonic acid, sodium vinyl sulfonate. The separator film according to any one of claims 1 to 25, wherein The non-fluoropolymer binder particles comprise a first glass transition temperature T g and a second glass transition temperature T g , and the first glass transition temperature and the second glass transition temperature are different. Optionally, the first glass transition temperature T g less than or equal to 25°C, Optionally, the second glass transition temperature T g greater than 25 °C. The separator film according to claim 29, wherein said first glass transition temperature T g from -20°C to 25°C; and / or, said second glass transition temperature T g is from 26°C to 70°C. The separator film according to any one of claims 29-30, wherein, The non-fluoropolymer binder particles include an acrylate-based copolymer, and / or the non-fluoropolymer binder particles include at least one of an ester group, a carboxyl group, an acrylamide group, a carbonyl group, an amide group, a nitrile group. The separator film according to any one of claims 29-31, wherein, The non-fluoropolymer binder particles include a first polymer and a second polymer, the first polymer and the second polymer each including an acrylate-based copolymer. The separator film according to claim 32, wherein The first polymer and / or the second polymer comprises a first polymeric monomer, the structure of the first polymeric monomer comprising: R1 includes a hydrogen atom or an alkyl group of 1 to 12 carbon atoms, and R2 includes an alkyl group of 1 to 12 carbon atoms. The separator film according to any one of claims 32-33, wherein, The first polymer includes a second polymeric monomer, the structure of the second polymeric monomer including: R3comprises a hydrogen atom, a substituted or unsubstituted alkyl group of 1 to 6 carbon atoms. The separator film according to any one of claims 32 to 34, wherein The first polymer and / or the second polymer includes a third polymeric monomer, the structure of the third polymeric monomer including: R4comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, and R5comprises a hydrogen atom, a hydroxyl-substituted alkyl group of 1 to 6 carbon atoms, or an alkoxy group of 1 to 6 carbon atoms. The separator film according to any one of claims 32 to 35, wherein The second polymer includes a fourth polymerized monomer, the structure of the fourth polymerized monomer including: R6comprises a hydrogen atom or an alkyl group of 1 to 6 carbon atoms. The separator film according to any one of claims 32 to 36, wherein The mass ratio of the first polymer to the second polymer is 1:(0.1-10), which can be 1:(0.5-3). A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator of any one of claims 1-37, the separator being disposed between the positive electrode sheet and the negative electrode sheet. A battery device comprising a plurality of the secondary battery cell of claim 38. An electric device comprising the secondary battery cell of claim 38 or the battery device of claim 39.

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