Organic polymer particle and preparation method therefor, separator, secondary cell, battery device, and electric device

Abstract

An organic polymer particle and a preparation method therefor, a separator, a secondary cell, a battery device, and an electric device. The separator comprises a porous base film and a coating located on at least one side of the porous base film; the coating comprises the organic polymer particle; the organic polymer particle contains triazine ring structural units and polar functional groups; and the polar functional groups comprise one or more of ester groups, carbonyl groups, hydroxyl groups, carboxyl groups, amide groups, sulfonic acid groups, and amino groups. The secondary cell has high reliability, high gravimetric energy density, and good dynamic performance.

Description

Organic polymer particle, method for producing the same, separator, secondary battery cell, battery device, and electric device

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202410947865.2, filed on July 15, 2024, entitled “Organic Polymer Particle, Method for Producing the Same, Separator, Battery Cell, and Electric Device,” and Chinese Patent Application No. 202411388731.8, filed on September 30, 2024, entitled “Organic Polymer Particle, Method for Producing the Same, Separator, Secondary Battery Cell, Battery Device, and Electric Device,” the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present disclosure relates to an organic polymer particle, a method for producing the same, a separator, a secondary battery cell, a battery device, and an electric device. BACKGROUND

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

[0005] The present disclosure provides an organic polymer particle, a method for producing the same, a separator, a secondary battery cell, a battery device, and an electric device, which have high reliability, high-quality energy density, and good kinetic performance.

[0006] In a first aspect, the present disclosure provides a separator, comprising a porous base film and a coating layer located on at least one side of the porous base film, the coating layer comprising organic polymer particles, the organic polymer particles containing a triazine ring structural unit and a polar functional group, the polar functional group comprising one or more of an ester group, a carbonyl group, a hydroxyl group, a carboxyl group, an amide group, a sulfonic acid group, and an amino group.

[0007] The organic polymer particles have a small density, and a secondary battery cell using the same can have a higher mass energy density. The organic polymer particles of the present disclosure contain triazine ring structure units, and the triazine ring structure is rigid, which can make the organic polymer particles have good heat resistance. Thus, when the organic polymer particles are used in a separator film, a force resisting the shrinkage of the separator film can be generated, so that 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. Meanwhile, the organic polymer particles of the present disclosure also contain polar functional groups, which include one or more of an ester group, a carbonyl group, a hydroxyl group, a carboxyl group, an amide group, a sulfonic acid group, and an amino group. These polar functional groups can produce stronger interactions, such as van der Waals forces, hydrogen bonds, or ionic bonds, with the binder in the coating layer of the separator film, so that the adhesion between the coating layer and the porous base film of the separator film, and the adhesion between the polymer particles and the polymer particles, are stronger, thereby improving the overall structural stability of the separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell. In addition, these polar functional groups also help to improve the electrolyte wettability of the separator film, reduce the internal resistance of the secondary battery cell, and improve the kinetic performance of the secondary battery cell. Therefore, the separator film of the present disclosure can make the secondary battery cell have high reliability, high mass energy density, and good kinetic performance

[0008] In some embodiments, the organic polymer particles include a bridging structure connecting the triazine ring structure units.

[0009] In some embodiments, the bridging structure includes one or a combination of two or more of an alkylene group, an alkylene ether group, and an alkylene amine group.

[0010] In some embodiments, the triazine ring structure units further have a substituent group, which 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.

[0011] In some embodiments, the organic polymer particles are melamine formaldehyde polymers.

[0012] In some embodiments, the melamine formaldehyde polymers 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, trihydrazinotriazine formaldehyde, melamine-(2-amino-4-methylamino-1,3,5-triazine) formaldehyde, and melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde.

[0013] In some embodiments, the organic polymer particles are thermosetting resins.

[0014] In some embodiments, the organic polymer particles are amorphous polymers.

[0015] In some embodiments, the organic polymer particles have no melting point below 300℃.

[0016] The organic polymer particles of the present disclosure have no melting point below 300℃, which indicates that the organic polymer particles have good heat resistance and thermal stability, thereby better resisting thermal shrinkage of the separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0017] In some embodiments, the organic polymer particles have no glass transition temperature below 300℃.

[0018] The organic polymer particles have no glass transition temperature below 300℃, which indicates that the organic polymer particles have good heat resistance and thermal stability, thereby better resisting thermal shrinkage of the separator film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0019] In some embodiments, the organic polymer particles have a dissolution rate of less than or equal to 3% when immersed in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60℃ for 7 days.

[0020] The organic polymer particles have a low dissolution rate in organic solvents, high structural stability during long-term use of the secondary battery cell, and high chemical stability in electrolytes, thereby enabling the secondary battery cell to have long cycle stability.

[0021] In some embodiments, the organic polymer particles have a swelling degree of less than or equal to 3% when immersed in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60℃ for 7 days.

[0022] The organic polymer particles have a low swelling degree in organic solvents, high structural stability during long-term use of the secondary battery cell, thereby improving the problem of decreased air permeability of the separator film during use.

[0023] In some embodiments, the organic polymer particles have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.5V.

[0024] The organic polymer particles have no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.5V to 4.5V, indicating that the organic polymer particles are stable in the voltage range of 2.5V to 4.5V and have good electrochemical stability, and can be applied to high-voltage secondary battery cells to improve the operating voltage and energy density of the secondary battery cell.

[0025] In some embodiments, the volume distribution particle size Dv50 of the organic polymer particles is 180 nm-800 nm.

[0026] In some embodiments, the true density of the organic polymer particles is 1.1 g / cm 3 -1.7 g / cm 3 . Thus, the secondary battery cell employing the separator film of the present disclosure can have a higher mass energy density.

[0027] In some embodiments, the mass content of the organic polymer particles in the coating layer is 50%-99% based on the total mass of the coating layer.

[0028] In some embodiments, the thickness of the coating layer is 0.5 μm-5 μm.

[0029] In some embodiments, the area density of the coating layer is 0.45 g / m 2 -4.5 g / m 2 .

[0030] In some embodiments, the ratio of the volume distribution particle size Dv50 of the organic polymer particles to the average pore size of the porous base film is greater than or equal to 2.5.

[0031] In some embodiments, the peeling force between the coating layer and the porous base film is greater than or equal to 60 N / m.

[0032] In some embodiments, the longitudinal heat shrinkage of the separator film is less than or equal to 2.0% when heated at 130°C for 1 h.

[0033] In some embodiments, the transverse heat shrinkage of the separator film is less than or equal to 2.0% when heated at 130°C for 1 h.

[0034] In some embodiments, the longitudinal tensile strength of the separator film is greater than or equal to 2140 kg / cm 2 .

[0035] In some embodiments, the transverse tensile strength of the separator film is greater than or equal to 1840 kg / cm 2 .

[0036] In some embodiments, the puncture strength of the separator film is greater than or equal to 410 kgf.

[0037] In a second aspect, the present disclosure provides an organic polymer particle containing a triazine ring structural unit and a polar functional group, the polar functional group including one or more of an ester group, a carbonyl group, a hydroxyl group, a carboxyl group, an amide group, a sulfonic acid group, and an amino group.

[0038] In some embodiments, the organic polymer particles comprise a bridging structure connecting the triazine ring structure units.

[0039] In some embodiments, the bridging structure comprises one or a combination of two or more of an alkylene, an alkylene ether, an alkylene amine.

[0040] In some embodiments, the triazine ring structure units further comprise a substituent comprising one or more of a combination of an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an amine group, a hydroxyl group, a halogen.

[0041] In some embodiments, the organic polymer particles are melamine formaldehyde polymers.

[0042] In some embodiments, the melamine formaldehyde polymers comprise 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.

[0043] In some embodiments, the organic polymer particles are thermosetting resins.

[0044] In some embodiments, the organic polymer particles are amorphous polymers.

[0045] In some embodiments, the organic polymer particles have no melting point below 300°C.

[0046] In some embodiments, the organic polymer particles have no glass transition temperature below 300°C.

[0047] In some embodiments, the organic polymer particles have a dissolution rate of less than or equal to 3% when soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days.

[0048] In some embodiments, the organic polymer particles have a swelling degree of less than or equal to 3% when soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days.

[0049] In some embodiments, the organic polymer particles have no oxidation peak in a cyclic voltammetry curve of the first cycle in a voltage range of 2.5V to 4.5V.

[0050] In some embodiments, the volume distribution particle size Dv50 of the organic polymer particles is 180 nm-800 nm.

[0051] In some embodiments, the true density of the organic polymer particles is 1.1 g / cm 3 -1.7 g / cm 3 .

[0052] In a third aspect, the present disclosure provides a method for preparing organic polymer particles, comprising the following steps: mixing an amine-substituted triazine compound, an aldehyde compound, and a modifier, and reacting at a first temperature in an alkaline environment to obtain a precursor containing a triazine ring structure, the modifier having a polar functional group or containing an acid radical ion capable of forming a polar functional group, and the polar functional group including one or more of an ester group, a carbonyl group, a hydroxyl group, a carboxyl group, an amide group, a sulfonic acid group, and an amino group; heating and curing the obtained precursor containing a triazine ring structure at a second temperature, and then crushing to obtain organic polymer particles containing a triazine ring structure unit and a polar functional group.

[0053] In some embodiments, the first temperature is 70°C-95°C.

[0054] In some embodiments, the reaction time at the first temperature is 8h-12h.

[0055] In some embodiments, the pH of the alkaline environment is 8.0 to 9.5.

[0056] In some embodiments, the second temperature is 180°C-290°C.

[0057] In some embodiments, the heating and curing time at the second temperature is 1h-8h.

[0058] In some embodiments, the molar ratio of the aldehyde compound to the amine-substituted triazine compound is 1.75:1-3:1.

[0059] In some embodiments, the mass of the modifier is 0.5%-3.5% of the total mass of the amine-substituted triazine compound and the aldehyde compound.

[0060] In some embodiments, the modifier includes one or more of a polyol, a polyacid, a hydroxy acid, a hydroxyl-containing amide compound, urea, a polyamine, a sulfite, and an enol oligomer.

[0061] In some embodiments, the amine-substituted triazine compound comprises one or more of the following compounds of the general formula, R1, R2 are each independently selected from any one of H, -NH2, C1-C8 alkyl, R3 is selected from any one of H, -NH2, -NHR4, C1-C8 alkyl, C2-C8 alkenyl, phenyl, C7-C12 alkylphenyl, C7-C12 phenylalkyl, C5-C8 cycloalkyl, R4 is selected from any one of -NH2, C1-C8 alkyl.

[0062] In some embodiments, the amine-substituted triazine compound comprises 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, trihydrazino-s-triazine, 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.

[0063] In some embodiments, the aldehyde compound comprises one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0064] In a fourth aspect, the present disclosure provides a secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator film of the first aspect of the present disclosure, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

[0065] In a fifth aspect, the present disclosure provides an electric device comprising a plurality of the secondary battery cell of the fourth aspect of the present disclosure.

[0066] In a sixth aspect, the present disclosure provides an electric device comprising the secondary battery cell of the fourth aspect of the present disclosure or the electric device of the fifth aspect of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments of the present disclosure. Obviously, the drawings described below only constitute some of the embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained from the drawings without creative labor.

[0068] FIG. 1 shows a schematic diagram of a secondary battery cell according to some embodiments of the present disclosure.

[0069] FIG. 2 shows a schematic diagram of an electric device according to some embodiments of the present disclosure.

[0070] In the drawings, the drawings are not necessarily drawn according to the actual proportions. DETAILED DESCRIPTION

[0071] Hereinafter, specific embodiments of the organic polymer particles and the method for producing the same, 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 description is omitted. For example, there will be cases where detailed description of matters known well and repeated description 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.

[0072] The "range" disclosed in the present disclosure is defined in the form of a lower limit and an upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can include or not include the end value, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also anticipated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, the following ranges are all anticipated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise stated, the numerical range "a-b" represents a shorthand notation for any real combination of numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is only a shorthand notation for these numerical combinations. In addition, when a parameter is expressed as ≥2 integers, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0073] If not particularly specified, all the embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0074] If not particularly specified, all the technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0075] If not particularly specified, all the steps of the present disclosure can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0076] If not particularly specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects, rather than to describe a specific order or primary and secondary relationship.

[0077] In the present disclosure, the terms "a plurality of" and "a plurality of" refer to two or more.

[0078] In the description of the embodiments of the present disclosure, if not particularly specified, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be above or above the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be below or below the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0079] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25℃.

[0080] 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.

[0081] The secondary battery cells provided in the embodiments of this disclosure may include, but are not limited to, lithium battery cells and sodium battery cells, such as lithium-ion battery cells, sodium-ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0082] The secondary battery cell provided in the embodiments of this disclosure includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this disclosure are not limited in this regard. The secondary battery cell also includes an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0083] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple secondary battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0084] In some embodiments, a battery cell assembly is typically formed by arranging multiple secondary battery cells.

[0085] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple secondary battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple secondary battery cells together with cable ties.

[0086] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0087] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0088] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple secondary battery cells to the housing.

[0089] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0090] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0091] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0092] The technical solutions described in this disclosure are applicable to various electrical devices that use secondary battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Secondary battery cells and battery devices are used to store or provide electrical energy.

[0093] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0094] In the context of this disclosure, the "organic polymer particles" in the coating of the separator membrane primarily serve to improve heat resistance and have virtually no adhesive properties.

[0095] The separator is a crucial component supporting the electrochemical processes of charging and discharging in a secondary battery cell. Commonly used separators are often made of polyolefins; however, polyolefins have poor heat resistance and are prone to softening or melting at high temperatures, which can lead to short circuits in the secondary battery cells. To improve the heat resistance of the separator, a coating is usually applied. Boehmite, alumina, and other inorganic particles are commonly used heat-resistant fillers; however, these fillers have high density and a large mass for the same bulk volume, thus affecting the energy density of the secondary battery cells.

[0096] Based on this, embodiments of the present disclosure provide an organic polymer particle that, when used in a separator membrane, enables secondary battery cells to possess high reliability, high energy density, and good kinetic performance.

[0097] The organic polymer particles disclosed herein contain triazine ring structural units and polar functional groups, including one or more of ester, carbonyl, hydroxyl, carboxyl, amide, sulfonic acid, and amino groups.

[0098] Organic polymer particles have low density, allowing secondary battery cells to achieve higher gravimetric energy density. The organic polymer particles disclosed herein contain triazine ring structural units. The high rigidity of the triazine ring structure gives the organic polymer particles good heat resistance. Therefore, when used in a separator, these organic polymer particles can generate forces to resist separator shrinkage, thereby improving the overall thermal shrinkage of the separator, enhancing its heat resistance, and increasing the reliability of the secondary battery cell. Simultaneously, the organic polymer particles disclosed herein also contain polar functional groups, including one or more of ester, carbonyl, hydroxyl, carboxyl, amide, sulfonic acid, and amino groups. These polar functional groups can generate stronger interactions with the binder in the separator coating, such as van der Waals forces, hydrogen bonds, or ionic bonds. This results in stronger adhesion between the separator coating and the porous base membrane, and between polymer particles, thereby improving the overall structural stability of the separator, enhancing its heat resistance, and increasing the reliability of the secondary battery cell. Furthermore, these polar functional groups also help improve the electrolyte wettability of the separator, reduce the internal resistance of the secondary battery cells, and enhance the kinetic performance of the secondary battery cells. Therefore, the organic polymer particles disclosed herein, when used in the separator, enable the secondary battery cells to possess high reliability, high energy density, and good kinetic performance.

[0099] The organic polymer particles disclosed herein also include bridging structures that connect the triazine ring structural units.

[0100] Organic polymer particles contain multiple triazine ring structural units in their molecular structure. The bridging structure refers to the groups that connect the triazine ring structural units, and the bridging structures may be the same or different.

[0101] In some embodiments, the bridging structure may include one or more of alkylene, alkylene ether, and alkylene amine.

[0102] In some embodiments, the triazine ring structural unit may also have substituents, which may include one or more combinations of alkyl, alkenyl, phenyl, cycloalkyl, amino, hydroxyl, and halogen.

[0103] In some embodiments, the organic polymer particles may be melamine aldehyde polymers.

[0104] In some embodiments, melamine aldehyde polymers may include melamine formaldehyde polymers and their derivatives.

[0105] Optionally, melamine-formaldehyde polymers may include one or more of the following: melamine-formaldehyde, benzyl melamine-formaldehyde, melamine-benzene 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, trihydrazine-triazine formaldehyde, melamine-(2-amino-4-methylamino-1,3,5-triazine)formaldehyde, and melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine)formaldehyde.

[0106] The organic polymer particles disclosed herein are thermosetting resins.

[0107] The organic polymer particles disclosed herein are amorphous polymers.

[0108] In some embodiments, the true density of the organic polymer particles can be 1.1 g / cm³. 3 -1.7g / cm 3 .

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

[0110] The organic polymer particles disclosed herein are poorly soluble in both water and organic solvents, such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), and chloroform, at 25°C. They are also insoluble in the mobile phase used in gel permeation chromatography and the molecular weight of the organic polymer particles cannot be determined by gel permeation chromatography.

[0111] In some embodiments, the organic polymer particles have no melting point below 300°C.

[0112] The organic polymer particles disclosed herein have no melting point below 300°C, indicating that the organic polymer particles have good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of the separator, improve the heat resistance of the separator, and enhance the reliability of the secondary battery cell.

[0113] Melting point can be tested as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of a differential scanning calorimeter (DSC), level it, and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. The DSC curve is used to determine whether the organic polymer particles have a melting point below 300℃.

[0114] The statement that organic polymer particles have no melting point below 300℃ means that the DSC curve of the organic polymer particles has no melting peak in the temperature range below 300℃.

[0115] In some embodiments, the organic polymer particles have no glass transition temperature below 300°C.

[0116] The organic polymer particles have no glass transition temperature below 300℃, indicating that they have good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of the separator, improve the heat resistance of the separator, and enhance the reliability of the secondary battery cells.

[0117] Glass transition temperature T g The test can be performed as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of the differential scanning calorimeter (DSC), level it, and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. The DSC curve can be used to determine whether the organic polymer particles have a glass transition temperature T below 300℃. g .

[0118] Glass transition temperature T g It refers to the transition temperature from the glassy state to the elastic state, which shows a step-like change on the DSC curve.

[0119] Organic polymer particles have no glass transition temperature T below 300°C. g This means that the DSC curve of organic polymer particles does not show a step-like change in the range below 300℃.

[0120] In some embodiments, the dissolution rate of organic polymer particles soaked in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 at 60°C for 7 days can be less than or equal to 3%.

[0121] Organic polymer particles have a low dissolution rate in organic solvents, resulting in high structural stability during long-term use of secondary battery cells and high chemical stability in electrolytes. This allows secondary battery cells to have long-cycle stability.

[0122] In some embodiments, the swelling degree of organic polymer particles soaked in a mixed solvent of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 at 60°C for 7 days can be less than or equal to 3%.

[0123] Organic polymer particles have low swelling in organic solvents and high structural stability during long-term use of secondary battery cells, thereby improving the problem of decreased air permeability of the separator during use.

[0124] The dissolution rate of organic polymer particles can be tested as follows: Take an appropriate amount of sample (e.g., about 1g), and record its mass as m1. Place it in a semi-permeable membrane sample bag, seal it, and record the total mass of the sample bag as m2. The sample bag is permeable to the solvent but not to the sample. Immerse the sample bag in an appropriate amount of solvent (e.g., about 50g) at 60°C for 7 days. After that, remove the sample bag, drain it, dry it, and weigh the total mass of the sample bag again as m3. Dissolution rate = (m2-m3) / m1 × 100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0125] The swelling degree of organic polymer particles can be tested as follows: Take an appropriate amount of sample (e.g., about 1g), denoted as m1, and place it in a semi-permeable membrane sample bag. Seal the bag; the sample bag should be permeable to the solvent but not to the sample. Immerse the sample bag in an appropriate amount of solvent (e.g., about 50g) at 60°C for 7 days. After immersion, remove the sample bag and then remove the sample from the bag. Wipe away excess solvent and weigh the sample again, m2. Swelling degree = (m2-m1) / m1×100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0126] In some embodiments, the cyclic voltammetry curves of the organic polymer particles during the first cycle do not exhibit oxidation peaks in the voltage range of 2.5V to 4.5V.

[0127] The cyclic voltammetry curve of the organic polymer particles in the first cycle does not have an oxidation peak in the voltage range of 2.5V to 4.5V, indicating that the organic polymer particles are stable in the voltage range of 2.5V to 4.5V and have good electrochemical stability. They can be applied to high-voltage secondary battery cells to improve the working voltage and energy density of secondary battery cells.

[0128] The oxidation peak potential of organic polymer particles can be tested as follows: Organic polymer particles, binder polyacrylate, and conductive carbon black are dissolved in water at a solid-to-mass ratio of 64:7:29 to prepare a slurry. The slurry is coated onto aluminum foil as the positive electrode, and lithium foil is used as the negative electrode to assemble a coin cell. Cyclic voltammetry (CV) is performed on the coin cell at a scan rate of 0.10 mV / s, a voltage range of 2.50 V–5.00 V, for 3 cycles. The voltage corresponding to the peak point of the first cyclic voltammetry curve is taken as the oxidation peak potential. The electrolyte used in the test is LiPF6 with a concentration of 1 mol / L. The solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of 3:7.

[0129] In some embodiments, the volume distribution particle size Dv50 of the organic polymer particles can be 180nm-800nm.

[0130] Dv50 represents the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material. It can be measured using a laser particle size analyzer, referring to GB / T 19077-2016. During testing, add 1g of the sample to a clean small beaker, along with 20ml of deionized water. Sonicate at 53kHz / 120W for 5 minutes to ensure complete dispersion. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated solution to ensure uniform dispersion, then place it in the sample cell as required and begin measuring the particle size. A MasterSizer 3000 laser particle size analyzer can be used as the testing instrument.

[0131] This disclosure also provides a method for preparing organic polymer particles, which can prepare the above-mentioned organic polymer particles.

[0132] The preparation method of organic polymer particles includes the following steps: Amine-substituted triazine compounds, aldehyde compounds, and modifiers are mixed and reacted in an alkaline environment at a first temperature to obtain a precursor containing a triazine ring structure. The modifier has polar functional groups or contains acid radicals that can form polar functional groups. The polar functional groups include one or more of ester, carbonyl, hydroxyl, carboxyl, amide, sulfonic acid, and amino groups. The obtained precursor containing the triazine ring structure is then heated and cured at a second temperature, followed by crushing to obtain organic polymer particles containing triazine ring structural units and polar functional groups. After heating and curing, the precursor containing the triazine ring structure forms a bridging structure between the triazine ring structural units.

[0133] The preparation method provided in this embodiment yields organic polymer particles with good heat resistance.

[0134] The preparation method provided in this disclosure uses a modifier capable of forming polar functional groups, including one or more of ester, carbonyl, hydroxyl, carboxyl, amide, sulfonic acid, and amino groups. These polar functional groups can generate stronger interactions with the binder in the separator coating, such as van der Waals forces, hydrogen bonds, or ionic bonds. This results in stronger adhesion between the separator coating and the porous base membrane, and between polymer particles, thereby improving the overall structural stability of the separator, enhancing its heat resistance, and increasing the reliability of the secondary battery cells. Furthermore, these polar functional groups also help improve the electrolyte wettability of the separator, reduce the internal resistance of the secondary battery cells, and improve the kinetic performance of the secondary battery cells.

[0135] In some embodiments, the mass of the modifier may be 0.5% to 3.5% of the total mass of the amine-substituted triazine compound and the aldehyde compound, for example, it may be 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.5%, or any range of the above values.

[0136] When the mass fraction of the modifier is within the above range, it can improve the adhesion between the coating of the separator and the porous base film, and between polymer particles, and also give the separator better heat resistance and higher mechanical strength.

[0137] In some embodiments, the modifier may include one or more of polyols, polyacids, hydroxy acids, hydroxyl-containing amide compounds, urea, polyamines, sulfites, and enol oligomers.

[0138] Polyols may include alkyl polyols and aryl polyols, and may be selected from one or more of C2-C8 alkyl diols, phenylene glycol and its derivatives, and biphenyl glycol and its derivatives.

[0139] The polybasic acid may include alkyl polybasic acid and aryl polybasic acid, and may be selected from one or more of C4-C12 alkyl dibasic acid, phthalic acid and its derivatives.

[0140] Hydroxy acids may include alkyl hydroxy acids and aryl hydroxy acids, and may optionally include benzoic acid and its derivatives.

[0141] Hydroxyl-containing amide compounds may include alkylolamides and arylolamides, and may optionally include hydroxylated benzamides and their derivatives.

[0142] Polyamines may include alkyl polyamines and aryl polyamines, and may be selected from one or more of C2-C8 alkyl diamines, phenylenediamines and their derivatives.

[0143] Enol oligomers may include polyvinyl alcohol oligomers and polyacryl alcohol oligomers.

[0144] Optionally, the molecular weight of the enol oligomer is below 5000, and optionally below 2000.

[0145] Optionally, the modifier may include, but is not limited to, ethylene glycol, 1,2-propanediol, 1,4-butanediol, pentanediol, hexanediol, phenylene glycol, biphenyl glycol, succinic acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic acid, isophthalic acid, 5-methylisophthalic acid, p-hydroxybenzoic acid, m-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid, 4-hydroxy-3,5-dimethylbenzoic acid. One or more of the following: 3-hydroxy-5-methylbenzoic acid, 3,5-dihydroxybenzoic acid, 4-hydroxysalicylic acid, salicylamide, 4-methylsalicylic acid, 5-methylsalicylic acid, 2,6-dihydroxybenzamide, 2,4-dihydroxybenzamide, ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, urea, sodium sulfite, sodium metabisulfite, polyvinyl alcohol oligomers, and polyacrylamide oligomers.

[0146] In some embodiments, the second temperature can be 180℃-290℃, for example, it can be 180℃, 185℃, 190℃, 195℃, 200℃, 210℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, or any range of the above values.

[0147] Heating and curing temperatures within the above range are beneficial for the formation of organic polymer particles with better heat resistance from precursors containing triazine ring structures.

[0148] Optionally, the heat curing temperature can be 200℃-285℃, 210℃-285℃, 220℃-285℃, or 230℃-285℃.

[0149] In some embodiments, the curing time at the second temperature can be 1h-8h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, or any range of the above values.

[0150] When the heating and curing time is within the above range, it is beneficial for the precursor containing the triazine ring structure to form organic polymer particles with better heat resistance.

[0151] Optionally, the curing time can be 2-8 hours.

[0152] In some embodiments, the oxygen-containing atmosphere may include oxygen and an inert gas. Optionally, the inert gas may be one or more of nitrogen, argon, and helium, among others. In some embodiments, the volume fraction of oxygen in the oxygen-containing atmosphere may be 5%-50%. Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere may be 10%-30%. More preferably, the oxygen-containing atmosphere may be an air atmosphere.

[0153] In some embodiments, the organic polymer particles containing triazine ring structural units further include sieving and demagnetizing steps after crushing.

[0154] In some embodiments, the first temperature can be 70°C-95°C.

[0155] In some embodiments, the reaction time at the first temperature can be 8-12 hours.

[0156] In some embodiments, the pH of the alkaline environment can be from 8.0 to 9.5.

[0157] In some embodiments, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 1.75:1 to 3:1, for example, it can be 1.75:1, 1.8:1, 1.9:1, 2:1, 2.05:1, 2.1:1, 2.15:1, 2.2:1, 2.25:1, 2.3:1, 2.35:1, 2.4:1, 2.45:1, 2.5:1, 2.55:1, 2.6:1, 2.65:1, 2.7:1, 2.75:1, 2.8:1, 2.85:1, 2.9:1, 2.95:1, 3:1, or any range of the above ratios. Alternatively, the molar ratio of the aldehyde compound to the amine-substituted triazine compound can be 2.05:1-3:1, 2.15:1-3:1, 2.25:1-3:1, 2.3:1-3:1, 2.35:1-3:1, 2.4:1-3:1, 2.45:1-3:1, or 2.5:1-3:1.

[0158] In some embodiments, aldehyde compounds may include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

[0159] In some embodiments, the amine-substituted triazine compound may include one or more compounds of the following general formula, wherein R1 and R2 are each independently selected from H, -NH2, and C1-C8 alkyl, R3 is selected from H, -NH2, -NHR4, C1-C8 alkyl, C2-C8 alkenyl, phenyl, C7-C12 alkylphenyl, C7-C12 phenylalkyl, and C5-C8 cycloalkyl, and R4 is selected from -NH2 and C1-C8 alkyl. Optionally, R3 is selected from -NH2 or -NHR4.

[0160] Optionally, the amine-substituted triazine compound may include melamine, benzomelamine, 2,4-diamino-1,3,5-triazine, 6-methyl-1,3,5-triazine-2,4-diamine, 2,4,6-triethylamino-1,3,5-triazine, trihydrazine, 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- One or more of the following: 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-triazine-2-yl)methanol, and 2-chloro-4,6-diamino-1,3,5-triazine.

[0161] Alternatively, the amine-substituted triazine compound may include one or more of melamine, benzomelamine, 2,4-diamino-1,3,5-triazine, 6-methyl-1,3,5-triazine-2,4-diamine, 2,4,6-triethylamino-1,3,5-triazine, trihydrazine, 2-amino-4-methylamino-1,3,5-triazine, and 2,4-diamino-6-dimethylamino-1,3,5-triazine.

[0162] This disclosure also provides a separator membrane. The separator membrane includes a porous base membrane and a coating located on at least one side of the porous base membrane. The coating includes an adhesive and organic polymer particles of this disclosure or organic polymer particles prepared by the methods of this disclosure.

[0163] Both the porous base membrane and the coating have a porous structure, which allows the separator to have good air permeability, facilitating the passage of ions. The organic polymer particles in the coating are interconnected and fixed by a binder, and the gaps between the organic polymer particles can form a porous structure.

[0164] In some embodiments, the mass content of organic polymer particles in the coating may be 50%-99% based on the total mass of the coating.

[0165] Optionally, the mass content of organic polymer particles in the coating can be 60%-99%, 70%-99%, 80%-99%, 85%-99%, 88%-99%, 80%-97%, 85%-97%, 88%-97%, 80%-95%, 85%-95%, or 88%-95%.

[0166] In some embodiments, the adhesive in the coating may include, but is not limited to, one or more of polyacrylate adhesives and nitrile rubber adhesives.

[0167] In some embodiments, the coating may also include a dispersant. The dispersant may include, but is not limited to, one or more of polyacrylic acid dispersants and carboxymethyl cellulose dispersants.

[0168] In some embodiments, the separator may also include polymer binder particles.

[0169] The "polymer binder particles" in the porous coating of the separator membrane play a role in improving the adhesion between the separator membrane and the electrode, but they have virtually no high-temperature resistance.

[0170] In some embodiments, polymer binder particles may be embedded in organic polymer particles and form protrusions on the coating surface.

[0171] In other embodiments, the coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on a porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer on the side away from the porous base membrane. Organic polymer particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0172] In some other embodiments, the coating of the separator includes a heat-resistant layer and an adhesive layer, the heat-resistant layer being disposed on one side of the porous base membrane, the adhesive layer being disposed on at least a portion of the surface of the other side of the porous base membrane, organic polymer particles being disposed in the heat-resistant layer, and polymer adhesive particles being disposed in the adhesive layer.

[0173] In some embodiments, the average particle size of the polymer binder particles can be 6 μm-18 μm.

[0174] In some embodiments, the polymer binder particles may include vinylidene fluoride polymer particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and comonomer.

[0175] Comonomers may include at least one of olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers.

[0176] Optionally, the comonomer may include at least one of the following: trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ether (e.g., perfluoro(methyl vinyl) ether, perfluoro(ethyl vinyl) ether, perfluoro(propyl vinyl) ether), perfluoro(1,3-m-dioxacyclopentene), and perfluoro(2,2-dimethyl-1,3-m-dioxacyclopentene).

[0177] In some embodiments, the coating thickness can be 0.5 μm-5 μm. The coating thickness refers to the thickness of the coating on one side of the porous base film. Optionally, the coating thickness can be 0.5 μm-4 μm, 0.5 μm-3 μm, 0.5 μm-2 μm, 0.8 μm-4 μm, 0.8 μm-3 μm, or 0.8 μm-2 μm.

[0178] In some embodiments, the areal density of the coating may be 0.45 g / m³. 2 -4.5g / m 2 .

[0179] In some embodiments, the porous base membrane may comprise a membrane or nonwoven web selected from any one or at least two of the following: polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, and polyvinylnaphthalene.

[0180] Porous base membranes can be single-layer thin films or multi-layer composite thin films. When a porous base membrane is a multi-layer composite thin film, the materials of each layer can be the same or different.

[0181] In some embodiments, the thickness of the porous base film can be 4μm-12μm, and optionally 4μm-9μm.

[0182] In some embodiments, the porosity of the porous base membrane can be 25%-60%, optionally 28%-50%.

[0183] In some embodiments, the ratio of the volume distribution particle size Dv50 of the organic polymer particles to the average pore size of the porous base membrane can be greater than or equal to 2.5.

[0184] The volume distribution particle size Dv50 of the organic polymer particles has the same unit, e.g., nm, as the average pore size of the porous base membrane.

[0185] This can reduce pore blockage and improve the air permeability and ion conduction properties of the separator.

[0186] In some embodiments, the average pore size of the porous base film can be 25 nm to 82 nm.

[0187] The average pore size of the porous membrane can be measured using a capillary porosity analyzer (bubble point method). An exemplary testing method is as follows: Take a circular sample with a diameter of 25 mm, and drop 3-5 drops of wetting solution onto it. After the sample is completely wetted, place it in a mold. Then, use an inert gas (such as nitrogen) to compress the wetting solution in the pores of the sample. The compression pressure and flow rate are inversely proportional to the pore size. The average pore size of the sample is obtained through software sampling and pressure-pore size conversion analysis. The testing instrument can be a PMI CFP 1500 pore size analyzer, with a testing pressure ranging from 100 psi to 350 psi.

[0188] In some embodiments, the thickness of the separator can be 5μm-14μm, optionally 5μm-12μm or 6μm-12μm. This is beneficial for improving the energy density of the secondary battery cell.

[0189] In some embodiments, the peel force between the coating and the porous base film can be greater than or equal to 60 N / m. This can improve the heat resistance of the separator, enhance the overall structural stability of the coating, and reduce powder shedding.

[0190] The peel force between the coating and the porous base membrane can be tested as follows: Cut the release liner into three 2.5cm × 15cm strips, attach the strips to a test steel plate, and attach 2cm wide test tape to the side of the release liner to be tested. Use a tensile testing machine, clamping the steel plate on one side and the tape on the other, to perform a 180° peel test. Take the average peel force of the three strips as the peel force between the release liner coating and the porous base membrane. The tensile rate is 50mm / min.

[0191] Optionally, the peel force between the coating and the porous base film can be greater than or equal to 70 N / m, greater than or equal to 75 N / m, greater than or equal to 80 N / m, greater than or equal to 85 N / m, greater than or equal to 90 N / m, greater than or equal to 95 N / m, or greater than or equal to 100 N / m.

[0192] In some embodiments, the longitudinal (MD) heat shrinkage rate of the separator film can be less than or equal to 2.0% after being heated at a constant temperature of 130°C for 1 hour.

[0193] In some embodiments, the transverse (TD) heat shrinkage rate of the separator film can be less than or equal to 2.0% after being heated at a constant temperature of 130°C for 1 hour.

[0194] In some embodiments, the longitudinal (MD) tensile strength of the separator can be greater than or equal to 2140 kg / cm². 2 .

[0195] In some embodiments, the transverse (TD) tensile strength of the separator can be greater than or equal to 1840 kg / cm².2 .

[0196] Organic polymer particles possess high hardness, high strength, and good abrasion resistance, which can improve the puncture strength of the separator. In some embodiments, the puncture strength of the separator can be greater than or equal to 410 kgf.

[0197] It should be noted that the coating parameters of the above-mentioned separators are coating parameters for one side of the porous base membrane. When the coating is applied to both sides of the porous base membrane, if the coating parameters of either side meet the requirements of this disclosure, it is considered to fall within the protection scope of this disclosure.

[0198] The separator membrane can be prepared according to methods known in the art.

[0199] In some embodiments, a slurry comprising organic polymer particles and a binder can be coated on at least one side of a porous base membrane, and after drying, a separation membrane is obtained.

[0200] In some embodiments, the slurry may further include polymer binder particles, which, after drying, are embedded in organic polymer particles and form protrusions on the coating surface.

[0201] In some embodiments, the method for preparing the separator membrane may include: applying a heat-resistant layer slurry comprising organic polymer particles and a binder to at least one side of a porous base membrane, and drying it to form a heat-resistant layer; and applying an adhesive layer slurry comprising polymer binder particles and a binder to at least a portion of the surface of the heat-resistant layer, and drying it to obtain the separator membrane.

[0202] In some embodiments, the method for preparing the separator membrane may include: coating a heat-resistant slurry comprising organic polymer particles and a binder onto one side of a porous base membrane, and coating an adhesive layer slurry comprising polymer binder particles and a binder onto at least a portion of the surface of the other side of the porous base membrane, and drying the slurry to obtain the separator membrane.

[0203] In some embodiments, the solvent for the slurry may be water, such as deionized water.

[0204] In some embodiments, the slurry may also include other components, such as dispersants and / or wetting agents.

[0205] This disclosure also provides a secondary battery cell. The secondary battery cell includes the separator provided in this disclosure. This allows the secondary battery cell to possess high reliability, high energy density, and good kinetic performance.

[0206] A secondary battery cell also includes a positive electrode, a negative electrode, and an electrolyte, with a separator disposed between the positive and negative electrodes. The positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process.

[0207] The secondary battery cells disclosed herein may include, but are not limited to, lithium battery cells, sodium battery cells, etc. The composition of the positive electrode, negative electrode and electrolyte may differ depending on the type of secondary battery cell.

[0208] [Positive electrode plate]

[0209] In some embodiments, the positive electrode may include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0210] Taking a lithium-ion battery cell as an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. In some embodiments, to further improve the energy density of the secondary battery cell, the positive electrode active material may include materials with the general formula Li a Ni b Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes but is not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes but is not limited to one or more of N, F, S and Cl.

[0211] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.1 Al 0.05 One or more of O2, LiFePO4, and LiMnPO4.

[0212] During the charging and discharging process, Li undergoes insertion / extraction and consumption in a single secondary battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before feeding. As the positive electrode active material is applied to a secondary battery cell, the molar Li content changes after charge-discharge cycles. Similarly, in the examples of positive electrode active materials in this disclosure, the molar O content is only a theoretical value. Lattice oxygen release causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0213] Taking sodium-ion battery cells as an example, the positive electrode active material can be one or more of the following, including but not limited to sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials. For example, the positive electrode active material can be, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In this case, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes, but is not limited to, H.+ Li + Na + K + and NH4 + One or more of the following, M' is a transition metal cation, optionally including but not limited to one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally one or more of F, Cl and Br.

[0214] The modified compounds for the positive electrode active materials of the aforementioned lithium battery cells and sodium battery cells can be obtained by doping and / or surface coating modifications of the positive electrode active materials.

[0215] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0216] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0217] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0218] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0219] [Negative electrode plate]

[0220] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0221] The negative electrode active material may be any material known in the art for use in secondary battery cells. As an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include, but are not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include, but are not limited to, one or more of elemental tin, tin oxide, and tin alloys.

[0222] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0223] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0224] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0225] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0226] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0227] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0228] In some embodiments, the negative electrode sheet can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0229] [Electrolytes]

[0230] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0231] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0232] Taking a lithium battery cell as an example, the electrolyte salt may include, but is not limited to, one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0233] Taking sodium battery cells as an example, the electrolyte salt may include, but is not limited to, one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium difluorosulfonyl imide (NaFSI), sodium difluoromethanesulfonyl imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0234] In some embodiments, the organic solvent may include, but is not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0235] In some embodiments, the electrolyte may also include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the secondary battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature performance, etc.

[0236] Optionally, the additive may include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), and ethylene sulfate (DTD).

[0237] Methods for preparing secondary battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a secondary battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the aforementioned electrolyte. After vacuum sealing, settling, and formation processes, a secondary battery cell is obtained.

[0238] Example

[0239] The following embodiments describe the disclosure of this disclosure in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0240] The preparation processes for organic polymer particles #1 to #9 are as follows.

[0241] Prepare a 10% sodium hydroxide aqueous solution for later use; add a commercially available 37% formaldehyde aqueous solution and different masses and types of modifiers to a container, adjust the pH value to 9.0-9.1 with the sodium hydroxide aqueous solution, then add the pH-adjusted mixture to the reaction vessel and stir, and heat to 50°C. After the temperature reaches 50°C, add melamine, then raise the reaction temperature to 80°C and react at this temperature for 10 hours; when the water turbidity point of the material reaches 1:3, put the material into a container, and then place it in a drying oven to cure at 250°C in air atmosphere for 6 hours. After that, after crushing, sand milling, sieving, and demagnetization, organic polymer particles are obtained.

[0242] Organic polymer particles #1: The modifier is p-hydroxybenzoic acid, and the mass of p-hydroxybenzoic acid is 1.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0243] Organic polymer particles #2: The modifier is p-hydroxybenzoic acid, and the mass of p-hydroxybenzoic acid is 0.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0244] Organic polymer particles #3: The modifier is p-hydroxybenzoic acid, and the mass of p-hydroxybenzoic acid is 2.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0245] Organic polymer particles #4: The modifier is p-hydroxybenzoic acid, and the mass of p-hydroxybenzoic acid is 3.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0246] Organic polymer particles #5: The modifier is polyvinyl alcohol, and the mass of polyvinyl alcohol is 1.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0247] Organic polymer particles #6: The modifier is 4-hydroxysalicylic acid amide, the mass of which is 1.5% of the total mass of formaldehyde and melamine, and the molar ratio of formaldehyde to melamine is 2.5:1.

[0248] Organic polymer particles #7: The modifier is sodium sulfite, and the mass of sodium sulfite is 1.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0249] Organic polymer particles #8: The modifier is p-phenylenediamine, and the mass of p-phenylenediamine is 1.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0250] Organic polymer particles #9: The modifier is urea, and the mass of urea is 1.5% of the total mass of formaldehyde and melamine. The molar ratio of formaldehyde to melamine is 2.5:1.

[0251] Commercially available melamine-formaldehyde resin granules were used as the organic polymer granules D1#. The molar ratio of formaldehyde to melamine in the melamine-formaldehyde resin was 2.5:1.

[0252] Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of the differential scanning calorimeter (DSC). Level the sample and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. Determine whether the organic polymer particles have a glass transition temperature T below 300℃ using the DSC curve. g And melting point.

[0253] Commercially available organic polymer particles D1# have a melting point between 110°C and 140°C.

[0254] The organic polymer particles 1# to 9# prepared above also meet the following characteristics: no melting point, and no glass transition temperature T below 300℃. g .

[0255] Next, the organic polymer particles prepared above were used in the separator to verify their impact on the performance of the separator and the secondary battery cells.

[0256] The manufacturing process of a secondary battery cell is as follows.

[0257] A commercially available 7 μm thick polyethylene microporous membrane was used as the porous base membrane. The prepared organic polymer particles, along with the dispersant sodium carboxymethyl cellulose and the binder polyacrylate, were mixed evenly in deionized water at a solid mass ratio of 90:2:8 to obtain a slurry. The slurry was then... 2 The solvent was uniformly coated onto both surfaces of the porous base membrane, and then dried to remove the solvent, resulting in a separator membrane. The coating thickness on one side of the porous base membrane was 1.5 μm, and the separator membrane thickness was 10 μm.

[0258] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1O2, positive electrode binder polyvinylidene fluoride (PVDF), and positive electrode conductive agent carbon black are added to N-methylpyrrolidone (NMP) in a mass ratio of 97:2:1 and thoroughly mixed to prepare a positive electrode slurry. The positive electrode slurry is then uniformly coated onto the positive electrode current collector aluminum foil, and subsequently dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0259] The negative electrode active material, fast-charging artificial graphite, the negative electrode conductive agent, acetylene black, the negative electrode binder, styrene-butadiene rubber (SBR), and the thickener, sodium carboxymethyl cellulose, were added to deionized water at a mass ratio of 96.0:1.4:1.5:1.1 and thoroughly mixed to prepare a negative electrode slurry. The negative electrode slurry was then uniformly coated onto the negative electrode current collector copper foil, and subsequently dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0260] At 25°C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7 to obtain a mixed solvent. LiPF6 and fluoroethylene carbonate (FEC) were then dissolved in this mixed solvent to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The mass fraction of FEC was 3%, based on the mass of the electrolyte.

[0261] The positive electrode sheet, separator, and negative electrode sheet are stacked, wound, and hot-pressed in sequence to obtain an electrode assembly. The electrode assembly is then placed in an aluminum-plastic film for top and side sealing. After processes such as electrolyte injection, standing, formation, aging, venting, and secondary sealing, a soft-pack secondary battery cell is obtained.

[0262] Performance testing

[0263] (1) Peel force test between the separator coating and the porous base membrane

[0264] Cut the release liner into three 2.5cm x 15cm strips. Attach the strips to a test steel plate. Use 2cm wide test tape to adhere to the side of the release liner to be tested. Using a tensile testing machine, clamp the steel plate on one side and the tape on the other, perform a 180° peel test. Take the average peel force of the three strips as the peel force between the release liner coating and the porous base membrane. The tensile rate is 50mm / min.

[0265] (2) Thermal shrinkage rate test of the separator film

[0266] The heat shrinkage rate test of the release liner can be referenced in GB / T 36363-2018.

[0267] 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.

[0268] 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.

[0269] 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.

[0270] (3) Tensile strength test of the separator

[0271] The tensile strength test of the separator can be referenced in GB / T 36363-2018.

[0272] The separator membrane samples were made into standard samples, and then subjected to tensile testing using a tensile testing machine until the samples broke. The maximum tensile force obtained was taken as the tensile strength of the separator membrane. The tensile rate was 50 mm / min. The average value of three parallel samples was taken as the test result.

[0273] (4) Puncture strength test of the isolation membrane

[0274] The puncture strength test of the separator can be referenced in GB / T 36363-2018.

[0275] Cut the release liner into strips, with a width greater than 10cm. Place the strips of release liner in the special clamp, ensuring the release liner is flat during placement. Ventilate the clamp to ensure it grips the release liner tightly. Turn on the universal testing instrument and set the needle movement speed to 50mm / min. When the needle punctures the release liner, a reading will appear on the computer screen connected to the universal testing instrument. Take the maximum value as the puncture strength of the release liner. Take 3 points during the test and take the average value as the puncture strength of the release liner.

[0276] (5) Electrolyte wettability test of the separator

[0277] Cut the separator membrane into three 5mm × 100mm strips. Drop 1mL of electrolyte into the center of each strip and let it stand for 2 minutes until the electrolyte stops diffusing. Record the electrolyte diffusion distance as the electrolyte wetting length of the separator membrane. The larger this value, the better the electrolyte wetting of the separator membrane. Take the average value of the three parallel samples as the test result.

[0278] (6) DC resistance (DCR) test of secondary battery cells

[0279] At 25℃, a single secondary battery cell was charged to 4.25V at a constant current rate of 0.33C, then charged at a constant voltage rate to a current of 0.05C, rested for 5 minutes, and then discharged at a constant current rate of 0.33C to 2.8V. The constant current discharge capacity was recorded and denoted as the initial capacity C0. The cell was then rested for 5 minutes, charged to 4.25V at a constant current rate of 0.33C0, then charged at a constant voltage rate to a current of 0.05C, rested for 5 minutes, then discharged at a constant current rate of 0.33C0 for 1.5 hours, rested for 30 minutes, and then discharged at a constant current rate of 3C0 for 30 seconds, rested for 5 minutes. The voltage values ​​before and after the 1.5C0 constant current discharge were recorded as U1 and U2, respectively. The DCR of the secondary battery cell at 50% SOC was calculated using the formula DCR=(U1-U2) / 1.5C0.

[0280] Table 1

[0281] As can be seen from the above test results, the organic polymer particles prepared in this embodiment can give the separator high bonding strength, good heat resistance, high mechanical strength and good electrolyte wettability, and can give the secondary battery cell low DC resistance and good kinetic performance.

[0282] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. An isolation membrane comprising a porous base membrane and a coating on at least one side of the porous base membrane, wherein, The coating includes organic polymer particles containing triazine ring structure units and polar functional groups including one or more of ester groups, carbonyl groups, hydroxyl groups, carboxyl groups, amide groups, sulfonic acid groups, and amino groups.

2. The separator film according to claim 1, wherein The organic polymer particles include bridging structures connecting the triazine ring structure units.

3. The separator film according to claim 2, wherein The bridging structures include one or a combination of two or more of alkylene groups, alkylene ether groups, and alkylene amine groups.

4. The separator film according to any one of claims 1 to 3, wherein The triazine ring structure units further have substituents including one or a combination of two or more of alkyl groups, alkenyl groups, phenyl groups, cycloalkyl groups, amine groups, hydroxyl groups, and halogen groups.

5. The separator film according to any one of claims 1 to 4, wherein The organic polymer particles are melamine formaldehyde polymers.

6. The separator film according to claim 5, wherein The melamine formaldehyde polymers 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, melonitrile-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde, and melonitrile-(2-amino-4-methylamino-1,3,5-triazine) formaldehyde.

7. The separator film according to any one of claims 1 to 6, wherein The organic polymer particles are thermosetting resins; and / or The organic polymer particles are amorphous polymers.

8. The separator film according to any one of claims 1 to 7, wherein The organic polymer particles have no melting point below 300°C.

9. The separator film according to any one of claims 1 to 8, wherein The organic polymer particles have no glass transition temperature below 300°C.

10. The separator membrane according to any one of claims 1 to 9, wherein, The organic polymer 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.

11. The separator film according to any one of claims 1 to 10, wherein The organic polymer 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.

12. The separator film according to any one of claims 1 to 11, wherein The cyclic voltammogram of the organic polymer particles for the first cycle has no oxidation peak in a voltage range of 2.5V to 4.5V.

13. The separator film according to any one of claims 1 to 12, wherein The volume distribution particle size Dv50 of the organic polymer particles is 180nm to 800nm; and / or The true density of the organic polymer particles is 1.1 g / cm 3 -1.7 g / cm 3 .

14. The separator film according to any one of claims 1 to 13, wherein The mass content of the organic polymer particles in the coating is 50% to 99% based on the total mass of the coating; and / or The thickness of the coating is 0.5μm to 5μm; and / or The areal density of the coating is 0.45 g / m 2 - 4.5 g / m 2 .

15. The separator membrane according to any one of claims 1 to 14, wherein, The ratio of the volume distribution particle size Dv50 of the organic polymer particles to the average pore size of the porous base film is 2.5 or more.

16. The separator membrane according to any one of claims 1 to 15, wherein, The separator film satisfies one or more of the following conditions (1) to (6): (1) The peeling force between the coating and the porous base film is 60N / m or more; (2) The longitudinal heat shrinkage of the separator film is 2.0% or less when heated at 130°C for 1h; (3) the release film has a transverse heat shrinkage of less than or equal to 2.0% at 130°C for 1 hour; (4) the release film has a longitudinal tensile strength of 2140 kg / cm or more 2 ; (5) the release film has a transverse tensile strength of 1840 kg / cm or more 2 ; (6) the release film has a puncture strength of greater than or equal to 410 kgf.

17. An organic polymer particle, wherein, The organic polymer particles contain triazine ring structure units and polar functional groups, the polar functional groups including one or more of ester groups, carbonyl groups, hydroxyl groups, carboxyl groups, amide groups, sulfonic acid groups, and amino groups.

18. The organic polymeric particles according to claim 17, wherein, The organic polymer particles include a bridging structure connecting the triazine ring structure units.

19. The organic polymeric particles according to claim 18, wherein, The bridging structure includes one or a combination of two or more of alkylene groups, alkylene ether groups, and alkylene amine groups.

20. The organic polymeric particles according to any one of claims 17-19, wherein, The triazine ring structure units also have substituents, the substituents including a combination of one or more of alkyl groups, alkenyl groups, phenyl groups, cycloalkyl groups, amine groups, hydroxyl groups, and halogen groups.

21. The organic polymeric particles according to any one of claims 17-20, wherein, The organic polymer particles are melamine formaldehyde polymers.

22. The organic polymeric particles according to claim 21, wherein, The melamine formaldehyde polymers 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, trihydrazinotriazine formaldehyde, melamine-(2-amino-4-methylamino-1,3,5-triazine) formaldehyde, and melamine-(2,4-diamino-6-dimethylamino-1,3,5-triazine) formaldehyde.

23. The organic polymer particles according to any one of claims 17-22, wherein, The organic polymer particles are thermosetting resins; and / or, The organic polymer particles are amorphous polymers.

24. The organic polymeric particles according to any one of claims 17 to 23, wherein, The organic polymer particles have no melting point below 300°C.

25. The organic polymeric particles according to any one of claims 17 to 24, wherein, The organic polymer particles have no glass transition temperature below 300°C.

26. The organic polymeric particles according to any one of claims 17 to 25, wherein, The organic polymer 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.

27. The organic polymer particles according to any one of claims 17 to 26, wherein, The organic polymer 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.

28. The organic polymeric particles according to any one of claims 17 to 27, wherein, The cyclic voltammogram of the organic polymer particles in the first cycle has no oxidation peak in a voltage range of 2.5V to 4.5V.

29. The organic polymer particles according to any one of claims 17-28, wherein, The organic polymer particles have a volume distribution particle size Dv50 of 180nm-800nm; and / or, The true density of the organic polymer particles is 1.1 g / cm 3 -1.7 g / cm 3 .

30. A method for preparing organic polymer particles, comprising the following steps: mixing an amine-substituted triazine compound, an aldehyde compound, and a modifier, the modifier having a polar functional group or containing an acid anion that can form a polar functional group, and the polar functional group including one or more of ester groups, carbonyl groups, hydroxyl groups, carboxyl groups, amide groups, sulfonic acid groups, and amino groups, and reacting the mixture in an alkaline environment at a first temperature to obtain a precursor containing triazine ring structures; and The obtained precursor containing a triazine ring structure is heated and cured at a second temperature, and then crushed to obtain organic polymer particles containing a triazine ring structure unit and a polar functional group.

31. The method of claim 30, wherein, The method satisfies one or more of the following conditions (1) to (6): (1) the first temperature is 70°C to 95°C; (2) the reaction time at the first temperature is 8h to 12h; (3) the pH of the basic environment is 8.0 to 9.5; (4) the second temperature is 180°C to 290°C; (5) the heating and curing time at the second temperature is 1h to 8h; (6) the molar ratio of the aldehyde compound to the amine-substituted triazine compound is 1.75:1 to 3:

1.

32. The method of claim 30 or 31, wherein, the mass of the modifier is 0.5% to 3.5% of the total mass of the amine-substituted triazine compound and the aldehyde compound; and / or, the modifier comprises one or more of a polyol, a polyacid, a hydroxy acid, a hydroxyl-containing amide compound, urea, a polyamine, a sulfite, an enol oligomer.

33. The method of any one of claims 30 to 32, wherein, The amine-substituted triazine compounds include one or more of the following general formula 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; and / or, the aldehyde compound comprises one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and furfural.

34. The method of any one of claims 30-33, wherein, the amine-substituted triazine compound comprises 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, trihydrazino-s-triazine, 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.

35. A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator film according to any one of claims 1 to 16, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

36. A battery device comprising a plurality of the secondary battery cells according to claim 35.

37. An electrically powered device comprising the secondary battery cell according to claim 35 or the battery device according to claim 36.

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