Silicon-containing organic resin and manufacturing method therefor, silicon-containing organic resin dispersion liquid, separator, secondary battery cell, battery apparatus, and electrical apparatus

Abstract

Provided in the present disclosure are a silicon-containing organic resin and a manufacturing method therefor, a silicon-containing organic resin dispersion liquid, a separator, a secondary battery cell, a battery apparatus, and an electrical apparatus. The separator comprises a porous base film and a porous coating located on at least one side of the porous base film. The porous coating comprises a silicon-containing organic resin; the silicon-containing organic resin comprises agglomerate particles of primary particles. The secondary battery cell has both high specific energy and good cycle performance.

Description

Silicon-containing organic resin, method for producing the same, silicon-containing organic resin dispersion, separator, secondary battery cell, battery device, and power utilization device

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202411387921.8, filed September 30, 2024, entitled “Silicon-containing organic resin, method for producing the same, silicon-containing organic resin dispersion, separator, secondary battery cell, battery device, and power utilization device,” the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a silicon-containing organic resin, a method for producing the same, a silicon-containing organic resin dispersion, a separator, a secondary battery cell, a battery device, and a power utilization device. BACKGROUND

[0004] As the application range of secondary battery cells is more and more extensive, people’s demand for the use of secondary battery cells is also increasing, for example, the requirements for the energy density, service life and reliability of secondary battery cells are getting higher and higher. Therefore, how to make the secondary battery cell have higher energy density and good service life under the premise of high reliability is a technical problem to be solved at present. SUMMARY

[0005] The present disclosure provides a silicon-containing organic resin, a method for producing the same, a silicon-containing organic resin dispersion, a separator, a secondary battery cell, a battery device, and a power utilization device, which have both high mass energy density and good cycle performance.

[0006] In a first aspect, the present disclosure provides a separator, comprising a porous base film and a porous coating layer located on at least one side of the porous base film, the porous coating layer comprising a silicon-containing organic resin, the silicon-containing organic resin comprising agglomerated particles of primary particles.

[0007] The secondary battery cell using the silicon-containing organic resin with small density can have higher mass energy density. The silicon-containing organic resin of the present disclosure comprises agglomerated particles of primary particles, thereby increasing the size of the whole particles, which is used in the separator, effectively reducing the probability of small particle blocking the pores, and at the same time, can also make the porous coating layer of the separator form more pores, thereby also improving the electrolyte absorption and wettability of the separator, so that the secondary battery cell can have good cycle performance. Therefore, the separator of the present disclosure can make the secondary battery cell have both high mass energy density and good cycle performance.

[0008] In some embodiments, the particle size of the primary particles is 30 nm-250 nm.

[0009] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin is 300 nm-800 nm. The volume distribution particle size Dv50 of the silicon-containing organic resin within the above range is beneficial to the porous base film having good heat resistance and air permeability.

[0010] In some embodiments, the silicon-containing organic resin has no melting point. The silicon-containing organic resin having no melting point indicates that it has good heat resistance and thermal stability, thereby better resisting thermal shrinkage of the porous base film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0011] In some embodiments, the silicon-containing organic resin has no glass transition temperature below 300°C. The silicon-containing organic resin having no glass transition temperature below 300°C indicates that it has good heat resistance and thermal stability, thereby resisting thermal shrinkage of the porous base film, improving the heat resistance of the separator film, and improving the reliability of the secondary battery cell.

[0012] In some embodiments, the silicon-containing organic resin has 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. The silicon-containing organic resin has a low dissolution rate in organic solvents, high structural stability during long-term use of the secondary battery cell, and high chemical stability in electrolyte, thereby enabling the secondary battery cell to have longer cycle stability.

[0013] In some embodiments, the silicon-containing organic resin has 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. The silicon-containing organic resin has a low swelling degree in organic solvents, high structural stability during long-term use of the secondary battery cell, and thereby improves the problem of air permeability decrease of the separator film during use.

[0014] In some embodiments, the cyclic voltammetry curve of the silicon-containing organic resin in the first cycle has no oxidation peak in the voltage range of 2.50V to 4.40V. The silicon-containing organic resin has no oxidation peak in the cyclic voltammetry curve in the first cycle in the voltage range of 2.50V to 4.40V, which indicates that the silicon-containing organic resin is stable in the voltage range of 2.50V to 4.40V. Therefore, the silicon-containing organic resin of the present disclosure has good electrochemical stability, can be applied to high-voltage secondary battery cells, improves the working voltage and energy density of the secondary battery cell, and also enables the secondary battery cell to have good capacity performance characteristics at high voltage.

[0015] In some embodiments, the silicon-containing organic resin has a true density of 1.1 g / cm 3 -1.4 g / cm 3 .

[0016] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic resin contains carbon-carbon bonds and siloxane structures.

[0017] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as a main chain, and side chains containing siloxane structures and benzene ring structures.

[0018] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic crosslinking resin includes a crosslinking structural unit.

[0019] Optionally, the crosslinking structural unit includes one or more of a divinylbenzene structural unit, a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a diallyl maleate structural unit, a ethylene glycol dimethacrylate structural unit, a 1,4-butanediol diacrylate structural unit, a 1,6-hexanediol diacrylate structural unit, a 1,8-octanediol diacrylate structural unit, a trimethylolpropane triacrylate structural unit, a pentaerythritol trimethacrylate structural unit, a tetraethylene glycol dimethacrylate structural unit, a tripropylene glycol diacrylate structural unit, a 2,2,4-trimethyladipoyl bis[2-ethylaziridine] structural unit, a 1,1-nonanedioyl bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structural unit, a trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structural unit, a trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structural unit, and a pentaerythritol tris(3-aziridinyl) propionate structural unit.

[0020] In some embodiments, the mass content of the silicon-containing organic resin in the porous coating is 50%-99% based on the total mass of the porous coating.

[0021] In some embodiments, the thickness of the porous coating is 0.5 μm-5 μm.

[0022] In some embodiments, the heat shrinkage rate of the release film in the longitudinal direction is less than or equal to 1.5% when heated at 130°C for 1 h.

[0023] In some embodiments, the heat shrinkage rate of the release film in the transverse direction is less than or equal to 1.5% when heated at 130°C for 1 h.

[0024] In a second aspect, the present disclosure provides a silicon-containing organic resin, and the silicon-containing organic resin includes agglomerate particles of primary particles.

[0025] In some embodiments, the particle size of the primary particles is 30 nm-250 nm.

[0026] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin is 300-800 nm.

[0027] In some embodiments, the silicon-containing organic resin has no melting point.

[0028] In some embodiments, the silicon-containing organic resin has no glass transition temperature below 300°C.

[0029] In some embodiments, the silicon-containing organic resin has 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.

[0030] In some embodiments, the silicon-containing organic resin has 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.

[0031] In some embodiments, the silicon-containing organic resin has no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.50V to 4.40V.

[0032] In some embodiments, the silicon-containing organic resin has a true density of 1.1 g / cm 3 -1.4 g / cm 3 .

[0033] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic resin contains carbon-carbon bonds and siloxane structures.

[0034] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as the main chain, and the side chains contain siloxane structures and benzene ring structures.

[0035] In some embodiments, the silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic crosslinked resin includes crosslinking structural units.

[0036] Optionally, the crosslinking structure unit comprises one or more of a divinylbenzene structure unit, a diethylene glycol divinyl ether structure unit, a triethylene glycol divinyl ether structure unit, a maleic acid diallyl ester structure unit, a ethylene glycol dimethacrylate structure unit, a 1,4-butanediol diacrylate structure unit, a 1,6-hexanediol diacrylate structure unit, a 1,8-octanediol diacrylate structure unit, a trimethylolpropane triacrylate structure unit, a pentaerythritol trimethacrylate structure unit, a tetraethylene glycol dimethacrylate structure unit, a tripropylene glycol diacrylate structure unit, a 2,2,4-trimethyladipoyl bis[2-ethylaziridine] structure unit, a 1,1-sebacoyl bis[2-methylaziridine] structure unit, a 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structure unit, a trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure unit, a trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure unit, a pentaerythritol tris(3-aziridinyl) propionate structure unit.

[0037] In a third aspect, the present disclosure provides a method for preparing a silicon-containing organic resin, comprising the following steps: providing a pre-emulsion comprising monomers, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomers comprise a silane coupling agent; performing an emulsion polymerization reaction under the conditions of heating, inert gas protection, and stirring; drying the product obtained from the emulsion polymerization reaction; and performing a crushing process and a grinding process to obtain the silicon-containing organic resin.

[0038] In some embodiments, the temperature for drying the product obtained from the emulsion polymerization reaction is 80-150°C.

[0039] In some embodiments, the time for drying the product obtained from the emulsion polymerization reaction is 2-12h.

[0040] In some embodiments, the grinding process comprises the following steps: mixing the material obtained from the crushing process with a solvent, a grinding medium, and optionally a dispersant to obtain a mixed slurry, and then performing a grinding treatment on the mixed slurry to obtain the silicon-containing organic resin.

[0041] Optionally, the solvent comprises one or more of water, methanol, and ethanol.

[0042] Optionally, the dispersant comprises one or more of a polyacrylic acid type dispersant, a carboxymethyl cellulose type dispersant, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0043] Optionally, the grinding medium comprises one or more of zirconia balls, alumina balls, and silicon nitride balls.

[0044] Optionally, the average particle size of the grinding medium is 0.1-2mm.

[0045] Optionally, the filling rate of the grinding medium is 30%-80%.

[0046] Optionally, the rotation speed of the grinding is 500rpm-3000rpm.

[0047] In some embodiments, the heating temperature of the maturation stage of the emulsion polymerization reaction is 70℃-95℃.

[0048] In some embodiments, the heating time of the maturation stage of the emulsion polymerization reaction is 1h-5h.

[0049] In some embodiments, the inert gas comprises one or more of nitrogen, argon, and helium.

[0050] In some embodiments, the emulsion polymerization reaction comprises the following steps: dropping the pre-emulsion into a reactor containing water under the conditions of a first temperature, inert gas protection, and stirring, and after a first time, increasing the temperature to the heating temperature of the maturation stage to perform the maturation reaction to obtain the silicon-containing organic resin.

[0051] In some embodiments, the first temperature is 55℃-70℃.

[0052] In some embodiments, the first time is 3h-6h.

[0053] In some embodiments, the silane coupling agent includes alkenyl and / or acryloxy, optionally including one or more of gamma-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, gamma-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltri(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(beta-methoxyethoxy)silane, ethylene tris[(1-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyl dimethyl ethoxysilane, methylethyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylethyldimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0054] In some embodiments, the crosslinking agent includes one or more of divinylbenzene, diethylene glycol divinyl ether, triethylene glycol divinyl ether, maleic acid diallyl ester, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropylene glycol diacrylate, 2,2,4-trimethylhexanedioic acid bis[2-ethylaziridine], 1,1-nonanedioic acid bis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-1-aziridinylpropionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate.

[0055] In some embodiments, the mass fraction of the crosslinking agent is 1.5-18% based on the total mass of the monomer and the crosslinking agent being 100%.

[0056] In a fourth aspect, the present disclosure provides a silicon-containing organic resin dispersion liquid including the silicon-containing organic resin of the second aspect and a dispersant, or obtained by the method of the third aspect.

[0057] In a fifth aspect, the present disclosure provides a secondary battery cell including a positive electrode sheet, a negative electrode sheet, and the separator of the first aspect of the present disclosure, the separator being disposed between the positive electrode sheet and the negative electrode sheet.

[0058] In a sixth aspect, the present disclosure provides a battery device including a plurality of the secondary battery cell of the fifth aspect of the present disclosure.

[0059] In a seventh aspect, the present disclosure provides an electric device including the secondary battery cell of the fifth aspect of the present disclosure or the battery device of the sixth aspect of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments of the present disclosure will be briefly introduced below. Obviously, the drawings described below are only some of the embodiments of the present disclosure, and other drawings can be obtained by those of ordinary skill in the art without creative labor on the basis of the drawings.

[0061] FIG. 1 shows a schematic diagram of a secondary battery cell according to some embodiments of the present disclosure.

[0062] FIG. 2 shows a schematic diagram of an electric device according to some embodiments of the present disclosure.

[0063] FIG. 3 shows a scanning electron microscope image of a silicon-containing organic resin prepared in Example 1. DETAILED DESCRIPTION

[0064] Hereinafter, specific embodiments of the silicon-containing organic resin and the method for producing the same, the silicon-containing organic resin dispersion, 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, 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.

[0065] The ranges disclosed herein are defined by their lower and upper endpoints, given that a range is defined by selecting a lower endpoint and an upper endpoint, the selected lower and upper endpoints define the boundaries of the particular range. Ranges defined by endpoints can be either inclusive or exclusive of the endpoints, and can be arbitrarily combined, i.e., any lower endpoint can be combined with any upper endpoint to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Also, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all of the individual real combinations that fall between "a" and "b", where "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand way of describing those numerical combinations. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0066] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0067] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present disclosure.

[0068] Unless otherwise specified, all steps of the present disclosure can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0069] Unless otherwise specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects, and are not used to describe a particular order or primary and secondary relationship.

[0070] In the present disclosure, the terms "a plurality of", "a plurality of" refer to two or more.

[0071] In the description of the embodiments of the present disclosure, if there is no special indication, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "below", "under" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0072] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25°C.

[0073] 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.

[0074] The secondary battery cell provided by the embodiments of the present disclosure can include but is not limited to lithium battery cells, sodium battery cells, such as lithium ion battery cells, sodium ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0075] The secondary battery cell provided by the embodiments of the present disclosure includes an electrode assembly. The electrode assembly can be a winding structure or a stacking structure, which is not limited in the embodiments of the present disclosure. The secondary battery cell further includes an outer package, which can be used to package the electrode assembly. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

[0076] The battery apparatus mentioned in the embodiments of the present disclosure can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of secondary battery cells connected in series, in parallel or in a mixed manner through a busbar component.

[0077] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of secondary battery cells.

[0078] As an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of secondary battery cells.

[0079] In some embodiments, the battery device can be a battery pack, which includes a case and one or more battery cell assemblies, the battery cell assemblies being accommodated in the case.

[0080] As an example, the battery cell assembly can be a battery module, which can be accommodated in the case by fixing the battery module in the case.

[0081] As an example, the battery cell assembly can also be accommodated in the case by directly fixing a plurality of secondary battery cells in the case.

[0082] As an example, the case can include a first case and a second case. The first case and the second case are fastened so that an enclosed space is formed inside the case to accommodate the battery cell assembly. Here, the enclosed means covered or closed, which can be sealed or unsealed. The first case can be a top cover or a bottom plate.

[0083] As an example, the case can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are connected to the frame, respectively, so that an enclosed space is formed inside the case to accommodate the battery cell assembly.

[0084] In some embodiments, the case can be part of a chassis structure of a vehicle. For example, part of the case can be at least part of a floor of the vehicle, or part of the case can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0085] The technical solutions described in the embodiments of the present disclosure are applicable to various electric devices using secondary battery cells and battery devices, such as mobile devices (e.g., mobile phones, tablet computers, notebook computers, 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. The secondary battery cells and the battery devices are used to store or provide electric energy.

[0086] FIG. 2 is a schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0087] In the context of the present disclosure, the silicon-containing organic resin mainly plays a role in improving heat resistance in the porous coating of the separator film, and has little adhesion effect.

[0088] The separator film is an important component for supporting the secondary battery cell to complete the charge-discharge electrochemical process. The commonly used separator film is mostly polyolefin material, but the heat resistance of the polyolefin material is poor, which is easy to soften or melt at high temperature, thereby causing short circuit of the secondary battery cell. In order to improve the heat resistance of the separator film, a porous coating layer is usually coated on the separator film to improve the heat resistance of the separator film. Boehmite, alumina and other inorganic particles are currently commonly used heat-resistant fillers, but the density of such heat-resistant fillers is large, and the mass is large under the same packing volume, thereby affecting the energy density of the secondary battery cell.

[0089] Based on this, the embodiment of the present disclosure provides a silicon-containing organic resin which is used in a separator film, and can make the secondary battery cell have high mass energy density and good cycle performance.

[0090] The silicon-containing organic resin of the present disclosure includes agglomerated particles of primary particles.

[0091] Generally, the agglomerated particles of primary particles can also be referred to as secondary particles.

[0092] The silicon-containing organic resin has small density, and the secondary battery cell using the same can have higher mass energy density. The silicon-containing organic resin of the present disclosure includes agglomerated particles of primary particles, thereby increasing the size of the whole particles, which is used in the separator film, effectively reduces the probability of small particles blocking the pores, and at the same time, can also make the porous coating layer of the separator film form more pores, thereby also improving the electrolyte absorption and wettability of the separator film, so that the secondary battery cell can have good cycle performance. Therefore, the silicon-containing organic resin of the present disclosure is used in the separator film, and can make the secondary battery cell have high mass energy density and good cycle performance.

[0093] In some embodiments, the true density of the silicon-containing organic resin can be 1.1 g / cm 3 -1.4 g / cm 3 .

[0094] At present, the true density of boehmite, alumina and other inorganic particles is usually 2.5 g / cm 3 -3.5 g / cm 3 . The true density of the silicon-containing organic resin of the present disclosure is small, thereby making the secondary battery cell using the separator film of the present disclosure have higher mass energy density.

[0095] The silicon-containing organic resin of the present disclosure includes agglomerate particles of primary particles. In some embodiments, the primary particles can have a particle size of 30 nm-250 nm. Alternatively, the primary particles can have a particle size of 30 nm-240 nm, 30 nm-220 nm, 30 nm-200 nm, 30 nm-180 nm, 30 nm-160 nm, 30 nm-150 nm, 50 nm-240 nm, 50 nm-220 nm, 50 nm-200 nm, 50 nm-180 nm, 50 nm-160 nm, 50 nm-150 nm, 80 nm-240 nm, 80 nm-220 nm, 80 nm-200 nm, 80 nm-180 nm, 80 nm-160 nm, 80 nm-150 nm, 85 nm-240 nm, 85 nm-220 nm, 85 nm-200 nm, 85 nm-180 nm, 85 nm-160 nm, 85 nm-150 nm, 90 nm-240 nm, 90 nm-220 nm, 90 nm-200 nm, 90 nm-180 nm, 90 nm-160 nm, 90 nm-150 nm.

[0096] The particle size of the primary particles can be tested by the following method: the silicon-containing organic resin particle powder is laid and adhered on a conductive glue to form a sample to be tested with a length x width of 6 cm x 1.1 cm; the particle morphology is tested using a scanning electron microscope (e.g., ZEISS Sigma 300), and the test can refer to JY / T010-1996. The particle size of the primary particles is measured in the scanning electron microscope image of the test.

[0097] In some embodiments, the volume distribution particle size Dv50 of the silicon-containing organic resin can be 300 nm-800 nm, for example, can be 300 nm, 320 nm, 360 nm, 400 nm, 440 nm, 480 nm, 520 nm, 560 nm, 600 nm, 640 nm, 680 nm, 720 nm, 760 nm, 780 nm, or a range consisting of any of the above values.

[0098] The volume distribution particle size Dv50 of the silicon-containing organic resin in the above range is beneficial to the isolation film having good heat resistance and air permeability.

[0099] Alternatively, the volume distribution particle size Dv50 of the silicon-containing organic resin can be 320 nm-800 nm, 360 nm-800 nm, 400 nm-800 nm, 320 nm-760 nm, 360 nm-760 nm, 400 nm-760 nm, 320 nm-720 nm, 360 nm-720 nm, 400 nm-720 nm.

[0100] Dv50 represents the particle size corresponding to the cumulative volume distribution percentage of 50%, which can be tested by a laser particle size analyzer according to GB / T 19077-2016. During the test, 1 g of the sample to be tested is added to a clean small beaker, 20 ml of deionized water is added, and ultrasonic treatment is performed at 53 KHz / 120 W for 5 min to ensure that the sample is completely dispersed. After the light path system is cleaned, the background is automatically tested. The solution to be tested is stirred to make it uniformly dispersed, and then placed in the sample cell according to the requirements, and the particle size is measured. The testing instrument can be a MasterSizer 3000 laser particle size analyzer.

[0101] In some embodiments, the number percentage of the agglomerate particles in the silicon-containing organic resin can be greater than 50%, and can be greater than or equal to 60%, greater than or equal to 70%.

[0102] The number percentage of the agglomerate particles in the silicon-containing organic resin can be tested by the following method: the silicon-containing organic resin particle powder is laid and adhered on the conductive glue to form a sample to be tested with a length of 6 cm and a width of 1.1 cm. A scanning electron microscope (such as ZEISS Sigma 300) is used to test the particle morphology, and the test can refer to JY / T010-1996. In order to ensure the accuracy of the test results, a plurality of (for example, 20) different regions are randomly selected from the sample to be tested for scanning test, and the percentage of the number of agglomerate particles in each region to the total number of particles is calculated under a certain magnification, that is, the number percentage of the agglomerate particles in the region. The average value of the test results of a plurality of test regions is taken as the number percentage of the agglomerate particles in the silicon-containing organic resin.

[0103] The silicon-containing organic resin of the present disclosure is neither soluble in water nor in organic solvents such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), chloroform at 25°C, i.e. not soluble in the mobile phase for gel permeation chromatography test, and the molecular weight of the silicon-containing organic resin cannot be tested by gel permeation chromatography.

[0104] In some embodiments, the silicon-containing organic resin is a silicon-containing organic cross-linked resin, and the silicon-containing organic cross-linked resin contains carbon-carbon bonds and siloxane structures.

[0105] Alternatively, the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as the main chain, and the side chain contains siloxane structures.

[0106] Alternatively, the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as the main chain, and the side chain contains siloxane structures and benzene ring structures.

[0107] In some embodiments, the silicon-containing organic resin is a silicon-containing organic cross-linked resin, and the silicon-containing organic cross-linked resin includes cross-linked structural units.

[0108] The crosslinking structural unit of the silicon-containing organic crosslinking resin refers to a non-silicon-containing structural unit used to connect the silicon-containing structural units.

[0109] In some embodiments, the crosslinking structural unit can include one or more of a divinylbenzene structural unit, a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a maleic acid diallyl ester structural unit, an ethylene glycol dimethacrylate structural unit, a 1,4-butanediol diacrylate structural unit, a 1,6-hexanediol diacrylate structural unit, a 1,8-octanediol diacrylate structural unit, a trimethylolpropane triacrylate structural unit, a pentaerythritol trimethacrylate structural unit, a tetraethylene glycol dimethacrylate structural unit, a tripropylene glycol diacrylate structural unit, a 2,2,4-trimethyl adipic acid bis[2-ethylaziridine] structural unit, a 1,1-sebacic acid bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structural unit, a trimethylolpropane tris(2-methyl-l-aziridinyl propionate) structural unit, a trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structural unit, a pentaerythritol tris(3-aziridinyl) propionate structural unit.

[0110] Optionally, the crosslinking structural unit can include a divinylbenzene structural unit.

[0111] Optionally, the crosslinking structural unit can include a divinylbenzene structural unit and one or more of a diethylene glycol divinyl ether structural unit, a triethylene glycol divinyl ether structural unit, a maleic acid diallyl ester structural unit, an ethylene glycol dimethacrylate structural unit, a 1,4-butanediol diacrylate structural unit, a 1,6-hexanediol diacrylate structural unit, a 1,8-octanediol diacrylate structural unit, a trimethylolpropane triacrylate structural unit, a pentaerythritol trimethacrylate structural unit, a tetraethylene glycol dimethacrylate structural unit, a tripropylene glycol diacrylate structural unit, a 2,2,4-trimethyl adipic acid bis[2-ethylaziridine] structural unit, a 1,1-sebacic acid bis[2-methylaziridine] structural unit, a 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structural unit, a trimethylolpropane tris(2-methyl-l-aziridinyl propionate) structural unit, a trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structural unit, a pentaerythritol tris(3-aziridinyl) propionate structural unit.

[0112] In some embodiments, the silicon-containing organic resin has no melting point.

[0113] The silicon-containing organic resin has no melting point, indicating that it has good heat resistance and thermal stability, and thus can better resist thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0114] The melting point can be tested as follows: take an appropriate amount of sample (e.g., 5-15 mg) and place it in a differential scanning calorimeter (DSC) crucible, shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; program settings: temperature rise from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, temperature drop from 200°C to -40°C at a rate of 10°C / min, and temperature rise from -40°C to 300°C at a rate of 10°C / min. Whether the silicon-containing organic resin has a melting point below 300°C is determined by the DSC curve. The silicon-containing organic resin has no melting point means that the DSC curve of the silicon-containing organic resin has no melting peak.

[0115] In some embodiments, the silicon-containing organic resin has no glass transition temperature below 300°C.

[0116] The silicon-containing organic resin has no glass transition temperature below 300°C, indicating that it has good heat resistance and thermal stability, and thus can resist thermal shrinkage of the porous base film, improve the heat resistance of the separator film, and improve the reliability of the secondary battery cell.

[0117] The glass transition temperature T g The melting point can be tested as follows: take an appropriate amount of sample (e.g., 5-15 mg) and place it in a differential scanning calorimeter (DSC) crucible, shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; program settings: temperature rise from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, temperature drop from 200°C to -40°C at a rate of 10°C / min, and temperature rise from -40°C to 300°C at a rate of 10°C / min. Whether the silicon-containing organic resin has a melting point below 300°C is determined by the DSC curve. The silicon-containing organic resin has no melting point means that the DSC curve of the silicon-containing organic resin has no melting peak. g .

[0118] The glass transition temperature T g is the transition temperature from the glassy state to the high-elastic state, which shows a step change on the DSC curve.

[0119] The silicon-containing organic resin has no glass transition temperature T g below 300°C means that the DSC curve of the silicon-containing organic resin does not show a step change below 300°C.

[0120] In some embodiments, the silicon-containing organic resin has 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.

[0121] The silicon-containing organic resin has a low dissolution rate in an organic solvent, high structural stability during long-term use of the secondary battery cell, and high chemical stability in the electrolyte, thereby providing the secondary battery cell with longer cycle stability.

[0122] The dissolution rate of the silicon-containing organic resin can be tested by the following method: taking an appropriate amount of sample (e.g., about 1 g) and weighing it as m1, placing it in a semi-permeable membrane sample bag, sealing the bag, recording the total mass of the sample bag m2, and immersing the sample bag in an appropriate amount of solvent (e.g., about 50 g) at 60°C for 7 days. Then, the sample bag is removed, drained, and dried, and the total mass of the sample bag is weighed again as m3. The dissolution rate is (m2-m3) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0123] In some embodiments, the silicon-containing organic resin has 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.

[0124] The silicon-containing organic resin has a low swelling degree in an organic solvent, high structural stability during long-term use of the secondary battery cell, and thereby improves the problem of decreased air permeability of the separator during use.

[0125] The swelling degree of the silicon-containing organic resin can be tested by the following method: taking an appropriate amount of sample (e.g., about 1 g) and weighing it as m1, placing it in a semi-permeable membrane sample bag, sealing the bag, and immersing the sample bag in an appropriate amount of solvent (e.g., about 50 g) at 60°C for 7 days. Then, the sample bag is removed, and the sample is removed from the sample bag, excess solvent is wiped off, and the mass of the sample is weighed again as m2. The swelling degree is (m2-m1) / m1 x 100%. The solvent is a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0126] In some embodiments, the silicon-containing organic resin has no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.50V to 4.40V.

[0127] The cyclic voltammogram of the silicon-containing organic resin in the first cycle has no oxidation peak in the voltage range of 2.50V to 4.40V, which indicates that the silicon-containing organic resin is stable in the voltage range of 2.50V to 4.40V. Therefore, the silicon-containing organic resin of the present disclosure has good electrochemical stability, can be applied in high-voltage secondary battery cells, improves the working voltage and energy density of the secondary battery cells, and also enables the secondary battery cells to have good capacity performance characteristics at high voltage.

[0128] The oxidation peak potential of the cyclic voltammogram of the silicon-containing organic resin can be tested by the following method: taking the silicon-containing organic resin, the binder polyacrylate, and the conductive agent conductive carbon black, dissolving them in water according to a solid content mass ratio of 64:7:29 to prepare a slurry, coating the slurry on an aluminum foil as a positive electrode, taking a lithium foil as a negative electrode, and assembling a coin cell. The coin cell is subjected to cyclic voltammetry (CV) test, the scanning rate is 0.10mV / s, the voltage range is 2.50V-5.00V, and the cycle is 3 cycles. The voltage corresponding to the peak point of the first cycle cyclic voltammogram is taken as the oxidation peak potential. The electrolyte salt of the electrolyte used for testing is LiPF6, and the concentration is 1mol / L. The solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) according to a volume ratio of 3:7.

[0129] The present disclosure also provides a preparation method of the silicon-containing organic resin.

[0130] The preparation method of the silicon-containing organic resin comprises the following steps: providing a pre-emulsion containing monomers, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomers comprise a silane coupling agent; and performing emulsion polymerization under the conditions of heating, inert gas protection, and stirring; drying the product obtained by the emulsion polymerization; and then performing a crushing process and a grinding process to obtain the silicon-containing organic resin.

[0131] After the product obtained by the emulsion polymerization is dried, the silicon-containing organic resin will be aggregated to form an aggregate particle of primary particles.

[0132] In some embodiments, the drying method for the product obtained by the emulsion polymerization can include, but is not limited to, vacuum drying, spray drying, air blowing drying, microwave drying, or fluidized bed drying.

[0133] In some embodiments, the temperature for drying the product obtained by the emulsion polymerization can be 80℃-150℃, for example, can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, or a range formed by any of the above values.

[0134] In some embodiments, the time for drying the product obtained from the emulsion polymerization reaction can be 2h-12h, for example, can be 2h, 2.4h, 2.8h, 3.2h, 3.6h, 4h, 4.4h, 4.8h, 5.2h, 5.6h, 6h, 6.4h, 6.8h, 7.2h, 7.6h, 8h, 8.4h, 8.8h, 9.2h, 9.6h, 10h, 10.4h, 10.8h, 11.2h, 11.6h, 12h, or a range formed by any of the above values.

[0135] In some embodiments, the crushing process can employ an air jet mill, a vibration mill, a mechanical crusher, an ultrasonic crusher, a ball mill, etc.

[0136] In some embodiments, the grinding process can include the following steps: mixing the material subjected to the crushing process with a solvent, a grinding medium, and an optional dispersant to obtain a mixed slurry, and then subjecting the mixed slurry to a grinding process to obtain a silicon-containing organic resin.

[0137] Optionally, the solvent can include one or more of water, methanol, ethanol. More optionally, the solvent can include water.

[0138] Optionally, the dispersant can include one or more of a polyacrylic acid type dispersant, a carboxymethyl cellulose type dispersant, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone. Optionally, the polyacrylic acid type dispersant can include one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, ammonium acrylate. Optionally, the carboxymethyl cellulose type dispersant can include one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose.

[0139] Optionally, the grinding medium can include one or more of zirconia balls, alumina balls, silicon nitride balls.

[0140] Optionally, the average particle size of the grinding medium can be 0.1mm-2mm.

[0141] Optionally, the filling rate of the grinding medium can be 30%-80%. In this way, the grinding medium can be in sufficient contact with the silicon-containing organic resin, and the grinding process effect can be improved.

[0142] Optionally, the rotation speed of the grinding can be 500 rpm-3000 rpm, for example, can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, 3000 rpm, or a range consisting of any of the above values.

[0143] In some embodiments, the heating temperature of the maturation stage of the emulsion polymerization reaction can be 70℃-95℃, for example, can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, or a range consisting of any of the above values.

[0144] In some embodiments, the heating time of the maturation stage of the emulsion polymerization reaction can be 1h-5h, for example, can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h, 5h, or a range consisting of any of the above values.

[0145] In some embodiments, the inert gas can include one or more of nitrogen, argon, helium.

[0146] In some embodiments, the emulsion polymerization reaction can include the following steps: dropping the pre-emulsion into a reactor containing water under the conditions of a first temperature, inert gas protection and stirring, and after a first time, heating to the heating temperature of the maturation stage to carry out the maturation reaction to obtain a silicon-containing organic resin.

[0147] In some embodiments, the first temperature can be 55℃-70℃.

[0148] In some embodiments, the first time can be 3h-6h.

[0149] The crosslinking agent forms a crosslinking structural unit of the silicon-containing organic crosslinked resin after polymerization with the monomer.

[0150] In some embodiments, the crosslinking agent can be a multifunctional crosslinking agent.

[0151] Optionally, the crosslinking agent can include one or more of divinylbenzene, diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, dipentaerythritol diacrylate, 2,2,4-trimethyladipolyl di[2-ethylaziridine], 1,1-nonanedioyl di[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)di[2-methylaziridine], trimethylolpropane tri(2-methyl-1-aziridinyl propionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tri(3-aziridinyl)propionate.

[0152] Optionally, the crosslinking agent can include divinylbenzene.

[0153] Optionally, the crosslinking agent can include divinylbenzene and one or more of diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, dipentaerythritol diacrylate, 2,2,4-trimethyladipolyl di[2-ethylaziridine], 1,1-nonanedioyl di[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)di[2-methylaziridine], trimethylolpropane tri(2-methyl-1-aziridinyl propionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tri(3-aziridinyl)propionate.

[0154] In some embodiments, the silane coupling agent can include an alkenyl group and / or an acryloxy group.

[0155] The silane coupling agent includes an alkenyl group and / or an acryloxy group, which can initiate the generation of free radicals between the monomers, crosslinking reactions occur, and the monomers also crosslink with the crosslinking agent, thereby forming a three-dimensional network molecular structure of the silicon-containing organic resin, which is not easy to soften or deform at high temperatures, and has high heat resistance.

[0156] Optionally, the silane coupling agent can include a vinylsilane coupling agent and / or an acryloxy silane coupling agent.

[0157] Optionally, the silane coupling agent can include one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltris(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(β-methoxyethoxy)silane, ethylene tris[(1-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyl dimethyl ethoxysilane, methylvinyl diethoxysilane, vinylmethyl dimethoxysilane, vinylmethyl diethoxysilane, methylvinyl dimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0158] In some embodiments, the mass fraction of the crosslinking agent can be 1.5% to 18%, for example, can be 1.5%, 3%, 4%, 5%, 6%, 7%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 16%, 17%, 18%, or a range consisting of any of the aforementioned values, based on 100% of the total mass of the monomer and the crosslinking agent.

[0159] The mass fraction of the crosslinking agent in the above range can obtain a silicon-containing organic resin with good heat resistance.

[0160] Optionally, the mass fraction of the crosslinking agent can be 4% to 18%, 6% to 18%, 8% to 18%, 4% to 16%, 6% to 16%, 8% to 16%, 4% to 15%, 6% to 15%, 8% to 15%.

[0161] In some embodiments, the emulsifier can include, but is not limited to, one or more of alkyl sulfate, alkyl sulfonate, Tween emulsifier, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, cetyl stearyl alcohol polyether, oleyl alcohol polyether. Alternatively, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, laureth-7, laureth-9, laureth-10, oleyl alcohol polyether-10.

[0162] In some embodiments, the initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutylimidazole hydrochloride, azobisisopropylimidazole.

[0163] In some embodiments, the mass fraction of the initiator can be 0.15%-2.5%, for example, can be 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, or a range consisting of any of the above values, based on 100% of the total mass of the monomer and the crosslinking agent.

[0164] Alternatively, the mass fraction of the initiator can be 0.3%-2.1%, 0.3%-1.9%, 0.3%-1.7%, 0.3%-1.5%, 0.3%-1.3%.

[0165] In some embodiments, the pre-emulsion can further include a pH adjuster. Alternatively, the pH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia water, etc.

[0166] The present disclosure further provides a silicon-containing organic resin dispersion liquid, which includes the above-mentioned silicon-containing organic resin and a dispersant, or is obtained by the preparation method of the silicon-containing organic resin of the present disclosure.

[0167] The present disclosure further provides an isolation membrane.

[0168] The isolation membrane includes a porous base film and a porous coating layer on at least one side of the porous base film, and the porous coating layer includes a binder and the silicon-containing organic resin of the present disclosure or the silicon-containing organic resin prepared by the method of the present disclosure.

[0169] Both the porous base film and the porous coating layer have a pore structure, so that the isolation membrane has good air permeability and facilitates ion passage. The silicon-containing organic resins in the porous coating layer are connected to each other and fixed by the binder, and the gaps between the silicon-containing organic resins can form a pore structure.

[0170] In some embodiments, the mass content of the silicon-containing organic resin in the porous coating can be 50%-99% based on the total mass of the porous coating.

[0171] Optionally, the mass content of the silicon-containing organic resin in the porous coating can be 60%-99%, 70%-99%, 80%-99%, 85%-99%, 88%-99%, 80%-97%, 85%-97%, 88%-97%, 80%-95%, 85%-95%, 88%-95%.

[0172] In some embodiments, the binder in the porous coating can include, but is not limited to, one or more of polyacrylate-based binders, nitrile rubber-based binders, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0173] In some embodiments, the porous coating can further include a dispersant, which can include, but is not limited to, polyacrylate-based dispersants or carboxymethyl cellulose-based dispersants. As an example, the dispersant can include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, ammonium polyacrylate.

[0174] In some embodiments, the separator film can further include polymeric binder particles.

[0175] The "polymeric binder particles" in the porous coating of the separator film play a role in improving the adhesion of the separator film to the pole piece, and have substantially no high-temperature resistance.

[0176] In some embodiments, the polymeric binder particles can be embedded in the silicon-containing organic resin and form protrusions on the surface of the porous coating.

[0177] In other embodiments, the porous coating of the separator film includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on the porous base film, the bonding layer is disposed on at least a portion of the surface of the heat-resistant layer away from the porous base film, the silicon-containing organic resin is disposed in the heat-resistant layer, and the polymeric binder particles are disposed in the bonding layer.

[0178] In yet other embodiments, the porous coating of the separator film includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a portion of the surface of the other side of the porous base film, the silicon-containing organic resin is disposed in the heat-resistant layer, and the polymeric binder particles are disposed in the bonding layer.

[0179] In some embodiments, the average particle size of the polymeric binder particles can be 6-18 μm.

[0180] In some embodiments, the polymeric binder particles can include vinylidene fluoride-based polymeric particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomers and comonomers.

[0181] The comonomer can include at least one of an olefin monomer, a fluorine-containing olefin monomer, a chlorine-containing olefin monomer, an acrylate monomer, an acrylic monomer, and a fluorine ether monomer.

[0182] Optionally, the comonomer can include at least one of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ether (e.g., perfluoro(methyl vinyl) ether, perfluoro(ethyl vinyl) ether, perfluoro(propyl vinyl) ether), perfluoro(1,3-dioxolane), and perfluoro(2,2-dimethyl-1,3-dioxolane).

[0183] In some embodiments, the porous coating layer can have a thickness of 0.5 μm to 5 μm. The thickness of the porous coating layer refers to the thickness of the porous coating layer on one side of the porous base film. Optionally, the thickness of the porous coating layer can be 0.5 μm to 4 μm, 0.5 μm to 3 μm, 0.5 μm to 2 μm, 0.6 μm to 4 μm, 0.6 μm to 3 μm, 0.6 μm to 2 μm, 0.8 μm to 4 μm, 0.8 μm to 3 μm, 0.8 μm to 2 μm.

[0184] In some embodiments, the porous base film can include a film or nonwoven web selected from any one or at least two of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyether sulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, and polyvinyl naphthalene.

[0185] The porous base film can be a single-layer film or a multi-layer composite film. When the porous base film is a multi-layer composite film, the materials of the layers can be the same or different.

[0186] In some embodiments, the porous base film can have a thickness of 4 μm to 12 μm, and optionally 4 μm to 9 μm.

[0187] In some embodiments, the porous base film can have a porosity of 25% to 60%, and optionally 28% to 50%.

[0188] In some embodiments, the separator film can have a thickness of 5 μm to 14 μm, and optionally 5 μm to 12 μm, 6 μm to 12 μm. This is advantageous for improving the energy density of the secondary battery cell.

[0189] In some embodiments, the heat shrinkage rate of the isolation film in the machine direction (MD) can be less than or equal to 1.5% when heated at 130°C for 1 hour.

[0190] In some embodiments, the heat shrinkage rate of the isolation film in the transverse direction (TD) can be less than or equal to 1.5% when heated at 130°C for 1 hour.

[0191] It should be noted that the porous coating parameters of the isolation film described above are the porous coating parameters of one side of the porous base film. When the porous coating is arranged on both sides of the porous base film, as long as the porous coating parameters of any one side meet the present disclosure, it is considered to fall within the protection scope of the present disclosure.

[0192] The isolation film can be prepared according to methods known in the art.

[0193] In some embodiments, a slurry including the silicon-containing organic resin and the binder can be coated on at least one side of the porous base film, and after drying, the isolation film is obtained.

[0194] In some embodiments, the slurry can further include polymer binder particles, and after drying of the slurry, the polymer binder particles are embedded in the silicon-containing organic resin and form protrusions on the surface of the porous coating.

[0195] In some embodiments, the method for preparing the isolation film can include the steps of: coating a heat-resistant layer slurry including the silicon-containing organic resin and the binder on at least one side of the porous base film, and after drying, forming a heat-resistant layer; and coating an adhesive layer slurry including the polymer binder particles and the binder on at least a part of the surface of the heat-resistant layer, and after drying, obtaining the isolation film.

[0196] In some embodiments, the method for preparing the isolation film can include the steps of: coating a heat-resistant slurry including the silicon-containing organic resin and the binder on one side of the porous base film, and coating an adhesive layer slurry including the polymer binder particles and the binder on at least a part of the surface of the other side of the porous base film, and after drying, obtaining the isolation film.

[0197] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0198] In some embodiments, the slurry can further include other components, for example, can further include a dispersant and / or a wetting agent, etc.

[0199] The embodiments of the present disclosure also provide a secondary battery cell. The secondary battery cell includes the isolation film provided by the embodiments of the present disclosure.

[0200] The secondary battery cell further includes a positive electrode sheet, a negative electrode sheet, and an electrolyte, and the isolation film is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the isolation film, and the negative electrode sheet can form an electrode assembly through a rolling process and / or a stacking process.

[0201] The secondary battery cell provided by the present disclosure can include, but is not limited to, a lithium battery cell, a sodium battery cell, etc., and the type of the secondary battery cell is different, and the composition of the positive electrode tab, the negative electrode tab, and the electrolyte will be different.

[0202] [Positive electrode tab]

[0203] In some embodiments, the positive electrode tab can include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite in the thickness direction of itself, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0204] Taking a lithium battery cell as an example, the positive electrode active material can include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides can include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon, and their respective modified compounds. In some embodiments, in order to further improve the energy density of the secondary battery cell, the positive electrode active material can include one or more of lithium transition metal oxides of the general formula LiaNibCocMdOeAf 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.

[0205] As an example, the positive electrode active material can include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1O2(NCM811), LiNi 0.85 Co 0.1 Al 0.05 O2, LiFePO4, LiMnPO4.

[0206] The secondary battery cell will be accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the secondary battery cell is discharged to different states. In the enumeration of the positive active material in the present disclosure, the molar content of Li is the initial state of the material, i.e. the state before feeding, and the positive active material is applied to the secondary battery cell. After charging and discharging cycle, the molar content of Li will change. In the enumeration of the positive active material in the present disclosure, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will also appear to float.

[0207] Taking a sodium battery cell as an example, the positive active material can include but is not limited to one or more of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), prussian blue type materials. As an example, the positive active material can include but is not limited to NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, prussian blue type materials, and materials of the general formula XpM’q(PO4)rOxY3-x. In the general formula XpM’q(PO4)rOxY3-x, 0

[0208] The modified compounds of the positive active materials of the above lithium battery cells and sodium battery cells can be doped modification and / or surface coating modification of the positive active materials.

[0209] In some embodiments, the positive electrode film layer can further include a positive electrode conductive agent. As an example, the positive electrode conductive agent can include, but is not limited to, one or more of super-P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0210] In some embodiments, the positive electrode film layer can further include a positive electrode binder. As an example, the positive electrode binder can include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic resin.

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

[0212] The positive electrode film layer is typically formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is typically formed by dispersing and uniformly stirring a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and any other components in a solvent. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0213] [Negative electrode tab]

[0214] In some embodiments, the negative electrode tab can include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite in the thickness direction of itself, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0215] The negative electrode active material can employ a material known in the art that can be used for a secondary battery cell. As an example, the negative electrode active material can include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material can include, but is not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and a silicon alloy material. The tin-based material can include, but is not limited to, one or more of elemental tin, tin oxide, and a tin alloy material.

[0216] In some embodiments, the negative electrode film layer can further include a negative electrode conductive agent. As an example, the negative electrode conductive agent can include, but is not limited to, one or more of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0217] In some embodiments, the negative electrode film layer can further include a negative electrode binder. As an example, the negative electrode binder can include, but is not limited to, one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0218] In some embodiments, the negative electrode film layer can further include other auxiliary agents. As an example, the other auxiliary agents can include thickening agents, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0219] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0220] The negative electrode film layer is typically formed by coating a negative electrode slurry on a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing and uniformly stirring a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and other optional auxiliary agents in a solvent. The solvent can be N-methyl pyrrolidone (NMP) or deionized water, but is not limited thereto.

[0221] The negative electrode tab does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode tab further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) interposed between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0222] In some embodiments, the negative electrode tab can use a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, or the like. When the foamed metal is used as the negative electrode tab, the surface of the foamed metal can not be provided with a negative electrode active material, and of course, can be provided with a negative electrode active material.

[0223] [Electrolyte]

[0224] The electrolyte functions to conduct ions between the positive electrode and the negative electrode.

[0225] In some embodiments, the electrolyte employs an electrolyte solution that includes an electrolyte salt and an organic solvent.

[0226] Taking a lithium battery cell as an example, the electrolyte salt can include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium bisoxalato borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP).

[0227] Taking a sodium battery cell as an example, the electrolyte salt can include, but is not limited to, one or more of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bisfluorosulfonylimide (NaFSI), sodium bis-trifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalato borate (NaDFOB), sodium bisoxalato borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalato phosphate (NaDFOP), and sodium tetrafluorooxalato phosphate (NaTFOP).

[0228] In some embodiments, the organic solvent can include, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, crown ether.

[0229] In some embodiments, the electrolyte can further include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and / or an additive capable of improving certain properties of the secondary battery cell, such as an additive capable of improving overcharge performance, an additive capable of improving high-temperature performance, an additive capable of improving low-temperature performance, and / or the like.

[0230] Optionally, the additive can include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), and / or vinyl sulfate (DTD).

[0231] Methods for preparing secondary battery cells are known. In some embodiments, a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte can be assembled to form a secondary battery cell. As an example, a positive electrode sheet, a separator, and a negative electrode sheet can be formed into an electrode assembly via a winding process and / or a stacking process, the electrode assembly can be placed in an outer package, the electrolyte described above can be injected after drying, and the secondary battery cell can be obtained after processes such as vacuum packaging, standing, and formation.

[0232] Embodiments

[0233] The following examples further illustrate the present disclosure, which is not limited to the examples, as various modifications and equivalents will be apparent to one skilled in the art. Unless otherwise stated, all proportions, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used as received without further purification, and the instruments used in the examples are commercially available.

[0234] Example 1

[0235] Preparation of the separator

[0236] A pre-emulsion was prepared by emulsifying 0.3 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 52.5 g of γ-methacryloxypropyl triisopropoxysilane, 3 g of 3-methacryloxypropyl triethoxysilane, and 4.5 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 84°C for 1.5 h of curing reaction. The product of the emulsion polymerization reaction was dried in a vacuum drying oven at 105°C for 8 h to obtain a block solid. The block solid was naturally cooled in air, broken by an air flow crusher, and wet ground with water to obtain a dispersion of silicon-containing organic resin 1#. The grinding speed was 800 rpm for 1 h. The grinding medium was zirconia balls with a diameter of 0.6-0.8 mm.

[0237] The dispersion liquid, the adhesive polymethyl methacrylate and the dispersant sodium carboxymethyl cellulose were stirred uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the silicon-containing organic resin, the dispersant sodium carboxymethyl cellulose and the adhesive polymethyl methacrylate in the heat-resistant layer slurry was 90:2:8.

[0238] The commercially available polyvinylidene fluoride particles, the adhesive polymethyl methacrylate, the dispersant sodium carboxymethyl cellulose and the ether-based surfactant were stirred uniformly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0239] A commercially available polyethylene microporous film with a thickness of 7 μm was used as the porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure coating, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer. After drying and slitting processes, the separator film was obtained.

[0240] Preparation of secondary battery monomer

[0241] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, the positive electrode binder polyvinylidene fluoride (PVDF) and the positive electrode conductive agent carbon black were added into N-methyl pyrrolidone (NMP) at a mass ratio of 97:2:1, and after being fully stirred and mixed uniformly, a positive electrode slurry was prepared. The positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil, and then after drying, cold pressing and slitting, a positive electrode sheet was obtained.

[0242] The negative electrode active material artificial graphite, the negative electrode conductive agent acetylene black, the negative electrode binder styrene butadiene rubber (SBR) and the thickening agent sodium carboxymethyl cellulose were added into deionized water at a mass ratio of 96.0:1.5:1.5:1, and after being fully stirred and mixed uniformly, a negative electrode slurry was prepared. The negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and then after drying, cold pressing and slitting, a negative electrode sheet was obtained.

[0243] At 25°C, ethylene carbonate (EC) and methyl ethyl carbonate (EMC) were mixed at a volume ratio of 3:7 to obtain a mixed solvent, and then LiPF6, vinylene carbonate (VC) and vinyl sulfate (DTD) were dissolved in the mixed solvent to obtain an electrolyte. The concentration of LiPF6 was 1 mol / L. The mass fraction of VC was 2%, and the mass fraction of DTD was 3%, based on the mass of the electrolyte.

[0244] The positive electrode sheet, the separator film and the negative electrode sheet were stacked in order and wound and hot-pressed to obtain an electrode assembly, and then the electrode assembly was loaded into a hard-shell outer package. After injection of the electrolyte, standing and formation, a secondary battery monomer was obtained.

[0245] Example 2

[0246] The preparation of the secondary battery cell was the same as that of Example 1 except for the following differences.

[0247] Preparation of the separator

[0248] A pre-emulsion was prepared by emulsifying 0.3 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 52.5 g of γ-methacryloxypropyl triisopropoxysilane, 3 g of 3-methacryloxypropyl triethoxysilane, and 4.5 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 84°C for 1.5 h of curing reaction. The product of the emulsion polymerization reaction was dried in a vacuum drying oven at 105°C for 8 h to obtain a block solid. The block solid was naturally cooled in air, broken by an air flow crusher, and wet ground with water to obtain a dispersion of silicon-containing organic resin 2#. The grinding speed was 800 rpm for 2 h. The grinding medium was zirconium oxide balls with a diameter of 0.6-0.8 mm.

[0249] The dispersion, the binder polymethyl methacrylate, and the dispersant sodium carboxymethyl cellulose were uniformly stirred in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the silicon-containing organic resin, the dispersant sodium carboxymethyl cellulose, and the binder polymethyl methacrylate in the heat-resistant layer slurry was 90:2:8.

[0250] Commercial polyvinylidene fluoride particles, a binder polymethyl methacrylate, a dispersant sodium carboxymethyl cellulose, and an ether-based surfactant were uniformly stirred in deionized water at a solid mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0251] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure coating, and the adhesive layer slurry was sprayed on the heat-resistant layer after drying. Then, the separator was obtained by drying and slitting.

[0252] Example 3

[0253] The preparation of the secondary battery cell was the same as that of Example 1 except for the following differences.

[0254] Preparation of the separator

[0255] A pre-emulsion was prepared by emulsifying 0.3 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 52.5 g of γ-methacryloxypropyl triisopropoxysilane, 3 g of 3-methacryloxypropyl triethoxysilane, and 4.5 g of divinylbenzene. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 84°C for 1.5 h of curing reaction. The product of the emulsion polymerization reaction was dried in a vacuum drying oven at 105°C for 8 h to obtain a block solid. The block solid was naturally cooled in air, broken by an air flow crusher, mixed with water, and wet ground to obtain a silicon-containing organic resin 3# dispersion. The grinding speed was 800 rpm, and the time was 3 h. The grinding medium was zirconium oxide balls with a diameter of 0.6-0.8 mm.

[0256] The above dispersion, the binder polymethyl methacrylate, and the dispersant sodium carboxymethyl cellulose were uniformly stirred in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the silicon-containing organic resin, the dispersant sodium carboxymethyl cellulose, and the binder polymethyl methacrylate in the heat-resistant layer slurry was 90:2:8.

[0257] Commercial polyvinylidene fluoride particles, a binder polymethyl methacrylate, a dispersant sodium carboxymethyl cellulose, and an ether-based surfactant were uniformly stirred in deionized water at a solid content mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0258] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by micro-gravure, and the adhesive layer slurry was sprayed on the heat-resistant layer after drying. Then, the isolation film was obtained by drying and slitting.

[0259] Comparative Example 1

[0260] The secondary battery monomer was prepared in the same manner as in Example 1, except for the following differences.

[0261] Preparation of the isolation film

[0262] A pre-emulsion was prepared by emulsifying 0.3 g of sodium persulfate, 0.3 g of sodium bicarbonate, 1.5 g of sodium dodecyl sulfate, 30 g of deionized water, 60 g of γ-methacryloxypropyl triisopropoxysilane. A reactor was taken, 210 g of deionized water was added, and the temperature was raised to 70°C. The pre-emulsion was added dropwise under nitrogen protection and stirring. After 4 h of reaction, the temperature was raised to 84°C for 1.5 h of curing reaction to obtain a silicon-containing organic resin D1# emulsion.

[0263] The above emulsion, adhesive polymethyl methacrylate and dispersant sodium carboxymethyl cellulose were stirred uniformly in deionized water to obtain a heat-resistant layer slurry. The solid mass ratio of the silicon-containing organic resin, the dispersant sodium carboxymethyl cellulose and the adhesive polymethyl methacrylate in the heat-resistant layer slurry was 90:2:8.

[0264] The commercially available polyvinylidene fluoride particles, adhesive polymethyl methacrylate, dispersant sodium carboxymethyl cellulose and ether-based surfactant were stirred uniformly in deionized water at a solid content mass ratio of 87:8:3:2 to obtain an adhesive layer slurry.

[0265] A commercially available polyethylene microporous film with a thickness of 7 μm was used as a porous base film. The heat-resistant layer slurry was coated on both surfaces of the porous base film by microgravure method, and after drying, the adhesive layer slurry was sprayed on the heat-resistant layer, and then dried and cut to obtain the separator film.

[0266] The silicon-containing organic resins 1# to 3# prepared above satisfy the following characteristics: the silicon-containing organic resin is a network structure formed with a carbon-carbon bond as the main chain, the side chain contains a siloxane structure and a benzene ring structure, it has no melting point, and has no glass transition temperature T g .

[0267] Performance test

[0268] (1) Heat shrinkage rate test of the separator film

[0269] The heat shrinkage rate test of the separator film can refer to GB / T 36363-2018.

[0270] The separator film was punched into a sample with a width of 50 mm and a length of 100 mm by a punch press, and 5 parallel samples were placed on an A4 paper, and then the A4 paper with the samples was placed on a corrugated paper with a thickness of 1 mm to 5 mm.

[0271] The temperature of the air blowing oven was set to 130℃, and after the temperature reached the set temperature and stabilized for 60 min, the A4 paper placed on the corrugated paper was put into the air blowing oven, and the timing started. After reaching the set time (1 h in the present disclosure), the length and width of the separator film were measured, and the values were marked as a and b, respectively.

[0272] Heat shrinkage rate calculation: longitudinal (MD) heat shrinkage rate = [(100-a) / 100] x 100%, transverse (TD) heat shrinkage rate = [(50-b) / 50] x 100%, and the average value of 3 parallel samples was taken as the test result.

[0273] (2) Electrolyte wettability test of the separator film

[0274] Cut the separator into 3 pieces of 5mm x 100mm, drop 1mL electrolyte in the middle of the piece, and let it stand for 2min. If the electrolyte does not spread further, record the distance of electrolyte spreading as the electrolyte wetting length of the separator. The greater the value, the better the electrolyte wetting property of the separator. Take the average value of 3 parallel samples as the test result.

[0275] (3) Cycle performance test of the secondary battery cell

[0276] At 25℃, the secondary battery cell is charged at 1 / 3C constant current to 4.25V, then charged at 4.25V constant voltage to a current of 0.05C, and left for 5min, then discharged at 1 / 3C constant current to 2.8V. The obtained discharge capacity is recorded as the initial capacity C0. Repeat the above charging and discharging steps and record the discharge capacity Cn of the secondary battery cell after the nth cycle. The capacity retention rate Pn of the secondary battery cell after each cycle is (Cn / C0) x 100%. The cycle performance of the secondary battery cell can be reflected by the capacity retention rate after 500 cycles.

[0277] Table 1

[0278] From the above test results, it can be seen that the silicon-containing organic resin of the present disclosure can improve the heat resistance of the separator, the electrolyte wetting property of the separator, and the cycle performance of the secondary battery cell.

[0279] The particle size of the primary particles in the silicon-containing organic resin prepared in the above Examples 1 to 3 is in the range of 30nm to 250nm.

[0280] Figure 3 shows a scanning electron microscope image of the silicon-containing organic resin prepared in Example 1.

[0281] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having substantially the same technical idea and playing the same role and effect within the scope of the technical solutions of the present disclosure are all included in the technical scope of the present disclosure. In addition, within the scope of the main idea of the present disclosure, various modifications that can be thought of by those skilled in the art, and other ways constructed by combining part of the elements in the embodiments are also included in the scope of the present disclosure.

Claims

1. An isolation membrane comprising a porous base membrane and a porous coating on at least one side of the porous base membrane, wherein, The porous coating comprises a silicon-containing organic resin, and the silicon-containing organic resin comprises agglomerate particles of primary particles.

2. The separator film according to claim 1, wherein The primary particles have a particle size of 30 nm to 250 nm.

3. The separator film according to claim 1 or 2, wherein The silicon-containing organic resin has a volume distribution particle size Dv50 of 300 nm to 800 nm.

4. The separator film according to any one of claims 1 to 3, wherein The silicon-containing organic resin has no melting point; and / or The silicon-containing organic resin has no glass transition temperature below 300℃.

5. The separator film according to any one of claims 1 to 4, wherein The silicon-containing organic resin has 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℃ for 7 days; and / or The silicon-containing organic resin has 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℃ for 7 days; and / or The silicon-containing organic resin has no oxidation peak in the cyclic voltammetry curve of the first cycle in the voltage range of 2.50V to 4.40V.

6. The separator film according to any one of claims 1 to 5, wherein The true density of the silicon-containing organic resin is 1.1 g / cm 3 -1.4 g / cm 3 .

7. The separator film according to any one of claims 1 to 6, wherein The silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic resin contains carbon-carbon bonds and siloxane structures.

8. The separator film according to any one of claims 1 to 7, wherein The silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as the main chain, and the side chains contain siloxane structures and benzene ring structures.

9. The separator film according to any one of claims 1 to 8, wherein The silicon-containing organic resin is a silicon-containing organic crosslinking resin, and the silicon-containing organic crosslinking resin comprises crosslinking structure units, Optionally, the crosslinking structure units comprise one or more of divinylbenzene structure units, diethylene glycol divinyl ether structure units, triethylene glycol divinyl ether structure units, diallyl maleate structure units, ethylene glycol dimethacrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethylhexanedioyl bis[2-ethylaziridine] structure units, 1,1-nonanedioyl bis[2-methylaziridine] structure units, 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tris(3-aziridinyl) propionate structure units.

10. The separator film according to any one of claims 1 to 9, wherein The mass content of the silicon-containing organic resin in the porous coating is 50% to 99% based on the total mass of the porous coating; and / or The thickness of the porous coating is 0.5μm to 5μm.

11. The separator film according to any one of claims 1 to 10, wherein The separator film has a longitudinal heat shrinkage rate of less than or equal to 1.5% when heated at 130℃ for 1h; and / or, The isolation film has a transverse heat shrinkage rate of less than or equal to 1.5% at 130℃ for 1h.

12. A silicon-containing organic resin, wherein, The silicon-containing organic resin comprises agglomerate particles of primary particles.

13. The silicon-containing organic resin of claim 12, wherein, The primary particles have a particle size of 30nm-250nm.

14. The silicon-containing organic resin of claim 12 or 13, wherein, The silicon-containing organic resin has a volume distribution particle size Dv50 of 300nm-800nm.

15. The silicon-containing organic resin according to any one of claims 12-14, wherein, The silicon-containing organic resin has no melting point; and / or, The silicon-containing organic resin has no glass transition temperature below 300℃.

16. The silicon-containing organic resin according to any one of claims 12-15, wherein, The silicon-containing organic resin has 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℃ for 7 days; and / or, The silicon-containing organic resin has 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℃ for 7 days; and / or, The silicon-containing organic resin has no oxidation peak in a cyclic voltammetry curve of the first cycle in a voltage range of 2.50V to 4.40V.

17. The silicon-containing organic resin of any one of claims 12-16, wherein, The true density of the silicon-containing organic resin is 1.1 g / cm 3 -1.4 g / cm 3 .

18. The silicon-containing organic resin of any of claims 12-17, wherein, The silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic resin contains carbon-carbon bonds and siloxane structures.

19. The silicon-containing organic resin of any of claims 12-18, wherein, The silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic resin is a network structure formed with carbon-carbon bonds as a main chain, and side chains containing siloxane structures and benzene ring structures.

20. The silicon-containing organic resin of any of claims 12-19, wherein, The silicon-containing organic resin is a silicon-containing organic crosslinked resin, and the silicon-containing organic crosslinked resin comprises crosslinking structure units, Optionally, the crosslinking structure units comprise one or more of divinylbenzene structure units, diethylene glycol divinyl ether structure units, triethylene glycol divinyl ether structure units, diallyl maleate structure units, ethylene glycol dimethacrylate structure units, 1,4-butanediol diacrylate structure units, 1,6-hexanediol diacrylate structure units, 1,8-octanediol diacrylate structure units, trimethylolpropane triacrylate structure units, pentaerythritol trimethacrylate structure units, tetraethylene glycol dimethacrylate structure units, tripropylene glycol diacrylate structure units, 2,2,4-trimethylhexanedioyl bis[2-ethylaziridine] structure units, 1,1-nonanedioyl bis[2-methylaziridine] structure units, 1,1-(1,3-phenylenedicarbonyl) bis[2-methylaziridine] structure units, trimethylolpropane tris(2-methyl-1-aziridinyl propionate) structure units, trimethylolpropane-tris[3-(2-methylaziridinyl) propionate] structure units, pentaerythritol tris(3-aziridinyl) propionate structure units.

21. A method for preparing a silicon-containing organic resin, comprising the steps of: providing a pre-emulsion comprising monomers, a crosslinking agent, an emulsifier, an initiator, and water, wherein the monomers comprise a silane coupling agent; performing an emulsion polymerization reaction under conditions of heating, inert gas protection, and stirring; and drying the product of the emulsion polymerization reaction, and then performing a crushing process and a grinding process to obtain the silicon-containing organic resin.

22. The method of claim 21, wherein, the temperature for drying the product obtained from the emulsion polymerization reaction is 80-150°C; and / or, the time for drying the product obtained from the emulsion polymerization reaction is 2-12h.

23. The method of claim 21 or 22, wherein, the grinding process comprises the following steps: mixing the material after the crushing process with a solvent, a grinding medium and optionally a dispersant to obtain a mixed slurry, and then subjecting the mixed slurry to grinding treatment to obtain the silicon-containing organic resin.

24. The method of claim 23, wherein, The grinding process satisfies at least one of the following conditions (1) to (6): (1) the solvent comprises one or more of water, methanol, ethanol; (2) the dispersant comprises one or more of polyacrylic acid type dispersant, carboxymethyl cellulose type dispersant, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone; (3) the grinding medium comprises one or more of zirconia balls, alumina balls, silicon nitride balls; (4) the average particle size of the grinding medium is 0.1-2mm; (5) the filling rate of the grinding medium is 30-80%; (6) the rotation speed of the grinding is 500-3000rpm.

25. The method of any one of claims 21-24, wherein, the heating temperature of the maturation stage of the emulsion polymerization reaction is 70-95°C; and / or, the heating time of the maturation stage of the emulsion polymerization reaction is 1-5h; and / or, the inert gas comprises one or more of nitrogen, argon, helium.

26. The method of any one of claims 21-25, wherein, The emulsion polymerization reaction comprises the following steps: under the conditions of a first temperature, inert gas protection and stirring, the pre-emulsion is added dropwise into a reactor containing water, and after a first time, the temperature is raised to the heating temperature of the maturation stage for maturation reaction to obtain the silicon-containing organic resin.

27. The method of claim 26, wherein, the first temperature is 55-70°C; and / or, the first time is 3-6h.

28. The method of any one of claims 21-27, wherein, The silane coupling agent includes one or more of a vinyl group and / or an acryloxy group, and / or optionally includes one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyltri(methoxyethoxy)silane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, tri-t-butoxyvinylsilane, vinyltris(β-methoxyethoxy)silane, ethylene tris[(1-methylethenyl)oxy]silane, vinyltris-t-butylperoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, diethylmethylvinylsilane, vinyl dimethyl ethoxysilane, methylvinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, methylvinyldimethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane. The crosslinking agent includes one or more of divinylbenzene, diethylene glycol divinyl ether, triethylene glycol divinyl ether, diallyl maleate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate, tetraethylene glycol dimethacrylate, tripropyleneglycol diacrylate, 2,2,4-trimethylhexanedioic acid bis[2-ethylaziridine], 1,1-nonanedioic acid bis[2-methylaziridine], 1,1-(1,3-phenylenedicarbonyl)bis[2-methylaziridine], trimethylolpropane tris(2-methyl-1-aziridinylpropionate), trimethylolpropane-tris[3-(2-methylaziridinyl)propionate], pentaerythritol tris(3-aziridinyl)propionate; and / or The mass fraction of the crosslinking agent is 1.5% to 18% based on the total mass of the monomer and the crosslinking agent being 100%.

29. A dispersion of a silicon-containing organic resin comprising the silicon-containing organic resin of any one of claims 12 to 20 and a dispersant, or obtained by the method of any one of claims 21 to 28.

30. A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator of any one of claims 1 to 11, the separator being disposed between the positive electrode sheet and the negative electrode sheet.

31. A battery device comprising a plurality of the secondary battery cell of claim 30.

32. An electric device comprising the secondary battery cell of claim 30 or the battery device of claim 31.

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