Non-fluoropolymer, non-fluoropolymer composite separator and applications

Abstract

The application provides a non-fluoropolymer, a non-fluoropolymer composite diaphragm and application, the non-fluoropolymer includes polymer A and the polymer B at least partially coated on the surface of polymer A, the crosslinking degree of polymer A is X1, the crosslinking degree of polymer B is X2, 5%≤X1≤10%, 50%≤X2≤60%;The non-fluoropolymer composite diaphragm includes base film and coating layer coated on at least one side of base film.The non-fluoropolymer particles of the application have a higher swelling rate at high temperature, also have the reversible characteristics of absorbing and releasing electrolyte, the non-fluoropolymer and the non-fluoropolymer composite diaphragm are applied in the battery, when the battery abnormally heats, the non-fluoropolymer swells rapidly, blocks the ion shuttle channel, avoids the further deterioration of temperature, improves the safety performance of the battery, and when the temperature returns to normal, the non-fluoropolymer particles can restore to the original morphology, restore the ion shuttle channel, so as to not affect the subsequent cycle performance of the battery.

Description

A non-fluoropolymer, a non-fluoropolymer composite membrane and its applications Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a non-fluoropolymer, a non-fluoropolymer composite separator, and their applications. Background Technology

[0002] The separator, positioned between the positive and negative electrodes within the battery cell, acts as an insulator to prevent short circuits caused by contact between the electrodes. Because the bare base film has no adhesive bond to the electrodes, the battery cell is prone to softening when used at the battery terminal. To improve the cell's rigidity, current technology involves coating the bare base film with a polymer coating, such as PVDF or PMMA, to enhance the overall rigidity of the cell.

[0003] With the EU's ban on fluorine, PMMA has received increasing attention. However, since PMMA is an amorphous polymer, it is easily flattened when used in batteries, which can cause the coating separator to become clogged, increasing internal resistance and affecting cell performance. Patent CN118530416A discloses a polymer microsphere, a coated separator suitable for cold pressing bonding, and a preparation method thereof. Specifically, it discloses a core-shell structure polymer with a core structure possessing low crosslinking degree, low glass transition temperature, and low structural strength, while its shell structure possesses high crosslinking degree, high glass transition temperature, and low volumetric elongation. Applying this to the adhesive layer of a coated separator allows the hot pressing process in battery cell manufacturing to be replaced with cold pressing, effectively reducing energy consumption in battery cell production. Patent CN118399005A discloses a separator, a secondary battery, and an electrical device. Specifically, it discloses a phosphate ester-modified core-shell polymer particle with a core Tg higher than the shell Tg. Applying this to a lithium battery coated separator can significantly reduce the separator's swelling rate, improve its adhesion, electrolyte wettability, heat resistance, flame retardancy, and conductivity, thereby improving the battery cell's cycle performance, charge-discharge performance, and excellent safety performance.

[0004] In existing technologies, polymer particles are applied to coated membranes, which are then combined with electrode sheets to form a battery cell. During the electrolyte injection and hot-pressing process, some polymer structures collapse directly. For example, the core-shell structure polymer in patent CN118530416A severely clogs the pores of the coated membrane and also affects the electrolyte storage space of the coating and electrode sheets, thus impacting cycle performance. Some polymers, while maintaining structural stability, expand in volume after absorbing electrolyte. After hot-pressing and cooling to room temperature, the polymer cannot return to its original morphology, which also easily leads to pore blockage and affects the cycle performance of the battery cell. For example, in patent CN118399005A, under uncontrolled battery cell temperature, the polymer can rapidly swell and block the pores of the coated membrane, increasing the internal resistance of the battery cell and slowing down the further rise in battery cell temperature. However, after the battery cell temperature returns to room temperature, due to the irreversible nature of the swelling, the rapidly swollen polymer severely clogs the pores of the coated membrane, resulting in a severe deterioration in the cycle performance of the battery cell.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to address the safety issues of battery cells during abnormal temperature rise and the reversibility of cycling after cooling in existing technologies. It provides a non-fluoropolymer / non-fluoropolymer composite separator and its application. The non-fluoropolymer particles exhibit a high swelling ratio at high temperatures and possess reversible electrolyte absorption and release characteristics. When the non-fluoropolymer / non-fluoropolymer composite separator is applied to the battery cell, the non-fluoropolymer swells rapidly during abnormal temperature rise, blocking ion shuttle channels and preventing further temperature deterioration, thus improving the safety performance of the battery cell. Simultaneously, when the temperature returns to normal, the non-fluoropolymer particles can recover their original morphology, restoring the ion shuttle channels and thus not affecting the subsequent cycling performance of the battery cell.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] A non-fluoropolymer includes polymer A and polymer B at least partially coated on the surface of polymer A, wherein the degree of crosslinking of polymer A is X1 and the degree of crosslinking of polymer B is X2, 5%≤X1≤10% and 50%≤X2≤60%.

[0009] Furthermore, the non-fluoropolymer includes a core layer and a shell layer at least partially covering the surface of the core layer, the core layer comprising polymer A and the shell layer comprising polymer B.

[0010] Furthermore, the glass transition temperature of polymer A is Tg1, and the glass transition temperature of polymer B is Tg2, where 100℃≤Tg1≤110℃ and -10℃≤Tg2≤10℃.

[0011] Furthermore, the elastic modulus of the shell is E, where 5MPa≤E≤15MPa.

[0012] Furthermore, the particle size of the non-fluoropolymer is 0.4 μm to 4.0 μm.

[0013] Furthermore, the ratio of the total thickness of the shell to the particle size of the non-fluoropolymer is N, where 10% ≤ N ≤ 20%.

[0014] Furthermore, the swelling rate of the core layer is 20%~50% at a low temperature of 60°C and 450%~550% at a high temperature of 120°C.

[0015] Furthermore, the non-fluoropolymer has a comprehensive swelling rate of 30%~80% at a low temperature of 60°C and a comprehensive swelling rate of 500%~600% at a high temperature of 120°C.

[0016] Furthermore, the high-temperature volume recovery coefficient η of the non-fluoropolymer is 1≤η≤1.5.

[0017] Furthermore, the mass of polymer A accounts for 50% to 75% of the mass of the non-fluoropolymer.

[0018] Furthermore, the mass of polymer B accounts for 25% to 50% of the mass of the non-fluoropolymer.

[0019] Furthermore, the polymer A is polymerized from polymeric monomer A1 and crosslinking monomer A2; the crosslinking monomer A2 accounts for 1% to 5% of the mass of the polymer A.

[0020] Furthermore, the polymer B is polymerized from polymeric monomer B1 and crosslinking monomer B2; the crosslinking monomer B2 accounts for 10% to 15% of the mass of the polymer B.

[0021] Further, the polymeric monomer A1 includes at least two of methyl methacrylate, butyl methacrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methacrylonitrile, styrene, acrylonitrile, and methacrylonitrile.

[0022] Further, the crosslinking monomer A2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0023] Further, the polymeric monomer B1 includes at least two of the following: ethyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl acrylate, n-butyl acrylate, butyl methacrylate, methyl methacrylate, methacrylonitrile, styrene, and acrylonitrile.

[0024] Further, the crosslinking monomer B2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0025] A non-fluoropolymer composite membrane comprises a base membrane and a coating layer coated on at least one side of the base membrane, wherein the coating layer comprises the aforementioned non-fluoropolymer, and the coverage of the non-fluoropolymer particles is 10% to 30%.

[0026] Furthermore, the density of the coating layer is 0.1 g / m². 2 ~0.5g / m 2 .

[0027] Furthermore, the coating thickness is 0.4 μm to 4.0 μm.

[0028] Furthermore, the thickness of the base film is 4μm~16μm.

[0029] Furthermore, the base film is one of PE base film, PP base film, or PP and PE composite base film.

[0030] Furthermore, the coating layer also includes an adhesive, which accounts for 1% to 6% of the mass of the non-fluoropolymer; the adhesive includes at least one of styrene-butadiene rubber, polyacrylic acid, polyacrylamide, polyacrylonitrile, epoxy resin, and polyacrylate.

[0031] Furthermore, the coating layer also includes a wetting agent, which accounts for 0.1% to 1.0% of the mass of the non-fluoropolymer; the wetting agent includes at least one of alkyl sulfate, sulfonate, polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and fatty acid polyoxyethylene ether.

[0032] The above-mentioned non-fluoropolymers and the above-mentioned non-fluoropolymer composite membranes are used in the preparation of battery cells, secondary batteries, and electrical appliances.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. The non-fluoropolymer particles of the present invention have good structural stability at high temperature, low swelling rate at low temperature, and high swelling rate at high temperature. At the same time, after high-temperature swelling and cooling, the non-fluoropolymer can restore its original morphology, maintain structural stability, and realize the reversibility of polymer swelling by absorbing electrolyte and releasing electrolyte.

[0035] 2. The non-fluoropolymer particles of this invention have a core-shell structure, with the Tg1 of the core layer being higher than that of the shell layer, maintaining the structural integrity of the non-fluoropolymer particles. The high-temperature swelling rate of the core layer is much higher than that at low temperatures, which can protect the battery cell under abnormal temperature rise and improve the safety performance of the battery cell. To ensure the reversibility of electrolyte absorption and release of the non-fluoropolymer particles, the crosslinking agent ratio of the shell layer of the non-fluoropolymer is higher than that of the core layer, thereby increasing the crosslinking degree of the shell layer and giving the shell layer a higher elastic modulus. When the non-fluoropolymer swells at high temperatures, the core layer is not easily swelled and broken, thus achieving the stability of the non-fluoropolymer during high-temperature swelling.

[0036] 3. The non-fluoropolymer particle core-shell structure of this invention achieves temperature response and triggering through the glass transition temperature difference between its core and shell layers: at low temperatures, the high Tg of the core layer provides rigid support and has a low swelling rate in the electrolyte; at high temperatures, the movement of the core layer chain segments is activated, achieving rapid swelling in the electrolyte. During this process, the polymer effectively blocks the pores of the coated membrane, reducing lithium-ion migration channels, thereby inhibiting the chain exothermic reaction inside the cell and significantly improving the safety performance of the cell. At the same time, through the difference in crosslinking degree between its core and shell layers, the swelling behavior is constrained and reversible: the low crosslinking degree of the core layer allows it to swell fully, while the low Tg of the shell layer, combined with its high crosslinking degree and high modulus, effectively constrains the swelling of the core layer and prevents the shell layer from cracking. Furthermore, it provides elastic recovery force after the temperature decreases, allowing the particle morphology to recover and the membrane ion channels to reopen, ensuring the reversibility of the cell cycle and the long-term reliability after abnormal heating and cooling.

[0037] 4. The present invention relates to a non-fluoropolymer composite separator and its application, wherein non-fluoropolymer particles are coated on a base film and then assembled with positive and negative electrodes to form a battery. Under abnormal temperature rise conditions inside the battery, the non-fluoropolymer can rapidly swell and block the ion shuttle channels, preventing further deterioration of the cell temperature and improving the safety performance of the cell. At the same time, when the cell temperature returns to normal temperature, the non-fluoropolymer particles can restore their original morphology, release the ion shuttle channels, and not affect the cycle performance of the cell, thus achieving safety under abnormal temperature rise and cycle reversibility after cooling. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 is a schematic diagram of the non-fluoropolymer structure of the present invention;

[0040] Figure 2 is an electron microscope image of a discontinuous coating (under a microscopic electron microscope) of a single non-fluoropolymer particle or multiple non-fluoropolymer particles connected and distributed on a base film according to the present invention. Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0042] A non-fluoropolymer includes polymer A and polymer B at least partially coated on the surface of polymer A. The degree of crosslinking of polymer A is X1, and the degree of crosslinking of polymer B is X2. X1 is 5% ≤ X1 ≤ 10%, and X1 includes, but is not limited to, point values ​​or ranges between point values ​​of 5%, 6%, 7%, 8%, 9%, and 10%. X2 is 50% ≤ X2 ≤ 60%, and X2 includes, but is not limited to, point values ​​or ranges between point values ​​of 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, and 60%.

[0043] Preferably, the non-fluoropolymer includes a core layer and a shell layer that at least partially covers the surface of the core layer, as shown in FIG1. ​​More preferably, the non-fluoropolymer includes a core layer and a shell layer that completely covers the surface of the core layer.

[0044] In this invention, the crosslinking degree of the non-fluoropolymer shell is much greater than that of the core layer. The shell has a higher elastic modulus, which prevents the non-fluoropolymer from bursting out and overflowing when the core layer absorbs electrolyte and swells at high temperatures, thus avoiding the collapse of the non-fluoropolymer structure. When the temperature returns to room temperature, the non-fluoropolymer releases the electrolyte and can restore its original morphology without affecting the ion shuttle channels after abnormal heating and cooling of the battery cell. This achieves the safety of abnormal heating of the battery cell and the reversibility of cycling after cooling.

[0045] Preferably, the core layer comprises polymer A, the shell layer comprises polymer B, the glass transition temperature of polymer A is Tg1, and the glass transition temperature of polymer B is Tg2, 100℃≤Tg1≤110℃, Tg1 includes, but is not limited to, a point value or a range between points of 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, and 110℃, -10℃≤Tg2≤10℃, and Tg2 includes, but is not limited to, a point value or a range between points of -10℃, -9℃, -8℃, -7℃, -6℃, -5℃, -4℃, -3℃, -2℃, -1℃, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃, and 10℃, preferably 0℃≤Tg2≤10℃.

[0046] In this invention, the core layer Tg1 is greater than the shell layer Tg2, ensuring that the non-fluoropolymer has a strong rigid structure. After the non-fluoropolymer is applied to the coated separator and hot-pressed with the electrode sheet, its morphology will not collapse, providing storage space for the electrolyte. Secondly, in terms of the swelling of the non-fluoropolymer in the electrolyte, the swelling of the core layer is small at low temperatures and increases dramatically at high temperatures. After the non-fluoropolymer is applied to the coated separator and electrode sheet to prepare the battery cell, when the battery cell temperature rises abnormally, the non-fluoropolymer quickly swells and blocks the ion shuttle channel, preventing the battery cell temperature from rising further and improving the safety of the battery cell.

[0047] In this invention, the Tg1 of the core layer of the non-fluoropolymer core-shell structure is higher than that of the shell layer, which maintains the structural integrity of the non-fluoropolymer particles. The high-temperature swelling rate of the core layer is much higher than that at low temperatures, which can protect the battery cell under abnormal temperature rise and improve the safety performance of the battery cell. It also ensures the reversibility of the non-fluoropolymer particles absorbing and releasing electrolyte.

[0048] Preferably, the elastic modulus of the shell is E, 5MPa≤E≤15MPa, where E includes, but is not limited to, point values ​​or ranges between point values ​​of 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, and 15MPa.

[0049] The shell of this invention has a high elastic modulus. When the non-fluoropolymer swells at high temperature, the core layer is not easily swelled and broken, thus achieving the stability of the non-fluoropolymer during high-temperature swelling. It can restrain the stress generated by the high-temperature swelling of the core polymer and prevent the shell from being squeezed and collapsing. When the temperature returns to room temperature, the amount of electrolyte released by the core polymer decreases, and the shell polymer can return to its original morphology. This gives the non-fluoropolymer a small high-temperature volume recovery coefficient, which has no impact on the subsequent cell cycle performance.

[0050] The non-fluoropolymer core-shell structure of this invention achieves temperature response and triggering through the glass transition temperature difference between its core and shell layers: at low temperatures, the high Tg of the core layer provides rigid support and has a low swelling rate in the electrolyte; at high temperatures, the movement of the core layer chain segments is activated, achieving rapid swelling in the electrolyte. During this process, the polymer effectively blocks the pores of the coated membrane, reducing lithium-ion migration channels, thereby inhibiting the chain exothermic reaction inside the cell and significantly improving the safety performance of the cell. At the same time, the difference in crosslinking degree between its core and shell layers achieves constraint and reversibility of the swelling behavior: the low crosslinking degree of the core layer allows it to swell fully, while the low Tg of the shell layer, combined with its high crosslinking degree and high modulus, effectively constrains the swelling of the core layer and prevents the shell layer from cracking. Furthermore, it provides elastic recovery force after the temperature decreases, allowing the particle morphology to recover and the membrane ion channels to reopen, ensuring the reversibility of the cycle and the long-term reliability of the cell after abnormal heating and cooling.

[0051] Preferably, the particle size of the non-fluoropolymer is 0.4μm to 4.0μm, including but not limited to 0.4μm, 0.8μm, 1.2μm, 1.6μm, 2μm, 2.4μm, 2.8μm, 3.2μm, 3.6μm, and 4μm.

[0052] Preferably, the ratio of the total thickness of the shell (here, the total thickness of the shell is twice the thickness of the shell itself) to the particle size of the non-fluoropolymer is N, where 10% ≤ N ≤ 20%, and N includes, but is not limited to, point values ​​or ranges between 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%. By setting the thickness of the non-fluoropolymer shell within a suitable range, the integrity of the non-fluoropolymer and its high-temperature swelling properties can be guaranteed.

[0053] Preferably, the swelling rate of the core layer at a low temperature of 60°C is 20%~50%, including but not limited to 20%, 25%, 30%, 35%, 40%, 45%, and 50%, and the swelling rate at a high temperature of 120°C is 450%~550%, including but not limited to 450%, 460%, 470%, 480%, 490%, 500%, 510%, 520%, 530%, 540%, and 550%. Controlling the appropriate and controllable swelling capacity of the core layer polymer is to ensure the performance of the battery cell after formation.

[0054] Preferably, the comprehensive swelling rate of the non-fluoropolymer at a low temperature of 60°C is 30%~80%, including but not limited to 30%, 40%, 50%, 60%, 70%, and 80%, and the comprehensive swelling rate at a high temperature of 120°C is 500%~600%, including but not limited to 500%, 510%, 520%, 530%, 540%, 550%, 560%, 570%, 580%, 590%, and 600%.

[0055] Preferably, the high-temperature volume recovery coefficient η of the non-fluoropolymer is 1≤η≤1.5, and η includes, but is not limited to, point values ​​of 1, 1.1, 1.2, 1.3, 1.4, and 1.5 or the range between point values.

[0056] Preferably, the mass of polymer A accounts for 50% to 75% of the mass of the non-fluoropolymer, including but not limited to 50%, 55%, 60%, 65%, 70%, and 75%.

[0057] Preferably, polymer A is polymerized from polymeric monomer A1, crosslinking monomer A2, and a small amount of additives. The additives include at least one emulsifier and an initiator.

[0058] Preferably, the emulsifier accounts for 0.5% to 2.5% of the mass of polymer A, including but not limited to 0.5%, 1%, 1.5%, 2%, and 2.5%.

[0059] Preferably, the initiator accounts for 0.5% to 2.5% of the mass of polymer A, including but not limited to 0.5%, 1%, 1.5%, 2%, and 2.5%. Preferably, the polymer monomer A1 includes at least two of methyl methacrylate, butyl methacrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methacrylonitrile, styrene, acrylonitrile, and methacrylonitrile.

[0060] Preferably, the crosslinking monomer A2 accounts for 1% to 5% of the mass of polymer A, including but not limited to 1%, 2%, 3%, 4%, and 5%.

[0061] Preferably, the crosslinking monomer A2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0062] Preferably, the emulsifier includes at least one selected from carboxylates, sulfates, sulfonates, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and calcium dodecylbenzene sulfonate.

[0063] Preferably, the initiator includes at least one of sodium persulfate, hydrogen peroxide, benzoyl peroxide, potassium persulfate, and persulfate.

[0064] Preferably, the mass of polymer B accounts for 25% to 50% of the mass of the non-fluoropolymer, including but not limited to 25%, 30%, 35%, 40%, 45%, and 50%.

[0065] Preferably, polymer B is polymerized from polymeric monomer B1, crosslinking monomer B2, and a small amount of additives. The additives include an initiator.

[0066] Preferably, the initiator accounts for 0.5% to 2.5% of the mass of polymer B, including but not limited to 0.5%, 1%, 1.5%, 2%, and 2.5%.

[0067] Preferably, the polymeric monomer B1 includes at least two of the following: ethyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl acrylate, n-butyl acrylate, butyl methacrylate, methyl methacrylate, methacrylonitrile, styrene, and acrylonitrile.

[0068] Preferably, the crosslinking monomer B2 accounts for 10% to 15% of the mass of polymer B, including but not limited to 10%, 11%, 12%, 13%, 14%, and 15%.

[0069] Preferably, the initiator includes at least one of sodium persulfate, hydrogen peroxide, benzoyl peroxide, potassium persulfate, and persulfate.

[0070] In this invention, the proportion of crosslinking agent in the shell layer of the non-fluoropolymer is higher than that in the core layer, thereby increasing the degree of crosslinking of the shell layer and giving the shell layer a higher elastic modulus. When the non-fluoropolymer swells at high temperature, the core layer is less likely to swell and break the shell, thus achieving the stability of the non-fluoropolymer during high-temperature swelling.

[0071] Preferably, the crosslinking monomer B2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0072] A non-fluoropolymer composite membrane comprises a base membrane and a coating layer coated on at least one side of the base membrane, the coating layer comprising the aforementioned non-fluoropolymer. Macroscopically, the coating layer can be fully coated, or dotted or striped, and microscopically, the non-fluoropolymer particles in the coating layer do not completely cover the base membrane.

[0073] Preferably, the coverage of non-fluoropolymer particles is 10% to 30%, including but not limited to 10%, 15%, 20%, 25%, and 30%, with 15% to 25% being the most preferred. The non-fluoropolymer particles in the coating layer are microscopically discontinuous.

[0074] The coverage of the non-fluoropolymer particles in this invention is 10% to 30%. If the coverage is too low, it cannot effectively block the ion conduction channels under the high temperature swelling degree of the non-fluoropolymer in this invention, and cannot suppress the chain exothermic reaction inside the cell. If the coverage is too high, the non-fluoropolymer is prone to blocking the ion conduction channels at room temperature, resulting in increased internal resistance and affecting the performance of the cell.

[0075] Preferably, the coating layer comprises at least one of the following: a (macroscopic) dotted coating layer formed by the accumulation of multiple non-fluoropolymer particles; a (macroscopic) equidistant striped coating layer formed by the accumulation of multiple non-fluoropolymer particles; or a (under a micro-electron microscope) discontinuous coating in which a single non-fluoropolymer particle or multiple non-fluoropolymer particles are connected and distributed on the base film. The preferred form is a (under a micro-electron microscope) discontinuous coating in which a single non-fluoropolymer particle or multiple non-fluoropolymer particles are connected and distributed on the base film, as shown in Figure 2. This type of discontinuous coating ensures a uniform overall distribution of the non-fluoropolymer particles, reducing the likelihood of severe local pore blockage and lithium plating problems. It can be prepared using a specific microgravure coating method, such as at least one of honeycomb microgravure or quadrilateral microgravure methods.

[0076] Preferably, the coating method for the dotted coating layer formed by the stacking of multiple non-fluoropolymers includes at least one of the following methods: rotary spraying, airflow spraying, and inkjet printing.

[0077] Preferably, the coating method for the equally spaced strip coating layer formed by stacking multiple non-fluoropolymers includes at least one method such as using a specific microgravure roller coating (the microgravure includes equally spaced coated and uncoated areas), slot extrusion coating, etc.

[0078] Preferably, the coating layer density is 0.1 g / m². 2 ~0.5g / m 2 Including but not limited to 0.1g / m 2 0.2g / m 2 0.3g / m 2 0.4g / m 2 0.5g / m 2 .

[0079] Preferably, the coating thickness is 0.4μm to 4.0μm, including but not limited to 0.4μm, 0.8μm, 1.2μm, 1.6μm, 2μm, 2.4μm, 2.8μm, 3.2μm, 3.6μm, and 4μm; preferably, a single layer of non-fluoropolymer particles is coated, and the coating thickness mainly depends on the particle size of the non-fluoropolymer.

[0080] Preferably, the coating layer further comprises an adhesive, which accounts for 1% to 6% of the mass of the non-fluoropolymer, including but not limited to 1%, 2%, 3%, 4%, 5%, and 6%.

[0081] Preferably, the adhesive includes at least one of styrene-butadiene rubber, polyacrylic acid, polyacrylamide, polyacrylonitrile, epoxy resin, polyacrylate, etc.

[0082] Preferably, the coating layer further comprises a wetting agent, which accounts for 0.1% to 1.0% of the mass of the non-fluoropolymer, including but not limited to 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%.

[0083] Preferably, the wetting agent includes at least one of alkyl sulfates, sulfonates, polyoxyethylene alkylphenol ethers, polyoxyethylene fatty alcohol ethers, alkylphenol polyoxyethylene ethers, fatty alcohol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, etc.

[0084] Preferably, the thickness of the base film is 4μm to 16μm, including but not limited to 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, and 16μm.

[0085] Preferably, the base film is one of PE base film, PP base film, or PP and PE composite base film.

[0086] The above-mentioned non-fluoropolymers and the above-mentioned non-fluoropolymer composite membranes are used in the preparation of battery cells, secondary batteries, and electrical appliances.

[0087] Example 1

[0088] A method for preparing a non-fluoropolymer composite membrane includes the following steps:

[0089] Step A, Synthesis of Core Polymer A: Take 7 parts of sodium dodecylbenzenesulfonate and 2000 parts of deionized water and put them into a reactor. Purge with nitrogen to purge the air from the reactor. Add 544.6 parts of styrene, 49.1 parts of 2-ethylhexyl acrylate and 7.4 parts of diethanol diacrylate. Use 0.5 mol / L sodium hydroxide to adjust the pH to about 8.0. Then heat and pressurize to 85℃ and 3.5 MPa. After the temperature and pressure stabilize, adjust the stirring speed to 58 rpm / min and add 6.0 parts of sodium persulfate. Polymerize at constant temperature and pressure for 4 hours. Cool down and depressurize to room temperature and atmospheric pressure (take samples to test the particle size, swelling ratio at high and low temperatures, Tg and crosslinking degree of core polymer A).

[0090] Step B, Synthesis of Shell Polymer B: Add 4 parts of sodium persulfate to the reactor, raise the temperature and pressure to 75℃ and 5MPa respectively, and when the temperature and pressure stabilize, adjust the stirring speed to 39rpm / min. Add 17.8 parts of styrene, 314.0 parts of 2-ethylhexyl acrylate and 50.2 parts of diethanol diacrylate to the reactor at a constant rate of 4.4 parts / h, 78.5 parts / h and 12.5 parts / h respectively. After the addition is complete, keep the temperature and pressure constant for 4 hours, and then cool down to room temperature and pressure to obtain a non-fluoropolymer particle emulsion (samples were taken to test the particle size, swelling ratio at high and low temperatures, Tg, degree of crosslinking and elastic modulus of the shell of the non-fluoropolymer).

[0091] Step C: Take 1.2 parts of the emulsion and dilute it with deionized water to a solid content of 20%. Then take 500 parts of the diluted non-fluoropolymer emulsion, add 3.5 parts of styrene-butadiene rubber and 0.5 parts of alkylphenol polyoxyethylene ether, stir evenly to obtain a mixed slurry. Use microgravure coating technology to form a macroscopically full coating, with single or multiple non-fluoropolymer particles connected and distributed on the base film (under a micro-electron microscope). Adjust the coating speed ratio and coat the mixed slurry onto one side of the Jieli 7μm base film. Dry it to obtain a coating layer density of 0.15g / m². 2 The composite separator was sampled and tested for coating thickness, non-fluoropolymer particle coverage, and high-temperature volume recovery coefficient of non-fluoropolymer; the composite separator and positive and negative electrode sheets were used to prepare a battery cell, and the safety performance and cycle performance of the battery cell after high-temperature treatment were tested.

[0092] Example 2

[0093] Compared to Example 1, during the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 539.7 parts, 49.1 parts, and 12.3 parts, respectively, while other parameters remained the same as in Example 1.

[0094] Example 3

[0095] Compared to Example 1, during the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in amounts of 534.8 parts, 49.1 parts, and 17.2 parts, respectively, while other parameters remained the same as in Example 1.

[0096] Example 4

[0097] Compared to Example 2, during the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 17.8 parts, 317.0 parts, and 47.1 parts, respectively, with dropping rates of 4.4 parts / h, 79.3 parts / h, and 11.8 parts / h, respectively. Other parameters were the same as in Example 2.

[0098] Example 5

[0099] Compared to Example 2, during the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 17.8 parts, 312.0 parts, and 52.1 parts, respectively, with dropping rates of 4.4 parts / h, 70.0 parts / h, and 13.0 parts / h, respectively. Other parameters were the same as in Example 2.

[0100] Example 6

[0101] Compared to Example 2, during the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken as 17.8 parts, 307.0 parts, and 57.1 parts, respectively, with dropping rates of 4.4 parts / h, 76.8 parts / h, and 14.3 parts / h, respectively, and other parameters were the same as in Example 2.

[0102] Example 7

[0103] Compared to Example 1, in the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 643.1 parts, 58.3 parts, and 14.6 parts, respectively; in the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 12.5 parts, 217.9 parts, and 36.6 parts, respectively, with dropping rates of 3.1 parts / h, 54.5 parts / h, and 9.1 parts / h, respectively. Other aspects were the same as in Example 1.

[0104] Example 8

[0105] Compared to Example 1, in the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken as 447.8 parts, 41.0 parts, and 10.2 parts, respectively; in the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken as 22.4 parts, 395.7 parts, and 65.9 parts, respectively, with dropping rates of 5.6 parts / h, 98.9 parts / h, and 16.5 parts / h, respectively, and other parameters were the same as in Example 1.

[0106] Example 9

[0107] Compared to implementation 5, the stirring speed was adjusted to 51 rpm / min during core polymer synthesis and 36 rpm / min during shell polymer synthesis. During composite membrane coating, the speed ratio was adjusted to achieve a coating layer density of 0.35 g / m². 2 The composite diaphragm is the same as in Example 5.

[0108] Example 10

[0109] Compared to implementation 5, the stirring speed was adjusted to 42 rpm / min during core polymer synthesis and 31 rpm / min during shell polymer synthesis. During composite membrane coating, the speed ratio was adjusted to achieve a coating layer density of 0.48 g / m². 2 The composite diaphragm is otherwise the same as in Example 5.

[0110] Comparative Example 1

[0111] Compared to Example 1, during the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 548.9 parts, 49.1 parts, and 3.1 parts, respectively, while other parameters remained the same as in Example 1.

[0112] Comparative Example 2

[0113] Compared to Example 1, during the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 527.4 parts, 49.1 parts, and 24.6 parts, respectively, while other parameters remained the same as in Example 1.

[0114] Comparative Example 3

[0115] Compared to Example 2, during the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 17.8 parts, 325.5 parts, and 38.6 parts, respectively, with dropping rates of 4.4 parts / h, 81.4 parts / h, and 9.6 parts / h, respectively. Other parameters were the same as in Example 2.

[0116] Comparative Example 4

[0117] Compared to Example 2, during the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 17.8 parts, 294.7 parts, and 69.5 parts, respectively, with dropping rates of 4.4 parts / h, 73.7 parts / h, and 17.4 parts / h, respectively. Other parameters were the same as in Example 2.

[0118] Comparative Example 5

[0119] Compared to Example 1, in the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 694.0 parts, 62.3 parts, and 9.3 parts, respectively; in the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were used in proportions of 10.2 parts, 179.5 parts, and 27.7 parts, respectively, with dropping rates of 2.5 parts / h, 44.9 parts / h, and 6.9 parts / h, respectively. Other aspects were the same as in Example 1.

[0120] Comparative Example 6

[0121] Compared to Example 1, in the synthesis of the core polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 370.1 parts, 33.8 parts, and 5.1 parts, respectively; in the synthesis of the shell polymer, styrene, 2-ethylhexyl acrylate, and diethanol diacrylate were taken in amounts of 26.6 parts, 475.3 parts, and 72.3 parts, respectively, with dropping rates of 6.6 parts / h, 118.8 parts / h, and 18.1 parts / h, respectively. Other parameters were the same as in Example 1.

[0122] Test case

[0123] I. Non-fluoropolymer testing; test results are shown in Table 1.

[0124] 1. Particle size test of core polymer particles and non-fluoropolymer particles: Take core polymer emulsion and non-fluoropolymer emulsion, and test the particle size with Malvern 3000 respectively. The test refractive index is 1.50, the absorptivity is 0.1, and the shading rate is 8%~18%. Finally, the particle size of core polymer particles D1 and non-fluoropolymer particles D2 are obtained.

[0125] 2. High and low temperature swelling rate test of core polymer particles and non-fluoropolymer particles: The core polymer emulsion was dried to obtain a film. A certain amount of electrolyte (EC:EMC:DEC=3:5:1, 1.0 Mol / L LiPF6) was taken into a graduated container and the electrolyte volume V1 was read. 5g of the film was added into the container and submerged in the electrolyte. The volume V2 was read again. The container was sealed and placed in a 60℃ oven for 24 hours. The film was then quickly removed and the volume V3 of the remaining electrolyte in the container was read. The swelling rate of the film at 60℃ is (V2-V3) / (V2-V1). The swelling rate of the film at a high temperature of 120℃ was measured in the same way. The high and low temperature swelling rates of non-fluoropolymers were tested in the same way.

[0126] 3. Tg test of core polymer particles and non-fluoropolymer particles: Dry the core polymer emulsion and non-fluoropolymer emulsion, weigh 5~10mg of each sample, and test the Tg using differential scanning calorimetry. Test equipment: METTLER DSC3, test temperature range: -80~150℃, heating rate: 5℃ / min. During the test, the first heating and cooling is used to eliminate thermal history, and then the Tg of the polymer is tested. After the test, the test curve is integrated to obtain Tg1 of the core polymer emulsion and Tg2-1 and Tg2-2 of the non-fluoropolymer emulsion (one of Tg2-1 and Tg2-2 is the core Tg, i.e., Tg1, and the other is the shell Tg2).

[0127] 4. Crosslinking degree test

[0128] 4.1 Crosslinking degree test of core layer polymer: Dry the core layer polymer emulsion, weigh a certain mass of film M1, immerse the film in tetrahydrofuran reagent, soak at room temperature for 72 hours, take out the film, wash the film three times with alcohol, then dry the film, weigh the mass of the dried film M2, then the crosslinking degree of the core layer polymer X1=M2 / M1.

[0129] 4.2 Test of crosslinking degree of shell polymer: Take the non-fluorinated polymer emulsion and dry it. Weigh a certain mass of film m1 (assuming the shell ratio is P, then the shell mass is P*m1, and the core mass is m1-P*m1, where P can be calculated from the total mass of the core monomers and the total mass of the shell monomers added during the synthesis of the non-fluorinated polymer). Soak the film in tetrahydrofuran reagent for 72 hours. Take out the film, wash the film with alcohol three times, and then dry the film. Weigh the mass of the dried film m2. Then the crosslinking degree of the shell polymer X2=[m2-(1-P)*m1*X1] / (P*m1).

[0130] 5. Shell elastic modulus test: The shell elastic modulus of non-fluoropolymers was tested using an FT-NMT04 in-situ nanoindenter. A Berkovich indenter was used, and the loading and unloading times were both set to 2 seconds. The relationship between load and displacement was established, and the final elastic modulus was calculated using the Oliver principle. Ten non-fluoropolymers were tested in parallel, and the final average value E was taken.

[0131] 6. High-temperature volume recovery coefficient η test of non-fluoropolymers: Take the composite membrane and take electron microscopy, and count the average particle size d1 of the non-fluoropolymer. Immerse the composite membrane in the electrode solution (EC:EMC:DEC=3:5:1, 1.0 Mol / L LiPF6), heat to 120℃, keep at the temperature for 4 hours, and then cool to room temperature. Take out the composite membrane, take electron microscopy again, and then count the average particle size d2 of the non-fluoropolymer. The high-temperature volume recovery coefficient η of the non-fluoropolymer is d2 / d1.

[0132] II. Composite membrane testing; test results are shown in Table 2.

[0133] 1. Coating thickness test: Take the base film and composite separator, select 3 points along the TD direction of the separator and 12 points along the MD direction, for a total of 36 points. Use a micrometer to measure the thickness of each point, record all data, and calculate the average value of the final result. The thickness of the base film is h1 and the thickness of the composite separator is h2. Therefore, the coating thickness = h2 - h1.

[0134] 2. Non-fluoropolymer particle coverage test of the coating layer: Take the coated composite membrane and take an electron microscope at 5000x magnification (25.6μm*19.2μm) to count the number of non-fluoropolymer particles n. Then the non-fluoropolymer particle coverage of the coating layer = 3.14*D*D*n / (4*25.6*19.2), where D is the particle size of the non-fluoropolymer.

[0135] III. Cell performance testing; test results are shown in Table 2.

[0136] 1. Safety Performance Test: The composite separator, lithium iron phosphate positive electrode, and graphite negative electrode are stacked to form the battery cell. After being fully charged, the battery is placed in an oven. The oven is heated at 10℃ / min to 110℃ and held at that temperature for 30 minutes. Then, it is heated at 1℃ / min to 120℃ and held at that temperature for 30 minutes. Finally, it is heated at 1℃ / min to 130℃ and held at that temperature for 30 minutes. If the battery cell explodes or catches fire, the battery safety performance is deemed to have failed. If the battery explodes or catches fire as the temperature rises, the experiment is terminated and the battery safety performance is deemed to have failed. The safety performance of 10 batteries is tested in parallel using the same method. The cell safety test pass rate is calculated as: (Number of batteries passing / 10) * 100%.

[0137] 2. Capacity Retention Rate Test of Battery Cells after High-Temperature Treatment: The battery cells are fabricated using a stacking process with composite separators, lithium iron phosphate positive electrode sheets, and graphite negative electrode sheets. The cells are charged at a constant current of 0.5C to 3.6V, then charged at a constant voltage of 3.6V until the current reaches 0.02C, charging is terminated, and the cells are allowed to stand for 30 minutes. They are then discharged at a constant current of 0.5C to 2.0V, discharged, and allowed to stand for 30 minutes. The first discharge capacity is recorded. After discharge, the cells are placed in a 120℃ oven and baked for 1 hour. They are then removed and allowed to stand for 24 hours. The cells are then cycled 300 times using the same parameters as the first cycle. The discharge capacity of the 300th cycle is recorded. The ratio of the 300th cycle discharge capacity to the first cycle discharge capacity is the capacity retention rate of the battery cells after 300 cycles of high-temperature treatment.

[0138] Table 1. Relevant performance data of non-fluoropolymers

[0139]

[0140] Table 2 Performance data of non-fluoropolymer coated composite membrane and battery cell

[0141]

[0142] The non-fluoropolymers designed in the embodiments of this invention have all the properties within the scope of protection claimed by this invention. The non-fluoropolymers exhibit high swelling performance at high temperatures. When the non-fluoropolymer is coated on a separator and fabricated into a battery cell, the rapid swelling of the non-fluoropolymer during abnormal temperature rise can block ion shuttle channels, preventing further deterioration of the battery cell temperature and improving the high-temperature safety performance of the battery cell. The shell layer has a high degree of cross-linking, resulting in a high elastic modulus, which can restrain the stress generated by the high-temperature swelling of the core polymer, preventing the shell layer from being squeezed and collapsing. When the temperature returns to room temperature / room temperature, the core polymer shrinks after releasing the electrolyte, and the shell polymer can recover its original morphology, giving the non-fluoropolymer a small high-temperature volume recovery coefficient, which has no impact on subsequent battery cell cycle performance. The thickness of the non-fluoropolymer shell layer is set within a suitable range to ensure the integrity of the non-fluoropolymer and its high-temperature swelling performance.

[0143] When the cross-linking degree of the non-fluoropolymer core polymer is relatively small, the swelling rate of the core polymer is relatively large at low and high temperatures. The stress released by high-temperature swelling can easily rupture the shell polymer, causing the core polymer to overflow and the polymer as a whole to collapse. Although this can improve the high-temperature safety performance of the cell, due to its high high-temperature volume recovery coefficient, the ion channels are severely blocked after the cell is treated at high temperature, and the subsequent cycle performance is severely reduced. When the cross-linking degree of the core polymer is high, the overall swelling rate of the polymer decreases at high temperature. When the cell is abnormally heated, most of the ion channels are still not blocked, and the cell safety performance deteriorates significantly, as shown in Comparative Examples 1 and 2.

[0144] When the cross-linking degree of the non-fluoropolymer shell polymer is relatively small, the elastic modulus of the shell polymer is relatively low. At high temperatures, the stress generated by the rapid swelling of the core polymer can easily cause the shell polymer to break, leading to the collapse of the non-fluoropolymer. Although this can improve the high-temperature safety performance of the cell, due to its high high-temperature volume recovery coefficient, the ion channels are severely blocked after the cell is treated at high temperatures, resulting in a significant decrease in subsequent cycle performance. When the cross-linking degree of the shell polymer is high, the elastic modulus of the shell polymer is relatively high, which can easily restrict the swelling of the core polymer at high temperatures, leading to a decrease in the overall swelling rate of the non-fluoropolymer at high temperatures. When the cell is abnormally heated, most of the ion channels are still not blocked, and the cell safety performance deteriorates significantly, as shown in Comparative Examples 3 and 4.

[0145] When the non-fluoropolymer shell thickness is relatively small, the stress generated by the high-temperature swelling of the core layer can easily cause the shell to break and collapse. Although this can improve the high-temperature safety performance of the cell, due to its high high-temperature volume recovery coefficient, the ion channels are severely blocked after the cell is treated at high temperature, resulting in a significant decrease in subsequent cycle performance. When the shell thickness is too high, the binding force of the shell increases, which hinders the high-temperature swelling of the core layer. The overall swelling rate of the non-fluoropolymer at high temperature is low. When the cell is abnormally heated, most of the ion channels are still not blocked, and the cell safety performance deteriorates significantly, as shown in Comparative Examples 5 and 6.

Claims

1. A non-fluoropolymer for use in composite membranes, characterized in that, The polymer comprises polymer A and polymer B at least partially coated on the surface of polymer A. The degree of crosslinking of polymer A is X1, and the degree of crosslinking of polymer B is X2, where 5% ≤ X1 ≤ 10% and 50% ≤ X2 ≤ 60%. The glass transition temperature of polymer A is Tg1, and the glass transition temperature of polymer B is Tg2, where 100℃ ≤ Tg1 ≤ 110℃ and -10℃ ≤ Tg2 ≤ 10℃. The overall swelling rate of the non-fluoropolymer at 60℃ is 30%~80%, and the overall swelling rate at 120℃ is 500%~600%. The high-temperature volume recovery coefficient η of the non-fluoropolymer is 1 ≤ η ≤ 1.

5.

2. The non-fluoropolymer according to claim 1, characterized in that, The non-fluoropolymer includes a core layer and a shell layer at least partially covering the surface of the core layer, the core layer comprising polymer A and the shell layer comprising polymer B.

3. The non-fluoropolymer according to claim 2, characterized in that, The elastic modulus of the shell is E, where 5MPa≤E≤15MPa.

4. The non-fluoropolymer according to claim 2, characterized in that, It includes at least one of the following technical features: (1) the particle size of the non-fluoropolymer is 0.4μm~4.0μm; (2) the ratio of the total thickness of the shell layer to the particle size of the non-fluoropolymer is N, 10%≤N≤20%; (3) the swelling rate of the core layer at 60℃ is 20%~50%, and the swelling rate at 120℃ is 450%~550%.

5. The non-fluoropolymer according to claim 2 or 4, characterized in that, It includes at least one of the following technical features: (1) the mass of polymer A accounts for 50% to 75% of the mass of the non-fluoropolymer; (2) the mass of polymer B accounts for 25% to 50% of the mass of the non-fluoropolymer; (3) polymer A is polymerized from polymeric monomer A1 and crosslinking monomer A2; the crosslinking monomer A2 accounts for 1% to 5% of the mass of polymer A; (4) polymer B is polymerized from polymeric monomer B1 and crosslinking monomer B2; the crosslinking monomer B2 accounts for 10% to 15% of the mass of polymer B.

6. The non-fluoropolymer according to claim 5, characterized in that, It includes at least one of the following technical features: (1) The polymeric monomer A1 includes at least two of methyl methacrylate, butyl methacrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methacrylonitrile, styrene, acrylonitrile, and methacrylonitrile; (2) The crosslinking monomer A2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane; (3) The polymeric monomer B1 includes at least two of ethyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl acrylate, n-butyl acrylate, butyl methacrylate, methyl methacrylate, methacrylonitrile, styrene, and acrylonitrile; (4) The crosslinking monomer B2 includes at least one of divinylbenzene, diallyl phthalate, diethanol diacrylate, trimethylolpropane trimethacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

7. A non-fluoropolymer composite separator, comprising a base film and a coating layer coated on at least one side of the base film, said coating layer comprising the non-fluoropolymer as described in any one of claims 1 to 6, characterized in that, It includes at least one of the following technical features: (1) the coverage of the non-fluoropolymer particles is 10%~30%; (2) the density of the coating layer is 0.1g / m². 2 ~0.5g / m 2 (3) The coating thickness is 0.4μm~4.0μm; (4) The base film thickness is 4μm~16μm; (5) The base film is one of PE base film, PP base film, or PP and PE composite base film.

8. The non-fluoropolymer composite membrane according to claim 7, characterized in that, The coating layer includes at least one of the following technical features: (1) the coating layer further includes an adhesive, the adhesive accounting for 1% to 6% of the mass of the non-fluoropolymer; the adhesive includes at least one of styrene-butadiene rubber, polyacrylic acid, polyacrylamide, polyacrylonitrile, epoxy resin, and polyacrylate; (2) the coating layer further includes a wetting agent, the wetting agent accounting for 0.1% to 1.0% of the mass of the non-fluoropolymer; the wetting agent includes at least one of alkyl sulfate, sulfonate, polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and fatty acid polyoxyethylene ether.

9. The application of the non-fluoropolymer as described in any one of claims 1 to 6, or the non-fluoropolymer composite membrane as described in claim 7 or 8, characterized in that, The applications are in the manufacture of battery cells, secondary batteries, and electrical appliances.

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