Low-closed-pore high-temperature-resistant lithium battery separator and preparation method and device thereof

Abstract

The present disclosure provides a low-closed-pore high-temperature-resistant lithium battery diaphragm and a preparation method and device thereof, and relates to the technical field of lithium batteries, which comprises the following steps: uniformly mixing ester monomers, polymerization inhibitors and surfactants, dissolving them in a polar solvent, and conveying them to a first flow box; controlling the nozzle size and liquid pressure of the first flow box to uniformly spray them onto a PE diaphragm; performing electron beam irradiation modification on the PE diaphragm; performing water washing through a flat-width washing machine and drying; adding aramid short fibers to a potassium hydroxide and DMSO solution for continuous stirring to obtain an ANF / DMSO dispersion liquid; conveying the dispersion liquid to a second flow box to spray the electron beam irradiation modified PE diaphragm; conveying the diaphragm sprayed with the ANF / DMSO dispersion liquid to a spraying device for protonation reduction; drying the ANF hydrogel / modified PE diaphragm through an electromagnetic heating roller, and winding to obtain a lithium battery diaphragm. The present disclosure can reduce the closed-pore temperature of the diaphragm, and at the same time, improve the thermal stability and mechanical properties of the diaphragm.

Description

Technical Field

[0001] This disclosure relates to the field of lithium battery technology, specifically to a method for preparing a low-closed-pore, high-temperature resistant lithium battery separator, a low-closed-pore, high-temperature resistant lithium battery separator, and an apparatus for preparing the low-closed-pore, high-temperature resistant lithium battery separator. Background Technology

[0002] As the global energy structure accelerates its transition towards cleaner and lower-carbon energy, lithium-ion batteries, with their core advantages such as high energy density and long cycle life, have become the core power source for new energy vehicles, large-scale energy storage power stations, and high-end consumer electronics products. The separator, as a crucial inner component of the battery, bears the dual responsibility of isolating the positive and negative electrodes to prevent short circuits while ensuring efficient lithium-ion transport. Its thermal stability and safety protection functions directly determine the overall safety boundary of the battery system.

[0003] Currently, commercially available lithium-ion batteries widely use polyolefin-based separators, such as PP, PE, and their composite multilayer films. However, traditional polyolefin separators generally have high pore-closing temperatures. When the battery's internal temperature rises due to abuse, the separator cannot effectively and promptly seal the micropores at the early critical stage of accelerated thermal runaway chain reactions, thus blocking current and causing the exothermic reaction to continue to intensify. Polyolefin materials have low melting points and severe thermal shrinkage at high temperatures. Once the temperature exceeds its melting point or softening point, the separator will undergo large-area melting, collapse, and violent shrinkage, resulting in direct contact between extremely large positive and negative areas, triggering a catastrophic internal short circuit and releasing enormous energy instantaneously.

[0004] To improve heat resistance, related technologies involve coating the membrane surface with inorganic ceramic particles such as alumina and boehmite to form a ceramic coating membrane. However, this approach cannot simultaneously solve the problems of low-temperature pore closure and high-temperature heat resistance, and it also affects ionic conductivity, increases interfacial impedance, and impacts battery rate and cycle performance. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method for preparing a low-closed-cell, high-temperature resistant lithium battery separator, a low-closed-cell, high-temperature resistant lithium battery separator, and an apparatus for preparing a low-closed-cell, high-temperature resistant lithium battery separator, thereby overcoming, to at least a certain extent, the problem of poor performance of lithium battery separators caused by limitations and defects in related technologies.

[0006] According to one aspect of this disclosure, a method for preparing a low-closed-pore, high-temperature resistant lithium battery separator is provided, comprising: uniformly mixing an ester monomer, a polymerization inhibitor, and a surfactant, dissolving them in a polar solvent, diluting them proportionally to obtain a composite monomer solution, placing the composite monomer solution in a first stirring tank and conveying it to a first headstock tank via a headstock pump; controlling the nozzle size and spray pressure of the first headstock tank to uniformly spray the composite monomer solution onto a PE separator; conveying the PE separator coated with the composite monomer solution to an electron beam irradiation device via a conveyor roller, and using the electron beam irradiation device to modify the PE separator coated with the composite monomer solution by electron beam irradiation to obtain an electron beam irradiated modified PE separator; and passing the electron beam irradiated modified PE separator through a flat-web washing machine. The aramid chopped fibers are washed with water and then transferred to a drying cylinder for drying. Aramid short-cut fibers are placed in a second mixing tank, and potassium hydroxide and DMSO solutions are added and continuously stirred to obtain an ANF / DMSO dispersion. The ANF / DMSO dispersion is transferred to a second headbox, and the nozzle size of the second headbox is controlled to spray the electron beam-modified PE separator, resulting in a separator coated with the ANF / DMSO dispersion. The separator coated with the ANF / DMSO dispersion is then transferred to a spraying device via a conveyor roller, where it is protonated and reduced to form an ANF hydrogel / modified PE separator. The ANF hydrogel / modified PE separator is then transferred to an electromagnetically heated roller for drying and wound up to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0007] In one exemplary embodiment of this disclosure, the mass ratio of ester monomer, polymerization inhibitor and surfactant is (96~99):(2.5~0.5):(1.5~0.5), and the concentration of the composite monomer solution is 10%~60%.

[0008] In one exemplary embodiment of this disclosure, the ester monomer is one or more of ethyl acrylate, isooctyl acrylate, lauryl methacrylate, isobutyl acrylate, and lauryl acrylate; the polymerization inhibitor is one or more of 2,6-di-tert-butyl-p-cresol, hydroquinone, and p-benzoquinone; the surfactant is one or a mixture of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and polyglycerol-10 oleate; and the polar solvent is one or more of acetone, ethanol, or water.

[0009] In one exemplary embodiment of this disclosure, the nozzle size of the first headbox is 0.1~2 mm, the spray pressure is 0.01~0.2 MPa, and the spray rate is 0.01~0.2 L / min; the nozzle size of the second headbox is 0.1~2 mm, the spray pressure is 0.01~0.2 MPa, and the spray rate is 0.01~0.2 L / min.

[0010] In one exemplary embodiment of this disclosure, the energy of the electron beam irradiation is 50~5000 keV, and the irradiation dose is 10~500 kGy.

[0011] In one exemplary embodiment of this disclosure, the length of the aramid chopped fibers is 1 to 5 mm, and the concentration of the ANF / DMSO dispersion is 0.1% to 5%.

[0012] In one exemplary embodiment of this disclosure, the nozzle size of the spraying device is 0.1~1 mm, the spray pressure is 0.01~0.5 MPa, and the spray rate is 0.01~0.1 L / min.

[0013] In one exemplary embodiment of this disclosure, the temperature of the electromagnetic heating roller is 30~50°C.

[0014] According to one aspect of this disclosure, a low-closed-cell, high-temperature resistant lithium battery separator is provided, which is prepared according to the above-described method for preparing a lithium battery separator.

[0015] According to one aspect of this disclosure, an apparatus for preparing a low-closed-cell, high-temperature resistant lithium battery separator is provided. The apparatus prepares the low-closed-cell, high-temperature resistant lithium battery separator by the aforementioned method. The apparatus includes: a first mixing tank, a headstock pump, a first headbox, a nozzle, an electron beam irradiation device, a flat-web washing machine, a drying cylinder, a second mixing tank, a second headbox, a conveying roller, a spraying device, an electromagnetic heating roller, and a winding roller.

[0016] In the technical solutions provided in this disclosure, on the one hand, the thermal stability of the separator is significantly improved by introducing an aramid nanofiber (ANF) coating onto the electron beam irradiation modified PE separator. Aramid materials themselves have extremely high thermal decomposition temperatures, and the formed ANF coating can effectively block direct contact between the positive and negative electrodes at high temperatures, preventing thermal runaway. The prepared separator can withstand higher temperatures, greatly improving the safety performance of lithium batteries under extreme or abusive conditions. ANF modification enhances the separator's high-temperature resistance, dimensional stability, and mechanical properties, reducing the risk of high-temperature shrinkage. On the other hand, electron beam irradiation technology stimulates the generation of free radicals in the amorphous regions of PE, initiating the graft polymerization of ester monomers, effectively grafting ester monomers onto the PE separator. Flexible branches widen the spacing between PE molecular chains, significantly reducing the energy barrier for chain segment movement in the amorphous regions. When heated, the highly mobile branches move first, effectively blocking the pores of the PE separator, thereby significantly reducing the pore-closing temperature. In the early stages of abnormally high internal battery temperatures, it can more quickly close micropores, block ion transport, effectively suppress exothermic reactions, prevent thermal runaway, and provide earlier and more critical protection for battery safety. Furthermore, grafted ester monomers significantly reduce the electrolyte contact angle and greatly improve wettability, further improving ionic conductivity and reducing battery internal resistance. The ANF coating also improves electrolyte wettability and retention capacity, which is beneficial for enhancing ionic conductivity and battery cycle life and rate performance. On the other hand, by precisely controlling the spraying parameters of the composite monomer solution and the spraying thickness of the ANF / DMSO dispersion, and by using a spraying technique to protonate and reduce the ANF coating, the excessive cross-linking caused by electron beam irradiation and the excessive blockage of the original micropores of the PE base film by the ANF coating are effectively avoided. This allows the final separator to achieve excellent high-temperature resistance while maintaining low air permeability, ensuring sufficient wetting of the electrolyte and efficient lithium-ion transport channels. This optimizes the battery's ionic conductivity, rate performance, and cycle life, overcoming the shortcomings of traditional thick coatings or ceramic coatings that easily lead to high air permeability and increased internal resistance.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] Figure 1 The flowchart illustrates a method for preparing a low-closed-pore, high-temperature resistant lithium battery separator according to an embodiment of this disclosure.

[0020] Figure 2 This is a schematic diagram of an automated, continuous production line for low-closed-pore, high-temperature resistant lithium battery separators.

[0021] Figure 3 It is the DSC of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1.

[0022] Figure 4 This is a TEM image of the aramid nanofibers (ANF) prepared in Example 1.

[0023] Figure 5 This is a photograph of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1.

[0024] Figure 6 This is a SEM image of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1.

[0025] Figure 7 This is a comparison of the thermal shrinkage properties of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1 and the base film.

[0026] Figure 8 This is a comparison of the wettability of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1 with the base film.

[0027] Figure 9 This is a physical image of a lithium battery separator prepared in proportion.

[0028] Figure 10 This is a comparison chart of the thermal shrinkage properties of the lithium battery separator and the base film prepared in a comparative proportion.

[0029] Figure 11 This is a comparison chart of the wetting properties of the lithium battery separator and the base film prepared in a comparative proportion. Detailed Implementation

[0030] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of these specific details omitted, or other methods, components, apparatus, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0031] The terms “a,” “an,” “the,” and “the” are used in this specification to indicate the presence of one or more elements / components, etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components, etc., in addition to those listed; the terms “first” and “second” are used only as markings and are not a limitation on the number of objects.

[0032] Currently, the polyolefin-based separators (such as PP, PE, and their composite multilayer films) widely used in commercial lithium batteries have inherent thermal performance defects that severely restrict the improvement of battery safety. On the one hand, the pore-closing temperature of traditional polyolefin separators is generally high (approximately 140°C for PE and over 160°C for PP). When the battery begins to heat up due to abuse (such as overcharging, internal short circuits, and compression), the separator cannot effectively and timely close the micropores at the early critical node of the accelerated thermal runaway chain reaction (usually below 130°C), thus blocking the current and causing the exothermic reaction to continue to intensify. On the other hand, polyolefin materials have low melting points (approximately 135°C for PE and 165°C for PP) and severe thermal shrinkage at high temperatures (e.g., shrinkage rate can exceed 40% at 160°C). Once the temperature exceeds its melting point or softening point, the separator will undergo large-area melting, collapse, and violent shrinkage, resulting in direct contact between the positive and negative surfaces, triggering a catastrophic internal short circuit and releasing enormous energy instantaneously. To improve heat resistance, inorganic ceramic particles such as alumina and boehmite are coated on the surface of the separator (forming a ceramic-coated separator). This strategy can suppress the high-temperature shrinkage of the separator to a certain extent (e.g., the shrinkage rate drops to <5% at 160℃), but it has significant limitations: the ceramic coating has weak adhesion to the polyolefin matrix and is easy to fall off, and the coating itself does not have a thermal shut-off function, so it cannot solve the fundamental safety shortcoming of excessively high pore temperature; more importantly, the dense and rigid ceramic layer may significantly degrade the wettability and ionic conductivity of the separator, increase the interfacial impedance, and affect the battery rate and cycle performance.

[0033] In related technologies, coating a membrane by mixing the polymer solution of a low-melting-point polymer with the polymer solution of a heat-resistant polymer can simultaneously and significantly increase the membrane rupture temperature and reduce the pore-closing temperature. However, this method inevitably reduces the permeability of the membrane itself and affects the ionic conductivity. Heat-resistant polymers need to be processed under nitrogen protection and in an ice-water bath. The reaction conditions are harsh and the generation of byproducts is unavoidable. This not only affects other properties of the membrane but also makes it difficult to achieve industrial production.

[0034] The preparation process of high-temperature aramid coated lithium-ion battery separators can make up for the low tensile strength of non-woven separators. However, this process cannot achieve pore closure at low temperatures in the early stage of thermal runaway, effectively blocking ion transport and electrochemical reaction exothermics to delay or prevent large-scale internal short circuits. This can easily lead to the continuous aggravation of exothermic reactions and trigger global runaway.

[0035] To address the aforementioned technical problems, this disclosure provides a method for preparing a low-closed-pore, high-temperature resistant lithium battery separator, used for preparing a lithium battery separator for use in lithium batteries. (Reference) Figure 1 As shown, the preparation method of this low-closed-pore, high-temperature resistant lithium battery separator mainly includes the following steps:

[0036] In step S110, the ester monomer, polymerization inhibitor and surfactant are mixed evenly and then dissolved in a polar solvent. After being diluted in proportion, a composite monomer solution is obtained. The composite monomer solution is placed in the first stirring tank and conveyed to the first headbox by the headbox pump.

[0037] In step S120, the nozzle size and spray pressure of the first headbox are controlled so that the composite monomer solution is uniformly sprayed onto the PE membrane.

[0038] In step S130, the PE diaphragm coated with the composite monomer solution is conveyed to the electron beam irradiation equipment via a conveyor roller. The electron beam irradiation equipment is used to modify the PE diaphragm coated with the composite monomer solution by electron beam irradiation to obtain the electron beam irradiated modified PE diaphragm.

[0039] In step S140, the electron beam irradiated modified PE membrane is washed with water by a flat-width washing machine and then transferred to a drying cylinder for drying.

[0040] In step S150, aramid short-cut fibers are placed in a second mixing tank, and potassium hydroxide and DMSO solution are added and continuously stirred to obtain an ANF / DMSO dispersion.

[0041] In step S160, the ANF / DMSO dispersion is transferred to the second headbox, and the nozzle size of the second headbox is controlled to spray the electron beam irradiated modified PE membrane to obtain a membrane sprayed with the ANF / DMSO dispersion.

[0042] In step S170, the membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by the conveying roller, so that the membrane coated with ANF / DMSO dispersion is protonated and reduced to form ANF hydrogel / modified PE membrane.

[0043] In step S180, the ANF hydrogel / modified PE separator is transferred to an electromagnetic heating roller for drying and then wound up to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0044] The technical solutions in this embodiment ensure that the composite monomer solution can be uniformly sprayed onto the PE diaphragm by controlling the nozzle size and spray volume of the first headbox; the PE diaphragm is modified by electron beam irradiation and grafted with ester monomers on its surface, ensuring that its thickness and air permeability remain unchanged while significantly reducing the diaphragm's closed-cell temperature; the multi-tank countercurrent design of the flat-width washing machine saves water and chemicals and can efficiently remove impurities, greatly improving production efficiency; the use of waste aramid fibers reduces the diaphragm's production cost; the ANF / DMSO solution sprayed onto the diaphragm surface is continuous and uniform by controlling the nozzle size and spray volume of the second headbox; the spraying device allows for direct protonation reduction, eliminating the solvent exchange step; and the temperature of the electromagnetic heating roller is controlled to ensure that the diaphragm dries without shrinking. The above technical solution enables rapid softening, melting, and effective sealing of microporous channels when the internal temperature of the battery rises abnormally to a level significantly lower than the melting point of traditional polyolefins, thus cutting off the ion flow in a timely manner and providing "early melting" protection. At the same time, it maintains excellent dimensional stability and mechanical strength under extreme high temperature conditions (>200℃), effectively resisting high-temperature thermal shrinkage and melt fracture, and providing a solid physical isolation barrier for the battery.

[0045] Next, the preparation method of the lithium battery separator in the embodiments of this disclosure will be described in detail. The preparation method of the lithium battery separator is realized by a lithium battery separator preparation device. (Reference) Figure 1 As shown, the equipment for preparing a lithium battery separator includes: a first mixing tank 1, a sizing pump 2, a first headbox 3, a nozzle 4, an electron beam irradiation device 5, a flat-web washing machine 6, a drying cylinder 7, a second mixing tank 8, a sizing pump 9, a second headbox 10, a conveyor roller 11, a spraying device 12, an electromagnetic heating roller 13, and a take-up roller 14. The first headbox 3, the electron beam irradiation device 5, the second headbox 10, and the spraying device 12 are located on the upper side of the separator; the electron beam irradiation device 5 is located near the nozzle 4 of the first headbox 3; the second headbox 10 is located on the upper side of the separator between the drying cylinder 7 and the conveyor roller 11; the spraying device 12 is located on the upper side of the separator between the conveyor roller 11 and the electromagnetic heating roller 13; the flat-web washing machine 6, the drying cylinder 7, the conveyor roller 11, the electromagnetic heating roller 13, and the take-up roller 14 are located on the lower side of the separator. The first mixing tank 1 is connected to the first headbox 3 via a headstock pump 2, and the surface of the first headbox 3 has multiple nozzles 4. The second mixing tank 8 is connected to the second headbox 10 via a headstock pump 9. The above-described apparatus for preparing low-closed-cell, high-temperature resistant lithium-ion battery separators can automatically achieve continuous, large-scale, and mass production of low-closed-cell, high-temperature resistant lithium-ion battery separators, avoiding the cost and time-consuming nature of manual labor, thereby meeting practical application requirements.

[0046] In step S110, the ester monomer, polymerization inhibitor and surfactant are mixed evenly and then dissolved in a polar solvent. After dilution, a composite monomer solution is obtained. The composite monomer solution is placed in the first stirring tank and conveyed to the first headbox by the headstock pump.

[0047] In this embodiment, the ester monomer is one or more of ethyl acrylate, isooctyl acrylate, lauryl methacrylate, isobutyl acrylate, and lauryl acrylate; the polymerization inhibitor is one or more of 2,6-di-tert-butyl-p-cresol, hydroquinone, and p-benzoquinone; the surfactant is one or a mixture of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and polyglycerol-10 oleate; and the polar solvent is one or more of acetone, ethanol, or water.

[0048] The mass ratio of ester monomers, polymerization inhibitors, and surfactants can be (96~99):(2.5~0.5):(1.5~0.5). The concentration of the composite monomer solution obtained after proportional dilution is 10%~60%. By controlling the mass ratio of ester monomers to polymerization inhibitors and surfactants, the effective and uniform grafting of ester monomers onto the PE chains can be maximized while minimizing the negative impact on the basic properties of the PE separator, such as strength, porosity, permeability, and chemical stability. This results in a significant reduction in the pore-closing temperature and improved battery safety. By mixing ester monomers with polymerization inhibitors and surfactants, precise grafting of ester monomers into the interior of the PE separator can be achieved during electron beam irradiation, avoiding cross-linking of the PE separator itself.

[0049] After being diluted proportionally to obtain a composite monomer solution, the composite monomer solution is placed in a first stirring tank 1 and conveyed to a first headbox 3 via a headbox pump 2. The surface of the first headbox 3 has multiple nozzles 4.

[0050] Step S120: Control the nozzle size and spray pressure of the first headstock box so that the composite monomer solution is evenly sprayed onto the PE membrane.

[0051] In this embodiment, the nozzle size of the first headbox is 0.1~2 mm, the spray pressure is 0.01~0.2 MPa, and the spray rate is 0.01~0.2 L / min. By controlling the nozzle size and spray pressure of the first headbox, the composite monomer solution can be uniformly sprayed onto the surface of the PE membrane, thereby enabling the monomer to be effectively grafted into the entire membrane.

[0052] In step S130, the PE diaphragm coated with the composite monomer solution is conveyed to the electron beam irradiation equipment via a conveyor roller. The electron beam irradiation equipment is used to modify the PE diaphragm coated with the composite monomer solution by electron beam irradiation to obtain the electron beam irradiated modified PE diaphragm.

[0053] In this embodiment, a PE diaphragm coated with a composite monomer solution is conveyed via a conveyor roller 11 to an electron beam irradiation device 5 for electron beam irradiation modification. The electron beam irradiation energy is 50~5000 keV, and the irradiation dose is 10~500 kGy. By controlling the electron beam irradiation energy and dose, the electron penetration depth and cross-linking degree can be controlled, maximizing the modification effect while avoiding degradation, embrittlement, and unnecessary cost increases caused by excessive irradiation.

[0054] Step S140: The electron beam irradiated modified PE membrane is washed with water using a flat-width washing machine and then transferred to a drying cylinder for drying.

[0055] In this embodiment, the electron beam-modified PE membrane is conveyed to a flat-web washing machine 6 via a conveyor roller 11 for washing, and then to a drying cylinder 7 for drying. The washing and drying times can be determined according to actual needs. The flat-web washing machine, through the synergistic effect of spraying, rinsing, and counter-current washing, can continuously and thoroughly remove residual monomers and surface homopolymers from the membrane, with a mechanical cleaning effect far superior to static immersion. Simultaneously, the equipment's low-tension control system perfectly maintains the flatness and geometric dimensions of the film, avoiding wrinkles and stretching deformation. This not only enables a crucial leap from intermittent laboratory operation to continuous industrial production, significantly improving efficiency, but also, through a water-saving and environmentally friendly counter-current design, ultimately ensures the purity, stability, and uniformity of the modified film product's performance.

[0056] In step S150, aramid short-cut fibers are placed in a second mixing tank, and potassium hydroxide and DMSO solution are added and continuously stirred to obtain an ANF / DMSO dispersion.

[0057] In this embodiment, the aramid chopped fibers can be waste para-aramid chopped fibers. The length of the aramid chopped fibers is 1-5 mm. The aramid chopped fibers are placed in a second stirring tank 8, and potassium hydroxide and DMSO solutions are added and continuously stirred for 4 hours or other suitable times, ensuring uniform mixing to obtain an aramid nanofiber (ANF) / DMSO dispersion. The amount of potassium hydroxide and DMSO solution added can be determined according to actual needs, as long as the concentration of the ANF / DMSO dispersion is maintained at 0.1%-5%. By controlling the length of the aramid chopped fibers, the preparation cycle of the ANF / DMSO dispersion can be significantly reduced, and controlling the concentration of the ANF / DMSO dispersion can ensure more uniform spraying and avoid nozzle clogging.

[0058] In step S160, the ANF / DMSO dispersion is transferred to the second headbox, and the nozzle size of the second headbox is controlled to spray the electron beam irradiated modified PE membrane to obtain a membrane sprayed with the ANF / DMSO dispersion.

[0059] The second headbox 10 has a nozzle size of 0.1~2 mm, a spray pressure of 0.01~0.2 MPa, and a spray rate of 0.01~0.2 L / min. By controlling the nozzle size and spray pressure of the second headbox, the dispersion can be uniformly sprayed onto the electron beam irradiated modified PE membrane, resulting in a PE membrane coated with an ANF / DMSO dispersion. Controlling the nozzle size and spray pressure of the second headbox allows for a thinner and more uniform coating of the ANF / DMSO dispersion on the surface of the electron beam irradiated modified PE membrane, thus ensuring that its original air permeability remains unchanged. The thickness can be determined and adjusted according to industrial requirements.

[0060] In step S170, the membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by a conveyor roller, so that the membrane coated with ANF / DMSO dispersion is protonated and reduced to form an ANF hydrogel / modified PE membrane.

[0061] In this embodiment, the membrane coated with ANF / DMSO dispersion is conveyed to the spraying device 12 via a conveyor roller 11. The spraying device 12 sprays a protonating solvent, such as water, ethanol, methanol, or ethylene glycol, causing the membrane coated with ANF / DMSO dispersion to be protonated and reduced upon contact with the protonating solvent, forming an ANF hydrogel / modified PE membrane. The nozzle size of the spraying device is 0.1~1 mm, the spraying pressure is 0.01~0.5 MPa, and the spraying rate is 0.01~0.1 L / min. By controlling the nozzle size and spraying pressure of the spraying device, the ANF / DMSO dispersion sprayed onto the surface of the modified PE membrane can be rapidly protonated without being dispersed, ensuring uniform thickness.

[0062] In step S180, the ANF hydrogel / modified PE separator is transferred to an electromagnetic heating roller for drying and then wound up to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0063] In this process, the ANF hydrogel / modified PE separator is conveyed to the electromagnetic heating roller 13 via the conveyor roller 11 for drying. The temperature of the electromagnetic heating roller is 30~50℃, i.e., the drying temperature is 30~50℃. After drying, it is wound up by the winding roller 14 to obtain a low-closed-cell, high-temperature resistant lithium battery separator. By controlling the temperature of the electromagnetic heating roller, it is ensured that the separator will not shrink or deform during rapid drying, thus maintaining its integrity.

[0064] In this embodiment, the thermal stability of the PE separator is significantly improved by introducing an aramid nanofiber (ANF) coating onto the electron beam irradiation modified PE separator. Aramid materials themselves have extremely high thermal decomposition temperatures (>500℃), and the resulting ANF coating effectively prevents direct contact between the positive and negative electrodes at high temperatures, thus preventing thermal runaway. Compared to traditional PE separators which experience severe shrinkage and melting leading to short circuits at around 130℃, the prepared separator can withstand temperatures far exceeding this (>200℃), greatly improving the safety performance of lithium batteries under extreme operating conditions or abuse.

[0065] Electron beam irradiation technology is used to stimulate the generation of free radicals in the amorphous regions of PE, initiating the graft polymerization of ester monomers and effectively grafting them onto the PE separator. Flexible side chains act like "molecular wedges," widening the spacing between PE molecular chains and significantly reducing the energy barrier for chain movement in the amorphous regions. Upon heating, these highly mobile side chains move first, effectively blocking the pores of the PE separator, thus significantly reducing the pore-closing temperature (down to 120℃, far lower than PE's 140℃). In the early stages of abnormal temperature increases inside the battery (such as short circuits), they can more quickly close micropores, blocking ion transport, effectively suppressing exothermic reactions, preventing thermal runaway, and providing an earlier and more critical "fuse" for battery safety. Furthermore, grafting ester monomers significantly reduces the electrolyte contact angle and greatly improves wettability, further improving ionic conductivity and reducing battery internal resistance. Simultaneously, ANF modification enhances the separator's high-temperature resistance, dimensional stability, and mechanical properties, reducing the risk of high-temperature shrinkage. In addition, the ANF coating can improve the wettability and liquid retention of the electrolyte, which is beneficial to improving the ionic conductivity and the cycle life and rate performance of the battery. It can significantly improve the safety of the battery while also ensuring good electrochemical performance.

[0066] Precise control of the nozzle size and spraying pressure of the composite monomer solution, as well as the spraying thickness of the ANF / DMSO dispersion, and the use of a spraying technique for protonation reduction to form the ANF coating, effectively avoids excessive cross-linking due to electron beam irradiation and excessive clogging of the original micropores of the PE base film by the ANF coating. This results in a final separator that achieves excellent high-temperature resistance while maintaining low air permeability, ensuring sufficient electrolyte wetting and efficient lithium-ion transport channels. This optimizes the battery's ionic conductivity, rate performance, and cycle life, overcoming the drawbacks of traditional thick coatings or ceramic coatings that tend to lead to high air permeability and increased internal resistance.

[0067] By using waste para-aramid chopped fibers as raw materials and preparing ANF dispersion through alkali (potassium hydroxide) / DMSO solution dissolution and regeneration, high-value utilization of waste resources is achieved, significantly reducing the raw material cost of high-performance aramid-coated membranes. Compared with traditional aramid membrane preparation processes that rely on high-purity, high-cost aramid resins, this method has outstanding economic and environmental advantages in terms of raw material sourcing.

[0068] The flat-web washing machine, through the synergistic effects of spraying, rinsing, and countercurrent washing, can continuously and thoroughly remove residual monomers and surface homopolymers from the membrane, achieving a mechanical cleaning effect far superior to static immersion. Simultaneously, the equipment's low-tension control system perfectly maintains the flatness and dimensional stability of the film, preventing wrinkles and stretching deformation. This not only enables a crucial leap from intermittent laboratory operation to continuous industrial production, significantly improving efficiency, but also, through its water-saving and environmentally friendly countercurrent design, ultimately ensures the purity, stability, and uniformity of the modified film product's performance.

[0069] This invention provides a complete continuous roll-to-roll production process, efficiently integrating key steps such as ester monomer solution spraying, electron beam irradiation modification, flat-width washing, drying in a drying cylinder, ANF dispersion spraying, spray protonation reduction, electromagnetic heating roller drying, and winding into a single preparation device. The entire process is connected via conveyor rollers, improving automation and production efficiency. Furthermore, the preparation of lithium-ion battery separators primarily utilizes common equipment from the paper and textile printing and dyeing industries, such as headboxes, conveyor rollers, spraying devices, flat-width washing machines, and electromagnetic heating rollers, for battery separator modification. This approach offers excellent compatibility and scalability with existing lithium-ion battery separator production lines, facilitating large-scale industrial application. It avoids the low efficiency, difficult yield control, and high cost associated with the step-by-step preparation of multilayer composite separators in related technologies, thereby improving preparation efficiency, lithium-ion battery separator yield, and reducing costs.

[0070] The preparation method of the lithium battery separator disclosed herein will be described in detail below with reference to the embodiments.

[0071] Example 1

[0072] Step 1: Mix ethyl acrylate, hydroquinone, and sodium dodecylbenzenesulfonate at a mass ratio of 99:0.5:0.5, dissolve them in ethanol, then dilute to a concentration of 30%, place in the first mixing tank, and transfer to the first headbox via a head pump.

[0073] Step 2: Control the nozzle size of the first headstock to 0.2 mm, the spray pressure to 0.1 MPa, and the spray rate to 0.1 L / min, so that the composite monomer solution is uniformly sprayed onto the PE membrane;

[0074] Step 3: The PE membrane coated with the composite monomer solution is conveyed to the electron beam irradiation equipment through the conveyor roller, and the membrane is modified by electron beam irradiation with 300 KeV energy and 30 kGy dose.

[0075] Step 4: The electron beam irradiated modified diaphragm is conveyed to a flat washing machine for washing via a conveyor roller, and then conveyed to a drying cylinder for drying.

[0076] Step 5: Place the waste para-aramid short fibers with a length of 3 mm into the second mixing tank, add potassium hydroxide and DMSO solution, and stir continuously for 4 h to obtain an ANF / DMSO dispersion with a concentration of 0.5%.

[0077] Step 6: The above dispersion is transferred to the second headbox via a headbox pump. The nozzle size of the second headbox is controlled to be 0.5 mm, the spraying pressure to be 0.1 MPa, and the spraying rate to be 0.2 L / min, so that the ANF / DMSO dispersion sprayed onto the irradiated modified PE membrane is uniform and the thickness is controllable.

[0078] Step 7: The membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by the conveyor roller. The nozzle size of the spraying device is controlled to be 0.1 mm, the spraying pressure is 0.2 MPa, and the spraying rate is 0.02 L / min. The spraying device sprays water on the surface of the membrane, which is protonated and reduced to form ANF hydrogel / modified PE membrane.

[0079] Step 8: The above-mentioned ANF hydrogel / modified PE separator is transferred to an electromagnetic heating roller for drying at a temperature of 40°C. Finally, it is wound up by a winding roller to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0080] The performance of the low-closed-pore, high-temperature resistant lithium battery separator prepared in Example 1 was tested, and the specific parameters are shown in Table 1:

[0081] Table 1

[0082]

[0083] Figure 3 The figure shows the DSC of the low-closed-cell, high-temperature resistant lithium battery separator prepared in Example 1. As can be seen from the figure, its melting point is relatively low, only 118.3℃. Figure 4 The image shows a TEM image of the ANF prepared in Example 1. It can be observed that the prepared ANF has a diameter of only 10-50 nm and an extremely high aspect ratio. Figure 5 This is a physical image of the low-closed-cell, high-temperature resistant lithium battery separator prepared in Example 1. As can be seen, the low-closed-cell, high-temperature resistant lithium battery separator prepared in Example 1 is a light yellow film. Figure 6 The image shows a SEM image of the low-closed-pore, high-temperature resistant lithium battery separator prepared in step 1. It can be observed that the aramid nanofibers on its surface are interwoven and have a nano-sized porous structure. Figure 7 This is a comparison of the thermal shrinkage performance of the low-closed-cell high-temperature resistant lithium battery separator prepared in Example 1 and the base film. After baking at 145°C for 1 h, the thermal shrinkage rate of the base film was 67.3%, while the thermal shrinkage rate of the low-closed-cell high-temperature resistant lithium battery separator prepared in Example 1 was 3.1%, demonstrating excellent thermal stability. Figure 8The wettability comparison between the low-closed-cell high-temperature resistant lithium battery separator prepared in Example 1 and the base film shows that the initial diffusion area of ​​the low-closed-cell high-temperature resistant lithium battery separator prepared in Example 1 is much larger than that of the base film, proving that it has better hydrophilicity and wettability.

[0084] Example 2

[0085] Step 1: Isobutyl acrylate, 2,6-di-tert-butyl-p-cresol, and sodium dodecyl sulfate are mixed evenly in a mass ratio of 96:2.5:1.5 and then dissolved in acetone. The mixture is diluted to a concentration of 60% and placed in the first mixing tank. It is then transferred to the first headbox by a head pump.

[0086] Step 2: Control the nozzle size of the first headstock to 2 mm, the spray pressure to 0.2 MPa, and the spray rate to 0.2 L / min, so that the composite monomer solution is evenly sprayed onto the PE membrane;

[0087] Step 3: The PE diaphragm coated with the composite monomer solution is conveyed to the electron beam irradiation equipment through the conveyor roller, and the diaphragm is modified by electron beam irradiation with an energy of 5000 keV and a dose of 500 kGy.

[0088] Step 4: The electron beam irradiated modified diaphragm is conveyed to a flat washing machine for washing via a conveyor roller, and then conveyed to a drying cylinder for drying.

[0089] Step 5: Place the waste para-aramid short fibers with a length of 5 mm into the second closed stirring tank, add potassium hydroxide and DMSO solution, and stir continuously for 4 h to obtain an ANF / DMSO dispersion with a concentration of 5%.

[0090] Step 6: The above dispersion is transferred to the second headbox via a headbox pump. The nozzle size of the second headbox is controlled to be 2 mm, the spraying pressure to be 0.2 MPa, and the spraying rate to be 0.2 L / min, so that the ANF / DMSO dispersion sprayed onto the irradiated modified PE membrane is uniform and the thickness is controllable.

[0091] Step 7: The membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by the conveyor roller. The nozzle size of the spraying device is controlled to be 1 mm, the spraying pressure is 0.5 MPa, and the spraying rate is 0.1 L / min. The spraying device sprays ethanol on the surface of the membrane to protonate and reduce it, forming an ANF hydrogel / modified PE membrane.

[0092] Step 8: The above-mentioned ANF hydrogel / modified PE separator is transferred to an electromagnetic heating roller for drying at a temperature of 50°C. Finally, it is wound up by a winding roller to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0093] Example 3

[0094] Step 1: Mix lauryl acrylate, hydroquinone, and sodium dodecylbenzenesulfonate evenly at a mass ratio of 99:0.5:0.5, dissolve in water, dilute to a concentration of 10%, place in the first mixing tank, and transfer to the first headbox by a head pump;

[0095] Step 2: Control the nozzle size of the first headstock to 0.1 mm, the spray pressure to 0.01 MPa, and the spray rate to 0.01 L / min, so that the composite monomer solution is uniformly sprayed onto the PE membrane.

[0096] Step 3: The PE membrane coated with the composite monomer solution is conveyed to the electron beam irradiation equipment through the conveyor roller, and the membrane is modified by electron beam irradiation with 50 KeV energy and 10 kGy dose.

[0097] Step 4: The electron beam irradiated modified diaphragm is conveyed to a flat washing machine for washing via a conveyor roller, and then conveyed to a drying cylinder for drying.

[0098] Step 5: Place the waste para-aramid short fibers with a length of 1 mm into the second mixing tank, add potassium hydroxide and DMSO solution, and stir continuously for 4 h to obtain an ANF / DMSO dispersion with a concentration of 0.1%.

[0099] Step 6: The above dispersion is transferred to the second headbox via a headbox pump. The nozzle size of the second headbox is controlled to be 0.1 mm, the spraying pressure to be 0.01 MPa, and the spraying rate to be 0.01 L / min, so that the ANF / DMSO dispersion sprayed onto the irradiated modified PE membrane is uniform and the thickness is controllable.

[0100] Step 7: The membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by the conveyor roller. The nozzle size of the spraying device is controlled to be 0.1 mm, the spraying pressure is 0.01 MPa, and the spraying rate is 0.01 L / min. The spraying device sprays ethanol on the surface of the membrane to protonate and reduce it, forming an ANF hydrogel / modified PE membrane.

[0101] Step 8: The above-mentioned ANF hydrogel / modified PE separator is transferred to an electromagnetic heating roller for drying at a temperature of 30°C. Finally, it is wound up by a winding roller to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0102] In this embodiment, by controlling the nozzle size and spray volume of the first headbox, the composite monomer solution can be uniformly sprayed onto the PE diaphragm; electron beam irradiation is used to modify the PE diaphragm, grafting ester monomers onto its surface, ensuring that its thickness and air permeability remain unchanged while significantly reducing the diaphragm's closed-cell temperature; the multi-tank countercurrent design of the flat-width washing machine saves water and chemicals, and can efficiently remove impurities, greatly improving production efficiency; by using waste aramid fibers, the production cost of the diaphragm is reduced; by controlling the nozzle size and spray volume of the second headbox, the ANF / DMSO solution sprayed onto the diaphragm surface is ensured to be continuous and uniform; the spraying device allows for direct protonation reduction, eliminating the solvent exchange step; by controlling the temperature of the electromagnetic heating roller, the diaphragm can be dried without shrinkage.

[0103] The preparation method of this low-closed-pore high-temperature resistant lithium battery separator enables it to quickly soften, melt, and effectively seal the micropore channels when the internal temperature of the battery rises abnormally to a level significantly lower than the melting point of traditional polyolefins (low temperature), thus cutting off the ion flow in time and playing an "early melting" protection function. At the same time, it maintains excellent dimensional stability and mechanical strength under extreme high temperature conditions (>200℃), effectively resisting high-temperature thermal shrinkage and melt fracture, and providing a solid physical isolation barrier for the battery.

[0104] Comparative Example

[0105] Step 1: Dilute anhydrous ethanol to a concentration of 30%, place it in the first mixing tank, and transfer it to the first headbox using a headbox pump;

[0106] Step 2: Control the size of the nozzle in the first headstock to 0.2 mm, the spray pressure to 0.1 MPa, and the spray rate to 0.1 L / min, so that the composite monomer solution is uniformly sprayed onto the PE membrane.

[0107] Step 3: The PE membrane coated with the composite monomer solution is conveyed to the irradiation equipment through the conveyor roller, and the membrane is modified by electron beam irradiation with 300 keV energy and 30 kGy dose.

[0108] Step 4: The electron beam irradiated modified separator is conveyed to a flat washing machine for washing via a conveyor roller, and then conveyed to a drying cylinder for drying. The separator is then wound up to obtain a low-closed-cell, high-temperature resistant lithium battery separator.

[0109] The membranes prepared in the comparative proportions were subjected to performance testing, and the results are shown in Table 2.

[0110] Table 2

[0111]

[0112] Figure 9This is a physical image of a lithium battery separator prepared in proportion, showing that it appears as a white thin film. Figure 10 The comparison shows the thermal shrinkage performance of the lithium battery separator and the base film prepared in the comparative example. After baking at 145℃ for 1 h, the thermal shrinkage rate of the base film was 67.3%, while the thermal shrinkage rate of the lithium battery separator prepared in the comparative example was 56.4%, showing no significant improvement compared to the base film. Figure 11 The comparison shows the wettability of the lithium battery separator prepared in the comparative proportion and the base film. It can be observed that the lithium battery separator prepared in the comparative proportion does not show significant improvement compared with the base film.

[0113] This disclosure provides a complete continuous roll-to-roll production process that efficiently integrates key steps such as ester monomer solution spraying, electron beam irradiation modification, flat-width washing, drying in a drying cylinder, ANF dispersion spraying, spray protonation reduction, electromagnetic heating roller drying, and winding. The entire process is connected by conveyor rollers, achieving a high degree of automation and significantly improving production efficiency. Furthermore, the process primarily utilizes equipment commonly used in the paper and textile printing and dyeing industries, such as headboxes, conveyor rollers, spraying devices, flat-width washing machines, and electromagnetic heating rollers. Drawing on papermaking production technology, this method is applied to battery separator modification, exhibiting good compatibility and scalability with existing lithium-ion battery separator production lines. This facilitates large-scale industrial production and application, avoiding the problems of low efficiency, difficult yield control, and high cost associated with traditional step-by-step preparation of multilayer composite separators.

[0114] This disclosure also provides a low-closed-cell, high-temperature resistant lithium battery separator prepared according to steps S110 to S180. This low-closed-cell, high-temperature resistant lithium battery separator can be applied to lithium batteries. The low-closed-cell, high-temperature resistant lithium battery separator prepared in this disclosure can rapidly soften and melt, effectively sealing micropore channels and promptly cutting off ion flow when the internal temperature of the battery abnormally rises to a level significantly lower than the melting point of traditional polyolefins (low temperature), thus providing an "early melting" protection function. Simultaneously, it maintains excellent dimensional stability and mechanical strength under extreme high-temperature conditions (>200°C), effectively resisting high-temperature thermal shrinkage and melt fracture, providing a robust physical isolation barrier for the battery.

[0115] This disclosure also provides an apparatus for preparing a low-closed-cell, high-temperature resistant lithium battery separator. This apparatus is used to prepare the low-closed-cell, high-temperature resistant lithium battery separator using the aforementioned method. The apparatus includes: a first mixing tank, a headstock pump, a first headbox, a nozzle, an electron beam irradiation device, a flat-web washing machine, a drying cylinder, a second mixing tank, a second headbox, a conveyor roller, a spraying device, an electromagnetic heating roller, and a winding roller. This apparatus can automatically achieve continuous, large-scale production of low-closed-cell, high-temperature resistant lithium battery separators, avoiding the costs and time-consuming nature of manual labor, improving production efficiency, reducing costs, and thus meeting practical application needs.

[0116] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this disclosure and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0117] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

[0118] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method for preparing a low-closed-pore, high-temperature resistant lithium battery separator, characterized in that, include: After the ester monomer, polymerization inhibitor and surfactant are mixed evenly, they are dissolved in a polar solvent and diluted in proportion to obtain a composite monomer solution. The composite monomer solution is placed in the first stirring tank and transferred to the first headbox by the headbox pump. Control the nozzle size and spray pressure of the first headstock box to ensure that the composite monomer solution is evenly sprayed onto the PE membrane; A PE diaphragm coated with a composite monomer solution is conveyed to an electron beam irradiation device via a conveyor roller. The electron beam irradiation device is used to modify the PE diaphragm coated with the composite monomer solution by electron beam irradiation to obtain an electron beam irradiated modified PE diaphragm. The electron beam irradiated modified PE diaphragm is washed with water using a flat-width washing machine and then transferred to a drying cylinder for drying. Aramid short-cut fibers were placed in a second mixing tank, and potassium hydroxide and DMSO solutions were added and continuously stirred to obtain an ANF / DMSO dispersion. The ANF / DMSO dispersion is fed into the second headbox, and the nozzle size of the second headbox is controlled to spray the electron beam irradiated modified PE membrane to obtain a membrane sprayed with the ANF / DMSO dispersion. The membrane coated with ANF / DMSO dispersion is conveyed to the spraying device by the conveyor roller, so that the membrane coated with ANF / DMSO dispersion is protonated and reduced to form ANF hydrogel / modified PE membrane. The ANF hydrogel / modified PE separator is conveyed to an electromagnetic heating roller for drying and then wound up to obtain the low-closed-cell, high-temperature resistant lithium battery separator.

2. The method according to claim 1, characterized in that, The mass ratio of the ester monomer, polymerization inhibitor, and surfactant is (96~99):(2.5~0.5):(1.5~0.5), and the concentration of the composite monomer solution is 10%~60%.

3. The method according to claim 1, characterized in that, The ester monomer is one or more of ethyl acrylate, isooctyl acrylate, lauryl methacrylate, isobutyl acrylate, and lauryl acrylate; the polymerization inhibitor is one or more of 2,6-di-tert-butyl-p-cresol, hydroquinone, and p-benzoquinone; the surfactant is one or a mixture of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and polyglycerol-10 oleate; and the polar solvent is one or more of acetone, ethanol, or water.

4. The method according to claim 1, characterized in that, The first headbox has a nozzle size of 0.1~2 mm, a spray pressure of 0.01~0.2 MPa, and a spray rate of 0.01~0.2 L / min. The second headbox has a nozzle size of 0.1~2 mm, a spray pressure of 0.01~0.2 MPa, and a spray rate of 0.01~0.2 L / min.

5. The method according to claim 1, characterized in that, The energy of the electron beam irradiation is 50~5000 keV, and the irradiation dose is 10~500 kGy.

6. The method according to claim 1, characterized in that, The length of the aramid chopped fibers is 1~5 mm, and the concentration of the ANF / DMSO dispersion is 0.1%~5%.

7. The method according to claim 1, characterized in that, The nozzle size of the spraying device is 0.1~1 mm, the spraying pressure is 0.01~0.5 MPa, and the spraying rate is 0.01~0.1 L / min.

8. The method according to claim 4, characterized in that, The temperature of the electromagnetic heating roller is 30~50℃.

9. A low-closed-pore, high-temperature resistant lithium battery separator, characterized in that, The low-closed-cell, high-temperature resistant lithium battery separator is prepared by the method described in any one of claims 1-8.

10. An apparatus for preparing a low-closed-pore, high-temperature resistant lithium battery separator, characterized in that, The apparatus for preparing the low-closed-cell, high-temperature resistant lithium battery separator is used to prepare the low-closed-cell, high-temperature resistant lithium battery separator by the method for preparing the low-closed-cell, high-temperature resistant lithium battery separator according to any one of claims 1-8; the apparatus for preparing the low-closed-cell, high-temperature resistant lithium battery separator includes: a first mixing tank, a headstock pump, a first headbox, a nozzle, an electron beam irradiation device, a flat-width washing machine, a drying cylinder, a second mixing tank, a second headbox, a conveying roller, a spraying device, an electromagnetic heating roller, and a winding roller.

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