Modified composite separation membrane and method for manufacturing the same
Patent Information
- Authority / Receiving Office
- KR · KR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-10-20
- Publication Date
- 2026-08-12
Smart Images
Figure 112024048660509-PCT00019_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to the technical field of battery separators, and in particular to a modified composite separator and a method for manufacturing the same. Background Technology
[0002] Lithium-ion batteries are a new type of eco-friendly rechargeable battery that was successfully developed and commercialized in 1990. Compared to traditional lead-acid and cadmium-nickel batteries, lithium-ion batteries offer advantages such as high energy density, high operating voltage, long cycle life, small size, no memory effect, fast charging and discharging, and environmental protection. Lithium-ion batteries are widely used in 3C products such as mobile phones, laptops, and power tools, and have established themselves as the main direction of development for rechargeable batteries at the current stage. In recent years, with the implementation of new energy strategies worldwide, high-energy-density lithium-ion batteries have been developed even more rapidly. Energy density has improved to the 300 Wh / kg level, and application fields have rapidly expanded from traditional small 3C electronics to large power equipment sectors, including new energy electric vehicles, energy storage systems, large unmanned aerial vehicles, ships, and pure electric aircraft. Due to the rapid development of 3C products, large power equipment, and especially new energy electric vehicles, requirements regarding the specific capacity and safety of lithium-ion batteries have also increased.
[0003] Lithium-ion batteries are primarily composed of positive electrode materials, negative electrode materials, electrolytes, and separators. The separator is a critical component that separates the positive and negative electrodes to prevent short circuits and allows lithium ions to pass freely. The separator plays a vital role in improving the overall performance of the battery and is known in the battery industry as the battery's "third electrode." Although the separator does not participate in the battery reaction, its structure and performance have a significant impact on the battery's manufacturing, performance, lifespan, reliability, and safety. Conventional lithium-ion battery separators generally utilize polyolefin materials, represented by polyethylene and polypropylene. These are manufactured through wet, dry single-stretch, dry double-stretch, and other processes and possess excellent tensile properties and pore size distribution. Currently, conventional polyolefin microporous separators are widely used for lithium-ion batteries due to their excellent chemical stability, thickness, and mechanical strength. However, these separators experience severe thermal shrinkage at higher temperatures. These issues are critical to battery safety, as contact between the positive and negative electrodes inside the battery can cause a short circuit, potentially leading to fire or explosion. Furthermore, the polarity of the separator is completely different from that of the electrolyte. Since the separator is a non-polar material and the electrolyte is polar, it is difficult for the separator to wet the electrolyte, resulting in poor wettability. Insufficient wettability and low porosity of the separator significantly reduce the conductivity of lithium ions, ultimately affecting the overall performance of the lithium-ion battery. These problems with polyolefin-based separators are a critical obstacle to the development of safe, high-output lithium-ion batteries.
[0004] Therefore, the development of new separator materials with high heat resistance and excellent wettability is a key challenge that the lithium battery industry urgently needs to address, and is becoming one of the most important research directions, especially for the development of high-capacity, high-energy-density lithium-ion batteries.
[0005] Considering the above situation, current modification methods mainly include mixed modification, composite modification, coating modification, ion modification, and other modification methods. Surface coating is one of the most important and commonly used methods. The surface of polyolefin membranes is generally coated with ceramic coating materials such as aluminum oxide (Al2O3), silicon dioxide (SiO2), and titanium dioxide (TiO2). Coatings can significantly improve the wettability of the membrane due to the membrane's electrolyte and heat resistance. However, polyolefin membranes coated and modified with ceramics continue to face several problems. For example, inorganic ceramics have low compatibility with the substrate, and the ceramic coating is prone to peeling off. Furthermore, the density of the ceramic layer adds weight, and the reduced insulation of the ceramic leads to insufficient dielectric properties, especially when the base membrane thins or melts. Another problem is that inorganic coatings cannot form a continuous, self-supporting structure on their own because they consist of a powder aggregate structure. Therefore, inorganic coatings generally exhibit problems such as easy powder loss and peeling during use. More importantly, the inorganic particle layer of inorganic-coated separators typically pulverizes and breaks down at high temperatures, leading to separator failure. Consequently, the occurrence of thermal runaway cannot be suppressed, and the requirements for high heat resistance and high thermal dimensional stability of lithium-ion battery separators cannot be met.
[0006] Considering the aforementioned problems, research utilizing high-temperature resistant polymers as coating materials is increasing, and commonly used polymers include PVDF, PMMA, and PEI. For example, Patent CN104993089 reports an aramid-coated lithium-ion battery separator and a method for manufacturing the same. According to the patent, the method involves obtaining an aramid slurry by uniformly mixing an aramid solution, an emulsifier solution, and a binder, and then coating the resulting polymer colloidal fluid onto the surface of a polyolefin separator. The thermal dimensional stability of the separator is improved to some extent, thereby enhancing the safety and reliability of the lithium-ion battery. However, the organic polymer used in this method lacks heat resistance, and the improvement in thermal dimensional stability is insufficient.
[0007] Considering the aforementioned drawbacks, existing coatings are innovated and new coating technologies are developed to solve the problem of inorganic particle coatings breaking and pulverizing at high temperatures. By improving the heat resistance of the separator and preparing a new separator material equipped with heat resistance and high thermal dimensional stability, the urgent demands of high-energy density lithium-ion batteries for high-temperature resistant separators and high safety are met.
[0008] The present invention provides a modified composite separator, wherein the coated and modified composite separator comprises a base membrane and a coating layer, wherein the coating layer is coated on one or both sides of the base membrane and the coating layer comprises at least two types of three components: high temperature resistant polymer microspheres, high temperature resistant polymer nanofibers, and inorganic particles. When a high temperature resistant polymer is added to the coating layer, the separator exhibits excellent thermal protection and high temperature thermal dimensional stability because the polymer is an organic material that is more closely bonded with binders, etc. At the same time, the high temperature resistant polymer has a low density, can increase the liquid retention rate of the separator, and can improve the cycle performance and heat resistance of the battery.
[0009] The base film is a polymer base film or a polymer base film coated with inorganic particles. The particle size of the high-temperature resistant polymer microspheres is 3 to 20,000 nm, preferably 5 to 18,000 nm, more preferably 8 to 15,000 nm; more preferably, the particle size of the high-temperature resistant polymer microspheres is 3 to 5,000 nm, preferably 5 to 3,000 nm, more preferably 8 to 2,000 nm. The diameter of the high-temperature resistant polymer nanofibers is 5 to 1,500 nm, preferably 6 to 1,450 nm, more preferably 8 to 1,350 nm. The length of the high-temperature resistant polymer nanofibers is 0.5 to 1,000 μm, preferably 0.6 to 950 μm, more preferably 1.0 to 900 μm. The thickness of the base film is 1.5 to 40 μm, preferably 2.0 to 35 μm, more preferably 3.5 to 30 μm. The thickness of the coating layer is 0.2 to 10 μm, preferably 0.3 to 9 μm, more preferably 0.5 to 8 μm. The total thickness of the modified composite membrane is 2.0 to 45 μm, preferably 2.5 to 40 μm, most preferably 3 to 36 μm.
[0010] The present invention also provides a method for manufacturing a coated and modified composite separation membrane comprising the following steps:
[0011] (1) A step of formulating a coating slurry comprising two or more of the following:
[0012] High temperature resistant polymer microspheres,
[0013] High temperature resistant polymer nanofibers, and
[0014] Inorganic particles;
[0015] (2) A step of coating the above coating slurry on one or both sides of a base film.
[0016] In one aspect, the present invention also provides a coating slurry comprising a slurry solvent and at least two of the following: high-temperature resistant polymer microspheres, high-temperature resistant polymer nanofibers, and inorganic particles. The coating slurry is used to manufacture a coated and modified composite separation membrane through a coating method.
[0017] In one aspect, the present invention also provides a lithium-ion battery characterized by comprising a positive electrode, a negative electrode, an electrolyte, and a coated and modified composite separator.
[0018] The coated and modified composite membrane of the present invention and the method for manufacturing the same have one, more than, or all of the following beneficial effects.
[0019] The present invention provides a composite separator coated with a high-temperature resistant polymer and modified, wherein the coating layer of the modified composite separator comprises high-temperature resistant polymer microspheres, high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers, or high-temperature resistant polymer microspheres or high-temperature resistant polymer nanofibers and inorganic particles. The high-temperature resistant polymer has good adhesion to binders, etc., providing an excellent thermal protection effect to the separator, and can significantly improve the heat resistance of the separator and the safety of the battery.
[0020] The density of high-temperature resistant polymers is significantly lower than that of inorganic particles, which is advantageous for greatly reducing the weight of the coating and the weight per unit area of the separator, and for increasing the energy density of the battery.
[0021] The modified composite separator manufactured in the present invention can improve the speed performance and cycle life of a battery because both the high-temperature resistant polymer and the electrolyte are organic materials having polar structures, resulting in high electrolyte absorption and liquid retention rates.
[0022] The coating technology provided by the present invention can be applied to any substrate separator to achieve coating formation and has a wide range of applications. The molding process is simple and can be carried out through any one of electrostatic spraying, blade coating, extrusion coating, transfer coating, dip coating, wire rod coating, gravure, or micro-gravure coating, making it easy to implement on an industrial scale and offering excellent prospects for industrialization.
[0023] The present invention manufactures a high-temperature resistant polymer having a fiber / microsphere composite form using a template method, spray drying technology, electrospinning technology, blowing spinning technology, or blowing-assisted electrospinning. The preparation process is simple and efficient.
[0024] The integration of high-temperature resistant polymer nanofibers forms a network structure, enhances the integrity of the coating, and can avoid the problem of pure microsphere structures being crushed due to binder breakdown at high temperatures.
[0025] High-temperature resistant polymers can improve the thermal stability of polyolefin separators. Furthermore, at high temperatures, polyolefins undergo thermal melting to effectively achieve thermal sealing and thermal pore closure, significantly enhancing battery safety.
[0026] When the coating of a modified composite separator is formed by mixing high-temperature resistant polymer nanofibers and inorganic particles, a "reinforced concrete" structure is formed after mixing the high-temperature resistant polymer nanofibers and ceramics. Since the nanofibers form a network, the mixed coating possesses continuous self-supporting properties, allowing the inorganic coating to maintain good integrity without breakage or pulverization even when the base membrane melts at high temperatures, thereby exhibiting excellent thermal insulation. By solving the problem of pure inorganic particle coatings pulverizing or breaking at high temperatures, the heat resistance of the separator and battery safety can be significantly improved.
[0027] When high-temperature resistant polymer nanofibers are applied to a modified composite separator, high-temperature thermal dimensional stability is significantly improved. Furthermore, the incorporation of high-temperature resistant polymer nanofibers greatly enhances the overall strength of the mixed coating. Simultaneously, because the density of the high-temperature resistant polymer nanofibers is significantly lower than that of inorganic particles, the weight of the coating and the separator per unit area are greatly reduced. The modified composite separator possesses the characteristic of being lightweight, which contributes to improving the energy density of the battery.
[0028] When high-temperature resistant polymer nanofibers are present in a modified composite separator, the electrolyte absorption rate and electrolyte retention rate of the separator are increased because the high-temperature resistant polymer nanofibers form a network structure in the mixed coating, which can improve the speed performance and cycle life of the battery. Brief explanation of the drawing
[0029] Figure 1 is a scanning electron microscope image at 5000x magnification of a polyimide having a fiber / microsphere composite form prepared according to Example 1.1. Figure 2 is a scanning electron microscope image at 2000x magnification of a polyimide-coated modified polyolefin composite separator prepared according to Example 1.1. Figure 3 is a scanning electron microscope image at 5000x magnification of a polyimide having a fiber / microsphere composite form prepared according to Example 1.2. Figure 4 is a scanning electron microscope image at 2000x magnification of a polyimide-coated modified polyolefin composite separator prepared according to Example 1.2. Figure 5 is a scanning electron microscope image at 5,000x magnification of a polyimide having a fiber / microsphere composite form prepared according to Example 1.3. Figure 6 is a scanning electron microscope image at 2000x magnification of a polyimide-coated modified polyolefin composite separator prepared according to Example 1.3. Figure 7 is a photograph comparing the thermal shrinkage rates at different temperatures of a polyolefin composite separator modified by coating polyimide prepared according to Example 1.3. Figure 8 is a scanning electron microscope image of the 7+4CP+4CP modified composite membrane provided in Example 2.1 of the present invention. Figure 9 is a scanning electron microscope image of the 7+4C+4C modified composite membrane provided in Example 2.1 of the present invention. FIG. 10 is a scanning electron microscope image of the modified composite membrane provided in Example 2.15 of the present invention. Figure 11 is a scanning electron microscope image of the modified composite separation membrane provided in Example 3.1 of the present invention. FIG. 12 is a scanning electron microscope image of the modified composite membrane provided in Example 3.2 of the present invention. FIG. 13 is a scanning electron microscope image of the modified composite membrane provided in Example 3.3 of the present invention. FIG. 14 is a scanning electron microscope image of the modified composite membrane provided in Example 3.4 of the present invention. FIG. 15 is a scanning electron microscope image of the modified composite membrane provided in Example 3.5 of the present invention. FIG. 16 is a scanning electron microscope image of the modified composite membrane provided in Example 4.1 of the present invention. Specific details for implementing the invention
[0030] Specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are used only to illustrate and explain the present invention and are not intended to limit the present invention.
[0031] 1. As a coated and modified composite separation membrane,
[0032] The above-mentioned coated and modified composite separation membrane comprises a base membrane and a coating layer, and
[0033] The above coating layer is coated on any one or both sides of the base film, and
[0034] The coating layer comprises at least two of the following:
[0035] b2.1 High temperature resistant polymer microsphere,
[0036] b2.2 High-temperature resistant polymer nanofibers, and
[0037] b2.3 inorganic particles.
[0038] 2. A coated and modified composite separation membrane, characterized in that, in the first embodiment, the high-temperature resistant polymer comprises polyimide.
[0039] 3. A coated and modified composite separator, characterized in that, in the first embodiment, the particle size of the high-temperature resistant polymer microsphere is 3 to 20,000 nm, preferably 5 to 18,000 nm, more preferably 8 to 15,000 nm; and more preferably, the particle size of the high-temperature resistant polymer microsphere is 3 to 5,000 nm, preferably 5 to 3,000 nm, and more preferably 8 to 2,000 nm.
[0040] 4. A coated and modified composite separation membrane, characterized in that, in the first embodiment, the thickness of the base membrane is 1.5 to 40 μm, preferably 2.0 to 35 μm, and more preferably 3.5 to 30 μm.
[0041] 5. A coated and modified composite membrane, characterized in that, in the first embodiment, the total thickness of the modified composite membrane is 2.0 to 45 μm, preferably 2.5 to 40 μm, and most preferably 3 to 36 μm.
[0042] 6. A coated and modified composite separation membrane, characterized in that, in the first embodiment, the thickness of the coating layer is 0.2 to 10 μm, preferably 0.3 to 9 μm, and more preferably 0.5 to 8 μm.
[0043] 7. A coated and modified composite separation membrane, characterized in that, in the first or second embodiment, the base membrane is a polyolefin base membrane or a polyolefin base membrane coated with inorganic particles.
[0044] 8. A coated and modified composite separation membrane, characterized in that, in the second embodiment, the coating layer comprises polyimide nanofibers / polyimide microspheres.
[0045] 9. A coated and modified composite separation membrane, characterized in that, in the seventh embodiment, the thickness of the polyolefin base membrane coated with the inorganic particles is 3 to 40 μm.
[0046] 10. A coated and modified composite separation membrane, characterized in that, in the eighth embodiment, the diameter of the polyimide nanofibers in the polyimide coating layer is 20 to 1000 nm.
[0047] 11. A coated and modified composite separation membrane, characterized in that, in the first embodiment, the coating layer comprises high-temperature resistant polymer microspheres and inorganic particles, and the weight ratio of the high-temperature resistant polymer microspheres to the inorganic particles is 0.1 to 100:99.9 to 0, preferably 0.1 to 99.9:99.9 to 0.1.
[0048] 12. A coated and modified composite separation membrane, characterized in that, in the 11th embodiment, the weight ratio of high-temperature resistant polymer microspheres to inorganic particles in the coating layer is 1 to 100:99 to 0, preferably 5 to 100:95 to 0, most preferably 30 to 100:70 to 0, and more preferably, the weight ratio of high-temperature resistant polymer microspheres to inorganic particles in the coating layer is 1 to 99.9:99 to 0.1, preferably 5 to 99.9:95 to 0.1, most preferably 30 to 99.9:70 to 0.1.
[0049] 13. In the 11th embodiment, the base film is at least one of a polymer base film and a base film coated with inorganic particles;
[0050] Preferably, the polymer base membrane comprises at least one of a polyolefin base membrane, a cellulose base membrane, a polyester base membrane, an aramid base membrane, a polyimide base membrane, and an organic-inorganic hybrid base membrane, forming a coated and modified composite separation membrane.
[0051] 14. A coated and modified composite separation membrane, wherein, in the 13th embodiment, the polymer base membrane comprises a monolayer, a double layer, or a multilayer, and the polymer base membranes included in each layer are the same or different.
[0052] 15. A coated and modified composite separation membrane, wherein in any one of the 11th to 14th embodiments, the high-temperature resistant polymer microsphere comprises at least one of an unmodified high-temperature resistant polymer microsphere, a surface-modified high-temperature resistant polymer microsphere, and an inorganic hybrid high-temperature resistant polymer microsphere.
[0053] 16. A coated and modified composite separation membrane in the 15th embodiment, wherein the polymer of the unmodified high-temperature resistant polymer microsphere, the surface-modified high-temperature resistant polymer microsphere, and the inorganic hybrid high-temperature resistant polymer microsphere comprises at least one of P84, polyetherimide, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylidene fluoride, polyvinylidene fluoride copolymer, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polytetrafluoroethylene, polyimide, polyester, cellulose, polyetheretherketone, polyaryl ether, polyamide, and polybenzimidazole.
[0054] 17. A coated and modified composite separation membrane, wherein, in the 16th embodiment, the surface-modified high-temperature resistant polymer microsphere comprises at least one of an inorganic surface-modified high-temperature resistant polymer microsphere, a high-temperature resistant polymer microsphere having a polar group after surface treatment, or a high-temperature resistant polymer microsphere surface-coated with a functionalized polymer layer containing a polar group.
[0055] 18. A coated and modified composite separation membrane, wherein, in the 15th embodiment, the inorganic hybrid high-temperature resistant polymer microsphere comprises at least one of polyimide / silica microspheres, polyimide / titanium dioxide microspheres, polyimide / zirconia microspheres, polyimide / zinc oxide microspheres, polyimide / magnesium oxide microspheres, polyimide / magnesium hydroxide microspheres, and polyimide / boemite microspheres.
[0056] 19. In any one of the 10th to 13th embodiments, the inorganic particles in the coating layer comprise at least one of ceramic, metal oxide, metal hydroxide, metal carbonate, silicate, kaolin, talc, mineral, and glass; preferably, at least one of boehmite, alumina, silica, barium titanate, titanium dioxide, zinc oxide, magnesium oxide, magnesium hydroxide, zirconia, or oxide solid electrolyte;
[0057] Preferably, the oxide solid electrolyte comprises at least one of a perovskite type, NASICON type, LISICON type, garnet type, and LiPON type electrolyte;
[0058] A coated and modified composite separation membrane, characterized in that, preferably, the average particle size of the inorganic particles is 3 nm to 5 μm, preferably 7 nm to 4.9 μm, and most preferably 10 nm to 4.5 μm.
[0059] 20. In the 11th to 14th embodiments, the coating layer further comprises at least one of a binder, a surfactant, a dispersant, a wetting agent, and an antifoaming agent;
[0060] A coated and modified composite separation membrane characterized by the amount of binder being 0.3 to 10.5 parts by weight; the amount of surfactant being 0.05 to 7 parts by weight; the amount of dispersant being 0.05 to 9 parts by weight; the amount of wetting agent being 0.02 to 7 parts by weight; and the amount of defoaming agent being 0.04 to 4 parts by weight.
[0061] 21. A coated and modified composite separation membrane, characterized in that, in the first embodiment, the coating layer comprises high-temperature resistant polymer nanofibers and inorganic particles, and the weight ratio of the high-temperature resistant polymer nanofibers to the inorganic particles is (0.4 to 65):(99.6 to 35).
[0062] 22. A coated and modified composite separation membrane in the 21st embodiment, wherein the weight ratio of high-temperature resistant polymer nanofibers to inorganic particles in the coating layer is (1 to 64):(99 to 36), preferably (3 to 62):(97 to 38), most preferably (5 to 59):(95 to 41).
[0063] 23. In the 21st or 22nd embodiment, the base film is at least one of a polymer base film and a base film coated with inorganic particles;
[0064] Preferably, the polymer base membrane comprises at least one of a polyolefin base membrane, a cellulose base membrane, a polyester base membrane, and an aramid base membrane, a coated and modified composite separation membrane.
[0065] 24. A coated and modified composite separation membrane, wherein in any one of the 21st to 23rd embodiments, the polymer base membrane comprises a single layer, a double layer, or a multilayer, and the polymer base membrane included in each layer is the same or different.
[0066] 25. A coated and modified composite separation membrane, characterized in that, in any one of the 21st to 24th embodiments, the high-temperature resistant polymer nanofiber comprises at least one of an unmodified high-temperature resistant polymer nanofiber, a surface-modified high-temperature resistant polymer nanofiber, and an inorganic hybrid high-temperature resistant polymer nanofiber.
[0067] 26. In any one of the 21st to 25th embodiments, the diameter of the high-temperature resistant polymer nanofiber is 5 to 1500 nm, preferably 6 to 1450 nm, more preferably 8 to 1350 nm, and / or,
[0068] A coated and modified composite separation membrane, wherein the length of the high-temperature resistant polymer nanofiber is 0.5 to 1000 μm, preferably 0.6 to 950 μm, more preferably 1.0 to 900 μm.
[0069] 27. A coated and modified composite separation membrane, wherein in any one of the 21st to 26th embodiments, the unmodified high-temperature resistant polymer nanofiber and the high-temperature resistant polymer nanofiber used for surface modification and inorganic hybridization comprise at least one of P84 nanofiber, polyetherimide nanofiber, polyvinylidene fluoride and its copolymer nanofiber, polyvinylidene fluoride-hexafluoropropylene nanofiber, polytetrafluoroethylene nanofiber, polyphosphazene nanofiber, polyacrylonitrile nanofiber, polyimide nanofiber, polyester nanofiber, cellulose nanofiber, polyetheretherketone nanofiber, polyarylether nanofiber, polyamide nanofiber, and polybenzimidazole nanofiber.
[0070] 28. A coated and modified composite separation membrane, wherein, in any one of the 21st to 27th embodiments, the surface-modified high-temperature resistant polymer nanofiber comprises at least one of an inorganic surface-modified high-temperature resistant polymer nanofiber, a high-temperature resistant polymer nanofiber having polar groups after surface treatment, or a high-temperature resistant polymer nanofiber surface-coated with a functionalized polymer layer containing polar groups.
[0071] 29. In any one of the 21st to 28th embodiments, the inorganic particles in the coating layer comprise at least one of ceramic, metal oxide, metal hydroxide, metal carbonate, silicate, kaolin, talc, mineral, and glass; preferably, at least one of boehmite, alumina, silica, barium titanate, titanium dioxide, zinc oxide, magnesium oxide, magnesium hydroxide, zirconia, or oxide solid electrolyte;
[0072] Preferably, the oxide solid electrolyte comprises at least one of a perovskite type, NASICON type, LISICON type, garnet type, and LiPON type electrolyte;
[0073] A coated and modified composite separation membrane characterized in that, preferably, the average particle size of the inorganic particles is 10 nm to 5 μm, preferably 11 nm to 4.9 μm, and most preferably 15 nm to 4.5 μm.
[0074] 30. A coated and modified composite separation membrane, wherein in any one of the 21st to 29th embodiments, the coating layer further comprises at least one of a binder, a surfactant, a dispersant, a wetting agent, and an antifoaming agent.
[0075] 31. In any one of the 21st to 29th embodiments, the amount of the binder is 0.5 to 12.5 parts by weight, preferably 0.6 to 12 parts by weight, more preferably 1.0 to 9 parts by weight, and / or,
[0076] The amount of surfactant is 0.1 to 5 parts by weight, preferably 0.2 to 4.9 parts by weight, more preferably 0.4 to 4.7 parts by weight, and / or,
[0077] The amount of dispersant is 0.1 to 7 parts by weight, preferably 0.2 to 6.9 parts by weight, more preferably 0.4 to 6.4 parts by weight, and / or,
[0078] The amount of wetting agent is 0.05 to 5 parts by weight, preferably 0.06 to 4.9 parts by weight, more preferably 0.09 to 4.7 parts by weight, and / or,
[0079] A coated and modified composite separation membrane, wherein the amount of a defoaming agent is 0.1 to 4 parts by weight, preferably 0.2 to 3.9 parts by weight, more preferably 0.4 to 3.5 parts by weight.
[0080] 32. A method for manufacturing a coated and modified composite separation membrane as described in any one of the 21st to 30th embodiments, wherein the method comprises:
[0081] (1) A step of formulating a coating slurry comprising two or more of the following:
[0082] b2.1 High-temperature resistant polymer microspheres,
[0083] b2.2 High-temperature resistant polymer nanofibers, and
[0084] b2.3 Inorganic particles;
[0085] (2) A manufacturing method comprising the step of coating the above coating slurry on one or both sides of a base film.
[0086] 33. In the 32nd embodiment, the coating slurry comprises high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers, wherein the high-temperature resistant polymer is polyimide, and the method comprises the following steps:
[0087] A: A step of preparing a polyamic acid solution by low-temperature condensation polymerization in a polar aprotic solvent with an intrinsic viscosity controlled to 0.01 to 1 dl / g using a dianhydride and a diamine as monomers; a step of preparing a polyamic acid material having a nanofiber / microsphere composite form by using a template method, spray drying technology, electrospinning technology, blowing spinning technology, or blowing-assisted electrospinning, and adjusting spinning parameters as necessary;
[0088] B: A step of thermally imidizing the polyamic acid material manufactured in Step A by high-temperature heat treatment to produce a polyimide material;
[0089] C: Step of formulating a coating slurry: A step of dispersing the polyimide material prepared in Step B into a dispersion, for example, by dispersing it into the dispersion using ultrasound and then stirring it uniformly, for example, by dispersing it uniformly in a homogenizer; a step of adding a binder, such as a polymer binder, to the polyimide dispersion and stirring it uniformly, for example, by stirring it uniformly in a homogenizer at a stirring speed of 500 to 30,000 rpm;
[0090] D: A step of uniformly applying the coating slurry obtained in step C to the surface of the base film;
[0091] E: A step of drying the composite membrane obtained through the treatment of step D, wherein the drying temperature is 50 to 100°C and the drying time is 0.1 minutes to 12 hours, or 2 minutes to 12 hours.
[0092] 34. In the 33rd embodiment, for the polyamic acid solution used in step A, the dianhydride is one or a mixture of two or more of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (α-BPDA), 4,4'-diphenyl ether dianhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), hexafluorodianhydride (6FDA), bisphenol A diether anhydride (BPADA), and 3,3,4,4-diphenylsulfone tetracarboxylic acid dianhydride (DSDA), and the diamine is 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), It is one or a mixture of two or more of 3,4'-diaminodiphenylmethane (3,4'-MDA), 4,4'-diaminodiphenylmethane (4,4'-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB), 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether (6FODA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP); or prepared by mixing at least two polyamic acid solutions; the solid content of the polyamic acid solution is 5 to 40 wt%; The electrospinning parameters are as follows: the radiation voltage is 15 to 100 kV, preferably 16 to 80 kV, more preferably 17 to 75 kV or 15 to 55 kV, and the receiving distance is 10 to 30 cm, a method of manufacturing.
[0093] 35. A method for manufacturing, characterized in that, in the 33rd embodiment, the maximum temperature of the thermal imidization process used in step B is 250 to 450°C, preferably 300 to 450°C, and the residence time is 0.1 to 30 minutes, or 1 to 30 minutes.
[0094] 36. A method for manufacturing, wherein in the 33rd embodiment, the binder of step C is one or more of aqueous PVDF emulsion, polyvinyl alcohol, polyethylene oxide, acrylic water-soluble adhesive, styrene-butadiene rubber, sodium carboxymethylcellulose, and polyvinylpyrrolidone; the weight parts of each component of the coating slurry are 1 to 3 parts by weight of binder, 89 to 52 parts by weight of solvent, and 10 to 45 parts by weight of polyimide; and the dispersion is water.
[0095] 37. A manufacturing method characterized in that, in the 33rd embodiment, one or both sides of a polyolefin separator are coated with polyimide in step D, and the coating method is one of electrostatic spraying, blade coating, extrusion coating, transfer coating, wire coating, dip coating, gravure, or microgravure coating.
[0096] 38. In the 32nd embodiment, the coating slurry comprises high-temperature resistant polymer microspheres or high-temperature resistant polymer microspheres and inorganic particles, and the manufacturing method is characterized by comprising the following steps:
[0097] (1) A step of formulating a mixed coating slurry containing high-temperature resistant polymer microspheres or high-temperature resistant polymer microspheres and inorganic particles;
[0098] (2) A step of coating the above coating slurry on one or both sides of a base film.
[0099] 39. In the 38th embodiment, the solid content of the coating slurry is 2 to 71.4 wt%, preferably 4 to 70 wt%, more preferably 10 to 62 wt%;
[0100] A method of manufacturing, wherein the viscosity of the coating slurry is 20 to 7000 cP, preferably 100 to 6000 cP, more preferably 150 to 5500 cP.
[0101] 40. In the 38th or 39th embodiment, the slurry solvent is one of a water-type solvent or an organic solvent, and
[0102] Preferably, the aqueous solvent comprises pure water or water and a mixed solution of at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, propylene glycol, butanol, and acetic acid;
[0103] Preferably, the method of preparation is characterized in that the organic solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, ethanol, isopropanol, ethylene carbonate, and dimethyl carbonate.
[0104] 41. A manufacturing method according to the 38th or 39th embodiment, wherein the coating method of the coating comprises at least one of electrostatic spraying, blade coating, rotary spraying, extrusion coating, transfer coating, dip coating, wire coating, gravure, or microgravure coating.
[0105] 42. In the 32nd embodiment, the coating slurry comprises high-temperature resistant polymer nanofibers and inorganic particles, and
[0106] (1) A step of formulating a coating slurry containing high-temperature resistant polymer nanofibers and inorganic particles;
[0107] (2) A manufacturing method comprising the step of coating the above coating slurry on one or both sides of a base film.
[0108] 43. A method for manufacturing, wherein in the 42nd embodiment, the coating slurry comprises 0.4 to 65 parts by weight of high-temperature resistant polymer nanofibers, 35 to 99.6 parts by weight of inorganic particles, and 100 to 5000 parts by weight of slurry solvent; and the sum of the parts by weight of the high-temperature resistant polymer nanofibers and inorganic particles is 100.
[0109] 44. In the 42nd or 43rd embodiment, the solid content of the coating slurry is 2 to 50 wt%, preferably 6 to 48 wt%, more preferably 10 to 43 wt%, and / or,
[0110] A method for manufacturing, wherein the viscosity of the coating slurry is 50 to 4000 cP, preferably 100 to 3500 cP, more preferably 200 to 3000 cP.
[0111] 45. In any one of the 42nd to 44th embodiments, the slurry solvent is one of an aqueous solvent or an organic solvent, and
[0112] Preferably, the aqueous solvent comprises pure water or a mixed solution of at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, and butanol;
[0113] Preferably, the method of preparation is characterized in that the organic solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, ethanol, isopropanol, ethylene carbonate, and dimethyl carbonate.
[0114] 46. A method of manufacturing, wherein in any one of the 42nd to 43rd embodiments, the coating slurry further comprises an additive selected from at least one of a binder, a surfactant, a dispersant, a wetting agent, an antifoaming agent, etc.
[0115] 47. In any one of the 42nd to 44th embodiments, the amount of slurry solvent is 100 to 5000 parts by weight, preferably 120 to 4000 parts by weight, most preferably 150 to 2900 parts by weight, and / or,
[0116] The amount of binder is 0.5 to 12.5 parts by weight, preferably 0.6 to 12 parts by weight, more preferably 1.0 to 9 parts by weight, and / or,
[0117] The amount of surfactant is 0.1 to 5 parts by weight, preferably 0.2 to 4.9 parts by weight, more preferably 0.4 to 4.7 parts by weight, and / or,
[0118] The amount of dispersant is 0.1 to 7 parts by weight, preferably 0.2 to 6.9 parts by weight, more preferably 0.4 to 6.4 parts by weight, and / or,
[0119] The amount of wetting agent is 0.05 to 5 parts by weight, preferably 0.06 to 4.9 parts by weight, more preferably 0.09 to 4.7 parts by weight, and / or,
[0120] A method of manufacturing in which the amount of a defoaming agent is 0.1 to 4 parts by weight, preferably 0.2 to 3.9 parts by weight, more preferably 0.4 to 3.5 parts by weight.
[0121] 48. A manufacturing method in any one of the 42nd to 45th embodiments, wherein the coating method of the coating comprises at least one of electrostatic spraying, blade coating, rotary spraying, extrusion coating, transfer coating, dip coating, wire coating, gravure, or microgravure coating.
[0122] 49. A coating slurry comprising a slurry solvent and at least two of the following:
[0123] b2.1 High-temperature resistant polymer microspheres,
[0124] b2.2 High-temperature resistant polymer nanofibers, and
[0125] b2.3 inorganic particles.
[0126] 50. A coating slurry according to the 49th embodiment, comprising a high-temperature resistant polymer nanofiber, an inorganic particle, and a slurry solvent, wherein the high-temperature resistant polymer nanofiber is 0.4 to 65 parts by weight, the inorganic particle is 35 to 99.6 parts by weight, and the sum of the parts by weight of the high-temperature resistant polymer nanofiber and the inorganic particle is 100.
[0127] 51. In the 49th or 50th embodiment, the solid content of the coating slurry is 2 to 50 wt%, preferably 6 to 48 wt%, more preferably 10 to 43 wt%, and / or,
[0128] A coating slurry having a viscosity of 50 to 4000 cP, preferably 100 to 3500 cP, more preferably 200 to 3000 cP.
[0129] 52. In either the 49th or 50th embodiment, the slurry solvent is one of an aqueous solvent or an organic solvent, and
[0130] Preferably, the aqueous solvent comprises pure water or a mixed solution of at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, and butanol;
[0131] Preferably, the coating slurry is characterized in that the organic solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, ethanol, isopropanol, ethylene carbonate, and dimethyl carbonate.
[0132] 53. A coating slurry in any one of the 49th to 51st embodiments, wherein the coating slurry further comprises an additive selected from at least one of a binder, a surfactant, a dispersant, a wetting agent, an antifoaming agent, etc.
[0133] 54. In any one of the 49th to 51st embodiments, the amount of slurry solvent is 100 to 5000 parts by weight, preferably 120 to 4000 parts by weight, most preferably 150 to 2900 parts by weight, and / or,
[0134] The amount of binder is 0.5 to 12.5 parts by weight, preferably 0.6 to 12 parts by weight, more preferably 1.0 to 9 parts by weight, and / or,
[0135] The amount of surfactant is 0.1 to 5 parts by weight, preferably 0.2 to 4.9 parts by weight, more preferably 0.4 to 4.7 parts by weight, and / or,
[0136] The amount of dispersant is 0.1 to 7 parts by weight, preferably 0.2 to 6.9 parts by weight, more preferably 0.4 to 6.4 parts by weight, and / or,
[0137] The amount of wetting agent is 0.05 to 5 parts by weight, preferably 0.06 to 4.9 parts by weight, more preferably 0.09 to 4.7 parts by weight, and / or,
[0138] A coating slurry in which the amount of a defoaming agent is 0.1 to 4 parts by weight, preferably 0.2 to 3.9 parts by weight, more preferably 0.4 to 3.5 parts by weight.
[0139] 55. A lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the separator is a coated and modified composite separator described in any one of embodiments 1 to 31 or a coated and modified composite separator manufactured by a method described in any one of embodiments 32 to 48.
[0140] 56. As a coated and modified composite separation membrane,
[0141] The above-mentioned coated and modified composite separation membrane comprises a base membrane and a coating layer, and
[0142] The above coating layer is coated on any one or both sides of the base film, and
[0143] The above coating layer is high-temperature resistant polymer nanofibers and
[0144] b2.1 High-temperature resistant polymer microspheres, and
[0145] b2.3 Coated and modified composite separation membrane characterized by comprising at least one of inorganic particles.
[0146] 57. A method for manufacturing a coated and modified composite separation membrane as described in the 56th embodiment, wherein the method comprises:
[0147] (1) A step of formulating a coating slurry containing high-temperature resistant polymer nanofibers and one or more of the following:
[0148] b2.1 High-temperature resistant polymer microspheres, and
[0149] b2.3 Inorganic particles;
[0150] (2) A manufacturing method comprising the step of coating the above coating slurry on one or both sides of a base film.
[0151] 58. A coating slurry comprising a slurry solvent, a high-temperature resistant polymer nanofiber, and at least one of the following.
[0152] b2.1 High-temperature resistant polymer microspheres, and
[0153] b2.3 inorganic particles.
[0154] 59. As a coated and modified composite separation membrane,
[0155] The above-mentioned coated and modified composite separation membrane comprises a base membrane and a coating layer, and
[0156] The above coating layer is coated on any one or both sides of the base film, and
[0157] The above coating layer is,
[0158] b2.1 High-temperature resistant polymer microspheres,
[0159] b2.2 High-temperature resistant polymer nanofibers, and
[0160] b2.3 Coated and modified composite separation membrane characterized by comprising at least one of inorganic particles.
[0161] 60. A method for manufacturing a coated and modified composite separation membrane as described in the 59th embodiment, wherein the method comprises:
[0162] (1) A step of formulating a coating slurry comprising the following:
[0163] b2.1 High-temperature resistant polymer microspheres,
[0164] b2.2 High-temperature resistant polymer nanofibers, and
[0165] b2.3 Inorganic particles;
[0166] (2) A manufacturing method comprising the step of coating the above coating slurry on one or both sides of a base film.
[0167] 61. Slurry solvent; and
[0168] b2.1 High-temperature resistant polymer microspheres,
[0169] b2.2 High-temperature resistant polymer nanofibers, and
[0170] b2.3 Coated and modified composite separation membrane characterized by comprising at least one of inorganic particles.
[0171] General explanation and definition of terms
[0172] The endpoints and any range values disclosed herein are not limited to exact ranges or values, but should be understood to include values close to such ranges or values. In the case of numeric ranges, one or more new numeric ranges may be obtained by combining the endpoint values of each range, the endpoint values of each range, and individual point values, and by combining the individual point values, and such numeric ranges are deemed to be specifically disclosed herein.
[0173] The foregoing description of the embodiments is provided for illustrative and illustrative purposes only. It is not intended to exhaust or limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment and, where applicable, may be interchangeable and used in other selected embodiments even if not explicitly shown or described. They may also be modified in various ways. Such modifications should not be construed as departing from the content of the present disclosure, and all such modifications are intended to be included within the scope of this application.
[0174] A. Base membrane
[0175] In this application, the type of base film is not particularly limited and any type of base film is possible; the base film is a base film coated with inorganic particles, such as a polymer base film or a ceramic base film, and the ceramic base film is identical to the conventional ceramic base film mentioned in the art, comprising both the polymer base film and a ceramic layer coated on at least one surface of the polymer base film. In some embodiments, the thickness of the base film is 1.5 to 40 μm, preferably 2.0 to 35 μm, more preferably 3.5 to 30 μm. The thickness of the base film is preferably 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 7 μm or more, 9 μm or more, or 12 μm or more, and the thickness of the base film is preferably 37 μm or less, 35 μm or less, 33 μm or less, 30 μm or less, 28 μm or less, or 26 μm or less.
[0176] Examples of polymer base films include, but are not limited to, at least one of polyolefin base films, cellulose base films, polyester base films, aramid base films, polyimide base films, and organic-inorganic hybrid base films. In some embodiments, the polymer base film comprises a monolayer, a bilayer, or a multilayer, and the polymer base films included in each layer may be the same or different. In some embodiments, in the case of a bilayer polymer film or a multilayer polymer base film, the thickness of each layer may be the same or different from the thickness of the other layer. In some embodiments, in the case of a bilayer polymer base film or a multilayer polymer base film, each layer may be manufactured by the same or different processes, e.g., co-extrusion and / or lamination. In some embodiments, the polymer base film comprises a polyolefin base film, and the polyolefin may include, but is not limited to, polyethylene, polypropylene, polybutylene, copolymers of said polyolefins, and blends thereof.
[0177] In some embodiments, the polyolefin may be an ultra-low molecular weight, low molecular weight, intermediate molecular weight, high molecular weight, or ultra-high molecular weight polyolefin. For example, the ultra-high molecular weight polyolefin may have a molecular weight of 450,000 (450k) or more, for example, 500k or more, 600k or more, 700k or more, 800k or more, 1 million or more, 2 million or more, 3 million or more. The high molecular weight polyolefin may have a molecular weight in the range of 250k to 450k, for example, 250k to 400k, 250k to 350k, or 250k to 300k. Intermediate molecular weight polyolefins may have molecular weights ranging from 150k to 250k, for example, 150k to 225k, 150k to 200k, 150k to 200k, etc. Low molecular weight polyolefins may have molecular weights ranging from 100k to 150k, for example, 100k to 125k. Ultra-low molecular weight polyolefins may have molecular weights of less than 100k. The above figures are weight-average molecular weights. Polyolefin separators may have non-limiting compositions such as PP, PE, PP / PP, PP / PE, PE / PP, PE / PE, PE / PP / PE, etc.
[0178] According to the present invention, there are no special requirements for the inorganic particle coating layer, such as a ceramic layer, in the inorganic particle coating base film, and a ceramic layer generally used in the field can be selected. The ceramic particles of the ceramic layer may include at least one of Al2O3 (including α, β, and γ types), SiO2, BaSO4, BaO, titanium dioxide (TiO2, rutile or anatase), CuO, MgO, Mg(OH)2, LiAlO2, ZrO2, carbon nanotubes (CNT), BN, SiC, Si3N4, WC, BC, AlN, Fe2O3, BaTiO3, MoS2, V2O5, PbTiO3, TiB2, CaSiO3, molecular sieve (ZSM-5), clay, boehmite, and kaolin, preferably at least one of Al2O3, SiO2, and BaSO4, but are not limited thereto.
[0179] The separator disclosed in the present invention may further contain a filler, an elastomer, a wetting agent, a lubricant, a flame retardant, a nucleating agent, an antioxidant, a coloring agent, and / or other additional components suitable for the purpose of the present invention. For example, the substrate may contain a filler such as calcium carbonate, zinc oxide, diatomaceous earth, talc, kaolin, synthetic silica, mica, clay, boron nitride, silicon dioxide, titanium dioxide, barium sulfate, aluminum hydroxide, magnesium hydroxide, etc., or a combination thereof. The elastomer may include ethylene-propylene (EPR), ethylene-propylene-diene (EPDM), styrene-butadiene (SBR), styrene-isoprene (SIR), ethylidene norbornene (ENB), epoxy resin, and polyurethane, or a combination thereof. Wetting agents may include ethoxylated alcohols, primary polymeric carboxylic acids, glycols (e.g., polypropylene glycol and polyethylene glycol), functionalized polyolefins, etc. Lubricants may include silicones, fluoropolymers, oleamides, stearamides, erucamides, calcium stearate, lithium stearate, or other metal stearates. Flame retardants may include brominated flame retardants, ammonium phosphate, magnesium hydroxide, aluminum oxide trihydrate, and phosphate esters. Nucleating agents may include any nucleating agent that is not consistent with the purpose of the present invention.
[0180] B. Coating layer and coating slurry
[0181] The coating layer of the present invention comprises at least two of the following: high-temperature resistant polymer microspheres, high-temperature resistant polymer nanofibers, and inorganic particles.
[0182] In some embodiments, the thickness of the coating layer is 0.2 to 10 μm, and the thickness of the coating layer is preferably 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.7 μm or more, 1 μm or more, or 1.2 μm or more, and the thickness of the coating layer is preferably 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less. If the thickness of the coating layer is lower than 0.2 μm, the thermal dimensional stability, electrolyte retention rate, and capacity retention rate of the modified separator are reduced; if the thickness of the coating layer is thicker than 10 μm, the coating difficulty increases, and at the same time, the electrolyte retention rate of the electrolyte also increases, resulting in a lower energy density of the battery.
[0183] In some embodiments, the coating layer and / or coating slurry comprises high-temperature resistant polymer nanofibers and inorganic particles. The coating layer comprises 0.4 to 65 parts by weight of high-temperature resistant polymer nanofibers and 35 to 99.6 parts by weight of inorganic particles; the sum of the parts by weight of the high-temperature resistant polymer nanofibers and inorganic particles is 100. In some embodiments, the part by weight of the high-temperature resistant polymer nanofibers in the coating layer is preferably 1 to 64, 2 to 63, 3 to 62, 4 to 61, 5 to 59, or 7 to 58. In some embodiments, the part by weight of the inorganic particles in the coating layer is preferably 36 to 99, 37 to 98, 38 to 97, 39 to 96, 41 to 95, or 42 to 93.
[0184] In some embodiments, the coating layer and / or coating slurry comprises high-temperature resistant polymer microspheres and inorganic particles. The coating layer comprises 0.1 to 100 parts by weight of high-temperature resistant polymer microspheres and 99.9 to 0 parts by weight of inorganic particles, preferably 0.1 to 99.9 parts by weight of high-temperature resistant polymer microspheres and 99.9 to 0.1 parts by weight of inorganic particles, and the sum of the parts by weight of the high-temperature resistant polymer microspheres and inorganic particles is 100. In some embodiments, the part by weight of the high-temperature resistant microspheres in the coating layer is preferably 0.3 to 100, 1 to 100, 3 to 100, 5 to 100, 7 to 100, or 10 to 100. In some embodiments, the weight portion of inorganic particles in the coating layer is preferably 99.7 to 0, 99 to 0, 97 to 0, 95 to 0, 93 to 0, or 90 to 0.
[0185] In some embodiments, the coating layer and / or coating slurry comprises high-temperature resistant polymer microspheres, or high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers.
[0186] In some embodiments, the coating layer and / or coating slurry comprises at least one of high-temperature resistant polymer nanofibers, high-temperature resistant polymer microspheres, and inorganic particles. In some embodiments, the coating layer and / or coating slurry comprises high-temperature resistant polymer microspheres, high-temperature resistant polymer nanofibers, and inorganic particles. The integration of high-temperature resistant polymer nanofibers forms a network structure, enhances the integrity of the coating, and can avoid the problem of fragmentation of a single component of the microsphere structure due to binder failure at high temperatures.
[0187] In some embodiments, the coating slurry comprises high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers, wherein the high-temperature resistant polymer within the high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers is polyimide. In the above embodiments, a method for manufacturing a polyolefin composite separator modified by coating with polyimide comprises the following steps:
[0188] A: A step of preparing a polyamic acid solution by low-temperature condensation polymerization in a polar aprotic solvent with an intrinsic viscosity controlled to 0.01 to 1 dl / g, using a dianhydride and a diamine as monomers; subsequently, a step of preparing a polyamic acid material having a nanofiber / microsphere composite form by using a template method, spray drying technique, electrospinning technique, blowing spinning technique, or blowing-assisted electrospinning, and adjusting spinning parameters as necessary;
[0189] B: A step of thermally imidizing the polyamic acid material manufactured in Step A by high-temperature heat treatment to produce a polyimide material;
[0190] C: Step of formulating the coating slurry: Dispersing the polyimide material prepared in Step B into a dispersion and stirring uniformly; adding a binder to the polyimide dispersion and stirring uniformly at a stirring speed of 500 to 30,000 rpm;
[0191] D: A step of uniformly applying the coating slurry obtained in step C to the surface of the base film;
[0192] E: A step of drying the composite membrane obtained through the treatment of step D, wherein the drying temperature is 50 to 100°C and the drying time is 0.1 minutes to 12 hours, or 2 minutes to 12 hours.
[0193] For the polyamic acid solution used in Step A, the dianhydride is one or a mixture of two or more of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (α-BPDA), 4,4'-diphenyl ether dianhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), hexafluorodianhydride (6FDA), bisphenol A diether dianhydride (BPADA), and 3,3,4,4-diphenylsulfone tetracarboxylic acid dianhydride (DSDA), and the diamine is 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), It is one or a mixture of two or more of 3,4'-diaminodiphenylmethane (3,4'-MDA), 4,4'-diaminodiphenylmethane (4,4'-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB), 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether (6FODA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP); or prepared by mixing at least two polyamic acid solutions; the solid content of the polyamic acid solution is 5 to 40 wt%; The electrospinning parameters are as follows: the radiation voltage is 15 to 100 kV, preferably 16 to 80 kV, more preferably 17 to 75 kV or 15 to 55 kV, and the receiving distance is 10 to 30 cm.
[0194] The thermal imidization process used in step B has a maximum temperature of 250 to 450°C, preferably 300 to 450°C, and a residence time of 0.1 to 30 minutes, or 1 to 30 minutes.
[0195] The binder of step C is one or more of aqueous PVDF emulsion, polyvinyl alcohol, polyethylene oxide, acrylic water-soluble adhesive, styrene-butadiene rubber, sodium carboxymethylcellulose, and polyvinylpyrrolidone; the weight parts of each component of the coating slurry are 1 to 3 parts by weight of binder, 89 to 52 parts by weight of solvent, and 10 to 45 parts by weight of polyimide; and the dispersion is water.
[0196] In step D, one or both sides of the polyolefin separator are coated with polyimide, and the coating method is one of electrostatic spraying, blade coating, extrusion coating, transfer coating, wire coating, dip coating, and gravure or microgravure coating.
[0197] In some embodiments, the coating layer and / or coating slurry further comprise an additive selected from at least one of a binder, a surfactant, a dispersant, a wetting agent, an antifoaming agent, etc.
[0198] The binder comprises, but is not limited to, at least one of polyvinylidene fluoride and its copolymer, polyvinyl alcohol, polyacrylate, styrene-butadiene rubber, carboxymethylcellulose and its salt, polyvinylpyrrolidone, and polyimide. The amount of adhesive is 0.5 to 12.5 parts by weight. In some embodiments, the amount of binder is preferably 0.6 to 12, 0.7 to 11, 0.8 to 10, or 1.0 to 9 parts by weight.
[0199] The surfactant comprises, but is not limited to, at least one of fluorocarbon surfactants, nonionic surfactants, cationic surfactants, and anionic surfactants, preferably perfluoroalkyl ether alcoholamine salts, perfluoroalkyl ether quaternary ammonium salts, potassium perfluoroalkyl ether carboxylate fluorocarbon surfactants, and polyethylene glycol type, polyol type, block copolyether, and special polyether nonionic surfactants. The amount of surfactant is 0.1 to 5 parts by weight. In some embodiments, the surfactant is preferably used in an amount of 0.2 to 4.9, 0.3 to 4.8, 0.4 to 4.7, or 0.6 to 4.5 parts by weight.
[0200] The dispersant comprises, but is not limited to, at least one of tris(2-ethylhexyl)phosphate, sodium lauryl sulfate, methylpentanol, cellulose derivatives, polyacrylamide, guar gum, fatty acid polyethylene glycol esters, and cellulose ethers, preferably hydroxypropyl methylcellulose or polyacrylamide. The amount of the dispersant is 0.1 to 7 parts by weight. In some embodiments, the dispersant is preferably used in an amount of 0.2 to 6.9, 0.3 to 6.8, 0.4 to 6.4, or 0.6 to 6.0 parts by weight.
[0201] The wetting agent comprises at least one of monohydric alcohols, dihydric alcohols, and trihydric alcohols; preferably, but not limited to, at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, and butanol. The amount of the wetting agent is 0.05 to 5 parts by weight. In some embodiments, the amount of the wetting agent is preferably 0.06 to 4.9, 0.07 to 4.8, 0.09 to 4.7, or 0.11 to 4.3 parts by weight.
[0202] The defoamer comprises at least one of alcohols, fatty acids and fatty acid esters, amides, phosphate esters, silicones, polyethers, and polyether-modified polysiloxane defoamers; preferably, at least one of monoalkyls, dialkyl phosphates, alkyl fluoride phosphates, and polyether-modified silicone defoamers, but is not limited thereto. The amount of defoamer is 0.1 to 4 parts by weight. In some embodiments, the amount of defoamer is preferably 0.2 to 3.9, 0.3 to 3.7, 0.4 to 3.5, or 0.6 to 3.3 parts by weight.
[0203] The coating method of the above coating is not particularly limited, but includes at least one of electrostatic spraying, blade coating, rotary spraying, extrusion coating, transfer coating, dip coating, wire coating, gravure, or microgravure coating; preferably includes at least one of extrusion coating, gravure coating, or microgravure coating, but is not limited thereto.
[0204] In some embodiments, the base film coated with the coating slurry is dried. The drying temperature is 40 to 210°C, preferably 50 to 200°C, and the drying time is 0.1 to 60 minutes, 1 to 60 minutes, or 5 to 50 minutes. Oven drying is preferred as the drying method.
[0205] b.1 High-temperature resistant polymer microspheres
[0206] High-temperature resistant polymer microspheres include unmodified high-temperature resistant polymer microspheres, surface-modified high-temperature resistant polymer microspheres, and / or inorganic hybrid high-temperature resistant polymer microspheres.
[0207] The particle size of the high-temperature resistant polymer microsphere is 3 to 20,000 nm, preferably 5 nm or more, 7 nm or more, 9 nm or more, 12 nm or more, 15 nm or more, 20 nm or more, preferably 50 nm or less, 11,000 nm or less, 13,000 nm or less, 15,000 nm or less, or 18,000 nm or less.
[0208] The method for manufacturing high-temperature resistant polymer microspheres is not particularly limited and includes, but is not limited to, electrostatic spraying, phase separation, template method, precipitation method, blowing method, blowing-assisted electrospinning, centrifugation method, self-assembly method, solution spinning, in situ synthesis method, and reprecipitation method. In some embodiments, electrostatic spraying is used to manufacture high-temperature resistant polymer microspheres. The concentration of the polymer being spun in the polymer solution used for electrostatic spraying is 3 to 30 wt%, more preferably 8 to 20 wt%. When the relative molecular mass of the polymer is fixed and other conditions are constant, the concentration of the spinning solution is a critical factor affecting the entanglement of molecular chains in the solution.
[0209] The polymers of the unmodified high-temperature resistant polymer microspheres, surface-modified high-temperature resistant polymer microspheres and inorganic hybrid high-temperature resistant polymer microspheres include, but are not limited to, at least one of P84, polyetherimide, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylidene fluoride, polyvinylidene fluoride copolymer, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polytetrafluoroethylene, polyimide, polyester, cellulose, polyether ether ketone, polyaryl ether, polyamide, and polybenzimidazole.
[0210] Polyimide microspheres are preferred. The polyimide in the polyimide microspheres is prepared by homopolycondensation and copolycondensation of a raw material mixture containing a polybasic acid anhydride and a polyamine.
[0211] Surface-modified high-temperature resistant polymer microspheres include, but are not limited to, inorganic surface-modified high-temperature resistant polymer microspheres, high-temperature resistant polymer microspheres having polar groups after surface treatment, or high-temperature resistant polymer microspheres surface-coated with a functionalized organic material layer containing polar group(s). The polar groups include, but are not limited to, at least one of hydroxyl, carboxyl, sulfonic acid groups, amino, phosphate ester groups, halogens, and nitro groups. The functionalized organic material containing polar group(s) includes, but is not limited to, at least one of polyphosphazene, polyacrylonitrile, polyphosphoric acid, polysiloxane, polyester polymer, polyetherimide, polyether ether ketone, polyaryl ether, and polybenzimidazole, and aromatic sulfonic acid derivatives, e.g., 8-aminopyrene-1,3,6-trisulfonic acid and salts thereof. It should be noted that the surface modification mentioned above is not grafted onto the original particles to manufacture a core-shell structure. Compared to core-shell structured particles, which are difficult and costly to manufacture, the surface modification of the present invention is simpler to manufacture, has fewer components, and is less expensive to process.
[0212] The inorganic hybrid high-temperature resistant polymer microspheres contain inorganic materials. The inorganic materials used for surface modification and the inorganic hybrid high-temperature resistant polymer microspheres include, but are not limited to, at least one of alumina, boehmite, magnesium oxide, zirconia, barium titanate, titanium dioxide, silica, magnesium hydroxide, and zinc oxide.
[0213] The inorganic particles within the coating layer include, but are not limited to, at least one of ceramic, boehmite, metal oxide, metal hydroxide, metal carbonate, silicate, kaolin, talc, mineral, and glass. In some embodiments, the inorganic particles include at least one of boehmite, alumina, silica, barium titanate, titanium dioxide, zinc oxide, magnesium oxide, magnesium hydroxide, zirconia, or oxide solid electrolyte. Additionally, the oxide solid electrolyte includes at least one of perovskite-type, NASICON-type, LISICON-type, garnet-type, and LiPON-type electrolytes.
[0214] b.2 High-temperature resistant polymer nanofibers
[0215] High-temperature resistant polymer nanofibers include unmodified high-temperature resistant polymer nanofibers, surface-modified high-temperature resistant polymer nanofibers, and / or inorganic hybrid high-temperature resistant polymer nanofibers.
[0216] The diameter of the high-temperature resistant polymer nanofiber is 5 to 1500 nm, preferably 6 nm or more, 7 nm or more, 8 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more, and preferably 1450 nm or less, 1400 nm or less, 1350 nm or less, 1300 nm or less, or 1200 nm or less. The length of the high-temperature resistant polymer nanofiber is 0.5 to 1000 μm, preferably 0.6 μm or more, 1.0 μm or more, 3.0 μm or more, 5.0 μm or more, 7.0 μm or more, or 10.0 μm or more, preferably 950 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, or 600 μm or less. The aspect ratio of the high-temperature resistant polymer nanofiber is 5 to 2000, preferably 10 to 1500, more preferably 20 to 500.
[0217] The method for manufacturing high-temperature resistant polymer nanofibers is not subject to any particular limitations and includes, but is not limited to, at least one of electrospinning, phase separation, template method, precipitation method, blowing method, blowing-assisted electrospinning, centrifugation method, self-assembly method, solution spinning method, and in situ synthesis method. In some embodiments, electrospinning is used to manufacture high-temperature resistant polymer nanofibers. The concentration of the polymer spun in the polymer solution used in the electrospinning method is 3 to 30 wt%, more preferably 8 to 20 wt%. When the relative molecular mass of the polymer is fixed and other conditions are constant, the concentration of the spinning solution is a critical factor affecting the entanglement of molecular chains within the solution. In the present invention, effective spinnability can be secured when the concentration of the spinning solution is within the above range. Furthermore, as the concentration of the spinning solution increases, the degree of polymer entanglement increases, thereby improving spinnability. In the present invention, when electrospinning is performed using spinning solutions containing different polymers, the concentration of each spinning solution is independently selected within the concentration range.
[0218] Unmodified high-temperature resistant polymer nanofibers, surface-modified high-temperature resistant polymer nanofibers and inorganic hybrid high-temperature resistant polymer nanofibers include, but are not limited to, at least one of P84 nanofibers, polyetherimide nanofibers, polyvinylidene fluoride and its copolymer nanofibers, polyvinylidene fluoride-hexafluoropropylene nanofibers, polytetrafluoroethylene nanofibers, polyphosphazene nanofibers, polyacrylonitrile nanofibers, polyimide nanofibers, polyester nanofibers, cellulose nanofibers, polyetheretherketone nanofibers, polyarylether nanofibers, polyamide nanofibers, and polybenzimidazole nanofibers.
[0219] The polyimide in the polyimide nanofiber is prepared by homopolycondensation and copolycondensation of a raw material mixture containing polybasic acid anhydride and polyamine.
[0220] Surface-modified high-temperature resistant polymer nanofibers include, but are not limited to, inorganic surface-modified high-temperature resistant polymer nanofibers having polar groups after surface treatment, or high-temperature resistant polymer nanofibers surface-coated with a functionalized organic material layer containing polar group(s). The polar groups include, but are not limited to, at least one of hydroxyl, carboxyl, sulfonic acid group, amino, phosphate ester group, halogen, and nitro. Compounds used for surface treatment include, but are not limited to, oxidizing agents such as potassium permanganate, chlorate, potassium dichromate, etc.; acidic compounds such as sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, etc.; alkaline compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, barium hydroxide, strontium hydroxide, rubidium hydroxide, ammonia water, methylamine, ethylamine, dimethylamine, diethylamine, ethylenediamine, triethylamine, hydrazine hydrate, DMAB, salts of strong bases and weak acids, etc. Functionalized organic materials containing polar group(s) include, but are not limited to, at least one of polyphosphazene, polyacrylonitrile, polyphosphoric acid, polysiloxane, polyester polymer, polyetherimide, polyether ether ketone, polyaryl ether and polybenzimidazole, polymers, and aromatic sulfonic acid derivatives, e.g., 8-aminopyrene-1,3,6-trisulfonic acid and salts thereof.
[0221] Inorganic hybrid high-temperature resistant polymer nanofibers contain inorganic materials. The inorganic materials used for surface modification and inorganic hybrid high-temperature resistant polymer nanofibers include, but are not limited to, at least one of alumina, boehmite, magnesium oxide, zirconia, barium titanate, titanium dioxide, silica, magnesium hydroxide, and zinc oxide.
[0222] b.3 Inorganic particles
[0223] In the coating layer according to the present invention, the inorganic particles are selected from inorganic particles commonly used in the field. The inorganic particles in the coating layer include, but are not limited to, at least one of ceramics, metal oxides, metal hydroxides, metal carbonates, silicates, kaolin, talc, minerals, and glass. In some embodiments, the inorganic particles in the coating layer comprise, but are not limited to, at least one of Al2O3 (including α, β, and γ types), SiO2, BaSO4, BaO, titanium dioxide (TiO2, rutile or anatase), CuO, MgO, Mg(OH)2, LiAlO2, ZrO2, BN, SiC, Si3N4, WC, BC, AlN, Fe2O3, BaTiO3, MoS2, V2O5, PbTiO3, TiB2, CaSiO3, molecular sieve (ZSM-5), clay, boehmite, and kaolin, and preferably use at least one of Al2O3, boehmite, MgO, Mg(OH)2, titanium dioxide (TiO2, rutile or anatase), SiO2, and BaSO4. In some embodiments, the inorganic particles comprise at least one of boehmite, alumina, silica, barium titanate, titanium dioxide, zinc oxide, magnesium oxide, magnesium hydroxide, zirconia, or an oxide solid electrolyte. Additionally, the oxide solid electrolyte comprises at least one of a perovskite type, NASICON type, LISICON type, garnet type, and LiPON type electrolyte.
[0224] The average diameter of the inorganic particles is 10 nm to 5 μm, preferably 11 nm or more, 13 nm or more, 15 nm or more, 20 nm or more, 25 nm or more, or 30 nm or more, and preferably 4.9 μm or less, 4.7 μm or less, 4.5 μm or less, 4.3 μm or less, or 4.0 μm or less. In some embodiments, the inorganic particles have an average particle size of 10 nm to 5 μm, preferably 11 nm to 4.9 μm, and most preferably 15 nm to 4.5 μm.
[0225] C. Lithium-ion battery
[0226] The present invention further provides a lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the separator is the coated and modified composite separator.
[0227] The cathode consists of a cathode material for lithium-ion batteries, a conductive agent, and a binder. The cathode materials used include lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganate (LiMn2O4), lithium iron phosphate (LiFePO4), and lithium iron manganese phosphate (LiFe₂O₄). x Mn 1-x PO4), lithium nickel-cobalt-manganese (LiNi 1-x-y Co y Mn x O2), lithium nickel-cobalt-aluminate (LiNi 1-x-y Co y Al x O 2e It includes any cathode material that can be used in lithium-ion batteries, such as ).
[0228] The negative electrode consists of a negative electrode material for a lithium-ion battery, a conductive agent, and a binder. The negative electrode material used includes any negative electrode material that can be used in a lithium-ion battery, such as at least one of graphite, soft carbon, hard carbon, silicon carbon, silicon dioxide, and silicon carbon.
[0229] The binder comprises, but is not limited to, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, polyamic acid, polyimide, aramid fiber, etc.
[0230] The above conductive material is used to improve the conductivity of the electrode and includes, but is not limited to, at least one of natural graphite, artificial graphite, carbon black, carbon fiber, carbon nanotube, graphene, carbon nanofiber, metal powder, metal fiber, etc. Metallic copper, nickel, aluminum, silver, etc. may be used as metal powder and metal fiber.
[0231] The main improvement of the lithium-ion battery provided by the present invention is that it uses the aforementioned coated and modified composite separator, and the arrangement (connection method) of the positive electrode, negative electrode, separator, and electrolyte may be the same as that of the prior art known to those skilled in the art, so it is not described in detail herein.
[0232] The method for manufacturing a lithium-ion battery provided in the present invention comprises the step of stacking or winding a positive electrode, a separator, and a negative electrode in sequence into a cell, and then injecting an electrolyte into the cell and sealing it, wherein the separator is a coated and modified composite separator.
[0233] Examples
[0234] To clarify the purpose, technical solution, and advantages of the embodiments of the present invention, the technical solution of the embodiments of the present invention will be described clearly and completely below with reference to the drawings of the embodiments of the present invention. By definition, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work will also fall within the scope of protection of the present invention.
[0235] In the following embodiments of the present invention, the abbreviation C represents an inorganic particle, the abbreviation P represents a high-temperature resistant polymer nanofiber and / or microsphere, and the abbreviation CP represents a composite of an inorganic particle and a high-temperature resistant polymer nanofiber and / or microsphere.
[0236] The number preceding the abbreviation indicates the coating thickness, for example, 4C indicates an inorganic coating layer with a thickness of 4 μm, and 4CP indicates a composite coating layer of inorganic particles and high-temperature resistant polymer nanofibers and / or microspheres with a thickness of 4 μm.
[0237] In the embodiments of the present invention, the coating layer thickness refers to the thickness after drying.
[0238] shrinkage rate
[0239] The modified composite membrane is cut into 5cm × 5cm pieces, placed in an oven, and maintained at 150°C or 200°C for 30 minutes. Refer to the Chinese standard GB / T 36363-2018 for the thermal shrinkage test method. The thermal shrinkage of the membrane is measured in the longitudinal (MD) and transverse (TD) directions, and the larger value of the thermal shrinkage of the MD and TD is defined as the thermal shrinkage of the membrane.
[0240] Tensile strength measurement
[0241] The method for measuring the tensile strength of the modified composite membrane follows the Chinese standard GB / T 36363-2018. Measurements were performed on Type 2 samples with a width of (15±0.1) mm under conditions where the initial distance between clamps was (100±5) mm and the test speed was (250±10) mm / min. The maximum strength value during the tensile process of the sample was considered as the tensile strength, recorded, and compared. Tensile strength was measured in the longitudinal direction (MD) and the transverse direction (TD), respectively, and the lower value between the tensile strengths in MD and TD was defined as the tensile strength of the modified composite membrane.
[0242] Here, the 200°C tensile strength refers to the tensile strength tested according to the above method after measuring the thermal shrinkage rate after maintaining a sample of the modified composite membrane at 200°C for 30 minutes.
[0243] Transmittance measurement
[0244] The method for measuring the air permeability of a modified composite membrane follows the Chinese standard GB / T 36363-2018. For measurement, three modified composite membranes measuring 100mm x 100mm are taken. The modified composite membranes are placed in a Labthink Company BTY-B2P type air permeability tester to perform an air permeability test. The average value of the three test results is taken as the air permeability of the modified composite membrane.
[0245] porosity
[0246] Cut the modified composite membrane into a 2cm × 2cm square sample. The mass of the sample is W a After weighing, place in a vacuum oven and heat at 60°C for 2 hours to remove moisture. After drying, completely immerse the dried fiber membrane in n-butanol for at least 2 hours. The solvent on the membrane surface is completely absorbed through filter paper. Then, the mass of the membrane is W b It is measured as follows. Porosity is calculated using the following formula.
[0247]
[0248] In the above equation: ρ p : Density of modified composite membrane
[0249] ρ b : Density of n-butanol, 0.81 g / mL.
[0250] Ionic conductivity
[0251] The modified composite separator is cut into discs of the corresponding specifications. Its thickness is measured. It is placed in a vacuum oven set to 80°C and maintained at that temperature for 10 hours. The button battery is assembled inside a glove box with an argon atmosphere, in the order of shell, gasket, separator containing electrolyte, gasket, and shell. After mounting the battery, it is left undisturbed for 12 hours. AC impedance is measured using a chemical workstation. The amplitude is set to 5mV, the time to 2 seconds, and the test range to 1 to 10 5 It is Hz. The internal resistance R of the separator. d It can be obtained from the AC impedance diagram, and the ionic conductivity can be calculated according to the following equation.
[0252] δ=d / (R d *S), here R d is the internal resistance of the modified composite membrane, S is the area of the stainless steel gasket, and d is the thickness of the modified composite membrane.
[0253] Battery capacity retention rate
[0254] The entire battery is made using a nickel-rich 8-series NCM ternary material (S85E) and a negative electrode silicon oxide carbon 450: the mass ratio of active material (S85E): adhesive (PVDF): conductor (SP) on the positive electrode is 95:1.8:3.2, the solid content is 65 wt%, and the solvent is NMP; the mass ratio of active material (silicon oxide carbon 450): binder (SBR: CMC=2.5:1.5): conductor (SP) is 95:4.0:1.0, the solid content is 45 wt%, and the solvent is water. A 2Ah soft-packaged stacked battery was fabricated using the above electrode plates, and a cycle test was performed at 1C, and the ratio of the discharge capacity of the 100th cycle to the discharge capacity of the first cycle was defined as the capacity retention rate.
[0255] Experiment Series 1
[0256] Example 1.1
[0257] Preparation of PMDA / ODA system polyimide (PI) in fiber / microsphere composite form: Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and reacted in a 0°C ice bath with the solvent N,N-dimethylformamide (DMF) for 10 hours to obtain a clear and transparent polyamic acid solution with a mass concentration of 12%. The polyamic acid solution was electrospun in an electric field with an electric field strength of 1 kV / cm. After recovering the polyamic acid film through a stainless steel drum, the film was peeled off the drum and placed in a high-temperature furnace for imidization treatment. The heating program involved increasing the temperature from room temperature to 300°C at a rate of 5°C / min, maintaining the temperature at 300°C for 1 hour, then opening the furnace to allow natural cooling to room temperature.
[0258] Preparation of coating slurry: A coating slurry was prepared by mixing a polymer binder, a mixed solvent of water and ethanol, and a polyimide film in a weight ratio of 1:79:20. First, 0.8g of polyimide film was weighed and dispersed in 3.16g of a mixed solvent of water and ethanol to obtain a polyimide dispersion. Subsequently, 0.04g of CMC was weighed and added to the polyimide dispersion, and the mixture was stirred for 10 minutes at a rotation speed of 1000 rpm using a high-speed homogenizer.
[0259] Coating: The stirred PI slurry was defoamed by placing it in a vacuum oven for 1 hour. Subsequently, the slurry was uniformly coated on one side of a PE membrane and a single-sided ceramic PE membrane using microgravure coating. The thicknesses of the base membranes were 7 and 7+2 μm, denoted as 7 and 7+2C, respectively. After coating, the coating thickness was 3 μm, and the membrane thicknesses were 10 μm and 12 μm, denoted as 7+3P and 7+2C+3P, respectively.
[0260] Drying: The separator coated with PI slurry was placed in a constant temperature oven to dry. The drying temperature was 50 to 100°C and the drying time was 0.5 to 12 hours. The obtained fiber / microsphere composite polyimide is shown in Fig. 1, and the shape of the obtained fiber / microsphere composite structure PI-coated polyolefin composite separator is shown in Fig. 2.
[0261] After maintaining at 150°C for 30 minutes, the thermal shrinkage rate of the PE base membrane was 85%, and the thermal shrinkage rate of the PE / PI composite membrane was 4%; the thermal shrinkage rate of the single-sided ceramic PE separator was 6%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0262] After maintaining at 200°C for 30 minutes, the thermal shrinkage rate of the PE base membrane was 87%, and the thermal shrinkage rate of the PE / PI composite membrane was 4.5%; the thermal shrinkage rate of the single-sided ceramic PE separator was 7%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0263] Example 1.2
[0264] Preparation of PMDA / 4,4'-MDA system polyimide with fiber / microsphere composite form: Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (MDA) were weighed in a 1:1 molar ratio and reacted in a 0°C ice bath with the solvent N,N-dimethylformamide (DMF) for 10 hours to obtain a clear and transparent polyamic acid solution with a mass concentration of 12%. The polyamic acid solution was electrospun in an electric field with an electric field strength of 1 kV / cm. After recovering the polyamic acid film through a stainless steel drum, the film was peeled off the drum and placed in a high-temperature furnace for imidization treatment. The heating program involved increasing the temperature from room temperature to 300°C at a rate of 5°C / min, maintaining the temperature at 300°C for 1 hour, then opening the furnace to allow natural cooling to room temperature.
[0265] Preparation of coating slurry: A coating slurry was prepared by mixing a polymer binder, a mixed solvent of water and ethanol, and a polyimide film in a weight ratio of 1:79:20. First, 0.8g of polyimide film was weighed and dispersed in 3.16g of a mixed solvent of water and ethanol to obtain a polyimide dispersion. Subsequently, 0.04g of CMC was weighed and added to the polyimide dispersion, and the mixture was stirred for 10 minutes at a rotation speed of 1000 rpm using a high-speed homogenizer.
[0266] Coating: The stirred PI slurry was placed in a vacuum oven for 1 hour for defoaming. Subsequently, the slurry was uniformly coated on one side of a PE separator and a single-sided ceramic PE separator using microgravure coating.
[0267] Drying: The separator coated with the PI slurry was placed in a constant temperature oven for drying. The drying temperature was 50 to 100°C, and the drying time was 0.5 to 12 hours. The thickness of the base membrane was 7 and 7+2 μm, denoted as 7 and 7+2C, respectively. After coating, the coating thickness was 3 μm, and the membrane thickness was 10 μm and 12 μm, denoted as 7+3P and 7+2C+3P, respectively. The obtained fiber / microsphere composite polyimide is shown in Fig. 3, and the shape of the obtained fiber / microsphere composite PI-coated polyolefin composite separator is shown in Fig. 4.
[0268] After maintaining at 150°C for 30 minutes, the thermal shrinkage rate of the PE base membrane was 85%, and the thermal shrinkage rate of the PE / PI composite membrane was 3.5%; the thermal shrinkage rate of the single-sided ceramic PE separator was 6%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0269] After maintaining at 200℃ for 30 minutes, the thermal shrinkage rate of the PE base membrane was 87%, and the thermal shrinkage rate of the PE / PI composite membrane was 4%; the thermal shrinkage rate of the single-sided ceramic PE separator was 7%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0270] Example 1.3
[0271] Preparation of PMDA / p-PDA system polyimide having a fiber / microsphere composite form: Monomers pyromellitic acid dianhydride (PMDA) and p-phenylenediamine (p-PDA) were weighed in a 1:1 molar ratio and reacted in a 0°C ice bath with the solvent N,N-dimethylformamide (DMF) for 10 hours to obtain a clear and transparent polyamic acid solution with a mass concentration of 12%. The polyamic acid solution was electrospun in an electric field with an electric field strength of 1 kV / cm. After recovering the polyamic acid film through a stainless steel drum, the film was peeled off the drum and placed in a high-temperature furnace for imidization treatment. The heating program involved increasing the temperature from room temperature to 300°C at a rate of 5°C / min, maintaining the temperature at 300°C for 1 hour, then opening the furnace to allow natural cooling to room temperature.
[0272] Preparation of coating slurry: A coating slurry was prepared by mixing a polymer binder, a mixed solvent of water and ethanol, and a polyimide film in a weight ratio of 1:79:20. First, 0.8g of polyimide film was weighed and dispersed in 3.16g of a mixed solvent of water and ethanol to obtain a polyimide dispersion. Subsequently, 0.04g of CMC was weighed and added to the polyimide dispersion, and the mixture was stirred for 10 minutes at a rotation speed of 1000 rpm using a high-speed homogenizer.
[0273] Coating: The stirred PI slurry was placed in a vacuum oven for 1 hour for defoaming. Subsequently, the slurry was uniformly coated on one side of a PE separator and a single-sided ceramic PE separator using microgravure coating.
[0274] Drying: The separator coated with the PI slurry was placed in a constant temperature oven to dry. The drying temperature was 50 to 100°C and the drying time was 0.5 to 12 hours. The thickness of the base membrane was 7 and 7+2 μm, denoted as 7 and 7+2C, respectively. After coating, the coating thickness was 3 μm, and the membrane thickness was 10 μm and 12 μm, denoted as 7+3P and 7+2C+3P, respectively. The polyimide having the obtained fiber / microsphere composite form is shown in Fig. 5, the form of the PI-coated polyolefin composite separator with the fiber / microsphere composite structure is shown in Fig. 6, and comparative photographs of the heat shrinkage of the obtained fiber / microsphere composite PI-coated polyolefin composite separator at various temperatures are shown in Fig. 7.
[0275] After maintaining at 150°C for 30 minutes, the thermal shrinkage rate of the PE base membrane was 85%, and the thermal shrinkage rate of the PE / PI composite membrane was 3%; the thermal shrinkage rate of the single-sided ceramic PE separator was 6%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0276] After maintaining at 200℃ for 30 minutes, the thermal shrinkage rate of the PE base membrane was 87%, and the thermal shrinkage rate of the PE / PI composite membrane was 3.2%; the thermal shrinkage rate of the single-sided ceramic PE separator was 7%, and the thermal shrinkage rate of the PI / PE / ceramic composite membrane was 0%.
[0277] Experiment Series 2
[0278] Example 2.1
[0279] Polyimide microspheres / ceramic-coated polyethylene separator
[0280] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a clear and transparent polyamic acid solution with a mass concentration of 6%. PAA microspheres were prepared from this using an electrostatic spray method. The obtained microspheres were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide microspheres.
[0281] (2) 10 g of polyimide microspheres (average particle size 800 nm), 90 g of ceramic, 1.5 g of sodium carboxymethyl cellulose binder, 200 g of a mixed solvent of water and ethanol (ethanol 5 wt%), 0.3 g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3 g of a dispersant hydroxypropylmethylcellulose, 0.06 g of a wetting agent glycerol, and 0.3 g of an antifoaming agent alkyl phosphate were weighed; the components were dissolved and uniformly dispersed by stirring to obtain a coating slurry.
[0282] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated polyethylene membrane was uniformly coated on one or both sides of a 7 μm polyethylene membrane using microgravure coating to obtain coated polyethylene membranes labeled 7+4CP and 7+4CP+4CP; the non-ceramic side of a 7+4 μm single-sided ceramic polyethylene membrane, labeled 7+4C+4P, which has a base membrane thickness of 7 μm, a ceramic coating thickness of 4 μm, and a coating thickness of 4 μm obtained from the coating slurry of (2).
[0283] (4) Drying: The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 0.5 hours. The shape of the obtained modified composite polyethylene separator is shown in Fig. 8.
[0284] Performance tests were performed on each of the above membranes, and the results are shown in Table 1 below:
[0285]
[0286] Example 2.2
[0287] Polyimide microspheres / boehmite-coated polypropylene separator
[0288] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a clear and transparent polyamic acid solution with a mass concentration of 20%. From this, polyamic acid microspheres were prepared using a blowing electrostatic spray method. The microspheres were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide microspheres.
[0289] (2) 80g of boehmite, 20g of polyimide microspheres (average particle size of microspheres: 200nm), and 6.4g of PVDF were weighed and dispersed in 450g of NMP to obtain a coating slurry.
[0290] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the 12 μm polypropylene membrane was uniformly coated on one or both sides using microgravure coating to obtain two types of coated polypropylene membranes.
[0291] (4) The coated polypropylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The composite separator coated on one side and modified on both sides obtained in step (3) were labeled as 12+3CP and 12+3CP+3CP, respectively. The non-ceramic side of the 12+3μm single-sided ceramic polypropylene separator was uniformly coated using the coating method according to step (3) and was labeled as 12+3C+3CP, which means that the base membrane thickness is 12μm, the ceramic coating thickness is 3μm, and the coating thickness obtained from the coating slurry of (2) is 3μm.
[0292] Performance tests were performed on each of the above membranes, and the results are shown in Table 2 below:
[0293]
[0294] Example 2.3
[0295] Hybrid polyimide microspheres / ceramic-coated polyethylene separator
[0296] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and added to the solvent N,N-dimethylformamide (DMF) to synthesize a clear and transparent polyamic acid solution (PAA) with a mass concentration of 10%. A 100 nm LATP solid electrolyte was dispersed in the PAA solution to obtain a dispersion of LATP and polyamic acid. The dispersion was electrostatically sprayed to obtain LATP / PAA hybrid microspheres. The microspheres were placed in a high-temperature furnace for imidation treatment. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain LATP / PI hybrid microspheres.
[0297] (2) 50g of LATP / PI hybrid microspheres (average particle size of microspheres: 300nm), 50g of ceramic, 5.0g of PVDF binder, 390g of a mixed solvent of water and ethanol (10wt% ethanol), 2.5g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 2.5g of a dispersant hydroxypropylmethylcellulose, and 0.1g of a wetting agent glycerol were weighed and uniformly stirred to obtain a coating slurry.
[0298] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated polyethylene membrane was obtained by uniformly coating both sides of a 7μm polyethylene membrane using extrusion coating.
[0299] (4) The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The separator was labeled as 7+2CP+2CP.
[0300] Performance tests were performed on the above-mentioned separator, and the results are shown in Table 3 below:
[0301]
[0302] Example 2.4
[0303] Polyacrylonitrile (PAN) microspheres / magnesium oxide coated polypropylene separator
[0304] (1) 7.3 g of polyacrylonitrile was dissolved in 92.7 g of N-methylpyrrolidone (NMP) and stirred to obtain a clear and transparent PAN solution with a mass concentration of 7.3%. PAN microspheres were prepared by blowing electrostatic spraying.
[0305] (2) 5g of PAN microspheres (average particle size of microspheres: 1000nm) and 95g of magnesium oxide were weighed and dispersed in 240g of water, then stirred at high speed to obtain a PAN microsphere / magnesium oxide dispersion. Next, 5.0g of sodium carboxymethylcellulose was weighed and dissolved in 150g of water until completely dissolved. The two slurries above were mixed and stirred uniformly to obtain a coating slurry.
[0306] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated polypropylene membrane was obtained by uniformly coating both sides of a 12 μm polypropylene membrane using microgravure coating.
[0307] (4) The coated polypropylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The thickness of the dried coating was 3 μm and the separator was labeled as 12+3CP+3CP.
[0308] Performance tests were performed on each of the above membranes, and the results are shown in Table 4 below:
[0309]
[0310] Example 2.5
[0311] Polyimide / Silica Microspheres / Li7La3Zr2O 12 (LLZO) Garnet-type solid oxide electrolyte-coated polyethylene separator
[0312] (1) 90 g of monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and added to the solvent N,N-dimethylformamide (DMF) to synthesize a clear and transparent polyamic acid solution with a mass concentration of 12%. 10 g of TEOS was added and the mixture was stirred uniformly. From this, polyamic acid microspheres were prepared using an electrostatic spray method. The microspheres were placed in a high-temperature furnace for imidization treatment. The heating program increased the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintained the temperature at 300°C for 1 hour to obtain polyimide / silica microspheres containing silica on the surface and inside.
[0313] (2) 1 g of polyimide / silica microspheres (average particle size of microspheres: 1300 nm), 99 g of LLZO, 5 g of polyacrylamide, 1.8 g of surfactant perfluoroalkyl ether quaternary ammonium salt, 0.5 g of dispersant hydroxypropylmethylcellulose, 0.5 g of wetting agent glycerol, and 0.2 g of defoaming agent were dissolved in 140 g of water and stirred sufficiently to obtain a coating slurry.
[0314] (3) The stirred coating slurry was placed in a vacuum oven for 1 hour for defoaming. Afterwards, the slurry was uniformly coated on both sides of a 7 μm polyethylene separator using a microgravure coating method.
[0315] (4) The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 55℃ and the drying time was 0.5 hours.
[0316] Performance tests were performed on the above-mentioned separator, and the results are shown in Table 5 below:
[0317]
[0318] Example 2.6
[0319] Polyimide nanosphere / boehmite-coated polyethylene composite separator
[0320] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a clear and transparent polyamic acid solution with a mass concentration of 10%. From this, polyamic acid (PAA) microspheres were prepared using an electrostatic blowing method. The temperature of the obtained microspheres was raised from room temperature to 300°C at a heating rate of 5°C / min and maintained for 1 hour to obtain polyimide microspheres.
[0321] (2) 20g of polyimide microspheres (average particle size of microspheres: 750nm), 80g of boehmite (average particle size 500nm), 1.5g of sodium carboxymethylcellulose, 175g of a mixed solvent of water and ethanol (ethanol 5wt%), 0.3g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3g of a dispersant hydroxypropyl methylcellulose, and 0.06g of a wetting agent glycerol were weighed and uniformly stirred to obtain a coating slurry.
[0322] (3) After defoaming the coating slurry by placing it in a vacuum oven for 1 hour, the coating was uniformly coated on both sides of a 7 μm polyethylene membrane using a microgravure coating method to obtain a coated and modified membrane.
[0323] (4) The coated and modified separator was placed in a constant temperature oven to dry. The drying temperature was 55°C and the drying time was 1 hour. The obtained modified composite polyethylene separator was denoted as 7+2CP+2CP.
[0324] The manufacturing process of Examples 2.7 to 2.14 was the same as that of Example 2.6, except that the inorganic particles and / or high-temperature resistant microspheres used in the coating were different.
[0325] The test performance results of Examples 2.6 to 2.14 are shown in Table 6.
[0326]
[0327] Example 2.15
[0328] Polyimide hybrid microsphere / barium titanate polyolefin composite separator
[0329] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10%. Nano barium titanate (mass ratio of PAA to titanium dioxide 95:5) was added to this solution and thoroughly stirred. From this, PAA hybrid microspheres were prepared using an electrostatic spray method. The obtained microspheres were imidized in a high-temperature furnace. The heating program was set from room temperature to 300°C at a heating rate of 5°C / min and maintained at 300°C for 1 hour to obtain polyimide / barium titanate microspheres.
[0330] Steps (2) to (4) are the same as in Example 2.6, except that the inorganic particles are changed to barium titanate.
[0331] Example 2.16
[0332] Polyetherimide microsphere / zinc oxide polyolefin composite separator (CP / PE / CP)
[0333] (1) 7.5 g of polyetherimide was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a polyetherimide solution with a mass concentration of 7.5%. From this, polyetherimide microspheres were prepared by electrostatic spraying.
[0334] Steps (2) to (4) are the same as in Example 2.6.
[0335] Example 2.17
[0336] Polyacrylonitrile (PAN) microsphere / silica polyolefin composite separator (CP / PE / CP)
[0337] (1) 7.5 g of polyacrylonitrile was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a PAN solution with a mass concentration of 7.5%. From this, polyacrylonitrile microspheres were prepared by electrostatic spraying.
[0338] Steps (2) to (4) are the same as in Example 2.6.
[0339] Example 2.18
[0340] P84 Microsphere / Zirconia Polyolefin Composite Separator (CP / PE / CP)
[0341] (1) 7.5 g of P84 was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a P84 solution with a mass concentration of 7.5%. From this, P84 microspheres were prepared by blowing atomization.
[0342] Steps (2) to (4) are the same as in Example 2.6.
[0343] Example 2.19
[0344] Polyester (Polyethylene Terephthalate PET) Microsphere / Kaolin Polyolefin Composite Separator (CP / PE / CP)
[0345] (1) 7.5g of PET was dissolved in 92.5g of xylenol and stirred to obtain a PET solution with a mass concentration of 7.5%. PET microspheres were prepared from this using an electrostatic spray method.
[0346] Steps (2) to (4) are the same as in Example 2.6.
[0347] Example 2.20
[0348] Polyimide nanosphere-coated polyethylene composite separator
[0349] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10%. From this, PAA microspheres were prepared using an electrostatic blowing method. The temperature of the obtained microspheres was raised from room temperature to 300°C at a heating rate of 5°C / min and maintained for 1 hour to obtain polyimide microspheres.
[0350] (2) 100g of polyimide microspheres (average particle size of microspheres: 750nm), 1.5g of sodium carboxymethylcellulose, 175g of a mixed solvent of water and ethanol (ethanol 5wt%), 0.3g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3g of a dispersant hydroxypropyl methylcellulose, and 0.06g of a wetting agent glycerol were weighed and uniformly stirred to obtain a coating slurry.
[0351] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated and modified membrane was obtained by uniformly coating both sides of a 7 μm polyethylene membrane using a microgravure coating method.
[0352] (4) The coated and modified separator was placed in a constant temperature oven to dry. The drying temperature was 55°C and the drying time was 1 hour. The obtained modified composite polyethylene separator was denoted as 7+2P+2P.
[0353]
[0354] Experiment Series 3
[0355] Example 3.1
[0356] Polyimide nanofiber / ceramic-coated polyethylene separator
[0357] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 6% in this example. PAA nanofibers were prepared by electrospinning. The obtained fibers were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide nanofibers.
[0358] (2) 10 g of polyimide nanofiber (average diameter of fiber 800 nm, aspect ratio in the range of 10 to 200), 90 g of ceramic, 1.5 g of sodium carboxymethyl cellulose binder, 200 g of a mixed solvent of water and ethanol (ethanol 5 wt%), 0.3 g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3 g of a dispersant hydroxypropylmethylcellulose, 0.06 g of a wetting agent glycerol, and 0.3 g of an antifoaming agent alkyl phosphate fluoride were weighed; the components were dissolved and uniformly dispersed by stirring to obtain a coating slurry.
[0359] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated polyethylene membrane was uniformly coated on one or both sides of the 7 μm polyethylene membrane using a microgravure coating method to obtain coated polyethylene membranes labeled 7+4CP and 7+4CP+4CP; the non-ceramic side of the 7+4 μm single-sided ceramic polyethylene membrane is labeled 7+4C+4P. The thickness of the base membrane was 7 μm.
[0360] (4) Drying: The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 0.5 hours. The shape of the obtained modified composite polyethylene separator is shown in Fig. 11.
[0361] Performance tests were performed on each of the above membranes, and the results are shown in Table 8 below:
[0362]
[0363] Example 3.2
[0364] Polyimide nanofiber / boemite-coated polypropylene separator
[0365] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and added to the solvent N,N-dimethylformamide (DMF) to synthesize a polyamic acid solution with a mass concentration of 20% in this example. Polyamic acid nanofibers were prepared using a blowing electrospinning method. The nanofibers were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide nanofibers.
[0366] (2) 80g of boehmite, 20g of polyimide nanofiber (average diameter of fiber 200nm, aspect ratio in the range of 10 to 200), and 6.4g of PVDF were weighed and dispersed in 450g of NMP to obtain a coating slurry.
[0367] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the 12 μm polypropylene membrane was uniformly coated on one side or both sides using a microgravure coating method to obtain two types of coated polypropylene membranes.
[0368] (4) The coated polypropylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The composite separator coated on one side and modified on both sides obtained in step (3) were labeled as 12+4CP and 12+4CP+4CP, respectively. The non-ceramic side of the 12+4μm single-sided ceramic polypropylene separator was uniformly coated using the coating method according to step (3) and was labeled as 12+4C+4CP, which means the base membrane thickness is 12μm, the ceramic coating thickness is 4μm, and the coating thickness obtained from the coating slurry of (2) is 4μm.
[0369] The form of the obtained modified composite polypropylene membrane coating is shown in Fig. 12.
[0370] Performance tests were performed on each of the above membranes, and the results are shown in Table 9 below:
[0371]
[0372] Example 3.3
[0373] Hybrid polyimide nanofiber / ceramic-coated polyethylene separator
[0374] (1) P84 was dissolved in the solvent N,N-dimethylacetamide (DMAc) to obtain a polyamic acid solution with a mass concentration of 10% in this example. A 100 nm LATP solid electrolyte was dispersed in the P84 solution to obtain a LATP and P84 dispersion. The dispersion was electrospun to obtain LATP / P84 hybrid nanofibers.
[0375] (2) 50g of LATP / P84 hybrid nanofiber (average diameter of fiber: 300nm, aspect ratio in the range of 20 to 400), 50g of ceramic, 5.0g of binder PVDF, 390g of water and ethanol mixed solvent (10wt% ethanol), 2.5g of surfactant perfluoroalkyl ether quaternary ammonium salt, 2.5g of dispersant hydroxypropylmethylcellulose, and 0.1g of wetting agent glycerol were weighed and uniformly stirred to obtain a coating slurry.
[0376] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coating was uniformly applied to both sides of a 7 μm polyethylene separator using an extrusion coating method to obtain a coated polyethylene separator.
[0377] (4) The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The separator was labeled as 7+2CP+2CP.
[0378] The form of the obtained modified composite polyethylene membrane coating is shown in Fig. 13.
[0379]
[0380] Example 3.4
[0381] Polyacrylonitrile (PAN) nanofiber / magnesium oxide coated polypropylene separator
[0382] (1) 8 g of polyacrylonitrile was dissolved in 92 g of N-methylpyrrolidone (NMP) and stirred to obtain a PAN solution with a mass concentration of 8% in this example. From this, PAN nanofibers were prepared using an electrospinning method.
[0383] (2) 5g of PAN nanofiber (average diameter of nanofiber: 400nm, aspect ratio in the range of 10 to 300) and 95g of magnesium oxide were weighed and dispersed in 240g of water, then stirred at high speed to obtain a PAN nanofiber / magnesium oxide dispersion. Subsequently, 5.0g of sodium carboxymethylcellulose was weighed and dissolved in 150g of water until completely dissolved. The two slurries above were mixed and uniformly stirred to obtain a coating slurry.
[0384] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated polypropylene membrane was obtained by uniformly coating both sides of a 12 μm polypropylene membrane using a microgravure coating method.
[0385] (4) The coated polypropylene separator was placed in a constant temperature oven to dry. The drying temperature was 60°C and the drying time was 1 hour. The thickness of the dried coating was 3 μm and the separator was labeled as 12+3CP+3CP.
[0386] The form of the obtained modified composite polypropylene membrane coating is shown in Fig. 4.
[0387]
[0388] Example 3.5
[0389] Polyimide / Silica Nanofiber / Li7La3Zr2O 12 (LLZO) Garnet-type solid oxide electrolyte-coated polyethylene separator
[0390] (1) 90 g of monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and added to the solvent N,N-dimethylformamide (DMF) to synthesize a polyamic acid solution with a mass concentration of 12% in this example. 10 g of TEOS was added and stirred uniformly. Polyamic acid nanofibers were prepared from this using an electrospinning method. The nanofibers were placed in a high-temperature furnace for imidization treatment. The heating program increased the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintained it at 300°C for 1 hour to obtain polyimide / silica nanofibers containing silica on the surface and inside of the fibers.
[0391] (2) 1 g of polyimide / silica nanofiber (average diameter of fiber: 350 nm, aspect ratio in the range of 15 to 450), 99 g of LLZO, 5 g of polyacrylamide, 1.8 g of surfactant perfluoroalkyl ether quaternary ammonium salt, 0.5 g of dispersant hydroxypropylmethylcellulose, 0.5 g of wetting agent glycerol, and 0.2 g of defoaming agent were dissolved in 140 g of water and stirred sufficiently to obtain a coating slurry.
[0392] (3) The stirred coating slurry was placed in a vacuum oven for 1 hour for defoaming. Afterwards, the slurry was uniformly coated on both sides of a 7 μm polyethylene separator using a microgravure coating method.
[0393] (4) The coated polyethylene separator was placed in a constant temperature oven to dry. The drying temperature was 55℃ and the drying time was 0.5 hours.
[0394] The form of the obtained modified composite polyethylene separator is shown in Fig. 15.
[0395]
[0396] Example 3.6
[0397] Polyimide nanofiber / boehmite-coated polyethylene composite separator
[0398] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10% in this example. PAA nanofibers were prepared from this using an electrospinning method. The temperature of the obtained fibers was raised from room temperature to 300°C at a heating rate of 5°C / min and maintained for 1 hour to obtain polyimide nanofibers.
[0399] (2) 20g of polyimide nanofiber (average diameter of nanofiber: 270nm, aspect ratio in the range of 10 to 280), 80g of boehmite (average particle size 500nm), 1.5g of sodium carboxymethylcellulose, 175g of a mixed solvent of water and ethanol (ethanol 5wt%), 0.3g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3g of a dispersant hydroxypropyl methylcellulose, and 0.06g of a wetting agent glycerol were weighed and uniformly stirred to obtain a coating slurry.
[0400] (3) After defoaming the stirred coating slurry by placing it in a vacuum oven for 1 hour, the coated and modified membrane was obtained by uniformly coating both sides of a 7 μm polyethylene membrane using a microgravure coating method.
[0401] (4) The coated and modified separator was placed in a constant temperature oven to dry. The drying temperature was 55°C and the drying time was 1 hour. The obtained modified composite polyethylene separator was denoted as 7+2CP+2CP.
[0402] The manufacturing process of Examples 3.7 to 3.8 was the same as Example 2.6, except that the inorganic particles used for the coating were different.
[0403] Example 3.9
[0404] Polyvinylidene fluoride (PVDF) nanofiber / boehmite-coated polyolefin composite separator
[0405] (1) PVDF was dissolved in the solvent N,N-dimethylacetamide (DMAc) to obtain a PVDF solution with a mass concentration of 8% in this example. From this, PVDF nanofibers were prepared using a blowing electrospinning method.
[0406] Steps (2) to (4) are the same as in Example 3.6.
[0407] Example 3.10
[0408] Polyimide hybrid nanofiber / barium titanate polyolefin composite separator
[0409] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a 1:1 molar ratio and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10% in this example. Nanobarium titanate (mass ratio of PAA to barium titanate 95:5) was added to this solution and thoroughly stirred. From this, PAA hybrid nanofibers were prepared using an electrospinning method. The obtained nanofibers were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it at 300°C for 1 hour to obtain polyimide / barium titanate hybrid nanofibers.
[0410] Steps (2) to (4) are the same as in Example 3.6, except that the inorganic particles are changed to barium titanate.
[0411] Example 3.11
[0412] Polyetherimide nanofiber / zinc oxide polyolefin composite separator (CP / PE / CP)
[0413] (1) 7.5 g of polyetherimide was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a polyetherimide solution with a mass concentration of 8% in this example. Polyetherimide nanofibers were prepared from this using a blowing spinning method.
[0414] Steps (2) to (4) are the same as in Example 3.6.
[0415] Example 3.12
[0416] Polyacrylonitrile (PAN) nanofiber / silica polyolefin composite membrane (CP / PE / CP)
[0417] (1) 7.5 g of polyacrylonitrile was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a PAN solution with a mass concentration of 7.5% in this example. Polyacrylonitrile nanofibers were prepared from this using a blowing spinning method.
[0418] Steps (2) to (4) are the same as in Example 3.6.
[0419] Example 3.13
[0420] P84 Nanofiber / Zirconia Polyolefin Composite Separator (CP / PE / CP)
[0421] (1) 7.5 g of P84 was dissolved in 92.5 g of N-methylpyrrolidone (NMP) and stirred to obtain a P84 solution with a mass concentration of 7.5% in this example. P84 nanofibers were prepared from this using a blowing spinning method.
[0422] Steps (2) to (4) are the same as in Example 3.6.
[0423] Example 3.14
[0424] Polyester (Polyethylene Terephthalate, PET) Nanofiber / Kaolin Polyolefin Composite Separator (CP / PE / CP)
[0425] (1) 7.5g of PET was dissolved in 92.5g of xylenol and stirred to obtain a PET solution with a mass concentration of 7.5% in this example. From this, PET nanofibers were prepared using a blowing spinning method.
[0426] Steps (2) to (4) are the same as in Example 3.6.
[0427] Example 3.15
[0428] Hydroxypropylmethylcellulose nanofiber / calcium silicate polyolefin composite separator (CP / PE / CP)
[0429] (1) 3.5 g of cellulose was dissolved in 96.5 g of xylenol and stirred to obtain a cellulose solution with a mass concentration of 3.5% in the example. Cellulose nanofibers were prepared from this using a blowing spinning method.
[0430] Steps (2) to (4) are the same as in Example 3.6.
[0431] The test results of the test performance of Examples 3.6 to 3.15 are shown in Table 13.
[0432]
[0433]
[0434] Example 3.16
[0435] Double-sided coated polyimide nanofiber / boemite polyolefin composite separator
[0436] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10% in this example. PAA nanofibers were prepared from this using an electrospinning method. The fibers were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide nanofibers.
[0437] (2) 0.4g of polyimide nanofiber, 99.6g of boehmite (average particle size 500 nm), 1.5g of sodium carboxymethylcellulose, 175g of a mixed solvent of water and ethanol (ethanol 5 wt%), 0.3g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3g of a dispersant hydroxypropyl methylcellulose, and 0.06g of a wetting agent glycerol were weighed and thoroughly stirred to obtain a coating slurry.
[0438] (3) After defoaming the coating slurry by placing it in a vacuum oven for 1 hour, the coating was uniformly coated on both sides of a 9 μm polyethylene membrane using a microgravure coating method to obtain a coated and modified membrane. After drying, the thickness of the coating layer was 2 μm.
[0439] (4) The coated and modified membranes were placed in a constant temperature oven to dry. The drying temperature was 55°C and the drying time was 1 hour. The obtained modified composite membranes were each labeled as 9+2CP+2CP. The thickness of the modified composite polyethylene membranes is 13 μm.
[0440] The manufacturing process of Examples 3.17 to 3.24 and Comparative Example 1 (3.C1) and Comparative Example 2 (3.C2) was identical to Example 3.16, except that the amounts of polyimide nanofibers and boehmite were different. Specific compositions and test results are shown in Table 14.
[0441]
[0442] Example 4.1
[0443] Double-sided coated polyimide nanofiber / boemite polyolefin composite separator
[0444] (1) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a polyamic acid solution with a mass concentration of 10% in this example. PAA nanofibers were prepared from this using an electrospinning method. The fibers were imidized in a high-temperature furnace. The heating program was to increase the temperature from room temperature to 300°C at a heating rate of 5°C / min and maintain it for 1 hour to obtain polyimide nanofibers.
[0445] (2) Monomer pyromellitic acid dianhydride (PMDA) and monomer 4,4'-diaminodiphenyl ether (ODA) were weighed in a molar ratio of 1:1 and reacted in the solvent N,N-dimethylformamide (DMF) to obtain a clear and transparent polyamic acid solution with a mass concentration of 10%. PAA microspheres were prepared from this using an electrostatic blowing method. The temperature of the obtained microspheres was raised from room temperature to 300°C at a heating rate of 5°C / min and maintained for 1 hour to obtain polyimide microspheres.
[0446] (3) 35g of polyimide microspheres (average particle size of microspheres: 750nm), 5.4g of polyimide nanofibers, 59.6g of silica (average particle size 500nm), 1.5g of sodium carboxymethylcellulose, 175g of a mixed solvent of water and ethanol (ethanol 5wt%), 0.3g of a surfactant perfluoroalkyl ether quaternary ammonium salt, 0.3g of a dispersant hydroxypropyl methylcellulose, and 0.06g of a wetting agent glycerol were weighed and thoroughly stirred to obtain a coating slurry.
[0447] (4) After defoaming the coating slurry by placing it in a vacuum oven for 1 hour, the coating was uniformly coated on both sides of a 7 μm polyethylene membrane using a microgravure coating method to obtain a coated and modified membrane. After drying, the thickness of the coating layer was 2 μm.
[0448] (5) The coated and modified membrane was placed in a constant temperature oven to dry. The drying temperature was 55°C and the drying time was 1 hour. The obtained modified composite polyethylene membrane was designated as 7+2CP+2CP. The thickness of the modified composite polyethylene membrane was 11 μm. The results of the performance test are shown in Table 15.
[0449]
Claims
Claim 1 A method for manufacturing a coated and modified composite separator, wherein the coated and modified composite separator comprises a base membrane and a coating layer, wherein the coating layer is coated on any one or both sides of the base membrane, and wherein the coating layer comprises at least two of b2.1 high temperature resistant polymer microspheres, b2.2 high temperature resistant polymer nanofibers, and b2.3 inorganic particles, and the method comprises the following steps: (1) providing a coating slurry comprising a slurry solvent and at least two of the following components: b2.1 high temperature resistant polymer microspheres, b2.2 high temperature resistant polymer nanofibers, and b2.3 inorganic particles; and (2) a step of coating the coating slurry on one or both sides of a base film; wherein the coating slurry comprises high-temperature resistant polymer microspheres and high-temperature resistant polymer nanofibers, and the high-temperature resistant polymer is polyimide, and the manufacturing method is characterized by comprising the following steps: A: using a dianhydride and a diamine as monomers, and having an intrinsic viscosity of 0.A: a step of preparing a polyamic acid solution by low-temperature condensation polymerization in a polar aprotic solvent controlled to 0.1 to 1 dL / g; and a step of preparing a polyamic acid material having a nanofiber / microsphere composite form using a template method, spray drying technology, electrospinning technology, blowing spinning technology, or blowing-assisted electrospinning; B: a step of thermally imidizing the polyamic acid material prepared in Step A by high-temperature heat treatment to form a polyimide material; C: a step of formulating a coating slurry, comprising the steps of dispersing the polyimide material prepared in Step B in a dispersion and stirring uniformly, and adding a binder to the polyimide dispersion and stirring uniformly at a stirring speed of 500 to 30,000 rpm; D: a step of uniformly applying the coating slurry obtained in Step C to the surface of a base film; and E: A step of drying the composite separation membrane obtained through the treatment of step D, wherein the drying temperature is 50 to 100℃ and the drying time is 0.1 min to 12 hours. Claim 2 In claim 1, for the polyamic acid solution used in step A, the dianhydride is one or a mixture of two or more of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (α-BPDA), 4,4'-diphenyl ether dianhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), hexafluorodianhydride (6FDA), bisphenol A diether anhydride (BPADA), and 3,3,4,4-diphenylsulfone tetracarboxylic acid dianhydride (DSDA), and the diamine is 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), It is one or a mixture of two or more of 3,4'-diaminodiphenylmethane (3,4'-MDA), 4,4'-diaminodiphenylmethane (4,4'-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB), 2,2'-bis(trifluoromethyl)-4,4'-diaminophenyl ether (6FODA), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP); or prepared by mixing at least two polyamic acid solutions; The solid content of the above polyamic acid solution is 5 to 40 wt%, and / or, the thermal imidization process used in step B has a maximum temperature of 250 to 450°C and a residence time of 0.A method for manufacturing, characterized in that the time is 1 to 30 minutes and / or, the binder of step C is one or more of aqueous PVDF emulsion, polyvinyl alcohol, polyethylene oxide, acrylic water-soluble adhesive, styrene-butadiene rubber, sodium carboxymethylcellulose, and polyvinylpyrrolidone; the weight parts of each component of the coating slurry are 1 to 3 weight parts of binder, 89 to 52 weight parts of solvent, and 10 to 45 weight parts of polyimide; the dispersion is water and / or, in step D, one or both sides of a polyolefin separator are coated with polyimide, and the coating method is one of electrostatic spraying, blade coating, extrusion coating, wire coating, transfer coating, dip coating, gravure, or micro-gravure coating. Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete Claim 21 delete Claim 22 delete Claim 23 delete Claim 24 delete Claim 25 delete Claim 26 delete Claim 27 delete Claim 28 delete Claim 29 delete Claim 30 delete Claim 31 delete Claim 32 delete Claim 33 delete
Citation Information
Patent Citations
Water soluble binder composition, and Electrode for a rechargeable battery employing the same
KR1020130112324A
Separator for nonaqueous secondary battery, and nonaqueous secondary battery
JP2010146839A
Inorganic polymer two-layered separator for secondary cell with improved heat-resisting property and method of manufacturing same
KR101419772B1