Hierarchical porous zeolites, methods of making and using the same, ceramic composite separators, methods of making and using the same, and lithium ion batteries

Abstract

The application provides a kind of multi-level hole zeolite and its preparation method and application, ceramic composite diaphragm and its preparation method and lithium ion battery, it is related to battery technical field.The preparation method of multi-level hole zeolite provided by the application comprises: mixing mesoporous silica particles and tetrapropylammonium hydroxide solution, after drying, steam assisted conversion reaction is carried out in reaction kettle, after reaction is finished, multi-level hole zeolite is obtained;The temperature of steam assisted conversion reaction is 90-175 DEG C, and the time is 48-96h;Multi-level hole zeolite has microporous and through hole structure, the pore size of microporous is 0.3-1nm;The pore size of through hole is 300-500nm.The preparation method of multi-level hole zeolite provided by the application is simple and convenient, and the multi-level hole zeolite prepared presents multi-level hole structure, there are a large number of through holes on the particle, for preparing battery diaphragm, can effectively increase the wettability of diaphragm, reduce the internal resistance of diaphragm, improve ion conductivity and the energy density of battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a multi-level porous zeolite and its preparation method and application, a ceramic composite separator and its preparation method, and a lithium-ion battery. Background Technology

[0002] The separator is one of the four essential materials in lithium-ion batteries. Its main function is to prevent short circuits caused by direct contact between the positive and negative electrodes, while allowing ions in the electrolyte to pass freely. The performance of the separator determines the battery's internal resistance and interface structure, directly affecting its electrochemical performance and safety. A high-performance separator has a significant impact on improving the overall performance of lithium-ion batteries.

[0003] Current commercial membranes, such as PP membranes, PE membranes, and PP / PE / PP three-layer composite membranes or PE / ceramic membranes, all suffer from problems such as poor wettability, low puncture strength, and high electrochemical reaction resistance.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The first objective of this invention is to provide a method for preparing multi-level porous zeolite to solve at least one of the above-mentioned problems.

[0006] A second objective of this invention is to provide a multi-level porous zeolite.

[0007] A third objective of this invention is to provide the application of the above-mentioned hierarchical porous zeolite in the preparation of battery separators.

[0008] The fourth objective of this invention is to provide a ceramic composite diaphragm to overcome the problems of poor wettability, low puncture strength, and high electrochemical reaction impedance of the base membrane.

[0009] The fifth objective of this invention is to provide a method for preparing the above-mentioned ceramic composite diaphragm.

[0010] The sixth objective of this invention is to provide a lithium-ion battery.

[0011] In a first aspect, the present invention provides a method for preparing hierarchical porous zeolite, comprising the following steps:

[0012] Mesoporous silica particles and tetrapropylammonium hydroxide solution were mixed, dried, and then subjected to a steam-assisted conversion reaction in a reactor. After the reaction was completed, multi-level porous zeolite was obtained.

[0013] The temperature of the steam-assisted conversion reaction is 90-175℃, and the time is 48-96h;

[0014] The multi-level porous zeolite has a through-pore structure with a pore diameter of 300-800 nm.

[0015] As a further technical solution, the particle size of the mesoporous silica particles is 0.3-1.5μm, preferably 0.5-1.0μm;

[0016] The mesoporous silica particles have a pore size of 500-600 nm.

[0017] As a further technical solution, the molar ratio of silica to tetrapropylammonium hydroxide in the mesoporous silica particles is 1:0.05-0.50, preferably 1:0.15-0.20;

[0018] And / or, the mass ratio of tetrapropylammonium hydroxide to water in the tetrapropylammonium hydroxide solution is 1:1.0-5.0, preferably 1:1.5-3.5.

[0019] Secondly, the present invention provides a hierarchical porous zeolite, which is prepared by the above-described preparation method;

[0020] Preferably, the particle size of the multi-level porous zeolite is 0.5-5 μm, and more preferably 1-3 μm.

[0021] Thirdly, the present invention provides the application of the above-mentioned hierarchical porous zeolite in the preparation of battery separators.

[0022] Fourthly, the present invention provides a ceramic composite diaphragm, comprising a base membrane, wherein at least one side of the base membrane is provided with a coating;

[0023] The coating comprises, by weight parts: 40-75 parts of the above-mentioned multi-porous zeolite, 15-30 parts of thickener, 0.1-10 parts of binder, 0.1-5 parts of dispersant and 0.1-5 parts of leveling agent.

[0024] As a further technical solution, the coating comprises, by weight parts: 60-75 parts of the above-mentioned multi-porous zeolite, 20-25 parts of thickener, 1-5 parts of binder, 2-5 parts of dispersant and 1-3 parts of leveling agent.

[0025] As a further technical solution, the dispersant includes at least one of polyvinyl alcohol, polyacrylamide, hexadecylbenzene sulfonic acid, polyethylene glycol, modified polyacrylic acid, carboxylated modified styrene-butadiene latex, polyacrylonitrile modified copolymer, polyacrylamide, polyvinylacetamide, ammonium polyacrylate, polyether derivatives, and polycarboxylate.

[0026] And / or, the thickener includes at least one of carboxymethyl cellulose, hydroxymethyl cellulose, bentonite, and attapulgite clay;

[0027] And / or, the adhesive includes at least one of acrylic polymers and polyurethane adhesives;

[0028] And / or, the base film includes at least one of polyethylene, polypropylene, polypropylene / polyethylene / polypropylene three-layer composite film, polyimide, polyvinylidene fluoride or nonwoven fabric;

[0029] And / or, the thickness of the base film is 5-20 μm and the porosity is 20%-70%;

[0030] And / or, the thickness of the coating is 1-5 μm.

[0031] Fifthly, the present invention provides a method for preparing the above-mentioned ceramic composite diaphragm, comprising: mixing multi-porous zeolite, dispersant and water to obtain solution A; mixing thickener, binder, leveling agent and water to obtain solution B; mixing solution A and solution B, and then coating them onto at least one side of a base membrane, and drying them to obtain the ceramic composite diaphragm.

[0032] In a sixth aspect, the present invention provides a lithium-ion battery using the above-mentioned ceramic composite separator as the separator.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a method for preparing hierarchical porous zeolite using mesoporous silica particles as templates and employing a steam-assisted conversion method. This method is simple and convenient, and the prepared hierarchical porous zeolite exhibits a hierarchical porous structure with numerous through-pores on the particles. When used to prepare battery separators, it can effectively increase the wettability of the separator, promote electrolyte absorption, reduce the internal resistance of the separator, and alleviate the phenomenon of central black spots and edge expansion during battery cycling. At the same time, the through-pores on the hierarchical porous zeolite can reduce the permeation resistance of the electrolyte, shorten the permeation path, thereby improving ionic conductivity and weakening electrochemical impedance. The presence of hierarchical pores can increase the electrolyte retention capacity of the separator, thereby improving the energy density of the battery. In addition, the hierarchical porous zeolite can maintain the inherent thermal stability and puncture resistance of the separator. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 Electron micrograph (50000X) of a multi-level porous zeolite provided in Embodiment 1 of the present invention;

[0037] Figure 2 Electron micrograph (20000X) of a multi-level porous zeolite provided in Embodiment 1 of the present invention;

[0038] Figure 3 Electron micrograph (5000X) of a multi-level porous zeolite provided in Embodiment 1 of the present invention;

[0039] Figure 4 This is a conventional porous zeolite electron microscope image (5000X) of the present invention. Detailed Implementation

[0040] The embodiments and examples of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments and examples are for illustrative purposes only and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0041] In a first aspect, the present invention provides a method for preparing hierarchical porous zeolite, comprising the following steps:

[0042] Mesoporous silica particles and tetrapropylammonium hydroxide solution were mixed, dried, and then subjected to a steam-assisted conversion reaction in a reactor. After the reaction was completed, multi-level porous zeolite was obtained.

[0043] The temperature of the steam-assisted conversion reaction can be, for example, but not limited to, 90°C, 110°C, 130°C, 150°C, or 175°C, and the time can be, for example, but not limited to, 48h, 60h, 72h, 84h, or 96h. The pore size of the multi-level porous zeolite can be adjusted by regulating the temperature and time of the steam-assisted conversion reaction.

[0044] The hierarchical porous zeolite has a microporous and through-pore structure. The pore size of the micropores is about 0.3-1 nm (common zeolite micropores); the pore size of the through-pores is 300-800 nm.

[0045] The method for preparing hierarchical porous zeolite provided by this invention uses mesoporous silica particles as templates and employs a steam-assisted conversion method to prepare hierarchical porous zeolite. Crystallization synthesis is carried out under high temperature and high pressure conditions, and TPA is used during the crystallization process. + Ions bind to the surface of mesoporous silica particles to form a framework, OH - Ions enter the mesopores and etch the mesoporous silica from the inside to obtain hierarchical porous zeolite.

[0046] This preparation method is simple and convenient. The resulting hierarchical porous zeolite exhibits a hierarchical porous structure with numerous through-pores on the particles. When used to prepare battery separators, it effectively increases the wettability of the separator, promotes electrolyte absorption, reduces the internal resistance of the separator, and alleviates the phenomenon of central black spots and edge expansion during battery cycling. At the same time, the through-pores on the hierarchical porous zeolite can reduce the permeation resistance of the electrolyte, shorten the permeation path, thereby improving ionic conductivity and weakening electrochemical impedance. The presence of hierarchical pores can increase the electrolyte retention capacity of the separator, thereby improving the energy density of the battery. In addition, the hierarchical porous zeolite can maintain the inherent thermal stability and puncture resistance of the ceramic coating.

[0047] In some optional embodiments, the particle size of the mesoporous silica particles may be, for example, but not limited to, 0.3 μm, 0.6 μm, 0.9 μm, 1.2 μm or 1.5 μm, preferably 0.5-1.0 μm;

[0048] The mesoporous silica particles have a pore size of 500-600 nm.

[0049] In some optional embodiments, the molar ratio of silica to tetrapropylammonium hydroxide in the mesoporous silica particles can be, for example, but not limited to, 1:0.05, 1:0.10, 1:0.20, 1:0.30, 1:0.40 or 1:0.50, preferably 1:0.15-0.20;

[0050] And / or, the mass ratio of tetrapropylammonium hydroxide to water in the tetrapropylammonium hydroxide solution can be, for example, but not limited to, 1:1.0, 1:2.0, 1:3.0, 1:4.0 or 1:5.0, preferably 1:1.5-3.5.

[0051] In some alternative embodiments, the drying time is 5-36 hours, preferably 12-24 hours.

[0052] Secondly, the present invention provides a multi-level porous zeolite, which is prepared by the above-described preparation method.

[0053] The multi-level porous zeolite provided in this invention has a microporous and through-pore structure, which can effectively reduce electrolyte permeation resistance when used in battery separators.

[0054] In some alternative embodiments, the particle size of the hierarchical porous zeolite may be, for example, but not limited to, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, preferably 1-3 μm.

[0055] Thirdly, the present invention provides the application of the above-mentioned hierarchical porous zeolite in the preparation of battery separators.

[0056] The hierarchical porous zeolite provided by this invention exhibits a hierarchical porous structure with numerous through-pores on the particles. When used to prepare battery separators, it can effectively increase the wettability of the separator, promote electrolyte absorption, reduce the internal resistance of the separator, and alleviate the phenomenon of central black spots and edge expansion during battery cycling. At the same time, the through-pores on the hierarchical porous zeolite can reduce the permeation resistance of the electrolyte, shorten the permeation path, thereby improving ionic conductivity and weakening electrochemical impedance. The presence of hierarchical pores can increase the electrolyte retention capacity of the separator, thereby improving the energy density of the battery. In addition, the hierarchical porous zeolite can maintain the inherent thermal stability and puncture resistance of the separator.

[0057] Fourthly, the present invention provides a ceramic composite diaphragm, comprising a base membrane, wherein at least one side of the base membrane is provided with a coating;

[0058] The coating is mainly prepared from the above-mentioned hierarchical porous zeolite, thickener, binder, dispersant and leveling agent. By mass fraction, the mass fraction of hierarchical porous zeolite in the coating can be, for example, but not limited to, 40, 50, 60, 70 or 75 parts, preferably 60-75 parts; the mass fraction of thickener can be, for example, but not limited to, 15, 20, 25 or 30 parts, preferably 20-25 parts; the mass fraction of binder can be, for example, but not limited to, 0.1, 1, 2, 4, 6, 8 or 10 parts, preferably 1-5 parts; the mass fraction of dispersant can be, for example, but not limited to, 0.1, 1, 2, 3, 4 or 5 parts, preferably 2-5 parts; the mass fraction of leveling agent can be, for example, but not limited to, 0.1, 1, 2, 3, 4 or 5 parts, preferably 1-3 parts.

[0059] Further optimization and adjustment of the various components in the coating resulted in a better ceramic composite diaphragm.

[0060] In some optional embodiments, the dispersant includes, but is not limited to, at least one of polyvinyl alcohol, polyacrylamide, cetylbenzenesulfonic acid, polyethylene glycol, modified polyacrylic acid, carboxylated modified styrene-butadiene latex, polyacrylonitrile modified copolymer, polyacrylamide, polyvinylacetamide, ammonium polyacrylate, polyether derivatives, and polycarboxylates.

[0061] And / or, the thickener includes, but is not limited to, at least one of carboxymethyl cellulose, hydroxymethyl cellulose, bentonite, and attapulgite clay;

[0062] And / or, the adhesive includes, but is not limited to, at least one of acrylic polymers and polyurethane adhesives;

[0063] And / or, the base film includes, but is not limited to, at least one of polyethylene, polypropylene, polypropylene / polyethylene / polypropylene three-layer composite film, polyimide, polyvinylidene fluoride or nonwoven fabric;

[0064] And / or, the thickness of the base film may be, for example, but not limited to, 5 μm, 10 μm, 15 μm or 20 μm, and the porosity may be, for example, but not limited to, 20%, 30%, 40%, 50%, 60% or 70%;

[0065] And / or, the thickness of the coating may be, for example, but not limited to, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm.

[0066] Fifthly, the present invention provides a method for preparing the above-mentioned ceramic composite diaphragm, comprising: mixing multi-porous zeolite, dispersant and water to obtain solution A; mixing thickener, binder, leveling agent and water to obtain solution B; mixing solution A and solution B, and then coating them onto at least one side of a base membrane, and drying them to obtain the ceramic composite diaphragm.

[0067] The method for preparing the ceramic composite diaphragm provided by this invention is simple and convenient, and the prepared diaphragm is uniform and has good stability.

[0068] In a sixth aspect, the present invention provides a lithium-ion battery using the above-mentioned ceramic composite separator as the separator.

[0069] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0070] Example 1

[0071] A multi-level porous zeolite is prepared by the following method:

[0072] Mesoporous silica particles (MSPs) with a particle size of 500 nm and a pore size of 500-600 nm were mixed in an aqueous solution of tetrapropylammonium hydroxide (TPAOH) and ultrasonically mixed to ensure homogeneity. The molar ratio of MSPs to TPAOH was 1:0.2; the mass ratio of tetrapropylammonium hydroxide to water in the tetrapropylammonium hydroxide solution was 1:2.5. The mixture was dried at room temperature for 24 hours to obtain a white powder. This white powder was poured into a polytetrafluoroethylene (PTFE) container, and the container containing the MSPs and TPAOH powder was placed in a reaction vessel. 30 g of deionized water was added to the bottom of the vessel (the PTFE container containing the powder mixture was positioned above the liquid surface, without contacting the deionized water). The sealed reaction vessel was then placed in a 100°C oven for crystallization for 68 hours. White powder was collected from within a polytetrafluoroethylene (PTFE) support, centrifuged and washed until neutral, dried at 60°C for 12 hours, and then calcined at 600°C for 5 hours in a muffle furnace to obtain hierarchical porous zeolite. The resulting MFI zeolite particles had a particle size of 1.5 μm, with macropores on the surface approximately 400 nm in diameter and micropores of 0.5 nm in diameter inside. Electron microscopy images are shown below. Figures 1-3 As shown.

[0073] Example 2

[0074] A battery separator, prepared by the following method:

[0075] Add 71 parts by weight of the multi-porous MFI zeolite powder provided in Example 1 to 60 parts by weight of water, and disperse by mechanical stirring for 12 hours. Then add 3.1 parts by weight of polyvinyl alcohol and stir mechanically at 800 rpm for 4 hours to obtain a suspension. Add 20 parts by weight of thickener (hydroxymethyl cellulose), 5 parts by weight of binder (polyurethane and polyacrylic acid), and 1 part by weight of leveling agent (polyacrylic acid) to 18 parts by weight of water, and stir mechanically at 500 rpm for 3 hours. Add the suspension to the mixture and stir mechanically at 800 rpm for 2.5 hours to disperse evenly and obtain a ceramic coating slurry. Then roll-coat the mixed ceramic slurry onto both sides of a ceramic diaphragm with a thickness of 9 μm, resulting in a coating thickness of 2 μm. After drying, the ceramic composite diaphragm is obtained. Studies have shown that the liquid absorption time of this ceramic composite separator is 0.185 cm / s, and the ionic conductivity is 1.85. Furthermore, the use of this separator in battery fabrication reduces the battery's internal resistance, EIS ohmic impedance, and charge transfer impedance (compared to ordinary AL2O3 ceramic separators). At the same time, it increases the battery's liquid retention capacity, extends its cycle life, and alleviates the phenomenon of central black spots and edge expansion during battery cycling.

[0076] Example 3

[0077] A multi-level porous zeolite is prepared by the following method:

[0078] Mesoporous silica particles (MSPs) with a particle size of 1500 nm and a pore size of 500-600 nm were mixed in an aqueous solution of tetrapropylammonium hydroxide (TPAOH) and ultrasonically mixed to ensure homogeneity. The molar ratio of MSPs to TPAOH was 1:0.5; the mass ratio of TPAOH to water in the TPAOH solution was 1:5. The mixture was dried at room temperature for 24 hours to obtain a white powder. This white powder was poured into a polytetrafluoroethylene (PTFE) container, and the container containing the MSPs and TPAOH powder was placed in a reaction vessel. 30 g of deionized water was added to the bottom of the vessel (the PTFE container containing the powder mixture was positioned above the liquid surface, without contacting the deionized water). The sealed reaction vessel was then placed in a 90°C oven for crystallization for 96 hours. White powder was collected from within a polytetrafluoroethylene (PTFE) support, centrifuged and washed until neutral, dried at 60°C for 12 hours, and then calcined at 600°C for 5 hours in a muffle furnace to obtain hierarchical porous zeolite. MFI zeolite particles with a hierarchical porous structure were obtained. The zeolite particles had a diameter of 2 μm, with macropores on their surface having a diameter of approximately 750-800 nm, and micropores with a diameter of 0.5 nm present internally.

[0079] Example 4

[0080] A battery separator, prepared by the following method:

[0081] Add 40 parts by weight of the multi-porous MFI zeolite powder provided in Example 3 to 60 parts by weight of water, and disperse by mechanical stirring for 12 hours. Then add 0.1 parts by weight of polyvinyl alcohol and stir mechanically at 800 rpm for 4 hours to obtain a suspension. Next, add 15 parts by weight of thickener (hydroxymethyl cellulose), 10 parts by weight of binder (polyurethane and polyacrylic acid), and 5 parts by weight of leveling agent (polyacrylic acid) to 18 parts by weight of water, and stir mechanically at 600 rpm for 3 hours. Add the suspension to the mixture and stir mechanically at 1000 rpm for 2.5 hours to disperse evenly and obtain a ceramic coating slurry. Then, roll-coat the mixed ceramic slurry onto both sides of a 9 μm thick ceramic diaphragm, resulting in a coating thickness of 2 μm. After drying, the ceramic composite diaphragm is obtained. Studies have shown that the liquid absorption time of this ceramic composite diaphragm is 0.17 cm / s, and the ionic conductivity is 1.70.

[0082] Example 5

[0083] A multi-level porous zeolite is prepared by the following method:

[0084] Mesoporous silica particles (MSPs) with a particle size of 300 nm and a pore size of 500-600 nm were mixed in an aqueous solution of tetrapropylammonium hydroxide (TPAOH) and ultrasonically mixed to ensure homogeneity. The molar ratio of MSPs to TPAOH was 1:0.05; the mass ratio of TPAOH to water in the TPAOH solution was 1:1.5. The mixture was dried at room temperature for 24 hours to obtain a white powder. This white powder was poured into a polytetrafluoroethylene (PTFE) container, and the container containing the MSPs and TPAOH powder was placed in a reaction vessel. 30 g of deionized water was added to the bottom of the vessel (the PTFE container containing the powder mixture was positioned above the liquid surface, without contacting the deionized water). The sealed reaction vessel was then placed in a 170°C oven for crystallization for 50 hours. White powder was collected from within a polytetrafluoroethylene (PTFE) support, centrifuged and washed until neutral, dried at 60°C for 12 hours, and then calcined in a muffle furnace at 600°C for 5 hours to obtain hierarchical porous zeolite. MFI zeolite particles with a hierarchical porous structure were obtained. The zeolite particles had a diameter of 1.2 μm, with macropores on their surface having a diameter of approximately 300-350 nm, and micropores with a diameter of 0.5 nm inside.

[0085] Example 6

[0086] A battery separator, prepared by the following method:

[0087] Add 70 parts by weight of the multi-porous MFI zeolite powder provided in Example 5 to 60 parts by weight of water, and disperse by mechanical stirring for 12 hours. Then add 5 parts by weight of polyvinyl alcohol and stir mechanically at 800 rpm for 4 hours to obtain a suspension. Add 30 parts by weight of thickener (hydroxymethyl cellulose), 2 parts by weight of binder (polyurethane and polyacrylic acid), and 0.1 parts by weight of leveling agent (polyacrylic acid) to 18 parts by weight of water, and stir mechanically at 500 rpm for 3 hours. Add the suspension to the mixture and stir mechanically at 800 rpm for 2.5 hours to disperse evenly and obtain a ceramic coating slurry. Then roll-coat the mixed ceramic slurry onto both sides of a ceramic diaphragm with a thickness of 9 μm, resulting in a coating thickness of 2 μm. After drying, the ceramic composite diaphragm is obtained. Studies have shown that the liquid absorption time of this ceramic composite diaphragm is 0.17 cm / s, and the ionic conductivity is 1.70.

[0088] Comparative Example 1

[0089] Add 71 parts by weight of commercially available conventional MFI zeolite powder (particle size 1.5 μm, no through-pores) to 60 parts by weight of the first part of water. Figure 4As shown, after mechanically dispersing for 12 hours, 3.1 parts by weight of polyvinyl alcohol were added, and the mixture was mechanically stirred at 800 rpm for 4 hours to obtain a suspension. Then, 20 parts by weight of hydroxymethyl cellulose, 5 parts by weight of polyurethane, and 1 part by weight of polyacrylic acid were added to 18 parts by weight of a second part of water, and the mixture was mechanically stirred at 500 rpm for 3 hours. The suspension was then added to this mixture, and the mixture was mechanically stirred at 800 rpm for 2.5 hours to disperse evenly, resulting in a ceramic coating slurry. The mixed ceramic slurry was then roller-coated onto both sides of a 9 μm thick ceramic diaphragm, resulting in a coating thickness of 2 μm. After drying, the ceramic composite diaphragm was obtained.

[0090] Comparative Example 2

[0091] A hierarchical porous zeolite, which differs from Example 1 in that the pore size of the through-pores of the prepared hierarchical porous zeolite is 1200 nm and the particle size is 2 μm.

[0092] The preparation method is as follows: Mesoporous silica particles (MSPs) with a particle size of 2000 nm were mixed in an aqueous solution of tetrapropylammonium hydroxide (TPAOH), and the mixture was ultrasonically stirred to ensure uniform mixing. The molar ratio of MSPs to TPAOH was 1:0.2; the mass ratio of tetrapropylammonium hydroxide to water in the tetrapropylammonium hydroxide solution was 1:2.5. The mixture was dried at room temperature for 24 hours to obtain a white powder. This white powder was poured into a polytetrafluoroethylene (PTFE) container, and the container containing the MSPs and TPAOH powder was placed in a reaction vessel. 30 g of deionized water was added to the bottom of the vessel (the PTFE container containing the powder mixture was positioned above the liquid surface, without contact with the deionized water). The sealed reaction vessel was then placed in a 100°C oven for crystallization for 73 hours. The white powder was collected from the PTFE support, centrifuged and washed until neutral, and dried at 60°C for 12 hours. Subsequently, it was calcined in a muffle furnace at 600°C for 5 hours to obtain a hierarchical porous zeolite. MFI zeolite particles with a hierarchical porous structure were obtained. The MFI particle size was 1.5 μm, the through-pores on its surface had a diameter of about 1200 nm, and there were micropores with a diameter of 0.5 nm inside.

[0093] Comparative Example 3

[0094] A hierarchical porous zeolite, which differs from Example 1 in that the pore size of the through-pores of the prepared hierarchical porous zeolite is 200 nm and the particle size is 0.25 μm.

[0095] The preparation method is as follows: Mesoporous silica particles (MSPs) with a particle size of 250 nm were mixed in an aqueous solution of tetrapropylammonium hydroxide (TPAOH), and the mixture was ultrasonically stirred until homogeneous. The molar ratio of MSPs to TPAOH was 1:0.2; the mass ratio of tetrapropylammonium hydroxide to water in the tetrapropylammonium hydroxide solution was 1:2.5. The mixture was dried at room temperature for 24 hours to obtain a white powder. This white powder was poured into a polytetrafluoroethylene (PTFE) container, and the container containing the MSPs and TPAOH powder was placed in a reaction vessel. 30 g of deionized water was added to the bottom of the vessel (the PTFE container containing the powder mixture was positioned above the liquid surface, without contact with the deionized water). The sealed reaction vessel was then placed in a 100°C oven for crystallization for 60 hours. The white powder was collected from the PTFE support, centrifuged and washed until neutral, and dried at 60°C for 12 hours. Subsequently, it was calcined in a muffle furnace at 600°C for 5 hours to obtain a hierarchical porous zeolite. MFI zeolite particles with a hierarchical porous structure were obtained. The MFI particle size was 1 μm, the through-pores on its surface had a diameter of about 200 nm, and there were micropores with a diameter of 0.5 nm inside.

[0096] Comparative Example 4

[0097] A multi-level porous zeolite differs from Example 1 in that it is prepared by direct heating instead of steam-assisted conversion reaction.

[0098] The preparation method is as follows: Aluminum powder, distilled water, and sodium hydroxide were mixed evenly under vigorous stirring. Then, tetrapropylammonium aqueous solution (TPAOH) and silica sol were added to prepare aluminosilicate gel. The final molar composition of the synthesized mixture was 24.5SiO2:0.5Al2O3:0.5Na2O:9.8TPAOH:780H2O. After complete mixing, the resulting mixture was placed in a stainless steel autoclave. Hydrothermal synthesis was performed at 100℃ for 50 hours to obtain the sample. The obtained sample was centrifuged, washed repeatedly with distilled water, and dried at 100℃ for 10 hours to obtain a white powder sample, which was a conventional MFI zeolite without a hierarchical porous structure.

[0099] Experimental Example 1

[0100] The diaphragms prepared by the zeolites provided in Comparative Examples 2-4 according to the preparation method of Example 2 were then tested for ionic conductivity and liquid absorption rate.

[0101] (1) Ionic conductivity test: In an environment of 25℃, a symmetrical battery that has been left to stand at room temperature is clamped with two stainless steel electrodes of different sizes and clamps to ensure close contact between the stainless steel electrodes in the symmetrical battery. Before the test, the clamps are loosened and tightened 6 times to remove air bubbles between the separator and the stainless steel electrodes. Then, the symmetrical battery is placed vertically, and the AC impedance of the symmetrical battery is tested using an electrochemical workstation. The resistance of symmetrical batteries with 1, 2, 3, 4 and 5 separators is measured respectively. Each symmetrical battery is tested 3 times and the average value is calculated. A curve of the resistance of the symmetrical battery versus the number of separator layers is plotted, and a linear relationship y=kx+b is fitted. The correlation coefficient R: the slope k value is the separator resistance R, unit: Ω;

[0102] Measurement accuracy requirements: The resistance difference in the symmetrical battery in 3 tests should be <0.020 μm; otherwise, it needs to be retested (the number of retests should generally not exceed 3 times) until the requirement is met; in addition, the correlation coefficient R should be ≥0.98; otherwise, the symmetrical battery needs to be remade for testing.

[0103] The formula for calculating the surface resistance of the diaphragm is RA = Rs * A; where RA is the surface resistance of the diaphragm, in Ω·cm. 2 RS is the membrane resistance in Ω, and A is the effective area of ​​the membrane in a symmetrical battery, taken as 6cm². 2 ;

[0104] Calculation of membrane ionic conductivity:

[0105] The formula for calculating the ionic conductivity of the membrane is: σs=d / (Rs*A*10); where σs is the ionic conductivity of the membrane, in mS / cm; d is the thickness of the membrane, in μm, measured by a thickness gauge; and Rs is the membrane resistance, in Ω.

[0106] (2) Liquid absorption rate test: Cut the diaphragm into a 15mm wide strip, suspend it horizontally on the sample holder, and fix it at both ends with clips. There should be no wrinkles. Use a pipette to draw 5ul of electrolyte and drop it onto the diaphragm until the electrolyte is completely absorbed. Record the time t (s) and the electrolyte diffusion length L (cm). Calculate the liquid absorption rate V = L / s.

[0107] The results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ceramic composite separator, characterized by, The base film is provided with a coating on at least one side thereof; The coating comprises, in parts by mass, 40-75 parts of the hierarchical zeolite, 15-30 parts of the thickening agent, 0.1-10 parts of the binder, 0.1-5 parts of the dispersant, and 0.1-5 parts of the leveling agent; The method for preparing the hierarchical zeolite comprises the following steps: The mesoporous silica particles and a solution of tetrapropylammonium hydroxide are mixed, and after drying, a steam-assisted conversion reaction is performed in a reaction kettle, and after the reaction is completed, the hierarchical zeolite is obtained; The steam-assisted conversion reaction is performed at a temperature of 90-175℃ for 48-96h; The hierarchical zeolite has a through-pore structure, and the through-pores have a pore size of 300-800nm; The mesoporous silica particles have a particle size of 0.5-1.0μm; The molar ratio of silica to tetrapropylammonium hydroxide in the mesoporous silica particles is 1:0.15-0.20; The mass ratio of tetrapropylammonium hydroxide to water in the solution of tetrapropylammonium hydroxide is 1:1.5-3.

5.

2. The ceramic composite separator of claim 1, wherein, The hierarchical zeolite has a particle size of 0.5-5μm.

3. The ceramic composite separator of claim 1, wherein, The coating comprises, in parts by mass, 60-75 parts of the hierarchical zeolite, 20-25 parts of the thickening agent, 1-5 parts of the binder, 2-5 parts of the dispersant, and 1-3 parts of the leveling agent.

4. The ceramic composite separator of claim 1, wherein, The dispersant comprises at least one of polyvinyl alcohol, polypropylene alcohol, cetylbenzenesulfonic acid, polyethylene glycol, modified polyacrylic acid, carboxyl-modified styrene-butadiene latex, polyacrylonitrile-modified copolymer, polyacrylamide, polyvinylacetamide, polyacrylammonium, polyether derivative, and polycarboxylate; And / or, the thickening agent comprises at least one of carboxymethyl cellulose, hydroxymethyl cellulose, bentonite, and attapulgite clay; And / or, the binder comprises at least one of an acrylic polymer and a polyurethane-based binder; And / or, the base film comprises at least one of polyethylene, polypropylene, a polypropylene / polyethylene / polypropylene three-layer composite film, polyimide, polyvinylidene fluoride, or non-woven fabric; And / or, the base film has a thickness of 5-20μm and a porosity of 20%-70%; And / or, the coating has a thickness of 1-5μm.

5. The method of producing a ceramic composite separator according to any one of claims 1 to 4, characterized by, The method comprises the following steps: The hierarchical zeolite, the dispersant, and water are mixed to obtain solution A; The thickening agent, the binder, the leveling agent, and water are mixed to obtain solution B; Solution A and solution B are mixed, and then coated on at least one side of the base film to prepare the ceramic composite separator after drying.

6. A lithium-ion battery, characterized by The ceramic composite separator of any one of claims 1-4 is used as a separator.

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