A modified attapulgite-based separator and a preparation method and application thereof

Abstract

The application belongs to the technical field of battery materials, and particularly relates to a modified attapulgite-based diaphragm and a preparation method and application thereof, the preparation method comprising the following steps: performing acid washing modification or chemical modification on attapulgite to obtain modified attapulgite; mixing the modified attapulgite and a solution A to obtain a mixture B, wherein the solution A comprises a pore-forming agent; mixing the mixture B and a binder to obtain a mixed slurry C; coating the mixed slurry C on a substrate, and immersing the substrate coated with the slurry into water to form a film and form pores, and then drying the film to obtain the modified attapulgite-based diaphragm; and the obtained modified attapulgite-based diaphragm has good mechanical properties and thermal stability, and can avoid mechanical deformation caused by external force and puncture of lithium dendrites, and shrinkage caused by heat.

Description

Technical Field

[0001] This application relates to the field of battery materials technology, and more specifically, to a modified attapulgite-based separator, its preparation method, and its application. Background Technology

[0002] With the depletion of fossil fuels and the increasing environmental pollution caused by their combustion, the development of renewable and clean energy sources such as wind, hydro, solar, and tidal power has become a research hotspot. However, these clean energy sources have limitations and fluctuations in time and space, making large-scale application difficult. The emergence of new energy storage devices such as lithium-ion batteries and supercapacitors has provided a breakthrough in solving this problem, ushering in an excellent development opportunity. Lithium-ion batteries, due to their high energy density and other advantages, are widely used in electric vehicles, digital devices, and other fields, and have great development prospects.

[0003] Lithium-ion batteries mainly consist of four parts: the positive electrode, the negative electrode, the separator, and the electrolyte. The performance of the separator not only affects the battery's electrochemical performance but also has a significant impact on its safety. The separator plays two main roles in the battery: first, it prevents direct contact between the positive and negative electrode materials, thus preventing short circuits and safety accidents; second, it provides a channel for the diffusion and transport of lithium ions between the positive and negative electrodes. Due to existing problems in lithium batteries, such as lithium dendrite formation, thermal runaway, and spontaneous combustion, higher requirements are placed on the thermal stability and mechanical properties of the separator. This is to prevent safety accidents caused by deformation due to external forces during assembly, lithium dendrite puncture, and shrinkage under heat, thereby ensuring safety. Summary of the Invention

[0004] This application addresses the aforementioned deficiencies in the prior art. There is a need for a modified attapulgite-based diaphragm, its preparation method, and its application, capable of resolving the problems of mechanical deformation of the diaphragm during assembly due to external forces and lithium dendrite punctures, as well as shrinkage caused by heat.

[0005] A first aspect of this application provides a method for preparing a modified attapulgite-based membrane, the method comprising: acid-washing or chemically modifying attapulgite to obtain modified attapulgite; mixing the modified attapulgite with solution A to obtain mixture B, wherein solution A includes a pore-forming agent; mixing mixture B with a binder to obtain a mixed slurry C; coating the mixed slurry C onto a substrate, immersing the substrate coated with the slurry in water to form a film and create pores, and drying the film to obtain the modified attapulgite-based membrane.

[0006] A second aspect of this application provides a modified attapulgite-based diaphragm prepared by the preparation method described in any embodiment of this application.

[0007] A third aspect of this application provides the application of the modified attapulgite-based separator described in any embodiment of this application in a battery.

[0008] The modified attapulgite-based separators, their preparation methods, and applications provided in the various embodiments of this application utilize attapulgite, which has a rich porous structure. The attapulgite is first modified, then fully mixed with a pore-forming agent and a binder to obtain a slurry. The slurry is then coated to form a film. After the coated film is immersed in water, a phase transition process occurs, resulting in a separator with a rich pore structure. This improves the porosity and liquid absorption rate of the separator and provides a convenient channel for the rapid transport of lithium ions. Based on the good properties of attapulgite, a separator with good mechanical properties and thermal stability is obtained through the film formation and pore-forming process. Attached Figure Description

[0009] In drawings that are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with or without letter suffixes may indicate different instances of similar parts. The drawings generally illustrate various embodiments by way of example rather than limitation and are used, together with the description and claims, to illustrate the claimed embodiments. Where appropriate, the same reference numerals are used in all drawings to refer to the same or similar parts. Such embodiments are illustrative and not intended to be exhaustive or exclusive embodiments of the apparatus or method.

[0010] Figure 1 The thermal stability diagrams of the modified attapulgite-based diaphragms prepared according to different embodiments of this application are shown.

[0011] Figure 2 A scanning electron microscope image of the modified attapulgite-based diaphragm prepared according to Example 1 of this application is shown.

[0012] Figure 3 The LSV curves of modified attapulgite-based membranes and commercial PP membranes prepared according to different embodiments of this application are shown. Detailed Implementation

[0013] To enable those skilled in the art to better understand the technical solutions of this application, the application will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific examples, but these are not intended to limit the scope of this application.

[0014] The terms “first,” “second,” and similar words used in this application do not indicate any order, quantity, or importance, but are merely used for distinction. Words such as “including” or “comprising” mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility of covering other elements as well.

[0015] According to an embodiment of this application, a method for preparing a modified attapulgite-based membrane is provided. The method includes: acid-washing or chemically modifying attapulgite to obtain modified attapulgite; mixing the modified attapulgite with solution A to obtain mixture B, wherein solution A includes a pore-forming agent; mixing mixture B with a binder to obtain a mixed slurry C; coating the mixed slurry C onto a substrate, immersing the substrate coated with the slurry in water to form a film and create pores, and drying the film to obtain the modified attapulgite-based membrane.

[0016] This application selects attapulgite as the raw material for the separator. Attapulgite is a natural mineral with a well-developed porous structure, which gives the separator high porosity, electrolyte absorption rate and ionic conductivity, further ensuring the battery's high specific capacity and high rate performance. Secondly, natural minerals have excellent thermal stability and mechanical properties, which can endow the separator with thermal stability and mechanical properties, prevent the separator from shrinking when heated, and prevent mechanical deformation when lithium dendrites puncture or external forces occur.

[0017] In this application, attapulgite is acid-washed or chemically modified. On the one hand, acid washing can etch a large number of nanoscale pores inside the attapulgite, thereby improving the overall porosity and liquid absorption rate of the diaphragm. On the other hand, chemical modification can selectively graft different functional patterns onto the surface of the attapulgite, thereby achieving a strong interaction between the chemically modified attapulgite and the binder, further significantly enhancing the overall stability of the diaphragm.

[0018] After attapulgite is mixed with a pore-forming agent and a binder, a film is first formed. Then, pores are created in water. This phase transition process ensures a tight bond between the modified attapulgite particles in the membrane, resulting in a uniform pore structure with suitable size and a dense distribution. Consequently, the modified attapulgite membrane exhibits good mechanical properties and thermal stability. The modified attapulgite-based membrane obtained in this application showed no shrinkage deformation at 160°C and only slight deformation at 180°C.

[0019] In some embodiments, the acid washing modification includes: mixing the attapulgite with an acid solution and then heating the mixture to obtain modified attapulgite.

[0020] In some embodiments, the acid solution is an inorganic acid solution, including one of hydrochloric acid, sulfuric acid, and nitric acid; the heating conditions for acid washing modification include a temperature of 65-80 °C and a time of 2-5 h. Better modification results can be obtained by modifying attapulgite under these conditions.

[0021] In some embodiments, after acid washing and modification, the attapulgite is centrifuged, and the resulting attapulgite is washed and dried. The drying temperature is 100-120 °C.

[0022] In some embodiments, the chemical modification includes: mixing attapulgite, a modifier, and a mixed solution D, followed by heat treatment to obtain modified attapulgite, wherein the mixed solution D includes glacial acetic acid, ethanol, and water. The modified attapulgite membrane obtained after chemical modification has a better liquid absorption rate than the modified attapulgite membrane obtained after acid modification.

[0023] In some embodiments, the modifier is one of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), polymethyl methacrylate (PMMA), cetyltrimethylammonium bromide (CTAB), etc.; the heating conditions for chemical modification include: a temperature of 65-85 °C and a time of 3-8 h.

[0024] In some embodiments, the pore-forming agent is one or more of polyvinylpyrrolidone (PVP), dimethylacetamide (DMAc), polyethylene glycol (PEG), etc. In some embodiments, the organic solvent of solution A is one or more of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetone (ACE), chloroform (TCM), etc. In some embodiments, the process of mixing the pore-forming agent and the organic solvent to obtain solution A is carried out at room temperature and is stirred. In some embodiments, during the process of mixing modified attapulgite and solution A to obtain mixture B, ultrasonic dispersion is performed for 1-3 hours at room temperature to improve the mixing uniformity.

[0025] In some embodiments, the mixed slurry C after mixing mixture B and binder is subjected to heat treatment; the conditions for heat treatment of the mixed slurry C include a temperature of 50-70 °C and a time of 12-30 h.

[0026] In some embodiments, the binder is one or more of polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), or polyvinylidene fluoride (PVDF). The combination of modified attapulgite and the binder yields a separator suitable for use in batteries, resulting in a separator with good porosity, thermal stability, and mechanical properties.

[0027] In some embodiments, the mass ratio of attapulgite to pore-forming agent is 5-7:1. In some embodiments, the mass ratio of modified attapulgite to binder is 0.1-0.5:1. Preferably, the mass ratio of modified attapulgite to binder is 0.2-0.3:1.

[0028] In some embodiments, coating the mixed slurry C onto the substrate includes: applying the mixed slurry C onto the substrate using a coating machine. The substrate may include a glass plate or the like. Further, the height between the coating machine and the substrate is 150-250 µm.

[0029] In some embodiments, the time for immersing the substrate coated with slurry in water to form a film and create pores is 24-48 h. In some embodiments, the water temperature is room temperature when immersing the substrate coated with slurry in water to form a film.

[0030] In some embodiments, the film is freeze-dried after formation. The minimum freeze-drying temperature is -65 °C, and the time is 30-40 h.

[0031] According to embodiments of this application, a modified attapulgite-based diaphragm prepared by the preparation method described in any embodiment of this application is also provided.

[0032] In some embodiments, the thickness of the modified attapulgite-based diaphragm is 80-90 µm.

[0033] According to embodiments of this application, an application of the modified attapulgite-based separator described in any embodiment of this application in a battery is also provided.

[0034] According to embodiments of this application, a battery is also provided, the battery comprising the modified attapulgite-based separator described in any embodiment of this application. Furthermore, the battery also includes a positive electrode, a negative electrode, etc.

[0035] Example 1

[0036] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0037] Step (1), Preparation of acid-washed attapulgite: Take 6 g of attapulgite and add it to a beaker. Add 55 ml of deionized water and 5 ml of 37% concentrated hydrochloric acid. Stir the hydrochloric acid solution with the attapulgite in an oil bath at 75 ℃ for 4 h. Centrifuge and wash, and dry at 110 ℃ to obtain acid-washed attapulgite.

[0038] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0039] Step (3): Add 0.1 g of acid-washed attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0040] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0041] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0042] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0043] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0044] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (HATP0.1) prepared by the method described in Example 1 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0045] Scanning electron micrograph of the modified attapulgite-based diaphragm (HATP0.1) is shown below. Figure 2 As shown. By Figure 2 Scanning electron microscopy images show that attapulgite is uniformly distributed in the membrane, which can significantly enhance the mechanical properties and thermal stability of the heat-resistant modified attapulgite-based membrane. At the same time, the dissolution of solvent and pore-forming agent produces a rich pore structure, which can not only improve the liquid absorption rate of the membrane, but also provide a convenient channel for the rapid transport of lithium ions.

[0046] The prepared heat-resistant modified attapulgite-based separator was used to assemble a half-cell. The assembly sequence of the half-cell was as follows: positive electrode shell, spring, gasket, positive electrode sheet, separator, lithium sheet, and negative electrode shell. The positive electrode was lithium iron phosphate (LiFePO4) with a diameter of 10 mm. The separator was the prepared heat-resistant modified attapulgite-based separator with a diameter of 19 mm. The electrolyte was 1 M LiPF6. Figure 3 The LSV curves of the modified attapulgite-based diaphragm (Examples 1-8) show that it remains stable at a voltage of 4.5 V.

[0047] Example 2

[0048] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0049] Step (1), Preparation of acid-washed attapulgite: Take 6 g of attapulgite and add it to a beaker. Add 55 ml of deionized water and 5 ml of 37% concentrated hydrochloric acid. Stir the hydrochloric acid solution with the attapulgite in an oil bath at 75 ℃ for 4 h. Centrifuge and wash, and dry at 110 ℃ to obtain acid-washed attapulgite.

[0050] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0051] Step (3): Add 0.2 g of acid-washed attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0052] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0053] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0054] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0055] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0056] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (HATP0.2) prepared by the method described in Example 2 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0057] Example 3

[0058] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0059] Step (1), Preparation of acid-washed attapulgite: Take 6 g of attapulgite and add it to a beaker. Add 55 ml of deionized water and 5 ml of 37% concentrated hydrochloric acid. Stir the hydrochloric acid solution with the attapulgite in an oil bath at 75 ℃ for 4 h. Centrifuge and wash, and dry at 110 ℃ to obtain acid-washed attapulgite.

[0060] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0061] Step (3): Add 0.3 g of acid-washed attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0062] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0063] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0064] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0065] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0066] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (HATP0.3) prepared by the method described in Example 3 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0067] Example 4

[0068] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0069] Step (1), Preparation of acid-washed attapulgite: Take 6 g of attapulgite and add it to a beaker. Add 55 ml of deionized water and 5 ml of 37% concentrated hydrochloric acid. Stir the hydrochloric acid solution with the attapulgite in an oil bath at 75 ℃ for 4 h. Centrifuge and wash, and dry at 110 ℃ to obtain acid-washed attapulgite.

[0070] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0071] Step (3): Add 0.4 g of acid-washed attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0072] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0073] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0074] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0075] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0076] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (HATP0.4) prepared by the method described in Example 4 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0077] Example 5

[0078] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0079] Step (1), Preparation steps of chemically modified attapulgite: Dilute glacial acetic acid with deionized water to a glacial acetic acid solution with pH=3, add 50 ml of anhydrous ethanol to 100 ml of glacial acetic acid solution, and then add 10 g of attapulgite and 0.3 g of silane coupling agent (KH-550) to the mixed solution. Stir in an oil bath at 70 ℃ for 6 h; centrifuge and wash, and dry at 110 ℃ to obtain chemically modified attapulgite.

[0080] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0081] Step (3): Add 0.1 g of modified attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0082] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0083] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0084] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0085] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0086] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (MATP0.1) prepared by the method described in Example 5 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0087] Example 6

[0088] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0089] Step (1), Preparation steps of chemically modified attapulgite: Dilute glacial acetic acid with deionized water to a glacial acetic acid solution with pH=3, add 50 ml of anhydrous ethanol to 100 ml of glacial acetic acid solution, and then add 10 g of attapulgite and 0.3 g of silane coupling agent (KH-550) to the mixed solution. Stir in an oil bath at 70 ℃ for 6 h; centrifuge and wash, and dry at 110 ℃ to obtain chemically modified attapulgite.

[0090] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0091] Step (3): Add 0.2 g of modified attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0092] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0093] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0094] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0095] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0096] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (MATP0.2) prepared by the method described in Example 6 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0097] Example 7

[0098] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0099] Step (1), Preparation steps of chemically modified attapulgite: Dilute glacial acetic acid with deionized water to a glacial acetic acid solution with pH=3, add 50 ml of anhydrous ethanol to 100 ml of glacial acetic acid solution, and then add 10 g of attapulgite and 0.3 g of silane coupling agent (KH-550) to the mixed solution. Stir in an oil bath at 70 ℃ for 6 h; centrifuge and wash, and dry at 110 ℃ to obtain chemically modified attapulgite.

[0100] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0101] Step (3): Add 0.3 g of modified attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0102] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0103] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0104] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0105] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0106] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (MATP0.3) prepared by the method described in Example 7 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0107] Example 8

[0108] This embodiment relates to a method for preparing a heat-resistant modified attapulgite-based diaphragm, comprising the following steps:

[0109] Step (1), Preparation steps of chemically modified attapulgite: Dilute glacial acetic acid with deionized water to a glacial acetic acid solution with pH=3, add 50 ml of anhydrous ethanol to 100 ml of glacial acetic acid solution, and then add 10 g of attapulgite and 0.3 g of silane coupling agent (KH-550) to the mixed solution. Stir in an oil bath at 70 ℃ for 6 h; centrifuge and wash, and dry at 110 ℃ to obtain chemically modified attapulgite.

[0110] Step (2): Add 1.0 g of pore-forming agent polyvinylpyrrolidone to 9.5 ml of organic solvent N,N-dimethylformamide (DMF), and stir at room temperature for 0.5 h until the pore-forming agent is completely dissolved to obtain solution A.

[0111] Step (3): Add 0.4 g of modified attapulgite to solution A and ultrasonically disperse at room temperature for 1 h to obtain mixture B;

[0112] Step (4): Add 1.0 g of adhesive polyvinylidene fluoride (PVDF) to mixture B, stir in an oil bath at 50 °C for 12 h to obtain mixed slurry C;

[0113] Step (5): Place the mixed slurry C on a glass plate and use a scraper (height selected 250 µm) to evenly coat the slurry on the glass plate;

[0114] Step (6): Immerse the glass plate coated with slurry into deionized water to achieve phase conversion and film formation. The depth of the deionized water is 1 cm above the glass plate, the water temperature is room temperature, and the immersion time is 24 h.

[0115] Step (7): Place the film-forming sample in a freeze-drying oven. The minimum freeze-drying temperature is -65 °C and the time is 36 h.

[0116] The thermal stability test of the heat-resistant modified attapulgite-based diaphragm (MATP0.4) prepared by the method described in Example 8 is as follows: Figure 1 As shown. By Figure 1 It is evident that the prepared heat-resistant modified attapulgite-based membrane did not undergo thermal shrinkage at 160 ℃, while the commercial PP membrane underwent significant shrinkage at 160 ℃. When the temperature continued to rise to 180 ℃, the commercial PP membrane shrank severely, while the prepared heat-resistant modified attapulgite-based membrane only underwent slight shrinkage.

[0117] The commercial PP membrane and the heat-resistant modified attapulgite-based membranes in Examples 1-8 were subjected to performance tests, and the test data are shown in Table 1.

[0118] Table 1 Battery separator performance of various embodiments

[0119]

[0120] The performance of the modified attapulgite-based separators in Examples 1-8 demonstrates that the modified attapulgite-based separators have relatively uniform thickness, a porosity greater than 50%, and a liquid absorption rate greater than 500%. Therefore, as separators for lithium batteries, they can enable lithium batteries to exhibit better electrochemical performance. The modified attapulgite-based separators obtained in each example show a thermal shrinkage rate of 0% at 160 °C, indicating good safety performance and preventing safety accidents at high temperatures.

[0121] Furthermore, although exemplary embodiments have been described herein, their scope includes any and all embodiments based on this application that have equivalent elements, modifications, omissions, combinations (e.g., schemes involving intersections of various embodiments), adaptations, or alterations. Elements in the claims will be interpreted broadly based on the language used in the claims and are not limited to the examples described in this specification or during the implementation of this application, which will be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered illustrative only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0122] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. Other embodiments may be used by those skilled in the art upon reading the above description. Furthermore, in the above detailed description, various features may be grouped together to simplify the application. This should not be construed as an intention that a feature of an unclaimed application is necessary for any claim. Rather, the subject matter of this application may be less than all the features of an embodiment of a particular application. Thus, the following claims are incorporated herein by reference as examples or embodiments, wherein each claim is independently considered as a separate embodiment, and these embodiments are contemplated as being possible in various combinations or arrangements. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

[0123] The above embodiments are merely exemplary embodiments of this application and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the spirit and scope of this application, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A process for the preparation of a modified attapulgite-based separator, characterized in that, The preparation method comprises: modifying attapulgite by acid washing or chemical modification to obtain modified attapulgite; mixing the modified attapulgite and solution A to obtain mixture B, wherein the solution A comprises a pore-forming agent; mixing the mixture B and a binder to obtain mixed slurry C; coating the mixed slurry C on a substrate, and immersing the substrate coated with the slurry into water to form a film and form pores, and drying the film to obtain a modified attapulgite-based separator; The process of mixing the modified attapulgite and solution A to obtain mixture B is performed by ultrasonic dispersion treatment, and the ultrasonic dispersion treatment is performed for 1-3 h. The pore-forming agent is polyvinylpyrrolidone and / or polyethylene glycol. The organic solvent of the solution A is one or more of N,N-dimethylformamide, N-methylpyrrolidone, acetone and chloroform. The substrate is a glass plate.

2. The production method according to claim 1, characterized by, The acid washing modification comprises: mixing the attapulgite and an acid solution, and then performing heat treatment to obtain modified attapulgite.

3. The production method according to claim 2, characterized by, The acid solution is an inorganic acid solution, and the inorganic acid solution comprises one of hydrochloric acid, sulfuric acid and nitric acid; the heat treatment condition of the acid washing modification comprises: a temperature of 65-80 DEG C and a time of 2-5 h.

4. The method of claim 1, wherein, The chemical modification comprises: mixing the attapulgite, a modifier and mixed solution D, and then performing heat treatment to obtain modified attapulgite, wherein the mixed solution D comprises glacial acetic acid, ethanol and water.

5. The production method according to claim 4, characterized by, The modifier is one of γ-aminopropyltriethoxysilane, γ-glycidyl ether propyltrimethoxysilane, polymethyl methacrylate and cetyltrimethylammonium bromide; the heat treatment condition of the chemical modification comprises: a temperature of 65-85 DEG C and a time of 3-8 h.

6. The production method according to claim 1, characterized by, The mixed slurry C obtained by mixing the mixture B and the binder is subjected to heat treatment; the heat treatment condition of the mixed slurry C comprises: a temperature of 50-70 DEG C and a time of 12-30 h; and the binder is polyvinylidene fluoride.

7. The production method according to claim 1, characterized by, The time for immersing the substrate coated with the slurry into water to form a film and form pores is 24-48 h.

8. The modified attapulgite-based separator prepared by the preparation method of any one of claims 1-7.

9. The application of the modified attapulgite-based separator of claim 8 in a battery.

Images