A high pressure hydrothermally acidified halloysite / polyolefin battery separator and a method of making the same

Abstract

The application provides a high-pressure hydrothermal acidification halloysite / polyolefin battery diaphragm and a preparation method thereof, which comprises four steps, (1) acid immersion of halloysite, (2) high-pressure hydrothermal acidification of halloysite, (3) preparation of a high-pressure hydrothermal acidification halloysite / polyolefin diaphragm slurry, and (4) preparation of a high-pressure hydrothermal acidification halloysite / polyolefin diaphragm by coating or blending. Compared with a diaphragm prepared from halloysite without high-pressure hydrothermal acidification treatment, the diaphragm prepared by the application has a heat shrinkage rate reduction of 24.8%, a liquid absorption rate increase of 37.9%, an ion conductivity increase of 9.0%, and a discharge specific capacity increase of 8.1%. The high-pressure hydrothermal acidification halloysite / polyolefin battery diaphragm prepared by the application has the advantages of good thermal stability, high electrochemical performance and high safety performance.

Description

Technical Field

[0001] This invention belongs to the field of battery separator technology, and relates to a battery separator and its preparation method. Background Technology

[0002] Secondary batteries are widely used in new energy vehicles, electronic devices, and aerospace due to their advantages such as high energy density, long cycle life, and no memory effect. The separator, as a key component of the battery, plays a crucial role in separating the positive and negative electrodes and transporting ions. Currently, commercially available separators are mainly polyolefin separators such as polyethylene and polypropylene. Although they have advantages such as high mechanical strength and good chemical stability, their poor stability makes them prone to shrinkage, which can lead to contact between the positive and negative electrodes and cause battery explosions, posing a fire hazard. Furthermore, the low liquid absorption rate of the separator limits the battery's range. Therefore, improving separator performance and developing new technologies for preparing high-performance separators are of great significance.

[0003] Ceramicizing the separator can improve this problem, while other inorganic materials such as Al2O3 are expensive and have limited effectiveness. Natural clay minerals are not only abundant and inexpensive, with excellent dimensional stability, but also possess strong ion exchange capacity and rich porous structures. Using clay minerals as inorganic modifiers for the separator can improve the separator's liquid absorption rate, promote ion transport, enhance the battery's electrochemical performance, and thus increase its range. The addition of natural clay minerals can also enhance the separator's dimensional stability, improve battery safety, and reduce the risk of fire.

[0004] Halloysite is a nanotube-like mineral belonging to the aluminosilicate clay mineral family. The tubes range in length from 0.2 μm to 2 μm, with an outer diameter of 50 nm to 70 nm and an inner diameter of 10 nm to 30 nm. The outer surface of the halloysite nanotubes exhibits a positive charge due to the silicon-oxygen tetrahedra, while the inner cavity contains negatively charged aluminum-oxygen octahedra. The large aspect ratio and unique chemical and charge properties of halloysite nanotubes have garnered significant attention for their application in battery separators.

[0005] Chinese patent CN109004157A discloses a method for preparing halloysite-coated nonwoven lithium-ion battery separators. Halloysite nanotubes are used as the coating material, mixed with binders, modifiers, defoamers, and organic solvents to form a coating slurry. The slurry is then coated onto the surface of PET nonwoven fabric using a blade coating method to create a composite separator for lithium-ion batteries. Chinese patent CN105374971A discloses a method for coating a silane coupling agent-modified halloysite nanotube onto the surface of a polyolefin microporous membrane. Chinese patent CN114725617A discloses a method for preparing a coating slurry for lithium-ion battery separators, in which halloysite undergoes a shortening process followed by dopamine functionalization. However, these patents do not increase the inner diameter of the halloysite nanotubes, resulting in a low specific surface area and limited electrolyte wettability of the separator, thus restricting the electrochemical performance of the battery. Summary of the Invention

[0006] This invention provides a high-pressure hydrothermal acidification halloysite / polyolefin battery separator and its preparation method, aiming to improve the liquid absorption rate and dimensional stability of the separator by high-pressure hydrothermal acidification of halloysite, thereby improving the electrochemical performance and safety performance of the battery.

[0007] The technical solution provided by this invention is as follows:

[0008] A method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator includes the following specific steps:

[0009] 1) Acid leaching of halloysite, specifically: adding halloysite nanotubes to 0.4M~1.2M hydrochloric acid and stirring to mix them thoroughly;

[0010] 2) High-pressure hydrothermal acidification of halloysite, specifically: the halloysite is acid-leached in a hydrothermal reactor at a temperature of 100℃~180℃ for 6h~12h. After the reaction is completed, the halloysite is obtained by centrifugation, washing and drying.

[0011] 3) Prepare high-pressure hydrothermal acidification halloysite / polyolefin diaphragm slurry;

[0012] 4) High-pressure hydrothermal acidified halloysite / polyolefin membranes are prepared by coating or blending.

[0013] Furthermore, in step 1), halloysite nanotubes are mixed with hydrochloric acid at a ratio of 0.040 g / mL to 0.065 g / mL.

[0014] Further, in step 2), after the reaction is complete, the obtained halloysite suspension is centrifuged and washed three times with deionized water at a speed of 2500 r / min to 4000 r / min, collected by a filter device, and dried by heating at 90℃ to 110℃ for 7h to 9h to obtain high-pressure hydrothermal acidified halloysite.

[0015] Further, in step 3), high-pressure hydrothermal acidified halloysite and polyvinylidene fluoride are added to an N-methyl-2-pyrrolidone solution at a mass ratio of 95:5. The mixture is stirred at 20°C for 8 to 12 hours to obtain a uniform slurry. The slurry is then coated onto a polyolefin separator and heated at 50°C to 70°C in a vacuum drying oven for 10 to 12 hours to obtain a high-pressure hydrothermal acidified halloysite / polyolefin battery separator.

[0016] Further, in step 3), high-pressure hydrothermal acidified halloysite and polyvinylidene fluoride are added to N,N-dimethylformamide solution at a mass ratio of 0.04:1 and stirred at 20°C for 8 to 12 hours to obtain a uniform mixed slurry. The slurry is then coated onto a glass plate by blending and heated in a vacuum drying oven at 50°C to 70°C for 10 to 12 hours to obtain a high-pressure hydrothermal acidified halloysite / polyolefin battery separator.

[0017] The present invention further provides a high-pressure hydrothermal acidified halloysite / polyolefin battery separator prepared according to the above method.

[0018] The beneficial effects of this invention are:

[0019] This invention primarily uses natural halloysite minerals as raw materials, performs high-pressure hydrothermal acidification treatment, and prepares a high-pressure hydrothermal acidified halloysite / polyolefin separator slurry to prepare a battery separator, with the following specific effects:

[0020] (1) Using H + Halloysite was subjected to high-pressure hydrothermal acidification treatment with strong acid solutions of concentrations ranging from 0.4M to 1.2M, resulting in an increase in the specific surface area of ​​halloysite from 60.4 m². 2 / g increased to 133.7m 2 / g, the specific surface area is increased by more than twice, and the tubular structure of halloysite is not destroyed.

[0021] (2) Compared with commercial PP separators, the high-pressure hydrothermal acidified halloysite / polyolefin battery separator prepared in this invention has a 62.4% reduction in thermal shrinkage, a 250.9% increase in liquid absorption, a 16.7% increase in ionic conductivity, and a 33.3% increase in discharge specific capacity at 3C rate.

[0022] (3) Compared with the separator prepared by halloysite without high-pressure hydrothermal acidification, the high-pressure hydrothermal acidified halloysite / polyolefin battery separator prepared by the present invention has a reduced thermal shrinkage rate of 24.8%, an increased liquid absorption rate of 37.9%, an increased ionic conductivity of 9.0%, and an increased discharge specific capacity at 3C rate of 8.1%.

[0023] The preparation method of this invention is simple and low-cost. The high-pressure hydrothermal acidified halloysite / polyolefin battery separator prepared has advantages such as good thermal stability, high electrochemical performance, and high safety performance. It can not only improve the battery's range but also enhance its safety performance, preventing fire accidents caused by the battery. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the preparation process of the high-pressure hydrothermal acidification halloysite / polyolefin separator of the present invention.

[0026] Figure 2 Comparative diagram showing the tubular structure of halloysite in Comparative Example 2, ordinary acidification, and Example 1;

[0027] Figure 3 Comparative diagram of the cross-sectional structure of halloysite in Comparative Example 2, ordinary acidification and Example 1;

[0028] Figure 4 This is a transmission electron microscope image of HNTs in Comparative Example 2 of the present invention, with a 50 nm scale bar.

[0029] Figure 5 Transmission electron microscope image of HNTs-0.4M prepared in Example 1 of this invention, with a 50 nm scale bar;

[0030] Figure 6 The nitrogen adsorption-desorption isotherms of halloysite in Example 1 and Comparative Example 2 of this invention are shown.

[0031] Figure 7 Images showing the dimensional stability of the diaphragm in Embodiment 1, Comparative Examples 1 and 2 of the present invention;

[0032] Figure 8 The mechanical property curves of the diaphragm in Example 1, Comparative Example 1, and Comparative Example 2 of this invention are shown.

[0033] Figure 9 The rate performance curves of the lithium iron phosphate / lithium batteries assembled with separators in Example 1, Comparative Example 1, and Comparative Example 2 of this invention are shown.

[0034] Figure 10 The cycling performance curves are those of the lithium iron phosphate / lithium batteries assembled with separators in Example 1, Comparative Example 1, and Comparative Example 2 of this invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Acidified halloysite utilizes the H+ in strong acids. + The reaction with the aluminum-oxygen octahedrons on the inner wall of halloysite nanotubes increases the tube volume, specific surface area, and pore size. Existing acidification methods for halloysite nanotubes are carried out at relatively low temperatures and atmospheric pressures, resulting in a very slow reaction process, typically requiring several days to achieve the desired specific surface area and pore size. In contrast, high-pressure hydrothermal acidification is conducted in a hydrothermal reactor. Under high temperature and pressure conditions, hydrochloric acid easily enters the halloysite nanotubes, allowing the acidification reaction to be completed within hours. This not only improves reaction efficiency, reduces hydrochloric acid consumption, and decreases the difficulty of subsequent washing and waste liquid volume, but also helps to reduce production costs and environmental pollution.

[0037] High-pressure hydrothermal acidified halloysite nanotubes have higher specific surface area and inner diameter than those without high-pressure hydrothermal acidified halloysite nanotubes. Therefore, using high-pressure hydrothermal acidified halloysite as an inorganic filler to prepare battery separators can improve the liquid absorption rate of the separator, promote lithium ion transport, and thus improve the electrochemical performance of the battery.

[0038] This invention proposes a method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator, such as... Figure 1 As shown, the specific steps include the following:

[0039] 1) Acid leaching of halloysite, specifically: adding halloysite nanotubes to 0.4M~1.2M hydrochloric acid and stirring to mix them thoroughly;

[0040] 2) High-pressure hydrothermal acidification of halloysite, specifically: the halloysite is acid-leached in a hydrothermal reactor at a temperature of 100℃~180℃ for 6h~12h. After the reaction is completed, the halloysite is obtained by centrifugation, washing and drying.

[0041] 3) Prepare high-pressure hydrothermal acidification halloysite / polyolefin diaphragm slurry;

[0042] 4) High-pressure hydrothermal acidified halloysite / polyolefin membranes are prepared by coating or blending.

[0043] This method is simple and easy to implement, and it helps to improve the liquid absorption rate, ionic conductivity and dimensional stability of the separator, thereby enhancing the electrochemical performance and safety performance of the battery.

[0044] Example 1 Coating Method

[0045] High-pressure hydrothermal 0.4M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0046] The preparation process of high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene membrane is as follows:

[0047] 1) Weigh 1.3g of halloysite and place it in 30mL of 0.4M HCl solution, then stir until homogeneous;

[0048] 2) Pour into a hydrothermal reactor and react at 180℃ for 10h; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 3000r / min, collected by filtration device, and dried and ground at 100℃ for 8h to obtain high-pressure hydrothermal 0.4M hydrochloric acid acidified halloysite, named HNTs-0.4M;

[0049] 3) Weigh 0.2g HNTs-0.4M and 0.0105g polyvinylidene fluoride and add them to 3.5mL N-methyl-2-pyrrolidone solution. Stir at 20℃ for 12h to obtain a uniform slurry.

[0050] 4) The slurry was coated onto the polypropylene membrane and vacuum dried at 60°C for 12 hours to obtain a high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene membrane, named PP / HNTs-0.4M.

[0051] Performance testing of the high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene diaphragm showed that the diaphragm's thermal shrinkage rate was 18.8%. Figure 7 The tensile strength is 30.9 F / cm. Figure 8 The liquid absorption rate was 321.4% (Table 1), the ionic conductivity was 0.7 mS / cm (Table 1), and the discharge specific capacity at 3C rate in lithium iron phosphate / lithium battery systems was 123.0 mAh / g. Figure 9 ).

[0052] Compared to commercially available PP membranes, the high-pressure hydrothermal 0.4M hydrochloric acid-treated halloysite / polypropylene membrane prepared in this embodiment exhibits significant advantages. The high-pressure hydrothermal 0.4M hydrochloric acid-treated halloysite / polypropylene membrane shows a 62.4% reduction in thermal shrinkage, a 250.9% increase in liquid absorption, a 16.7% increase in ionic conductivity, and a 33.3% increase in discharge specific capacity at 3C rate. Compared to membranes prepared from halloysite without high-pressure hydrothermal acid treatment, the high-pressure hydrothermal 0.4M hydrochloric acid-treated halloysite / polypropylene membrane prepared in this embodiment shows a 24.8% reduction in thermal shrinkage, a 37.9% increase in liquid absorption, a 9.0% increase in ionic conductivity, and an 8.1% increase in discharge specific capacity at 3C rate.

[0053] The high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene separator prepared in this embodiment has low thermal shrinkage, good thermal stability, and high electrochemical performance, which enhances battery endurance and improves battery safety, thus avoiding fire accidents caused by the battery.

[0054] Example 2 Coating Method

[0055] High-pressure hydrothermal 0.8M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0056] The preparation process of high-pressure hydrothermal 0.8M hydrochloric acid-acidified halloysite / polypropylene membrane is as follows:

[0057] 1) Weigh 1.3g of halloysite and place it in 30mL of 0.8M HCl solution, then stir until homogeneous;

[0058] 2) Pour into a hydrothermal reactor and react at 140℃ for 6 hours; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 4000 r / min, collected by a filter, and dried and ground at 110℃ for 7 hours to obtain high-pressure hydrothermal 0.8M hydrochloric acid acidified halloysite, named HNTs-0.8M;

[0059] 3) Weigh 0.2g HNTs-0.8M and 0.0105g polyvinylidene fluoride and add them to 3.5mL N-methyl-2-pyrrolidone solution. Stir at 20℃ for 10h to obtain a uniform slurry.

[0060] 4) The slurry was coated onto the polypropylene membrane and vacuum dried at 50°C for 12 hours to obtain a high-pressure hydrothermal 0.8M hydrochloric acid-acidified halloysite / polypropylene membrane, named PP / HNTs-0.8M.

[0061] Example 3 Coating Method

[0062] High-pressure hydrothermal 1.2M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0063] The preparation process of high-pressure hydrothermal 1.2M hydrochloric acid-acidified halloysite / polypropylene diaphragm is as follows:

[0064] 1) Weigh 1.3g of halloysite and place it in 30mL of 1.2M HCl solution, then stir until homogeneous;

[0065] 2) Pour into a hydrothermal reactor and react at 100℃ for 12h; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 2500r / min, collected by filtration device, and dried and ground at 90℃ for 9h to obtain high-pressure hydrothermal 1.2M hydrochloric acid acidified halloysite, named HNTs-1.2M;

[0066] 3) Weigh 0.2g HNTs-1.2M and 0.0105g polyvinylidene fluoride and add them to 3.5mL N-methyl-2-pyrrolidone solution. Stir at 20℃ for 8h to obtain a uniform slurry.

[0067] 4) The slurry was coated onto the polypropylene membrane and vacuum dried at 70°C for 10 hours to obtain a high-pressure hydrothermal 1.2M hydrochloric acid-acidified halloysite / polypropylene membrane, named PP / HNTs-1.2M.

[0068] Example 4: Blending Method

[0069] High-pressure hydrothermal 0.4M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0070] The preparation process of high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene membrane is as follows:

[0071] 1) Weigh 1.3g of halloysite and place it in 30mL of 0.4M HCl solution, then stir until homogeneous;

[0072] 2) Pour into a hydrothermal reactor and react at 180℃ for 10h; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 3000r / min, collected by filtration device, and dried and ground at 100℃ for 8h to obtain high-pressure hydrothermal 0.4M hydrochloric acid acidified halloysite, named HNTs-0.4M;

[0073] 3) Weigh 0.04g of HNTs-0.4M and 1g of polyvinylidene fluoride and add them to 3.5mL of N,N-dimethylformamide solution. Stir at 20℃ for 12h to obtain a uniform slurry.

[0074] 4) The slurry was coated onto a glass plate and vacuum dried at 60°C for 12 hours to obtain a high-pressure hydrothermal 0.4M hydrochloric acid-acidified halloysite / polypropylene diaphragm, named PVDF / HNTs-0.4M.

[0075] Example 5: Blending Method

[0076] High-pressure hydrothermal 0.8M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0077] The preparation process of high-pressure hydrothermal 0.8M hydrochloric acid-acidified halloysite / polypropylene membrane is as follows:

[0078] 1) Weigh 1.3g of halloysite and place it in 30mL of 0.8M HCl solution, then stir until homogeneous;

[0079] 2) Pour into a hydrothermal reactor and react at 140℃ for 6 hours; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 4000 r / min, collected by a filter, and dried and ground at 110℃ for 7 hours to obtain high-pressure hydrothermal 0.8M hydrochloric acid acidified halloysite, named HNTs-0.8M;

[0080] 3) Weigh 0.04g of HNTs-0.8M and 1g of polyvinylidene fluoride and add them to 3.5mL of N,N-dimethylformamide solution. Stir at 20℃ for 10h to obtain a uniform slurry.

[0081] 4) The slurry was coated onto a glass plate and vacuum dried at 50°C for 12 hours to obtain a high-pressure hydrothermal 0.8M hydrochloric acid-acidified halloysite / polypropylene diaphragm, named PVDF / HNTs-0.8M.

[0082] Example 6 Blending Method

[0083] High-pressure hydrothermal 1.2M hydrochloric acid-acid halloysite / polypropylene membrane assembly battery system

[0084] The preparation process of high-pressure hydrothermal 1.2M hydrochloric acid-acidified halloysite / polypropylene diaphragm is as follows:

[0085] 1) Weigh 1.3g of halloysite and place it in 30mL of 1.2M HCl solution, then stir until homogeneous;

[0086] 2) Pour into a hydrothermal reactor and react at 100℃ for 12h; after high-pressure hydrothermal acidification, the halloysite suspension is centrifuged and washed three times with deionized water at 2500r / min, collected by filtration device, and dried and ground at 90℃ for 9h to obtain high-pressure hydrothermal 1.2M hydrochloric acid acidified halloysite, named HNTs-1.2M;

[0087] 3) Weigh 0.04g of HNTs-1.2M and 1g of polyvinylidene fluoride and add them to 3.5mL of N,N-dimethylformamide solution. Stir at 20℃ for 8h to obtain a uniform slurry.

[0088] 4) The slurry was coated onto a glass plate and vacuum dried at 70°C for 10 hours to obtain a high-pressure hydrothermal 1.2M hydrochloric acid-acidified halloysite / polypropylene diaphragm, named PVDF / HNTs-1.2M.

[0089] Comparative Example 1

[0090] Commercial polypropylene separator (Celgard 2500) battery assembly system:

[0091] This comparative example directly uses commercial polypropylene separators to assemble batteries without any processing.

[0092] Performance testing of the PP diaphragm showed that its heat shrinkage rate was 50.0%. Figure 7 The tensile strength is 30.3 F / cm. Figure 8 The liquid absorption rate was 91.6% (Table 1), the ionic conductivity was 0.6 mS / cm (Table 1), and the discharge specific capacity at 3C rate in lithium iron phosphate / lithium battery systems was 92.3 mAh / g. Figure 9 ).

[0093] In this comparative example, the thermal stability, liquid absorption rate, ionic conductivity of the separator, and the discharge specific capacity of the assembled lithium-ion battery were all low. This is because, without the addition of halloysite, the PP separator has poor wettability to the electrolyte and poor thermal stability.

[0094] Comparative Example 2

[0095] Battery system without high-pressure hydrothermal acidification halloysite / polypropylene separator assembly

[0096] The preparation process of the un-high-pressure hydrothermal acidified halloysite / polypropylene diaphragm is as follows:

[0097] The preparation method of this comparative example is basically the same as that of Example 1, except that the halloysite used was not subjected to high-pressure hydrothermal acidification. The specific steps are as follows:

[0098] Weigh 0.2g HNTs and 0.0105g polyvinylidene fluoride and add them to 3.5mL N-methyl-2-pyrrolidone solution. Stir for 12h to obtain a uniform slurry. Coat the slurry onto a polypropylene membrane and vacuum dry at 60℃ for 12h to obtain an un-high-pressure hydrothermal acidified halloysite / polypropylene membrane, named PP / HNTs.

[0099] Performance testing of the un-high-pressure hydrothermal acidified halloysite / polypropylene diaphragm showed that its thermal shrinkage rate was 25.0%. Figure 7 The tensile strength is 31.8 F / cm. Figure 8 The liquid absorption rate was 233.1% (Table 1), the ionic conductivity was 0.7 mS / cm (Table 1), and the discharge specific capacity at 3C rate in lithium iron phosphate / lithium battery systems was 113.8 mAh / g. Figure 9 ).

[0100] Compared to commercial PP membranes, the un-hydraulicized halloysite / polypropylene membrane prepared in this comparative example exhibits significant advantages. The un-hydraulicized halloysite / polypropylene membrane shows a 75.0% reduction in thermal shrinkage, a 154.5% increase in liquid absorption, a 16.7% increase in ionic conductivity, and a 23.3% increase in discharge specific capacity at 3C rate.

[0101] In this comparative example, under essentially the same preparation method, the thermal stability, liquid absorption rate, ionic conductivity, and discharge specific capacity of the assembled lithium-ion battery prepared with the membrane without high-pressure hydrothermal acidification of halloysite were lower than those of the membrane prepared with high-pressure hydrothermal acidification of halloysite. Figure 7 — Figure 10 This indicates that high-pressure hydrothermal acidification of halloysite helps to expand the specific surface area of ​​halloysite, providing more transport channels for lithium ions, thereby improving the electrochemical performance of the battery. At the same time, the addition of halloysite after high-pressure hydrothermal acidification is beneficial to improving the thermal stability of the separator.

[0102] The raw material ratios and performance parameters used in the above embodiments and comparative examples are shown in Table 1.

[0103] Table 1. Raw material ratios and performance parameters used in the examples and comparative examples.

[0104]

[0105] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator, characterized in that... The specific steps include the following: 1) Acid leaching of halloysite, specifically: adding halloysite nanotubes to 0.4M~1.2M hydrochloric acid and stirring to mix them thoroughly; 2) High-pressure hydrothermal acidification of halloysite, specifically: the halloysite is acid-leached in a hydrothermal reactor at a temperature of 100℃~180℃ for 6h~12h. After the reaction is completed, the halloysite is obtained by centrifugation, washing and drying. 3) Prepare high-pressure hydrothermal acidification halloysite / polyolefin diaphragm slurry; 4) High-pressure hydrothermal acidified halloysite / polyolefin membranes are prepared by coating or blending.

2. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 1, characterized in that: In step 1), halloysite nanotubes are mixed with hydrochloric acid at a ratio of 0.040 g / mL to 0.065 g / mL.

3. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 1, characterized in that: In step 2), after the reaction is complete, the resulting halloysite suspension is centrifuged and washed three times with deionized water at a speed of 2500 r / min to 4000 r / min, collected by a filter device, and dried by heating at 90℃ to 110℃ for 7h to 9h to obtain high-pressure hydrothermal acidified halloysite.

4. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 1, characterized in that: In step 3), high-pressure hydrothermal acidified halloysite and polyvinylidene fluoride are added to N-methyl-2-pyrrolidone solution at a mass ratio of 95:5, and stirred at 20°C for 8 to 12 hours to obtain a uniform mixed slurry.

5. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 4, characterized in that: Step 4) uses a coating method, specifically, coating the slurry onto the polyolefin separator and heating it in a vacuum drying oven at 50℃~70℃ for 10h~12h to obtain a high-pressure hydrothermal acidified halloysite / polyolefin battery separator.

6. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 1, characterized in that: In step 3), high-pressure hydrothermal acidified halloysite and polyvinylidene fluoride are added to N,N-dimethylformamide solution at a mass ratio of 0.04:1 and stirred at 20°C for 8 to 12 hours to obtain a uniform mixed slurry.

7. The method for preparing a high-pressure hydrothermal acidified halloysite / polyolefin battery separator as described in claim 6, characterized in that: In step 4), a blending method is used, specifically, the slurry is coated onto a glass plate and heated in a vacuum drying oven at 50℃~70℃ for 10h~12h to obtain a high-pressure hydrothermal acidified halloysite / polyolefin battery separator.

8. A high-pressure hydrothermal acidified halloysite / polyolefin battery separator, characterized in that: Prepared according to any one of claims 1-7.

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