Lightweight flexible fiber membrane, its preparation method and application, and battery fireproof separator

Abstract

The present application provides a lightweight flexible fiber membrane, a preparation method and an application thereof, as well as a battery fireproof separator. The preparation method includes the following steps: mixing a spinning aid solution and a silica sol in a certain proportion and stirring evenly, and adding cetyltrimethylammonium bromide and paraffin oil during the stirring process to obtain a microemulsion-like electrospinning precursor solution; performing electrospray spinning on the electrospinning precursor solution in a strong electric field to form a composite nanofiber membrane; calcining the composite nanofiber membrane to finally obtain a lightweight flexible fiber membrane. The lightweight flexible fiber membrane provided by the present application, while maintaining the lightweight, heat-resistant and flame-retardant characteristics of the existing silica aerogel, effectively improves its anti-bending and folding performance through structural improvement and further reduces its thermal conductivity.

Description

Technical Field

[0001] This application relates to the technical field of heat-resistant material structures and manufacturing methods. Specifically, it provides a lightweight flexible fiber membrane with good heat insulation performance, its preparation method and application, and a battery fireproof separator. Background Art

[0002] Currently, porous materials such as silica (SiO2) aerogels on the market have a small density, are light in weight, and have excellent heat insulation and heat resistance properties. They are ideal materials for blocking heat sources, fire sources, and the external environment. However, due to the mechanical properties of the aerogel itself, such as brittleness and non-tensile properties, when such materials are used as heat insulation and fireproof layers for large-scale and large-size applications, it is generally necessary to encapsulate them with organic heat insulation spunbond outside to solve the problems of powder falling off and the inability to achieve heat insulation effect after breaking.

[0003] Obviously, this encapsulation method will greatly weaken the advantage of the light weight of silica aerogel, making the heat insulation layer structurally complex and bulky, and hindering its application in some occasions where lightweight and compact heat insulation effects need to be achieved.

[0004] For example, when blocking the thermal runaway propagation of lithium-ion batteries, which are currently widely used as power sources for new energy vehicles, in order to avoid sacrificing the energy density requirements of the battery module, it is required that the heat insulation material be thin enough and have an appropriate thermal conductivity to meet the heat insulation requirements under runaway conditions. An efficient, lightweight heat insulation membrane that can adapt to different battery sizes as a battery separator layer to prevent heat from spreading to the battery module when the battery undergoes thermal runaway is the key to achieving the safety performance of the battery pack in any state. However, the above physical encapsulation method severely limits its application in the field of heat insulation and flame retardancy of lithium-ion batteries due to the increase in the thickness and weight of the heat insulation layer.

[0005] In addition, some silica inorganic nanofiber materials have emerged on the market, but their mechanical properties are not good, their flexibility is poor, and their bending resistance is low, which also affects their large-scale application.

[0006] Therefore, it is necessary to further improve the structure and manufacturing method of the current silica heat insulation and heat resistance materials, while maintaining their good heat resistance performance, to solve the problems of existing materials such as powder falling off, poor bending resistance, insufficient flexibility, and poor mechanical properties. Summary of the Invention

[0007] The purpose of this application is to solve the problems existing in the prior art, and provide a lightweight flexible fiber membrane with good heat insulation performance and its preparation method, the application of this lightweight flexible fiber membrane in heat insulation and fire prevention, and a battery fireproof separator manufactured using this lightweight flexible fiber membrane.

[0008] The first aspect of the present application provides a method for preparing a lightweight flexible fiber membrane, comprising the following steps:

[0009] Step 100, mixing the spinning aid solution and the silica sol in a certain proportion and stirring them evenly, and adding hexadecyltrimethylammonium bromide and paraffin oil during the stirring process to obtain a microemulsion electrospinning precursor solution;

[0010] Step 200, jet-spinning the electrospinning precursor solution in a strong electric field to obtain silica-polyvinyl alcohol-paraffin oil composite nanofibers, wherein the silica-polyvinyl alcohol-paraffin oil composite nanofibers are stacked alternately during the jet spinning to form a composite nanofiber membrane;

[0011] Step 300, calcining the composite nanofiber membrane, the silica-polyvinyl alcohol-paraffin oil composite nanofibers constituting the composite nanofiber membrane are calcined to form hollow tubular silica nanofibers, and finally the lightweight and flexible fiber membrane is obtained.

[0012] Preferably, the concentration of polyvinyl alcohol in the spinning aid solution is 20-25 wt %.

[0013] Preferably, the silica sol is prepared according to the following steps: adding tetraethyl orthosilicate to an inorganic acid solution with a pH value of 2 to 3 and stirring evenly at room temperature, and tetraethyl orthosilicate undergoes hydrolysis and polycondensation reaction under acidic conditions to obtain colorless and transparent silica sol.

[0014] Preferably, the inorganic acid solution is prepared by mixing phosphoric acid and deionized water; in the preparation process of the silica sol, the molar ratio of ethyl orthosilicate, phosphoric acid and deionized water is 1:0.009-0.011:8-12.

[0015] Preferably, in step 100, the spinning aid solution and the silica sol are mixed at a mass ratio of 0.9 to 1.1:1.

[0016] Preferably, in step 200, the mass ratio of hexadecyltrimethylammonium bromide to ethyl orthosilicate required for preparing silica sol is 0.02-0.04:1, and the mass ratio of hexadecyltrimethylammonium bromide to paraffin oil is 4-10:1.

[0017] Preferably, in step 200, a single-needle syringe is used for jet spinning, the needle aperture is 0.7-0.9 mm, and the spinning speed is 1-2 mL / hour.

[0018] Preferably, the temperature for jet spinning in step 400 is 22-28° C., and the relative humidity is 35-45%. After the jet spinning in step 200 is completed, the step of drying the composite nanofiber membrane is also included.

[0019] Preferably, step 300 specifically includes the following steps:

[0020] The composite nanofiber membrane is placed in a muffle furnace, heated to a set temperature at a rate of 4 to 6°C / min, and then maintained for 2 to 4 hours to obtain the lightweight and flexible fiber membrane.

[0021] A second aspect of the present application provides a lightweight and flexible fiber membrane, wherein the lightweight and flexible fiber membrane is formed by staggered stacking of hollow tubular silica nanofibers.

[0022] Preferably, the lightweight and flexible fiber membrane is prepared using the aforementioned method for preparing a lightweight and flexible fiber membrane.

[0023] Preferably, the outer diameter of the hollow tubular silica nanofibers is 0.4-0.9 um.

[0024] Preferably, the density of the lightweight flexible fiber membrane is ≤0.0165 g / cm 3 .

[0025] A third aspect of the present application provides an application of the aforementioned lightweight flexible fiber membrane. Specifically, the application is that the lightweight flexible fiber membrane forms a heat insulation layer between targets or between the target and the external environment.

[0026] A fourth aspect of the present application provides a battery fireproof diaphragm for covering a battery, wherein the battery fireproof diaphragm is made of the aforementioned lightweight flexible fiber membrane.

[0027] The preparation method provided in the embodiment of the present application uses polyvinyl alcohol (PVA) as a spinning aid solution, mixes it with a silica (SiO2) sol, and adds a surfactant (CTAB) and an organic paraffin oil to the mixed solution and stirs it thoroughly, so that a uniformly mixed silica-polyvinyl alcohol-paraffin oil complex is produced in the electrospinning precursor solution. After the precursor solution is sprayed out from the nozzle, under the action of a high-voltage electric field, the water in the solution evaporates rapidly, the paraffin oil molecules gradually gather in the middle, and the SiO2 sol molecules and PVA are transferred to the outside, thereby forming a core-shell nanostructure with paraffin oil as the core layer and the combination structure of SiO2 sol molecules and PVA as the shell layer. The organic paraffin oil molecules that support the core layer and the PVA connecting the SiO2 sol molecules are completely removed, and finally hollow tubular SiO2 nanofibers are formed. The product obtained by this preparation method, while maintaining the good thermal insulation properties of the SiO2 material, is further formed into a specific hollow tubular fiber structure through a specific component ratio and preparation process, which greatly improves the bending resistance and reduces the overall density of the product while further improving the thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Flow chart of the preparation method of the light - weight flexible fiber membrane according to an embodiment of the present application;

[0029] Figure 2 Schematic diagram of the specific implementation process of the preparation method of the light - weight flexible fiber membrane according to an embodiment of the present application;

[0030] Figure 3a SEM image of the overall morphology of the light - weight flexible fiber membrane prepared according to an embodiment of the present application;

[0031] Figure 3b SEM enlarged - view of a part of the light - weight flexible fiber membrane prepared according to an embodiment of the present application;

[0032] Figure 3c TEM image of the light - weight flexible fiber membrane prepared according to an embodiment of the present application;

[0033] Figure 4 Schematic diagram of the anti - bending experiment of the light - weight flexible fiber membrane according to an embodiment of the present application;

[0034] Figure 5 Schematic diagram of the experiment on the flame - retardant effect of the battery thermal runaway of the battery fire - proof separator according to an embodiment of the present application;

[0035] Figure 6a Temperature change curve of multiple battery modules without a battery fire - proof separator;

[0036] Figure 6b Temperature change curve of multiple battery modules when using the battery fire - proof separator provided by the embodiment of the present application. Detailed implementation manners

[0037] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0038] Polyvinyl alcohol, tetraethyl orthosilicate, phosphoric acid, cetyltrimethylammonium bromide and paraffin oil used in the embodiments of the present application are all commercially available products.

[0039] Silica aerogel materials have the advantages of low density, light weight, good fire and heat resistance, etc., and are ideal fireproof and heat-insulating materials. However, silica heat-resistant materials in the form of aerogels generally cannot be used to prepare large-scale and large-sized fireproof and heat-insulating layers alone. The reason is that the silica aerogel material itself has a brittle structure and is prone to breakage and powdering during friction or bending, thus losing its heat-insulating effect. Therefore, it is generally necessary to coat or encapsulate heat-insulating spunbond on the outer surface of sheet-shaped silica aerogels. Obviously, although the above physical encapsulation structure can collect bent aerogel fragments or fallen aerogel powder, this measure itself does not improve the defects of weak bending resistance and tensile strength of silica aerogels, and additionally increases the thickness, weight, etc. of heat-insulating products, making it lose its application advantages in some occasions where lightweight and compact heat-insulating layers are required (such as heat-insulating treatment of lithium-ion batteries in new energy vehicles). Therefore, it is necessary to improve the existing silica aerogel form to greatly improve its bending resistance while maintaining its original heat-insulating performance, so as to expand its applicable scenarios and fields.

[0040] After analyzing the reasons for the defects existing in the above-mentioned prior art, the applicant draws on the structural characteristics of the hair of cold-region organisms such as polar bears (its hair is slender and has a hollow space inside, so as to further preserve characteristics and avoid heat loss from the body to the outside), and proposes a bionic lightweight flexible fiber membrane and its preparation method, as well as the application of the lightweight flexible fiber membrane and a battery fireproof separator manufactured using the same.

[0041] In the first aspect of the embodiments of the present application, a preparation method of a lightweight flexible fiber membrane is provided. Figure 1 The flowchart of the preparation method is shown. Figure 2 In some specific embodiments, the schematic diagram of the specific implementation process of the preparation method is shown. As Figure 1 、 Figure 2 shown, the preparation method includes the following steps:

[0042] (1) Preparation of an electrospinning precursor solution, which further includes the following steps:

[0043] Step 100, adding polyvinyl alcohol (PVA) to deionized water, heating and stirring evenly to dissolve, and cooling to prepare a spinning aid solution;

[0044] Step 200, mixing tetraethyl orthosilicate (TEOS), phosphoric acid (H3PO4), and deionized water in a certain proportion, and stirring evenly at room temperature to prepare a silica (SiO2) sol;

[0045] Step 300, the spinning aid solution obtained in step 100 and the silica sol obtained in step 200 are mixed in a certain proportion and stirred evenly, and cetyltrimethylammonium bromide (CTAB) and paraffin oil are added during the stirring process to obtain a microemulsion electrospinning precursor solution.

[0046] (2) Electrospinning, comprising the following steps:

[0047] In step 400, the electrospinning precursor solution obtained in step 300 is jet-spun in a strong electric field to obtain silica-polyvinyl alcohol-paraffin oil composite nanofibers. The silica-polyvinyl alcohol-paraffin oil composite nanofibers are stacked alternately during the jet spinning to form a composite nanofiber membrane.

[0048] (3) high temperature calcination, comprising the following steps:

[0049] Step 500, calcining the composite nanofiber membrane obtained in step 400, and the silica-polyvinyl alcohol-paraffin oil composite nanofibers constituting the composite nanofiber membrane are calcined to form hollow tubular silica nanofibers, and finally the lightweight flexible fiber membrane is obtained.

[0050] like Figure 2 As shown, the preparation method of the lightweight flexible fiber membrane provided in the present application uses polyvinyl alcohol (PVA) as a spinning aid solution on the one hand, and on the other hand, tetraethyl orthosilicate (TEOS) is subjected to a hydrolysis and condensation reaction under acidic conditions to form a silicon dioxide (SiO2) sol, which is then mixed with the PVA spinning aid solution, and organic paraffin oil is added to the mixed solution and stirred thoroughly, and a certain amount of hexadecyltrimethylammonium bromide (CTAB) is added thereto as a surfactant to uniformly disperse the paraffin oil in the mixed solution, and the electrospinning precursor solution obtained after stirring is in the form of a white microemulsion.

[0051] Furthermore, if Figure 2 As shown, during the electrospinning process, after the precursor solution is sprayed out from the nozzle, the water in the solution will evaporate rapidly under the action of the high voltage electric field, and the paraffin oil molecules will gradually gather in the middle during the spraying process, while the SiO2 sol molecules and PVA will transfer to the outside, thus forming a core-shell nanostructure with paraffin oil as the core layer and the combination structure of SiO2 sol molecules and PVA as the shell layer.

[0052] Finally, if Figure 2 As shown, after calcination, the organic paraffin oil molecules and PVA are completely removed, and finally hollow tubular SiO2 nanofibers are formed, which are stacked in an interlaced manner to form a lightweight and flexible fiber membrane.

[0053] Example 1

[0054] This embodiment provides a method for preparing a lightweight flexible fiber membrane, comprising the following steps:

[0055] (1) Preparation of electrospinning precursor solution

[0056] Preparation of PVA spinning aid solution: First, weigh PVA powder, add a certain amount of deionized water into a sealed reagent bottle, swell at room temperature for 1 hour, stir at high speed in a magnetic stirrer heated at 80°C water bath for 4 hours, and obtain a PVA solution with a concentration of 20wt%.

[0057] Preparation of SiO2 sol: TEOS was added dropwise into a phosphoric acid solution, wherein TEOS, H3PO4 and H2O were mixed in a molar ratio of 1:0.009:8. Under acidic conditions, TEOS underwent hydrolysis and polycondensation to form SiO2 sol, which was stirred at room temperature for 8 hours to obtain a colorless and transparent SiO2 sol.

[0058] Preparation of electrospinning precursor solution: SiO2 sol and PVA spinning aid solution were mixed and stirred at a mass ratio of 0.9:1 for 8 hours, and surfactant CTAB was added to the solution at the same time, wherein the mass ratio of CTAB to TEOS required for the preparation of SiO2 sol mixed with PVA spinning aid solution in this step was 0.02:1; then a certain mass of paraffin oil was added, wherein the mass ratio of CTAB to paraffin oil was 10:1, and then the mixed solution was stirred at high speed for 8 hours to obtain a white microemulsion electrospinning precursor solution.

[0059] (2) Electrospinning

[0060] In this embodiment, an E02-001 electrospinning machine produced by Foshan Qingzi Nano Co., Ltd. is used to inject the prepared precursor solution into the syringe of the electrospinning machine for electrospinning. The syringe adopts a single needle with a needle aperture of 0.7 to 0.9 mm. The spinning speed is 1 to 2 mL / hour, the spinning temperature is controlled at 22°C, and the relative humidity is controlled at 35%.

[0061] As electrospinning proceeds, the SiO2-PVA-paraffin oil composite fibers are stacked alternately on the receiver to form a composite fiber membrane. After spinning, the composite fiber membrane on the receiver is removed and placed in an electric constant temperature blast drying oven at 80°C for 2 hours to remove moisture from the fibers.

[0062] (3) High temperature calcination

[0063] The dried composite fiber membrane was placed in a muffle furnace, heated to 700°C at a rate of 5°C / min, and then kept warm for 3 hours to obtain a lightweight and flexible fiber membrane composed of staggered hollow tubular SiO2 nanofibers, which was recorded as SNF-1.

[0064] Example 2

[0065] This embodiment provides a method for preparing a lightweight flexible fiber membrane, comprising the following steps:

[0066] (1) Preparation of electrospinning precursor solution

[0067] Preparation of PVA spinning aid solution: First, weigh PVA powder, add a certain amount of deionized water into a sealed reagent bottle, swell at room temperature for 1.5 hours, stir at high speed in a magnetic stirrer heated at 80°C water bath for 5 hours, and obtain a PVA solution with a concentration of 25wt%.

[0068] Preparation of SiO2 sol: TEOS is added dropwise into a phosphoric acid solution, wherein TEOS, H3PO4, and H2O are mixed in a molar ratio of 1:0.01:10. Under acidic conditions, TEOS undergoes a hydrolysis and polycondensation reaction to form SiO2 sol, which is stirred at room temperature for 8 hours to obtain a colorless and transparent SiO2 sol.

[0069] Preparation of electrospinning precursor solution: SiO2 sol and PVA spinning aid solution are mixed and stirred in a mass ratio of 1:1 for 8 hours, and surfactant CTAB is added to the solution at the same time, wherein the mass ratio of CTAB to TEOS required for the preparation of SiO2 sol mixed with PVA spinning aid solution in this step is 0.03:1; then a certain mass of paraffin oil is added, wherein the mass ratio of CTAB to paraffin oil is 6:1, and then the mixed solution is stirred at high speed for 8 hours to obtain a white microemulsion electrospinning precursor solution.

[0070] (2) Electrospinning

[0071] In this embodiment, an E02-001 electrospinning machine produced by Foshan Qingzi Nano Co., Ltd. is used to inject the prepared precursor solution into the syringe of the electrospinning machine for electrospinning. The syringe adopts a single needle with a needle aperture of 0.7 to 0.9 mm. The spinning speed is 1 to 2 mL / hour, the spinning temperature is controlled at 25°C, and the relative humidity is controlled at 40%.

[0072] As electrospinning proceeds, the SiO2-PVA-paraffin oil composite fibers are stacked alternately on the receiver to form a composite fiber membrane. After spinning, the composite fiber membrane on the receiver is removed and placed in an electric constant temperature blast drying oven at 80°C for 2 hours to remove moisture from the fibers.

[0073] (3) High temperature calcination

[0074] The dried composite fiber membrane was placed in a muffle furnace, heated to 700°C at a rate of 5°C / min, and then kept warm for 3 hours to obtain a lightweight and flexible fiber membrane SNF-2 composed of staggered hollow tubular SiO2 nanofibers.

[0075] Example 3

[0076] This embodiment provides a method for preparing a lightweight flexible fiber membrane, comprising the following steps:

[0077] (1) Preparation of electrospinning precursor solution

[0078] Preparation of PVA spinning aid solution: First, weigh PVA powder, add a certain amount of deionized water into a sealed reagent bottle, swell at room temperature for 1.5 hours, stir at high speed in a magnetic stirrer heated at 80°C water bath for 5 hours, and obtain a PVA solution with a concentration of 25wt%.

[0079] Preparation of SiO2 sol: TEOS was added dropwise into a phosphoric acid solution, wherein TEOS, H3PO4, and H2O were mixed in a molar ratio of 1:0.011:12. Under acidic conditions, TEOS underwent hydrolysis and polycondensation reaction to form SiO2 sol, which was stirred at room temperature for 8 hours to obtain a colorless and transparent SiO2 sol.

[0080] Preparation of electrospinning precursor solution: SiO2 sol and PVA spinning aid solution were mixed and stirred at a mass ratio of 1.1:1 for 8 hours, and surfactant CTAB was added to the solution at the same time, wherein the mass ratio of CTAB to TEOS required for the preparation of SiO2 sol mixed with PVA spinning aid solution in this step was 0.04:1; then a certain mass of paraffin oil was added, wherein the mass ratio of CTAB to paraffin oil was 4:1, and then the mixed solution was stirred at high speed for 8 hours to obtain a white microemulsion electrospinning precursor solution.

[0081] (2) Electrospinning

[0082] In this embodiment, an E02-001 electrospinning machine produced by Foshan Qingzi Nano Co., Ltd. is used to inject the prepared precursor solution into the syringe of the electrospinning machine for electrospinning, wherein the syringe adopts a single needle with a needle aperture of 0.7 to 0.9 mm, a spinning speed of 1 to 2 mL / hour, a spinning temperature of 28°C, and a relative humidity of 45%.

[0083] As electrospinning proceeds, the SiO2-PVA-paraffin oil composite fibers are stacked alternately on the receiver to form a composite fiber membrane. After spinning, the composite fiber membrane on the receiver is removed and placed in an electric constant temperature blast drying oven at 80°C for 2 hours to remove moisture from the fibers.

[0084] (3) High temperature calcination

[0085] The dried composite fiber membrane was placed in a muffle furnace, heated to 700°C at a rate of 5°C / min, and then kept warm for 3 hours to obtain a lightweight and flexible fiber membrane composed of staggered hollow tubular SiO2 nanofibers, which was recorded as SNF-3.

[0086] The lightweight and flexible fiber membranes prepared in Examples 1 to 3 above contain hollow tubular silica nanofibers with an outer diameter of 0.4 to 0.9 um.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing a SiO2 fiber membrane, comprising the following steps:

[0089] (1) Preparation of electrospinning precursor solution

[0090] Preparation of PVA spinning aid solution: First, weigh PVA powder, add a certain amount of deionized water into a sealed reagent bottle, swell at room temperature for 1.5 hours, stir at high speed in a magnetic stirrer heated at 80°C water bath for 5 hours, and obtain a PVA solution with a concentration of 25wt%.

[0091] Preparation of SiO2 sol: TEOS is added dropwise into a phosphoric acid solution, wherein TEOS, H3PO4, and H2O are mixed in a molar ratio of 1:0.01:10. Under acidic conditions, TEOS undergoes a hydrolysis and polycondensation reaction to form SiO2 sol, which is stirred at room temperature for 8 hours to obtain a colorless and transparent SiO2 sol.

[0092] Preparation of electrospinning precursor solution: SiO2 sol and PVA spinning aid solution were mixed and stirred at a mass ratio of 1:1 for 8 hours to obtain a white microemulsion electrospinning precursor solution.

[0093] (2) Electrospinning

[0094] In this embodiment, an E02-001 electrospinning machine produced by Foshan Qingzi Nano Co., Ltd. is used to inject the prepared precursor solution into the syringe of the electrospinning machine for electrospinning. The syringe adopts a single needle with a needle aperture of 0.7 to 0.9 mm. The spinning speed is 1 to 2 mL / hour, the spinning temperature is controlled at 25°C, and the relative humidity is controlled at 40%.

[0095] As electrospinning proceeds, SiO2 nanofibers are stacked alternately on the receiver to form a fiber membrane. After spinning, the fiber membrane on the receiver is removed and placed in an electric constant temperature blower drying oven at 80°C for 2 hours to remove moisture from the fibers.

[0096] (3) High temperature calcination

[0097] The dried fiber membrane was placed in a muffle furnace, heated to 700°C at a rate of 5°C / min, and then kept warm for 3 hours to obtain a fiber membrane composed of staggered solid tubular SiO2 nanofibers, which was recorded as SNF.

[0098] Table 1 below lists the comparison of thermal conductivity and density of the products obtained by the preparation methods provided by Examples 1 to 3 and the preparation method provided by Comparative Example 1.

[0099] Table 1

[0100] Product Thermal conductivity <![CDATA[Density g / cm 3 > SNF1 0.0506 0.0137 SNF2 0.0412 0.0128 SNF3 0.0535 0.0165 SNF 0.054 0.025

[0101] Figure 3a , Figure 3b The overall morphology SEM images and local magnified SEM images of the lightweight and flexible fiber membranes prepared by some embodiments of the present application are shown respectively, wherein: Figure 3a The reference scale is 1um. Figure 3b The reference scale bar is 200 nm. Figure 3c TEM images of lightweight and flexible fiber membranes prepared by some embodiments of the present application are shown, with a reference scale of 1 um.

[0102] from Figures 3a to 3c It can be seen that the lightweight and flexible fiber membrane obtained by the preparation method of the present application contains SiO2 nanofibers with obvious hollow tubular structure. Compared with the comparative example, it further improves the thermal insulation performance while effectively reducing the overall density of the fiber membrane.

[0103] Figure 4 The figures show the anti-bending test results of the lightweight and flexible fiber membranes prepared by some embodiments of the present application. Figure 4 The lightweight and flexible fiber membrane on the far right still maintains its original shape after being bent 500 times, and the fiber mechanical properties remain good without any powder falling off.

[0104] Example 4

[0105] This embodiment provides a lightweight flexible fiber membrane, which is formed by stacking hollow tubular silica nanofibers in an interlaced manner. The outer diameter of the hollow tubular silica nanofibers is 0.4 to 0.9 um. The density of the lightweight flexible fiber membrane is ≤ 0.0165 g / cm 3 .

[0106] Preferably, the lightweight and flexible fiber membrane is prepared using the aforementioned method for preparing a lightweight and flexible fiber membrane.

[0107] Example 5

[0108] This embodiment provides an application of the aforementioned lightweight flexible fiber membrane. Specifically, the lightweight flexible fiber membrane is placed between target objects or between the target object and the external environment to form a heat insulation layer.

[0109] In some specific embodiments, the target object can be a heat source or a fire source. In some other specific embodiments, the target object can also be a cold source. By forming a heat insulation layer between adjacent target objects or between the target object and the external environment through the lightweight flexible fiber membrane, heat exchange between the target objects or between the target object and the external environment is avoided.

[0110] In some specific embodiments, the target object can also be a person, an animal or a non-living object that needs to be protected. By forming a heat insulation layer between the target object and the external environment with a large temperature difference through the lightweight flexible fiber membrane, the effect of preventing the external environment with overheating or overcooling from causing harm to the target object is achieved.

[0111] Example 6

[0112] This embodiment provides a battery fireproof separator for coating a battery, and the battery fireproof separator is made of the aforementioned lightweight flexible fiber membrane.

[0113] Figure 5 The results of the battery module thermal runaway flame retardant effect experiment using the battery fireproof separator provided by this embodiment are shown. As Figure 5 shown, the battery fireproof separator made of a 1.5-mm-thick lightweight flexible fiber membrane can successfully prevent the spread of battery thermal runaway in the module, and the mechanical properties of the heat insulation membrane are still good at high temperatures, indicating that this heat insulation material has a positive effect on passively solving the safety problem of the spread of battery thermal runaway.

[0114] Furthermore, the temperature change situation after ignition of a battery module composed of multiple batteries without the protection of a battery fireproof separator and with the battery fireproof separator provided by the embodiment of the present application arranged between adjacent batteries is tested. Figure 6a and Figure 6b respectively show the temperature change curves of each battery module in the two cases. In the figure, 1Front, 1Back... 5Front, 5Back respectively represent the front and back sides of 5 adjacent batteries in sequence.

[0115] As Figure 6a and Figure 6b shown, without the battery fireproof separator, when the battery module triggers battery thermal runaway, it quickly reaches a very high temperature and thermal runaway in sequence, and the thermal runaway spread of the module has a domino effect. However, the battery fireproof separator provided by the embodiment of the present application forms a good fireproof and heat insulation layer between adjacent batteries, which can ensure that even if a battery catches fire, the subsequent batteries will not experience thermal runaway.

[0116] The specific implementation manners of the present application have been described in detail above. For those skilled in the art of this technology, without departing from the principle of the present application, several improvements and modifications can still be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A preparation method of a lightweight flexible fiber membrane, the lightweight flexible fiber membrane being used for heat insulation, characterized in that, The following steps are involved: Step 100, mixing the spinning aid solution and the silica sol in a certain proportion and stirring them evenly, and adding hexadecyltrimethylammonium bromide and paraffin oil during the stirring process to obtain a microemulsion electrospinning precursor solution; Step 200, jet-spinning the electrospinning precursor solution in a strong electric field to obtain silica-polyvinyl alcohol-paraffin oil composite nanofibers, wherein the silica-polyvinyl alcohol-paraffin oil composite nanofibers are stacked alternately during the jet spinning to form a composite nanofiber membrane; Step 300, calcining the composite nanofiber membrane, the silica-polyvinyl alcohol-paraffin oil composite nanofibers constituting the composite nanofiber membrane are calcined to form hollow tubular silica nanofibers, and finally the lightweight and flexible fiber membrane is obtained; The mass ratio of the hexadecyltrimethylammonium bromide to the ethyl orthosilicate required for preparing the silica sol is 0.02-0.04:1, and the mass ratio of the hexadecyltrimethylammonium bromide to the paraffin oil is 4-10:

1.

2. The preparation method of the lightweight flexible fiber membrane according to claim 1, wherein The concentration of polyvinyl alcohol in the spinning aid solution is 20-25 wt %.

3. The preparation method of the light flexible fiber membrane according to claim 1, wherein The silica sol is prepared according to the following steps: Add ethyl orthosilicate into an inorganic acid solution with a pH value of 2 to 3 and stir evenly at room temperature. Ethyl orthosilicate undergoes hydrolysis and polycondensation reaction under acidic conditions to obtain a colorless and transparent silica sol.

4. The method for preparing a lightweight flexible fiber membrane according to claim 3, characterized in that: The inorganic acid solution is prepared by mixing phosphoric acid and deionized water; During the preparation of the silica sol, the molar ratio of ethyl orthosilicate, phosphoric acid and deionized water is 1:0.009-0.011:8-12.

5. The preparation method of the light flexible fiber membrane according to claim 1, characterized in that, In step 100, the spinning aid solution and the silica sol are mixed at a mass ratio of 0.9 to 1.1:

1.

6. The preparation method of the lightweight flexible fiber membrane according to claim 1, characterized in that, In step 200, a single needle syringe is used for jet spinning, the needle aperture is 0.7-0.9 mm, and the spinning speed is 1-2 mL / hour.

7. The method for preparing a lightweight flexible fiber membrane according to claim 1, characterized in that: The temperature for jet spinning in step 200 is 22-28° C. and the relative humidity is 35-45%; After the jet spinning in step 200 is completed, the step of drying the composite nanofiber membrane is also included.

8. The preparation method of the lightweight flexible fiber membrane according to claim 1, characterized in that, Step 300 specifically includes the following steps: The composite nanofiber membrane is placed in a muffle furnace, heated to a set temperature at a rate of 4 to 6°C / min, and then maintained for 2 to 4 hours to obtain the lightweight and flexible fiber membrane.

9. A lightweight flexible fiber membrane, characterized in that, The lightweight and flexible fiber membrane is prepared using the method for preparing a lightweight and flexible fiber membrane according to any one of claims 1 to 8.

10. The lightweight flexible fiber membrane according to claim 9, wherein The outer diameter of the hollow tubular silica nanofiber is 0.4-0.9 um.

11. The lightweight flexible fiber membrane according to claim 9, characterized in that, The density of the light flexible fiber membrane ≤ 0.0165 g / cm 3 .

12. Use of a lightweight flexible fiber membrane as described in any one of claims 9 to 11, characterized in that, The lightweight and flexible fiber membrane forms a heat insulation layer between the objects or between the objects and the external environment.

13. A battery fireproof separator for coating a battery, characterized in that, The battery fireproof diaphragm is made of the lightweight flexible fiber membrane according to any one of claims 9 to 11.

Images