A ceramic micro-nano fiber aerogel material, its preparation method and application

Abstract

The present invention discloses a ceramic micro-nano fiber aerogel material, a preparation method thereof, and an application. The preparation method includes the following steps: preparing a polymer solution, preparing a precursor solution, preparing a precursor, and sintering the precursor. In the preparation method of the present invention, a second silicon source is introduced into the precursor solution, and during the preparation process, the specified order of putting raw materials and the stirring speed of the stirrer are followed to ensure that the first silicon source and the second silicon source can be hydrolyzed sufficiently and uniformly, obtaining a stable non-Newtonian fluid precursor solution, effectively extending the spinning window period of the precursor solution, thereby avoiding the problem of frequent replacement of the precursor solution, and improving the production efficiency of the ceramic micro-nano fiber aerogel material. At the same time, the prepared ceramic micro-nano fiber aerogel material has a low fiber density, a finer fiber diameter, and has good heat insulation effect.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano fiber materials, and particularly to a ceramic micro-nano fiber aerogel material, a preparation method thereof, and an application thereof. Background Art

[0002] Micro-nano fiber aerogel is a new type of high-performance fiber, a super-light and porous new type of high-performance fiber directly obtained through sol-gel spinning and special drying techniques. Micro-nano fiber aerogel combines aerogel and nanofiber technologies, and has the advantages of both. It is a perfect embodiment of the aerogel structure in fiber materials. Micro-nano fiber aerogel has the characteristics of high porosity, low density, excellent heat insulation and adsorption capabilities, and is widely used in the fields of energy storage, sound insulation and heat insulation, catalysis, filtration, etc.

[0003] Centrifugal spinning technology is a common method for preparing nano-scale fiber materials. During the centrifugal spinning process, a polymer solution is injected into the liquid storage mechanism of the spinning disk, ejected through a needle, and then under the action of the rotating centrifugal force, the polymer solution will be stretched into extremely fine fibers, and finally deposited and collected on the collection net to form a nano-scale fiber membrane or fiber bundle.

[0004] TEOS, namely tetraethyl orthosilicate, is a commonly used silicon source and is widely used in the preparation of SiO2 fiber aerogel. SiO2 fiber aerogel uses the PVP / TEOS system as a precursor, and SiO2 fiber aerogel with low thermal conductivity can be prepared by using centrifugal spinning technology. However, in the existing preparation methods, the spinnability retention time of the PVP / TEOS precursor solution during the spinning process is limited, and it usually loses spinnability within 1 hour after the precursor solution is completely hydrolyzed, and there are problems such as a short spinning window period and poor stability of the PVP / TEOS precursor solution. During the process of preparing the ceramic micro-nano fiber aerogel material, if the precursor solution loses spinnability, it is necessary to remove the precursor solution in the liquid storage tank, and reconfigure and fill a new precursor solution, which greatly limits the production efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a ceramic micro-nano fiber aerogel material, a preparation method thereof, and an application thereof, so as to solve the problem that the precursor solution has a short spinning window period in the existing preparation methods and needs to be frequently replaced.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a ceramic micro-nano fiber aerogel material, which is prepared from a precursor solution. The precursor solution includes a polymer, a first silicon source, a second silicon source, and a catalyst; the second silicon source includes one of a silane with three oxygen groups and a silane with two oxygen groups; the preparation method includes the following steps:

[0008] Prepare a polymer solution: Dissolve the polymer in a solvent and stir at a first stirring speed for a first stirring time until the solution is uniform to form a polymer solution;

[0009] Prepare a precursor solution: Add the first silicon source and the second silicon source to the polymer solution, stir at a second stirring speed, and gradually add the catalyst dropwise during the stirring process. After the second stirring time, let it stand to obtain a precursor solution;

[0010] Prepare a precursor: Spin the spinnable precursor solution into solid micro-nano fibers using a spinning device, and the micro-nano fibers accumulate on the collecting device to form fibers, obtaining a ceramic micro-nano fiber aerogel precursor;

[0011] Sinter the precursor: Place the ceramic micro-nano fiber aerogel precursor in a furnace for sintering, the sintering temperature is 950-1100 °C, and the sintering time is 0.8-1.2 h. After sintering, a ceramic micro-nano fiber aerogel material is obtained.

[0012] In the method for preparing the ceramic micro-nano fiber aerogel material, the first silicon source is tetraethyl orthosilicate, and the second silicon source includes one of 3-aminopropyltrimethoxysilane (APMTS), γ-glycidoxypropyltrimethoxysilane (GPTMS), dimethyldimethoxysilane (DMDMS), and methyltrimethoxysilane (MTMS).

[0013] In the method for preparing the ceramic micro-nano fiber aerogel material, the concentration of the polymer is 0.0007-0.0013 mol / L; the concentration of the first silicon source is 0.96-1.20 mol / L; the concentration of the second silicon source is 0.18-0.48 mol / L; the concentration of the catalyst is 0.15-0.25 mol / L.

[0014] In the method for preparing the ceramic micro-nano fiber aerogel material, the molar ratio of the first silicon source to the second silicon source is 7:1-1:1.

[0015] In the method for preparing the ceramic micro-nano fiber aerogel material, in the step of preparing the precursor solution, the polymer solution is placed in an environment of 25-40 °C and stirred at a second stirring speed.

[0016] In the preparation method of the ceramic micro-nano fiber aerogel material, the first stirring speed is 400-800 rpm; the first stirring time is 6-8 h;

[0017] The second stirring speed is 400-1200 rpm; the second stirring time is 5-24 h.

[0018] In the preparation method of the ceramic micro-nano fiber aerogel material, in the step of preparing the precursor, the relative humidity of the spinning environment is 20-30%.

[0019] In the preparation method of the ceramic micro-nano fiber aerogel material, the polymer includes at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyethylene oxide;

[0020] The solvent includes at least one of water, formic acid, tetrahydrofuran, acetone, acetylacetone, butanone, n-hexane, cyclohexane, n-heptane, acetonitrile, N-methylpyrrolidone, 1,2-propanediol, chloroform, dichloromethane, 1,2-dichloroethane, methanol, ethanol, isopropanol, 1-methoxy-2-propanol, tert-butanol, n-butanol, n-propanol, toluene, xylene, ethylenediamine, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and carbon tetrachloride;

[0021] The catalyst includes at least one of hydrochloric acid, phosphoric acid, acetic acid and citric acid.

[0022] The present invention provides a ceramic micro-nano fiber aerogel material, which is prepared according to the above preparation method.

[0023] The present invention provides an application of the above ceramic micro-nano fiber aerogel material as a heat insulation sheet between battery cells, a heat insulation pad between a battery module and a housing, or a heat insulation barrier between the outside of a battery pack and a carriage.

[0024] One technical solution in the present invention can have the following beneficial effects:

[0025] In the preparation method of the present invention, a second silicon source is introduced into the precursor solution, and during the preparation process, the specified order of putting raw materials and the stirring speed of the stirrer are followed to ensure that the first silicon source and the second silicon source can be hydrolyzed fully and uniformly, obtaining a stable non-Newtonian fluid precursor solution, effectively extending the spinning window period of the precursor solution, thereby avoiding the problem of frequent replacement of the precursor solution and improving the production efficiency of the ceramic micro-nano fiber aerogel material. At the same time, the prepared ceramic micro-nano fiber aerogel material has a low fiber density and a finer fiber diameter, and has good heat insulation effect. Description of the Drawings

[0026] Figure 1 It is the appearance diagram of the sample in Embodiment 1 of the present invention;

[0027] Figure 2 It is the appearance diagram of the sample in Embodiment 4 of the present invention;

[0028] Figure 3 It is the appearance diagram of the sample in Embodiment 6 of the present invention;

[0029] Figure 4 It is the appearance diagram of the sample in Embodiment 7 of the present invention;

[0030] Figure 5 It is the appearance diagram of the sample in Embodiment 5 of the present invention;

[0031] Figure 6 It is the appearance diagram of the sample in Embodiment 9 of the present invention;

[0032] Figure 7 It is the density analysis result diagram of Embodiment 1, Embodiment 4 and Embodiment 6 of the present invention;

[0033] Figure 8 It is the fiber diameter analysis diagram of Embodiment 1, Embodiment 4 and Embodiment 6 of the present invention;

[0034] Figure 9 It is the SEM diagram of Embodiment 5 of the present invention;

[0035] Figure 10 It is the SEM diagram of a single fiber in Embodiment 5 of the present invention. Detailed implementation manners

[0036] The technical solutions of the present invention will be further described below through specific implementation manners. For the convenience of understanding the present invention, the present invention will be described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the understanding of the disclosure content of the present invention is more thorough and comprehensive.

[0037] For those not specified in the embodiments in terms of specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments not specified in terms of the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0039] Please refer toFigures 1 to 10 , the present invention provides a method for preparing a ceramic micro-nano fiber aerogel material, the ceramic micro-nano fiber aerogel material is prepared from a precursor solution, the precursor solution includes a polymer, a first silicon source, a second silicon source and a catalyst; the second silicon source includes one of a silane having three oxygen groups and a silane having two oxygen groups; the preparation method includes the following steps:

[0040] Prepare a polymer solution: Dissolve the polymer in a solvent and stir at a first stirring speed for a first stirring time until the solution is uniform to form a polymer solution;

[0041] Prepare a precursor solution: Add the first silicon source and the second silicon source to the polymer solution, stir at a second stirring speed, and dropwise add the catalyst during the stirring process. After the second stirring time, let it stand to obtain a precursor solution;

[0042] Prepare a precursor: Spin the spinnable precursor solution into solid micro-nano fibers using a spinning device, and the micro-nano fibers accumulate on the collecting device to form fibers, obtaining a ceramic micro-nano fiber aerogel precursor;

[0043] Sinter the precursor: Put the ceramic micro-nano fiber aerogel precursor into a boiler for sintering, the sintering temperature is 950-1100 °C, the sintering time is 0.8-1.2 h, and the sintered ceramic micro-nano fiber aerogel material is obtained.

[0044] In the preparation method of the present invention, a second silicon source is introduced into the precursor solution, and during the preparation process, following the specified order of putting raw materials and the stirring speed of the stirrer, it is ensured that the first silicon source and the second silicon source can be hydrolyzed sufficiently and uniformly to obtain a stable non-Newtonian fluid precursor solution, effectively extending the spinning window period of the precursor solution, thereby avoiding the problem of frequent replacement of the precursor solution and improving the production efficiency of the ceramic micro-nano fiber aerogel material. At the same time, the prepared ceramic micro-nano fiber aerogel material has a low fiber density, a finer fiber diameter, and good heat insulation effect.

[0045] The spinning device is a centrifugal spinning device or a centrifugal electrospinning device, and the specific spinning process of the spinning device includes:

[0046] Load the precursor solution: When the environmental humidity inside the centrifugal spinning machine drops to about 30%, turn on the power to start the equipment, the spinning disk starts to rotate driven by the motor, set the rotation speed of the spinning disk to 200 rpm, load the precursor solution into the liquid storage tank, and make the precursor solution evenly spread in the liquid storage tank;

[0047] Fiber Formation and Collection: After loading the precursor solution, adjust the rotation speed of the spinning disk to 4000 rpm, and the spinning disk rotates at a high speed. If the precursor solution maintains spinnability, the precursor solution will be ejected from the needles of the spinning disk and stretched into fine filaments in the air, and fibers will be formed after air drying at normal temperature and pressure. Under the action of the wind from the upper fan, the fibers are collected on the collection net; if the precursor solution loses spinnability, no fibers will be generated.

[0048] In the step of sintering the precursor, the boiler is heated from 20 °C to 1000 °C at a rate of 5 °C / min, held for 1 hour, and then naturally cooled to room temperature to obtain the ceramic micro-nano fiber aerogel material.

[0049] Specifically, the first silicon source is tetraethyl orthosilicate, and the second silicon source includes one of 3-aminopropyltrimethoxysilane (APMTS), γ-glycidoxypropyltrimethoxysilane (GPTMS), dimethyldimethoxysilane (DMDMS), and methyltrimethoxysilane (MTMS).

[0050] Both the second silicon source and tetraethyl orthosilicate belong to silicate esters, and they are chemically compatible and can co-hydrolyze and polycondense in the same solution, keeping the PVP / TEOS / GPTMS system stable. Moreover, the addition of the second silicon source changes the concentration and distribution of silicic acid groups in the system. The hydroxyl groups generated by the hydrolysis of the second silicon source itself also participate in the condensation reaction, thereby affecting the formation rate of the silicon-oxygen bond (-Si-O-Si-), slowing down the process of the condensation reaction, contributing to the slow and uniform progress of the polycondensation reaction, thus avoiding premature gelation or too high solution viscosity, and being beneficial to maintaining good spinning conditions.

[0051] In a preferred embodiment, (3-glycidylpropoxy)trimethoxysilane is used as the second silicon source. The amino group of (3-glycidylpropoxy)trimethoxysilane interacts with the carboxyl or keto group of the polymer to form a more stable polymer network, maintaining the structural integrity and stable rheological properties of the solution, forming a structure in which TEOS is wrapped by a silane coupling agent, making the hydrolysis of TEOS slow. Coupled with gentle stirring, the structural integrity and stable rheological properties of the solution are maintained, thereby extending the spinning window period of the precursor solution.

[0052] In addition, (3-glycidoxypropyl)trimethoxysilane can regulate the viscosity and reaction rate. The methoxy groups (-OMe) in (3-glycidoxypropyl)trimethoxysilane undergo hydrolysis reactions in the solution system to form hydroxyl groups (-OH). The hydrolysis reaction rate of (3-glycidoxypropyl)trimethoxysilane is slower than that of tetraethyl orthosilicate. Therefore, in the entire system, the addition of (3-glycidoxypropyl)trimethoxysilane can slow down the overall hydrolysis and polycondensation rates, thereby helping to extend the spinning window period of the solution.

[0053] Specifically, the concentration of the polymer is 0.0007 - 0.0013 mol / L; the concentration of the first silicon source is 0.96 - 1.20 mol / L; the concentration of the second silicon source is 0.18 - 0.48 mol / L; the concentration of the catalyst is 0.15 - 0.25 mol / L.

[0054] With the above concentrations, while ensuring the smooth hydrolysis of the first silicon source, the hydrolysis rate of the first silicon source is appropriately delayed, thereby extending the spin time of the precursor solution. The molecular weight of PVP is 1 million. In a specific embodiment of the present invention, the polymer solution is obtained by mixing 15 g of PVP powder with 85 g of deionized water, and the mass fraction of the PVP solution is calculated to be 15%.

[0055] Preferably, the molar ratio of the first silicon source to the second silicon source is 7:1 - 1:1. With the above concentrations, while ensuring the stability of the precursor solution system, the prepared ceramic micro-nano fiber aerogel material is more fluffy.

[0056] Specifically, in the step of preparing the precursor solution, the polymer solution is placed in an environment of 25 - 40 °C and stirred at a second stirring speed.

[0057] Since the hydrolysis and polycondensation rates of tetraethyl orthosilicate and (3-glycidoxypropyl)trimethoxysilane are faster at high temperatures, if the temperature in the step of preparing the precursor solution is higher than 40 °C, the spinning window period of the precursor solution will be shortened. In a specific embodiment of the present invention, the step of preparing the precursor solution is carried out in a constant temperature water bath stirrer, and the catalyst is gradually added dropwise.

[0058] Specifically, the first stirring speed is 400 - 800 rpm; the first stirring time is 6 - 8 h;

[0059] The second stirring speed is 400 - 1200 rpm; the second stirring time is 5 - 24 h.

[0060] The purpose of the first stirring process for preparing the polymer solution is to disperse the polymer and make it more uniformly distributed in the solution. The purpose of the second stirring process for preparing the precursor solution is to disperse the first silicon source, the second silicon source and the catalyst, improve the uniformity of the first silicon source, the second silicon source and the catalyst in the solution, make the hydrolysis and polycondensation reactions of the first silicon source and the second silicon source more complete, and tend to form a more uniform and slightly loose three-dimensional network structure. These network structures contribute to the formation of a material with large pores and low density during subsequent drying or heat treatment processes. Therefore, the longer the stirring time for preparing the precursor solution, the fluffier the obtained fibers.

[0061] However, when the stirring time of the second stirring process for preparing the precursor solution is greater than 24 h, the fibers become rough and there will be a large number of droplets on the fiber surface. The droplets will increase the adhesion force between the fibers, resulting in the fiber bundles being prone to aggregation and entanglement, which may affect the mechanical properties of the material, such as elasticity and tensile strength. Therefore, too long a stirring time is not conducive to the formation of a uniform SiO2 fiber aerogel, and the spinning effect will deteriorate instead.

[0062] Specifically, in the step of preparing the precursor, the relative humidity of the spinning environment is 20 - 30%.

[0063] Controlling the relative humidity at 20 - 35%, the obtained fibers are dry and fluffy, which is convenient for collection. If the humidity of the spinning environment is too high, the drying speed of the fibers will slow down, there will be more droplets on the surface of the fiber membrane, and then the phenomenon of fiber adhesion will occur, which is not conducive to collecting fluffy fibers.

[0064] Specifically, the polymer includes at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyethylene oxide;

[0065] The solvent includes at least one of water, formic acid, tetrahydrofuran, acetone, acetylacetone, butanone, n-hexane, cyclohexane, n-heptane, acetonitrile, N-methylpyrrolidone, 1,2-propanediol, chloroform, dichloromethane, 1,2-dichloroethane, methanol, ethanol, isopropanol, 1-methoxy-2-propanol, tert-butanol, n-butanol, n-propanol, toluene, xylene, ethylenediamine, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and carbon tetrachloride;

[0066] The catalyst includes at least one of hydrochloric acid, phosphoric acid, acetic acid and citric acid.

[0067] The raw materials of polyvinyl alcohol are relatively inexpensive, and the production process is relatively mature, so the large-scale production cost is relatively low. However, PVP has high thermal stability, can be spun and heat-treated at relatively high temperatures, and is not easily decomposed, while polyvinyl alcohol has relatively low thermal stability and is easily decomposed under high-temperature conditions. Moreover, polyvinyl alcohol has a certain hygroscopicity and easily absorbs moisture in the environment, which may affect the application of ceramic micro-nano fiber aerogel materials in humidity-sensitive environments.

[0068] Polyethylene oxide has low toxicity, high tensile properties, and can form fine and continuous fibers, which is suitable for preparing nanofibers. However, compared with polyvinylpyrrolidone, polyethylene oxide has poor thermal stability and relatively low mechanical strength.

[0069] The type of catalyst will affect the hydrolysis and polycondensation reaction rates. The hydrolysis reaction rate is faster under acid catalysis and slower under base catalysis; in the specific embodiments of the present invention, an acidic catalyst is used.

[0070] In some specific embodiments of the present invention, the solvent used is water, and the polymer is one of polymers such as polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene oxide (PEO), etc.; the catalyst is phosphoric acid, abbreviated as PA.

[0071] The present invention also provides a ceramic micro-nano fiber aerogel material, which is prepared according to the above preparation method.

[0072] The ceramic micro-nano fiber aerogel material prepared by the above method has the characteristics of fluffy fibers, that is, low fiber density and finer fiber diameter, and has heat insulation and heat preservation functions.

[0073] The present invention also provides an application of the above ceramic micro-nano fiber aerogel material as a heat insulation sheet between battery cells, a heat insulation pad between a battery module and a housing, or a heat insulation barrier between the outer part of a battery pack and a carriage.

[0074] The ceramic micro-nano fiber aerogel material obtained by the above preparation method has excellent heat insulation performance and chemical stability, and can be applied between battery cells, between a battery module and a housing, or between the outer part of a battery pack and a vehicle to achieve the purpose of heat insulation and heat preservation, prevent heat conduction, and maintain the stability of the battery internal temperature, thereby providing the safety and stability of new energy vehicles.

[0075] Example group

[0076] A preparation method of a ceramic micro-nano fiber aerogel material, the preparation method comprising the following steps:

[0077] Preparing a polymer solution: Dissolve the polymer in a solvent according to the ratio in Table 1, and stir at a first stirring speed for a first stirring time until the solution is uniform to form a polymer solution;

[0078] Preparing a precursor solution: Add a first silicon source and a second silicon source to the polymer solution according to the ratio in Table 1, stir at a second stirring speed, and dropwise add a catalyst during the stirring process. After the second stirring time, let it stand to obtain a precursor solution;

[0079] Preparing a precursor: Spin the spinnable precursor solution into solid micro-nano fibers using a spinning device, and the micro-nano fibers accumulate on the collecting device to form fibers, obtaining a ceramic micro-nano fiber aerogel precursor;

[0080] Sintering the precursor: Put the ceramic micro-nano fiber aerogel precursor into a muffle furnace for sintering, heat it from 20°C to 1000°C at a rate of 5°C / min, and keep it at a constant temperature for 1 hour to sinter and obtain a ceramic micro-nano fiber aerogel material.

[0081] Table 1 - Composition ratio and preparation parameters of the precursor solution

[0082]

[0083] Among them, the first stirring speed is 500 rpm, the second stirring speed is 800 rpm, and the relative humidity of the spinning environment is 30%. The first silicon source is tetraethyl orthosilicate, and the second silicon source is (3-glycidyl propoxy) trimethoxysilane; the solvent used is selected from water. In Examples 1 to 14, the polymer is selected as polyvinylpyrrolidone. In Examples 15 to 17, the polymer is selected as polyethylene oxide. In Examples 18 to 20, the polymer is selected as polyvinyl alcohol; the catalyst is phosphoric acid.

[0084] In addition, the precursor solutions in Examples 10 and 12 to 14 have a very high viscosity, have lost fluidity, and are in a gel state. After being prepared, they cannot be spun.

[0085] Example 21

[0086] The preparation method and components of Example 21 are the same as those of Example 1, except that the relative humidity of the spinning environment is 40%.

[0087] Visually observe the ceramic micro-nano fiber aerogel materials sintered in Examples 1 to 21 to judge the state of the fibers, and conduct density analysis on Examples 1, 4, and 6 among them, that is, cut the obtained ceramic micro-nano fiber aerogel materials into regular blocks, measure their length, width, and height using a vernier caliper to calculate their volume, and then measure their mass using a balance to obtain the density of the fibers; analyze the fiber diameter using a scanning electron microscope. The density analysis results are shown in Figure 7 , and the fiber diameter analysis results are shown inFigure 8 Scanning electron microscopy observation was carried out on Example 5 with better fiber state.

[0088] Among them, in Examples 15 - 20, the polymer solution was replaced for the spinning experiment. In Examples 15 - 17, the polymer was selected as polyethylene oxide, and the spinning state was good, and the fiber state was dry and fluffy; in Examples 18 - 20, the polymer was selected as polyvinyl alcohol, and the spinning state was good, and the fibers were easy to absorb moisture and adhere.

[0089] Comparing Example 1, Example 4 and Example 6, it can be seen that the higher the molar ratio of the first silicon source to the second silicon source, the better the stability of the system. However, due to the organic functional groups in the second silicon source, such as epoxy groups, more chemical cross - links can be caused, which is not conducive to obtaining fluffy SiO2 fibers.

[0090] Comparing Example 6 and Example 7, it can be seen that the higher the stirring temperature, the more rapid the hydrolysis and polycondensation of tetraethyl orthosilicate and (3 - glycidoxypropyl) trimethoxysilane, and the worse the stability of the system. Appropriately extending the stirring time is beneficial to obtaining SiO2 fibers with lower density and finer fiber diameter. However, when the stirring time is too long, both the fiber diameter and density will increase, and a large number of droplets will appear on the fiber surface, affecting its mechanical properties.

[0091] According to Figure 7 it can be known that as the content of the second silicon source increases, the density of the obtained fibers increases. The reason is that after the second silicon source is hydrolyzed, a siloxane network structure is formed. A higher content of the second silicon source means the formation of more cross - link points, thus increasing the density of the network structure and therefore increasing the overall density of the fibers; moreover, the second silicon source is prone to undergo condensation reactions through its functional groups to form a more complex network structure. As the content of the second silicon source increases, the condensation reaction is more thorough, and the formed three - dimensional network structure is more compact, and the density of the fibers increases accordingly.

[0092] After the stirring time was extended from 5 h to 10 h, the fiber diameter decreased slightly. When stirring for 5 hours, due to insufficient stirring time, the hydrolysis and polycondensation reactions of the first silicon source and the second silicon source in the solution may be insufficient, PVP could not be fully unwound and dispersed, and the viscosity of the precursor solution was relatively low, unable to effectively stretch into fine fibers, thus forming a coarser fiber structure. As the stirring time increases, the hydrolysis and polycondensation of the first silicon source and the second silicon source are more sufficient, the PVP molecules are better unwound and dispersed, improving the uniformity of the solution viscosity, and finally optimizing the fiber diameter.

[0093] When the stirring time is extended from 10h to 24h, the fiber diameter increases. The reason is speculated to be that the longer stirring time allows the precursors to be fully mixed, the polycondensation reaction time is long, and larger siloxane (Si-O-Si) aggregates are formed, thus forming thicker fibers; and, as the stirring time increases, the polymers in the solution may aggregate, increasing the viscosity of the solution through self-entanglement and mutual physical entanglement. Higher solution viscosity will lead to thicker fiber formation during the spinning process.

[0094] When collecting the ceramic micro-nano fiber aerogel precursor of Example 15, compared with Example 1, the humidity in Example 15 is too high, resulting in a slower fiber drying speed, more droplets on the fiber membrane surface, and then fiber adhesion, which is not conducive to collecting fluffy fibers.

[0095] pass Figure 10 It can be obtained that the diameter of the ceramic micro-nano fiber aerogel material is about 1.4μm. By comparing the diameter of the SiO2 fiber produced by the PVP / TEOS system with the diameter of the SiO2 fiber produced by the PVP / TEOS / GPTMS system, it can be found that after adding GPTMS, the fiber diameter is smaller under appropriate stirring time, which is conducive to the preparation of aerogel materials with lower thermal conductivity.

[0096] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A preparation method of a ceramic micro-nano fiber aerogel material, characterized in that, The ceramic micro-nano fiber aerogel material is prepared from a precursor solution, and the precursor solution includes a polymer, a first silicon source, a second silicon source, and a catalyst; the second silicon source includes one of a silane with three oxygen groups and a silane with two oxygen groups; the preparation method includes the following steps: Prepare a polymer solution: Dissolve the polymer in a solvent and stir at a first stirring speed for a first stirring time until the solution is uniform to form a polymer solution; Prepare a precursor solution: Add the first silicon source and the second silicon source to the polymer solution, stir at a second stirring speed, dropwise add the catalyst during the stirring process, and let it stand after the second stirring time to obtain a precursor solution; Prepare a precursor: Spin the spinnable precursor solution into solid micro-nano fibers using a spinning device, and the micro-nano fibers accumulate on the collecting device to form fibers, obtaining a ceramic micro-nano fiber aerogel precursor; Sinter the precursor: Put the ceramic micro-nano fiber aerogel precursor into a furnace for sintering, the sintering temperature is 950 - 1100 °C, the sintering time is 0.8 - 1.2 h, and sinter to obtain the ceramic micro-nano fiber aerogel material; The first silicon source is tetraethyl orthosilicate, and the second silicon source includes one of 3-aminopropyltrimethoxysilane (APMTS), γ-glycidoxypropyltrimethoxysilane (GPTMS), dimethyldimethoxysilane (DMDMS), and methyltrimethoxysilane (MTMS); The concentration of the polymer is 0.0007 - 0.0013 mol / L; the concentration of the first silicon source is 0.96 - 1.20 mol / L; the concentration of the second silicon source is 0.18 - 0.48 mol / L; the concentration of the catalyst is 0.15 - 0.25 mol / L; The polymer includes at least one of polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene oxide; The solvent includes at least one of water, formic acid, tetrahydrofuran, acetone, acetylacetone, butanone, n-hexane, cyclohexane, n-heptane, acetonitrile, N-methylpyrrolidone, 1,2-propanediol, chloroform, dichloromethane, 1,2-dichloroethane, methanol, ethanol, isopropanol, 1-methoxy-2-propanol, tert-butanol, n-butanol, n-propanol, toluene, xylene, ethylenediamine, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and carbon tetrachloride; The catalyst includes at least one of hydrochloric acid, phosphoric acid, acetic acid, and citric acid.

2. The preparation method of a ceramic micro-nano fiber aerogel material according to claim 1, characterized in that, The molar ratio of the first silicon source to the second silicon source is 7:1 - 1:

1.

3. The preparation method of a ceramic micro-nano fiber aerogel material according to claim 1, characterized in that, In the step of preparing the precursor solution, place the polymer solution in an environment of 25 - 65 °C and stir at the second stirring speed.

4. The preparation method of a ceramic micro-nano fiber aerogel material according to claim 1, characterized in that, The first stirring speed is 400 - 800 rpm; the first stirring time is 6 - 8 h; The second stirring speed is 400 - 1200 rpm; the second stirring time is 5 - 24 h.

5. The preparation method of a ceramic micro-nano fiber aerogel material according to claim 1, characterized in that, In the step of preparing the precursor, the relative humidity is 20 - 45%.

6. A ceramic micro-nano fiber aerogel material, characterized in that, The ceramic micro-nano fiber aerogel material is prepared according to the preparation method described in any one of claims 1 - 5.

7. Use of the ceramic micro-nano fiber aerogel material as described in claim 6 as a heat insulation sheet between battery cells, a heat insulation pad between a battery module and a housing, or a heat insulation barrier between the exterior of an outer battery pack and a vehicle compartment.

Images