Compression type light fireproof aerogel material as well as preparation method and application thereof

Abstract

The invention relates to a compressed light fireproof aerogel material as well as a preparation method and application thereof, and belongs to the technical field of advanced functional materials. The fireproof aerogel material is prepared by a sol-gel method and a drying process: a FeCl3 aqueous solution is used as an acid catalyst and a reactant, and a trace amount of Fe < 3 + > is hydrolyzed and fused into a polymer network skeleton while a silicon source is catalyzed to be hydrolyzed; the aerogel material provided by the invention has a highly branched structure in which kelp knot-shaped or coralline-shaped particles and spherical particles are mutually doped, the density is 50-150 kg / m < 3 >, the water contact angle is 100-155 degrees, the compression strength is 0.3-1.6 MPa, and the maximum compression strain is greater than or equal to 70%. The preparation method disclosed by the invention is green and environment-friendly, low in process cost and easy for large-scale production. The aerogel material disclosed by the invention has high compressive strength, high rebound resilience, excellent hydrophobicity and fireproof performance, and is particularly suitable for the field with extremely high requirements on space and safety.

Description

TECHNICAL FIELD

[0001] The present application relates to a compressed light fireproof aerogel material and a preparation method thereof, and belongs to the technical field of advanced functional materials. BACKGROUND

[0002] With the development of technology, especially the rapid development of high-end technologies represented by new energy, aerospace, etc., such application scenarios have put forward higher requirements for the performance of high-end thermal insulation and flame-retardant materials. For example, in the field of new energy batteries, the thermal runaway problem of power batteries is an important safety challenge faced by the industry. If a single cell experiences thermal runaway and cannot effectively block the spread of heat and flames, it will trigger a chain reaction within minutes, leading to the loss of control of the entire battery pack and resulting in catastrophic consequences.

[0003] Aerogel materials are considered ideal thermal insulation and flame-retardant materials due to their extremely low thermal conductivity and excellent fireproof performance. However, traditional aerogel materials still have the following key problems in the actual application of new energy vehicles: ① Poor space compatibility: the gap between the cells and modules inside the battery pack is usually only 1-3 millimeters, while the thickness of traditional aerogel blocks or conventional felt materials is usually greater than 10 millimeters, making it difficult to be implanted in narrow spaces; if the thickness is forcibly reduced, it will seriously affect the overall thermal insulation and fireproof effect. ② Insufficient mechanical performance: continuous vibration and impact during vehicle operation, as well as expansion stress caused by battery charging and discharging, require thermal insulation materials to have good compression lightness, flexibility, and fatigue resistance. Traditional aerogels are highly brittle and have poor toughness, and are prone to pulverization under long-term stress, reducing the protective effect and even possibly causing electrical short circuits, causing greater harm. ③ Insufficient high-temperature resistance and fireproof rating: the temperature released during battery thermal runaway can reach 800-1200℃ in a short time, and the continuous working temperature is often above 200℃. Traditional organic or carbon-based aerogels are prone to melting, burning, or structural collapse under these conditions. ④ Lightweight requirement: under the premise of meeting the requirements of thermal insulation and flame retardation, further lightweighting of the material helps to improve the endurance. Although traditional aerogel materials have a relatively low density (about 100-220 kg / m 3 ), further lightweighting is still of great significance.

[0004] Therefore, it is necessary to develop a new light fireproof aerogel material that can have high resilience, excellent mechanical strength, excellent temperature resistance and fireproof performance in an ultra-thin form, meeting the requirements of high-end scenarios for thermal insulation and flame-retardant materials. SUMMARY

[0005] The material has the characteristics of ultra-thin form, light weight, high strength, high-temperature thermal insulation, and high-efficiency fireproofing, and is particularly suitable for fields with strict space and safety requirements, such as thermal barrier protection for new energy vehicle power battery systems, aerospace thermal insulation, building fireproofing and thermal insulation, etc.

[0006] To achieve precise, efficient and reliable protection of critical heat propagation paths in battery systems.

[0007] The present invention aims to provide a compressible lightweight fire-resistant aerogel material and its preparation method to solve the problems of insufficient adaptability, mechanical properties / reliability and stability under extreme temperature fields of existing aerogel materials.

[0008] The first aspect of this invention provides a method for preparing a compressible lightweight fire-retardant aerogel material, which is obtained by a sol-gel method and a drying process, specifically including the following steps: S1. Dissolve 0.01~0.20 parts of surfactant in 99.60~99.98 parts by weight of deionized water, then add 0.01~0.20 parts by weight of Fe. 3+ Salts are mixed evenly to prepare an iron salt / surfactant aqueous solution; A silicon source solution was prepared by mixing methylalkoxysilane with a tetrafunctional silicon source at a volume ratio of 100~80:0~20 and stirring continuously. S2. Preparation of silica sol: 70-90 parts by volume of the iron salt / surfactant aqueous solution and 10-30 parts by volume of the silicon source are mixed and then hydrolyzed at 10-30°C with stirring for 0.5-6.0 h to form silica sol; The mixing method in step S2 is as follows: the iron salt / surfactant aqueous solution is added dropwise to the silicon source solution, or the silicon source solution is added dropwise to the iron salt / surfactant aqueous solution. S3. Preparation of silica gel: Add the alkaline catalyst to the silica sol obtained in step S2, stir for 0.1~5 min, and control the pH to 6.5~8.0; pour into a mold and let stand at 10℃~50℃ for 1~168 h to obtain silica gel; S4. The silica gel described in step S3 is dried in an environment of 40~110℃ for 6~96 h to obtain a compressed lightweight fire-resistant aerogel material.

[0009] In some implementations, in step S2, the molar ratio (h value) of hydrolyzed water to silicon source is 45~65; In some embodiments, in step S2, Fe in the silica sol 3+ Salt concentration (C) acid The concentration is 0.4~1.0 mM, more preferably 0.60~0.96 mM; In some embodiments, the base catalyst in step S3 is one or a combination of ammonia, ethylenediamine, triethylamine, and pyridine; In some embodiments, in step S3, the pH is adjusted to 6.5-8.0 by adding an alkaline catalyst; In some embodiments, in step S3, the pH is adjusted to control the total alkali molar concentration in the sol to be 6-14 mM, preferably 7-10 mM.

[0010] Furthermore, the preparation method further includes a silica gel modification step: placing the silica gel in a hydrophobic modification solution and heating it at 10℃~60℃ for 3~24 h; subsequently, removing the silica gel, exchanging the solvent, and discarding the liquid phase to obtain the modified silica gel. When the silicon source is a mixed silicon source, and contains a tetrafunctional silicon source, and the volume fraction of the tetrafunctional silicon source among all silicon sources is greater than 5%, hydrophobic modification is required. In some preferred embodiments, the hydrophobic modification step uses n-hexane as the exchange solvent and is heated for 6~24 h.

[0011] In some embodiments, the surfactant is selected from one or a combination of cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), polyoxyethylene-polyoxypropylene triblock copolymer (F127), and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123).

[0012] In some embodiments, the Fe 3+ The salt is selected from one or a combination of ferric chloride, ferric sulfate, ferric nitrate, and ferric ammonium sulfate and their hydrates; ferric chloride is preferred.

[0013] In some embodiments, the silicon source is a complex of methylalkoxysilane and a tetrafunctional silicon source; the methylalkoxysilane is one or both of methyltrimethoxysilane (MTMS) and methyltriethoxysilane (MTES), and the tetrafunctional silicon source is one or a combination of methyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), water glass, and silica sol. In some implementations, in step S3, the aging and settling process, the settling temperature and settling time are dependent on each other: when the settling temperature is 10~18℃, the settling time is 20~168 h; when the settling temperature is 18~30℃, the settling time is 3~120 h; when the settling temperature is 30~40℃, the settling time is 2~96 h; and when the settling temperature is 40~50℃, the settling time is 1~48 h.

[0014] A second aspect of the present invention provides a compressible lightweight fire-retardant aerogel material, wherein the aerogel network skeleton has a branched structure, including skeleton particles and neck regions connecting the skeleton particles; the skeleton particles include a structure of interdoped kelp-like or coral-like particles and spherical particles, and the skeleton particles are connected to each other through the neck regions; the size of the skeleton particles is 100~3500 nm.

[0015] Furthermore, the density of the aerogel material is 50~150 kg / m³.3 The water contact angle is 100°~155°.

[0016] In some embodiments, the aerogel material further includes a precipitated phase embedded in the network framework; the precipitated phase is a Fe / Si-O-OH precipitated phase. Furthermore, the aerogel network framework particles are composed of =Fe-O-Si≡, =Fe-O-Fe= and ≡Si-O-Si≡ networks, and methyl groups are grafted into the network framework.

[0017] Furthermore, the aerogel network framework comprises elements such as Si, O, C, and Fe, with an atomic percentage of 10~35:30~60:15~40:0~2; Furthermore, the composition of the precipitate phase includes elements such as Si, O, C and Fe, with an atomic percentage of 1~20:30~60:15~40:1~20.

[0018] Furthermore, the compressive strength of the aerogel material is 0.3~1.6 MPa, more preferably 0.4~1.6 MPa, and particularly preferably 0.5~1.6 MPa.

[0019] Furthermore, the maximum compressive strain of the aerogel material is ≥70%, preferably ≥80%.

[0020] In some embodiments, when the compression rate is 2.0 mm / min, the stress of the aerogel material increases exponentially with increasing strain in the strain range of 60% to 85%. In some embodiments, the slope of the aerogel material in the strain range of 20% to 40% is 0.02 to 0.50, which is less than the slopes in the strain ranges of 0% to 10% and 60% to 100%, respectively. In some embodiments, the aerogel material has a stress of 0.01 MPa to 0.10 MPa at 20% strain; In some embodiments, the aerogel material has a stress of 0.02 MPa to 0.30 MPa at 40% strain; In some embodiments, the aerogel material has a stress of 0.04 MPa to 0.80 MPa at 60% strain; In some embodiments, the aerogel material has a stress of 0.10 MPa to 2.0 MPa at 80% strain.

[0021] Furthermore, the maximum stress of the aerogel material in the first 50 compression cycles at a maximum strain of 40% decreases by 10% to 50% compared to the maximum stress in the first compression cycle; Furthermore, the maximum stress of the aerogel material in 150-400 compression cycles at a maximum strain of 40% decreases by less than 50% compared to the maximum stress in the first compression cycle. Furthermore, after any compression cycle in the first 50 to 200 compression cycle tests is terminated, the aerogel material is allowed to stand for 4 days, and then its compression cycle performance is tested again under the same conditions. The maximum stress measured in the first cycle after standing is equivalent to or greater than the maximum stress measured in the last cycle before standing.

[0022] In this invention, if the silicon source is composed only of methylalkoxysilane, the compressible lightweight fire-resistant aerogel material prepared includes iron-doped polymethylsilsesquioxane (Fe-PMSQ) aerogel and Fe-PMSQ aerogel composite felt; if the silicon source is a mixture of methylalkoxysilane and tetrafunctional silicon source, the compressible lightweight fire-resistant aerogel material prepared includes iron-doped silicon (Fe-silica) aerogel and Fe-silica aerogel composite felt.

[0023] A third aspect of the present invention provides a fire-resistant aerogel composite felt, which is prepared by impregnating the aforementioned silica sol into a fiber felt, followed by gelation and drying. Furthermore, the thermal conductivity of the aerogel composite felt at 25°C is ≤40 mW / (m·K), preferably ≤35 mW / (m·K); In some embodiments, the density of the aerogel composite felt is 50~200 kg / m³. 3 .

[0024] Further, the preparation method of the fireproof aerogel composite felt is as follows: an alkaline catalyst is added to the silica sol obtained in step S2, stirred for 0-5 min, and the pH is adjusted to 6.5-8.5; then the silica sol is impregnated into the fiber felt through osmosis or negative pressure; it is placed at 10℃-50℃ and left to stand for 1-168 h to obtain silica gel felt; after drying, the aerogel composite felt can be obtained.

[0025] In some embodiments, the density of the fiber felt is 10~180 kg / m³. 3 .

[0026] In some embodiments, the fiber mat is selected from glass fiber, pre-oxidized fiber and ceramic fiber.

[0027] The fourth aspect of the present invention provides the application of the compressed lightweight fire-resistant aerogel material and the application of the fire-resistant aerogel composite felt, which are applied in the fields of thermal barrier protection for power battery systems of new energy vehicles, aerospace thermal insulation, and building fire protection and thermal insulation.

[0028] In some embodiments, the drying process of the silicone gel felt is an atmospheric pressure drying process or a supercritical drying process.

[0029] In some embodiments, the composite felt is a sheet with a thickness of 0.3 to 10.0 mm, with a thermal conductivity of ≤40 mW / (m·K) at 25°C and ≤60 mW / (m·K) at 300°C; and a compressive stress greater than 0.15 MPa and 0.3 MPa at 30% and 40% compressive strain, respectively.

[0030] Beneficial effects The compressed lightweight fire-retardant aerogel material and its preparation method obtained by this invention have the following outstanding characteristics: (1) The present invention first provides a compressible lightweight fire-retardant aerogel material, which has the characteristics of being lightweight, flexible, superelastic, having high compressive strength and high fatigue resistance; the density range of the material is 50~150 mg / cm³. 3 It has a low thermal conductivity of 15~35mW / (m·K) at room temperature; it can withstand working temperatures above 200℃ for a long time, and maintains its structure without collapsing, melting, or burning under short-term high-temperature flame impact at 1200℃, meeting the Class A non-combustible standard, and does not release toxic fumes in the flame.

[0031] (2) The aerogel composite felt made from the aerogel material of the present invention can be processed into sheets of 0.3 to 10.0 mm, which is suitable for small space applications; and has excellent fatigue resistance. It can maintain structural integrity and functional stability after long-term vibration and thousands of compression cycles, while playing a supporting and buffering role.

[0032] (3) The preparation method of the present invention is green and environmentally friendly. It does not require the use of organic solvents, highly corrosive acids or expensive supercritical drying equipment throughout the process. It uses safe and harmless acid catalysts, achieving green, environmentally friendly and low-cost manufacturing throughout the entire process. The process route is simple, safe to operate, energy-saving and environmentally friendly, and has good prospects for large-scale production and market promotion. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the embodiments of the present application to explain the application and do not constitute a limitation thereof. In the drawings: Figure 1 The gelation behavior of the sol prepared in Example 1 under different molar concentrations of ammonia and total alkali; Figure 2 The gel time of the sol prepared in Example 1 varies with the pH of the sol and the total molar concentration of the alkali; Figure 3 Infrared spectrum of the aerogel prepared in Example 1; Figure 4 XPS spectra of the aerogel prepared in Example 1: (b1) full spectrum, and fitted plots of (b2) C 1s, (b3) O 1s and (b4) Si 2p peaks; Figure 5 SEM image of the aerogel prepared in Example 1; Figure 6 Effect of total alkali molar concentration on Fe-PMSQ aerogel: (a) density; (b) linear shrinkage rate; Figure 7 Axial compression behavior of Fe-PMSQ aerogel: (a, b) Typical stress-strain curves of the aerogel sample prepared in Example 1: Note: Figure 7 The shaded areas in (a, b) represent the brittle (light blue), elastic (orange), and compressible (light green) stages, respectively. Figure 8 A comparison of the mechanical properties of the Fe-PMSQ aerogel prepared in this invention and conventional silica aerogel. Figure 9 Cyclic compression properties of aerogel sample 1M-40 prepared in Example 1; (a1) 60% strain, 5.0 mm / min; (b1) 40% strain, 5.0 mm / min; (c1) 40% strain, 2.0 mm / min; During the cycles corresponding to (a2)-(c2): Red line (top) - evolution of irrecoverable strain with the number of cycles; Orange line (middle) - evolution of energy loss per cycle with the number of cycles; Blue line (bottom) - evolution of peak stress with the number of cycles; Figure 10 Macroscopic morphology, density, and linear shrinkage of the aerogel samples prepared in Example 2: (a1)~(a9): with increasing FeCl3 concentration C acid Macroscopic morphology of Fe-PMSQ aerogels; (c1)~(c12): Macroscopic morphology of Fe-PMSQ aerogel as the water / MTES molar ratio (h value) changes; (b) and (d) are the density and linear shrinkage rate of different samples, respectively; Figure 11 Fe-PMSQ aerogel prepared in Example 2: (a1)-(a6) SEM images; (b) C acid Effect on the average particle size of Fe-PMSQ aerogel; Figure 12 Fe-PMSQ aerogel prepared in Example 2: (a) C acid and (b) h value for the compressive strength (σ) of aerogel max ) and maximum compressive strain (ε max The impact of ) Figure 13 Cyclic compression of aerogel sample 17 at 40% strain: (a) Stress-strain curve of the first cycle (2.0 mm min) -1 (b1) 1.0 mm min and photos taken at 0%, 10%, 20%, 30%, 40% loading and 20%, 0% unloading moments; -1 (b2) 2.0mm min -1 Stress-strain curves for the 1st, 10th, 20th, 30th, 40th, 50th, and 60th cycles; the effect of the number of cycles at different compression rates on (c1) unrecoverable strain and (c2) dissipated energy; Figure 14 (a) Initial water contact angle θ and thermal conductivity λ of some Fe-PMSQ aerogel samples prepared in Example 2; (b) Evolution of θ and λ of sample 17 during 28 cycles of 60℃ / –35℃; (d1)~(d6) and (e1)~(e6) are visible light and infrared thermographic sequences of the upper surface of aerogel sample 17 without direct flame impact after being burned with an alcohol lamp for 0.0, 0.5, 1.0, 2.0, 5.0 and 15.0 min, respectively; (f1) and (f2) are photographs of the burned surface before and after burning for 15.0 min; in the figures, C = center temperature, M = maximum temperature; Figure 15 The changes in the center temperature and maximum temperature of the unexposed surface of aerogel sample 17 prepared in Example 2 with combustion time; Figure 16 The density of the aerogel samples prepared in Example 4 and Comparative Example 2 varies with h and g values. Figure 17 Compression stress-strain curves of aerogel composite felts A-1, A-2, A-3, B-1 and B-2 prepared in Example 5 and aerogel sample 17 prepared in Example 2; Figure 18 Cyclic compressive stress-strain curves of aerogel composite felt A-2 prepared in Example 5: (a) 40% strain, 2.0 mm / min; (b) During the corresponding cycle: red line (top) - the evolution of the thickness of the aerogel composite felt with the number of cycles; orange line (middle) - the evolution of energy loss per cycle with the number of cycles; blue line (bottom) - the evolution of peak stress with the number of cycles. Detailed Implementation

[0034] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and instruments described are commercially available unless otherwise specified.

[0036] In this embodiment of the invention, the stress-strain curve is obtained by compressing a sample with a diameter of 13-15 mm and a length of 20-28 mm at a rate of 2 mm / min using a universal testing machine.

[0037] Unless otherwise specified, the test environment conditions in the examples were 14.0±3.0℃ and relative humidity of 30%~60%.

[0038] In Example 2, the sample is labeled as “xy”, where x is the molar concentration of ammonia c (NH3·H2O) (in moles) and y is the volume of ammonia added V (NH3·H2O) (in microliters). In the example, the sample thickness in the alcohol lamp burning experiment was 7.86 mm.

[0039] Example 1: Preparation of Compressible Lightweight Fire-Resistant Aerogel Material Dissolve 0.024 g of FeCl3·6H2O in 3.0 mL of deionized water and vortex vigorously for about 30 s to obtain a light yellow FeCl3 stock solution. 3+ mass concentration ω(Fe) 3+ =8.0 mg / mL, pH 1.50~1.76.

[0040] First, 0.020 g CTAB and 2.0 mL of the above FeCl3 stock solution were dispersed in 48.8 mL of deionized water and magnetically stirred (400 rpm, 14.0±3.0 ℃) for 1.0 h.

[0041] Next, add 11.2 mL of MTES and continue magnetic stirring (400 rpm, 3.0 h, 14.0 ± 3.0 ℃). Fe 3+ Hydrolysis creates an acidic environment (pH ≈ 2.75), which in turn promotes the hydrolysis of MTES and causes Fe to covalently embed into the continuously growing colloidal framework.

[0042] Then, transfer 5.0 mL of the obtained sol into a 15 mL centrifuge tube (15.0 mm inner diameter), add a quantitative amount of 1.0–13.7 MNH3·H2O aqueous solution, vortex for about 10 s to mix, and adjust the pH to 5.5–9.0. The sol is then allowed to stand at room temperature (RT) until gelation occurs.

[0043] Then, the wet gel was aged at 14.0±3.0 °C for 36 h to consolidate the network.

[0044] Finally, after opening the lid, the product was placed in a convection oven (60 °C, 16 h) for atmospheric pressure drying to obtain Fe-PMSQ aerogel.

[0045] Table 1. Gelation parameters and atmospheric pressure drying results of wet gel in Example 1 Note: In Table 1, C NH3∙H2O = Molar concentration of ammonia, V NH3∙H2O = Volume of ammonia solution added, C base =Total alkali molar concentration in the sol. Gelation results: A-homogeneous gel mass; B-Heterogeneous gel mass (phase separation or precipitation occurs); C-Precipitation / sol bilayer; D-No gelation within 60.0 h (remains in sol state). Aerogel integrity: A-Intact aerogel (no cracks, uniform appearance); B-Intact aerogel but with macroscopic deformation; C-Sol leakage during normal pressure drying, aerogel cracking or becoming brittle.

[0046] As shown in Table 1 and Figure 1 As shown: In some embodiments of the present invention, C base At a pH of 6-11 mM, both the gelation results and the integrity of the aerogel are good. The pH at this range is approximately 6.5-8.2.

[0047] In some embodiments of the present invention, a pH of 6.6 to 7.2 can be used to prepare a uniform gel block, and the aerogel is intact after drying (without cracks and with a uniform appearance).

[0048] like Figure 2 As shown: when the pH value is below 6.75, the gelation time is relatively long, while under the condition of pH value of 7.0-7.5, the gelation time is as low as 0.5h.

[0049] like Figure 3 and Figure 4 As shown: The infrared image is located at 1020~1100 cm. -1 The strong and broad absorption peak is clearly attributed to the antisymmetric stretching vibration of the Si-O-Si bond. Meanwhile, at 2970 cm⁻¹... -1 and 1270 cm-1 The characteristic peaks that appear nearby correspond to the CH stretching vibration of methyl (-CH3) and the stretching vibration of the Si-C bond, respectively, proving that methyl groups are grafted into the network backbone. Figure 4 XPS fine spectral analysis provided quantitative information and evidence of chemical state at the atomic level. The O 1s peak showed that in addition to the standard Si-O-Si bonding (~532.8 eV), there were also metal-oxygen bonds; the FTIR and XPS data corroborated each other, proving that the aerogel network framework was composed of =Fe-O-Si≡, =Fe-O-Fe=, and ≡Si-O-Si≡, and that methyl groups were successfully grafted onto the framework.

[0050] like Figure 5 As shown, the aerogel of the present invention exhibits a three-dimensional network characteristic of interwoven and doped "kelp knot" shaped fibers and spherical nanoparticles, and the structure has a high porosity.

[0051] like Figure 6 As shown, the Fe-PMSQ aerogel prepared by this invention exhibits significant lightweight / ultra-low density and low linear shrinkage characteristics; its density is less than 100 mg / cm³. 3 In some preferred embodiments, the density is less than 70 mg / cm³. 3 The linear shrinkage rate is less than 10%, and in some preferred embodiments, it is less than 5%.

[0052] like Figure 7 As shown, the axial compression behavior of Fe-PMSQ aerogel is as follows: Figure 7 As shown in (a, b), the mechanical properties of the aerogel of this invention exhibit a three-stage characteristic. In the first stage, the material undergoes reversible elastic deformation; in the second stage, the curve shows a stress plateau or slow growth, reflecting flexibility and toughness. In the third stage, the stress increases exponentially with strain. This indicates that the highly branched Fe-PMSQ aerogel of this invention, with its "kelp knot + spherical" interdoped network structure, possesses excellent mechanical properties, combining good rigidity (high initial modulus), excellent toughness (long yield plateau), and high compressive strength (high stress in the densification stage), demonstrating superior overall performance; significantly better than traditional "pearl necklace" type silica networks.

[0053] like Figure 8 As shown, the aerogel of the present invention exhibits mechanical strength far superior to that of conventional aerogels while maintaining a porous structure, especially under high strain conditions (>60%), it has excellent energy absorption capacity and structural integrity.

[0054] Traditional SiO2 aerogels ("pearl necklace" type networks): composed of spherical particles connected by tiny "necks"; under stress, this structure concentrates stress highly in the fragile necks, making it prone to fracture and resulting in high brittleness and low strength. The Fe-PMSQ aerogel of this invention (highly branched network): Fe 3+ The introduction of this material promotes the formation of branching, coral-like structures. These structures eliminate the obvious "neck," resulting in thicker skeletal connections and allowing forces to be transmitted and dispersed more evenly throughout the three-dimensional network. Consequently, stress concentration effects are significantly reduced, requiring higher stresses to break the material, thus achieving a significant increase in compressive strength.

[0055] like Figure 9 As shown, the aerogel material of this invention exhibits excellent fatigue resistance. After up to 400 cycles of compression, the material does not suffer pulverization and its mechanical properties remain stable. It also possesses a significant "self-reinforcing" effect: the performance degradation after the first cycle eliminates internal weak points, making the material more reliable and stable in subsequent use. Furthermore, it exhibits excellent recoverability: the material does not undergo continuous collapse or creep during long-term use, maintaining effective thermal insulation thickness and buffer space. The Fe-PMSQ aerogel prepared by this invention not only has high static strength but also possesses dynamic mechanical reliability lacking in traditional brittle aerogels, meeting the long-term dynamic load requirements of new energy vehicles such as vibration and battery charging / discharging expansion.

[0056] Example 2: Preparation of Compressible Lightweight Fire-Resistant Aerogel Material Fe-PMSQ aerogels were synthesized via a two-step acid-base catalytic sol-gel method and atmospheric pressure drying. To ensure comparability between samples, the theoretical volume (V, containing MTES, CTAB, deionized water, and acid) of each MTES sol was fixed at 31.0 mL. Although the actual volume will shrink to varying degrees after mixing, this nominal volume is sufficient to prepare five parallel samples, ensuring statistical reliability.

[0057] (1) Preparation of FeCl3 solution: A quantitative amount of FeCl3·6H2O powder was placed in a beaker, deionized water was added, and the mixture was magnetically stirred at 400 rpm for 0.1 h to obtain a homogeneous, light yellow, transparent FeCl3 aqueous solution (mass concentration 8.0 mg / mL). -1 (pH 1.50~1.76).

[0058] (2) Preparation of CTAB / FeCl3 mixed aqueous phase: According to the formula in Table 2, 10.0 mg CTAB powder and 0.1~1.2 mL freshly prepared FeCl3 solution were added to 20.7~26.4 mL of deionized water and stirred at 400 rpm for 1.1 h at room temperature (21.0 ± 2.0 ℃) to obtain a homogeneous light yellow transparent mixed solution.

[0059] (3) Sol formation: Under continuous stirring, 3.765~9.505 mL of MTES was added to the above mixture, and the reaction was continued at 400 rpm at room temperature for 3.0 h to obtain a light yellow transparent MTES sol. Fe 3+ Extensive hydrolysis maintains the system at an acidic level (pH 2.50–3.50), promoting MTES hydrolysis and simultaneously introducing Fe into the PMSQ colloidal framework; at this point, the CTAB concentration in the sol, c(CTAB), is 0.885 mmol / L. -1 .

[0060] (4) Gelation and drying: Add 0.2 mL of 1.0 mol L to the sol at one time. -1 Mix rapidly with NH3·H2O at 400 rpm for approximately 30 s, and adjust the pH to 7.0–7.5. Then pour the sol into a Ø15.0 mm cylindrical mold and allow it to stand until gel formation. After aging at room temperature for 4.0 h (without aging solution), dry in an 80.0 ℃ forced-air drying oven for 16.0 h to obtain Fe-PMSQ aerogel.

[0061] Experiments have shown that when the acid concentration C in the sol... acid >0.955 mmol / L -1 During the subsequent atmospheric pressure drying process, defects such as poor gelation, excessive densification, and internal cavities occurred.

[0062] The thermal conductivity of aerogel samples 1, 9 and 17 at an average temperature of 25 °C were 34.9 mW / (m·K), 33.9 mW / (m·K) and 32.2 mW / (m·K), respectively.

[0063] Comparative Example 1: The experimental procedure was basically the same as in Example 2, except that 2.0 mmol L was used. -1 Acetic acid (AA) and 100.0 mmol L -1 Using hydrochloric acid (HCl) as the acid catalyst, replacing the FeCl3 solution, PMSQ aerogels were prepared following the same procedure. The corresponding sample number is 1. AA 1 HCl 9 AA 9 HCl Detailed parameters are shown in Table 2.

[0064] Table 2 Formulation and integrity of aerogel materials in Example 2 / Comparative Example 1 Note: In Table 2, V acid = The volume of FeCl3, acetic acid, or hydrochloric acid aqueous solution added; V NH3∙H2O = The volume of the added NH3·H2O aqueous solution; C MTES = MTES concentration in the sol; C acid = Acid concentration in the sol (i.e., FeCl3, acetic acid, or HCl); h = Molar ratio of hydrolyzed water to MTES, i.e., n(H2O) / n(MTES). The absence of a superscript symbol in the sample number indicates the use of FeCl3; AA and HCl represent acetic acid and hydrochloric acid, respectively. Aerogel integrity: A - Intact, no cracks, no significant difference in dimensions; B - No cracks, but corners may chip when removed from the centrifuge tube; C - Aerogel firmly adheres to the centrifuge tube wall, internal cavities appear after drying at normal pressure.

[0065] like Figure 10 As shown: (a) and (c) are partial sample photographs; (b) and (d) are density and linear shrinkage rate tests of different samples prepared in Example 2, respectively; it can be seen that when the FeCl3 concentration C acid High-quality Fe-PMSQ aerogels with intact structure, low density, and low shrinkage can be prepared at a water / MTES molar ratio (h value) of 0.6–1.0 mM and 45–60 mM, with a linear shrinkage rate of less than 10% and a density of less than 100 mg / cm³. 3 .

[0066] like Figure 11 As shown: C further corroborates this. acid At a concentration of 0.6–1.0 mM, a large and well-structured "kelp knot" framework can be formed. In particular, at a concentration of 0.80–0.96 mM, the average particle size of the "kelp knot" framework is 1450–1540 nm. Its coarse and tough neck region connection provides the microstructure basis for the strong mechanical properties of the aerogel.

[0067] like Figure 12 As shown, the Fe-PMSQ aerogel material prepared by this invention possesses both high strength and high toughness. Its compressive strength (up to 1.6 MPa) and ultra-large deformation capacity (strain > 80%) solve the problems of traditional aerogels being "brittle" and "fragile".

[0068] like Figure 13 As shown, aerogel sample 17 exhibits excellent mechanical stability and fatigue resistance. At 40% strain and 60 cycles, after initial adjustment, the material's peak stress and energy dissipation (Emax) are significantly reduced.L It quickly stabilizes, exhibiting excellent energy rebound and durability. The unrecoverable strain increment generated in each cycle approaches zero with the increase of the number of cycles, and it can basically return to its original state after repeated compression.

[0069] like Figure 14 As shown, the Fe-PMSQ aerogel material prepared by this invention exhibits significant advantages in thermal insulation and high-temperature fire resistance. Its thermal conductivity at room temperature is below 35 mW / (m·K), demonstrating excellent thermal insulation performance. The material also possesses excellent hydrophobicity, with a water contact angle of 105~145°, ensuring stability in humid environments. In extreme temperature tests, the material exhibits strong weather resistance: after 28 cycles of heating and cooling from -35°C to 60°C, its thermal conductivity and hydrophobic angle remain stable. Regarding fire resistance, after being directly burned by an alcohol lamp flame for 15 minutes, the overall structure of the material remains intact, without melting or burning, and the highest temperature on the unexposed surface is effectively suppressed.

[0070] like Figure 15 As shown: Under continuous burning with an alcohol lamp flame (approximately 500~600℃), the center temperature of the material's unexposed side stabilized after 3 minutes, and the center temperature was effectively suppressed below 200℃ after 16 minutes. This indicates that heat is extremely difficult to penetrate the material, demonstrating that it possesses extremely low high-temperature thermal conductivity and uniform thermal insulation performance, with no localized thermal bridging effect. It also demonstrates the structural integrity of the material under flame impact, showing no collapse or failure.

[0071] Example 3: Preparation of Compressible Lightweight Fire-Resistant Aerogel Material Fe-PMSQ aerogels were synthesized via a two-step acid-base catalytic sol-gel method and atmospheric pressure drying. To ensure comparability between samples, the theoretical volume (V, containing MTES, CTAB, deionized water, and acid) of each MTES sol was fixed at 31.0 mL. Although the actual volume will shrink to varying degrees after mixing, this nominal volume is sufficient to prepare five parallel samples, ensuring statistical reliability.

[0072] (1) Preparation of FeCl3 solution: A quantitative amount of FeCl3·6H2O powder was placed in a beaker, deionized water was added, and the mixture was magnetically stirred at 400 rpm for 0.1 h to obtain a homogeneous, light yellow, transparent FeCl3 aqueous solution (mass concentration 8.0 mg / mL). -1 (pH 1.50~1.76).

[0073] (2) Preparation of CTAB / FeCl3 mixed aqueous phase: According to the formulations of samples 6, 7, 8 and 9 in Table 2, 10.0 mg of CTAB powder and 0.7~1.0 mL of freshly prepared FeCl3 solution were added to 24.4~24.7 mL of deionized water, and stirred at 400 rpm for 1.1 h at 8.0±2.0℃, 12.0±2.0℃, 28.0±2.0℃ and 32.0±2.0℃ respectively to obtain a homogeneous light yellow transparent mixed solution.

[0074] (3) Sol formation: Under continuous stirring, 5.614 mL of MTES was added to the above mixture, and the reaction was continued for 3.0 h at the same temperature and 400 rpm as in step (2) to obtain a light yellow transparent MTES sol. Fe 3+ Extensive hydrolysis maintains the system at an acidic level (pH 2.50–3.50), promoting MTES hydrolysis and simultaneously introducing Fe into the PMSQ colloidal framework; at this point, the CTAB concentration in the sol is C. (CTAB) = 0.885 mmol L -1 .

[0075] (4) Gelation and aging: Add 0.2 mL of 1.0 mol L to the sol at one time. -1 Mix NH3·H2O rapidly at 400 rpm for approximately 30 seconds, and adjust the pH to 7.0–7.5. Then pour the sol into a Ø15.0 mm cylindrical mold and allow it to stand until gel formation. Finally, age the gel at 5.0–60.0℃ for 1–120 h (without aging solution).

[0076] (5) Drying: The gel was placed in an 80.0℃ forced-air drying oven and dried for 16.0 h to obtain Fe-PMSQ aerogel.

[0077] The experimental results of Example 3 showed that only when the hydrolysis temperature was 10~30℃ and the hydrolysis time was 0.5~6 h could the obtained Fe-PMSQ aerogel form a block without cracks and with good mechanical properties. When the hydrolysis temperature was below 10℃ or above 30℃, the obtained Fe-PMSQ aerogel either cracked, had a shrinkage rate greater than 15%, or had poor mechanical properties, making it impossible to carry out subsequent mechanical, thermal insulation and fire resistance performance studies.

[0078] Experiments revealed a dependence between aging and settling temperature and time: 20–168 h for temperatures of 10–18°C; 3–120 h for temperatures of 18–30°C; 2–96 h for temperatures of 30–40°C; and 1–48 h for temperatures of 40–50°C. Only under these specific aging and settling conditions can Fe-PMSQ aerogel blocks with crack-free properties, low shrinkage, strong mechanical properties, and high thermal insulation / fire resistance be formed. Exceeding these conditions results in Fe-PMSQ aerogels with either poor mechanical properties or cracking and high shrinkage.

[0079] Example 4: Preparation of Compressible Lightweight Fire-Resistant Aerogel Material Fe-silica aerogels were synthesized via a two-step acid-base catalytic sol-gel method and atmospheric pressure drying. To ensure comparability between samples, five parallel samples were prepared for each sol to guarantee statistical reliability.

[0080] (1) Preparation of surfactant / Fe 3+ Salt mixed aqueous solution: According to the formula in Table 3, add a certain amount of Fe 3+ Salt was placed in a beaker, and 26.8 mL of deionized water was added. The mixture was magnetically stirred at 400 rpm for 0.1 h. Then, a measured amount of surfactant was added, and the mixture was stirred at 400 rpm for 1.0 h at room temperature (22.0 ± 2.0 °C) to obtain a homogeneous surfactant / Fe mixture. 3+ Mixed aqueous solution.

[0081] (2) Sol formation: Under continuous stirring, the above surfactant / Fe 3+ A measured amount of silicon source was added to the mixed aqueous solution, and the reaction was continued at room temperature and 400 rpm for 3.0 h to obtain a light yellow sol.

[0082] (3) Gelation and aging: Add 0.2 mL of 1.0 mol L to the sol at one time. -1 Mix NH3·H2O rapidly at 400 rpm for approximately 30 seconds, and adjust the pH to 7.0–7.5. Then, pour the sol into a Ø15.0 mm cylindrical mold and allow it to stand until gel forms. Finally, age the gel at room temperature for 24 hours.

[0083] (4) Hydrophobic modification (not mandatory, but required when using mixed silicon sources): Place the above gel in a trimethylchlorosilane / n-hexane (volume ratio 1:9) modification solution and heat at 40°C for 12 h. Remove the gel from the hydrophobic modification solution and place it in n-hexane, then heat at 40°C for 12 h. Discard the liquid phase. Repeat the above operation 0-3 times to obtain the modified gel.

[0084] (5) Drying: Place the gel obtained in step (3) or the modified gel obtained in step (4) in an 80.0℃ drying oven for 24.0 h to obtain Fe-silica aerogel.

[0085] Comparative Example 2: The experimental steps were basically the same as in Example 4, except that the amount of deionized water added was changed. The h values ​​of the controlled formulation were 40.0±0.1, 50.0±0.1, 60.0±0.1 and 70.0±0.1, and the g values ​​were 0.0, 5.0±0.1, 10.0±0.1, 15.0±0.1 and 20.0±0.1, respectively. Fe-silica aerogels were prepared according to the same procedure. Detailed parameters are shown in Table 4.

[0086] The experimental results of Example 4 and Comparative Example 2 were characterized using the analytical methods described above, and the following findings were made: (1) The average particle sizes of Fe-silica aerogel samples 1, 2, 3, and 4 were 1085 nm, 886 nm, 682 nm, and 588 nm, respectively. It is evident that increasing the amount of surfactant F127 added to the sol is beneficial for obtaining Fe-silica aerogels with smaller particle sizes. Aerogel samples 1, 2, and 3 all exhibited good mechanical properties and were crack-free. However, when the amount of F127 added was 0.06 g, the prepared Fe-silica aerogel cracked / could not form a block. Therefore, the content of surfactant F127 in the sol should be less than 0.04 g.

[0087] (2) For the silicon source composite system of MTMS and TMOS, when the g value is 5.0 and 9.9, the Fe-silica aerogel samples 5 and 6 are intact and without cracks; while when the g value is greater than or equal to 15.1, the Fe-silica aerogel samples 7 and 8 have a small amount of chipping at the edges, but the mechanical properties are still acceptable.

[0088] (3) For the silicon source composite system of MTES and TEOS, when the g value is 5.1~15.1, the prepared Fe-silica aerogel samples 9, 10 and 11 are intact and without cracks; when the g value is 19.6, the prepared Fe-silica aerogel sample 12 has a small amount of chipping at the corners, but the mechanical properties are still acceptable; when the g value is 21.1, the prepared Fe-silica aerogel sample 13 cracks and cannot be formed into a block.

[0089] (4) For different methylalkoxysilane and tetrafunctional silicon source composite systems, when they are mixed in a volume ratio of (100~80):(0~20), the Fe-silica aerogels prepared have good mechanical properties and good bulking properties.

[0090] (5) If a composite silicon source is used to prepare Fe-silica aerogel, when the h value is 45~65, the compressive strength of Fe-silica aerogel increases with the increase of g value, but its density and linear shrinkage rate also increase with the increase of g value.

[0091] (6) For the silicon source composite system of MTES and water glass, when the g value is 4.3, both the unmodified and hydrophobically modified Fe-silica aerogels (samples 14 and 14-M) have complete and crack-free morphologies, and their densities are 118 mg / cm³, respectively. 3 and 112 mg / cm 3 The compressive strengths were 1.12 MPa and 1.15 MPa, respectively. In contrast, when the g-value was 10.0, the unmodified Fe-silica aerogel (sample 15-U) cracked and could not form a bulk mass, while the hydrophobically modified Fe-silica aerogel (sample 15) had a complete, crack-free morphology. Therefore, when the silicon source is a mixed silicon source containing a tetrafunctional silicon source, and the volume fraction of the tetrafunctional silicon source is greater than 5% of all silicon sources, the gel needs hydrophobic modification to obtain Fe-silica aerogels with good bulk properties and mechanical properties.

[0092] (7) For the silica sol system, the atmospheric pressure drying process can only produce cracked Fe-silica aerogels that cannot be formed into blocks. When silica sol is compounded with MTES and the g value is less than 10%, the Fe-silica aerogel (sample 17) has a complete and crack-free morphology and high mechanical properties.

[0093] like Figure 16 As shown, when the g value is between 0 and 20% and the h value is between 40 and 70, the density of the prepared aerogel is between 80 and 150 mg / cm³. 3 Between, and when the g value does not exceed 10%, the density does not exceed 120 mg / cm³. 3 When the g value does not exceed 5%, the density does not exceed 110 mg / cm³. 3 .

[0094] Table 3 Formulation and integrity of aerogel materials in Example 4 Note: C acid = Acid concentration in the sol (i.e., FeCl3, Fe(NO3)3, Fe(SO4)3 or NH4Fe(SO4)2); g = Volume fraction of all silicon sources with four functionalities; h= Molar ratio of hydrolyzed water to all silicon sources. Aerogel integrity: A - Intact, no cracks, no significant difference in size between the top and bottom, high mechanical properties; B - No cracks, but corners may chip when removed from centrifuge tubes, but mechanical properties are still acceptable; C - Aerogel fragmented, unable to form blocks or firmly adhere to the centrifuge tube wall, internal cavities appear after drying at normal pressure. Except for samples 14-M and 15-U, the table shows... g All aerogel samples with a value greater than or equal to 5.0 underwent hydrophobic modification and solvent exchange steps. Sample 14-M underwent both hydrophobic modification and hydrophobic exchange steps, while sample 15-U did not.

[0095] Table 4. Formulation and integrity of aerogel materials in Comparative Example 2 of Example 4 Remark: C acid = The concentration of Fe(NO3)3 in the sol; g = TEOS volume fraction of all silicon sources; h = Molar ratio of hydrolyzed water to all silicon sources. Aerogel integrity: A - Intact, no cracks, no significant difference in size between the top and bottom, high mechanical properties; B - No cracks, but corners may chip when removed from centrifuge tubes, but mechanical properties are still acceptable; C - Aerogel fragmented, unable to form blocks or firmly adhere to the centrifuge tube wall, internal cavities appear after drying at normal pressure. All aerogel samples in the table have undergone hydrophobic modification and solvent exchange steps.

[0096] Example 5: Preparation of Compressible Lightweight Fire-Resistant Aerogel Composite Felt Fe-PMSQ aerogel composite felt was synthesized via a two-step acid-base catalytic sol-gel method and a drying process. In this example, five parallel samples were prepared using both atmospheric pressure drying and supercritical CO2 drying processes to ensure data reliability.

[0097] (1) Sol formation: MTES sol was prepared according to the formulation (scaled up 5 times) and process of sample 17 in Table 2. In addition to CTAB, equal amounts of F127 and P123 can also be used as surfactants in the formulation.

[0098] (2) Gelation: Add 1.0 mL of 1.0 mol L to the sol. -1 Mix NH3·H2O rapidly at 400 rpm for about 30 seconds, and adjust the pH to 7.0~7.5. Then, impregnate the silica sol into the interior of a glass fiber mat with a thickness of 3 mm and a diameter of 150 mm through osmosis, let it stand and age at room temperature for 4.0 h (without aging solution) to form a gel composite mat.

[0099] (3) Drying: The gel composite felt was placed in an 80.0 ℃ drying oven for 24.0 h to obtain Fe-PMSQ aerogel composite felt A; the samples with added surfactants CTAB, F127 and P123 were recorded as A-1, A-2 and A-3, respectively.

[0100] The gel composite felt was placed in a supercritical CO2 drying vessel, the vessel was sealed, and CO2 was introduced to dry the gel composite felt at 50℃ and 9.0 MPa for 12 h to obtain Fe-PMSQ aerogel composite felt B; aerogel composite felts prepared by adding surfactants CTAB and F127 were B-1 and B-2, respectively.

[0101] The performance of the composite felt prepared in Example 5 was tested, and the results showed that the aerogel composite felt prepared by either atmospheric pressure drying or supercritical drying process had a complete and crack-free morphology.

[0102] like Figure 17 As shown, aerogel composite felt A-1 exhibits soft mechanical properties: even at 80% compressive strain, its stress is only 0.018 MPa. In contrast, aerogel composite felts A-2 and A-3 exhibit stresses of 0.860 MPa and 0.634 MPa, respectively, at 80% compressive strain. This demonstrates that even with the same sol formulation and drying process, the mechanical properties (soft-to-tough transition) of aerogel composite felt A can be significantly controlled by adjusting the type of surfactant in the formulation. Furthermore, aerogel composite felts A-2 and A-3 show higher compressive stresses at the same compressive strain compared to aerogel sample 17, reflecting the synergistic effect between the aerogel material and the fiber felt substrate, resulting in stronger mechanical properties. Aerogels B-1 and B-2, prepared using a supercritical drying process, also exhibit strong mechanical properties.

[0103] The aerogel composite felt A-1 has a thickness of 2.1±0.2 mm and a density of 155±10 kg / m³. 3 The average particle size (aerogel particles) is 550±40 nm, and the thermal conductivity at an average temperature of 25℃ is 32.8 mW / (m·K). The thickness of aerogel composite felt A-2 is 2.2±0.2 mm, and the density is 148±10 kg / m³. 3 The average particle size is 450±40 nm, and the thermal conductivity at an average temperature of 25℃ is 31.3 mW / (m·K). The thickness of the aerogel composite felt A-3 is 2.3±0.2 mm, and the density is 142±10 kg / m³. 3 The average particle size is 370±40 nm, and the thermal conductivity at an average temperature of 25℃ is 30.2 mW / (m·K).

[0104] The aerogel composite felt B-1 has a thickness of 2.5±0.2 mm and a density of 130±10 kg / m³. 3 The average particle size is 120±20 nm, and the thermal conductivity at an average temperature of 25℃ is 20.6 mW / (m·K). The thickness of the aerogel composite felt B-2 is 2.6±0.2 mm, and the density is 125±10 kg / m³. 3 The average particle size is 160±20 nm, and the thermal conductivity at an average temperature of 25℃ is 20.2 mW / (m·K).

[0105] like Figure 18 As shown, aerogel composite felt A-2 exhibits excellent structural stability and fatigue resistance in cyclic compression tests at 40% strain. Initially, the material thickness decreases slightly, and stiffness drops. After the initial stage, the material enters a highly stable state. Peak stress and energy loss rate remain essentially constant. Energy loss decreases rapidly and remains at a low level. The composite felt possesses significant advantages such as rapid stabilization, good resilience, and high durability.

[0106] The aerogel composite felts A and B prepared in Example 5 both have a density (180~250 kg / cm³) that is higher than that of commercially available aerogel insulation sheets. 3 The thermal conductivity of aerogel composite felt B is lower than that of commonly available aerogel insulation sheets (15~25 mW / (m·K)), making it suitable for high-end applications such as thermal barrier protection for power battery systems in new energy vehicles and thermal insulation in aerospace. Aerogel composite felt A has a slightly higher thermal conductivity, but due to its excellent compression and compression-resilience properties, it is suitable for civilian applications such as fireproofing and thermal insulation in buildings.

[0107] In summary, this invention provides a compressible lightweight fire-retardant aerogel material and its preparation method. The aerogel material is prepared via a sol-gel method and a drying process: using FeCl3 aqueous solution as an acid catalyst and reactant, trace amounts of Fe are released simultaneously during the catalytic hydrolysis of the silicon source. 3+ Hydrolysis is incorporated into the polymer network framework, and the final product is obtained by gelation, aging and drying under normal pressure. The aerogel material network framework of the present invention is a branched polymer network framework composed of hybrid bonds of ≡Si-O-Si≡, =Fe-O-Si≡ and =Fe-O-Fe≡.

[0108] The preparation method of this invention is green and environmentally friendly, requiring no organic solvents or expensive supercritical drying equipment, and is low in cost and easy to scale up. The resulting aerogel material exhibits excellent comprehensive properties: its density is extremely low (50~150 kg / m³). 3Despite its high compressive strength (stress reaching 0.10~2.0 MPa at 80% strain) and high resilience (maximum stress reduction of less than 50% after 150~400 compression cycles at 40% strain), this material possesses a low thermal conductivity of 15~35 mW / (m·K) and a high water contact angle of 100~155°. It exhibits excellent hydrophobicity and fire resistance, and can withstand temperatures above 200℃ for extended periods while maintaining structural integrity under flame impact at 1200℃. This material is particularly suitable for applications with extremely high space and safety requirements, such as thermal barrier protection for new energy vehicle power battery systems, aerospace thermal insulation, and building fireproofing and insulation, demonstrating enormous potential for industrial application.

[0109] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a compressible lightweight fire-retardant aerogel material, characterized in that, It is prepared by the sol-gel method and drying process, specifically including the following steps: S1. Dissolve 0.01~0.20 parts of surfactant in 99.60~99.98 parts of deionized water, then add 0.01~0.20 parts of Fe. 3+ Salts are mixed evenly to prepare an iron salt / surfactant aqueous solution; A silicon source solution was prepared by mixing methylalkoxysilane with a tetrafunctional silicon source at a volume ratio of (100~80): (0~20) and stirring continuously. S2. Preparation of silica sol: 70-90 parts of the iron salt / surfactant aqueous solution and 10-30 parts of the silicon source are mixed and then hydrolyzed at 10-30°C with stirring for 0.5-6.0 h to form silica sol; The mixing method in step S2 is as follows: the iron salt / surfactant aqueous solution is added dropwise to the silicon source solution, or the silicon source solution is added dropwise to the iron salt / surfactant aqueous solution. S3. Preparation of silica gel: Add the alkaline catalyst to the silica sol obtained in step S2, stir for 0.1~5 min, and control the pH to 6.5~8.0; pour into a mold and age at 10℃~50℃ for 1~168 h to obtain silica gel; S4. The silica gel described in step S3 is dried in an environment of 40~110℃ for 6~96 h to obtain a compressed lightweight fire-resistant aerogel material.

2. The preparation method of the compressible lightweight fire-retardant aerogel material according to claim 1, characterized in that, In step S2, the molar ratio (h value) of hydrolyzed water to silicon source is 45~65; In step S2, in the silica sol, Fe 3+ Salt concentration (C) acid The concentration is 0.4~1.0 mM, preferably 0.60~0.96 mM; In step S3, the aging and settling process, the settling temperature and settling time are dependent on each other: when the settling temperature is 10~18℃, the settling time is 20~168 h; when the settling temperature is 18~30℃, the settling time is 3~120 h; when the settling temperature is 30~40℃, the settling time is 2~96 h; when the settling temperature is 40~50℃, the settling time is 1~48 h. In step S3, the alkaline catalyst is one or a combination of ammonia, ethylenediamine, triethylamine, and pyridine. In step S3, the pH is adjusted to 6.5-8.0 by adding an alkaline catalyst; In step S3, the pH is adjusted to control the total alkali molar concentration in the sol to be 6-14 mM, preferably 7-10 mM.

3. The method for preparing the compressible lightweight fire-retardant aerogel material according to claim 1 or 2, characterized in that, It also includes a silica gel modification step: placing the silica gel in a hydrophobic modification liquid and heating it in an environment of 10℃~60℃ for 6~24 h; then, removing the silica gel, exchanging the solvent, and discarding the liquid phase to obtain the modified silica gel.

4. The method for preparing the compressible lightweight fire-retardant aerogel material according to claim 1, characterized in that, The surfactant is selected from one or a combination of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, polyoxyethylene-polyoxypropylene triblock copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer; and / or, The Fe 3+ The salt is selected from one or a combination of ferric chloride, ferric sulfate, ferric nitrate, and ferric ammonium sulfate and their hydrates; The methylalkoxysilane is one or both of methyltrimethoxysilane and methyltriethoxysilane; The tetrafunctional silicon source is one or a combination of methyl orthosilicate, ethyl orthosilicate, water glass, and silica sol.

5. The compressible lightweight fire-retardant aerogel material prepared by the method according to any one of claims 1-4, characterized in that, The aerogel network framework has a branched structure, including framework particles and neck regions connecting the framework particles; The skeletal particles include a structure of inter-doped kelp-like or coral-like particles and spherical particles, with the skeletal particles connected by neck regions. The average particle size of the skeletal particles is 100~3500 nm.

6. The compressible lightweight fire-retardant aerogel material according to claim 5, characterized in that, The density of the aerogel material is 50~150 kg / m³. 3 The water contact angle is 100°~155°; and / or, The aerogel material further includes a precipitated phase embedded in the network framework; and / or, The aerogel network framework particles are composed of =Fe-O-Si≡, =Fe-O-Fe= and ≡Si-O-Si≡ networks, with methyl groups grafted into the network framework.

7. The compressible lightweight fire-retardant aerogel material according to claim 5, characterized in that, The aerogel material has a compressive strength of 0.3~1.6 MPa and a maximum compressive strain of ≥70%.

8. A fire-resistant aerogel composite felt, characterized in that, The product is prepared by impregnating the fiber felt with the silica sol as described in any one of claims 1-7, followed by gelation and drying. The thermal conductivity of the aerogel composite felt at 25°C is ≤40 mW / (m·K), preferably ≤35 mW / (m·K); The density of the aerogel composite felt is 50~200 kg / m³. 3 .

9. The fire-retardant aerogel composite felt according to claim 8, characterized in that, The preparation method includes the following steps: adding an alkaline catalyst to the silica sol obtained in step S2, stirring for 0-5 min, and adjusting the pH to 6.5-8.5; then impregnating the silica sol into the fiber felt through osmosis or negative pressure; placing it at 10℃-50℃ for 1-168 h to obtain silica gel felt; and drying it to obtain the aerogel composite felt. The fiber mat is selected from glass fiber, pre-oxidized fiber and ceramic fiber.

10. The application of the compressible lightweight fire-retardant aerogel material prepared by the method according to any one of claims 1-4. Or the application of the compressible lightweight fire-retardant aerogel material as described in any one of claims 5-7. Or the application of the fire-retardant aerogel composite felt according to any one of claims 8-9, characterized in that, It is applied in the fields of thermal barrier protection for power battery systems of new energy vehicles, aerospace thermal insulation, and building fire protection and insulation.

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