Fiber-reinforced silicon dioxide aerogel material and preparation method thereof

Abstract

The invention discloses a fiber-reinforced silicon dioxide aerogel material and a preparation method thereof, and belongs to the technical field of inorganic functional materials. In order to solve the problems that the existing silicon dioxide aerogel is too large in thickness and insufficient in temperature resistance and light weight level, the fiber-reinforced silicon dioxide aerogel material is prepared by adopting a short cut oxide fiber wet suction filtration forming process and introducing a nano-silica sol dipping gel and a supercritical drying process. Ultrathin forming can be achieved, and the composite material has low density and high-temperature stability and is suitable for thermal protection application of new energy batteries and other scenes with high safety requirements.

Description

Technical Field

[0001] This invention relates to a fiber-reinforced silica aerogel material and its preparation method, belonging to the field of inorganic functional materials technology. Background Technology

[0002] With the advancement of global "dual-carbon" goals, the demand for high-energy-density, long-life new energy batteries for new energy vehicles, energy storage systems, and 3C electronic devices has surged. Lithium-ion batteries, due to their high specific capacity and low self-discharge rate, have become the mainstream technology. However, batteries generate significant heat during charging and discharging, and are prone to thermal runaway when affected by internal short circuits, overcharging / over-discharging, mechanical impacts, or external high temperatures. This manifests as a sudden rise in local temperature (up to 800-1000℃), the emission of flammable gases, and chain reactions, seriously threatening equipment and personnel safety. Therefore, efficient thermal protection and mechanical buffering have become one of the core requirements for new energy battery pack design.

[0003] Currently, mainstream lithium battery insulation materials mainly include foam, ceramic fiber felt, and mica sheets. Although they possess certain insulation properties, they suffer from problems such as large thickness, high density, and insufficient insulation capacity. They cannot simultaneously meet the comprehensive requirements of lightweighting, ultra-thinness, high insulation, and impact resistance, thus hindering the safe application of high-energy-density batteries. Aerogel materials are porous solid materials formed by the accumulation of nanoscale particles. They are currently used as insulation materials in some lithium-ion batteries. However, with the continuous increase in battery energy density, the requirements for insulation layer thickness, temperature resistance, and lightweighting are constantly increasing. Existing aerogel materials are insufficient to meet the insulation needs of next-generation lithium-ion batteries. Summary of the Invention

[0004] The purpose of this invention is to propose a lightweight, high-temperature resistant fiber-reinforced silica aerogel material and its preparation method, so as to solve the technical problems of existing silica aerogels having a relatively thick molding thickness, insufficient temperature resistance, and limited lightweight level, and to achieve ultra-thin molding, high temperature resistance stability and low density at the same time, so as to meet the thermal protection application requirements of high energy density new energy batteries.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for preparing a fiber-reinforced silica aerogel material includes the following steps: 1) Inorganic fibers are mixed with an adhesive solution and dispersed to obtain fiber slurry; 2) The fiber slurry is placed in a filtration device for vacuum filtration to obtain a wet fiber layer; 3) Dry the wet fiber layer to obtain a dry fiber layer; 4) Place the dry fiber layer in a flat mold and add a silica sol mixture to completely immerse the fiber to obtain a fiber impregnated material; 5) After the flat mold is closed, it is left to stand at room temperature and then heated. After cooling, the mold is opened to obtain wet gel. 6) The wet gel is placed in a solvent for displacement to obtain the displaced gel; 7) The replaced gel is subjected to supercritical drying to obtain fiber-reinforced silica aerogel.

[0007] Furthermore, in step 1), the inorganic fibers are oxide fibers, and the oxides include quartz, mullite, etc. , One of the following: the inorganic fiber has a diameter of 0.3~8μm and a length of 5~10mm; the adhesive is one or both of polyvinyl alcohol (PVA) or cellulose, with a mass fraction of 5%~20%; the solvent of the solution is water or ethanol.

[0008] Furthermore, the dispersion rate in step 1) is 200~400 r / min.

[0009] Furthermore, the filtration time in step 2) is 0.5~1h.

[0010] Furthermore, in step 3), the drying temperature is 80~120℃ and the drying time is 2~4h.

[0011] Further, in step 4), the silica sol mixture includes silica sol and acid; the silica sol contains 5%–25% particles with a particle size of 3–30 nm; the acid used is HCl. , One of them; the pH of the mixed solution is 6-8.

[0012] Further, in step 5), the mixture is left to stand at room temperature for 24-36 hours; then heated to 80-100°C and held for 48-72 hours.

[0013] Further, in step 6), the wet gel is placed in an ethanol solution for solvent replacement. The volume of the ethanol solution is 20 to 25 times the volume of the wet gel itself, and the volume of the organic solution is 15 to 25 times the volume of the hydrogel. The replacement time is 7 to 10 days.

[0014] Further, in step 7), the drying solvent is... The drying pressure is 5~10MPa.

[0015] A fiber-reinforced silica aerogel material is prepared by the above-described method.

[0016] The present invention has achieved the following beneficial effects.

[0017] 1. This invention constructs an ultra-thin fiber-reinforced skeleton by wet filtration of short-cut oxide fibers, with precise thickness control, achieving stable molding of less than 0.5 mm, significantly overcoming the problem of limited thickness in existing aerogel products.

[0018] 2. This invention uses nano-silica sol as a silicon source and combines it with supercritical drying process to make the resulting aerogel small in pore size, high in porosity and low in density, while having excellent thermal insulation performance and structural integrity.

[0019] 3. This invention, through the synergistic design of fiber reinforcement and inorganic oxide system, enables aerogel materials to maintain good thermal stability above 1000℃, making them suitable for high-temperature protection scenarios.

[0020] 4. This invention uses water or ethanol as the main solvent system, avoiding the complex hydrolysis process and high-salt wastewater problems caused by the orthosilicate route, simplifying the process and making it environmentally friendly.

[0021] 5. The density of the aerogel material obtained by this invention is 0.15~0.25. The fiber weight ratio is 30%~40%; the aerogel material is 0.2~0.4mm thick, and has the characteristics of being lightweight, ultra-thin and high temperature resistant. It is suitable as a high-performance thermal protection material for new energy batteries and energy storage systems, and has good engineering application value. Attached Figure Description

[0022] Figure 1 Here is a photograph of the fiber-reinforced silica aerogel material prepared in Example 1; Figure 2 Here is a photograph of the fiber-reinforced silica aerogel material prepared in Example 2; Figure 3 The image shows the thickness test result of the fiber-reinforced silica aerogel material prepared in Example 3. Detailed Implementation

[0023] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, detailed descriptions are provided below through embodiments.

[0024] Example 1.

[0025] (1) Select quartz short chopped fibers with a diameter of 0.3 μm and a length of 5 mm, place them in a dispersing machine for dispersing, use water as the solvent, add 5% PVA adhesive by weight of fiber to the solvent before dispersing, and the dispersing rate is 200 r / min.

[0026] (2) The dispersed fiber slurry was placed in a Buchner funnel for filtration. The filtration time was 0.5 minutes to obtain ultra-thin wet fibers.

[0027] (3) Dry the ultra-thin wet fiber at a temperature of 80°C for 2 hours.

[0028] (4) Place the dried ultrathin fiber layer into a flat mold and add a mixed sol solution until the fiber is completely submerged. The mixed sol solution is composed of silica sol and acid. The silica sol solution has a particle ratio of 5%, a particle size of 3 nm, a pH of 9, and an acid of HCl. The final pH of the mixed solution is controlled at 6.

[0029] (5) After the mold is closed, it is left to stand at room temperature for 24 hours, then placed at 80°C and heated for 48 hours. After cooling, the mold is opened to obtain wet gel.

[0030] (6) Place the wet gel in an ethanol solution with a volume of 20 times its own to perform solvent replacement. The replacement time is 7 days, and the volume of the organic solution during replacement is 15 times the volume of the hydrogel.

[0031] (7) The replaced hydrogel was subjected to supercritical drying using a drying solvent of [missing information]. The drying pressure is 5 MPa, which yields a lightweight, high-temperature resistant, ultra-thin fiber-reinforced silica aerogel material.

[0032] The aerogel material was tested and found to be 0.4 mm thick with a density of 0.20. .

[0033] Example 2.

[0034] (1) Select mullite short chopped fibers with a diameter of 8μm and a length of 10mm, place them in a dispersing machine for dispersing, select ethanol as the solvent, add cellulose binder with a fiber mass fraction of 20% to the solvent before dispersing, and the dispersing rate is 400r / min.

[0035] (2) The dispersed fiber slurry was placed in a Buchner funnel for filtration for 1 hour to obtain ultra-thin wet fibers.

[0036] (3) Dry the ultra-thin wet fiber at a temperature of 120°C for 4 hours.

[0037] (4) Place the dried ultrathin fiber layer into a flat mold and add a mixed sol solution until the fiber is completely submerged. The mixed sol solution consists of silica sol and acid. The silica sol solution contains 25% particles with a particle size of 30 nm and a pH of 14. The acid is... The final pH of the mixed solution was controlled at 8.

[0038] (5) After the mold is closed, it is left to stand at room temperature for 36 hours, then placed at 100°C and heated for 72 hours. After cooling, the mold is opened to obtain wet gel.

[0039] (6) Place the wet gel in an ethanol solution with a volume of 25 times its own to perform solvent replacement. The replacement time is 10 days, and the volume of the organic solution during replacement is 25 times the volume of the hydrogel.

[0040] (7) The replaced hydrogel was subjected to supercritical drying using a drying solvent of [missing information]. The drying pressure is 10 MPa, which yields a lightweight, high-temperature resistant, ultra-thin fiber-reinforced silica aerogel material.

[0041] Tests showed that the aerogel material had a thickness of 0.3 mm and a density of 0.24. .

[0042] Example 3.

[0043] (1) Select a diameter of 5μm and a length of 7mm. Short-cut fibers are placed in a dispersing machine for dispersing. Water is selected as the solvent. Before dispersing, 10% of the fiber mass fraction of PVA adhesive is added to the solvent. The dispersing rate is 300 r / min.

[0044] (2) The dispersed fiber slurry was placed in a Buchner funnel for filtration for 0.7 hours to obtain ultra-thin wet fibers.

[0045] (3) Dry the ultra-thin wet fiber at a temperature of 100°C for 3 hours.

[0046] (4) Place the dried ultrathin fiber layer into a flat mold and add a mixed sol solution until the fiber is completely submerged. The mixed sol solution consists of silica sol and acid. The silica sol solution contains 15% particles with a particle size of 6 nm and a pH of 12. The acid is... The final pH of the mixed solution was controlled at 7.

[0047] (5) After the mold is closed, it is left to stand at room temperature for 30 hours, then placed at 90°C and heated for 60 hours. After cooling, the mold is opened to obtain wet gel.

[0048] (6) Place the wet gel in an ethanol solution with a volume of 22 times its own volume for solvent replacement. The replacement time is 8 days, and the volume of the organic solution during replacement is 20 times the volume of the hydrogel.

[0049] (7) The replaced hydrogel was subjected to supercritical drying using a drying solvent of [missing information]. The drying pressure is 8 MPa, which yields a lightweight, high-temperature resistant, ultra-thin fiber-reinforced silica aerogel material.

[0050] Tests showed that the aerogel material had a thickness of 0.4 mm and a density of 0.22. .

[0051] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention, which is defined by the claims.

Claims

1. A method for preparing a fiber-reinforced silica aerogel material, characterized in that, Includes the following steps: 1) Inorganic fibers are mixed with an adhesive solution and dispersed to obtain fiber slurry; 2) The fiber slurry is placed in a filtration device for vacuum filtration to obtain a wet fiber layer; 3) Dry the wet fiber layer to obtain a dry fiber layer; 4) Place the dry fiber layer in a flat mold and add a silica sol mixture to completely immerse the fiber to obtain a fiber impregnated material; 5) After the flat mold is closed, it is left to stand at room temperature and then heated. After cooling, the mold is opened to obtain wet gel. 6) The wet gel is placed in a solvent for displacement to obtain the displaced gel; 7) The replaced gel is subjected to supercritical drying to obtain fiber-reinforced silica aerogel.

2. The preparation method according to claim 1, characterized in that, In step 1), the inorganic fibers are oxide fibers, and the oxides include quartz, mullite, etc. , One of the following: the inorganic fiber has a diameter of 0.3~8μm and a length of 5~10mm; the adhesive is one or both of polyvinyl alcohol or cellulose, with a mass fraction of 5%~20%; the solvent of the solution is water or ethanol.

3. The preparation method according to claim 1 or 2, characterized in that, The dispersion rate in step 1) is 200~400 r / min.

4. The preparation method according to claim 1, characterized in that, The filtration time in step 2) is 0.5~1h.

5. The preparation method according to claim 1, characterized in that, In step 3), the drying temperature is 80~120℃ and the drying time is 2~4h.

6. The preparation method according to claim 1, characterized in that, Step 4) involves a silica sol mixture comprising silica sol and acid; the silica sol contains 5%–25% particles with a particle size of 3–30 nm; the acid used is HCl. , One of them; the pH of the mixed solution is 6-8.

7. The preparation method according to claim 1, characterized in that, In step 5), let it stand at room temperature for 24-36 hours; then heat it to 80-100℃ and continue for 48-72 hours.

8. The preparation method according to claim 1, characterized in that, In step 6), the wet gel is placed in an ethanol solution for solvent replacement. The volume of the ethanol solution is 20 to 25 times the volume of the wet gel itself, and the volume of the organic solution is 15 to 25 times the volume of the hydrogel. The replacement time is 7 to 10 days.

9. The preparation method according to claim 1, characterized in that, The drying solvent in step 7) is The drying pressure is 5~10MPa.

10. A fiber-reinforced silica aerogel material, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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