A novel micro-nano synergistic carbon aerogel-based composite material, a preparation method and applications thereof

Abstract

The application belongs to the technical field of materials, and discloses a preparation method of a novel micro-nano synergic carbon aerogel-based composite material, which comprises the following steps: using nanocellulose gel as raw material, mixing with deionized water after ultrasonic treatment, and obtaining nanocellulose uniform dispersion liquid with a required concentration; mixing the dispersion liquid and an oxidized graphite solution, ultrasonic treatment until gelation, water bath heating, placing in a directional freezing mold, shaping, taking out, and freeze-drying for 10-15 hours to obtain nanofiber / oxidized graphite aerogel; and heat preservation of the nanofiber / oxidized graphite aerogel in an inert gas environment at 450-550 DEG C for 4-4.5 hours, and heat preservation at 950-1050 DEG C for 2-3 hours to obtain the product. The carbon aerogel prepared by the method has excellent high-temperature resistance and oxidation resistance, and has excellent compression resilience, so that it has a wide application prospect in the fields of aerospace and civil high-performance damping, sensors and the like.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, and in particular to a novel micro-nano synergistic carbon aerogel-based composite material, its preparation method, and its application. Background Technology

[0002] Carbon aerogels are three-dimensional network structures composed of interconnected carbon particles. They are a promising new form of carbon with many physicochemical properties, including good porosity, large specific surface area and excellent electrical conductivity, making them promising for a wide range of applications in thermal and acoustic insulators, catalyst supports, adsorbents and supercapacitor electrodes.

[0003] While the brittleness of carbon aerogels has been largely mitigated, nanofiber carbon aerogels still struggle to fully recover their initial three-dimensional shape under significant deformation. This means they are highly susceptible to irreversible permanent deformation during large deformations, which severely limits their practical applications. Furthermore, these carbon aerogels exhibit poor cyclic compressibility, making them unsuitable for real-world use.

[0004] Therefore, how to handle carbon aerogels under large deformations and how to solve problems such as cyclic compressibility and recoverability are of great significance for the practical application of carbon aerogels.

[0005] A search revealed no patent publications related to this invention's patent application. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide a novel micro-nano synergistic carbon aerogel-based composite material, its preparation method, and its application.

[0007] The technical solution adopted by this invention to solve the technical problem is:

[0008] A novel method for preparing micro / nano synergistic carbon aerogel-based composite materials includes the following steps:

[0009] (1) Using nanocellulose gel as raw material, it is mixed with deionized water and sonicated to obtain a uniform dispersion of nanocellulose of the required concentration. The mass concentration of nanocellulose gel in the dispersion is 0.6 to 1.0 wt%.

[0010] (2) Mix the dispersion and graphite oxide solution, sonicate until gel-like, heat in a water bath, place in a directional freezing mold, shape, freeze dry for 10-15 hours to obtain nanofiber / graphite oxide aerogel.

[0011] The mass ratio of the nanocellulose gel in the dispersion to the graphene oxide in the graphene oxide solution is 3-8:4-8.

[0012] (3) The nanofiber / graphite oxide aerogel was kept at 450-550℃ for 4-4.5h in an inert gas environment, and then kept at 950-1050℃ for 2-3h to obtain a novel micro-nano synergistic carbon aerogel-based composite material.

[0013] Furthermore, in step (1), the nanocellulose gel includes long nanofibers and short nanofibers. The short nanofibers have a diameter of 80-150 nm and a length of 1-5 μm; the long nanofibers have a diameter of 80-150 nm and a length of 5-10 μm.

[0014] Furthermore, in step (1), the ultrasound is performed using a 1000-1300W probe ultrasound device, and the ultrasound time is 50-60s.

[0015] Further, in step (2), the graphite oxide solution is a mixture of graphite oxide and water, and the concentration of graphite oxide in the graphite oxide solution is 6-8 mg / mL;

[0016] Alternatively, the method for preparing graphite oxide in the graphite oxide solution in step (2) includes the following steps:

[0017] Graphite powder and NaNO3 were stirred vigorously with H2SO4 in an ice bath for 2 hours. Then KMnO4 was slowly added while keeping the temperature below 20°C. The temperature of the mixture was then raised to 35°C and maintained for 1 hour. Deionized water was then slowly added. The mixture was then heated to 98°C and maintained for 0.5 hours. Deionized water and H2O2 were added to the mixture. After centrifugation and washing to remove residual impurities, the mixture was dried at 60°C for 48 hours to obtain graphite oxide.

[0018] The ratio of graphite powder:NaNO3:H2SO4:KMnO4:deionized water:deionized water:H2O2 (g:g:mL:g:mL:mL:mL) is 5:2.5:130:20:230:500:5.

[0019] Furthermore, in step (2), the ultrasound is performed at a power of 1000-1300W for 25-35 minutes until a gel-like state is achieved;

[0020] Alternatively, in step (2), the water bath heating is performed at 85–95°C for 50–70 minutes.

[0021] Further, in step (2), directional freezing involves placing the solution into the directional freezing mold of the directional freezing device. The directional freezing device includes a liquid nitrogen container, a conductive copper column, and a directional freezing mold. The liquid nitrogen container is arranged horizontally and can hold liquid nitrogen. The conductive copper column is arranged vertically and is made of copper. The lower part of the conductive copper column extends into the liquid nitrogen container and can contact the liquid nitrogen inside the container. The directional freezing mold is coaxially and detachably connected to the top surface of the conductive copper column. The directional freezing mold includes a bottom plate and a side plate. The side plate is tightly and detachably connected vertically above the bottom outer edge. The bottom plate and the side plate form a hollow interior. The hollow interior of the directional freezing mold can hold the sample to be frozen. The bottom plate of the directional freezing mold is made of copper, and the side plate is made of polytetrafluoroethylene.

[0022] In use, liquid nitrogen is poured to three-quarters of the way down from the top of the container. The sample is placed in the directional freezing mold, which is then placed on top of a copper column. Through the directional cold conduction of the copper column, the sample at the bottom of the directional freezing mold begins to crystallize. Inside the freezing mold, ice crystals perpendicular to the bottom form inside the sample, thus achieving directional freezing.

[0023] Furthermore, in step (3), the inert gas is nitrogen, and the flow rate is 40-50 ml / min.

[0024] Furthermore, in step (3), the heating rate to 450℃~550℃ is 2~4℃ / min, and the heating rate to 950~1050℃ is 4~6℃ / min.

[0025] A novel micro-nano synergistic carbon aerogel-based composite material was prepared by the method described above.

[0026] Applications of the novel micro / nano synergistic carbon aerogel-based composite materials described above in high-performance damping and / or sensors for aerospace and / or civilian applications.

[0027] The beneficial effects achieved by this invention are:

[0028] 1. The method of this invention uses nanocellulose gel as a precursor for carbon aerogel, mixes it with deionized water, and ultrasonically disperses it to obtain a uniform cellulose dispersion. After mixing with graphite oxide solution, the dispersion is first subjected to liquid nitrogen directional freezing, then freeze-dried, and finally carbonized to prepare a three-dimensional macroscopic carbon aerogel. The carbon aerogel prepared by the above method of this invention exhibits excellent high-temperature resistance and oxidation resistance, as well as superior compression resilience, making it promising for applications in aerospace, civilian high-performance damping, and sensors. This method solves the technical problem that existing carbon aerogels cannot meet the practical application requirements due to insufficient cyclic compressibility and recoverability under large deformations.

[0029] 2. The nanofiber / graphite oxide aerogel prepared by the method of the present invention has regularly arranged columnar pores. The addition of graphite oxide not only makes the internal structure of the columnar pores have a large number of nodes, but also greatly increases the proportion of the sheet structure, which will improve its performance to a certain extent and is beneficial to the compression and resilience of carbon aerogel.

[0030] 3. The nanofiber / graphite oxide aerogel prepared by the directional freezing method in this invention controls the crystallization direction of the solution due to the presence of a temperature gradient, resulting in a regular arrangement of the crystallization direction of the cellulose dispersion. This, in turn, causes the cellulose in the solution to align regularly along the crystallization direction of the solution. The temperature gradient directions intersect, and lamellar cellulose grows at this intersection surface. Furthermore, in the direction perpendicular to the intersection of the two temperature gradient directions, the cyclic compressibility and recoverability of the carbon aerogel are improved.

[0031] 4. The carbon aerogel prepared by this invention has greatly improved elasticity. By using nanocellulose to perform liquid nitrogen freezing treatment in a directional freezing device, the compressibility of the carbon aerogel is greatly improved, exhibiting excellent recoverability. When a 40% deformation occurs, it has a rebound rate of more than 85% in the direction perpendicular to the sheet, which greatly improves the cyclic compressibility and recoverability. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structural connection of the directional freezing device in this invention;

[0033] Figure 2 These are SEM images of a novel micro-nano synergistic carbon aerogel-based composite material prepared in Example 1 of this invention at different magnifications.

[0034] Figure 3 These are SEM images of the internal structure of the carbon aerogel composite material obtained in Example 2 of this invention at different magnifications.

[0035] Figure 4 SEM images of the internal structure of the carbon aerogel composite material prepared in Comparative Example 2 of this invention at different magnifications;

[0036] Figure 5 The compression resilience of a novel micro-nano synergistic carbon aerogel-based composite material prepared in Example 1 of the present invention, the carbon aerogel composite material prepared in Comparative Example 2, and the carbon aerogel composite material prepared in Example 2 at 40% deformation. Detailed Implementation

[0037] To better understand the present invention, the present invention will be further described in detail below with reference to the embodiments. However, the scope of protection of the present invention is not limited to the scope represented by the embodiments.

[0038] Unless otherwise specified, all raw materials used in this invention are conventional commercially available products. Unless otherwise specified, all methods used in this invention are conventional methods in the field. All substances used in this invention are of conventional usage quality.

[0039] A novel method for preparing micro / nano synergistic carbon aerogel-based composite materials includes the following steps:

[0040] (1) Using nanocellulose gel as raw material, it is mixed with deionized water and sonicated to obtain a uniform dispersion of nanocellulose of the required concentration. The mass concentration of nanocellulose gel in the dispersion is 0.6 to 1.0 wt%.

[0041] (2) Mix the dispersion and graphite oxide solution, sonicate until gel-like, heat in a water bath, place in a directional freezing mold, shape, freeze dry for 10-15 hours to obtain nanofiber / graphite oxide aerogel.

[0042] The mass ratio of the nanocellulose gel in the dispersion to the graphene oxide in the graphene oxide solution is 3-8:4-8.

[0043] (3) The nanofiber / graphite oxide aerogel was kept at 450-550℃ for 4-4.5h in an inert gas environment, and then kept at 950-1050℃ for 2-3h to obtain a novel micro-nano synergistic carbon aerogel-based composite material.

[0044] Preferably, the nanocellulose gel in step (1) includes long nanofibers and short nanofibers, wherein the short nanofibers have a diameter of 80-150 nm and a length of 1-5 μm; and the long nanofibers have a diameter of 80-150 nm and a length of 5-10 μm.

[0045] Preferably, in step (1), the ultrasound is performed using a 1000-1300W probe ultrasound device, and the ultrasound time is 50-60s.

[0046] Preferably, in step (2), the graphite oxide solution is a mixture of graphite oxide and water, and the concentration of graphite oxide in the graphite oxide solution is 6-8 mg / mL;

[0047] Alternatively, the method for preparing graphite oxide in the graphite oxide solution in step (2) includes the following steps:

[0048] Graphite powder and NaNO3 were stirred vigorously with H2SO4 in an ice bath for 2 hours. Then KMnO4 was slowly added while keeping the temperature below 20°C. The temperature of the mixture was then raised to 35°C and maintained for 1 hour. Deionized water was then slowly added. The mixture was then heated to 98°C and maintained for 0.5 hours. Deionized water and H2O2 were added to the mixture. After centrifugation and washing to remove residual impurities, the mixture was dried at 60°C for 48 hours to obtain graphite oxide.

[0049] The ratio of graphite powder:NaNO3:H2SO4:KMnO4:deionized water:deionized water:H2O2 (g:g:mL:g:mL:mL:mL) is 5:2.5:130:20:230:500:5.

[0050] Preferably, in step (2), the ultrasound is performed at a power of 1000-1300W for 25-35 minutes until a gel-like state is formed.

[0051] Alternatively, in step (2), the water bath heating is performed at 85–95°C for 50–70 minutes.

[0052] Preferably, in step (2), directional freezing involves placing the solution into the directional freezing mold of a directional freezing device. The directional freezing device includes a liquid nitrogen container, a conductive copper column, and a directional freezing mold. The liquid nitrogen container is arranged horizontally and can hold liquid nitrogen. The conductive copper column is arranged vertically and is made of copper. The lower part of the conductive copper column extends into the liquid nitrogen container and can contact the liquid nitrogen inside the container. The directional freezing mold is coaxially and detachably connected to the top surface of the conductive copper column. The directional freezing mold includes a bottom plate and a side plate. The side plate is tightly and detachably connected vertically above the bottom outer edge. The bottom plate and the side plate form a hollow interior. The hollow interior of the directional freezing mold can hold the sample to be frozen. The bottom plate of the directional freezing mold is made of copper, and the side plate is made of polytetrafluoroethylene.

[0053] In use, liquid nitrogen is poured to three-quarters of the way down from the top of the container. The sample is placed in the directional freezing mold, which is then placed on top of a copper column. Through the directional cold conduction of the copper column, the sample at the bottom of the directional freezing mold begins to crystallize. Inside the freezing mold, ice crystals perpendicular to the bottom form inside the sample, thus achieving directional freezing.

[0054] Preferably, the inert gas in step (3) is nitrogen, and the flow rate is 40-50 ml / min.

[0055] Preferably, in step (3), the heating rate to 450℃~550℃ is 2~4℃ / min, and the heating rate to 950~1050℃ is 4~6℃ / min.

[0056] A novel micro-nano synergistic carbon aerogel-based composite material was prepared by the method described above.

[0057] Applications of the novel micro / nano synergistic carbon aerogel-based composite materials described above in high-performance damping and / or sensors for aerospace and / or civilian applications.

[0058] Specifically, the relevant preparation and testing methods are as follows:

[0059] The raw materials in the following examples were sourced from the following locations:

[0060] The cellulose gel was purchased from Zhongshan Nanofiber New Materials Co., Ltd.

[0061] Sodium nitrate (NaNO3, analytical grade), concentrated sulfuric acid (H2SO4, analytical grade), and potassium permanganate (KMnO4, analytical grade) were purchased from Tianjin Damao Reagent Co., Ltd.

[0062] Hydrogen peroxide (H2O2, analytical grade) was purchased from Tianjin Jiangtian Chemical Technology Co., Ltd.

[0063] The graphite powder has a purity of ≥99.95% and is supplied by Shanghai Aladdin Reagent Co., Ltd.

[0064] The following examples illustrate the preparation of graphene oxide (GO) using a modified Hummer method, as detailed below:

[0065] 5g of graphite powder and 2.5g of NaNO3 were vigorously stirred with 130mL of H2SO4 in an ice bath for 2 hours. Then, 20g of KMnO4 was slowly added while maintaining the temperature below 20°C. The mixture was then heated to 35°C and maintained for 1 hour. Next, 230mL of deionized water was slowly added, and the mixture was heated to 98°C for 0.5 hours. 500mL of deionized water and 5mL of H2O2 were added to the mixture. After centrifugation and washing to remove residual impurities, the mixture was dried at 60°C for 48 hours to obtain graphite oxide.

[0066] Example 1

[0067] A novel method for preparing micro / nano synergistic carbon aerogel-based composite material includes the following steps:

[0068] (1) Using nano-long cellulose gel as raw material, mix with deionized water and sonicate at 1200W power for 50s to obtain a uniform dispersion of nano-long cellulose with the required concentration. The mass concentration of nano-long cellulose in the dispersion is 0.9wt%.

[0069] (2) The dispersion and graphite oxide solution are mixed and sonicated at 1000W for 30 minutes until gel-like. After heating in a water bath at 95°C for 70 minutes, the mixture is placed in a directional freezing mold of a directional freezing device. After molding, it is taken out and freeze-dried for 12 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide gel in the dispersion to graphite oxide in the graphite oxide solution is 6:8 by mass, and the concentration of graphite oxide in the graphite oxide solution is 8 mg / mL.

[0070] (3) A novel micro / nano synergistic carbon aerogel-based composite material was obtained by heating the nanofiber / graphite oxide aerogel to 500℃ at a rate of 4℃ / min under nitrogen atmosphere, holding it at that temperature for 4 hours, and then heating it to 1000℃ at a rate of 5℃ / min and holding it at that temperature for 2 hours. Under 40% deformation, the carbon aerogel exhibited significantly improved pressure and resilience in its three-dimensional macroscopic shape, with a resilience exceeding 85%, thus expanding the limitations of practical everyday applications.

[0071] Among them, such as Figure 1 As shown, the directional freezing device includes a liquid nitrogen container 1, a conductive copper column 2, and a directional freezing mold. The liquid nitrogen container is arranged horizontally and can hold liquid nitrogen. The conductive copper column is arranged vertically and is made of copper. The lower part of the conductive copper column extends into the liquid nitrogen container and can contact the liquid nitrogen inside the container. The lower end of the copper column is immersed in the liquid nitrogen, which is stored in a cold source container. The conductive copper column can conduct the temperature of the liquid nitrogen to the directional freezing mold, thereby freezing the sample inside the directional freezing mold. The directional freezing mold is coaxially and detachably connected to the top surface of the conductive copper column. The directional freezing mold includes a bottom plate 3 and a side plate 4. The side plate is tightly and detachably connected vertically above the bottom outer edge. The bottom plate and the side plate form a hollow interior (not labeled in the figure). The hollow interior of the directional freezing mold can hold the sample to be frozen. The bottom plate of the directional freezing mold is made of copper, and the side plate is made of polytetrafluoroethylene.

[0072] When using it, pour liquid nitrogen to three-quarters of the way down from the top of the container, place the sample in the directional freezing mold, and place it on top of the copper column. Through the directional cold conduction of the copper column, the sample at the bottom of the directional freezing mold begins to crystallize, and ice crystals perpendicular to the bottom are formed inside the sample in the freezing mold, thus achieving directional freezing.

[0073] like Figure 2 As shown, the structure of the novel micro-nano synergistic carbon aerogel-based composite material is still a tightly packed columnar pore stack, with the proportion of the regularly packed columnar pore area exceeding 95%, and no macroscopic looseness is observed.

[0074] Example 2

[0075] This embodiment provides a method for preparing a carbon aerogel composite material, which includes the following steps:

[0076] (1) Using nano-long cellulose gel as raw material, mix with deionized water and sonicate at 1100W for 60s to obtain a uniform dispersion of nano-long cellulose of the required concentration. The mass concentration of nano-long cellulose in the dispersion is 0.8wt%.

[0077] (2) The dispersion and graphite oxide solution were mixed and sonicated at 1100W for 30 minutes until gel-like. After heating in a water bath at 90°C for 1 hour, the mixture was placed in a directional freezing mold and then freeze-dried for 14 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide gel in the dispersion to graphite oxide in the graphite oxide solution was 8:6 by mass, and the concentration of graphite oxide in the graphite oxide solution was 6 mg / mL.

[0078] (3) The nanofiber / graphite oxide aerogel was heated to 550°C at a rate of 3°C / min under nitrogen and held for 4.5 h. Then it was heated to 1050°C at a rate of 6°C / min and held for 3 h to obtain a carbon aerogel composite material.

[0079] like Figure 3 As shown, the microstructure of stacked micro-sheets forms a porous structure with an approximately elliptical arrangement. The smoother parts are composed of graphite oxide, while the more curved connecting parts between the sheets are composed of cellulose oxide. Over 95% of the sample consists of a near-spherical porous structure. This porous structure exhibits uniformity in all directions and can be considered isotropic, resulting in similar compressive resilience in all directions.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a carbon aerogel composite material, the method comprising the following steps:

[0082] (1) Using nano-long cellulose gel as raw material, mix with deionized water and sonicate at 1000W power for 60s to obtain a uniform dispersion of nano-long cellulose of the required concentration. The mass concentration of nano-long cellulose in the dispersion is 1wt%.

[0083] (2) The dispersion and graphite oxide solution were mixed and sonicated at 1000W for 35 minutes until gel-like. After heating in a water bath at 85°C for 50 minutes, the mixture was placed in a directional freezing mold and then freeze-dried for 10 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide gel in the dispersion to graphite oxide in the graphite oxide solution was 4:3 by mass, and the concentration of graphite oxide in the graphite oxide solution was 3 mg / mL.

[0084] The nanofiber / graphite oxide aerogel obtained in Comparative Example 1 has a loose structure and cannot be formed into a bulk structure.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing a carbon aerogel composite material, the method comprising the following steps:

[0087] (1) Using nano-short cellulose gel as raw material, mix with deionized water and sonicate at 1200W for 50s to obtain a uniform dispersion of nano-short cellulose of the required concentration. The mass concentration of nano-short cellulose in the dispersion is 0.8wt%.

[0088] (2) The dispersion and graphite oxide solution are mixed and sonicated at 1000W for 30 minutes until gel-like. After heating in a water bath at 90℃ for 1 hour, the mixture is placed in a directional freezing mold and then freeze-dried for 12 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide gel in the dispersion to graphite oxide in the graphite oxide solution is 6:8 by mass, and the concentration of graphite oxide in the graphite oxide solution is 8 mg / mL.

[0089] (3) The nanofiber / graphite oxide aerogel was heated to 500°C at a rate of 4°C / min under nitrogen and kept at that temperature for 4 hours. Then it was heated to 1000°C at a rate of 5°C / min and kept at that temperature for 2 hours to obtain a carbon aerogel composite material.

[0090] like Figure 4 As shown, the connection between short fibers and graphite oxide is not strong and is more easily damaged during carbonization; while in Example 1, the connection between long fibers and graphite oxide is stronger, the structure of the sample is more robust, and the degree of damage after carbonization is less.

[0091] Depend on Figure 5 It can be seen that the pressure and resilience in Comparative Example 2 are not very satisfactory. However, the pressure and resilience of Example 1, which incorporates nano-long cellulose gel, are significantly improved, and its resilience reaches more than 85%.

[0092] Comparative Example 3

[0093] This embodiment provides a method for preparing a carbon aerogel composite material, which includes the following steps:

[0094] (1) Using nano-long cellulose gel as raw material, mix with deionized water and sonicate at 1000W power for 60s to obtain a uniform dispersion of nano-long cellulose of the required concentration. The mass concentration of nano-long cellulose in the dispersion is 1wt%.

[0095] (2) The dispersion and graphite oxide solution are mixed and sonicated at 1000W for 35 minutes until gel-like. After heating in a water bath at 85°C for 50 minutes, the mixture is placed in a directional freezing mold and then freeze-dried for 10 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide aerogel in the dispersion to graphite oxide in the graphite oxide solution is 3:4 by mass, and the concentration of graphite oxide in the graphite oxide solution is 4 mg / mL.

[0096] The nanofiber / graphite oxide aerogel obtained in Comparative Example 3 has a loose structure and cannot be formed into a bulk structure.

[0097] By comparing Examples 1, 2, and Comparative Examples 1 to 3, it can be seen that the preparation method of the present invention has a synergistic effect between the nano-long cellulose gel and the two steps of heating at 450-550℃ for 4-4.5h in an inert gas environment and then heating at 950-1050℃ for 2-3h, which can synergistically improve the relevant properties of the prepared micro-nano synergistic carbon aerogel-based composite material.

[0098] Depend on Figure 5 It can be seen that, compared with the directional method, the nanofiber / graphite oxide aerogel samples prepared by carbonization under 40% deformation showed that Comparative Example 2 and Example 2 experienced lower pressure after carbonization, which is due to the decrease in strength of cellulose after carbonization. Increasing the graphite oxide concentration significantly improved both pressure and resilience, with the resilience reaching over 85%, which is related to the uniqueness of its internal microstructure and the tight connection of the long fibers.

[0099] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for preparing a novel micro / nano synergistic carbon aerogel-based composite material, characterized in that: Its preparation method includes the following steps: (1) Using nano-long cellulose gel as raw material, mix with deionized water and sonicate at 1200W for 50s to obtain a uniform dispersion of nano-long cellulose of the required concentration. The mass concentration of nano-long cellulose in the dispersion is 0.9wt%. The diameter of the nano-long fibers in the nano-long cellulose gel is 80~150nm and the length is 5~10μm. (2) The dispersion and graphite oxide solution are mixed and sonicated at 1000W for 30 minutes until gel-like. After heating in a water bath at 95°C for 70 minutes, the mixture is placed in a directional freezing mold of a directional freezing device. After molding, it is taken out and freeze-dried for 12 hours to obtain nanofiber / graphite oxide aerogel. The ratio of nanofiber / graphite oxide gel in the dispersion to graphite oxide in the graphite oxide solution is 6:8 by mass, and the concentration of graphite oxide in the graphite oxide solution is 8 mg / mL. (3) The nanofiber / graphite oxide aerogel was heated to 500℃ at a rate of 4℃ / min under nitrogen and kept at that temperature for 4h. Then it was heated to 1000℃ at a rate of 5℃ / min and kept at that temperature for 2h to obtain a novel micro-nano synergistic carbon aerogel-based composite material. Under 40% deformation, the carbon aerogel pressure and resilience of its three-dimensional macroscopic shape were significantly improved, and its resilience also reached more than 85%.

2. The novel micro-nano synergistic carbon aerogel-based composite material prepared by the preparation method described in claim 1.

3. The application of the novel micro-nano synergistic carbon aerogel-based composite material as described in claim 2 in aerospace and / or civilian high-performance damping and / or sensors.

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