A graphene-based composite aerogel with ultra-high tensile elasticity and its preparation method and application

Abstract

The present invention relates to a graphene-based composite aerogel with ultra-high tensile elasticity, a preparation method and application thereof, and relates to the field of graphene, comprising reduced graphene oxide and at least one nanofiber, wherein the weight ratio of reduced graphene oxide to the graphene-based composite aerogel is 5% to 99%, and the maximum reversible tensile strain of the material of the graphene-based composite aerogel itself is 500% to 3000%. The present invention can obtain a graphene-based composite aerogel having ultra-high tensile strain and elastic strain (i.e. ultra-high tensile elasticity) by constructing a highly curled three-dimensional cross-linked network and strengthening the three-dimensional network through a composite strategy.

Description

Technical Field

[0001] The present invention relates to the field of graphene, and in particular to a graphene-based composite aerogel with ultra-high tensile elasticity, and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Since Kistler produced the world's first SiO 2 Aerogel, a three-dimensional nanomaterial with ultra-low density, ultra-high porosity, and ultra-high specific surface area, has rapidly attracted attention and development. With the gradual maturity of aerogel preparation methods such as solvent replacement, supercritical drying, and sol-gel methods, as well as the development of inorganic matrix, organic polymer matrix, cellulose-based, and carbon-based aerogels, the development trend of aerogels has become more functional and green, and at the same time, aerogels have been fully developed in the fields of mechanics, thermodynamics, optics, electromagnetism, and electrochemistry. However, the brittle and fragile properties of aerogels make it impossible for them to have super tensile properties like polymer materials such as rubber, and this feature also greatly limits the functional application of aerogels.

[0004] In 2009, the first graphene aerogel macroscopic material came into being. At present, it can be observed that the reversible compressive strain of graphene aerogel is as high as 99%, and the compressive strength decay is less than 5% after 1 million fatigue tests. In comparison, the compressive elasticity of graphene aerogel is far superior to its tensile performance. In the Chinese invention patent with application number CN108314000A, the author obtained a stretchable all-carbon aerogel with a maximum tensile strain of 200% by designing a microscopic buckling structure. The aerogel has good application prospects in the field of logic sensors. However, due to the lack of an ideal structural model and an effective preparation method, the elastic strain of this type of material is far behind that of polymer elastomers. There has always been a gap in graphene-based aerogels that have both ultra-high tensile strain (i.e., ultra-high tensile strain > 400%) and elastic strain, and its preparation method is an unresolved technical problem in this field. Summary of the invention

[0005] Purpose of the Invention

[0006] The purpose of the present invention is to provide a graphene-based composite aerogel with ultra-high tensile elasticity, and a preparation method and application thereof. By constructing a highly curled three-dimensional cross-linked network and strengthening the three-dimensional network with a composite strategy, a graphene-based composite aerogel with ultra-high tensile strain and elastic strain (i.e., ultra-high tensile elasticity) can be obtained.

[0007] Solution

[0008] To achieve the purpose of the present invention, an embodiment of the present invention provides a graphene-based composite aerogel with ultra-high tensile elasticity, which includes reduced graphene oxide and at least one nanofiber, wherein the weight ratio of reduced graphene oxide to the graphene-based composite aerogel is 5% to 99%, and optionally, the maximum reversible stretching of the material itself of the graphene-based composite aerogel is 500% to 3000%.

[0009] In the present invention, the maximum reversible tensile strain of the material itself refers to the fact that it does not rely on the macroscopic structure (for example, the material is made into a serpentine structure or a spiral structure, which is dependent on the macroscopic structure - the tensile strain is increased by changing the shape of the material). The graphene-based composite aerogel of the present invention does not need to change the shape of the material, and relies on the characteristics of the material itself to make the tensile strain of the material reach 500% to 3000%.

[0010] Generally, water and additives (such as ascorbic acid and sodium dodecylbenzene sulfonate) are added during the preparation of graphene-based composite aerogels. The additives and water are usually removed during the preparation of aerogels, so the composite material generally contains only reduced graphene oxide and nanofibers.

[0011] Furthermore, the mass ratio of graphene oxide to total solids is 10% to 99%, optionally 33% to 99%.

[0012] Furthermore, the nanofiber is selected from one or more of aramid nanofiber, cellulose nanofiber, chitin nanofiber, carbon nanotube, carbon nanofiber, ceramic nanofiber, chitosan nanofiber, and polyvinyl alcohol nanofiber.

[0013] Optionally, the maximum reversible tensile strain of the graphene-based composite aerogel material itself is 800%-3000%;

[0014] And / or, the graphene-based composite aerogel has a highly curled three-dimensional cross-linked network.

[0015] On the other hand, a method for preparing a graphene-based composite aerogel with ultra-high tensile elasticity is provided, comprising the following steps:

[0016] 1) constructing a macroporous structure of an aqueous dispersion containing graphene oxide and nanofibers by a template method, and further reducing the aqueous dispersion to obtain a reduced graphene oxide / nanofiber composite hydrogel;

[0017] The solid content of the mixed dispersion is 0.1% to 3%, and the weight ratio of graphene oxide to the total solid is 5% to 99%;

[0018] 2) drying the reduced graphene oxide / nanofiber composite hydrogel of step 1) to obtain a reduced graphene oxide / nanofiber composite aerogel;

[0019] 3) The reduced graphene oxide / nanofiber composite aerogel of step 2) is subjected to a compression-annealing treatment to highly curl the internal structure of the aerogel, thereby obtaining a reduced graphene oxide-based composite aerogel with high tensile elasticity.

[0020] The present invention is realized by the following technical route, and the main steps are: (1) mixing a graphene oxide dispersion liquid and a nanofiber dispersion liquid, constructing a macroporous structure by a template method, and further reducing to obtain a reduced graphene oxide / nanofiber composite hydrogel; (2) drying the reduced graphene oxide / nanofiber composite hydrogel obtained in step (1) to obtain a reduced graphene oxide / nanofiber composite aerogel; (3) subjecting the three-dimensional network of the composite aerogel obtained in step (2) to a highly curled internal structure (microstructure) by a compression-annealing method to obtain a graphene-based composite aerogel with ultra-high tensile elasticity.

[0021] Furthermore, the size of the macroporous structure described in step (1) is greater than 50 microns in any dimension and is included in this range.

[0022] The present invention includes a two-step molding process: first, a one-step molding process is used to prepare a reduced graphene oxide composite aerogel with a macroporous structure. The purpose of the macroporous structure is that after high compression, the entanglement of the three-dimensional network is less, and the curled network can be stretched and opened. The purpose of compounding other components is to improve the strength of the three-dimensional network so that the three-dimensional network of the material will not break at a high stretch ratio; secondary molding, the macroporous network of the above-mentioned composite aerogel is highly curled by compression annealing to prepare a graphene-based composite aerogel with ultra-high tensile elasticity, wherein the degree of curling of the three-dimensional network structure determines the stretching ratio of the material, and the key technology is to control the pre-compression ratio of the aerogel during compression heat treatment within the range of 85% to 99%. The maximum reversible tensile strain of the prepared graphene-based composite aerogel is 500% to 3000%, and the above elasticity can be maintained within the range of -196°C to 300°C. In addition, the material has a low material density, good electrical conductivity and photothermal conversion capability. The overall invention process is simple, safe and environmentally friendly, easy to industrially produce, and meets the needs of the functional development trend of aerogels.

[0023] Furthermore, in the mixed dispersion of step 1), the weight ratio of graphene oxide to total solids is 10% to 99%, optionally 33% to 99%.

[0024] Furthermore, the solid content of the mixed dispersion in step 1) is 0.5% to 3%, optionally 0.5% to 2%.

[0025] Furthermore, in step 1), the nanofibers include one or more of aramid nanofibers, cellulose nanofibers, chitin nanofibers, carbon nanotubes, carbon nanofibers, ceramic nanofibers, chitosan nanofibers, and polyvinyl alcohol nanofibers.

[0026] Furthermore, in step 1), the reduction method includes one or more of chemical reduction, heating reduction, and microwave reduction.

[0027] Furthermore, in step 1), the reduction method is: reacting at 70-95° C. for 3-20 h, optionally at 80-90° C. for 5-12 h, optionally at 80° C. for 10 h.

[0028] Furthermore, in step 1), in the template method, the template used is selected from one or more of a bubble template, an emulsion template, and an ice template.

[0029] Optionally, in step 1), the reaction system of the mixed dispersion further comprises a reducing agent, and the weight ratio of the reducing agent to the mixed dispersion is 0.1-5%, optionally 0.3-3%; optionally, the reducing agent is ascorbic acid.

[0030] Furthermore, in step 1), a bubble template method is used, and the mixed dispersion is foamed to 1.5 to 2.5 times and then subjected to a reduction reaction in the template; optionally, the reaction system of the mixed dispersion also includes a surfactant, and optionally, the weight ratio of the surfactant to the mixed dispersion is 0.1 to 5%, optionally 0.1 to 1%; optionally, the surfactant is sodium dodecylbenzene sulfonate.

[0031] As an alternative, in step 1), in step 1), an emulsion template method is adopted, and the mixed dispersion is formed into an emulsion by adding an oily emulsion and then a reduction reaction is carried out in the template; optionally, the oily emulsion is cyclohexane.

[0032] Furthermore, in step 2), the drying method is one or more of freeze drying, supercritical drying, and freezing and thawing followed by normal pressure drying.

[0033] Furthermore, in the freeze-thaw and then normal pressure drying method, the freeze-thaw times are at least once, the normal pressure drying temperature is 10-75°C, optionally the normal pressure drying temperature is 15-65°C, optionally the normal pressure drying temperature is 20-60°C. Generally, direct normal pressure drying will reduce the volume of aerogel, and freezing and thawing followed by normal pressure drying will result in a smaller change in the composite gel before and after drying. Freeze drying and supercritical drying will generally result in a smaller change in the composite gel before and after drying. If the volume is reduced too significantly during the drying process, it will affect the performance of the composite gel.

[0034] Furthermore, in step 3), the compression adopts uniaxial compression, biaxial compression and / or three-dimensional compression.

[0035] Further, and / or, in step 3), during the compression-annealing treatment, the compression ratio is controlled to be 85% to 99%, optionally 85% to 97%, optionally 90% to 97%.

[0036] And / or, in step 3), the annealing temperature during the compression-annealing treatment is 180-3000°C, optionally 200-800°C; optionally 300-500°C.

[0037] Preferably, in step 3), during the compression-annealing treatment, the compression ratio is controlled to be 90% to 97% and the annealing temperature is controlled to be 300 to 500°C.

[0038] And / or, in step 3), the compression-annealing method is: compressing the composite aerogel to a specified ratio, using a clamp to fix the shape and then annealing.

[0039] Furthermore, the method for oxidizing graphene is as follows: in an ice-water bath environment, concentrated sulfuric acid is added to a container, and flake graphite powder and potassium permanganate are slowly added in sequence under stirring, and concentrated sulfuric acid is continued to be added. After reacting for 1 to 3 hours, the temperature of the water bath is adjusted to 45 to 55° C., and after reacting for 5 to 9 hours, the mixed slurry is evenly and slowly poured into 3L of ice water under stirring, and finally hydrogen peroxide is added until the solution turns orange or khaki, the solution is allowed to settle, the precipitate is washed to neutrality, water is added for mechanical stirring and dispersion, and unpeeled graphite oxide is removed by centrifugation to obtain an aqueous dispersion of graphene oxide; optionally, the weight ratio of flake graphite powder and potassium permanganate is 1:3 to 5, and optionally the weight ratio is 1:4; optionally, the fineness of the flake graphite powder is 150 to 200 mesh.

[0040] On the other hand, there is provided an application of the graphene-based composite aerogel or the graphene-based composite aerogel prepared by the preparation method in the fields of stretchable conductors, smart sensors or aerospace.

[0041] Beneficial Effects

[0042] The ultra-high stretchable graphene-based composite aerogel prepared by the present invention has an ultra-wide maximum reversible tensile strain comparable to that of elastic materials such as rubber: 500%-3000%; the material is light and structurally stable, and can undergo complex deformations such as stretching, compression, bending, and torsion. The graphene-based composite aerogel prepared by the present invention has relatively stable electromechanical response characteristics within the tensile strain range of 50%-3000%. The graphene-based composite aerogel prepared by the present invention still has the above properties in liquid nitrogen (-196°C).

[0043] The ultra-stretched graphene-based composite prepared by the present invention has great application prospects in the fields of stretchable conductors, smart sensors and aerospace. The preparation process of the present invention is simple, the manufacturing cost is low, it is green and environmentally friendly, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] One or more embodiments are exemplarily described by the pictures in the accompanying drawings, and these exemplary descriptions do not constitute limitations on the embodiments. The special word "exemplary" here means "used as an example, embodiment or illustrative". Any embodiment described as "exemplary" here is not necessarily interpreted as being superior or better than other embodiments.

[0045] Figure 1 Schematic diagram of the stretching process of the ultra-high tensile elastic graphene-based composite aerogel prepared by the present invention;

[0046] Figure 2 It is the tensile stress-strain curve of the ultra-high tensile elastic graphene-based composite aerogel prepared by the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise expressly stated, throughout the specification and claims, the term "including" or its variations such as "comprising" or "including" will be understood to include the stated elements or components, without excluding other elements or other components.

[0048] In addition, in order to better illustrate the present invention, numerous specific details are provided in the specific embodiments below. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some embodiments, raw materials, components, methods, means, etc. well known to those skilled in the art are not described in detail to highlight the main purpose of the present invention. Percentages in all formulations of the present invention are weight ratios.

[0049] The graphene oxide in the following examples was prepared as follows:

[0050] The modified Hummers oxidation method is used to prepare the required graphene oxide aqueous dispersion. 10g of 180 mesh flake graphite, 40g of potassium permanganate powder and 600mL of 98% concentrated sulfuric acid solution are placed in a -18°C refrigerator for more than 8 hours. Add 400mL of concentrated sulfuric acid to a beaker under an ice-water bath environment, slowly add graphite powder and potassium permanganate in sequence under stirring, and finally add the remaining concentrated sulfuric acid. The above operation process is kept at a low temperature and no water can be mixed in. After reacting for 2h, adjust the temperature of the water bath to 50°C. After reacting for 7h, pour the mixed slurry evenly and slowly into 3L of ice water under stirring. Finally, add hydrogen peroxide and wait until the solution turns orange or khaki. The solution is allowed to settle. Wash the prepared precipitate until it is neutral, add water for mechanical stirring and dispersion, and centrifuge to remove the unexfoliated graphite oxide to obtain a graphene oxide aqueous dispersion.

[0051] In the following embodiments, the tensile strain is tested by using a conventional universal material testing machine in a normal tensile mode, with a tensile rate of 50 mm / min until the material breaks.

[0052] In the following embodiments, the rotation speed of the high-speed magnetic stirring is in the range of 1500 to 3000 rpm, and may exceed this range depending on the actual situation (adjusted according to the foaming situation or the emulsion situation).

[0053] In the following embodiments, the uniaxial compression-annealing method is explained as compressing the prepared aerogel material in a certain direction using a clamp to a certain ratio (for example, a compression ratio of 90% means that the volume after compression is 10% of the volume before compression), and then fixing the clamp and annealing the sample and the clamp together.

[0054] In the following examples, all raw materials are commercially available, among which the chemicals are of analytical grade, and the average diameter of the nanofibers is less than 200 nanometers, and the average length is not less than 1 micrometer.

[0055] Example 1

[0056] (1) 30 mL of 10 mg / mL graphene oxide aqueous dispersion and 30 mL of 10 mg / mL cellulose nanofiber aqueous dispersion were mixed evenly in a beaker, and the reduced graphene oxide / cellulose nanofiber composite hydrogel was prepared by chemical reduction and bubble template method to obtain a macroporous structure. Specifically, 0.6 g of ascorbic acid and 2 mL of 50 mg / mL sodium dodecylbenzene sulfonate aqueous solution were added to the above mixed solution, and then high-speed magnetic stirring was applied to foam the mixed solution to about 2 times, and the foamed solution was divided into small glass bottles and transferred to an 80°C oven for reaction for 10 hours to prepare the reduced graphene oxide / cellulose nanofiber composite hydrogel.

[0057] (2) Drying the reduced graphene oxide / cellulose nanofiber composite hydrogel prepared in step (1) by a normal pressure drying method to obtain a reduced graphene oxide / cellulose nanofiber composite aerogel. Specifically, the composite hydrogel sample is completely frozen in an ordinary refrigerator (-18°C), then taken out and completely thawed, and finally thoroughly dried in a 60°C oven or at room temperature to obtain a reduced graphene oxide / cellulose nanofiber composite aerogel.

[0058] (3) The obtained reduced graphene oxide / cellulose nanofiber composite aerogel is subjected to a uniaxial compression-annealing method to highly curl the internal structure, and the compression ratio is controlled to 90% and the annealing temperature is controlled to 300°C, thereby obtaining a graphene / cellulose nanofiber composite aerogel with ultra-high tensile elasticity.

[0059] The tensile strain effect of the composite aerogel prepared in this example is shown in Figure 1 and Figure 2 The results show that the maximum reversible tensile strain of the prepared composite aerogel can reach more than 800%.

[0060] Example 2

[0061] The preparation process is the same as that of Example 1, except that 99 mL of 10 mg / mL graphene oxide aqueous dispersion, 1 mL of 10 mg / mL cellulose nanofiber aqueous dispersion, 1.98 g of ascorbic acid and 4 mL of 50 mg / mL sodium dodecylbenzene sulfonate aqueous solution are added in step (1). The composite aerogel prepared in this example has a tensile strain of more than 800%.

[0062] Example 3

[0063] The preparation process is the same as that of Example 1, except that 10 mL of 10 mg / mL graphene oxide aqueous dispersion, 90 mL of 10 mg / mL cellulose nanofiber aqueous dispersion, 0.2 g of ascorbic acid and 4 mL of 50 mg / mL sodium dodecylbenzene sulfonate aqueous solution are added in step (1). The composite aerogel prepared in this example has a tensile strain of more than 500%.

[0064] Example 4

[0065] The preparation process is the same as that of Example 1, except that the cellulose nanofibers are replaced with aramid nanofibers to obtain a graphene / aramid nanofiber composite aerogel with ultra-high tensile elasticity. The maximum reversible tensile strain of the composite aerogel prepared in this example can reach more than 800%.

[0066] Example 5

[0067] The preparation process is the same as that of Example 1, except that 10 mL of cellulose nanofibers are replaced with 10 mL of 10 mg / mL carbon nanotube aqueous dispersion and 20 mL of 10 mg / ml aramid nanofiber aqueous dispersion, thereby obtaining a graphene / carbon nanotube / aramid nanofiber composite aerogel with ultra-high tensile elasticity, whose maximum reversible tensile strain can reach more than 800%.

[0068] Example 6

[0069] The preparation process is the same as that of Example 1, except that in step (2), the normal pressure drying method is replaced by a freeze drying method, so that the graphene / cellulose nanofiber composite aerogel with ultra-high tensile elasticity can be obtained. Specifically, the reduced oxide graphene / cellulose nanofiber composite hydrogel prepared in step (1) is freeze dried to obtain the graphene / cellulose nanofiber composite aerogel. The composite aerogel prepared in this example has a maximum reversible tensile strain of more than 800%.

[0070] Example 7

[0071] The preparation process is the same as that of Example 1, except that the compression ratio in step (3) is controlled at 95%, thereby obtaining a graphene / cellulose nanofiber composite aerogel with ultra-high tensile elasticity and a tensile strain of 1000%-1600%, and the maximum reversible tensile strain can reach more than 1500%.

[0072] Example 8

[0073] The preparation process is the same as that of Example 1, except that the bubble template method is replaced by the emulsion template method in step (1), specifically: 60 mL of cyclohexane is added to the mixed solution instead of sodium dodecylbenzene sulfonate, and then mechanically stirred vigorously to form a mixed emulsion, and step (2) is the same as that of Example 5, using a freeze-drying method to prepare a graphene / cellulose nanofiber composite aerogel. The composite aerogel prepared in this example has a tensile strain of more than 800%.

[0074] Example 9

[0075] The preparation process is the same as that of Example 1, except that the compression ratio in step (3) is controlled at 95%. The tensile strain of the composite aerogel prepared in this example can reach 1800%.

[0076] Example 10

[0077] The preparation process is the same as that of Example 1, except that the compression ratio in step (3) is controlled at 97%. The tensile strain of the composite aerogel prepared in this example can reach 3000%.

[0078] Embodiment 11

[0079] The preparation process is the same as that of Example 1, except that the uniaxial compression in step (3) is changed to biaxial compression, and the biaxial compression ratios are controlled at 90% and 50% respectively. The tensile strain of the composite aerogel prepared in this example can reach more than 800%.

[0080] Example 12

[0081] The preparation process is the same as that of Example 1, except that the annealing temperature in step (3) is set to 500° C. The tensile strain of the composite aerogel prepared in this example can reach more than 600%.

[0082] Comparative Example 1

[0083] The preparation process is the same as that in Example 1, except that the bubble template method is not used in step (1), and the mixed dispersion is directly chemically reduced (without foaming) to obtain a reduced graphene oxide / cellulose composite hydrogel, which is then freeze-dried to obtain a reduced graphene oxide / cellulose composite aerogel with a small pore structure, and its maximum reversible tensile strain is less than 50%.

[0084] Comparative Example 2

[0085] The preparation process is the same as that of Example 1, except that the compression ratio in step (3) is controlled at 50%, and the maximum reversible tensile strain of the prepared graphene / cellulose nanofiber composite aerogel is less than 100%.

[0086] Comparative Example 3

[0087] The preparation process is the same as that of Example 1, except that cellulose nanofibers are not added, and the maximum reversible tensile strain of the prepared pure graphene aerogel is 130%.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A graphene-based composite aerogel with ultra-high tensile elasticity, characterized in that: It comprises reduced graphene oxide and at least one nanofiber, wherein: The weight ratio of reduced graphene oxide to the graphene-based composite aerogel is 5% to 99%, and the maximum reversible tensile strain of the graphene-based composite aerogel material itself is 500% to 3000%; The graphene-based composite aerogel is obtained by the following method: (1) mixing a graphene oxide aqueous dispersion with a nanofiber aqueous dispersion, constructing a macroporous structure by a template method, and reducing to obtain a reduced graphene oxide / nanofiber composite hydrogel; the size of the macroporous structure is greater than 50 microns in any dimension; (2) drying the reduced graphene oxide / nanofiber composite hydrogel obtained in step (1) to obtain a reduced graphene oxide / nanofiber composite aerogel; (3) The three-dimensional network of the composite aerogel obtained in step (2) is subjected to a compression-annealing method to highly curl the internal structure to obtain a graphene-based composite aerogel with ultra-high tensile elasticity; the compression adopts uniaxial compression, biaxial compression and / or three-dimensional compression; the compression ratio is controlled to be 85% to 99% during the compression-annealing treatment; and the annealing temperature during the compression-annealing treatment is 180 to 3000°C.

2. The graphene-based composite aerogel according to claim 1, characterized in that: The weight ratio of graphene oxide to total solid is 10% to 99%.

3. The graphene-based composite aerogel according to claim 1, characterized in that: The weight ratio of graphene oxide to total solids is 33% to 99%.

4. The graphene-based composite aerogel according to any one of claims 1 to 3, characterized in that: The nanofiber is selected from one or more of aramid nanofiber, cellulose nanofiber, chitin nanofiber, carbon nanotube, carbon nanofiber, ceramic nanofiber, chitosan nanofiber and polyvinyl alcohol nanofiber.

5. The graphene-based composite aerogel according to any one of claims 1 to 3, characterized in that: The maximum reversible tensile strain of the graphene-based composite aerogel material itself is 800%-3000%.

6. The graphene-based composite aerogel according to any one of claims 1 to 3, characterized in that: It has a highly coiled three-dimensional cross-linked network.

7. A method for preparing a graphene-based composite aerogel with ultra-high tensile elasticity, characterized in that: The steps include: 1) constructing a macroporous structure of an aqueous dispersion containing graphene oxide and nanofibers by a template method, and further reducing the aqueous dispersion to obtain a reduced graphene oxide / nanofiber composite hydrogel; The solid content of the mixed dispersion is 0.1% to 3%, the weight ratio of graphene oxide to the total solid is 5% to 99%; the size of the macroporous structure is greater than 50 microns in any dimension; 2) drying the reduced graphene oxide / nanofiber composite hydrogel of step 1) to obtain a reduced graphene oxide / nanofiber composite aerogel; 3) The reduced graphene oxide / nanofiber composite aerogel of step 2) is subjected to a compression-annealing treatment to highly curl the internal structure of the aerogel to obtain a reduced graphene oxide-based composite aerogel with high tensile elasticity; the compression adopts uniaxial compression, biaxial compression and / or three-dimensional compression; the compression ratio is controlled to be 85% to 99% during the compression-annealing treatment; the annealing temperature during the compression-annealing treatment is 180 to 3000° C.; The maximum reversible tensile strain of the graphene-based composite aerogel material itself is 500% to 3000%.

8. The preparation method according to claim 7, characterized in that: In the mixed dispersion of step 1), the weight ratio of graphene oxide to total solids is 10% to 99%.

9. The preparation method according to claim 7, characterized in that: In the mixed dispersion of step 1), the weight ratio of graphene oxide to total solids is 33% to 99%.

10. The preparation method according to claim 7, characterized in that: The solid content of the mixed dispersion in step 1) is 0.5% to 3%.

11. The preparation method according to claim 7, characterized in that: The solid content of the mixed dispersion in step 1) is 0.5% to 2%.

12. The preparation method according to claim 7, characterized in that: In step 1), the nanofibers include one or more of aramid nanofibers, cellulose nanofibers, chitin nanofibers, carbon nanotubes, carbon nanofibers, ceramic nanofibers, chitosan nanofibers, and polyvinyl alcohol nanofibers.

13. The preparation method according to claim 7, characterized in that: In step 1), the reduction method includes one or more of chemical reduction, heating reduction, and microwave reduction.

14. The preparation method according to any one of claims 7 to 13, characterized in that: In step 1), in the template method, the template used is selected from one or more of a bubble template, an emulsion template, and an ice template.

15. The preparation method according to any one of claims 7 to 13, characterized in that: In step 1), the reaction system of the mixed dispersion further comprises a reducing agent, and the weight ratio of the reducing agent to the mixed dispersion is 0.1-5%.

16. The preparation method according to claim 15, characterized in that: The weight ratio of the reducing agent to the mixed dispersion is 0.3-3%.

17. The preparation method according to claim 15, characterized in that: The reducing agent is ascorbic acid.

18. The preparation method according to claim 14, characterized in that: In step 1), the bubble template method is adopted, and the mixed dispersion is foamed to 1.5 to 2.5 times and then subjected to reduction reaction in the template.

19. The preparation method according to claim 15, characterized in that: The reaction system of the mixed dispersion also includes a surfactant.

20. The preparation method according to claim 19, characterized in that: The weight ratio of the surfactant to the mixed dispersion is 0.1-5%.

21. The preparation method according to claim 19, characterized in that: The weight ratio of the surfactant to the mixed dispersion is 0.1-1%.

22. The preparation method according to claim 19, characterized in that: The surfactant is sodium dodecylbenzene sulfonate.

23. The preparation method according to claim 14, characterized in that: In step 1), an emulsion template method is used, and the mixed dispersion is formed into an emulsion by adding an oily emulsion and then a reduction reaction is carried out in the template.

24. The preparation method according to claim 23, characterized in that: The oil emulsion is cyclohexane.

25. The preparation method according to any one of claims 7 to 13, characterized in that: In step 2), the drying method is one or more of freeze drying, supercritical drying, and freezing and thawing followed by normal pressure drying.

26. The preparation method according to claim 25, characterized in that: In the freeze-thaw followed by normal pressure drying method, the freeze-thaw times are at least once, and the normal pressure drying temperature is 10 to 75°C.

27. The preparation method according to claim 25, characterized in that: The temperature for normal pressure drying is 15-65°C.

28. The preparation method according to claim 25, characterized in that: The temperature for normal pressure drying is 20-60°C.

29. The preparation method according to any one of claims 7 to 13, characterized in that: In step 3), the compression ratio is controlled to be 85% to 97% during the compression-annealing treatment.

30. The preparation method according to any one of claims 7 to 13, characterized in that: In step 3), the compression ratio is controlled to be 90% to 97% during the compression-annealing treatment.

31. The preparation method according to any one of claims 7 to 13, characterized in that: In step 3), the annealing temperature during the compression-annealing treatment is 200 to 800°C.

32. The preparation method according to any one of claims 7 to 13, characterized in that: In step 3), the annealing temperature during the compression-annealing treatment is 300 to 500°C.

33. The preparation method according to any one of claims 7 to 13, characterized in that: In step 3), the compression-annealing method is: compressing the composite aerogel to a specified ratio, using a clamp to fix the shape and then annealing.

34. Use of the graphene-based composite aerogel according to any one of claims 1 to 6 or the graphene-based composite aerogel prepared by the preparation method according to any one of claims 7 to 33 in stretchable conductors, smart sensors or aerospace fields.

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