High-elongation graphene fiber and method of making same

Abstract

The application provides a high-elongation graphene fiber and a preparation method thereof, and the preparation method comprises the following steps: mixing a graphene dispersion liquid and polyvinyl alcohol to obtain a spinning solution; the graphene dispersion liquid comprises graphene and a compounded dispersant, and the compounded dispersant is composed of an amphoteric ionic dispersant and a non-ionic dispersant; solution spinning is performed on the spinning solution to obtain a graphene nascent fiber; and the graphene nascent fiber is reduced and then carbonized to obtain the high-elongation graphene fiber. The application solves the problem of stable and uniform dispersion of the graphene liquid phase by developing the compounded dispersant, and the problem of insufficient high elongation of the graphene fiber is solved by using a molecular mediation mode, so that the finally-prepared graphene fiber not only has excellent elongation performance, but also has uniform morphology, a smooth surface and certain strength, and the preparation process is simple, short in time consumption and low in energy consumption.

Description

Technical Field

[0001] This invention relates to the field of graphene fiber technology, and in particular to a high-elongation graphene fiber and its preparation method. Background Technology

[0002] As a key application of two-dimensional graphene materials, the development of its preparation technology has always attracted much attention. Since the successful preparation of graphene oxide liquid crystals for the first time in 2011, the field has generally followed the preparation route of "solution spinning-drying and stretching-chemical reduction" using graphene oxide as a precursor. This technical path is defined by the academic community as the classic preparation method for reduced graphene oxide fibers. However, intrinsic graphene has inherent characteristics such as low chemical activity and significant surface hydrophobicity. In addition, the strong van der Waals forces between the layers make it prone to aggregation and difficult to disperse uniformly, which greatly limits its direct application in fiber preparation. In contrast, graphene oxide, due to the rich oxygen-containing functional groups on the carbon skeleton surface, endows it with excellent dispersion stability in most polar solvents, which can effectively support the direct construction of one-dimensional fibrous structures through solution spinning. However, it should be noted that the inevitable destruction of the carbon network structure during the reduction process, such as the formation of structural defects such as vacancies and topological defects, results in a significant gap between the key properties of the final graphene fibers and those of intrinsic graphene. Therefore, breaking through the direct preparation technology using intrinsic graphene as raw material has become one of the core strategies to solve the current performance bottleneck of graphene fibers and achieve efficient inheritance of their intrinsic properties.

[0003] Graphene fibers, with their high conductivity and flexible weavable properties, have demonstrated outstanding performance in the field of flexible electronics. For example, they can be integrated into flexible displays and wearable sensors to achieve real-time monitoring of human physiological parameters. Therefore, the elongation of graphene fibers is one of the core indicators for achieving high-performance applications. High elongation allows the fibers to conform to the curves of the human body, reducing friction during movement; furthermore, fibers with good elongation can induce the orientation of graphene sheets through stretching, forming a continuous conductive network. The elongation of graphene fibers is not only a core manifestation of their mechanical properties but also a key factor determining their functional characteristics and industrialization feasibility. Future efforts require breakthroughs in existing performance bottlenecks through material design, process optimization, and interdisciplinary collaborative innovation to promote their large-scale application in fields such as smart materials and high-end manufacturing.

[0004] Polymer materials play a crucial role in modern materials science and industry, providing an indispensable functional material foundation for cutting-edge fields such as electronics, information, biomedicine, and new energy. Drawing inspiration from the preparation of chemical fibers, polymers such as polyvinyl alcohol, polyethylene, polyacrylonitrile, polyimide, polyacrylic acid, polydopamine, and aramid are also applied to graphene processing. Polymers can be used as the main structural materials for fibers through physical blending or chemical polymerization, improving the mechanical strength and processability of fibers. Developing high-performance, highly practical new materials has become one of the most active research directions in materials science. Due to intermolecular forces such as electrostatic interactions, hydrophobic interactions, and van der Waals forces, polymers stably adsorbed on the graphene surface extend in solvents to form steric hindrance layers. The resulting intermolecular repulsion prevents the sheets from approaching each other. The functional groups, structure, molecular weight, concentration, and solvent properties of the polymer collectively determine its processing performance. Summary of the Invention

[0005] Based on the technical problems existing in the background art, this invention proposes a high-elongation graphene fiber and its preparation method. By developing a compound dispersant, the problem of stable and uniform dispersion of graphene liquid phase is solved. At the same time, the problem of insufficient high elongation of graphene fiber is overcome by using a molecular-mediated method. The graphene fiber finally prepared not only has excellent elongation performance, but also has uniform morphology, smooth surface and certain strength. Meanwhile, the preparation process is simple, time-saving and energy-saving.

[0006] The present invention proposes a method for preparing highly elongated graphene fibers, comprising the following steps: S1. A spinning solution is obtained by mixing graphene dispersion and polyvinyl alcohol; the graphene dispersion includes graphene and a compound dispersant, which is composed of amphoteric dispersant and nonionic dispersant. S2. The spinning solution is subjected to solution spinning to obtain graphene nascent fibers; S3. After reducing the nascent graphene fibers, carbonize them to obtain the highly elongated graphene fibers.

[0007] In this invention, to address the challenges of introducing defects into the fibers during the reduction process of graphene oxide in traditional graphene fiber preparation and the difficulty in preparing high-elongation graphene fibers, a compound dispersant composed of zwitterionic and nonionic dispersants is used. On one hand, the nonionic dispersant can effectively insert into the spaces between graphene particles, achieving good thermal stability while ensuring uniform dispersion of the graphene liquid phase at high temperatures. On the other hand, the zwitterionic dispersant contains both cationic and anionic groups, which can adsorb onto the surface of the dispersed, positively and negatively charged graphene particles in the solution, forming a stable electric double layer structure. This generates electrostatic repulsion between the graphene particles, ensuring stable dispersion over a long period. Furthermore, polyvinyl alcohol is... A water-soluble synthetic polymer, obtained by hydrolysis of polyvinyl acetate, possesses unique properties stemming from the numerous hydroxyl groups on its molecular chain. Its aqueous solution readily spins into fibers or films, achieving fiber strengths of 500-800 MPa. The hydroxyl groups can undergo esterification, crosslinking, and complexation reactions, facilitating modification or composite with other materials. Polyvinyl alcohol serves as a dispersant, toughening agent, and functional carrier, effectively addressing processing bottlenecks such as graphene dispersibility and graphene fiber brittleness. Furthermore, molecular design opens a window for multifunctionality. Graphene fibers prepared with polyvinyl alcohol exhibit weavability and biocompatibility. This invention prepares graphene fibers by mixing polyvinyl alcohol with a graphene dispersion, synergistically leveraging the properties of both to produce graphene fibers with excellent elongation properties.

[0008] Preferably, in step S1, the zwitterionic dispersant is a betaine-type zwitterionic dispersant, and the nonionic dispersant is a polyether-type nonionic dispersant. Preferably, the general structural formula of the betaine-type zwitterionic dispersant is as follows:

[0009] R1, R2, and R3 are each independently C1-C30 alkyl, alkenyl, hydroxyalkyl, amide, or ester groups, R4 is a C1-C4 alkylene group, and X is a carboxyl or sulfonic acid group. Preferably, the zwitterionic dispersant is cocamidopropyl betaine, and the nonionic dispersant is polyethylene glycol octylphenyl ether; Preferably, the mass ratio of the zwitterionic dispersant to the nonionic dispersant is 1:(0.5-2), and more preferably 1:1.

[0010] In this invention, the zwitterionic dispersant is a betaine-type zwitterionic dispersant. Compared with general zwitterionic dispersants, the former contains both cationic quaternary ammonium groups and anionic carboxylic acid or sulfonic acid groups in its molecule. It can effectively compound graphene to form an electric double layer structure, and can also be compounded with polyether-type nonionic dispersants, thereby combining the advantages of these two dispersants and inhibiting the aggregation of graphene in high-temperature solvents.

[0011] Preferably, in step S1, the mass ratio of graphene to the compound dispersant is 1:(10-20), more preferably 1:(10-15), and even more preferably 1:(10-11). Preferably, the mass ratio of graphene to polyvinyl alcohol is 1:(1-1.5), more preferably 1:(1.2-1.4).

[0012] Preferably, in step S1, the graphene dispersion is obtained by dissolving the compound dispersant in an organic solvent and then adding graphene for ultrasonic shearing dispersion. Preferably, the ultrasonic shearing dispersion includes: ultrasonication at a power of 200-400W for 10-15 minutes, followed by a 4-6 minute pause as one cycle, for a total of 2-6 cycles.

[0013] Preferably, in step S1, the mixing involves adding polyvinyl alcohol, organic solvent, and water to a graphene dispersion, followed by heating and ultrasonic stirring to form a gel. Preferably, the molecular weight of the polyvinyl alcohol is 100,000-200,000, more preferably 150,000-200,000; Preferably, the heating and ultrasonic stirring includes: stirring at a heating temperature of 50-60℃ for 1.5-2.5 hours, with ultrasonic stirring for 1.5-2.5 hours constituting one cycle, and a total of 1-3 cycles.

[0014] Preferably, in step S2, the solution spinning is achieved by extruding the spinning solution from the spinning head, entering the coagulation liquid to generate nascent filaments, then continuously drawing and stretching them, and finally taking them up through the spinning drum. Preferably, the coagulation solution is at least one selected from methanol, ethyl acetate, acetone, or isopropanol; Preferably, the continuous traction stretching includes: sequentially winding the coil into continuously operating reels with rotational speeds of 15-40 rpm / min and 30-80 rpm / min, respectively.

[0015] Preferably, in step S3, the reduction involves heating the nascent graphene fibers in a reducing atmosphere. Preferably, the reducing atmosphere is at least one of iodine vapor, hydrazine hydrate vapor, hydrogen iodide solution, or vitamin C solution; Preferably, the heating reaction includes: heating to 180-210℃, preferably 200-210℃, more preferably 205-210℃, holding at that temperature for 0.5-1.5h, preferably 1-1.5h, more preferably 80-90min, then heating to 220-240℃, preferably 230-240℃, and holding at that temperature for 4-6h, preferably 5-6h, more preferably 5.5-6h.

[0016] Preferably, in step S3, the carbonization includes: heating to 500-800℃, preferably 700-800℃, more preferably 750-800℃, and holding at that temperature for 5-30 minutes, preferably 20-30 minutes, more preferably 25-30 minutes; Preferably, the carbonization is carried out under an inert atmosphere, and more preferably under a nitrogen atmosphere.

[0017] The present invention also proposes a highly elongated graphene fiber, which is prepared by the above-described preparation method.

[0018] The beneficial effects of the high elongation graphene fiber described in this invention are as follows: (1) The dispersant prepared by compounding zwitterionic and nonionic dispersants in this invention effectively solves the problem of stable and uniform dispersion of graphene in the liquid phase, providing a basis for direct solution spinning of graphene fibers, thereby reducing irreversible structural defects caused by the reduction of graphene oxide. (2) This invention develops a graphene fiber preparation technology with polyvinyl alcohol assistance based on solution spinning, including three steps: solution spinning, iodination and carbonization, which provides a technical basis for the continuous preparation of graphene fibers; (3) The graphene fiber prepared by the ultra-high molecular weight polyvinyl alcohol assisted by the present invention has excellent elongation. The graphene fiber obtained has uniform texture and uniform pores, which provides a basis for the flexibility and weavability of graphene fiber. Attached Figure Description

[0019] Figure 1 These are scanning electron microscope images of the graphene fibers described in the embodiments and comparative examples of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0021] Example 1

[0022] A highly elongated graphene fiber is prepared by the following method: (1) 0.1 g of cocamidopropyl betaine and 0.1 g of polyethylene glycol octylphenyl ether were added to 10 mL of N,N-dimethylformamide as a compound dispersant. The mixture was ultrasonically dispersed at 200 W for 4 h, and then heated at 50 °C for 4 h to achieve stabilization. 0.01 g of graphene powder was then added for ultrasonic shear dispersion. The mixture was ultrasonically dispersed at 200 W for 15 min, with a 5 min pause as one cycle. Two cycles were repeated to obtain a graphene dispersion. (2) Add 0.01g of polyvinyl alcohol (molecular weight 124000), 20mL of N,N-dimethylformamide and 10mL of deionized water to the graphene dispersion and heat and sonicate it. Stir at 50°C for 2h, sonicate for 2h as one cycle, and cycle for one cycle. The mixed solution forms a gel-like solution to obtain the spinning solution. (3) The spinning solution is injected into a rotating coagulation bath with a rotation speed of 5 rpm / min using a syringe at a speed of 5 mL / h. The rotating coagulation bath is methanol. The solution is left to stand in the coagulation bath for 24 h. The resulting wet fibers are then wound into continuously rotating spools with rotation speeds of 15 rpm / min and 30 rpm / min, and finally wound up through a spinning bobbin with a rotation speed of 90 rpm / min to obtain graphene nascent fibers. (4) The graphene nascent fiber is placed in a vacuum drying oven with a vacuum degree of less than 1000 Pa and dried at 60°C for 12 hours. The dried fiber is placed in an iodine vapor sealed box, heated to 180°C and kept at that temperature for 0.5 hours, then heated to 220°C and kept at that temperature for 4 hours. After naturally cooling to room temperature, it is heated to 500°C in a nitrogen atmosphere and kept at that temperature for 5 minutes to obtain the high elongation graphene fiber.

[0023] Example 2

[0024] A highly elongated graphene fiber is prepared by the following method: (1) 0.2g of cocamidopropyl betaine and 0.2g of polyethylene glycol octylphenyl ether were added to 10mL of N,N-dimethylformamide as a compound dispersant. The mixture was ultrasonically dispersed at 300W for 4h, and then heated at 50℃ for 4h to achieve stabilization. 0.03g of graphene powder was then added for ultrasonic shear dispersion. The mixture was ultrasonically dispersed at 300W for 10min, with a 5min pause as one cycle. A total of 4 cycles were performed to obtain a graphene dispersion. (2) Add 0.03g of polyvinyl alcohol (molecular weight 186000), 20mL of N,N-dimethylformamide and 10mL of deionized water to the graphene dispersion and heat and sonicate it. Stir at 50°C for 2 hours and sonicate for 2 hours as one cycle. Repeat the cycle for a total of 2 cycles. The mixed solution forms a gel-like solution to obtain the spinning solution. (3) The spinning solution is injected into a rotating coagulation bath with a rotation speed of 10 rpm / min using a syringe at a speed of 10 mL / h. The rotating coagulation bath is methanol. The solution is left to stand in the coagulation bath for 24 h. The resulting wet fibers are then wound into continuously rotating spools with rotation speeds of 20 rpm / min and 40 rpm / min, and finally wound up through a spinning bobbin with a rotation speed of 120 rpm / min to obtain graphene nascent fibers. (4) The graphene nascent fiber is placed in a vacuum drying oven with a vacuum degree of less than 1000 Pa and dried at 70°C for 12 hours. The dried fiber is placed in an iodine vapor sealed box, heated to 200°C and kept at that temperature for 1 hour. Then it is heated to 230°C and kept at that temperature for 5 hours. After naturally cooling to room temperature, it is heated to 700°C in a nitrogen atmosphere and kept at that temperature for 20 minutes to obtain the high elongation graphene fiber.

[0025] Example 3

[0026] A highly elongated graphene fiber is prepared by the following method: (1) 0.3g of cocamidopropyl betaine and 0.3g of polyethylene glycol octylphenyl ether were added to 10mL of N,N-dimethylformamide as a compound dispersant. The mixture was ultrasonically dispersed at 400W for 4h, and then heated at 50℃ for 4h to achieve stabilization. 0.06g of graphene powder was then added for ultrasonic shear dispersion. The mixture was ultrasonically dispersed at 400W for 15min, with a 5min pause as one cycle. A total of 6 cycles were performed to obtain a graphene dispersion. (2) Add 0.06g of polyvinyl alcohol (molecular weight 186000), 20mL of N,N-dimethylformamide and 10mL of deionized water to the graphene dispersion and heat and sonicate it. Stir at 50°C for 2h, sonicate for 2h as one cycle, and repeat for 3 cycles. The mixed solution forms a gel-like solution to obtain the spinning solution. (3) The spinning solution is injected into a rotating coagulation bath with a rotation speed of 20 rpm / min using a syringe at a speed of 20 mL / h. The rotating coagulation bath is methanol. The solution is left to stand in the coagulation bath for 24 h. The resulting wet fibers are then wound into continuously rotating spools with rotation speeds of 40 rpm / min and 80 rpm / min, and finally wound up through a spinning bobbin with a rotation speed of 240 rpm / min to obtain graphene nascent fibers. (4) The graphene nascent fiber is placed in a vacuum drying oven with a vacuum degree of less than 1000 Pa and dried at 80°C for 12 hours. The dried fiber is placed in an iodine vapor sealed box, heated to 210°C and kept at that temperature for 1.5 hours, then heated to 240°C and kept at that temperature for 6 hours. After naturally cooling to room temperature, it is heated to 800°C in a nitrogen atmosphere and kept at that temperature for 30 minutes to obtain the high elongation graphene fiber.

[0027] Example 4

[0028] A highly elongated graphene fiber is prepared by the following method: (1) 0.3g of cocamidopropyl betaine and 0.3g of polyethylene glycol octylphenyl ether were added to 10mL of N,N-dimethylformamide as a compound dispersant. The mixture was ultrasonically dispersed at 400W for 4h, and then heated at 50℃ for 4h to achieve stabilization. 0.06g of graphene powder was then added for ultrasonic shear dispersion. The mixture was ultrasonically dispersed at 400W for 15min, with a 5min pause as one cycle. A total of 6 cycles were performed to obtain a graphene dispersion. (2) Add 0.08g of polyvinyl alcohol (molecular weight 186000), 20mL of N,N-dimethylformamide and 10mL of deionized water to the graphene dispersion and heat and sonicate it. Stir at 50°C for 2h, sonicate for 2h as one cycle, and repeat for 3 cycles. The mixed solution forms a gel-like solution to obtain the spinning solution. (3) The spinning solution is injected into a rotating coagulation bath with a rotation speed of 20 rpm / min using a syringe at a speed of 20 mL / h. The rotating coagulation bath is methanol. The solution is left to stand in the coagulation bath for 24 h. The resulting wet fibers are then wound into continuously rotating spools with rotation speeds of 40 rpm / min and 80 rpm / min, and finally wound up through a spinning bobbin with a rotation speed of 240 rpm / min to obtain graphene nascent fibers. (4) The graphene nascent fiber is placed in a vacuum drying oven with a vacuum degree of less than 1000 Pa and dried at 80°C for 12 hours. The dried fiber is placed in an iodine vapor sealed box, heated to 210°C and kept at that temperature for 1.5 hours, then heated to 240°C and kept at that temperature for 6 hours. After naturally cooling to room temperature, it is heated to 800°C in a nitrogen atmosphere and kept at that temperature for 30 minutes to obtain the high elongation graphene fiber.

[0029] Example 5

[0030] A highly elongated graphene fiber is prepared by the following method: (1) 0.3g of sodium dodecylaminopropionate and 0.3g of polyoxyethylene octadecylamine were added to 10mL of N,N-dimethylformamide as a compound dispersant. The mixture was ultrasonically dispersed at 400W for 4h, and then heated at 50℃ for 4h to achieve stabilization. Then, 0.06g of graphene powder was added for ultrasonic shear dispersion. The mixture was ultrasonically dispersed at 400W for 15min, with a 5min pause as one cycle. A total of 6 cycles were performed to obtain a graphene dispersion. (2) Add 0.06g of polyvinyl alcohol (molecular weight 186000), 20mL of N,N-dimethylformamide and 10mL of deionized water to the graphene dispersion and heat and sonicate it. Stir at 50°C for 2h, sonicate for 2h as one cycle, and repeat for 3 cycles. The mixed solution forms a gel-like solution to obtain the spinning solution. (3) The spinning solution is injected into a rotating coagulation bath with a rotation speed of 20 rpm / min using a syringe at a speed of 20 mL / h. The rotating coagulation bath is methanol. The solution is left to stand in the coagulation bath for 24 h. The resulting wet fiber is then wound into a continuously rotating spool with a rotation speed of 40 rpm / min and 80 rpm / min in sequence. Finally, the fiber is wound up through a spinning bobbin with a rotation speed of 240 rpm / min to obtain graphene nascent fiber. (4) The graphene nascent fiber is placed in a vacuum drying oven with a vacuum degree of less than 1000 Pa and dried at 80°C for 12 hours. The dried fiber is placed in an iodine vapor sealed box, heated to 210°C and kept at that temperature for 1.5 hours, then heated to 240°C and kept at that temperature for 6 hours. After naturally cooling to room temperature, it is heated to 800°C in a nitrogen atmosphere and kept at that temperature for 30 minutes to obtain the high elongation graphene fiber.

[0031] Comparative Example 1 A graphene fiber is prepared by the preparation method described in Example 3, except that in step (1), only 0.3 g of cocamidopropyl betaine is added as a dispersant to 10 mL of N,N-dimethylformamide.

[0032] Comparative Example 2 A graphene fiber is prepared by the preparation method described in Example 3, except that in step (1), only 0.3g of hexadecyltrimethylammonium bromide and 0.3g of sodium dodecyl sulfonate are added as compound dispersants to 10mL of N,N-dimethylformamide.

[0033] Comparative Example 3 A graphene fiber is prepared by the preparation method described in Example 3, except that in step (2), 0.06 g of polyacrylonitrile (molecular weight 100,000), 20 mL of N,N-dimethylformamide and 10 mL of deionized water are added to the graphene dispersion and heated and ultrasonically stirred. Performance testing: The graphene fibers described in the above embodiments and comparative examples were scanned using a scanning electron microscope, and the resulting images are shown below. Figure 1 As shown: Reference Figure 1It can be seen that spinning was successful in Examples 1-4. However, due to the slightly insufficient amount of compound dispersant added in Examples 1 and 2, the fiber diameter was not very uniform. The fiber state in Examples 3 and 4 was better, with a more uniform diameter and a relatively smooth surface. Example 5 used a non-betaine-type zwitterionic dispersant and a polyether-type nonionic dispersant as compound dispersants, and the fiber spinning was acceptable, but the fiber diameter was uneven. In Comparative Example 1, since only one dispersant was added, the dispersion effect was not good. Fine filaments could be formed, but they were easy to break. Comparative Example 2 used other compound dispersants, and the fiber diameter was more uniform, and the dispersion effect was acceptable, but they were easy to break and could not form long filaments. In Comparative Example 3, polyacrylonitrile was used instead of polyvinyl alcohol, and the fiber spinning was more difficult and it was easy to break.

[0034] The elongation and tensile strength of the graphene fibers described in the examples and comparative examples were tested, and the results are shown in Table 1 below: Table 1. Performance test results of the graphene fibers described in the examples and comparative examples.

[0035] As can be seen from Table 1, compared with Examples 1 and 2, the graphene fibers described in Examples 3 and 4 have better elongation and tensile strength, because the latter have sufficient addition of compound dispersant. Compared with Example 3, the graphene fibers described in Example 5 have much lower elongation and tensile strength, because the latter uses non-betaine-type zwitterionic dispersant and polyether-type nonionic dispersant as compound dispersants. It can be seen that among compound dispersants, betaine-type zwitterionic dispersants are better for improving the elongation performance of graphene fibers, because the latter also contains quaternary ammonium cations, which have a better adsorption effect on negatively charged graphene particles.

[0036] Compared with Comparative Examples 1 and 2, the graphene fibers described in Example 3 not only exhibit better elongation and tensile strength, but also demonstrate superior dispersion stability in the resulting graphene dispersion. In actual research and development, the inventors discovered that while using amphoteric or nonionic dispersants, or a combination of anionic or cationic dispersants with nonionic dispersants, can disperse graphene particles to some extent, the graphene tends to separate and precipitate over time. However, if the composite dispersant of amphoteric and nonionic dispersants described in Example 3 is used, the resulting graphene dispersion can be stored for two weeks without separation or precipitation.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing highly elongated graphene fibers, characterized in that, Includes the following steps: S1. A spinning solution is obtained by mixing graphene dispersion and polyvinyl alcohol; the graphene dispersion includes graphene and a compound dispersant, which is composed of amphoteric dispersant and nonionic dispersant. S2. The spinning solution is subjected to solution spinning to obtain graphene nascent fibers; S3. After reducing the nascent graphene fibers, carbonize them to obtain the highly elongated graphene fibers.

2. The method for preparing high-elongation graphene fibers according to claim 1, characterized in that, In step S1, the zwitterionic dispersant is a betaine-type zwitterionic dispersant, and the nonionic dispersant is a polyether-type nonionic dispersant. Preferably, the general structural formula of the betaine-type zwitterionic dispersant is as follows: R1, R2, and R3 are each independently C1-C30 alkyl, alkenyl, hydroxyalkyl, amide, or ester groups, R4 is a C1-C4 alkylene group, and X is a carboxyl or sulfonic acid group. Preferably, the zwitterionic dispersant is cocamidopropyl betaine, and the nonionic dispersant is polyethylene glycol octylphenyl ether; Preferably, the mass ratio of the zwitterionic dispersant to the nonionic dispersant is 1:(0.5-2).

3. The method for preparing highly elongated graphene fibers according to claim 1 or 2, characterized in that, In step S1, the mass ratio of graphene to the compound dispersant is 1:(10-20). Preferably, the mass ratio of graphene to polyvinyl alcohol is 1:(1-1.5).

4. The method for preparing highly elongated graphene fibers according to any one of claims 1-3, characterized in that, In step S1, the graphene dispersion is obtained by dissolving the compound dispersant in an organic solvent and then adding graphene for ultrasonic shearing dispersion. Preferably, the ultrasonic shearing dispersion includes: ultrasonication at a power of 200-400W for 10-15 minutes, followed by a 4-6 minute pause as one cycle, for a total of 2-6 cycles.

5. The method for preparing highly elongated graphene fibers according to any one of claims 1-4, characterized in that, In step S1, the mixing involves adding polyvinyl alcohol, organic solvent, and water to a graphene dispersion, followed by heating and ultrasonic stirring to form a gel. Preferably, the molecular weight of the polyvinyl alcohol is 100,000-200,000; Preferably, the heating and ultrasonic stirring includes: stirring at a heating temperature of 50-60℃ for 1.5-2.5 hours, with ultrasonic stirring for 1.5-2.5 hours constituting one cycle, and a total of 1-3 cycles.

6. The method for preparing highly elongated graphene fibers according to any one of claims 1-5, characterized in that, In step S2, the solution spinning involves extruding the spinning solution from the spinning head, entering the coagulation liquid to generate nascent filaments, then continuously drawing and stretching them, and finally taking them up through a spinning drum. Preferably, the coagulation solution is at least one selected from methanol, ethyl acetate, acetone, or isopropanol; Preferably, the continuous traction stretching includes: sequentially winding the coil into continuously operating reels with rotational speeds of 15-40 rpm / min and 30-80 rpm / min, respectively.

7. The method for preparing highly elongated graphene fibers according to any one of claims 1-6, characterized in that, In step S3, the reduction involves heating the nascent graphene fibers in a reducing atmosphere. Preferably, the reducing atmosphere is at least one of iodine vapor, hydrazine hydrate vapor, hydrogen iodide solution, or vitamin C solution; Preferably, the heating reaction includes: heating to 180-210°C, holding at that temperature for 0.5-1.5 hours, and then heating to 220-240°C and holding at that temperature for 4-6 hours.

8. The method for preparing highly elongated graphene fibers according to any one of claims 1-7, characterized in that, In step S3, the carbonization includes: heating to 500-800℃ and holding at that temperature for 5-30 minutes; Preferably, the carbonization is carried out under an inert atmosphere.

9. A highly elongated graphene fiber, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the highly elongated graphene fiber of claim 9 in flexible electronic devices.

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