Molecularly doped sugar-based multifunctional carbon fibers and methods for making the same

Abstract

The application discloses a kind of molecularly doped glycosyl multifunctional carbon fibers and preparation method thereof, belong to carbon fiber preparation technical field.The application is by with water-soluble saccharide, gel monomer and spinning auxiliary agent as main raw material, using both can help fiber solidification, and can incorporate ionic gel auxiliary agent preparation coagulation bath of functional molecule, by wet spinning and drying in situ preparation including multifunctional molecule carbon fiber protofilament, after pre-carbonization and carbonization processing realizes the efficient synthesis of molecularly doped multifunctional carbon fiber.The introduction of multifunctional molecule significantly improves the comprehensive performance of carbon fiber, including high temperature resistance, oxidation resistance, corrosion resistance, high strength, high conductivity, high thermal conductivity and high specific surface area.Because of its high conductivity, high specific surface area and oxidation resistance, with the support of in-situ introduction of high pseudocapacitance material, it provides a strong material foundation for the wide application of flexible fiber-like supercapacitors.This technical breakthrough will help to realize efficient and durable energy storage solutions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon fiber preparation, and particularly relates to a molecularly doped sugar-based multifunctional carbon fiber and a preparation method thereof. BACKGROUND

[0002] Traditional carbon fibers have excellent properties such as high strength, high modulus, light weight, high temperature resistance, corrosion resistance, and are widely used in aerospace, automobile manufacturing, wind power blades, sports equipment and building reinforcement, etc., which can significantly improve the structural performance and durability of materials.

[0003] However, traditional carbon fibers have significant limitations in multifunctionalization, and it is difficult to directly introduce multifunctional phases in the preparation of the original fiber. Usually, only secondary functionalization treatment of the finished carbon fiber can be achieved, which not only relies on toxic and harmful substances, increases the environmental burden, but also makes the process more complex. In addition, the preparation process of traditional polyacrylonitrile (PAN) based carbon fibers is complex and energy intensive, requiring multiple high-temperature carbonization steps, which limits the yield and cost; the emission of harmful gases during the preparation process and the difficulty of recycling also have adverse effects on the environment. Moreover, the main raw materials of carbon fibers rely on non-renewable fossil resources such as PAN and pitch, which consume a large amount of resources. The above problems limit the application potential of carbon fibers in multifunctional composite materials such as conductive, thermal and energy storage, and new methods are needed to promote their multifunctionalization and sustainable development. SUMMARY

[0004] The purpose of the present application is to provide a molecularly doped sugar-based multifunctional carbon fiber and a preparation method thereof. By using water-soluble sugars, gel monomers and spinning aids as main raw materials, an ionic gel aid that can help fiber coagulation and incorporate functional molecules is used to prepare a coagulation bath, and carbon fiber original silk containing multifunctional molecules is prepared in situ through wet spinning and drying, and then pre-carbonization and carbonization treatment are carried out to realize the efficient synthesis of molecularly doped multifunctional carbon fiber. Compared with traditional carbon fibers that need to be functionally modified in the later stage, the present application can directly incorporate functional molecules in the preparation of the original silk, making the functional molecules uniformly distributed, significantly simplifying the process, reducing energy consumption, not relying on non-renewable fossil resources, and having the advantages of green environmental protection, simple operation, etc.

[0005] To achieve the above purpose, the present application provides the following technical scheme:

[0006] One of the technical schemes of the present application: a preparation method of a molecularly doped sugar-based multifunctional carbon fiber is provided, comprising the following steps:

[0007] Dissolve the gel monomer, water-soluble sugar and crosslinking agent in water to obtain solution A; add the spinning aid, initiator and catalyst to the solution A as the spinning liquid;

[0008] A solution identical to the solution A is prepared, and an ionic gel additive is added as a coagulation bath;

[0009] A solution in which the gel monomer, the crosslinking agent, and the spinning aid in the spinning solution are omitted is used as a water bath solution;

[0010] A multifunctional carbon fiber precursor is obtained by wet spinning using the spinning solution, the coagulation bath, and the water bath solution;

[0011] The multifunctional carbon fiber precursor is first pre-carbonized to obtain a pre-carbonized multifunctional fiber, and the pre-carbonized multifunctional fiber is then carbonized to obtain the molecularly doped sugar-based multifunctional carbon fiber;

[0012] The ionic gel additive includes lanthanum chloride, cerium nitrate, yttrium nitrate, copper formate tetrahydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, nickel nitrate hexahydrate, zirconium chloride, iron chloride, zirconium oxychloride, hafnium oxychloride, zirconium sulfate, titanium sulfate, titanium nitrate, or zirconium acetate.

[0013] The present application uses water-soluble sugars, gel monomers, and spinning aids as main raw materials, and incorporates functional molecules by using specific ionic gel additives, and in-situ prepares carbon fiber precursors containing multifunctional molecules through wet spinning and drying. The coagulation bath and the water bath solution prepared in the wet spinning process can be recycled multiple times. The present application incorporates multifunctional molecules in the raw fiber preparation stage; then removes volatile matter and moisture through pre-carbonization, promotes caramelization, reduces internal stress, avoids cracking and breaking, completes stabilization treatment, ensures fiber uniformity and strength; and finally obtains multifunctional carbon fibers doped at the molecular level through carbonization.

[0014] Optionally, the gel monomer includes one or more of acrylamide, acrylic acid, methacrylic acid, polyethylene glycol diacrylate, and N-isopropyl acrylamide.

[0015] Optionally, the water-soluble sugar includes one or more of glucose, fructose, galactose, maltose, sucrose, lactose, and fructooligosaccharide.

[0016] Optionally, the crosslinking agent includes one or more of N,N'-methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diacrylamidoethylenediamine, polyethylene glycol diacrylate, trimethylolpropane triacrylate, divinyl urea, N,N'-ethylenebisacrylamide, and N,N'-bis(acryloyloxyethyl) urea.

[0017] Preferably, the mass ratio of the gel monomer, the water-soluble sugar, the crosslinking agent, and water in the solution A is 1-20:10-60:0.05-2:100.

[0018] Optionally, the spinning aid includes one or more of sodium alginate, sodium polyacrylate, and sodium carboxymethyl cellulose.

[0019] Optionally, the initiator includes one or more of ammonium persulfate, azobisisobutyronitrile, potassium persulfate, and hydrogen peroxide.

[0020] Optionally, the catalyst includes one or more of triethanolamine, sodium bisulfite, and tetramethylethylenediamine.

[0021] Preferably, in the spinning solution, the spinning aid, initiator, and catalyst are added in the form of aqueous solutions, wherein the concentration of the spinning aid aqueous solution is 1-10 wt.%, the concentration of the initiator aqueous solution is 0.5-20 wt.%, and the concentration of the catalyst aqueous solution is 0.5-20 wt.%.

[0022] Preferably, in the spinning solution, the mass ratio of the spinning aid to water in the solution A is 0.5-5:100.

[0023] In the spinning solution, the amount of initiator and catalyst added is determined according to the amount of gel monomer, and the conventional amount in the art is added.

[0024] Preferably, the ionic gel aid accounts for 1-20% of the mass of the coagulation bath.

[0025] Preferably, in the wet spinning process, the temperature of the water bath solution is 25-90°C.

[0026] Preferably, in the wet spinning process, the process parameters are as follows: the inner hole diameter of the spinning needle is 30-200 μm, the spinning speed is 50-2000 μL / min, the drawing machine speed is 1-20 m / min, the drying temperature is 50-300°C, and the drying time is 1-30 min.

[0027] Preferably, the pre-carbonization is gradient heating, and the highest temperature does not exceed 350°C.

[0028] More specifically, the operation steps are as follows: the multifunctional carbon fiber precursor is gradually heated in a continuous pre-carbonization furnace and passes through each temperature zone in a uniform traction manner, realizing stable pre-carbonization and obtaining pre-carbonized fibers with uniform quality; the wire speed is preferably 0.02-1 m / min to ensure that the fiber gradually adapts to the heating process, avoids damage to the internal structure, and allows the precursor to have sufficient residence time in each temperature zone for reaction to form an ideal micro-nano structure.

[0029] Preferably, the carbonization is carried out under anaerobic conditions, and direct or gradient heating is carried out to 800-3000°C at a heating rate of 1-20°C / min, and the holding time of each gradient is 0.5-6 h.

[0030] The second technical solution of the present application provides a green low-cost sugar-based multifunctional carbon fiber prepared according to the preparation method of the green low-cost sugar-based multifunctional carbon fiber.

[0031] The third technical solution of the present application provides a graphite fiber obtained by graphitizing the pre-carbonized multifunctional fiber or the molecularly doped sugar-based multifunctional carbon fiber prepared according to the preparation method.

[0032] Preferably, the graphitization temperature is 2000-3000℃, the heating rate is 0.5-20℃ / min, and the holding time is 0.5-6h.

[0033] The beneficial technical effects of the present application are as follows:

[0034] The present application innovatively proposes a carbon fiber preparation method of directly incorporating multifunctional molecules in the raw fiber preparation stage to solve the problems of long cycle, complex process, high energy consumption, serious pollution and strong dependence on non-renewable fossil resources in the traditional carbon fiber preparation process. The method uses water-soluble sugars, gel monomers and spinning aids as raw materials to prepare raw fibers containing multifunctional molecules by wet spinning, and realizes the efficient synthesis of molecularly doped multifunctional carbon fibers through pre-carbonization and carbonization steps. The introduction of multifunctional molecules significantly improves the comprehensive performance of carbon fibers, including high temperature resistance, oxidation resistance, corrosion resistance, high strength, high electrical conductivity, high thermal conductivity and high specific surface area. These characteristics not only make carbon fibers have broad application prospects in aerospace, automobile industry, electronic equipment, energy field, construction engineering, medical devices and environmental protection, but also provide a strong material foundation for the wide application of flexible fiber-shaped supercapacitors with the support of in-situ introduction of high pseudocapacitance substances due to their high electrical conductivity, high specific surface area and oxidation resistance. This technical breakthrough will help to realize efficient and durable energy storage solutions. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a picture of the continuous wet spinning collection production line used in the embodiment of the present application.

[0036] Figure 2 It is a picture of the continuous pre-carbonization furnace used in the embodiment of the present application.

[0037] Figure 3 It is a picture of the equipment for carbonization or graphitization in the embodiment of the present application.

[0038] Figure 4 It is a picture of the continuous pre-carbonization furnace temperature setting in Example 1.

[0039] Figure 5 It is a picture of the nano-copper reinforced porous carbon fiber prepared in Example 1.

[0040] Figure 6SEM images of the porous carbon fiber reinforced with nano-copper prepared in Example 1, wherein (a) is a cross-sectional morphology image, and (b) is a surface morphology image. DETAILED DESCRIPTION

[0041] The following detailed description of various example embodiments of the application is not to be considered limiting of the scope of the application, but rather a description of certain example aspects, features and embodiments of the application. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application.

[0042] Further, for numerical ranges specified in the present application, it is intended that every numerical value within the range is also specifically included. For example, a range of 1 to 5 is intended to include every possible combination of these values, i.e., the range "1 to 5" is specifically intended to include "1-5," "1, 2, 3, 4, and 5," and 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, 3-4, 3-5, and 4-5. Each smaller range is also specifically included within the application. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described herein.

[0044] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.

[0045] The wet spinning continuous collection production line in the embodiments of the application is shown in Figure 1 .

[0046] The picture of the continuous pre-carbonization furnace used in the embodiments of the application is shown in Figure 2 .

[0047] The equipment for carbonization or graphitization in the embodiments of the application is shown in Figure 3 .

[0048] Example 1

[0049] (1) Preparation of the spinning solution: first, 42 g of acrylamide, 140 g of maltose and 2.3 g of polyethylene glycol diacrylate were mixed and dissolved in 385 mL of deionized water to form a uniform transparent solution. Then 175 mL of 6% sodium alginate aqueous solution, 14 mL of 10% hydrogen peroxide aqueous solution, and 14 mL of 10% sodium bisulfite solution were added, and a uniform solution was obtained by ultrasonic and stirring. The bubbles in the spinning solution were removed by a bubble removing machine to obtain the spinning solution for use.

[0050] (2) Preparation of coagulation bath: Take acrylamide 1800g, maltose 6000g, and ethylene glycol bisacrylate 150g, copper formate 1800g, and dissolve them in 16500mL deionized water. Stir to form a uniform transparent solution in the coagulation bath tank. Open the circulating pump of the coagulation bath tank during the spinning operation to make the coagulation bath circulate in the coagulation bath tank. In addition, the coagulation bath can be used repeatedly after preparation.

[0051] (3) Preparation of water bath solution: Maltose 6000g, 600mL of 10% hydrogen peroxide aqueous solution, 600mL of 10% sodium bisulfite aqueous solution, and dissolve them in 16500mL deionized water. Stir to form a uniform transparent solution in the constant temperature water bath tank. Open the heating device of the constant temperature water bath tank during the spinning operation to make the water bath tank temperature stable at 60℃. In addition, the water bath solution can be used repeatedly after preparation.

[0052] (4) Preparation of carbon fiber precursor: Use a syringe to suck the prepared spinning solution, connect the spinning needle, and the inner hole diameter of the spinning needle is 80μm. Then use a high-precision injection pump to inject the spinning solution into the coagulation bath through the spinning needle at a speed of 600μL / min, to generate a gel fiber. The gel fiber passes through the 60℃ constant temperature water washing tank under the action of the drafting machine at a speed of 9m / min, enters the 140℃ air drying machine, and finally is collected into a bundle by the yarn collecting rod to obtain the carbon fiber precursor.

[0053] (5) Pre-carbonization: The carbon fiber precursor is passed through the continuous pre-carbonization furnace at a speed of 0.2m / min by the yarn releasing machine and the drafting machine. The precursor passes through each temperature zone in a uniform drafting manner to achieve stable pre-carbonization and obtain pre-carbonized fibers with uniform quality. The pre-carbonization production line is designed with 5 furnace bodies, each with 5 temperature zones, a total of 25 temperature zones, from 25℃ to 220℃. The temperature zones are distributed from low temperature, medium temperature to high temperature, gradually removing volatile matter and water, promoting caramelization reaction, and completing the final stabilization treatment to ensure fiber uniformity and strength. The temperature zone setting of the continuous pre-carbonization furnace is shown in Figure 4 .

[0054] (6) Carbonization: The pre-carbonized fibers are carbonized in a carbonization furnace under vacuum conditions at a heating rate of 4℃ / min, heated to 800℃, and kept for 2h, then cooled to room temperature to obtain nano-copper reinforced porous carbon fibers.

[0055] The picture of the nano-copper reinforced porous carbon fibers prepared in Example 1 is shown in Figure 5 .

[0056] The SEM image of the nano-copper reinforced porous carbon fibers prepared in Example 1 is shown in Figure 6wherein (a) is a cross-sectional morphology diagram, and (b) is a surface morphology diagram. The introduction of nano-copper significantly improves the electrical conductivity of the porous carbon fiber, up to 3284 S / m, which is due to the excellent electrical conductivity of nano-copper and its uniform distribution in the carbon fiber matrix, thereby improving the electron transport efficiency. At the same time, the existence of the porous structure not only greatly increases the specific surface area of the carbon fiber, but also provides more adsorption and diffusion paths for electrolyte ions, further enhancing the electrochemical activity. The synergistic effect of electrical conductivity and porous structure provides a strong material foundation for the wide application of flexible fiber-shaped supercapacitors, helping to achieve breakthroughs in high energy density and high power density in the field of energy storage.

[0057] It can be seen from Figure 6 The cross-sectional morphology diagram of the nano-copper enhanced porous carbon fiber shows a clear porous structure, and the pores are uniformly distributed in the carbon fiber, significantly increasing the specific surface area; the surface morphology diagram shows that there are a large number of high-contrast white spots on the surface, which are uniformly distributed nano-copper particles, and the low-contrast dark gray area is the carbon fiber matrix. The introduction of nano-copper particles effectively enhances the electrical conductivity of the carbon fiber, and its high electrical conductivity significantly improves the electron transport efficiency, while the porous structure provides a larger contact area and transmission path for electrolyte ions, forming an efficient ion channel and electronic network. This structural feature enables the nano-copper enhanced porous carbon fiber to exhibit excellent energy storage performance in the field of flexible fiber-shaped supercapacitors, laying a solid material foundation for achieving high energy density and high power density.

[0058] Example 2

[0059] (1) Prepare the spinning solution: First, dissolve 42 g of acrylic acid, 140 g of glucose and 2.3 g of ethylene glycol diacrylate in 385 mL of deionized water, and stir to form a uniform transparent solution. Then add 175 mL of 4% sodium alginate aqueous solution, 14 mL of 10% ammonium persulfate aqueous solution, and 14 mL of 10% tetramethyl ethylenediamine aqueous solution, and ultrasonic and stir to form a uniform solution. Remove the bubbles in the spinning solution by a bubble removal machine to obtain the spinning solution for use.

[0060] (2) Prepare the coagulation bath: Dissolve 1800 g of acrylic acid, 6000 g of glucose, 150 g of ethylene glycol diacrylate, and 1800 g of zirconium oxychloride in 16500 mL of deionized water, and stir to form a uniform transparent solution in the coagulation bath tank. During the spinning process, open the circulation pump of the coagulation bath tank to make the coagulation bath circulate directionally in the coagulation bath tank. In addition, the coagulation bath can be used multiple times after preparation.

[0061] (3) Preparation of water bath solution: 6000 g of glucose, 600 mL of 10% ammonium persulfate aqueous solution, 600 mL of 10% tetramethyl ethylenediamine aqueous solution, mixed and dissolved in 16500 mL of deionized water, stirred to form a uniform transparent solution in a constant temperature water bath, and the heating device of the constant temperature water bath was turned on during the spinning operation to stabilize the water bath temperature at 70°C. In addition, the water bath solution can be recycled after preparation.

[0062] (4) Carbon fiber precursor preparation: use a syringe to suck the prepared spinning solution, connect a spinning needle with an inner hole diameter of 80 μm. Then use a high-precision injection pump to inject the spinning solution into the coagulation bath at a speed of 500 μL / min through the spinning needle to generate a gel precursor. The gel precursor passes through the 70°C constant temperature water bath under the action of the drafting machine at a speed of 8 m / min, enters the 120°C air drying machine for drying, and finally is collected into a bundle by the yarn collecting rod to obtain the carbon fiber precursor.

[0063] (5) Pre-carbonization: pass the carbon fiber precursor through the continuous pre-carbonization furnace at a speed of 0.05 m / min by the yarn releasing machine and the drafting machine. The precursor passes through each temperature zone in a uniform manner to realize stable pre-carbonization and obtain pre-carbonized fibers with uniform mass. The pre-carbonization production line is designed with 5 furnace bodies, each of which has 5 temperature zones, a total of 25 temperature zones, gradually increasing from 25°C to 220°C. The temperature zones are distributed from low temperature, medium temperature to high temperature, gradually removing volatile matter and water, promoting caramelization reaction, and completing the final stabilization treatment to ensure fiber uniformity and strength. The temperature zone setting of the continuous pre-carbonization furnace is shown in Figure 4 .

[0064] (6) Carbonization: use a carbonization furnace to carbonize the pre-carbonized fibers. Under vacuum conditions, the temperature is increased to 360°C, 920°C, 1050°C and 1400°C at a rate of 4°C / min, respectively, and each is kept for 2 h, and then the furnace is cooled to room temperature to obtain nano-zirconia reinforced carbon fibers.

[0065] The oxidation initiation temperature of the nano-zirconia reinforced carbon fibers prepared in Example 2 is as high as 748°C.

[0066] The above examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for preparing a green, low-cost, sugar-based multifunctional carbon fiber, characterized in that, Includes the following steps: Dissolve the gel monomer, water-soluble sugar, and cross-linking agent in water to obtain solution A; Add spinning aid, initiator and catalyst to solution A to prepare spinning solution; Prepare a solution identical to solution A, and add an ion gelation aid as a coagulation bath; A solution omitting the gel monomer, crosslinking agent, and spinning aid in the spinning solution is used as the water bath solution; Multifunctional carbon fiber precursor is obtained by wet spinning using the spinning solution, the coagulation bath, and the water bath solution. The multifunctional carbon fiber precursor is first pre-carbonized to obtain pre-carbonized multifunctional fiber; then the pre-carbonized multifunctional fiber is carbonized to obtain the green, low-cost sugar-based multifunctional carbon fiber. The gel monomer includes one or more of acrylamide, acrylic acid, methacrylic acid, polyethylene glycol diacrylate, and N-isopropylacrylamide; The water-soluble sugars include one or more of glucose, fructose, galactose, maltose, sucrose, lactose, and fructooligosaccharides. The crosslinking agent includes one or more of N,N'-methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diacrylamide ethylenediamine, polyethylene glycol diacrylate, trimethylolpropane triacrylate, divinyl urea, N,N'-ethylenebisacrylamide, and N,N'-bis(acryloyloxyethyl)urea; The ion gel additives include lanthanum chloride, cerium nitrate, yttrium nitrate, copper formate tetrahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, nickel nitrate hexahydrate, zirconium chloride, ferric chloride, zirconium oxychloride, hafnium oxychloride, zirconium sulfate, titanium sulfate, titanium nitrate, or zirconium acetate.

2. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, The mass ratio of gel monomer, water-soluble sugar, cross-linking agent and water in solution A is 1-20:10-60:0.05-2:

100.

3. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, In the spinning solution, the spinning aid, initiator, and catalyst are added in the form of aqueous solutions, wherein the concentration of the aqueous solution of the spinning aid is 1-10 wt.%, the concentration of the aqueous solution of the initiator is 0.5-20 wt.%, and the concentration of the aqueous solution of the catalyst is 0.5-20 wt.%.

4. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, In the spinning solution, the mass ratio of the spinning aid to water in solution A is 0.5 to 5:

100.

5. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, The ion gelation aid accounts for 1 to 20% of the mass of the coagulation bath.

6. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, During the wet spinning process, the process parameters are as follows: inner diameter of spinning needle 30-200 μm, spinning speed 50-2000 μL / min, drawing machine speed 1-20 m / min, drying temperature 50-300℃, and drying time 1-30 min.

7. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, The pre-carbonization is carried out by gradient heating, with the maximum temperature not exceeding 350°C.

8. The method for preparing green, low-cost, sugar-based multifunctional carbon fiber according to claim 1, characterized in that, The carbonization is carried out under oxygen-free conditions, with direct or gradient heating to 800–3000°C at a rate of 1–20°C / min, and holding time for each gradient being 0.5–6 h.

9. A green, low-cost, sugar-based multifunctional carbon fiber prepared by the method of any one of claims 1 to 8.

10. A graphite fiber, characterized in that, The graphitization is performed on pre-carbonized multifunctional fibers or molecularly doped sugar-based multifunctional carbon fibers prepared by the preparation method according to any one of claims 1 to 8.

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