Carbon-based nanofiber membrane as well as preparation method and application thereof

Abstract

The invention relates to a carbon-based nanofiber membrane as well as a preparation method and application thereof. According to the technical scheme, the preparation method comprises the following steps: dissolving a biomass carbon source, a conductive enhancer and a cross-linking agent in an organic solvent according to the mass ratio of the biomass carbon source to the conductive enhancer to the cross-linking agent being 1: (0.1-0.5): (0.05-0.2), and uniformly stirring to obtain a spinning solution; and carrying out electrostatic spinning to obtain the precursor fiber membrane. In the air atmosphere, tension is applied to the precursor fiber membrane, then pre-oxidation treatment is conducted, the temperature is increased to 200-300 DEG C at the speed of 1-5 C / min, heat preservation is conducted, and a pre-oxidized fiber membrane is obtained; and carrying out carbonization treatment on the pre-oxidized fiber membrane in an inert atmosphere: heating to 800-1200 DEG C at the speed of 2-10 DEG C / min, and carrying out heat preservation to obtain the carbon-based nanofiber membrane. The method is simple in process, low in cost and environment-friendly; the prepared product has the characteristics of high conductivity, high specific surface area and excellent mechanical property, and is widely applied to the fields of flexible electrodes, supercapacitors, lithium ion batteries and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanofiber membrane technology. Specifically, it relates to a carbon-based nanofiber membrane, its preparation method, and its applications. Background Technology

[0002] Carbon-based nanofiber membranes, due to their unique three-dimensional network structure, high specific surface area, excellent chemical stability, and tunable conductivity, have shown great application potential in fields such as flexible electronic devices, supercapacitors, lithium-ion batteries, adsorption filtration, and catalysis. Currently, the main methods for preparing carbon-based nanofiber membranes include chemical vapor deposition (CVD) and electrospinning, with electrospinning having attracted the attention of those skilled in the art.

[0003] For example, the patented technology "A polyacrylonitrile-based carbon fiber membrane and its preparation method and application" (CN117646294A) uses PAN as raw material to produce carbon fiber membranes through electrospinning, pre-oxidation, and carbonization. Although this technology is relatively mature and the fiber morphology is controllable, it has the following technical defects: First, synthetic polymers such as polyacrylonitrile (PAN) are expensive, resulting in high raw material costs; second, the pre-oxidation process (cyclization stabilization of PAN) is extremely time-consuming (usually several hours) and energy-intensive, which is the bottleneck of the entire production process; third, the final carbon fiber exhibits inherent brittleness, and its mechanical properties, especially flexibility and elongation at break, are poor, making it difficult to meet the requirements of repeated bending in flexible devices.

[0004] For example, the patented technology of "A method for preparing a highly flexible integral carbon nanofiber membrane" (CN112430851A) involves refluxing coke powder with a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, washing and drying it to obtain oxidized coke powder. Using the oxidized coke powder as raw material, PVB and / or PVP as spinning aids and pore-forming agents, a highly flexible integral carbon nanofiber membrane is obtained through electrospinning, pre-oxidation and carbonization. However, this method corrodes equipment and pollutes the environment.

[0005] For example, the patented technology "A method for preparing and applying a type of supramolecular carbon film based on electrospinning" (CN114059230A) uses electrospinning to co-spin PAN with γ-cyclodextrin metal-organic framework (γ-CD-MOF), and then carbonizes it at 900℃. Although a PAN / γ-CD-MOF supramolecular carbon film is obtained, the secondary bonding interface of this method is unstable and the production cost is high.

[0006] For example, the patented technology of "Preparation method of acid-modified graphene-doped polyacrylonitrile-based composite activated carbon nanofiber" (CN120330924A) uses modified multilayer graphene and polyacrylonitrile chemical composite and electrospinning technology to prepare nanofiber composite films. However, this method uses highly corrosive chemical reagents for post-activation treatment to increase the specific surface area, which corrodes equipment, pollutes the environment, and seriously damages the mechanical strength of the fibers.

[0007] For example, the patented technology "A method for supercritical assisted deposition to modify carbon aerogel materials and the materials obtained by the method" (CN117585981A) produces carbon aerogels through supercritical drying or freeze drying, but the equipment is expensive, the energy consumption is extremely high, and it is difficult to prepare continuous films.

[0008] In addition, existing technologies heavily rely on non-renewable petrochemical resources. Although some studies have attempted to use biomass (such as lignin and cellulose) as a carbon source, the carbon fibers obtained after direct carbonization often suffer from structural collapse, low specific surface area, poor electrical conductivity and mechanical properties due to the weak intermolecular forces and complex thermal behavior of biomass molecules. As a result, they are difficult to directly replace PAN-based carbon fibers for high-performance applications.

[0009] Therefore, the existing technology has the following technical defects: high raw material cost, high energy consumption and time cost in the pre-oxidation process, and insufficient fiber flexibility; complicated process, interface bonding problem affects performance stability; performance (conductivity, mechanical strength) is difficult to meet application requirements; strong dependence on non-renewable resources, and low degree of greening of the entire preparation process. Summary of the Invention

[0010] This invention aims to overcome the shortcomings of existing technologies and provide a simple, low-cost, environmentally friendly method for preparing carbon-based nanofiber membranes suitable for large-scale production. The carbon-based nanofiber membranes prepared by this method have high conductivity, high specific surface area and excellent mechanical properties, and can be widely used in flexible electrodes, supercapacitors, lithium-ion battery anodes and high-efficiency adsorption materials.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.1~0.5:0.05~0.2. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0012] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0013] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 1~5ºC·min.-1 Heat to 200~300ºC and hold for 1~5 hours to obtain the pre-oxidized fiber membrane.

[0014] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 2~10ºC·min. -1 The carbon-based nanofiber membrane is prepared by heating to 800~1200ºC and holding for 1~5 hours.

[0015] The biomass carbon source is one or two of lignin, cellulose, and chitosan.

[0016] The conductive enhancer is one of carbon nanotubes, graphene, and polyaniline.

[0017] The crosslinking agent is one of glutaraldehyde, epichlorohydrin, and genipin.

[0018] The organic solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, and acetic acid.

[0019] The electrospinning process parameters described in step 2 are as follows: spinning voltage 10~25kV, take-up distance 10~20cm, and liquid push rate 0.5~2mL·h. -1 The spinning temperature is 20~40ºC and the humidity is 30~60RH.

[0020] The tension applied in step 3 is 0.5~1.5N.

[0021] The inert atmosphere described in step 4 is either nitrogen or argon.

[0022] The carbon-based nanofiber membrane is mainly composed of carbon, and contains oxygen and nitrogen; the carbon-based nanofibers have a diameter of 100~500nm and a specific surface area of ​​500~1500m². 2 / g, with an electrical conductivity of 50~200S / cm.

[0023] The carbon-based nanofiber membrane is used in flexible electrodes, supercapacitors, lithium-ion battery anode materials, or gas adsorption and filtration materials.

[0024] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1) This invention achieves greening and cost reduction of the raw material system: Compared with other existing technologies that rely on expensive petrochemical raw materials (such as PAN), it innovatively adopts widely available and inexpensive renewable biomass (such as lignin and cellulose) as the main carbon source, which fundamentally and significantly reduces the cost of raw materials (by more than 60%), completely getting rid of dependence on non-renewable petrochemical resources, and meeting the requirements of green chemistry and sustainable development.

[0025] 2) This invention simplifies the preparation process and significantly reduces energy consumption: Addressing the core bottleneck of high energy consumption and long processing time (several hours) in the pre-oxidation process of existing technologies, this invention optimizes the thermal stability behavior of carbon-based nanofiber membranes through unique component design, significantly shortening the pre-oxidation time and lowering the processing temperature. This results in an overall reduction of energy consumption by approximately 30% to 50%, significantly improving production efficiency. Simultaneously, this invention integrates conductivity enhancement and molecular cross-linking steps into the precursor spinning solution, achieving a "one-step" preparation process. This avoids complex and environmentally polluting secondary composite or post-activation processes, resulting in a simpler and more environmentally friendly process.

[0026] 3) This invention achieves superior performance and a one-step solution: Unlike existing technologies that sacrifice mechanical strength for high specific surface area through strong acid and alkali post-treatment, and unlike aerogel technology which is difficult to prepare continuous films, this invention successfully solves the technical problem of poor performance of biomass carbon fibers through an innovative strategy of in-situ introduction of conductive reinforcing agents and crosslinking agents, achieving a synergistic improvement in comprehensive performance, and simultaneously achieving the following in a single carbonization process: Excellent conductivity: The conductive reinforcing agents (CNTs, graphene) construct a stable three-dimensional interconnected conductive network inside the carbon-based nanofiber membrane. The conductivity (50~200S / cm) is comparable to or even better than some PAN-based carbon fibers, completely overcoming the defect of poor conductivity of traditional biomass carbon fibers.

[0027] High mechanical strength and flexibility: The crosslinking agent significantly enhances the connection between biomass molecular chains, forming a strong and flexible carbon network structure after carbonization. Its tensile strength (15~28MPa) and flexibility are far superior to the inherently brittle PAN-based carbon fibers (such as the product described in CN117646294A), which can meet the requirements of repeated bending of flexible devices.

[0028] High specific surface area: Utilizing the abundant functional groups and controllable pyrolysis behavior of biomass, combined with the template effect of conductive agents, high specific surface area (500~1500m²) can be directly obtained without corrosive post-treatment. 2 It has a porous fiber structure ( / g) and perfectly maintains the mechanical integrity of the fiber network.

[0029] 4) The invention has significant application advantages and broad market prospects: The carbon-based nanofiber membrane prepared integrates excellent conductivity, high specific surface area and good flexibility. It is a high-performance, self-supporting flexible functional material that can be directly used as an electrode in supercapacitors, lithium-ion batteries and other fields without the need for additional current collectors and binders, which simplifies the device manufacturing process. At the same time, it also shows great application potential in fields such as high-efficiency adsorption, catalysis and electromagnetic shielding.

[0030] Therefore, the process of this invention is simple, low-cost, environmentally friendly, and suitable for large-scale production; the carbon-based nanofiber membrane prepared has the characteristics of high conductivity, high specific surface area and excellent mechanical properties, and can be widely used in flexible electronics, supercapacitors, lithium-ion batteries and high-efficiency adsorption materials. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but this is not intended to limit the scope of protection of the present invention.

[0032] A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.1~0.5:0.05~0.2. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0033] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0034] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 1~5ºC·min. -1 Heat to 200~300ºC and hold for 1~5 hours to obtain the pre-oxidized fiber membrane.

[0035] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 2~10ºC·min. -1 The carbon-based nanofiber membrane is prepared by heating to 800~1200ºC and holding for 1~5 hours.

[0036] The biomass carbon source is one or two of lignin, cellulose, and chitosan.

[0037] The conductive enhancer is one of carbon nanotubes, graphene, and polyaniline.

[0038] The crosslinking agent is one of glutaraldehyde, epichlorohydrin, and genipin.

[0039] The organic solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, and acetic acid.

[0040] The electrospinning process parameters described in step 2 are as follows: spinning voltage 10~25kV, take-up distance 10~20cm, and liquid push rate 0.5~2mL·h. -1 The spinning temperature is 20~40ºC and the humidity is 30~60RH.

[0041] The tension applied in step 3 is 0.5~1.5N.

[0042] The inert atmosphere described in step 4 is either nitrogen or argon.

[0043] The carbon-based nanofibers have a diameter of 100-500 nm and a specific surface area of ​​500-1500 m². 2 / g, with an electrical conductivity of 50~200S / cm.

[0044] The carbon-based nanofiber membrane is used in flexible electrodes, supercapacitors, lithium-ion battery anodes, or gas adsorption and filtration materials.

[0045] In this specific implementation: The carbon-based nanofiber membrane is mainly composed of carbon and contains oxygen and nitrogen.

[0046] The examples will not be repeated here. Example 1 A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.1:0.05. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0047] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0048] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 1ºC·min -1 The temperature was raised to 275ºC and held for 4 hours to obtain the pre-oxidized fiber membrane.

[0049] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 4ºC·min. -1 The temperature was raised to 800ºC and held for 1 hour to obtain a carbon-based nanofiber membrane.

[0050] The biomass carbon source is lignin.

[0051] The conductivity enhancer is carbon nanotubes.

[0052] The crosslinking agent is glutaraldehyde.

[0053] The organic solvent is N,N-dimethylformamide.

[0054] The electrospinning process parameters described in step 2 are as follows: spinning voltage is 20kV, take-up distance is 15cm, and liquid push rate is 1mL·h. -1 The spinning temperature was 25ºC and the humidity was 50RH.

[0055] The tension applied in step 3 is 0.5 N.

[0056] The inert atmosphere described in step 4 is nitrogen.

[0057] The carbon-based nanofibers prepared in this embodiment have a uniform diameter, averaging 220 nm, and a rough surface, indicating CNT embedding and the formation of a microporous structure. The carbon-based nanofiber membrane was tested and found to have a specific surface area of ​​1250 m². 2 ·g -1 The conductivity is 150 S·cm -1 The tensile strength is 15 MPa.

[0058] The prepared carbon-based nanofiber membrane was directly used as a self-supporting electrode for supercapacitor testing at 1 A·g. -1 At current density, the specific capacitance reaches 210 F·g -1 It exhibits excellent electrochemical performance.

[0059] Example 2 A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.12:0.1. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0060] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0061] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 3ºC·min -1 The temperature was raised to 300ºC and held for 1 hour to obtain the pre-oxidized fiber membrane.

[0062] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 10ºC·min. -1 The carbon-based nanofiber membrane was obtained by heating to 1100ºC and holding for 5 hours.

[0063] The biomass carbon source is chitosan.

[0064] The conductivity enhancer is graphene.

[0065] The crosslinking agent is genipin.

[0066] The organic solvent is N-methylpyrrolidone.

[0067] The electrospinning process parameters described in step 2 are as follows: spinning voltage is 10kV, take-up distance is 10cm, and liquid push rate is 2mL·h. -1 The spinning temperature was 40ºC and the humidity was 60RH.

[0068] The tension applied in step 3 is 1.5 N.

[0069] The inert atmosphere described in step 4 is argon.

[0070] The carbon-based nanofiber membrane prepared in this embodiment maintained a good three-dimensional network structure with an average fiber diameter of approximately 180 nm. Due to the use of chitosan as the carbon source and genipin as the crosslinking agent, nitrogen was successfully introduced; XPS analysis showed a nitrogen atom content of 5.2 at%. The carbon-based nanofiber membrane was tested and found to have a specific surface area of ​​980 m². 2 ·g -1 The conductivity is 85 S·cm -1 .

[0071] The carbon-based nanofiber membrane prepared in this embodiment exhibits good hydrophilicity, and its adsorption capacity for CO2 gas reaches 2.8 mmol·g at 25ºC and 1 bar. -1 It is suitable for use in the field of gas adsorption and filtration materials.

[0072] Example 3 A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.3:0.15. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0073] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0074] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 4ºC·min -1 The temperature was raised to 200ºC and held for 5 hours to obtain the pre-oxidized fiber membrane.

[0075] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 8ºC·min. -1 The carbon-based nanofiber membrane was prepared by heating to 1200ºC and holding for 4 hours.

[0076] The biomass carbon source is cellulose.

[0077] The conductivity enhancer is polyaniline.

[0078] The crosslinking agent is epichlorohydrin.

[0079] The organic solvent is acetic acid.

[0080] The electrospinning process parameters described in step 2 are as follows: spinning voltage is 25kV, take-up distance is 20cm, and liquid push rate is 0.5mL·h. -1 The spinning temperature was 20ºC and the humidity was 30RH.

[0081] The tension applied in step 3 is 1N.

[0082] The inert atmosphere described in step 4 is nitrogen.

[0083] The carbon-based nanofiber membrane prepared in this embodiment has a relatively large diameter, averaging 450 nm, but the fibers are well-fused, forming a very robust network structure. The carbon-based nanofiber membrane was tested and found to have a tensile strength of 25 MPa, an elongation at break of 8%, and a specific surface area of ​​1500 m². 2 ·g -1 The conductivity is 50 S·cm -1 .

[0084] The carbon-based nanofiber membrane prepared in this embodiment has good flexibility and can be directly used as a self-supporting flexible electrode carrier. After loading silicon nanoparticles, it exhibits excellent cycle stability.

[0085] Example 4 A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.4:0.2. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0086] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0087] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 5ºC·min -1 The temperature was raised to 250ºC and held for 3 hours to obtain the pre-oxidized fiber membrane.

[0088] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 6ºC·min. -1 The temperature was raised to 1000ºC and held for 2 hours to obtain a carbon-based nanofiber membrane.

[0089] The biomass carbon source is a mixture of lignin and chitosan.

[0090] The conductivity enhancer is graphene.

[0091] The crosslinking agent is epichlorohydrin.

[0092] The organic solvent is N,N-dimethylformamide.

[0093] The electrospinning process parameters described in step 2 are as follows: spinning voltage is 15kV, take-up distance is 18cm, and liquid push rate is 1.5mL·h. -1 The spinning temperature was 30ºC and the humidity was 40RH.

[0094] The tension applied in step 3 is 0.8 N.

[0095] The inert atmosphere described in step 4 is argon.

[0096] In this embodiment, high-temperature treatment significantly improved the graphitization degree of the carbon-based nanofiber membrane. The resulting carbon-based nanofiber membrane had a diameter of 500 nm and a significantly improved electrical conductivity, reaching 200 S·cm. -1 However, the specific surface area decreased to 500 m² due to high-temperature sintering. 2 ·g -1 .

[0097] The prepared carbon-based nanofiber membranes are well-suited for applications requiring extremely high conductivity, such as lithium-ion battery anodes and supercapacitors.

[0098] Example 5 A carbon-based nanofiber membrane, its preparation method, and its application. The preparation method and application described in this specific embodiment are as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.5:0.15. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution.

[0099] Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane.

[0100] Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 1ºC·min -1 The temperature was raised to 225ºC and held for 2 hours to obtain the pre-oxidized fiber membrane.

[0101] Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 2ºC·min. -1 The temperature was raised to 900ºC and held for 3 hours to obtain a carbon-based nanofiber membrane.

[0102] The biomass carbon source is a mixture of lignin and cellulose.

[0103] The conductivity enhancer is carbon nanotubes.

[0104] The crosslinking agent is genipin.

[0105] The organic solvent is N-methylpyrrolidone.

[0106] The electrospinning process parameters described in step 2 are as follows: spinning voltage is 20kV, take-up distance is 13cm, and liquid push rate is 1mL·h. -1 The spinning temperature was 35ºC and the humidity was 30RH.

[0107] The tension applied in step 3 is 1.3 N.

[0108] The inert atmosphere described in step 4 is nitrogen.

[0109] The biomass carbon source blending and process optimization used in this embodiment enable the prepared carbon-based nanofiber membrane to maintain good electrical conductivity (110 S·cm). -1 ) and specific surface area (850mm²) 2 ·g -1 At the same time, the carbon-based nanofiber membrane has an average diameter of about 100nm, achieves optimal mechanical properties, increases tensile strength to 28MPa, and has good flexibility, allowing it to be repeatedly bent without breaking.

[0110] The carbon-based nanofiber membrane prepared in this embodiment has broad application prospects in flexible electrodes.

[0111] This specific implementation method has the following advantages compared with the prior art: 1) This specific implementation method achieves greening and low cost of raw material system: Compared with other existing technologies that rely on expensive petrochemical raw materials (such as PAN), it innovatively adopts widely available and inexpensive renewable biomass (such as lignin and cellulose) as the main carbon source, which fundamentally and significantly reduces the cost of raw materials (by more than 60%), completely gets rid of dependence on non-renewable petrochemical resources, and meets the requirements of green chemistry and sustainable development.

[0112] 2) This specific embodiment simplifies the preparation process and significantly reduces energy consumption: Addressing the core bottleneck of high energy consumption and long processing time (several hours) in the pre-oxidation process of existing technologies, this specific embodiment optimizes the thermal stability behavior of the carbon-based nanofiber membrane through unique component design, significantly shortening the pre-oxidation time and lowering the processing temperature. This results in an overall reduction of energy consumption by approximately 30% to 50%, significantly improving production efficiency. Simultaneously, this specific embodiment integrates conductivity enhancement and molecular cross-linking steps into the precursor spinning solution, achieving a "one-step" preparation method. This avoids complex and environmentally polluting secondary composite or post-activation processes, resulting in a simpler and more environmentally friendly process.

[0113] 3) This specific embodiment achieves superior performance and a one-step solution: Unlike existing technologies that sacrifice mechanical strength for high specific surface area through strong acid and alkali post-treatment, and unlike aerogel technology which is difficult to prepare continuous films, this specific embodiment successfully solves the technical problem of poor performance of biomass carbon fibers by introducing conductive reinforcing agents and crosslinking agents in situ, achieving a synergistic improvement in overall performance, and simultaneously achieving the following in a single carbonization process: Excellent conductivity: The conductive reinforcing agents (CNTs, graphene) construct a stable three-dimensional interconnected conductive network inside the carbon-based nanofiber membrane. The conductivity (50~200S / cm) is comparable to or even better than some PAN-based carbon fibers, completely overcoming the defect of poor conductivity of traditional biomass carbon fibers.

[0114] High mechanical strength and flexibility: The crosslinking agent significantly enhances the connection between biomass molecular chains, forming a strong and flexible carbon network structure after carbonization. Its tensile strength (15~28MPa) and flexibility are far superior to the inherently brittle PAN-based carbon fibers (such as the product described in CN117646294A), which can meet the requirements of repeated bending of flexible devices.

[0115] High specific surface area: Utilizing the abundant functional groups and controllable pyrolysis behavior of biomass, combined with the template effect of conductive agents, high specific surface area (500~1500m²) can be directly obtained without corrosive post-treatment. 2 It has a porous fiber structure ( / g) and perfectly maintains the mechanical integrity of the fiber network.

[0116] 4) This specific implementation method has significant application advantages and broad market prospects: The carbon-based nanofiber membrane prepared integrates excellent conductivity, high specific surface area and good flexibility. It is a high-performance, self-supporting flexible functional material that can be directly used as an electrode in supercapacitors, lithium-ion batteries and other fields without the need for additional current collectors and binders, which simplifies the device manufacturing process. At the same time, it also shows great application potential in fields such as high-efficiency adsorption, catalysis and electromagnetic shielding.

[0117] Therefore, this specific embodiment has a simple process, low cost, environmental friendliness, and is suitable for large-scale production; the prepared carbon-based nanofiber membrane has the characteristics of high conductivity, high specific surface area and excellent mechanical properties, and is widely used in flexible electronics, supercapacitors, lithium-ion batteries and high-efficiency adsorption materials.

Claims

1. A method for preparing a carbon-based nanofiber membrane, characterized in that, The preparation method is as follows: Step 1: Prepare the materials according to the mass ratio of biomass carbon source: conductive enhancer: crosslinking agent of 1:0.1~0.5:0.05~0.

2. Dissolve the biomass carbon source, the conductive enhancer and the crosslinking agent in an organic solvent and stir evenly to obtain a spinning solution. Step 2: Electrospin the spinning solution to obtain a precursor fiber membrane; Step 3: In an air atmosphere, first apply tension to the precursor fiber membrane, then perform a pre-oxidation treatment: at 1~5ºC·min. -1 Heat to 200~300ºC and hold for 1~5 hours to obtain the pre-oxidized fiber membrane; Step 4: Carbonize the pre-oxidized fiber membrane in an inert atmosphere at 2~10ºC·min. -1 The carbon-based nanofiber membrane is prepared by heating to 800~1200ºC and holding for 1~5 hours.

2. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The biomass carbon source is one or two of lignin, cellulose, and chitosan.

3. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The conductive enhancer is one of carbon nanotubes, graphene, and polyaniline.

4. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The crosslinking agent is one of glutaraldehyde, epichlorohydrin, and genipin.

5. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The organic solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, and acetic acid.

6. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The electrospinning process parameters described in step 2 are as follows: spinning voltage 10~25kV, take-up distance 10~20cm, and liquid push rate 0.5~2mL·h. -1 The spinning temperature is 20~40ºC and the humidity is 30~60RH.

7. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The tension applied in step 3 is 0.5~1.5N.

8. The method for preparing carbon-based nanofiber membranes according to claim 1, characterized in that, The inert atmosphere described in step 4 is either nitrogen or argon.

9. A carbon-based nanofiber membrane, characterized in that, The carbon-based nanofiber membrane is a carbon-based nanofiber membrane prepared by the method for preparing carbon-based nanofiber membrane according to any one of claims 1 to 8; The carbon-based nanofiber membrane is mainly composed of carbon, and contains oxygen and nitrogen; the carbon-based nanofibers have a diameter of 100~500nm and a specific surface area of ​​500~1500m². 2 / g, with an electrical conductivity of 50~200S / cm.

10. An application of the carbon-based nanofiber membrane as described in claim 9, characterized in that, Carbon-based nanofiber membranes are used in flexible electrodes, supercapacitors, lithium-ion battery anodes, or gas adsorption and filtration materials.