A porous carbon nanofiber and a preparation method and application thereof

Abstract

The application discloses a kind of porous carbon nanofibers and preparation method thereof, belong to porous carbon preparation technical field, its preparation method includes the following steps: with PAN and PMMA as raw material, DMF is solvent, and core-shell solution is prepared;With PMMA as raw material, DMF is solvent, and inner core solution is prepared;Using coaxial spinning technology, voltage is applied to needle, and spinning operation is carried out, and precursor is prepared;In air atmosphere, precursor is heated to 250-300 DEG C, and keeps warm for 100-150 min;In nitrogen protective atmosphere, the treated precursor is heated to 750-850 DEG C, and keeps warm for 50-70 min, and is cooled to room temperature, and porous carbon nanofiber is prepared.The method process is simple, easy to operate, and the prepared porous carbon nanofiber has good performance.

Description

Technical Field

[0001] This invention belongs to the field of porous carbon preparation technology, specifically relating to a porous carbon nanofiber, its preparation method, and its application. Background Technology

[0002] Lithium-ion capacitors (LICs) possess the high energy density and high power density characteristics of lithium-ion batteries and supercapacitors. However, the mismatch between capacitive cathodes and battery-type anodes in terms of charge storage capacity and electrode kinetics remains a significant issue. Achieving high power density while maintaining high energy density remains a challenge for current LICs. Therefore, further exploration of suitable positive and negative electrode materials is necessary. Currently, promising negative electrodes for LICs typically include carbon materials, metal oxides, conductive polymers, metal-organic frameworks (MOFs), transition metal carbides / nitrides (MXenes), and their composites. Among these, carbon materials have attracted continuous attention from researchers due to their abundant sources, low cost, environmental friendliness, large specific surface area (SSA), tunable pore structure, high conductivity, and stable physicochemical properties. Carbon materials, including carbon nanofibers, graphene, and carbon aerogels, have been explored as negative electrode materials.

[0003] Carbon nanofibers (CNFs) are high-performance fibers that possess advantages such as low density, high modulus, conductivity, excellent chemical stability, and processability. They also exhibit fewer defects, a high aspect ratio, a large specific surface area, and a dense structure. These properties make them highly advantageous in promoting chemical reactions. However, as electrode materials, the main limitations of pure CNFs include low specific capacity, insufficient cycle stability, limited ion transport, and high interfacial resistance. These factors collectively lead to capacity degradation and poor long-term performance. To address these issues, structural modification of CNFs has become an effective strategy. This modification can adjust the electronic structure, increase surface defects and active sites, and enhance electrolyte ion adsorption and redox reactions, thereby improving specific capacity.

[0004] Existing improvement methods include atomic doping, composite structure design, and pore engineering. However, most existing preparation methods suffer from drawbacks such as complex operation, high cost, and poor material properties. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, this invention provides a porous carbon nanofiber and its preparation method. This method is simple, easy to operate, and produces porous carbon nanofibers with excellent performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: A method for preparing porous carbon nanofibers includes the following steps: (1) Prepare a core-shell solution using PAN and PMMA as raw materials and DMF as solvent; (2) Prepare the core solution using PMMA as raw material and DMF as solvent; (3) Using coaxial spinning technology, voltage is applied to the needle to perform spinning operation and obtain the precursor; (4) In an air atmosphere, heat the precursor to 250-300℃ and keep it at that temperature for 100-150 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 750-850℃, kept at that temperature for 50-70 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0007] Furthermore, in step (1), the molecular weight of PAN is 50,000 to 100,000.

[0008] Further, in step (1), the mass fraction of PAN in the core-shell solution is 8-12%, and the mass ratio of PAN to PMMA is 1:0.2-1.5.

[0009] Furthermore, in step (2), the mass fraction of PMMA in the core solution is 22-26%.

[0010] Furthermore, in step (3), the voltage is 15-20kV and the distance between the needle and the receiver is 15-20cm.

[0011] Furthermore, during the spinning process in step (3), the core-shell solution flow rate is 25-35 μL / min. -1 The core solution flow rate is 8-12 μL / min. -1 .

[0012] Furthermore, the heating rate in step (4) is 1-3℃ / min.

[0013] A porous carbon nanofiber was prepared using the method described above.

[0014] The above-mentioned porous carbon nanofibers are used in the preparation of lithium-ion capacitor anode materials.

[0015] The beneficial effects of this invention are as follows: In this invention, PMMA is introduced into the PAN core-shell solution as a pore-forming agent to obtain a one-dimensional porous carbon structure. These porous carbon structures are stacked to form a three-dimensional network structure, providing good conductivity. The PMMA solution serves as the core, providing a hollow structure and abundant active sites for ions. When the resulting material is made into a negative electrode of a lithium-ion capacitor, it exhibits good electrochemical performance.

[0016] The method in this invention is simple to operate, does not require complex equipment, and is easy to use in industrial applications. Attached Figure Description

[0017] Figure 1 This is a process flow diagram for porous carbon fiber. Figure 2 Here is a SEM image of the porous carbon nanofibers in Example 1; Figure 3 Here is a SEM image of the porous carbon nanofibers in Example 2; Figure 4 Here is a SEM image of the porous carbon nanofibers in Example 3; Figure 5 This is a TEM image of the porous carbon nanofibers in Example 2; Figure 6 The diagram shows the cycling performance of the porous carbon nanofibers in Examples 1-3. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0019] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0021] The features and performance of the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0022] Example 1 A porous carbon nanofiber is prepared by means of the following steps: (1) A core-shell solution was prepared using PAN (molecular weight 100,000) and PMMA as raw materials and DMF as solvent, wherein the mass fraction of PAN was 10% and the mass ratio of PAN to PMMA was 1:0.2; (2) A core solution was prepared using PMMA as the raw material and DMF as the solvent, wherein the mass fraction of PMMA was 24%; (3) Coaxial spinning technology was used, with the distance between the needle and the receiver being 18 cm. A voltage of 18 kV was applied to the needle for spinning. During the spinning process, the core-shell solution flow rate was 30 μL / min. -1 The core solution flow rate was 10 μL / min. -1 The precursor was obtained; (4) In an air atmosphere, the precursor is heated to 280°C at a rate of 2°C / min and held for 120 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 800°C, kept at that temperature for 60 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0023] Example 2 A porous carbon nanofiber is prepared by means of the following steps: (1) A core-shell solution was prepared using PAN (molecular weight 100,000) and PMMA as raw materials and DMF as solvent, wherein the mass fraction of PAN was 10% and the mass ratio of PAN to PMMA was 1:0.5; (2) A core solution was prepared using PMMA as the raw material and DMF as the solvent, wherein the mass fraction of PMMA was 24%; (3) Coaxial spinning technology was used, with the distance between the needle and the receiver being 18 cm. A voltage of 18 kV was applied to the needle for spinning. During the spinning process, the core-shell solution flow rate was 30 μL / min. -1 The core solution flow rate was 10 μL / min. -1 The precursor was obtained; (4) In an air atmosphere, the precursor is heated to 280°C at a rate of 2°C / min and held for 120 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 800°C, kept at that temperature for 60 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0024] Example 3 A porous carbon nanofiber is prepared by means of the following steps: (1) A core-shell solution was prepared using PAN (molecular weight 100,000) and PMMA as raw materials and DMF as solvent, wherein the mass fraction of PAN was 10% and the mass ratio of PAN to PMMA was 1:1.5; (2) A core solution was prepared using PMMA as the raw material and DMF as the solvent, wherein the mass fraction of PMMA was 24%; (3) Coaxial spinning technology was used, with the distance between the needle and the receiver being 18 cm. A voltage of 18 kV was applied to the needle for spinning. During the spinning process, the core-shell solution flow rate was 30 μL / min. -1 The core solution flow rate was 10 μL / min. -1 The precursor was obtained; (4) In an air atmosphere, the precursor is heated to 280°C at a rate of 2°C / min and held for 120 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 800°C, kept at that temperature for 60 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0025] Example 4 A porous carbon nanofiber is prepared by means of the following steps: (1) A core-shell solution was prepared using PAN (molecular weight 50,000) and PMMA as raw materials and DMF as solvent, wherein the mass fraction of PAN was 8% and the mass ratio of PAN to PMMA was 1:1. (2) A core solution was prepared using PMMA as the raw material and DMF as the solvent, wherein the mass fraction of PMMA was 22%; (3) Coaxial spinning technology was used, with the needle distance from the receiver being 15cm. A voltage of 15kV was applied to the needle for spinning. During the spinning process, the core-shell solution flow rate was 25μL / min. -1 The core solution flow rate was 8 μL / min. -1 The precursor was obtained; (4) In an air atmosphere, the precursor is heated to 250°C at a rate of 1°C / min and held for 150 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 750°C, kept at that temperature for 70 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0026] Example 5 A porous carbon nanofiber is prepared by means of the following steps: (1) A core-shell solution was prepared using PAN (molecular weight 80,000) and PMMA as raw materials and DMF as solvent, wherein the mass fraction of PAN was 12% and the mass ratio of PAN to PMMA was 1:1. (2) A core solution was prepared using PMMA as the raw material and DMF as the solvent, wherein the mass fraction of PMMA was 26%; (3) Coaxial spinning technology was used, with the needle distance from the receiver being 20 cm. A voltage of 20 kV was applied to the needle for spinning. During the spinning process, the core-shell solution flow rate was 35 μL / min. -1 The core solution flow rate was 12 μL / min. -1 The precursor was obtained; (4) In an air atmosphere, the precursor is heated to 300°C at a rate of 3°C / min and held for 100 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 850°C, kept at that temperature for 50 min, and then cooled to room temperature to obtain porous carbon nanofibers.

[0027] Test case Taking the materials in Examples 1-3 as examples, the porous carbon nanofibers prepared in Examples 1-3 were observed and tested respectively, as detailed in the following figures. Figure 2-6 .

[0028] Figure 1 This is a process flow diagram for the porous carbon nanofibers; Figure 2 Here is a SEM image of the porous carbon nanofibers in Example 1; Figure 3 Here is a SEM image of the porous carbon nanofibers in Example 2; Figure 4 This is a SEM image of the porous carbon nanofibers in Example 3; through... Figure 2-4 It can be seen that after adding PMMA pore-forming agent, pores and hollow tubular structures appear on the fiber surface, and the pore structure on the fiber surface gradually increases with the increase of PMMA amount.

[0029] Figure 5 The image shown is a TEM image of the porous carbon nanofibers in Example 2. It can be seen that the pores and hollow structures on the fiber surface can be clearly observed. The pore size on the fiber surface is roughly between 20-60 nm, which belongs to macropores and mesopores.

[0030] Figure 6 The graphs show the cycling performance of lithium-ion half-cells assembled from porous carbon nanofibers in Examples 1-3. It can be seen that at 1 Ag... -1 At the given current density, the specific capacity of the materials in Examples 1-3 was 160.35 mAh g, respectively. -1 193.35mAhg -1 180.3mAhg -1 .

Claims

1. A method for preparing porous carbon nanofibers, characterized in that, Includes the following steps: (1) Prepare a core-shell solution using PAN and PMMA as raw materials and DMF as solvent; (2) Prepare the core solution using PMMA as raw material and DMF as solvent; (3) Using coaxial spinning technology, voltage is applied to the needle to perform spinning operation and obtain the precursor; (4) In an air atmosphere, heat the precursor to 250-300℃ and keep it at that temperature for 100-150 min; (5) In a nitrogen protective atmosphere, the treated precursor is heated to 750-850℃, kept at that temperature for 50-70 min, and then cooled to room temperature to obtain porous carbon nanofibers.

2. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, In step (1), the molecular weight of PAN is 50,000 to 100,000.

3. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, In step (1), the mass fraction of PAN in the core-shell solution is 8-12%, and the mass ratio of PAN to PMMA is 1:0.2-1.

5.

4. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, In step (2), the mass fraction of PMMA in the core solution is 22-26%.

5. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, In step (3), the voltage is 15-20kV and the distance between the needle and the receiver is 15-20cm.

6. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, In step (3), during the spinning process, the core-shell solution flow rate is 25-35 μL / min. -1 The core solution flow rate is 8-12 μL / min. -1 .

7. The method for preparing porous carbon nanofibers as described in claim 1, characterized in that, The heating rate in step (4) is 1-3℃ / min.

8. A porous carbon nanofiber, characterized in that, It is prepared by any one of claims 1-7.

9. The application of the porous carbon nanofibers according to claim 7 in the preparation of lithium-ion capacitor anode materials.

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