A flexible carbon nanotube-based composite electrode material film and a preparation method thereof

Abstract

This invention belongs to the field of nanomaterials and energy material preparation technology, and discloses a flexible carbon nanotube-based composite electrode material film and its preparation method. This method combines the high-temperature heat source provided by combustion with the inductive effect of an applied vertical DC magnetic field to achieve the directional growth and in-situ continuous film formation of carbon nanotubes in a low-pressure, closed environment. By transporting catalyst particles to the combustion reaction zone, the diffusion flame formed by methane and oxygen provides the carbon source and heat energy for carbon nanotube growth. Simultaneously, a magnetic field is applied to guide the carbon nanotubes to align in a specific direction and deposit them on a stainless steel mesh, forming a dense and flexible composite film. The resulting film exhibits excellent flexibility, good conductivity, and mechanical stability. This method is simple, requires low equipment investment, avoids the complexity of traditional high-temperature CVD processes and subsequent transfer processing, and achieves efficient and controllable preparation of flexible carbon nanotube composite electrode materials, showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and energy materials preparation technology, specifically relating to a flexible carbon nanotube-based composite electrode material thin film and its preparation method. Background Technology

[0002] With the rapid development of flexible electronics technology, the demand for high-performance flexible electrode materials is becoming increasingly urgent. Carbon nanotubes, due to their excellent conductivity, mechanical properties, and chemical stability, have become ideal candidate materials for flexible electrodes. However, existing methods for preparing carbon nanotube films have many shortcomings: chemical vapor deposition (CVD) involves complex equipment and high costs; solution filtration requires cumbersome post-processing and results in low film strength; and direct growth methods struggle to achieve oriented alignment of carbon nanotubes, thus limiting the material's performance.

[0003] Magnetic field-assisted synthesis (MLS) can induce the directional growth of nanomaterials through magnetic dipole interactions, significantly improving the anisotropic properties of the materials. A low-pressure environment helps reduce impurity interference, improving catalyst activity and product purity. Combustion, as a highly efficient heat source technology, has the advantages of fast reaction speed and low energy consumption; however, carbon nanotubes prepared by traditional combustion methods suffer from severe agglomeration and poor orientation.

[0004] Therefore, developing a preparation technique that combines the advantages of low-pressure environment, magnetic field induction and combustion method to achieve in-situ synthesis of flexible thin films with oriented carbon nanotubes is of great significance for promoting the development of flexible electrode materials. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a flexible carbon nanotube-based composite electrode material thin film and its preparation method, so as to solve the problems pointed out in the background art.

[0006] To achieve the aforementioned objectives, the technical solution adopted is as follows:

[0007] A method for preparing a flexible carbon nanotube-based composite electrode material thin film includes the following steps:

[0008] 1) The metal salt catalyst is refined to obtain metal salt catalyst particles, which are then loaded into a catalyst container;

[0009] 2) The vacuum is drawn to a low pressure environment of 50-70 kPa in the closed reaction chamber, and methane and oxygen are introduced to form a stable diffusion-type combustion flame, which provides a high-temperature heat source and carbon source for the growth of carbon nanotubes.

[0010] 3) Inert gas is used to transport metal salt catalyst particles to the combustion reaction zone of the combustion flame;

[0011] 4) An electromagnetic device with a vertical DC magnetic field is set above the combustion zone. A magnetic field with a strength of 2000-5000 Gs is applied synchronously during the growth of carbon nanotubes by the electromagnetic device. The magnetic force guides the carbon nanotubes to align along the direction of the magnetic field and deposits and cross-links them into a flexible and dense carbon nanotube-based composite electrode material film.

[0012] 5) The carbon nanotube-based composite electrode material film is deposited on a stainless steel mesh carrier and crosslinked in situ to form a continuous film.

[0013] As a further improvement of the present invention, the metal salt catalyst is at least one selected from ferrous sulfate, ferric sulfate, cobalt sulfate and nickel sulfate.

[0014] As a further improvement of the present invention, in step 1), the particle size of the metal salt catalyst particles is controlled to be 100-1000 nm.

[0015] As a further improvement of the present invention, the volumetric flow rate ratio of methane to oxygen is 2:1, and the total flow rate ranges from 1000 to 3000 mL / min.

[0016] As a further improvement of the present invention, the inert gas is argon, and the flow rate ranges from 50 to 500 mL / min.

[0017] As a further improvement of the present invention, the distance between the electromagnetic device and the tip of the combustion flame is 80 mm.

[0018] A flexible carbon nanotube-based composite electrode material film is composed of oriented carbon nanotubes and metal salt catalyst particles. The carbon nanotubes are oriented and cross-linked in a vertical direction to form a dense and continuous flexible network structure, and the metal salt catalyst particles are uniformly distributed on the carbon nanotube walls.

[0019] Application of a flexible carbon nanotube-based composite electrode material film in flexible supercapacitors and wearable electronic devices.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention overcomes the problems of random growth direction and severe agglomeration of carbon nanotubes in traditional combustion methods by applying a vertical DC magnetic field above the combustion zone to guide the carbon nanotubes to align along the magnetic field direction during growth. The magnetic field-assisted effect enables the carbon nanotubes to achieve synchronous directional alignment and cross-linking during deposition, thereby achieving in-situ continuous film formation during the reaction process without the need for additional pressing or bonding treatment, significantly improving the integrity and uniformity of the film structure.

[0022] 2. The obtained flexible carbon nanotube-based composite electrode material film exhibits excellent flexibility, maintaining structural stability under mechanical deformations such as bending and twisting. It also possesses good conductivity, making it suitable for use in flexible electronic devices and portable energy storage devices. Under the influence of a magnetic field, the carbon nanotubes tightly align to form a continuous conductive network, effectively reducing the film's sheet resistance and enhancing its overall current-carrying capacity and electrochemically active interface.

[0023] 3. The entire preparation process is completed in a low-pressure combustion system, combined with a magnetic field induction mechanism, without relying on expensive high-vacuum CVD equipment or complex post-processing steps. All operating parameters (such as atmosphere pressure, magnetic field strength, catalyst type, carbon source ratio, etc.) are adjustable, providing good controllability and repeatability, facilitating rapid optimization and process iteration under different functional requirements.

[0024] 4. Vacuum or low-pressure environments help improve the spatial uniformity of catalyst particles, reduce the risk of agglomeration, and promote the uniform nucleation and growth of carbon nanotubes. Combined with magnetic field induction, this not only improves the morphological uniformity of carbon nanotubes but also inhibits impurity deposition and carbon shell coating, thereby increasing the purity and structural order of carbon nanotubes and enhancing their actual performance in electrode materials.

[0025] 5. Compared to traditional chemical vapor deposition (CVD) or vacuum filtration methods, the process route provided by this invention is simpler and more scalable, requires lower equipment investment, and is easier to implement in a continuous and modular design. It has significant advantages, especially in the continuous manufacturing of large-size flexible electrodes, and is expected to promote the large-scale application of carbon-based flexible electrode materials in wearable electronics, energy storage, and other fields. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a TEM image of the carbon nanotube-based composite film prepared in Example 1;

[0028] Figure 2 This is a TEM image of the carbon nanotube-based composite film prepared in Example 2;

[0029] Figure 3 The charge-discharge curves of the carbon nanotube-based composite film prepared in Example 2 are shown. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0031] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] Example 1

[0036] A method for preparing a flexible carbon nanotube-based composite electrode material thin film includes the following steps:

[0037] 1) 2.0g of ferrous sulfate powder was ball-milled to a particle size of approximately 200nm and then loaded into a catalyst container;

[0038] 2) In a low-pressure chamber at 60 kPa, a mixture of methane and oxygen (volume flow ratio 2:1) is introduced at a total flow rate of 2000 mL / min to ignite and form a stable flame. Argon gas is then introduced at a flow rate of 100 mL / min to transport the catalyst particles to the center of the combustion flame.

[0039] 3) The electromagnetic device is activated to apply a vertical DC magnetic field of 2500 Gs. Carbon nanotubes are rapidly generated under the action of the catalyst, and under the induction of the magnetic field, they grow and cross-link in a vertical direction, depositing on the surface of the stainless steel mesh below to form a continuous, dense, flexible film.

[0040] Figure 1 This is a TEM image of the flexible carbon nanotube-based composite film prepared in step 3) of this embodiment. Figure 1 As can be seen from the figure, a large number of uniformly distributed metal nanoparticles, mainly concentrated in the 5-10 nm range, are attached to the carbon nanotube walls. These particles are Fe-based catalytic active centers generated in situ during flame reduction, effectively inducing the epitaxial growth of carbon nanotubes. Simultaneously, the carbon nanotubes exhibit a distinct hollow tubular structure with a diameter of approximately 10-20 nm, dense walls, and a complete structure; no obvious graphite layer fracture or aggregation was observed. Furthermore, in some areas, a network-like cross-linked structure forms between the carbon nanotubes, which helps improve the mechanical stability and electronic conduction pathway of the film, making it suitable for constructing flexible energy storage electrodes.

[0041] Example 2

[0042] A method for preparing a flexible carbon nanotube-based composite electrode material thin film includes the following steps:

[0043] 1) Mix ferrous sulfate and cobalt sulfate at a mass ratio of 1:1 until homogeneous, then grind to submicron particles. Take 1.5g of the mixed powder and load it into the catalyst container.

[0044] 2) In a low-pressure chamber at 65 kPa, a mixture of methane and oxygen (volume flow ratio 2:1) is introduced at a total flow rate of 2500 mL / min to ignite and form a stable flame. Argon gas is then introduced at a flow rate of 200 mL / min to transport the catalyst particles to the center of the combustion flame.

[0045] 3) Activate the electromagnetic device to apply a vertical DC magnetic field of 3000 Gs. Carbon nanotubes are rapidly generated under the action of the catalyst, and under the induction of the magnetic field, they grow and cross-link in a vertical direction, depositing on the surface of the stainless steel mesh below to form a continuous, dense, flexible film.

[0046] Figure 2 The TEM image shows the pure carbon nanotubes prepared in step 3) of this embodiment. It clearly displays a large number of uniformly distributed carbon nanotube networks with highly consistent orientation, and their surfaces are uniformly loaded with a large number of nanoparticles. These carbon nanotubes not only provide excellent electron transport channels but also significantly enhance the overall flexibility and mechanical stability of the film material. The particulate matter is tightly attached to the carbon nanotube surface, effectively increasing the specific surface area and the number of reactive sites, which is beneficial for pseudocapacitive reactions. Figure 3The charge-discharge curves of this composite film material, used directly as an electrode material in a supercapacitor, are shown at different current densities. The curves exhibit good symmetry, indicating that the material possesses good reversibility and rapid ion response capability. It also displays a specific capacitance of 190 F / g at a current density of 0.5 A / g.

[0047] Example 3

[0048] A method for preparing a flexible carbon nanotube-based composite electrode material thin film includes the following steps:

[0049] 1) 2.0g of nickel sulfate powder was ball-milled to a particle size of approximately 500nm and then loaded into a catalyst container;

[0050] 2) In a low-pressure chamber at 70 kPa, a mixture of methane and oxygen (volume flow ratio 2:1) is introduced at a total flow rate of 3000 mL / min to ignite and form a stable flame. Argon gas is then introduced at a flow rate of 500 mL / min to transport the catalyst particles to the center of the combustion flame.

[0051] 3) Activate the electromagnetic device to apply a vertical DC magnetic field of 5000 Gs. Carbon nanotubes are rapidly generated under the action of the catalyst and, under the induction of the magnetic field, grow and cross-link in a vertical direction, depositing on the surface of the stainless steel mesh below to form a continuous, dense, flexible film.

[0052] In step 3) of this embodiment, the carbon nanotubes obtained have a larger diameter due to the increase in catalyst particle size, but the structure remains intact, and no obvious graphite layer breakage or agglomeration was observed. In addition, a network-like cross-linked structure is formed between the carbon nanotubes, and the macroscopic structure still maintains a thin film appearance.

[0053] Comparative Example 1

[0054] A method for preparing a flexible carbon nanotube-based composite electrode material film, involving flame combustion experiments using ferrous sulfate as a catalyst without the application of a magnetic field, comprises the following steps:

[0055] 1) 2.0g of ferrous sulfate powder was ball-milled to a particle size of approximately 200nm and then loaded into a catalyst container;

[0056] 2) In a low-pressure chamber at 60 kPa, a mixture of methane and oxygen (volume flow ratio 2:1) is introduced at a total flow rate of 2000 mL / min to ignite and form a stable flame. Argon gas is then introduced at a flow rate of 100 mL / min to transport the catalyst particles to the center of the combustion flame.

[0057] The carbon nanotube film prepared in step 2) of this comparative example exhibits defects such as loose structure, disordered arrangement, and severe aggregation. Furthermore, it is prone to cracking during bending tests, and its mechanical stability and electrical conductivity are significantly lower than those of the sample prepared with a magnetic field. This indicates that the magnetic field plays a crucial role in promoting the orientation of carbon nanotubes and the compactness of the film.

[0058] Comparative Example 2

[0059] A method for preparing a flexible carbon nanotube-based composite electrode material thin film, using atmospheric pressure combustion conditions and a flame combustion experiment with a mixed catalyst of cobalt sulfate and ferrous sulfate, includes the following steps:

[0060] 1) Mix ferrous sulfate and cobalt sulfate at a mass ratio of 1:1 until homogeneous, then grind to submicron particles. Take 1.5g of the mixed powder and load it into the catalyst container.

[0061] 2) Under normal pressure, a mixture of methane and oxygen (volume flow ratio 2:1) is introduced at a total flow rate of 2500 mL / min to ignite and form a stable flame. Argon gas is then introduced at a flow rate of 200 mL / min to transport the catalyst particles to the center of the combustion flame.

[0062] 3) Activate the electromagnetic device to apply a vertical DC magnetic field of 3000 Gs. Carbon nanotubes are rapidly generated under the action of the catalyst, and under the induction of the magnetic field, they grow and cross-link in a vertical direction, depositing on the surface of the stainless steel mesh below to form a continuous, dense, flexible film.

[0063] The product obtained in step 3) of this comparative example has a relatively small deposition amount, and the carbon nanotube structure is a non-uniform short bundle, making it difficult to form thin film segments. Significant voids and inclusions exist, preventing the formation of a continuous flexible structure. This indicates that a low-pressure environment helps improve catalyst dispersion efficiency and uniform nucleation of carbon nanotubes, which is an important guarantee for the stable implementation of the process of this invention.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flexible carbon nanotube-based composite electrode material thin film, characterized in that, Includes the following steps: 1) The metal salt catalyst is refined to obtain metal salt catalyst particles, which are then loaded into a catalyst container; 2) The vacuum is drawn to a low pressure environment of 50-70 kPa in the closed reaction chamber, and methane and oxygen are introduced to form a stable diffusion combustion flame, which provides a high temperature heat source and carbon source for the growth of carbon nanotubes. The volume flow rate ratio of methane to oxygen is 2:1, and the total flow rate ranges from 1000 to 3000 mL / min. 3) Using argon gas to transport metal salt catalyst particles to the combustion reaction zone of the combustion flame, carbon nanotubes are catalyzed in the combustion flame, wherein the argon gas flow rate is 50-500 mL / min; 4) An electromagnetic device with a vertical DC magnetic field is set above the combustion zone. A magnetic field with a strength of 2000-5000 Gs is applied simultaneously during the growth of carbon nanotubes by the electromagnetic device. The magnetic force guides the carbon nanotubes to align in the direction of the magnetic field. Under the induction of the magnetic field, the carbon nanotubes grow in a vertical direction and cross-link and deposit on the surface of the stainless steel mesh below to form a continuous and dense flexible film.

2. The method for preparing a flexible carbon nanotube-based composite electrode material thin film according to claim 1, characterized in that: The metal salt catalyst is at least one selected from ferrous sulfate, ferric sulfate, cobalt sulfate, and nickel sulfate.

3. The method for preparing a flexible carbon nanotube-based composite electrode material thin film according to claim 1, characterized in that: The particle size of the metal salt catalyst particles is controlled to be 100-1000 nm.

4. The method for preparing a flexible carbon nanotube-based composite electrode material thin film according to claim 1, characterized in that: The distance between the electromagnetic device and the tip of the combustion flame is 80mm.

5. A flexible carbon nanotube-based composite electrode material film prepared by the method according to any one of claims 1 to 4, characterized in that: The film consists of oriented carbon nanotubes and metal salt catalyst particles. The carbon nanotubes grow vertically and cross-link to form a dense and continuous flexible network structure, while the metal salt catalyst particles are uniformly distributed on the carbon nanotube walls.

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