Carbon negative electrode material with carbon nanosheet array structure as well as preparation method and application of carbon negative electrode material

Abstract

The invention belongs to the technical field of sodium ion battery negative electrode materials, and particularly relates to a carbon negative electrode material with a carbon nanosheet array structure as well as a preparation method and application of the carbon negative electrode material. Comprising the following steps: immersing a carbon nanofiber film into an induction liquid, and carrying out a hydrothermal reaction to obtain a precursor; carrying out carbonization treatment on the precursor in protective gas, and immersing the carbonized precursor in an acid solution to remove metal nickel so as to obtain a carbon negative electrode material with a carbon nanosheet array structure; wherein a solute in the induction liquid is a mixture formed by glucose, soluble nickel salt and hexamethylenetetramine. A nickel hydroxide / nitrogen-containing polymer nanosheet array is grown on the surface of a carbon fiber through a hydrothermal method, the array structure is generated through induction of nickel hydroxide, then high-temperature carbonization treatment is conducted on the array structure, and the carbon negative electrode material with the grown carbon nanosheet array structure is obtained. And the problem of rapid capacity attenuation caused by volume expansion of the carbon material in the sodion embedding / de-embedding process can be effectively relieved.

Description

Technical Field

[0001] This invention belongs to the technical field of sodium-ion battery anode materials, specifically relating to a carbon anode material with a carbon nanosheet array structure, its preparation method, and its application. Background Technology

[0002] Sodium-ion batteries have outstanding advantages such as abundant resources, low cost, high safety, and environmental friendliness. Sodium reserves are far higher than lithium reserves, and the manufacturing process is highly compatible with existing lithium battery technology, which is conducive to rapid industrialization. At the same time, they have excellent low-temperature and high-rate performance and good cycle stability, making them particularly suitable for large-scale energy storage and other scenarios with higher requirements for cost and safety. Therefore, they have broad development prospects in the future new energy storage field.

[0003] Existing sodium-ion battery anode materials mainly include hard carbon, metal oxides / sulfides, alloys, titanates, and organic materials, each with its own advantages but also significant drawbacks. Metal oxides and sulfides offer high capacity but generally suffer from large volume expansion, low conductivity, and rapid cycle decay. Alloys possess ultra-high theoretical capacity, but their significant volume changes lead to poor stability. Titanates offer high safety and long cycle life, but their high operating potential results in lower energy density. Organic electrode materials offer good sustainability and designable structures, but suffer from poor conductivity, high solubility, and insufficient cycle stability. Overall, developing anode materials that combine high energy density, high initial efficiency, and long cycle life remains a core challenge in the sodium-ion battery field.

[0004] Carbon anode materials are currently the most commercially promising anode system for sodium-ion batteries, boasting advantages such as wide availability, low cost, and good conductivity. Furthermore, their structure is highly tunable, allowing for improvements in sodium storage performance through strategies like pore structure control and heteroatom doping, while remaining compatible with existing lithium-ion battery manufacturing systems. However, existing bulk carbon-based materials employ chemical activators such as KOH or introduce metal salts to treat precursors before carbonization, creating pores through physical or chemical processes to increase specific surface area and pore volume. This approach generally suffers from a lack of active sites and excessively long ion diffusion paths, leading to slow sodium-ion diffusion kinetics and potential electrode structure damage. Consequently, the capacity decays rapidly due to volume expansion during sodium-ion insertion / extraction. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon anode material with a carbon nanosheet array structure, its preparation method, and its application. A nickel hydroxide / nitrogen-containing polymer nanosheet array is grown on the surface of carbon fibers via a hydrothermal method, followed by high-temperature carbonization and acid removal of the metallic nickel to obtain a carbon anode material with a grown carbon nanosheet array structure. This provides a large number of exposed defects, edge sites, and heterogeneous interfaces, promoting rapid charge-discharge kinetics, which is beneficial for improving the reversible specific capacity of sodium storage, maximizing the interfacial contact between the electrode and the electrolyte, and constructing a rapid transport channel for electrons and sodium ions. Simultaneously, it effectively inhibits the recombination of nanosheets, which is beneficial for improving cycle life.

[0006] To achieve the above objectives, the specific technical solution provided by the present invention is as follows: The first objective of this invention is a method for preparing a carbon anode material with a nanosheet array structure, comprising the following steps: S1. The carbon nanofiber film is immersed in the induction solution and subjected to a hydrothermal reaction to grow a nickel hydroxide / nitrogen-containing polymer nanosheet array on the surface, thus obtaining the precursor.

[0007] S2. The precursor is carbonized in a protective gas to convert nickel hydroxide into metallic nickel, which is then encapsulated by carbon nanosheets. After carbonization, it is immersed in an acid solution to remove the metallic nickel, thus obtaining a carbon anode material with a carbon nanosheet array structure.

[0008] The solute in the induction solution is a mixture of carbon source, soluble nickel salt and hexamethylenetetramine.

[0009] Furthermore, the mass ratio of carbon source, soluble nickel salt, and hexamethylenetetramine is 1:1 to 3:2 to 4, the soluble nickel salt is sulfate, and the carbon source is glucose.

[0010] Furthermore, the hydrothermal reaction temperature is 140℃~200℃, and the time is 6h~24h.

[0011] Furthermore, the carbonization treatment temperature is 500℃~1000℃, the time is 1h~5h, the heating rate is 1℃ / min~5℃ / min, and the protective gas is argon.

[0012] Furthermore, the acid solution is a mixture of hydrochloric acid and nitric acid in a volume ratio of 10:1, with the concentration of hydrochloric acid being 12 mol / L and the concentration of nitric acid being 15 mol / L.

[0013] Furthermore, after immersion in an acid solution, it is left to stand at 70℃~90℃ for 7h~9h.

[0014] The second objective of this invention is to provide a carbon anode material with a carbon nanosheet array structure, which is prepared using the above-described preparation method.

[0015] A third objective of this invention is to provide the application of the above-described carbon anode material with a carbon nanosheet array structure in sodium-ion batteries.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing carbon anode materials with carbon nanosheet array structures. A nickel hydroxide / nitrogen-containing polymer nanosheet array is grown on the surface of carbon fibers via a hydrothermal method. This array is then subjected to high-temperature carbonization and acid removal of the metallic nickel to obtain the carbon anode material with the carbon nanosheet array structure. The carbon anode material based on the carbon nanosheet array structure has the following advantages: (1) High specific surface area and abundant active sites: Nanosheets provide a large number of exposed defects, edge sites, and heterogeneous interfaces, which is beneficial for improving the reversible sodium storage capacity. (2) Fast electron / ion transport pathways: Carbon fibers serve as a continuous conductive framework with low electron transport resistance; the short diffusion path of the nanosheets promotes rapid sodium ion migration, which is beneficial for high-rate performance. (3) High electrode structure stability: The vertical structure of the carbon nanosheets can alleviate volume expansion and contraction during sodium storage and prevent layer stacking, which is beneficial for improving cycle life. (4) Excellent electrolyte wettability and interfacial reaction: The open three-dimensional porous structure promotes full electrolyte wetting, thereby improving the kinetics of the electrode / electrolyte interface reaction. Attached Figure Description

[0017] Figure 1 This is a microstructure diagram of the carbon anode material with a carbon nanosheet array structure prepared in Example 1 of the present invention. Figure 1 In the image, a is a scanning electron microscope (SEM) image of carbon nanosheet array@carbon fiber, and b is a transmission electron microscope (TEM) image.

[0018] Figure 2 This is a scanning electron microscope image of the carbon anode material with a carbon nanosheet array structure prepared in Example 2 of the present invention. Figure 2 In the middle (a) and (b), scanning electron microscope images are shown at different sizes.

[0019] Figure 3 This is a scanning electron microscope image of the carbon anode material with a carbon nanosheet array structure prepared in Example 3 of the present invention. Figure 3 In the middle (a) and (b), scanning electron microscope images are shown at different sizes.

[0020] Figure 4 This is a microstructure diagram of the carbon anode material prepared in Comparative Example 1 of the present invention.

[0021] Figure 5 The X-ray diffraction pattern of the precursor of Example 1 of the present invention after carbonization treatment at 800°C is shown.

[0022] Figure 6This is an X-ray diffraction pattern of the carbonized material after being immersed in a solution formed by hydrochloric acid and nitric acid, as described in Example 1 of the present invention.

[0023] Figure 7 The electrochemical performance of the carbon anode material with a carbon nanosheet array structure in sodium-ion batteries according to Example 1 of this invention is shown. Figure 7 (a) and (b) show the rate performance and corresponding charge-discharge curves at different current densities, and (c) shows the long-cycle performance. Detailed Implementation

[0024] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] In recent years, various structurally regulated carbon materials have been reported for sodium ion storage, such as carbon nanosponges, porous carbon, carbon nanospheres, bowl-shaped carbon, and porous graphene. These materials have all shown promising prospects for sodium ion storage applications. However, the sodium storage mechanism of carbon materials is complex, with low initial coulombic efficiency, limited specific capacity, and significant performance differences between different structures. Further optimization of the structure and interface is needed to achieve higher energy density and improved practical application performance. Bulk carbon-based materials often employ chemical activators such as KOH or introduce metal salts to treat precursors before carbonization, creating pores through physical or chemical processes to increase specific surface area and pore volume. However, this approach generally suffers from a lack of active sites and excessively long ion diffusion paths, leading to slow sodium ion diffusion kinetics and potential electrode structure damage. This results in rapid capacity decay due to volume expansion during sodium ion insertion / extraction. Therefore, designing novel carbon-based anode materials rich in electrochemical active sites remains a formidable challenge.

[0027] Based on this, this invention grows a nickel hydroxide / nitrogen-containing polymer nanosheet array on the surface of carbon fiber using a hydrothermal method, followed by high-temperature carbonization and acid removal of metallic nickel to obtain a carbon anode material with a carbon nanosheet array structure. This carbon nanosheet structure possesses unique advantages. +The diffusion path facilitates rapid charge-discharge kinetics. Furthermore, this nanosheet structure maximizes the interfacial contact between the electrode and the electrolyte, enhancing the surface capacitance-dominated contribution during sodium ion storage. The two-dimensional nanosheet array structure not only promotes sufficient electrolyte wetting and constructs a rapid electron-sodium ion transport channel, but also effectively suppresses nanosheet recombination. This effectively alleviates the problem of rapid capacity decay caused by volume expansion during sodium ion insertion / extraction in carbon materials. Specifically:

[0028] A method for preparing a carbon anode material with a carbon nanosheet array structure includes the following steps: S1. The carbon nanofiber film is immersed in the induction solution and subjected to a hydrothermal reaction to grow a nickel hydroxide / nitrogen-containing polymer nanosheet array on the surface, thus obtaining the precursor.

[0029] In this invention, the solute in the induction solution is a complex formed by a carbon source, a soluble nickel salt, and hexamethylenetetramine, with a mass ratio of 1:1 to 3:2 to 4. The soluble nickel salt is a sulfate. The solvent can be a solution that completely dissolves the solute. As a preferred embodiment of this invention, the solvent is deionized water, with a mass-to-volume ratio of 1.7 g to 40 mL for the solute. Glucose, the soluble nickel salt, and hexamethylenetetramine are dissolved in deionized water to form a homogeneous solution, thus obtaining the induction solution. The carbon source is glucose. Hexamethylenetetramine reacts with glucose to generate a nitrogen-containing polymer, thereby forming a surface-grown nickel hydroxide / nitrogen-containing polymer nanosheet array.

[0030] During the hydrothermal reaction, the temperature ranges from 140℃ to 200℃, and the reaction time ranges from 6 hours to 24 hours.

[0031] In this invention, the method for preparing carbon nanosheet array thin films includes the following steps: Polymer nanofibers were prepared by electrospinning, and then carbonized to obtain carbon nanofiber films. To prepare the carbon fiber films, 1 g of polyacrylonitrile (PAN) was dissolved in 10 mL of N,N-dimethylformamide (DMF) and stirred for 12 hours. The resulting solution was then transferred to a plastic syringe, and an 18 kV operating voltage was maintained between the receiver and the needle, with a flow rate of 0.8 mL / h. -1 Electrospinning was performed at a flow rate of [missing information]. After the precursor film was cured in air, it was annealed at 800°C for 2 hours in an argon atmosphere to obtain a carbon nanofiber film.

[0032] S2. The precursor is carbonized in a protective gas to convert nickel hydroxide into metallic nickel, which is then encapsulated by carbon nanosheets. After carbonization, it is immersed in an acid solution to remove the metallic nickel, thus obtaining a carbon anode material with a carbon nanosheet array structure.

[0033] In this invention, during the high-temperature carbonization process, the nitrogen-containing polymer is transformed into carbon nanosheets; after carbonization, it is immersed in an acid solution, where the metallic nickel particles react with hydrochloric acid and nitric acid in the mixed acid to generate nickel nitrate, nickel chloride and water; nickel nitrate and nickel chloride are easily soluble in water, thereby removing the metallic nickel particles from the carbon nanosheets and obtaining a carbon anode material with a carbon nanosheet array structure.

[0034] In this invention, the carbonization temperature is 500℃~1000℃, the time is 1h~5h, the heating rate is 1℃ / min~5℃ / min, and the protective gas is argon.

[0035] In this invention, after carbonization, the material is immersed in an acid solution and left to stand at 70°C–90°C for 7–9 hours. After standing, it is washed with deionized water and dried to obtain a carbon anode material with a carbon nanosheet array structure. The acid solution is a mixture of hydrochloric acid and nitric acid in a volume ratio of 10:1, with the hydrochloric acid concentration being 12 mol / L and the nitric acid concentration being 15 mol / L.

[0036] In summary, this invention grows a nickel hydroxide / nitrogen-containing polymer nanosheet array on the surface of carbon fiber using a hydrothermal method. The array structure is induced by nickel hydroxide and then subjected to high-temperature carbonization treatment, in which nickel hydroxide is converted into metallic nickel and encapsulated by carbon nanosheets. Finally, the metallic nickel is removed with acid to obtain a carbon anode material with a carbon nanosheet array structure, which is used as a carbon anode material for sodium-ion batteries. Its advantages and mechanisms can be summarized as follows: (1) High specific surface area and abundant active sites: Nanosheets provide a large number of exposed defects, edge sites and heterogeneous interfaces, which is beneficial to improving the reversible specific capacity of sodium storage. (2) Fast electron / ion transport pathway: Carbon fiber, as a continuous conductive skeleton, has low resistance to electron transport; the nanosheet structure shortens the diffusion path, which promotes the rapid migration of sodium ions and is beneficial to high rate performance. (3) High electrode structure stability: The vertical structure of carbon nanosheets can alleviate the volume expansion and contraction during sodium storage and prevent the stacking of sheets, which is beneficial to improving cycle life. (4) Excellent electrolyte wettability and interfacial reaction: The open three-dimensional porous structure promotes full electrolyte wetting, thereby enhancing the kinetics of the electrode / electrolyte interface reaction.

[0037] The following specific examples will provide further explanation.

[0038] Example 1 A method for preparing a carbon anode material with a carbon nanosheet array structure includes the following steps: S1. Using electrospinning, 1g of PAN was dissolved in 10mL of DMF and stirred for 12h to obtain a precursor solution. The obtained precursor solution was transferred to a plastic syringe, and an 18kV working voltage was maintained between the receiver and the syringe needle, with a flow rate of 0.8mL·h. -1Electrospinning was performed at a flow rate of [value missing]. After the precursor film was cured in air, it was annealed at 800°C for 2 hours in an argon atmosphere to finally obtain a carbon nanofiber film.

[0039] S2. Dissolve 0.35g glucose, 0.6g nickel sulfate, and 0.6g hexamethylenetetramine in 40mL of deionized water to prepare a homogeneous solution and obtain the induction solution. Immerse the carbon nanofiber film in the induction solution and carry out a hydrothermal reaction at 180℃ for 10h. After the reaction is completed, allow the temperature to cool naturally, wash with deionized water and dry to obtain the precursor.

[0040] S3. In an argon atmosphere, the precursor was carbonized at 800℃ for 2 hours. After carbonization, it was immersed in a solution of hydrochloric acid and nitric acid and allowed to stand at 80℃ for 8 hours. The volume ratio of hydrochloric acid to nitric acid was 10:1, the concentration of hydrochloric acid was 12 mol / L, and the concentration of nitric acid was 15 mol / L to remove metallic nickel. The precursor was then washed with deionized water and dried to obtain a carbon anode material with a carbon nanosheet array structure.

[0041] Example 2 A method for preparing a carbon anode material with a carbon nanosheet array structure includes the following steps: S1. Using electrospinning, 1g of PAN was dissolved in 10mL of DMF and stirred for 12h to obtain a precursor solution. The obtained precursor solution was transferred to a plastic syringe, and an 18kV working voltage was maintained between the receiver and the syringe needle, with a flow rate of 0.8mL·h. -1 Electrospinning was performed at a flow rate of [value missing]. After the precursor film was cured in air, it was annealed at 800°C for 2 hours in an argon atmosphere to finally obtain a carbon nanofiber film.

[0042] S2. Dissolve 0.35g glucose, 0.6g nickel sulfate, and 0.6g hexamethylenetetramine in 40mL of deionized water to prepare a homogeneous solution and obtain the induction solution. Immerse the carbon nanofiber film in the induction solution and carry out a hydrothermal reaction at 160℃ for 10h. After the reaction is completed, allow the temperature to cool naturally, wash with deionized water and dry to obtain the precursor.

[0043] S3. In an argon atmosphere, the precursor was carbonized at 800℃ for 2 hours. After carbonization, it was immersed in a solution of hydrochloric acid and nitric acid and allowed to stand at 80℃ for 8 hours. The volume ratio of hydrochloric acid to nitric acid was 10:1, the concentration of hydrochloric acid was 12 mol / L, and the concentration of nitric acid was 15 mol / L to remove metallic nickel. The precursor was then washed with deionized water and dried to obtain a carbon anode material with a carbon nanosheet array structure.

[0044] Example 3 A method for preparing a carbon anode material with a carbon nanosheet array structure includes the following steps: Electrospinning was used to dissolve 1 g of PAN in 10 mL of DMF and stir for 12 h to obtain a precursor solution. The resulting precursor solution was transferred to a plastic syringe, and an 18 kV operating voltage was maintained between the receiver and the syringe needle, with a spinning rate of 0.8 mL / h. -1 Electrospinning was performed at a flow rate of [value missing]. After the precursor film was cured in air, it was annealed at 800°C for 2 hours in an argon atmosphere to finally obtain a carbon nanofiber film.

[0045] S2. Dissolve 0.35g glucose, 0.35g nickel sulfate, and 0.6g hexamethylenetetramine in 40mL of deionized water to prepare a homogeneous solution and obtain the induction solution. Immerse the carbon nanofiber film in the induction solution and carry out a hydrothermal reaction at 180℃ for 10h. After the reaction is completed, allow the temperature to cool naturally, wash with deionized water and dry to obtain the precursor.

[0046] S2. In an argon atmosphere, the precursor was carbonized at 800℃ for 2 hours. After carbonization, it was immersed in a solution of hydrochloric acid and nitric acid and allowed to stand at 80℃ for 8 hours. The volume ratio of hydrochloric acid to nitric acid was 10:1, the concentration of hydrochloric acid was 12 mol / L, and the concentration of nitric acid was 15 mol / L to remove metallic nickel. The precursor was then washed with deionized water and dried to obtain a carbon anode material with a carbon nanosheet array structure.

[0047] Comparative Example 1 A method for preparing a carbon anode material includes the following steps: S1. Polyacrylonitrile nanofibers were prepared by electrospinning and then carbonized to obtain carbon nanofiber films.

[0048] S2. Dissolve 0.35g glucose and 0.6g hexamethylenetetramine in 40mL of deionized water to prepare a homogeneous solution and obtain the induction solution. Immerse the carbon nanofiber film in the induction solution and carry out a hydrothermal reaction at 180℃ for 10h. After the reaction is completed, allow the temperature to cool naturally, wash with deionized water and dry to obtain the precursor.

[0049] S2. In an argon atmosphere, the precursor is carbonized at 800°C for 2 hours. After carbonization, a carbon anode material with a carbon nanosphere structure is obtained.

[0050] The carbon anode materials prepared in Examples 1 to 3 and Comparative Example 1 were subjected to structural and performance tests.

[0051] Figure 1 This is a microstructure diagram of the carbon anode material with a carbon nanosheet array structure prepared in Example 1 of the present invention. Figure 1 Image a is a scanning electron microscope (SEM) image, and image b is a transmission electron microscope (TEM) image. Figure 1As shown, carbon nanosheets with an array structure grow vertically on the surface of carbon fibers, exhibiting a unique structure.

[0052] Figure 2 This is a scanning electron microscope image of the carbon anode material with a carbon nanosheet array structure prepared in Example 2 of the present invention. Figure 2 In the image, (a) and (b) are scanning electron microscope images at different sizes. Figure 2 As shown, at 160℃, the array structure of carbon nanosheets is not obvious, and the carbon nanosheets are wrinkled and covered on the surface of carbon fibers.

[0053] Figure 3 This is a scanning electron microscope image of the carbon anode material with a carbon nanosheet array structure prepared in Example 3 of the present invention. Figure 3 In the image, (a) and (b) are scanning electron microscope images at different sizes. Figure 2 As shown. Figure 3 As shown, when 0.35g of nickel sulfate is added, the carbon nanosheets are relatively thick and small in size, and the array structure is not obvious.

[0054] Figure 4 This is a microstructure diagram of the carbon anode material prepared in Comparative Example 1 of this invention. Figure 4 As shown, when there is no nickel sulfate in the induction solution, there is no induction effect of nickel hydroxide in the hydrothermal reaction process, and carbon nanosheet structure is not obtained, but carbon nanosphere structure.

[0055] Figure 5 This is an X-ray diffraction pattern of the precursor of Example 1 of the present invention after carbonization treatment at 800°C. Figure 5 As shown, after carbonization at 800℃, nickel hydroxide is converted into metallic nickel.

[0056] Figure 6 This is an X-ray diffraction pattern of the carbonized material after immersion in a solution formed by hydrochloric acid and nitric acid, as described in Example 1 of the present invention. Figure 6 As shown, after carbonization, metallic nickel is removed by immersion in mixed acid.

[0057] The carbon anode material with a carbon nanosheet array structure prepared in Example 1 was used in a sodium-ion battery. The specific steps are as follows: Electrochemical performance testing was conducted using CR2032 coin cells. The carbon anode material with a carbon nanosheet array structure from Example 1 was cut into 14mm diameter discs and used as a self-supporting anode material to assemble the cells. The electrolyte was a propylene carbonate (PC) solution containing 1M NaClO4. A glass fiber membrane (Whatman, GF / D) was used as the separator, and a sodium metal sheet was used as the counter electrode. All cell assembly was performed in an argon-filled glove box. Constant current charge-discharge tests were conducted on a CT2001A battery testing system (LAND Electronic Co.), with a test voltage range of 0.01V to 3.0V (relative to Na / Na). + ).

[0058] Figure 7 The electrochemical performance of the carbon anode material with a carbon nanosheet array structure in sodium-ion batteries according to Example 1 of this invention is shown. Figure 7 In Figure (a) and (b), the rate performance and corresponding charge-discharge curves are shown at different current densities, and in Figure (c), the long-cycle performance is shown. Figure 7 As shown in (a) and (b), carbon anode materials with carbon nanosheet array structures at 0.1 A·g -1 0.2A·g -1 0.5A·g -1 1A·g -1 2A·g -1 5A·g -1 10A·g -1 and 15A·g -1 At current densities of 341 mAh·g, respectively −1 280.3mAh·g −1 230.9mAh·g −1 195.2 mAh·g −1 167.1mAh·g −1 143.2 mAh·g −1 120.7mAh·g −1 112.5mAh·g −1 The reversible specific capacity exhibits excellent rate performance. This is because the unique nanosheet array structure can shorten the diffusion path of sodium ions and expose more sodium storage active sites, thereby improving the reactivity of sodium ions. Figure 3 As shown in (c), in 2A·g −1 After 2000 cycles at a current density, the reversible specific capacity is 152.7 mAh g. −1The nanosheet array structure provides space for the expansion / contraction of the electrode volume during charge and discharge, thereby mitigating changes in electrode volume and maintaining the stability of the electrode material structure. Furthermore, the array structure can suppress the stacking of carbon nanosheets during charge-discharge cycling, further preserving the cycle capacity.

[0059] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a carbon anode material with a carbon nanosheet array structure, characterized in that, Includes the following steps: Carbon nanofiber films are immersed in an induction solution to carry out a hydrothermal reaction, which grows a nickel hydroxide / nitrogen-containing polymer nanosheet array on the surface to obtain a precursor. The precursor is carbonized in a protective gas to convert nickel hydroxide into metallic nickel, which is then encapsulated by carbon nanosheets. After carbonization, it is immersed in an acid solution to remove the metallic nickel, thus obtaining a carbon anode material with a carbon nanosheet array structure. The solute in the induction solution is a mixture of carbon source, soluble nickel salt and hexamethylenetetramine.

2. The method for preparing the carbon anode material with a carbon nanosheet array structure according to claim 1, characterized in that, The mass ratio of carbon source, soluble nickel salt and hexamethylenetetramine is 1:1 to 3:2 to 4, the soluble nickel salt is sulfate, and the carbon source is glucose.

3. The method for preparing the carbon anode material with a carbon nanosheet array structure according to claim 1, characterized in that, The hydrothermal reaction temperature is 140℃~200℃, and the time is 6h~24h.

4. The method for preparing the carbon anode material with a carbon nanosheet array structure according to claim 1, characterized in that, The carbonization treatment temperature is 500℃~1000℃, the time is 1h~5h, the heating rate is 1℃ / min~5℃ / min, and the protective gas is argon.

5. The method for preparing the carbon anode material with a carbon nanosheet array structure according to claim 1, characterized in that, The acid solution is a mixture of hydrochloric acid and nitric acid in a volume ratio of 10:1, with the concentration of hydrochloric acid being 12 mol / L and the concentration of nitric acid being 15 mol / L.

6. The method for preparing the carbon anode material with a carbon nanosheet array structure according to claim 1, characterized in that, After immersing in acid solution, let stand at 70℃~90℃ for 7h~9h.

7. A carbon anode material with a carbon nanosheet array structure, characterized in that, It is prepared by the preparation method obtained by any one of claims 1 to 6.

8. The application of the carbon anode material with a carbon nanosheet array structure as described in claim 7 in a sodium-ion battery.

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