A kind of neuron-like structure anode material, its preparation method and application

Abstract

The present invention discloses a neuron-like structure anode material, its preparation method and application. Graphene oxide and carbon nanotubes are assembled by a one-step hydrothermal self-assembly method. The process is simple and does not require expensive equipment, making it suitable for large-scale production. Through hydrogen bond assembly between graphene oxide and carbon nanotubes, a biomimetic structure with a three-dimensional interconnected network and hierarchical pores is formed, significantly optimizing the ion diffusion path and electron transport efficiency. This anode material exhibits high specific capacity and long cycle stability under fast charge and discharge conditions, and can still maintain a high capacity in a low-temperature environment, breaking through the performance bottleneck of traditional carbon-based materials under extreme conditions. It is applied to energy storage devices including but not limited to high-power lithium-ion / sodium-ion batteries and supercapacitors, and is suitable for low-temperature / quick-charge scenario requirements including but not limited to electric vehicles and aerospace.

Description

Technical Field

[0001] The present invention relates to the technical fields of electrochemistry and new energy materials, and in particular to a neuron-like structure anode material, a preparation method thereof, and an application thereof. Background Art

[0002] With the surge in the demand for electric vehicles, portable electronic devices, and energy storage in extreme environments, the limitations of traditional lithium-ion battery anode materials (such as graphite and silicon-based materials) have become increasingly prominent. Although graphite materials are stable, their theoretical capacity is low (372 mAh / g), lithium precipitation is likely to occur during fast charging, leading to safety hazards, and the ion diffusion rate drops sharply at low temperatures, resulting in a significant attenuation of capacity; although silicon-based materials have a high capacity, the huge volume expansion during charge and discharge causes the structure to powder, and the cycle life drops sharply. Optimizing conductivity and ion transport by constructing carbon-based heterostructures (such as graphene / carbon nanotube composites) is an effective strategy, but traditional heterointerfaces mostly rely on physical stacking, with poor interface stability and ion transport bottlenecks likely to occur at extreme rates or low temperatures. The preparation of traditional heterostructures often requires complex processes such as high-temperature annealing and chemical vapor deposition, resulting in high costs and large energy consumption.

[0003] Two-dimensional carbon-based heterostructures have become a research hotspot for breaking through the above bottlenecks due to their unique interface coupling effect. As a new type of sp-sp² hybrid carbon material, graphitic oxide has excellent charge transport potential due to its rich surface functional groups and three-dimensional through-hole structure; while carbon nanotubes with an edge-active-site-density advantage and a one-dimensional hollow topological structure have significant advantages in constructing a fast ion transport network. However, existing research has mostly focused on the modification and optimization of single carbon materials, lacking a systematic understanding of the synergistic mechanism of multi-dimensional carbon-based heterointerfaces. In particular, the key technology of constructing biomimetic ion channels through non-covalent bonds has not yet achieved a breakthrough. Summary of the Invention

[0004] In order to overcome the above problems existing in the prior art, the present invention proposes a neuron-like structure anode material, a preparation method thereof, and an application thereof.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a neuron-like structure anode material, including graphitic oxide and carbon nanotubes, the graphitic oxide is obtained by oxidizing graphdiyne, the carbon nanotubes are obtained by nitric acid oxidation method, and the heterostructure obtained by hydrothermal synthesis of the graphitic oxide and carbon nanotubes is the anode material.

[0006] For the above-mentioned neuron-like structure anode material, the diameter of the carbon nanotubes is 6-8 nm.

[0007] A preparation method of a neuron-like structure anode material specifically includes the following steps:

[0008] Step 1, Preparation of graphdiyne: Add pyridine into a three-necked flask containing a copper sheet, then add hexakis(ethynyl)benzene to it, heat to 110 °C, and reflux for 72 h. Place the copper sheet with grown graphdiyne in hydrochloric acid and ultrasonicate, then filter by suction, wash, and dry to obtain graphdiyne polymer;

[0009] Step 2, Preparation of oxidized graphdiyne: Place the graphdiyne polymer obtained in Step 1 into a single-necked flask, add a magnetic stir bar, dropwise add concentrated sulfuric acid under an ice-water bath condition, then dropwise add hydrogen peroxide, stir under the ice-water bath for 5 min, transfer it to room temperature and stir for 1 h. After the reaction ends, add a large amount of deionized water to quench the reaction, centrifuge, and dry to obtain oxidized graphdiyne;

[0010] Step 3, Preparation of oxidized carbon nanotubes: Place multi-walled carbon nanotubes in a dry single-necked flask equipped with a condenser, slowly add 9 M HNO3, reflux the mixture at 75 °C for 24 h, then filter by suction, wash, and dry to obtain oxidized carbon nanotubes;

[0011] Step 4, Preparation of oxidized graphdiyne / oxidized carbon nanotube heterostructure material: Place the oxidized graphdiyne obtained in Step 2 and the oxidized carbon nanotubes obtained in Step 3 in a single-necked flask equipped with a magnetic stir bar according to a mass ratio of 3:7, add deionized water, ultrasonically disperse for 5 min, then stir and reflux under heating at 80 °C for 24 h to make them fully contact to obtain a heterostructure.

[0012] In the above preparation method of a neuron-like structure anode material, the ratio of pyridine to the copper sheet in Step 1 is 150 mL: 20 copper sheets with a size of 1 cm × 5 cm.

[0013] In the above preparation method of a neuron-like structure anode material, the volume ratio of concentrated sulfuric acid to hydrogen peroxide in Step 2 is 7:3.

[0014] An application of a neuron-like structure anode material, such as the above neuron-like structure anode material or the neuron-like structure anode material prepared by the above preparation method of a neuron-like structure anode material, is applied to energy storage devices including but not limited to high-power lithium-ion / sodium-ion batteries and supercapacitors, and is suitable for low-temperature / quick-charge scenario requirements including but not limited to electric vehicles and aerospace.

[0015] The beneficial effect of the present invention is that the present invention designs a bionic neuron topological structure: oxidized graphdiyne and oxidized carbon nanotubes are directionally bonded by hydrogen bonds to form a three-dimensional bionic neural network structure, realizing the optimization of the ion transport path, reducing the ion diffusion tortuosity, increasing the lithium-ion diffusion coefficient and the lithium-ion diffusion rate under low-temperature conditions.

[0016] The present invention innovatively utilizes the oxygen-containing functional groups on the surface of GDYO and OCNTs to achieve hydrogen-bond-guided assembly through a one-step hydrothermal method, avoiding the destruction of the material structure by high-temperature treatment, and constructing a three-dimensional heterostructure by a low-energy and efficient method.

[0017] The present invention constructs a built-in electric field by utilizing the work function difference between graphitic carbon nitride and carbon nanotubes oxidized, accelerating the migration and diffusion of lithium ions. Therefore, this material has excellent fast-charging performance.

[0018] The heterostructure of the present invention has excellent fast-charging ability, which is attributed to the rapid lithium-ion migration of the neuron biomimetic structure.

[0019] The heterostructure of the present invention has extreme temperature adaptability: at a low temperature of -20 °C, it can still maintain a high capacity under high-rate charge and discharge, and at a high temperature of 50 °C, it maintains high-stability cycling under high-rate charge and discharge, with almost no attenuation of the capacity. Brief Description of the Drawings

[0020] Figure 1 is the scanning electron microscope image of the heterostructure anode material prepared in Example 1 of the present invention;

[0021] Figure 2 is the transmission electron microscope image of the heterostructure anode material prepared in Example 1 of the present invention;

[0022] Figure 3 is the atomic force microscope image of the heterostructure anode material prepared in Example 1 of the present invention;

[0023] Figure 4 is the KPFM image of the heterostructure anode material prepared in Example 1 of the present invention;

[0024] Figure 5 is the CV curve graph of the heterostructure anode material in Example 1 of the present invention;

[0025] Figure 6 is the CV curve graph at 1 mV / s of the heterostructure anode material in Example 1 of the present invention;

[0026] Figure 7 is the GITT test of the heterostructure anode material in Example 1 of the present invention and the calculated lithium-ion diffusion coefficient;

[0027] Figure 8 is the rate performance test of the heterostructure anode material in Example 1 of the present invention and the control example;

[0028] Figure 9 is the cycling performance test at 2 A / g of the heterostructure anode material in Example 1 of the present invention and the comparative example;

[0029] Figure 10This is the cyclic performance test of the heterogeneous structure anode material in Example 1 of the present invention and the comparative example at 10 A / g. Detailed implementation mode

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific implementation modes.

[0031] This embodiment discloses a neuron-like structure anode material, which includes graphitic carbon nitride and oxidized carbon nanotubes. The mass of graphitic carbon nitride is 18 mg, and the oxidized carbon nanotubes are 42 mg. The diameter of the carbon nanotubes is 6-8 nm. The graphitic carbon nitride is obtained by oxidizing graphite alkyne, and the oxidized carbon nanotubes are obtained by nitric acid oxidation method. The heterogeneous structure obtained by hydrothermal synthesis of the graphitic carbon nitride and the oxidized carbon nanotubes is the anode material.

[0032] Graphite alkyne is a new type of carbon material suitable for the anode of fast-charging batteries. However, it is difficult to construct a heterogeneous structure using graphite alkyne due to the stability of the graphite alkyne sheets. Therefore, oxidizing graphite alkyne to make the edges of graphite alkyne contain highly active oxygen-containing groups is an effective method for constructing a graphite alkyne heterogeneous structure. Carbon nanotubes have long-range ordered channels to supply the shuttle migration and diffusion of lithium ions, and their intrinsic structure has high conductivity. Heterogenizing the two is expected to obtain a high-quality anode material for fast-charging lithium-ion batteries.

[0033] A preparation method of a neuron-like structure anode material includes the following steps:

[0034] Step 1, preparation of graphite alkyne: First, add pyridine to a three-necked flask containing a copper sheet, then add hexaynylbenzene to it, heat to 110 °C, and reflux for 72 h. Place the copper sheet with grown graphite alkyne in hydrochloric acid and ultrasonicate, then filter and wash and dry to obtain a graphite alkyne polymer.

[0035] Step 2, preparation of graphitic carbon nitride: Graphitic carbon nitride is obtained by mild oxidation of graphite alkyne. Place the graphite alkyne in a single-necked flask, add a magnetic stirrer, dropwise add concentrated sulfuric acid under an ice-water bath condition, then dropwise add hydrogen peroxide, stir for 5 min under the ice-water bath, and transfer it to room temperature and stir for 1 h. After the reaction is completed, add a large amount of deionized water to quench the reaction, and centrifuge, filter, and freeze-dry to obtain graphitic carbon nitride.

[0036] Step 3, preparation of oxidized carbon nanotubes: Place multi-walled carbon nanotubes in a dry 50 mL single-necked flask equipped with a condenser, slowly add 9 M HNO3, reflux the mixture at 75 °C for 24 h, and after completion, filter, wash, and dry to obtain oxidized carbon nanotubes.

[0037] Step 4, Preparation of graphdiyne / oxidized carbon nanotube heteromaterial: Place the obtained graphdiyne and oxidized carbon nanotubes in a single-necked flask equipped with a magnetic stir bar according to a mass ratio of 3:7, add deionized water, ultrasonically disperse for 5 min, and then stir and reflux under heating at 80 °C for 24 h to allow them to fully contact and obtain a heterostructure.

[0038] In this embodiment, the ratio of pyridine to copper sheets in Step 1 is 150 mL: 20 copper sheets sized 1 cm × 5 cm. The volume ratio of concentrated sulfuric acid to hydrogen peroxide in Step 2 is 7:3. Example

[0039] Under argon protection, add 100 mg of hexaethynylbenzene to a single-necked flask containing 10 copper sheets sized 1 cm × 5 cm, add 150 mL of pyridine, and react at 110 °C for 72 h to obtain copper sheets with graphdiyne grown on them. Rinse the copper sheets with deionized water, then add them to a 200 mL 3 M HCl solution and ultrasonicate to detach the graphdiyne from the copper sheets. Then, obtain graphdiyne through suction filtration, washing, and drying.

[0040] Under an ice-water bath condition, add a magnetic stir bar and 100 mg of graphdiyne to a single-necked flask. While stirring slowly, add 7 mL of concentrated sulfuric acid and gradually increase the stirring speed until all is added. Then, dropwise add 3 mL of hydrogen peroxide. After all is added, stir in the ice-water bath for 5 min, then transfer the single-necked flask to room temperature and stir at room temperature for 60 min. Add 400 mL of deionized water to quench the reaction. Centrifuge the obtained mixture. After centrifugation, take the lower-layer solid, add deionized water and continue centrifuging until the solution tested with pH paper shows neutrality. Freeze-dry it to obtain 40 mg of graphdiyne oxide.

[0041] Add 80 mL of 9 M nitric acid to a single-necked flask, add 500 mg of carbon nanotubes, stir at 80 °C for 24 h, and obtain oxidized carbon nanotubes through suction filtration, washing, and drying.

[0042] Add 42 mg of oxidized carbon nanotubes and 18 mg of graphdiyne oxide to a single-necked flask, add a stir bar, and stir at 60 °C for 12 h to obtain a heterostructure material. Example

[0043] Under argon protection, add 100 mg of hexaethynylbenzene to a single-necked flask containing 10 copper sheets sized 1 cm × 5 cm, add 150 mL of pyridine, and react at 110 °C for 72 h to obtain copper sheets with graphdiyne grown on them. Rinse the copper sheets with deionized water, then add them to a 200 mL 3 M HCl solution and ultrasonicate to detach the graphdiyne from the copper sheets. Then, obtain graphdiyne through suction filtration, washing, and drying.

[0044] Under the condition of an ice-water bath, a magnetic stir bar and 100 mg of graphdiyne were added to a single-neck flask. While stirring slowly, 7 mL of concentrated sulfuric acid was added and the stirring speed was gradually increased. After all the sulfuric acid was added, 3 mL of hydrogen peroxide was added drop by drop. After all the hydrogen peroxide was added, the mixture was stirred in the ice-water bath for 5 min, then the single-neck flask was transferred to room temperature and stirred at room temperature for 60 min. 400 mL of deionized water was added to quench the reaction. The resulting mixture was centrifuged. After centrifugation, the lower-layer solid was taken, and deionized water was added again for centrifugation until the solution tested with pH paper showed neutrality. Then it was freeze-dried to obtain 40 mg of oxidized graphdiyne.

[0045] 42 mg of carbon nanotubes and 18 mg of oxidized graphdiyne were added to a single-neck flask, a stirring bar was added, and the mixture was stirred at 60 °C for 12 h to obtain a heterostructure material.

[0046] The electrical property test method for the above Example 1 and Comparative Example was as follows: The obtained electrode material was placed on a copper foil to make a negative electrode sheet, which was assembled with a lithium metal sheet into a coin cell. The electrolyte was 1 mol / L LiPF6 dissolved in DMC, and the battery rate performance, cycling performance and other electrochemical performances were tested.

[0047] Figure 1 This is the scanning electron microscope image of the oxidized graphdiyne / carbon-oxidized carbon nanotube heterostructure negative electrode material prepared in Example 1 of the present invention. From Figure 1 it can be observed that the oxidized graphdiyne / carbon-oxidized carbon nanotube heterostructure presents a neuron-like structure. The sheet structure of GDYO serves as the "neuron cell body", providing abundant active sites and ion storage spaces; OCNTs extend as "axons" to form a continuous conductive path.

[0048] Figure 2 This is the transmission electron microscope image of the oxidized graphdiyne / carbon-oxidized carbon nanotube heterostructure negative electrode material prepared in Example 1 of the present invention. A heterostructure similar to a neuron can also be observed.

[0049] Figure 3 This is the atomic force microscope image of the oxidized graphdiyne / carbon-oxidized carbon nanotube heterostructure negative electrode material prepared in Example 1 of the present invention. From the figure, it can be observed that there is a certain height difference in the heterostructure, and the carbon nanotubes in it diverge around like star rays.

[0050] Figure 4 This is the KPFM image of the oxidized graphdiyne / carbon-oxidized carbon nanotube heterostructure negative electrode material prepared in Example 1 of the present invention, which is used to characterize that oxidized graphdiyne and carbon-oxidized carbon nanotubes with different work functions constitute an interfacial built-in electric field. Under the action of the built-in electric field, the heterostructure has ultrafast lithium-ion diffusion kinetics.

[0051] Figure 5This is the CV curve of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention. The b value is calculated and fitted through different scanning rates to indicate the kinetic characteristics of the battery. The results show that the b value is close to 1, indicating that the lithium ion diffusion behavior of the material is dominated by the fast pseudocapacitance behavior on the surface. Therefore, it has excellent rate performance.

[0052] Figure 6 This is the CV curve of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention at 1 mV / s, which is used to calculate the proportion of pseudocapacitance at a scanning rate of 1 mV / s. The results show that the proportion of pseudocapacitance is 73%.

[0053] Figure 7 This is the GITT test of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention and the calculated lithium ion diffusion coefficient. The lithium ion diffusion coefficient of this heteromaterial is between 10 -8 and 10 -9 indicating that its lithium ion diffusion behavior is excellent and it has good fast charging performance.

[0054] Figure 8 This is the rate performance test of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention and the control example. The results show that the capacities of the two materials are close at 0.1 A / g, but at a current density of 2 A / g and above, the gap between them is large. The heterostructure has excellent rate performance and can still maintain a high capacity even at a large current density of 10 A / g.

[0055] Figure 9 This is the cycle performance test of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention and the comparative example at 2 A / g. Its capacity is much higher than that of the comparative example.

[0056] Figure 10 This is the cycle performance test of the graphite carbon nitride / carbon nanotube carbon heterostructure anode material prepared in Example 1 of the present invention and the comparative example at 10 A / g. Its capacity is much higher than that of the comparative example.

[0057] The material of the present invention is assembled through hydrogen bonds between graphyne oxide and carbon nanotubes oxidized to form a bionic structure with a three-dimensional interconnected network and multi-level pores, significantly optimizing the ion diffusion path and electron transport efficiency. This anode material exhibits high specific capacity and long cycle stability under fast charge and discharge conditions, and can still maintain a high capacity in a low-temperature environment, breaking through the performance bottleneck of traditional carbon-based materials under extreme conditions. Among them, (1) strong hydrogen bond networks are formed by using the oxygen-containing functional groups on the surface of GDYO and the hydroxyl / carboxyl groups of OCNTs to construct a highly stable heterogeneous interface; (2) the neuron-like topological structure enables the dual high-speed transport of ions / electrons through multi-scale pores (micropore-mesopore synergy) and a continuous conductive framework; (3) the material is prepared by a one-step hydrothermal self-assembly method, with a simple process and no need for expensive equipment, suitable for large-scale production. This invention is applicable to energy storage devices such as high-power lithium-ion / sodium-ion batteries and supercapacitors, and is particularly targeted at the low-temperature / quick-charge scenarios of electric vehicles, aerospace, etc., with important commercial value.

[0058] The above embodiments are only exemplary embodiments of the present invention and are not used to limit the present invention. Those skilled in the art can make various modifications or equivalent replacements to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present invention.

Claims

1. A preparation method of a negative electrode material with a neuron-like structure, characterized in that, The negative electrode material includes oxidized graphene and oxidized carbon nanotubes, wherein the oxidized graphene is obtained by oxidizing graphene, and the oxidized carbon nanotubes are obtained by nitric acid oxidation. The heterogeneous structure obtained by synthesizing the oxidized graphene and the oxidized carbon nanotubes by hydrothermal method is the negative electrode material; The carbon nanotube has a diameter of 6-8 nm; The specific steps include: Step 1, preparation of graphyne: under argon protection, pyridine is added into a three-necked flask containing a copper sheet, and then hexynylbenzene is added thereto, heated to 110° C., refluxed for 72 h, and the obtained copper sheet with graphyne grown is placed in hydrochloric acid for ultrasonic treatment, filtered, washed, and dried to obtain a graphyne polymer; Step 2, preparation of oxidized graphene: placing the graphene polymer obtained in step 1 in a single-mouth bottle, adding a magnet, adding concentrated sulfuric acid dropwise under ice-water bath conditions, and then adding hydrogen peroxide dropwise, stirring for 5 minutes under ice-water bath, transferring it to room temperature and stirring for 1 hour, adding a large amount of deionized water after the reaction is completed to quench the reaction, and centrifuging and drying to obtain oxidized graphene; Step 3, preparation of oxidized carbon nanotubes: multi-walled carbon nanotubes are placed in a dry single-mouth bottle equipped with a condenser, 9M HNO3 is slowly added, and the mixture is refluxed at 75°C for 24h, and then filtered, washed and dried to obtain oxidized carbon nanotubes; Step 4, preparation of oxidized graphyne / oxidized carbon nanotube heterogeneous material: the oxidized graphyne obtained in step 2 and the oxidized carbon nanotubes obtained in step 3 are placed in a single-mouth bottle equipped with a magnet in a mass ratio of 3:7 and deionized water is added. After ultrasonic dispersion for 5 minutes, the mixture is stirred and condensed under reflux at 80°C for 24 hours to allow them to fully contact to obtain a heterogeneous structure.

2. The preparation method of a neuron-like structure anode material according to claim 1, characterized in that, In the step 1, the ratio of pyridine to copper sheets is 150 mL: 20 copper sheets with a size of 1 cm×5 cm.

3. The preparation method of a neuron-like structure anode material according to claim 1, characterized in that, The volume ratio of concentrated sulfuric acid to hydrogen peroxide in step 2 is 7:3.

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