A thiazole-linked covalent organic framework carbon nanomaterial composite, and a preparation method and application thereof

Abstract

The application discloses a thiazole-connected covalent organic framework carbon nanomaterial composite and a preparation method and application thereof, and the preparation method comprises the following steps: dissolving 4,4',4''-(1,3,5-triazine-2,4,6-triyl) triphenylamine, 4,4',4''-(1,3,5-triazine-2,4,6-triyl) triphenyl aldehyde, elementary sulfur and amino-modified carbon nanomaterial in a solvent, and reacting under the action of a catalyst; and the composite is obtained after purification. The composite has high chemical stability, high crystallinity and excellent conductive performance, and exhibits excellent rate performance and long cycle stability in a lithium ion battery. The application provides a new idea for the design and preparation of high-performance energy storage electrode materials.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, specifically relating to a thiazole-linked covalent organic framework carbon nanomaterial composite, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in agriculture and food production as efficient energy storage devices. However, traditional anode materials (such as graphite) are insufficient in capacity and rate performance, making them unsuitable for next-generation energy storage technologies. Covalent organic frameworks (COFs) are considered potential candidates for next-generation energy storage materials due to their highly tunable chemical structure and excellent thermochemical stability. However, COFs generally suffer from insufficient conductivity and limited chemical stability, restricting their application in high-performance energy storage electrodes.

[0003] In recent years, combining COFs with conductive materials (such as carbon nanotubes or graphene) has become an important strategy for improving their electrochemical performance. However, achieving uniform growth of COFs on conductive support materials remains a challenge. Furthermore, the imine bonds in traditional COFs exhibit poor chemical stability and are prone to decomposition in electrolytes, thus affecting their cycle life. For example, CN 119092697 A synthesizes COFs and coats carbon nanotubes via an imine bond reaction. However, the imine bonds are easily decomposed under acidic or alkaline conditions, affecting the material's cycle life and limiting the range of usable electrolytes. Simultaneously, the electron transport capability of imine-bonded COFs is inherently poor; this composite material relies solely on π-π interactions and van der Waals forces to promote the bonding between carbon nanotubes (CNTs) and COFs, lacking covalent bonding, resulting in relatively weak interfacial adhesion and a tendency for interfacial detachment.

[0004] CN118206771A discloses an imine bond formed by the condensation of amino and aldehyde groups between aminated carbon nanotubes and COF. Although chemical bonding is introduced into the composite material, the use of potassium hydroxide as a catalyst makes the imine bond unstable and causes decomposition during the reaction.

[0005] CN113336961A describes a method for preparing thiazolium-based sulfur-rich covalent organic frameworks (COFs). Using 1,3,5-tris(3-aminophenyl)benzene, vinyl aromatic aldehydes, and sulfur powder as raw materials, a one-pot method is employed to synthesize thiazolium-based sulfur-rich COFs. While this method improves the stability of COFs by generating thiazolium bonds, their electronic conductivity is generally low, resulting in poor electrochemical energy storage performance. Even when combined with conductive materials, the improvement in electrochemical energy storage performance remains limited.

[0006] Therefore, it is necessary to synergistically optimize the chemical stability and electronic conductivity of the COFs-conductive material interface and enhance interfacial interactions to improve the electrochemical performance of the composite material. Summary of the Invention

[0007] This invention provides a method for preparing a COF composite material with thiazole linkages through a one-step oxidative cyclization reaction. By introducing amino-modified carbon nanomaterials, the uniform growth of COF on CNT or graphene surfaces is promoted, forming a composite material. In this invention, the amino groups on the carbon nanomaterials react with aldehyde groups to form imine bonds, which are then further enhanced by sulfur to form more stable thiazole linkages. Furthermore, the thiazole linkages exhibit higher conjugation, which is more conducive to electron transfer, improving the material's conductivity and its performance as an electrode material. This composite material not only possesses high chemical stability and excellent conductivity but also demonstrates excellent rate performance and long cycle life in lithium-ion batteries.

[0008] A method for preparing a thiazole-linked covalent organic framework carbon nanomaterial composite includes the following steps: dissolving 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, elemental sulfur, and amino-modified carbon nanomaterials in a solvent, reacting them under the action of a catalyst, and purifying the composite after the reaction is completed.

[0009] In this process, elemental sulfur acts as an oxidant, promoting the one-step formation of a covalent organic framework linked by thiazole bonds, while simultaneously oxidizing the imine bonds formed by the reaction of amino and aldehyde groups on carbon nanomaterials into more stable thiazole bonds.

[0010] Using 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde as monomers, the presence of triazine groups in the monomers significantly enhances the reactivity of the composite as a negative electrode material, thereby improving its electrochemical energy storage performance. Experiments have explored reactions with other monomers containing triphenylamine and tribenzaldehyde functional groups, but the resulting covalent organic framework carbon nanomaterial composites showed performance inferior to... Figure 1 The performance of the products in the process.

[0011] Preferably, the solvent is a mixture of dimethyl sulfoxide (DMSO), o-dichlorobenzene (o-DCB), and n-butanol in a volume ratio of 6:19:95.

[0012] Preferably, the catalyst is a 6M aqueous solution of glacial acetic acid.

[0013] For example, the carbon nanomaterial is a carbon nanotube or graphene. Preferably, the amino-modified carbon nanomaterial is an amino-modified carbon nanotube, and the amount of amino-modified carbon nanotube added is 5-50% of the total mass of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde monomers.

[0014] Preferably, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, and elemental sulfur are mixed in a solvent, and then amino-modified carbon nanomaterials are added to the solvent. The mixture is then dispersed by ultrasonication to form a homogeneous reaction system. More preferably, the reaction system is sealed under vacuum conditions.

[0015] Preferably, the purification includes washing the reaction product with tetrahydrofuran and acetone respectively, and extracting it in a Soxhlet extractor for 24 hours.

[0016] Preferably, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, elemental sulfur, and amino-modified carbon nanomaterials are dissolved in a solvent, and a catalyst is added. The resulting mixture is then frozen in a liquid nitrogen bath, sealed under vacuum, and subjected to an oxidative cyclization reaction at 120°C. After the reaction, the mixture is purified to obtain the covalent organic framework carbon nanomaterial composite. The reaction time is preferably 3-5 days.

[0017] A thiazole-linked covalent organic framework carbon nanomaterial composite, the composite comprising carbon nanomaterials and a covalent organic framework coated on the surface of the carbon nanomaterials, the covalent organic framework having the following structural units:

[0018]

[0019] The carbon nanomaterial and the covalent organic framework are linked by thiazole bonds.

[0020] The thiazole-linked covalent organic framework carbon nanomaterial composite exhibits high crystallinity and a porous structure.

[0021] When the carbon nanomaterial is preferably a carbon nanotube, the covalent organic framework carbon nanomaterial composite is a covalent organic framework carbon nanotube composite.

[0022] Preferably, the covalent organic framework carbon nanotube composite has a pore size distribution of 0.5-50 nm and a specific surface area of ​​50-2000 m². 2 / g.

[0023] Preferably, the covalent organic framework carbon nanotube composite exhibits excellent rate performance in lithium-ion batteries, with a discharge capacity of 850 mAh / g at a current density of 1000 mA / g.

[0024] A lithium-ion battery, characterized in that it includes a negative electrode active material, wherein the negative electrode active material is the thiazole-linked covalent organic framework carbon nanomaterial composite described above or a thiazole-linked covalent organic framework carbon nanomaterial composite prepared by the preparation method described above.

[0025] Compared with the prior art, the advantages of the present invention include:

[0026] 1. The introduction of thiazole bonds significantly improves the chemical stability of COF: Compared with imine bonds, thiazole bonds are more stable and less prone to hydrolysis in acidic or alkaline environments, thus improving the durability and cycle life of the material and broadening the range of electrolytes that can be used.

[0027] 2. Amino-modified carbon nanomaterials form more stable thiazole bonds with COF, enhancing interfacial bonding, improving conductivity, and increasing stability. Amino-modified CNTs are preferred as templates and conductive supports, further enhancing the conductivity and mechanical strength of the composite material.

[0028] 3. The one-step synthesis process is simple and efficient, and is suitable for large-scale production. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the synthesis of the Thz-COF material of the present invention;

[0030] Figure 2 The PXRD spectrum of the Thz-COF material of this invention;

[0031] Figure 3 This is a scanning electron microscope image of the Thz-COF material of the present invention;

[0032] Figure 4 This is a scanning electron microscope image of the Thz-COF@CNT composite material of the present invention;

[0033] Figure 5 The graph shows the charge-discharge performance of the Thz-COF@CNT composite of the present invention as a negative electrode active material after 500 cycles at a current density of 1000 mA / g. Specific implementation methods

[0034] The present invention will be further described below with reference to specific embodiments. These embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0035] Example 1: Preparation of Thz-COF

[0036] Figure 1 This is a schematic diagram of the synthesis of Thz-COF material. 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (20 mg), 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (20 mg), and elemental sulfur (40 mg) were added to a glass tube. A mixed solvent of DMSO:o-DCB:n-butanol (volume ratio 6:19:95, 1 mL) was added, and the mixture was ultrasonically dispersed for 5 minutes. After adding dropwise glacial acetic acid aqueous solution (6 M, 0.10 mL), the mixture was placed in a liquid nitrogen bath and evacuated to 0.5 mbar using a pump. The glass tube was sealed, and the reaction was carried out in an oven at 120 °C for 4 days. The product was washed with THF and acetone, extracted in a Soxhlet extractor for 24 hours, and dried to obtain Thz-COF (yield 85%).

[0037] Figure 2 This is the powder X-ray diffraction pattern of Thz-COF. The powder X-ray diffraction results of the newly synthesized sample show that Thz-COF material has high crystallinity. After soaking Thz-COF material in 1M hydrochloric acid solution or 1M sodium hydroxide solution for one week, rinsing with deionized water, and drying at 100℃ for 12 hours, almost no mass loss was found upon weighing. Further powder X-ray diffraction tests showed that Thz-COF material still maintains its excellent crystallinity, indicating its excellent acid and alkali stability.

[0038] Figure 3 These are scanning electron microscope images of Thz-COF materials, showing that their microstructure consists of dense micron-sized aggregates of irregularly shaped nanoparticles.

[0039] Example 2: Preparation of Thz-COF@CNT

[0040] 20 mg of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 20 mg of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, 8 mg of amino-modified carbon nanotubes, and 40 mg of elemental sulfur were added to a glass tube. A mixed solvent of DMSO:o-DCB:n-butanol (volume ratio 6:19:95, 1 mL) was added, and the mixture was ultrasonically dispersed for 5 minutes. After adding 0.10 mL of glacial acetic acid aqueous solution (6 M), the mixture was placed in a liquid nitrogen bath and evacuated to 0.5 mbar using a pump. The glass tube was sealed, and the reaction was carried out in an oven at 120 °C for 4 days. The product was washed with THF and acetone, extracted in a Soxhlet extractor for 24 hours, and dried to obtain the Thz-COF@CNT complex (yield 90%).

[0041] Figure 4 These are scanning electron microscope (SEM) images of the Thz-COF@CNT composite material. The results show that its microstructure consists of porous, fluffy micron-sized aggregates composed of strip-shaped nanoparticles. The pore size distribution of the Thz-COF@ composite is 0.5-50 nm, and its specific surface area is 50-2000 m². 2 The morphology differs from that of the Thz-COF material because amino-modified CNTs were added as templates during synthesis to guide the monomers to react on the CNT surface and form a COF-coated structure.

[0042] Performance testing

[0043] Performance testing of Thz-COF@CNT as a negative electrode active material for lithium-ion batteries: Thz-COF@CNT, carbon black, and polytetrafluoroethylene were mixed at a mass ratio of 6:3:1 and ground uniformly. Then, N-methylpyrrolidone was added for dispersion. Ball milling beads were added to the resulting mixture, and the mixture was stirred for 12 hours. The resulting slurry was then uniformly coated onto a current collector and vacuum dried in a vacuum oven at 60°C for 12 hours to obtain the lithium-ion battery negative electrode sheet. The Thz-COF@CNT loading was approximately 1.1 mg / cm³. 2 The prepared negative electrode, separator, and lithium sheet were assembled into a half-cell, and then tested on a constant current charge-discharge device. Figure 5 As shown, the discharge capacity is 850 mAh / g at a current density of 1000 mA / g, and the discharge capacity is 770 mAh / g after 500 cycles, demonstrating excellent cycle stability.

Claims

1. A method for preparing a thiazole-linked covalent organic framework carbon nanomaterial composite, characterized in that, The process includes the following steps: dissolving 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, elemental sulfur, and amino-modified carbon nanomaterials in a solvent, reacting them under the action of a catalyst, and purifying the mixture after the reaction is complete to obtain the complex.

2. The preparation method according to claim 1, characterized in that, The solvent is a mixture of dimethyl sulfoxide, o-dichlorobenzene and n-butanol in a volume ratio of 6:19:

95.

3. The preparation method according to claim 1, characterized in that, The catalyst is a 6M aqueous solution of glacial acetic acid.

4. The preparation method according to claim 1, characterized in that, The carbon nanomaterial is either carbon nanotube or graphene.

5. The preparation method according to claim 4, characterized in that, The amino-modified carbon nanomaterial is an amino-modified carbon nanotube, and the amount of amino-modified carbon nanotube added is 5-50% of the total mass of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde monomers.

6. The preparation method according to claim 1, characterized in that, The process includes the following steps: dissolving 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde, elemental sulfur, and amino-modified carbon nanomaterials in a solvent, adding a catalyst, freezing the resulting mixture in a liquid nitrogen bath, sealing it under vacuum, and then carrying out an oxidative cyclization reaction at 120°C. After the reaction is completed, the mixture is purified to obtain the covalent organic framework carbon nanomaterial composite.

7. A thiazole-linked covalent organic framework carbon nanomaterial composite, characterized in that, The composite comprises carbon nanomaterials and a covalent organic framework coated on the surface of the carbon nanomaterials, the covalent organic framework having the structural units shown below: The carbon nanomaterial and the covalent organic framework are linked by thiazole bonds.

8. The complex according to claim 7, characterized in that, The carbon nanomaterial is carbon nanotube, and the composite has a pore size distribution of 0.5-50 nm and a specific surface area of ​​50-2000 m². 2 / g.

9. The complex according to claim 7, characterized in that, The carbon nanomaterial is carbon nanotube, and the composite is used in lithium-ion batteries to achieve a discharge capacity of 850 mAh / g at a current density of 1000 mA / g.

10. A lithium-ion battery, characterized in that, The negative electrode active material is a thiazole-linked covalent organic framework carbon nanomaterial composite as described in any one of claims 7-9, or a thiazole-linked covalent organic framework carbon nanomaterial composite prepared by the preparation method described in any one of claims 1-6.

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