Thiazole-connected covalent organic framework carbon nanomaterial compound as well as preparation method and application thereof

Abstract

The invention discloses a thiazole-linked covalent organic framework carbon nanomaterial compound as well as a preparation method and application thereof. The preparation method comprises the following steps: adding 4, 4 ', 4'-tetramethyl-4, 4 ', 4'-tetramethyl-4, 4 '-tetramethyl-4, 4'-tetramethyl-4, 4 '- 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) tribenzaldehyde, elemental sulfur and an amino-modified carbon nanomaterial in a solvent, reacting under the action of a catalyst, and purifying after the reaction to obtain the compound. The compound has high chemical stability, high crystallinity and excellent conductivity, and shows excellent rate capability and long cycle stability in a lithium ion battery. The invention provides a new thought for design and preparation of a high-performance energy storage electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to a thiazole-linked covalent organic framework carbon nanomaterial composite, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries are widely used as efficient energy storage devices in the fields of agriculture and food production. However, traditional anode materials (such as graphite) are difficult to meet the requirements of next-generation energy storage technologies due to their limited capacity and poor rate performance. Covalent organic frameworks (COFs) are considered potential candidates for next-generation energy storage materials due to their highly tunable chemical structures and excellent thermochemical stabilities. However, COFs generally suffer from insufficient conductivity and limited chemical stability, which restricts their application in high-performance energy storage electrodes.

[0003] In recent years, the composite of COFs with conductive materials (such as carbon nanotubes or graphene) has become an important strategy to improve their electrochemical performance. However, achieving uniform growth of COFs on conductive support materials still faces challenges. In addition, the imine bonds in traditional COFs have poor chemical stability and are easily decomposed in electrolytes, thereby affecting their cycle life. For example: CN 119092697 A synthesizes COFs through imine bond reactions and coats carbon nanotubes. However, imine bonds are easily decomposed in the presence of acid or base, affecting the cycle life of the material, and the range of available electrolytes is limited. At the same time, the electron transport ability of imine bond-linked COFs is inherently poor; this composite material only relies on π-π interactions and van der Waals forces to promote the binding between carbon nanotubes (CNT) and COFs, lacks covalent bond binding, and the interfacial binding force is relatively weak, which easily leads to interfacial detachment.

[0004] CN118206771A discloses that amino-functionalized carbon nanotubes and COF are connected by condensation of amino groups and aldehyde groups to form imine bonds. Although chemical bonding is introduced into the formed composite material, potassium hydroxide is selected as the catalyst, resulting in unstable imine bonds and decomposition during the reaction process.

[0005] CN113336961A discloses a preparation method of a sulfur-rich covalent organic framework with thiazole groups, which uses 1,3,5-tris(3-aminophenyl)benzene, vinyl-containing aromatic aldehyde, and sulfur powder as raw materials to obtain a sulfur-rich covalent organic framework with thiazole groups by a one-pot method. Although the stability of COFs is improved by generating thiazole bonds, its electron conduction ability is general and its electrochemical energy storage performance is poor. Even when compounded with conductive materials, the improvement of electrochemical energy storage performance is still limited.

[0006] Based on this, it is necessary to synergistically optimize the chemical stability and electron conduction ability of the COFs-conductive material interface and enhance the interfacial interaction to improve the electrochemical performance of the composite material. Summary of the Invention

[0007] The present invention provides a preparation method of a COF composite material for constructing a thiazole linkage through a one-step oxidation cyclization reaction. By introducing amino-modified carbon nanomaterials, the uniform growth of COF on the surface of CNT or graphene is promoted to form a composite material. In the present invention, the amino group on the carbon nanomaterial reacts with the aldehyde group to form an imine bond, and then a more stable thiazole bond is formed under the action of sulfur. And the thiazole bond has a higher degree of conjugation, which is more conducive to electron transfer, improving the conductivity of the material and its performance as an electrode material. This composite material not only has high chemical stability and excellent electrical conductivity, but also exhibits excellent rate performance and long cycle life in lithium-ion batteries.

[0008] A preparation method of a thiazole-linked covalent organic framework carbon nanomaterial composite, comprising 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 under the action of a catalyst, and purifying after the reaction to obtain the composite.

[0009] Among them, elemental sulfur is used as an oxidant to promote the one-step formation of a covalent organic framework linked by thiazole bonds, and at the same time promote the oxidation of the imine bond formed by the reaction of the amino group and the aldehyde group on the carbon nanomaterial into a more stable thiazole bond.

[0010] 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 are used as monomers. The monomer contains a triazine group, and the introduction of nitrogen atoms in the triazine group greatly improves the reaction activity of the composite as a negative electrode active material, thereby improving its electrochemical energy storage performance. In the experiment, some other monomers containing triphenylamine functional groups and tribenzaldehyde functional groups were tried to react, and the performance of the obtained covalent organic framework carbon nanomaterial composite was not as good as Figure 1 the product performance in

[0011] Preferably, the solvent is a mixture of dimethyl sulfoxide (DMSO), o-dichlorobenzene (o-DCB), and n-butanol, and the volume ratio is 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 addition amount of the amino-modified carbon nanotube 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 an amino-modified carbon nanomaterial is added to the solvent, and a uniform reaction system is formed by ultrasonic dispersion. 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 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 an amino-modified carbon nanomaterial are dissolved in a solvent, and then the mixture formed after adding a catalyst is placed in a liquid nitrogen bath for freezing, evacuated and sealed, and then an oxidative cyclization reaction is carried out at 120 °C. After the reaction is completed, the covalent organic framework carbon nanomaterial composite is obtained by purification. The reaction time is preferably 3-5 days.

[0017] A thiazole-linked covalent organic framework carbon nanomaterial composite, the composite comprising a carbon nanomaterial and a covalent organic framework coated on the surface of the carbon nanomaterial, and the covalent organic framework having a structural unit as shown below:

[0018]

[0019] The carbon nanomaterial and the covalent organic framework are bonded through a thiazole bond.

[0020] The thiazole-linked covalent organic framework carbon nanomaterial composite has 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 pore size distribution of the covalent organic framework carbon nanotube composite is 0.5-50 nm, and the specific surface area is 50-2000 m 2 / g.

[0023] Preferably, the covalent organic framework carbon nanotube composite exhibits excellent rate performance in lithium-ion batteries, and the discharge capacity is 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, and the negative electrode active material is the thiazole-linked covalent organic framework carbon nanomaterial composite described above or the 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 are not easily hydrolyzed in acidic or alkaline environments, improving the durability and cycle life of the material and broadening the range of electrolytes used;

[0027] 2. The carbon nanomaterial modified by amino groups forms a more stable thiazole bond with COF, enhancing the interfacial binding force, improving conductivity, and enhancing stability. Preferably, amino-functionalized CNT is used as a template and conductive support, enhancing the conductivity and mechanical strength of the composite material;

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

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

[0030] Figure 2 It is the PXRD pattern of the Thz-COF material of the present invention;

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

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

[0033] Figure 5 It is the charge-discharge performance graph of the Thz-COF@CNT composite used as the negative electrode active material at a current density of 1000 mA / g for 500 cycles. Specific Embodiment Methods

[0035] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0036] Example 1: Preparation of Thz-COF

[0037] Figure 1 It is a schematic diagram of the synthesis of Thz-COF material. Add 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) into a glass tube, add a mixed solvent of DMSO:o-DCB:n-butanol (volume ratio 6:19:95, 1 mL), and ultrasonically disperse for 5 minutes. After dropping an aqueous acetic acid solution (6 M, 0.10 mL), freeze the mixture in a liquid nitrogen bath and pump to vacuum to 0.5 mbar. Seal the glass tube and react in an oven at 120 °C for 4 days. Wash the product with THF and acetone, and extract in a Soxhlet extractor for 24 hours, and dry to obtain Thz-COF (yield 85%).

[0038] Figure 2 It is the powder X-ray diffraction pattern of Thz-COF. The results of the powder X-ray diffraction pattern of the newly synthesized sample show that the Thz-COF material has high crystallinity. After soaking the Thz-COF material in 1 M hydrochloric acid solution or 1 M sodium hydroxide solution for 1 week respectively, rinse with deionized water, dry at 100 °C for 12 hours, and weigh to find that there is almost no mass loss. Test its powder X-ray diffraction again, and the results show that the Thz-COF material still maintains its excellent crystallinity. It shows that it has excellent acid-base stability.

[0039] Figure 3 It is the scanning electron microscope image of the Thz-COF material, and the results show that its microscopic morphology is a dense micron aggregate formed by the aggregation of irregularly shaped nanoparticles.

[0040] Example 2: Preparation of Thz-COF@CNT

[0041] Add 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), amino-modified carbon nanotubes (8 mg) and elemental sulfur (40 mg) into a glass tube, add a mixed solvent of DMSO:o-DCB:n-butanol (volume ratio 6:19:95, 1 mL), and ultrasonically disperse for 5 minutes. After dropping an aqueous acetic acid solution (6 M, 0.10 mL), freeze the mixture in a liquid nitrogen bath and pump to vacuum to 0.5 mbar. Seal the glass tube and react in an oven at 120 °C for 4 days. Wash the product with THF and acetone, and extract in a Soxhlet extractor for 24 hours, and dry to obtain the Thz-COF@CNT composite (yield 90%).

[0042] Figure 4 It is the scanning electron microscope image of the Thz-COF@CNT composite material. The results show that its microscopic morphology is a porous and fluffy micron aggregate formed by the aggregation of strip-shaped nanoparticles. The pore size distribution of the Thz-COF@ composite is 0.5 - 50 nm, and the specific surface area is 50 - 2000 m 2 / g. The difference in the morphology from the Thz-COF material is due to the addition of amino-modified CNT as a template during synthesis, which guides the monomers to react on the surface of CNT and form a COF-coated structure.

[0043] Performance Test

[0044] Performance test of using Thz-COF@CNT as the anode active material of a lithium-ion battery: Mix Thz-COF@CNT, carbon black, and polytetrafluoroethylene in a mass ratio of 6:3:1, grind evenly, then add N-methylpyrrolidone for dispersion, add ball-milling beads to the obtained mixture and homogenize and stir for 12 h, and then evenly coat the obtained slurry onto the current collector and vacuum dry it in a vacuum oven at 60 °C for 12 h to obtain the lithium battery anode sheet. Thz-COF@CNT is loaded with approximately 1.1 mg / cm 2 . Assemble the prepared anode sheet, separator, and lithium sheet into a half-cell, and then test it on a constant current charge-discharge device. As Figure 5 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, showing excellent cycle stability.

Claims

1. A preparation method of a thiazole-linked covalent organic framework carbon nanomaterial composite, characterized in that, It includes the following steps: dissolving 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-aniline, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-benzaldehyde, elemental sulfur and amino-modified carbon nanomaterials in a solvent, reacting under the action of a catalyst, and purifying after the reaction to obtain a composite.

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

95.

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

4. The preparation method according to claim 1, characterized in that, The carbon nanomaterials are carbon nanotubes or graphene.

5. The preparation method according to claim 4, wherein The amino-modified carbon nanomaterials are amino-modified carbon nanotubes, and the addition amount of the amino-modified carbon nanotubes is 5-50% of the total mass of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-aniline and 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-benzaldehyde monomers.

6. The preparation method according to claim 1, wherein It includes the following steps: dissolving 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-aniline, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tri-benzaldehyde, elemental sulfur and amino-modified carbon nanomaterials in a solvent, freezing the mixture formed after adding the catalyst in a liquid nitrogen bath, vacuum-sealing, and then carrying out an oxidative cyclization reaction at 120 °C, and purifying after the reaction to obtain the covalent organic framework-carbon nanomaterial composite.

7. A thiazole-linked covalent organic framework carbon nanomaterial composite, characterized in that, The composite includes carbon nanomaterials and a covalent organic framework coated on the surface of the carbon nanomaterials, and the covalent organic framework has a structural unit as shown below: The carbon nanomaterials and the covalent organic framework are bonded through thiazole bonds.

8. The composite according to claim 7, wherein, The carbon nanomaterial is a carbon nanotube, the pore size distribution of the composite is 0.5 - 50 nm, and the specific surface area is 50 - 2000 m 2 / g.

9. The composite according to claim 7, wherein The carbon nanomaterials are carbon nanotubes, and the composite exhibits excellent rate performance in a lithium-ion battery, and the discharge capacity is 850 mAh / g at a current density of 1000 mA / g.

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

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