A covalent organic framework coating for a sodium metal battery and a method of making the same

Abstract

The application provides a kind of covalent organic framework coating for sodium metal battery and its preparation method, belong to sodium metal battery interface material technical field.The covalent organic framework coating includes covalent organic framework material, and is connected with each other after forming imine bond by Schiff base reaction dehydration condensation from three connecting point structure units and two connecting point structure units;Each connecting point of each two connecting point structure unit is connected with the connecting point of three connecting point structure unit;The three connecting point structure unit is 2,4,6-tri (4-aminophenyl) -1,3,5-triazine;The two connecting point structure unit is 2,3,5,6-tetrafluoro-p-benzaldehyde.The covalent organic framework material prepared by the application can effectively inhibit side reaction and electron tunneling as an effective passivation coating, ensure the interface stability, thereby improve the coulomb efficiency of sodium metal battery, alleviate the risk of rapid capacity decay and the thermal runaway caused.

Description

Technical Field

[0001] This invention belongs to the field of interface materials technology for sodium metal batteries, specifically relating to a covalent organic framework coating for sodium metal batteries and its preparation method. Background Technology

[0002] Sodium metal anodes have extremely high theoretical specific capacity (1166 mAh g). -1 With its low redox potential (-2.71 V vs. standard hydrogen electrode), it is considered an ideal choice to replace the traditional intercalation-type negative electrode and significantly improve the energy density of sodium batteries.

[0003] Sodium metal exhibits extremely high chemical reactivity, spontaneously forming a solid electrolyte interphase (SEI) film at the interface upon contact with organic liquid electrolytes. This electrolyte-derived natural SEI film exhibits highly uneven composition and structure, insufficient mechanical strength, and difficulty in achieving uniform sodium ion flux. Uneven electroplating / deposition exacerbates SEI film fragmentation and dendrite growth, ultimately leading to a significant reduction in coulombic efficiency, rapid capacity decay, and even the risk of thermal runaway.

[0004] In contrast, organic polymer materials are gaining increasing attention due to their advantages such as tunable elemental composition, highly designable molecular structure, flexible framework, and environmental friendliness. Organic polymers allow for precise control of the main chain structure and functional groups through molecular engineering, thereby enabling effective regulation of sodium storage potential, specific capacity, and reaction kinetics. Simultaneously, their flexible structure helps mitigate volume changes during sodium ion insertion or extraction, improving cycle stability.

[0005] However, existing organic polymer anode materials still suffer from the problem of some materials being easily soluble in electrolytes, leading to structural damage. Therefore, new organic polymer structures need to be designed to address the low cycle life of batteries caused by the dissolution of anode materials in electrolytes. For example, invention patent CN111944129A discloses a high-performance sodium battery anode organic polymer material, polymer PTSA, which is obtained by oxidative coupling reaction of 2,4,6-tris(2-thienyl)-1,3,5-triazine (TSA) in the presence of ferric chloride. Another example is invention patent CN121914399A, which discloses an organic polymer anode material, its preparation method, and its application in sodium-ion batteries. The monomer of this organic polymer anode material is formed by covalently linking a quinone skeleton with a nitrogen-containing heteroaromatic ring.

[0006] In addition, pre-constructing a functionalized protective coating on the surface of the sodium metal anode to replace or optimize the unstable natural SEI film is an effective strategy to solve the above problems. However, existing technologies generally suffer from complex preparation processes, unstable structures, insufficient sodium affinity, and low ionic conductivity. Therefore, designing an interface material that combines rapid ion conduction and mechanical stability, and developing a simple composite interface construction method are key to overcoming the performance bottleneck of sodium metal batteries. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a covalent organic framework coating for sodium metal batteries and its preparation method. The covalent organic framework material serves as an effective passivation coating to replace or optimize the unstable natural SEI film, effectively suppressing side reactions and electron tunneling, ensuring interface stability, thereby improving the coulombic efficiency of sodium metal batteries and mitigating the risk of rapid battery capacity decay and thermal runaway.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a covalent organic framework coating for sodium metal batteries. The organic framework material of the covalent organic framework coating is formed by the dehydration condensation of three-connection-point structural units and two-connection-point structural units through a Schiff base reaction to form imine bonds, which are then interconnected. Each connection point of each two-connection-point structural unit is connected to a connection point of a three-connection-point structural unit. The three-connection-point structural unit is 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, with the corresponding structural formula being [structural formula would be inserted here]. The two-connection-point structural unit is 2,3,5,6-tetrafluoro-p-dibenzaldehyde, with the corresponding structural formula being... .

[0009] Based on 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,3,5,6-tetrafluoro-p-dibenzaldehyde, a highly crystalline covalent organic framework material rich in nitrogen and fluorine atoms was prepared by means of a Schiff base reaction, in which an amino group (–NH2) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine reacts with an aldehyde group (=O) of 2,3,5,6-tetrafluoro-p-dibenzaldehyde to remove a water molecule and generate an imine bond.

[0010] More preferably, the chemical structural formula of the organic framework material is shown below: The dashed lines indicate that the orientation of the structure extends along the plane of the paper.

[0011] The covalent organic framework coating material provided by this invention has abundant electronegative nitrogen / fluorine atoms, forming "Na" at the coating / electrolyte interface. +"Capture-transfer" sites promote Na + Desolvation and induction of homogeneous Na + Flux, inhibiting dendrite growth; the regular nanopores inside the covalent organic framework material are Na + The transport mechanism provides a fast transport path, accelerating mass transfer kinetics; the covalent organic framework material acts as an effective passivation coating, effectively suppressing side reactions and electron tunneling, and ensuring interface stability.

[0012] Preferably, the method for preparing the covalent organic framework material includes: mixing 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,3,5,6-tetrafluoro-p-dibenzaldehyde, a protic acid catalyst, and an organic solvent, and then carrying out a solvothermal reaction to obtain the covalent organic framework material.

[0013] This invention involves a solvothermal reaction of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,3,5,6-tetrafluoro-p-dibenzaldehyde under a protic acid catalyst. This reaction allows the amino group in 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to form a covalently linked carbon-nitrogen double bond with the aldehyde group in 2,3,5,6-tetrafluoro-p-dibenzaldehyde, ensuring the preparation of a highly crystalline covalent organic framework material rich in nitrogen and fluorine atoms.

[0014] Preferably, the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,3,5,6-tetrafluoro-p-dibenzaldehyde is 2:(2.5~3.5).

[0015] This invention ensures precise matching of the reaction sites of the amino and aldehyde groups by limiting the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to 2,3,5,6-tetrafluoro-p-dibenzaldehyde, avoiding unreacted end groups and forming a highly cross-linked, defect-free rigid framework; it also maximizes the crystallinity, porosity, and specific surface area of ​​the covalent organic framework material, providing Na... + The transmission provides ample space.

[0016] Preferably, the protic acid catalyst is an aqueous solution of acetic acid, wherein the concentration of acetic acid in the aqueous solution is 3-9 mol / L. -1 .

[0017] Protic acid catalysts promote the efficient condensation of imine bonds by activating carbonyl groups and utilize their weak acid properties to regulate the reversible breaking and recombination process of dynamic covalent bonds, endowing the reaction system with the necessary self-repairing ability and ensuring that the product has high crystallinity and a regular and ordered nanoporous structure.

[0018] More preferably, the volume ratio of the protic acid catalyst to the molar amount of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is (0.5~1.5) mL:1 mmol.

[0019] Preferably, the organic solvent is one or more of o-dichlorobenzene, n-butanol, mesitylene, and dioxane.

[0020] More preferably, the organic solvent is o-dichlorobenzene and n-butanol, with a volume ratio of 1:1.

[0021] Preferably, the temperature of the solvothermal reaction is 100℃~180℃; the time of the solvothermal reaction is 12~100 h.

[0022] In a solvothermal reaction, the amino group in 2,4,6-tris(4-aminophenyl)-1,3,5-triazine reacts with the aldehyde group in 2,3,5,6-tetrafluoro-p-dibenzaldehyde to form a carbon-nitrogen double bond. By limiting the temperature and time of the solvothermal reaction, the reaction of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,3,5,6-tetrafluoro-p-dibenzaldehyde under the catalysis of a protic acid catalyst is ensured to be complete, thus preparing a highly crystalline covalent organic framework material.

[0023] Furthermore, the solvothermal reaction is carried out under vacuum conditions.

[0024] Preferably, after the solvothermal reaction, the covalent organic framework material is obtained by sequentially undergoing solid-liquid separation, washing, purification, and drying.

[0025] Furthermore, the solid-liquid separation method is vacuum filtration.

[0026] Further, the sample was washed sequentially with dichloromethane and anhydrous ethanol.

[0027] Further purification was performed using Soxhlet extraction with tetrahydrofuran as the solvent; the extraction temperature was 100℃~150℃; and the extraction time was 12~72 h.

[0028] Furthermore, the drying method is vacuum drying, the temperature of which can be 80℃~120℃, and the time of which can be 12~24 h.

[0029] Preferably, the preparation method of the covalent organic framework material specifically includes: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,3,5,6-tetrafluoro-p-dibenzaldehyde were respectively mixed with organic solvents to obtain a first mixture and a second mixture; The first mixture and the second mixture are mixed to obtain the third mixture, and then a protic acid catalyst is added and mixed to obtain the fourth mixture; The fourth mixture undergoes a solvothermal reaction, followed by solid-liquid separation, washing, purification, and drying to obtain a covalent organic framework material.

[0030] Furthermore, the mixing was performed under ultrasound for 5–15 minutes.

[0031] Furthermore, the mixing is carried out in a Pyrex tube. After mixing, the Pyrex tube is sequentially subjected to freezing-degassing-thawing and sealing. This invention does not impose any particular limitations on the freezing-degassing-thawing and sealing processes; any freezing-degassing-thawing and sealing methods well-known in the art can be used to ensure a vacuum environment in the Pyrex tube.

[0032] On the other hand, the present invention also provides a method for preparing a covalent organic framework coating for sodium metal batteries, the steps of which include: drying the covalent organic framework material and dispersing it on the surface of a sodium metal foil, and forming a covalent organic framework coating by calendering.

[0033] Furthermore, the drying process utilizes a vacuum drying oven or a forced-air drying oven.

[0034] Preferably, the drying temperature is 90℃~120℃; the drying time is 6~24 h.

[0035] This invention removes water adsorbed by covalent organic framework materials by controlling the drying temperature and drying time, thus avoiding side reactions with sodium metal during subsequent preparation processes.

[0036] Preferably, the loading of the covalent organic framework material is 0.1~2 mg cm⁻¹. -2 .

[0037] Preferably, the thickness of the sodium metal foil is 0.1~0.6 mm.

[0038] Preferably, the rolling temperature of the calendered coating is 15℃~40℃; the roll gap is 50~500 μm; and the rolling speed is 0.5~5 cm / s. -1 .

[0039] This invention ensures a strong bond between the covalent organic framework material and the sodium metal foil surface by limiting the loading of the covalent organic framework material and the rolling parameters of the calendered coating, thereby further ensuring the stability of the covalent organic framework coating.

[0040] Compared with the prior art, the present invention has the following beneficial effects: (1) The covalent organic framework material provided by this invention has abundant electronegative nitrogen / fluorine atoms, forming "Na" at the coating / electrolyte interface. + "Capture-transfer" sites promote Na +Desolvation and induction of homogeneous Na + Flux, inhibiting dendrite growth; the regular nanopores inside the covalent organic framework material are Na + Transport provides a fast transport path, accelerating mass transfer dynamics.

[0041] (2) Covalent organic framework coatings prepared based on covalent organic framework materials have significant passivation effects, which can effectively suppress side reactions and electron tunneling and ensure interface stability. When applied in sodium metal batteries, sodium metal batteries have high rate performance and good cycle stability.

[0042] (3) The preparation method of the covalent organic framework coating provided by the present invention is simple and has low energy consumption, which is conducive to large-scale production. Attached Figure Description

[0043] Figure 1 The structural formula of the covalent organic framework material provided by this invention.

[0044] Figure 2 This is a scanning electron microscope (SEM) image of the covalent organic framework material prepared in Example 1 of the present invention, magnified 50,000 times.

[0045] Figure 3 This is a SEM image of the covalent organic framework material prepared in Example 2 of the present invention, magnified 50,000 times.

[0046] Figure 4 This is a SEM image of the covalent organic framework material prepared in Example 3 of the present invention, magnified 50,000 times.

[0047] Figure 5 The X-ray diffraction (XRD) pattern and refined image of the covalent organic framework material prepared in Example 1 of this invention.

[0048] Figure 6 XRD pattern of the covalent organic framework material prepared in Example 2 of this invention.

[0049] Figure 7 XRD pattern of the covalent organic framework material prepared in Example 3 of this invention.

[0050] Figure 8 The image shows a 2000x magnified SEM image of the covalent organic framework composite negative electrode prepared in Example 1 of this invention.

[0051] Figure 9 The graph shows the rate performance of the symmetrical battery of the covalent organic framework composite anode prepared in Example 1 of this invention and the sodium metal anode prepared in Comparative Example 1.

[0052] Figure 10The covalent organic framework composite anode prepared in Example 1 of this invention and the sodium metal anode prepared in Comparative Example 1 were compared at 0.5 mA cm⁻¹. -2 Current density and 1 mAh cm -2 Cyclic stability performance of a symmetrical battery at a given capacity.

[0053] Figure 11 The covalent organic framework composite anode prepared in Example 1 of this invention and the sodium metal anode prepared in Comparative Example 1 were compared at 1 mA cm⁻¹. -2 Current density and 1 mAh cm -2 Cyclic stability performance of a symmetrical battery at a given capacity.

[0054] Figure 12 The rate performance diagrams show the full cells assembled with Na3V2(PO4)3 positive electrodes using the covalent organic framework composite negative electrode prepared in Example 1 and the sodium metal negative electrode prepared in Comparative Example 1.

[0055] Figure 13 The graphs show the 5C rate cycling performance of the covalent organic framework composite anode prepared in Example 1 of this invention and the sodium metal anode prepared in Comparative Example 1, respectively, assembled with Na3V2(PO4)3 cathode to form a full cell.

[0056] Figure 14 The graphs show the 10 C rate cycling performance of the covalent organic framework composite anode prepared in Example 1 of this invention and the sodium metal anode prepared in Comparative Example 1, respectively, assembled with Na3V2(PO4)3 cathode to form a full cell. Detailed Implementation

[0057] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the invention, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0058] All raw materials are sourced from the market.

[0059] Example 1 A covalent organic framework coating for sodium metal batteries, comprising a covalent organic framework material, with a specific structural formula as follows: Figure 1 As shown, denoted as TFTA-TAPT COF, the preparation process specifically includes: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (0.2 mmol), o-dichlorobenzene (0.75 mL), and n-butanol (0.75 mL) were placed in a Pyrex tube and ultrasonically dispersed for 10 min. 2,3,5,6-Tetrafluoro-p-dibenzaldehyde (0.3 mmol), o-dichlorobenzene (0.75 mL), and n-butanol (0.75 mL) were placed in a Pyrex tube and ultrasonically dispersed for 10 min. The two mixtures were transferred to Pyrex tubes, ultrasonically dispersed for 10 min, and then 6 mol L⁻¹ was added. -1 Add 0.2 mL of acetic acid aqueous solution and sonicate for another 10 min; The Pyrex tube containing the mixture was frozen in liquid nitrogen and evacuated for 15 minutes using a vacuum pump. Nitrogen gas was then introduced and the tube was thawed. After repeating the freezing-degassing-thawing process three times, the Pyrex tube was sealed with a flame under vacuum. After thawing, the sealed Pyrex tube was placed in a forced-air drying oven and kept at 120°C for 72 hours. After natural cooling, the solid product in the Pyrex tube was removed and washed with dichloromethane and anhydrous ethanol, respectively. The product was then subjected to Soxhlet extraction with tetrahydrofuran at 110°C for 24 hours. The Soxhlet extracted product was placed in a vacuum drying oven and dried under vacuum at 100°C for 24 hours to obtain the orange-yellow covalent organic framework material powder TFTA-TAPT COF.

[0060] The molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to 2,3,5,6-tetrafluoro-p-dibenzaldehyde is 2:3; the volume ratio of the acetic acid aqueous solution to the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is 1 mL:1 mmol; and the volume ratio of o-dichlorobenzene to n-butanol is 1:1.

[0061] The prepared covalent organic framework material was dispersed on a 0.3 mm thick sodium metal foil in an argon glove box with a loading of 0.2 mg cm⁻¹. -2 A composite negative electrode, denoted as COF@Na, was prepared by calendering and coating. The rolling temperature for calendering and coating was 28℃, the roll gap was 300 μm, and the rolling speed was 1 cm / s. -1 .

[0062] Example 2 A covalent organic framework coating for sodium metal batteries differs from Example 1 in that the amount of 2,3,5,6-tetrafluoro-p-dibenzaldehyde used is 0.25 mmol; and the amount of acetic acid aqueous solution used is 9 mol L. -1(0.1 mL); the solvothermal reaction temperature used was 180℃; the solvothermal reaction time used was 12 h.

[0063] Example 3 A covalent organic framework coating for sodium metal batteries differs from Example 1 in that the amount of 2,3,5,6-tetrafluoro-p-dibenzaldehyde used is 0.35 mmol; and the amount of acetic acid aqueous solution used is 3 mol / L. -1 (0.3 mL); the solvothermal reaction temperature used was 100℃; the solvothermal reaction time used was 100 h.

[0064] Comparative Example 1 The preparation process of this comparative example is the same as that of Example 1, except that: sodium metal foil is used as the negative electrode and no coating material is used, denoted as Bare Na.

[0065] Product characteristics: The morphology of the covalent organic framework materials prepared in Examples 1, 2, and 3 was characterized using scanning electron microscopy, and the results are as follows: Figures 2-4 As shown, this is a cluster of nanoparticles with a particle size of approximately 100 nm.

[0066] The crystallinity of the covalent organic framework materials prepared in Examples 1, 2, and 3 was characterized using X-ray diffraction, and the results are as follows: Figures 5-7 As shown. Structural refinement using crystal structure modeling reveals that the peaks at 2θ = 2.95°, 5.73°, and 7.56° of the covalent organic framework material prepared in Example 1 belong to the (100), (200), and (210) crystal planes, respectively, demonstrating good crystallinity. Furthermore, its weighted residual variance factor and residual variance factor are 2.23% and 1.56%, respectively, proving that the crystal structure of the covalent organic framework material prepared in Example 1 matches the crystal structure of the established model, indicating a two-dimensional covalent organic framework structure. Figure 6 , Figure 7 As shown, the XRD patterns of the covalent organic framework materials prepared in Examples 2 and 3 are similar to those in Example 1, proving that Examples 2 and 3 are two-dimensional covalent organic framework structures. The morphology of the sodium metal composite anode prepared in Example 1 was characterized using scanning electron microscopy, and the results are as follows: Figure 8 As shown, the covalent organic framework material is uniformly embedded on the surface of the sodium metal foil, indicating the uniformity of the covalent organic framework coating.

[0067] The negative electrodes of Example 1 and Comparative Example 1 were placed in an argon glove box with water and oxygen contents both less than 0.01 ppm. Sodium metal symmetric cells and full cells were assembled using an EC / DEC solution (volume ratio 1:1) containing 5% fluoroethylene carbonate and 1.0 M NaClO4 as the electrolyte and a glass fiber separator. The positive and negative electrodes of the symmetric cells were identical, while the full cell used Na3V2(PO4)3 as the positive electrode.

[0068] The batteries prepared in Example 1 and Comparative Example 1 were tested for rate performance and cycle performance using the LAND battery testing system. The results are as follows: Figures 9-14 As shown. By Figure 9 and Figure 12 It can be seen that the symmetrical cell and the full cell of Example 1 have significantly better rate performance; from Figure 10 and Figure 11 It can be seen that the symmetrical cell of Example 1 is at 0.5 mA cm⁻¹ -2 and 1 mAcm -2 At current densities of [specific values], they can cycle 2000 and 900 times respectively, far exceeding that of Comparative Example 1; [The text abruptly ends here, likely due to an incomplete translation or a missing section.] Figure 13 and Figure 14 It can be seen that the full cell of Example 1 can cycle 6000 and 7000 times at current densities of 5 C and 10 C, respectively, which is much longer than that of Comparative Example 1; in addition, the full cell of Example 1 can achieve 108.5 mAh g⁻¹ at current densities of 5 C and 10 C, respectively. -1 and 107.4 mAhg -1 The discharge specific capacity and capacity retention rates of 87% and 86% of the sample are both higher than those of Comparative Example 1. Therefore, the sodium metal battery prepared in Example 1 of this invention exhibits better performance.

[0069] In summary, the sodium metal battery assembled with a composite negative electrode made of a covalent organic framework layer containing covalent organic framework material provided by the present invention has high discharge specific capacity, good cycle stability, and good rate performance.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A covalent organic framework coating for sodium metal batteries, comprising a covalent organic framework material, characterized in that, The covalent organic framework material is formed by the dehydration condensation of three-connection-point structural units and two-connection-point structural units through a Schiff base reaction to form imine bonds, which are then interconnected; each connection point of each two-connection-point structural unit is connected to a connection point of a three-connection-point structural unit. The three-connection-point structural unit is 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; the two-connection-point structural unit is 2,3,5,6-tetrafluoro-p-dibenzaldehyde.

2. The covalent organic framework coating for sodium metal batteries according to claim 1, characterized in that, The chemical structural formula of the covalent organic framework material is shown below: 。 3. The covalent organic framework coating for sodium metal batteries according to claim 1 or 2, characterized in that, The method for preparing the covalent organic framework material includes: mixing 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,3,5,6-tetrafluoro-p-dibenzaldehyde, a protic acid catalyst, and an organic solvent, and then carrying out a solvothermal reaction to obtain the covalent organic framework material.

4. The covalent organic framework coating for sodium metal batteries according to claim 3, characterized in that, The molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to 2,3,5,6-tetrafluoro-p-dibenzaldehyde is 2:(2.5~3.5).

5. The covalent organic framework coating for sodium metal batteries according to claim 3, characterized in that, The protic acid catalyst is an aqueous solution of acetic acid, wherein the concentration of acetic acid in the aqueous solution is 3-9 mol / L. -1 .

6. The covalent organic framework coating for sodium metal batteries according to claim 5, characterized in that, The volume ratio of the protic acid catalyst to the molar amount of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is (0.5~1.5) mL:1 mmol.

7. The covalent organic framework coating for sodium metal batteries according to claim 3, characterized in that, The temperature for the solvothermal reaction is 100℃~180℃; The solvothermal reaction time is 12~100 h.

8. The method for preparing a covalent organic framework coating for sodium metal batteries according to any one of claims 1-7, characterized in that, step... include: The covalent organic framework material is dried and dispersed on the surface of sodium metal foil, and a covalent organic framework coating is formed by calendering.

9. The preparation method according to claim 8, characterized in that, The loading capacity of covalent organic framework materials is 1~10 mgcm³. -2 .

10. The preparation method according to claim 8, characterized in that, The rolling temperature of the calendered coating is 15℃~40℃; The roller gap is 50~500 μm; The roller pressing speed is 0.5~5 cm / s. -1 .

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