Preparation method of one-pot ionized imine covalent organic framework material and application thereof

Abstract

This paper presents a one-pot method for preparing imine-based covalent organic framework materials (iCOFs) and their applications, belonging to the field of porous material synthesis and functionalization technology. The method involves mixing an amino monomer with an aldehyde monomer containing sodium bisulfite and aniline as a modifier, and then conducting a one-pot reaction under acidic catalysis. Utilizing the in-situ nucleophilic addition of sodium bisulfite to the imine bond, a uniform introduction of sulfonate anions into the covalent organic framework is achieved in one step, preserving crystallinity and pore structure while reducing costs. The resulting iCOFs are then composited with carboxylated cellulose nanofibers to prepare a solid-state sodium-ion battery separator. The dense anion distribution within the framework effectively restricts anion movement and inhibits sodium dendrite growth, endowing the battery with high discharge specific capacity, low interfacial impedance, and long-term cycle stability exceeding 1500 hours, demonstrating broad application prospects in the field of solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of porous material synthesis and functionalization technology, and relates to a one-pot method for ionizing imine covalent organic frameworks by in-situ addition of imine bonds with sodium bisulfite and its application. Specifically, it relates to a one-pot synthesis method of ionic covalent organic framework materials (iCOFs) and its application in solid-state battery separators. Background Technology

[0002] Covalent organic frameworks (COFs) are crystalline porous organic materials linked by covalent bonds. In 2005, Yaghi pioneered the reporting of COFs. Today, these materials have attracted widespread attention and made significant progress in many fields, including separation, catalysis, energy storage, adsorption, sensors, and life sciences, due to their advantages such as crystallinity, regular pore structure, stable framework, and precisely designable structure. Since crystalline materials require reversible, mild conditions for self-repair, existing COFs exhibit diverse bonding modes. Among them, imine-linked COFs, compared to most other types of COFs, demonstrate suitable reversibility, relative stability in aqueous solutions, large specific surface area, high porosity, ease of functionalization, and strong structural designability. They are currently the most widely studied type of COF, and continuous innovation is being made based on their imine bond structure.

[0003] With the further development of research on COFs, ionic covalent organic frameworks (iCOFs) have emerged to meet the growing needs of fields such as energy. Ionic covalent organic frameworks inherit the crystallinity, porosity, and structural designability of traditional COFs, while also possessing ionic compound properties not found in traditional COFs, such as proton transport and ion conduction. This gives them greater potential in popular fields such as sensing, molecular detection, adsorption and separation, and rechargeable batteries. iCOFs are divided into cationic and anionic types. Cationic COFs consist of a positive ionic framework modified at nodes, the main chain, or side chains, and exchangeable counterions. Anionic COFs can also be achieved through modifications at these positions, typically using modifying monomers for direct synthesis or by modifying the reactive groups of the COFs after synthesis.

[0004] The preparation of ionic covalent organic frameworks (iCOFs) can be divided into two strategies: direct synthesis and post-modification. Currently, direct synthesis is the most common method for constructing iCOFs, using ionic monomers to react with other neutral monomers to assemble various topological structures. As the most widely used method for synthesizing ionic covalent organic frameworks, the solvothermal method usually requires careful selection of appropriate solvent ratios and catalyst dosages to achieve the direct preparation of highly crystalline iCOFs. Based on current research, most reports on ionic covalent organic framework materials focus on applications such as water treatment, heterogeneous catalysis, sensing, and proton conduction. However, exploration in the field of high-energy-density solid-state metal battery separators or electrolytes is still in its early stages, with many issues related to safety and ion migration efficiency. Therefore, developing an iCOF battery separator that achieves high conductivity and ion transference number without generating solid-liquid interface side reactions, thus ensuring battery performance and lifespan, is of significant practical value. Summary of the Invention

[0005] To address the above technical problems, this invention selects the addition of sodium bisulfite (NaHSO3) to imine bonds for ionization modification of imine COFs. The mild reaction conditions of adding aniline regulator in a one-pot process lay the foundation for its applicability.

[0006] The purpose of this invention is to construct a mild one-pot reaction method for ionizing several COFs. Solutions of amino and aldehyde monomers in benzyl alcohol are prepared and mixed in an acidic catalytic system, and reacted at 80-100 °C for 72 h to achieve uniform introduction of sulfonate anions into the framework in one step. After the reaction, iCOFs are obtained by solvent washing and drying.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a one-pot method for preparing imine covalent organic framework materials, wherein amino monomer and aldehyde monomer solutions are added to a reaction vessel, then aniline and sodium bisulfite are added, then AcOH is added, followed by vacuum degassing to remove water and oxygen and sealing, heating the reaction for 3-5 days, and after the reaction is completed, cooling, washing and drying are performed to obtain imine covalent organic framework materials.

[0008] Furthermore, the molar ratio of the amino monomer to the aldehyde monomer is 1:1, and the molar ratio of the amino monomer, aniline, and sodium bisulfite is 1:(8-15):(3-10).

[0009] Furthermore, the reaction temperature is 80~100℃.

[0010] One-pot ionization of imine-based covalent organic framework materials was prepared using the method described above.

[0011] Furthermore, the imine-based covalent organic framework material includes a two-dimensional covalent organic framework.

[0012] The imine-based covalent organic framework material is used to prepare Na-ion battery separators.

[0013] A diaphragm made from the aforementioned imine-based covalent organic framework material.

[0014] A method for preparing a diaphragm includes the following steps: adding carboxylated cellulose nanofibers (CNF), the imine covalent organic framework material, glycerol and deionized water to a beaker and sonicating; filtering using an aqueous filter membrane; immersing the dried membrane along with the filter membrane in tert-butanol to separate the membrane and the filter membrane; and freeze-drying the membrane to obtain a diaphragm.

[0015] An application of a separator as a separator in Na-ion batteries.

[0016] The specific procedure involves introducing a quantitative solution of amino and aldehyde monomers (containing NaHSO3) into a Shrek tube, adding AcOH, rapidly degassing under vacuum for 10 seconds to remove water and oxygen, and then sealing the tube. The reaction is then carried out for three days using an aluminum heating module. After the reaction cools down, the tube is cleaned with a large amount of deionized water, then thoroughly cleaned with tetrahydrofuran and filtered. Finally, the tube is dried overnight under vacuum conditions.

[0017] Furthermore, the method for preparing the amino monomer solution includes weighing a quantitative amount of the amino monomer and dissolving it in benzyl alcohol, then dissolving it by sonication to prepare a 0.08 M solution.

[0018] Furthermore, the method for preparing the aldehyde monomer solution includes: weighing the aldehyde monomer quantitatively and dissolving it in benzyl alcohol to prepare a 0.08 M solution, then adding 10 equivalents of aniline and 5-10 equivalents of sodium bisulfite to the solution and ultrasonically mixing it.

[0019] Furthermore, the reaction temperature was 80 °C, and the vacuum drying temperature was 70 °C.

[0020] Application areas of a one-pot method for ionizing imine covalent organic frameworks using in-situ addition of sodium bisulfite to imine bonds: preparation of membranes by composite with carboxylated cellulose nanofibers for use in Na-ion solid-state battery membranes.

[0021] Compared with existing technologies, the technical advantages of this invention are as follows: This ionization strategy preserves structural integrity, avoids post-modification pore blockage, and achieves high conversion rate and high crystallinity; it exhibits excellent electrochemical performance, with uniform and dense distribution of framework anions, suppressing dendrite formation; it uses inexpensive ionization reagents and monomers, maintaining synthetic economy and circumventing the barriers to ion monomer synthesis; the process is shorter, green and low-carbon, and holds promise for the industrial-scale mass production of iCOFs solid-state battery separators. This separator imparts a battery efficiency of 0.16 mAh g⁻¹. -1 The discharge specific capacity significantly improves the system's energy density. In long-cycle testing of symmetric cells (0.2 mA cm⁻¹), this is achieved.-2 It achieved over 1500 hours of extremely stable operation, with overpotential maintained at an extremely low level of approximately ±0.1 V; even at 0.5 mA cm⁻¹ -2 Even at high magnification, it still maintains extremely low and stable interface impedance. Attached Figure Description

[0022] Figure 1 This is the infrared spectrum of TAPB-DMTA COF one-pot ionization in Example 1;

[0023] Figure 2 This is the X-ray diffraction pattern of TAPB-DMTA COF one-pot ionization in Example 1;

[0024] Figure 3 This is the infrared spectrum of Py-1P COF one-pot ionization in Example 2;

[0025] Figure 4 This is the X-ray diffraction pattern of Py-1P COF one-pot ionization in Example 2;

[0026] Figure 5 This is a scanning electron microscope and energy dispersive spectroscopy (EDS) image of TAPB-DMTA COF one-pot ionization in Example 1.

[0027] Figure 6 This is a diagram illustrating the preparation of the TAPB-DMTA-SO3Na COF battery separator in Example 3.

[0028] Figure 7 This is a performance test diagram of the TAPB-DMTA-SO3Na COF battery in Example 3. Detailed Implementation

[0029] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0030] A one-pot method for constructing iCOFs is invented: using sodium bisulfite as an ionizing agent, imine bonds are added in situ to form amine bonds under acidic catalytic conditions, and sulfonate anions and counter cations are introduced. The reaction temperature is 80~100℃ and the reaction time is 72 hours.

[0031] The trial system includes 2D COFs.

[0032] Example 1

[0033] (1) The synthesis steps of TAPB-DMTA-SO3Na COF are as follows:

[0034]

[0035] 14 mg of TAPB monomer was weighed and dissolved in 0.5 mL of benzyl alcohol, and the solution was sonicated to prepare a 0.08 M solution. 11.6 mg of DMTA monomer was weighed and dissolved in 0.5 mL of benzyl alcohol to prepare a 0.08 M solution. Then, 10 equivalents (54 μL) of aniline and 5 equivalents (31.25 mg) of sodium bisulfite were added to the solution, and the mixture was sonicated to homogenize. The TAPB and DMTA monomer solutions were introduced into a Shrek tube, and 200 μL of pure AcOH was added. The tube was rapidly degassed under vacuum for 10 s to remove water and oxygen, and then sealed. The reaction was carried out for three days at 100 °C using an aluminum heating module. After cooling, the tube was washed with a large amount of deionized water, then thoroughly washed with tetrahydrofuran, filtered, and dried overnight under vacuum at 70 °C. TAPB-DMPA-SO3Na was obtained in 75% yield.

[0036] Example 2

[0037] (2) The synthesis steps of Py-1P-SO3NaCOF are as follows:

[0038]

[0039] 22 mg of TAPPy monomer was weighed and dissolved in 0.5 mL of benzyl alcohol, and the solution was sonicated to prepare a 0.08 M solution. 5.4 mg of TA monomer was weighed and dissolved in 0.5 mL of benzyl alcohol to prepare a 0.08 M solution. Then, 10 equivalents of aniline and 7.5 equivalents of sodium bisulfite were added to the solution, and the mixture was sonicated to mix thoroughly. The TAPB and DMTA monomer solutions were introduced into a Shrek tube, and 200 μL of 6M AcOH was added. The tube was rapidly degassed under vacuum for 10 s to remove water and oxygen, and then sealed. The reaction was carried out for three days at 80 °C using an aluminum heating module. After cooling, the tube was washed with a large amount of deionized water, then thoroughly washed with tetrahydrofuran, filtered, and dried overnight under vacuum at 70 °C. Py-1p-SO3Na was obtained in 73% yield.

[0040] Figure 1 , 3 The infrared spectrum shown indicates the transformation of the imine bond and the introduction of the sulfonic acid group. Figure 2 , 4 The XRD pattern shown indicates that, compared with the standard synthesis methods for various two-dimensional COFs, this ionization synthesis method can largely retain their original crystallinity. Figure 5 Scanning electron microscopy and energy dispersive spectroscopy showed that Na and S were uniformly distributed within the framework, indicating a high degree of modification.

[0041] Example 3

[0042] Preparation and application of the membrane: 1.25 g CNF, 6.25 mg TAPB-DMTA-SO3NaCOF, and 1.3 μL glycerol were added to a 25 mL beaker, followed by 10-15 mL of deionized water. The mixture was sonicated for 10 min using an ultrasonic cell disruptor. The mixture was then filtered using an aqueous filter membrane (filter cake diameter 42.7 mm, the inner diameter of a cylindrical glass funnel). The dried membrane, along with the filter membrane, was immersed in tert-butanol to separate the membrane and filter membrane. The membrane was then immersed in a large amount of tert-butanol, with the solution changed every 8-12 h, for a total soaking time of 24-36 h. The membrane was quickly transferred to a culture dish, minimizing tert-butanol evaporation from the surface. The dish was covered with plastic wrap, leaving uniform vent holes in the wrap. The culture dish was then transferred to the freezer overnight. Once the film is confirmed to be frozen solid, it can be freeze-dried. Turn on the freeze dryer beforehand, and once it is ready, remove the film from the freezer to prevent the tert-butanol from melting. Freeze-dry for approximately 6 hours; the result should look like... Figure 6 The diaphragm shown.

[0043] The obtained membrane was assembled into a solid-state sodium-ion battery. Figure 7 The test results show that the TAPB-DMTA-SO3Na ionic COF separator exhibits excellent overall performance in solid-state batteries. Firstly, this separator contributes to a battery performance of 0.16 mAh g⁻¹. -1 The discharge specific capacity significantly improves the system's energy density. Secondly, in long-cycle testing of symmetrical cells (0.2 mAcm⁻¹), the discharge specific capacity is significantly improved. -2 It achieved over 1500 hours of extremely stable operation, with overpotential maintained at an extremely low level of approximately ±0.1 V; even at 0.5 mA cm⁻¹ -2 Even at high rates, it maintains extremely low and stable interfacial impedance. Furthermore, this material also exhibits advantages in exchange current density. In summary, this separator effectively reduces solid-liquid interfacial impedance and significantly suppresses dendrite growth, providing an ideal material choice for constructing long-life, high-safety solid-state metal batteries.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the preparation of ionized imine-based covalent organic framework materials by one-pot, characterized in that: The amino monomer and aldehyde monomer solutions were added to the reaction vessel, followed by aniline and sodium bisulfite, and then AcOH was added. The mixture was then degassed under vacuum to remove water and oxygen, and sealed. The reaction was heated for 3-5 days. After the reaction was completed, the mixture was cooled, washed, and dried to obtain an imine covalent organic framework material.

2. The method of claim 1, wherein the method is characterized by: The molar ratio of the amino monomer to the aldehyde monomer is 1:1, and the molar ratio of the amino monomer, aniline and sodium bisulfite is 1:(8-15):(3-10).

3. The method of claim 1, wherein the method is characterized by: The reaction temperature is 80~100℃.

4. One-pot ionized imine-based covalent organic framework material, characterized in that: The imine-based covalent organic framework material is prepared using the preparation method described in any one of claims 1-3.

5. The one-pot ionization imine-based covalent organic framework material according to claim 4, characterized in that: The imine-based covalent organic framework material includes a two-dimensional covalent organic framework.

6. The application of the one-pot ionization of imine-based covalent organic framework materials as described in claim 4 or 5, characterized in that: The imine-based covalent organic framework material is used to prepare Na-ion battery separators.

7. A diaphragm, characterized in that: The diaphragm is made of the imine-based covalent organic framework material described in claim 4.

8. The method for preparing a diaphragm according to claim 7, characterized in that, The process includes the following steps: adding carboxylated cellulose nanofibers, the imine covalent organic framework material, glycerol, and deionized water to a beaker and sonicating; filtering using an aqueous filter membrane; immersing the dried membrane along with the filter membrane in tert-butanol to separate the membrane and the filter membrane; and freeze-drying the membrane to obtain a diaphragm.

9. The application of the separator according to claim 7 as a separator for Na-ion batteries.

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