A post-synthetic modified COFs material with sodium ion battery performance and its preparation method
By introducing suitable monomers and two-dimensional nanosheet structures into COFs materials and compounding them with reduced graphene oxide, and then performing sulfurization modification, the shortcomings of COFs materials in improving the electrochemical performance in sodium ion batteries were solved, and excellent charge and discharge performance and long cycle stability at high current density were achieved.
Patent Information
- Application Number
- CN202211204945.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-29
- Publication Date
- 2025-09-19
- Estimated Expiration
- 2042-09-29
AI Technical Summary
There is little research on improving the electrochemical performance of existing COFs materials in sodium-ion batteries, and there is a lack of effective post-synthesis modification methods to improve their performance.
By selecting suitable monomers and two-dimensional nanosheet structures to compound with reduced graphene oxide and perform sulfurization modification, the C=O double bond is converted into a C=S double bond, the sodium ion binding ability is enhanced, and COFs materials with excellent performance are prepared.
The electrochemical activity and capacity of COFs materials are significantly improved, especially maintaining good charge and discharge performance and long cycle stability at high current density, showing excellent rate performance and long cycle life.
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Figure CN115621440B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of sodium ion battery materials, and in particular relates to a post-synthetic modified COFs material with sodium ion battery performance and a preparation method thereof. Background Art
[0002] Polymer sodium-ion battery cathode materials are a new type of cathode material that utilizes specific functional groups or organic structural units as active sites to achieve the storage and conversion of sodium ions. The unique macromolecular chain structure of polymers makes them difficult to dissolve in electrolytes, and the active substances are not easily lost during battery reactions. Therefore, this type of electrode material has a certain degree of electrochemical stability. Through rational monomer selection and molecular design, polymer electrode materials with abundant active sites can be obtained. Their electrochemical performance even far exceeds that of traditional inorganic electrode materials, and therefore they have attracted widespread attention.
[0003] Covalent organic frameworks (COFs) are special polymer materials whose periodic pore structures provide ion channels and reaction sites for electrochemical processes. They are very suitable for application as electrode materials in actual battery testing, and have achieved certain research results in the fields of lithium-ion batteries or sodium-ion batteries. At present, electrochemical research on this type of material mainly focuses on structural design and layer exfoliation treatment, while there is less research on post-synthetic modification of COFs materials to achieve improved electrochemical performance. In summary, a COFs material that can be modified post-synthetically to improve the performance of sodium-ion batteries has high research value. Summary of the Invention
[0004] Objective of the present invention: To provide a post-synthetic modified COFs material with sodium-ion battery performance and a method for its preparation, addressing the lack of knowledge regarding post-synthetic modification of COFs to enhance electrochemical activity and capacity. This invention aims to provide a novel strategy for applying this post-synthetic modification of COFs to the functionalization of porous structures, thus opening up new avenues for the development of polymer electrode materials.
[0005] The technical solution of the present invention is: To achieve the above-mentioned purpose, the present invention is realized by the following technical solution:
[0006] A post-synthetic modified COF material with sodium-ion battery performance and its preparation method are characterized by: appropriate monomer functional group selection, wherein the appropriate monomer is a triamine monomer with more active sites to achieve superior performance; a two-dimensional nanosheet structure, wherein the two-dimensional nanosheet structure is composited with reduced graphene oxide (rGO) to expose more active sites within the pores; and functional group sulfurization modification, wherein the sulfurization modification converts C=O double bonds to C=S double bonds to enhance binding capacity with sodium ions. Therefore, the COF material obtained through morphology control, molecular design, and post-synthetic sulfurization modification is a polymer sodium-ion battery cathode material with excellent performance.
[0007] The present invention adds rGO nanosheets during the COFs synthesis process to prepare a two-dimensional COFs and rGO composite material, and then obtains a post-synthesis modified COFs material with sodium ion battery performance through a sulfurization modification method. The specific steps are:
[0008] Step (1) In a 25 mL Schlenk tube, 10-50 mg of rGO powder was dispersed in a mixed organic solvent and stirred for 10-120 min until the rGO powder was uniformly dispersed;
[0009] Step (2) adding suitable monomers to the solvent of step (1) and stirring for a period of time to obtain a uniform solution.
[0010] Step (3) The solution obtained in the above step (2) is subjected to multiple freeze-evacuation-thaw cycles in liquid nitrogen, the interior of the solution reactor is evacuated, and the reactor is completely sealed.
[0011] Step (4) placing the above reactor in a forced air drying oven and keeping it at 180-220° C. for 4-6 days.
[0012] Step (5) After the insulation of the reactor in step (4) is completed, the reactor is cooled to room temperature, washed with N,N-dimethylformamide (DMF) and acetone, and finally dried at room temperature.
[0013] In step (6), the dried product is collected and subjected to Soxhlet extraction using tetrahydrofuran as an extractant for 2-4 days until the filtrate becomes colorless, and the product is then collected.
[0014] Step (7) The above product is vacuum dried at 100-140° C. for 12-48 hours to remove the residual organic solvent in the pores to obtain product A.
[0015] Step (8) 10-100 mg of the pre-prepared product A and 40-400 mg of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiodiphosphatane-2,4-disulfide (Lawesson's reagent) were added to a 250 mL round-bottom flask, and 20-120 mL of toluene was added as the reaction solvent.
[0016] Step (9) ultrasonically treat the mixed solution for a period of time until the reactants are uniformly dispersed, and reflux the mixture at 100-150° C. for 24-72 hours under an inert gas atmosphere.
[0017] Step (10) After the reaction is completed and cooled to room temperature, the crude product is filtered and dried to obtain a crude product. The crude product is then subjected to Soxhlet extraction using methanol as an extractant for 5 days until the filtrate becomes colorless, and the product is collected.
[0018] Step (11) The above product is vacuum dried at 100-140° C. for 12-48 hours to remove the residual organic solvent in the pores to obtain product B.
[0019] Furthermore, in step (1), the organic solvent used can be a mixed solvent of 1,3-dimethyl-2-imidazolidinone (DMI, 1-4 mL) / mesitylene (0.5-4 mL) / isoquinoline (0.1-1 mL). In step (2), the monomers used can be 10-50 mg of tris(4-aminophenyl)amine (TAPA) and 20-60 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA). Product A prepared using the above solvent and monomers is TAPA-COFs, and product B prepared is S@TAPA-COFs.
[0020] Furthermore, in step (1), the organic solvent used can be a mixed solvent of N-methylpyrrolidone (NMP, 1-4 mL) / mesitylene (0.5-4 mL) / isoquinoline (0.1-1 mL). In step (2), the monomers used can be 10-50 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and 20-60 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA). Product A prepared using the above solvent and monomers is TAPT-COFs, and product B prepared is S@TAPT-COFs.
[0021] Furthermore, all working electrodes, composed of the product COFs material (60%), conductive carbon black (30%), and polyvinylidene fluoride (PVDF) as a binder (10%), were coated onto an aluminum current collector and dried in vacuum at 60°C for at least 12 hours. Coin-type cells were assembled in an argon-filled glove box with oxygen and water concentrations less than 1 ppm. Sodium metal discs were used as the negative electrode, 1 mol / L sodium perchlorate solution as the electrolyte, and glass fiber filter paper as the separator. Discharge / charge performance measurements included charge / discharge specific capacity-cycling performance and charge / discharge specific capacity at different current densities.
[0022] Beneficial effects:
[0023] (1) The present invention proposes a post-synthetic modified COFs material with sodium electrical properties and a preparation method thereof.
[0024] (2) Unique structure: The monomers selected for synthesis contain more highly active functional groups, due to their characteristic nanosheet structure exposing more active sites and pore structures, as well as some C=S highly active functional groups formed by sulfur modification.
[0025] (3) Excellent performance: The performance of the COFs material modified after post-synthesis is further improved compared with the unmodified material. At the same time, the best-performing S@TAPT-COFs composite material can still maintain an effective charge and discharge process under conditions of higher current density such as 2.0A / g. At the same time, at current densities of 0.1, 0.2, 0.5, 1.0, and 2.0A / g, the discharge specific capacity reaches 109.3, 88.5, 78.8, 73.2, and 68.5mAh / g, respectively. At the same time, when the current density returns to 0.1A / g, the specific capacity can return to 102.0mAh / g, which is an excellent rate performance. After 2000 cycles of ultra-long cycle charge and discharge at a current density of 2.0A / g, the battery specific capacity can still reach 68.6mAh / g, showing excellent long-term cycle stability.
[0026] (4) Compared with other methods, this preparation method has the following advantages:
[0027] ① Compared with traditional synthesis processes, this method is easier to form two-dimensional COFs nanosheets with better electrochemical properties;
[0028] ② This post-synthesis modification treatment does not damage the original COFs skeleton structure and can effectively maintain its porous structure;
[0029] (5) This post-synthesis modification treatment method can be well applied to the functionalization of porous structures, which provides new ideas for the development of polymer electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 Schematic diagram of the preparation process of Examples 1-4.
[0031] Figure 2 The following is a Fourier transform infrared spectrum of the product of Example 1-4.
[0032] Figure 3 The charge-discharge capacity-cycle number curves of the products of Examples 1-4 under 100 cycles and the charge-discharge capacity-cycle number curves at different current densities are shown.
[0033] Figure 4 It is a simple preparation process. DETAILED DESCRIPTION
[0034] The specific implementation methods of the material preparation in the present invention are as follows:
[0035] Example 1: In a 25 mL Schlenk tube, 33 mg of rGO powder was dispersed in a mixed solvent of 1,3-dimethyl-2-imidazolidinone (DMI, 3 mL) / mesitylene (1 mL) / isoquinoline (0.4 mL) and stirred for 1 h. Then, 20 mg of tris(4-aminophenyl)amine (TAPA) and 27.71 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) were added and stirred for 20 min to obtain a homogeneous solution. Three freeze-pump-thaw cycles were then performed in liquid nitrogen. After evacuating the solution reactor to 0.005 mmHg, the reactor was completely sealed. The reactor was placed in a forced air drying oven at 200°C for 5 days. After cooling to room temperature, the solution was washed with N,N-dimethylformamide (DMF) and acetone and dried at room temperature. After the dried product was collected, Soxhlet extraction was performed using tetrahydrofuran as the extraction solvent for 3 days until the filtrate was colorless. The product was then collected and vacuum-dried at 120°C for 24 hours to remove the residual organic solvent inside the pores, ultimately obtaining product A1 - TAPA-COFs.
[0036] Example 2: 60 mg of pre-prepared TAPA-COFs composite material and 200 mg of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiodiphosphatane-2,4-disulfide (Lawson's reagent) were added to a 250 mL round-bottom flask, and 70 mL of toluene was added as the reaction solvent. The mixed solution was sonicated for 20 minutes until the reactants were evenly dispersed, and then refluxed at 120°C under a N2 atmosphere for 48 hours. After cooling to room temperature, the crude product was transitionally dried. Soxhlet extraction was carried out using methanol as the extraction solvent for 5 days until the filtrate was colorless. The product was then vacuum dried at 120°C for 24 hours to remove the residual organic solvent inside the pores, obtaining the final product B1 - S@TAPA-COFs.
[0037] Example 3: In a 25 mL Schlenk tube, 25 mg of rGO powder was dispersed in a mixture of N-methylpyrrolidone (NMP, 2 mL) / mesitylene (2 mL) / isoquinoline (0.4 mL) and stirred for 1 h. Then, 45 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and 55.42 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) were added and stirred for 20 min to obtain a homogeneous solution. Three freeze-pump-thaw cycles were then performed in liquid nitrogen. After evacuating the solution reactor to 0.005 mmHg, the reactor was completely sealed. The reactor was placed in a forced air drying oven at 200°C for 5 days. After cooling to room temperature, the solution was washed with N,N-dimethylformamide (DMF) and acetone and dried at room temperature. After the dried product was collected, Soxhlet extraction was performed using tetrahydrofuran as the extraction solvent for 3 days until the filtrate was colorless. The product was then collected and vacuum-dried at 120°C for 24 hours to remove the residual organic solvent inside the pores, ultimately obtaining product A2 - TAPT-COFs.
[0038] Example 4: 60 mg of pre-prepared TAPT-COFs composite material and 200 mg of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiodiphosphatane-2,4-disulfide (Lawson's reagent) were added to a 250 mL round-bottom flask, and 70 mL of toluene was added as the reaction solvent. The mixed solution was sonicated for 20 minutes until the reactants were evenly dispersed, and then refluxed at 120°C under a N2 atmosphere for 48 hours. After cooling to room temperature, the crude product was transitionally dried. Soxhlet extraction was carried out using methanol as the extraction solvent for 5 days until the filtrate was colorless. The product was then vacuum dried at 120°C for 24 hours to remove the residual organic solvent inside the pores, obtaining the final product B2 - S@TAPT-COFs.
[0039] Figure 1 Schematic diagram of the preparation process of Examples 1-4, showing the preparation process of Examples 1-4, as well as the structure of key monomer functional groups and COFs materials. Figure 2 The Fourier transform infrared spectra of Examples 1-4 are compared. By comparing the infrared spectra of Examples 1 and 2, and 3 and 4, it can be analyzed that the infrared spectra of the samples before and after organic vulcanization do not change significantly, indicating that the modification process of organic vulcanization does not cause too much damage to the framework structure of the material. Figure 3 a is the charge-discharge capacity-cycle number curve of the sodium ion battery assembled with the products of Examples 1-4 under 100 cycles. After 100 cycles, it still has good activity. Figure 3b is the charge and discharge specific capacity-number curve of the sodium ion battery assembled with the products of Examples 1-4 at different current densities. It can be seen that in Example 4, S@TAPT-COFs has a discharge specific capacity of 109.3, 88.5, 78.8, 73.2, and 68.5 mAh / g at current densities of 0.1, 0.2, 0.5, 1.0, and 2.0 A / g, respectively. At the same time, when the current density is restored to 0.1 A / g, the specific capacity can return to 102.0 mAh / g, which is an excellent rate.
Claims
1. A method for preparing a post-synthetic modified COFs material, wherein the COFs material is used as a positive electrode of a sodium ion battery, characterized in that: The following steps are involved: (1) In a 25 mL Schlenk tube, 10-50 mg of rGO powder was dispersed in a mixed solvent of 1-4 mL of 1.3-dimethyl-2-imidazolidinone, 0.5-4 mL of mesitylene, and 0.1-1 mL of isoquinoline, or a mixed solvent of 1-4 mL of N-methylpyrrolidone, 0.5-4 mL of mesitylene, and 0.1-1 mL of isoquinoline, and stirred for 10-120 min until uniformly dispersed. (2) adding 10-50 mg of tris(4-aminophenyl)amine and 20-60 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride or 10-50 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 20-60 mg of 1,4,5,8-naphthalenetetracarboxylic dianhydride to the solvent of step (1), stirring for 10-60 min to obtain a uniform solution; (3) subjecting the solution obtained in step (2) above to multiple freeze-evacuation-thaw cycles in liquid nitrogen, evacuating the interior of the solution reactor and completely sealing the reactor; (4) placing the reactor in a forced air drying oven and keeping it at 180-220°C for 4-6 days; (5) After the insulation is completed, the reactor in the above step (4) is cooled to room temperature, washed with a suitable mixed solution, filtered, and finally dried at room temperature; (6) After the dried product is collected, Soxhlet extraction is performed for 2-4 days until the filtrate is colorless, and then the product is collected; (7) vacuum drying the product at 100-140° C. for 12-48 h to remove the residual organic solvent in the pores to obtain product A; (8) 10-100 mg of the pre-prepared product A and a sulfiding agent were added to a 250 mL round-bottom flask and 20-120 mL of toluene was added as the reaction solvent. The sulfiding agent was 40-400 mg of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiodiphosphatane-2,4-disulfide; (9) Ultrasonicate the mixed solution for a period of time until the reactants are evenly dispersed, and reflux at 100-150°C for 24-72 hours under an inert gas atmosphere; (10) After the reaction is completed and cooled to room temperature, the crude product is filtered and dried, and Soxhlet extraction is performed for 5 days until the filtrate is colorless, and the product is collected; (11) The above product was dried under vacuum at 100-140°C for 12-48 hours to remove the residual organic solvent in the pores to obtain product B.
2. The method for preparing the post-synthesis modified COFs material according to claim 1, characterized in that: The freeze-evacuation-thawing cycle in step (3) is performed at least twice, and the vacuum degree is at least 0.005 mmHg.
3. The method for preparing the post-synthesis modified COFs material according to claim 1, characterized in that: The mixed solution used for washing in step (5) is N,N-dimethylformamide and acetone.
4. The method for preparing the post-synthesis modified COFs material according to claim 1, characterized in that: The extraction solvent used in the Soxhlet extraction in step (6) is tetrahydrofuran.
5. The method for preparing the post-synthesis modified COFs material according to claim 1, characterized in that: The extraction agent used in the Soxhlet extraction in step (10) is methanol.