Copper-based truxene metal organic framework positive electrode material, preparation method and application

Abstract

The invention provides a copper-based truxene metal organic framework positive electrode material, a preparation method and application, and belongs to the technical field of aqueous zinc ion battery positive electrode materials. The method comprises the following steps: adding hexahydroxy truxene, benzoic acid and copper nitrate into a mixed solution of N, N-dimethylformamide and water, filling the mixed solution into a hydrothermal kettle for constant-temperature storage, and finally washing and drying a product to obtain the copper-based truxene organic metal framework positive electrode material. The preparation method of the positive electrode material is simple in process operation, and the positive electrode material has relatively good cycling stability and relatively large specific capacity and shows relatively good electrochemical performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of positive electrode materials of aqueous zinc ion batteries, and particularly relates to a copper-based triindole metal organic framework positive electrode material, a preparation method and application. BACKGROUND

[0002] With the continuous development of clean and renewable energy, it is imperative to develop large-scale energy storage systems to solve the uneven distribution of time and space. Although lithium ion batteries have high energy density, their cost is high, and there are safety hazards of fire and explosion. As a new type of energy storage system with high safety and environmental protection, aqueous zinc ion batteries have the characteristics of high theoretical capacity (820 mAh·g -1 ) and low redox potential (relative to the standard hydrogen electrode -0.762 V). Therefore, as an effective supplement to lithium ion batteries, aqueous zinc ion batteries are very suitable for large-scale energy storage applications.

[0003] Generally, an aqueous zinc ion battery is composed of a metal zinc negative electrode, an electrolyte and a positive electrode material. The properties of the positive electrode material are closely related to the charging and discharging process of the battery, thereby directly affecting the overall performance of the battery. Compared with traditional vanadium-based and manganese-based materials, metal organic frameworks (MOF) have a porous nanostructure, high porosity and large specific surface area, which are more conducive to the storage of zinc ions. At the same time, selecting organic compounds with a conjugated system as ligands can also improve the overall conductivity of the material, thereby alleviating polarization and improving the cycle performance of the battery. Therefore, developing a MOF with good zinc storage capacity and applying it as a positive electrode in an aqueous zinc ion battery is a very promising solution. SUMMARY

[0004] The purpose of the present application is to provide a copper-based triindole metal organic framework positive electrode material, which is applied to an aqueous zinc ion battery and has good cycle stability and high specific capacity.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0006] The present application first provides a preparation method of a copper-based triindole metal organic framework positive electrode material, comprising the following steps:

[0007] Step one: configure N,N-dimethylformamide and water into a mixed solution;

[0008] Step two: mix 2,3,7,8,12,13-hexahydroxytrindole, benzoic acid and copper nitrate with the mixed solution of step one, and ultrasonically stir until dispersed to obtain a reaction solution;

[0009] Step three: transferring the reaction solution obtained in step two to a hydrothermal kettle to perform hydrothermal reaction, to obtain a product;

[0010] Step four: centrifugal separation, washing and drying of the product obtained in step three to obtain a copper-based truxene metal organic framework positive electrode material.

[0011] Preferably, the volume ratio of N,N-dimethylformamide and water in step one is 1:1.

[0012] Preferably, the molar ratio of 2,3,7,8,12,13-hexahydroxytruxene, benzoic acid and copper nitrate in step two is 1:1:1.5.

[0013] Preferably, the temperature of the hydrothermal reaction in step three is 80-90℃, and the reaction time is 18-24h.

[0014] Preferably, the washing frequency in step four is 3 times, the vacuum drying temperature is set to 80-90℃, and the drying time is 24-48h.

[0015] The application also provides a copper-based truxene metal organic framework positive electrode material obtained by the above preparation method.

[0016] The application also provides application of the above copper-based truxene metal organic framework positive electrode material in a water-based zinc ion battery.

[0017] Preferably, the application specifically includes:

[0018] 1) mixing and grinding the copper-based truxene metal organic framework positive electrode material, Ketjen black and a binder, then using N-methyl pyrrolidone to prepare a slurry, uniformly coating the slurry on a titanium foil, and drying to obtain a positive electrode;

[0019] 2) using the positive electrode prepared in step 1) to assemble a battery by the inverted method, from bottom to top, the negative electrode shell, stainless steel spring, stainless steel gasket, zinc sheet, electrolyte, glass fiber diaphragm, electrolyte, positive electrode sheet, positive electrode shell, and after assembly, using a battery sealing machine to seal and compress, to obtain a water-based zinc ion button cell.

[0020] Advantages of the application

[0021] This invention provides a copper-based trimeric indene metal-organic framework (MOF) cathode material, its preparation method, and its application. The method involves adding hexahydroxytrimeric indene, benzoic acid, and copper nitrate to a mixed solution of N,N-dimethylformamide and water, filling the solution in a hydrothermal reactor for constant temperature storage, and finally washing and drying the product to obtain the copper-based trimeric indene MOF cathode material. This invention uses 2,3,7,8,12,13-hexahydroxytrimeric indene as the MOF ligand, with hydroxyl active sites distributed at the ends of the three epitaxial arms. After reacting with copper ions to obtain the MOF, the material forms a hexagonal honeycomb structure at the microscopic level, resulting in a uniform distribution of reactive active sites, while the internal formation of approximately... The porous structure is suitable for zinc ion storage. Using this material as the positive electrode in aqueous zinc-ion batteries results in good cycle stability and high specific capacity. This invention employs a hydrothermal method for MOF synthesis, selecting copper nitrate as the metal source and adding an appropriate amount of benzoic acid to adjust the solution pH, which effectively suppresses side reactions and avoids impurity formation. Furthermore, compared to interfacial synthesis methods for similar MOFs, the hydrothermal synthesis method is simpler and faster, and yields higher MOFs, making it suitable for mass production. Attached Figure Description

[0022] Figure 1 The image shows the X-ray diffraction pattern of the sample from Example 1.

[0023] Figure 2 This is a scanning electron microscope image of the sample from Example 1.

[0024] Figure 3 The sample from Example 1 was used as the positive electrode material for an aqueous zinc-ion battery at 0.01 A·g. -1 Cyclic performance graph of current density.

[0025] Figure 4 The sample from Example 1 was used as the positive electrode material for an aqueous zinc-ion battery at 0.1 A·g -1 Cyclic performance graph of current density.

[0026] Figure 5 The graph shows the rate performance of the sample from Example 1 as the positive electrode material for an aqueous zinc-ion battery. Detailed Implementation

[0027] This invention first provides a method for preparing a copper-based tri-indene metal-organic framework cathode material, comprising the following steps:

[0028] Step 1: Prepare a mixed solution by mixing N,N-dimethylformamide and water; the volume ratio of N,N-dimethylformamide to water is preferably 1:1.

[0029] Step 2: Mix 2,3,7,8,12,13-hexahydroxytrimeric indene, benzoic acid, and copper nitrate with the mixed solution from Step 1, and ultrasonically stir until dispersed. The ultrasonication time is preferably 3-5 minutes, and the stirring time is preferably 2-3 minutes to obtain a reaction solution. The molar ratio of 2,3,7,8,12,13-hexahydroxytrimeric indene, benzoic acid, and copper nitrate is preferably 1:1:1.5.

[0030] In step two, 2,3,7,8,12,13-hexahydroxytrimeric indene has the following structure:

[0031]

[0032] Step 3: Transfer the reaction solution obtained in Step 2 to a hydrothermal reactor for hydrothermal reaction. The preferred temperature of the hydrothermal reaction is 80-90℃, more preferably 90℃, and the preferred reaction time is 18-24 hours, more preferably 18 hours, to obtain the product.

[0033] Step 4: The product obtained in Step 3 is centrifuged, washed, and dried to obtain a copper-based trimeric indene metal-organic framework cathode material. The washing process preferably uses N,N-dimethylformamide, anhydrous ethanol, and water sequentially, with the washing cycle preferably three times. The vacuum drying temperature is preferably set to 80–90°C, and the drying time is preferably 24–48 hours.

[0034] The present invention also provides a copper-based triindene metal-organic framework cathode material obtained by the above preparation method.

[0035] The present invention also provides the application of the above-mentioned copper-based triindene metal-organic framework cathode material in water-washed zinc-ion batteries.

[0036] According to the present invention, the preferred application includes:

[0037] 1) The copper-based indene metal-organic framework cathode material, Ketjen black, and binder are mixed and ground, and then a slurry is prepared using N-methylpyrrolidone. This slurry is uniformly coated onto titanium foil and dried to obtain the cathode. The preferred mass ratio of the copper-based indene metal-organic framework cathode material, Ketjen black, and binder is 7:2:1. The preferred binder is polyvinylidene fluoride. The preferred drying temperature is 80°C, and the preferred drying time is 12 hours.

[0038] 2) Using the positive electrode prepared by the above steps, assemble the battery by inverted method. From bottom to top, the components are negative electrode shell, stainless steel spring sheet, stainless steel gasket, zinc sheet, electrolyte, glass fiber separator, electrolyte, positive electrode sheet, and positive electrode shell. After assembly, use a battery sealing machine to seal and press it to obtain an aqueous zinc ion button battery.

[0039] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments can be purchased through conventional commercial channels unless otherwise specified.

[0041] Example 1: Preparation of copper-based tri-indene MOF cathode material

[0042] 1. Mix 35 mL of N,N-dimethylformamide and 35 mL of deionized water and stir for 5 minutes to prepare a mixed solution.

[0043] 2. In a beaker, mix 40 mg of 2,3,7,8,12,13-hexahydroxytrimeric indene, 40 mg of benzoic acid, and 30.2 mg of copper nitrate trihydrate with the solution obtained in step 1, sonicate for 5 minutes, and then stir for 3 minutes to completely disperse the system.

[0044] 3. Transfer the system from step 2 to a hydrothermal reactor and store it in a 90°C oven for 18 hours.

[0045] 4. Take out the liquid obtained in step 3 and centrifuge it at 8000 r / min for 5 minutes to separate the solid matter. Then wash it sequentially with N,N-dimethylformamide, anhydrous ethanol, and deionized water. The amount of detergent used each time is 20 mL, and each wash is performed three times.

[0046] 5. The solid material obtained in step 4 was vacuum dried at 80°C for 12 hours to obtain copper-based triindene MOF cathode material.

[0047] The X-ray diffraction results of the sample prepared in Example 1 are as follows: Figure 1 As shown,

[0048] Scanning electron microscope images of the sample prepared in Example 1 are shown below. Figure 2 As shown, Figure 2 It can be seen that the obtained MOF is in the form of amorphous particles.

[0049] Example 2: Application of copper-based tri-indene MOF cathode material

[0050] The sample from Example 1 was prepared into a positive electrode sheet. Using 1 mL of N-methylpyrrolidone as a dispersant, 70 mg of the final product from Example 1, 20 mg of Ketjen black, and 10 mg of polyvinylidene fluoride were stirred evenly to obtain a bindable slurry. This slurry was coated onto titanium foil and then dried in a vacuum oven at 80°C for 12 hours. The slurry was then cut into 12 mm positive electrode sheets using a slicing machine.

[0051] Zinc foil with a thickness of 100 μm was cut into 15 mm discs using a slicer. These discs were then sanded, cleaned with ethanol, and dried to serve as the negative electrode. Full cells were assembled under atmospheric conditions. GF / D glass fiber membranes were cut into 19 mm discs to serve as the battery separator. The electrolyte was a 2 mol / L zinc sulfate aqueous solution, used in a volume of 80 μL per button cell. Constant current charge-discharge cycle testing of the batteries was conducted at room temperature using a Newway battery testing system.

[0052] The electrochemical cycling performance of the full cell composed of the sample in Example 1 at a current density of 0.01 A / g is as follows: Figure 3 As shown, the discharge specific capacity in the first cycle is 52.9 mAh / g, and after 50 cycles it is 39.9 mAh / g. Figure 4 As shown, when the current density is 0.1 A / g, the specific capacity during the first charge-discharge cycle is 58.8 mAh / g, and after 200 cycles it is 50.1 mAh / g. These data indicate that the copper-based tri-indene MOF exhibits good stability.

[0053] The rate performance of the full battery cell composed of the sample in Example 1 is as follows: Figure 5 As shown, the reversible capacities of the full cell at current densities of 0.01, 0.02, 0.05, 0.1, 0.2, and 0.5 A / g are 71, 64, 53, 48, 43, and 36 mAh / g, respectively. When the current density recovers to 0.01 A / g, the average discharge specific capacity rebounds to 57 mAh / g, demonstrating good rate performance.

[0054] In summary, the method for preparing the battery cathode material provided by this invention is simple to operate. The battery cathode material is a copper-based tri-indene organometallic framework. When the prepared battery cathode material is used in an aqueous zinc-ion battery, it exhibits a large charge-discharge specific capacity and good cycle stability.

[0055] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a copper-based tri-indene metal-organic framework cathode material, characterized in that, Includes the following steps: Step 1: Prepare a mixed solution by mixing N,N-dimethylformamide and water; Step 2: Mix 2,3,7,8,12,13-hexahydroxytri-indene, benzoic acid, and copper nitrate with the mixed solution from Step 1, and sonicate until dispersed to obtain the reaction solution; Step 3: Transfer the reaction solution obtained in Step 2 to a hydrothermal reactor for hydrothermal reaction to obtain the product; Step 4: The product obtained in Step 3 is centrifuged, washed, and dried to obtain copper-based tri-indene metal-organic framework cathode material.

2. The method for preparing a copper-based tri-indene metal-organic framework cathode material according to claim 1, characterized in that, In step one, the volume ratio of N,N-dimethylformamide to water is 1:

1.

3. The method for preparing a copper-based tri-indene metal-organic framework cathode material according to claim 1, characterized in that, In step two, the molar ratio of 2,3,7,8,12,13-hexahydroxytrimeric indene, benzoic acid and copper nitrate is 1:1:1.

5.

4. The method for preparing a copper-based tri-indene metal-organic framework cathode material according to claim 1, characterized in that, In step three, the hydrothermal reaction temperature is 80–90℃, and the reaction time is 18–24 hours.

5. The method for preparing a copper-based tri-indene metal-organic framework cathode material according to claim 1, characterized in that, In step four, the washing is performed three times, the vacuum drying temperature is set to 80-90℃, and the drying time is 24-48 hours.

6. The copper-based tri-indene metal-organic framework cathode material obtained by the preparation method of claim 1.

7. The application of the copper-based tri-indene metal-organic framework cathode material according to claim 6 in a water-washable zinc-ion battery.

8. The application according to claim 7, characterized in that, The specific applications include: 1) After mixing and grinding copper-based triindene metal-organic framework cathode material, Ketjen black and binder, N-methylpyrrolidone is used to make a slurry, which is then uniformly coated on titanium foil and dried to obtain the cathode. 2) Using the positive electrode prepared in step 1), assemble the battery using the inverted method. From bottom to top, the components are negative electrode shell, stainless steel spring sheet, stainless steel gasket, zinc sheet, electrolyte, glass fiber separator, electrolyte, positive electrode sheet, and positive electrode shell. After assembly, use a battery sealing machine to seal and press the battery to obtain an aqueous zinc-ion button battery.

Images