Preparation method of amorphous MOF derived ZIF and use thereof

Abstract

The application discloses a preparation method of amorphous MOF derived ZIF and application thereof, and the preparation method comprises the following steps: preparing zinc nitrate hexahydrate and cobalt nitrate hexahydrate into solution A, preparing 2,5-dihydroxyterephthalic acid into solution B, carrying out a solvothermal reaction of solution A and solution B to obtain amorphous ZnCo-MOF powder; preparing the amorphous ZnCo-MOF powder into suspension C, dissolving 2-methylimidazole in an ethanol aqueous solution, adding triethylamine to form solution D, adding the suspension C into the solution D to react to obtain ZnCo-ZIF hollow nanosphere powder; placing the ZnCo-ZIF hollow nanosphere powder into argon for annealing treatment to obtain nitrogen-doped porous carbon hollow nanosphere material; uniformly mixing the nitrogen-doped porous carbon hollow nanosphere powder with selenium powder, and then placing the mixture into argon for annealing treatment to obtain zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere material. The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere prepared by the method is mainly applied to preparation of a negative electrode material of a high-performance sodium ion battery.

Description

Technical Field

[0001] This invention relates to the field of micro / nano composite material synthesis technology, specifically to a method for preparing amorphous MOF-derived ZIF and its applications. Background Technology

[0002] Sodium-ion batteries, with their advantages of abundant sodium resources and low cost, have attracted widespread attention from researchers both domestically and internationally, and are considered the best candidate to replace lithium-ion batteries in the field of large-scale energy storage. Sodium-ion batteries share a similar reaction mechanism with lithium-ion batteries, but the large radius of sodium ions makes their diffusion in the host material difficult. Therefore, the key to developing sodium-ion batteries is to find electrode materials with excellent cycle performance and rate capability.

[0003] Metal selenides possess high theoretical specific capacity, but their conductivity is unsatisfactory. Furthermore, they are prone to volume expansion during sodium insertion / extraction, leading to structural damage and poor cycle stability. Currently, constructing nanostructures and combining them with conductive carbonaceous materials are commonly used to mitigate volume expansion and improve conductivity. However, existing synthesis strategies are complex, and there is no simple method for converting amorphous MOFs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing amorphous MOF-derived ZIF and its applications, the prepared material of which can improve the electrochemical performance of sodium-ion battery anode electrode materials.

[0005] In one aspect of the present invention, a method for preparing amorphous MOF-derived ZIFs is provided. According to an embodiment of the present invention, the preparation method includes the following steps:

[0006] (1) Add zinc nitrate hexahydrate and cobalt nitrate hexahydrate to an ethanol solution and dissolve by sonication to form solution A;

[0007] (2) Add 2,5-dihydroxyterephthalic acid to an ethanol solution and dissolve it by sonication to form solution B;

[0008] (3) Slowly add solution A to solution B, stir thoroughly and carry out a solvothermal reaction. After natural cooling, centrifuge, wash and dry the product to obtain amorphous ZnCo-MOF powder.

[0009] (4) Disperse amorphous ZnCo-MOF powder in an ethanol aqueous solution to form a suspension C;

[0010] (5) Dissolve 2-methylimidazole in an aqueous ethanol solution, add triethylamine, place in a water bath and stir and keep at a constant temperature to form solution D;

[0011] (6) Slowly add suspension C to solution D, stir the reaction at a constant temperature, centrifuge the product, wash it several times with ethanol, and dry it to obtain ZnCo-ZIF hollow nanosphere powder.

[0012] (7) ZnCo-ZIF hollow nanosphere powder was annealed in an argon protective atmosphere to obtain ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder.

[0013] (8) After uniformly mixing ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder with selenium powder, the mixture was annealed in an argon protective atmosphere to obtain zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder.

[0014] In addition, the method for preparing amorphous MOF-derived ZIF according to the above embodiments of the present invention may also have the following additional technical features:

[0015] In some embodiments of the present invention, in step (1), the concentration of zinc nitrate hexahydrate is 0.02-0.03 mol / L and the concentration of cobalt nitrate hexahydrate is 0.01-0.02 mol / L; in step (2), the concentration of 2,5-dihydroxyterephthalic acid is 0.03-0.04 mol / L; and in step (5), the concentration of 2-methylimidazole is 160-170 g / L.

[0016] In some embodiments of the present invention, in step (3), the solvothermal reaction temperature is 120-160°C, the reaction time is 8-12 h, and the ethanol is used for washing 2-3 times.

[0017] In some embodiments of the present invention, in step (6), the temperature of constant temperature stirring is 60-80°C, the reaction time is 5-10 min, the drying temperature is 50-70°C, and the drying time is 6-12 h.

[0018] In some embodiments of the present invention, in step (7), the annealing temperature is 600–800°C, the heating rate is 2–5°C / min, and the holding time is 2–4h.

[0019] In some embodiments of the present invention, in step (8), the mass ratio of ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder to selenium powder is 1:1 to 1:2, the annealing temperature is 300 to 600°C, the heating rate is 2 to 5°C / min, and the holding time is 2 to 4 hours.

[0020] In another aspect of the present invention, the present invention proposes a zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder prepared according to the preparation method of the amorphous MOF-derived ZIF described above.

[0021] In another aspect of the invention, an application of the aforementioned zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder is proposed. According to embodiments of the invention, the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder is used to prepare anode materials for sodium-ion batteries.

[0022] In another aspect, the present invention provides a method for preparing a sodium-ion battery. According to an embodiment of the present invention, the preparation method includes the following steps:

[0023] The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder was uniformly mixed with conductive carbon black and polyvinylidene fluoride and dissolved in 1-methyl-2-pyrrolidone. The mixture was shaken to prepare an electrode slurry. The electrode slurry was then uniformly coated onto a copper foil and dried. The copper foil slices loaded with the electrode slurry were used as the negative electrode of the sodium-ion battery. The separator was made of glass fiber and the electrolyte was a binary electrolyte. The battery was assembled in an argon-filled glove box to obtain the sodium-ion battery.

[0024] In addition, the method for preparing a sodium-ion battery according to the above embodiments of the present invention may also have the following additional technical features:

[0025] In some embodiments of the present invention, the mass ratio of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder to conductive carbon black and polyvinylidene fluoride is 6:1:1 to 8:1:1; the drying temperature is 50 to 70°C, and the drying time is 6 to 12 hours; the electrolyte is sodium hexafluorophosphate; the size of the working electrode of the sodium-ion battery negative electrode is 10 to 12 mm; and the positive electrode material of the sodium-ion battery is a metallic sodium sheet.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1) The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared by this invention have the synergistic effect of bimetallic selenide and nitrogen-doped porous carbon coating. The carbon matrix obtained by ZIF carbonization coats the metal nanoparticles, which improves the electronic conductivity of the electrode material. Nitrogen doping expands the carbon interlayer spacing, making it easier for sodium ions with larger ionic radii to be inserted and extracted in the interlayer spacing, while providing abundant active sites to enhance ion storage.

[0028] 2) The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared by this invention have a hollow structure, a larger specific surface area, a lower density and a higher mass loading. The nanoscale structural units can shorten the transport distance of ions and electrons, and the ultra-high specific surface area allows it to fully contact the electrolyte. The hollow structure effectively adapts to the volume expansion during sodium ion insertion / extraction, and has outstanding rate performance and stable cycling performance.

[0029] 3) This invention provides a method for preparing amorphous MOF-derived ZIFs and nitrogen-doped porous carbon-coated bimetallic selenide composite materials. The method is simple, easy to operate, safe, pollution-free, and low in cost. The simple strategy for preparing zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres can also be extended to other MOF-based composite materials, further enriching the types of MOF structural materials and showing broad application prospects in energy storage, catalysis, and other fields. Attached Figure Description

[0030] Figure 1 FESEM image of amorphous 70Zn30Co-MOF nanospheres prepared in Example 1 of this invention;

[0031] Figure 2 The XRD diffraction pattern of the amorphous 70Zn30Co-MOF nanospheres prepared in Example 1 of this invention;

[0032] Figure 3 FESEM image of 70Zn30Co-ZIF hollow nanospheres prepared in Example 1 of this invention;

[0033] Figure 4 The XRD diffraction pattern of the 70Zn30Co-ZIF hollow nanospheres prepared in Example 1 of this invention;

[0034] Figure 5 Here is a FESEM image of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 1 of this invention;

[0035] Figure 6 This is a TEM image of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 1 of this invention;

[0036] Figure 7 The XRD diffraction pattern of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 1 of this invention;

[0037] Figure 8 FESEM image of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 2 of this invention;

[0038] Figure 9 The XRD diffraction pattern of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 2 of this invention;

[0039] Figure 10 The following is a rate performance diagram of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 3 of the present invention at different current densities;

[0040] Figure 11The graph shows the cycling performance of zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in Example 3 of this invention at a fixed current density. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing amorphous MOF-derived ZIF includes the following steps:

[0044] (1) Dissolve 0.1666g of zinc nitrate hexahydrate and 0.0698g of cobalt nitrate hexahydrate in 20mL of ethanol solution and sonicate to dissolve, forming solution A;

[0045] (2) Dissolve 0.1585g of 2,5-dihydroxyterephthalic acid in 20mL of ethanol solution and sonicate to form solution B;

[0046] (3) Slowly add solution A to solution B, stir thoroughly, transfer to a reaction vessel, place in a 160℃ oven for 10 hours, allow to cool naturally, centrifuge the product, wash with ethanol 3 times, and dry in a 60℃ oven to obtain amorphous 70Zn30Co-MOF powder.

[0047] (4) Disperse amorphous 70Zn30Co-MOF powder in a mixed solution of 5mL ethanol and 5mL deionized water to form suspension C;

[0048] (5) Dissolve 5g of 2-methylimidazole in a mixture of 15mL of ethanol and 15mL of deionized water, and add 424μL of triethylamine. Dissolve by sonication to form solution D.

[0049] (6) The suspension C was slowly added dropwise to the solution D. After stirring in a 70°C water bath for 5 min, the product was centrifuged, washed three times with ethanol, and then dried in a 60°C oven for 12 h to obtain 70Zn30Co-ZIF hollow nanosphere powder.

[0050] (7) 70Zn30Co-ZIF hollow nanosphere powder was placed in an argon protective atmosphere and heated to 700℃ at a heating rate of 2℃ / min and held for 2h to obtain nitrogen-doped porous carbon hollow nanosphere powder.

[0051] (8) The obtained 70Zn30Co-ZIF nitrogen-doped porous carbon hollow nanosphere powder was mixed with selenium powder at a mass ratio of 1:1 and then placed in an argon protective atmosphere to be heated to 400℃ at a heating rate of 2℃ / min and held for 2h for annealing treatment to obtain zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder.

[0052] Figure 1 The image shown is a FESEM image of the amorphous 70Zn30Co-MOF nanospheres prepared in this embodiment. The nanospheres have a diameter of approximately 350 nanometers. Figure 2 The XRD diffraction pattern of the amorphous 70Zn30Co-MOF nanospheres prepared in this embodiment proves that the 70Zn30Co-MOF nanospheres are amorphous.

[0053] Figure 3 The image shown is a FESEM image of the 70Zn30Co-ZIF hollow nanospheres prepared in this embodiment. Figure 4 The XRD diffraction pattern of the 70Zn30Co-ZIF hollow nanospheres prepared in this embodiment proves that the sample was successfully transformed from an amorphous state to a ZIF structure.

[0054] Figure 5-6 The FESEM and TEM images of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in this embodiment show that the nanospheres have a hollow structure inside and the metal particles do not grow significantly under the coating of the porous carbon matrix. Figure 7 The XRD diffraction pattern of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in this embodiment is shown. The sample diffraction pattern corresponds one-to-one with the standard pattern.

[0055] Example 2

[0056] A method for preparing amorphous MOF-derived ZIF includes the following steps:

[0057] (1) Dissolve 0.2142g of zinc nitrate hexahydrate and 0.0233g of cobalt nitrate hexahydrate in 20mL of ethanol solution and sonicate to dissolve, forming solution A;

[0058] (2) Dissolve 0.1585g of 2,5-dihydroxyterephthalic acid in 20mL of ethanol solution and sonicate to form solution B;

[0059] (3) Slowly add solution A to solution B, stir thoroughly, transfer to a reaction vessel, place in a 160℃ oven for 10 hours, allow to cool naturally, centrifuge the product, wash with ethanol 3 times, and dry in a 60℃ oven to obtain amorphous 90Zn10Co-MOF powder.

[0060] (4) Disperse amorphous 90Zn10Co-MOF powder in a mixed solution of 5mL ethanol and 5mL deionized water to form suspension C;

[0061] (5) Dissolve 5g of 2-methylimidazole in a mixture of 15mL of ethanol and 15mL of deionized water, and add 424μL of triethylamine. Dissolve by sonication to form solution D.

[0062] (6) The suspension C was slowly added dropwise to the solution D. After stirring in a water bath at 70°C for 5 min, the product was centrifuged, washed three times with ethanol, and then dried in an oven at 60°C for 12 h to obtain 90Zn10Co-ZIF hollow nanosphere powder.

[0063] (7) 90Zn10Co-ZIF hollow nanosphere powder was placed in an argon protective atmosphere and heated to 700℃ at a heating rate of 2℃ / min and held for 2h to obtain nitrogen-doped porous carbon hollow nanosphere powder.

[0064] (8) The obtained 90Zn10Co-ZIF nitrogen-doped porous carbon hollow nanosphere powder was mixed with selenium powder at a mass ratio of 1:1 and then placed in an argon protective atmosphere to be heated to 400℃ at a heating rate of 2℃ / min and held for 2h for annealing to obtain zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder.

[0065] Figure 8 The image shown is a FESEM image of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in this embodiment. Figure 9 The XRD diffraction pattern of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres prepared in this embodiment is shown. The sample diffraction pattern corresponds one-to-one with the standard pattern.

[0066] Example 3

[0067] A method for preparing a sodium-ion battery includes the following steps:

[0068] (1) Zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder was mixed with conductive carbon black and binder polyvinylidene fluoride in a mass ratio of 8:1:1 and dissolved in 1-methyl-2-pyrrolidone. The mixture was shaken for 30 min to prepare an electrode slurry. The electrode slurry was then uniformly coated onto a copper foil current collector and dried in a vacuum drying oven at 60°C for 12 hours.

[0069] (2) The dried copper foil current collector was sliced ​​to make the working electrode, glass fiber was used as the separator, NaPF6 was used as the electrolyte, and sodium metal was used as the positive electrode material. The cells were assembled into a 2032 button cell in a glove box filled with argon gas.

[0070] After allowing the 2032 button cell to stand for 12 hours to fully wet the separator with electrolyte, its electrochemical performance was tested on a blue-light testing system. The test voltage range was 0.01V-3V vs Na. + / Na.

[0071] Figure 10 , 11 The image shows the electrochemical performance of a sodium-ion battery using the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere anode material prepared in this embodiment. This demonstrates that the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere anode material prepared in this embodiment has excellent rate performance and stable cycle performance.

[0072] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method of preparing an amorphous MOF-derived ZIF, characterized in that, Comprising the following steps: (1) adding zinc nitrate hexahydrate and cobalt nitrate hexahydrate into an ethanol solution, ultrasonic dissolving to form solution A; (2) adding 2,5-dihydroxyterephthalic acid into an ethanol solution, ultrasonic dissolving to form solution B; (3) slowly adding solution A into solution B, stirring thoroughly and then carrying out a solvothermal reaction, naturally cooling, centrifuging and washing the product and drying to obtain amorphous ZnCo-MOF powder; (4) dispersing the amorphous ZnCo-MOF powder in an ethanol aqueous solution to form suspension C; (5) dissolving 2-methylimidazole in an ethanol aqueous solution, adding triethylamine, stirring in a water bath and carrying out constant temperature treatment to form solution D; (6) slowly adding suspension C into solution D, stirring at constant temperature, centrifuging the product, washing with ethanol for several times and drying to obtain ZnCo-ZIF hollow nanosphere powder; (7) annealing the ZnCo-ZIF hollow nanosphere powder in an argon protective atmosphere to obtain ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder; (8) uniformly mixing the ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder with selenium powder, annealing in an argon protective atmosphere to obtain zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder.

2. The preparation method of the amorphous MOF derived ZIF according to claim 1, characterized in that: in the step (1), the concentration of zinc nitrate hexahydrate is 0.02-0.03 mol / L, and the concentration of cobalt nitrate hexahydrate is 0.01-0.02 mol / L; in the step (2), the concentration of 2,5-dihydroxyterephthalic acid is 0.03-0.04 mol / L; in the step (5), the concentration of 2-methylimidazole is 160-170 g / L.

3. The method of claim 1, wherein: in the step (3), the solvothermal reaction temperature is 120-160℃, the reaction time is 8-12 h, and the ethanol washing is 2-3 times.

4. The method of claim 1, wherein: in the step (6), the constant temperature stirring temperature is 60-80℃, the reaction time is 5-10 min, the drying temperature is 50-70℃, and the drying time is 6-12 h.

5. The method of claim 1, wherein: in the step (7), the annealing temperature is 600-800℃, the heating rate is 2-5℃ / min, and the holding time is 2-4 h.

6. The method of claim 1, wherein: in the step (8), the mass ratio of the ZnCo-ZIF nitrogen-doped porous carbon hollow nanosphere powder to selenium powder is 1:1-1:2, the annealing temperature is 300-600℃, the heating rate is 2-5℃ / min, and the holding time is 2-4 h.

7. The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder prepared by the preparation method of the amorphous MOF derived ZIF according to any one of claims 1-6.

8. The use of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanospheres powder according to claim 7, characterized in that: The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder is used for preparing a sodium ion battery negative electrode material.

9. A method of producing a sodium-ion battery, characterized by, Comprising the following steps: The zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder of claim 7 is uniformly mixed with conductive carbon black and polyvinylidene fluoride and dissolved in 1-methyl-2-pyrrolidone. The electrode slurry is prepared by shaking. The electrode slurry is then uniformly coated on copper foil and dried. The copper foil slices loaded with the electrode slurry are used as the negative electrode of the sodium-ion battery. The separator is glass fiber and the electrolyte is a binary electrolyte. The assembly is carried out in a glove box filled with argon gas to obtain the sodium-ion battery.

10. A method for preparing a sodium-ion battery according to claim 9, characterized in that: The mass ratio of the zinc selenide / cobalt selenide@nitrogen-doped porous carbon hollow nanosphere powder to conductive carbon black and polyvinylidene fluoride is 6:1:1 to 8:1:

1. The drying temperature is 50–70°C, and the drying time is 6–12 hours. The electrolyte is sodium hexafluorophosphate; The size of the working negative electrode of the sodium-ion battery is 10-12 mm; The positive electrode material of the sodium-ion battery is a sheet of metallic sodium.

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