Sea urchin-like hollow series of metal organic framework structures and methods of making and using the same

Abstract

The application discloses a sea urchin-shaped hollow series metal organic framework structure and a preparation method and application thereof, and the method comprises the following steps: uniformly dispersing precursors MOFs and organic ligands in N,N-dimethylformamide, then transferring to a high-pressure reaction kettle, and placing the reaction kettle in a constant-temperature air drying box for reaction; after the reaction is completed, centrifuging, washing and drying the product to obtain the sea urchin-shaped hollow series metal organic framework structure. The sea urchin-shaped hollow series metal organic framework structure is placed in a tube furnace in an argon atmosphere, high-temperature annealing carbonization is performed to form a sea urchin-shaped hollow series Co-MOF-74@C structure. The sea urchin-shaped hollow series Co-MOF-74@C structure is mixed with selenium powder, then annealing is performed under the protection of an argon atmosphere to obtain a sea urchin-shaped hollow series Co-MOF-74 metal selenide@carbon heterojunction. The sea urchin-shaped hollow series Co-MOF-74 metal selenide@carbon heterojunction can be used for preparing a sodium ion battery negative electrode material, and the electrochemical performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of micro / nano composite material synthesis technology, specifically to sea urchin-like hollow metal-organic framework structures, their preparation methods, and applications. Background Technology

[0002] In recent years, the ever-increasing demand for fossil fuels has led to a decline in energy storage. Lithium-ion batteries, due to their high energy density, excellent rate performance, and relatively good cycle performance, have been widely used in many fields. However, the scarcity of lithium resources and the continuous rise in lithium prices hinder the widespread use of lithium-ion batteries in the future. Sodium-ion batteries, on the other hand, have attracted widespread attention due to their high energy density, rapid ion transport kinetics in the electrolyte, safety and environmental friendliness, and low production costs, and are considered the most promising next-generation energy storage system.

[0003] However, the large radius of sodium ions leads to low reversible specific capacity, poor rate performance, and poor cycle stability. Metal-organic frameworks (MOFs) are crystalline materials with tunable porosity and structure, formed by the coordination of transition metal ions or clusters with organic ligands. Porous carbon composites can be synthesized from MOFs through a simple annealing process, and the resulting composites always inherit the unique structure of MOFs. They are widely used in electrochemical energy storage, solar energy conversion, electromagnetic wave absorption, catalysis, and drug delivery. The electrochemical reactions of transition metal selenides are mostly alloying reactions, resulting in high theoretical specific capacity. However, during the ion insertion / extraction process, the electrode material undergoes significant volume changes, easily causing the electrode material to detach from the current collector, greatly reducing battery efficiency and lifespan. Summary of the Invention

[0004] The purpose of this invention is to provide a series of sea urchin-like hollow metal-organic framework structures, their preparation methods, and applications, which can combine sea urchin-like hollow structures with transition metal selenides and be used in sodium-ion battery anode materials.

[0005] In one aspect of the present invention, a method for preparing a series of sea urchin-like hollow metal-organic framework structures is provided. According to an embodiment of the present invention, the method includes the following steps:

[0006] (1) The precursor MOFs and organic ligands are uniformly dispersed in N,N-dimethylformamide to form a mixture;

[0007] (2) Transfer the mixture to the reaction vessel and place the reaction vessel in a constant temperature drying oven for reaction;

[0008] (3) After the reaction was completed, the product was centrifuged, washed several times, and then dried in an oven to obtain a series of hollow metal-organic framework structures resembling sea urchins.

[0009] In addition, the preparation method of the sea urchin-like hollow metal-organic framework structure according to the above embodiments of the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, in step (1), the precursor MOFs are ZIF-67, the organic ligands are 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid or 3,3”-dihydroxy-2',5'-dimethyl-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid, the mass ratio of the precursor to the organic ligand is 1:1-1:2; the concentration of the mixture is 0.27-0.67 g / L; and the mixture is completely dissolved by ultrasound.

[0011] The precursor ZIF-67 is prepared as follows: cobalt nitrate hexahydrate is dissolved in deionized water to form solution A1, and hexadecyltrimethylammonium bromide (CTAB) and 2-methylimidazole are dissolved in deionized water to form solution B1. Solution A1 is slowly added dropwise to solution B1, and the reaction is carried out for 16 min. The product is then centrifuged and washed with deionized water and anhydrous ethanol to obtain ZIF-67. After drying in an oven at 80-100℃ for 10-24 h, ZIF-67 powder is obtained.

[0012] In some embodiments of the present invention, in step (2), the temperature of the constant temperature drying oven is 70-130°C, that is, the reaction temperature is 70-130°C and the reaction time is 600-750 min.

[0013] In some embodiments of the present invention, in step (3), the product is separated at a rotation speed of 500-3000 r / min and a centrifugation time of 2-15 min; it is washed multiple times with ethanol and water; the oven drying temperature is 70-120℃ and the drying time is 10-24 h.

[0014] In another aspect of the present invention, the present invention provides a method for preparing the aforementioned sea urchin-shaped hollow metal-organic framework structure, thereby obtaining the sea urchin-shaped hollow metal-organic framework structure.

[0015] In another aspect of the invention, a series of sea urchin-shaped hollow Co-MOF-74@C structures is proposed. According to an embodiment of the invention, the aforementioned sea urchin-shaped hollow metal-organic framework structure is placed in a tube furnace under an argon atmosphere and subjected to high-temperature annealing and carbonization to form the sea urchin-shaped hollow Co-MOF-74@C structure.

[0016] In addition, the sea urchin-shaped hollow Co-MOF-74@C structure according to the above embodiments of the present invention may also have the following additional technical features:

[0017] In some embodiments of the present invention, the annealing temperature is 600-900°C, the heating rate is 2°C / min, and the holding time is 1-3h.

[0018] In another aspect of the invention, a sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction is proposed. According to an embodiment of the invention, the aforementioned sea urchin-shaped hollow Co-MOF-74@C structure is mixed with selenium powder, and then annealed under an argon atmosphere to obtain the sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction.

[0019] In addition, the sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction according to the above embodiments of the present invention may also have the following additional technical features:

[0020] In some embodiments of the present invention, the mass ratio of the sea urchin-shaped hollow Co-MOF-74@C structure to selenium powder is 1:0.5 to 1:2, the annealing temperature is 300 to 500°C, the heating rate is 2°C / min, and the holding time is 1 to 3 hours.

[0021] In another aspect of the invention, the invention proposes to use the aforementioned urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction for the preparation of high-performance sodium-ion battery anode materials.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1) The urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction prepared in this invention utilizes both the high specific capacity of Co-containing metal selenides and the large specific surface area, low density, and high loading capacity of the hollow metal-organic framework structure. This mitigates the structural damage caused by sodium ions during charge and discharge, thereby improving the electrochemical performance of sodium-ion batteries, such as cycle life and rate performance. Furthermore, the metal selenide is uniformly distributed within the porous carbon, significantly reducing its volume expansion during sodium ion storage. These characteristics effectively improve the rate performance and cycle performance of sodium-ion batteries and hold promise as an ideal anode material for next-generation energy storage batteries.

[0024] 2) The sea urchin-shaped hollow Co-MOF-74 series prepared by this invention (e.g.) and Compared to other MOFs, it has advantages such as larger pore size and larger specific surface area. These features can provide more ion diffusion channels and more sites for sodium ions, which greatly improves the performance of the battery.

[0025] 3) The sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterostructure prepared by this invention is first carbonized at high temperature under a protective atmosphere, and then annealed after being mixed with selenium powder. The high-temperature carbonization causes the metal nodes of the metal-organic framework to form dispersed carbon-coated metal nanoparticles in situ, and the organic ligand ends to form porous carbon structures in situ, which restricts the growth of metal particles. This also ensures that the cobalt selenide in the subsequent selenization process will not agglomerate and grow. Therefore, the Co-containing metal selenide will be uniformly distributed in the hollow structure.

[0026] 4) The sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction prepared by this invention can be further obtained by doping different transition metal elements to obtain different metal selenide@carbon heterojunction materials, which expands the application field of metal selenide@carbon heterojunction materials and provides more electrode active materials for efficient electrochemical energy storage applications, which has great practical value.

[0027] 5) The material prepared in this invention has a hollow structure, which has many advantages over solid materials: ① The thin shell and internal cavity can shorten the electron / ion transport path; ② The large effective specific surface area can increase the contact area between the electrode material and the electrolyte; ③ The large effective specific surface area also provides more ion storage active sites; ④ The hollow cavity can reduce the volume expansion caused by insertion / extraction. These advantages make this type of material exhibit extremely excellent performance.

[0028] 6) This invention further expands the application field of MOFs materials. Utilizing the high specific surface area, high porosity and tunable structure of MOFs materials, they have greater practical application value in separation, catalysis, sensing and energy storage and other fields. Attached Figure Description

[0029] Figure 1 These are scanning electron microscope images of the sea urchin-shaped hollow single-shell Co-MOF-74-II prepared in Example 1 of this invention;

[0030] Figure 2 This is a transmission electron microscope image of the sea urchin-shaped hollow single-shell Co-MOF-74-II prepared in Example 1 of this invention;

[0031] Figure 3 This is the XRD diffraction pattern of the sea urchin-shaped hollow single-shell Co-MOF-74-II prepared in Example 1 of this invention;

[0032] Figure 4 These are scanning electron microscope images of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅲ prepared in Example 2 of this invention;

[0033] Figure 5This is a transmission electron microscope image of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅲ prepared in Example 2 of this invention;

[0034] Figure 6 This is the XRD diffraction pattern of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅲ prepared in Example 2 of this invention;

[0035] Figure 7 These are scanning electron microscope images of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅱ@C prepared in Example 3 of this invention;

[0036] Figure 8 These are transmission electron microscope images of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅱ@C prepared in Example 3 of this invention;

[0037] Figure 9 This is the XRD diffraction pattern of the sea urchin-shaped hollow single-shell Co-MOF-74-Ⅱ@C prepared in Example 3 of this invention;

[0038] Figure 10 This is a scanning electron microscope image of the sea urchin-shaped hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction prepared in Example 4 of this invention;

[0039] Figure 11 This is a transmission electron microscope image of the sea urchin-shaped hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction prepared in Example 4 of this invention;

[0040] Figure 12 This is the XRD diffraction pattern of the sea urchin-shaped hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction prepared in Example 4 of the present invention.

[0041] Figure 13 These are images showing the electrochemical performance of the sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction prepared in Example 5 applied to a sodium-ion battery. Detailed Implementation

[0042] 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.

[0043] Example 1

[0044] The preparation method of sea urchin-like hollow single-shell Co-MOF-74-Ⅱ powder includes the following steps:

[0045] (1) Take 6 mg ZIF-67 and 6 mg 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid (abbreviated as H4dobpdc) and disperse them evenly in 40 ml DMF to form a mixture. Sonicate until completely dissolved. Then transfer the mixture to a 50 ml high-pressure reactor and place the reactor in a 110℃ constant temperature drying oven for 750 min.

[0046] (2) After the reaction was completed, the product was centrifuged at 3000 r / min for 3 min to collect the sample, and washed three times with water and ethanol. Finally, it was placed in a vacuum drying oven at 80℃ and dried for 12 h to obtain hollow single-shell Co-MOF-74-Ⅱ powder.

[0047] Figure 1 The image shows a scanning electron microscope (SEM) image of the prepared hollow single-shell Co-MOF-74-Ⅱ. The image shows that the hexahedrons are evenly distributed and the surface has a urchin-like villous structure. Figure 2 This is a transmission electron microscope image of Co-MOF-74-II, which shows that it has a hollow single-shell structure with hollow particles in the middle. Figure 3 The XRD diffraction pattern shows that the hollow single-shell Co-MOF-74-Ⅱ structure was successfully prepared in Example 1, and its diffraction pattern corresponds one-to-one with the standard spectrum.

[0048] Example 2

[0049] The preparation method of sea urchin-like hollow single-shell Co-MOF-74-Ⅲ cubic powder includes the following steps:

[0050] (1) Take 6 mg ZIF-67 and 6 mg 3,3”-dihydroxy-2',5'-dimethyl-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid (abbreviated as H4dotpdc) and disperse them evenly in 40 ml DMF to form a mixture. Sonicate until completely dissolved. Then transfer the mixture to a 50 ml reaction vessel and place the reaction vessel in a 110℃ constant temperature drying oven for 750 min.

[0051] (2) After the reaction was completed, the product was collected by centrifugation at 3000 r / min for 3 min, washed three times with water and ethanol, and finally dried in a vacuum drying oven at 80℃ for 12 h to obtain single-shell hollow Co-MOF-74-Ⅲ powder.

[0052] Figure 4 The image shows a scanning electron microscope (SEM) image of the prepared hollow single-shell Co-MOF-74-Ⅲ. It can be seen that Co-MOF-74-Ⅲ consists of urchin-like nanoparticles on the surface, with a size of approximately 500 nm. Figure 5 This is a transmission electron microscope image of a hollow monolayer Co-MOF-74-Ⅲ, which shows that it has a hollow monolayer structure. Figure 6The XRD diffraction pattern shows that the hollow Co-MOF-74-Ⅲ structure was successfully prepared in Example 2, and its diffraction pattern corresponds one-to-one with the standard spectrum.

[0053] Example 3

[0054] The preparation method of the sea urchin-like hollow single-shell Co-MOF-74-Ⅱ@C structure includes the following steps:

[0055] The hollow single-shell Co-MOF-74-Ⅱ powder from Example 1 was first placed in a tube furnace under an argon atmosphere and annealed at a high temperature of 700℃, with a heating rate of 2℃ / min and a holding time of 2h, to obtain a sea urchin-like hollow single-shell Co-MOF-74-Ⅱ@C structure.

[0056] Figure 7 This is a scanning electron microscope image of a sea urchin-like hollow single-shell Co-MOF-74-Ⅱ@C. Figure 8 This is a transmission electron microscope image of a hollow, urchin-like single-shell Co-MOF-74-Ⅱ@C. Figure 9 It is the XRD diffraction pattern of a hollow, single-shelled, sea urchin-like Co-MOF-74-Ⅱ@C.

[0057] Example 4

[0058] A method for preparing a sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterostructure includes the following steps:

[0059] The sample annealed at 700℃ in Example 3 was mixed with selenium powder at a mass ratio of 1:2 and vortexed. The mixture was then annealed in a tube furnace under argon atmosphere at a high temperature of 400℃, a heating rate of 2℃ / min, and a holding time of 2h, yielding a sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterostructure.

[0060] Figure 10 This is a scanning electron microscope image of a sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterostructure. Figure 11 This is a transmission electron microscope image of a sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterostructure. Figure 12 The image shows the XRD diffraction pattern of a sea urchin-shaped hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction, indicating that it is CoSe2@C.

[0061] Example 5

[0062] A method for preparing sodium-ion battery anode materials includes the following steps:

[0063] The sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction from Example 4, along with the binder polyvinylidene fluoride and conductive carbon black, were uniformly mixed in a mass ratio of 8:1:1 and dissolved in 1-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was then uniformly coated onto a copper foil current collector and dried in a vacuum drying oven at 80°C for 24 hours. The dried copper foil current collector was then sliced ​​to form the working electrode, which is the negative electrode material for sodium-ion batteries.

[0064] In an argon-filled glove box, a CR2032 sodium-ion half-cell was assembled sequentially with the following components: negative electrode shell, sodium metal counter electrode, separator, electrolyte, working electrode sheet, gasket, spring sheet, and positive electrode shell. The sodium-ion negative electrode material prepared in Example 5 was used as the working electrode, glass fiber as the separator, and NaCF3SO3 as the electrolyte. After standing for 12 hours to allow the electrolyte to fully wet the separator, the electrochemical performance was tested using a blue electrode testing system.

[0065] Figure 13 The image shows the electrochemical performance of a sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction as an anode material for sodium-ion batteries. Its specific capacity reaches 250 mAh / g at a current density of 5 A / g and 200 mAh / g at a current density of 10 A / g, while the theoretical specific capacity of traditional graphite anodes is only 35 mAh / g. Furthermore, it maintains approximately 300 mAh / g after 1000 cycles at a current density of 2 A / g with no significant capacity decay, demonstrating its excellent rate capability and cycle performance. Therefore, the sea urchin-like hollow single-shell Co-MOF-74-II metal selenide@carbon heterojunction prepared in this invention can be used as an anode material for high-performance sodium-ion batteries.

[0066] The above description is merely an example and illustration of the structure 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 for preparing urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction, characterized in that, Includes the following steps: (1) The precursor MOFs and organic ligands are uniformly dispersed in N,N-dimethylformamide to form a mixture, wherein the precursor MOFs are ZIF-67; (2) Transfer the mixture to the reaction vessel and place the reaction vessel in a constant temperature drying oven for reaction; (3) After the reaction was completed, the product was centrifuged, washed several times, and then dried in an oven to obtain a series of hollow metal-organic framework structures resembling sea urchins. (4) The sea urchin-shaped hollow series metal-organic framework structure is placed in a tube furnace in an argon atmosphere and subjected to high-temperature annealing and carbonization to form a sea urchin-shaped hollow series Co-MOF-74@C structure, wherein the annealing temperature is 600~900℃, the heating rate is 2℃ / min, and the holding time is 1~3 h. (5) The sea urchin-shaped hollow Co-MOF-74@C structure is mixed with selenium powder and then annealed under argon atmosphere to obtain sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction.

2. The method for preparing the urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction according to claim 1, characterized in that: In step (1), the organic ligand is 3,3'-dihydroxy-4,4'-biphenylcarboxylic acid or 3,3”-dihydroxy-2',5'-dimethyl-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid, and the mass ratio of the precursor to the organic ligand is 1:1 to 1:2; the concentration of the mixture is 0.27 to 0.67 g / L; the mixture is completely dissolved by ultrasound.

3. The method for preparing the urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction according to claim 1, characterized in that: In step (2), the temperature of the constant temperature drying oven is 70-130℃ and the reaction time is 600-750 min.

4. The method for preparing the urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction according to claim 1, characterized in that: In step (3), the product is separated at a speed of 500-3000 r / min and a centrifugation time of 2-15 min; it is washed multiple times with ethanol and water; the oven drying temperature is 70-120℃ and the drying time is 10-24 h.

5. The method for preparing the urchin-like hollow Co-MOF-74 metal selenide@carbon heterojunction according to claim 1, characterized in that: In step (5), the mass ratio of the sea urchin-shaped hollow Co-MOF-74@C structure to the selenium powder is 1:0.5 to 1:2, the annealing temperature is 300 to 500℃, the heating rate is 2℃ / min, and the holding time is 1 to 3 h.

6. A method for preparing a hollow series of Co-MOF-74 metal selenide@carbon heterojunctions as described in any one of claims 1-5.

7. The sea urchin-shaped hollow Co-MOF-74 metal selenide@carbon heterojunction as described in claim 6 is used to prepare high-performance sodium-ion battery anode materials.

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