Preparation method and application of CoMn bimetal organic framework compound

Abstract

The invention provides a preparation method and application of a CoMn bimetal organic framework compound. Comprising the following steps: 1, adding 4, 4 '-dipyridyl and 3-(chloromethyl) benzoic acid into DMF (Dimethyl Formamide), dissolving, and filtering to obtain a product; drying the product in vacuum to obtain a precursor; step 2, dissolving the precursor, cobalt chloride hexahydrate and manganese chloride tetrahydrate in a mixed solvent for reaction to obtain an intermediate product; and step 3, cooling the reaction kettle to room temperature to obtain the bimetallic organic framework compound CoMn-MOF. The CoMn-MOF is of a bimetallic structure of metal Co and metal Mn, and CoMn-MOF is synthesized by selecting a long-chain ligand rich in chloride ions. The CoMn-MOF is rich in nitrogen reduction sites, can ionize chloride ions and has a bimetallic channel structure, the structure can provide a large number of active sites, the transmission rate of the chloride ions and more chloride ions, and the conductivity of the material is improved. According to the method, the specific capacity, the cycling stability and the high safety of the chloride ion battery are effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of chloride ion battery energy, and in particular relates to a preparation method and application of a CoMn bimetallic organic framework compound. Background Art

[0002] With the growing demand for energy and the urgent need for sustainable energy storage solutions, the development of new battery technologies has become crucial. Lithium-ion batteries dominate the current energy storage field, but the limited resources, uneven distribution and rising costs of lithium have prompted researchers to look for alternative battery technologies. Chlorine is abundant on Earth and relatively cheap; chloride ions have a high redox potential and can theoretically achieve a higher energy density; compared with some traditional battery systems, chloride ion batteries may have better safety in some aspects. Therefore, chloride ion batteries can be used as a potential new energy storage technology.

[0003] Metal organic framework compounds have been widely reported and applied in the fields of supercapacitors, electrocatalysis and cationic batteries (Li, Na, Zn, etc.), but few have been reported in CIBs. The structure of MOF can be precisely controlled by selecting different metal ions and organic ligands. However, how to synthesize MOFs containing nitrogen reduction sites, ionizable chloride ions and bimetallic channel structures has not been reported so far. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of a CoMn bimetallic organic framework compound.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention relates to a method for preparing a bimetallic organic framework compound, comprising the following steps:

[0007] Step 1, adding a certain amount of 4,4'-bipyridine and 3-(chloromethyl)benzoic acid to 100-120 ml of DMF (N,N-dimethylformamide), after fully dissolving, pouring into a round-bottom flask, and heating and stirring for 12 hours under a nitrogen atmosphere and a temperature of 120° C., cooling to room temperature, filtering, washing, separating and collecting the product;

[0008] The product was placed in a vacuum drying oven at 60-90°C and dried to obtain the precursor 1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride, the structural formula of which is as follows:

[0009]

[0010] Step 2, dissolving a certain proportion of the precursor, cobalt chloride hexahydrate and manganese chloride tetrahydrate in a mixed solvent, and reacting in a reactor at 130-145° C. for 70-80 hours to obtain an intermediate product;

[0011] Step 3, cooling the reactor to room temperature at a rate of 4 to 6°C / hour to obtain green crystals, namely the bimetallic organic framework compound CoMn-MOF.

[0012] Preferably, in step 1, the usage ratio of 4,4'-bipyridine to 3-(chloromethyl)benzoic acid is 4:13.

[0013] Preferably, in step 1, the washing is specifically: washing the filtered product with hot N,N-dimethylformamide for 3 times.

[0014] Preferably, in step 2, the molar ratio of the precursor, cobalt chloride hexahydrate and manganese chloride tetrahydrate is 1:1:1.

[0015] Preferably, in step 2, the mixed solvent is a mixture of isopropanol, acetonitrile and dilute nitric acid; wherein, isopropanol (4 mL)-acetonitrile (4 mL)-dilute nitric acid (1 drop).

[0016] The present invention also relates to the application of the bimetallic organic framework compound prepared as above, and the bimetallic organic framework compound CoMn-MOF prepared by the above method of the present invention is used as a chloride ion battery material.

[0017] Preferably, the bimetallic organic framework compound CoMn-MOF is used as the positive electrode material, the metal lithium sheet is used as the negative electrode material, and the 1-butyl-1-methylpiperidinium chloride ionic liquid dissolved in polycarbonate is used as the electrolyte of the chloride ion battery to construct a chloride ion battery system with the MOF-based electrode material as the positive electrode. Under constant room temperature conditions, the electrochemical properties of the battery such as constant current charge and discharge behavior and cycle stability are tested.

[0018] The bimetallic organic framework compound CoMn-MOF prepared by the method of the present invention is a three-dimensional framework containing one-dimensional pores. The pores have the characteristics of uniform pore size distribution, moderate pore size, Cl atoms on the pore surface, etc., and are used to construct positive electrode materials for chloride ion batteries.

[0019] The present invention selects a new bimetallic structure of metal Co and metal Mn, and selects a long-chain ligand rich in chloride ions (1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride) to synthesize a bimetallic CoMn-MOF. The CoMn-MOF of the present invention is rich in nitrogen reduction sites, ionizable chloride ions and a bimetallic channel structure, which can provide a large number of active sites, a chloride ion transmission rate, and can also provide more chloride ions to increase the conductivity of the material. The present invention is a method for economically and effectively improving the specific capacity, cycle stability and high safety of chloride ion batteries.

[0020] The present invention has the following advantages:

[0021] (1) The high performance of the CoMn bimetallic organic framework compound (CoMn-MOF) prepared by the present invention is derived from the synergistic redox effect of Co, Mn metal nodes and N ligands, the unique channel structure of reversible Cl ion storage and the low chloride diffusion barrier, thereby forming a CoMn-MOF with a unique channel structure, which can optimize the electron transfer ability and ion adsorption ability, improve the electrical conductivity and material structure stability of the material, and thus improve the chloride ion rate performance and the long-cycle stability of the battery.

[0022] (2) The raw materials used in the method of the present invention are easily available, and the steps are simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a photo of the bimetallic CoMn-MOF in Example 1 under an optical microscope;

[0024] Figure 2 is a scanning electron microscope image of the bimetallic CoMn-MOF in Example 1;

[0025] Figure 3 is the X-ray diffraction pattern of the bimetallic CoMn-MOF in Example 1;

[0026] Figure 4 This is a charge and discharge curve diagram of the bimetallic CoMn-MOF electrode material in Example 1;

[0027] Figure 5 This is the rate curve of the bimetallic CoMn-MOF electrode material in Example 1. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0029] Example 1

[0030] This embodiment relates to the preparation of a bimetallic organic framework compound CoMn-MOF, and the specific steps are as follows:

[0031] Step 1, first, add 4g of 4,4'-bipyridine and 13g of 3-(chloromethyl)benzoic acid into a round-bottom flask, add 120mL of N,N-dimethylformamide to dissolve; introduce nitrogen into the mixed solution, and stir at 120°C for 12 hours; after the reaction is completed, cool to room temperature, filter the product, wash it with hot N,N-dimethylformamide 3 times, and place the product in a vacuum drying oven to dry, to obtain a precursor 1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride;

[0032] Step 2, add cobalt chloride hexahydrate (0.0237 g, 0.10 mmol), manganese chloride tetrahydrate (0.02 g, 0.10 mmol) and precursor 1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride (0.02 g, 0.10 mmol) into a 25 mL reaction kettle containing a mixed solvent of isopropanol (4 mL)-acetonitrile (4 mL)-dilute nitric acid (1 drop), and heat to 145° C. in a sealed state and maintain for 72 hours to obtain an intermediate product;

[0033] Step 3, cooling the temperature in the reactor to room temperature at a rate of 4 to 6°C / hour to obtain a bimetallic organic framework compound CoMn-MOF, see Figure 1 shown.

[0034] Example 2

[0035] An application of a bimetallic organic framework compound CoMn-MOF is as follows:

[0036] Step 1, take the bimetallic organic framework compound CoMn-MOF sample prepared in Example 1, add a conductive agent and a binder PVDF for grinding and mixing (wherein, CoMn-MOF accounts for 60% or more), after mixing to a certain degree, drip the solvent NMP and grind it thoroughly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on graphite paper (graphite paper thickness is 0.5-1mm, coating thickness is 75μm), and vacuum dried at 90-120°C for 24-48h, and then cut into a circular electrode piece with a diameter of 12mm as the positive electrode to obtain a chloride ion battery positive electrode piece.

[0037] Step 2: Take the chloride ion battery positive electrode obtained in step 1, and use a high-purity metal lithium sheet as the battery negative electrode, glass fiber paper (GF / D, Whatman) as a separator, and 1-butyl-1-methylpiperidinium chloride ionic liquid dissolved in polycarbonate as the electrolyte of the chloride ion battery to assemble a chloride ion battery.

[0038] The morphology of the bimetallic organic framework compound CoMn-MOF synthesized in Example 1 was characterized by SEM and XRD. Figure 2 and Figure 3 As shown in the figure, it can be seen that the crystal particles of the bimetallic organic framework compound CoMn-MOF are large and have good phase purity; see Figure 4 As shown in the figure, the information results show that the maximum discharge capacity of the bimetallic organic framework compound CoMn-MOF positive electrode material reaches 198.7mAh / g, and the capacity can be maintained at 127mAh / g after 200 charge and discharge cycles. Figure 5 As shown, after the bimetallic organic framework compound CoMn-MOF is charged and discharged with different currents, the higher the capacity retention rate, the less obvious attenuation occurs, indicating that the structure of the material is stable and not easy to collapse.

[0039] The method involved in the present invention selects a new bimetallic structure of metal Co and metal Mn, and selects a long-chain ligand rich in chloride ions (1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride) to synthesize a bimetallic CoMn-MOF. The CoMn-MOF of the present invention is rich in nitrogen reduction sites, ionizable chloride ions and a bimetallic channel structure, which can provide a large number of active sites, a chloride ion transmission rate, and can also provide more chloride ions to increase the conductivity of the material. The present invention is a method for economically and effectively improving the specific capacity, cycle stability and high safety of chloride ion batteries.

[0040] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for preparing a bimetallic organic framework compound, characterized in that: The following steps are involved: Step 1, adding a certain amount of 4,4'-bipyridine and 3-(chloromethyl)benzoic acid into 100-120 ml of DMF, after fully dissolving, pouring into a round-bottom flask, and heating and stirring at 120° C. for 12 hours under a nitrogen atmosphere, cooling to room temperature, filtering, washing, separating and collecting the product; The product was placed in a vacuum drying oven at 60-90° C. and dried to obtain the precursor 1,1'-bis(3-toluene)-[4,4'-bipyrazine]-1,1'-diammonium chloride; Step 2, dissolving a certain proportion of the precursor, cobalt chloride hexahydrate and manganese chloride tetrahydrate in a mixed solvent, and reacting in a reactor at 130-145° C. for 70-80 hours to obtain an intermediate product; Step 3, cooling the reactor to room temperature at a rate of 4 to 6°C / hour to obtain green crystals, namely the bimetallic organic framework compound CoMn-MOF.

2. The method for preparing a bimetallic organic framework compound according to claim 1, characterized in that: In step 1, the usage ratio of 4,4'-bipyridine and 3-(chloromethyl)benzoic acid is 4:

13.

3. The method for preparing a bimetallic organic framework compound according to claim 1, characterized in that: In step 1, the washing specifically comprises: washing the filtered product with hot N,N-dimethylformamide for 3 times.

4. The method for preparing a bimetallic organic framework compound according to claim 1, characterized in that: In step 2, the molar ratio of the precursor, cobalt chloride hexahydrate and manganese chloride tetrahydrate is 1:1:

1.

5. The method for preparing a bimetallic organic framework compound according to claim 1, characterized in that: In step 2, the mixed solvent is a mixture of isopropanol, acetonitrile and dilute nitric acid.

6. An application of a bimetallic organic framework compound, characterized in that: The bimetallic organic framework compound CoMn-MOF prepared according to claim 1 is used as a chloride ion battery material.

7. The use of the bimetallic organic framework compound as claimed in claim 6, characterized in that: The bimetallic organic framework compound CoMn-MOF is used as the positive electrode material, the metal lithium sheet is used as the negative electrode material, and the 1-butyl-1-methylpiperidinium chloride ionic liquid dissolved in polycarbonate is used as the electrolyte of the chloride ion battery to construct a chloride ion battery system with MOF-based electrode material as the positive electrode.

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