A method for preparing carbon nanotube-modified copper-based MOF electrode material and its application

Abstract

This invention discloses a method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application, comprising: 1) dissolving a Cu2+ precursor and BTA hydrochloride separately in water to obtain two solutions; 2) slowly adding the copper-containing solution obtained in step 1) to the BTA hydrochloride solution and mixing, then adding concentrated ammonia to the mixed solution; 3) adding carbon nanotubes to the final solution obtained in step 2) and stirring; the amount of carbon nanotubes is 0.42 mmol to 1.2 mmol; 4) subjecting the solution obtained in step 3) to a hydrothermal reaction at a set time and temperature, washing the solid precipitated in the solution and drying it under a specific environment to obtain the carbon nanotube-modified copper-based MOF electrode material. This invention increases the conductivity and reactivity of the battery by adding carbon nanotubes to the copper-based MOF electrode. Through nanostructuring and compositing of the material, the interlayer spacing is also improved, thereby enhancing the cycle stability of the reaction.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries. Background Technology

[0002] In recent years, the demand for electrochemical energy storage devices with excellent performance such as high energy density, high power density, and high safety has been increasing in daily life and production. Rechargeable secondary batteries are considered key to solving the global energy crisis. Lithium-ion batteries currently dominate the high-energy-density commercial lithium-ion battery market due to their high energy conversion efficiency, long lifespan, and low self-discharge. However, the development and application of lithium-ion batteries have been somewhat constrained by safety issues associated with organic electrolytes and rising costs due to the declining lithium reserves. Aqueous magnesium-ion batteries (AMIBs), on the other hand, offer advantages such as high safety, environmental friendliness, low manufacturing cost, and a high theoretical volume ratio (Mg energy density of 3833 mAh cm⁻¹). -3 With advantages such as [missing information], and the absence of dendrite growth in rechargeable magnesium-ion batteries, they are highly suitable for large-scale applications. Therefore, aqueous magnesium-ion batteries are one of the sustainable and cost-effective energy storage systems. In metallurgical batteries (MIBs), the cathode has a significant impact on the overall electrochemical performance of the MIB. Numerous studies have shown that applying MOF materials and their derivatives to MIBs can overcome the cycle stability issues of cathode materials and achieve [missing information]. 2+ Rapid insertion / extraction improves the capacity, cycle life, and efficiency of magnesium-ion batteries.

[0003] MOF materials have been extensively studied in various fields, but existing synthesis methods are generally cumbersome, require stringent conditions, and produce small quantities per synthesis, making large-scale production difficult. This limits the widespread application of MOFs to some extent. Furthermore, existing MIB cathode materials are limited in variety and expensive. To meet the growing demand for magnesium-based energy storage, there is an urgent need to develop a low-cost, low-pollution MOF as the cathode active material for MIBs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing carbon nanotube-modified copper-based MOF electrode materials and their applications. By adding carbon nanotubes into the copper-based MOF electrode, the conductivity and reactivity of the battery are increased. Furthermore, the nano-sizing and composite of the materials also improves the interlayer spacing, thereby enhancing the cycle stability of the reaction.

[0005] The objective of this invention is achieved as follows: a method for preparing a carbon nanotube-modified copper-based MOF electrode material, comprising copper chloride, deionized water, carbon nanotubes, and BTA hydrochloride, including the following steps:

[0006] Step 1) Cu 2+ The precursor and BTA hydrochloride were dissolved in water to obtain two solutions;

[0007] Step 2) Slowly add the copper-containing solution obtained in Step 1) to the solution containing BTA hydrochloride and mix, then add concentrated ammonia to the mixed solution;

[0008] Step 3) Add carbon nanotubes to the solution obtained in step 2) and stir; the amount of carbon nanotubes is 0.42 mmol to 1.2 mmol.

[0009] Step 4) The solution obtained in Step 3) is subjected to a hydrothermal reaction at a set time and temperature. The solid precipitated in the solution is washed and dried under a specific environment to obtain a copper-based MOF electrode material modified with carbon nanotubes.

[0010] Further, in step 1), the Cu... 2+ The precursor is CuCl2, and the BTA hydrochloride is BTA·4HCl; the two solutions obtained contain Cu 2+ The concentrations of both BTA and BTA were 0.02 mol / L.

[0011] Furthermore, the final solution obtained in step 2) is alkaline.

[0012] Furthermore, in step 4), the hydrothermal reaction temperature is 60°C and the time is 12 hours; the obtained solid is dried in a vacuum environment.

[0013] Another aspect of the objective of this invention is achieved as follows: the application of a carbon nanotube-modified copper-based MOF electrode material in a magnesium-ion battery, wherein the electrode material obtained by the above-described method is used as the positive electrode, magnesium foil is used as the negative electrode, and magnesium ion solution is selected as the electrolyte, and the battery is assembled into a half-cell.

[0014] Furthermore, the magnesium foil is approximately 0.2 mm thick, and the magnesium ion solution used is a 4 mol / L MgCl2 solution.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention increases the conductivity and reactivity of the battery by adding carbon nanotubes into the copper-based MOF electrode. By nano-sizing and compositing the materials, the interlayer spacing of the materials is also improved, thereby improving the cycle stability of the reaction. The method for preparing organic cathode materials for magnesium-ion batteries is simple, low-cost, and environmentally friendly. It improves the cycle stability of magnesium anodes during cycling and the cycle capacity of aqueous magnesium-ion batteries, and reduces side reactions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a SEM image of a copper-based MOF material.

[0018] Figure 2 SEM image of copper-based MOF material modified with carbon nanotubes.

[0019] Figure 3 This is a voltage-to-capacity diagram of the first charge-discharge cycle of a magnesium-ion battery with a copper-based MOF electrode as the positive electrode.

[0020] Figure 4 The graph shows the specific capacity and coulombic efficiency of a magnesium-ion battery with a copper-based MOF electrode as the positive electrode after 100 cycles.

[0021] Figure 5 The diagram shows the voltage-to-capacity ratio of the magnesium-ion battery obtained in Example 2 during its first charge-discharge cycle.

[0022] Figure 6 The graph shows the specific capacity and coulombic efficiency of the magnesium-ion battery prepared in Example 2 after 100 cycles.

[0023] Figure 7 The diagram shows the voltage-to-capacity ratio of the magnesium-ion battery prepared in Example 3 during its first charge-discharge cycle.

[0024] Figure 8 The graph shows the specific capacity and coulombic efficiency of the magnesium-ion battery prepared in Example 3 after 100 cycles. Detailed Implementation

[0025] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: No carbon nanotubes added

[0027] The preparation method of copper-based MOF electrode materials and their application in magnesium-ion batteries are described in the following steps:

[0028] Preparation of copper-based MOF electrode materials:

[0029] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA·4 HCl powder in 10 ml of deionized water to obtain a BTA·4 HCl solution;

[0030] Step 2) Add CuCl2 solution to BTA·4HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0031] Step 3) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain copper-based MOF material.

[0032] SEM images of the fabricated copper-based MOF material are shown below. Figure 1 As shown, the copper-based MOF in this embodiment has good crystallinity.

[0033] Fabricate electrode plates and assemble the battery for performance testing:

[0034] The copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain the copper-based MOF electrode sheet.

[0035] The prepared MOF electrode sheet was used as the positive electrode, and 4M magnesium chloride was used as the electrolyte to assemble a half-cell in air. The fabricated half-cell was tested at Wuhan Landian System under a constant room temperature of 25℃. Performance test data are as follows: Figures 3-4 As shown, side reactions are present at the beginning, the coulombic efficiency is higher than 100%, and the cycle capacity stabilizes at only 50 mAh g. -1 .

[0036] Example 2: Nanotube addition amount was 1 mmol

[0037] A method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries is described below:

[0038] Preparation of carbon nanotube-modified copper-based MOF electrode materials

[0039] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA·4 HCl powder in 10 ml of deionized water to obtain a BTA·4 HCl solution;

[0040] Step 2) Add CuCl2 solution to BTA·4HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0041] Step 3) Add approximately 12 mg (1 mmol) of carbon nanotubes to the above grayish-black solution and stir for 30 minutes;

[0042] Step 4) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain carbon nanotube-modified copper-based MOF material.

[0043] SEM images of the carbon nanotube-modified copper-based MOF material are shown below. Figure 2 As shown, the copper-based MOF modified with carbon nanotubes in this embodiment exhibits good crystallinity.

[0044] Electrode sheets were fabricated and batteries were assembled for performance testing.

[0045] The carbon nanotube-modified copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain a carbon nanotube-modified copper-based MOF electrode sheet.

[0046] A half-cell was assembled in air using a carbon nanotube-modified MOF electrode as the positive electrode and 4M magnesium chloride as the electrolyte. The fabricated half-cell was tested at the Wuhan Landian System under constant temperature (25°C). Performance test data are as follows: Figures 5-6 As shown, the battery exhibits excellent cycle performance, with a coulombic efficiency consistently close to 100% and a cycle capacity reaching 75 mAh g. -1 .

[0047] Example 3: The amount of nanotubes added was 0.42 mmol;

[0048] A method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries is described below:

[0049] Preparation of carbon nanotube-modified copper-based MOF electrode materials

[0050] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA·4 HCl powder in 10 ml of deionized water to obtain a BTA·4 HCl solution;

[0051] Step 2) Add CuCl2 solution to BTA·4HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0052] Step 3) Add approximately 5 mg (0.42 mmol) of carbon nanotubes to the above grayish-black solution and stir for 30 minutes;

[0053] Step 4) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain carbon nanotube-modified copper-based MOF material.

[0054] Fabricate electrode plates and assemble the battery for performance testing:

[0055] The copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain the copper-based MOF electrode sheet.

[0056] The prepared MOF electrode sheet was used as the positive electrode, and 4M magnesium chloride was used as the electrolyte to assemble a half-cell in air. The fabricated half-cell was tested at Wuhan Landian System under a constant room temperature of 25℃. Performance test data are as follows: Figures 7-8 As shown, the battery exhibits superior cycle performance, with a coulombic efficiency consistently close to 100%, and the cycle capacity remains at 60 mAh g⁻¹. -1 above.

[0057] By comparison Figure 3 , 5 7. It can be seen that the copper-based MOF electrode sheet modified with carbon nanotubes has better cycling stability and the cycling capacity is stable at a high level. In contrast, the ordinary copper-based MOF electrode sheet and the copper-based MOF electrode sheets prepared in Examples 2 and 3 have higher initial cycling capacity, but more side reactions occur, resulting in a coulombic efficiency that is significantly higher than 100%, which is not stable enough.

[0058] By comparison Figure 4 , 6 Figures 8 show that the copper-based MOF electrode modified with carbon nanotubes has a high cycle capacity while maintaining a coulombic efficiency close to 100%. In contrast, the ordinary copper-based MOF electrode and the copper-based MOF electrode prepared in Examples 2 and 3 have slightly lower voltage and significantly higher coulombic efficiency than 100%, indicating that there are side reactions affecting the reaction process.

[0059] Example 4: Nanotube addition amount was 0.17 mmol;

[0060] A method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries is described below:

[0061] Preparation of carbon nanotube-modified copper-based MOF electrode materials

[0062] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA·4 HCl powder in 10 ml of deionized water to obtain a BTA·4 HCl solution;

[0063] Step 2) Add CuCl2 solution to BTA·4HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0064] Step 3) Add approximately 2 mg (0.17 mmol) of carbon nanotubes to the above grayish-black solution and stir for 30 minutes;

[0065] Step 4) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain carbon nanotube-modified copper-based MOF material.

[0066] Fabricate electrode plates and assemble the battery for performance testing:

[0067] The copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain the copper-based MOF electrode sheet.

[0068] Using the prepared MOF electrode as the positive electrode and 4M magnesium chloride as the electrolyte, a half-cell was assembled in air. The half-cell was tested at the Wuhan Landian System under constant room temperature of 25°C. Initially, side reactions were present during performance testing, with a coulombic efficiency exceeding 100%. However, the cycle capacity stabilized at only 55 mAh g⁻¹. -1 .

[0069] Example 5: The amount of nanotubes added was 1.2 mmol;

[0070] A method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries is described below:

[0071] Preparation of carbon nanotube-modified copper-based MOF electrode materials

[0072] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA·4 HCl powder in 10 ml of deionized water to obtain a BTA·4 HCl solution;

[0073] Step 2) Add CuCl2 solution to BTA·4HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0074] Step 3) Add approximately 14 mg (1.2 mmol) of carbon nanotubes to the above grayish-black solution and stir for 30 minutes;

[0075] Step 4) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain carbon nanotube-modified copper-based MOF material.

[0076] Fabricate electrode plates and assemble the battery for performance testing:

[0077] The copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain the copper-based MOF electrode sheet.

[0078] The prepared MOF electrode sheet was used as the positive electrode, and 4M magnesium chloride was used as the electrolyte to assemble a half-cell in air. The prepared half-cell was tested at Wuhan Landian System at a constant room temperature of 25°C. The performance test data was slightly lower than that of Example 2, but the battery cycle performance was better, with the coulombic efficiency always close to 100% and the cycle capacity maintained at 60 mAh g. -1 above.

[0079] Example 6: The amount of nanotubes added was 1.4 mmol;

[0080] A method for preparing a carbon nanotube-modified copper-based MOF electrode material and its application in magnesium-ion batteries is described below:

[0081] Preparation of carbon nanotube-modified copper-based MOF electrode materials

[0082] Step 1) Dissolve 0.6 mmol of CuCl2 in 10 ml of deionized water to obtain a blue solution, and dissolve 0.6 mmol of BTA•4 HCl powder in 10 ml of deionized water to obtain a BTA•4 HCl solution.

[0083] Step 2) Add CuCl2 solution to BTA•4 HCl solution and mix slowly to obtain a mixed solution with a small amount of flocculent matter. Then add concentrated ammonia solution dropwise to the mixed solution to obtain a gray-black solution.

[0084] Step 3) Add approximately 17 mg (1.4 mmol) of carbon nanotubes to the above grayish-black solution and stir for 30 minutes;

[0085] Step 4) Transfer the gray-black solution to a 100ml polytetrafluoroethylene-lined stainless steel autoclave and heat at 60℃ for 12h. Wash the product multiple times with acetone and distilled water, collect it after natural cooling to room temperature, and vacuum dry it at 60℃ for 24h to obtain carbon nanotube-modified copper-based MOF material.

[0086] Fabricate electrode plates and assemble the battery for performance testing:

[0087] The copper-based MOF material, conductive agent Ketjen black, and binder (PTFE) are thoroughly mixed and ground in a mass ratio of 6:3:1 to obtain a uniform electrode material. Then, the material is pre-dried in an oven at 60°C for 12 hours to obtain the copper-based MOF electrode sheet.

[0088] The prepared MOF electrode sheet was used as the positive electrode, and 4M magnesium chloride was used as the electrolyte to assemble a half-cell in air. The fabricated half-cell was tested at Wuhan Landian System under constant room temperature of 25°C. During performance testing, side reactions initially appeared, the coulombic efficiency initially exceeded 100%, and the cycle capacity was lower than 60 mAh g. -1 .

[0089] In summary, batteries assembled with carbon nanotubes at concentrations between 0.42 mmol and 1.2 mmol exhibited relatively superior cycle performance during testing, with coulombic efficiency consistently approaching 100% and cycle capacity maintained at 60 mAh g⁻¹. -1 The above is true. Battery performance was optimal, especially with a nanotube addition of 12 mg (1 mmol) (Example 2), where the coulombic efficiency remained close to 100% and the cycle capacity reached 75 mAh g⁻¹. If the nanotube addition exceeded or fell below this amount, battery performance began to decline, with the coulombic efficiency exceeding 100% and the cycle capacity falling below 60 mAh g⁻¹. -1 .

[0090] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a carbon nanotube-modified copper-based MOF electrode material, characterized in that, Includes the following steps: Step 1) Cu 2+ The precursor and BTA hydrochloride were dissolved in water to obtain two solutions; Step 2) Slowly add the copper-containing solution obtained in Step 1) to the solution containing BTA hydrochloride and mix, then add concentrated ammonia to the mixed solution; Step 3) Add carbon nanotubes to the solution obtained in step 2) and stir; the amount of carbon nanotubes is 0.42 mmol to 1.2 mmol. Step 4) The solution obtained in Step 3) is subjected to a hydrothermal reaction at a set time and temperature. The solid precipitated in the solution is washed and dried under a specific environment to obtain a copper-based MOF electrode material modified with carbon nanotubes.

2. The method for preparing a carbon nanotube-modified copper-based MOF electrode material according to claim 1, characterized in that, Step 1) The Cu 2+ The precursor is CuCl2, and the BTA hydrochloride is BTA·4HCl; the two solutions obtained contain Cu 2+ The concentrations of both BTA and BTA were 0.02 mol / L.

3. The method for preparing a carbon nanotube-modified copper-based MOF electrode material according to claim 1, characterized in that, Step 2) The final solution obtained is alkaline.

4. The method for preparing a carbon nanotube-modified copper-based MOF electrode material according to claim 1, characterized in that, In step 4), the hydrothermal reaction temperature is 60℃ and the time is 12 hours; the obtained solid is dried in a vacuum environment.

5. The application of a carbon nanotube-modified copper-based MOF electrode material in magnesium-ion batteries, characterized in that, Using the electrode material obtained by any one of claims 1 to 4 as the positive electrode, magnesium foil as the negative electrode, and magnesium ion solution as the electrolyte, a half-cell is assembled.

6. The application of the carbon nanotube-modified copper-based MOF electrode material according to claim 5 in a magnesium-ion battery, characterized in that, The magnesium foil is approximately 0.2 mm thick, and the magnesium ion solution used is a 4 mol / L MgCl2 solution.

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