Preparation method of vanadium-based sulfide heterostructure and application of vanadium-based sulfide heterostructure in magnesium secondary battery

Abstract

The invention discloses a vanadium-based sulfide heterostructure preparation method, which comprises: 1) respectively grinding a copper source, a vanadium source and a sulfur source through a mortar, adding into deionized water, uniformly stirring at a room temperature, and adjusting the pH value of the system to 10-13 to obtain a mixed solution; 2) transferring the mixed solution into deionized water, uniformly mixing, and carrying out heating reaction; and after the reaction is finished, cooling, centrifuging and drying to obtain the vanadium-based sulfide heterostructure. CuS is introduced into Cu3VS4 by a hydrothermal method to construct a heterostructure, the electron mobility of the material is improved, the conductivity and magnesium ion diffusion power are further improved, the specific capacity of the prepared Cu3VS4 / CuS is excellent, and the capacity can reach 200 mAh / g after activation; the preparation method is simple and convenient in process, wide in applicability, high in safety performance, capable of accurately regulating and controlling the phase content, low in reaction raw material and equipment requirements and capable of being popularized and applied on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials technology, specifically relating to a vanadium-based sulfide heterostructure, its preparation method, and its application in magnesium secondary batteries. Background Technology

[0002] Lithium-ion batteries (LIBs) possess advantages such as high operating voltage, low self-discharge rate, and no memory effect, making them the most widely used rechargeable batteries in electronic products and electric vehicles. However, they face numerous challenges, including the scarcity of lithium resources and the safety concerns associated with lithium dendrite formation. Therefore, developing novel electrochemical energy storage devices to alleviate the pressure on lithium-ion batteries is of great significance. To date, numerous researchers have developed a series of novel electrochemical energy storage devices, including Na-ion batteries, K-ion batteries, Mg-ion batteries, Zn-ion batteries, Ca-ion batteries, and Al-ion batteries.

[0003] Magnesium-ion batteries (MIBs), as one of the representatives of multivalent ion batteries, have emerged as a rising star in recent years and have received extensive research. In the periodic table, magnesium and lithium are diagonally opposite each other, and both have similar chemical properties. Compared to lithium, magnesium has advantages such as abundant resources (2.3% of the Earth's crust reserves are 1045 times that of lithium (0.0022%)), simple synthesis processes, and lower costs. Furthermore, the divalent nature of magnesium ions allows them to carry and store more charge, and magnesium-ion batteries have a higher volumetric capacity (3833 mAh / cm³). -3 Most importantly, magnesium is relatively stable in air as a negative electrode and does not form dendrites, which greatly improves safety performance; therefore, the development of high-performance magnesium-ion batteries has great potential.

[0004] Although magnesium-ion batteries have considerable development potential, their cathode, anode, and electrolyte still face a series of challenges. For example, magnesium ions have a small ionic radius and high charge density, making cathode materials prone to binding with solvents, leading to severe solvation. Only a few cathode materials can effectively achieve reversible insertion / extraction of magnesium ions. Sulfides are considered the most promising cathode materials for magnesium-ion batteries due to their unique properties. Among them, Cu3VS4, a typical vanadium-based sulfide, possesses advantages such as three-dimensional ion channels conducive to magnesium ion diffusion, multi-electron reaction potential, and good diffusion kinetics, leading to its widespread adoption and application in magnesium-ion battery cathode materials. However, due to limited research on this type of compound in magnesium-based batteries, problems such as unclear electrochemical mechanisms, low operating voltage, and poor conductivity remain. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a method for preparing vanadium-based sulfide heterostructures, aiming to address the problems of poor conductivity in existing cathode materials used in magnesium-ion batteries and poor reversible insertion / extraction migration of magnesium in magnesium-ion batteries.

[0006] The present invention also provides the application of the vanadium-based sulfide heterostructure in magnesium secondary batteries.

[0007] The objective of this invention is achieved through the following technical solution: A method for preparing a vanadium-based sulfide heterostructure includes the following steps: 1) Grind the copper source, vanadium source and sulfur source separately in a mortar and pestle, add them to deionized water, stir evenly at room temperature, and adjust the pH of the system to 10-13 to obtain a mixed solution; 2) Transfer the mixed solution obtained in step 1) to deionized water, mix thoroughly, and then heat to react. After the reaction is complete, cool, centrifuge, and dry to obtain a vanadium-based sulfide heterostructure.

[0008] In some specific embodiments, the molar ratio of copper, vanadium and sulfur is 3:1:(6-20).

[0009] In some specific embodiments, the copper source is any one or a combination of at least two of copper fluoride, copper chloride, copper bromide, copper nitrate, copper sulfate, copper carbonate, copper oxalate, copper acetate, basic copper carbonate, copper hydroxide, copper oxide, copper sulfide, and copper acetylacetonate.

[0010] In some specific embodiments, the vanadium source is any one or a combination of at least two of ammonium metavanadate, vanadium acetylacetonate, and sodium orthovanadate.

[0011] In some specific embodiments, the sulfur source is any one or a combination of at least two of thioacetamide, thiourea, and L-cysteine.

[0012] In some specific embodiments, the volume of the mixed solution in step 2) accounts for 1 / 2 to 3 / 4 of the total volume of the reaction system.

[0013] In some specific embodiments, the process conditions for the heating reaction in step 2) are: reacting at a temperature of 160-230°C for 1-3 days.

[0014] In some specific embodiments, the centrifugation process conditions in step 2) are as follows: take the cooled reaction solution and place it in a centrifuge tube, centrifuge it 2-5 times alternately with deionized water and ethanol, centrifuge at a speed of 8000-12000 rpm, and each centrifugation time is 2-10 min, and remove the supernatant.

[0015] In some specific embodiments, the drying process conditions are: drying in a vacuum oven at 50-70℃ for 10-15 hours.

[0016] As part of the same inventive concept, this invention also provides the application of the vanadium-based sulfide heterostructure prepared by the aforementioned method in magnesium secondary batteries.

[0017] Compared with the prior art, the present invention has at least the following advantages: 1) The preparation method provided by the present invention introduces CuS into Cu3VS4 to construct a heterostructure by hydrothermal method, thereby improving the electron mobility of the material, and thus improving the conductivity and magnesium ion diffusion kinetics; the prepared Cu3VS4 / CuS exhibits excellent specific capacity, and the capacity after activation can reach 200 mAh / g.

[0018] 2) The preparation method of the present invention is simple, widely applicable, safe, and allows for precise control of phase content. It also has low requirements for reaction raw materials and equipment, and can be promoted and applied on a large scale. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 The XRD result of the copper thiovanadate heterostructure cathode material with a pH of 11 provided in Example 3 of the present invention is shown. Figure 2 The XRD result of the copper thiovanadate heterostructure cathode material with a pH of 12 provided in Example 1 of this invention; Figure 3 The XRD result of the copper thiovanadate heterostructure cathode material with a pH of 13 provided in Example 4 of this invention; Figure 4 This is a SEM image of the copper thiovanadate heterostructure cathode material with a pH of 11 provided in Example 3 of the present invention. Figure 5 This is a SEM image of the copper thiovanadate heterostructure cathode material with a pH of 12 provided in Example 1 of the present invention. Figure 6 This is a SEM image of the copper thiovanadate heterostructure cathode material with a pH of 13 provided in Example 4 of the present invention. Figure 7 The electrochemical performance curve of the copper thiovanadate heterostructure cathode material with a pH of 12 provided in Example 1 of the present invention at a current density of 200 mA / g. Figure 8The electrochemical performance curve of the copper thiovanadate cathode material provided in Comparative Example 1 of this invention at a current density of 50 mA / g. Figure 9 The electrochemical performance curve of the copper sulfide cathode material provided in Comparative Example 2 of this invention is shown at a current density of 200 mA / g. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0022] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values ​​listed herein include the endpoints of the range and all integers and fractions within that range.

[0023] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0024] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0025] Example 1 The method for preparing vanadium-based sulfide heterostructures provided in this embodiment includes the following steps: 1) Grind the copper source, vanadium source and sulfur source separately in a mortar and pestle and add them to 60 ml of deionized water. The molar ratio of copper, vanadium and sulfur is 3:1:12. After stirring evenly at room temperature, adjust the pH of the system to 12 with ammonia water to obtain a mixed solution. The copper source is copper chloride, the vanadium source is ammonium metavanadate and the sulfur source is thiourea. 2) Transfer the mixed solution obtained in step 1) into a 100ml reaction vessel liner and place it into the reaction vessel. Heat to 200℃ and react at 200℃ for 1 day. After the reaction is complete, cool to room temperature to obtain the reaction solution; 3) Take the cooled reaction solution and place it in a centrifuge tube. Centrifuge it three times with deionized water and ethanol alternately at a speed of 10,000 rpm for 8 minutes each time. Remove the supernatant. Then dry the centrifuged solid in a vacuum oven at 60°C for 12 hours to obtain the vanadium-based sulfide heterostructure.

[0026] Example 2 The method for preparing vanadium-based sulfide heterostructures provided in this embodiment includes the following steps: 1) Grind the copper source, vanadium source and sulfur source separately in a mortar and pestle and add them to 60 ml of deionized water. The molar ratio of copper, vanadium and sulfur is 3:1:12. After stirring evenly at room temperature, adjust the pH of the system to 10 with ammonia water to obtain a mixed solution. The copper source is copper nitrate, the vanadium source is ammonium metavanadate and the sulfur source is thiourea. 2) Transfer the mixed solution obtained in step 1) into a 100ml reaction vessel liner and place it into the reaction vessel. Heat to 200℃ and react at 200℃ for 2 days. After the reaction is complete, cool to room temperature to obtain the reaction solution; 3) Take the cooled reaction solution and place it in a centrifuge tube. Centrifuge it three times with deionized water and ethanol alternately at a speed of 10,000 rpm for 8 minutes each time. Remove the supernatant. Then dry the centrifuged solid in a vacuum oven at 60°C for 12 hours to obtain the vanadium-based sulfide heterostructure.

[0027] Example 3 The preparation method of the vanadium-based sulfide heterostructure provided in this embodiment is basically the same as that in Example 1, except that in step 1), ammonia water is used to adjust the system and maintain the pH value of the system at 11.

[0028] Example 4 The preparation method of the vanadium-based sulfide heterostructure provided in this embodiment is basically the same as that in Example 1, except that in step 1), ammonia water is used to adjust the system and maintain the pH value of the system at 13.

[0029] Comparative Example 1 This comparative example provides a method for preparing vanadium-based sulfide Cu3VS4 for magnesium-ion batteries.

[0030] The preparation method is basically the same as in Example 1, except that in step 1), citric acid is used to adjust the pH of the system to 2.9, specifically: 1) Grind the copper source, vanadium source, and sulfur source separately in a mortar and pestle, and then add them to 60 ml of deionized water. The molar ratio of copper, vanadium, and sulfur is 3:1:12. After stirring evenly at room temperature, adjust the pH of the system to 2.9 with ammonia water to obtain a mixed solution. The copper source is copper chloride, the vanadium source is ammonium metavanadate, and the sulfur source is thiourea. 2) Transfer the mixed solution obtained in step 1) into a 100ml reaction vessel liner and load it into the reaction vessel; heat to 200℃ and react at the reaction temperature of 200℃ for 1 day. After the reaction is completed, cool to room temperature to obtain the reaction solution. 3) Take the cooled reaction solution and place it in a centrifuge tube. Centrifuge it three times with deionized water and ethanol alternately at a speed of 10,000 rpm for 8 minutes each time. Remove the supernatant. Then dry the centrifuged solid in a vacuum oven at 60°C for 12 hours to obtain vanadium-based sulfide Cu3VS4 for magnesium-ion batteries.

[0031] Comparative Example 2 The method for preparing copper sulfide for magnesium-ion batteries provided in this comparative example includes the following steps: 1) Grind the copper source and sulfur source separately in a mortar and pestle, and then add them to 60 ml of deionized water. The molar ratio of copper to sulfur is 1:1.5. Stir the mixture at room temperature to obtain a mixed solution. The copper source is copper nitrate and the sulfur source is thiourea. 2) Transfer the mixed solution obtained in step 1) into a 100ml reaction vessel liner and place it into the reaction vessel. Heat to 200℃ and react at 200℃ for 2 days. After the reaction is complete, cool to room temperature to obtain the reaction solution; 3) Take the cooled reaction solution and place it in a centrifuge tube. Centrifuge it three times with deionized water and ethanol alternately at a speed of 10,000 rpm for 8 minutes each time. Remove the supernatant. Then dry the centrifuged solid in a vacuum oven at 60°C for 12 hours to obtain copper sulfide for magnesium-ion batteries.

[0032] Performance characterization: This application uses Example 1 as an example to characterize the vanadium-based sulfide heterostructures prepared in Examples 1 and 3-4, and to perform performance tests on the vanadium-based sulfide heterostructures prepared in the examples, the copper thiovanadate prepared in Comparative Example 1, and the copper sulfide prepared in Comparative Example 2. Furthermore, a performance comparison study is conducted between Examples 1, 3-4, and Comparative Examples 1-2, specifically as follows: 1) Investigation of phases at different pH levels This test example uses XRD diffraction equipment to test the crystal structure of the copper thiovanadate heterostructures prepared in Examples 1 and 3-4. The XRD patterns of the copper thiovanadate heterostructures obtained at pH 11, 12, and 13 are as follows: Figure 1 , 2 As shown in Figures 3 and 1, the successful synthesis of the copper thiovanadate heterostructure is evident from the figures.

[0033] Table 1 shows the phase content results of the copper thiovanadate heterostructure cathode materials with pH control systems of 12, 11, and 13 provided in Examples 1 and 3-4 of this invention: Table 1. Phase content of copper thiovanadate heterostructure cathode materials at pH 12, 11, and 13 2) Microscopic morphology This test example uses scanning electron microscopy to examine the microstructure of the copper thiovanadate heterostructures prepared in Examples 1 and 3-4. The SEM images of the copper thiovanadate heterostructures obtained at pH 11, 12, and 13 are shown below. Figure 4 , 5 As shown in Figures 1 and 6, the copper thiovanadate heterostructures prepared in Examples 1 and 3-4 of this application are predominantly spherical in shape.

[0034] 3) Electrical properties Test methods: Full cells assembled with Mg as the negative electrode, copper thiovanadate heterostructure as the positive electrode, copper sulfide as the positive electrode, and MCT as the electrolyte were tested at a current density of 200 mA / g using the Xinwei charge-discharge equipment; Full cells assembled with Mg as the negative electrode, copper thiovanadate as the positive electrode, and MCT as the electrolyte were tested at a current density of 50 mA / g using the Xinwei charge-discharge equipment. Results and Discussion: The electrochemical performance of the copper thiovanadate heterostructures obtained at pH 11, 12, and 13 in this test at a current density of 2000 mA / g is shown in the figure below. Figure 7 As shown in the figure, the copper thiovanadate heterostructure prepared in Example 1 of this application has an electrical performance of 202 mAh / g after activation at 200 mA / g; the copper thiovanadate prepared in Comparative Example 1 has an electrical performance of 40 mAh / g after activation at 50 mA / g; and the copper sulfide prepared in Comparative Example 2 has an electrical performance of 78 mAh / g after activation at 200 mA / g. In summary, the vanadium-based sulfide heterostructure prepared in this application exhibits excellent electrical properties; compared with single-component copper thiovanadate, the electrical properties are significantly improved.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a vanadium-based sulfide heterostructure, characterized in that, Includes the following steps: 1) Grind the copper source, vanadium source and sulfur source separately in a mortar and pestle, add them to deionized water, stir evenly at room temperature, and adjust the pH of the system to 10-13 to obtain a mixed solution; 2) Transfer the mixed solution obtained in step 1) to deionized water, mix thoroughly, and then heat to react. After the reaction is complete, cool, centrifuge, and dry to obtain a vanadium-based sulfide heterostructure.

2. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The molar ratio of copper, vanadium and sulfur is 3:1:(6-20).

3. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The copper source is any one or a combination of at least two of the following: copper fluoride, copper chloride, copper bromide, copper nitrate, copper sulfate, copper carbonate, copper oxalate, copper acetate, basic copper carbonate, copper hydroxide, copper oxide, copper sulfide, and copper acetylacetonate.

4. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The vanadium source is any one or a combination of at least two of ammonium metavanadate, vanadium acetylacetonate, and sodium orthovanadate.

5. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The sulfur source is any one or a combination of at least two of thioacetamide, thiourea, and L-cysteine.

6. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The volume of the mixed solution mentioned in step 2) accounts for 1 / 2 to 3 / 4 of the total volume of the reaction system.

7. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The process conditions for the heating reaction in step 2) are: react at a temperature of 160-230℃ for 1-3 days.

8. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The centrifugation process conditions in step 2) are as follows: Take the cooled reaction solution and place it in a centrifuge tube. Centrifuge with deionized water and ethanol alternately 2-5 times at a centrifugation speed of 8000-12000 rpm for 2-10 min each time, and remove the supernatant.

9. The method for preparing vanadium-based sulfide heterostructures according to claim 1, characterized in that, The drying process conditions are as follows: drying in a vacuum oven at 50-70℃ for 10-15 hours.

10. The application of a vanadium-based sulfide heterostructure obtained by any one of claims 1-9 in a magnesium secondary battery.

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