Preparation Method and Application of a High-Entropy Catalyst Tungsten Molybdenum Tellurium Selenium Sulfide

Abstract

The present invention discloses a preparation method and application of a high-entropy catalyst tellurium-selenium-sulfur-tungsten-molybdenum, belonging to the technical field of energy materials. The preparation method includes: adding selenium powder into a hydrazine hydrate solution to form solution A; dissolving sodium molybdate dihydrate, tungsten chloride and thiourea in a reduced graphene oxide suspension to form a mixed solution B; mixing solution A and solution B together and stirring to obtain solution C, transferring solution C to an autoclave for hydrothermal reaction; washing the product obtained from the reaction with deionized water, and freeze-drying after washing to obtain a black product A; placing product A at the downwind of a tube furnace and tellurium powder at the upwind of the tube furnace, and performing annealing treatment in an argon-hydrogen gas environment to obtain a tellurium-selenium-sulfur-tungsten-molybdenum catalyst. By adopting the above preparation method and application of a high-entropy catalyst tellurium-selenium-sulfur-tungsten-molybdenum, the present invention is beneficial to the rapid transmission of electrons, improves the transmission efficiency of ions and electrons, and enhances the kinetic performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of energy materials, and particularly to a preparation method and application of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide. Background Art

[0002] The energy issue is one of the important challenges faced globally, including aspects such as energy supply security, climate change, and environmental pollution. In this context, lithium-ion batteries, as an efficient and rechargeable energy storage technology, have become an important tool for solving energy problems. With the growing global demand for sustainable energy, the improvement of their performance and materials has become the focus of scientific research. Among them, lithium-sulfur (Li-S) batteries have become a powerful alternative to traditional lithium-ion batteries due to their high theoretical energy density, low cost, and abundance of sulfur resources. The chemical reaction of Li-S batteries involves a reversible electrochemical reaction between lithium and sulfur, with the potential for higher energy storage capacity than traditional battery technologies. However, to fully realize the potential of Li-S batteries and commercialize them, several challenges need to be addressed, mainly including the shuttle effect of polysulfides, volume changes of electrode materials, and slow redox kinetics. Although traditional single-component or two-component catalysts can improve these problems to some extent, due to the inherent limitations of single materials, their effects are often unsatisfactory. In contrast, high-entropy catalysts, due to the rich active sites and highly disordered crystal structures brought about by their multi-element combinations, can promote electrochemical reactions under a wider range of conditions, demonstrating catalytic activity and stability beyond conventional materials. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method and application of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide. The diverse element combinations within the high-entropy catalyst form complex electron transfer paths, which are conducive to the rapid transmission of electrons, thereby improving the ion and electron transport efficiency and enhancing the kinetic performance of the battery.

[0004] To achieve the above purpose, the present invention provides a preparation method of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide, comprising the following steps:

[0005] S1. Add selenium powder to a hydrazine hydrate solution to form solution A;

[0006] S2. Dissolve sodium molybdate dihydrate, tungsten chloride, and thiourea in a reduced graphene oxide suspension to form a mixed solution B;

[0007] S3. Mix solution A and solution B together and stir to obtain solution C, and transfer solution C to an autoclave for hydrothermal reaction;

[0008] S4. Wash the product obtained from the reaction with deionized water, and freeze-dry after washing to obtain a black product A;

[0009] S5. Place product A at the downwind side of the tube furnace and tellurium powder at the upwind side of the tube furnace, and perform annealing treatment in an argon-hydrogen environment to obtain a tellurium-selenium-sulfurized tungsten-molybdenum catalyst.

[0010] Preferably, in S1, the mixing temperature of selenium powder and hydrazine hydrate solution is 50 - 100 °C, the purity of selenium powder > 99.99%, the particle size < 75 µm, and the purity of hydrazine hydrate is analytical pure.

[0011] Preferably, in S2, the purity of sodium molybdate dihydrate > 99%, the purity of tungsten chloride > 99%, the purity of thiourea > 99.9%, and the concentration of reduced graphene oxide in solution B is 3 - 20 mg / mL.

[0012] Preferably, in S3, the stirring time is 0.25 - 3 h, the stirring temperature is 40 - 80 °C, the temperature of the hydrothermal reaction is 160 - 250 °C, and the reaction time is 10 - 30 h.

[0013] Preferably, in S5, the mass ratio of tellurium powder to product A is 1:2 - 0.1, the annealing temperature is 400 - 800 °C, and the annealing time is 1 - 6 h.

[0014] Preferably, the concentrations of selenium powder, sodium molybdate dihydrate, tungsten chloride, and thiourea in solution C are all 2 - 8 mmol / mL.

[0015] Preferably, the volume percentage content of hydrazine hydrate in solution C is 10 - 50%.

[0016] Preferably, the mass percentage content of single elements of S, Se, Te, W, and Mo in the tellurium-selenium-sulfurized tungsten-molybdenum catalyst is 10 - 80%.

[0017] The present invention also provides an application of a high-entropy catalyst tellurium-selenium-sulfurized tungsten-molybdenum. The tellurium-selenium-sulfurized tungsten-molybdenum catalyst prepared by the preparation method of a high-entropy catalyst tellurium-selenium-sulfurized tungsten-molybdenum described above is used as a cathode material for preparing a lithium-sulfur battery.

[0018] Therefore, the present invention adopts the above preparation method and application of a high-entropy catalyst tellurium-selenium-sulfurized tungsten-molybdenum, and has the following beneficial effects:

[0019] (1) The present invention combines chalcogens Te, Se, and S with W and Mo simultaneously to form a high-entropy catalyst. This high-entropy catalyst surface is rich in various types of active sites, which can strongly adsorb and catalyze polysulfides, reducing the so-called shuttle effect, while promoting the conversion of polysulfides and accelerating the progress of its electrochemical redox reaction. Secondly, the presence of multiple metal elements leads to changes in the d-orbital energy levels, enhancing the adsorption strength and selectivity of the catalyst for polysulfides, and further optimizing its catalytic performance. In addition, the special structures formed on the surface of the high-entropy catalyst (such as edges, defects, grain boundaries, etc.) provide additional active sites, significantly accelerating the reaction rate. The diversified element combination forms complex electron transfer paths, which is conducive to the rapid transmission of electrons, thereby improving the ion and electron transport efficiency and enhancing the kinetic performance of the battery. The synthesized catalyst has important practical application value in lithium-sulfur batteries.

[0020] (2) The preparation method of the present invention obtains the high-entropy catalyst tungsten molybdenum tellurium selenium sulfide with a large number of defects on the surface through simple and mild solution treatment and hydrothermal reaction. The control of the defect concentration and the ratio of tellurium selenium sulfur tungsten molybdenum is realized. By adjusting conditions such as reaction time, temperature, and the dosage of tellurium selenium sulfur tungsten molybdenum sources, the control of the defect concentration and the ratio of tellurium selenium sulfur tungsten molybdenum can be achieved.

[0021] (3) After the tungsten molybdenum tellurium selenium sulfide catalyst of the present invention is prepared into a lithium-sulfur battery, it has higher adsorption and catalytic activities for different polysulfides, higher energy density, and longer cycle life compared with the lithium-sulfur battery prepared with a single catalyst. Under the condition of 0.2C, the initial capacity is 1159 mAh·g -1 , and the capacity retention rate after 200 cycles is about 81.3%, showing great potential in lithium-sulfur batteries.

[0022] (4) The preparation method of the tungsten molybdenum tellurium selenium sulfide catalyst of the present invention is simple and easy to operate, does not require complex instrument equipment, uses tellurium selenium sulfur and tungsten molybdenum sources as synthesis materials, and is inexpensive compared with catalyst materials containing precious metals, suitable for industrial production.

[0023] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0024] Figure 1 is a scanning electron microscope (SEM) image of the tungsten molybdenum tellurium selenium sulfide catalyst prepared in Example 1 of the preparation method and application of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide of the present invention;

[0025] Figure 2 is an elemental distribution map of the tungsten molybdenum tellurium selenium sulfide catalyst prepared in Example 1 of the preparation method and application of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide of the present invention under a scanning electron microscope;

[0026] Figure 3 The constant current charge-discharge curves at a current of 1C of the tellurium-selenium-tungsten-molybdenum sulfide catalyst prepared in Example 1 of the preparation method and application of a high-entropy catalyst tellurium-selenium-tungsten-molybdenum of the present invention and the batteries prepared using the cathode materials of Comparative Example 1 and Comparative Example 2. Detailed implementation manners

[0027] The technical solution of the present invention will be further described below with reference to the accompanying drawings and examples.

[0028] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0029] The present invention provides a high-entropy catalyst tellurium-selenium-tungsten-molybdenum, which has a lamellar nanosheet morphology, grows uniformly on reduced graphene oxide, and has abundant defects. The preparation method thereof includes the following steps:

[0030] S1. Add selenium powder to a hydrazine hydrate solution to form solution A. Among them, the mixing temperature of the selenium powder and the hydrazine hydrate solution is 50-100 °C, the purity of the selenium powder > 99.99%, the particle size < 75 µm, and the purity of the hydrazine hydrate is analytical pure.

[0031] S2. Dissolve sodium molybdate dihydrate (Na2MoO4·2H2O), tungsten chloride (WCl), and thiourea in a reduced graphene oxide suspension (rGO) to form a mixed solution B. The purity of sodium molybdate dihydrate > 99%, the purity of tungsten chloride > 99%, the purity of thiourea > 99.9%, and the concentration of the reduced graphene oxide in solution B is 3-20 mg / mL.

[0032] S3. Mix solution A and solution B together and stir at 40-80 °C for 0.25-3 h to obtain solution C. Transfer solution C to an autoclave for hydrothermal reaction. The temperature of the hydrothermal reaction is 160-250 °C, the reaction time is 10-30 h, the volume percentage content of hydrazine hydrate in solution C is 10-50%, and the concentrations of selenium powder, sodium molybdate dihydrate, tungsten chloride, and thiourea in solution C are all 2-8 mmol / mL.

[0033] S4. Wash the product obtained from the reaction with deionized water, and then freeze-dry to obtain a black product A;

[0034] S5. Place product A at the downwind side of the tubular furnace and tellurium powder at the upwind side of the tubular furnace. Anneal under an argon-hydrogen gas environment. The annealing temperature is 400 - 800 °C and the annealing time is 1 - 6 h to obtain a tellurium-selenium-sulfurized tungsten molybdenum catalyst. The mass ratio of tellurium powder to product A is 1:2 - 0.1. The ratios of S, Se, Te, W, and Mo in the tellurium-selenium-sulfurized tungsten molybdenum catalyst are adjustable, and the mass percentage content of a single element is 10 - 80%.

[0035] In the present invention, chalcogen elements Te, Se, and S are simultaneously combined with W and Mo to form a high-entropy compound catalyst, tellurium-selenium-sulfurized tungsten molybdenum. The surface of the high-entropy catalyst is rich in various types of active sites, which can strongly adsorb polysulfides (LiPSs), preventing their dissolution and shuttling in the electrolyte, thereby reducing the so-called "shuttling effect", which is one of the main reasons for the performance degradation of lithium-sulfur batteries.

[0036] Meanwhile, the high-entropy catalyst can promote the conversion of polysulfides to Li2S, accelerating the progress of its electrochemical redox reaction and improving the cycle efficiency and energy output of the battery. Secondly, the presence of multiple metal elements in the high-entropy material leads to the complexity of the electronic structure, especially the change in the d-orbital energy level, which can effectively regulate the electronic state of the catalyst. This regulation of the d-band center can enhance the adsorption strength and selectivity of the catalyst for polysulfides, thereby optimizing its catalytic performance.

[0037] In addition, the special structures formed on the surface of the high-entropy catalyst (such as edges, defects, grain boundaries, etc.) provide additional active sites, which are particularly important for catalyzing the redox reaction of polysulfides and can significantly accelerate the reaction rate. The diversified element combination inside the high-entropy catalyst forms a complex electron transfer path, which is conducive to the rapid transmission of electrons, thereby improving the ion and electron transmission efficiency and enhancing the kinetic performance of the battery.

[0038] Example 1

[0039] The present invention provides a preparation method of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide, comprising the following steps: First, at 70 °C, 0.75 mmol of selenium powder is added to 2.5 mL of hydrazine hydrate solution (98%) to form solution A. Then, 0.75 mmol of sodium molybdate dihydrate, 0.75 mmol of tungsten chloride, and 0.75 mmol of thiourea are dissolved in 10 mL of reduced graphene oxide suspension (10 mg / mL) to form a mixed solution B. Solution A and solution B are mixed together and stirred for 15 minutes to obtain solution C. Solution C is transferred to a Teflon autoclave and stored at a temperature of 200 °C for 24 hours. The product obtained from the reaction is washed with deionized water and freeze-dried to obtain a black product A. Finally, annealing treatment is carried out using a tube furnace. 3 mmol of tellurium powder is placed at the upwind side, and product A is placed at the downwind side. Annealing treatment is carried out in an argon-hydrogen environment at 550 °C for 2 hours to obtain the tellurium selenium tungsten molybdenum sulfide catalyst.

[0040] Figure 1 As shown in the scanning electron microscope (SEM) image of Example 1, the tellurium selenium tungsten molybdenum layered nanosheets prepared in Example 1 grow uniformly on reduced graphene oxide, with an average size of about 100 nm.

[0041] Figure 2 It is the scanning electron microscope element distribution map of Example 1. It shows the uniform distribution of S, Se, Te and W, Mo elements on the rGO nanosheets, confirming the successful introduction of S, Se, Te, W, Mo.

[0042] Example 2

[0043] The present invention provides a preparation method of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide, comprising the following steps: First, at 70 °C, 1.5 mmol of selenium powder is added to 2.5 mL of hydrazine hydrate solution (98%) to form solution A. Then, 0.75 mmol of sodium molybdate dihydrate, 1.5 mmol of tungsten chloride, and 0.75 mmol of thiourea are dissolved in 10 mL of reduced graphene oxide suspension (10 mg / mL) to form a mixed solution B. Solution A and solution B are mixed together and stirred for 15 minutes to obtain solution C. Solution C is transferred to a Teflon autoclave and stored at a temperature of 200 °C for 24 hours. The product obtained from the reaction is washed with deionized water and freeze-dried to obtain a black product A. Finally, annealing treatment is carried out using a tube furnace. 2 mmol of tellurium powder is placed at the upwind side, and product A is placed at the downwind side. Annealing treatment is carried out in an argon-hydrogen environment at 600 °C for 2 hours to obtain the tellurium selenium tungsten molybdenum sulfide catalyst.

[0044] Example 3

[0045] The present invention provides a method for preparing a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide, comprising the following steps: First, at 70 °C, 0.75 mmol of selenium powder is added to 2.5 mL of hydrazine hydrate solution (98%) to form solution A. Then, 0.75 mmol of sodium molybdate dihydrate, 1 mmol of tungsten chloride and 1.5 mmol of thiourea are dissolved in 10 mL of reduced graphene oxide suspension (10 mg / mL) to form a mixed solution B. Solution A and solution B are mixed together and stirred for 15 minutes to obtain solution C. Solution C is transferred to a Teflon autoclave and stored at a temperature of 200 °C for 24 hours. The product obtained from the reaction is washed with deionized water and freeze-dried to obtain a black product A. Finally, annealing treatment is carried out using a tube furnace. 5 mmol of tellurium powder is placed at the upwind side, and product A is placed at the downwind side. Annealing treatment is carried out in an argon-hydrogen atmosphere at 700 °C for 2 hours to obtain the tungsten molybdenum tellurium selenium sulfide catalyst.

[0046] Comparative Example 1

[0047] Compared with Example 1, without solution A, tungsten chloride is not added to solution B, and the product obtained by hydrothermal treatment is annealed at 550 °C using a tube furnace under the protection of argon, and the remaining steps are the same, thus obtaining a molybdenum disulfide catalyst.

[0048] Comparative Example 2

[0049] Compared with Example 1, without solution A, sodium molybdate dihydrate is not added to solution B, and the product obtained by hydrothermal treatment is annealed at 550 °C using a tube furnace under the protection of argon, and the remaining steps are the same, thus obtaining a tungsten disulfide catalyst.

[0050] To evaluate the effectiveness of the tungsten molybdenum tellurium selenium sulfide catalyst in actual lithium-sulfur batteries, sulfur is incorporated into the catalysts prepared in Comparative Example 1, Comparative Example 2 and Example 1 by a traditional melt impregnation method to form a sulfur cathode and prepare it into a battery. The experimental steps are as follows: The synthesized catalyst and sulfur are combined by grinding and then heated in an inert atmosphere at 155 °C for 12 hours. Subsequently, the active material (70%), polyvinylidene fluoride (PVDF, 10%) and carbon black (20%) are dissolved in N-methylpyrrolidone (NMP) to prepare a slurry. Then the slurry is coated on an aluminum foil and dried in a vacuum oven at 60 °C for 12 h. The dried coated foil is cut into thin slices with a diameter of 10 mm. The cathodes synthesized in Comparative Example 1, Comparative Example 2 and Example 1 are S@MoS2 / rGO, S@WS2 / rGO and S@WMoSSeTe / rGO respectively.

[0051] Figure 3Performance graphs of the batteries prepared from the composite materials of Comparative Example 1, Comparative Example 2 and Example 1. The batteries were subjected to a cycling test under 1C condition. The discharge capacity of the S@WMoSSeTe / rGO-based battery prepared in Example 1 was 1159 mAh·g -1 , exceeding that of the S@MoS2 / rGO-based battery (824 mAh·g -1 ) in Comparative Example 1 and the S@WS2 / rGO-based battery (997 mAh·g -1 ) in Comparative Example 2. This is because the special structures (such as edges, defects, grain boundaries, etc.) formed on the surface of the high-entropy catalyst provide additional active sites, significantly accelerating the reaction rate. The diversified element combination forms a complex electron transfer path, which is conducive to the rapid transmission of electrons, thereby improving the ion and electron transport efficiency and enhancing the kinetic performance of the battery.

[0052] Therefore, in the present invention, the preparation method and application of the above-mentioned high-entropy catalyst tungsten molybdenum tellurium selenide sulfide are adopted. The surface of the prepared high-entropy catalyst tungsten molybdenum tellurium selenide sulfide is rich in various types of active sites, which can strongly adsorb and catalyze polysulfides, reducing the so-called shuttle effect, while promoting the conversion of polysulfides and accelerating the progress of its electrochemical redox reaction; secondly, the presence of multiple metal elements leads to changes in the d-orbital energy levels, enhancing the adsorption strength and selectivity of the catalyst for polysulfides, and further optimizing its catalytic performance; in addition, the diversified element combination forms a complex electron transfer path, which is conducive to the rapid transmission of electrons, thereby improving the ion and electron transport efficiency and enhancing the kinetic performance of the battery.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a high-entropy catalyst tellurium selenium tungsten molybdenum sulfide, characterized in that: It includes the following steps: S1. Add selenium powder into hydrazine hydrate solution to form solution A; S2. Dissolve sodium molybdate dihydrate, tungsten chloride and thiourea in the reduced graphene oxide suspension to form mixed solution B; S3. Mix solution A and solution B together and stir to obtain solution C, and transfer solution C to an autoclave for hydrothermal reaction; S4. Wash the product obtained from the reaction with deionized water, and freeze-dry after washing to obtain black product A; S5. Place product A at the downwind of a tube furnace and tellurium powder at the upwind of the tube furnace, and perform annealing treatment in an argon-hydrogen gas environment to obtain a tellurium-selenium-tungsten-molybdenum sulfide catalyst.

2. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 1, characterized in that: In S1, the mixing temperature of selenium powder and hydrazine hydrate solution is 50 - 100 °C, the purity of selenium powder > 99.99%, the particle size < 75 μm, and the purity of hydrazine hydrate is analytical pure.

3. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 2, characterized in that: In S2, the purity of sodium molybdate dihydrate > 99%, the purity of tungsten chloride > 99%, the purity of thiourea > 99.9%, and the concentration of reduced graphene oxide in solution B is 3 - 20 mg / mL.

4. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 3, characterized in that: In S3, the stirring time is 0.25 - 3 h, the stirring temperature is 40 - 80 °C, the hydrothermal reaction temperature is 160 - 250 °C, and the reaction time is 10 - 30 h.

5. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 4, characterized in that: In S5, the mass ratio of tellurium powder to product A is 1:2 - 0.1, the annealing temperature is 400 - 800 °C, and the annealing time is 1 - 6 h.

6. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 5, characterized in that: The concentrations of selenium powder, sodium molybdate dihydrate, tungsten chloride and thiourea in solution C are all 2 - 8 mmol / mL.

7. The preparation method of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide according to claim 6, characterized in that: The volume percentage content of hydrazine hydrate in solution C is 10 - 50%.

8. Application of a high-entropy catalyst tungsten molybdenum tellurium selenium sulfide, characterized in that: Use the tellurium-selenium-tungsten-molybdenum sulfide catalyst prepared by the preparation method of a high-entropy catalyst tellurium-selenium-tungsten-molybdenum described in claim 7 as a cathode material for preparing a lithium-sulfur battery.

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