Transition metal sulfide as well as preparation method and application thereof

Abstract

The invention discloses transition metal sulfide as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) dissolving a molybdenum source in deionized water to obtain a solution A; (2) dissolving other metal sources in deionized water to obtain a solution B; (3) adding the solution B into the solution A, reacting, filtering, washing and drying to obtain a polyoxometallate precursor; (4) adding the polyoxometallate precursor and a sulfur source into a sealed high-temperature-resistant container, uniformly mixing, sealing in vacuum, normal pressure or pressurization, and calcining; and (5) washing and drying to obtain the transition metal sulfide. The method better inherits the morphology advantage of the precursor, the reaction time is short, the technological process is simple and safe, the use of a high-pressure closed environment and a toxic solvent is avoided, the operation risk is low, the energy consumption is low, and the problems that the emission of harmful gas is large and the utilization rate of a sulfur source is low in the vulcanization process are effectively solved; the transition metal sulfide in the sodium ion battery is good in battery rate capability and high in long-cycle constant-current charge-discharge performance stability.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery anode material synthesis technology, specifically relating to a transition metal sulfide, its preparation method, and its uses. Background Technology

[0002] Sodium-ion batteries have attracted widespread attention in large-scale energy storage and electric vehicle fields due to their abundant resources and low cost. Among the many sodium-ion battery anode materials, transition metal sulfides exhibit excellent sodium-ion storage performance due to their diverse composition, tunable crystal structure, high redox activity, and controllable nanostructure, such as high theoretical specific capacity and good rate performance, and are considered a promising class of sodium-ion battery anode materials. Currently, the synthesis methods of transition metal sulfides mainly rely on solvothermal methods and high-temperature calcination sulfidation methods, such as: Literature (Peng et al., Adv. Sci. (2025, e2417288.) Using Cu(NO3)2·3H2O and Na2MoO4·2H2O as metal sources and polyvinylpyrrolidone surfactant, transition metal precursors were prepared. Transition metal sulfides CuS@MoS2 were then successfully prepared via a thiourea hydrothermal sulfidation method (reaction temperature 200 ℃, reaction time 24 h). This method has advantages such as simple operation, low reaction temperature, high production safety, simple waste treatment, and excellent product performance. When used as the anode of a sodium-ion battery, the transition metal sulfide exhibited a long-cycle constant current charge-discharge capacity of 506.03 mAh / g at a current density of 5.0 A / g, and a rate capability of 500.96 mAh / g at a current density of 7.0 A / g.

[0003] Patent publication number CN 117512558 A discloses a class of two-dimensional transition metal / alloy sulfides and their preparation method. This patent uses transition metal oxoacid salts as precursors and sulfur-containing elemental salts as the sulfur source, preparing two-dimensional transition metal / alloy sulfides through a high-temperature calcination sulfidation method (760 ℃, 860 ℃, or 950 ℃). This method features highly controllable product layer number, high product quality, economy, and strong universality.

[0004] However, the existing synthesis methods still have many bottlenecks in material controllability, process greenness and large-scale production, etc. For example, the solvothermal method has the problems of raw material loss and morphology failure caused by precursor dissolution, the need to add surfactants to maintain the effectiveness of the precursor, long reaction period, the use of toxic organic solvents, poor process repeatability, and easy to cause product phase separation, which is not conducive to mass production and large-scale application. On the other hand, the high-temperature calcination sulfuration method generally has the problems of large operation safety hidden danger, large sulfur source loss, high harmful waste gas emission, complex process flow, low yield, high equipment investment and high energy consumption, etc. These bottlenecks in the preparation process not only increase the production cost, but also limit the uniformity and stability of the material.

[0005] Therefore, it is an urgent need to develop a transition metal sulfide and a preparation method thereof with simple process flow, mild conditions, green environmental protection, safe operation, low equipment investment, easy to scale production, and precise control of components and structure to obtain a transition metal sulfide with high stability and excellent electrochemical performance, which promotes the development and industrial application of sodium ion battery technology. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a transition metal sulfide.

[0007] The second purpose of the present application is to provide a preparation method of a transition metal sulfide.

[0008] The third purpose of the present application is to provide a use of a transition metal sulfide in a sodium ion battery.

[0009] The technical scheme of the present application is summarized as follows: A preparation method of a transition metal sulfide, comprising the following steps: (1) dissolving a molybdenum source in deionized water to obtain a solution A; (2) dissolving other metal sources in deionized water to obtain a solution B; (3) adding the solution B to the solution A, reacting, filtering, washing the solid with deionized water, and drying to obtain a polyoxometalate precursor; (4) adding the polyoxometalate precursor and a sulfur source into a sealed high-temperature resistant container, mixing uniformly, and calcining under vacuum, normal pressure or pressurized sealing; (5) washing the product obtained in step (4) with anhydrous ethanol and n-hexane in sequence, and drying at room temperature to obtain a transition metal sulfide.

[0010] Preferably, the molar ratio of the molybdenum source and the other metal sources is (1-6) : 1.

[0011] Preferably, the molybdenum source in step (1) is ammonium heptamolybdate tetrahydrate, ammonium molybdate, sodium molybdate dihydrate or potassium molybdate.

[0012] Preferably, the other metal source in step (2) is composed of metal cations and anions, the metal cations are copper, iron, cobalt, nickel, manganese, zinc or chromium; the anions are at least one of chloride, nitrate, sulfate and acetate.

[0013] Preferably, the temperature of the reaction in step (3) is 80-100 ℃, and the reaction time is 2-30 minutes.

[0014] Preferably, the mass ratio of the polyoxometalate precursor and the sulfur source in step (4) is 1:(1.5-5).

[0015] Preferably, the sulfur source is at least one of sulfur, sodium sulfide nine hydrates, thiourea, hydrogen sulfide, thioacetamide, sodium sulfite, sodium bisulfite and sodium thiosulfate five hydrates.

[0016] Preferably, the temperature of the calcination is 300-500 ℃, and the calcination time is 2-4 h.

[0017] A transition metal sulfide prepared by the above preparation method.

[0018] Use of the above transition metal sulfide in a sodium ion battery Beneficial effects The transition metal sulfide of the present application presents a three-dimensional flower-like structure of 6-8 μm, which can expose more electrochemically active sites, and is beneficial to the rapid migration and interfacial reaction of sodium ions. At the same time, the elements in the material are highly uniformly distributed, effectively avoiding the local phase separation problem caused by the difference in reaction kinetics in traditional methods such as solvothermal method, thereby ensuring the structural consistency and electrochemical stability of the material.

[0019] In terms of synthesis method, the present application has significant green and economic advantages. The entire preparation process does not use any expensive, toxic or difficult to remove organic solvents, surfactants or structural additives, only uses inexpensive metal salts and sulfur sources, and quickly obtains polyoxometalate precursors with flexible component adjustment through simple water phase heating and stirring. The subsequent sulfuration process has mild conditions, short time and high efficiency, and the excess sulfur source can be recycled and reused, which reduces waste gas emission and raw material waste from the source.

[0020] Compared with the traditional solvothermal method, the precursor morphology advantage can be better inherited, the reaction time is significantly shortened, the process flow is simpler and safer, the use of high-pressure closed environment and toxic solvents is avoided, and better mass production feasibility is achieved; compared with the high-temperature tube furnace calcination sulfuration method, the method does not require complex equipment, the operation risk is low, the energy consumption is significantly reduced, and the problems of large harmful gas emission and low sulfur source utilization rate in the sulfuration process are effectively solved; the overall process route is simple, environmentally friendly, easy to post-treat, low in equipment investment, and short in production cycle, and is suitable for large-scale preparation of high-performance transition metal sulfides. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Field emission scanning electron microscope image of the polyoxometalate precursor prepared in Example 1.

[0022] Figure 2 Field emission scanning electron microscope image of a transition metal sulfide (referred to as CuMo-S) prepared in Example 1.

[0023] Figure 3 Elemental distribution map of CuMo-S prepared in Example 1.

[0024] Figure 4 Field emission scanning electron microscope image of F-MoS2 prepared in Comparative Example 1.

[0025] Figure 5 Field emission scanning electron microscope image of F-CuS prepared in Comparative Example 2.

[0026] Figure 6 X-ray diffraction pattern of the samples prepared in Example 1 and Comparative Examples 1-2.

[0027] Figure 7 Battery rate performance comparison chart of the samples prepared in Example 1 and Comparative Examples 1-2.

[0028] Figure 8 Battery long cycle constant current charge-discharge performance comparison chart of the samples prepared in Example 1 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0029] The application will be further described below through specific examples.

[0030] Seal the high-temperature resistant container, preferably a quartz reactor or a stainless steel high-pressure reaction kettle, or other sealed high-temperature resistant containers can also be selected.

[0031] Example 1 A preparation method of a transition metal sulfide, comprising the following steps: (1) Put (NH4)6Mo7O24 • 4H2O (4.2 mmol) was dissolved in 80 mL of deionized water to obtain solution A; (2) Cu(NO3)2-3H2O (4.2 mmol) was dissolved in 20 mL of deionized water to obtain solution B; (3) Solution B was added to solution A, and reacted at 90 °C for 15 minutes. The solid was washed with deionized water three times and dried to obtain a polyoxometalate precursor; (4) The polyoxometalate precursor (1 g) and a sulfur source (sulfur, 1.5 g) were added to a sealed high-temperature-resistant container (a quartz reactor), mixed uniformly, and vacuum sealed (0 MPa). Calcination was performed at 450 °C for 3 h; (5) The product obtained in step (4) was separated and recovered from the excess sulfur, washed with anhydrous ethanol three times, washed with n-hexane three times, and dried at room temperature to obtain a transition metal sulfide (CuMo-S).

[0032] The polyoxometalate precursor ( Figure 1 ) exhibited a red blood cell-like structure, and the transition metal sulfide CuMo-S exhibited a flower-like structure with a diameter of 6-8 μm ( Figure 2 ). Cu, Mo, and S elements were uniformly distributed in the sample (see Figure 3 ).

[0033] Example 2 A method for preparing a transition metal sulfide, comprising the following steps: (1) Na2MoO4-2H2O (4.2 mmol) was dissolved in 80 mL of deionized water to obtain solution A; (2) CrCl3-6H2O (2.1 mmol) was dissolved in 20 mL of deionized water to obtain solution B; (3) Solution B was added to solution A, and reacted at 100 °C for 2 minutes. The solid was washed with deionized water three times and dried to obtain a polyoxometalate precursor; (4) The polyoxometalate precursor (1 g) and a sulfur source (thioacetamide, 3 g) were added to a sealed high-temperature-resistant container (a quartz reactor), mixed uniformly, and sealed at normal pressure. Calcination was performed at 500 °C for 2 h; (5) The product obtained in step (4) was washed with anhydrous ethanol three times, washed with n-hexane three times, and dried at room temperature to obtain a transition metal sulfide (CrMo-S).

[0034] Example 3 A method for preparing a transition metal sulfide, comprising the following steps: (1) Dissolve (NH4)2MoO4(4.2 mmol) in 80 mL of deionized water to obtain solution A; (2) Dissolve NiSO4·6H2O (1.2 mmol) in 20 mL of deionized water to obtain solution B; (3) Add solution B to solution A and react at 90 ℃ for 20 minutes, filter, wash the solid with deionized water three times, and dry to obtain a polyoxometalate precursor; (4) Add the polyoxometalate precursor (1 g) and a sulfur source (sodium sulfide nine hydrate, 2.5 g; sodium thiosulfate five hydrate, 2.5 g) to a sealed high-temperature-resistant container (stainless steel high-pressure reaction kettle), mix uniformly, and vacuum seal (0 MPa); calcine at 500 ℃ for 3 h; (5) Wash the product obtained in step (4) with anhydrous ethanol three times, then wash with n-hexane three times, and dry at room temperature to obtain a transition metal sulfide (NiMo-S).

[0035] Experiments prove that a transition metal sulfide is obtained by respectively replacing NiSO4·6H2O in this embodiment with Fe(NO3)3·9H2O, Mn(CH3COO)2·4H2O, and ZnSO4·7H2O, and the other steps are the same as in this embodiment. Example 4 A method for preparing a transition metal sulfide includes the following steps: (1) Dissolve K2MoO4(4.2 mmol) in 80 mL of deionized water to obtain solution A; (2) Dissolve Co(CH3COO)2·4H2O (0.3 mmol) and CoCl2·6H2O (0.4 mmol) in 20 mL of deionized water to obtain solution B; (3) Add solution B to solution A and react at 80 ℃ for 30 minutes, filter, wash the solid with deionized water three times, and dry to obtain a polyoxometalate precursor; (4) Add the polyoxometalate precursor (1 g) and a sulfur source (thiourea, 3 g) to a sealed high-temperature-resistant container (stainless steel high-pressure reaction kettle), mix uniformly, and pressure seal (0.2 MPa); calcine at 300 ℃ for 4 h; (5) After separating and recovering excess sulfur from the product obtained in step (4), wash with anhydrous ethanol three times, then wash with n-hexane three times, and dry at room temperature to obtain a transition metal sulfide (CoMo-S).

[0036] Experiments prove that a transition metal sulfide is obtained by respectively replacing the sulfur source (thiourea) in this embodiment with hydrogen sulfide, sodium sulfite, or sodium bisulfite, and the other steps are the same as in this embodiment.

[0037] Comparative Example 1 (NH4)6Mo7O 24 ·4H2O (1 mmol) and thiourea (30 mmol) were dissolved in 30 mL of deionized water, stirred for 30 minutes, transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, and placed in a muffle furnace. Then, the temperature was raised to 180 °C at a rate of 5 °C / min and maintained for 24 h. The autoclave was naturally cooled to room temperature, and the black sample was washed with deionized water and anhydrous ethanol. Finally, the precipitate was dispersed in water by ultrasonic, freeze-dried to obtain F-MoS2.

[0038] The morphology of F-MoS2 powder is shown in Figure 4 (field emission scanning electron microscope image), and F-MoS2 is a nanoflower structure composed of nanosheets with a diameter of about 400 nm.

[0039] Comparative Example 2 Cu(NO3)2·3H2O (1 mmol) was used to replace (NH4)6Mo7O 24 ·4H2O (1 mmol) in Comparative Example 1, and the other steps were the same as in Comparative Example 1. The obtained product was called F-CuS.

[0040] The morphology of F-CuS powder is shown in Figure 5 (field emission scanning electron microscope image), and F-CuS is a nanoflower structure composed of nanosheets with a diameter of 6-8 μm.

[0041] From Figure 6 (X-ray diffraction pattern of the sample), it can be seen that the samples prepared in Example 1 and Comparative Examples 1-2 have a high degree of matching with the standard cards in the Inorganic Crystal Structure Database, indicating that the materials are successfully synthesized.

[0042] The CuMo-S, F-MoS2, and F-CuS prepared in Example 1 and Comparative Examples 1-2 were used as anode materials for sodium ion batteries. Figure 7 is a comparison chart of the rate performance of the batteries of the samples prepared in Example 1 and Comparative Examples 1-2. It can be seen that the rate performance of CuMo-S is more excellent, and can withstand a current density change of 0.5-20 A / g. Figure 8 is a comparison chart of the long cycle constant current charge-discharge performance of the batteries of the samples prepared in Example 1 and Comparative Examples 1-2. It can be seen from the chart that CuMo-S still maintains a capacity of 575.9 mAh / g after 2000 cycles at 5.0 A / g, which is significantly better than the comparative examples.

[0043] Experiments prove that the transition metal sulfide obtained in examples 2, 3 and 4 presents a flower-like structure similar to the flower-like structure of CuMo-S of example 1.

[0044] Experiments prove that the transition metal sulfide obtained in examples 2, 3 and 4 as an anode material for a sodium ion battery has similar rate performance and long cycle constant current charge and discharge performance to the transition metal sulfide obtained in example 1 as an anode material for a sodium ion battery.

[0045] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for the preparation of transition metal sulfides, characterized in that The method comprises the following steps: (1) dissolving a molybdenum source in deionized water to obtain solution A; (2) dissolving other metal sources in deionized water to obtain solution B; (3) adding solution B to solution A, reacting, filtering, washing the solid with deionized water, drying to obtain a polyoxometalate precursor; (4) adding the polyoxometalate precursor and a sulfur source into a sealed high-temperature-resistant container, mixing uniformly, vacuumizing, sealing at normal pressure or pressurizing, and calcining; (5) washing the product obtained in step (4) with anhydrous ethanol and n-hexane in sequence, drying at room temperature to obtain a transition metal sulfide.

2. The method of claim 1, wherein The molar ratio of the molybdenum source to the other metal sources is 1-6:

1.

3. The production method according to claim 1 or 2, characterized by The molybdenum source in step (1) is ammonium heptamolybdate tetrahydrate, ammonium molybdate, sodium molybdate dihydrate or potassium molybdate.

4. The production method according to claim 1 or 2, characterized by The other metal source in step (2) is composed of a metal cation and an anion, the metal cation is copper, iron, cobalt, nickel, manganese, zinc or chromium, and the anion is at least one of chloride, nitrate, sulfate and acetate.

5. The method of claim 1, wherein The reaction temperature in step (3) is 80-100 ℃, and the reaction time is 2-30 minutes.

6. The method of claim 1, wherein The mass ratio of the polyoxometalate precursor to the sulfur source in step (4) is 1:1.5-5.

7. The production method according to claim 1 or 6, characterized by The sulfur source is at least one of sulfur, sodium sulfide nonahydrate, thiourea, hydrogen sulfide, thioacetamide, sodium sulfite, sodium bisulfite and sodium thiosulfate pentahydrate.

8. The method of claim 1, wherein The calcination temperature is 300-500 ℃, and the calcination time is 2-4 h.

9. A transition metal sulfide prepared by the method of any one of claims 1-8.

10. Use of the transition metal sulfide of claim 9 in a sodium ion battery.

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