A method for preparing antimony sulfide with good crystallinity and its application in sodium-ion batteries

Abstract

This invention belongs to the field of nanomaterials technology, specifically, it is a method for preparing highly crystalline antimony sulfide and its application in sodium-ion batteries. This invention uses antimony oxide as the antimony source, dissolves the antimony source using sulfide salts, and obtains antimony sulfide precipitate by adjusting the pH of the solution. The specific steps include: S1, mixing the sulfide salt and antimony oxide, dissolving them in water by high-speed stirring, and adding a dispersant to obtain an antimony solution; S2, controlling the temperature of the antimony solution, adding an acid solution, adjusting the pH, and stirring the reaction to obtain a precipitate; S3, filtering the precipitate obtained in S2, washing it three times with anhydrous ethanol, and then drying it at low temperature to obtain antimony sulfide particles; calcining the antimony sulfide particles under inert gas protection to obtain highly crystalline nano-antimony sulfide. The advantages of this invention are that the prepared nano-antimony sulfide has uniform particle size, good dispersibility, and controllable morphology; the product has few impurities, high yield, and high output; the process is simple and low-cost.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a method for preparing antimony sulfide with good crystallinity and its application in sodium-ion batteries. Background Technology

[0002] Sb₂S₃ is a typical transition metal sulfide, belonging to the orthorhombic semiconductor system, and is an important semiconductor material with a wide range of applications. Patents CN107089681A and CN116903035A disclose the preparation of antimony sulfide for photocatalysts; patents CN109504939B and CN116497315A disclose the preparation of antimony sulfide thin films for use in solar cells.

[0003] In recent years, due to the depletion of fossil fuels and the complex diversity of the ecological environment, the development of sustainable and low-cost clean energy has become a hot research topic. Sodium-ion batteries (SIBs) have attracted great attention as an ideal alternative to sustainable energy systems due to their low cost and high performance.

[0004] Sodium-ion batteries, as novel rechargeable batteries with significant research value and application prospects, face a bottleneck in their commercialization due to the limitations imposed by anode materials. Antimony-based sulfur compounds, based on a dual sodium storage mechanism of reversible oxidation and alloying, possess extremely high theoretical specific capacity and are highly promising anode materials for sodium-ion batteries. However, during charge and discharge processes, severe volume expansion and low conductivity lead to poor cycle stability and rate performance, significantly hindering their development and application. Constructing nanoscale antimony-based sulfides with nanostructures is an effective strategy to address these shortcomings. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing antimony sulfide with good crystallinity and its application in sodium-ion batteries. Antimony oxide is used as a raw material and is dissolved in a sulfide salt solution to obtain an antimony solution. Then, the pH of the antimony solution is adjusted with an acid solution at low temperature. Under the dispersing and structure-guiding effects of a dispersant, antimony sulfide precipitates out. The obtained antimony sulfide is a crystallized, ordered nanostructure. The antimony sulfide precipitate is then calcined under low temperature and high pressure to obtain nano-antimony sulfide with good crystallinity.

[0006] To solve the above technical problems, the present invention adopts the following technical solution:

[0007] One objective of this invention is to provide a method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0008] S1, sulfur salt dissolution

[0009] The sulfide salt and antimony oxide are mixed evenly in a certain proportion and placed in a dissolving tank. Pure water is then added and stirred at high speed to ensure complete dissolution. After adjusting the antimony concentration, a dispersant is added and the mixture is stirred evenly to obtain an antimony solution.

[0010] S2, Adjusting acidity

[0011] Control the temperature of the antimony solution to 0–30°C, slowly add the acid solution while stirring, control the final pH, and continue stirring for 1–6 hours to obtain a precipitate.

[0012] S3, Filtration and Calcination

[0013] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol and then dried at low temperature to obtain antimony sulfide particles. The antimony sulfide particles were calcined under inert gas protection to obtain nano-antimony sulfide with good crystallinity.

[0014] Preferably, the sulfide salt in S1 is one of sodium sulfide, potassium sulfide or ammonium sulfide, and the mass ratio of the sulfide salt to antimony oxide is 2 to 8:1.

[0015] Sulfide salts serve as both solvents and precipitants for antimony oxide. If there is too little sulfide salt, the antimony oxide dissolves slowly, and the antimony precipitation is incomplete. If there is too much sulfide salt, hydrogen sulfide is easily generated and volatilized during the acid-regulated precipitation process, causing environmental pollution and waste of sulfide salts. Therefore, the preferred mass ratio of sulfide salts to antimony oxides is 2 to 8:1, and more preferably 3 to 6:1.

[0016] Preferably, the antimony concentration in S1 is 50-300 g / L; too low an antimony concentration will reduce production efficiency and increase wastewater volume, while too high a concentration will easily cause the precipitated powder to grow coarse, which is not conducive to powder refinement. More preferably, the antimony concentration is 100-250 g / L.

[0017] Preferably, the high-speed stirring rate in S1 is 1200-1500 rpm, and the stirring time is 20-30 min.

[0018] Preferably, the dispersant in S1 is one or more of ethylene glycol, PVP, and CTAB, and the amount added is 1 to 10% of the antimony solution mass.

[0019] Preferably, the acid in the acid solution in S2 is one or more of hydrochloric acid, acetic acid, oxalic acid, and citric acid.

[0020] Preferably, the mass fraction of the acid solution in S2 is 20-70%, and the addition rate is 2-10 ml / min. The addition rate directly affects the amount of acid added, and indirectly affects the precipitation reaction rate. Too low a rate will lead to a decrease in precipitation efficiency, while too high a rate will cause the particles to grow faster and become coarser. Therefore, the addition rate is preferably 2-10 ml / min, and more preferably 4-8 ml / min.

[0021] Preferably, the endpoint pH in S2 is 1 to 9, more preferably 2 to 7.

[0022] Preferably, the stirring rate in S2 is 400–1200 rpm, and the stirring reaction time is 1–6 h.

[0023] The temperature of the antimony solution affects the growth of the formed grains. If the temperature is too high, the grain growth rate will be too fast. Therefore, the temperature of the antimony solution is preferably 0-30℃, more preferably 0-20℃. Stirring is beneficial to the homogenization of the solution and the refinement of the particles. It is important to control the stirring rate and the stirring reaction time. If the stirring reaction time is too short, the reaction will be incomplete and the precipitation rate will be reduced. If the stirring reaction time is too long, the formed particles will be coarser. Therefore, the stirring rate is controlled at 400-1200 rpm and the stirring reaction time is controlled at 1-6 h. More preferably, the stirring rate is 600-1000 rpm and the stirring reaction time is 2-4 h.

[0024] Preferably, the calcination pressure in S3 is 0.5 to 2 MPa, more preferably 0.8 to 1.5 MPa.

[0025] Preferably, the calcination temperature in S3 is 150–400°C and the calcination time is 1–5 h. If the calcination temperature is too low, the crystal form transformation will be incomplete, and if the calcination temperature is too high, the powder will easily sinter and coarse. The calcination time affects the powder crystal form transformation rate. Therefore, the calcination temperature is 150–400°C and the calcination time is 1–5 h. More preferably, the calcination temperature is 200–350°C and the calcination time is 2–4 h.

[0026] Preferably, the low-temperature drying in S3 is performed at a temperature of 40–60°C for 18–24 hours.

[0027] Preferably, the inert gas is either nitrogen or argon.

[0028] The dissolution of sulfide salts and the adjustment of acidity are for the synthesis of antimony sulfide precipitate. This step is mainly to obtain antimony sulfide particles with uniform size and finer particle size. The purpose of calcination is to improve the grain size of the particles.

[0029] The reaction equations for S1-S3 are shown below:

[0030] The dissolution reaction of sulfide salts: Sulfide salts react with antimony oxide to form thioantimonates.

[0031] Sb₂O₃ + 6S 2- +3H₂O=2SbS₃ 3- +6OH -

[0032] Neutralization and precipitation reaction to adjust acidity: Thioantimonates react with acids to form amorphous antimony sulfide.

[0033] 2SbS3 3- +6H + =Sb2S3↓+3H2S↑

[0034] H + +OH - =H2O

[0035] H2S + OH - =HS - +H2O

[0036] (3) Calcination reaction of filtration and calcination: amorphous antimony sulfide is converted into crystalline antimony sulfide.

[0037] Sb₂S₃ (amorphous) = Sb₂S₃ (crystalline)

[0038] The second objective of this invention is to provide an application of highly crystalline antimony sulfide in sodium-ion batteries, wherein the application is as follows: nano-antimony sulfide prepared using S1-S3 can be used as a negative electrode active material in sodium-ion batteries.

[0039] By adopting the above technical solution, the technical effect achieved by this invention is as follows:

[0040] 1. Antimony oxide is readily soluble in sulfide salts and has high solubility, making antimony sulfide production easier to control and more efficient. The yield of nano-antimony sulfide is even higher, exceeding 95%.

[0041] 2. Antimony sulfide precipitates at low temperatures, reducing the grain growth rate and resulting in finer and more uniform antimony sulfide particles.

[0042] 3. The crystal transformation of antimony sulfide is achieved through calcination. Under high pressure, the crystal transformation is faster, and the transformation temperature is reduced, thus reducing energy consumption.

[0043] 4. Adding a dispersant to the antimony solution can disperse and guide the antimony sulfide to grow along the crystal plane, resulting in better dispersibility. Attached Figure Description

[0044] Figure 1 This is a flowchart of S1-S3 of the present invention;

[0045] Figure 2 The XRD results are for uncalcined antimony sulfide particles in Examples 1, 2, and 3 of this invention.

[0046] Figure 3 The XRD results of nano-antimony sulfide after calcination in Examples 1 and 3 of this invention are shown.

[0047] Figure 4 , 5 This is a SEM image of nano-antimony sulfide in Example 2 of the present invention;

[0048] Figure 6 The number of cycles for sodium-ion battery anode active materials made from nano-antimony sulfide in Examples 1-3. Detailed Implementation

[0049] The present invention will be further illustrated below with reference to specific embodiments.

[0050] Example 1: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0051] S1, sulfur salt dissolution

[0052] Mix 40g of sodium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 50g / L and then add ethylene glycol dispersant. Mix evenly to obtain an antimony solution.

[0053] The high-speed stirring rate is 1300 rpm, and the stirring time is 25 min.

[0054] The amount of ethylene glycol dispersant added accounts for 7% of the mass of the antimony solution.

[0055] S2, Adjusting acidity

[0056] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 10℃. The stirring speed was adjusted to 1000 rpm. While stirring, a peristaltic pump was turned on to slowly add a 40% hydrochloric acid solution at a rate of 6 ml / min. The final pH was controlled to be 1. The reaction was continued for 2 hours to obtain a precipitate.

[0057] S3, Filtration and Calcination

[0058] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at low temperature (50°C) for 20 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under nitrogen protection, the high-purity nitrogen gas inside the tube was completely purged to maintain a pressure of 2 MPa. The furnace was then calcined at 150°C for 2 hours to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.33 g and a yield of 97.34%.

[0059] Example 2: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0060] S1, sulfur salt dissolution

[0061] Mix 60g of sodium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 150g / L and then add PVP dispersant. Mix evenly to obtain an antimony solution.

[0062] The high-speed stirring rate is 1200 rpm, and the stirring time is 30 min.

[0063] The amount of PVP dispersant added is 3% of the mass of the antimony solution.

[0064] S2, Adjusting acidity

[0065] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 20℃. The stirring speed was adjusted to 600 rpm. While stirring, a peristaltic pump was turned on to slowly add a 20% hydrochloric acid solution at a rate of 10 ml / min. The final pH was controlled at 5. The reaction was continued for 4 hours to obtain a precipitate.

[0066] S3, Filtration and Calcination

[0067] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at a low temperature of 40°C for 24 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under nitrogen protection, the high-purity nitrogen gas inside the tube was completely purged to maintain a pressure of 1 MPa. The furnace was then calcined at 250°C for 1 hour to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.41 g and a yield of 98.02%.

[0068] Example 3: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0069] S1, sulfur salt dissolution

[0070] Mix 60g of potassium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 200g / L and then add PVP dispersant. Mix evenly to obtain an antimony solution.

[0071] The high-speed stirring rate is 1500 rpm, and the stirring time is 20 min.

[0072] The amount of PVP dispersant added is 5% of the mass of the antimony solution.

[0073] S2, Adjusting acidity

[0074] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 5℃. The stirring speed was adjusted to 800 rpm. While stirring, a peristaltic pump was turned on to slowly add a 40% oxalic acid solution at a rate of 2 ml / min. The final pH was controlled at 9. The reaction was continued for 6 hours to obtain a precipitate.

[0075] S3, Filtration and Calcination

[0076] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at a low temperature of 60°C for 18 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under nitrogen protection, the high-purity nitrogen gas inside the tube was completely purged to maintain a pressure of 1.5 MPa. The furnace was then calcined at 350°C for 4 hours to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.39 g and a yield of 97.85%.

[0077] Example 4: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0078] S1, sulfur salt dissolution

[0079] Mix 20g of potassium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 100g / L and then add CTAB dispersant. Mix evenly to obtain an antimony solution.

[0080] The high-speed stirring rate is 1400 rpm, and the stirring time is 30 min.

[0081] The amount of CTAB dispersant added is 9% of the mass of the antimony solution.

[0082] S2, Adjusting acidity

[0083] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 15℃. The stirring speed was adjusted to 1200 rpm. While stirring, a peristaltic pump was turned on to slowly add a 70% citric acid solution at a rate of 8 ml / min. The final pH was controlled at 7. The reaction was continued for 3 hours to obtain a precipitate.

[0084] S3, Filtration and Calcination

[0085] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at low temperature (50°C) for 22 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under argon protection, the high-purity argon gas inside the tube was completely purged to maintain a pressure of 0.5 MPa. The furnace was then calcined at 300°C for 3 hours to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.17 g and a yield of 95.96%.

[0086] Example 5: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0087] S1, sulfur salt dissolution

[0088] Mix 80g of ammonium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 300g / L and then add CTAB dispersant. Mix evenly to obtain an antimony solution.

[0089] The high-speed stirring rate is 1500 rpm, and the stirring time is 20 min.

[0090] The amount of CTAB dispersant added is 10% of the mass of the antimony solution.

[0091] S2, Adjusting acidity

[0092] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 0℃. The stirring speed was adjusted to 400 rpm, and while stirring, a peristaltic pump was turned on to slowly add a 60% acetic acid solution at a rate of 4 ml / min. The final pH was controlled at 3, and the reaction was continued for 1 hour to obtain a precipitate.

[0093] S3, Filtration and Calcination

[0094] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at a low temperature of 60°C for 18 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under argon protection, the high-purity argon gas inside the tube was completely purged to maintain a pressure of 1 MPa. The furnace was then calcined at 200°C for 5 hours to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.46 g and a yield of 98.45%.

[0095] Example 6: A method for preparing antimony sulfide with good crystallinity, the method comprising the following steps:

[0096] S1, sulfur salt dissolution

[0097] Mix 60g of ammonium sulfide and 10g of antimony oxide evenly and place them in a dissolving tank. Add pure water and stir at high speed until completely dissolved. Adjust the antimony concentration to 150g / L and then add CTAB dispersant. Mix evenly to obtain an antimony solution.

[0098] The high-speed stirring rate is 1300 rpm, and the stirring time is 20 min.

[0099] The amount of CTAB dispersant added is 1% of the mass of the antimony solution.

[0100] S2, Adjusting acidity

[0101] The antimony solution was placed in a constant temperature water bath and the temperature of the antimony solution was controlled at 30℃. The stirring speed was adjusted to 1000 rpm. While stirring, a peristaltic pump was turned on to slowly add a 60% acetic acid solution at a rate of 8 ml / min. The final pH was controlled to be 1. The reaction was continued for 5 hours to obtain a precipitate.

[0102] S3, Filtration and Calcination

[0103] The precipitate obtained from S2 was filtered out and washed three times with anhydrous ethanol, then dried at a low temperature of 40°C for 24 hours to obtain antimony sulfide particles. The antimony sulfide particles were placed in a tube furnace, and under argon protection, the high-purity argon gas inside the tube was completely purged to maintain a pressure of 1 MPa. The furnace was then calcined at 400°C for 1 hour to obtain well-crystallized powdered nano-antimony sulfide with a weight of 11.4 g and a yield of 97.94%.

[0104] The nano-antimony sulfide materials from Examples 1-3 were used to prepare sodium-ion battery anode active materials, and their cycle life was tested. The specific methods are as follows:

[0105] Nano-antimony sulfide was uniformly mixed with a conductive agent (conductive carbon black) and a binder (PVDF) at a mass ratio of 7:2:1 and then dispersed in N-methyl-2-pyrrolidone (NMP) to prepare an electrode slurry. This slurry was then coated onto copper foil, dried at 60°C for 5 hours, rolled, sliced, and finally vacuum dried at 120°C for 12 hours to obtain the electrode sheet. The loading of antimony sulfide active material on the electrode sheet was 1-1.5 mg / cm³. 2 .

[0106] In an argon-filled glove box, CR2025 button cells were assembled using the obtained electrode sheet as the working electrode and the sodium sheet as the counter electrode. The electrolyte was a propylene carbonate (PC) solution containing 1 mol / L NaPF6 and 10 vol% fluoroethylene carbonate (FEC), and the separator was a Whatman glass fiber filter membrane. The assembled button cells were subjected to constant current charge-discharge tests on a charge-discharge tester. The voltage test range was 0.01–2.5 V. The cycle performance test procedure was to first perform 200 cycles at a current of 100 mA / g, and then perform long-term cycling tests at a 2C current, recording the changes in the specific capacity of the cells during the cycles.

[0107] from Figure 2 , Figure 3 It can be seen that the powdered antimony sulfide nanoparticles obtained after calcination have a more uniform particle size distribution, indicating that the uncalcined antimony sulfide particles are amorphous, while the calcined antimony sulfide nanoparticles have a crystallization direction; from Figure 4 , Figure 5 It can be seen that the nano-antimony sulfide has a plate-like structure with needle-like edges and good dispersibility; from Figure 6It can be seen that the specific capacity of antimony sulfide nanoparticles used as the negative electrode active material for sodium-ion batteries remains basically unchanged after long-term cycling.

[0108] Unless otherwise specified, all percentages mentioned in this invention are mass percentages, all ratios are mass ratios, and all raw materials are commercially available.

[0109] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing antimony sulfide with good crystallinity, characterized in that, The preparation method comprises the following steps: S1, sulfur salt dissolution: uniformly mix the sulfide salt and antimony oxide in proportion, and then add pure water after placing in a dissolving tank, and completely dissolve under high-speed stirring, and then add a dispersing agent after adjusting the antimony concentration, and then uniformly mix to obtain an antimony solution; the dispersing agent in S1 is one or more of ethylene glycol, PVP and CTAB, and the addition amount is 1-10% of the mass of the antimony solution; S2, adjusting acidity: control the temperature of the antimony solution to be 0-30℃, slowly add an acid solution while stirring, control the end point pH, continue to stir for 1-6h to obtain a precipitate; the end point pH in S2 is 1-9; S3, filtering and calcining: filter out the precipitate obtained in S2, wash with anhydrous ethanol for three times, and then dry at low temperature to obtain antimony sulfide particles; calcine the antimony sulfide particles under the condition of inert gas protection to obtain nanometer antimony sulfide with good crystallinity; the calcining temperature in S3 is 150-400℃, and the calcining time is 1-5h.

2. The method of claim 1, wherein the method is characterized by, The sulfide salt in S1 is one of sodium sulfide, potassium sulfide or ammonium sulfide, and the mass ratio of the sulfide salt to antimony oxide is 2-8:

1.

3. The method of claim 1, wherein the method is characterized by, The antimony concentration in S1 is 50-300g / L.

4. The method of claim 1, wherein the method is characterized by, The acid of the acid solution in S2 is one or more of hydrochloric acid, acetic acid, oxalic acid and citric acid.

5. The method of claim 1, wherein the method is characterized by, The mass fraction of the acid solution in S2 is 20-70%, and the addition rate is 2-10ml / min.

6. The method of claim 1, wherein the method is characterized by, The stirring rate in S2 is 400-1200rpm, and the stirring reaction time is 1-6h.

7. The method of claim 1, wherein the method is characterized by, The calcining pressure in S3 is 0.5-2MPa; The inert gas is one of nitrogen or argon.

8. The use of nano antimony sulfide prepared by the method for preparing nano antimony sulfide with good crystallinity according to any one of claims 1-7, characterized in that, The nanometer antimony sulfide is used for sodium ion battery negative active material.

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