A method for synthesizing Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-05
- Publication Date
- 2026-08-14
AI Technical Summary
但采用基本合成工艺的普鲁士蓝类似物正极材料存在比容量低、反应时间长、易氧化等不同的问题
[0021]本发明整个过程中在无氧条件下反应，减少了反应过程中亚铁离子的氧化情况，进而保证了反应合成后普鲁士蓝晶格的完整性，提高了普鲁士蓝正极材料的比容量。
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Figure CN122561978A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cathode materials for sodium-ion batteries, and particularly to a method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure. Background Technology
[0002] With the technological development of energy storage systems and power battery systems, and the structural shortage of lithium resources due to mining conditions, technological limitations, geopolitical factors, etc., sodium-ion batteries have become one of the most watched emerging batteries. Among the different cathode materials of sodium-ion batteries, Prussian blue analog cathode materials have attracted much attention due to their high safety, low cost, and stable structure.
[0003] The basic synthesis process of Prussian blue analog cathode materials typically involves reacting sodium ferrocyanide solution, iron salt solution, and a certain amount of inhibitor solution using different dropwise addition methods. However, Prussian blue analog cathode materials synthesized using this basic process suffer from various problems, including low specific capacity, long reaction time, and susceptibility to oxidation. Therefore, a process is needed to shorten the reaction time under anaerobic conditions and produce Prussian blue analog cathode materials with high specific capacity and stable cycling performance. Summary of the Invention
[0004] This invention proposes a method for synthesizing Prussian blue analog cathode materials for sodium-ion batteries under high temperature and high pressure. The method mainly involves dissolving sodium citrate and iron salts in an oxygen-free, high-pressure, sealed container to form solution A, and dissolving sodium ferrocyanide in the same container to form solution B. Solution C is an aqueous solution prepared under oxygen-free, sealed, high temperature and high pressure. Solutions A and B are simultaneously added dropwise to solution C for reaction, aging, filtration, washing, and vacuum drying to prepare the Prussian blue analog cathode material. The Prussian blue analog cathode material synthesized by this method exhibits high specific capacity, short processing time, good cycle stability, and uniform particle size.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows:
[0006] A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure includes the following steps:
[0007] (1) Add sodium citrate and iron salt solid powder to a sealed container A and evacuate it. Use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Then stir it and label it as solution A.
[0008] (2) Add sodium ferrocyanide solid powder to a sealed container B and evacuate it. Use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Stir and label it as solution B.
[0009] (3) Vacuum the sealed container C, use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Label it as solution C.
[0010] (4) Pressurize solutions A and B to 0.1 MPa-1.0 MPa respectively, pressurize solution C to 0-0.9 MPa, heat to 80℃-120℃, and stir at a speed of 200 r / min-1000 r / min. Maintain the pressure difference between solutions A and B and solution C at 0.05 MPa-0.3 MPa. Add solutions A and B to solution C by controlling the pressure difference and flow meter. The addition time is 40 min-600 min. After the addition is completed, continue stirring for 3 h-12 h. During this process, keep the temperature and pressure constant to obtain a mixed solution.
[0011] (5) Stop stirring the mixed solution and cool and age it. Filter under positive pressure to obtain the precipitate. The pressure range is 0.1MPa-0.5MPa. Vacuum the sealed container C. The vacuum range is -50.0KPa to -90.0KPa. Use the vacuum to draw in oxygen-free deionized water and fill it with inert gas to restore it to normal pressure. Wash and stir. The stirring speed is 200r / min-1000r / min and the stirring time is 5min-30min. After stopping the stirring, filter under positive pressure to obtain the washed precipitate. The pressure range is 0.1MPa-0.5MPa. Wash 1-3 times. After washing, quickly transfer it to a vacuum oven for heating and drying under inert gas protection to obtain the positive electrode material.
[0012] Further, in step (1), the amount of sodium citrate added is 1 to 5 times the amount of iron salt, the amount of iron salt is 24 mmol to 72 mmol, and the iron salt is ferrous sulfate with a concentration range of 0.01 mol / L to 0.3 mol / L.
[0013] Furthermore, the inert gas in steps (1), (2), and (3) is one or both of nitrogen and argon.
[0014] Furthermore, in steps (1), (2), and (3), the vacuum setting value is not higher than -90.0 kPa.
[0015] Furthermore, the stirring in steps (1) and (2) is carried out by stirring in an oil bath at 50℃-90℃ for 1h-24h, with a stirring speed of 200r / min-1000r / min.
[0016] Furthermore, the volume of deionized water in steps (1) and (2) is 300mL-1000mL; the volume of deionized water in step (3) is 100mL-500mL; and the volume of deionized water in step (5) is 200mL-600mL.
[0017] Furthermore, the cooling and aging time in step (5) is 3h-12h, and the temperature is cooled to below 25℃.
[0018] Furthermore, in step (5), the vacuum setting value is not higher than -90.0KPa. In the first stage, the drying is carried out at 90℃-120℃ for 12h-24h to remove surface adsorbed water; in the second stage, the drying is carried out at 160℃-200℃ for 12h-24h to remove some of the crystal water.
[0019] An application of a Prussian blue analogue cathode material for sodium-ion batteries, used as a positive electrode active material in sodium-ion batteries.
[0020] The beneficial effects of this invention are:
[0021] The entire process of this invention is carried out under anaerobic conditions, which reduces the oxidation of ferrous ions during the reaction, thereby ensuring the integrity of the Prussian blue lattice after synthesis and improving the specific capacity of the Prussian blue cathode material.
[0022] The synthesis process of this invention is carried out under high temperature and high pressure conditions, which shortens the synthesis time for the same yield and capacity while ensuring the orderly growth of the Prussian blue lattice.
[0023] This invention uses differential pressure for dripping and a flow meter for flow control, which, compared to peristaltic pump dripping, ensures the uniformity of solution dripping and improves the particle size consistency of the synthesized Prussian blue material.
[0024] Other features and advantages of the present invention will be described in detail in part in the following detailed description. Attached Figure Description
[0025] Figure 1 This is a flowchart of the synthesis process;
[0026] Figure 2 This is the first charge-discharge specific capacity curve of Example 1;
[0027] Figure 3 This is the charge-discharge specific capacity curve for the first cycle of Example 2;
[0028] Figure 4 This is the charge-discharge specific capacity curve for the first cycle of Example 3;
[0029] Figure 5 This is the first charge-discharge specific capacity curve of the comparative model. Detailed Implementation
[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0031] Example 1
[0032] A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure, such as... Figure 1 As shown, it includes the following steps:
[0033] Add 36 mmol of ferrous sulfate and 174 mmol of sodium citrate to a sealed container A, and evacuate the container. Set the vacuum level to -98.5 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 80°C for 1 hour with a stirring speed of 600 r / min.
[0034] Add 24 mmol of sodium ferrocyanide to a sealed container B, and evacuate the container. Set the vacuum level to -98.5 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 80°C for 1 hour with a stirring speed of 600 r / min.
[0035] Vacuum the sealed container C until the vacuum level is no higher than -98.5 kPa. Then, use the vacuum to draw in 250 mL of oxygen-free deionized water and fill it with nitrogen to restore it to normal pressure.
[0036] Solutions A and B were pressurized to 0.4 MPa, and solution C was pressurized to 0.3 MPa. The mixture was heated to 120°C and stirred at a speed of 600 rpm. Solutions A and B were added to solution C using pressure differential and a flow meter, at a flow rate of 15 mL / min over a time of 40 min. After the addition was complete, solution C was stirred for another 3 h, maintaining constant temperature and pressure throughout this process.
[0037] Stirring of solution C was stopped, and the solution was cooled and aged for 3 hours. The pressure in sealed container C was increased to 0.3 MPa, and the precipitate was obtained through positive pressure filtration. Container C was then evacuated to a vacuum range of -60.0 kPa, and 400 mL of oxygen-free deionized water was drawn in using the vacuum. Inert gas was then introduced to restore the pressure to normal. The mixture was washed and stirred at 500 r / min for 10 minutes. After stirring was stopped, the pressure in sealed container C was increased to 0.3 MPa, and the washed precipitate was obtained through positive pressure filtration. The precipitate was washed once and then quickly transferred to a vacuum oven for heating and drying. The heating and drying process consisted of two stages: in the first stage, the vacuum oven temperature was set to 100℃, the vacuum level was set not to exceed -95.0 kPa, and the drying time was 12 hours; in the second stage, the vacuum oven temperature was set to 180℃, the vacuum level was set not to exceed -95.0 kPa, and the drying time was 12 hours. The Prussian blue cathode material was finally obtained.
[0038] Example 2
[0039] A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure includes the following steps:
[0040] Add 36 mmol of ferrous sulfate and 174 mmol of sodium citrate to a sealed container A, and evacuate the container. Set the vacuum level to -95.0 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 50°C for 1 hour with a stirring speed of 600 r / min.
[0041] Add 24 mmol of sodium ferrocyanide to a sealed container B, and evacuate the container. Set the vacuum level to -95.0 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 50°C for 1 hour with a stirring speed of 600 r / min.
[0042] Vacuum the sealed container C until the vacuum level is no higher than -98.5 kPa. Then, use the vacuum to draw in 250 mL of oxygen-free deionized water and fill it with nitrogen to restore it to normal pressure.
[0043] Solutions A and B were pressurized to 0.2 MPa, while solution C was kept at atmospheric pressure. The solution was heated to 90°C and stirred at a speed of 600 r / min. Solutions A and B were added to solution C using pressure differential and a flow meter at a flow rate of 15 mL / min over a period of 40 min. After the addition was complete, solution C was stirred for another 3 h, maintaining constant temperature and pressure throughout the process.
[0044] Stirring of solution C was stopped, and the solution was cooled and aged for 3 hours. The pressure in sealed container C was increased to 0.3 MPa, and the precipitate was obtained through positive pressure filtration. Container C was then evacuated to a vacuum range of -60.0 kPa, and 400 mL of oxygen-free deionized water was drawn in using the vacuum. Inert gas was then introduced to restore the pressure to normal. The mixture was washed and stirred at 500 rpm for 10 minutes. After stirring was stopped, the pressure in sealed container C was increased to 0.3 MPa, and the washed precipitate was obtained through positive pressure filtration. The precipitate was washed once and then quickly transferred to a vacuum oven for heating and drying. The heating and drying process consisted of two stages: the first stage involved setting the vacuum oven temperature to 120°C and the vacuum level not exceeding -95.0 kPa for 12 hours; the second stage involved setting the vacuum oven temperature to 200°C and the vacuum level not exceeding -95.0 kPa for 12 hours, ultimately yielding the Prussian blue cathode material.
[0045] Example 3
[0046] A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure includes the following steps:
[0047] Add 36 mmol of ferrous sulfate and 174 mmol of sodium citrate to a sealed container A, and evacuate the container. Set the vacuum level to -90.0 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 60°C for 1 hour with a stirring speed of 600 r / min.
[0048] Add 24 mmol of sodium ferrocyanide to a sealed container B, and evacuate the container. Set the vacuum level to -90.0 kPa and stop. Add 600 mL of deionized water and purge the container with nitrogen to bring it to atmospheric pressure. Heat the container in an oil bath at 60°C for 1 hour with a stirring speed of 600 r / min.
[0049] Vacuum the sealed container C until the vacuum level is no higher than -98.5 kPa. Then, use the vacuum to draw in 250 mL of oxygen-free deionized water and fill it with nitrogen to restore it to normal pressure.
[0050] Solutions A and B were pressurized to 0.3 MPa, and solution C was pressurized to 0.2 MPa. The mixture was heated to 100°C and stirred at a speed of 600 r / min. Solutions A and B were added to solution C using a pressure differential and flow meter control at a flow rate of 15 mL / min over a period of 40 min. After the addition was complete, solution C was stirred for another 3 h, maintaining constant temperature and pressure throughout this process.
[0051] Stirring of solution C was stopped, and the solution was cooled and aged for 3 hours. The pressure in sealed container C was increased to 0.3 MPa, and the precipitate was obtained through positive pressure filtration. Container C was then evacuated to a vacuum range of -60.0 kPa, and 400 mL of oxygen-free deionized water was drawn in using the vacuum. Inert gas was then introduced to restore the pressure to normal. The mixture was washed and stirred at 500 rpm for 10 minutes. After stirring was stopped, the pressure in sealed container C was increased to 0.3 MPa, and the washed precipitate was obtained through positive pressure filtration. The precipitate was washed once and then quickly transferred to a vacuum oven for heating and drying. The heating and drying process consisted of two stages: the first stage involved setting the vacuum oven temperature to 110℃ and the vacuum level not exceeding -95.0 kPa for 12 hours; the second stage involved setting the vacuum oven temperature to 190℃ and the vacuum level not exceeding -95.0 kPa for 12 hours, ultimately yielding the Prussian blue cathode material.
[0052] Comparative Example
[0053] A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure includes the following steps:
[0054] Add 36 mmol of ferrous sulfate and 174 mmol of sodium citrate to container A, and add deionized water to a total volume of 600 mL. Stir at 600 rpm.
[0055] Add 24 mmol of sodium ferrocyanide to container B, and add deionized water to a total volume of 600 mL. Stir at 600 rpm.
[0056] Add 250 mL of deionized water to container C.
[0057] Set the stirring speed of solution C to 600 r / min. Add solutions A and B to solution C separately using a peristaltic pump at a flow rate of 1.25 mL / min for 480 min. After the addition is complete, continue stirring solution C for 3 h.
[0058] Stirring of solution C was stopped, and the mixture was cooled and aged for 3 hours. The precipitate was obtained by vacuum filtration and quickly transferred to a vacuum oven for heating and drying. The heating and drying process consisted of two stages: in the first stage, the vacuum oven temperature was set at 120℃, the vacuum level was set not higher than -95.0 kPa, and the heating and drying time was 12 hours; in the second stage, the vacuum oven temperature was set at 200℃, the vacuum level was set not higher than -95.0 kPa, and the heating and drying time was 12 hours, ultimately yielding the Prussian blue cathode material.
[0059] Figure 2 This is the charge-discharge specific capacity curve of Example 1. Figure 3 This is the charge-discharge specific capacity curve for the first cycle of Example 2. Figure 4 This is the charge-discharge specific capacity curve for the first cycle of Example 3. Figure 5 This is the first charge-discharge specific capacity curve of the comparative model.
[0060] Table 1 shows the specific capacity of the Prussian blue cathode materials prepared in Examples 1, 2, 3 and the comparative examples, the specific capacity of the first charge at 1C rate, the specific capacity of the first discharge at 1C rate, the capacity retention rate after 100 cycles at 1C rate, and the drop reaction time.
[0061] Example 1 149.21mAh / g 147.47mAh / g 91.22% 40min Example 2 146.41mAh / g 143.81mAh / g 92.35% 40min Example 3 148.88mAh / g 146.99 mAh / g 91.74% 40min Comparative Example 137.49mAh / g 135.81mAh / g 90.53% 480min
[0062] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A method for synthesizing a Prussian blue analogue cathode material for sodium-ion batteries under high temperature and high pressure, characterized in that, Includes the following steps: (1) Add sodium citrate and iron salt solid powder to a sealed container A and evacuate it. Use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Then stir it and label it as solution A. (2) Add sodium ferrocyanide solid powder to a sealed container B and evacuate it. Use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Stir and label it as solution B. (3) Vacuum the sealed container C, use the vacuum to draw in oxygen-free deionized water, and fill it with inert gas to restore it to normal pressure. Label it as solution C. (4) Pressurize solutions A and B to 0.1 MPa-1.0 MPa respectively, pressurize solution C to 0-0.9 MPa, heat to 80℃-120℃, and stir at a speed of 200 r / min-1000 r / min. Maintain the pressure difference between solutions A and B and solution C at 0.05 MPa-0.3 MPa. Add solutions A and B to solution C by controlling the pressure difference and flow meter. The addition time is 40 min-600 min. After the addition is completed, continue stirring for 3 h-12 h. During this process, keep the temperature and pressure constant to obtain a mixed solution. (5) Stop stirring the mixed solution and cool and age it. Filter under positive pressure to obtain the precipitate. The pressure range is 0.1MPa-0.5MPa. Vacuum the sealed container C. The vacuum range is -50.0KPa to -90.0KPa. Use the vacuum to draw in oxygen-free deionized water and fill it with inert gas to restore it to normal pressure. Wash and stir. The stirring speed is 200r / min-1000r / min and the stirring time is 5min-30min. After stopping the stirring, filter under positive pressure to obtain the washed precipitate. The pressure range is 0.1MPa-0.5MPa. Wash 1-3 times. After washing, quickly transfer it to a vacuum oven for heating and drying under inert gas protection to obtain the positive electrode material.
2. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, In step (1), the amount of sodium citrate added is 1 to 5 times the amount of iron salt, the amount of iron salt is 24 mmol to 72 mmol, and the iron salt is ferrous sulfate with a concentration range of 0.01 mol / L to 0.3 mol / L.
3. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, The inert gas in steps (1), (2), and (3) is one or both of nitrogen and argon.
4. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, In steps (1), (2), and (3), the vacuum setting value should not be higher than -90.0 kPa.
5. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, The stirring in steps (1) and (2) is carried out by stirring in an oil bath at 50℃-90℃ for 1h-24h at a stirring speed of 200r / min-1000r / min.
6. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, In steps (1) and (2), the volume of deionized water is 300mL-1000mL; in step (3), the volume of deionized water is 100mL-500mL; and in step (5), the volume of deionized water is 200mL-600mL.
7. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, The cooling and aging time in step (5) is 3h-12h, and the temperature is cooled to below 25℃.
8. The method for synthesizing a Prussian blue analog cathode material for sodium-ion batteries under high temperature and high pressure according to claim 1, characterized in that, In step (5), the vacuum setting value is not higher than -90.0KPa. The first stage is drying at 90℃-120℃ for 12h-24h to remove surface adsorbed water; the second stage is drying at 160℃-200℃ for 12h-24h to remove some crystal water.
9. An application of a Prussian blue analogue cathode material for sodium-ion batteries, characterized in that, The Prussian blue analogue cathode material used in sodium-ion batteries is applied as the positive electrode active material.