Preparation method and device of metal particles

Abstract

The invention relates to a preparation method and device of metal particles, and the preparation method is carried out in an inert atmosphere and comprises the following steps: 1) placing a metal block in a solvent A; (2) heating the mixture obtained in the step (1), wherein the heating temperature is (the melting point Tm + 2 DEG C of the metal block)-(the melting point Tm + 50 DEG C of the metal block); 3) performing ultrasonic treatment on the heated mixture; and 4) standing and cleaning. The method has the advantages that the operation is simple, a metal block is molten in a heating mode, the molten metal can be granulated and uniformly dispersed in a solution through ultrasonic treatment in the solution, and finally the metal micron particles are formed. And the sizes of the metal particles are regulated and controlled by controlling the ultrasonic treatment time. Impurities are removed through standing cleaning treatment, and meanwhile the size distribution of metal particles can be adjusted in a standing mode. The preparation is performed in an inert atmosphere, and the product is placed in an organic solvent, so that the contact of metal with air and water is reduced, and the storage time of metal particles is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of preparation of metal particles, and in particular relates to a method and device for preparing metal particles for batteries. Background Art

[0002] Sodium metal particles are an excellent additive that can be used in sodium ion batteries to increase the capacity and first coulombic efficiency of sodium ion batteries. At present, sodium metal particles can be obtained by stirring a molten sodium metal block. However, the small sodium metal particles prepared by this method are large in size and have a wide size distribution, which reduces the use effect of the sodium metal particles. In addition, sodium metal has active chemical properties and is easy to react with oxygen and moisture in the air, and even cause explosions, which increases the difficulty of preparing and storing small sodium metal particles. Therefore, it is necessary to improve the existing technology invention and provide a simple and easy-to-operate method to prepare small sodium metal particles with small particle size, narrow size distribution and easy storage. Summary of the invention

[0003] The purpose of the present invention is to provide a method and device for preparing metal particles, which can prepare small-sized (micrometer-level) metal particles with uniform size distribution, and during the preparation process, reduce the contact between metal and air and water, and extend the storage time of metal particles, especially active metal particles, in an air environment.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for preparing metal particles comprises the following steps:

[0006] 1) placing the metal block in solvent A;

[0007] 2) heating the mixture obtained in step 1);

[0008] 3) subjecting the heated mixture to ultrasonic treatment;

[0009] 4) Let it sit and clean.

[0010] The preparation method is carried out in an inert atmosphere, and the inert atmosphere is one or more of nitrogen, argon and helium.

[0011] The metal block is sodium or tin.

[0012] The moisture content of the solvent A is ≤0.05wt%, the oxygen content is ≤0.05wt%, and the solvent A is an organic solvent;

[0013] The organic solvent is one or more of pyridine, ethylenediamine, acetic acid, chlorobenzene, N,N-dimethylaniline, ethylene glycol, dimethyl sulfoxide, toluene, trichloroacetic acid, N,N-dimethylformamide, mineral oil, polyethylene glycol, benzyl alcohol, ethyl benzoate, N-methylpyrrolidone, diphenyl ether, and dodecane.

[0014] The concentration of the metal blocks in the mixture is 5wt% to 50wt%.

[0015] The heating temperature in step 2) is (the melting point T of the metal block m +2℃)~(melting point of metal block T m +50℃).

[0016] The ultrasonic treatment time in step 3) is 3 to 120 minutes.

[0017] The standing time described in step 3) is 5 to 48 hours.

[0018] The cleaning described in step 4) is cleaning with solvent B, the water content in solvent B is ≤0.05wt%, the oxygen content is ≤0.05wt%, and solvent B is an organic solvent; the organic solvent is one or more of benzene, toluene, xylene, n-hexane, pentane, hexane, octane, dichloromethane, chloroform, and kerosene.

[0019] A device for preparing metal particles comprises a heater, a container, a thermometer, an ultrasonic generator, a liquid replenishing device, a liquid pipette and a liquid suction device, wherein the container is provided with an ultrasonic generator, the thermometer is arranged in the container, and a probe of the thermometer is immersed in a solvent A in the container, the liquid replenishing device is arranged above the liquid level of the solvent A in the container, one end of the liquid pipette is connected to the liquid suction device, and the other end is immersed below the liquid level of the solvent A in the container.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention is simple to operate. The metal block is melted by heating. Ultrasound in the solution can granulate the molten metal and evenly disperse it in the solution to finally form metal micron particles. The size of the metal particles can be regulated by controlling the time of ultrasonic treatment. Impurities can be removed by static cleaning treatment, and the size distribution of the metal particles can also be adjusted by static method. The preparation is carried out in an inert atmosphere, and the product is placed in an organic solvent, which reduces the contact between the metal and air and water, prolongs the storage time of the metal particles, especially the active metal particles, in the air environment, reduces the risk of ignition and explosion of the active metal, and is convenient for transportation and subsequent use.

[0022] 2. The present invention controls the heating temperature of the metal block to be higher than the melting point of the metal block and lower than the boiling point of the solvent A, and the heating temperature satisfies (the melting point T m+2℃)~(melting point of metal block T m +50℃). If the heating temperature is too low, the heating time will be too long, prolonging the preparation process, or the metal will not be easily melted or will not melt completely, resulting in uneven distribution of metal particle size; if the heating temperature is too high, the solvent will evaporate easily, affecting the concentration of the metal solution.

[0023] 3. The present invention can granulate the molten metal in the solution by ultrasound, and evenly disperse it in the solution, and finally form metal micron particles. And the time of ultrasound treatment is controlled within 3 to 120 minutes. If the ultrasound time is short, the metal particle size is large, and if the ultrasound time is extended, the metal particle size becomes smaller. However, if the ultrasound time is too short, the molten metal is not completely granulated and the size distribution is uneven; if the ultrasound time is too long, it consumes too much time and energy but the gain is not obvious.

[0024] 4. The present invention removes impurities through static cleaning treatment, and the static method can also adjust the size distribution of metal particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention.

[0026] In the figure: 1-heater 2-metal block 3-container 4-thermometer 5-solvent A 6-ultrasonic generator 7-liquid replenishing device 8-solvent B 9-pipette 10-liquid aspiration device. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0028] The entire metal particle preparation process is carried out under an inert atmosphere, which is one or more of nitrogen, argon, and helium. The specific metal particle preparation method includes the following steps:

[0029] 1) placing a metal block in solvent A, wherein the concentration of the metal block in the mixture is 5wt% to 50wt%, preferably 10wt% to 35wt%; 15wt% to 25wt%.

[0030] The metal block is sodium or tin.

[0031] The moisture content in solvent A is ≤0.05wt%, the oxygen content is ≤0.05wt%, and the boiling point of the organic solvent is higher than the melting point of the metal block;

[0032] The organic solvent is one or more of pyridine, ethylenediamine, acetic acid, chlorobenzene, N,N-dimethylaniline, ethylene glycol, dimethyl sulfoxide, toluene, trichloroacetic acid, N,N-dimethylformamide, mineral oil, polyethylene glycol, benzyl alcohol, ethyl benzoate, N-methylpyrrolidone, diphenyl ether, and dodecane. The mineral oil can be kerosene or liquid paraffin.

[0033] 2) heating the mixture obtained in step 1);

[0034] The heating temperature is (the melting point of the metal block T m +2℃)~(melting point of metal block T m +50℃), preferably (T m +3℃)~(T m +30℃), (T m +5℃)~(T m +10℃). Heating makes the metal block melt. If the heating temperature is too low, it will lead to too long heating time, prolonging the preparation process, or make the metal difficult to melt or incompletely melt, resulting in uneven distribution of metal particle size; if the heating temperature is too high, it will easily lead to solvent volatilization, affecting the concentration of the metal solution.

[0035] 3) subjecting the mixture to ultrasonic treatment after it has reached the heating temperature and melted;

[0036] The ultrasonic treatment time is 3 to 120 minutes, preferably 10 to 80 minutes, 20 to 40 minutes. Ultrasonication in the solution can granulate the molten metal, evenly disperse it in the solution, and finally form metal micron particles. Ultrasonic treatment can adjust the size of metal particles. If the ultrasonic time is short, the metal particle size is large, and if the ultrasonic time is extended, the metal particle size becomes smaller. However, if the ultrasonic time is too short, the molten metal is not completely granulated and the size distribution is uneven; if the ultrasonic time is too long, it consumes too much time and energy but the gain is not obvious.

[0037] 4) After the ultrasonic treatment is completed, the heating is stopped and the metal particle solution is allowed to stand for cleaning, that is, the metal particle solution is allowed to stand for a period of 5 to 48 hours, preferably 10 to 36 hours, 20 to 28 hours; after the standing is completed, the solid metal particles deposited at the bottom of the container are retained, the liquid is removed, and then the solvent B is added to the retained solid metal particles until the solvent B completely covers the solid metal particles.

[0038] The moisture content of solvent B is ≤0.05wt%, and the oxygen content is ≤0.05wt%. The organic solvent is one or more of benzene, toluene, xylene, n-hexane, pentane, hexane, octane, dichloromethane, chloroform, and kerosene.

[0039] Impurities can be removed by static cleaning, and the size distribution of metal particles can also be adjusted by static cleaning. The larger the metal particle size, the faster it will settle to the bottom of the container; the smaller the metal particle size, the easier it will be to suspend in the liquid and the slower it will settle to the bottom of the container. Therefore, by adjusting the length of the static cleaning time, metal particles that are too large or too small can be removed to make the size distribution more uniform. In addition, even if solvent A and solvent B are the same solvent, a static cleaning step is required to remove solvent A.

[0040] See Figure 1 The preparation device of metal particles includes a heater 1, a container 3, a thermometer 4, an ultrasonic generator 6, a liquid replenishing device 7, a liquid suction tube 9, and a liquid suction device 10. The heater 1 is used to heat the container 3. The solvent A5 is contained in the container 3. The metal block 2 is placed in the solvent A5. The ultrasonic generator 6 is placed at the center of the container 3, and the head is immersed in the solvent during operation. The thermometer 4 is arranged in the container 3, and the probe of the thermometer 4 is immersed in the solvent A5 in the container 3. The liquid replenishing device 7 is arranged above the liquid level of the solvent A5 in the container 3. The liquid replenishing device 7 contains the solvent B8. The liquid replenishing device 7 can be a funnel structure, and a valve can be installed at the bottom of the funnel to control whether the solvent B8 is added. One end of the liquid suction tube 9 is connected to the liquid suction device 10, and the other end is immersed below the liquid level of the solvent A5 in the container 3. The liquid suction device 10 can be a liquid storage tank with a pump for absorbing and storing liquid. When preparing sodium or tin metal particles, first put solvent A5 into container 3, then put metal block 2 into solvent A5, use heater 1 to heat container 3 and then heat solvent A5 and metal block 2, heat to melt metal block 2, use thermometer 4 to monitor system temperature, after reaching heating temperature and metal melts, turn on ultrasonic generator 6, ultrasonicate granulates molten metal, during heating and ultrasonicate process, pipette 9 and rehydration device 7 should be placed above liquid surface; after ultrasonicate is completed, stop heating, lift ultrasonic generator 6 and place above liquid surface, start to let metal particle solution stand, let target metal particles be deposited at the bottom of container 3; after standing, insert pipette 9 placed above liquid surface under liquid surface, retain metal particles deposited at the bottom of container 3, turn on pipette 10, remove solvent A5, after solvent A5 is removed, turn off pipette 10, lift pipette 9, use rehydration device 7 to add solvent B8, until solvent B8 completely covers the deposited metal particles.

[0041] The removal of solvent A5 can be confirmed by observation. There are two purposes for removing solvent A: one is to remove impurities that may be generated during the operation, and the other is to remove metal particles of too small size suspended in solvent A. Those metal particles suspended in solvent A are sucked away along with solvent A.

[0042] See Table 1 and Table 2 for the embodiments and comparative examples.

[0043] Table 1 Introduction to the implementation method of the embodiment and the corresponding metal particle size

[0044]

[0045] In Table 1, Example 1: In a nitrogen environment, a sodium metal block is placed in mineral oil, the sodium metal block content is 15wt%, then the mixture is heated to 105°C, after the sodium metal melts at the heating temperature, the mixture is ultrasonically treated at this temperature, the ultrasonic treatment time is 8min, after the ultrasonic treatment is completed, the heating is stopped, the mixture is allowed to stand for 24h, after the standing is completed, the metal particles deposited at the bottom of the container are retained, the solvent is removed, and finally, n-hexane is added to the deposited metal particles until the n-hexane completely covers the metal particles. The size of the metal particles obtained in this embodiment is 30±7μm.

[0046] Example 2: Compared with Example 1, other conditions remain unchanged, and the ultrasonic treatment time is changed to 15 minutes. The size of the metal particles finally obtained is 16±5 μm.

[0047] Example 3: Compared with Example 1, other conditions remain unchanged, and the ultrasonic treatment time is changed to 30 minutes. The size of the metal particles finally obtained is 8±2 μm.

[0048] Example 4: In an argon environment, a tin metal block is placed in polyethylene glycol, the tin metal block content is 35wt%, then the mixture is heated to 240°C, and after the tin metal melts at the heating temperature, the mixture is ultrasonically treated at this temperature, the ultrasonic treatment time is 60min, after the ultrasonic treatment is completed, the heating is stopped, and the mixture is allowed to stand for 18h, after the standing is completed, the metal particles deposited at the bottom of the container are retained, the solvent is removed, and finally, toluene is added to the deposited metal particles until the toluene completely covers the metal particles. The size of the metal particles obtained in this example is 4±1μm.

[0049] Table 2 Comparative Example Implementation Method Brief Introduction and Corresponding Metal Particle Size

[0050]

[0051] Comparative Example 1: In a nitrogen environment, a sodium metal block is placed in mineral oil, the sodium metal block content is 15wt%, and then the mixture is heated to 105°C. After the sodium metal melts at the heating temperature, the mixture is stirred at this temperature for 8 minutes. The metal particles obtained in this comparative example have a size of 500±200μm.

[0052] Comparative Example 2: In a nitrogen environment, a sodium metal block is placed in mineral oil, the sodium metal block content is 15wt%, then the mixture is heated to 80°C, and after reaching the heating temperature, the mixture is ultrasonically treated at this temperature, the ultrasonic treatment time is 8min, and after the ultrasonic treatment is completed, the heating is stopped, and the mixture is allowed to stand for 24h. After the standing is completed, the metal deposited at the bottom of the container is retained, the solvent is removed, and finally, n-hexane is added to the deposited metal until the n-hexane completely covers the metal. In this comparative example, due to the low heating temperature, the melting point of the metal is not reached, and no metal micron particles are formed.

[0053] It can be seen from Examples 1-4 that the method is applicable to metal sodium and tin. By comparison with Examples 1-3, it can be seen that the size of the metal particles can be adjusted by controlling the ultrasonic treatment time, and the size of the metal particles can be reduced by appropriately extending the ultrasonic treatment time.

[0054] By comparing Comparative Example 1 with Example 1, it can be seen that if the method of the present invention is not used to prepare metal micron particles, the product size is larger and the size distribution is more uneven. By comparing Comparative Example 2 with Example 1, it can be seen that if the parameters of the present invention are not used to prepare metal micron particles, operation failure may occur.

[0055] The present invention is simple to operate. A heating method is used to melt a metal block. Ultrasound is used in a solution to granulate the molten metal and evenly disperse it in the solution to eventually form metal micron particles. The size of the metal particles is adjusted by controlling the time of ultrasonic treatment, so that the size of the metal particles can be controlled. Impurities and oversized or undersized metal particles are removed by static cleaning treatment, so that the size distribution of the metal particles is more uniform. The operation is prepared in an inert atmosphere, and the product is placed in an organic solvent, which reduces the contact between the metal and air and water, prolongs the storage time of the metal particles, especially the active metal particles, in the air environment, reduces the risk of ignition and explosion of the active metal, and is convenient for transportation and subsequent use.

Claims

1. A method for preparing metal particles, characterized in that: The following steps are involved: 1) Place the metal block in solvent A; 2) heating the mixture obtained in step 1); 3) subjecting the heated mixture to ultrasonic treatment; 4) Let it sit and clean.

2. The method for preparing metal particles according to claim 1, characterized in that: The preparation method is carried out in an inert atmosphere, and the inert atmosphere is one or more of nitrogen, argon and helium.

3. The method for preparing metal particles according to claim 1, characterized in that: The metal block is sodium or tin.

4. The method for preparing metal particles according to claim 1, characterized in that: The moisture content of the solvent A is ≤0.05wt%, the oxygen content is ≤0.05wt%, and the solvent A is an organic solvent; The organic solvent is one or more of pyridine, ethylenediamine, acetic acid, chlorobenzene, N,N-dimethylaniline, ethylene glycol, dimethyl sulfoxide, toluene, trichloroacetic acid, N,N-dimethylformamide, mineral oil, polyethylene glycol, benzyl alcohol, ethyl benzoate, N-methylpyrrolidone, diphenyl ether, and dodecane.

5. The method for preparing metal particles according to claim 1, characterized in that: The concentration of the metal blocks in the mixture is 5wt% to 50wt%.

6. The method for preparing metal particles according to claim 1, characterized in that: The heating temperature in step 2) is (the melting point T of the metal block m +2℃)~(melting point of metal block T m +50℃).

7. The method for preparing metal particles according to claim 1, characterized in that: The ultrasonic treatment time in step 3) is 3 to 120 minutes.

8. The method for preparing metal particles according to claim 1, characterized in that: The standing time described in step 4) is 5 to 48 hours.

9. The method for preparing metal particles according to claim 1, characterized in that: The cleaning described in step 4) is cleaning with solvent B, the water content in solvent B is ≤0.05wt%, the oxygen content is ≤0.05wt%, and solvent B is an organic solvent; the organic solvent is one or more of benzene, toluene, xylene, n-hexane, pentane, hexane, octane, dichloromethane, chloroform, and kerosene.

10. A device for preparing metal particles for implementing the method according to any one of claims 1 to 9, characterized in that: The invention comprises a heater, a container, a thermometer, an ultrasonic generator, a liquid replenishing device, a liquid pipette and a liquid suction device. The heater is used to heat the container. The ultrasonic generator is arranged in the container. The thermometer is arranged in the container, and the probe of the thermometer is immersed in the solvent A in the container. The liquid replenishing device is arranged above the liquid level of the solvent A in the container. One end of the liquid pipette is connected to the liquid suction device, and the other end is immersed below the liquid level of the solvent A in the container.

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