Coating device for graphite negative electrode material

Abstract

The utility model provides a coating device for a graphite cathode material. The device comprises a fluidization unit and a stirring unit which are communicated with each other, the fluidization unit is arranged above the stirring unit; the fluidization unit comprises a fluidization cabin, a liquid inlet pipeline and a fluidizer; a first feeding hole and a first discharging hole are respectively formed in the top and the bottom of the fluidization cabin; the liquid inlet pipeline is arranged at the upper part in the fluidization cabin along the radial direction of the fluidization cabin; a plurality of atomizers with downward nozzles are arranged on the liquid inlet pipeline; the fluidizer is arranged at the lower part in the fluidization cabin along the radial direction of the fluidization cabin; a plurality of upward air outlets are formed in the fluidizer; the stirring unit comprises a coating kettle provided with a stirring element, a second feeding hole is formed in the top of the coating kettle, and the second feeding hole is connected with the first discharging hole. According to the coating device, the coating effect of the negative electrode material under the condition of low coating amount can be improved, so that the coating of the negative electrode material is more uniform; according to the coating device, the powder and the liquid-phase coating agent are mixed in a fluid form, and the treatment process is faster and more efficient.

Description

Technical Field

[0001] The utility model relates to a coating device for graphite anode materials. Background Technique

[0002] Lithium-ion batteries are widely used due to their advantages such as high specific energy, high working voltage, and long cycle life. Graphite has a good layered structure and is the main anode material for lithium-ion batteries.

[0003] Due to its relatively developed layered structure, the specific capacity of natural graphite can almost approach the theoretical value, but it has high anisotropy and poor rate performance. In the cycle, the layered structure of graphite is easily damaged, reducing the cycle performance.

[0004] Artificial graphite is the anode material with the highest market share at present. The various properties of artificial graphite are relatively balanced. Its cycle performance and rate performance are better than those of natural graphite. It has properties such as high tap density, long cycle life, and high rate. The demand in the fields of consumer electronics and new energy vehicles continues to rise. The carbon atoms inside artificial graphite particles are arranged radially. Lithium ions are inserted and extracted at the edge of graphite. During long-term cycling, the repeated entry and exit of lithium ions will cause the edge of the carbon layer to peel off or even deform, resulting in capacity attenuation. Therefore, optimizing the transmission channel of lithium ions in graphite becomes the key.

[0005] Although highly crystalline graphitized materials have performance advantages such as high first efficiency and excellent cycle performance, they will also cause problems such as swelling. Therefore, generally, an amorphous carbon layer is coated on the surface of graphite by liquid-phase or solid-phase carbonization deposition to improve the swelling problem during cycling. An appropriate coating amount will also improve the fast charging and rate performance; however, when the coating amount is too much, not only will the coating effect be affected, but its electrochemical performance will not be significantly improved.

[0006] The current market demand is for artificial graphite anode materials with high energy density, fast charging, and long cycle life. Therefore, on the basis of ensuring long cycle life, the performance requirements of long cycle life and high rate are balanced by reducing the coating amount; however, the problem of coating uniformity is also caused at the same time. A low coating amount is more likely to cause uneven coating, and some particles are not coated with amorphous carbon, resulting in the exposure of graphitized materials, further causing a decrease in kinetic performance and even problems such as lithium plating.

[0007] Common coating methods include mechanical mixing coating method and liquid-phase coating method. The coating effect of the mechanical mixing coating method is worse than that of the liquid-phase coating method. The mechanical mixing coating method also requires an additional asphalt mixing process, increasing the processing cost and the processing cycle. Most enterprises currently choose the liquid-phase coating method. The liquid-phase coating agent can be liquid-phase asphalt, resin, carbon nanotubes, etc. There are mainly the following several types of liquid-phase coating devices in the prior art:

[0008] The first method is to set an insulation layer on the inner wall of the cylinder of a traditional vibrating machine, and spray the liquid asphalt into the cylinder by means of a pressurized nozzle to maintain the coating temperature in the cylinder and set the nozzle to improve the coating uniformity of the liquid asphalt by spraying. This method ensures the coating temperature in the cylinder and can improve the coating effect to a certain extent, but a single nozzle is set at the upper end of the cylinder. For the demand of low coating amount, the nozzle sprays in a single direction, and internal stress is generated while the nozzle discharges the material quickly, and there is also the problem of uneven coating.

[0009] The second method is to set a heating device on the outer shell of the coated cylinder and an air flow distributor at the bottom. The high-pressure gas enters from the bottom and works together with the stirring blades in the cylinder to fully mix the powder and the coating agent. The uniformity of the coating is improved by the all-round flipping and jumping between the particles. This method of adding an air flow distributor evenly disperses the particles and avoids agglomeration and deposition between the particles. After the coating agent enters the cylinder through the feed port, the coating device rotates at high speed and throws the material on the cylinder wall under the action of centrifugal force. The adhesive coating material will still adhere to the cylinder wall, affecting the actual coating amount and thus the electrical properties of the final product.

[0010] The third type is a device that uses a mixing barrel and a coating vertical cylinder together, with an atomizing nozzle set at the top of the coating cylinder, and a pressurizer set to allow the coating agent to be sprayed out through the high-speed atomizer nozzle to achieve uniform coating. This device uses a pressure atomizer, and some organic polymers such as resin coating agents have high viscosity and large surface tension, which will affect the spray effect and lead to poor coating uniformity.

[0011] It can be seen that the above-mentioned coating devices cannot guarantee the coating uniformity of low coating amounts, so a highly uniform dispersion coating device is urgently needed to solve the shortcomings of the existing technology. Utility Model Content

[0012] In order to overcome the defect of uneven coating of negative electrode materials in the prior art, thus affecting the electrical performance of subsequent lithium-ion batteries. The utility model provides a coating device for graphite negative electrode materials; by cooperating with a fluidizing unit and a stirring unit, the problems of uneven material coating and poor coating effect under low coating amount are solved, and the coating device can improve the coating of graphite negative electrode materials and make the coating of negative electrode materials more uniform; the coating device of the present application mixes powder and liquid coating agent in the form of fluid, and the processing process is faster and more efficient.

[0013] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0014] The utility model provides a coating device for graphite negative electrode material, which comprises a fluidizing unit and a stirring unit which are interconnected; the fluidizing unit is arranged above the stirring unit;

[0015] The fluidization unit includes a fluidization chamber, a liquid inlet pipe, and a fluidizer; a first feed inlet and a first discharge outlet are respectively provided at the top and bottom of the fluidization chamber, and the first feed inlet is used for feeding powder; the liquid inlet pipe is arranged in the upper part of the fluidization chamber along the radial direction of the fluidization chamber, and a plurality of atomizers with openings facing downward are provided on the liquid inlet pipe for atomizing the liquid coating agent and then feeding it into the fluidization chamber; the fluidizer is arranged in the lower part of the fluidization chamber along the radial direction of the fluidization chamber, and a plurality of air outlets facing upward are provided on the fluidizer for making the mixture of powder and liquid coating agent in a fluidized state; the distance between the liquid inlet pipe and the fluidizer is 1 / 2 to 3 / 5 of the height of the fluidization chamber;

[0016] The stirring unit includes a coating kettle provided with a stirring element, and a second feed inlet is provided at the top of the coating kettle. The second feed inlet is connected to the first discharge outlet for communicating the fluidization chamber with the coating kettle.

[0017] In the present utility model, by arranging the atomizer on the liquid inlet pipe in the fluidization chamber and the air outlet of the fluidizer opposite to each other, a certain amount of powder and liquid coating agent can be in a high-speed fluidized state in the fluidization chamber, and can be effectively broken to prevent adhesion and agglomeration. At the same time, an internal circulation is formed to fully contact and achieve the purpose of uniform mixing; then, the mixed material enters the coating kettle, and through the stirring element, the mixing uniformity of the powder and the liquid coating agent is improved, overcoming the uneven mixing of the traditional mechanical mixing coating and its influence on the electrical properties of the final product.

[0018] In the present utility model, the coating device for the graphite negative electrode material can be used for the coating process of graphite; wherein, the graphite can be artificial graphite and / or natural graphite.

[0019] In the present utility model, the kettle body of the coating kettle can be in a cylindrical shape.

[0020] In some embodiments, the stirring element is arranged along the axis of the coating kettle and includes a stirring shaft, a U-shaped scraper, and a plurality of stirring rods arranged in parallel; a hollow connecting part is provided at the central part of each stirring rod, and each stirring rod is vertically sleeved on the stirring shaft through the connecting part; the U-shaped scraper is symmetrically connected to both ends of the stirring rod.

[0021] In a specific embodiment, the distance between the U-shaped scraper and the inner wall surface of the coating kettle is 3-5 mm; by arranging the U-shaped scraper, the material adhered to the inner wall of the coating kettle due to centrifugal force can be scraped off, and thus the uniform coating can be completed more efficiently.

[0022] In a specific embodiment, the number of the stirring rods is 1-3.

[0023] In a specific embodiment, the coating device includes a first motor and a second motor. The first motor is connected to the stirring shaft and is used to control the stirring shaft to drive the stirring rod and the U-shaped scraper to rotate. The second motor is connected to the coating kettle and is used to control the rotation of the coating kettle. Under the combined action of the stirring inside the kettle and the rotation of the kettle body itself, the liquid-phase coating agent is evenly coated on the surface of the powder particles as much as possible, the flow degree of the powder increases, and the stirring effect is enhanced.

[0024] Wherein, both the first motor and the second motor are adjustable-speed motors.

[0025] In the present invention, a second discharge port is provided at the bottom of the coating kettle for discharging the negative electrode material from the coating device.

[0026] In the present invention, the first feed port can be located at the central position of the top of the fluidization chamber.

[0027] In the present invention, preferably, the first feed port and the first discharge port are arranged in alignment.

[0028] In some embodiments, a heat insulation layer is provided on the inner wall surface of the fluidization chamber to prevent the coating agent from affecting the coating effect due to an increase in viscosity caused by a decrease in temperature.

[0029] In some embodiments, the coating device includes a connecting pipe. One end of the connecting pipe is connected to the first discharge port, and the other end is connected to the second feed port.

[0030] In some embodiments, the atomizer includes an ultrasonic atomizer, and the liquid-phase coating agent is sprayed into the fluidization chamber in an ultrasonic atomization manner.

[0031] In a specific embodiment, the ultrasonic atomizer includes an ultrasonic atomization element, an atomization chamber, a tapered hole with a wider upper part and a narrower lower part, and a nozzle, which are arranged in sequence from top to bottom. The ultrasonic atomization element is arranged on the liquid inlet pipe.

[0032] In some embodiments, a pressure gauge is provided on the fluidization chamber for monitoring the pressure of the fluidization chamber.

[0033] In some embodiments, an exhaust port is provided at the bottom of the fluidization chamber for adjusting the internal pressure of the fluidization chamber to prevent the internal pressure of the fluidization chamber from being too high.

[0034] In the present invention, a first through hole can be provided on the side wall surface of the lower part of the fluidization chamber for connecting the fluidizer arranged inside the fluidization chamber with an external air supply element.

[0035] Wherein, the fluidization medium in the fluidizer can be selected from different types of fluidization media according to the requirements of the production process.

[0036] In some embodiments, an air inlet is provided on the fluidizer for supplying, through an externally connected air supply element, a gas that fluidizes the material into the interior of the fluidization chamber.

[0037] In some embodiments, the fluidizer includes an inner member having a mesh structure; its outer diameter is slightly smaller than the inner diameter of the fluidization chamber. An inner member with an appropriate aperture ratio can be selected according to process requirements, which can not only promote the uniform distribution of the gas and powder mixture, but also reduce the obstructive effect of the gas and powder.

[0038] In the present utility model, a powder metering tank and a coating agent metering tank are provided to strictly control the coating amount of the powder.

[0039] In the present utility model, a heat tracing element may be provided on the pipeline between the coating agent storage tank and the coating agent metering tank to avoid the influence of too high or too low temperature on the characteristics of the coating agent material.

[0040] In some embodiments, the coating device includes a powder metering tank and a coating agent metering tank for precisely controlling the coating amount of the coating agent on the powder by adjusting the feeding amounts of the powder and the coating agent; the outlet of the powder metering tank is connected to the first feeding port, and the coating agent metering tank is connected to the liquid inlet pipeline. When coating a negative electrode material (such as graphite), it is necessary to accurately weigh the powder and the coating agent, because the amounts of the powder and the coating agent have a great influence on the results of the electrical properties of the final product.

[0041] In the present utility model, a second through hole may be formed on the side wall surface of the upper part of the fluidization chamber for connecting the liquid inlet pipeline provided inside it to the coating agent metering tank.

[0042] In some embodiments, the inlet of the powder metering tank is connected with a negative pressure feeding element for transporting the powder into the powder metering tank; the negative pressure feeding element is used to make the feeding system in a negative pressure state and transport the raw material to the powder metering tank.

[0043] In some embodiments, the inlet of the coating agent metering tank is connected with a coating agent storage tank.

[0044] In a specific embodiment, a heating element is provided on the inner wall of the coating agent metering tank; stirring elements are provided inside both the powder metering tank and the coating agent metering tank.

[0045] In a preferred embodiment, the powder metering tank includes a first stirring paddle, and the first stirring paddle is arranged on the central axis of the powder metering tank to avoid the poor fluidity of the powder, which is likely to cause difficult feeding situations such as bridging.

[0046] In a preferred embodiment, the coating agent metering tank includes a second stirring paddle, which is arranged on the central axis of the coating agent metering tank and is used for continuously dispersing the coating agent to prevent the viscosity at the bottom of the coating agent metering tank from being too high due to sedimentation problems, thereby affecting the quality of the coating agent fed.

[0047] In the present invention, the optimal coating amount can be determined by combining electrical property tests, and the coating amount can be obtained by calculating the residual carbon amount; the residual carbon amount of the graphite negative electrode material is generally within 1-2%, or even within 1%; by using the coating device as described above to coat the graphite negative electrode material, the liquid-phase coating agent can maintain the uniformity and consistency of coating under a relatively low coating amount.

[0048] In the present invention, the above-described coating device is used for coating graphite powder as follows: the powder enters the fluidization chamber from the feeding port at the top, and the powder is made to fall in the central area of the fluidization chamber by adjusting the feeding speed. The coating agent passes through the feeding pipeline and is sprayed out after being atomized by the atomizer. The fluidization medium is sprayed upward from the fluidizer through the air inlet to prevent large particles or agglomerated particles from depositing at the bottom; the fluidization height of the material matches the spraying speed of the fluidization medium, and the fluidization height is lower than the nozzle to avoid affecting the coating effect; after the feeding is completed, since a certain height is reserved between the upper part of the nozzle and the top of the fluidization chamber, the fluidization height can be adjusted by increasing the spraying speed of the fluidization medium to enhance the mixing effect.

[0049] The positive and progressive effects of the present invention are as follows:

[0050] (1) The coating device of the present application adopts a dual mixing method of fluidization and stirring, which overcomes the influence of uneven coating of traditional mechanical mixing on the electrical properties of the final product; improves the coating effect of the negative electrode material and makes the coating of the negative electrode material more uniform.

[0051] (2) The coating device of the present application enables the powder and the liquid-phase coating agent to be mixed in a fluid form, and the treatment process is faster and more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic structural diagram of the graphite negative electrode material coating device in Embodiment 1 of the present invention;

[0053] Figure 2 is a schematic structural diagram of the ultrasonic spraying in the fluidization chamber in Embodiment 1 of the present invention;

[0054] Figure 3 is a schematic structural diagram of the internal components in the fluidizer in Embodiment 1 of the present invention;

[0055] Figure 4 is a schematic structural diagram of the graphite negative electrode material coating device in Comparative Example 1;

[0056] Figure 5 Raman test results of the graphite anode material obtained in Example 1 of the present utility model.

[0057] Figure 6 Raman test results of the graphite anode material obtained in Comparative Example 1.

[0058] Explanation of the reference numerals:

[0059] Powder metering tank 1

[0060] Coating agent metering tank 2

[0061] Pressure gauge 3

[0062] Atomizer 4

[0063] Fluidizer 5

[0064] Air inlet 6

[0065] Exhaust port 7

[0066] First motor 8

[0067] Stirring shaft 9

[0068] Second motor 10

[0069] U-shaped scraper 11

[0070] Coating kettle 12

[0071] Second discharge port 13

[0072] First stirring paddle 14

[0073] Second stirring paddle 15

[0074] Ultrasonic atomization element 16

[0075] Conical hole 17

[0076] Nozzle 18

[0077] Internal component 19

[0078] First feed port 20

[0079] First discharge port 21

[0080] Second feed port 22

[0081] Connecting pipe 23

[0082] Atomization chamber 24

[0083] Liquid inlet pipe 25

[0084] Stirring rod 26. Detailed implementation manners

[0085] The following is a preferred embodiment, which will be described more clearly and completely in combination with the accompanying drawings for the present utility model.

[0086] Embodiment 1

[0087] This embodiment is a coating device for graphite anode materials. Figure 1 It is a schematic structural diagram of the coating device for graphite anode materials in this embodiment. This coating device is used for coating graphite powder with a liquid-phase coating agent, and includes a fluidization unit and a stirring unit that are interconnected; the fluidization unit is arranged above the stirring unit;

[0088] The fluidization unit includes a fluidization chamber, a liquid inlet pipe 25, and a fluidizer 5; the top and bottom of the fluidization chamber are respectively provided with a first feed inlet 20 and a first discharge outlet 21, and the first feed inlet 20 is used for feeding powder; the liquid inlet pipe 25 is arranged radially in the upper part of the fluidization chamber along the radial direction of the fluidization chamber, and the liquid inlet pipe 25 is provided with a plurality of ultrasonic atomizers 4 with openings facing downwards, which are used for atomizing the liquid-phase coating agent and then feeding it into the fluidization chamber; the fluidizer 5 is arranged radially in the lower part of the fluidization chamber along the radial direction of the fluidization chamber, and the fluidizer 5 is provided with a plurality of air outlets facing upwards, which are used for making the mixture of powder and liquid-phase coating agent in a fluidized state; the distance between the liquid inlet pipe 25 and the fluidizer 5 is 1 / 2 of the height of the fluidization chamber.

[0089] The stirring unit includes a coating kettle 12 which is provided with a stirring element and is in a cylindrical shape. The top of the coating kettle 12 is provided with a second feed inlet 22, and the second feed inlet 22 is connected to the first discharge outlet 21, which is used for connecting the fluidization chamber and the coating kettle 12.

[0090] The stirring element is arranged along the axis of the coating kettle 12, and includes a stirring shaft 9, a U-shaped scraper 11, and two parallel stirring rods 26; a hollow connecting part is provided at the central part of each stirring rod 26, and each stirring rod 26 is vertically sleeved on the stirring shaft 9 through the connecting part; the U-shaped scraper 11 is symmetrically connected to both ends of the stirring rod 26; the distance between the U-shaped scraper 11 and the inner wall of the coating kettle 12 is 4 mm. The coating device includes a first motor 8 and a second motor 10 with adjustable speeds. The first motor 8 is connected to the stirring shaft 9 and is used for controlling the stirring shaft 9 to drive the stirring rod 26 and the U-shaped scraper 11 to rotate; the second motor 10 is connected to the coating kettle 12 and is used for controlling the rotation of the coating kettle 12. The bottom of the coating kettle 12 is provided with a second discharge outlet 13.

[0091] The first feed inlet 20 is located at the central position of the top of the fluidization chamber, and it is arranged in alignment with the first discharge outlet 21. The inner wall surface of the fluidization chamber is provided with a heat preservation layer; the fluidization chamber is provided with a pressure gauge 3; the bottom of the fluidization chamber is provided with an exhaust port 7; the fluidizer 5 is provided with an air inlet 6.

[0092] The coating device includes a connecting pipe 23. One end of the connecting pipe 23 is connected to the first discharge port 21, and the other end is connected to the second feed port 22. The coating device includes a powder metering tank 1 and a coating agent metering tank 2 for accurately controlling the coating amount of the coating agent on the powder. The outlet of the powder metering tank 1 is connected to the first feed port 20, and the coating agent metering tank 2 is connected to the liquid inlet pipe 25. A negative pressure feeding element is connected to the inlet of the powder metering tank 1 for transporting the powder into the powder metering tank 1. A coating agent storage tank is connected to the inlet of the coating agent metering tank 2. A heat tracing element is provided on the pipeline between the coating agent storage tank and the coating agent metering tank 2, and a heating element is provided on the inner wall of the coating agent metering tank 2. The powder metering tank 1 includes a first stirring paddle 14 which is arranged on the central axis of the powder metering tank 1. The coating agent metering tank 2 includes a second stirring paddle 15 which is arranged on the central axis of the coating agent metering tank 2.

[0093] Figure 2 It is a schematic structural diagram of the ultrasonic atomizer 4 of this embodiment. The ultrasonic atomizer 4 includes an ultrasonic atomizing element 16, an atomizing chamber 24, a tapered hole 17 with a wider upper part and a narrower lower part, and a nozzle 18 which are arranged in sequence from top to bottom. The ultrasonic atomizing element 16 is arranged on the liquid inlet pipe 25. A high-frequency oscillating current is applied to the ultrasonic atomizer 4 to convert the liquid into ultrasonic mechanical vibration, and the atomization propagation is carried out under the ultrasonic vibration. Under the action of ultrasonic waves, the surface of the liquid molecules is damaged, and the liquid surface escapes to form droplets, thus realizing atomization. The diameter of the droplets can be adjusted according to the ultrasonic vibration energy, and the atomization effect can be adjusted according to the characteristics of different coating agents.

[0094] Figure 3 It is a schematic structural diagram of the internal component 19 in the fluidizer 5 of this embodiment. The internal component 19 of the fluidizer 5 has a net structure, and its outer diameter is slightly smaller than the inner diameter of the fluidization chamber. If it is necessary to coat ultrafine powder, it is easy for the individual particles of the ultrafine powder to adhere to each other, resulting in uneven distribution between the powder and the coating agent. Therefore, the net structure can make the particles be fully fluidized.

[0095] Using the coating device of this embodiment for the coating process, the object to be coated by this coating device is artificial graphite powder, and the coating agent is liquid-phase asphalt. The coating amount is determined by the residual carbon content. Among them, the artificial graphite powder has the following characteristics: particle size D50: 5 - 15 μm, loose bulk density: 0.5 - 0.7 g / cm 3 ³, tapped density: 0.9 - 1.1 g / cm 3 ³. According to the Geldart particle classification, it belongs to Class C particles of ultrafine powder. After coating, the negative electrode material of the lithium-ion battery is obtained.

[0096] Comparative Example 1

[0097] This comparative example is a compaction mixing device for tar liquid phase coating described in the specific implementation manner of CN211800111U, which belongs to a conventional coating device in the field. Figure 4 It is a schematic structural diagram of the graphite negative electrode material coating device of this comparative example.

[0098] Using the coating device of this comparative example for the coating process, the object to be coated by this coating device is artificial graphite powder such as that in Example 1 with graphite. After coating, the negative electrode material of the lithium-ion battery is obtained.

[0099] Effect Example 1

[0100] The negative electrode materials obtained in Example 1 and Comparative Example 1 were subjected to Raman testing. The instrument used for this testing method is the In-Via type laser confocal micro-Raman spectrometer of Renishaw Company in the UK; the test parameters are as follows: the laser wavelength is 532 nm, and the test range is: 1000 - 2000 cm -1 .

[0101] Figure 5 and Figure 6 are respectively the Raman test results of the negative electrode materials obtained in Example 1 and Comparative Example 1. As Figure 5 shown, the I D-P / I G median of the negative electrode material obtained by using the coating device of Example 1 is 0.238; as Figure 6 shown, the I D-P / I G median of the negative electrode material obtained by using the coating device of Comparative Example 1 is 0.309. It can be seen that under the condition of using the same material, when using different coating devices, there are obvious differences in the coating effects; when using the coating device of this application for coating, the I D-P / I G median of the obtained negative electrode material is reduced, the coating uniformity is improved, and the coating effect is improved.

Claims

1. A coating device for graphite negative electrode material, characterized in that: It comprises a fluidizing unit and a stirring unit which are interconnected; the fluidizing unit is arranged above the stirring unit; The fluidizing unit comprises a fluidizing chamber, a liquid inlet pipe and a fluidizer; the top and bottom of the fluidizing chamber are respectively provided with a first feed port and a first discharge port, the first feed port is used for feeding powder; the liquid inlet pipe is arranged at the upper part of the fluidizing chamber along the radial direction of the fluidizing chamber, the liquid inlet pipe is provided with a plurality of atomizers with openings facing downwards, which are used for atomizing the liquid coating agent and then feeding the liquid coating agent into the fluidizing chamber; the fluidizer is arranged at the lower part of the fluidizing chamber along the radial direction of the fluidizing chamber, the fluidizer is provided with a plurality of upward gas outlets, which are used for fluidizing the mixture of the powder and the liquid coating agent; the distance between the liquid inlet pipe and the fluidizer is 1 / 2 to 3 / 5 of the height of the fluidizing chamber; The stirring unit comprises a coating kettle provided with a stirring element, a second feed port is provided on the top of the coating kettle, and the second feed port is connected with the first discharge port for connecting the fluidizing chamber with the coating kettle.

2. The coating device for graphite negative electrode material according to claim 1, characterized in that: The stirring element is arranged along the axis of the coating kettle, and comprises a stirring shaft, a U-shaped scraper and a plurality of stirring rods arranged in parallel; a hollow connecting portion is arranged at the center of each stirring rod, and each stirring rod is vertically sleeved on the stirring shaft through the connecting portion; the U-shaped scraper is symmetrically connected to both ends of the stirring rod; The distance between the U-shaped scraper and the inner wall surface of the coating kettle is 3-5 mm.

3. The coating device for graphite negative electrode material according to claim 2, characterized in that: The number of the stirring rods is 1-3; The coating device includes a first motor and a second motor. The first motor is connected to the stirring shaft and is used to control the stirring shaft to drive the stirring rod and the U-shaped scraper to rotate; the second motor is connected to the coating kettle and is used to control the rotation of the coating kettle.

4. The coating device for graphite negative electrode material according to claim 1, characterized in that: The inner wall surface of the fluidized chamber is provided with a heat-insulating layer; The coating device comprises a connecting pipe, one end of which is connected to the first discharge port, and the other end of which is connected to the second feed port.

5. The coating device for graphite negative electrode material according to claim 1, characterized in that: The nebulizer comprises an ultrasonic nebulizer; The fluidizing chamber is provided with a pressure gauge for monitoring the pressure of the fluidizing chamber; An exhaust port is provided at the bottom of the fluidizing chamber for adjusting the internal pressure of the fluidizing chamber; The fluidizer is provided with an air inlet for supplying gas for fluidizing the material to the interior of the fluidizing chamber through an external air supply element; The fluidizer includes an internal member in a mesh structure.

6. The coating device for graphite negative electrode material according to claim 5, characterized in that: The ultrasonic atomizer comprises an ultrasonic atomizing element, an atomizing chamber, a tapered hole which is wide at the top and narrow at the bottom, and a nozzle which are arranged in sequence from top to bottom; the ultrasonic atomizing element is arranged on the liquid inlet pipe.

7. The coating device for graphite negative electrode material according to claim 1, characterized in that: The coating device comprises a powder metering tank and a coating agent metering tank, which are used to adjust the feed amount of the powder and the coating agent respectively; the outlet of the powder metering tank is connected to the first feed port, and the coating agent metering tank is connected to the liquid inlet pipeline; The inlet of the powder metering tank is connected to a negative pressure feeding element for conveying powder into the powder metering tank.

8. The coating device for graphite negative electrode material according to claim 7, characterized in that: The inner wall of the coating agent metering tank is provided with a heating element; the insides of the powder metering tank and the coating agent metering tank are both provided with stirring elements.

9. The coating device for graphite negative electrode material according to claim 8, characterized in that: The powder measuring tank comprises a first stirring paddle, and the first stirring paddle is arranged on the central axis of the powder measuring tank.

10. The coating device for graphite negative electrode material according to claim 8, characterized in that: The coating agent metering tank comprises a second stirring paddle, and the second stirring paddle is arranged on the central axis of the coating agent metering tank.

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