Lithium battery negative electrode material screening device

Abstract

The invention relates to the technical field of lithium batteries, in particular to a lithium battery negative electrode material screening device which comprises a screening and grinding cylinder capable of rotating around the axis of the screening and grinding cylinder, a first spiral blade and a second spiral blade, a grinding bin and a screening bin are defined in the screening and grinding cylinder through an isolation part, and screening holes are formed in the outer side wall of the screening and grinding cylinder in a penetrating mode; the first spiral blade is arranged on the screening bin, a spiral screening channel is formed between the first spiral blade and the inner wall of the screening bin, and a material inlet is formed in the first end of the screening channel. The spiral blade II is arranged in the grinding bin, and a spiral grinding channel is formed between the spiral blade II and the inner wall of the screening bin; the rotating direction of the grinding channel is opposite to that of the screening channel, the first end of the grinding channel communicates with the second end of the screening channel through a first communicating part, the second end of the grinding channel communicates with the first end of the screening channel through a second communicating part, and the first end and the second end of the grinding channel are provided with a medium inlet and a medium outlet correspondingly. According to the screening device, large-particle graphene can be effectively ground and repeatedly screened in the screening process.

Description

Technical Field

[0001] The invention relates to the technical field of lithium batteries, and in particular to a lithium battery negative electrode material screening device. Background Art

[0002] As a negative electrode material for batteries, graphene shows important value in improving the performance of lithium-ion batteries due to its ultra-large specific surface area, excellent electrical and thermal conductivity, and micro-nanoscale. During the preparation process, in order to obtain uniform electrode materials, graphene particles must be accurately screened according to their diameter size.

[0003] At present, companies are facing some efficiency and operational challenges when screening graphene particles. The combination of vibrating screen and filter cannot screen out graphene of a specific diameter in one go, and the screening process usually needs to be repeated. In addition, due to the viscosity of graphene, it is easy to adhere to the filter during the filtration process, causing blockage and affecting the screening efficiency. The manual method of adding graphene in batches not only reduces work efficiency, but also makes it difficult to control the amount of material added each time, which poses an obstacle to the realization of an efficient and continuous screening process.

[0004] In response to the above problems, the invention patent (publication number CN114602786B) proposed a lithium battery negative electrode material screening device. The device realizes one-time filtration of graphene particles of different diameters by setting through holes and guide blocks with different diameters and utilizing the movement of graphene particles when the screening box rotates. This design not only avoids secondary screening and reduces workload, but also significantly improves screening efficiency.

[0005] Nevertheless, some defects are still found in the above-mentioned lithium battery negative electrode material screening device in practical applications. For example, during the screening process, larger graphene particles may not be able to pass through the through holes and remain in the screening box. These particles are difficult to take out, and even if they are taken out, they need to be ground before they can be screened again, which undoubtedly adds additional steps and complexity. For this reason, the present invention proposes a lithium battery negative electrode material screening device with integrated grinding and screening functions. Summary of the invention

[0006] The object of the present invention is to provide a lithium battery negative electrode material screening device for solving the problems raised in the above-mentioned background technology.

[0007] The present invention is achieved through the following technical solutions:

[0008] A lithium battery negative electrode material screening device comprises a screening cylinder rotatable around its own axis, a spiral blade 1 and a spiral blade 2, wherein a grinding bin and a screening bin arranged around the grinding bin are defined by an isolation portion in the screening cylinder, and screening holes are provided through the outer wall of the screening cylinder; the spiral blade 1 is arranged in the screening bin and forms a spiral screening channel with the inner wall of the screening bin, and a material inlet is provided at the first end of the screening channel; the spiral blade 2 is arranged in the grinding bin and forms a spiral grinding channel with the inner wall of the screening bin; the grinding channel and the screening channel have opposite rotation directions, the first end of the grinding channel is connected to the second end of the screening channel through a connecting portion 1, the second end of the grinding channel is connected to the first end of the screening channel through a connecting portion 2, and the first end and the second end of the grinding channel are respectively provided with a medium inlet and a medium outlet for the grinding medium to pass through.

[0009] Optionally, the screening device also includes an outer cylinder, the screening cylinder is rotatably arranged in the upper part of the outer cylinder, the lower part of the outer cylinder is provided with an installation opening, and the installation opening is inserted with a finished product collection trough that can extend into the lower part of the outer cylinder.

[0010] Optionally, a driving motor is installed on the outer cylinder body to drive the screening cylinder to rotate around its own axis.

[0011] Optionally, the material inlet is arranged on the end face of the first end of the screening bin, and the screening device also includes a feeding hopper, which is relatively fixed to the axis of the screening cylinder, and the discharge end of the feeding hopper is in contact with the end face of the first end of the screening cylinder and is on the rotation trajectory of the material inlet.

[0012] Optionally, the medium outlet is arranged at a position on the end face of the first end of the screening bin close to the edge of the screening bin, an external discharge port allowing the grinding medium to pass is provided at a position on the outer cylinder corresponding to the rotation trajectory of the medium outlet, and a grinding medium collector is provided at a position outside the outer cylinder corresponding to the external discharge port.

[0013] Optionally, the screening device also includes a grinding medium additive, which includes an additive body and a propeller, the additive body having a propulsion channel and an addition channel arranged at an angle, the first end of the propulsion channel being open and rotatably connected to the medium inlet, the first end of the addition channel being connected to the middle of the propulsion channel, and the second end of the addition channel being open; the propeller is disposed at the second end of the propulsion channel and can be telescopic or reciprocatingly moved along the length direction of the propulsion channel.

[0014] Optionally, the propeller is a cylinder, a hydraulic cylinder or an electric push rod installed at the second end of the propulsion channel.

[0015] Optionally, a limiting structure is provided on the adder body at the position where the adding channel and the advancing channel are connected, and the limiting structure is configured to increase the resistance of the grinding medium to movement along the advancing channel.

[0016] Optionally, the limiting structure is a limiting groove that is recessed on the additive body.

[0017] Optionally, the screening channel is a closed structure.

[0018] Compared with the prior art, the present invention provides a lithium battery negative electrode material screening device, which has the following beneficial effects:

[0019] 1. The present invention realizes the function of effectively grinding and repeatedly screening larger particles of graphene during the screening process by providing a grinding chamber and a screening chamber composed of a screening cylinder, a spiral blade 1, a spiral blade 2 and a separation part, thereby solving the problem that it is difficult to remove and process materials with oversized particles in traditional screening devices. This not only reduces additional processes and operational complexity, but also improves screening efficiency and material utilization, thereby optimizing the preparation process of lithium battery negative electrode materials; at the same time, the screening device utilizes the vibration generated by the movement of the grinding medium in the grinding channel to improve the screening efficiency, ensure that all materials meet the specified particle size requirements, thereby improving the preparation quality and efficiency of lithium battery negative electrode materials;

[0020] 2. The present invention realizes the function of continuously adding steel balls into the grinding chamber by providing a grinding medium adder including an adder body and a propeller arranged at an angle. This structure solves the problem that the grinding medium cannot be automatically replenished in the traditional screening device, and ensures the grinding efficiency and the stability of the grinding effect;

[0021] 3. The present invention realizes the automatic discharge and collection of steel balls in the grinding bin by arranging the medium outlet at a position close to the edge of the first end face of the screening bin, in cooperation with the external discharge port on the outer cylinder and the external grinding medium collector. This structure solves the cumbersome problem of manually cleaning the steel balls in the grinding bin in the traditional device, reduces downtime, and improves the automation level and work efficiency of the screening device. At the same time, this design also optimizes the operation process, avoids the possible risks when manually collecting grinding media, and ensures the safety of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0023] Figure 2 A schematic diagram showing the structure of the interior of the outer cylinder of the present invention;

[0024] Figure 3 It is a schematic diagram of the top view of the structure of the present invention;

[0025] Figure 4 For the present invention Figure 3 Schematic diagram of the cross-section structure at AA;

[0026] Figure 5 For the present invention Figure 4 A schematic diagram of the enlarged structure at B;

[0027] Figure 6 For the present invention Figure 3 Schematic diagram of the projection structure;

[0028] Figure 7 For the present invention Figure 6 Enlarged structural diagram at C.

[0029] In the figure: 1. Screening cylinder; 2. Isolation part; 3. Grinding chamber; 4. Screening chamber; 5. Screening hole; 6. Spiral blade 1; 7. Screening channel; 8. Material inlet; 9. Spiral blade 2; 10. Grinding channel; 11. Connecting part 1; 12. Connecting part 2; 13. Medium inlet; 14. Medium outlet; 15. Outer cylinder; 16. Mounting port; 17. Finished product collecting tank; 18. Driving motor; 19. Feeding hopper; 20. External discharge port; 21. Grinding medium collector; 22. Feeder body; 23. Propeller; 24. Propelling channel; 25. Adding channel; 26. Limiting groove; 27. Steel ball. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example: See Figures 1 to 7, according to an embodiment of the present invention, a technical solution is provided: a lithium battery negative electrode material screening device, comprising a screening cylinder 1 rotatable around its own axis, a spiral blade 1 6 and a spiral blade 2 9, wherein a grinding bin 3 and a screening bin 4 arranged around the grinding bin 3 are defined by an isolation portion 2 in the screening cylinder 1, and a screening hole 5 is provided through the outer wall of the screening cylinder 1. It can be understood that the screening hole 5 should only allow materials of a specified particle size to pass through; the spiral blade 1 6 is provided in the screening bin 4 and forms a spiral screening channel 7 with the inner wall of the screening bin 4, and a material inlet 8 is provided at the first end of the screening channel 7; the spiral blade 2 9 is provided in the grinding bin 4 and the inner wall of the screening bin 4 forms a spiral screening channel 7, and a material inlet 8 is provided at the first end of the screening channel 7; the spiral blade 2 9 is provided in the grinding bin 4 and the inner wall of the screening bin 4 forms a spiral screening channel 7 with the inner wall of the screening bin 4 ... A spiral grinding channel 10 is formed between the bin 3 and the inner wall of the screening bin 4. In order to ensure that the material can be continuously and fully screened during the movement in the grinding channel 10, a screening hole 5 covering the entire grinding channel 10 can be provided on the outer wall of the screening cylinder 1; the grinding channel 10 and the screening channel 7 have opposite rotation directions, the first end of the grinding channel 10 is connected to the second end of the screening channel 7 through a connecting portion 11, and the second end of the grinding channel 10 is connected to the first end of the screening channel 7 through a connecting portion 2 12, and the first end and the second end of the grinding channel 10 are respectively provided with a medium inlet 13 and a medium outlet 14 for the grinding medium to pass through. When the above scheme is implemented, the material (such as graphene used as a negative electrode material for lithium batteries) is added to the first end of the screening channel 7 from the material inlet 8. As the screening cylinder 1 rotates, the material moves toward the second end of the screening channel 7. During the movement, the material that meets the particle size requirements leaks out from the screening hole 5, and the material with too large a particle size continues to move along the screening channel 7. When reaching the second end of the screening channel 7, the material that has not been screened out enters the first end of the grinding channel 10 through the connecting portion 11. At this time, the grinding medium (such as Steel balls 27), since the grinding channel 10 and the screening channel 7 have opposite rotation directions, as the screening cylinder 1 continues to rotate, the steel balls 27 and the grinding media are mixed and move toward the second end of the grinding channel 10 together. In this process, the moving steel balls 27 can not only grind the materials in the grinding channel 10, but also make the screening cylinder 1 produce effective vibrations, thereby improving the screening efficiency of the materials in the screening channel 7. Finally, the ground materials fall back to the first end of the screening channel 7 through the connecting portion 12 and continue to be screened, and this is repeated until all the materials meet the specified particle size requirements and are screened out. Therefore, when using the screening device to screen materials, there is no need to remove the materials that cannot be discharged by the screening hole 5 due to excessive particle size. Instead, these materials with excessive particle size are repeatedly ground and screened until all the materials meet the particle size requirements. At the same time, the vibration generated by the movement of the steel balls 27 during the grinding process is used to accelerate the screening of the materials and improve the screening efficiency of the materials.

[0032] In this example, the connecting portion 1 1 and the connecting portion 2 12 are both hole structures. In other embodiments, the connecting portion 1 1 and the connecting portion 2 12 may also be solid structures, such as pipes.

[0033] In this exemplary embodiment, the screening device further includes an outer cylinder 15, the screening cylinder 1 is rotatably arranged in the upper part of the outer cylinder 15, and the lower part of the outer cylinder 15 is provided with a mounting port 16, and the mounting port 16 is inserted with a finished product collection tank 17 which can be inserted into the lower part of the outer cylinder 15. The screening cylinder 1 is covered by the outer cylinder 15 to create a relatively closed screening space, which can effectively reduce dust during the screening process; in addition, the finished product collection tank 17 can collect finished products that fall from the screening holes 5 of the screening cylinder 1, and the finished product collection tank 17 can be pulled out from the mounting port 16, that is, these finished products can be easily taken out from the inner part of the outer cylinder 15.

[0034] In order to realize the rotational movement of the sieve-grinding cylinder 1 around its own axis, in this exemplary embodiment, a driving motor 18 for driving the sieve-grinding cylinder 1 to rotate around its own axis is installed on the outer cylinder 15. When the driving motor 18 is started, the sieve-grinding cylinder 1 is driven to rotate around its own axis. Of course, as long as the sieve-grinding cylinder 1 can be made to rotate around its own axis, there is no particular limitation on the specific driving method of the sieve-grinding cylinder 1.

[0035] In order to realize automatic addition of materials into the screening bin 4 through the material inlet 8, in this exemplary embodiment, the material inlet 8 is arranged on the end face of the first end of the screening bin 4, and the screening device also includes a hopper 19, which is roughly funnel-shaped, with the upper end of the hopper 19 being a feed end with a larger opening, and the lower end being a discharge end with a smaller opening; the hopper 19 is relatively fixed to the axis of the screening cylinder 1, and preferably, the hopper 19 can be fixedly installed on the outer cylinder 15; the discharge end of the hopper 19 is in contact with the end face of the first end of the screening cylinder 1 And it is on the rotation trajectory of the material inlet 8, that is to say, with the rotation of the screening cylinder 1, the discharge end of the feeding hopper 19 will at least partially overlap with the material inlet 8, when the discharge end of the feeding hopper 19 partially or completely overlaps with the material inlet 8, a small amount of material in the feeding hopper 19 will enter the screening bin 4 through the overlapping part of the two, and with the continued rotation of the screening cylinder 1, the discharge end of the feeding hopper 19 will be blocked again until it overlaps with the material inlet 8 again. In this way, the purpose of continuous and automatic feeding into the screening bin 4 can be achieved.

[0036] The steel ball 27 is a common grinding medium. In this exemplary embodiment, taking the grinding medium as the steel ball 27 as an example, in order to realize the automatic discharge of the steel ball 27 in the grinding chamber 3, the medium outlet 14 is arranged at the end surface of the first end of the screening chamber 4 near the edge of the screening chamber 4, and the outer discharge port 20 that allows the grinding medium to pass is arranged at the position corresponding to the rotation track of the medium outlet 14 on the outer cylinder 15, and a grinding medium collector 21 is arranged at the position corresponding to the outer discharge port 20 outside the outer cylinder 15. Since the width of the second end of the grinding channel 10 will gradually decrease, when the steel ball 27 in the grinding chamber 3 moves to the second end of the grinding channel 10, the steel ball 27 will enter the medium outlet 14 under the push of the spiral blade 29, and when the medium outlet 14 coincides with the outer discharge port 20, the steel ball 27 will be discharged through the outer discharge port 20, and the discharged steel ball 27 will fall into the grinding medium collector 21 and be uniformly collected, thereby realizing the automatic discharge and collection of the steel ball 27 in the grinding chamber 3.

[0037] In order to facilitate the continuous addition of grinding media into the grinding bin 3, in this exemplary embodiment, taking the grinding media as steel balls 27 as an example, the screening device also includes a grinding media adder, the grinding media adder includes an adder body 22 and a propeller 23, the adder body 22 has a propulsion channel 24 and a adding channel 25 arranged at an angle, in this example, the angle between the propulsion channel 24 and the adding channel 25 is 90°, the first end of the propulsion channel 24 is open and rotatably connected to the medium inlet 13, the first end of the propulsion channel 24 and the medium inlet 13 can be rotatably connected in a clearance fit or by a bearing connection, the first end of the adding channel 25 is connected to the middle of the propulsion channel 24, and the second end of the adding channel 25 is open; the propeller 23 is provided at the second end of the propulsion channel 24 and can be telescopic or reciprocating along the length direction of the propulsion channel 24, it can be understood that the middle of the propulsion channel 24 is not a specific position, as long as it is between the propeller 23 and the first end of the adding channel 25 can be called the middle of the propulsion channel 24. In specific implementation, multiple steel balls 27 can be stored in the adding channel 25, and the propeller 23 is used to push the steel balls 27 into the grinding chamber 3 one at a time by telescoping or reciprocating in the pushing channel, thereby achieving the purpose of continuously adding steel balls 27 to the grinding chamber 3.

[0038] As a preferred embodiment, in this exemplary embodiment, the propeller 23 is a cylinder or a hydraulic cylinder or an electric push rod installed at the second end of the propulsion channel 24. In specific implementation, the action of the propeller 23 can be controlled by the controller to make the propeller 23 extend and retract, thereby realizing the continuous and automatic addition of grinding media into the grinding chamber 3. Of course, as long as the automatic and continuous addition of grinding media into the grinding chamber 3 can be realized, there is no particular limitation on the specific structural form of the propeller 23.

[0039] Generally speaking, steel balls 27 are used as grinding media. Due to the external shape, when the propeller 23 is not in motion, the steel balls 27 are also easy to roll along the propulsion channel 24 into the grinding chamber 3, resulting in inaccurate control of the addition of the steel balls 27. In order to more accurately control the addition of the steel balls 27, in this exemplary embodiment, a limiting structure is provided on the adding body 22 at the connecting position of the adding channel 25 and the propulsion channel 24, and the limiting structure is configured to increase the resistance of the grinding media to move along the propulsion channel 24. In this way, the steel balls 27 at the bottom of the adding channel 25 can be stabilized at the connecting position of the adding channel 25 and the propulsion channel 24, and only when the propeller 23 applies a certain thrust to the steel balls 27 at this position, the steel balls 27 will be pushed into the grinding chamber 3, thereby achieving accurate control of the steel balls 27 added to the grinding chamber 3.

[0040] As a preferred embodiment, the limiting structure is a limiting groove 26 that is concavely arranged on the adding device body 22. The limiting groove 26 has a certain limiting effect on the movement of the steel ball 27 along the length direction of the propulsion channel 24, that is, it can increase the resistance of the steel ball 27 to move along the propulsion channel 24, so that the steel ball 27 at the connecting position of the adding channel 25 and the propulsion channel 24 will not roll into the grinding chamber 3 uncontrollably, thereby ensuring the control of the adding steel ball 27. Of course, in other embodiments, the limiting structure can also be a magnet arranged at the connecting position of the adding channel 25 and the propulsion channel 24, and the steel ball 27 is attracted by the magnetic force of the magnet, so that the steel ball 27 can be stabilized at the connecting position of the adding channel 25 and the propulsion channel 24 when it is not subjected to the thrust of the propeller 23. Of course, as long as the resistance of the steel ball 27 to move along the propulsion channel 24 can be increased, there is no special restriction on the specific form of the limiting structure.

[0041] In the present exemplary embodiment, the screening channel 7 is a closed structure. It can be understood that the screening channel 7 is a closed structure, which means that the screening channel 7 is closed all around, that is, the outer side and inner side of the spiral blade 6 forming the screening channel 7 are respectively tightly fitted with the inner wall of the screening cylinder 1 and the outer wall of the isolation part 2. The closed screening channel 7 can prevent the material from directly passing through the gap between the inner side of the grinding spiral blade and the isolation part 2, so that the material can only move along the screening channel 7, ensuring the stability of the material movement trajectory, thereby improving the material screening effect.

[0042] Working principle: First, the driving motor 18 is powered on, and the driving motor 18 drives the screening cylinder 1 to rotate. Then, an appropriate amount of material (such as graphene) is added to the feeding hopper 19. The material is first added to the first end of the screening channel 7 through the material inlet 8. As the screening cylinder 1 rotates, the material gradually moves toward the second end of the screening channel 7. In this process, the material that meets the particle size requirements will leak from the screening hole 5 to the finished product collection tank 17, while those materials with too large particles will continue to move along the screening channel 7. When these oversized materials reach the second end of the screening channel 7, they will enter the first end of the grinding channel 10 through the connecting part 11. At this time, the grinding medium adder can be continuously and automatically added to the first end of the grinding channel 10. Grinding media, such as steel balls 27, are added dynamically. Since the grinding channel 10 and the screening channel 7 rotate in opposite directions, as the screening cylinder 1 continues to rotate, the steel balls 27 and the materials are mixed and move toward the second end of the grinding channel 10 together. In this process, the moving steel balls 27 can not only grind the materials in the grinding channel 10, but also make the screening cylinder 1 vibrate effectively, thereby improving the screening efficiency of the materials in the screening channel 7. The ground materials will then fall back to the first end of the screening channel 7 through the connecting portion 12 and be screened again, while the steel balls 27 will be discharged to the grinding medium collector 21 through the medium outlet 14 and the discharge outlet. This process will be repeated until all the materials reach the specified particle size requirements and are screened out. Therefore, when using the screening device to screen materials, there is no need to remove materials that cannot be discharged by the screening hole 5 due to excessive particle size. Instead, these materials with excessively large particle sizes are repeatedly ground and screened until all materials meet the particle size requirements. At the same time, the vibration generated by the movement of the steel ball 27 during the grinding process is used to accelerate the screening of the material and improve the screening efficiency of the material.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lithium battery negative electrode material screening device, characterized in that: include: A sieving and grinding cylinder (1) rotatable about its own axis, wherein a grinding chamber (3) and a sieving chamber (4) arranged around the grinding chamber (3) are defined by an isolation portion (2), and a sieving hole (5) is provided through the outer wall of the sieving and grinding cylinder (1); A spiral blade (6) is disposed in the screening bin (4) and forms a spiral screening channel (7) with the inner wall of the screening bin (4), wherein a material inlet (8) is disposed at a first end of the screening channel (7); and spiral blade 2 (9), which is arranged in the grinding chamber (3) and forms a spiral grinding channel (10) with the inner wall of the screening chamber (4); the grinding channel (10) and the screening channel (7) have opposite rotation directions, the first end of the grinding channel (10) is connected to the second end of the screening channel (7) through a connecting portion 1 (11), the second end of the grinding channel (10) is connected to the first end of the screening channel (7) through a connecting portion 2 (12), and the first end and the second end of the grinding channel (10) are respectively provided with a medium inlet (13) and a medium outlet (14) for the grinding medium to pass through.

2. A lithium battery negative electrode material screening device according to claim 1, characterized in that: The screening device further comprises an outer cylinder (15), the screening cylinder (1) being rotatably arranged at the upper portion of the outer cylinder (15), a mounting opening (16) being provided through the lower portion of the outer cylinder (15), and a finished product collecting trough (17) being inserted into the mounting opening (16) and being extendable into the lower portion of the outer cylinder (15).

3. A lithium battery negative electrode material screening device according to claim 2, characterized in that: The outer cylinder (15) is provided with a driving motor (18) for driving the screening cylinder (1) to rotate around its own axis.

4. A lithium battery negative electrode material screening device according to claim 1 or 2, characterized in that: The material inlet (8) is arranged on the end face of the first end of the screening bin (4), and the screening device also includes a feeding hopper (19), the feeding hopper (19) is relatively fixed to the axis of the screening cylinder (1), and the discharge end of the feeding hopper (19) is in contact with the end face of the first end of the screening cylinder (1) and is located on the rotation trajectory of the material inlet (8).

5. A lithium battery negative electrode material screening device according to claim 2, characterized in that: The medium outlet (14) is arranged at a position on the end surface of the first end of the screening bin (4) close to the edge of the screening bin (4); an external discharge port (20) for allowing the grinding medium to pass is arranged on the outer cylinder (15) at a position corresponding to the rotation trajectory of the medium outlet (14); and a grinding medium collector (21) is arranged at a position outside the outer cylinder (15) corresponding to the external discharge port (20).

6. A lithium battery negative electrode material screening device according to claim 1, 2, 3 or 5, characterized in that: The screening device further comprises a grinding medium additive, the grinding medium additive comprising an additive body (22) and a propeller (23), the additive body (22) having a propulsion channel (24) and a adding channel (25) arranged at an angle, the first end of the propulsion channel (24) being open and rotatably connected to the medium inlet (13), the first end of the adding channel (25) being connected to the middle of the propulsion channel (24), and the second end of the adding channel (25) being open; the propeller (23) being arranged at the second end of the propulsion channel (24) and being telescopic or reciprocating along the length direction of the propulsion channel (24).

7. A lithium battery negative electrode material screening device according to claim 6, characterized in that: The propeller (23) is a cylinder, a hydraulic cylinder or an electric push rod installed at the second end of the propulsion channel (24).

8. A lithium battery negative electrode material screening device according to claim 6, characterized in that: A limiting structure is provided on the adder body (22) at the position where the adding channel (25) and the advancing channel (24) are connected, and the limiting structure is configured to increase the resistance of the grinding medium to movement along the advancing channel (24).

9. A lithium battery negative electrode material screening device according to claim 8, characterized in that: The limiting structure is a limiting groove (26) which is concavely arranged on the adding device body (22).

10. A lithium battery negative electrode material screening device according to claim 1, characterized in that: The screening channel (7) is a closed structure.

Images