A device for intercepting fiber foreign matter in lithium battery graphite powder

Abstract

The application relates to the technical field of lithium battery manufacturing, and particularly discloses a device for intercepting fiber foreign matters in lithium battery graphite powder, which comprises a shell, a rolling brush, a rotating disc and a driving device, a feeding pipe is arranged at the top of the shell, a discharging pipe is arranged at the bottom of the shell, the driving device is arranged in the shell, a plurality of rolling brushes are rotatably arranged on the rotating disc, the roller shafts of the rolling brushes are fixedly provided with planetary gears, and the planetary gears are in meshing transmission connection with a fixed gear ring; the rolling brushes are in contact with the graphite powder through rotation, fiber foreign matters in the graphite powder are intercepted in the form of winding with the bristles, and the filtering efficiency is high in comparison with the existing technology which adopts a vibrating screen; the rolling brushes rotate around the rotating disc while rotating by themselves, the bristles are beneficial to multiple contact with the falling graphite powder, and the interception rate of the fiber foreign matters in the graphite powder is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery manufacturing technology, and in particular to a device for intercepting fibrous foreign matter in graphite powder for lithium batteries. Background Technology

[0002] The negative electrode of a lithium battery is usually made by uniformly coating a mixture of graphite, conductive agent, binder and other additives onto a current collector (metal sheet). When the battery is charged, lithium compounds in the positive electrode ionize into lithium ions and enter the carbon layer of the negative electrode, thereby achieving the purpose of storing energy.

[0003] In actual production, the negative electrode powder used for negative electrode coating may develop bumps or depressions due to the presence of fibrous foreign matter. The sources of these fibrous foreign matter are complex and diverse, including wear and tear on clothing and hair. Judging from the production process, this is mainly because the raw material graphite is often transported in ton bags or individual packages. During the feeding process, fibers from the packaging bags break and mix into the graphite raw material. Some of these fine fibers are difficult to remove. When the negative electrode material is coated, the fibers occupy the positions of the negative electrode powder. If the fibers are encased in the negative electrode powder layer, bumps will occur. If the fibers are relatively coarse, they may peel off, forming depressions. Defects in the negative electrode powder layer can hinder lithium-ion insertion during charging and discharging, making it easier for lithium ions to form metallic lithium at the defective negative electrode sites, i.e., lithium plating. When lithium plating becomes severe, lithium metal dendrites may pierce the separator, causing a short circuit between the positive and negative electrodes, resulting in a fire or explosion of the lithium battery.

[0004] Therefore, it is crucial to ensure the uniformity of the negative electrode powder in the negative electrode coating and to control the amount of residual fibrous foreign matter introduced into the graphite raw material. In the existing technology, multi-stage vibrating screens are usually used to separate fibrous foreign matter in the graphite raw material. However, if the screen mesh is too fine, the screening efficiency is low, which affects the production efficiency. If the screen mesh is too large, short fibrous foreign matter will also be screened off the screen mesh under long-term vibration, making it difficult to effectively intercept and remove the residual fibrous foreign matter in the graphite raw material. Summary of the Invention

[0005] The purpose of this invention is to provide a device for intercepting fibrous foreign matter in graphite powder for lithium batteries, so as to solve the problems existing in the prior art.

[0006] This invention is implemented by the following technical solution: a fiber foreign object interception device in lithium battery graphite powder, comprising a shell, roller brushes, a turntable, and a drive device. A feed pipe is provided at the top of the shell, and a discharge pipe is provided at the bottom of the shell. The drive device is installed inside the shell, comprising a fixed gear ring, planetary gears, a drive shaft, a reducer, and a drive motor. The fixed gear ring is fixedly installed inside the shell. The drive shaft passes through the shell and is coaxially arranged with the fixed gear ring. One end of the drive shaft is connected to the output shaft of the reducer, and the other end is fixedly connected to the turntable. The input shaft of the reducer is connected to the output shaft of the drive motor. The reducer is fixedly installed on the outside of the shell. Several roller brushes are rotatably mounted on the turntable. Planetary gears are fixedly installed on the roller brush shafts passing through the turntable, and the planetary gears mesh with the fixed gear ring for transmission.

[0007] Furthermore, the roller brush includes a brush roller, a roller shaft, and brush bristles. The brush roller is a hollow cylinder, and a roller shaft is coaxially fixedly mounted on the brush roller. The roller shaft is rotatably connected to the turntable through a bearing seat, and several rows of brush bristles are arranged circumferentially on the outer wall of the brush roller.

[0008] Furthermore, a keyway is provided inside the brush roller, and key teeth that engage with the keyway are integrally formed on the roller shaft. A collar is integrally formed on the roller shaft, one end of the brush roller abuts against the collar, and the other end of the brush roller abuts against a fixing screw, which is threadedly connected to the roller shaft.

[0009] Furthermore, the distance between the tips of the bristles of two adjacent roller brushes is 5-10 mm.

[0010] Furthermore, each cluster of bristles comprises 20-50 stainless steel wires with a diameter of 0.2-0.4 mm.

[0011] Furthermore, the length of the bristles protruding from the brush roller is 0.5-0.8 times the diameter of the brush roller.

[0012] Furthermore, it also includes a negative pressure cleaning device, which includes an air inlet pipe and a fixed roller brush. The drive shaft of the drive device is a hollow structure, and an air inlet pipe is coaxially inserted inside the drive shaft. One end of the air inlet pipe is located outside the housing and connected to a high-pressure air source. The other end of the air inlet pipe is located inside the housing, passing through the drive shaft and the turntable and being fixedly connected to the fixed roller brush. Brush bristles are installed on the fixed roller brush, which is a hollow structure. The hollow inner cavity of the fixed roller brush is connected to the air inlet pipe, and several through holes communicating with the hollow inner cavity are opened on the outer wall of the fixed roller brush. The feed pipe of the housing is connected to the first valve, and the discharge pipe is connected to the second valve. A cleaning pipe is provided on the side wall of the housing and is connected to the third valve. The third valve is connected to the dust collector through a pipeline.

[0013] Furthermore, it also includes an inspection port, which is provided on one side of the outer casing. The inspection port is equipped with a movable sealing door on the sealing cover, and the movable sealing door is hinged to the outer casing.

[0014] Advantages of this invention:

[0015] 1. By rotating the roller brush and contacting the graphite powder, the fibrous foreign matter in the graphite powder is intercepted by entanglement with the brush bristles. The graphite powder falls into the shell by gravity. Compared with the existing technology that uses a vibrating screen, the filtration efficiency is high. The resistance of the graphite powder flowing through the roller brush is small and the flow rate is not affected.

[0016] 2. The roller brush rotates around the turntable while also rotating on its own axis, which facilitates multiple contacts between the brush bristles and the falling graphite powder, thereby improving the retention rate of fibrous foreign matter in the graphite powder. The treated fibrous foreign matter can be effectively intercepted.

[0017] 3. By using the brush bristles to entangle with the fibrous foreign objects, the method effectively intercepts shorter fibrous foreign objects, solving the problem of shorter fibrous foreign objects leaking through the screen when the vibrating screen is repeatedly sieved. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention.

[0019] Figure 2 This is a partial structural cross-sectional view of the driving device in Embodiment 1 of the present invention.

[0020] Figure 3 This is an exploded view of the structure of the roller brush in Embodiment 1 of the present invention.

[0021] Figure 4 This is a schematic diagram of the overall structure of Embodiment 4 of the present invention.

[0022] Figure 5 This is an exploded view of the negative pressure cleaning device in Embodiment 4 of the present invention.

[0023] In the diagram: 1. Outer shell; 2. Roller brush; 3. Turntable; 4. Drive unit; 5. Negative pressure cleaning device; 6. First valve; 7. Second valve; 8. Third valve; 9. Inspection port; 10. Movable sealing door; 201. Brush roller; 202. Roller shaft; 203. Brush bristles; 204. Keyway; 205. Key tooth; 206. Shaft collar; 207. Fixing screw; 401. Fixing gear ring; 402. Planetary gear; 403. Drive shaft; 404. Reducer; 405. Drive motor; 501. Air inlet pipe; 502. Fixed roller brush; 503. Through hole. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Example 1: As Figure 1 As shown, this invention provides a fiber foreign object interception device for lithium battery graphite powder, comprising a housing 1, a roller brush 2, a turntable 3, a drive device 4, and an inspection port 9. A feed pipe 101 is provided at the top of the housing 1, and a discharge pipe 102 is provided at the bottom of the housing 1. Graphite powder falls into the housing 1 from the feed pipe 101 and is discharged from the discharge pipe 102. An inspection port 9 is provided on one side of the housing 1, and a movable sealing door 10 is provided at the inspection port 9. The movable sealing door 10 is hinged to the housing 1 by a hinge. During normal operation, the movable sealing door 10 is sealed to the housing 1. When maintenance of the internal mechanism of the housing 1 is required, it can be performed through the inspection port 9.

[0027] like Figure 2 , Figure 3As shown: A drive device 4 is installed inside the outer casing 1. The drive device 4 includes a fixed gear ring 401, a planetary gear 402, a drive shaft 403, a reducer 404, and a drive motor 405. The reducer 404 is fixedly installed on the outside of the outer casing 1, and the fixed gear ring 401 is fixedly installed inside the outer casing 1. The drive shaft 403 passes through the outer casing 1 and is coaxially arranged with the fixed gear ring 401. One end of the drive shaft 403 is connected to the output shaft of the reducer 404, and the other end of the drive shaft 403 is fixedly connected to the turntable 3. The input shaft of the reducer 404 is connected to the output shaft of the drive motor 405. The drive motor 405 drives the turntable 3 to rotate through the reducer 404. Several roller brushes 2 are rotatably installed on the turntable 3. Each roller brush 2 includes a brush roller 201, a roller shaft 202, and brush bristles 203. The brush roller 201 is a hollow cylinder, and the roller shaft 202 is coaxially fixedly inserted through the brush roller 201. Several brushes are arranged circumferentially on the outer wall of the brush roller 201. The dry brush 203, roller shaft 202 and turntable 3 are rotatably connected by bearing seats. The roller shaft 202 of the roller brush 2 passes through the turntable 3 and is fixedly installed with planetary gear 402. The planetary gear 402 is meshed with the fixed gear ring 401 for transmission. When the turntable 3 rotates, the turntable 3 drives the roller shaft 202 of the roller brush 2 to rotate around the fixed gear ring 401. The fixed gear ring 401 is fixed to the outer shell 1 and will not rotate. On the contrary, the planetary gear 402 meshing with the fixed gear ring 401 rotates, thereby driving the roller shaft 202 to rotate. Therefore, the drive device 4 can drive the roller brush 2 on the turntable 3 to rotate around the drive shaft 403. At the same time, the roller brush 2 on the turntable 3 rotates around the roller shaft 202. The roller brush 2 is provided with several rows of bristles 203. Through the contact and collision of the bristles 203 with the falling graphite powder, the rotating roller brush 2 uses the fibrous foreign matter in the material to wrap around the bristles 203, thereby playing the role of removing fibrous foreign matter in the material.

[0028] The distance between the ends of the bristles 203 of two adjacent roller brushes 2 is 5-10mm, ensuring that the two adjacent roller brushes 2 do not collide during rotation while still making full contact with the falling material to prevent material leakage. The brush roller 201 of the roller brush 2 is made of plastic, and 10 rows of blind holes for fixing the bristles 203 are circumferentially opened on the surface of the brush roller 201. The bristles 203 are filled into the blind holes by a bristle implantation machine. Each cluster of bristles 203 includes 20 stainless steel wires with a diameter of 0.4mm. The length of the bristles 203 protruding from the brush roller 201 is 0.8 times the diameter of the brush roller 201. The longer the bristles 203 are, the more the stainless steel wires collide with the material. The more easily the brush bristles bend, the better their flexibility, and the easier it is for fibrous foreign objects to get tangled between the two stainless steel wires. However, the longer the bristles 203 are, the shorter their lifespan, and the more prone they are to plastic deformation, causing the bristles 203 to bend. This increases the gap between the bristles 203 of two adjacent roller brushes 2, resulting in material leakage. Since the fibrous foreign objects in graphite powder are usually several millimeters to tens of millimeters in length, they are very easy to get tangled with or stuck between the two stainless steel wires while rotating. Graphite powder is a particulate matter and does not easily remain on the bristles 203. Based on this principle, the fibrous foreign objects in the graphite powder can be intercepted on the roller brush 2, thereby reducing the fibrous foreign object content of the material discharged from the discharge pipe 102 and playing a filtering role.

[0029] After running for a period of time, the roller brush 2 becomes saturated with fiber foreign matter and needs to be disassembled for cleaning. Furthermore, after repeated use, the bristles 203 undergo plastic deformation, reducing their effectiveness in intercepting fiber foreign matter. Therefore, a new roller brush 2 needs to be replaced. To facilitate replacement, the roller brush 2 is designed to be detachable. A keyway 204 is provided inside the brush roller 201, and key teeth 205 are integrally formed on the roller shaft 202 to engage with the keyway 204. A collar 206 is integrally formed on the roller shaft 202. One end of the brush roller 201 abuts against the collar 206, and the other end abuts against a fixing screw 207. The fixing screw 207 is threadedly connected to the roller shaft 202. The brush roller 201 is fitted onto the roller shaft 202, with one end abutting against the collar 206 and the other end pressed against the fixing screw 207. When replacement is needed, simply remove the fixing screw 207.

[0030] Example 2: This invention provides a fiber foreign matter interception device in lithium battery graphite powder. Its overall structure is the same as that in Example 1, except that each clump of bristles 203 on the roller brush 2 includes 50 stainless steel wires with a diameter of 0.2 mm. The length of the bristles 203 protruding from the brush roller 201 is 0.5 times the diameter of the brush roller 201. The finer the diameter of the stainless steel wires of the bristles 203, the better the filtering effect on shorter fiber foreign matter. However, the bristles 203 are more easily entangled, so a larger number of stainless steel wires are required.

[0031] Example 3: This invention provides a fiber foreign object interception device in lithium battery graphite powder. Its overall structure is the same as that in Example 1, except that each cluster of bristles 203 on the roller brush 2 includes 40 stainless steel wires with a diameter of 0.3 mm. The length of the bristles 203 protruding from the brush roller 201 is 0.6 times the diameter of the brush roller 201.

[0032] Example 4: Figure 4 , Figure 5 As shown, this invention provides a fiber foreign object interception device in lithium battery graphite powder. Its overall structure is the same as in Embodiment 1, except that it also includes a negative pressure cleaning device 5. The negative pressure cleaning device 5 includes an air inlet pipe 501 and a fixed roller brush 502. The drive shaft 403 of the drive device 4 is a hollow structure, and the air inlet pipe 501 is coaxially inserted inside the drive shaft 403. One end of the air inlet pipe 501, located outside the outer casing 1, is connected to a high-pressure air source, while the other end, located inside the outer casing 1, passes through the drive shaft 403 and the turntable 3 and is connected to the fixed roller brush 502. A fixed roller brush 502 is fixedly connected, and bristles 203 are installed on the fixed roller brush 502. The fixed roller brush 502 has a hollow structure, and the hollow inner cavity of the fixed roller brush 502 is connected to the air inlet pipe 501. Several through holes 503 communicating with the hollow inner cavity are opened on the outer wall of the fixed roller brush 502. The high-pressure air source is an air compressor, which can provide high-pressure air to the hollow inner cavity of the fixed roller brush 502 through the air inlet pipe 501. The air is sprayed out from the through holes 503, which can remove the fibrous foreign matter wrapped on the bristles 203 by blowing.

[0033] The feed pipe 101 of the outer shell 1 is connected to the first valve 6, and the discharge pipe 102 is connected to the second valve 7. A cleaning pipe 103 is provided on the side wall of the outer shell 1, and the cleaning pipe 103 is connected to the third valve 8. The third valve 8 is connected to the dust collector through a pipeline. During normal operation, the first valve 6 and the second valve 7 are open, and the cavity of the outer shell 1 is connected to the feed pipe 101 and the discharge pipe 102. The third valve 8 is closed. After working for a period of time, the fiber foreign matter intercepted by the roller brush 2 gradually becomes saturated. When it is necessary to clean the fiber foreign matter wrapped on the roller brush 2, the first valve 6 is closed first to temporarily stop feeding. After the graphite powder in the outer shell 1 has flowed out, the second valve 7 is closed, and the third valve 8 is opened at the same time. The high-pressure air source is turned on, and air is sprayed through the through hole 503 of the fixed roller brush 502 for cleaning. During this period, the turntable 3 can be used to quickly rotate forward and backward to help untangle the fiber foreign matter wrapped on the bristles 203. Then, it is carried away by the airflow and finally drawn to the dust collector through the third valve 8.

[0034] Comparative Example 1:

[0035] In the above embodiment 1, 5 kg of graphite powder was taken out from the feed pipe 101 and repeatedly sieved using a vibrating screen until all the graphite powder on the screen was filtered to the underside of the screen. The screen mesh of the vibrating screen was 200 mesh. The underside of the screen was used as the processed graphite powder and the processing effect was tested in an experiment to detect the effect of fiber foreign matter treatment.

[0036] Comparative Example 2:

[0037] The overall processing method is the same as that of Comparative Example 1, except that the screen of the vibrating screen is 250 mesh.

[0038] Comparative Example 3:

[0039] The overall processing method is the same as that of Comparative Example 1, except that the screen of the vibrating screen is 300 mesh.

[0040] Experiment on the effect of fiber foreign object treatment:

[0041] Take 2.5 kg of each of the graphite powders treated in Examples 1-3 above, divide them into 3 groups, and simultaneously take untreated graphite powder at the feed pipe 101 as a control group for fiber foreign matter detection. The specific experimental steps are as follows:

[0042] S1. Preparation for foreign object detection: Cut a 250-mesh sieve into 5cm×5cm square sieves, place the sieves in a beaker, add pure water to wash, sonicate for 30 minutes, then take them out and wash them three times with pure water, and set them aside for use.

[0043] S2. Sample sieving: Pass the above-mentioned samples through a 250-mesh vibrating sieve. Weigh 2000g of the sieved sample in a beaker. Add 1600ml of anhydrous ethanol and 4000ml of pure water to the sieved sample and stir to form a slurry.

[0044] S3. Slurry filtration: Place the above 250-mesh square screen in a suction funnel, slowly pour in the slurry, and after filtration, place the square screen in a watch glass and dry it in an oven at 80°C.

[0045] S4. Counting foreign fiber objects: Place the dried square sieve under a microscope and search for foreign objects row by row from left to right along the M-shaped route. When foreign fiber objects are found, take pictures and count them.

[0046] The counting results of Examples 1-3 and the control group obtained from the experimental tests are shown in Table 1:

[0047] Table 1:

[0048]

[0049] By comparing the graphite powder treated in Examples 1-3 with the untreated graphite powder in the control group, the fiber foreign matter interception device provided by the present invention can effectively reduce the number of fiber foreign matter in graphite powder and has a good interception effect on fiber foreign matter.

[0050] Meanwhile, compared with the treatment effect of using a vibrating screen in Embodiment 2 of the present invention and Comparative Examples 1-3, the finer the screen mesh, the longer the number of filtrations and the longer the time required. Although the retention rate of fibrous foreign matter can be improved by selecting a screen with a larger mesh size, fibrous foreign matter with a length of <1000μm will pass through the mesh of the screen and mix into the undersize material after repeated sieving, and the retention effect is still not ideal.

Claims

1. A device for intercepting fibrous foreign matter in graphite powder for lithium batteries, characterized in that, The device includes a housing (1), roller brushes (2), a turntable (3), and a drive unit (4). A feed pipe (101) is provided at the top of the housing (1), and a discharge pipe (102) is provided at the bottom of the housing (1). The drive unit (4) is installed inside the housing (1). The drive unit (4) includes a fixed gear ring (401), planetary gears (402), a drive shaft (403), a reducer (404), and a drive motor (405). The fixed gear ring (401) is fixedly installed inside the housing (1). The drive shaft (403) passes through the housing (1) and is coaxially arranged with the fixed gear ring (401). The other end of the drive shaft (403) is fixedly connected to the turntable (3). The input shaft of the reducer (404) is connected to the output shaft of the drive motor (405). The reducer (404) is fixedly installed on the outside of the housing (1). Several roller brushes (2) are rotatably mounted on the turntable (3). The roller shaft (202) of the roller (201) passes through the turntable (3) and is fixedly mounted with a planetary gear (402). The planetary gear (402) meshes with the fixed gear ring (401) for transmission. The roller brush (2) includes a brush roller (201), a roller shaft (202) and brush bristles (203). The brush roller (201) is a hollow cylinder. The roller shaft (202) is coaxially fixedly mounted on the brush roller (201). The roller shaft (202) and the turntable (3) are connected by a bearing seat. Rotary connection, with several rows of bristles (203) arranged circumferentially on the outer wall of the brush roller (201); the distance between the ends of the bristles (203) of two adjacent rollers (2) is 5-10 mm; each cluster of bristles (203) includes 20-50 stainless steel wires with a diameter of 0.2-0.4 mm; the length of the bristles (203) protruding from the brush roller (201) is 0.5-0.8 times the diameter of the brush roller (201).

2. The device for intercepting fibrous foreign matter in lithium battery graphite powder according to claim 1, characterized in that, A keyway (204) is provided inside the brush roller (201). A key tooth (205) that engages with the keyway (204) is integrally formed on the roller shaft (202). A collar (206) is integrally formed on the roller shaft (202). One end of the brush roller (201) abuts against the collar (206), and the other end of the brush roller (201) abuts against the fixing screw (207). The fixing screw (207) is threadedly connected to the roller shaft (202).

3. The device for intercepting fibrous foreign matter in lithium battery graphite powder according to claim 1, characterized in that, It also includes a negative pressure cleaning device (5), which includes an air inlet pipe (501) and a fixed roller brush (502). The drive shaft (403) of the drive device (4) is a hollow structure. The air inlet pipe (501) is coaxially inserted inside the drive shaft (403). One end of the air inlet pipe (501) is located outside the housing (1) and connected to a high-pressure air source. The other end of the air inlet pipe (501) is located inside the housing (1) and passes through the drive shaft (403) and the turntable (3) to be fixedly connected to the fixed roller brush (502). A brush is installed on the fixed roller brush (502). The fixed roller brush (502) is a hollow structure. The hollow inner cavity of the fixed roller brush (502) is connected to the air inlet pipe (501). Several through holes (503) connected to the hollow inner cavity are opened on the outer wall of the fixed roller brush (502). The feed pipe (101) of the outer shell (1) is connected to the first valve (6), and the discharge pipe (102) is connected to the second valve (7). A cleaning pipe (103) is provided on the side wall of the outer shell (1). The cleaning pipe (103) is connected to the third valve (8). The third valve (8) is connected to the dust collector through a pipeline.

4. The fiber foreign matter interception device in lithium battery graphite powder according to claim 1, characterized in that, It also includes an inspection port (9), which is provided on one side of the outer shell (1). The inspection port (9) is provided with a movable sealing door (10) and the movable sealing door (10) is hinged to the outer shell (1) by a hinge.

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