System and method for manufacturing positive electrode regenerated slurry from lithium iron phosphate waste pole piece

Abstract

The invention provides a system and a method for manufacturing positive electrode regenerated slurry from a lithium iron phosphate waste pole piece, the system comprises: a pole piece crushing unit for crushing the lithium iron phosphate waste pole piece to obtain a crushed pole piece, the size of the crushed pole piece being smaller than that of the lithium iron phosphate waste pole piece; the low-temperature passivation unit is used for performing low-temperature passivation on polyvinylidene fluoride of the crushed pole piece to obtain a passivated pole piece; the screening and separating unit is used for separating the passivated pole piece to obtain a positive electrode material and an aluminum foil material; and the repairing and homogenizing unit is used for simultaneously performing crystal repairing and homogenizing on the positive electrode material to obtain regenerated slurry. According to the scheme, the regeneration efficiency of the lithium iron phosphate waste pole piece can be improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery production waste recycling technology, and in particular to a system and method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets. Background Technology

[0002] The cathode material for lithium-ion batteries can be lithium iron phosphate, ternary materials, lithium cobalt oxide, or lithium manganese oxide, among others. Batteries using lithium iron phosphate as the cathode material are called lithium iron phosphate batteries. Due to their high safety and low cost, lithium iron phosphate batteries have become one of the mainstream technologies in the fields of power batteries and energy storage batteries. Their market size has expanded rapidly, resulting in a large amount of lithium iron phosphate production waste (such as electrode sheets that fail to meet product requirements after production but before being assembled into finished batteries; in addition, electrode scraps also become lithium iron phosphate production waste).

[0003] Traditional methods for recycling lithium iron phosphate (LFP) waste employ a hydrometallurgical process based on a "material decomposition-resynthesis" approach. This process aims to chemically decompose lithium-containing battery waste (whether from production waste or retired batteries) and prepare precursor materials such as lithium carbonate and iron phosphate. Subsequently, battery material manufacturers need to resynthesize these precursors into LFP cathode materials through complex processes such as high-temperature solid-state sintering. Finally, cell manufacturers must process this recycled cathode material through a series of electrode manufacturing steps, including slurry preparation, coating, rolling, slitting, assembly, and formation, to ultimately produce battery cells. However, this approach downgrades high-value electrode materials to low-value basic chemical raw materials, requiring repeated, lengthy, and complex material synthesis and electrode manufacturing processes. This "disassemble first, rebuild later" model results in cumbersome processes, high energy consumption, long overall recycling cycles, and poor economic viability.

[0004] In view of this, there is an urgent need to provide a system and method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrodes, so as to improve the regeneration efficiency of lithium iron phosphate production waste. Summary of the Invention

[0005] This application is made in view of the aforementioned state of the prior art. The purpose of this application is to provide a system and method for manufacturing positive electrode regeneration slurry from spent lithium iron phosphate electrode sheets.

[0006] A system for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets is provided. The system includes: an electrode crushing unit for crushing the waste lithium iron phosphate electrode sheets to obtain crushed electrode sheets, wherein the size of the crushed electrode sheets is smaller than the size of the waste lithium iron phosphate electrode sheets; a low-temperature passivation unit for low-temperature passivation of the polyvinylidene fluoride (PVDF) in the crushed electrode sheets to obtain passivated electrode sheets; a screening and separation unit for separating the passivated electrode sheets to obtain positive electrode material and aluminum foil material; and a repair and homogenization unit for simultaneously performing crystal repair and homogenization on the positive electrode material to obtain regenerated slurry.

[0007] Optionally, the system further includes a slurry demagnetization unit for demagnetizing the regenerated slurry.

[0008] Optionally, the size of the broken electrode sheet is 30~200 mm.

[0009] Optionally, the operating temperature for the low-temperature passivation is 250~400℃.

[0010] Optionally, the screening and separation unit includes a multi-stage irregularly shaped vibrating screen, wherein the vibrating screen mesh of the multi-stage irregularly shaped vibrating screen is provided with multiple screen holes, wherein the multiple screen holes are evenly distributed.

[0011] Optionally, the repair and homogenization unit is provided with N-methylpyrrolidone, which serves as a grinding medium to assist in homogenization.

[0012] Optionally, the repair and homogenization unit includes one or more of a sand mill, a ball mill, a dual planetary mixer, and a twin-screw continuous pulper.

[0013] The embodiments of this application also provide a method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets. The method includes: crushing the waste lithium iron phosphate electrode sheets to obtain crushed electrode sheets; passivating the crushed electrode sheets at low temperature to obtain passivated electrode sheets; separating the passivated electrode sheets by sieving to obtain positive electrode material and aluminum foil material; and simultaneously performing crystal repair and homogenization on the positive electrode material to obtain regeneration slurry.

[0014] Optionally, the method further includes demagnetizing the recycled slurry.

[0015] Optionally, the simultaneous crystal repair and homogenization of the cathode material includes adding N-methylpyrrolidone to the cathode material to assist in homogenization.

[0016] Optionally, the crushing process of the waste lithium iron phosphate electrode sheet includes: performing multi-stage crushing on the waste lithium iron phosphate electrode sheet to reduce its size.

[0017] Optionally, the multi-stage crushing (especially the re-crushing of the crushed electrode sheets) includes: using a processing box to re-crush the crushed electrode sheets.

[0018] The system and method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets provided above, in this embodiment of the application, by setting up a repair and homogenization unit, can simultaneously repair and homogenize the positive electrode material, and obtain a regenerated slurry, thereby enabling the regeneration of the useful part of the waste lithium iron phosphate electrode sheets and improving the regeneration efficiency of the waste lithium iron phosphate electrode sheets. Attached Figure Description

[0019] Figure 1 An exemplary block diagram of a system for manufacturing positive electrode regeneration slurry from spent lithium iron phosphate electrode sheets according to one embodiment of this application is shown.

[0020] Figure 2 An exemplary structural diagram of a vibrating screen for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrodes according to one embodiment of this application is shown.

[0021] Figure 3 An exemplary block diagram of a method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets according to one embodiment of this application is shown.

[0022] Figure 4 An exemplary block diagram of a method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets, according to another embodiment of this application, is shown.

[0023] Figure 5 An exemplary structural diagram of a processing box for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets is shown, according to one embodiment of this application.

[0024] Figure 6 This paper shows a schematic diagram of the internal structure of a processing box for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets according to one embodiment of this application.

[0025] Figure 7 An exploded view of a processing box for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets according to one embodiment of this application is shown.

[0026] Figure 8 An exemplary structural diagram of the removal shell of a processing box for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrodes according to one embodiment of this application is shown.

[0027] Figure 9 The particle size distribution of the regenerated slurry produced from the positive electrode regeneration slurry of waste lithium iron phosphate electrode sheets is shown in one embodiment of this application. Detailed Implementation

[0028] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0029] It should be understood that the electrode can be a positive electrode, which may include a current collector, an active material, and a binder. The active material may include lithium iron phosphate (LiFePO4) powder, the current collector may include aluminum foil, and the binder may include PVDF (polyvinylidene fluoride). Furthermore, the lithium iron phosphate powder can be adhered to the aluminum foil using PVDF.

[0030] like Figure 1 As shown, the system for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrodes includes: an electrode crushing unit 10, used to crush waste lithium iron phosphate electrodes to obtain crushed electrodes, wherein the size of the crushed electrodes is smaller than the size of the waste lithium iron phosphate electrodes.

[0031] The electrode crushing unit 10 may include crushing equipment, such as a double-toothed roll crusher, a single-toothed roll crusher, or a shear crusher. By using one or more of the aforementioned crushing equipment, the crushing of waste lithium iron phosphate electrodes can be achieved.

[0032] It is understandable that crushing equipment can be divided into coarse crushers and fine crushers based on the size of the resulting electrode sheets or the crushing method.

[0033] It is understood that the electrode crushing unit 10 can crush waste lithium iron phosphate electrodes once or multiple times. The electrode crushing unit 10 may include a single-stage crushing unit (which can crush waste lithium iron phosphate electrodes once) or a multi-stage crushing unit. Preferably, a multi-stage crushing unit can be used to crush waste lithium iron phosphate electrodes multiple times to reduce the size of the resulting crushed electrodes.

[0034] For example, a multi-stage crushing unit may include a first crushing unit and a second crushing unit. The first crushing unit may include a coarse crusher, which can crush large, irregular, and possibly tangled whole electrode sheets into smaller electrode sheets through a low-speed, high-torque shearing method.

[0035] Furthermore, the second crushing unit may include a fine crusher, which can further crush the electrode sheets crushed by the first crushing unit to further reduce the size of the electrode sheets. It should be understood that the second crushing unit can further crush the sheet-like electrode sheets into smaller particles through a combination of hammering, impact, shearing, and other actions.

[0036] Optionally, the length and width of the crushed electrode obtained after processing by the second crushing unit can both be 30~200 mm. It is understood that the output end of the electrode crushing unit 10 can be connected to the input end of the low-temperature passivation unit 20. If the size of the electrode is larger than the feed inlet of the low-temperature passivation unit 20, it may cause blockage due to the size exceeding the channel diameter (e.g., the electrode wrapping around the conveyor shaft or blocking the feed inlet), resulting in feed interruption. By crushing the electrode into smaller pieces, the feed interruption when the electrode enters the low-temperature passivation unit 20 can be avoided, thus achieving stable feeding to the screening and separation unit 30.

[0037] The low-temperature passivation unit 20 is used to passivate the broken polyvinylidene fluoride (PVDF) of the electrode at low temperatures to obtain a passivated electrode. It is understood that by placing the broken electrode in the low-temperature passivation unit, the properties of the PVDF can be altered, reducing its viscosity. This significantly weakens the binding force between the PVDF and the lithium iron phosphate active material and current collector, facilitating subsequent efficient physical separation (e.g., vibration, sieving).

[0038] Optionally, the operating temperature of the low-temperature passivation unit 20 can be 250~400℃. Existing passivation processes typically operate at 400~600℃, at which point the electrochemical performance of lithium iron phosphate may be compromised. For example, the crystal structure of lithium iron phosphate may be damaged. Furthermore, the carbon layer structure on the lithium iron phosphate may be burned away, exposing the surface.

[0039] By setting the operating temperature of low-temperature passivation to 250~400℃, it consumes less energy compared to existing passivation methods and can protect the electrochemical performance of the positive electrode active material (i.e., lithium iron phosphate), which facilitates subsequent direct repair and regeneration.

[0040] In some embodiments, the low-temperature passivation unit 20 may include a feeding system, passivation equipment, a heating and temperature control system, an atmosphere system, and a discharging and cooling system.

[0041] Specifically, the aforementioned feeding system may include a screw feeder or a vibrating feeder, which can uniformly and controllably feed the crushed electrode sheets into the passivation treatment equipment.

[0042] The aforementioned passivation treatment equipment (i.e., heating reactor) may include roller kilns, rotary kilns, tube furnaces, and box furnaces, etc. The crushed electrode sheets can be heated within the passivation treatment equipment. A heating and temperature control system can be installed within the passivation treatment equipment. This system can heat the passivation treatment equipment and control the temperature of different areas within the equipment, ensuring that the crushed electrode sheets are adequately treated within the target range (e.g., 250~400℃).

[0043] Furthermore, the atmosphere system may include an inert gas source, pressure gauge, flow meter, and gas pipelines. This atmosphere system can introduce inert gas (such as nitrogen, argon, helium, etc.) into the passivation equipment, thereby expelling air (such as oxygen) from the passivation equipment and creating an oxygen-free environment to prevent oxidation of lithium iron phosphate materials. It should be understood that the purity of the aforementioned inert gas can be greater than or equal to 99.99%.

[0044] The discharge and cooling system can discharge and cool the broken electrode sheets after low-temperature passivation, preventing them from oxidizing due to prolonged exposure to air at high temperatures. It is understood that after processing the broken electrode sheets through the low-temperature passivation unit 20, passivated electrode sheets can be obtained.

[0045] The screening and separation unit 30 is used to separate the passivated electrode sheets to obtain positive electrode material and aluminum foil material. It is understood that the feeding end of the screening and separation unit 30 can be connected to the discharge end of the low-temperature passivation unit 20. The passivated electrode sheets, after passivation, can be conveyed from the discharge end of the low-temperature passivation unit 20 to the feeding end of the screening and separation unit 30 (e.g., via conveyor belt), and then screened and separated in the screening and separation unit 30.

[0046] Optionally, the screening and separation unit 30 may include a multi-stage irregularly shaped vibrating screen, wherein the vibrating screen mesh 31 of the multi-stage irregularly shaped vibrating screen is provided with a plurality of screen holes 32, wherein the plurality of screen holes 32 are evenly distributed.

[0047] It is understood that the irregularly shaped vibrating screen can be set to one stage or multiple stages. Furthermore, the multi-stage irregularly shaped vibrating screen may include multiple vibrating screens 31, which can be staggered. For example, there may be a preset angle between the relative screen holes 32 of two adjacent vibrating screens 31. This preset angle can be the angle formed by the center lines of different screen holes 32.

[0048] These multiple screen holes 32 on a vibrating screen 31 can be arranged collinearly or parallel to each other (e.g. Figure 2 As shown in the figure, the uniform distribution of multiple sieve holes 32 may include: the distance between adjacent collinear sieve holes 32 can be a fixed value, and the distance between two adjacent parallel sieve holes 32 can also be a fixed value. It should be understood that the distance between adjacent sieve holes 32 can be the distance between the axes of symmetry of adjacent sieve holes or the distance between the center lines.

[0049] It is necessary to understand that, such as Figure 2 As shown, the sieve hole 32 can be circular or near-circular, rectangular or near-rectangular, or other polygonal shapes, etc.

[0050] Preferably, the sieve hole 32 can be rectangular or rectangular, and it can be elongated.

[0051] Furthermore, when the sieve hole 32 is elongated, the length of the elongated sieve hole can be 15 mm to 150 mm (e.g., 15 mm, 60 mm, 105 mm or 150 mm, etc.); the width can be 1 mm to 5 mm (e.g., 1 mm, 3 mm and 5 mm, etc.).

[0052] It is understood that the passivated electrode may include aluminum foil fragments and positive electrode material coating (i.e. lithium iron phosphate active material) peeled off from the aluminum foil. The aforementioned aluminum foil fragments may be sheet-like or rolled structures with a certain length and width, and the aforementioned positive electrode material coating may be small in size, thereby allowing the two to be separated.

[0053] Specifically, after crushing and passivation, the flexible aluminum foil can be rolled up or formed into sheets, while the brittle lithium iron phosphate active material can be in irregular blocks or granules. The elongated sieve openings provide a long, narrow opening in two dimensions, allowing the blocky or granular lithium iron phosphate active material to pass through and become the undersize. Aluminum foil fragments, due to their larger size, can remain on the elongated sieve openings rather than passing vertically through this narrow channel, thus being more easily retained as the oversize.

[0054] The lithium iron phosphate active material that becomes the undersize can enter the repair and homogenization unit 40 for further processing, while the aluminum foil fragments that become the oversize can be recycled and utilized.

[0055] The repair and homogenization unit 40 is used to simultaneously repair and homogenize the cathode material to obtain a regenerated slurry. The feed inlet of the repair and homogenization unit 40 can be connected to the discharge outlet of the screening and separation unit 30, allowing the undersize material from the screening and separation unit 30 to enter the repair and homogenization unit 40. It is understood that the main component of the undersize material entering the repair and homogenization unit 40 at this time is blocky or granular lithium iron phosphate active material.

[0056] Optionally, the repair and homogenization unit contains N-methylpyrrolidone (NMP), which can be used as a grinding medium to assist in homogenization. It should be understood that NMP can include micro-electrical grade NMP, battery-grade NMP, pharmaceutical-grade NMP, and industrial-grade NMP; this application may use micro-electrical grade NMP or battery-grade NMP.

[0057] Optionally, the repair and homogenization unit 40 may include one or more of a sand mill, a ball mill, a dual planetary mixer, and a twin-screw continuous pulper. It should be understood that the aforementioned sand mill, ball mill, dual planetary mixer, and twin-screw continuous pulper can be used individually or in combination.

[0058] It should be understood that the aforementioned sand mill, ball mill, double planetary mixer, and twin-screw continuous pulping machine can perform crystal repair on lithium iron phosphate active materials. Furthermore, by setting up a battery-grade NMP, homogenization can be performed simultaneously with crystal repair.

[0059] It is understandable that by repairing the crystals of the aforementioned lithium iron phosphate active material, it can be reused as an active material for the positive electrode.

[0060] Furthermore, one or more of the following can be provided in the repair and homogenization unit 40: conductive agent (e.g., carbon black or conductive graphite), binder (e.g., polyvinylidene fluoride PVDF), and dispersant (e.g., NMP). The repair and homogenization unit 40 can continuously perform stirring, so that the repaired lithium iron phosphate active material, conductive agent, and binder are mixed with the assistance of NMP. The repaired lithium iron phosphate active material, conductive agent, and binder can be uniformly suspended in the NMP dispersant to prevent sedimentation and form a well-dispersed slurry.

[0061] It is important to understand that in the existing technology, after the active material of lithium iron phosphate is crystal repaired, it needs to be cooled and removed from the furnace, and then crushed and depolymerized to form powder. The powder can then be stored and transferred. When homogenization is required, the powder is dry premixed before the active material of lithium iron phosphate can be homogenized.

[0062] By using one or more of a sand mill, ball mill, dual planetary mixer, and twin-screw continuous slurry mill in the repair and homogenization unit 40, and by incorporating battery-grade NMP, the lithium iron phosphate material obtained after treatment in the low-temperature passivation unit 20 is crystal repaired while the lithium iron phosphate material and NMP are mixed and homogenized. Compared with the prior art, this method can regenerate the useful part (e.g., lithium iron phosphate material) of the waste lithium iron phosphate electrode sheet, while reducing the steps of cooling and unloading, crushing and depolymerization, storing and transferring the powder, and dry premixing the powder. Therefore, it can improve the regeneration efficiency of the waste lithium iron phosphate electrode sheet and reduce the cost.

[0063] It should be understood that the solid content of the recycled slurry can range from 40% to 75%. It is also understood that the viscosity of the recycled slurry can be controlled by adjusting the content of the binder (PVDF), the particle size distribution of the lithium iron phosphate material, and the surface charge content. Furthermore, the viscosity of the recycled slurry can range from 4000 to 10000 mPa·s.

[0064] Optionally, the system for manufacturing positive electrode regeneration slurry from spent lithium iron phosphate electrodes also includes a slurry demagnetization unit 50, which can be used to demagnetize the regeneration slurry.

[0065] Understandably, during the initial processing of recycled slurry, metal debris from equipment wear and iron powder from component friction may become mixed in. During battery charging and discharging, these conductive, hard particles may puncture the separator, causing an internal short circuit and triggering thermal runaway. Furthermore, these magnetic foreign objects can form tiny conductive bridges, accelerating battery charge loss.

[0066] It should be understood that the slurry demagnetizing unit 50 may include an electromagnetic demagnetizing device. Furthermore, the electromagnetic demagnetizing device can be configured accordingly based on the distribution characteristics of magnetic impurities.

[0067] For example, the pipe diameter of the electromagnetic demagnetizing equipment can be determined based on the viscosity of the slurry, thus ensuring smooth and unobstructed flow of the slurry within the pipe. Furthermore, by extending the pipe or reducing the slurry flow rate, the residence time of the slurry in the magnetic field can be increased, allowing sufficient time for magnetic impurities in the slurry to be captured.

[0068] Furthermore, the strength of the magnetic field can be determined based on the particle size of the slurry. It's understandable that, due to the small particle size of the slurry, the magnetic foreign matter introduced by the upstream processes is mostly micron-sized iron filings and worn metal, which are small in mass and experience little magnetic force after magnetization. Therefore, the electromagnetic demagnetizing equipment can be set to a high-gradient magnetic field, thereby improving demagnetization efficiency.

[0069] The magnetic field strength within the slurry demagnetizing unit 50 can be 8000~13000 Gs.

[0070] By setting up the slurry demagnetization unit 50, magnetic foreign matter introduced by the front-end processing units at each stage during the slurry preparation process of lithium iron phosphate waste production electrode sheets can be accurately adsorbed and separated, thereby eliminating the potential impact of magnetic foreign matter on the electrochemical performance of regenerated batteries and ensuring that product quality meets the production standards of the lithium battery industry.

[0071] like Figure 3As shown, the embodiments of this application provide a method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets. The method includes: step S310, crushing the waste lithium iron phosphate electrode sheets to obtain crushed electrode sheets; step S320, low-temperature passivation of the crushed electrode sheets to obtain passivated electrode sheets; step S330, sieving and separating the passivated electrode sheets to obtain positive electrode material and aluminum foil material; and step S340, simultaneously performing crystal repair and homogenization on the positive electrode material to obtain regeneration slurry.

[0072] In one possible implementation, such as Figure 4 As shown, the method may further include: step S350, demagnetizing the regenerated slurry.

[0073] Steps S310 to S350 can be implemented by the electrode crushing unit 10, the low-temperature passivation unit 20, the screening and separation unit 30, the repair and homogenization unit 40, and the slurry demagnetization unit 50, respectively. For details, please refer to the descriptions of these units above. The method for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrodes according to the embodiments of this application can achieve the same beneficial effects as described above, and will not be repeated here.

[0074] In one possible implementation, the crushing process for waste lithium iron phosphate electrodes includes multi-stage crushing of the waste lithium iron phosphate electrodes to reduce their size.

[0075] In one possible implementation, multi-stage crushing, particularly the re-crushing of the crushed electrode sheets, includes: re-crushing the crushed electrode sheets using a processing chamber 11. It is understood that the crushed electrode sheets can undergo secondary or tertiary crushing, etc.

[0076] It should be understood that the electrode crushing unit 10 may include primary crushing equipment and secondary crushing equipment, wherein the secondary crushing equipment may include a processing box 11. The processing box 11 may be configured as a cylinder or a polygonal prism (e.g., Figure 5 (as shown in the image) etc.

[0077] Processing box 11 may include feed pipe 12 (e.g. Figure 5 As shown), the feed pipe 12 can be set on the side of the processing box 11. The top end of the feed pipe 12 is fixedly fitted with a mounting flange 13. The mounting flange 13 can be fixedly installed at the discharge port of the primary crushing equipment by bolts. The electrode sheets crushed by the primary crushing equipment can enter the processing box 11 through the feed pipe 12.

[0078] Furthermore, a sealing cover 14 may be provided on the top of the processing box 11 (e.g., Figure 5 and Figure 7As shown), an air pump 15 may be provided on the sealing cover 14. The air pump 15 may at least partially (e.g., the air outlet end of the air pump 15) penetrate the sealing cover 14 and be connected to the top of the air inlet pipe 16 located inside the processing box.

[0079] Processing box 11 may also include a filter discharge plate 102 (e.g. Figure 6 (As shown). The filter discharge plate 102 can be disposed in the lower part of the interior of the processing box 11 and connected to the inner wall of the processing box 11. It can be disposed parallel or approximately parallel to the bottom of the processing box 11. It should be understood that the filter discharge plate 102 can be disposed at the outlet of the feed pipe 12 and below the cutting blade 19, so that the electrode sheet coming out of the outlet of the feed pipe 12 can slide onto the filter discharge plate 102.

[0080] like Figure 5 and Figure 7 As shown, the top end of the air intake pipe 16 can be connected to the air pump 15, and the gas output by the air pump 15 can flow outward along the air intake pipe 16.

[0081] The inner wall of the air intake pipe 16 can be movably inserted into the outer wall of the lifting pipe 17. A cutting motor 18 is fixedly connected to the top of the lifting pipe 17. It is understood that the cutting motor 18 can also extend into the interior of the air intake pipe 16. The lifting pipe 17 is connected to the top of the connecting shaft 101, and the bottom of the connecting shaft 101 is connected to at least one set of cutting blades 19.

[0082] The side of the processing box 11 may be provided with an opening, and a vertical plate 113 (e.g., ...) may be provided in this opening. Figure 5 and Figure 7 (As shown) to isolate the inner and outer sides of the processing box 11. The vertical plate 113 can be made of transparent material, so that during the secondary crushing of the electrode sheets, the transparent vertical plate 113 can facilitate the user to observe the state of the electrode sheet crushing inside the processing box 11.

[0083] During the operation of the system in this application, the electrode sheets processed by the primary crushing equipment will fall from the discharge port into the feed pipe 12, and then slide from the outlet of the feed pipe 12 onto the filter discharge plate 102. After that, the air pump 15 is started, and its air outlet is used to input gas into the air inlet pipe 16, so as to increase the pressure in the air inlet pipe 16. Under the pushing action of the gas, the lifting pipe 17 will move downward, thereby driving the connecting shaft 101 and the cutting blade 19 connected to the lifting pipe 17 to move downward together.

[0084] Furthermore, the cutting motor 18 can be started, so that its output end drives the lifting tube 17, the connecting shaft 101 and the cutting blade 19 to rotate together, thereby using the cutting blade 19 to perform secondary crushing on the larger electrode sheet;

[0085] During the crushing process, the lifting pipe 17 continues to move downward so that the cutting blade 19 can apply pressure to the electrode and cut it, which can optimize the crushing effect of the electrode. The electrode after secondary crushing will pass through the filter discharge plate 102 and enter the low temperature passivation unit 20 for processing.

[0086] After the crushing process is completed, the gas in the air inlet pipe 16 can be taken out, so that the air inlet pipe 16 is in a negative pressure state, so as to suck up the lifting pipe 17 to move and reset.

[0087] In one possible implementation, simultaneously performing crystal repair and homogenization on the cathode material includes adding N-methylpyrrolidone to the cathode material to assist in homogenization.

[0088] Table 1 records the performance data of different standard samples and their corresponding regenerated samples in various specific embodiments of this application. Table 2 records the test data of the standard samples and their corresponding regenerated samples obtained by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0089] Table 1 Performance data of different standard samples and their corresponding regenerated samples

[0090]

[0091] Table 2 Comparison of test data obtained by ICP-OES for standard samples and corresponding regenerated samples

[0092]

[0093] like Figure 9 As shown in Tables 1 and 2, it should be understood that the standard sample can be a slurry sample obtained by manufacturing cathode regeneration slurry according to existing methods, and the regenerated sample can be a slurry sample obtained by manufacturing cathode regeneration slurry for spent lithium iron phosphate electrodes according to the method of this application.

[0094] Table 1 shows that the 0.1C charge specific capacity of the regenerated samples obtained by the method of this application in Example 1 and Example 2 is close to (slightly lower than) the 0.1C charge specific capacity of the standard sample.

[0095] Table 2 shows that the contents of Li, Fe, and P in the standard sample obtained by the method of this application are close to the contents of the standard sample.

[0096] Furthermore, such as Figure 3 As shown, the volume density of the regenerated samples with particle sizes of 0.6~1.1 μm obtained by the method of this application is greater than or equal to 5%.

[0097] Therefore, the method of this application improves the regeneration efficiency while the obtained slurry sample still has good performance.

[0098] It should be understood that at least some aspects or features of the above-described implementation methods, embodiments, or examples can be appropriately combined.

[0099] It is understood that, in this application, when the number of parts or components is not specifically limited, the number can be one or more, where multiple refers to two or more. For cases where the number of parts or components shown in the drawings and / or described in the specification is, for example, two, three, four, etc., this specific number is generally exemplary and not restrictive, and can be understood as multiple, i.e., two or more; however, this does not mean that this application excludes the case of one.

[0100] In this application, unless otherwise expressly stated or limited, terms such as "installation," "assembly," "connection," "linking," "joining," "linking," "abutment," "communication," "connection," "conduction," "fixing," and "fastening" should be interpreted broadly, for example, they can be direct or indirect. For instance, regarding connection, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly stated or limited. For instance, regarding communication / conduction, it can be direct communication / conduction or indirect communication / conduction through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0101] In this application, unless otherwise expressly stated or limited, a component being disposed / installed / located / accommodated / enclosed / placed within, inside, or within another component, or a component being inserted / extended / extended into or into another component, can be either of the following two situations: a portion or a majority of the one component is located within the other component; or the one component is completely accommodated / received within the other component.

[0102] It should be understood that the above-described embodiments, examples, or examples are merely exemplary and are not intended to limit this application. Those skilled in the art can make various modifications and changes to the above-described embodiments, examples, or examples under the teachings of this application without departing from the scope of this application.

Claims

1. A system for manufacturing positive electrode regeneration slurry from waste lithium iron phosphate electrode sheets, characterized in that, The system includes: An electrode crushing unit (10) is used to crush the waste lithium iron phosphate electrode to obtain crushed electrode, wherein the size of the crushed electrode is smaller than the size of the waste lithium iron phosphate electrode. The low-temperature passivation unit (20) is used to passivate the polyvinylidene fluoride of the broken electrode at a low temperature to obtain a passivated electrode. The sieving and separation unit (30) is used to separate the passivated electrode to obtain positive electrode material and aluminum foil material; The repair and homogenization unit (40) is used to simultaneously repair and homogenize the cathode material to obtain a regenerated slurry.

2. The system according to claim 1, characterized in that, The system further includes a slurry demagnetization unit (50) for demagnetizing the regenerated slurry.

3. The system according to claim 1, characterized in that, The length and width of the broken electrode are both 30~200 mm.

4. The system according to claim 1, characterized in that, The operating temperature for the low-temperature passivation is 250~400℃.

5. The system according to claim 1, characterized in that, The screening and separation unit (30) includes a multi-stage irregularly shaped vibrating screen, wherein the vibrating screen mesh (31) of the multi-stage irregularly shaped vibrating screen is provided with a plurality of screen holes (32), wherein the plurality of screen holes (32) are evenly distributed.

6. The system according to claim 1, characterized in that, The repair and homogenization unit (40) contains N-methylpyrrolidone, which serves as a grinding medium to assist in homogenization.

7. The system according to any one of claims 1 to 6, characterized in that, The repair and homogenization unit (40) includes one or more of the following: a sand mill, a ball mill, a double planetary mixer, and a twin-screw continuous pulper.

8. A method for manufacturing positive electrode regeneration slurry from spent lithium iron phosphate electrode sheets, characterized in that, The method includes: The waste lithium iron phosphate electrode sheets are crushed to obtain crushed electrode sheets; The broken electrode sheet is passivated at low temperature to obtain a passivated electrode sheet; The passivated electrode sheets are separated by sieving to obtain positive electrode material and aluminum foil material; The cathode material is simultaneously subjected to crystal repair and homogenization to obtain a regenerated slurry.

9. The method according to claim 8, characterized in that, The method also includes demagnetizing the recycled slurry.

10. The method according to claim 8, characterized in that, The simultaneous crystal repair and homogenization of the cathode material includes adding N-methylpyrrolidone to the cathode material to assist in homogenization.

11. The method according to claim 8, characterized in that, The crushing process of the waste lithium iron phosphate electrode sheets includes: The waste lithium iron phosphate electrode sheets are subjected to multi-stage crushing to reduce their size.

12. The method according to claim 11, characterized in that, The multi-stage crushing includes: using a processing box to perform secondary crushing on the crushed electrode sheets.

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