Method and device for preparing dry-method electrode by using waste positive plate without liquid injection

Abstract

The invention belongs to the technical field of lithium ion battery waste recycling and regeneration, and particularly relates to a method and device for preparing a dry-method electrode by using a non-liquid-injection waste positive plate. The method comprises the steps that a waste production pole plate is pretreated through a pretreatment unit, and the pretreatment unit conducts crushing treatment on the large-size pole plate through crushing equipment; the size of the pole piece reaches the size range required by the subsequent process, and materials which do not meet the size requirement are preliminarily separated by virtue of a screening function in the crushing equipment; according to the method for preparing the dry-method electrode by using the waste positive plate without liquid injection, high-economy stripping recovery and recycling of the dry-method electrode are realized, the waste recycling efficiency is remarkably improved, the recovery cost is reduced, meanwhile, by virtue of a dry-method electrode process, the efficient secondary utilization of an original PVDF binder in a stripping material is realized by optimizing process parameters, and the production cost is reduced. New material consumption is reduced, process steps are simplified, and therefore production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery waste recycling technology, specifically a method and apparatus for preparing dry electrodes using unfilled waste positive electrode sheets. Background Technology

[0002] With the rapid development of the new energy industry, lithium iron phosphate (LFP) and other cathode materials have gained widespread application due to their high safety and low cost advantages. Currently, lithium-ion battery electrode manufacturing generally adopts wet processing, which has inherent drawbacks including process efficiency and performance bottlenecks. Wet processing requires multiple steps such as mixing, coating, drying, and rolling, which is lengthy and energy-intensive. In particular, the solvent-dependent nature of the process severely limits the coating thickness of the active material (usually ≤150μm), hindering the development of high-energy-density batteries.

[0003] The extensive use of organic solvents has significant negative impacts, including: health hazards, as N-methylpyrrolidone (NMP) is an essential solvent, and the VOCs released from its volatilization directly threaten the health of workers; high costs, as the energy consumption of organic solvent recycling accounts for more than 50% of the total energy consumption in electrode preparation, and related equipment costs account for more than 20%, making these processes a major component of manufacturing costs; and environmental risks, as NMP residues have bioaccumulative toxicity, and improper handling will cause persistent pollution.

[0004] The dilemma of recycling waste electrode sheets: According to statistics, the wet process generates about 200 tons of unfilled waste positive electrode sheets (i.e., defective products without electrolyte) for every 1 GWh of battery produced. This type of waste contains high-value positive electrode materials, conductive agents and PVDF binders. The current mainstream disposal method is to sell them to powdering companies at low prices, resulting in significant resource waste and economic value loss. To address this, the present invention provides a method and apparatus for preparing dry electrodes using unfilled waste positive electrode sheets. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for preparing a dry electrode using unfilled waste positive electrode sheet, comprising the following steps: S1: The waste production electrode sheets are pre-treated by the pre-treatment unit. The pre-treatment unit crushes the large-sized electrode sheets with crushing equipment to bring the electrode sheet size into the size range required by the subsequent process. With the help of the screening function in the crushing equipment, materials that do not meet the size requirements are initially separated. S2: The pretreatment unit uses an airflow separator to specifically remove extremely small-sized electrode sheets generated during the crushing process, as well as metal scraps, fibers, and other foreign matter mixed in with the raw materials. S3: The electrode sheet after being processed by the pretreatment unit enters the back-end material regeneration unit. The material regeneration unit adopts a low-temperature pyrolysis process. After low-temperature pyrolysis treatment, the positive electrode sheet can be separated into two parts: positive electrode material with its own PVDF and aluminum foil. The aluminum foil can be collected and recycled using an airflow separator. S4: The positive electrode material with PVDF obtained after low-temperature pyrolysis will enter the electrode preparation unit for electrode preparation. The electrode preparation unit includes four sequential processes: primary ball milling, secondary ball milling, airflow shearing and hot rolling, to prepare regenerated electrode sheets.

[0007] The steps for using the airflow separator include: A1: The second discharge port is sealed by the moving plate, and the sealing plate seals the port of the first storage tank. The raw material processed by the pretreatment unit is fed into the feeding chamber from the first feeding tank. After that, the raw material will pass through the impurity removal zone. A2: When the raw materials pass through the impurity removal zone, the gas generated by the air pump blows away the metal scraps, fibers and other foreign objects mixed in with the raw materials. The gas will carry the foreign objects from the second feed trough into the first storage tank. A3: The first discharge port is sealed by a moving plate, and the sealing plate seals the port of the second storage tank. Then, the mixture of positive electrode material and aluminum foil is put into the impurity removal zone. At this time, the gas blows the aluminum foil into the second storage tank for storage, to be recycled later.

[0008] Preferably, the dry electrode preparation method includes three adjacent and sequentially progressive process units: a pretreatment unit, a material regeneration unit, and an electrode preparation unit. The pretreatment unit, as the first process unit in the dry electrode preparation method of the present invention, includes two sequentially progressive steps: crushing and impurity removal. Its purpose is to remove impurities from the raw materials and cut them to a suitable size, thereby providing a reliable guarantee for the processing effect of subsequent units.

[0009] Preferably, the crushing process involves refining large-sized electrode sheets using crushing equipment to bring the sheet size within the range required for subsequent processes. Simultaneously, the equipment's screening function initially separates materials that do not meet size requirements during crushing, ensuring good uniformity in the size of materials entering the later stages. The electrode sheet crushing size is 200–1000 mm. The crushing equipment includes, but is not limited to, shear crushers, double-toothed roller crushers, single-toothed roller crushers, and jaw crushers.

[0010] Preferably, the impurity removal process is specifically designed to remove extremely small electrode sheets generated during the crushing process, as well as metal scraps, fibers, and other foreign matter mixed in with the raw materials. This prevents these impurities from adversely affecting the conductivity, bonding strength, or structural integrity of the electrodes in subsequent processes, thus ensuring the purity of the raw materials from the source. The equipment used for the impurity removal process is an airflow separator.

[0011] Preferably, the electrode sheet that has undergone the impurity removal process enters the downstream material regeneration unit. The purpose of the material regeneration unit is to achieve efficient separation of the positive electrode active material and the current collector in the electrode sheet. The material regeneration unit adopts a low-temperature pyrolysis process. Under the protection of an inert atmosphere, the process achieves moderate pyrolysis of polyvinylidene fluoride (PVDF) in the waste lithium iron phosphate positive electrode sheet through a selected pyrolysis temperature. This ensures efficient separation of the positive electrode active material and the current collector while retaining most of the PVDF for downstream reuse.

[0012] Preferably, the low-temperature pyrolysis temperature range is 150–300°C, and the pyrolysis time is 0.5–1 hour. The inert gas includes, but is not limited to, nitrogen, argon, and a mixture of argon and hydrogen, while ensuring that the oxygen content does not exceed 50 ppm.

[0013] Preferably, the low-temperature pyrolysis equipment is a rotary kiln with a built-in screen at the tail end. During operation, the rotary kiln uses lifters on its inner wall to evenly rotate the electrode material axially, ensuring the material is fully heated in a pre-set low-temperature pyrolysis atmosphere. This promotes the appropriate decomposition of the binder on the electrode surface, thereby achieving the pyrolytic separation of the active material from the current collector. After processing by the low-temperature pyrolysis process, the waste lithium iron phosphate cathode sheet can be separated into two parts: one is cathode material retaining most of the PVDF (80wt%), and the other is aluminum foil. When the material rotates to the tail end of the cylinder, it can be discharged into an air classifier. Based on the difference in weight between the aluminum foil and the cathode material, the two are screened, ultimately achieving efficient separation. The aluminum foil will be collected and recycled, while the cathode material will enter the downstream electrode preparation unit for further processing.

[0014] Preferably, the PVDF-containing cathode material obtained after the above-mentioned low-temperature pyrolysis process will be fed into the electrode preparation unit for electrode preparation. The PVDF-containing cathode material first undergoes a ball milling process, the purpose of which is to achieve homogenization of the cathode material itself. The grinding time of the ball milling process is 0.5 to 12 hours, and the particle size of the material after the ball milling process should meet the requirements of Dmax≤50maxμm and D50≤20μm.

[0015] Preferably, the cathode material, after homogenization through a primary ball milling process, enters a secondary ball milling process. In this process, auxiliary materials are added, and the secondary ball milling ensures thorough mixing of the cathode material and the newly added auxiliary materials to guarantee that the performance of the electrode sheet prepared in the later stages meets the standards. The grinding time for the secondary ball milling process is 0.5–6 hours.

[0016] Preferably, the auxiliary materials added in the secondary ball milling process are: PTFE, a conductive agent, and a new positive electrode active material. The PTFE is a high-molecular-weight fluoropolymer, intended to further improve the bonding performance of the electrode material and ensure stable bonding of each component during subsequent processing and use. The conductive agent is a material with excellent conductivity, such as carbon black or carbon nanotubes, which helps to construct a continuous conductive network, reduce the internal resistance of the electrode, and improve electron conduction efficiency. The new positive electrode active material is a commercially available, smaller-particle-size positive electrode active material, intended to fill the gaps between the original positive electrode material particles, optimize the material's packing density, increase the contact area between the active material and the electrolyte, and improve the ion diffusion rate, thereby further improving the electrochemical performance of the prepared electrode. The dosage of the PTFE auxiliary material is 0.5%–3%, the dosage of the conductive agent is 0.5%–2%, and the dosage of the positive electrode active material is 1%–48%, with Dmax ≤ 10 μm and D50 ≤ 1.18 μm.

[0017] Preferably, the material after the secondary ball milling process has achieved homogeneous mixing of recycled material and added auxiliary materials, and then enters the airflow shearing process. The purpose of this process is to form a continuous fiber structure of the binder through high-speed airflow shearing, so as to enhance the interfacial bonding between components, reduce the risk of delamination and detachment in subsequent processing, and improve the overall toughness of the material, so as to provide a guarantee for the densification of the electrode sheet in the hot roll pressing process, and ultimately improve the mechanical strength and charge-discharge cycle stability of the prepared electrode sheet. The airflow shearing process uses a high-speed airflow with an airflow velocity of 40-60 m / s to form a shear force field, the residence time of the material in the shearing chamber is controlled to be 10-20 min, and the temperature in the chamber is maintained at 60-80℃. Preferably, the material processed by the airflow shearing process enters the hot rolling process, where it is hot rolled at 150–200°C. Simultaneously, the rolling pressure is controlled at 5–10 MPa and the roller linear speed at 2–3 m / min. By precisely adjusting the roller spacing, a self-supporting electrode film with a thickness of 250–300 μm is formed. These optimized operating parameters promote thorough densification of the material under the combined action of heat and mechanical force, while allowing the PVDF, PTFE, and other binders to melt moderately and distribute evenly at low temperatures. This ensures the film has good self-supporting properties while avoiding excessive compaction that could damage the active material particles, providing a structurally stable and uniformly performing regenerated electrode sheet for subsequent battery assembly.

[0018] An apparatus for preparing dry electrodes using unfilled waste positive electrode sheets is disclosed. This apparatus is applicable to the aforementioned method for preparing dry electrodes. The airflow separator includes a feeding chamber and a removal chamber. A first feeding trough is formed on the top surface of the airflow separator, and a first discharge trough is formed on the bottom surface. An installation area is formed on the side wall of the airflow separator for installing an air pump. A side plate is provided within the installation area. A set of air outlets communicating with the installation area is formed on the inner wall of the removal chamber. A first storage tank and a second storage tank are provided within the airflow separator. A second feeding trough communicating with the first storage tank is formed on the inner wall of the removal chamber. A first discharge port communicating with the first storage tank is formed on the bottom surface of the airflow separator, and a second discharge port communicating with the second storage tank is also formed on the bottom surface. A first sealing assembly is provided within the airflow separator to seal the first and second discharge ports, and a second sealing assembly is provided within the airflow separator to seal the ports of the first and second storage tanks.

[0019] Preferably, the first sealing assembly includes a groove formed on the side wall, the groove being connected to a first discharge port and a second discharge port, a movable plate sliding inside the groove, a through groove formed on the movable plate, and a filter screen fixedly connected to the inner wall of the through groove.

[0020] Preferably, a first connecting plate is fixedly connected to the side wall of the airflow separator. A first movable groove communicating with the slide is opened on the side of the first connecting plate near the airflow separator. A rotating shaft is rotatably connected in the first movable groove. A motor for driving the rotating shaft is provided on the first connecting plate. A connecting line is fixedly connected to the rotating shaft. The end of the connecting line away from the rotating shaft is fixedly connected to the movable plate. A first spring is fixedly connected between the end of the movable plate away from the connecting line and the inner wall of the slide.

[0021] Preferably, the second sealing assembly includes a second connecting plate fixed to the side wall of the airflow separator. A second moving groove is provided on the side of the airflow separator closest to the airflow separator. A sealing plate is slidably connected in the second moving groove. A third feeding groove is provided on the sealing plate. A connecting pipe communicating with the second feeding groove is provided on the second connecting plate. A solenoid valve is provided in the connecting pipe. The moving plate is slidably connected to the inner wall of the chute. A conduit communicates between the first moving groove and the second moving groove. A fixing plate is fixedly connected to the bottom surface of the second connecting plate. A second spring is fixedly connected between the fixing plate and the inner wall of the second storage tank.

[0022] The beneficial effects of this invention are as follows: 1. This invention utilizes a dry electrode preparation method based on unfilled waste positive electrode sheets to achieve high-purity, high-economic stripping, recycling, and reuse, significantly improving the resource utilization efficiency of waste and reducing recycling costs. Simultaneously, relying on the dry electrode process, the invention optimizes process parameters to achieve efficient secondary utilization of the original PVDF binder in the stripping material, reducing the consumption of new materials and simplifying process steps, thereby further reducing production costs.

[0023] 2. This invention fills the gaps between the original cathode material particles and optimizes the material packing density by supplementing small-particle new positive electrode active material with stripped large-particle positive electrode material to form a gradation, thereby constructing an excellent self-supporting film with high stability and improving the mechanical stability and durability of the finished electrode. The dry electrode process replaces the conventional wet process for electrode preparation, overcoming the dependence on solvents in traditional wet processes, as well as the resulting health hazards, high costs, and environmental risks. Attached Figure Description

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] Figure 1 and Figure 2 This is a flowchart of the method in this invention; Figure 3 These are electron microscope images of the dry electrode sheets prepared according to the method of this invention; Figure 4 This is a schematic diagram of the airflow separator in this invention; Figure 5 This is a schematic diagram of the internal structure of the airflow separator in this invention; Figure 6 yes Figure 5 Enlarged view of point A; Figure 7 yes Figure 5 Enlarged view of point B.

[0026] In the diagram: 1. Airflow separator; 2. First feed trough; 3. Feed chamber; 4. Impurity removal chamber; 5. Installation area; 6. Side plate; 7. Discharge trough; 8. Second feed trough; 9. First storage tank; 10. Second storage tank; 11. First discharge port; 12. Second discharge port; 13. Slide chute; 14. Moving plate; 15. Filter screen; 16. Connecting line; 17. First connecting plate; 18. Rotating shaft; 19. Sealing plate; 20. Third feed trough; 21. Fixed plate; 22. Connecting pipe; 23. Second connecting plate; 24. Conduit. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0028] Example 1: As Figures 1 to 2 As shown in the embodiment of the present invention, a method for preparing a dry electrode using a waste positive electrode sheet that has not been injected with liquid includes the following steps: S1: The waste production electrode sheets are pre-treated by the pre-treatment unit. The pre-treatment unit crushes the large-sized electrode sheets with crushing equipment to bring the electrode sheet size into the size range required by the subsequent process. With the help of the screening function in the crushing equipment, materials that do not meet the size requirements are initially separated. S2: The pretreatment unit uses an airflow separator 1 to specifically remove the extremely small-sized electrode sheets generated during the crushing process, as well as foreign matter such as metal scraps and fibers mixed in the raw materials. S3: The electrode sheet after being processed by the pretreatment unit enters the back-end material regeneration unit. The material regeneration unit adopts a low-temperature pyrolysis process. After low-temperature pyrolysis treatment, the positive electrode sheet can be separated into two parts: positive electrode material with its own PVDF and aluminum foil. The aluminum foil can be collected and recycled using the airflow separator 1. S4: The positive electrode material with PVDF obtained after low-temperature pyrolysis will enter the electrode preparation unit for electrode preparation. The electrode preparation unit includes four sequential processes: primary ball milling, secondary ball milling, airflow shearing and hot rolling, to prepare regenerated electrode sheets.

[0029] The steps for using the airflow separator 1 include: A1: The second discharge port 12 is sealed by the moving plate 14, and the sealing plate 19 is sealed to the port of the first storage tank 9. The raw materials processed by the pretreatment unit are fed into the feeding chamber 3 from the first feeding tank 2. After that, the raw materials will pass through the impurity removal area. A2: When the raw materials pass through the impurity removal zone, the gas generated by the air pump blows away the metal scraps, fibers and other foreign objects mixed in with the raw materials. The gas will carry the foreign objects from the second feed trough 8 into the first storage trough 9. A3: The first discharge port 11 is sealed by the moving plate 14, and the sealing plate 19 is sealed to the port of the second storage tank 10. Then, the mixture of positive electrode material and aluminum foil is put into the impurity removal area. At this time, the gas blows the aluminum foil into the second storage tank 10 for storage, to be recycled later.

[0030] The process flow includes three adjacent and sequentially progressive process units: a pretreatment unit, a material regeneration unit, and an electrode preparation unit. The pretreatment unit is the first process unit of the present invention, including two sequentially progressive processes: crushing and impurity removal. Waste production electrode sheets first enter the crushing process in the pretreatment unit to refine large-sized electrode sheets to meet the size requirements of subsequent processes. At the same time, materials of unqualified sizes are initially separated by screening to ensure the size uniformity of materials entering the subsequent processes. The uniformly sized materials obtained after the crushing process enter the impurity removal process in the subsequent process to remove extremely small-sized electrode sheets generated during crushing and foreign matter mixed in with the raw materials, so as to avoid affecting the electrode performance in subsequent processes. The materials after the impurity removal process enter the material regeneration unit in the subsequent process.

[0031] In this embodiment of the invention, the material regeneration unit aims to achieve efficient separation of the positive electrode active material and the current collector in the electrode sheet, while retaining most of the PVDF material in the positive electrode active material, thus saving material addition costs for the downstream electrode preparation unit. This unit employs a low-temperature pyrolysis process, achieving the above objective through optimized pyrolysis conditions (temperature range 150–300°C, pyrolysis time 0.5–1 h) and a protective atmosphere (inert atmosphere, oxygen content not exceeding 50 ppm). After low-temperature pyrolysis, the positive electrode sheet can be separated into two parts: the positive electrode material containing PVDF and aluminum foil. The aluminum foil can be collected and recycled using an airflow separator 1, while the positive electrode material containing PVDF enters the downstream electrode preparation unit for further processing.

[0032] The PVDF-containing cathode material obtained after processing in the material regeneration unit enters the third process unit (electrode preparation unit) of this invention to prepare the regenerated electrode sheet described in this invention. The electrode preparation unit includes four adjacent and sequentially progressive processes: primary ball milling, secondary ball milling, airflow shearing, and hot rolling. The PVDF-containing cathode material first achieves material homogenization during the primary ball milling process, ensuring the material particle size (Dmax≤50μm, D50≤20μm). During the secondary ball milling process, performance is improved by adding auxiliary materials (PTFE, conductive agent, and small-particle cathode active material), while simultaneously achieving homogenization of the cathode material and the auxiliary materials. Among the added auxiliary materials, PTFE can improve electrode adhesion and stabilize component bonding; the conductive agent can construct a conductive network to reduce internal resistance and improve electron conduction efficiency; and the small-particle cathode active material can fill voids, optimize packing density, and thus improve the electrochemical performance of the electrode sheet.

[0033] In this embodiment of the invention, the PVDF-containing cathode material, processed by the material regeneration unit, enters the third process unit (electrode preparation unit) for preparing regenerated electrode sheets. The electrode preparation unit includes four sequential processes: primary ball milling, secondary ball milling, airflow shearing, and hot rolling. The PVDF-containing cathode material is first homogenized by primary ball milling to ensure the particle size (Dmax≤50μm, D50≤20μm); then it enters secondary ball milling, where the performance is improved by adding auxiliary materials (0.5%~3%PTFE, 0.5%~2% conductive agent, 1%~48% small-particle cathode active material; small-particle cathode active material Dmax≤10μm, D50≤μm), and the homogenization of the cathode material and auxiliary materials is achieved. In the auxiliary materials, PTFE can improve electrode adhesion and stabilize component bonding; conductive agents construct a conductive network to reduce internal resistance and improve electron conduction efficiency; small-particle positive electrode active materials fill gaps and optimize packing density, thereby improving the electrochemical performance of the electrode; after secondary ball milling, the material enters the airflow shearing process, where high-speed airflow causes the binder to form a continuous fiber structure, improving the mechanical strength and cycle stability of the electrode and laying the foundation for hot rolling densification. This process uses an airflow velocity of 40-60 m / s, a material residence time of 10-20 min, and a chamber temperature of 60-80℃. Subsequently, the material enters the hot rolling process, where a self-supporting electrode film with a thickness of 250-300 μm can be formed at 150-200℃, a pressure of 5-10 MPa, and a roller speed of 2-3 m / min. Optimized parameters can promote material densification, ensure appropriate melting and distribution of the binder, guarantee the self-support of the film, and avoid damage to the active material, providing a structurally stable and uniformly performing regenerated electrode for battery assembly.

[0034] The following are specific embodiments of a method for preparing dry electrodes using unfilled waste positive electrode sheets, employing the technical solution described in this invention. Figure 3 In a specific embodiment of the present invention, the electron microscopy characterization results of the electrode sheet prepared by the dry electrode preparation method of the present invention clearly show the fibrous structure of the electrode sheet, and the positive electrode materials of different particle sizes in the electrode sheet form a good gradation.

[0035] Table 1 records the performance data of the regenerated electrode sheets and standard electrode sheets prepared by the dry electrode method described in this invention in various specific embodiments of the invention. Experimental results show that the material samples regenerated by the method of this invention still maintain excellent performance.

[0036] Table 1 Performance Data Comparison Table 2 records a comparison of PVDF addition data during the production process of regenerated electrode sheets and standard electrode sheets prepared by the dry method described in this invention in various specific embodiments of the invention.

[0037] Table 2 Comparison of PVDF Dosing Data Example 2: Figures 4 to 7 As shown in the comparative embodiment one, another embodiment of the present invention is: an apparatus for preparing dry electrodes using unfilled waste positive electrode sheets. This apparatus is applicable to the above-mentioned method for preparing dry electrodes. The airflow separator 1 is provided with a feeding chamber 3 and a removal chamber 4. A first feeding groove 2 is opened on the top surface of the airflow separator 1, and a first discharge groove 7 is opened on the bottom surface of the airflow separator 1. An installation area 5 is opened on the side wall of the airflow separator 1. The installation area 5 is used to install an air pump. A side plate 6 is provided in the installation area 5. A set of air outlet holes communicating with the installation area 5 are opened on the inner wall of the removal chamber. The airflow separator 1 has a first storage tank 9 and a second storage tank 10. The inner wall of the impurity removal zone has a second feed trough 8 that communicates with the first storage tank 9. The bottom surface of the airflow separator 1 has a first discharge port 11 that communicates with the first storage tank 9. The bottom surface of the airflow separator 1 also has a second discharge port 12 that communicates with the second storage tank 10. The airflow separator 1 is equipped with a first sealing assembly for sealing the first discharge port 11 and the second discharge port 12. The airflow separator 1 is also equipped with a second sealing assembly for sealing the ports of the first storage tank 9 and the second storage tank 10. When the raw material after the pretreatment unit needs to be processed, this application can use the air pump in the installation area 5 to generate gas, which is then discharged from the air outlet. The raw material is then fed from the first feed trough 2 into the feed chamber 3. Afterwards, the raw material passes through the impurity removal zone, where the gas specifically removes extremely small electrode sheets, metal scraps, fibers, and other foreign matter mixed in with the raw material. The gas carries these impurities into the first storage tank 9 for storage. When discharge is required, the first sealing component can be de-sealed to allow the impurities in the first storage tank 9 to be discharged. The electrode sheets processed by the downstream material regeneration unit can be separated into positive electrode material with built-in PVDF and... When the aluminum foil needs to be separated, the port of the first storage tank 9 is sealed by the second sealing component, while the port of the second storage tank 10 is opened. Then, the mixed aluminum foil and positive electrode material are fed into the feeding area. Because the aluminum foil is lighter than the positive electrode material, when the material passes through the impurity removal area, the gas will carry the aluminum foil from the second feeding tank 8 into the second storage tank 10, so that the aluminum foil can be stored in the second storage tank 10 for subsequent recycling. This application can complete the impurity removal of raw materials and the separation and recycling of aluminum foil through the airflow separator 1, thereby improving the applicability of the airflow separator 1 and improving the efficiency of the entire process.

[0038] The first sealing assembly includes a groove 13 formed on the side wall, the groove 13 communicating with the first discharge port 11 and the second discharge port 12. A movable plate 14 slides within the groove 13, and a through groove is formed on the movable plate 14. A filter screen 15 is fixedly connected to the inner wall of the through groove. When the first discharge port 11 needs to be opened, the movable plate 14 can be moved so that it is completely removed from below the first discharge port 11. At this time, impurities in the first storage cavity can be discharged from the first discharge port 11. When the second discharge port needs to be sealed... When the sealing plate 19 is moved, the groove on the sealing plate 19 is misaligned with the first discharge port 11. At this time, the sealing plate 19 can seal the second discharge port 12. When the aluminum foil enters the second storage tank 10, the sealing plate 19 can be moved so that the filter screen 15 on the sealing plate 19 is located at the second discharge port 12. At this time, the gas can be discharged through the filter screen 15, and the aluminum foil remains in the second storage tank 10. By completely removing the moving plate 14 from under the second discharge port 12, the aluminum foil in the second storage tank 10 can be discharged from the second discharge port 12.

[0039] A first connecting plate 17 is fixedly connected to the side wall of the airflow separator 1. A first movable groove communicating with a slide 13 is formed on the side of the first connecting plate 17 near the airflow separator 1. A rotating shaft 18 is rotatably connected within the first movable groove. A motor driving the rotating shaft 18 is mounted on the first connecting plate 17. A connecting line 16 is fixedly connected to the rotating shaft 18. One end of the connecting line 16 away from the rotating shaft 18 is fixedly connected to a movable plate 14. The other end of the movable plate 14 away from the connecting line 16 is connected to the slide 13. A first spring is fixedly connected between the walls. When the movable plate 14 needs to move, the application can use a motor to control the rotation of the shaft 18, so that the connecting wire 16 is wound around the shaft 18. At this time, the connecting wire 16 can pull the movable plate 14 to move. The number of rotations of the shaft 18 can control the stroke of the connecting plate, thereby adjusting the state of the first discharge port 11 and the second discharge port 12. When the shaft 18 is reversed by the motor, the first spring will pull the movable plate 14 to move away from the shaft 18.

[0040] The second sealing assembly includes a second connecting plate 23 fixed to the side wall of the airflow separator 1. A second moving groove is provided on the side of the airflow separator 1 closest to the airflow separator 1. A sealing plate 19 is slidably connected in the second moving groove. A third feeding groove 20 is provided on the sealing plate 19. A connecting pipe 22 communicating with the second feeding groove 8 is provided on the second connecting plate 23. A solenoid valve is provided in the connecting pipe 22. The moving plate 14 is slidably connected to the inner wall of the sliding groove 13. A conduit 24 communicates between the first moving groove and the second moving groove. A fixing plate 21 is fixedly connected to the bottom surface of the second connecting plate 23. A second spring is fixedly connected between the fixing plate 21 and the inner wall of the second storage tank 10. When the second storage tank 10 needs to be used, the moving plate 14 is pulled by the connecting line 16, so that the filter screen 15 on the moving plate 14 moves to below the second discharge port 12. At the same time, the moving plate 14 can seal the first discharge port 11. When the moving plate 14 moves, it can push the gas in the first moving tank into the second moving tank through the conduit 24. At this time, the gas will push the sealing plate 19, so that the sealing plate 19 seals the port of the first storage tank 9. The second feed trough 8 will be located at the port of the second storage tank 10. At this time, the separated aluminum foil can enter the storage tank from the second feed trough 8. When it is necessary to seal the port of the second storage tank 10, the solenoid valve can be opened. At this time, the second spring will push the fixing plate 21, so that the fixing plate 21 drives the sealing plate 19 to reset, so that the sealing plate 19 seals the port of the second storage tank 10. The gas in the second moving tank can be discharged from the connecting pipe 22.

[0041] Working principle: Waste production electrode sheets are pre-treated by the pre-treatment unit. The pre-treatment unit crushes large-sized electrode sheets with crushing equipment to bring the electrode sheet size into the size range required by subsequent processes. With the help of the screening function in the crushing equipment, materials that do not meet the size requirements are initially separated. Raw materials are fed into the feeding chamber 3 from the first feeding trough 2. The raw materials then pass through a purification zone, where gas specifically removes extremely small electrode sheets, metal scraps, fibers, and other foreign matter mixed in with the raw materials. The gas carries these impurities into the first storage tank 9 for storage. When discharge is required, the first sealing assembly can be de-sealed to allow the impurities in the first storage tank 9 to be discharged. After processing by the downstream material regeneration unit, the electrode sheets can be separated into two parts: a positive electrode material with built-in PVDF and aluminum foil. When the aluminum foil needs to be separated, it is separated by the second sealing assembly. The port of the first storage tank 9 is sealed, while the port of the second storage tank 10 is opened. Then, the mixed aluminum foil and positive electrode material are fed into the feeding area. Because the aluminum foil is lighter than the positive electrode material, when the material passes through the impurity removal area, the gas will carry the aluminum foil from the second feeding tank 8 into the second storage tank 10, so that the aluminum foil can be stored in the second storage tank 10 for subsequent recycling. This application can complete the impurity removal of raw materials through the airflow separator 1, and can also separate and recycle aluminum foil, thereby improving the applicability of the airflow separator 1 and improving the efficiency of the entire process. When the first discharge port 11 needs to be opened, the moving plate 14 can be moved so that the moving plate 14 is completely removed from below the first discharge port 11. At this time, impurities in the first storage chamber can be discharged from the first discharge port 11. When the second discharge port needs to be sealed, the sealing plate 19 can be moved so that the through groove on the sealing plate 19 is misaligned with the first discharge port 11. At this time, the sealing plate 19 can seal the second discharge port 12. When the aluminum foil enters the second storage tank 10, the sealing plate 19 can be moved so that the filter screen 15 on the sealing plate 19 is located at the second discharge port 12. At this time, the gas can be discharged through the filter screen 15, and the aluminum foil remains in the second storage tank 10. By completely removing the moving plate 14 from below the second discharge port 12, the aluminum foil in the second storage tank 10 can be discharged from the second discharge port 12. When the movable plate 14 needs to be moved, the motor controls the rotating shaft 18 to rotate, allowing the connecting wire 16 to wind around the rotating shaft 18. The connecting wire 16 then pulls the movable plate 14 to move. The number of rotations of the rotating shaft 18 controls the travel of the connecting plate, thereby adjusting the state of the first discharge port 11 and the second discharge port 12. When the motor controls the rotating shaft 18 to reverse, the first spring pulls the movable plate 14 to move away from the rotating shaft 18. When the second storage tank 10 needs to be used, the connecting wire 16 pulls the movable plate 14, causing the filter screen 15 on the movable plate 14 to move below the second discharge port 12. Simultaneously, the movable plate 14 can move the first discharge port 11... When the moving plate 14 moves, it can push the gas in the first moving groove into the second moving groove through the conduit 24. At this time, the gas will push the sealing plate 19, so that the sealing plate 19 seals the port of the first storage groove 9. The second feed groove 8 will be located at the port of the second storage groove 10. At this time, the separated aluminum foil can enter the storage groove from the second feed groove 8. When it is necessary to seal the port of the second storage groove 10, the solenoid valve can be opened. At this time, the second spring will push the fixed plate 21, so that the fixed plate 21 drives the sealing plate 19 to reset, so that the sealing plate 19 seals the port of the second storage groove 10. The gas in the second moving groove can be discharged from the connecting pipe 22.

[0042] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0043] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., 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 limiting the scope of protection of this invention.

[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a dry electrode using unfilled waste positive electrode sheets; characterized in that: Includes the following steps: S1: The waste production electrode sheets are pre-treated by the pre-treatment unit. The pre-treatment unit crushes the large-sized electrode sheets with crushing equipment to make the electrode sheet size reach the size range required by the subsequent process. With the help of the screening function in the crushing equipment, the materials that do not meet the size requirements are initially separated. S2: The pretreatment unit uses an airflow separator (1) to specifically remove the extremely small-sized electrode sheets generated during the crushing process and the metal scraps mixed in the raw materials. S3: The electrode sheet after being processed by the pretreatment unit enters the back-end material regeneration unit. The material regeneration unit adopts a low-temperature pyrolysis process. After low-temperature pyrolysis, the positive electrode sheet is separated into two parts: positive electrode material with its own PVDF and aluminum foil. The aluminum foil is collected and recycled using an airflow separator (1). S4: The positive electrode material with PVDF obtained after low-temperature pyrolysis will enter the electrode preparation unit for electrode preparation. The electrode preparation unit includes four sequential processes: primary ball milling, secondary ball milling, airflow shearing and hot rolling, to prepare regenerated electrode sheets.

2. The method for preparing a dry electrode using unfilled waste positive electrode sheet according to claim 1, characterized in that: The steps for using the airflow separator (1) include: A1: The second discharge port (12) is sealed by the moving plate (14), and the sealing plate (19) is sealed to the port of the first storage tank (9). The raw material processed by the pretreatment unit is fed from the first feed tank (2) into the feed chamber (3), and then the raw material will pass through the impurity removal area. A2: When the raw materials pass through the impurity removal zone, the gas generated by the air pump blows away the metal scraps, fibers and other foreign objects mixed in the raw materials. The gas will carry the foreign objects from the second feed tank (8) into the first storage tank (9). A3: The first discharge port (11) is sealed by the moving plate (14), and the sealing plate (19) is sealed to the port of the second storage tank (10). Then the mixture of positive electrode material and aluminum foil is put into the impurity removal area. At this time, the gas blows the aluminum foil into the second storage tank (10) for storage, to be recycled later.

3. The method for preparing a dry electrode by using a waste cathode sheet without liquid injection according to claim 1, characterized in that: The electrode sheet is crushed to a size of 200–1000 mm. The low-temperature pyrolysis temperature range is 150–300 °C, and the pyrolysis time is 0.5–1 h. The first ball milling process takes 0.5–12 h. After the first ball milling process, the particle size of the material meets the requirements of Dmax ≤ 50 μm and D50 ≤ 20 μm. The second ball milling process takes 0.5–6 h.

4. The method for preparing a dry electrode using a non-liquid-impregnated waste cathode sheet according to claim 1, characterized by: The auxiliary materials added in the secondary ball milling process are: PTFE, conductive agent, and new positive electrode active material. The PTFE is a high molecular weight fluoropolymer, the conductive agent is a material with excellent conductivity, the dosage of the PTFE auxiliary material is 0.5% to 3%, the dosage of the conductive agent is 0.5% to 2%, and the dosage of the new positive electrode active material is 1% to 48%, with Dmax ≤ 10 μm and D50 ≤ 1.18 μm.

5. The method and device for preparing dry electrodes using un-liquid injected waste positive electrode sheets according to claim 1, characterized in that: The airflow shearing process uses a high-speed airflow with a velocity of 40-60 m / s to form a shearing force field. The residence time of the material in the shearing chamber is controlled to be 10-20 min, while the temperature inside the chamber is maintained at 60-80℃.

6. The method for preparing a dry electrode with a non-liquid-impregnated waste cathode sheet according to claim 1, characterized in that: The hot rolling process is carried out at 150-200°C, while the rolling pressure is controlled at 5-10 MPa and the roller linear speed is controlled at 2-3 m / min. A self-supporting electrode film with a thickness of 250-300 μm is formed by precisely adjusting the roller spacing.

7. An apparatus for preparing a dry electrode using a liquid- un- injected waste cathode sheet, the apparatus being adapted to the method of preparing a dry electrode according to any one of claims 1 to 6, characterized in that: The airflow separator (1) is provided with a feeding chamber (3) and a cleaning chamber (4). A first feeding trough (2) is provided on the top surface of the airflow separator (1), and a first discharge trough (7) is provided on the bottom surface of the airflow separator (1). An installation area (5) is provided on the side wall of the airflow separator (1). The installation area (5) is used to install an air pump. A side plate (6) is provided in the installation area (5). A set of air outlet holes communicating with the installation area (5) are provided on the inner wall of the cleaning chamber. A first storage tank (9) and a second storage tank (10) are provided in the airflow separator (1). The inner wall is provided with a second feed trough (8) communicating with the first storage tank (9). The bottom surface of the airflow separator (1) is provided with a first discharge port (11) communicating with the first storage tank (9). The bottom surface of the airflow separator (1) is also provided with a second discharge port (12) communicating with the second storage tank (10). The airflow separator (1) is provided with a first sealing component to seal the first discharge port (11) and the second discharge port (12). The airflow separator (1) is provided with a second sealing component to seal the ports of the first storage tank (9) and the second storage tank (10).

8. The device for preparing a dry electrode using a non-liquid-impregnated waste positive electrode sheet according to claim 7, characterized by: The first sealing assembly includes a slid groove (13) formed on the side wall. The slid groove (13) is connected to the first discharge port (11) and the second discharge port (12). A movable plate (14) slides in the slid groove (13). A through groove is formed on the movable plate (14). A filter screen (15) is fixedly connected to the inner wall of the through groove.

9. The apparatus for preparing a dry electrode using unfilled waste positive electrode sheet according to claim 8, characterized in that: The airflow separator (1) is fixedly connected to a first connecting plate (17) on its side wall. The first connecting plate (17) has a first moving groove connected to the slide groove (13) on the side near the airflow separator (1). A rotating shaft (18) is rotatably connected in the first moving groove. A motor for driving the rotating shaft (18) is provided on the first connecting plate (17). A connecting line (16) is fixedly connected to the rotating shaft (18). The end of the connecting line (16) away from the rotating shaft (18) is fixedly connected to the moving plate (14). The end of the moving plate (14) away from the connecting line (16) is fixedly connected to the inner wall of the slide groove (13) with a first spring.

10. The apparatus for preparing a dry electrode using unfilled waste positive electrode sheet according to claim 9, characterized in that: The second sealing assembly includes a second connecting plate (23) fixed to the side wall of the air classifier (1). A second moving groove is provided on the side of the air classifier (1) near the air classifier (1). A sealing plate (19) is slidably connected in the second moving groove. A third feeding groove (20) is provided on the sealing plate (19). A connecting pipe (22) communicating with the second feeding groove (8) is provided on the second connecting plate (23). A solenoid valve is provided in the connecting pipe (22). The moving plate (14) is slidably connected to the inner wall of the sliding groove (13). A conduit (24) is connected between the first moving groove and the second moving groove. A fixing plate (21) is fixedly connected to the bottom surface of the second connecting plate (23). A second spring is fixedly connected between the fixing plate (21) and the inner wall of the second storage tank (10).

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