Method for recycling materials from spent lithium-ion batteries

Abstract

The application provides a recycling method of lithium ion battery material, comprising the following steps: a pretreatment step: discharging and crushing a lithium ion battery to obtain a crushed product; an alcoholysis step: providing a reaction kettle, adding a liquid alcoholysis agent and the crushed material into the reaction kettle, adjusting the temperature in the reaction kettle to 90-300 DEG C, making the alcoholysis agent in the reaction kettle in a supercritical state or a subcritical state, and the temperature in the reaction kettle being 90-300 DEG C, the alcoholysis agent and the crushed material generating an alcoholysis reaction to obtain an alcoholysis product; a post-treatment step; and separating the alcoholysis product to obtain black powder, stainless steel, copper and aluminum. The application realizes the separation of organic matters in the lithium ion battery through the alcoholysis reaction and the control of the alcoholysis temperature, and also makes the aluminum material in the lithium ion battery not easy to be denatured and embrittled, maintains the integrity of the aluminum, is beneficial to the recycling of the aluminum material and reduces the aluminum content in the black powder, and improves the quality of the black powder.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery recycling technology, specifically a method for recycling waste lithium-ion battery materials. Background Technology

[0002] Lithium-ion batteries (lithium batteries) have advantages such as light weight, small size, high energy density, high operating voltage, low self-discharge, no memory effect, wide operating temperature range, fast charging and discharging, long service life, and environmental friendliness. In recent years, with the increasing maturity of lithium-ion battery technology and industry, they have been widely used in power batteries, consumer electronics, energy storage and other fields, and are gradually replacing lead-acid batteries and nickel-metal hydride batteries.

[0003] Nickel and cobalt are scarce resources among the raw materials for lithium-ion batteries, while lithium reserves are relatively abundant. Currently, there is strong demand for metals related to new energy, but resources are relatively scarce. The lifespan of consumer batteries is generally 3 to 5 years, that of power batteries is generally 5 to 6 years, and that of energy storage batteries is generally 6 to 8 years. Lithium-ion batteries are now entering their large-scale retirement and scrapping phase, making the recycling of lithium-ion batteries an urgent matter. The recycling of used lithium-ion batteries plays a crucial role in alleviating raw material shortages and environmental problems. Recycled metals, as an important supplement to primary ore metals, are a significant source of raw materials for lithium-ion batteries.

[0004] Currently, the mainstream recycling process for spent lithium-ion batteries combines thermal treatment and wet processing. The wet process requires thermal treatment to remove organic impurities such as binders, organic solvents, separators, and plastic casings, yielding a mixed powder of positive and negative electrode materials, known as black powder. However, thermal treatment causes the aluminum foil to deform and become brittle, resulting in a high aluminum content in the black powder product, which is difficult to separate in subsequent steps, hindering the downstream wet recycling process. Summary of the Invention

[0005] To address the above problems, this invention provides a method for recycling lithium-ion battery materials. By controlling the alcoholysis reaction and the alcoholysis temperature, the method achieves efficient removal of organic impurities such as binders, organic solvents, separators, and plastic shells from lithium-ion batteries. It also makes the aluminum material in lithium-ion batteries less prone to deformation and embrittlement, maintaining the integrity of the aluminum material, which is beneficial for aluminum recycling and reduces the aluminum content in the black powder, thereby improving the quality of the black powder.

[0006] This invention provides a method for recycling lithium-ion battery materials, comprising the following steps:

[0007] Pretreatment steps: Discharge and crush the lithium-ion battery to obtain crushed products;

[0008] Alcohololysis step: Provide a reaction vessel and add liquid alcohololysis agent and crushed material into the reaction vessel. Adjust the temperature inside the reaction vessel to 90-300℃ so that the alcohololysis agent inside the reaction vessel is in a supercritical or subcritical state. The alcohololysis agent and the crushed material undergo an alcohololysis reaction to obtain alcohololysis products.

[0009] Post-processing steps: Separate the alcoholysis products to obtain black powder, stainless steel, copper and aluminum.

[0010] According to this technical solution, the subcritical / supercritical alcoholysis agent fluid possesses both liquid and gas properties, and there is no interphase effect (when the fluid reaches the supercritical state, the gas-liquid interface completely disappears and diffuses into a homogeneous phase, and the surface tension drops to 0 near the critical point. Therefore, using supercritical fluid as a solvent can greatly eliminate the mass transfer resistance at the phase interface and significantly improve the reaction rate).

[0011] In supercritical or subcritical states, alcoholysis agents, as polar solvents, possess excellent solubility and mass transfer properties (high diffusion coefficient, low viscosity). They can effectively dissolve substances with relatively large molecular weights, lower the reaction temperature required for polymer depolymerization, shorten the depolymerization time, and can also participate in the reaction as a reactant. By adding the above-mentioned crushed products and alcoholysis agents to a reactor and controlling the temperature at 90-300℃, subcritical / supercritical alcoholysis agent fluids under different temperature conditions can be obtained. These subcritical / supercritical fluids can dissolve organic matter (binders, plastic shells, separators, electrolytes, etc.) in the crushed products and undergo alcoholysis reactions with the organic matter in the crushed products, decomposing or degrading the organic matter in lithium-ion batteries. The resulting alcoholysis products mainly consist of solid products containing positive and negative electrode materials (black powder), stainless steel shells, current collectors, and waste liquid containing organic matter. The organic compounds such as alkanes and olefins (e.g., methane, ethane, propylene, n-butane, isobutane, n-butene, isobutene) generated during alcoholysis can be passed into a hot blast furnace for combustion treatment.

[0012] By controlling the alcoholysis reaction and its temperature, organic matter in lithium-ion batteries is separated. This process also prevents the aluminum in the batteries from becoming brittle and deformed, maintaining the integrity of the aluminum, which is beneficial for aluminum recycling and reduces the aluminum content in the black powder, thus improving the quality of the black powder. Furthermore, the lithium-ion batteries are pre-treated before being discharged and crushed, ensuring the safety of the crushing process and facilitating the separation of organic matter from other materials in subsequent steps. The post-processing steps allow for the separation of the desired products as needed.

[0013] In the optional technical solution of the present invention, in the alcoholysis step, the alcoholysis agent is methanol, the liquid-solid ratio of the alcoholysis agent to the crushed material is 1ml:1g to 10ml:1g, the temperature in the reaction vessel is 180-250℃, and the reaction time of the alcoholysis reaction is 10-30min.

[0014] According to this technical solution, methanol, as the alcoholysis agent, has a critical temperature of 240℃. By controlling the temperature inside the reactor at 180-250℃, methanol can be placed in a subcritical / supercritical state, exhibiting excellent solubility and a low reaction temperature. This not only removes organic matter from the crushed products but also prevents the aluminum in the crushed products from oxidizing and becoming embrittled under high-temperature conditions, maintaining the integrity of the aluminum material. This facilitates aluminum recycling, increases the aluminum recovery rate, and enables resource reuse. Furthermore, by controlling the reaction time, both the full reaction of organic matter and the recovery efficiency can be considered. By selecting an appropriate liquid-solid ratio, the reaction of plastics, diaphragms, binders, and other materials in the crushed material with the alcoholysis agent can be promoted, removing these components while also saving on the amount of alcoholysis agent used and reducing recycling costs.

[0015] In an optional technical solution of the present invention, the post-processing step includes:

[0016] Shaking separation step: Provide a shaking separator, which includes a screen with a mesh size of 60 to 200; put the alcoholysis product into the screen and shake the alcoholysis product on the screen to obtain a mixed coarse material located above the screen;

[0017] Drying step: Provide a drying device, add the mixed coarse material to the drying device and dry the mixed coarse material;

[0018] Multi-stage screening steps: A vibrating screen is provided to transport the dried mixture to the vibrating screen for multi-stage screening. The mesh size of the vibrating screen is 60 mesh to 200 mesh. The screening results in oversize material and undersize material. The oversize material is a mixed metal material including stainless steel, copper and aluminum, and the undersize material is black powder.

[0019] According to this technical solution, the alcoholysis products can be partially removed by shaking separation; further drying can basically completely remove the alcoholysis agent and obtain a dry mixed coarse material. The mixed coarse material is then subjected to multi-stage sieving to obtain a mixture of black powder and metal (stainless steel, copper foil, and aluminum foil, where the stainless steel shell, copper foil, and aluminum foil may be in flake or granular form depending on the degree of crushing). Drying to obtain a relatively dry mixed coarse material can avoid the difficulty of separation between materials due to the presence of solvent and waste liquid, thereby improving the recovery rate of black powder. By controlling the mesh size of the screen in the shaking separator and the screen mesh size in the multi-stage sieving steps to be between 60 and 200 mesh, it is beneficial to obtain a higher content of black powder through shaking and multi-stage sieving, while reducing the content of other materials in the black powder, thereby improving the recovery rate and grade of black powder. The black powder product obtained through this technical solution has a particle size of less than 3μm for more than 95% of the black powder and an aluminum content of less than 1%. The black powder has high purity and small particle size, and can be directly sold as a product with high economic value.

[0020] This technical solution achieves the recovery of black powder and other materials from lithium-ion batteries through processes such as pretreatment, alcoholysis, shaking separation, drying, and multi-stage sieving. It simplifies the process, improves the recovery efficiency, and increases the recovery rate and grade of black powder.

[0021] In the optional technical solution of the present invention, the recovery method further includes an alcoholysis agent recovery step: in the shaking separation step, the alcoholysis product on the screen is shaken to obtain a waste liquid containing a certain amount of black powder located below the screen; a preheater and a recovery tower are provided, the inlet of the preheater is connected to the drying device, the outlet of the preheater is connected to the recovery tower, the preheater is used to heat the waste liquid, the alcoholysis agent escapes from the waste liquid when heated, the recovery tower is used to cool the gaseous alcoholysis agent that escapes from the waste liquid when heated, and the temperature inside the recovery tower is 90-110℃;

[0022] In the drying step, the drying temperature is 90-110℃ and the drying time is 10-15min. During the drying process, the mixed coarse material releases gaseous alcoholysis agent, which is then condensed and recovered.

[0023] According to this technical solution, the waste liquid contains a certain amount of alcoholysis agent. Preheating the waste liquid allows the alcoholysis agent to escape. The escaped gaseous alcoholysis agent is then cooled and recovered in a recovery tower for reuse, reducing the recycling cost of waste lithium-ion battery materials. Alternatively, the liquid alcoholysis agent escapes in gaseous form during the drying of the mixed coarse materials, eliminating the need for repeated heating. Cooling the gaseous agent allows for its recovery and reuse. By controlling the drying time and temperature, both drying efficiency and quality can be balanced, resulting in a relatively dry mixed coarse material in a shorter time. This avoids separation difficulties due to the presence of solvents and waste liquid, improving the recovery rate of black powder. This technical solution can recover alcoholysis agents produced in different processes, improving the recovery rate and contributing to resource conservation.

[0024] In an optional technical solution of the present invention, the oscillation separation step further includes changing the mesh size of the sieve according to the particle size of the black powder.

[0025] According to this technical solution, the mesh size of the screen is increased and the aperture is reduced. By adjusting the aperture of the screen to be smaller than the particle size of the black powder, more black powder can be retained above the screen, thereby reducing the content of black powder in the waste liquid below the screen, improving the recovery rate of black powder, and improving the utilization rate of resources.

[0026] In the optional technical solution of the present invention, the pretreatment step includes: a discharge step: disassembling the lithium-ion battery to obtain lithium battery cells, immersing the lithium battery cells in an aqueous solution for 24-48 hours for discharge, and then draining the discharged lithium battery cells, wherein the aqueous solution is an aqueous solution of sodium chloride, potassium chloride or sodium sulfate with a mass fraction of 5-10 wt%; and a crushing step: crushing the drained lithium battery cells to obtain crushed products.

[0027] According to this technical solution, the lithium battery cells are discharged by immersing them in an aqueous solution, which has the advantages of simple operation, suitability for batch processing, and high efficiency. By discharging the lithium battery cells before crushing them, the safety of crushing can be improved, and deflagration and explosion can be prevented during the crushing process.

[0028] In an optional technical solution of the present invention, during the crushing step, the lithium battery cell is placed into the crushing chamber of the crusher for crushing, and inert gas is introduced into the crushing chamber to maintain a nitrogen atmosphere and a negative pressure environment in the crushing chamber.

[0029] According to this technical solution, by filling the crushing chamber with inert gas and maintaining an inert atmosphere and negative pressure environment inside the crushing chamber, the explosion of lithium battery cells can be prevented, thereby improving the safety of the crushing process.

[0030] In the optional technical solution of the present invention, in the crushing step, the width of the crushed material is ≤20mm and the length of the crushed material is ≤20mm.

[0031] According to this technical solution, by controlling the length and width of the crushed material within a certain range, that is, the crushed product is in the form of large pieces, it is possible to avoid the final black powder containing a large amount of copper and aluminum, thereby improving the purity and grade of the black powder.

[0032] In an optional technical solution of the present invention, a metal magnetic separation step is also included: providing a magnetic separator to separate the mixed metal materials using the magnetic separator, so that the magnetic stainless steel is separated from the non-magnetic aluminum and copper, and stainless steel products and copper and aluminum mixture are obtained.

[0033] According to this technical solution, a magnetic separator is used to separate magnetic and non-magnetic substances from mixed metal materials. The process is simple and easy to operate.

[0034] In an optional technical solution of the present invention, an eddy current separation step is also included: providing an eddy current separator to separate the copper and aluminum mixture, thereby separating the copper and aluminum.

[0035] According to this technical solution, the use of an eddy current separator for sorting has the advantages of high sorting efficiency, large processing capacity, strong adaptability, and excellent sorting effect, and can obtain relatively pure aluminum and copper products. Attached Figure Description

[0036] Figure 1 This is a schematic flowchart of a method for recycling waste lithium-ion battery materials according to an embodiment of the present invention.

[0037] Figure 2 This is a flowchart illustrating the post-processing steps in an embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention provides a method for recycling waste lithium-ion battery materials, applicable to most lithium-ion batteries, such as lithium iron phosphate and ternary lithium batteries. The lithium-ion battery includes a casing, a positive electrode, a separator, a negative electrode, a current collector (copper foil, aluminum foil), an electrolyte, and a binder (used to bond the positive and negative electrode active materials to the current collector). The casing includes steel casings, aluminum casings, plastic casings, nickel-plated iron casings, and soft-pack (aluminum-plastic film). The separator is a plastic film that allows lithium ions to pass through but is an insulator for electrons. Currently, the main types are polyethylene (PE) and polypropylene (PP), as well as multilayer microporous membranes composed of PE and PP. Another type of inorganic solid membrane, such as alumina membrane coating, is an inorganic solid membrane. The electrolyte is an organic system composed of lithium salt (lithium hexafluorophosphate, both solid and liquid salts), solvent (cyclic and chain-like, such as EC, DMC, EMC, etc.), and additives (such as flame retardant additives, film-forming additives, etc.). Commonly used binders include polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), and N-methylpyrrolidone (NMP). In addition, there are water-based binders with polyacrylic acid (PAA), polyacrylonitrile (PAN), and polyacrylate as the main components.

[0040] Specifically, such as Figure 1 As shown, in this embodiment, the method for recycling lithium-ion battery materials includes the following steps:

[0041] Pretreatment steps: The lithium-ion battery is discharged and crushed to obtain crushed products; among which,

[0042] In the discharge step, the lithium-ion battery is disassembled to obtain the lithium battery cell. The lithium battery cell is immersed in an aqueous solution for 24-48 hours for discharge. Then the discharged lithium battery cell is drained. The aqueous solution is an aqueous solution of sodium chloride, potassium chloride or sodium sulfate with a mass fraction of 5-10 wt%.

[0043] In the crushing step, the drained lithium battery cells are crushed to obtain crushed products. Discharging the lithium battery cells by immersing them in an aqueous solution offers advantages such as simplicity, suitability for batch processing, and high efficiency. Discharging the lithium-ion cells before crushing improves safety and prevents deflagration or explosion during the crushing process. The crushed products are lithium-ion battery cells, which contain positive and negative electrode materials, plastic casings, metal casings, current collectors, separators, electrolytes (including lithium salts, organic solvents, and various additives), and organic binders. Crushing the battery into smaller components facilitates subsequent reactions. Furthermore, the crushing process involves crushing the plastic and metal casings along with the battery cells, eliminating the need for manual removal and improving crushing efficiency. The casings can also be decomposed together in subsequent reactions.

[0044] In a preferred embodiment of the present invention, in the crushing step, a crusher is provided, the crusher having a crushing chamber. The lithium battery cell is placed into the crushing chamber of the crusher for crushing, and an inert gas is introduced into the crushing chamber to maintain a nitrogen atmosphere and a negative pressure environment. By introducing an inert gas into the crushing chamber and maintaining an inert atmosphere and negative pressure environment within the crushing chamber, the explosion of the lithium battery cell can be prevented, improving the safety of the crushing process. Furthermore, the crushing chamber is sealed during the crushing process.

[0045] In a preferred embodiment of the present invention, during the crushing step, the width of the crushed material is ≤20mm and the length of the crushed material is ≤20mm. By controlling the length and width of the crushed material within a certain range, i.e., the crushed product is in large flake form, it is possible to avoid the final black powder containing a large amount of copper and aluminum, thereby improving the purity and grade of the black powder.

[0046] Furthermore, in this embodiment, the recycling method also includes:

[0047] Alcohololysis step: Provide a reaction vessel and add alcoholysis agent (liquid) and crushed material into the reaction vessel. Adjust the temperature inside the reaction vessel to 90-300℃. The alcoholysis agent and the crushed material undergo an alcoholysis reaction to obtain alcoholysis products.

[0048] Post-processing steps: Separate the alcoholysis products to obtain black powder, stainless steel, copper and aluminum.

[0049] Specifically, the alcoholysis agent is methanol, ethanol, propanol, butanol, ethylene glycol, etc. In this embodiment, methanol is used as the alcoholysis agent. The alcoholysis reaction is a decomposition or degradation reaction of compounds under the action of alcohol. The above-mentioned crushed products and alcoholysis agent are added to a reaction vessel, and the temperature is controlled at 150-300℃ to obtain subcritical or supercritical methanol fluids under different temperature conditions. This subcritical / supercritical fluid can dissolve organic matter (binder, plastic shell, diaphragm, electrolyte, etc.) in the crushed products and undergo alcoholysis reaction with the organic matter in the crushed products, thereby rapidly removing the organic matter (binder, plastic shell, diaphragm, electrolyte, etc.) and obtaining an alcoholysis product containing positive and negative electrode materials, a stainless steel shell, a current collector, and the alcoholysis agent. The peeling rate of the positive and negative electrode materials reaches over 99%. The organic compounds generated during the process, such as alkanes and olefins (e.g., methane, ethane, propylene, n-butane, isobutane, n-butene, isobutene), can be combusted in a hot blast furnace. The removal of organic matter from the battery cell via alcoholysis lowers the reaction temperature, increases the removal efficiency, simplifies the removal process, and reduces the difficulty of removal, thus improving recovery efficiency. Furthermore, compared to traditional pyrolysis, alcoholysis occurs at a lower temperature, at which aluminum foil is less prone to denaturation and embrittlement, facilitating aluminum foil recycling and reducing the aluminum foil content in the black powder, thereby improving the black powder grade. Additionally, supercritical methanol has a low critical temperature (Tc) and critical pressure (Pc) of 239.4℃ and 8.092 MPa, respectively, indicating low temperature and pressure, low corrosiveness, and friendliness to metal equipment. Methanol has a low boiling point (64.7℃), requiring only a lower heating temperature for product separation and purification, facilitating methanol reuse. Supercritical methanol can also replace currently used toxic and harmful methylation reagents, simplifying experimental procedures.

[0050] In a preferred embodiment of the present invention, the alcoholysis step is carried out at a temperature of 180-250°C for a reaction time of 10-30 minutes. By controlling the alcoholysis temperature at 180-250°C and the reaction time at 10-30 minutes, the oxidation and embrittlement of aluminum in the crushed products under high-temperature conditions can be prevented, maintaining the integrity of the aluminum foil, thereby facilitating aluminum foil recycling, increasing the aluminum foil recovery rate, and realizing resource reuse. Furthermore, by controlling the reaction time, both the full reaction of organic matter and the recycling efficiency can be considered. Further, in the alcoholysis step, the liquid-to-solid ratio of the alcoholysis agent to the crushed material is 1 ml:1 g to 10 ml:1 g. Choosing a suitable liquid-to-solid ratio can promote the full reaction of materials such as plastics, diaphragms, and binders in the crushed material with the alcoholysis agent, removing components such as plastics, diaphragms, and binders from the crushed material, while also saving the amount of alcoholysis agent used and reducing recycling costs.

[0051] Preferably, such as Figure 2 As shown, the post-processing steps include:

[0052] Shaking separation step: Provide a shaking separator, which includes a screen with a mesh size of 60 to 200; put the alcoholysis product into the screen and shake the alcoholysis product on the screen to obtain a mixed coarse material located above the screen;

[0053] Drying steps: Provide a drying device, add the mixed coarse material to the drying device and dry the mixed coarse material. The drying temperature is 90-110℃ and the drying time is 10-15 minutes.

[0054] Multi-stage screening process: A vibrating screen is provided to transport the dried mixture to the vibrating screen for multi-stage screening. The mesh size of the vibrating screen is 60 to 200 mesh. The screening results in oversize and undersize materials. The oversize material is a mixed metal material including stainless steel, copper and aluminum.

[0055] The alcoholysis products can be partially removed by shaking separation. Further drying can almost completely remove the alcoholysis agent and obtain a dry mixed coarse material. The mixed coarse material is then screened in multiple stages to obtain a mixture of black powder and metal (stainless steel, copper foil, and aluminum foil). By controlling the drying time and temperature, both drying efficiency and drying quality can be achieved, and a relatively dry mixed coarse material can be obtained in a shorter time. This avoids separation difficulties between materials due to the presence of solvents and waste liquid, and improves the recovery rate of black powder. By controlling the mesh size of the screen in the shaking separator and the screen size in the multi-stage screening step to be between 60 and 200 mesh, it is beneficial to obtain a higher content of black powder through shaking and multi-stage screening, and reduce the content of other materials in the black powder, thereby improving the recovery rate and grade of black powder. In this embodiment, more than 95% of the black powder has a particle size of less than 3 μm and an aluminum content of less than 1%. The black powder has high purity and small particle size, which is close to the particle size of the primary single crystal spheres of the original positive and negative electrode materials. It can be sold directly as a product and has high economic value.

[0056] In a preferred embodiment of the present invention, during the shaking separation step, the mesh size of the sieve is adjusted and replaced according to the particle size of the black powder to reduce the black powder content in the waste liquid. Increasing the mesh size of the sieve reduces the pore size. By adjusting the pore size of the sieve to be smaller than the particle size of the black powder, more black powder can be retained above the sieve, thereby reducing the black powder content in the waste liquid below the sieve, improving the black powder recovery rate, and increasing resource utilization.

[0057] In a preferred embodiment of the present invention, the recovery method further includes an alcoholysis agent recovery step:

[0058] In the shaking separation step, the alcoholysis product on the screen is shaken to obtain a waste liquid containing a certain amount of black powder located below the screen. A preheater and a recovery tower are provided. The inlet of the preheater is connected to the drying device, and the outlet of the preheater is connected to the recovery tower. The preheater is used to heat the waste liquid, and the alcoholysis agent escapes during the heating process. The recovery tower is used to cool the gaseous alcoholysis agent that escapes during the heating process. The temperature inside the recovery tower is 90-110°C. Since the waste liquid contains a certain amount of alcoholysis agent, preheating the waste liquid can cause the alcoholysis agent in the waste liquid to escape. The escaped gaseous alcoholysis agent is cooled and recovered by the recovery tower and can be reused, reducing the recycling cost of waste lithium-ion battery materials. The preheating temperature, preheating time, and condensation time of the alcoholysis agent in the recovery tower can be designed according to different parameters such as the waste liquid treatment volume. This embodiment does not limit these parameters.

[0059] In the drying step, gaseous alcoholysis agent escapes from the mixed coarse materials during drying. This gaseous alcoholysis agent is condensed and recovered. Liquid alcoholysis agent escapes in gaseous form during the drying of the mixed coarse materials, eliminating the need for repeated heating; it can be recovered and reused simply by cooling. This technical solution can recover alcoholysis agents produced in different processes, improving the recovery rate and contributing to resource conservation.

[0060] In a preferred embodiment of the present invention, a metal magnetic separation step is further included: a magnetic separator is provided to separate the mixed metal materials, thereby separating the magnetic stainless steel from the non-magnetic aluminum and copper, to obtain stainless steel products and a mixture of copper and aluminum. Using a magnetic separator to separate magnetic and non-magnetic substances from the mixed metal materials is a simple and convenient process.

[0061] In a preferred embodiment of the present invention, an eddy current separation step is further included: providing an eddy current separator to separate the copper and aluminum mixture, thereby obtaining pure aluminum and copper products. Using an eddy current separator offers advantages such as high separation efficiency, large processing capacity, strong adaptability, and excellent separation effect. Furthermore, by selecting a suitable eddy current separator, not only can copper and aluminum be efficiently separated, but also copper and aluminum particles with a diameter greater than 0.2 mm can be separated, improving the recovery rate of copper and aluminum, saving resources, facilitating resource reuse, and reducing production costs.

[0062] In this embodiment, stainless steel, copper, aluminum and other metal materials can be obtained through physical screening, which is convenient to operate and does not require the use of chemical reagents for wet recycling, thus saving reagent costs. Moreover, the recycling process has better environmental protection and is suitable for widespread use.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recycling waste lithium-ion battery materials, characterized in that, Includes the following steps: Pretreatment steps: Discharge and crush the lithium-ion battery to obtain crushed products; Alcohololysis step: A reaction vessel is provided, and liquid alcohololysis agent and the crushed product are added to the reaction vessel. The temperature inside the reaction vessel is adjusted to 180-250℃, so that the alcohololysis agent inside the reaction vessel is in a supercritical or subcritical state. The alcohololysis agent and the crushed product undergo alcohololysis to obtain alcohololysis product. The alcohololysis agent is methanol. In the alcohololysis step, the liquid-solid ratio of the alcohololysis agent to the crushed product is 1ml:1g to 10ml:1g, the alcohololysis time is 10-30min, the stripping rate of positive and negative electrode materials reaches more than 99%, and the diaphragm and plastic shell in the crushed product are removed by alcohololysis with the methanol. Post-processing steps; The alcoholysis products were separated to obtain black powder, stainless steel, copper, and aluminum. The post-processing steps include: Shaking separation step: A shaking separator is provided, the shaking separator including a screen with a mesh size of 60 to 200; the alcoholysis product is placed into the screen and the alcoholysis product on the screen is shaken to obtain a mixed coarse material located above the screen; Drying step: A drying device is provided, the mixed coarse material is added to the drying device and the mixed coarse material is dried; Multi-stage screening step: A vibrating screen is provided to convey the dried mixture to the vibrating screen for multi-stage screening. The mesh size of the vibrating screen is 60 mesh to 200 mesh. The screening results in oversize material and undersize material. The oversize material is a mixed metal material including stainless steel, copper and aluminum, and the undersize material is black powder.

2. The method for recycling waste lithium-ion battery materials according to claim 1, characterized in that, The recovery method further includes an alcoholysis agent recovery step: In the shaking separation step, the alcoholysis product on the screen is shaken to obtain a waste liquid containing a certain amount of black powder located below the screen; a preheater and a recovery tower are provided, the inlet of the preheater is connected to the drying device, and the outlet of the preheater is connected to the recovery tower. The preheater is used to heat the waste liquid, and gaseous alcoholysis agent escapes from the waste liquid during heating. The recovery tower is used to cool the gaseous alcoholysis agent that escapes from the waste liquid during heating. The temperature inside the recovery tower is 90-110℃. In the drying step, the drying temperature is 90-110℃ and the drying time is 10-15min. During the drying process, the mixed coarse material releases gaseous alcoholysis agent, which is then condensed and recovered.

3. The method for recycling waste lithium-ion battery materials according to claim 2, characterized in that, The oscillation separation step also includes adjusting and changing the mesh size of the sieve according to the particle size of the black powder.

4. The method for recycling waste lithium-ion battery materials according to any one of claims 1 to 3, characterized in that, The preprocessing steps include: Discharge steps: After disassembling the lithium-ion battery, the lithium battery cell is obtained. The lithium battery cell is immersed in an aqueous solution for 24-48 hours to discharge. Then, the discharged lithium battery cell is drained. The aqueous solution is an aqueous solution of sodium chloride, potassium chloride or sodium sulfate with a mass fraction of 5-10 wt%. Crushing step: The drained lithium battery cells are crushed to obtain crushed products.

5. The method for recycling waste lithium-ion battery materials according to claim 4, characterized in that, In the crushing step, the lithium battery cell is placed into the crushing chamber of the crusher for crushing, and inert gas is introduced into the crushing chamber to maintain a nitrogen atmosphere and a negative pressure environment.

6. The method for recycling waste lithium-ion battery materials according to claim 4, characterized in that, In the crushing step, the width of the crushed product is ≤20mm and the length of the crushed product is ≤20mm.

7. The method for recycling waste lithium-ion battery materials according to any one of claims 1 to 3, characterized in that, It also includes a metal magnetic separation step: A magnetic separator is provided to separate the mixed metal materials, thereby separating the magnetic stainless steel from the non-magnetic aluminum and copper, and obtaining stainless steel products and a mixture of copper and aluminum.

8. The method for recycling waste lithium-ion battery materials according to any one of claims 1 to 3, characterized in that, It also includes the eddy current separation step: We provide eddy current separators to separate copper and aluminum mixtures.

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