A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries

Abstract

The present invention relates to a green and efficient method for recovering metals in positive electrode materials of ternary lithium batteries. The method comprises the following steps: (1) separation: separating the waste ternary positive electrode materials to be treated by a phosphatidylcholine-based interfacial active separation method to obtain aluminum foil and a first positive electrode active material; (2) calcination; (3) leaching: leaching the second positive electrode active material by a deep eutectic solvent to obtain leached residue and leaching liquid; (4) recovery. The present invention provides a novel green recovery technology, namely "phosphatidylcholine-assisted deep eutectic solvent-citric acid synergistic system", which is used to efficiently recover precious metals in positive electrode materials of ternary lithium batteries; the method utilizes the interfacial activity of phosphatidylcholine, the strong solubility of deep eutectic solvent, and the dual functions of citric acid in the process of stripping and precipitation to achieve high-efficiency separation and recovery of metals such as lithium, nickel, and cobalt in waste batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling, and in particular to a green and efficient method for recycling metals in positive electrode materials of ternary lithium batteries. Background Art

[0002] At present, with the rapid development of the new energy vehicle industry worldwide, lithium batteries have entered a peak period of waste. Efficient recovery of nickel, cobalt and lithium elements in waste batteries can alleviate the long-standing problem of shortage of raw materials for battery production in my country. The content of precious metals in the positive electrode of lithium batteries is much higher than that of natural metal deposits, and has extremely high recycling value. For the recycling of ternary battery materials, the current methods mainly include pyrometallurgy, hydrometallurgy and biological recovery.

[0003] Pyrometallurgy usually requires a relatively high temperature (>1000°C) to melt battery waste into alloys or soluble metal compounds, while organic matter such as electrolytes and plastics are oxidized and decomposed to be removed. However, it has high energy consumption and high processing costs. In contrast, traditional hydrometallurgical processes usually use acidic or alkaline solutions to achieve efficient dissolution of the positive electrode active materials of discarded ternary lithium batteries by adding additional reducing agents or oxidizing agents, and combine co-precipitation and sol-gel methods to recover valuable metals in the leachate. The key to this process lies in the selection of the leaching system. By controlling the leaching conditions (temperature, time, solid-liquid ratio, etc.), the positive electrode active materials are efficiently dissolved, and there are also problems of large investment, long process and secondary pollution. Therefore, it is urgent to develop new environmentally friendly solvents and design corresponding processes to meet actual production needs.

[0004] Biorecycling technology uses microorganisms or bioenzymes to transform or decompose useful substances in the positive electrode materials of waste lithium batteries. This technology uses the metabolic capacity and enzyme catalysis of organisms to efficiently convert organic matter and metal ions in the positive electrode materials of waste lithium batteries into useful compounds. However, the cultivation and maintenance of microorganisms require high costs and precisely controlled environmental conditions, and the growth rate of microorganisms and the activity of enzymes are affected by many factors, such as temperature, pH value, nutrients, etc. Therefore, in order to realize the commercial application of biorecycling technology, further research and improvement are needed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a green and efficient method for recovering metals in the positive electrode materials of ternary lithium batteries. The purpose is to greatly shorten the leaching time, realize the green extraction of precious metals in the positive electrode materials of waste ternary lithium batteries, reduce the recycling cost of waste ternary lithium batteries, and thus improve the battery recycling efficiency.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A green and efficient method for recovering metals in positive electrode materials of ternary lithium batteries comprises the following steps:

[0008] (1) separation: separating the waste ternary cathode material to be treated by a phosphatidylcholine-based interfacial active separation method to obtain an aluminum foil and a first cathode active material;

[0009] (2) calcining: calcining the first positive electrode active material to remove non-metallic materials to obtain a second positive electrode active material;

[0010] (3) Leaching: Leaching the second positive electrode active material using a deep eutectic solvent to obtain a leached residue and a leachate;

[0011] (4) Recovery: recovering the leached residue; adding an organic solvent containing citric acid to the leachate for stripping to obtain nickel, cobalt and manganese precipitates and a first lithium-containing solution; distilling the first lithium-containing solution to obtain citric acid, deep eutectic solvent components and a second lithium-containing solution; and calcining the second lithium-containing solution to obtain a lithium salt.

[0012] Based on the above technical solution, the present invention can also be improved as follows.

[0013] Among them, the waste ternary lithium batteries are discharged, disassembled, crushed and sorted in sequence to obtain the waste ternary positive electrode materials to be processed; the specific process is to discharge the waste ternary lithium batteries by soaking them in 5% NaCl solution, and then use foam boards to sort the waste ternary positive electrode materials to be processed.

[0014] Furthermore, the parameters of the phosphatidylcholine-based interfacial active separation method in step (1) are as follows: the mass concentration of phosphatidylcholine is 30 g / L-50 g / L (the concentration of phosphatidylcholine in the sum of phosphatidylcholine and waste ternary positive electrode material), the solid-liquid ratio is 8-12:1, the reaction temperature is 40°C-60°C, and the reaction time is 4h-6h.

[0015] Furthermore, in step (2), the calcination temperature is 400° C.-600° C., and the calcination time is 3 h-8 h; for example, in a muffle furnace;

[0016] The non-metallic material in step (2) includes PVDF and conductive carbon black.

[0017] Furthermore, step (3) includes the following specific steps: adding the deep eutectic solvent and the second positive electrode active material into a hydrothermal autoclave liner, placing the hydrothermal autoclave liner in a steel shell of a high-pressure reactor; placing the high-pressure reactor in a homogeneous reactor with heating and flipping functions, heating to a target temperature of 105°C-115°C, setting the speed to a maximum value of 60rpm, heating and flipping for 4h-8h, taking out the high-pressure reactor and cooling it to room temperature, and separating to obtain leaching residue and leachate.

[0018] In the step (7), the leached residue is recovered, washed repeatedly with deionized water and anhydrous ethanol for three times, and then dried in an oven at 90° C. for 12 hours.

[0019] Furthermore, the deep eutectic solvent in step (3) is mainly prepared by hydrogen bond acceptors and hydrogen bond donors in a molar ratio of 1:8-16. The preparation conditions of the deep eutectic solvent are as follows: place the glass bottle in a heat-collecting magnetic stirrer and stir it in a water bath at 60°C for 30 minutes to obtain clear and transparent DESs. The solvent obtained above is sealed and placed in a desiccator and stored at room temperature.

[0020] Furthermore, the hydrogen bond acceptor includes at least one of dihydrated 5-sulfosalicylic acid, malic acid, and maleic acid, and the hydrogen bond donor includes at least one of ethylene glycol, malonic acid, and urea.

[0021] Furthermore, the usage ratio of the deep eutectic solvent to the second positive electrode active material is 40 g / L-60 g / L.

[0022] Furthermore, in step (4), the volume ratio of the leachate to the organic solvent containing citric acid is 1.0-1.6:1.

[0023] Furthermore, the organic solvent containing citric acid in step (4) includes citric acid, dimethylglyoxime and oxalic acid; the volume ratio of the citric acid, the dimethylglyoxime and the oxalic acid is 1:1:1.

[0024] Furthermore, in step (4), the distillation treatment of the first lithium-containing solution includes atmospheric distillation and reduced pressure distillation in sequence; citric acid and oxalic acid are obtained by atmospheric distillation; and components of the deep eutectic solvent are obtained by reduced pressure distillation.

[0025] The present invention adopts phosphatidylcholine as an amphiphilic surfactant, which works synergistically with a deep eutectic solvent (DESs) of a specific ratio, and utilizes the dual functions of citric acid - as a stripping agent to promote the transfer of metal ions, and as a precipitating agent to participate in the precipitation of metal citrates; through this integrated innovative method, the present invention achieves efficient dissolution and selective extraction of precious metals such as lithium, nickel, and cobalt in the positive electrode materials of waste ternary lithium batteries.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention provides a novel green recycling technology, namely "phosphatidylcholine-assisted deep eutectic solvent-citric acid synergistic system", which is used to efficiently recover precious metals in the positive electrode materials of ternary lithium batteries; this method utilizes the interfacial activity of phosphatidylcholine, the strong solubility of deep eutectic solvents, and the dual functions of citric acid in the stripping and precipitation processes to achieve high-efficiency separation and recovery of metals such as lithium, nickel, and cobalt in waste batteries.

[0028] (2) The present invention reduces interfacial tension through phosphatidylcholine to promote metal ion transfer, combines the environmental friendliness and efficient dissolution characteristics of deep eutectic solvents with the synergistic effect of citric acid in precipitation and stripping, and the present invention not only improves the metal recovery rate, but also reduces energy consumption and environmental impact, thus opening up a new path for the environmentally friendly recycling of waste batteries.

[0029] (3) The present invention prepares a deep eutectic solvent with a hydrogen bond acceptor and a hydrogen bond donor in a certain molar ratio, wherein the hydrogen bond acceptor is selected from 5-sulfosalicylic acid dihydrate (SAD), and the hydrogen bond donor is selected from ethylene glycol (EG). Based on the strong coordination characteristics of the low-viscosity component ethylene glycol and the high-efficiency coordination and dissolving component 5-sulfosalicylic acid dihydrate, a low-viscosity acid-based DESS (EG:SAD) high-efficiency leaching system is prepared; compared with other solvents, the deep eutectic solvent is generally cheap, easy to obtain, easy to prepare, relatively non-toxic and biodegradable. By adopting this process, DESs and EG can be reused multiple times by reduced pressure distillation, which can effectively reduce the recycling cost of waste ternary lithium battery positive electrode materials and improve battery recycling efficiency.

[0030] (4) The present invention uses phosphatidylcholine as an amphiphilic surfactant, which significantly enhances the interfacial activity of the solution with its unique polar head and non-polar tail structure; by precisely controlling its concentration in the leaching system, phosphatidylcholine not only reduces the interfacial tension during metal ion transfer, but also promotes the affinity between the positive electrode active material and the solvent; the phosphatidylcholine-assisted strategy of the present invention, based on its biocompatibility and environmental friendliness, provides a green and efficient way for the efficient separation of the positive electrode materials of ternary lithium batteries, further enhancing the performance and sustainability of the entire recycling process.

[0031] (5) In the present invention, citric acid plays a dual role, being both a stripping agent and a precipitating agent. This innovative application significantly improves the recovery efficiency of metal ions. As a stripping agent, citric acid effectively promotes the transfer of metal ions from the organic phase to the aqueous phase by forming a stable water-soluble complex with metal ions. During the precipitation process, citric acid reacts with metal ions to form insoluble metal citrates, simplifying the subsequent separation and purification steps. This dual-function application of citric acid not only improves the selectivity and efficiency of the recovery process, but also reduces the generation of chemical waste, reflecting the dual advantages of environmental protection and economy in the field of battery recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow diagram of the present invention. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0034] Sources of materials and reagents:

[0035] This embodiment relates to a green and efficient method for recovering metals in anode materials of a ternary lithium battery, comprising the following steps:

[0036] (1) separation: separating the waste ternary cathode material to be treated by a phosphatidylcholine-based interfacial active separation method to obtain an aluminum foil and a first cathode active material;

[0037] (2) calcining: calcining the first positive electrode active material to remove non-metallic materials to obtain a second positive electrode active material;

[0038] (3) Leaching: Leaching the second positive electrode active material using a deep eutectic solvent to obtain a leached residue and a leachate;

[0039] (4) Recovery: recovering the leached residue; adding an organic solvent containing citric acid to the leachate for stripping to obtain nickel, cobalt and manganese precipitates and a first lithium-containing solution; distilling the first lithium-containing solution to obtain citric acid, deep eutectic solvent components and a second lithium-containing solution; and calcining the second lithium-containing solution to obtain a lithium salt.

[0040] Among them, the waste ternary lithium batteries are discharged, disassembled, crushed and sorted in sequence to obtain the waste ternary positive electrode materials to be processed; the specific process is to discharge the waste ternary lithium batteries by soaking them in 5% NaCl solution, and then use foam boards to sort the waste ternary positive electrode materials to be processed.

[0041] In this embodiment, the parameters of the phosphatidylcholine-based interfacial active separation method in step (1) are as follows: the mass concentration of phosphatidylcholine is 30 g / L-50 g / L (the concentration of phosphatidylcholine in the sum of phosphatidylcholine and waste ternary positive electrode material), for example, 30 g / L, 40 g / L, 50 g / L, etc., the solid-liquid ratio is 8-12:1, for example, 8:1, 10:1, 12:1, etc., the reaction temperature is 40°C-60°C, for example, 40°C, 50°C, 60°C, etc., and the reaction time is 4h-6h, for example, 4h, 5h, 6h, etc.

[0042] In this embodiment, the calcination temperature in step (2) is preferably 400° C.-600° C., such as 400° C., 500° C., 600° C., etc., and the calcination time is 3 h-8 h, such as 3 h, 5 h, 8 h, etc.; for example, it is carried out in a muffle furnace;

[0043] The non-metallic material in step (2) includes PVDF and conductive carbon black.

[0044] In this embodiment, step (3) includes the following specific steps: adding the deep eutectic solvent and the second positive electrode active material into a hydrothermal autoclave liner, and placing the hydrothermal autoclave liner in a steel shell of a high-pressure reactor; placing the high-pressure reactor in a homogeneous reactor with heating and flipping functions, heating to a target temperature of 105°C-115°C, such as 105°C, 110°C, 115°C, etc., setting the rotation speed to a maximum value of 60rpm, heating and flipping for 4h-8h, such as 4h, 6h, 8h, etc., taking out the high-pressure reactor and cooling it to room temperature, and separating to obtain leaching residue and leachate.

[0045] The leached residue was recovered by repeatedly washing with deionized water and anhydrous ethanol for three times and then drying in an oven at 90°C for 12 hours.

[0046] In this embodiment, the deep eutectic solvent in step (3) is mainly prepared by hydrogen bond acceptors and hydrogen bond donors in a molar ratio of 1:8-16, such as 1:8, 1:12, 1:16, etc. The configuration conditions of the deep eutectic solvent are as follows: the glass bottle is placed in a heat-collecting magnetic stirrer and stirred for 30 minutes in a water bath at 60°C to obtain clear and transparent DESs. The solvent obtained above is sealed and placed in a desiccator and stored at room temperature. The hydrogen bond acceptor includes at least one of dihydrated 5-sulfosalicylic acid, malic acid, and maleic acid, and the hydrogen bond donor includes at least one of ethylene glycol, malonic acid, and urea. The dosage ratio of the deep eutectic solvent to the second positive electrode active material is 40g / L-60g / L, such as 40g / L, 50g / L, 60g / L, etc.

[0047] In this embodiment, the volume ratio of the leachate to the organic solvent containing citric acid in step (4) is preferably 1.0-1.6:1, such as 1.0:1, 1.3:1, 1.6:1, etc. The organic solvent containing citric acid in step (4) includes citric acid, dimethylglyoxime and oxalic acid; the volume ratio of the citric acid, dimethylglyoxime and oxalic acid is 1:1:1. The distillation treatment of the first lithium-containing solution in step (4) includes atmospheric distillation and reduced pressure distillation in sequence; citric acid and oxalic acid are obtained by atmospheric distillation; and components of the deep eutectic solvent are obtained by reduced pressure distillation.

[0048] In summary, the present invention uses phosphatidylcholine as an amphiphilic surfactant, synergistically with a deep eutectic solvent (DESs) of a specific ratio, and utilizes the dual functions of citric acid - as a stripping agent to promote the transfer of metal ions, and as a precipitant to participate in the precipitation of metal citrates; through this integrated innovative method, the present invention achieves efficient dissolution and selective extraction of precious metals such as lithium, nickel, and cobalt in the cathode materials of waste ternary lithium batteries. The following is further explained with specific examples and comparative examples.

[0049] Example 1

[0050] The present embodiment provides a green and efficient method for recovering precious metals in the positive electrode material of a ternary lithium battery using a phosphatidylcholine-deep eutectic solvent system with integrated citric acid bifunctional assistance, comprising the following specific steps: Figure 1 ):

[0051] Step 1, sorting:

[0052] The positive and negative black powder of the dismantled and crushed waste ternary 111 lithium batteries are sorted and divided into waste ternary 111 positive electrode materials and waste negative electrode materials according to their physical and chemical properties. The specific method is foam sorting: after sorting, the waste ternary 111 positive electrode materials remain at the bottom, and the waste negative electrode materials float up.

[0053] Step 2: Separation:

[0054] The positive electrode active material is separated by the phosphatidylcholine-based interfacial active separation method to obtain aluminum foil and other positive electrode active materials; the concentration of phosphatidylcholine is controlled to be 40g / L, the solid-liquid ratio is 10:1, the temperature is 60°C, and the reaction time is 5 hours.

[0055] Step 3, calcination:

[0056] The impurities such as PVDF and conductive carbon black were removed by calcination in a muffle furnace to obtain a positive electrode active material with higher purity. The calcination temperature was 500°C and the calcination time was 5 hours.

[0057] Step 4: Determination:

[0058] Add 2g of discarded ternary cathode active material to a beaker containing 40mL of aqua regia solution (10ml of concentrated nitric acid + 30ml of concentrated hydrochloric acid). After sealing the beaker with plastic wrap, stir in a 90°C water bath for 3h to fully dissolve the active material and obtain a clear solution. Finally, an inductively coupled plasma atomic emission spectrometer (ICP-AES) was used to determine the metal (lithium, nickel, cobalt and manganese) content in the clear solution. Based on the mass ratio of lithium, nickel, cobalt, manganese and oxygen, the molar ratio of each element in the active material was calculated to determine its chemical formula.

[0059] Step 5, liquid preparation:

[0060] A deep eutectic solvent is prepared, wherein the deep eutectic solvent is prepared by a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:12; the hydrogen bond acceptor is 5-sulfosalicylic acid dihydrate (SAD), and the hydrogen bond donor is ethylene glycol (EG). The glass bottle is placed in a heat-collecting magnetic stirrer and stirred in a water bath at 60°C for 30 minutes to obtain DESs.

[0061] Step 6, leaching:

[0062] A certain amount of waste ternary 111 cathode material is placed in a deep eutectic solvent for leaching. The temperature is raised to the target temperature of 110°C, the speed is set to 60rpm, heated and flipped for 6 hours, and then taken out after cooling to room temperature. The slurry is filtered to obtain the leachate and leach residue.

[0063] Step 7, Recycling:

[0064] The leached residue is recovered by washing it repeatedly with deionized water and anhydrous ethanol for 3 times, and then drying it in an oven at 90°C for 12 hours. The leached solution is recovered by mixing it with citric acid, dimethylglyoxime and oxalic acid solution, and stirring it at room temperature to obtain a lithium-containing solution and nickel-cobalt-manganese precipitate. Citric acid, dimethylglyoxime and oxalic acid solution are mixed in a 100mL beaker in a volume ratio of 1:1 and stirred for 30 minutes to obtain a lithium-containing solution and nickel-cobalt-manganese precipitate.

[0065] Step 8, distillation:

[0066] The lithium-containing solution is subjected to atmospheric distillation to separate citric acid, oxalic acid solution and DESs solution. The DESs are distilled under reduced pressure to obtain regenerated EG and lithium solution, and the lithium solution is calcined at high temperature to obtain lithium salt (Li 2 SO 4 ). The atmospheric distillation temperature is 150°C, and the magnetic stirring is 3h; the reduced pressure distillation temperature is 220°C, and the magnetic stirring is 1h; the high temperature calcination temperature is 700°C, and the time is 3h.

[0067] Finally, through calculation, the leaching efficiency of Li is 93.1%, the leaching efficiency of Co is 96.3%, the leaching efficiency of Ni is 94.2%, and the leaching efficiency of Mn is 97.4%.

[0068] Comparative Example 1

[0069] Compared with Example 1, except for the following differences, the rest are the same as Example 1: NaOH is used as the separation agent, the separation time is set to 30 minutes, DESs is used as the extraction agent, the leaching time is set to 6 hours, sulfuric acid is used as the stripping agent, and oxalic acid is used as the precipitating agent.

[0070] Comparative Example 2

[0071] Compared with Example 1, except for the following differences, the rest is the same as Example 1: except that NaOH is used as the separation agent, the separation time is set to 30 minutes, DESs is used as the extraction agent, the leaching time is set to 6 hours, and citric acid is used as the stripping agent and precipitant.

[0072] Comparative Example 3

[0073] Compared with Example 1, except for the following differences, the rest is the same as Example 1: phosphatidylcholine is used as a separation agent, DESs is used as an extractant, the leaching time is set to 6 hours, sulfuric acid is used as a stripping agent, and oxalic acid is used as a precipitant.

[0074] Test example

[0075] (1) Separation efficiency

[0076] Separation efficiency refers to the ratio of the amount of positive electrode material and aluminum foil separated by the separator to the total amount of positive electrode material.

[0077] (2) Leaching efficiency

[0078] Leaching efficiency refers to the ratio of the amount of cathode material dissolved by the extractant to the total amount of cathode material.

[0079] (3) Lithium recovery efficiency

[0080] The lithium recovery efficiency refers to the ratio of the mass of lithium obtained by the precipitant and the stripping agent to the total mass of lithium.

[0081] (4) Efficiency of recovering transition metal elements

[0082] The efficiency of recovering transition metal elements refers to the ratio of the mass of transition elements obtained by precipitating agent and stripping agent to the total mass of transition elements.

[0083] (5) Cost

[0084] The cost refers to the price of using the reagent ten times per group, which can be obtained by converting the total price and usage of each reagent.

[0085] Table 1 is a comparison of the reagents used in the examples and the comparative examples and the results

[0086]

[0087]

[0088] In summary, the present invention proposes a novel green recycling technology, namely "phosphatidylcholine-assisted deep eutectic solvent-citric acid synergistic system", which is used to efficiently recover precious metals in the positive electrode materials of ternary lithium batteries; this method utilizes the interfacial activity of phosphatidylcholine, the strong solubility of deep eutectic solvents, and the dual functions of citric acid in the stripping and precipitation processes to achieve high-efficiency separation and recovery of metals such as lithium, nickel, and cobalt in waste batteries.

[0089] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries, characterized in that: The steps include: (1) Separation: Separating the waste ternary cathode material to be treated by a phosphatidylcholine-based interfacial active separation method to obtain aluminum foil and a first cathode active material; (2) Calcination: calcining the first positive electrode active material to remove non-metallic materials and obtain a second positive electrode active material; (3) Leaching: Leaching the second cathode active material with a deep eutectic solvent to obtain a leached residue and a leachate; (4) Recovery: recovering the leached residue; adding an organic solvent containing citric acid to the leaching solution for stripping to obtain nickel, cobalt and manganese precipitates and a first lithium-containing solution; distilling the first lithium-containing solution to obtain citric acid, deep eutectic solvent components and a second lithium-containing solution; and calcining the second lithium-containing solution to obtain a lithium salt; The parameters of the phosphatidylcholine-based interfacial active separation method in step (1) are as follows: the mass concentration of phosphatidylcholine is 30 g / L-50 g / L, the solid-liquid ratio is 8-12:1, the reaction temperature is 40°C-60°C, and the reaction time is 4h-6h; The deep eutectic solvent in step (3) is prepared from a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:8-16; the hydrogen bond acceptor includes at least one of dihydrate 5-sulfosalicylic acid, malic acid, and maleic acid, and the hydrogen bond donor includes at least one of ethylene glycol, malonic acid, and urea; The organic solvent containing citric acid in step (4) comprises citric acid, dimethylglyoxime and oxalic acid; the volume ratio of the citric acid, the dimethylglyoxime and the oxalic acid is 1:1:

1.

2. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries according to claim 1, characterized in that: In step (2), the calcination temperature is 400°C-600°C, and the calcination time is 3h-8h; The non-metallic material in step (2) includes PVDF and conductive carbon black.

3. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries according to claim 1, characterized in that: Step (3) comprises the following specific steps: adding the deep eutectic solvent and the second positive electrode active material into a hydrothermal autoclave liner, placing the hydrothermal autoclave liner in a steel shell of a high-pressure reactor; placing the high-pressure reactor in a homogeneous reactor with heating and flipping functions, heating to a target temperature of 105°C-115°C, setting the rotation speed to a maximum value of 60 rpm, heating and flipping for 4h-8h, taking out the high-pressure reactor and cooling it to room temperature, and separating to obtain leaching residue and leachate.

4. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries according to claim 1, characterized in that: The solid-to-liquid ratio of the deep eutectic solvent to the second positive electrode active material is 40 g / L-60 g / L.

5. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries according to claim 1, characterized in that: In step (4), the volume ratio of the leaching solution to the organic solvent containing citric acid is 1.0-1.6:

1.

6. A green and efficient method for recovering metals from positive electrode materials of ternary lithium batteries according to claim 1, characterized in that: In step (4), the first lithium-containing solution is subjected to distillation treatment, which includes atmospheric distillation and reduced pressure distillation in sequence; citric acid and oxalic acid are obtained by atmospheric distillation; and components of the deep eutectic solvent are obtained by reduced pressure distillation.

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